Development of a high energy biscuit for use as a food supplement in disaster relief

International aid agencies undertake supplementary feeding programmes following disasters in order to alleviate or prevent protein energy malnutrition. The associated problems include lack of facilities for preparation and distribution of food on site and food hygiene dangers. In response to these factors a biscuit of high calorific value and acceptable organoleptic qualities has been developed. It is currently being used by Oxfam as part of their disaster relief programme in Ethiopia.     

快速高精度除法算法的FPGA实现

为在现场可编程门阵列(FPGA)中实现快速高精度除法,在传统的倒数除法的基础上,提出一种改进算法.对倒数求解采用泰勒级数展开结合优化搜索逼近,求出各个分区间内的拟合一次两项式,再通过一次牛顿迭代提高精度.时序仿真结果表明,以该算法构建的除法器易于在FPGA上实现,时延仅为6个时钟周期,能达到2(-34)的有效精度和86...     

EXPERIMENTAL ESTIMATION OF A SCALING EXPONENT FOR TIP VORTEX CAVITATION VIA ITS INCEPTION TEST IN FULL- ANDMODEL-SHIP

Tip vortex cavitation noise of marine propeller became primary concerns to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model-and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full-and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy.     

正则表达式匹配引擎性能分析

正则表达式具有强大的描述能力,在计算机领域,正则表达式匹配技术应用十分广泛。目前,已经有多个正则表达式匹配引擎,在实际应用中,对于不同的匹配规则集和正则语法,不同的匹配引擎会有不同的性能表现。本文通过对PCRE、Greta、Boost、RE2四种常用正则表达式匹配引擎的性能测试,给出在不用的正则语法情况下的匹配速度,并深入分析不同坏境下适用的正则表达式匹配引擎。对实际系统设计中正则表达式库的选择有指导意义。     

考虑单侧翼缘受载腹板屈曲的不锈钢钢管设计

本文给出了冷成型不锈钢方钢管和矩形钢管在腹板屈曲时的设计公式。研究了两种单翼缘加载的情况,一种是端部单翼缘加载,另一种是内部单翼缘加载,此外还研究了内部加载的情况。采用屈服线理论预测了不锈钢管截面的腹板屈曲强度。屈服线理论模型是在试验中观察到的破坏模式的基础上发展起来的。在屈服线模型基础上采用不同的假定,给出了计算冷成型不锈钢方钢管和矩形钢管的腹板屈曲强度的三种设计方法。其中两种腹板屈曲设计方法是完全采用屈服线分析理论推导出来的,另外一种设计方法是综合理论分析和经验分析得到的。将试验得到的腹板屈曲强度和这三种设计方法得到的屈曲强度进行了对比。结果表明采用纯理论推导得到的设计方法计算得到的腹板屈曲设计强度偏于保守,而综合了理论分析和经验分析得到的设计方法其计算的腹板屈曲设计强度值比较合理,可以用于单翼缘受载时冷成型不锈钢管的设计。     

A framework for modern manufacturing economics

Modern manufacturing economics is an interdisciplinary research subject which deals with the cycles of performance measurement, cost estimation, and decision analysis that are enmeshed with quantification of ill-structured benefits of advanced manufacturing technologies (AMT). This paper proposes a framework of modern manufacturing economics by examining recent research trends of AMT economics. It underscores integrated, quantitative, global, and strategic studies of AMT economics.