OALib Journal期刊

ISSN: 2333-9721




2019 ( 34 )

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匹配条件: “ Zhao Zhang” ,找到相关结果约124773条。
Solution and Type Curve Analysis of Fluid Flow Model for Fractal Reservoir  [PDF]
Yulong Zhao, Liehui Zhang
World Journal of Mechanics (WJM) , 2011, DOI: 10.4236/wjm.2011.15027
Abstract: Conventional pressure-transient models have been developed under the assumption of homogeneous reservoir. However, core, log and outcrop data indicate this assumption is not realistic in most cases. But in many cases, the homogeneous models are still applied to obtain an effective permeability corresponding to fictitious homogeneous reservoirs. This approach seems reasonable if the permeability variation is sufficiently small. In this paper, fractal dimension and fractal index are introduced into the seepage flow mechanism to establish the fluid flow models in fractal reservoir under three outer-boundary conditions. Exact dimensionless solutions are obtained by using the Laplace transformation assuming the well is producing at a constant rate. Combining the Stehfest’s inversion with the Vongvuthipornchai’s method, the new type curves are obtained. The sensitivities of the curve shape to fractal dimension (θ) and fractal index (d) are analyzed; the curves don’t change too much when θ is a constant and d change. For a closed reservoir, the up-curving has little to do with θ when d is a constant; but when θ is a constant, the slope of the up-curving section almost remains the same, only the pressure at the starting point decreases with the increase of d; and when d = 2 and θ = 0, the solutions and curves become those of the conventional reservoirs, the application of this solution has also been introduced at the end of this paper.
Animal bone growth experiment of rapid-growing rats in different stress environment and its mathematical model  [PDF]
Jun Zhang, Wenzhi Zhao
Journal of Biosciences and Medicines (JBM) , 2013, DOI: 10.4236/jbm.2013.12005

The aim of this study is to explore a way that quantify the qualitative equation of bone growth and remodeling which was based on the animal Experiment of rapid-growing Rats in Different Stress Environment. These results were proved to be of good stability and identification precision with the numerical method of inversion. It suggested that the growing coefficient and the threshold in function were variables changing with time and space. The idea and method used in the research of bone growth and remodeling adaptation in this paper also provided clue and reference to establish other models for living system.

Research on the Maturity Model of Conflict Management in Engineering Project  [PDF]
Wan Zhang, Hui Zhao
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.23002

Integrated Project Management Maturity proposed a new concept. It is “Project Conflict Management Maturity”. It established a new concept of maturity level, established an evaluation index system on Project Conflict Management Maturity and used the multi-level fuzzy comprehensive evaluation method combined with the Project Management Maturity model to construct the maturity model of Project Conflict Management. Then, through numerical examples, it evaluated the score of object, got the maturity level of conflict management of the study project, verified the feasibility of the model for solving Project Conflict Management, provided some bases for solving problems of Project Conflict Management and had a certain practical significance about this problem.

Correction to the Chiral Magnetic Effect from axial-vector interaction
Zhao Zhang
Physics , 2012, DOI: 10.1103/PhysRevD.85.114028
Abstract: The recent lattice calculation at finite axial chemical potential suggests that the induced current density of the chiral magnetic effect (CME) is somehow suppressed comparing with the standard analytical formula. We show in a NJL-type model of QCD that such a suppression is a natural result when considering the influence of the attractive axial-vector interaction. We point out that the lattice result doesn't need to be quantitatively consistent with the analytical formula due to the chirality density-density correlation. We also investigate the nonperturbative effect of instanton molecules on the CME. Since an unconventional repulsive axial-vector interaction is induced, the CME will be enhanced significantly by the instanton-anti-instanton pairings. Such a prediction needs to be tested by more improved lattice simulations. We further demonstrate that the axial-vector interaction plays an important role on the $T-\mu_A$ phase diagram.
Research and Application of 3G Electrical Safety Job Site Intelligent Monitoring Device  [PDF]
Changqing Zhao, Chenxu Zhao, Heng Xu, Haijun Zhang, Minghao Sun
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B169

This paper describes the shortcomings and difficulties of power company security construction, such as site management for construction site security monitoring personnel is limited, in recent years , rural power grids and Urban Network alteration Faced with new situation. The use of advanced science and technology and communication terminal in order to better strengthen the means of power construction site safety supervision, improve the level of safety production supervision, design and development of a new electrical safety job site intelligent monitoring devices. The device consists of three parts of the remote wide angle 360 degrees of portable video surveillance equipment and 3G smart terminal equipment and portable battery. Through the application of such a device, professionals can remotely monitor the construction job site safety, diagnose, and effectively improve the security of the electricity sector management and reduce security risks and personnel on-site monitoring costs for improving the security of the entire power industry field operations with significance.

