908 resultados para Multilevel inverter
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This study investigated within-person relationships between daily problem solving demands, selection, optimization, and compensation (SOC) strategy use, job satisfaction, and fatigue at work. Based on conservation of resources theory, it was hypothesized that high SOC strategy use boosts the positive relationship between problem solving demands and job satisfaction, and buffers the positive relationship between problem solving demands and fatigue. Using a daily diary study design, data were collected from 64 administrative employees who completed a general questionnaire and two daily online questionnaires over four work days. Multilevel analyses showed that problem solving demands were positively related to fatigue, but unrelated to job satisfaction. SOC strategy use was positively related to job satisfaction, but unrelated to fatigue. A buffering effect of high SOC strategy use on the demands-fatigue relationship was found, but no booster effect on the demands-satisfaction relationship. The results suggest that high SOC strategy use is a resource that protects employees from the negative effects of high problem solving demands.
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Ones and Dilchert (2012) highlight the importance of examining workplace environmental sustainability at the interindividual (or between-person) and organizational levels. In this commentary, we aim to extend these authors’ framework by focusing on pro-environmental behaviors and their potential predictors at the intraindividual, or within-person, level. To this end, we will first describe the intraindividual perspective, its benefits, and the diary study methodology often used to operationalize this perspective. Secondly, we will share how the intraindividual perspective was useful in an empirical study we conducted on multilevel relationships among employees’ pro-environmental attitude, daily affect, and daily proenvironmental behaviors. Finally, we will discuss a number of possible limitations of the diary study methodology, ways to Correspondence concerning this article should be addressed to Megan J. Bissing-Olson. E-mail: m.bissing-olson@uq.edu.au Address: School of Psychology, The University of Queensland, Brisbane, Queensland 4072, Australia overcome them, and directions for future research.
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According to career construction theory, continuous adaptation to the work environment is crucial to achieve work and career success. In this study, we examined the relative importance of career adaptability for job performance ratings using an experimental policy-capturing design. Employees (N = 135) from different vocational backgrounds rated the overall job performance of fictitious employees in 40 scenarios based on information about their career adaptability, mental ability, conscientiousness, and job complexity. We used multilevel modeling to investigate the relative importance of each factor. Consistent with expectations, career adaptability positively predicted job performance ratings, and this effect was relatively smaller than the effects of conscientiousness and mental ability. Job complexity did not moderate the effect of career adaptability on job performance ratings, suggesting that career adaptability predicts job performance ratings in high-, medium-, and low-complexity jobs. Consistent with previous research, the effect of mental ability on job performance ratings was stronger in high- compared to low-complexity jobs. Overall, our findings provide initial evidence for the predictive validity of employees' career adaptability with regard to other people's ratings of job performance.
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Organizational researchers and practitioners are increasingly interested in self-regulatory strategies employees can use at work to sustain or improve their occupational well-being. A recent cross-sectional study on energy management strategies suggested that many work-related strategies (e.g., setting a new goal) are positively related to occupational well-being, whereas many micro-breaks (e.g., listening to music) are negatively related to occupational well-being. We used a diary study design to take a closer look at the effects of these energy management strategies on fatigue and vitality. Based on conservation of resources theory, we hypothesized that both types of energy management strategies negatively predict fatigue and positively predict vitality. Employees (N = 124) responded to a baseline survey and to hourly surveys across one work day (6.7 times on average). Consistent with previous research, between-person differences in the use of work-related strategies were positively associated with between-person differences in vitality. However, results of multilevel analyses of the hourly diary data showed that only micro-breaks negatively predicted fatigue and positively predicted vitality. These findings suggest that taking micro-breaks during the work day may have short-term effects on occupational well-being, whereas using work-related strategies may have long-term effects.
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An alternative approach to digital PWM generation uses an accumulator rather than a counter to generate the carrier. This offers several advantages. The resolution and gain of the pulse width modulator remain constant regardless of the module clock frequency and PWM output frequency. The PWM resolution also becomes fixed at the register width. Even at high PWM frequencies, the resolution remains high when averaged over a number of PWM cycles. An inherent dithering of the PWM waveform introduced over successive cycles blurs the switching spectra without distorting the modulating waveform. The technique also lends itself to easily generating several phase shifted PWM waveforms suitable for multilevel converter modulation. Several example waveforms generated using both simulation and FPGA hardware are presented.
