Influence of relative phase on propagation effect in open V-type three-level system

In this paper we study the influence of the relative phase between the probe and driving fields on propagation effect in an open Doppler broadening V-type three-level atomic system with spontaneously generated coherence(SGC) by using the calculation result of the density matrix motion equations and the propagation equations of the driving and probe fields.It is shown that the relative phase(Φ) has remarkable periodical influence on the propagation effect,and the period is 2π.By selecting appropriate value of Φ,we can get larger lasing without in version(LWI) gain and longer propagation distance in which gain exists,and hence obtain higher probe field(i.e.LWI) intensity.When Φ=π/2,the largest LWI gain and probe field intensity can be got.In addition,the atomic exit rate(γ0) and ratio(S) of the atomic injection rates also have a considerable modulation role on the phase-dependent propagation effect.In certain value range of γ0(S),LWI gain and probe field intensity increase with γ0(S) increasing.In the open system,LWI gain and probe field intensity much larger than those in the corresponding closed system can be obtained.     

Delay-Dependent Robust H ∞ Filtering for Uncertain Neutral Stochastic Time-Delay Systems

This paper is concerned with the problem of robust H _∞ filtering for neutral stochastic time-delay systems with norm-bounded parameter uncertainties. By introducing appropriate slack matrix variables, both a delay-dependent stochastic stability condition and a delay-dependent bounded real lemma are obtained in terms of linear matrix inequalities. A delay-dependent condition for the solvability of the robust H _∞ filtering problem is also proposed. Desired H _∞ filters are designed that guarantee the filtering error system to be robustly stochastically stable and satisfy a prescribed H _∞ performance level for all admissible uncertainties. A numerical example is provided to demonstrate the effectiveness of the proposed approach. This work is supported by the National Science Foundation for Distinguished Young Scholars of People’s Republic of China under Grant 60625303, the Specialized Research Fund for the Doctoral Program of Higher Education under Grant 20060288021, and the Natural Science Foundation of Jiangsu Province under Grant BK2008047.     

Influence of reaction temperature on the formation process of ZnO quantum dots and the optical properties

ZnO quantum dots (QDs)with the sizes of 3.0-5.6 nm are synthesized by solution-phase method at different temperatures. We find that temperature has great influence on the size of ZnO QDs. The growth process is the most sensitive to temperature, and the process is well explained by Lifshitz-Slyozov-Wagner (LSW) model. By photoluminescence (PL) spectra of the quantum dots at different temperatures and reactive time, we come to a conclusion that ultraviolet emission is mainly due to surface defects, and the or...     

High power output quasi-continuous-wave nanosecond optical parametric generator based on periodically poled lithium niobate

We report on a high power output quasi-continuous-wave nanosecond optical parametric generator （OPG） of congruent periodically poled lithium niobate （PPLN） pumped by a 1 064 nm acousto-optically Q-switched Nd-YVO4 laser （duration. 70 ns,repetition rate：45 kHz,spatial beam quality M2〈 1,3）. The OPG consists of a 38.7 mm long PPLN crystal with a domain period of 28.93 μm. With 5.43 W of average pump power the maximum average output power is 991 mW at 1 517.1 nm signal wave of the PPLN OPG.     

Output Feedback H ∞ Control for 2-D State-Delayed Systems

In this paper, we consider a class of two-dimensional (2-D) local state-space (LSS) Fornasini–Marchesini (FM) second models with delays in the states, and we study delay-independent and delay-dependent H _∞ control problems via output feedback. First, based on the definition of H _∞ disturbance attenuation γ for 2-D state-delayed systems, we propose a delay-dependent bounded real lemma. Specifically, a new Lyapunov functional candidate is introduced and free-weighting matrices are added to the difference Lyapunov functional for 2-D systems possessing two directions. Then delay-independent and delay-dependent output feedback H _∞ controllers are developed that ensure that the closed-loop system is asymptotically stable and has H _∞ performance γ in terms of linear matrix inequality (LMI) feasibility. Furthermore, the minimum H _∞ norm bound γ is obtained by solving linear objective optimization problems. Numerical examples demonstrate the effectiveness and advantages of the LMI approach to H _∞ control problems for 2-D state-delayed systems. This work was supported in part by the National Natural Science Foundation of China (60525303 and 60604004), NSF of Hebei Province (08M008) and the Key Scientific Research Project of the Education Ministry (204014).     

