Методи локації місцезнаходження дефектів структури за сигналами акустичної емісії

A review of methods and algorithms for detecting spots of structural defects developing in products under load is given. These methods and algorithms are used in acoustic emission systems designed for locating the sources of acoustic radiationПриведен обзор методов и алгоритмов определения местонахождения дефектов структуры, развивающихся в изделиях при их нагружении, которые применяются в акустико-эмиссионных системах локации источников акустического излученияНаведено огляд методів та алгоритмів визначення місцезнаходження дефектів структури, що : розвиваються у виробах при їх навантаженні, які використовуються в акустоемісійних системах  локації джерел акустичного випромінюванн

Finite-Range Gravity and Its Role in Gravitational Waves, Black Holes and Cosmology

Theoretical considerations of fundamental physics, as well as certain cosmological observations, persistently point out to permissibility, and maybe necessity, of macroscopic modifications of the Einstein general relativity. The field-theoretical formulation of general relativity helped us to identify the phenomenological seeds of such modifications. They take place in the form of very specific mass-terms, which appear in addition to the field-theoretical analog of the usual Hilbert-Einstein Lagrangian. We interpret the added terms as masses of the spin-2 and spin-0 gravitons. The arising finite-range gravity is a fully consistent theory, which smoothly approaches general relativity in the massless limit, that is, when both masses tend to zero and the range of gravity tends to infinity. We show that all local weak-field predictions of the theory are in perfect agreement with the available experimental data. However, some other conclusions of the non-linear massive theory are in a striking contrast with those of general relativity. We show in detail how the arbitrarily small mass-terms eliminate the black hole event horizon and replace a permanent power-law expansion of a homogeneous isotropic universe with an oscillatory behaviour. One variant of the theory allows the cosmological scale factor to exhibit an `accelerated expansion'instead of slowing down to a regular maximum of expansion. We show in detail why the traditional, Fierz-Pauli, massive gravity is in conflict not only with the static-field experiments but also with the available indirect gravitational-wave observations. At the same time, we demonstrate the incorrectness of the widely held belief that the non-Fierz-Pauli theories possess `negative energies' and `instabilities'.Comment: 56 pages including 11 figures; significant modifications; in particular, we demonstrate the incorrectness of the widely held belief that the non-Fierz-Pauli theories should suffer from negative energies and instabilities; to appear in Int. J. Mod. Phys.

Random template placement and prior information

In signal detection problems, one is usually faced with the task of searching a parameter space for peaks in the likelihood function which indicate the presence of a signal. Random searches have proven to be very efficient as well as easy to implement, compared e.g. to searches along regular grids in parameter space. Knowledge of the parameterised shape of the signal searched for adds structure to the parameter space, i.e., there are usually regions requiring to be densely searched while in other regions a coarser search is sufficient. On the other hand, prior information identifies the regions in which a search will actually be promising or may likely be in vain. Defining specific figures of merit allows one to combine both template metric and prior distribution and devise optimal sampling schemes over the parameter space. We show an example related to the gravitational wave signal from a binary inspiral event. Here the template metric and prior information are particularly contradictory, since signals from low-mass systems tolerate the least mismatch in parameter space while high-mass systems are far more likely, as they imply a greater signal-to-noise ratio (SNR) and hence are detectable to greater distances. The derived sampling strategy is implemented in a Markov chain Monte Carlo (MCMC) algorithm where it improves convergence.Comment: Proceedings of the 8th Edoardo Amaldi Conference on Gravitational Waves. 7 pages, 4 figure

The development of RAPTA compounds for the treatment of tumors

© 2015 Elsevier B.V. Ruthenium(II)-arene RAPTA-type compounds have been extensively explored for their medicinal properties. Herein a comprehensive review of this class of compounds is provided. A discussion of the basic RAPTA structure is given together with the ways it has been modified to elucidate the key role of each part and to afford targeted derivatives. The various mechanistic studies conducted on RAPTA compounds are described and these are linked to the observed macroscopic biological properties. Ultimately, the review shows that certain RAPTA compounds display quite unique properties that point towards a clinical investigation

LISA as a dark energy probe

Recently it was shown that the inclusion of higher signal harmonics in the inspiral signals of binary supermassive black holes (SMBH) leads to dramatic improvements in parameter estimation with the Laser Interferometer Space Antenna (LISA). In particular, the angular resolution becomes good enough to identify the host galaxy or galaxy cluster, in which case the redshift can be determined by electromagnetic means. The gravitational wave signal also provides the luminosity distance with high accuracy, and the relationship between this and the redshift depends sensitively on the cosmological parameters, such as the equation-of-state parameter $w=p_{\rm DE}/\rho_{\rm DE}$ of dark energy. With a single binary SMBH event at $z < 1$ having appropriate masses and orientation, one would be able to constrain $w$ to within a few percent. We show that, if the measured sky location is folded into the error analysis, the uncertainty on $w$ goes down by an additional factor of 2-3, leaving weak lensing as the only limiting factor in using LISA as a dark energy probe.Comment: 11pages, 1 Table, minor changes in text, accepted for publication in Classical and Quantum Gravity (special issue for proceedings of 7th LISA symposium

