Operation of synchronous machines in the power range of several 10 MW with variable speed up to 7,000 rpm using a current converter is, thanks to the development of power…
Abstract
Purpose
Operation of synchronous machines in the power range of several 10 MW with variable speed up to 7,000 rpm using a current converter is, thanks to the development of power switches, possible and economically reasonable today. However, current harmonics, produced by converter, generate additional losses, especially eddy current losses on the rotor surface are produced by the converter, which strongly depend on the rotor permeability. The purpose of this paper is to show that an accurate machine modeling is required, in order to consider the nonlinearity of electromagnetic processes inside.
Design/methodology/approach
This paper concentrates on the determination of the rotor surface losses in a three‐phase turbogenerator feeding a current converter. Saturation of rotor steel is taken into account using a transient finite element method model of the machine, coupled with a converter model.
Findings
A detailed analysis of the damper currents and losses in a turbogenerator operating with a frequency converter is presented. The effectivenes of damper winding modifications, concerning the eddy current loss reduction in the rotor surface, is depicted.
Practical implications
The introduced modelling technique presents an accurate electromagnetic modelling of an I‐converter‐fed synchronous generator with massiv poles, which is fed by a current converter and so has to sustain additional eddy current losses in the rotor surface. In this way, the amount and distribution of these losses are evaluated more accurately which allows a more efficient design of the damper winding as well as machine cooling system.
Originality/value
Some researchers have made contributions to the analysis of current converter‐fed synchronous machine, regarding terminal behaviour of the machine. This paper focuses on eddy current losses on the rotor surface, considering the time and space dependent saturation aspect in the machine, particularly in the rotor.
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Nobody concerned with political economy can neglect the history of economic doctrines. Structural changes in the economy and society influence economic thinking and, conversely…
Abstract
Nobody concerned with political economy can neglect the history of economic doctrines. Structural changes in the economy and society influence economic thinking and, conversely, innovative thought structures and attitudes have almost always forced economic institutions and modes of behaviour to adjust. We learn from the history of economic doctrines how a particular theory emerged and whether, and in which environment, it could take root. We can see how a school evolves out of a common methodological perception and similar techniques of analysis, and how it has to establish itself. The interaction between unresolved problems on the one hand, and the search for better solutions or explanations on the other, leads to a change in paradigma and to the formation of new lines of reasoning. As long as the real world is subject to progress and change scientific search for explanation must out of necessity continue.
Timothy C. Weiskel and Richard A. Gray
Current news on environmental problems frequently emphasizes the totally unprecedented nature of the ecological crises that beset us in this nation and the Western world as a…
Abstract
Current news on environmental problems frequently emphasizes the totally unprecedented nature of the ecological crises that beset us in this nation and the Western world as a whole. We are told, for example, that the summer of 1988 constituted “the hottest summer on record” in North America. Similarly we hear mat Boston Harbor has never in its history been so polluted, and in European waters seal populations died of an epidemic in 1988 on a scale never before witnessed by man. By stressing this “never before” aspect of events, it is sometimes argued mat the experience of the past is largely irrelevant for policy planners. Since our circumstances are new, so the argument runs, past experience leaves us with little or no instruction for the formulation of a practical public policy for the environment.
Discusses collection building of contemporary German belles‐lettres and introduces 20 contemporary German‐language writers of the younger generation, presenting their…
Abstract
Discusses collection building of contemporary German belles‐lettres and introduces 20 contemporary German‐language writers of the younger generation, presenting their bio‐bibliographies. Librarians who are not already collecting these authors might consider expanding their German literature collections by adding some of the works listed.
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This chapter examines the economics of alternative healing in Brazil.
Abstract
Purpose
This chapter examines the economics of alternative healing in Brazil.
Methodology/approach
Two narratives are selected from extensive observations and interviews over a period of years. The presentation chronicles the accounts of people experiencing physical symptoms who sought further advice from friends and relatives after visits to conventional medical providers failed to cure them.
Findings
In response to a recommendation from one of those consulted, one person went to a spirit “received” by a Kardecist/Spiritist healer-medium while the other obtained treatment from an otherworldly being at an Umbanda center. The respective “therapeutic” procedures are described and analyzed in terms of the beliefs and the worldviews of each of the traditions. If satisfied with the outcome, the patient fulfills an implicit bargain with the otherworldly being(s) and its religious group by adopting their beliefs and practices. This conversion is “payment” for the healing services rendered.
Social implications
Since some treatments are successful and others are not, the implications of this exchange is that many Brazilians may change their religions several times during their lifespan. As a result of this behavior individuals circulate among the several religious groups that are always in competition with each other.
Originality/value
The analysis provides a distinctive insight into, and original way to understand, alternative health care in Brazil.
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Thea Williamson and Aris Clemons
Little research has been done exploring the nature of multilingual students who are not categorized as English language learners (ELLs) in English language arts (ELA) classes…
Abstract
Purpose
Little research has been done exploring the nature of multilingual students who are not categorized as English language learners (ELLs) in English language arts (ELA) classes. This study about a group of multilingual girls in an ELA class led by a monolingual white teacher aims to show how, when a teacher makes space for translanguaging practices in ELA, multilingual students disrupt norms of English only.
Design/methodology/approach
The authors use reconstructive discourse analysis to understand translanguaging across a variety of linguistic productions for a group of four focal students. Data sources include fieldnotes from 29 classroom observations, writing samples and process documents and 8.5 h of recorded classroom discourse.
