Letteratura scientifica selezionata sul tema "Partially observed systems"
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Articoli di riviste sul tema "Partially observed systems"
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Chédor, Sébastien, Christophe Morvan, Sophie Pinchinat e Hervé Marchand. "Analysis of partially observed recursive tile systems". IFAC Proceedings Volumes 45, n. 29 (2012): 265–71. http://dx.doi.org/10.3182/20121003-3-mx-4033.00044.
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Zhou, Changyan, e Ratnesh Kumar. "Bisimilarity Control of Partially Observed Deterministic Systems". IEEE Transactions on Automatic Control 52, n. 9 (settembre 2007): 1642–53. http://dx.doi.org/10.1109/tac.2007.904470.
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Gupta, Deepak, e Sanjib Sabhapandit. "Entropy production for partially observed harmonic systems". Journal of Statistical Mechanics: Theory and Experiment 2020, n. 1 (8 gennaio 2020): 013204. http://dx.doi.org/10.1088/1742-5468/ab54b6.
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Aggoun, Lakhdar, e Lakdere Benkherouf. "FILTERING OF PARTIALLY OBSERVED STOCHASTIC MULTICOMPARTMENTAL SYSTEMS". Stochastic Analysis and Applications 19, n. 2 (27 marzo 2001): 171–82. http://dx.doi.org/10.1081/sap-100001636.
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Achhab, M. E., e S. Cherkaoui. "Stabilization of partially observed stochastic evolution systems". Systems & Control Letters 13, n. 1 (luglio 1989): 73–79. http://dx.doi.org/10.1016/0167-6911(89)90023-6.
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Bertrand, Pierre. "Adaptive control of partially observed linear stochastic systems". Stochastics and Stochastic Reports 54, n. 1-2 (agosto 1995): 21–51. http://dx.doi.org/10.1080/17442509508833997.
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Yip, Paul. "Nonparametric estimation of partially observed stochastic multicompartmental systems". Stochastic Analysis and Applications 5, n. 3 (gennaio 1987): 353–63. http://dx.doi.org/10.1080/07362998708809122.
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Paulin, Daniel, Ajay Jasra, Dan Crisan e Alexandros Beskos. "On concentration properties of partially observed chaotic systems". Advances in Applied Probability 50, n. 2 (giugno 2018): 440–79. http://dx.doi.org/10.1017/apr.2018.21.
Testo completoAbstract (sommario):
AbstractIn this paper we present results on the concentration properties of the smoothing and filtering distributions of some partially observed chaotic dynamical systems. We show that, rather surprisingly, for the geometric model of the Lorenz equations, as well as some other chaotic dynamical systems, the smoothing and filtering distributions do not concentrate around the true position of the signal, as the number of observations tends to ∞. Instead, under various assumptions on the observation noise, we show that the expected value of the diameter of the support of the smoothing and filtering distributions remains lower bounded by a constant multiplied by the standard deviation of the noise, independently of the number of observations. Conversely, under rather general conditions, the diameter of the support of the smoothing and filtering distributions are upper bounded by a constant multiplied by the standard deviation of the noise. To some extent, applications to the three-dimensional Lorenz 63 model and to the Lorenz 96 model of arbitrarily large dimension are considered.
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Cutland, Nigel J., e Tom Lindstr�m. "Random relaxed controls and partially observed stochastic systems". Acta Applicandae Mathematicae 32, n. 2 (agosto 1993): 157–82. http://dx.doi.org/10.1007/bf00998151.
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Imani, Mahdi, e Ulisses M. Braga-Neto. "Particle filters for partially-observed Boolean dynamical systems". Automatica 87 (gennaio 2018): 238–50. http://dx.doi.org/10.1016/j.automatica.2017.10.009.
Testo completoTesi sul tema "Partially observed systems"
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Monsel, Thibault. "Deep Learning for Partially Observed Dynamical Systems". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASG113.
Testo completoAbstract (sommario):
Les équations différentielles partielles (EDP) sont la pierre angulaire de la modélisation des systèmes dynamiques dans diverses disciplines scientifiques. Traditionnellement, les scientifiques utilisent une méthodologie rigoureuse pour interagir avec les processus physiques, collecter des données empiriques et dériver des modèles théoriques. Cependant, même lorsque ces modèles correspondent étroitement aux données observées, ce qui n'est souvent pas le cas, les simplifications nécessaires à l'étude et à la simulation peuvent obscurcir notre compréhension des phénomènes sous-jacents.Cette thèse explore la manière dont les données acquises à partir de systèmes dynamiques peuvent être utilisées pour améliorer et/ou dériver de meilleurs modèles. Le manuscrit se concentre particulièrement sur les dynamiques partiellement observées, où l'état complet du système n'est pas complètement mesuré ou observé. Grâce à la théorie des systèmes partiellement observés, y compris le formalisme de Mori-Zwanzig et le théorème de Takens, nous motivons une structure non-markovienne, en particulier les équations différentielles à retardement (EDR).En combinant le pouvoir d'expression des réseaux neuronaux avec les EDR, nous proposons de nouveaux modèles pour les systèmes partiellement observés. Comme les EDP basées sur les réseaux neuronaux (EDP neuronales) en sont encore à leurs débuts, nous étendons l'état actuel de l'art dans ce domaine en étudiant et en comparant les modèles d'EDP neuronales avec des types de retard arbitraires connus a-priori à travers une variété de systèmes dynamiques. Ces références incluent des systèmes avec des retards dépendant du temps et de l'état. Sur la base de ces études, nous explorons ensuite la paramétrisation des retards constants dans les EDP neuronales. Nos résultats démontrent que l'introduction de retards constants pouvant être appris, par opposition à des configurations de retards fixes, permet d'améliorer les performances globales de la modélisation et de l'ajustement des systèmes dynamiques.Nous appliquons ensuite les EDP neurales non markoviennes avec des retards constants pouvant être appris à la modélisation de la fermeture et de la correction des systèmes dynamiques, en démontrant une meilleure précision à long terme par rapport aux termes des équations différentielles ordinaires. Enfin, nous explorons l'utilisation des EDR neuronales dans le contexte de la commande prédictive de modèle pour le contrôle des systèmes dynamiquesPartial Differential Equations (PDEs) are the cornerstone of modeling dynamical systems across various scientific disciplines. Traditionally, scientists employ a rigorous methodology to interact with physical processes, collect empirical data, and derive theoretical models. However, even when these models align closely with observed data, which is often not the case, the necessary simplifications made for study and simulation can obscure our understanding of the underlying phenomena.This thesis explores how data acquired from dynamical systems can be utilized to improve and/or derive better models. The manuscript focuses particularly on partially observed dynamics, where the system's full state is not completely measured or observed. Through the theory of partially observed systems, including the Mori-Zwanzig formalism and Takens' theorem, we motivate a non-Markovian structure, specifically Delay Differential Equations (DDEs).By combining the expressive power of neural networks with DDEs, we propose novel models for partially observed systems. As neural network-based DDEs (Neural DDEs) are still in their infancy, we extend the current state of the art in this field by studying and benchmarking Neural DDE models with a-priori known arbitrary delay types across a variety of dynamical systems. These benchmarks include systems, with time-dependent and state-dependent delays. Building upon these investigations, we then explore the parameterization of constant delays in Neural DDEs. Our findings demonstrate that introducing learnable constant delays, as opposed to fixed delay configurations, results in improved overall performance in dynamical system modeling and fitting.We then apply the non-Markovian Neural DDEs with learnable constant delays to dynamical system closure and correction modeling, demonstrating improved long-term accuracy compared to Ordinary Differential Equation terms. Lastly, we explore the use of Neural DDEs in the context of Model Predictive Control (MPC) for controlling dynamical systems
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YOU, DAN. "Supervisory Control and Analysis of Partially-observed Discrete Event Systems". Doctoral thesis, Università degli Studi di Cagliari, 2021. http://hdl.handle.net/11584/308984.
