Application of the electrodialytic pilot plant for fluoride removal

Removal of fluorine from water was investigated by electrodialysis (ED) method. In order to check the efficacy of ED unit, parameters like applied potential, the pH; initial fluoride concentrations and flow rates were varied. Significant results were obtained with concentrations of less than 10 ppm. Results were satisfactory in meeting the maximum contaminate level (MCL) of 0.01 ppm for fluoride. Effect of working parameters on energy consumption was investigated using ion-exchange membranes. Results of this study are useful for designing and operating different capacities of ED plants for recovering different ions. The ED plant was found to be satisfactory to produce a good quality drinking water from the simulated mixture by removing the unwanted ions.     

An improved procedure for detection of heart arrhythmias with novel pre‐processing techniques

The objective of this study is to develop an algorithm to detect and classify six types of electrocardiogram (ECG) signal beats including normal beats (N), atrial pre‐mature beats (A), right bundle branch block beats (R), left bundle branch block beats (L), paced beats (P), and pre‐mature ventricular contraction beats (PVC or V) using a neural network classifier. In order to prepare an appropriate input vector for the neural classifier several pre‐processing stages have been applied. Initially, a signal filtering method is used to remove the ECG signal baseline wandering. Continuous wavelet transform is then applied in order to extract features of the ECG signal. Next, principal component analysis is used to reduce the size of the data. A well‐known neural network architecture called the multi‐layered perceptron neural network is then utilized as the final classifier to classify each ECG beat as one of six groups of signals under study. Finally, the MIT‐BIH database is used to evaluate the proposed algorithm, resulting in 99.5% sensitivity, 99.66% positive predictive accuracy and 99.17% total accuracy.     

Parametric optimization of CNC turning process for hybrid metal matrix composite

Machining of hybrid metal matrix composite is difficult as the particulates are abrasive in nature and they behave like a cutting edge during machining resulting in quick tool wear and induces vibration. An attempt was made in this experimental study to evaluate the machining characteristics of hybrid metal matrix composite, and a mathematical model was developed to predict the responses, namely surface finish, intensity of vibration and work-tool interface temperature for known cutting condition while machining was performed in computer numerical control lathe. Design of experiments approach was used to conduct the trials; response surface methodology was employed to formulate a mathematical model. The experimental study inferred that the vibration in V _x, V _y, and V _z were 41.59, 45.17, and 26.45 m/s², respectively, and surface finish R _a, R _q, and R _z were 1.76, 3.01, and 11.94 μm, respectively, with work-tool interface temperature ‘T’ of 51.74 °C for optimal machining parameters, say, cutting speed at 175 m/min, depth of cut at 0.25 mm and feed rate at 0.1 mm/rev during machining. Experimental results were in close conformity with response surface method overlay plot for responses.     

Using risk analysis and Taguchi’s method to find optimal conditions of design parameters: a case study

Variation in product performance can be seen as a design failure. The fundamental principle of robust design proposed by Taguchi is to improve the quality of a product by minimizing the effect of causes of variation, without totally eliminating the causes. A method of robust design is briefly explained and its application is demonstrated with the help of a case study from Roots Industries Ltd., Coimbatore. This paper describes how the inherent modeling of product and process requirements in key characteristics (KCs) can be used to express and capture the product design intent. KCs are those features which significantly affect product function and performance, or occur when there is variation. A prototype software program (VRM Tool) was developed to house all the critical design data for process optimization and its eventual reuse. We establish a systematic process of identifying, assessing and mitigating risk in the early stage of design for a Windtone class of automobile electric horn, using robust design concept. The results suggest that the proposed robust design method is an efficient, disciplined approach that can assist a product delivery team in designing for a better functional performance and improved reliability of the entire system .     

A new energy optimal control scheme for a separately excited DC motor based incremental motion drive

This paper considers minimization of resistive and frictional power dissipation in a separately excited DC motor based incremental motion drive （IMD）. The drive is required to displace a given, fixed load through a definite angle in specified time, with minimum energy dissipation in the motor windings and minimum frictional losses. Accordingly, an energy optimal （EO） control strategy is proposed in which the motor is first accelerated to track a specific speed profile for a pre-determined optimal time period. Thereafter, both armature and field power supplies are disconnected, and the motor decelerates and comes to a halt at the desired displacement point in the desired total displacement time. The optimal time period for the initial acceleration phase is computed so that the motor stores just enough energy to decelerate to the final position at the specified displacement time. The parameters, such as the moment of inertia and coefficient of friction, which depend on the load and other external conditions, have been obtained using system identification method. Comparison with earlier control techniques is included. The results show that the proposed EO control strategy results in significant reduction of energy losses compared to the existing ones.     

