Cranioplasty is the procedure that repairs holes or defects in the skull with cranial implants. When the bone from the hole is missing, damaged, or infected, the defect needs to be covered with an artificial plate to protect the brain. In this study, a hole-repairing algorithm is developed to aid shaping artificial plates for cranioplasty by describing a method for filling holes in defective biomodels with unstructured triangular surface meshes or in stereolithography format. The resulting patching meshes interpolate the shape and density of the surrounding mesh. The steps in repairing a hole include hole identification, hole triangulations using genetic algorithm (GA) optimization, and a customized advancing-front meshing technique using surface approximations based on a Quartic Bézier Gregory patch.

Construction noise is one of the main sources of noise pollution in many cities, and degrades the comfort level of living spaces. It was previously reported that a noise barrier with a wide “cross-sectional profile” (e.g., T- or Y-shaped) could enhance the noise attenuation performance, and the jagged edge “longitudinal profile” on the top edge of the noise barrier could generate destructive interference sound fields behind the noise barrier, which could further reduce the noise levels. The present paper attempts to study the noise attenuation performances of jagged edge profiles applied on the edge of a cantilever, which was mounted at the top of a commercial passive noise barrier. In addition to the numerical simulations, the full-sized prototypes were also experimentally tested on a construction site with noise generated by a boring machine. Both numerical simulation and experimental results showed that this barrier with slanted flat-tip jagged cantilever would perform better than the traditional barrier having a Straight edge cantilever of same height, with a maximum additional attenuation of 5.0 dBA obtained experimentally. The barrier with a slanted flat-tip jagged cantilever could also extend the shadow zone behind the barrier to higher levels.

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This paper presents a novel piezoelectric ultrasonic motor which is able to exert the strong actuating power of piezoelectric stacks. It is a linear standing wave motor with simple structure and high positioning speed. Elliptical motion at the driving point is achieved by simultaneously matching the natural frequencies of two operating modes of the device. The matched resonance is taken to be the operating frequency at which both modes can be excited. A prototype motor is developed and numerically analyzed. Vibration characteristics of the motor, such as mode shapes, natural frequencies, output displacement in frequency and time domains, electrical impedance of the stacks and trajectories of the driving point, are obtained from finite element analysis. The results confirm that the motor has high electromechanical efficiency with good mechanical output characteristics.