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The braking index of PSR B0540-69 and the associated pulsar wind nebula emission after spin-down rate transition 期刊论文 OAI收割
Monthly Notices of the Royal Astronomical Society, 2020, 卷号: 494, 页码: 1865-1870
作者: HXMT

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收藏 | 浏览/下载：56/0 | 提交时间：2022/02/08

stars: magnetic field stars: neutron pulsars: general Astrophysics - High Energy Astrophysical Phenomena Abstract: In 2011 December, PSR B054-69 experienced a spin-down rate transition (SRT), after which the spin-down power of the pulsar increased by $\sim 36{{\ \rm per\ cent}}$. About 1000 d after the SRT, the X-ray luminosity of the associated pulsar wind nebula (PWN) was found to brighten by $32\pm 8{{\ \rm per\ cent}}$. After the SRT, the braking index n of PSR B0540-69 changes from n = 2.12 to 0.03 and then keeps this value for about five years before rising to n = 0.9 in the following years. We find that most of the current models have difficulties in explaining the measured braking index. One exceptive model of the braking index evolution is the increasing dipole magnetic field of PSR B0540-69. We suggest that the field increase may result from some instabilities within the pulsar core that enhance the poloidal component at the price of toroidal component of the magnetic field. The increasing dipole magnetic field will result in the X-ray brightening of the PWN. We fit the PWN X-ray light curve by two models: one assumes a constant magnetic field within the PWN during the brightening and the other assumes an enhanced magnetic field proportional to the energy density of the PWN. It appears that the two models fit the data well, though the later model seems to fit the data a bit better. This provides marginal observational evidence that magnetic field in the PWN is generated by the termination shock. Future high-quality and high-cadence data are required to draw a solid conclusion.

PID control of glucose concentration in subjects with type 1 diabetes based on a simplified model: An in silico trial (EI CONFERENCE) 会议论文 OAI收割
10th World Congress on Intelligent Control and Automation, WCICA 2012, July 6, 2012 - July 8, 2012, Beijing, China
作者: Yu L.

收藏 | 浏览/下载：29/0 | 提交时间：2013/03/25

An artificial pancreas system (APS) mimics the function of a real pancreas through monitoring a diabetic's blood glucose and administering the right dose of insulin via an automatic control loop. It is hailed as a promising cure of diabetes though this technology is still years away from commercial use due to a few technological bottlenecks. The simulation model of insulin-glucose metabolism of type 1 diabetes mellitus (T1DM) is an essential part of APS. In order to simplify the parameter identification task so that the model can be implemented electronically with ease this paper presents a simplified model based on Routh approximation model reduction method. The results show that the approximation error between the simplified model and the original model is so small that can be neglected. Based on the simplified model a PID controller is designed to maintain normoglycemia (90mg/dl) in subjects with T1DM. The in silico simulation results show that the glucose concentration is controlled well the risk of hyperglycemia and hypoglycemia is reduced a lot. This suggests that the simplified model describes the insulin-glucose metabolism process accurately and the PID control algorithm is well-suitable to guide the further development of an APS. 2012 IEEE.

The effect of substrate on powder concentration distribution in coaxial laser cladding 会议论文 OAI收割
23rd International Congress of Theoretical and Applied Mechanics, 中国北京/Beijing, China, 2012-08-19
作者: Liu H(刘昊); Jin SW(靳绍魏); He XL(何秀丽); Yu G(虞钢)

收藏 | 浏览/下载：26/0 | 提交时间：2014/03/19

substrate cladding laser distribution powder coaxial concentration effect thermal nozzle without between large formed enough steady though results search model

Optimum design of the carbon fiber thin-walled baffle for the space-based camera (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Yan Y.; Gu S.; An Y.; Jin G.

收藏 | 浏览/下载：14/0 | 提交时间：2013/03/25

The thin-walled baffle design of the space-based camera is an important job in the lightweight space camera research task for its stringent quality requirement and harsh mechanical environment especially for the thin-walled baffle of the carbon fiber design. In the paper an especially thin-walled baffle of the carbon fiber design process was described and it is sound significant during the other thin-walled baffle design of the space camera. The designer obtained the design margin of the thin-walled baffle that structural stiffness and strength can tolerated belong to its development requirements through the appropriate use of the finite element analysis of the walled parameters influence sensitivity to its structural stiffness and strength. And the designer can determine the better optimization criterion of thin-walled baffle during the geometric parameter optimization process in such guiding principle. It sounds significant during the optimum design of the thin-walled baffle of the space camera. For structural stiffness and strength of the carbon fibers structure which can been designed the effect of the optimization will be more remarkable though the optional design of the parameters chose. Combination of manufacture process and design requirements the paper completed the thin-walled baffle structure scheme selection and optimized the specific carbon fiber fabrication technology though the FEM optimization and the processing cost and process cycle are retrenchment/saved effectively in the method. Meanwhile the weight of the thin-walled baffle reduced significantly in meet the design requirements under the premise of the structure. The engineering prediction had been adopted and the related result shows that the thin-walled baffle satisfied the space-based camera engineering practical needs very well its quality reduced about 20% the final assessment index of the thin-walled baffle were superior to the overall design requirements significantly. The design method is reasonable and efficient to the other thin-walled baffle that mass and work environment requirement is requirement harsh. 2011 SPIE.

Angular rate of test table based on high-speed non-contact measurement (EI CONFERENCE) 会议论文 OAI收割
9th International Conference on Electronic Measurement and Instruments, ICEMI 2009, August 16, 2009 - August 19, 2009, Beijing, China
作者: Yang L.; Zhao Y.; Zhao Y.; Zhao Y.; Yang L.

