In this thesis we present new approaches in the domains of soft fault detection and location in complex wire networks, based on the properties of time reversal. When addressing the detection of soft faults, the idea is to adapt the testing signal to the network under test, instead of being predefined for all the tested networks, as opposed to standard reflectometry techniques. We prove that this approach, which we name the Matched Pulse approach (MP), is beneficial whenever the system is more complex, i.e., its response is richer in echoes, which is opposed to common understanding. The MP analysis is conducted via a formal mathematical analysis, followed by simulation and experimental results validating the proposed approach. In the domain of soft fault location, and based on the DORT (Décomposition de l'Opérateur de Retournement Temporel) properties, we derive a distributive non-iterative method able to synthesize signals that focus on the fault position. Through a statistical study we analyze some of the influencing parameters on the performance of the method, and then simulation and experimental results show that the method is able to synthesize signals directly focalizing on the soft fault position, without the need for iterations.

[pt] A literatura tradicional mostra que em mercado desenvolvidos estratégias de reversão de curto prazo no mercado de ações podem ser interpretadas como proxies para provisão de liquidez. Essa dissertação valida esse achado para o cenário brasileiro, um mercado menos líquido e desenvolvido. No mercado americano de ações, o retorno esperado de tais estratégias parece ser lucrativo, variante com o tempo e fortemente previsível usando índices de liquidez e medo tal como o VIX. No Brasil, um mercado mais volátil, a lucratividade de tais estratégias parece ter reduzido nos últimos anos e contrário as expectativas, o EMBImais Brazil é o único índice com poder preditivo sobre os retornos desta estratégia, enquanto o VIX-EWZ e o Ivol-BR, ambos proxies ao que seria um VIX brasileiro não possuem tal poder. O retorno esperado desta estratégia aumenta em momentos de maior percepção de risco, o que indica que a redução na oferta de liquidez, traduzida em um aumento nos retornos esperados pela provisão por liquidez é um dos motivos para evaporação de liquidez em tempos de grandes agitações até mesmo no mercado brasileiro. / [en] Literature shows that short-term reversal strategies in equity markets can be interpreted as a proxy for liquidity provision. This study examines whether the short-term reversal strategy bears similar results in Brazil, a way less developed and illiquid market. On the developed American stock markets, the expected return of such a strategy appears to be lucrative, strongly timevarying and highly predictable with liquidity and fear indexes such as the VIX index. In the Brazilian, more volatile market, the profitability of such a strategy seem to have reduced in the latest years, and contrary to expectations, the EMBIplus Brazil is the only index with predictive power over such returns while the VIX-EWZ and the Ivol-BR, both proxies to what would be a Brazilian VIX have no predictive power. The expected returns of providing liquidity seem to rise in times of increased risk perception, which indicates that withdrawal of liquidity supply, translated in an increase in the expected returns from liquidity provision, is one of the drivers behind the evaporation of liquidity in times of market turmoil even in developing countries.

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.

No description available.

