large Last Multiplier of Generalized Hamilton System

We study an application of the Jacobi last multiplier to a generalized Hamilton system. A partial differential equation on the last multiplier of the system is established. The last multiplier can be found by the equation. If the quantity of integrals of the system is sufficient, the solution of the system can be found by the last multiplier.     

Hamiltonian analysis of a Green-Schwarz sigma model on a supercoset target with Z4m grading

We perform a Hamiltonian analysis of the Green-Schwarz sigma model on a supercoset target with Z_4m grading. The fundamental Poisson brackets between the spatial component of the flat currents depending on a continuous parameter, which can be thought of as a first step in the complete calculation of the algebra of the transition matrices, are obtained. When m=1, our results are reduced to the results of the type IIB Green-Schwarz superstring on AdS₅ × S⁵ background obtained by Das, Melikyan and Sato.     

地方高校省级物理示范实验室建设的探索与实践

提出了示范实验室建设的思路与目标,阐述分层次模块化的实验教学体系,介绍了多样化的实验教学手段。经过3年的探索与实践,示范实验室建设成效显著、特色明显,取得了较为显著的成绩,有一定示范性和辐射作用。     

siPLS-LASSO的近红外特征波长选择及其应用

近红外技术广泛应用于食品、药品等生产过程和产品质量检测,具有样品无需预处理、成本低、无破坏性、测定速度快等优点。但是,全光谱数据维数高、冗余信息多,直接应用于建模会导致模型复杂性高、稳定性差等问题。siPLS是最常见的光谱数据降维方法,但是难以处理光谱数据的共线性问题。LASSO是一种相对新的数据降维方法,但在小样本应用中具有不稳定性。针对siPLS和LASSO在近红外光谱数据应用中存在的问题,提出了基于siPLS-LASSO的近红外特征波长选择方法,并将其应用于秸秆饲料蛋白固态发酵过程pH值监测。该方法首先采用siPLS算法,实现对光谱波长最佳联合子区间的优选;然后,对优选联合子区间使用LASSO算法进行特征波长选择,在此基础上建立PLS校正模型。同时,将siPLS-LASSO方法与其他传统特征波长选择方法进行了对比。结果表明：建立在siPLS-LASSO方法优选33个特征波长基础上的PLS模型预测结果更好,其预测方差(RMSEP)和相关系数(R_p)分别为0.071 1和0.980 8;所提siPLS-LASSO方法有效选取了特征波长,提高了模型预测性能。     

边界条件与一维高分子系统的稳定性

讨论了SSH模型在一维有限系统上的稳定性，提出了几种稳定边界的办法，并对边界条件的作用进行了分析讨论 关键词：     

Directed Motion of a Molecular Motor Based on the Four-State Model with Unequal Substeps

A periodic one-dimensional four-state hopping model is proposed. In the model, the substeps betweenarbitrary adjacent states are unequal, and an explicit solution of the master equation is first obtained for the probabilitydistribution as a function of the time and position for any initial distribution with all the transients included. Next, thetransient behaviors in the initial period of time and the characteristic time to reach the steady state for the molecularmotor are discussed. Finally, we compare the steady state results to experiments and illustrate qualitatively the kineticbehaviors of a molecular motor under external load F.     

基于共振型高灵敏度光声光谱技术探测痕量乙炔气体浓度

乙炔气体作为判断变压器运行状态的一种故障气体,其浓度的高低反映了变压器的运行状况,因此对其浓度的探测在变压器的维护中具有重要意义。为了准确探测变压器运行过程中产生的乙炔气体浓度,为变压器的维护提供技术参数,针对基于DFB激光器的共振型光声光谱技术痕量乙炔气体检测技术开展研究,对传统的光声光谱探测系统进行改进。根据光声光谱技术的理论可知,光声信号的强度与入射激光的功率成正比,所以在光声池的出射窗口采用一个平面反射镜将红外光再次反射到光声池中以增加入射光功率,增强光声信号强度,进一步提高了光声系统的探测灵敏度。通过一定浓度的乙炔气体在不同调制频率和不同调制深度下光声信号强度的变化,确定光声探测系统的最佳调制频率和最佳调制深度为767 Hz和0.3 mV。利用不同浓度乙炔气体对系统进行标定,然后采用最小二乘法对光声信号与气体浓度进行拟合,二者具有很好的线性度。通过Allan方差计算可知,系统在平均时间达到200 s时,能够达到最低探测极限浓度。实验表明,在一个大气压下,积分时间为10 ms时,改进后的共振型光声光谱探测系统对乙炔气体的最低探测极限浓度达到了0.3 μL·L-1。还将小波去噪技术引入到低浓度下乙炔气体的光声信号处理中,有效消除了低浓度气体光声信号中的噪声,提高了信噪比。设计的共振型光声光谱探测系统操作简单,最低探测浓度符合国标中对变压器维护过程中对乙炔气体的探测需求,在变压器维护领域具有广阔的应用前景。     

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators,due to their compactness and their convenient shape for tuning and coupling,are very attractive for low-β beam acceleration.In this paper,two types of cavities with different geometry have been numerically simulated the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz,β=0.06 beams then the relative electromagnetic parameters and geometric sizes have been compared.It is found that the second type,whose structural design is optimized with the conical stem and shaping drift-tube,can support the better accelerating performance.At the end of the paper,some structural deformation effects on frequency shifts and appropriate solutions have been discussed.     

微波消解-FAAS测定6种龙胆科植物花中微量元素的含量

选用硝酸和双氧水(5∶1)的混合消解液对样品进行微波消解,采用火焰原子吸收光谱法测定了云雾龙胆,管花秦艽,线性龙胆,黄管秦艽,麻花秦艽,蓝玉簪龙胆花这6种龙胆科植物花中的Ca、Mg、Cu、Fe、Mn、Zn6种微量元素的含量。该方法的加标回收率为96.53%—100.11%,相对标准偏差(RSD)小于3%,具有良好的准确度和精密度。研究结果显示,6种龙胆科植物花微量元素含量丰富,其中Mg、Ca、Fe的含量普遍较高,不同龙胆花中各元素的含量均有一定差异。本试验为这些龙胆花药材的合理药用及进一步的开发利用提供了可靠依据。     

石墨炉原子吸收光谱法测定不同地区秦艽花中铅和镉的含量

选用硝酸和高氯酸(4∶1)的混合消解液对样品进行微波消解,利用微波消解-石墨炉原子吸收光谱法测定不同地区秦艽花药材中铅、镉的含量。该方法铅、镉加标回收率分别为96.5%、94.0%,相对标准偏差(RSD)分别为2.7%、4.3%,具有良好的准确度和精密度。结果显示,不同地区的秦艽花中Pb的含量介于1.266—3.429mg·kg-1之间,Cd的含量均小于等于0.167mg·kg-1,不同地区秦艽花中Pb、Cd的含量均有一定差异。该测定结果为秦艽花药材的质量控制与开发利用提供可靠依据。