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Study of vortex in flow fields induced by surface dielectric barrier discharge actuator at low pressure based on Q criterion

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Plasma Science and Technology 2018年第1期20卷 41-46页

作者：张政车学科聂万胜李金龙郑体凯李亮陈庆亚郑直 equipment academy

Flow fields induced by a surface dielectric barrier discharge actuator at low pressure of 7 kPa are measured by particle image velocimetry. The distribution of local vortices in the flow field is revealed by the Q criterion. The reason for the generation of vortices is analyzed and the influence of pulse frequency and duty cycle on vortices is studied. The results show that the Q criterion can reveal the small-scale vortices, which cannot be indicated by the streamline. The direction transition zone where the induced jet moves from the vertical to the tangential and the shear layer between the jet and stationary air are prone to the generation of strong vortices. The influence of pulse frequency on vortices is not obvious, but the variation of duty cycle can significantly affect the strength and distribution of vortices.

关键词： low pressure SDBD induced field Q criterion vortex

Affine & Scale-Invariant Heterogeneous Pyramid Features for Automatic Matching of High Resolution Pushbroom Imagery from Chang'e 2 Satellite

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Journal of Earth Science 2016年第4期27卷 716-726页

作者： Sheng Yang Shibing Zhu Zhenju Li Xuejun Li Tao Liu Jue Wang Jianwei Xie Department of Information equipment the Equipment Academy

The automatic feature extracting and matching for large amount of linear pushbroom imagery with higher and higher resolution is urgent and challenging in three dimensional reconstructions, remote sensing and mapping. Affine ＆ scale-invariant heterogeneous pyramid feature is proposed in this paper, along with the new scale-invariant analysis method, the detecting of the key points, the affine ＆ scale-invariant descriptor, the steering method of the matching, and the quasi-dense matching algorithm based on the extensive epipolar geometry. The automatic matching is devised for the linear pushbroom imagery. The whole process is executed on lunar images of the highest resolution of ~7 m/pixel（or ~1 m/pixel in the lower orbits） from the Chinese Chang＇e 2 satellite, it runs robustly at present, and resulting in large amounts of well-distributed-correspondences with accuracy of 0.3 pixels and excellent reliability, which gives great support for the further exploration both on the Moon and the Earth.

关键词： image matching linear pushbroom imagery epipolar geometry quasi-dense matching.

Interactive Details on Demand Visual Analysis on Large Attributed Networks

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Chinese Journal of Electronics 2018年第5期27卷 900-909页

作者： DU Xiaolei WEI Yingmei WU Lingda College of Information System and Management National University of Defense Technology The Key Laboratory of the academy of equipment Equipment Academy

Increasing scale leaves a challenging problem for visualizing large attributed networks. This paper proposes a details on demand approach for exploratory visual analysis on large attributed networks. Ma jor structures are located and emphasized at each level, providing clues for user observation. The detailed subnet structure emerges gradually through the exploration *** method dynamically aggregates network with consideration of both structural and attribute properties. It allows a flexible control of the hierarchy structure. A userspecified interaction strategy is introduced to enable users to customize the analysis flow according to different analytic tasks. Case studies demonstrate that the proposed method is effective in extracting global knowledge, locating ma jor structures, and discovering hidden information in networks.

关键词： Large attributed networks Visual analytics Content-based approach Details on demand

Bearing Fault Diagnosis Based on the Markov Transition Field and SE-IShufflenetV2 Model

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Structural Durability & Health Monitoring 2025年第1期19卷 125-144页

作者： Chaozhi Cai Tiexin Xu Jianhua Ren Yingfang Xue School of Mechanical and equipment Engineering Hebei University of EngineeringHandan056038China

A bearing fault diagnosis method based on the Markov transitionﬁeld(MTF)and SEnet(SE)-IShufﬂenetV2 model is proposed in this paper due to the problems of complex working conditions,low fault diagnosis accuracy,and poor generalization of rolling ***,MTF is used to encode one-dimensional time series vibration sig-nals and convert them into time-dependent and unique two-dimensional feature ***,the generated two-dimensional dataset is fed into the SE-IShufﬂenetV2 model for training to achieve fault feature extraction and classiﬁ*** paper selects the bearing fault datasets from Case Western Reserve University and Paderborn University to experimentally verify the effectiveness and superiority of the proposed *** generalization performance of the proposed method is tested under the variable load condition and different signal-to-noise ratios(SNRs).The experimental results show that the average accuracy of the proposed method under different working conditions is 99.2%without adding *** accuracy under different working conditions from 0 to 1 HP is 100%.When the SNR is 0 dB,the average accuracy of the proposed method can still reach 98.7%under varying working ***,the bearing fault diagnosis method proposed in this paper is characterized by high accuracy,strong anti-noise ability,and ***,the proposed method can also overcome the inﬂuence of variable working conditions on diagnosis accuracy,providing method support for the accurate diagnosis of bearing faults under strong noise and variable working conditions.

