Digital and Analog Subcomplementary Sequences for Pulse Compression

Golay's complementary pairing has been a method to increase the utility of binary sequences, because of the temporal sidelobe suppression in the autocorrelation vector summation. Complementary sets of Tseng and Liu and of Hollis exhibit the same effect when several autocorrelations are combined. These complementary pairs and sets of sequences can be extended into long complementary chains by a simple transformation. This transformation is extended here to all pulse compression waveforms. By this method, even though analog complementary sequences cannot be formed, a new class of waveforms, called subcomplementary waveforms, can be formed. Following these rules, repetition of waveforms such as linear frequency modulation (LFM) or linear stepped frequency modulation (LSFM) in a prescribed manner is possible without creating autocorrelation grating lobes or repetitive sidelobes. This method is equally applicable to all analog or digital pulse compression waveforms.     

航空发动机材料标准分析

介绍我国航空发动机材料标准发展状况,分析标准中存在的问题,提出加强航空发动机材料标准化管理的建议.     

Optical Processing Techniques for Simultaneous Pulse Compression and Beam Sharpening

A technique is described in which the separate techniques of beam sharpening (by synthetic antenna methods) and pulse compression are converted into a single two-dimensional operation, which is carried out with a coherent optical processor.     

SVSS: Intelligent video surveillance system for aircraft

Safety and security are the most discussed topics in the aviation field. The latest security initiatives in the field of aviation propose [1I] the aircraft carriers to implement video surveillance within the aircraft at strategic locations. The current proposals allow the video surveillance data to be stored within the aircraft and monitored by one of the flight crew. The monitoring crew will be responsible for identifying the anomaly within the aircraft and take necessary preventive actions. With the introduction of additional technology within the aircraft, mere human perception may not be sufficient to make a decision. In this research work, the authors explore the possibility of implementing a smart video surveillance system (SVSS) within the aircraft that is tuned toward detecting the behavioral anomaly within the aircraft. The SVSS will generate security triggers when it detects an anomaly within the aircraft. These triggers could be combined with other triggers generated by different aircraft components (possible alarms from the flight crew, data traffic anomaly, or alarm generated by one of the avionics components) to provide a better understanding of the situation to the monitoring crew.     

无人机载SAR图像压缩传输中的关键技术研究

本文在深入研究EBCOT算法的基础上.对算法进行了部分改进.设计了基于JPEG2000标准的SAR图像压缩算法,并完成了该算法的软件设计工作,并对其压缩性能和容错性能进行了分析.     

Batch Recursive Data Compression Schemes for INS Error Estimation

Application of new data compression schemes to aided inertial navigation systems is presented. The need for data compression is motivated by the fact that the external aiding system generates frequent but inaccurate position measurements, which have to be processed by a processor whose computation capability is limited. Two new data compression techniques are presented and their efficiency is demonstrated through covariance simulation runs as well as computational complexity analysis. These schemes are characterized by their ability to process batches of measurements recursively and efficiently. It is demonstrated that the resulting estimation accuracy is comparable to that produced by a Kalman filter which processes optimally the same amount of data, while the required computational effort is reduced.     

舱门橡胶密封件压缩行为的有限元模拟

基于非线性不可压缩的Mooney-Rivlin本构理论,建立Ω型舱门橡胶密封件的有限元模型.根据上述有限元模型,分析了密封件在对称的平面下压位移荷载和均布线荷载作用下的变形和应力分布规律.最后,模拟了方向非对称和位置非对称载荷作用下密封件的受力与变形情况,得出了非对称因素对密封件受力的影响规律,并确定了纤维织物对密封件力学性能的影响.     

A Data Compression Technique for Synthetic Aperture Radar Images

A data compression technique is developed for synthetic aperture radar (SAR) imagery. The technique is based on an SAR image model and is designed to preserve the local statistics in the image by an adaptive variable rate modification of block truncation coding (BTC). A data rate of approximately 1.6 bit/pixel is achieved with the technique while maintaining the image quality and cultural (pointlike) targets. The algorithm requires no large data storage and is computationally simple.     

Digital data over video channels: Techniques for Spacelab

Various techniques for transmitting digital data over a composite video channel are examined, with a view to transmitting data from experiments on the Space Shuttle orbiter. PSK (phase-shift keying), MPSK (m-ary PSK), or PAM (pulse-amplitude modulation), which can be transmitted on visible lines of a frame, unassigned lines of the VBI (vertical blanking interval), or during the HBI (horizontal blanking interval), are all found to be attractive under the proper conditions. However, PAM on visible lines or during the VBI should be relatively easy to implement, provide adequate average data rates, and give acceptable BERs (bit error rates)     

A set of systems for labor standards computer-aided design

A set of systems for labor standard computer-aided design is described, namely, initial developments, advance and state-of-the art.     

