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    Review on structural resistance to downburst wind loads
    TIAN Li,Wenzhe BI,Sarim Saleem SIDDIQUI,Kaiyue LIU
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 32-41.   DOI: 10.6040/j.issn.1672-3961.0.2020.102
    Abstract700)   HTML27)    PDF(pc) (2558KB)(51)       Save

    Researches of downburst in the field of structural wind resistance were introduced. Concerning all kinds of building structures related to people's production and life, this paper reviewed the research and the existing problems to date on the structural resistance to downburst from five aspects: the field measurements, the analytical models, the numerical simulation of the downburst, the wind-tunnel test for downburst, and the wind-induced response analysis of structures. Some problems in view of the structural resistance to downburst for further study were proposed.

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    Review on development of simultaneous localization and mapping technology
    Jianqing WU,Xiuguang SONG
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 16-31.   DOI: 10.6040/j.issn.1672-3961.0.2021.168
    Abstract524)   HTML230)    PDF(pc) (2986KB)(267)       Save

    As a hot spot in the field of intelligent transportation, simultaneous localization and mapping (SLAM) technology is the key to autonomous path planning for self-driving vehicles. This review focused on four parts with introduction of sensors related to SLAM technology, localization, mapping, and multi-sensor integration. Each step of realization for SLAM technology was introduced from advantages and disadvantages, range of application, probability algorithm, types of map, and integration methods. Based on the investigation of relevant researches about multi-sensor integration, common problems of SLAM technology were analyzed, future development trend and practical engineering application of SLAM technology were prospected.

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    Research progress of ocean wave energy converters
    Yanjun LIU,Shuang WU,Dengshuai WANG,Ruohong WANG
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 63-75.   DOI: 10.6040/j.issn.1672-3961.0.2021.234
    Abstract443)   HTML39)    PDF(pc) (13090KB)(267)       Save

    In order to accurately keeping the developments of ocean wave energy utilization technology, the important research progress of wave energy converters was reviewed. The forms of wave energy converters had not yet converged. According to the classification principle of different energy capture methods, the working principle and the energy conversion system of three main types of devices, namely, oscillating water column, overtopping and oscillating bodies were introduced. The advantages and disadvantages of each type of converter were analyzed. Typical engineering devices were selected for detailed introduction. The engineering devices which had been completed sea trial in China were summarized. It has been found that the oscillation type was the most popular type of converter in China. The research progress related to the performance evaluation of wave energy converters were summarized, but there was no unified evaluation standard yet. The difficulties and the main breakthrough directions of the developments of wave energy converters were discussed from three aspects of high efficiency and stability, reliability and cost, and the construction of diversified integrated platforms.

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    Automatic detection research of arrhythmia based on CNN-LSTM hybrid model
    TAO Liang, LIU Baoning, LIANG Wei
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 30-36.   DOI: 10.6040/j.issn.1672-3961.0.2020.445
    Abstract433)      PDF(pc) (3912KB)(206)       Save
    A hybrid algorithm of convolutional neural network and long short-term memory network was proposed for automatic detection of arrhythmias. The model structure was composed of 5 convolutional layers, 5 pooled layers, 1 LSTM layer and 1 fully connected layer. By taking advantage of CNN's ability to automatically extract features and LSTM's ability to capture dependencies before and after time series, the simple preprocessed ECG signal data were directly input into the hybrid model. The whole model combined the two steps of feature extraction and classifier classification, so as to identify five different arrhythmias more efficiently and accurately. The accuracy, sensitivity and specificity of the test set were 99.48%, 99.47% and 99.86% respectively. The experimental results showed that the proposed method could efficiently and accurately identify different types of arrhythmias.
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    Review and prospect of renewable energy ramp events
    Xueshan HAN,Xinyi WANG,Ming YANG,Yixiao YU
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 53-62.   DOI: 10.6040/j.issn.1672-3961.0.2020.287
    Abstract420)   HTML28)    PDF(pc) (2283KB)(87)       Save

    This article elaborated the wind and solar power ramp events from the three levels: the definition, prediction method and control strategy. The common definitions of wind and solar ramp were listed, and their advantages and disadvantages were analyzed in turn. It summarized the current mainstream prediction methods of ramp events, which were divided into direct method and indirect method according to whether the power prediction results were used, and the commonly used evaluation indicators were evaluated. It elaborated the current commonly used methods of control strategy, taking energy storage participation as a division, it was divided into finite control strategy without energy storage participation and infinite control strategy with energy storage participation. The current research problems and key research directions in the future were summarized and prospected.

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    Evacuation simulation model based on multi-target driven artificial bee colony algorithm
    Xinlu ZONG,Jiayuan DU
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 1-6.   DOI: 10.6040/j.issn.1672-3961.0.2020.259
    Abstract399)   HTML532)    PDF(pc) (4584KB)(126)       Save

    An evacuation simulation model based on multi-target driven artificial bee colony algorithm was presented. Based on the artificial bee colony algorithm, the visual field was used for each following bee to choose the individual with the best fitness value in the field as its visual leading bee and avoid blind choice. A multi-target driven artificial bee colony algorithm was proposed. The moving direction of each following bee was affected by multiple targets, including inertial leading bee, global optimal bee, historical optimal bee and visual leading bee. The experimental results showed that the multi-target driven artificial bee colony algorithm had higher efficiency and achieved better performance and more reasonable distribution in the case of larger number of evacuees. The model and algorithm presented could effectively improve evacuation efficiency and was suitable for the evacuation problem in multi-obstacle situation.

