94 resultados para Literature response
Resumo:
The relation of automatic auditory discrimination, measured with MMN, with the type of stimuli has not been well established in the literature, despite its importance as an electrophysiological measure of central sound representation. In this study, MMN response was elicited by pure-tone and speech binaurally passive auditory oddball paradigm in a group of 8 normal young adult subjects at the same intensity level (75 dB SPL). The frequency difference in pure-tone oddball was 100 Hz (standard = 1 000 Hz; deviant = 1 100 Hz; same duration = 100 ms), in speech oddball (standard /ba/; deviant /pa/; same duration = 175 ms) the Portuguese phonemes are both plosive bi-labial in order to maintain a narrow frequency band. Differences were found across electrode location between speech and pure-tone stimuli. Larger MMN amplitude, duration and higher latency to speech were verified compared to pure-tone in Cz and Fz as well as significance differences in latency and amplitude between mastoids. Results suggest that speech may be processed differently than non-speech; also it may occur in a later stage due to overlapping processes since more neural resources are required to speech processing.
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Although the issue of the out-of-plane response of unreinforced masonry structures under earthquake excitation is well known with consensus among the research community, this issue is simultaneously one of the more complex and most neglected areas on the seismic assessment of existing buildings. Nonetheless, its characterization should be found on the solid knowledge of the phenomenon and on the complete understanding of methodologies currently used to describe it. Based on this assumption, this article presents a general framework on the issue of the out-of-plane performance of unreinforced masonry structures, beginning with a brief introduction to the topic, followed by a compact state of art in which the principal methodologies proposed to assess the out-of-plane behavior of unreinforced masonry structures are presented. Different analytical approaches are presented, namely force and displacement-based, complemented with the presentation of existing numerical tools for the purpose presented above. Moreover, the most relevant experimental campaigns carried out in order to reproduce the phenomenon are reviewed and briefly discussed.
Resumo:
There has been a growing interest in research on performance measurement and management practices, which seems to reflect researchers’ response to calls for the need to increase the relevance of management accounting research. However, despite the development of the new public management literature, studies involving public sector organizations are relatively small compared to those involving business organizations and extremely limited when it comes to public primary health care organizations. Yet, the economic significance of public health care organizations in the economy of developed countries and the criticisms these organizations regularly face from the public suggests there is a need for research. This is particularly true in the case of research that may lead to improvement in performance measurement and management practices and ultimately to improvements in the way health care organizations use their limited resources in the provision of services to the communities. This study reports on a field study involving three public primary health care organisations. The evidence obtained from interviews and archival data suggests a performance management practices in these institutions lacked consistency and coherence, potentially leading to decreased performance. Hierarchical controls seemed to be very weak and accountability limited, leading to a lack of direction, low motivation and, in some circumstances to insufficient managerial abilities and skills. Also, the performance management systems revealed a number of weaknesses, which suggests that there are various opportunities for improvement in performance in the studied organisations.
Resumo:
A articulação tíbio-társica (tornozelo) é considerada uma das articulações mais relevantes e mais susceptível à lesão, sendo que a entorse do tornozelo consiste na lesão mais comum em desportistas, com uma percentagem de ocorrência de 35% no andebol. Este trabalho centra-se, assim, na problemática das entorses do tornozelo nos jogadores de andebol e da sua relação com o treino proprioceptivo como medida preventiva. O objectivo do presente trabalho foi a realização de uma revisão sistemática que estuda o treino proprioceptivo na prevenção da entorse do tornozelo, para isso, tentámos identificar a possível relação entre entorse do tornozelo e treino proprioceptivo. A metodologia utilizada neste trabalho foi uma revisão da literatura, sendo realizada uma pesquisa electrónica na base de dados da B-On, utilizando combinações de palavras-chave. No total resultaram 758 artigos, tendo sido pela sua relevância selecionados 29. Neste trabalho ficou evidente a relação do treino proprioceptivo com a prevenção da entorse do tornozelo. De todas as medidas preventivas o treino proprioceptivo é o que apresenta melhores resultados, pois, este tipo de treino está direccionado para uma estruturação da zona lesionada, fortalecendo os músculos e ligamentos, restaurando a componente proprioceptiva das estruturas danificadas e permitindo uma resposta mais rápida do Sistema Nervoso Central, aos vários estímulos a que está sujeito o atleta. Foi possível descrever em que consiste o treino proprioceptivo e os seus constituintes, adaptando-o ao andebol. Com esta revisão da literatura não foi possível obter um consenso sobre o efeito do treino proprioceptivo na prevenção de entorses do tornozelo.
