Relevant bibliographies by topics / Constrained exploration

Academic literature on the topic 'Constrained exploration'

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Published: 1 June 2024

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Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Journal articles on the topic "Constrained exploration":

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Pankayaraj, Pathmanathan, and Pradeep Varakantham. "Constrained Reinforcement Learning in Hard Exploration Problems." Proceedings of the AAAI Conference on Artificial Intelligence 37, no. 12 (June 26, 2023): 15055–63. http://dx.doi.org/10.1609/aaai.v37i12.26757.

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One approach to guaranteeing safety in Reinforcement Learning is through cost constraints that are dependent on the policy. Recent works in constrained RL have developed methods that ensure constraints are enforced even at learning time while maximizing the overall value of the policy. Unfortunately, as demonstrated in our experimental results, such approaches do not perform well on complex multi-level tasks, with longer episode lengths or sparse rewards. To that end, we propose a scalable hierarchical approach for constrained RL problems that employs backward cost value functions in the context of task hierarchy and a novel intrinsic reward function in lower levels of the hierarchy to enable cost constraint enforcement. One of our key contributions is in proving that backward value functions are theoretically viable even when there are multiple levels of decision making. We also show that our new approach, referred to as Hierarchically Limited consTraint Enforcement (HiLiTE) significantly improves on state of the art Constrained RL approaches for many benchmark problems from literature. We further demonstrate that this performance (on value and constraint enforcement) clearly outperforms existing best approaches for constrained RL and hierarchical RL.
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Mellado, Nicolas, David Vanderhaeghe, Charlotte Hoarau, Sidonie Christophe, Mathieu Brédif, and Loic Barthe. "Constrained palette-space exploration." ACM Transactions on Graphics 36, no. 4 (July 20, 2017): 1–14. http://dx.doi.org/10.1145/3072959.3073650.

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Duncan, Christian A., Stephen G. Kobourov, and V. S. Anil Kumar. "Optimal constrained graph exploration." ACM Transactions on Algorithms 2, no. 3 (July 2006): 380–402. http://dx.doi.org/10.1145/1159892.1159897.

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Yang, Qisong, and Matthijs T. J. Spaan. "CEM: Constrained Entropy Maximization for Task-Agnostic Safe Exploration." Proceedings of the AAAI Conference on Artificial Intelligence 37, no. 9 (June 26, 2023): 10798–806. http://dx.doi.org/10.1609/aaai.v37i9.26281.

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In the absence of assigned tasks, a learning agent typically seeks to explore its environment efficiently. However, the pursuit of exploration will bring more safety risks. An under-explored aspect of reinforcement learning is how to achieve safe efficient exploration when the task is unknown. In this paper, we propose a practical Constrained Entropy Maximization (CEM) algorithm to solve task-agnostic safe exploration problems, which naturally require a finite horizon and undiscounted constraints on safety costs. The CEM algorithm aims to learn a policy that maximizes state entropy under the premise of safety. To avoid approximating the state density in complex domains, CEM leverages a k-nearest neighbor entropy estimator to evaluate the efficiency of exploration. In terms of safety, CEM minimizes the safety costs, and adaptively trades off safety and exploration based on the current constraint satisfaction. The empirical analysis shows that CEM enables the acquisition of a safe exploration policy in complex environments, resulting in improved performance in both safety and sample efficiency for target tasks.
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Ivanov, Alexander, and Mark Campbell. "Uncertainty Constrained Robotic Exploration: An Integrated Exploration Planner." IEEE Transactions on Control Systems Technology 27, no. 1 (January 2019): 146–60. http://dx.doi.org/10.1109/tcst.2017.2759729.

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Ahuir, J., A. S. Brun, and A. Strugarek. "From stellar coronae to gyrochronology: A theoretical and observational exploration." Astronomy & Astrophysics 635 (March 2020): A170. http://dx.doi.org/10.1051/0004-6361/201936974.

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Context. Stellar spin down is the result of a complex process involving rotation, dynamo, wind, and magnetism. Multiwavelength surveys of solar-like stars have revealed the likely existence of relationships between their rotation, X-ray luminosity, mass losses, and magnetism. They impose strong constraints on the corona and wind of cool stars. Aims. We aim to provide power-law prescriptions of the mass loss of stars, of their magnetic field, and of their base coronal density and temperature that are compatible with their observationally-constrained spin down. Methods. We link the magnetic field and the mass-loss rate from a wind torque formulation, which is in agreement with the distribution of stellar rotation periods in open clusters and the Skumanich law. Given a wind model and an expression of the X-ray luminosity from radiative losses, we constrained the coronal properties by assuming different physical scenarios linking closed loops to coronal holes. Results. We find that the magnetic field and the mass loss are involved in a one-to-one correspondence that is constrained from spin down considerations. We show that a magnetic field, depending on both the Rossby number and the stellar mass, is required to keep a consistent spin down model. The estimates of the magnetic field and the mass-loss rate obtained from our formalism are consistent with statistical studies as well as individual observations and they give new leads to constrain the magnetic field-rotation relation. The set of scaling-laws we derived can be broadly applied to cool stars from the pre-main sequence to the end of the main sequence (MS), and they allow for stellar wind modeling that is consistent with all of the observational constraints available to date.
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Deng, Bailin, Sofien Bouaziz, Mario Deuss, Alexandre Kaspar, Yuliy Schwartzburg, and Mark Pauly. "Interactive design exploration for constrained meshes." Computer-Aided Design 61 (April 2015): 13–23. http://dx.doi.org/10.1016/j.cad.2014.01.004.

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Yang, Yong-Liang, Yi-Jun Yang, Helmut Pottmann, and Niloy J. Mitra. "Shape space exploration of constrained meshes." ACM Transactions on Graphics 30, no. 6 (December 2011): 1–12. http://dx.doi.org/10.1145/2070781.2024158.

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Angmalisang, Helen Yuliana, Syaiful Anam, and Sobri Abusini. "Leaders and followers algorithm for constrained non-linear optimization." Indonesian Journal of Electrical Engineering and Computer Science 13, no. 1 (January 1, 2019): 162. http://dx.doi.org/10.11591/ijeecs.v13.i1.pp162-169.

