影像医学发展动向和面临问题

本文概述了现代医学影像技术的进展,分析了CT(计算机断层射线摄影)、DSA(数字减影技术)、MRI(磁共振成像)、SPECT(单正电子发射型体层摄影)以及各种超声成像技术等新技术的特点和适用范围,作者强调应提高医务人员的修养,把这些先进技术和基本诊断方法结合起来,以充分发挥现代医学影像技术的乍用。     

微区电化学测量技术在金属电偶腐蚀中的应用

微区电化学测量技术可在微米级甚至亚微米级尺度对金属电偶腐蚀进行原位检测，为深入研究金属电偶腐蚀提供了新途径。介绍了金属电偶腐蚀的基本原理及其主要影响因素，综述了丝束电极技术(WBE)、局部电化学阻抗谱技术(LEIS)、扫描振动电极技术(SVET)、扫描电化学显微技术(SECM)、扫描开尔文探针技术(SKP)等常用的微区电化学测量技术的优缺点及应用现状，最后对其未来发展进行了展望。     

聚合物流体拉伸流变测量技术的进展

介绍了近年来应用较广的4种聚合物流体拉伸流变测量技术:Meissner拉伸流变技术(RME)、改进旋转流变技术(MRR)、纤维撕扯流变技术(FSR)、Sentmanat拉伸流变技术(SER),分析和总结了它们的结构原理、发展趋势和应用中存在的问题。     

微区电化学方法在电偶腐蚀领域的应用

概述了近些年来微区电化学测量技术在电偶腐蚀方面的研究进展,包括丝束电极技术(WBE)、扫描电化学显微镜(SECM)、扫描振动参比电极技术(SVET)、局部电化学交流阻抗谱(LEIS)、扫描开尔文探针(SKP)等微区电化学测量技术的应用状况,并对其未来的发展及应用进行了论述。     

金属零件3D打印技术研究进展

金属零件3D打印技术是整个3D打印体系中最为前沿和最有潜力的技术,是增材制造的重要发展方向。简述了3D打印工艺中适用于金属材料的工艺,主要包括选择性激光烧结(SLS)技术、选择性激光熔化(SLM)技术、选择性激光熔覆(SLC)技术、层叠法成型(LOM)技术、电子束熔覆技术。讨论了各工艺特征、存在问题以及研究进展。     

多媒体技术在教育教学中的作用

首先介绍了多媒体技术,然后重点介绍了多媒体技术在教育过程中的七大作用如利用计算机媒体的多样性,提高学生的学习兴趣和积极性;利用多媒体计算机的交互性,发挥学生的智力因素等等,最后对其前景作了展望.多媒体(Multimedia)技术是指把文字(Text)、音频(Audio)、视频(Video)、图形(Graphic)、图像(Images)、动画(Auimation)等多种媒体信息通过计算机进行数字化采集、获取、压缩/解压缩、编辑、存储等加工处理和控制,再以单独或合成形式表现出来的一体化技术。     

国内P2P网络热点技术研究

对等(Peer-to-Peer、P2P)网络是近年来互联网上的研究热点之一,而且巳经运用到了商业领域,并且取得了巨大的成功.本文通过大量的文献资料调研,总结分析了近期国内P2P网络研究技术的进展和成果.首先,着重分析了P2P网络中的几个热点技术:(1)资源的搜索与定位技术(2)P2P网络拓扑匹配技术(3)P2P资源复制技术(4)P2P流媒体技术(5)P2P网络安全技术.通过这些分析和介绍,可以更好的了解国内P2P网络的研究热点和发展趋势.     

