Mode shift and stability control of a current mode controlled buck-boost converter operating in discontinuous conduction mode with ramp compensation

By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagrazn, Lyapunov exponent spectrum, time- domain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region.

Dynamical analysis and experimental verification of valley current controlled buck converter

The dynamical behaviours of valley current controlled buck converter are studied by establishing its corresponding discrete iterative map model in this paper. Time-domain waveforms and phase portraits of valley current controlled buck converter are obtained by Runge-Kutta algorithm through a piecewise smooth switching model. The research results indicate that the valley current controlled buck converter exhibits rich nonlinear phenomena, and it has routes to chaos through period-doubling bifurcation and border-collision bifurcation in a wide parameter range. Interesting inverse nonlinear behaviours compared with peak current controlled buck converter are observed in the valley current controlled buck converter. Analysis and simulation results are verified by experimental results.

Physicochemical and isomerization property of Pt/SAPO-11 catalysts promoted by rare earths

Monometallic catalyst Pt/SAPO-11 was prepared by impregnation method.Bimetallic catalysts LaPt/SAPO-11 or CePt/SAPO-11 was prepared by sequential impregnation method.The catalysts were characterized by X-ray diffraction(XRD),nitrogen adsorption,temperature-programmed desorption of ammonia(NH3-TPD),and Fourier transform infrared spectroscopy(FT-IR) techniques.The results showed that with the addition of rare earths the BET surface areas,pore volume,the amount of Bronsted acid and the total acidity of catalys...

EFFECTS OF DIFFERENT FUNCTIONAL GROUP-CONTAINING ORGANICS ON MORPHOLOGY-CONTROLLED SYNTHESIS OF SILVER NANOPARTICLES AT ROOM TEMPERATURE

Silver nanoparticles with average particles sizes ranging from 2 to 131nm were manipulatively synthesized starting from silver nitrate using different functional group-containing organic modifiers at room temperature. The effects of the organic modifiers on the morphology of the resulting silver nanoparticles were strongly dependent on the intrinsic properties of the functional groups and the reducibility of the reductant. Numerous ether bonds （-0-）present in polyethylene glycol and Tween-80 were beneficial to the formation of silver nanoparticles with particle sizes of several nanometers in a narrow size distribution in both weak and strong reducing environments. Cetyltrimethylammonium bromide induced the formation of nanosized silver triangle plates in a weak reducing environment. The crystal growth of the silver nanoparticles with particle sizes of more than lOnm was postulated through an adhesion process of small-sized particles followed by a subsequent coalescence process under the present reaction conditions.

A generalization of exotic options pricing formulae

Exotic options, or “path-dependent” options are options whose payoff depends on the behavior of the price of the underlying between 0 and the maturity, rather than merely on the final price of the underlying, such as compound options, reset options and so on. In this paper, a generalization of the Geske formula for compound call options is obtained in the case of time-dependent volatility and time-dependent interest rate by applying martingale methods and the change of numeraire or the change of probability measure. An analytic formula for the reset call options with predetermined dates is also derived in the case by using the same approach. In contrast to partial differential equation (PDE) approach, our approach is simpler.

THE P-COTORSION DIMENSIONS OF MODULES AND RINGS

Let R be a ring. We define a dimension, called P-cotorsion dimension, for modules and rings. The aim of this article is to investigate P-cotorsion dimensions of modules and rings and the relations between P-cotorsion dimension and other homological dimensions. This dimension has nice properties when the ring in consideration is generalized morphic.

Transition of super-hydrophobic states of droplet on rough surface

Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study the effect ofb on the wettability of the rough surface, the effects of apparent contact angle （CA） and sliding angle （a） of the droplet on the rough surface were measured with the contact angle meter. The results show that the experimental values of CA well agree with the classical wetting theory and a decreases with the increase of b. Two drop shapes exist on the samples＇ surface, corresponding to the Cassie state and the Wenzel state respectively. The contact state in which a drop would settle depends typically on the size of b. On the role of gravitation, the irreversible transition of a drop from Cassie state to Wenzel state should occur at a certain space of the square pillars. Since the transition has implications on the application of super-hydrophobic rough surfaces, theoretically, the prediction of wetting state transition on square pillar array micro-structured surfaces provides an intuitionistic guidance for the design of steady superhydrophobic surfaces.

