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Structure and properties of layered perovskites Ba1-Ln Fe1-Co O3-δ (Ln = Pr, Sm, Gd)
摘要： A series of samples of overall composition Ba1-xLnxFe1-yCoyO3-δ (Ln = Pr, Sm, Gd) with x = 0.3-0.4; y = 0-0.5 were prepared by glycerin nitrate technique in air. The crystal structure of single-phase Ba1-xLnxFe1-yCoyO3-δ (Ln = Pr, Sm, Gd) determined by XRD was described as cubic (sp. gr. Pm3(cid:1)m). However, transmission electronic microscopy revealed that both Sm- and Gd-doped oxides possess tetragonal structure with 5-fold and 3-fold increased c parameter respectively. Oxygen content in the complex oxides has been determined in air over wide temperature range by means of thermogravimetry and iodometric titration. The change in oxygen content with temperature for the phases with five-layered ordering was significantly smaller than for the disordered phases.
关键词： oxygen nonstoichiometry,X-ray diffraction,oxide materials,transmission electron microscopy,crystal structure
更新于2025-09-23 15:22:29
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Modal transmission line theory of plane wave excited layered media with multiple conductive anisotropic sheets at the interfaces
摘要： A succinct and efficient transmission line formulation is presented for the analysis of plane wave excited planar multilayered uniaxial media comprising multiple conductive sheets at the interfaces. The conductive sheets may be anisotropic with a fully populated conductivity tensor, which results in the coupling the transverse-magnetic and transverse-electric waves. The transmission line formalism is thus extended to accommodate this hybrid mode of propagation. Three different algorithms for the solution of the transmission line network are developed and compared, including a numerically stable and efficient scattering matrix procedure. Numerical examples are included that validate the theoretical method.
关键词： Anisotropic conductive sheet,Terahertz,Transmission line network,Transition matrix,Graphene,Scattering matrix,Plane wave,Planar multilayer
更新于2025-09-23 15:22:29
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[IEEE IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - D.C., DC, USA (2018.10.21-2018.10.23)] IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - Simultaneous Wireless Information and GaN-Based Power Transfer Exploiting a Dual Frequency Band
摘要： A simultaneous wireless information and power transfer system employing separated frequency bands for energy and data, dubbed dual-band SWIPT, is investigated. Elementary circuit elements are optimized numerically. An experimental testbed based on a gallium nitride (GaN) full-bridge converter demonstrates data rates in excess of 450 kbps employing on-off keying in conjunction with a simple diode detector for data recovery.
关键词： Inductive power transmission,SWIPT,Data communication,Inductive charging,Frequency division multiplexing
更新于2025-09-23 15:22:29
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Contribution to the System Design of Contactless Energy Transfer Systems
摘要： In this contribution, a design procedure that is applicable to many kinds of wireless or contactless energy transfer systems is proposed. The design procedure is limited to near field wireless energy transfer systems in resonant operation. For this purpose, the input impedance and voltage transfer function of different natural frequencies are calculated analytically, and moreover, the behavior of the system is described. Following three issues lead to a readily applicable design procedure. First, the knowledge of the transfer functions. Secondly, the knowledge of basic magnetic properties and lastly, the known influence of harmonics according to rectifier and inverter. This design procedure is demonstrated with two hardware setups.
关键词： Inductive power transmission,power conversion harmonics,transfer functions,resonant inverters,inductive,charging
更新于2025-09-23 15:22:29
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Correlative infrared nanospectroscopy and transmission electron microscopy to investigate nanometric amyloid fibrils: prospects and challenges
摘要： Propagation of structural information through conformational changes in host-encoded amyloid proteins is at the root of many neurodegenerative disorders. Although important breakthroughs have been made in the field, fundamental issues like the 3D-structures of the fibrils involved in some of those disorders are still to be elucidated. To better characterise those nanometric fibrils, a broad range of techniques is currently available. Nevertheless none of them is able to perform direct chemical characterisation of single protein fibrils. In this work, we propose to investigate the structure of the C-terminal region of a bacterial protein called Hfq as a model amyloidogenic protein, using a correlative approach. The complementary techniques used are transmission electron microscopy and a newly developed infrared nanospectroscopy technique called AFM-IR. We introduce and discuss the strategy that we have implemented as well as the protocol, challenges and difficulties encountered during this study to characterise amyloid assemblies at the nearly single-molecule level.
关键词： correlative measurements,transmission electron microscopy,infrared nanospectroscopy,fibrils,Hfq,atomic force microscopy,Amyloid
更新于2025-09-23 15:22:29
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Polydimethylsiloxane: Optical properties from 191 to 1688?nm (0.735–6.491?eV) of the liquid material by spectroscopic ellipsometry
摘要： Polydimethylsiloxane (PDMS) is an important polymer with numerous applications. Herein, the authors report the optical function(s) of PDMS from 191 to 1688 nm as determined from reflection spectroscopic ellipsometry (SE) and transmission ultraviolet-visible data. Two commercial samples of liquid PDMS (PDMS700 and PDMS2000) with molecular weights of 700–1500 g/mol and 2000–3500 g/mol, respectively, were analyzed. Both samples were linear polymers terminated with silanol groups. The optical functions determined from the two materials were essentially identical. Both the reflection and transmission measurements obtained from these materials required special experimental considerations. For the reflection SE measurements, these included roughening (frosting) the inside of the vessel that held PDMS and the need to level the instrument instead of the samples. The transmission measurements were obtained via a dual cuvette approach that eliminated the effects of the cuvettes and their interfaces. In addition to analyzing the data from the individual samples, the SE data from the samples were considered together in a multisample analysis (MSA). Because both samples of PDMS were transparent over the measured wavelength range, and because of the relatively wide wavelength range considered, the optical functions here were fit with Sellmeier models. This produced a good fit for the MSA with a mean squared error value of 1.68. The optical functions obtained in this work agreed well with previously reported values. For example, for the MSA, the authors obtained the following nx values, where x is the wavelength in nanometers: n300 = 1.443, n500 = 1.407, and n1000 = 1.393.
