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Humidity sensing characteristics of Sb2O3 thin films with transitional electrical behavior
摘要： The quest for smaller and more efficient humidity sensors is still on. Antimony trioxide thin films deposited by vacuum thermal evaporation onto heated glass substrates are analyzed as water vapor sensors, along with the study of their morpho-structural and electrical properties. Several substrate temperatures were set during the depositions, leading to films with significantly different electrical and humidity sensing features. Unusual increase of the electrical resistance of the films with temperature above 170 ?C was noticed, representing the intermediate stage between extrinsic and intrinsic conductivity. In the extrinsic conduction region, the activation energy decreases exponentially with the substrate temperature during the initial depositions. The alternative current (AC), i.e. the electrical frequency characteristics versus humidity were also studied, allowing for the identification of the conduction mechanism within the samples, which is most probably short range hopping of charge carriers through trap sites, influences by the changing grain size and remanent amorphous phase within the films.
关键词： Activation energy,Humidity sensitivity,Antimony trioxide,Thin films,Frequency characteristics
更新于2025-09-23 15:21:21
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Effects of waveform parameters on the breakdown characteristics of OIP subjected to impulse voltages and evaluation method for waveform equivalence
摘要： The impulse voltage wave invading a transformer is not the double exponential impulse wave (DEIW) specified by the IEC but a non-standard waveform with oscillation attenuation characteristics, and this fact leads to doubts about the scientificity and optimality of insulation coordination. A key solution for this issue is the establishment of an equivalent relationship between the measured non-standard impulse voltage wave and the DEIW. In this study, a test platform of multiparameter impulse voltage was set up. Then, the authors obtained the 50% breakdown voltage (U50%) of the oil-impregnated paper (OIP) for transformer under the bipolar oscillatory attenuated impulse wave (BOAIW) and the DEIW with different waveform parameters. The effects of waveform parameters on the breakdown characteristics of the OIP were finally revealed. On the basis of experimental data and several mathematical methods, the authors established the U50% prediction mathematical models for the OIP under the BOAIW and DEIW. Based on the prediction models and the microfluctuation characteristics of measured overvoltage's waveform parameters, the authors proposed a method for evaluating the waveform equivalence. The characteristics of voltage amplitude and change rate were regarded as the two key factors for the waveform equivalence of this method.
关键词： evaluation method,breakdown characteristics,waveform equivalence,impulse voltage,oil-impregnated paper
更新于2025-09-23 15:21:21
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - The Calculation of Energy Saving in use Light Management Systems
摘要： Light management systems are increasingly used in interior and exterior lighting. These systems offer many benefits for users of lighting. One of the most important advantages of these systems is the possibility of saving energy consumption for lighting purposes. Before deciding to use a lighting management system, it is worth knowing what value of savings energy this system will bring in specific case. The article present results of measurements basic light and electric parameters of LED luminaires with the possibility of controlling via DALI signal and obtained on base these measurements characteristic power control. Presented the method of calculating potential energy savings based on the received measurement results. Sources of differences between simulation calculations and real savings in using energy. The article present the differences between the evaluation of savings energy consumption simulation in the DIALUX program and real values. On the example of an existing lighting control system installed in sample room.
关键词： Light Management Systems,power control characteristics of LED luminaires,LED luminaires
更新于2025-09-23 15:21:21
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Role of Graphene-Doped Organic/Polymer Nanocomposites on the Electronic Properties of Schottky Junction Structures for Photocell Applications
摘要： In this study, the current–voltage characteristics of non-doped and distinct graphene (Gr)-doped polyvinyl alcohol (PVA) interlayers in metal/organic polymer semiconductor type Schottky junction structures (SJSs) were investigated on both forward and reverse biases under distinct levels of illumination. The distinct doping concentration ratios (1%, 3% and 7%) of the Gr added to the PVA interlayers were compared by taking into account the basic electrical parameters, such as saturation current (Io), ideality factor (n), barrier height (UBo), series (Rs) and shunt resistance (Rsh). The 7% Gr-doped structure displayed the lowest Io values at zero bias. Moreover, the results indicated that the 7% Gr-doped PVA decreased the n value but increased the UBo value compared with values associated with structures that have different doping concentrations. In terms of quality and reliability, the Rs and Rsh values of the SJSs were obtained using Ohm’s law and Cheung’s functions, and the 7% Gr-doped structure eventually displayed more uniformly distributed and lower Rs values and the highest Rsh values. Consequently, the 7% Gr-doped structure had better overall quality because of its superior electrical properties compared with structures that have other doping concentrations. Therefore, the 7% Gr-doped structure can be used as a photodiode in electronic devices.
