Papers by Keyword: Diffraction

Abstract: The measurement of erythrocyte size was studied by using diffraction technique base on laser. The light from a diode laser was observed with 650 nm and 532 nm of light wavelength through erythrocyte on the slide. The result found that the ring was appeared on the screen alternate with brightness and dark. The first brightness radius was measured on the screen (Y) and the distance of the position of the slide erythrocytes to screen (X) was observed then calculated the diameter of an erythrocyte (d) in microns (μm). The above number were calculated the volume of erythrocyte and compared with automatically complete blood count (CBC) machine by the mean corpuscular volume (MCV) with femtolitre (fl) values​ in the range 60-100 femtolitre. In conclusion, this study showed that the sizes of erythrocyte by laser diffraction technique are similar with the automated blood count. Therefore, it can be applied to measure erythrocyte size.

Abstract: Two-dimensional films of graphene oxide (GO) have been synthesized using various oxidation methods such as the conventional or modified Hummers method. The redox method for graphite has shown promise at producing GO films on a large scale. However, this method is a very exothermic process that liberates gases that are harmful to the environment and humans. This article addresses the characterization of graphene oxide from alternative sources of carbon and using the dry method. Comparative studies performed using Raman spectroscopy suggest that this method is both promising and more environmentally friendly.

Abstract: An optimization method for fabricating 3D microneedle arrays with larger cone angles through backside exposure is demonstrated in this paper. A photo mask was designed to fabricate SU-8 microneedle based on diffraction of UV light. A circular hole diffraction was simulated with Matlab to obtain light intensity distribution. The simulation results show that the cone angles and surface profile can be adjusted by changing the thickness of substrate and exposure dose. Based on the simulation results, the microneedles with heights of 265 μm to 380 μm and cone angles in the range of 5.1° to 15.6° were fabricated by the backside exposure technology through one time UV lithography. Compared with previous approaches, the fabrication process in this paper takes advantages of simple, low cost and mass production.

Abstract: In order to gain control over hard X-ray (over 30 keV), we have considered the X-ray diffraction in Laue geometry (over 30 keV) from a single crystal of quartz influenced by the temperature gradient. It was experimentally proved that the intensity of the reflected beam can be increased up to 35 times if the X-ray energies are 30 keV and keV for reflecting atomic planes () depending on the value of the temperature gradient. As the temperature gradient increases, the focus moves closer to the crystal and the focal spot shrinks in the diffraction plane.

Abstract: Recently the demand of sloshing analysis is rising for building FLNG (Floating Liquefied Natural Gas) vessel. This study considers the experimental and numerical observations on strongly nonlinear sloshing flows in ship motion. The FLNG (Floating Liquefied Natural Gas) vessel was considered to be rigid body supported by non-permanent pole with distributed spring damper. Based on the general equation of the ship motion in waves, and various wave amplitude, various heading, wave period and critical fluid level on the cargo tank period governing equation induced by sloshing were derived. Several physical issues are introduced in the analysis of sloshing flows, and the corresponding numerical models are described. To study the sloshing effects on ship motion, a ship motion program based on impulsive response function (IRF) is coupled with the developed numerical models for sloshing analysis. The results show that the nonlinearity of sloshing-induced forces and moments plays a critical role in the coupling effects.

Abstract: Detonation is the supersonic mode of combustion process which is essential for energy release from combustion process. Detonation is the more energetic process compare to deflagration mode of combustion process. The turbulence combustion flame cannot transit itself into detonation combustion process. So objective of this paper is to investigate the effect of obstacles configuration landed in detonation tube channel to propagate the detonation wave and diffraction encounters in an obstacles site. Four different cases of obstacles blockage ratio (BR) 0.4, 0.5, 0.6 and 0.7 were studied for detonation flame acceleration in detonation tube. A three dimensional computational simulation was done using unsteady green-gauss cell based solver for adopting the combustion simulation. As a result detonation flame propagation, detonation flame velocity and detonation flame pressure were increase in reducing blockage ratio from 0.7 to 0.4 and eddy viscosity of combustible mixture was increase with increasing the blockage ratio. From the analyzed four blockage ratio BR=0.4 is suitable for detonation mode of combustion and flame acceleration.

Abstract: Residual stress measurement techniques can be categorized as either relaxation or diffraction methods. Practitioners often advocate a particular category and sometimes a specific technique (hole drilling, contour, XRD, neutron, etc) based on their experience or capability rather than using the best technique for the particular application. This paper considers some of the implications from applying this “drunkard’s search” or “streetlight” approach by examining examples where the critical stress could be hidden from both relaxation and diffraction measurements. A better approach to planning residual stress measurements would begin with a detailed consideration of why the stresses should be measured and how the results will be used. Only then can the most appropriate measurement plan be developed. Since a single measurement technique cannot reveal the full state of stress, especially in challenging parts, the use of multiple measurement types often provides the most useful information to customers.

Abstract: The historical Eshelby-Kröner self-consistent model is only valid in the case when grains can be assumed similar to ellipsoids aligned preferentially along a same direction into the polycrystal. In this work, distributions of crystallites morphologies and geometrical orientations were accounted for, owing to the so-called generalized self-consistent model, in order to satisfy Hills averages principles. Different nonlinear ε_φψ-vs.-sin²ψ distributions were predicted in elasticity, even in the absence of crystallographic texture, in the case when several morphologies and geometrical orientations coexist within the same polycrystal.

Abstract: The influence of the porosity of the structure on the shallow water wave-Induced seepage force on the bottom of porous vertical circular cylinder resting on porous elastic seabed has been investigated. Based on the shallow water diffracted wave theory and Biot consolidation theory on wave-induced seepage pressure, the analytical solutions to first order cnoidal wave diffraction by porous vertical circular cylinder and wave-induced seepage pressure are obtained by the eigenfunction expansion approach. Numerical results show that cnoidal wave-induced uplift and moment may have same order of magnitude as the horizontal cnoidal wave force and moment , and the body porosity of the structure may lead to a reduction both in direct cnoidal wave forces and in the cnoidal wave induced seepage moment. Compared with Airy wave theory, in certain shallow water conditions, the shallow water wave theory can more effectively reflect wave nonlinearity effect in wave load prediction.

Abstract: A conical slit cell for depth-resolved diffraction of high-energy X-rays was tested at the high-energy materials science beamline HEMS at PETRA III and used for the analysis of residual stresses in a laser beam welded steel overlap joint. With a conical slit width of 20 µm and beam cross-sections below 100 µm, depth resolutions well below 1 mm were achieved. The residual stress distributions obtained from the steel joint were in very good agreement with previous results from neutron diffraction measurements, although they were still noisier because of inferior grain statistics.