Research on assessing compression quality taking into account the space-borne remote sensing images

According to the remote sensing image characteristics,a set of optimized compression quality assessment methods is proposed on the basis of generating simulative images.Firstly,a means is put forward that generates simulative images by scanning aerial films taking into account the space-borne remote sensing camera characteristics(including pixel resolution,histogram dynamic range and quantization).In the course of compression quality assessment,the objective assessment considers images texture changes and mutual relationship between simulative images and decompressed images,while the synthesized estimation factor(SEF) is brought out innovatively for the first time.Subjective assessment adopts a display setup — 0.5mm/pixel,which considers human visual characteristic and mainstream monitor.The set of methods are applied in compression plan design of panchromatic camera loaded on ZY-1-02 C satellite.Through systematic and comprehensive assessment,simulation results show that image compression quality with the compression ratio of 4:1 can meet the remote sensins aDDlication reauirements.     

SITH耐压容量的控制和调节

分析了SITH结构的掺杂电阻率、N－基区厚度、沟道尺寸以及终端结构对正向阻断电压的影响，分析了其横向自掺杂、沟道尺寸、外延层以及相关因素对栅－阴极击穿电压的影响，讨论了如何进行正向阻断电压和栅－阴极击穿电压的控制和调节。     

微滤膜部分堵塞过滤模型的建立和机理探讨

膜过滤机理是目前膜过滤工艺需要研究解决的关键问题之一。为描述微滤过程的速率变化数学模型,通过假设膜通道均为连通的网络型通道,将Kozeny-Carman方程与Darcy方程联立,建立了微滤膜部分堵塞过滤机理模型,并以孔隙率与水力半径为关键因素,推导了基于Darcy方程的微滤速率变化规律。在恒压条件下,通过醋酸纤维素(CA)平板膜死端过滤实验对上述模型进行了验证,在线测定了微滤速率和滤液量随时间的变化关系。结果表明:实验测得的数据和推导的模型基本吻合;且微滤存在Hermans-Bredee的3种机理(即机理指数n=2,3/2,1)以外的堵塞过滤机理,即n=4/3次方的机理。本文提出的部分堵塞过滤机理,可以与传统精密过滤中的基于Poiseuilles方程的堵塞过滤理论一起,应用于包括微-超滤的精密过滤研究中。     

期望信号稳健阻塞的协方差矩阵重构波束形成算法

针对期望信号导向矢量存在失配时自适应波束形成器性能下降的问题,提出期望信号稳健阻塞的干扰噪声协方差矩阵重构算法。首先,构造角度展宽的信号阻塞矩阵,完成回波数据中期望信号的分离,进而利用无污染的回波数据计算准干扰噪声协方差矩阵。接着,对准干扰噪声协方差矩阵做特征分解,借助矩阵投影变换完成干扰噪声协方差矩阵的准确重构。最后,对剔除掉干扰和噪声分量的采样协方差矩阵做特征分解,完成期望信号导向矢量的有效估计。理论分析和仿真结果表明,所提算法不仅具有近乎理想的性能,还具有较低的计算复杂度。     

泡沫封堵能力试验研究

借助岩心驱替流程试验,研究了含油模型水驱之后注泡沫、复合泡沫及聚合物驱后注单一泡沫、复合泡沫的泡沫体系封堵能力,结果表明,单一泡沫驱在水驱残余油条件下,难以形成有效的封堵,而复合泡沫体系在各种残余油条件下均能形成有效的封堵调剖能力,证明复合泡沫体系是一种性能良好的调剖驱油剂。     

二乙二醇乙醚—异氰酸酯封端反应

对二乙二醇乙醚与２,４－甲 二异氰酸酯的封端反应进行了研究,探讨了温度、催化剂及溶剂等对封端反应的影响,利用经外光谱和ＤＳＣ等分析手段进行了表征,结果表明,利用二乙二醇乙醚对２,４－甲苯二异氰酸酯的反应进行顺利,解封温度适中。     

非对称晶闸管的阻断电压

在有效碰撞电离率近似下，出给定正向阻断电压和电流放大系数的AS－CR长基区参数满足的关系式。数值计算结果表明，把此关系与有效碰撞电离率系数和雪倍增因子参数的经验公式相结合，是一种快速、精确设计ASCR正向阻断电压的方法。     

平面型电力电子器件阻断能力的优化设计

利用场限环终端结构及P^ I(N^-)N^ 体耐压结构分析了平面型电力电子器件的阻断能力，提出了一种优化设计阻断能力的新方法，通过将器件作成体击穿器件，使其终端击穿电压与体内击穿电压之间达成匹配，从而可提高器件阻断能力的稳定性和可靠性，并降低器件的通态损耗及成本。最后通过制作具有PIN耐压结构的GTR和引用国外有关文献验证了该方法的正确性。该方法可直接推广到整流器，晶闸管，GTR，IGBT，IEGT和MCT等多种平面型电力电子器件设计中。     

水溶性聚氨酯的合成

以二异氰酸酯、聚醚多元醇为原料，利用二异氰酸酯和聚乙二醇在封端剂的存在下合成了一种水性聚氨酯；探讨了影响预聚反应和封端反应的因素。在促进剂存在下，以亚硫酸氢钠为封端剂反可制得水溶性聚氨酯。     

Analysis of a New Type of Production System

Previous work studied a production system including multiple stations (or workshops) consisting of an entry station, a set of workstations, an exit station, and a central station, which could be arranged in any configuration. The central station was introduced into the production system to relax the environment. In this paper, the central station is eliminated. The entry station and all workstations have limited local buffers. A workstation can choose either a buffer or a kanban mechanism to control its work-in-process (WIP). The production system was modeled as a queueing network with blocking in a general configuration. A symmetrical decomposition approach was developed to analyze the production system. The simulation result shows that the decomposition approach works well. Comparison of the new production systems with modified production systems having a common buffer shows that the key for implementing just-in-time production systems is to reduce the uncertainty.