膜分离在放射性废水处理中的应用

由核设施产生的放射性危害是众所周知的,采用各种分离技术来浓集放射性核素,防止其向环境扩散。综述了膜分离技术在放射性废水处理中的最新进展,主要包括微滤(MF)、超滤(UF)、纳滤(NF)、膜蒸馏(MD)、反渗透(RO)、支撑液膜(SLM)等方法。     

粉末钛合金3D打印技术研究进展

粉末钛合金3D打印技术以低成本、易成形、柔性化制备、零件性能优异等优势,近年来成为钛合金近净成形制造领域的研究热点。总结了国内外粉末钛合金3D打印技术的研究进展,包括激光熔化沉积成形技术(LMD)、激光选区熔化成形技术(SLM)、电子束选区熔化成形技术(SEBM)。比较研究了3种成形技术制备的钛合金的组织特点及力学性能,并讨论了粉末钛合金3D打印技术的市场化现状与未来发展趋势。     

浅谈新形势下加强市(地)、县级计量技术机构信息化建设

本文首先介绍了本地区内市(地)、县级计量技术机构信息化建设的的现状和加强信息化建设的的必要性,并总结了目前市(地)、县级计量技术机构信息化建设中存在的主要问题,最后提出了笔者对市(地)、县级计量技术机构信息化建设的建议。     

核电站穹顶内热环境的数值模拟

以CPR1000核电站R55区穹顶为研究对象,基于计算流体力学(CFD)技术,应用P-1辐射模型对穹顶内部温度场进行了3D稳态数值模拟与实验验证。结果表明:6月26日6个时刻,空穹顶内Z=11m处的温度模拟值与实测值吻合良好,最大相对误差为3.23%,平均相对误差为1.05%;9:00穹顶内垂直方向温度分布梯度明显,最大温差达到6℃。P-1辐射模型模拟太阳辐射对核电站穹顶内热环境的影响是可行的。     

Thermal snapping of functionally graded materials plates

The nonlinear behavior of functionally graded materials (FGM) plates exposed to a high temperature environment on one side of the surface is investigated here using neutral surface-based first-order shear deformation theory. The material considered here is graded in the thickness direction and a simple power law based on the rule of mixture is introduced to study the temperature dependent effective material properties. Furthermore, the position of thermal stress-resultant is determined based on realistic temperature field across the thickness of the plate whereas the reaction resultant is assumed to act along the mid-surface. The nonlinear governing equations derived based on von Kármán assumptions are solved using Newton–Raphson technique to analyze the nonlinear behavior of FGM plates under different temperature gradient.     

降低燃气轮机空气进口温度提高发电功效的方法

燃气轮机的性能与环境温度密切相关,环境温度越高,燃气轮机的出力越低,因此,降低燃气轮机的空气进气温度,可提高其发电功率和效率。本文简要的从热力学角度分析其原因,同时介绍降低燃气轮机空气进口温度的方法。     

航天结构材料低温力学性能测试技术

概述了航天结构材料在深温条件下的力学,物理特性及深低温和学性能研究的内容和特点,强调了液氢温度介质条件下,结构材料力学行为的特殊性。介绍了国内外液氢介质条件下力学性能测试技术。     

Model and Experimental Characterization of the Dynamic Behavior of Low-Power Carbon Monoxide MOX Sensors Operated With Pulsed Temperature Profiles

Wireless sensor networks for home automation or environment monitoring require low-cost low-power sensors. Carbon monoxide (CO) metal-oxide (MOX) sensors could be suitable in terms of device cost, but they show some severe limits, such as the need to be heated, which means large power consumption and the need for complex and frequent calibration procedures, which increases the overall cost. This paper investigates the possibility to partially overcome these limits by a low-cost detection system based on a suitable commercial sensor (TGS 2442, Figaro, Inc.) and an ad hoc measurement technique exploiting specifically tailored temperature profiles. To this aim, the authors study the dynamic behavior of low-power CO MOX sensors operated with pulsed temperature profiles by means of two approaches: 1) sensor modeling and 2) experimental evaluation. To analyze how the sensor dynamic response changes as a function of the CO concentration, the authors individuate a temperature profile, which ensures satisfactory sensitivity to the target gas and very low power consumption. Moreover, some parameters describing the sensor response shape are selected, which prove to be significant in terms of both robustness to environmental conditions and calibration simplicity.     

