A FUNDAMENTAL STUDY ON MEASUREMENT OF HULL ROUGHNESS

In this study, an investigation on the hull roughness measurement of a new ship, a 160m class car ferry, was performed. The hull roughness measurement was conducted in the ferry’s pre-coated state before launching. For measurement, the TQC manual and ITTC recommendations were considered, and measurements were made in a total of 230 zones below waterline of the ship. Accordingly, the average hull roughness of the car ferry was 81μm, which is relatively low compared to 150μm, the hull roughness of a new ship proposed by the ITTC. In addition, the measurement uncertainty was calculated using the ISO guidelines, and the effect of the number of zones on the hull roughness measurement was examined. Using the measured average hull roughness, we estimated the resistance performance at the design speed of the ship. Accordingly, it was confirmed that the total resistance of the new ship was reduced by approximately 2% owing to a decrease in its frictional resistance increase

Bio-Inspired Optic Flow Sensors for Artificial Compound Eyes.

Compound eyes in flying insects have been studied to reveal the mysterious cues of vision-based flying mechanisms inside the smallest flying creatures in nature. Especially, researchers in the robotic area have made efforts to transfer the findings into their less than palm-sized unmanned air vehicles, micro-air-vehicles (MAVs). The miniaturized artificial compound eye is one of the key components in this system to provide visual information for navigation. Multi-directional sensing and motion estimation capabilities can give wide field-of-view (FoV) optic flows up to 360 solid angle. By deciphering the wide FoV optic flows, relevant information on the self-status of flight is parsed and utilized for flight command generation. In this work, we realize the wide-field optic flow sensing in a pseudo-hemispherical configuration realized by mounting a number of 2D array optic flow sensors on a flexible PCB module. The flexible PCBs can be bent to form a compound eye shape by origami packaging. From this scheme, the multiple 2D optic flow sensors can provide a modular, expandable configuration to meet low power constraints. The 2D optic flow sensors satisfy the low power constraint by employing a novel bio-inspired algorithm. We have modified the conventional elementary motion detector (EMD), which is known to be a basic operational unit in the insect’s visual pathways. We have implemented a bio-inspired time-stamp-based algorithm in mixed-mode circuits for robust operation. By optimal partitioning of analog to digital signal domains, we can realize the algorithm mostly in digital domain in a column-parallel circuits. Only the feature extraction algorithm is incorporated inside a pixel in analog circuits. In addition, the sensors integrate digital peripheral circuits to provide modular expandability. The on-chip data compressor can reduce the data rate by a factor of 8, so that it can connect a total of 25 optic flow sensors in a 4-wired Serial Peripheral Interface (SPI) bus. The packaged compound eye can transmit full-resolution optic flow data through the single 3MB/sec SPI bus. The fabricated 2D optic flow prototype sensor has achieved the power consumption of 243.3pJ/pixel and the maximum detectable optic flow of 1.96rad/sec at 120fps and 60 FoV.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/108841/1/sssjpark_1.pd

BIOMECHANICAL ANALYSIS A SEQENCE OF ANGULAR VELOCITY AND COORDINATED MUSCLES ACTIVITY DURING BASEBALL HITTING

The purpose of this study was to analyse a sequence of rotations and coordinated muscles activities of upper body. Using kinematic and EMG data from 3 recreational university baseball players participating in this study, we computed the angular velocity of trunk, pelvis, bat and trunk-pelvis rotation angle and PMT of upper body muscles. Trunkpelvis rotation angle was 22 ° before the bat-ball contact. The pelvis, trunk, and bat showed a sequence of angular velocity beginning with the hip, followed by the trunk, and end tip of the bat. Additionally, PMT of upper body muscles generated right pectoralis major(1.03 sec.), right external oblique(1.11 sec.), left thoracloumbar fasci(1.12 sec.), left external oblique(1.13 sec.), right latissimus dorsi(1.15 sec.), left latissimus dorsi(1.16 sec.), right thoracloumbar fascia(1.16 sec.), left pectoralis major(1.25 sec.), on at a time during baseball hitting motion. PMT of upper body muscles were related to the shifting and rotating of body segment and this action can be considered the coordinated muscle activities of upper body

3D Teeth Reconstruction from Panoramic Radiographs using Neural Implicit Functions

Panoramic radiography is a widely used imaging modality in dental practice and research. However, it only provides flattened 2D images, which limits the detailed assessment of dental structures. In this paper, we propose Occudent, a framework for 3D teeth reconstruction from panoramic radiographs using neural implicit functions, which, to the best of our knowledge, is the first work to do so. For a given point in 3D space, the implicit function estimates whether the point is occupied by a tooth, and thus implicitly determines the boundaries of 3D tooth shapes. Firstly, Occudent applies multi-label segmentation to the input panoramic radiograph. Next, tooth shape embeddings as well as tooth class embeddings are generated from the segmentation outputs, which are fed to the reconstruction network. A novel module called Conditional eXcitation (CX) is proposed in order to effectively incorporate the combined shape and class embeddings into the implicit function. The performance of Occudent is evaluated using both quantitative and qualitative measures. Importantly, Occudent is trained and validated with actual panoramic radiographs as input, distinct from recent works which used synthesized images. Experiments demonstrate the superiority of Occudent over state-of-the-art methods.Comment: 12 pages, 2 figures, accepted to International Conference on Medical Image Computing and Computer-Assisted Intervention MICCAI 202

Real-time observations of TRIP-induced ultrahigh strain hardening in a dual-phase CrMnFeCoNi high-entropy alloy.

Strategies involving metastable phases have been the basis of the design of numerous alloys, yet research on metastable high-entropy alloys is still in its infancy. In dual-phase high-entropy alloys, the combination of local chemical environments and loading-induced crystal structure changes suggests a relationship between deformation mechanisms and chemical atomic distribution, which we examine in here in a Cantor-like Cr20Mn6Fe34Co34Ni6 alloy, comprising both face-centered cubic (fcc) and hexagonal closed packed (hcp) phases. We observe that partial dislocation activities result in stable three-dimensional stacking-fault networks. Additionally, the fraction of the stronger hcp phase progressively increases during plastic deformation by forming at the stacking-fault network boundaries in the fcc phase, serving as the major source of strain hardening. In this context, variations in local chemical composition promote a high density of Lomer-Cottrell locks, which facilitate the construction of the stacking-fault networks to provide nucleation sites for the hcp phase transformation

COMPARISON OF PROPRIOCEPTION PERCEPTION TEST BETWEEN GOLFER AND NON-GOLFER USING TILTING PLATFORM

The purpose of this study was to test proprioception perception and compare between collegiate golfers and non-golfers using tilting platform. Sixteen male and fourteen female golfers and fifteen male and thirteen non-golfers were participated. All participants were performed perception test on the tilting platform. Frequency analysis and independent t-test were performed using SPSS 24.0. Alpha set at .05. Most participants were perceived from 1° to 2° of slopes and perceived left-right (target direction) slope than forward-backward slope. Repeated practice such as walking on the uneven ground or standing on sloped ground might help to improve proprioception perception. Further research using a tilting platform will be to develop the training program