9,925 research outputs found
Lexicographic optimization for the multi-container loading problem with open dimensions for a shoe manufacturer
Motivated by a real-world application, we present a multi-container loading problem with 3-open
dimensions. We formulate it as a biobjective mixed-integer nonlinear program with lexicographic
objectives in order to reflect the decision maker’s optimization priorities. The first objective is to
minimize the number of containers, while the second objective is to minimize the volume of those
containers. Besides showing the NP-hardness of this sequential optimization problem, we provide
bounds for it which are used in the three proposed algorithms, as well as, on their evaluation when a
certificate of optimality is not available. The first is an exact parametric-based approach to tackle the
lexicographic optimization through the second objective of the problem. Nevertheless, given that the
parametric programs correspond to large nonlinear mixed-integer optimizations, we present a heuristic
that is entirely mathematical-programming based. The third algorithm enhances the solution quality of
the heuristic. These algorithms are specifically tailored for the real-world application. The effectiveness
and efficiency of the devised heuristics is demonstrated with numerical experiments
Dinâmica espaço-temporal do parque caffeiro da Região de Três Pontas - MG.
A região de Três Pontas é uma das regiões cafeeiras mais importantes do Brasil e do mundo. O municÃpio é considerado o maior produtor mundial de café. Por esse motivo, conhecer a extensão e a localização desse parque cafeeiro torna-se de extrema importância. O objetivo desse trabalho foi analisar esse parque cafeeiro no tempo e no espaço, por meio de geotecnologias. No trabalho foram utilizadas imagens TM/Landsat de quatro diferentes datas, contemplando um perÃodo de sete anos de estudo. Foram confeccionados os mapas de uso da terra para os anos de 2000, 2003, 2005 e 2007. Por meio de ferramentas de análise espacial do sistema de informação geográfica SPRING, conclui-se que, durante esse perÃodo, o parque cresceu 7,45%. As áreas de café em produção aumentaram 11,24%, o que provavelmente elevou a produtividade da região. Não foram encontrados padrões de mudança no crescimento do parque
Caucasian Familial Moyamoya Syndrome With Rare Multisystemic Malformations
Moyamoya disease is an idiopathic progressive steno-occlusive disorder of the intracranial arteries located at the base of the brain. It is associated with the development of compensatory extensive network of fine collaterals. Moyamoya disease is considered syndromic when certain genetic or acquired disorders such as polycystic kidney disease, neurofibromatosis,
or meningitis are also present. Although the genetic contribution in moyamoya is
indisputable, its cause and pathogenesis remain under discussion. Herein, we report a rare occurrence of moyamoya syndrome in two European Caucasian siblings in association with unusual multisystemic malformations (polycystic kidney disease in one, and intestinal duplication cyst in the other). The karyotype was normal. No mutation in the RFN213 gene was found, and none of the HLA types linked to moyamoya disease or described in similar familial cases were identified. By describing these multisystemic associations, polycystic
kidney disease for the second time, and intestinal malformation for the first time in the literature, our report expands the phenotypic variability of moyamoya syndrome. The coexistence of disparate malformations among close relatives suggests an underlying
common genetic background predisposing to structural or physiological abnormalities in
different tissues and organs
Chaos in black holes surrounded by gravitational waves
The occurrence of chaos for test particles moving around Schwarzschild black
holes perturbed by a special class of gravitational waves is studied in the
context of the Melnikov method. The explicit integration of the equations of
motion for the homoclinic orbit is used to reduce the application of this
method to the study of simple graphics.Comment: 15 pages, LaTex
Experimental observation of two-dimensional fluctuation magnetization in the vicinity of T_c for low values of the magnetic field in deoxygenated YBa_2Cu_3O_{7-x}
We measured isofield magnetization curves as a function of temperature in two
single crystal of deoxygenated YBaCuO with T_c = 52 and 41.5 K. Isofield MvsT
were obtained for fields running from 0.05 to 4 kOe. The reversible region of
the magnetization curves was analyzed in terms of a scaling proposed by Prange,
but searching for the best exponent . The scaling analysis carried
out for each data sample set with =0.669, which corresponds to the
3D-xy exponent, did not produced a collapsing of curves when applied to MvsT
curves data obtained for the lowest fields. The resulting analysis for the Y123
crystal with T_c = 41.5 K, shows that lower field curves collapse over the
entire reversible region following the Prange's scaling with =1,
suggesting a two-dimensional behavior. It is shown that the same data obeying
the Prange's scaling with =1 for crystal with T_c = 41.5 K, as well
low field data for crystal with = 52 K, obey the known two-dimensional
scaling law obtained in the lowest-Landau-level approximation.Comment: 4 pages, 3 figure
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