Testo completoAbstract (sommario):
Nowadays, a variety of real-world systems fall into discrete event systems (DES). In practical scenarios, due to facts like limited sensor technique, sensor failure, unstable network and even the intrusion of malicious agents, it might occur that some events are unobservable, multiple events are indistinguishable in observations, and observations of some events are nondeterministic. By considering various practical scenarios, increasing attention in the DES community has been paid to partially-observed DES, which in this thesis refer broadly to those DES with partial and/or unreliable observations.
In this thesis, we focus on two topics of partially-observed DES, namely, supervisory control and analysis.
The first topic includes two research directions in terms of system models. One is the supervisory control of DES with both unobservable and uncontrollable events, focusing on the forbidden state problem; the other is the supervisory control of DES vulnerable to sensor-reading disguising attacks (SD-attacks), which is also interpreted as DES with nondeterministic observations, addressing both the forbidden state problem and the liveness-enforcing problem. Petri nets (PN) are used as a reference formalism in this topic. First, we study the forbidden state problem in the framework of PN with both unobservable and uncontrollable transitions, assuming that unobservable transitions are uncontrollable. For ordinary PN subject to an admissible Generalized Mutual Exclusion Constraint (GMEC), an optimal on-line control policy with polynomial complexity is proposed provided that a particular subnet, called observation subnet, satisfies certain conditions in structure. It is then discussed how to obtain an optimal on-line control policy for PN subject to an arbitrary GMEC. Next, we still consider the forbidden state problem but in PN vulnerable to SD-attacks. Assuming the control specification in terms of a GMEC, we propose three methods to derive on-line control policies. The first two lead to an optimal policy but are computationally inefficient for large-size systems, while the third method computes a policy with timely response even for large-size systems but at the expense of optimality. Finally, we investigate the liveness-enforcing problem still assuming that the system is vulnerable to SD-attacks. In this problem, the plant is modelled as a bounded PN, which allows us to off-line compute a supervisor starting from constructing the reachability graph of the PN. Then, based on repeatedly computing a more restrictive liveness-enforcing supervisor under no attack and constructing a basic supervisor, an off-line method that synthesizes a liveness-enforcing supervisor tolerant to an SD-attack is proposed.
In the second topic, we care about the verification of properties related to system security. Two properties are considered, i.e., fault-predictability and event-based opacity. The former is a property in the literature, characterizing the situation that the occurrence of any fault in a system is predictable, while the latter is a newly proposed property in the thesis, which describes the fact that secret events of a system cannot be revealed to an external observer within their critical horizons. In the case of fault-predictability, DES are modeled by labeled PN. A necessary and sufficient condition for fault-predictability is derived by characterizing the structure of the Predictor Graph. Furthermore, two rules are proposed to reduce the size of a PN, which allow us to analyze the fault-predictability of the original net by verifying that of the reduced net. When studying event-based opacity, we use deterministic finite-state automata as the reference formalism. Considering different scenarios, we propose four notions, namely, K-observation event-opacity, infinite-observation event-opacity, event-opacity and combinational event-opacity. Moreover, verifiers are proposed to analyze these properties.
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Agrawal, Rakshita. "Planning and scheduling problems in manufacturing systems with high degree of resource degradation". Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34767.
Testo completoAbstract (sommario):
The term resource is used to refer to a machine, tool-group, piece of equipment or personnel. Optimization models for resource maintenance are obtained in conjunction with other production related decisions like production planning, production scheduling, resource allocation and job inspection. Emphasis is laid on integrating the above inter-dependent decisions into a unified optimization framework. This is accomplished for large stationary resources, small non-stationary resources with high breaking rate and for resources that form a part of a network.
Owing to large problem size and high uncertainty, the optimal decisions are determined by formulating and solving the above problems as Markov decision processes (MDPs). Approximate dynamic programming based algorithms are used for solving the large optimization problems at hand. The performance of resulting near optimal policies is compared with that of traditional formulations in all cases. The latter treat the resource maintenance decisions independent of other manufacturing related decisions.
In certain formulations, the resource state is not completely observable. This results in a partially observable MDP (POMDP). An alternative algorithm for the solution of POMDP is developed, where several mixed integer linear programs (MILPs) are solved during each ADP iteration. This helps obtain better quality solutions for the POMDPs with very large or continuous action spaces in an efficient manner.
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Liu, Chenguang. "Statistical inference for a partially observed interacting system of Hawkes processes". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS203.
Testo completoAbstract (sommario):
Nous observons les actions d'un sous-échantillon de K de N d’individus, pendant un intervalle de temps de longueur t>0, pour certaines grandes K≤N. Nous modélisons les relations des individus par i.i.d. Bernoulli (p) variables aléatoires, où p∈(0,1] est un paramètre inconnu. Le taux d’action de chaque individu dépend d’un paramètre inconnu μ>0 et sur la somme de quelque fonction ϕ des âges des actions des individus qui l'influencent. La fonction ϕ est inconnue mais nous supposons qu'elle se désintègre rapidement. Le but de cette thèse est d'estimer le paramètre p, qui est la principale caractéristique du graphe d’interaction, dans l'asymptotique où taille de la population N→∞, la taille de la population observée K→∞, et dans un temps long t→∞. Soit mt le nombre moyen d'actions par individu jusqu'au temps t, qui dépend de tous les paramètres du modèle. Dans le cas sous-critique, où mt augmente linéairement, nous construisons un estimateur de p avec le taux de convergence 1K√+NmtK√+NKmt√. Dans le cas supercritique, où mt augmente rapidement de façon exponentielle, nous construisons un estimateur de p avec le taux de convergence 1K√+NmtK√. Dans un second temps, nous étudions la normalité asymptotique de ces estimateurs. Dans le cas sous-critique, le travail est très technique mais assez général, et nous sommes amenés à étudier trois régimes possibles, en fonction du terme dominant dans 1K√+NmtK√+NKmt√ à 0. Dans le cas supercritique, nous supposons malheureusement quelques conditions supplémentaires et considérons seulement l'un des deux régimes possiblesWe observe the actions of a K sub-sample of N individuals, during some time interval with length t>0, for some large K≤N. We model the relationships of individuals by i.i.d. Bernoulli(p) random variables, where p∈(0,1] is an unknown parameter. The rate of action of each individual depends on some unknown parameter μ>0 and on the sum of some function ϕ of the ages of the actions of the individuals which influence him. The function ϕ is unknown but we assume it rapidly decays. The aim of this thesis is to estimate the parameter p, which is the main characteristic of the interaction graph, in the asymptotic where the population size N→∞, the observed population size K→∞, and in large time t→∞. Let mt be the average number of actions per individual up to time t, which depends on all the parameters of the model. In the subcritical case, where mt increases linearly, we build an estimator of p with the rate of convergence \frac{1}{\sqrt{K}}+\frac{N} m_t\sqrt{K}}+\frac{N}{K\sqrt{m_t}}. In the supercritical case, where mt increases exponentially fast, we build an estimator of p with the rate of convergence 1K√+NmtK√. In a second time, we study the asymptotic normality of those estimators. In the subcritical case, the work is very technical but rather general, and we are led to study three possible regimes, depending on the dominating term in 1K√+NmtK√+NKmt√→0. In the supercritical case, we, unfortunately, suppose some additional conditions and consider only one of the two possible regimes
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Kahelras, Mohamed. "Conception d'observateurs pour différentes classes de systèmes à retards non linéaires". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS005/document.
