Search algorithms for improving the pareto front in a timetabling problem with a solution network-based robustness measure

Annals of Operations Research - We develop search algorithms based on local search, and a matheuristic that solves a set of mixed integer programming models to improve the robustness of a set of...     

A family of Numerov-type exponentially fitted predictor-corrector methods for the numerical integration of the radial Schrödinger equation

A family of predictor-corrector exponential Numerov-type methods is developed for the numerical integration of the one-dimensional Schrödinger equation. The formula considered contains certain free parameters which allow it to be fitted automatically to exponential functions. The new methods are very simple and integrate more exponential functions than both the well-known fourth-order Numerov-type exponentially fitted methods and the sixth algebraic order Runge-Kutta-type methods. Numerical results also indicate that the new methods are much more accurate than the other exponentially fitted methods mentioned above.     

Energy resolution improvement of NaI(Tl) scintillation detectors by means of a timing discrimination method

Gamma-ray energy spectrum of a ¹³⁷Cs radioisotope was obtained by using a NaI(Tl) scintillation detector. Improvement of the energy resolution of the detector was aimed. To achieve this, constant fraction timing method was used. Energy resolution of the photopeak of the isotope was improved from 7.1 to 6.7% through the timing application.     

Comparison of resolving time values of different scintillation detectors in the coincidence experiments

The resolving time values of the coincidence spectrometers composed by NaI(Tl) inorganic, BC408 type and BC418 type organic scintillation detectors were obtained in this work. For this purpose, fast–fast coincidence measurements were carried out. Best timing performance was obtained by BC418 type plastic scintillator for various source-detector distances.     

Time resolution investigations for general purpose plastic scintillation detectors in different thicknesses

Time spectra of ⁹⁰Sr, ¹³⁷Cs and ²⁰⁷Bi radioactive sources were obtained by using a BC 400 type plastic scintillation detectors in different thicknesses. Time resolution values through the time spectra were obtained by means of leading edge and constant fraction timing methods. The obtained time resolution values from leading edge method were compared with those of constant fraction timing method.     

Implications of a stochastic microscopic Finsler cosmology

Within the context of supersymmetric space-time (D-particle) foam in string/brane-theory, we discuss a Finsler-induced cosmology and its implications for (thermal) dark matter abundances. This constitutes a truly microscopic model of dynamical space-time, where Finsler geometries arise naturally. The D-particle foam model involves point-like brane defects (D-particles), which provide the topologically non-trivial foamy structures of space-time. The D-particles can capture and emit stringy matter and this leads to a recoil of D-particles. It is indicated how one effect of such a recoil of D-particles is a back-reaction on the space-time metric of Finsler type which is stochastic. We show that such a type of stochastic space-time foam can lead to acceptable cosmologies at late epochs of the Universe, due to the non-trivial properties of the supersymmetric (BPS like) D-particle defects, which are such so as not to affect significantly the Hubble expansion. The restrictions placed on the free parameters of the Finsler type metric are obtained from solving the Boltzmann equation in this background for relic abundances of a Lightest Supersymmetric Particle (LSP) dark matter candidate. It is demonstrated that the D-foam acts as a source for particle production in the Boltzmann equation, thereby leading to enhanced thermal LSP relic abundances relative to those in the Standard ??CDM cosmology. For D-particle masses of order TeV, such effects may be relevant for dark matter searches at colliders. The latter constraints complement those coming from high-energy gamma-ray astronomy on the induced vacuum refractive index that D-foam models entail. We also comment briefly on the production mechanisms of such TeV-mass stringy defects at colliders, which, in view of the current LHC experimental searches, will impose further constraints on their couplings.