H ∞ Fuzzy Filtering for Discrete-Time Nonlinear Systems via Fuzzy Lyapunov Function Approach

This paper is concerned with the H _∞ fuzzy filtering problem for a class of discrete-time fuzzy systems. The objective is to design a stable filter guaranteeing the asymptotic stability and a prescribed H _∞ performance of the filtering error system. Motivated by the parallel distributed compensation (PDC) technique, a new filter model is proposed in this paper. Both full-order and reduced-order filters are established, and they can be obtained from the solution of convex optimization problems in terms of linear matrix inequalities (LMIs). When these LMIs are feasible, an explicit expression of a desired H _∞ fuzzy filter is given. A numerical example is provided to demonstrate the effectiveness and applicability of the proposed design approach. This work was supported by the National Natural Science Foundation of China under Grant 60504020 and the Excellent Young Scholars Research Fund of the Beijing Institute of Technology 2006y0103, respectively.     

Robust H ∞ Filtering for 2-D Systems with Intermittent Measurements

This paper is concerned with the problem of robust H _∞ filtering for uncertain two-dimensional (2-D) systems with intermittent measurements. The parameter uncertainty is assumed to be of polytopic type, and the measurements transmission is assumed to be imperfect, which is modeled by a stochastic variable satisfying the Bernoulli random binary distribution. Our attention is focused on the design of an H _∞ filter such that the filtering error system is stochastically stable and preserves a guaranteed H _∞ performance. This problem is solved in the parameter-dependent framework, which is much less conservative than the quadratic approach. By introducing some slack matrix variables, the coupling between the positive definite matrices and the system matrices is eliminated, which greatly facilitates the filter design procedure. The corresponding results are established in terms of linear matrix inequalities, which can be easily tested by using standard numerical software. An example is provided to show the effectiveness of the proposed approach. This work was partially supported by the National Natural Science Fundation of China under Grant 60504008 and 60825303, by the Research Fund for the Doctoral Program of Higher Education of China under Grant 20070213084, and by the Fok Ying Tung Education Foundation (111064).     

l 2–l ∞ Filtering for Multirate Systems Based on Lifted Models

For a multirate sample-data system where the output sampling rate is slower than the input updating rate, we study the l ₂–l _∞ filtering problems for fast state estimation by using the lifted model. The filtering problem is handled in the framework of linear matrix inequalities (LMIs) with a nonconvex constraint, which is numerically solved by the product reduction algorithm. Finally, the effectiveness of the proposed method is illustrated and verified by simulation examples. This research was supported by the Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation and the National Natural Science Foundation of China (60372105 and 60672118).     

Effects of spontaneously generally coherence on probe response in an open lambda type system

Quantum coherence and interference in atomic sys-tems have led to a number of i mportant consequences,such as lasing without inversion(LWI),coherent popu-lation trapping(CPT),potentiality for sensitive meas-urements of magnetic fields,the electromagnetica…     

A neural-based nonlinear L 1-norm optimization algorithm for diagnosis of networks

Based on exact penalty function, a new neural network for solving the L ₁-norm optimization problem is proposed. In comparison with Kennedy and Chua’s network(1988), it has better properties.Based on Bandler’s fault location method(1982), a new nonlinearly constrained L ₁-norm problem is developed. It can be solved with less computing time through only one optimization processing. The proposed neural network can be used to solve the analog diagnosis L ₁ problem. The validity of the proposed neural networks and the fault location L ₁ method are illustrated by extensive computer simulations. Supported by Doctoral Special Fund of State Education Commission and the National Natural Science Foundation of China, Grant No.59477001 and No.59707002     

Electron effective mass in InuGa1−uPvAs1−v for 0 ≤ v ≤ 1

The electron effective mass in In_uGa_1−uP_vAs_1−v has been measured on seven samples lattice-matched to InP and evenly spaced in values of v between 0 and 1, using the temperature dependence of the amplitude of the Shubnikov-de Haas oscillations at high magnetic fields. Values of the carrier concentrations, Hall mobilities and Dingle temperatures measured on these samples are also reported. Work sponsored in part by the National Science Foundation, Grant No. ENG 76-09586, and in part by International Telephone and Telegraph Electro-Optical Products Division. Work done in part at the M.I.T. Francis Bitter National Magnet Laboratory. Funded in part by the National Science Foundation under Grant No. DMR-76-80895.     

