MRIL-Prime核磁共振测井仪

MRIL -Prime是Halliburton公司推出的最新一代的核磁共振测井仪器。该仪器吸收了CMR和MRIL -C型仪器的优点 ,改进了其不足 ,采用 5个频带 9个不同的频率 ,一次下井可进行多种模式的测量 ,同时获得标准T2谱、移谱、差谱等信号 ,既提高了测井速度 ,又获得了更多的测井信息 ,同时数据精度也大大提高。文章介绍了该仪器的结构、主要技术指标、电子线路、电容和探头特征、工作原理及实现方法     

AKIMA方法在EXAFS谱解析中的应用

解析扩展Ｘ射线吸收精细结构谱（ＴｈｅＥｘｔｅｎｄｅｄＸ－ｒａｙＡｂｓｏｒｐｔｉｏｎＦｉｎｅＳｔｒｕｃｔｕｒｅＥＸＡＦＳ）的一种方法是曲线拟合，在曲线拟合中，能量阈值Ｅ０的确定有着很重要的意义，同时也有相当的难度，本文应用ＡＫＩＭＡ平滑数据点方法达到了对Ｅ０在数学意义上的精确求解，数据分析结果表明，这种方处理结果是令人满意的。     

一种新的时变大系统递阶控制求解方法

研究了一种新的大系统求解方法,利用Taylor级数的性质,将大系统时变递阶控制问题 转化为代数方程的求解问题.该方法简单,易于编成计算机程序.算例表明了它的有效性.     

A comparative study on coronary angiography and exercise ECG testing

42 patients with chronic urinary retention caused by BPH were treated by means of Mesh-like tubular stent placing from August 1993 to August 1994. The mesh-like tubular stent was made of nickel titanium alloy in sizes of 2.0 x 1.5 cm, 2.5 x 1.5 cm, 3.0 x 1.5 cm respectively. Under direct vision the stent was placed with the deployment tool. The desirable position of the stent is 0.3-0.5 cm proximal to the internal urethral orifice, 0.5 cm distal to the verumontanum. In 38 patients followed up for 1-6 months, 34 were succesful with an effective rate of 80%. IPSS, PUFR, RUV after 1, 3, 6 months of placement were 8.5 +/- 4.4, 6.8 +/- 3.5, 7.1 +/- 5.2; 12.5 +/- 6.0 ml/s, 14.0 +/- 5.2 ml/s, 14.4 +/- 8.1 ml/s; 43 +/- 11.5 ml, 47.4 +/- 13.3 ml, 44.5 +/- 15.7 ml respectively. Four stents were taken away transurethrally in the unsuccessful cases. The results indicat that there are no serious complications except for shorttime hematuria, fever, and bladder irritation. The success depends chiefly upon exactly meassuring the length of prostatic urethra, selecting the rational size of the stent, and correctly placing the stent.     

双面肖特基势垒型GaAs粒子探测器的电特性研究

研究了有源面积为９ｍｍ２的双面肖特基势垒ＧａＡｓ粒子探测器的电特性。器件工艺简单，结构新颖，反向耐压高于３００Ｖ，反向漏电流密度低（９１ｎＡ／ｍｍ２），该器件能经受能量为１．５ＭｅＶ、剂量为１０００ｋＧｙ的电子照射，电特性正常，是一种抗辐照的粒子探测器。     

锻钢退火炉消烟除尘技术改造

介绍了锡钢集团公司锻压分厂车底式热处理退火炉消烟除尘综合治理改造情况。包括烧嘴重新选型、配置，增设空气预热器及重油加热系统，并将下排烟改为地上排烟。改造的主要目的是消烟除尘，提高产品退火质量，提高炉子装备水平及节省燃油消耗。改造后运行结果基本达到了预定目标。     

TiO_2对ZrO_2－NiCr金属陶瓷烧结特性和相稳定性的影响

本文研究了ＴｉＯ２掺入对ＣａＯ稳定ＺｒＯ２（简称ＣａＳＺ－ＮｉＣｒ）金属陶瓷烧结特性的影响，测定了ＣａＳＺ－ＮｉＣｒ－ＴｉＯ２金属陶瓷烧结样品的密度和显微硬度，结果表明，ＴｉＯ２的掺入能提高ＣａＳＺ－ＮＩＣｒ金属陶瓷的烧结密度和显微硬度，对ＣａＳＺ－ＮｉＣｒ金属陶瓷有助烧结作用．金相观察表明，ＴｉＯ３的掺入改变了ＮｉＣｒ相在金属陶瓷中的形貌，说明了ＮｉＣｒ与ＣａＳＺ的浸润性有一定的改善．ＸＲＤ和ＥＰＭＡ分析结果显示，ＴｉＯ２偏聚在ＮｉＣｒ金属相中，不影响ＣａＳＺ的稳定性．     

微机硬件环境与安全

微机硬件的运行环境和硬件安全是计算机网络信息系统能够正常运行的基础,硬件的运行环境和安全直接影响着网络信息系统的安全。而来自于环境干扰、设备自然损坏、自然灾害等因素给微型计算机带来了安全威胁。本文介绍了微机运行的硬件的环境要求、硬件的安全威胁,并提出了用来实现信息安全的硬件安全技术方法。     

高坝泄洪诱发场地振动响应分析及传播规律

为研究高坝泄洪诱发场地振动的问题,提出一种基于黏弹性人工边界的有限元数值模拟和水力学模型试验相结合的方法计算场地振动响应。以国内某工程为例,计算不同工况下场地振动响应,分析泄洪量和泄洪调度方式对场地振动的影响,揭示不同岩体条件下振动波的传播规律。结果表明:该工程各种泄洪方式都不会对周边居民的生活造成影响;泄洪量越大,下游场地振动响应越大,当3个溢洪洞泄洪条件一致时,采用2号洞泄洪最不利;同等泄洪条件下,采用4洞均分泄洪的振动响应小于按设计开度泄洪的振动响应;模型范围内放大振动波的主因是断层左右岩体性质的差异,断层的存在进一步加大了放大效应。     

Information analysis of single photon emission computed tomography with count losses

An analysis is presented of the information transfer from emitter-space to detector-space in single photon emission computed tomography (SPECT) systems. The analysis takes into account the fact that count loss side information is generally not available at the detector. Side information corresponds to the number gamma-rays lost deleted due to lack of interaction with the detector data. It is shown that the information transfer depends on the structure of the likelihood function of the emitter locations associated with the detector data. This likelihood function is the average of a set of ideal-detection likelihood functions, each matched to a particular set of possible deleted gamma-ray paths. A lower bound is derived for the information gain due to incorporating the count loss side information at the detector. This is shown to be significant when the mean emission rate is small or when the gamma-ray deletion probability is strongly dependent on emitter location. Numerical evaluations of the mutual information, with and without side information, associated with information-optimal apertures and uniform parallel-hole collimators are presented.