800 MN大型模锻液压机液压驱动和控制系统的技术研究

详细介绍了800 MN大型模锻液压机液压驱动和控制系统的技术方案、同步控制功能、技术配置指标和技术创新点。     

On energy‐efficient aggregation routing and scheduling in IEEE 802.15.4‐based wireless sensor networks

In wireless sensor networks, continued operation of battery‐powered devices plays a crucial role particularly in remote deployment. The lifetime of a wireless sensor is primarily dependent upon battery capacity and energy efficiency. In this paper, reduction of the energy consumption of heterogeneous devices with different power and range characteristics is introduced in the context of duty scheduling, dynamic adjustment of transmission ranges, and the effects of IEEE 802.15.4‐based data aggregation routing. Energy consumption in cluster‐based networks is modeled as a mixed‐integer linear and nonlinear programming problem, an NP‐hard problem. The objective function provides a basis by which total energy consumption is reduced. Heuristics are proposed for cluster construction (Average Energy Consumption and the Maximum Number of Source Nodes) and data aggregation routing (Cluster‐based Data Aggregation Routing) such that total energy consumption is minimized. The simulation results demonstrate the effectiveness of balancing cluster size with dynamic transmission range. The heuristics outperform other modified existing algorithms by an average of 15.65% for cluster head assignment, by an average of 22.1% for duty cycle scheduling, and by up to 18.6% for data aggregation routing heuristics. A comparison of dynamic and fixed transmission ranges for IEEE 802.15.4‐based wireless sensor networks is also provided. Copyright © 2012 John Wiley & Sons, Ltd.     

重载大跨距横梁弯曲变形分析与补偿

针对重载大跨距横梁的弯曲变形问题,将有限元数值计算和BP神经网络相结合,提出横梁弯曲变形预测方法,通过预制补偿曲线辅助进行横梁弯曲补偿,提高横梁几何精度。首先,利用ANSYS分析软件获得溜板位于横梁一系列工作位置的变形量,作为神经网络的训练样本;其次,通过在Matlab中编程调整网络参数,建立了满足误差要求的BP神经网络模型,并进行训练,利用训练后的神经网络预测横梁变形曲形;最后,对预制补偿曲线的横梁进行弯曲变形测量,实验表明神经网络预测值与实验数据较吻合,相对误差<15%,并且运行时间只需0.27 s。研究结果表明,该方法能够较为准确地预测横梁弯曲变形并进行补偿,为重载大跨距横梁结构设计与预制补偿曲线提供了新的思路和技术支持。     

风廓线雷达在一次大到暴雪天气过程中的应用

利用芜湖市边界层风廓线雷达资料对2012-12-29芜湖市出现的1次大到暴雪天气过程进行分析,结果表明:风廓线的大气风场显示这场大雪属于典型的安徽大雪天气形势。降雪前925hPa左右高度可见东风气流,当东风气流转为西北气流时,降雪天气开始;500~850hPa为西南暖湿气流;降雪时低层冷平流,中高层暖平流,逆温结构有助于降雪的发生;西北气流向上扩展到700hPa高度以上时,降雪趋于结束。雨转雪时,垂直风速由4~7m/s迅速减小到1.4~1.9m/s,表明了雨雪性质的转换,产生的原因是雪的下降速度小于水滴。当垂直风速出现了0值和弱负值,说明大气层结恢复静力平衡,降雪趋于结束。此外,折射率结构常数的变化也同样与降雪过程相对应。     

大型重载推力轴承热弹流计算及尺寸效应

针对考虑热弹变形的大型重载推力轴承性能预测和尺寸效应问题,对某大型重载推力轴承进行热弹流计算,研究轴承性能随极端载荷与尺寸的变化规律。介绍可倾瓦推力轴承热弹流模型的基本方程,通过计算得到不同尺寸和比压下的轴承性能数据,讨论大型重载轴承的尺寸效应。结果表明:案例轴承瓦块最高油膜压力应远离瓦尖,靠近瓦块支点,该设计有利于压力分布均匀而提高承载力;对于大尺寸推力轴承,由于变形的影响,当载荷超过某一限制值后,轴承性能会随着载荷的稍微增加而发生剧烈变化,甚至导致烧瓦失效。为了避免该现象出现,推力轴承设计时应该进行最大许用比压校核;对于大型重载,还需进行瓦块弹性支撑或平衡梁等均载结构设计。     

