Applied Mechanics and Materials Vols. 201-202

Abstract: Light propagation in the air is easily affected by the environment. Shaft bending vibration and torsional vibration are needed to be measured at the same time. The different vibration state are coupled each other. For these reasons, it is necessary to design the optical fiber laser Doppler measurement system and develop the integrated optical fiber system, which is in favor of various vibration modes decoupling and can improve the signal-to-noise ratio. The double parallel beam differential scheme is adopted in the torsional vibration measurement, which the light exposed in the air is coupled into the optical fiber. The optical fiber heterodyne Doppler interference measuring method is adopted in the bending vibration measurement. The laser Doppler vibration measurement technology is applied to a rotating shaft vibration measurement. Comprehensive measuring technology is developed, which can simultaneously measure bending vibration, torsional vibration and the rotation speed of shaft.

Abstract: Configuration of a molten pool is related to the laser welding quality. Analyzing the configuration of a molten pool is important to monitor the laser welding process. This paper proposes a method of segmentation of a molten pool and its shadow during high power disk laser welding, consequently provides the groundwork for reconstruction of the molten pool and analysis of welding quality. Subsection linear stretching histogram equalization was applied to enhance the contrast of the original images firstly, and then edge detection was used to highlight the edges. After that we used the morphology filtering method to produce the segmentation mask, and then combined the mask with the original images to get the final segmentation results. Also, the proposed method was compared with other traditional methods. The experimental results showed that our method not only could give better segmentation results and process large quantities images automatically, but also overcame the less-segmentation problems of traditional methods.

Abstract: The multi-level converter is one of the focuses in the current high-voltage high-power field of power conversion, and is found widely application in high power drive system. It generated so far for nearly three decades of history. During this period a large number of multi-level topology appeared, there are three most commonly used, which are diode clamped, capacitor and cascaded H-bridge. In this paper, the development of the multi-level converter is reviewed. The structure of three multi-level converter topologies are given, and then their advantages and disadvantages are given by analyzing and comparing their characteristics. Finally, a new modular multi-level converter (MMC) is introduced which is one of research focus of multi-level converter field at present. Its structure and working principle are described in detail. Multi-level converters will continue to be developed to meet the demand of high-voltage and high power applications.

Abstract: This paper provides a kind of roller maintain machine. It introduced the structure and the working principle of the roller disassembly and assembly machine. According to the work requirements, selected the PLC Toshiba's F1-20MR，to realize the switching sequence control function. Analyzed machine's work flow, Designed the PLC control program. Point out the advantage that using PLC replaced the original relay logic control systems: flexible application and good generality, high reliability and environmental adaptability; the program is simple to grasp easy.

Abstract: This paper analyzes the interactions between lighting and the human-product-environment system from an ergonomics perspective. Studies on the effect of the foreground and background lighting on the atmosphere perception was conducted in an experiment room, which specifically to improve the interaction between the lighting and customers. Data from the experiment shows that the background lighting characteristics do have different effects on the atmosphere perception on the customers. Firstly, different background light settings will have significant effect on the words “active-dull”, “private-public”, “formal- informal”, “warm-cold”; secondly, the beam angle of the foreground lighting will play effect upon the atmosphere of “warm- cold”; thirdly, the brightness of the background lighting will affect the perception of the words like “active-dull”, “private- public”, “formal- informal” and “relax-tense”; finally, different color temperatures of the background lighting will play significant effect on the sense of “warm- cold” and “expensive- inexpensive”.

Abstract: Numerical simulation of shell-and-tube heat exchangers with novel helical baffles was carried out by using commercial codes to study shell-side flow and heat transfer characteristics. The results show that compared with shell-and-tube heat exchangers with conventional helical baffles, the ones with novel helical baffles can efficiently reduce the leakage from triangle zone so that the distributions of both the velocity field and heat transfer on tubes are more uniform. The comparison of comprehensive performance which is evaluated by heat transfer coefficient per unit pressure drop between conventional helical baffles and novel ones indicates that the latter performs better.

Abstract: Currently the BP networks which used in friction welding defect recognition existents the problem of slow convergence and easy to fall into local optimum. This text will introduce the germ arithmetic into the BP network to turn a beginning to start the power value, putting forward the improvement BP network of the blemish identify. Pass to verify the blemish signal of the some GH4169 heat metal alloys detected by a super voice C, which expresses that the method makes blemish qualitative analysis classification acquired higher accuracy, and it can lower artificial and subjective factor consumedly to the influence that the blemish identify.

Abstract: The user's preferences and views make a profound impaction on the public acceptance of the product. Both can be expressed through the study of product semantic. This article describes the application of semantic differential method to establishment and analysis the laptop bag products semantic space. Through the collection of 60 subjects’ evaluation of 8 laptop bags, the semantic universe is reduced to a collection of 25 adjectives semantic by using of semantic differential method. Semantic axis are defined the main component factor. The influence of subjects’ number in the semantic evaluation results is also studied. The establishment of the semantic space is the first step for introducing emotional performance in products design and interaction, which would increase the success probability of products. This statistical measurement help make decisions in terms of design expression.

Abstract: The traditional PID regulator can get a satisfactory control effect in many situations. But because of the welded pipe servo cutting system characteristics with not fixed the parameter, variable, strong nonlinear and coupling complex, it is difficult to obtain ideal response in different time, and it is also hard to adapt changes in the environment and the uncertainty of the system. In allusion to the defect of the traditional PID regulator in the welded pipe cutting machine, it is put forward the parameter self-setting fuzzy PID adjustment method and a kind of fuzzy reasoning control rule in this paper. According to the rule, a welded pipe cutting machine control system mathematical model is established and numerical simulation of tailing after the given order jump curve in adaptive fuzzy PID regulator is finished. The simulation results show that: the system response speed is faster than before, the system adjusting precision and stability become well. All of this is hard to realize from traditional PID.

Abstract: This paper describes a method about curves interpolation. Linear interpolation and circular interpolation feature is often used in the NC system, however, the processing of complex curves have not correspondence interpolation instructions, but most of the NC system have function feature to achieve the processing of the complex curves. Here analyze how to establish the parameters equation of the cam profile, and how to compilate the corresponding processing programs with the function feature of NC system. Point out using the numerical control system's function may complete all kind of curve interpolation, that the curve has the definite functional relations. The establishment equation is the key using linear interpolation command G01 to realize curve processing. Using Variable function of the numerical control system to prepare CNC machining macro program, the programming is very convenient.