OALib Journal期刊

ISSN: 2333-9721




2018 ( 1 )

2017 ( 29 )

2016 ( 41 )

2015 ( 539 )


匹配条件: “Chao Yun” ,找到相关结果约22467条。
Aerodynamic Model Analysis and Flight Simulation Research of UAV Based on Simulink  [PDF]
Chao Yun, Xiao-Min Li
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.62007

Mathematical simulation method can be adopted to check flight characteristic of UAV, also can be adopted to simulate hardware experiments of unmanned aerial vehicle (UAV), then related flight experiments can be performed. The simulation method can reduce the flight periods, cost and risk. UAV flight model research play an important role in simulation and modeling in initialize periods of the UAV producing. The study of the paper focuses on the aerodynamic force modeling work of UAV based on Simulink. The designed model not only can afford mathematics simulation experiment but also will do benefits to the research of flight control, navigation guidance of UAV.

Chao-Yun Zhu
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810039413
Abstract: In the title compound, C26H18N4, each ring is almost planar with maximum deviation of 0.012 (5) . In the crystal, molecules are stacked by weak C—H...π interactions, forming a three-dimensional framework.
The $C^1$ density of nonuniform hyperbolicity in $C^{ r}$ conservative diffeomorphisms
Chao Liang,Yun Yang
Mathematics , 2015,
Abstract: Let $\Diff^{ r}_m(M)$ be the set of $C^{ r}$ volume-preserving diffeomorphisms on a compact Riemannian manifold $M$ ($\dim M\geq 2$). In this paper, we prove that the diffeomorphisms without zero Lyapunov exponents on a set of positive volume are $C^1$ dense in $\Diff^{ r}_m(M), r\geq 1$. We also prove a weaker result for symplectic diffeomorphisms $\mathcal{S}ym^{r}_{\omega}(M), r\geq1 $ saying that the symplectic diffeomorphisms with non-zero Lyapunov exponents on a set of positive volume are $C^1$ dense in $\mathcal{S}ym^{r}_{\omega}(M), r\geq1 $.
Fault Ride-Through Study of Wind Turbines  [PDF]
Xinyan Zhang, Xuan Cao, Weiqing Wang, Chao Yun
Journal of Power and Energy Engineering (JPEE) , 2013, DOI: 10.4236/jpee.2013.15004
Abstract: The installation of wind energy has increased rapidly around the world. The grid codes about the wind energy require wind turbine (WT) has the ability of fault (or low voltage) ride-through (FRT). To study the FRT operation of the wind farms, three methods were discussed. First, the rotor short current of doubly-fed induction generator (DFIG) was limited by introducing a rotor side protection circuit. Second, the voltage of DC bus was limited by a DC energy absorb circuit. Third, STATCOM was used to increase the low level voltages of the wind farm. Simulation under MATLAB was studied and the corresponding results were given and discussed. The methods proposed in this paper can limit the rotor short current and the DC voltage of the DFIG WT to some degree, but the voltage support to the power system during the fault largely depend on the installation place of STATCOM.
A Recognition Method of Pedestrians’ Running in the Red Light Based on Image  [PDF]
Min Zhang, Chao Li Wang, Yun Feng Ji
Journal of Software Engineering and Applications (JSEA) , 2014, DOI: 10.4236/jsea.2014.75042
Abstract: It is dangerous for pedestrians to run when the traffic shows a red light, but in some cases the pedestrians are breaking the rules. This system will be a meaningful thing if the jaywalking behaviors of pedestrians in the road crossing through the monitoring cameras could be recognized. Then drivers can be informed of the situations in advance, and they can take some actions to avoid an accident. The characteristic behavior is the non-construction, and furthermore, due to the change of sunlight, temperature, and weather in the outside environment, and the shaking of cameras themselves, the background images will change as time goes by, which will bring special difficulties in recognizing jaywalking behaviors. In this paper, the method of adaptive background model of mixture Gaussian is used to extract the moving objects in the video. On the base of Histograms of Oriented Gradients (HOG), the pedestrians images and car images from MIT Library are used to train our monitoring system by SVM classifier, and identify the pedestrians in the video. Then, the color histogram, position information and the movement of pedestrians are selected to track them. After that we can identify whether the pedestrians are running in the red lights or not, according to the transportation signals and allocated walking areas. The experiments are implemented to show that the proposed method is effective.
A New Type of Damper and Its Field Tests on Ice-coating Transmission Lines  [PDF]
Wan-li Zhong, Wei Wang, Hang-Hang Chen, Wei Luo, Yun-Chao Song
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.51B018
Abstract: The paper developed a type of damper with damping additive, of which the field tests were performed on 220kV transmission line to study its damping effects on vibration of transmission lines. First, based on the common damping measurements, a scheme of filling the damping agent in conventional damper is proposed to suppress the vibration amplitude of the phase/ground line, thus reduce the dynamic stress of the towers and lines and decrease the fatigue damage of the system. Finally, the developed dampers were installed on a 220kV transmission line in GuangdongProvince. The on-line monitoring data show that and the dampers are capable of suppressing the variation of pitch angle and yaw angle of the line, thus verify the effectiveness of the proposed damper.
Community structures of saprophytic soil microfungi in three differently cultivated field soils in the North of China

