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Fast neutron detectors with silicon photomultiplier readouts
摘要： This work summarizes a fast neutron detection performance of two different silicon photomultipliers from two manufacturers. The first SiPM (MAPD-3NK) from Zecotek Photonics consists of deeply buried cells with the active area 3.7x3.7 mm2. The second one (MPPC-S12572-010P) from Hamamatsu, however, consists of surface cell structure which the active area is 3x3 mm2. Both SiPMs have the same pixel density of 10000 mm-2. Both SiPMs coupled to Stilbene (5*5*5 mm3) and p-terphenyl (5*5*5 mm3) plastic scintillators were evaluated for detection ability of fast neutrons using a PuBe neutron source. Charge comparison and zero crossing neutron/gamma discrimination techniques were performed for these detectors and the results were compared. The obtained results prove a good fast neutron detection performance of the SiPMs which makes it possible to use these types of neutron detectors in fast neutron detection applications.
关键词： Pulse shape discrimination,Micropixel avalanche photodiode,Charge comparison,SiPM,MAPD,PSD,Zero crossing,Silicon photomultiplier
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - Tianjin, China (2019.8.4-2019.8.7)] 2019 IEEE International Conference on Mechatronics and Automation (ICMA) - The Application Research of Soft Starting Technology in Marine LED Lighting System
摘要： In this paper, for the problem that the LED lighting equipment affects the normal operation of the power supply equipment in ship due to the excessive starting current at the power-on moment, a soft-start technology scheme for LED power supply is proposed. The scheme is analyzed and compared in the marine LED lighting system. The application of technology solve the adverse effects of the LED lighting equipment on the power distribution system during the startup process, and conclude that the soft start technology has an improved effect on LED lighting system.
关键词： Inrush current,LED driver,instantaneous trip,zero-crossing trigger,soft start
更新于2025-09-16 10:30:52
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia) - Niigata (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Optimized Variable On-Time Control for LED Lighting Driver
摘要： This paper focus on how to implement variable on-time control to predictive boundary conduction mode boost PFC converter for driving LED lighting applications. Normally, the constant on-time control is implemented in predictive PFC converter, which leads to high THD of input line current. Varies of variable on-time control methods have been proposed to improve the THD of input line current. However, most of the proposed variable on-time calculation methods are too complex to be implemented in predictive control. In order to implement the variable on-time control to predictive control, a simple but very accurate variable on-time calculation method is applied. The optimized variable on-time control takes very short calculation time in DSP controller, hence it can be implemented in predictive control. The effectiveness of the proposed method which can reduce THD of line current is demonstrated on a 100 V input and 400 V/30 W output PFC prototype.
关键词： Predictive control,power factor correction,boundary conduction mode,zero-crossing point,total harmonic distortion.,power factor
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 3rd Optoelectronics Global Conference (OGC) - Shenzhen, China (2018.9.4-2018.9.7)] 2018 IEEE 3rd Optoelectronics Global Conference (OGC) - A Directional-Progressive Search Method for Infrared Small Target Detection
摘要： Infrared small target detection plays a key role in infrared precision guidance and infrared early-warning system. It has been a difficult problem for researchers to study on how to detect targets accurately at a long distance as early as possible. Most of the existing algorithms can detect small targets in simple backgrounds, but they would fail on the detection when the background clutters are chaotic and the signal to clutter ratio (SCR) is low. Therefore, we propose a new infrared small target detection method which called a directional-progressive search (DPS) method. Our method derives from a fact that a small target is an isotropic Gaussian distribution at a long distance, while clutters show different characteristics in different directions. Based on this difference, we decompose the original image into first-order sub-images with different directions by using a first-order directional derivative (FODD) filter. Then zero-crossing points are detected in each direction step by step to distinguish small targets and background clutters. After screening progressively, the positions where existing zero-crossing points in every sub- image can be confirmed as targets. Experimental results show that our method acquires higher detection rates and lower false alarm rates compared with other methods. At the same time, our method can still keep better performance under various complex backgrounds. The robustness of our method is strong.
关键词： facet model,target detection,infrared image,zero-crossing point
更新于2025-09-10 09:29:36
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Penetapan Kadar Hidrokortison Asetat dalam Sediaan Krim Mengandung Pengawet Nipagin secara Spektrofotometri Derivatif Orde Pertama
摘要： The simple and rapid spectrophotometric methods were developed for analysis of hydrocortisone acetate in cream pharmaceutical formulations containing nipagin as preservative. Concentration of hydrocortisone acetate was determined by measuring the first derivative absorption (ratio amplitudes) at 257.0 nm (zero crossing for nipagin). The calibration graphs were linear over the range of 4.0-40.0 ppm of hydrocortisone acetate (r= 0.9999). The limit of detection (LOD) and the limit of quantitation (LOQ) were found to be 0.9617 ppm and 3.2050 ppm, respectively. This method had good precision (repeatability and intermediate precision) with RSD < 2.0% where as the means of the recovery data (accuracy) were 102.03±0.14% and 100.23±0.69% for hydrocortisone acetate cream 1% and 2.5%, respectively. The proposed method was applied for the determination of hydrocortisone acetate in three out of four commercial cream formulations samples and the results of label claim were 102.93±0.22%, 108.48±0.19% and 106.67±0.35% for sample A, B and D, respectively. The result of brand C analysis showed to contain more than 110.0% of the labeled amount of hydrocortisone acetate, indicated there was additive other than nipagin in the cream basis to interfer with the hydrocortisone acetate measurements.
关键词： zero crossing,hydrocortisone acetate,cream formulations,derivative spectrophotometry,nipagin
更新于2025-09-04 15:30:14