Narrow Results

This research focuses on studying the influence of the Hall current on the propagation and reflection of elastic waves in a non-local isotropic rotating solid. The dispersion relation is derived to determine the speed of propagation, revealing the presence of three coupled quasi-waves within the solid: coupled qP-wave, qT-wave and qSV-wave. The rotational motion and the Hall current introduce anisotropic characteristics to the medium, leading to the emergence of quasi-type waves. The rotation disrupts the isotropic nature of the solid, transforming it into an anisotropic medium. Consequently, the purely longitudinal and transverse waves are converted into quasi-longitudinal and quasi-transverse waves. The speed of the propagating waves is dependent on specific elastic parameters. By employing free boundary conditions, the mathematical calculation and graphical representation of wave amplitude ratios are determined. The influence of rotational frequency, non-locality, fractional order and Hall current parameters on the computed results is investigated. The conservation of energy validates the accuracy of the obtained results. Furthermore, it is observed that the previously reported results in the literature can be obtained as a special case when rotation and the Hall current are absent.

The propagation and reflection of thermo-elastic waves through diffusive nonlocal isotropic medium had been studied in this paper. The Green–Lindsay model of thermo-elasticity is incorporated in the context of Temperature Rate Dependent Theory. Using Helmholtz vector decomposition rule, the system of governing equations has been transformed to their respective components. The dispersion relation in frequency indicates the existence of three coupled waves and one independent wave propagating through the medium. The coupled waves are affected by non-locality, temperature field and diffusivity in the medium; anyhow, un-coupled shear vertical wave is only affected by the non-local parameter. The reflection of $P$-wave is also studied at the free boundary of the solid and their corresponding amplitude ratios are computed using set of suitable boundary conditions. The obtained results are further discussed graphically for significant physical parameters of interest. The results in the literature are obtained as a special case after ignoring the diffusivity in the solid.

This paper studies an extension of inductive definitions in the context of a type-free theory. It is a kind of simultaneous inductive definition of two predicates where the defining formulas are monotone with respect to the first predicate, but not monotone with respect to the second predicate. We call this inductive definition half-monotone in analogy of Allen’s term half-positive.

We can regard this definition as a variant of monotone inductive definitions by introducing a refined order between tuples of predicates. We give a general theory for half-monotone inductive definitions in a type-free first-order logic. We then give a realizability interpretation to our theory, and prove its soundness by extending Tatsuta’s technique. The mechanism of half-monotone inductive definitions is shown to be useful in interpreting many theories, including the Logical Theory of Constructions, and Martin-Löf’s Type Theory. We can also formalize the provability relation “a term p is a proof of a proposition P” naturally. As an application of this formalization, several techniques of program/proof-improvement can be formalized in our theory, and we can make use of this fact to develop programs in the paradigm of Constructive Programming. A characteristic point of our approach is that we can extract an optimization program since our theory enjoys the program extraction theorem.

We demonstrate a large area time domain terahertz (THz) imaging system capable of scanning 1 meter square area in less than 20-100 minutes for several security applications. The detection of concealed explosives; metallic and non-metallic weapons (such as ceramic, plastic or composite guns and knives); and flammables in luggage, packages and personnel has been demonstrated. Transmission mode images of luggage containing threat items are discussed. Reflection mode images of luggage and personnel are discussed. Time domain THz images can be analyzed for 3 dimensional and volumetric information. Time domain THz images have advantages over coherent narrow band imaging methods, with freedom from interference artifacts and with greater ability to discard irrelevant or intervening reflections through time discrimination.

In this paper, we use the reflection (or parity) operator to construct the new algebra whose maximum occupation number is finite. For the Hamiltonian proportional to the number operator, we discuss the thermostatistics and compute the thermodynamical quantities such as distribution function, multiparticle distribution function, mean energy and specific heat. We also calculate the intercept for this algebra to show that a particle obeying this algebra is an exotic particle which is neither a boson nor a fermion.

The Nariai black hole, whose two horizons are lying close to each other, is an extreme and important case in the research of black hole. In this paper we study the evolution of a massless scalar field scattered around in 5D Schwarzschild–de Sitter black string space. Using the method shown by Brevik and Simonsen (2001) we solve the scalar field equation as a boundary value problem, where real boundary condition is employed. Then with convenient replacement of the 5D continuous potential by square barrier, the reflection and transmission coefficients (R, T) are obtained. At last, we also compare the coefficients with the usual 4D counterpart.

