- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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An ultrahigh spatial resolution radiation-imaging detector using 0.1 mm?×?0.1 mm pixelated GAGG plate combined with 1 mm channel size Si-PM array
摘要： Spatial resolution of a pixelated scintillator-based radiation-imaging detector is sometimes limited by the pixel size of the scintillators. We developed a small-size pixelated GAGG scintillator using a dicing method and combined it with a small channel-size Si-PM array for the development of an ultrahigh resolution radiation-imaging detector. The developed pixelated GAGG scintillator had a pixel size of 0.1 mm x 0.1 mm arranged in 0.15-mm separations. It was combined with a Si-PM array made of 1 mm x 1 mm channels to form a radiation-imaging detector. With the developed radiation imaging detectors, the 0.1 mm x 0.1 mm pixels could be resolved for Am-241 alpha particles (5.5 MeV). The spatial resolutions of this imaging detector were better than 0.31-mm FWHM for Am-241 alpha particles and Ca-45 (maximum energy: 0.24 MeV) beta particles. The spatial resolutions for Am-241 gamma photons (60 keV) and Cs-137 X-ray (~32 keV) were better than 0.6-mm FWHM. Separation of the images of alpha particles and gamma photons was possible using the scintillation decay time difference of GAGG between alpha particles and gamma photons. The developed ultrahigh spatial resolution pixelated GAGG radiation-imaging detector is promising for the imaging of alpha particles, beta particles, low-energy gamma photons and X-ray.
关键词： GAGG,ultrahigh spatial resolution,pulse-shape discrimination,pixelated,Si-PM array
更新于2025-09-04 15:30:14
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A two-step calibration method of lenslet-based light field cameras
摘要： The calibration of lenslet-based light field camera is the key issue to many applications, especially the three-dimensional shape measurement. In this paper, a two-step physically based calibration method is proposed, where every parameter is described with its own physical meaning. The parameters about the main lens of the light field camera are calibrated with the central sub-aperture image, and the parameters about the micro-lens array are calibrated with the epipolar images, subsequently. To improve the calibration result, the distortion correction of the main lens and a nonlinear optimization method are applied also. The calibration method is validated with a commercially available light field camera and compared to Dansereau’s calibration method. Typical RMS reprojection errors are 0.0017, 0.0032 mm for 30.0, 35.1 mm calibration grids.
关键词： Micro-lens array,Light field camera,Light field,Calibration,Main lens
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Saint Petersburg, Russia (2018.10.22-2018.10.23)] 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - S-Band Microstrip Bandpass Filter Design Based on New Approach to Coupling Coefficients Calculation
摘要： In this paper, a new approach to bandpass filter design, based on coupling coefficients calculation, introduced in [1], is experimentally verified. S-band (2.7 – 3.1 GHz bandwidth) microstrip bandpass filters of several four-resonator structures for pre-selectors of active phase array radar systems are designed, produced and measured. A conventional parallel-coupled filter is produced and measured for comparison. Measurement results confirm good performance of used approach.
关键词： S-band,open-loop resonator,bandpass filter,microstrip,coupled resonators,active phase array radar,pre-selector
更新于2025-09-04 15:30:14
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[IEEE 2018 2nd International Conference on Trends in Electronics and Informatics (ICOEI) - Tirunelveli, India (2018.5.11-2018.5.12)] 2018 2nd International Conference on Trends in Electronics and Informatics (ICOEI) - Analysis of Active and Passive Method for Islanding Detection of 3-Phase Grid Connected PV System
摘要： The purpose of this paper is to detect islanding condition in three phase grid connected PV system by using islanding detection method. PV system has more momentum in power sector due to market deregulations and environmental issues. Islanding occurs when a portion of the distribution system becomes electrically isolate from the main generation and grid meet continues power by PV array system. so, it is very important requirement to interconnect a solar system to power grid and their the capability of the PV system to detect islanding detection. Anti-islanding methods generally can be classified into four major groups, which include passive methods, and communication base methods. Also, this paper is offer knowledge about PV array, DC-DC converter, voltage source converter in grid connected photovoltaic systems and explain one passive method and one active method for islanding detection of three phase grid connected PV system with MATLAB simulations and results.
关键词： boost converter,voltage source converter,PV array,islanding detection
更新于2025-09-04 15:30:14
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Analysis and Design of High Frequency 1-D CMUT Imaging Arrays in Non-collapsed Mode
摘要： High frequency ultrasound imaging arrays are important for a broad range of applications, from small animal imaging to photoacoustics. CMUT arrays are particularly attractive for these applications as low noise receiver electronics can be integrated for an overall improved performance. In this paper we present a comprehensive analysis of high frequency CMUT arrays based on an experimentally verified CMUT array simulation tool. The results obtained on an example, a 40 MHz 1-D CMUT array for intravascular imaging, are used to obtain key design insights and tradeoffs for receive only and pulse-echo imaging. For the receiver side, thermal mechanical current noise, plane wave pressure sensitivity, and pressure noise spectrum are extracted from simulations. Using these parameters, we find that the receiver performance of CMUT arrays can be close to an ideal piston, independent of gap thickness and applied DC bias, when coupled to low noise electronics with arrays utilizing smaller membranes performing better. For pulse-echo imaging, thermal mechanical current noise limited SNR is observed to be dependent on the maximum available voltage and gap thickness. In terms of bandwidth, we find that Bragg resonance of the array, related to the fill factor, is a significant determinant of the high frequency limit and the fluid loaded single membrane resonance determines the lower limit. Based on these results, we present design guidelines requiring only fluid loaded single membrane simulations and membrane pitch to achieve a desired pulse-echo response. We also provide a design example and discuss limitations of the approach.
