Effects of surface finish and treatment on the fatigue behaviour of vibrating cylinder block using frequency response approach     

RAHMAN M. M. ARIFFIN A. K. 《浙江大学学报(A卷英文版)》2006,7(3):352-360

INTRODUCTION Due to market pressures for improvements in productivity, reliability, ductility, wear resistance and profitability of mechanical systems, manufacturers are placing increasing demands on available materials.Economic constraints require that these materials are inexpensive and easily available. In order to enhance the surface properties of today’s materials, producers of components are turning to different surface finish and treatments. There are several techniques available …  相似文献   

Investigation of a novel perforation technique in petroleum wells—perforation by drilling     

M.A. Rahman  J. Biazar  M.R. Islam 《Journal of The Franklin Institute》2007,344(5):777-789

The objective of perforating the petroleum wells is to maximize well productivity. A good connectivity between the wellbore and formation can lead up to achieve that goal. However, the conventional method of perforation, which basically involves the use of explosive charges, rarely meets the expected well productivity. It is mainly because of the formation of a region of reduced permeability around the perforation tunnel. To offset such and several other shortcomings of present practices, a new technique is required, the highlight of this paper. Described as the ‘perforation by drilling’ (PD), this new technique is examined and compared for its performance with that of another technique, ‘Perforation by Shooting’ (PS). For this, the experimental and numerical results of the PS technique on cylindrical sand samples of varying amounts of strength and porosity are studied. Moreover, in order to achieve a so-called ‘perfect perforation’, results are compared with the ‘Casting technique’. Three different samples were selected for the measurement of fluid flow rate and differential pressure across the perforation using a ‘geotechnical digital system’ (GDS), which is a triaxial testing device. Profiles such as fluid flow rate with a change in differential pressure and pressure build-up data with time, signify that the PD technique can achieve maximum wellbore productivity when compared to the PS technique. Results also indicate that at a 100 kPa differential pressure, the PS, PD and Casting techniques can achieve 0.20, 0.65 and 1.00 mL/s fluid flow rates respectively across a sample. The paper also implements a 1-D time dependent porous media flow model to simulate flow across the perforated cylindrical samples created by the PS, PD and Casting techniques. Results show a good consistency between the experimental and numerical approaches.  相似文献   

Childhood Maltreatment,Gender Nonconformity,and Adolescent Sexual Orientation: A Prospective Birth Cohort Study     

Yin Xu  Sam Norton  Qazi Rahman 《Child development》2020,91(4):e984-e994

This study tested whether associations between childhood maltreatment and adolescent sexual orientation were accounted for by childhood gender nonconforming behavior (GNCB) in a prospective birth cohort (N = 5,007). Childhood parental maltreatment (physical and emotional) and GNCB were assessed on multiple occasions up to age 6 years, and sexual orientation at 15.5 years. Boys with a history of maltreatment were significantly more likely to be nonheterosexual. Using propensity score weighting, maltreatment was associated with a 3.5% (p = .03) increase in the prevalence of nonheterosexuality accounting for confounders not including GNCB, and by 2.9% (p = .06) when also accounting for GNCB. These findings suggest that maltreatment is associated with an increased prevalence of nonheterosexuality in boys but may be explained by confounding factors including GNCB.  相似文献   

Exploring the Meanings of Hijab through Online Comments in Canada     

Osmud Rahman  Benjamin Fung  Alexia Yeo 《Journal of Intercultural Communication Research》2016,45(3):214-232

Controversies surrounding ethnic dress such as hijab have increased public awareness about cultural diversity. The number of comments posted on online media make it evident that many people are concerned about ethnic attire, cultural differences and social cohesion. Although researchers have examined the meanings of veiling, the relationships between hijab and public opinion have seldom been investigated. The overarching objective of this study was to understand the relationships between Islamic attire and online readers’ opinion. In light of the limitations in the previous studies on this topic, this study attempts to fill the gap by studying posters’ opinions toward hijab through publicly available online information in the form of posted comments.  相似文献   

Educational developments in Asia     

A. F. M. K. Rahman 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1963,8(3-4):257-275

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An investigation on allocative efficiency and implications of new funding plans for the Australian universities     

Shamsul Arifeen Khan Mamun  Mohammand Mafizur Rahman 《Educational Research for Policy and Practice》2016,15(1):71-82

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A Query Expansion Framework in Image Retrieval Domain Based on Local and Global Analysis     

Rahman MM  Antani SK  Thoma GR 《Information processing & management》2011,47(5):676-691