Ballistic electron transport through a finite chain of quantum circular rings is studied in the presence of the Rashba coupling, of strength α, and of a perpendicular magnetic field B. The transmission and reflection coefficients for a single ring, obtained analytically, help obtain the conductance through a chain of rings as a function of the strength α, the field B, and of the wave vector k of the incident electron. Due to destructive spin interferences caused by the Rashba coupling the chain can be totally opaque for certain ranges of k the width of which depends on values of α and B. Outside these ranges the conductance oscillates with high values between e²/h and 2e²/h. The effect of a periodic modulation of α or B on the conductance gaps is investigated. A periodic, square-wave conductance pattern, pertinent to the development of the spin transistor, results within wide stripes in the parameter space spanned by k, α, and B. Finite temperatures smoothen the square-wave profile of the conductance but do not alter its periodic character.

In this paper, we systemically and numerically investigate the effects of three types of Nanoparticles on the efficiency of solar cells. Finite Difference Time Domain method has been implemented to compute the absorption spectra in such proposed solar cell structure. High efficiency has been achieved by optimizing the nanoparticles layer by tuning the fraction of nanoparticles on the host layer.

We investigate transmission and reflection properties of a broadband pulse with normal incidence on silicon-metal-silicon (SMS) for the first time, to the best of our knowledge. The results show that in lower frequency range, the transmission is close to zero, and the reflection and loss are in the range 0.50–0.90, 0.10 to 0.50, respectively. In higher frequency range, the transmission spectrum has two peaks, with transmittance 0.69, 0.90, and at same frequencies as the transmission peaks, the reflection spectrum has two troughs with reflectance 0.00, 0.02 and corresponding losses are 0.10, 0.29, respectively. This simple waveguide structure may have potential applications in silicon photonics, such as filters and laser oscillation cavities.

In this paper, we explore the application of nonlocal theory to analyze the phenomenon of coupled thermoelastic wave reflection in a semiconducting diffusive medium, considering its temperature rate dependence. The governing equations are deconstructed using the Helmholtz vector rule, allowing us to delve into the behavior of the system. By calculating the dispersion relation in terms of propagation speed, we investigate four coupled longitudinal waves alongside an independent nondispersive transverse wave within the local medium. The cut-off frequencies for each wave are discussed, shedding light on their characteristics. Furthermore, we delve into the phenomenon of coupled longitudinal displacement waves at the medium’s boundary. Analytical derivations of amplitude ratios are presented, accompanied by graphical representations of their behavior, focusing on a semiconductor material such as copper. We examine the effects of physical parameters, including the nonlocal and diffusive parameters, on the obtained results. It is important to note that the existing literature primarily lacks consideration of diffusivity and plasma transportation. Lastly, we validate our findings by investigating the conservation of energy within the system.

Oblique light propagation through a chiral photonic crystal (PC) layer with gradient parameters of modulation is considered. The problem is solved by Ambartsumian's layer addition modified method. It is shown that suppressing of diffraction oscillations near the photonic band gap (PBG) is possible at certain conditions. Thus, at certain conditions, the spectra for the finite PC layer is the same as that for the half space.

We propose a reflective acoustic metasurface by taking advantage of the synergetic coupling of two kinds of widely used elements, the resonant cavity and the labyrinthine beam. A full 2$\pi$ phase shift range can be obtained by varying the neck width. The structure manipulates the reflective waves on a very deep subwavelength scale with the thickness being only 1/50 of the wavelength, which eliminates the enormous obstacle in low frequency applications. The synergetic coupling of the resonant cavity and the inner labyrinthine beams provide a useful guide for the design of acoustic metasurfaces.

We report a graphene-based tunable ultra-narrowband mid-infrared filter which can be tuned from 4.45122 $\mu$m to 4.44675 $\mu$m by tuning the Fermi level from 0.2 eV to 0.6 eV. Furthermore, the reflection bandwidth is less than 0.2 nm and the reflection rate is more than 0.55. The ultra-narrowband filter is designed based on the guided-mode resonance (GMR) effect. The shift of reflection peak is mainly caused by the change of the real part of the graphene’s permittivity. This tunable ultra-narrowband mid-infrared filter can be applied in the mid-infrared microscopy.

