Comparison of characteristics of fluorine doped zinc and gallium tin oxide composite thin films deposited on stainless steel 316 bipolar plate by electron cyclotron resonance-metal organic chemical vapor deposition for proton exchange membrane fuel cells

In order to replace the brittle graphite bipolar plates currently used for the PEMFC stack, coated SUS 316 was employed. As a metallic bipolar plate, coated SUS 316 can provide higher mechanical strength, better durability to shocks and vibration, less permeability, improved thermal and bulk electrical conductivity, as well as being thinner and lighter. To enhance the interfacial contact resistance and corrosion resistance of SUS 316, the deposition of GTO:F and ZTO:F composite films was carried out by ECR-MOCVD. The surface morphology of the films consisted of tiny elliptically shaped grains with a thickness of 1 microm. The corrosion current for GTO:F was 0.13 Acm(-2) which was much lower than that of bare SUS 316 (50.16 Acm(-2)). The GTO:F coated film had the smallest corrosion current due to the formation of a tight surface morphology with very few pin-holes. The GTO:F coated film exhibited the highest cell voltage and power density due to its lower ICR values.     

Depth Transfer by an Imaging System

In many applications such as three-dimensional (3-D) data acquisition, the scanning of 3-D objects or 3-D display, it is necessary to understand how an imaging system can be used to obtain information on the structure of an object in the direction perpendicular to the image plane, i.e. depth information. In certain cases the formation of a 3-D image can be described by a theory based on optical transfer functions (OTF): the image intensity distribution is given by the 3-D convolution of the object and a 3-D point spread function (PSF); equivalently, in 3-D Fourier space the image spectrum is the product of the object spectrum and a 3-D OTF. This paper investigates the 3-D PSFs and OTFs that are associated with different pupil functions of the imaging system.     

Three-dimensional measurement of ice crystals in frozen beef with a micro-slicer image processing system

A novel technique has been developed for measuring the three-dimensional (3-D) structure and distribution of ice crystals formed in frozen beef by using a micro-slicer image processing system (MSIPS). The system has functions to reconstruct the 3-D image based on the image data of exposed cross-sections obtained by multi-slicing of a frozen sample with the minimum thickness of 1 μm and to display the internal structure as well as an arbitrary cross-section of the sample choosing observation angles. The size and distribution of ice crystals can be determined from the 2-D quantitative information, such as the periphery and area of the crystals. The effects of freezing conditions on the morphology and distribution of the ice crystals were demonstrated quantitatively from the observations of raw beef stained by fluorescent indicator. For the samples frozen at −15 °C, the network structure of ice crystals were observed mainly at intercellular space, having approximately 100 μm in cross-sectional size, while that prepared at −120 °C showed the spherical crystals of 10–20 μm in diameter within the cells. The 3-D image of the sample demonstrated that the growth of ice columns was restricted by the intrinsic structure of muscle fibers. The proposed method provided a new tool to investigate the effects of freezing conditions on the size, morphology and distribution of ice crystals.     

Optoelectronic wavelet processors based on Smartt interferometry

Optoelectronic wavelet-processor implementations based on Smartt interferometry are described for both one-dimensional (1-D) and two-dimensional (2-D) wavelet transforms. The 1-D processor study focuses on the processor's capability to perform the wavelet transform when the wavelets are defined in the time domain. The experimental results indicate that the system preserves all the phase information of the selected mother wavelets and thus delivers the true wavelet transform. The 2-D version of the processor is designed for the implementation of the complex wavelet transform. This processor will be valuable for applications, such as image coding-decoding, for which the preservation of phase information is necessary. A pair of prototype processors that incorporates.the 1-D and the 2-D systems has been built and tested to mechanical vibrations. High-quality reconstructed images were also obtained from the experimental data. The proposed systems have great potential for many practical applications.     

