Combined Effects of Silica Filler and Its Interface in Epoxy Resin

In this paper, mechanical properties of silica-filled epoxy resin are tested. The tests show that at elevated temperatures, the material’s properties (e.g. yield stress, flow stress, etc.) vary immonotonically with filler volume fraction. Nanoindentation test results suggest that an interface region, stronger than the matrix, is formed in the materials. The formation of the interface has positive effects on the yield strengths of materials. The addition of particles in the matrix produces a large disturbance in stress distribution, leading to stress concentration in the matrix. The stress concentration has negative effects on the yield strengths of materials. The calculation demonstrates that the maximum stress in samples varies immonotonically with particulate concentration. So, the immonotonic variation of mechanical behavior of materials may be rooted in the contradictory effects of the interface region and the stress concentration caused by particulate addition.

飞行高度及设计长度对锥形流乘波体优化的影响 Altitude and Design Length Effects of Optimized Waverider Derived from Cone Flow

高超声速条件下,乘波体布局具有高升阻比特性,本文应用单纯形加速法,以最大升阻比为目标,开展了锥形流乘波体布局优化设计研究.特别是,研究了在高层大气飞行时雷诺数效应与气动特性的关系,从乘波体飞行高度与设计长度两方面探讨雷诺数对乘波体优化的影响,结果表明：给定设计马赫数和圆锥角情况下,对于最大升阻比优化乘波体,其雷诺数越小,摩擦阻力越大,而升阻比越低.

Effects of the Spanwise Characteristic Length on the Transition Feature in the Wake of a Cylinder

The transition features of the wake behind a uniform circular cylinder at Re = 200, which is just beyond the critical Reynolds number of 3-D transition, are investigated in detail by direct numerical simulations of 3-D incompressible Navier-Stokes equations. The spanwise characteris-tic length determines the transition features and global properties of the wake.

The effects of introducing ester linking groups on the flexoelectro-optic properties of symmetric bimesogens

In the chiral nematic phase, flexoelectricity can give rise to an interesting electrooptic switching effect, known as flexoelectro-optic switching. Flexoelectro-optic switching gives a fast v-shaped switching regime. Previous studies show that symmetric bimesogens are particularly suited for flexoelectro-optic switching. By introducing two ester linking groups into the molecular structure of a symmetric bimesogen, it was hypothesised that the flexoelectric properties will be enhanced significantly because of the resulting increase in the dipole moment of the molecules. This was found to be the correct; however, the inclusion of ester linking groups reduced the liquid crystallinity of the material.

Effects of Surface Microtopology and Membrane Stiffness on Kinetics of Selectin/Ligand interactions by a Modified BFP

More and more evidences come out to support that the functionality of adhesion molecules are influenced by the surface microtopology of cell carrier or substrate. Adhesive molecules usually express on the microvilli of a cell, providing a well-defined spatial configuration to mediate the adhesions to the counterpart molecules on the apposed surface.

Effects of surface roughness on airframe noise

The generation of sound by turbulent boundary layer flow at low Mach number over a rough wall is investigated by applying the theoretical model which describes the scattering of the turbulence near field into sound by roughness elements. Attention is focused on the numerical method to approximately quantify the absolute level of the roughness noise radiated to far field. Empirical models for the source statistics are obtained by scaling smooth-wall data through increased skin friction velocity and boundary layer thickness for the rough surface. Numerical integration is performed to determine the roughness noise, and it reproduces the spectral characteristics of the available empirical formula and experimental data. Experiments are conducted to measure the radiated sound from two rough plates in an open jet by four 1/2'' free-field condenser microphones. The measured noise spectra of the rough plates are above that of a smooth plate in 1-2.5 kHz frequency and exhibits encouraging agreement with the predicted spectra. Also, a phased microphone array is utilized to localize the sound source, and it confirms that the rough plates generate higher source strengthes in this frequency range. A parametric study illustrates that the roughness height and roughness density significantly affect the far-field radiated roughness noise with the roughness height having the dominant effect. The estimates of the roughness noise for a Boeing 757 sized aircraft wing show that in high frequency region the sound radiated from surface roughness may exceed that from the trailing edge, and higher overall sound pressure levels for the roughness noise are also observed.

