强化学习算法中启发式回报函数的设计及其收敛性分析

回报函数设计的好与坏对学习系统性能有着重要作用,按回报值在状态-动作空间中的分布情况,将回报函数的构建分为两种形式:密集函数和稀疏函数,分析了密集函数和稀疏函数的特点.提出启发式回报函数的基本设计思路,利用基于保守势函数差分形式的附加回报函数,给学习系统提供更多的启发式信息,并对算法的最优策略不变性和迭代收敛性进行了证明.启发式回报函数能够引导学习,加快学习进程,从而可以实现强化学习在实际大型复杂系统应用中的实时控制和调度.

动物地磁导航磁受体的磁学探测及其矿化机理研究

This thesis focuses on the study of the geomagnetic orientation and navigation of homing pigeon and migrating bats. Magnetic minerals, possibly the base of the “magnetoreceptors”, which can perceive the magnetic information from geomagnetic field, are studied using advanced mineral magnetic methods in combination of non-magnetic techniques. In addition, the mechanism of magnetite biomineralization in organism has been probed through the formation of ferritin under laboratory-controlled conditions. A series of magnetic measurements of selected pigeon samples found the biogenic magnetite particles. a significant rapid decay of SIRM5K in the interval of 5–20 K on both zero-field cooled and field cooled warming curves suggests the dominance of superparamagnetic particles in the samples. Additionally, we noted that the content of magnetite particles in the male and the female are different. It is also found that bats contain magnetite. The results of room temperature magnetic measurements of Rhinolophus ferrumequinum and Chaerophon　plicatus samples indicates there are magnetite in the heads of bats. The concentration of magnetic materials in the brain is higher than that in the skull. The results of low temperature magnetic measurements in Nyctalus plancyi samples show that the head may contain a small quantity of magnetite particles. In order to study the magnetite biomineralizaiton, ferritin was reconstituted. The results of electron nanodiffraction patterns indicate that the dominant mineral phases in the reconstituted ferritin are ferrihydrite, which is similar to that in the native ferritin. The blocking temperature (TB) is near 20K. A series of magnetic hysteresis at low temperatures (3-21K) show the wasp-waisted hysteresis loop. This can be interpreted by either grain size effects (SP + SD) or different coercivities minerals.

Cross-Border Unitization and Joint Development Agreements: An International Law Perspective

Okoye, Adaeze, et al, 'Cross-Border Unitization and Joint Development Agreements: An International Law Perspective', Houston Journal of International Law (2007) 29(2) pp.355-425 RAE2008

Can Institutions Have Responsibilities? Collective Moral Agency and International Relations

Erskine, Toni, Can Institutions Have Responsibilities? Collective Moral Agency and International Relations (New York: Palgrave Macmillan, 2004), pp.xii+241 RAE2008

Optymalizacja metod analizy Főrsterowskiego rezonansowego przeniesienia energii (FRET) pojedynczych cząsteczek

Wydział Chemii: Zakład Chemii Fizycznej

Spuścizny konserwatorów zbiorów, kierowników i dyrektorów Biblioteki Poznańskiego Towarzystwa Przyjaciół Nauk

Artykuł prezentuje sylwetki konserwatorów zbiorów, kierowników i dyrektorów Biblioteki Poznańskiego Towarzystwa Przyjaciół Nauk (PTPN) oraz to, co po nich pozostało w postaci archiwaliów. Od momentu powstania Biblioteka PTPN gromadziła rękopisy lub całe spuścizny wybitnych osób, w tym kierujących tą placówką. Również inne biblioteki i archiwa zakładowe instytucji, z którymi byli oni związani, włączały do swych zbiorów ich materiały archiwalne. Spuścizny Ludwiki Dobrzyńskiej-Rybickiej i Ryszarda Marciniaka znajdują się zarówno w Bibliotece PTPN, jak i w Polskiej Akademii Nauk Archiwum w Warszawie Oddział w Poznaniu. Znaczna część materiałów archiwalnych Bolesława Erzepkiego trafiła natomiast do Działu Zbiorów Specjalnych Biblioteki Raczyńskich w Poznaniu. Szczątkowe materiały archiwalne można też znaleźć w Archiwum Uniwersytetu im. Adama Mickiewicza w Poznaniu (Ludwika Dobrzyńska-Rybicka) oraz w Archiwum Biblioteki Uniwersyteckiej w Poznaniu (Ludwika Dobrzyńska-Rybicka, Jan Baumgart, Aniela Koehlerówna).

Mieszanie stanów magnetycznych w skończonych układach spinowych opisywanych modelem Heisenberga

Wydział Fizyki: Zakład Fizyki Komputerowej

Kształtowanie systemu politycznego Kazachstanu w latach 1991-2000. Kontekst historyczno-kulturowy

Wydział Historyczny

Refugee Question as an International Global Problem

The problem of refugees is a phenomenon characteristic of contemporary international relations. It can take an individual form (as a result of individual persecutions of a racial, religious, national or political character) or the form of mass relocations, especially in the face of military conflicts or general breaching of human rights. The purpose of this paper is to present the refugee question as an international global problem that may appear in any region of the world, impacting the situation of states and societies, that is perceived as both a threat and a fundamental challenge for the entire international community.

