A suite of new collision avoidance systems (CAS) is presented for use in heavy vehicles whose structure and size necessarily impede driver visibility is introduced. The main goal of the project is to determine the appropriate use of each of the commercially available technologies and, where possible, produce a low cost variant suitable for use in proximity detection on large mining industry haul trucks. CAS variants produced were subjected to a field demonstration and, linked to the output from the earlier CAS 1 project, (a production high-definition in-cabin video monitor and r/f tagging system). The CAS 2 system used low cost Doppler continuous wave radar antennae coupled to the CAS 1 monitor to indicate the presence of an object moving at any speed above 3 Km/h relative to the antennae. The novelty of the CAS 3 system lies in the design of 3 interconnected, modules. The modules are 8 radar antennae (as used in CAS 2) modules located on the truck, software to interface with the end user (i.e. the drivers of the trucks) and a display unit. Modularisation enables the components to be independently tested, evaluated and replaced when in use. The radar antennae modules and the system as a whole are described together with the empirical tests conducted and results obtained. The tests, drawing on Monte-Carlo simulation techniques, demonstrate both the 'correctness' of the implementations and the effectiveness of the system. The results of the testing of the final prototype unit were highly successful both as a computer simulation level and in practical tests on light vehicles. A number of points, (as a consequence of the field test), are reviewed and their application to future projects discussed.

Fault management is a challenging task in all-optical wavelength division multiplexing (WDM) networks. However, fast fault localization for shared risk link groups (SRLGs) with multiple links is essential for building a fully survival and functional transparent all-optical mesh network. Monitoring trail (m-trail) technology is an effective approach to achieve the goal, whereby a set of m-trails are derived for unambiguous fault localization (UFL). However, an m-trail traverses through a link by utilizing a dedicated wavelength channel (WL), causing a significant amount of resource consumption. In addition, existing m-trail methods incur long and variable alarm dissemination delay. We introduce a novel framework of real-time fault localization in all-optical WDM mesh networks, called the monitoring-burst (m-burst), which aims at initiating a balanced trade-off between consumed monitoring resources and fault localization latency. The m-burst framework has a single monitoring node (MN) and requires one WL in each unidirectional link if the link is traversed by any m-trail. The MN launches short duration optical bursts periodically along each m-trail to probe the links of the m-trail. Bursts along different m-trails are kept non-overlapping through each unidirectional link by scheduling burst launching times from the MN and multiplexing multiple bursts, if any, traversing the link. Thus, the MN can unambiguously localize the failed links by identifying the lost bursts without incurring any alarm dissemination delay. We have proposed several novel m-trail allocation, burst launching time scheduling, and node switch fabric configuration schemes. Numerical results show that the schemes, when deployed in the m-burst framework, are able to localize single-link and multi-link SRLG faults unambiguously, with reasonable fault localization latency, by using at most one WL in each unidirectional link. To reduce the fault localization latency further, we also introduce a novel methodology called nested m-trails. At first, mesh networks are decomposed into cycles and trails. Each cycle (trail) is realized as an independent virtual ring (linear) network using a separate pair of WLs (one WL in each direction) in each undirected link traversed by the cycle (trail). Then, sets of m-trails, i.e., nested m-trails, derived in each virtual network are deployed independently in the m-burst framework for ring (linear) networks. As a result, the fault localization latency is reduced significantly. Moreover, the application of nested m-trails in adaptive probing also reduces the number of sequential probes significantly. Therefore, practical deployment of adaptive probing is now possible. However, the WL consumption of the nested m-trail technique is not limited by one WL per unidirectional link. Thus, further investigation is needed to reduce the WL consumption of the technique.

Tokie regimieji dirgikliai kaip Necker’io gardelė įdomūs tuo, kad yra dviprasmiai bei sukelia trimatės erdvės pokyčio suvokimą. Remiantis suvokimo apkrovos teorija papildoma užduotis turėtų keisti šį suvokimą. Šio darbo tikslas buvo ištirti dviprasmių ir nedviprasmių gardelių suvokimą skirtingos suvokimo apkrovos užduotyse. I eksperimente dalyvavo 18 studentų (9 vyrai ir 9 moterys). Buvo tiriama didelės ir mažos suvokimo apkrovos įtaka reversijų suvokimui. II eksperimente dalyvavo 9 tiriamieji (7 vyrai ir 2 moterys). Tyrimo eiga buvo tokia pati kaip I eksperimento, bet skyrėsi užduotys: vienoje užduotyje raidžių nebuvo (normalus stebėjimas), kitoje užduotyje raidės buvo, bet į jas nereikėjo kreipti dėmesio. Palyginus abiejų tyrimų rezultatus nustatyta, kad bet kokia suvokimo apkrova panaikina Reversijos neigiamumą subjektyvaus pasikeitimo atveju. Realaus pasikeitimo bloke Reversijos neigiamumas buvo gautas, bet nepriklausė nuo apkrovos. Reversijos teigiamumui neturi įtakos nei suvokimo apkrova, nei suvokimo trukdis, tuo tarpu esant suvokimo trukdžiui Reversijos neigiamumas išnyksta tiek realaus, tiek Necker’io gardelės pasikeitimo atvejais. / Ambiguous visual stimuli such as the Necker lattice are interesting because they can cause apparent changes in our perception. According to the perceptual load theory, complementary tasks would be able to modify the amount of attention paid to this perception. The aim of this study was to investigate the perception of ambiguous and unambiguous lattices under different perceptual load tasks. Eighteen participants (9 men) took part in experiment I. The impact of high and low perceptual loads on perception of reversals was studied. 9 subjects (7 men) participated in experiment II. The experimental procedure was the same as in experiment I, but the tasks were a bit different: task without letters (normal observation) and task with letters distracters. Participants were told not to pay attention to letters in experiment II. A comparison of the results of these two experiments revealed that high and low perceptual loads eliminate Reversal Negativity in Necker change condition. Reversal Negativity was found in Real change condition, but it was load-independent. Neither perceptual load, nor load-resembling distractor have any effects on Reversal Positivity, however, Reversal Negativity was suppressed by load-resembling distractors both in Real change and in Necker change conditions.

