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Detection of Flare Multiperiodic Pulsations in Mid-ultraviolet Balmer Continuum, Lyl Hard X-Ray, and Radio Emissions Simultaneously 期刊论文 OAI收割
The Astrophysical Journal, 2021, 卷号: 921, 页码: 179
作者: HXMT

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收藏 | 浏览/下载：25/0 | 提交时间：2022/02/08

Solar flares Solar oscillations Solar ultraviolet emission Solar x-ray emission Solar radio emission 1496 1515 1533 1536 1522 Astrophysics - Solar and Stellar Astrophysics Abstract: Quasi-periodic pulsations (QPPs), which usually appear as temporal pulsations of the total flux, are frequently detected in the light curves of solar/stellar flares. In this study, we present the investigation of nonstationary QPPs with multiple periods during the impulsive phase of a powerful flare on 2017 September 6, which were simultaneously measured by the Hard X-ray Modulation Telescope (Insight-HXMT), as well as the ground-based BLENSW. The multiple periods, detected by applying a wavelet transform and Lomb-Scargle periodogram to the detrended light curves, are found to be ~20-55 s in the Ly`and mid-ultraviolet Balmer continuum emissions during the flare impulsive phase. Similar QPPs with multiple periods are also found in the hard X-ray emission and low-frequency radio emission. Our observations suggest that the flare QPPs could be related to nonthermal electrons accelerated by the repeated energy release process, i.e., triggering of repetitive magnetic reconnection, while the multiple periods might be modulated by the sausage oscillation of hot plasma loops. For the multiperiodic pulsations, other generation mechanisms could not be completely ruled out.

Timing analysis of Swift J1658.2-4242's outburst in 2018 with Insight-HXMT, NICER and AstroSat 期刊论文 OAI收割
Journal of High Energy Astrophysics, 2019, 卷号: 24, 页码: 30-40
作者: HXMT

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收藏 | 浏览/下载：56/0 | 提交时间：2022/02/08

Accretion accretion disks Black hole physics X-rays: binaries: Swift J1658.2-4242 Astrophysics - High Energy Astrophysical Phenomena Abstract: We present the observational results from a detailed timing analysis of the black hole candidate Swift J1658.2-4242 during its 2018 outburst with the observations of Hard X-ray Modulation Telescope (Insight-HXMT), Neutron Star Interior Composition Explorer (NICER) and AstroSat in 0.1-250 keV. The evolution of intensity, hardness and integrated fractional root mean square (rms) observed by Insight-HXMT and NICER are presented in this paper. Type-C quasi-periodic oscillations (QPOs) observed by NICER (0.8-3.5 Hz) and Insight-HXMT (1-1.6 Hz) are also reported in this work. The features of the QPOs are analyzed with an energy range of 0.5-50 keV. The relations between QPO frequency and other characteristics such as intensity, hardness and QPO rms are carefully studied. The timing and spectral properties indicate that Swift J1658.2-4242 is a black hole binary system. Besides, the rms spectra of the source calculated from the simultaneous observation of Insight-HXMT, NICER and AstroSat support the Lense-Thirring origin of the QPOs. The relation between QPO phase lag and the centroid frequency of Swift J1658.2-4242 reveals a near zero constant when < 4Hz and a soft phase lag at 6.68 Hz. This independence follows the same trend as the high inclination galactic black hole binaries such as MAXI J1659-152.

High beam quality all-solid-state 1053nm nd: Glass amplifier shaping by LCSLM at repetition frequency (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Optical, Electronic Materials and Applications 2012, OEMA 2012, May 25, 2012 - May 26, 2012, Chongqing, China
作者: Zhang X.; Qiu J.; Zhang X.; Zhang X.

收藏 | 浏览/下载：76/0 | 提交时间：2013/03/25

A laser amplifier of LD pumping Nd: glass with a high beam quality and stability the modulation degree near field is less than 1.23:1. (2012) Trans Tech Publications which amplifies nanosecond laser pulse Switzerland. has been developed in this paper. Under 1Hz repetition frequency when the flat top pulse of 3 ns width and 1 nJ energy is injected as the seed pulse the average output energy of the laser amplifier is 115.3 mJ with a net gain of 109 the energy dispersion degree of the outputting laser is no more than 2%

LED display panel grayscale modulation based on computer calculation (EI CONFERENCE) 会议论文 OAI收割
2012 International Applied Mechanics, Mechatronics Automation Symposium, IAMMAS 2012, September 7, 2012 - September 9, 2012, Shenyang, Liaoning, China
Wang R.-g.; Chang F.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

In order to improve the method of the LED display panel grayscale modulation a method based on computer calculation is proposed. First the development history and trends of the LED display panel are introduced. Second present the structure of the LED display panel and the existed modulation method. Simultaneously point out the ground for shortcomings of the existed method. Third describe the principle modulation method based on computer calculation detail from two steps which are the data signal transformation and the grayscale modulation. Forth describe the realization steps of this method in accordance with the third step. Finally this method is supplied in a LED display panel whose resolution is 320240. Experimental results show that this method is able to increase the grayscale from 14-bit to 16-bit and can enhance the display result of the LED display panel significantly. (2012) Trans Tech Publications Switzerland.

Space camera dynamic image quality measurement and evaluation (EI CONFERENCE) 会议论文 OAI收割
3rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2011, January 6, 2011 - January 7, 2011, Shanghai, China
作者: Zhang X.; Zhang X.; Zhang X.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

By using analysis of the infinity image of the space camera we intend to obtain the curve of the dynamic modulation transfer function. We extract the pixel gray values at the image edge which distribute as a knife-edge function and make differential calculation and Fourier transformation of it and then we can obtain the dynamic MTF curve of the optical system. The value of the curve at the Nyquist frequency is the most important parameter that reflects the image quality. We add push-scanning imaging and environmental effects to the static MTF of space camera and compare the MTF value with the dynamic MTF at Nyquist frequency. The comparison result can help us verify the accuracy of the calculating results and the feasibility of our method. (2011) Trans Tech Publications.

