V-shaped Micro Research Articles

Characteristics of collapsible red soil in Northeast Thailand

ABSTRACT We analyzed the characteristics of red soils that are often considered collapsible soils. In this study, we examined the depositional environment and lithologic characteristics, analyzed stratigraphy, and conducted mechanical sieve, X-ray fluorescence, X-Ray diffraction, scanning electron microscope, X-ray fluorescence analyses and optically stimulated luminescence dating. The samples were collected from the gravel pits to examine and reveal details of their depositional processes. The abrupt particle size change in the overlying soil formed a pseudo-disconformity with the subjacent gravel bed. The soil was unstratified with granule gravels scattered throughout the soil layer. The soil consisted of mostly sand (~70%), with minor silt and clay contents (~30%); thus, the soil was classified as silty sand. The soil samples contained a large amount of silicon, a high percentage of quartz. V-shaped micro textures represented percussion and abrasion mechanisms on the surface of individual grains, suggesting transport by fluvial processes. The deposition occurred during the Late Pleistocene, and the absence of desert environment suggested different conditions than those associated with aeolian deposition. Consequently, the lithology, physical and chemical properties, and chronology were consistent with termite mounding, which plays an important role in the upward transportation of small particles and causes large sediments to descend.

Influence of Shape Factor of a Beam Cross-Section on a Heat Transfer Process of the Electrothermal V-Shaped Micro Actuators

This paper proposes a method to determine the shape factor in the heat transfer model of silicon electrothermal V-shaped micro actuators by using ANSYS WORKBENCH. The rectangular cross-section model (w-width and h-thickness) is built to investigate the heat transfer from the beam to the substrate through a thin layer of air. Moreover, this model can be used to determine the influence of beam width and beam thickness or height on its shape factor. Through simulation, the lowest heat emission generated on the beam when the height-to-width ratio (h/w) is about from 3 to 4. The shape factor is proportional to the ratio of beam height to beam width as well as the air gap between the V-beam and the substrate. The objective of the paper is to provide an effective method to determine the shape factor in the theoretical heat transfer model of the electrothermal V-shaped micro actuators and can be also applied to similar heat transfer models of other actuators.

Convective boiling heat transfer of methanol – Hydrogen peroxide solutions in a microchannel evaporator

To provide uniform mixture of methanol vapor, steam and oxygen in a methanol reformer, the present study investigates the boiling heat transfer performance and two-phase flow of methanol and 50 wt% hydrogen peroxide mixture in an microchannel evaporator with V-shaped micro diffusers for the entrance region and 52 parallel diverging channels. The decomposition of hydrogen peroxide may produce oxygen and significant amount of heat making the convective boiling of the mixture extraordinary. Experiments of three volume ratios (C) of hydrogen peroxide to methanol of 1/2, 1/3, 1/4 and three flow rates, 0.18, 0.36, and 0.54 ml/min are conducted and analyzed. The experimental results reveal that the addition of hydrogen peroxide can significantly enhance boiling heat transfer as well as the critical heat flux possibly due to the Marangoni convection caused by concentration gradient, but the enhancement is limited by the introduction of decomposition heat internally in the working fluid. The oxygen and enhanced evaporation due to decomposition may make the boiling two-phase flow unstable and deteriorate the heat transfer. Consequently, the mixture with C = 1/3 showing the best heat transfer coefficient may be the optimized working fluid for a microchannel evaporator to serve the purpose of this study.

Machining Characteristics of Micro Structure using Single-Crystal Diamond Tool on Cu-plated Mold

The optical film for light luminance improvement of back light unit that is used in light emitting diode/liquid crystal display and retro-reflective film is used as luminous sign consist of square and triangular pyramid structure pattern based on V-shape micro prism pattern. In this study, we analyzed machining characteristics of Cu-plated flat mold by shaping with diamond tool. First, cutting conditions were optimized as V-groove machining for the experiment of micro prism structure mold machining with prism pattern shape, cutting force and roughness. Second, the micro prism structure such as square and triangular pyramid pattern were machined by cross machining method with optimizing cutting conditions. Variation of Burr and chip shape were discussed by material properties and machining method.

