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- 2018
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The influence of the thermal wake due to pulsating optical discharge on the aerodynamic-drag force
摘要： The influence of a thermal wake due to gas injection and due to a pulsating optical discharge (POD) on the aerodynamic-drag force of a body in a supersonic air flow with Mach number M = 1.45 are experimentally examined. With the help of a single-component aerodynamic balance, the influence of the injected subsonic jet and the thermal wake produced by POD on the aerodynamic drag of a hemisphere-on-cylinder model was studied. It is shown that the observed aerodynamic-force reduction phenomenon can be made more pronounced by increasing the laser power and pulse repetition frequency, or by decreasing the distance between the model and the pulsating optical discharge. The maximum aerodynamic-force reduction (up to 15%) due to the thermal-wake action was observed at a maximum laser-radiation power of W = 2.3 kW and at a pulse rate of f = 90 kHz. The joint effect due to the argon jet and due to the POD caused an aerodynamic-drag force reduction reaching 30%.
关键词： thermal wake,gas injection,CO2-laser,supersonic flow,pulsating optical discharge,aerodynamic-drag force
更新于2025-09-23 15:23:52
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A Temperature-Dependent X-Ray Absorption Characterization of Test Filters for the ATHENA Mission X-IFU Instrument
摘要： In order to work properly, the X-ray Integral Field Unit of the ATHENA mission requires a set of thermal ?lters that block the infrared radiation, preventing it to reach the detector. Each ?lter will be mounted and thermally anchored onto a shield of the multistage cryostat and will be kept at the speci?c temperature of the stage. On the other hand, the ?lters partially absorb X-rays, and their transmittance has to be carefully characterized. The effect of temperature on the absorption edges of the elements that make up the ?lters has not been investigated yet. Here, we report the results of a preliminary run on the optical transmission data around the edges of C, N, and O at different temperatures for a selected test sample with 500 nm of polyimide and 100 nm of aluminum.
关键词： K-edge,X-IFU,ATHENA,Thermal ?lters
更新于2025-09-23 15:23:52
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Performance Evaluation of Short Parabolic Trough Collectors Integrated with a Small-Scale Solar Power and Heating System
摘要： An investigation is presented on the performance of a small-scale solar power and heating system with short parabolic trough collectors (PTCs). The steady-state model of the short PTCs is evaluated with outside experiments. The model mainly contains the heat loss of the receiver, the peak optical efficiency and the incident angle factor consisting of incident angle modifier and end loss. It is found that the end loss effect is essential in this model when the length of the PTCs is less than 48 m, especially in the winter. The standard deviation of the steady-state model is 1.4%. Moreover, the potential energy efficiency ratio of the solar power and heating system is considerably larger than the coefficient of performance (COP) of general air-source heat pumps, and increases with the decrease of the condensation temperature. An overall system efficiency of 49% can be reached. Lastly, the existence of a water storage tank improves the flexibility of heating the building, and the volume of the water storage tank decreases with the increase of the heating water temperature.
关键词： practical operating characteristics,parabolic trough solar collector,thermal performance,testing method,small-scale
更新于2025-09-23 15:23:52
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Structural and Superconducting Properties of Thermal Treatment-Synthesised Bulk YBa2Cu3O7?δ Superconductor: Effect of Addition of SnO2 Nanoparticles
摘要： YBa2Cu3O7?δ (Y-123) bulk superconductors with the addition of (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 wt.%) SnO2 nanoparticles were synthesised via a thermal treatment method. The in?uence of SnO2 addition on the superconducting properties by means of critical temperature, Tc, AC susceptibility, phase formation and microstructures, including its elemental composition analysis, were studied. Sharp superconducting transition, ?Tc, and diamagnetic transition were obtained for all SnO2-added samples. It was observed that sample x = 0.4 with a Y-123 phase percentage of 95.8% gives the highest Tc, smallest ?Tc, and the sharpest diamagnetic transition in the normalised susceptibility curves. The microstructure also showed an excess of Sn precipitates on the sample’s surface at x = 0.8 and above. As such, the best superconducting properties were observed at x = 0.4 SnO2 addition inside the Y-123 host sample.