Design of reimaging F/1.0 long-wavelength infrared optical system (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Zhang X.; Zhang X.; Zhang X.

收藏 | 浏览/下载：36/0 | 提交时间：2013/03/25

A reimaging F/1.0 long-wavelength infrared optical system is proposed. The design has a flexible opto-mechanical layout. The design process is as follows. Firstly the catadioptric reimaging system consists of two reflecting mirrors and a relay lenses. Two reflecting mirrors make up of the first imaging system and are therefore free of chromatic aberrations while low dispersion lenses were used in the reimaging system so the optical system do not need achromatic design for a high image quality. Then to correct high-order aberrations resulting from large relative aperture more parameters need to be used with aspheric or diffractive surfaces due to modern optic technology development. Here aspheric is selected for easily manufacture. Finally the design is completed with the help of ZEMAX software. The effective focal length of the objective is 120mm and the field of view (FOV) is 4. The simulated final design shows adequate image quality and the modulation transfer function (MTF) is close to diffraction limit. The effect of the surrounding environmental temperature is analyzed using the concept of thermal defocusing and the thermal compensation is discussed. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

The application of diagnostic equipment in the Tokamak fusion reaction (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Optical Instruments and Technology: Optical Systems and Modern Optoelectronic Instruments, November 6, 2011 - November 9, 2011, Beijing, China
Zhang B.-S.; Chang J.; Gong X.-Z.; Gan J.-F.; Feng S.-L.

收藏 | 浏览/下载：17/0 | 提交时间：2013/03/25

This paper introduces the infrared optical system in the Tokamak fusion reaction device. In this optical system 3.the relay group lenses. This paper describes the decrease of the modulation transfer function (MTF) when the temperature changes and how to compensate the decrease of the MTF in order to maintain the image quality in a high level. As a result the traditional optical structure can't meet the requirements 2.the Cassegrain system the image quality of this optical system can reach the requirements when the temperature changes. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). because the length of the infrared optical system in the Tokamak is very long. The design of optical system in the detection facility includes three parts:1.the combination of the concave aspheric mirror and flat mirror

A brushless DC motor controller with current-loop control (EI CONFERENCE) 会议论文 OAI收割
2nd Annual Conference on Electrical and Control Engineering, ICECE 2011, September 16, 2011 - September 18, 2011, Yichang, China
Gao S.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

This paper presents a brushless DC motor controller with current loop control. The controller applies a complementary PWM modulation scheme to the power MOSFET. The current processor employed by the controller could detect the current flow through the motor windings accurately and convert the current to a voltage input to the error amplifier. The controller has 100% duty cycle high side conduction capability and real four quadrant torque control capability. It is able to implement a tight torque control for a DC brushless motor to satisfy the need of some servo system which calls for high bandwidth and raid dynamic response. 2011 IEEE.

Simulation and experiment of the static FTIR based on micro multi-step mirrors (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies, May 24, 2011 - May 26, 2011, Beijing, China
作者: Liang Z.-Z.; Zhang J.; Zhang J.; Zhang J.; Zhu W.-B.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

In recent years Fourier transform spectrometer (FTS) with small size and low mass is required in many applications with growing need for real-time and small platform spectral detection. In this paper a micro Fourier transform infrared spectrometer (FTIR) based on spatial modulation mode was designed. This spectrometer has the advantages of high stability and simplified configuration. It also promises optical path differences (OPD) with high precision as MOEMS technology is used in manufacturing the key components. The simulation and the experiments with regard to this FTIR configuration have been done. Firstly the diffraction effect of the micro multi-step mirrors (MMSMs) is studied. We discuss the influence to the reversed spectrum by different mirror widths and different diffraction distances. Secondly we simulate and analyze the influence of the source solid angle to the spectral resolution. Thirdly we set up the theoretical model of the collimation error which is mainly from the defocus of the optical system and analyze the result caused by the collimation error. Fourthly a new discrete Fourier transform arithmetic using least-squares cosines progression (LSCP) is proposed which can reconstruct the spectrum with nonuniform sampled signals. Finally the MMSMs are fabricated used the MOEMS technology and the structural parameters are tested. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Design and demonstration of micro multi-step mirrors and light source in micro FTIR (EI CONFERENCE) 会议论文 OAI收割
6th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2011, February 20, 2011 - February 23, 2011, Kaohsiung, Taiwan
Liang Z.; Fu J.; Feng C.; Liang J.

收藏 | 浏览/下载：42/0 | 提交时间：2013/03/25

To obtain high resolution high signal-to-noise ratio (SNR) high reliability and real time in wide spectral range we study the space modulation Micro Fourier Transform Spectrometer (FTS) based on multi-step mirrors covering the spectral range of 3-5m and 8-12 m in theory and experiment. The influences of spectrum reconstruction caused by the diffraction and extended light source in Fourier Transform Infrared Spectrometer (FTIR) are analyzed. A method to reduce the noises in spectrum reconstruction and the relationship between coherent intensity and solid angle of light source are discussed. An extended light source with suitable size is chosen considering the requirement of SNR and spectrum resolving power in the optical design. Furthermore the fabrication of micro multi-step mirrors which is the core part of FTS is investigated. Three methods for fabricating multi-step micro mirrors are demonstrated. 2011 IEEE.