Complexity analysis of interior-point algorithm based on a new kernel function for semidefinite optimization

Interior-point methods （IPMs） for linear optimization （LO） and semidefinite optimization （SDO） have become a hot area in mathematical programming in the last decades. In this paper, a new kernel function with simple algebraic expression is proposed. Based on this kernel function, a primal-dual interior-point methods （IPMs） for semidefinite optimization （SDO） is designed. And the iteration complexity of the algorithm as O（n^3/4 log n/ε） with large-updates is established. The resulting bound is better than the classical kernel function, with its iteration complexity O（n log n/ε） in large-updates case.

NUMERICAL ANALYSIS AND EXPERI-MENT OF UNSTEADY THERMAL FIELD OF ROTOR PLATE FOR EDDY CURRENT RETARDER

The physical model based on heat transfer theory and virtual boundary method for analyzing unsteady thermal field of rotor plate for eddy current retarder used in automobile is established and boundary conditions are also defined. The finite element governing equation is derived by Galerkin method. The time differential item is discrete based on Galerkin format that is stable at any condition. And a new style of varying time step method is used in iteration process. The thermal field on the rotor plate at the radial and axle directions is analyzed and varying temperature at appointed points on two side-surfaces is measured. The testing and analytical data are uniform approximately. Finite element method can be used for estimating thermal field of the rotor plate at initial design stage of eddy current retarder.

Symmetrical dynamics of peak current-mode and valley current-mode controlled switching dc-dc converters with ramp compensation

The discrete iterative map models of peak current-mode （PCM） and valley current-mode （VCM） controlled buck converters, boost converters, and buck-boost converters with ramp compensation are established and their dynamical behaviours are investigated by using the operation region, parameter space map, bifurcation diagram, and Lyapunov exponent spectrum. The research results indicate that ramp compensation extends the stable operation range of the PCM controlled switching dc-dc converter to D 〉 0.5 and that of the VCM controlled switching dc-dc converter to D 〈 0.5. Compared with PCM controlled switching dc-dc converters with ramp compensation, VCM controlled switching dc-dc converters with ramp compensation exhibit interesting symmetrical dynamics. Experimental results are given to verify the analysis results in this paper.

Non-Gaussianity and decoherence of generalized photon-added coherent state as a Hermite-excited coherent state

Generalized photon-added coherent state （GPACS） is creation and annihilation operations on the coherent state. obtained by repeatedly acting the combination of Bose It is found that GPACS can be regarded as a Hermiteexcited coherent state due to its normalization factor related to a Hermite polynomial. In addition, we adopt the Hilbert-Schmidt distance to quantify the non-Gaussian character of GPACS and discuss the decoherence of GPACS in dissipative channel by studying the loss of nonclassicality in reference of the negativity of Wigner function.

Application of Bipartite Entangled States to Quantum Mechanical Version of Complex Wavelet Transforms

We introduce the bipartite entangled states to present a quantum mechanical version of complex wavelet transform. Using the technique of integral within an ordered product of operators we show that the complex wavelet transform can be studied in terms of various quantum state vectors in two-mode Fock space. In this way the creterion for mother wavelet can be examined quantum-mechanically and therefore more deeply.

Existence and asymptotic estimates of periodic solutions of El Nio mechanism of atmospheric physics

This paper is devoted to studying the El Nino mechanism of atmospheric physics. The existence and asymptotic estimates of periodic solutions for its model are obtained by employing the technique of upper and lower solution, and using the continuation theorem of coincidence degree theory.

PREPRARATION OF CoPcS/TiO_2/BEADS AND THEIR PHOTOCATALYTIC REACTIVITY FOR PHOTODEGRADATION OF VEGETABLE OIL FLOATING ON WATER

The paper introduces the preparation of floating TiO2/beads photocalyst attached to the hollow glass micro-beads surface by sol-gel technique using tetrabutyl titanate as material and the preparation of floating CoPcS/TiO2/beads by dip-coatig technique. The optimal factor of degradation of vegetable oil floating on water using CoPcS/TiO2/beads was studied. The result showed that the removal rate of vegetable oil floating on water can highly reach 90% at the optimal condition （acidity or neutrality, 375W medium-pressure mercury vapour lamp, illumination 2h-3h, lg CoPcS/TiO2/beads）. The photocatalytic removal efficiency causing by CoPcS/TiO2/beads was increased rapidly by adding a trace amount of H2O2.

