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Search Results: 1 - 10 of 65709 matches for " XU Cheng "
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A Study on Chinese Regional Scientific Innovation Efficiency with a Perspective of Synergy Degree  [PDF]
Lixin Xu, Min Cheng
Technology and Investment (TI) , 2013, DOI: 10.4236/ti.2013.44027
Abstract: From the perspective of the process of regional scientific innovation, the regional scientific innovation system is divided into two sub-systems of technology output and economic output. We utilize the chain-DEA method to assess scientific innovation and each sub-system’s efficiencies of 30 Chinese provinces from 2001 to 2011. Results suggest that the scientific innovation and each sub-system’s efficiencies need to be improved, unequilibrium in different regions exists evidently, each sub-system efficiency of one district varies a lot and the synergy degree remains low. Next, we compute the synergy degree of the two sub-systems using the synergy degree model. By employing linear regression model, an obvious positive correlation is demonstrated between the synergy and the scientific innovation efficiency. At last, based on the results of this study and real situations of Chinese scientific innovation, some suggestions are put forward accordingly.
On the Origin of Early Jade Dagger-Axe: A Brief Analysis  [PDF]
Cheng Xue, Yingzhi Xu
Archaeological Discovery (AD) , 2017, DOI: 10.4236/ad.2017.53011
Abstract: The jade dagger-axe is a significant ritual artifact in prehistoric China and therefore has been the subject of much discussion among archaeologists and historians. The authors compare the jade dagger-axe and the axe in terms of the morphological features, the means of hafting, and the use in burial ritual. It appears that the shape of the jade dagger-axe is the result of improving the axe. The means of hafting the jade dagger-axe is generally identical to that of the axe. The ritualization of the jade dagger-axe follows that of the axe. Therefore, the jade dagger-axe may have originated from the axe.
Yamabe invariant for complete manifold with nonpositive scalar curvature
Xu Cheng
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02883373
Abstract: A sufficient condition for Yamabe invariants to be non-positive and its applications are obtained.
An almost-Schur type lemma for symmetric $(2,0)$ tensors and applications
Xu Cheng
Mathematics , 2012,
Abstract: In our previous paper in \cite{C}, we generalized the almost-Schur lemma of De Lellis and Topping for closed manifolds with nonnegative Rcci curvature to any closed manifolds. In this paper, we generalize the above results to symmetric $(2,0)$-tensors and give the applications including $r$th mean curvatures of closed hypersurfaces in a space form and $k$ scalar curvatures for closed locally conformally flat manifolds.
A QoE Assessment System in Distance Education  [PDF]
Dengyin Zhang, Yangyang Xu, Chunling Cheng
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.31011
Abstract: It is a challenging task to improve the real-time property and objectivity of the effect assessment for the distance education. This paper presents a QoE (Quality of Experience) assessment system based on the attention of online user. The system captures the video frames from two cameras periodically and synchronously, using the adaptive image binarization based on the linear average threshold for the pretreatment, then processing with edge detection and filtering in the cross-directions at the same time. System gets the position of computer screen and user eyeball. Analyzing the detection results comprehensively obtains the attention of online user by some judging conditions, and finally acquires the quality of user experience. Experimental results demonstrate the feasibility and efficiency.
Context-Based Mobile User Interface  [PDF]
Mao Zheng, Sihan Cheng, Qian Xu
Journal of Computer and Communications (JCC) , 2016, DOI: 10.4236/jcc.2016.49001
Abstract: Context awareness is increasingly gaining applicability in interactive ubiquitous mobile computing systems. Each context-aware application has its own set of behaviors to react to context modifications. Hence, every software engineer needs to clearly understand the goal of the development and to categorize the context in the application. We incorporate context-based modifications into the appearance or the behavior of the interface, either at the design time or at the run time. In this paper, we present application behavior adaption to the context modification via a context-based user interface in a mobile application. We are interested in a context-based user interface in a mobile device that is automatically adapted based on the context information. We use the adaption tree, named in our methodology, to represent the adaption of mobile device user interface to various context information. The context includes the user’s domain information and dynamic environment changes. Each path in the adaption tree, from the root to the leaf, presents an adaption rule. An e-commerce application is chosen to illustrate our approach. This mobile application was developed based on the adaption tree in the Android platform. The automatic adaption to the context information has enhanced human-computer interactions.
Condensation Heat Transfer with Non-Condensable Gas on a Vertical Tube  [PDF]
Shengjun Zhang, Xu Cheng, Feng Shen
Energy and Power Engineering (EPE) , 2018, DOI: 10.4236/epe.2018.104B004
A novel passive containment cooling system (PCCS) is proposed to be installed in the advanced nuclear reactor to cope with LOCA and MSLB accident. The internal heat exchanger is located inside the containment and the condensation heat transfer characteristic outside the tube determines the performance of the system. An improved model based on heat and mass transfer is presented to predict the heat and mass transfer accompanying with condensation. Different with Dehibi’s model, the liquid film conduction is considered and the interface temperature is solved by iteration. The results show the effect of different parameter on heat transfer coefficient. And the correlation can well predict the experiment data.
An Energy-aware Hierarchical Architecture Design Scheme  [PDF]
Linfeng YUAN, Yang XU, Xu DU, Wenqing CHENG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2008, DOI: 10.4236/ijcns.2008.11009
Abstract: Compared with the flat architecture in the design of sensor networks, the hierarchical architecture gains much attractive for the reason of scalability, management and energy efficiency. In order to distribute the energy evenly, nodes act the cluster head in some orders. The existing approaches don’t pay a critical attention to the overhead during the role rotations. And the duration of a round is a priori, which is very application-specific. An energy-aware hierarchical architecture design scheme is put forward in this paper, namely, Adaptive Minimum Rotational Cost (AMRC) cluster formation scheme. The decision of beginning a new round is made adaptively by the cluster head itself. It combines the dynamic and static advantages in the clustering architecture. The simulation results demonstrate AMRC outperforms some other clustering protocols in many aspects.
Nonparametric Confidence Limits of Quantile-Based Process Capability Indices
Cheng Peng,Jiaqing Xu
International Journal of Quality, Statistics, and Reliability , 2012, DOI: 10.1155/2012/985152
Abstract: We propose an asymptotic nonparametric confidence interval for quantile-based process capability indices (PCIs) based on the superstructure (,) modified from (,) which contains the four basic PCIs, , , , and , as special cases. Since the asymptotic variance of the estimator for quantile-based PCIs involves the density function of the underlying process, the existing asymptotic results cannot be used directly to construct confidence limits for PCIs. To obtain a consistent estimator for the asymptotic variance of the estimated quantile-based PCIs, in this paper, we propose to use the kernel density estimator for the underlying process. Consequently, the confidence limits for PCIs are established based on the consistent estimates. A real-life example from manufacturing engineering is used to illustrate the implementation of the proposed methods. Simulation studies are also presented in this paper to compare the two quantile estimators that are used in the definition of PCIs.
Embedded positive constant r-mean curvature hypersurfaces in Mm × R
Cheng, Xu;Rosenberg, Harold;
Anais da Academia Brasileira de Ciências , 2005, DOI: 10.1590/S0001-37652005000200001
Abstract: let m be an m-dimensional riemannian manifold with sectional curvature bounded from below. we consider hypersurfaces in the (m + 1)-dimensional product manifold m × r with positive constant r-mean curvature. we obtain height estimates of certain compact vertical graphs in m × r with boundary in m × {0}. we apply this to obtain topological obstructions for the existence of some hypersurfaces. we also discuss the rotational symmetry of some embedded complete surfaces in s2 × r of positive constant 2-mean curvature.
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