772 research outputs found

    Natural remanent magnetization of Rumanova chondrite (H5) acquired by the shock metamorphisms S3

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    The natural remanent magnetization (NRM) of Rumanova (H5) chondrite was studied to focus on the shock remagnetization characterized by shock level S3. The NRM was examined by AF and thermal demagnetization, temperature dependencies of magnetization and coercivity, magnetic anisotropy, microscopic features using magnetic fluid technique and chemical compositions. Based on these results, Rumanova carries the stable NRM by a fine-grained taenite with 48 wt% Ni in cloudy taenite, although large amount of the soft NRM component with the magnetic anisotropy is overprinted. These taenite grains were produced by disorder from tetrataenite due to heating between 525℃ and 950℃ during shock metamorphism when the parent body collided with the asteroids. Rumanova was remagnetized below 530℃ in the cooling stage by the local magnetic field from strongly magnetized FeNi grains. From these viewpoints, the NRM of Rumanova was not original, but it was remagnetized during shock metamorphism

    High School Graduation and Dropout Rates in the Pikes Peak Region of Colorado: A Spatial Analysis of School Proximity to Military Installations

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    The purpose of this project was to examine graduation and dropout rates for high school students to determine if a correlation could be found with respect to the relative school distance from a military installation in the Pikes Peak region. Spatial analysis and Ordinary Least Squares analysis were used to build a linear regression model to predict student graduation and dropout rates. The results for the total student population for graduation rates and for dropout rates showed no statistically significant correlation with respect to the relative proximity to a military installation. Detailed analysis revealed that several minority and gender subgroups showed statistically significant correlations

    A Tabu List-Based Algorithm for Capacitated Multilevel Lot-Sizing with Alternate Bills of Materials and Co-Production Environments