关键词： Bearings Markov transitionﬁeld SE-IShufﬂenetV2

Study of spiral cruising surveillance orbit for GEO debris

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Journal of Beijing Institute of Technology 2016年第S2期25卷 68-72页

作者：周海俊张雅声徐艳丽李智 Company of Postgraduate Management Equipment Academy Department of Space equipment Equipment Academy Department of Space Command Equipment Academy

A new type of relative orbit configuration for space target surveillance is proposed,performing autonomous rendezvous,proximity and surveillance operations with multiple non-cooperative targets at geosynchronous orbit in spiral precession *** deviation orbit element is used to describe the relative motion characteristics of the spiral cruising surveillance orbit,and the necessary condition to perform spiral precession is *** features of the spiral ring in the in-plane of the target orbit are detailedly *** position of the crossing point,the relationship between the fly-around period of the spiral ring and the relative configuration parameters is *** avoid the collision with the debris,two schemes of the relative orbit configuration are *** is carried out to verify the performance of the spiral cruising surveillance orbit by satellite tool kits(STK).

关键词： space target surveillance orbit design small deviation orbit element spiral cruising orbit spiral ring

Failure Mode Effects and Criticality Analysis Method of Armored equipment Based on Testability Growth

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Journal of Donghua University(English Edition) 2018年第3期35卷 252-255页

作者：曹艳华郭金茂吕会强 Department of equipment Support and Remanufacture Academy of Armored Forces for Army

In view of the low level testability of armored equipment,the important significance of armored equipment testability growth is discussed in this *** failure mode effects and criticality analysis( FMECA) method to realize testability growth is *** on the testability growth demands of new armored equipment,the deficiencies of traditional FMECA are *** an enhanced FMECA( EFMECA) method is *** method increases the analysis contents,combines the information before the failure occurrence and impending failure modes together *** the failure symptoms is analyzed,the failure modes and effects is determined,and the state development trend is ***,the application of EFMECA method is illustrated by the example of the failure mode of typical armored equipment engine.

关键词： testability growth armored equipment the failure mode effects and criticality analysis(FMECA) design of testability

An Approximate Analytical Propagation Formula for Gaussian Beams through a Cat-Eye Optical Lens under Large Incidence Angle Condition

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Chinese Physics Letters 2011年第7期28卷 114-117页

作者： ZHAO Yan-Zhong SUN Hua-Yan ZHENG Yong-Hui academy of equipment Command and Technology Beijing 101416

Based on the generalized diffraction integral formula and the idea that the angle misalignment of the cat-eye optical lens can be transformed into the displacement misalignment,an approximate analytical propagation formula for Gaussian beams through a cat-eye optical lens under large incidence angle condition is *** results show that the diffraction effect of the apertures of the cat-eye optical lens becomes stronger along with the increase in incidence *** results are also compared with those from using an angular spectrum diffraction integral and experiment to illustrate the applicability and validity of our theoretical *** is shown that the approximate extent is good enough for the application of a cat-eye optical lens with a radius of 20 mm and a propagation distance of 100 m,and the approximate extent becomes better along with the increase in the radius of the cat-eye optical lens and the propagation distance.

关键词： approximate radius Gaussian

Three-Dimensional Analytical Formula for Oblique and Off-Axis Gaussian Beams Propagating through a Cat-Eye Optical Lens

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Chinese Physics Letters 2010年第3期27卷 128-131页

作者：赵延仲孙华燕喻夏琼樊萌山 academy of equipment Command and Technology Beijing 101416

Based on the Collins formula in a cylindrical coordinate system and the method of introducing a hard aperture function into a finite sum of complex Gaussian functions, an approximate three-dimensional analytical formula for oblique and off-axis Gaussian beams propagating through a cat-eye optical lens is derived. Numerical results show that a reasonable choice of the obliquity factor would result in a better focus beam with a higher central intensity at the return place than that without obliquity, whereas the previous conclusion based on geometry optics is that the highest central intensity could be obtained when there is no obliquity.

关键词： Mathematical physics Optics quantum optics and lasers

Cleaning space debris with a space-based laser system

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Chinese Journal of Aeronautics 2014年第4期27卷 805-811页

作者： Shen Shuangyan Jin Xing Chang Hao State Key Laboratory of Laser Propulsion Equipment Academy

High-energy pulsed laser radiation may be the most feasible means to mitigate the threat of collision of a space station or other valuable space assets with orbital debris in the size range of 1–10 cm. Under laser irradiation, part of the debris material is ablated and provides an impulse to the debris particle. Proper direction of the impulse vector either deflects the object trajectory or forces the debris on a trajectory through the upper atmosphere, where it burns up. Most research concentrates on ground-based laser systems but pays little attention to space-based laser *** are drawbacks of a ground-based laser system in cleaning space debris. Therefore the placement of a laser system in space is proposed and investigated. Under assumed conditions,the elimination process of space debris is analyzed. Several factors such as laser repetition frequency, relative movement between the laser and debris, and inclination of debris particles which may exercise influence to the elimination effects are discussed. A project of a space-based laser system is proposed according to the numerical results of a computer study. The proposed laser system can eliminate debris of 1–10 cm and succeed in protecting a space station.

关键词： Laser ablation Laser system Orbital transfer Space-based Space debris