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    Optimal calculation method of pavement shakedown limit based on genetic algorithm
    Xiuguang SONG,Yingchao ZHANG,Peizhi ZHUANG,He YANG,Haifeng ZHANG,Juan WANG
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 1-7.   DOI: 10.6040/j.issn.1672-3961.0.2021.153
    Abstract393)   HTML291)    PDF(pc) (4005KB)(182)       Save

    To solve the problem that road structures are prone to elasto-plastic deformation under the action of long-term reciprocating vehicle loads, based on the static shakedown theorem, the shakedown behavior of the semi-infinite space Mohr-Coulomb structure under the Hertz load was studied, and the genetic algorithm was introduced to construct an efficient calculation method for the lower limit of the shakedown limit of the road structure under the reciprocating vehicle load. The accuracy and efficiency of the new method was verified by comparison with the existing solution method and parameter analysis.

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    Algorithm of adaptive slope adjustment of quadruped robot based on model predictive control and its application
    LIANG Qixing, LI Bin, LI Zhi, ZHANG Hui, RONG Xuewen, FAN Yong
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 37-44.   DOI: 10.6040/j.issn.1672-3961.0.2020.320
    Abstract370)      PDF(pc) (6868KB)(222)       Save
    In order to realize the adaptive and stable walking of the quadruped robot on slope terrain, the adaptive adjustment strategies of both feet position and trunk posture of quadruped robot on slope were proposed based on the model predictive control. The posture determination parameters of the robot in locomotion were measured by the inertial measurement unit(IMU). By means of the derived foot end trajectory algorithm, the coordinate mapping of its toe position was obtained in order to adjust the center of gravity of the robot on the slope. Then the adaptive adjustment of the trunk posture of the robot in the process of climbing could be achieved through the trunk posture adjustment algorithm by means of designed “virtual slope”. With the help of the physical platform of quadruped robot and the actual slope terrain environment built in the laboratory, the feasibility and validity of the proposed algorithm are verified. Experimental result showed that the proposed slope adaptive control method had improved the stability margin of the robot on the slope and optimized the foot end motion space, thus leading to the realization of adaptive adjustment in climbing slope for the quadruped robot.
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    Prediction method of power grid emergency supplies under meteorological disasters
    Qingfa CHAI,Shoujing SUN,Jifu QIU,Ming CHEN,Zhen WEI,Wei CONG
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 76-83.   DOI: 10.6040/j.issn.1672-3961.0.2020.527
    Abstract357)   HTML138)    PDF(pc) (2767KB)(58)       Save

    In order to improve the efficiency of grid emergency repairs, a method for predicting emergency supplies under the conditions of power grid meteorological disasters combining case-based reasoning, deep belief network and deep learning was proposed. Based on meteorological data, power grid maintenance data and geographic environment data, this method was used case-based reasoning to determine the appropriate input and output structure of the prediction model, and different methods was used to process and quantify according to the characteristics of disagreeing input factors. Deep belief networks were used to complete case adaptation, and integrate accident scale information was used to establish a dynamic power grid emergency supplies prediction model. The analysis results showed that the emergency material prediction method proposed in this paper could comprehensively analyze various characteristic factors, and combined the scale of the accident to establish the relationship between the emergency material demand of the power grid, and accurately predicted the material demand for the emergency response of the power grid under the weather disaster. and provided a scientific reference for emergency decision-making of power grids.

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    Comprehensive protection scheme for grounding fault in low resistance grounding system
    HUANG Fuquan, WANG Tinghuang, ZHANG Haitai, LIU Zijun, LI Guodong
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 113-118.   DOI: 10.6040/j.issn.1672-3961.0.2020.159
    Abstract341)      PDF(pc) (2199KB)(100)       Save
    Because the existing grounding protection in low resistance grounding system had imcomplete protection configuration, poor selectivity, low sensitivity and insufficient ability to detect high-imedance grounding fault, the characteristics of zero sequence current while single-phase grounding fault occured in low resistance grounding system was analyzied. With the help of longitudinal cooperation between the upper and lower protections, the multistage grounding protection based on zero sequence current and the high sensitivity grounding protection based on low setting and time delay were proposed, and also the grounding protection configuration scheme and the setting principles at all levels were discussed. Fault line selection method was proposed for the high-impedance grounding fault using the lateral comparasion of the amplitudes of zero sequence currents between the outlet of each feeder and the neutral line. The feasibility and reliability of the proposed comprehensive protection scheme for grounding fault were verified by the simulation in a typical small resistance grounding distribution network.
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    Forward modeling analysis of seismic wave field for TGS360pro advanced prediction of groundwater: taking the karst model as an example
    ZHANG Mingcai, JU Guanghong, XIONG Zhangqiang, ZHANG Dazhou
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 68-75.   DOI: 10.6040/j.issn.1672-3961.0.2020.158
    Abstract341)      PDF(pc) (8916KB)(119)       Save
    In order to avoid the occurrence of water gushing accident due to the inaccurate detection of the underground water storage state in front of the tunnel during the excavation of the tunnel, the tunnel geology survey TGS360pro System was used to accurately and efficiently detect the water-bearing body in front of the tunnel face by using the relation between the instantaneous amplitude and frequency of seismic wave signal and the rock structure plane, at the same time, based on the principle of TGS360pro tunnel Prediction System, the geological model with water-filled cave in front of the face was simulated by using spectral element method, through the stress curve, the numerical analysis results showed that the TGS360pro Tunnel Prediction System could effectively detect the water-rich condition in front of the tunnel, it had the prospect of popularization and application in tunnel excavation construction.
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    Optimization of ventilation system of TBM tunnel construction and evaluation of dust suppression effect
    WANG Chunguo
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 52-60.   DOI: 10.6040/j.issn.1672-3961.0.2020.468
    Abstract340)      PDF(pc) (5863KB)(126)       Save
    Hard rock tunneling boring machine(TBM)produces a large amount of dust during construction, which is an important factor affecting the operating environment and the health of workers. To further optimize the construction ventilation and dust removal effect, combined with the actual working conditions of Qingdao Metro Line 1 double shield TBM, Ansys-Fluent software was used to carry out numerical analysis of the tunnel excavation process. The wind speed and dust mass concentration at each location of the tunnel were detected and compared with the numerical simulation results to verify the effectiveness of the model. In view of whether it is necessary to open the dust removal system in the process of TBM tunnel construction, as well as the location of dust removal tuyere and the selection of optimal suction flow, numerical simulation was carried out. When the dust removal system was turned off or the dust removal system was turned on but the suction flow was below 4 m3/s, and the dust diffuses to most areas of the TBM tunneling area. When the dust duct was 15 m away from the hand surface and the suction airflow was 12 m3/s, the dust removal effect reached the best, and the dust diffusion distance was reduced to 45 m, which could effectively remove dust. The research results could provide a scientific basis for the design and construction of tunnel ventilation and dust removal.
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    Review and prospect of the development of heat exchanger structure
    Wenjing DU,Junzhe ZHAO,Lixin ZHANG,Zhan WANG,Wanxiang JI
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 76-83.   DOI: 10.6040/j.issn.1672-3961.0.2020.423
    Abstract339)   HTML29)    PDF(pc) (4892KB)(115)       Save