关键词： photovoltaic,basic electronic properties,organic polymer nanocomposites,Graphene,I–V characteristics
更新于2025-09-23 15:21:21
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Monte Carlo Modeling of the Diodes with Lateral Resonant Tunneling Border
摘要： Diodes with resonant tunneling border (RTB) are studied as possible high speed and wide-band devices. The diodes represent planar two-terminal n+-n-n+-GaAs-based structures containing lateral active border as a AlGaAs/GaAs double barrier resonant tunneling structure connected to anode contact. The 2-D model of electron transport in the device is proposed. The analysis of the diodes operation was performed using ensemble Monte Carlo technique. Transfer matrix approach for simulation of tunneling transfer is applied. The influence of parameters of the diode structure such as a position of RTB, a composition of AlGaAs barriers and a material doping on current – voltage characteristics of diode has been investigated. strong influence of contact size and geometry on the diode characteristic. The aim of the work is to construct an effective numerical 2D model used to consider electron transport at high frequencies with taking into account hot-carrier effects in cases where the mean free path is comparable to the device dimensions and electron tunneling processes are in place. The basis of the proposed model is ensemble Monte Carlo method [4]. The other model elements are chosen by obtaining accurate physical results per reasonable time.
关键词： negative voltage current differential resistance,characteristics,heterojunction,quantum well,resonant tunneling border
更新于2025-09-23 15:21:21
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Optical Properties and Electronic Characteristics of Cerium in the Condensed State
摘要： The results of investigating optical properties of metallic cerium in the liquid and solid film state are presented. Optical constants were measured by the ellipsometric Beattie method in the range of 0.42–2.6 μm at ambient temperature. Based on the measured refractive indices and the absorption coefficients, spectra of light conductivity σ, reflectivity R, and characteristic loss function Im ε–1 were calculated. Based on experimental measurements in the IR region, electronic characteristics of liquid cerium and its polycrystalline film and their correlation with electrical conductivity have been determined.
关键词： optical properties,cerium,rare-earth metal,characteristics of conduction electrons,ellipsometry
更新于2025-09-23 15:21:21
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Electromagnetic Materials and Devices || Metal- and Dielectric-Loaded Waveguide: An Artificial Material for Tailoring the Waveguide Propagation Characteristics
摘要： In the present chapter a number of loaded structures are studied with circular cross-section to explore the deviation in their dispersion characteristics from their parent circular waveguide. The dielectric and/or metal loading to the waveguide tailors its dispersion characteristics. In general, the dielectric depresses and the metal elevates the dispersion characteristics from the characteristics of their parent circular waveguide. The axial periodicity results in periodic dispersion characteristics with a lower and an upper cut-off frequency (bandpass). However such a characteristic is not reported for the azimuthal periodic structures. The bandpass characteristic arises due to the shaping of the dispersion characteristics. Therefore the dispersion shaping is only possible with axial periodicity and not with the azimuthal periodicity. The sensitivity of the structure (geometry) parameters on the lower and upper cut-off frequencies, the extent of passband and the dispersion shaping are also included. In the axial periodic structures, the periodicity is found to be the most sensitive parameter for tailoring the dispersion characteristics and the disc-hole radius is the most sensitive parameter for shifting the dispersion characteristics over the frequency axis.
