Snell's laws at the interface between nonlinear dielectrics

An equivalent particle theory is developed which is effective in capturing the global behavior of surface waves at the interface between two nonlinear dielectrics.     

Effects and mechanism of ultrasonic irradiation on solidification microstructure and mechanical properties of binary TiAl alloys

In spite of their high temperature and reactivity, the binary TiAl alloys are successfully imposed by the ultrasonic irradiation and the microstructure evolution, solidification behaviors and mechanical properties are elaborately investigated. After ultrasonic irradiation, a high quality ingot without shrinkage defects and element segregation is obtained and the coarse dendrite structure is well modified into fine non-dendrite globular grains. The coarse lamellar colony and lamellar space of Ti44Al alloy is refined from 685 μm to 52 μm and 1185 nm to 312 nm, respectively (similarly, 819 μm to 102 μm and 2085 nm to 565 nm for Ti48Al alloy). For Ti48Al alloy, the α peritectic phase is simultaneously precipitated from the melt as well as the β primary phase before the peritectic reaction and the solidification is transformed into the mixed α-solidifying and β-solidifying. Ultrasonic irradiation promotes the peritectic reaction and phase transformation completely and the phase constituent becomes more close to the equilibrium level. The compressive strength of Ti44Al and Ti48Al alloys are increased from 623 MPa to 1250 MPa and 980 MPa to 1295 MPa, respectively. The grain refinement and dendrite transformation enhance the grain boundary sliding improving the plastic deformation ability. Ultrasonic irradiation significantly accelerates the melt flow and solute redistribution and the main grain refinement mechanism is the cavitation-enhanced nucleation by inclusion activation and heightened supercooling.     

Propagation properties of TE-mode soliton in rectangular waveguides with nonlinear dielectrics

The problem of rectangular waveguide with nonlinear dielectrics is discussed. The components of electromagnetic fields in the waveguide satisfy nonlinear partial differential equations. Using slowly varying envelope approximation, they can become well known nonlinear Schrodinger equation and soliton solution is got from the equation.     

Measurement of the electrical properties of dielectrics and semiconductors by means of a transcritical-waveguide cavity

A transcritical-waveguide cavity with a transverse pin can be used to measure the electrical properties of dielectrics and semiconductors. The corresponding relations are derived. This method is suitable for measurements in the decimeter and centimeter ranges and can be used with extremely small samples.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 88–91, January, 1971.     

Improved mechanical properties of retorted carrots by ultrasonic pre-treatments

The use of ultrasound pre-processing treatment, compared to blanching, to enhance mechanical properties of non-starchy cell wall materials was investigated using carrot as an example. The mechanical properties of carrot tissues were measured by compression and tensile testing after the pre-processing treatment prior to and after retorting. Carrot samples ultrasound treated for 10 min at 60 °C provided a higher mechanical strength (P < 0.05) to the cell wall structure than blanching for the same time period. With the addition of 0.5% CaCl₂ in the pre-treatment solution, both blanching and ultrasound treatment showed synergistic effect on enhancing the mechanical properties of retorted carrot pieces. At a relatively short treatment time (10 min at 60 °C) with the use of 0.5% CaCl₂, ultrasound treatment achieved similar enhancement to the mechanical strength of retorted carrots to blanching for a much longer time period (i.e. 40 min). The mechanism involved appears to be related to the stress responses present in all living plant matter. However, there is a need to clarify the relative importance of the potential stress mechanisms in order to get a better understanding of the processing conditions likely to be most effective. The amount of ultrasound treatment required is likely to involve low treatment intensities and there are indications from the structural characterisation and mechanical property analyses that the plant cell wall tissues were more elastic than that accomplished using low temperature long time blanching.     

