A Novel Micro-Contact Stiffness Model for the Grinding Surfaces of Steel Materials Based on Cosine Curve-Shaped Asperities

Contact stiffness is an important parameter for describing the contact behavior of rough surfaces. In this study, to more accurately describe the contact stiffness between grinding surfaces of steel materials, a novel microcontact stiffness model is proposed. In this model, the novel cosine curve-shaped asperity and the conventional Gauss distribution are used to develop a simulated rough surface. Based on this simulated rough surface, the analytical expression of the microcontact stiffness model is obtained using contact mechanics theory and statistical theory. Finally, an experimental study of the contact stiffness of rough surfaces was conducted on different steel materials of various levels of roughness. The comparison results reveal that the prediction results of the present model show the same trend as that of the experimental results; the contact stiffness increases with increasing contact pressure. Under the same contact pressure, the present model is closer to the experimental results than the already existing elastic–plastic contact (CEB) and finite-element microcontact stiffness (KE) models, whose hypothesis of a single asperity is hemispherical. In addition, under the same contact pressure, the contact stiffness of the same steel material decreases with increasing roughness, whereas the contact stiffness values of different steel materials under the same roughness show only small differences. The correctness and accuracy of the present model can be demonstrated by analyzing the measured asperity geometry of steel materials and experimental results.

Enhancement Algorithm of Color Fog Image Based on the Adaptive Scale and S-Cosine Curve

To deal with the image contrast and color fidelity details problem in the traditional Center around the Retinex image enhancement algorithms, Enhancement algorithm of color fog image based on the adaptive scale and s-cosine curve is proposed. Firstly, the image is transformed into the RGB color space. Then the each channel pixel values can be stretched the grayscale range by S-cosine curve and introduces the local correction function. It can calculate the scale of the Gaussian kernel, and then proceeds to do the Gamma correction for the estimates of the reflection component, obtains the multi-scale image by the weighted average. Afterwards, the obtained image is used to global nonlinear correction, image sharpening and smoothing, and being superimposed reflection components, achieving the image enhancement. At last, it can carry on the intensity adjustment and grayscale adjustment for the obtained image. Through the subjective observation and objective evaluation, this algorithm is better than the traditional center around Retinex algorithm and MSRCR algorithm in processing effect.

Pre-Camber Analysis for Hanging Cradle Construction of Qinhe Bridge

In order to ensure the safety of long-span continuous prestressed concrete girder bridge constructed by hanging cradle method, a pre-camber is always made to reduce shrinkage and creep in the process of post-operation, the late loss of pre-stressed, deformation produced by live load and so on. Combining with Qinhe Bridge, how to install the pre-camber is studied in this paper. The maximum pre-cambers and their locations of every span of Qinhe Bridge are determined by the method of standard JTG D62-2004 with the finite element analysis software MIDAS/CIVIL. The results show that the final pre-camber curves calculated by the method of standard JTG D62-2004 and quadratic parabolic method have cusps, which cannot meet the standard requirements for the smooth of the bridge. But the slop of the final pre-camber curve calculated by cosine curve at the maximum pre-cambers and the pier top is zero, and the slop of curve from pier top to the mid-span is small, which satisfy the standard requirements for the smooth of bridge. Therefore, the final pre-camber curve should be calculated by cosine curve.

The Simulation of Vibration Mechanism and Dynamics Analysis of Eccentric Shaft of Billet Caster

The model of vibration mechanism is built with Pro/E software. Simulate the vibration mechanism and obtain the cosine curve of the vibration table in the vertical direction by Pro/E. Afterwards, perform transient dynamics analysis of eccentric shaft in the vibration mechanism, and get the maximum average stress and the dangerous section. The simulation is correct and the dynamics analysis is accurate, which lays the foundation for the analysis, design and manufacture.

Study on Mathematical Model of Homogenization of Dendritic Segregation

The cosine solution of the Fick-2 Law, which was considered as the mathematical model of homogenization of dendritic segregation, has always been used to analyze high temperature diffusion. Cosine solution can not exactly describe the actual distribution of alloying elements in dendrite, as the slope of cosine curve is quite gentle. Based on segregation ratio SR, a new mathematical model was established by using Gauss solution of the Fick-2 Law. The new model could describe the evolution of homogenization of alloying elements during the process of high temperature, which was proved by some specific examples.

A model to search for birth probabilities of mammal populations using fertility data

A model was constructed to predict monthly birth probabilities using mammalian fertility data. We used a sample of 147 female capybaras (Hydrochoerus hydrochaeris) hunted on a farm on Marajó Island, Brazil. In the model each month was treated as a multinomial with six cells representing the six possible reproductive states (five months gestation). A hypothesis test was carried out to see whether a cosine curve would fit the birth probabilities. The results offer no support for a seasonal component (F2,9 = 1.84, P = 0.21), whereas results from a direct census do (F3,23 = 87.29, P < 0.01). Some hunting techniques were biased towards killing pregnant females (χ(2)1= 7.2, P< 0.01), thereby spreading reproduction throughout the year (F2,9 = 1.84, P = 0.21). The model remained a powerful predictive tool to be used with mammalian fertility data as long as the data are not biased towards pregnant females.

How to Model a Bonded Joint

The problem is considered of a semi-infinite plane region bonded to a rigid region, with the boundary of contact being in the shape of a cosine curve. It is shown that, when a rigid displacement is applied to the boundary of the elastic region, there is a particular value of the amplitude of the contact curve that minimizes the sum of the strain energy and adhesion energy.