Two-dimensional numerical modeling of lightly doped nano-scale double-gate MOSFET

A two-dimensional numerical solution of electrostatic potential and electric field profiles are presented for lightly doped nano-scale Double-Gate Metal-Oxide-Semiconductor-Field-Effect-Transistor (DG-MOSFET). We have developed quasi-static (QS) model for evaluating bulk and inversion charges based on symmetric linearization model. We have also shown the non-quasi-static (NQS) effect on the charge due to a time varying gate voltage. It is seen that various symmetries of DG-MOSFET characteristics with respect to source/drain interchange is maintained in quasi-static as well as non-quasi-static version of the symmetrically linearized model. The variation of the threshold voltage with the varying width of the device is evaluated and presented. The results have been compared and contrasted with reported analytical model for QS condition for the purpose of verification of the model. The variation of threshold voltage along the width of the device is also predicted. This numerical model can be extended to analyze the transport phenomenon in sub 30 nm channel length DG-MOSFETs.     

Far infrared spectrum of methylamine

The far-infrared (FIR) spectrum of CH₃NH₂ has been studied in the 25–125 cm^?1 region at a resolution of 0.005 cm^?1 with a BOMEM Fourier transform spectrometer. All of the^rR branches with K rotational quantum number from 5 to 13 have been identified for A-a and E-a torsion-inversion symmetries in the ground torsional state, as well as some branches of A-s and E-s symmetries and some in excited torsional states. The observed branches have been fitted to series expansions in order to determine the branch origins.     

Analysis of bilateral coplanar waveguides printed on anisotropicsubstrates for use in monolithic MICs

The spectral-domain method is applied to the analysis of bilateral (double-sided) coplanar waveguides that are printed on electric and/or magnetic anisotropic substrates. A nondecoupling approach is used to solve the coupled differential equations for the transverse propagation constants inside the substrate. The dyadic admittance Green's function is derived for both open and shielded bilateral coplanar waveguides, taking into account the anisotropy of the material. Finally, numerical results, describing the propagation characteristics of these structures, are presented for both electric and magnetic wall symmetries     

Power optimization of multi-level logic circuits utilizing circuit symmetries

The property of circuit symmetry has long been applied to the problem of minimizing the area and timing of multi-level logic circuits. In this paper, we focus on another important design objective, power optimization, utilizing circuit symmetries. First, we analyse and establish the relationship between several types of circuit symmetry and their applicability to reducing power consumption of the circuit, proposing a set of re-synthesis techniques utilizing the symmetries. We derive an algorithm for detecting the symmetries (among the internal signals as well as the primary inputs) on a given circuit implementation. We then propose an effective transformation algorithm to minimize power consumption using the symmetry information detected from the circuit. Unlike many other approaches, our transformation algorithm guarantees monotonic improvement in terms of switching activities, which is practically useful in that user can check the intermediate re-synthesized designs in terms of the degree of changes of power, area, timing, and the circuit structure. We have carried out experiments on MCNC benchmark circuits to demonstrate the effectiveness of our algorithm. On average we reduced the power consumption of circuits by 12% with relatively little increase of area and timing.     

Cutoff space of cloverleaf resonators with electric and magneticwalls

A planar resonator that has the symmetry of a junction circulator is the cloverleaf resonator. The isotropic cutoff space of this class of resonator is described using the finite-element approach. Circuits with threefold and fourfold symmetries and with a magnetic or an electric sidewall are separately dealt with. Standing-wave solutions are included for completeness. The gyromagnetic problem is separately investigated     

Three-dimensional edge-based finite-element analysis for discretebodies of revolution

An extension to three-dimensional (3-D) edge-based finite-element analysis for modeling electrically large fan-like bodies as discrete bodies of revolution is given. By exploiting the overlapping symmetries between a fan-like body and a modal expansion of the electromagnetic fields, only one lobe of the problem need be solved by the finite-element method without introducing approximations. This computational scaling makes possible the solution of electrically large structures much more efficiently. However, a periodic phase-boundary condition (PBC) must be applied to the faces of the mesh describing a single slice of the body and this condition must be enforced on both the electric and magnetic fields for a robust solution. Details on the implementation of the PBCs are given along with results which validate the overall technique     

Toroidal Resonators for Electromagnetic Waves--II

A series solution to Maxwell's equations for toroidal geometry has been given. Approximations of the eigenfunctions and of the dispersion relation have been obtained. The existence of two groups of electromagnetic rnodes with different symmetries has been put in evidence.     

