Equivalent stiffness and dynamic response of new mechanical elastic wheel

To investigate the stiffness characteristics of the new mechanical elastic wheel (MEW), the elastic foundation closed circle curved beam model of MEW was established by curved beam theory. With the Laplace transformation and boundary conditions of the governing differential equations, the analytical relations among the radial deformation, bending stiffness of elastic wheel, the elastic foundation stiffness of hinges, elastic wheel laminated structure parameters and excitation frequency were analyzed. The correctness of the curved beam model was validated by the finite element method. Curved beam model validation and the application of the nonlinear finite element model show that the influence of elastic wheel laminated structure and deformation on dynamic response is equal to the equivalent stiffness. The results indicate that the equivalent stiffness and dynamic response of MEW become increased nonlinearly with component content of elastic bead ring, moreover, the equivalent stiffness and dynamic response of MEW increase nonlinearly with the deformation amount of MEW, and the dynamic response significantly decreases with the increase of excitation frequency, under this circumstance that the laminated structure of elastic wheel has been unchanged

Distinctive action sketch for human action recognition

Recent developments in the field of computer vision have led to a renewed interest in sketch correlated research. There have emerged considerable solid evidence which revealed the significance of sketch. However, there have been few profound discussions on sketch based action analysis so far. In this paper, we propose an approach to discover the most distinctive sketches for action recognition. The action sketches should satisfy two characteristics: sketchability and objectiveness. Primitive sketches are prepared according to the structured forests based fast edge detection. Meanwhile, we take advantage of Faster R-CNN to detect the persons in parallel. On completion of the two stages, the process of distinctive action sketch mining is carried out. After that, we present four kinds of sketch pooling methods to get a uniform representation for action videos. The experimental results show that the proposed method achieves impressive performance against several compared methods on two public datasets.The work was supported in part by the National Science Foundation of China (61472103, 61772158, 61702136, and 61701273) and Australian Research Council (ARC) grant (DP150104645)

Research on vibration characteristics and its key influencing factors of new mechanical elastic wheel

This paper presents the vibration characteristics and its key influencing factors of a new mechanical elastic wheel (MEW). The MEW was modeled as a ring on elastic foundations (REF) with distributed spring stiffness in the radial and tangential directions. The general forced solutions of inextensible vibration were derived by the use of a modal expansion technique and Arnoldi method, and the accuracy of the solutions had been validated by FEM simulation and modal test under free suspension and various loading situations. The natural frequencies and mode shapes of the rotating MEW could be obtained under free suspension and various loading situations. Moreover, the effects of various rotational speed, loading and different number of hinges on natural frequencies were investigated. Finally, the effect of different number of hinges on the damping ratio of the MEW radial modes was also analyzed. The analysis results reflect the objective law of the actual vibration characteristics of the MEW, and provide a reference for the MEW structure optimization and the vibration characteristics of the whole vehicle

Equivalent stiffness and dynamic response of new mechanical elastic wheel

To investigate the stiffness characteristics of the new mechanical elastic wheel (MEW), the elastic foundation closed circle curved beam model of MEW was established by curved beam theory. With the Laplace transformation and boundary conditions of the governing differential equations, the analytical relations among the radial deformation, bending stiffness of elastic wheel, the elastic foundation stiffness of hinges, elastic wheel laminated structure parameters and excitation frequency were analyzed. The correctness of the curved beam model was validated by the finite element method. Curved beam model validation and the application of the nonlinear finite element model show that the influence of elastic wheel laminated structure and deformation on dynamic response is equal to the equivalent stiffness. The results indicate that the equivalent stiffness and dynamic response of MEW become increased nonlinearly with component content of elastic bead ring, moreover, the equivalent stiffness and dynamic response of MEW increase nonlinearly with the deformation amount of MEW, and the dynamic response significantly decreases with the increase of excitation frequency, under this circumstance that the laminated structure of elastic wheel has been unchanged

Comparison of Bacterial Communities in Two Partial Nitrification Systems for High-ammonia Wastewater and Sewage Treatment

ABSTRACT Partial nitritation is an important part of the biological nitrogen removal processes; it saves half of the aeration energy, since only half of NH 4 + -N need to be oxidized to nitrite. The performance of the process was determined by the microbial community structure. In this study, we measured the microbial diversity in terms of the quantity of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) that were present. The results revealed that the amount of aerobic bacteria did not change significantly in high-ammonia wastewater, but decreased significantly with running time in sewage. The abundance of AOB and NOB in high-ammonia wastewater ranged from 1.23 × 10 7 to 8.95 × 10

Heparan sulfate is the attachment factor associated with channel catfish virus infection on host cells

