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On the Terrestrial Gamma Ray Flashes Preceding Narrow Bipolar Events 期刊论文 OAI收割
Geophysical Research Letters, 2021, 卷号: 48, 页码: e92160
作者: HXMT

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low frequency magnetic sferics narrow bipolar events (NBEs) relativistic feedback mechanism Terrestrial Gamma ray Flashes (TGFs) Abstract: Narrow bipolar events (NBEs) are occasionally reported to occur within a few ms after Terrestrial Gamma ray Flashes (TGFs), while the formation mechanism remains mysterious partially due to the lack of sufficient observations. Here, nine more TGFs of this scenario are reported with concurrent LF sferics and lightning location data. The gamma ray production in these TGFs preceded the occurrence of NBEs by a minimum of 60 µs up to 13.5 ms, and no other fast leader discharge was found within 20 ms before the TGF. The TGF preceded positive NBEs occurred at altitudes of 8.6-11 km in thunderstorms, likely in the high electric field (E field) region of lightning initiation. The analyses show that the NBE preceding TGFs bear harder energy spectrum with larger proportion of high energy photons than EIP related TGFs produced in association with lightning leader. Our findings support the relativistic feedback mechanism of gamma ray generation in the large scale thunderstorm E field.

Comparison of simulated backgrounds with in-orbit observations for HE, ME, and LE onboard Insight-HXMT 期刊论文 OAI收割
Astrophysics and Space Science, 2020, 卷号: 365, 页码: 158
作者: HXMT

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Insight-HXMT Geant4 simulation Background observation Astrophysics - Instrumentation and Methods for Astrophysics Abstract: Insight-HXMT, the first X-ray astronomical satellite in China, aims to reveal new sources in the Galaxy and to study fundamental physics of X-ray binaries from 1 to 250 keV. It has three collimated telescopes, the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME), and the Low Energy X-ray telescope (LE). Before the launch, in-orbit backgrounds of these three telescopes had been estimated through Geant4 simulation, in order to investigate the instrument performance and the achievement of scientific goals. In this work, these simulated backgrounds are compared with in-orbit observations. Good agreements are shown for all three telescopes. For HE, (1) the deviation of the simulated background rate after two years of operation in space is 5 % from the observation (2) the total background spectrum and the relative abundance of the 67 keV line show long-term increases both in simulations and observations. For ME, (1) the deviation of simulated background rate is within 15 % from the observation, and (2) there are no obvious long-term increase features in the background spectra of simulations and observations. For LE, the background level given by simulations is also consistent with observations. The consistencies of these comparisons validate that the Insight-HXMT mass model, i.e., space environment components and models adopted, physics processes selected, and detector constructions built, is reasonable. However, the line features at 7.5 and 8.0 keV, which are obvious in the observed spectra of LE, are not evident in simulations. This might result from uncertainties in the LE constructions.

OUTPATIENT CAPACITY ALLOCATION CONSIDERING ADDING CAPACITY TO MATCH HIGH PATIENT DEMAND 期刊论文 OAI收割
JOURNAL OF SYSTEMS SCIENCE AND SYSTEMS ENGINEERING, 2017, 卷号: 26, 期号: 4, 页码: 487-516
作者: Jiang Bowen; Tang Jiafu; Yan Chongjun

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ACCESS SCHEDULING SYSTEMS NO-SHOWS HEALTH-CARE REVENUE MANAGEMENT OVERBOOKING MODEL SERVICE OPTIMIZATION SIMULATION CLINICS SINGLE Appointment adding capacity policy no-show high demand two-tier enumeration

Laser cleaning of neutral attenuator plate based on low power laser diode (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Energy, Environment and Sustainable Development, EESD 2012, October 12, 2012 - October 14, 2012, Jilin, China
作者: Chen Y.; Li L.

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Laser cleaning is a non-contact green and environmental cleaning method which can effectively remove particulate contaminations of sizes as small as 0.1 m without damage to the optics. But most laser cleaning devices are large and heavy also expensive due to using large lasers such as CO2 laser YAG Laser etc. In this work a low power LD was tried to clean fingerprint and dust contaminated on the surface of the attenuator glasses plates. In the laser cleaning experiment with low power diode the fingerprint grease can be efficient to be cleaned but there is no evident effect for cleaning inorganic dust. The cleaning different degree of fingerprint contaminations was investigated at the variable laser parameters including laser power and irradiation time. An optical microscope was used to analyze the cleaning effect. The results show that low power LD can effectively remove the fingerprint on the surface of absorptive-type attenuator glass plates. On the premise that the attenuator optics glasses are not damaged the cleaning area increases with the increase of radiation time and laser power. The cleaning area doesn't change much with the variation of laser frequency when the other parameters are the same. (2013) Trans Tech Publications Switzerland.

A Local Image Enhancement Method Based on Adjacent Pixel Gray Order-preserving Principle 会议论文 OAI收割
5th International Symposium on Photoelectronic Detection and Imaging (ISPDI) - Infrared Imaging and Applications, Beijing, June 25-27, 2013
作者: Fan XP(范晓鹏); Cai TF(蔡铁峰); Zhu F(朱枫)

收藏 | 浏览/下载：41/0 | 提交时间：2013/12/26

The paper is committed in local image enhancement. At first, the authors propose an adjacent pixel gray order-preserving principle. Adjacent pixel gray order-preserving principle is the basement of local enhancement method which ensures that there is no distortion in processed image. And then, the authors propose an iterative algorithm, which could stretch gray-scale difference of adjacent pixels in premise of not changing gray magnitude relationship between adjacent pixels. At last, the authors propose a totally reference image quality assessment method based on adjacent pixel gray order-preserving principle. According to this quality assessment method, the authors made a set of comparative experiments with local histogram equalization and method. Experimental results show that the proposed enhancement method can get higher score and provide better visual effects, fully demonstrating its effectiveness. According to this quality assessment method, the proposed method shows a good effectiveness, through experimental results and comparison with local histogram equalization method.

