我国同步数字传输装置达国际先进水平

我国第一条全部采用国产设备建成的海口至三亚2.5Gb/s速率同步数字传输(SDH)光通信工程今天在此间通过国家鉴定与验收,从而打破了外国公司对我国SDH技术和市场、尤其是长途干线通信市场的垄断.     

Hotspot Temperatures Reached in Current-Driven Superconducting Niobium Filaments

In a superconducting microbridge too narrow to support vortex motion, the current-induced resistance occurs non-uniformly at definite spots designated as Phase-Slip-Centres (PSC). Further, if the core of a PSC happens to heat above the critical temperature T _c , a PSC may evolve into a normal propagating zone, or hotspot. The PSC’s time of nucleation and the HS minimum current I _h are determined, which allows deriving without ambiguity the rate of heat transfer to the substrate, the latter is compatible with a phonon blackbody radiation model at the Nb/R–sapphire interface. The computation of the HS temperature is then straightforward, while the PSC case is more involved. However, the PSC core temperature can be obtained through an independent determination of the inelastic quasi-particle diffusion length Λ _qp ～2.8 μm. The results of these computations are consistent with all the specific cases, PSCs and HSs, measured experimentally.     

China's Safety Standards of Children's Clothing Has Reached an Advanced International Level

During International Children's Day,various kinds of children's productsbecame popular products in the market,especially children's clothing.Accord-ing to the China National Technical Committee of Standardization of Clothing,three new national standards of children's clothing have been approved and     

诠释2007数码相机单反年

2007年,数码单反相机的价格迅速下降,尤其是消费型数码单反相机的价格已降低到5000元左右,能够为一般消费者所接受,而目前数码单反相机的性能又有了新的提高：千万像素、机身防抖、CCD除尘、生活防水等,很受市场欢迎,因此有人称2007年为数码单反相机年,本文重点介绍几种新上市的数码单反消费型相机,如：佳能EOS400D、尼康D80、索尼A100、宾得K100D、奥林巴斯E-510,供选购时参考。     

液氦温区双小孔型二级脉管制冷机的改进实验

介绍了自行研制的二级双小孔型脉管制冷机的基本结构,着重分析了第二小孔,结构参数冷机性能的影响,指出了进一步改进的方向,经反复实验,采用双小孔结构的二级脉管制冷机第一、二级最低制冷温度分别达到４６Ｋ和３．０Ｋ。     

A Global Optimization Approach to Classification

We reduce the classification problem to solving a global optimization problem and a method based on a combination of the cutting angle method and a local search is applied to the solution of this problem. The proposed method allows to solve classification problems for databases with an arbitrary number of classes. Numerical experiments have been carried out with databases of small to medium size. We present their results and provide comparisons of these results with those obtained by 29 different classification algorithms. The best performance overall was achieved with the global optimization method.     

A Global Selection Procedure for Polynomial Interpolators

The drive for efficient methods of testing design ideas and prototypes, particularly in engineering, has led to a rapid increase in the field of numerical simulation methods using computers, such as finite-element analysis. This increase in popularity has fueled the need for empirical models that interpolate data collected from these simulations. We propose a selection algorithm to efficiently explore an appropriate class of polynomial interpolators. The storage of polynomial models is made efficient and effective thanks to a special coding. Finally, the last stage of the algorithm returns a model that is no longer an interpolator but, having a smaller number of terms, is simpler and easier to handle and understand. In this way, a trade-off between accuracy and simplicity of the model is attained.     

A Global Optimization Approach to Laser Design

The objective of this work is to develop and validate the basis of a novel laser modeling and design methodology that incorporates a global optimization approach. Classical modeling techniques typically involve design evaluations that are conducted at the laser's threshold injection current. This is the point where the laser is just turning on, and the (standard practice) numerical challenge is minimal. The fundamental difference offered by the proposed new methodology is the possibility of developing laser designs directly at the injection current (power level) of interest.The effectiveness of the new methodology is verified by considering the computationally difficult problem of maximizing a laser's internal (cavity) field flatness over a range of above-threshold injection currents, while also considering the boundary condition error of the laser's internal field solution. Global optimization is then used to find an optimally flat field solution in terms of the laser's structural design parameters. The favorable comparison between our results and the results obtained by the extrapolation of threshold designs to the same injection current indicate the self-consistency and fundamental capabilities of the new methodology.     