Generation of long, laminar plasma jets at atmospheric pressure and effects of flow turbulence

Long, laminar plasma jets at atmospheric pressure of pure argon and a mixture of argon and nitrogen with jet length up to 45 fi,Hes its diameter could be generated with a DC are torch by! restricting the movement of arc root in the torch channel. Effects of torch structure, gas feeding, and characteristics of power supply on the length of plasma jets were experimentally examined. Plasma jets of considerable length and excellent stability could be obtained by regulating the generating parameters, including are channel geometry gas flow I ate, and feeding methods, etc. Influence of flow turbulence at the torch,nozzle exit on the temperature distribution of plasma jets was numerically simulated. The analysis indicated that laminar flow plasma with very low initial turbulent kinetic energy will produce a long jet, with low axial temperature gradient. This kind of long laminar plasma jet could greatly improve the controllability for materials processing, compared with a short turbulent are let.

Effects of Baffle Design on Fluid Flow and Heat Transfer in Ammonothermal Growth System of Nitrides

Efforts have been made in growing bulk single crystals of GaN front supercritical fluids using the ammonothermal method, which utilizes ammonia as fluid rather than water as in the hydrothermal process. Different mineralizers such as amide or azide and temperatures in the range of 200-600degreesC have been used to increase the solubility. The pressure is from 1 to 4 kbar. Modeling of the ammonothermal growth process has been used to identify factors which may affect the temperature distribution, fluid flow and nutrient transport. The GaN charge is considered as a porous media bed and the flow in the charge is simulated using the Darcy-Brinkman-Forchheimer model. The resulting governing equations are solved using the finite volume method. The effects of baffle design and opening on flow pattern and temperature distribution in an autoclave are analyzed. Two cases are considered with baffle openings of 15% and 20% in cross-sectional area, respectively.

Effects of Molecular Length, Ortientation and Amino Acid Mutation on Kinetics of Selectin/Ligand interactions

Receptor/ligand interactions are basic issues to cell adhesion, which are important to many physiological and pathological processes such as lymphocyte-mediated cytotoxicity, tumor metastasis and inflammatory reactionl. Selectin/carbohydrate ligand bindings have been found to mediate the fast rolling of leukocytes on activated endothelial monolayer. Kinetic rate and binding affinity constants are essential determinants of cell adhesion...

Effects of mechanical and electrical coupling on the parametric sensitivity of mode localized sensors

We compare and contrast the effects of two distinctly different mechanisms of coupling (mechanical and electrical) on the parametric sensitivity of micromechanical sensors utilizing mode localization for sensor applications. For the first time, the strong correlation between mode localization and the phenomenon of 'eigenvalue loci-veering' is exploited for accurate quantification of the strength of internal coupling in mode localized sensors. The effects of capacitive coupling-spring tuning on the parametric sensitivity of electrically coupled resonators utilizing this sensing paradigm is also investigated and a mass sensor with sensitivity tunable by over 400% is realized. ©2009 IEEE.

Effects of Translational Nonequilibrium on Performance of Flowing Chemical Oxygen-Iodine Laser

The effect of the translational nonequilibrium on performance modeling of flowing chemical oxygen-iodine lasers (COIL) is emphasized in this paper. The spectral line broadening (SLB) model is a basic factor for predicting the performances of flowing COIL. The Voigt profile function is a well-known SLB model and is usually utilized. In the case of gas pressure in laser cavity less than 5 torr, a low pressure limit expression of the Voigt profile function is used. These two SLB models imply that ail lasing particles can interact with monochromatic laser radiation. Basically, the inhomogeneous broadening effects are not considered in these two SLB models and they cannot predict the spectral content. The latter requires consideration of finite translational relaxation rate. Unfortunately, it is rather difficult to solve simultaneously the Navier-Stokes (NS) equations and the conservation equations of the number of lasing particles per unit volume and per unit frequency interval. In the operating condition of flowing COIL, it is possible to obtain a perturbational solution of the conservational equations for lasing particles and deduce a new relation between the gain and the optical intensity, i.e., a new gain-saturation relation. By coupling the gain-saturation relation with other governing equations (such as the NS equations, chemical reaction equations and the optical model of gain-equal-loss), We have numerically calculated the performances of flowing COIL. The present results are compared with those obtained by the common rate-equation (RE) model, in which the Voigt profile function and its low pressure limit expression are used. The difference of different model's results is great. For instance, in the case of lasing frequency coinciding with the central frequency of line profile and very low gas pressure, the gain-saturation relation of the present model is quite different with that of the RE model.