Efficient Identification of Redundant Actions in Plans

Při hledání plánů je často velmi složité najít ten optimální. Najít jakýkoli plán bývá mnohem snazší. Takto vzniklé plány mohou být často snadno vylepšeny a zkráceny. Jedním ze způsobů optimalizace plánu je identifikování zbytečných akcí a jejich následné odstranění. V této práci se zaměříme na implementaci několika metod, kterými toho lze dosáhnout. Představíme dvě optimalizace, jimiž lze zkoumané metody zrychlit. Navrhneme novou metodu, jenž bude inspirovaná původními metodami a námi vyvinutými optimalizacemi. Na závěr všechny metody porovnáme na problémech používaných na International Planning Competition a vzneseme podněty pro další výzkum.Finding an optimal plan can be very difficult. However, finding any plan is often much easier. Since these plans are suboptimal, they may be optimized and shortened. One way to achieve this is to identify and remove redundant actions. This work focuses on methods, which were designed to perform such optimization. We will introduce two approaches, which will speed up the examined methods. Then we will propose a new method inspired by the aforementioned ones and their new optimizations. In the end, we will compare all the methods on several benchmarks from the International Planning Competitions and propose topics for further research

Parametric design in a Garden and Landscape architecture

Diploma thesis explores use of parametric design method in the field of landscape and garden architecture. Parametric design is used as a tool. The aim is to find a method to use it in each phase of the design process, to reach effectivity and a new aesthetical approach. Research of projects already published is the basis for further use. Design process is presented in the project part of the diploma thesis. Use of each parameter input is explained. Experimental forms and efficacy of design is the output result

On Speeding Up Methods for Identifying Redundant Actions in Plans

Satisficing planning aims at generating plans that are not necessarily optimal. Often, minimising plan generation time negatively affects quality of generated plans. Acquiring plans quickly might be of critical importance in decision-making systems that operate nearly in realtime. However, (very) suboptimal plans might be expensive to execute and more prone to failures. Optimising plans after they are generated, in a spare time, can improve their quality. This paper focuses on speeding up the (Greedy) Action Elimination methods, which are used for identifying and removing redundant actions from plans in polynomial time. We present two enhancements of these methods: Plan Action Landmarks, actions that are not redundant in a given plan, and Action Cycles which are subsequences of actions which if removed do not affect the state trajectory after the last action of the cycle. We evaluate the introduced methods on benchmark problems from the Agile tracks of the International Planning Competition and on plans generated by several state-of-the-art planners, successful in the recent editions of the competition

Real-time observation of water radiolysis and hydrated electron formation induced by extreme-ultraviolet pulses

The dominant pathway of radiation damage begins with the ionization of water. Thus far, however, the underlying primary processes could not be conclusively elucidated. Here, we directly study the earliest steps of extreme ultraviolet (XUV)–induced water radiolysis through one-photon excitation of large water clusters using time-resolved photoelectron imaging. Results are presented for H2O and D2O clusters using femtosecond pump pulses centered at 133 or 80 nm. In both excitation schemes, hydrogen or proton transfer is observed to yield a prehydrated electron within 30 to 60 fs, followed by its solvation in 0.3 to 1.0 ps and its decay through geminate recombination on a ∼10-ps time scale. These results are interpreted by comparison with detailed multiconfigurational non-adiabatic ab-initio molecular dynamics calculations. Our results provide the first comprehensive picture of the primary steps of radiation chemistry and radiation damage and demonstrate new approaches for their study with unprecedented time resolution.ISSN:2375-254

Vibrationally Mediated Stabilization of Electrons in Nonpolar Matter

International audienceWe explore solvation of electrons in nonpolar matter, here represented by butadiene clusters. Isolated butadiene supports only the existence of transient anions (resonances). Two-dimensional electron energy loss spectroscopy shows that the resonances lead to an efficient vibrational excitation of butadiene, which can result into the almost complete loss of energy of the interacting electron. Cluster-beam experiments show that molecular clusters of butadiene form stable anions, however only at sizes of more than 9 molecular units. We have calculated the distribution of electron affinities of clusters using classical and path integral molecular dynamics simulations. There is almost a continuous transition from the resonant to the bound anions with an increase in cluster size. The comparison of the classical and quantum dynamics reveals that the electron binding is strongly supported by molecular vibrations, brought about by nuclear zero-point motion and thermal agitation. We also inspected the structure of the solvated electron, finding it well localized

Reactivity of Hydrated Electron in Finite Size System: Sodium Pickup on Mixed N₂O–Water Nanoparticles

We investigate the reactivity of hydrated electron generated by alkali metal deposition on small water particles with nitrous oxide dopant by means of mass spectrometry and ab initio molecular dynamics simulations. The mixed nitrous oxide/water clusters were generated in a molecular beam and doped with Na atoms in a pickup experiment, and investigated by mass spectrometry using two different ionization schemes: an electron ionization (EI), and UV photoionization after the Na doping (NaPI). The NaPI is a soft-ionization nondestructive method, especially for water clusters provided that a hydrated electron <i>e</i>_s^– is formed in the cluster. The missing signal for the doped clusters indicates that the hydrated electron is not present in the N₂O containing clusters. The simulations reveal that the hydrated electron is formed, but it immediately reacts with N₂O, forming first N₂O^– radical anion, later O^–, and finally an OH^• and OH^– pair