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<p>Leaders and Followers algorithm was a novel metaheuristics proposed by Yasser Gonzalez-Fernandez and Stephen Chen. In solving unconstrained optimization, it performed better exploration than other well-known metaheuristics, e.g. Genetic Algorithm, Particle Swarm Optimization and Differential Evolution. Therefore, it performed well in multi-modal problems. In this paper, Leaders and Followers was modified for constrained non-linear optimization. Several well-known benchmark problems for constrained optimization were used to evaluate the proposed algorithm. The result of the evaluation showed that the proposed algorithm consistently and successfully found the optimal solution of low dimensional constrained optimization problems and high dimensional optimization with high number of linear inequality constraint only. Moreover, the proposed algorithm had difficulty in solving high dimensional optimization problem with non-linear constraints and any problem which has more than one equality constraint. In the comparison with other metaheuristics, Leaders and Followers had better performance in overall benchmark problems.</p>
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Francis, Gilad, Lionel Ott, Roman Marchant, and Fabio Ramos. "Occupancy map building through Bayesian exploration." International Journal of Robotics Research 38, no. 7 (May 6, 2019): 769–92. http://dx.doi.org/10.1177/0278364919846549.

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We propose a novel holistic approach to safe autonomous exploration and map building based on constrained Bayesian optimization. This method finds optimal continuous paths instead of discrete sensing locations that inherently satisfy motion and safety constraints. Evaluating both the objective and constraints functions requires forward simulation of expected observations. As such, evaluations are costly, and therefore the Bayesian optimizer proposes only paths that are likely to yield optimal results and satisfy the constraints with high confidence. By balancing the reward and risk associated with each path, the optimizer minimizes the number of expensive function evaluations. We demonstrate the effectiveness of our approach in a series of experiments both in simulation and with a real ground robot and provide comparisons with other exploration techniques. The experimental results show that our method provides robust and consistent performance in all tests and performs better than or as good as the state of the art.
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Journal articles Dissertations / Theses Books

Dissertations / Theses on the topic "Constrained exploration":

1

Garcelon, Evrard. "Constrained Exploration in Reinforcement Learning." Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAG007.

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Une application majeure de l'apprentissage machine automatisée est la personnalisation des différents contenus recommandé à différents utilisateurs. Généralement, les algorithmes étant à la base de ces systèmes sont dit supervisé. C'est-à-dire que les données utilisées lors de la phase d'apprentissage sont supposées provenir de la même distribution. Cependant, ces données sont générées par des interactions entre un utilisateur et ces mêmes algorithmes. Ainsi, les recommandations pour un utilisateur à un instant t peuvent modifier l'ensemble des recommandations pertinentes à un instant ultérieur. Il est donc nécessaire de prendre en compte ces interactions afin de produire un service de la meilleure qualité possible. Ce type d'interaction est réminiscente du problème d'apprentissage en ligne. Parmi les algorithmes dit en ligne, les algorithmes de bandits et d'apprentissage par Renforcement (AR) semblent être les mieux positionnés afin de remplacer les méthodes d'apprentissage supervisé pour des applications nécessitant un certain degré de personnalisation. Le déploiement en production d'algorithmes d'apprentissage par Renforcement présente un certain nombre de difficultés tel que garantir un certain niveau de performance lors des phases d'exploration ou encore comment garantir la confidentialité des données collectées par ces algorithmes. Dans cette thèse nous considérons différentes contraintes freinant l’utilisation d’algorithmes d’apprentissage par renforcement, en fournissant des résultats à la fois empirique et théorique sur la vitesse d’apprentissage en présence de différentes contraintes
A major application of machine learning is to provide personnalized content to different users. In general, the algorithms powering those recommandation are supervised learning algorithm. That is to say the data used to train those algorithms are assumed to be sampled from the same distribution. However, the data are generated through interactions between the users and the recommendation algorithms. Thus, recommendations for a user a time t can have an impact on the set of pertinent recommandation at a later time. Therefore, it is necessary to take those interactions into account. This setting is reminiscent of the online learning setting. Among online learning algorithms, Reinforcement Learning algorithms (RL) looks the most promising to replace supervised learning algorithms for applications requiring a certain degree of personnalization. The deployement in production of RL algorithms presents some challenges such as being able to guarantee a certain level of performance during exploration phases or how to guarantee privacy of the data collected by RL algorithms. In this thesis, we consider different constraints limiting the use of RL algorithms and provides both empirical and theoretical results on the impact of those constraints on the learning process
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Carvalho, Filho José Gilmar Nunes de. "Multi-robot exploration with constrained communication." reponame:Repositório Institucional da UFSC, 2016. https://repositorio.ufsc.br/xmlui/handle/123456789/171998.

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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2016.
Made available in DSpace on 2016-12-27T03:11:05Z (GMT). No. of bitstreams: 1 342277.pdf: 5444057 bytes, checksum: 36965f3be2f7f870b8ed9ef5eee8e702 (MD5) Previous issue date: 2016
Abstract : Over the last two decades, several methods for exploration with Multi-Robot Systems (MRS) have been proposed, most of them based on the allocation of frontiers (exploration targets) and typically applying local optimization policies. However, communication issues have usually been neglected. This thesis investigates multi-robot exploration by considering that robots have limited communication radius. Two methods, one based on a flat network architecture (DSM) and another based on a hierarchical architecture (HSM), were proposed to share map information. While DSM considers a propagation scheme to share information and synchronize the map of robots, HSM organizes robots in a hierarchical architecture where some robots act as leaders (clusterheads) and are responsible for synchronizing the maps of the robots in the network. Formal proof that both methods guarantee the synchronization of the map of all robots in a network is presented. In addition, experiments were conducted by considering systems with different number of robots, network topologies and different map's sizes. The results show that both methods are able to synchronize the map of the robots when they can lose communication links, but HKM usually presents smaller convergence time, number of exchanged messages and amount of transmitted data. We also propose Hierarchical K-Means (HKME), a method for multi-robot coordination in exploration tasks that handles communication problems, such as link losses. To handle communication among robots, HKME arranges them into clusters and elects leaders for each. Clusters evolve dynamically as robots lose or establish communication with their peers. HKME uses HSM to guarantee that the map of the robots are synchronized and also uses the hierarchical organization of the robots to coordinate them in order to minimize the variance of the time at which they reach all regions of the workspace, while balancing their workload and decreasing the exploration time. Experiments were conducted by considering different types of workspace and communication radius. The results show that HKME behaves like a centralized algorithm when communication is granted, while being able to withstand severe degradation in communication radius.