Testo completoAbstract (sommario):
Le retard est un phénomène naturel présent dans la majorité des systèmes physiques et dans les applications d’ingénierie, ainsi, les systèmes à retard ont été un domaine de recherche très actif en automatique durant les 60 dernières années. La conception d’observateur est un des sujets les plus importants qui a été étudié, ceci est dû à l’importance des observateurs en automatique et dans les systèmes de commande en absence de capteur pour mesurer une variable. Dans ce travail, l’objectif principal est de concevoir des observateurs pour différentes classes de systèmes à retard avec un retard arbitrairement large, et ce en utilisant différentes approches. Dans la première partie de cette thèse, la conception d’un observateur a été réalisée pour une classe de systèmes non linéaires triangulaires avec une sortie échantillonnée et un retard arbitraire. Une l’autre difficulté majeure avec cette classe de systèmes est le fait que la matrice d’état dépend du signal de sortie non-retardé qui est immesurable. Un nouvel observateur en chaine, composé de sous-observateurs en série est conçu pour compenser les retards arbitrairement larges. Dans la seconde partie de ce travail, un nouvel observateur a été conçu pour un autre type de systèmes non linéaires triangulaires, où le retard a été considéré, cette fois-ci, comme une équation aux dérivées partielles de type hyperbolique du premier ordre. La transformation inverse en backstepping et le concept de l’observateur en chaine ont été utilisés lors de la conception de cet observateur afin d’assurer son efficacité en cas de grands retards. Dans la dernière partie de cette thèse, la conception d’un nouvel observateur a été réalisée pour un type de système modélisé par des équations paraboliques non linéaires où les mesures sont issues d’un nombre fini de points du domaine spatial. Cet observateur est constitué d’une série de sous-observateurs en chaine. Chaque sous-observateur compense une fraction du retard global. L'analyse de la stabilité des systèmes d’erreur a été fondée sur différentes fonctionnelles Lyapunov-Krasovskii. Par ailleurs, différents instruments mathématiques ont été employés au cours des différentes preuves présentées. Les résultats de simulation ont été présentés dans le but de confirmer l'exactitude des résultats théoriquesTime-delay is a natural phenomenon that is present in most physical systems and engineering applications, thus, delay systems have been an active area of research in control engineering for more than 60 years. Observer design is one of the most important subject that has been dealt with, this is due to the importance of observers in control engineering systems not only when sensing is not sufficient but also when a sensing reliability is needed. In this work, the main goal was to design observers for different classes of nonlinear delayed systems with an arbitrary large delay, using different approaches. In the first part, the problem of observer design is addressed for a class of triangular nonlinear systems with not necessarily small delay and sampled output measurements. Another major difficulty with this class of systems is the fact that the state matrix is dependent on the un-delayed output signal which is not accessible to measurement. A new chain observer, composed of sub-observers in series, is designed to compensate for output sampling and arbitrary large delays.In the second part of this work, another kind of triangular nonlinear delayed systems was considered, where this time the delay was considered as a first order hyperbolic partial differential equation. The inverse backstepping transformation was invoked and a chain observer was developed to ensure its effectiveness in case of large delays. Finally, a new observer was designed for a class of nonlinear parabolic partial differential equations under point measurements, in the case of large delays. The observer was composed of several chained sub-observers. Each sub-observer compensates a fraction of the global delay. The stability analyses of the error systems were based on different Lyapunov-Krasovskii functionals. Also different mathematical tools have been used in order to prove the results. Simulation results were presented to confirm the accuracy of the theoretical results
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Li, Xiaodong. "Observation et commande de quelques systèmes à paramètres distribués". Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00456850.
Testo completoAbstract (sommario):
L'objectif principal de cette thèse consiste à étudier plusieurs thématiques : l'étude de l'observation et la commande d'un système de structure flexible et l'étude de la stabilité asymptotique d'un système d'échangeurs thermiques. Ce travail s'inscrit dans le domaine du contrôle des systèmes décrits par des équations aux dérivées partielles (EDP). On s'intéresse au système du corps-poutre en rotation dont la dynamique est physiquement non mesurable. On présente un observateur du type Luenberger de dimension infinie exponentiellement convergent afin d'estimer les variables d'état. L'observateur est valable pour une vitesse angulaire en temps variant autour d'une constante. La vitesse de convergence de l'observateur peut être accélérée en tenant compte d'une seconde étape de conception. La contribution principale de ce travail consiste à construire un simulateur fiable basé sur la méthode des éléments finis. Une étude numérique est effectuée pour le système avec la vitesse angulaire constante ou variante en fonction du temps. L'influence du choix de gain est examinée sur la vitesse de convergence de l'observateur. La robustesse de l'observateur est testée face à la mesure corrompue par du bruit. En mettant en cascade notre observateur et une loi de commande stabilisante par retour d'état, on souhaite obtenir une stabilisation globale du système. Des résultats numériques pertinents permettent de conjecturer la stabilité asymptotique du système en boucle fermée. Dans la seconde partie, l'étude est effectuée sur la stabilité exponentielle des systèmes d'échangeurs thermiques avec diffusion et sans diffusion. On établit la stabilité exponentielle du modèle avec diffusion dans un espace de Banach. Le taux de décroissance optimal du système est calculé pour le modèle avec diffusion. On prouve la stabilité exponentielle dans l'espace Lp pour le modèle sans diffusion. Le taux de décroissance n'est pas encore explicité dans ce dernier cas.
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Shi, Ruixia. "Partially observed inventory systems /". 2009. http://proquest.umi.com/pqdweb?did=1899484871&sid=6&Fmt=2&clientId=10361&RQT=309&VName=PQD.
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Hsu, Shun-pin. "Discrete-time partially observed Markov decision processes ergodic, adaptive, and safety control /". Thesis, 2002. http://wwwlib.umi.com/cr/utexas/fullcit?p3110619.
