电容式传感器在高炉喷吹煤粉质量流量测量中的应用

设计了一种工业用螺旋形状表面板电容式相浓度传感器，采用三维有限元方法对传感器结构进行优化设计，其检测场均匀性误差低于５％，有效地减小了相分布及流型变化对测量的影响；与电容式速度传感器组合成一体化装置，可用于在线测量气／固两相流质量流量。在现场与电子秤比对，整机精度误差小于５％。     

电容式传感器在高炉喷吹煤粉质量流量测量中的应用

设计了一种工业用螺旋形状表面板电容式相浓度传感器,采用三维有限元方法对传感器结构进行优化设计,其检测场均匀性误差低于5%,有效地减小了相分布及流型变化对测量的影响;与电容式速度传感器组合成一体化装置,可用于在线测量气/固两相流质量流量.在现场与电子秤比对,整机精度误差小于5%.     

DC和EMC铸造中熔融金属液面控制技术的新进展

文中介绍了金属液面控制技术中电容式传感器的进展，在铸锭铸造中的应用，传感器的感应如何与金属液面变化协调，金属回路感应与液面位置测量精度之间的关系，并介绍了先进的单回路数字式液面控制器。     

转鼓式切头飞剪剪切过程中速度衰减的最小化

以某厂引进的转鼓式切头飞剪为研究对象，依其剪切条件，对剪切过程中的速度衰减进行了讨论，提供了在剪切过程中使速度衰减最小的一种优化方法。实例分析表明，飞剪剪切不仅只取决于飞剪运动部分所释放的动能，而且电机适时补充能量决不可忽视。     

简讯

简讯我国首家传感器信息网开始运行该信息网由国家科委高技术计划自动化领域办公室主办，国科传感器研究开发中心和北京中方荣科技有限公司共同开发建成。该信息网采用会员制的方式，以国内外传感器及相关产品的研究、开发、咨询、生产、销售、管理及教学等部门为服务对象...     

基于CJ1H系列PLC在挤压机控制系统的设计与实现

本文设计了一种基于IPC-810A工控机系统和CJIH系列PLC组成上下位结构的挤压机床数控系统。重点叙述了以PLC为核心，应用磁致位移传感器、压力变送器和比例伺服调节阀等器件构成多闭环调控系统。分析了挤压速度的控制调整策略，得出模糊速度控制模型。     

LabView测试平台下图书馆用含锌金属传感器的设计与应用

图书馆的智能化监测与控制通过传感器技术参与完成。本文以图书馆用金属传感器为被控对象,利用Labview虚拟仪器技术分析传感器的静态特性和非线性误差,设计静态非线性温度补偿。在Labview环境下开发了用于含锌金属传感器信号测试的虚拟仪器。在Labview开发平台上进行实验研究,结合PID算法确保了动态控制的响应速度,提高了静态控制品质,为实际图书馆智能化管理系统的控制效果提供了依据。     

带双层桨的钨矿碱煮浸出槽内流场仿真分析

采用计算流体力学方法,研究了带JH型轴流搅拌桨、平直桨叶的浸出槽内的三维流场.以白钨矿和氢氧化钠溶液的混合液为模拟对象,运用多重参考系法(MRF)和标准k-ε湍流模型,模拟分析了双层搅拌桨以300 r/min的恒定转速在浸出槽内转动时产生的速度场、压力场和湍动能场,为浸出槽的结构优化设计提供参考依据.     

全燃高炉煤气锅炉炉内燃烧过程的数值模拟

以鞍钢股份公司220 t/h全燃高炉煤气锅炉为研究对象,利用CFD软件,对全燃高炉煤气锅炉炉内的燃烧过程进行模拟。得出锅炉炉内的速度场、温度场及NOx的排放量;并分析缩腰形炉膛及对冲布置的燃烧器对炉内燃烧过程的影响。模拟结果可为同类锅炉的优化设计、合理运行提供理论指导。     