超声无铆静力学性能强化试验与机制研究*

无铆连接是一种薄板材料连接新技术,可在无需预成孔和表面预处理情况下,实现同种、异种、多层薄板材料高效连接,但由于无铆接头静力学性能较低,极大地限制了该连接技术的推广与发展。为解决这一难题,本文选用5A06铝合金与TA1钛合金进行同种金属无铆铆接,并在此基础上进行了超声金属焊接复合实验,基于静拉伸测试和扫描电镜分析,探究超声焊对无铆接头力学性能的强化机制。试验结果表明：超声焊可有效提升无铆接头力学性能,特别是对于铝合金无铆接头;超声焊使得铝合金板塑性提高,钛合金板则得到硬化;超声焊后无铆接头的受力形式发生改变,从颈部受力变为先焊合区受力再颈部受力,这是超声焊复合强化的根本原因;超声焊可使铝合金无铆接头内部形成一定深度的固相焊,使铝合金接头力学性能得到大幅提升;TA1钛合金无铆接头内部固相焊较浅,力学性能提升相对较低。     

A new electrical to mechanical coupling effect for nonlinear piezoelectric solids

A new electrical to mechanical coupling mechanism is identified whereby electric field rates across discontinuities in strain are shown to induce strain gradients across the discontinuity.     

Investigation of the electrical conductivity of powdered dielectrics

Results are reported of an investigation into the temperature dependence of the electrical conductivity of some powdered oxides and complex oxide systems with different grain sizes and different relative density of the specimens. Using spectral analysis the transport numbers of impurity ions are determined for some powdered technical dielectrics. Such data might be useful when choosing the insulating material for tubular electrical heating elements and high-temperature cables.     

Thermal, mechanical, electrical, linear and nonlinear optical properties of a nonlinear optical l-ornithine monohydrochloride single crystal

Optically transparent semiorganic nonlinear optical bulk single crystal of l-ornithine monohydrochloride (LOMHCL) of dimension 11×3×2 mm³ has been grown from its aqueous solution by slow solvent evaporation technique. The grown crystal was characterized by powder X-ray diffraction to confirm the crystal structure. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopy technique. Thermal behavior of the grown crystals was studied by thermogravimetric analysis. The second harmonic generation (SHG) efficiency of LOMHCL was determined by Kurtz and Perry powder technique. The optical absorption study confirms the suitability of the crystal for device applications. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. Dielectric and photoconductivity studies are also carried out for the grown samples.     

Influence of proton irradiation on electrical properties of Y-Ba-Cu-O thin films

One of the authors (P. K.) wishes to express his gratitude to Dr. O. Meyer and his technical staff for providing him with the experimental facilities in the Institut für Nukleare Festkörperphysik, Karlsruhe.     

Effect of alpha-particle irradiation on the electrical properties of n-type Ge

Deep-level transient spectroscopy was used to investigate the effect of alpha particle irradiation on the electrical properties of n-type Ge. The samples were irradiated with alpha particles at room temperature using an americium-241 (Am-241) radionuclide source. The main defects introduced were found to be electron traps with energy levels at E_C−0.38, E_C−0.21, E_C−0.20, E_C−0.15, and E_C−0.10 eV, respectively. The main defects in alpha particle irradiation are similar to those introduced by MeV electron irradiation, where the main defect is the E-center. A quadratic increase in concentration as a function of dose is observed.     

Enhancing mechanical properties of prevulcanized natural rubber latex via hybrid radiation and peroxidation vulcanizations at various irradiation doses

At present, there are three popular vulcanization processes being used in natural rubber latex industries, which are sulfur, radiation and peroxide vulcanization. Sulfur vulcanization produced products with superior mechanical properties compared to radiation and peroxide vulcanization. This paper discussed the effect of gamma irradiation dose on hybrid radiation and peroxidation vulcanizations in improving the mechanical properties of radiation vulcanized natural rubber latex (RVNRL). Latex compounding formulations are developed based on 2.5?parts per hundred rubber (phr) of hexanediol diacrylate (HDDA) as the sensitizer, 0.1?phr of tert-butyl hydroperoxide (t-BHPO) as the co-sensitizer and 2.5?phr of Aquanox LP antioxidant. The RVNRL was prepared and irradiated at various gamma radiation doses of 2, 4, 6, 8, 10 and 12?kiloGray (kGy). The rubber film obtained from irradiation at 6?kGy had tensile strength, modulus @ 500% and modulus @ 700% of 27.0, 3.0 and 11.0?MPa, respectively, which is more than 37% increment compared to the control film. Besides, the crosslink percentage of the rubber film showed 4% increment from 90% to 94%.     

