Mechanical polishing,surface roughness,near‐surface deformation,and electrochemical corrosion of Alloy 690TT

The effects of mechanical grinding/polishing, surface roughness, and near‐surface deformation on the electrochemical corrosion behavior of thermally treated (TT) Alloy 690 were studied in a sodium chloride solution. The X‐ray photoelectron spectroscopy and transmission electron microscopy analyses revealed that mechanical grinding/polishing can change the ratio of the elements at the surface of the as‐received Alloy 690TT specimen by removing its Cr‐rich outer layer and causing deformation at the near‐surface microstructure, something which has a direct impact on the rate of the oxygen reduction reaction (ORR), the pitting potential (E_pit), and the corrosion potential (E_corr) of Alloy 690TT. It was observed that the ratio of Cr in the surface is a significant factor that controls the rate of the ORR and the corrosion parameters such as E_corr. Higher amounts of Cr at the surface accelerate the ORR. The near‐surface deformation shifts the E_pit values towards less positive potentials. It was also found that due to the different near‐surface chemical composition of the as‐received Alloy 690TT specimen compared with the ground and the polished specimens, the surface roughness parameters do not have a regular correlation with the rate of the ORR and the values of the E_corr and the E_pit. Only the passive current density increases when the surface roughness is increased. Copyright © 2015 John Wiley & Sons, Ltd.     

基于VPX架构的测控通信综合测试系统设计

针对传统测控通信系统测试设备种类多、数量大、设备间连接关系复杂,难以满足当前型号任务快速、通用、集成的测试需求,提出了一种基于VPX总线架构的测控通信综合测试系统。系统将以往型号测试采用的前端设备、变频设备、基带设备综合集成,以VPX板卡形式集成到一台机箱,利用背板高速串行总线替代传统设备间电缆,显著简化了系统组成,提高测试设备通用性。     

模型飞行验证系统测控与信息传输技术研究

模型飞行验证系统是为更加有效地开展模型自由飞试验研究而设计的通用试验系统,测控(TT C)与信息传输系统是其信息保障的核心。本文在充分考虑模型自由飞试验特点的基础上,重点研究了模型飞行验证系统研制过程中的测控与信息传输技术,介绍了其工作原理及实现方法,并对部分结果进行分析。     

锚泊状态下船载测控系统对塔相位标校研究

航天器海上测量船是搭载着船载测控系统的海上平台,主要完成对目标的海上测控任务。测量船在新建之时或大修之后均要对搭载的测控系统进行标校,主要是进行海上合作目标校飞。海上校飞过程中锚泊状态下天线对塔相位标校必不可少,对此进行研究有助于提高锚泊状态下对塔相位标校过程的认识,提升船载测控系统的标校精度。研究过程首先分析了我国测量船所采用的差模双通道单脉冲雷达的跟踪原理和天线对塔校相原理,然后再结合锚泊状态下大型海上测量船的运动规律,建立了船体运动对锚泊状态下对塔校相精度影响的数学模型,最后在远场条件下对数学模型进行了的仿真,分析了测量船锚泊时不同运动模式对相位标校的影响,并进一步给出了锚泊状态下船载测控天线对塔校相的建议。     

一种窄波束信号的快速捕获方法

为了适应飞行器不断提高的作用距离和越来越大的动态,采用Ka频段进行飞行器测控是未来的发展方向,但是Ka频段在提供增益的同时增加了信号的捕获难度。针对Ka频段天线波束窄和目标动态大的问题,设计出了一种空间信号快速搜索方法和低信噪比下信号多普勒频率捕获方法。给出了空间目标搜索和多普勒频率捕获的理论分析,并进行了模型仿真。仿真结果表明该方法可以在Eb/N0=0 dB时完成空间目标搜索和多普勒频率快速捕获。     

VC6.0编辑控件的改进设计

为了解决S频段统一测控系统监控软件非法输入的自动处理问题,提出了基于VC6.0[5]的编辑控件[6]改进设计方案。介绍了封装设计[7]、功能设计和类型设计[3]要求,提出了改进设计过程需要考虑的初始化、实时判断和异常处理问题。对所使用到的构造函数重载技术[2]、消息响应技术[1]以及程序判决逻辑[4]进行了解释说明。通过搭建仿真测试环境,对控件进行了性能测试和比对分析,测试结果验证了该设计的可靠性和实用性。     

可修改PSI调制器在数字电视中的应用

本文简述了数字电视中PSI/SI表结构和作用,并举例说明TT6120可修改PSI调制器在数字电视中的应用,具有很强的实用性.     

Latest advances in zwitterionic structures modified dialysis membranes

End-stage renal diseases are affecting many patients and as a result, demand to receive dialysis service is growing annually. Morbidity and mortality rates are reported to be higher in comparison with healthy humans. The reason is reported to be the hemoincompatiblity of blood purification membranes, which hinders patients’ lives. Activation of different immune systems in the body, in case of blood-membrane interaction, results in several side effects, of which cardiovascular shocks have been mentioned to be a major one. Efforts to solve this issue have resulted in different generations of dialysis membranes. Zwitterionic immobilized membranes are the latest (third) generation, which owns a higher degree of hemocompatiblity with more stability of immobilized structures. This critical review intends to cover recent efforts conducted over the zwitterionization of polymeric membrane surfaces with the goal of improving hemocompatibility. Different aspects of third-generation membranes are discussed for a better understanding of the current gap and gathering the knowledge to further develop the field. Accordingly, this critical survey provides an in-depth understanding of blood purification membranes zwitterionization for paving the way for the optimum enhancement of hemodialysis membrane hemocompatibility.     

Gradient estimates and Jackson’s theorem in spaces related to measures

Jackson’s theorem is established in a new kind of holomorphic function space Q_μ related to measures in any starlike circular domain in TT1G55-2-3D/0?wchp=dGLbVlz-zSkWA" alt="View the MathML source" title="View the MathML source" align="absbottom" border="0" height=10 width="17"/>. Particularly, the result covers many spaces including BMOA, Q_p, Q_K, and F(p,q,s) spaces in the unit ball of TT1G55-2-6N/0?wchp=dGLbVlz-zSkWA" alt="View the MathML source" title="View the MathML source" align="absbottom" border="0" height=10 width="17"/>. Moreover, we construct integral operators which give pointwise estimates for the gradient of the difference in terms of the gradient on the boundary. The gradient estimates are independent of the measures in question and give rise to Jackson’s theorem.     

基于STK二次开发的链路测控仿真

在航空航天任务过程中,测控覆盖率高就能提供实时、连续、可靠的信息支持。利用VC结合STK二次开发,建立了测控链路仿真模型。软件利用STK/X模块较好的显示效果与Access模块计算、显示测控链路的余量和测控链路覆盖范围。针对不同的地面站部署,可计算空间飞行器的测控覆盖率。实现VC与STK集成的二次开发可大幅节省了开发时间,该仿真方法对测控系统的设计具有参考价值。