基于数字非线性锁相环的相干态相位估计

基于量子理论获取相位参数的导航机制,理论上可以突破经典物理极限对导航精度的限制.利用量子零拍探测对相干态光场相位进行测量时,通常需要相位与之正交的本振光才能使测量精度达到量子标准极限.由于导航信号相位的高非线性特点,想要利用传统的线性锁相环获取完全满足条件的本振光具有一定的难度.为此,本文设计了一种基于容积准则的非线性锁相环,实现了在非正交本振光的条件下对相干态相位进行精确测量的功能.首先,利用相干态的Wigner函数推导了其相位在量子零拍探测的输出结果,设计了量子相位估计的非线性数字锁相环框架.然后基于正交单纯形容积准则设计了非线性滤波算法实现锁相环功能,该锁相环通过对本振相位进行多次状态更新,最终实现非线性迭代估计.实验结果表明,本文方法突破了本振光相位需与相干态相位正交的局限性,避免了传统量子锁相环方法引入的线性化误差,实现了对相干态相位的准确、稳定估计.     

Influence of Co amount on the efficiency of energy absorption of Fe-Co ferrite nanoparticles

We present the chemical synthesis, structural characterization and efficiency of AC field energy absorption of Fe-Co ferrite particles sized between 35 and 100 nm and containing different cobalt amounts up to 3 wt%. Dynamic magnetic measurements in an AC field with frequency of 430 Hz and amplitude of up to 1200 Oe were performed for both solid and liquid dispersions of obtained particles. The energy absorption per one field cycle in function of the field amplitude and Co content was always bigger in liquid systems, under the same conditions, than in solid systems. The obtained results are of significance for the technology of low-frequency ferromagnetic hyperthermia of tumors.     

SOA-based loop mirror for tunable pulse-width generation

We propose and experimentally demonstrate a system for the generation of pulses of tunable pulse-width as those required in high spectral efficiency optically routed networks. Pulse narrowing of 500 ps pulses by 90% is accomplished through a SOA based non-linear loop mirror. Optical switching through the SOA loop mirror is used to shape and carve these large pulses (e.g., 500 ps) generated by non-expensive low-frequency optoelectronic components to narrow pulses (e.g., 50 ps). We also calculate the minimum loop size and optimum repetition rate of the original pulse train for the generation of the shorter pulse-width pulse train.     

Multi-component C-KdV Hierarchy of Soliton Equations and Its Multi-component Integrable Coupling System

A new simple loop algebra G M is constructed, which is devoted to establishing an isospectral problem. By making use of Tu scheme, the multi-component C-KdV hierarchy is obtained. Further, an expanding loop algebra FM of the loop algebra G M is presented. Based on FM , the multi-component integrable coupling system of the multi-component C-KdV hierarchy is worked out. The method can be used to other nonlinear evolution equations hierarchy.     

New Simple Method for Obtaining Integrable Hierarchies of Soliton Equations with Multicomponent Potential Functions

A new simple method for obtaining integrable hierarchies of soliton equations is proposed. First of all, a new loop algebra is constructed, whose commutation operation is clear as that in loop algebra . Second, by making use of the Tu scheme, many of integrable hierarchies with multicomponent potential functions can be produced. As a specific application of our method, a multicomponent AKNS hierarchy is obtained. Finally, an expanding loop algebra of the loop algebra is constructed. Taking advantage of above, a type of integrable coupling system of the multicomponent AKNS hierarchy is worked out.     

Incidence properties of cosets in loops

We study incidence properties among cosets of infinite loops, with emphasis on well‐structured varieties such as antiautomorphic loops and Bol loops. While cosets in groups are either disjoint or identical, we find that the incidence structure in general loops can be much richer. Every symmetric design, for example, can be realized as a canonical collection of cosets of a infinite loop. We show that in the variety of antiautomorphic loops the poset formed by set inclusion among intersections of left cosets is isomorphic to that formed by right cosets. We present an algorithm that, given a infinite Bol loop S, can in some cases determine whether |S| divides |Q| for all infinite Bol loops Q with S?Q, and even whether there is a selection of left cosets of S that partitions Q. This method results in a positive confirmation of Lagrange's Theorem for Bol loops for a few new cases of subloops. Finally, we show that in a left automorphic Moufang loop Q (in particular, in a commutative Moufang loop Q), two left cosets of S?Qare either disjoint or they intersect in a set whose cardinality equals that of some subloop of S.     

