476 research outputs found

    Evaluation of building envelope retrofit techniques for reducing energy needs for space cooling.

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    One of the fastest growing sources of new energy demand is space cooling. According to EU-studies a four-fold growth in air-conditioned space is likely to take place between 1990 and 2020. The energy savings achievable in the end-use space cooling depend on a number of variables related to the building envelope, the plants and to some extent the behaviour of occupants. They are hence complex to evaluate and consequently often underrepresented in energy efficiency programmes and National Plans. This paper is based on some preliminary results of the IEE project KeepCool 2. It discusses in particular: a methodology for bottom-up assessment of the energy savings related to "sustainable summer comfort" solutions; reference base case building typologies are analyzed in 5 European climates, and dynamic simulations are used to calculate the reductions in the energy need for cooling which can be achieved by specific retrofit actions (e.g. additions of effective solar protections, increased thermal insulation, night ventilation, increase of active mass by PCM, low solar absorbance surfaces,...); situations where mechanical cooling can be avoided are evaluated using the Adaptive Comfort model, according to the norm EN 15251. case studies of buildings with good summer comfort and low energy consumption performances, according to the ten steps of the KC2 procedure. the analysis of case studies of "comfort policies" adopted by public and private bodies to ensure summer comfort with low energy consumption (commitments to give priority to heat load reductions instead of introducing mechanical cooling, relaxed dress codes, low thermal insulation chairs, local air velocity increase)

    Simulation and evaluation of a new PET system based on liquid xenon as detection medium

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    présenté par J.P. CussoneauDue to its intrinsic physical properties, high density and atomic number, fast scintillation, high scintillation light yield and low ionization potential, liquid xenon is an excellent medium for the tracking and the accurate energy measurement of γ-rays in the MeV energy domain. The use of liquid xenon associated to a micro gap structure device[1] to measure 511 keV γ-rays in PET system is under investigation at Subatech. A Geant3 simulation of a full PET design made of lXe-TPC modules has been developed and the first estimations of the performances from a realistic detector are very promising: good overall sensitivity to 511 keV γ's (~ 93% for a 9 cm lXe module), good three-dimensional spatial resolution (250 µm FWHM, for first interaction vertex localization). The measurement of the 3 coordinates of the interaction vertices and the energy loss associated allow to reconstruct the correct Compton sequence of correlated annihilation γ-rays. Hence the capability to identify the first interaction vertex leads to major progresses in PET imaging: a parallax free PET tomograph with high detection sensitivity and spatial resolution. Moreover, such lXe-PET camera have an excellent rejection power on scattered events in 3D reconstruction mode

    MIMAC : A micro-tpc matrix for directional detection of dark matter

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    Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from background. However, this strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC project has been developed. It is based on a gaseous micro-TPC matrix, filled with CF4 and CHF3. The first results on low energy nuclear recoils (H, F) obtained with a low mono-energetic neutron field are presented. The discovery potential of this search strategy is discussed and illustrated by a realistic case accessible to MIMAC.Comment: 6 pages, Proc. of the fifth international symposium on large TPCs for low energy rare event detection, Paris, France, Dec. 2010. To appear in Journal of Physic

    Renal Cell Carcinoma with Angioleiomyoma-Like Stroma and Clear Cell Papillary Renal Cell Carcinoma: Exploring SDHB Protein Immunohistochemistry and the Relationship to Tuberous Sclerosis Complex

