A symmetrical stretching stage for electrical atomic force microscopy

We present a remotely-controlled device for sample stretching, designed for use with atomic force microscopy (AFM) and providing electrical connection to the sample. Such a device enables nanoscale investigation of electrical properties of thin gold films deposited on polydimethylsiloxane (PDMS) substrate as a function of the elongation of the structure. Stretching and releasing is remotely controlled with use of a dc actuator. Moreover, the sample is stretched symmetrically, which gives an opportunity to perform AFM scans in the same site without a time-consuming finding procedure. Electrical connections to the sample are also provided, enabling Kelvin probe force microscopy (KPFM) investigations. Additionally, we present results of AFM imaging using the stretching stage.     

Analysis of flow distribution from high-speed flow actuator using particle image velocimetry and digital speckle tomography

A variety of active flow control (AFC) methods are typically used in low-speed applications; however, the AFC techniques that are available for high-speed, supersonic applications are very limited. Under AFOSR (Air Force Research Laboratory) sponsorship, The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is investigating a device that is intended for high-speed flow control; it is called the SparkJet actuator, which manipulates high-speed flows without active mechanical components. To date, actuator characterization has included computational and experimental techniques including parametric studies and flow visualization techniques to investigate the operation of the SparkJet device under various conditions. This paper focuses on the experimental flow measurement techniques that have been implemented. The results will be used for validating prospective computational studies that investigate the detailed characteristics of the SparkJet’s discharge and cooling stages after an energy deposition pulse. Current efforts include the use of high- resolution particle image velocimetry (PIV) to quantify the quiescent air operation of a single SparkJet pulse. However, the proper seeding of the SparkJet cavity continues to be challenging and has led to the use of digital speckle tomography (DST) to measure the temperature distribution in the core of the SparkJet plume. In this study, improved PIV techniques were used to acquire a higher-resolution image of the SparkJet-entrained flow. These PIV results show that the peak velocity in the entrained flow is around 53 m/s and the plume is sustained for 75–100 μs. Additionally, the DST data show a peak temperature of 1616.3 K at 75 μs and provide supporting information for interpreting the PIV data. These results are intended to calibrate and build confidence in a computational model.     

Development of a micro cell compression stimulator for evaluating real-time cellular responses

This paper presents a micro cell compression stimulator for evaluating real-time cellular responses to compression stimuli. The device was produced by a micro three-dimensional structure fabrication process using multiple exposures to the photoresist. The device consists of a pressure inlet port, cell inlet ports, a gasket, microchannels, cell culture chambers, and a diaphragm on the culture chamber for applying compressive pressure to cells. Compression stimuli applied to the cells can be controlled by regulating the expansion of the diaphragm via a pressure control. The device permits the observation of cellular responses to compressive pressure in real time because it is made of transparent materials and stimulates the cells without deforming the cell culture surface, when observed by optical microscopy. We demonstrated the validity of the fabrication process, evaluated the performance of the fabricated device, and compared the experimental results with the FEM structural analysis results. We found through operational testing that the diaphragm was deformed quickly by applying negative/positive pressure and that the diaphragm displacement became larger with increasing applied pressure. These results indicate that this device can be used to control the intensity and the cell stimulus profile by regulating the applied pressure. In all cases, the cellular deformation during compression stimulus was successfully observed in real time using an optical microscope. The device is expected to facilitate the control of stem cell differentiation and the clarification of cellular mechanoreceptor mechanisms and signal transduction pathways.     

Bifurcation Analysis of an Electrostatically Actuated Nano-Beam Based on Modified Couple Stress Theory

In this paper, the nonlinear size-dependent static and dynamic behavior of an electrostatically actuated nano-beam is investigated. A fully clamped nano-beam is considered for the modeling of the deformable electrode of the NEMS. The governing differential equation of the motion is derived using Hamiltonian principle based on couple stress theory; a non-classical theory for considering length scale effects. The nonlinear partial differential equation of the motion is discretized to a nonlinear Duffing type ODE’s using Galerkin method. Static and dynamic pull-in instabilities obtained by both classical theory and MCST are compared. At the second stage of analysis, shooting technique is utilized to obtain the frequency response curve, and to capture the periodic solutions of the motion; the stability of the periodic solutions are gained by Floquet theory. The nonlinear dynamic behavior of the deformable electrode due to the AC harmonic accompanied with size dependency is investigated.     