Rapid growth of magnetite nanoplates by ultrasonic irradiation at low temperature

Two-dimensional plate-like Fe(3)O(4) nanocrystals were synthesized by a facile method using ultrasonic irradiation in aqueous solution at low temperature without protection from oxygen. The crystals were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier Transform infrared spectroscopy. The products subjected to ultrasound showed a two-dimensional morphology. The results obtained indicate that the morphologies of the magnetite crystals depend more on the ultrasonic irradiation than on the growth temperature. The thickness and width of the crystals increased with increasing temperature of the reaction medium. In addition, the magnetic hysteresis loop of the magnetite nanoplates was obtained at room temperature.     

多组分复合薄膜的光学、电学、机械性能及其应用

复合薄膜因其可具有比单组份薄膜更加优异的性能而得到广泛的应用。通过以膜层的防护、催化、电学、光学以及力学性能等复合思想为切入点,阐述了通过膜层的复合掺杂旨在增强合金的抗腐蚀性,提高润滑摩擦性能,改善膜层的导电性能以及进行光学薄膜折射率和光谱吸收的调控,增强膜层的硬度及拉伸强度等机械性能的方法。对国内外的相关前沿成果进行简要介绍,并对复合薄膜的未来发展进行展望,为相关领域的研究提供参考。     

Reflection and transmission of circularly polarized waves in nonlinear dielectrics

A time-sinusoidal circularly polarized plane standing wave solution is obtained for isotropic lossless dielectric media with arbitrary nonlinearity. The spatial variation of the standing wave depends on the nonlinearity and is found by solving a problem of centralforce motion in which the electric complementary energy density furnishes the potential and the spatial coordinate has the role of time. Two special nonlinear dielectric response laws-cubic and quintic-are treated, and explicit solutions for the spatial variation of the wave amplitude and phase are obtained in terms of elliptic functions and elliptic integrals, respectively. The standing-wave solution is applied to give steady state solutions of two reflection/transmission problems (a) reflection from, or resonance modes between, ideally conducting planes and (b) reflection and transmission at a plane interface between two nonlinear dielectric media.     

Solvent extraction of cadmium and zinc from sulphate solutions: Comparison of mechanical agitation and ultrasonic irradiation

This research was conducted to evaluate the potential of ultrasonic irradiation during the solvent extraction of metals, and comparing its efficiency with a mechanically stirred system (MSSX). The simultaneous extraction of zinc and cadmium from sulphate solutions was investigated by di-(2-ethylhexyl) phosphoric acid (D2EHPA) as an organic extractant which was diluted (20%) in kerosene at the organic: aqueous phase ratio of 1:1 and the temperature of 25 °C. The influence of some critical parameters, including contact time, solution pH, ultrasonic power, and zinc/cadmium ratio were investigated on the extraction of the metals. Results show that D2EHPA selectively extract zinc rather than cadmium in both mechanically and ultrasonically mixed systems. It was also found that increase of ultrasonic power from 10 to 120 W cause a small decrease in zinc extraction; while, at low and high levels of the induced power, cadmium extraction was significantly decreased. Results also show that maximum extraction amounts of zinc (88.7%) and cadmium (68.2%) by the MSSX system occurred at the pH of 3 and the contact times of 3 and 20 min, respectively. Although capability of extraction in the ultrasonically assisted solvent extraction (USAX) system for both metals was higher, the selectivity was lower than that of MSSX system under different conditions especially in high zinc/cadmium ratios. It can be concluded that physical effects (i.e. mixing) inducing at low ultrasonic powers (below 60 W) mainly results in increasing solvent extraction rate, while the chemical actions applied at the higher powers have a negative outcome on the extraction rate particularly for cadmium.     

Fluctuations of electrical and mechanical properties of diamond induced by interstitial hydrogen

While experimental evidence demonstrates that the presence of hydrogen(H)impurities in diamond films plays a significant role in determining their physical properties,the small radius of the H atom makes detecting such impurities quite a challenging task.In the present work,first-principles calculations were employed to provide an insight into the effects of the interstitial hydrogen on the electrical and mechanical properties of diamond crystals at the atomic level.The migrated pathways of the interstitial hydrogen are dictated by energetic considerations.Some new electronic states are formed near the Fermi level.The interstitial hydrogen markedly narrows the bandgap of the diamond and weakens the diamond crystal.The obvious decrement of the critical strain clearly implies the presence of an H-induced embrittlement effect.