Transport efficiency and dynamics of hydraulic fracture networks

Acknowledgments This study is carried out within the framework of DGMK (German Society for Petroleum and Coal Science and Technology) research project 718 “Mineral Vein Dynamics Modeling,” which is funded by the companies ExxonMobil Production Deutschland GmbH, GDF SUEZ E&P Deutschland GmbH, RWE Dea AG and Wintershall Holding GmbH, within the basic research programme of the WEG Wirtschaftsverband Erdöl- und Erdgasgewinnung e.V. We thank the companies for their financial support and their permission to publish our results. We further acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of University of Tübingen.Peer reviewedPublisher PD

High-Fidelity Wing Design Exploration with Gradient-Based Optimization

Numerical optimization has been applied to wing design problems for over 40 years. Over the decades, the scope and detail of optimization problems have advanced considerably. At the present time, the state-of-the-art in wing design optimization incorporates high-fidelity modeling of the steady-state aeroelastic response of the wing at both on-design and off-design operating conditions. Reynolds-averaged solutions of the Navier–Stokes equations coupled with linear finite element anal- ysis offer the highest fidelity modeling currently tenable in an optimization con- text. However, the complexity of implementing and cost of executing high-fidelity aerostructural optimization have limited the extent of research on the topic. The goal of this dissertation is to examine the general application of these tools to wing design problems and highlight several factors pertaining to their usefulness and versatility. Two types of wing design problems are considered in this dissertation: refin- ing and exploratory. Refining problems are more common in practice, especially for high-fidelity optimization, because they start from a good design and make small changes to improve it. Exploratory problems are intended to have liberal parametrizations predisposed to have significant differences between the original and final designs. The investigation of exploratory problems yields novel findings regarding multimodality in the design space and robustness of the framework. Multimodality in the design space can impact the usefulness and versatility of gradient-based optimization in wing design. Both aerodynamic and aerostructural wing design problems are shown to be amenable to gradient-based optimization despite the existence of multimodality in some cases. For example, a rectangular wing with constant cross-section is successfully converted, through gradient-based optimization, into a swept-back wing with transonic airfoils and a minimum-mass structure. These studies introduce new insights into the tradeoff between skin- friction and induced drag and its impact on multimodality and optimization. The results of these studies indicate that multimodality is dependent on model fidelity and geometric parametrization. It is shown that artificial multimodality can be eliminated by improving model fidelity and numerical accuracy of functions and derivatives, whereas physically significant multimodality can be controlled with the application of geometric constraints. The usefulness of numerical optimization in wing design hinges on the ability of the optimizer to competently balance fundamental tradeoffs. With comprehensive access to the relevant design parameters and physics models of the aerostructural system, an optimizer can converge to a better multidisciplinary design than is pos- sible with a traditional, sequential design process. This dissertation features the high-fidelity aerostructural optimization of an Embraer regional jet, in which si- multaneous optimization of airfoil shape, planform, and structural sizing variables yields a significantly improved wing over the baseline design. For a regional jet, it is shown that the inclusion of climb and descent segments in the fuel burn com- putation has a significant impact on the tradeoff between structural weight and aspect ratio. Another study addresses the tradeoff between cruise performance and low-speed, high-lift flight characteristics. A separation constraint at a low-speed, high-lift condition is introduced as an effective method of preserving low-speed performance while still achieving significant fuel burn reduction in cruise.PHDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163242/1/nbons_1.pd

Where is God when dementia sneaks into our house? Practical theology and the partners of dementia patients

How can hope, love and faith stay alive when dementia enters a home? In this article I shall look especially at the spouse or partner who shares an abode with a person with dementia. Most of the authors in this field, also John Swinton who is perhaps the best known author whose books are written from a (practical) theological perspective, focus on care in institutions, that means care by professionals. A partner living with a dementia patient has two main roles: as partner and caregiver. Night and day a partner is witness to the ongoing deterioration of her or his beloved partner, without being a professional. This article is founded not only on literature about dementia patients, but also on the experiences of several partners, as well as my own experiences as a partner. The question we all ask is: ‘From where does our strength come?’ I argue that what is said in the literature on the subject of (the pastoral care for) dementia patients does not help the partners, because it lays a heavy burden on them, who are already suffering from feelings of grief and guilt. I do not agree with John Swinton’s idea that God created dementia. Looking for different ways of thinking about God and faith to survive with hope and love, I turn to the exegesis of the creation stories by Ellen van Wolde. These give the opportunity to take the evil of the situation of the deterioration of the personality of a patient with dementia seriously, and at the same time grant the possibility to turn the grief and guilt feelings into strength to fight evil, together with a God whose empathy and love stays with a partner in her or his loneliness and grief

Thoracic Aortic Disease: Imaging and Clinical Aspects

In this thesis we answer the question how the thoracic aorta can be measured most reliably with imaging techniques. In addition, the thoracic aorta is studied in the general population and the effect of some specific diseases, pregnancy and sports on the thoracic aorta is described

A place to share: Some thoughts about the meaning of territory and boundaries in our thinking about God and humanity

This article proffers some thoughts in reply to the following question: how can we think about God in a theology that takes into account the concept of place in such a way that we are able to live together in a salvific way with others, sharing a place as equals? Concepts such as “territory” and “territoriality” are helpful, because they can be linked with “identity” and the need to feel safe. Boundaries and boundary markers such as walls play an important role in conflicts. The possibility of a “liminal space” at a boundary where eye-to-eye relationships may be possible helps to make “the other”, the stranger, a human being with her/his own needs and vulnerability. Using the Israeli/Palestinian conflict as an example, images of God and their impact on the possibility of sharing the land are explored. Hagar, herself a stranger, experiences God\'s lifesaving attention and names God “God of seeing”. HTS Theological Studies Vol. 64 (1) 2008: pp. 141-15

Micro-dynamics of ice

No abstract available

Mulching: A viable option to increase productivity of field and fruit crops

Mulching plays an important role in production of agricultural and horticultural crops in the current scenario of declining water table, soil degradation and climate change. The main objectives of mulching are to prevent loss of water by evaporation, prevention of soil erosion, weed control, to reduce fertilizer leaching, to promote soil productivity, to enhance yield and quality of field and fruit crops. So, mulching is useful to save our underground water resource, soil and environment for sustainable crop production. In this review paper, the literature clearly shows pronounced effects of mulching on soil health by improving the soil structure, soil fertility, biological activities, avoid soil degradation in addition to moisture conservation, regulating temperature, encouraging change in favourable micro-climate, check weed growth and ultimately increasing the productivity, quality, profitability and sustainability of crops and cropping systems irrespective of the system/situation

A new stylolite classification scheme to estimate compaction and local permeability variations

This study was carried out within the framework of DGMK (German Society for Petroleum and Coal Science and Technology) research project 718 “Mineral Vein Dynamics Modeling”, which is funded by the companies ExxonMobil Production Deutschland GmbH, GDF SUEZ E&P Deutschland GmbH, DEA Deutsche Erdoel AG and Wintershall Holding GmbH, within the basic research program of the WEG Wirtschaftsverband Erdoel- und Erdgasgewinnung e.V. We thank the companies for their financial support and their permission to publish these results. This work has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 31688. The Zechstein data were collected with the help of Simon Gast. We thank Jean-Pierre Gratier and an anonymous reviewer for their comments that improved an earlier version of the manuscript.Peer reviewedPostprin