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A mild and efficient approach for the electrochemical conversion of benzyl alcohols to benzaldehydes is reported in homogeneous medium using Carbon/Stainless Steel electrodes and NaCl as mediator with H2SO4 as supporting electrolyte. To achieve excellent product conversion, optimization of the reaction condition with various parameters was carried out in a beaker type cell. In 2 F of current density and ambient temperature, benzyl alcohols electrochemically oxidized to benzaldehydes in 90% yield. The present work demonstrates a green and sustainable route for benzaldehydes preparation and the superiority of electrochemical method for organic synthesis. [ABSTRACT FROM AUTHOR]

In the present study, the dynamic response of block foundations of different equivalent radius to mass (Ro/m) ratios under coupled vibrations is investigated for various homogeneous and layered systems. The frequency-dependent stiffness and damping of foundation resting on homogeneous soils and rocks are determined using the half-space theory. The dynamic response characteristics of foundation resting on the layered system considering rock–rock combination are evaluated using finite element program with transmitting boundaries. Frequencies versus amplitude responses of block foundation are obtained for both translational and rotational motion. A new methodology is proposed for determination of dynamic response of block foundations resting on soil–rock and weathered rock–rock system in the form of equations and graphs. The variations of dimensionless natural frequency and dimensionless resonant amplitude with shear wave velocity ratio are investigated for different thicknesses of top soil/weathered rock layer. The dynamic behaviors of block foundations are also analyzed for different rock–rock systems by considering sandstone, shale and limestone underlain by basalt. The variations of stiffness, damping and amplitudes of block foundations with frequency are shown in this study for various rock–rock combinations. In the analysis, two resonant peaks are observed at two different frequencies for both translational and rotational motion. It is observed that the dimensionless resonant amplitudes decrease and natural frequencies increase with increase in shear wave velocity ratio. Finally, the parametric study is performed for block foundations with dimensions of 4 m × 3 m × 2 m and 8 m × 5 m × 2 m by using generalized graphs. The variations of natural frequency and peak displacement amplitude are also studied for different top layer thicknesses and eccentric moments.

An optical model of a shock wave generated due to supersonic airflow around a body of an ogival form is developed. Mean values of airflow parameters were calculated from the Navier–Stokes equations using the CFD Fluent 6.0 software package accounting for the gas compressibility. It is shown that the maximum values of the structure parameters are several orders of magnitude larger than the values typical for an unperturbed shock wave in the atmosphere. Results of numerical simulation of propagation of an optical beam which crosses the shock wave at the beginning of a path and then propagates through a homogeneous medium are presented. It is shown that an increase in the aircraft speed increases the transverse dimensions of the beam due to diffraction. The angular deviation of the beam from rectilinear propagation under the impact of the shock wave depends only on the altitude above the Earth's surface where the shock wave is generated. The impact of the shock wave on the crossing beam weakens as the altitude increases. [ABSTRACT FROM AUTHOR]

In article the new class of homogeneous environments called by authors “homogeneous register environments with programmable structure" which basic paradigm is the mathematical apparatus of expanded binary fields of E.Galua of GF (2m) is offered.

We consider the stress-strain state of the circular bearing element-bulkhead, which is used in many technical devices. To describe the dynamic problem of the theory of elasticity adopted the hypothesis of a flat section and incompressible layers. A mathematical model of twisting motion in the plane and twists in the cross sections of the ring. Presents some analytical solutions and graphical dependences.

The effective constitutive parameters of a high-temperature superconducting (HTS) metamaterial are extracted from measured scattering parameters at liquid nitrogen temperature (≈75.68 K at the National Institute of Standards and Technology, Boulder, CO, USA). The YBa2Cu3O7 split-ring resonator (SRR) arrays are placed inside a WR-90 waveguide with two different orientations and are excited with the dominant TE10 mode in both cases. By treating the SRR array as a homogeneous medium described by the biaxial permittivity and permeability diagonal tensors, the two sets of S parameters allow for the extraction of three out of the six tensor components. The extracted parameters are then compared to full-wave simulations of SRR arrays in free space. The samples are measured from 8.2 to 12 GHz and show a frequency band between 9.25 and 10.45 GHz with a negative effective permeability, as expected. Finally, numerous high-quality factor resonances that accompany the main resonances are observed in both the low-temperature measurement and the low-loss simulation. [ABSTRACT FROM PUBLISHER]

