Simulation-Based Control of Complex Material Handling Systems

2008-2009Material Handling (MH) consists in the movement and storage of parts, in a manufacturing or distribution process, from one location to another. Material Handling Systems (MHSs) are everywhere in production plants, assembly lines, product distribution, logistics, intermodal activities (railways, road transportation, container ships, etc..). They usually are distributed, sometimes itinerant and often mixed manned and automated. Although not adding value in the manufacturing process, MH usually influences great part of a company’s operation costs, especially, for example, in the food distribution chain. Due to the increasing demand for a high variety of products, flexibility and efficiency are two important keywords in MHSs. Optimizing MH activities means having shorter response times and an increased throughput of the plant. The importance of this optimization process is very high in today’s companies. Nowadays, the interest in this process is growing rapidly since several new technologies, like the Radio Frequency Identification (RFID) are available which finally allow to introduce an automation level to operating MHSs, almost without stopping operations and at a very low cost. In MHSs control iusses involve the problem of the optimal sequencing and scheduling of short-term activities. The so-called problem of "Dispatching” consists in defining a procedure to assign resources to missions. This is often made by using heuristic rules called Dispaching rules. For control purposes, a model of the system is necessary. Due to the complex and heterogeneous nature of MHSs, modeling approaches proposed in the literature are typically very specific and context-dependent. Moreover, the strong combinatorial nature of the control problem, and the presence of a great number of constraints to be considered, usually make the design of a control solution very tough. To devise a closed form analytical control action can require a great computational effort and could result not so convenient. Indeed, turbulence and variations in the input set of the system can suddenly make not more adequate a hardly designed control action. Thus, the choice of Dispatching rules as control actions, despite producing only local optimum solutions, is very usual for MHSs. Dispatching rules, indeed, result in a more reasonable and robust way to control MHSs since they are effective and computationally inexpensive. In the absence of a closed form control solution, Simulation is fundamental to evaluate the effects of a control action which cannot be analytically predicted. The outcome of the application of a rule or another can be easily tested via simulation and this is the reason why having a good model assumes a further major importance. In this thesis a unique arcchitecture for the modeling and the control of complex MHSs has been proposed.VIII n.s

The Physics of the B Factories

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C

Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV

We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with next-to-leading order (NLO) quantum chromodynamics (QCD)

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe