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- low-temperature electronics
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- Bessel Function
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Effects of Skin Surface Temperature on Photoplethysmograph
摘要： Photoplethysmograph (PPG) has been widely used to investigate various cardiovascular conditions. Previous studies demonstrated effects of temperature of the measurement environment; however, an integrated evaluation has not been established in environments with gradual air temperature variation. The purpose of this study is to investigate variations and relationships of blood pressure (BP), PPG and cardiovascular parameters such as heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR), by changing skin surface temperature (SST). Local mild cooling and heating was conducted on 16 healthy subjects. The results showed that local SST changes affected Finometer blood pressures (Finger BP), PPG components and TPR, but not the oscillometric blood pressure (Central BP), HR, SV and CO, and indicated that temperature must be maintained and monitored to reliably evaluate cardiovascular conditions in temperature-varying environments.
关键词： skin surface temperature,Photoplethysmography,vasodilation,local cooling and heating,vasoconstriction,cardiovascular status
更新于2025-09-09 09:28:46
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Theoretical improvement of coupling parameters directional fiber coupler using Bessel function
摘要： We have investigated the optimum parameter to fabricate multi fiber of silica material for directional coupler based on fusion and elongation techniques. Coupling coefficient between the fibers was derived by using Bessel function. However, the fusion temperature was experimentally determined as function of elongation speed. Good performance of multi fiber coupler has been obtained for fabrication parameters of fusion temperature and elongation speed of 1350 oC and 125 μm/s respectively. The proposed coupling coefficient shows a better accuracy with empirical one for various coupling length. It is exponentially increased by reducing the distance between fibers. Finally, the microscopic analysis of coupling region deformation has shown that the silica material was well dispersed and distributed.
关键词： Bessel Function,Coupling Coefficient,Fusion temperature and Elongation speed
更新于2025-09-09 09:28:46
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Spray-Wall Impingement of Diesel-CNG Dual Fuel Jet using Schlieren Imaging Technique
摘要： Natural gas is a low cost fuel with high availability in nature. However, it cannot be used by itself in conventional diesel engines due to its low flame speed and high ignition temperature. The addition of a secondary fuel to enhance the mixture formation and combustion process facilitate its wider use as an alternative fuel. An experimental study was performed to investigate the diesel-CNG dual fuel jet-wall impingement. A constant volume optical chamber was designed to facilitate maximum optical access for the study of the jet-wall impingement at different injection pressures, temperatures and injector-wall distances. The bottom plate of the test rig was made of aluminum (piston material) and it was heated up to 500 K at ambient pressure. An injector driver was used to control the single-hole nozzle diesel injector combined with a natural gas injector. The injection timing of both injectors was synchronized with a camera trigger. The jet-wall impingement of diesel and diesel-CNG dual fuel jets was recorded with a high speed camera using Schlieren imaging technique and associated image processing software. The measurements of the jet radial penetration were higher in diesel-CNG dual fuel while the jet height travel along were higher in the case of diesel single fuel.
关键词： jet-wall impingement,wall temperature,injection pressure,diesel-CNG dual fuel,Schlieren imaging
更新于2025-09-09 09:28:46
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High-Temperature Cycle Durability of Superplastic Al-Zn Eutectoid Solder Joints with Stress Relaxation Characteristics for SiC Power Semiconductor Devices
摘要： We have developed a new high-temperature Al-Zn lead-free soldering process that utilizes superplasticity to realize SiC power devices with high-temperature cycle durability. The joining process consists of an Al-78wt.%Zn preparation being sandwiched by a SiC die and insulation substrate, an interfacial cleaning process at approximately 250-270oC, a heating stage to reach the solid-liquid coexisting temperature of 420-430oC, the ejection of low-melting-temperature β(Zn) from the joining area by press stress, and the transformation to a superplastic composition, i.e., Al-70 wt.% Zn at 270-310oC. Many lamellar phases that enable superplasticity can be formed in this microstructure. This solder joint composition was proven to have a better stress-relaxation effect than eutectic Al-95wt.%Zn, and the composition shows a much higher damping capability at the maximum operating temperature of SiC devices (200oC) than that of other joining candidates. The outstanding temperature cycle durability was verified in temperature cycle tests from -40oC to 300oC for 5000 cycles. This durability is due to the high-stress-relaxation effect from the superplasticity transformation realized by the lamellar structures in the Al-Zn alloy solder.
