A VLSI structure forX(modm) operation

High-computing speed and modularity have made RNS-based arithmetic processors attractive for a long time, especially in signal processing, where additions and multiplications are very frequent. The VLSI technology renewed this interest because RNS-based circuits are becoming more feasible; however, intermodular operations degradate their performance and a great effort results on this topic. In this paper, we deal with the problem of performing the basic operationX(modm), that is the remainder of the integer divisionX/m, for large values of the integerX, following an approximating and correcting approach, which guarantees the correctness of the result.We also define a structure to computeX(modm) by means of few fast VLSI binary multipliers, which is exemplified for 32-bit long numbers, obtaining a total response time lower than 200 nsec. Furthermore, such a structure is evaluated in terms of VLSI complexity and area and time figuresA=(n ² T _m ² ) andT=(T _M ) for the parameterT _M in are derived. A simple positional-to-residue converter is finally presented, based on this structure; it improves some complexity results previously obtained by authors.This work has been supported by the National Program on Solid-State Electronics and Devices of the Italian National Research Council.     

Resonant Γ-<Emphasis Type="Italic">X</Emphasis> tunneling in single-barrier GaAs/AlAs/GaAs heterostructures

The electron transport through single-barrier GaAs/AlAs/GaAs heterostructures is studied. This transport is caused by resonant tunneling between the two-dimensional states related to the Γ valley of the GaAs conduction band and various two-or zero-dimensional donor states related to the lower X valleys of the AlAs conduction band. The resonant electron tunneling both via various two-dimensional states related to the X_z and X_xy valleys in AlAs (the X_z and X_xy states) and via related states of Si donors X _z ^D and X _xy ^D was observed. This circumstance made it possible to determine the binding energies of these states (E_B(X _z ^D )≈50 meV and E_B(X _xy ^D )≈70 meV, respectively) directly from the results of identification of resonance features in transport characteristics. An analysis of the structure of experimental resonances corresponding to tunneling between the Γ and X Landau levels in a magnetic field made it possible to determine the transverse effective mass in the X valleys of AlAs (m_t=(0.2±0.02)m₀). An additional fine structure of donor resonances is observed in experimental transport characteristics. This fine structure is caused by resonant tunneling of electrons through the states of the donors that are located in various atomic layers of the AlAs barrier (in the growth direction) and therefore have different binding energies.     

Structure theorems for nonlinear systems

One of the main results is a proposition to the effect that under some typically mild conditions finite sums of the form $$\sum\limits_\ell {K_\ell \sigma } \left[ {\sum\limits_m {\eta _{\ell m} Q_m (\cdot) + \rho _\ell } } \right]$$ are dense in an important sense in the set of shift-invariant approximately-finite-memory mapsG(·) that take a certain type of subsetU ofR intoR, whereR is the set of real-valued functions defined onR ⁿ orZ ⁿ . Here theQ _m (·) are linear, σ is any element of a certain set of nonlinear maps fromR toR, and the κ_?, ρ_?, and η_?m are real constants. Approximate representations comprising only affine elements and lattice nonlinearities are also presented.     

Détermination du facteur de multiplication M pour un fonctionnement optimal des photodétecteurs à avalanche

The purpose of this paper is relative to the determination of the multiplication factor Mfor an optimum behaviour of the avalanche photodetector. Two types of avalanche photodetector s are compared: a silicon structure n ⁺ πpπp ⁺ Read diode and a GaAlAs heterostructure. Calculating the Noise Equivalent Power (nep)of the whole system, the law S_i(f) =2q I_phoM_x is used, where the parameter x is determined experimentally in both avalanche photodetectors. The exponent x (between 2 and 4) dominates in the nep expression and the ideal nep for the avalanche photodetector system is obtained when x equals 2.     

Die Bestimmung der KabelkopplungsparameterZ T ′ undY T ′ und ihr Wert für die EMV-Analyse

In EMC analysis, shielded cables are best characterized by a peculiar set of coupling parameters: the transfer impedanceZ _T ^′ , and the transfer admittanceY _T ^′ or the radial electric coupling coefficient ζ_R. Here, a way is shown how to measure these parameters and two examples are given of applying these parameters in practice.     

