电子商务条件下城市物流协同配送车辆路径问题研究

电子商务环境下的协同配送具有客户位置分散、订单多、批量小和重复线路多的特点,通过对当前电子商务条件下的城市协同配送车辆路径问题进行研究,构建了多中心协同配送车辆路径问题的优化模型,并运用自适应遗传算法求解.通过具体实例验证,研究方法较好地提高了配送中心之间的协同工作效率、降低了物流配送成本.

新冠疫情期间大学生学习倦怠与负性情绪的关系:社会支持的中介作用

目的:验证社会支持在学习倦怠与焦虑和抑郁情绪关系中的中介调节作用。方法:2020年4月采用方便抽样的方法利用学习倦怠量表、社会支持量表、抑郁—焦虑—压力量表对某市3所大学的1291名在校生进行问卷调查。结果:新冠疫情期间焦虑、抑郁的检出率分别为56.3%、50.3%,中度焦虑和抑郁占比较大,分别为30.6%、28.0%,焦虑和抑郁的检出在性别方面差异无统计学意义(P>0.05);学习倦怠与焦虑、抑郁之间均存在显著的正相关(r值分别为0.462、0.544,P<0.01),社会支持与学习倦怠、焦虑、抑郁之间均存在负相关(r值分别为-0.153、-0.129、-0.174,P<0.01);学习倦怠能显著负向预测社会支持(回归系数为-0.049,P<0.01),学习倦怠可显著正向预测焦虑和抑郁(回归系数分别为0.323、0.418,P<0.01),加入社会支持之后,学习倦怠仍然能正向预测焦虑和抑郁(回归系数值分别为0.317、0.407,P<0.01),社会支持在学习倦怠和焦虑与抑郁之间起部分中介效应。采用Bootstrap法重复抽样5000次后中介效应均显著(可信区间均不包含0),社会支持在学习倦怠对焦虑情绪和抑郁情绪的中介效应成立,效应量分别为19.81%和29.30%。结论:学习倦怠直接正向预测焦虑和抑郁情绪,并通过社会支持调节降低学习倦怠对焦虑和抑郁的正向影响。

基于改进CMOPSO的前端调速式风电机组优化控制

针对前端调速式风电机组多工况运行、强耦合、结构时变等控制问题,提出一种基于改进CMOPSO算法的变桨变矩优化控制方法.以液力变矩调速装置输出转速波动最小和前端调速式风电机组输出功率波动最小为控制目标建立目标函数,并对机组桨距角和导叶开度进行优化,采用模糊综合评价从非劣解中求取最佳解;以2 MW前端调速式风电机组为对象的仿真验证表明,提出的优化控制策略可实现风电机组的功率控制,可以平滑输出功率,降低功率波动.

基于实测风功率曲线的风电场等值建模

为提高风电场实际运行模型的精确性,采用了基于实测风功率曲线的风电场等值建模方法.该方法运用统计学理论分析了风电场的实测风速及有功功率,得到风电机组的实测风速-功率特性曲线,并利用该曲线得到能够反映风电机组实际输出特性的风力机参数,从而建立了风电机组模型.以实际测得的风速作为分群指标,利用改进型最大树法对风电机组进行分群,进而建立了风电场的等值模型,并与基于风速分群的传统等值方法及风电场实际输出功率曲线进行了对比.仿真结果表明,应用该方法对风电场进行等值建模是有效的,且该模型具有较高的精度.

考虑新能源消纳的源-荷协调多目标优化调度

中国西北地区弃风弃光现象严重,提高新能源消纳能力是电力部门面临的难题.针对此问题,提出了一种考虑新能源消纳的源-荷协调多目标优化调度方法.将负荷聚合商充当整合多种柔性负荷的商户,与常规电源协调参与电网调度,形成源-荷协调运行的优化调度模式.在此基础上,以新能源消纳量最大、系统运行费用最低及火电出力波动最小为优化目标,建立了多目标源-荷优化调度模型,并采用CPLEX对多目标优化模型进行求解.仿真结果验证了该调度方法可以提高新能源消纳能力,降低系统运行成本.

