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- 实验方案
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High-Temperature Cycle Durability of Superplastic Al-Zn Eutectoid Solder Joints with Stress Relaxation Characteristics for SiC Power Semiconductor Devices
摘要： We have developed a new high-temperature Al-Zn lead-free soldering process that utilizes superplasticity to realize SiC power devices with high-temperature cycle durability. The joining process consists of an Al-78wt.%Zn preparation being sandwiched by a SiC die and insulation substrate, an interfacial cleaning process at approximately 250-270oC, a heating stage to reach the solid-liquid coexisting temperature of 420-430oC, the ejection of low-melting-temperature β(Zn) from the joining area by press stress, and the transformation to a superplastic composition, i.e., Al-70 wt.% Zn at 270-310oC. Many lamellar phases that enable superplasticity can be formed in this microstructure. This solder joint composition was proven to have a better stress-relaxation effect than eutectic Al-95wt.%Zn, and the composition shows a much higher damping capability at the maximum operating temperature of SiC devices (200oC) than that of other joining candidates. The outstanding temperature cycle durability was verified in temperature cycle tests from -40oC to 300oC for 5000 cycles. This durability is due to the high-stress-relaxation effect from the superplasticity transformation realized by the lamellar structures in the Al-Zn alloy solder.
关键词： lamellar structure,damping capability,power semiconductor,SiC,superplasticity,temperature cycle test,Al-Zn eutectoid solder,lead-free solder,stress relaxation
更新于2025-09-09 09:28:46
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[Institution of Engineering and Technology CSAA/IET International Conference on Aircraft Utility Systems (AUS 2018) - Guiyang, China (19-22 June 2018)] CSAA/IET International Conference on Aircraft Utility Systems (AUS 2018) - A New Automatic Tracking and Shooting Technique Used in Seat Ejection Test Based on Image Recognition
摘要： In rocket sled tests, a new automatic tracking technique based on image recognition is proposed to adapt to the development of intelligent technology. The automatic tracking system is mainly composed of tracking camera, shooting camera and technique adopted Camshift as the main algorithm, and at the same time designed and optimized the tracing algorithm of the key points such as the target capture of the rocket sled, the ejection seat coming out of the cabin, and man-seat separation, there by achieving the automatic tracking of the whole process of rocket sled ejection seat test. In addition, by conducting a simulation experiment with the angular velocity of 120°/s and the speed of 1.2 Ma, the feasibility of automatic tracking system servo control strategy is verified. Based on this automatic tracking technology, the design of automatic tracking test system for seat ejection test is being carried out.
关键词： Image recognition,Automatic tracking,Rocket sled test,Ejection seat
更新于2025-09-09 09:28:46
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Design, Development & Functional Validation of Magnets system in support of 42 GHz Gyrotron in India
摘要： A multi institutional initiative is underway towards the development of 42 GHz, 200 kW gyrotron system in India under the frame work of Department of Science and Technology, Government of India. Indigenous realization comprising of design, fabrication, prototypes and functional validations of an appropriate Magnet System is one of the primary technological objective of these initiatives. The 42 GHz gyrotron magnet system comprises of a warm gun magnet, a NbTi/Cu based high homogenous superconducting cavity magnet and three warm collector magnets. The superconducting cavity magnet has been housed inside a low loss cryostat. The magnet system has been designed in accordance with gyrotron physics and engineering considerations respecting highly homogenous spatial field profile as well as maintaining steep gradient as per the compression and velocity ratios between the emission and resonator regions. The designed magnet system further ensures the co-linearity of the magnetic axis with that of the beam axis with custom winding techniques apart from a smooth collection of beam with the collector magnet profiles. The designed magnets have been wound after several R & D validations. The superconducting magnet has been housed inside a low loss designed cryostat with in-built radial and axial alignment flexibilities to certain extent. The cryostat further houses liquid helium port, liquid nitrogen ports, current communication ports, ports for monitoring helium level and other instrumentations apart from over-pressure safety intensive burst disks etc. The entire magnet system comprising of warm and superconducting magnets has been installed and integrated in the Gyrotron test set-up. The magnet system has been aligned in both warm and when the superconducting cavity magnet is cold. The integrated geometric axes have been experimentally ensured as well as the field profiles have been measured with the magnets being charged. Under experimental conditions, all magnets including the superconducting magnet have been charged to their nominal values with appropriate protection measures against the quench. This is the first time in India that a gyrotron specific magnet system with superconducting magnet has been realized.
