926 resultados para Active and Reactive Power


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The majority of women's health nurses in this study work in generalist community health centres. They have developed their praxis within the philosophy and policies of the broader women's health movement and primary health care principles in Australia. The fundamental assumption underlying this study is that women's health nurses possess a unique body of knowledge and clinical wisdom that has not been previously documented and explored. The epistemological base from which these nurses' operate offers important insights into the substantive issues that create and continually shape the practice world of nurses and their clients. Whether this represents a (re)construction of the dominant forms of health care service delivery for women is examined in this study. The study specifically aims at exploring the practice issues and experience of women's health service provision by women's health nurses in the context of the provision of cervical cancer screening services. In mapping this particular group of nurses practice, it sets out to examine the professional and theoretical issues in contemporary nursing and women's health care. In critically analysing the powerful discourses that shape and reshape nursing work, the study raises the concern that previous analyses of pursing work tend to universalise the structural and social subordination of nurses and nursing knowledge. This universalism is most often based on examples of midwifery and nursing work in hospital settings, and subsequently, because of these conceptualisations, all of nursing is too often deemed as a dependent occupation, with little agency, and is analysed as always in relation to medicine, to hospitals, to other knowledge forms. Denoting certain discourses as dominant proposes a relationship of power and knowledge and the thesis argues that all work relations and practices in health are structured by certain power/knowledge relations. This analysis reveals that there IX are many competing and complimentary power/knowledge relations that structure nursing, but that nursing, and in particular women's health nurses, also challenge the power/knowledge relations around them. Through examining theories of power and knowledge the analysis, argues that theoretical eclecticism is necessary to address the complex and varied nature of nursing work. In particular it identifies that postmodern and radical feminist theorising provide the most appropriate framework to further analyse and interpret the work of women's health nurses. Fundamental to the position argued in this thesis is a feminist perspective. This position creates important theoretical and methodological links throughout the whole study. Feminist methodology was employed to guide the design, the collection and the analysis. Intrinsic to this process was the use of the 'voices' of women's health nurses as the basis for theorising. The 'voices' of these nurses are highlighted in the chapters as italicised bold script. A constant companion along the way in examining women's health nurses' work, was the reflexivity with feminist research processes, the theoretical discussions and their 'voices'. Capturing and analysing descriptive accounts of nursing praxis is seen in this thesis as providing a way to theorise about nursing work. This methodology is able to demonstrate the knowledge forms embedded in clinical nursing praxis. Three conceptual threads emerge throughout the discussions: one focuses on nursing praxis as a distinct process, with its own distinct epistemological base rather than in relation to 'other' knowledge forms; another describes the medical restriction and opposition as experienced by this group of nurses, but also of their resistance to medical opposition. The third theme apparent from the interviews, and which was conceptualised as beyond resistance, was the description of the alternative discourses evident in nursing work, and this focused on notions of being a professional and on autonomous nursing praxis. This study concludes that rather than accepting the totalising discourses about nursing there are examples within nursing of resistance—both ideologically and X in practice—to these dominant discourses. Women's health nurses represent an important model of women's health service delivery, an analysis of which can contribute to critically reflecting on the 'paradigm of oppression' cited in nursing and about nursing more generally. Reflecting on women's health service delivery also has relevance in today's policy environment, where structural shifts in Commonwealth/State funding arrangements in community based care, may undermine women's health programs. In summary this study identifies three important propositions for nursing: • nursing praxis can reconstruct traditional models of health care; • nursing praxis is powerful and able to 'resist' dominant discourses; and • nursing praxis can be transformative. Joining feminist perspectives and alternative analyses of power provides a pluralistic and emancipatory politics for viewing, describing and analysing 'other' nursing work. At the micro sites of power and knowledge relations—in the everyday practice worlds of nurses, of negotiation and renegotiation, of work on the margins and at the centre—women's health nurses' praxis operates as a positive, productive and reconstructive force in health care.