    The development of heat exchanger for more than 200 years was introduced. The generation and typical applications of heat exchangers with different structures were reviewed. Four heat exchangers with different structures including shell-and-tube heat exchanger, plate heat exchanger, microstructure heat exchanger, and printed circuit heat exchanger were described emphatically, and the development work of related geometric parameter optimization and structure improvement was carried out to realize heat transfer enhancement. The existing problems and limitations in the structure design of the heat exchanger were analyzed, and the specific suggestions and development trends for the structure improvement of the heat exchanger in the future were proposed.

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    Adaptive multi-domain sentiment analysis based on knowledge distillation
    YANG Xiuyuan, PENG Tao, YANG Liang, LIN Hongfei
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 15-21.   DOI: 10.6040/j.issn.1672-3961.0.2020.249
    Abstract333)      PDF(pc) (2317KB)(138)       Save
    An adaptive multi-domain knowledge distillation framework was proposed, which effectively accelerated reasoning and reduced model parameters while ensuring model performance. The knowledge distillation method was used to study sentiment analysis problems. When performing knowledge distillation for each specific field, model distillation involved word embedding layer distillation, coding layer distillation(attention distillation, hidden state distillation), output prediction layer distillation and other aspects of distillation, in order to learn all aspects knowledge from the specific field teacher model. Selectively learning the importance of the teacher model corresponding to different fields to the data was proposed, which further improved the accuracy of the prediction results. The experimental results on multiple public datasets showed that after single-domain knowledge distillation increased the model accuracy by an average of 2.39%, while multi-domain knowledge distillation increased the model accuracy by an average of 0.5%. Compared with the knowledge distillation of a single domain, this framework enhanced the generalization ability of the student model and improved the performance.
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    Median calculation algorithms based on GPU in OLAP
    WU Zhenpeng, ZHANG Jian, FAN Xingqi, LI Cuiping
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 7-14.   DOI: 10.6040/j.issn.1672-3961.0.2019.508
    Abstract332)      PDF(pc) (3119KB)(106)       Save
    An algorithm for one of the holistic aggregate operations in online analytical processing(OLAP)called Median was proposed based on graphics processing unit(GPU), which was named GPU-Median algorithm. This algorithm obtained the median of a series of data by segmenting the data, sorting the data by segments,cutting the data preceding the global median, and finally merging the uncut data. Through the algorithm above much time spent on global sorting was saved. Then an algorithm called GPU-Median+was presented in order to optimize and extend the GPU-Median algorithm. This algorithm implemented the aggregate operations through the collaboration of CPU and GPU, which used GPU to deal with segments of data and CPU to deal with global data. Experiments and analysis proved that the GPU-Median + algorithm reduced the time complexity of the median calculation from O(n2)to O(n)compared to the CPU algorithm,and that the GPU-Median + algorithm reduced a third of the calculation time compared to the radix sort algorithm on the GPU. The application of this algorithm enabled the GPU to improve its ability of parallel calculations when calculating the holistic aggregate function in OLAP, thus providing a new idea for improving the query performance of OLAP.
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    Small sample person re-identification combining Gabor features and convolution features
    FU Guixia, ZOU Guofeng, MAO Shuai, PAN Jinfeng, YIN Liju
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 22-29.   DOI: 10.6040/j.issn.1672-3961.0.2020.232
    Abstract326)      PDF(pc) (6150KB)(113)       Save
    In the video surveillance, the limited available person images and unreliable data annotation led to the performance degradation of supervised person re-identification. To solve these problems, we proposed an unsupervised small sample person re-identification method that integrated Gabor features and convolution features. Gabor transform was used to extract multi-scale and multi-direction person texture and edge information, so as to realize the data augmentation of small sample person images in feature level. The redundant information was eliminated by feature encoding to improve the efficiency of feature similarity calculation. The convolutional auto-encoder network was adopted to extract the nonlinear deep convolution feature of pedestrian, which avoided the dependence of supervised learning algorithm on data annotation. The fusion of two heterogeneous features was applied to person similarity comparison, which implemented the feature augmentation of small samples and the improvement of person feature discrimination ability. Experiments were implemented based on Market-1501 and DukeMTMC-reID datasets, the rank-1 accuracy reached 74% and 67.1% respectively. The experimental results showed that the proposed network framework effectively improved the performance of small sample person re-identification.
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    Study on full face hard rock tunnel boring machine through the overpass in composite stratum
    Chunguo WANG
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 45-51.   DOI: 10.6040/j.issn.1672-3961.0.2020.525
    Abstract308)   HTML169)    PDF(pc) (8639KB)(83)       Save

    By using the numerical calculation method, the double tunnel underpass overpass was established according to the actual engineering situation, the strain law of the tunnel underpass municipal bridge was comprehensively analyzed, the multi-point displacement of the bridge was monitored, and the weak point reinforcement measures of the tunnel orthogonal underpass bridge were proposed. The results showed that the influence of the two-way simultaneous excavation of the right tunnel was almost the same as that of the two-way simultaneous excavation of the right tunnel. The left tunnel was excavated first and then the right tunnel was excavated. The uplift part of the bridge deck would gradually subside with the excavation of the right tunnel. It could be seen that the left tunnel excavation first and then the right tunnel excavation had the largest impact on the bridge deck, which was easy to cause the uneven settlement of the bridge. The uneven settlement of bridge deck caused by tunnel excavation could temporarily support and reinforce the piers, and the circumferential soil around the piers could be replaced with concrete to reduce the settlement of the piers and bridge deck.