Photocatalytic Treatment of Microcystin-LR-Containing Wastewater Using Pt/WO 3 Nanoparticles under Simulated Solar Light  [PDF]
Chao Zhao, Yingnan Yang, Zhenya Zhang
Open Journal of Applied Sciences (OJAppS) , 2012, DOI: 10.4236/ojapps.2012.22011
Abstract: This study investigates the photocatalytic degradation of microcystin-LR (MC-LR) under simulated solar light using Pt modified nano-sized tungsten trioxides (Pt/WO3). Photocatalytic activity was higher during the degradation of MC-LR with Pt/WO 3 than with pure WO 3 or Ti O2 . The catalyst loading greatly affect the degradation performance. The rate of degradation is influenced by the initial pH of the reaction solution. This study also investigates the photocatalytic inactivation of cyanobacteria. The results show that the algal growth was successfully controlled by the Pt/W O 3 . This study suggests Pt/W O 3 photocatalytic oxidation with solar light is a promising treatment for water containing MC-LR.
Assessing Money Laundering Risk of Financial Institutions with AHP: Supervisory Perspective  [PDF]
Ke Jia, Xi Zhao, Ling Zhang
Journal of Financial Risk Management (JFRM) , 2013, DOI: 10.4236/jfrm.2013.21004

This paper proposed a risk assessment model with which supervisory authorities can calculate the money laundering risk (MLR) level of financial institutions and make comparisons among multiple institutions. The model is based on the Analytic Hierarchy Process (AHP) and decomposes MLR into two second-tier criteria, i.e. Inherent Risk & Control Risk. AHP pair wise comparisons made by the experts from various fields are processed through AHP software to get the weight of each factor. Using this model, MLR of each financial institution could be obtained and certain comparison among them could be carried out.

The Fracture Density and Fractal Dimension Prediction Based on Support Vector Machine  [PDF]
Lei Zhao, Liehui Zhang, Yilin Wang
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.44062

The key of effective development for the fractured reservoir is to describe the distribution of the fracture and build the fracture geological model. To acquire more optimal exploration and development of the oilfield, objective geologic model of reservoir fractures is needed for further knowledge of the spatial distribution condition of fractures. Adopting well-logging and seismic techniques can be expensive and usually yield multiple solutions, yet resolution will disturb the seismic method, making it difficult to acquire accurate and sound fracture parameters from seismic data. In this paper, the theoretical foundation for support vector machine, fractal geometry, combined the various information in geology, logging, well core, seism and field outcrop about the fracture and calculate the parameters of the fracture (fracture density and fractal dimension), and the good foundation is established for fractured reservoir description of discrete fracture network model. Based on analysis of conventional prediction methods of development indices and factor influencing the parameters of the fracture, a support vector machine method is established to predict the parameters of the fracture. The new support vector machine method is based on time series analysis to select the kernel function. Trains and tests the support vector machine network with historical data to construct the support vector regression prediction model. A case was fit into the model to test and analyse its reliability, the results suggested that the model had a high prediction performance, and could be well applied to the prediction of fracture parameters.

Energy-Efficient Cross-Layer Optimization for Wireless Sensor Networks  [PDF]
Yongqiang Fei, Peng Zhang, Yuping Zhao
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53B2090

In this paper, we propose a cross-layer design combining adaptive modulation coding (AMC) and automatic repeat request (ARQ) to minimize the bit energy consumption under both packet loss rate and retransmission delay constraints. We analyze the best constellation size of M-ary square quadrature amplitude modulation (MQAM) in different distance, and give advice on retransmission limits under different packet loss rates. The impacts of path loss fading and additive white Gaussian noise (AWGN)are taken into consideration. The computation of energy consumption includes the circuit, transmission and retransmission energies at both transmitter and receiver sides. Numerical results are obtained to verify the validity of our design. We also show that the retransmission benefit varies with the packet loss rate constraint.

Relay Selection and Power Allocation in Amplify-and-Forward Cognitive Radio Systems Based on Spectrum Sharing  [PDF]
Daqian Zhao, Zhizhong Zhang, Fang Cheng
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53B2069
Abstract: In this paper, we consider a spectrum sharing scheme that is a joint optimization of relay selection and power allocation at the secondary transmitter, which aims to achieve the maximum possible throughput for the secondary user. This paper considers the scenario where the primary user is incapable of supporting its target signal-to-noise ratio (SNR). More especially, the secondary transmitter tries to assist the primary user with achieving its target SNR by cooperative amplify-and-forward (AF) relaying with two-phase. By exhaustive search for all candidate secondary transmitters, an optimal secondary transmitter can be selected, which not only can satisfy the primary user’s target SNR, but also maximize the secondary user’s throughput. The optimal secondary transmitter acts as a relay for the primary user by allocating a part of its power to amplify-and-forward the primary signal over the primary user’s licensed spectrum bands. At the same time, as a reward, the optimal secondary transmitter uses the remaining power to transmit its own signal over the remaining licensed spectrum bands. Thus, the secondary user obtains the spectrum access opportunities. Besides, there is no interference between the primary user and the secondary user. We study the joint optimization of relay selection and power allocation such that the secondary user’s throughput is maximized on the condition that it satisfies the primary user’s target SNR. From the simulation, it is shown that the joint optimization of relay selection and power allocation provides a significant throughput gain compared with random relay selection with optimal power allocation (OPA) and random relay selection with water-filling power allocation (WPA). Moreover, the simulation results also shown that our spectrum sharing scheme obtains the win-win solution for the primary system and the secondary system.

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