Polarization Behaviours at 2, 5 and 60 GHz for Indoor Mobile Communications

The behaviours of linear polarizations at 2.15, 5.3 and 61.7 GHz in corridors are studied in this paper. It shows that there is no significant difference between the received powers for vertical and horizontal polarizations. Depolarization is obvious at 2.15 GHz due to different antenna type is applied at the receiver, and it is more serious in non-line-of-sight (NLOS) cases.     

Stochastic modelling for the analysis of blowout risk in exploration drilling

This article discusses the theoretical basis and the general framework related to stochastic blowout modelling in an offshore risk management context. The general scope is put forward by the Norwegian Petroleum Directorate (NPD) and the operating companies' need for an adequate decision making tool that permits studies of the effects of implemented risk reducing measures based on local conditions. Previous work and today's practices regarding stochastic modelling for the analysis of blowout risk are reviewed and discussed. Moreover, a different and perhaps more thorough approach to blowout risk modelling in exploration drilling is suggested that is based upon physical causal mechanisms and expert judgements combined with hard data rather than world wide blowout statistics.     

Tumor therapy with an antibody-targeted superantigen generates a dichotomy between local and systemic immune responses

Repeated injections of a fusion protein containing the superantigen staphylococcal enterotoxin A (SEA) combined with a Fab fragment of a tumor-specific antibody is a highly efficient immunotherapy for mice expressing lung melanoma micrometastasis. In the present study, the systemic and local immune responses generated by this therapy were analyzed at a cellular level. Two distinct but coupled immune reactions occurred after repeated therapy. Tumor necrosis factor and macrophage inflammatory protein-1 alpha and -1 beta were immediately synthesized, in the absence of T lymphocytes, at the local tumor site in the lung. This was followed by the induction of VCAM-1 adhesion molecule expression on pulmonary vascular endothelial cells. Concurrently, the early response in the spleen was characterized by the induction of selective T cells producing interleukin (IL)-2. The primed and expanded SEA-reactive V beta 3- and V beta 11-expressing T lymphocytes accumulated to the tumor area only after Fab-SEA therapy and were not present in the lung when SEA, Fab fragment, or recombinant IL-2 was injected. The tumor-infiltrating T cells produced large amounts of interferon-gamma, but no IL-2 or Th2 type of lymphokines were detected at the tumor site in the Fab-SEA-targeted antitumor immune response. These results emphasize the necessity to investigate several sites of antigen presentation to elucidate the effects of immunotherapy.     

Scale space multiresolution analysis of random signals

A method to capture the scale-dependent features in a random signal is proposed with the main focus on images and spatial fields defined on a regular grid. A technique based on scale space smoothing is used. However, while the usual scale space analysis approach is to suppress detail by increasing smoothing progressively, the proposed method instead considers differences of smooths at neighboring scales. A random signal can then be represented as a sum of such differences, a kind of a multiresolution analysis, each difference representing details relevant at a particular scale or resolution. Bayesian analysis is used to infer which details are credible and which are just artifacts of random variation. The applicability of the method is demonstrated using noisy digital images as well as global temperature change fields produced by numerical climate prediction models.     

Techno-economic analysis of a local district heating plant under fuel flexibility and performance

Brovst is a small district in Denmark. This paper analyses the use of local renewable resources in the district heating systems of Brovst. The present use of fossil fuels in the Brovst district heating plant (DHP) represents an increasing environmental and climate-related load. Therefore, an investigation has been made to reduce the use of fossil fuels for district heating system and make use of the local renewable resources (biogas, solar, and heat pump) for district heating purposes. In this article, the techno-economic assessment is achieved through the development of a suite of models that are combined to give cost and performance data for this district heating system. Local fuels have been analyzed for different perspectives to find the way to optimize the whole integrated system in accordance with fuel availability and cost. This paper represents the energy system analysis mode, energyPRO, which has been used to analyze the integration of a large-scale energy system into the domestic district heating system. A model of the current work on the basis of information from the Brovst plant (using fossil fuel) is established and named as a reference option. Then, four other options are calculated using the same procedure according to the use of various local renewable fuels known as “biogas option,” “solar option,” “heat pump option,” and “imported heat option.” A comparison has been made between the reference option and other options. The greatest reduction in heat cost is obtained from the biogas option by replacing a new engine, where 66 % of the current fuel is substituted with biogas.     

Thermal effect of a thermoelectric generator on parallel microchannel heat sink

Thermoelectric generators (TEG) convert heat energy to electrical power by means of semiconductor charge carriers serving as working fluid. In this work, a TEG is applied to a parallel microchannel heat sink. The effect of the inlet plenum arrangement on the laminar flow distribution in the channels is considered at a wide range of the pressure drop along the heat sink. The particular focus of this study is geometrical effect of the TEG on the heat transfer characteristics in the micro-heat sink. The hydraulic diameter of the microchannels is 270 μm, and three heat fluxes are applied on the hot surface of the TEG. By considering the maximum temperature limitation for Bi₂Te₃ material and using the microchannel heat sink for cooling down the TEG system, an optimum pumping power is achieved. The results are in a good agreement with the previous experimental and theoretical studies.     

The relationship between chord length and rime icing on wind turbines

Numerical simulations of ice accumulation on four different wind turbine blade profiles, from 450 kW, 600 kW, 1 MW and 2 MW, fixed speed, stall controlled, wind turbines, were performed to determine how wind turbine size affects atmospheric icing. The simulations indicate that dry rime icing is less severe for larger wind turbines both in terms of local ice mass and in terms of relative ice thickness. Copyright © 2009 John Wiley & Sons, Ltd.