959 resultados para three-level converter


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The Irish economy has grown strongly in recent years. This, combined with other factors in the international trading environment, has sharpened the focus on the need for innovative strategies at a national level which can contribute positively from an enterprise strategy development perspective. As traditional manufacturing activity has migrated to lower labour cost economies questions have been raised concerning the role of supply chain management (SCM) in the evolving Irish business environment. This article describes some of the main drivers in terms of both SCM and the changing economic and business environment. It goes on to propose a three-dimensional approach to understanding the potential role of SCM in the new scenario. This in turn informs the logistics and SCM research agenda from a national policy point of view.

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The Irish economy has grown strongly in recent years. This, combined with other factors in the international trading environment, has sharpened the focus on the need for innovative strategies at a national level which can contribute positively from an enterprise strategy development perspective. As traditional manufacturing activity has migrated to lower labour cost economies questions have been raised concerning the role of supply chain management (SCM) in the evolving Irish business environment. This paper describes some of the main drivers in terms of both SCM and the changing economic and business environment. It goes on to propose a three-dimensional approach to understanding the potential role of SCM in the new scenario. This in turn informs the logistics and SCM research agenda from a national policy point of view.

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Prescribing support tools range from traditional printed texts to state-of-the-art computerised decision support systems. Comparison between available literature is difficult due to country-specific resources often being the focus of the research. In the UK, it is widely accepted that hospitals take their own individualised approaches to reducing prescribing errors. Objective - This study focused on specialist paediatric hospitals. It aimed to identify the localised approaches taken by paediatric hospitals to reduce prescribing errors. Method - Applied thematic analysis was used to explore the publically published board meeting minutes from the four specialist stand-alone paediatric hospitals in England. Three years of data was collected from each hospital. Codes were collected into groups to identify themes from the data. Results - The main themes identified were clinician involvement in prescribing support is important; credit card-sized reminder tools are used to provide prescribing guidance; electronic prescribing is considered important for reducing prescribing errors; feedback from clinical pharmacists on prescribing errors is widely used; junior doctors require extra support when prescribing; medical records may be incomplete and specific prescribing support (eg, antibiotic prescribing support) is widely in use. Conclusions - There is no single collaborative approach taken to paediatric prescribing support in English paediatric hospitals. Success of electronic prescribing in English paediatric hospitals is considerably behind leaders such as the USA. Use of clinical pharmacists to support prescribers is important as supported by previous studies in Spain and the USA.

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This paper details a method of estimating the uncertainty of dimensional measurement for a three-dimensional coordinate measurement machine. An experimental procedure was developed to compare three-dimensional coordinate measurements with calibrated reference points. The reference standard used to calibrate these reference points was a fringe counting interferometer with a multilateration-like technique employed to establish three-dimensional coordinates. This is an extension of the established technique of comparing measured lengths with calibrated lengths. Specifically a distributed coordinate measurement device was tested which consisted of a network of Rotary-Laser Automatic Theodolites (R-LATs), this system is known commercially as indoor GPS (iGPS). The method was found to be practical and was used to estimate that the uncertainty of measurement for the basic iGPS system is approximately 1 mm at a 95% confidence level throughout a measurement volume of approximately 10 m × 10 m × 1.5 m. © 2010 IOP Publishing Ltd.

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2000 Mathematics Subject Classification: 60F05, 60B10.

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The major contribution of the study is the identification of a positive link between perceived effective managerial coaching (PEMC) and team task performance and also, the examination of PEMC adopting a multilevel research design and incorporating dual-source data. Specifically, drawing on social psychology, the thesis aims at developing and testing a comprehensive conceptual framework of the antecedents and consequences of PEMC for knowledge workers. The model takes into consideration intrapersonal, interpersonal and team-level characteristics, which relate to PEMC and, subsequently associate with important work outcomes. In this regard, the thesis identifies PEMC as a practice of dual nature in that it may be experienced not only as a one-on-one workplace developmental interaction, but also as a managerial practice that is experienced by each member of a team for co-ordination purposes. Adopting a cross-sectional survey research design, the hypotheses are tested in three organisations in Greece and the UK. In particular, hierarchical linear modelling of 191 employees nested in 60 teams yields that employees’ learning goal orientation (LGO) and high-quality exchanges between an employee and a manager (LMX) are positively related to effective MC, while a manager’s LGO moderates the relationship between employees’ LGO and PEMC. In turn, PEMC, as a one-on-one practice, is related to cognitive outcomes, such as information sharing, while as a shared team practice is related also to behavioural outcomes, including individual and team performance. Overall, the study contributes to a growing body of coaching and management literature that acknowledges PEMC as a core managerial practice.