关键词： CMUT,Bragg’s resonance,CMUT design,High frequency arrays,Phased array,Photoacoustic receiver
更新于2025-09-04 15:30:14
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Compact Dual-Band Coupler for Vehicular Beam-Forming Array
摘要： A novel kind of compact dual-band quadrature patch coupler for vehicular beam-forming array is proposed for the first time in this paper. To keep the performance of the first operating frequency 2.4 GHz (for Bluetooth Low Energy (BLE)) and generate the second operating frequency 5.9 GHz (for Dedicated Short Range Communications (DSRC)) simultaneously, complementary triangular split resonant rings (CTSRRs) and splitting gaps are employed to improve the performance of this new coupler; final size of the proposed coupler is 0.24???? (for 2.4 GHz). To validate the performance and design method of the coupler this paper proposed, a 3D model is constructed and optimized with ANSOFT HFSS firstly and then a coupler prototype is fabricated and measured. The measured results show that the amplitude unbalance (AU) is 0.54 dB and 0.44 dB for 2.4 GHz and 5.9 GHz, respectively, and the corresponding phase unbalance (PU) is 93.5 and 92 degrees, respectively.
关键词： ANSOFT HFSS,vehicular beam-forming array,CTSRRs,compact dual-band coupler
更新于2025-09-04 15:30:14
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On the instantaneous dose rate and angular dependence of monolithic silicon array detectors
摘要： The use of small radiation fields characterized by very steep dose gradients is common in modulated arc x-ray radiotherapy. Dosimeters for quality assurance applications would ideally have sensitive volumes relatively small with respect to the field, along with negligible instantaneous dose rate and angular dependence. Silicon-based dosimeters can be fabricated with sensitive volumes < 100 μm across, provide a stable and near energy-independent response in megavoltage photon beams, along with a good linearity with accumulated dose and real-time read-out. However, their sensitivity is instantaneous dose rate and angular dependent. Monolithic silicon array detectors with sufficiently small sensitive volumes and pitch are suitable for high-resolution 2D dose mapping in radiation fields with steep dose gradients. The Octa is a 2D monolithic silicon array detector. It has 512 diode-sensitive volumes arranged with a sub-millimeter pitch. The physical characteristics of the substrate on which it is based, in terms of resistivity and defects concentration, strongly affect its performance. We report on the experimental characterization of two versions of the Octa, manufactured on a bulk and on an epitaxial substrate respectively. Their performance is compared and discussed in terms of their instantaneous dose rate and angular dependence in the context of quality assurance applications in small radiation fields delivered with modulated arc radiotherapy.
关键词： small-field dosimetry,angular dependence,instantaneous dose rate dependence,2D monolithic silicon array detector
更新于2025-09-04 15:30:14
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[IEEE 2018 26th European Signal Processing Conference (EUSIPCO) - Roma, Italy (2018.9.3-2018.9.7)] 2018 26th European Signal Processing Conference (EUSIPCO) - Light - fields of Circular Camera Arrays
摘要： The ray structure and sampling properties of different light-field representations inherently determine their use-cases. Currently prevalent linear data structures do not allow for joint processing of light-fields captured from multiple sides of a scene. In this paper, we review and highlight the differences in capturing and reconstruction between light-fields captured with linear and circular camera arrays. We also examine and improve the processing of light-fields captured with circular camera arrays with a focus on their use in reconstructing dense light-fields, by proposing a new resampling technique for circular light-fields. The proposed circular epipolar light-field structure creates a simple sinusoidal relation between the objects of the scene and their curves in the epipolar image, opening the way of efficient reconstruction of circular light-fields.
关键词： camera array,capture configuration,light-field
更新于2025-09-04 15:30:14
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - A Circularly Polarized Circular Antenna Array for Satellite TV Reception
摘要： This paper proposes a novel design of a wideband compact circularly polarized circular antenna array for satellite TV reception. The circular array is based on a wideband circularly polarized spiral antenna element which has excellent impedance matching (VSWR ≤ 1.5) and axial ratio bandwidths for the satellite-to-ground downlink at Ku-band from 11.7-12.7 GHz. A 16-element circular sub-array is presented with a fixed 23° electronically steered beam upwards which is appropriate for Astra satellite communications in the UK. Furthermore, circular sub-arrays with different numbers of elements (8, 16, 24, 32 and, 40) are also studied. It is shown that the circular antenna array is particularly suitable for satellite TV reception while being vertically mounted on a wall because of its low profile, broadband and electronically steered beam.
关键词： Circular array,electronic steering,satellite communications,circularly-polarized antenna,spiral antenna
更新于2025-09-04 15:30:14
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Overview of Naval Multifunction RF Systems
摘要： Multifunction radio frequency (RF) systems employ active electronically scanned array technology to consolidate radar, communications, electronic attack and electronic support. This paper presents key characteristics of multifunction RF (MFRF) systems for naval platforms, together with advantages and drawbacks relative to individual RF systems. Requirements for RF functions are provided, and design considerations for naval MFRF systems are discussed. Future research topics in MFRF systems are presented: MFRF system design, which is constrained by hardware technology; and resource management among multiple RF functions, which builds on previous results in radar resource management.
关键词： radar,radio frequency,electronic support,electronic attack,Naval platforms,communications,active electronically scanned array
更新于2025-09-04 15:30:14