自动控温单轴蠕变仪研制

青藏铁路将要穿越的多年冻土大多属于高温冻土,其中近一半为高含冰量冻土。由于实验条件限制,人们对高温高含冰量冻土认识非常有限。对于青藏铁路沉降变形的预测却在一定程度上依赖于这部分力学参数确定。因此,研制适合高温冻土蠕变实验研究设备非常必要。该仪器利用现有冰箱制冷技术,外加一套控温技术和数据采集系统的技术。此设备设计新颖、控温精度高、加力系统稳定、节约能源、环保、移动方便等特点。很有实用价值,设备制冷控温部分和数据采集部分还可单独分开使用。     

CHY-1型便携式测氦仪的研制和应用

研制成功一种超小型便携式质谱计.仪器能够在野外现场测定样品中的氦气和氢气浓度及二者的比值,已经用于首都圈(河北省、天津市和北京市)地区20处地下流体流动观测点地下水、断层气样品的测定工作.测定数据按照测定点的经纬度、测定点名称、测定号、测定日期和时间保存.利用计算机将数据从仪器中取出进行编辑与处理.各种供电采用了DC-DC的模块,简化了由变压器整流滤波的供电方式.仪器具有灵敏度高,操作简便,稳定性好、数字显示、测定过程由单片机控制及便于携带的特点.     

便携式阻抗测量仪的研制与应用

本研究建立涂层性能快速测试方法并研制相关测试仪器。该仪器由一台便携式的交流阻抗测试仪及相关软件构成,可作为一般的交流阻抗测试仪进行全频率区间的交流阻抗测试,用于研究涂层的保护性能和失效过程;也可在工程应用现场对涂层性能进行快速测试,实现对涂层服役性能的快速评价。     

Development of eddy current microscopy for high resolution electrical conductivity imaging using atomic force microscopy

We present a high resolution electrical conductivity imaging technique based on the principles of eddy current and atomic force microscopy (AFM). An electromagnetic coil is used to generate eddy currents in an electrically conducting material. The eddy currents generated in the conducting sample are detected and measured with a magnetic tip attached to a flexible cantilever of an AFM. The eddy current generation and its interaction with the magnetic tip cantilever are theoretically modeled using monopole approximation. The model is used to estimate the eddy current force between the magnetic tip and the electrically conducting sample. The theoretical model is also used to choose a magnetic tip-cantilever system with appropriate magnetic field and spring constant to facilitate the design of a high resolution electrical conductivity imaging system. The force between the tip and the sample due to eddy currents is measured as a function of the separation distance and compared to the model in a single crystal copper. Images of electrical conductivity variations in a polycrystalline dual phase titanium alloy (Ti-6Al-4V) sample are obtained by scanning the magnetic tip-cantilever held at a standoff distance from the sample surface. The contrast in the image is explained based on the electrical conductivity and eddy current force between the magnetic tip and the sample. The spatial resolution of the eddy current imaging system is determined by imaging carbon nanofibers in a polymer matrix. The advantages, limitations, and applications of the technique are discussed.     

Tip bluntness transition measured with atomic force microscopy and the effect on hardness variation with depth in silicon dioxide nanoindentation

Depth-sensing indentation measurements of surfaces and structures with indentation depths less than 100 nm necessitate the use of accurate area functions for correct property evaluation. Here, the effect of a blunt nanoindenter tip geometry is characterized using atomic force microscopy to measure the direct tip geometry and modeled by a power law profile shape. Direct measurement of tip geometry is a method to observe changes in the tip curvature and transition from the blunt tip region to an ideal tip geometry. The tip shape, curvature, and transition to ideal geometry is found to correspond with the increase in hardness observed experimentally in SiO2 using a self-similar contact model. For a Berkovich indenter, tip bluntness was found to have a power law degree of 1.5 near the tip apex with a continuously varying degree of bluntness until an ideal pyramidal shape was reached at a depth of 160 nm.     

