Study on a ultra-light dual revolute manipulator with high joint torque

This paper details a study performed on a new proposed twelve degree-of-freedom dual robot arm, which is very light but capable of handling heavy loads. The proposed robot arm has a higher value for the ratio of the load capacity/robot weight than conventional robot arms, which are actuated by motors with speed reducers, such as a harmonic drives, since it adopts a new type of robot actuator based on a closed chain mechanism. Because of the high value of the ratio of the payload capacity/robot weight, it can be used as a robot arm for mobile robots and for walking robots. Analyses of the design scheme and of the mechanism of the joint actuator used for the robot arm are presented. Also, the control system developed for the robot arm is introduced. The superior characteristics of the new proposed robot arm, handling heavy payloads with light weight links compared to industrial robots, are presented through carrying out various payload capacity tests. Since the robot arm is designed with light links, it has some deflections and these deflections of the links are analyzed using the Finite Element Method (FEM). The results of performance tests are presented to check the correctness of the FEM analysis and to demonstrate the actual capability of handling heavy payloads applied to the robot arm.     

Research on characteristics and effects of combustion performance by amplified ignition energy in CVCC system

Journal of Mechanical Science and Technology - This study was conducted to analyze the flame characteristics, which is generated through the combustion process according to air/propane mixture...     

MRT letter: Recovering weak‐textured surfaces using image focus

In nature, objects have partially weak texture and their shape reconstruction using focus based passive methods like shape from focus (SFF), is difficult. This article presents a new SFF algorithm which can compute precise depth of dense as well as weak textured objects. Segmentation is applied to discard wrong depth estimate and then later interpolating them from accurate depth values of their neighbors. The performance of the proposed method is tested, using different image sequences of synthetic and real objects, with varying textures. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.     

Accurate shape from focus based on focus adjustment in optical microscopy

Optical microscopy allows a magnified view of the sample while decreasing the depth of focus. Although the acquired images from limited depth of field have both blurred and focused regions, they can provide depth information. The technique to estimate the depth and 3D shape of an object from the images of the same sample obtained at different focus settings is called shape from focus (SFF). In SFF, the measure of focus–sharpness–is the crucial part for final 3D shape estimation. The conventional methods compute sharpness by applying focus measure operator on each 2D image frame of the image sequence. However, such methods do not reflect the accurate focus levels in an image because the focus levels for curved objects require information from neighboring pixels in the adjacent frames too. To address this issue, we propose a new method based on focus adjustment which takes the values of the neighboring pixels from the adjacent image frames that have approximately the same initial depth as of the center pixel and then it re-adjusts the center value accordingly. Experiments were conducted on synthetic and microscopic objects, and the results show that the proposed technique generates better shape and takes less computation time in comparison with previous SFF methods based on focused image surface (FIS) and dynamic programming. Microsc. Res. Tech., 2009. © 2008 Wiley-Liss, Inc.     

Active wafer shape modulation using a multi-actuator chucking system

Jet and Flash Imprint Lithography has proven to be a viable alternative to optical lithography for fabrication of sub 30 nm nanostructures for large volume semiconductor manufacturing. Machine throughput, overlay and process defectivity that meet and exceed the International Technology Roadmap for Semiconductors (ITRS) are essential for commercial viability of any new lithography technology. Jet and Flash Imprint Lithography uses an inkjet head to dispense a grid of liquid drops on the wafer surface to match the volume requirements of the pattern being imprinted. Wafer shape modulation has been shown to increase imprinting speed significantly by reducing air bubble trapping in the drop interstitial sites. A wafer shape modulation chuck that can address arbitrary field locations and sizes on a wafer with a novel actuation scheme that minimizes the number of actuators while increasing imprinting speed and reducing process defects significantly is presented.     

