Ji-Liang Doong

Use of Virtual Reality to Improve Upper-Extremity Control in Children With Cerebral Palsy: A Single-Subject Design

Background and Purpose: Virtual reality (VR) creates an exercise environment in which the intensity of practice and positive feedback can be systematically manipulated in various contexts. The purpose of this study was to investigate the training effects of a VR intervention on reaching behaviors in children with cerebral palsy (CP). Participants: Four children with spastic CP were recruited. Method: A single-subject design (A-B with follow-up) was used. All children were evaluated with 3 baseline, 4 intervention, and 2 follow-up measures. A 4-week individualized VR training program (2 hours per week) with 2 VR systems was applied to all children. The outcome measures included 4 kinematic parameters (movement time, path length, peak velocity, and number of movement units) for mail-delivery activities in 3 directions (neutral, outward, and inward) and the Fine Motor Domain of the Peabody Developmental Motor Scales–Second Edition (PDMS-2). Visual inspection and the 2-standard-deviation–band method were used to compare the outcome measures. Results: Three children who had normal cognition showed improvements in some aspects of reaching kinematics, and 2 children’s change scores on the PDMS-2 reached the minimal detectable change during the intervention. The improvements in kinematics were partially maintained during follow-up. Discussion and Conclusion: A 4-week individualized VR training program appeared to improve the quality of reaching in children with CP, especially in children with normal cognition and good cooperation. The training effects were retained in some children after the intervention.

Driver Fatigue and Highway Driving: A Simulator Study

Long duration of driving is a significant cause of fatigue-related accidents on motorways or major roadways. The fatigue caused by driving for extended periods acutely impairs driver alertness and performance and can compromise transportation safety. This study quantitatively measured the progression of driver fatigue and identified the conservative safe duration of continuous highway driving. Thirty young male subjects were analyzed during 90 min of laboratory-simulated highway driving. Sleepiness ratings (SSS) and reaction time (RT) tests were used to assess impairment of driver alertness and vigilance. Additionally, various measures of driving performance recorded throughout the experiment were used to measure temporal deterioration of driver performance from alert to fatigued using principal component analysis (PCA). The analytical results revealed that SSS scores, reaction times (RTs) and unstable driving performance significantly increased over time, indicating that excessive driving time is a significant fatigue factor and potential cause of fatigue-related accidents. Moreover, the analytical results indicated that 80 min was the safe limit for monotonous highway driving. Based on the experimental findings of this study, public awareness of the adverse affects of driver fatigue during long-distance driving should be enhanced. This study provides explicit information of fatigue development that can be used to prevent fatigue-related accidents.

Optimization of the injection molding process of short glass fiber reinforced polycarbonate composites using grey relational analysis

Abstract This paper presents a fast and effective methodology for the optimization of the injection molding process parameters of short glass fiber reinforced polycarbonate composites. Various injection molding parameters, such as filling time, melt temperature, mold temperature and ram speed were considered. The methodology combines the use of the GRA (grey relational analysis) method and a CAE flow simulation software, to simulate the injection molding process and to predict the fiber orientation. This method can replace the traditional “change-one-parameter-at-a-time” approach, which is very inefficient, costly, time consuming and almost impracticable to yield an optimum solution. At the same time, the fiber orientation was examined by CAE simulation to forecast the shear layer thickness, and simultaneously to check the accuracy of the GRA. The results indicated that three distinct layers (a frozen layer, a shear layer and a core layer) are observed from the surface to the core for various injection molding conditions. The fiber orientation is perpendicular to the melt flow direction in the frozen layer and the core layer, but it has the opposite direction in the shear layer. From the CAE analysis, the optimum process parameters to obtain the thickest shear layer are found, which is the target of the present research.

Vibration and stability of an initially stressed thick plate according to a high-order deformation theory

In this paper, the average stress method is used to derive the governing equation for a thick rectangular plate according to a high-order deformation theory. The applied load is taken to be a combination of a pure bending stress plus an extensional stress in the plane of the plate. The buckling loads and natural frequencies of simply supported plates are also investigated. Present results based on high-order theory are compared with the results of Brunelles theory and Reddys theory. In addition, the effects of various parameters on the natural frequencies are studied. More accurate results can be obtained by using the present theory than those of the other theories.

