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      Volume 41, Issue 9

      September 2016,   pages  933-1109

    • Thermal degradation analysis of pongamia pinnata oil as alternative liquid dielectric for distribution transformer


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      In this paper the feasibility of non-edible pongamia pinnata oil (PPO) as an alternative liquid dielectric which can be used in distribution transformers is examined. Hence, electrical, physical and chemical properties have been measured for thermally aged (with and without catalytic added) pongamia pinnata oil (PPO) and mineral oil (MO), sampled at 110°C for 180 days (according to IEC and IS standard). The experimentresults show that, electrical properties of pongamia pinnata oil with catalytic (PPOWC) are better than those of mineral oil with catalytic (MOWC). Whereas, the viscosity and density of PPOWC sample is much higher at all sampling intervals, so that care must be taken for cooling tube design of transformer. Furthermore, for all aging period the total acid content in MOWC oil samples is very low compared to PPOWC. However, these are higher molecular weight acid which is beneficial than lower molecular weight acid generated by MOWC oil samples.

    • Block truncation coding with color clumps:A novel feature extraction technique for content based image classification


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      The paper has explored principle of block truncation coding (BTC) as a means to perform feature extraction for content based image classification. A variation of block truncation coding, named BTC with color clumps has been implemented in this work to generate feature vectors. Classification performance with the proposed technique of feature extraction has been compared to existing techniques. Two widely used publicdataset named Wang dataset and Caltech dataset have been used for analyses and comparisons of classification performances based on four different metrics. The study has established BTC with color clumps as an effective alternative for feature extraction compared to existing methods. The experiments were carried out in RGB colorspace. Two different categories of classifiers viz. K Nearest Neighbor (KNN) Classifier and RIDOR Classifier were used to measure the classification performances. A paired t test was conducted to establish the statistical significance of the findings. Evaluation of classifier algorithms were done in receiver operating characteristic (ROC) space.

    • Automated test data generation for branch testing using incremental genetic algorithm


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      Cost of software testing can be reduced by automated test data generation to find a minimal set of data that has maximum coverage. Search-based software testing (SBST) is one of the techniques recently used for automated testing task. SBST makes use of control flow graph (CFG) and meta-heuristic search algorithms to accomplish the process. This paper focuses on test data generation for branch coverage. A major drawback in using meta-heuristic techniques is that the CFG paths have to be traversed from the starting node to end node for each automated test data. This kind of traversal could be improved by branch ordering, together with elitism. But still the population size and the number of iterations are maintained as the same to keep all the branches alive. In this paper, we present an incremental genetic algorithm (IGA) for branch coverage testing. Initially, a classical genetic algorithm (GA) is used to construct the population with the best parents for each branch node, and the IGA is started with these parents as the initial population. Hence, it is not necessary to maintain a huge population size and large number of iterations to cover all the branches. The performance is analyzed with five benchmark programs studied from the literature. The experimental results indicate that the proposed IGA search technique outperforms the other meta-heuristic search techniques in terms of memory usage and scalability.

    • Optimization of Weibull deteriorating items inventory model under the effect of price and time dependent demand with partial backlogging


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      In this study, we have discussed the development of an inventory model when the deterioration rate of the item follows Weibull two parameter distributions under the effect of selling price and time dependent demand, since, not only the selling price, but also the time is a crucial factor to enhance the demand in the market as well as affecting the overall finance. In the present model, shortages are approved and also partially backlogged. Optimum inventory level, the optimal length of a cycle and the expressions for profit function under various cost considerations are obtained using differential equations. These are illustrated graphically with the help of numerical examples. The sensitivity analysis of the standards of the parameters has been performed tostudy the effect on inventory optimizations.

