一种新型大抽速真空粗抽系统设计

文章介绍了一种大抽速真空粗抽系统的设计方法。这种系统是利用国内已研制出的新型直排大气罗茨泵而进行设计的,它可以大大缩短真空容器的粗抽时间。     

月球探测器直接软着陆最优轨道设计

研究月球探测器直接软着陆最优轨道的设计问题。首先根据探测器直接软着陆的特点，提出了有限推力最省燃料的最优轨道设计问题；然后利用有限推力月面软着陆的最优推力控制方向的计算公式，研究了边值条件和计算方法；最后通过直接软着陆最优轨道的算例及结果分析，发现开始制动高度越低越省能量；推力方向可变时比不可变时节省能量；推力大小可变相当于采用了多级制动，对安全定点着陆非常有利。     

直接力控制在垂直攻击型武器上的应用

介绍垂直攻击型武器在末制导段的特点及其对控制系统的特殊要求 ,为此提出三种控制方案 ,并从原理上分析它们各自的优缺点 ,得出直接侧力控制是满足其在末制导段控制要求的最佳方案。同时 ,设计出对应于这三种控制方案的控制律 ,并进行末制导段的仿真验证 ,结果证实了理论分析的结论 ,即直接侧力控制是最佳方案 ,为型号设计提供了具有实际参考价值的结论。     

Direct thrust control for multivariable turbofan engine based on affine linear parameter-varying approach

A novel turbofan Direct Thrust Control(DTC) architecture based on Linear ParameterVarying(LPV) approach for a two-spool turbofan engine thrust control is proposed in this paper.Instead of transforming thrust command to shaft speed command and pressure ratio command, the thrust will be directly controlled by an optimal controller with two control variables. LPV model of the engine is established for the designing of thrust estimator and controller. A robust LPV H∞filter is introduced to estimate ...     

多循环吸气式脉冲爆震发动机推力直接测量

1引言脉冲爆震发动机(Pulse Detonation Engine,简称PDE)是利用间歇式爆震波产生的高温高压燃气来产生推力的新概念发动机。其燃烧过程为非定常过程。整个过程是间歇式的、周期性的,因而产生的推力是脉动的,PDE产生推力的方式和工作特点决定了其测量推力的方法与一般的涡喷发动     

政府主导型私营企业劳资关系研究——基于农民工二重性的视角

农民工二重性的实质是农村和农民贫困的变相表现形式,是由“前市场差异”等制度性和结构性原因造成的。农村和农民的贫困,放大了工资收入对家庭的边际效应,降低了农民工对低工资的敏感度,提高了农民工对超时工作和恶劣劳动条件的忍耐力;当前直接经济收入和未来预期收入的替代效应,为雇主的低工资和低福利状态在农民工心里预留了空间;打工收入和农业收入之间的替代互补效应缓解了农民工与雇主的直接冲突;无长期定居城市的预期降低了农民工参与建立长期稳定和谐劳资关系制度的激励;“勤俭持家”的行为准则使农民工更关注提高自己的生产性努力和减少消费性支出,而不是争取分配性收入的增加;“安分守己”、“自私自利”、“等级观念”等降低了农民工通过正式制度和集体行动维护自己权益的意愿。农民工的二重性从总体上缓解了私营企业劳资关系的浅层矛盾,掩盖了深层矛盾。农民工的二重性是制度性和结构性原因造成的,短期内难以依靠农民工个人和集体的力量获得实质的改善。农民工的二重性为我们建立和谐劳资关系预留了一定的时间和空间,但这种时间和空间是有限的。政府的直接干预,是保证私营企业劳资关系和谐运行的前提条件。建立政府主导型的私营企业劳资关系,在中国有其存在的合理性和必要性。     

Hall推力器羽流数值模拟

以稳态等离子体推力器(SPT)羽流流场为研究对象,基于直接蒙特卡罗模拟与粒子单元混合方法建立数值模型,模拟等离子体稳态流动,研究流场特性。将计算结果与实验数据相比较,并与同类推力器羽流参数进行比较,以保证仿真可靠性。研究表明,所建立的仿真模型能够较好地预测SPT羽流电子数密度和离子电流密度等参数。     

国外高分辨率相机与卫星平台连接方式综述

文章通过对比分析高分辨率相机与卫星平台之间的结构一体化程度,总结出三种不同类型的连接方式,并对它们的受力形式以及传力特点进行了详细的列表对比和分析总结,给出了中国敏捷成像相机与卫星平台一体化设计的建议。     

Characteristics of recent dust storms over the Indian region using real time multi-satellite observations from the direct broadcast receiving system at IMD

In this study, observations from microwave satellites, visible and infrared instruments have been analyzed to detect dust storm over north and north–west part of India during 18–23 March 2012. This study investigated the approach to utilize the multi satellite data of Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the Terra and Aqua satellite and the Advanced Microwave Sounding Unit (AMSU) on-board NOAA satellite to study the characteristics of dust storms from real time direct broadcast (DB) receiving system installed at three places of India Meteorological Department (IMD). The dust storm detection is based on the infrared brightness temperature (BT) difference between channels at 11 and 12 μm and polarized BT difference between two channels of 89 and 23.8 GHz. It is found that the significant differences between the BT of channel 89 and 23.8 can be used as a discriminator of identifying dust storm. The Total Ozone Mapping Spectroradiometer (TOMS) Aerosol Index (AI) and AMSU-A 23 GHz channel BT from NOAA satellite over the north and north-west part of India have also been analyzed. The result indicated the characteristic behavior between BT and AI during the different phases of the dust storm. Finally, the occurrence of dust outbreaks has also been validated with sky radiometer of IMD, which confirms the presence of a dust storm over the Indian region. Further, the findings of the study and its approaches apply to the other dust storm cases which occurred during the months of April and June 2012. The integrated approach suggested the potential to use high resolution data of microwave as well as thermal–infrared using multi-satellite observations from real time direct broadcast system for the detection of severe, moderate or weak dust storms very well. The approach is found to be promising for operational application.     

欧洲市场直接运营成本（DOC）分析方法及应用

根据欧洲民航实际运营情况,总结分析欧洲AEA模型中用于飞机竞争分析和总体参数优化的DOC计算方法,建立欧洲市场直接运营成本计算分析模型,然后就某机型的欧洲市场和中国市场DOC计算进行分析,最后指出未来研究的方向。