A STUDY ON GENERAL ASSEMBLY LINE BALANCING MODELING METHODS AND TECHNIQUES

The borders of the assembly line balancing problem, as classically drawn, are as clear as any other operations research topic in production planning, with well-defined sets of assumptions, parameters, and objective functions. In application, however, these borders are frequently transgressed. Many of these deviations are internal to the assembly line balancing problem itself, arising from any of a wide array of physical or technological features in modern assembly lines. Other issues are founded in the tight coupling of assembly line balancing with external production planning and management problems, as assembly lines are at the intersection of multiple related problems in job sequencing, part flow logistics, worker safety, and quality. The field of General Assembly Line Balancing is devoted to studying the class of adapted and extended solution techniques necessary in order to model these applied line balancing problems. In this dissertation a complex line balancing problem is presented based on the real production environment of our industrial partner, featuring several extensions for task-to-task relationships, station characteristics limiting assignment, and parallel worker zoning interactions. A constructive heuristic is developed along with two improvement heuristics, as well as an integer programming model for the same problem. An experiment is conducted testing each of these new solution methods upon a battery of testbed problems, measuring solution quality, runtime, and achievement of feasibility. Additionally, a new method for measuring a secondary horizontal line balancing objective is established, based on the options-mix paradigm rather than the customary model-mix paradigm

Chicana/o blasphemy : John Phillip Santos as globalized Chicana/o citizen

Hasta el momento, las teorías poscoloniales más profundas e intuitivas han permitido que los académicos reexaminen la cuestión de la identidad cultural desde perspectivas innovadoras. La más exigente de estas teorías, la de 'hibridez cultural', le ofrece al campo de Estudios Chicanos posibilidades de auto-identificarse que no se entregan a limitaciones de identidad previamente establecidas. En este estudio, se aplican las teorías más destacadas de la 'hibridez cultural' a la memoria "Places left unfinished at the time of creation" de John Phillip Santos para ofrecer una idea más inclusiva y compleja de una experiencia chicana del siglo XXI. A través de la lente de la blasfemia secular se hace un bosquejo de cómo Santos desestabiliza conceptos tradicionales de la identidad chicana para darle validez a una experiencia cultural chicana que no se adhiere a tales obligaciones tradicionales de identidad. Este estudio es optimista en cuanto que inicia una nueva lectura dialéctica de la literatura chicana en general y de la memoria de Santos en particular

Chicana/o blasphemy : John Phillip Santos as globalized Chicana/o citizen

Hasta el momento, las teorías poscoloniales más profundas e intuitivas han permitido que los académicos reexaminen la cuestión de la identidad cultural desde perspectivas innovadoras. La más exigente de estas teorías, la de 'hibridez cultural', le ofrece al campo de Estudios Chicanos posibilidades de auto-identificarse que no se entregan a limitaciones de identidad previamente establecidas. En este estudio, se aplican las teorías más destacadas de la 'hibridez cultural' a la memoria "Places left unfinished at the time of creation" de John Phillip Santos para ofrecer una idea más inclusiva y compleja de una experiencia chicana del siglo XXI. A través de la lente de la blasfemia secular se hace un bosquejo de cómo Santos desestabiliza conceptos tradicionales de la identidad chicana para darle validez a una experiencia cultural chicana que no se adhiere a tales obligaciones tradicionales de identidad. Este estudio es optimista en cuanto que inicia una nueva lectura dialéctica de la literatura chicana en general y de la memoria de Santos en particular

Can simulations reproduce the observed temperature-mass relation for clusters of galaxies?

It has become increasingly apparent that traditional hydrodynamical simulations of galaxy clusters are unable to reproduce the observed properties of galaxy clusters, in particular overpredicting the mass corresponding to a given cluster temperature. Such overestimation may lead to systematic errors in results using galaxy clusters as cosmological probes, such as constraints on the density perturbation normalization sigma_8. In this paper we demonstrate that inclusion of additional gas physics, namely radiative cooling and a possible preheating of gas prior to cluster formation, is able to bring the temperature-mass relation in the innermost parts of clusters into good agreement with recent determinations by Allen, Schmidt & Fabian using Chandra data.Comment: 5 pages, submitted to MNRA

