3,535 research outputs found
In Situ Measurement of Wall Thermal Properties: Parametric Investigation of the Heat Flow Meter Methods through Virtual Experiments Data
No full textEnergy retrofit of existing buildings is based on the assessment of the starting performance of the envelope. The procedure for the in situ measurement of thermal conductance is described in the ISO 9869-1:2014, which provides two techniques for data processing: the average method (AM) and the dynamic method (DM). This work studies their effectiveness using virtual data from numerical simulations based on a finite difference model applied to different wall kinds, considering winter and summer boundary conditions alternatively (Italian Milan-Linate TMY). The estimated thermal conductances are compared to the reference theoretical values. The main purposes are: (i) defining the shortest test duration that provides acceptable results; (ii) assess the reliability of the criteria provided by the standard to evaluate the measurement quality; (iii) evaluate the sensitivity of both methods to variables such as wall properties, boundary conditions and others more specific to the DM (namely, the number of time constants and linear equations). The AM always provides acceptable estimates in winter (-3.1% divided by 10% error), with better outcomes when indoor heat flux is considered, except for the highly insulated wall, but is not effective in summer, despite the fulfillment of the acceptance criteria for the highly insulated wall. The DM provides improvements in both seasons (0.05% divided by 8.6% absolute values of error), for most virtual samples, and requires shorter sampling periods, even below the 3 days limit suggested by the standard. The test on the confidence interval indicated by the ISO 9869-1:2014 is not reliable and measurements are sensitive to the number of linear equations, that is left to the user's discretion without strict indications. This work suggests a possible approach for overcoming this issue, which requires deeper future investigation
In Situ Measurement of Wall Thermal Properties: Parametric Investigation of the Heat Flow Methods Through Virtual Experiments Data
No full textEnergy retrofit of existing buildings is based on the assessment
of the starting performance of the envelope. The procedure
to evaluate thermal conductance through in situ
measurements is described in the technical standard ISO
9869-1:2014, which provides two alternative techniques to
process collected data: the Average Method (AM) and the
Dynamic Method (DM).
This work studies their effectiveness using virtual data
from numerical simulations of three kinds of walls, performed
using a Finite Difference model.
The AM always provides acceptable estimates in winter,
with better outcomes when indoor heat flux is considered
in every case except the highly insulated wall. Summer
conditions do not lead to acceptable measurements, despite
the fulfillment of the check required by the standard.
The DM results show acceptable estimations of the thermal
conductance in both climates, for most of the virtual
samples considered, although critically depending on
some parameters of the DM that are left to the user’s discretion,
without strict indications by the standard. This
work highlights a possible approach for overcoming this
issue, which requires deeper future investigation
Decomposition processes and trace metals in muds of the Gulf of Papua, Papua New Guinea
No full textMaintenance and Update Frequency: notPlannedStatement: Statement: Methods and sensors are described in:Alongi DM, Boyle S, Tirendi F and Payne C (1996) Composition and behaviour of trace metals in post-oxic sediments of the Gulf of Papua. Estuarine Coastal and Shelf Science 42: 197-211.andAlongi DM (1995) Decomposition and recycling of organic matter in muds of the Gulf of Papua, northern Coral Sea. Continental Shelf Research 15: 1319-1337.<b>Credit</b><br/>Alongi, Daniel M, Dr (Principal Investigator)Nutrient chemistry and rates of nutrient regeneration were examined in muds of the Gulf of Paupa, Papua New Guinea. Samples were taken from 3 new sites (IGP1, IGP2, IGP3) and 2 sites previously sampled in 1990 (D9, GP8).Sedimentary variables were: temperature; grain size; salinity; porosity; and percent sand, silt and clay.Dissolved solute (DON, DOP, ammonium, nitrite, nitrate, phosphate, silicate, DOC, Fe, Mn) flux measurements and primary production (O2 flux) were made for each site.Cores were taken for measurements of solid-phase elements (TOC, TN, TP, TS) and porewater nutrients at each site.The concentrations of solid-phase and dissolved trace metals (Al, Fe, Mn, Mo, Ni, Cu, Co), including sediment-water interface, were measured.<br/> To describe rates of bacterial composition and recycling of organic matter in the upper sediment layers (0-20 cm) of these inner shelf muds and their contribution to primary pelagic production.To assess the role of post-oxic muds in the flux of trace metals into the Coral Sea.<br/> This research project was a component of a larger project to determine the influence of freshwater and detrital export from the Fly River system on adjacent pelagic and benthic systems
Benthic infauna and organism-sediment relations in a shallow, tropical coastal area: influence of outwelled mangrove detritus and physical disturbance
No full textCarbon and nutrient cycling in seagrass meadows, Sulawesi, Indonesia
No full textMaintenance and Update Frequency: notPlannedStatement: Statement: Methods and sensors as described in:Alongi DM, Trott LA, Undu MC and Tirendi F (2008) Benthic microbial metabolism in seagrass meadows along a carbonate gradient in Sulawesi, Indonesia. Aquatic Microbial Ecology 51: 141-152.<b>Credit</b><br/>Alongi, Daniel M, Dr (Principal Investigator)The study was conducted in 3 seagrass beds in Awerange Bay during the dry season (September 2006) and the wet season (March 2007).Densities of seagrass (shoots m-2) and production in(g DW m-2 d-1) were calculated.pH and redox potential were measured. Water content, total C, total N, TOC and total P were determined, and total inorganic carbon calculated.Rates of sulfate reduction were measured.Solute fluxes of DIC, O2, and dissolved inorganic nutrient and other solute (Ca, Fe, Mn, hydrogen sulphide) across the sediment-water interface were measured.Net ammonium production was measured from each site.Denitrification was measured using the N2-gas technique. Fluxes of methane and N2O were measured. Nitrogen fixation in sediments was also measured.Benthic microaglal production was measured by oxygen fluxes in the dry and wet seasons.<br/> To examine sediment carbon and nitrogen cycling in seagrass meadows across a gradient of increasing cabonate content
