Effect of Nano-SiC and Nano-Si Doping on Critical Current Density of MgB_2

The discovery of superconductivity in magnesium diboride (MgB2) has opened up a new field in materials science research. It offers a possibility of a new class of high performance superconducting materials for practical applications because of the relatively low cost of fabrication, high critical current densities (Jc) and fields, large coherence length, absence of weak links, higher Tc(TC = 39K) compared with Nb3Sn and Nb-Ti alloys (two or four times that of Nb,,Sn and Nb-Ti alloys). However, the weak flux pinning in the magnetic field remains a major challenge. This paper reports the most interesting results on nanomaterial (SiC and Si) doping in magnesium diboride. The high density of nano-scale defects introduced by doping is responsible for the enhanced pinning. The fabrication method, critical current density, microstructures, flux pinning and cost for magnesium diboride bulks, wires and tapes are also discussed. It is believed that high performance SiC doped MgB2 will have a great potential for m     

Density-based clustering method in the moving object database

With the rapid advance of wireless communication, tracking the positions of the moving objects is becoming increasingly feasible and necessary. Because a large number of people use mobile phones, we must handle a large moving object database as well as the following problems. How can we provide the customers with high quality service, that means, how can we deal with so many enquiries within as less time as possible? Because of the large number of data, the gap between CPU speed and the size of main memory has increasing considerably. One way to reduce the time to handle enquiries is to reduce the I/O number between the buffer and the secondary storage. An effective clustering of the objects can minimize the I/O-cost between them. In this paper, according to the characteristic of the moving object database, we analyze the objects in buffer, according to their mappings in the two-dimension coordinate, and then develop a density-based clustering method to effectively reorganize the clusters. This new mechanism leads to the less cost of the I/O operation and the more efficient response to enquiries.     

川西平原农田啮齿动物群落变量的模拟研究

利用Monte Carlo方法，模拟了川西平原农田啮齿动物群落变量的总和、年间和月间变动情况及统计学特征，其变量是：物种数、生物量、物种多样性和均匀性。真实群落4个变量的所有值均在模拟群落变量的95％置信区间内。物种数和物种多样性显示出了相似的变动规律。真实群落4个变量与模拟群落4个变量也显示出了相似的变动规律。当零假设为这些变量服从正态分布时，用单样本Kolmogorov-Smirnov方法检验，得到的结果与偏度和峭度显示的结果并不完全一致。结果说明，要估计一个变量的置信区间，需要有足够大的样本含量。     

地下水对浅基础地基承载力的影响

结合国标《建筑地基基础设计规范》(GB5007-2002)中所阐述的确定地基承载力的方法,定性的分析了在弹塑体假定条件下,地基承载力受地下水位在基底塑性区开展深度范围内变化时的影响程度,简述了地基承载力受地下水的影响程度与基底土层的粘聚力 C、土的内摩擦角Ф、及上部结构间的关系,指出地下水位在枯水期和丰水期的上下波动对地基的稳定性存在不利影响,而在实际工程设计中此影响往往容易忽视,希望设计者要根据实际情况,充分考虑到这种不利因素,保证上部结构的安全与稳定。     

Semi-order Fuzzy Supermartingales and Submartingales

There are some mathematical models(see Example2.4)and analogous results in standard martingale theorywhich can not be described by the usual fuzzy martingaletheory because of the lack of corresponding semi-orderin the fuzzy number space(E~n,D).In this paper,asuitable semi-order in the fuzzy number space(E~n,D)and the semi-order fuzzy supermartingale and submar-tingale are introduced,the charaterlstics of semi-ordersupermartingales and submartingales,as well as theDood's stopping theorem for them(the bounded stoppingtimes theorem and the general stopping times theoremfor a class of closable semi-order fuzzy supermartin-gales and submartingales)are established.     

Laplace Transformation and Ergodic Potential Kernel for q-Process in Random Environment

This paper introduces some concepts such as q-process in random environment, Laplace transformation, ergodic potential kernel, error function and some basic lemmas.We study the continuity and Laplace transformation of random transition function. Finally, we give the sufficient condition for the existence of ergodic potential kernel for homogeneous q-processes in random environments.     

非线性规划中的约束变尺度法(续)

系统地介绍了非线性规划中的约束变尺度法的基本思想和方法。并就Maratos效应的克服、变尺度矩阵的修正、相容性以及约束变尺度法中的可行方法等问题研究的最新成果进行较为详细的介绍。     

1.3μm InGaAsp/Inp DCC结构对激光器阈值和T_0值的影响

研究了 1 .3 μmInGaAsp InpDCC结构中间夹层厚度对激光器阈值和T0 值的影响 ,并得到了最佳的夹层厚度     

EC,ASMC and Macrophage Oxidize Human Low Density Lipoprotein

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C 语言深度剖析

通过一种对C语言进行反编译的方法，分析了C语言中局部变量与全局变量在内存中的存储方式，并说明了对它的使用。