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Le problème de séparation pour une classe de langages S est le suivant : étant donnés deux langages L1 et L2, existe-t-il un langage appartenant à S qui contient L1, en étant disjoint de L2 ? Si les langages à séparer sont des langages réguliers, le problème de séparation pour la classe S est plus général que le problème de l'appartenance à cette classe, et nous fournit des informations plus détaillées sur la classe. Ce problème de séparation apparaît dans un contexte algébrique sous la forme des parties ponctuelles, et dans un contexte profini sous la forme d'un problème de séparation topologique. Pour quelques classes de langages spécifiques, ce problème a été étudié en utilisant des méthodes profondes de la théorie des semigroupes profinis.Dans cette thèse, on s'intéresse, dans un premier temps, à la décidabilité de ce problème pour plusieurs sous-classes des langages réguliers. Dans un second temps, on s'intéresse à obtenir un langage séparateur, s'il existe, ainsi qu'à la complexité de ces problèmes.Nous établissons une approche générique pour prouver que le problème de séparation est décidable pour une classe de langages donnée. En utilisant cette approche, nous obtenons la décidabilité du problème de séparation pour les langages testables par morceaux, les langages non-ambigus, les langages localement testables, et les langages localement testables à seuil. Ces classes correspondent à des fragments de la logique du premier ordre, et sont parmi lesclasses de langages réguliers les plus étudiées. De plus, cette approche donne une description d'un langage séparateur, pourvu qu'il existe. / The separation problem, for a class S of languages, is the following: given two input languages, does there exist a language in S that contains the first language and that is disjoint from the second langage ?For regular input languages, the separation problem for a class S subsumes the classical membership problem for this class, and provides more detailed information about the class. This separation problem first emerged in an algebraic context in the form of pointlike sets, and in a profinite context as a topological separation problem. These problems have been studied for specific classes of languages, using involved techniques from the theory of profinite semigroups.In this thesis, we are not only interested in showing the decidability of the separation problem for several subclasses of the regular languages, but also in constructing a separating language, if it exists, and in the complexity of these problems.We provide a generic approach, based on combinatorial arguments, to proving the decidability of this problem for a given class. Using this approach, we prove that the separation problem is decidable for the classes of piecewise testable languages, unambiguous languages, and locally (threshold) testable languages. These classes are defined by different fragments of first-order logic, and are among the most studied classes of regular languages. Furthermore, our approach yields a description of a separating language, in case it exists.

Text in English and Arabic / In pre-colonial Africa, the Southwestern Sahara which includes Mauritania, Mali and Senegal belonged to what was then referred to as the Sudan and extended from the Atlantic seaboard to the Red Sea. The advent of Islam and the Arabic language to West Africa in the 11th century heralded an intellectual marathon whose literary output still fascinates us today. At a time when Europe was emerging from the dark ages and Africa was for most Europeans a terra incognita, indigenous African scholars were composing treatises as diverse as mathematics, agriculture and the Islamic sciences. A twentieth century Mauritanian, Arabic monograph, Irshād al- Muqallidīn ʿinda ikhtilāf al-Mujtahidīn1, written circa 1910/1332, by a yet unknown Mauritanian jurist of the Mālikī School, Bāba bin al-Shaykh Sīdī al- Shinqīṭī al-Ntishā-ī (d.1920/1342), a member of the muchacclaimed Shinqīṭī fraternity of scholars, is a fine example of African literary accomplishment. This manuscript hereinafter referred to as the Irshād, is written within the legal framework of Islamic jurisprudence (usūl al-fiqh). A science that relies for the most part on the intellectual and interpretive competence of the independent jurist, or mujtahid, in the application of the methodologies employed in the extraction of legal norms from the primary sources of the sharīʿah. The subject matter of the Irshād deals with the question of juristic differences. Juristic differences invariably arise when a mujtahid exercises his academic freedom to clarify or resolve conundrums in the law and to postulate legal norms. Other independent jurists (mujtahidūn) may posit different legal norms because of the exercise of their individual interpretive skills. These differences, when they are deemed juristically irreconcilable, are called ikhtilāfāt (pl. of ikhtilāf). The author of the Irshād explores a corollary of the ikhtilāf narrative and posits the hypothesis that there ought not to be ikhtilāf in the sharīʿah. The proposed research will comprise an annotated translation of the monograph followed by a synopsis and commentary on its dominant themes. / Religious Studies and Arabic / D. Litt. et Phil. (Islamic Studies)