- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2019
- 2018
- 2017
- MPPT
- photovoltaic (PV) power systems
- Induction motor
- three-phase four switch inverter
- two-inductor boost converter
- Optical pattern
- Phase diagram
- Surfactants
- rad-hard
- converter
- Electrical Engineering and Automation
- Optoelectronic Information Science and Engineering
- Chemistry
- ETRI
- Inner Mongolia University
- Universiti Malaysia Terengganu
- Virginia Tech
- Indian Institute of Technology Indore
- Sree Buddha College of Engineering
- Devi Ahilya University
- GCoE, Amravati
- VPT, Inc.
- Beihang University
-
Low-loss and broadband non-volatile phase-change directional coupler switches
摘要： An optical equivalent of the field-programmable gate array (FPGA) is of great interest to large-scale photonic integrated circuits. Previous programmable photonic devices relying on the weak, volatile thermo-optic or electro-optic effect usually suffer from a large footprint and high energy consumption. Phase change materials (PCMs) offer a promising solution due to the large non-volatile change in the refractive index upon phase transition. However, the large optical loss in PCMs poses a serious problem. Here, by exploiting an asymmetric directional coupler design, we demonstrate non-volatile PCM-clad silicon photonic 1 × 2 and 2 × 2 switches with a low insertion loss of ~1 dB and a compact coupling length of ~30 μm while maintaining a small crosstalk less than ?10 dB over a bandwidth of 30 nm. The reported optical switches will function as the building blocks of the meshes in the optical FPGAs for applications such as optical interconnects, neuromorphic computing, quantum computing, and microwave photonics.
关键词： Silicon photonics,Non-volatile,Optical switches,Phase-change materials,Reconfigurable photonics,Integrated photonic devices
更新于2025-09-23 15:23:52
-
Linear and Nonlinear Optical Properties of Few-Layer Exfoliated SnSe Nanosheets
摘要： Monochalcogenides of group IV elements have been considered as phosphorene analogs due to their similar crystal and electronic structure. Here, few-layer SnSe nanosheets are synthesized by a sonication-assisted liquid phase exfoliation process and their linear and nonlinear optical properties are examined. The as-exfoliated few-layer (FL) SnSe demonstrates layer thickness from 2 to 10 nm and lateral size of 150 nm with high crystallinity. Optical measurement confirms the layer-number dependent bandgap, which is also corroborated by first-principle calculation. In addition, the FL SnSe shows a transition from saturable absorption to reverse saturable absorption with the increase of pumping power, and the nonlinear absorption is characterized by an ultrafast response time of picosecond scale. The nonlinear optical response in FL SnSe could be explained by defect-involved recombination of photogenerated carriers as well as the Auger scattering process, which is further enhanced by structural two-dimensionality.
关键词： nonlinear optics,phosphorene analogue,SnSe,liquid-phase exfoliation,2D semiconductors
更新于2025-09-23 15:23:52
-
Equation of state and structural characterization of Cu <sub/>4</sub> I <sub/>4</sub> {PPh <sub/>2</sub> (CH <sub/>2</sub> CH?=?CH <sub/>2</sub> )} <sub/>4</sub> under pressure
摘要： Combined high pressure single crystal X-ray diffraction experiments and ab initio simulations based on the density functional theory have been performed on a copper(I) iodide cluster formulated [Cu4I4{PPh2(CH2CH = CH2)}4] under high pressure up to 5 GPa. An exhaustive study of compressibility has been done by means of determination of isothermal equations of state and structural changes with pressure at 298 K taking advantage of the single crystal is more precise than powder X-ray diffraction for this type of experiments. It allows us to report the evidence of the existence of an isostructural phase transition of second order at 2.3 GPa not detected so far.
