901 resultados para Special tooling and machining


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Every closed, oriented, real analytic Riemannian 3-manifold can be isometrically embedded as a special Lagrangian submanifold of a Calabi-Yau 3-fold, even as the real locus of an antiholomorphic, isometric involution. Every closed, oriented, real analytic Riemannian 4-manifold whose bundle of self-dual 2-forms is trivial can be isometrically embedded as a coassociative submanifold in a G_2-manifold, even as the fixed locus of an anti-G_2 involution. These results, when coupled with McLean's analysis of the moduli spaces of such calibrated submanifolds, yield a plentiful supply of examples of compact calibrated submanifolds with nontrivial deformation spaces.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The thesis focuses on military crisis management and strategy.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Cold roll forming of thin-walled sections is a very useful process in the sheet metal industry. However, the conventional method for the design and manufacture of form-rolls, the special tooling used in the cold roll forming process, is a very time consuming and skill demanding exercise. This thesis describes the establishment of a stand-alone minicomputer based CAD/CAM system for assisting the design and manufacture of form-rolls. The work was undertaken in collaboration with a leading manufacturer of thin-walled sections. A package of computer programs have been developed to provide computer aids for every aspect of work in form-roll design and manufacture. The programs have been successfully implemented, as an integrated CAD/CAM software system, on the ICL PERQ minicomputer with graphics facilities. Thus, the developed CAD/CAM system is a single-user workstation, with software facilities to help the user to perform the conventional roll design activities including the design of the finished section, the flower pattern, and the form-rolls. A roll editor program can then be used to modify, if required, the computer generated roll profiles. As far as manufacturing is concerned, a special-purpose roll machining program and postprocessor can be used in conjunction to generate the NC control part-programs for the production of form-rolls by NC turning. Graphics facilities have been incorporated into the CAD/CAM software programs to display drawings interactively on the computer screen throughout all stages of execution of the CAD/CAM software. It has been found that computerisation can shorten the lead time in all activities dealing with the design and manufacture of form-rolls, and small or medium size manufacturing companies can gain benefits from the CAD/CM! technology by developing, according to its own specification, a tailor-made CAD/CAM software system on a low cost minicomputer.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this paper, manufacturability analysis and collection of design aspects is made for a microwave test-fixture. Aspects of applying systematic design for a microwave test-fixture design and manufacturing are also analysed. Special questionnaires for the component and machining are made in order to enable necessary information to ensure DFM(A) – aspects of the component. The aspects of easy manufacturing for machining the microwave test-fixture are collected. Material selection is discussed and manufacturing stages of prototype manufacturing are presented.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Implementation of different policies and plans aiming at providing education for all is a challenge in Tanzania. The need for educators and professionals with relevant knowledge and qualifications in special education is substantial. Teacher education does not equip educators with sufficient knowledge and skills in special education and professional development programs in special education are few in number. Up to 2005 no degree programs in special education at university level were available in Tanzania. The B.Ed. Special Education program offered by the Open University of Tanzania in collaboration with Åbo Akademi University in Finland was one of the efforts aimed at addressing the big national need for teachers and other professionals with degree qualifications in special education. This pilot program offered unique possibilities to study professional development in Tanzania. The research group in this study consisted of the group of students who participated in the degree program 2005-2007. The study is guided by three theoretical perspectives: individual, social and societal. The individual perspective emphasizes psychological factors as motives, motivation, achievement, self-directed behavior and personal growth. Within social perspective, professional development is viewed as situated within the social and cultural context. The third perspective, the societal, focuses on change, reforms, innovations and transformation of school systems and societies. Accordingly, professional development is viewed as an individual, social and societal phenomenon. The overall aim of the study is to explore the participants’ motives for participating in a B.Ed. Special Education program and the perceived outcomes of the program in terms of professional development. In order to achieve the objectives of the study, a case study approach was adopted. Questionnaires and semi-structured interviews were administered in three waves between January 2007 and February 2009 to the 35 educators participating in the B.Ed. Special Education program. The findings of the study reveal that the participants expressed motives which were related to job performance, knowledge, skills, academic degree and career. Also altruistic motives were expressed by the participants in terms of helping and supporting students with special needs and their communities. The perceived outcomes of the program were in line with the expressed motives. However, the results indicate that the participants also learned new skills, as interaction skills and guidance and counseling skills. Increased self-confidence was also mentioned as an outcome. The participants also got deepened understanding of disability issues. In addition, they learned strategies for creating awareness of persons with disability in the communities. Thus the findings of the study indicate positive outcomes of the program in terms of professional development. The conclusion of the study is that individual, social and societal factors interact when it comes to explaining why Tanzanian educators in special education choose to pursue a degree program in special education. The individual motives, as increased knowledge and better prospects of career development interact with the social and societal motives to help and support vulnerable student groups. The study contributes to increased understanding of the complexity of professional development and of the realities educators meet when educational reforms are implemented in a developing country.