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    Impact analysis of road traffic on urban air quality in congested environment
    FENG Haixia, WANG Qi, YANG Licai, KOU Junying, XIE Qingmin, ZHAO Junxue, MENG Xianglu, WANG Yanfeng
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 128-134.   DOI: 10.6040/j.issn.1672-3961.0.2020.211
    Abstract450)      PDF(pc) (3465KB)(145)       Save
    Focusing on research hot issues of traffic congestion, haze(air quality), and the main urban area of Jinan taken as an example, the paper quantitatively analyzed the impact of peak congestion delay index and traffic operation index on urban air quality. Combining with satellite retrieval of aerosol optical depth(AOD ), the impact of road traffic on air quality in congestion environment was quantitatively analyzed based on geographical weighted regression model. The results showed that there was a strong correlation between the peak congestion delay index and the air quality index. The traffic operation had great influence on air quality. Geographically weighted regression(GWR)refined local spatial features. Under traffic congestion conditions, the road area occupancy rate had the greatest impact on air quality in the region. The paper had certain guiding significance for traffic planning and provided support for traffic planning and control.
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    Optimal structure of pressure cast-situ-pile with spray-expanded frustum
    Lianxiang LI,Hongxia XING,Jinliang LI,Hengli HUANG,Lei WANG
    Journal of Shandong University(Engineering Science)    2020, 50 (6): 82-91.   DOI: 10.6040/j.issn.1672-3961.0.2020.090
    Abstract383)   HTML22)    PDF(pc) (6556KB)(73)       Save

    According to the field test results of pressure cast-situ-pile with spray-expanded frustum, with the help of Abaqus to establish the numerical model of the experiment, the influence rule of expanded body with frustum (hereinafter referred to as frustum) on surrounding soil under vertical load was obtained. It was clarified that the soil mass had squeezing effect within the 2D~3D range (D is frustum's diameter) and it reached the limit at 0.5 m under the frustum. Stress relaxation occured in the upper soil of frustum, which reached the limit value at the top of the frustum, and of which the vertical influence range was extended by 1.25D and the horizontal influence range was 1.5D~2.5D. Revealed that the optimal spray angle for frustum expanding was 50°~55°, the optimum expanding ratio was 2~2.75, the optimal position was in the D~2D range of upper part of pile, and it was optimal when the fixed spray wing was 7~8 m below the pile top. The optimal construction model could increase the bearing capacity by 19%, therefore it was suggested to adopt the optimal structural pile type to further improve efficiency and promote application of the pile.

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    Eye tracking in human-computer interaction control
    Hui HE,Junhao HUANG
    Journal of Shandong University(Engineering Science)    2021, 51 (2): 1-8.   DOI: 10.6040/j.issn.1672-3961.0.2020.346
    Abstract374)   HTML36)    PDF(pc) (4362KB)(176)       Save

    To actualize the simple and low-cost eye-tracking based human-computer interaction, an exact interaction method based on the visual directions estimation and eye tracking with webcam videos was proposed. A simple and fast convolution neural network model was used to roughly estimate the user′s viewpoints on the screen. And then an accurate human-computer interaction method was proposed on the basis of the eye movements recognition and sight line tracking results. To verify the effectiveness of the method, the key operations of eye mouse and eye typing were developed. The test results show that the proposed method enabled users to achieve eye tracking and to actualize most precise human-computer interactions with only one common monocular camera, which was expected to completely replace the mouse and keyboard hardwares.

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    Overview of multi-motion vision odometer
    Fengyu ZHOU,Panlong GU,Fang WAN,Lei YIN,Jiakai HE
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 1-10.   DOI: 10.6040/j.issn.1672-3961.0.2020.382
    Abstract362)   HTML381)    PDF(pc) (3543KB)(187)       Save

    Multi-motion visual odometry (MVO) was an algorithm for estimating the pose change of dynamic objects in dynamic scenes. It was of great theoretical significance and practical value in autonomous things (AuT). The development process and the latest research progress of multi-motion visual odometer in robot field were reviewed. The important research results of multi-motion visual odometer with the fusion of semantic and geometric features were introduced. Based on the same evaluation criteria and datasets, this research compared several common methods, and prospected the future development direction of multi motion visual odometer.