In this paper, photovoltaics (PV)- or solar cells based on two types of nanoparticles have been investigated. The suggested four-layer solar cell model consists of metallic nanoparticle (Ag–Au) layers that are Si-based and covered by SiN. The transmission and reflection of the incident light on the structure model have been computed for different physical parameters of the structure. Higher transmission and lower reflections have been obtained leading to higher efficiency of the solar cells. The matrix model is used, and the numerical results obtained by MAPLE Software Program. The obtained results confirm that the nanoparticle solar cell structure can effectively enhance the efficiency of such structure model.

A complete and fully developed theory of all optical phenomena (refraction, reflection, absorption, and transparency) and the corresponding optical properties of ultrathin crystalline films (optical indices) are presented in this paper, especially along the direction in which the structure is spatially limited (perpendicular to surfaces). While these indices depend on the position of the crystallographic plane (where the mentioned optical phenomena occur) with respect to the two interfaces, these values can be measured/ determined in experiments only for the film as a whole. For these reasons, it is important to answer the question of how to define these optical indices precisely.

Accurate iris segmentation is presented in this paper, which is composed of two parts, reflection detection and eyelash detection. Eyelashes are classified into two categories, separable and multiple. An edge detector is applied to detect separable eyelashes, and intensity variances are used to recognize multiple eyelashes. Reflection is also divided into two types, strong and weak. A threshold and statistical model is proposed to recognize the strong and weak reflection, respectively. We have developed an iris recognition approach for testing the effectiveness of the proposed segmentation method. The results show that the proposed method can reduce recognition error for the iris recognition approach.

Learning from examples has a number of distinct algebraic forms, depending on what is to be learned from the available information. One of these forms is , where the input-output tuple (x, y) is the available information, and G represents the process determining the mapping from x to y. Various models, y = f(x), of G can be constructed using the information from the (x, y) tuples. In general, and for real-world problems, it is not reasonable to expect the exact representation of G to be found (i.e. a formula that is correct for all possible (x, y)). The modeling procedure involves finding a satisfactory set of basis functions, their combination, a coding for (x, y) and then to adjust all free parameters in an approximation process, to construct a final model. The approximation process can bring the accuracy of the model to a certain level, after which it becomes increasingly expensive to improve further. Further improvement may be gained through constructing a number of agents {α}, each of which develops its own model f_α. These may then be combined in a second modeling phase to synthesize a team model. If each agent has the ability for internal reflection the combination in a team framework becomes more profitable. We describe reflection and the generation of a confidence function: the agent's estimate of the correctness of each of its predictions. The presence of reflective information is shown to increase significantly the performance of a team.

We study the propagation of nonlinear waves in a three-component reaction–diffusion system. The problem of the existence of the stationary pulse-like solutions is reduced to the analysis of homoclinic trajectories of a fourth-order system of nonlinear ODEs. We have obtained the parameter set corresponding to the homoclinic bifurcations that defines the velocity spectra of the traveling pulses. We have shown that the pulses behave like autowaves annihilating in head-on collision and like dissipative solitons crossing each other, reflecting at boundaries. We have provided a qualitative explanation for such a behavior.

We define adaptability as the capacity of software in adjusting its behavior in response to changing conditions. To list just a few examples, adaptability is important in pervasive computing, where software in mobile devices need to adapt to dynamic changes in wireless networks; autonomic computing, where software in critical systems are required to be self-manageable; and grid computing, where software for long running scientific applications need to be resilient to hardware crashes and network outages. In this paper, we provide a realization of the transparent shaping programming model, called TRAP.NET, which enables transparent adaptation in existing .NET applications as a response to the changes in the application requirements and/or to the changes in their execution environment. Using TRAP.NET, we can adapt an application dynamically, at run time, or statically, at load time, without the need to manually modify the application original functionality-hence transparent.

Recently, object-oriented specifications of distributed systems has gained more attention. The object-oriented approach is known for its flexibility for system construction. However, one of the major challenges is to provide facilities for the dynamic modifications of such specifications during the development and maintenance process. Yet, current work has not addressed the dynamic modifications of specifications of distributed systems. In this paper, we are concerned with formal description techniques that allow for the development and dynamic modification of executable specifications. A two-level model for the evolution of large object-oriented specifications is introduced. The first deals with the dynamic modifications of types (classes), while the second deals with modifications of modules. We have defined a set of structural and behavioral constraints to ensure specification consistency after modification at both levels. To allow dynamic modification of types and modules, we have developed a reflective object-oriented specification language which uses meta-objects to support the modification operations. In this language, types and modules are objects.