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Academic literature on the topic 'Contractional system'

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Published: 1 April 2023

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Journal articles on the topic "Contractional system"

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Miller, Robert B., and Scott R. Paterson. "Tectonic implications of syn- and post-emplacement deformation of the Mount Stuart batholith for mid-Cretaceous orogenesis in the North Cascades." Canadian Journal of Earth Sciences 29, no. 3 (March 1, 1992): 479–85. http://dx.doi.org/10.1139/e92-041.

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The 93–96 Ma Mount Stuart batholith intruded across the boundary between the Northwest Cascades thrust system and the crystalline core of the North Cascades. Although previously considered posttectonic, the northeast margin of the Mount Stuart batholith and its wall rocks have been involved in syn- to post-emplacement, southwest-directed thrusting and folding, and west-northwest stretching. Contraction ended shortly after emplacement, as indicated by high-temperature recrystallization in thrust-related mylonites of the pluton and by geochronological data, whereas west-northwest stretching continued for an unknown period of time. This is the best documented mid-Cretaceous contractional belt in the main part of the crystalline core. The shortening direction and timing are identical to that of southwest-vergent thrusts in the offset continuation of the core in British Columbia. The contractional belt provides a link between thrusting in the Northwest Cascades thrust system and deformation in the crystalline core.
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Gomes, Caroline J. S., Marcelo A. Martins-Neto, and Valéria E. Ribeiro. "Positive inversion of extensional footwalls in the southern Serra do Espinhaço, Brazil - insights from sandbox laboratory experiments." Anais da Academia Brasileira de Ciências 78, no. 2 (June 2006): 331–44. http://dx.doi.org/10.1590/s0001-37652006000200012.

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Analogue experiments were carried out to get insights into the processes governing positive inversion during the foreland propagating thrust tectonics in the southern Serra do Espinhaço, a Brasiliano/Panafrican foldthrust belt in southeast Brazil. In particular, model listric half-grabens were inverted by applying contractional displacement to the footwall blocks. We investigated two different inversion conditions in listric half-grabens: (i) extensional and contractional detachments at the same level and (ii) at different positions. The models revealed that the development of a forward-breaking thrust system occurs in the basin synrift deposits, by contractional translation of the extensional footwall block when the extensional and contractional master faults do not coincide. Our experiments show the tectonic imbrication between basement and synrift sequences which characterizes the southern Serra do Espinhaço, and support the location in the eastern mountain range domain of the Espinhaço rift master fault system, which is not exposed at the surface.
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Najafi, Mahdi, and Sahar Lajmorak. "Contractional salt-tectonic system in the south Dezful embayment, Zagros." Journal of Structural Geology 141 (December 2020): 104204. http://dx.doi.org/10.1016/j.jsg.2020.104204.

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Krisnabudhi, Alfathony, Benyamin Sapiie, Agus Men Riyanto, Adi Gunawan, and Febriana Fiona Rizky. "Mesozoic-Cenozoic Stratigraphy and Tectonic Development of the Southern Great Tarakan Basin, Northeast Borneo, Indonesia." Rudarsko-geološko-naftni zbornik 37, no. 1 (2022): 123–38. http://dx.doi.org/10.17794/rgn.2022.1.11.

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We analyzed the tectonics and stratigraphy of the Southern Great Tarakan Basin to determine its tectonic evolution during the Mesozoic-Cenozoic Eras, the evolution of basin geometry, and the potential of hydrocarbon using integrated surface and subsurface data. Southern Great Tarakan Basin can be divided into three sub-basins, Berau, Muara, and South Tarakan. They comprise deposits of Jurassic to Quaternary age, which can be assigned five mega sequences based on their lithological characteristics and tectonic development. We divide the tectonic events into four main phases; (1) contractional Jurassic-Cretaceous, (2) extensional Paleogene, (3) subsidence Early Neogene, and (4) contractional Late Neogene. The development of the strike-slip activity influenced the geometric evolution of the two sub-basins. NW-SE transpressional structures formed during the contraction phase caused most of the existing structure in Paleogene reactivated and inverted, followed by basement uplift and erosion. Consequently, the evolution of the transpressional system caused The Great Tarakan Basin to be divided into five sub-basins during the Late Miocene-Pliocene. Moreover, five horizons with hydrocarbon potential exist in the southern part of The Greater Tarakan Basin; three plays in the Berau Sub-basin, and two main plays in the Muara Sub-basin. The Late Neogene structures in the Berau Sub-basin control the accumulation, migration, and trapping mechanism, whereas these structures do not exist in Muara; hence, this sub-basin is dominated by stratigraphic traps.
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Franzese, Juan R., Leandro D’Elia, Andres Bilmes, Martin Muravchik, and Mariano Hernandez. "Superimposition of oligo-miocene extensional and contractional basins in the northpatagonian Andean retroarc: The Alumine Basin, Neuquen, Argentina." Andean Geology 38, no. 2 (August 9, 2011): 319. http://dx.doi.org/10.5027/andgeov38n2-a04.

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The Alumine Basin is a volcano-sedimentary depocentre located in the Andean retroarc at 39°S. It is the southern part of a major depositional system: the Bio Bio-Alumine Basin. Stratigraphical, geochronological, sedimentological and structural analysis allow us to conclude that the basin evolved through two stages: an Oligocene extensional stage filled with basalts and reworked volcaniclastic and pyroclastic deposits (Rancahue Formation) and a Miocene contractional stage, filled with alluvial and pyroclastic deposits covered by basaltic lavas (Chimehuin and Tipilihuque formations). The volcanic-rich (basaltic) infill of the extensional stage has a western provenance and was derived from widespread magmatic activity that took place during the Oligocene in the adjacent cordilleran axis. The contractional stage basin is an intramontane depocentre limited by uplifted blocks generated mainly by the inversion of Mesozoic extensional faults. It is strongly asymmetric and shows eastern provenance. Structural and geomorphological evidence indicate the existence of a non-depositional hiatus between the two stages.
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Favorito, Daniel A., and Eric Seedorff. "Laramide Uplift near the Ray and Resolution Porphyry Copper Deposits, Southeastern Arizona: Insights into Regional Shortening Style, Magnitude of Uplift, and Implications for Exploration." Economic Geology 115, no. 1 (January 1, 2020): 153–75. http://dx.doi.org/10.5382/econgeo.4697.