Correction To "Variational Solution of Integral Equations"

In the above paper, two errors have been noted. First, the proof of positive-definiteness of the integral operator on page 239 requires that the potential vanish at infinity. This condition should have been stated just before (19b). By virtue of mirror image symmetries all the examples presented satisfy this condition.     

Propagation in periodically loaded waveguides with higher symmetries

A generalization of Floquet's theorem is presented for periodically loaded closed waveguides possessing a certain class of higher symmetries which includes the screw and glide symmetries. These symmetries frequently appear in microwave structures such as filters, traveling-wave tubes, and traveling-wave antennas. The theorem states that the natural modes are eigenvectors of the symmetry operator characterizing the structure. An alternative derivation of the theorem using an equivalent network representation leads naturally to a simple method for constructing the qualitative dispersion (Brillouin) diagrams for structures with screw or glide symmetry.     

Symmetry Study for Delta- Operator-Based 2-D Digital Filters

The complexity in the design and implementation of two-dimensional (2-D) filters can be considerably reduced if we utilize the symmetries that might be present in the frequency response of these filters. As the delta-operator formulation of digital filters offers better numerical accuracy and lower coefficient sensitivity in narrowband filter designs when compared to the traditional shift-operator formulation, it is desirable to have efficient design and implementation techniques in$gamma$-domain which utilize the various symmetries in filter specifications. With this motivation, we comprehensively establish the theory of constraints for delta-operator formulated discrete-time real-coefficient polynomials and functions, arising out of the many types of symmetries in their magnitude responses. We also show that as sampling time tends to zero, the$gamma$-domain symmetry constraints merge with those of$s$-domain symmetry constraints. We then present a least square error criterion based procedure to design 2-D digital filters in$gamma$-domain that utilizes the symmetry properties of the magnitude specification. A design example is provided to illustrate the savings in computational complexity resulting from the use of the$gamma$-domain symmetry constraints.     

Symmetry-Induced Modal Characteristics of Uniform Waveguides --- I: Summary of Results

The application of symmetry analysis to uniform waveguides is discussed. Symmetry analysis provides exact information concerning mode classification, mode degeneracy, modal electromagnetic-field symmetries, and the minimum waveguide sectors which completely determine the modes in each mode class. Tables are presented which list the possible mode classes and their degeneracies for the two general symmetry families, C/sub n/ and C/sub nv/, of uniform waveguides. Tables showing the azimuthal dependence of the longitudinal components of the electric and magnetic fields for each mode class are given. Based on this azimuthal dependence, figures showing the minimum waveguide sectors which are necessary and sufficient to completely determine the modes of the various mode classes are presented. The application of symmetry analysis is illustrated by considering uniform waveguides with C/sub 4/ and C/sub 6v/ symmetry.     

Electron holography study of electric field variations

This paper presents a review of the recent electron holography studies on electric field variation that have been carried out using multifunctional specimen holders. In addition to the standard inner potential analysis, studies on electric field variations around field emission tips have been carried out. The electric field variations caused by ballistic emission in the case of a field emitter made of a TaSi(2) nanowire have been analyzed using electron holography. The charges and electric fields in electrophotographic materials such as toner particles and organic photoconductors have been quantitatively evaluated after equipping the specimen holder with a piezodriving probe to shield the specimens from electron irradiation. The conductivity and electric field variations in the case of Ag-based conductive adhesives have been analyzed by applying an electric current through the holder. Finally, the characteristic charging effect induced by electron irradiation in biological specimens has been studied. It has also been pointed out that under certain experimental conditions, the stationary orbits of electron-induced secondary electrons can be located by electric field visualization.     

Formative Mechanisms of Current Concentration and Breakdown Phenomena Dependent on Direct Current Flow Through the Skin by a Dry Electrode

Direct current flow into the skin by dry electrode is useful in the fields of the electrocutaneous stimulation in sensory substitution systems and the probing of acupuncture points by means of electric resistance. During such. use, both the occurrences of a pain sensation and the electric breakdown of the skin become a hindrance to application. Equations describing these phenomena have been derived and the formative mechanisms of three phenomena, namely the current concentration in a minutely localized region, the occurrence of pain sensation as a result of heat generation, and the electric breakdown of the skin, have been made clear. The impottant values from which the key to solutions for these problems can be concretely obtained using equations are discussed in detail.     