3606 金属ガラス製マイクロ構造部品の精密成形(S60 超精密・微細加工,S60 超精密・微細加工)

Recently, more miniaturization and higher integration of LSI are required and the size of electrode pad on LSIs has become narrower. In the manufacturing process of LSI, the electric property has to be checked with IC probes by contacting the probe to check and the size and pitch of the probes are also required to be smaller. In this study, it paid attention to the metallic glass in order to develop smaller probes. The metallic glass is a metal with an amorphous structure and it has an excellent character for the spring material as follows: high strength and high elasticity limit Moreover, the size effect of metallic glass is small because it is an isotropic and a homogeneous material. It can be mold by the glass molding process. In the experiments, metallic glass was molded by using flat surface molds and structured molds with V-shaped micro grooves as the basic experiment.

Effect of variations in thermophysical properties and design parameters on the performance of a V-shaped micro grooved heat pipe

The paper presents a detailed simulation of a V-shaped micro heat pipe. The effect of the substrate temperature on the model has been considered. A new method for calculating dry-out length has been proposed. The sensitivity of the model to variations in thermophysical properties and design parameters has been studied. The variations in the contact angle for the substrate–coolant liquid system, surface tension and viscosity of the coolant liquid, inclination, groove angle, length of adiabatic section and radius of ungrooved substrate have been considered. The effect of design and operating parameters on the performance of the heat pipe has been studied. The variations in contact angle have been found to significantly affect the performance of a micro heat pipe. The performance of a micro heat pipe is susceptible to ungrooved area of a V-shaped micro heat pipe. If the groove is not sharp enough i.e., the radius of ungrooved substrate is more; the micro heat pipe may cease to work even before it reaches its other operating limits. The various sensitivity studies made in this work gives better understanding of variations in thermophysical properties and design parameters of a micro heat pipe.

Creation of Ultraprecision V-shaped Micro Grooves with Flat-end

Creation of Ultraprecision V-shaped Micro Grooves with Flat-end

Capillary Performance of Evaporating Flow in Micro Grooves: An Analytical Approach for Very Small Tilt Angles

The axial flow of an evaporating thin film through a V-shaped micro channel was investigated for the case of a grooved plate inclined with a very small tilt angle. For this problem, the addition of the gravity term caused by the tilt angle alters the form of the governing equation from linear to nonlinear. Because the effect of the tilt angle is very small, a perturbation method was applied to obtain a first order perturbation solution of R = R0 + εR1, where R0 is the undisturbed solution caused by the tilt angle. A generalized graph of the nondimensional radius of curvature as a function of the nondimensionalized axial length was obtained. The perturbation parameter, ε, was expressed as a function of five nondimensional parameters. The results indicate that when the geometry is fixed, the effects of the Bond number and Capillary number are dominant. In addition, it was found that ε is inversely proportional to the square root of the Capillary number. This indicates that the perturbation method is applicable and accurate, even for the case of somewhat larger tilt angles (where the initial applicability of perturbation appears to be violated), is a sufficiently large heat flux is applied.

ESTIMATION OF SCALE OF SLOPE FAILURE TAKING ACCOUNT OF DISTRIBUTION OF SUB-SURFACE FLOW DEPTH

Stability analysis of slope, based on the assumption of uniform field, cannot estimate two-dimensional scale of failure. On the other side, the depth of sub-surface flow which is highly related to slope failure is never considered uniform at natural slope. Paticularly, at a V-shaped micro configuration of the ground, the rise of sub-surface flow depth must be rapid and the failure will occur first at there. This paper proposes a model which estimates two-dimensional scale of failure occurred at such a not uniform field. The model consists of two parts, one is configuration model as shown in Fig. 1-Fig. 3 and one is stability analysis model. The stability analysis model is based on circular arc method, which introduces cohesion on the side of circular arc in addition to the bottom of the arc.

Antifriction effect of grooves in bearings

The paper presents a detailed simulation of a V-shaped micro heat pipe. The effect of the substrate temperature on the model has been considered. A new method for calculating dry-out length has been proposed. The sensitivity of the model to variations in thermophysical properties and design parameters has been studied. The variations in the contact angle for the substrate–coolant liquid system, surface tension and viscosity of the coolant liquid, inclination, groove angle, length of adiabatic section and radius of ungrooved substrate have been considered. The effect of design and operating parameters on the performance of the heat pipe has been studied. The variations in contact angle have been found to significantly affect the performance of a micro heat pipe. The performance of a micro heat pipe is susceptible to ungrooved area of a V-shaped micro heat pipe. If the groove is not sharp enough i.e., the radius of ungrooved substrate is more; the micro heat pipe may cease to work even before it reaches its other operating limits. The various sensitivity studies made in this work gives better understanding of variations in thermophysical properties and design parameters of a micro heat pipe.