Resumo:
As constantes alterações das realidades sociais e epidemiológicas em associação ao envelhecimento populacional conduziram a insuficiências dos Sistemas Social e de Saúde que requerem uma reestruturação ao nível da adequação dos cuidados de saúde a prestar, pelo que, em resposta a esta necessidade foi criada a Rede Nacional de Cuidados Continuados Integrados. O presente estudo, de natureza qualitativa e carácter exploratório, tem como objectivo compreender a percepção dos Terapeutas Ocupacionais que trabalham em Unidades de Cuidados Continuados Integrados relativamente às categorias que considerem mais relevantes da Classificação Internacional da Funcionalidade, Incapacidade e Saúde, tendo sido aplicada uma entrevista a 8 profissionais a exercer funções em Unidades da Zona Norte, resultante de um processo de amostragem não probabilística e de conveniência. Como método de recolha de dados foi aplicada uma entrevista semi-estruturada, cujo guião foi construído após revisão bibliográfica, tendo por base as categorias definidas pelo modelo da Classificação Internacional da Funcionalidade, Incapacidade e Saúde e, posteriormente, analisado por um painel de peritos, tendo-se procedido à realização de uma entrevista piloto a um elemento, sem que esta contasse para a análise. A partir da análise das entrevistas realizadas procedemos à identificação das unidades de significado, tendo os conceitos sido ligados às categorias da Classificação que o representam de uma forma mais adequada, de acordo com as linking rules, tendo sido identificadas as categorias mais relevantes para os Terapeutas Ocupacionais a exercer funções em Unidades de Cuidados Continuados Integrados. Com a realização deste estudo, que pretende ser um primeiro passo para a criação de um futuro Core Set em Cuidados Continuados, foi-nos possível verificar que o maior número de categorias foram observadas no componente Actividades e Participação, tendo sido contabilizadas 70 (40,7%). Por outro lado, o componente Estruturas do corpo é o que integra menor número, contando com 19 categorias (11,05%). Assim, pensamos que a criação de um Core Set em Cuidados Continuados poderá beneficiar e facilitar a comunicação entre os profissionais destas equipas. No entanto, é importante ressalvar que a terminologia desta Classificação deverá ser utilizada de uma forma concertada com a linguagem específica da Terapia Ocupacional. Palavras-chave: Classificação Internacional da Funcionalidade, Incapacidade e Saúde, Core Set, Terapeutas Ocupacionais, Unidades de Cuidados Continuados Integrados.
Resumo:
Purpose: To quantify the effect of unstable shoe wearing on muscle activity and haemodynamic response during standing. Methods: Thirty volunteers were divided into 2 groups: the experimental group wore an unstable shoe for 8 weeks, while the control group used a conventional shoe for the same period. Muscle activity of the medial gastrocnemius, tibialis anterior, rectus femoris and biceps femoris and venous circulation were assessed in quiet standing with the unstable shoe and barefoot. Results: In the first measurement there was an increase in medial gastrocnemius activity in all volunteers while wearing the unstable shoe. On the other hand, after wearing the unstable shoe for eight weeks these differences were not verified. Venous return increased in subjects wearing the unstable shoe before and after training. Conclusions: The unstable shoe produced changes in electromyographic characteristics which were advantageous for venous circulation even after training accommodation by the neuromuscular system.
Resumo:
Power systems have been suffering huge changes mainly due to the substantial increase of distributed generation and to the operation in competitive environments. Virtual power players can aggregate a diversity of players, namely generators and consumers, and a diversity of energy resources, including electricity generation based on several technologies, storage and demand response. Resource management gains an increasing relevance in this competitive context, while demand side active role provides managers with increased demand elasticity. This makes demand response use more interesting and flexible, giving rise to a wide range of new opportunities.This paper proposes a methodology for managing demand response programs in the scope of virtual power players. The proposed method is based on the calculation of locational marginal prices (LMP). The evaluation of the impact of using demand response specific programs on the LMP value supports the manager decision concerning demand response use. The proposed method has been computationally implemented and its application is illustrated in this paper using a 32 bus network with intensive use of distributed generation.
Resumo:
The introduction of Electric Vehicles (EVs) together with the implementation of smart grids will raise new challenges to power system operators. This paper proposes a demand response program for electric vehicle users which provides the network operator with another useful resource that consists in reducing vehicles charging necessities. This demand response program enables vehicle users to get some profit by agreeing to reduce their travel necessities and minimum battery level requirements on a given period. To support network operator actions, the amount of demand response usage can be estimated using data mining techniques applied to a database containing a large set of operation scenarios. The paper includes a case study based on simulated operation scenarios that consider different operation conditions, e.g. available renewable generation, and considering a diversity of distributed resources and electric vehicles with vehicle-to-grid capacity and demand response capacity in a 33 bus distribution network.
Resumo:
In competitive electricity markets with deep concerns for the efficiency level, demand response programs gain considerable significance. As demand response levels have decreased after the introduction of competition in the power industry, new approaches are required to take full advantage of demand response opportunities. Grid operators and utilities are taking new initiatives, recognizing the value of demand response for grid reliability and for the enhancement of organized spot markets’ efficiency. This paper proposes a methodology for the selection of the consumers that participate in an event, which is the responsibility of the Portuguese transmission network operator. The proposed method is intended to be applied in the interruptibility service implemented in Portugal, in convergence with Spain, in the context of the Iberian electricity market. This method is based on the calculation of locational marginal prices (LMP) which are used to support the decision concerning the consumers to be schedule for participation. The proposed method has been computationally implemented and its application is illustrated in this paper using a 937 bus distribution network with more than 20,000 consumers.