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    Location optimization of median BRT station at intersection
    GUO Rongrong, ZHANG Ruhua, MA Xinhui, GUO Senyao
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 61-67.   DOI: 10.6040/j.issn.1672-3961.0.2020.345
    Abstract298)      PDF(pc) (1618KB)(72)       Save
    Based on the optimal comprehensive time efficiency of BRT vehicles and arriving passengers, a station selection optimization method was proposed. The time efficiency model was established and calculated by fuzzy analytic hierarchy process and genetic algorithm. Huanggang Road Station in Jinan was selected for case analysis. The results showed that the larger the weight of BRT operation time in a measurement unit was, the smaller the weight of arrival passenger travel time was, and the greater the buffer distance when the time efficiency was optimal. When the case station was set up at 25 meters downstream of the intersection, the efficiency of comprehensive time was the most optimal, which was 20% higher than the current situation.
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    Modified calculation method of shaft friction for driven pile considering particle size effect
    Peizhi ZHUANG,Yingchao ZHANG,Xiuguang SONG,He YANG,Zhicheng GUO,Yan HU
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 8-15.   DOI: 10.6040/j.issn.1672-3961.0.2021.161
    Abstract297)   HTML223)    PDF(pc) (7930KB)(124)       Save

    This study aimed to investigate the influence of particle size on the micropile by conducting theoretical analysis and model tests. The empirical relationship between the critical friction angle and the relative roughness at the pile-soil interface was established, and thus the critical friction angle could be determined quantitively in consideration of the particle size of sands. To emphasis the influence of particle size on the additional normal stress at the soil-pile interface, the shear band at the soil-pile interface was modelled as a hollow cylinder and then a new modified method was proposed based on the elastic cavity expansion theory. Only two new parameters, Poisson's ratio and the thickness of the shear band, were involved in the modified method, which was validated by comparison with model tests. It was found that the pile shaft friction was mainly determined by the pile roughness and the ratio of pile diameter to sand median size and the critical state angle at the pile-soil interface, while the additional normal stress mainly results from the pile roughness and the ratio of pile diameter to sand median size, respectively. The research could provide the valueable reference for the bearing capacity design of micropiles.

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    Short-term load forecasting of iron and steel industry area based on combination model of SVM and LSTM
    Xiaoyan QI,Hengjie LIU,Qiuhua HOU,Xiaoyu LIU,Yanchao TAN,Liancheng WANG
    Journal of Shandong University(Engineering Science)    2021, 51 (4): 91-98.   DOI: 10.6040/j.issn.1672-3961.0.2020.539
    Abstract297)   HTML95)    PDF(pc) (5138KB)(47)       Save

    A short-term load forecasting algorithm combining long short-term memory (LSTM) and support vector machine (SVM) was proposed to solve the low accuracy problem of short-term load forecasting due to the large-scale iron and steel enterprise power consumption impact on regional load. The research thoroughly analyzed the load characteristics of the selected region with predominant iron and steel mill load, which divided the load into the impulse load and others based on its various components.Covariance algorithm and Pearson algorithm were used to analyze the correlation and differentiation of load influence factors. Six attributes of historical load, temperature, date type, steel price, electricity price and iron ore price were selected as load forecasting. The fuzzy weight assignment was used to fuse LSTM and SVM which got the final load forecasting result. The simulation results showed that the proposed method could predict the short-term load more accurately than the single LSTM or SVM.

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    Pollution characteristics and intake risk assessment of short and medium-chain chlorinated paraffins in foods in Jinan
    Xinxin FANG,Shiwen ZHANG,Yuting ZHU,Wei JIANG,Zhaoyuan ZHANG,Nan ZHAO
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 119-128.   DOI: 10.6040/j.issn.1672-3961.0.2021.001
    Abstract290)   HTML182)    PDF(pc) (3853KB)(155)       Save

    To explore the distribution status and intake risk of short-chain chlorinated paraffins (C10-13, SCCPs) and medium-chain chlorinated paraffins (C14-17, MCCPs) in food in Jinan city, 82 kinds of food were collected in Jinan in 2020 and analyzed by chlorine enhanced atmospheric pressure chemical ionization source- four-stage pole time-of-flight mass spectrometry. The results showed that the concentration of wet weight of SCCPs in food samples ranged from 5.3 to 2 483.2 ng/g, MCCPs ranged from 4.6 to 605.1 ng/g. The concentration of wet weight of SCCPs in Peanut oil was the highest, which was 2 115.5 ng/g. The concentration of wet weight of SCCPs in balsam pear was the lowest, which was 5.7 ng/g. The concentration of wet weight of MCCPs in soybean oil was the highest, which was 605.5 ng/g. The concentration of wet weight of MCCPs in Chinese cabbage was the lowest, which was 6.2 ng/g. The estimated daily intake (EDI) of SCCPs was the highest in staple foods, which was 2 619.2 ng/(kg ·d) and the lowest in aquatic foods, which was 17.7 ng/(kg ·d). The EDI of MCCPs was the highest in staple foods, which was 2 117.6 ng/(kg ·d), and the lowest in aquatic foods, which was 12.1 ng/(kg ·d). The hazard quotients (HQ) of SCCPs、MCCPs was 0.041 and 0.032, respectively. The purpose of this study was to provide reference data for the assessment of the risk of exposure to CPs among the population in Jinan.

