Analysis of sound radiation characteristics of complex double shells

The double stiffened shell connected by annular plates is systematically studied.The shell motion is obtained using the classical Fliigge operator, the effects of stiffeners are induced into the vibration equation by treating them as reverse included in forces and moments on the shell, and the fluid field between the inner shell and outer shell is solved by applying Helmholtz equation and the continuity conditions of the displacement on the surface of fluidstructure. At last the vibration equation coupled by the sound-fluid-structure are constituted and solved. The effects of the double shell parameters and linked types between the double shells on the sound radiation are discussed in detail. The following conclusions can be gotten:The smaller the space between the inner shell and outer shell, the stronger the coupling of the inner shell and outer shell, the higher the radiated power and radial quadratic velocity, and the more indistinct the shield of the outer shell. The changes of the thickness of the inner shell and outer shell influenced the radial quadratic velocity greatly, and influenced the radiated power indistinctly. The thicker the thickness, the lower the radial quadratic velocity.     

Inverse problem of ship propeller cavitationnoise radiation

I.IntroductionInthecourseofnavigation,shipsinevitablyproducevariouskindsofnoiseradiation,whichbringusimportantinformation.Ononehand,manyresearchersdevotethemselvestothestudyofthetime-frequency-amplitudedomaincharacteristicsoftheshipnoiseradiationfield,whichistheregularmethodforstudyingthenoiseradiation,i.e.,thedirectproblem.ontheotherhand,theyareworkinghardatmakinguseofthelloiseradiationtoinferthestateofshipnavigationandtheconditionofthemainaPparatusonboard,etc.,andthisistheinverseproblemofthe…     

Quantum tunnelling radiation of Einstein-Maxwell-Dilaton-Axion black hole

By taking the energy conservation and angular momentum conservation into account, the characteristics of the quantum-tunnelling radiation of Einstein--Maxwell--Dilaton--Axion black hole are studied and the result shows that the tunnelling rate of such a black hole is relevant to Bekenstein--Hawking entropy and that the obtained radiation spectrum is not pure thermal.     

Interaction of 3μm radiation with matter

Drilling of small holes into media containing O-H or C-H bonds with a 2.92m YAIO₃-Er laser is studied. In materials containing O-H bonds strong absorption allows small volumina to be heated with only marginal heat diffusion. Drilling with nearly diffraction-limited lateral resolution is achieved.     

Dynamics of the Earth’s radiation belts

In this article, we provide a short review of the current state of the field of the radiation belts of the Earth. The main attention is given to the variations of energetic particle fluxes during geomagnetic storms. Electron and proton acceleration mechanisms in the terrestrial magnetosphere are discussed. The possibility of predicting various space weather parameters using the data on relativistic electrons of the outer radiation belt is discussed.     

Polarization of Čerenkov radiation in anisotropic media

Using the method of Stokes parameters, we examine the polarization of erenkov radiation in anisotropic media. The study reveals that the radiation is totally polarized and that circular polarization is purely a quantum effect. We examine two cases: when the particle initially moves along the optical axis and when the particle initially moves perpendicular to the optical axis.     

Study ofγ radiation from100Pd decay

This paper presents a study of the rays from the electron capture decay of 3.63d ¹⁰⁰Pd. Singles and coincidence measurements provided an accurate determination of-ray intensities and an improved knowledge of the¹⁰⁰Rh level scheme. Experimental evidence supports excitation of levels in¹⁰⁰Rh at 86-, 136- and 154 keV, not previously reported from the decay of¹⁰⁰Pd.On leave from Departamento de Fisica, Comision Nacional de Energia Atomica, Buenos Aires, Argentina     

Development of infrared spectral radiation measurement system of a non-luminous flame

Flame radiation is an important parameter in combus-tion diagnostics. Prom the investigation of flame radia-tion, quantitative flame parameters, such as local tem-peratures and species concentrations along the path ofrays, can be derived. Thereby one can improve fuel per-formance, combustion engine efficiency, and the chemicalreaction process[1,2].According to the difference between the radiation spec-tra of the flame, all flame is divided into luminous flameand non-luminous flame, the former …     

Research on modal analysis of structural acoustic radiation using structural vibration modes and acoustic radiation modes

Modal analysis of structural acoustic radiation from a vibrating structure is discussed using structural vibration modes and acoustic radiation modes based on the quadratic form of acoustic power. The finite element method is employed for discretisizing the structure. The boundary element method and Rayleigh integral are used for modeling the acoustic fluid. It is shown that the power radiated by a single vibration mode is to increase the radiated power and the effect of modal interaction can lead to an increase or a decrease or no change in the radiated power, moreover, control of vibration modes is a good way to reduce both vibration and radiated sound as long as the influence of interaction of vibration modes on sound radiation is insignificant. Stiffeners may change mode shapes of a plate and thus change radiation efficiency of the plate‘s modes. The CHIEF method is adopted to obtain an acoustic radiation mode formulation without the nonuniqueness difficulty at critical frequencies for three-dimensional structures by using Moore-Penrose inverse. A pulsating cube is involved to verify the formulation. Good agreement is obtained between the numerical and analytical solutions. The shapes and radiation efficiencies of acoustic radiation modes of the cube are discussed. The structural acoustic control using structural vibration modes and acoustic radiation modes are compared and studied.     

Application of μ SR to radiation damage in metals

Proton-irradiated Al, Cu and Ni foils have been investigated by the SR technique. No trapping of ⁺ has been observed in the temperature range investigated (<300 K). In Ni a temperature-independent increase of the depolarisation rate by a factor of three is found for the irradiated target. This change is attributed to field inhomogeneities produced by defects.     