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A cascaded DC-DC boost converter is one of the ways to integrate hybrid battery types within a grid-tie inverter. Due to the presence of different battery parameters within the system such as, state-of-charge and/or capacity, a module based distributed power sharing strategy may be used. To implement this sharing strategy, the desired control reference for each module voltage/current control loop needs to be dynamically varied according to these battery parameters. This can cause stability problem within the cascaded converters due to relative battery parameter variations when using the conventional PI control approach. This paper proposes a new control method based on Lyapunov Functions to eliminate this issue. The proposed solution provides a global asymptotic stability at a module level avoiding any instability issue due to parameter variations. A detailed analysis and design of the nonlinear control structure are presented under the distributed sharing control. At last thorough experimental investigations are shown to prove the effectiveness of the proposed control under grid-tie conditions.

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To explore the views of pharmacy and rheumatology stakeholders about system-related barriers to medicines optimisation activities with young people with long-term conditions. A three-phase consensus-building study comprising (1) focus groups with community and hospital pharmacists; (2) semi-structured telephone interviews with lay and professional adolescent rheumatology stakeholders and pharmacy policymakers, and (3) multidisciplinary discussion groups with community and hospital pharmacists and rheumatology staff. Qualitative verbatim transcripts from phases 1 and 2 were subjected to framework analysis. Themes from phase 1 underpinned a briefing for phase 2 interviewees. Themes from phases 1 and 2 generated elements of good pharmacy practice and current/future pharmacy roles for ranking in phase 3. Results from phase 3 prioritisation and ranking exercises were captured on self-completion data collection forms, entered into an Excel spreadsheet and subjected to descriptive statistical analysis. Institutional ethical approval was given by Aston University Health and Life Sciences Research Ethics Committee. Four focus groups were conducted with 18 pharmacists across England, Scotland and Wales (7 hospital, 10 community and 1 community/public health). Fifteen stakeholders took part in telephone interviews (3 pharmacist commissioners; 2 pharmacist policymakers; 2 pharmacy staff members (1 community and 1 hospital); 4 rheumatologists; 1 specialist nurse, and 3 lay juvenile arthritis advocates). Twenty-five participants took part in three discussion groups in adolescent rheumatology centres across England and Scotland (9 community pharmacists; 4 hospital pharmacists; 6 rheumatologists; 5 specialist nurses, and 1 physiotherapist). In all phases of the study, system-level issues were acknowledged as barriers to more engagement with young people and families. Community pharmacists in the focus groups reported that opportunities for engaging with young people were low if parents collected prescriptions alone, which was agreed by other stakeholders. Moreover, institutional/company prescription collection policies – an activity largely disallowed for a young person under 16 without an accompanying parent - were identified by hospital and community pharmacists as barriers to open discussion and engagement. Few community pharmacists reported using Medicines Use Review (England/Wales) or Chronic Medication Service (Scotland) as a medicines optimisation activity with young people; many were unsure about consent procedures. Despite these limitations, rheumatology stakeholders ranked highly the potential of pharmacists empowering young people with general health care skills, such as repeat prescription ordering. The pharmacy profession lacks vision for its role in the care of young people with long-term conditions. Pharmacists and rheumatology stakeholders identified system-level barriers to more engagement with young people who take medicines regularly. We acknowledge that the modest number of participants may have had a specific interest and thus bias for the topic, but this underscores their frank admission of the challenges. Professional guidance and policy, practice frameworks and institutional/company policies must promote flexibility for pharmacy staff to recognise and empower young people who are able to give consent and take responsibility for medicines activities. This will increase mutual confidence and trust, and foster pharmacy’s role in teaching general health care skills. In this way, pharmacists will be able to build long-term relationships with young people and families.