Immersed nanospheres super-lithography for the fabrication of sub-70nm nanoholes with period below 700nm (EI CONFERENCE) 会议论文 OAI收割
2012 12th IEEE International Conference on Nanotechnology, NANO 2012, August 20, 2012 - August 23, 2012, Birmingham, United kingdom
作者: Li S.; Du J.; Shi L.

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A maskless nano-lithography method by using polystyrene spheres (PSs) self-assembled on silver slab (NSSL) was proposed in [optics express Vol. 16 No. 19 (2008) 14397]. Following that to break the limitations in resolution and PSs period of NSSL method in this paper we present PSs immersed super-resolution lithography (NSISL) technology by embedding the PSs into appropriate material to improve the efficiency of the surface plasmon excitation. The energy modulating mechanism and the rules of the resolution affected by silver slab were studied by calculating and analysing the energy distribution. The curve of the lithography resolution versus the silver thickness was presented. In order to verify this method contrast analysis was carried out with NSSL. The results show that the lithography resolution is improved efficiently. Taking a specific configuration with PS diameter of 600nm as an example the resolution was improved to 54nm from 190nm with Ag thickness of 25nm. Based on the calculation results we carried out the experiments. Nano holes with dimension of 75nm and period of 600nm were obtained. 2012 IEEE.

Improved TOPS about direction of arrival estimation for wideband signals (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Vibration, Structural Engineering and Measurement, ICVSEM2011, October 21, 2011 - October 23, 2011, Shanghai, China
作者: He B.

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The study about the direction-of-arrival (DOA) estimation for wideband signals is a basic topic of Signal Processing. The method called test of orthogonality of projected subspaces (TOPS) does not require initial values to form focusing matrix compared with the coherent signal subspace method (CSSM) but it has poor performance for coherent wideband signals at low signal-to-noise ratio (SNR). Based on the lack of the conventional TOPS this paper reconstructs a set of new matrices with the narrowband correlated matrices coming from the DFT decomposition of the array output and modifies the method frame of the conventional TOPS. So we get a set of reconstructed matrices with full rank corresponding to each frequency bin and which have no array aperture loss. The improved TOPS can estimate the DOA for coherent wideband sources at low SNR and enhances the performance of the conventional TOPS. Simulation results show that the improved TOPS is effective and the total performance of which is similar to the rotational signal-subspace (RSS) method. (2012) Trans Tech Publications.

Application of trend extrapolation method to spectrum analysis of microtremor signal (EI CONFERENCE) 会议论文 OAI收割
2nd World Congress on Computer Science and Information Engineering, CSIE 2011, June 17, 2011 - June 19, 2011, Changchun, China
Zhou X.; Guo T.; Jiao J.

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The trend extrapolation method is applied to spectrum analysis of microtremor signal in order to increase the spectral estimation accuracy. First establish an appropriate extrapolation model based on the existing data series and then fit correlation functions other than existing data by derivative least squares method finally perform spectrum analysis using extrapolated correlation functions. Numerical simulations and the experimental results show that good results are achieved no matter correlation functions change slow or rapid and the extrapolation error is not more than 2.3%. 2012 Springer-Verlag Berlin Heidelberg.

The angular velocity estimation principal of -- filter based on high sampling rate (EI CONFERENCE) 会议论文 OAI收割
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011, July 15, 2011 - July 17, 2011, Inner Mongolia, China
作者: Zhang Y.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

In order to get angular velocity of stabilization servo mechanism from angular position sensors -- filter and its angular velocity transfer function were predigested. Combing with optimum parameters -- filter based on high sampling rate was established the effect of and sample rate on filter nature frequency were evaluated. According to the requirements of stabilization platform the principle of steady and transient tracking filter differential were proved. With the hypothesis of constant acceleration the frequency characteristics of angular velocity transfer function were analyzed three-dimensional Kalman filter was simplified and the filter parameters were designed. The results show that when the spectrum of input signal was lower than 6rad/s parameters was 0.02 and sampling period were 0.08ms and 0.1ms respectively the filter can realize differential exactly when the spectrum was 9rad/s the precision was no less than 1.1% the phase leading of angular position was no less than 70 the natural frequency should be higher than the cut-off frequency of stabilization platform was two or three times. In the engineering of electro-optical stabilization servo mechanism -- filter has properties of tracking differential and reached the requirement of platform angular velocity estimation. Also it is one of the effective methods to get angular velocity from angular position sensors. 2011 IEEE.

Design of transmission of high-speed CCD driving signals (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Mechatronic Science, Electric Engineering and Computer, MEC 2011, August 19, 2011 - August 22, 2011, Jilin, China
作者: Zhang S.

收藏 | 浏览/下载：71/0 | 提交时间：2013/03/25

In order to overcome the distortion problem of CCD driving signals caused by signal transmission the detail implementation of transmission of high-speed CCD driving signals based on transmission line theory is discussed. The CCD driving signals are critical to the CCD to produce high quality images. In high speed application these drivers will occupy more circuit board areas and can not be put very close to the CCD. So the driving signals must be transmitted. Because the CCD exhibits capacitive load the driving signals distortion problem is much severe. Transmission line theory is used to analyze the problem. The method of source termination is adopted to avoid signal reflections. Meanwhile the characteristic impedance of the circuit board and the resistance of terminal resistor are designed small enough to decrease the rising and falling time of the driving signals. Experimental results show that there is no distortion of the high speed driving signals after transmission. 2011 IEEE.