Channel catfish virus (CCV; family Alloherpesviridae) infects channel catfish, causing great harm to aquaculture fisheries and economic development. Attachment is the first step in viral infection and relies on the interaction of virions with components of the extracellular matrix (ECM). The present study aimed to explored the role of the main three ECM components in CCV attachment. Western blotting and quantitative real-time PCR analysis showed that neither collagen nor hyaluronic acid treatments had significant effects on CCV attachment. When exogenous heparin was used as a competitive inhibitor, the adhesion of heparin sodium salt to CCV was dose-dependent. When the concentration of heparin sodium salt was 10 mg/mL, the inhibitory effect on CCV infection of channel catfish ovary (CCO/BB) cells was more than 90%. Heparinase I could significantly prevent CCV attachment by digesting heparan sulfate on the cell surface, and both heparin sodium salt and heparinase I could dose-dependently reduce CCV titers, suggesting that heparin plays an important role in CCV attachment. In addition, the binding experiments between heparin-agarose beads and virions showed that CCV virions could specifically bind to heparin in a dose-dependent manner. The above results suggested that heparan sulfate might be an attachment factor involved in CCV infection of CCO/BB cells. These results increase our understand of the attachment mechanism of CCV and lay the foundation for further research on antiviral drugs

Estimation of Atmospheric Turbidity from a Sky Image and Its Applications

Atmospheric turbidity is defined as the ratio of optical thickness of the haze atmosphere as opposed to molecules, it is widely used in the computer graphics and vision community for modeling the outdoor illumination. This thesis proposes a novel method for estimating the atmospheric turbidity and provides three applications. Specifically, the atmospheric turbidity is estimated by matching the brightness distribution between a sky model and an actual image. By using the estimated turbidity, we recover the spectral sensitivity and white-balance parameters of digital cameras from sky images, render the virtual object with turbidity-based aerial perspective calculation, estimate the reflectance of outdoor diffuse object from a single perspective image. Camera spectral sensitivity plays an important role for many physics-based computer vision methods, such as demosaicing, color correction and illumination estimation. However, less attention has been paid to estimating the spectral sensitivity. This is unfortunate, because this parameter significantly affect the image colors. We have proposed a novel method for estimating the spectral sensitivity from images. A basic idea is to use a sky image from which the spectra of the sky can be inferred. Given the input image, the atmospheric turbidity is estimated by fitting the brightness distribution to a sky model. Assuming the sun direction with respect to the camera view direction can be estimated, the sky spectra is calculated from the estimated turbidity. Having obtained the pairs of image RGB values and corresponding spectra, the spectral sensitivity is calculated by using basis-functions. The basis functions are extracted from the database which consists of collected spectral sensitivities of different digital cameras. The utilization of the basis functions makes the estimation accurate and robust. Virtual object rendering has been widely used in the academy, the architecture, the entertainment and the heritage preservation. Aerial perspective plays an important rule for making the rendered image appear realistic, especially when the object is distant from the camera. The aerial perspective is caused by the scattering of particles in the atmosphere, it models the slight color change of distant object. The virtual object rendering with the aerial perspective effect is described. The spectral radiance of the sun and skylight is first calculated from the estimated turbidity, and the aerial perspective effect is calculated as the summation of in-scattered and out-scattered light along the camera view direction. Experimental results shows the accuracy of this technique. Three-dimension models have been widely used in many fields. The reflectance is necessary for making a realistic 3D model. However, how to estimate the accurate reflectance still remains a challenge, especially for outdoor objects, because it is difficult to precisely model the outdoor illumination. Many trials have been made to capture the outdoor illumination, but these methods need expensive equipments and massive calibrations. We propose a novel method for estimating the reflectance of outdoor diffuse object from a single perspective image. The atmospheric turbidity is first estimated from the input image, and then the whole illumination condition is recovered from the estimated turbidity. The reflectance is calculated from the surface radiance and irradiance value. The proposed method also solves the problem of inter-reflection, which exists between concave surfaces. We assume the object surface consists of hundreds of small facets, and the inter-reflection is calculated as the incoming light energy from all other facets. Experimental results show the accuracy achieved by the proposed method. The main contributions of this thesis are that a novel atmospheric turbidity estimation method and its three applications. It can be summarized by the four following points: First, the atmospheric turbidity is estimated by matching the brightness distributions between a sky model and an actual image. Second, the estimated atmospheric turbidity is used for recovering the camera spectral sensitivity and white balance parameters. Third, the estimated atmospheric turbidity is used to calculate the aerial perspective effect which makes the rendered image appear realistic. Fourth, the estimated atmospheric turbidity is used to model the outdoor illumination environment for estimating the reflectance of outdoor diffuse object.報告番号: ; 学位授与年月日: 2012-09-27 ; 学位の種別: 課程博士 ; 学位の種類: 博士(情報理工学) ; 学位記番号: ; 研究科・専攻: 情報理工学系研究科電子情報学専

Estimating Key Components for Physics-Based Vision: Reflectance Estimation with the Presence of Inter-reflection and Camera Sensitivity Recovery

報告番号: ; 学位授与年月日: 2009-09 ; 学位の種別: 修士 ; 学位の種類: 修士(情報理工学) ; 学位記番号: ; 研究科・専攻: 情報理工学系研究科電子情報学専