Entanglement and quantity in quantum space - About quantum measurement (II)
No full textAs a continuation and extension of "quantity in phase space" "quantity in quantum space" is introduced. With that, the disappearing of quantum interference discussed in a previous paper [S. Durr, et al., Nature 395 (1998) 33] is explained in the same spirit as our recent papers [Ren De-Ming, Commun. Theor. Phys. (Beijing, China) 41 (2004) 685, 833].Physics, MultidisciplinarySCI(E)中国科学引文数据库(CSCD)1ARTICLE133-364
Sneutrino DM in the NMSSM with inverse seesaw mechanism
No full textIn supersymmetric theories like the Next-to-Minimal Supersymmetric Standard Model (NMSSM), the lightest neutralino with bino or singlino as its dominant component is customarily taken as dark matter (DM) candidate. Since light Higgsinos favored by naturalness can strength the couplings of the DM and thus enhance the DM-nucleon scattering rate, the tension between naturalness and DM direct detection results becomes more and more acute with the improved experimental sensitivity. In this work, we extend the NMSSM by inverse seesaw mechanism to generate neutrino mass, and show that in certain parameter space the lightest sneutrino may act as a viable DM candidate, i.e. it can annihilate by multi-channels to get correct relic density and meanwhile satisfy all experimental constraints. The most striking feature of the extension is that the DM-nucleon scattering rate can be naturally below its current experimental bounds regardless of the higgsino mass, and hence it alleviates the tension between naturalness and DM experiments. Other interesting features include that the Higgs phenomenology becomes much richer than that of the original NMSSM due to the relaxed constraints from DM physics and also due to the presence of extra neutrinos, and that the signatures of sparticles at colliders are quite different from those with neutralino as DM candidate.National Natural Science Foundation of China (NNSFC) [11575053]SCI(E)ARTICLE1
Classical mechanics and quantum mechanics
No full textThe Newton equation of motion is derived from quantum mechanics.Physics, MultidisciplinarySCI(E)中国科学引文数据库(CSCD)2ARTICLE5685-6884
Policy-driven Data Sharing over Attribute-Based Encryption supporting Dual Membership
No full textAttribute-Based Encryption (ABE) plays an important role in current secure data sharing through fine-grained customizable policies. However, the existing ABE schemes only support simple predicates, = and ≠, but cannot express a more general membership predicates, ∈ and ∉, in policies. The low expressivity of ABE will enlarge the ciphertext storage and reduce the communication efficiency. To overcome this problem, we propose an ABE supporting Dual Membership (DM-ABE). The core problem for implementing this scheme is how to use cryptographic methods to decide the membership between the verified element and the given set. In order to solve this problem, we design a cryptographic algorithm, called Secure Decision of Membership (SDM), based on aggregation functions. In this algorithm, any set can be aggregated into one cryptographic element, and the verified element and the given set can be converted into another cryptographic element in decision process. The membership between them can be decided by the above two cryptographic elements. Furthermore, we construct the DM-ABE by using SDM. Because of the good expressivity of our DM-ABE, we further propose a novel cryptographic data sharing framework by integrating DM-ABE and attribute-based access control to provide fine-grained access control and security protection for private data. In the security proof of DM-ABE, we prove that the DM-ABE satisfies the semantic security against chosen-plaintext attacks under the DBDHE assumption in the standard model through a unified way, considering both two encryption methods for ∈ and ∉ at the same time. Finally, we analyze our scheme in terms of time and space complexity, and compare it with some existing schemes. The results show that our DM-ABE has a better expressive ability on the boolean logic of general membership predicates, ∈ and ∉.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Cyber Securit
Constraining the Inner Galactic DM Density Profile with H.E.S.S.
No full text© 2024 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).In this short review, corresponding to a talk given at the conference “Cosmology 2023 in Miramare”, we combine an analysis of five regions observed by H.E.S.S. in the Galactic Center, intending to constrain the Dark Matter (DM) density profile in a WIMP annihilation scenario. For the analysis, we include the state-of-the-art Galactic diffuse emission Gamma-optimized model computed with DRAGON and a wide range of DM density profiles from cored to cuspy profiles, including different kinds of DM spikes. Our results are able to constrain generalized NFW profiles with an inner slope ≳1.3 . When considering DM spikes, the adiabatic spike is completely ruled out. However, smoother spikes given by the interactions with the bulge stars are compatible if ≲0.8 , with an internal slope of sp-stars=1.5.This work has been supported by the grants PID2021-125331NB-I00, PID2022-139841NB-I00, and CEX2020-001007-S, funded by MCIN/AEI/10.13039/501100011033, by “ERDF A way of making Europe”, and the MULTIDARK Project RED2022-134411-T. The author’s contribution to this work has been supported by the FPI Severo Ochoa PRE2021-099137 grant.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2020-001007-S).Peer reviewe
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