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Abstract This study integrates new geologic mapping and structural analysis with previous work near Walnut Canyon and Telegraph Canyon to address the style and magnitude of shortening and the relationship between contractional structures and porphyry preservation and localization between the Ray and Resolution porphyry copper deposits. Cenozoic extensional structures were superimposed on earlier contractional structures formed during the Laramide orogeny, which dates from ~80 to 50 Ma. This superposition requires that Cenozoic normal faults be restored prior to analysis of Laramide contractional structures and their relationship to nearby porphyry copper deposits. Five distinct sets of normal faults within the study area progressively tilted the region 65° east. The amount of extension was 10.3 km or 276%. Using key constraints such as offset strata, cutoff angles between faults and various units, and Laramide fault geometries, the study area was structurally reconstructed and verified using 2-D kinematic modeling of reverse fault offset and related folding. Total shortening is 7.2 km or 98%. Laramide reverse faults are interpreted as thick-skinned basement-cored uplifts, because they restore to moderate angles, have related fault-propagation folds, and involve significant crystalline basement rock. The Telegraph Canyon reverse fault has at least 5.3 km of offset, and the Walnut Canyon reverse fault has 3.2 km. The preferred estimate of the total vertical uplift for the fault system is 5.2 km but could be several kilometers greater. The restored strike direction of these faults combined with mid-Cenozoic erosion surfaces throughout the region suggests that this fault system may be responsible for the Laramide uplift of the Tortilla Mountains and Black Hills. In addition, most major porphyry centers appear to have been intruded into the footwall of this large uplift, with local examples including Ray and Resolution, suggesting that topography generated from this uplift may have been critical to preservation of these ore systems. Though definitive crosscutting relationships do not exist in the immediate map area, geologic relationships in a broader area suggest that shortening here began after 74 Ma and, in the Ray area, had ended by ~69 Ma and that porphyry formation postdated reverse faulting by as much as 5 m.y. to as little as <1 m.y.
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Miller, Robert B. "A mid-crustal contractional stepover zone in a major strike-slip system, North Cascades, Washington." Journal of Structural Geology 16, no. 1 (January 1994): 47–60. http://dx.doi.org/10.1016/0191-8141(94)90017-5.

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Mora, Andrés, Wilson Casallas, Richard A. Ketcham, Diego Gomez, Mauricio Parra, Jay Namson, Daniel Stocklie, Ariel Almendral, Wilmer Robles, and Badr Ghorbal. "Kinematic restoration of contractional basement structures using thermokinematic models: A key tool for petroleum system modeling." AAPG Bulletin 99, no. 08 (August 2015): 1575–98. http://dx.doi.org/10.1306/04281411108.

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Brankman, Charles M., and Atilla Aydin. "Uplift and contractional deformation along a segmented strike-slip fault system: the Gargano Promontory, southern Italy." Journal of Structural Geology 26, no. 5 (May 2004): 807–24. http://dx.doi.org/10.1016/j.jsg.2003.08.018.

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Fetrow, Anne C., Kathryn E. Snell, Russell V. Di Fiori, Sean P. Long, and Joshua W. Bonde. "Early Sevier orogenic deformation exerted principal control on changes in depositional environment recorded by the Cretaceous Newark Canyon Formation." Journal of Sedimentary Research 90, no. 9 (September 1, 2020): 1175–97. http://dx.doi.org/10.2110/jsr.2020.52.

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ABSTRACT Terrestrial sedimentary archives record critical information about environment and climate of the past, as well as provide insights into the style, timing, and magnitude of structural deformation in a region. The Cretaceous Newark Canyon Formation, located in central Nevada, USA, was deposited in the hinterland of the Sevier fold–thrust belt during the North American Cordilleran orogeny. While previous research has focused on the coarser-grained, fluvial components of the Newark Canyon Formation, the carbonate and finer-grained facies of this formation remain comparatively understudied. A more complete understanding of the Newark Canyon Formation provides insights into Cretaceous syndeformational deposition in the Central Nevada thrust belt, serves as a useful case study for deconvolving the influence of tectonic and climatic forces on sedimentation in both the North American Cordillera and other contractional orogens, and will provide a critical foundation upon which to build future paleoclimate and paleoaltimetry studies. We combine facies descriptions, stratigraphic measurements, and optical and cathodoluminescence petrography to develop a comprehensive depositional model for the Newark Canyon Formation. We identify six distinct facies that show that the Newark Canyon Formation evolved through four stages of deposition: 1) an anastomosing river system with palustrine interchannel areas, 2) a braided river system, 3) a balance-filled, carbonate-bearing lacustrine system, and 4) a second braided river system. Although climate undoubtedly played a role, we suggest that the deposition and coeval deformation of the synorogenic Newark Canyon Formation was in direct response to the construction of east-vergent contractional structures proximal to the type section. Comparison to other contemporary terrestrial sedimentary basins deposited in a variety of tectonic settings provides helpful insights into the influences of regional tectonics, regional and global climate, catchment characteristics, underlying lithologies, and subcrop geology in the preserved sedimentary record.
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Dissertations / Theses on the topic "Contractional system"

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Lohmiller, Winfried Stefan 1971. "Contraction analysis of nonlinear systems." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9793.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.
Includes bibliographical references (leaves 87-90).
This thesis derives new results in nonlinear system analysis using methods inspired from fluid mechanics and differential geometry. Based on a differential analysis of convergence, these results may be viewed as generalizing the classical Krasovskii the­orem, as well as linear eigenvalue analysis. A central feature is that convergence and limit behavior are in a sense treated separately, leading to significant conceptual simplifications. We establish new combination properties of nonlinear dynamic systems and use them to derive simple controller and observer designs for mechanical systems such as aircraft, underwater vehicles, and robots. The method is also applied to chemical chain reactions and mixture processes. The relative simplicity of these designs stems from their effective exploitation of the systems' structural specificities. Next, we analyze and quantify the global stability properties of physical partial differential equations such as the heat equation, or the Schroedinger equation. Lyapunov exponents are not coordinate-invariant, and thus their exact physical meaning is somewhat questionable. As an alternative, we suggest an extension of linear eigenvalue analysis to nonlinear dynamic systems. Finally, the thesis derives new controller and observer designs for general nonlinear dynamic systems. In particular, an extension of feedback linearization is proposed when the corresponding integrability conditions are violated.
by Winfried Stefan Lohmiller.
Ph.D.
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Borja, da rocha Hudson. "Collective effects in muscle contraction and cellular adhesion." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX072/document.

