A Reinforced Tabu Search Approach for 2D Strip Packing:

This paper discusses a particular “packing” problem, namely the two dimensional strip packing problem, where a finite set of objects have to be located in a strip of fixed width and infinite height. The variant studied considers regular items, rectangular to be precise, that must be packed without overlap, not allowing rotations. The objective is to minimize the height of the resulting packing. In this regard, the authors present a local search algorithm based on the well-known tabu search metaheuristic. Two important components of the presented tabu search strategy are reinforced in attempting to include problem knowledge. The fitness function incorporates a measure related to the empty spaces, while the diversification relies on a set of historically “frozen” objects. The resulting reinforced tabu search approach is evaluated on a set of well-known hard benchmark instances and compared with state-of-the-art algorithms

A Dedicated Genetic Algorithm for Two-Dimensional Non-Guillotine Strip Packing

This paper introduces DGA, a new dedicated genetic algorithm for a two-dimensional (2D) non-guillotine strip packing problem (2D-SPP). DGA integrates two key features: a hierarchical fitness function and a problem-specific crossover operator (WAX for "wasted area based crossover"). The fitness function takes into account not only the final height of the strip (to be minimized), but also the wasted areas. The goal of the meaningful (and "visual”) WAX crossover operator is to preserve the good property of parent packing configurations. To assess the proposed DGA, experimental results are shown on a set of well-known zero-waste benchmark instances and compared with previously reported genetic algorithms as well as the best performing meta-heuristic algorithms

Aspectos clínico-patológicos del linfosarcoma o leucocis linfática canina

Se presentan los aspectos clínicos, hematológicos e histopatológicos más relevantes de 15 casos de lin-fosarcoma canino diagnosticados en la Facultad de Ciencias Veterinarias y Pecuarias de la Universidad de Chile. Los antecedentes se analizan en relación al diagnóstico de la enfermedad.AbstractThe clinical, hermatologic and pathologic features of 15 canine lymphosarcoma cases, examined at the Faculty of Veterinary Sciences of the University of Chile , were reviewed in order to determine the most important factors in the disease

Aspectos clínico-patológicos del linfosarcoma o leucocis linfática canina

Se presentan los aspectos clínicos, hematológicos e histopatológicos más relevantes de 15 casos de lin-fosarcoma canino diagnosticados en la Facultad de Ciencias Veterinarias y Pecuarias de la Universidad de Chile. Los antecedentes se analizan en relación al diagnóstico de la enfermedad.AbstractThe clinical, hermatologic and pathologic features of 15 canine lymphosarcoma cases, examined at the Faculty of Veterinary Sciences of the University of Chile , were reviewed in order to determine the most important factors in the disease

Qualitative feed restriction on productive performance and lipid metabolism in broiler chickens

A trial was carried out to evaluate the effect of qualitative restriction at different rearing phases on liver fatness and plasma triglycerides without impairing the productive performance of broiler chickens. One hundred and seventy-six mate chicks were randomly assigned to four treatments and reared in battery brooders (16 pens with I I birds each) from I to 49-day-old. In the control group, chicks were fed a starter diet (1 to 28-day-old) with 3,300kcal ME/kg of diet and 22.5% CP; grower diet (29 to 42-day-old) 3,300kcal ME/kg of diet and 18.2% CP; and the finisher diet (43 to 49-day-old) 3,300kcal ME/kg and 18.2% CP. Three restrict groups were fed a low 2,800kcal ME/kg of diet and 24% CP from 7 to 14-day-old (treatment 1); from 7 to 21-day-old (treatment 2); and from 22 to 35-day-old (treatment 3). All treatments were fed control diet before and after the feed restriction period. Feed intake was not affected during the feed restriction period; nevertheless, weight gain was lower (P < 0.05) for chicks fed restricted diet from 7 to 2 1 and from 2 1 to 35-day-old. At the end of each restriction period, scores of liver for fatty infiltration were higher in restricted birds compared to control birds, although no changes were detected in plasma triglyceride levels. On the 49th day of age, less intracellular fatty infiltration was observed in the liver of previously restricted birds compared to control birds, and weight gain was also lower in the restricted groups. Moreover, triglyceride plasma levels were similar among treatments, but decreased in 12-hour-fasted broilers compared to non-fasted birds. The low energy:protein ratio diet affected weight gain and fatty infiltration in the liver, but had no effect on plasma levels of triglycerides.Aplicou-se restrição alimentar qualitativa em frangos de corte, em diferentes fases do crescimento, para reduzir a infiltração gordurosa do fígado e os triglicerídeos plasmáticos, sem influir nas respostas produtivas. Distribuíram-se aleatoriamente 176 pintos machos em quatro tratamentos. As aves foram alojados em baterias (16 gaiolas com 11 aves cada) e foram criados de 1 a 49 dias de idade. No grupo controle as aves foram alimentadas com dieta inicial (1-28 dias) com 3.300kcal EM/kg/dieta e 22,5% de proteína bruta (PB; dieta de crescimento (29-42 dias) com 3.300kcal EM/kg/dieta e 20,9% de PB; dieta de acabamento (43-49 dias de idade) 3.300kcal EM/kg/dieta e 18,2% de PB. As aves nos três grupos sob restrição foram alimentadas com dieta com 2.800kcal de EM/kg/dieta e 24% de PB de 7 aos 14 dias de idade (tratamento 2), de 7 aos 21 dias de idade (tratamento 2) e de 22 aos 35 dias de idade (tratamento 3). Todas as aves dos tratamentos sob restrição foram alimentadas com a dieta controle antes e depois do período de restrição alimentar. Ao final de cada período de restrição foi observada uma maior infiltração gordurosa no fígado (representado pela composição química e escore histológico). Também não houve diferenças entre os triglicerídeos plasmáticos, quando comparado com o controle. Aos 49 dias de idade, o ganho de peso total e a infiltração gordurosa no fígado, foram menores nos grupos restritos. Os níveis de triglicérides plasmáticos, entretanto, foram semelhantes entre os tratamentos, mas reduziram nas aves com aplicação de jejum de 12 horas, quando comparados com aves sem jejum. A baixa relação energia/proteína da dieta afetou o ganho de peso e a infiltração gordurosa no fígado, mas não alterou os valores de triglicérides plasmáticos

