FC-AE-1553网络传输性能评价

为了提高航天航空网络传输性能,提出一种通用的FC-AE-1553网络传输效率计算方法并研制高性能FC-AE-1553节点卡.首先,对FC-AE-1553网络的消息传输过程进行详细分析,分析信息类型,给出传输帧的格式建议,通过分析FC-AE-1553协议中各类消息传输的时间参数,结合FC标准中对通信时间的要求,提出FC-AE-1553网络交换中各种消息类型的通信时间计算公式.然后, 针对无差错传输和有差错传输两种情况,给出了网络传输效率的计算方法.最后,通过仿真分析数据帧净荷长度、节点处理时间、交换中序列数量、传输误码率、丢包率等参数对FC-AE-1553网络传输效率的影响,给出了网络优化设计的建议.依托某航天工程任务,研制了基于XC5VFX100T和MPC8536E的FC-AE-1553节点卡.实验结果表明:丢包对传输效率的影响可忽略;数据帧净荷为2 048 B,数据帧数量为16时,传输效率可达到77.2%.      

View-dependent progressive transmission and rendering for lunar model based on bicubic subdivision-surface wavelet

Given the fact that the back of the digital lunar model is invisible from any viewpoint, a view-dependent progressive transmission and rendering method for lunar model is proposed and a client-server browsing system is implemented. On the server side, the semi-regular lunar surface is partitioned into dozens of segments, and each segment is compressed independently using bicubic subdivision-surface wavelet and SPIHT. For any viewpoint, only the data of the visible segments are transmitted to the client side progressively, then decoded and locally reconstructed there. This approach not only improves the efficiency of transmission, but also reduces the reconstruction time greatly. We can browse the lunar model on the client almost in realtime.     

利用等离子体通道实现空间太阳能无线能量传输

空间太阳能电站是高效利用太阳能的有效途径,受到了国际的广泛关注。空间无线能量传输技术是空间太阳能电站的关键技术之一。文章首先分析了微波与激光无线能量传输技术的问题,根据空间太阳能传输的具体需求进一步提出基于等离子体通道的无线能量传输技术,并对基于此项技术的空间太阳能传输系统进行了论证,完善并发展了空间太阳能传输模型。基于等离子体通道的无线能量传输技术为多个领域的能量补给提供了新颖的技术途径,是具有广阔应用前景的战略选择。     

Modeling and Optimal Design of 3 Degrees of Freedom Helmholtz Resonator in Hydraulic System

Three degrees of freedom (3-DOF) Helmholtz resonator which consists of three cylindrical necks and cavities connected in series (neck-cavity-neck-cavity-neck-cavity) is suitable to reduce flow pulsation in hydraulic system. A novel lumped parameter model (LPM) of 3-DOF Helmholtz resonator in hydraulic system is developed which considers the viscous friction loss of hydraulic fluid in the necks. Applying the Newton’s second law of motion to the equivalent mechanical model of the resonator, closed-form expression of transmission loss and resonance frequency is presented. Based on the LPM, an optimal design method which employs rotate vector optimization method (RVOM) is proposed. The purpose of the optimal design is to search the resonator’s unknown parameters so that its resonance frequencies can coincide with the pump-induced flow pulsation harmonics respectively. The optimal design method is realized to design 3-DOF Helmholtz resonator for a certain type of aviation piston pump hydraulic system. The optimization result shows the feasibility of this method, and the simulation under optimum parameters reveals that the LPM can get the same precision as transfer matrix method (TMM).     

基于 GPS 和电子海图的落水人员搜救定位系统

现阶段我国的海上搜救工作仍然采用救生衣方式的被动求救和大面积搜索的模式,搜救效率较低.为了解决了这个问题,本文设计实现了基于全球定位系统(GPS)和电子海图的落水人员搜救定位系统.该系统将 GPS、地理信息系统(GIS)、数据库同步、无线传输技术有机结合,有效保障了落水人员的精确定位,为救援船舶及时追踪落水人员提供了可靠的依据     

我国货币政策的传导机制——基于商业银行视角

货币政策通过信贷渠道的传导离不开贷款服务机构尤其是商业银行。货币政策受中央银行的存款准备金制度影响,从商业银行贷款、存款和金融创新等方面影响居民和企业的消费和投资活动,最终影响实体经济的运行。因此,充分发挥商业银行货币政策传导的主渠道作用,对于取得货币政策实施的最大效应,具有极其重要的作用。     

基于无线激光通信的转子参数遥测方法研究

为了满足航空发动机转子、直升机旋翼等旋转部件动态参数的高速实时采集需求,提出了一种基于无线激光通信的旋转部件非接触参数遥测方法,并给出了基于该方法的参数遥测系统总体方案.重点研究了光电数据传输通道中发射激光器的信号驱动、光电探测器的信号放大及串行/解串器等关键电路的设计方法.设计了理论最大传输速率达622 Mb/s的无线激光通信收发模块,并测试了收发模块的实际性能.最后,研制了参数遥测试验样机,该样机在旋转状态下的数据传输率达300 Mb/s,满足航空发动机转子的动态参数遥测要求.      

月面钻取采样回转齿轮副啮合生热试验研究

针对月面钻取采样装置的回转齿轮副啮合热进行理论分析,依据辐射换热定律建立了理论温升模型;模拟实际月面真空、带载工况并开展试验研究。分析了啮合热在月面高真空环境的制约条件下,向机体外传播的方式、传热途径以及散发不畅时的积聚作用对附近运动副工作特性的影响。研究结果表明：回转齿轮副作为钻具驱动单元动力传递的中间环节,在20Nm负载转矩工况下持续运行40分钟,理论预测最大温升28.66℃,与试验测量的最大温升结果28℃相吻合,充分验证了钻进驱动单元热设计的正确性,准确地识别出回转齿轮副啮合热积聚的潜在风险。     

Relay selection based on MAP estimation for cooperative communication with outdated channel state information

In this paper, we consider an amplify-and-forward (AF) cooperative communication system when the channel state information (CSI) used in relay selection differs from that during data transmission, i.e., the CSI used in relay selection is outdated. The selected relay may not be actually the best for data transmission and the outage performance of the cooperative system will deteriorate. To improve its performance, we propose a relay selection strategy based on maximum a posteriori (MAP) estimation, where relay is selected based on predicted signal-to-noise ratio (SNR). To reduce the computation complexity, we approximate the a posteriori probability density of SNR and obtain a closed-form predicted SNR, and a relay selection strategy based on the approximate MAP estimation (RS-AMAP) is proposed. The simulation results show that this approximation leads to trivial performance loss from the perspective of outage probability. Compared with relay selection strategies given in the literature, the outage probability is reduced largely through RS-AMAP for medium-to-large transmitting powers and medium-to-high channel correlation coefficients.     

Concept of wireless sensor network for future in-situ exploration of lunar ice using wireless impedance sensor

It is known that a wireless sensor network uses some sort of sensors to detect a physical quantity of interest, in general. The wireless sensor network is a potential tool for exploring the difficult-to-access area on the earth and the concept may be extended to space applications in future. Recently, lunar water has been detected by a few lunar missions using remote sensing techniques. The lunar water is expected to be in the form of ice at very low temperatures of permanently dark regions on the moon. To support the remote observations and also to find out potential ice bearing sites on the moon, in-situ measurement of the lunar ice is essential. However, a rover may not be able to reach the permanently shadowed regions due to terrain irregularity. One possibility to access such areas is to use a wireless sensor network on the lunar surface.