曲轴不平衡量多面校正的优化分解算法研究

针对生产实际中曲轴动平衡效率低的问题,以最少去重面、总去重量最小为目标,提出一种应用于全自动曲轴动平衡量分解的优化算法——多面校正法。首先对曲轴不平衡量进行测量分解,然后根据分解结果,自动选择去重面,进行去重。多面校正法成功减少了曲轴总去重量,实现了平衡去重的优化。另外,该算法可根据实际曲轴结构的不同,选择与之对应的去重块和扇面角度,显著扩大了测试系统的适用范围。应用此算法对曲轴不平衡量进行优化分解,能够有效提高曲轴生产效率和产品合格率,降低曲轴制造成本。     

铝合金薄壁中空结构件重负荷铣削刀具寿命及刀具磨损研究

使用高速钢和硬质合金刀具,在机床转速n=2000-5000r/min、进给速度vf=1000mm/min、轴向切深ap=20mm、径向切宽aw=10-20mm的切削用量范围内对铝合金薄壁中空结构件重负荷铣削加工刀具寿命及刀具磨损进行研究。结果表明:M42高速钢刀具由于刀具磨损率高、刀具破损和粘结严重而不适合该结构件的重负荷铣削;非波刃粉末冶金高速钢和硬质合金刀具具有良好的适应性,但无刀尖圆弧半径的高速钢刀具易发生刀尖破损,涂层硬质合金刀具易发生涂层过早剥落;波刃粉末冶金高速钢刀具易于发生刀具严重粘结,只宜在较低的机床转速下进行重负荷铣削加工;机床转速和径向切宽对刀具寿命有显著影响。     

Stabilizing Mechanism and Running Behavior of Couplers on Heavy Haul Trains

Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train forces generated by longitudinal in-train forces and coupler rotations have become a more and more significant safety issue for heavy haul train operations. Derailments caused by excessive lateral in-train forces are frequently reported. This article studies two typical coupler systems used on heavy haul locomotives. Their structures and stabilizing mechanism are analyzed before the corresponding models are developed. Coupler systems models are featured by two distinct stabilizing mechanism models and draft gear models with hysteresis considered. A model set which consists of four locomotives and three coupler systems is developed to study the rotational behavior of different coupler systems and their implications for locomotive dynamics. Simulated results indicate that when the locomotives are equipped with the type B coupler system, locomotives can meet the dynamics standard on tangent tracks; while the dynamics performance on curved tracks is very poor. The maximum longitudinal in-train force for locomotives equipped with the type B coupler system is 2000 kN. Simulations revealed a distinct trend for the type A coupler system. Locomotive dynamics are poorer for the type A case when locomotives are running on tangent tracks, while the dynamics are better for the type A case when locomotives are running on curved tracks. Theoretical studies and simulations carried out in this article suggest that a combination of the two types of stabilizing mechanism can result in a good design which can significantly decrease the relevant derailments.     

重油催化裂化催化剂LDC-200的性能评价及工业应用

利用中型提升管催化裂化装置对重油催化裂化（RFCC）催化剂LDC-200的性能进行了评价,并介绍了其在300万t/a RFCC工业装置的应用情况.工业应用结果表明,在原料油性质和主要操作参数基本稳定的情况下,与参比催化剂LDO-70相比,汽油、柴油收率分别增加0.29,0.54个百分点,油浆收率下降0.71个百分点,焦炭及损失降低1.03个百分点;总液体收率增加1.77个百分点,轻质油收率增加0.83个百分点,丙烯选择性增加1.72个百分点;汽油烯烃体积分数增加4.9个百分点,辛烷值（RON）增加1.5个单位.     

关于济阳坳陷浅层气藏与稠油油藏联合勘探的思考

济阳坳陷历经50多年的勘探开发,发现了众多的浅层气藏和稠油油藏,明确二者的分布及成因关系对下步勘探具有指导意义。通过对浅层气藏与稠油油藏的空间分布和地球化学特征进行研究,发现二者在空间分布上存在伴生现象,即在稠油油藏的上方或上倾方向常发育浅层气藏,而在浅层气藏的下伏或下倾方向往往发育稠油油藏;在成因上具有共生关系,浅层气藏主要为油溶释放气和原油降解气,而油藏中的油气由于生物降解及天然气脱出等原因形成稠油。根据研究成果提出了浅层气藏与稠油油藏联合勘探的设想,即由已知浅层气藏寻找未知稠油油藏,由已知稠油油藏寻找未知浅层气藏,或者根据地震亮点寻找浅层气藏,进而寻找稠油油藏。