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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Syntaktická analýza založená na párových automatech / Syntactic Analysis Based on Coupled Finite Automata

Zámečníková, Eva Unknown Date (has links)
Master's thesis is dealing with translation based on coupled finite automaton model. Coupled finite automaton contains input and output automaton. The input automaton makes syntactic analysis with an input string. Used rules from the input automaton control the output automaton, which generates an output string. In thesis is described a way of determinisation of the input automaton without loss of information about rules used in original automaton. The determinizitaion is divided into two parts - for finite and infinite translation specified by transducers. Then is presented a new pair automaton with increased computing power. This increased computing power consists in replace of input or output or just a part of automaton by context free grammar.
2

Engine Speed Based Estimation of the Indicated Engine Torque / Varvtalsbaserad estimering av indikerat motormoment

Hellström, Magnus January 2005 (has links)
<p>The aim of this master's thesis is to implement and evaluate a method for estimating the indicated engine torque. The method is developed by IAV GmbH, Fraunhofer-Institut and Audi AG. The determination of the indicated torque is based on high resolution engine speed measurements. The engine speed is measured with a hall sensor, which receives the signal from the transmitterwheel mounted on the crankshaft. A transmitterwheel compensation is done to compensate for the partition defects that arises in the production and thus enable a more precise calculation of the angular velocity. The crankshaft angle, angular velocity and angular acceleration are estimated and the helpvariable effective torque is calculated using these signals as input. Through a relationship between effective torque and the indicated pressure the indicated pressure is extracted from a map. The indicated torque is then calculated from the pressure. </p><p>The method is validated with data from an engine test bed. Because of the low obtainable sample rate at the test bed, 4MHz, quantisation errors arises at engine speeds over 1000 rpm. Therefore the model is validated for low engine speeds and the result is promising.</p>
3

Engine Speed Based Estimation of the Indicated Engine Torque / Varvtalsbaserad estimering av indikerat motormoment

Hellström, Magnus January 2005 (has links)
The aim of this master's thesis is to implement and evaluate a method for estimating the indicated engine torque. The method is developed by IAV GmbH, Fraunhofer-Institut and Audi AG. The determination of the indicated torque is based on high resolution engine speed measurements. The engine speed is measured with a hall sensor, which receives the signal from the transmitterwheel mounted on the crankshaft. A transmitterwheel compensation is done to compensate for the partition defects that arises in the production and thus enable a more precise calculation of the angular velocity. The crankshaft angle, angular velocity and angular acceleration are estimated and the helpvariable effective torque is calculated using these signals as input. Through a relationship between effective torque and the indicated pressure the indicated pressure is extracted from a map. The indicated torque is then calculated from the pressure. The method is validated with data from an engine test bed. Because of the low obtainable sample rate at the test bed, 4MHz, quantisation errors arises at engine speeds over 1000 rpm. Therefore the model is validated for low engine speeds and the result is promising.
4

Syntactic Complexities of Nine Subclasses of Regular Languages

Li, Baiyu January 2012 (has links)
The syntactic complexity of a regular language is the cardinality of its syntactic semigroup. The syntactic complexity of a subclass of the class of regular languages is the maximal syntactic complexity of languages in that class, taken as a function of the state complexity n of these languages. We study the syntactic complexity of suffix-, bifix-, and factor-free regular languages, star-free languages including three subclasses, and R- and J-trivial regular languages. We found upper bounds on the syntactic complexities of these classes of languages. For R- and J-trivial regular languages, the upper bounds are n! and ⌊e(n-1)!⌋, respectively, and they are tight for n >= 1. Let C^n_k be the binomial coefficient ``n choose k''. For monotonic languages, the tight upper bound is C^{2n-1}_n. We also found tight upper bounds for partially monotonic and nearly monotonic languages. For the other classes of languages, we found tight upper bounds for languages with small state complexities, and we exhibited languages with maximal known syntactic complexities. We conjecture these lower bounds to be tight upper bounds for these languages. We also observed that, for some subclasses C of regular languages, the upper bound on state complexity of the reversal operation on languages in C can be met by languages in C with maximal syntactic complexity. For R- and J-trivial regular languages, we also determined tight upper bounds on the state complexity of the reversal operation.
5

Syntactic Complexities of Nine Subclasses of Regular Languages

Li, Baiyu January 2012 (has links)
The syntactic complexity of a regular language is the cardinality of its syntactic semigroup. The syntactic complexity of a subclass of the class of regular languages is the maximal syntactic complexity of languages in that class, taken as a function of the state complexity n of these languages. We study the syntactic complexity of suffix-, bifix-, and factor-free regular languages, star-free languages including three subclasses, and R- and J-trivial regular languages. We found upper bounds on the syntactic complexities of these classes of languages. For R- and J-trivial regular languages, the upper bounds are n! and ⌊e(n-1)!⌋, respectively, and they are tight for n >= 1. Let C^n_k be the binomial coefficient ``n choose k''. For monotonic languages, the tight upper bound is C^{2n-1}_n. We also found tight upper bounds for partially monotonic and nearly monotonic languages. For the other classes of languages, we found tight upper bounds for languages with small state complexities, and we exhibited languages with maximal known syntactic complexities. We conjecture these lower bounds to be tight upper bounds for these languages. We also observed that, for some subclasses C of regular languages, the upper bound on state complexity of the reversal operation on languages in C can be met by languages in C with maximal syntactic complexity. For R- and J-trivial regular languages, we also determined tight upper bounds on the state complexity of the reversal operation.
6

Ověřování parametrických vlastností nad záznamy běhů programů / Parametric Properties for Log Checker