Most modern engines utilise pistons with an offset gudgeon pin. In internal combustion engines, the offset is to the major thrust side of the piston. The piston thrust side is the part of the piston perpendicular to the gudgeon pin that carries the majority of side loading during the power stroke. Primary reason for having the gudgeon pin positioned eccentrically is to prevent the piston from slamming into the cylinder bore after the connecting rod journal passes the top dead centre. This phenomenon is referred to as piston slap, and is more pronounced in compression ignition and high performance engines due to higher combustion pressure than that of commercial spark ignition engines. The coming together of the piston and the bore results in scuffing, at best, or, catastrophic failure at worst. Clearance space between bore and piston is filled by a lubricant film. The main role of the lubricant is to separate the piston and bore by reacting to the applied load. Investigating the above problem requires a holistic approach, whereby a dynamic three degree-of-freedom piston model is coupled with a lubrication model to represent the actual system. The dynamic model determines the motion of the piston in combined axial, lateral and rotation about the gudgeon pin. The reactive forces due to lubricant films on the major and minor thrust sides of the piston play significant roles in piston dynamics and are evaluated by either quasi-static or transient solution of the lubricant contact conjunctions. The novel quasi-static analysis is carried out in the sense of its detailed approach, including many key practical features. not incorporated in other analyses, hitherto reported in literature. These features include first and foremost the development of a specific contact mechanics model for evaluation of conforming contacts for piston skirt against liner or bore. The quasi-static analysis includes many practical feature not encountered in other literature on the subject, such as detailed surface irregularities and modification features, and with thermal distortion. The analysis has been extended to thermohydrodynamics, as well as micro-hydrodynamics, all with high computational mesh densities, and robust methods of solution in space and time domains, including effective influence Newton-Raphson method and linear acceleration integration scheme. The transient tribo-elasto-multi-body dynamics problem includes physics of motion study from film thickness prediction and secondary motion evaluation of the order of micrometers and minutes of arc to large rigid body dynamics, including simultaneous solution of the contact problem at both major and minor thrust sides. Such a comprehensive solution has not hitherto been reported in literature. The thesis discusses many aspects of piston dynamics problem, through the broad spectrum of vehicle manufacture, with many pertinent practical engineering issues. In particular, it provides solutions for high performance Formula 1 racing engines. This is the first ever comprehensive analysis of piston tribodynamics for this range of engines at very high combustion pressures. This study has shown the paramount influence of profile of piston in promoting lubrication between the contiguous bodies, as evident from the pattern of lubricant flow through the contact. Deformation of the bodies increases the volume of lubricant in the contact. During the reversal in direction of piston motion, when the entraining velocity momentarily cases and reversal takes place, the load is held by an elastic squeeze.

International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, Nevada / Predetection recording of spread-spectrum (SS) signals such as GPS transmissions is a desirable objective for both users and developers of equipment designed to receive such signals. (GPS user-equipment development is a lengthy process during which signal simulators are only partially useful.) Upon playback, GPS signals are used by the same or modified receivers so that acquisition, processing, detection and tracking loops can be altered to optimize the receiver parameters. Development of predetect SS signal recording systems is difficult to achieve in practice. Such systems not only must be of suitable phase linearity to preserve the signal content to be extracted but sometimes must also preserve the exact signal-to-noise ratio (SNR) characteristics of the recorded signals. Existing conventional test equipment is unsuitable for deriving value judgments of the quality of a predetect recording system’s output because the SS signal has a negative SNR. This paper reveals that it is possible to use, for this purpose, tape recorders now available on many test ranges in combination with auxiliary equipment similar to that designed for the U.S. Navy’s TRIDENT Program (recording C/A-code data from in-flight missile translators). The basic techniques are described in some detail to enable potential users to understand the necessary equipment concepts and evaluate the author’s approach in terms of their own applications.

Model checking is a fully-automatic formal verification method that has been extremely successful in validating and verifying safety-critical systems in the past three decades. In the past fifteen years, there has been a lot of work in extending many model checking algorithms over finite-state systems to finitely representable infinitestate systems. Unlike in the case of finite systems, decidability can easily become a problem in the case of infinite-state model checking. In this thesis, we present generic and specific techniques that can be used to derive decidability with near-optimal computational complexity for various model checking problems over infinite-state systems. Generic techniques and specific techniques primarily differ in the way in which a decidability result is derived. Generic techniques is a “top-down” approach wherein we start with a Turing-powerful formalismfor infinitestate systems (in the sense of being able to generate the computation graphs of Turing machines up to isomorphisms), and then impose semantic restrictions whereby the desired model checking problem becomes decidable. In other words, to show that a subclass of the infinite-state systems that is generated by this formalism is decidable with respect to the model checking problem under consideration, we will simply have to prove that this subclass satisfies the semantic restriction. On the other hand, specific techniques is a “bottom-up” approach in the sense that we restrict to a non-Turing powerful formalism of infinite-state systems at the outset. The main benefit of generic techniques is that they can be used as algorithmic metatheorems, i.e., they can give unified proofs of decidability of various model checking problems over infinite-state systems. Specific techniques are more flexible in the sense they can be used to derive decidability or optimal complexity when generic techniques fail. In the first part of the thesis, we adopt word/tree automatic transition systems as a generic formalism of infinite-state systems. Such formalisms can be used to generate many interesting classes of infinite-state systems that have been considered in the literature, e.g., the computation graphs of counter systems, Turing machines, pushdown systems, prefix-recognizable systems, regular ground-tree rewrite systems, PAprocesses, order-2 collapsible pushdown systems. Although the generality of these formalisms make most interesting model checking problems (even safety) undecidable, they are known to have nice closure and algorithmic properties. We use these nice properties to obtain several algorithmic metatheorems over word/tree automatic systems, e.g., for deriving decidability of various model checking problems including recurrent reachability, and Linear Temporal Logic (LTL) with complex fairness constraints. These algorithmic metatheorems can be used to uniformly prove decidability with optimal (or near-optimal) complexity of various model checking problems over many classes of infinite-state systems that have been considered in the literature. In fact, many of these decidability/complexity results were not previously known in the literature. In the second part of the thesis, we study various model checking problems over subclasses of counter systems that were already known to be decidable. In particular, we consider reversal-bounded counter systems (and their extensions with discrete clocks), one-counter processes, and networks of one-counter processes. We shall derive optimal complexity of various model checking problems including: model checking LTL, EF-logic, and first-order logic with reachability relations (and restrictions thereof). In most cases, we obtain a single/double exponential reduction in the previously known upper bounds on the complexity of the problems.

