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Search Results: 1 - 10 of 93562 matches for " Jie Liu "
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The Enterprise Risk Management and the Risk Oriented Internal Audit  [PDF]
Jie Liu
iBusiness (IB) , 2012, DOI: 10.4236/ib.2012.43036
Abstract: With the development of the economic globalization, the risks that enterprises faced are increasing. In order to cope with the risks, the enterprise risk management requires the internal audit. As an important part of the internal control, the risk oriented internal audit emerges to monitor the process of the enterprise risk management. So enterprises can control and evaluate the risks more and more suitable. The research focused on the importance of the risk oriented internal audit, and also studied the status of our risk oriented audit, then the research proposed some strategies and suggestions to promote the application of the risk oriented internal audit so as to ensure the effectiveness of the enterprise risk management.
A Distributed Compressed Sensing for Images Based on Block Measurements Data Fusion  [PDF]
Huaixin Chen, Jie Liu
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.512B026
Abstract: Compressed sensing (CS) is a new technique for simultaneous data sampling and compression. In this paper, we propose a novel method called distributed compressed sensing for image using block measurements data fusion. Firstly, original image is divided into small blocks and each block is sampled independently using the same measurement operator, to obtain the smaller encoded sparser coefficients and stored measurements matrix and its vectors.  Secondly, original image is reconstructed using the block measurements fusion and recovery transform. Finally, several numerical experiments demonstrate that our method has a much lower data storage and calculation cost as well as high quality of reconstruction when compared with other existing schemes. We believe it is of great practical potentials in the network communication as well as pattern recognition domain.
Research on the Arrangement of Dew Point Temperature Detectors of Capillary Plane Radiation Air-Conditioning  [PDF]
Xuelai Liu, Jie Wu
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.24012
Abstract: Based on analysis of the reason and process of condensation on ceiling radiant cooling panels, two kinds of arrangement of detectors are put forward. The physical model is established, the results show that detectors are arranged as the form of triangle is more suitable. It can not only satisfy the use requirement but also it is economical and practical. Finally we can conclude that the inlet water temperature 0.5°C higher than dew point temperature is safe and reliable.

Analytical Calculation of the Compton Single Scatter Component of Pencil Beam Scatter Kernel for Scatter Correction in kV Cone Beam CT (kV-CBCT)  [PDF]
Jie Liu, J. Daniel Bourland
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2018, DOI: 10.4236/ijmpcero.2018.72019

The accuracy of conventional superposition or convolution methods for scatter correction in kV-CBCT is usually compromised by the spatial variation of pencil-beam scatter kernel (PBSK) due to finite size, irregular external contour and heterogeneity of the imaged object. This study aims to propose an analytical method to quantify the Compton single scatter (CSS) component of the PBSK, which dominates the spatial distribution of total scatter assuming that multiple scatter can be estimated as a constant background and Rayleigh scatter is the secondary source of scatter. The CSS component of PBSK is the line integration of scatter production by incident primary photons along the beam line followed by the post-scattering attenuation as the scattered photons traverse the object. We propose to separate the object-specific attenuation term from the line integration and equivalently replace it with an average value such that the line integration of scatter production is object independent but only beam specific. We derived a quartic function formula as an approximate solution to the spatial distribution of the unattenuated CSS component of PBSK. The “effective scattering center” is introduced to calculate the average attenuation. The proposed analytical framework to calculate the CSS was evaluated using parameter settings of the On-Board Imager kV-CBCT system and was found to be in high agreement with the reference results. The proposed method shows highly increased computational efficiency compared to conventional analytical calculation methods based on point scattering model. It is also potentially useful for correcting the spatial variant PBSK in adaptive superposition method.

