基于不规则U型结构的高灵敏度太赫兹微流传感器

设计了一种基于不规则U型结构的高灵敏度太赫兹微流传感器,通过仿真软件研究了传感器金属结构中金属线的长度、宽度与夹角对品质因数与吸收率的影响,以及微流通道高度与盖层厚度对传感器性能的影响,最后仿真计算了传感器对不同质量分数葡萄糖溶液的检测性能.结果 表明:传感器的最佳结构参数为L1=84 μm、L2=82μm、L3 =5...     

Irregular dielectric or permeable bodies in an external field

An integral equation is derived for the electrostatic potential ψ that arises when a uniform dielectric body of arbitrary shape is placed in an applied electrostatic field. By expansion of ψ in a certain basic set, the integral equation becomes a set of linear equations for the expansion coefficients, and it is often practical to solve the set by truncation. As a test, the equations are applied to the problem of a spheroid in a uniform field, and they easily yield the standard results that are usually derived by introducing spheroidal harmonics. Either the integral equation or the equivalent linear equations can be solved in an iterative approximation (the analog of the Born approximation) when the dielectric constant of the body is not too far from unity. For bodies that differ from spherical or cylindrical ones by a small parameter λ, perturbation formulae are derived that solve the equations in powers of λ. The problem of a homogeneous permeable body of arbitrary shape in an external magnetostatic field is reducible to the dielectric problem, but in addition an alternate integral equation for the magnetic problem is discussed.     

Transport of a Passive Tracer by an Irregular Velocity Field

The trajectories of a passive tracer in a turbulent flow satisfy the ordinary differential equation x′(t)=V(t,x(t)), where V(t,x) is a stationary random field, the so-called Eulerian velocity. It is a nontrivial question to define the dynamics of the tracer in the case when the realizations of the Eulerian field are only spatially Hölder regular because the ordinary differential equation in question lacks then uniqueness. The most obvious approach is to regularize the dynamics, either by smoothing the velocity field (the so-called ε-regularization), or by adding a small molecular diffusivity (the so-called κ-regularization) and then pass to the appropriate limit with the respective regularization parameter. The first procedure corresponds to the Prandtl number Pr=∞, while the second to Pr=0. In the present paper we consider a two parameter family of Gaussian, Markovian time correlated fields V(t,x), with the power-law spectrum. Using the infinite dimensional stochastic calculus we show the existence and uniqueness of the law of the trajectory process corresponding to a given field V(t,x) for a certain regime of parameters characterizing the spectrum of the field. Additionally, this law is the limit, in the sense of the weak convergence of measures, of the laws obtained as a result of any of the described regularizations. The so-called Kolmogorov point, that corresponds to the parameters characterizing the relaxation time and energy spectrum of a turbulent, three dimensional flow, belongs to the boundary of the parameter regime considered in the paper.     

An Efficient Model for Layer-by-Layer Analysis of Sandwich Irregular Cylindrical Shells of Revolution

Based on the approach of layer-by-layer analysis, we consider an algorithm for constructing finiteelement models of layers for a refined calculation of the stress-strain state of sandwich cylindrical shells with the application of efficient approximations that increase the rate of convergence of the numerical results and, consequently, allow the order of the systems of equations to be reduced, which is particularly topical in the layer-bylayer analysis of laminated inhomogeneous constructions. An example of applying the models considered to calculate the stress-strain state of a sandwich cylindrical shell with through and non-through cuts is given.     

On the Gradient-Current Mechanism of Formation of the Irregular Structure of the High-Latitude Upper Ionosphere

We consider the gradient-current instability of an inhomogeneous magnetoactive plasma in the approximation of double-fluid magnetohydrodynamics. Unlike the known gradient-drift and current-convective instabilities, the gradient-current instability is related to generation of nonpotential quasistatic electric fields polarized orthogonal to the external magnetic field B ₀ and excited by eddy currents whose density vector lies in the plane passing through the vectors of the magnetic field B ₀ and large-scale electron-density gradient. It is shown that in the high-latitude upper ionosphere, in the regions containing large-scale currents flowing in and out of the ionosphere along the magnetic field, the gradient-current instability can lead to the appearance of sheet-like irregularities extended predominantly in the plane passing through the geomagnetic-field and regular plasma-drift velocity vectors. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 7, pp. 574–587, August 2005.     

Consecutive Parametric Interactions of Light Waves with Nonmultiple Frequencies in Crystals with Irregular Poled Structure

A stochastic theory of quasi-phase-matched consecutive processes, which takes into account peculiarities of the method of creating a nonlinear lattice in crystals, is developed. The influence of aperiodicity of a certain type on the efficiency of the process of consecutive parametric interaction of light waves with nonmultiple frequencies in crystals with irregular poled structure is studied. It has been established that in aperiodically poled nonlinear crystals the regime of exponentially changing intensity of interacting waves can be implemented. A particular case of nondegenerate parametric amplification is also discussed.     