The road towards the international linear collider: Higgs,top/quantum chromodynamics,loops

The international linear e ⁺ e ⁻ collider (ILC) could go into operation in the second half of the upcoming decade. Experimental analyses and theory calculations for the physics at the ILC are currently performed. We review recent progress, as presented at the LCWS06 in Bangalore, India, in the fields of Higgs boson physics and top/QCD. Also the area of loop calculations, necessary to achieve the required theory precision, is included.      

受限亚音速气流中倒置悬臂壁板静气弹稳定性的理论及实验研究

板壳结构在航空航天、高速列车、能量采集等诸多工程领域已经得到了广泛应用.将悬臂壁板倒置于轴向气流中并在壁板周围流场中设置刚性壁面可有效地调控壁板的失稳速度,是俘能器优化设计的重要措施之一.但针对刚性壁面作用下亚音速气流中倒置悬臂壁板的失稳机制仍需要开展深入研究.本文以受限亚音速气流中倒置的二维悬臂壁板为对象,以理论分析及风洞实验为手段,研究了单侧刚性壁面效应对倒置悬臂壁板静态失稳特性的影响规律.在理论分析中,首先应用镜像函数法来处理壁面约束条件,基于算子理论研究获得了以Possio积分方程为表征的壁板气动力,壁面效应实际表征为一包含移位Tricomi算子的复合算子;然后将壁板失稳方程的求解问题转化为定区间上的函数逼近问题;最后,依据Wererstrass定理并利用最小二乘法求解该最优函数,以获得系统的失稳临界参数.在试验研究中依据压杆稳定原理设计了壁板静态失稳的测试方法并完成了风洞实验.理论分析结果表明,壁板会发生发散(静气动弹性)失稳,临界动压随壁板与壁面间距的增加而增大并最终趋于稳定(无壁面情况);通过理论与风洞实验结果的对比分析,验证了本文气动力及理论分析的适用性及准确性.针对倒...     

An Interpenetrated Framework Material with Hysteretic CO2 Uptake

A new, twofold interpenetrated metal–organic framework (MOF) material has been synthesized that demonstrates dramatic steps in the adsorption and hysteresis in the desorption of CO₂. Measurement of the structure by powder X‐ray diffraction (PXRD) and pair distribution function (PDF) analysis indicates that structural changes upon CO₂ sorption most likely involve the interpenetrated frameworks moving with respect to each other.     

Domain reorientation dynamics of sol–gel derived strontium doped PLZT (8/65/35)

Polycrystalline samples of PLSZT with the composition Pb_0.92−x La_0.08Sr _x (Zr_0.65Ti_0.35)O₃ (where x = 0, 0.02, 0.04, 0.06, 0.08, and 0.10) have been synthesized by sol–gel technique. DTA analysis confirms that all the organic constituents get decomposed and final PLZT is formed at 545 °C. The XRD analysis suggests the formation of single rhombohedral perovskite phase with decreasing unit cell parameter. Crystallite size calculated, using Scherrer’s equation, was found to decrease with Sr doping due to smaller ionic radii of Sr than Pb. Compact uniform grain distribution was observed from SEM micrographs. The ferroelectric to paraelectric phase transition temperature, maximum dielectric constant and remanent polarization (P _r) were found to decrease with Sr doping along with increasing diffuse nature of phase transformation. Detailed domain reorientation dynamics study suggests that Sr doping increases the percentage backswitching and decreases the normalized coercivity by decreasing the viscous nature of composition.