282 research outputs found
Index Information Algorithm with Local Tuning for Solving Multidimensional Global Optimization Problems with Multiextremal Constraints
Multidimensional optimization problems where the objective function and the
constraints are multiextremal non-differentiable Lipschitz functions (with
unknown Lipschitz constants) and the feasible region is a finite collection of
robust nonconvex subregions are considered. Both the objective function and the
constraints may be partially defined. To solve such problems an algorithm is
proposed, that uses Peano space-filling curves and the index scheme to reduce
the original problem to a H\"{o}lder one-dimensional one. Local tuning on the
behaviour of the objective function and constraints is used during the work of
the global optimization procedure in order to accelerate the search. The method
neither uses penalty coefficients nor additional variables. Convergence
conditions are established. Numerical experiments confirm the good performance
of the technique.Comment: 29 pages, 5 figure
Robust finite-time stability design via linear matrix inequalities
For linear systems with polytopic uncertainties, the problem of robust finite-time stabilization is reduced to a system of Linear Matric Inequalities
Analytic Gain and Phase Margin Design
In 5, algorithms are presented for analytic gain and phase margin design. Without special care however, the compensator computed with this algorithm is not a real rational function. In 3, it is shown that with some care, a real rational compensator for phase margin design can be computed from the theory in 5. In this paper both gain and phase margin problems are reduced to interpolation problems with positive-real functions, which saves a step in the algorithm shown in 5, where interpolation is done with bounded-real functions, in the case of gain margin design
LQ Robust Synthesis With Non-fragile Controllers: The Static State Feedback Case
This paper describes the synthesis of Non-fragile or Resilient regulators for linear systems. The general framework for fragility is described using state space methodologies and the LQH static state feedback case is examined in detail. We discuss the multiplicative structured uncertainties case and propose remedies of the fragility problem. The benchmark problem is taken as example to show how an uncertain or resilient static state feedback controller can affect the performance of the system
Benchmark calculation of n-3H and p-3He scattering
The n-3H and p-3He elastic phase-shifts below the trinucleon disintegration
thresholds are calculated by solving the 4-nucleon problem with three different
realistic nucleon-nucleon interactions (the I-N3LO model by Entem and
Machleidt, the Argonne v18 potential model, and a low-k model derived from the
CD-Bonn potential). Three different methods -- Alt, Grassberger and Sandhas,
Hyperspherical Harmonics, and Faddeev-Yakubovsky -- have been used and their
respective results are compared. For both n-3H and p-3He we observe a rather
good agreement between the three different theoretical methods. We also compare
the theoretical predictions with the available experimental data, confirming
the large underprediction of the p-3He analyzing power.Comment: 18 pages, 9 figure
Proton-He elastic scattering at low energies
We present new accurate measurements of the differential cross section
and the proton analyzing power for proton-He
elastic scattering at various energies. A supersonic gas jet target has been
employed to obtain these low energy cross section measurements. The
distributions have been measured at = 0.99, 1.59,
2.24, 3.11, and 4.02 MeV. Full angular distributions of have been
measured at = 1.60, 2.25, 3.13, and 4.05 MeV. This set of
high-precision data is compared to four-body variational calculations employing
realistic nucleon-nucleon (NN) and three-nucleon (3N) interactions. For the
unpolarized cross section the agreement between the theoretical calculation and
data is good when a potential is used. The comparison between the
calculated and measured proton analyzing powers reveals discrepancies of
approximately 50% at the maximum of each distribution. This is analogous to the
existing `` Puzzle'' known for the past 20 years in nucleon-deuteron
elastic scattering.Comment: 22 pages, 9 figures, to be published in Physical Review C, corrected
reference 4
The Ay Problem for p-3He Elastic Scattering
We present evidence that numerically accurate quantum calculations employing
modern internucleon forces do not reproduce the proton analyzing power, A_y,
for p-3He elastic scattering at low energies. These calculations underpredict
new measured analyzing powers by approximately 30% at E_{c.m.} = 1.20 MeV and
by 40% at E_{c.m.} = 1.69 MeV, an effect analogous to a well-known problem in
p-d and n-d scattering. The calculations are performed using the complex Kohn
variational principle and the (correlated) Hyperspherical Harmonics technique
with full treatment of the Coulomb force. The inclusion of the three-nucleon
interaction does not improve the agreement with the experimental data.Comment: Latex file, 4 pages, 2 figures, to be published on Phys. Rev. Let
Factors influencing consumer wine choice: The case of wine tourism
This research was undertaken to examine the relationship between the wine tourism activities of consumers and their subsequent wine choices. Exploratory research was undertaken giving specific attention to wine tourism, first, as a factor of influence on decision-making, second, on levels of consumer involvement and third on long-term consumer loyalty. A convenience sample of 12 wine consumers in Dublin participated in the study. Semi-structured in-depth interviews were used to gather the qualitative data used. The findings clearly establish links made by consumers between their wine tourism experiences and their subsequent wine purchase preferences. The findings highlight the importance of facilitating the co-creation of memorable wine tourism experiences as a determinant of improved consumer involvement as well as the development of long-term consumer loyalty. Implications for industry practitioners suggest a continued focus on the provision of unique wine tourism experiences; while the findings support the theoretical links between consumers own past experiences and their use as a valuable information source when making purchase decisions
Preoperative risk score for prediction of long-term outcomes after hepatectomy for intrahepatic cholangiocarcinoma: Report of a collaborative, international-based, external validation study.
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