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Li Y.,National University of Defense Technology | Chen S.,National University of Defense Technology | Ma X.,University of Science and Technology Beijing | Hu H.,National University of Defense Technology | Zhang Y.,PLA Xuzhou Air force College
Journal of Alloys and Compounds | Year: 2017

The preparation temperature for C/ZrC composites was optimized by assessing the effects on their mechanical and ablation properties. The composites were prepared by precursor infiltration and pyrolysis at 1500 °C, 1550 °C and 1600 °C. With rising preparation temperature, the open porosity of the composites increased, accompanied by formation of a strong interface and aggravated damage to carbon fibers, which were adverse to the mechanical properties. As a result, the flexural strength and fracture toughness decreased from 232 MPa to 11.9 MPa m1/2 to 103 MPa and 3.4 MPa m1/2 respectively. Meanwhile, elevating the open porosity provided more passage for oxygen into C/ZrC composites, which weakened the ablation resistance. The linear recession rate increased from 21.0 μm/s to 32.0 μm/s and then to 35.7 μm/s. Taking mechanical and ablation properties into consideration simultaneously, the optimum preparation temperature was 1500 °C. © 2016 Elsevier B.V.

Deng J.,Shanghai JiaoTong University | Deng J.,PLA Xuzhou Air force College | Wang R.Z.,Shanghai JiaoTong University | Han G.Y.,PLA Xuzhou Air force College
Progress in Energy and Combustion Science | Year: 2011

The state of the art of research in thermally activated cooling technologies for combined cooling, heating and power (CCHP) systems are presented here in detail, mainly including absorption and adsorption refrigeration, and desiccant cooling. A basic description of thermally activated cooling is given first. Next, according to the diverse categories of thermally activated cooling, the working principles, products markets available or under development, diverse combinations of thermally activated technologies in CCHP applications or experimental units, and existing problems are listed and discussed through a comprehensive review of the literature. Furthermore, more recent advanced research of thermally activated cooling in innovative concept, material and technologies are included. Finally, detailed summary and suggestions are proposed for proper utilization of thermally activated cooling technologies, and the future development roadmap and preferred strategies are also outlined. The review will demonstrate that thermally activated cooling technologies are attractive alternatives that not only serve the need for air-conditioning, refrigeration, dehumidification, and augmenting prime movers, but also can meet the demand for energy conservation and environmental protection. © 2010 Elsevier Ltd. All rights reserved.

Xu Q.,Tsinghua University | Xu Q.,PLA Xuzhou Air force College | Zhang X.,Tsinghua University
PLoS ONE | Year: 2016

The assumption that total abundance of RNAs in a cell is roughly the same in different cells is underlying most studies based on gene expression analyses. But experiments have shown that changes in the expression of some master regulators such as c-MYC can cause global shift in the expression of almost all genes in some cell types like cancers. Such shift will violate this assumption and can cause wrong or biased conclusions for standard data analysis practices, such as detection of differentially expressed (DE) genes and molecular classification of tumors based on gene expression. Most existing gene expression data were generated without considering this possibility, and are therefore at the risk of having produced unreliable results if such global shift effect exists in the data. To evaluate this risk, we conducted a systematic study on the possible influence of the global gene expression shift effect on differential expression analysis and on molecular classification analysis. We collected data with known global shift effect and also generated data to simulate different situations of the effect based on a wide collection of real gene expression data, and conducted comparative studies on representative existing methods. We observed that some DE analysis methods are more tolerant to the global shift while others are very sensitive to it. Classification accuracy is not sensitive to the shift and actually can benefit from it, but genes selected for the classification can be greatly affected. © 2016 Xu, Zhang.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Li H.,PLA Xuzhou Air force College
Proceedings - 7th International Conference on Intelligent Information Hiding and Multimedia Signal Processing, IIHMSP 2011 | Year: 2011

Bipedal robot is constituted of leg, waist platform, upper body, arms, head and several other parts, all the parts are connected by highly precise connecting part. The robot can realize 23 degrees of freedom and simulate several kinds of sports of human body, which is realized by 23 high-precision big torque servo motor. Legs with eight degrees of freedom are multi-pole system with non-closed rotary joint connecting together. Combined with multiple high-precision pressure sensors, it can achieve high precision walking in the self-adjusting and guarantee the stability of walking. It laids the foundation of application for intelligent robot in the future industry. © 2011 IEEE.