Mutňanský, Filip January 2020 (has links)
The goal of this thesis is to implement a tool that based on user defined properties can verify sequences of events in the traces of the program, or the log file. Properties are defined in extended regular expressions. The tool is able to verify parametric properties. User can define relations between parameters of events. Input of this tool is the definition of properties and constraints of parameters. Output of the tool is the report of violated properties with its sequences of events that caused the error.
7

Protecting Network Processors with High Performance Logic Based Monitors

Kumarapillai Chandrikakutty, Harikrishnan 01 January 2013 (has links) (PDF)
Technological advancements have transformed the way people interact with the world. The Internet now forms a critical infrastructure that links different aspects of our life like personal communication, business transactions, social networking, and advertising. In order to cater to this ever increasing communication overhead there has been a fundamental shift in the network infrastructure. Modern network routers often employ software programmable network processors instead of ASIC-based technology for higher throughput performance and adaptability to changing resource requirements. This programmability makes networking infrastructure vulnerable to new class of network attacks by compromising the software on network processors. This issue has resulted in the need for security systems which can monitor the behavior of network processors at run time. This thesis describes an FPGA-based security monitoring system for multi-core network processors. The implemented security monitor improves upon previous hardware monitoring schemes. We demonstrate a state machine based hardware programmable monitor which can track program execution flow at run time. Applications are analyzed offline and a hash of the instructions is generated to form a state machine sequence. If the state machine deviates from expected behavior, an error flag is raised, forcing a network processor reset. For testing purposes, the monitoring logic along with the multi-core network processor system is implemented in FPGA logic. In this research, we modify the network processor memory architecture to improve security monitor functionality. The efficiency of this approach is validated using a diverse set of network benchmarks. Experiments are performed on the prototype system using known network attacks to test the performance of the monitoring subsystem. Experimental results demonstrate that out security monitor approach provides an efficient monitoring system in detecting and recovering from network attacks with minimum overhead while maintaining line rate packet forwarding. Additionally, our monitor is capable of defending against attacks on processor with a Harvard architecture, the dominant contemporary network processor organization. We demonstrate that our monitor architecture provides no network slowdown in the absence of an attack and provides the capability to drop packets without otherwise affecting regular network traffic when an attack occurs.
8

Měření spolehlivosti vyhledávání vzorů / Reliability Measurement of the Pattern Matching

Dvořák, Milan January 2012 (has links)
This thesis deals with the pattern matching methods based on finite automata and describes their optimizations. It presents a methodology for the measurement of reliability of pattern matching methods, by comparing their results to the results of the PCRE library. Experiments were conducted for a finite automaton with perfect hashing and faulty transition table. Finally, the resulting reliability evaluation of the algorithm is shown and possible solutions of the identified problems are proposed.
9

OPTIMALIZACE ALGORITMŮ A DATOVÝCH STRUKTUR PRO VYHLEDÁVÁNÍ REGULÁRNÍCH VÝRAZŮ S VYUŽITÍM TECHNOLOGIE FPGA / OPTIMIZATION OF ALGORITHMS AND DATA STRUCTURES FOR REGULAR EXPRESSION MATCHING USING FPGA TECHNOLOGY

Kaštil, Jan Unknown Date (has links)
Disertační práce se zabývá rychlým vyhledáváním regulárních výrazů v síťovém provozu s použitím technologie FPGA. Vyhledávání regulárních výrazů v síťovém provozu je výpočetně náročnou operací využívanou převážně v oblasti síťové bezpečnosti a v oblasti monitorování provozu vysokorychlostních počítačových sítí. Současná řešení neumožňují dosáhnout požadovaných multigigabitových propustností při dodržení všech požadavků, které jsou na vyhledávací jednotky kladeny. Nejvyšších propustností dosahují implementace založené na využití inovativních hardwarových architektur implementovaných v FPGA případně v ASIC. Tato disertační práce popisuje nové architektury vyhledávací jednotky, které jsou vhodné pro implementaci jak v FPGA tak v ASIC. Základní myšlenkou navržených architektur je využití perfektní hashovací funkce pro implementaci přechodové tabulky konečného automatu. Dále byla navržena architektura, která umožňuje uživateli zanést malou pravděpodobnost chyby při vyhledávání a tím snížit paměťové nároky vyhledávací jednotky. Disertační práce analyzuje vliv pravděpodobnosti této chyby na celkovou spolehlivost systému a srovnává ji s řešením používaným v současnosti. V rámci disertační práce byla provedena měření vlastností regulárních výrazů používaných při analýze provozu moderních počítačových sítí. Z provedené analýzy vyplývá, že velká část regulárních výrazů je vhodná pro implementaci pomocí navržených architektur. Pro dosažení vysoké propustnosti vyhledávací jednotky práce navrhuje nový algoritmus transformace abecedy, který umožňuje, aby vyhledávací jednotka zpracovala více znaků v jednom kroku. Na rozdíl od současných metod, navržený algoritmus umožňuje konstrukci automatu zpracovávajícího libovolný počet symbolů v jednom taktu. Implementované architektury dosahují v porovnání se současnými metodami úspory paměti zlepšení až 200MB.
10

Hledání regulárních výrazů s využitím technologie FPGA / Fast Regular Expression Matching Using FPGA

Kaštil, Jan January 2008 (has links)
The thesis explains several algorithms for pattern matching. Algorithms work in both software and hardware. A part of the thesis is dedicated to extensions of finite automatons. The second part explains hashing and introduces concept of perfect hashing and CRC. The thesis also includes a suggestion of possible structure of a pattern matching unit based on deterministic finite automatons in FPGA. Experiments for determining the structure and size of resulting automatons were done in this thesis.

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