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Deux systèmes biologiques distincts, les muscles squelettiques et les sites d'adhésion de cellules kératocytes en mouvement, sont considérés dans un même cadre en raison de la similitude profonde de leur structure et de leur fonctionnalité. La réponse passive de l'un et de l'autre peut être modélisée à l'aide d'un grand nombre d'unités multi-stables couplées par des interactions à longue portée, et exposées à un désordre spatial fixé et un bruit thermique/mécanique. Les interactions à longue portée dans de tels systèmes conduisent à une synchronisation malgré les fluctuations temporelles et spatiales. Bien que les deux systèmes biologiques considérés présentent des différences structurelles importantes, nous montrons que l'on peut identifier une structure de verre de spin sous-jacente commune. À la lumière de cette analogie, ces systèmes vivants semblent être proches de points critiques et, à cet égard, le désordre gelé, reflétant l’incommensurabilité stérique des unités parallèles, peut être fonctionnel. Un autre paramètre important fixant la réponse est la rigidité interne du système qui couple les unités entre elles
Two biological systems, a half-sarcomere of a skeletal muscle and an adhesive cluster of a crawling keratocyte, are considered in parallel because of the deep similarity in their structure and functionality. Their passive response can be modeled by a large number of multi-stable units coupled through long-range interactions, frustrated by quenched disorder and exposed to thermal noise. In such systems, long-range interactions lead to synchronization, defying temporal and spatial fluctuations. We use a mean-field description to obtain analytic results and elucidate the remarkable ensemble-dependence of the mechanical behavior of such systems in the thermodynamic limit. Despite important structural differences between muscle cross-bridges and adhesive binders, one can identify a common underlying spin glass structure, which we fully exploit in this work. Our study suggests that the muscle machinery is fine-tuned to operate near criticality, and we argue that in this respect the quenched disorder, reflecting here steric incommensuration, may be functional. We use the analogy between cell detachment and thermal fracture of disordered solids to study the statistics of fluctuations during cellular adhesion. We relate the obtained results to recent observations of intermittent behavior involved in cell debonding, also suggesting near-criticality. In addition to the study of the equilibrium properties of adhesive clusters, we also present the first results on their kinetic behavior in the presence of time-dependent loading
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Reis, Maurício Duarte Luís. "On theory multiple contraction." Doctoral thesis, Universidade da Madeira, 2011. http://hdl.handle.net/10400.13/255.

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The one which is considered the standard model of theory change was presented in [AGM85] and is known as the AGM model. In particular, that paper introduced the class of partial meet contractions. In subsequent works several alternative constructive models for that same class of functions were presented, e.g.: safe/kernel contractions ([AM85, Han94]), system of spheres-based contractions ([Gro88]) and epistemic entrenchment-based contractions ([G ar88, GM88]). Besides, several generalizations of such model were investigated. In that regard we emphasise the presentation of models which accounted for contractions by sets of sentences rather than only by a single sentence, i.e. multiple contractions. However, until now, only two of the above mentioned models have been generalized in the sense of addressing the case of contractions by sets of sentences: The partial meet multiple contractions were presented in [Han89, FH94], while the kernel multiple contractions were introduced in [FSS03]. In this thesis we propose two new constructive models of multiple contraction functions, namely the system of spheres-based and the epistemic entrenchment-based multiple contractions which generalize the models of system of spheres-based and of epistemic entrenchment-based contractions, respectively, to the case of contractions (of theories) by sets of sentences. Furthermore, analogously to what is the case in what concerns the corresponding classes of contraction functions by one single sentence, those two classes are identical and constitute a subclass of the class of partial meet multiple contractions. Additionally, and as the rst step of the procedure that is here followed to obtain an adequate de nition for the system of spheres-based multiple contractions, we present a possible worlds semantics for the partial meet multiple contractions analogous to the one proposed in [Gro88] for the partial meet contractions (by one single sentence). Finally, we present yet an axiomatic characterization for the new class(es) of multiple contraction functions that are here introduced.
Eduardo Fermé
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Rajayogan, Vinod Engineering &amp Information Technology Australian Defence Force Academy UNSW. "Autogenous shrinkage in cementitious systems." Awarded by:University of New South Wales - Australian Defence Force Academy. Engineering & Information Technology, 2009. http://handle.unsw.edu.au/1959.4/44250.

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Autogenous shrinkage is of concern in high performance concrete mixtures, when specific properties like strength and durability are enhanced. Factors like low watercement ratio, low porosity and increased hydration kinetics which are associated with high performance concrete mixtures are also responsible for the development of autogenous shrinkage. With about two decades of research into autogenous shrinkage, uncertainties still exist with testing procedure, effect of supplementary cementitious materials, modelling and prediction of autogenous shrinkage. The primary focus of this study is to understand mechanisms which have been postulated to cause autogenous shrinkage like chemical shrinkage and self desiccation. In addition, this study has considered properties like porosity and internal empty voids in the analysis of the causes of bulk volume deformations of the cementitious paste systems with and without mineral admixtures. The study begins with an experimental investigation of chemical shrinkage in hydrating cementitious paste systems with the addition of fly ash, slag and silica fume using the test method recently accepted by the ASTM. This was followed by the experimental investigation of autogenous shrinkage in cementitious paste. The autogenous shrinkage in paste mixtures is studied from an early age (~1.5 hours after addition of water) for cementitious systems at a water-cementitious ratio of 0.32 (w/c 0.25 for limited mixture proportions). A non-contact measurement method using eddy current sensors were adopted. The hydration mechanism of the cementitious paste systems was then modelled using CEMHYD3D, which is a 3 dimensional numerical modelling method successfully used to study, simulate and present the hydration developments in cementitious systems. Properties like chemical shrinkage, degree of hydration, total porosity and free water content; all of which have been obtained from the CEMHYD3D simulation have been cross correlated with the experimental results in order to more comprehensively understand the mechanism contributing to bulk volume change under sealed conditions. The experimental investigations are extended to study the development in concrete with and without mineral admixtures (i.e., silica fume, fly ash and slag). Self desiccation driving the development of autogenous shrinkage has been used extensively across literature but as an alternative the author has proposed using internal drying factor in modelling autogenous shrinkage. The "internal drying factor" is described as the ratio of the empty voids (due to chemical shrinkage) to the total porosity at any point of time of hydration. Independent of the mixture proportions, a linear trend was observed between the autogenous shrinkage strain and increase in internal drying factor. Thus the internal drying factor could be incorporated into semiempirical models while attempting to predict autogenous shrinkage. An increase in the compressive strength of matured concrete at 1 year had a strong correlation to the observed autogenous shrinkage strains irrespective of the cementitious system. It is believed this could be because of the increase in gel-space ratio which is intern linked to the degree of hydration and porosity of the microstructure. The author has obtained strong evidence that the micro-structural changes associated with high strength and durable concrete have a direct impact on the autogenous shrinkage of concrete. Hence, the author suggests that autogenous shrinkage should be investigated and allowable values be stipulated as design criterion in structures that use high strength-high performance concrete.
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Mikulenka, Martin. "Technologie výroby plastové pružné spony." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229926.