关键词： YBa2Cu3O7?δ,bulk superconductor,additions,SnO2,thermal treatment method
更新于2025-09-23 15:23:52
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A performance and technoeconomic study of different geometrical designs of compact single-pass cross-matrix solar air collector with square-tube absorbers
摘要： This manuscript presents a performance study on a forced convection single-pass solar air heater channel with compact cross-matrix absorber (CMA) incorporating metal hollow square-tube absorbers. Four different geometries of CMA (Type I, II, III and IV) were investigated experimentally to evaluate their efficiency, pressure drops and heat transfer parameters. The experiments were conducted with uniform heat flux (indoor) and outdoor solar radiation as heat source. The air mass flow rates used were between 0.0142 kg/s and 0.0360 kg/s. Techno-economic feasibility studies were conducted using cost-benefit ratio (AC/AEG) method. Thermal efficiency of the CMA obtained by Type I with 76%, being the highest. CMA Type I also exhibited the highest temperature elevation than other configurations with 15.3 °C and thermal capacity of 38.7 kJ. Maximum pressure drop obtained was 1.33 Pa in turbulent condition with Reynolds number of 50,794. Type I has the advantage of high performance CMA and has comparatively lower cost-benefit ratio (AC/AEG) of 0.15 RM/kWh than other type of thermal absorbers.
关键词： Thermal absorber design,Solar air collector,Cross-matrix absorber
更新于2025-09-23 15:23:52
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Contributed Review: The saga of neutrinoless double beta decay search with TeO <sub/>2</sub> thermal detectors
摘要： Neutrinoless double beta decay (0ν β β) is a direct probe of physics beyond the standard model. Its discovery would demonstrate that the lepton number is not a symmetry of nature and would provide us with unique information on the nature and mass of the neutrinos. Among the experimental techniques employed in the investigation of this rare process, thermal detectors fulfill the requirements for a powerful search, showing an excellent energy resolution and the possibility of scaling to very large masses. In this work, we review the long chain of bolometric experiments based on TeO2 crystals that were and continue to be carried out at the Laboratori Nazionali del Gran Sasso (Italy), searching for 0ν β β of 130Te. We illustrate the progress and improvements achieved in almost thirty years of measurements and compare the various performance and results. We describe the several steps that led to the CUORE detector, the latest of this series and presently in data taking, and we highlight the challenges that a next bolometric experiment will face in order to further improve the sensitivity, especially concerning the background abatement. Finally, we emphasize the advantages of 130Te in the search for 0ν β β with a further future experiment.
关键词： background reduction,TeO2 crystals,bolometers,neutrinoless double beta decay,CUORE,thermal detectors
更新于2025-09-23 15:23:52
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Antimicrobial-Peptide-Conjugated MoS2 Based Nanoplatform for Multimodal Synergistic Inactivation of Superbugs
摘要： Development of new antibacterial therapeutics material is becoming increasingly urgent due to the huge threat of superbugs, which are responsible for more than half million death each year in this world. Here, we report the development of novel nano-biomaterial based on melittin antimicrobial peptide (AMP) attached transition metal dichalcogenide MoS2 based theranostic nanoplatform. Reported nanoplatform has capability for targeted identification and synergistic inactivation of 100% multidrug-resistant superbugs by combined photo thermal therapy (PTT), photodynamic therapy (PDT) and AMP process. A novel approach for the design of melittin antimicrobial peptide attached MoS2 based nanoplatform is reported, which emits very bright and photo stable fluorescence. It also generates heat as well as reactive oxygen species (ROS) in the presence of 670 nm near infrared light, which allow it to be used as PTT & PDT agent. Due to the presence of AMP, multifunctional AMP exhibits significantly improved antibacterial activity for superbugs via multimodal synergistic killing mechanism. Reported data demonstrate that nanoplatforms are capable of identification of multidrug-resistant superbugs via luminescence imaging. Experimental results show that it is possible to kill only ~45% of superbugs via MoS2 nanopaltform based on PTT & PDT processes together. On the other hand, killing of less than 10% of superbugs is possible using melittin antimicrobial peptide alone. Whereas, 100% Methicillin-resistant Staphylococcus aureus (MRSA), drug resistance Escherichia coli (E. coli) and drug resistance Klebsiella pneumoniae (KPN) superbugs can be killed using antimicrobial peptide attached MoS2 QDs, via synergistic killing mechanism. Mechanisms for possible synergistic killing of multidrug-resistant superbugs have been discussed.
