Strain analysis of moving objects using a Fourier transform grid method

There is no good method to measure the shape and the strain distributions of a structure changing with time. We have previously proposed the Fourier transform grid method (FTGM) to measure the three-dimensional shape and surface strain distributions of stationary objects by analysing the two-dimensional grating images recorded with two cameras. In the stereoscopic method, it is very important to determine the accurate geometric parameters of the camera system. In this paper, the positions and the directions of cameras are accurately determined using the FTGM applied to images of a reference object on which a two-dimensional grating is drawn. Applications for analysing shape and strain distributions of vibrating rubber plates and a moving human skin are shown.     

晶须取向对SiCw／Al复合材料切削表面质量的影响

切削与晶须取向方向间的夹角对ＳｉＣｗ／Ａｌ复合材料切削表面质量有很大影响。当切削角为４５°时，晶须拔出和转动现象均较少，复合材料切削表面粗糙度最低。当切削角为１３５度时，晶段转动造成的撕裂破坏程度很大，复合材料切削表面粗糙度最大。     

高温超导研究的新进展

本文简要回顾了一年来高温超导的新进展，特别介绍和讨论了新型高温超导体系和线材、带材、块材及薄膜应用的发展情况。     

李子溪流域水土流失及泥沙输移规律初步研究

为了探讨长江上游流域水土流失及泥沙输移规律，选取嘉陵江中游的支流李子溪为典型流域进行分析研究，在实地调查，野外测验及应用１９６０年－１９９１年实测降雨、径流、输沙资料的基础上，利用单因子相关分析和多因子回归分析，分别建立了输水利沙量、最大输沙率计算方程。在此基础上，参照径流瞬时单位线原理，以线性时不变系统为基础，建立输沙瞬时单位线模型。通过输沙单位线与时段净侵蚀量的卷积得到流域出口断面的输沙率过程     

煤矿许用毫秒延期电雷管研究

文中对影响煤矿许用毫秒延期电雷管沼气安全性与延期时间精度的因素进行了研究。应用正交设计研制了新的延期药配方，确定了合理的雷管结构及装配工艺参数，产品性能达到ＧＢ８０３１《工业电雷管》的规定。     

用试井方法确定注水后地层渗透率的变化

大港油田已进入开发中后期，高含水油田占73％，开发初期的一些参数已不适合现在开发的需要。研究出一套用试井方法确定注水以后地层渗透率变化的方法，对大港油田的增储上产具有重要意义。     

Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design.     

Emergy account for biomass resource exploitation by agriculture in China

On the basis of Odum's ecological economic measure of emergy as embodied solar energy, a system account of biomass resource exploitation by agriculture in China 2004 is developed in this paper, which supplements a former study on corresponding long-term historical trends during 1978 to 2000 (Chen et al., 2006. Emergy-based analysis of the Chinese agriculture. Agriculture, Ecosystems and Environment 115, 161–173). The aggregate fluxes and indicators for biomass resource exploitation in China 2004 are calculated and illustrated when compared with those for 2000 to elucidate the latest status of the Chinese agriculture as the exploitation sector for biomass resource. Data sources and algorithm are presented in detail as basic references for related analysis involving the ecological economy of biomass exploitation in agriculture.     

第三只眼看进品保健品

许多国家大多没有严格意义上的保健品概念，美国等国家将其统称为“功能食品”。我国应用“保健品”一词，旨在将其与药品和食品两大门类区分开来。美国的“保健品”发展速度和规模比较大，同时由于其先进的制造和科研技术，引领着世界功能食品的潮流。随着我国社会的发展，保健品的生产和研发也逐步赶上国际的步伐，而大量的进口保健品也已经进入寻常百姓家。     

A time-based energy-efficient analog-to-digital converter

Dual-slope converters use time to perform analog-to-digital conversion but require 2/sup N+1/ clock cycles to achieve N bits of precision. We describe a novel current-mode algorithm that also uses time to perform analog-to-digital conversion but requires 5N clock cycles to achieve N bits of precision via a successive subranging technique. The algorithm requires one asynchronous comparator, two capacitors, one current source, and a state machine. Amplification of two is achieved without the use of an explicit amplifier by simply doing things twice in time. The use of alternating voltage-to-time and time-to-voltage conversions provides natural error cancellation of comparator offset and delay, 1/f noise, and switching charge-injection. The use of few components and an efficient mechanism for amplification and error cancellation allow for energy-efficient operation: in a 0.35-/spl mu/m implementation, we were able to achieve 12 bit of DNL limited precision or 11 bit of thermal noise-limited precision at a sampling frequency of 31.25 kHz with 75 /spl mu/W of total analog and digital power consumption. These numbers yield a thermal noise-limited energy efficiency of 1.17 pJ per quantization level, making it one of the most energy-efficient converters to date in the 10-12 bit precision range.