Cosmic Swarms: A search for Supermassive Black Holes in the LISA data stream with a Hybrid Evolutionary Algorithm

We describe a hybrid evolutionary algorithm that can simultaneously search for multiple supermassive black hole binary (SMBHB) inspirals in LISA data. The algorithm mixes evolutionary computation, Metropolis-Hastings methods and Nested Sampling. The inspiral of SMBHBs presents an interesting problem for gravitational wave data analysis since, due to the LISA response function, the sources have a bi-modal sky solution. We show here that it is possible not only to detect multiple SMBHBs in the data stream, but also to investigate simultaneously all the various modes of the global solution. In all cases, the algorithm returns parameter determinations within $5\sigma$ (as estimated from the Fisher Matrix) of the true answer, for both the actual and antipodal sky solutions.Comment: submitted to Classical & Quantum Gravity. 19 pages, 4 figure

Binary black hole spectroscopy

We study parameter estimation with post-Newtonian (PN) gravitational waveforms for the quasi-circular, adiabatic inspiral of spinning binary compact objects. The performance of amplitude-corrected waveforms is compared with that of the more commonly used restricted waveforms, in Advanced LIGO and EGO. With restricted waveforms, the properties of the source can only be extracted from the phasing. For amplitude-corrected waveforms, the spectrum encodes a wealth of additional information, which leads to dramatic improvements in parameter estimation. At distances of $\sim 100$ Mpc, the full PN waveforms allow for high-accuracy parameter extraction for total mass up to several hundred solar masses, while with the restricted ones the errors are steep functions of mass, and accurate parameter estimation is only possible for relatively light stellar mass binaries. At the low-mass end, the inclusion of amplitude corrections reduces the error on the time of coalescence by an order of magnitude in Advanced LIGO and a factor of 5 in EGO compared to the restricted waveforms; at higher masses these differences are much larger. The individual component masses, which are very poorly determined with restricted waveforms, become measurable with high accuracy if amplitude-corrected waveforms are used, with errors as low as a few percent in Advanced LIGO and a few tenths of a percent in EGO. The usual spin-orbit parameter $\beta$ is also poorly determined with restricted waveforms (except for low-mass systems in EGO), but the full waveforms give errors that are small compared to the largest possible value consistent with the Kerr bound. This suggests a way of finding out if one or both of the component objects violate this bound. We also briefly discuss the effect of amplitude corrections on parameter estimation in Initial LIGO.Comment: 28 pages, many figures. Final version accepted by CQG. More in-depth treatment of component mass errors and detectability of Kerr bound violations; improved presentatio