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- Purpose This study aims to investigate the extent to which employee outcomes (anxiety/depression, bullying and workers’ compensation claims thoughts) are affected by shared perceptions of supervisor conflict management style (CMS). Further, this study aims to assess cross-level moderating effects of supervisor CMS climate on the positive association between relationship conflict and these outcomes. - Design/methodology/approach Multilevel modeling was conducted using a sample of 401 employees nested in 69 workgroups. - Findings High collaborating, low yielding and low forcing climates (positive supervisor climates) were associated with lower anxiety/depression, bullying and claim thoughts. Unexpectedly, the direction of moderation showed that the positive association between relationship conflict and anxiety/depression and bullying was stronger for positive supervisor CMS climates than for negative supervisor CMS climates (low collaborating, high yielding and high forcing). Nevertheless, these interactions revealed that positive supervisor climates were the most effective at reducing anxiety/depression and bullying when relationship conflict was low. For claim thoughts, positive supervisor CMS climates had the predicted stress-buffering effects. - Research limitations/implications Employees benefit from supervisors creating positive CMS climates when dealing with conflict as a third party, and intervening when conflict is low, when their intervention is more likely to minimize anxiety/depression and bullying. - Originality/value By considering the unique perspective of employees’ shared perceptions of supervisor CMS, important implications for the span of influence of supervisor behavior on employee well-being have been indicated.
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The recent trend towards minimizing the interconnections in large scale integration (LSI) circuits has led to intensive investigation in the development of ternary circuits and the improvement of their design. The ternary multiplexer is a convenient and useful logic module which can be used as a basic building block in the design of a ternary system. This paper discusses a systematic procedure for the simplification and realization of ternary functions using ternary multiplexers as building blocks. Both single level and multilevel multiplexing techniques are considered. The importance of the design procedure is highlighted by considering two specific applications, namely, the development of ternary adder/subtractor and TCD to ternary converter.
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Much of physical education curriculum in the developed world and specifically in Australia tends to be guided in principle by syllabus documents that represent, in varying degrees, some form of government education priorities. Through the use of critical discourse analysis we analyze one such syllabus example (an official syllabus document of one of the Australian States) to explore the relationships between the emancipatory/social justice expectations presented in the rubric of and introduction to the official syllabus document, and the language details of learning outcomes that indicate how the expectations might be satisfied. Given the complexity and multilevel pathways of message systems/ideologies we question the efficacy of such documents oriented around social justice principles to genuinely deliver more radical agendas which promote social change and encourage a preparedness to engage in social action leading to a betterment of society.
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Speed control of ac motors requires variable frequency, variable current, or variable voltage supply. Variable frequency supply can be obtained directly from a fixed frequency supply by using a frequency converter or from a dc source using inverters. In this paper a control technique for reference wave adaptive-current generation by modulating the inverter voltage is explained. Extension of this technique for three-phase induction-motor speed control is briefly explained. The oscillograms of the current waveforms obtained from the experimental setup are also shown.
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An isolated wind power generation scheme using slip ring induction machine (SRIM) is proposed. The proposed scheme maintains constant load voltage and frequency irrespective of the wind speed or load variation. The power circuit consists of two back-to-back connected inverters with a common dc link, where one inverter is directly connected to the rotor side of SRIM and the other inverter is connected to the stator side of the SRIM through LC filter. Developing a negative sequence compensation method to ensure that, even under the presence of unbalanced load, the generator experiences almost balanced three-phase current and most of the unbalanced current is directed through the stator side converter is the focus here. The SRIM controller varies the speed of the generator with variation in the wind speed to extract maximum power. The difference of the generated power and the load power is either stored in or extracted from a battery bank, which is interfaced to the common dc link through a multiphase bidirectional fly-back dc-dc converter. The SRIM control scheme, maximum power point extraction algorithm and the fly-back converter topology are incorporated from available literature. The proposed scheme is both simulated and experimentally verified.