收藏 | 浏览/下载：139/0 | 提交时间：2013/03/25

This article will introduces a high-speed non-contact method that can measures the angular rate of a test table though an objective perspective. This method adopts a collimator tube that can be measured as a target fixed to the test table and the target corresponds to the angular position of the test table. In the process of the table rotating the camera will to keep track of the objective at a high speed. Due to the high sampling frequency of the high-speed camera instantaneous angular rate of test table can be measured. With pixel subdivision technology its measuring accuracy can be up to 0.02 pixels. We use this methods measured a low-speed test table's angular rate and analyzed the data. The error analysis shows when the rate of the test table is 0.20/s the accuracy of the method can achieve 0.0220%. 2009 IEEE.

A comparative study of discrete differential evolution on binary constraint satisfaction problems (EI CONFERENCE) 会议论文 OAI收割
2008 IEEE Congress on Evolutionary Computation, CEC 2008, June 1, 2008 - June 6, 2008, Hong Kong, China
Yang Q.

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There are some variants and applications of the discretization of differential evolution. Performances of discrete differential evolution algorithms on random binary constraint satisfaction problem are studied in this paper and a novel discrete differential evolution algorithm based on exchanging elements is proposed. We compare the proposed discrete differential evolution evolutionary algorithms and discrete particle swarm optimization on random binary constraint satisfaction problems. Experimental results indicate though the proposed algorithm is simpler it is competitive with other evolutionary algorithms solving constraint satisfaction problems. 2008 IEEE.

Composite-structure frequency selective surface with tripole elements (EI CONFERENCE) 会议论文 OAI收割
8th International Symposium on Antennas, Propagation and EM Theory, ISAPE 2008, November 2, 2008 - November 5, 2008, Kunming, China
作者: Gao J.

收藏 | 浏览/下载：72/0 | 提交时间：2013/03/25

Two composite symmetry structure is proposed in this paper. Based on the integral equation method the frequency response with large incident angle effect is analyzed. As a result of the numerical analysis it is shown that the composite symmetry structure with single FSS screen is efficient to stabilize the drift of FSS resonant frequency with the steering of incident angle though transmission loss increased. Especially the structure that the FSS is embedded centrally in the dielectrics has better frequency characteristic with flat top and sharp skirts. The studies have indicated the versatility of the proposed structure. 2008 IEEE.

Contour extracting with combination particle filtering and em algorithm (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging, ISPDI 2007: Related Technologies and Applications, September 9, 2007 - September 12, 2007, Beijing, China
Meng B.; Zhu M.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

The problem of extracting continuous structures from images is a difficult issue in early pattern recognition and image processings[1]. Tracking with contours in a filtering framework requires a dynamical model for prediction. Recently Particle filter is widely used because its multiple hypotheses and versatility within framework. However the good choice of the propagation function is still its main problem. In this paper an improved particle filter EM-PF algorithm is proposed which using the EM (Expectation-Maximization) algorithm to learn the dynamical models. The EM algorithm can explicitly learn the parameters of the dynamical models from training sequences. The advantage of using the EM algorithm in particle filter is that it is capable of improve tracking contour by having accurate model parameters. Though the experiment results we show how our EM-PF can be applied to produces more robust and accurate extracting.

The study on the temperature influence of the grain near infrared spectrum analysis (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
作者: Zhang J.; Chen X.; Chen X.; Chen X.; Zhang J.

收藏 | 浏览/下载：26/0 | 提交时间：2013/03/25

Near-infrared spectroscopy was used to examine unmodified wheat powder at temperatures of 14-65C. A self-regulating diffuse reflected assembly was used to permit collection of spectra of powder samples. Changes to the shape and peak location of the 1400-1500nm and 1900-1950nm water absorption bands 2000-2050 2070-2110 and 2250-2300nm bands were measured as temperature varied. Results indicated that temperature changes resulted in slight changes to the water absorption bands in 1400-1500nm and 1900-1950nm regions. From 14-65C the 1400-1500nm and 2050-2150nm band shifted approximately 10nm and 16nm toward shorter wavelengths and 2000-2050nm band shifted approximately 14nm toward longer wavelengths. In addition few numbers of samples cannot constitute good temperature insensitive calibration model even though the spectra were obtained at wide temperature condition.

Aerial image blurring caused by image motion and its restoration using wavelet transform (EI CONFERENCE) 会议论文 OAI收割
Electronic Imaging and Multimedia Technology IV, November 8, 2004 - November 11, 2004, Beijing, China
作者: Liu G.

收藏 | 浏览/下载：33/0 | 提交时间：2013/03/25

A wavelet-based approach of aerial blurred image restoration is proposed in this article. Image motion is inevitable in photographing for aerospace camera. Though some Image Motion Compensation(IMC) schemes are applied in aerial imaging system the ultimate image will be blurred in certain extent for the existence of IMC residual error while the forward image motion is the key element among all image motions which lead to image blurring. First the course of blurring caused by forward image motion is expressed using wavelet transform and a multiresolution sparse matrix representation of the degeneration model is obtained according to the wavelet transform. Subsequently a regularizing restoration algorithm is deduced from it and which can smoothly restraint the processed result efficiently. In the end the proposed approach is tested in MATLAB. The blurred image is restored using above-mentioned wavelet algorithm conventional contrary filter and Wiener filter algorithm separately. The conclusion that the wavelet-based restoration algorithm is superior to other two approaches is obtained by comparing the restored image's value of mean gradient. The calculating quantity of the wavelet-based blurred image restoration approach isn't large and it has good practicability in the field of image interpretation and aerial survey or drawing.