Papers by Keyword: Aspect Ratio

Abstract: This paper reports the synthesis of gold nanorod with controlled aspect ratio prepared by varying the concentration of nanoseed addition into the growth solution via seed mediated growth method. In typical process, the gold nanorod with aspect ratio from ca. 1.7 to 3.1 can be successfully obtained. The nanorod seems to be perfect rod morphology instead of bone-like or tear drop structure. Owing to the simplicity in preparing the gold nanorod, the present approach could be used as potential alternative for producing gold nanorod with special properties for used in the currently existing application.

Abstract: Crack universally existing underground is an important kind of pores. In order to study the elastic wave propagation in fractured medium through experiment, a new method to make artificial core with certain cracks using oil well cement and camphor sheet or thin steel sheet is put forward. Geometric parameters of the crack, such as shape, size and aspect ratio, are approximately equal to that of camphor sheet or thin steel sheet. Using the thin steel sheet to make crack can be more easy and accurate to control the crack angle than using camphor sheet. The crack opening scales at millimeters. The aspect ratio of cracks formed by camphor sheet ranges from 1.4 to 8, and aspect ratio of cracks formed by thin steel sheet ranges from 2.5 to 70. This method is proved simple and feasible by experiment practice, which can provide artificial cores with certain crack for acoustic wave propagation study.

Abstract: Four groups of small-scaled ethanol pool fire experiment with different aspect-ratio(s) is undertaken, to gauge the mass loss rate of fuel as well as the plume centerline temperature distribution. Comparison of plume centerline temperature is made between the theoretical values estimated by Heskestad plume model and experimental results, which indicates that: with the increasing of s, the difference between theoretical values and experimental values tend to grow greater; and when s≈1, theoretical values and experimental values cohere well.

Abstract: In this paper, the effects of delamination on critical buckling load failure of unidirectional E-glass/epoxy composite laminated plate consisting of delamination at the middle of the mid plane were studied. Experimental work was carried out to determine the buckling load for rectangular composite plates consisting of delamination for various aspect ratios ranging from 0.5 to 3. Stitched and unstitched laminates were prepared by introducing inplane delamination at the mid of the mid plane using Teflon film. These specimens were made with unidirectional fiber of orientation of (0^o/-45^o/45^o/90^o)_s with single inplane delamination at the mid of the mid plane of through width and various lengths of 130 mm and 50 mm. The Plates were made to buckle experimentally by simply supporting the top and bottom edges, and sides were kept free. Buckling load has been found from the graph. The critical buckling load is found to be increased in the stitched laminates when compared with unstitched laminates and is decreased in both stitched and unstitched laminates as the aspect ratio increases. The experimental results were validated by using commercial finite element software of ANSYS.

Abstract: The effect of the aspect ratio of micro sphere lens arrays on the optical properties of diffuser including transmittance and haze have been simulated by the LightTools software, and the results show that with the increasing of the aspect ratio, the haze rises first and drops later while the transmittance decreases all the time. Later, the mold with uniform micro sphere lens arrays arranged in regular triangle has been fabricated successfully by the ball embossing method. Then, the micro sphere lens arrays diffuser with aspect ratio of 0.19, 0.23, 0.26 and 0.29 have been made using the hot embossing method in polypropylene (PP) substrate. Last, haze and transmittance of the micro sphere lens arrays PP diffuser made are verified both by experiment and simulation and the results of experiment and simulation are consistent well.

Abstract: The internal energy of working fluid in Twin-Rotor piston engine is transmitted into mechanical energy by differential velocity movement between the couple of rotors coaxial installed. The blade piston, a part of the power transmitting mechanism, is the most important component working in the worst condition in the engine. It withstands heavy mechanical and thermal loads as working at a high rotating speed, that is to say it undertaking the explosive force straight and transmitting the power to power transmitting mechanism at the first time. So the section shape of blade piston on the rotor affects power output of the engine directly. In order to select the section shape of blade piston properly, improve output capacity and reduce the affect of deformation, models of several typical shapes of the blade piston is set up. Based on the comparison of aspect ratio, analysis and size optimization are performed. The results show that the rectangular cross-section blade piston is more efficient in power transmission with small deformation and larger torque as long as the values of aspect ratio are in a reasonable range.

Abstract: This paper discusses the microfabrication of microholes using focused ion beam and investigation of geometrical integrity of microholes. Different combination of aperture size, probe current, acceleration voltage was applied for micromachining and optimized based on taper angle. Microholes with 3.0 μm of diameter were milled according to the optimized parameter using bitmap mode. The depth range of microholes was 1.0-5.5 μm. The hole’s depth and taper angle were investigated for characterization. Each of the microholes was cross sectioned for investigation. A relationship of taper angle (θ), depth and aspect ratio were plotted. Low aspect ratio (less than 1) would give the lower taper angle and hence better integrity. Acceleration voltage of 25 kV, probe current of 41.5 pA and aperture size of 4 nm produced lower taper angle for different aspect ratio.

Abstract: The accurate prediction of warpage of injection molded parts is important to achieve successful mold design with high precision. In this study, effects of polymer-filler properties, such as filler aspect ratio (L/D), filler modulus parallel to major axis (E1) and filler modulus perpendicular to major axis (E2), on warpage displacement of automobile door were studied quantitatively by experimental investigation and numerical simulation. The numerical results are in good agreement with the experimental measurements. It is also found that: (1) the thermal displacement decreases as E1 and E2 decrease, (2) the PVT displacement is not influenced by change of L/D, E1 and E2, (3) the orientation effect displacement is neglected small when L/D=1 and E1= E2, and it also increases as L/D and E1/E2 increase.

Abstract: We present in this work a numerical study of pollutants’ dispersion resulting from a bent chimney around a cylindrical obstacle. A three-dimensional numerical model, based upon the RSM (Reynolds Stress Model) turbulence closure model was used. The adopted grid is not uniform, particularly refined near the chimney and around the cylindrical building. The domain is large enough to be able to visualize the recirculation zones and the vortices created by the building. The results obtained in three dimensional configurations make possible the description of the dynamics and mass features under different aspect rations.

Abstract: ZnO nanowires with the diameters ranging from 20 to 40 nm and lengths in the range 3-5 μm were synthesized on ITO coated glass substrate by a low temperature (80 °C) solution method. The average aspect ratio (h/r) reached 150. Owing to the van der waals force the neighborly nanowires close up to form tower-like ZnO bundles. The field emission of the ZnO bundles shows a turn-on field of 7.1 V/μm at a current density of 10 μA/cm². The threshold field is 11.3 V/μm at a current density of 10 mA/cm². The good field emission performance is attributed to the high aspect ratio and tower-like shape.