Net Gains from Conjunctive Use of Surface and Ground Water

Pakistan is fortunate enough because its soils, topography and climate are generally suitable for farming but its agriculture sector faces the problem of scarcity of the irrigation water. This paucity of irrigation supplies has forced the farmers to use the ground water to augment their surface supplies. The quality of ground water in Pakistan varies from fit for irrigation to moderately saline to sodic. Thus the tubewell owners in the marginal quality ground water areas are bound to use the tubewell water in conjunction with the surface water on their farms. Currently the farmers are using about 65.75 BCM of ground water in Pakistan [Halcrow (2002)]. The international literature is filled with the studies on conjunctive water management and its impact on crop productivity and related issues [Gangwar and Toorn (1987); Bredehoeft and Young (1983); Gorelick (1988); Lingen (1988); O’Mara (1988); Shah (1988); Brewer and Sharma (2000); Datta and Dayal (2000); Raju and Brewer (2000); Sakhtivadivel and Chawala (2002) and Chaudhary and Shah (2003)]. In Pakistan, the review of literature shows that all of the previous studies conducted in the arena of water management reported the management problems leading to the inefficiencies in irrigation application and reduction in crop productivity, [Kijne and Velde (1991); Mustafa (1991) and Siddiq (1994)]. Few of the studies took into consideration the impact of waterlogging and salinity on productivity at farm level [Meyer, et al. (1996); Prathaper, et al. (1997) and O’Connell and Khan (1999)]. None of these studies have taken into consideration the trade-offs between gross farm income, ground water and salinity at irrigation subdivision level. To answer the issues of spatial differences in the trade offs between gross farm income, ground water and salinity at irrigation Subdivision level, this paper presents the results of the optimisation modeling at the Subdivisional level

Efficiency Improvement of Fault-Tolerant Three-Level Power Converters

Fault-tolerant power converters play a critical role in the transportation electrification. However, fault-tolerant operation, high efficiency, and low cost usually result in design criteria that have conflicting constraints and goals. The majority of the fault-tolerant power converter topologies presented in the literature confirm these conflicts. In this paper, three types of fault-tolerant neutral-point clamped (NPC) converters are investigated. Various modulation strategies are explored to reduce the losses of the redundant phase leg. The simulation and experimental results show that the Switching Frequency Optimal Phase opposition Disposition modulation strategy is the most effective approach in minimizing the losses in the redundant phase leg

Production Trends of Shale Gas Wells

To obtain better well performance and improved production from shale gas reservoirs, it is important to understand the behavior of shale gas wells and to identify different flow regions in them over a period of time. It is also important to understand best fracture and stimulation practice to increase productivity of wells. These objectives require that accurate production analysis be performed. For accurate production analysis, it is important to analyze the production behavior of wells, and field production data should be interpreted in such a way that it will identify well parameters. This can be done by performing a detailed analysis on a number of wells over whole reservoirs. This study is an approach that will lead to identifying different flow regions in shale gas wells that include linear and bilinear flow. Important field parameters can be calculated from those observations to help improve future performance. The detailed plots of several wells in this study show some good numbers for linear and bilinear flow, and some unique observations were made. The purpose of this work is to also manage the large amount of data in such a way that they can be used with ease for future studies. A program was developed to automate the analysis and generation of different plots. The program can also be used to perform the simple calculations to calculate different parameters. The goal was to develop a friendly user interface that would facilitate reservoir analysis. Examples were shown for each flow period, i.e. linear and bilinear flow. Different plots were generated (e.g; Bob Plot (square root of time plot) and Fourth Root of Time Plot, that will help in measuring slopes and thus reservoir parameters such as fracture permeability and drainage area. Different unique cases were also observed that show a different behavior of well in one type of plot from another

Net Gains from Conjunctive Use of Surface and Ground Water

Pakistan is fortunate enough because its soils, topography and climate are generally suitable for farming but its agriculture sector faces the problem of scarcity of the irrigation water. This paucity of irrigation supplies has forced the farmers to use the ground water to augment their surface supplies. The quality of ground water in Pakistan varies from fit for irrigation to moderately saline to sodic. Thus the tubewell owners in the marginal quality ground water areas are bound to use the tubewell water in conjunction with the surface water on their farms. Currently the farmers are using about 65.75 BCM of ground water in Pakistan [Halcrow (2002)]. The international literature is filled with the studies on conjunctive water management and its impact on crop productivity and related issues [Gangwar and Toorn (1987); Bredehoeft and Young (1983); Gorelick (1988); Lingen (1988); O’Mara (1988); Shah (1988); Brewer and Sharma (2000); Datta and Dayal (2000); Raju and Brewer (2000); Sakhtivadivel and Chawala (2002) and Chaudhary and Shah (2003)]. In Pakistan, the review of literature shows that all of the previous studies conducted in the arena of water management reported the management problems leading to the inefficiencies in irrigation application and reduction in crop productivity, [Kijne and Velde (1991); Mustafa (1991) and Siddiq (1994)]. Few of the studies took into consideration the impact of waterlogging and salinity on productivity at farm level [Meyer, et al. (1996); Prathaper, et al. (1997) and O’Connell and Khan (1999)]. None of these studies have taken into consideration the trade-offs between gross farm income, ground water and salinity at irrigation subdivision level

