4,231 research outputs found
In-situ growth optimization in focused electron-beam induced deposition
We present the application of an evolutionary genetic algorithm for the
in-situ optimization of nanostructures prepared by focused
electron-beam-induced deposition. It allows us to tune the properties of the
deposits towards highest conductivity by using the time gradient of the
measured in-situ rate of change of conductance as fitness parameter for the
algorithm. The effectiveness of the procedure is presented for the precursor
W(CO)6 as well as for post-treatment of Pt-C deposits obtained by dissociation
of MeCpPt(Me)3. For W(CO)6-based structures an increase of conductivity by one
order of magnitude can be achieved, whereas the effect for MeCpPt(Me)3 is
largely suppressed. The presented technique can be applied to all beam-induced
deposition processes and has great potential for further optimization or tuning
of parameters for nanostrucures prepared by FEBID or related techniques
Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced deposition
Fe-Si binary compounds have been fabricated by focused electron beam induced
deposition by the alternating use of iron pentacarbonyl, Fe(CO)5, and
neopentasilane, Si5H12 as precursor gases. The fabrication procedure consisted
in preparing multilayer structures which were treated by low-energy electron
irradiation and annealing to induce atomic species intermixing. In this way we
are able to fabricate FeSi and Fe3Si binary compounds from [Fe=Si]2 and
[Fe3=Si]2 multilayers, as shown by transmission electron microscopy
investigations. This fabrication procedure is useful to obtain nanostructured
binary alloys from precursors which compete for adsorption sites during growth
and, therefore, cannot be used simultaneously
Factorization for generic jet production
Factorization is the central ingredient in any theoretical prediction for
collider experiments. We introduce a factorization formalism that can be
applied to any desired observable, like event shapes or jet observables, for
any number of jets and a wide range of jet algorithms in leptonic or hadronic
collisions. This is achieved by using soft-collinear effective theory to prove
the formal factorization of a generic fully-differential cross section in terms
of a hard coefficient, and generic jet and soft functions. In this formalism,
whether a given observable factorizes in the usual sense, depends on whether it
is inclusive enough, so the jet functions can be calculated perturbatively. The
factorization formula for any such observable immediately follows from our
general result, including the precise definition of the jet and soft functions
appropriate for the observable in question. As examples of our formalism, we
work out several results in two-jet production for both e+e- and pp collisions.
For the latter, we also comment on how our formalism allows one to treat
underlying events and beam remnants.Comment: 33 pages, v2: minor typos corrected, journal versio
Fatal attractors in parity games
We study a new form of attractor in parity games and use it to define solvers that run in PTIME and are partial in that they do not solve all games completely. Technically, for color c this new attractor determines whether player c%2 can reach a set of nodes X of color c whilst avoiding any nodes of color less than c. Such an attractor is fatal if player c%2 can attract all nodes in X back to X in this manner. Our partial solvers detect fixed-points of nodes based on fatal attractors and correctly classify such nodes as won by player c%2. Experimental results show that our partial solvers completely solve benchmarks that were constructed to challenge existing full solvers. Our partial solvers also have encouraging run times. For one partial solver we prove that its runtime is in O(|V |3), that its output game is independent of the order in which attractors are computed, and that it solves all B¨uchi games
PCTL Model Checking of Markov Chains: Truth and Falsity as Winning Strategies in Games
Probabilistic model checking is a technique for verifying whether a model such as a Markov chain satisfies a probabilistic, behavioral property – e.g. “with probability at least 0.999, a device will be elected leader. ” Such properties are expressible in probabilistic temporal logics, e.g. PCTL, and efficient algorithms exist for checking whether these formulae are true or false on finite-state models. Alas, these algorithms don’t supply diagnostic information for why a probabilistic property does or does not hold in a given model. We provide here complete and rigorous foundations for such diagnostics in the setting of countable labeled Markov chains and PCTL. For each model and PCTL formula, we define a game between a Verifier and a Refuter that is won by Verifier if the formula holds in the model, and won by Refuter if it doesn’t hold. Games are won by exactly one player, through monotone strategies that encode the diagnostic information for truth and falsity (respectively). These games are infinite with Büchi type acceptance conditions where simpler fairness conditions are shown not be to sufficient. Verifier can always force finite plays for certain PCTL formulae, suggesting the existence of finite-state abstractions of models that satisfy such formulae
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Agile manufacturing: General challenges and an IoT@Work perspective
This paper describes the potential impact of the Internet of Things (IoT) technologies and architecture on factory automation. Whereas, IoT use cases range from intelligent infrastructure and smart cities to health care and shopping assistants, it is important to note that factory automation could benefit as well from an IoT approach. In this paper, we argue that there will not be one IoT but many IoTs that could differ in the type of infrastructure they are running or applications they support. In IoT@Work we focus on the potential of making manufacturing environments more agile and flexible. We explain how the IoT-centric architecture for manufacturing also needs a deep understanding of the manufacturing system and its state today. We, therefore, do a reverse engineering based on the requirements and the description of the agility expected in the automation system itself
Domain wall dynamics in a single CrO grain
Recently we have reported on the magnetization dynamics of a single CrO
grain studied by micro Hall magnetometry (P. Das \textit{et al.}, Appl. Phys.
Lett. \textbf{97} 042507, 2010). For the external magnetic field applied along
the grain's easy magnetization direction, the magnetization reversal takes
place through a series of Barkhausen jumps. Supported by micromagnetic
simulations, the ground state of the grain was found to correspond to a flux
closure configuration with a single cross-tie domain wall. Here, we report an
analysis of the Barkhausen jumps, which were observed in the hysteresis loops
for the external field applied along both the easy and hard magnetization
directions. We find that the magnetization reversal takes place through only a
few configuration paths in the free-energy landscape, pointing to a high purity
of the sample. The distinctly different statistics of the Barkhausen jumps for
the two field directions is discussed.Comment: JEMS Conference, to appear in J. Phys. Conf. Se
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