Resumo:
The design and development of simulation models and tools for Demand Response (DR) programs are becoming more and more important for adequately taking the maximum advantages of DR programs use. Moreover, a more active consumers’ participation in DR programs can help improving the system reliability and decrease or defer the required investments. DemSi, a DR simulator, designed and implemented by the authors of this paper, allows studying DR actions and schemes in distribution networks. It undertakes the technical validation of the solution using realistic network simulation based on PSCAD. DemSi considers the players involved in DR actions, and the results can be analyzed from each specific player point of view.
Using demand response to deal with unexpected low wind power generation in the context of smart grid
Resumo:
Demand response is assumed an essential resource to fully achieve the smart grids operating benefits, namely in the context of competitive markets. Some advantages of Demand Response (DR) programs and of smart grids can only be achieved through the implementation of Real Time Pricing (RTP). The integration of the expected increasing amounts of distributed energy resources, as well as new players, requires new approaches for the changing operation of power systems. The methodology proposed aims the minimization of the operation costs in a smart grid operated by a virtual power player. It is especially useful when actual and day ahead wind forecast differ significantly. When facing lower wind power generation than expected, RTP is used in order to minimize the impacts of such wind availability change. The proposed model application is here illustrated using the scenario of a special wind availability reduction day in the Portuguese power system (8th February 2012).
Resumo:
In competitive electricity markets with deep concerns at the efficiency level, demand response programs gain considerable significance. In the same way, distributed generation has gained increasing importance in the operation and planning of power systems. Grid operators and utilities are taking new initiatives, recognizing the value of demand response and of distributed generation for grid reliability and for the enhancement of organized spot market´s efficiency. Grid operators and utilities become able to act in both energy and reserve components of electricity markets. This paper proposes a methodology for a joint dispatch of demand response and distributed generation to provide energy and reserve by a virtual power player that operates a distribution network. The proposed method has been computationally implemented and its application is illustrated in this paper using a 32 bus distribution network with 32 medium voltage consumers.
Resumo:
The concept of demand response has a growing importance in the context of the future power systems. Demand response can be seen as a resource like distributed generation, storage, electric vehicles, etc. All these resources require the existence of an infrastructure able to give players the means to operate and use them in an efficient way. This infrastructure implements in practice the smart grid concept, and should accommodate a large number of diverse types of players in the context of a competitive business environment. In this paper, demand response is optimally scheduled jointly with other resources such as distributed generation units and the energy provided by the electricity market, minimizing the operation costs from the point of view of a virtual power player, who manages these resources and supplies the aggregated consumers. The optimal schedule is obtained using two approaches based on particle swarm optimization (with and without mutation) which are compared with a deterministic approach that is used as a reference methodology. A case study with two scenarios implemented in DemSi, a demand Response simulator developed by the authors, evidences the advantages of the use of the proposed particle swarm approaches.
Resumo:
Recent changes in power systems mainly due to the substantial increase of distributed generation and to the operation in competitive environments has created new challenges to operation and planning. In this context, Virtual Power Players (VPP) can aggregate a diversity of players, namely generators and consumers, and a diversity of energy resources, including electricity generation based on several technologies, storage and demand response. Demand response market implementation has been done in recent years. Several implementation models have been considered. An important characteristic of a demand response program is the trigger criterion. A program for which the event trigger depends on the Locational Marginal Price (LMP) used by the New England Independent System operator (ISO-NE) inspired the present paper. This paper proposes a methodology to support VPP demand response programs management. The proposed method has been computationally implemented and its application is illustrated using a 32 bus network with intensive use of distributed generation. Results concerning the evaluation of the impact of using demand response events are also presented.
Resumo:
The growing importance and influence of new resources connected to the power systems has caused many changes in their operation. Environmental policies and several well know advantages have been made renewable based energy resources largely disseminated. These resources, including Distributed Generation (DG), are being connected to lower voltage levels where Demand Response (DR) must be considered too. These changes increase the complexity of the system operation due to both new operational constraints and amounts of data to be processed. Virtual Power Players (VPP) are entities able to manage these resources. Addressing these issues, this paper proposes a methodology to support VPP actions when these act as a Curtailment Service Provider (CSP) that provides DR capacity to a DR program declared by the Independent System Operator (ISO) or by the VPP itself. The amount of DR capacity that the CSP can assure is determined using data mining techniques applied to a database which is obtained for a large set of operation scenarios. The paper includes a case study based on 27,000 scenarios considering a diversity of distributed resources in a 33 bus distribution network.