DSpace collection: 第19卷第2期

Establishing the Formation Pressure Profile of Predrill Well Based on Adjacent Wells Data

title: Establishing the Formation Pressure Profile of Predrill Well Based on Adjacent Wells Data abstract: The formation pressure plays a very important role in drilling engineering. So it is of great significance to predict formation pressure before drilling. In order to solve the problem, the concept of formation matrix and wellbore matrixwere put forward. Also the method of epitaxial transplantation for the regional formation pressurewas proposed. With the concept of wellbore pressure matrix, the target wellbore pressure matrix can be builtby dealing with the adjacent wellborepressureusing the method of depth adjustment and weighted distance correction. Finally, we can obtain the formation pressure of the targetwell. Case study of Qinghai Oilfield was carried out to test the method. Through comparative analysis, the maximum relative error of the transplantation pressure and logging interpretation pressure is 4.2%. The result indicated that the accuracy and reliability of the method can meet the engineering requirement. This is conductive to designers to predict formation pressure which can provide the basis for the casing design and the selection of the drilling fluid density.

Performance Analysis of DF Relaying M2M Cooperative System

title: Performance Analysis of DF Relaying M2M Cooperative System abstract: The average symbol error probability (ASEP) of multiple-mobile-relay-based mobile-tomobile (M2M) system with decode-and-forward (DF) relaying over N-Nakagami fading channels is investigated in this paper. The moment generating function (MGF) method is used to obtain the ASEP of various modulation techniques. Then the ASEP performance under different conditions is evaluated through numerical simulations to verify the analysis. The simulation results showed that the fading coefficient, number of cascaded components, relative geometrical gain, power-allocation parameter, and number of mobile relays have an important influence on the ASEP performance.

A Routing Optimization Strategy for Wireless Sensor Networks Based on Improved Genetic Algorithm

title: A Routing Optimization Strategy for Wireless Sensor Networks Based on Improved Genetic Algorithm abstract: In order to resolve the problem of generating invalid new individual when using genetic algorithm for routing optimization in wireless sensor networks (WSNs), an improved genetic algorithm (ROS_IGA) is put forward. By considering the position and neighbors of nodes in WSNs, ROS_IGA takes reasonable crossover and mutation operation to ensure compliance with the topological of actual WSNs and the demand of communication among nodes. Furthermore, ROS_IGA takes many factors, such as the residual energy of sensor nodes, distance and energy consumption between adjacent nodes, communication delay and relay hops, into consideration to select suitable routing. So ROS_IGA increases the speed of convergence and optimizes the performance of WSNs. Finally, a simulation experiment is carried out and the experimental results show that the improved algorithm in this study can effectively finds the best routing and decreases energy consuming and also increases the network life cycle.

Estimating Rate-Distortion for Multiple Description Coding Based on Zero Padding

title: Estimating Rate-Distortion for Multiple Description Coding Based on Zero Padding abstract: In the studies related to multiple description coding (MDC), applying zero padding not only improves the spatial correlation between descriptions but also increases their sizes. However, as we pad more zeros, the spatial correlation does not improve linearly. Therefore, the distortion is not reduced as the same amount when the size increases. In this paper, we focus on how to efficiently find an acceptable trade-off between the number of padded zeros and the increase of distortion in MDC. In this paper, we propose two distortion estimations for MDC with zero padding based on spatial quincunx distribution, which are standard deviation for distortion estimation and triangular linear approximation distortion estimation (TLA-DE) to efficiently calculate the distortion for the number of padded zeros atthe horizontal direction. In order to search for the acceptable number of padded zeros, we propose two search methods, Naïve Search and Best Division Search, which are both based on the proposed rate-distortion trade-off indicator. Our experiments result show that the worst error of distortion estimation by TLA-DE is up to 18%, but the average is 5.5% with 95% confidence level. The executing time of best division search is about two times faster than that of naïve search for 11 test sequences. To sum up, we confirm that the acceptable trade-off between rate and distortion in low computational complexity can be found by using the best division search on TLA-DE.

