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 Select Review on smart highways critical technology Jianqing WU,Xiuguang SONG Journal of Shandong University(Engineering Science)    2020, 50 (4): 52-69.   DOI: 10.6040/j.issn.1672-3961.0.2020.149 Abstract （1170）   HTML （484）    PDF（pc） （2579KB）（1076）       Save Giving highway engineering "wisdom" and establishing new generation five-in-one system of "Internet+" design, construction, management, monitoring and operation, namely, the smart highway, was the hot issue of the interdisciplinary study of civil engineering, control engineering, mechanical engineering, transportation engineering, and computer science. To comprehensively understand the smart highway, this review focused on the critical technology in the integrated system in full life-cycle of the smart highway as well as systematically investigated the relevant previous efforts, critical common technologies, and future scopes on multi-function pavement material, smart construction, smart detection, autonomous vehicles, connected vehicles, and internet of things technology.
 Select Review of capsule network Jucheng YANG,Shujie HAN,Lei MAO,Xiangzi DAI,Yarui CHEN Journal of Shandong University(Engineering Science)    2019, 49 (6): 1-10.   DOI: 10.6040/j.issn.1672-3961.0.2019.312 Abstract （1700）   HTML （105）    PDF（pc） （4331KB）（998）       Save Recently capsule network with dynamic routing was the new neural network model which was considered a significant model in next generation. In recent years, much research evidenced capsule network exceptional ability to fit features. But the high computational overhead made it unable to fit complex and large datasets. Consequently, reducing computational became a research hotspot. There were two methods, including optimized capsule and optimized routing, to solve the issue. Optimized capsule was usually driven by application purpose which was designed as a model of specific classification tasks. And optimized routing was the way to improve the performance of the model from an algorithmic perspective.
 Select Unmanned vehicle path planning based on deep Q learning in real environment Hao XIAO,Zhuhua LIAO,Yizhi LIU,Silin LIU,Jianxun LIU Journal of Shandong University(Engineering Science)    2021, 51 (1): 100-107.   DOI: 10.6040/j.issn.1672-3961.0.2020.247 Abstract （481）   HTML （22）    PDF（pc） （6074KB）（904）       Save It was an important problem for the intelligent navigation of unmanned vehicles that planning the optimal path in the actual traffic environment. At present, many researches about global path planning of unmanned vehicle mainly focused on the improvement of algorithm solution speed in the simulation environment. Most of them just only considered the optimal path distance or the current road conditions, also ignored other factors and future changes in the actual environment. In order to complete the complex task that competing global path planning of unmanned vehicle in dynamic road network, this research put forward a framework of unmanned vehicle driving system for practical environment based on the thought of planning after prediction, and put forward DP-DQN which was a fast global path planning method combined with deep Q learning and deep prediction network technology. This method used the road characteristic data such as time and space, weather et al to predict the future traffic situation, and then competed the global optimal path. Finally, experimental results based on open datasets showed that the proposed method reduced driving time 17.97% at most than Dijkstra, A*, algorithm et al.
 Select Review on application of artificial intelligence in power system restoration Yutian LIU, Runjia SUN, Hongtao WANG, Xueping GU Journal of Shandong University(Engineering Science)    2019, 49 (5): 1-8.   DOI: 10.6040/j.issn.1672-3961.0.2019.122 Abstract （944）   HTML （55）    PDF（pc） （1128KB）（890）       Save The research results of expert system, fuzzy mathematics, evolutionary algorithm and machine learning in power system restoration were summarized. It was pointed out that the existing researches were mainly offline restoration method and the researches about online decision-making were in the initial stage. In addition, the application potential of artificial intelligence technology in system restoration was prospected.
 Select Review of energy consumption and demand forecasting methods Ming YANG,Pingjing DU,Fengquan LIU,Xupeng HAO,Yifan BO Journal of Shandong University(Engineering Science)    2020, 50 (1): 56-62,71.   DOI: 10.6040/j.issn.1672-3961.0.2019.180 Abstract （1064）   HTML （942）    PDF（pc） （2290KB）（836）       Save In view of the increasing dependence of energy planning on energy demand forecasting and the difficulty of energy demand forecasting, this paper analyzed various energy forecasting methods and discussed the direction of energy development. The article analyzed the current demand situation of energy development methods from the direction of global energy demand development in recent years. The existing main energy forecasting methods were summarized and compared. The advantages and disadvantages of the existing research methods and applicable occasions were summarized. Combined with the new direction of energy development, the future development prospects of energy forecasting were given. Furthermore, this paper applied the LEAP model to predict the energy demand of the African region, and analyzed the regional energy complementation effect and the role of "electricity substitution" in the development of energy demand.
 Select Phase change characteristics of paraffin in rectangular storage unit Huilin ZHOU,Yan QIU Journal of Shandong University(Engineering Science)    2019, 49 (4): 99-107.   DOI: 10.6040/j.issn.1672-3961.0.2019.018 Abstract （815）   HTML （8）    PDF（pc） （3235KB）（834）       Save To study the heat transfer characteristics of phase change material (PCM) in a storage unit and improve the heat transfer efficiency of phase change heat exchanger, the enthalpy-porous media model and FLUENT program were used to carry out a numerical investigation on the heat transfer process of paraffin in a rectangular heat storage unit. The element liquid fraction β and dimensionless Fo, Ste and Ra were introduced to analyze the influences of different positions outside the tube and inlet temperatures of heat transfer fluid on the melting and solidification process of paraffin. The results showed that the paraffin outside the tube was melted in order from the upper to the left/right part, then the lower part. The total melting time of paraffin in upper part was shorten by at least 20% compared with other parts. Conversely, in the heat release process, the paraffin was solidified in order from the lower, the left/right part and the upper part. The heat transfer mechanism in the unit changed gradually from heat conduction to natural convection in the thermal storage process. The efficiency of heat storage and release could be improved significantly by increasing the temperature difference between heat transfer fluid and paraffin. The criterion of β was obtained by polynomial fitting.
 Select A survey of image captioning methods based on deep learning Zhifu CHANG,Fengyu ZHOU,Yugang WANG,Dongdong SHEN,Yang ZHAO Journal of Shandong University(Engineering Science)    2019, 49 (6): 25-35.   DOI: 10.6040/j.issn.1672-3961.0.2019.244 Abstract （2298）   HTML （63）    PDF（pc） （7881KB）（826）       Save Image captioning is the cross-research direction of computer vision and natural language processing. This paper aimsed to summarize the deep learning methods in the field of image captioning. Imgage captioning methods based on deep learning was summarized into five categories: multimodal space based method, multi-region based method, enconder-deconder based method, reinforcement learning based method, and generative adversarial networks based method.The datasets and evaluation metrics were demonstrated, and experimental result of different methods were compared. The three key problems and future research direction for image captioning were presented and summarized.
 Select Object detection of 3D point clouds based on F-PointNet Peng WAN Journal of Shandong University(Engineering Science)    2019, 49 (5): 98-104.   DOI: 10.6040/j.issn.1672-3961.0.2018.348 Abstract （2241）   HTML （40）    PDF（pc） （3128KB）（808）       Save Aiming at the problem of poor detection accuracy of the current 3D point cloud object detection model, the F-PointNet model, which directly processed point cloud data, was used to detect cars, pedestrians and cyclists, and the model was fine-tuned to further improve the object detection accuracy. The model was tested by different parameter initialization methods, $\ell$2 regularization and modifying convolution kernels. The experimental results showed that the Xavier parameter initialization method converged faster 0.09s than the truncated normal distribution method, and the vehicle detection accuracy and the cyclists detection accuracy was about 3% and 2% higher respectively. By adding $\ell$2 regularization, the detection accuracy of pedestrians and cyclists was increased by about 2% and 1% respectively. By reducing the number of convolution kernels in the first layer of T-Net (Transformer Networks) to 128, the detection accuracy of cars and cyclists was increased by about 1% and 2% respectively, which confirmed that the model could effectively improve object detection accuracy.
 Select Cross-domain text sentiment classification based on domain-adversarialnetwork and BERT Guoyong CAI,Qiang LIN,Kaiqi REN Journal of Shandong University(Engineering Science)    2020, 50 (1): 1-7,20.   DOI: 10.6040/j.issn.1672-3961.0.2019.293 Abstract （1192）   HTML （47）    PDF（pc） （1549KB）（711）       Save In order to capture more sentence semantic information from the extracted shared sentiment features for cross-domain sentiment analysis, a deep network model based on domain adversarial mechanism and BERT (bidirectional encoder representations from transformers) was proposed. The model firstly used BERT to obtain the semantic representation vectors of sentences, and then extracted the local features of sentences with a convolutional neural network. A domain adversarial neural network was designed to make the representations of features extracted from different domains to be as indistinguishable as possible, that was, the features extracted from source domain and target domain had much more similarities; and a sentiment classifier was trained on the source domain dataset with sentiment labels, and it was expected that the trained sentiment classifier would have good classification performance in the source domain, and in the target domain. The experimental results on Amazon product reviews dataset showed that the proposed method achieved the expectation and was competent for achieving cross-domain text sentiment classification.
 Select Air quality prediction approach based on integrating forecasting dataset Minghe GAO,Ying ZHANG,Rongrong ZHANG,Zihao HUANG,Linyan HUANG,Fanyu LI,Xin ZHANG,Yanhao WANG Journal of Shandong University(Engineering Science)    2020, 50 (2): 91-99.   DOI: 10.6040/j.issn.1672-3961.0.2019.404 Abstract （1078）   HTML （19）    PDF（pc） （4733KB）（688）       Save Towarding the air quality prediction research problem, LightGBM was employed to propose and design a predictive feature-based air quality prediction approach, which could effectively predict the PM2.5 concentration, i.e., the key indicator reflecting air quality, in the upcoming 24-hour within Beijing. During constructing the prediction solution, the features of the training data set was analyzed to execute data cleansing, and the methods of random forest and linear interpolation were used to solve the problem of high data loss and noise interference. The predictive data features were integrated into the dataset, and meanwhile the corresponding statistical features were designed to imiprove the prediction accurancy. The sliding window mechanism was used to mine high-dimensional time features and increase the quantity of data features. The performance and result of the proposed approach were analyzed in details through comparing with the basedline models. The experimental results showed that compared with other model methods, the proposed LightGBM-based prediction approach with integrating forecasting data had higher prediction accuracy.