关键词： spectroscopic ellipsometry,optical properties,Sellmeier,transmission,optical function,polydimethylsiloxane (PDMS)
更新于2025-09-23 15:22:29
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Voids in Kesterites and the Influence of Lamellae Preparation by Focused Ion Beam for Transmission Electron Microscopy Analyses
摘要： Kesterite solar cells based on Cu2 ZnSnS4 and Cu2 ZnSnSe4 (CZTSe) are potential future candidates to be used in thin-film solar cells. The technology still has to be developed to a great extent and for this to happen, high levels of confidence in the characterization methods are required, so that improvements can be made on solid interpretations. In this study, we show that the interpretations of one of the most used characterization techniques in kesterites, scanning transmission electron microscopy (STEM), might be affected by its specimen preparation when using focused ion beam (FIB). Using complementary measurements based on scanning electron microscopy and Raman scattering spectroscopy, compelling evidence shows that secondary phases of ZnSe mixed in the bulk of CZTSe are the likely cause of the appearance of voids in STEM lamellae. Sputtering simulations support this interpretation by showing that Zn in a ZnSe matrix is preferentially sputtered compared with any metal atom in a CZTSe matrix.
关键词： Cu2 ZnSn(S, Se)4 (CZTSSe),thin-film solar cells,transmission electron microscopy (TEM),focused ion beam (FIB),kesterite
更新于2025-09-23 15:22:29
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V-Defect and Dislocation Analysis in InGaN Multiple Quantum Wells on Patterned Sapphire Substrate
摘要： InGaN/GaN multiquantum well (MQW) structures have been grown on cone-shaped patterned sapphire substrates (CPSS) by metalorganic chemical vapor deposition (MOCVD). From the transmission electron microscopy (TEM) results, we found that most of the threading dislocations (TDs) in the trench region of the CPSS were bent by lateral growth mode. Also the staircase-like TDs were observed near the slant region of the cone pattern, they converged at the slope of the cone patterned region by staircase-upward propagation, which seems to effectively prevent TDs from vertical propagation in the trench region. The associated dislocation runs up into the overgrown GaN layer and MQW, and some (a+c) dislocations were shown to decompose inside the multi-quantum well, giving rise to a misfit segment in the c-plane and a V-shape defect. From cross-sectional TEM, we found that all V defects are not always connected with TDs at their bottom, some V defects are generated from the stacking mismatch boundaries induced by stacking faults which are formed within the MQW due to the strain relaxation.
关键词： V defects,Transmission electron microscopy (TEM),InGaN multi-quantum well (MQW),Threading dislocations (TDs)
更新于2025-09-23 15:22:29
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[IEEE 2018 25th International Conference "Mixed Design of Integrated Circuits and System" (MIXDES) - Gdynia, Poland (2018.6.21-2018.6.23)] 2018 25th International Conference "Mixed Design of Integrated Circuits and System" (MIXDES) - Optimization of Class-D Amplifier Output Stage for Piezoelectric Actuator Control
摘要： Design of a piezoelectric driver for a microelectromechanical actuator in a small form factor for laser telecommunications is introduced. The driver introduces a number of challenges due to its size and power limitations as a Microelectromechanical Systems (MEMS) actuator. Because of the small form factor, the driver must be integrated into the actuator itself, which limits its size and power. The efficiency of a linear amplifier becomes a major drawback due to the dissipated heat of only 20 W for the Laser Telecommunications Module (LTM), low efficiency of a linear amplifier becomes a major drawback due to the dissipated heat. Switching Class-E amplifiers provide exceptional efficiency compared to non-switching solutions at a price of high frequency harmonics, which allows for higher output power without additional heat dissipation. The efficiency, however, comes at a price of high frequency harmonics, which must be reduced by implementing a High-Energy-Efficiency Interference (HEEI) and Total Harmonic Distortion (THD). Driving a capacitive load, such as a piezoelectric actuator, at a high frequency with a Class-E amplifier requires a matching network to achieve the desired output power. The measurements were performed on a custom-made driver model for piezoelectric stack actuators with 270 V peak-to-peak voltage, 500 kHz switching frequency and a range of capacitive load from 2.1 nF to 20 nF.
关键词： Actuator,Driver,Amplifier,Distortion,LTM.2,Output Stage,SMPS,Class-E,Total,LTM,THD,MEMS,Harmonic,Transmission,Telecommunications,Laser,Module,High-Energy-Efficiency,HEEI,Interference,Piezoelectric,Microelectromechanical
更新于2025-09-23 15:22:29
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Fast Method to Optimize RF Bumper Transparency for Wide-Band Automotive Radar
摘要： This article describes novel methods to enhance the RF integration of wideband automotive radars. The first part of the paper is introducing the context and the considered scenario. Whereas the second part is focusing on two solutions to improve the radar integration in car chassis environment. The aim is to have good RF performances on wideband operation (76–81 GHz) and on a wide range of angle of incidence for the radar having wide field of view (e.g. Blind spot radar, Pedestrian detection,…).
关键词： transmission,metamaterial,reflection,radome,propagation,ACC radar
更新于2025-09-23 15:22:29