201 research outputs found
A Maintenance Planning Framework using Online and Offline Deep Reinforcement Learning
Cost-effective asset management is an area of interest across several
industries. Specifically, this paper develops a deep reinforcement learning
(DRL) solution to automatically determine an optimal rehabilitation policy for
continuously deteriorating water pipes. We approach the problem of
rehabilitation planning in an online and offline DRL setting. In online DRL,
the agent interacts with a simulated environment of multiple pipes with
distinct lengths, materials, and failure rate characteristics. We train the
agent using deep Q-learning (DQN) to learn an optimal policy with minimal
average costs and reduced failure probability. In offline learning, the agent
uses static data, e.g., DQN replay data, to learn an optimal policy via a
conservative Q-learning algorithm without further interactions with the
environment. We demonstrate that DRL-based policies improve over standard
preventive, corrective, and greedy planning alternatives. Additionally,
learning from the fixed DQN replay dataset in an offline setting further
improves the performance. The results warrant that the existing deterioration
profiles of water pipes consisting of large and diverse states and action
trajectories provide a valuable avenue to learn rehabilitation policies in the
offline setting, which can be further fine-tuned using the simulator.Comment: Published Neural Comput & Applic (2023), 12 pages, 8 Figur
New insights in chronic pain after common operations
The first part of the thesis addresses CPP after laparotomy judged to be caused by adhesions. It aims to assess long term results of laparoscopic adhesiolysis as a treatment for CPP.
The second part of the thesis addresses CPP after inguinal hernia repair (CPIP). It aims to determine whether a self-gripping mesh for open inguinal hernia repair according to Lichtenstein influences the incidence of CPIP.
The third part focuses on the methodological quality and comparability of studies addressing CPIP after Lichtenstein hernioplasty. It aims to assess whether study outcomes are valid and can be compared to each other to make firm conclusions about the best treatment or prevention method for CPIP
Superconductivity-Induced Transfer of In-Plane Spectral Weight in Bi2Sr2CaCu2O8: Resolving a Controversy
We present a detailed analysis of the superconductivity-induced
redistribution of optical spectral weight in Bi2Sr2CaCu2O8 near optimal doping.
It confirms the previous conclusion by Molegraaf et al. (Science 66, 2239
(2002)), that the integrated low-frequency spectral weight shows an extra
increase below Tc. Since the region, where the change of the integrated
spectral weight is not compensated, extends well above 2.5 eV, this transfer is
caused by the transfer of spectral weight from interband to intraband region
and only partially by the narrowing of the intraband peak. We show that the
opposite assertion by Boris et al. (Science 304, 708 (2004)) regarding this
compound, is unlikely the consequence of any obvious discrepancies between the
actual experimental data.Comment: ReVTeX, 9 pages, 8 encapsulated postscript figures, several typo's
correcte
In-plane optical spectral weight transfer in optimally doped BiSrCaCuO
We examine the redistribution of the in-plane optical spectral weight in the
normal and superconducting state in tri-layer \bbb (Bi2223) near optimal doping
( = 110 K) on a single crystal via infrared reflectivity and spectroscopic
ellipsometry. We report the temperature dependence of the low-frequency
integrated spectral weight for different values of the cutoff
energy . Two different model-independent analyses consistently show
that for = 1 eV, which is below the charge transfer gap,
increases below , implying the lowering of the kinetic
energy of the holes. This is opposite to the BCS scenario, but it follows the
same trend observed in the bi-layer compound \bb (Bi2212). The size of this
effect is larger in Bi2223 than in Bi2212, approximately scaling with the
critical temperature. In the normal state, the temperature dependence of
is close to up to 300 K
Optical sum rule in metals with a strong interaction
The restricted optical sum rule and its dependence on the temperature, a
superconducting gap and the cutoff energy have been investigated. As known this
sum rule depends on the cutoff energy and the relaxation rate even for a
homogeneous electron gas interacting with impurities or phonons. It is shown
here that additional dependence of the spectral weight on a superconducting gap
is very small in this model and this effect disappears totally when the
relaxation rate is equal zero. The model metal with a single band is considered
in details. It is well known that for this model there is the dependence of the
sum rule on the temperature and the energy gap even in the case when the
relaxation is absent. This dependence exists due to the smearing of the
electron distribution function and it is expressed in the terms of Sommerfeld
expansion. Here it is shown that these effects are considerably smaller than
that of related with the relaxation rate if the band width is larger than the
average phonon frequency. It is shown also that the experimental data about the
temperature dependence of the spectral weight for the high- materials can be
successfully explained in the framework approach based on the temperature
dependence of the relaxation rateComment: 13 pages, 7 figures, the talk given on Internatinal coference on
theoretical physics, april 11-16,2005, Mosco
Electromagnetic response of superconductors and optical sum rule
The interrelation between the condensation energy and the optical sum rules
has been investigated. It has been shown that the so called 'partial' sum rule
violation is related mainly to a temperature dependence of the relaxation rate
rather than to the appearance of superconductivity itself. Moreover, we
demonstrate that the experimental data on the temperature dependence of the
optical sum rule can be explained rather well by an account of strong
electron-phonon interaction.Comment: 16 pages, 1 figure. Submitted to Solid State Communication
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