Gauge Coupling Constants as Residues of Spacetime Representations

The gauge coupling constants in the electroweak standard model can be written as mass ratios, e.g. the coupling constant for isospin interactions with the mass of the charged weak boson and the mass parameter characterizing the ground state degeneracy. A theory is given which relates the two masses in such a ratio to invariants which characterize the representations of a noncompact nonabelian group with real rank 2. The two noncompact abelian subgroups are operations for time and for a hyperbolic position space in a model for spacetime, homogeneous under dilation and Lorentz group action. The representations of the spacetime model embed the bound state representations of hyperbolic position space as seen in the nonrelativistic hydrogen atom. Interactions like Coulomb or Yukawa interactions are described by Lie algebra representation coefficients. A quantitative determination of the ratio of the invariants for position- and time-related operations, determined by the spacetime representation, gives the right order of magnitude for the gauge coupling constants.     

Determination of volatile residual solvents in pharmaceutical products by headspace liquid-phase microextraction gas chromatography-flame ionization detector

This paper demonstrates headspace liquid-phase microextraction (HS-LPME) as used for the determination of volatile residual solvents in pharmaceutical products. This method is based on headspace liquid-phase microextraction capillary column gas chromatography. Under optimum conditions, the linerary of the method ranged from 1 to 1,000 mg l⁻¹. The limits of detection are 0.2–2.0 mg l⁻¹ and relative standard deviations (RSD) for most of the volatile solvents were below 10%. This novel method is applied to the analysis of volatile residual solvents in pharmaceutical products with satisfactory results.     

一种岩石断裂韧度试样应力强度因子的三维边界元法标定

用三维边界元法(BEM)标定了一种岩石断裂韧度试样的柔度,求出了这种试样的平均无量纲应力强度因子(SIF),并得到了对应于最大载荷时的临界裂纹长度和平均无量纲SIF的最小值.     

Effect of laser energy on the deformation behavior in microscale laser bulge forming

Microscale laser bulge forming is a high strain rate microforming method using high-amplitude shock wave pressure induced by pulsed laser irradiation. The process can serve as a rapidly established and high precision technique to impress microfeatures on thin sheet metals and holds promise of manufacturing complex miniaturized devices. The present paper investigated the forming process using both numerical and experimental methods. The effect of laser energy on microformability of pure copper was discussed in detail. A 3D measuring laser microscope was adopted to measure deformed regions under different laser energy levels. The deformation measurements showed that the experimental and numerical results were in good agreement. With the verified simulation model, the residual stress distribution at different laser energy was predicted and analyzed. The springback was found as a key factor to determine the distribution and magnitude of the compressive residual stress. In addition, the absorbent coating and the surface morphology of the formed samples were observed through the scanning electron microscope. The observation confirmed that the shock forming process was non-thermal attributed to the protection of the absorbent coating.     

Numerical simulation of instantaneous flow structure of swirling and non-swirling coaxial-jet particle-laden turbulence flows

A subgrid scale two-phase second-order-moment (SGS-SOM) model based on the two-fluid continuum approach is presented for the analysis of the instantaneous flow structures of swirling and non-swirling coaxial-jet particle-laden turbulence flows. Since the interaction between the two-phase subgrid scale stresses and the anisotropy of two-phase subgrid scale stresses is fully considered, it is superior to the conventional subgrid scale model on the basis of single gas phase or together with their similar forms for the particle phase for not taken these characters thoroughly into account. The swirling numbers s=0.47 and s=0 of coaxial-jet particle-laden turbulence flows (measured by M. Sommerfeld, H.H. Qiu, Detailed measurements in a swirling particulate two-phase flow by a phase Doppler anemometer, Int. J. Heat Fluid Flow 12 (1991) 20-28) are numerically simulated by large eddy simulation using this model, together with a Reynolds-averaged Navier-Stokes model using the unified second-order-moment two-phase turbulence model (RANS-USM). The instantaneous results show that the multiple recirculating gas flow structure is similar to that of single-phase swirling flows; but the particle flow structure contains less vortices. Both SGS-SOM and RANS-USM predicted that the two-phase time-averaged velocities and the root-mean-square fluctuation velocities are validated and are in good agreement with the experimental results. It is seen that for the two-phase time-averaged velocities both the models give almost the same results, hence the RANS-USM modeling is validated by large eddy simulation. For the two-phase root-mean-square fluctuation velocities the SGS-SOM results are obviously better than the RANS-USM results.     