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Currently, the plastics industry has a wide range of applications due to the possibility of a fully automated process or through increased production efficiencies. The reason for this choice of the thesis was to understand the whole issue of plastic injection molding process. The specified component is used to atach the sail, which serves to protect workers in the welding sector. A specified number of the series is 350 000. The work includes a theoretical problem of injection molding process, selection of technology, material selection and design of mold. An integral part of every design mold is a simulation of injection, which is also included. In conclusion of thesis is the calculation of the various stages of production and operation of the injection mold.
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Rababy, Nada. "Estimation of EMG conduction velocity using system identification." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63819.

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Jaramillo, Cienfuegos Paola. "Closed Loop Control of Muscle Contraction using Functional Electrical Stimulation." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78471.

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A promising approach to treat patients with vocal fold paralysis using electrical stimulation is investigated throughout this research work. Functional Electrical Stimulation works by stimulating the atrophied muscle or group of muscles directly by current when the transmission lines between the central nervous system are disrupted. This technique helps maintain muscle mass and promote blood flow in the absence of a functioning nervous system. The goal of this work is two-fold: develop control techniques for muscle contraction to optimize muscle stimulation and develop a small-scale electromagnetic system to provide stimulation to the laryngeal muscles for patients with vocal fold paralysis. These studies; therefore, focus on assessing a linear Proportional-Integral (PI) controller and two nonlinear controllers: Model Reference Adaptive Controller (MRAC) and an Adaptive Augmented PI (ADP-PI) system to identify the most appropriate controller providing effective stimulation of the muscle. Direct stimulation is applied to mouse skeletal muscle in vitro to test the controllers along with numerical simulations for validation of these experimental tests. The experiments included muscle contractions following four distinct trajectories: a step, sine, ramp, and square wave. Overall, the closed-loop controllers followed the stimulation trajectories set for all the simulated and tested muscles. When comparing the experimental outcomes of each controller, we concluded that the ADP-PI algorithm provided the best closed-loop performance for speed of convergence and disturbance rejection. Next, the focus of the research work was on the implementation of an electromagnetic system to generate appropriate currents of stimulation using the aforementioned controllers. For this study, Nickel-Titanium shape memory alloys were used to assess activation (contraction) through a two-coil system guided by the controllers. The application of the two-coil system demonstrated the effectiveness of the approach and a main effect was observed between the PI, MRAC, and ADP-PI controllers when following the trajectories. Lastly, a small scale two-coil system is developed for animal testing in the muscle-mass-spring setup. Experiments were successful in generating the appropriate stimulation controlled by the output-based algorithms for muscle contraction. Trials conducted for this study were compared to the muscle contractions observed in the first study. The controllers were able to provide appropriate stimulation to the muscle system to follow the set trajectories: a step, ramp, and sinusoidal input. More trials are required to draw statistical conclusions about the performance of each controller. Regardless, the small-scale two-coil system along with the applied controllers can be reconfigured to be an implantable system and tested for appropriate stimulation of the laryngeal muscles.
Ph. D.
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Fox, Jane. "Utility of the precision cut lung slice model to investigate airway smooth muscle contraction." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/30380/.

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Asthma is characterised by airway remodelling and an increase in airway resistance. A greater understanding of the mechanisms involved in airway inflammation and airway hyper-responsiveness (AHR) may highlight therapeutic opportunities for asthma. This study initially aimed to optimise the preparation of precision cut lung slices (PCLS) in mouse and pig to investigate the influence of calcium (Ca2+) homeostasis on airway smooth muscle (ASM) contraction as a prelude to human studies. The PCLS technique was then applied to a murine model of allergic airway disease to explore the inflammatory process and pathogenesis of airway hyper-reactivity in sensitised mice. Initial experiments using murine and porcine airways validated the PCLS model and demonstrated the significance of release and refilling of Ca2+ from internal stores to induce and maintain an airway contraction. Results also highlight interesting species differences in agonist sensitivity, with the porcine system sharing similar pharmacology to human airways. Using a murine model of allergic airway disease, agonist induced contractile responses in peripheral airways were measured in vitro using the PCLS technique. BALB/c mice underwent initial sensitisation by intraperitoneal administration of ovalbumin, receiving a 3 day challenge with aerosolised OVA l% (vlv), for varying periods of up to 3 weeks for acute, mid-chronic and chronic sensitisation protocols. To investigate the influence of the inflammatory environment, naive murine lung slices were incubated with selected inflammatory mediators. OVA sensitisation led to progressive structural remodelling and AHR to methacholine (MCh) challenge. However, this hyperresponsiveness was decreased 48 hours post lung removal. Of the inflammatory mediators selected for lung slice incubation, IL-33 significantly increased AHR to MCh. IL-33 is a proinflammatory cytokine with transcriptional repressor properties, playing a role in initiating the TH2 inflammatory response. In lung slices prepared from IL-33 receptor (ST2) KO mice IL-33 was unable to sensitise the contractile response. These data suggest the inflammatory environment promotes AHR and disassociates this airway sensitivity from structural remodelling. These data suggest a key role for IL-33 in mediating AHR in this murine model. Investigation of the mechanisms involved in airway hyper-reactivity revealed mRNA expression of IL-33 and the IL-33 receptor (ST2) in soluble and membrane bound forms were significantly increased in the mid-chronic and chronic ovalbumin sensitised murine lung tissue. Further quantitative analysis in human lung showed expression of IL-33 in epithelial and ASM cells. The human ST2 receptor (also known as IL-IRL-l) was expressed in mast cells. Together these results suggest IL-33 is a sensor of tissue damage; indirectly inducing AHR through further inflammatory cell activation to target ASM. This study demonstrates IL-33's role as an inflammatory marker of asthma and suggests a novel therapeutic intervention by targeting of the ST2 receptor.
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Wandler, Jeff. "Calculating Cardiovascular Lumped-Parameter Model Values by Injecting Small Volume Perturbations in an Isovolumic Heart." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/28884.