基于Solid Edge的尺寸链公差分配研究

Solid Edge是易学、高效、易用的机械计算机辅助设计系统，支持从三维到二维工程图的自动生成。但尺寸链的计算与分配仍需要手工进行，用VC 在Solid Edge的基础上进行开发，编制了尺寸链计算与分配模块，实现了计算机完成尺寸链的计算与分配，并且在二维工程图中自动标注尺寸公差，为基于尺寸链的加工精度分配提供依据，增强了Solid Edge机械产品的设计能力。     

Two-Dimensional Image Transmission Based on the Ultrafast Optical Data Format Conversion between a Temporal Signal and a Two-Dimensional Spatial Signal

We have experimentally demonstrated a two-dimensional (2-D) image transmission based on the ultrafast optical data format conversion between a temporal signal and a spatial signal with an ultrashort optical pulse. In the proposed system we adopt a spectral holography technique to transmit a one-dimensional (1-D) spatial signal and use a spatial-domain time-frequency transform to realize a transform between 1-D and 2-D spatial signals. By use of these techniques, a low-optical-loss transmission system can be constructed. To demonstrate a 2-D image transmission with this technique, we achieved experimentally transmission of the alphabet letter T as a 3 x 3 pixel 2-D spatial image.     

Three-dimensional photoacoustic imaging using a two-dimensional CMUT array

In this paper, we describe using a 2-D array of capacitive micromachined ultrasonic transducers (CMUTs) to perform 3-D photoacoustic and acoustic imaging. A tunable optical parametric oscillator laser system that generates nanosecond laser pulses was used to induce the photoacoustic signals. To demonstrate the feasibility of the system, 2 different phantoms were imaged. The first phantom consisted of alternating black and transparent fishing lines of 180 μm and 150 μm diameter, respectively. The second phantom comprised polyethylene tubes, embedded in chicken breast tissue, filled with liquids such as the dye indocyanine green, pig blood, and a mixture of the 2. The tubes were embedded at a depth of 0.8 cm inside the tissue and were at an overall distance of 1.8 cm from the CMUT array. Two-dimensional cross-sectional slices and 3-D volume rendered images of pulse-echo data as well as photoacoustic data are presented. The profile and beamwidths of the fishing line are analyzed and compared with a numerical simulation carried out using the Field II ultrasound simulation software. We investigated using a large aperture (64 x 64 element array) to perform photoacoustic and acoustic imaging by mechanically scanning a smaller CMUT array (16 x 16 elements). Two-dimensional transducer arrays overcome many of the limitations of a mechanically scanned system and enable volumetric imaging. Advantages of CMUT technology for photoacoustic imaging include the ease of integration with electronics, ability to fabricate large, fully populated 2-D arrays with arbitrary geometries, wide-bandwidth arrays and high-frequency arrays. A CMUT based photoacoustic system is proposed as a viable alternative to a piezoelectric transducer based photoacoustic systems.     

Static response and free vibration of two-dimensional functionally graded metal/ceramic open cylindrical shells under various boundary conditions

The free vibration and static response of a two-dimensional functionally graded (2-D FGM) metal/ceramic open cylindrical shell are analyzed using 2-D generalized differential quadrature method. The open cylindrical shell is assumed to be simply supported at one pair of opposite edges and arbitrary boundary conditions at the other edges such that trigonometric functions expansion can be used to satisfy the boundary conditions precisely at simply supported edges. This paper presents a novel 2-D power-law distribution for ceramic volume fraction of 2-D FGM that gives designers a powerful tool for flexible designing of structures under multifunctional requirements. Various material profiles in two radial and axial directions are illustrated using the 2-D power-law distribution. The effective material properties at a point are determined in terms of the local volume fractions and the material properties by the Mori–Tanaka scheme. The 2-D generalized differential quadrature method as an efficient and accurate numerical tool is used to discretize the governing equations and to implement the boundary conditions. The convergence of the method is demonstrated, and to validate the results, comparisons are made with the available solutions for FGM cylindrical shells. The interesting results indicate that a graded ceramic volume fraction in two directions has a higher capability to reduce the mechanical stresses and natural frequency than conventional 1-D FGM. The achieved results confirm that natural frequency and mechanical stress distribution can be modified to a required manner by selecting an appropriate volume fraction profile in two directions.     

