10,851 research outputs found
Fabrication of Hollow AlAu2 Nanoparticles by Solid State Dewetting and Oxidation of Al on Sapphire Substrate
The Al-Au binary diffusion couple is a classic example of the system
exhibiting Kirkendall voiding during interdiffusion. We demonstrate that this
effect, which is a major reason for failures of the wire bonds in
microelectronics, can be utilized for producing hollow AlAu2 nanoparticles
attached to sapphire substrate. To this end, we produced the core-shell Al-Au
nanoparticles by performing a solid state dewetting treatment of Al thin film
deposited on sapphire substrate, followed by the deposition of thin Au layer on
the top of dewetted sample. Annealing of the core-shell nanoparticles in air
resulted in outdiffusion of Al from the particles, formation of pores, and
growth of the AlAu2 intermetallic phase in the particles. We demonstrated that
the driving force for hollowing is the oxidation reaction of the Al atoms at
the Au-sapphire interface, leading to the homoepitaxial growth of newly formed
alumina at the interface. We developed a kinetic model of hollowing controlled
by diffusion of oxygen through the Au thin film, and estimated the solubility
of oxygen in solid Au. Our work demonstrates that the core-shell nanoparticles
attached to the substrate can be hollowed by the Kirkendall effect in the thin
film spatially separated from the particles.Comment: 27 pages, 8 figure
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In search of the hollow crown
The first volume in a series of comparative studies within the ESRC's Whitehall Programme focuses on core executives in five parliamentary democracies comparing the Westminster model as in Australia, Canada and Britain with the continental democracies of Germany and the Netherlands showing how political leadership is shackled by a vast array of constraints, from globalisation to internal fragmentation and rationalisation, making a heroic model of decisive political leadership hard to sustain
Static and dynamic properties of shell-shaped condensates
Static, dynamic, and topological properties of hollow systems differ from
those that are fully filled as a result of the presence of a boundary
associated with an inner surface. Hollow Bose-Einstein condensates (BECs)
naturally occur in various ultracold atomic systems and possibly within neutron
stars but have hitherto not been experimentally realized in isolation on Earth
because of gravitational sag. Motivated by the expected first realization of
fully closed BEC shells in the microgravity conditions of the Cold Atomic
Laboratory aboard the International Space Station, we present a comprehensive
study of spherically symmetric hollow BECs as well as the hollowing transition
from a filled sphere BEC into a thin shell through central density depletion.
We employ complementary analytic and numerical techniques in order to study
equilibrium density profiles and the collective mode structures of condensate
shells hosted by a range of trapping potentials. We identify concrete and
robust signatures of the evolution from filled to hollow structures and the
effects of the emergence of an inner boundary, inclusive of a dip in
breathing-mode-type collective mode frequencies and a restructuring of surface
mode structure across the transition. By extending our analysis to a
two-dimensional transition of a disk to a ring, we show that the collective
mode signatures are an essential feature of hollowing, independent of the
specific geometry. Finally, we relate our work to past and ongoing experimental
efforts and consider the influence of gravity on thin condensate shells. We
identify the conditions under which gravitational sag is highly destructive and
study the mode-mixing effects of microgravity on the collective modes of these
shells.Comment: 26 pages, 13 figure
The Japanese model in retrospective : industrial strategies, corporate Japan and the 'hollowing out' of Japanese industry
This article provides a retrospective look at the Japanese model of industrial development. This model combined an institutional approach to production based around the Japanese Firm (Aoki's, J-mode) and strategic state intervention in industry by the Japanese Ministry of International Trade and Industry (MITI). For a long period, the alignment of state and corporate interests appeared to match the wider public interest as the Japanese economy prospered. However, since the early 1990s, the global ambitions of the corporate sector have contributed to a significant 'hollowing out' of Japan's industrial base. As the world today looks for a new direction in economic management, we suggest the Japanese model provides policy-makers with a salutary lesson in tying the wider public interest with those of the corporate sector
Changes in Manufacturing Linkage Patterns in Scotland and Wales: Hollowing Out and Foreign Direct Investment?
Trends in inward investment in Scotland and Wales have influenced manufacturingâs inter-linkages with the local economy in different ways. The paper shows that there could be a hollowing out of the manufacturing sector in these regional economies which is linked to trends in inward investment.
THE PROBLEM OF REGIONAL "HOLLOWING OUT" IN JAPAN : LESSONS FOR REGIONAL INDUSTRIAL POLICY
This paper considers the problems of "hollowing out" using a Case Study of Japan's machinery sector. In doing so, it explores the roots of the present crisis by focusing upon the role played by Japan's large transnational corporations. This is important because these corporations are the "central actors" within the Japanese economy and they control a significant proportion of Japanese manufacturing. It is their strategic decisions - those that determine the level and location of investment, employment and output - which ultimately shape the development path for Japanese industry (see Cowling and Sugden, 1994, 1998). In recent years, Japanâs large transnationals have become engaged in the process of elite globalisation, pursuing their own interests at the expense of domestic Japanese industry. This is a fundamental insight that is crucial for designing appropriate policy responses to arrest Japan's current industrial decline. It is argued that the lessons from Japan's experience might guide policymakers in other regions, such as Wisconsin, who are concerned with future industrial development, the effects of globalisation and problems of "hollowing out".Machinery sector ; strategic-decision making ; strategic failure ; industrial policy.
From 3D Models to 3D Prints: an Overview of the Processing Pipeline
Due to the wide diffusion of 3D printing technologies, geometric algorithms
for Additive Manufacturing are being invented at an impressive speed. Each
single step, in particular along the Process Planning pipeline, can now count
on dozens of methods that prepare the 3D model for fabrication, while analysing
and optimizing geometry and machine instructions for various objectives. This
report provides a classification of this huge state of the art, and elicits the
relation between each single algorithm and a list of desirable objectives
during Process Planning. The objectives themselves are listed and discussed,
along with possible needs for tradeoffs. Additive Manufacturing technologies
are broadly categorized to explicitly relate classes of devices and supported
features. Finally, this report offers an analysis of the state of the art while
discussing open and challenging problems from both an academic and an
industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and
Innovation action; Grant agreement N. 68044
Enhancing Robustness and Immunization in geographical networks
We find that different geographical structures of networks lead to varied
percolation thresholds, although these networks may have similar abstract
topological structures. Thus, the strategies for enhancing robustness and
immunization of a geographical network are proposed. Using the generating
function formalism, we obtain the explicit form of the percolation threshold
for networks containing arbitrary order cycles. For 3-cycles, the
dependence of on the clustering coefficients is ascertained. The analysis
substantiates the validity of the strategies with an analytical evidence.Comment: 6 pages, 8 figure
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