Experimental and Theoretical Study of the Stress and Strain Fields Around Fatigue Cracks and Plasticity-Induced Crack Closure

This work investigates experimentally and theoretically the local crack tip stress and strain fields, and plasticity-induced crack closure acting on the crack flanks behind the crack tip, in fine-grained aluminium alloy 5091 (Al-Mg-Li-C-O) compact tension fatigued specimens. Compressive residual stresses ahead of the crack tip and plasticity-induced crack closure are often attributed to be the two main mechanisms responsible for crack growth retardation. Specimens investigated were prepared: with constant amplitude fatigue; with constant amplitude fatigue followed by a single overload; and finally with constant amplitude fatigue followed by a single overload followed by further constant amplitude fatigue. Experimental crack tip strain (and hence stress) measurements have been carried out along the midthickness of the specimens using energy dispersive X-ray diffraction (EDXRD) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. The very small grain size of aluminium alloy 5091 allows minimization of the sampling volume in order to maximize the spatial resolution achievable with EDXRD. High spatial resolution is essential for measuring highly localized crack tip stresses. For theoretical investigations of the crack tip stress and strain fields, existing analytical solution (Westergaard, 1939) and the finite element code ABAQUS (ABAQUS Inc., 2004) have been used. Crack closure has been investigated by finite element analysis and compliance experimental technique. Finite element analyses for both stress fields and crack closure have been carried out in plane stress and plane strain. A possible link between the stresses ahead of the crack tip and the plasticity-induced crack closure on the crack flanks behind the crack tip has been investigated

The Influence of Service Quality and Price on Customer Satisfaction: An Empirical Study on Restaurant Services in Khulna Division

One of the vital needs of increasing population in our country is food. There are a few number of restaurant goers to meet the necessity of food. Most of the people in our country occasionally go to the restaurant to enjoy ethnic and some of western food items. The main purpose of this study is to identify some key drivers of customer satisfaction on restaurant services. The study covers the opinion of restaurant goers in Khulna region. This research is based on empirical study. Primarily, researchers contacted with 450 customers for their valuable opinion regarding restaurant services. But, 246 customers gave their spontaneous response in this regard. Chi-square test has been applied for testing hypothesizes by using SPSS software. This study aims to link some factors of service quality and price fairness of restaurant with the customers' satisfaction. The researchers find out that customers of restaurant have negative impression about product and service quality fairness, price fairness, staff's service, environment of the restaurant, image of the restaurant and loyalty of the restaurant. The researchers suggest emphasizing on those critical issues to attract new customers and retain existing customers. Keywords: Customer Satisfaction, Customer Loyalty, Service Qualit

π拡張アリールアルコールの配位したスズ(Ⅳ)ポルフィリンの合成研究

首都大学東京, 2019-09-30, 博士（理学）首都大学東

Crack tip plasticity in mixed mode loading under contained yielding conditions

Mode I, mode II and mixed mode I/II asymptotic crack tip fields have been studied under contained yielding conditions using plane strain and plane stress boundary layer formulations. The effect of the non-singular term in the asymptotic elastic expansion (Williams, 1957) on the plastic zone at the crack tip has been determined. Plane stress mode I, mode II and mixed mode I/II crack tip fields have also been investigated analytically. Analytical solutions were developed by assembling constant stress, fan and elastic sectors. Slip line theory (Hill, 1950) was used to solve constant stress and fan sectors while the stress fields in elastic sectors were solved using the semi-infinite wedge solution of Timoshenko and Goodier (1970). Analytical solutions were validated by numerical results, and represented as slip line fields

Coming Stakes in the Ocean: Food Production, Shipping and Trade, Tourism, Ecosystem-biodiversity, New Technologies and Climate Change Challenges in Bangladesh

Blue economy is an emerging concept in all over the world where Bangladesh is not in exception. The blue economy of Bangladesh is subject to multiple interlinked activities. Among the major activities, food production, shipping and trade, tourism, ecosystem-biodiversity, new technologies and climate change challenges are the most promising sectors which are discussed in this chapter to project the present and future potential, constrains, ways to overcome in the context of the blue economy of Bangladesh following various published literatures. The review has revealed that Bangladesh has enormous resources which have great potential to uplift the existing economy, improving livelihoods, while significantly reducing environmental risks and ecological scarcities. However, there are lot of constrains which hinder to get the ultimate fruit from these potentialities. The major constrains include lack of policy, institutional or organizational structure and coordination, data or information, knowledge in innovating and diversifying marine products and services, marketing strategies, continuous scientific research, skilled manpower with motivation and dedication, public awareness, maritime security and concern in marine and coastal environment. Initiations to overcome these constrains with long and short term strategic plans and properly implementing the strategic decisions will bring the state more productive and could be a model country with blue economy approach

Introduction of emergency contraception in Bangladesh: Using operations research for policy decisions

The Directorate of Family Planning, Bangladesh, the Population Council, Pathfinder International, and John Snow Incorporated collaborated to conduct this operations research study to assess the acceptability and feasibility of providing emergency contraception pills (ECP) as a backup support to existing family planning methods. The study demonstrated that all categories of health providers, including NGO outreach workers, could be effectively trained to provide ECP services. The study also demonstrated high acceptability of ECP and revealed that if used correctly, the success rate in avoiding unwanted pregnancy was extremely high. The positive findings of the study have helped the Ministry of Health and Family Welfare, Government of Bangladesh, to approve introduction of ECP in the National Family Planning Program. The present study thus also serves as a good demonstration of how operations research can contribute in policy decisions and how research findings can be translated into action