 Select An automatic reading method for pointer meter Yanghao ZHOU,Yifan LIU,Li LI Journal of Shandong University(Engineering Science)    2019, 49 (4): 1-7.   DOI: 10.6040/j.issn.1672-3961.0.2018.275 Abstract （1280）   HTML （150）    PDF（pc） （4120KB）（680）       Save An automatic reading method for automatically monitoring pointer meter in substation was proposed based on the machine learning and image processing algorithms, which was consisted of two stages: meter detection and pointer recognition. The position of the meter in the input image was detected by using the fully convolutional networks, and then the patch of the meter was extracted. The interference of illumination and shadow on the pointer recognition was reduced by using histogram equalization, median filtering and bilateral filtering, and the tilt of shooting was rectified by using the affine transformation. The position of the pointer was detected via the improved Hough transform. The reading was obtained by computing the angle of the pointer. The results showed that the method could detect the pointer meter and recognize the reading accurately for the pointer instrument in the substation. The method showed good robustness to the disturbances such as illumination and shadow, which could significantly reduce the substation inspection personnel workload and improve the work efficiency.
 Select Experimental research on mechanical features model of prestressed mutual-anchored retaining wall Jianhong JIANG,Zhenyu YANG,Qi CHEN,Qingyu MENG,Hongbo ZHANG Journal of Shandong University(Engineering Science)    2019, 49 (4): 61-69.   DOI: 10.6040/j.issn.1672-3961.0.2018.165 Abstract （690）   HTML （3）    PDF（pc） （3546KB）（678）       Save To study the mechanical behaviors of the prestressed mutual anchoring retaining walls under different structural parameters, an indoor model test device was designed considering the mechanical mechanism and different prestress levels and different anchor placement positions. The results showed that due to the lateral restraint effect of the anchor (cable) on the wall and under the lateral prestress, the wall moved towards the direction of the filler, and gradually increased with the prestressing of the anchor. It evolved from T-model into the T+RB model. The earth pressure behind the wall gradually increased and it had a parabolic distribution with the peak at the anchor. According to the test results, the optimal anchoring position was recommended, and the range of anchored prestressing and optimal prestressing. The research results could be used to guide the design calculation of the prestressed mutual anchoring retaining walls.
 Select Abnormal sound detection of washing machines based on deep learning Chunyang LI,Nan LI,Tao FENG,Zhuhe WANG,Jingkai MA Journal of Shandong University(Engineering Science)    2020, 50 (2): 108-117.   DOI: 10.6040/j.issn.1672-3961.0.2019.419 Abstract （835）   HTML （19）    PDF（pc） （5582KB）（672）       Save Based on the convolutional neural network (CNN) framework, a model for abnormal sounds recognition of washing machine was proposed. According to the remarkable feature extraction ability and translation invariance of convolutional neural network, the abnormal sound features of washing machines were learned, so as to achieve the purpose of the automatic intelligent recognition of abnormal sounds for washing machines in production line. This method provided a complete process to solve the problems of training datasets establishment and data imbalance. A network model for data augmentation called advanced deep convolution generated adversarial network (ADCGAN)was proposed to solve the problem of training data scarcity. The traditional deep convolution generated adversarial network (DCGAN) model was improved to better adapt to the generation of industrial sounds. This model could be used to extend the original data and generate the abnormal sound augmented datasets of washing machine. The augmented datasets was used to train the convolutional neural network, and the test accuracy reached 0.999. The generalization ability of abnormal sounds recognition model for washing machine network was tested by using the data set with background noise signal added. The correct recognition rate reached 0.902, which indicated that this network had good robustness in recognizing abnormal noises of washing machines.
 Select Laminar flow field characteristics in the stirred vessel equipped with an eccentric-shaft impeller Meiting LI,Wei LI,Xiaoguang LI,Fengling YANG Journal of Shandong University(Engineering Science)    2019, 49 (4): 93-98, 107.   DOI: 10.6040/j.issn.1672-3961.0.2018.530 Abstract （876）   HTML （7）    PDF（pc） （2868KB）（627）       Save For the purpose of improving mixing efficiency of the stirred tank with high viscosity fluid laminar flow condition, an eccentric-shaft agitation method was proposed. With a purity of 99% glycerol as medium, and the traditional 2-flat-blade impeller as the research object, the laminar flow fields were numerically studied. The inner diameter of the stirred vessel was 0.3m and the agitated fluid was glycerol. The modeling reliability and simulation methods of the concentric agitation were validated by experimental results. In comparison with the concentric agitation, flow fields generated by eccentric and eccentric-shaft agitation were asymmetrical, and theoverall volume weitghted average velocity of the groove fluid generated by eccentric-shaft agitation could be raised by 68%. And furthermore, when operated under the same speed, the power consumption of eccentric-shaft agitation increased 15.3% than that of concentric agitation. However, the eccentric shaft agitation increased the speed in the tank and expanded the range of disturbance. Accordingly, the superiority of eccentric-shaft agitation of improving the mixing efficiency in the tank was apparent.
 Select Review of developments in titanium-based coagulants Baoyu GAO,Xin HUANG,Guangping YAO,Qinyan YUE Journal of Shandong University(Engineering Science)    2020, 50 (1): 109-114.   DOI: 10.6040/j.issn.1672-3961.0.2019.359 Abstract （856）   HTML （46）    PDF（pc） （1129KB）（595）       Save The development process and its applications of titanium-based coagulant were reviewed, including the mono-titanium coagulants and poly-titanium coagulants, and the single titanium coagulants and composite titanium coagulants, and the recent research process and the future development of titanium coagulants, which could provide guidances and references for the research and development of titanium-based coagulants.
 Select Entity alignment method based on adaptive attribute selection Jialin SU,Yuanzhuo WANG,Xiaolong JIN,Xueqi CHENG Journal of Shandong University(Engineering Science)    2020, 50 (1): 14-20.   DOI: 10.6040/j.issn.1672-3961.0.2019.415 Abstract （1119）   HTML （21）    PDF（pc） （1167KB）（571）       Save Most existing entity alignment methods typically relied on external information and required expensive manual feature construction to complete alignment. Knowledge graph-based methods used only semantic information and failed to use structural information. Therefore, this paper proposed a new entity alignment method based on adaptive attribute selection, training an entity alignment model based on the joint embedding of the two knowledge graphs, which combined the semantic and structural information. Also, this paper proposed the use of strong attribute constraint based on adaptive attribute selection, which could adaptively generate the most effective attribute category and weight, to improve the performance of entity alignment. Experiments on two realistic datasets showed that, compared with traditional methods, the precision of the proposed method was improved by 11%.
 Select Design of robot cloud service platform based on microservice Lei YIN,Fengyu ZHOU,Ming LI,Yugang WANG,Yinbo GUO,Ke CHEN Journal of Shandong University(Engineering Science)    2019, 49 (6): 55-62, 80.   DOI: 10.6040/j.issn.1672-3961.0.2019.251 Abstract （1048）   HTML （11）    PDF（pc） （4187KB）（568）       Save To improve the intelligent level of service robots, a cloud service design method for service robots based on micro-service was proposed in this paper. The framework of cloud service based on micro-service was designed based on virtual model of service robot. Kinematics model, sensor model and environment model were proposed to map the robot parameters to cloud center. The interactive interface for cloud services was proposed. The adaptive matching of heterogeneous protocols was realized by using the protocol response of robots. Cloud service development methods were proposed in detail. The experiment result were done to demonstrate the cloud service results, real time and fine-grained quality of service of the proposed cloud service design for service robots.
 Select Imprecise conditional probability prediction of wind power ramp events Bo WANG,Buwei WANG,Ming YANG,Yuanchun ZHAO,Wenli ZHU Journal of Shandong University(Engineering Science)    2020, 50 (1): 82-94.   DOI: 10.6040/j.issn.1672-3961.0.2019.178 Abstract （727）   HTML （6）    PDF（pc） （2669KB）（559）       Save Wind power ramp events (WPRE) could easily destroy the active power balance of the power system, as well as did harm to the frequency stability and power quality, which threatened the safe and stable operation of power grid. A novel imprecise conditional probability prediction approach was proposed based on the credal network (CN), which could provide the interval range of the occurrence probability of each WPRE state. The approach excavated the dependence relationships between WPRE and meteorological variables using the greedy search algorithm, and constructed a CN structure to express the relationships in an abstract way. The proposed approach extended the imprecise Dirichlet model (IDM) on hyperparameter settings to quantify the uncertain conditional dependences among the variables, thus to realize the parameter estimation of the CN. Based on the constructed CN model, a CN probability inference algorithm was employed to estimate the imprecise probability distribution of the multi-state WPRE. The case study with wind-farm operating measurements in Ningxia Province demonstrated that the proposed approach had excellent performance even under the prediction scenarios with insufficient samples.
 Select Design of triple-cables limiting-location anti-swing device for shipboard crane Zhaopeng REN,Rui XI,Shenghai WANG,Zhijiang ZHANG,Haiquan CHEN Journal of Shandong University(Engineering Science)    2020, 50 (3): 125-132142.   DOI: 10.6040/j.issn.1672-3961.0.2019.004 Abstract （696）   HTML （5）    PDF（pc） （4845KB）（548）       Save To reduce the payload pendulation of shipboard cranes, a mechanical anti-swing device based on triple-cables limiting-location was proposed. Three cables were used to pull the hook, which limited the spatial position of the payload to prevent the payload pendulation. According to the established kinematic model of the shipboard crane, the effect of length on the anti-swing was analyzed. The dynamic model of the payload system was established, and the effect of tension value on the anti-swing was analyzed. The models were verified by physical experiment based on a self-built test platform. The experimental results proved that the proposed mechanical anti-swing device based on triple-cables limiting-location had good anti-swing effect in practical applications. The overall anti-swing effect could reach more than 61%.
