无线座机强攻固话市场

随着中国电信189放号。中国移动也开始紧张起来。毕竟,全业务竞争时代的第一场大战已经到来。针对中国电信旨在抢夺中国移动全球通用户的“天冀”计划。中国移动也准备把自己精心打造的另一把利刃——TD无线座机业务推向市场。不难看出。中国移动一边积极筹备TD三期建设。一边却在有计划地打入固话市场。截至目前。广东TD无线座机产品测试已经结束。联想移动,TCL通讯、华为,     

A robust volumetric apparatus and method for measuring high pressure hydrogen storage properties of nanostructured materials

A volumetric apparatus to measure hydrogen adsorption and desorption at room temperature and up to 100 atm has been constructed and studied for accuracy, reproducibility, and stability. The design principles are presented and considerable attention to detail is given to examine the effects of diurnal temperature changes in the manifold and helium adsorption by carbon-based adsorbents during free volume measurement. A heuristic for helium correction is derived from a model with a basis in literature and verified through calculation of adsorbent density. Several materials with well-known hydrogen capacities are studied to examine reproducibility. The microporous carbon AX-21 is studied to examine the effects of pressure step size and approach to equilibrium caused by gas mixing and the Joule-Thomson effect. Hydrogen spillover on a hybrid material, Pt on templated carbon, is examined for several loadings of metal. Kinetics of both physisorption and spillover are compared via the diffusion time constant (D/R(2)) estimated by fitting models for pore and surface diffusion to time-dependent adsorption profiles. No concentration dependence was found for pore diffusion; however, the surface diffusion time constant was shown to decrease with respect to increasing hydrogen concentration.     

Slow-flow measurements and fluid dynamics analysis using the Fresnel drag effect

We have employed a Sagnac interferometer to measure small optical phase shifts induced by the Fresnel drag effect on moving media. The system detects volumetric flow rates of water as slow as 43 μL/min while maintaining a small pressure drop across the measuring pipe. Velocity profiles and turbulence measurements of flowing water are also demonstrated and discussed.     

Microwave spectroscopy of the Mars atmosphere

A study of the use of millimeter-wavelength spectral transitions to investigate the atmosphere of Mars is presented. In the model experiments investigated it is assumed that a spectrometer in the frequency range from 100 to 260 GHz looks into a modest-sized telescope of from 30 to 50 cm aperture from a near-Mars orbit. The molecules H(2)O, CO, O(2), O(3), and H(2)O(2) all have intense spectral lines in the Mars atmosphere in this frequency range and in addition are all very important in understanding the water cycle, the photochemistry, and the circularization in that atmosphere. It is shown that the altitude and the zonal distribution of H(2)O can be mapped even in atmospheric columns as dry as 0.25 precipital μm. Ozone can be mapped over the entire planet, independent of solar-lighting conditions, dust loading, or clouds in the atmosphere, because millimeter waves are insensitive to any particles that can be suspended in the Mars atmosphere. Because the signal-receiving techniques use superheterodyne devices and narrow spectral lines, zonal and meridional winds can be measured at altitudes above 10 km with a precision approaching approximately 3 m/s by the use of Doppler shifts. Temperature-pressure profiles can be measured to altitudes of 100 km by the use of CO lines in the limb-sounding mode.     

太阳能吸收AAO复合氧化膜的制备与性能

通过阳极氧化技术制备高度有序的多孔阳极氧化铝(AAO),交流扩孔后,在不同条件下向氧化铝孔内以50Hz的交流频率沉积Cu-Ni纳米复合粒子。经光谱测试分析可知:在电压12V、时间600s、温度25℃条件下制备的涂层具有良好的太阳光吸收性能,吸收率为0.91、发射率为0.18、品质因子为4.9。经SEM,XRD分析可知,复合氧化膜涂层表面得到CuAl_2O_4/Cu-Ni复合纳米棒阵列。目标涂层经600℃高温处理后,吸收率、发射率波动很小,涂层体系的热稳定性得到提高。其中,CuAl_2O_4的存在限制高温环境下Cu,Ni金属颗粒在界面处的扩散,减小氧化概率。     

Automated analysis of nerve-cell images using active contour models

The number of nerve fibers (axons) in a nerve, the axon size, and shape can all be important neuroanatomical features in understanding different aspects of nerves in the brain. However, the number of axons in a nerve is typically in the order of tens of thousands and a study of a particular aspect of the nerve often involves many nerves. Potentially meaningful studies are often prohibited by the huge number involved when manual measurements have to be employed. A method that automates the analysis of axons from electron-micrographic images is presented. It begins with a rough identification of all the axon centers by use of an elliptical Hough transform procedure. Boundaries of each axons are then extracted based on active contour model, or snakes, approach where physical properties of the axons and the given image data are used in an optimization scheme to guide the snakes to converge to axon boundaries for accurate sheath measurement. However, false axon detection is still common due to poor image quality and the presence of other irrelevant cell features, thus a conflict resolution scheme is developed to eliminate false axons to further improve the performance of detection. The developed method has been tested on a number of nerve images and its results are presented.     

Photorefractive processing for large adaptive phased arrays

An adaptive null-steering phased-array optical processor that utilizes a photorefractive crystal to time integrate the adaptive weights and null out correlated jammers is described. This is a beam-steering processor in which the temporal waveform of the desired signal is known but the look direction is not. The processor computes the angle(s) of arrival of the desired signal and steers the array to look in that direction while rotating the nulls of the antenna pattern toward any narrow-band jammers that may be present. We have experimentally demonstrated a simplified version of this adaptive phased-array-radar processor that nulls out the narrow-band jammers by using feedback-correlation detection. In this processor it is assumed that we know a priori only that the signal is broadband and the jammers are narrow band. These are examples of a class of optical processors that use the angular selectivity of volume holograms to form the nulls and look directions in an adaptive phased-array-radar pattern and thereby to harness the computational abilities of three-dimensional parallelism in the volume of photorefractive crystals. The development of this processing in volume holographic system has led to a new algorithm for phased-array-radar processing that uses fewer tapped-delay lines than does the classic time-domain beam former. The optical implementation of the new algorithm has the further advantage of utilization of a single photorefractive crystal to implement as many as a million adaptive weights, allowing the radar system to scale to large size with no increase in processing hardware.     

乡城水电站古河床地质条件下的隧洞开挖与初期支护

乡城水电站引水隧洞长约16.37km,由于洞线长,地质探洞布置少,地质勘察资料很难准确地揭示隧洞沿线地质情况,水电九局承建S3+600m以前段即出现招投标文件中未曾提及的古洞床地质,隧洞沿线均为极松散的砂砾石胶结体,加之地下水丰富,洞室稳定性极差,施工过程中遵循短进尺、弱爆破、少扰动、强支护、速支护的原则,同时采用超前管棚、自进式锚杆等工艺确保了施工安全。     

星敏感器技术

80年代初星敏感器技术已经被应用于卫星和航天器的姿态测量和控制系统中;星敏感器技术包括光学、机械、电子线路、软件以及标定和验证实验。目前,其姿态测量精度优于5角秒;发展趋势是小型一体化、低功耗、高精度、输出接口标准化。