机床主轴支承对主轴系统静、动态特性的影响

本文研究了机床主轴滚动支承的某些重要因素,如前轴承类型、轴承预加负荷、支承数目、主轴二支承结构的支承跨距、主轴三支承结构的紧支承位置及支承跨距等对主轴系统静态和动态特性的影响。     

一个独特的含煤矿区──斗笠山矿区系两个沉积体系的复合体

作者根据斗笠山矿区的沉积相、沉积相序和沉积特征将矿区划分为两种沉积类型，且从两个区的沉积特征分析聚煤规律的差异，对矿区煤层赋存做出预测。图６，表１，参３。     

大别山区地形对春季冷锋附近中尺度对流系统影响的数值模拟研究

安徽省地处亚热带气候和温带气候的过渡带,从副热带高压边缘和孟加拉湾汇合而来的西南暖湿空气与北方南下的干冷空气经常在江准流域相遇,带来丰沛降水.其中,当大别山受暖湿西南气流影响时,其北部易触发对流,出现中小尺度对流系统;当有冷锋等系统影响时,山区北部易出现对流旺盛的中尺度对流系统(MCS).选取2005年3月10日的冷锋过程用天气研究预报模式(WRF)分析研究了大别山地形对冷锋附近MCS发生发展的影响.研究表明:由于大别山地形的作用,山区北部的温度和湿度明显高于平原地区,这一方面产生平原和山区之间的水平气压梯度,形成局地中尺度力管环流,具有触发对流的作用;另一方面,又使山区北部的大气层有大的对流有效位能(CAPE),一旦对流发生,容易剧烈发展.此外,当冷锋移近时,由于大别山的影响,锋后东北风在山区北侧发生堆积和偏转,形成了额外水平风场辐合,使MCS更易形成和维持.     

Numerical simulation of Meiyu front and the diagnosis of moist vorticity vector

Moist vorticity vector is introduced to study the development and evolution of mesoscale convective vortex (MCV) in the Meiyu front precipitation with the Advanced Regional Predication System (ARPS). In this study, the heavy rainfall is simulated to investigate the genesis, development and dissipation of middle scale convective vortex, which occurred from 0000 UTC 3 July to 1200 UTC 5 July over the Jianghuai River valley. Moist vorticity vector (MVV) has zonal, radial and vertical components in its 3D spatial distribution. The simulation shows that the vertical component of moist vorticity vector well demonstrates the spatial distribution characteristics of middle scale convective vortex, especially in the process of Meiyu front precipitation. Diagnosis upon zonal, radial averaged and mass-integrated quantities of MVV shows that its vertical component and the surface precipitating ratio are in phase with a correlation coefficient of 0.68, indicating that the vertical component of MVV is closely associated with the Meiyu front precipitation. In addition, the tendency of the vertical component of MVV is mainly determined by the interaction between the vorticity and the zonal and radial gradient of condensational or depositional heating.     

华池油田三角洲前缘砂体展布的三维建模

目的利用三维建模方法预测三角洲前缘砂体有利储层的分布。方法利用序贯指示模拟法(SIS)对华池油田长3层段三角洲前缘水下分流河道及河口坝微相的砂岩岩相及砂体展布进行随机模拟。结果砂岩岩相模拟的三维实现表明,长31、长32、长33小层中以长33小层砂岩最为发育;砂体展布的三维模拟结果表明,长33小层砂体厚度最大,主砂体主要为东北—西南向展布的条带,主砂体向前伸展并演化为三条次级砂带。砂岩岩相与砂体的三维模拟结果在该区勘探实践中得到了较好的验证。结论在主砂体上砂岩厚度大、物性好,常常发育优质储层。     

