No abstract

Performance evaluation is indispensable for a surgical simulator to become acceptable. A haptics-based dental simulator (iDental) has been developed and preliminary user evaluation on its first-generation prototype has been carried out to gain the knowledge. Based on detailed requirement analysis of Periodontics procedures, a combined evaluation method including qualitative and quantitative analysis was designed. Construct validity was used to compare the performance difference between two groups of participants (faculty members and dental graduate students). These participants were required to perform three periodontal examination and treatment procedures including periodontal pocket probing, calculus detection, and removal. From the evaluation results, we found that penetration between tool and teeth or cheek will greatly decrease the fidelity of the simulation, therefore, it is necessary to utilize 6-DOF haptic device with both force and torque feedback in dental simulator, and accordingly it is needed to extend point-based rendering to 6-DOF haptic rendering of multiregion contacts. Furthermore, several other key research topics that will enable haptic technology to be effective in a practical dental simulator were identified, including simulation of deformable body such as tongue and gingival, and simulation of occlusion of tongue and cheek on teeth, etc.

We developed a new method, SUT (Scheme Update on tissue Transparency), to view cardiac microstructures and unveil the molecular changes underlying cardiac diseases. SUT is an effective method to clear whole-hearts from different species. Over the course of 4 - 6 days we obtained transparent whole-layer left ventricular tissues from mice with only an approximate 1% protein loss. In addition, EAL (Electrophoretic Antibody Labeling) was used to achieve fast antibody labeling by electric force, which significantly reduced antibody incubation time from days to hours. SUT, together with EAL and modern imaging techniques, were successfully used to visualize three-dimensional spatial distribution of various molecules in cardiac tissue. We also observed changes in the number and phenotypes of fibroblasts during post-myocardial infarction in a stereoscopic pattern. We believe that our technique opens a new avenue to explore the mechanisms underlying cardiac diseases.

No abstract

A simultaneous phase-shifting dual-wavelength interferometry based on two-step demodulation algorithm is proposed in this Letter. First, two lasers with different wavelengths go through the same inline phase-shifting interference system simultaneously, and a sequence of five frames of simultaneous phase-shifting dual-wavelength interferograms (SPSDWIs) with the special phase shifts are captured by a monochrome CCD. Subsequently, using the subtraction between the first SPSDWI and the other SPSDWI, each wavelength of two frames of single-wavelength interference images (SWIIs) without the background can be achieved. Finally, using two-step demodulation algorithm, the wrapped phase of each single-wavelength can be determined easily and quickly with high accuracy.

Directional dithering of a laser beam potentially limits the detection accuracy of a laser triangulation displacement probe. A theoretical analysis indicates that the measurement accuracy will linearly decrease as the laser dithering angle increases. To suppress laser dithering, a scheme for reduction of the influence of laser beam directional dithering in a laser triangulation displacement probe, which consists of a collimated red laser, a laser beam pointing control setup, a receiver lens, and a charge-coupled device, is proposed in this paper. The laser beam pointing control setup is inserted into the source laser beam and the measured object and can separate the source laser beam into two symmetrical laser beams. Hence, at the angle at which the source laser beam dithers, the positional averages of the two laser spots are equal and opposite. Moreover, a virtual linear function method is used to maintain a stable average of the positions of the two spots on the imaging side. Experimental results indicate that with laser beam pointing control, the estimated standard deviation of the fitting error decreases from 0.3531 mm to 0.0100 mm, the repeatability accuracy can be lowered from ±7 mm to ±5 sans-serifμnormalm, and the nonlinear error can be reduced from ±6 % FS (full scale) to ±0.16 % FS.

No abstract

In this paper an inverse concept idea is presented to determine the main configuration dimensional parameters of a novel 5-DOF parallel kinematic machine tool. By the new described orientation workspace, the motion of the passive joints on the moving platform can be expressed in the fixed coordinate analytically. Some relationships between the reachable workspace and the dimensional parameters of the parallel machine tool have been obtained with graphical representation.