手腕动力参数测试系统的研制

介绍了一种用于手腕动力参数测试的系统，概述了系统的硬件结构、工作原理及其软件设计，该系统为医学研究提供了良好的实验平台。     

一种风速模拟仪器的研制

各种测风传感器在出厂前,都要根据标准在测量范围内进行风速参数测试,以检验是否超差.通常采用模拟风速,然后将传感器的实测值和模拟值进行比对的方法.如何获得模拟风速,并能将模拟值与实际值比对,则是各种测风传感器风速试验所面临的关键问题.现根据螺旋桨式测风传感器每一定值风速对应风速轴一固定转速值的自身特点,设计研发了一种风速模拟仪器.该仪器是专为螺旋桨式测风传感器的风速测试检验所研制开发的一种装置.在做测试检验时,能够模拟风速和测得实际风速值,并能够实时显示.该仪器为智能化仪器,提高了检测效率,使风速测试检验具有实效性,比对性.且结构简洁、造价低、实用性强.     

煤燃烧特性综合测试仪的研制

介绍了自制的煤燃烧特性综合测试议的测量原理、仪器组成及测量方法。该测试仪由燃烧炉、温度控制器、气氛气动控制系统、热天平、气体测量仪、微计算机系统组成。采用稳态测量方法测量煤的着火温度、燃尽时间及工业分析值 ,用计算机进行数据处理和分析 ,对煤质作出基本评价 ,为合理用煤提供科学依据。     

智能型电磁无损检测仪的研制

根据钢铁材质特性参数与材料本身的某些物理量(例如磁导率)之间所具有的对应关系,设计了一种基于系统级单片机(C8051F020)的智能型钢铁材质电磁无损检测仪器,对仪器的检测原理以及仪器的软硬件设计进行了详细说明.实践表明,该仪器具有检测速度快,精度高的特点.     

Development of a microlateral force sensor and its evaluation using lateral force microscopy

A microlateral force sensor (MLFS) was developed and evaluated using atomic force microscopy (AFM). The sensor was attached to a sensing table supported by a suspension system. The lateral motion of the sensing table was activated by a comb actuator. The driving voltage to the comb actuator was controlled to maintain a constant position of the sensing table by detecting the tunneling current at a detector, which consisted of two electrodes where the bias voltage was applied. An AFM was used to apply a lateral force to the sensing table of the sensor. When the probe of a cantilever was pressed against the sensing table and a raster scanning was conducted, the driving voltage of the comb actuator changed to compensate the friction force between the probe and sensing table. AFM measurements of an asperity array on the sensing table were conducted, and a lateral force microscopy image (LFM) was obtained from the change in driving voltage. The image by MLFS was very similar to the LFM image that was conventionally obtained from torsion of the cantilever. The LFM image strongly correlated with the gradient image calculated from the AFM topographic image. The force sensitivity of the MLFS was determined by comparing the LFM image obtained by using the MLFS with the tangential force derived from the gradient of the AFM image.     

简易仪表测力器的研制

为保证仪表使用功能的稳定,制做了简易仪表测力器,快捷准确,满足了检定仪表测力以及测力变化的需要。     

新型电化学原子力显微镜的研制

电化学原子力显微镜将电化学分析技术与原子力显微镜结合起来,能对生物传感器,新型电池和电腐蚀进行原位电化学扫描探针显微测量分析。为了实现电化学与扫描探针功能的系统集成,在控制电路设计中采用现场可编程门阵列,提高了系统的可靠性。电化学控制箱与原子力显微镜的头部紧密集成,保证微弱信号不受干扰,并具有多种电化学工作模式。系统具有稳定性好,重复性高,抗干扰能力强等优点。     

Calibration of lateral force measurements in atomic force microscopy with a piezoresistive force sensor

We present here a method to calibrate the lateral force in the atomic force microscope. This method makes use of an accurately calibrated force sensor composed of a tipless piezoresistive cantilever and corresponding signal amplifying and processing electronics. Two ways of force loading with different loading points were compared by scanning the top and side edges of the piezoresistive cantilever. Conversion factors between the lateral force and photodiode signal using three types of atomic force microscope cantilevers with rectangular geometries (normal spring constants from 0.092 to 1.24 N/m and lateral stiffness from 10.34 to 101.06 N/m) were measured in experiments using the proposed method. When used properly, this method calibrates the conversion factors that are accurate to +/-12.4% or better. This standard has less error than the commonly used method based on the cantilever's beam mechanics. Methods such of this allow accurate and direct conversion between lateral forces and photodiode signals without any knowledge of the cantilevers and the laser measuring system.     

