小型机载数字视频记录系统的设计与实现

采用嵌入式控制模块SOM2386和专用视频处理芯片SZ1510,设计和实现了一种基于电子硬盘存储的嵌入式小型机载数字视频记录系统。给出了系统总体方案,阐述了视音频解码编码、接口、控制及存储单元的硬件设计,介绍了系统的软件设计,并给出了系统软件的整体工作流程。该系统体积小、重量轻、抗震性好、使用维护方便,已在某型飞机上得到应用。     

N-苄基丙烯酰胺的合成

以丙烯腈和苯甲醇为原料，浓硫酸作催化剂，合成了N-苄基丙烯酰胺（N-BAA）。考察了反应温度、反应时间和催化剂用量等因素对产物收率的影响，得出了最佳反应条件：n（丙烯腈）：n（苯甲醇）：n（浓硫酸）=3：1：1．2，反应时间3h，反应温度60℃。在最佳条件下，N-BAA的收率可达92％。每100g粗产物用10％氢氧化钠溶液提纯，精制产物纯度可达99．80％，熔点为64～65℃。通过红外光谱对产物结构进行了表征。     

Internet中文信息搜索引擎评析

介绍搜索引擎的分类、对比和查询技巧。     

碳纤维缠绕复合材料在潜水外压容器上的应用

在铝合金圆筒体外以浸渍树脂碳纤维进行缠绕复合增强，增强后的筒体耐静水外压能力大幅度提高；整体缠绕的全复合材料筒体，在耐静水外压能力及减轻自身重量方面也获得了明显的效果。此外，在铝合金细长圆管的外壁复合缠绕碳纤维，能有效地提高圆管对轴向压载荷的抗失稳与抗屈曲破坏能力。     

彩色PDP用玻璃基板

本文讨论了彩色ＰＤＰ现用钠钙玻璃的热稳定性，指出由于这种玻璃在热处理过程中易变形和收缩，因而不适合作大面积彩色ＰＤＰ基板材料，介绍了彩色ＰＤＰ基板玻璃的制造方法和特点。最后介绍了日本旭硝子公司和美国康宁公司各自为彩色ＰＤＰ新开发的玻璃基板材料ＰＤ２００和ＣＳ２５。     

Releasing N jobs to an unreliable machine

In this paper we develop an algorithm that determines the optimal times of releasing N jobs to an unreliable machine. The job processing times are assumed to be random and the machine is subject to random breakdowns. The objective is to minimize the cost incurred by jobs waiting in the system and utilizing the machine. The job flowtime distributions are first derived from which the average flowtimes and the machine completion time are calculated. Efficient computation of the average flowtimes are discussed in detail. The optimization methods and numerical examples are demonstrated.     

采动覆岩中关键层运动对围岩支承压力分布的影响

运用数值模拟方法,主要分析了关键层的破断、关键层相对位置及采深等对围岩支承压力的影响;同时,研究了采空区支承压力的分布规律.研究结果对采场围岩的控制提供了一定的理论依据.     

Flux Jumps and H-T Diagram of Instability for MgB2

We present a study of magneto-thermal instabilities in polycrystalline MgB₂ superconductor, by magnetic hysteresis loop measurements and by investigations of magnetic flux dynamics with a miniature Hall probe. Temperature and magnetic field ranges where the flux jumps may be observed have been determined. On the basis of measurements of the magnetic flux dynamics, an average magnetic diffusivity describing the process of the flux jump is estimated. This parameter is compared with the thermal and magnetic diffusivities calculated on the basis of available data for thermal conductivity, heat capacity and resistivity. It is shown that the estimated value of the field of the first flux jump is influenced significantly by the field dependence of specific heat. In order to explain the observed phenomenon, the temperature reached by the sample during the flux jump at different magnetic fields is calculated.