244 research outputs found

    On Internal Merge

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    Generation time statistics of Escherichia coli using synchronous culture techniques

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    The distribution of generation times and the correlation coefficient between the generation times of mother and daughter cells are determined for a B strain of Escherichia coli under various conditions of growth. Synchronously dividing cultures of E. coli are produced by the Mitchison-Vincent density gradient centrifugation technique. Very precise data are yielded by cell number counts at frequent intervals with a Coulter electronic particle counter. Culture growth is followed for three and sometimes four generations. Doubling times between 30 and 80 minutes are obtained at 37°C with mineral salts medium supplemented with suitable carbon sources, namely, glucose + methionine + histidine, glucose, sucrose, glycerol, or succinate. On glucose, doubling times between 40 and 90 minutes are obtained by varying the temperature between 37° and 26°C. A mathematical description of synchronous growth is taken from the literature. The rate of increase of cell number concentration is expressed as the sum of a series of functions with properties related to the generation time distribution of the cells and the correlations between the generation times of related cells. Smoothing of the cell number data by digital filtering and subsequent numerical differentiation yields a series of peaks having little apparent skewness for all growth rates. This is confirmed by fitting a sum of Gaussian functions to the peaks by a nonlinear least squares procedure. The parameters of the generation time distribution and the correlation coefficients between the generation times of parent and progeny cells are then extracted directly from the means and variances of the Gaussian functions. The uncertainty associated with each data point is estimated to be within 1½% and the errors in the extracted parameters are determined by repeated simulation of the data analysis procedure using computer generated noisy data. Under all growth conditions the generation time distribution is of Gaussian form with a coefficient of variation of 0.22 ± 0.02. The mother-daughter generation time correlation coefficient was significantly negative at doubling times between 40 and 64 minutes; a constant value of -0.47 ± 0.06 was consistent with the observations. At doubling times of 30 and 80-90 minutes this coefficient tended to be closer to zero but with a higher uncertainty. In succinate medium at 37°C (doubling time 80 minutes) synchrony was noticeably weaker after the first generation compared with the results at higher growth rates. The growth data for this medium indicate a correlation coefficient very close to zero. The implications of the results are discussed in terms of the predictions of a number of models for the control of cell division that have appeared in the literature

    Fault Diagnosis of Lubrication Decay in Reaction Wheels Using Temperature Estimation and Forecasting via Enhanced Adaptive Particle Filter

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    Reaction wheel (RW), the most common Attitude Control Systems (ACS) in satellites, are highly prone to failure. A satellite needs to be oriented in a particular direction to maneuver and accomplish its mission goals; losing the RW can lead to a complete or partial mission failure. Therefore, estimating the remaining useful life (RUL) in long and short spans can be extremely valuable. The short-period prediction allows the satellite\u27s operator to manage and prioritize mission tasks based on the RUL and increases the chances of a total mission failure becoming a partial one. Studies show that lack of proper bearing lubrication and uneven frictional torque distribution, which lead to variation in motor torque, are the leading causes of failure in RWs. Hence, this study aims to develop a three-step prognostic method for longterm RUL estimation of RWs based on the remaining lubricant for the bearing unit and potential fault in the supplementary lubrication system. In the first step of this method, the temperature of the lubricants is estimated as the non-measurable state of the system, using a proposed Adaptive particle filter (APF) with an-gular velocity and motor current of RW as the available measurements. In the second step, the estimated lubricant\u27s temperature and amount of injected lubrication in the bearing alongside the lubrication degradation model are fed to a two-step Particle Filter (PF) for online model parameter estimation. In the last step, the performance of the proposed prognostics method is evaluated by predicting the RW\u27s RUL under two fault scenarios, including excessive loss of lubrication and insufficient injection of lubrication. The results show promising performance for the proposed scheme with accuracy in estimation of degradation model\u27s parameters around 2–3% of root mean squared percentage error (RMSPE) and prediction of RUL around 0.1- 4% percentage error

    Parameters of Cross-linguistic Variation in Expectation-based Minimalist Grammars (e-MGs)

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    The fact that Parsing and Generation share the same grammatical knowledge is often considered the null hypothesis (Momma and Phillips 2018) but very few algorithms can take advantage of a cognitively plausible incremental procedure that operates roughly in the way words are produced and understood in real time. This is especially difficult if we consider cross-linguistic variation that has a clear impact on word order. In this paper, I present one such formalism, dubbed Expectation-based Minimalist Grammar (e-MG), that qualifies as a simplified version of the (Conflated) Minimalist Grammars, (C)MGs (Stabler 1997, 2011, 2013), and Phase-based Minimalist Grammars, PMGs (Chesi 2005, 2007; Stabler 2011). The crucial simplification consists of driving structure building only using lexically encoded categorial top-down expectations. The commitment to the top-down procedure (in e-MGs and PMGs, as opposed to (C)MGs, ) will be crucial to capture a relevant set of empirical asymmetries in a parameterized cross-linguistic perspective which represents the least common denominator of structure building in both Parsing and Generation

