The origin of the modulated structure in Sr2CuO3+δ (δ = 0.4): [CuO2] in-plane oxygen vacancy or apical oxygen vacancy?

We propose the question of the modulated structures of copper oxide is caused by the [CuO₂] in-plane oxygen vacancy or apical oxygen vacancy. Sr₂CuO_3+δ single-crystal samples were prepared using high-temperature and high-pressure methods. The major phase of Sr₂CuO_3+δ (δ = 0.4) single-crystal system is found to be constituted by the 5 a modulated structure with the Fmmm space group, which originates from the [CuO₂] in-plane oxygen vacancy appearing in octahedral Cu-O. Besides, the presence of the [CuO₂] in-plane oxygen vacancy may obliterate the superconductivity of the system. Experimental results deduce that the oxygen vacancy may appear in the apical oxygen sites in high-temperature copper oxide superconductors.     

A dynamic SVR–ARMA model with improved fruit fly algorithm for the nonlinear fiber stretching process

Natural Computing - The fiber stretching process plays the key role in the process of fiber production and its effects is measured by the stretching ratio. The stretching ratio is determined by the...     

High molecular weight poly(butylene terephthalate-co-butylene 2,5-furan dicarboxylate) copolyesters: From synthesis to thermomechanical and barrier properties

Poly(butylene terephthalate-co-butylene 2,5-furandicarboxylate) copolyesters (PBTFs) were synthesized from 1,4-butanediol, dimethyl terephthalate (DMT), and 2,5-furandicarboxylic acid (FDCA) by a two-step polymerization method. Their chemical structures were confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and carbon nuclear magnetic resonance before thermal properties were explored with differential scanning calorimeter and thermogravimetric analyzer. Results showed that PBTFs changed from semi-crystalline to completely amorphous when the content of FDCA unit was increased to 45 mol% at first, and then became crystallographic again with the further increment of FDCA unit to 75 mol%. For their mechanical properties, the tensile modulus and strength showed the similar trend, decreasing firstly and then increasing later. Their barrier to carbon dioxide and oxygen became better with the increasing of furan content due to the rigidity and higher polarity of furan ring. The performance of PBTFs copolyesters was investigated clearly, and the relative content of FDCA and DMT can be adjusted to satisfy different performance requirements.     

北京冬奥会推动国内制冷行业可持续发展

二氧化碳制冷技术和提升氨制冷安全体系是绿色制冷的重要支撑,北京冬奥会大量采用绿色制冷技术,不仅推动国内制冷行业可持续发展,而且将对2030年碳达峰和2060年碳中和产生深远影响.     

利用高频结构仿真器分析波导魔T

高频结构仿真器（HFSS）是一种微波器件设计软件，该软件界面友好，通过仿真计算减小了调试工作量，使得微波器件的设计变得简单易行。本文利用HFSS对波导魔T进行了仿真分析，得到了该器件的S参数和动、静态场的分布情况，并对该器件进行了优化设计。     

有关工程建设管理现状的一些思考

为了促进我国工程建设管理由粗放式向科学化、规范化管理的转变,国家针对影响工程建设管理的几个关键环节,提出了“四制”:为了明确管理主体责任,实行了项目法人负责制;为了引进市场竞争机制,实行了招标投标制;为了实现工程质量全面专业化管理,实行了建设监理制;为了规范工程建     

Service composition for generic service graphs

Service composition is a promising approach to multimedia service provisioning, due to its ability to dynamically produce new multimedia content, and to customize the content for individual client devices. Previous research work has addressed various aspects of service composition such as composibility, QoS-awareness, and load balancing. However, most of the work has focused on applications where data flow from a single source is processed by intermediate services and then delivered to a single destination. In this paper, we address the service composition problem for multimedia services that can be modeled as directed acyclic graphs (DAGs). We formally define the problem and prove its NP hardness. We also design a heuristic algorithm to solve the problem. Our simulation results show that the algorithm is effective at finding low-cost composition solutions, and can trade off computation overhead for better results. When compared with a hop-by-hop approach for service composition, our algorithm can find composition solutions that aress 10% smaller in cost, even when the hop-by-hop approach uses exhaustive searches.     

实时操作系统DSP/BIOS在DSP开发中的应用

本文介绍了RTOS(实时操作系统)DSP／BIOS在DSP的开发设计中的应用。在简述了DSP的一般模型后，论述了RTOS在DSP／BIOS外设管理，实时性能分析以及程序流程控制中的应用。     

Windows2000设备驱动程序即插即用的实现

概述了Windows2000即插即用系统组成及其实现过程,结合实例介绍了Windows2000设备驱动程序如何支持用户即插即用的功能。