Large amplitude vibration of an initially stressed cross ply laminated plates

Abstract In this paper, nonlinear equations of large amplitude vibration for a laminated plate in a general state of nonuniform initial stress are derived. The equations include the effects of transverse shear and rotary inertia. Using these derived governing equations, the large amplitude vibration behaviour of an initially stressed cross-ply laminated plate is studied. The initial stress is taken to be a combination of pure bending stress plus an extensional stress in the plane of the plate. The Galerkin method is used to reduce the governing nonlinear partial differential equations to ordinary nonlinear differential equations and the Runge–Kutta method is used to obtain the nonlinear to linear frequencies. The frequency responses of nonlinear vibration are sensitive of the vibration amplitude, aspect ratio, thickness ratio, modulus ratio, stack sequence, layer number and state of initial stresses. The effects of various parameters on the large amplitude free vibrations are presented.

Nonlinear vibration of an initially stressed plate based on a modified plate theory

Abstract Nonlinear partial differential equations for the vibrating motion of a plate based on a modified higher order plate theory with seven kinematic variables are derived. The present seven-variable modified higher order plate theory satisfies the stress-free boundary conditions. Using these derived governing equations, the large amplitude vibrations of a simply supported thick plate subjected to initial stresses are studied. The Galerkin method is used to transform the governing nonlinear partial differential equations to ordinary nonlinear differential equations and the Runge–Kutta method is used to obtain the ratio of linear to nonlinear frequencies. Frequency ratios obtained by the present theory are compared with the Mindlin plate theory results and Los 11-variable higher order plate theory results. It can be concluded that present modified plate theory predicts frequency ratios very accurately. Also, the benefit of significant simplification can be observed as compared with the Los higher order plate theory. The effects of initial stress and other factors on frequency ratio are investigated.

High strain rate tensile properties of an (Al2O3 particles)-(Al alloy 6061-T6) metal matrix composite

Abstract The metal matrix composite materials consist of 10, 15 and 20 vol.% alumina particles in an aluminium alloy 6061-T6 matrix. Specimens were taken from hot-extruded rods and the tensile tests were carried out at various strain rates. High strain rate tests were performed by the split-Hopkinson-bar method. The fracture surfaces were observed with a scanning electron microscope to understand the fracture mechanisms. From the results, it can be concluded that: (1) the alumina-reinforced composites are more sensitive to strain rate than the unreinforced material, (2) the strain rate sensitivity of the ultimate tensile strength of these composites increases with increasing temperature and (3) the addition of alumina particles will reduced the ductility of aluminium alloy 6061-T6, irrespective of the strain rate and temperature.

Evaluation of computer-assisted multimedia instruction in intravenous injection

The purpose of this study was to develop a computer-assisted multimedia training course for intravenous injection and evaluate its effect on the knowledge and self-perceived performance of intravenous injection for novice nurses. Eighty-one novice nurses randomly assigned to the experimental group and control group participated a designed training procedure and took pretest and posttests. The test results were analyzed using statistical methods. From the study it could be concluded that the training course had a significant effect on the intravenous injections knowledge. Besides, a high rate of satisfaction for the multimedia program showed the self-developed program was successful.

Large-Amplitude Vibration of an Initially Stressed Thick Circular Plate

In this paper, nonlinear equations of motion are derived for a transversely isotropic thick circular plate in a general state of nonuniform initial stress. The equations include the effects of transverse shear and rotary inertia. The large-amplitude flexural vibrations of simply supported and clamped thick circular plates subjected to initial stress are also investigated. The initial stress is taken to be a combination of pure bending stress plus an extensional stress in the plane of the plate. Nonlinear equations of motion are used to solve the vibration problems by the Galerkin method. In addition, the effects of various parameters on the nonlinear vibration frequencies are studied.

Driving performance assessment: effects of traffic accident location and alarm content.

According to accident statistics for Taiwan, the two most common traffic accident locations in urban areas are roadway segments and intersections. On roadway segments, most collisions are due to drivers not noticing the status of leading vehicle. At intersections, most collisions are due to the other driver failing to obey traffic signs. Using a driving simulator equipped with a collision warning system, this study investigated driving performance at different accident locations and between different alarm contents, and identified the relationship between crash occurrences and driving performance. Thirty participants, aged 20-29 years, were recruited in this study. Driving performance measures were perception-reaction time, movement-reaction time, speed and a crash. Experimental results indicated that due to different demands for processing information under different traffic conditions, driving performance differed at the two traffic accident locations. On a roadway segment, perception-reaction time for a beep was shorter than the time for a speech message. Nevertheless, at an intersection, a speech message was a great help to drivers and, thus, perception-reaction time was effectively reduced. In addition, logistic regression analysis indicates that perception-movement time had the greatest influence on crash occurrence.