 Select Improved bird swarm algorithms based on mixed decision making Wei YAN,Damin ZHANG,Huijuan ZHANG,Ziyun XI,Zhongyun CHEN Journal of Shandong University(Engineering Science)    2020, 50 (2): 34-43.   DOI: 10.6040/j.issn.1672-3961.0.2019.294 Abstract （807）   HTML （9）    PDF（pc） （1356KB）（541）       Save Aiming at the problems of low precision and easy to fall into local optimum in solving complex function problems of traditional bird swarm algorithm (BSA), an improved bird swarm algorithm based on mixed decision-making was proposed while retaining the simplicity of BSA. The centroid opposition-based learning was used to initialize the bird population and maintain the better spatial solution distribution of the bird flock. In order to balance the global search ability and local detection ability of the algorithm in the optimization process, the period time of the birds flying to another area was dynamically adjusted. The weighting strategy of adaptive cosine function and weighted averaging idea were introduced to improve the producer's foraging formula, so as to increase the ability of the algorithm to get rid of difficulties after falling into local optimum. The performance of improved bird swarm algorithm based on mixed decision-making, bird swarm algorithm and particle swarm optimization were compared on the basis of nine test functions. The results showed that the accuracy and speed of the improved algorithm were greatly improved in the test of single-peak and multi-peak functions.
 Select Prediction method of wind power and PV ramp event based on deep learning Zhixiang LIANG,Xiaoming LIU,Ying MU,Yutian LIU Journal of Shandong University(Engineering Science)    2019, 49 (5): 24-28.   DOI: 10.6040/j.issn.1672-3961.0.2019.132 Abstract （979）   HTML （17）    PDF（pc） （1178KB）（500）       Save With the gradual increase of the renewable energy penetration rate, the ramp event that caused the unbalanced active power occured sometimes, and even a large load loss. Due to the insufficient accuracy of wind power and photovoltaic prediction, there were many operational scenarios to be considered. The time domain simulation could not meet the online assessment requirements. A method based on deep learning was proposed in this paper. Considering the generation unit and tie line adjustment ability, the stacked denoising autoencoder was used to extract each layer feature to train support vector machine. The wind power, photovoltaic and load forecast data, and the power of the tie line at the previous moment were taken as inputs, and whether the ramp event occured as an output. The vector machine was used to quickly predict whether a ramp event occured. The simulation results of practical power grid showed that the proposed method was fast and accurate. It could effectively identify ramp events.
 Select A robot service recognition mechanism based on ontology in smart home Linglong KONG,Guohui TIAN Journal of Shandong University(Engineering Science)    2019, 49 (6): 45-54.   DOI: 10.6040/j.issn.1672-3961.0.2018.495 Abstract （656）   HTML （3）    PDF（pc） （5046KB）（479）       Save In order to enhance the ability of robots to provide different types of services, a classification service reasoning method based on semantic web rule language was proposed for service robots in smart home environments. The ontology model of smart home was established by ontology technology, which integrated data from different data sources and eliminated the heterogeneity between devices. The classification of service types were based on the service characteristics of robot service system in smart home. With historical context information, the service rule bases were set up. The reasoning engine could match the real-time context information and service rules to realize the service reasoning of the robot. The experimental results showed that the robot service reasoning method could achieve different types of service reasoning in smart home environments and further improve the intelligence of the robot service.
 Select Research status and development trend of autonomous cognition and learning of robot manipulation skills Wei WANG,Feng WU,Fengyu ZHOU Journal of Shandong University(Engineering Science)    2019, 49 (6): 11-24.   DOI: 10.6040/j.issn.1672-3961.0.2019.229 Abstract （982）   HTML （24）    PDF（pc） （2077KB）（468）       Save Autonomous cognition and learning of manipulation skills, being one of the most important skills for robots, has been one of the hot issues in the field of robotics research. Combining with the authors' work in the field of robotics, this paper's focus is placed on giving a comprehensive overview of the mainstream modes, methods, algorithms, as well as advantages and disadvantages of different methods in terms of robots' manipulation skill learning. It concludes the challenges faced by autonomous learning and the key issues that need to be addressed for the individual cloud robots learning manipulation skills in the knowledge sharing mode. At the end, a potential solution for the above issues is given, and that is to integrate individual learning mode and shared learning model for the purpose of enhancing autonomous cognition and learning ability for robots.
 Select Design and verification of power system for ECVT hybrid electric city bus Youming TANG,Kun DONG,Yuanwei ZHANG Journal of Shandong University(Engineering Science)    2019, 49 (6): 98-106.   DOI: 10.6040/j.issn.1672-3961.0.2019.072 Abstract （726）   HTML （9）    PDF（pc） （2354KB）（463）       Save Aiming at the problem that the integrated starter/generator(ISG) hybrid power system was not ideal in fuel saving effect, this study selected the electronic continuously variable transmission(ECVT) hybrid power system scheme, which was applied and verified in plug-in hybrid electric city bus. Based on the equivalent lever analysis of the kinematics characteristics of a single planetary line, the parameters of key components of a plug-in ECVT power system were matched and calculated. According to the calibration test data, Matlab/Simulink software was used to establish the engine simulation model, drive motor simulation model and generator simulation model, to build the vehicle simulation model. Under typical urban bus cycle conditions in China, the fuel economy, dynamic performance and pure electric maximum continuous voyage characteristics of the target vehicle were studied, and the road tests of economy and dynamic performance were completed. The results showed that the ECVT hybrid system vehicle designed in this study could achieve fuel saving rate of 57.47% compared with traditional vehicles, and 24.12% higher than ISG hybrid system vehicle. Therefore, the adoption of ECVT hybrid power system for plug-in hybrid city bus was feasible and effective, and had obvious fuel saving effect.
 Select Discussion on emergency control of central air conditioner at large receiving-end grid to cope with HVDC blocking fault Meng LIU,Dingyi CHENG,Wen ZHANG,Hengxu ZHANG,Kuan LI,Guohui ZHANG,Jianjun SU Journal of Shandong University(Engineering Science)    2020, 50 (1): 72-81.   DOI: 10.6040/j.issn.1672-3961.0.2019.201 Abstract （584）   HTML （6）    PDF（pc） （5590KB）（457）       Save The central air conditioner had the potential to cope with the DC blocking fault through emergency control, ensure the safe and stable operation of the receiving-end grid after suffering from large power shortage. The basic principle of the central air conditioner was introduced. On this basis, the physical model of the central air conditioner which included central air conditioning unit, temperature change of frozen inflow and outflow water, heat exchange between the cooling water of the fan coil and the room, indoor average temperature change as well as the proportion of the room in the open state were established. An emergency control strategy for direct power cut and flexible recovery of central air conditioning was proposed. The feasibility of the emergency control of the central air conditioning system in response to stability control and under frequency/voltage load shedding were discussed respectively. The characteristics of the central air conditioning emergency control were simulated. The emergency control of central air conditioner was simulated after HVDC blocking fault occurs in Shandong power grid, verifying that the power grid frequency could be increased by 0.04 Hz when central air conditioners accounted for 1% of the total load in Shandong power grid.
 Select Key frame extraction based on ViBe algorithm for motion feature extraction Qiuling LI,Baomin SHAO,Lei ZHAO,Zhen WANG,Xue JIANG Journal of Shandong University(Engineering Science)    2020, 50 (1): 8-13.   DOI: 10.6040/j.issn.1672-3961.0.2019.276 Abstract （966）   HTML （14）    PDF（pc） （4029KB）（446）       Save Aiming at the fact that the background was dominant in the key frame extraction algorithm, in which the foreground target was too small and it was not easy to extract the features of moving targets in sports video, a key frame extraction algorithm for foreground moving target feature extraction based on background modeling algorithm was proposed, which was called visual background extractor (ViBe) algoritm. The foreground target detection of video sequence was firstly carried out using ViBe algorithm, afterwards the scale-invariant feature transformation (SIFT) features of the foreground moving target were extracted. Based on the similarity calculated from video frame series, the key frames of video were output according to the key frame discrimination method. The experimental results showed that the proposed algorithm could solve the problem of missed selection and misselection in traditional key frame extraction. Compared with the algorithm based on SIFT distribution histogram, the F1 score was well improved. The algorithm based on ViBe could effectively identify key frames in sports video.
 Select GRU-based collaborative filtering recommendation algorithm with active learning Delei CHEN,Cheng WANG,Jianwei CHEN,Yiyin WU Journal of Shandong University(Engineering Science)    2020, 50 (1): 21-27,48.   DOI: 10.6040/j.issn.1672-3961.0.2019.411 Abstract （808）   HTML （16）    PDF（pc） （1435KB）（438）       Save The traditional collaborative filtering recommendation algorithm failed to reflect short-term user interest. In order to reflect the short-term interests of users better, a collaborative filtering recommendation algorithm based on Gated Recurrent Unit (GRU) neural network with active learning was proposed. Based on the GRU neural network, the algorithm processed the data into time-series data to reflect the change of the user's interest and used active learning to sample high-quality data dynamically for accelerating the training of GRU neural network. The result on MovieLens1M dataset showed that the GRU model with active learning could obtain higher short-term prediction success rate, recall rate, item coverage, and user coverage compared with the user-based collaborative filtering method (UCF), the markovian chain model-based collaborative filtering method (MC) and the matrix factory-based collaborative filtering method (LFM), so it could effectively predict the short-term interest of users, improve the accuracy, discover the long-tail items. Meanwhile, it could achieve the same effect with fewer iterations compared with the original GRU model.