Multi-objective optimization scheduling for new energy power system considering energy storage participation

For the low utilization rate of photovoltaic power generation,taking a new energy power system constisting of concentrating solar power(CSP),photovoltaic power(PP)and battery energy storage system as an example,a multi-objective optimization scheduling strategy considering energy storage participation is proposed.Firstly,the new energy power system model is established,and the PP scenario generation and reduction frame based on the autoregressive moving average model and Kantorovich-distance is proposed.Then,based on the optimization goal of the system operation cost minimization and the PP output power consumption maximization,the multi-objective optimization scheduling model is established.Finally,the simulation results show that introducing energy storage into the system can effectively reduce the system operation cost and improve the utilization efficiency of PP.

华北冷涡背景下青岛三次混合型对流天气环境场条件对比分析

利用探空观测资料,对比分析华北冷涡背景下青岛三次混合型对流天气过程环境场条件,揭示出现短时强降水、雷暴大风和冰雹天气时的水汽、稳定度和垂直风切变差异特征。分析结果表明:500 hPa上冷涡中心位于42°N的华北冷涡、850 hPa低涡系统和偏南风急流以及地面气旋是这三次混合型对流天气的影响系统;在这三次混合型对流过程中有无雷暴大风天气的环境参数区别比较显著:有雷暴大风表现出了相对较干的中低层和中层存在浅薄湿层的水汽层结,无雷暴大风的则是上干下湿和中层大气干燥的层结特征;稳定度差异决定了对流强度的差异:同时出现短时强降水、雷暴大风和冰雹的对流天气的层结不稳定度最强,表现为较大的850和500 hPa温差(大于30℃)以及较强的0~3 km垂直风切变(大于12 m·s^-1);出现短时强降水和大风的大气层结稳定度最弱,相应的环境参数值也最小;在强不稳定层结和低层水汽充足的条件下,大于12 m·s^-1的0~3 km垂直风切变对青岛地区雷暴大风和冰雹的预报预警有较好的指示意义。

基于EQ-5D量表分析老年人高血压患者健康相关生命质量及其影响因素

目的探讨老年人高血压患者的健康相关生命质量(health-related quality of life,HRQoL)状况及影响因素,为提高老年人高血压患者HRQoL提供针对性建议。方法采用多阶段分层整群随机抽样的方法对广州、苏州和青岛的社区老年高血压患者进行问卷调查。单因素分析使用Wilcoxon秩和检验和Kruskal-Wallis H检验,多因素分析使用Tobit回归模型。结果老年人高血压患者健康效用值为0.847(0.569,1.000),在EQ-5D量表的5个维度中的疼痛或不舒服(40.5%)存在的问题最突出。Tobit回归模型结果显示,婚姻状况(已婚:β=0.127,P=0.005<0.05;丧偶:β=-0.069,P=0.003<0.05)和外出频率(1次/d:β=0.106,P<0.001;1次/周:β=0.204,P<0.001;更长时间:β=0.312,P<0.001;不确定:β=-0.423,P<0.001)是影响高血压老年人健康相关生命质量的因素。结论老年人高血压患者生命质量低于普通人群,政府及相关部门可根据主要因素,采取针对性措施,这对提升老年人高血压患者健康相关生命质量具有重要意义。

Peak shaving operation optimization of high proportion new energypower generation considering wind-solar complementationand source-load coupling

To optimize peaking operation when high proportion new energy accesses to power grid,evaluation indexes are proposed which simultaneously consider wind-solar complementation and source-load coupling.A typical wind-solar power output scene model based on peaking demand is established which has anti-peaking characteristic.This model uses balancing scenes and key scenes with probability distribution based on improved Latin hypercube sampling(LHS)algorithm and scene reduction technology to illustrate the influence of wind-solar on peaking demand.Based on this,a peak shaving operation optimization model of high proportion new energy power generation is established.The various operating indexes after optimization in multi-scene peaking are calculated,and the ability of power grid peaking operation is compared whth that considering wind-solar complementation and source-load coupling.Finally,a case of high proportion new energy verifies the feasibility and validity of the proposed operation strategy.