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Case study research investigating the impact of culture upon a Hong Kong based construction contractor's leadership in implementing an Enterprise Resource Planning (ERP) system unearthed rich data relating to the predominantly Hong Kong Chinese cultural perspective of power, leadership and followership. Intimately involved participants were surveyed using both structured and semi-structured interviews. The study's focus was centred upon the interplay between culture, power and how people interact with the way that the ERP is used and how teams of people involved in the ERP implementation, perceived the supportive nature of the organisation's leadership in deploying the ERP. A culturally sensitive empowering leadership style was a significant issue in successfully project managing and deploying the ERP. Understanding how teams and their leaders interact and how power and trust influences the facilitation role of leadership is also useful in gauging how an ERP can be most effectively deployed.

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This paper reports a case study of a workplace health programme in an international information technology company. Discourse analysis was used to identify how specific forms of knowledge create understandings of health and influence power relations between employee and organization. These forms of knowledge are shown to make employee health both visible and invisible in particular ways. Workplace health discourse encourages the employee to take responsibility for self-assessment and behaviour adjustment to become healthier employees. This is shown to be an ethical project which results in the alignment of personal and corporate goals.

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In this article, we compare the small sample size and power properties of a newly developed endogenous structural break unit root test of Narayan and Popp (NP, 2010) with the existing two break unit root tests, namely the Lumsdaine and Papell (LP, 1997) and the Lee and Strazicich (LS, 2003) tests. In contrast to the widely used LP and LS tests, the NP test chooses the break date by maximizing the significance of the break dummy coefficient. Using Monte Carlo simulations, we show that the NP test has better size and high power, and identifies the structural breaks accurately. Power and size comparisons of the NP test with the LP and LS tests reveal that the NP test is significantly superior.

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This paper presents an analysis of optimum rectifier circuits for wireless energy harvesting in deep brain stimulation (DBS) devices. Since DBS demands compact and low power consumption devices, small, high conversion efficient, and high output voltage rectifiers need to be developed. The investigation that is presented in this paper is analytical and simulated based. Analysis on a variety of circuit configurations brings more evidence to improve the performance of rectifiers. Analytical parameters influencing the output DC voltage and the efficiency of the rectifiers are described. The operating frequency of the 915 MHz industrial, scientific and medical (ISM) radio band is used in this study. The maximum conversion efficiency of the LC matched half wave rectifier, the Greinacher voltage doubler, the Delon doubler, and the 2-stage voltage multiplier is obtained as 56.34%, 74.45%, 71.48%, and 31.44%, respectively, at the 30 dBm input power level. The corresponding maximum output DC voltages are 6.27 V, 16.83 V, 13.36 V, and 9.20 V. Thus the Greinacher voltage doubler is deemed as the best configuration according to the conversion efficiency and the output voltage measurements.

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Maintaining reliability and stability of a power systems in transmission and distribution level becomes a big challenge in present scenario. Grid operators are always responsible to maintain equilibrium between available power generation and demand of end users. Maintaining grid balance is a bigger issue, in case of any unexpected generation shortage or grid disturbance or integration of any renewable energy sources like wind and solar power in the energy mix. In order to compensate such imbalance and to facilitate more renewable energy sources with the grid, energy storage system (ESS) started to be playing an important role with the advancement of the state of the art technology. ESS can also help to get reduction in greenhouse gas (GHG) emission by means of integrating more renewable energy sources to the grid. There are various types of Energy Storage (ES) technologies which are being used in power systems network from large scale (above 50MW) to small scale (up to 100KW). Based on the characteristics, each storage technology has their own merits and demerits. This paper carried out extensive review study and verifies merits and demerits of each storage technology and identifies the suitable technology for the future. This paper also has conducted feasibility study with the aid of E-SelectTM tool for various ES technologies in applications point of view at different grid locations. This review study helps to evaluate feasible ES technology for a particular electrical application and also helps to develop smart hybrid storage system for grid applications in efficient way.