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    Wind induce vibration control of chimney with suspended flue
    LI Xu, LIU Bing, CHEN Ying, WANG Peijun
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 101-112.   DOI: 10.6040/j.issn.1672-3961.0.2020.281
    Abstract288)      PDF(pc) (4454KB)(82)       Save
    The wind induced vibration control of a high rise reinforced concrete chimney with suspended flues(CSMF)was conducted by using rotational friction dampers(RFD). The detailing of a RFD restraint joint was presented. The wind induced vibration control effect was firstly investigated, and the state space formulation of the equation of motion of CSMF was derived based on Lagrange's equations. A CSMF of 175 m high was then taken an example to investigate the feasibility of the proposed control strategy. Five vibration control schemes were compared and the results showed that the vibration of CSMF could be substantially suppressed by using RFD with optimal parameters, position and suspended flue length. FRD was superior to TMD due to its small auxiliary mass and little space occupation.
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    Reduced-order analytical model to evaluate photovoltaic low-voltage ride-through performance
    NIU Shuanbao, HUO Chao, CHEN Chunmeng, KE Xianbo, WANG Xiaohui, ZHANG Qiang, CHEN Ning
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 91-100.   DOI: 10.6040/j.issn.1672-3961.0.2020.472
    Abstract285)      PDF(pc) (3951KB)(90)       Save
    A reduced-order analytical model to evaluate the performance of PV in case of low-voltage ride through(LVRT)was proposed based on the idea of order reduction at each unit, focusing on the DC bus voltage which determined the outcome of ride-through. Such a method covered the major factors with regard to PV LVRT, and included the responses by the converter controller and phase-locked loop. Meanwhile, it took the supporting of reactive power outputs from PV on the point of common coupling(PCC)voltage into consideration, so as to reflect that PV provides reactive power support to AC system. To validate the proposed reduced-order analytical model, the comparison with the simulation results derived from PSCAD confirmed its accuracy and feasibility.
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    Analysis of the influence of the underside baffle and deflector of the fume hood on the flow field
    Ruiyi YAN,Zhen DONG,Sen LU,Yanhua LAI,Mingxin LÜ
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 122-130.   DOI: 10.6040/j.issn.1672-3961.0.2021.177
    Abstract285)   HTML23)    PDF(pc) (19825KB)(247)       Save

    For the phenomenon of vortex and gas escape in the flow field of the extant fume hood, the computational fluid dynamics method was used for simulation. This research changed the shape parameters of the underside structure of the fume hood window, used circular arc baffles with different radii, elliptical arc baffles with different lengths, and added deflectors with different radii. Then this research studied the influence of structural changes on the flow field in the fume hood by analyzing the size and location of the vortex to obtain the direction of structural optimization. The results showed that when the height of the underside baffle was low and the length was short, there was obvious large vortex in the center position of the fume hood and near the wall. A baffle with a height greater than 50 mm and a length greater than 90 mm could significantly reduce the vortex at the center of the fume hood and at the junction of the baffle and the side wall. Adding a deflector could optimize the flow field and make the center vortex disappear, and the radius of the deflector should not be greater than 70 mm, otherwise obvious vortices would be excited on the outside and end of the baffle, which provides a basis for the rational design of fume hoods.

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    Review of frequency dynamic behavior evolution and analysis method requirements of power system
    Hengxu ZHANG,Yongji CAO,Yi ZHANG,Changgang LI,Jiacheng RUAN,VLADIMIR Terzija
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 42-52.   DOI: 10.6040/j.issn.1672-3961.0.2021.174
    Abstract281)   HTML24)    PDF(pc) (1810KB)(64)       Save

    The development of renewable energies changed the operation states of power systems, which complicated the frequency dynamics and brought about new challenges to frequency security and stability. The process of frequency dynamic response was introduced, whose quantitative characteristics and analysis methods were reviewed. And the strengths and promising prospects of frequency dynamics analysis method based on artificial intelligence were emphasized. From the viewpoints of the strong variability of renewables energies, the low inertia of nonsynchronous power sources, and the high risk of large power deficits and cascading faults, the changes of the operation states of power systems were analyzed, and the new requirements on frequency analysis and control were discussed. The inertia definition of power systems with the rapid development of renewable energies was revealed, and the virtual inertia control methods were reviewed. The strengths and promising prospects of the coordination control of multi-type virtual inertia were emphasized. The important issues to be focused in the research area of frequency analysis and control were summarized, and the suggestions for further studies were provided.

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    Image-dependent fusion method for saliency maps
    Ye LIANG,Nan MA,Hongzhe LIU
    Journal of Shandong University(Engineering Science)    2021, 51 (4): 1-7.   DOI: 10.6040/j.issn.1672-3961.0.2020.266
    Abstract275)   HTML29)    PDF(pc) (4939KB)(108)       Save

    A saliency fusion method based on ridge regression was proposed to obtain better detection performance. The nearest neighbor set of the image to be detected was searched in the training set. The ridge regression method was used to estimate the fusion coefficients of different saliency maps. The saliency maps of different detection methods were fused. This method fully considered the differences of detection methods, and solved the problem of saliency map fusion in the absence of benchmark binary annotations. The AUC value of the proposed method was 0.911 on ECSSD dataset. The AUC value of the proposed method was 0.987 on HKU-IS dataset. The AUC value of the proposed method was 0.953 on DUT-OMRON dataset. The efficiency of the proposed method was verified by experimental results.

