配换挂轮齿数的计算方法

齿轮加工时 ,选择配换挂轮是一项重要而烦琐的工作 ,本文介绍配换挂轮齿数的几种简便方法 ,供生产中参考使用     

Long term and safe relative orbit design for heterogeneous spacecraft clusters

The problem of obtaining long term relative orbit configurations for spacecraft clusters with realistic operational considerations such as safety, station keeping and inter-spacecraft distances is addressed. Two different approaches are developed for station keeping and safety objectives. In the first approach, relative orbit configurations, or relative TLEs, are found minimizing deviations from reference mean orbit which would maximize the station-keeping objective. In second one, relative configurations are found from a reference initial condition by minimizing probability of collision, hence maximizing the safety objective, between the spacecraft in the cluster which are propagated numerically through a high precision orbit propagator. For the design optimization, a derivative free algorithm is proposed. Effectiveness of the approaches is demonstrated through simulations. Using this design framework, several configurations can be found by exploring the limits of the clusters in terms of spacecraft number, distance bounds and probabilities of collision for long time intervals.     

利用Cluster资料对经验及抛物面磁场模式性能的研究

Cluster的观测区包括太阳风与磁层相互作用的关键区域.本文将Tsyganenko经验模式T96,T01及Alexeev抛物面模式A2000的模拟结果与Cluster的磁场资料进行了详细对比,研究了两种模式对于近地点分别位于日侧及夜侧磁层的不同Cluster轨道上磁场的模拟性能.结果表明: (1)Cluster近地点附近轨道上的磁场主要受Birkland电流影响,T96,T01能很好地估计电流系位置,但对其强度模拟有所偏差,由于A2000不包含Ⅱ区场向电流,因此模拟不出近地点附近的磁场扰动; (2)对于0＞Dst＞-100 nT情况,T96与T01性能相当,但由于缺少部分环电流,T96对于日侧昏线附近的磁场模拟偏差大; (3)T96与T01对夜侧近地点轨道上磁场模拟的均方根相对误差为40%左右,受极尖区电流影响,日侧时误差上升到50%,而A2000均方根相对误差明显偏大,均为58%左右.      

Possibility to detect the cluster emission up to R200 with XMM-Newton data

We present the results of analysis XMM-Newton data of galaxy cluster CL0016+16, which enables us to trace X-ray emission and temperature profile up to the virial radius. We obtained similar results using three different backgrounds. We checked the possibility of detection of cluster emission up to the virial radius with XMM-Newton data with hydrodynamical cosmology simulation from the Adaptive Mesh Refinement technique, code RAMSES by Teyssier [Teyssier, R. Cosmological hydrodynamics with adaptive mesh refinement. A new high resolution code called RAMSES. A&A 385, 337, 2002], convolution with XMM-Newton and the data base of the spectra by Sauvageot et al. [Sauvageot, J.-L., Belsole, E., Pratt, G.W. The late merging phase of a galaxy cluster: XMM EPIC observations of A 3266. A&A, 444, 673, 2005]. For the first time we were able to compute the mass of CL0016 up to R₂₀₀, we found, assuming hydrostatic equilibrium framework, M₂₀₀ = (1.15 ± 0.11) × 10¹⁵M_⊙.     

Determination of reconnected flux via remote sensing

Magnetic reconnection is one of the most fundamental processes in the magnetosphere. We present here a simple method to determine the essential parameters of reconnection such as reconnected flux and location of the reconnection site out of single spacecraft data via remote sensing. On the basis of a time-dependent reconnection model, the dependence of the reconnected flux on the magnetic field z-component B_z is shown. The integral of B_z over time is proportional to the reconnected flux and depends on the distance between the reconnection site and the actual position where B_z is measured. This distance can be estimated from analysis of magnetic field B_z data. We apply our method to Cluster measurements in the Earth’s magnetotail.     

计算机集群技术在测控系统中的应用研究

本文介绍了计算机集群技术的特点，结合测控系统的应用现状及需求，着重针对数据处理、通信接口和存储系统三个方面，提出了将集群技术应用于测控计算机系统的解决方案。     

Optimization and verification of wind tunnel free-flight similarity law for separation of cluster munition

In view of the separation form of the separator from the back of the carrier upward and from the side of the carrier outward, separation-safety research is carried out by taking the separation of a cluster munition as an example. In previous wind tunnel free-flight tests, the similarity law of vertical, downward, moving submunition was used to design submunitions at different positions in different initial-velocity directions, which resulted in large discrepancies between wind tunnel test results and real flight. In a wind tunnel test, each submunition has an independent time-reduction ratio with respect to the dispenser. Even if the separation trajectory of a single submunition is accurate, there will be errors in the position of each submunition at a given time. Therefore, it is necessary to determine the time-reduction ratio between submunitions, and to modify the test results later. In order to ensure the accuracy of wind tunnel test results, the similarity law of a free-flight test in a wind tunnel is derived in this paper. The time-correction scheme to ensure motion similarity between submunitions is solved. Numerical simulation is used to simulate the separation of a wind tunnel test and real aircraft, and the motion parameters of different submunitions are solved. The results show that the new similarity laws derived for different types of submunitions can greatly reduce the errors caused by previous similarity laws. In addition to the case for the separation of a cluster munition, the similarity law can also be applied to the free-flight test design of wind tunnels for vertical separation and horizontal separation of other kinds of aircraft.     

基于模糊聚类原理确定光测数据处理最优基线的方法

应用模糊数学理论,提出了光测数据处理最优基线的确定方法,有效地解决了长期以来基线选择过程中难以建立数学模型的问题,通过仿真试验验证了该方法的正确性、合理性。     

飞行器集群协同定位与导航对抗技术发展与展望

以动平台飞行器集群为对象,剖析集群协同定位与导航对抗技术内涵,分析技术现状,提炼技术难点,展望技术发展趋势,为未来中国飞行器集群自主时空基准体系构建及导航对抗提供新思路.     

Cluster observations of earthward propagating plasmoid and flux ropes in the near-tail during the course of a substorm event

We analyze the magnetic structures in the near-tail at Xgsm = −17.5 Re on September 19, 2003 by Cluster. During the course of a substorm event, the earthward propagating plasmoid and flux ropes in the near-tail are observed. The earthward propagating plasmoid is associated with the bipolar Bz and By signatures. The two flux ropes are embedded within the earthward plasma flows, which might be referred to the population as ‘‘BBF-type’’ flux ropes. The first flux rope diameter is about 0.7 Re and duration based upon the Bz signature is ∼20 s, while the second one diameter is about 1.4 Re and duration is ∼30 s. The earthward propagating plasmoid and flux ropes could have influence upon the dipolarization and injection in inner magnetosphere. The Cluster observations of earthward propagating plasmoid and flux ropes can be interpreted as strong evidence for multiple X-lines. Our observations are consistent with that multiple plasmoids or flux ropes are formed repeatedly and ejected tailward in the course of geomagnetically active time.