耿达电站首部枢纽运行中的泥沙淤积及清污处理

简要地介绍了渔子溪二级水电站首部枢纽在10多年运行管理中的泥沙淤积及清污的处理措施。     

A technique for extracting physiological parameters and therequired input function simultaneously from PET image measurements:theory and simulation study

Positron emission tomography (PET) is an important tool for enabling quantification of human brain function. However, quantitative studies using tracer kinetic modeling require the measurement of the tracer time-activity curve in plasma (PTAC) as the model input function. It is widely believed that the insertion of arterial lines and the subsequent collection and processing of the biomedical signal sampled from the arterial blood are not compatible with the practice of clinical PET, as it is invasive and exposes personnel to the risks associated with the handling of patient blood and radiation dose. Therefore, it is of interest to develop practical noninvasive measurement techniques for tracer kinetic modeling with PET. In this paper, a technique is proposed to extract the input function together with the physiological parameters from the brain dynamic images alone. The identifiability of this method is tested rigorously by using Monte Carlo simulation. The results show that the proposed method is able to quantify all the required parameters by using the information obtained from two or more regions of interest (ROIs) with very different dynamics in the PET dynamic images. There is no significant improvement in parameter estimation for the local cerebral metabolic rate of glucose (LCMRGlc) if there are more than three ROIs. The proposed method can provide very reliable estimation of LCMRGlc, which is our primary interest in this study     

热采水平井整体开发草13块砂砾岩薄层特稠油

热采水平井技术是科学有效开发稠油油藏的重要手段。以胜利油田草13块为例，系统论述了利用热采水平井整体开发具有边底水的砂砾岩薄层特稠油油藏的开发程序和研究方法。在油蒇精细描述的基础上，通过热采筛选、产能评价、直井和水平井数值模拟、开发方式优化及指标预测等油藏工程研究技术方法，综合论证了利用热采水平井整体开发草13块的必要性和可行性，总结了砂砾岩薄层特稠油油藏水平井油藏工程设计中应遵循的原则，并在生产实践中见到明显效果，为胜利油田其它区块和类似油田的开发提供了借鉴和指导。     

四气门汽油机缸内气流运动LDA测量结果的小波分析方法

主要采用小波分析方法研究了四气门汽油机缸内空气运动的频率结构。在一台四气门汽油机上 ,使用激光多普勒测速仪 (L DA)在倒拖工况下测量了气缸内的滚流运动 ,使用了 MATL AB 5 .1数学工具包中的小波分析方法对试验结果进行数据处理 ,得到了时域和频域分解速度信息。从这些信息中可以清楚地看到滚流 (低频湍流 )在压缩末期破碎并形成高频湍流的现象     

双迭片弯曲压电陶瓷换能器及振动模态分析测量

介绍了双迭片弯曲压电陶瓷换能器的制作及边缘固定金属压电陶瓷双迭片弯曲振动，并利用有限元分析了换能器的谐振模式，采用激光多普勒干涉仪对换能器的谐振特性以及振动速度和位移分布进行了测量和分析，结果表明：换能器空载性能良好，通过有限元分析与先进测量手段的结合，能够对换能器器件的制作与分析进行指导。     

Hemodynamic structure of antiorthostatic reactions: relationship of mechanical activity of the heart and arterial pressure

This paper is an update on the issue of dental student debt and provides additional data and an exploration of continued trends which were outlined by Douglass and Fein in the 1995 IOM study of The Future of Dental Education. Dental school tuitions have continued to increase at rates at or above the consumer price index. These tuition bills are increasingly being met by debt financing on the part of the students. These trends are described and then related to recent data on the future plans of dental school seniors. The second part of the paper will provide new updated date on dentists' incomes and analyze the trend in dental fees versus the consumer price index. The final section provides a summary of pay back mechanisms currently being offered to students.     

建筑容积率对地价影响规律及修正方法研究

在分析建筑容积率对土地价格影响的作用机制和规律的基础上，针对目前土地估价工作中，容积率修正系数确定存在的问题，提出新的容积率修正思路和方法。     

新型缆用热熔胶的研制

分析了通信线缆用 YH- 4热熔胶组成原料的性能和作用 ,找出影响耐环境高温性能的主要原因 ,并对新研制出的耐环境高温性能 YH- 5热熔胶作了一些分析和探讨 .     

含钇奥氏体基堆焊焊条堆焊层研究

针对高温、磨损、热疲劳工况下服役零件的失效，研制了一种含稀土元素钇的奥氏体基沉淀强化型堆焊焊条，并对堆焊层组织与性能进行了较系统的研究。     

人工接地装置设计方法分析

本文系统地论述了人工接地装置的设计方法,修正了现有文献中有关论述的缺点和错误,提出了通过迭代求解方程组来设计人工接地装置的新方法。