关键词： lamellar structure,damping capability,power semiconductor,SiC,superplasticity,temperature cycle test,Al-Zn eutectoid solder,lead-free solder,stress relaxation
更新于2025-09-09 09:28:46
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Persistent hydrophilicity for Titanium oxide (TiO2) thin films by Silicon oxide (SiO2) over nanolayers
摘要： SiO2 thin layers in thicknesses (1, 5, 10, 18 nm) on TiO2 thin layer in thickness 79 nm deposited by reactive RF sputtering technique. The deposited films were heat treated at temperatures (200, 400, 500, 600°C). The surface properties of thin films by atomic force microscopy (AFM), surface chemical composition by X-ray photoelectron spectroscopy (XPS) and self-cleaning effect in bi layers, were studied. In addition, enhanced hydrophilicity property in the films under the effect of annealed temperature and persistence without UV light illumination were evaluated.
关键词： Nanolayers,X-ray photoelectron spectroscopy (XPS),hydrophilicity,annealed temperature
更新于2025-09-09 09:28:46
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Structure Analysis and Ferroelectric Response of Bi <sub/>0.5</sub> Na <sub/>0.5</sub> TiO <sub/>3</sub> Nanopowder Synthesized by Sol–Gel Method
摘要： In this work, bismuth sodium titanate, Bi0(cid:2)5 ± xNa0(cid:2)5 ± y TiO3 (BNT, x(cid:3) y = ?0(cid:2)05–0.08) nanopowders were produced using the low-temperature sol–gel technique. The effects of de?cient and excess amounts of Bi and Na on BNT structure were systemically examined through X-ray powder diffraction (XRD), energy dispersive analysis (EDS) and scanning electron microscope (SEM). The optimized composition of the BNT nanopowder was pelletized and sintered at different temperatures (950 (cid:3)C–1150 (cid:3)C). Highly dense ceramics possessing pure perovskite phase was observed for the sample sintered at an optimum sintering temperature (1100 (cid:3)C). The ferroelectric properties were found to increase with an increase in sintering temperature up to 1100 (cid:3)C and then decrease. This study justi?es that Bi and Na non-stoichiometry (proper excess), processing and sintering temperatures play important role in the successful synthesis of BNT ceramics.
关键词： Nanopowders,Sol–Gel,Ferroelectric,Calcination Temperature
更新于2025-09-09 09:28:46
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Temperature-Dependent Domain Dynamics and Electrical Properties of Nd-doped Bi4Ti2.99Mn0.01O12 Thin Films in Fatigue Process
摘要： Bi4Ti2.99Mn0.01O12 (BTM) thin films with different ratio of neodymium (Nd) doping were prepared on Pt(111)/Ti/SiO2/Si(100) substrates through a sol-gel method. The effects of Nd doping on domain dynamics and temperature-dependent fatigue behaviors of BTM thin films were systematically studied. The polarization fatigues of BTM (not doped) and Bi3.5Nd0.5Ti2.99Mn0.01O12 (BNTM05) thin films first get better with the increasing temperature (T) from 300 to 350 K and then become worse from 350 to 400 K, while Bi3.15Nd0.85Ti2.99Mn0.01O12 (BNTM85) thin films show enhanced fatigue endurance from 300 to 400 K. It can be shown that the long-range diffusion of oxygen vacancies in BTM thin film happens more easily through the impedance spectra analysis with T from 300 to 475 K, which can be verified by a lower activation energies (0.13–0.14 eV) compared to those of BNTM05 and BNTM85 (0.17–0.21 eV). Using a temperature-dependent piezoresponse force microscopy (PFM), we have found more responsive domain fragments in Nd-substituted films. The microscopic domain evolution from 298 to 448 K was done to further explain that the domain wall unpinning effect has been enhanced with increasing T. The correlation between microscopic domain dynamics and macroscopic electrical properties clearly demonstrates the effects of charged domain wall in Nd-doped BTM thin films during the fatigue tests.