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    Photovoltaic power prediction method based on NWP irradiance inclination conversion
    Wenling JIANG,Yanqing ZHAO,Bo WANG,Shuanglei FENG,Yan PEI,Fei ZHANG
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 114-121.   DOI: 10.6040/j.issn.1672-3961.0.2020.104
    Abstract271)   HTML23)    PDF(pc) (2582KB)(164)       Save

    Short-term photovoltaic (PV) power predictions statistical methods generally used the horizontal irradiance in numerical weather prediction (NWP) directly, but not the inclined irradiance received by tilt PV panels, which led to the calculation results not accurate enough. This paper proposed a new method to convert horizontal irradiance to inclined one. The method distinguished scattering into molecular scattering and Mie scattering with different properties, and then converted them separately. Using the new method, the paper converted NWP horizontal irradiance to inclined one. Based on inclined one, PV power model and prediction were made. The result of an example showed that the new method, whose root mean square error was 10.25% and correlation coefficient was 0.914 0, was more accurate than the traditional method, which used NWP horizontal irradiance directly.

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    Distribution law and calculation method of earth pressure in culvert under reinforced embankment
    Xiuguang SONG,Yimin ZHAO,Hongbo ZHANG,Zhenyu YANG,Qiang YANG
    Journal of Shandong University(Engineering Science)    2021, 51 (4): 43-53.   DOI: 10.6040/j.issn.1672-3961.0.2021.125
    Abstract256)   HTML14)    PDF(pc) (9207KB)(61)       Save

    Based on the scale model test, the difference settlement between the embankment and the culvert was simulated by changing the foundation compression modulus on both sides of the culvert to reveal the mechanism of reinforcement and subsidence reduction on the culvert roof, determine the distribution law of earth pressure on the culvert roof under the condition of embankment overloading, and deduce and establish the calculation formula of earth pressure.The results showed that the soil pressure at the top of the reinforced embankment was obviously higher than that of the ordinary embankment under the same foundation modulus. The embankment-culvert relative displacement decreased with the increase of the number of grid layers.Under the same reinforcement condition, the smaller the foundation compression modulus was, the higher the embankment-culvert relative displacement and the soil pressure on the culvert top would be.Combined with the soil arching effect and the mechanism of reinforcement and subsidence reduction, the calculation formula of earth pressure under the roof of reinforced embankment was established, and the reliability was verified with the model test results.

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    Method for safety management and control of tools and equipment used in substation based on ultra-wideband technology
    LI Ying, L(¨overU)Xuebin, LI Yan, SUN Shoujing
    Journal of Shandong University(Engineering Science)    2021, 51 (3): 84-90.   DOI: 10.6040/j.issn.1672-3961.0.2020.243
    Abstract237)      PDF(pc) (4805KB)(38)       Save
    A method for the safety management and control of construction tools based on ultra-wideband technology was propssed. The function ultra wide band technology information storage and high-precision positioning was used, through the link before, during, and after the use of tool management, to eliminate the blind area of tool information and safety management and control and prevent. Major hidden dangers to the safe operation of substations due to improper use of tools and improper disposal. In addition, through the on-site disposal of damaged tools, the management and control of tools was fundamentally improved.
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    Intelligent commutation system of distribution network based on differential evolution algorithm
    Yunlong ZHAO,Renfei CHE,Jiahui CHEN
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 107-113, 121.   DOI: 10.6040/j.issn.1672-3961.0.2020.110
    Abstract202)   HTML23)    PDF(pc) (1771KB)(53)       Save

    The application of three-phase intelligent commutation switch was an effective measure to solve the problem of three-phase load imbalance in low-voltage distribution network. Based on the commutation process of the three-phase intelligent commutation switch, an intelligent commutation system of the distribution network was proposed, which took the differential evolution algorithm as the core and the mixed solid-state switch as the foundation. Aiming at the unbalance degree of three-phase current and the action times of commutation switch, differential evolution algorithm was used to optimize the commutation strategy. The optimal commutation strategy was obtained through initialization, mutation, crossover and selection operation, which improved the real-time and accuracy of the system. In this paper, through the combination of magnetic holding relay and IGBT based solid-state switch, a fast switching method using hybrid solid-state switch was proposed, which the commutation switch showed the characteristics of low power consumption and strong current passing ability, and improved the reliability of the system. The feasibility of the algorithm and switch in fast switching and im-proving the power quality of the commutation process was verified by practical test.

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    Influence of calcite veins on shale anisotropy at the microscopic scale based on digital images
    Huailei SONG,Zhonghu WU,Liping LI,Yili LOU,Wenjibin SUN,Hao LIU,Yujun ZUO
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 91-99, 106.   DOI: 10.6040/j.issn.1672-3961.0.2020.276
    Abstract202)   HTML14)    PDF(pc) (10650KB)(42)       Save

    The Niutitang Formation shale cores were observed by micro-slice observations and core X-ray whole-rock mineral diffraction analysis, and 7 groups of direct tensile numerical tests under different azimuth angles were performed. The test results showed that the calcite veins had a significant effect on the anisotropy of shale tensile strength. When the azimuth angle increased, the tensile strength gradually decreased. The bedding effect coefficient of tensile strength showed a curve-like growth trend with the increase of azimuth angle, which reached the maximum when α=90°, which was 0.127. The failure modes of shale samples at different angles were very complicated, which could be roughly divided into the following three categories: tree root shape (0°, 15°), step shape (30°, 45°, 60°) and river shape (75°, 90°). Fractures preferentially extended along calcite veins, which might inhibit the formation of complex fracture networks in the shale matrix during hydraulic fracturing. There were also significant differences in the release of dissipated energy under the calcite veins at different angles. The release of dissipated energy under the calcite veins at different angles was also significantly different. When α=0°, 15°, 30°, and 45°, the AE energy was small in the early stage, and increased rapidly to the maximum when it approached the peak stress. When α=60°, 75°, 90°, the AE energy was small in the early stage, and began to increase in the middle stage, and it was the largest when it was close to the peak stress. The cumulative AE energy increased roughly exponentially with increasing strain, and the growth process consisted of three stages: flat period, accelerated period and skyrocketing period. The research results had important reference value for the initiation of hydraulic fractures in shale reservoirs, the prediction of expansion, and the enhancement of oil recovery.