冲击式预剥离液压特性分析

以大极板自动剥锌机预剥离液压系统为研究对象,分析了冲击式预剥离设备剥片过程的液压特性,建立了预剥离过程的仿真模型,并通过仿真分析,得到了蓄能器油压、冲击活塞速度及冲击功与活塞行程的关系,为液压系统的优化提供了理论支撑,为自动剥锌机预剥离设备的设计提供了理论参考和技术支持。     

Capacitive Micromachined Ultrasonic Transducers: Theory and Technology

Capacitive micromachined ultrasonic transducers (CMUTs), introduced about a decade ago, have been shown to be a good alternative to conventional piezoelectric transducers in various aspects, such as sensitivity, transduction efficiency, and bandwidth. In this paper, we discuss the principles of capacitive transducer operation that underlie these aspects. Many of the key features of capacitive ultrasonic transducers are enabled with micromachining technology. Micromachining allows us to miniaturize device dimensions and produce capacitive transducers that perform comparably to their piezoelectric counterparts. The fabrication process is described briefly, and the performance of the CMUT transducers is evaluated by demonstrating characterization results. It is shown that the transduction efficiency as defined by the electromechanical coupling coefficient can be close to unity with proper device design and operating voltage. It is also shown that CMUTs provide large bandwidth (123% fractional bandwidth) in immersion applications which translate into high temporal and axial resolution. Finally, the feasibility of using CMUTs is demonstrated by showing imaging examples in air and in immersion.     

A new biomedical mechanical impedance bridge

A system is described which measures directly the driving-point force, velocity and complex mechanical impedance of biological, non-biological and viscoelastic materials and structures. The system uses a single transducer and is capable of measuring the velocity responses to sinusoidal, linear, step and other forcing functions.     

基于六端网络法的压电超声换能器优化设计

压电超声换能器传统四端网络设计方法忽略了压电陶瓷晶堆内部的机电耦合过程，使用该方法所设计的压电超声换能器尺寸误差大，输出的超声振幅较小。为了提高压电超声换能器尺寸设计精度、增大换能器输出的超声振幅，本文将考虑压电陶瓷晶堆内部机电耦合作用的六端网络引入到压电超声换能器的设计中，分别采用四端网络法和六端网络法设计得到两个不同尺寸的压电超声换能器A和B，通过有限元方法对比分析了两个换能器的固有频率和输出振幅，并进一步通过实验验证了设计理论与仿真分析的有效性。研究结果表明，在相同激励电压下，采用六端网络法设计得到的压电超声换能器B输出的超声振幅是换能器A输出振幅的1.5倍，六端网络法设计压电超声换能器可以提高所设计换能器的振动性能。      

Tissue Doppler imaging and the quantification of myocardial function

Tissue Doppler imaging (TDI) has recently been introduced in clinical echocardiography. Most widely used are tissue velocity maps, in which the velocity of moving tissue is calculated relative to the transducer from the Doppler shift and displayed as colour-encoded velocity maps in either M-mode or two-dimensional image formats (Doppler velocity mode). This allows detection and quantification of dyssynergic areas of the myocardium. Additionally, the velocities may be studied with pulsed wave-tissue Doppler sampling (PW-TDS) which displays the velocity of a selected myocardial region versus time with high temporal resolution. Less often used, are tissue acceleration maps which display acceleration or velocity change of subsequent frames as different colours (Doppler acceleration mode). These maps may find application in clinical electrophysiology. Another TDI modality is tissue energy imaging, which is based on the integration of the power spectrum of the Doppler signals from the tissue. This technique provides maps of Doppler energy which are represented as colour brightness. Such maps offer potential for the study of myocardial perfusion. TDI modalities have promise to become clinically useful for quantifying myocardial function.     

Noninvasive ultrasonic carotid angiography: prospective validation by contrast arteriography

A technique for the beat-by-beat measurement of stroke volume is described. Aortic blood velocity signals are obtained from a catheter-mounted electromagnetic velocity transducer and analysed by a purpose-built analog computer. The stroke volume is computed by integration of each period of systolic forward flow using the velocity signal as its sole input. Automatic compensation of flowmeter drift is incorporated and inappropriate triggering of integration by diastolic artefact is prevented by applying both amplitude and duration criteria for the recognition of systolic forward flow. Early diastolic reverse flow is excluded from integration. The cardiac output, mean aortic flow per beat, and interbeat interval are also computed from the velocity signal. With aortic pressure as an additional input signal the mean arterial pressure per beat and systemic vascular resistance can be computed. The computer outputs are calibrated by a manual method. Preliminary studies comparing values for the cardiac output measured by this system and the direct Fick technique have indicated an excellent correlation between the two methods.     

