谷氨酸钠从其水溶液中的周期结晶现象

早在本世纪初物理化学家们就已观察到，某些物质从其熔融态或溶液中结晶出来时，在某些条件下可形成周期性的宏观结晶条纹［1，2］，这就是周期结晶现象，由于这种现象和晶体生长、材料物性以及成矿过程等重要问题紧密相关，很早就引起了人们的重视．近年来有关非平衡非线性系统中自发产生各种时空有序现象（自组织现象）的各种理论（如耗散结构理论）［3］的兴起，重新引起了人们对这类现象的兴趣．八十年代，Iwamoto等先后报道了甲基苄基氨基甲酸酯（MethylMesitylcarbamate）从氯仿溶液［4］和抗坏血酸（AscorbicAcid）从甲醇溶液［5］…     

Periodical states and marching groups in a closed owari

Owari is an old African game that consists of cyclically ordered pits that are filled with pebbles. In a sowing move all the pebbles are taken out of one pit and distributed one by one in subsequent pits. Repeated sowing will give rise to recurrent states of the owari. Bouchet studied such periodical states in an idealised setup, where there are infinitely many pits. We characterise periodical states in owaris with finitely many pits. Our result implies Bouchet's result.     

A NEW FAMILY OF BINARY SEQUENCES WITH OPTIMAL AUTOCORRELATION VALUES AND NICE PSEUDO-RANDOM PROPERTIES

In this paper we present a series of binary sequences which is a generalization of GMW sequences constructed by Scholtz and Welch. Our sequences have optimal autocorrelation values as m -sequences, and nice pseudo-random property. The number of such sequences is counted and the linear span of such sequences is evaluated.     

Real time task scheduling allowing fuzzy due dates

The paper deals with periodical task scheduling. The tasks are described by fuzzy due dates and fuzzy execution times. The goal of scheduling is to find an optimal assignment of priorities such that the satisfaction associated with due dates and execution times be minimized. The paper shows how the rules associated with task priorities improve the optimal assignment search.     

Controllability of an underactuated spacecraft with one thruster under disturbance

For an underactuated spacecraft using only one thruster,the attitude controllability with respect to the orbit frame is studied in the presence of periodical oscillation disturbance,which provides a preconditional guide on designing control law for underactuated attitude control system.Firstly,attitude dynamic model was established for an underactuated spacecraft,and attitude motion was described using the special orthogonal group(SO(3)).Secondly,Liouville theorem was used to confirm that the flow generated by the drift vector of the underactuated attitude control system is volume-preserving.Furthermore,according to Poincare’’s recurrence theorem,we draw conclusions that this drift field is weakly positively poisson stable(WPPS).Thirdly,the sufficient and necessary condition of controllability was obtained on the basis of lie algebra rank condition(LARC).Finally,the controllable conditions were analyzed and simulated in different cases of inertia matrix with the installed position of thruster.     

Ohmic quality of resonators shaped by corrugated guide sections at frequencies near bragg stop bands

The effect of ohmic loss decrease in corrugated waveguide is studied for the case of period, equal to half of longitudinal wave length (so called π-type oscillations). As demonstrated, in periodical guide there are π-type waves with ohmic quality growing approximatelly as a cube of guide radius, which looks very attractive for different applications.     

弱电场驱动下高分子链在周期管道内输运的模拟研究

采用Langevin动力学方法模拟研究了弱电场驱动下高分子链在无限长周期管道中的输运过程. 管道由长度相等的α和β两部分周期排列而成, 其中高分子链与α管道间存在相互吸引作用, 而与β管道间存在纯排斥作用. 模拟结果表明, 高分子链在输运过程中存在明显的受限阶段, 其逃离受限的方式与管道宽度有关且满足不同的规律. 对于窄管道, 高分子链在输运过程中呈直线伸展构型且运动具有“蛇爬行”特征. 高分子链逃离受限过程伴随着整条链的运动, 从而导致迁移率随高分子链长呈周期变化, 而且在迁移率极值位置, 高分子链投影长度与管道半周期之间存在简单的整数倍关系. 对于宽管道, 高分子链在输运过程中出现弯折构型且运动具有“蠕虫运动”特征. 当链长比较长时, 高分子链可通过链前端部分的伸长逃离受限, 从而导致迁移率与高分子链长度无关. 模拟结果可能有助于利用周期管道对不同长度的高分子链进行分离及可控输运.     

Transmission characteristics of various bent periodic dielectric waveguides

The transmission characteristics of various bent periodical dielectric waveguides (PDWGs) are analyzed by the finite-difference time-domain (FDTD) method in this work. The bending structures include a conventional 90° abrupt bend, a 90° transitional bend, and 90° circular arcs with different quantized radii of curvatures. The simulation results can make us to design a suitable bent PDWG in the photonic circuits.     

具有周期维护最小化时间表长的两台平行机调度问题(英文)

本文讨论了具有周期维护的两台平行机调度问题,目标函数为最小化时间表长.设T为维护周期,t为每次对机器维护需要的时间,当t≤T/3时,本文证明了对于该问题由LPT算法得到的最坏误差界为2.     

Hopf bifurcation of a bacteria-immunity system with delayed quorum sensing

On the basis of Zhang’s model (see [P. Fergola, J. Zhang, M. Cerasuolo, Z.E. Ma, On the influence of quorum sensing in the competition between bacteria and immune system of invertebrates, in: Collective Dynamic: Topics on Competition and Cooperation in the Biosciences: A Selection of Papers in the Proceedings of the BIOCOMP2007 International Conference, AIP Conference Proceedings, vol. 1028, 2008, pp. 215-232] for more details), we formulate a bacteria-immunity model to describe the competition between bacteria and immune cells with bacterial quorum sensing mechanism. A time delay is introduced to characterize the time in which bacteria receive signal molecules and then combat with immune cells. Subsequently, the length of delay which preserves the stability of the positive equilibrium is estimated and Hopf bifurcation occurs when time delay crosses through a critical value are researched. Further, by using the normal form theory and center manifold theory, the explicit formulaes are calculated which determine the stability, the direction and the period of bifurcating periodical solutions. Finally, numerical simulations are employed to verify the mathematical conclusions.