Applied Mechanics and Materials Vols. 110-116

Abstract: By using electromagnetic topology (EMT) method, this paper discusses the issue of the electromagnetic field penetration through an aperture to a cavity and coupling to a two-wire transmission line in the cavity. By representing the electromagnetic field propagation path as “tube”, and combining with transmission line theory, this paper creates the Baum-Liu-Tesche (BLT) equation of radiation coupling. Then, by employing the BLT equation, the semi-analytic solutions of the load response of the two-wire transmission line in the cavity are obtained. Numerical examples are constructed to demonstrate the validity of this technique.

Abstract: High power solid state lasers have wide applications; they have extensively attracted many attentions. When laser pumped, a lot of heat produces in it causes thermal effects such as stresses end effect and variations of refraction index. In this paper, we analytically study the thermal effects in an Nd: YAG solid state laser crystal which is pumped in longitude with a second order Gaussian (super Gaussian) profile. In this survey we neglect z derivatives of temperature distribution and also consider a statement in which thermal condition of cooler system is much more than thermal condition of laser crystal. Then we apply proper boundary conditions to probe thermal distribution function and related thermal effects. It will be shown that use of second order Gaussian profile for output beam of diode lasers is a better approximation for calculating the thermal distribution and estimating the thermal lensing than the Gaussian profile.

Abstract: A Ray Transfer Matrix (RTM) of a variable-focus elastomeric fluidic lens is explored and modeled in this paper. A HeNe (543.45nm wavelength) laser is incident on the tunable lens and the effective focal length changes are explored based on this model. Results show that there are two possible focal lengths and that focal lengths are independent of the elastomer thickness.

Abstract: With the rapid development of offshore oil and gas exploitation and production at marginal oilfields, production facilities of non-pollution oil storage underwater are sorely needed to reduce production costs. The paper gives a general outline of the modes of offshore oil Storage and the status of oil Storage technology underwater. Several modes of oil storage underwater on oil/water separation and replacement are discussed. The scheme on the monitoring system of non-pollution oil storage underwater is put forward. The study is of reference value for the development at offshore marginal oilfields.

Abstract: This paper describes the wind tunnel testing of a Blended Wing Body (BWB) with rectangular canards and twisted wing (Baseline II E2 configuration) developed in Universiti Teknologi MARA (UiTM). The experiment work was carried out in UiTM low speed wind tunnel using 1:6 scaled model of BWB at Mach 0.1. The testing is conducted for canard’s deflection angle between 0° to +20. The results show by adding the canard surface to the BWB’s body, at 12 degree and higher angles of attack,α there will be a slight increment in lift. Maximum lift-to-drag ratio decreases with increasing canard surface deflection. Also, by adding the canard surface, the value of moment at zero lift,CM,0 is increased.

Abstract: The encrypted satellite data can get corrupted before reaching the ground station due to various faults. One major source of faults is the harsh radiation environment. Single Even Upset (SEU) faults can occur on-board during encryption due to radiation. This paper presents a novel model to detect and correct Single Event Upsets in on-board implementations of the AES algorithm, which is based on Hamming error correcting code. From five modes of AES, CRT mode seems to be the best mode to encrypt satellite video and image links. A detailed analysis of the effect of SEUs on the imaging data during on-board encryption using the modes of AES is carried out. In this paper the impact of these faults on the data is discussed and compared for all the five modes of AES. A detailed analysis of the effect of SEUs on the imaging data during on-board encryption using the modes of AES is carried out.

Abstract: In this study, the energy and exergy analysis of an ideal Rankine cycle with reheat is presented. The percentage ratio of the exergy destruction to the total exergy destruction was found to be maximum in the boiler system 86.27% and then condenser and stack gas 13.73%. In addition, the calculated thermal efficiency was 38.39 % while the exergy efficiency of the power cycle was 45.85%. For improvement the power plant efficiency, parametric study has been done and the effect of boiler and reheat pressure and condenser pressure on the cycle efficiency calculated.

Abstract: Steady state creep in a anisotropic rotating disc made of Al-SiCp composite having hyperbolically varying thickness has been investigated using Hill’s yield criterion. The creep behavior is supposed to follow the Sherby’s law in present study. The stress and strain distributions are calculated for different combinations of anisotropic constants. The change in the radial stress is not significant while the tangential stress is changed with the change in the material constants. The tangential strain rates are highest at the inner radius of the disc and then decreases towards the outer radius of the disc. The radial strain rate which is compressive in nature becomes tensile in middle of the disc for some specific values of anisotropic constants. The study reveals that the anisotropy has a significant effect on the creep behavior of rotating disc. Thus for the safe design of the rotating disc the effect of anisotropy should be taken care of.

Abstract: Nonlinear free and forced oscillation of microscale simply supported beams is investigated in this paper. Introducing a material length scale parameter, the nonlinear model is conducted within the context of non-classical continuum mechanics. By using a combination of the modified couple stress theory and Hamilton’s principle the nonlinear equation of motion is derived. The nonlinear frequencies of a beam with initial lateral displacement are discussed. Equations have been solved using an exact method for free vibration and multiple times scales (MTS) method for forced vibration and some analytical relations have been obtained for natural frequency of oscillations. The results have been compared with previous work and good agreement has been obtained. Also forced vibrations of system in primary resonance have been studied and the effects of different parameters on the frequency-response have been investigated. It is shown that the size effect is significant when the ratio of characteristic thickness to internal material length scale parameter is approximately equal to one, but is diminishing with the increase of the ratio. Our results also indicate that the nonlinearity has a great effect on the vibration behavior of microscale beams.

Abstract: —In this research, the heat transfer and hydrodynamics of a gas–solid fluidized bed reactor were studied experimentally and computationally. A multi-fluid Eulerian computational model incorporating the kinetic theory for solid particles was developed and used to simulate the heat conducting gas–solid flows in a fluidized bed configuration. Momentum exchange coefficients were evaluated using the Syamlal–O’Brien drag functions. Temperature distributions of different phases in the reactor were also computed. Good agreement was found between the model predictions and the experimentally obtained data for the bed expansion ratio as well as the qualitative gas–solid flow patterns. The simulation and experimental results showed that the gas temperature decreases as it moves upward in the reactor, while the solid particle temperature increases. Pressure drop and temperature distribution predicted by the simulations were in good agreement with the experimental measurements at superficial gas velocities higher than the minimum fluidization velocity. Also, the predicted time-average local voidage profiles were in reasonable agreement with the experimental results. The study showed that the computational model was capable of predicting the heat transfer and the hydrodynamic behavior of gas-solid fluidized bed flows with reasonable accuracy.