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    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
    Abstract361)   HTML136)    PDF(pc) (6369KB)(302)       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.

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    Design pattern classification mining with feature metrics constraints
    Zhuoyu XIAO,Pei HE,Guo CHEN,Yunbiao XU,Jie GUO
    Journal of Shandong University(Engineering Science)    2020, 50 (6): 48-58.   DOI: 10.6040/j.issn.1672-3961.0.2020.229
    Abstract330)   HTML25)    PDF(pc) (1397KB)(117)       Save

    To solve low accuracy for design pattern mining, a method for design pattern classification mining with feature metrics constraints was presented. 47 feature metrics information based on structural pattern, behavioral pattern and creative pattern was classified and summarized, and definition of design pattern were given, and features of design patterns were described, three benchmark systems and four well-known system experiments for design pattern mining were designed. Experimental results show that proposed method is effective, and the accuracy of the proposed method was 96.13%, 91.67%, 72.23% for Adapter pattern. Command pattern and Factory method pattern for three benchmark systems, and the accuracy of the proposed method is 84.3%, 81.26%, 73.17% for Adapter, Command and Factory Method of design pattern for four well-known systems, compared to well-known methods by experiment of design pattern mining, indicating the effectiveness of the proposed method.

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    Electric vehicle virtual energy storage available capacity modeling
    Bei LI,Song ZHAO,Zhijia XIE,Meng NIU
    Journal of Shandong University(Engineering Science)    2020, 50 (6): 101-111.   DOI: 10.6040/j.issn.1672-3961.0.2020.128
    Abstract326)   HTML22)    PDF(pc) (2357KB)(109)       Save

    In order to efficiently implement the virtual energy storage dispatch of electric vehicles in a wide area, the article focused on the types of electric vehicles that respond to electric vehicle virtual energy storage (EVVES) services by clustering, combined with the use habits of all kinds of electric vehicle owners (such as daily driving mileage, charging and discharging rules, expected standby travel electricity, etc.), the impact of market on EVVES responsiveness, redundant design of available energy storage capacity and other factors, a virtual energy storage (VES) capacity estimation model was established. Combined with the technical requirements of power system for energy storage to participate in system services, such as emergency power support, smooth renewable energy output, UPS/EPS, etc., the matching basis of supply and demand was proposed. Based on Monte Carlo simulation method, the practicability of the model to estimate the available capacity of response VES service in different time periods was verified, which layed the foundation for the operation practice of EVVES in future.

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    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
    Abstract294)   HTML19)    PDF(pc) (6074KB)(113)       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.

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    Law of horizontal deformation displacement of tunnels due to adjacent excavation
    LI Lianxiang, ZHANG Qiang, SHI Jinjiang, LIU Jiadian, HOU Yingxue
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 46-52.   DOI: 10.6040/j.issn.1672-3961.0.2020.340
    Abstract280)      PDF(pc) (1666KB)(126)       Save
    The horizontal displacement of the tunnel hance was divided into three parts. Based on the change of horizontal coefficients of subgrade reaction, the paper proposed the concept of “horizontal deformation displacement”, which was analyzed by the PLAXIS 3D. And the correlation formula between the maximum horizontal deformation displacement and the foundation pit width and the horizontal distance was obtained by fitting. The results showed that the horizontal deformation displacement decreased exponentially with the increase of the horizontal distance between the tunnel and the foundation pit, and the influence of the foundation pit width was ignored when the value of the horizontal distance was greater than the depth of the foundation pit. The formula derived in this paper could be used to calculate the horizontal convergence value of the tunnel adjacent to the excavation, the horizontal displacement of the tunnel hance, and the horizontal coefficients of subgrade reaction near the tunnel.
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    Ultimate uplift capacity of shallow vertical plate anchors in sand
    Xiuguang SONG,He YANG,Xiaoyan CHEN,Wenjie CUI,Hongya YUE,Kai ZHANG,Juan TIAN
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 24-31, 38.   DOI: 10.6040/j.issn.1672-3961.0.2020.265
    Abstract261)   HTML122)    PDF(pc) (5430KB)(101)       Save

