579 resultados para Steering.
Resumo:
This article presents an array antenna with beam-steering capability in azimuth over a wide frequency band using real-valued weighting coefficients that can be realized in practice by amplifiers or attenuators. The described beamforming scheme relies on a 2D (instead of 1D) array structure in order to make sure that there are enough degrees of freedom to realize a given radiation pattern in both the angular and frequency domains. In the presented approach, weights are determined using an inverse discrete Fourier transform (IDFT) technique by neglecting the mutual coupling between array elements. Because of the presence of mutual coupling, the actual array produces a radiation pattern with increased side-lobe levels. In order to counter this effect, the design aims to realize the initial radiation pattern with a lower side-lobe level. This strategy is demonstrated in the design example of 4 X 4 element array. (C) 2005 Wiley Periodicals. Inc.
Resumo:
This article presents the design of a wideband rectangular array of planar monopoles, which is able to steer its beam and nulls over a wide frequency band using real-valued weights. These weights can be realized in practice by amplifiers or attenuators leading to a low cost development of a wideband array antenna with beam and null steering capability. The weights are determined by applying an inverse discrete Fourier transform to an assumed radiation pattern. This wideband beam and null forming concept is verified by full electromagnetic simulations which take into account mutual coupling effects between the array elements.
Resumo:
How does the non-executant state ensure that its agents are fulfilling their obligations to deliver nationally determined policies? In the case of elected local government in England and Wales, this function is carried out by the Audit Commission (AC) for Local Authorities and the Health Service for England and Wales. Since being established in 1983, it is the means by which local authorities are held to account by central government, both for its own purposes and on behalf of other interested stakeholders. Although the primary function of the AC is to ensure that local authorities are fulfilling their obligations, it does so by using different methods. By acting as a regulator, an independent expert, an opinion former and a mediator, the AC steers local authorities to ensure that they are compliant with the regulatory regime and are implementing legislation properly.
Resumo:
Since the 1980s UK government enthusiasm for market reforms has reconfigured the nature and scope of public services. Initially the marketisation of public services changed how public services were provided, increasingly market reforms and pro business policies have also modified the formation and understanding of public policy problematics and how they ought to be resolved. This is particularly noticeable when markets work imperfectly or even fail. UK governments have shown their reluctance to employ regulatory instruments to change the behaviour of companies preferring instead to make use of softer interventions, by focusing on providing advice for consumers and urging individuals to act responsibly. The dilemmas of this approach are explored by discussing the UK's former Labour government's (1997–2010) response to the increase in the incidence of obesity and related health complications.
Resumo:
Swallowable capsule endoscopy is used for non-invasive diagnosis of some gastrointestinal (GI) organs. However, control over the position of the capsule is a major unresolved issue. This study presents a design for steering the capsule based on magnetic levitation. The levitation is stabilized with the aid of a computer-aided feedback control system and diamagnetism. Peristaltic and gravitational forces to be overcome were calculated. A levitation setup was built to analyze the feasibility of using Hall Effect sensors to locate the in- vivo capsule. CAD software Maxwell 3D (Ansoft, Pittsburgh, PA) was used to determine the dimensions of the resistive electromagnets required for levitation and the feasibility of building them was examined. Comparison based on design complexity was made between positioning the patient supinely and upright.