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"A Machine Learning based High-Speed State Estimator for Partially Observed Electric Transmission Systems". Master's thesis, 2020. http://hdl.handle.net/2286/R.I.63057.
Testo completoAbstract (sommario):
abstract: The accurate monitoring of the bulk transmission system of the electric power grid by sensors, such as Remote Terminal Units (RTUs) and Phasor Measurement Units (PMUs), is essential for maintaining the reliability of the modern power system. One of the primary objectives of power system monitoring is the identification of the snapshots of the system at regular intervals by performing state estimation using the available measurements from the sensors. The process of state estimation corresponds to the estimation of the complex voltages at all buses of the system. PMU measurements play an important role in this regard, because of the time-synchronized nature of these measurements as well as the faster rates at which they are produced. However, a model-based linear state estimator created using PMU-only data requires complete observability of the system by PMUs for its continuous functioning. The conventional model-based techniques also make certain assumptions in the modeling of the physical system, such as the constant values of the line parameters. The measurement error models in the conventional state estimators are also assumed to follow a Gaussian distribution. In this research, a data mining technique using Deep Neural Networks (DNNs) is proposed for performing a high-speed, time-synchronized state estimation of the transmission system of the power system. The proposed technique uses historical data to identify the correlation between the measurements and the system states as opposed to directly using the physical model of the system. Therefore, the highlight of the proposed technique is its ability to provide an accurate, fast, time-synchronized estimate of the system states even in the absence of complete system observability by PMUs.
The state estimator is formulated for the IEEE 118-bus system and its reliable performance is demonstrated in the presence of redundant observability, complete observability, and incomplete observability. The robustness of the state estimator is also demonstrated by performing the estimation in presence of Non-Gaussian measurement errors and varying line parameters. The consistency of the DNN state estimator is demonstrated by performing state estimation for an entire day.Dissertation/Thesis
Masters Thesis Electrical Engineering 2020
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CHEN, JIA-XI, e 陳家熙. "Robotic vision system with two dimensional recognition and positioning of partially observed objects". Thesis, 1988. http://ndltd.ncl.edu.tw/handle/62818552294949823527.
Testo completoLibri sul tema "Partially observed systems"
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Whiting, Ralph Gerard. Quality monitoring in manufacturing systems: a partially observed Markov chain approach. 1985.
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Mashhoon, Bahram. Nonlocal Gravity. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198803805.001.0001.
Testo completoAbstract (sommario):
A postulate of locality permeates through the special and general theories of relativity. First, Lorentz invariance is extended in a pointwise manner to actual, namely, accelerated observers in Minkowski spacetime. This hypothesis of locality is then employed crucially in Einstein’s local principle of equivalence to render observers pointwise inertial in a gravitational field. Field measurements are intrinsically nonlocal, however. To go beyond the locality postulate in Minkowski spacetime, the past history of the accelerated observer must be taken into account in accordance with the Bohr-Rosenfeld principle. The observer in general carries the memory of its past acceleration. The deep connection between inertia and gravitation suggests that gravity could be nonlocal as well and in nonlocal gravity the fading gravitational memory of past events must then be taken into account. Along this line of thought, a classical nonlocal generalization of Einstein’s theory of gravitation has recently been developed. In this nonlocal gravity (NLG) theory, the gravitational field is local, but satisfies a partial integro-differential field equation. A significant observational consequence of this theory is that the nonlocal aspect of gravity appears to simulate dark matter. The implications of NLG are explored in this book for gravitational lensing, gravitational radiation, the gravitational physics of the Solar System and the internal dynamics of nearby galaxies as well as clusters of galaxies. This approach is extended to nonlocal Newtonian cosmology, where the attraction of gravity fades with the expansion of the universe. Thus far only some of the consequences of NLG have been compared with observation.
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Ben-Porat, Guy. Secularization in Israel. A cura di Phil Zuckerman e John R. Shook. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199988457.013.11.
Testo completoAbstract (sommario):
Neither the study of the political system nor surveys of individual religiosity capture the full picture of secularization in Israel. The power of religious parties seems unshaken, and formal changes in religious policies and legislation are few. A large number of Israelis maintain their attachment to Jewish religion in beliefs and practices, and the Jewish majority agrees that Israel is and must remain a “Jewish state.” However, economic and demographic trends in the past two decades have caused incremental changes, not registered in formal political channels, toward the partial yet significant secularization of Israel. Religion still has a hold on private beliefs and practices, but secularization will unfold in societal changes involving a decline of religious authority over significant spheres of life. A more complex concept of secularization allows for contradictions observed in Israel and helps to explain how secularization can occur while religion remains embedded in state and society.
Capitoli di libri sul tema "Partially observed systems"
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Kutoyants, Yu. "Partially Observed Systems". In Identification of Dynamical Systems with Small Noise, 192–216. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1020-4_7.
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Müller, Ursula U., Anton Schick e Wolfgang Wefelmeyer. "Estimators for Partially Observed Markov Chains". In Statistical Models and Methods for Biomedical and Technical Systems, 419–33. Boston, MA: Birkhäuser Boston, 2008. http://dx.doi.org/10.1007/978-0-8176-4619-6_29.
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Saldi, Naci, Tamás Linder e Serdar Yüksel. "Approximations for Partially Observed Markov Decision Processes". In Systems & Control: Foundations & Applications, 99–123. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-79033-6_5.
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Eftekhar Azam, Saeed. "Recursive Bayesian Estimation of Partially Observed Dynamic Systems". In Online Damage Detection in Structural Systems, 7–55. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-02559-9_2.
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De Leeuw, Jan. "Least Squares Optimal Scaling of Partially Observed Linear Systems". In Mathematical Modelling: Theory and Applications, 121–34. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-1958-6_7.
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Zhao, Sinong, Zhaoyang Yu, Xiaofei Wang, Trent G. Marbach, Gang Wang e Xiaoguang Liu. "Meta Pseudo Labels for Anomaly Detection via Partially Observed Anomalies". In Database Systems for Advanced Applications, 100–109. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-30678-5_8.
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Bertrand, Pierre. "Adaptive control of partially observed linear systems, the scalar case". In Stochastic Theory and Adaptive Control, 40–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/bfb0113230.
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Lafortune, Stéphane, Kurt Rohloff e Tae-Sic Yoo. "Recent Advances on the Control of Partially-Observed Discrete-Event Systems". In Synthesis and Control of Discrete Event Systems, 3–17. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4757-6656-1_1.
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Kim, Jin Won, e Sebastian Reich. "On Forward–Backward SDE Approaches to Conditional Estimation". In Mathematics of Planet Earth, 115–36. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-70660-8_6.