GAO Yun-Chao,

生态学报 , 2001,
Abstract: The community structure and composition of soil microfungi in different tillage methods have been studied. The fungi recorded were mostly Deuteromycetes. 29 species were isolated from Conventional tillage 0~10 cm soil layer and Chrysosporium merdarium was the most dominant fungi, 17 species in Conventional tillage 10~20 cm soil and Sterile black species A fungus dominant, 10 species in Conventional tillage 20~30 cm soil and Chaetomium bostrychodes dominant; 16 species in Direct drilling 0~10 cm soil and Sterile black species A fungus was the dominant species, 26 species in Direct drilling 10~20 cm soil and sterile black species A fungus was the dominant species, 14 species in Direct drilling 20~30 cm soil and Chaetomium bostrychodes was the dominant species; 23 species in No-tillage 0~10 cm soil and Trichoderma viride and T. koningii were the dominant ones, 14 species in No-tillage 10~20 cm soil and Talaromyces trachyspermus was the dominant one, 9 species in No-tillage 20~30 cm soil and Talaromyces trachyspermus was the dominant one. The diversity was higher in No-tillage fungal community than that in other tillage treatments. Soil microfungal populations existed in No-tillage, Direct drilling, and Conventional tillage soils were characterized by different community compositions.
Equivalence classes of functions on finite sets
Chong-Yun Chao,Caroline I. Deisher
International Journal of Mathematics and Mathematical Sciences , 1982, DOI: 10.1155/s0161171282000696
Abstract: By using P 3lya's theorem of enumeration and de Bruijn's generalization of P 3lya's theorem, we obtain the numbers of various weak equivalence classes of functions in RD relative to permutation groups G and H where RD is the set of all functions from a finite set D to a finite set R, G acts on D and H acts on R. We present an algorithm for obtaining the equivalence classes of functions counted in de Bruijn's theorem, i.e., to determine which functions belong to the same equivalence class. We also use our algorithm to construct the family of non-isomorphic fm-graphs relative to a given group.
Shots Classification for Basketball Video Based on NERFC-Means Clustering
Liu Yun,Chao Huang,Xueying Liu
Journal of Computers , 2011, DOI: 10.4304/jcp.6.7.1444-1451
Abstract: shots classification is the fundamental for sports video annotation. This paper uses non-supervised method to cluster the shots into defined classes (in-play, close-up and free-throw) based on the low-level features of the image (the main color and the histogram). Specifically, we apply the None Euclidean Relational Fuzzy C-means (NERFCM) to cluster the shots after comparing the four Fuzzy C-means and extracting the low-level features of the frames. Experiments prove its efficiency and sensitivity.
A New Data Encryption Algorithm Based on the Location of Mobile Users
Hsien- Chou Liao,Yun -Hsiang Chao
Information Technology Journal , 2008,
Abstract: The wide spread of WLAN and the popularity of mobile devices increases the frequency of data transmission among mobile users. However, most of the data encryption technology is location-independent. An encrypted data can be decrypted anywhere. The encryption technology cannot restrict the location of data decryption. In order to meet the demand of mobile users in the future, a location-dependent approach, called Location-Dependent Data Encryption Algorithm (LDEA), is proposed in this study. A target latitude/longitude coordinate is determined firstly. The coordinate is incorporated with a random key for data encryption. The receiver can only decrypt the ciphertext when the coordinate acquired from GPS receiver is matched with the target coordinate. However, current GPS receiver is inaccuracy and inconsistent. The location of a mobile user is difficult to exactly match with the target coordinate. A Toleration Distance (TD) is also designed in LDEA to increase its practicality. The security analysis shows that the probability to break LDEA is almost impossible since the length of the random key is adjustable. A prototype is also implemented for experimental study. The results show that the ciphertext can only be decrypted under the restriction of TD. It illustrates that LDEA is effective and practical for data transmission in mobile environment.

Copyright © 2008-2017 Open Access Library. All rights reserved.