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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Investigations on electrical properties and correlations to electron and X-ray energies of pyroelectric LiTaO<inf>3</inf> and LiNbO<inf>3</inf>
摘要： The electrical properties of pyroelectric Lithium Tantalate (LiTaO3) and Lithium Niobate (LiNbO3) were investigated and compared to accessible X-ray energies by using the pyroelectric effect to generate X-rays. The capacitances of different crystals of varying sizes were measured and the resulting permittivities were calculated. A vacuum setup enabled a correlation to the maximum X-ray energies at a variable pressure. The presented results provide an overview of fundamental material properties and the effect on the generated difference of potential.
关键词： Lithium Niobate,pyroelectric crystal,vacuum electron source,X-ray spectrum,permittivity,X-ray energy,electron acceleration,electron emission,capacitance,Lithium Tantalate
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Self-focusing of electrons emitted by rectangular pyroelectric crystals: A study on geometrical conditions for optimized X-ray intensities
摘要： Pyroelectric crystals such as LiTaO3 or LiNbO3 offer the opportunity to produce X-rays with high energy and intensity. These pyroelectric X-ray sources may be used in XRF applications due to particular advantages. This report deals with systematic studies on the behavior of these crystals enabling an optimization of X-ray intensity. Furthermore, the focusing of electrons emitted by rectangular pyroelectric crystals has been studied.
关键词： Lithium Niobate,pyroelectric crystal,vacuum electron source,X-ray intensity,X-ray spectrum,focusing,electron acceleration,electron emission,Lithium Tantalate
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) - Analysis of Liquid Dielectrics by Photometric Instruments
摘要： The liquid dielectrics are used as an electrical insulation or as a medium for heat transfer in the power energy and high voltage devices such as transformers, HV cables or bushings. However dielectric degradations of these liquids are formed in time, most often caused by chemical pollution, thermal destruction or by the electric field influences. Especially electric strength and dissipation factor of insulating oil are affected by these negative influences. The result is the deterioration of devices isolation, which may cause the termination of devices life or even fire or explosion. To avoid loss of the device and further damage, the oil is periodically sampled from the device. The sample of oil is then analyzed, diagnosed and measured in the laboratory. Electrical parameters, mechanical and optical properties are the most common measured quantities. The optical analysis is usually very fast and reliable. There are many commercial analysis devices available on the market. However, none of them can measure all the parameters according to the standards with user settings. The design and realization of optical diagnostic equipment for analysis of liquid dielectrics according ISO 2049 and EN 60422 are the main contribution of this paper. Next monitored parameter is the spectral absorption and transparency of these liquids in the visible and UV spectrum. The proper function and accuracy of the measured methods will be verified in the Light laboratory and in the CVVOZEPower Laboratory in Brno University of Technology.
关键词： spectroradiometer,D-lamp,insulating oil,silicone oil,UV-vis,mineral oil,spectrophotometer,liquid dielectric,spectroscopy,spectrum
更新于2025-09-23 15:21:21
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Validation of spectrophotometric determination of chlorogenic acid in fermentation broth and fruits
摘要： A fast and accurate ultraviolet-visible (UV-vis) spectrophotometric method was established to determine the presence of chlorogenic acid (CGA) according to potassium ferricyanide-Fe (III) detection system. The reaction temperature and pH level greatly influenced the CGA absorption spectrum. Maximum UV-vis absorption wavelength occurred at 790 nm under the optimum conditions (at 25 ℃ and pH 7.0). The results of UV-vis were further assessed by comparing the results with those of high-performance liquid chromatography (HPLC). The proposed method showed a wide linear sensing range of 10.0-800.0 μg mL-1 (R2 = 0.9996) and a high degree of precision (%R.S.D. < 1.50) and recovery (%R.S.D. > 3.39). Results of CGA and HPLC methods correlated well with each other. The proposed accurate, rapid, sensitive, low-cost, and high-throughput method was successfully used to quantify CGA in fermentation broth and fruits (Mango). Therefore, it may be applied for measuring CGA in biological samples.
关键词： Ultraviolet-visible spectrum,Chlorogenic acid,biological samples,high-throughput,HPLC
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) - The Quasi-Fractal Microstrip Antenna
摘要： The results of study of integral characteristics of quasi-fractal circular-patch monopole antennas are presented. They are obtained by using the Finite Element Method (FEM). The spectral characteristics, matching characteristics with external circuits, the pattern characteristics are presented. The results obtained show that quasi-fractal monopole microstrip resonators can be successfully used to provide the necessary integral parameters and to form the required parameters of radiated fields.
关键词： fractal,disk monopole,pattern characteristic,microstrip,spectrum
更新于2025-09-23 15:21:21
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Output field squeezing in a weakly-driven dissipative quantum Rabi model
摘要： We present a generalized method to address the squeezing spectrum of the output field for a weakly-driven, dissipative quantum Rabi model and calculate it for a range of coupling strengths covering strong, ultra-strong and deep-strong coupling regimes. The need for a generalization arises because of the periodic time dependence of the correlation functions due to counterrotating terms in the quantum Rabi model. We here adopt time-averaging over such correlation functions to obtain the squeezing spectrum, which may also be relevant to experimental situations. We compare the calculated squeezing spectra with those of the driven dissipative Jaynes-Cummings model to illustrate the departure from the latter as the interaction strength increases. Our calculation shows that the overall squeezing increases with the interaction strength after optimization over the system-bath coupling strength and the driving field strength.