Analysis of Heat Transfer Coefficients in Direct Contact Membrane Distillation Modules Using CFD Simulation

title: Analysis of Heat Transfer Coefficients in Direct Contact Membrane Distillation Modules Using CFD Simulation abstract: Membrane distillation (MD) isan emerging separation technology for desalination, solution concentration and waste water treatment. As a thermal driven device, heat transfer coefficients are critical to the MD performance. In this study, the transmembrane heat and mass transfers are rigorously accounted for in the computational fluid dynamics (CFD) simulation. Flat plate direct contact membrane distillation (DCMD) modules with smooth-surface and rough-surface channels as well as in co-flow and counter-flow configurations are analyzed for the desalination application. For different rough-surface channels, flow configurations and operation conditions, the simulated permeation fluxes are fairly close to the experimental results. The local distributions of heat transfer coefficients show very high values at fluid inlets. For the simulated flat plate modules, the local heat transfer coefficients fall between conventional correlations of heat exchangers with circular channels and parallel plates and the module average heat transfer coefficients are much higher than the conventional correlations. This study reveals the values and distribution characteristics of the heat transfer coefficients in DCMD modules, which is important for the design of DCMD modules.

Third-Order Sinusoidal Oscillator Using a Single CMOS Operational Transresistance Amplifier

title: Third-Order Sinusoidal Oscillator Using a Single CMOS Operational Transresistance Amplifier abstract: This paper presents the design of a compact third-order sinusoidal oscillator based on an operational transresistance amplifier (OTRA). The proposed circuit consists of a single OTRA combined with three resistors and three capacitors. A review of relevant literature revealed that this is the first study to design a third-order sinusoidal oscillator, constructed with a single OTRA and the minimal number of passive components, with independent control of the oscillation condition and frequency. This study involved a review of previous designs as well as related formulations, nonideal analyses, and sensitivity discussions regarding the proposed circuit. Because the proposed circuit features a low-impedance output, it can be applied in cascading and used without additional buffer circuits. This study conducted simulations for the proposed circuit using HSPICE, and used commercially integrated circuits (ICs) and discrete components for circuit implementation and testing to verify its feasibility. Simulation and experimental results confirmed the validity of the proposed oscillator circuit.

A Modified Method for Risk Evaluation in Failure Mode and Effects Analysis

title: A Modified Method for Risk Evaluation in Failure Mode and Effects Analysis abstract: This study proposes a modified failure mode and effects analysis (FMEA) method based on fuzzy set theory and fuzzy analytic hierarchy process (FAHP) by analyzing the limitations of the traditional FMEA. First, the fuzzy language set of severity, occurrence, and detection is set up in this method. Second, the failure mode is evaluated by a triangular fuzzy number based on the fuzzy language set. Then, the weights of severity, occurrence, and detection are determined by the FAHP. Finally, the risk priority of the failure modes is determined by the modified risk priority number (RPN). The efficiency and feasibility of the modified FMEA method are verified by using it to deal with risk evaluation of the failure modes for a compressor crankshaft.

Rainfall Landslide in Sedimentary and Sub-Metamorphic Rock an Example in Kaoping River Basin

title: Rainfall Landslide in Sedimentary and Sub-Metamorphic Rock an Example in Kaoping River Basin abstract: Many researches employed several landslide-related factors such as the slope-aspect, size, lithology etc. to study the landslide assessment. Utilizing the landslide inventory delineated by 1:5000 high resolution aerial photo, this article explored the landslide characteristics, such as the landslide area, slump direction and air current for two different rock types in Kaoping River basin during the period of 2009 Typhoon Morakot. It is found that the air current direction is the dominant factor for landslides triggered by a heavy rainfall in Kaoping River basin. The number and size of landslides in slate is larger than the sedimentary rock. This indicates the slate region in Kaoping River basin is more likely to take place landslide; however, the landslide characteristic in size distribution is similar.

Numerical Investigations of Body Tail Projectile

title: Numerical Investigations of Body Tail Projectile abstract: The unsteady compressible flow around a body tail projectile is numerically solved with a Large Eddy Simulation (LES) method, Smagorinsky-Lilly model was used as the Sub-Grid Scale (SGS). The computed results are obtained in supersonic flow regime for a viscous fluid in order to determine the aerodynamic coefficients with different angles of attack. The flow around a body tail projectile was solved as a three-dimensional flow.