We present an image retrieval framework based on automatic query expansion in a concept feature space by generalizing the vector space model of information retrieval. In this framework, images are represented by vectors of weighted concepts similar to the keyword-based representation used in text retrieval. To generate the concept vocabularies, a statistical model is built by utilizing Support Vector Machine (SVM)-based classification techniques. The images are represented as "bag of concepts" that comprise perceptually and/or semantically distinguishable color and texture patches from local image regions in a multi-dimensional feature space. To explore the correlation between the concepts and overcome the assumption of feature independence in this model, we propose query expansion techniques in the image domain from a new perspective based on both local and global analysis. For the local analysis, the correlations between the concepts based on the co-occurrence pattern, and the metrical constraints based on the neighborhood proximity between the concepts in encoded images, are analyzed by considering local feedback information. We also analyze the concept similarities in the collection as a whole in the form of a similarity thesaurus and propose an efficient query expansion based on the global analysis. The experimental results on a photographic collection of natural scenes and a biomedical database of different imaging modalities demonstrate the effectiveness of the proposed framework in terms of precision and recall.  相似文献   

Back to Basics: A Bilingual Advantage in Infant Visual Habituation          下载免费PDF全文

Leher Singh  Charlene S. L. Fu  Aishah A. Rahman  Waseem B. Hameed  Shamini Sanmugam  Pratibha Agarwal  Binyan Jiang  Yap Seng Chong  Michael J. Meaney  Anne Rifkin‐Graboi  the GUSTO Research Team 《Child development》2015,86(1):294-302

Comparisons of cognitive processing in monolinguals and bilinguals have revealed a bilingual advantage in inhibitory control. Recent studies have demonstrated advantages associated with exposure to two languages in infancy. However, the domain specificity and scope of the infant bilingual advantage in infancy remains unclear. In the present study, 114 monolingual and bilingual infants were compared in a very basic task of information processing—visual habituation—at 6 months of age. Bilingual infants demonstrated greater efficiency in stimulus encoding as well as in improved recognition memory for familiar stimuli as compared to monolinguals. Findings reveal a generalized cognitive advantage in bilingual infants that is broad in scope, early to emerge, and not specific to language.  相似文献   

Translating Knowledge into Action at the Norwegian University of Life Sciences (UMB)     

Trine Lund  Charles Francis  Kristin Pederson  Geir Lieblein  Md. Hafizur Rahman 《The Journal of Agricultural Education and Extension》2013,19(5):537-554

Abstract

Purpose: This article explores the impacts of action learning on graduates’ abilities to use interdisciplinary knowledge to solve problems, practice teamwork on the job and become change agents through study in two MSc programmes at the Norwegian University of Life Sciences (UMB).

Design/methodology/approach: Electronic questionnaires were sent to students who had graduated from the Agroecology and Management of Natural Resources and Sustainable Agriculture (MNRSA) MSc programmes between 2000 and 2007.

Findings: Both study programmes encouraged students to become change agents promoting sustainable practices through application of knowledge and methods from natural and social sciences. Agroecology graduates applied a greater range of creative research methods, and improved their capacity for holistic and systems thinking more than MNRSA graduates, while the latter were more skilled in building consensus. Graduates from both programmes increased their abilities to create a positive team environment, bring people together to express their views and take multiple views into consideration when making decisions.

Practical implications: This survey documents how action learning develops students’ skills and knowledge to handle complex social and environmental challenges and become change agents.

Originality/value: In the context of increasing challenges in agroecology and natural resource management the findings on how to translate knowledge into action are important for teaching/learning institutions dealing with education for sustainable development.  相似文献   

A blended learning approach to teach fluid mechanics in engineering     

Ataur Rahman 《European Journal of Engineering Education》2017,42(3):252-259

This paper presents a case study on the teaching and learning of fluid mechanics at the University of Western Sydney (UWS), Australia, by applying a blended learning approach (BLA). In the adopted BLA, various flexible learning materials have been made available to the students such as online recorded lectures, online recorded tutorials, hand written tutorial solutions, discussion board and online practice quizzes. The lecture and tutorial class times have been primarily utilised to discuss confusing topics and engage students with practical issues in applying the theories learnt in fluid mechanics. Based on the data of over 734 students over a 4-year period, it has been shown that a BLA has improved the learning experience of the fluid mechanics students in UWS. The overall percentage of student satisfaction in this subject has increased by 18% in the BLA case compared with the traditional one.  相似文献