 Select Bi-level optimal configuration of energy storage system in an active distribution network Liyan WANG,Fei WANG,Yongji CAO,Tao ZHANG,Yaxin ZHANG,Yi LU,Zihan LIU Journal of Shandong University(Engineering Science)    2019, 49 (5): 37-43, 51.   DOI: 10.6040/j.issn.1672-3961.0.2019.082 Abstract （648）   HTML （2）    PDF（pc） （3422KB）（424）       Save In order to optimize the configuration of energy storage system in an active distribution network, a bi-level optimization method was proposed, considering the impact of operation strategy on planning scheme. In the short-scale inner optimization, the high-frequency components of integration power was extracted by the low-pass filtering algorithm. And a multi-objective optimization model was constructed to minimize the variation coefficient of extracted high-frequency component and the rate of the loss of renewable energy, which was simplified into a scalar optimization problem and solved by the particle swarm optimization algorithm. In the long-scale outer optimization, a multi-objective optimization model was established to minimize the investment cost and the rate of the loss of renewable energy, of which the Pareto optimal solutions were searched by the NSGA-Ⅱ. The location and capacity of energy storage system and the rate of the loss of renewable energy were taken as coupling variables, based on which the inner and outer models with different time scales were solved in a united optimization frame. The case study validated the effectiveness of the proposed model and corresponding solving methods, of which the results indicate that the optimal configuration of energy storage system in an active distribution network could enhance the accommodation ability of renewable energy.
 Select The composite control of backstepping control based on uncertain model compensation of wheeled mobile robot Meizhen LIU,Fengyu ZHOU,Ming LI,Yugang WANG,Ke CHEN Journal of Shandong University(Engineering Science)    2019, 49 (6): 36-44.   DOI: 10.6040/j.issn.1672-3961.0.2019.236 Abstract （669）   HTML （4）    PDF（pc） （4106KB）（409）       Save Given these factors of model uncertainty, non-linearity and unmodeled dynamic characteristics existing in wheeled mobile robots, which seriously affected the stability and accuracy of trajectory tracking, a backstepping composite control strategy based on model uncertainty compensation was proposed. Based on the kinematics model of a nonholonomic wheeled mobile robot, backstepping control and Lyapunov stability criterion were adopted to design virtual velocity control quantity as continuous incentive input for trajectory tracking. Considering the model uncertainty and external bounded moment disturbance of wheeled mobile robots, the uncertainties of the system were derived from the dynamic model of wheeled mobile robots, and the moment control quantity of model was acquired by using the neural network with highly nonlinear fitting characteristics, and then adaptive law of uncertainties was obtained from Lyapunov stability analysis to realize self-adjustment and real-time trajectory tracking. The simulation results showed that the proposed composite control strategy could track the reference trajectory adaptively, and had better robustness and tracking accuracy than the single backstepping control strategy, model uncertainty compensation control strategy and PID controller.
 Select Flow characteristics of rough rock fractures under wide range of Reynolds numbers Jie LIU,Zhechao WANG,Yupeng ZHANG,Huayang SUN Journal of Shandong University(Engineering Science)    2019, 49 (4): 70-77, 85.   DOI: 10.6040/j.issn.1672-3961.0.2018.533 Abstract （843）   HTML （11）    PDF（pc） （6754KB）（404）       Save Through experiments and theoretical analysis, the flow characteristics of rock rough fractures with different geometric parameters were studied, including non-Darcy coefficient β, critical Reynolds number Rec and non-Darcy effect factor E. Testing equipment for fluid flow in fractures was developed and 9 rough single fracture models with different apertures and Joint Roughness Coefficients (JRC) were prepared. Laboratory tests on flow in rough fractures with Reynolds numbers, i.e., from 2 to 5000 were performed. The characteristics of flow in single fractures with different roughness (JRC=2-20) under wide range of Reynolds numbers were obtained. It was shown that fracture roughness had a significant impact on the nonlinear flow characteristics of the fracture. Based on the Forchheimer equation, the effects of fracture roughness on equation parameters were quantitatively studied. The larger fracture roughness was, the more likely it was to cause the nonlinearity of the fracture flow, the smaller critical Reynolds number was, and the stronger non-linear effect would be.
 Select The influence of shape parameters of wave energy device floating body on energy capture characteristics Yanjun LIU,Wei WANG,Zhi CHEN,Donghai WANG,Dengshuai WANG,Gang XUE Journal of Shandong University(Engineering Science)    2020, 50 (6): 1-8,16.   DOI: 10.6040/j.issn.1672-3961.0.2020.160 Abstract （527）   HTML （147）    PDF（pc） （6369KB）（401）       Save To clarify the effect of the floating body′s shape parameters on the energy capture performance and working stability, an oscillating float type wave energy converter (WEC) model with linear power take-off system was established. Frequency domain calculation theory was used to deduce the formulas of energy capture power and energy capture width ratio. After introducing the numerical simulation steps of floating body in frequency domain, ANSYS-AQWA software was used to investigate the floater's energy capture power and energy capture width ratio with different bottom shapes and half vertex angles. Influence of shape parameters on the energy capture performance was drawn to provide a theoretical basis for the shape optimization of the floating body applied to the wave power supply device and floating platform. The results showed that the practical fabrication feasibility of circular truncated cone bottom was higher than that of cone and sphere. The energy capture characteristics and stability of circular truncated cone bottom were better than that of general cylindrical floating body in the intermediate wave frequency band. The energy capture performance and working stability of circular truncated cone floating body with big top and small bottom were better. The energy capture performance under intermediate frequency waves could be improved with the increase of the half vertex angle. The optimal power capture performance and working stability could be achieved with a proper apex angle.
 Select TBM comprehensive advanced geological prediction in a tunnel andits application in Yangling Tunnel Jun LIU,Lijun HAN,Qingbin MENG Journal of Shandong University(Engineering Science)    2019, 49 (4): 51-60.   DOI: 10.6040/j.issn.1672-3961.0.2018.093 Abstract （873）   HTML （5）    PDF（pc） （5462KB）（385）       Save Advanced geological prediction was used to play an irreplaceable role in the aspect of informative tunnel construction, effective disaster prevention, economical construction support in tunnel engineering. The effectiveness of the advanced geological prediction method in the drilling and blasting method under the tunnel boring machine (TBM) specific construction environment was compared and analyzed. The comprehensive advanced geological prediction system under TBM tunnel construction with "long and short distance, geophysical and drilling exploration, sound wave reflection and electromagnetic method, key and normal" was established. Based on the horizontal sonic profiling (HSP) sound wave reflection, drilling process monitoring (DPM) advanced drilling, transient electromagnetic instrument, the multiple solutions and error superposition of single advanced geological prediction method were suppressed effectively. And then the 3D forward theory calculation was considered as an appropriate way for enhancing the accuracy and reliability. Based on the law of electromagnetic response and the study of removing electromagnetic interference, the results summarized from the paper were used to guide the application of transient electromagnetic method in Yixing Yangling Tunnel and to provide a reference for future projects.
 Select Weak signal detector based on all-digital phase-shifting lock-in method Lu WANG,Hong WANG,Guoping CHEN Journal of Shandong University(Engineering Science)    2019, 49 (4): 24-28.   DOI: 10.6040/j.issn.1672-3961.0.2018.526 Abstract （668）   HTML （3）    PDF（pc） （3505KB）（385）       Save In order to solve the problem of the uncontrollable phase difference in existing lock-in detection and the vulnerable to interference or high power consumption in analog phase-shifting circuit. The lock-in detection equipment based on all-digital phase-shifting method was designed, which the analog correlation signal was replaced by an all-digital reference signal with frequency traversal and co-frequency shift, then combined with the lock-in correlation detection to extract weak signals in low SNR. The reference signal and the weak signal to be tested were transmitted by direct memory access(DMA), the analog to digital converter(ADC) and digital to analog converter(DAC) were used to realize the transmission of synchronous frequency data with low power and faster transfer speed. The results showed that the lowest SNR detectable by this method was -46 dB with good stability and efficiency in a strong noise environment of 90 dB. It had great practical value for high-precision quality testing in high noise environment passive speaker equipment of the industrial plant.
 Select Heat transfer performance analysis of phase change energy storage heat exchanger based on entransy theory Xinchen ZHOU,Xuelai ZHANG,Yue CHEN,Lu LIU Journal of Shandong University(Engineering Science)    2019, 49 (5): 72-84.   DOI: 10.6040/j.issn.1672-3961.0.2019.151 Abstract （623）   HTML （9）    PDF（pc） （4434KB）（385）       Save Entransy transfer efficiency, entransy dissipation number and thermal resistance of heat exchanger based on entransy dissipation were applied to heat transfer performance analysis of phase change energy storage heat exchanger on the basis of successful application of entransy theory on conventional heat exchanger. The generalized entransy dissipation rate was defined to derive (instantaneous) entransy transfer efficiency of phase change energy storage heat exchanger in heat storage, heat release and total process, and heat transfer rate was determined to calculate entransy dissipation number and thermal resistance of heat exchanger based on entransy dissipation. A kind of phase change energy storage heat exchanger was selected as the object, and the temperature variation of main parts were described by theoretical analyses. The temperature variation of outlet of silicon oil and water were further simplified to derive their expression, as the basis of calculation and analyses. The results showed that the application range of entransy transfer efficiency was the widest, which was used to calculate the (instantaneous) irreversible heat loss of phase change energy storage heat exchanger in heat storage, heat release and total process. The evaluation results of entransy transfer efficiency were consistent with heat transfer performance and its instantaneous values were increased first, then unchanged, finally increased, with increasing heat storage time, and were decreased first, then unchanged, finally decreased, with increasing heat release time. The evaluation results of entransy dissipation number in heat storage and total process were consistent with that of entransy transfer efficiency. With increasing heat storage time, its instantaneous values were decreased first, then unchanged, finally decreased, while its application was limited in heat release process. The application of thermal resistance of heat exchanger based on entransy dissipation was the most limited since parts of its evaluation results were inconsistent with actual state. In heat storage and total process, the entransy transfer efficiency, entransy dissipation number and thermal resistance of heat exchanger based on entransy dissipation were nearly unchangeable when the heat storage quantity, heat release quantity and stage time in the process of heat storage and release were synchronous. The entransy transfer efficiency was increased, while the entransy dissipation number and the thermal resistance of heat exchanger based on entransy dissipation were decreased when the heat transfer efficiency was improved. In the heat release process, entransy transfer efficiency was unchangeable since the heat transfer performance of system was not influenced by the change of parameters setted.