    From transformational grammar to constraint-based approaches

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    Synopsis: This book introduces formal grammar theories that play a role in current linguistic theorizing (Phrase Structure Grammar, Transformational Grammar/Government & Binding, Generalized Phrase Structure Grammar, Lexical Functional Grammar, Categorial Grammar, Head-​Driven Phrase Structure Grammar, Construction Grammar, Tree Adjoining Grammar). The key assumptions are explained and it is shown how the respective theory treats arguments and adjuncts, the active/passive alternation, local reorderings, verb placement, and fronting of constituents over long distances. The analyses are explained with German as the object language. The second part of the book compares these approaches with respect to their predictions regarding language acquisition and psycholinguistic plausibility. The nativism hypothesis, which assumes that humans posses genetically determined innate language-specific knowledge, is critically examined and alternative models of language acquisition are discussed. The second part then addresses controversial issues of current theory building such as the question of flat or binary branching structures being more appropriate, the question whether constructions should be treated on the phrasal or the lexical level, and the question whether abstract, non-visible entities should play a role in syntactic analyses. It is shown that the analyses suggested in the respective frameworks are often translatable into each other. The book closes with a chapter showing how properties common to all languages or to certain classes of languages can be captured.This book is a new edition of http://langsci-press.org/catalog/book/25, http://langsci-press.org/catalog/book/195, http://langsci-press.org/catalog/book/255 , and http://langsci-press.org/catalog/book/287.Fifth revised and extended editio

    A high-performance open-source framework for multiphysics simulation and adjoint-based shape and topology optimization

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    The first part of this thesis presents the advances made in the Open-Source software SU2, towards transforming it into a high-performance framework for design and optimization of multiphysics problems. Through this work, and in collaboration with other authors, a tenfold performance improvement was achieved for some problems. More importantly, problems that had previously been impossible to solve in SU2, can now be used in numerical optimization with shape or topology variables. Furthermore, it is now exponentially simpler to study new multiphysics applications, and to develop new numerical schemes taking advantage of modern high-performance-computing systems. In the second part of this thesis, these capabilities allowed the application of topology optimiza- tion to medium scale fluid-structure interaction problems, using high-fidelity models (nonlinear elasticity and Reynolds-averaged Navier-Stokes equations), which had not been done before in the literature. This showed that topology optimization can be used to target aerodynamic objectives, by tailoring the interaction between fluid and structure. However, it also made ev- ident the limitations of density-based methods for this type of problem, in particular, reliably converging to discrete solutions. This was overcome with new strategies to both guarantee and accelerate (i.e. reduce the overall computational cost) the convergence to discrete solutions in fluid-structure interaction problems.Open Acces

    Head-Driven Phrase Structure Grammar

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    Head-Driven Phrase Structure Grammar (HPSG) is a constraint-based or declarative approach to linguistic knowledge, which analyses all descriptive levels (phonology, morphology, syntax, semantics, pragmatics) with feature value pairs, structure sharing, and relational constraints. In syntax it assumes that expressions have a single relatively simple constituent structure. This volume provides a state-of-the-art introduction to the framework. Various chapters discuss basic assumptions and formal foundations, describe the evolution of the framework, and go into the details of the main syntactic phenomena. Further chapters are devoted to non-syntactic levels of description. The book also considers related fields and research areas (gesture, sign languages, computational linguistics) and includes chapters comparing HPSG with other frameworks (Lexical Functional Grammar, Categorial Grammar, Construction Grammar, Dependency Grammar, and Minimalism)

    Cone Penetration Testing 2022

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    This volume contains the proceedings of the 5th International Symposium on Cone Penetration Testing (CPT’22), held in Bologna, Italy, 8-10 June 2022. More than 500 authors - academics, researchers, practitioners and manufacturers – contributed to the peer-reviewed papers included in this book, which includes three keynote lectures, four invited lectures and 169 technical papers. The contributions provide a full picture of the current knowledge and major trends in CPT research and development, with respect to innovations in instrumentation, latest advances in data interpretation, and emerging fields of CPT application. The paper topics encompass three well-established topic categories typically addressed in CPT events: - Equipment and Procedures - Data Interpretation - Applications. Emphasis is placed on the use of statistical approaches and innovative numerical strategies for CPT data interpretation, liquefaction studies, application of CPT to offshore engineering, comparative studies between CPT and other in-situ tests. Cone Penetration Testing 2022 contains a wealth of information that could be useful for researchers, practitioners and all those working in the broad and dynamic field of cone penetration testing

    Intelligent Transportation Related Complex Systems and Sensors

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    Building around innovative services related to different modes of transport and traffic management, intelligent transport systems (ITS) are being widely adopted worldwide to improve the efficiency and safety of the transportation system. They enable users to be better informed and make safer, more coordinated, and smarter decisions on the use of transport networks. Current ITSs are complex systems, made up of several components/sub-systems characterized by time-dependent interactions among themselves. Some examples of these transportation-related complex systems include: road traffic sensors, autonomous/automated cars, smart cities, smart sensors, virtual sensors, traffic control systems, smart roads, logistics systems, smart mobility systems, and many others that are emerging from niche areas. The efficient operation of these complex systems requires: i) efficient solutions to the issues of sensors/actuators used to capture and control the physical parameters of these systems, as well as the quality of data collected from these systems; ii) tackling complexities using simulations and analytical modelling techniques; and iii) applying optimization techniques to improve the performance of these systems. It includes twenty-four papers, which cover scientific concepts, frameworks, architectures and various other ideas on analytics, trends and applications of transportation-related data

    The evolution of language: Proceedings of the Joint Conference on Language Evolution (JCoLE)

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