Optimization Design for Screw Wash-Sand Machine Based on Fruit Fly Optimization Algorithm

title: Optimization Design for Screw Wash-Sand Machine Based on Fruit Fly Optimization Algorithm abstract: The aim of this study is to minimize the specific energy consumption of the screw wash-sand machine. Let the diameter of the screw structure, pitch, diameter of the screw axis, blade thickness, installation angle, and the speed of the screw axis be the design variables, and take the minimum specific energy consumption as the optimization objective. According to the complexity of the optimization problem in this study, the fruit fly optimization algorithm (FOA) is used to execute the optimization design of the screw wash-sand machine. The non-stationary multi-stage assignment penalty function is adopted to cope with the constrained optimization problem. To judge the stability and reliability of the optimal solution and find the sensitive factors of the optimization design, the sensitivity analyses of the objective function and constraint conditions to the design variables are carried out. By simulation, the optimized structure parameters of the screw wash-sand machine and the data of the objective sensitivity and constraint sensitivity are obtained. The simulation results show that the specific energy consumption decreases by 4.59%; the diameters of the screw structure and screw axis are sensitive factors of the optimization design.

Free Vibrations of Homogenous Isotropic Viscothermoelastic Spherical Curved Plates

title: Free Vibrations of Homogenous Isotropic Viscothermoelastic Spherical Curved Plates abstract: In this paper free vibration analysis of viscothermoelastic spherical curved plate has been presented to study the spheroidal and toroidal vibrations. The basic governing partial differential equations have been reduced to ordinary differential equations for time harmonic vibrations. Coupled systems of equations represent spheroidal vibrations, while uncoupled equation corresponds to toroidal vibrations. These uncoupled vibrations remain independent of temperature variations. Matrix Fröbenious method of extended power series has been applied to derive the formal solution of the coupled system of ordinary differential equations. The analytical results have been computed numerically for polymethyle methacrylate material. The fundamental iteration technique have been used to compute eigen values and corresponding eigen functions to represent field quantities with the help of MATLAB software. The numerical results in respect of lowest frequency, dissipation factor, stresses, displacements and temperature change have been presented graphically.

Investigation on Non-Gaussian Peak Factors for Wind Pressures on Domed Roof Structures

title: Investigation on Non-Gaussian Peak Factors for Wind Pressures on Domed Roof Structures abstract: Roof curvature and Reynolds number effect significantly define the characteristics of wind pressures on domed roof structures. Once the flow separates from the roof surface, apparent changes in aerodynamic coefficients or non-Gaussian wind-induced pressure spectra are expected. This paper investigated the non-Gaussian peak factors of wind pressure coefficients on domed roofs under a simulated suburban boundary layer flow. By estimating the higher statistic moments, skewness and kurtosis coefficients, and adopting the moment-based Hermite polynomial translation techniques, including the softening and hardening processes, comparisons were made based on the empirical and simulated results. The fairly good estimation results by translation process were demonstrated and the influence on the estimation of wind pressure extremes was discussed in a practical viewpoint.

Optimization of Biodiesel Production Using Multi-Objective Genetic Algorithm

title: Optimization of Biodiesel Production Using Multi-Objective Genetic Algorithm abstract: In this modern technological age, one of the challenges facing the transportation industry, is finding a less polluting substitute for diesel. Meanwhile, any kind of fuel due to the cetane number specified in a diesel cycle cannot be utilized. One of the alternatives for this is biodiesel which is indirectly obtained from animal fat in the presence of alcohol. Cost of biodiesel is more than that of conventional fuels; therefore, optimization of industrial production of biodiesel is with major importance. There are several methods to obtain the optimum temperature for biodiesel production process. In this paper, genetic algorithm, as one of the strongest evolutionary algorithms, has been applied to biodiesel production to obtain the best reaction parameters. Moreover, in order to have a robust optimization, multi objective genetic algorithm is employed. The achieved temperature point for maximizing biodiesel production was a wide range of temperature which can be illustrated as Pareto front to help making the final decision. This study was aimed to maximize the amount of Ester and Alcohol in this production and minimize the other products. This result can define a new strategy for industrial biodiesel production planning.

Finslerian Hypersurfaces and Generalized Change of Finsler Metric

title: Finslerian Hypersurfaces and Generalized Change of Finsler Metric abstract: In the present paper, using the field of linear frame [13], we shall considered Finslerian hypersurfaces given by generalized change of Finsler metric. The generalized change of Finsler metric is given by L = f (L, 1), 2),…, m) ), where f is any positively homogeneous function of degree one in L and 1), 2),…, m). Our purpose is to give some relations between the original Finslerian hypersurface and the other which is Finslerian given by generalized change. We have shown that generalized change makes three types of hypersurfaces invariant under certain conditions. Also, we have obtained the conditions under which this change will be a hyperplane of first, second and third kind.