Homogeneous graft copolymerization of methyl methacrylate onto cellulose and cellulose acetate was carried out in various solvents and solvent systems taking ceric ammonium nitrate, tin (II) 2-ethyl hexanoate [Sn(Oct)] and benzoyl peroxide as initiators. The effect of solvents, initiators, initiator and monomer concentration, on graft yield, grafting efficiency and total conversion of monomer to polymer were studied. Formation of Ce ion during grafting in presence of CAN enhances the grafting efficiency. Methylene blue was used as a homopolymer inhibitor and controlled the molecular weight of the grafted polymer and its effect on grafting was also studied. In presence of MB, amount of PMMA homopolymer formation reduced and consequently grafting efficiency increased. The number average molecular weights and polydispersity indices of the grafted PMMA were found out by gel permeation chromatography. The products were characterized by FTIR and H-NMR analyses and possible reaction mechanisms were deduced. Finally, thermal degradation of the grafted products was also studied by thermo-gravimetric and differential thermo-gravimetric analyses. [ABSTRACT FROM AUTHOR]

Abstract: Optical response of a novel dye has been studied in various media like neat and mixed binary solvents, aqueous SDS micelles and β-cyclodextrin (β-CD) nanocavities. Fluorescence parameters in pure and mixed binary solvents have been found to be sensitive to the nature of the microenvironment. The emitting state of the dye in protic solvent is different from that in aprotic solvents. In presence of cations (H+, Mg2+), the dye exists in two tautomeric forms at equilibrium in solution. The values of the equilibrium constant (K) and ΔH 0 have been measured. Values of local dielectric constant (ε) and microviscosity (η) at the region of solubilisation of the dye in aqueous SDS micellar media have been found out. The dye has also been found to form complex with β-CD. The equilibrium constant and the energy of maximum fluorescence of the dye encapsulated by β-CD have been determined. [Copyright &y& Elsevier]

This short essay is the first in a series of studies designed to illustrate the Maestro's laborious compositional and scientific activity: The rhetoric of S. Todu ţă's stylistic analyses as reflected in the treaty "Formele muzicale ale barocului în operele lui J. S. Bach" (Baroque Musical Forms in the Works of J. S. Bach); From Urtext to text in Sigismund Todu ţă's opera-oratorio "Manole the Craftsman”; On the footsteps of the composer's hermeneutical annotations to the text of the drama; The aesthetic message of the musical Baroque reflected in the analysis conducted by S. Toduţă on J. S. Bach; Problematization and systematization - complementary dimensions of Todu ţă's musical poetics; Exhortations toward rhetorical research in the light of the treaty "Formele muzicale ale barocului de S. Toduţă" [Baroque Musical Forms by S. Toduţă]; The aesthetic characteristic of the relationship between text and melody in Sigismund Todu ţă's works. The paper dwells on the aesthetic importance of rhetorical generalizations on the value of the aesthetic message, set forth in Sigismund Todu ţă's works. The analyses undertaken reveal that the main means of rhetorical expressions are the triple metaphors between the poetic text, musical discourse and stage movements. The immanence of their homogenous environments is examined along with their transcendence meant to enrich the ideational and emotional content of the work under consideration. The paradigm of the investigations is Sigismund Todu ţă's opera-oratorio Manole the Craftsman, based on the text of Lucian Blaga's drama of the same title. [ABSTRACT FROM AUTHOR]

Abstract: This work is a continuation of Musuuza et al. in which a stability criterion for density-driven flow in a saturated homogeneous medium was derived. The criterion predicted the stability of a system as a function of the density and viscosity contrasts, the magnitude of the flow velocity and the concentration gradients for flow aligned orthogonal to gravity. It could not accurately predict stability transition with increasing velocity, a failure we attributed to dispersion effects that were not included. Small-scale dispersion and molecular diffusion, the main stabilising mechanisms in homogeneous media can stabilise flow if the instability wavelengths are below a certain cutoff. The width of the mixing zone is also central in controlling the range of wavelengths that persist into fingers. We propose a method of quantifying the cutoff wavelength and the width of the mixing zone, which are incorporated into the earlier criterion as constituents of the dispersive part. The earlier criterion is reformulated in terms of the Rayleigh number and with the dispersive part added, we attempt to predict the number of fingers formed which is directly related to the physical stability of the system. The inclusion of the Rayleigh number and dispersion into a single stability criterion provides new insight in the way dispersion affects vertical flow systems. Stability numbers computed with the new criterion are in reasonable agreement with numerical simulations for a range of physical variables. The numerical computations are performed with the software package d 3 f, which uses the cell-centred finite volume and the implicit Euler methods for the spatial and temporal discretisations, respectively. The admission of the density and dispersivities as inputs into the criterion makes it usable in practical problems. [Copyright &y& Elsevier]

