Abstract: In order to improve the real-time and stability of Permanent Magnet Synchronous Motor(PMSM) controller system, and to realize the integrated control of PMSM driving system and regenerative braking system, in this paper, the PMSM controller using FPGA as the central processor is designed, which is based on the PMSM vector control principle. Firstly, PMSM driving and regenerative braking model are analyzed; and then the design method and timing waveforms for PMSM control based on FPGA are described. Results of PMSM driving experiment and PMSM regenerative braking experiment have shown that the performance of PMSM controller system based on FPGA is much better
Abstract: In order to obtain better understanding of the resistance spot weldability of magnesium alloy and provide some foundational information for improving mechanical properties of the magnesium alloy joint, the influencing factors of pore formation during resistance spot welding of magnesium alloy, such as preexisting pores in base material, hydrogen rejection, shrinkage strain and expulsion, were analyzed; the corresponding restraining measures were discussed. The analyses reveal that the shrinkage strain and expulsion are important factors in contributing to the formation of pores during resistance spot welding of magnesium alloy, and that the pore formation could be suppressed by adjusting welding parameters.
Abstract: Dimensional control is one of the most important challenges in shipbuilding industry. In order to predict assembly dimensional variation in block construction of shipbuilding, a variation stream model based on state space is presented in this paper, which can be further applied to accuracy control. Both locating error and welding deformation are taken into consideration in this model, and variation propagation mechanisms and accumulative rule in the assembly process are analyzed, then, a model is developed to describe the variation propagation throughout the assembly process, finally, an example of flat block construction is given to provide this method is effective and useful.
Abstract: According to the increasing demand for the steel pipe in the world nowadays, as an effective method, ultrasonic testing plays a very important role in quality controlling procedures. Compared to the mature technology of the world, the domestic one still has some technical difficulties in high-speed probe rotating mode. This paper proposes an approach of combination of multi-probe arrays based on the internal detection way to solve the difficulty of coarse pitch. The structure of the inspection system is described with the workflow laying out. The practicability and reliability of the system is verified by means of a mass of experiments. The numeric automatic ultrasonic testing system has been successfully used and the technical data is given out at last.
Abstract: The traditional control system of rapid protyping machine for ceramic parts has many shortcomings: complex wiring, low control accuracy, incovenience maintenance and lack of flexibility, while the control method based on PLC can improve the comprehensive performance of the overall machine. The paper selectsSIEMENS S7-200 small PLC system to do generalized design for the rapid protyping machine for ceramic: including the wiring conection of hardware and distribution of I/O; programming by V4.0 STEP7-Micro/WIN SP3 software,which is flexible, interface friendly and debugging convienent.
Abstract: The working principle of the fully hydraulic static balancing machine with high accuracy is introduced, which is used to check marine propeller balance degree. First of all, the measuring precision of the apparatus is discussed, which is usually effected mainly by the mechanical centering error of the propeller measured. Then, the methods to eliminate the error are brought forward. The conclusion from the previous analysis and research has significance for improving of the static balance measuring degree of marine propeller.
Abstract: The kink effect is a harassed issue existing in metal-oxide-semiconductor field-effect transistors (MOSFETs) and usually degrades the whole chip performance, especially in analog circuit operation. No matter what the device isolation is with local oxidation of silicon (LOCOS) process or shallow trench isolation (STI) process, this effect more or less depicts. How to sense this effect in integrated-circuit (IC) mass-production is a crucial event. Through a second derivative method on Ids versus Vgs curves in MOSFET device, the unhealthy devices can be effectively screened out with the application of programmable auto testers. Using this derivative metrology implemented into the measurement testers, the distribution of kink devices on wafer is easily plotted. This information is very precious to the semiconductor process engineers in process improvement, too.
Abstract: Our recent high resolution core level and valence level X-ray photoelectron spectra (XPS) of Natural-Styrene Butylene Rubber (NR/SBR) demonstrated much narrower linewidths than previously obtained on rubbers or other polymer coatings. This improvement is due to low-current, low-energy beam flood gun charge compensation on non-conductor rubbers. The different charging has compensated on the rough surface and in the bulk of sponge structure in depth 50 Å of rubber sample. Despite residual charging has occurred on the surface which is apparent in C1s and O1s shoulder on its right side of the peak shape. Carbon groups such as C-H, C-C, C=C cannot be easily differentiated by their principal C(1s) peak chemical shift. Carbon black fillers seem to behave quite differently in the rubber-curing reaction. The stability of vulcanized rubber with sulfur curing system was studied in components of C(1s), O(1s), S(2p) regions which represented appropriate estimation of changes of crosslinked with sulfide bonds on rubber surface. The connection between the Shore hardness of rubber and the presence of carbonyl and sulphonyl groups was apparent. A model has been proposed for the degradation of the crosslinking density of rubber after long term exposure.
Abstract: A suitable starch hydrolysis strategy is crucial for conversion of starch into fermentable sugar, both with regard to reducing hydrolysis cost and increasing hydrolysis efficiency. A mathematical model for starch hydrolysis has been developed to predict sugar released curves based on experimental data from starch cold enzyme hydrolysis. At the first part of cold enzyme hydrolysis, starch was hydrolyzed by α-amylase (EC 126.96.36.199) and conversion into dextrin and glucose. Secondly, the residual starch and dextrin were second hydrolysis by glucoamylase (EC 188.8.131.52) into glucose. Fitting of experimental data was made by non-linear regression. Parameters values calculate were obtain from previous studies or experiments. Though mathematic formulation, the kinetic model was able to fit experiment with very good agreement. This model can be used for simulation of the industrial process and for faults detection. It can also be utilized for the optimization and even for the supervised control of the process.
Abstract: The standard for digital print quality and its measurement technology is now under consideration, and uniformity evaluation should be an important and essential quality factor. The paper provides a practical quantitative measurement method for traditional visual assessment on uniformity, and proposes a simple and effective IUI index to evaluate the uniformity of digital prints through NPS curve of the printed flat areas and CSF of HVS. The validity of the IUI is demonstrated through its applications in the uniformity assessment of the digital prints.