Relevance of the Slip Condition for Fluid Flows Near an Irregular Boundary

We consider the Navier-Stokes equation in a domain with a rough boundary. The roughness is modeled by a small amplitude and small wavelength oscillation, with typical scale e << 1{\varepsilon \ll 1}. For periodic oscillation, it is well-known that the best homogenized (that is regular in e{\varepsilon}) boundary condition is of Navier type. Such result still holds for random stationary irregularities, as shown recently by the first author [5, 15]. We study here arbitrary irregularity patterns.     

Irregular frequency chirp in radiation of an injection laser in high-velocity code modulation

The effect of the shape of the excitation pulses on the magnitude of the frequency chirp in an injection laser is investigated. It is established that as the degree of rectangularity of the pulses becomes higher, the frequency chirp increases. Simultaneous consideration of the effect of residual charge in the active region of the laser, the delay of stimulated radiation, and the frequency chirp indicates that in the case of high-velocity code modulation of an injection laser, in the latter an irregular frequency chirp appears that can exert a noticeable influence on the distortion of code trains of pulses having a super-Gaussian shape, when they propagate in media with a dispersion of 100 p.s./nm/km and above. Belarusian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 45–49, January–February, 1997.     

Inhomogeneous Site Percolation on an Irregular Bethe Lattice with Random Site Distribution

In this paper, we study inhomogeneous site percolation on an irregular Bethe lattice, for considering that percolation often occurs on irregular grids or lattices with variable site neighbours in real-world problems. The explicit expression for cluster-size distribution of this percolation is derived based on probability theory. Moreover, the exact formulas for critical occupation probability, mean cluster size, and percolation probability are obtained using generating function method and generalised recursive approach. In addition, sensitivity analysis and numerical simulation are given to deepen and illustrate the results.     

Studies of the Irregular Structure of the Ionosphere using Scattering of Radio Waves on Artificial Periodic Inhomogeneities

We present new results of our studies of the irregular structure of the ionosphere using artificial periodic inhomogeneities (APIs) of the ionospheric plasma. The observations were carried out from 9:00 to 17:00 in August 10–12, 1999 with a height step of 0.7 km and digital registration and real-time processing of the signal quadratures. It is shown that in many cases, the amplitude of the scattered signal is determined by the interference of radio waves scattered on APIs and on natural ionospheric formations including sporadic layers and large-scale natural irregularities. This allows one to study the irregular structure of the lower ionosphere by analyzing height-time dependences of the amplitude and phase of the scattered signal.     

Coupling Coefficient of Irregular Microstrip Resonators

We prove the equivalence of the resonance and energetic definitions of the coupling coefficient in the case of irregular microstrip resonators. Formulas for calculation of the coupling coefficient of microstrip resonators with stepped width of the strip conductor are derived. The presence of a region in which the coupling coefficient increases with increase in spacing between the resonators is shown.     

The Algebraic Structure of the Thirring Model

We summarize the representation theory of the group SU(1,1) as needed for the massless Thirring model. Representations of the current operator algebra are given taking account of conformal covariance. The conformal covariance transformation behaviour of the Thirring field is investigated. The Haag-Araki-Kastler observable algebra of the Thirring field is reconstructed from the Wightman theory of this model.     

Irregular wakes in reaction-diffusion waves

Reaction-diffusion equations have proved to be highly successful models for a wide range of biological and chemical systems, but chaotic solutions have been very rarely documented. We present a new mechanism for generating apparently chaotic spatiotemporal irregularity in such systems, by analysing in detail the bifurcation structure of a particular set of reaction-diffusion equations on an infinite one-dimensional domain, with particular initial conditions. We show that possible solutions include travelling fronts which leave behind either regular or irregular spatiotemporal oscillations. Using a combination of analytical and numerical analysis, we show that the irregular behaviour arises from the instability of oscillations induced by the passage of the front. Finally, we discuss the generality of this mechanism as a way in which spatiotemporal irregularities can arise naturally in reaction-diffusion systems.     

Irregular collective behavior of heterogeneous neural networks

We investigate a network of integrate-and-fire neurons characterized by a distribution of spiking frequencies. Upon increasing the coupling strength, the model exhibits a transition from an asynchronous regime to a nontrivial collective behavior. Numerical simulations of large systems indicate that, at variance with the Kuramoto model, (i) the macroscopic dynamics stays irregular and (ii) the microscopic (single-neuron) evolution is linearly stable.     

Topological Structure of Vortex Solution in Jackiw-Pi Model

By using o-mapping method, we discuss the topological structure of the self-duality solution in Jackiw-Pi model in terms of gauge potential decomposition. We set up relationship between Chern-Simons vortex solution and topological number, which is determined by Hopf index and Brouwer degree. We also give the quantization of flux in this case. Then, we study the angular momentum of the vortex, which can be expressed in terms of the flux.     

Phase Structure of the Semi-Classical Linear Sigma Model

In order to establish a quantitative framework for assessing the reliability of dynamical simulations of DCC phenomena with the semi-classical mean-field treatment of the linear model, we determine and discuss the phase structure implied by this approximate treatment. While the results appear to be physically reasonable for realistic scenarios, where the pion mass and the volume are finite, the approximate treatment might be less appropriate for idealized scenarios involving small masses and large volumes.