Fast-Scale and Slow-Scale Subharmonic Oscillation of Valley Current-Mode Controlled Buck Converter

A valley current-mode （VCM） controfled buck converter with current source load （CSI） has complex phenomena of fast-scale and slow-scale subharmonic oscillations. The piecewise smooth switching model of the VCM controlled buck converter with CSI is established. It is found that attractive regions of fast-scale and slow-scale subharmonic oscillations exist in the bifurcation diagram, and two tori exist in the corresponding Poincare mapping. The research results by time-domain simulation indicate that U-type subharmonic oscillation （SO） constituted by SO and frequency-reduced subharmonic oscillation （FSO） exists in inductor current, and sine-type SO constituted by fast scale and low scale exists in output voltage respectively. Experimental results are given to verify the analysis and simulation results.

Wigner Function of Thermo-Invariant Coherent State

By using the thermal Winger operator of thermo-field dynamics in the coherent thermal state ｜ξ｜ representation and the technique of integration within an ordered product of operators, the Wigner function of the thermoinvariant coherent state ｜z,η） is derived. .The nonclassical properties of state [zη] is discussed based on the negativity of the Wigner function.

Microscopic characterization of semi-solid aluminium alloys

The microstructural evolution and element distribution of the Al-4Cu-Mg alloy during semi-solid compression were investigated, and the precipitate behavior and dislocation morphology were discussed. The experimental results show that the microstructure, the number of CuAl2 （θ phase） precipitates, and the dislocation density of the Al-4Cu-Mg alloy depend apparently on the process parameters. More segregation of Cu at the grain boundary happens with an increase of deformatinn temperature and a decrease of strain rate, leading to an increase in the number of θ phase. With an increase of height reduction, Cu segregation at the grain boundary decreases gradually. Moreover, unique dislocation morphologies including helical dislocations and dislocation loops appear at different process parameters and evolve to reduce the stored energy.

Acoustic band pinning in the phononic crystal plates of anti-symmetric structure

Acoustic bands are studied numerically for a Lamb wave propagating in an anti-symmetric structure of a one- dimensional periodic plate by using the method of supercell plane-wave expansion. The results show that all the bands are pinned in pairs at the Brillouin zone boundary as long as the anti-symmetry remains and acoustic band gaps （ABGs） only appear between certain bands. In order to reveal the relationship between the band pinning and the anti-symmetry, the method of eigenmode analysis is introduced to calculate the displacement fields of different plate structures. Further, the method of harmony response analysis is employed to calculate the reference spectra to verify the accuracy of numerical calculations of acoustic band map, and both the locations and widths of ABGs in the acoustic band map are in good agreement with those of the reference spectra. The investigations show that the pinning effect is very sensitive to the anti-symmetry of periodic plates, and by introducing different types of breakages, more ABGs or narrow pass bands will appear, which is meaningful in band gap engineering.

A Two-dimensional Coordination Polymer of Manganese(II) and Benzimidazole-5,6-dicarboxylate

A new two-dimensional （2D） manganese（II） coordination polymer {[Mn（bidc）（H2O）2]· 2H2O}n （H2bidc = benzimidazole-5,6-dicarboxylic acid） was synthesized, and characterized by X-ray crystallography and other measurements. The complex crystallizes in the orthorhombic system, space group Pbca with a = 7.0218（7）, b = 17.9701（18）, c = 19.0697（19）, V = 2406.3（4）3, Z = 8, Dc = 1.823 g/cm3, Mr = 330.14, F（000） = 1344, μ（MoKα） = 1.140 mm-1, S = 1.055, R = 0.0305 and wR = 0.1012 for 2130 observed reflections （I 2σ（I））. The title complex consists of a novel 2D network with a topology of short symbol （4.82）（4.82）.

Normally-Ordered Time Evolution Operator for Mass-Varying Harmonic Oscillator and Wigner Function of Squeezed Number State

For investigating dynamic evolution of a mass-varying harmonic oscillator we constitute a ket-bra integrationoperator in coherent state representation and then perform this integral by virtue of the technique of integration withinan ordered product of operators.The normally ordered time evolution operator is thus obtained.We then derive theWigner function of u(t)|n>,where |n> is a Fock state,which exhibits a generalized squeezing,the squeezing effect isrelated to the varying mass with time.