Ao longo das últimas décadas, vários métodos de exploração com os Sistemas Multi-robôs (SMR) têm sido propostos, a maioria deles com base na alocação de fronteiras (alvos de exploração) e normalmente aplicando políticas de otimização locais. No entanto, os problemas de comunicação têm geralmente sido negligenciados. Esta tese investiga a exploração multi-robô, considerando que os robôs têm raio de comunicação limitado. Dois métodos, um baseado em uma arquitetura de rede plana (DSM) e outro baseado em uma arquitetura hierárquica (HSM), foram propostos para compartilhar informações de mapa. Enquanto o DSM considera um esquema de propagação para compartilhar informações e sincronizar o mapa dos robôs, o HSM organiza robôs em uma arquitetura hierárquica, onde alguns robôs atuam como líderes (clusterheads) e são responsáveis por sincronizar os mapas dos robôs na rede. A prova formal de que ambos os métodos garantem a sincronização do mapa de todos os robôs na rede é apresentada. Além disso, experimentos foram conduzidos considerando sistemas com diferentes números de robôs, topologias de rede e tamanhos de mapa. Os resultados mostram que ambos os métodos são capazes de sincronizar o mapa dos robôs quando eles podem perder links de comunicação, mas o HKM geralmente apresenta menor tempo de convergência, o número de mensagens trocadas e a quantidade de dados transmitidos. Propomos também Hierarchical K-Means (HKME), um método de coordenação multi-robô em tarefas de exploração que lida com problemas de comunicação, tais como perdas de links. Para lidar com a comunicação entre robôs, o HKME os organiza em clusters e elege os líderes de cada um. Clusters evoluem dinamicamente a medida que os robôs perdem ou estabelecem links de comunicação. O HKME usa o HSM para garantir que o mapa dos robôs se mantenham sincronizados e também usa a organização hierárquica dos robôs para coordená-los, a fim de minimizar a variância do momento em que eles atinjem todas as regiões do espaço de trabalho, ao mesmo tempo que equilibra a carga de trabalho e diminui o tempo de exploração. Experimentos foram realizadas considerando diferentes tipos de espaço de trabalho e raios de comunicação. Os resultados mostram que o HKME comporta-se como um algoritmo centralizada quando a comunicação é garantida, sendo capaz de lidar com uma degradação severa no raio de comunicação.
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Duong, Khanh-Chuong. "Constrained clustering by constraint programming." Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2049/document.

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La classification non supervisée, souvent appelée par le terme anglais de clustering, est une tâche importante en Fouille de Données. Depuis une dizaine d'années, la classification non supervisée a été étendue pour intégrer des contraintes utilisateur permettant de modéliser des connaissances préalables dans le processus de clustering. Différents types de contraintes utilisateur peuvent être considérés, des contraintes pouvant porter soit sur les clusters, soit sur les instances. Dans cette thèse, nous étudions le cadre de la Programmation par Contraintes (PPC) pour modéliser les tâches de clustering sous contraintes utilisateur. Utiliser la PPC a deux avantages principaux : la déclarativité, qui permet d'intégrer aisément des contraintes utilisateur et la capacité de trouver une solution optimale qui satisfait toutes les contraintes (s'il en existe). Nous proposons deux modèles basés sur la PPC pour le clustering sous contraintes utilisateur. Les modèles sont généraux et flexibles, ils permettent d'intégrer des contraintes d'instances must-link et cannot-link et différents types de contraintes sur les clusters. Ils offrent également à l'utilisateur le choix entre différents critères d'optimisation. Afin d'améliorer l'efficacité, divers aspects sont étudiés. Les expérimentations sur des bases de données classiques et variées montrent qu'ils sont compétitifs par rapport aux approches exactes existantes. Nous montrons que nos modèles peuvent être intégrés dans une procédure plus générale et nous l'illustrons par la recherche de la frontière de Pareto dans un problème de clustering bi-critère sous contraintes utilisateur
Cluster analysis is an important task in Data Mining with hundreds of different approaches in the literature. Since the last decade, the cluster analysis has been extended to constrained clustering, also called semi-supervised clustering, so as to integrate previous knowledge on data to clustering algorithms. In this dissertation, we explore Constraint Programming (CP) for solving the task of constrained clustering. The main principles in CP are: (1) users specify declaratively the problem in a Constraint Satisfaction Problem; (2) solvers search for solutions by constraint propagation and search. Relying on CP has two main advantages: the declarativity, which enables to easily add new constraints and the ability to find an optimal solution satisfying all the constraints (when there exists one). We propose two models based on CP to address constrained clustering tasks. The models are flexible and general and supports instance-level constraints and different cluster-level constraints. It also allows the users to choose among different optimization criteria. In order to improve the efficiency, different aspects have been studied in the dissertation. Experiments on various classical datasets show that our models are competitive with other exact approaches. We show that our models can easily be embedded in a more general process and we illustrate this on the problem of finding the Pareto front of a bi-criterion optimization process
4

Kettler, Daniel Terrance. "Mechanical design for the tactile exploration of constrained internal geometries." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50272.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
MIT Institute Archives copy: with CD-ROM; divisional library copy with no CD-ROM.
Includes bibliographical references (p. 93-98).
Rising world oil prices and advanced oil recovery techniques have made it economically attractive to rehabilitate abandoned oil wells. This requires guiding tools through well junctions where divergent branches leave the main wellbore. The unknown locations and shapes of these junctions must be determined. Harsh down-well conditions prevent the use of ranged sensors. However, robotic tactile exploration using a manipulator is well suited to this problem. This tactile characterization must be done quickly because of the high costs of working on oil wells. Consequently, intelligent tactile exploration algorithms that can characterize a shape using sparse data sets must be developed. This thesis explores the design and system architecture of robotic manipulators for down-well tactile exploration. A design approach minimizing sensing is adopted to produce a system that is mechanically robust and suited to the harsh down-well environment. A feasibility study on down-well tactile exploration manipulators is conducted. This study focuses on the mature robotic technology of link and joint manipulators with zero or low kinematic redundancy. This study produces a field system architecture that specifies a unified combination of control, sensing, kinematic solutions for down-well applications. An experimental system is built to demonstrate the proposed field system architecture and test control and intelligent tactile exploration algorithms. Experimental results to date have indicated acceptability of the proposed field system architecture and have demonstrated the ability to characterize geometry with sparse tactile data.
(cont.) Serpentine manipulators implemented using digital mechatronic actuation are also considered. Digital mechatronic devices use actuators with discrete output states and the potential to be mechanically robust and inexpensive. The design of digital mechatronic devices is challenging. Design parameter optimization methods are developed and applied to a design case study of a manipulator in a constrained workspace. This research demonstrates that down-well tactile exploration with a manipulator is feasible. Experimental results show that the proposed field system architecture, a 4 degree-of-freedom anthropomorphic manipulator, can obtain accurate tactile data without using any sensor feedback besides manipulator joint angles.
by Daniel Terrance Kettler.
S.M.
5

Chung, Jen Jen. "Learning to soar: exploration strategies in reinforcement learning for resource-constrained missions." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11733.