Producción de leche y grasa de vacas libres e infectadas subclínicamente con el virus de la leucosis bovina

The objective of the present study was to compare prospectively the milk and fat production, standardized to 305-day mature equivalent of bovine leukemia virus (BLV) naturally infected (89) and uninfected (104) cows. The animals were Holstein and Holstein x Chilean-Friesian, from a herd of the región Metropolitana, Chile, representing standard management for dairy cattle and with a known epidemiological condition related to BLV infection.BLV seropositive cows produced 6,501 ± 1,505 kg of milk and 168 ± 53 kg of fat (305-day, M.E), compared to 6,677 ± 1,728 of milk and 166 ± 46 kg of fat from seronegative cows. No statistical differences in milk and fat production were observed between the two groups of cows using variance analysis (P ≥ 0.05). No significant differences were also observed in milk and fat production, according to the number of lactations, between BLV seronegative and seropositive cows.Se comparó la producción real de leche y de grasa, proyectada a 305 días y estandarizada a madurez equivalente de 89 vacas seropositivas y 104 negativas a la infección con el virus leucosis bovina (VLB), con el objeto de evaluar el efecto del estado subclínico de infección. Los animales utilizados eran de raza Holstein y cruza Holstein x Frisón Negro, pertenecientes a una lechería de la Región Metropolitana, con manejo estándar para la zona y una situación conocida de la dinámica de la infección con el VLB. Los anticuerpos contra la glicoproteína del VLB fueron detectados por inmunodifusión en gel de agar en tres exámenes semestrales sucesivos. Los animales seropositivos presentaron una producción de 6.501 ± 1.505 kg de leche estandarizada a madurez equivalente y de 168 ± 53 kg de grasa, las cuales no fueron estadísticamente diferentes (p ≥ 0,05) a las vacas seronegativas con una producción de leche de 6.677 ± 1.728 kg y de grasa de 166 ± 46 kg. Cuando se compararon las producciones de leche y de grasa de ambos grupos de animales, de acuerdo al número de la lactancia, tampoco se observaron diferencias significativas. Se concluye que para las condiciones de manejo y los niveles productivos señalados, la infección subclínica con el VLB no afectaría la producción láctea

A Tabu Search Algorithm with Direct Representation for Strip Packing

Date du colloque&nbsp;: 04/2009International audienceThis paper introduces a new tabu search algorithm for a two-dimensional (2D) Strip Packing Problem (2D-SPP). It integrates several key features: A direct representation of the problem, a satisfaction-based solving scheme, two different complementary neighborhoods, a diversification mechanism and a particular tabu structure. The representation allows inexpensive basic operations. The solving scheme considers the 2D-SPP as a succession of satisfaction problems. The goal of the combination of two neighborhoods is (to try) to reduce the height of the packing while avoiding solutions with (hard to fill) tall and thin wasted spaces. Diversification relies on a set of historically “interesting” packings. The tabu structure avoids visiting similar packings. To assess the proposed approach, experimental results are shown on a set of well-known benchmark instances and compared with previously reported tabu search algorithms as well as the best performing algorithms.</p