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High-power and high-voltage gain dc-dc converters are key to high-voltage direct current (HVDC) power transmission for offshore wind power. This paper presents an isolated ultra-high step-up dc-dc converter in matrix transformer configuration. A flyback-forward converter is adopted as the power cell and the secondary side matrix connection is introduced to increase the power level and to improve fault tolerance. Because of the modular structure of the converter, the stress on the switching devices is decreased and so is the transformer size. The proposed topology can be operated in column interleaved modes, row interleaved modes, and hybrid working modes in order to deal with the varying energy from the wind farm. Furthermore, fault-tolerant operation is also realized in several fault scenarios. A 400-W dc-dc converter with four cells is developed and experimentally tested to validate the proposed technique, which can be applied to high-power high-voltage dc power transmission.

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Electrolytic capacitors are extensively used in power converters but they are bulky, unreliable, and have short lifetimes. This paper proposes a new capacitor-free high step-up dc-dc converter design for renewable energy applications such as photovoltaics (PVs) and fuel cells. The primary side of the converter includes three interleaved inductors, three main switches, and an active clamp circuit. As a result, the input current ripple is greatly reduced, eliminating the necessity for an input capacitor. In addition, zero voltage switching (ZVS) is achieved during switching transitions for all active switches, so that switching losses can be greatly reduced. Furthermore, a three-phase modular structure and six pulse rectifiers are employed to reduce the output voltage ripple. Since magnetic energy stored in the leakage inductance is recovered, the reverse-recovery issue of the diodes is effectively solved. The proposed converter is justified by simulation and experimental tests on a 1-kW prototype.

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A szerző a Budapesti Corvinus Egyetem Nemzetközi Tanulmányok Intézetének tanársegéde. Tanulmánya a regionalizmus jelenségét vizsgálja Latin-Amerikában, célja az egyes generációk létrejöttének és legfőbb jellemzőinek felvázolása, illetve a jelenleg működő latin-amerikai integrációs tömörülések eredményeinek és legfontosabb kihívásainak vizsgálata. A cikk rávilágít a latin-amerikai alrégiók mentén megalakult csoportok belső integrációja, illetve a más régiókkal való interregionális törekvések közötti szoros összefüggésre, azok kölcsönhatására. A szerző éppen ezért a regionális tömörülések eredményei mellett kitér az egyes latin-amerikai alrégiók más – fejlett és fejlődő világbeli – régiókkal kiépített kapcsolataira is. ______ The paper examines initiatives aimed at regional integration in Latin-America in order to identify the main characteristics of the three generations of regionalism on the continent, as well as show what the main results and challenges are of today's regional organizations. The paper demonstrates that there is an interesting link between the level of integration within the various regional groupings and their interregional contacts with other regions. The author also examines the relations of Latin-American sub-regions with other regions of the world, both developed and developing.

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Oribatid mites are one of the most abundant groups of the ground-dwelling mesofauna. They can be found in almost every terrestrial habitat all over the world and they are characterized by great species richness and great number of individuals. In spite of that not enough is known about their behaviour on community level and their spatial and temporal pattern in different habitats of the world. In our present study the seasonal behaviour of oribatid mite communities was analysed in three types of microhabitats in a temperate deciduous forest: in leaf litter, soil and moss. Samples were collected at a given site in a year and a half and the oribatid mite communities living there were studied on genus level along with the changes of meteorological factors characteristic of the area. The results show that corresponding to similar previous researches, the communities in our study do not have a seasonally changing, returning pattern either. Based on this, we can conclude that climatic differences and differences in other seasonally changing factors between the seasons do not have a significant role in the annual change of communities. Besides that we discovered that the communities of the three microhabitats are not completely the same. It is the oribatid mite community of the moss which differs mostly from communities in the leaf litter and in the soil. Our study calls attention among others to the fact that compositional changes of the oribatid mite communities living all over the world and their causes are unclear to date.