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An unpowered aerial glider learning to soar in a wind field presents a new manifestation of the exploration-exploitation trade-off. This thesis proposes a directed, adaptive and nonmyopic exploration strategy in a temporal difference reinforcement learning framework for tackling the resource-constrained exploration-exploitation task of this autonomous soaring problem. The complete learning algorithm is developed in a SARSA() framework, which uses a Gaussian process with a squared exponential covariance function to approximate the value function. The three key contributions of this thesis form the proposed exploration-exploitation strategy. Firstly, a new information measure is derived from the change in the variance volume surrounding the Gaussian process estimate. This measure of information gain is used to define the exploration reward of an observation. Secondly, a nonmyopic information value is presented that captures both the immediate exploration reward due to taking an action as well as future exploration opportunities that result. Finally, this information value is combined with the state-action value of SARSA() through a dynamic weighting factor to produce an exploration-exploitation management scheme for resource-constrained learning systems. The proposed learning strategy encourages either exploratory or exploitative behaviour depending on the requirements of the learning task and the available resources. The performance of the learning algorithms presented in this thesis is compared against other SARSA() methods. Results show that actively directing exploration to regions of the state-action space with high uncertainty improves the rate of learning, while dynamic management of the exploration-exploitation behaviour according to the available resources produces prudent learning behaviour in resource-constrained systems.
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Sun, Hua. "Throughput constrained and area optimized dataflow synthesis for FPGAS." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2276.pdf.

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Bhattacharjee, Protim [Verfasser], Veniamin [Akademischer Betreuer] Morgenshtern, and Martin [Gutachter] Burger. "Compressed Sensing based Image Acquisition Methodologies for Constrained Autonomous Exploration Systems with Single Pixel Cameras / Protim Bhattacharjee ; Gutachter: Martin Burger ; Betreuer: Veniamin Morgenshtern." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/123348429X/34.

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Williams, Nicholas Cory. "Geologically-constrained UBC–GIF gravity and magnetic inversions with examples from the Agnew-Wiluna greenstone belt, Western Australia." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2744.

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Geologically-constrained inversion of geophysical data is a powerful method for predicting geology beneath cover. The process seeks 3D physical property models that are consistent with the geology and explain measured geophysical responses. The recovered models can guide mineral explorers to prospective host rocks, structures, alteration and mineralisation. This thesis provides a comprehensive analysis of how the University of British Columbia Geophysical Inversion Facility (UBC–GIF) gravity and magnetic inversions can be applied to subsurface mapping and exploration by demonstrating the necessary approach, data types, and typical results. The non-uniqueness of inversion demands that geological information be included. Commonly available geological data, including structural and physical property measurements, mapping, drilling, and 3D interpretations, can be translated into appropriate inversion constraints using tools developed herein. Surface information provides the greatest improvement in the reliability of recovered models; drilling information enhances resolution at depth. The process used to prepare inversions is as important as the geological constraints themselves. Use of a systematic workflow, as developed in this study, minimises any introduced ambiguity. Key steps include defining the problem, preparing the data, setting inversion parameters and developing geological constraints. Once reliable physical property models are recovered they must be interpreted in a geological context. Where alteration and mineralisation occupy significant volumes, the mineralogy associated with the physical properties can be identified; otherwise a lithological classification of the properties can be applied. This approach is used to develop predictive 3D lithological maps from geologically-constrained gravity and magnetic inversions at several scales in the Agnew-Wiluna greenstone belt in Australia’s Yilgarn Craton. These maps indicate a spatial correlation between thick mafic-ultramafic rock packages and gold deposit locations, suggesting a shared structural control. The maps also identify structural geometries and relationships consistent with the published regional tectonic framework. Geophysical inversion provides a framework into which geological and geophysical data sets can be integrated to produce a holistic prediction of the subsurface. The best possible result is one that cannot be dismissed as inconsistent with some piece of geological knowledge. Such a model can only be recovered by including all available geological knowledge using a consistent workflow process.
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Clifford, Gayle. ""Am iz kwiin" (I'm his queen) : an exploration of mothers' disclosure of maternal HIV to their children in Kingston, Jamaica : using feminist Interpretative Phenomenological Analysis (IPA) in a resource-constrained context." Thesis, City, University of London, 2018. http://openaccess.city.ac.uk/21213/.

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Introduction: World Health Organisation (WHO) policy presents parental HIV disclosure to children as beneficial and encourages parents to disclose. Most research on disclosure has been conducted in high income countries and tends to represent women’s choices in terms of a disclosure/non-disclosure binary which, I argue, is premised on rationalist theory models of decision making and disclosure which fail to contextualise women’s experiences, particularly those women who live in the Global South. This research study aimed to address gaps in existing research by exploring the maternal disclosure experiences of HIV positive Jamaican mothers to their seronegative children and offers a critique of existing WHO policy. Methods: I carried out in-depth interviews with 15 HIV positive Jamaican women with at least one seronegative child aged over 10 years, associated with one clinic and one NGO in Kingston, Jamaica. I adopted a feminist approach to Interpretative Phenomenological Analysis (IPA) and applied Hochschild’s concept of emotion work to make sense of women’s experiences. In attending to the structural factors shaping health actions, a feminist approach highlights the relationship between Jamaican contextual factors of poverty, violence and complex familial formations and women’s disclosure decisions. Conceptual resources drew on feminist critiques of dominant discourses of motherhood, including governmentality and responsibilisation, which, I argue, underpin policy imperatives on disclosure to children. Results: Mothers’ experiences of maternal disclosure to children occurred on a spectrum, rather than a disclosure/nondisclosure binary, and included: full disclosure, partial disclosure, nondisclosure, denial of HIV, differential disclosure (telling only some of their children) and disclosure by others. Experiences of disclosure were affected by financial risks and practical issues as well as consideration of children’s long-term physical and mental health, education prospects and the impact on other family relationships. Mothering at a distance (mothers living apart from their child/ren) and the fear or reality of ‘downfallment’ (a child being HIV positive) further complicated disclosure experiences. The women described strategies which challenged negative characterisations of HIV positive women in order to present themselves as capable mothers and manage their own and their children’s emotions. Conclusion: Disclosure of maternal HIV to children is a complex issue, carrying risks as well as benefits, which are particularly heightened in low income contexts. When women disclose this could be seen as a form of governmentality and when they don’t disclose their mothering is called into question within policy discourses predicated on evidence from the Anglo North. The over simplistic disclosure /non-disclosure binary fails to consider the emotion work women engage in to manage their illness and their mothering identity in the context of their relationships with their children. This research adds to the HIV disclosure literature from low and middle income countries and extends maternal HIV disclosure research through the use of a novel approach, feminist IPA, to understand women’s experiences. The research findings point to the need for a more nuanced policy on disclosure in low and middle income countries.
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Craparo, Emily M. (Emily Marie) 1980. "Cooperative exploration under communication constraints." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46558.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.
Includes bibliographical references (leaves 131-137).
The cooperative exploration problem necessarily involves communication among agents, while the spatial separation inherent in this task places fundamental limits on the amount of data that can be transmitted. However, the impact of limited communication on the exploration process has not been fully characterized. Existing exploration algorithms do not realistically model the tradeoff between expansion, which allows more rapid exploration of the area of interest, and maintenance of close relative proximity among agents, which facilitates communication. This thesis develops new algorithms applicable to the problem of cooperative exploration under communication constraints. The exploration problem is decomposed into two parts. In the first part, cooperative exploration is considered in the context of a hierarchical communication framework known as a mobile backbone network. In such a network, mobile backbone nodes, which have good mobility and communication capabilities, provide communication support for regular nodes, which are constrained in movement and communication capabilities but which can sense the environment. New exact and approximation algorithms are developed for throughput optimization in networks composed of stationary regular nodes, and new extensions are formulated to take advantage of regular node mobility. These algorithms are then applied to a cooperative coverage problem. In the second part of this work, techniques are developed for utilizing a given level of throughput in the context of cooperative estimation. The mathematical properties of the information form of the Kalman filter are leveraged in the development of two algorithms for selecting highly informative portions of the information matrix for transmission. One algorithm, a fully polynomial time approximation scheme, provides provably good results in computationally tractable time for problem instances of a particular structure. The other, a heuristic method applicable to instances of arbitrary matrix structure, performs very well in simulation for randomly-generated problems of realistic dimension.
by Emily M. Craparo.
Ph.D.
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Books on the topic "Constrained exploration":

