Equation level matching: An extension of the method of matched asymptotic expansion for problems of wave propagation

We introduce an alternative to the method of matched asymptotic expansions. In the "traditional" implementation, approximate solutions, valid in different (but overlapping) regions are matched by using "intermediate" variables. Here we propose to match at the level of the equations involved, via a "uniform expansion" whose equations enfold those of the approximations to be matched. This has the advantage that one does not need to explicitly solve the asymptotic equations to do the matching, which can be quite impossible for some problems. In addition, it allows matching to proceed in certain wave situations where the traditional approach fails because the time behaviors differ (e.g., one of the expansions does not include dissipation). On the other hand, this approach does not provide the fairly explicit approximations resulting from standard matching. In fact, this is not even its aim, which to produce the "simplest" set of equations that capture the behavior

Simulation of epoxicomposites structures optical characteristics with operator transformations parameters

Розглянуто науково-практичну проблему створення композитних матеріалів і покриттів на їх основі з підвищеними експлуатаційними характеристиками шляхом дослідження структур зон міжфазної взаємодії в процесі тверднення епоксикомпозитів. Встановлено закономірності кінетики формування зовнішніх поверхневих шарів як прояву таких зон залежно від умісту, дисперсності й фізико-хімічної природи введеного у зв’язувач наповнювача та видано рекомендації щодо прогнозованого регулювання властивостями cформованих матеріалів. Обгрутовано вплив структурних характеристик і геометричних параметрів зовнішніх поверхневих шарів у матриці навколо частинок наповнювача на фізико-механічні характеристики композитного матеріалу.The theoretical and practical problem of composite materials and coatings creating with improved performance by studying the band structure of the interphase interactions during the curing epoxycomposites was considered. There were established the regularities of formation cinetics of the outer surface layers, as a manifestation of such zones. They depend on the content, dispersion and physico- chemical nature of the introduction in the filler and the type of recommendations for management of the predicted properties of generated materials. There was investigated and substantiated the influence of structural characteristics and geometric parameters of the outer surface layers of the matrix around the filler particles and fibers on the dynamics of physical and mechanical char-acteristics of cross-linking of the composite material. A mathematical model of resource in the process of curing epoxycomposites based was builed on the methodology defined boundaries and visualization of spatial clusters of external potentials of the surface layers of dispersed filler. It made the possibility to assess the characteristics of the main stages of the dynamics around dispersed particles microstructures in the volume of the filler matrix composite. It has been hypothesized about the decisive influence of the areas geometric parameters of interfacial interaction on changes in physical and mechanical properties of the filled epoxy composites was . This approach is based on well-developed views, including academician Lipatov Y. S., influence of the solid surface on the kinetics of the formation, morphology, intra - and intermolecular bonds, on the topology of the nets, etc. and, in the end, on the final properties of the polymer matrix. The results of these studies will be used in the development of technology of formation materials and coatings based on them

Simulation of epoxicomposites structures optical characteristics with operator transformations parameters

Розглянуто науково-практичну проблему створення композитних матеріалів і покриттів на їх основі з підвищеними експлуатаційними характеристиками шляхом дослідження структур зон міжфазної взаємодії в процесі тверднення епоксикомпозитів. Встановлено закономірності кінетики формування зовнішніх поверхневих шарів як прояву таких зон залежно від умісту, дисперсності й фізико-хімічної природи введеного у зв’язувач наповнювача та видано рекомендації щодо прогнозованого регулювання властивостями cформованих матеріалів. Обгрутовано вплив структурних характеристик і геометричних параметрів зовнішніх поверхневих шарів у матриці навколо частинок наповнювача на фізико-механічні характеристики композитного матеріалу.The theoretical and practical problem of composite materials and coatings creating with improved performance by studying the band structure of the interphase interactions during the curing epoxycomposites was considered. There were established the regularities of formation cinetics of the outer surface layers, as a manifestation of such zones. They depend on the content, dispersion and physico- chemical nature of the introduction in the filler and the type of recommendations for management of the predicted properties of generated materials. There was investigated and substantiated the influence of structural characteristics and geometric parameters of the outer surface layers of the matrix around the filler particles and fibers on the dynamics of physical and mechanical char-acteristics of cross-linking of the composite material. A mathematical model of resource in the process of curing epoxycomposites based was builed on the methodology defined boundaries and visualization of spatial clusters of external potentials of the surface layers of dispersed filler. It made the possibility to assess the characteristics of the main stages of the dynamics around dispersed particles microstructures in the volume of the filler matrix composite. It has been hypothesized about the decisive influence of the areas geometric parameters of interfacial interaction on changes in physical and mechanical properties of the filled epoxy composites was . This approach is based on well-developed views, including academician Lipatov Y. S., influence of the solid surface on the kinetics of the formation, morphology, intra - and intermolecular bonds, on the topology of the nets, etc. and, in the end, on the final properties of the polymer matrix. The results of these studies will be used in the development of technology of formation materials and coatings based on them