Phase-field modeling droplet dynamics with soluble surfactants

Using lattice Boltzmann approach, a phase-field model is proposed for simulating droplet motion with soluble surfactants. The model can recover the Langmuir and Frumkin adsorption isotherms in equilibrium. From the equilibrium equation of state, we can determine the interfacial tension lowering scale according to the interface surfactant concentration. The model is able to capture short-time and long-time adsorption dynamics of surfactants. We apply the model to examine the effect of soluble surfactants on droplet deformation, breakup and coalescence. The increase of surfactant concentration and attractive lateral interaction can enhance droplet deformation, promote droplet breakup, and inhibit droplet coalescence. We also demonstrate that the Marangoni stresses can reduce the interface mobility and slow down the film drainage process, thus acting as an additional repulsive force to prevent the droplet coalescence.     

Surface adhesion between hexagonal boron nitride nanotubes and silicon based on lateral force microscopy

This study presents the surface adhesion between hexagonal boron nitride nanotube (BNNT) and silicon based on lateral manipulation in an atomic force microscope (AFM). The BNNT was mechanically manipulated by the lateral force of an AFM pyramidal silicon probe using the scan mechanism in the imaging mode. With a controlled normal force of the AFM probe and the lateral motion, the lateral force applied to the BNNT could overcome the surface adhesion between BNNT and silicon surface. The individual BNNT is forced to slide and rotate on the silicon surface. Based on the recorded force curve, the calculated shear stress due to surface adhesion is 0.5 GPa. And the specific sliding energy loss is 0.2 J/m². Comparing BNNTs and carbon nanotube (CNT), the shear stress and specific sliding energy loss of BNNT are an order of magnitude larger than that of CNT. Therefore, the results show that the surface adhesion between BNNT and silicon surface is higher than that of CNT.     

Elastic-plastic analyses on the residual stresses and curvature of the film/substrate bilayer system

During thermal cycling, the residual stresses are often generated in the film/substrate bilayer due to the material mismatch between the substrate and the film. If the thickness of the film is relatively high, the thermal residual stresses in it may be of different signs. When the film is subjected to elastic-plastic deformation, two plastic zones with different thicknesses may be generated in the film at a significantly high temperature difference. In this paper, a theoretical model which reflects the complete history of thermal residual stresses and curvatures in the elastoplastic film/substrate bilayer system is developed. Solutions are derived to estimate the residual stresses and curvature in the film as functions of temperature difference. The case of Al/Si system is used to illustrate the implementation of this model. Results show that the critical temperature difference at which the second plastic zone near the film surface is generated near the Al film surface is dependent on the film thickness. The strain hardening of the film has an obvious influence on the magnitude of residual stresses within the film at high temperature difference.     

Laser Shock Processing of 6061-T6 Al alloy with 1064 nm and 532 nm wavelengths

Laser Shock Processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results in the LSP concept for metal surface treatments in underwater laser irradiation at 532 nm and 1064 nm. The purpose of the work is to compare the effect of both wavelengths on the same material. A convergent lens is used to deliver 1.2 J/pulse (1064 nm) and 0.9 J/pulse (532 nm) in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG laser with spots of a 1.5 mm in diameter moving forward along the work piece. A LSP configuration with experimental results using a pulse density of 2500 pulses/cm² and 5000 pulses/cm² in 6061-T6 aluminum samples are presented. High level compressive residual stresses are produced using both wavelengths. It has been shown that surface residual stress level is comparable to that achieved by conventional shot peening, but with greater depths. This method can be applied to surface treatment of final metal products.