Synchrotron Mössbauer source of57Fe radiation

A nonradioactive source of Mössbauer radiation is described for use in Mössbauer absorption and scattering spectroscopy. The radiation is generated by synchrotron Xrays in an iron borate single crystal set in diffraction conditions at the Néel temperature (75.3°C). Like a conventional Mössbauer source the new Synchrotron Mössbauer (SM) source emits singleline radiation of about natural linewidth, but in addition the emitted radiation is fully recoilless, highly directed and of pure linear polarization. An extremely high suppression of the electronic scattering is achieved. The latter circumstance allows one to perform Mössbauer experiments using pulsed synchrotron radiation in a steady state mode as in a normal Mössbauer measurement.The theory of the SM source is developed. First Mössbauer spectra obtained with the SM source are shown. Applications of the SM source are discussed.     

Modelling čerenkov radiation of relativistic particles in crystals

From the aspects of classical mechanics and electrodynamics, an analysis has been performed of the possible influence of the kind of charged particle trajectory on the erenkov radiation spectrum in a crystal. Results of the analytical computation are compared with the data of a computer experiment. It is shown that the influence of the particle trajectory on the erenkov radiation spectrum is insignificant in the optical frequency band. The expected effect is possible when utilizing crystals with a superlattice and by observation of radiation in the xray frequency range.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 62–67, February, 1988.The authors are grateful to S. A. Vorob'ev for supporting the research and to Yu. L. Pivovarov for stimulating and useful discussions.     

Origin of Hawking radiation: firewall or atmosphere?

The Unruh vacuum not admitting any outgoing flux at the horizon implies that the origin of the outgoing Hawking radiation is the atmosphere of a near-horizon quantum region without resort to the firewall; however, the existence of the firewall of superplanckian excitations at the horizon can be supported by the infinite Tolman temperature at the horizon. In an exactly soluble model, we explicitly show that the firewall necessarily emerges out of the Unruh vacuum so that the Tolman temperature in the Unruh vacuum is divergent in essence due to the infinitely blueshifted negative ingoing flux crossing the horizon rather than the outgoing flux. We also show that the outgoing Hawking radiation in the Unruh vacuum indeed originates from the atmosphere, not just at the horizon, which is of no relevance to the infinite blueshift. Consequently, the firewall from the infinite Tolman temperature and the Hawking radiation from the atmosphere turn out to be compatible, once we waive the claim that the Hawking radiation in the Unruh vacuum originates from the infinitely blueshifted outgoing excitations at the horizon.     

Measurement of radiation dose at the north interaction point of BEPCⅡ

The technique details for measuring radiation dose are expounded.The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation.In addition, the photon radiation level move as background for future experiments is measured by a NaI(T1) detector.     

Gravitational radiation of the Lemaître primordial atom

A non-traditional secondary quantizing of a strong gravitational field is realized. Using an earlier developed gravitational analog of the non-stationary perturbation theory it is shown that the Lema?tre primordial atom can generate hard gravitational radiation under spontaneous transitions of an effective Planckian particle in its discrete energy spectrum. Thus, the Lema?tre atom can be considered as a regular Big Bang model. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 59–65, February, 2009.     

Influence of γ radiation on the structure-sensitive properties of CuTi amorphous alloy

The influence of small doses of radiation on the structure-sensitive properties of CuTi amorphous metallic alloy (AMA) is investigated. The AMA exhibit brittle behavior. It is found that, in samples exposed to radiation, the nonlinear behavior of the load-elongation curve is more pronounced and begins sooner. A small change in the fracture morphology in these samples is observed by raster electron microscopy. The additional broadening of the first amorphous maximum and its shift on the x-ray diffraction patterns correlates with increase in the dose. The modification of the structural-relaxation processes on heating the initial and irradiated samples is traced by the acoustic-emission method. The activation energy of these processes is determined.Tomsk State Architectural and Building Academy. Translated from Izestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 55–59, August, 1994.     

Enhancement of Smith—Purcell radiation with surface-plasmon excitation

With the aid of a three-dimensional particle-in-cell code simulation,the enhancement of Smith-Purcell radiation with a surface-plasmon mode excited by a single electron bunch and by a premodulated electron beam is considered in the paper.In the simulation,the model is a grating covered by Ag film.The results demonstrate that when the surface-plasmon mode is excited by a single electron bunch,the maximum radiation occurs at an observation angle depending on the surface-plasmon frequency,and the radiation power can be enhanced more than ten times.And for pre-bunched electron beam excitation,when one of the harmonics of the bunching frequency is resonant with that of the surface-plasmon mode,the radiation power is twenty times more than that from a perfectly conducting grating excited by the same premodulated electron beam.     

Workshop on “chemical applications of synchrotron radiation”

The Asia Oceania Forum for Synchrotron Radiation Research (AOFSRR) was formally established during a one-and-a-half-day workshop held at KEK-PF (High Energy Accelerator Research Organization—Photon Factory, Tsukuba, Japan) on November 24–25, 2006. The objective of the AOFSRR is to establish a general framework of collaboration for the development of synchrotron science and technology and to promote comprehensive cooperation in the Asia and Oceania region. Under the AOFSRR framework, a range of collaborative activities will be arranged including organization of scientific collaboration meetings and exchange of information between both facilities and user communities.     

Measurement of radiation dose at the north interaction point of BEPCⅡ

The technique details for measuring radiation dose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the photon radiation level move as background for future experiments is measured by a NaI（T1） detector.