Applied Mechanics and Materials Vols. 130-134

Abstract: The methods and theories about reducing energy consumption of buildings are some of the most popular topics for green buildings research recently. Vapor compression chiller, the largest proportion of building energy consumption, as the design and running characteristics, work at part load for most of the time. To improve the energy efficiency at part load, this paper details some efforts to develop a linear MIMO model of a vapor compression system suitable for MPC control method. Experiments show that the controller can simultaneously achieve satisfactory transient response in the evaporating temperature and superheat, and improve energy efficiency at steady state.

Abstract: Oriented filters are useful in many computer vision and image processing tasks. It is a kind of oriented filters, rotated very efficiently by taking a suitable linear combination of basis filters. Local steerable feature (LSF), which captures local structure corresponding to any orientation, is distinctive enough to provide useful identity orientation information. This paper investigates novel LSF-guided active contour approach for texture segmentation. The steerable filters are first employed to produce a new energy image, then, the active contour proposed by Chan-Vese (ACWE) is applied to the energy image. These active contours combine the advantages of both the LSF texture representation and the ACWE model, and yield high quality texture segmentation. The performance of the algorithm on some test images is presented and analyzed.

Abstract: This paper proposes a new analytical model of manufacturing system with two parallel machine workstations. The machines in the system are non-identical unreliable machines, and the processing times, failure times and repair times of the machines are assumed to be exponentially distributed. In this paper we for the first time give an exact model of two workstation parallel machine system. Case studies show the accuracy of the proposed model.

Abstract: As to spiral groove grinding, convertionally was based on envelope theory, a formed wheel was needed to be designed and manufactured, and then this wheel was used to grind the specified spiral groove. This paper tried to find the other way to manufacture the specified spiral groove with common disc wheel or dish wheels. A generic model for groove grinding is presented in this paper. With the model, the groove geometries can be calculated under certain grinding parameters. The relations between the grinding parameter and groove geometries were studied numreically. A test was done and the results proved the model is correct. This technology make the spiral groove virtual machining possible. The technology is also a real DFM (Design For Manufacture), because the design process for spiral groove is the process for selecting manufacure parameters.

Abstract: This paper presents the faster calculating models of temperature and thermal stress in a rotor based on two-dimensional axis-symmetry thermal conduction and thermo-elastic theory. The models can deal with nonlinear factors caused by temperature-dependant properties using modified Newton-Raphson iterative method. An example has been given to compare the results calculated by the models with those calculated by finite element method. It is shown that the analytical models gained have high accuracy. The iterative models can be used for online monitoring and control of turbine.

Abstract: Much more investigation is done in the low speed operation of IM. High-speed operation is rarely paid attention; since it is assumed that the IM would work successfully in that area. However, the high-speed operation of IM with conventional feedback designing behaves not so well and presents oscillation situation, due to inappropriate placement of eigenvalues of flux observer and deterioration of speed adaptation mechanism. Correspondingly, considering the saturation effect of main flux, this paper proposes a new feedback designing method and improved speed adaptation mechanism.

Abstract: Owing to the tamping mechanism of paving machines, the shocks towards flatiron-box are produced by compound motion of tamping beam. This significantly influences the road paving quality. In this paper, the dynamics model of double-tamper mechanism is established and the vibration process is simulated by the numerical analysis software—Matlab. Through the analysis of double-tamper mechanism, we can get the impact regularity of the vibrating beam inertia force and moment of inertia as a result of the vibration frequency and amplitude. It provides a reference for the design of double-tamper mechanism for asphalt paver and the adjustment of construction parameters.

Abstract: Aiming at complex features of the fault rotating machinery such as nonstationary and nonlinearity, a new method for fault diagnosis based on multi-fractal was introduced. The vibration signals firstly are analyzed by multi-fractal theory and have multi-fractal characteristics. Then the area of multi-fractal spectrum S and the entropy of multi-fractal spectrum Hm were extracted as new criterions to diagnose machinery faults. Results of experimental analysis indicate that the method is effective and it provides a new way in fault diagnosis of rotating machinery.

Abstract: Vapor compression chiller, the largest proportion of building energy consumption as the design and running characteristics, work at part load for most of the time. To improve the energy efficiency at part load, this thesis details some efforts to develop a dynamic model of a vapor compressor system suitable for optimal control design purpose. It present the model of high pressure liquid receiver which is important for the mass balance of the whole system and make sure it operated in a set-point designed. Additional experiments were also performed to verify the precision of the model.

Abstract: The load rotational moment and power of a centrifuge with rotational arms (CWRA) consist of aerodynamic, inertial and frictional rotational moments and related powers, respectively. The chosen electromotor based on previous calculations cannot accurately provide proper moment and power for dynamic CWRAs. In this paper, the maximum load rotational moment and maximum load power of a CWRA were formulated, a method to calculate the rating power of its driving electromotor was suggested, and an analytical computational example was performed. The results show that the present method is much more accurate than previous ones.