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Increased concern about global warming coupled with the escalating demand of energy has driven the conventional power system to be more reliable one by integrating Renewable Energies (RE) in to grid. Over the recent years, integration of solar PV forming a gridconnected PV is considered as one of the most promisingtechnologies to the developed countries like Australia to meet the growing demand of energy. This rapid increase in grid connected photovoltaic (PV) systems has made the supply utilities concerned about the drastic effects that have to be considered on the distribution network in particular voltage fluctuations, harmonic distortions and the Power factor for sustainable power generation. However, irrespective of thefact that the utility grid can accommodate the variability of load or irregular solar irradiance, it is essential to study the impact of grid connected PV systems during higher penetration levels as the intermittent nature of solar PV adversely effects the grid characteristics in meeting the load demand. Hence, keeping this in track, this paper examines the grid-connected PV system considering a residential network of Geelong region (38◦.09' S and 144◦.21’ E) and explores the level of impacts considering summer load profile with a change in the level of integrations. Initially, a PV power system network model is developed in Matlab-Simulink environment and the simulations are carried out to explore the impacts of solar PV penetration at low voltage distribution network considering power quality (PQ) issues such as voltage fluctuations, harmonics distortion at different load conditions.

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Public health advocates have repeatedly highlighted parallels between food marketing and childhood obesity. Yet existing literature has not explored the connection between the promotion of unhealthy foods and beverages, certain characteristics of integrated marketing communication (IMC) and the power of multinational food and beverage companies. This is problematic because IMC represents the dominant marketing paradigm in use today. This article draws on critical theory and literature from across public health, marketing, business and related fields. By focusing on macro-level antecedents and interactions, this discussion highlights a previously unarticulated dimension of the promotion of unhealthy foods and beverages to children and adolescents. In doing so, this discussion aims to generate greater recognition of the broader environmental circumstances and processes that surround food marketing tactics and their consequences for public health nutrition. This perspective will also contribute to an expanded understanding of unhealthy food marketing and its unintended consequences, among an audience of nutrition, public health and policy communities.

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Highly pathogenic avian influenza virus infection is associated with severe mortality in both humans and poultry. The mechanisms of disease pathogenesis and immunity are poorly understood although recent evidence suggests that cytokine/chemokine dysregulation contributes to disease severity following H5N1 infection. Influenza A virus infection causes a rapid influx of inflammatory cells, resulting in increased reactive oxygen species production, cytokine expression, and acute lung injury. Proinflammatory stimuli are known to induce intracellular reactive oxygen species by activating NADPH oxidase activity. We therefore hypothesized that inhibition of this activity would restore host cytokine homeostasis following avian influenza virus infection. A panel of airway epithelial and immune cells from mammalian and avian species were infected with A/Puerto Rico/8/1934 H1N1 virus, low-pathogenicity avian influenza H5N3 virus (A/duck/Victoria/0305-2/2012), highly pathogenic avian influenza H5N1 virus (A/chicken/Vietnam/0008/2004), or low-pathogenicity avian influenza H7N9 virus (A/Anhui/1/2013). Quantitative real-time reverse transcriptase PCR showed that H5N1 and H7N9 viruses significantly stimulated cytokine (interleukin-6, beta interferon, CXCL10, and CCL5) production. Among the influenza-induced cytokines, CCL5 was identified as a potential marker for overactive immunity. Apocynin, a Nox2 inhibitor, inhibited influenza-induced cytokines and reactive oxygen species production, although viral replication was not significantly altered in vitro. Interestingly, apocynin treatment significantly increased influenza virus-induced mRNA and protein expression of SOCS1 and SOCS3, enhancing negative regulation of cytokine signaling. These findings suggest that apocynin or its derivatives (targeting host responses) could be used in combination with antiviral strategies (targeting viruses) as therapeutic agents to ameliorate disease severity in susceptible species.

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The Methods for compensation of harmonic currents and voltages have been widely used since these methods allow to reduce to acceptable levels the harmonic distortion in the voltages or currents in a power system, and also compensate reactive. The reduction of harmonics and reactive contributes to the reduction of losses in transmission lines and electrical machinery, increasing the power factor, reduce the occurrence of overvoltage and overcurrent. The active power filter is the most efficient method for compensation of harmonic currents and voltages. The active power filter is necessary to use current and voltage controllers loop. Conventionally, the current and voltage control loop of active filter has been done by proportional controllers integrative. This work, investigated the use of a robust adaptive control technique on the shunt active power filter current and voltage control loop to increase robustness and improve the performance of active filter to compensate for harmonics. The proposed control scheme is based on a combination of techniques for adaptive control pole placement and variable structure. The advantages of the proposed method over conventional ones are: lower total harmonic distortion, more flexibility, adaptability and robustness to the system. Moreover, the proposed control scheme improves the performance and improves the transient of active filter. The validation of the proposed technique was verified initially by a simulation program implemented in C++ language and then experimental results were obtained using a prototype three-phase active filter of 1 kVA

