New fast spectral analysis method for solid materials

We propose a new fast method for direct spectral analysis of solid materials based on laser ablation of the sample in deionized water and real-time transport of the aqueous suspension of nanoparticles into the inductively coupled plasma of an emission spectrometer. As a result, we have all the instrumental and methodological advantages of standard equipment, along with calibration of the spectrometer using standard aqueous solutions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 281–282, May–June, 2007.     

Electrostatic discharge sensitivity and electrical conductivity of composite energetic materials

Composite energetic material response to electrical stimuli was investigated and a correlation between electrical conductivity and ignition sensitivity was examined. The composites consisted of micrometer particle aluminum combined with another metal, metal oxide, or fluoropolymer. Of the nine tested mixtures, aluminum (Al) with copper oxide (CuO) was the only mixture to ignite by electrostatic discharge. Under the loose powder conditions of these experiments, the Al–CuO minimum ignition energy (MIE) is 25 mJ and exhibited an electrical conductivity two orders of magnitude higher than the next composite. This study showed a similar trend in MIE for ignition triggered by a discharged spark compared with a thermal hot wire source.     

Acousto-optic deflector: A new method to increase the efficiency and bandwidth

A new type of acousto-optic deflector based on anisotropic diffraction in paratellurite crystal is developed. Specific features of the method and proposed device are related to the broadening of the angular scanning range at a relatively high diffraction efficiency. The method is based on the application of the properties of the Bragg diffraction at phase modulation indices of 3π. Significant broadening of the frequency band at a relatively high diffraction efficiency is observed at high phase-modulation indices. Simultaneous application of indices of π and 3π allows a decrease in the control power to practically acceptable levels that provide continuous operation.     

A new method to study complex materials in solid state chemistry: application to chalcogenide materials

We show that a combined application of Mössbauer spectroscopy and other experimental tools such as X‐ray photoelectron spectroscopy, X‐ray absorption spectroscopy and nuclear magnetic resonance provides a coherent picture of the local electronic structure in chalcogenide materials. In order to develop this idea we propose an analysis of the Sn, Sb and Te local electronic structures for three different systems of materials. The first example concerns the In–Sn–S system. We show that Li insertion in In₁₆Sn₄S₃₂ leads to changes of the Sn oxidation states from Sn(IV) to Sn(II). The second example concerns materials of the Tl–Sb–S system. We show that variations of the ¹²¹Sb Mössbauer isomer shift and surface of the first peak of the X‐ray absorption spectra at the Sb L_III edge can be linearly correlated because of the main influence of the Sb 5s electrons. This is explained by changes in the local environment of the Sb atoms. The last example concerns the crystalline phases of the Tl–Sn–Te system. The formal oxidation numbers of the Te atoms are determined from ¹²⁵Te Mössbauer spectroscopy and X‐ray photoelectron spectroscopy. They are related to the different types of bonds involving the Te atoms in the Tl–Sn–Te compounds.     

Visualization of flow structure around a hypersonic re-entry capsule using the electrical discharge method

The spatial flowfield around a model of the re-entry capsule of the Mars Environmental Survey (MESUR) Pathfinder probe afterbody configuration traveling at a speed of Mach 10 was investigated utilizing the electrical discharge method. The shock shape ahead of the capsule was observed using a technique for visualizing 3-D shock shapes, then the streamline following the shock wave was observed utilizing a technique for visualizing streamlines crossing a shock wave. Subsequently, the flowfield behind the capsule was observed by applying a technique for visualizing flow patterns. From these observations, the spatial flow construction including the wake region such as a separation, free shear layer, and rear stagnation location behind the capsule was made clear. These experiments utilizing the electrical discharge method qualitatively demonstrated the spatial flow structure before and behind the hypersonic re-entry capsule, which had been very difficult to visualize. These experiments were carried out by using a pulsed facility of 18 ms duration.     

Optical strength of polymer materials subjected to laser ablation-induced destruction

Laser ablation-induced destruction of polymethyl methacrylate, epoxy compound, and styrosyl is studied experimentally. The values of the threshold energy density of this destruction are measured for each sample at the laboratory laser ablation station. Methods for estimating and predicting the optical strength of polymer materials are developed on the basis of a statistical model of laser ablation-induced destruction.     

Model of workpiece erosion for electrical discharge machining process

The previously published step-wise model (SWM) of cold electrodes erosion of electric arc heaters (EAHs) was modified for the calculation of workpiece removal rate (WRR) in electrical discharge machining (EDM) process. Modified model applies both relations the step-wise erosion model and the point heat source erosion model and takes into account the discharge current, the discharge pulse/pause time and thermophysical properties of machined material. The results of calculations show a reasonable agreement with data obtained experimentally by different authors about different materials and conditions.     

Analysis of applying isotropic and anisotropic destruction criteria in simulating the destruction of anisotropic materials

A comparison of the results of the numerical simulation of anisotropic material destruction (using the example of the D16T aluminum alloy) at dynamic loading obtained using isotropic and anisotropic destruction criteria is presented. The Mises-Hill destruction criterion allowing for the anisotropy of a material’s ultimate strength is used as an anisotropic criterion of destruction. For the sake of comparison, the destruction of an anisotropic material at 6.5% accumulated plastic deformation is simulated as well.     