A methodology for evaluating, comparing, and selecting softwaresafety and reliability standards

The regulated industries, which in the FDA's (US Food and Drug Administration) case include the manufacturers of food, cosmetics, pharmaceuticals, and medical devices, are responsible for selecting and justifying the selection and use of appropriate national and/or international consensus standards. This paper documents the results of a scientific inquiry which was undertaken to develop a methodology to evaluate and select individual standards as well as compatible sets of standards. Initially the scope was limited to software safety and reliability standards. Since then it has been expanded to other areas. It was found that six categories of criteria are important when evaluating the potential use of software safety standards: General Factors, Product Characterization, Process Characterization, Personnel Characterization, Risk Management, and Overall Standards Framework. The criteria in each of the six categories must be addressed, How they are addressed is both a technical and a policy decision. The goal should not be to try to find the “ultimate” standard because there isn't any. Rather the goal should be to select a balanced “diet” of standards based on these six categories. The methodology provides a systematic framework from which to make an objective determination about the appropriateness of using a particular standard     

运动图象的数字压缩技术及其在军事装备中的应用

运动图象具有信息量大、动态感强、真实直观等特点,然而在实际应用中却存在数据量大,处理时间要求高等问题,所以研制压缩比大,实现方法灵活的数字图象压缩算法成为了近几年来信息处理的一个非常活跃的研究热点。本文主要介绍了运动图象的数字压缩的原理和方法,对高效压缩算法MPEG-4中所用到的关键技术进行了详细的讨论,最后结合工程实践简述了数字图象压缩技术在我军装备中的应用情况。     

电刷架精密塑压模的研制

针对电刷架零件的使用功能,在对压塑、挤塑两种成形方法进行比较的基础上,确定了压塑成形。在压塑模上设计了弹片镶块和安装附件,并在出模时与塑件同步顶出等工艺方法,成功试制出了合格零件。     

MIL-STD-1553B总线数据压缩研究

MIL-STD-1553B总线具有实时性、确定性和高可靠性,广泛应用于航空、航天、舰船、坦克等安全、任务关键平台,但其传输率已不能满足日益增长的高传输率需求。针对实际1553B总线系统中存在的大量零元素和数据传输前后变化比例较小的情况,提出了基于软件的数据压缩编码以有效提高实际的数据传输率。分析了零跟踪编码、众数跟踪编码、游程编码、改进型游程编码和差分编码的设计方法,并给出了在现有1553B总线上消息传输中的压缩编码应用。     

Data Compression Techniques for a Sounding Rocket PCM Telemetry System

The standard pulse-code modulation (PCM) telemetry system for a Skylark sounding rocket provided insufficient bandwidth for the high data rate expected from a new, exceptionally large, X-ray astronomy experiment. Several methods of data compression were used to cope with the erratic variability of the chosen source to maximize the returned information. A computer program simulation was used to optimize the variable parameters included in the electronic design to the expected variability of Cygnus X-1 the target X-ray source. The system performed exactly as intended during the actual flight.     

泡沫铝复合材料动态压缩过程数值模拟

利用MSC.marc有限元软件对泡沫铝复合材料的动态压缩过程进行了有限元数值模拟研究,建立了单胞泡沫铝及其复合材料的数值模拟模型,研究了单纯泡沫铝和泡沫铝环氧树脂复合材料的变形过程及应力-应变的分布规律.     

燃气轮机湿压缩试验与应用研究

介绍了燃气轮机湿压缩技术的作用及在世界范围内的应用情况;根据理论分析,分别进行了小型燃机和压气机湿压缩试验,得到了与理论相符的试验结果。     

静态图像无损/近无损压缩技术研究

针对航空侦察图像的原始分辨率高,且在存储过程中必须进行无损或者近无损图像压缩的问题,为满足任务判读的要求,实现实时高效的数据压缩处理具有重要的工程价值。本文首先比较了几种无损或者近无损图像压缩的硬件平台,然后介绍了JPEG标准族的无损/近无损图像压缩的算法框架和不足,最后阐述了最近刚正式问世的新一代JPEG XR图像压缩标准,并指出了JPEG XR标准的优势所在。     

原位合成TiB2/6351复合材料热压缩变形特性

采用Gleeble-1500D热模拟试验机对原位合成TiB2(质量分数,8%)/6351复合材料在不同变形温度和不同应变速率条件下的热变形特性进行了研究,利用透射电镜(TEM)和光学显微镜分析了压缩后试样的微观组织.结果表明, 材料的流变应力随变形温度的升高而降低,随应变速率的提高而增大;材料的流变行为主要表现为加工硬化、动态回复和动态再结晶;相应的显微组织特征为:位错网络、混乱的位错团和胞状结构,亚晶及等轴晶.在应变速率和变形温度均较低时,增强体颗粒周围的基体中形成高密度位错区,但随变形温度的升高而减少;在应变速率较高时,增强体颗粒和基体的界面处开裂甚至增强体颗粒本身发生破碎.