Improved Sliding Surface Search Method for Stability Analysis of Complex Slopes

AbstractThis article addressed an improved method of using random angle to generate random sliding surface. The search for two-dimensional random sliding surface was simplified into the search for the approximate curves generated by combination of delineation of different angles and vertical soil slices. Based on the searching method of a single curve sliding surface, a new method of generating random three-dimensional sliding surface by the generatrix and the directrix was proposed. The method of this article can be applied to stability analysis of two-dimensional and three-dimensional slopes. Comparison of different methods demonstrated the effectiveness of the method, and it is significant to research the random sliding surface without the assumptions of forms of sliding surface

Numerical Simulation of Discharge Process in the Single Screw Compressor

In the process of the single screw air compressor, the symmetrical grooves of the compressor are periodically connected with the discharge ports and the gas enters the discharge chamber or flows back from chamber, generating gas pulsation. The gas pulsation increases the flowing loss to bring additional energy loss, meanwhile the gas pulsation is the one of main reasons for the generation of vibration and noise. The thermodynamic model of the compression chamber and the discharge chamber of a single screw air compressor is established in this paper taking the discharge chamber structure and the flow resistance into consideration. The working process in discharge chamber is simulated base on the thermodynamic model. In addition, the influence of speed and back pressure on the pressure in the discharge chamber is investigated in detail. The analysis results provide a basis for optimum design of structure and reduction of vibration and noise

Simulation of the Superheated Water Expansion Process in a Cylinder with Moving Piston

The Trilateral cycle has attracted more and more attentions because of its better temperature profiles matching in the heater compared to conventional heat recovery cycles, such as the Organic Rankine Cycle and the Kalina Cycle. However, the actual fundamentals of the two-phase expansion process have not been clarified, especially, the evolution mechanisms of the evaporating rate and the degree of superheat during the expansion process are indistinct. In the present study, two-phase expansion process of superheated water in a cylinder with moving piston was analyzed. A model was proposed to calculate the evaporating rate and the degree of superheat of liquid water. A semiempirical Nusselt number was adopted to solve the energy conservation equations. It was shown that the degree of superheat of liquid water was increased rapidly to the maximum at the beginning of the expansion process and then was decreased continuously. The degree of superheat was almost equal to 0 at the end of the expansion process. The simulation results also showed a complex evolution profile of the evaporating rate during the expansion process. As a whole, the evaporating rate was increased from 0 to the maximum, and then it was decreased to 0 at the end of the expansion process. This situation is similar to the experimental results in the published literature. The evaporating rate appeared a transient dropping process at the beginning of the expansion. It was considered that this result was associated with the rapid decline of the degree of superheat. Meanwhile, there were two or three significant inflection points on the evolution profile. From the model prediction, it was concluded that the evaporating rate may be related to the degree of superheat of liquid water, the piston velocity and the mass of liquid water in the cylinder

Research on Image Retrieval Optimization Based on Eye Movement Experiment Data

Satisfying a user's actual underlying needs in the image retrieval process is a difficult challenge facing image retrieval technology. The aim of this study is to improve the performance of a retrieval system and provide users with optimized search results using the feedback of eye movement. We analyzed the eye movement signals of the user’s image retrieval process from cognitive and mathematical perspectives. Data collected for 25 designers in eye tracking experiments were used to train and evaluate the model. In statistical analysis, eight eye movement features were statistically significantly different between selected and unselected groups of images (p < 0.05). An optimal selection of input features resulted in overall accuracy of the support vector machine prediction model of 87.16%. Judging the user’s requirements in the image retrieval process through eye movement behaviors was shown to be effective