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Automotive parts manufacture by machining process using silicon nitride-based ceramic tool development in Brazil already is a reality. Si 3N4-based ceramic cutting tools offer a high productivity due to their excellent hot hardness, which allows high cutting speeds. Under such conditions the cutting tool must be resistant to a combination of mechanical, thermal and chemical attacks. Silicon nitride based ceramic materials constitute a mature technology with a very broad base of current and potential applications. The best opportunities for Si3N 4-based ceramics include ballistic armor, composite automotive brakes, diesel particulate filters, joint replacement products and others. The goal of this work was to show latter advance in silicon nitride manufacture and its recent evolution on machining process of gray cast iron, compacted graphite iron and Ti-6Al-4V. Materials characterization and machining tests were analyzed by X-Ray Diffraction, Scanning Electron Microscopy, Vickers hardness and toughness fracture and technical norm. In recent works the authors has been proved to advance in microstructural, mechanical and physic properties control. These facts prove that silicon nitride-based ceramic has enough resistance to withstand the impacts inherent to the machining of gray cast iron (CI), compacted graphite iron (CGI) and Ti-6Al-4V (6-4). Copyright © 2008 SAE International.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Includes bibliography

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Many countries treat income generated via exports favourably, especially when production takes places in special zones known as export processing zones (EPZs). EPZs can be defined as specific, geographically defined zones or areas that are subject to special administration and that generally offer tax incentives, such as duty‐free imports when producing for export, exemption from other regulatory constraints linked to import for the domestic market, sometimes favourable treatment in terms of industrial regulation, and the streamlining of border clearing procedures. We describe a database of WTO Members that employ special economic zones as part of their industrial policy mix. This is based on WTO notification and monitoring through the WTO’s trade policy review mechanism (TPRM), supplemented with information from the ILO, World Bank, and primary sources. We also provide some rough analysis of the relationship between use of EPZs and the carbon intensity of exports, and relative levels of investment across countries with and without special zones.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Computer integrated manufacture has brought about great advances in manufacturing technology and its recognition is world wide. Cold roll forming of thin-walled sections, and in particular the design and manufacture of form-rolls, the special tooling used in the cold roll forming process, is but one such area where computer integrated manufacture can make a positive contribution. The work reported in this thesis, concerned with the development of an integrated manufacturing system for assisting the design and manufacture of form-rolls, was undertaken in collaboration with a leading manufacturer of thin-walled sections. A suit of computer programs, written in FORTRAN 77, have been developed to provide computer aids for every aspect of work in form-roll design and manufacture including cost estimation and stock control aids. The first phase of the development programme dealt with the establishment of CAD facilities for form-roll design, comprising the design of the finished section, the flower pattern, the roll design and the interactive roll editor program. Concerning the CAM facilities, dealt with in the second phase, an expert system roll machining processor and a general post-processor have been developed for considering the roll geometry and automatically generating NC tape programs for any required CNC lathe system. These programs have been successfully implemented, as an integrated manufacturing software system, on the VAX 11/750 super-minicomputer with graphics facilities for displaying drawings interactively on the terminal screen. The development of the integrated system has been found beneficial in all aspects of form-roll design and manufacture. Design and manufacturing lead times have been reduced by several weeks, quality has improved considerably and productivity has increased. The work has also demonstrated the promising nature of the expert systems approach to computer integrated manufacture.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Full text This Proceedings volume contains selected papers from the Fourth International CIRP-sponsored, Conference on Digital Enterprise Technology (DET2007), which was held at the University of Bath, UK, 19–21 September 2007. All selected papers have been suitably enhanced for publication in the Journal and have undergone full review. Digital enterprise technology (DET) is ‘the collection of systems and methods for the digital modelling and analysis of the global product development and realization process, in the context of lifecycle management.’ The principal aim of the DET concept is to provide a coherent context for the development and integration of the various digital technologies that underpin modern design and manufacturing. These technologies can be classified according to the following five key areas. 1. Distributed and collaborative design. 2. Process modelling and process planning. 3. Advanced factory design and modelling. 4. Physical-to-digital environment integrators–verification. 