Fatigue Life of Reinforced Concrete Integral Bridge

Integral bridges with long spans are becoming popular day by day, as they are easy to construct with long spans and require fewer maintenance efforts due to the absence of bearings. However, due to movement restraints, fatigue stresses build-up that leads to a reduction in a useful life. In this paper results of an analytical study are presented for the fatigue life of an integral bridge exposed to transient loads. Transient analysis of reinforced concrete integral bridge of total length 156 m having 5 continuous spans with the central maximum span of 40 m has been done using ANSYS. The roles of deformation and strain that occur in the bridge have been found to influence fatigue life. Further, midpoint deflection in the longest span, its variation with loading history and its influence on fatigue life has also been analyzed and found to match satisfactorily with standard results.

Об электронной эмиссии из фокальной области симметрично сходящейся поверхностной плазмонной волны на свободной поверхности металлической пленки

Based on the theory of reflection of a plane electromagnetic wave from a plane-layered structure, the excitation and focusing of a radially converging surface plasmon wave on the free surface of a gold film in the Kretschmann scheme are considered. The distribution of the electric field in the vicinity of the focus on the free surface of the film is quantitatively studied. Based on this distribution and the theory of thermofield electron emission from a metal, the time averaged current of electron emission is estimated depending on the amplitude of the normal component of the electric field of the wave at the center of the focal distribution. It was shown that the main part of the emission current comes from a region around the focus center with a diameter of the order of a tenth of the working wavelength in vacuum, and a negligible part of the emission current comes from surrounding the central maximum of the diffraction rings.

Optical-trapping of a red Bessel beam controlled by co-propagating green Gaussian beam in azobenzene liquid crystal

Simultaneous co-propagation of red nondiffracting Bessel beam and green Gaussian beam at milliwatt powers in a photosensitive azobenzene liquid crystal has been studied. The fine displacement of the narrow-width Gaussian beam relative to the Bessel beam central maximum showed the Bessel beam distortion and controlled bending of its core in the direction opposite to the location of green Gaussian beam. After switching off the green beam, the dynamics of restoration of Bessel beam demonstrated the pronounced optical-trapping feature of its central core and transient soliton-like propagation with reduced diameter and increased intensity and propagation depth thus forming a waveguiding channel.

Quantum Rainbows in Positron Transmission through Carbon Nanotubes

Here we report the results of the theoretical investigation of the transmission of channeled positrons through various short chiral single walled carbon nanotubes (SWCNT). The main question answered by this study is “What are the manifestations of the rainbow effect in the channeling of quantum particles that happens during the channeling of classical particles?” To answer this question, the corresponding classical and quantum problems were solved in parallel, critically examined, and compared with each other. Positron energies were taken to be 1 MeV when the quantum approach was necessary. The continuum positron-nanotube potential was constructed from the thermally averaged Molière’s positron-carbon potential. In the classical approach, a positron beam is considered as an ensemble of noninteracting particles. In the quantum approach, it is considered as an ensemble of noninteracting wave packages. Distributions of transmitted positrons were constructed from the numerical solutions of Newton’s equation and the time-dependent Schrödinger equation. For the transmission of 1-MeV positrons through 200-nm long SWCNT (14; 4), in addition to the central maximum, the quantum angular distribution has a prominent peak pair (close to the classical rainbows) and two smaller peaks pairs. We have shown that even though the semiclassical approximation is not strictly applicable it is useful for explanation of the observed behavior. In vicinity of the most prominent peak, i.e., the primary rainbow peak, rays interfere constructively. On one of its sides, rays become complex, which explains the exponential decay of the probability density in that region. On the other side, the ray interference alternates between constructive and destructive, thus generating two observed supernumerary rainbow peaks. The developed model was then applied for the explanation of the angular distributions of 1-MeV positrons transmitting through 200 nm long (7, 3), (8, 5), (9, 7), (14, 4), (16, 5) and (17, 7) SWCNTs. It has been shown that this explains most but not all rainbow patterns. Therefore, a new method for the identification and classification of quantum rainbows was developed relying only on the morphological properties of the positron wave function amplitude and the phase function families. This led to a detailed explanation of the way the quantum rainbows are generated. All wave packets wrinkle due to their internal focusing in a mutually coordinated way and are concentrated near the position of the corresponding classical rainbow. This explanation is general and applicable to the investigations of quantum effects occurring in various other atomic collision processes.