Effects of sample dimension and dye distribution characteristics in absorption microspectroscopy

Models and the relevant equations giving optical absorbance of an analyte (i.e., dye) confined in a small volume with different shapes and sizes (sample dimension, D) are given, and factors governing absorbance are discussed. Dye absorbance is shown to be dependent on the three-dimensional sample structure: films (1-D), tubes (2-D), and spheres (3-D). The magnitude of the dimension effect on absorbance is determined by the size of both the sample and the probe beam. Furthermore, dye distribution characteristics in 2-D and 3-D systems also affect absorbance; a dye distributed exclusively to the surface layer of a 2-D or 3-D sample gave an absorbance 0.50- or 0.33-fold of that homogeneously distributed, respectively. If a dye is distributed in the inner volume of the sample alone, absorbance increases over that for homogeneous distribution. Effects of sample dimension, dye distribution characteristics, and the size of the probe beam in absorption microspectroscopy are discussed on the basis of the proposed models, and an experimental check of the models is presented.     

Second-order theories for extensional vibrations of piezoelectric crystal plates and strips

An infinite system of two-dimensional (2-D) equations for piezoelectric plates with general symmetry and faces in contact with vacuum is derived from the 3-D equations of linear piezoelectricity in a manner similar to that of previous work, in which an infinite system of 2-D equations for plates with electroded faces was derived. By using a new truncation procedure, second-order equations for piezoelectric plates with faces in contact with either vacuums or electrodes are extracted from the aforementioned infinite systems of equations, respectively. The second-order equations for plates with or without electrodes are shown to predict accurate dispersion curves by comparing to the corresponding curves from the 3-D equations in a range up to the cut-off frequencies of the first symmetric thickness-stretch and the second symmetric thickness-shear modes without introducing any correction factors. Furthermore, a system of 1-D second-order equations for strips with rectangular cross section is deduced from the 2-D second-order equations by averaging variables across the narrow width of the plate. The present 1-D equations are used to study the extensional vibrations of barium titanate strips of finite length and narrow rectangular cross section. Predicted frequency spectra are compared with previously calculated results and experimental data.     

Objective data alignment and chemometric analysis of comprehensive two-dimensional separations with run-to-run peak shifting on both dimensions.

Data from comprehensive two-dimensional (2-D) separation techniques, such as comprehensive 2-D gas chromatography (GC x GC), liquid chromatography/liquid chromatography (LC x LC) and liquid chromatography/ capillary electrophoresis (LC x CE) can be readily analyzed by various chemometric methods to increase chemical analysis capabilities. A retention time alignment, preprocessing method is presented that objectively corrects for run-to-run retention time variations on both separation dimensions of comprehensive 2-D separations prior to application of chemometric data analysis algorithms. The 2-D alignment method corrects for run-to-run shifting of a sample data matrix relative to a standard data matrix on both separation time axes in an independent, stepwise fashion. After 2-D alignment, the generalized rank annihilation method (GRAM) is successfully applied, substantiating the performance of the alignment method. The alignment method should have important implications, because most 2-D separation techniques exhibit, in the context of chemometric data analysis, considerable run-to-run retention time shifting on both dimensions. Even when there are only three to four points/peak, that is, with three to four separations on the second dimension (column 2) per peak width from the first dimension (column 1), the 2-D alignment coupled with GRAM provides dependable analyte peak identification capabilities and adequate quantitative precision for unresolved analyte peaks. Thus, the 2-D alignment algorithm is applicable to lower data density conditions, which broadens the scope of chemometric analysis to high-speed 2-D separations.     