The subsurface transport of radioactivity is critically governed by the nature of the medium. In general, the near earth surface medium is a mixture of a homogeneous (sand/soil) part and small stones sitting at few arbitrary locations. A probabilistic approach is adopted to estimate the locations of stones inside a 2D domain and the migration through such a medium for a given distribution is modelled. The entire process is repeated to arrive at a probabilistically averaged concentration value. Results show that the overall transport decreases systematically with the increase of heterogeneity of the medium. Next, simulations are carried out for different heterogeneity and different durations of the migration process. Here also a systematic trend is observed. Concentration corresponding to any in-homogeneity or time of migration falling within this range of modelling can be estimated by interpolation. • Radioactivity migration through a 2D geological medium is modelled. • In that medium, small stones are distributed randomly within sand/soil. • Average migration of radioactivity is estimated probabilistically. • Transport due to different heterogeneity and migration time is calculated. • A method to estimate transport for any inbetween heterogeneity and time is proposed. [ABSTRACT FROM AUTHOR]

Abstract: The possibility of localization of an unknown neutron source in various bulky homogeneous media (box) was studied. For the planar case, two 3He detectors on the opposite faces of the box were used. A constant polypropylene shield around the box and detectors was used to eliminate the varying contribution from the environment to increase count rates of the detectors and to protect the experimentalist. It is shown that the location of a single small neutron emitting source in a large box can be found to a better than 7% by using two neutron detectors positioned on parallel faces of the box, coplanar with the source. The localization requires measurement of the count rate of both the unknown source and an extra source positioned on one of the faces of the box. The localization is based on the finding that the ratio of the count rates of the two detectors is an exponential function of the distance of the source from one of the detectors. [Copyright &y& Elsevier]

This paper addresses the problem of practical crack identification in electrically conducting specimens using only boundary measurements. The method is commonly referred to in the literature as Electrical Impedance Tomography (EIT).Crack identification is determined from the electrical impedance distribution, which amounts to solving an inverse problem, starting from boundary measurements. Whereas this kind of inverse problem has been extensively addressed in its theoretical and numerical aspects, there is a scarcity of experimental results aimed at examining the applicability of the method for real conditions.We present new experimental results, based on a simple identification methodology. The efficiency and limitations of this method are assessed through a series of numerical simulations and laboratory experiments on two-dimensional geometries. Following a preliminary numerical validation stage, actual crack detection is carried out on a discrete network of resistors, as an approximation to Laplace''s equation. Next, experiments are carried out on a continuous conductive medium, containing one and two flaws. Our results show that EIT is a promising candidate for crack identification in real life conditions with a potential for multiple crack detection. [Copyright &y& Elsevier]

We consider the boundary value problem. Here u ∈ ℝ2, D = diag{ d1, d2}, d1, d2 > 0, and the function F is jointly smooth in ( u, μ) and satisfies the following condition: for 0 < μ ≪ 1 the boundary value problem has a homogeneous (independent of x) cycle bifurcating from a loop of the separatrix of a saddle. We establish conditions for stability and instability of this cycle and give a geometric interpretation of these conditions. [ABSTRACT FROM AUTHOR]

This study deals with a methodology for increasing the efficiency of dynamic process calculations in elastic elements of complex engineering constructions. We studied the complex dynamic processes in a simple engineering construction, a mechanical system of an elastic body–continuous flow of homogeneous medium. The developed methodology is based on the use of a priori information on some of the vibrations forms, the construction of a "simplified" mathematical model of system dynamics, and the obtaining of an analytical relationship that describe the overall range of factors on the elastic vibrations of system. The methodology is used for cases of complex vibrations of elastic bodies, and the obtained results can serve as a basis for choosing the main technological and operational parameters of elastic elements of mechanisms and machines that perform complex vibrations. The results obtained in this work are the basis for calculating the blast effect on the elements of protective structures in order to increase their protective capacity by improving the method of their attachment or by using additional reinforcement, buff load effects on the elements of drilling strings and dynamic processes that occur during surface strengthening by work hardening in order to avoid resonance phenomena, and technological processes of vibration displacement or vibration separation of granular media. [ABSTRACT FROM AUTHOR]

An edge-coupled quarter wavelength resonator and half-wavelength open stubs are used for designing a highly selective wideband bandpass filter (BPF). A homogeneous medium is considered and the even-odd mode approach is used for filter analysis. Next, a microstrip line implementation procedure is described. The filter has sharp rejection, wide stopband, low insertion loss (IL), and fabrication simplicity. A prototype BPF having 69.5% 3-dB fractional bandwidth (FBW) is fabricated. A simple stub modification extends the upper 20-dB stopband to five times that of the filter upper cutoff frequency. Passband IL is within 1.6dB [ABSTRACT FROM PUBLISHER]

In this paper, a full wave partial element equivalent circuit (PEEC) technique using exact Green's function is introduced for the parameter extraction of a passive device in a homogeneous media over a wide frequency range from de to a frequency of interest. This technique makes use of some analytical techniques and cartesian multipole expansion to derive simple closed form expressions for each individual element of the coupling matrices that commonly arise in integral equation algorithms, in terms of the wave number alone. Hence, these matrices can be reused each time a new frequency is selected. As simple closed form expressions are used, very fast computation is possible [ABSTRACT FROM PUBLISHER]