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Transforming growth factor β signalling through Smad3 in allergy Allergic diseases, such as atopic dermatitis, asthma, and contact dermatitis are complex diseases influenced by both genetic and environmental factors. It is still unclear why allergy and subsequent allergic disease occur in some individuals but not in others. Transforming growth factor (TGF)-β is an important immunomodulatory and fibrogenic factor that regulates cellular processes in injured and inflamed skin. TGF-β has a significant role in the regulation of the allergen-induced immune response participating in the development of allergic and asthmatic inflammation. TGF-β is known to be an immunomodulatory factor in the progression of delayed type hypersensitivity reactions and allergic contact dermatitis. TGF-β is crucial in regulating the cellular responses involved in allergy, such as differentiation, proliferation and migration. TGF-β signals are delivered from the cytoplasm to the nucleus by TGF-β signal transducers called Smads. Smad3 is a major signal transducer in TGF-β -signalling that controls the expression of target genes in the nucleus in a cell-type specific manner. The role of TGF-β-Smad3 -signalling in the immunoregulation and pathophysiology of allergic disorders is still poorly understood. In this thesis, the role of TGF-β-Smad -signalling pathway using Smad3 -deficient knock out mice in the murine models of allergic diseases; atopic dermatitis, asthma and allergic contact reactions, was examined. Smad3-pathway regulates allergen induced skin inflammation and systemic IgE antibody production in a murine model atopic dermatitis. The defect in Smad3 -signalling decreased Th2 cytokine (IL-13 and IL-5) mRNA expression in the lung, modulated allergen induced specific IgG1 response, and affected mucus production in the lung in a murine model of asthma. TGF-β / Smad3 -signalling contributed to inflammatory hypersensitivity reactions and disease progression via modulation of chemokine and cytokine expression and inflammatory cell recruitment, cell proliferation and regulation of the specific antibody response in a murine model of contact hypersensitivity. TGF-β modulates inflammatory responses - at least partly through the Smad3 pathway - but also through other compensatory, non-Smad-dependent pathways. Understanding the effects of the TGF-β signalling pathway in the immune system and in disease models can help in elucidating the multilevel effects of TGF-β. Unravelling the mechanisms of Smad3 may open new possibilities for treating and preventing allergic responses, which may lead to severe illness and loss of work ability. In the future the Smad3 signalling pathway might be a potential target in the therapy of allergic diseases.
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Despite an increased risk of mental health problems in adolescents with Autism Spectrum Disorder (ASD), there is limited research on effective prevention approaches for this population. Funded by the Cooperative Research Centre for Living with Autism, a theoretically and empirically supported school-based preventative model has been developed to alter the negative trajectory and promote wellbeing and positive mental health in adolescents with ASD. This conceptual paper provides the rationale, theoretical, empirical and methodological framework of a multilayered intervention targeting the school, parents, and adolescents on the spectrum. Two important interrelated protective factors have been identified in community adolescent samples, namely the sense of belonging (connectedness) to school, and the capacity for self and affect regulation in the face of stress (i.e., resilience). We describe how a confluence of theories from social psychology, developmental psychology and family systems theory, along with empirical evidence (including emerging neurobiological evidence) supports the interrelationships between these protective factors and many indices of wellbeing. However, the characteristics of ASD (including social and communication difficulties, and frequently difficulties with changes and transitions, and diminished optimism and self-esteem) impair access to these vital protective factors. The paper describes how evidenced-based interventions at the school level for promoting inclusive schools (using the Index for Inclusion), and interventions for adolescents and parents to promote resilience and belonging (using the Resourceful Adolescent Program (RAP)), are adapted and integrated for adolescents with ASD. This multisite proof of concept study will confirm whether this multilevel school-based intervention is promising, feasible and sustainable.
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In this paper, the effects of energy quantization on different single-electron transistor (SET) circuits (logic inverter, current-biased circuits, and hybrid MOS-SET circuits) are analyzed through analytical modeling and Monte Carlo simulations. It is shown that energy quantizationmainly increases the Coulomb blockade area and Coulomb blockade oscillation periodicity, and thus, affects the SET circuit performance. A new model for the noise margin of the SET inverter is proposed, which includes the energy quantization effects. Using the noise margin as a metric, the robustness of the SET inverter is studied against the effects of energy quantization. An analytical expression is developed, which explicitly defines the maximum energy quantization (termed as ``quantization threshold'') that an SET inverter can withstand before its noise margin falls below a specified tolerance level. The effects of energy quantization are further studiedfor the current-biased negative differential resistance (NDR) circuitand hybrid SETMOS circuit. A new model for the conductance of NDR characteristics is also formulated that explains the energy quantization effects.
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Novel switching sequences can be employed in spacevector-based pulsewidth modulation (PWM) of voltage source inverters. Differentswitching sequences are evaluated and compared in terms of inverter switching loss. A hybrid PWM technique named minimum switching loss PWM is proposed, which reduces the inverter switching loss compared to conventional space vector PWM (CSVPWM) and discontinuous PWM techniques at a given average switching frequency. Further, four space-vector-based hybrid PWM techniques are proposed that reduce line current distortion as well as switching loss in motor drives, compared to CSVPWM. Theoretical and experimental results are presented.
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A voltage source inverter-fed induction motor produces a pulsating torque due to application of nonsinusoidal voltages. Torque pulsation is strongly influenced by the pulsewidth modulation (PWM) method employed. Conventional space vector PWM (CSVPWM) is known to result in less torque ripple than sine-triangle PWM. This paper aims at further reduction in the pulsating torque by employing advanced bus-clamping switching sequences, which apply an active vector twice in a subcycle. This paper proposes a hybrid PWM technique which employs such advanced bus-clamping sequences in conjunction with a conventional switching sequence. The proposed hybrid PWM technique is shown to reduce the torque ripple considerably over CSVPWM along with a marginal reduction in current ripple.