    • Rough set based decision rule generation to find behavioural patterns of customers


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      Rough sets help in finding significant attributes of large data sets and generating decision rules for classifying new instances. Though multiple regression analysis, discriminant analysis, log-it analysis and several other techniques can be used for predicting results, they consider insignificant information also for processing which may lead to false positives and false negatives. In this study, we proposed rough set based decision rule generation framework to find reduct and to generate decision rules for predicting the Decision class. We conducted experiments over data of Portuguese Banking institution. From the proposed method, the dimensionality of data is reduced and decision rules are generated which predicts deposit nature of customers by 90%accuracy.

    • Genetic algorithms in supply chain management: A critical analysis of the literature


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      Genetic algorithms (GAs) are perhaps the oldest and most frequently used search techniques for dealing with complex and intricate real-life problems that are otherwise difficult to solve by the traditional methods. The present article provides an extensive literature review of the application of GA on supply chain management (SCM). SCM consists of several intricate processes and each process is equally important formaintaining a successful supply chain. In this paper, eight processes (where each process has a set of subprocesses) as given by Council of SCM Professionals (CSCMF) are considered. The idea is to review the application of GA on these aspects and to provide the readers a detailed study in this area. The authors have considered more than 220 papers covering a span of nearly two decades for this study. The analysis is shown in detail with the help of graphs and tables. It is expected that such an extensive study will encourage and motivate the fellow researchers working in related area; to identify the gaps and to come up with innovative ideas.

    • Turbulence characteristics of open channel flow over non-equilibrium 3-D mobile dunes


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      This paper reports velocity measurements over mobile dunes using an acoustic Doppler velocimetry (ADV). Experiments were conducted with two different flow conditions resulting in the formation of two different size mobile dunes. Dunes height, wavelength and velocity of dunes found to be increasing with increase in average flow velocity for a constant flow depth. The quasi-stationary bed condition was assumed while measuring the velocity distribution along the depth. The effect of the non-equilibrium mobile dunes on the flow characteristics and turbulence is examined by computing turbulent intensities, turbulent kinetic energy and Reynolds shear stresses using time averaged and time–space averaged velocity measurements. The magnitudes of transverse velocities are approximately 1/10 of streamwise velocities and vertical velocities are approximately half of the transverse velocities. The considerable magnitudes of transverse velocities over mobile bedforms necessitate measurement of 3-D velocity components to analyze the flow field. Computed turbulence intensities are found to be maximum in the region consisting of the trough and the reattachment point of the dunes. It is observed that streamwise turbulence intensities near the bed are twice the transverse turbulence intensities, and transverse turbulence intensities are twice the vertical turbulence intensities. Reynolds stresses (transverse fluxes of streamwise and vertical momentum) are observed to be high on mobile bedforms which shows mobile dunes reinforce the secondary currents. Peak values of turbulent kinetic energy (TKE) and Reynolds stresses are also found in the region consisting of the trough and the reattachment point. It is visually observed in the present experiments that maximum erosion takes place at the reattachment point and eroded sediment is carried as totalload and dropped on the lee slope of the subsequent downstream dune. This phenomenon is caused by flow expansion in the separation zone, and which is also the main reason for mobility of dunes and associated bedload transport. Most importantly, it is found that turbulence anisotropy increases with increase in size of mobile bedforms and anisotropy is extended up to the free surface in the flows over mobile bedforms, which proves the entire depth of flow is being disturbed by the mobile dunes.

    • Flow and scour around vertical submerged structures


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      The safety of the foundations of submerged hydraulic structures due to excessive local scour is threatened by the erosive action of the waves and currents passing around these structures. Fish and aquatic habitat is seriously affected due to the modification of the flow field caused by these submerged structures. Hence, the problems of flow characteristics and erosion around submerged structures were investigated by various researchers. A comprehensive discussion of the investigations on flow characteristics and local scour due to steady currents and waves around vertical submerged structures are presented, which comprises scour process, dimensional analysis, parameters influencing scour, temporal evolution of scour, flow field, flow visualization techniques, variation of bed shear stress, scour depth determination formulas and scour countermeasures.Although past investigations establish the effect of various parameters on scour around vertical submerged structures for live and clear water condition, yet further studies are required to analyze the scour around group of submerged structures for various bed sediments, understand the flow physics around the group and upscale the model results for the prototype.

