Variation of Different Characteristic Parameters of Pentacene/Poly（Methyl Methacrylate） Transistors under Electric Stress

By investigating the variation of different characteristic parameters of pentacene/poly（methyl methacrylate） transistors suffered from electric stress in an environment without O2, H2O and light, we deduce lifetimes of the transistors by different criterion parameters. Defined by the time for the parameters changing one half, the lifetime is different from the minimum of 7h （using on/off current ratio as the criterion parameter） to the maximum of 2.38 ×10^8h （using transconductance as the criterion parameter）. We also find that, under our experimental conditions, the main reason that affects the stabilities of the device is the increase of shallow traps formed in the organic semiconductors.     

Separability of Pure and Mixed States of the Quantum Network of Four Nodes

This article discusses the separability of the pure and mixed states of the quantum network of four nodes by means of the criterion of entanglement in terms of the covariance correlation tensor in quantum network theory.     

Symmetry of Lagrangians of nonholonomic systems of non-Chetaev’s type

This paper studies the symmetry of Lagrangians of nonholonomic systems of non-Chetaev's type. First, the definition and the criterion of the symmetry of the system are given. Secondly, it obtains the condition under which there exists a conserved quantity and the form of the conserved quantity. Finally, an example is shown to illustrate the application of the result.     

Stability of Motion of a Nonholonomic System

Perturbation differential equations of motion of a general nonholonomic system subjected to the ideal nonholonomic constraints of Chetaev＇s type are established, and the equation of variation of energy is deduced by using the perturbation equations of the system. A criterion of the stability is obtained and an example is given to illustrate the application of the result.     

Complete Synchronization of Coupled Hindmarsh-Rose Neurons with Ring Structure

Complete synchronization of coupled Hindmarsh-Rose (HR) neurons with a ring structure is studied. The criterion for complete synchronization of coupled neurons with the ring structure is obtained through the stability analysis of the linearized synchronization error system. Numerical simulation is given to test the criterion for a system with three coupled HR neurons.     

Scaling of the flow field in a combustion chamber with agas——gas injector

The scaling of the flowfield in a gas--gas combustion chamber is investigated theoretically, numerically and experimentally. To obtain the scaling criterion of the gas--gas combustion flowfield, formulation analysis of the three-dimensional (3D) Navier--Stokes equations for a gaseous multi-component mixing reaction flow is conducted and dimensional analysis on the gas--gas combustion phenomena is also carried out. The criterion implies that the size and the pressure of the gas--gas combustion chamber can be changed. Based on the criterion, multi-element injector chambers with different geometric sizes and at different chamber pressures ranging from 3~MPa to 20~MPa are numerically simulated. A multi-element injector chamber is designed and hot-fire tested at five chamber pressures from 1.64~MPa to 3.68~MPa. Wall temperature measurements are used to understand the similarity of combustion flowfields in the tests. The results have verified the similarities between combustion flowfields under different chamber pressures and geometries, with the criterion applied.     

A new type of conserved quantity of Mei symmetry for the motion of mechanico electrical coupling dynamical systems

We obtain a new type of conserved quantity of Mei symmetry for the motion of mechanico-electrical coupling dynamical systems under the infinitesimal transformations. A criterion of Mei symmetry for the mechanico-electrical coupling dynamical systems is given. Simultaneously, the condition of existence of the new conserved quantity of Mei symmetry for mechanico-electrical coupling dynamical systems is obtained. Finally, an example is given to illustrate the application of the results.     

A Criterion for Stability of Synchronization and Application to Coupled Chua＇s Systems

We investigate synchronization in an array network of nearest-neighbor coupled chaotic oscillators. By using of the Lyapunov stability theory and matrix theory, a criterion for stability of complete synchronization is deduced. Meanwhile, an estimate of the critical coupling strength is obtained to ensure achieving chaos synchronization. As an example application, a model of coupled Chua＇s circuits with linearly bidirectional coupling is studied to verify the validity of the criterion.     

Fracture Criterion for Fracture Mechanics of Magnets

The applicability and limitation of some fracture criteria in the fracture mechanics of magnets are studied. It is shown that the magnetic field intensity factor can be used as a fracture criterion when the crack in a magnet is only affected by a magnetic field. For some magnetostrictive materials in which the components of magnetostriction strain do not satisfy the compatibility equation of deformation, the stress intensity factor can no longer be effectively applicable as a fracture criterion when the crack in a magnet is affected by a magnetic field and mechanical loads simultaneously.     

Separability criteria based on Heisenberg–Weyl representation of density matrices

Separability is an important problem in theory of quantum entanglement. By using the Bloch representation of quantum states in terms of the Heisenberg–Weyl observable basis, we present a new separability criterion for bipartite quantum systems. It is shown that this criterion can be better than the previous ones in detecting entanglement. The results are generalized to multipartite quantum states.     

Hamiltonians allowing wave equations

A general criterion of when a Hamiltonian system has a wave equation is set up, and all such Hamiltonian systems (and hence all wave equations) are found. It is shown that the correspondence is one-to-one.     

The radiation wave zone

The criterion for the formation of a radiation wave zone of a charge moving in an arbitrary way is discussed. The appearance of a wave zone is investigated in detail for synchrotron radiation and radiation from a charge moving along a hyperbola. Special attention is given to the ultrarelativistic case.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 3, pp.30–33, March, 1972.     

