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A new stochastic stock price model of stock markets based on the contact process of the statistical physics systems is presented in this paper, where the contact model is a continuous time Markov process, one interpretation of this model is as a model for the spread of an infection. Through this model, the statistical properties of Shanghai Stock Exchange (SSE) and Shenzhen Stock Exchange (SZSE) are studied. In the present paper, the data of SSE Composite Index and the data of SZSE Component Index are analyzed, and the corresponding simulation is made by the computer computation. Further, we investigate the statistical properties, fat-tail phenomena, the power-law distributions, and the long memory of returns for these indices. The techniques of skewness–kurtosis test, Kolmogorov–Smirnov test, and R/S analysis are applied to study the fluctuation characters of the stock price returns.

This paper presents the method of grading of cervical cancer images according to cell formation in the tissue. The variation of intensity and texture complexity of cancer cell images are calculated by fractal dimension methods. Box Counting Method (D_B) and HarFA Programme software are used to find out the dimension of the cells. Contact model and Epidemic Model are the two different models used here. The contact model shows the contact of the cells and the formation of the cancer in the part of the organ. The Epidemic model shows the growth of cancer. Lacunarity is formed between the cells. If the Lacunarity increases the dimension also increases. On seeing the growth of the cancer cell the pathologist can determine the grade of the cancer which in turn will help him to diagnose the cervical cancer and recommend appropriate treatment.

In this work, we establish a fractal contact model and analyze the effect of the parameters on stress. The study provided a method to make a link between contact characteristics and surface condition. The surface texture model was built based on the process mechanism of point grinding. The experiment for the effect of the surface texture on contour height was carried out on TR300 roughness shape-measuring instrument and the structural function method of fractal theory was used to obtain the fractal dimensions and scale coefficients of surfaces with different surface textures. The fractal contact model was established based on the fractal characteristics of the surface point ground and the simulation was carried out using Matlab. Furthermore, the validation of compression experiment was carried out by WAW-600C universal testing machine, the high-definition pictures before and after the experiment were obtained by KEYENCE VH-Z500R ultra-depth-of-field 3D microscope and the surface topographies before and after the experiment were obtained by NANOVEA PS50 three-dimensional noncontact surface profile meter. The obtained findings can help to choose appropriate surface with the best contact characteristics under certain condition.

In this paper, several finite element models of an equine stifle joint with varying meniscal properties and attachments are compared to understand the effects of meniscal attachment complexity and material property changes on bone stresses. We found that the complexity in the meniscal attachment is critical when evaluating tensile stresses in the bone. We also demonstrate that simplified material properties may be justified when the relationship between each material property and the desired output variables is well understood. The choice of the most efficient, and yet appropriate, meniscal modeling method depends on the goals of the model.

We introduce a continuous version of the contact model which is well known and widely studied in the lattice case. Under certain general assumptions on the infection spreading characteristics, we construct the contact process as a Markov process in the configuration space of the system.

We study the continuous version of the contact model. Using an analytic approach, we construct the non-equilibrium contact process as a Markov process on configuration space. The construction is based on the analysis of correlation functions evolution. The problem concerning invariant measures as well as asymptotics of correlation functions are also studied.

The actual dead load of an arch dam should be applied gradually through staged construction and sequenced grouting. However, the cantilever- and integral-type dead loads commonly used in the analysis of arch dams represent simplified versions of the actual loading. In this paper, these two types of dead loads, i.e. cantilever and integral types, are presented based on the Lagrange multiplier method considering the nonlinear behaviors of contraction joints. Based on the finite element method and an appropriate contact model together with artificial viscoelastic boundary conditions, a dynamic analysis model of a dam–foundation–reservoir system is established in consideration of the interactions between the arch dam and foundation, the opening and closing of contraction joints, and the radiation damping effect of the far-field boundary. Taking a 300 m high arch dam in the strong earthquake area of West China as an example, a fine mesh finite element model with a total of approximately 3.5 million degrees of freedom is established. The separate effects of the cantilever and integral dead loads on the static and dynamic responses of the dam are studied. The results demonstrate that the distribution and magnitude of the contraction joint opening width and maximum tensile stress are different under the two different dead load simplifications.

The proper description of finger-object contact state is critical to the analysis and control of multi-fingered hand grasping. At present, most studies assume that the finger-object contact state is invariable. However, in different stages of hand grasping, finger-object contact state is usually variable due to different contact factors, therefore, current finger-object contact models are not very suitable for describing it and the existing description and analysis of the hand grasping may be not appropriate. In this paper, we proposed a new method for describing and analyzing the multi-fingered hand grasping under various finger-object contact states, including a new finger-object contact model for describing the actual finger-object contact state, a grasp matrix for describing the hand grasping, and the condition number of the grasp matrix for analyzing the hand grasping. Taking a three-fingered hand grasping a sphere as an example, the hand grasping under four types of contact states was investigated. Simulations and experimental results both validated the effectiveness of the proposed method.