关键词： domain pinning,temperature-dependent fatigue,domain wall
更新于2025-09-09 09:28:46
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28.3: Development of High Performance TFT-LCD Module for Vehicle Display
摘要： The methods to achieve high performance vehicle displays are introduced. In order to achieve high contrast of wide viewing angle, the improvements include: a) the special function polarizer (POL), b) optical alignment process (OA), c) the optimal design of cell gap and d) a specific back light unit (BLU) film structure. Wide color gamut with high saturation is achieved by using the specially formulated light emitting diode (LED) with the specific color filter (CF). A special liquid crystal (LC) can help to come up to quick response time in wide temperature range.
关键词： wide color gamut with high saturation,vehicle display,quick response time in wide temperature range,high contrast of wide viewing angle
更新于2025-09-09 09:28:46
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Influence of Bi Substitution on the Microstructure and Dielectric Properties of Gd3Fe5O12 Ceramics
摘要： The exponential growth in microwave communications in recent years demands innovations and high yield microwave materials. Rare earth iron garnets are well known for their remarkable performance in microwave devices owing to their superior features. In this work we investigate the microstructure and dielectric properties of Bismuth substituted Gd3Fe5O12 ceramics prepared by the conventional solid state reaction route. The variation of lattice parameter, microstructure, permittivity, quality factor and temperature coef?cient of resonant frequency (sf) of Gadolinium Iron Garnet (GIG) with several concentrations of bismuth was investigated. The Bi3+ ion is effectively incorporated into Gadolinium Iron Garnet, due to which the sintering temperature is considerably reduced, and the densi?cation is improved signi?cantly. Moreover, with increase in Bi concentration, the dielectric constant of GIG also increases, while the quality factor is slightly reduced, which is correlated with the higher ionic polarizability of bismuth. At an appreciably low sintering temperature of 1050(cid:2)C, Gd2BiFe5O12 possess a porosity corrected relative permittivity value of 27.3 ± 0.2, unloaded quality factor (Qu 9 f) of 2990 ± 60 GHz (f = 7.3 GHz) and temperature coef?cient of resonant frequency + 60 ± 1 ppm/(cid:2)C.
关键词： microstructure,Low-temperature sintering,microwave dielectric properties,garnet structure
更新于2025-09-09 09:28:46
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Optimization of the liquid–liquid interfacial precipitation method for the synthesis of $$\hbox {C}_{60}$$C60 nanotubes
摘要： Tubular fullerene nanowhiskers called ‘fullerene nanotubes’ are composed of C60 fullerene molecules (C60 NTs) are synthesized at room temperature using the liquid–liquid interfacial precipitation method in the pyridine and isopropyl alcohol (IPA) system. The growth control of fullerene nanotubes is important for their chemical and physical properties as well as for their future applications. In the present study, we investigated the effect of light, water, solvent ratio and temperature on the synthesis of C60 nanotubes. A marked development in the yield of C60 NTs was achieved using dehydrated solvents, a solution with a volume ratio of 1:9 for pyridine: IPA, a growth temperature equal to 5?C and by illuminating the C60-pyridine solution with ultraviolet light (wavelength 302 nm) for 102 h. The synthesized fullerene nanotubes were characterized by different analytical techniques including Raman and Fourier transform infrared spectroscopy, optical microscopy, focussed ion beam scanning electron microscopy and transmission electron microscopy.
关键词： solution growth,liquid–liquid interfacial precipitation method,light,temperature,solvent,Fullerene nanotubes
更新于2025-09-09 09:28:46