新时期计算机硬件故障分析及维修技巧探讨

随着计算机使用时限的增长,计算机硬件由于人为操作不当、老化等原因,通常发生许多故障,影响人们使用的感知。本文阐述了CPU、主板、内存、硬盘和显示器等部件的维修技巧,详细地分析了硬件故障产生的原因及诊断方法,以便为同行做出参考。     

Factors influencing tenderness in steaks from Brahman cattle

The objective of this study was to identify a set of explanatory variables for Warner-Bratzler shear force and myofibril fragmentation indices after 7, 14, and 21d of aging; and sensory tenderness after 14d of aging of steaks from Brahman cattle. Insoluble collagen was negatively associated (P<0.001) with all tenderness traits across aging periods, and regression coefficients ranged from 5.69±0.49 to 9.12±0.29N for Warner-Bratzler shear force. The effect of lean color score (P<0.05) in analyses of unadjusted traits was diminished when data were adjusted for contemporary group (calves of the same sex, fed in one pen, and slaughtered the same day). Insoluble collagen may be of special importance and offer a unique opportunity to improve palatability of steaks from purebred Brahman cattle.     

PLC可编程控制器应用于乙醇汽油调和系统

在某油库采用PLC可编程控制器进行乙醇汽油自动付油的试验和应用,对比原来的抄表手动抄数,该系统采用西门子S7-300系列PLC控制,实现了付油过程的自动化.经过几年的运行,取得了较好的效果.实践证明,可编程控制器应用于乙醇汽油自动付油系统成熟可靠,具有良好的应用前景.     

名寺名画古道古风北京法海寺旅游区规划

规划整合了区域内的历史文化资源,对文物资源丰富的北京市进行了"文物旅游"探索,将法海寺旅游区划分为法海寺壁画艺术景区、承恩寺宗教文化景区、田义墓石刻艺术景区三部分,并体现于功能分区、空间结构、分区规划各个阶段,力求在社会转型时期和各种利益、矛盾比较尖锐的城乡结合部,确保群众利益优先的前提下,使文物保护、文化传承、旅游开发和生态建设等方面平衡发展。     

Radiometric validation of NASA's Ames Research Center's Sensor Calibration Laboratory

The National Aeronautics and Space Administration's (NASA's) Ames Research Center's Airborne Sensor Facility (ASF) is responsible for the calibration of several airborne Earth-viewing sensor systems in support of NASA Earth Observing System (EOS) investigations. The primary artifact used to calibrate these sensors in the reflective solar region from 400 to 2500 nm is a lamp-illuminated integrating sphere source. In September 1999, a measurement comparison was made at the Ames ASF Sensor Calibration Facility to validate the radiometric scale, establish the uncertainties assigned to the radiance of this source, and examine its day-to-day repeatability. The comparison was one of a series of validation activities overseen by the EOS Calibration Program to ensure the radiometric calibration accuracy of sensors used in long-term, global, remote-sensing studies. Results of the comparison, including an evaluation of the Ames Sensor Calibration Laboratory (SCL) measurement procedures and assigned radiometric uncertainties, provide a validation of their radiometric scale at the time of the comparison. Additionally, the maintenance of the radiance scale was evaluated by use of independent, long-term, multiyear radiance validation measurements of the Ames sphere source. This series of measurements provided an independent assessment of the radiance values assigned to integrating sphere sources by the Ames SCF. Together, the measurements validate the SCF radiometric scale and assigned uncertainties over the time period from September 1999 through July 2003.     

A normative database of thumb circumduction in vivo: center of rotation and range of motion

This article reports a systematic research effort aimed at establishing a normative database of thumb circumduction range of motion (ROM) and related kinematic characteristics in vivo while examining the effects of anthropometry, gender, and direction of rotation. Twenty-eight (14 men, 14 women) anthropometrically diverse participants performed maximum voluntary thumb circumductions as the trajectories of the surface markers placed on their thumb landmarks were recorded by an optoelectronic motion capture system. A globographic representation method was employed to model the measured marker trajectories, determining the center of rotation and central reference axes for thumb circumduction. Thumb ROM was quantified using (a) the joint sinuses expressing the thumb orientation change with respect to the reference axes and (b) cone volumes circumscribed by the thumb at the distal phalangeal, interphalangeal, and metacarpophalangeal levels. Data analyses resulted in statistical summaries of the derived kinematic and ROM measures with significant effects identified and regression equations predicting the cone volumes. Potential applications of this research include ergonomic design of hand-operated controls or devices and evaluation of thumb impairments or disorders.     

Glasses removal from facial image using recursive error compensation

In this paper, we propose a new method of removing glasses from a human frontal facial image. We first detect the regions occluded by the glasses and generate a natural looking facial image without glasses by recursive error compensation using PCA reconstruction. The resulting image has no trace of the glasses frame or of the reflection and shade caused by the glasses. The experimental results show that the proposed method provides an effective solution to the problem of glasses occlusion and we believe that this method can also be used to enhance the performance of face recognition systems.     

Towards molecular spintronics

The ability to manipulate electron spin in organic molecular materials offers a new and extremely tantalizing route towards spin electronics, both from fundamental and technological points of view. This is mainly due to the unquestionable advantage of weak spin-orbit and hyperfine interactions in organic molecules, which leads to the possibility of preserving spin-coherence over times and distances much longer than in conventional metals or semiconductors. Here we demonstrate theoretically that organic spin valves, obtained by sandwiching an organic molecule between magnetic contacts, can show a large bias-dependent magnetoresistance and that this can be engineered by an appropriate choice of molecules and anchoring groups. Our results, obtained through a combination of state-of-the-art non-equilibrium transport methods and density functional theory, show that although the magnitude of the effect varies with the details of the molecule, large magnetoresistance can be found both in the tunnelling and the metallic limit.     

DNA microarray stochastic model

A stochastic model of the DNA microarray image pixels is presented. The model includes spot pixel intensity distribution, interpixel correlations and the intensity distribution of background noise. The data is indicative of a small exponential additive noise process and a larger Gaussian fluctuation that scales with spot intensity. Correlations are observed among pixels in the spot and between test and control images. The correlated fluctuations may be attributed to variations across each spot in the amount of DNA placed on the spot during the array fabrication process. The model may be used in gene expression estimation algorithm development, both to test new algorithms through simulation and to develop optimum algorithms. The model should also be easily adapted to new array based technologies in proteomics.