基于一致性算法的多智能体系统能控性性质

针对多智能体系统能控性方面的问题,采用图论及矩阵的方法研究了多智能体系统在对称拓扑和多领航者情况下的能控性,给出了拓扑结构为对称的系统能控性的几个性质。在领航者为多个时,指出了不对称的拓扑结构不再是多智能体系统能控性的必要条件。证明结果表明,图中连通枝的对称性（不是整个图对称）将导致系统的不能控以及在领航者是多个的情况下,如果领航者是来自任意的单元素单元,那么系统是不能控的。该结果为分析基于一致性算法的多智能体能控性提供了新的启示。     

H-Solid State NMR Studies of Tunneling Phenomena and Isotope Effects in Transition Metal Dihydrides

In many transition metal dihydrides and dihydrogen complexes the hydrogens are relatively weakly bound and exhibit a fairly high mobility, in particular with respect to their mutual exchange. Part of this high mobility is due to the exchange symmetry of the two hydrogens, which causes an energy splitting into even and odd spatial energy eigenfunctions, resulting in the typical coherent tunneling of a two-level system. Owing to the quantum mechanical symmetry selection principles the eigenfunctions are connected to the possible nuclear spin states of the system. If the tunneling frequency is in the proper frequency window it is thus possible to observe these tunneling transitions by NMR at very low temperatures, where no thermally induced exchange reactions overshadow the tunneling. The first part of this review gives an introduction into the interplay of chemical kinetics and tunneling phenomena in general, rotational tunneling of dihydrogen in a two-fold potential in particular and the Bell tunnel model, followed by a summary of solid state NMR techniques for the observation of these tunnel processes. Then a discussion of the effects of these processes on the ²H NMR line shape is given. The second part of the review reports results of a ²H-solid state NMR spectroscopy and T₁ relaxatiometry study of trans-[Ru(D₂)Cl(PPh₂CH₂CH₂PPh₂)₂]PF₆, in the temperature regime from 5.4 to 320 K. In the Ru-D₂ sample coherent tunneling and incoherent exchange processes on the time scale of the quadrupolar interaction are observed. From the spectra and T₁-data the height of the tunneling barrier is determined. Next results of ²H-spin–lattice relaxation measurements for a selectively η² − D₂ labeled isotopomer of the complex W(PCy₃)₂(CO)₃)(η² − D₂) are presented and discussed. The relaxation measurements are analyzed in terms of a simple one dimensional Bell tunnel model and comparison to incoherent neutron scattering (INS) data from the H₂ complex. The comparison reveals a strong isotope effect of 2 × 10³ for the exchange rates of the deuterons versus hydrons.     

Teachers' and Pupils' Behavior in Large and Small Classes: A Systematic Observation Study of Pupils Aged 10 and 11 Years.

The authors examined class size effects on teacher-pupil interactions, pupil engagement, and pupil-pupil interaction. They extended previous research by recognizing the hierarchical nature of observation data and the possible influence of other variables. The study used a time sampling method involving 257 children (aged 10-11 years) in 16 small (25 or under) and 26 large (31 and over) classes. In small classes, there were more individualized task-related contacts between teacher and pupils and a more active role for pupils. These results confirmed those from earlier research on children aged 4 and 5 years. Against expectation, class size did not affect pupil on-task behavior or peer interaction. There was a moderating role for school subject and a beneficial effect of teaching assistants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reciprocal Associations Between Adolescent Sexual Activity and Quality of Youth-Parent Interactions.

The authors examined differences in adolescents' relationships with their parents before and after adolescent first sexual activity. Participants were 13,570 members of the core sample of the National Longitudinal Survey of Adolescent Health (Add Health) Waves 1 and 2. Path analyses examined changes in parent-adolescent closeness, shared activities, and problem-focused interactions associated with changes in sexual activity separately for sons and daughters and for mothers and fathers. Race, religion, age, urbanicity, and parents' education were controls. Results confirm that increased problem-focused interactions and decreased parental closeness and shared activities both precede and follow adolescent sexual activity. Maintaining positive parental relations after adolescent first sexual activity is discussed as a means to reduce risks associated with sex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resonant charge transfer in back-scattering of H-atoms from the Cs adsorbates on the Cs/Cu(1 1 1) surface

