Advanced Materials Research Vols. 706-708

Abstract: According to the multivariable coupling、 large time delay, non-linearity and time-varying and other difficulties of circulating fluidized bed boiler combustion system, a kind of control technology based on neural network to circulating fluidized bed boiler combustion system was presented. Actual parameter data of a paper mill in Kunming and neural network control principle were used in the establishment of a circulating fluidized bed boiler combustion system mathematical model and modified BP neural network algorithm training. Results of MATLAB simulation show that boiler combustion system control precision was effectively improved and good effects in production and application were got.

Abstract: Multiple degree-of-freedom compliant mechanisms are widely used in the fields of micro-positioning and micro-manipulation. This paper deals with multiobjective topology optimization of multi-input and multi-output compliant mechanisms undergoing large deformation. The objective function is defined by the minimum compliance and maximum geometric advantage to meet both stiffness and flexibility requirements. The suppression strategy of input and output coupling terms is studied and the expression of the output coupling terms is further developed. The weighted sum of the conflicting objectives resulting from the norm method is used to generate the optimal compromise solutions, and the decision function is set to select the preferred solution. Geometrically nonlinear mechanism response is calculated using the Total-Lagrange finite element formulation and the equilibrium is found using an incremental scheme combined with Newton-Raphson iterations. The solid isotropic material with penalization approach is used in design of compliant mechanisms. The sensitivities of the objective functions are found with the adjoint method and the optimization problem is solved using the Method of Moving Asymptotes. Numerical examples of multiple inputs and outputs are presented to show the validity of the new method. Simulation results show that the compliant mechanisms can be deformed in the desirable manner and the coupling output displacements are suppressed significantly by using the presented method.

Abstract: Electromechanical device driven by motor plays a crucial role in the operation of modern industry. A reliable time series predictor can be a very useful tool in the field of Condition-Based Maintenance (CBM) to forecast the behavior of motor. This paper presents an approach to predict the operating conditions of motor based on support vector machine (SVM). In order to improve the accuracy of prediction, a multivariate SVM predictor is built using multi-source multi-attribute information for time series prediction. The advantages of the multivariate SVM predictor is verified by empirical results derived from a real system of motor in power plant.

Abstract: Iron loss will be rapidly increased when the permanent magnet iron core synchronous motor runs at a high speed, which makes the motor produce so much heat that causes low efficiency of the motor and even burns out the motor. The iron-core-free permanent magnet synchronous motor remedies this defect and has a high efficiency at high speed. This article makes a comparative analysis on the iron-core-free permanent magnet synchronous motor torque density with different slot engagement classifications. The paper puts forward an optimized model of permanent magnet synchronous motor without the iron core. The technology of the permanent magnet synchronous motor without iron core is studied based on this model which provides a method to design and manufacture the iron-core-free permanent magnet synchronous motor.

Abstract: A new polarized scattering instrument is presented in this paper. The finite element analysis has been used to examine the static performances of this instrument so as to capture necessary structural characteristics. Consider the structural volume and tip deflection as objectives, a double-loop of topological and parametric optimization has been developed that result in the optimum material distribution and volume fraction. Such an optimum structure is further modified to a solid model for the optimum product design. The final results show that the tip deflection and material volume can evidently be improved consequently. The presented process of mechanical design skill can provide for creative mechanical engineering application.

Abstract: Based on the research of the law of performance of electrical and mechanical equipments, the characteristics of highway electromechanical system is studied. According to current quality inspection and evaluation standards, the hierarchy criteria system is deduced, and the importance degree of each criterion is calculated according to the responses on the question form by Delphi method. By membership functions, each criterion is given the weight which is normalized as the importance degree for the hierarchy level. Then, the fuzzy comprehensive assessment model is established with judgment matrix.

Abstract: In this research the fabrication of carbon aerogel is reported. nanopore carbon aerogels were prepared via a sol-gel process with resorcinol and formaldehyde (RF) aerogels,which were cost-effectively manufacture form Rf wet gels by an ambient drying technique instead of conventional supercritical drying. The key of the work is to fabricate carbon aerogels with controllable nanopore structure, which means sharp pore size distribution and extremely high surface area.The influence of preparation condition of carbon aerogels was studied by scanning electron microscope and Micropore Physisorption Analyzer. The BET surface of the carbon aerogels are from 749m²/g to 1156m²/g .The size of the carbon nanoparticles are in the range of 20nm~40nm. The micro-pore volume and bore diameter can be controlled by gelation conditions such as RF mass fraction.

Abstract: The stability conditions of 1/4 vehicle active suspension with time-delay were deduced by the theory of Routh-Hurwitz stability criterion and the critical instability time-delay was discussed and calculated. Compared with PID control method of without time-delay the simulation results show that when the critical time-delay is 0.153s, the amplitude range and its root mean square value of spring load quality vertical acceleration were increased 1.2 times or so and the system was being on the critical stability. The calculation and simulation results proved that the theory of Routh-Hurwitz stability criterion laid a foundation for the design and instability mechanism of active suspension.

Abstract: Lamb Wave testing based on PZT has features that are sensitive to plate thickness direction, low cost and suitable for long distance. It has received more and more attention. In this thesis, the principle of Lamb Wave testing method is introduced, research status and image processing technology is summarized, and future work is outlook.

Abstract: In this paper, we investigate an acoustic remote control technology through the annulus channel in an oil-well. To establish a reliable communication, we first evaluated the acoustic charateristic of the aunnulus channel through field experiments. Then, a remote control system was implemented with a ground equipment serving as an acoustic source, and an underground equipment used as a receiver. A demonstrative experiment, in which we succeded in remoting an intelligent valve over 1257 m, has been presented to verify the proposed technology.