基于八叉树颜色量化和链表统计的背景主色提取方法

背景主色的确定是迷彩伪装的关键问题,针对现有提取方法的不足,提出一种基于八叉树颜色量化和链表统计的背景主色提取算法.首先对图像进行八叉树颜色量化,然后统计量化后图像的颜色,并用链表存储,最后依据人眼视觉特性和相应准则确定背景主色.该算法可以对多 幅图像进行处理且运算时间较短.实验表明这种方法能够满足迷彩伪装颜色确定的要...     

资料同化中的数字滤波弱约束试验及分析

气象数值预报中,由于分析过程引入初始非平衡,从而引起虚假快波振荡,重力波控制弱约束把资料分析过程和初始化过程结合在一起,通过数字滤波弱约束在极小化过程中实现对分析场的平衡约束,克服非平衡问题. 以2008年初的一次南方雨雪天气为研究个例,进行了数字滤波弱约束的同化试验和预报试验,结果表明,数字滤波弱约束4D-Var能充分控制快波振荡的出现和初始调整现象,使得到的分析场不仅能更好的逼近观测,而且能更好地与模式动力相协调. 预报检验的结果表明,在同化过程中施加数字滤波弱约束,能有效滤除由于地形或观测资料等因素 关键词： 变分同化 初始非平衡 数字滤波 弱约束     

Study of radiation background at the north crossing point of the BEPCⅡ in collision mode

Understanding the radiation background at the north crossing point (NCP) in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium (HPGe) detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI(Tl) detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiation distribution in the vicinity of the NCP where the HPGe detector will be located. Synthesizing all obtained information, the shielding for neutron irradiation is studied based on model-dependent theoretical analysis.     

国际地下实验室发展综述

地下实验室是开展粒子物理学、天体物理学及宇宙学等领域一些重大基础性前沿课题的重要研究场所和良好的低本底环境,建设和发展地下实验室对于一个国家的基础科学研究具有重要科学意义.目前,国际上许多国家都已经建立起地下实验室,而中国一直没有很好的地下实验室,特别是极深地下实验室.2009年,清华大学与二滩水电开发有限责任公司开展战略合作,利用锦屏山隧道建立中国首个世界最深的地下实验室--中国锦屏地下实验室(China Jinping Underground Laboratory,CJPL),并于2010年12月12日正式启用.中国锦屏地下实验室的建成,标志着中国已经具备开展物理学重大基础前沿科学研究的自主地下实验平台,对于推动我国相关领域的重大基础前沿课题的自主研究意义重大.文章对国际上一些重要地下实验室的情况进行了介绍,并对中国锦屏地下实验室的基本情况进行了介绍.     

A Framework for Data Partitioning for C++ Data-Intensive Applications

We present an automated framework that partitions the code and data types for the needs of data management in an object-oriented source code. The goal is to identify the crucial data types from data management perspective and separate these from the rest of the code. In this way, the design complexity is reduced allowing the designer to easily focus on the important parts of the code to perform further refinements and optimizations. To achieve this, static and dynamic analysis is performed on the initial C++ specification code. Based on the analysis results, the data types of the application are characterized as crucial or non-crucial. Continuing, the initial code is rewritten automatically in such a way that the crucial data types and the code portions that manipulate them are separated from the rest of the code. Experiments on well-known multimedia and telecom applications demonstrate the correctness of the performed automated analysis and code rewriting as well as the applicability of the introduced framework in terms of execution time and memory requirements. Comparisons with Rational’s Quantify^TM suite show the failure of Quantify^TM to analyze correctly the initial code for the needs of data management.     

A Brief Note on a New Cosmic “Coincidence” and New Physics

The latest results from the Wilkinson Microwave Anisotropy Probe (WMAP) with regard to the Cosmic Microwave Background (CMB) throw up some intriguing results, and the question has been asked “Does this point to new physics?” We point out that indeed all this indicates new physics on the Planck scale.     

WL2.1彩电遥控系统软件开发及相关电路设计

开发有自己特色的遥控系统是国内电视机工厂面临的一个新课题。本文简要介绍了现已投入大批量应用的ＷＬ２．１彩电遥控系统软件的特点，以及相关扫口电路的设计。     

Some new results of IR systems'' sensitivity equations

Typical IR systems' sensitivity equations have been established for decades, these include the NETD equation for IR imaging systems, and the acquisition and tracking range equations for IR searching and tracking systems, but they only fit the specific or simplified conditions. For example, the NETD equation can only be used for systems tested under the standard condition. In the field application, we must deal with the noise equivalent radiance difference NELD, not the NETD, and give out its explicit equation for concrete calculation. For the range equation, when the small target, often called a point source, is not strong enouph, i. e., when the target contrast is seriously decreased, we must consider the unneglectable background effect. In this paper, we summarrize some more general and valuable IR systems' sensitivity equations, which can be used for the practical engineering analysis and projection effectively.     

Cosmology with cluster surveys

Surveys of clusters of galaxies provide us with a powerful probe of the density and nature of the dark energy. The red-shift distribution of detected clusters is highly sensitive to the dark energy equation of state parameterw. Upcoming Sunyaev-Zel’dovich (SZ) surveys would provide us large yields of clusters to very high red-shifts. Self-calibration of cluster scaling relations, possible for such a huge sample, would be able to constrain systematic biases on mass estimators. Combining cluster red-shift abundance with limited mass follow-up and cluster mass power spectrum can then give constraints onw, as well as onσ ₈ and Ω_M to a few per cents.     

Statistical isotropy of the cosmic microwave background

The breakdown of statistical homogeneity and isotropy of cosmic perturbations is a generic feature of ultra-large scale structure of the cosmos, in particular, of non-trivial cosmic topology. The statistical isotropy (SI) of the cosmic microwave background temperature fluctuations (CMB anisotropy) is sensitive to this breakdown on the largest scales comparable to, and even beyond the cosmic horizon. We propose a set of measures,K _l (l = 1, 2,3,...) which for non-zero values indicate and quantify statistical isotropy violations in a CMB map. We numerically compute the predictedK _l spectra for CMB anisotropy in flat torus universe models. Characteristic signatures of different models in theK _l spectrum are noted.