Effective Simulation and Optimization of a Laser Peening Process

Laser peening (LP) is a surface enhancement technique that has been applied to improve fatigue and corrosion properties of metals. The ability to use a high energy laser pulse to generate shock waves, inducing a compressive residual stress field in metallic materials, has applications in multiple fields such as turbomachinery, airframe structures, and medical appliances. In the past, researchers have investigated the effects of LP parameters experimentally and performed a limited number of simulations on simple geometries. However, monitoring the dynamic, intricate relationships of peened materials experimentally is time consuming, expensive, and challenging. With increasing applications of LP on complex geometries, these limited experimental and simulation capabilities are not sufficient for an effective LP process design. Due to high speed, dynamic process parameters, it is difficult to achieve a consistent residual stress field in each treatment and constrain detrimental effects. With increased computer speed as well as increased sophistication in non-linear finite element analysis software, it is now possible to develop simulations that can consider several LP parameters. In this research, a finite element simulation capability of the LP process is developed. These simulations are validated with the available experimental results. Based on the validated model, simplifications to complex models are developed. These models include quarter symmetric 3D model, a cylindrical coupon, a parametric plate, and a bending coupon model. The developed models can perform simulations incorporating the LP process parameters, such as pressure pulse properties, spot properties, number of shots, locations, sequences, overlapping configurations, and complex geometries. These models are employed in parametric investigations and residual stress profile optimization at single and multiple locations. In parametric investigations, quarter symmetric 3D model is used to investigate temporal variations of pressure pulse, pressure magnitude, and shot shape and size. The LP optimization problem is divided into two parts: single and multiple locations peening optimization. The single-location peening optimization problems have mixed design variables and multiple optimal solutions. In the optimization literature, many researchers have solved problems involving mixed variables or multiple optima, but it is difficult to find multiple solutions for mixed-variable problems. A mixed-variable Niche Particle Swarm Optimization (MNPSO) is proposed that incorporates a mixed-variable handling technique and a niching technique to solve the problem. Designing an optimal residual stress profile for multiple-location peening is a challenging task due to the computational cost and the nonlinear behavior of LP. A Progressive Multifidelity Optimization Strategy (PMOS) is proposed to solve the problem. The three-stage PMOS, combines low- and high- fidelity simulations and respective surrogate models and a mixed-variable handling strategy. This strategy employs comparatively low computational-intensity models in the first two stages to locate the design space that may contain the optimal solution. The third stage employs high fidelity simulation and surrogate models to determine the optimal solution. The overall objective of this research is to employ finite element simulations and effective optimization techniques to achieve optimal residual stress fields

Development and validation of resource flexibility measures for manufacturing industry

Purpose: Global competition and ever changing customers demand have made manufacturing organizations to rapidly adjust to complexities, uncertainties, and changes. Therefore, flexibility in manufacturing resources is necessary to respond cost effectively and rapidly to changing production needs and requirements. Ability of manufacturing resources to dynamically reallocate from one stage of a production process to another in response to shifting bottlenecks is recognized as resource flexibility. This paper aims to develop and validate resource flexibility measures for manufacturing industry that could be used by managers/ practitioners in assessing and improving the status of resource flexibility for the optimum utilization of resources. Design/methodology/approach: The study involves survey carried out in Indian manufacturing industry using a questionnaire to assess the status of various aspects of resource flexibility and their relationships. A questionnaire was specially designed covering various parameters of resource flexibility. Its reliability was checked by finding the value of Cronback alpha (0.8417). Relative weightage of various measures was found out by using Analytical Hierarchy Process (AHP). Pearson’s coefficient of correlation analysis was carried out to find out relationships between various parameters. Findings: From detailed review of literature on resource flexibility, 17 measures of resource flexibility and 47 variables were identified. The questionnaire included questions on all these measures and parameters. ‘Ability of machines to perform diverse set of operations’ and ability of workers to work on different machines’ emerged to be important measures with contributing weightage of 20.19% and 17.58% respectively. All the measures were found to be significantly correlated with overall resource flexibility except ‘training of workers’, as shown by Pearson’s coefficient of correlation. This indicates that companies do not want to spend on worker training. Practical implications: The study provides guidelines to managers/ practitioners in assessing and managing resource flexibility for optimum utilization of resources. This study can also help the firm’s management to identify the measures and variables to manage resource flexibility and the order in which stress should be given to various measures and actions. The developed and validated measures can be used globally for managing the resource flexibility in manufacturing sector. Originality/value: In this work, the theoretical perspective has been used to prepare the instrument from a detailed review of literature and then the study carried out using the questionnaire in an area where such studies were not carried out earlier.Peer Reviewe

Comparison of multi-modal optimization algorithms based on evolutionary algorithms