1

National Research Council (U.S.). Committee to Review NASA's Exploration Technology Development Program. A constrained space exploration technology program: A review of NASA's exploration technology development program. Washington, D.C: National Academies Press, 2008.

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National Research Council (U.S.). Committee to Review NASA's Exploration Technology Development Program. A constrained space exploration technology program: A review of NASA's exploration technology development program. Washington, D.C: National Academies Press, 2008.

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National Research Council (U.S.). Committee to Review NASA's Exploration Technology Development Program. A constrained space exploration technology program: A review of NASA's exploration technology development program. Washington, D.C: National Academies Press, 2008.

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Meh, Césaire Assah. Entrepreneurial risk, credit constraints, and the corporate income tax: A quantitative exploration. Ottawa: Bank of Canada, 2002.

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Office, World Bank Indonesia, ed. Opportunities and constraints for civil service reform in Indonesia: Exploration of a new approach and methodology. Jakarta: World Bank Office Jakarta, 2006.

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Timmer, Adwin H. From design space exploration to code generation: A constraint satisfaction approach for the architectural synthesis of digital VLSI circuits : proefschrift / door Adwin H. Timmer. [S.l: s.n.,], 1996.

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A Constrained Space Exploration Technology Program. Washington, D.C.: National Academies Press, 2008. http://dx.doi.org/10.17226/12471.

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Aeronautics and Space Engineering Board, National Research Council, Division on Engineering and Physical Sciences, and Committee to Review NASA's Exploration Technology Development Program. Constrained Space Exploration Technology Program: A Review of NASA's Exploration Technology Development Program. National Academies Press, 2008.

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Aeronautics and Space Engineering Board, National Research Council, Division on Engineering and Physical Sciences, and Committee to Review NASA's Exploration Technology Development Program. Constrained Space Exploration Technology Program: A Review of NASA's Exploration Technology Development Program. National Academies Press, 2009.

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Aeronautics and Space Engineering Board, National Research Council, Division on Engineering and Physical Sciences, and Committee to Review NASA's Exploration Technology Development Program. Constrained Space Exploration Technology Program: A Review of NASA's Exploration Technology Development Program. National Academies Press, 2008.

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Book chapters on the topic "Constrained exploration":

1

Zhao, Xin, Cheng-Cheng Tang, Yong-Liang Yang, Helmut Pottmann, and Niloy J. Mitra. "Intuitive Design Exploration of Constrained Meshes." In Advances in Architectural Geometry 2012, 305–18. Vienna: Springer Vienna, 2013. http://dx.doi.org/10.1007/978-3-7091-1251-9_25.

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Das, Shantanu, Dariusz Dereniowski, and Christina Karousatou. "Collaborative Exploration by Energy-Constrained Mobile Robots." In Structural Information and Communication Complexity, 357–69. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-25258-2_25.

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Wang, Hui, Tie Cai, Yinfeng Wang, Geng Yang, and Junwei Liang. "Manifold Learning Algorithm Based on Constrained Particle Swarm Multi-objective Optimization." In Exploration of Novel Intelligent Optimization Algorithms, 71–80. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-4109-2_8.

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Venugopalan, Manju, and Deepa Gupta. "Sentiment Classification for Hindi Tweets in a Constrained Environment Augmented Using Tweet Specific Features." In Mining Intelligence and Knowledge Exploration, 664–70. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-26832-3_63.

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Saccani, Danilo. "Model Predictive Control for Constrained Navigation of Autonomous Vehicles." In Special Topics in Information Technology, 103–13. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-51500-2_9.

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AbstractAs autonomous vehicles become increasingly prevalent in our daily lives, new control challenges arise to ensure their safety and the safety of their surroundings. This work addresses these challenges by developing a suitable regulator that strikes a balance between different objectives. The first one is ‘safety’, which involves satisfying constraints and consistently avoiding obstacles. The second objective is ‘exploitation’, which aims to optimize the utilization of existing knowledge about the environment, reducing the overly cautious behaviour of guaranteed collision-free approaches. The third objective is ‘exploration’, which pertains to the ability to discover potential unknown areas while avoiding getting stuck in blocked regions. The design of motion planning algorithms for such systems requires carefully managing the trade-off between these requirements. Among the various approaches to dynamic path planning, discrete optimization methods such as Model Predictive Control (MPC) have gained significant attention. MPC excels in handling state and input constraints to ensure safety while minimizing a cost function defined by the user, enabling both exploitation and exploration aspects. By developing a suitable regulator and leveraging MPC approaches, this work aims to address the complex control challenges faced by autonomous vehicles and other safety-critical applications, ensuring a balance between safety, exploitation, and exploration.
6

Scrbak, Marko, Joseph L. Greathouse, Nuwan Jayasena, and Krishna Kavi. "DVFS Space Exploration in Power Constrained Processing-in-Memory Systems." In Architecture of Computing Systems - ARCS 2017, 221–33. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54999-6_17.

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Disser, Yann, and Max Klimm. "The Space Complexity of Undirected Graph Exploration." In Lecture Notes in Computer Science, 152–66. Cham: Springer Nature Switzerland, 2022. http://dx.doi.org/10.1007/978-3-031-21534-6_8.

