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Light-Field Imaging for Plasma Wind-Tunnel Application
摘要： Limited optical access and high apparatus complexity are the main challenges for true three-dimensional (3-D) measurements in high-enthalpy plasma flows. However, with the advent of plenoptic cameras, the one-shot and single-camera acquisition of light-field data has become possible, enabling the 3-D analysis of complex scenes with one single optical access and one single exposure. So far, this technique has mostly been applied to problems containing opaque objects or particle-loaded flows. In this paper, approaches to explore the potential of light-field analysis for the 3-D investigation of brightly luminous, high-velocity plasma flows are presented. Using gas flames from a solder torch, the feasibility of plenoptic imaging of optically thin scenes is shown. The complete structure of the flame is derived from a single exposure. The transition of this approach to plasma-flow visualization is shown with very first acquisitions of a plasma freejet, including spectral filters for the measurement of the atomic oxygen distribution.
关键词： high-enthalpy flows,light-field imaging,plasma wind tunnel,plenoptic camera,3-D reconstruction
更新于2025-09-23 15:22:29
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[IEEE 2019 IEEE 25th International Symposium for Design and Technology in Electronic Packaging (SIITME) - Cluj-Napoca, Romania (2019.10.23-2019.10.26)] 2019 IEEE 25th International Symposium for Design and Technology in Electronic Packaging (SIITME) - Analysis of positioning errors for LED
摘要： Conventional practice for transformer dissolved gas analysis (DGA) is to use concentrations of several fault gases, with or without total dissolved combustible gas, for evaluating apparent fault severity. We suggest a simpler approach based on the normalized energy intensity (NEI), a quantity related directly to fault energy dissipated within the transformer. DGA fault severity scoring based on NEI is shown to be sensitive to all IEC fault types and to be more responsive to shifts in the relative concentrations of the fault gases than scoring based on fault gas concentrations. Instead of eight or more gas concentration limits, NEI scoring requires only two or three limits that can be empirically derived to suit local requirements for any population of mineral-oil-filled power transformers.
关键词： fault energy,fault severity,Dissolved gas analysis (DGA),normalized energy intensity (NEI),transformer,enthalpy
更新于2025-09-23 15:21:01
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Modifying the thermomechanical properties of electrospun fibres of poly-vinyl cinnamate by photo-cross-linking
摘要： We explore the effects of cross-linking on some thermal and mechanical properties of polymer nanofibers of poly-vinyl cinnamate which were electro-spun from 1,2 dichloroethane. Scanning electron microscopy performed on the fibres revealed smooth fibres which were devoid of beading or ribbon-type features. When cross-linked, the Young’s moduli and glass transition temperatures of the fibres increase, owing to the formation of new covalent bonds which leads to higher overall binding energies. The glass transition temperatures increased by 20 K after 1 h of photo-polymerization while the Young’s modulus increased by 50% for the same exposure time. The glass transition temperatures as well as the heats of enthalpy indicate that a significant portion of cross-linking occurs within the first 10 min of exposure.
关键词： Photo-polymer,Young’s modulus,Enthalpy,Glass transition,Electro-spinning,Cross-linking
更新于2025-09-23 15:21:01
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Ultra-high sensitivity temperature sensor using a fiber loop mirror based on a water-filled asymmetric two-hole fiber
摘要： Conventional practice for transformer dissolved gas analysis (DGA) is to use concentrations of several fault gases, with or without total dissolved combustible gas, for evaluating apparent fault severity. We suggest a simpler approach based on the normalized energy intensity (NEI), a quantity related directly to fault energy dissipated within the transformer. DGA fault severity scoring based on NEI is shown to be sensitive to all IEC fault types and to be more responsive to shifts in the relative concentrations of the fault gases than scoring based on fault gas concentrations. Instead of eight or more gas concentration limits, NEI scoring requires only two or three limits that can be empirically derived to suit local requirements for any population of mineral-oil-filled power transformers.
关键词： enthalpy,Dissolved gas analysis (DGA),normalized energy intensity (NEI),fault energy,transformer,fault severity
更新于2025-09-23 15:19:57
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Nonconstant Enthalpy of thermosetting solid-solid Phase Change Materials Controlled by Light
摘要： Phase change materials (PCMs) based on the principle of latent heat thermal energy storage have been highly concerned by researchers and widely developed in various fields. However, for traditional PCMs, especially thermosetting solid-solid change materials (SSPCMs) which usually consist of crosslinking structure, the phase change enthalpy was fixed once the materials were constructed. To turn the constant enthalpy into adjustable one, we incorporated the light-sensitive methyl red (MR) groups into polyurethane-based SSPCMs. The MR-containing SSPCMs exhibit amplified enthalpy and increased melting temperature (Tm) after activated by UV light compared with the inactivated ones. UV treatment can promote the crystallization of the soft segment in polyurethane due to the light-induced isomerization of MR groups and visible light causes reverse effect of the activated samples that the enthalpy, Tm and crystallization get back to the original degree, which indicates the nonconstant enthalpy. A separation theory was proposed to explain the increased enthalpy and Tm caused by the cis configuration of MR groups.
