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Search Results: 1 - 10 of 313 matches for " Piva "
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Air-Water Cooling System for Switch-Mode Power Supplies  [PDF]
G. Casano, S. Piva
Journal of Electronics Cooling and Thermal Control (JECTC) , 2015, DOI: 10.4236/jectc.2015.53005
Abstract: The results are presented of an experimental investigation of heat transfer in an air-liquid cooling system for a Switch-Mode Power Supply (SMPS) for TV digital power amplifiers. Since these SMPSs are characterized by high power and high compactness, thereby making the standard cooling techniques difficult to be used, a new cooling system is developed, using water and air as the cooling media. The active components (MOSFETs) are cooled with a liquid cold-plate, the passive ones (condensers, transformers, coils) with an air flow, in turn cooled by the cold-plate. By inserting the cooling system in an experimental tool where it is possible to control the cooling water, measurements are made of temperature in the significant points of the SMPS. The electric efficiency is also measured. The evaluation of the thermal performance of this cooling system is useful in order to limit its maximum operational temperature. The efficacy of the cooling system is demonstrated; the trends of efficiency and power dissipation are evidenced.
O jovem Diderot e o ceticismo dos Pensamentos
Paulo Piva Lima Piva
DoisPontos , 2007,
Abstract: This article is about the presence, interpretation and dialogue with the scepticism in the beginning of Denis Diderot’s thought, particulary in his a Philosophicaly Thoughts, scene of a metaphysical and religious crises which precedes the formulation of his atheist materialism.
"S. Cristóv o" de E a de Queirós
Luiz Piva
Alfa : Revista de Linguística , 2001,
Abstract:
The effect of the stress far field on the crack tip behaviour
A. PIVA
Annals of Geophysics , 1979, DOI: 10.4401/ag-4727
Abstract: The boundary value problem of an infinite purely elastic sheet with a traction-free crack loaded with a uniform shear and biaxial tension at infinity is solved. It is shown that the singular terms of stress and displacement functions are inadequate to predict the direction of initial crack extension. The independence of the J vector of the biaxial parameter is also proved.
An Overview on Image Forensics
Alessandro Piva
ISRN Signal Processing , 2013, DOI: 10.1155/2013/496701
Abstract:
An Overview on Image Forensics
Alessandro Piva
ISRN Signal Processing , 2013, DOI: 10.1155/2013/496701
Abstract: The aim of this survey is to provide a comprehensive overview of the state of the art in the area of image forensics. These techniques have been designed to identify the source of a digital image or to determine whether the content is authentic or modified, without the knowledge of any prior information about the image under analysis (and thus are defined as passive). All these tools work by detecting the presence, the absence, or the incongruence of some traces intrinsically tied to the digital image by the acquisition device and by any other operation after its creation. The paper has been organized by classifying the tools according to the position in the history of the digital image in which the relative footprint is left: acquisition-based methods, coding-based methods, and editing-based schemes. 1. Introduction Images, unlike text, represent an effective and natural communication media for humans, due to their immediacy and the easy way to understand the image content. Historically and traditionally, there has been confidence in the integrity of visual data, such that a picture printed in a newspaper is commonly accepted as a certification of the truthfulness of the news, or video surveillance recordings are proposed as probationary material in front of a court of law. With the rapid diffusion of inexpensive and easy to use devices that enable the acquisition of visual data, almost everybody has today the possibility of recording, storing, and sharing a large amount of digital images. At the same time, the large availability of image editing software tools makes extremely simple to alter the content of the images, or to create new ones, so that the possibility of tampering and counterfeiting visual content is no more restricted to experts. Finally, current software allows to create photorealistic computer graphics that viewers can find indistinguishable from photographic images [1, 2] or also generate hybrid generated visual content. In summary, today a visual digital object might go during its lifetime, from its acquisition to its fruition, through several processing stages, aimed at enhancing the quality, creating new content by mixing pre existing material, or even tampering with the content. As a consequence of all previous facts, doctored images are appearing with a growing frequency in different application fields, and thus today’s digital technology has begun to erode the trust on visual content, so that apparently “seeing is no longer believing” [3–5]. All these issues will get worse as processing tools become more and more sophisticated.