Zhang J.G.,Shanghai Institute of Technology | Deng J.,PLA Xuzhou Air force College
Polymer - Plastics Technology and Engineering | Year: 2011

The friction and wear properties of polyamide6 (PA6), polyamide6/carbon nanotube (PA6/CNT) nanocomposites and PA6/maleic anhydride grafted Styrene-ethylene-butylene-styrene (SEBS-g-MA+CNT) nanocomposites was studied by means of a ring-on-block tribometer. The morphologies of the worn surfaces of specimens were observed with a scanning electron microscopy (SEM). All specimen wear increases with increasing load; meanwhile, the friction coefficient decreases. Wear of PA6/CNT is larger than that of PA6. Adding SEBS-g-MA to the PA6/CNT improves the wear resistance. The friction coefficient of PA6/CNT is slightly less than that of PA6 at various loads. The friction coefficient of PA6/(SEBS-g-MA+CNT) is the lowest among PA6, PA6/CNT and PA6/(SEBS-g-MA+CNT). © 2011 Copyright Taylor and Francis Group, LLC.

Zhang M.,Nanjing University | Zhang M.,PLA Xuzhou Air force College | Luo W.,Nanjing University | Li Z.,Nanjing University | And 2 more authors.
Applied Physics Letters | Year: 2010

We studied photoelectrochemical performance of the undoped, Si-doped, Ti-doped, and codoped α -Fe2O3 film prepared by ultrasonic spray pyrolysis. Since the ions radius of Si4+ < Fe3+ < Ti4+, Si and Ti codoping can balance the ion radius difference between Fe3+ and Si4+ (or Ti 4+) and increase the donor concentration. Their donor concentrations, calculated from slopes of the Mott-Schottky plots, are 9.10× 10 18 cm-3, 1.89× 1020 cm-3, 2.04× 1020 cm-3, and 7.06× 1020 cm-3, respectively. Incident photon to current efficiency of the codoped film is 34% at 365 nm and 0.6 V versus Ag/AgCl, much higher than 10%, 20%, and 22% for the undoped, Si-doped, and Ti-doped film, respectively. © 2010 American Institute of Physics.

Li T.,PLA Xuzhou Air force College
Applied Mechanics and Materials | Year: 2012

The electronic structures and optical linear response functions of ZnO are calculated. The relationships between electronic structures and optical properties are investigated by using first-principles based upon the density functional theory. The dielectric functions, reflection spectra,refractive index and of ZnO dominated by electron inter-band transitions are analyzed interms of the precisely calculated band structure and Conductivity density of state. Furthermore, we analyzed the change of electron structure, bonding and optical properties after doping in comparison with the experimental results. The theoretical results offering theoretical data for the design and application of optoelectronic materials of ZnO. Meanwhile, the calculated results also enable more precise monitoring and controlling during the growth of ZnO material.

Hou J.Y.,PLA Xuzhou Air force College
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010 | Year: 2010

It's an introduction for Ad Hoc Network's concept, characteristics, fields of applications and routing methods. It provides a universal simulation framework with the support of OPNET, which is in the purpose of testing different MAC layer, network layer, and the router's efficiency of mobile Ad Hoc network which is in the characteristic of mobile node. Backed up by layered integral framework, it is possible to design various modes of mobile node, methods for jointing Medias and routing scheme. Therefore we can compare statistic in different ends, which is in the aim of selecting the most effective and the most suitable resolving project. This design brings a great improvement in routing overhead, end-to-end packet delay, transfer rate etc. © 2010 IEEE.

Dai J.,North China Institute of Aerospace Engineering | Guo Z.,North China Institute of Aerospace Engineering | Wang S.,PLA Xuzhou Air force College
Circuits, Systems, and Signal Processing | Year: 2013

This paper is concerned with the problem of stability and robust H ∞ control for 2-D stochastic systems with parameter uncertainties and sector nonlinearities. The class of systems under investigation is described by the 2-D state-space Roesser model. Our attention is focused on the design of a state feedback controller for 2-D stochastic system with sector nonlinearity, such that the closed-loop 2-D stochastic system is asymptotically stable and has a prescribed H ∞ disturbance attenuation performance. First, a sufficient condition is established for the 2-D nonlinear stochastic systems to be asymptotically stable. Then, we extend the bounded real lemma for 2-D systems to 2-D stochastic systems with sector nonlinearities. Based on this lemma, solvability conditions for the H ∞ control of 2-D nonlinear stochastic systems in the form of LMIs (linear matrix inequalities) are derived. A numerical example illustrates the effectiveness of the proposed results. © 2013 Springer Science+Business Media New York.

Zhang X.,PLA Xuzhou Air force College | Wang T.,PLA Xuzhou Air force College | Jia L.,PLA Xuzhou Air force College
Applied Mechanics and Materials | Year: 2014

In this paper, we put forward a differential service-oriented and self-adaptive job scheduling system in Cloud Computing environment. Analysis and number results show that our approach for job scheduling system can not only guarantee the QoS requirements of the CCU's jobs, but also can make the maximum profits for the CCSP. To the best of our knowledge, the job scheduling system in our paper maybe the first paper to consider both the QoS requirement of jobs and Cloud Computing service providers' profits. © (2014) Trans Tech Publications, Switzerland.

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