Rogue wave observation in a water wave tank

The conventional definition of rogue waves in the ocean is that their heights, from crest to trough, are more than about twice the significant wave height, which is the average wave height of the largest one-third of nearby waves. When modeling deep water waves using the nonlinear Schr?dinger equation, the most likely candidate satisfying this criterion is the so-called Peregrine solution. It is localized in both space and time, thus describing a unique wave event. Until now, experiments specifically designed for observation of breather states in the evolution of deep water waves have never been made in this double limit. In the present work, we present the first experimental results with observations of the Peregrine soliton in a water wave tank.     

Criterion for the accuracy of wave functions of asymmetric atomic and molecular systems

From the condition for invariance of the energy under rotations of the Jacobi coordinates, a relationship is obtained that relates the expected values of combinations of degrees of interparticle separations in quantum-mechanical systems. This relationship, which is satisfied for atoms and molecules with like particles identically, because of the permutational symmetry, is an extremely sensitive criterion for the accuracy of the wave functions of asymmetric systems, consisting of unlike particles and having no permutational symmetry. The application of this criterion is illustrated for the example of the asymmetric ⁴Heμ^?e^? mesoatom.     

Antenna pattern for four gravitational wave antennas

Summary The antenna pattern is analysed for four widely spaced cryogenic gravitational wave antennas which are expected to begin operating in coincidence during 1987. Using reasonable assumptions for senstivity, the four-antenna pattern is shown to give between 50% and 80% sky coverage for circularly polarized radiation under the minimum-detection criterion of two-way coincidence. One-hundred percent sky coverage can be achieved if one antenna is reoriented, but this is at the expense of reduced probability for 3-way coincidences.     

Correction of aberration for a high-resolution electron hologram by means of the amplitude contrast criterion of image wave

In order to further improve the resolution for a high-resolution electron hologram, the aberration working on the hologram must be corrected. Since it is rather difficult to precisely control aberration coefficients in the experimental stage, we proposed an amplitude contrast D criterion of imaging wave to determine the working aberration from the hologram itself. In the determination or correction of the aberration, we assume a symmetrical aberration function is parameterized only by a spherical aberration coefficient and a defocus value. First, D is calculated from a holographically reconstructed imaging wave of YBa(2)Cu(3)O(7-x) for each combination of these parameters. The working aberration on the imaging wave is determined from the combination of the parameters by noting the maximum or minimum D of the imaging wave at some specifically chosen thickness regions. The theoretical validity for the D criterion is then proved with three-beam dynamical diffraction formula. Finally, the 'experimental' examination for the D criterion is successfully performed on the reconstructed image wave for the Sigma=9 interface structure of a wedge-shaped silicon sample.     

Stability analysis of second- and fourth-order finite-difference modelling of wave propagation in orthotropic media

The stability of the finite-difference approximation of elastic wave propagation in orthotropic homogeneous media in the three-dimensional case is discussed. The model applies second- and fourth-order finite-difference approaches with staggered grid and stress-free boundary conditions in the space domain and second-order finite-difference approach in the time domain. The numerical integration of the wave equation by central differences is conditionally stable and the corresponding stability criterion for the time domain discretisation has been deduced as a function of the material properties and the geometrical discretization. The problem is discussed by applying the method of VonNeumann. Solutions and the calculation of the critical time steps is presented for orthotropic material in both the second- and fourth-order case. The criterion is verified for the special case of isotropy and results in the well-known formula from the literature. In the case of orthotropy the method was verified by long time simulations and by calculating the total energy of the system.     

On the criterion for effectiveness of wave linear transformation in a smoothly inhomogeneous medium and of nonadiabatic transitions during atomic collisions

A universal criterion for effectiveness of linear transformation of waves with locally close characteristic exponents in smoothly inhomogeneous media is obtained. The same criterion is applicable for estimating the effectiveness of nonadiabatic transitions in slow atomic collisions. The formalism developed for an analysis of the linear interaction of waves is based of the WKB asymptotic form of the solution of a scalar nth order ordinary differential equation. The obtained criterion can be applied in any practical problem for drawing a conclusion about the effectiveness of the linear interaction of modes if only the characteristic equation of waves in a homogeneous medium and the coefficients of the initial differential equation are known. In this case, the solution of the problem is reduced to elementary arithmetic calculations.     

A phase regulated back wave propagation technique for geoacoustic inversion

An inversion method based on the concept of back wave propagation (BWP) is described in this paper for estimation of geoacoustic parameters from acoustic field data. A phase-regulation technique is introduced to increase the sensitivity of the method for geoacoustic model parameters having low sensitivity. The case of data consisting of signal plus additive noise is also addressed. It is shown theoretically that the sensitivity can be increased by a factor alpha using the phase regulation procedure, and that the spatial resolution of signal energy that is concentrated by BWP at the known source position is increased when a increases. This result suggests an effective criterion for use in the inversion, based on the spatial distribution of signal energy around the true source location. The basis for the criterion is the spatial variance of the back-propagated pressure field in a window around the known source location. A multistep search process is proposed to avoid using a complicated multidimensional search process. Inversion results from both simulations and experimental data are given. The real data were taken from the Pacific Shelf experiment carried out in shallow water off the West Coast of Vancouver Island in the Northeast Pacific Ocean.     

Spin-density wave in a Kondo lattice

An Anderson model with N-fold degeneracy in the Kondo regime is considered. It is presumed that the electron-electron correlations in the system of f electrons have their maximum strength. A criterion for instability against the formation of a weakly antiferromagnetic phase superposed on the Kondo state is obtained by the auxiliary-boson method using the 1/N expansion. An effective interaction leading to the formation of magnetic ordering appears because of the spin fluctuations in the system of localized electrons. The phase diagram of the system is constructed. Zh. éksp. Teor. Fiz. 111, 600–614 (February 1997)