Elliptic and almost hyperbolic symmetries for the Woodwardambiguity function [radar]

The authors deal with the radar ambiguity functions and their symmetries. It is well known that Hermite functions give rise to elliptic symmetries. Hermite functions are eigenvectors of the harmonic-oscillator Schrodinger operator. It is shown that the situation is essentially the same for hyperbolic symmetries: the signals are eigenvectors of the Schrodinger operator associated to the hyperbolic oscillator. Since this operator has continuous spectrum, these symmetries can only be reached approximately. It is also shown how to construct such signals and their ambiguity functions, which fall in two classes, are given. This work is essentially abstract nilpotent harmonic analysis, and is based on the well-known main fact that the Woodward ambiguity function is a positive-type function on the real Heisenberg Lie group     

Electric field effects on an optically-pumped HCOOH FIR laser and Zeeman laser theory

Electric field effects have been investigated on the output power of six far-infrared (FIR) laser lines from H¹²COOH optically-pumped by a CO₂ laser with its polarization arranged perpendicular to the Stark field. Optoacoustic signals observed on the pump lines were hardly affected by the applied electric field up to 0.6 kV/cm. By neglecting the electric field effects on the pump transitions, Zeeman laser theory has been applied to the FIR laser transitions. Numerical calculation predicts the observed FIR output power as a function of electric field. Experessions for oscillation frequency and intensity in homogeneous limit are given, which may be applicable to any FIR Stark laser so far as the pump transition is free from electric field effects.     

内建电场对应变多量子阱带阶的影响

隧穿电流的大小依赖于带阶的大小。内建电场会改变多量子阱的结构 ,使其由方阱变为斜阱 ,导致其带阶发生改变。本文定量地给出了由内建电场导致的价带阶变化及其斜率。对沿任意方向生长的立方超晶格系统 ,当其特征厚度小于临界值 (欠临界系统 )时 ,给出了内建电场与应变的定量关系。针对不同的量子阱系统 ,当生长方向沿着 [111]方向时 ,计算了三种类型、2 1种组分、由内建电场引起的价带阶变化量。所有结果在线性领域及没有相变的情况下都是适用的。     

一种具有自然偏置点的集成光学电场传感器

讨论了一种通过在铌酸锂衬底上制备非对称Mach-Zehnder干涉仪结构的光波导,得到具有自然偏置点的电场传感器.讨论了该器件主要参数的理论设计方案和工艺设计方案,并对试验结果进行了分析.     

Limitations of sum-of-sinusoids fading channel simulators

Rayleigh signal fading due to multipath propagation in wireless channels is widely modeled using sum-of-sinusoids simulators. In particular, Jakes' (1994) simulator and derivatives of Jakes' simulator have gained widespread acceptance. Despite this, few in-depth studies of the simulators' statistical behavior have been reported in the literature. Here, the extent to which Jakes' simulator adequately models the multipath Rayleigh fading propagation environment is examined. The results show that Jakes' simulator does not reproduce some important properties of the physical fading channel. Some possible improvements to Jakes' simulator are examined. The significances of the number and the symmetries of the Doppler frequency shifts on the validity of the simulator's reproduction of the physical fading channel are elucidated     

Unified theory of symmetry for two-dimensional complex polynomials using delta discrete-time operator

The complexity in the design and implementation of 2-D filters can be reduced considerably if the symmetries that might be present in the frequency responses of these filters are utilized. As the delta operator (??-domain) formulation of digital filters offers better numerical accuracy and lower coefficient sensitivity in narrow-band filter designs when compared to the traditional shift-operator formulation, it is desirable to have efficient design and implementation techniques in ??-domain which utilize the various symmetries in the filter specifications. Furthermore, with the delta operator formulation, the discrete-time systems and results converge to their continuous-time counterparts as the sampling periods tend to zero. So a unifying theory can be established for both discrete- and continuous-time systems using the delta operator approach. With these motivations, we comprehensively establish the unifying symmetry theory for delta-operator formulated discrete-time complex-coefficient 2-D polynomials and functions, arising out of the many types of symmetries in their magnitude responses. The derived symmetry results merge with the s-domain results when the sampling periods tend to zero, and are more general than the real-coefficient results presented earlier. An example is provided to illustrate the use of the symmetry constraints in the design of a 2-D IIR filter with complex coefficients. For the narrow-band filter in the example, it can be seen that the ??-domain transfer function possesses better sensitivity to coefficient rounding than the z-domain counterpart.