 Select Bridge monitoring and warning system based on digital measurement technology Chengxin YU,Guojian ZHANG,Yongqian ZHAO,Xiaodong LIU,Xinhua DING,Tonglong ZHAO Journal of Shandong University(Engineering Science)    2020, 50 (1): 115-122.   DOI: 10.6040/j.issn.1672-3961.0.2019.063 Abstract （780）   HTML （11）    PDF（pc） （3123KB）（377）       Save In order to make up the deficiency of the traditional measuring method in monitoring the whole deformation and real-time monitoring of the bridge and overcome the defect of digital photography in monitoring the three-dimensional deformation of a bridge, this paper presented the image matching-time baseline parallax method: a digital camera was set up in the proper place, and a reference plane, consisting of reference points, was not far from the digital camera. Reference plane was perpendicular to the photographic direction, and the monitoring points were on the bridge. The two-dimensional deformation on the object plane of the deformation point was obtained based on image matching-time baseline parallax method, then the horizontal deformation on object plane was disassembled into the bridge direction and the direction perpendicular to bridge direction based on the principle of three-dimensional deformation monitoring, The three-dimensional deformation of the bridge was got. Results showed that measurement accuracy of the bridge was 0.72 mm and 1.16 mm in X and Z direction on object plane, respectively. It could meet accuracy requirements of deformation monitoring. As Phoenix mountain road-bridge showed good flexibility in X, Y, Z and comprehensive direction, and the absolute of the maximum positive and negative deflection was 7.57 mm, which was approximately equal to 1/8 of the allowable deflection of the bridge (L/1 000), and the bridge was in good health. Bridge health monitoring and warning system could achieve the integration of data acquisition, storage, processing and display. The deformation curves could show the deformation trend of the bridge and effectively warn the potential danger.
 Select Transmission network reconfiguration strategy based on preference multiobjective optimization and genetic algorithm Runjia SUN,Hainan ZHU,Yutian LIU Journal of Shandong University(Engineering Science)    2019, 49 (5): 17-23.   DOI: 10.6040/j.issn.1672-3961.0.2019.123 Abstract （635）   HTML （4）    PDF（pc） （4095KB）（373）       Save This paper proposed a transmission network reconfiguration strategy based on preference multiobjective optimization and genetic algorithm, which incorporated the preferences for different objectives to obtain network reconfiguration schemes. Considering the factors about generators, transmission lines and loads, three objectives were proposed to establish a preference multiobjective optimization model. Considering the preference and discreteness of the model, a preference-based nondominated sorting genetic algorithm Ⅱ was designed. To improve the solve efficiency, the preference-based dominance relation, population sacle control technique and repetitive individual filtration technique were proposed to obtain a preference Pareto solution set with a controllable number of solutions. The simulation results demonstrated that the strategy could reasonably leverage the tradeoff among different factors about network reconfiguration, and the proposed algorithm was highly efficient in solving network reconfiguration optimization problems.
 Select An ensemble learning algorithm for unbalanced data classification Zongtang ZHANG,Sen WANG,Shilin SUN Journal of Shandong University(Engineering Science)    2019, 49 (4): 8-13.   DOI: 10.6040/j.issn.1672-3961.0.2019.050 Abstract （1048）   HTML （11）    PDF（pc） （1159KB）（359）       Save For unbalanced data classification problem in underwater acoustic target recognition, a random subspace AdaBoost algorithm called RSBoost was proposed. Subtraining sample set was extracted by random subspace method in different underwater acoustic feature space and base classifier was trained in every subtraining sample set. The base classifier with the maximum margin mean of minority class was chosen as the base classifier of this round, the final ensemble classifier was formed iteratively. The experiment was carried out on the measured data, the performance of RSBoost and AdaBoost in different feature space was evaluated by F-measure and G-mean. The results showed that, compared with AdaBoost, the F-measure of RSBoost improved from 0.07 to 0.22 and the G-mean improved from 0.18 to 0.25, which showed that RSBoost was superior to AdaBoost in underwater acoustic unbalanced classification problem.
 Select Analysis of factors affecting heat transfer of double U-shaped buried tubes based on TRNSYS Tao LIU,Ye TIAN,Yongzhi MA Journal of Shandong University(Engineering Science)    2019, 49 (6): 113-118.   DOI: 10.6040/j.issn.1672-3961.0.2019.317 Abstract （705）   HTML （6）    PDF（pc） （1908KB）（349）       Save Because the horizontal buried tubes covered a large area, the heat transfer effect was poor, and the initial investment of the vertical buried tubes was high, the construction was difficult. A transient real-time simulation model of double U-shaped buried tubes heat exchanger was established with TRNSYS software. The factors, which could affect the heat transfer capacity of double U-shaped buried tubes heat exchanger, including the number and the spaceing of holes, and the depth of the buried tubes were analyzed under the condition of unique variable. The simulation experiment results showed that the heat transfer effect of buried tubes could be improved by increasing the number of holes, deepening drilling depth and increasing the spacing of the holes. It provided an analytical basis for the balance between the heat transfer effect of the buried tubes and the construction difficulty.
 Select Configuration design and interference analysis of multi-arm robot for mandible reconstruction Honghua ZHAO,Jian ZHAO,Xingguang DUAN,Zhitong HU,Qianqian TIAN,Yaohua ZHAO Journal of Shandong University(Engineering Science)    2019, 49 (6): 73-80.   DOI: 10.6040/j.issn.1672-3961.0.2019.185 Abstract （668）   HTML （3）    PDF（pc） （5769KB）（347）       Save Based on the requirements of mandible reconstruction surgery and the design criteria of surgical robots, a seven degree of freedom three-arm configuration with active and passive combination was proposed. In order to meet the requirement of high efficiency of interference analysis for manipulator of surgical robot, the linear swept sphere element model was used to simplify the manipulator with complex structure. The interference mathematical models between two cylinders, between cylinders and hemispheres, and between two hemispheres were constructed. The concept of effective interference points and the method of judging the effectiveness of interference points were proposed. The interference judgment of the manipulator at any position was obtained. The experiment of non-interference control verified the correctness of the method by robot platform. The method simplified the criterion and process of interference analysis of basic geometric model, reduced the number of interference judgments between models, and improved the efficiency of interference analysis.
 Select Visualization of interactive ThemeRiver based on time-series data Xindi CHEN,Tianrui LI,Huanhuan YANG Journal of Shandong University(Engineering Science)    2019, 49 (4): 29-35, 43.   DOI: 10.6040/j.issn.1672-3961.0.2017.400 Abstract （974）   HTML （16）    PDF（pc） （3445KB）（341）       Save ThemeRiver was a widely used technique when visualizing time-series data, which showed the whole trend efficiently. But the user often encountered ambiguity when observing a single river due to the influence of the lower river. However, the current visualization technique couldn't solve the issue. The following improvements of ThemeRiver were proposed upon the above issue: The river fluctuation was evaluated by the coefficient of variance instead of standard deviation, and the rivers with smaller fluctuation were arranged in lower position in order to reduce the impact on the upper rivers; The concept of ambiguity point was proposed, and the user could set fluctuation and max contribution as filtering parameters in the user interface so that the ambiguity points would be dynamically displayed by the system; The ambiguity point was visualized as bellow(The peak and valley of a river were represented by triangle and inverted triangle, respectively; The triangles would be filled with the color of the river with max contribution; A reorderable interactive ThemeRiver was proposed, in which the user was able to reorder the rivers by dragging them according to the information given by the ambiguity points). The proposed method was applied on the data containing 20 themes of 2015 from Zhihu and the results showed that the system could efficiently eliminate the ambiguity of ThemeRiver when presenting the trend of a single river and provided a flexible and personalized visualization.
 Select A force-based method for robot hole-searching and assembly Yujun WU,Wei WU,Yu GUO,Jian GUO Journal of Shandong University(Engineering Science)    2019, 49 (5): 119-126.   DOI: 10.6040/j.issn.1672-3961.0.2018.396 Abstract （874）   HTML （12）    PDF（pc） （7332KB）（337）       Save In the process of replacing arresters for live working robots, a method based on force control for robot to search hole on insulated cross-arms and assembling arresters was proposed for accurate assembly. In the control process, a force sensor was installed at the end of the robot for the special shape of the arrester's lower end and the scene of the pole cross arm, and the converted force was used as the controlled amount. A peg-in-hole assembly strategy was designed, which included four processes of touching, hunting, evolving and inserting. The robot could insert the arrester's lower end into the mounting hole on the cross arm accurately. The experimental results verified the effectiveness of the proposed method.
 Select Vehicle classification and tracking for complex scenes based on improved YOLOv3 Shiqi SONG,Yan PIAO,Zexin JIANG Journal of Shandong University(Engineering Science)    2020, 50 (2): 27-33.   DOI: 10.6040/j.issn.1672-3961.0.2019.412 Abstract （833）   HTML （16）    PDF（pc） （5481KB）（335）       Save Aiming at the influence of weather conditions and mutual occlusion of vehicles on vehicle classification and tracking accuracy and stability, a hybrid model based on improved YOLOv3 and matching tracking was proposed. The improved YOLOv3 network refered to DenseNet′s design idea, replaced the residual layer in the network with a dense convolution block and changed the design structure of the network. The fused features of dense convolution blocks and convolution layers were classified by using Softmax classifier. According to the detection result of single frame image, the target matching function was designed to solve the vehicle tracking problem in video sequence. In the KITTI dataset test, the improved algorithm achieved an average precision of 93.01%, the number of frames per second reached 48.98, and the average recognition rate in the self-built dataset was 95.79%. The experimental results showed that the proposed method could effectively distinguish the types of vehicles in complex scenes with higher accuracy. At the same time, the method had higher accuracy and robustness in vehicle tracking.
