This research work aims at evaluating the acoustic performance of conventional and low height gabions noise barriers. On one hand, in situ as well as scale model measurements at a scale of 1:10 have ...been carried out to assess the intrinsic acoustic properties of a 3m high gabions barrier. Single number ratings of transmission and reflection indices reached 20dB and 5dB, respectively. On the other hand, numerical simulations using a 2D boundary element method (BEM) and scale model measurements are carried out to study the effectiveness of low height gabions noise barriers when they are inserted in dense urban areas. The agreement between numerical and scale model measurements results is satisfactory. The effectiveness of low height gabions noise barriers is significant for receivers of limited height and the insertion loss values can reach 8dB(A) behind the barrier. This confirms that gabions noise barriers are possible candidates as useful devices for environmental noise reduction.
Passive houses have, at design stage, to fulfill a number of performance criteria. One of them imposes the normalized theoretical heat demand to be limited to 15 kWh/m2, year. In operation, it is ...very difficult to check, from simple observations or measurements, the real performance of such a house: different energy vectors may be used to meet the space heating as well as the domestic hot water demand, a storage tank may be used and fed by different energy sources (heat pump, direct electricity, solar thermal). The problem is still more complicated if the house is equipped with PV panels which naturally decrease the apparent electrical consumption. In the frame of the IEA Annex 58 project, a passive house was the object of a detailed analysis aiming at estimating the different terms of the energy balance. Some terms were results of direct in situ measurements and unmeasured terms such as solar and internal gains were estimated by dynamic simulation. The combination of measurements and simulation results allowed a reconstruction of a robust energy balance. The paper provides a detailed description of the approach and of each term of the rebuilt energy balance.
Engineered nanoporous particles have become an important class of nanostructured materials that have been increasingly applied in energy, biomedical, and environmental researches and industries. The ...internal pore surfaces in the particles can be chemically functionalized for environmental applications to sequestrate metals and radionuclide contaminants from groundwater. The fate and transport of the nanoporous particles in subsurface environments, however, have not been studied. Here we present a scanning optical fiber fluorescence profiler that can be used to in situ monitor the transport of fluorescent particles in column systems. Engineered nanoporous silicate particles (ENSPs) that were covalently bounded with fluorescence-emitting, and uranium-chelating ligands in the intraparticle pore domains were synthesized and used as an example to investigate nanoporous particle transport and to demonstrate the application of the developed in situ measurement profiler. The profiler detected an “irreversible” or slowly detached fraction of ENSPs in a sand collector even under thermodynamically unfavorable conditions for particle attachment. Further, the in situ measurement system detected the spatial variability of ENSPs transport that deviated from one-dimensional, homogeneous assumption, which is typically used to model particle transport in column systems. Generally, however, both measured and model-calculated results indicated that the transport of ENSPs was consistent with that of nonporous colloidal particles subjected to coupled reversible attachment/detachment and straining processes. The developed system can also be applied to detect other fluorescent nanostructured or colloidal particles in porous media.
Pitting corrosion of pure iron in borate buffer solution was studied by in-situ technics using chloride isotope 36Cl. Relationships between chloride ion concentration and current density in pit ...during pitting corrosion was discussed. Some results are summarized as follows. (1) Pits growth process is divided into two steps by the variation of chloride ion concentration and pitting current with time. The first step: chloride ion concentration on a pit surface (γp) increases linearly with time while the current density (ip) stays constant. The second step: γp stays at a constant, on the other hand, ip decreases gradually with time. (2) Both of γp and ip increase with external electrode potential. (3) Also γp and ip increase with a logarithmic low of the chloride ion concentration in a bulk solution.
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