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    Gas-liquid mixing in a dual grid-disc impeller stirred vessel
    Cuixun ZHANG,Mingjian CAO,Fengling YANG
    Journal of Shandong University(Engineering Science)    2021, 51 (4): 71-76, 83.   DOI: 10.6040/j.issn.1672-3961.0.2020.296
    Abstract201)   HTML4)    PDF(pc) (4232KB)(36)       Save

    In order to improve the gas-fluid mixing efficiency in the stirred vessel, by replacing the solid disc of standard Rushton impeller (RT) with a grid disc, the grid-disc Rushton impeller (RT-G) was designed. Grid independence test was completed. Gas holdup distributions of dual RT were numerically studied by the computational fluid dynamics (CFD) technique and compared with the literature data so as to validate the reliability of the numerical model and simulation method. The same numerical strategy was used to investigate the gas-liquid hydrodynamics of dual RT-G. Results were compared with those of dual RT and it was found that, under the operating condition studied here, dual RT-G had the same double-circulation flow field structure as RT. However, fluid axial velocity around the two RT-G impellers and axial pumping capacity could be enhanced, which contributed to improve the gas distribution state especially in regions adjacent to the impellers, between the upper and lower impeller, as well as in the top area of the stirred vessel. In terms of power consumption, the power number of dual RT-G before gassing was about 5% lower than that of dual RT, which indicated that RT-G was more energy-saving. The relative power demand (RPD) of dual RT-G after gassing was about 8% higher than dual RT, and accordingly was more efficient in gas dispersing.

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    Lightweight face super-resolution network based on asymmetric U-pyramid reconstruction
    Tongyu JIANG,Fan CHEN,Hongjie HE
    Journal of Shandong University(Engineering Science)    2022, 52 (1): 1-8, 18.   DOI: 10.6040/j.issn.1672-3961.0.2021.312
    Abstract198)   HTML8)    PDF(pc) (9804KB)(163)       Save

    A lightweight face super-resolution network was proposed in order to solve the problem that the model of deep convolutional neural network was complicated and difficult to be applied in the face super-resolution task. The coder composed of rescoding blocks was used for feature extraction, and pyramid reconstruction was introduced into the decoder to achieve fast and accurate super-resolution. To reduce the parameter number of the up-sampling operation in the decoding block, a non-uniform channel widening strategy based on resolution selection was adopted. To avoid adding extra branches, the prior knowledge of the face was introduced through heatmap loss. Experimental results showed that the model proposed in this paper could achieve light and accurate super-resolution reconstruction of ultra-low resolution face images that achieved better visual quality than the state-of-the-art method with lower model complexity.

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    Influence of concrete aggregate particle size on acoustic emission detection
    Junwei LI,Fei XU,Bing WANG,Yang GAO
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 84-90.   DOI: 10.6040/j.issn.1672-3961.0.2021.016
    Abstract192)   HTML17)    PDF(pc) (4738KB)(59)       Save

    The lead breaking test of concrete specimens with different aggregate sizes was carried out by using acoustic emission technology. The influences of different aggregate particle sizes on the positioning accuracy, sound velocity calibration and time parameter setting of acoustic emission detection concrete materials and the selection of the optimal sensor layout were investigated. The results showed that aggregate was one of the main factors affecting the accuracy of acoustic emission detection. When the aggregate particle size increased 5 mm, the sound velocity decreases by 7.5%. When the aggregate particle size increased 5 mm, the rise time decreased about 3.5%, and the maximum rise time is not more than 200 μs. Perform "multi-multi-point" tests could reasonably determine the optimal sensor arrangement and effectively reduce the positioning error, but it couldn't eliminate the error.

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    Horizontal bearing capacity of suction bucket foundation under wave dynamic load
    Haotian LUO,Ke WU,Yameng LI,Jiaxiang XU,Zhihao XING
    Journal of Shandong University(Engineering Science)    2021, 51 (5): 100-106.   DOI: 10.6040/j.issn.1672-3961.0.2020.443
    Abstract190)   HTML20)    PDF(pc) (4920KB)(26)       Save

    For the horizontal ultimate bearing capacity of the suction bucket foundation under horizontal dynamic loads such as waves and wind, the explicit dynamic method was adopted to establish the mechanical model of the suction bucket foundation under the wave dynamic load. Based on the infinite boundary and Rayleigh damping, the model optimization analysis was carried out, and the comparative study of the ultimate bearing performance of the foundation under static load and dynamic load (action time 0.5, 1, 2, 5 s) under the same horizontal displacement conditions was carried out. The research results showed that the horizontal ultimate bearing capacity curve of the bucket foundation under different dynamic load time decreased with the increase of the loading time compared with the static load, and gradually approached the static load bearing capacity curve. Affected by the damping of the rock and soil media on the seabed, the rotation center of the barrel under the horizontal load moved up to the top of the barrel as the time of the dynamic load decreased.

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    Cross social network user alignment via fusing node state information
    Jun HU,Dongmei YANG,Li LIU,Fujin ZHONG
    Journal of Shandong University(Engineering Science)    2021, 51 (6): 49-58.   DOI: 10.6040/j.issn.1672-3961.0.2021.281
    Abstract190)   HTML43)    PDF(pc) (3630KB)(37)       Save

    A cross social network user alignment method by fusing node state information was proposed. The local characteristics of nodes and node state information were captured through network representation to obtain the embedded vector of each account, and the aligned users were found by calculating the similarity between corresponding representations of different accounts. Experimental results on two real data sets showed that the proposed method could align more users than other methods. When predicting top-k of different scales, the proposed method could achieve an alignment precision of 50% at top-9 on the data set Twitter-Foursquare with dense network structure. Compared with other methods on the sparse and large network data set DM-ML, the improvement on alignment precision was 12.06%-36.62%. The analysis of F1-score also showed that the proposed method could effectively improve the performance of user alignment.

