Qualitative Analysis of POMDPs with Temporal Logic Specifications for Robotics Applications

We consider partially observable Markov decision processes (POMDPs), that are a standard framework for robotics applications to model uncertainties present in the real world, with temporal logic specifications. All temporal logic specifications in linear-time temporal logic (LTL) can be expressed as parity objectives. We study the qualitative analysis problem for POMDPs with parity objectives that asks whether there is a controller (policy) to ensure that the objective holds with probability 1 (almost-surely). While the qualitative analysis of POMDPs with parity objectives is undecidable, recent results show that when restricted to finite-memory policies the problem is EXPTIME-complete. While the problem is intractable in theory, we present a practical approach to solve the qualitative analysis problem. We designed several heuristics to deal with the exponential complexity, and have used our implementation on a number of well-known POMDP examples for robotics applications. Our results provide the first practical approach to solve the qualitative analysis of robot motion planning with LTL properties in the presence of uncertainty

Interface Simulation Distances

The classical (boolean) notion of refinement for behavioral interfaces of system components is the alternating refinement preorder. In this paper, we define a distance for interfaces, called interface simulation distance. It makes the alternating refinement preorder quantitative by, intuitively, tolerating errors (while counting them) in the alternating simulation game. We show that the interface simulation distance satisfies the triangle inequality, that the distance between two interfaces does not increase under parallel composition with a third interface, and that the distance between two interfaces can be bounded from above and below by distances between abstractions of the two interfaces. We illustrate the framework, and the properties of the distances under composition of interfaces, with two case studies.Comment: In Proceedings GandALF 2012, arXiv:1210.202

Stochastic Shortest Path with Energy Constraints in POMDPs

We consider partially observable Markov decision processes (POMDPs) with a set of target states and positive integer costs associated with every transition. The traditional optimization objective (stochastic shortest path) asks to minimize the expected total cost until the target set is reached. We extend the traditional framework of POMDPs to model energy consumption, which represents a hard constraint. The energy levels may increase and decrease with transitions, and the hard constraint requires that the energy level must remain positive in all steps till the target is reached. First, we present a novel algorithm for solving POMDPs with energy levels, developing on existing POMDP solvers and using RTDP as its main method. Our second contribution is related to policy representation. For larger POMDP instances the policies computed by existing solvers are too large to be understandable. We present an automated procedure based on machine learning techniques that automatically extracts important decisions of the policy allowing us to compute succinct human readable policies. Finally, we show experimentally that our algorithm performs well and computes succinct policies on a number of POMDP instances from the literature that were naturally enhanced with energy levels.Comment: Technical report accompanying a paper published in proceedings of AAMAS 201

EU Emissions Trading Scheme as Implemented in the Czech Republic

The paper reports on the implementation of the European Emissions Trading Scheme (EU ETS) in the Czech Republic. Trading in CO2 emission allowances is one of the most dynamic and progressive economic instruments of environmental policy. Since coming into force in January 2005, the system has incorporated into company decision making a truly new phenomenon – the price of carbon in the form of allowances tradable on the European market, where the price of the allowance represents the costs of a company when emitting one ton of CO2. The incentive, given by the opportunity costs should motivate operators of installations emitting CO2 to analyze options for carbon emission reduction and to behave rationally. In total, the system should result in a quite significant reduction in the compliance costs of CO2 reduction when compared to alternatives such as taxes or emission limits, as a result of flexibility given by the market.The most controversial and sensitive part of the system is the initial distribution of the allowances to emitters. The so-called National Allocation Plan has to provide answers to very difficult questions – to whom, how and how many allowances will be given. This paper focuses on a detailed description of the sectors and companies in the Czech Republic that are affected by the system and discusses various aspects of the scheme

Influence of electric discharges on bearings of electric machina

Bearing currents are one of cause’s bearings faults. The character of a lubricator belongs to main factor influencing an inception of bearing currents. We have analyzed the electric character variety kind of lubricators; the influence of lubricators on a bearing current was analyzed too. Some results from the mentioned research are introduced within this paper

Class-AB stereo audio power amplifier

Tato bakalářská práce se zabývá návrhem nízkofrekvenčního výkonového zesilovače v pracovní třídě AB včetně korekčního předzesilovače a vhodného napájecího zdroje. Zesilovač je navržen tak, aby byl realizovatelný z běžně dostupných součástek. Výsledkem práce je celkový návrh koncového zesilovače s předzesilovačem a napájecím zdrojem a změření jejich parametrů.This bachelor thesis deals with design of low-frequency power amplifier working in AB class, including correction preamplifier and a suitable power source. The amplifier is designed to be feasible from commonly available components. The result is the overall design of power amplifier with preamplifier and power supply and measuring their parameters.

Approaches to the study of spatial interactions in geography: an example of evaluation of transport relationships among settlement centres in Czechia

Spatial interactions considerably influence complex geographic organisation and the shaping of settlement structures, explaining and describing the importance of interrelationships in the landscape sphere on all scale levels. This is why they are called one of the crucial general terms of geography. When it comes to this topic, the biggest emphasis on it is primarily laid in the study of transport as well as transport networks that we can consider the main support for interactions. The topic of evaluation of spatial interactions or, if defined narrowly, of transport relationships, is characteristic due to its important interdisciplinary nature because the questions of interrelatedness of individual centres and their needs in the context of transport offer are dealt with by transport engineering fields, economic fields, land-use planning specialists, etc. Similarly to other spheres of social and economic geography, where this occurred earlier, present-day geography of transport is undergoing a change in the form of a variety of methodological approaches, "internal" specification of a more detailed delineation of the subject of study and new application challenges. As a rule, the topic of intensity and nature of transport relationships is associated with quantitative methods of cognition of the...Prostorové interakce významně ovlivňují komplexní geografickou organizaci, utváření sídelních struktur a vysvětlují a popisují význam vzájemných vztahů v krajinné sféře na všech měřítkových úrovních. Proto jsou označovány jako jeden z klíčových obecných pojmů geografie. Největší důraz je tomuto tématu věnován především ve studiu dopravy a dopravních sítí, které můžeme považovat za hlavní oporu interakcí. Problematika hodnocení prostorových interakcí, popř. v užším pojetí dopravních vztahů, je charakteristická významnou interdisciplinaritou, neboť otázky propojenosti jednotlivých středisek a jejich potřeb v kontextu úrovně dopravní nabídky řeší dopravně-inženýrské obory, ekonomické obory, specialisté v oblasti územního plánování atd. Obdobně jako o něco dříve jiné oblasti sociální a ekonomické geografie současná geografie dopravy prochází změnou v podobě plurality metodických přístupů, "vnitřní" specifikace detailnějšího vymezení objektu studia a nových aplikačních výzev. Problematika intenzity a povahy dopravních vztahů je zpravidla spojována s kvantitativními metodami poznání reality. Přesto je stále součástí významného počtu dopravně-geografických studií a zároveň je nadále aktuální, především s ohledem na aplikace v řešení praktických úloh dopravního plánování a rozhodovacích praktik v decizní...Department of Social Geography and Regional Develop.Katedra sociální geografie a region. rozvojeFaculty of SciencePřírodovědecká fakult