关键词： nonconstant enthalpy,methyl red,separation theory,isomerization,irradiation
更新于2025-09-23 15:19:57
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Numerical prediction of solid-liquid front during laser melting of fused quartz
摘要： A 2-D transient model is explored for knowing the process of melting with laser in a Fused Quartz work piece. The work piece is irradiated with a single Gaussian laser pulse. The temporal variation is trapezoidal in nature. The laser source is considered as volumetric instead of surface laser source to match more closely with experiment. The convection and radiation heat losses are considered from the irradiated surface. By using the FVM (Finite Volume Method), the energy equation is discretized. The resulting algebraic equation is explained with the help of Tridiagonal matrix algorithm (TDMA) and it is to find the temperature field in the work piece. To capture the solid liquid front during the melting process the enthalpy-porosity method is used. With the help of available experimental results, the temperature field obtained is validated and a good agreement is found. The temperature field, the progress of the solid liquid front at different heating times and the melt depth is analysed to control the melting with laser intensity value.
关键词： Laser pulse,TDMA,Laser,Finite volume method,Enthalpy-porosity,Melting
更新于2025-09-23 15:19:57
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Detection of Volatile Organic Compounds in Exhaled Human Breath by Millimeter- Wave/Terahertz spectroscopy
摘要： Conventional practice for transformer dissolved gas analysis (DGA) is to use concentrations of several fault gases, with or without total dissolved combustible gas, for evaluating apparent fault severity. We suggest a simpler approach based on the normalized energy intensity (NEI), a quantity related directly to fault energy dissipated within the transformer. DGA fault severity scoring based on NEI is shown to be sensitive to all IEC fault types and to be more responsive to shifts in the relative concentrations of the fault gases than scoring based on fault gas concentrations. Instead of eight or more gas concentration limits, NEI scoring requires only two or three limits that can be empirically derived to suit local requirements for any population of mineral-oil-filled power transformers.
关键词： enthalpy,Dissolved gas analysis (DGA),normalized energy intensity (NEI),fault energy,transformer,fault severity
更新于2025-09-16 10:30:52
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Low-temperature synthesis of hydride semiconductor YH3?δ using Pt capped Y films and its chemical thermodynamics analysis
摘要： To decrease the temperature at which metallic yttrium (Y) reacts with H2 to form the semiconductor trihydride phase, we employed Pt capping layers as catalysts, and compared the result with those obtained when employing Pd, Ni, or their co-capping layers. It was found that Pt capping with 5 nm thickness makes trihydride phase majority when hydrogenated at 27°C, and allows us to obtain the trihydride phase with approximately 100% molar concentration when hydrogenated at 150 – 200°C. Chemical thermodynamics analysis of the experimental results reveals that both the enthalpy and entropy differences between pure states of trihydride phase and dyhydride phase with hydrogen vapor show monotonic hydrogenation temperature dependencies with their sign inversions at approximately the same temperature around 150°C, suggesting a particular thermodynamic mechanism specific to the hydrogen – yttrium system.
关键词： Platinum,Electron beam evaporation,Yttrium dihydride,Enthalpy,Yttrium trihydride,Yttrium,Entropy,Gibbs free energy
更新于2025-09-09 09:28:46
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Temperature and frequency effect on the electrical properties of bulk nickel phthalocyanine octacarboxylic acid (Ni-Pc(COOH)8)
摘要： The AC conductivity of nickel phthalocyanine octacarboxylic acid was investigated from 100 Hz to 1 MHz and temperature from 290 to 423 K. The AC conductivity was found to vary with frequency (σ(f)) and form two dispersion regions; the associated exponent factor “s” values were found to vary from 1.17 to 1.34 and from 0.42 to 0.67 (< 1). The value and temperature dependent of s are found in agreement with conduction mechanism models of large-polaron tunneling and the correlated barrier hopping, at the first and the second regions, respectively. The real and the imaginary parts of the dielectric constant were observed to decrease as the frequency increases indicating the pronounce contribution of low-frequency polarization mechanisms. Furthermore, the activation free energy ?F, enthalpy ?H, and entropy ?S of the sample were calculated as well.
关键词： enthalpy,polarization mechanisms,AC conductivity,activation free energy,dielectric constant,nickel phthalocyanine octacarboxylic acid,entropy
更新于2025-09-09 09:28:46
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Correlation between the structure and structural relaxation data for (GeSe2)y(Sb2Se3)1-y glasses
摘要： Combined calorimetric and structural study, employing the techniques of differential scanning calorimetry and Raman spectroscopy, was performed to describe the enthalpy relaxation processes in the (GeSe2)y(Sb2Se3)1-y chalcogenide glasses. The full glass forming compositional region (y = 0.3–0.9) was explored. The enthalpy relaxation was described in terms of the phenomenological Tool-Narayanaswamy-Moynihan model. Compositional evolution of the glass transition temperatures and relaxation activation energies was explained based on the changing average bond energies and overall interconnectivity of the glassy matrices. Resemblance between the activation energies of the relaxation processes and viscous flow was confirmed for all studied glasses. Non-linearity and non-exponentiality of the enthalpy relaxation were found to be invariant with composition. The structural relaxation kinetics as well as kinetic fragilities determined for the present (GeSe2)y(Sb2Se3)1-y glassy system were very similar to the results obtained earlier for the (GeS2)y(Sb2S3)1-y glasses, which can be attributed to the similarly constrained topology of the pseudo-binary compositional lines.
关键词： Enthalpy relaxation,Raman spectroscopy,TNM model,Ge-Sb-Se glasses,DSC
更新于2025-09-04 15:30:14