A demultiplexing unit for separating incident and reflected nano- and picosecond pulse signals

A device on the basis of a double directional bridge for separating ultrawideband pulse signals that are incident on and reflected from an arbitrary load is described. The experimental results from studies of the device using picosecond (40 ps) and nanosecond (10 ns) electrical pulses are presented. A test pulse that feeds the input port comes to a device under test (DUT) with an attenuation of 5 dB. The device separates the resulting incident and reflected pulses that arrive at different ports. The isolation between the ports of the incident and reflected pulses is at least 20 dB in the operating-frequency range from 300 kHz to 16 GHz.     

Fast on-wafer electrical, mechanical, and electromechanical characterization of piezoresistive cantilever force sensors

Validation of a technological process requires an intensive characterization of the performance of the resulting devices, circuits, or systems. The technology for the fabrication of micro and nanoelectromechanical systems (MEMS and NEMS) is evolving rapidly, with new kind of device concepts for applications like sensing or harvesting are being proposed and demonstrated. However, the characterization tools and methods for these new devices are still not fully developed. Here, we present an on-wafer, highly precise, and rapid characterization method to measure the mechanical, electrical, and electromechanical properties of piezoresistive cantilevers. The setup is based on a combination of probe-card and atomic force microscopy technology, it allows accessing many devices across a wafer and it can be applied to a broad range of MEMS and NEMS. Using this setup we have characterized the performance of multiple submicron thick piezoresistive cantilever force sensors. For the best design we have obtained a force sensitivity Re(F) = 158μV/nN, a noise of 5.8 μV (1 Hz-1 kHz) and a minimum detectable force of 37 pN with a relative standard deviation of σ(r) ≈ 8%. This small value of σ(r), together with a high fabrication yield >95%, validates our fabrication technology. These devices are intended to be used as bio-molecular detectors for the measurement of intermolecular forces between ligand and receptor molecule pairs.     

岸边集装箱起重机夹板类型平衡装置抗阻性能的实验研究

采用实验手段,对岸边集装箱起重机、卸船机及装卸桥的臂架俯仰系统夹板类平衡装置的摩擦阻力系数及影响因素进行定性、定量研究,从而为该系统的设计、施工、安装、使用维护等要素提供实验依据,进而全面提升港机产品的制造技术。     

微/纳机电系统

微机电系统（MEMS）和纳机电系统（NEMS）是微米／纳米技术的重要组成部分。MEMS已在产业化道路上发展，NEMS还处于基础研究阶段，分析了微／纳机电系统的发展特点，简要地介绍了典型的MEMS和NEMS器件及系统后，讨论了MEMS和NEMS发展中的几个问题以及它们的发展前景。     

A device for measuring the angular distribution of the output radiation of optical fibers

The characteristics of a device developed for measuring the angular distribution of the intensity of the output radiation of optical fibers in the far field are described. The devices angular translation stage is controlled through a standard parallel port of a personal computer, and the experimental data are acquired and digitized using a standard sound card. The dynamic range of measurements is >50 dB. Examples of measurements performed with this device for single-mode optical fibers of several types are presented. Good agreement between the calculated and experimental data is demonstrated. The effect of the dynamic range of measurements in the far field on the accuracy of calculating the mode field distribution was investigated.Translated from Pribory i Tekhnika Eksperimenta, No. 1, 2005, pp. 112–118.Original Russian Text Copyright © 2004 by Grekov, Vasilev, Korolev, Bozhkov, Medvedkov, Senatorov.     

An adaptive control of an autonomous guided vehicle system using cell-mediated immune algorithm controller and vision sensor

In this paper, we proposed an adaptive control method which is named CMIA (cell-mediated immune algorithm) controller with PID scheme. It is based on specific immune response of the biological immune system which is the cell-mediated immune response. It is also applied for the autonomous guided vehicle (AGV) system which is manufactured in this paper. The AGV is used for the port automation to carry container without human and to overcome uncertainty and nonlinearity because of running in the outdoor. To verify the performance of the proposed CMIA controller, some experiments for the AGV system are performed. Finally, the experimental results for the control of steering and speed of an AGV system illustrate the effectiveness of the proposed control scheme. These results for the proposed method also show that it has better performance than other conventional controller design methods. Key Words: Port Automation, Autonomous Guided Vehicle (AGV), Adaptive Control, Cell-Mediated Immune Algorithm (CMIA) Controller, Vision Sensor, Neural Network Identifier (NNI)     

