扇形束投影域重建—再投影迭代法

本文所提出的投影域重建——再投影迭代算法可以恢复不完整的扇形束投影数据,从而实现从有限的投影数据重建图象。这种算法把滤波——反投影图象重建过程和再投影的过程纳入一个公式,仅在投影域上估算未知的投影数据,因此避免了重建过程和反投影过程中的插值运算,改善了收敛性,提高了计算精度,缩短了运算时间。模拟实验表明:即使有70％的投影数据丢失,经过两次迭代就能以令人满意的精度恢复丢失的投影数据。     

Temperature effects on the mass flow rate in the SBI and similar heat‐release rate test equipment

In various medium‐to‐large‐scale fire test equipments like the ISO room corner test (RC), and more recently, the single burning item test (SBI) the mass flow rate measurement of the combustion gases plays a key role in the determination of the heat‐release rate and smoke‐production rate. With the knowledge of the velocity profile and the temperature of the flow, the mass flow rate is obtained by measuring the velocity on the axis of the duct. This is done by means of a bi‐directional probe based on the pitot principle. However, due to the variation of the mean temperature and the temperature gradient in any cross section of the duct, introduced by ever changing combustion gas temperatures, the velocity nor the density profile are constant in time. This paper examines the resulting uncertainty on the mass flow rate. Copyright © 2006 John Wiley & Sons, Ltd.     

面流消能近底紊动流速特性的研究(面流消能试验研究之一)

本文主要论述了面流消能五种典型流态近底紊动流速特性,总结出了近底时均流速和紊动强度沿程变化规律,提出了近底紊动流速可能出现的最大瞬时值及相应位置的计算公式。面流消能工程的下游防冲设计中考虑的主要水力参数之一是,消能段近底流速紊动可能出现的最大瞬时值及其相应的部位,但目前国内外研究成果较少。笔者通过水工模型试验重点研究了面流消能各典型流态近底流速及其紊动纵向分量沿程的变化规律,并提出了计算公式,为优化面流设计提供科学依据。     

小方坯连铸机的PLC自动控制

本文对弧型小方坯连铸机工艺与设备进行了分析，介绍了连铸生产的ＰＬＣ控制系统。及其软件设计。     

管外上升R－113流体的沸腾换热试验

详细介绍了Ｒ－１１３流体管外上升流动的沸腾换热试验，包括试验台架、流量计和温度测量的修正，以及试验数据。拟合的换热关系式为ｑ＝５２８（Ｔｗ─Ｔｓ）１．３３。     

β放射性气体浓度计的新分度方法

本文介绍β放射性气体浓度计的一种新的分度方法——泄漏元件排气法。其特点是一只元件可分度放射性气体浓度计的许多读出数(甚至是几个量程),操作方便。     

转移法色交换

将图Ｇ的着色由一种变为中一种，通常用Ｋｅｍｐｅ法以交换。但是，对于某些情况，用此法无效。针对这个问题，本文提出了一种转移法色交换，它适用于平面图着色，方法直观，清晰且有效。     

Integrating scheduling and control functions in computer integrated manufacturing using artificial intelligence

Proper integration of scheduling and control in Flexible Manufacturing Systems will make available the required level of decision-making capacity to provide a flexibly-automated, efficient, and quality manufacturing process. To achieve this level of integration, the developments in computer technology and sophisticated techniques of artificial intelligence (AI) should be applied to such FMS functions as scheduling. In this paper, we present an Intelligent Scheduling System for FMS under development that makes use of the integration of two AI technologies. These two AI technologies — Neural Networks and Expert Systems — provide the intelligence that the scheduling function requires in order to generate goodschedules within the restrictions imposed by real-time problems. Because the system has the ability to plan ahead and learn, it has a higher probability of success than conventional approaches. The adaptive behavior that will be achieved contribute to the integration of scheduling and control in FMS.     

Effect of Channel Changes in the St. Clair River During the Present Century

Periodic man-made changes in the outlet of Lake Huron through the St. Clair River date back to the middle of the last century. These artificial channel changes have been well documented during the present century. They consist of dredging for commercial gravel removal in the upper river during 1908–25 and uncompensated navigation improvements for the 7.6-m (25-ft) and 8.2-m (27-ft) projects completed in 1933 and 1962, respectively. The total effect of these changes on the levels of Lakes Michigan and Huron (hydraulically one lake) and on the upper St. Clair River profile was determined with dynamic flow models. The ultimate effect of the above dredging was a permanent lowering of the Lake Michigan-Huron levels 0.27 m (0.89 ft), which represents a tremendous loss of freshwater resource [32 km³ (7.7 mi³)].     

Yeast exo-β-glucanases can be used as efficient and readily detectable reporter genes in Saccharomyces cerevisiae

Yeast exo-1,3-β-glucanases are secretable proteins whose function is basically trophic and may also be involved in cell wall glucan hydrolytic processes. Since fluorescein di(β-D -glucopyranoside) is a fluorogenic substrate detectable and quantifiable by flow cytometry, it was used for testing the ability of the EXG1 gene product of Saccharomyces cerevisiae and its homologous gene in Candida albicans to function as reporter genes. These open reading frames were coupled to different promoters in multicopy plasmids, and exoglucanase activity quantified at flow cytometry. Exoglucanases were found to be useful tools for the study of promoter regions in S. cerevisiae. This technique has the advantage over other reporter gene systems—such as β-galactosidase fusions—that it does not require permeabilization of yeast cells and therefore it allows the recovery of viable cells—by sorting—after flow cytometry analysis.