1,166 research outputs found
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The European Union and party politics in Central Europe
It is only recently that political scientists have begun to focus on the influence of European Union involvement on national parties. Mair's study of the impact of Europe on the parties of Western Europe is now a standard point of reference, and relatively little divergence can be seen from his view that the direct impact of EU involvement has been strictly limited. An extensive research project on the Europeanization of national party organizations has recently been completed and it, too, seems to have found little evidence that European-level decision-making has greatly changed the balance of power within national political parties. In the past few years, publications on Central Europe developments have also begun to appear. Empirical studies of the Europeanization of CE parties have, however, been less common than work on EU effects in related fields. We conclude here that in CE party politics the logic of national competition has overridden other logics, including that of the EU. But integration has still shaped party systems in various ways. Parties converge, though with significant exceptions, towards the classic European ideological patterns and are rapidly integrating with the European party federations. Coalition alternatives and policy options have generally been constrained by the integration process, but it is not possible to state generally whether the EU has affected the stability of CE party systems. Integration may well have increased the distance between elites and citizens and depoliticized certain issues but, in contrast to claims made of WE, we cannot really speak of a 'hollowing out' of party competition. Some organizational changes can be identified. The EU has had an impact on the internal norms of some parties as far as gender quotas are considered. But party organization as a whole has not greatly changed, although MEPs have often been given representation in the party leadership. The pervasiveness of EU impacts is nevertheless highly differentiated and far from unambiguous, leaving considerable scope for continuing variation in post-accession party politics in Central Europe
Control of Ocean Wave Energy Converters with Finite Stroke
In the design of ocean wave energy converters, proper control design is essential for the maximization of power generation performance. However, in practical applications, this control must be undertaken in the presence of stroke saturation and model uncertainty. In this dissertation, we address these challenges separately.
To address stroke saturation, a nonlinear control design procedure is proposed, which guarantees to keep the stroke within its limits. The technique exploits the passivity of the wave energy converter to guarantee closed-loop stability. The proposed technique consists of three steps: 1) design of a linear feedback controller using multi-objective optimization techniques; 2) augmentation of this design with an extra input channel that adheres to a closed-loop passivity condition; and 3) design of an outer, nonlinear passive feedback loop that controls this augmented input in such a way as to ensure stroke limits are maintained. The discrete-time version of this technique is also presented.
To address model uncertainty, in particular we consider the nonlinear viscosity drag effect as the model uncertainty. This robust control design problem can be regarded as a multi-objective optimization problem, whose primary objective is to optimize the nominal performance, while the second objective is to robustly stabilize the closed-loop system. The robust stability constraint can be posed using the concept of circle criterion. Because this optimization is non-convex, Loop Transfer Recovery methods are used to solve for sub-optimal solutions to the problem.
These techniques are demonstrated in simulation, for arrays of buoy-type wave energy converters.PHDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163263/1/waynelao_1.pd
A systematic approach to design for lifelong aircraft evolution
Modern aerospace systems rely heavily on legacy platforms and their derivatives. Historical examples show that after a vehicle design is frozen and delivered to a customer, successive upgrades are often made to fulfill changing requirements. Current practices of adapting to emerging needs with derivative designs, retrofits, and upgrades are often reactive and ad-hoc, resulting in performance and cost penalties. Recent DoD acquisition policies have addressed this problem by establishing a general paradigm for design for lifelong evolution. However, there is a need for a unified, practical design approach that considers the lifetime evolution of an aircraft concept by incorporating future requirements and technologies.