Correlated fluorescence lifetime and spectral measurements in living cells

Studies of proteins' interaction in cells by FRET can take benefit from two important photo-physical properties describing fluorescent proteins: fluorescence emission spectrum and fluorescence lifetime. These properties provide specific and complementary information about the tagged proteins and their environment. However, none of them taken individually can completely quantify the involved fluorophore characteristics due to their multiparametric dependency with molecular environment, experimental conditions, and interpretation complexity. A solution to get a better understanding of the biological process implied at the cellular level is to combine the spectral and temporal fluorescence data acquired simultaneously at every cell region under investigation. We present the SLiM-SPRC160, an original temporal/spectral acquisition system for simultaneous lifetime measurements in 16 spectral channels directly attached to the descanned port of a confocal microscope with two-photon excitation. It features improved light throughput, enabling low-level excitation and minimum invasivity in living cells studies. To guarantee a fairly good level of accuracy and reproducibility in the measurements of fluorescence lifetime and spectra on living cells, we propose a rigorous protocol for running experiments with this new equipment that preserves cell viability. The usefulness of SLiM approach for the precise determination of overlapping fluorophores is illustrated with the study of known solutions of rhodamine. Then, we describe reliable FRET experiments in imaging mode realized in living cells using this protocol. We also demonstrate the benefit of localized fluorescence spectrum-lifetime acquisitions for the dynamic study of fluorescent proteins. proteins.     

Sliding mode control with varying boundary layers for an electro-hydraulic position servo system

In this study, a new sliding mode control with varying boundary layers is proposed to improve the tracking performance of a nonlinear electro-hydraulic position servo system, which can be found in many manufacturing devices. The key feature of the proposed control scheme is the use of varying boundary layers instead of fixed boundary layers, which are usually employed in conventional sliding mode control. The validity of the proposed control scheme is verified through practical testing on an experimental electro-hydraulic positioning device. In the cases of step and sinusoidal command inputs, the experimental results strongly suggest that the proposed control scheme is capable of improving the tracking precision without causing any chattering. In addition, the new control scheme seems to be very robust against various set point conditions .     

采用可编程器件实现I2C接口

采用硬件描述语言AHDL在可编程器件上实现I^2C总线主控制器模式接口，可供没有I^2C总线接口的智能控制器接入I^2C总线，以简化系统软、硬件设计的难度，并具有接口简单、可以直接接入高速并行总线、资源消耗小等特点。     

Towards a novel tensile elastometer for soft tissue

A device designed to determine the tensile properties of soft tissue is proposed for use within the surgical environment. Two pins indent the surface of a bulk of soft tissue and are separated laterally. Using an approximation, the measured load and displacement are mapped to the uniaxial stress and strain of a central volume of material. A correction factor is introduced that depends on geometric factors only for Mooney–Rivlin materials subject to strains of up to 15%, if edge effects are not significant. It is the intention of this study and subsequent studies to design the instrument such that edge effects are minimised. Numerical analysis is employed to test the limits of both the device and the model for Mooney–Rivlin materials. Further analysis is required to determine viability for soft tissue that can display significant anisotropy, material non-homogeneities and highly nonlinear elastic responses. Some initial results towards this end are presented. The method is demonstrated with the use of a prototype device, employing common elastomers to model the soft tissue. An assessment of the accuracy of the prototype and limitations on the use of the device are inferred from the experimental and numerical studies. The modulus of the test materials was subsequently measured to an accuracy of 4% with a spread of 6.5% (using a 95% confidence interval).     

温控箱远程监控系统软件设计

某公司设备分散分布在不同的区域,距离较远,环境干扰严重,且设备的控制系统种类繁多。本系统通过读写各类温控箱的可编程控制器,实现对各类温控箱运行状态和数据的远程集中监控与记录。要求可靠地实现设备的联网监控,且不能影响原系统的运行。介绍了以C#作为编程语言的系统软件设计,采用串口通信进行数据传输并保存在数据库中,实现了基本功能,且界面友好,运行稳定。     

Mechanical characterization of micro/nanoscale structures for MEMS/NEMS applications using nanoindentation techniques