Development of a three-component dynamometer to measure turning force

This work is focused on the design, construction and testing of a strain gauge dynamometer devised to measure the three components of the turning force. For this purpose, an elastic element sensitive to torsion and flexion was developed. The effect of the cutting parameters (cutting speed, feed rate and depth of cut) on the force components was investigated. Additionally, the performance of the dynamometer was compared with a commercial piezoelectric device. The results indicated that the three components of the turning force decrease slightly as cutting speed was elevated and increase linearly with feed rate and depth of cut. Furthermore, the analysis of variance indicated that the three components are not significantly affected by cutting speed; however, they are significantly affected by feed rate and depth of cut. The comparative tests indicated that the strain gauge dynamometer presented a satisfactory performance, providing closer values to the piezoelectric dynamometer at higher depth of cut values.     

Development of custom-made RF coil for magnetic resonance velocimeter with a high spatial resolution

Magnetic resonance velocimetry (MRV) is a versatile flow visualization technique that is used to measure three-component velocity vectors in a 3D space. However, the spatial resolution of MRV is relatively poor in comparison with optical flow visualization techniques, thereby limiting its applicability to small-scale flows and wall shear stress (WSS) estimation. Thus, we built a solenoid RF coil and evaluated its performance in terms of spatial resolution improvement by measuring the laminar flow in a circular tubing. The coil was developed for a 4.7 Tesla MRI system and for tightly wrapping a flow tubing with an inner diameter of 2 mm. The custom-made RF coil could precisely capture the velocity vectors in a voxel that was 11 times smaller than a commercial coil at the same SNR. Therefore, the WSS errors estimated using the custom-made and commercial coils were 8.5 % and 42.3 %, respectively.

     

Direct measurement of tapping force with a cantilever deflection force sensor

An experimental set up dedicated to the measurement of atomic force microscope tapping force was developed. In the set-up, a standard TappingMode™ probe cantilever was used to tap another cantilever equipped with its own low noise and high sensitivity deflection detection system for force measurement. The amplitude and phase change of the tapping lever as well as the deflection of the sensing lever were simultaneously recorded as a function of tip/surface separation. Since the deflection of the sensing cantilever reflects the average force over one interaction cycle, we measured the total average force quantitatively after calibrating the spring constant and deflection sensitivity of the sensing lever. Considerable effort was made to achieve the same force curve in the tapping force measurement as occur during imaging of conventional samples such that the detected tapping force reflects the same interaction of the imaging process.     

Development of a precision indentation and scratching system with a tool force and displacement control module

This article presents a tip-based micropatterning system with a precision device for measuring the machine force and the tool path. The machine force is obtained by a tool control module with a leaf spring and a capacitive displacement sensor. It is controlled to provide a force that ranges from 80 microN to 8 N. The force sensing unit, which is part of the module, is mounted on a PZT (PbZrTi) driven in-feed motion stage with a resolution of 1 nm. The work piece is set on an X-Y motion stage, and the position can be controlled with a tool path accuracy of 5 nm. Micropatterning and precision indentation experiments were performed, while the machined surfaces were examined by atomic force microscopy. From these results, the feasibility of the system for precise force-displacement control was verified for application in tip-based precision machining.     

Development and metrological characterization of a precision force transducer for static force measurement related applications

The present paper discusses design and development of a force transducer of octagonal ring shape, which is a modified version of ring shaped force transducer. Nominal capacity of the force transducer designed and developed is 25 kN. This force transducer has been investigated for its utilization as force transfer standard for static force measurement and related applications. This force transducer is studied using dial gauge and strain gauges for its metrological characterization according to the calibration procedure based on standard ISO 376:2011/IS 4169:1988 (reaffirmed 2003) and is found to have good metrological results as compared to the existing ring shaped force transducers.