Applied Mechanics and Materials Vols. 201-202

Abstract: Based on the theory and method of innovative design aided by patent knowledge, this paper analyzes the existing patents about pneumatic pump reversing devices and the other patents, and establishes the library of principles and structures which can achieve reversing function. As there are many shortcomings of existing pneumatic pump reversing devices such as a lot of collisions, big noise and difficult to manufacture, based on the principles and structures which can achieve reversing function, this paper proposes two new pneumatic pump reversing devices to help solve these problems. Compared with the existing pneumatic pumps, the new devices have many advantages, such as simpler structure, less collision, less noise and less cost.

Abstract: Mechanical rotation-mirror symmetry is grouped by rotation symmetry and mirror symmetry, and belongs to mechanical static structure symmetry. Collecting and Analyzing a lot of rotation-mirror symmetric instances, and referring to the researches on concept systems of rotation symmetry and mirror symmetry, the concept system of rotation-mirror symmetry was established. The concept system is classified by discrete mirror and continuous mirror rotation-mirror symmetry, unidirectional rotation and bidirectional rotation rotation-mirror symmetry, directed rotation and deflecting rotation rotation-mirror symmetry, entire rotation and partial rotation rotation-mirror symmetry. The concept system can completely contain all kinds of existence of rotation-mirror symmetry in mechanical systems.

Abstract: Pneumatic pump use compressed gas as power source, outputting straight reciprocating motion. It is widely applied in high pressure airless spray machine. Reversing mechanism is the core component of pneumatic pump. According to the different ways of distributing and reversing gas, pneumatic pump reversing mechanism can be divided into two major categories of pneumatic control type and mechanical type. We summarize the history of the development and the present situation of research and compare various reversing mechanisms in the realization principle, design of structure, manufacturing, vibration noise and cost of production etc. Then we put forward the direction of its research and development, providing theoretical basis for the subsequent development of high quality and efficient pneumatic pump.

Abstract: Clamping unit is an important component of injection molding machine. The clamping force and the clamping speed of clamping unit not only effect on the quality of molding products, but also determine the cyclic number. The large force amplification and large stroke ratio can reduce energy consumption and improve the productive efficiency. In this article, force amplification ratio and stroke ratio were used as the optimization goals. Non-dominated sorting genetic algorithm was used as the optimization method. The optimization result was better than the original design. So this article provides a reference for the same or similar product’s optimization.

Abstract: High intensity focused ultrasound (HIFU) is the fourth brand-new and efficient means to cure tumour acknowledged by the medical field. Study of ultrasonic transducer is a core part of HIFU technique, In order to ensure reliability and safety of treatment, it is a key for HIFU technique to realize accurate focusing of ultrasonic energy. In the thesis, ultrasonic focusing method, studies of current situations of cell and multiplex array focusing transducers and their existing problems are illustrated based on analyzing challenges faced by HIFU treatment at present. This study suggested that phased array was theoretically easy for realizing accurate control of computer， however, unbeneficial factors and engineering technical problems still exist; How to promote intensity of the focal spot of cell array focusing transducer, enlarge scope of the focal area and improve control way of the focal spot was a bottleneck problem for publicizing and applying cell array focusing transducer and one of urgent research topics for ensuring curative effect of HIFU and avoiding heat damages.

Abstract: In order to obtain good static and dynamic characteristics of the 2-DOF micro-positional stage, improved design of developed stage were done. First, the part of displacement coupling for the stage was improved, which making the stage only have linear displacement at driving direction; Second, in order to acquire the highest natural frequency under the condition of given output displacement, micro-positional stage was designed by using the size optimization method. Finally, the static and dynamic characteristics of the stage were analyzed by the finite element software ANSYS. The finite element results show that: the stage completely eliminates the displacement coupling after improving design; under the condition of given 30 μm output displacement, natural frequency reaches 1.86 kHz.

Abstract: The material of pillow has influenced on body pressure distribution and human comfort. This paper studied the relationship between the characteristic of pillow materials and sleeping comfort in supine position through head, neck, back pressure distribution system and subjective evaluation on ergonomics methods. This paper selected chemical fiber, buckwheat, latex, memory foam, inflatable cushion, traditional Chinese medicine / tea and pearl cotton for experimental materials. The results showed that the pillows with memory foam and latex was better in pressure distribution and subjective evaluation. The pillow with traditional Chinese medicine / tea and inflatable cushion had lower elasticity and poorer sleeping comfort. The buckwheat pillow can relieve neck fatigue. This study results have important reference value to the material of pillow and comfort pillow design.

Abstract: The Aero-Engine Is the Heart of an Aircraft and Critical to the Flight Safety and Economy, Health Management in Total Life Cycle for Aero-Engines Is an Effective Way and Is Popularly Employed to Balance the Economy and Safety. however, it Is Difficult to Make Appropriate Health Management Strategies for a Complex System, such as Aero-Engines. Firstly the Uncertainty Source of Fault Diagnosis and Prognosis System Is Explored. then the Primary Uncertainty Sources Including Condition Information, Monitoring and Detection Approaches, Signal Detection, Remaining Lifetime Prediction and Maintenance Strategy-Making, Are Analyzed in this Context. the Corresponding Tactics for Reducing Uncertainty Are Proposed in the Paper, which Provides Essential References for Assisting the Design for Health Management System.

Abstract: The tuning for Oracle database system is vital to the normal running of the whole system, but it is a complicated work. SQL statement tuning is a very critical aspect of database performance tuning. It is an inherently complex activity requiring a high level of expertise in several domains: query optimization, to improve the execution plan selected by the query optimizer, access design to identify missing access structures and SQL design to restructure and simplify the text of a badly written SQL statement. In this paper, the author analyzes the execution procedure of oracle optimizer, and researches how to improve the oracle database query performance in MES.