    This paper investigated the pullout behaviour of shallow vertical plate anchors in sand. Pull-out model tests were performed using the particle image velocimetry (PIV) technology, by which the soil deformation and failure mechanisms were observed. Then the ultimate bearing capacity of vertical plate anchors at various soil properties and cover depths was simulated using the finite element limit analysis software. According to the observed failure mechanism, a limit equilibrium solution was developed to calculate the bearing capacity of shallow strip plate anchors in sand, which was then extended for the prediction of the ultimate bearing capacity of rectangle plate anchors by introducing a shape coefficient. Results predicted by the new limit equilibrium solution showed close agreement with those by the lower bound limit analysis solution. The limit equilibrium solution was compared with 51 experimental data, which showed an average of 5% overestimation of the ultimate bearing capacity. This research can provide a theoretical method for the calculation of the ultimate bearing capacity of shallow plate anchors in sand.

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    Study on offshore wind farm overvoltage and reactive power compensation
    XU Dapeng, CAI Deyu, ZHAO Lanming, LIU Xumin
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 94-99.   DOI: 10.6040/j.issn.1672-3961.0.2020.393
    Abstract260)      PDF(pc) (5532KB)(107)       Save
    This paper presented a new methodology for offshore wind farm grid-connection overvoltage and reactive power compensation. The methodology used DIgSILENT PowerFactory software for offshore wind farm modelling, including wind turbine, submarine cable, transformer and relevant control schemes. Moreover, dynamic simulations was performed in time-domain to analyze the active power, reactive power and voltage characteristics of the wind farm under different wind speed conditions. According to the results of the simulations, reactive power compensation devices were configured, and consequently the voltage and power factor condition of the offshore wind farm would be improved, which was also verified by the simulation results.
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    Journal of Shandong University(Engineering Science)    2021, 51 (1): 76-86.   DOI: 10.6040/j.issn.1672-3961.0.2020.416
    Abstract258)      PDF(pc) (14390KB)(74)       Save
    This paper proposed a method to calculate an active power coefficient of the zero-sequence signal in the frequency band below 80 Hz. The coefficient was defined the ratio of active to apparent power within a fixed time window. This method identified the fault direction through the polarity and absoluted value of the coefficient. Digital simulation and actual fault recordings data had verified the feasibility of the proposed method, which could trip reliably for high impedance faults, and avoid the current transformer error.
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    MIRGAN: a medical image report generation model based on GAN
    Junsan ZHANG,Qiaoqiao CHENG,Yao WAN,Jie ZHU,Shidong ZHANG
    Journal of Shandong University(Engineering Science)    2021, 51 (2): 9-18.   DOI: 10.6040/j.issn.1672-3961.0.2020.227
    Abstract253)   HTML38)    PDF(pc) (2295KB)(93)       Save

    The medical image report generation task based on image understanding became a widely concerned issue. Compared with the traditional image understanding task, medical image report generation was a more challenging task. We proposed a medical image report generative adversarial network (MIRGAN) model for this task. A co-attention mechanism was adopted to synthesize the visual and semantic features of multiple feature areas and generate descriptions corresponding to these areas. Combining the generative adversarial networks (GAN) and reinforcement learning (RL) optimized the performance of the generative model to output higher quality reports. The experiment results demonstrated the effectiveness of our proposed MIRGAN model.