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    The analysis of key parameters of hydraulic energy storage system of wave energy converter
    Yingxin LIU,Jian QIN,Yanjun LIU
    Journal of Shandong University(Engineering Science)    2021, 51 (6): 1-8.   DOI: 10.6040/j.issn.1672-3961.0.2020.429
    Abstract189)   HTML25)    PDF(pc) (4298KB)(44)       Save

    To improve the efficiency of wave power generation technology, a mathematical model of the system from wave input to motor output was established. The key parameters that affected the system′s power generation capacity were analyzed by using theoretical modeling and simulating, so as to provide theoretical guidance for the research of the constant speed control strategy of the hydraulic energy conversion system. The hydraulic energy storage system of wave energy generation was composed of 3 parts. The mathematical model of the system was established by analyzing each component′s motion equation and energy equation, and finding the connection parameters between the two components. The key parameters and characteristics of the system were determined qualitatively by analyzing the system′s power equation. To confirm the accuracy of theoretical analysis, the AMEsim simulation platform was used to design and imitate the system. The results showed that the motor′s output power was affected by the height of the wave, period, flow area of the proportional flow valve and the motor displacement. The highest order of the influence was 1, 4, 4 and 2, respectively. The results also verified that the precharging pressure of the accumulator had little influence on the motor′s output power.

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    Fault diagnosis of vehicle-to-vehicle communication in networked traffic environment
    Haigen MIN,Yukun FANG,Xia WU,Wuqi WANG
    Journal of Shandong University(Engineering Science)    2021, 51 (6): 84-92.   DOI: 10.6040/j.issn.1672-3961.0.2021.353
    Abstract145)   HTML23)    PDF(pc) (7549KB)(30)       Save

    With vehicle platoon in intelligent transportation system as the background, this research established a vehicle platoon control model based on the intelligent driver model and analyzed the influence of delay in vehicle-to-vehicle communication on the stability of platoon control. A fault diagnosis method based on the update delay of vehicle-to-vehicle communication was proposed. The statistical characteristics of median and average were used to calculate the decision variables which were used to judge whether a fault had occurred. A two-layer sliding window was designed to smooth the decision variables and adaptively calculate the decision variable in real time. The Jarque-Bera algorithm was used to test the normality of the statistical distribution of the receiver's update delay within a period of time. If the distribution significantly deviated from the normal distribution, it was considered that the communication quality had deteriorated. Collecting vehicle speed data and vehicle-to-vehicle communication delay data at the testbed, simulations were conducted to analyze the statistical distribution characteristics of the vehicle-vehicle communication update delay in different scenarios and verify the influence on vehicle platoon control of vehicle-to-vehicle communication delay. The research results showed that the vehicle-to-vehicle communication delay caused drastic changes in the control rate during the collaborative control process. The communication fault diagnosis method based on the update delay could effectively diagnose whether the vehicle-to-vehicle communication quality had deteriorated.

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    Research progress of building structure under typhoon
    Li TIAN,Laiyi ZHANG,Yanming WANG,Juncai LIU
    Journal of Shandong University(Engineering Science)    2022, 52 (1): 28-38.   DOI: 10.6040/j.issn.1672-3961.0.2020.406
    Abstract113)   HTML2)    PDF(pc) (1920KB)(33)       Save

    Through the wind field simulation, field measurement, wind tunnel test, and the wind-induced vibration of structure under the effect of the domestic and foreign typhoon, the research progresses of four aspects were discussed. This article focused on the great influence people's production and life of all kinds of building structure, based on the structure under the action of typhoon research present situation and the existing problems. The problems that needed to be further studied under the influence of typhoon were prospected.

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    Method for generation planning with the temporal and spatial correlation of wind and solar power
    Wensheng LI,Xian WANG,Yuanze MI,Yongji CAO,Xiaoming LIU,Hengxu ZHANG,Zihan LIU
    Journal of Shandong University(Engineering Science)    2022, 52 (1): 111-119, 127.   DOI: 10.6040/j.issn.1672-3961.0.2020.424
    Abstract110)   HTML2)    PDF(pc) (4265KB)(23)       Save

    A generation planning method considering multi-dimensional spatial-temporal correlation of wind and solar energy was proposed. Based on Copula theory and probability distribution of wind power and photovoltaic, a wind power and photovoltaic output model considering multi-dimensional spatial-temporal correlation of wind power and photovoltaic was established. The output scenario was applied to the bi-level generation planning model, and a generation planning method considering the multi-dimensional spatial-temporal correlation of wind power and photovoltaic was proposed. Among them, the upper level was the investment decision-making model with the minimum total planning cost as the objective function, and the lower level was the short-term operation optimization model with the optimal operation economy and peak shaving characteristics as the objective. The effectiveness of the proposed method was verified by a case study in a certain area, and the influence of the spatial-temporal correlation of wind power and photovoltaic on the generation planning scheme was compared and analyzed.

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    Survey on student academic performance prediction from the perspective of task granularity
    Xiushan NIE,Yuling MA,Huiyan QIAO,Jie GUO,Chaoran CUI,Zhiyun YU,Xingbo LIU,Yilong YIN
    Journal of Shandong University(Engineering Science)    2022, 52 (2): 1-14.   DOI: 10.6040/j.issn.1672-3961.0.2021.489
    Abstract85)   HTML9)    PDF(pc) (1393KB)(52)       Save

    As one of the important research branches in educational data mining domain, student performance prediction was intensively studied. However, a comprehensive review of student performance prediction was still underexplored from the perspective of real applications. This paper detailed the technologies and methods exploited in student performance prediction research from the perspective of task granularity, and then introduced several application-oriented cases of student performance prediction, so as to provide targeted reference information for scientific researchers and educators.

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