Mechanical properties of micro/nanoscale structures are needed to design reliable micro/nanoelectromechanical systems (MEMS/NEMS). Micro/nanomechanical characterization of bulk materials of undoped single-crystal silicon and thin films of undoped polysilicon, SiO(2), SiC, Ni-P, and Au have been carried out. Hardness, elastic modulus and scratch resistance of these materials were measured by nanoindentation and microscratching using a nanoindenter. Fracture toughness was measured by indentation using a Vickers indenter. Bending tests were performed on the nanoscale silicon beams, microscale Ni-P and Au beams using a depth-sensing nanoindenter. It is found that the SiC film exhibits higher hardness, elastic modulus and scratch resistance as compared to other materials. In the bending tests, the nanoscale Si beams failed in a brittle manner with a flat fracture surface. The notched Ni-P beam showed linear deformation behavior followed by abrupt failure. The Au beam showed elastic-plastic deformation behavior. FEM simulation can well predict the stress distribution in the beams studied. The nanoindentation, scratch and bending tests used in this study can be satisfactorily used to evaluate the mechanical properties of micro/nanoscale structures for use in MEMS/NEMS.     

Numerical simulation for the behavior of superelastic shape memory alloys

Superelastic shape memory alloys (SMAs) are unique metallic materials that undergo substantial plastic deformations and recover their original conditions when stresses are only removed without any heat treatment. SMAs have currently become prevalent for application in structural engineering because this superelastic property contributes to entire construction system by mitigating the problem of permanent deformation. Notwithstanding many structural advantages, there exist relatively few investigations on the numerical modeling of these smart materials, which had been mostly used for nonlinear analyses. For this reason, this study mainly focuses on a one-dimensional (1D) constitutive model able to simulate the inherent behavior of superelastic SMAs, taking into account phase transformation between austenite and martensite. After discussing a possible approach for the solution scheme, numerical simulation results are compared to experimental data obtained from pull-out tests that are performed on SMA bars in order to validate the adequacy for the 1D constitutive material model presented. Furthermore, the user material model based on the solution algorithm of reproducing this superelastic behavior is applied to the structural analysis with a view to assure adequacy in practical use.     

虚拟PLC仿真实验平台的设计

为解决目前PLC仿真实验平台在无PLC硬件条件下无法进行PLC实验及远程资源共享的问题,提出了一种完全虚拟条件下的PLC仿真实验平台。该实验平台由PLC仿真软件GX Simulator、工业组态软件组态王和虚拟串口软件VSPD组成。PLC仿真软件虚拟实际的PLC,工业组态软件模拟实际的控制对象,虚拟串口实现虚拟PLC和组态王的通信,并可以通过Web发布将实验平台与各个用户终端相连,实现实验资源的远程共享。该实验平台充分利用现有计算机和网络资源,满足了学生自主学习和自我学习的要求,是一种先进的PLC实验教学系统。     

喷射装置导管对大缸径气体燃料发动机缸内混合效果的影响

在喷射装置出口加装导管,将燃气分别导向大缸径多点电喷气体燃料发动机的螺旋进气道和切向进气道,建立了联合喷射装置内部流动区域的发动机瞬态CFD计算模型,分析了导管位置对缸内掺混过程的影响。研究结果表明：对于该切向气道、螺旋气道的组合进气道,进气冲程在缸内靠近缸盖截面上产生了干涉涡流,对于螺旋气道喷射方案,燃气向气缸中心靠近,压缩末了时刻燃气集中在缸盖附近;而对于切向气道喷射方案,燃气冲向活塞顶,压缩末了时刻燃气集中在活塞顶附近。点火时刻的混合效果从优到劣依次为螺旋气道喷射方案、无导管喷射方案、切向气道喷射方案。     

Development of the mennen 3 peripro fixation plate for the treatment of periprosthetic fractures of the femur

The Mennen femur plate is an internal fixation device used for the management of femoral perisprosthetic fractures, usually after total hip replacement surgery. The implant uses a number of curved prongs that embrace the fractured bone around its circumference without interfering with the stem of the prosthesis. Although the device has been used with considerable clinical success since its first introduction, a number of negative clinical results have been reported in the literature. The failure modes of the device are described and an evaluation of its performance is briefly presented. Based on this assessment as well as comments in the open literature, modifications in the design of the device have been implemented. The new Mennen 3 PeriPro plate is presented, with all the necessary data for a coherent explanation of its improved characteristics as defined using numerical simulations and experimental tests. The new device has all the beneficial features of the previous plate with improved structural performance and fatigue life and new sculpted formation of the prongs, providing a simple implantation technique with maximum gripping and minimum effort from the surgeon. The unique mode of fixation has been further improved, providing ample anchorage on the fracture bone without compromising its biomechanical integrity. By combining the device with a cable system, the spectrum of applications will be further expanded, enabling the surgeon to treat a broader range of fracture patterns.