Experimental Investigation of the Fluid Dynamics of a Finned Heat Sink under Operating Conditions  [PDF]
G. Casano, M. W. Collins, S. Piva
Journal of Electronics Cooling and Thermal Control (JECTC) , 2014, DOI: 10.4236/jectc.2014.43010
Abstract: An experimental study has been made of the fluid dynamics performance of electronic equipment designed to cool a heat sink in the form of a finned duct. The apparatus consists of a channel of rectangular section containing the finned duct. A forced airflow is driven by three fans placed in parallel in the inlet and in the outlet sections of the channel. In order to investigate a full range of flow rates, different sets of fans were used in the inlet section. Measurements were made of static pressures at different channel positions by pressure taps connected to a micro manometer, and of the flow rate by a Venturi meter. The experimental working conditions of the active fans were consistent with the manufacturers’ characteristic curves. Values of the local friction coefficient compared well with published correlations. The experimental working points agreed very well with the theoretical curve of the pressure drop and the hydraulic diameter was demonstrated to be of the appropriate size for this fluid dynamics problem.
Where did all the aid go? an in-depth analysis of increased health aid flows over the past 10 years
Piva,Paolo; Dodd,Rebecca;
Bulletin of the World Health Organization , 2009, DOI: 10.1590/S0042-96862009001200013
Abstract: objective: to examine how health aid is spent and channelled, including the distribution of resources across countries and between subsectors. our aim was to complement the many qualitative critiques of health aid with a quantitative review and to provide insights on the level of development assistance available to recipient countries to address their health and health development needs. methods: we carried out a quantitative analysis of data from the aggregate aid statistics and creditor reporting system databases of the organisation for economic co-operation and development, which are the most reliable sources of data on official development assistance (oda) for health from all traditional bilateral and multilateral sources and from partnerships such as the global fund to fight aids, tuberculosis and malaria. findings: the analysis shows that while health oda is rising and capturing a larger share of total oda, there are significant imbalances in the allocation of health aid which run counter to internationally recognized principles of "effective aid". countries with comparable levels of poverty and health need receive remarkably different levels of aid. funding for millennium development goal 6 (combat hiv/aids, malaria and other diseases) accounts for much of the recent increase in health oda, while many other health priorities remain insufficiently funded. aid is highly fragmented at country level, which entails high transaction costs, divergence from national policies and lack of coherence between development partners. conclusion: although political momentum towards aid effectiveness is increasing at global level, some very real aid management challenges remain at country level. continued monitoring is therefore necessary, and we recommend that a review of the type presented here be repeated every 3 years.
Acesso, utiliza??o e aceita??o dos servi?os de dermatologia de um Centro de Saúde Escola sob o modo de ver dos hansenianos
Adami, Nilce Piva;
Revista Latino-Americana de Enfermagem , 1993, DOI: 10.1590/S0104-11691993000200005
Abstract: the present case study intends to analyze the access, utilization and acceptance of the dermatology services of a shc based mainly in the orally reported histories of 27 patients affected by hansen's disease. the access to shc - concerning its organization - took place without difficulty, except for the attendance services. however; the utilization level of the services was found to be higher than the established pattern of the care provided whether in actual episodes of the disease or not. the acceptance of the services rendered was consensual and both the technical quality and interpersonal relationship were emphasized.
The Esr Test: An Old Test With New Contents
Elisa Piva, Mario Plebani
Journal of Medical Biochemistry , 2010, DOI: 10.2478/v10011-010-0035-6
Abstract: The erythrocyte sedimentation rate (ESR) remains one of the most widely used laboratory tests. Its clinical usefulness and interpretation are in the monitoring of inflammatory diseases, in particular rheumatoid arthritis, temporal arteritis and polymyalgia rheumatica. At present, the reference method for measuring the ESR proposed by the International Committee for Standardization in Haematology (ICSH) utilizes EDTA-anticoagulated-undiluted blood to perform the test using the method described by Westergren in 1921. Current interest in the methodology focuses on the development of an automated closed system that allows the determination of the sedimentation rate with selected working methods, using a single sample for more than one haematological test, improving the bio-hazardous aspects of the testing procedures. As a consequence, standardization becomes necessary. ESR results should be reliable, despite the increased number of different methods and testing variables. Control materials and External Quality Assurance Schemes are now available, and should be used. In conclusion, innovative techniques may improve the appropriateness and usefulness of ESR in clinical practice, but in addition, they need to guarantee the traceability of results in comparison to the reference method in order to ensure comparability of results among different clinical laboratories.
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