飞轮微振动的组合隔振装置设计及实验研究

针对光学遥感卫星飞轮微振动引起的成像质量下降问题，设计了一种组合隔振装置，并采用仿真分析与实验测试相结合的方法对隔振方案设计的合理性进行验证。首先，将测量的飞轮扰振数据引入光学卫星的有限元模型中，计算出飞轮扰振对光学相机的像素偏移影响；其次，设计了组合隔振方案并基于有限元方法对其隔振效果进行验证；最后，搭建了光学成像微振动实验测试平台，对不同转速下飞轮微振动造成的像素偏移影响进行精确测量。实验结果表明，组合隔振装置对300 Hz以上高频段飞轮扰振有较大衰减作用，最大像素偏移降到0.01个像素以下，隔振效率达到80%以上；通过对比可知，实验测试与仿真计算得到的像素偏移结果在低频段一次谐波响应及模态响应表现出较好一致性，但在高频段二者存在一定偏差。     

The Role and Contributions of Energetic Neutral Atom (ENA) Imaging in Magnetospheric Substorm Research

Energetic Neutral Atom (ENA) imaging has contributed substantially to substorm research. This technique has allowed significant advances in areas such as observation and quantification of injected particle drift as a function of energy, observation of dynamics in the tail that are directly related to the effects of imposed (growth phase) and induced (expansion phase) electric fields on the plasma, the prompt extraction of oxygen from the ionosphere during substorms, the relationship between storms and substorms, and the timing of substorm ENA signatures. We present discussion of the advantages and shortcomings of the ENA technique for studying space plasmas. Although the technique is in its infancy, it is yielding results that enrich our understanding of the substorm process and its effects.     

Progress in battery technology since the first CSULB annual batteryconference and prospects for the future

Significant advances in and applications of battery technology are outlined. Factors driving future developments are identified     

The heliolongitudinal distribution of solar flares associated with solar proton events.

We find that the heliolongitudinal distribution of solar flares associated with earth-observed solar proton events is a function of the particle measurement energy. For solar proton events containing fluxes with energies exceeding 1 GeV, we find a Gaussian distribution about the probable root of the Archimedean spiral favorable propagation path leading from the earth to the sun. This distribution is modified as the detection threshold is lowered. For > 100 MeV solar proton events with fluxes > or = 10 protons (cm2-sec-ster)-1 we find the distribution becomes wider with a secondary peak near the solar central meridian. When the threshold is lowered to 10 MeV the distribution further evolves. For > 10 MeV solar proton events having a flux threshold at 10 protons (cm2-sec-ster)-1 the distribution can be considered to be a composite of two Gaussians. One distribution is centered about the probable root of the Archimedean spiral favorable propagation path leading from the earth to the sun, and the other is centered about the solar central meridian. For large flux solar proton events, those with flux threshold of 1000 (cm2-sec-ster)-1 at energies > 10 MeV, we find the distribution is rather flat for about 40 degrees either side of central meridian.     

AFIT neural network research

A brief summary of research done at the Air Force Institute of Technology (AFIT) in the area of neural networks is provided. It has been shown that backpropagation, used for feedforward artificial neural networks, is just a degenerate version of an extended Kalman filter, and that networks can do about as well as the optimum statistical classification technique. A method of finding the importance of features for use by a neural network classifier has been determined. Techniques for using neural networks for image segmentation have been developed. In optical pattern recognition, techniques that allow the processing of real FLIR (forward-looking infrared) images with existing binary spatial light modulators have been devised. An optical direction of arrival detector applicable to laser illumination direction determination has been designed and tested; the design is similar to a fly's eye. Coated mirrors for the optical confocal Fabry-Perot interferometer have been designed, specified, fabricated, and installed. Significant progress has been made in the use of neural networks for processing multiple-feature sets for speech recognition     

A wavelet multiresolution analysis for spatio-temporal signals

The wavelet filters of the conventional 3D multiresolution analysis possess homogeneous spatial and temporal frequency characteristics which limits one's ability to match filter frequency characteristics to signal frequency behavior. Also, the conventional 3D multiresolution analysis employs an oct-tree decomposition structure which restricts the analysis of signal details to identical resolutions in space and time. This paper presents a 3D wavelet multiresolution analysis constructed from nonhomogeneous spatial and temporal filters, and an orthogonal sub-band coding scheme that decouples the spatial and temporal decomposition processes     

涡旋真空泵的密封设计

涡旋真空泵在工作过程中动、静涡盘之间间隙存在泄漏损失,它是影响涡旋真空泵工作性能的重要因素;总结了涡旋真空泵的工作原理;介绍了涡旋真空泵的密封设计与选择、间隙的确定。从材料和结构两方面阐述了密封的几种结构形式,说明了各自的工作原理,及需要注意的问题,阐明这些问题是影响泵性能指标的重要因素。     

专科英语、本科英语及成人专科英语的定位和相互关系

专科英语在理论上被界定为专门用途英语(ESP)分支下,介于学术英语(EAP)与职业英语(EOP)之间的业务用途英语(EPP)。而本科(大学)英语在理论体系上属于普通英语(GE)。本文从ESP理论的角度探讨了专科英语,本科英语及成人专科英语的定位和相互关系。     

Spiral evolution applied to legacy avionics systems

The US Department of Defense (DoD), through the Office of the Secretary of Defense (OSD), has determined that evolutionary acquisition is their strategy of choice for future software-intensive systems, and that the spiral development model (SDM) is the preferred method/process for software-intensive development life cycles. Electronic Systems Command (ESC) at Hanscom AFB, Massachusetts, has written a draft handbook on the use of Spiral Development for all future Command and Control (C2) systems, including reference to the DoD 5000 series and Air Force Program Directive 63-1, Acquisition System, which deploys this OSD mandate for future C2 systems. Barry Boehm's continued work on SDM which he conceived in the 1980s, is heavily biased toward development of new systems that are software-intensive, as noted in a workshop he gave at the Software Engineering Institute (SEI) in 2000.     

Automotive-grade MEMS sensors used for general aviation

The attitude heading reference system (AHRS) provides data for primary flight instruments, head-up displays, autopilots, and moving map navigation systems. Advances in solid-state MEMS rate sensors, coupled with Kalman filter algorithms designed to mitigate high drift rates, provide the basis for low-cost, high-performance AHRS for general aviation. This paper describes the performance of a low cost, miniaturized AHRS using automotive-grade MEMS sensors. The performance of the system is detailed. The implications for certification of this class of system and fault tolerance are discussed.