 Select Pollution characteristics and atmospheric transmission of PM2.5 and PM1.0 in Jinan city Qi HUANG,Lingxiao YANG,Yanyan LI,Pan JIANG,Ying GAO,Wenxing WANG Journal of Shandong University(Engineering Science)    2020, 50 (1): 95-100, 108.   DOI: 10.6040/j.issn.1672-3961.0.2019.001 Abstract （643）   HTML （5）    PDF（pc） （3561KB）（313）       Save To study the characteristics of PM2.5 and PM1.0 in the North China Plain, atmospheric particulate samples were collected from October, 2014 to June, 2016 in Jinan urban area by using mid-volume samplers. Then we determined iron composition of Water-soluble inorganic ions with ion chromatography(IC)and carbonaceous component with thermal-optical transmittance (TOT) carbon aerosol analyzer. It was shown that the fine particle pollution of the atmosphere was serious in winter. The secondary ions SO42-, NO3- and NH4+ were the major water-soluble ions of PM2.5 and PM1.0, especially easily enriched in PM1.0. Compared with autumn and winter, concentrations of organic carbon(OC) and elemental carbon (EC) were much lower in spring and summer. The mass concentration of SOC, most of which was distributed in particles with particle size >1 μm, increased obviously in winter. Indicated by the 72 h backward trajectories, long-distance transmission from Hebei and Inner Mongolia, as well as local transmission from Shan- dong had an important influence on the ion mass concentration of PM2.5 and PM1.0 in the atmosphere of Jinan. The extinction coefficient of Jinan was up to 789.13 Mm-1 in winter. The extinction coefficient had a high correlation with secondary particles NH4+, SO42- and NO3- in PM2.5, which was the chief reason of the reduction in the visibility of the atmosphere.
 Select MR image classification and recognition model of breast cancer based onGabor feature Gaoteng YUAN,Yihui LIU,Wei HUANG,Bing HU Journal of Shandong University(Engineering Science)    2020, 50 (3): 15-23.   DOI: 10.6040/j.issn.1672-3961.0.2019.305 Abstract （678）   HTML （12）    PDF（pc） （7621KB）（310）       Save To investigate the clinical value of breast tumor magnetic resonance (MR) images in differentiating fibroadenoma of breast (FB), invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC), the region of interest of MR image was selected and the MR image was decomposed by wavelet transform, and the region of tumor was segmented by K-means algorithm. Gabor wavelet was used to filter the region of interest from 8 directions and 5 scales, and the mean value of the tumor location was taken as the feature. The extracted features were analyzed and the key features were obtained. Different classification algorithms were compared in machine learning, such as support vector machine, Bayesian, and neural network, to classify and predict the key features, and calculate the accuracy, sensitivity and specificity of classification, so as to get the most suitable parameter settings for classification model. Texture analysis of breast MR images could distinguish three kinds of common breast tumors, and the prediction accuracy was 77.36%, which showed that MR image had important clinical value in differentiating FB, IDC and ILC.
 Select Research on BP neural network rainfall runoff forecasting model based on elastic gradient descent algorithm Baoming JIN,Guangyi LU,Wei WANG,Lunyue DU Journal of Shandong University(Engineering Science)    2020, 50 (3): 117-124.   DOI: 10.6040/j.issn.1672-3961.0.2019.504 Abstract （583）   HTML （7）    PDF（pc） （2025KB）（304）       Save The improved elastic gradient descent algorithm of back propagation was used, and 14 rainfall runoff processes from 1997 to 2014 in the upper reaches of Chongyang River were selected. The back propagation (BP) neural network rainfall-runoff forecasting model of the elastic gradient descent algorithm was established, which took the measured rainfall of six rainfall stations in Yangzhuang, Wubian, Da′an, Kengkou, Lingyang, and Langu in the basin and the preliminary flow data of Wuyishan Hydrological Station as inputs, and selected the corresponding flow of Wuyishan Hydrological Station as output. The 7-rainfall runoff process was used to test the model, the test results showed that the proposed method required fewer parameters and had higher operation speed than the traditional back propagation algorithm. The prediction accuracy of the model could meet the requirements, and provide the basis for flood control and disaster reduction.
 Select Lightweight self-adaptive CSI-based positioning algorithm in underground mine Junmei YUE,Dongmei ZHANG Journal of Shandong University(Engineering Science)    2019, 49 (5): 112-118.   DOI: 10.6040/j.issn.1672-3961.0.2018.356 Abstract （677）   HTML （3）    PDF（pc） （2758KB）（298）       Save To solve the problem of high cost and working hazard factor of traditional downhole positioning methods, a lightweight self-adaptive CSI-based positioning algorithm in underground mine was proposed. The fine-grained CSI was used to obtain higher positioning accuracy rather than coarse-grained RSSI, inverse fast Fourier transform was adopted to transform CSI data to channel impulse response so as to get the line-of-sight signal, an attenuation model of line-of-sight signal of CSI was built to implement accurate ranging, position features of existing point access points (APs) in wireless fidelity and characteristics of rock roadways was utilized to calculate orientation of target relative to AP, which finally completed location according to orientation and distance. LSA was adaptive to arbitrary deployment modes, and the corner recognition optimization algorithm was used to improve positioning accuracy. The experimental results showed that LSA method median error could reach 0.53 m and eliminate the need to deploy any positioning system in the well alone, the performance was superrior to CDPF and FILA.
 Select TRCC series system based on LNG cold energy and fuel cellwaste heat utilization Yinglun GUO,Fuqiang XI,Ruizhi SU,Guoxiang LI,Zeting YU Journal of Shandong University(Engineering Science)    2019, 49 (5): 52-57.   DOI: 10.6040/j.issn.1672-3961.0.2019.154 Abstract （715）   HTML （5）    PDF（pc） （1261KB）（292）       Save A cogeneration system based on solid oxide fuel cell (SOFC for short) and transcritical carbon dioxide cycle (TRCC for short) was proposed. The transcritial carbon dioxide cycle was used to recover the exhaust heat of the SOFC while utilizing the LNG refrigeration capacity. The mathematical model of the system was established, and the influence of parameter changes on system performance was analyzed. The results showed that under the design conditions, the thermal efficiencies of SOFC, TRCC, and the whole system were 64.2%, 22.4%, and 74.1%, respectively. The system thermal efficiency increased with the inlet temperature of the fuel cell and decreased with the increase of the steam-carbon ratio. The thermal efficiency increased as the turbine inlet pressure to the TRCC increased.
 Select Impact analysis on construction of large section and small spacing road tunnel Mingcai LIU Journal of Shandong University(Engineering Science)    2019, 49 (4): 78-85.   DOI: 10.6040/j.issn.1672-3961.0.2018.055 Abstract （781）   HTML （4）    PDF（pc） （3052KB）（289）       Save The construction project of Fo Yangling Tunnel was taken as the research background, the construction was carried out by using benching tunneling construction method. The fast Lagrangian analysis of continua 3D (FLAC3D) finite element software was used as the calculation platform to establish the finite element model of tunnel with large section and small clear distance. The tunnel model was numerically simulated and subsidence, stress of surrounding rock and lining structural were analyzed. And the corresponding monitoring and reinforcement measures were put forward. The results of numerical analysis showed that the settlement of the upper part of the advance tunnel was larger than the subsequent tunnel. The construction of the subsequent tunnel increased the vertical displacement of the advance tunnel, which caused the increase of maximum principal stress and the minimum principal stress. The stress of tunnel lining structure was concentrated in the area from arch waist to arch foot. The support structure of advance tunnel played the role of stabilizing rock mass in the excavation of subsequent tunnel, and the excavation of the subsequent tunnel would make the stress concentration of the middle rock. In the construction, attention should be payed to the surrounding rock and reinforcement measures should be taken. The analysis results could provide a scientific basis for the design and construction of large section and small spacing road tunnel.
 Select A syntactic element recognition method based on deep neural network Yanping CHEN,Li FENG,Yongbin QIN,Ruizhang HUANG Journal of Shandong University(Engineering Science)    2020, 50 (2): 44-49.   DOI: 10.6040/j.issn.1672-3961.0.2019.313 Abstract （682）   HTML （7）    PDF（pc） （1711KB）（289）       Save It was difficult to obtain structural information in Chinese sentences by the traditional feature method. To solve the problem, according to characteristics of Chinese sentence, a Bi-LSTM-Attention-CRF model was proposed based on deep neural network. A Bi-LSTM network was used to automatically extract structural information and semantic information from raw input sentences. Attention mechanism was adopted to weight abstract semantic features for classification. An optimized label sequence was output through the CRF layer. Comparing with other methods, our model could effectively identify syntactic elements in sentences. The performance reached to 84.85% in F1 score in the evaluation data sets.
 Select Visual sentiment analysis based on spatial attention mechanism and convolutional neural network Guoyong CAI,Xinhao HE,Yangyang CHU Journal of Shandong University(Engineering Science)    2020, 50 (4): 8-13.   DOI: 10.6040/j.issn.1672-3961.0.2019.422 Abstract （753）   HTML （110）    PDF（pc） （1354KB）（289）       Save Existing visual sentiment analysis based on deep learning mainly ignored the intensity differences of emotional presentation in different parts of the image. In order to solve this problem, the convolutional neural network based on spatial attention (SA-CNN) was proposed to improve the effect of visual sentiment analysis. The affective region detection neural network was designed to discover the local areas of sentiment induced in images. The spatial attention mechanism was used to assign attention weights to each location in the sentiment map, and the sentiment features of each region were extracted appropriately, which was helpful for sentiment classification by using local information. The discriminant visual features were formed by integrating local region features and global image features, and were used to train the neural network classifier of visual sentiment. Classification accuracy of the method achieved 82.56%, 80.23% and 79.17% on three real datasets Twitter Ⅰ, Twitter Ⅱ and Flickr, which proved that the method could improve the visual emotion classification effect by making good use of the difference of emotion expression in the local area of the image.


