State diagrams of arabinoxylan-water binaries

Since Arabinoxylans are natural polysaccharides that seem promising candidates as cryostabilizers, the state diagram (i.e. the representation in the temperature-composition plan of the macroscopic phases) of their aqueous solutions seemed worth determining.

Two lots of purified water extractable arabinoxylans (WEA) of different molecular mass (56 and 410 kDa labeled as LMW-AX and HMW-AX, respectively) were used to prepare aqueous solutions of various composition. These were cooled below their freezing point and annealed for 2 h at a suitable temperature before a DSC 5°C min⁻¹ heating run aimed at determining their primary glass transition temperature, T_g′, and the onset of ice fusion. Once the corresponding composition, C_g′, was assessed, the main curves of the corresponding state diagram were drawn.

As expected, the T_g′ value drawn for HMW-AX was higher (−17°C) than for LMW-AX (−35°C). The C_g′ was instead found close to 75% w/w for both HMW-AX and LMW-AX. The fictitiousness of this coincidence could be easily recognized by expressing the solute concentration in molar fraction, X: it was then possible to verify that, as expected, X_g′ for LMW-AX was one order of magnitude larger than for HLW-AX.     

可逆变流器的OPWM控制

提出一种适用于单片机实现的可逆变流器谐波优化控制方法 .它使变流器可以工作于较低的载波频率而具有近于零的低次谐波 ,因而特别适用于 GTO大功率变流器 .论述了优化开关角的求解方法 ,分析了优化开关角的特点 .仿真结果表明了优化开关角解的正确性     

Λ型原子与单模光场的非共振作用制备四光子相干态

根据简并Λ型三能级原子与单模光场的改进型有效哈密顿量 ,通过矩阵形式法推导出原子光场系统的波函数 ,提出利用简并Λ型三能级原子与单模光场的远离共振相互作用制备四光子相干态的有效方案。并且证明按照同样的方法不能制备出四成分以上的相干叠加态 ,即当在腔中注入的第三个原子的速度与第二个原子的速度相等时 ,腔场将保持这种四光子相干叠加态不变     

Resonant two-photon ionization with high-order continuum states

In this paper,the resonant two-photon ionization of atoms with high-order con-tinuum state is studied.It's found that the C-C coupling among the continuum states enhancesthe two-level atomic Rabi oscillation,and the direct transition from the intermidiate excitedstate to the continuum weakens the Rabi oscillation.Therefore the photoelectron energy spec-tra and the population are changed.     

A new formulation of some discrete-time stochastic-parameter state estimation problems

Linear unbiased full-order state estimation problem for discrete-time models with stochastic parameters and additive finite energy type disturbance signals is reformulated in terms of linear matrix inequalities. Two estimation problems that are considered are the design for mean-square bounded estimation error and the design for the mean-square stochastic version of the suboptimal H_∞ estimator. These two designs are shown to apply to both the estimation with random sensor delay and estimation under observation uncertainty.     

Semilinear elliptic problems near resonance with a nonprincipal eigenvalue

We consider the Dirichlet problem for the equation −Δu=λu±f(x,u)+h(x) in a bounded domain, where f has a sublinear growth and h∈L². We find suitable conditions on f and h in order to have at least two solutions for λ near to an eigenvalue of −Δ. A typical example to which our results apply is when f(x,u) behaves at infinity like a(x)|u|^q−2u, with M>a(x)>δ>0, and 1<q<2.     

Optimality conditions for state constrained nonlinear control problems

The problem of optimal control of nonlinear control and state constrained control problems, where the state constraint may involve differential operators and the cost functionals may be nonsmooth, is studied. For this class of problems, necessary optimality conditions using techniques from infinite dimensional optimization theory adapted to the framework of control problems are derived. It is shown that the underlying structure admits a considerable relaxation of the classical constraint qualifications. The theory then is applied to examples of various nonlinear elliptic equations and state constraints.     

Novel Rat-race Hybrid Coupler for RF Front-end Module

In this paper, a novel compact rat-race hybrid coupler incorporating an improved beeline compact microstrip resonant cell(IB-CMRC) is presented firstly. The size of the coupler is reduced by 46.5% than conventional one due to IB-CMRC’s excellent slow-wave effect. The novel coupler possesses strong ability of high-order harmonic suppression (above 30 dB) in addition. The measured insertion loss is comparable to that of a conventional microstrip hybrid coupler. Great potential applications of this IB-CMRC can be explored in MICs and MMICs to reduce the circuits size, suppress harmonics and improve the overall performance of the RF front-end module.     

硅基双势垒金属-绝缘层-金属-绝缘层-半导体隧道发光结

讨论了硅基双势垒金属－绝缘层－金属－绝缘层－半导体（MIMIS）隧道发光结的结构、制备方法及发光特性。所制备的样品最大发光亮度达到1．9cd/m^2、光谱的峰值波长移到了蓝绿光区，表明双势垒MIMIS隧道发光结的性能优于单势垒金属－绝缘层－半导体（MIS）隧道发光结。利用量子力学的共振隧穿效应对它作了较好的解释。     

Asymptotic Analysis of State Constrained Semilinear Optimal Control Problems

The asymptotic behavior of state-constrained semilinear optimal control problems for distributed-parameter systems with variable compact control zones is investigated. We derive conditions under which the limiting problems can be made explicit. We gratefully acknowledge the support of the DAAD. The paper was prepared during the visit of the first author at the Institute of Applied Mathematics II, University Erlangen-Nuremberg in 2003.