关键词： theranostic transition metal dichalcogenide,photodynamic therapy,multimodal therapy for multidrug-resistant superbugs,Melittin antimicrobial peptide attached MoS2 based nanoplatform,photo thermal therapy
更新于2025-09-23 15:23:52
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Evaluation of the temperature pattern of a complex body from thermal imaging and 3D information: A method and its MATLAB implementation
摘要： The standard setting of a camera used in Infrared thermography (IRT) is based on the choice of the same values of emissivity and distance for all pixels of a thermal image even if the emissivity depends on the relative position of camera and observed surface. Often this is not a problem. However, the resulting temperature pattern could be inadequate if a body having a complex shape is observed from strongly constrained positions. In order to face this issue, a procedure aimed at providing a correct temperature pattern by using 3D information related to a point cloud is proposed together with its MATLAB implementation (COMAP3 toolbox). For each pixel of a thermal image, the relative position of camera and observed surface is estimated, leading to pixel-specific values of emissivity and distance. The temperature obtained in this way is also mapped onto the point cloud. The effectiveness of the procedure in recognizing areas characterized by peculiar thermal behavior is shown in the case of a historic cylindrical masonry bell tower (Caorle’s bell tower, Venice, Italy).
关键词： Damage recognition,3D thermography,In situ measurements,Thermal imaging,Radiometric JPEG image
更新于2025-09-23 15:23:52
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Reinforcing effect of amine-functionalized and carboxylated porous graphene on toughness, thermal stability, and electrical conductivity of epoxy-based nanocomposites
摘要： Epoxy-based nanocomposites reinforced with nonfunctionalized porous graphene (NPG), carboxylated porous graphene (CNPG), and amine-functionalized porous graphene (ANPG) were investigated with regard to mechanical properties, thermal stability, and electrical conductivity. Nanomaterials were added to the epoxy matrix in varying contents of 0.5, 1, and 2 wt %. Generally, mechanical properties were improved as a result of introducing nanomaterials into the epoxy resin. However, the amelioration of toughness was only observed in functionalized NPGs/epoxy nanocomposites. Field emission scanning electron microscopy images showed that functionalized nanomaterials induced a rougher fracture surface compared to the neat epoxy. Dynamic mechanical analysis along with differential scanning calorimetry confirmed an increment in the glass-transition temperature (Tg) of the reinforced nanocomposites. Also, they proved that functionalization made the epoxy network tougher and more flexible. The electrical conductivity and thermal stability of the epoxy resin were also improved when loaded with nanomaterials.
关键词： toughness,electrical properties,thermal properties,nanocomposites
更新于2025-09-23 15:23:52
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Elastic, electronic and thermoelectric properties of Sr3MN (M?= Sb, Bi) under pressure
摘要： We have performed first-principles calculations to study the structural, elastic, electronic and thermoelectric properties of Sr3MN (M = Sb, Bi) under pressure. The optimized lattice parameters are in good agreement with the available experimental and theoretical measurements. Brittle to ductile transition occurs at 15 GPa and the hardness of both compounds decreases with the increase of pressure. The band gap slightly reduces with pressure and both compounds exhibit semiconducting nature for TB-mBJ potential. The density of states increases slightly at the Fermi level. The inclusion of the spin-orbit coupling effect reduces the band gap of Sr3BiN. The calculated Seebeck coefficient for Sr3SbN and Sr3BiN at 15 GPa and 600 K are 257 and 142 μV/K, respectively. The calculated lattice thermal conductivity of both compounds decreases with the increase of pressure, as phonon scattering increased. The predicted thermoelectric figure of merit (ZT) for Sr3SbN and Sr3BiN at 15 GPa and 600 K are 0.71 and 0.63, respectively. The obtained thermoelectric properties at high pressure making them suitable for thermoelectric device applications.
关键词： Lattice thermal conductivity,Pressure effect,Thermoelectric properties,Electronic properties,Elastic properties
更新于2025-09-23 15:23:52