Many engineering optimization tasks involve finding more than one optimum solution. The present study provides a comprehensive review of the existing work done in the field of multi-modal function optimization and provides a critical analysis of the existing methods. Existing niching methods are analyzed and an improved niching method is proposed. To achieve this purpose, we first give an introduction to niching and diversity preservation, followed by discussion of a number of algorithms. Thereafter, a comparison of clearing, clustering, deterministic crowding, probabilistic crowding, restricted tournament selection, sharing, species conserving genetic algorithms is made. A modified niching-based technique-modified clearing approach-is introduced and also compared with existing methods. For comparison, a versatile hump test function is also proposed and used together with two other functions. The ability of the algorithms in finding, locating, and maintaining multiple optima is judged using two performance measures: (i) number of peaks maintained, and (ii) computational time. Based on the results, we conclude that the restricted tournament selection and the proposed modified clearing approaches are better in terms of finding and maintaining the multiple optima

ASSESSMENT OF INFORMATION AND COMPUTER LITERACY SKILLS AMONG THE STUDENTS OF THE UNIVERSITY OF JAMMU: A CASE STUDY

This study was organized to assess and have records about the information literacy and computer literacy skills among the students at the University of Jammu. To collect the data, a questionnaire was framed and distributed among 265 students studying at the University of Jammu. Out of 265 students, 243 questionnaires were received with responses being filed in them. Of the 243 students, there were 159 males and 84 females. The data revealed that the majority of the students 177 (72.84%) were familiar with the concept of computer and digital literacy and most of the students possess knowledge about the basic ICT skills such as Word Application software, Multimedia Applications, Spreadsheets Applications, and Communication Applications, etc. through which they can keep themselves abreast and updated with any sort of information required

Dynamics of carbon pool in Oak dominated community forests of District Tehri Garhwal, Uttarakhand, India

The present study was carried out community forest of Tehri Garhwal Uttarakhand. The amount of growing stock volume density in the study region were ranges between 28.21 m3/ha and 44.59 m3/ha, above-ground biomass density ranges between 200.59 Mg ha-1 and 238.44 Mg ha-1, belowground biomass density range between 128.03 and 192.96 Mg/ha, total biomass density was in the range of 287.76 and 431.40 Mg ha-1 and total carbon density ranges between 162.40 and 194.13 Mg ha-1. The isolation of total biomass density into aboveground and belowground parts showed a similar pattern in every one of the forest locales. Present study proposes that community forests play a vital role in ecosystem health they are playing their job quietly in the moderation of environmental carbon and crucial for future planning. Loss of old community forestry system is centre for concern to the forest department, forest rangers and forestry researchers. Protection of community forests is an urgent need for the maintenance of community ecosystem in temperate region of Garhwal Himalaya Uttarakhand. Preservation of the both young and old growth forests is the best way to adapt to environmental change and a worldwide temperature alteration. As we probably are aware the pattern of old cultivating in the networks close to the urban communities is decrease and will be supplanted by present day procedures so we need to look through some new strategy and execution to monitor the old cultivating methods. The ground stock volume density shows moderate positive correlation with altitude (r =0.325) while above ground biomass density (r = 0.203) below ground biomass density, total biomass density and total carbon density shows week positive correlation with altitude (r =0.117, r = 0.194 and r = 0.194 respectively). The Linear regression shows that ground stock volume density, above ground biomass density, below ground biomass density, total biomass density  and total carbon density  not dependent only altitude some other factor affecting them. While as above ground biomass density show highly positive correlation with total biomass density and total carbon density whereas altitude show less positive correlation with below ground biomass density)

Antibacterial activity of leaf extracts of some selected traditional medicinal plants of Uttarakhand, North East India

Screenings of methanolic leaf extracts of nine medicinal plants (Cotinus coggygria, Adhatoda vesica, Argemone mexicana, Zanthoxylum armatum, Berberis asiatica, Corissa opaca, Euphorbia hirta, Cassio fistula and Ricinus communis), belonging to selected areas of Uttarakhand, were tested against seven bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Enterobactor aerogenes, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa) by disc diffusion method. Leaf extracts of R. communis, B. asiatica and C. opaca showed high (13 – 23) effect on all the bacterial strains while E. hirta, Z. armatum and A. vesica exhibits minimum (6 – 15) effects. Remaining leaf extracts of plants were found moderately (10 - 19) effective

SYNTHESIS AND CHARACTERIZATION OF TI (III), V (III),VO (IV), MOO (V),FE (II) AND FE (III) COMPLEXES OF BENZIL- 2,4-DINITROPHENYL HYDRAZONE P-BROMO ANILINE

The complexes of Benzil-2, 4-dinitrophenyl hydrazone-p- bromo aniline with Ti(III),V(III), VO(IV),MoO (V), Fe(II), Fe(III) have synthesized and characterized by elemental analysis, magnetic measurement data, molar conductance, TGA,UV-visible and IR spectra data. The complexes of Ti (III), V (III), Fe (II) and Fe (III) have octahedral geometry while VO (IV) and MoO(V) have distorted octahedral geometry due to the presence of M=O moiety