关键词： India,Superconducting Magnet,42 GHz Gyrotron,Gyrotron Test Set-up,Magnet System
更新于2025-09-09 09:28:46
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Energy correction for the BGO calorimeter of DAMPE using an electron beam
摘要： The DArk Matter Particle Explorer is an orbital indirect dark matter search experiment which measures the spectra of photons, electrons and positrons originating from deep space. The electromagnetic calorimeter (ECAL), made of bismuth germinate (BGO), is one of the key sub-detectors of DAMPE, and is designed for energy measurement with a large dynamic range from 5 GeV to 10 TeV. In this paper, methods for energy correction are discussed, in order to reconstruct the primary energy of the incident electrons. Di(cid:11)erent methods are chosen for the appropriate energy ranges. The correction results of Geant4 simulation and beam test data (at CERN) are presented.
关键词： beam test,energy correction,BGO ECAL,dark matter
更新于2025-09-09 09:28:46
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Optimal quantum-programmable projective measurement with linear optics
摘要： We present a scheme for a universal device which can be programed by quantum states to approximate a chosen projective measurement to a given precision. Our scheme can be viewed as an extension of the swap test to the instance where one state is supplied many times. As such, it has many potential applications given the variety of quantum information tasks which make use of the swap test. In particular, we show that our scheme is optimal for state discrimination under the one-sided error requirement, and optimally approximates any projective measurement. Furthermore, we propose a practical implementation of our scheme with passive linear optics, which involves a simple interferometer composed only of balanced beam splitters.
关键词： Hadamard interferometer,swap test,linear optics,state discrimination,quantum-programmable projective measurement
更新于2025-09-09 09:28:46
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Comparison of the Rayleigh and K-Distributions for Application in Incoherent Change Detection
摘要： The aim of this letter is to compare two incoherent change-detection algorithms for target detection in low-frequency ultrawideband (UWB) synthetic aperture radar (SAR) images. The considered UWB SAR operates in the frequency range from 20 to 90 MHz. Both approaches employ a likelihood ratio test according to the Neyman–Pearson criterion. First, the bivariate Rayleigh probability distribution is used to implement the likelihood ratio test function. This distribution is well known and has been used for change-detection algorithms in low-frequency UWB SAR with good results. Aiming to minimize the false alarm rate and taking into consideration that low-frequency UWB SAR images have high resolution compared to the transmitted wavelength, the second approach implements the test by using a bivariate K-distribution. This distribution has scale and shape parameters that can be used to adjust it to the data. No ?lter is applied to the data set images, and the results show that with a good statistical model, it is not needed to rely on ?ltering the data to decrease the number of false alarms. Therefore, we can have a better tradeoff between resolution and detection performance.
关键词： likelihood ratio test,synthetic aperture radar (SAR),Change detection
更新于2025-09-09 09:28:46
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Framework for Content-Based Image Identification with Standardized Multiview Features
摘要： Information identification with image data by means of low-level visual features has evolved as a challenging research domain. Conventional text-based mapping of image data has been gradually replaced by content-based techniques of image identification. Feature extraction from image content plays a crucial role in facilitating content-based detection processes. In this paper, the authors have proposed four different techniques for multiview feature extraction from images. The efficiency of extracted feature vectors for content-based image classification and retrieval is evaluated by means of fusion-based and data standardization–based techniques. It is observed that the latter surpasses the former. The proposed methods outclass state-of-the-art techniques for content-based image identification and show an average increase in precision of 17.71% and 22.78% for classification and retrieval, respectively. Three public datasets — Wang; Oliva and Torralba (OT-Scene); and Corel — are used for verification purposes. The research findings are statistically validated by conducting a paired t-test.
