新能源汽车上市公司投资效率评价研究——基于DEA和Malmquist指数模型

以新能源汽车上市公司为研究对象,运用DEA模型和Malmquist指数法,从静态和动态双视角分析和评价新能源汽车行业的投资效率。静态结果表明：2017—2021年,我国新能源汽车上市公司的投资效率整体水平较高但呈现下降趋势,综合效率值接近于1,其主要源于纯技术效率的贡献。动态结果表明：样本公司的全要素生产率小于1,其主要原因为技术效率指数较低。据此,新能源汽车公司应增强研发能力、注重人才培养、强化成本管控、加强市场营销和品牌建设,以提升投资效率。     

有时间窗车辆路径问题的模型及其改进模拟退火算法研究

论文在对有时间窗车辆路径问题进行描述的基础上,建立了该问题的基于直观描述的数学模型.论文还根据有时间窗车辆路径问题的特点构造了求解该问题的改进模拟退火算法,并进行了实验计算.计算结果表明,用本文设计的改进模拟退火算法求解有时间窗车辆路径问题,不仅可以取得很好的计算结果,而且算法的计算效率较高,收敛速度较快,计算结果也较稳定.     

Hybridization of tabu search with feasible and infeasible local searches for periodic home health care logistics

This paper addresses a periodic vehicle routing problem encountered in home health care (HHC) logistics. It extends the classical Periodic Vehicle Routing Problem with Time Windows (PVRPTW) to three types of demands of patients at home. Demands include transportation of drugs/medical devices between the HHC depot and patients׳ homes, delivery of special drugs from the hospital to patients, and delivery of blood samples from patients to the lab. Each patient requires a certain number of visits within a planning horizon and has a set of possible combinations of visit days. Daily routing should meet time window constraints associated with patients, the hospital and the lab. The problem consists in determining the visit days of each patient and vehicle routes for each day in order to minimize the maximal routing costs among all routes over the horizon. We propose a Tabu Search method combined with different local search schemes including both feasible and infeasible local searches. The proposed approaches are tested on a range of instances derived from existing Vehicle Routing Problem with Time Window (VRPTW) benchmarks and benchmarks on special cases of our problem. Numerical results show that local search scheme starting with an infeasible local search with a small probability followed by a feasible local search with high probability is an interesting hybridization. Experiments with field data from a HHC company show that the proposed approach reduces the total cost and better balances the workloads of vehicles.     

Study on Multi-Trip Vehicle Routing Problem with Stochastic Simultaneous Pickup-Delivery Demand

Characterized by high service efficiency and low vehicle cost, multi-trip distribution allows the vehicle to travel multiple times between the distribution center and customers in order to complete the delivery task. Dynamic and uncertain customer demand is common during delivery. Combined pickup-delivery integration pattern with stochastic customer demand, an optimization model for multi-trip vehicle routing problem is set up with stochastic simultaneous pickup-delivery demand. Due to the sudden and simultaneous pickup-delivery of dynamic demand, the original distribution scheme needs to be optimized and adjusted, and the multi-trip routing adjustment strategy of "real-time flexible point" is proposed. According to the stochastic characteristics of the optimization model, a stochastic chance-constrained programming transformation model is introduced. A hybrid algorithm with nested stochastic simulation and variable neighborhood tabu search algorithm is designed to find the optimal distribution path. Finally, an example shows that the optimization model and algorithm are feasible and effective.     

Vehicle Emission Unit Risk Factors for Transportation Risk Assessments

When the transportation risk posed by shipments of hazardous chemical and radioactive materials is being assessed, it is necessary to evaluate the risks associated with both vehicle emissions and cargo-related risks. Diesel exhaust and fugitive dust emissions from vehicles transporting hazardous shipments lead to increased air pollution, which increases the risk of latent fatalities in the affected population along the transport route. The estimated risk from these vehicle-related sources can often be as large or larger than the estimated risk associated with the material being transported. In this paper, data from the U.S. Environmental Protection Agency's Motor Vehicle-Related Air Toxics Study are first used to develop latent cancer fatality estimates per kilometer of travel in rural and urban areas for all diesel truck classes. These unit risk factors are based on studies investigating the carcinogenic nature of diesel exhaust. With the same methodology, the current per-kilometer latent fatality risk factor used in transportation risk assessments for heavy diesel trucks in urban areas is revised and the analysis expanded to provide risk factors for rural areas and all diesel truck classes. These latter fatality estimates may include, but are not limited to, cancer fatalities and are based primarily on the most recent epidemiological data available on mortality rates associated with ambient air PM-10 concentrations.     

图像处理技术在乘用车侧面碰撞试验中的应用

多媒体计算机序列图像运动分析系统与摄影测量学理论相结合,成为较完善的非接触动态测量系统.在乘用车侧面碰撞试验中采用图像采集和数字图像处理技术,结合直接线性变换(direct liner transformation,DLT)算法,分析碰撞试验中标示点的变形量,提高乘用车侧面碰撞强度,为汽车被动安全性研究提供依据.     

电动汽车自动变速器设计研究

由于电池和电机技术的不成熟,电动汽车仍需利用变速器提高整车动力性和经济性。本文首先简述了常见自动变速器的结构原理和优缺点,结合电动汽车电机特性和双离合器自动变速器的优点,提出将两挡双离合器自动变速器应用于电动汽车,并着重对该自动变速器的系统结构原理及其实现过程进行介绍,并分析了该自动变速器的优点。经研究表明,两挡自动变速器具有较好的应用前景。     

产品方案设计与评价一体化系统集成技术

在产品设计过程中，方案设计与评价的系统集成是技术关键。以履带车辆设计评价集成为例，给出其设计方法，采用J2EE平台技术，实现基于Web的履带车辆设计评价一体化系统。管理员可通过web添加任意层次的评价指标和待评价的设计方案，Web服务器上集成了多种评价方法，专家可选择一种或几种方法对方案分别进行评价，采用VRML显示待评价的三维设计方案，专家可在线修改设计方案并加以评价。应用结果表明，使用本系统可有效提高设计效率。     

重型特种汽车营销网络体系

为探索重型特种汽车的发展战略，构建现代市场营销网络体系，应对日益激烈的市场竞争，通过市场调研、数据收集和统计图表分析方法，对其现行营销模式、销售渠道、营销网络的特点和缺陷进行分析。分析认为：应对现行营销网络体系进行重新整合和改进，新的营销网络体系由经销网点、机电进出口公司和自建销售公司构成，并运用三次指数平滑法建立了销售额预测模型。预测分析表明，新的营销网络体系较为适应市场需求的变化趋势。     

基于单片机的激光智能小车设计

传统的智能小车采用红外传感器进行路径探测,但由于发射功率较小、受温度影响大、易受红外线干扰,导致系统的前瞻性差、不稳定、鲁棒性差。为了提高智能小车的前瞻性和抗干扰能力,基于单片机设计了一款激光智能小车,该设计采用STC89C52单片机作为小车的核心控制模块,激光传感器作为路径识别模块,霍尔元件A44E作为小车速度检测模块,LCDl602作为液晶显示模块。实践表明,小车可实现2．5m/s匀速前行,具有较高的稳定性和准确性。