This research proposes a systematic approach with which the decision makers can evaluate the value and risk of a new aircraft development program, including potential derivative development opportunities. The proposed Evaluation of Lifelong Vehicle Evolution (EvoLVE) method is a two- or multi-stage representation of the aircraft design process that accommodates initial development phases as well as follow-on phases. One of the key elements of this method is the Stochastic Programming with Recourse (SPR) technique, which accounts for uncertainties associated with future requirements. The remedial approach of SPR in its two distinctive problem-solving steps is well suited to aircraft design problems where derivatives, retrofits, and upgrades have been used to fix designs that were once but no longer optimal. The solution approach of SPR is complemented by the Risk-Averse Strategy Selection (RASS) technique to gauge risk associated with vehicle evolution options. In the absence of a full description of the random space, a scenario-based approach captures the randomness with a few probable scenarios and reveals implications of different future events. Last, an interactive framework for decision-making support allows simultaneous navigation of the current and future design space with a greater degree of freedom. A cantilevered beam design problem was set up and solved using the SPR technique to showcase its application to an engineering design setting. The full EvoLVE method was conducted on a notional multi-role fighter based on the F/A-18 Hornet.Ph.D.Committee Chair: Mavris, Dimitri; Committee Member: Bishop, Carlee; Committee Member: Costello, Mark; Committee Member: Nam, Taewoo; Committee Member: Schrage, Danie
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Damage and repair identification in reinforced concrete beams modelled with various damage scenarios using vibration data
This research aims at developing a novel vibration-based damage identification technique that can efficiently be applied to real-time large data for detection, classification, localisation and quantification of the potential structural damage
The Optical Properties of Spiky Gold Nanoshells
Plasmonic nanoparticles are a powerful and versatile tool for molecular sensing, drug delivery, and cancer treatment. When exposed to incident light, these nanoparticles have greatly increased far-field scattering and near-field enhancement. Spiky gold nanoshells are a recently developed class of nanoparticles composed of sharp gold spikes decorating a polystyrene core. Spiky nanoshells are synthesized using the templated surfactant-assisted seed growth method, which enables extensive control of the nanoparticle morphology. Here, it is shown that these particles have a tailorable far-field resonance, extremely uniform single-particle surface enhanced Raman scattering, and modal interference in dark-field microscopy measurements. Finite-difference time-domain simulations are performed to determine the morphological features which control these unusual behaviors. Additionally, a T-matrix method was developed to use finite-difference time-domain simulations to analyze mode mixing in these particles. These studies show that the lengths of spikes are critical in determining the far-field scattering peak. Additionally, simulation of the electric field near the particle surface show that the near-field Raman surface enhancement is dominated by the quadrupole modes, resulting in Quadrupole Enhanced Raman Scattering. Due to the large number of spikes, the near-field enhancement is relatively insensitive to variations in individual spikes, resulting in emergent homogeneity in optical properties due to heterogeneity in the structure. The disorder induced asymmetry of the spiky nanoshell enables mode-mixing between the dipole and quadrupole modes, which is observed experimentally in dark-field measurements and predicted theoretically in a T-matrix analysis of finite-difference time-domain simulations. This mode mixing was found to be of the order of 5% between the quadrupole and dipole modes. Such mode mixing is responsible for the broadening of the quadrupole modes towards the infrared and for the activation of all six quadrupole moments, partially explaining how heterogeneity can result in reliable and robust near-field enhancement
Operationalizing the BIG Collective Collection: A Case Study of Consolidation vs Autonomy
This is a discussion paper prepared in collaboration with the Big Ten Academic Alliance (BTAA) Library Initiatives. It presents a framework for operationalizing the BTAA collective collection. A collective collection is a collection managed collaboratively across a network of libraries. We have a very specific focus in this paper on the ”purchased” or print collection, acknowledging that other areas of library collections are sometimes managed collectively, digitized collections for example. The BTAA justifiably claims to be the premier academic collaboration in the US. Once described as “the world\u27s greatest common market in education3,” it leverages the combined research and teaching capacity of major research universities to scale innovation, impact, and economies across its 14 members. Together, the BTAA members have a profound social and economic impact throughout a large part of the US. Libraries are a central part of the BTAA research, learning, and teaching endeavor. They collectively mobilize major expertise and resources. In fact, the BTAA collection represents more than a fifth of all titles in the North American print book collection. The BTAA libraries align with BTAA goals by collaborating at scale to increase both impact and efficiency.
The character of library spaces, services, and collections is evolving with changing learning and research behaviors. It is widely recognized that continued autonomous development of large standalone collections does not meet needs and is not efficient. A library cannot collect all that its members would like to see, and much of what it does collect does not get used. At the same time, library space is being configured around engagement rather than around collections, the long-term stewardship costs of print materials are being recognized, and the role of books in research and learning is changing. Libraries are re-evaluating traditional approaches to building, managing, and sharing collections, and are increasingly looking to do this cooperatively. In this paper, we define and explore key attributes of collective collections and present a series of recommendations designed to advance the BTAA libraries toward a more purposeful coordination of their collections. Doing all that we propose would involve an extensive multi-year program. The approach we recommend here is broadly applicable in other consortium settings as well, which is why we characterize the paper as a case study
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