Mixed Discontinuous Galerkin Finite Element Method for the Biharmonic Equation

In this paper, we first split the biharmonic equation Δ² u=f with nonhomogeneous essential boundary conditions into a system of two second order equations by introducing an auxiliary variable v=Δu and then apply an hp-mixed discontinuous Galerkin method to the resulting system. The unknown approximation v _h of v can easily be eliminated to reduce the discrete problem to a Schur complement system in u _h , which is an approximation of u. A direct approximation v _h of v can be obtained from the approximation u _h of u. Using piecewise polynomials of degree p≥3, a priori error estimates of u−u _h in the broken H ¹ norm as well as in L ² norm which are optimal in h and suboptimal in p are derived. Moreover, a priori error bound for v−v _h in L ² norm which is suboptimal in h and p is also discussed. When p=2, the preset method also converges, but with suboptimal convergence rate. Finally, numerical experiments are presented to illustrate the theoretical results. Supported by DST-DAAD (PPP-05) project.     

Obstacle Avoidance for Spatial Hyper‐Redundant Manipulators Using Harmonic Potential Functions and the Mode Shape Technique

This paper deals with the obstacle avoidance problem for spatial hyper‐redundant manipulators in known environments. The manipulator is divided into two sections, a proximal section that has not entered the space among the obstacles and a distal section among the obstacles. Harmonic potential functions are employed to achieve obstacle avoidance for the distal section in three‐dimensional space in order to avoid local minima in cluttered environments. A modified panel method is used to generate the potential of any arbitrary shaped obstacle in three‐dimensional space. An alternative backbone curve concept and an efficient fitting method are introduced to control the trajectory of proximal links. The fitting method is recursive and avoids the complications involved with solving large systems of nonlinear algebraic equations. The combination of a three‐dimensional safe path derived from the harmonic potential field and the backbone curve concept leads to an elegant kinematic control strategy that guarantees obstacle avoidance. © 2003 Wiley Periodicals, Inc.     

Influence of Sb/As soak times on the structural and optical properties of GaAsSb/GaAs interfaces

The effects of Sb/As soak times, prior to growth of GaAsSb on GaAs were investigated by High Resolution X-Ray Diffraction (HRXRD) and photoluminescence (PL). Multiple quantum well samples with soak times of 0 s, 30 s and 60 s were grown at 500 °C with nominally identical Sb and As fluxes. HRXRD results show that a 30 s soak minimizes diffuse scattering seen around superlattice peaks in the reciprocal space maps, an effect attributed to corrugations in the GaAs-GaAsSb interface. An inferred band diagram calculated using a four band k.p model and modified taking into account the HRXRD results was used to explain PL spectra taken for each sample at 80 K. It is concluded that an optimum soak time exists for GaASb growth on GaAs, determined by the growth conditions.     

Effect of pH on the physicochemical properties of starch films

We demonstrate a simple approach of using highly alkaline starch solutions to obtain films with high flexibility and improved water resistance. Extensive studies have been done to develop films from starch, primarily for food applications. However, films developed from starch are brittle and generally chemical modifications or plasticizers are used to improve the flexibility and other properties of starch films. Such modifications make starch expensive, decrease biodegradability, and affect the morphology and subsequent processing of starch. In this research, we have prepared films using starch solutions at pH between 3 and 11. Starch solutions having different pHs were made into films and the tensile, thermal properties, and resistance to water were studied. It was found that preparing starch with pH 11 solution imparts high flexibility without any apparent physical damage. Films prepared under strong acidic and alkaline conditions also had considerably reduced hydrophilicity, which is required for food packaging and other applications. The films prepared at alkaline pH show nearly 50% reduction in water sorption and an increase in elongation. The films obtained from alkaline pH are flexible and water resistant and can potentially be used to develop various bioproducts. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48563.