Respondent Understanding in Discrete Choice Experiments : A Scoping Review

Acknowledgements The authors would like to acknowledge the contributions of Brendan Mulhern, who gave feedback on the initial project proposal and helped with the full-text reviews, and Bernadette Carr, the librarian who gave assistance developing and implementing the search strategy. Funding During part of this project, Alison Pearce was supported by a University of Technology Sydney Chancellor’s Postdoctoral Research Fellowship and the University of Technology Sydney International Researcher Development Scheme. Mark Harrison is supported by a Michael Smith Foundation for Health Research Scholar Award 2017 (#16813), and holds the UBC Professorship in Sustainable Health Care, which, between 2014 and 2017, was funded by Amgen Canada, AstraZeneca Canada, Eli Lilly Canada, GlaxoSmithKline, Merck Canada, Novartis Pharmaceuticals Canada, Pfizer Canada, Boehringer Ingelheim (Canada), Hoffman-La Roche, LifeScan Canada, and Lundbeck Canada. The Health Economics Research Unit (HERU) receives funding from the Chief Scientist Office (CSO) of the Scottish Government Health and Social Care Directorates.Peer reviewedPublisher PD

The radial structure of galaxy groups and clusters

Simple self-consistent models of galaxy groups and clusters are tested against the results of high-resolution adiabatic gasdynamical simulations. We investigate two models based on the existence of a 'universal' dark matter density profile and two versions of the beta-model. The mass distribution of relaxed clusters can be fitted by phenomenological formulae proposed in the literature. Haloes that have experienced a recent merging event are systematically less concentrated and show steeper profiles than relaxed objects near the centre. The hot X-ray emitting gas is found to be in approximate hydrostatic equilibrium with the dark matter potential, and it is well described by a polytropic equation of state. Analytic formulae for the gas density and temperature can be derived from these premises. Though able to reproduce the X-ray surface brightness, the beta-model is shown to provide a poor description of our numerical clusters. We find strong evidence of a 'universal' temperature profile that decreases by a factor of 2-3 from the centre to the virial radius, whereas baryon fraction and entropy are monotonically increasing functions. Numerical resolution and entropy conservation play a key role in the shapes of the profiles at small radii.Comment: 16 pages, 19 figures, minor changes to match published versio

The Evolution of the Dark Halo Spin Parameters lambda and lambda' in a LCDM Universe: The Role of Minor and Major Mergers

The evolution of the spin parameter of dark halos and the dependence on the halo merging history in a set of dissipationless cosmological LCDM simulations is investigated. Special focus is placed on the differences of the two commonly used versions of the spin parameter, namely lambda=J*E^1/2/(G*M^5/2) (Peebles 80) and lambda'=J/(sqrt(2)*M_vir*R_vir*V_vir) (Bullock et al. 01). Though the distribution of the spin transfer rate defined as the ratio of the spin parameters after and prior to a merger is similar to a high degree for both, lambda and lambda', we find considerable differences in the time evolution: while lambda' is roughly independent of redshift, lambda turns out to increase significantly with decreasing redshift. This distinct behaviour arises from small differences in the spin transfer during accretion events. The evolution of the spin parameter is strongly coupled with the virial ratio eta:=2*E_kin/|E_pot| of dark halos. Major mergers disturb halos and increase both their virial ratio and spin parameter for 1-2 Gyrs. At high redshifts (z=2-3) many halos are disturbed with an average virial ratio of eta = 1.3 which approaches unity until z=0. We find that the redshift evolution of the spin parameters is dominated by the huge number of minor mergers rather than the rare major merger events.Comment: 10 pages, 11 figures, submitted to MNRA

Fundamental differences between SPH and grid methods

We have carried out a hydrodynamical code comparison study of interacting multiphase fluids. The two commonly used techniques of grid and smoothed particle hydrodynamics (SPH) show striking differences in their ability to model processes that are fundamentally important across many areas of astrophysics. Whilst Eulerian grid based methods are able to resolve and treat important dynamical instabilities, such as Kelvin-Helmholtz or Rayleigh-Taylor, these processes are poorly or not at all resolved by existing SPH techniques. We show that the reason for this is that SPH, at least in its standard implementation, introduces spurious pressure forces on particles in regions where there are steep density gradients. This results in a boundary gap of the size of the SPH smoothing kernel over which information is not transferred.Comment: 15 pages, 13 figures, to be submitted to MNRAS. For high-resolution figures, please see http://www-theorie.physik.unizh.ch/~agertz