Testo completoAbstract (sommario):
AbstractIn this chapter, we investigate the representation of conditional expectation values for partially observed diffusion processes in terms of appropriate estimators. The work of Kalman and Bucy has established a duality between filtering and estimation in the context of time-continuous linear systems. This duality has recently been extended to time-continuous nonlinear systems in terms of an optimization problem constrained by a backward stochastic partial differential equation. Here we revisit this problem from the perspective of appropriate forward-backward stochastic differential equations. Our approach sheds new light on the conditional estimation problem and provides a unifying perspective. It is also demonstrated that certain formulations of the estimation problem lead to deterministic formulations similar to the linear Gaussian case as originally investigated by Kalman and Bucy. Finally, we discuss an application of the proposed formulation to optimal control problem on partially observed diffusion processes.
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Camargo, Manuel, Marlon Dumas e Oscar González-Rojas. "Learning Accurate Business Process Simulation Models from Event Logs via Automated Process Discovery and Deep Learning". In Advanced Information Systems Engineering, 55–71. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-07472-1_4.
Testo completoAbstract (sommario):
AbstractBusiness process simulation is a well-known approach to estimate the impact of changes to a process with respect to time and cost measures – a practice known as what-if process analysis. The usefulness of such estimations hinges on the accuracy of the underlying simulation model. Data-Driven Simulation (DDS) methods leverage process mining techniques to learn process simulation models from event logs. Empirical studies have shown that, while DDS models adequately capture the observed sequences of activities and their frequencies, they fail to accurately capture the temporal dynamics of real-life processes. In contrast, generative Deep Learning (DL) models are better able to capture such temporal dynamics. The drawback of DL models is that users cannot alter them for what-if analysis due to their black-box nature. This paper presents a hybrid approach to learn process simulation models from event logs wherein a (stochastic) process model is extracted via DDS techniques, and then combined with a DL model to generate timestamped event sequences. An experimental evaluation shows that the resulting hybrid simulation models match the temporal accuracy of pure DL models, while partially retaining the what-if analysis capability of DDS approaches.
Atti di convegni sul tema "Partially observed systems"
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Ping, Xu, Rich Burton e Colin Sargent. "Identifying a Nonlinear Dynamic System With Partially Recurrent Neural Networks: Feasibility Study and Issues on Error Accumulation Problems". In ASME 1997 International Mechanical Engineering Congress and Exposition, 13–19. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1276.
Testo completoAbstract (sommario):
Abstract Conventional methods of modeling transient behavior of an actual system involve developing mathematical equations based on the observed physical relationships among the associated components and engineering practical considerations. In many cases, however, the presence of nonlinearities in actual systems and the difficulties in accurately measuring parameters have restricted the interpretation of the modeling results to specific operating points and or with limited modeling accuracy. An alternate is to establish the mathematical relationships of a system using a system identification approach based on input-output observations. Neural networks show the potential of establishing these mathematical relationships, because of their proven capability of approximating nonlinear functions. This study investigates the use of partially recurrent neural networks to identify transient responses of certain nonlinear systems, and presents the results of a theoretical study which carefully examines the modeling error behavior. The results of this study have established the potential and, indeed limitations to this neural modeling approach. The effect of error accumulation through feedback paths of dynamic models on the modeling accuracy is briefly discussed with an illustrative example.
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Imani, Mahdi, e Seyede Fatemeh Ghoreishi. "Partially-Observed Discrete Dynamical Systems". In 2021 American Control Conference (ACC). IEEE, 2021. http://dx.doi.org/10.23919/acc50511.2021.9483049.
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Dion, Jean-Luc, Fatma Abid, Gaël Chevallier, Hugo Festjens, Nicolas Peyret, Franck Renaud, Moustafa Seifeddine e Cyrille Stephan. "Compact Model Synthesis for Partially Observed Operational Systems". In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12111.
Testo completoAbstract (sommario):
This work proposes a Compact Model Synthesis (CMS) for Partially Observed Operational Systems (POOS) without using the complete knowledge of models. Series of “grey boxes” fed with partial observations are built in order to synthesize target variables with compact models. The recursive process for real time computation is based on Kalman Filters (KF). This stochastic approach allows to converge in line toward deterministic models with estimated uncertainties and without intrusion on the complete model process. Mathematical context is described first and illustrated secondly with two examples.
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Subramanian, Jayakumar, e Aditya Mahajan. "Approximate information state for partially observed systems". In 2019 IEEE 58th Conference on Decision and Control (CDC). IEEE, 2019. http://dx.doi.org/10.1109/cdc40024.2019.9029898.
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Doddi, Harish, Deepjyoti Deka e Murti Salapaka. "Learning partially observed meshed distribution grids". In 2020 International Conference on Probabilistic Methods Applied to Power Systems (PMAPS). IEEE, 2020. http://dx.doi.org/10.1109/pmaps47429.2020.9183648.
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Wang, Ran, Raman Goyal, Suman Chakravorty e Robert E. Skelton. "Data-based Control of Partially-Observed Robotic Systems". In 2021 IEEE International Conference on Robotics and Automation (ICRA). IEEE, 2021. http://dx.doi.org/10.1109/icra48506.2021.9561001.
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Zhang, Qi, Zhiwu Li, Carla Seatzu e Alessandro Giua. "Stealthy Attacks for Partially-Observed Discrete Event Systems". In 2018 IEEE 23rd International Conference on Emerging Technologies and Factory Automation (ETFA). IEEE, 2018. http://dx.doi.org/10.1109/etfa.2018.8502501.
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Mahajan, Aditya. "Approximate Planning and Learning for Partially Observed Systems". In The 7th International Conference of Control, Dynamic Systems, and Robotics. Avestia Publishing, 2020. http://dx.doi.org/10.11159/cdsr20.03.
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Yang, Chun, Yaakov Bar-Shalom e Ching Fang Lin. "Control of Partially Observed Discrete-Time Jump Systems". In 1991 American Control Conference. IEEE, 1991. http://dx.doi.org/10.23919/acc.1991.4791641.
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Ammour, R., E. Leclercq, E. Sanlaville e D. Lefebvre. "Faults prognosis using partially observed stochastic Petri nets". In 2016 13th International Workshop on Discrete Event Systems (WODES). IEEE, 2016. http://dx.doi.org/10.1109/wodes.2016.7497890.
Testo completoRapporti di organizzazioni sul tema "Partially observed systems"
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Baras, J. S., e A. Bensoussan. On Observer Problems for Systems Governed by Partial Differential Equations. Fort Belvoir, VA: Defense Technical Information Center, luglio 1987. http://dx.doi.org/10.21236/ada187430.
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Wong, Eric A., e Zehava Uni. Nutrition of the Developing Chick Embryo: Nutrient Uptake Systems of the Yolk Sac Membrane and Embryonic Intestine. United States Department of Agriculture, giugno 2012. http://dx.doi.org/10.32747/2012.7697119.bard.
