CCD相机调制传递函数的测试原理分析

对于CCD相机的空间分辨率特性,通常用调制传递函数来表征.基于调制传递函数理论分析值与具体的实验测试值存在差别,分别对分辨率板在焦平面所成的像与CCD像元之间的偏移量和积分时间内被摄物体与相机的相对运动产生的像移对相机调制传递函数的影响进行了分析.讨论了调制传递函数与对比调制传递函数之间的联系和区别.     

Theoretical and Experimental Insight into the Mechanism for Spontaneous Vertical Growth of ReS2 Nanosheets

Rhenium disulfide (ReS₂) differs fundamentally from other group‐VI transition metal dichalcogenides (TMDs) due to its low structural symmetry, which results in its optical and electrical anisotropy. Although vertical growth is observed in some TMDs under special growth conditions, vertical growth in ReS₂ is very different in that it is highly spontaneous and substrate‐independent. In this study, the mechanism that underpins the thermodynamically favorable vertical growth mode of ReS₂ is uncovered. It is found that the governing mechanism for ReS₂ growth involves two distinct stages. In the first stage, ReS₂ grows parallel to the growth substrate, consistent with conventional TMD growth. However, subsequent vertical growth is nucleated at points on the lattice where Re atoms are “pinched” together. At such sites, an additional Re atom binds with the cluster of pinched Re atoms, leaving an under‐coordinated S atom protruding out of the ReS₂ plane. This under‐coordinated S is “reactive” and binds to free Re and S atoms, initiating growth in a direction perpendicular to the ReS₂ surface. The utility of such vertical ReS₂ arrays in applications where high surface‐to‐volume ratio and electric‐field enhancement are essential, such as surface enhanced Raman spectroscopy, field emission, and solar‐based disinfection of bacteria, is demonstrated.     

舰载无源综合脉冲/孔径雷达及其若干关键问题

本文根据综合脉冲/孔径雷达采用多个天线同时向全空域辐射多个载频信号,而在接收端通过信号处理获得发射方向图的特点,提出一种新的雷达体制——舰载无源综合脉冲/孔径雷达.该雷达既利用在岸上发射、在舰船上接收而构成岸-舰双/多基地"广播式"雷达,又由于在接收站不发射信号而相当于无源定位.本文介绍该雷达的基本组成、工作原理及其特点;分析其性能;讨论该雷达需解决的关键问题.     

用AFM导电探针在n-Si(111)表面进行纳米加工的机理研究

本文介绍了在AFM针尖与氢钝化硅表面之间施加电场作用对硅表面进行修饰的纳米加工方法，重点讨论了加工机理。实验考虑了样品的表面状态，周围大气状况，所加电压的极性、大小和加压方式等影响纳米加工的因素。对机理的研究表明，针尖和样品之间发生的是场致电子发射而非热电子发射，电流热效应增强粒子的扩散能力，提高了电化学反应速度。最后给出了电场诱导阳极氧化扩散增强的加工机理。     

多入口集群的调度器失效接管模型与实现

文章基于多级心跳模型，提出并实现了多入口集群调度器的环形、专用和全备份三种连接表同步模型，通过将失效节点模值指定给备份节点实现失效接管，将正常节点的连接记录和模值转移新节点实现扩展。试验表明，该方案具有很好的容错效果和扩展性。     

Design and construction of river crossing tunnel beneath Tachia River,Taiwan

Due to the impact of the 1999 Chi-Chi earthquake (ML = 7.3) and the following typhoon induced heavy rainfalls and floods, the tailrace tunnel of the Kukuan Hydropower Plant was severely blocked and must be realigned and rebuilt. The new tailrace tunnel is 1991 m long with a 140 m section passing underneath the Tachia River, where the shallowest rock cover is 3.5 m. In view of the common phenomenon that weak zone developed along river channel and debris accumulated on river bed, the ground improvement from the surface to the tunnel is difficult. Therefore, a construction shaft, a water sealing pre-grouting plan and a special supporting system were designed to prevent the potential water inflow when tunneling underneath the Tachia River. In the construction phase, adequate excavation cross sections, support elements, auxiliary treatments, and water sealing grouting methods were selected to overcome the difficult ground condition encountered. The experience learned from this successful case can be a valuable reference for the design and construction of similar river crossing tunnels in the future.     

Key project management practices affecting Singaporean firms’ project performance in China

Foreign (non-mainland Chinese) architectural, engineering and construction (AEC) firms may face difficulties managing construction projects in China because they are unfamiliar with this new operating environment. This study investigates project management (PM) practices adopted by Singaporean AEC firms in China. It determines the performance level of their projects in China; identifies PM practices that led to better performance; and recommends key PM practices that could be adopted by foreign AEC firms in China to achieve project success. A structured questionnaire was designed and data were collected via a self-administered postal and email survey, targeting Singaporean AEC firms that had undertaken and managed projects in China. The study finds that certain PM practices do indeed affect project performance. The most important of these are practices relating to scope management, such as controlling the quality of the contract document, quality of response to perceived variations and extent of changes to the contract. It is recommended that foreign firms adopt some of the PM practices highlighted in this study to help them achieve better project performance in China.     

"十二五"规划与航运物流业的绿色发展

该文通过"十一五"和"十二五"规划的对比分析,总结了两个阶段规划在指导思想和目标上的差异,并根据"十二五"对绿色发展的要求,结合港航物流业的特点,厘清了港航物流业的绿色发展变化,并提出了在绿色要求下的港航物流业的发展思路和发展方向.     

丙烯酸酯压敏胶粘剂的合成

介绍了丙烯酸酯压敏胶粘剂的合成方法和性能特点，分析了影响产品性能的四个主要因素，即原料配比、引发剂用量、聚合温度、加水量，提出了各因素对产品性能影响的原因和结果，并对如何提高产品性能进行了探讨。