8,312 research outputs found
Sufficient Conditions for Feasibility and Optimality of Real-Time Optimization Schemes - II. Implementation Issues
The idea of iterative process optimization based on collected output
measurements, or "real-time optimization" (RTO), has gained much prominence in
recent decades, with many RTO algorithms being proposed, researched, and
developed. While the essential goal of these schemes is to drive the process to
its true optimal conditions without violating any safety-critical, or "hard",
constraints, no generalized, unified approach for guaranteeing this behavior
exists. In this two-part paper, we propose an implementable set of conditions
that can enforce these properties for any RTO algorithm. This second part
examines the practical side of the sufficient conditions for feasibility and
optimality (SCFO) proposed in the first and focuses on how they may be enforced
in real application, where much of the knowledge required for the conceptual
SCFO is unavailable. Methods for improving convergence speed are also
considered.Comment: 56 pages, 15 figure
Sufficient Conditions for Feasibility and Optimality of Real-Time Optimization Schemes - I. Theoretical Foundations
The idea of iterative process optimization based on collected output
measurements, or "real-time optimization" (RTO), has gained much prominence in
recent decades, with many RTO algorithms being proposed, researched, and
developed. While the essential goal of these schemes is to drive the process to
its true optimal conditions without violating any safety-critical, or "hard",
constraints, no generalized, unified approach for guaranteeing this behavior
exists. In this two-part paper, we propose an implementable set of conditions
that can enforce these properties for any RTO algorithm. The first part of the
work is dedicated to the theory behind the sufficient conditions for
feasibility and optimality (SCFO), together with their basic implementation
strategy. RTO algorithms enforcing the SCFO are shown to perform as desired in
several numerical examples - allowing for feasible-side convergence to the
plant optimum where algorithms not enforcing the conditions would fail.Comment: Working paper; supplementary material available at:
http://infoscience.epfl.ch/record/18807
Weighted Nash Inequalities
Nash or Sobolev inequalities are known to be equivalent to ultracontractive
properties of Markov semigroups, hence to uniform bounds on their kernel
densities. In this work we present a simple and extremely general method, based
on weighted Nash inequalities, to obtain non-uniform bounds on the kernel
densities. Such bounds imply a control on the trace or the Hilbert-Schmidt norm
of the heat kernels. We illustrate the method on the heat kernel on \dR
naturally associated with the measure with density , with $
Innovation through pertinent patents research based on physical phenomena involved
One can find innovative solutions to complex industrial problems by looking for knowledge in patents. Traditional search using keywords in databases of patents has been widely used. Currently, different computational methods that limit human intervention have been developed. We aim to define a method to improve the search for relevant patents in order to solve industrial problems and specifically to deduce evolution opportunities. The non-automatic, semi-automatic, and automatic search methods use keywords. For a detailed keyword search, we propose as a basis the functional decomposition and the analysis of the physical phenomena involved in the achievement of the function to fulfill. The search for solutions to design a bi-phasic separator in deep offshore shows the method presented in this paper
Balanced homodyne detection in second-harmonic generation microscopy
We demonstrate the association of two-photon nonlinear microscopy with
balanced homodyne detection for investigating second harmonic radiation
properties at nanoscale dimensions. Variation of the relative phase between
second-harmonic and fundamental beams is retrieved, as a function of the
absolute orientation of the nonlinear emitters. Sensitivity down to
approximately 3.2 photon/s in the spatio-temporal mode of the local oscillator
is obtained. This value is high enough to efficiently detect the coherent
second-harmonic emission from a single KTiOPO4 crystal of sub-wavelength size.Comment: 9 pages to appear in Applied Physics Letter
High-temperature oxidation kinetics of NiAl single crystal and oxide spallation as a function of crystallographic orientation
Isothermal and cyclic high-temperature oxidation of NiAl single crystal samples are presented. Oxidations have been carried out at 900, 1050, 1100 and 1150 âŠC on (1 0 0) and (1 1 0) oriented surface. Continuous thermogravimetry in cyclic conditions allows isothermal oxidation kinetics and spalling at each cycle to be followed. Oxidation kinetics are compared between (1 0 0) surface and (1 1 0) surface. (1 0 0) oriented surfaces appeared to oxidize slightly faster than (1 1 0) oriented surfaces. Experimental results of cyclic oxidation are compared to simulated results using a previously published statistical model. Spalling increases when the average oxide scale thickness increases with the number of cycles. Longer tests are necessary to study this evolution during the âsteady-stateâ but no critical oxide thickness was found
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