机载导弹阵地装备前置最优化模型研究

战机的机动战斗转场要求机载导弹阵地装备进行跟随保障，而过多装备运输量不但耗费巨大的运输费用，而且导致保障的滞后，装备前置研究就是为了解决上述问题，以投资回报率作为装备前置模型目标，提出相关因素分析方法，并应用该方法将谊模型分解成一些相关因素子模型。综合得到的装备前置模型是一个线性约束的非线性最优化模型。最后，将该模型应用到某机载导弹阵地，采用序列二次规划法进行了求解，得出了装备前置结构。     

优化集成系统平台的建立及其应用研究

通过隐式参数化软件SFE CONCEPT进行参数化建模,利用多学科设计优化软件iSIGHT集成SFE CONCEPT、求解器LS-DYNA和数据处理器Matlab,建立优化集成系统平台,以实现产品开发过程优化的快速、自动化.以新开发车型前保险杠横梁为例,在保证碰撞安全性的前提下针对保险杠横梁的轻量化问题,对横梁空间形状、截面高度、宽度以及厚度进行优化.以质量最小为优化目标,碰撞压缩量与车体加速度峰值为约束条件,采用最优拉丁超立方试验设计和模拟退火算法,通过优化集成系统平台对模型进行40%偏置、刚性墙、刚性柱三类低速碰撞仿真分析,得到了满意的效果.     

分离路面上车辆紧急制动时稳定性分析与控制

传统的制动防抱死系统在分离路面上紧急制动时制动效能不尽理想,四通道ABS能够产生最大的制动力但却容易跑偏,而侧向稳定性较好的三通道ABS将增加制动距离.针对这种情况,提出了采用基于四通道ABS的主动前轮转向控制系统,该方法将在最大限度地提高车辆纵向制动力的同时保持车辆的侧向稳定性.建立了一个基于虚拟样机的全功能多体动力学模型,采用联合仿真的方法对车辆在分离路面上高速紧急制动过程进行了动力学仿真.仿真结果表明,提出的控制策略能够提高车辆在分离路面上紧急制动时的侧向稳定性.     

A 600-year flood history in the Yangtze River drainage: Comparison between a subaqueous delta and historical records

Based on grain size analysis and high-resolution elemental scanning of core YD0901, taken from the subaqueous Yangtze River delta, a 600-year flood history was reconstructed for the Yangtze River drainage system. Zr/Rb ratios were chosen as a proxy for Yangtze River floods. Zr resides mainly in the coarse-grained minerals, and Rb is found in the fine-grained minerals. When floods occur, the discharge of the Yangtze River increases, which carries more coarse-grained minerals into the East China Sea. Therefore, deposition of coarse-grained minerals significantly increases relative to fine-grained minerals on the subaqueous delta, and subsequently the Zr/Rb ratios also increase. The higher the Zr/Rb peaks, the greater number of coarse particles deposited by saltation processes. Zr/Rb peaks correlate very well with historical records for Yangtze River floods. Especially at about AD 1870, the Zr/Rb ratio reached a maximum value over the last 600 years, which is consistent with "the extreme flood event" in the upper and middle reaches of the Yangtze River in AD 1870, as indicated in the historical records. Results show that floods have occurred at a relatively high frequency over the last 600 years, which is consistent with historical records when, during the Ming-Qing Dynasty, floods occurred once every 4 years. In addition, spectral analysis of the Zr/Rb ratio showed that there is close link between the Yangtze River floods and ENSO intensity.     

基于dSPACE的汽车主动前轮转向试验台设计

以宝马和采埃孚联合开发的主动前轮转向系统为原型,基于dSPACE实时仿真系统,设计并搭建了主动前轮转向系统的硬件在环实时仿真试验台,给出了试验台的系统架构图,重点分析了试验台的实时仿真过程、主动转向控制方案、变传动比执行电机以及双行星齿轮机构的工作过程。基于此试验台,通过可变传动比、双移线等试验项目验证了主动前轮转向系统的可变传动比、横向稳定控制等功能,为主动前轮转向系统的开发和相关控制器的设计提供了支持。