Testo completoAbstract (sommario):
We have examined the developmental changes in composition, amount, and uptake of yolk nutrients (fat, protein, water and carbohydrates) and the expression ofnutrient transporters in the yolk sac membrane (YSM) from embryonic day 11 (Ell) to 21 (E21) and small intestine from embryonic day 15 (E15) to E21 in embryos from young (22-25 wk) and old (45-50 wk) Cobb and Leghorn breeder flocks. The developmental expression profiles for the peptide transporter 1 (PepTl), the amino acid transporters, EAAT3, CAT-1 and BOAT, the sodium glucose transporter (SGLTl), the fructose transporter (GLUT5), the digestive enzymes aminopeptidase N (APN) and sucraseisomaltase (SI) were assayed by the absolute quantification real time PCR method in the YSM and embryonic intestine. Different temporal patterns of expression were observed for these genes. The effect of in ovo injection of peptides (the dipeptide Gly-Sar, purified peptides, trypsin hydrolysate) on transporter gene expression has been examined in the embryonic intestine. Injection of a partial protein hydrolysate resulted in an increase in expression of the peptide transporter PepT2. We have initiated a transcriptome analysis of genes expressed in the YSM at different developmental ages to better understand the function of the YSM.
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Daudelin, Francois, Lina Taing, Lucy Chen, Claudia Abreu Lopes, Adeniyi Francis Fagbamigbe e Hamid Mehmood. Mapping WASH-related disease risk: A review of risk concepts and methods. United Nations University Institute for Water, Environment and Health, dicembre 2021. http://dx.doi.org/10.53328/uxuo4751.
Testo completoAbstract (sommario):
The report provides a review of how risk is conceived of, modelled, and mapped in studies of infectious water, sanitation, and hygiene (WASH) related diseases. It focuses on spatial epidemiology of cholera, malaria and dengue to offer recommendations for the field of WASH-related disease risk mapping. The report notes a lack of consensus on the definition of disease risk in the literature, which limits the interpretability of the resulting analyses and could affect the quality of the design and direction of public health interventions. In addition, existing risk frameworks that consider disease incidence separately from community vulnerability have conceptual overlap in their components and conflate the probability and severity of disease risk into a single component. The report identifies four methods used to develop risk maps, i) observational, ii) index-based, iii) associative modelling and iv) mechanistic modelling. Observational methods are limited by a lack of historical data sets and their assumption that historical outcomes are representative of current and future risks. The more general index-based methods offer a highly flexible approach based on observed and modelled risks and can be used for partially qualitative or difficult-to-measure indicators, such as socioeconomic vulnerability. For multidimensional risk measures, indices representing different dimensions can be aggregated to form a composite index or be considered jointly without aggregation. The latter approach can distinguish between different types of disease risk such as outbreaks of high frequency/low intensity and low frequency/high intensity. Associative models, including machine learning and artificial intelligence (AI), are commonly used to measure current risk, future risk (short-term for early warning systems) or risk in areas with low data availability, but concerns about bias, privacy, trust, and accountability in algorithms can limit their application. In addition, they typically do not account for gender and demographic variables that allow risk analyses for different vulnerable groups. As an alternative, mechanistic models can be used for similar purposes as well as to create spatial measures of disease transmission efficiency or to model risk outcomes from hypothetical scenarios. Mechanistic models, however, are limited by their inability to capture locally specific transmission dynamics. The report recommends that future WASH-related disease risk mapping research: - Conceptualise risk as a function of the probability and severity of a disease risk event. Probability and severity can be disaggregated into sub-components. For outbreak-prone diseases, probability can be represented by a likelihood component while severity can be disaggregated into transmission and sensitivity sub-components, where sensitivity represents factors affecting health and socioeconomic outcomes of infection. -Employ jointly considered unaggregated indices to map multidimensional risk. Individual indices representing multiple dimensions of risk should be developed using a range of methods to take advantage of their relative strengths. -Develop and apply collaborative approaches with public health officials, development organizations and relevant stakeholders to identify appropriate interventions and priority levels for different types of risk, while ensuring the needs and values of users are met in an ethical and socially responsible manner. -Enhance identification of vulnerable populations by further disaggregating risk estimates and accounting for demographic and behavioural variables and using novel data sources such as big data and citizen science. This review is the first to focus solely on WASH-related disease risk mapping and modelling. The recommendations can be used as a guide for developing spatial epidemiology models in tandem with public health officials and to help detect and develop tailored responses to WASH-related disease outbreaks that meet the needs of vulnerable populations. The report’s main target audience is modellers, public health authorities and partners responsible for co-designing and implementing multi-sectoral health interventions, with a particular emphasis on facilitating the integration of health and WASH services delivery contributing to Sustainable Development Goals (SDG) 3 (good health and well-being) and 6 (clean water and sanitation).
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Elbaum, Michael, e Peter J. Christie. Type IV Secretion System of Agrobacterium tumefaciens: Components and Structures. United States Department of Agriculture, marzo 2013. http://dx.doi.org/10.32747/2013.7699848.bard.
Testo completoAbstract (sommario):
Objectives: The overall goal of the project was to build an ultrastructural model of the Agrobacterium tumefaciens type IV secretion system (T4SS) based on electron microscopy, genetics, and immunolocalization of its components. There were four original aims: Aim 1: Define the contributions of contact-dependent and -independent plant signals to formation of novel morphological changes at the A. tumefaciens polar membrane. Aim 2: Genetic basis for morphological changes at the A. tumefaciens polar membrane. Aim 3: Immuno-localization of VirB proteins Aim 4: Structural definition of the substrate translocation route. There were no major revisions to the aims, and the work focused on the above questions. Background: Agrobacterium presents a unique example of inter-kingdom gene transfer. The process involves cell to cell transfer of both protein and DNA substrates via a contact-dependent mechanism akin to bacterial conjugation. Transfer is mediated by a T4SS. Intensive study of the Agrobacterium T4SS has made it an archetypal model for the genetics and biochemistry. The channel is assembled from eleven protein components encoded on the B operon in the virulence region of the tumor-inducing plasmid, plus an additional coupling protein, VirD4. During the course of our project two structural studies were published presenting X-ray crystallography and three-dimensional reconstruction from electron microscopy of a core complex of the channel assembled in vitro from homologous proteins of E. coli, representing VirB7, VirB9, and VirB10. Another study was published claiming that the secretion channels in Agrobacterium appear on helical arrays around the membrane perimeter and along the entire length of the bacterium. Helical arrangements in bacterial membranes have since fallen from favor however, and that finding was partially retracted in a second publication. Overall, the localization of the T4SS within the bacterial membranes remains enigmatic in the literature, and we believe that our results from this project make a significant advance. Summary of achievements : We found that polar inflations and other membrane disturbances relate to the activation conditions rather than to virulence protein expression. Activation requires low pH and nutrient-poor medium. These stress conditions are also reflected in DNA condensation to varying degrees. Nonetheless, they must be considered in modeling the T4SS as they represent the relevant conditions for its expression and activity. We identified the T4SS core component VirB7 at native expression levels using state of the art super-resolution light microscopy. This marker of the secretion system was found almost exclusively at the cell poles, and typically one pole. Immuno-electron microscopy identified the protein at the inner membrane, rather than at bridges across the inner and outer membranes. This suggests a rare or transient assembly of the secretion-competent channel, or alternatively a two-step secretion involving an intermediate step in the periplasmic space. We followed the expression of the major secreted effector, VirE2. This is a single-stranded DNA binding protein that forms a capsid around the transferred oligonucleotide, adapting the bacterial conjugation to the eukaryotic host. We found that over-expressed VirE2 forms filamentous complexes in the bacterial cytoplasm that could be observed both by conventional fluorescence microscopy and by correlative electron cryo-tomography. Using a non-retentive mutant we observed secretion of VirE2 from bacterial poles. We labeled the secreted substrates in vivo in order detect their secretion and appearance in the plant cells. However the low transfer efficiency and significant background signal have so far hampered this approach.
