1,701 research outputs found
A Boyer-Moore (or Watson-Watson) type algorithm for regular tree pattern matching
No full textIn this chapter, I outline a new algorithm for regular tree pattern matching. The existence of this algorithm was first mentioned in the statements accompanying my dissertation, [2]. In order to avoid repeating the material in my dissertation, it is assumed that the reader is familiar with Chapters 4 and 5 of the dissertation.
[2] WATSON, B.W. Taxonomies and Toolkits of Regular Language Algorithms, Ph.D dis
sertation, Faculty of Computing Science, Eindhoven University of Technology, The
Netherlands, 1995, ISBN 90-386-0396-7
Hardcoding and dynamic implementation of finite automata
Get PDFThe theoretical complexity of a string recognizer is linear to the length of the string being tested for acceptance. However, for some kind of strings the processing time largely depends on the number of states visited by the recognizer at run-time. Various experiments are conducted in order to compare the time efficiency of both hardcoded and table-driven algorithms when using such strings patterns. The results of the experiments are cross-compared in order to show the efficiency of the hardcoded algorithm over its table-driven counterpart. This help further the investigations on the problem of the dynamic implementation of finite automata. It is shown that we can rely on the history of the states previously visited in the dynamic framework in order to predict the suitable algorithm for acceptance testing
Stretching and jamming of finite automata
Get PDFIn this paper we present two transformations on automata, called stretching and jamming. These transformations will, under certain conditions, reduce the size of the transition table, and under other conditions reduce the string processing time. Given a finite automaton, we can stretch it by transforming each single transition into two or more sequential transitions, thereby introducing additional intermediate states. Jamming is the inverse transformation, in which two or more successive transitions are transformed into a single transition, thereby removing redundant intermediate states. We will present formal definitions of stretching and jamming and we will calculate theoretical bounds, when stretching/jamming is effective in terms of memory consumption
Damage to human hearing by airborne sound of very high frequency or ultrasonic frequency
No full textThis literature review examines the audiological, occupational hygiene and industrial safety literature on the subjective and auditory effects of audible sound in the very high frequency range (10-20 kHz) and also in the inaudible ultrasonic range (greater than 20 kHz, generally thought to be the upper frequency limit of young normal hearing). Exposure limits have been proposed, with the intent of avoiding any subjective effects and any auditory effects, in any exposed individuals. The evolution of these internationally recognised Damage Risk Criteria and Maximum Permitted Levels has been examined critically. Conclusions and recommendations are offered in respect of hearing damage and adverse subjective effects caused by sounds outside the customary frequency range for occupational noise exposure assessments. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author and do not necessarily reflect HSE policy
Projeto e implementação de um nucleo de sistema operacional distribuido com mecanismos para tempo real
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina. Centro TecnologicoA presente dissertação apresenta o projeto e a implementação de um núcleo de Sistema Operacional Distribuído. O referido núcleo é responsável pela implantação de um ambiente multitarefas distribuído. As necessidades de tempo real são tratadas através de política de escalonamento e mecanismo de temporização. O núcleo fornece um conjunto de primitivas de comunicação e sincronização entre tarefas (IPC) que permitem uma comunicação uniforme e independente da distribuição no sistema, com diferentes possibilidades de sincronismos (síncronas e assíncronas) e modos de endereçamento (um-para-um, um-para-vários, etc.). O núcleo fornece ainda o suporte para a configuração estática e dinâmica (reconfiguração) de um sistema distribuído. Este núcleo foi desenvolvido como parte do Ambiente de Desenvolvimento e Execução de Software (ADES) que corresponde a um conjunto de ferramentas cujo objetivo é facilitar a concepção de software distribuído. Este ambiente está centrado sobre uma Linguagem de Implementação de Sistema (LIS), sendo que o núcleo em questão fornece então suporte de tempo de execução para abstrações definidas por esta linguagem
Gender differences in self-reported late effects, quality of life and satisfaction with clinic in survivors of lymphoma
No full textObjectives: gender differences in perceived vulnerability to late effects and views about follow-up among cancer survivors have received little attention. As lymphoma affects both genders similarly, we compared the consequences of cancer (late effects, perceived vulnerability and quality of life (health-related quality of life (HRQoL)), and satisfaction with clinic visits between genders.Methods: a cohort of 115 younger adults (18–45 years, >5 years disease-free survival), who had been treated for lymphoma participated. Questionnaires (n = 91) were completed before and after (n = 62) routine consultant-led appointments. Survivors (n = 24) without appointments were recruited by post. Questionnaires included HRQoL, late effects, perceived vulnerability, issues survivors wanted to discuss and reported discussing in clinic, time waiting in clinic and consultation satisfaction.Results: there were no gender differences in number of self-reported late effects or perceived vulnerability. Men with more late effects reported worse psychological HRQoL (r = 0.50, p<0.001). While men wanted to discuss more topics than they did, women were able to discuss the topics they wanted (ANOVA, p = 0.01). Multiple regression analyses showed a shorter wait in clinic (r = ?0.46, p = 0.009) and discussing more topics (r = 0.34, p = 0.06) explained 30.6% of the variance in consultation satisfaction for men.Conclusions: issues surrounding follow-up provision are increasingly important given the length of survival in young adults following treatment for lymphoma. Men may experience poor psychological well-being due to distress about unanswered concerns. Consideration of their concerns should be prioritised, given that satisfaction and ultimately continued attendance at clinic and HRQoL may be dependent on the extent to which follow-up meets survivors' expectation
The Performance of Single-Keyword and Multiple-Keyword Pattern Matching Algorithms
Get PDFThis paper presents a toolkit of pattern matching algorithms, performance data on the algorithms, and recommendations for the selection of an algorithm (given a particular application) . The pattern matching problem is: given a finite non-empty set of keywords and an input string, find all occurrences of any of the keywords in the input string. The pattern matching toolkit (written in the C programming language, and freely available) contains implementations of the Knuth-Morris-Pratt, Boyer-Moore, Aho-Corasick, and Commentz-Walter algorithms. The algorithms are implemented directly from the abstract algorithms derived and presented in the taxonomy of Watson and Zwaan [WZ92]. The toolkit provides one of the few known correct implementations of the Commentz-Walter precomputation algorithm. The performance of all of the algorithms (running on a variety of workstation hardware) was measured on two types of input: English text and genetic sequences. The input data, which is the same as that..
Instantaneous planar pressure determination from PIV in turbulent flow
Get PDFThis paper deals with the determination of instantaneous planar pressure fields from velocity data obtained by particle image velocimetry (PIV) in turbulent flow. The operating principles of pressure determination using a Eulerian or a Lagrangian approach are described together with theoretical considerations on its expected performance. These considerations are verified by a performance assessment on a synthetic flow field. Based on these results, guidelines regarding the temporal and spatial resolution required are proposed. The interrogation window size needs to be 5 times smaller than the flow structures and the acquisition frequency needs to be 10 times higher than the corresponding flow frequency (e.g. Eulerian time scales for the Eulerian approach). To further assess the experimental viability of the pressure evaluation methods, stereoscopic PIV and tomographic PIV experiments on a square cylinder flow (ReD = 9,500) were performed, employing surface pressure data for validation. The experimental results were found to support the proposed guidelines.Aerospace Engineerin
Implementation and application of automata : 6th international conference, CIAA 2001, Pretoria, South Africa, July 23-25, 2001 : revised papers
No full textImplementation and application of automata : 6th international conference, CIAA 2001, Pretoria, South Africa, July 23-25, 2001 : revised papers
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