基于栅格的全局光子图重建

基于光子图的光子映射算法能产生高质量的照片级图像.对于光照复杂的场景,光子图需要存储大量光子以提高生成图像的质量,这不仅占用大量的内存空间,而且光照估计的时间长.论文提出基于栅格的全局光子图重建的算法,即在光子包围盒被栅格化后,其非空栅格中一定比例的光子被用来重建新的光子图,并保证重建前后栅格内光子能量和守恒,这使得重建前后光子图的光照估计的效果相近.通过增加特定栅格中的重建光子数目,能有效减少由几何偏差引起的光照估计误差,增强直接聚焦(焦散)和间接聚焦光照的绘制效果;并使用简单方法检测生成图像中少量噪声,增加少量采样即可有效减少相应的噪声.全局光子图重建算法的计算成本低,并保持生成图像的视觉独立性.     

A Noise-Tolerant Hybrid Model of A Global and A Local Learning Module

Proposed is GLLL2, a hybrid architecture of a global and a local learning module, which learns default and exceptional knowledge respectively from noisy examples. The global learning module, which is a feedforward neural network, captures global trends gradually, while the local learning module stores local exceptions quickly. The latter module distinguishes noise from exceptions, and learns only exceptions, which makes GLLL2 noise-tolerant. The results of experiments show the process in which training examples are formed into default and exceptional knowledge, and demonstrate that the predictive accuracy, the space efficiency, and the training efficiency of GLLL2 is higher than those of each individual module.

     

线性乘性规划的全局优化算法

本文研究线性乘性规划问题(LMP)的全局最优化算法,线性乘性规划问题在生产运输、工厂布局设计、超大规模集成电路芯片设计等方面有重要的应用。首先将LMP问题转化为等价规划问题(P1),然后利用参数线性化方法在相应的超矩形上求得问题(P1)的目标函数和约束函数线性下界估计,并提出了一个求线性乘性规划全局解的确定性全局优化算法,并证明了算法的收敛性。数值实验表明提出的方法是可行和有效的。     

Global knowledge management research: A bibliometric analysis

The present study characterizes the dynamic publication activity of global knowledge management (KM) by data collected through a search restricted to articles in ISI Web of Science.A total of 2727 unique authors had contributed 1407 publications since 1975. The overwhelming majority (2349 or 86%) of them wrote one publication. The productive authors, their contribution and authorship position are listed to indicate their productivity and degree of involvement in their research publications. The sum of research output of the first or responsible authors from USA, UK and Germany reaches 57% of the total productivity. The distribution of articles is rather widespread - they published in 462 titles of serials, spanning 110 Journal Citation Reports subject categories. The higher quality journals make publication of findings more visible. A Pearson's correlation coefficient is statistically found to be significant between citation frequency of article and impact factor of journal, instead of authorship pattern. The results also indicate that R&D expenditures were actually not proportional to research productivity or citation counts. As the subject highly interacts with other disciplines, the field of KM has not yet developed its own body of literature. KM might have been evolving an interdisciplinary theory that is developing at the boundaries of scientific disciplines. This revised version was published online in June 2006 with corrections to the Cover Date.     

金属合金LBE全局物态方程的初步研究

基于单质全局物态方程模型QEOS(Quotidian equation of state),通过求解平均原子模型的混合物Thomas-Fermi方程以及将混合元素平均为单一虚拟元素的方法得到了混合物状态方程。对铅铋混合物LBE的物态方程做了初步研究,计算了LBE在给定温度与密度下的压强、电离度等,并分析了电离平衡和不同温度、密度下电子及离子对总压强的贡献。     

走进原杨一家韩国本土设计公司的国际化视野

2009年2月．di焦点城市专题报道了韩国首尔作为世界设计之都的创意文化与设计实力．尤其关注了韩国建筑当下的状况。今天．我们再次将目光聚焦在这个充满创意的国度。