The dispersion mechanism of TiB2 ceramic phase in molten aluminium and its alloys

Titanium diboride (TiB₂) ceramic particulates are dispersed in molten aluminium and its alloys for grain refining and for making cast metal–matrix composites. For producing cast MMC, the dispersion of the ceramic phase via in-situ aluminothermic reduction of K₂TiF₆ and KBF₄ flux mixture with molten aluminium and, via the addition of exogenously formed TiB₂ with the fluoride flux has been studied at 900°C. In this article, the aspects of interfacial energy that govern the dispersion and agglomeration of TiB₂ particulates are examined. The Gibbs-adsorption interface equation is particularly employed to define and to quantify the change in the surface energy as a function of the alloying element concentration and, consequently the effect of interfacial energy on the nucleation rate of TiB₂ formed via metallothermic reduction reaction and the size of the ceramic phase is also explained.     

Analysis of grid connected induction generators driven byhydro/wind turbines under realistic system constraints

Results of an investigation dealing with the behaviour of grid-connected induction generators (GCIGs) driven by typical prime movers such as mini-hydro/wind turbines are presented. Certain practical operational problems of such systems are identified. Analytical techniques are developed to study the behavior of such systems. The system consists of the induction generator (IG) feeding a 11 kV grid through a step-up transformer and a transmission line. Terminal capacitors to compensate for the lagging VAr are included in the study. Computer simulation was carried out to predict the system performance at the given input power from the turbine. Effects of variations in grid voltage, frequency, input power, and terminal capacitance on the machine and system performance are studied. An analysis of self-excitation conditions on disconnection of supply was carried out. The behavior of a 220 kW hydel system and 55/11 kW and 22 kW wind driven system corresponding to actual field conditions is discussed     

Potential of fly ash to suppress the susceptible behavior of lime-treated gypseous soil

The use of lime and fly ash to improve the properties of certain types of soil is well established. However, the potential of fly ash to control the adverse effects of lime-treated gypseous/sulphatic soil has not been well investigated. In the present work, an attempt is made to quantify the fly ash content used to suppress the susceptible behavior of lime-treated gypseous soil. Series of one-dimensional swell and compressibility analyses are performed on various combinations of expansive soil with a predominance of montmorillonite mineral containing lime, gypsum (0–6%), and fly ash (0–30%). It is observed that the volume change behavior of the lime-treated gypseous soil is not controlled completely by addition of fly ash. However, the maximum improvement in the volume change behavior of the lime-treated gypseous soil is observed with a 20% fly ash content, and hence, can be taken as the Optimum Fly ash Content (OFC). Micro-analyses revealed that the relative dominance of the change in gradation and the formation of cementitious compounds of different compositions and ettringite crystals are the key factors in controlling the volume change behavior of lime-treated gypseous soil with fly ash. However, several factors, such as the types of minerals present in the soil, the types of fly ash and lime, and other physico-chemical environmental conditions (temperature, method of curing, and so on), are seen in the present study to affect the value of the obtained OFC.     

Experimental investigation into tool aging effect in ball end magnetorheological finishing

The International Journal of Advanced Manufacturing Technology - Magnetorheological (MR) finishing is a smart finishing processes applied to a variety of applications. In the present work, an...     

A slow wave structure and its application in bandpass filter design

This paper presents a new slow wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of different kind of coupling in this structure is demonstrated. Two and four resonator band pass filters at center frequency 2.15 and 2.30 GHz with different bandwidth are designed. The simulated results are verified with the help of two different software packages (IE3D and Sonnet Lite).     

Laboratory investigation of bearing capacity behaviour of strip footing on reinforced flyash slope

The paper presents the results of laboratory model tests on bearing capacity behaviour of a strip footing resting on the top of a geogrid reinforced flyash slope. A series of model footing tests covering a wide range of boundary conditions, including unreinforced cases were conducted by varying parameters such as location and depth of embedment of single geogrid layer, number of geogrid layers, location of footing relative to the slope crest, slope angles and width of footing. The results of the investigation indicate that both the pressure–settlement behaviour and the ultimate bearing capacity of footing resting on the top of a flyash slope can be enhanced by the presence of reinforcing layers. However the efficiency of flyash geogrid system increases with the increasing number of geogrid layers and edge distance of footing from the slope. Based on experimental results critical values of geogrid parameters for maximum reinforcing effects are established. Experimental results obtained from a series of model tests have been presented and discussed in the paper.     

