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Laser based method for dynamic calibration of thermocouples
摘要： In dynamic temperature measurement, thermocouple sensors are widely used in harsh environments, and their dynamic characteristics directly affect the accuracy of dynamic temperature measurement. When the dynamic characteristics do not meet the requirements of dynamic test, dynamic errors will occur. In order to obtain the dynamic characteristics, it is necessary to calibrate the thermocouple dynamically. In this paper, a dynamic calibration system for the thermocouple was built. In the system, a high power laser was used to generate pulse temperature excitation. In order to realize the uniform heating, the laser beam homogenization system based on microlens array was studied and added to the dynamic calibration system. The homogenization system was designed and simulated, and the uniformity of the laser spot was measured after homogenization. A K-type butt-welded thermocouple was dynamically calibrated by using the dynamic calibration system. The dynamic mathematical model of the thermocouple was obtained by the system identification method, and the dynamic characteristics of the thermocouple were analyzed.
关键词： pulse excitation,laser,dynamic calibration,microlens array,thermocouple
更新于2025-09-23 15:21:01
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || SPECTROPHOTOMETRY/Diode Array ☆
摘要： Diode array spectrometry represents a particular approach for characterizing the result of the interaction between electromagnetic radiation and the sample, based on simultaneous measurement of light intensity over small spectral intervals having equal width. This is achieved through the following sequential stages, as schematically shown in Figs. 1 and 2D: a. interaction between the polychromatic beam and the sample; b. spatial dispersion of the transmitted (eventually reflected or emitted) radiation according to wavelength on multiple channels of equal widths, by means of a fixed optical element; c. imaging the dispersed radiation in a focal plane; and d. (quasi)simultaneous sampling of the dispersed radiation interval using photosensitive detectors, precisely positioned in the focal plane.
关键词： photodiode principle,Diode array spectrometry,concave diffraction gratings,spectrophotometry,instrumentation
更新于2025-09-23 15:21:01
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Molybdenum disulfide/silver/p-silicon nanowire heterostructure with enhanced photoelectrocatalytic activity for hydrogen evolution
摘要： Suitable semiconductor and its efficient coupling with catalysts is vital to hydrogen evolution reaction (HER). Herein, Ternary heterostructured MoS2/Ag/p-type silicon nanowires (SiNWs) array photocathode are constructed by a simple two-step method, where Ag is self-reduced on SiNWs via Galvanic Displacement method and MoS2 is subsequently loaded by direct thermal decomposition. Ag interfacial layer is introduced between Si and MoS2 to facilitate the charge transfer and suppress the recombination of photo-generated electron-hole pairs. MoS2/Ag/SiNWs exhibits an onset potential of 62 mV and photocurrent density of 50 mA cm?2 at ?1.0 VRHE, as well as good stability. Besides, MoS2/Ag/SiNWs is capable of generating 325.9 mL hydrogen per minute. The superior HER catalytic activity of MoS2/Ag/SiNWs is contributed to the improved charge transport at the solid–solid interfaces by virtue of Ag layer, allowing more electrons flow from SiNWs to MoS2 and thus effectively separating the photoelectrons and holes. This work demonstrates the potential of novel heterostructure for robust and efficient photoelectrochemical HER.
关键词： Heterostructure,Molybdenum disulfide,Hydrogen evolution,Ag layer,P-type silicon wires array
更新于2025-09-23 15:21:01
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A Photovoltaic Array Fault Diagnosis Method Considering the Photovoltaic Output Deviation Characteristics
摘要： There are a large number of photovoltaic (PV) arrays in large-scale PV power plants or regional distributed PV power plants, and the output of different arrays fluctuates with the external conditions. The deviation and evolution information of the array output are easily covered by the random fluctuations of the PV output, which makes the fault diagnosis of PV arrays difficult. In this paper, a fault diagnosis method based on the deviation characteristics of the PV array output is proposed. Based on the current of the PV array on the DC (direct current) side, the deviation characteristics of the PV array output under different arrays and time series are analyzed. Then, the deviation function is constructed to evaluate the output deviation of the PV array. Finally, the fault diagnosis of a PV array is realized by using the probabilistic neural network (PNN), and the effectiveness of the proposed method is verified. The main contributions of this paper are to propose the deviation function that can extract the fault characteristics of PV array and the fault diagnosis method just using the array current which can be easily applied in the PV plant.
关键词： photovoltaic array,deviation characteristics,fault diagnosis,probabilistic neural network
更新于2025-09-23 15:21:01
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Three-dimensional view of out-of-plane artifacts in photoacoustic imaging using a laser-integrated linear-transducer-array probe
摘要： Research on photoacoustic imaging (PAI) using a handheld integrated photoacoustic probe has been a recent focus of clinical translation of this imaging technique. One of the remaining challenges is the occurrence of out-of-plane artifacts (OPAs) in such a probe. Previously, we proposed a method to identify and remove OPAs by axially displacing the transducer array. Here we show that besides the benefit of removing OPAs from the imaging plane, the proposed method can provide a three-dimensional (3D) view of the OPAs. In this work, we present a 3D reconstruction method using axial transducer array displacement. By axially displacing the transducer array, out-of-plane absorbers can be three-dimensionally visualized at an elevation distance of up to the acquired imaging depth. Additionally, OPAs in the in-plane image are significantly reduced. We experimentally demonstrate the method with phantom and in vivo experiments using an integrated PAI probe. We also compare the method with elevational transducer array displacement and take into account the sensitivity of the transducer array in the 3D reconstruction.