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    True mechanical model of underground pipe corridor supported by piles
    LI Lianxiang, WANG Lei, ZHAO Yongxin, JI Xiangkai
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 60-68.   DOI: 10.6040/j.issn.1672-3961.0.2020.294
    Abstract245)      PDF(pc) (4922KB)(86)       Save
    In order to study the influence of the pile support system on the real mechanical model of the pipe gallery structure, taking an underground comprehensive pipe gallery project in Jinan as an example, the whole process of the project was simulated by using the Plaxis 3D finite element software. It was found that the stress on the side plate of the underground pipe gallery under the pile support was distributed in three sections: first increase, then decrease, then increase, and obviously less than the static earth pressure, and the internal force of the side plate of the pipe gallery was less than the traditional square law. According to the simulation results, the stress distribution curve and its simplified curve of the side plate of the pipe gallery were obtained by changing the thickness of the covered soil on the top of the gallery. The calculation results showed that the internal force of the side plate of the pipe gallery calculated by the simplified curve was in good agreement with the simulation value, that was to say, the simplified curve had better applicability. According to the simplified curve to calculate the side load of the pipe gallery, the designed pipe gallery structure was more practical, economic and reasonable.
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    Day-ahead optimal scheduling considering the constraints of UHVDC transmission and wheeling contracts
    Dexin LI,Chonglin ZONG,Jiarui WANG,Haifeng ZHANG,Chang LIU,Dawei HUANG
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 69-75, 86.   DOI: 10.6040/j.issn.1672-3961.0.2020.361
    Abstract241)   HTML12)    PDF(pc) (3689KB)(69)       Save

    The operational characteristics of ultra-high voltage direct current (UHVDC) transmission and the impact of wheeling contracts on power grid operation and dispatching were analyzed, and a grid-optimized dispatching model considered the constraints of UHVDC transmission and inter-subnet wheeling contracts was established. The model aimed at the minimum operating cost of the power grid and the minimum of wind and photovoltaic curtailment, at the same time, the power constraints of the transmission and wheeling of AC and DC lines were considered, by adding two types of 0-1 variables that characterize power regulation, power up and power down, the stepped constraints of UHVDC transmission lines were expressed as linear equations of 0-1 mixed integers. Taking the improved IEEE39 node system as an example, the impact of UHVDC transmission and wheeling contracts on the grid′s renewable energy consumption was analyzed, and the effectiveness of the proposed method was verified.

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    Real-time semantic segmentation of high-resolution remote sensing image based on multi-level feature cascade
    Chunhong CAO,Hongxuan DUAN,Ling CAO,Lele ZHANG,Kai HU,Fen XIAO
    Journal of Shandong University(Engineering Science)    2021, 51 (2): 19-25.   DOI: 10.6040/j.issn.1672-3961.0.2020.225
    Abstract238)   HTML29)    PDF(pc) (4639KB)(109)       Save

    Aiming at the problems of long segmentation time and inaccurate segmentation of small targets in remote sensing image semantic segmentation, a fast semantic segmentation model of high-resolution remote sensing image based on multi-level feature cascade network (MFCNet) was proposed. The model was mainly composed of feature encoding, feature fusion and target refinement. Feature encoding extracted the input images feature of different resolutions and used different backbone networks. Due to the lower resolution of low-resolution images, heavy-weight backbone networks were used to obtain rich semantic information with fewer parameters. For medium and high-resolution images, lightweight backbone network was used to reduce the amount of parameters and obtain global information. While medium and low-resolution encoding used the way of weights and calculation sharing to further reduce model parameters and computational complexity. The feature fusion section fused features from different branches to obtain information at different scales. The target refinement used residual to correction the fused features and the features of the coded part to restore the spatial detail information of the image, making the segmentation more accurate. And the entire model worked efficiently in an end-to-end manner. The experimental verified the validity of the model in semantic segmentation of remote sensing images, and achieved a good balance between model complexity and accuracy.