Wideband injection-locked frequency divider based on a process and temperature compensated ring oscillator

The authors propose a ring-based injection-locked frequency divider (ILFD) incorporating a novel process and temperature compensation technique. The core of the ILFD consists of a process and temperature compensated ring oscillator based on modified symmetric load delay elements. Measurement results show that the natural frequency of oscillation of the ring oscillator varies only 4.4% across six different chips and for a temperature range of 0-80°C. The ILFD possesses a wide locking range over process corners as well as a wide temperature range because of the proposed compensation technique and the incorporation of the delay cell architecture in the design. A calibration circuitry can be used to further enhance the locking range. Measurement results show that the proposed ILFD functions as a divide-by-4 for an input frequency range of 1.8-3.2 GHz for an input power level as low as 23 dBm. The worst-case power consumption was approximately 2 mW from a 1.8 V power supply. The proposed ILFD can be used as a low-power prescaler for multi-band applications.     

Photo‐Thermo‐Mechanical Behaviour Under Quasi‐Static Tensile Conditions of a PMMA‐Core Optical Fibre

As the optical power transmitted by an optical fibre under tensile stress varies with strain, it can be used as a sensor for strain monitoring in structural elements. In the present work, quasi‐static tensile tests of step index polymer optical fibres (POF) with simultaneous measurement of surface temperature and optical power are described. Young's modulus, yield stress and tensile strength are derived from experimental tests. Morphological characterization of the POF fibres using scanning electron microscope images and differential calorimetry technique is performed. The contributions of both elastic and plastic strain components to the variation of temperature and optical power loss are also estimated. The evolution of the POF mechanical properties as well as that of temperature and optical power loss is explained in terms of the progressive relative movement and alignment of the molecular chains in the direction of the applied load. Strain, temperature and optical power loss are then correlated.     

A digital tachometer for high-temperature telemetry utilizing thermally uprated commercial electronic components

The high-temperature environment of an oil well requires reliable downhole instrumentation, typically based on simple and robust circuits, low power consumption, and smart measurement algorithms. In this paper, we present an electronic design and measurement methodology for a simple microcontroller-based digital tachometer, optimized for downhole spinner-flowmeter applications and multichannel telemetry. We have developed and experimentally evaluated an effective algorithm for direction-sensitive rotational speed measurement, which combines quadrature pulse decoding with the method of dependent count. The algorithm employs a temperature compensation technique, making it suitable for the high-temperature application of commercial-grade electronic parts. Our results confirm the functionality and reliable operation of the tachometer, targeted at high-temperature short-term oil-well logging applications.     

新型不锈钢材料的耐高温氧化及耐高温KCl蒸汽腐蚀性能

为缓解生物质电厂锅炉烟气侧的高温碱性环境腐蚀,对我国自主研发的4种新型不锈钢材料采用高温挂片试验(包括高温氧化试验和高温KCl蒸汽腐蚀试验)检测并绘制腐蚀动力学曲线;采用扫描电镜(SEM)、能谱仪(EDS)对试验后试片的形貌、结构、元素含量进行了分析,比较了4种新型不锈钢材料、传统TP316材料和高铬材料的耐高温氧化及耐高温KCl蒸汽腐蚀性能。结果表明:4种新型材料均表现出较好的耐腐蚀性能,明显优于传统的TP316材料和以往试验的高铬材料,当前更适用于生物质电厂锅炉烟气侧的高温碱性环境。     

Carbon incorporation in silicon-carbon films grown at different substrate temperatures

Hydrogenated microcrystalline silicon-carbon thin films have been deposited by plasma enhanced chemical vapour deposition technique at the substrate temperatures of 250 °C and 400 °C varying the radio frequency (RF) power in the 10-100 W range. The effects of substrate temperature and RF power on the structural, compositional, optical, and electrical properties have been investigated. The increase of substrate temperature or RF power leads to a decrease of crystallinity degree and an enhancement of carbon content. Optical absorption in the UV-visible region and electrical conductivity are affected in a different way by the RF power and substrate temperature variations. Silicon grain nucleation of films deposited at the temperature of 250 °C on commercial doped tin oxide substrate has been explored, for different RF power, by means of X-ray diffraction measurements.