关键词： dispersion characteristics,dispersion shaping,metal and dielectric loading,disc-loaded circular waveguide,periodically loaded waveguide
更新于2025-09-23 15:21:01
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Effects of the Nozzle Tip Clogging and the Scanning Direction on the Deposition Process During Laser Metal Deposition of Alloy 718 Using a Four-Stream Discrete Nozzle
摘要： Depending on the configuration of the LMD system, the nozzle tilting is necessary to be able to manufacture parts with complex geometry. In these cases, the use of discrete coaxial nozzles is recommended. With this type of nozzle, the powder can clog the internal tips of the nozzle streams due to an inappropriate shape, size distribution, humidity or temperature conditions of the powder particles during the deposition process. This undesired effect can be an opportunity depending on the combination of the activated powder tips for coating complex surfaces when the geometry of the substrate acts as a barrier for the powder stream. This work presents for first time the effect of the scanning direction and the stream clogging on the deposition process in terms of powder efficiency, Material Deposition Rate (MDR) and clad geometry and dimensions, when Alloy 718 is deposited by LMD using a four-stream discrete coaxial nozzle.
关键词： Alloy 718,coatings,Laser metal deposition,geometrical characteristics,stream clogging,discrete nozzle
更新于2025-09-23 15:21:01
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Planar multifrequency mid-IR microwave-pumped lasers
摘要： The characteristics of planar repetitively pulsed diffusion-cooled HF, DF, HF – DF, Xe, and HF – DF – Xe(Kr) lasers pumped by a microwave discharge (2.45 GHz) are studied depending on the pump pulse duration (10 – 40 ms) and repletion rate (50 – 400 Hz), as well as on the composition and pressure of the working gas mixture (30 – 200 Torr) at low (to 0.6 L s–1) gas flow rates. It is demonstrated for the first time that a HF – DF – Xe gas-discharge laser may simultaneously operate as a HF – DF chemical molecular laser and a recombination laser based on xenon atom transitions and generate broadband (octave) radiation in the range 2.0 – 4.2 mm with an average output power of 43 mW and an efficiency of 0.9 %. With substitution of xenon for krypton, lasing in a HF – DF – Kr laser is obtained at wavelengths of 2.52 – 4.15 mm. Lasing in a HF – DF laser was achieved simultaneously in two spectral regions (2.7 – 2.9 and 3.6 – 4.2 mm) with an output power of ~50 mW. It is found that a decrease in the pump pulse duration with a simultaneous increase in the pulse repletion rate for retaining the average energy deposition leads to an increase in the average output power and efficiency of the laser. At low pulse repetition rates (50 – 100 Hz) and a low gas mixture flow rate, helium buffer gas can be effectively substituted for neon. Operation of the Xe laser was achieved in the spectral range 2.03 – 3.65 mm with an average output power of 580 Mw at a pump pulse duration of 20 ms, a pulse repetition rate to 10 kHz, and a maximum efficiency of 55 %. The obtained experimental results demonstrate the possibility of creating broadband HF – DF – Xe lasers emitting in the frequency range 2 – 4 mm with a desired ratio of intensities in different spectral ranges.
关键词： gas discharge,spectral characteristics,planar HF – DF – Xe laser,multifrequency lasing
更新于2025-09-23 15:21:01
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Numerical Investigation of Topological Edge States in a GaAs-Based Three-Dimensional Chiral Photonic Crystal
摘要： Massive expansion of wireless body area networks (WBANs) in the field of health monitoring applications has given rise to the generation of huge amount of biomedical data. Ensuring privacy and security of this very personal data serves as a major hurdle in the development of these systems. An effective and energy friendly authentication algorithm is, therefore, a necessary requirement for current WBANs. Conventional authentication algorithms are often implemented on higher levels of the Open System Interconnection model and require advanced software or major hardware upgradation. This paper investigates the implementation of a physical layer security algorithm as an alternative. The algorithm is based on the behavior fingerprint developed using the wireless channel characteristics. The usability of the algorithm is established through experimental results, which show that this authentication method is not only effective, but also very suitable for the energy-, resource-, and interface-limited WBAN medical applications.
关键词： Wireless body area networks,physical layer security,wireless channel characteristics,authentication
更新于2025-09-23 15:21:01