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    Influence of TBM tunnel excavation at different positions on buildings
    SUN Jie, WU Ke, ZHENG Yang, LI Shuchen, YUAN Chao, WANG Xiuwei
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 32-38.   DOI: 10.6040/j.issn.1672-3961.0.2020.331
    Abstract237)      PDF(pc) (8680KB)(114)       Save
    In view of the settlement and deformation of existing buildings induced by TBM(tunnel boring machine)tunnel excavation of urban subway, considering the complexity of the actual working conditions of tunnel undercrossing urban buildings, taking the TBM tunnel tunneling in hard rock stratum of Xiaobei Section of Qingdao Metro Line 1 as the actual engineering background, the numerical calculation method was adopted to establish the continuous tunneling of TBM tunnel through several existing buildings. Based on the engineering construction practice, the spatial attribute characteristics of TBM tunnel were systematically studied. The stress-strain state of ground layer and existing buildings induced by TBM tunnel double tunnel driving under existing buildings were studied systematically. The research results showed that the shallower the tunnel depth was, the greater the settlement rate of the buildings affected by the tunnel excavation. In the excavation of double track tunnel, the larger the proportion of buildings affected by the excavation of the tunnel with shorter transverse distance, the greater the tunnel buried depth, the greater the influence of the superposition of double tunnels. When the tunnel passed through the irregular building, it had great influence on the corner of the building and the small building near the large-scale building, so it needed to be monitored in the actual construction.
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    Influence of shear span ratio on seismic performance of hollow pipe pier with slot connection
    SU Sibo, WANG Guoqing, JIA Xianzhuo, LI Zhicong, HUANG Zhigang
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 39-45.   DOI: 10.6040/j.issn.1672-3961.0.2020.387
    Abstract233)      PDF(pc) (7608KB)(74)       Save
    In order to study the influence of shear span ratio on seismic performance of slotted pipe pier with grouted core, based on the bridge engineering of Rongwu New Line Highway, ABAQUS finite element analysis software was used to simulate three kinds of slotted connection pipe pier with different shear span ratio, and the full-scale model of slotted connection pipe pier were made, and the horizontal cyclic load test under constant axial force was carried out to verify the reliability of the finite element model. The results showed that the failure modes of three different shear span ratios were shear failure, bending shear failure and bending failure. With the increase of shear span ratio, the hysteretic performance, energy dissipation capacity and ductility performance of the pipe pier had been significantly improved, but its bearing capacity and residual displacement had little change, the initial stiffness had been strengthened, but the ultimate failure stiffness were basically the same.
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    Multi-kernel combination method based on rank spatial difference
    WANG Mei, XUE Chenglong, ZHANG Qiang
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 108-113.   DOI: 10.6040/j.issn.1672-3961.0.2020.248
    Abstract230)      PDF(pc) (444KB)(82)       Save
    A multi-kernel combination method based on rank spatial difference was proposed in this paper. samples were grouped according to characteristics, different kernel functions are used to train the grouped data, and the parameters of the kernel function are optimized by grid search method. Two kernel functions were selected from the alternative kernel functions, and the data divided into two groups were respectively put into the corresponding kernel function for mapping. Then the rank spatial difference of the data after the kernel function mapping was judged to provide reference for the selection of the basic kernel function. The wine data set, the breast cancer data set and the wine quality data set were selected for the experiment to verify that when the data were mapped by the selected basic kernel function, the greater the rank space difference was, the higher the classification accuracy was. The experimental results showed that the method was feasible for the selection and combination of basic kernel functions.
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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
    Abstract229)   HTML520)    PDF(pc) (4584KB)(87)       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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    Multiobjective dynamic economic emission dispatch differential evolution algorithm based on elites cloning local search
    WU Huihong, QIAN Shuqu, LIU Yanmin, XU Guofeng, GUO Benhua
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 11-23.   DOI: 10.6040/j.issn.1672-3961.0.2020.050
    Abstract213)      PDF(pc) (5001KB)(92)       Save
    An efficient multiobjective differential evolution algorithm based on elites cloning local search scheme was proposed to solve complex dynamic economic emission dispatch. The conventional differential evolution(DE)algorithm was used as the framework of the proposed algorithm. A cloning operator was developed to enhance the exploration and exploitation ability of elites in the DE algorithm. The elite population to be cloned was established by a dynamic selection mechanism for enhancing the global search ability of the proposed algorithm. To validate the effectiveness of the proposed algorithm, the IEEE 30 bus 10-generator and 15-generator systems were studies as test cases in numerical experiments. The simulation results indicated that the Pareto-optimal front obtained by the proposed algorithm presented a superior performance in convergence and extension over the other reported results recently. As a result, the results were able to provide decision solutions more extensively for decision-makers in power system dispatch.
