Advanced Materials Research Vols. 712-715

Abstract: The multislice spiral computed tomography (MSCT) is famous for the small radiation,large volume scanning and quickly reconstruction, and it becomes the first choice in clinical examination. The upper slicing system is the main components of the optical system in MSCT. This paper focuses on the design of upper slicing slice system and its precision analysis to improve the precision of imaging. The error of slice thickness and ray center by bearings, screw and control system is analyzed and tested. Improving the precision of the upper slicing system contributes to determine the appropriate treatment methods to improve the success rate of treatment.

Abstract: The thin-walled components of aero industries in general have complex structures whose machining accuracy is very difficult to be guaranteed because of the weak rigidness. To resolve the problem of the thin-walled disc clamping deformation, one novel clamping approach with flexible clamping capability is proposed in this paper. The surface morphology measuring systems (SMMS) and fast servo cutting system (FSCS) are developed, and its microstructure morphology duplicating accuracy is experimentally proved to be about 1μm under working environment. The clamping deformation is clarified weaker via flexible clamping approach which makes thin-walled disc morphology uniformly adaptive to the clamp.

Abstract: The optical properties of micro-structure surface mold roller in the field of optics, machinery and electronics, biomedical and defense sectors are showing an increasingly important application value and broad application prospects. There is still no more mature method to machining ultra-precision large-size optical V-groove mold roller, and the roller surface treatment technology cant meet the technical requirements of the field of optical applications. This article takes advantage of ultra-precision diamond turning to machining V-groove structure on nickel-phosphorus plating steel roller by spiral cutting method. The helix angle of the mold roller was designed 0.9", which meet the requirements of the experimental error, while using a nickel-phosphorus alloy coating can eliminate the secondary polishing process and achieve a cost-efficient ultra-precision machining. Analyzed the processed tool wear, high-temperature graphitization and micro-chipping were the main reason for tool wear.

Abstract: In this paper, a thermal error analysis and compensation method for a high precision aspheric measuring platform driven by a linear motor system is presented. After analyzing the heat source of thermal deformation, the thermal deformation of guide is selected to be object, and the thermal analysis method of guide in heat balance state is proposed. According to the motor temperature at different positions, the thermal error curve of guide is obtained through simulation. Modeling the global positioning error of measuring platform and the compensation model of thermal error using polynomial fitting, the thermal error compensation experiments is implemented by applying compensation system of measuring platform's controller. The experimental results show that the maximum positioning error in heat balance state is reduced from 1.5μm to 0.7μm, which verify the validity of thermal error compensation model.

Abstract: Blade is one of the most important components of an aero engine; its geometric shape should be inspected carefully in the production stage to ensure that it satisfies the tolerance specification. Blending and torsion deformation are basic items of blade geometric shape inspection. Coordinate Measurement Machine (CMM) has been widely used to perform the blade geometric shape measurement. Some sampling strategies for blade CMM measurement are discussed and one kind of blade blending and torsion deformation calculation method considering the CMM probe radius compensation is presented. Experiments based on simulation data and real measurement data are performed to verify the adopted sampling strategy and deformation calculation method.

Abstract: In general, the sound speed in air depends on the air characteristics, such as temperature, pressure, humidity, gas composition, and air turbulence. It has direct influence on performance of ultrasonic sensing applications, like those based on the distance measuring and the sound wavelength. For many industrial applications, the sound speed in air is considered as constant, but this is true only for constant environment properties, like indoor environments with air-conditioning systems. Even then, the speed of sound can have different constant values for different sets of environment properties, generated by their spatial or temporal variations. For outdoor environments, the supposition of constant sound speed can generate important errors of distance estimation, In addition, for low temperature values, the real distance to an object is smaller than measured distance by ultrasonic sensing, and this can be a dangerous situation. Hence, simple and accurate models of sound speed in air are very important for ultrasonic industrial applications. In this paper, models of sound speed in air are studied, and new models are proposed, which are capable of dealing with uncertainties generated by unknown air characteristics. In addition, expert rules for model selection are generated, and comparative simulation results are presented.

Abstract: For multi-storey buildings,different calculation methods of cold air infiltration heat consumption have great impact on heating heat load of rooms in winter. With taking different methods,the calculation results will vary widely when architectual desigh institutes calculate room heat load. This paper compared the gap method,the ventilation rate method and the percentage method for the certain rooms infiltration heat loss,trying to make that simple and in line with the actual engineering calculation method.

Abstract: In order to verify the possibility that polymer materials for micro heat exchanger could replace metal materials, polymer micro heat exchangers are regarded as the study object. In terms of the experiments and the simulations by Flo EFD software, temperatures, pressures and speeds on micro heat exchanger made by aluminum and conductive plastic Polyphenylene Sulfide (PPS) were carried out analysis respectively. The results showed that the cooling capacities of micro-heat exchangers made by these two materials are quite the same. According to cooling capacity, manufacturing cost and weight, the micro heat exchanger made by conductive plastic is entirely possible to replace the existing metal heat exchanger.

Abstract: The excellent thermal hydraulic performances of coolers are the foundations of vehicular safety and stability. Structure, material, fin type and arrangement all have important effects on the thermal hydraulic performances. Numerical simulation method was adopted in this paper to investigate the effect of fin arrangement. The fluid flow and heat transfer performances were contrasted and analyzed under two different fin arrangements. It was found that fin arrangement effected thermal hydraulic performances severely and during the design process of a cooler, the performance requirements could be met through adjusting fin arrangements.

Abstract: The high temperature operation of Evacuated Tube Collectors (ETC) and their very low radiant heat losses make them ideal for solar water heating, solar space heating, desiccant air conditioning, thermal driven cooling and industrial process heating applications. The work temperature of common ETC can reach 100~ 250°C. The vacuum tube envelope minimizes heat loss and ensures high collector durability and steady performance. This paper investigates different types of solar thermal collectors and compared them so that the result which the heat loss of ETC is least is obtained. The thermal analysis and performance of ETC are investigated as well.