Key Engineering Materials Vols. 419-420

Abstract: A new kind of walking assistance mechanism in aided-walking wheelchair is proposed to help stroke and cord injury patients on gait rehabilitation training and aided-walking indoor and outdoor. Each side of the walking assistance mechanism, which is a double-crank linkage mechanism actuated by one driver, assists the motion of thigh and shank synchronously. The mechanism can control the walking gait of both legs to assist the patients in walking and gait rehabilitation training. The mechanism is analyzed, and the optimal proportion of the structure dimension suitable for different person is obtained according to the clinical gait analysis data. The simulation results show that the walking assistance mechanism can simulate the nature gait during human walking and realize the walking assistance and gait rehabilitation training function.

Abstract: Free-form surface interpolation functions give more advantages in machining than the traditional line and circle functions. A method is developed to convert lines and circles into Pythagorean-hodograph (PH) curves. In order to get smooth machining process the PH curve is used to replace the joints of the circular/linear elements by the connection situation. The slope of line is used to get the tangent vector in the line conversion. When converting a circle to a PH curve, points of the divided circle are introduced to compute the vectors. The methods of computing tangent vectors are proposed according to the slope of the line and the quadrant of the circle. The transformation errors from lines and circles to PH curves are computed. In the corner smoothing process the tangent vectors are computed by the connection between lines and circles. Replacement errors at the joints are computed for the use of PH curve. The results demonstrate the feasibility of the conversion from line and circle to PH curve. The PH curves at the joints of the circular and linear elements show continuous trajectory.

Abstract: Both fuzzy c-means (FCM) clustering and outlier detection are useful data mining techniques in real applications. In this paper, we show that the task of outlier detection could be achieved as by-product of fuzzy c-means clustering. The proposed strategy consists of two stages. The first stage consists of purely fuzzy c-means process, while the second stage identifies exceptional objects according to a novel metric based on the entropy of membership values. We provide experimental results to demonstrate the effectiveness of our technique.

Abstract: This paper has designed a multi-degree-of-freedom electro-hydraulic mix- drive motion simulator, which could move and turn spatially. It has both the advantages of the parallel turnplate and the series turnplate. The homogeneous coordinate transformation matrix was used to analyze the simulator’s state of motion. The position and attitude matrix for describing the simulator movement has been obtained. The kinematics equation for showing the relation of the positions between hydraulic drive rod and the turnplate was given, thus provided the theory basis for the further research to the simulator.

Abstract: The purpose of this paper is to investigate the optimal placement of piezoelectric actuator for active vibration control of smart structure. The structures can be described in the modal space based on the independent modal space control method and dynamic equations derived from finite element model. The modal damping ratios are derived from modal equations and an optimal target is given by maximizing the modal damping ratios. Accumulation method is adopted to the optimization calculation. Simulations are carried out for active vibration control of a conical shell with distributed piezoelectric actuators. Control effects proved the validity of the optimal method above by compared with the non-optimal results. The optimal method in this paper gives a useful guide for quantity optimization of actuators to piezoelectric structures.

Abstract: The purpose of this paper is to solve the positioning problem of a double body working ship. Dynamic characteristics of mooring system are analyzed with the effect of wind, wave and current. According to the dynamic equations of the system in the horizontal plane, longitudinal force coefficient, lateral force coefficient and yawing moment coefficient are obtained by towing test. The wind lord, wave load, current load and chain force can be calculated by empirical formulas. The motions of a mooring system are simulated in MATLAB. The results show that yawing motion would be occurred for the mooring system with single anchor at one point. The motions of the system have similar forms under the same amplitude of external loads. The results are agreed well with the observation data from documents about this relation. It is also can be point out that single point mooring system has poor stability and can not control the motion accurately. Thus dynamic positioning/mooring system should be developed for anchored working ships. This research in this paper provides the theoretical support and the analysis foundation for the further studies.

Abstract: Underwater interfacing device of flexible manipulators is designed in order to avoid blindness and fatalness of direct interfacing and fit the condition of low visibility and large leaning swing. At initial stage of interfacing, velocity expression of single manipulator is obtained. According to position relation of interfacing device and aim circle, coordinate transforming matrix is obtained through analysis. Considering limiting relation of harmony movement, the method of Denavit- Hartenberg is adopted to get velocity expressions of two opposite manipulator ends. At pulling down state, reverse kinematical solutions of parallel mechanism are solved to obtain lengths of manipulators.

Abstract: The authors built up a new algorithm called FUZZY-D-P-GA which was based on the fuzzy optimization, the genetic algorithm, delicate variables’ segments thinking & parallel principle. Meanwhile, they also succeed in applying this composite method on the synthetically optimization of navigation performance and structure characteristic of ships. Through a large number of calculation, the results showed that this kind of algorithm had high efficiency and it was also reliable.

Abstract: In order to make the liquid crystal display (LCD) panel thinner, brighter and no-Hg containing, the light emitting diodes (LEDs) are generally beginning to replace conventional cold cathode florescent lamp (CCFL) as light sources for LCD backlight unit (BLU). The thermal management and cost are consideration caused by more LEDs used for larger size BLU. For saving the fabrication cost and considering the luminous uniformity of most commercial BLU, a novel C-like linear tube is fabricated by precision and micromachining technique. The LED C-like linear tube is not only decreasing LEDs for BLU but also increasing the optical efficiency for emitting the light into the BLU. The C-like linear tube is proposed to replace CCFL tube for thin film transistor (TFT) LCD applications.

Abstract: The scheduling problem of LED chip sorting workstation is a multiprocessor open shop scheduling problem. In practice, this problem is usually solved with finding a dispatching rule to achieve certain performance indexes. Experimental design was applied to find a proper rule, and dispatching rule, wafer quantity, wafer mix type, and bottleneck location were chosen as independent variables. Maximum make-span and average queuing time were selected as dependent variables. Five dispatching rules were considered in the dispatching rule factor. Experimental results showed that all independent variables are significant on all dependent variables. While make-span as the performance index, three dispatching rules common in applying LPT in bottleneck machines obtained better results. A dispatching rule with applying SPT in non-bottleneck machines has least average queuing time among those three, and this rule is recommended for practical application.