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The purpose of this study was to examine the relationship between the spiritual well-being of nurses and its influence on their attitudes toward providing spiritual care to patients. Two research instruments and a demographic data form were used for the survey. Using a descriptive design, tbe Spiritual Well-Being Scale, the Health Professional's Spiritual Role Scale, and the demographic data form were administered to 100 registered nurses from a large South Florida teaching hospital. The findings indicated a significantly positive correlation between the overall Spiritual Well-Being Scale and the Health Professional's Spiritual Role Scale (r = 0.52; p =.005). Significant differences were found between correlation of nurses' levels of spiritual well-being and all sociodemographic factors except for the three Age Groups and for religious affiliations. Findings have implications for how nurses should be trained in meeting patients total needs. ^

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A review of the literature reveals few research has attempted to demonstrate if a relationship exists between the type of teacher training a science teacher has received and the perceived attitudes of his/her students. Some of the teacher preparation factors examined in this study include the college major chosen by the science teacher, the highest degree earned, the number of years of teaching experience, the type of science course taught, and the grade level taught by the teacher. This study examined how the various factors mentioned, could influence the behaviors which are characteristic of the teacher, and how these behaviors could be reflective in the classroom environment experienced by the students.^ The instrument used in the study was the Classroom Environment Scale (CES), Real Form. The measured classroom environment was broken down into three separate dimensions, with three components within each dimension in the CES. Multiple Regression statistical analyses examined how components of the teachers' education influenced the perceived dimensions of the classroom environment from the students.^ The study occurred in Miami-Dade County Florida, with a predominantly urban high school student population. There were 40 secondary science teachers involved, each with an average of 30 students. The total number of students sampled in the study was 1200. The teachers who participated in the study taught the entire range of secondary science courses offered at this large school district. All teachers were selected by the researcher so that a balance would occur in the sample between teachers who were education major versus science major. Additionally, the researcher selected teachers so that a balance occurred in regards to the different levels of college degrees earned among those involved in the study.^ Several research questions sought to determine if there was significant difference between the type of the educational background obtained by secondary science teachers and the students' perception of the classroom environment. Other research questions sought to determine if there were significant differences in the students' perceptions of the classroom environment for secondary science teachers who taught biological content, or non-biological content sciences. An additional research question sought to evaluate if the grade level taught would affect the students' perception of the classroom environment. (Abstract shortened by UMI.) ^

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This dissertation describes the findings and implications of a correlational analysis. Scores earned on the Computerized Placement Test (CPT), sentence skills, were compared to essay scores of advanced English as a Second Language (ESL) students. As the CPT is designed for native speakers of English, it was hypothesized that it could be an invalid or unreliable instrument for non-native speakers. Florida community college students are mandated to take the CPT to determine preparedness, as are students at many other U.S. and Canadian colleges. If incoming students score low on the CPT, they may be required to take up to three semesters of remedial coursework. It is essential that scores earned by non-native speakers of English accurately reflect their ability level. They constitute a large and growing body of non-traditional students enrolled at community colleges.^ The study was conducted at Miami-Dade Community College, Wolfson Campus, fall 1997. Participants included 106 advanced ESL students who took both the CPT sentence skills test and wrote final essay exams. The essay exams were holistically scored by trained readers. Also, the participants took the Placement Articulation Software Service (PASS) exam, an alternative form of the CPT. Scores on the CPT and essays were compared by means of a Pearson product-moment correlation to validate the CPT. Scores on the CPT and the PASS exam were compared in the same manner to verify reliability. A percentage of appropriate placements was determined by comparing essay scores to CPT cutoff score ranges. Finally, the instruments were evaluated by means of independent-samples t-tests for performance differences between gender, age, and first language groups.^ The results indicate that the CPT sentence skills test is a valid and reliable placement instrument for advanced- level ESL students who intend to pursue community college degrees. The correlations demonstrated a substantial relationship between CPT and essay scores and a marked relationship between CPT and PASS scores. Appropriate placements were made in 86% of the cases. Furthermore, the CPT was found to discriminate equally among the gender, age, and first language groups included in this study. ^