测量系统中20位精度带通∑-△调制器的设计

设计了一种用于测量系统的20位精度带通∑-△调制器。采用低失真离散时间单环4阶1比特量化结构,以实现高精度的指标。对带通调制器中最关键的模块-谐振子进行了研究,设计了一种对电容非线性和失配不敏感并具有精确谐振频率的高Q值谐振子。仿真结果表明,该调制器在100kHz中频处20Hz带宽内实现了20位分辨率。本调制器采用AMI0．35μm标准CMOS工艺实现,整个调制器的总面积仅为2．5mm^2,在3．3V供电电压下,调制器的总功耗仅为4mW。     

消费者属性对产品造型相似度认知的影响

目的 研究消费者属性对产品造型相似度认知的影响,为优化产品造型空间,提高人们对其认知的一致性提供依据。方法 首先,采用传统的方法,筛选出四十三个家用加湿器样本,构建产品造型空间,邀请七十三位被试,根据造型相似度将其进行多层分类,获取样本间造型相似度数据及被试属性数据;其次,基于轮廓分析法,依次分析不同属性下各组被试对各样本造型相似度认知的一致性;最后,根据异常样本的分布情况,分析各属性对产品造型相似度认知的影响程度。结论 生活形态属性对被试产品造型相似度认知的影响显著,异常率达20%以上,并且强于人口综合特征的影响;学历、性别、专业背景则基本无影响。应引入生活形态因素,检验人们对产品样本造型认知的一致性,进一步优化产品造型空间。     

Screening of 42 Bacillus isolates for ability to ferment soybeans into dawadawa

Forty-two cultures of Bacillus species isolated from soybean dawadawa were screened for their proteolytic activity on Skim Milk Agar, amylolytic activity on Starch Agar, and ability to grow on Soybean Agar. Distinct differences were observed between the cultures for all the criteria. Eleven isolates were selected for laboratory fermentation trials and each produced soybean dawadawa which was found acceptable by a taste panel. The pH of the samples, which increased from 6.37-6.58 to 8.22-8.85 during fermentation, were significantly different at P< or =0.05 for the different cultures. In the fermented samples, Bacillus counts exceeded 10(9) cfu/g, with the population of only one sample being significantly different at P< or =0.05. A market focus group familiar with soybean dawadawa selected Bacillus subtilis 24BP(2) and B. subtilis FpdP(2) as the best potential starter cultures. A taste panel found no significant differences in overall acceptance between soybean dawadawa either fermented spontaneously or with B. subtilis 24BP(2) and also between soybean dawadawa fermented with either B. subtilis 24BP(2) or B. subtilis FpdP(2).     

Bioprocess engineering of microalgae to produce a variety of consumer products

Microalgae biotechnology has recently emerged into the lime light owing to numerous consumer products that can be harnessed from microalgae. Product portfolio stretches from straightforward biomass production for food and animal feed to valuable products extracted from microalgal biomass, including triglycerides which can be converted into biodiesel. For most of these applications, the production process is moderately economically viable and the market is developing. Considering the enormous biodiversity of microalgae and recent developments in genetic and metabolic engineering, this group of organisms represents one of the most promising sources for new products and applications. With the development of detailed culture and screening techniques, microalgal biotechnology can meet the high demands of food, energy and pharmaceutical industries. This review article discusses the technology and production platforms for development and creation of different valuable consumer products from microalgal biomass.     

考虑容量约束的配电系统可靠性评估

提出了一种考虑线路容量约束的配电系统可靠性评估模型,并开发了其软件。可靠性评估通过故障影响分析实现。这样,开发的软件既可评估全部失去连续性事件的可靠性,又可以评估部分失去连续性事件的可靠性。可靠性指标是：系统平均停电频率、系统平均停电持续时间、用户平均停电频率、用户平均停电持续时间、平均供电可用率、缺供电量、平均缺供电量。经对IEEE配电测试系统DRTS的测试表明,该软件是有效、可用的。     

Does financial development lower energy intensity?

The growth-induced effects of financial development have been well-established in the empirical literature, as well as the significance of financial development to energy demand behavior. However, the empirical evidence on the relationship between financial development and energy intensity remains sparse in the literature. Given the multifaceted nature of the effects of financial development, the proposed relationship seems a complex one and warrants an empirical investigation. Using the case of Ghana, this study provides an empirical answer to the question: does financial development lower energy intensity? To provide solid grounds for either rejection or acceptance of the null hypothesis, this study performed several robustness checks. Generally, the evidence revealed that financial development lowers energy intensity. Further, the results revealed that the price of energy, trade liberalization and industry structure play significant roles. These results have important implications for the design of macro energy efficiency policies and the creation of a ‘Green Bank’.     

An ultrasonic collision detection system

Robots in manufacturing are increasingly being called on to do complex tasks that require intelligence beyond merely following a preprogrammed path. In robotic assembling of mechanisms, welding, machine tending and other tasks, sensing enables robots to adapt to their environments. In this research, an ultrasonic collision detection system for an industrial robot was designed, constructed and tested. Two ultrasonic transducers and ranging modules were mounted on the robot wrist to detect and prevent collisions with objects placed in the end effector's path. Experiments were conducted to determine objectto-robot distance as a function of robot speed after the robot had stopped. Two robot motions and two loads were studied. Statistical methods of stopping distance vs. robot speed are presented and will be useful in planning robot tool paths. This ultrasonic collision detection system can be used on stationary and mobile robots, automatic-guided vehicles, and other manufacturing applications.