关键词： Copper iodide,high pressure,equation of state,phase transition
更新于2025-09-23 15:23:52
-
Low-phase noise 8.22 GHz GaN HEMT oscillator using a feedback multi-path transformer
摘要： This article designs a low-phase noise 8.22 GHz GaN high electron-mobility transistor (HEMT) oscillator in the WIN 0.25 μm GaN HEMT process. The oscillator uses a HEMT amplifier with a transformer as the feedback network. The transformer uses a 3-path secondary inductor and a single-path primary inductor. The GaN oscillator consumes the power 4.328 mW and generates a signal at 8.22 GHz with an output power ?11.35 dBm. At 1 MHz frequency offset from the carrier at 8.22 GHz the phase noise is ?120.82 dBc/Hz, the figure of merit of the proposed oscillator is ?192.76 dBc/Hz. The oscillator chip occupies an area of 2 × 1 mm2.
关键词： phase noise,3-path transformer,figure of merit,Q-factor,8.22 GHz GaN HEMT oscillator
更新于2025-09-23 15:23:52
-
The Structure of Phase-Change Chalcogenides and Their High-Pressure Behavior
摘要： Phase-change materials (PCMs) used in data storage devices have unique structural features and transition properties by thermal heating. Pressure, as another important thermodynamic tool, can also induce a series of interesting phase transitions in PCMs, accompanied by the altering of bonding nature and physical properties. Here, the structure transition as well as property change of prototypical phase-change material Ge–Sb–Te (GST) under hydrostatic pressure has been reviewed. The high-pressure behavior of some other relevant chalcogenides such as GeTe, Sb2Te3, and GeSe, is also discussed. The revealing of structure and property changes due to high pressure sheds light on the underlying physics of many fascinating properties of PCMs, and therefore it will have profound implications on various applications of phase change materials in memory and other fields.
关键词： high pressure,phase-change materials,Ge–Sb–Te,memory materials
更新于2025-09-23 15:23:52
-
[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Low-loss Loaded Line Phase Shifter for Radar Application in X Band
摘要： Losses in the phase shifters of phased arrays are one of the main limitations of these reconfigurable antennas. This contribution presents the design and measured results of variable phase shifters on triplicate suspended transmission lines in the microwave X-band for variable pointing radar applications. The antenna assembly remains passive and with a very low level of losses in the power distribution network and the phase shifters. PIN or varactor diodes are used to control the load on the transmission line. Each of these components has advantages and disadvantages that are discussed in the communication.
关键词： linear array,phase shifter,Pin diode,varactor,suspended strip
更新于2025-09-23 15:23:52
-
Development of a novel noninvasive system for measurement and imaging of the arterial phase oxygen density ratio in the retinal microcirculation
摘要： Purpose This study was conducted in order to develop a novel noninvasive system for measurement and imaging of the arterial oxygen density ratio (ODR) in the retinal microcirculation. Methods We developed a system composed of two digital cameras with two different filters, which were attached to a fundus camera capable of simultaneously obtaining two images. Actual measurements were performed on healthy volunteer eyes (n = 61). A new algorithm for ODR measurement and pixel-level imaging of erythrocytes was constructed from these data. The algorithm was based on the morphological closing operation and the line convergence index filter. For system calibration, we compared and verified the ODR values in arterioles and venules that were specified in advance for 56 eyes with reproducibility. In 10 additional volunteers, ODR measurements and imaging of the arterial phase in the retinal microcirculation corresponding to changes in oxygen saturation of the peripheral arteries at normal breathing and breath holding were performed. Results Estimation of incident light to erythrocytes and pixel-level ODR calculation were achieved using the algorithm. The mean ODR values of arterioles and venules were 0.77 ± 0.060 and 1.02 ± 0.067, respectively. It was possible to separate these regions, calibrate at the pixel level, and estimate the arterial phase. In each of the 10 volunteers, changes in the arterial phase ODR corresponding to changes in oxygen saturation of the peripheral arteries were observed before and after breath holding on ODR images. The mean ODR in 10 volunteers was increased by breath holding (p < 0.05). Conclusions We developed a basic system for arterial phase ODR measurement and imaging of the retinal microcirculation. With further validation and development, this may provide a useful tool for evaluating retinal oxygen metabolism in the retinal microcirculation.