5. Enterprise integration technologies. This special issue is representative of the wide breadth of the DET concept including; a comprehensive review of digital engineering, design processes, digital modelling of machine tools, forming, robotics and machining processes, verification and metrology, and dynamic networks. It is particularly pleasing to see the development of metrology as a key aspect of modern manufacturing technology, linking design intent to process capability. The papers published herein will facilitate the exploration of new and evolving research concepts by the international research community and will influence the development of international standards for the application of DET technologies.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The rewards and sanctions associated with high-stakes testing may induce educators to participate in practices that will ensure the elimination of the scores of low-achieving students from the testing pool. Two ways in which scores may be eliminated is through retention or referral to special education. ^ This study examined the use of these practices at 179 elementary schools in Miami-Dade County Public Schools, the 4th largest school district in the country. Between- and within-subjects designs were analyzed using repeated measures analysis of variance to compare retention and referral to special education practices over a five-year period of time, two years prior to and two years after the implementation of Florida's high-stakes test, the Florida Comprehensive Assessment Test, FCAT. ^ Significant main effects for referral and retention over time were demonstrated. The use of retention steadily increased over the first three years, with its usage maintained during the fourth year. While the use of referral actually decreased from the first to second years, a significant change occurred after the implementation of the FCAT. ^ Examination of the use of these practices according to student and school characteristics revealed significant differences. Increases in the use of referral across time was significant for Black, non-Hispanic and Hispanic students, all limited English proficiency population categories, medium and low socioeconomic status category schools, all grade levels, and for schools with accountability grades of A. C, D and F with the most striking absolute increase occurring for F schools. Increases in the use of retention across time were significant for all ethnic groups, limited English proficiency categories, and socioeconomic status categories, for grades kindergarten through four and by gender. Significant increases occurred for schools with accountability performance grades of C, D and F; however the most dramatic increase occurred for the F schools. A direct relationship between performance category grade of school and their use of retention was demonstrated. The results suggest that schools changed their use of referral and retention in response to the implementation of the FCAT. ^

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The rewards and sanctions associated with high-stakes testing may induce educators to participate in practices that will ensure the elimination of the scores of low-achieving students from the testing pool. Two ways in which scores may be eliminated is through retention or referral to special education. This study examined the use of these practices at 179 elementary schools in Miami-Dade County Public Schools, the 4th largest school district in the country. Between- and within-subjects designs were analyzed using repeated measures analysis of variance to compare retention and referral to special education practices over a five-year period of time, two years prior to and two years after the implementation of Florida's high-stakes test, the Florida Comprehensive Assessment Test, FCAT. Significant main effects for referral and retention over time were demonstrated. The use of retention steadily increased over the first three years, with its usage maintained during the fourth year. While the use of referral actually decreased from the first to second years, a significant change occurred after the implementation of the FCAT. Examination of the use of these practices according to student and school characteristics revealed significant differences. Increases in the use of referral across time was significant for Black, non-Hispanic and Hispanic students, all limited English proficiency population categories, medium and low socioeconomic status category schools, all grade levels, and for schools with accountability grades of A, C, D and F with the most striking absolute increase occurring for F schools. Increases in the use of retention across time were significant for all ethnic groups, limited English proficiency categories, and socioeconomic status categories, for grades kindergarten through four and by gender. Significant increases occurred for schools with accountability performance grades of C, D and F; however the most dramatic increase occurred for the F schools. A direct relationship between performance category grade of school and their use of retention was demonstrated. The results suggest that schools changed their use of referral and retention in response to the implementation of the FCAT.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This study investigated the empathy of Special Education graduate students in the USA and the Bahamas, and of Counseling and Organizational Learning students. About 180 students were administered the Interpersonal Reactivity Index to assess: fantasy, perspective taking, empathetic concern, and personal distress. Significant differences existed by major and country.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Research on gender and diversity has taken longer than usual to develop in Portuguese academia. Different explanations can be provided for the apparent lack of interest in these matters. Comparative cultural studies have depicted Portuguese culture as scoring high on femininity (Hofstede, 1991). «Femininity pertains to societies in which social gender roles overlap» (p. 82) and it may have an influence on people’s attitudes towards ‘the other’ and the role of men and women in the organisation, and in shaping the individual’s behaviour and attitudes towards equality and diversity. On the other hand, Portuguese society likes to portray itself as a homogenous society (Cabral-Cardoso, 2002). Taken together, these factors may partly explain why gender and diversity issues have failed to make it to the top of research agendas in Portuguese academia. The limited number of papers included in this special issue and focusing on the Portuguese context still reflects that state of affairs.