Electron-phonon damping factor for the landau quantization of 2D electrons with a fine structure of the energy spectrum

The drift of degenerate 2D electrons in the channel of the heterojunction potential well is considered. In a quantizing magnetic field B, the electrons scan the defects of the heteroboundary, which perturb their momentum and energy equilibrium state (T, T _D ⁰ ). The stationary nonequilibrium state (T, T _D ^* ) is attained by electron-phonon relaxation in energy and momentum. The experimentally observed nonlinear dependence T_D(T) is explained by the admixture of deformation acoustic phonons to the interaction of 2D electrons with piezoelectric phonons.     

Linear photovoltaic effect in gyrotropic crystals

The ballistic and shift linear photovoltaic effects caused by asymmetry of the probability of optical transitions between subbands M ₁ ^′ and M ₂ ^′ in tellurium (involving long-wave optical phonons) and by carrier shift in real space at quantum transitions, respectively, are considered. The temperature and frequency dependences of the current of both ballistic and shift linear photovoltaic effects for the photon and phonon mechanisms are analyzed.     

Tunneling effects in tilted magnetic fields in n-InGaAs/GaAs structures with strongly coupled double quantum wells

The effects of tunneling between two parallel two-dimensional electron gases in n-InGaAs/GaAs nanostructures with strongly coupled double quantum wells with a change in the in-plane component of a tilted magnetic field (up to B _‖ = 9.0 T) in the temperature range T = 1.8–70.0 K are investigated. A nonmonotonic temperature dependence of the inverse quantum lifetime τ _q ^? (T) is obtained from analysis of the dependence of the longitudinal resistance on the parallel component of the tilted magnetic field at fixed temperatures, ρ _xx (B _‖, T). The quadratic portion of this dependence is found to be due to the contribution of inelastic electron-electron scattering. The decrease in the inverse quantum lifetime τ _q ^? (T) at T > 0.1T _F cannot be described within known theories; it seems, it is not related to the processes of electron momentum relaxation.     

Study of the spectrum of CH3 35C1 between 4250 and 4600 CM−1: thev 2+v 4 andv 4+v 5 rovibrational bands

About 2500 lines of CH₃ ³⁵Cl have been assigned. The strong xy Coriolis resonance between thev ₂ andv ₅ modes is quite visible between thev ₄+v ₄ ^±1 perpendicular band, centered around 4383 cm^?1, and thev ₄ ^±1 +v ₅ ^±1 perpendicular component, centered around 4475 cm^?1, with a crossing of upper energy levels allowing the observation of lines which are normally forbidden. Although not yet observed with certainty, because of the great density of lines of the spectrum, thev ₄ ^?1 +v ₅ ^±1 parallel component is nevertheless detectable by its effects onv ₂+v ₄ ^±1 which is linked by Coriolis resonance to both components ofv ₄+v ₅. Moreover the spectrum is much complicated by many other resonances with weak bands which occur at level crossings: it is the case ofv ₂+3v ₆ ^±1 , connected tov ₂+v ₄ ^±1 by the well known Darling Dennison resonance which couplesv ₄ ^±1 and 3v ₆ ^±1 , and also ofv ₅ ^±1 +3v ₆ ^±1 connected tov ₄ ^±1 +v ₅ ^±1 by the same resonance; but this last case is complicated by an anharmonic resonance betweenv ₅ ^±1 +3v ₆ ^±1 and 2v ₃+3v ₆ ^?1 . Two more perturbations occur on the ΔK=?1 side ofv ₂+v ₄: a weak Coriolis resonance gives rise to one subband ofv ₁+v ₂ at a level crossing withv ₂+v ₄, and thev ₁+v ₅ band (linked of course tov ₁+v ₂ by the Coriolis resonance between thev ₂ andv ₅ modes) is quite visible and perturbs several subbands ofv ₂+v ₄ of high values of K through an anharmonic resonance. Moreover, the complex (3v ₅ ^±1 ,v+2v ₅ ⁰ , 2v ₂+v ₅ ^±1 , 3v ₂,v ₂+2v ₅ ^±2 , 3v ₅ ^±3 ) system of Coriolis-connected bands is linked to the bands studied in the present work by two Fermi resonances: one betweenv ₂+2v ₅ ⁰ andv ₁+v ₂, and the other one betweenv ₁+v ₅ and 3v ₅ ^±1 , whose several subbands have been observed on the low part of the spectrum. The values of all the band centres and of the different coupling constants have been estimated, but all these interactions make the line assignments and the interpretation of the spectrum very difficult.     

