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Experimental Research on a Hypersonic Configuration with Blunt Forebody Edges
Xiao, Hong,Xu, Zhe-Zhu,Kim, Lae-Sung,Li, Dong-yang,Lyu, Sung-Ki Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.10
A design method, for hypersonic forebody configuration with blunt edges, was developed by lift body and waverider. Experimental study was conducted. It was showed that the difference of pressure coefficient, at centre-line and side-line on forebody pre-compression surface, was between 2.5% and 16.7% within the Mach number 5 to 7 and attack angle 0 to 12. These differences were slightly bigger than those of non-blunt-edges forebody. However, experimental data also show that the present configuration can achieve the closed shockwave, and can also realize the automatic overflow of boundary layer on forebody pre-compression surface. It is also observed that the present forebody gets a good aerodynamic performance at high Mach numbers. But with increasing attack angle, the advantage was weakened gradually. And, at the degree of side-slip exceeding 8, the side-line pressure is higher than that of center-line, which indicates that the forebody boundary layer does not achiev automatically overflowing to side surface.
A Unified Threat Model for Assessing Threat in Web Applications
Xiaohong Li,Ke He 보안공학연구지원센터 2008 International Journal of Security and Its Applicat Vol.2 No.3
This paper presents a unified threat model for assessing threat in web applications. We extend the threat tree model with more semantic and context information about threat to form the new model which is used to analyze and evaluate threat in the software design stage. We utilize historical statistical information contained in this model to design threat mitigation schemes. The threat assessing results and mitigation schemes can be used to direct secure coding and testing. This makes it possible to design threat-resistant web applications by means of detecting and mitigating threat in the early software design stage.
Xiaohong Xiao,Shimon Wdowinski,Yonggang Wu 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.11
The aim of this study is to extract water body using the integrated features of Landsat ETM+ and ALOS PALSAR data. Water body extracted from Landsat ETM+ tends to lose smaller water bodies like small rivers and ponds. Besides, water area with plant (lotus) is difficult to recognize. ALOS PALSAR data have a much higher resolution, capable of extracting almost all the water bodies without confusion with other surface features, but leave some holes in water bodies due to its speckles. As a consequence, there is a significant interest in the development of fusion methods that are able to take advantage of the complementary nature of Landsat ETM+ and ALOS PALSAR data. A new combination method of integrating band 3, band 7 of Landsat ETM+ with a modified HH polarization of ALOS PALSAR is proposed, which well combine the complementary water information from each source compared to the standard image fusion methods. Experimental outcomes of the proposed combination B37ModHH shows great enhancement in water classification accuracy compared to Landsat ETM+ and ALOS PALSAR alone.
Xiaohong Jiao,Xin Li,Zhisong Mei 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In view of the case that time-delay arises in the output measurements and the states are not all measurable in practical engineering control, the robust output feedback stabilization problem is investigated for a class of nonlinear time-delay systems in the presence of delayed output measurement. First, based on Lyapunov-Krasovskii functional stability theory, a sufficient condition is given under which the whole system consisting of the original system and the feedback controller with the observer is robust asymptotically stable at the equilibrium, moreover, the feedback gain and the observer gain can be obtained. And then, by employing the result presented, the robust stabilization problem is solved for the hydraulic automatic gauge control (HAGC) system in a cold strip rolling mill. It is shown under the case that the instrumentation used only is the thickness meter, there exists a delay-independent dynamic output feedback robust controller such that the roll gap, the depress force of the hydraulic cylinder and the strip exit thickness all can be regulated to their desired set values regardless of the nonlinearity and uncertainty in the dynamic descriptions of the system as well as the output time-delay in the measurement. Finally, the simulation results are given to show the effectiveness of the proposed control scheme.
Stability and optimal control of microorganisms in continuous culture
Xiaohong Li,Enmin Feng,Zhilong Xiu 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.22 No.1-2
The process of producing 1,3-preprandiol by microorganism continuous cultivation would attain its equilibrium state. How to get the highest concentration of 1,3-propanediol at that time is the aim for producers. Based on this fact, an optimization model is introduced in this paper, existence of optimal solution is proved. By infinite-dimensional optimal theory, the optimal condition of model is given and the equivalence between optimal condition and the zero of optimality function is proved.
Weyl spectrum of the products of operators
Xiaohong Cao 대한수학회 2008 대한수학회지 Vol.45 No.3
Let MC = (수식) be a 2×2 upper triangular operator matrix acting on the Hilbert space H K and let σw(ㆍ) denote theWeyl spectrum. We give the necessary and sufficient conditions for operators A and B which [수식] holds for every C ∈ B(K, H). We also study the Weyl’s theorem for operator matrices. Let MC = (수식) be a 2×2 upper triangular operator matrix acting on the Hilbert space H K and let σw(ㆍ) denote theWeyl spectrum. We give the necessary and sufficient conditions for operators A and B which [수식] holds for every C ∈ B(K, H). We also study the Weyl’s theorem for operator matrices.
A finite difference scheme for RLW-Burgers equation
Xiaohong Zhao,Desheng Li,Deming Shi 한국전산응용수학회 2008 Journal of applied mathematics & informatics Vol.26 No.3-4
In this paper, a finite difference method for a Cauchy problem of RLW-Burgers equation was considered. Although the equation is not energy conservation, we have given its the energy conservative finite difference scheme with condition. Convergence and stability of the difference solution were proved. Numerical results demonstrate that the method is efficient and reliable. In this paper, a finite difference method for a Cauchy problem of RLW-Burgers equation was considered. Although the equation is not energy conservation, we have given its the energy conservative finite difference scheme with condition. Convergence and stability of the difference solution were proved. Numerical results demonstrate that the method is efficient and reliable.
Analysis of South Korea's Direct Investment in China
Xiaohong Zhan Jungseok Research Institute of International Logis 2004 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.2 No.2
Using a dynamic perspective this article examines, the general situation of the development of south Korean direct investment in China since 1992, when the two countries established diplomatic relations. It probes many characteristics of South Korean direct investment in China; its late start yet rapid rise; the smaller average value of Korean project investments; the accelerated process of localization by large South Korean enterprises in China; the diversified industrial distribution; and the wide-ranging geographical distribution. It analyses the reasons for the rapid increase in South Korean investment in China: the use of china's low-priced production factors, the direct entry of South Korean enterprises into the Chinese market, and the stable investment environment with fewer labor disputes that China provides. Finally, this article also proves that south Korean enterprises have achieved satisfactory results from their direct investment in China.