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Search Results: 1 - 10 of 3239 matches for " Shiguang Shang "
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A High-Luminescence Fringelike Field Emission from Screen-Printed Carbon Nanotube and Zinc Oxide Composite Film  [PDF]
Shiguang Shang, Ling Zhao, Weihua Liu, Ping Zhao, Xin Li
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.212085
Abstract: A fringelike field emission with high-luminescence and stable emission current from screen-printed carbon nanotube mixed zinc oxide (CNT-ZnO) composite cathode was investigated. The luminescent patterns are significantly different from those observed in the field emission measure of pure CNT cathode. SEM images reveal that the CNTs are perfectly matched with ZnO powders by filling the interspaces in CNT film. XRD analysis demonstrates that the CNTs and ZnO have a high degree of crystalline perfection. Field emission measurement exhibits that the turn-on field of CNT-ZnO cathode is 2.08 V/µm, lower than 2.46 V/µm for pure CNT cathode. The large fringelike emission current at the brims of CNT-ZnO cathode is attributed to a combination of the increased effective contact area of CNTs, which decrease the sheet resistance of cathode film, and the dangled CNT bundles at the brims of CNT-ZnO film cathode.
Uniqueness of the Foliation of Constant Mean Curvature Spheres in Asymptotically Flat 3-Manifolds
Shiguang Ma
Mathematics , 2010,
Abstract: In this paper I study the constant mean curvature surface in asymptotically flat 3-manifolds with general asymptotics. Under some weak condition, I prove that outside some compact set in the asymptotically flat 3-manifold with positive mass, the foliation of stable spheres of constant mean curvature is unique.
On the radius pinching estimate and uniqueness of the CMC foliation in asymptotically flat 3-manifolds
Shiguang Ma
Mathematics , 2012,
Abstract: In this paper we consider the uniqueness problem of the constant mean curvature spheres in asymptotically flat 3-manifolds. We require the metric have the form g_{ij}=\delta_{ij}+h_{ij} with h_{ij}=O_{4}(r^{-1}) and R=O(r^{-3-\tau}),\tau>0. We do not require the metric to be close to Schwarzschild metric in any sense or to satisfy RT conditions. We prove that, when the mass is not 0, stable CMC spheres that separate a certain compact part from infinity satisfy the radius pinching estimate r_{1}\leq Cr_{0} , which in many cases is critical to prove the uniqueness of the CMC spheres. As applications of this estimate, we remove the radius conditions of the uniqueness result in [Huang-CMC] and [NERZ-CMC] in some special cases.
Unstable CMC spheres and outlying CMC spheres in AF 3-manifolds
Shiguang Ma
Mathematics , 2015,
Abstract: In this paper, we introduce a non linear ODE method to construct CMC surfaces in Riemannian manifolds with symmetry. As an application we construct unstable CMC spheres and outlying CMC spheres in asymptotically Schwarzschild manifolds with metrics like $g_{ij}=(1+\frac{1}{l})^{2}\delta_{ij}+O(l^{-2})$. The existence of unstable CMC spheres tells us that the stability condition in Qing-Tian's work [Qing-Tian-CMC] can not be removed generally.
A Novel Method to Implement Book Cipher
Changda Wang,Shiguang Ju
Journal of Computers , 2010, DOI: 10.4304/jcp.5.11.1621-1628
Abstract: Armed with super computational ability, the most efficient attack on symmetric-key systems is an exhaustive key search. A novel encryption method with infinite key space is presented by modifying traditional book cipher. Infinite key space means the unbounded entropy of the key space, which can frustrate any exhaustive key search. Moreover, this book cipher is immune from frequency analysis. Experimental results show that both encryptionand decryption have very high rates of data throughput while compared with DES. High efficiency makes it suitable for some computing power limited environments.
Covert Flow Graph Approach to Identifying Covert Channels
XiangMei Song,ShiGuang Ju
Journal of Networks , 2011, DOI: 10.4304/jnw.6.12.1740-1746
Abstract: In this paper, the approach for identifying covert channels using a graph structure called Covert Flow Graph is introduced. Firstly, the construction of Covert Flow Graph which can offer information flows of the system for covert channel detection is proposed, and the search and judge algorithm used to identify covert channels in Covert Flow Graph is given. Secondly, an example file system analysis using Covert Flow Graph approach is provided, and the analysis result is compared with that of Shared Resource Matrix and Covert Flow Tree method. Finally, the comparison between Covert Flow Graph approach and other two methods is discussed. Different from previous methods, Covert Flow Graph approach provides a deep insight for system’s information flows, and gives an effective algorithm for covert channel identification.
Constant mean curvature surfaces of Delaunay type along a closed geodesic
Shiguang Ma,Frank Pacard
Mathematics , 2014,
Abstract: In this paper, we construct Delaunay type constant mean curvature surfaces along a non degenerate closed geodesic in a 3-dim Riemannian manifold.
More on Descriptive Complexity of Second-Order HORN Logics
Shiguang Feng,Xishun Zhao
Computer Science , 2014,
Abstract: This paper concerns Gradel's question asked in 1992: whether all problems which are in PTIME and closed under substructures are definable in second-order HORN logic SO-HORN. We introduce revisions of SO-HORN and DATALOG by adding first-order universal quantifiers over the second-order atoms in the bodies of HORN clauses and DATALOG rules. We show that both logics are as expressive as FO(LFP), the least fixed point logic. We also prove that FO(LFP) can not define all of the problems that are in PTIME and closed under substructures. As a corollary, we answer Gradel's question negatively.
Positioning a Node of Wireless Sensor Networks in 3 Dimensional Space  [PDF]
Wenhui NIE, Shiguang JU, Anrong XUE, Feng LI
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.26059
Abstract: To know the location of nodes is very important and valuable for wireless sensor networks (WSN), we present an improved positioning model (3D-PMWSN) to locate the nodes in WSN. In this model, grid in space is presented. When one tag is detected by a certain reader whose position is known, the tag’s position can be known through certain algorithm. The error estimation is given. Emulation shows that the positioning speed is relatively fast and positioning precision is relatively high.
The Latest Progress of the Conceptual Framework  [PDF]
Ting Shang
Modern Economy (ME) , 2015, DOI: 10.4236/me.2015.66065
Abstract: During the past 30 years, the world’s economy developed rapidly, but the formulation of accounting standards often could not keep up with the pace of economic development as the continuous innovation of financial instruments or derivatives financial instruments, the increasingly frequency of unconventional activities such as merger, acquisition and restructuring, the rapid flowing of global capital, and the development of networking, information science and technology. Thus the lagging and patching method of accounting standards made the conceptual framework which was ever explored in the past back to the IASB agenda again. This paper mainly described the latest progress of the conceptual framework after IASB released Discussion Paper, analyzed the characteristics of the restatement of CF, and proposed several thoughts for the China CF and accounting standards.
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