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    Calculation method of the single-double angle joints in transmission towers
    XU Zaigen, LIU Zhengwei, LIU Wenpeng, ZHOU Mengyao, LIU Juncai, TIAN Li
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 87-93.   DOI: 10.6040/j.issn.1672-3961.0.2020.437
    Abstract206)      PDF(pc) (8478KB)(74)       Save
    The adoption of combined double angle steel in the lower part of single angle steel as the main material was a common method to effectively improve the bearing performance of the transmission tower, which was conducive to clarifying the force transmission path between variable sections while ensuring high material utilization. However, there were still lack of systematic research and blank in the calculation codes for such joints. Consequently, based on the actual project, 5 typical single-double angle steel joints were selected and modelled in ABAQUS software. The bearing capacity characteristics and force transmission mechanism of the joints were analyzed through numerical simulation. Considering that the bending moment was the main factor affecting the performance of the horizontal plate, different single-double angle steel joints were simulated by changing the eccentricity. The bending moment adjustment factor and the bending moment enhancement factor were raised as the main control parameters in the horizontal plate thickness calculation formula.
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    Novel guidewire modeling method based on Energy minimum theory
    WANG Yu, LIU Hao
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 114-119.   DOI: 10.6040/j.issn.1672-3961.0.2020.364
    Abstract192)      PDF(pc) (4431KB)(91)       Save
    A high-performance guidewire model was demanded in the VR(virtual reality, VR)training system for endovascular interventional surgery. A new guidewire modeling method was proposed. This method used a cylindrical rigid body with hemispherical ends as the basic unit of the guidewire and the geometric characteristics of the model itself combined the principle of minimum energy to obtain the guidewire deformation parameters when the guidewire was inserted into the target blood vessel branch, which improved the accuracy and flexibility of the guidewire. Combined with the developed guidewire manipulator, the established guidewire achieved good performance and keeped synchronization with it during the experiment, which helped novices to immerse in the training environment.
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    Emission characteristics of PM1.0-bound polycyclic aromatic hydrocarbons(PAHs)from different stoves and fuels in rural areas
    DUAN Shengfei, YANG Lingxiao, LI Jingshu, GAO Hongliang, ZHANG Wan, ZHANG Xiongfei, QI Anan, WANG Pengcheng, WANG Yiming, TUO Xiong
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 120-127.   DOI: 10.6040/j.issn.1672-3961.0.2020.513
    Abstract186)      PDF(pc) (4446KB)(80)       Save
    To study the emission factors and emission characteristics of PM1.0-bound PAHs from the combustion of different fuels and improve stoves in rural areas, the samples produced by 8 fuels burned in 2 improved stoves were collected using the dilution channel method, and the concentration of PAHs was analyzed. The results showed that the emission factor was in the range of 0.38~39.37 mg·kg-1. When the same fuel was burned in different improved stoves, the gasifier stoves emission factor of PAHs was lower than the decoupling stoves. The order of PAHs emission factors of various fuels burned in the gasifier stove was EFbulk coal>EFcorn straw>EFbituminous coal briquette>EFpine wood>EFoak wood>EFsemi-coal≈ EFanthracite briquette>EFcorn straw briquette. Among biomass fuels, PHE, PLA, and PYR were the main species of PAHs produced by combustion, while the dominant species in coals were PHE, FLA, PYR, and BbF. The proportion of LMW PAHs produced by the gasifier stove was higher than the decoupling stove, while the proportion of MMW PAHs and HMW PAHs produced by the gasifier stove was lower than the decoupling stove. In the case of meeting the heating demand of residents, it was estimated that the best combination was gasifier stove+semi-coke, anthracite briquette, or corn straw briquette.
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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
    Abstract186)      PDF(pc) (6868KB)(170)       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
    Abstract172)   HTML135)    PDF(pc) (2767KB)(25)       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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    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
    Abstract169)      PDF(pc) (6150KB)(60)       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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    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
    Abstract167)      PDF(pc) (3912KB)(87)       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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    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
    Abstract166)      PDF(pc) (8916KB)(48)       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