关键词： gray-level co-occurrence matrix,partial coefficients,feature extraction,morphological operator,classification,Local threshold,t-test,retrieval
更新于2025-09-04 15:30:14
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Modelling of XCO2 Surfaces Based on Flight Tests of TanSat Instruments
摘要： The TanSat carbon satellite is to be launched at the end of 2016. In order to verify the performance of its instruments, a ?ight test of TanSat instruments was conducted in Jilin Province in September, 2015. The ?ight test area covered a total area of about 11,000 km2 and the underlying surface cover included several lakes, forest land, grassland, wetland, farmland, a thermal power plant and numerous cities and villages. We modeled the column-average dry-air mole fraction of atmospheric carbon dioxide (XCO2) surface based on ?ight test data which measured the near- and short-wave infrared (NIR) re?ected solar radiation in the absorption bands at around 760 and 1610 nm. However, it is dif?cult to directly analyze the spatial distribution of XCO2 in the ?ight area using the limited ?ight test data and the approximate surface of XCO2, which was obtained by regression modeling, which is not very accurate either. We therefore used the high accuracy surface modeling (HASM) platform to ?ll the gaps where there is no information on XCO2 in the ?ight test area, which takes the approximate surface of XCO2 as its driving ?eld and the XCO2 observations retrieved from the ?ight test as its optimum control constraints. High accuracy surfaces of XCO2 were constructed with HASM based on the ?ight’s observations. The results showed that the mean XCO2 in the ?ight test area is about 400 ppm and that XCO2 over urban areas is much higher than in other places. Compared with OCO-2’s XCO2, the mean difference is 0.7 ppm and the standard deviation is 0.95 ppm. Therefore, the modelling of the XCO2 surface based on the ?ight test of the TanSat instruments fell within an expected and acceptable range.
关键词： XCO2 simulation,TanSat,XCO2 retrieval,HASM,?ight test
更新于2025-09-04 15:30:14
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Aluminum(III) triggered aggregation-induced emission of glutathione-capped copper nanoclusters as a fluorescent probe for creatinine
摘要： Glutathione-capped copper nanoclusters (CuNCs) are presented that display aggregation-induced emission (AIE). This feature was exploited for selective and sensitive quantification of creatinine (CRN) which is an important diagnostic parameter. In the presence of Al3+ ions, such CuNCs rapidly aggregate, and this induces enhanced a red emission. The AIE nature of CuNCs was proven via TEM and fluorimetry. On addition of CRN, the coordination between CRN and Al3+ ions led to the quenching of fluorescence due to weakening the AIE. The best fluorescence intensity was measured at excitation/emission peaks of 360/585 nm. Quenched fluorescence intensity showed a linear dependence on the concentrations of CRN in the range of 2.5–34 μgL?1 with a detection limit of 0.63 μgL?1. The sensing mechanism of probe for CRN detection is discussed. The probe was applied to the determination of CRN in spiked human serum samples and gave satisfactory results.
关键词： Nanosensor,Renal biomarker,Serum analysis,Fluorescent nanomaterials,Metal nanoclusters,Nanoprobe,Paired t-test,Fluorometry,Real sample analysis
更新于2025-09-04 15:30:14
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Effect of drain current on appearance probability and amplitude of random telegraph noise in low-noise CMOS image sensors
摘要： Random telegraph noise (RTN), which occurs in in-pixel source follower (SF) transistors, has become one of the most critical problems in high-sensitivity CMOS image sensors (CIS) because it is a limiting factor of dark random noise. In this paper, the behaviors of RTN toward changes in SF drain current conditions were analyzed using a low-noise array test circuit measurement system with a ?oor noise of 35 μVrms. In addition to statistical analysis by measuring a large number of transistors (18048 transistors), we also analyzed the behaviors of RTN parameters such as amplitude and time constants in the individual transistors. It is demonstrated that the appearance probability of RTN becomes small under a small drain current condition, although large-amplitude RTN tends to appear in a very small number of cells.
关键词： source follower (SF) transistors,drain current,CMOS image sensors (CIS),Random telegraph noise (RTN),low-noise array test circuit
更新于2025-09-04 15:30:14