Optimization of solar thermal power station LCOE based on NSGA-Ⅱ algorithm

In view of the high cost of solar thermal power generation in China,it is difficult to realize large-scale production in engineering and industrialization.Non-dominated sorting genetic algorithm II(NSGA-II)is applied to optimize the levelling cost of energy(LCOE)of the solar thermal power generation system in this paper.Firstly,the capacity and generation cost of the solar thermal power generation system are modeled according to the data of several sets of solar thermal power stations which have been put into production abroad.Secondly,the NSGA-II genetic algorithm and particle swarm algorithm are applied to the optimization of the solar thermal power station LCOE respectively.Finally,for the linear Fresnel solar thermal power system,the simulation experiments are conducted to analyze the effects of different solar energy generation capacities,different heat transfer mediums and loan interest rates on the generation price.The results show that due to the existence of scale effect,the greater the capacity of the power station,the lower the cost of leveling and electricity,and the influence of the types of heat storage medium and the loan on the cost of leveling electricity are relatively high.

Vector control of permanent magnet synchronous motor based on dynamic matrix control

Aiming at the control problem of strongly nonlinear and coupled permanent magnet synchronous motor(PMSM)oil rig,this paper presents a predictive control method based on dynamic matrix model.In this method,the dynamic matrix algorithm using multistep prediction technique is applied to the speed loop control of the motor vector control.And its control effect is compared with the traditional proportional integral(PI)control of the motor.By comparing the initial dynamic response and the steady-state recovery under load interference of the two methods,it is shown that the dynamic response and the robustness of the motor controlled by the new method is better than that controlled by conventional PI method.And the feasibility of new control in the application of PMSM oil rig is verified.

Intelligent detection method for workpiece defect based on industrial CT image

In order to solve the problem of internal defect detection in industry, an intelligent detection method for workpiece defect based on industrial computed tomography (CT) images is proposed. The industrial CT slice image is preprocessed first with the combination of adaptive median filtering and adaptive weighted average filtering by analyzing the characteristics of the industrial CT slice images. Then an image segmentation algorithm based on gray change rate is used to segment low contrast information in industrial CT images, and the feature of workpiece defect is extracted by using Hu invariant moment. On this basis, the radial basis function (RBF) neural network model is established and the firefly algorithm is used for optimization, and the intelligent identification of the internal defects of the workpiece is completed. Simulation results show that this method can effectively improve the accuracy of defect identification and provide a theoretical basis for the detection of internal defects in industry.

Lithium battery state of charge and state of health prediction based on fuzzy Kalman filtering

This paper presents a more accurate battery state of charge(SOC)and state of health(SOH)estimation method.A lithium battery is represented by a nonlinear two-order resistance-capacitance equivalent circuit model.The model parameters are estimated by searching least square error optimization algorithm.Precisely defined by this method,the model parameters allow to accurately determine the capacity of the battery,which in turn allows to specify the SOC prediction value used as a basis for the SOH value.Application of the extended Kalman filter(EKF)removes the need of prior known initial SOC,and applying the fuzzy logic helps to eliminate the measurement and process noise.Simulation results obtained during the urban dynamometer driving schedule(UDDS)test show that the maximum error in estimation of the battery SOC is 0.66%.Battery capacity is estimate by offline updated Kalman filter,and then SOH will be predicted.The maximum error in estimation of the battery capacity is 1.55%.

新时代高职院校国际化人才培养的内涵和路径研究

新时代加快了对外开放格局的形成,国际化人才培养契合了"走出去"战略、大数据时代和跨界融合的需要,其内涵包含开放性理念、"互联网+"理念和服务性理念。高职院校要通过重塑人才培养规格、打造优质教学资源、携手政行企以及深化国际合作,来保障国际化人才的培养。

不同掺合料对混凝土性能的影响研究

研究了以石灰石粉和粉煤灰为掺合料的混凝土性能及其差异。试验结果表明:在一定掺量范围内,石灰石粉可用做混凝土掺合料,拌制出力学性能和耐久性能满足设计要求的混凝土。但与掺粉煤灰混凝土相比,掺石灰石粉混凝土的单位用水量会增大,其早期抗压强度、抗拉强度、弹模和极限拉伸值发展较快,28d龄期后增长幅度较小,且掺石灰石粉混凝土在一定龄期后的干缩和自生体积变形都要较掺粉煤灰混凝土更大。