The Electrical Conductivity of Strontium-Barium Niobate

We propose an explanation for the high electrical conductivity of the ferroelectric strontium-barium niobate. As the temperature T approaches the ferroelectric transition T _c, the static dielectric constant $\varepsilon(0)$ diverges when a soft mode occurs. This divergence of $\varepsilon(0)$ reduces the donor binding energy, and increases the effective Bohr radius of the donor. The electrons bound to the donors become unbound, and the material becomes conductive.     

Quantized IR properties reconfirmed in the CO and SiO surface oscillators present in the surface layer of A bamboo stem

From analysis of diffusion diagrams of CO stretching band (2500～2180 cm^?1), bending band (800～200 cm^?1) and SiO stretching band (1100～700 cm^?1) measured in a skin surface layer of a bamboo stem (silicate cellulose), azimuthal directions where oscillators oriented were shown as (?'=?-90) ?_N=a·N-b, with a=28.3, 2×28, 22.7, b=25, 47.5, 10. And N=1,2.....14, N=1, .....6. N=1,2.....16. The optical activity (reflection integral) was shown for the CO stret. band as M_i(N)=a·N+b, with a=21.8, b=42 and N =1,2.....9. And for the bending band as M_i(N)=a·N² +b·N?c, with a=1.87×10¹, b=3.73×10³, c=7.06×10² with N=1,2.....9. Six stepnized fine series in CO weak reflection bands were confirmed as, \(\bar v = A \cdot N^2 + B \cdot N + C (cm^{ - 1} )\) and \(\bar v_{C - 1} = A \cdot N^{1/2} + B (cm^{ - 1} )\) with N=1,2.....22. Mean values of the vibrational quantized states of the A, B and C-series in the SiO stretching weak band with R?1.0% were shown as, \(\overline {\Delta E} _m = 4.54 \times \bar v_{\text{m}}^{\text{2}} - 1.449 \times \bar v_m + 1.27 \times 10^7 \) (meV) with \(\bar v = E/hc\) .     

Electronic and optical properties of AlAs/Al<Subscript>x</Subscript>Ga<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>As(110) superlattices

Electronic states in the conduction band of (AlAs)_M(Al_xGa_1?xAs)_N(110) superlattices are investigated for various M and N. It is shown that electronic properties of these structures are mainly determined by electrons of two pairs of valleys, namely, either Γ-X ^Z or X ^X –X ^Y . Calculations based on the developed model of joining the envelope functions were carried out. Miniband spectra, symmetry, and localization of wave functions, as well as probabilities of miniband-to-miniband infrared absorption, are determined and analyzed. It is shown that, in the case of the X ^X –X ^Y pair of valleys, the absorption probabilities are high not only for polarization of light along the growth axis of the superlattice but also for the normal incidence of an optical wave on the structure surface.     

New entangled state representation and its characteristics for the three compatible operators

The eigenvector set of ︱φ2(x,r1,r2)with three compatible operators(1+2+3,p2+p3-2p1 and p3-p2) is constructed by virtue of Radon transformation of the Wigner operator and the technique of integration within an ordered product(IWOP) of operators.Its entanglement property is then revealed by deriving its standard Schmidt decomposition.︱φ2(x,r1,r2) makes up a new quantum mechanical representation.A new three-mode squeezing operator is found by using this entangled state representation.     

Investigation of vacancy-type complexes in GaN and AlN using positron annihilation

The momentum distribution of electron-positron pairs in GaN and AlN has been investigated for the first time by measuring the one-dimensional angular correlation of the annihilation radiation (1D-ACAR). The characteristic parameter of the electron density r _s ^′ (the radius of the sphere occupied by an electron) estimated from the experimental data differs noticeably from r _s calculated in terms of a standard model of noninteracting particles: r _s ^′ (AlN)≈1.28r _s, and r _s ^′ (GaN)≈1.66r _s, where r _s(AlN)≈1.6091 au, and r _s(GaN)≈1.6568 au. The chemical nature of atoms in the environment of the annihilating positron in AlN and GaN was identified from the electron-positron ionic radius of Al³⁺, Ga³⁺, and N⁵⁺ cores, which were determined from the characteristics of the high-momentum component of 1D-ACAR curves. The analysis was based on a comparison of the electron-positron ionic radii with those considered standard for Al and Ga metals and the related compounds GaP, GaAs, and GaSb. A conclusion is made that positron annihilation dominates in the regions of vacancy-type “nitrogen antisite”-“vacancy” complexes, [N _Ga ⁺ V _Ga] and [N _Al ⁺ V _Al], in GaN and AlN, respectively.     