Heat protective coatings on niobium alloys

Розглянуто різноманітні склади і технології отримання теплозахисних покриттів. Аналіз виявив, що при плазмо-дифузійному нанесенні на поверхні ніобієвого сплаву формувалось багатошарове покриття. Високопористий плазмо-напилений шар силіцидумолібдену має значний розкид по товщині (h=100...350 мкм, H20=6880 МПа). При дослідженні мікроструктури зразків з плазмо-дифузійним покриттям після випробувань виявлено, що тріщини в покритті зароджуються в процесі повзучості здебільшого на границі розділу плазмового і дифузійного шарів покриття. Осередком їх зародження є окремі несуцільності в дифузійному шарі в початковому стані. Поширення тріщин відбувається як в плазмовий, так і в дифузний шари покриття. Гальмування зростання тріщин в плазмовому шарі відбувається за рахунок округлого характеру пор і підвищеної пластичності цього шару. Зростання тріщин в глиб зразка, як правило, гальмується боридним підшаром. Перевага плазмо-дифузійної технології забезпечила підвищену пластичність покриття, наявність тонких бар'єрних підшарів, не суцільну структуру покриття, наявність легкоплавких з'єднань, що сприяють заліковуванню дефектів в покритті, підвищенню його корозійної стійкості і опору термовтомлювальному руйнуванню. Поєднання цих властивостей дозволило забезпечити підвищення довговічності в порівнянні з силіцидними і боросиліцидними покриттями в умовах ізотермічної повзучості на повітрі (1400оС, 50МПа) 1,9...3,7 рази і в умовах термоциклічної повзучості (1400 - 250оС, 50 МПа) в 6,8...8,5 раз. Визначено, що застосування дискретної структури дозволить збільшити товщину шару покриттів та забеспечити підвищення їх робочих властивостей.The article shows that during plasma-diffusion deposition, a multilayer coating was formed on the surface of the niobium alloy. A highly porous plasma-sprayed layer of molybdenum silicide has a significant spread in thickness (h=100...350 m, H20=6880 MPa). When studying the microstructure of samples with a plasma-diffusion coating after testing, it was found that cracks in the coating originate in the process of creep, mostly at the interface between the plasma and diffusion layers of the coating. The source of their origin is individual discontinuities in the diffusion layer as delivered. Crack propagation occurs both into the plasma and diffusion layers of the coating. Crack growth in the plasma layer is inhibited due to the rounded nature of the pores and the increased plasticity of this layer. The growth of cracks deep into the sample is, as a rule, inhibited by a boride sublayer. The advantage of plasma-diffusion technology provided an increased plasticity of the coating, the presence of thin barrier sublayers, a discontinuous coating structure, the presence of low-melting compounds that contribute to the healing of defects in the coating, an increase in its corrosion resistance and resistance to thermal fatigue destruction. The combination of these properties made it possible to provide an increase in durability compared to silicide and borosilicide coatings under conditions of isothermal creep in air (1400 °C, 50 MPa) 1.9...3.7 times and under conditions of thermal cyclic creep (1400-250 °C, 50 MPa) in 6.8...8.5 times. It has been determined that the use of a discrete structure will increase the thickness of the coating layer and ensure an increase in their working properties.Рассмотрены различные составы и технологии получения теплозащитных покрытий. Анализ выявил, что при плазменно-диффузионной нанесении на поверхности ниобиевых сплава формировалось многослойное покрытие. Высокопористый плазменно-напыленный слой силицидамолибдена имеет значительный разброс по толщине (h=100...350 мкм, H20=6880 МПа). При исследовании микроструктуры образцов с плазменно-диффузионным покрытием после испытаний обнаружено, что трещины в покрытии зарождаются в процессе ползучести большей частью на границе раздела плазменного и диффузионного слоев покрытия. Очагом их зарождения являются отдельные несплошности в диффузионном слое в состоянии поставки. Распространение трещин происходит как в плазменный, так и в диффузионный слои покрытия. Торможение роста трещин в плазменном слое происходит за счет округлого характера пор и повышенной пластичности этого слоя. Рост трещин вглубь образца, как правило, тормозится боридным подслоем. Преимущество плазменно-диффузионной технологии обеспечило повышенную пластичность покрытия, наличие тонких барьерных подслоев, не сплошную структуру покрытия, наличие легкоплавких соединений, способствующих залечиванию дефектов в покрытии, повышению его коррозион-ной стойкости и сопротивлению термоусталостному разрушению. Сочетание этих свойств позволило обеспечить повышение долговечности по сравнению с силицидными и боросилицидными покрытиями в условиях изотермической ползучести на воздухе (1400 оС, 50 МПа) 1,9...3,7 раза и в условиях термоциклической ползучести (1400 - 250 оС, 50 МПа) в 6,8...8,5 раз. Определено, что применение дискретной структуры позволит увеличить толщину слоя покрытий и обеспечить повышение их рабочих свойств

Testing Alternative Theories of Gravity using LISA

We investigate the possible bounds which could be placed on alternative theories of gravity using gravitational wave detection from inspiralling compact binaries with the proposed LISA space interferometer. Specifically, we estimate lower bounds on the coupling parameter \omega of scalar-tensor theories of the Brans-Dicke type and on the Compton wavelength of the graviton \lambda_g in hypothetical massive graviton theories. In these theories, modifications of the gravitational radiation damping formulae or of the propagation of the waves translate into a change in the phase evolution of the observed gravitational waveform. We obtain the bounds through the technique of matched filtering, employing the LISA Sensitivity Curve Generator (SCG), available online. For a neutron star inspiralling into a 10^3 M_sun black hole in the Virgo Cluster, in a two-year integration, we find a lower bound \omega > 3 * 10^5. For lower-mass black holes, the bound could be as large as 2 * 10^6. The bound is independent of LISA arm length, but is inversely proportional to the LISA position noise error. Lower bounds on the graviton Compton wavelength ranging from 10^15 km to 5 * 10^16 km can be obtained from one-year observations of massive binary black hole inspirals at cosmological distances (3 Gpc), for masses ranging from 10^4 to 10^7 M_sun. For the highest-mass systems (10^7 M_sun), the bound is proportional to (LISA arm length)^{1/2} and to (LISA acceleration noise)^{-1/2}. For the others, the bound is independent of these parameters because of the dominance of white-dwarf confusion noise in the relevant part of the frequency spectrum. These bounds improve and extend earlier work which used analytic formulae for the noise curves.Comment: 16 pages, 9 figures, submitted to Classical & Quantum Gravit