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Andrawes, Bassem, Ernesto Perez Claros e Zige Zhang. Bond Characteristics and Experimental Behavior of Textured Epoxy-coated Rebars Used in Concrete Bridge Decks. Illinois Center for Transportation, gennaio 2022. http://dx.doi.org/10.36501/0197-9191/22-001.
Testo completoAbstract (sommario):
The deterioration of bridge decks is a problem typically associated with the corrosion of the reinforcing steel. This issue was partially controlled during the 1970s with the incorporation of the epoxy-coating protection system. However, research later demonstrated that the smooth surface resulting from the epoxy-coating application reduces most of the friction between the rebar and the surrounding concrete. Consequently, forces acting on the rib faces are reconfigured in such a way that the radial components increase, triggering the early development of cracks. To mitigate both the reduction of bonding and the formation of cracks, the Illinois Department of Transportation proposed a new type of coated bars: textured epoxy-coated (TEC) bars. Over the last few years, different projects have been executed to understand and improve the characteristics of TEC rebars. This report is a continuation of research performed at the University of Illinois Urbana-Champaign to evaluate the bond behavior of TEC bars. The experimental program starts by characterizing, qualitatively and quantitatively, the roughness of the TEC rebars. Next, their bond-slip interaction embedded in concrete is evaluated through pull-out tests. Finite element models of these tests are developed to validate the behavior observed as the textured reinforcement loses anchorage with concrete. Based on these results, the experimental program then aims to study the impact of the drying shrinkage, temperature change, and flexural demands on two large-scale bridge deck specimens reinforced, individually, with TEC and standard epoxy-coated bars. The results collected from both specimens using digital image correlation and strain gauges are compared to explore the differences exhibited by the traditional and the new type of reinforcement coatings in terms of stress distribution in bridge decks. Finally, given the specialized equipment and time-consuming procedure needed to calculate the roughness parameters of TEC bars, an empirical, weight-based approach is developed as a rapid method for assessing the rebars’ roughness on-site.
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Aly, Radi, e John I. Yoder. Development of resistant crop plants to parasitic weeds based on trans-specific gene silencing. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598146.bard.
Testo completoAbstract (sommario):
Broomrapes (Orobanche/Phelipanchespp.) are holo parasitic plants that subsist on the roots of a variety of agricultural crops and cause severe losses to the yield quality and quantity. Effective methods for controlling parasitic weeds are scarce, with only a few known cases of genetic resistance. In the current study, we proposed an improved strategy for the control of parasitic weeds based on trans-specific gene-silencing of three parasite genes at once. We used two strategies to express dsRNA containing selected sequences of three Phelipancheaegyptiacagenes PaACS, PaM6PR and PaPrx1 (pma): transient expression using Tobacco rattle virus (TRV:pma) as a virus-induced gene-silencing (VIGS) vector and stable expression in transgenic tomato Solanumlycopersicum(Mill.) plants harboring a hairpin construct (pBINPLUS35:pma). siRNA-mediated transgene-silencing (20–24 nt) was detected in the host plants. Our results demonstrate that the quantities of PaACSand PaM6PR transcripts from P. aegyptiacatubercles grown on transgenic tomato or on Tobacco rattle virus-infected Nicotianabenthamianaplants were significantly reduced. However, only partial reductions in the quantity of PaPrx1 transcripts were observed in the parasite tubercles grown on tomato and on N. benthamianaplants. Concomitant with the suppression of the target genes, there were significant decreases in the number and weight of the parasite tubercles that grew on the host plants, in both the transient and the stable experimental systems. The results of the work carried out using both strategies point to the movement of mobile exogenous siRNA from the host to the parasite, leading to the impaired expression of essential parasite target genes. In light of the importance of parasitic weeds to world agriculture and the difficulty of obtaining resistance by conventional methods, we assume that genetic resistance based on the silencing of key metabolic genes in the parasite is now feasible. BARD Report - Project4622 Page 2 of 60
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Friedman, Haya, Julia Vrebalov e James Giovannoni. Elucidating the ripening signaling pathway in banana for improved fruit quality, shelf-life and food security. United States Department of Agriculture, ottobre 2014. http://dx.doi.org/10.32747/2014.7594401.bard.
Testo completoAbstract (sommario):
Background : Banana being a monocot and having distinct peel and pulp tissues is unique among the fleshy fruits and hence can provide a more comprehensive understanding of fruit ripening. Our previous research which translated ripening discoveries from tomato, led to the identification of six banana fruit-associated MADS-box genes, and we confirmed the positive role of MaMADS1/2 in banana ripening. The overall goal was to further elucidate the banana ripening signaling pathway as mediated by MADS-boxtranscriptional regulators. Specific objectives were: 1) characterize transcriptional profiles and quality of MaMADS1/2 repressed fruit; 2) reveal the role of additional MaMADSgenes in ripening; 3) develop a model of fruit MaMADS-box mode of action; and 4) isolate new components of the banana ripening signaling pathway. Major conclusion: The functions of the banana MaMADS1-5 have been examined by complimenting the rinor the TAGL1-suppressed lines of tomato. Only MaMADS5 exhibited partial complementation of TAGL1-suppressed and rinlines, suggesting that while similar genes play corresponding roles in ripening, evolutionary divergence makes heterologous complementation studies challenging. Nevertheless, the partial complementation of tomato TAGL1-surpessed and rinlines with MaMADS5 suggests this gene is likely an important ripening regulator in banana, worthy of further study. RNA-seqtranscriptome analysis during ripening was performed on WT and MaMADS2-suppressed lines revealing additional candidate genes contributing to ripening control mechanisms. In summary, we discovered 39 MaMADS-box genes in addition to homologues of CNR, NOR and HB-1 expressed in banana fruits, and which were shown in tomato to play necessary roles in ripening. For most of these genes the expression in peel and pulp was similar. However, a number of key genes were differentially expressed between these tissues indicating that the regulatory components which are active in peel and pulp include both common and tissue-specific regulatory systems, a distinction as compared to the more uniform tomato fruit pericarp. Because plant hormones are well documented to affect fruit ripening, the expressions of genes within the auxin, gibberellin, abscisic acid, jasmonic acid, salicylic and ethylene signal transduction and synthesis pathways were targeted in our transcriptome analysis. Genes’ expression associated with these pathways generally declined during normal ripening in both peel and pulp, excluding cytokinin and ethylene, and this decline was delayed in MaMADS2-suppressed banana lines. Hence, we suggest that normal MaMADS2 activity promotes the observed downward expression within these non-ethylene pathways (especially in the pulp), thus enabling ripening progression. In contrast, the expressions of ACSand ACOof the ethylene biosynthesis pathway increase in peel and pulp during ripening and are delayed/inhibited in the transgenic bananas, explaining the reduced ethylene production of MaMADS2-suppressed lines. Inferred by the different genes’ expression in peel and pulp of the gibberellins, salicylic acid and cytokinins pathways, it is suggested that hormonal regulation in these tissues is diverse. These results provide important insights into possible avenues of ripening control in the diverse fruit tissues of banana which was not previously revealed in other ripening systems. As such, our transcriptome analysis of WT and ripening delayed banana mutants provides a starting point for further characterization of ripening. In this study we also developed novel evidence that the cytoskeleton may have a positive role in ripening as components of this pathway were down-regulated by MaMADS2 suppression. The mode of cytoskeleton involvement in fruit ripening remains unclear but presents a novel new frontier in ripening investigations. In summary, this project yielded functional understanding of the role and mode of action of MaMADS2 during ripening, pointing to both induction of ethylene and suppression of non-ethylene hormonal singling pathways. Furthermore, our data suggest important roles for cytoskeleton components and MaMADS5 in the overall banana ripening control network. Implications: The project revealed new molecular components/genes involved in banana ripening and refines our understanding of ripening responses in the peel and pulp tissues of this important species. This information is novel as compared to that derived from the more uniform carpel tissues of other highly studied ripening systems including tomato and grape. The work provides specific target genes for potential modification through genetic engineering or for exploration of useful genetic diversity in traditional breeding. The results from the project might point toward improved methods or new treatments to improve banana fruit storage and quality.