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    Renal cell carcinoma (RCC) with angioleiomyoma-like stroma appears to be molecularly distinct from clear cell RCC; however, its relationship to clear cell papillary RCC remains debated. Recent studies have found that similar tumors sometimes occur in patients with tuberous sclerosis complex (TSC), of which one study found unexpectedly negative succinate dehydrogenase (SDH) B immunostaining. We evaluated immunohistochemistry for SDHB in 12 apparently sporadic RCCs with angioleiomyoma-like stroma and correlated with clinical information for stigmata of TSC. Tumors were compared to a group of 16 clear cell papillary RCCs and 6 unclassified tumors with prominent stroma. With exception of 1 unclassified tumor, all exhibited at least focal cytoplasmic staining for SDHB protein, often requiring high magnification and better appreciated with increased antibody concentration. Detailed history information was available for 9/12 patients with smooth muscle-rich tumors, revealing no stigmata of undiagnosed TSC. Electron microscopy performed on 1 of these tumors revealed mitochondria to be very sparse, potentially accounting for the weak immunohistochemical labeling for SDHB protein. Weak SDHB immunostaining may represent another shared feature of RCC with angioleiomyoma-like stroma and clear cell papillary RCC, likely due to sparse mitochondria, strengthening the possible relationship of these entities. Although smooth muscle-rich tumors have been recently reported in patients with TSC, absence of staining in tumors with this pattern may not be specific for TSC. In tumors with pale or clear cytoplasm, immunohistochemical staining for SDHB should be interpreted with caution as evidence of abnormality in the SDH pathway

    A {\mu}-TPC detector for the characterization of low energy neutron fields

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    The AMANDE facility produces monoenergetic neutron fields from 2 keV to 20 MeV for metrological purposes. To be considered as a reference facility, fluence and energy distributions of neutron fields have to be determined by primary measurement standards. For this purpose, a micro Time Projection Chamber is being developed to be dedicated to measure neutron fields with energy ranging from 8 keV up to 1 MeV. In this work we present simulations showing that such a detector, which allows the measurement of the ionization energy and the 3D reconstruction of the recoil nucleus, provides the determination of neutron energy and fluence of these neutron fields

    Data acquisition electronics and reconstruction software for real time 3D track reconstruction within the MIMAC project

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    Directional detection of non-baryonic Dark Matter requires 3D reconstruction of low energy nuclear recoils tracks. A gaseous micro-TPC matrix, filled with either 3He, CF4 or C4H10 has been developed within the MIMAC project. A dedicated acquisition electronics and a real time track reconstruction software have been developed to monitor a 512 channel prototype. This autotriggered electronic uses embedded processing to reduce the data transfer to its useful part only, i.e. decoded coordinates of hit tracks and corresponding energy measurements. An acquisition software with on-line monitoring and 3D track reconstruction is also presented.Comment: Proceedings of TWEPP-11, Vienna, Austria, 26-30 September 201

    Micromegas detector developments for MIMAC

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    The aim of the MIMAC project is to detect non-baryonic Dark Matter with a directional TPC. The recent Micromegas efforts towards building a large size detector will be described, in particular the characterization measurements of a prototype detector of 10 Ă—\times 10 cm2^2 with a 2 dimensional readout plane. Track reconstruction with alpha particles will be shown.Comment: 8 pages, 7 figures Proceedings of the 3rd International conference on Directional Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 2011; corrections on author affiliation

    Probing the Local Velocity Distribution of WIMP Dark Matter with Directional Detectors

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    We explore the ability of directional nuclear-recoil detectors to constrain the local velocity distribution of weakly interacting massive particle (WIMP) dark matter by performing Bayesian parameter estimation on simulated recoil-event data sets. We discuss in detail how directional information, when combined with measurements of the recoil-energy spectrum, helps break degeneracies in the velocity-distribution parameters. We also consider the possibility that velocity structures such as cold tidal streams or a dark disk may also be present in addition to the Galactic halo. Assuming a carbon-tetrafluoride detector with a 30-kg-yr exposure, a 50-GeV WIMP mass, and a WIMP-nucleon spin-dependent cross-section of 0.001 pb, we show that the properties of a cold tidal stream may be well constrained. However, measurement of the parameters of a dark-disk component with a low lag speed of ~50 km/s may be challenging unless energy thresholds are improved.Comment: 38 pages, 15 figure
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