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51.
Christoforos Anagnostopoulos Dimitris K. Tasoulis Niall M. Adams David J. Hand 《Advances in Data Analysis and Classification》2009,3(3):243-261
Modern technology has allowed real-time data collection in a variety of domains, ranging from environmental monitoring to healthcare. Consequently, there is a growing need for algorithms capable of performing inferential tasks in an online manner, continuously revising their estimates to reflect the current status of the underlying process. In particular, we are interested in constructing online and temporally adaptive classifiers capable of handling the possibly drifting decision boundaries arising in streaming environments. We first make a quadratic approximation to the log-likelihood that yields a recursive algorithm for fitting logistic regression online. We then suggest a novel way of equipping this framework with self-tuning forgetting factors. The resulting scheme is capable of tracking changes in the underlying probability distribution, adapting the decision boundary appropriately and hence maintaining high classification accuracy in dynamic or unstable environments. We demonstrate the scheme’s effectiveness in both real and simulated streaming environments. 相似文献
52.
J.K. Yakinthos P.F. Ikonomou T. Anagnostopoulos 《Journal of magnetism and magnetic materials》1978,8(4):308-312
Magnetic properties of nine RE2Au compounds have been studied in fields of up to 19 kOe in the temperature range 4.2K–300K. It has been found that all compounds are paramagnetic at room temperature except Gd2Au. The compounds with Pr, Nd, Ho, Er and Tm exhibit Curie-Weiss behaviour with paramagnetic moments in close agreement with those expected for the free RE3+ ion. The moment of gold was found to be zero. The compounds with Pr, Nd, Tb, Dy, Er and Tm are antiferromagnetic at low temperatures. It appears that Ho2Au is ferromagnetically ordered below 4.5 K. No evidence for magnetic ordering was found for Y2Au. The compound with Tb exhibits metamagnetic behaviour. 相似文献
53.
Sudhir Burman Dixit N. Sathyanarayana Augoustinos Anagnostopoulos 《Transition Metal Chemistry》1979,4(6):364-367
Summary 4,4-Bipyridyl (4,4-bipy) complexes of ferrous salts of the Fe(4,4-bipy)x(anion)y type (where x or y=1 or 2) and of ferric salts of the Fe(4,4-bipy)m(anion)n type (where m=1 or 2 and n=3) have been synthesised. Elemental analyses, i.r. and electronic spectra, magnetic and Mössbauer studies have been performed to characterize the complexes. 4,4-Bipy and some anions are inferred to act as bridging ligands. The magnetic moments, electronic and Mössbauer spectra suggest that the complexes are of high spin type with distorted octahedral structures. The value of the isomer shift and quadrupole splitting are discussed in terms of bonding of the ligand and anions. 相似文献
54.
55.
G.L. Borchert D. Anagnostopoulos M. Augsburger C. Castelli D. Chatellard J.P. Egger P. El Khoury M. Elble H. Gorke D. Gotta P. Hauser P. Indelicato K. Kirch S. Lenz N. Nelms K. Rashid O.W.B. Schult Th. Siems L.M. Simons 《Hyperfine Interactions》2000,127(1-4):149-155
At the LEAR facility, CERN, antiprotonic Lα transitions in light elements have been investigated with a focussing crystal
spectrometer. The high resolution of the experiment allowed for the first time to resolve in
H the 23P0 state from the close lying states 23P2, 21P1, and 23P1. In
D the corresponding transitions were found to be more than an order of magnitude broader. To a large extent the results for
H support the meson exchange model.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
56.
D. Gotta D. S. Covita D. F. Anagnostopoulos H. Fuhrmann H. Gorke A. Gruber A. Hirtl T. Ishiwatari P. Indelicato E. -O. Le Bigot M. Nekipelov V. Pomerantsev M. Popov J. M. F. dos Santos Ph. Schmid L. M. Simons M. Trassinelli J. F. C. A. Veloso J. Zmeskal 《Physics of Particles and Nuclei》2014,45(1):181-183
The (3p — 1s) X-ray transition to the muonic hydrogen ground state was measured with a highresolution crystal spectrometer. The assumption of a statistical population of the hyperfine levels of the muonic hydrogen ground state was directly confirmed by the experiment and measured values for the hyperfine splitting can be reported. The measurement supplements studies on line broadening effects induced by Coulomb de-excitation hindering the direct extraction of the pion-nucleon scattering lengths from pionic hydrogen and deuterium X-ray lines. 相似文献
57.
Konstantinos P. Anagnostopoulos Georgios Mamanis 《Computational Management Science》2011,8(3):259-279
This paper investigates the ability of Multiobjective Evolutionary Algorithms (MOEAs), namely the Non-dominated Sorting Genetic
Algorithm II (NSGA-II), Pareto Envelope-based Selection Algorithm (PESA) and Strength Pareto Evolutionary Algorithm 2 (SPEA2),
for solving complex portfolio optimization problems. The portfolio optimization problem is a typical bi-objective optimization
problem with objectives the reward that should be maximized and the risk that should be minimized. While reward is commonly
measured by the portfolio’s expected return, various risk measures have been proposed that try to better reflect a portfolio’s
riskiness or to simplify the problem to be solved with exact optimization techniques efficiently. However, some risk measures
generate additional complexities, since they are non-convex, non-differentiable functions. In addition, constraints imposed
by the practitioners introduce further difficulties since they transform the search space into a non-convex region. The results
show that MOEAs, in general, are efficient and reliable strategies for this kind of problems, and their performance is independent
of the risk function used. 相似文献
58.
Th. Strauch F. D. Amaro D. F. Anagnostopoulos P. Bühler D. S. Covita H. Gorke D. Gotta A. Gruber A. Hirtl P. Indelicato E. -O. Le Bigot M. Nekipelov J. M. F. dos Santos Ph. Schmid S. Schlesser L. M. Simons M. Trassinelli J. F. C. A. Veloso J. Zmeskal 《The European Physical Journal A - Hadrons and Nuclei》2011,47(7):1-19
The strong-interaction shift ε 1s πD and broadening Γ 1s πD in pionic deuterium have been determined in a high statistics study of the πD(3p-1s) X-ray transition using a high-resolution crystal spectrometer. The pionic deuterium shift will provide constraints for the pion-nucleon isospin scattering lengths extracted from measurements of shift and broadening in pionic hydrogen. The hadronic broadening is related to pion absorption and production at threshold. The results are ε 1s πD = (?2356 ± 31) meV (repulsive) and Γ 1s πD meV yielding for the complex πD scattering length a πD = [?(24.99±0.33)+i(6.22 ?0.26 +0.12 )] × 10?3 m π ?1 . From the imaginary part, the threshold parameter for pion production is obtained to be α = (251 ?11 +5 ) μb. This allows, in addition, and by using results from pion absorption in 3He at threshold, the determination of the effective couplings g 0 and g 1 for s-wave pion absorption on isoscalar and isovector NN pairs. 相似文献