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Diagnosing cardiac patient problems contains many uncertainties, and to fully diagnose the patient's condition usually requires a lengthy drug regimen to see what works and what does not. Compounding this problem is that even after the correct drug regimen has been discovered, the underlying cause for the problem may remain a mystery. Thus, the uncertainty and the length of time required to provide an accurate and adequate solution makes it very difficult to provide quality care to the patient. Templeton and others have shown that lumped cardiac muscle parameters can be extracted from an isolated heart by injecting small volumes at high frequencies relative to the heart rate and measuring the pressure response to this volume change. Using the Hill muscle model of two springs and a dash pot to portray the different elements of the cardiac muscle, the pressure and volume relationship makes it possible to calculate these muscle parameters using frequency response analysis techniques. The hypothesis to be tested is "Is it possible to develop a method to test cardiac muscle for stiffness, resistance, and contractile force from measuring ventricular pressure and injected flow?" To test this hypothesis, an isovolumic heart model is developed and allowed to develop pressure, along with a small volume injected to create a pressure response. Analysis of the pressure and flow waveforms produces a measured value of the cardiac model parameter values to compare to the model values. Results from injecting small volume changes into a mathematical heart model show that it is possible to extract the muscle model parameters of non-linear resistance, inertia of the fluid and muscle, and stiffness of the muscle while filling and contracting. The injected frequency and volume were varied to find usable conditions, both with regard to the calculations and the practical limits. Analyzing the error between the measured and model values for a large number of different combinations of model parameters shows an average error of less than 1%.
Iron Range Engineering
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Mehrle, Yvonne E. "Solidification and contraction of confectionery systems in rapid cooling processing." lizenzfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:30497.

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Books on the topic "Contractional system"

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1922-, Ebashi Setsurō, and Ohtsuki Iwao, eds. Regulatory mechanisms of striated muscle contraction. Tokyo: Springer, 2007.

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R, Amundsen Louis, ed. Muscle strength testing: Instrumented and non-instrumented systems. New York: Churchill Livingstone, 1990.

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Matti, Weckström, and Tavi Pasi, eds. Cardiac mechanotransduction. Austin, TX: Landes Bioscience/Eurekah.com, 2007.

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Hughes, Gwendoline Ann. Modulation of spontaneous contraction in ovine and bovine lymphatic systems. [S.l: The Author], 1992.

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Hemmling, Gerlinde. Anpassungen des neuromuskulären Systems an eine neuentwickelte Trainingsmethode. Köln: Bundesinstitut für Sportwissenschaft, 1994.

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Ran, Shi-Ju. Tensor Network Contractions: Methods and Applications to Quantum Many-Body Systems. Cham: Springer Nature, 2020.

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T, Kappagoda C., Kaufman Marc P, and Symposium on Control of the Cardiovascular and Respiratory Systems in Health and Disease (1994 : University of California, Davis), eds. Control of the cardiovascular and respiratory systems in health and disease. New York: Plenum Press, 1995.

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Kohl, Peter. Cardiac mechano-electric coupling and arrhythmias. 2nd ed. Oxford: Oxford University Press, 2011.

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Kohl, Peter. Cardiac mechano-electric feedback and arrhythmias: From pipette to patient. Philadelphia, PA: W.B. Saunders, 2005.

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J, Aidley David, ed. Nerve and muscle. 3rd ed. Cambridge: Cambridge University Press, 2001.

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Book chapters on the topic "Contractional system"

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Devasahayam, Suresh R. "Skeletal Muscle Contraction." In Signals and Systems in Biomedical Engineering, 225–52. Boston, MA: Springer US, 2012. http://dx.doi.org/10.1007/978-1-4614-5332-1_10.

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Russo, Giovanni, Mario di Bernardo, and Jean Jacques Slotine. "Contraction Theory for Systems Biology." In Design and Analysis of Biomolecular Circuits, 93–114. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6766-4_5.

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Luxoro, Mario, Verónica Nassar-Gentina, and Eduardo Rojas. "Excitation-Contraction Coupling in Barnacle Muscle Fibers: Does Calcium Entry Trigger Contraction Directly?" In Transduction in Biological Systems, 289–300. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-5736-0_20.

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Tsalapati, Eleni, Giorgos Stoilos, Giorgos Stamou, and George Koletsos. "Query Rewriting under Ontology Contraction." In Web Reasoning and Rule Systems, 172–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-33203-6_13.

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Jacob, Birgit, and Hans J. Zwart. "Contraction and Unitary Semigroups." In Linear Port-Hamiltonian Systems on Infinite-dimensional Spaces, 65–77. Basel: Springer Basel, 2012. http://dx.doi.org/10.1007/978-3-0348-0399-1_6.

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Ciabattoni, Agata. "Bounded Contraction in Systems with Linearity." In Lecture Notes in Computer Science, 113–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-48754-9_13.

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Arratia, O., M. Gadella, and M. A. del Olmo. "Group Contractions and Stratonovich-Weyl Kernels." In Quantization and Infinite-Dimensional Systems, 147–53. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2564-6_17.

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Devasahayam, Suresh R. "Skeletal Muscle Contraction: Force and Movement." In Signals and Systems in Biomedical Engineering: Physiological Systems Modeling and Signal Processing, 321–51. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-3531-0_11.

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Artikis, Panagiotis T., and Constantinos T. Artikis. "Consideration in Modeling of Random Contractions." In Learning and Analytics in Intelligent Systems, 27–104. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95691-2_2.

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Artikis, Panagiotis T., and Constantinos T. Artikis. "Formulations and Investigations of Random Contractions." In Learning and Analytics in Intelligent Systems, 105–87. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95691-2_3.

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Conference papers on the topic "Contractional system"

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Beddingfield, Chloe, Richard Cartwright, Richard Cartwright, Kelsey Crane, Kelsey Crane, Christian Klimczak, and Christian Klimczak. "POLYGONAL IMPACT CRATERS ON MERCURY’S LOBATE SCARPS: IMPLICATIONS FOR CONTRACTIONAL TECTONISM THROUGHOUT THE SOLAR SYSTEM." In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-377737.

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Chaves, Juliana N., Hani C. Yehia, and Henrique R. Martins. "Development of a portable labor-contraction monitor based on mechanomyography." In Simpósio Brasileiro de Computação Aplicada à Saúde. Sociedade Brasileira de Computação (SBC), 2022. http://dx.doi.org/10.5753/sbcas_estendido.2022.222422.