Searching for dark matter isocurvature initial conditions with N-body Simulations
Jie Liu
Physics , 2011, DOI: 10.1142/S0218271812500216
Abstract: Small fraction of isocurvature perturbations may exist and correlate with adiabatic perturbations in the primordial perturbations. Naively switching off isocurvature perturbations may lead to biased results. We study the effect of dark matter isocurvature on the structure formation through N-body simulations. From the best fit values, we run four sets of simulation with different initial conditions and different box sizes. We find that, if the fraction of dark matter isocurvature is small, we can not detect its signal through matter power spectrum and two point correlation function with large scale survey. However, the halo mass function can give an obvious signal. Compared to 5% difference on matter power spectrum, it can get 37% at $z = 3$ on halo mass function. This indicates that future high precise cluster count experiment can give stringent constraints on dark matter isocurvature perturbations.
Combined field formulation and a simple stable explicit interface advancing scheme for fluid structure interaction
Jie Liu
Mathematics , 2013,
Abstract: We develop a combined field formulation for the fluid structure (FS) interaction problem. The unknowns are (u;p;v), being the fluid velocity, fluid pressure and solid velocity. This combined field formulation uses Arbitrary Lagrangian Eulerian (ALE) description for the fluid and Lagrangian description for the solid. It automatically enforces the simultaneous continuities of both velocity and traction along the FS interface. We present a first order in time fully discrete scheme when the flow is incompressible Navier-Stokes and when the solid is elastic. The interface position is determined by first order extrapolation so that the generation of the fluid mesh and the computation of (u;p;v) are decoupled. This explicit interface advancing enables us to save half of the unknowns comparing with traditional monolithic schemes. When the solid has convex strain energy (e.g. linear elastic), we prove that the total energy of the fluid and the solid at time t^{n} is bounded by the total energy at time t^{n-1}. Like in the continuous case, the fluid mesh velocity which is used in ALE description does not enter into the stability bound. Surprisingly, the nonlinear convection term in the Navier-Stokes equations plays a crucial role to stabilize the scheme and the stability result does not apply to Stokes flow. As the nonlinear convection term is treated semi-implicitly, in each time step, we only need to solve a linear system (and only once) which involves merely (u;p;v) if the solid is linear elastic. Two numerical tests including the benchmark test of Navier-Stokes flow past a Saint Venant-Kirchhoff elastic bar are performed. In addition to the stability, we also confirm the first order temporal accuracy of our explicit interface advancing scheme.
Quasi-periodic Solutions of a Derivative Nonlinear Schr?dinger Equation
Jie Liu
Mathematics , 2014, DOI: 10.1080/00036811.2015.1032942
Abstract: This paper is concerned with a one dimensional (1D) derivative nonlinear Schr\"odinger equation with periodic boundary conditions \begin{equation*} \mi u_t+u_{xx}+\mi |u|^2u_x=0, \ \ x\in \mathbb{T}:=\mathbb{R}/2\pi\mathbb{Z}. \end{equation*} We show that above equation admits a family of real analytic quasi-periodic solutions with two Diophantine frequencies. The proof is based on a partial Birkhoff normal form and KAM method.
A New Algorithm of Mobile Node Localization Based on RSSI  [PDF]
Jie Zhan, Hongli Liu, Bowei Huang
Wireless Engineering and Technology (WET) , 2011, DOI: 10.4236/wet.2011.22016
Abstract: Position mobile node coordinate is a key component to determine the accuracy and efficiency of positioning in wireless sensor networks. Flexible location algorithm admits to adjust the accuracy and time cost of positioning based on the users references. This paper develops a location algorithm named Signal Strengthening Dynamic Value (SSDV) based on the database of RSSI to position the mobile node in terms of the value of beacon nodes RSSI. The proposed algorithm has successfully improved the accuracy of mobile nodes positioning and real-time, and simulation results show high performance in effectiveness of the algorithm.
A Velocity-Adaptive Handover Scheme for Mobile WiMAX  [PDF]
Caiyong HAO, Hongli LIU, Jie ZHAN
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.29101
Abstract: Mobile WiMAX is a wireless networking system based on the IEEE 802.16e standard. In order to support mobile, some kinds of handover schemes must be adopted, and the hard handover is defined as mandatory. Since the data transmission should be paused during the hard handover process, it causes handover delay in mobile communication. The handover delay makes severe degradation in system performance when implemented in real-time applications such as IPTV and VoIP. The existing draft standard considers only the received signal strength when deciding handover initiation. However, the velocity factor also has an important influence on handover initiation and can not be neglected. To deal with these problems, this article proposes a velocity-adaptive handover scheme. This scheme adopts dynamic handover threshold according to different velocity to skip some unnecessary handover stages, reduces handover delay and enhances the network resource utilization. The simulation result and performance analysis validate the efficiency of the proposed scheme.
Study on the Simulation Technique for Urban Electromagnetic Environment Supported by GIS  [PDF]
Yanming CHEN, Jie LIU, Jiechen WANG
Journal of Geographic Information System (JGIS) , 2009, DOI: 10.4236/jgis.2009.11004
Abstract: Electromagnetic radiation environment is one of the important environmental factors. In resent 20 years, the applications of electromagnetic technology became more and more popular. However, electromagnetic environment makes some negative impacts on the surrounding environments and human health, and Environmental Management and Research Department pay a lot attention to it. It will make a great significance if we study of the simulation technique for urban electromagnetic environment which supported by GIS. This paper presents some key technologies of the electromagnetic environment simulation, including terrain rendering, city building modeling and volume data superposition, basically realize the visualization of volume data (electromagnetic fields) based on city building model and real time mapping of virtual scene data.
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