Preconditioned and Randomized Methods for Efficient Bayesian Inversion of Large Data Sets and their Application to Flow and Transport in Porous Media

The efficient and reliable estimation of model parameters is important for the simulation and optimization of physical processes. Most models contain variables that have to be adjusted, e.g. in the form of material properties, and the uncertainty of state estimates and predictions is directly linked to the uncertainty of these parameters. Therefore, efficient methods for parameter estimation and uncertainty quantification are required. If the physical system is spatially highly heterogeneous, then the number of model parameters can be very large. At the same time, imaging techniques and time series can provide a large number of measurements for model calibration. Many of the available methods become inefficient or outright unfeasible if both the number of model parameters and the number of state observations are large. This thesis is concerned with the development of methods that remain efficient when a large number of measurements is used to estimate an even larger number of model parameters. The main result is a special preconditioned Conjugate Gradients method that can achieve both quasilinear complexity in the number of parameters and pseudo-constant complexity in the number of measurements. The thesis also provides randomized methods that allow linearized uncertainty quantification for large systems, taking redundancy in the measurements into account if applicable

Precourse to the PeC3 Summer School on Introduction on Numerical Modelling with Differential Equations

Precourse to the PeC3 Summer School on Introduction on Numerical Modelling with Differential Equation

Structurally parametric identification of object descrete models with delay for tuning smith controllers

Construction of Smith digital controller on the basis of equivalence principle of dynamic object models with delay has been suggeste

«ДОФЕНОМЕНОЛОГІЧНА» КОНЦЕПЦІЯ БРЕНТАНО ЯК ТЛО ДЛЯ РОЗВИТКУФЕНОМЕНОЛОГІЇ ТА АКСІОЛОГІЇ ХІХ- ХХСТОЛІТТЯ

В представленном исследовании автор анализирует эмпирическую психологію Ф. Брентано, в частности, процесс конституированиянепосредственных данностей– внутреннее существование предмета. Такой подход стал новым акцентированием «эмпиричности» и попыткой возобновления связи между философией и психологией посредством понятия «интенциональность», которое является теоретико-познавательным принципом.In this investigation author analyses empirical psychology of F.Brentano –the procces of constitute spontaneous facts as inside existence the object. This idea have an influence development of the transcendental phenomenology, hermeneutical phenomenology and have be essential for development of the contemporary philosophy of the value

The role of Ca²⁺ and other ion channels in AVP-stimulated ACTH release from ovine anterior pituitary cells