    Abstract164)      PDF(pc) (5863KB)(52)       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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    Experimental study on stiffness of reinforced concrete pre-cracked beams based on crack parameters
    ZHOU Shuming, YAN Donghuang
    Journal of Shandong University(Engineering Science)    2021, 51 (1): 53-59.   DOI: 10.6040/j.issn.1672-3961.0.2020.403
    Abstract161)      PDF(pc) (1794KB)(67)       Save
    To research the stiffness characteristics of simply-supported reinforced concrete bridges after cracking in the mid-span, mechanical tests of pre-cracked in the mid-span beams with different nominal damage ratios were carried out. The specimens were cast-in-situ reinforced concrete pre-cracking beams. In the specimens, three different lengths(a=8、18 and 26 mm)of cracks in the mid-span were considered respectively. The evolutions of stiffness reduction coefficient k with nominal damage ratio λ and crack opening w under load of the 8 m standard span reinforced concrete pre-cracked beams were studied through experiments. It was showed that under different test conditions, k decreased with the increase of λ and w. The pre-cracked specimensk decreased little when the crack length was less than the thickness of the protective layer of reinforcement, decreased rapidly when the crack length was near the height of reinforcement. However, the decreased speed appears to fall back when the crack length was higher than the height of the reinforcement. On this basis, a formula for calculating the stiffness reduction coefficient of simply-supported reinforced concrete bridges after cracking in the mid-span was proposed. The effort of this paper could provide a basic for the accurately predicting and evaluating the stiffness characteristics of simply-supported reinforced concrete bridges after cracking.
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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
    Abstract159)   HTML166)    PDF(pc) (8639KB)(34)       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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    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
    Abstract158)      PDF(pc) (3119KB)(62)       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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    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
    Abstract155)      PDF(pc) (2199KB)(38)       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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    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
    Abstract155)   HTML71)    PDF(pc) (4005KB)(59)       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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    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
    Abstract151)      PDF(pc) (1618KB)(26)       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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    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
    Abstract150)      PDF(pc) (2317KB)(52)       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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    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
    Abstract146)   HTML74)    PDF(pc) (2986KB)(43)       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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    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
    Abstract144)      PDF(pc) (3951KB)(32)       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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    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
    Abstract140)   HTML175)    PDF(pc) (3853KB)(30)       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
    Abstract136)      PDF(pc) (4454KB)(32)       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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    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
    Abstract128)   HTML8)    PDF(pc) (4939KB)(76)       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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    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
    Abstract120)   HTML3)    PDF(pc) (5138KB)(23)       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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    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
    Abstract116)   HTML7)    PDF(pc) (9207KB)(33)       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
    Abstract116)      PDF(pc) (4805KB)(17)       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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    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
    Abstract113)   HTML10)    PDF(pc) (2283KB)(28)       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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    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
    Abstract102)   HTML78)    PDF(pc) (7930KB)(46)       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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    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
    Abstract93)   HTML1)    PDF(pc) (4232KB)(20)       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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    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
    Abstract92)   HTML9)    PDF(pc) (4892KB)(27)       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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    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
    Abstract90)   HTML7)    PDF(pc) (1810KB)(26)       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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