Irreversibilities in a triple diffusive flow in various porous cavities

Entropy generation minimization approach is a very good method allowing to analyze the engineering systems to exclude technical failure. The present study deals with computational analysis of triple diffusive flow, energy transference and entropy production in different porous cavities from square to triangular through trapezoidal shape. The formulated boundary-value problem has been worked out using the finite element technique and non-primitive variables. The developed computational code has been verified using numerical results of other researchers. Analysis of entropy production due to energy and mass transport, motion friction, and porous material has been performed for different chamber's shapes. Entropy generation analysis in chambers of various geometries under the triple-diffusive flow is a novelty of the present research, where different entropy production mechanisms have been scrutinized for one complex problem. It has been ascertained that average total entropy generation strength raises with buoyancy ratios, Lewis and Rayleigh numbers, but it has the minimum value for the square chamber in comparison with triangular and trapezoidal shapes. Moreover, obtained results characterize a neglecting influence of motion friction on the total entropy generation

Boundary Layer Flow Past a Wedge Moving in a Nanofluid

The problem of steady boundary layer flow past a stretching wedge with the velocity in a nanofluid and with a parallel free stream velocity is numerically studied. It is assumed that at the stretching surface the temperature and the nanoparticle fraction take the constant values and , respectively. The ambient values (inviscid fluid) of and are denoted by and , respectively. The boundary layer governing partial differential equations of mass, momentum, thermal energy, and nanoparticles recently proposed by Kuznetsov and Nield (2006, 2009), are reduced to ordinary differential equations along with the corresponding boundary conditions. These equations are solved numerically using an implicit finite-difference method for some values of the governing parameters, such as , , , , , and , which are the measure of the pressure gradient, moving parameter, Prandtl number, Lewis number, the Brownian motion parameter, and the thermophoresis parameter, respectively

Electrothermal Design of a GaN-Based Axially Stator Iron-Mounted Fully Integrated Modular Motor Drive

The concept of More Electric Aircraft (MEA) has gained a lot of attention from researchers recently. For such an application, two of the pivotal requirements are having a power dense and energy efficient propulsion system. To that end, in the design procedure of the electric motor and its drive system, high power density and efficiency over the entire operating range is the ultimate goal. Thus, the integration of the electric motor and drive system into a single unit has been introduced as an effective method to meet the design objectives. Therefore, this paper presents the design procedure of a module of an Integrated Modular Motor Drive (IMMD). Electrothermal design of the GaN single phase full bridge inverter module has been conducted and the results are discussed. The analysis includes the thermal investigation of the WBG semiconductors by sweeping the number of parallel devices in each switch position at different switching frequencies. Furthermore, a single drive PCB module is designed and evaluated in ANSYS Q3D for parasitic extraction. Finally, double pulse test (DPT) is performed to verify the optimal design of PCB busbar

Unsteady slip flow of amicropolarnanofluid over an impulsively stretched vertical surface

The unsteady mixed convective flow of micropolarnanofluid over an impulsively stretched vertical surface has been examined. A model has been developed to analyze the behavior of nanofluids in presentmicropolar fluids studied numerically for both cases of assisting and opposing flow taking into account the thermal convective boundary condition. A model has been developed to analyze the behavior of nanofluids containing metallic nanoparticles as copper (Cu)and nonmetallic nanoparticles as alumina (A  in water-micropolarnanofluidhave been considered. The governing partial differential equations have been transformed to non-similar differential equations then have been solved numerically by using theRunge-Kutta-Fehlberg method of seventh order (RKF7). The results have been compared with the published results and are found in excellent agreement

Application of Adomian Decomposition Method for Sumudu Transform

In this paper, Adomian decomposition method (ADM) is employed to compute Sumudu transform of some typical functions. In this method, the solution is found in the form of a convergent power series with  easily  computed components. To  show  the  efficiency  of  the  method, numerical examples are presented and a MAPLE code is provided that computes Sumudu transform of typical functions quickly. It is demonstrated that like HPM, this method is also quite easy and fast to compute Sumudu transforms

Application of Genetic Algorithms in Nonlinear Heat Conduction Problems

Genetic algorithms are employed to optimize dimensionless temperature in nonlinear heat conduction problems. Three common geometries are selected for the analysis and the concept of minimum entropy generation is used to determine the optimum temperatures under the same constraints. The thermal conductivity is assumed to vary linearly with temperature while internal heat generation is assumed to be uniform. The dimensionless governing equations are obtained for each selected geometry and the dimensionless temperature distributions are obtained using MATLAB. It is observed that GA gives the minimum dimensionless temperature in each selected geometry