汽车前大灯LED光源散热技术

散热问题一直是制约LED在车灯上广泛运用的技术瓶颈。通过分析高温环境对LED的危害、LED的发热机理,基于神龙公司某款车型大灯的LED散热模型,对当前通用的翅片散热法进行探讨。研究结果表明,翅片散热面积、厚度、材料等对翅片散热这种被动散热方式的散热效果影响显著,设计时需综合考虑。而翅片散热作为一种优秀的散热方案,可作为后期开发LED大灯的优先选择方案。     

正交试验法在前翼子板成形数值模拟中的应用

根据正交试验原理,应用板料成形软件PareStamp 2G对不同压边力、模具与板料间摩擦系数、凸凹模间隙和板料初始尺寸进行数值模拟,将数值模拟的厚度同实际成形件的厚度进行比较,得出上述因素对前翼子板成形结果的影响,并预测了前翼子板较优的理论成形条件。     

摩托车前减震器随机激励下的响应分析

对摩托车前减震器进行动态分析,建立动力学方程力学模型,对系统响应路面激励的联合马尔可夫转移密度函数分析并归一化求解,求出了函数的稳态解．通过变量逆变换得到系统的联合概率密度函数．当车速提高时振幅将降低,但振动频率将随着增加,振动强度并不一定减少．增加阻尼系数、减小导向座与减振柱的内径比可以有效缓冲振动．     

精铰挤光复合铰刀在气缸盖加工中的应用

介绍了一种精铰挤光复合铰刀，它可以一次完成三个工序的工作，从而达到提高加工精度，节省劳动时间和操作工人的目的。     

原木板材的窑式干燥

本文综述了canterbury大学近年来关于新西兰木材窑式干燥的研究。有些硬木单纯窑式干燥是困难的,但利用太阳能窑式风干则有可能;轮回操作可以减小干燥应力从而减小产品性能的退化程度。种植生产为主的软木干燥较容易,从经济考虑应采用高温干燥,以减少干燥时间。高温操作时对流传递显得相当重要。实验表明,当空气流过板面时,不同点处的传质系数有显著差异。湿分在木板中移动的模型可假定为:随着干燥进行蒸发面向中心退缩。但心材和边材的行为有所不同:边材中的水份可在相邻脉管间迁移,但在心材中则不可能。正是这种差异导致干燥时间和干燥温度曲线不同。     

精英克隆局部搜索的多目标动态环境经济调度差分进化算法

为有效解决复杂多目标动态环境经济调度问题,提出一种基于精英克隆局部搜索的多目标动态环境经济调度差分进化算法.以传统的差分进化(differential evolution,DE)算法为框架,为了提高DE算法的开采和探索能力,增设精英群的克隆和突变机制,采用动态选择方式确定精英群,有效增强算法的全局搜索能力.数值试验以I...     

Analysis of the scale up of a transpiring wall reactor with a hydrothermal flame as a heat source for the supercritical water oxidation

Experimental data from a tubular reactor and from a transpiring wall reactor (TWR) are used to analyze the scaling up of SCWO reactors operating with a hydrothermal flame as a heat source. Results obtained with the tubular reactor show that fluid velocity inside the reactor determines the minimum injection temperature at which a stable hydrothermal flame is formed. When the fluid velocity inside of the reactor is lower, the extinction temperature of the hydrothermal flame in that reactor is also lower. Using this reactor, extinction temperatures are always near or above the critical temperature of water. Total TOC removals are possible working with isopropyl-alcohol at temperatures between 650 and 700 °C and residence times of 0.5 s. Results of the TWR show that steady operation with a hydrothermal flame inside is possible even when reagents are injected at subcritical conditions as low as 170 °C. Temperature measurements show that reaction is not initiated in the injector but in the reaction chamber, where fluid velocity is lower than 0.1 s. This was explained by estimating that the flame front velocity of a hydrothermal flame is of the order of 0.1 m/s. Thus, it is expected that the flame is stabilized in the reaction chamber and not in the injector, where fluid velocities are higher than 2 m/s. A previously developed model of the TWR was modified in order to describe the ignition in the reaction chamber and not in the injector. The model reproduces satisfactorily experimental data and it was used to propose the design of scaled up reactors for SCWO with a hydrothermal flame inside.     

中国地区海风(锋)的数值模拟研究进展

海风锋是海风环流前缘形成的锋面,具有类似于冷锋的特征.海风锋能触发强对流,造成沿海地区雷暴等灾害性天气,是沿海地区气象研究的重点对象.随着数值模式和计算机技术的发展,数值模拟已成为气象研究中的重要方法.因此,海风(锋)的数值模拟受到越来越多的关注.过去的40年中,中国地区海风(锋)的数值研究不断开展,取得了不少研究成果.为了加深对海风(锋)数值模拟的认识,了解最新研究成果,本文对中国地区海风(锋)数值模拟进行了概述,重点讨论了海风三维结构与演变以及背景风、地形、城市热岛和大气稳定度对海风(锋)的影响.此外,本文也归纳总结了模式物理过程参数化对海风(锋)模拟的影响以及海风(锋)的大涡模拟研究.最后,对一些需要进一步研究的问题提出了建议.     

主动前轮转向和直接横摆力矩集成控制

针对车辆操稳性控制中功能耦合的主动前轮转向（AFS）与直接横摆力矩控制（DYC）的任务协调问题,提出优化相平面法进行稳定区域划分.基于所提方法建立轮胎侧向力特性协调准则,实现纵横向动力学系统操稳性集成控制.以前、后轮侧偏角及两者之差作为车辆横向稳定的表征量,结合轮胎侧向力特性划分车辆横向状态为稳定、临界稳定和失稳状态区间.建立AFS与DYC的协调准则.考虑控制算法面向实际应用时状态量的获取问题,建立基于超螺旋算法的状态观测器估计车辆前后轮侧偏角.分别设计基于自适应超螺旋高阶滑模算法的AFS和DYC控制器,在消除控制器抖振和避免频繁切换的基础上完成稳定性控制.试验结果表明,所提协调准则和控制算法对协调AFS和DYC有积极作用,且操稳性控制效果良好.     

Dynamic behavior of particles across flame propagation through micro-iron dust cloud with thermal radiation effect

In this investigation, a theoretical study is performed to analyze the dynamic behavior of particles across flame propagation through a two-phase mixture consisting of micro-iron particles and air. In the first step for calculation of the particle velocity profile, the Lagrangian approach of particle motion is employed, and then thermophoretic, gravitational and buoyancy forces are taken into consideration. In order to simulate the temperature profile for the thermophoretic force, it is assumed that the flame structure consists of three zones: preheat, reaction, and post flame (burned). It should be noted that the radiative heat-transfer equation is employed to describe the thermal radiation exchanged between the burned zone and the preheat zone. In the resumption, a control volume above the leading edge of the combustion zone is considered and the change in the particle number density in this volume is obtained via the balance of particle mass fluxes passing through it. The results show that the induced thermal radiation plays a significant role in increasing the mixture temperature all over the preheat zone, and that the particle velocity profile and the concentration distribution of particles as a function of distance from the leading edge of the combustion zone also have considerable consistency with published experimental data.