We use the wave packet propagation approach to study the dynamics of resonant charge transfer in hydrogen back-scattering from Cs adsorbates on Cu(1 1 1). The affinity level of the projectile strongly interacts with an adsorbate-localized state leading to an important modification of the projectile–substrate resonant charge transfer. At very low collision energies (<2.5 eV) the adiabatic evolution of the system leads to the blocking of the negative ion formation in back-scattering of neutral hydrogen atoms from Cs adsorbate. At higher energies non-adiabatic transitions exist, and negative ion formation is possible.     

Surface spin polarization in Fe(1 1 0) and Ni(1 1 0)

The magnetism of Ni(1 1 0) and Fe(1 1 0) surfaces was investigated by electron capture spectroscopy. He⁺ and He²⁺ ions impinged on the Fe(1 1 0) and Ni(1 1 0) surfaces under grazing incidence, and the degree of polarization of the light emitted by the neutralized projectiles was analyzed. Our measurements show that in Ni(1 1 0) minority electrons have a higher density of states at the Fermi energy than majority electrons, opposed to the Fe(1 1 0) case. From a comparison of our measurements we estimate the ratio between captured minority and majority electrons in Ni(1 1 0) to be similar as the ratio between captured majority and minority electrons in Fe(1 1 0).     

超分子聚合物科学与工程

从超分子聚合物化学(合成与机理)，超分子聚合物物理(结构和性能)和超分子聚合物工程(加工与应用)三个方面综述超分子聚合物科学与工程的内容和进展．     

在线群体交互的影响模型及其学习算法

在线群体交互有助于数字图书馆发挥其服务人类需求的潜力，但如何量化在线群体交互对个人信息访问方面的影响还有待进一步研究．该文用隐Markov模型(HMM)来建模交互用户的状态序列及其相应的信息搜索行为，并基于影响模型理论提出了一个在线群体交互影响模型来分析用户在从数字图书馆选择资料和搜索所需信息时的相互影响．为满足本应用问题中增量模型学习的需要，文章还从耦合隐Markov模型(CHMM)学习算法引申出基于梯度的方法来进行在线群体交互影响模型参数的训练．实验结果显示，本文所提出的模型和算法能较准确地刻画在线群体交互对个人信息访问行动的影响．     

Effect of interactions between voltage and current harmonics on the net harmonic current produced by single phase non-linear loads

The effect of the interaction between both load voltage and current harmonics on the net harmonic current produced by different types of single phase non-linear loads is investigated. Two types of loads are considered: the fluorescent lamps' load and single phase diode bridge rectifiers' load. Studies are done on each load alone and then on the combination of both. The electromagnetic transient program has been used to model these loads. The computer simulations are supported by laboratory testing. The main conclusion of this work is that neglecting the interactions between both voltage and current harmonics will result in incorrect estimation of the harmonic current produced by these loads. Also it is concluded that using a combination of different types of loads can result in a reduction of the current and voltage distortions.     

MING-I: a distributed interactive multimedia document development mechanism

The next generation of interactive multimedia documents can contain both static media, e.g., text, graph, image, and continuous media, e.g., audio and video, and can provide user interactions in distributed environments. However, the temporal information of multimedia documents cannot be described using traditional document structures, e.g., Open Document Architecture (ODA) and Standard Generalized Mark-up Language (SGML); the continuous transmission of media units also raises some new synchronization problems, which have not been met before, for processing user interactions. Thus, developing a distributed interactive multimedia document system should resolve the issues of document model, presentation control architecture, and control scheme. In this paper, we (i) propose a new multimedia document model that contains the logical structure, the layout structure, and the temporal structure to formally describe multimedia documents, and (ii) point out main interaction-based synchronization problems, and propose a control architecture and a token-based control scheme to solve these interaction-based synchronization problems. Based on the proposed document model, control architecture, and control scheme, a distributed interactive multimedia document development mechanism, which is called MING-I, is developed on SUN workstations.