There are mainly two kinds of contact mechanics models for rough surfaces. One is based on the statistical characteristic parameters and depends on the measurement scale of rough surface topography. The other is based on the fractal parameters, which is independent of the measurement scale. However, most of the contact models for rough surfaces based on fractal theory use the size that is corresponding to the contact area of an asperity or the sample length as the base diameter of an asperity to describe the initial profile of asperities. As a result, the obtained deformation mechanism of asperities is not correct. To solve this problem, a new fractal characterization method for rough surfaces based on the fractal dimension $D$, fractal roughness $G$ and the highest asperity height is proposed, and then a fractal contact model independent of the measurement scale is established. The contact mechanism of asperities and variation trends of the real contact area and contact stiffness are discussed. When the contact pressure of the rough surface is less than its yield strength, its normal contact stiffness can be expressed as the first derivative of the contact pressure versus the normal compression, regardless of the deformation forms of asperities.

The joint surfaces in the computer numerically controlled (CNC) machines play a crucial role in transmitting load and energy in operations. In this paper, a new contact model between rough surfaces of a joint is proposed by considering the influence of surface waviness and substrate deformation. A contact model for a single asperity system is first established, in which the asperity and substrate deformations are calculated based on the Hertz theory. Then, it is extended to an entire rough surface by a statistical method, where the contact of rough surfaces is treated as the contact between a smooth waviness and a rough surface. The numerical results showed that when contact deformation is constant, the real contact area and the normal load of joint surfaces increase with increasing radius of the waviness peak while the normal load decreases with the increase of surface roughness. When a rough surface contains a coating layer or a surface film, the deformation of the joint surface has to consider both substrate deformation and asperity deformation. The substrate deformation will generate larger influence for a stiffer or harder coating. Compared with other models, the results obtained from the proposed model show better agreements with the experimental data.

In this paper, an extended Hertz model is proposed to predict the mechanical responses of the incompressible Mooney–Rivlin half-space under finite spherical indentation. The contact behaviors are systematically investigated through the axisymmetric finite element (FE) model using various constitutive parameter ratios. Based on the numerical results, the radius of contact zone is first derived by adopting the exact function of the indenter shape. A reliable prediction of contact force, for the incompressible neo-Hookean model, is then obtained by substituting newly modified contact radius into the original Hertz model. From this base, a correction factor, which characterizes the effect of constitutive parameter ratio, is introduced to predict the contact force, and the contact pressure distribution of the original Hertz’ formula is also extended for the incompressible Mooney–Rivlin half-space under spherical indentation up to the indenter radius. The extended Hertz model related to constitutive parameters is validated effectively through FE simulations and experimental indentation results under finite spherical indentation. On the contrary, when the indentation depth exceeds 10% of the indenter radius, the original Hertz model is unable to predict the strong effect of constitutive parameter ratio on the contact behaviors for the incompressible Mooney–Rivlin half-space.

This paper presents an open-source MATLAB/Simulink physics simulator for rigid-body articulated systems, including manipulators and floating-base robots. Thanks to MATLAB/Simulink features like MATLAB system classes and Simulink Function blocks, the presented simulator combines a programmatic and block-based approach, resulting in a flexible design in the sense that different parts, including its physics engine, robot-ground interaction model, and state evolution algorithm are simply accessible and editable. Moreover, through the use of Simulink dynamic mask blocks, the proposed simulator supports robot models integrating open-chain and closed-chain kinematics with any desired number of links interacting with the ground. This simulator can also integrate second-order actuator dynamics. Furthermore, the simulator benefits from a one-line installation and an easy-to-use Simulink interface.

A 3-D discrete element model with connective type was presented in this paper. Accordingly, a 3-D discrete element method code, which can calculate the transitional process from connective model (for continuum) to contact model (for non-continuum), was developed. The wave propagation in a 3-D concrete block under impact loading was numerically simulated, by using this code. Comparing its numerical results with those by LS-DYNA, the accuracy of this algorithm was presented. Moreover, the failure process of the concrete block under impact loading was demonstrated, which presented the basic dynamic transitional process from continuum to non-continuum. The two numerical examples prove that the new model and its code are powerful and efficient for simulating the dynamic failure problems accompanying with the transition from continuum to non-continuum. It also shows that the discrete element method will have widespread availability and perfect development prospect.