Out of plane effect on the superconductivity of Sr2-xBaxCuO3+y with Tc up to 98K

A series of new Sr2-xBaxCuO3+y (0 x 0.6) superconductors were prepared using high-pressure and high-temperature synthesis. A Rietveld refinement based on powder x-ray diffraction confirms that the superconductors crystallize in the K2NiF4-type structure of a space group I4/mmm similar to that of La2CuO4 but with partially occupied apical oxygen sites. It is found that the superconducting transition temperature Tc of this Ba substituted Sr2CuO3+y superconductor with constant carrier doping level, i.e., constant d, is controlled not only by order/disorder of apical-O atoms but also by Ba content. Tcmax =98 K is achieved in the material with x=0.6 that reaches the record value of Tc among the single-layer copper oxide superconductors, and is higher than Tc=95K of Sr2CuO3+y with optimally ordered apical-O atoms. There is Sr-site disorder in Sr2-xBaxCuO3+y which might lead to a reduction of Tc. The result indicates that another effect surpasses the disorder effect that is related either to the increased in-plane Cu-O bond length or to elongated apical-O distance due to Ba substitution with larger cation size. The present experiment demonstrates that the optimization of local geometry out of the Cu-O plane can dramatically enhance Tc in the cuprate superconductors.Comment: 23 Pages, 1 Table, 5 Figure

A New Method for Determining the Anisotropic Parameters of Materials Under True Triaxial Cyclic Loading

In this paper a new approach to solving the basic equations of elastic cross-anisotropic stress and strain relationships is presented. The uniqueness of the equations is demonstrated and the conditions for their use are easily controlled in the true triaxial test equipment available in the laboratory. By this approximate solution the four anisotropic parameters of cross-anisotropic materials can be obtained. In addition, so-called fuzzy logic weighting factors are introduced to assess the differences among the observed principal deformations of samples tested. A computer program ANISOLV has been written to calculate the formulated parameters. Some typical examples are given to demonstrate the reliability and validity of the method and the program

A 3-D security modeling platform for social IoT environments

Social Internet-of-Things (SIoT) environment comprises not only smart devices but also the humans who interact with these IoT devices. The benefits of such system are overshadowed due to the cyber security issues. A novel approach is required to understand the security implication under such a dynamic environment while taking both the social and technical aspects into consideration. This paper addressed such challenges and proposed a 3-D security modeling platform that can capture and model the security requirements in the SIoT environment. The modeling process is graphical notation based and works as a security extension to the Business Process Model and Notation. Still, it utilizes the latest 3-D game technology; thus, the security extensions are generated through the third dimension. Consequently, the introduction of security extensions will not increase the complexity of the original SIoT scenario, while keeping all the key information on the same platform. Together with the proposed security ontology, these comprehensive security notations created a unique platform that aims at addressing the ever complicated security issues in the SIoT environment

Parallel Computing on a PC Cluster

The tremendous advance in computer technology in the past decade has made it possible to achieve the performance of a supercomputer on a very small budget. We have built a multi-CPU cluster of Pentium PC capable of parallel computations using the Message Passing Interface (MPI). We will discuss the configuration, performance, and application of the cluster to our work in physics.Comment: 3 pages, uses Latex and aipproc.cl