    • Effect of vortex formation on sediment transport at dual pipe intakes


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      Vortex formation and subsequent sediment transport into the intake due to sea water withdrawal is one of the problems in coastal engineering. The effect of vortex formation on rate of sediment transport at coastal dual pipe intakes was investigated using a scaled physical model. Experiments were performed on dual pipe intakes at three common intake withdrawal directions (vertical, horizontal and with angle of 45°). In eachexperiment, the class of vortex with respect to its strength was determined. Particle tracking velocimetry (PTV) was employed to measure tangential velocity of vortices. Results indicated that the rate of sediment transport was considerably affected by the strength of formed vortices. The rate of transported sediment was increased by increasing the strength of formed vortex. Moreover, amount of sediment transport was affected by angle of pipe intakes. It could be concluded that the minimum and maximum rates of sediment transport occur for inclined and horizontal intakes, respectively.

    • Dynamic cellular manufacturing system design considering alternative routing and part operation tradeoff using simulated annealing based genetic algorithm


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      In this paper, an integrated mathematical model of multi-period cell formation and part operation tradeoff in a dynamic cellular manufacturing system is proposed in consideration with multiple part process route. This paper puts emphasize on the production flexibility (production/subcontracting part operation) to satisfy the product demand requirement in different period segments of planning horizon considering production capacity shortage and/or sudden machine breakdown. The proposed model simultaneously generates machine cells and part families and selects the optimum process route instead of the user specifying predetermined routes. Conventional optimization method for the optimal cell formation problem requires substantial amount of time and memory space. Hence a simulated annealing based genetic algorithm is proposed to explore the solution regions efficiently and to expedite the solution search space. To evaluate the computability of the proposed algorithm, different problem scenarios are adopted from literature. The results approve the effectiveness of theproposed approach in designing the manufacturing cell and minimization of the overall cost, considering various manufacturing aspects such as production volume, multiple process route, production capacity, machine duplication, system reconfiguration, material handling and subcontracting part operation.

    • Structural damage detection using ARMAX time series models and cepstral distances


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      A novel damage detection algorithm for structural health monitoring using time series model is presented. The proposed algorithm uses output-only acceleration time series obtained from sensors on the structure which are fitted using Auto-regressive moving-average with exogenous inputs (ARMAX) model. The algorithm uses Cepstral distances between the ARMAX models of decorrelated data obtained from healthy and any other current condition of the structure as the damage indicator. A numerical model of a simply supported beam with variations due to temperature and operating conditions along with measurement noise is used to demonstrate the effectiveness of the proposed damage diagnostic technique using the ARMAX time series models and their Cepstral distances with novelty indices. The effectiveness of the proposed method is validatedusing the benchmark data of the 8-DOF system made available to public by the Engineering Institute of LANL and the simulated vibration data obtained from the FEM model of IASC-ASCE 12-DOF steel frame. The results of the studies indicate that the proposed algorithm is robust in identifying the damage from the acceleration datacontaminated with noise under varied environmental and operational conditions.

    • Solution to the Riemann problem for a five-equation model of multiphase flows in non-conservative form


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      In this paper, we consider the Riemann problem for a five-equation, two-pressure (5E2P) model proposed by Ransom and Hicks for an isentropic compressible gas–liquid two-phase flows. The model is given by a strictly hyperbolic, non-conservative system of five partial differential equations (PDEs). We investigate the structure of the Riemann problem and construct an approximate solution for it. We solve the Riemann problemfor this model approximately assuming that all waves corresponding to the genuinely nonlinear characteristic fields are rarefaction and discuss their properties. To verify the solver, a series of test problems selected from the literature are presented.

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