混凝土重力坝基础排水孔模拟方法对比分析

该文根据以沟代井列法、改进排水子结构法、以缝代井列法以及结点水位约束法等4种常用的模拟排水孔工作的基本原理和方法,以一工程作为实例,开展坝址渗流场数值模拟,并进行对比分析。结果表明,改进排水子结构法能够很精细地刻画排水孔(幕)周围渗流性态,而其它3种方法的精度相对差一些。就模拟过程来讲,前一种方法相对比较复杂,后3种方法则相对简单。     

基础地质在岩土工程勘察中的运用

工程地质勘察技术在原有的基础上有了更大的进步，从勘察人员的职业技术水平到基础勘察设备都有很大的提升。本文主要探析了基础地质在岩土工程勘察中的运用，以期为该领域的有关人士提供一些有意义的参考价值。     

对建筑空调制冷系统施工中管理要点的研究

本文主要从三个不同的环节，阐述了建筑空调制冷系统施工中的管理要点，希望能为今后空调制冷系统施工质量的进一步提升提供一定的参考依据。     

Residents＇ Satisfaction with the Public Housing Unit Features and Its Implications in China

This paper studied the residents＇ level of satisfaction in public housing units in Shenyang of China which aimed to identify how each housing unit feature correlates with the residents＇ overall satisfaction and implication on policy and design. The discussion is based on a questionnaire survey conducted in 2011. This research concluded that more residents were satisfied with the housing unit features than those who were dissatisfied, while some remarkable differences could be observed if comparative analysis between two different public housing types in China were studied. The affordable housing residents are generally more satisfied with housing unit features than those living in low-rent housing. The most dissatisfying feature is the living room, followed by unit size and the floor plan. Additionally, the living room and the floor plans were features which were highly and positively correlated to the residents＇ overall satisfaction of housing unit features. Consequently, improving the living room size and the design of housing unit floor plans would clearly be beneficial to alleviating residents＇ dissatisfaction to the housing units.     

Analysis and spectral characteristics of a spread-spectrumtechnique for conducted EMI suppression

Frequency modulation (FM) and random switching methods have been used for reducing conducted electromagnetic interference (EMI) in power converters. Limited theoretical studies and comparisons of these schemes, however, are available. In this paper, a detailed analysis and the spectral characteristics of a random carrier-frequency (RCF) technique for suppressing conducted EMI in an offline switched-mode power supply are presented. The analysis provides a theoretical platform for studying the characteristics of this random switching scheme. The level of randomness is defined for the RCF scheme and varied in the converter example so that the effects on the power spectra can be demonstrated. Theoretical predictions of the spectral characteristics of this scheme are confirmed with measurements. The RCF scheme has been compared with the standard constant-frequency pulsewidth modulation (PWM) scheme and the FM scheme. Comparisons of their spectral performance show that the RCF scheme has better conducted EMI suppression than the FM and standard PWM schemes     

Preparation of mercaptoacetic acid-capped ZnSe core–shell nanocrystals by hydrothermal method

Mercaptoacetic acid (MMA)-capped ZnSe (ZnSe–MMA) core–shell nanocrystals have been prepared by two-step hydrothermal method using Se and Zn(NO₃)₂ aqueous solution as precursor. The as-prepared ZnSe are zincblende structure with grain size of 4 nm. The MMA-capped ZnSe nanocrystals are more stable and can be preserved long time without oxidation in the air. The ZnSe–MMA core–shell nanocrystals show good absorption for the ultraviolet light.     

Performance Prediction of Carbon Nanotube Bundle Dipole Antennas

A theoretical investigation is carried out for predicting radiation characteristics of single-walled carbon nanotube (SWCNT) bundle dipole antennas based on the distributed circuit parameters and the model of an SWCNT, where the cross section of bundles can be in a circular and a rectangular geometry, respectively. The current distributions in such novel antennas are predicted to investigate the effects of bundle cross-sectional size, tube diameter, tube length, and operating frequency. Furthermore, comparative studies are performed to show the geometry- and frequency-dependent radiation resistance, far-field pattern, and radiation efficiency of some typical bundle dipole antennas, which are numerically confirmed to outperform an SWCNT antenna by 30-40 dB in radiation efficiency.     

An Improved Angle Polishing Method for Measuring Subsurface Damage in Silicon Wafers

提出了一种改进的角度抛光方法来测量硅片的亚表面损伤.其原理是:经过研磨和化学机械抛光后,起保护作用的陪片靠近胶黏剂的一端形成一个无损伤的、完整的劈尖,劈尖的棱边作为测量亚表面损伤的基准;角度抛光的倾斜角可通过劈尖上面产生的干涉条纹准确地测量得到.采用这种方法可以方便、准确地测量硅片由切割、研磨和磨削引起的亚表面损伤,其能够测量的最小损伤深度为几百纳米.