Surface contour error model of five-axis machining considering multifactor coupling effects

During five-axis flank milling procedure, the static deflection of workpiece and cutter creates surface errors that lead to defects in projects with strict requirements, especially in thin-walled parts industry. Focusing on the mentioned issues, the surface contour error is predicted in this paper considering the coupling between the deflection and cutting force. First, an efficient calculation method of the cutting force is presented in five-axis flank milling. This method accounts for the impact of cutter runout on cutter/workpiece engagement (CWE) and the instantaneous undeformed chip thickness (IUCT). Then, a cutter is modelled as a cantilever structure and thus an analytical solution for the deflection of the end mill can be obtained. Next, the flexible cutting force is distributed on a finite element (FE) model of workpiece, while the workpiece stiffness keeps varying with the material removal. Subsequently, a flexible iterative calculation method for achieving deflection prediction is established. Finally, the prediction model is proven by machining tests of an S-shaped specimen in which predicted values of the surface error match with the experimental results.

Heat Transfer Augmentation of Concentrated Solar Absorber Using Modified Surface Contour

This work aims to compare the cavity surface contour’s thermal performance to that of the solar absorber’s plain surface contour for Scheffler type parabolic dish collectors. The absorber is tested for the temperature range up to 600°C without working fluid and 180°C with the working fluid. The modified absorber surface's thermal performance is compared with the flat surface absorber with and without heat transfer fluid. The peak temperature reached by the surface modified absorber (534°C) is about 8.6% more than that of the unmodified absorber (492°C) during an outdoor test without fluid. The energy efficiency of cavity surface absorber and plain surface absorber are 67.65% and 61.84%, respectively. The contoured cavity surface produces a more uniform temperature distribution and a higher heat absorption rate than the plain surface. The results are beneficial to the design of high-temperature solar absorbers for concentrated solar collectors.

Heat Transfer Augmentation of Concentrated Solar Absorber Using Modified Surface Contour

This work aims to compare the cavity surface contour’s thermal performance to that of the solar absorber’s plain surface contour for Scheffler type parabolic dish collectors. The absorber is tested for the temperature range up to 600°C without working fluid and 180°C with the working fluid. The modified absorber surface's thermal performance is compared with the flat surface absorber with and without heat transfer fluid. The peak temperature reached by the surface modified absorber (534°C) is about 8.6% more than that of the unmodified absorber (492°C) during an outdoor test without fluid. The energy efficiency of cavity surface absorber and plain surface absorber are 67.65% and 61.84%, respectively. The contoured cavity surface produces a more uniform temperature distribution and a higher heat absorption rate than the plain surface. The results are beneficial to the design of high-temperature solar absorbers for concentrated solar collectors.

Cardboard Bed Without Mattress Is Ineffective in Improving the body Contact Pressure-a Preliminary Study Using a Dummy Model

Objective This study aimed to describe and evaluate the dispersion of body-mattress contact pressure on a cardboard bed and investigate whether the cardboard bed has a positive effect on evacuees’ musculoskeletal burden. Materials and Methods A high-performance nursing simulator was used to measure the contact pressure and the body surface contour area of the bed, and these values were collected with the patient in the supine position using the Body Pressure Measurement System. Data of each test were acquired 10 times and were compared among 4 conditions (plastic sheet, cardboard bed, cardboard bed with a blanket, and cardboard bed with a mattress-topper). The data analysis for body-mattress contacts pressure and the surface contour area of the whole body, head, chest, and buttocks were conducted by one-way repeated analysis of variance and Bonferroni post-hoc test. Results The average body-contact pressure on the cardboard bed did not decrease compared with that on the floor with plastic sheets. In contrast, the body surface contour area was significantly different among any other conditions, but the gap was only approximately 16%. However, the body-contact pressure and the body surface contour area were improved when a mattress-topper was added on the cardboard bed. When a blanket was laid on the cardboard bed, the contact area was increased. Conclusion Our results indicate that the pressure dispersion ability of the cardboard bed was not sufficient; however, adding the mattress-topper or the blanket could contribute to an improvement in the evacuees’ musculoskeletal burden. Many evacuees lay a mattress topper or futon on a cardboard bed after installing cardboard beds. Our findings may also support the scientific validity of the evacuees’ actual sleeping style in Japan. This preliminary study provides the basis for future research on exploring an appropriate sleeping bed condition in evacuee shelters.

Colposcopy Findings In High-Grade Cervical Precancer Lesion

Cervical precancer lesion can generally be seen in the transformation zone. Colposcopy allows us to see an image of enlarge precancer lesion in the transformation zone. The colpocopist should consider some important things to determine the appearance of low-grade lesion or high-grade lesion. Two important things are the description of abnormal epithelium and the description of abnormal blood vessels. The description of the abnormal epithelial seen after administration of acetic acid 3-5%, acetowhite looks faster and disappears slower. The “white” lesion is more concentrated like the color of shells, with clear border and surface contour. To find the abnormal blood vessels more clearly, we can use the green filter. High-grade lesion shows rough mosaic and rough punctation or both. In addition, finding the cervical blood vessels can help us to determine high-grade lesion. By understanding the description of the epithelial cervix and abnormal blood vessels , we will easily distinguish high-grade lesions from low grade lesion. Keywords: cervical precancer, colposcopy findings

Colposcopy Findings In High-Grade Cervical Precancer Lesion

Cervical precancer lesion can generally be seen in the transformation zone. Colposcopy allows us to see an image of enlarge precancer lesion in the transformation zone. The colpocopist should consider some important things to determine the appearance of low-grade lesion or high-grade lesion. Two important things are the description of abnormal epithelium and the description of abnormal blood vessels. The description of the abnormal epithelial seen after administration of acetic acid 3-5%, acetowhite looks faster and disappears slower. The “white” lesion is more concentrated like the color of shells, with clear border and surface contour. To find the abnormal blood vessels more clearly, we can use the green filter. High-grade lesion shows rough mosaic and rough punctation or both. In addition, finding the cervical blood vessels can help us to determine high-grade lesion. By understanding the description of the epithelial cervix and abnormal blood vessels , we will easily distinguish high-grade lesions from low grade lesion. Keywords: cervical precancer, colposcopy findings