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Mechanomyography is a technique that measures the mechanical signal observed from the muscle surface during the contraction. It is expected to be a promising tool to evaluate uterine dynamics even though the uterus contraction is known to be involuntary. This study aimed to describe the development of a portable device based on mechanomyography to monitor uterine contraction. To assess the system was performed isometric contractions of the rectus femoris muscle with varying loads. The acquired data showed that the system could identify each contraction's onset, offset, and amplitude. The sensors and the system architecture proved to be a promising tool for the desired application.
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Reis, Maurício D. L., Eduardo Fermé, and Pavlos Peppas. "Construction of System of Spheres-based Transitively Relational Partial Meet Multiple Contractions: An Impossibility Result (Extended Abstract)." In Twenty-Sixth International Joint Conference on Artificial Intelligence. California: International Joint Conferences on Artificial Intelligence Organization, 2017. http://dx.doi.org/10.24963/ijcai.2017/719.

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In this paper we show that, contrary to what is the case in what concerns contractions by a single sentence, there is not a system of spheres-based construction of multiple contractions which generates each and every transitively relational partial meet multiple contraction. Furthermore, we propose two system of spheres-based constructions of multiple contractions which generate (only) transitively relational partial meet multiple contractions.
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Nohmi, Motohiko, Shusaku Kagawa, Tomoki Tsuneda, Wakana Tsuru, and Kazuhiko Yokota. "Numerical Analysis of Contraction Geometry Effects on Cavitation Choking in a Piping System." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5359.

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Abstract There is a contraction portion in the water supply pipe line system, and cavitation may occur in the contraction when the flow velocity is increased. Such a situation occurs widely in the throat of the fluid machineries and in the vicinity of the valve body of the valve. In operation of the valve, it is well known that a phenomenon occurs in which the flow rate does not increase even if the static pressure difference upstream and downstream of the valve is increased due to the growth of cavitation in the contraction, which is well known as choking . It is not clear what phenomena occurs when cavitation surge occurs in the pipe system in the situation where choking is occurring in the contraction. In this study, cavitation CFD was performed on pipes those have three different geometry contractions. It was revealed that choking occurred when cavitation occurred in any shape. Also, in the case with the sharp contraction part and the sudden expansion, the flow fluctuation at the upstream of the contraction is much weaker than that at the downstream, but in the contraction with the bent part where the centrifugal force acts on the flow, the flow fluctuation at the upstream was found to be strong.
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Ibrahim, B. S. K. K., M. O. Tokhi, S. C. Gharooni, and M. S. Huq. "Development of fuzzy muscle contraction and activation model using multi-objective optimisation." In 2010 4th Annual IEEE Systems Conference. IEEE, 2010. http://dx.doi.org/10.1109/systems.2010.5482462.

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Aboelkassem, Yasser, Anne E. Staples, and John J. Socha. "Microscale Flow Pumping Inspired by Rhythmic Tracheal Compressions in Insects." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57061.

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Inspired by the physiological network of insects, which have dimensions on the order of micrometers to millimeters, we study the airflow within a single model insect tracheal tube. The tube undergoes localized rhythmic wall contractions. A theoretical analysis is given to model the airflow within the tracheal tube. Since flow motions at the microscale are dominated mainly by viscous effects, and the tube has radius, R, that is much smaller than its length, L, (i.e. δ = R/L ≪ 1), lubrication theory for axisymmetric, viscous, incompressible flows at low Reynolds number (Re ∼ δ) is used to model the problem mathematically. Expressions for the velocity field, pressure gradient, wall shear stress and net flow produced by the driving tube wall contractions are derived. The effect of the contraction amplitudes, time lag, and spacing between two sequences of contractions on the time-averaged net flow over a single cycle of wall motions is investigated. The study presents a new, insect-inspired mechanism for valveless pumping that can guide efforts to fabricate novel microfluidic devices that mimic these physiological systems. A x-ray image that shows the tracheal network of the respiratory system of an insect (Carabid beetle) and the associated locations of these rhythmic contractions are shown in figure (1) to promote this study.
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Gulati, Shelly, Susan J. Muller, and Dorian Liepmann. "Direct Measurements of Viscoelastic Flows in Micro-Contractions." In ASME 3rd International Conference on Microchannels and Minichannels. ASMEDC, 2005. http://dx.doi.org/10.1115/icmm2005-75204.

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Direct measurement techniques are employed to quantify the kinematics of DNA flows in micro-contraction devices. Flow through micro-contractions subjects the fluid to large spatial gradients in velocity, thereby eliciting viscoelastic effects. Additionally, in this microfluidic flow environment, the fully extended length of the macromolecule L will approach the characteristic length scale of the channel geometry h. This is a unique flow environment that is not yet well understood. Knowledge of the fundamental physics that govern this flow regime will have a profound impact on optimization of lab-on-a-chip systems incorporating macromolecular flows. This study investigates the flow of semi-dilute λ-DNA solutions in a 2:1 micro-contraction where L/h ∼ 0.32. Video microscopy and streak images of semi-dilute DNA flows reveal large vortex regions in the corners of the contraction, which are indicative of strong elastic behavior. Velocity fields constructed using Digital Particle Image Velocimetry (DPIV) demonstrate the first use of this tool for obtaining velocity measurements of viscoelastic flows in microfluidic systems.
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Eschen, Kevin, and Julianna Abel. "Effect of Geometric Design Parameters on Contractile SMA Knitted Actuator Performance." In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3926.

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Shape memory alloy (SMA) knitted actuators are a type of functional fabric that uses shape memory alloy wire as an active fiber within a knitted textile. Through intentional design of the SMA knitted actuator geometry, various two- and three-dimensional actuation motions, such as scrolling and contraction [1], can be accomplished. Contractile SMA knitted actuators leverage the unique thermo-mechanical properties of SMA wires by integrating them within the hierarchical knitted structure to achieve large distributed uniaxial contractions and variable stiffness behavior upon thermal actuation. During the knit manufacturing process, the SMA wire is bent into a network of interlacing adjacent loops, storing potential energy within the contractile SMA knitted actuator. Thermal actuation above the wire-specific austenite finish temperature leads to a partial recovery of the bending deformations, resulting in large distributed uniaxial contraction (15–40% actuation contraction observed) of the SMA knitted actuator. The achievable load capacity and %-actuation contraction are dependent on the geometric loop parameters of the contractile SMA knitted actuator. While exact descriptions of the geometric loop parameters exist, a reduction of the geometric complexity is advantageous for high-level contractile SMA knitted actuator design procedures. This paper defines a simple geometric measure, the non-dimensional knit density, and experimentally correlates the contractile SMA knitted actuator performance to this measure. The experimentally demonstrated dependency of relevant actuator metrics on the knit density and the wire diameter, suggests the usability of the simplified geometry definition for a high-level contractile SMA knitted actuator design.
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Gustafson, Kenneth J., and Steven H. Reichenbach. "In Situ Thermal Measurements for Estimaton of Relative Metabolic Utilization in Skeletal Muscle." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0181.