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Financial Infrastructure Report 2022. Banco de la República, giugno 2023. http://dx.doi.org/10.32468/rept-sist-pag.eng.2022.
Testo completoAbstract (sommario):
Banco de la República's monitoring of the local financial market infrastructure is an additional contribution to the country's financial stability. One of the products of that monitoring has been the Payment Systems Report, which is now known as the Financial Infrastructure Report. The change in name, as of this edition, is intended to reflect in a broader way the issues that are addressed in the report. The 2022 edition includes several changes that are the result of a comparative study of financial infrastructure reports prepared by other central banks. These changes seek to make the report more fluid and easier to read, including main points and selected key figures for the different interest groups to which it is addressed. The report shows the financial infrastructure continued to render its services without interruption, with general evidence of good performance in 2021. Additionally, the resilience of the Central Counterparty Risk of Colombia (CRCC) and the Large-value Payments System (CUD) to extreme events was validated, based on stress tests conducted according to international standards (focused on liquidity and credit risk). As for retail payments, transactional information indicates the use of electronic instruments increased in terms of value during 2021 compared to 2020 (credit and debit cards, checks and electronic funds transfers). The use of debit and credit cards in payments rose to levels similar to those reached in the pre-pandemic year. Meanwhile, electronic funds transfers continued to grow. Although the results of the BR 2022 survey show cash continues to be the instrument most used by the public for regular payments (like the situation in other countries), the perception of its use decreased significantly to 75 % (87 % in 2019). Also, in commerce, cash was the preferred instrument for customers. However, in this measurement, several retail channels such as hairdressers, drugstores and restaurants joined the group that has traditionally received electronic payments for a value greater than 10% of their sales (hypermarkets and gas stations). Likewise, for nearly 50% of the population, cash payments are lower than before the pandemic. This is consistent with the transactional increase in electronic payment instruments that was observed in 2021. Banco de la República continues to monitor the technological developments that have expanded and modernized the supply in the international and local payments market, as these are issues of interest to the industry that provides clearing and settlement services. This report outlines the Pix case for instant payments in Brazil, the projects that are underway regarding the possible issue of digital currency by central banks (CBDC) for cross-border payments, as well as an approach to the Fintech ecosystem in Colombia, with an emphasis on companies that provide payment services. Leonardo Villar Governor Main points: 2022 The local financial infrastructure was safe and efficient throughout the year. The services of the financial infrastructure were proved on a continuous basis, showing good performance overall. Less momentum in the large-value payment system CUD activity declined versus the previous year because of fewer government deposits with BanRep. This was offset partially by growth in repos to increase money supply and in retail-value payments (electronic funds transfers, checks and cards). Increased momentum in financial market infrastructures. Larger amounts were cleared and settled through the Central Securities Depository (DCV) due to an increase in the market for sovereign debt. Operations managed by the Central Counterparty Risk of Colombia (CRCC) increased due to inclusion of the foreign exchange segment and the positive evolution in non-delivery forward peso/dollar contracts. Added confidence in the peso/dollar spot foreign exchange market due to CRCC interposition. Number and value of trades grew, mainly due to the adjustment of therisk management model for the FX segment and the increase in the limiton net selling positions in dollars. Stress testing with international standards to validate CRCC and CUD resilience Stress tests conducted independently by the SFC, BanRep and the CRCC, like those done in England and the United States, concluded that the CRCC's risk management model allows it to withstand extreme market events and simultaneous defaults by its main members. Based on the experience of other central banks, BanRep strengthened its intraday liquidity risk stress exercises in the CUD by incorporating temporary payment delays. It calculated that a two-hour delay by a key participant increases the system's liquidity needs by 0.5%. Electronic payments increased during 2021 According to transactional information, all electronic payment instruments increased in value versus 2020 (electronic funds transfers, checks and debit and credit cards). Electronic funds transfers continued to grow (80% from legal entities), with the participation of closed schemes driven particularly by the use of mobile wallets (35% of the number of intra-transfer transactions). The use of debit and credit cards for payments climbed to levels similar to those witnessed in the pre-pandemic year. Cash continues to be the instrument most used by the public for regular payments. The results of the BanRep survey in 2022 show that the perception of the use of cash declined significantly to 75% (87% in 2019), and about 50% of the population perceive their cash payments as being lower than those they made before the pandemic. Electronic funds transfers were second most used instrument, having increased to 15% (3% in 2019). Also, in commerce, cash was the preferred instrument of payment for its customers; however, several commerce channels received more than 10% of the value of their sales in electronic payments (hypermarkets 35%, gas stations 25%, hairdressers 15%, drugstores 14% and restaurants 12%). Continuous technological developments have broadened, and modernized services offered in the payments market. Pix (instant payments in Brazil). The high level of adoption of instant transfers in Brazil motivated a review of its strengths; namely, the possibility of different use cases between individuals, businesses, and government; high participation by financial and payment institutions; free of charge for individuals and the possibility of charging legal entities, and simple user experience. Digital currencies in central banking. Several groups of countries have joined forces to conduct pilot projects with wholesale CBDCs for cross-border payments. Flows generated by international trade, foreign investment and remittances between individuals can be processed more efficiently, transparently, and securely by reducing their cost and increasing their speed. Due to the constant progress being made on this issue, BanRep will continue to monitor all CBDC-related matters. The fintech ecosystem for payments in Colombia. A high percentage of existing FinTech companies in the country are dedicated to offering digital payment services: wallets, payment gateways, mobile devices (point-of-sale terminals) and acquisition. These have driven innovation in payment services.