超灵敏检漏的实时校准

超灵敏检漏的实时校准是国际上尚未解决且未标准化的一个难题,本文利用自建的微流量参考漏率系统对商用检漏仪和超灵敏检漏系统进行了实时校准的实验研究,在10-14Pa.m3/s~10-10Pa.m3/s宽范围漏率内实现了对检漏仪器的实时校准。     

Characteristics for Leveraging Value Management Processes on Capital Facility Projects

A more competitive business environment requires that a variety of value management process (VMP) options be continuously introduced into the construction industry. Project stakeholders and managers are highly concerned about value maximization through implementation of one or more beneficial VMP options. The objective of this study is to identify the most leveraging project characteristic factors (PCFs) in need of VMP implementation. Furthermore, the levels of importance of each PCF in association with the optional VMPs are quantified to effectively assess the applicability of VMP implementation using the fuzzy-based analytic hierarchy process method. Four real-case validation tests provide robust research findings. The proposed project assessment tool is useful in evaluating individual projects in terms of whether the subject project is leveraged or has much to be improved by implementing the optional VMPs. The results of this study can facilitate a rigorous evaluation of a project and eventually help the decision-making process in selecting the most beneficial VMP options to maximize the optimum project value.     

Advanced photospacers with elastic recovery

A new series of photospacers has been prepared with different types of crosslinkers to improve elastic recovery. Afunctional crosslinker with six reactive groups demonstrates the best elastic recovery. As the quantity of crosslinker is increased, the elastic recovery also increases, probably due to an increase in the crosslinking density. The use of ADMS EPS® results in high resolution, good uniformity, and high production yield in the liquid‐crystal‐display (LCD) process. Especially, EPS® improves and solves problems such as viewing angle, crosstalk, and dark spots.     

考虑显微组织影响的焊接接头疲劳裂纹扩展寿命估算

本文讨论了焊接头的微观金相组织及其对疲劳裂纹生长率的影响,用标准试样的裂纹扩展速率数据,考虑微观组织的影响建立了疲劳裂纹在不同区域扩展的疲劳模型,并用这些模型编制计算机程序估算了裂纹的扩展寿命。与实验值进行了比较。     

原子团离子在Al_(x)Ga(1-x)As基体组分SIMS定量分析中的应用

通过检测原子团离于MCs 和MAs－（M是基体元素）对AlxGa1-xAs基体组分进行了定量的分析，考察了MIQ－156SIMS上所测这些原子团离子的能量分布及其对分析结果的影响，并对正、负SIMS测量方法做出比较。     

Preliminary announcement of an 85 percent efficient reflector antenna

This communication is our preliminary announcement and claim for achievement of 85 percent aperture efficiency using a dual reflector antenna. We are aware of no other reflector antenna having such aperture efficiency, and we invite the antenna community to comment, critique, or inform us of equal or better claims. A full report will be forthcoming; this brief note will supply only pertinent highlights.     

Optical implementation of the hopfield neural network with matrix gratings

We propose a new method for the optical implementation of the Hopfield neural network with a universal tool. The tool is a matrix grating constituted with a group of element gratings. The algorithms for designing a matrix grating are proposed, and a matrix grating is created to execute recognition experiments by use of the Hopfield neural network. The experimental results demonstrate that the proposed method performs well. The stability of the light efficiencies of different optical components used in optical networks is also considered.     

A fracture criterion for three-dimensional crack problems

A criterion for predicting the growth of three-dimensional cracks is developed on the basis of the strain energy density concept which has been used successfully for treating two-dimensional crack problems. Fracture is assumed to initiate from the nearest neighbor element located by a set of spherical coordinates (r, θ, φ) attached to the crack border. The new fracture surface is described by a locus of these elements whose locations correspond to the strain energy function, dW/dV, being a minimum. The function dW/dV is found to be singular of the type 1/r and is of quadratic form in the three stress intensity factors k₁, k₂ and k₃ expressed through the strain energy density factor S. It is postulated that unstable crack propagation initiates from a region where S reaches a critical value S_cr = r₀(dW/dV)_cr. The locations of failure lying on the fracture surface is determined by holding (dW/dV)_cr = S_min/r₀ constant. The quantity S_min stands for the value of S minimized with respect to θ and φ and r₀ is a radial distance measured from the crack border.

An example of failure prediction for an embedded elliptical crack subjected to both normal and shear loads is presented. According to the S-criterion, fracture initiation takes place at the ends of the minor axis. An unexpected result is that for a narrow elliptical crack and Poisson's ratio of 1/3 the lowest failure load occurs when the uniaxial tensile load makes an angle of approximately 60° with the crack surface and is in the plane of the major axis. This is in contrast to the expectation that the lowest critical load occurs when the uniaxial tension is perpendicular to the crack surface. In the limit as the elliptical crack becomes increasingly narrower, the result reduces to the two dimensional line crack case of Mode I and III loading. The S-criterion is also applied to the failure prediction of three dimensional cracks under compressive loads.     

A 2.4-GHz Low-Power Low-IF Receiver and Direct-Conversion Transmitter in 0.18-μm CMOS for IEEE 802.15.4 WPAN Applications

In this paper, a low-power low-IF receiver and a direct-conversion transmitter (DCT) suitable for the IEEE standard 802.15.4 radio system at the 2.4-GHz band are presented in 0.18-mum deep n-well CMOS technology. By using vertical NPN (V-NPN) bipolar junction transistors in the baseband analog circuits of the low-IF receiver, the image rejection performance is improved and the power consumption is reduced. In addition, by applying the V-NPN current mirrored technique in a DCT, the carrier leakage is reduced and the linearity performance is improved. The receiver has 10 dB of noise figure, -15 dBm of third-order input intercept point, and 35 dBc of image rejection. The transmitter has more than -2 dBm of transmit output power, -35 dBc of local oscillator leakage, and -46 dBc of the transmit third harmonic component. The receiver and transmitter dissipate 6 and 9 mA from a 1.8-V supply, respectively