text:
# Quotient rule and binomial theorem

1. Nov 18, 2013

### Jhenrique

If it's possible to relate the product rule with the binomial theorem, so:

$$(x+y)^2=1x^2y^0+2x^1y^1+1x^0y^2$$
$$D^2(fg)=1f^{(2)}g^{(0)}+2f^{(1)}g^{(1)}+1f^{(0)}g^{(2)}$$

So, is it possible to relate the quotient rule with the binomial theorem too?

2. Nov 18, 2013

### Jorriss

3. Nov 18, 2013

### Staff: Mentor

I don't think so.

4. Nov 19, 2013

### HallsofIvy

Write $f/g$ as $fg^{-1}$ and apply the product rule to that.

format: plain


text:
CoCalc Public Filesprojects_F20 / rec_Proj6 / recursion.ipynb
Author: Julia Burnside
Views : 30
Compute Environment: Ubuntu 20.04 (Default)

## Recursive Conversion from List to Integers

An empty array called $list$ is declared. The user is prompted to enter a sequence of single digit integers between $1$ and $9$. Each integer entered will append the length of $list$ and be added to the array. $-1$ is assigned as the command value to quit the process and proceed to converting the values in $list$ to an integer.

The function $rec\_int$ takes a single parameter, $list$. First, the function evaluates the length of $list$. If the length is $1$, meaning there is only a single value in the array, then the function returns that value at $list[0]$. Otherwise, the function will take the value at $list[0]$ and multiply it by $10$ to the power of the length of the array, minus $1$. So, for example, if the array is of length $3$ and the first value is $2$, this process will yield $2*10^{3-1}=2*10^2=2*100=200$. To add the remaining values in the array, the function is then called recursively with the appendment of slicing the array to $list[1:]$. This precludes the first value of the array and also appends the length of $list$. The function will continue to iterate through this process until the length of $list=1$, which will then yield the final value of the list transformed into an integer.

In [8]:
list=[]

print("Enter a list of single digit integers, or -1 to quit and proceed to conversion", '\n')
x=int(input())
while (x!=-1):
if (x<0 or x>9):
print("invalid entry. Enter a single digit integer", '\n')
else:
list.append(x)
x=int(input())

def rec_int(list):
if len(list) == 1:
return list[0]
else:
return list[0]*(10**(len(list)-1))+(rec_int(list[1:]))

print(rec_int(list))

Enter a list of single digit integers, or -1 to quit and proceed to conversion


text:
## CSDN博客

### 2 词法约定 【词法】

#### 2.7 注释 【词法.注释】

The characters /* start a comment, which terminates with the characters */. These comments do not nest. The characters // start a comment, which terminates with the next new-line character. If there is a form-feed or a vertical-tab character in such a comment, only white-space characters shall appear between it and the new-line that terminates the comment: no diagnostic is required. [Note: The comment characters //, /*, and */ have no special meaning within a // comment and are treated just like other characters. Similarly, the comment characters // and /* have no special meaning within a /* comment. ]

PREV [lex.token] | NEXT [lex.header] 上一页 【词法.标记】 | 下一页 【词法.头】
0 0


text:
# python – How to state in requirements.txt a direct github source

## The Question :

502 people think this question is useful

I’ve installed a library using the command

pip install git+git://github.com/mozilla/elasticutils.git

which installs it directly from a Github repository. This works fine and I want to have that dependency in my requirements.txt. I’ve looked at other tickets like this but that didn’t solve my problem. If I put something like

-f git+git://github.com/mozilla/elasticutils.git
elasticutils==0.7.dev

in the requirements.txt file, a pip install -r requirements.txt results in the following output:

Downloading/unpacking elasticutils==0.7.dev (from -r requirements.txt (line 20))
Could not find a version that satisfies the requirement elasticutils==0.7.dev (from -r requirements.txt (line 20)) (from versions: )
No distributions matching the version for elasticutils==0.7.dev (from -r requirements.txt (line 20))

The documentation of the requirements file does not mention links using the git+git protocol specifier, so maybe this is just not supported.

Does anybody have a solution for my problem?

363 people think this answer is useful

“Editable” packages syntax can be used in requirements.txt to import packages from a variety of VCS (git, hg, bzr, svn):

-e git://github.com/mozilla/elasticutils.git#egg=elasticutils

Also, it is possible to point to particular commit:

-e git://github.com/mozilla/elasticutils.git@000b14389171a9f0d7d713466b32bc649b0bed8e#egg=elasticutils

511 people think this answer is useful

Normally your requirements.txt file would look something like this:

package-one==1.9.4
package-two==3.7.1
package-three==1.0.1
...

To specify a Github repo, you do not need the package-name== convention.

The examples below update package-two using a GitHub repo. The text between @ and # denotes the specifics of the package.

## Specify commit hash (41b95ec in the context of updated requirements.txt):

package-one==1.9.4
git+git://github.com/path/to/package-two@41b95ec#egg=package-two
package-three==1.0.1

## Specify branch name (master):

git+git://github.com/path/to/package-two@master#egg=package-two

## Specify tag (0.1):

git+git://github.com/path/to/package-two@0.1#egg=package-two

## Specify release (3.7.1):

git+git://github.com/path/to/package-two@releases/tag/v3.7.1#egg=package-two

Note that #egg=package-two is not a comment here, it is to explicitly state the package name

This blog post has some more discussion on the topic.

188 people think this answer is useful

requirements.txt allows the following ways of specifying a dependency on a package in a git repository as of pip 7.0:1

[-e] git+git://git.myproject.org/SomeProject#egg=SomeProject
[-e] git+https://git.myproject.org/SomeProject#egg=SomeProject
[-e] git+ssh://git.myproject.org/SomeProject#egg=SomeProject
-e git+git@git.myproject.org:SomeProject#egg=SomeProject (deprecated as of Jan 2020)

For Github that means you can do (notice the omitted -e):

git+git://github.com/mozilla/elasticutils.git#egg=elasticutils

I got somewhat confused by the -e flag in the other answers so here’s my clarification:

The -e or --editable flag means that the package is installed in <venv path>/src/SomeProject and thus not in the deeply buried <venv path>/lib/pythonX.X/site-packages/SomeProject it would otherwise be placed in.2

Documentation

87 people think this answer is useful

First, install with git+git or git+https, in any way you know. Example of installing kronok‘s branch of the brabeion project:

pip install -e git+https://github.com/kronok/brabeion.git@12efe6aa06b85ae5ff725d3033e38f624e0a616f#egg=brabeion

Second, use pip freeze > requirements.txt to get the right thing in your requirements.txt. In this case, you will get

-e git+https://github.com/kronok/brabeion.git@12efe6aa06b85ae5ff725d3033e38f624e0a616f#egg=brabeion-master

Third, test the result:

pip uninstall brabeion
pip install -r requirements.txt

18 people think this answer is useful

Since pip v1.5, (released Jan 1 2014: CHANGELOG, PR) you may also specify a subdirectory of a git repo to contain your module. The syntax looks like this:

pip install -e git+https://git.repo/some_repo.git#egg=my_subdir_pkg&subdirectory=my_subdir_pkg # install a python package from a repo subdirectory

Note: As a pip module author, ideally you’d probably want to publish your module in it’s own top-level repo if you can. Yet this feature is helpful for some pre-existing repos that contain python modules in subdirectories. You might be forced to install them this way if they are not published to pypi too.

3 people think this answer is useful

Github has a zip endpoint that in my opinion is preferable to using the git protocol. The advantages are:

• You don’t have to specify #egg=<project name>
• Git doesn’t need to be installed in your environment, which is nice for containerized environments
• It works much better with pip hashing
• The URL structure is easier to remember and more discoverable

You usually want requirements.txt entries to look like this, e.g. without the -e prefix:

https://github.com/org/package/archive/1a58aa586efd4bca37f2cfb9d9348958986aab6c.zip

To install from main branch:

https://github.com/org/package/archive/main.zip

2 people think this answer is useful

I’m finding that it’s kind of tricky to get pip3 (v9.0.1, as installed by Ubuntu 18.04’s package manager) to actually install the thing I tell it to install. I’m posting this answer to save anyone’s time who runs into this problem.

Putting this into a requirements.txt file failed:

git+git://github.com/myname/myrepo.git@my-branch#egg=eggname

By “failed” I mean that while it downloaded the code from Git, it ended up installing the original version of the code, as found on PyPi, instead of the code in the repo on that branch.

However, installing the commmit instead of the branch name works:

git+git://github.com/myname/myrepo.git@d27d07c9e862feb939e56d0df19d5733ea7b4f4d#egg=eggname


text:
# Android Property Animations: Evaluators

Until now we have been animating float or int properties only. The Property Animation System is, however, not limited to only simple numeric types. Out of the box, you can also animate ARGB colours and Rect objects by using the ArgbEvaluator and the RectEvaluator classes. In fact, you can animate any kind of object if you write your own evaluator class. In this post I will be showing a few examples and explain how to use evaluators to animate other object types. To provide examples, I will create two evaluators. The first will animate between two Matrix transformations. The second will animate between two colours using the HSV colour model.

### Using Evaluators

In the previous examples we created object animators by calling the static methods ObjectAnimator.ofFloat and ObjectAnimator.ofInt. These two methods return object animators that are set up to animate float and int properties of an object. Implicitly the animators will use the FloatEvaluator and the IntEvaluator classes. These classes will convert a floating point number, usually in the range between 0.0 and 1.0 to a float or int that lies between the start point and end point of the animation. In other words, the evaluator takes an input value from the output of the interpolator and converts it into the type that the animated object can understand.

Android has two other evaluators built in. The RGBEvaluator can be used to set colour properties of objects. The RectEvaluator, which is available since API version 18 is used to animate Rect properties. To create an object animator that animates a Rect or colour property we can use the ObjectAnimator.ofObject method. This method is very similar to the  ObjectAnimator.ofFloat and ObjectAnimator.ofInt methods. The only difference is that we have to pass the evaluator explicitly.

Let’s create a colour animation by animating the background colour of a View from red to blue.

View someView = findViewById(R.id.some_view);

ObjectAnimator anim = ObjectAnimator.ofObject(someView,
"backgroundColor",
new ArgbEvaluator(),
Color.RED, Color.BLUE);

anim.setDuration(2000);
anim.start();

Animation using the RGBEvaluator

The only line that is new compared to previous tutorials is the second line. ObjectAnimator.ofObject takes the evaluator as third argument. The fourth and the following arguments specify the values that the animator should take as start value, end value and the values of any way points between the start and end. You can specify an arbitrary number of values to animate through, as described in the tutorial on programming animations. The RGBEvaluator will separate the colours into their red, green and blue components. These will be animated separately. The result can be seen on the right.

As an example of using the RectEvaluator, we will animate the clipBounds property of an ImageView. Note that the RectEvaluator is only available from API 18 onwards so you should set your minSdkVersion in the manifest accordingly.