RETRACTED ARTICLE: Development and application of intensified envelope analysis for the condition monitoring system using acoustic emission signal

The application of the high-frequency acoustic-emission (AE) technique in the condition monitoring of rotating machinery has been increasing of late. It has a major drawback, though, the attenuation of the signal, and as such, the AE sensor has to be close to its source. Two signal-processing methods, envelope analysis and wavelet transform, were found to be useful for detecting faults in the rolling element bearing and gearboxes. These methods have a disadvantage, though: their application is focused only on a component of the assembled machine. For example, envelope analysis is a powerful method for detecting faults in the bearing system, but it is not proper for use in the gear system. Thus, these methods could not be used to detect combined faults in the common assembled machines. Therefore, we propose a signal-processing method consisting of envelope analysis and DWT (discrete wavelet transform). In addition, a novel mother function optimized for the AE signal for DWT was extracted through a fatigue crack growth test, and is also proposed herein. Then the proposed method, called intensified envelope analysis (IEA), was used to detect the faults in the rolling element bearing and rotating shaft. According to the results, IEA can be a better signal processing method for the condition monitoring system using AE technique.     

Molecular and chemical investigations and comparisons of biomaterials for ocular surface regeneration

This study investigated and compared the ultrastructural and chemical properties of representative biomaterials for ocular surface regeneration: a human amniotic membrane (AM) in a basal plate, a human AM in reflected chorion, a preserved AM, and a human corneo‐scleral tissue. Assessments of the morphological differences in the extracellular matrices were evaluated by hematoxylin–eosin, Masson's trichrome (for total collagen), and picrosirius‐red (for newly synthesized collagen) staining. Assessments of the changes in the molecular structures and chemical compositions of the biomaterials for ocular surface regeneration were evaluated by Raman spectroscopy. A placental AM (52 %) was a dense and thick collagenous structure compared to a reflected AM (23 %). The spectroscopy did not obtain any structural information for a preserved AM. The cornea group (100 %, control) and sclera group (104 %) showed the collagen lamellae and interfibrillar spacing, and a slight inflammatory reaction with more fibrous and granulomatous tissues. There was a formation of newly synthesized collagen in a placental AM, while there were few collagen components in a reflected AM. Human AM tissues showed consistent Raman spectra and the characteristic collagen bands, similar to the corneal and scleral tissues. Therefore, these findings suggest that human placental AM and reflected AM are structurally suitable for scleral and corneal surface regeneration, respectively, while human placental or preserved AM and reflected AM are molecularly and chemically suitable for corneal and scleral surface regeneration, respectively. Microsc. Res. Tech. 77:183–188, 2014. © 2013 Wiley Periodicals, Inc.     

Direct numerical simulation of flow characteristics and heat transfer enhancement in a rib-dimpled cooling channel

The present study reports the numerical investigation on the flow characteristics and heat transfer enhancement of the rib-dimpled channels. Two geometric variables were considered: the rib angle, θ, and the length between the rib center and the dimple rim, l. Nine cases were investigated by combining three different rib angles with three different lengths. Direct numerical simulations were conducted with a Reynolds number of 2800. As θ and l changed, the flow characteristics of the rib-dimpled channel were altered, which lead to different characteristics in the flow mixing and heat transfer rate. The span-wise rotating flow and the up-wash counter rotating vortices played an important role in the augmentation of heat transfer rate. The rib-dimpled channel with l = 0.15 and θ = 70° showed the maximum increase of 32 % in the volume goodness factor, in comparison with the general dimpled channel.

     

A study on the thermal characteristics of hydrogen storage vessel related to condition of charging

Recently, study on renewable energy has been carried out due to environmental pollution and depletion of fossil fuels. In particular, hydrogen, a clean energy, is environmentally friendly because it produces only pure water as a by-product of the reaction process. In the case of liquified hydrogen, the energy density is about 848 times higher than that of gas hydrogen, but it is not currently widely used due to technical constraints and other problems because it has to maintain a cryogenic state. Therefore, in this work, numerical method was verified by comparing results of precedent study and this study. And relationship between Reynolds number and Nusselt number was confirmed. Based on this results, code was made by using programming language (Fortran 77) with relationship between Reynolds number and Nusselt number to analyze the state of charge (SOC). Variables were set as mass flow rate, temperature of hydrogen gas, and initial tank temperature. As a result, the effect of hydrogen gas temperature is dominant as a factor that affects the temperature of the fully charged state. Therefore, it is determined that the temperature control of the hydrogen storage will be possible through the hydrogen gas temperature setting.