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AbstractWe review the space complexity of deterministically exploring undirected graphs. We assume that vertices are indistinguishable and that edges have a locally unique color that guides the traversal of a space-constrained agent. The graph is considered to be explored once the agent has visited all vertices. We visit results for this setting showing that $$\varTheta \,(\log n)$$ Θ ( log n ) bits of memory are necessary and sufficient for an agent to explore all n-vertex graphs. We then illustrate that, if agents only have sublogarithmic memory, the number of (distinguishable) agents needed for collaborative exploration is $$\varTheta \,(\log \log n)$$ Θ ( log log n ) .
8

Chantrapornchai, Chantana, Wanlop Surakumpolthorn, and Edwin Sha. "Design Exploration Framework Under Impreciseness Based on Register-Constrained Inclusion Scheduling." In Advances in Computer Science - ASIAN 2004. Higher-Level Decision Making, 78–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-30502-6_6.

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Cao, Ruidong, Min Dong, Xuanlu Jiang, Sheng Bi, and Ning Xi. "Long-Horizon Route-Constrained Policy for Learning Continuous Control Without Exploration." In Lecture Notes in Computer Science, 38–49. Cham: Springer Nature Switzerland, 2022. http://dx.doi.org/10.1007/978-3-031-15931-2_4.

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Wang, Gui-hai, Tong-cui Guo, Hao-chen Li, Chun-qiu Guo, Hong-jun Wang, Jian-xiong Dong, and Liang-jie Zhang. "Thin Reef-Shoal Reservoir Prediction Using Two-Order Microfacies Constrained Geostatistical Inversion." In Proceedings of the International Field Exploration and Development Conference 2021, 1842–52. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2149-0_169.

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Conference papers on the topic "Constrained exploration":

1

Griffin, Brand Norman. "Lunar Daylight Exploration: Cost Constrained Human and Robotic Exploration." In 12th Biennial International Conference on Engineering, Construction, and Operations in Challenging Environments; and Fourth NASA/ARO/ASCE Workshop on Granular Materials in Lunar and Martian Exploration. Reston, VA: American Society of Civil Engineers, 2010. http://dx.doi.org/10.1061/41096(366)110.

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Woodcock, Gordon. "Space Exploration Strategies for Constrained Funding." In AIAA SPACE 2012 Conference & Exposition. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-5230.

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Jia, Fan, and Mei Han. "Bayesian optimization considering constrained boundary exploration." In 2023 4th International Conference on Big Data & Artificial Intelligence & Software Engineering (ICBASE). IEEE, 2023. http://dx.doi.org/10.1109/icbase59196.2023.10303125.

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Yang, Yong-Liang, Yi-Jun Yang, Helmut Pottmann, and Niloy J. Mitra. "Shape space exploration of constrained meshes." In the 2011 SIGGRAPH Asia Conference. New York, New York, USA: ACM Press, 2011. http://dx.doi.org/10.1145/2024156.2024158.

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Knödtel, Johannes, and Marc Reichenbach. "Datapath Optimization for Embedded Signal Processing Architectures utilizing Design Space Exploration." In DroneSE and RAPIDO 2023: System Engineering for constrained embedded systems. New York, NY, USA: ACM, 2023. http://dx.doi.org/10.1145/3579170.3579257.

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Jebali, Fatma, Oumaima Matoussi, Arief Wicaksana, Amir Charif, and Lilia Zaourar. "Decoupling processor and memory hierarchy simulators for efficient design space exploration." In DroneSE and RAPIDO '22: System Engineering for constrained embedded systems. New York, NY, USA: ACM, 2022. http://dx.doi.org/10.1145/3522784.3522796.

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Escuin, Carlos, Asif Ali Khan, Pablo Ibañez, Teresa Monreal, Victor Viñals, and Jeronimo Castrillon. "HyCSim: A rapid design space exploration tool for emerging hybrid last-level caches." In DroneSE and RAPIDO '22: System Engineering for constrained embedded systems. New York, NY, USA: ACM, 2022. http://dx.doi.org/10.1145/3522784.3522801.

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Carvalho, J., A. Malehmir, N. Pacheco, F. Marques, P. Dias, G. Donoso, B. Brodic, et al. "Target generations using constrained 3D gravity inversion and innovative in-mine-surface seismic surveys, Neves-Corvo, Portugal." In Mineral Exploration Symposium. European Association of Geoscientists & Engineers, 2020. http://dx.doi.org/10.3997/2214-4609.202089016.

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HasanzadeZonuzy, Aria, Dileep Kalathil, and Srinivas Shakkottai. "Model-Based Reinforcement Learning for Infinite-Horizon Discounted Constrained Markov Decision Processes." In Thirtieth International Joint Conference on Artificial Intelligence {IJCAI-21}. California: International Joint Conferences on Artificial Intelligence Organization, 2021. http://dx.doi.org/10.24963/ijcai.2021/347.

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In many real-world reinforcement learning (RL) problems, in addition to maximizing the objective, the learning agent has to maintain some necessary safety constraints. We formulate the problem of learning a safe policy as an infinite-horizon discounted Constrained Markov Decision Process (CMDP) with an unknown transition probability matrix, where the safety requirements are modeled as constraints on expected cumulative costs. We propose two model-based constrained reinforcement learning (CRL) algorithms for learning a safe policy, namely, (i) GM-CRL algorithm, where the algorithm has access to a generative model, and (ii) UC-CRL algorithm, where the algorithm learns the model using an upper confidence style online exploration method. We characterize the sample complexity of these algorithms, i.e., the the number of samples needed to ensure a desired level of accuracy with high probability, both with respect to objective maximization and constraint satisfaction.
10

Ramaithititima, Rattanachai, and Subhrajit Bhattacharya. "Landmark-based Exploration with Swarm of Resource Constrained Robots." In 2018 IEEE International Conference on Robotics and Automation (ICRA). IEEE, 2018. http://dx.doi.org/10.1109/icra.2018.8460884.

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Reports on the topic "Constrained exploration":

1

Rice, J., R. C. Paulen, M. Ross, M. B. McClenaghan, and H. E. Campbell. Quaternary geology of the southern Core Zone area, Quebec and Newfoundland and Labrador. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331426.