关键词： Quantum Rabi model,Jaynes-Cummings model,Spectrum of squeezing
更新于2025-09-23 15:21:21
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Study of Fano Resonance in the Core-Level Absorption Spectrum in Terms of Complex Spectral Analysis
摘要： We study theoretically the core absorption spectrum of an impurity embedded in a tight-binding chain in terms of complex spectral analysis. The absorption spectral pro?le associated with the resonance states in principle exhibits an asymmetric Fano-type structure, even without apparent multiple interference transition paths. The asymmetric Fano absorption pro?le is attributed to the complex-valued oscillator strength of the transition to the resonance state belonging to the extended Hilbert space. The boundary condition on the continuum causes a large energy dependence of the self-energy, so that it enhances the nonlinearity of the eigenvalue problem of the effective Hamiltonian, yielding several non-analytic resonance states. The optical transitions to these resonance states constitute the overall absorption spectrum structure.
关键词： Fano resonance,core-level absorption spectrum,complex spectral analysis,extended Hilbert space,resonance states
更新于2025-09-23 15:21:21
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The Infrared spectrum of very large (periodic) systems: global versus fragment strategies—the case of three defects in diamond
摘要： The calculation of the full vibrational spectrum (Infrared or Raman) of very large systems (say larger than one thousand atoms) is not only very expensive, but also of relatively low interest, as in many (most of the) cases only a subset of modes, well separated from the large, diffuse bands resulting from the superposition of thousands of peaks, is used for the spectroscopic characterization of the specific system under study. Here, a fragment strategy, consisting in computing and diagonalizing a reduced (in size) Hessian matrix centered around the zone of interest, is illustrated, and its accuracy and efficiency documented, by comparison with the full Hessian diagonalization (FHD) scheme. Three test cases are considered, showing different vibrational features. They are defects in diamond: the VN3 H defect (V stands for the vacancy), where the interesting point is the characterization of the bending and stretching modes of H, well separated from the large band resulting from the perturbation of the diamond manifold; the VH4 defect (four H atoms in the vacancy, with vibrational modes related to H appearing both at high and low wave numbers); and the I2N interstitial defect, with modes in which the N atoms are involved, appearing at wave numbers not far from the manifold of the perfect diamond modes. So the three cases, apparently similar, explore three different situations of interest for the fragment strategy: (1) localized modes very well separated from the large diamond continuous band ( VN3H); (2) modes at upper border of the large diamond continuous band ( I2N ): a case in which the modes of interest appear both as separated from and merged with the large continuous band ( VH4 ). It turns out that in all cases relatively small fragments, containing from 2 to 40 atoms, permit to reproduce with high accuracy (the difference with respect to the FHD being always smaller than 5 cm?1 for the wave numbers, and a few percent for the IR intensity) the spectral feature(s) of interest, at a computational cost that is only a small fraction of the one required by the FHD.
关键词： fragment strategy,vibrational modes,large systems,Infrared spectrum,diamond defects
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 21st Electronics Packaging Technology Conference (EPTC) - Singapore, Singapore (2019.12.4-2019.12.6)] 2019 IEEE 21st Electronics Packaging Technology Conference (EPTC) - An LTCC Based H-Antenna Aperture Coupled to an On-Chip Antenna for 2.4 GHz Long Range Transmitters
摘要： The latest trends in spectrum trading allow secondary users (SUs) to employ hybrid access models and exploit bandwidth employing either opportunistic spectrum access or exclusive spectrum access of vacant frequency bands (FBs) leased for exclusive usage. In this paper, the spectrum trading problem is addressed in an operational framework, where a primary spectrum owner (PSO) allocates specific FBs to a number of primary users (PUs) and at the same time allows SUs belonging to multiple service classes to operate opportunistically in a part of the spectrum primarily allocated to the PU operation. By offering exclusive bandwidth-price contracts to SUs in FBs, which are excluded from the PU access, the PSO expects additional revenue. In this framework, the PSO aims at maximizing its revenue through optimal contract design that considers the multiple SU service classes, about which the PSO may have at its disposal either complete or incomplete information. In the first case, it is proven that only one type of contract destined for the highest SU service class is profitable to the PSO. In the second case, two heuristic algorithms are proposed for the optimal contract design corresponding to offering a single contract or multiple contracts to various service classes. The simulation results for the complete and incomplete information cases have been examined with regard to the SU service classes and the number and transmission specifications of the PUs. The two proposed algorithms manage to address the incomplete information case and be close to the optimal values obtained when complete information is available. Finally, the social welfare, as the aggregate expected utility of all parties involved, is examined.
关键词： spectrum trading,cognitive radio,Dynamic spectrum access,contract theory,hybrid spectrum access
更新于2025-09-23 15:21:01
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Tunable spectrum resemblance of LED lights for improving the photosynthetic action of Chinese Cabbages
摘要： To increase efficiency, and reduce energy loss and waste, we propose to improve the photosynthetic action spectrum resemblance (SRPAS) of LED light with the absorption spectra of the fresh leaf, for accelerating the growth of Chinese Cabbages. Eight spectral LED lights were adopted to irradiate Chinese Cabbages under 150 μmol·m-2·s-1 for a 16 hd-1 photoperiod. Of these, under the irradiation of blue + broad red + more yellow (BRY2) light with high spectrum resemblance of 75%, the fresh weight and dry weight are 5.1times and 3.0 times, respectively, and the leaf area and leaf number are 1.7 times, as high as under the blue light. The results demonstrate that the optimized LED light can be presumed to have the highest spectrum resemblance (SRPAS) with the absorption spectra of Chinese Cabbages, and the highest energy-conversion efficiency. These conclusions may be of great benefit to further assess and find either an ideal light applied for plant growth or design of better light sources for growing different plants.
关键词： Absorption spectrum,Photosynthetic action spectrum resemblance,LED lighting,Growth and morphology,Chinese Cabbages
更新于2025-09-23 15:21:01