MR measurement of time-dependent blood pressure variations

An MR imaging method for measuring intravascular pressure variations is introduced. The technique is based on estimates of vascular compliance and vessel distension, which are obtained from a correlation of spatial and temporal velocity derivatives and measurements of the velocity gradient in the direction of flow, respectively. The accuracy of the technique was determined in vitro through a comparison of MR and transducer pressure measurements obtained in distensible vessel phantoms undergoing pulsatile flow. Results indicated that a root-mean-square error of 4-12% can be expected in phantoms covering a physiological range of compliance. In vivo feasibility was demonstrated by thoracic aorta pressure measurements, which produced pressure waveforms with an expected shape and magnitude.     

Characterization of new murine monoclonal antibodies directed against glycophorins C and D

A multiple beam technique was utilized to obtain angle independent Doppler color images (AIDCI) using an ultrasonic scanner with a linear transducer. A quantitative study using steady flow models has been performed to evaluate the accuracy of this method in velocity measurements. The results show that the velocity amplitudes measured with this method correlated with those calculated from the measured flow rates (r = 0.95-0.98). The flow angles obtained with this method also correlated with those calculated from the coordinates of the tube image (r = 0.93-0.96). To improve the interpretation of the angle independent results, a method for visualizing two-dimensional flow fields is presented and compared with two existing methods.     

In vivo results with a new device for ultrasonic monitoring of pig skin cryosurgery: the echographic cryoprobe

One of the main difficulties encountered in cryosurgery is the uncertainty in the extent and depth of the tissue effectively treated during the freezing process. The objective of this study was to evaluate in vivo ultrasonic control of skin cryosurgery using a new echographic cryoprobe. An echographic cryoprobe, developed specifically for dermatology applications, combines a high-frequency (20 MHz) miniature ultrasonic transducer and a N2O-driven closed cryoprobe. Knowledge of the ultrasound velocity of frozen skin is a prerequisite for monitoring the iceball formation kinetics. Therefore, in a first study, we estimated the ultrasound velocity of frozen skin specimens. In a second step, the operation of the echographic cryoprobe was assessed, under in vivo conditions similar to those used in human therapeutics, on normal skin of three female "Large-White" pigs under anesthesia. The mean value of ultrasound velocity of frozen skin obtained by pooling the data from all the skin specimens included in this study was 2865 +/- 170 m per s. The average rates of growth (10(-2) mm per s) of the iceballs were found to be 12.2 +/- 1.0 (pig 1), 9.0 +/- 1.0 (pig 2), and 8.4 +/- 0.9 (pig 3). The echographic cryoprobe had a built-in high-frequency ultrasonic transducer that served two functions. It enabled in vivo real-time monitoring of depth penetration of the iceball and it gave important feedback to the operator or to the console relating to the rate of growth of the iceball. Automatic (i.e., operator-independent) detection of the echo signal from the freezing front and calculation of the depth penetration of the iceball was possible.     

Friction Coefficient Between Rolling Tube and Mandrel of Full Floating Mandrel Mill

 In the process of steel tube production, continuous tube rolling is the foremost forming procedure and the critical step that decides the dimension precision and the surface quality. In the actual production of the 140 mm full floating mandrel mill in Steel Tube Branch in Baosteel, steel T91 was chosen to be the typical sample, self made rolling force transducer and mandrel velocity testing equipment were used, and a series of comprehensive tests on rolling parameters including the rolling force and mandrel velocity were carried out. After the experiment, the friction state between rolling tube and mandrel was analyzed. The friction coefficient was calculated and the values of 0033-0074 in each mill were obtained. The friction coefficient increases obviously along the rolling direction.