Construction and performance analysis of 2-D codes for M-ary OFFH?CDMA systems

A new family of two-dimensional (2-D) codes constructed by combining frequency-hop and time-spreading codes is presented. The proposed codes are designed to overcome the limitation imposed on the maximum permissible number of simultaneous users in optical code-division multiple-access (OCDMA) systems. To increase the data transmission rate, the 2-D codes employ a M-ary signalling scheme. The proposed family of codes has the favourable characteristics of a zero autocorrelation constraint and a cross-correlation constraint of one. The performance of the 2-D code is analysed in terms of the bit error rate (BER) and is compared with that of a conventional OCDMA system using optical orthogonal code (OOC). The numerical and simulation results reveal that the proposed system outperforms conventional OCDMA systems both in terms of the BER and the data transmission rate. In addition, the system capacity is sufficient to ensure reliable communication (BERles10^-9) in local area networks     

Extensional,thickness-stretch and symmetric thickness-shear vibrations of piezoceramic disks

A set of two-dimensional (2-D), second-order approximate equations for extensional, thickness-stretch and symmetric thickness-shear vibrations of piezoelectric ceramic plates with electroded faces is extracted from the infinite system of 2-D equations deduced previously. The new truncation procedure developed recently is used for it improves the accuracy of calculated dispersion curves. Closed-form solutions are obtained for free vibrations of circular disks of barium titanate. Dispersion curves calculated from the present approximate 2-D equations are compared with those obtained from the 3-D equations, and the predicted resonance frequencies are compared with experimental data. Both comparisons show good agreement without any corrections. The frequencies of the edge modes calculated from the present 2-D equations are very close to the experimental data. Furthermore, mode shapes at various frequencies are calculated in order to identify the frequency segments of the spectrum at which one of the coupled modes-i.e., the radial extension (R), edge mode (Eg), thickness-stretch (TSt), and symmetric thickness-shear (s.TSh)-is predominant.     

Semi-three-dimensional algorithm for time-resolved diffuse optical tomography by use of the generalized pulse spectrum technique

Although a foil three-dimensional (3-D) reconstruction with both 3-D forward and inverse models provide, the optimal solution for diffuse optical tomography (DOT), because of the 3-D nature of photon diffusion in tissue, it is computationally costly for both memory requirement and execution time in a conventional computing environment. Thus in practice there is motivation to develop an image reconstruction algorithm with dimensional reduction based on some modeling approximations. Here we have implemented a semi-3-D modified generalized pulse spectrum technique for time-resolved DOT, where a two-dimensional (2-D) distribution of optical properties is approximately assumed, while we retain 3-D distribution of photon migration in tissue. We have validated the proposed algorithm by reconstructing 3-D structural test objects from both numerically simulated and experimental date. We demonstrate our algorithm by comparing it with the calibrated 2-D reconstruction that is in widespread use as a shortcut to 3-D imaging and proving that the semi-3-D algorithm outperforms the calibrated 2-D algorithm.     

采用数字微镜获得多目标辐射谱的方法

提出在非扫描工作方式下获得二维分布的多个点目标辐射谱的方法。该方法与其他成像光谱技术最显著的区别在于其光学系统的设计及数字微镜的使用。通过数字微镜进行目标选通,并经过特殊设计的柱面透镜阵列将二维分布的多个目标变换成一维分布,结合光谱仪的使用实现多目标光谱的同时测量,提高了系统信噪比。在可见光波段进行了实验,结果表明该方法是可行的。     

Variable-length two-dimensional modulation coding for imaging page-oriented optical data storage systems

We present what is to our knowledge a new class of two-dimensional (2-D) modulation codes, called variable-length 2-D modulation codes, suitable for page-oriented optical data storage (PODS) systems that write and read data in a 2-D bit image format. These codes overcome the inherent spatial intersymbol interference in imaging PODS systems and improve the code rate performance of previous fixed-length 2-D modulation codes. The codes in this new class map one-dimensional input data blocks of variable lengths to 2-D output data blocks of variable lengths and are designed to limit error propagation. In this study we give several examples of fixed-length and variable-length 2-D modulation codes with various properties for imaging PODS systems. We also compare the bit-error-rate performance of these fixed-length and variable-length codes.     