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Abstract A variety of systems to drive cardiac assist devices with power from skeletal muscle have been proposed and are under development. The power available from a fixed mass of muscle is metabolically limited and maximizing sustained power is required for the successful application of such devices. The purpose of this study is to develop an approach that can yield relative metabolic utilization measures from single contractions of whole muscle used for cardiac assistance. Similar to classical muscle energetic studies, myothermic methods were employed in which muscle temperature was measured with a fast responding thermister and an infrared radiation thremopile transducer. In a series of tests on rabbit soleus muscle, the relative temperature increases during contractions were recorded. Relative muscle temperature increase was linearly related to the contraction duration. This relationship was incorporated into an existing muscle model to predict the optimum parameters for sustained skeletal muscle power generation.
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Nguyen, Lam, John Elsnab, and Tim Ameel. "Contraction/Expansion Effects in 90° Miter Bends in Rectangular Xurographic Microchannels." In ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2011. http://dx.doi.org/10.1115/icnmm2011-58148.

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Xurography is an inexpensive rapid prototyping technology for the development of microfluidic systems. Imprecision in the xurographic tape cutting process can result in undesired changes in channel dimensions near features that require a change in cutting direction, such as 90° miter bends. An experimental study of water flow in rectangular xurographic microchannels incorporating 90° miter bends with different channel widths in each leg is reported. A set of twelve microchannels, with channel depth approximately 105 micrometers and aspect ratio ranging from 0.071 to 0.435, were fabricated from double-sided adhesive Kapton® polyimide tape and two rectangular glass plates. The channels were reinforced with a mechanical clamping system, enabling high Reynolds number, Re, flows (up to Re = 3200) where Re was based upon hydraulic diameter and average velocity. Reported data include friction factor and critical Reynolds number for straight microchannels and loss coefficients for flow through 90° miter bends that contain either a contraction or expansion with cross-sectional area ratios of 0.5, 0.333 and 0.2. The critical Reynolds number, Recr, ranged from 1750 to 2300 and was found to be dependent on channel defects such as sidewall roughness, adhesive droplets, and corner imperfections. Loss coefficients through 90° miter bends with expansion decrease rapidly for Re < Recr. At the transition, the loss coefficient suddenly drops and approaches an asymptotic value for Re > Recr. For 90° miter bends with contractions, loss coefficients gradually decrease with increasing Re for 150 < Re < 1400. In addition, the loss coefficient decreases with decreasing area ratio through the contraction or expansion. The minor loss coefficient data were found to be dependent on Reynolds numbers and area ratio of contraction/expansion at the bend. The results suggest that the effect of the contraction/expansion was the dominant mechanism for minor losses in the 90° miter bend.
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Reports on the topic "Contractional system"

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Kahle, Kathleen, and René Stulz. Financial Policies and the Financial Crisis: How Important Was the Systemic Credit Contraction for Industrial Corporations? Cambridge, MA: National Bureau of Economic Research, August 2010. http://dx.doi.org/10.3386/w16310.

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Jalil, Yorschua, and Ruvistay Gutierrez. Myokines secretion and their role in critically ill patients. A scoping review protocol. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, September 2021. http://dx.doi.org/10.37766/inplasy2021.9.0048.

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Review question / Objective: 1-How and by which means stimulated muscle from critically ill patients can liberate myokines?, 2-Which are the main characteristics of the critically ill population studied and if some of these influenced myokine´s secretion?, 5-Can myokines exert local or distant effects in critically ill patients?, 5-Which are the potential effects of myokines in critically ill patients? Eligibility criteria: Participants and context: We will include primary studies (randomized or non-randomized trials, observational studies, case series or case report) that consider hospitalized critically ill adult patients (18 years or older) in risk for developing some degree of neuromuscular disorders such as ICU-AW, diaphragmatic dysfunction, or muscle weakness, therefore the specific setting will be critical care. Concept: This review will be focused on studies regarding the secretion or measure of myokines or similar (exerkines, cytokines or interleukin) by any mean of muscle activation or muscle contraction such as physical activity, exercise or NMES, among others. The latter strategies must be understood as any mean by which muscle, and there for myocytes, are stimulated as result of muscle contraction, regardless of the frequency, intensity, time of application and muscle to be stimulated (upper limb, lower limb, thoracic or abdominal muscles). We also will consider myokine´s effects, local or systemic, over different tissues in terms of their structure or function, such as myocytes function, skeletal muscle mass and strength, degree of muscle wasting or myopathies, among others.
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DeSantis, John, and Jeffery Roesler. Longitudinal Cracking Investigation on I-72 Experimental Unbonded Concrete Overlay. Illinois Center for Transportation, February 2022. http://dx.doi.org/10.36501/0197-9191/22-002.

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A research study investigated longitudinal cracking developing along an experimental unbonded concrete overlay (UBOL) on I-72 near Riverton, Illinois. The project evaluated existing literature on UBOL (design, construction, and performance), UBOL case studies, and mechanistic-empirical design procedures for defining the mechanisms that are contributing to the observed distresses. Detailed distress surveys and coring were conducted to assess the extent of the longitudinal cracking and faulting along the longitudinal lane-shoulder joint. Coring over the transverse contraction joints in the driving lane showed stripping and erosion of the dense-graded hot-mix asphalt (HMA) interlayer was the primary mechanism initiating the longitudinal cracks. Cores from the lane-shoulder joint confirmed stripping and erosion was also occurring there and leading to the elevation difference between the driving lane and shoulder. Field sections by surrounding state departments of transportation (DOTs), such as Iowa, Michigan, Minnesota, Missouri, and Pennsylvania, with similar UBOL design features to the I-72 section were examined. Site visits were performed in Illinois, Michigan, Minnesota, and Pennsylvania, while other sections were reviewed via state DOT contacts as well as Google Earth and Maps. Evidence from other DOTs suggested that HMA interlayers, whether dense graded or drainable, could experience stripping, erosion, and instability under certain conditions. An existing performance test for interlayers, i.e., Hamburg wheel-tracking device, and current models reviewed were not able to predict the distresses on I-72 eastbound. Adapting a dynamic cylinder test is a next step to screen HMA interlayers (or other stabilized layers) for stripping and erosion potential. To slow down the cracking and faulting on I-72 eastbound, sealing of the longitudinal lane-shoulder joint and driving lane transverse joints is suggested. To maximize UBOL service life, an HMA overlay will minimize water infiltration into the interlayer system and significantly slow down the HMA stripping and erosion mechanism that has led to longitudinal cracking and lane-shoulder faulting.
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Ruiz, Susana. ¿Quién paga la cuenta? Gravar la riqueza para enfrentar la crisis de la COVID-19 en América Latina y el Caribe. Oxfam, July 2020. http://dx.doi.org/10.21201/2020.6317.