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The complex glacial geomorphology of east-central Quebec and western Labrador has resulted in conflicting ice-sheet reconstructions, leaving many questions regarding the behaviour of large ice sheets within their inner regions. Specifically, the ice-flow chronology and subglacial conditions remainpoorly constrained. To address this, surficial geology investigations were conducted across the border of Quebec and Labrador. A complex glacial history consisting of five ice-flow phases influenced by regional ice-stream dynamics was identified, including a near-complete ice-flow reversal. During each ice-flow phase, the subglacial thermal conditions fluctuated both spatially and temporally, resulting in palimpsest glacial dispersal patterns. Deglacial ages from samples collected as part of this research confirm deglaciation occurred relatively rapidly around 8 ka. The results of this work lead to a better understanding of the glacial history of an inner region of the Laurentide Ice Sheet and have important implications for mineral exploration in the southern Core Zone area.
2

Rice, J. M., R. C. Paulen, M. Ross, M. B. McClenaghan, and H E Campbell. Quaternary geology of the south Core Zone area, Quebec and Labrador. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330903.

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The complex glacial geomorphology of east-central Quebec and western Labrador has resulted in conflicting ice sheet reconstructions leaving many questions regarding the behaviour of large ice sheets within their inner regions. Specifically, the ice-flow chronology and subglacial conditions remain poorly constrained. To address this, surficial geology investigations were conducted across the border of Quebec and Labrador. A complex glacial history consisting of five ice-flow phases influenced by regional ice stream dynamics was identified, including a near-complete ice-flow reversal. During each ice-flow phase, the subglacial thermal conditions fluctuated both spatially and temporally, resulting in palimpsest glacial dispersal patterns. Deglacial ages from samples collected as part of this research confirm deglaciation occurred relatively rapidly around 8 ka. The results of this work improve our understanding of the glacial history of an inner region of the Laurentide Ice Sheet and have important implications for mineral exploration in the southern Core Zone area.
3

Rice, J. M., M. Ross, H E Campbell, R. C. Paulen, and M. B. McClenaghan. Net evolution of subglacial sediment transport in the Quebec-Labrador Sector of the Laurentide Ice Sheet, Quebec and Newfoundland and Labrador. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/332151.

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The interior of the Laurentide Ice Sheet (LIS) had a dynamic polythermal base. However, the subglacial thermal organization of the LIS and its evolution throughout glaciation are poorly constrained. Specifically, the net effect of ice divide migration on subglacial processes and the resulting landforms and sediments remains poorly understood. The results of a regional-scale till sampling program within the interior of the Quebec-Labrador sector of the LIS were used to explore dispersal patterns across a region known to have experienced ice divide migration. Indicator mineral and clast lithology analysis, coupled with multivariate analysis of the till matrix geochemistry, were used collectively, and evaluated within the context of the relative ice flow chronology and subglacial thermal evolution to augment our understanding of how ice divide migration impacts subglacial erosion and sedimentary processes. Indicator minerals (e.g., goethite and orthopyroxene) and clasts (e.g., iron formation clasts from the Labrador Trough) form glacial dispersal patterns that are consistent with the earliest northeast-trending ice-flow phase identified in the region. This early ice-flow phase produced and transported till across the entire study area (&amp;gt; 175 km). However, till matrix geochemistry shows a strong relationship with the local underlying bedrock, especially the major oxides. This relationship is relatively common in areas of thin till cover and resistant bedrock lithologies. The results also indicate that following the northeast ice-flow phase, erosion and till production became more localized, without considerable transport in a single sustained direction. These results are consistent with a transition to more sporadic warm-based conditions and ice divide migration, as ice sheet reconstructions indicate, and are supported by targeted 10Be data from erratics and bedrock surfaces. There are also spatial relationships between the dispersal of fresh or re-entrained debris and paleo-ice streams identified in the landform record, as evidenced by the dispersal of indicator minerals. The reworking of previously dispersed material during subsequent ice-flow phases resulted in complex dispersal patterns across the study area. These results provide important insights for ice sheet modelling and future mineral exploration programs in inner ice sheet regions of the LIS and demonstrate the importance of a thorough understanding of ice-flow history.
4

Berndt, Christian. RV SONNE Fahrtbericht / Cruise Report SO277 OMAX: Offshore Malta Aquifer Exploration, Emden (Germany) – Emden (Germany), 14.08. – 03.10.2020. GEOMAR Helmholtz Centre for Ocean Research Kiel, January 2021. http://dx.doi.org/10.3289/geomar_rep_ns_57_20.

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SO277 OMAX served two scientific projects. The objectives of the first project, SMART, were to develop multi-disciplinary methodologies to detect, quantify, and model offshore groundwater reservoirs in regions dominated by carbonate geology such as the Mediterranean Sea. To this end we acquired controlled-source electromagnetic, seismic, hydroacoustic, geochemical, seafloor imagery data off Malta. Preliminary evaluation of the geophysical data show that there are resisitivity anomalies that may represent offshore freshwater aquifers. The absence of evidence for offshore springs means that these aquifers would be confined and that it will be difficult to use them in a sustainable manner. The objective of the second project, MAPACT-ETNA, is to monitor the flank of Etna volcano on Sicily which is slowly deforming seaward. Here, we deployed six seafloor geodesy stations and six ocean bottom seismometers for long-term observation (1-3 years). In addition, we mapped the seafloor off Mt. Etna and off the island of Stromboli to constrain the geological processes that control volcanic flank stability.
5

Thomas, Douglas, and Mellon Michael. Sublimation of terrestrial permafrost and the implications for ice-loss processes on Mars. Engineer Research and Development Center (U.S.), July 2021. http://dx.doi.org/10.21079/11681/41244.

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Sublimation of ice is rate-controlled by vapor transport away from its outer surface and may have generated landforms on Mars. In ice-cemented ground (permafrost), the lag of soil particles remaining after ice loss decreases subsequent sublimation. Varying soil-ice ratios lead to differential lag development. Here we report 52 years of sublimation measurements from a permafrost tunnel near Fairbanks, Alaska, and constrain models of sublimation, diffusion through porous soil, and lag formation. We derive the first long-term in situ effective diffusion coefficient of ice-free loess, a Mars analog soil, of 9.05 × 10⁻⁶ m² s⁻¹, ~5× larger than past theoretical studies. Exposed ice-wedge sublimation proceeds ~4× faster than predicted from analogy to heat loss by buoyant convection, a theory frequently employed in Mars studies. Our results can be used to map near-surface ice-content differences, identify surface processes controlling landform formation and morphology, and identify target landing sites for human exploration of Mars.
6

D'Acosta, Michael, Karl Alexander Melgarejo, and Valerie Mercer-Blackman. Policy Benchmarking for Productivity and Growth: Review and Proposed Framework for the Caribbean. Inter-American Development Bank, September 2013. http://dx.doi.org/10.18235/0009131.