提高灯泵钛宝石激光器效率的技术途径

介绍了几种提高灯泵钛宝石激光器效率的技术途径,包括脉冲氙灯参数的选取,放电电流的优化,泵浦腔几何结构的设计,光学谐振腔参数的优化和输出耦合镜最佳透过率的选取。通过以上各项技术的完善,激光效率得到明显提高,从０．５％到２％［１］。     

Determination of solid materials rigidity modulus by a new nondestructive optical method

We propose a new optical method for the determination of the rigidity modulus G of solid materials. The rigidity modulus is determined by measuring the twisted angle θ as a response of the material sample, depending on the applied force. The measuring of this twisted angle can be carried out by using an adapted polarimetric sensor. The effective measurement of rigidity modulus G for aluminum, Plexiglas and steel was experimentally obtained 1.4464×10¹⁰,0.99417×10⁹ and 1.0395×10¹¹ N m, respectively. The study has demonstrated the effective usefulness of our method for evaluating the rigidity modulus. A good agreement between the theoretical and experimental results was achieved.     

Measurement of effective specific heat of packed bed materials by the continuous flow electrical method

The theory of the continuous flow electrical method for the determination of specific heat of liquids has been extended to the measurements of effective specific heat of packed bed materials consisting of solid-liquid phase systems. Experimental data are reported showing the variation of effective specific heat with mass porosity and saturating liquid specific heat. The weighted arithmetic mean equation of constituent specific heats is in fair agreement with the measured values.     

How to increase S/N ratio by 10:1 in FIR transmission spectroscopy of high extinction index materials

To obtain transmission spectra of materials with a high index of extinction is very difficult in the far IR for metals, superconductors, some ferroelectrics, etc. because films as thin as 300 Å are often transmitting less than 1%. It is shown that sticking the film onto a transparent plate and looking at the interference fringes can multiply transmission by a factor of 10 or more.     

Completeness of evaporation for a powder blown into an electrical discharge

The degree of evaporation increases with the duration of the individual discharges. Suggestions are made on ways of adjusting the degree of evaporation via the various conditions.     

Multi-beam method to increase the stability of bridge deflection measurement

The main limitation to the accuracy of the detection of a bridge deflection using laser-based optical solutions is atmospheric turbulence because of the laser beam propagation in ground proximity. The multi-beam method is presented to increase the stability of bridge deflection measurement. It is based on the use of a four-beam optical system and a subpixel resolution algorithm for the measurement of the deflection of a laser beam that propagates through the system. To obtain accurate results, different algorithms for measuring the position of the deflected beam in different optical systems are tested and compared. Based on this comparison, the four-beam method based on the macropixels iteration centroid and four-beam optical system is selected, and an accuracy of 0.16 pixels is obtained by the determination of the beam position in our setup. The proposed method is adopted to detect the bridge deflection and an accuracy of 0.01 mm is gained when the scintillation index C_n² is 3×10⁻⁴ m^−2/3.     

Use of solid-phase inhomogeneities to increase the efficiency of ultrasonic therapy of oncological diseases

Authors’ concepts on the use of solid-phase sonosensitizer nanoinclusions in biological structures as ultrasonic energy concentrators in the therapy of oncological diseases are developed. The possibility of directed synthesis of nanoparticles and their aggregates in tumor tissue depending on its growth features is discussed. It was found that acoustic effects in polymer structures containing solid-phase inclusions depend on the nature of these inclusions and their bond with the polymer matrix. Using model gel systems, it was shown that solid-phase sonosensitizers enhance local thermal effects and amplitude-dependent scattering of ultrasound during its propagation in gel. Experimental studies on animals showed that the ultrasound exposure of malignant tumors containing nanoparticles of gold and some complex compounds results in a significant therapeutic effect.     

采用坡度磁场提高同轴腔电子回旋管的效率

通过选择适当电子初始的横纵向速度比,并引进坡度磁场的方法,来提高同轴腔电子回旋微波激射器效率。非线性模拟表明,用这种办法可以将德国卡尔斯鲁研究中心研制的同轴腔电子回旋微波激射振荡器的实验效率,从26.7%提高到31.5%。这种效率放大的物理机制是：坡度磁场改变了相对论电子的运动条件,有效地改善了波束互作用过程中电子的群聚状态,使电子束有更多的动能转换为电磁能,从而提高了电子束的换能效率。     

采用坡度磁场提高同轴腔电子回旋管的效率

 通过选择适当电子初始的横纵向速度比，并引进坡度磁场的方法，来提高同轴腔电子回旋微波激射器效率。非线性模拟表明，用这种办法可以将德国卡尔斯鲁研究中心研制的同轴腔电子回旋微波激射振荡器的实验效率，从26.7%提高到31.5%。这种效率放大的物理机制是：坡度磁场改变了相对论电子的运动条件，有效地改善了波束互作用过程中电子的群聚状态，使电子束有更多的动能转换为电磁能，从而提高了电子束的换能效率。     

Mathematical method to predict the diffraction efficiency of holograms

In this paper, a method is presented which uses a multi-factorial decision model of fuzzy-set theory to predict the diffraction efficiency of holograms. A prediction fitting rate of 85% has been obtained. This method can be used as a guide to processing holograms.