TE On o -to- mode transducer designmode transducer design

This paper gives a structure on the mode converter from TE _0n ^O mode of gyrotron output to the main mode of the circular groove guide. The design consists of two parts: the first part is to convert TE _0n ^O to TE ₀₁ ^O using an advanced periodic wall perturbation technology, the second part is to convert TE ₀₁ ^O to mode basing on the method of gradually changing the wave guide cross section. An example at 37.5Ghz is given. For the first part, the efficiency is 94.71%, the length is 1.868m. For the second part, the theoretic figure of reflectance coefficient vs. frequency is given.     

Basis arrays and successive packing for M-D interleaving

In this paper, we first present a novel concept of 2-D basis interleaving array (also referred to as basis array for short). That is, an m × m interleaved array is said to be a basis array if the shortest distance among all pairs of elements in each of the so-called m-equivalent sets within the m × m array reaches the maximum. It is shown that this maximum is given by ${\lfloor \sqrt{2m} \rfloor}$ and an m × m basis array can be constructed by using a simple cyclic translation method. The previously developed concept of successive packing is then generalized in the sense that it can be applied to any basis array to generate an interleaved array with a larger size. Except that optimality cannot be guaranteed, the concept of basis arrays and successive packing are extended to M-D cases. It is shown that for any M ?? 2, the proposed technique can spread any error burst of block size ${m_{1}^{k} \times m_{2}^{k} \times \cdots \times m_{M}^{k}}$ within an ${ m_{1}^{n} \times m_{2}^{n} \times \cdots \times m_{M}^{n}}$ array (1 ?? k ?? n?1) so effectively that the error burst can be corrected with some simple random error-correcting code (provided the error-correcting code is available). It is shown that important prior results in M-D interleaving such as the t-interleaved array based approach by Blaum et al. and the successive packing approach by Shi and Zhang now become special cases of the framework based on basis arrays and successive packing, proposed in this paper.     

I–V characteristics and the spectrum width during electron tunneling through nanosandwiches W-WO2-(Au 147 ? )-Al2O3-Al and Nd-Nd2O3-(Au 55 ? )-Nd2O3-Nd. Part I: Quantum-chemical calculation of energies of orbitals for anions of nanoclusters Au55 and Au147

This work is devoted to the investigation of electron tunneling through ??magical?? nanoclusters Au₅₅ and Au₁₄₇. Using the quantum-chemical calculation, it is shown that the energy of the highest occupied molecular orbital (HOMO) level is ${E_{HOMOAu5{5^ - }}} = - 3.2eV$ and E _HOMOAu147 = ?4.4 eV, respectively. It is established that the difference between energy E _LUMO ^? of the lowest unoccupied level LUMO and energy E _LUMO ^? for the anions of clusters (Au ₅₅ ^? and Au ₁₄₇ ^? ) is 0.86 and 0.24 eV, respectively. Based on the results of the calculations, it is assumed that nanosandwiches W-WO₂-(Au ₁₄₇ ^? )-Al₂O₃-Al can be promising structures for implementation of metal nanodiodes based on them, while nanosandwiches Nd-Nd₂O₃-(Au ₅₅ ^? )-Nd₂O₃-Nd can be promising for implementation of energy filters not producing hot electrons and allowing the fabrication of the ring Aharonov-Bohm interferometers based on normal metals at liquid-helium temperatures.     

On the stability of real exponential polynomials with interval-valued delays

We consider the family ? of exponential polynomials. $$f_T (z): = f_0 (z) + f_1 (z)e^{ - zT_1 } + f_2 (z)e^{ - T_2 } + \cdots + f_n (z)e^{ - zT_n } ,T : = T_1 \times T_2 \times \cdots \times T_n ,$$ where thef _k(z),k=0(1)n, are real polynomials under the degree restriction deg(f ₀)>deg(f _k),k=1(1)n, and theT _k,k=1(1)n, are intervals inR ₊. The functions in ? are characteristic functions of linear, retarded dynamical systems with constant coefficients and finitely many interval-valued discrete delays. A stability criterion for ? is expounded; ? is stable if (a) ? contains a stable member and (b) a certain functionalT:S(y) →; {0, 1} vanishes fory in a compact interval inR ₊. Here,S(y) is the boundary of a circular are regionS(y) in the complex plane derived fromf _T. Tools needed for a computer implementation are compiled.