使用系统总线性能计数器来测量和改善嵌入式系统的性能

了解系统总线的活动情况可帮助开发工程师显著改善嵌入式应用的性能。过去,由于嵌入式处理器缺乏复杂的软硬件结合特性,因此监测系统总线的活动情况是一项挑战性难题。在系统级了解应用程序的行为对于有效利用系统资源非常关键,这些资源包括外部存储器、DMA控制器、仲裁、系统总线互连等。     

Artificial Neural Network Modeling for Groundwater Level Forecasting in a River Island of Eastern India

Forecasting of groundwater levels is very useful for planning integrated management of groundwater and surface water resources in a basin. In the present study, artificial neural network models have been developed for groundwater level forecasting in a river island of tropical humid region, eastern India. ANN modeling was carried out to predict groundwater levels 1 week ahead at 18 sites over the study area. The inputs to the ANN models consisted of weekly rainfall, pan evaporation, river stage, water level in the drain, pumping rate and groundwater level in the previous week, which led to 40 input nodes and 18 output nodes. Three different ANN training algorithms, viz., gradient descent with momentum and adaptive learning rate backpropagation (GDX) algorithm, Levenberg–Marquardt (LM) algorithm and Bayesian regularization (BR) algorithm were employed and their performance was evaluated. As the neural network became very large with 40 input nodes and 18 output nodes, the LM and BR algorithms took too much time to complete a single iteration. Consequently, the study area was divided into three clusters and the performance evaluation of the three ANN training algorithms was done separately for all the clusters. The performance of all the three ANN training algorithms in predicting groundwater levels over the study area was found to be almost equally good. However, the performance of the BR algorithm was found slightly superior to that of the GDX and LM algorithms. The ANN model trained with BR algorithm was further used for predicting groundwater levels 2, 3 and 4 weeks ahead in the tubewells of one cluster using the same inputs. It was found that though the accuracy of predicted groundwater levels generally decreases with an increase in the lead time, the predicted groundwater levels are reasonable for the larger lead times as well.     

Computational analysis and heat transfer on MHD transient-free convection flow in a vertical microporous channel in the existence of Hall and ion slip current

This investigation presents an analysis of the transient magnetohydrodynamic flow of Newtonian viscous fluid in a vertical microporous channel with the inclusion of ion slip-Hall current as well as an induced magnetic field (IMF) effects. Owing to the nature of the flow equations which are difficult to obtain an analytical result, a numerical scheme (PDEPE) based on finite difference approximation is adopted in solving the governing dimensional partial differential equation. The active influence of different flow parameters on velocity and IMF along the main flow and induced flow directions are visualized. Furthermore, variations of shear stress and induced current density are also presented in tabular form for active nondimensional flow quantities and later on analyzed. To establish the validity of the results obtained in this computation, values for velocity and IMF in this analysis were correlated with the steady-state existing benchmark when the values of nondimensional time are considered large. Significant results from the analysis show that at the transient time and in the simultaneous occurrence of suction/injection at the microchannel walls, higher values of ion slip current have no considerable influence on flow formation along the primary flow direction, whereas an oscillatory phenomenon is observed along the secondary flow direction. It is also significant to note that at a transient time, magnetic induction could be improved or controlled by choosing favorable values of the suction/injection parameter.     

Numerical study of defect in end plug weld joint of FBTR fuel pin

The fuel pins of fast reactor encounter high pressure, high temperature, high neutron fluence and sodium environment in their life time. This demands for high level of end plug weld integrity and hence, the acceptance criteria for these welds are very stringent. The defects usually encountered in the weld joints are micro-cracks, porosity, lack of fusion, root-pocket, etc. Amongst these weld defects, root-pocket at the weld joint is the most prominent defect observed in FBTR fuel fabrication campaign. The present paper deals with the FEM analysis of the weld zone having different sizes of root-pockets for the pressure developed inside the pin due to fission gas release and creep damage due to higher operating temperature.