Simple Viscous Flows: from Boundary Layers to the Renormalization Group

The seemingly simple problem of determining the drag on a body moving through a very viscous fluid has, for over 150 years, been a source of theoretical confusion, mathematical paradoxes, and experimental artifacts, primarily arising from the complex boundary layer structure of the flow near the body and at infinity. We review the extensive experimental and theoretical literature on this problem, with special emphasis on the logical relationship between different approaches. The survey begins with the developments of matched asymptotic expansions, and concludes with a discussion of perturbative renormalization group techniques, adapted from quantum field theory to differential equations. The renormalization group calculations lead to a new prediction for the drag coefficient, one which can both reproduce and surpass the results of matched asymptotics

Application of harmonic wavelets to processing oscillating hydroacoustic signals

The paper is devoted to the application of specific functions called harmonic wavelets, which are aimed at processing a wide range of oscillating hydroacoustic signals including multiharmonic and transient signals. We provide basics of the harmonic wavelet transform and a two-stage algorithm for computing wavelet coefficients based on the discrete Fourier transform. We introduce a special efficiency factor of applying these wavelets to oscillating hydroacoustic signals. Application of harmonic wavelets is efficient for processing oscillating hydroacoustic signals since harmonic wavelets have similarities with these types of signals. In many cases the best basis is the basis that has high correlation with the investigated signals since signal representation in such a basis will require a small number of components. We devote special attention to a very important practical task - denoising of oscillating signals using special statistical criteria and wavelet-based thresholding

A Case Study Exploring Side-Channel Attacks On Pet Wearables

IoT has long since come to the pet industry resulting in a proliferation of data-intensive devices including tracking anything from activity, health, to location. The resulting ‘Internet of Pets’ is generating large volumes of animal data which, due to the close link between the digital profile of companion animals held as pets (e.g., cats and dogs) and their caregivers holds significant security and privacy implications. In this case study we explore the vulnerability of such pet wearables to side-channel attacks, describing our implementation of an electromagnetic attack on a now discontinued dog activity tracker. We show how we were able to successfully exfiltrate data from the device during the Base64 encoding process and discuss what implications this holds for the security of these devices, given the lack of protection that animal data is afforded under extant existing data protection policy and legislation

The Introduction of DTT in Latin America: Politics and Policies

The switch to digital terrestrial television is now a global trend. In Latin America, where the terrestrial platform has a dominant role, the introduction of DTT raises important questions for economic and industrial development, as well as pluralism. This article focuses on the earliest experiences (Brazil, México and Argentina) and those of the newcomers (Chile, Colombia and Uruguay). The aim is to outline the differences between the various political decision processes and the way with which they have been turned into communication policies, so as to draw some conclusions that contribute to visualizing the future of television in the region.Publicad

Предсказание активности низкомолекулярных ингибиторов активации классического пути комплемента методом компьютерного скрининга

Using the molecular docking we estimated the free energy of binding of low-molecular ligands with the first component of complement protein C1q. The theoretically predicted values of IC50 allow selecting ligands with the highest inhibitory potential for further in vitro experimentsС помощью молекулярного докинга оценена свободная энергия связывания низкомолекулярных лигандов с белком первого компонента комплемента C1q in silico. Теоретически рассчитанная константа IC50 позволяет отобрать наиболее перспективные ингибиторы активации комплемента. помощью молекулярного докинга оценена свободная энергия связывания низкомолекулярных лигандов с белком первого компонента комплемента C1q in silico. Теоретически рассчитанная константа IC50 позволяет отобрать наиболее перспективные ингибиторы активации комплемента