6,906 research outputs found

    Constraining the general reheating phase in the α\alpha-attractor inflationary cosmology

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    In this paper we constrain some aspects of the general postinflationary phase in the context of superconformal α\alpha-attractor models of inflation. In particular, we provide constraints on the duration of the reheating process, NrehN_{reh}, and on the reheating temperature, TrehT_{reh}, simulating possible and future results given by the next-generation of cosmological missions. Moreover, we stress what kinds of equation-of-state parameter, wrehw_{reh}, are favored for different scenarios. The analysis does not depend on the details of the reheating phase and it is performed assuming different measurements of the tensor-to-scalar ratio rr.Comment: 8 pages, 2 figure

    Analysis of heat transfer in different CPC solar collectors: A CFD approach

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    In this paper a methodology is proposed to estimate thermal heat losses inside compound parabolic collectors (CPC) to be used in designing and validating new collectors' concepts and materials. CFD simulations were carried out on different CPCs, taking into account the effective working conditions and the presence of radiative heat transfer as well as the absence of adiabatic walls. The CFD model was validated considering a previous work reported in literature. The results were employed to develop some correlations by interpolation of numerical data, to express the Nusselt number on the receiver. We used these correlations to calculate heat losses of the receiver and to show the influence of different parameters such as the shape of receiver itself, tilt angle and concentration ratio. The variation of terms of the correlation as a function of characteristic length and concentration was studied. These results might be employed for a preliminary estimation procedure of a CPC collector efficiency and to propose sizing criteria of general validity for this class of devices

    Budget impact analysis of apixaban to treat and prevent venous thromboembolism in Italy

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    BACKGROUND: Venous thromboembolism (VTE), a collective term for deep vein thrombosis (DVT) and pulmonary embolism (PE), is a serious vascular condition associated to high economic and clinical burden. Apixaban, a Novel Oral Anticoagulant (NOAC) has shown non-inferiority efficacy versus the current standard of care (low molecular weight heparin [LMWH]/vitamin K antagonist [VKA]) in the acute treatment and prevention of VTE and a significant reduction in the risk of bleeding.AIM: Evaluate the economic impact of the use of apixaban for treatment and prevention of DVT and PE from the perspective of the Italian National Health System (NHS).METHODS: A budget impact model was adapted in order to compare clinical outcomes and economic consequences associated to apixaban vs. LMWH/VKA and others NOACs over a three-year time horizon in the Italian setting. In the analysis two scenario were compared: status quo scenario without apixaban and an alternative scenario with apixaban. Only direct healthcare costs have been considered.RESULTS: Assuming a population of patients receiving apixaban over the first 3 years equal to 20,957, the introduction of apixaban is associated to an incremental saving of € 821,748 in the first years, € 1,250,454 in the second year, and € 1,866,466 in the third year. The total net saving over the 3-year period is € 3,938,668, which is a 2.47% decrease from the total budget for the status quo scenario without apixaban. This saving is mainly due to reduced VTE events and bleeds by apixaban. Indeed apixaban is associated with less VTE events (both fatal and non-fatal), less major bleeding and less Clinical Relevant Non Major (CRNM) bleeding with a total of 52 fatal events avoided.CONCLUSIONS: The listing of apixaban for the treatment of VTE (both DVT and PE) and the prevention of recurrent VTE provides both significant clinical advantages, in terms of deaths and events avoided, and economical advantages, consisting in a reduction in the total expenditure on the Italian NHS

    Validation & Verification of an EDA automated synthesis tool

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    Reliability and correctness are two mandatory features for automated synthesis tools. To reach the goals several campaigns of Validation and Verification (V&V) are needed. The paper presents the extensive efforts set up to prove the correctness of a newly developed EDA automated synthesis tool. The target tool, MarciaTesta, is a multi-platform automatic generator of test programs for microprocessors' caches. Getting in input the selected March Test and some architectural details about the target cache memory, the tool automatically generates the assembly level program to be run as Software Based Self-Testing (SBST). The equivalence between the original March Test, the automatically generated Assembly program, and the intermediate C/C++ program have been proved resorting to sophisticated logging mechanisms. A set of proved libraries has been generated and extensively used during the tool development. A detailed analysis of the lessons learned is reporte

    An area-efficient 2-D convolution implementation on FPGA for space applications

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    The 2-D Convolution is an algorithm widely used in image and video processing. Although its computation is simple, its implementation requires a high computational power and an intensive use of memory. Field Programmable Gate Arrays (FPGA) architectures were proposed to accelerate calculations of 2-D Convolution and the use of buffers implemented on FPGAs are used to avoid direct memory access. In this paper we present an implementation of the 2-D Convolution algorithm on a FPGA architecture designed to support this operation in space applications. This proposed solution dramatically decreases the area needed keeping good performance, making it appropriate for embedded systems in critical space application

    Electric field effects on the dynamics of bubble detachment from an inclined surface

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    An experimental apparatus to study bubble detachment from an inclined surface under the action of electric forces is described. It consists of a container filled with FC72 at room temperature and pressure where a train of gas bubbles is injected from an orifice. An electrostatic field can be imposed around the bubble, while the cell can be tilted from 0 to 90°. It is possible to study interface growth with the aid of high-speed cinematography. Since the interface is asymmetrical, a mirror system allowed to acquire, in the same frame, two images at 90° of the bubble. Different inclinations, injection rates and voltages were tested in order to couple the effects of shear gravity and electric field. Curvature and contact angles have been derived with appropriate interpolation methods of the profile. Force balances on the bubble were checked, finding an electric force, which, at first pulls the bubbles from the orifice, then pushes it against the surface. The motion of the center of gravity confirms this behaviour. A power balance has been developed to determine the energy contributions, revealing that surface growth incorporates both the effects of inlet power and electric field
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