Diffraction Control Methods of Extended Products’ Diameter

In this paper the measurement methods for extended objects’ geometry on the basis of effect of light diffraction which can be applied to technological control of products with wide range of diameters from the smallest to the largest are described. During measurement the method that allows to minimize the influence of disturbing factors on the results of measurements of diameter of thin fibers of small diameters of micron is described. Disturbing factors include excessive flare of area of the central maximum range. The diffraction method is considered that allows to increase to units of micrometers the resolution of the optical measuring converters used in devices to perform technological control of cylindrical extended products of a large diameter such as: cables, wires, cords, etc. The transformation function allowing to calculate diameter of cylindrical products irrespective of their location in a control zone on the basis of the diffraction method of delimitation of the product shadow in optical two-coordinate converters with the dispersing laser bunch is offered and experimentally confirmed. The achieved results can be used for development of high-precision optical devices of technological control of outer diameter and eccentricity of products for cable, pipe and other products in different industry fields.

Mismatch and Conflict: Neurophysiological and Behavioral Evidence for Conflict Priming

Conflict-related cognitive processes are critical for adapting to sudden environmental changes that confront the individual with inconsistent or ambiguous information. Thus, these processes play a crucial role to cope with daily life. Generally, conflicts tend to accumulate especially in complex and threatening situations. Therefore, the question arises how conflict-related cognitive processes are modulated by the close succession of conflicts. In the present study, we investigated the effect of interactions between different types of conflict on performance as well as on electrophysiological parameters. A task-irrelevant auditory stimulus and a task-relevant visual stimulus were presented successively. The auditory stimulus consisted of a standard or deviant tone, followed by a congruent or incongruent Stroop stimulus. After standard prestimuli, performance deteriorated for incongruent compared to congruent Stroop stimuli, which were accompanied by a widespread negativity for incongruent versus congruent stimuli in the event-related potentials (ERPs). However, after deviant prestimuli, performance was better for incongruent than for congruent Stroop stimuli and an additional early negativity in the ERP emerged with a fronto-central maximum. Our data show that deviant auditory prestimuli facilitate specifically the processing of stimulus-related conflict, providing evidence for a conflict-priming effect.

Imaging with the Photon Scanning-Tunneling Microscope

The use of traditional optics in microscopy has a well-known resolution barrier first presented by Lord Rayleigh. This is the "Rayleigh diffraction limit." In the usual textbook example, the overlapping diffraction rings from two small objects are set so that the central maximum of one pattern falls on the first minimum of the second, The barrier limits the resolution of conventional microscopes to a significant fraction of the wavelength of light.In the past decade two methods were discovered for surpassing the Rayleigh diffraction barrier. The first was actually an independent rediscovery by D. Pohl er al. of a concept originally proposed by Synge (in a 1928 paper reviewed by Albert Einstein),

Space Densities for Powerful Radio Sources in the Light of Unification

As radio survey frequency is raised the proportion of flat-spectrum sources increases in bright flux-limited samples (eg Wall 1994, Aust J Phys47, 625). Differential source counts show a corresponding broadening of the central maximum due to the increasing proportion of flat-spectrum sources. Orr & Browne (1982, MNRAS200, 1067) modelled this change in shape of the source count by proposing a unifying scheme which states that the core-dominated, flat-spectrum radio sources are the steep-spectrum sources with their cores Doppler-boosted due to the alignment of the jets with the line of sight.