多轴混合动力特种车辆空气动力学特性分析与改进设计

建立某多轴混合动力特种车辆整车外流场仿真模型,采用计算流体力学方法分析整车外流场特性.根据分析结果对驾驶室进气格栅、驾驶室与货箱之间的上部连接、驾驶室下部进风口三个部位进行优化设计.在优化设计过程中,特别关注提升各车桥分布式驱动电机的散热效果,并根据局部外流场特性确定车桥处的电机风扇朝向布置.结果表明,优化后的整车风阻...     

一类带子块约束的矩阵方程的求解

考虑矩阵方程AXB=D在约束条件X([1r∶,1∶s])=X0下的可解性问题,其中X([1∶r,1∶s])表示矩阵X的前r行,前s列组成的子矩阵。给出了此问题有解的充分必要条件,并在有解时给出了通解的显式表示。     

反相悬浮聚合法制备AMPS/AA高吸水树脂

以N,N-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,span60为分散稳定剂,采用反相悬浮聚合法制得2-丙烯酰胺基-2-甲基丙磺酸（AMPS）和丙烯酸（AA）共聚高吸水性树脂．正交实验结果表明最佳合成条件：^nAMPS：^nAA=1.8：1,中和度70％,引发剂0．1％,交联剂0．05％．合成的树脂在室温下吸蒸馏水和0．9％（wt％）NaCl溶液分别为990g/g和123g/g．     

Air transportation in a carbon constrained world: Long-term dynamics of policies and strategies for mitigating the carbon footprint of commercial aviation

With increasing demand for air transportation worldwide and decreasing marginal fuel efficiency improvements, the contribution of aviation to climate change relative to other sectors is projected to increase in the future. As a result, growing public and political pressures are likely to further target air transportation to reduce its greenhouse gas emissions. The key challenges faced by policy makers and air transportation industry stakeholders is to reduce aviation greenhouse gas emissions while sustaining mobility for passengers and time-sensitive cargo as well as meeting future demand for air transportation in developing and emerging countries. This paper examines five generic policies for reducing the emissions of commercial aviation; (1) technological efficiency improvements, (2) operational efficiency improvements, (3) use of alternative fuels, (4) demand shift and (5) carbon pricing (i.e. market-based incentives). In order to evaluate the impacts of these policies on total emissions, air transport mobility, airfares and airline profitability, a system dynamics modeling approach was used. The Global Aviation Industry Dynamics (GAID) model captures the systemic interactions and the delayed feedbacks in the air transportation system and allows scenarios testing through simulations. For this analysis, a set of 34 scenarios with various levels of aggressiveness along the five generic policies were simulated and tested. It was found that no single policy can maintain emissions levels steady while increasing projected demand for air transportation. Simulation results suggest that a combination of the proposed policies does produce results that are close to a “weak” sustainability definition of increasing supply to meet new demand needs while maintaining constant or increasing slightly emissions levels. A combination of policies that includes aggressive levels of technological and operations efficiency improvements, use of biofuels along with moderate levels of carbon pricing and short-haul demand shifts efforts achieves a 140% increase in capacity in 2024 over 2004 while only increasing emissions by 20% over 2004. In addition, airline profitability is moderately impacted (10% reduction) compared to other scenarios where profitability is reduced by over 50% which pose a threat to necessary investments and the implementation of mitigating measures to reduce CO2 emissions. This study has shown that an approach based on a portfolio of mitigating measures and policies spanning across technology and operational improvements, use of biofuels, demand shift and carbon pricing is required to transition the air transportation industry close to an operating point of environmental and mobility sustainability.     

车辆动力学控制的模拟

本文用模拟方法研究了车辆动力学控制系统。采用闭环的横摆角速度及车辆侧偏角控制，用它们之间的相平面分析确定控制策略。这一控制集成了基于滑移率控制的ＡＢＳ系统，实施简单，鲁棒性强，模拟结果显示该系统能有效地改善车辆的动力学性能。     

商用车驾驶室悬置隔振仿真研究

采用多刚体系统动力学理论研究商用车驾驶室悬置隔振系统的平顺性问题，提出了基于多刚体动力学的现代虚拟样机技术进行驾驶室悬置隔振系统设计和计算分析方法，运用ADAMS软件建立了整车系统的参数化振动模型，结合实际参数对典型货车进行了随机振动分析，以驾驶室座椅处加速度均方根值为评价对象对原车驾驶室悬置系统和底盘主悬架系统进行了参数匹配和改进设计，解决了原车隔振效果差的问题。     

钢板弹簧建模方法研究

建立了5种不同的钢板弹簧模型,并从钢板弹簧自身的力学特性、悬架系统的K&C特性以及整车动态特性等方面,对这5种钢板弹簧模型进行了仿真分析对比.结果表明,在传统的SAE三连杆方法和离散梁方法的基础上引入梁单元而提出的扩展三连杆方法,建模过程较简便,仿真结果与公认具有较高精度的离散梁模型的结果较接近,比较适用于悬架子系统和整车分析.     

基于博弈论的空铁联运收益分配模型

理想的空铁联运收益分配方式是实现航空与高铁深度合作的重要条件.本文考虑旅客对空铁联运服务水平和价格的敏感度等影响因素,根据空铁联运的实际运营情况,探究通过收益共享合同协调航空和高铁的利益冲突,形成理想的收益分配方式并促进空铁联运的发展.基于不同的合作水平,使用纳什议价效用函数模拟议价过程,建立航空主导的和具有议价行为的...     

船载登陆栈桥系统卸载时的横摇响应计算

在无码头的情况下,利用集装箱船改装后的渡海输送登陆栈桥系统,具有装卸载不依赖吊装设备的优点,使登陆栈桥系统能够迅速展开和拼装.在缺乏港口屏蔽的海浪环境中,登陆栈桥系统进行卸载,必须考虑波浪对船的作用和登陆栈桥系统与船的相互作用.利用浮基多体系统动力学方法,考虑海况、船型和登陆栈桥系统在船上运动参数等因素,计算了各工况下的横摇运动响应,进而给出了登陆栈桥系统安全卸载的操作要求,对集装箱船改装可行性提供了理论支持.     

Powertrain technologies and their impact on greenhouse gas emissions in key car markets

The role alternative car technologies may play in effectively tackling the problem of climate change is still highly uncertain. This paper aims at investigating possible impacts of car powertrain technologies on future energy demand and its corresponding greenhouse gas emissions until 2030. A system dynamics model covering nine car technologies in China, France, Germany, India, Japan and the United States was applied, with a focus on electric cars. Four main scenarios are constructed and sensitivity analysis undertaken. Greenhouse gas emissions from cars in the six countries are simulated to reach up to 2.6 gigatonnes in 2030 (a 13–32% increase between 2020 and 2030, depending on the scenario). The main conclusion from model-based policy analysis is that electric cars may have a positive contribution to emissions mitigation in the passenger road transport system. However, greenhouse gas emissions from cars arising from the combined effect of car manufacturing and scrappage and electricity generation processes are expected to grow more dramatically. As a result, actions that support both low-emission (re-)manufacturing and clean electricity generation are needed. These results complement accurate but static life cycle assessments and open the discussion for dynamic model assumptions.