Measurement by multidirectional interferometers of the position and orientation of a positioning stage

A multidirectional interferometer system is developed to determine the position and orientation of a stage moved in a two-dimensional (2-D) space. In this system four corner-cube prisms are mounted on the moving stage, and four laser beams are incident on the corner cubes in different directions. Moving distances in the observed directions are measured by laser interferometers. The position and orientation of the stage are calculated from the moving distances of the corner cubes. Some experiments are done on the 2-D moving stage with four interferometers, and measurement errors are estimated from redundant data. The estimated accuracy is higher than 0.2 microm for translation and 0.3 x 10(-3) deg for rotation for a measurement range of 0.5 mm and 0.5 deg.     

Automated instrumentation for comprehensive two-dimensional high-performance liquid chromatography of proteins

A comprehensive two-dimensional (2-D) liquid chromatographic separation system is presented. The system uses a microbore cation exchange column, operated under gradient conditions, as the first dimension separation. Effluent from this first column alternately fills one of two loops on a computer-controlled eight-port valve. A second pump then forces loop material onto a second column, a size exclusion column. UV detection is used, and the system is applied to the separation of protein standards and serum proteins. The 2-D system has a higher resolving power and peak capacity than either of the two columns used alone. The entire first column effluent is analyzed on the second column in virtually the same time it takes to complete the first column separation, without the use of stopped flow methods. The entire system is automated and operated under computer control. Three-dimensional (3-D) data representation provides a means of viewing peak profiles in either separation dimension and contour mapping of the 3-D data provides a more reliable means of peak identification from run to run than that provided by single-column elution times.     

Usefulness of ultrasonic strain measurement-based shear modulus reconstruction for diagnosis and thermal treatment

We previously reported an ultrasonic strain measurement-based one-dimensional (1-D) shear modulus reconstruction technique using a regularization method for differential diagnosis of malignancies on human superficial tissues (e.g., breast tissues). Here, ultrasonic strain measurement-based 2-D and 3-D shear modulus reconstruction techniques are described, and the 1-D technique is reviewed and subsequently applied to various human in vivo tissues, including deeply situated tissues (e.g., liver). Because soft tissues are deformed in 3-D space by externally situated arbitrary mechanical sources, the accuracy of the low-dimensional (i.e., 1-D or 2-D) reconstructions is lower to that of 3-D reconstruction due to occurrence of erroneous reconstruction artifacts (i.e., the reconstructed modulus is different than reality). These artifacts are confirmed on simulated inhomogeneous cubic phantoms containing a spherical homogenous inclusion using numerically calculated deformation data. The superiority of quasi-real-time imaging of the shear modulus is then demonstrated by comparing it with conventional B-mode imaging and strain imaging from the standpoints of monitoring the effectiveness of minimally invasive thermal therapy as well as differential diagnosis. Because the 2-D and 3-D techniques require special ultrasonic (US) equipment, the 1-D technique using conventional US imaging equipment is used, even though erroneous artifacts will occur. Specifically, the 1-D technique is applied as a diagnostic tool for differentiating malignancies in human in vivo liver and breast tissue, and a monitoring technique for determining the effectiveness of interstitial electromagnetic wave (micro and rf) thermal therapy on human in vivo liver and calf in vitro liver. Even when using the 1-D technique, reconstructed shear moduli were confirmed to be a suitable measure for monitoring thermal treatment as well as differential diagnosis. These results are encouraging in that they will promote use of 2-D and 3-D reconstruction techniques.