This thesis reports on results in the fields of experimental spin- and general wave dynamics.

My thesis covers the details of the development of play Carry Me! and the opportunity I had to explore Anne Bogart's Viewpoints as an approach to devising theatre. I express the challenges, the choices, the process and the presentation of my experience in the project. The subject matter of the script is based on a professional production that failed on Broadway in February of 1968. Carry Me Back to Morningside Heights by Robert Alan Aurthur was Sidney Poitier's directorial debut and starred Louis Gossett, Jr. and Cicely Tyson. The basic plot is a satire about race and role reversal but the overall message to the audience is to promote a better societal understanding of civil rights and cultural differences. My thesis script began with borrowing the premise of the original script but my desire was to make my own artistic choices in developing a new script about race and culture. Through Anne Bogart's Viewpoints process, thirty-seven years of historical distance from the Civil Rights Movement, a clearer understanding of American race relationships and my interest in the style of satire, I wrote and directed Carry Me! as my thesis project.

Seven families of XX and YY homozygous Oreochromis niloticus were produced by mitotic gynogenesis from XY neofemales and their genetic status was verified by multilocus DNA fingerprinting and progeny testing. Two of these gynogenetic families and their corresponding diploid controls were used with 64 AFLP primer combinations in different levels of screening (XX/YY grand pool; XX/YY family pool; XX/YY gynogenetics and XX/XY control individuals) to search for sex-linked or sex-specific markers. Grand pool screening did not reveal any sex-linked markers. Subsequent family pool and individual level screening identified four sex-linked AFLP markers from two primer combinations, three Y-linked (OniY425, OniY382, OniY227) and one X-linked (OniX420). Two of these (OniX420, OniY425) were shown to be allelic. Single locus PCR markers were developed for all of those markers. Linkage analysis of these markers and the sex locus within the source families revealed tight linkage, with estimated map distances of 13cM, 17cM and 20cM for OniY382, OniY227 and OniX420/OniY425 respectively. However, these sex-linked AFLP markers failed to consistently identify sex in unrelated individuals. To develop an effective system for parentage analysis in normal and gynogenetic progeny, AFLPs and multiplexed polymorphic microsatellite loci were investigated. Both were found to be effective, but microsatellites were more appropriate since they are codominant and some loci showed high gene-centromere recombination rates, suitable for discriminating meiotic from mitotic gynogenetics, while AFLPs are dominant markers. Spontaneous diploidization of the maternal chromosome set (SDM) was observed in gynogenetic progeny of one XY neofemale. Maternal inheritance and ploidy status were verified by multilocus DNA fingerprinting and chromosome karyotyping. Close genetic linkage between the red gene and an autosomal sex-reversal gene(s) in gynogenetic progeny and influences of autosomal sex-reversal gene(s) producing males in a fully inbred XX clonal line were previously reported in O. niloticus. To test if the same autosomal sex-reversal locus was responsible in both cases, a series of test crosses was carried out involving XX clonal neomale(s) and homozygous red females. The results indicated the involvement of more than one autosomal sex-reversal locus, one of which is linked to red body colour.