PLNoise: a package for exact numerical simulation of power-law noises

Many simulations of stochastic processes require colored noises: here I describe a small program library that generates samples with a tunable power-law spectral density: the algorithm can be modified to generate more general colored noises, and is exact for all time steps, even when they are unevenly spaced (as may often happen in the case of astronomical data, see e.g. [N.R. Lomb, Astrophys. Space Sci. 39 (1976) 447]. The method is exact in the sense that it reproduces a process that is theoretically guaranteed to produce a range-limited power-law spectrum 1/f1+β with −1<β?1. The algorithm has a well-behaved computational complexity, it produces a nearly perfect Gaussian noise, and its computational efficiency depends on the required degree of noise Gaussianity.

Program summary

Title of program: PLNoiseCatalogue identifier:ADXV_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXV_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions: noneProgramming language used: ANSI CComputer: Any computer with an ANSI C compiler: the package has been tested with gcc version 3.2.3 on Red Hat Linux 3.2.3-52 and gcc version 4.0.0 and 4.0.1 on Apple Mac OS X-10.4Operating system: All operating systems capable of running an ANSI C compilerNo. of lines in distributed program, including test data, etc.:6238No. of bytes in distributed program, including test data, etc.:52 387Distribution format:tar.gzRAM: The code of the test program is very compact (about 50 Kbytes), but the program works with list management and allocates memory dynamically; in a typical run (like the one discussed in Section 4 in the long write-up) with average list length 2⋅¹⁰⁴, the RAM taken by the list is 200 Kbytes.External routines: The package needs external routines to generate uniform and exponential deviates. The implementation described here uses the random number generation library ranlib freely available from Netlib [B.W. Brown, J. Lovato, K. Russell, ranlib, available from Netlib, http://www.netlib.org/random/index.html, select the C version ranlib.c], but it has also been successfully tested with the random number routines in Numerical Recipes [W.H. Press, S.A. Teulkolsky, W.T. Vetterling, B.P. Flannery, Numerical Recipes in C: The Art of Scientific Computing, second ed., Cambridge Univ. Press, Cambridge, 1992, pp. 274-290]. Notice that ranlib requires a pair of routines from the linear algebra package LINPACK, and that the distribution of ranlib includes the C source of these routines, in case LINPACK is not installed on the target machine.Nature of problem: Exact generation of different types of Gaussian colored noise.Solution method: Random superposition of relaxation processes [E. Milotti, Phys. Rev. E 72 (2005) 056701].Unusual features: The algorithm is theoretically guaranteed to be exact, and unlike all other existing generators it can generate samples with uneven spacing.Additional comments: The program requires an initialization step; for some parameter sets this may become rather heavy.Running time: Running time varies widely with different input parameters, however in a test run like the one in Section 4 in this work, the generation routine took on average about 7 ms for each sample.     

Fe掺杂LSCCF对中低温固体氧化物燃料电池ITSOFC短期输出性能的影响

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目前由于相当数量的小型阀控式铅蓄电池质量不可靠，如循环寿命短、自放电大、电解液超前干涸、高温敏感易热失控等，正面临着市场的严峻挑战。分析其原因主要有：生产厂家大多为小型乡镇企业，技术力量差；板栅合金材料的质量达不到规定标准；对电池“贫液”认识不足，不能正确把握有效含酸量；不能有效控制电池内气体压力，密封性能得不到保证。文中提供了解决上述问题的一些途径和有关技术数据。     

胶原钙维素的研制及其动物应用试验的研究

从猪皮中提取胶原蛋白，经复合钙及ＶＡ、ＶＤ等制成胶原钙纺素。通过酶法、酸碱法和高温水解法提取的试验比较，以高温水解法较适宜。经动物试验表明，胶原钙维素在补血、补骨及胶原代谢等方面有良好的作用，与阿胶对照未显显著差别（Ｐ〉０．０５），对贫血大白鼠周围血象的影响优于阿胶。     

深循环用铅钙合金板栅极板的固化

国内电源界最具影响力的3家专业刊物从2003年下半年至今相继介绍了铅镉合金用于深循环使用的优势。但铅镉不是惟一的合金,镉是致癌物,在生物或植物中有蓄积性危害,应以不宣传、不使用为宜。笔者认为铅钙合金只要适当提高锡含量,采用有针对性的特定固化工艺,改善板栅—活性物质界面的导电性,提高活性物质与板栅的粘附力,完全可以满足深循环长寿命的需要。     

Structure and Transport Properties of La0.67Ca0.33Mn1-xAlxO3

The effects of Al ion doping on the Mn site were studied for the colossal magnetoresistance material La0.67Ca0.33MnO3. It is found that the volume of the crystal cell decreases monotonically when the population of Al3 increases across the entire doping range. As the Al3 population increases, the resistance of the material rises rapidly, while the insulator-metal transition temperature TIM decreases linearly. At small Al3 dosage, a thermal activation model properly describes the transport properties at T>TIM, while a metallic model is more suitable at T相似文献   

‘Beautiful’ unconventional synthesis and processing technologies of superconductors and some other materials

Abstract

Superconducting materials have contributed significantly to the development of modern materials science and engineering. Specific technological solutions for their synthesis and processing helped in understanding the principles and approaches to the design, fabrication and application of many other materials. In this review, we explore the bidirectional relationship between the general and particular synthesis concepts. The analysis is mostly based on our studies where some unconventional technologies were applied to different superconductors and some other materials. These technologies include spray-frozen freeze-drying, fast pyrolysis, field-assisted sintering (or spark plasma sintering), nanoblasting, processing in high magnetic fields, methods of control of supersaturation and migration during film growth, and mechanical treatments of composite wires. The analysis provides future research directions and some key elements to define the concept of ‘beautiful’ technology in materials science. It also reconfirms the key position and importance of superconductors in the development of new materials and unconventional synthesis approaches.