关键词： Retinal microcirculation region,Arterial phase,Line convergence index filter,Oxygen density ratio,Morphological closing operation
更新于2025-09-23 15:23:52
-
Sensor Localization for Highly-Deformed Partially Calibrated Arrays with Moving Targets
摘要： In this letter, a sensor localization technique for highly-deformed partially calibrated arrays with multiple moving targets is proposed. The deformed array is divided into several subarrays. The first subarray is composed of the pre-calibrated sensors, while the sensors in the other subarrays are uncalibrated. The positions of the sensors are estimated from the phase differences between the pre-calibrated sensors and the uncalibrated sensors. The phase ambiguities caused by the highly-deformed sensor positions can be solved using the subspace orthogonality and the movement of multiple targets. Simulation results evaluate the performance of the proposed method, and the Cramer–Rao bounds are compared.
关键词： highly-deformed sensor array,partially calibrated sensor array,phase ambiguity,Sensor localization
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE Power & Energy Society General Meeting (PESGM) - Portland, OR, USA (2018.8.5-2018.8.10)] 2018 IEEE Power & Energy Society General Meeting (PESGM) - Experimental Determination of PV Inverter Response to Grid Phase Shift Events
摘要： With the continued growth of renewable energy resources which interface to the electric grid via inverters, the understanding of such devices becomes ever more important to the safe and reliable operation of the bulk power system. This work investigates the specific response of a utility-scale PV inverter to grid voltage phase shift-type disturbances which sometimes occur during grid fault events. The role of the PV inverter’s phase-locked-loop (PLL) is identified as important to modeling the response. Switching-level simulations of a utility-scale PV inverter with a modeled PLL show a characteristic response when phase shift disturbances require the PLL to track what appear as fast frequency changes. Additionally, in this work a full-scale laboratory testing was carried out using the Opal real time (RT) OP5142 real time simulator and a large grid simulator to create phase shift disturbances with a high degree of repeatability. A photovoltaic (PV) inverter was connected to a grid simulator, and phase shifts were instantaneously implemented on the simulated grid, the results of the currents were then obtained. The experimental results obtained were validated with simulation results obtained from MATLAB/Simulink.
关键词： frequency response,photovoltaics,phase-locked loops,harmonics,inverter,DER
更新于2025-09-23 15:23:52
-
A Novel Phytantriol-Based Lyotropic Liquid Crystalline Gel for Efficient Ophthalmic Delivery of Pilocarpine Nitrate
摘要： The purpose of this paper was to investigate the potential of liquid crystalline (LC) gels for ophthalmic delivery, so as to enhance the bioavailability of pilocarpine nitrate (PN). The gels were prepared by a vortex method using phytantriol and water (in the ratio of 73:27 w/w). Their inner structures were con?rmed by crossed polarized light microscopy, small-angle X-ray scattering, attenuated total re?ectance-Fourier transform infrared spectrum, and rheology. The in vitro release studies revealed that PN could keep sustained release from the gels over a period of 12 h. The ex vivo apparent permeability coef?cient of the gels demonstrated a 3.83-folds (P < 0.05) increase compared with that of eye drops. The corneal hydration levels of the gel maintained in the normal range of 79.46 ± 2.82%, hinting that the gel could be considered non-damaging and safe to the eyes. Furthermore, in vivo residence time evaluation suggested that a better retention performance of LC gel was observed in rabbit’s eyes compared to eye drops. In vivo ocular irritation study indicated that LC gel was nonirritant and might be suitable for various eye applications. In conclusion, LC gels might represent a potential ophthalmic delivery strategy to overcome the limitations of eye drops.
关键词： ophthalmic delivery,pilocarpine nitrate,cubic phase,liquid crystalline gel,phytantriol
更新于2025-09-23 15:23:52