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This paper contributes to the analysis of the Caribbean's growth performance by setting out a framework for benchmarking indicators of key micro drivers and related structural policies that help explain differentials in productivity and real GDP per capita across the region, and relative to non-regional benchmark countries. The framework is adapted from the OECD's Going for Growth exercises. Its emphasis on micro-drivers in the labor market and the business environment aims to help shift the focus of the current discussions on growth from macroeconomic considerations (e.g. fiscal sustainability, exports) toward an exploration of productivity, which the literature identifies as the principal constraint to growth in the Caribbean and elsewhere. Potential advantages of a benchmarking-for-growth framework include knowledge sharing of the policies and performance indicators related to productivity in the Caribbean and appropriate benchmark countries. This could help stimulate further research and public discussion on the underlying factors behind the divergence in incomes as well as on the policies and environments that contribute to those differentials. An initial exercise highlights issues with restrictions for starting a business, the tax burden, the cost of imports and infrastructure deficiencies as potential barriers to growth.
7

de Caritat, Patrice, Brent McInnes, and Stephen Rowins. Towards a heavy mineral map of the Australian continent: a feasibility study. Geoscience Australia, 2020. http://dx.doi.org/10.11636/record.2020.031.

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Heavy minerals (HMs) are minerals with a specific gravity greater than 2.9 g/cm3. They are commonly highly resistant to physical and chemical weathering, and therefore persist in sediments as lasting indicators of the (former) presence of the rocks they formed in. The presence/absence of certain HMs, their associations with other HMs, their concentration levels, and the geochemical patterns they form in maps or 3D models can be indicative of geological processes that contributed to their formation. Furthermore trace element and isotopic analyses of HMs have been used to vector to mineralisation or constrain timing of geological processes. The positive role of HMs in mineral exploration is well established in other countries, but comparatively little understood in Australia. Here we present the results of a pilot project that was designed to establish, test and assess a workflow to produce a HM map (or atlas of maps) and dataset for Australia. This would represent a critical step in the ability to detect anomalous HM patterns as it would establish the background HM characteristics (i.e., unrelated to mineralisation). Further the extremely rich dataset produced would be a valuable input into any future machine learning/big data-based prospectivity analysis. The pilot project consisted in selecting ten sites from the National Geochemical Survey of Australia (NGSA) and separating and analysing the HM contents from the 75-430 µm grain-size fraction of the top (0-10 cm depth) sediment samples. A workflow was established and tested based on the density separation of the HM-rich phase by combining a shake table and the use of dense liquids. The automated mineralogy quantification was performed on a TESCAN® Integrated Mineral Analyser (TIMA) that identified and mapped thousands of grains in a matter of minutes for each sample. The results indicated that: (1) the NGSA samples are appropriate for HM analysis; (2) over 40 HMs were effectively identified and quantified using TIMA automated quantitative mineralogy; (3) the resultant HMs’ mineralogy is consistent with the samples’ bulk geochemistry and regional geological setting; and (4) the HM makeup of the NGSA samples varied across the country, as shown by the mineral mounts and preliminary maps. Based on these observations, HM mapping of the continent using NGSA samples will likely result in coherent and interpretable geological patterns relating to bedrock lithology, metamorphic grade, degree of alteration and mineralisation. It could assist in geological investigations especially where outcrop is minimal, challenging to correctly attribute due to extensive weathering, or simply difficult to access. It is believed that a continental-scale HM atlas for Australia could assist in derisking mineral exploration and lead to investment, e.g., via tenement uptake, exploration, discovery and ultimately exploitation. As some HMs are hosts for technology critical elements such as rare earth elements, their systematic and internally consistent quantification and mapping could lead to resource discovery essential for a more sustainable, lower-carbon economy.
8

McMartin, I., M. S. Gauthier, and A. V. Page. Updated post-glacial marine limits along western Hudson Bay, central mainland Nunavut and northern Manitoba. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330940.

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A digital compilation of updated postglacial marine limits was completed in the coastal regions of central mainland Nunavut and northern Manitoba between Churchill and Queen Maud Gulf. The compilation builds on and updates previous mapping of the marine limits at an unprecedented scale, making use of high-resolution digital elevation models, new field-based observations of the marine limit and digital compilations of supporting datasets (i.e. marine deltas and marine sediments). The updated mapping also permits a first-hand, knowledgedriven interpolation of a continuous limit of marine inundation linking the Tyrrell Sea to Arctic Ocean seawaters. The publication includes a detailed description of the mapping methods, a preliminary interpretation of the results, and a GIS scalable layout map for easy access to the various layers. These datasets and outputs provide robust constraints to reconstruct the patterns of ice retreat and for glacio-isostatic rebound models, important for the estimation of relative sea level changes and impacts on the construction of nearshore sea-transport infrastructures. They can also be used to evaluate the maximum extent of marine sediments and associated permafrost conditions that can affect land-based infrastructures, and potential secondary processes related to marine action in the surficial environment and, therefore, can enhance the interpretation of geochemical anomalies in glacial drift exploration methods. A generalized map of the maximum limit of postglacial marine inundation produced for map representation and readability also constitutes an accessible output relevant to Northerners and other users of geoscience data.
9

Ferguson, Thomas, and Servaas Storm. Myth and Reality in the Great Inflation Debate: Supply Shocks and Wealth Effects in a Multipolar World Economy. Institute for New Economic Thinking Working Paper Series, January 2023. http://dx.doi.org/10.36687/inetwp196.

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This paper critically evaluates debates over the causes of U.S. inflation. We first show that claims that the Biden stimulus was the major cause of inflation are mistaken: the key data series – stimulus spending and inflation – move dramatically out of phase. While the first ebbs quickly, the second persistently surges. We then look at alternative explanations of the price rises. We assess four supply side factors: imports, energy prices, rises in corporate profit margins, and COVID. We argue that discussions of COVID’s impact have thus far only tangentially acknowledged the pandemic’s far-reaching effects on labor markets. We conclude that while all four factors played roles in bringing on and sustaining inflation, they cannot explain all of it. There really is an aggregate demand problem. But the surprise surge in demand did not arise from government spending. It came from the unprecedented gains in household wealth, particularly for the richest 10% of households, which we show powered the recovery of aggregate US consumption expenditure especially from July 2021. The final cause of the inflationary surge in the U.S., therefore, was in large measure the unequal (wealth) effects of ultra-loose monetary policy during 2020-2021. This conclusion is important because inflationary pressures are unlikely to subside soon. Going forward, COVID, war, climate change, and the drift to a belligerently multipolar world system are all likely to strain global supply chains. Our conclusion outlines how policy has to change to deal with the reality of steady, but irregular supply shocks. This type of inflation responds only at enormous cost to monetary policies, because it arises mostly from supply-side difficulties that require targeted solutions. But when supply plummets or becomes more variable, fiscal policy also has to adapt: existing explorations of ways to steady demand over the business cycle have to embrace much bolder macroeconomic measures to control over-spending when supply is temporarily constrained.

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