Findings
Students used multilingualism across a variety of discourse modes, frequently in spoken language and rarely in written work. Translanguaging was most present in small-group peer talk structures, where students did relationship building, generated ideas for writing and managed their writing agendas, including feelings about writing. In addition, Spanish served as “elevated vocabulary” in writing. Across discourse modes, translanguaging served to develop academic proficiency in writing.
Originality/value
The authors proposed a more expansive approach to data analysis in English-mostly cases – i.e. environments shaped by multilingual students in monolingual school contexts – to argue for anti-deficit approaches to literacy development for multilingual students. Analyzing classroom talk alongside literacy allows for a more nuanced understanding of translanguaging practices in academic writing. They also show how even monolingual teachers can disrupt monolingual hegemony in ELA classrooms with high populations of multilingual students.
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Although employee helping behaviors have been widely examined by organizational and human resource management scholars, relatively little is known about the antecedents and…
Abstract
Although employee helping behaviors have been widely examined by organizational and human resource management scholars, relatively little is known about the antecedents and consequences of help-seeking in the workplace. Seeking to fill this gap, I draw from the social and counseling psychology literatures, as well as from research in epidemiology and health sociology to first conceptualize the notion of employee help-seeking and then to identify the variables and mechanisms potentially driving such behavior in work organizations. My critical review of this literature suggests that the application of existing models of help-seeking may offer limited predictive utility when applied to the workplace unless help-seeking is conceived as the outcome of a multi-level process. That in mind, I propose a model of employee help-seeking that takes into account the potential direct and cross-level moderating effects of a variety of situational factors (e.g., the nature of the particular problem, organizational norms, support climate) that might have differential influences on help-seeking behavior depending on the particular phase of the help-seeking process examined. Following this, I focus on two sets of help-seeking outcomes, namely, the implications of employee help-seeking on individual and group performance, and the impact of help-seeking on employee well-being. The chapter concludes with a brief examination of some of the more critical issues in employee help-seeking that remain to be explored (e.g., the timing of help solicitation) as well as the methodological challenges likely to be faced by those seeking to engage in such exploration.
This chapter provides an introduction to the world of family companies and family constitutions from a legal perspective. It first studies the legal types of business…
Abstract
This chapter provides an introduction to the world of family companies and family constitutions from a legal perspective. It first studies the legal types of business organizations that family firms have chosen across time and jurisdictions. It then illustrates how early predecessors of family constitutions evolved in the late Middle Ages and what modern family constitutions look like in different countries today. Further considerations are devoted to the governance framework of family firms. The chapter concludes by exploring the potential legal effects of family constitutions under German company and contract law.
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The purpose of this paper is to examine the main contract principles which govern the international arbitration contract with special emphasis to examine contract principle found…
Abstract
Purpose
The purpose of this paper is to examine the main contract principles which govern the international arbitration contract with special emphasis to examine contract principle found of the Middle East, how international principles of contract are perceived in the region, and whether there are any dominant contract principles.
Design/methodology/approach
A general exploratory research procedure used to give a better grasp of various aspects of socio‐legal approaches. The paper seeks to create knowledge that can be used to retrieve some pressing social and organisational understanding in the said region. The first part of the paper examines the role of ethics and tradition in understanding Middle Eastern contract principles. The second part examines the impact of Islamic Law on commercial contract principles. The third section analyses the regional perception of international contract principles. Finally, the paper addresses some contemporary issues of international contracts in the Middle East.
Findings
The paper showed that the legal perceptions of international contract principles reflect regional legal thinking which has been influenced by a mixed understanding of regional traditions, Islamic contract law principles as well as Western contract principles when these principles match regional legal culture. Overall, it showed that still under such mixed understanding, there are strong regional legal traditions and these are found in Islamic contract principles and affects commercial contract experiences. In general, a significant difference still exists between modern international contract principles and those in the Middle East.
Practical implications
The paper generates a knowledge that mixed understanding in regard to international contract arbitration principles due historical and cultural reasoning. Arab States does not share common understanding of international contract principles. Thus, it is very superfluous to propose the argument that there is sole Middle Eastern regional perception which dominates every Arab State. Therefore, special understandings and considerations should be given to every international arbitration contract from certain Arab State entity to another.
Originality/value
The paper provides a clear understanding of the guidelines for international commercial arbitration contract in the Middle East. Legal culture should be taken into consideration if a successful contract implementation has to be achieved.
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There is currently a lack of research describing the best way to design learning environments for increasing numbers of children with autism. The purpose of this study was to…
Abstract
Purpose
There is currently a lack of research describing the best way to design learning environments for increasing numbers of children with autism. The purpose of this study was to determine the impact of classroom design on the learning and behaviour of pupils with severe autism. The research variables of interest were classroom layout; furniture, fittings and equipment (FFE); materials; colour scheme; wayfinding; lighting; acoustics; and security.
Design/methodology/approach
This study conducted a post-occupancy evaluation of classrooms for pupils with severe autism aged 3–19 in a school ten years after its completion. Data collection included a visual assessment of the building and an online survey to educators and administrators asking how satisfied they were that the research variables benefited pupils with severe autism.
Findings
Key findings were that zoned areas for different activities met students’ needs. Withdrawal rooms off the classroom, access to shared hygiene facilities and a secure outdoor area received high ratings. The main criticisms were the lack of robustness of FFE and the inability to control temperature. Results were collated into a table of recommendations for classroom design for severely autistic pupils.
Originality/value
The findings demonstrate classroom features that support the needs of pupils with severe autism, an area with limited prior research. Some findings support previous research and some adds new knowledge to our understanding of design for this population. The results provide empirical evidence for professionals involved in designing classrooms for pupils with severe autism.