View someImage = findViewById(R.id.some_image);
Rect local = new Rect();
someImage.getLocalVisibleRect(local);
Rect from = new Rect(local);
Rect to = new Rect(local);

from.right = from.left + local.width()/4;
from.bottom = from.top + local.height()/2;

to.left = to.right - local.width()/2;
to.top = to.bottom - local.height()/4;

To create an animation using rectangle values we need to define some rectangles for the start and end values of the simulation We first obtain the Rect that describes the visible part of the ImageView. This is done by creating a Rect called local and then passing it to getLocalVisibleRect. The two rectangles from and to are created as copies of the local rectangle. The bounds of from and to are changed so that from sits in the top left hand corner of the view and to sits in the bottom right hand corner.

ObjectAnimator anim = ObjectAnimator.ofObject(someImage,
"clipBounds",
new RectEvaluator(),
from, to);

anim.setDuration(2000);
anim.start();

Animation using RectEvaluator

Creating the ObjectAnimator is again just a call to ObjectAnimator.ofObject. This time we pass a new RectEvaluator as third argument. The two Rect objects from and to are passed as fourth and fifth argument.

When the animation starts, the image will be clipped to a rectangular region. This rectangular region changes over time as the animation proceeds. The result can be seen on the right.

### Creating Evaluators

Sometimes the evaluators supplied by the standard Android API are not enough. In this case you can simply define your own. All you need to do is implement the TypeEvaluator<T> interface. This is a generic interface. The type parameter T should be the type of the property that you want to animate. The TypeEvaluator<T> interface consists of a single method that needs to be implemented.

public T evaluate(float fraction, T startValue, T endValue);

The idea is that the method is given a start value and an end value and should return an interpolated value. The float fraction determines the position at which to interpolate. When fraction is 0.0 then evaluate should return the start value. When fraction is 1.0 then it should return the end value. For any number between 0.0 and 1.0 is should return an object that lies somewhere between the start value and the end value.

#### A MatrixEvaluator

Let’s look at an example. ImageView has a method called setImageMatrix. This method allows you to specify a transformation matrix that will be applied to the image before it is drawn. Transformation matrices can be used to specify rotations and scaling of the image but you can also specify a skew. The rotation and scale can also be set using setRotation or setScale. The skew, on the other hand, can’t be directly applied in any way  other than using matrix transformations. This means that, in order to animate the skew of an image we need to create an evaluator that operates on Matrix objects.

public class MatrixEvaluator implements TypeEvaluator<Matrix> {
public Matrix evaluate(float fraction,
Matrix startValue,
Matrix endValue) {
float[] startEntries = new float[9];
float[] endEntries = new float[9];
float[] currentEntries = new float[9];

startValue.getValues(startEntries);
endValue.getValues(endEntries);

for (int i=0; i<9; i++)
currentEntries[i] = (1-fraction)*startEntries[i]
+ fraction*endEntries[i];

Matrix matrix = new Matrix();
matrix.setValues(currentEntries);
return matrix;
}
}

The MatrixEvaluator class implements the TypeEvaluator with the type parameter set to Matrix. This means that we have to implement the evaluate method with T replaced by Matrix. In the first three lines we create float arrays that will hold the matrix elements for the start value, the end value and the interpolated value. Next we fill the arrays startEntries and endEntries from their corresponding matrix by calling getValues.

The loop iterates over all 9 matrix elements and simply interpolates between the start and end values using fraction. Finally we create a new Matrix object called matrix which we fill with the values and return it.

Using the new evaluator is relatively straightforward. Most of the work will in be creating the matrices needed to set the start and end values for the animation.

ImageView image = (ImageView)findViewById(R.id.some_image);
image.setScaleType(ScaleType.MATRIX);

float scale =
(float)image.getHeight()
/(float)image.getDrawable().getIntrinsicHeight();
Matrix from = new Matrix();
from.setScale(scale, scale);
from.postSkew(-0.5f, 0.0f);
Matrix to = new Matrix(image.getMatrix());
to.setScale(scale, scale);
to.postSkew(0.5f, 0.0f);

We first get the ImageView from the layout. ImageView has a number of different scaling types. We need to set the scaling type to ScaleType.MATRIX so that the image will be scaled using a transformation matrix. We could have also done this in the XML layout file using the android:scaleType attribute. A scale is calculated so that the image will fit inside the view using the height of the View and the intrinsic height of the Drawable. Now we have everything to create two matrices, set their scale values and skew values.

Creating the animation object is, again, just a single line.

ObjectAnimator anim = ObjectAnimator.ofObject(image,
"imageMatrix",
new MatrixEvaluator(),
from, to);

The imageMatrix property corresponds to the setImageMatrix method. We pass a new MatrixEvaluator as third argument and the two matrices from and to. Now all we have to do is start the animation.

anim.setDuration(500);
anim.setRepeatCount(5);
anim.setRepeatMode(ObjectAnimator.REVERSE);
anim.start();

An animation using the MatrixEvaluator

For a little extra effect, we repeat the animation 5 times and set the repeat mode to ObjectAnimator.REVERSE. This means that the animation will be played forward and backward 5 times. The resulting animation can be seen on the right.

#### A Colour Evaluator Using HSV Colour Model

We have used the RGBEvaluator in an example above. This evaluator is part of the Android SDK. Sometimes the resulting animation is not quite satisfactory. Maybe you would like to cycle through the colours using the HSV colour model. This means that an animation from red to blue will animate through the rainbow colours and include yellow and green colours on the way. Here we will create such an HsvEvaluator.

public class HsvEvaluator implements TypeEvaluator<Integer> {
public Integer evaluate(float fraction,
Integer startValue,
Integer endValue) {
float[] startHsv = new float[3];
float[] endHsv = new float[3];
float[] currentHsv = new float[3];

Color.colorToHSV(startValue, startHsv);
Color.colorToHSV(endValue, endHsv);

for (int i=0; i<3; i++)
currentHsv[i] = (1-fraction)*startHsv[i] + fraction*endHsv[i];

while (currentHsv[0]>=360.0f) currentHsv[0] -= 360.0f;
while (currentHsv[0]<0.0f) currentHsv[0] += 360.0f;

return Color.HSVToColor(currentHsv);
}
}

The code follows pretty much the same pattern as the MatrixEvaluator. Colours in Android are represented by 32 bit integers. This means that the HsvEvaluator should implement TypeEvaluator<Integer>. The corresponding evaluate method first converts the colours to the HSV colour model. The HSV values are stores in float arrays of length 3 corresponding to hue, saturation and value. The static method Color.colorToHsv fills the arrays for the start and end colours. The loop then interpolates the colours between the start and end values.

There is one pitfall however. The reverse transformation, from HSV back to int will clip the values if they are out of bounds. This might seem reasonable but the hue value is cyclic. This means that values above 360.0 should be mapped back into the interval from 0.0 to 360.0. In the same way a value below 0.0 should also be mapped into the interval. We can simply do this by adding or subtracting 360.0 from the number until it lies inside the interval.

You might ask how one could ever obtain values that lie outside the interval, when the start and end values will definitely be inside the interval. After all, we are interpolating between the two limiting values. Well, not quite. Remember our discussion of interpolators? The AnticipateInterpolator will produce output values below 0.0 and the OvershootInterpolator will produce values above 1.0. This means that we have to account for the case that fraction lies outside the interval from 0.0 to 1.0.

After this discussion, we can finally start our colour animation.

View square = findViewById(R.id.some_view);

ObjectAnimator anim = ObjectAnimator.ofObject(square,
"backgroundColor",
new HsvEvaluator(),
Color.RED, Color.BLUE);
anim.setDuration(2000);
anim.start();

An animation using the HsvEvaluator

The result of this animation can be seen on the right. Note the difference between this colour animation and the previous one which was using the RGBEvaluator.

I hope you enjoyed this weeks tutorial. As always, the code can be found on Github.

1. Anonymous

Very interesting and helpful article. Thanks!

2. vikas kumar jha

it is very nice tutorial,
how to reset the position and size of view after animation.
ie i want implementation like fillAfter() of animation class with object animator.

1. Mikail (Post author)

If you want to influence the appearance of the view after the animation has finished you can implement an AnimatorListener and set the view’s properties in the onAnimationEnd method.

1. vikas kumar jha

Thank you so much mikail. this helps me. solved my problem

3. vikas kumar jha

I have one custom RelativeLayout,where i used canvas.clipRect(rect) method. and then in some other part of my program i want to animate clipbouds property using objectAnimator and RectEvaluator. But it is not working.
just for testing purpose,if i comment my canvas.clipRect(rect),then clipbound animation work fine, please give me the solution. below is some my code.

canvas.clipRect(new Rect(left, top, right, bottom), Region.Op.REPLACE); in custom Relativelayout.

for animation

Rect localRect = new Rect();
shape.getLocalVisibleRect(localRect);
rectFrom.right = rectFrom.left;
rectFrom.bottom = rectFrom.height();
Rect rectFrom = new Rect(localRect),rectTo = new Rect(localRect);
ObjectAnimator.ofObject(shape, “clipBounds”, new RectEvaluator(), rectFrom, rectTo);
** Shape is my custome RelativeLayout.

4. A Short History of C. elegans Research | WormClassroom


text:
# Solve congruence: $45x \equiv 15 \pmod{78}$ (What am I doing wrong?)

Question about solving congruence. I've worked out how to solve them for the most part except for the following problem I'm having: $$45x \equiv 15 \pmod{78}$$ By the euclidean algorithm, I work out that the gcd of 45 and 78 = 3 which means there exists 3 solutions.

I divide through the congruence by the gcd, 3, to get a new congruence: $$15x \equiv 3 \pmod{26}$$

The gcd of this is 1, which means there exists 1 unique solution. By extended euclidean algorithm I work out that the solution is $21 \pmod{26}$

But now I'm asked to find the solution in terms of the original modulus, mod 78.

In my understanding to do this all you need to do is take the solution of the new congruence, which is 21, and keep adding 26 two more times to get 3 different solutions (which works for other problems I've done), which gets me solutions: 21, 47 and 73 (mod 78) but this is incorrect.

The correct solutions are 9, 35, 61.

What am I doing wrong?

When you divide through by 3, the resulting congruence should be $$15x\equiv 5\pmod{26},$$ not $$15x\equiv 3\pmod{26}.$$
$$15/3=5.$$