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Las previsiones de retroceso económico y social en América Latina y el Caribe son alarmantes. La COVID-19 golpea con fuerza la región marcada que tendrá que afrontar una contracción del 9,4%, una de las más severas en todo el planeta. La desigualdad, la informalidad y la insuficiente dotación sanitaria lastran las posibilidades de hacer frente a la pandemia. Pero son los más vulnerables quienes asumen el costo, hasta 52 millones de personas que podrían caer en la pobreza y 40 millones podrían perder sus empleos, un retroceso de 15 años para la región. Pero la COVID-19 no afecta a todos por igual, una élite se mantiene inmune al contagio de la crisis económica. Desde el principio de los confinamientos, hay 8 nuevos milmillonarios en América Latina y el Caribe, personas con un patrimonio superior a los mil millones de dólares. Las personas más ricas han aumentado su fortuna en US$ 48 200 millones desde marzo 2020, lo que equivale a un tercio del total de los paquetes de estímulo de todos los países de la región. Para hacer frente a esta crisis tan profunda, Oxfam propone una serie de reformas que recaigan sobre quienes más tienen y menos han sufrido la pandemia. Entre otros un impuesto sobre el patrimonio neto de las personas más ricas con el que se podría recaudar al menos US$ 14 260 millones, 50 veces más de lo que ahora se estaría recaudando sobre esta élite de grandes fortunas. In the context of the COVID-19 pandemic, forecasts for economic and social decline in Latin America and the Caribbean are alarming. The region will face a 9.4% contraction in its economy, among the most severe in the world. Coping with the pandemic is hindered by inequality, weak and insufficient social protection and limited public health capabilities. Up to 52 million people could fall into poverty and 40 million could lose their jobs – a 15-year setback for the region. Yet, an elite remains ‘immune’ to the contagion of the economic crisis. Since the beginning of the pandemic, there have been 8 new billionaires in LAC: 1 every 2 weeks since the lockdowns began. The richest people have increased their fortune by $48.2bn since March 2020, equivalent to a third of the total stimulus packages of all countries in the region. In this paper, Oxfam proposes a series of reforms targeting those who have being less affected by the pandemic. They include a net wealth tax that could potentially generate $14.3bn, 50 times more than billionaires in the region pay now in theory, under current tax systems.
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Financial Stability Report - Second Semester of 2020. Banco de la República de Colombia, March 2021. http://dx.doi.org/10.32468/rept-estab-fin.sem2.eng-2020.

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The Colombian financial system has not suffered major structural disruptions during these months of deep economic contraction and has continued to carry out its basic functions as usual, thus facilitating the economy's response to extreme conditions. This is the result of the soundness of financial institutions at the beginning of the crisis, which was reflected in high liquidity and capital adequacy indicators as well as in the timely response of various authorities. Banco de la República lowered its policy interest rates 250 points to 1.75%, the lowest level since the creation of the new independent bank in 1991, and provided ample temporary and permanent liquidity in both pesos and foreign currency. The Office of the Financial Superintendent of Colombia, in turn, adopted prudential measures to facilitate changes in the conditions for loans in effect and temporary rules for rating and loan-loss provisions. Finally, the national government expanded the transfers as well as the guaranteed credit programs for the economy. The supply of real credit (i.e. discounting inflation) in the economy is 4% higher today than it was 12 months ago with especially marked growth in the housing (5.6%) and commercial (4.7%) loan portfolios (2.3% in consumer and -0.1% in microloans), but there have been significant changes over time. During the first few months of the quarantine, firms increased their demands for liquidity sharply while consumers reduced theirs. Since then, the growth of credit to firms has tended to slow down, while consumer and housing credit has grown. The financial system has responded satisfactorily to the changes in the respective demands of each group or sector and loans may grow at high rates in 2021 if GDP grows at rates close to 4.6% as the technical staff at the Bank expects; but the forecasts are highly uncertain. After the strict quarantine implemented by authorities in Colombia, the turmoil seen in March and early April, which was evident in the sudden reddening of macroeconomic variables on the risk heatmap in Graph A,[1] and the drop in crude oil and coal prices (note the high volatility registered in market risk for the region on Graph A) the local financial markets stabilized relatively quickly. Banco de la República’s credible and sustained policy response played a decisive role in this stabilization in terms of liquidity provision through a sharp expansion of repo operations (and changes in amounts, terms, counterparties, and eligible instruments), the purchases of public and private debt, and the reduction in bank reserve requirements. In this respect, there is now abundant aggregate liquidity and significant improvements in the liquidity position of investment funds. In this context, the main vulnerability factor for financial stability in the short term is still the high degree of uncertainty surrounding loan quality. First, the future trajectory of the number of people infected and deceased by the virus and the possible need for additional health measures is uncertain. For that reason, there is also uncertainty about the path for economic recovery in the short and medium term. Second, the degree to which the current shock will be reflected in loan quality once the risk materializes in banks’ financial statements is uncertain. For the time being, the credit risk heatmap (Graph B) indicates that non-performing and risky loans have not shown major deterioration, but past experience indicates that periods of sharp economic slowdown eventually tend to coincide with rises in non-performing loans: the calculations included in this report suggest that the impact of the recession on credit quality could be significant in the short term. This is particularly worrying since the profitability of credit establishments has been declining in recent months, and this could affect their ability to provide credit to the real sector of the economy. In order to adopt a forward-looking approach to this vulnerability, this Report presents several stress tests that evaluate the resilience of the liquidity and capital adequacy of credit institutions and investment funds in the event of a hypothetical scenario that seeks to simulate an extreme version of current macroeconomic conditions. The results suggest that even though there could be strong impacts on the credit institutions’ volume of credit and profitability under such scenarios, aggregate indicators of total and core capital adequacy will probably remain at levels that are above the regulatory limits over the horizon of a year. At the same time, the exercises highlight the high capacity of the system's liquidity to face adverse scenarios. In compliance with its constitutional objectives and in coordination with the financial system's security network, Banco de la República will continue to closely monitor the outlook for financial stability at this juncture and will make the decisions that are necessary to ensure the proper functioning of the economy, facilitate the flow of sufficient credit and liquidity resources, and further the smooth operation of the payment systems. Juan José Echavarría Governor
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