Key Engineering Materials Vols. 460-461

Abstract: Laser tube bending is a spring-back-free noncontact forming method that has received considerable attention in recent years. Compared to mechanical bending, no hard tooling, dies, or external force is used in laser bending, thus the cost is greatly reduced for small-batch production and prototyping. Some quality issues, such as cross sectional distortion and intrados protrusion exist in laser bending and have growing tendency when the tube’s wall being thinner. This paper investigates the effects of process parameters on the deformation of thin wall tube through numerical simulations and experiments. The dimensions of the tube analyzed are 32 mm in outer diameter and 0.48mm in wall thickness. A three-dimensional transient thermo-mechanical analysis using the finite element method is carried out to simulate the laser bending process with some results validated by experiments. The effects of process parameters on the deformation of thin wall tubes are discussed in detail.

Abstract: The knowledge of the flow behavior of metals during hot deformation is of great importance in determining the optimum forming conditions. In this paper, the flow stress of 00Cr17Ni14Mo2 (ANSI 316L) austenitic stainless steel in elevated temperature is measured with compression deformation tests. The temperatures at which the steel is compressed are 800-1100°C with strain rates of 0.01-1s-1. A mathematical regression model is proposed to describe the flow stress and the validation of the model is conducted also. The proposed model can be used to predict the corresponding flow stress-strain response of 00Cr17Ni14Mo2 stainless steel in elevated temperature for the numerical simulation and design of forming process.

Abstract: In this paper a feasible method is proposed for solving a class of mathematical problems in manufacturing system and production system. By utilizing linearization technique the relaxation programming problem about the original problem is constructed. The proposed branch and bound algorithm is convergent to the global minimum of original problem through the successive refinement linear relaxation of the feasible region of objective function and solutions of a series of relaxation linear programming problem. And large number of experiments results show feasibility of presented method.

Abstract: For the purpose of reduce the complicated process of H.264/AVC standard, the overall coding flow is studied, and some of the key technolies are discussed in the front part of this thesis. An algorithm for determining the distortion for different data partitions in H.264/AVC is proposed. A low-pass filter is implemented for each macroblock; after the macroblock is smoothed by this filter we compare the result of the filtered macroblock with the original data and generate the difference between them. Then the basic candidate-mode class is determined based on the difference, and the further mode decision can be made within this sub-class. So that the number of candidate modes is reduced, and the complexity of I-frame mode decision process is reduced.

Abstract: The crude fat content in fish feeds was determined using mid-infrared transmittance spectroscopy and chemometrics fast and non-destructively. A total of 225 samples were prepared for spectra collecting from a FT/IR-4000 Fourier Transform Infrared Spectrometer (400-4000cm-1). Principal component analysis (PCA) was carried out and spectral data were compressed into several new variables, which can explain the most variance of original spectra. The first six PCs were used as inputs of back-propagation neural network (BPNN) and least squares-support vector machine (LS-SVM) to create the calibration models. Compared with BPNN, a slightly better prediction precision was achieved based on LS-SVM with correlation coefficient (R) = 0.9757 and root mean square error for prediction (RMSEP) = 0.2579. The overall results indicated that mid-infrared spectroscopy incorporated to chemometrics was promising for the accurate assessment of crude fat content in fish feeds.

Abstract: This article first introduced the survey of mechanical fault diagnosis technology development and the data mining technology theory. Then its application situation at present and the main questions that exist are elaborated. Its development trend is analyzed. The application feasibility of using data mining technology in mechanical fault diagnosis is discussed. Next, the naissance, the development and the future development tendency of data mining technology are introduced. The four algorithms are analyzed and the framework is built too. Intelligent Diagnosis is a major development direction of the fault diagnosis. Knowledge acquisition is the bottleneck of Intelligent Diagnosis development. It comprehensive use of many kinds of advanced technology, discover valuable and hidden knowledge from the large amounts of data mining.

Abstract: In order to eliminate the chattering phenomena caused by conventional sliding mode control (SMC) method in magnetic bearing system control, this paper proposes a variable rate reaching law approach based sliding mode controller to achieve higher system stability and robustness. In this control law, system states’ normal numbers are brought in to automatic adjust the gain of the switching control part of SMC. The controller output amplitude of chattering can be progressively damped, and the system will converge to zero asymptotically. The system stability is proved by Laypunov theory, and the prerequisite of control law parameters design is deduced out. Simulation results show that the proposed SMC control method has effectiveness in dynamic suspension position tracking performance and obtaining system robustness.

Abstract: The multimedia communication based on IP network has been a popular direction. The problems of the multimedia communication in current IP network are analyzed. The transfer specialty of multimedia, key technologies and primary specialty of IPv6 are introduced. Finally, a multimedia communication system based on IPv6 is discussed.

Abstract: This paper presents adiabatic flip-flops operating on near-threshold supply voltages. The near-threshold adiabatic flip-flops and sequential circuits are realized with improved CAL (Clocked Adiabatic Logic) circuits using a single-phase power clock. An auxiliary clock generator is used to obtain the non-overlap sinusoidal auxiliary signal pair. A near-threshold mode-10 counter is implemented. All circuits are simulated using Predictive Technology Model (PTM) 45nm process. The near-threshold adiabatic circuits attain large energy savings over a wide range of frequencies, as compared with conventional static CMOS logic circuits.