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This paper presents a novel single-phase high-power-factor (HPF) pulsewidth-modulated (PWM) boost rectifier featuring soft commutation of the active switches at zero current (ZC), It incorporates the most desirable properties of conventional PWM and soft-switching resonant techniques.The input current shaping is achieved with average current mode control and continuous inductor current mode.This new PWM converter provides ZC turn on and turn off of the active switches, and it is suitable for high-power applications employing insulated gate bipolar transistors (IGBT's),The principle of operation, the theoretical analysis, a design example, and experimental results from a laboratory prototype rated at 1600 W with 400-Vdc output voltage are presented. The measured efficiency and the power factor were 96.2% and 0.99%, respectively, with an input current total harmonic distortion (THD) equal to 3.94%, for an input voltage with THD equal to 3.8%, at rated load.

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The conventional Newton and fast decoupled power flow (FDPF) methods have been considered inadequate to obtain the maximum loading point of power systems due to ill-conditioning problems at and near this critical point. It is well known that the PV and Q-theta decoupling assumptions of the fast decoupled power flow formulation no longer hold in the vicinity of the critical point. Moreover, the Jacobian matrix of the Newton method becomes singular at this point. However, the maximum loading point can be efficiently computed through parameterization techniques of continuation methods. In this paper it is shown that by using either theta or V as a parameter, the new fast decoupled power flow versions (XB and BX) become adequate for the computation of the maximum loading point only with a few small modifications. The possible use of reactive power injection in a selected PV bus (Q(PV)) as continuation parameter (mu) for the computation of the maximum loading point is also shown. A trivial secant predictor, the modified zero-order polynomial which uses the current solution and a fixed increment in the parameter (V, theta, or mu) as an estimate for the next solution, is used in predictor step. These new versions are compared to each other with the purpose of pointing out their features, as well as the influence of reactive power and transformer tap limits. The results obtained with the new approach for the IEEE test systems (14, 30, 57 and 118 buses) are presented and discussed in the companion paper. The results show that the characteristics of the conventional method are enhanced and the region of convergence around the singular solution is enlarged. In addition, it is shown that parameters can be switched during the tracing process in order to efficiently determine all the PV curve points with few iterations. (C) 2003 Elsevier B.V. All rights reserved.

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This work describes a methodology for power factor control and correction of the unbalanced currents in four-wire electric circuits. The methodology is based on the insertion of two compensation networks, one wye-grounded neutral and another in delta, in parallel to the load. The mathematical development has been proposed in previous work [3]. In this paper, however, the methodology was adapted to accept different power factors for the system to be compensated. on the other hand, the determination of the compensation susceptances is based on the instantaneous values of the load currents. The results are obtained using the MatLab - Simulink environment.

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The parameterized fast decoupled power flow (PFDPF), versions XB and BX, using either theta or V as a parameter have been proposed by the authors in Part I of this paper. The use of reactive power injection of a selected PVbus (Q(PV)) as the continuation parameter for the computation of the maximum loading point (MLP) was also investigated. In this paper, the proposed versions obtained only with small modifications of the conventional one are used for the computation of the MLP of IEEE test systems (14, 30, 57 and 118 buses). These new versions are compared to each other with the purpose of pointing out their features, as well as the influence of reactive power and transformer tap limits. The results obtained with the new approaches are presented and discussed. The results show that the characteristics of the conventional FDPF method are enhanced and the region of convergence around the singular solution is enlarged. In addition, it is shown that these versions can be switched during the tracing process in order to efficiently determine all the PV curve points with few iterations. A trivial secant predictor, the modified zero-order polynomial, which uses the current solution and a fixed increment in the parameter (V, theta, or mu) as an estimate for the next solution, is used for the predictor step. (C) 2003 Elsevier B.V. All rights reserved.