Applied Mechanics and Materials Vols. 157-158

Abstract: For a palletizing robot, based on analysis of structural and force,taking the theory of D'Alembert to transform the instantaneous inertial force system into a static system and the Kineto-static mathematical model for the robots is established through the method of Kineto-static. At last, via solving the Kineto-static mathematical model by use of the Matlab，the model is verified by calculating and analysing an example. This model is applicable to dynamic analysis on the robots with similar configuration and the results based on the parameter variation is also applicable to this kind of robot’s design, checking, and kinetic control.

Abstract: Ultrasonic wave transmitted in the plate is called Lamb wave. The dispersion characteristic of Lamb wave makes it very complicated to be used in material Nondestructive Testing (NDT). In order to solve this problem, the analysis of frequency-dispersion characteristic of Lamb wave is made in this paper, and the dispersion curves of the Lamb wave in specific plate are plotted, then the physical propagation model of Lamb wave is established. Under the analysis of FFT, the expressions of the Lamb wave in specific plate are obtained. By combining with the dispersion characteristic of the Lamb wave, the changes of waveform in different propagation distances are simulated. With the deep researches of new algorithms, Lamb wave will be applied in wider area.

Abstract: Generators are of different importance to the system in terns of voltage stability. It is extremely vital to research generators’ impacts on the voltage stability. In this paper, the theory of the normal forms of diffeomorphism is used to analyze the power flow equations. By this method, the nonlinearity of power systems can be taken into consideration. Therefore, the impact of generators can be measured with more accuracy even for the cases in which the system is characterized with strong nonlinearity. The IEEE 14-bus test system is used as a case study. The results show that it ranks the generators with more accuracy than the traditional linear method.

Abstract: The purpose of this study is to improve the problem of vibration which occurs in a running reciprocating compressor, by determining an optimal crankshaft counterweight and narrowing the movement trajectory of the crankshaft connecting rod mechanism. An analytical solution method is applied to satisfy the requirements for vibration reduction. Use of finite element software is to simulate the modality and deformation of crankshaft under various conditions of counterweight. Modal testing shows a difference of less than 6 % between the simulation and the experimental results. After the crankshaft counterweight is machined and installed, the new crankshaft is able to reduce compressor vibrations from 32 mm/s down to 15.8 mm/s and noise reduction of 3 dB. This study can provide information pertaining to the design process and assessment to any future new compressor designs.

Abstract: The improved equations of motion for a friction-engaged brake system have been newly derived on the basis of the assumed mode method and frictional damping. The equations of motion with a finite element model were constructed by a set of vibration modes found from FE modal analysis on all system components. Consequently, the modal information of system components are combined with equations of motion derived from the analytical model. Numerical analysis showed the mode which was unstable in an undamped case became stable in a damped case.

Abstract: Coverage has recently emerged as a premier research topic. This paper addresses the problem of monitoring of targets with hybrid network, which is composed of some static sensors randomly deployed in the sensing area and some mobile sensors deployed in the edge. Probability model is used to find all the maximal breach paths. The nearest mobile nodes to the maximal breach paths will move to the maximal breach path with certain speed, to ensure that the target can be detected within the monitoring area. Algorithm is presented for using mobile nodes to enhance barrier coverage. Simulation confirms the efficiency of our moving strategy.

Abstract: Human face three-dimensional (3D) reconstruction is a challenging problem. In this paper, we propose a human face fast- 3D- reconstruction method based on image processing with a single image. Shape from shading (SFS) is chosen to reconstruct the human face. First, SFS theory is introduced. It has the advantage of fast 3D reconstruction and only need a single image. Secondly, because the noise will affect the 3D reconstruction result greatly, wavelet transform and wavelet packet transform are introduced and used in image denoising respectively. The experiment has shown that the method based on wavelet transform produces the best denoising result than wavelet packet transform. At last, a human face 3D reconstruction algorithm based on a single image is proposed. The experimental results show that a human face 3D model can be reconstructed in fast by proposed algorithm.

Abstract: Medical image segmentation can be divided into two categories: one is the region of interest (ROI) identification; the other is the description of the integrity and the extraction of interest region. The emergence of the level set method greatly promoted the development of medical image segmentation. This paper studies three different level set segmentation algorithm to achieve the effective segmentation for brain gray matter and white matter of MRI image.

Abstract: Reactive power plays a key role in the power systems operation and stability. By using theory of normal forms of diffeomorphism, this paper proposes an index of bus voltage nonlinear factor, used to measure the effect of buses to the steady-state voltage stability. In order to verify the effectiveness of the proposed method, case studies are performed using the New England 39-bus power system. At the view of steady-state voltage stability enhancement, the results show that the bus voltage nonlinear factor is an effective index. It can give the correct indication of reactive power compensation dispatch.

Abstract: Bulge deformation is an important factor that causes inner crack and declines the quality for slab. This has a significant genetic phenomenon in continuous casting process. In order to explain this feature, a two-dimensional FEM model for slab that includes viscoelastic and dynamic characteristic has been built. Positive creep and reverse creep were introduced to explain this mechanism. Roll pitch, shell characteristic, slab withdrawing speed and other process parameters that influence bulge’s genetic level are discussed. A nonlinear equation was suggested to describe the relationships between these factors and genetic level of bulge.