关键词： Out-of-plane artifact,Three-dimensional reconstruction,Linear array,Beamforming
更新于2025-09-23 15:21:01
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A Si-based InP/InGaAs nanowire array photodetector operating at telecommunication wavelength
摘要： A Si-based vertical nanowire heterostructure array photodetector is designed and studied by a coupled three-dimensional optoelectronic simulation. Each nanowire is composed of an InP/In0.53Ga0.47As/InP axial p-i-n junction, which is designed to operate at telecommunication wavelengths. The results show that the absorption of the nanowire array strongly depends on the D/P ratio and nanowire diameter. By tuning the D/P ratio and diameter simultaneously, the peak absorption wavelength could be fixed at 1550 nm. Due to the light-trapping and light-concentrating properties, the nanowire array photodetector exhibits a remarkable responsivity beyond 0.8 A/W, several times higher than its thin film counterpart with the equivalent thickness. This work suggests that the III-V nanowire array is promising for high-performance Si-based photodetectors applied in optical telecommunication systems.
关键词： Nanowire array,Light-trapping,Optical communication,Si-based,InGaAs/InP
更新于2025-09-23 15:21:01
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Camera array-based digital image correlation for high-resolution strain measurement
摘要： Digital image correlation (DIC) is a well-known technique for non-contact, non-destructive, full-field deformation measurement in experimental solid mechanics. Although DIC has been widely used in science and engineering, the resolution of strain measurement with DIC is limited by imaging resolution and is much lower than that obtained with a strain gauge. To achieve a breakthrough in strain measurement using DIC, a camera array-based DIC method is proposed herein for high-resolution strain measurement. Twenty-five industrial cameras were assembled into a plane array, with each camera capturing a part of the specimen. A novel calibration-based image stitching method is proposed and was applied to these images and their corresponding displacement fields. The strain field was then calculated based on the stitched displacement fields. The use of the camera array greatly improved the measurement spatial resolution of DIC and made high-resolution strain measurement possible. Both static error analysis and four point-bending experiments were performed to demonstrate the feasibility and effectiveness of the proposed method, and a full-field strain resolution of 10 με was achieved.
关键词： displacement field stitching,camera array,Digital image correlation,image stitching,high-resolution strain measurement
更新于2025-09-23 15:21:01
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Experimental evaluation of silicon photonics transceiver operating at 120°C for 5G antenna array systems
摘要： The use of optical transceivers in antenna array system applications requires reliable operation at high temperature. The experimental characterisation of a silicon photonics transceiver operating in a harsh environment with temperatures up to 120°C is presented and discussed. The transceiver was placed inside a climatic chamber and it was fed by an external depolarised light source. The bit error rate was measured, and the impacts on transmission performances were analysed and discussed, including reliability aspects. The authors believe that silicon photonics transceivers with an optimised design and with improvements in the optical connector and fibre adhesive technology are suitable for this kind of applications.
关键词： silicon photonics,antenna array systems,transceiver,5G,high temperature operation
更新于2025-09-23 15:21:01
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Multibeam Monopulse SIW Slot Array Antenna
摘要： A multibeam slot array antenna is proposed in the 10-GHz band for a monopulse tracking system with resolution enhancement techniques. The antenna architecture combines a four-subarray SIW slot antenna, a multibeam-forming network of microstrip Rotman lens array, and a SIW comparator of four-quadrant monopulse technique. A method to form difference patterns in both E-plane and H-plane for mutibeams is presented, and the method can improve the accuracy of angle detection for all beams. The key point of the method is to compensate the phase difference caused by the beam deflection between two subarrays (quadrants) by constraining input delay lines of the Rotman lens array. To validate the proposed concepts, an antenna prototype is realized and measured. The experimental results demonstrate a scanning range of ±36° with -5 dB crossover level between two adjacent sum beams in the E-plane. The corresponding beams of difference pattern are generated in E-plane and H-plane via the monopulse comparator to enhance angle resolution. The multibeam monopulse system can achieve gains between 21.7 dBi and 23.5 dBi for all sum beams at the center frequency of 10 GHz. The lobe imbalances are less than 1.1 dB and null depths are lower than -16 dB for all difference patterns. This multibeam monopulse slot antenna can be applied in radar and communication systems requiring beam-scanning capabilities and target tracking.
关键词： slot array,Rotman lens,monopulse antenna,substrate integrated waveguide (SIW),Multibeam antenna
更新于2025-09-23 15:21:01
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Optimal Phase-Matching Strategy for Beam Scanning of Sub-Arrayed Phased Arrays
摘要： The design of phased array antennas generating two functional beams is here addressed. The first/primary beam is fixed and it is generated at the element level through the complex (amplitude and phase) weighting coefficients, while the second/secondary one is synthesized at the sub-array level by aggregating the array elements into non-overlapped clusters and using additional phase shifters at the clusters outputs. Towards this end, the sub-array configuration is determined by means of an ad-hoc iterative method aimed at reducing the unavoidable quantization lobes, while the synthesis of the sub-array phase coefficients, once the excitations at the element level have been set, is cast as a phase-matching problem whose analytic solution is optimal since it guarantees the minimum least-square error with respect to a reference phase distribution. A set of representative numerical results is reported and discussed to validate the proposed design approach and to point out its features and potentialities when addressing the synthesis of both pencil and shaped-beam power patterns.
关键词： Beam Scanning,Contiguous Partition Method,Sub-Arraying,Phase Matching,Active Electronically Scanned Array (AESA)
更新于2025-09-23 15:21:01