不同级配及组合骨料的混凝土配合比研究及工程应用

骨料约占混凝土总体积的3/4,其性质对混凝土的变形性能、力学性能及耐久性等都有重要的影响,规范中对水工混凝土骨料的级配及品质提出了要求,但根据实际料源供应情况,有时需考虑非水工骨料在水电站工程中的应用。结合桐子林水电站导流明渠工程,通过对比分析,研究了不同骨料比例、不同骨料级配对于混凝土配合比参数及其强度的影响,及非水工级配及组合骨料在该工程中的应用情况。

An optimal strategy for coordinating and dispatching “source-load” in power system based on multiple time scales

Due to the phenomenon of abandoning wind power and photo voltage(PV)power in the“Three Northern Areas”in China,this paper presents an optimal strategy for coordinating and dispatching“source-load”in power system based on multiple time scales.On the basis of the analysis of the uncertainty of wind power and PV power as well as the characteristics of load side resource dispatching,the optimal model of coordinating and dispatching“source-load”in power system based on multiple time scales is established.It can simultaneously and effectively dispatch conventional generators,wind plant,PV power station,pumped-storage power station and load side resources by optimally using three time scales:day-ahead,intra-day and real-time.According to the latest predicted information of wind power,PV power and load,the original generation schedule can be rolled and amended by using the corresponding time scale.The effectiveness of the model can be verified by a real system.The simulation results show that the proposed model can make full use of“source-load”resources to improve the ability to consume wind power and PV power of the grid-connected system.

Dynamic reactive power planning method for CSP-PV hybrid power generation system

Aiming at the faults of some weak nodes in the concentrated solar power-photovoltaic(CSP-PV)hybrid power generation system,it is impossible to restore the transient voltage only relying on the reactive power regulation capability of the system itself.We propose a dynamic reactive power planning method suitable for CSP-PV hybrid power generation system.The method determines the installation node of the dynamic reactive power compensation device and its compensation capacity based on the reactive power adjustment capability of the system itself.The critical fault node is determined by the transient voltage stability recovery index,and the weak node of the system is initially determined.Based on this,the sensitivity index is used to determine the installation node of the dynamic reactive power compensation device.Dynamic reactive power planning optimization model is established with the lowest investment cost of dynamic reactive power compensation device and the improvement of system transient voltage stability.Furthermore,the component of the reactive power compensation node is optimized by particle swarm optimization based on differential evolution(DE-PSO).The simulation results of the example system show that compared with the dynamic position compensation device installation location optimization method,the proposed method can improve the transient voltage stability of the system under the same reactive power compensation cost.

Analysis of grid-connected voltage stability of FSCWT based on bifurcation theory

This paper studies on the change mechanisms of the voltage stability caused by the grid connection of front-end speed-controlled wind turbines(FSCWT)integrating into power system.First of all,the differential algebraic equations describing the dynamic characteristics of wind turbines are illustrated.Then,under the guidance of IEEE3 node system model,the influence of the angular velocity of wind turbines,the reactive power and the active power at load bus on the voltage stability of grid-connection has been analyzed by using bifurcation theory.Finally,the method of linear-state feedback control has been applied to the original system in accordance with the bifurcation phenomenon of grid-connected voltage caused by the increase in the active power at load bus.Research shows that voltage at the grid-connected point would be changed with the fluctuation of turbines angular velocity.And increasing its reactive power can enhance voltage at the grid-connected point;problem of bifurcation at the grid-connected point can be delayed when increasing the gain k s of feedback controller within a certain range.

双掺料在某水电站碾压混凝土中的应用研究

为了利用某水电站附近电厂堆灰场的灰渣和磷矿渣,对磨细灰渣和磷渣进行了混掺(简称双掺料),对掺双掺料和掺粉煤灰的胶砂性能,碾压混凝土力学、变形、耐久性能及热学性能进行了对比试验分析,结果表明双掺料可用作碾压混凝土的掺合料。