Współpraca i rywalizacja państw jako czynnik kształtujący bezpieczeństwo międzynarodowe w Azji Północno-Wschodniej na początku XXI wieku

Wydział Nauk Politycznych i Dziennikarstwa

Revoluções no fotojornalismo

Tese apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em Ciências da Informação, especialidade em Jornalismo

Orientational Harmonic Model for Rotation, Translation, and Scale Invariant Pattern Representation in Biological Vision

The proposed model, called the combinatorial and competitive spatio-temporal memory or CCSTM, provides an elegant solution to the general problem of having to store and recall spatio-temporal patterns in which states or sequences of states can recur in various contexts. For example, fig. 1 shows two state sequences that have a common subsequence, C and D. The CCSTM assumes that any state has a distributed representation as a collection of features. Each feature has an associated competitive module (CM) containing K cells. On any given occurrence of a particular feature, A, exactly one of the cells in CMA will be chosen to represent it. It is the particular set of cells active on the previous time step that determines which cells are chosen to represent instances of their associated features on the current time step. If we assume that typically S features are active in any state then any state has K^S different neural representations. This huge space of possible neural representations of any state is what underlies the model's ability to store and recall numerous context-sensitive state sequences. The purpose of this paper is simply to describe this mechanism.

Dilute nitride semiconductors : band structure, scattering and high field transport

The substitution of a small fraction x of nitrogen atoms, for the group V elements in conventional III-V semiconductors such as GaAs and GaSb strongly perturbs the conduction band of the host semiconductor. In this thesis we investigate the effects of nitrogen states on the band dispersion, carrier scattering and mobility of dilute nitride alloys. In the supercell model we solve the single particle Hamiltonian for a very large supercell containing randomly placed nitrogen. This model predicts a gap in the density of states of GaNxAs1−x, where this gap is filled in the Green’s function model. Therefore we develop a self-consistent Green’s function (SCGF) approach, which provides excellent agreement with supercell calculations and reveals a gap in the DOS, in contrast with the results of previous non-self-consistent Green’s function calculations. However, including the distribution of N states destroys this gap, as seen in experiment. We then examine the high field transport of carriers by solving the steadystate Boltzmann transport equation and find that it is necessary to include the full distribution of N levels in order to account for the small, low-field mobility and the absence of a negative differential velocity regime observed experimentally with increasing x. Overall the results account well for a wide range of experimental data. We also investigate the band structure, scattering and mobility of carriers by finding the poles of the SCGF, which gives lower carrier mobility for GaNxAs1−x, compared to those already calculated, in better agreement with experiments. The calculated optical absorption spectra for InyGa1−yNxAs1−x and GaNxSb1−x using the SCGF agree well with the experimental data, confirming the validity of this approach to study the band structure of these materials.

A framework for state-based time-series analysis and prediction

Time-series analysis and prediction play an important role in state-based systems that involve dealing with varying situations in terms of states of the world evolving with time. Generally speaking, the world in the discourse persists in a given state until something occurs to it into another state. This paper introduces a framework for prediction and analysis based on time-series of states. It takes a time theory that addresses both points and intervals as primitive time elements as the temporal basis. A state of the world under consideration is defined as a set of time-varying propositions with Boolean truth-values that are dependent on time, including properties, facts, actions, events and processes, etc. A time-series of states is then formalized as a list of states that are temporally ordered one after another. The framework supports explicit expression of both absolute and relative temporal knowledge. A formal schema for expressing general time-series of states to be incomplete in various ways, while the concept of complete time-series of states is also formally defined. As applications of the formalism in time-series analysis and prediction, we present two illustrating examples.

Analytically continued generalized continuum distorted waves

The continuum distorted-wave eikonal-initial-state (CDW-EIS) theory of Crothers and McCann (Crothers DSF and McCann JF, 1983 J. Phys. B: At. Mol. Opt. Phys. 16 3229 ) used to describe ionization in ion-atom collisions is generalized (G) to GCDW-EIS, to incorporate the azimuthal ange dependence into the final-state wavefunction. This is accomplished by the analytic continuation of hydrogenic-like wavefunctions from below to above threshold, using parabolic coordinates and quantum numbers including magnetic quantum numbers, thus providing a more complete set of states. At impact energies lower than 25 ke V u^{-1}, the total CDW-EIS ionization cross section falls off, with decreasing energy, too quickly in comparison with experimental data by Crothers and McCann. The idea behind and motivation for the GCDW-EIS model is to improve the theory with respect to experiment, by including contributions from non-zero magnetic quantum numbers. We also therefore incidentally provide a new derivation of the theory of continuum distorted waves for zero magnetic quantum numbers while simultaneously generalizing it.