The role and regulation of Ca²⁺ and other ion channels in the in vitro adrenocorticotropin (ACTH) response to arginine vasopressin (AVP), were investigated in static cultures of ovine anterior pituitary cells. Previous evidence suggests that the action of AVP in ACTH secreting (corticotroph) cells involves the activation of the polyphosphoinositide-derived (PI) second-messenger system, and has also been shown to be dependent on Ca²⁺ influx. In this report, a variety of chemically distinct blockers of Ca²⁺ influx, including the organic agents (methoxyverapamil (D600), nifedipine and diltiazem) and the inorganic ions (Cd²⁺ and Co²⁺) were all found to cause large reductions in the AVP-stimulated ACTH response, providing further evidence that the AVP-induced response is dependent on Ca²⁺ influx to a large degree. However, the entire AVP-induced response was not inhibited by the blockers, suggesting that other factors, such as release of intracellularly stored Ca²⁺ also participates in this response. The blocking agents used in this study are all classified as blockers of L-type (L-) voltage-sensitive Ca²⁺ channels (VSCC), and thus the results suggest that L-VSCC are responsible for the bulk of the Ca²⁺ influx that underlies the AVP-induced response. The inorganic blocking ions also inhibit T-type (T-) VSCC, and thus it is possible that these channels also contribute to the response. In cells that possess voltage-activated Ca²⁺ channels, raising the extracellular K⁺ concentration ([K⁺]e) typically evokes hormone secretion, due to depolarisation-induced Ca²⁺ influx via the voltage-sensitive channels. Raising [K⁺]e caused ACTH secretion from ovine corticotrophs, and this response was also sensitive to VSCC blockers. These results provide further support for the presence of VSCC in ovine corticotrophs. Simultaneous stimulation with AVP and raised [K⁺]e caused a level of ACTH secretion that was less than the sum of the individual responses, when the concentrations of the secretagogues were moderate to high. This result is consistent with the hypothesis that both secretagogues activate, to some extent, the same population of Ca²⁺ channels during their respective responses. At low concentrations of the secretagogues, a synergistic response was observed. Further experimentation and analysis suggested that this response may be generated at the level of Ca²⁺ influx, and thus raised the possibility that the VSCC may be subject to dual voltage and voltage-independent regulation. The possibility that voltage-independent regulation of VSCC activity by protein kinase C (PKC), part of the PI second-messenger system, occurred during the response to AVP was explored by down-regulating PKC activity. This was achieved by chronic exposure of pituitary cells to the PKC-activating phorbol ester, 12-0-tetradecanoylphorbol 13 -acetate (TPA). This treatment totally inactivated PKC, reduced the responses to AVP, but not K⁺e and abolished the synergistic interaction between AVP and K⁺e. Thus these results are consistent with a role for PKC in the AVP-induced ACTH response, and with the hypothesis that the synergistic response occurs due to voltage-independent (chemical) regulation of VSCC. This hypothesis was further supported by the finding that simultaneous stimulation with TPA plus raised [K⁺]e caused synergistic ACTH responses. The possibility that PKC activates VSCC was investigated by examining the effects of VSCC blockers on TPA-stimulated ACTH release. The organic blocker, D600, and the inorganic ion, Co²⁺, both reduced the TPA-induced response. However, the patterns of inhibition were not entirely consistent with those previously observed for inhibition of AVP-induced secretion. Thus an additional protocol, reducing or removing Ca²⁺ from the extracellular medium, was employed to investigate the involvement of Ca²⁺ influx during the response to TPA. This protocol reduced both AVP- and TPA-stimulated ACTH release, and thus provided additional evidence that the AVP-induced response is dependent on Ca²⁺ influx, and further suggested that PKC can activate Ca²⁺ influx in ovine corticotrophs. Thus the possibility that AVP-activated PKC can affect VSCC activity in corticotroph cells is a viable hypothesis. Voltage regulation of VSCC by AVP, and the effects on ACTH secretion, were also investigated. The possibility that AVP may create a depolarisation stimulus via PKC-mediated inhibition of a K⁺ current that is active at rest, was examined. Exposure of cells to the K⁺ channel blocker tetraethylammonium (TEA), stimulated a small increase in ACTH release that was sensitive to Ca²⁺ channel blockers. These findings are consistent with the hypothesis under investigation. Exposure of cells to TEA in the presence of AVP or TPA enhanced the responses to these secretagogues, suggesting that a (possibly Ca²⁺-activated) K⁺ current (distinct from the one discussed in the previous paragraph) is present in ovine corticotrophs, and may act to regulate the cellular response to these agents. Removal of external Na⁺ caused a small reduction in AVP-stimulated ACTH release, suggesting that Na+ channels may play a minor role in the response to AVP. These investigations extend the current knowledge regarding the regulation of the AVP-induced ACTH response, particularly with respect to ovine cells

Securitization and the construction of security

Those interested in the construction of security in contemporary international politics have increasingly turned to the conceptual framework of `securitization'. This article argues that while an important and innovative contribution, the securitization framework is problematically narrow in three senses. First, the form of act constructing security is defined narrowly, with the focus on the speech of dominant actors. Second, the context of the act is defined narrowly, with the focus only on the moment of intervention. Finally, the framework of securitization is narrow in the sense that the nature of the act is defined solely in terms of the designation of threats. In outlining this critique, the article points to possibilities for developing the framework further as well as for the need for those applying it to recognize both limits of their claims and the normative implications of their analysis. I conclude by pointing to how the framework might fit within a research agenda concerned with the broader construction of security

Estimation of contact resistivity in lightning protection equipotential Bonding joints of wind turbine blades

Modern lightning protection systems for wind turbine blades with conducting structural elements, e.g., carbon fiber reinforced polymer (CFRP) spar caps, contain equipotential bonding joints to prevent sparking during strikes. Significant current levels are experienced through the joints and the characterization of the electrical contact at the bonding regions is essential for reliable protection. Therefore, this article aims to characterize the contact resistivity of several equipotential bonding joints. The proposed methodology first measures the total resistance of the samples, and then the bulk resistance of the conductive elements is computed using the finite-element method. The latter is required to predict the spreading effects in CFRP components due to the strong anisotropic nature of such materials. After that, the contact resistance is calculated by subtracting the predicted bulk resistances from the measured total resistances. The developed procedure was applied to three typical equipotential bonding materials: expanded copper foil (ECF), biaxial (BIAX) CFRP, and unidirectional (UD) CFRP. Both ECF and BIAX CFRP showed superior contact quality than the UD CFRP, with one to two orders of magnitude smaller contact resistivity.</p