Improvement of nonrepudiable threshold multi-proxy threshold multi-signature scheme with shared verification

In 2005, Bao, et al. [Appl. Math. and Comput., vol.169, No.2, 2005] showed that Tzeng, et al.’s nonrepudiable threshold multi-proxy multi-signature scheme with shared verification was insecure, and proposed an improved scheme with no Share Distribution Center (SDC). This paper shows that Bao, et al.’s scheme suffers from the proxy relationship inversion attack and forgery attack, and pro- poses an improvement of Bao, et al.’s scheme.     

Flicker phase noise in transistorized amplifier

In this article, the relation between the frequency stability due to the flicker phase noise (phase-power spectrum densityS _Δϕ1'(f) in frequency domain and Allen variance γ _y ² {τ} in time domain) and the parameters of the transistors has been derived and experimentally verified.     

MEASURING HIGH-ORDER VOLTERRA KERNELS ALONG AXES

A fast and efficient method for measuring high-order Volterra kernels along axes is given. This is a sequel of the authors' former paper(1990). Using the conclusions of those papers mentioned above, and combining the DC component with the input signals, the high-order kernels of nonlinear system H2(jω,0), H3(jω,0,0), H3(Jω,jω2,0) can be measured at many points.     

Influence of strain on hydrogenic impurity states in a GaN/AlxGa1?xN quantum dot

Within the effective-mass approximation, we calculated the influence of strain on the binding energy of a hydrogenic donor impurity by a variational approach in a cylindrical wurtzite GaN/Al _x Ga_1−x N strained quantum dot, including the strong builtin electric field effect due to the spontaneous and piezoelectric polarization. The results show that the binding energy of impurity decreases when the strain is considered. Then the built-in electric field becomes bigger with the Al content increasing and the binding energy of hydrogenic donor impurity decreases when the Al content is increasing. For dot height L < 2 nm, the change of the binding energy is very small with the Al content variety. This work has been supported by the National Natural Science Foundation of China (No. 10564003) and the Key Project of the Science and Technology Research of the Educational Ministry of China (No. 208025)     

Functional inversion and communication complexity

We study the relationship between the multiparty communication complexity of functions over certain communication topologies and the complexity of inverting those functions. We show that if a function ofn variables has aring-protocol or atree-protocol of communication complexity bounded by ϕ, then there is a circuit of size that computes an inverse of the function. Consequently, we prove that although invertingNC ⁰ Boolean circuits isNP-hard, planarNC ¹ Boolean circuits can be inverted inNC, and hence in polynomial time. From the ring-protocol theorem, we derive an ω(n logn) lower bound on the VLSI area required to lay out any one-way function. Our results on inverting boolean circuits can be extended to algebraic circuits over finite rings. We prove that on certain topologies no one-way function can be computed with low communication complexity. The preliminary version of this paper appeared inCRYPTO 91. This work was supported in part by National Science Foundation Grant DCR-8713489. Part of this work was done while the author was at the School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15213, U.S.A. Current address: Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.     

A new algorithm for electromagnetic scattering of multilayered sphere

More stable and accurate recursive formulas and a computing procedure for scat-tering coefficient calculation of a multilayered sphere are proposed, This procedure involves threelogarithmic derivatives of Ricatti-Bessel function ψ_n~＇(z)/ ψ_n(z), X_n~＇(z)/X_n(z),ξ_n~＇(z)/ ξ_n(z), as wellas the ratioψ_n(z)/X_n(z). The asymptotic behavior, stability, and accuracy of the procedureand scattering coefficients a_n and b_n are discussed for various complex refractive indices. Thisprocedure can be applied to large and small inhomogeneous spherical particles.     

High stable power control of a laser diode

For a high precise sensing and measuring system,theerror of measurement resulting fromthe fluctuation ofthe light source must be considered[1-3].The main noisesources include fluctuation of current source,self-heat ,aging and theintrinsic noises of a lase…     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

A Delay-Dependent Approach to Robust H ∞ Control for Uncertain Stochastic Systems with State and Input Delays

In this paper, the problem of delay-dependent robust H _∞ control for uncertain stochastic systems with state and input delays is investigated. The time delays are assumed to be bounded and time varying and the uncertainties are assumed to be norm bounded. By using the Lyapunov functional method, a new delay-dependent robust H _∞ control scheme is presented in terms of linear matrix inequalities (LMIs). Some numerical examples are given to illustrate the effectiveness of the proposed approach. This work is partially supported by the Natural Science Foundation of China (60674055, 60774047), and the Taishan Scholar Programme of Shandong Province. An erratum to this article can be found at