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    [EN] The definition of lot sizes represents one of the most important decisions in production planning. Lot-sizing turns into an increasingly complex set of decisions that requires efficient solution approaches, in response to the time-consuming exact methods (LP, MIP). This paper aims to propose a Tabu list-based algorithm (TLBA) as an alternative to the Generic Materials and Operations Planning (GMOP) model. The algorithm considers a multi-level, multi-item planning structure. It is initialized using a lot-for-lot (LxL) method and candidate solutions are evaluated through an iterative Material Requirements Planning (MRP) procedure. Three different sizes of test instances are defined and better results are obtained in the large and medium-size problems, with minimum average gaps close to 10.5%.This paper shows the results of the project entitled "Algoritmo heuristico basado en listas tabu para la planificacion de la produccion en sistemas multinivel con listas de materiales alternativas y entornos de coproduccion" supported by Universidad de la Costa and Universitat Politecnica de Valencia.Romero-Conrado, AR.; Coronado-Hernandez, J.; Rius-Sorolla, G.; García Sabater, JP. (2019). A Tabu List-Based Algorithm for Capacitated Multilevel Lot-Sizing with Alternate Bills of Materials and Co-Production Environments. Applied Sciences. 9(7):1-17. https://doi.org/10.3390/app9071464S11797Karimi, B., Fatemi Ghomi, S. M. T., & Wilson, J. M. (2003). The capacitated lot sizing problem: a review of models and algorithms. Omega, 31(5), 365-378. doi:10.1016/s0305-0483(03)00059-8Martí, R., & Reinelt, G. (2010). Heuristic Methods. Applied Mathematical Sciences, 17-40. doi:10.1007/978-3-642-16729-4_2Barany, I., Van Roy, T. J., & Wolsey, L. A. (1984). Strong Formulations for Multi-Item Capacitated Lot Sizing. Management Science, 30(10), 1255-1261. doi:10.1287/mnsc.30.10.1255Eppen, G. D., & Martin, R. K. (1987). Solving Multi-Item Capacitated Lot-Sizing Problems Using Variable Redefinition. Operations Research, 35(6), 832-848. doi:10.1287/opre.35.6.832Maes, J., McClain, J. O., & Van Wassenhove, L. N. (1991). Multilevel capacitated lotsizing complexity and LP-based heuristics. European Journal of Operational Research, 53(2), 131-148. doi:10.1016/0377-2217(91)90130-nBuschkühl, L., Sahling, F., Helber, S., & Tempelmeier, H. (2008). Dynamic capacitated lot-sizing problems: a classification and review of solution approaches. OR Spectrum, 32(2), 231-261. doi:10.1007/s00291-008-0150-7Drexl, A., & Kimms, A. (1997). Lot sizing and scheduling — Survey and extensions. European Journal of Operational Research, 99(2), 221-235. doi:10.1016/s0377-2217(97)00030-1Glock, C. H., Grosse, E. H., & Ries, J. M. (2014). The lot sizing problem: A tertiary study. International Journal of Production Economics, 155, 39-51. doi:10.1016/j.ijpe.2013.12.009KUIK, R., SALOMON, M., VAN WASSENHOVE, L. N., & MAES, J. (1993). LINEAR PROGRAMMING, SIMULATED ANNEALING AND TABU SEARCH HEURISTICS FOR LOTSIZING IN BOTTLENECK ASSEMBLY SYSTEMS. IIE Transactions, 25(1), 62-72. doi:10.1080/07408179308964266Standard Price List—AMPLhttps://ampl.com/products/standard-price-list/Seeanner, F., Almada-Lobo, B., & Meyr, H. (2013). Combining the principles of variable neighborhood decomposition search and the fix&optimize heuristic to solve multi-level lot-sizing and scheduling problems. Computers & Operations Research, 40(1), 303-317. doi:10.1016/j.cor.2012.07.002Hung, Y.-F., & Chien, K.-L. (2000). A multi-class multi-level capacitated lot sizing model. Journal of the Operational Research Society, 51(11), 1309-1318. doi:10.1057/palgrave.jors.2601026Kang, Y., Albey, E., & Uzsoy, R. (2018). Rounding heuristics for multiple product dynamic lot-sizing in the presence of queueing behavior. Computers & Operations Research, 100, 54-65. doi:10.1016/j.cor.2018.07.019BERRETTA, R., FRANÇA, P. M., & ARMENTANO, V. A. (2005). METAHEURISTIC APPROACHES FOR THE MULTILEVEL RESOURCE-CONSTRAINED LOT-SIZING PROBLEM WITH SETUP AND LEAD TIMES. Asia-Pacific Journal of Operational Research, 22(02), 261-286. doi:10.1142/s0217595905000510KIMMS, A. (1996). Competitive methods for multi-level lot sizing and scheduling: tabu search and randomized regrets. International Journal of Production Research, 34(8), 2279-2298. doi:10.1080/00207549608905025Sabater, J. P. G., Maheut, J., & Garcia, J. A. M. (2013). A new formulation technique to model materials and operations planning: the generic materials and operations planning (GMOP) problem. European J. of Industrial Engineering, 7(2), 119. doi:10.1504/ejie.2013.052572Maheut, J., & Sabater, J. P. G. (2013). Algorithm for complete enumeration based on a stroke graph to solve the supply network configuration and operations scheduling problem. Journal of Industrial Engineering and Management, 6(3). doi:10.3926/jiem.550Rius-Sorolla, G., Maheut, J., Coronado-Hernandez, J. R., & Garcia-Sabater, J. P. (2018). Lagrangian relaxation of the generic materials and operations planning model. Central European Journal of Operations Research, 28(1), 105-123. doi:10.1007/s10100-018-0593-0Maheut, J., Garcia-Sabater, J. P., & Mula, J. (2012). The Generic Materials and Operations Planning (GMOP) Problem Solved Iteratively: A Case Study in Multi-site Context. IFIP Advances in Information and Communication Technology, 66-73. doi:10.1007/978-3-642-33980-6_8Maheut, J. P. D. (s. f.). Modelos y Algoritmos Basados en el Concepto Stroke para la Planificación y Programación de Operaciones con Alternativas en Redes de Suministro. doi:10.4995/thesis/10251/29290Glover, F. (1989). Tabu Search—Part I. ORSA Journal on Computing, 1(3), 190-206. doi:10.1287/ijoc.1.3.190Glover, F., Taillard, E., & Taillard, E. (1993). A user’s guide to tabu search. Annals of Operations Research, 41(1), 1-28. doi:10.1007/bf02078647Chelouah, R., & Siarry, P. (2000). Tabu Search applied to global optimization. European Journal of Operational Research, 123(2), 256-270. doi:10.1016/s0377-2217(99)00255-6Raza, S. A., Akgunduz, A., & Chen, M. Y. (2006). A tabu search algorithm for solving economic lot scheduling problem. Journal of Heuristics, 12(6), 413-426. doi:10.1007/s10732-006-6017-7Cesaret, B., Oğuz, C., & Sibel Salman, F. (2012). A tabu search algorithm for order acceptance and scheduling. Computers & Operations Research, 39(6), 1197-1205. doi:10.1016/j.cor.2010.09.018Li, X., Baki, F., Tian, P., & Chaouch, B. A. (2014). A robust block-chain based tabu search algorithm for the dynamic lot sizing problem with product returns and remanufacturing. Omega, 42(1), 75-87. doi:10.1016/j.omega.2013.03.003Li, J., & Pan, Q. (2015). Solving the large-scale hybrid flow shop scheduling problem with limited buffers by a hybrid artificial bee colony algorithm. Information Sciences, 316, 487-502. doi:10.1016/j.ins.2014.10.009Hindi, K. S. (1995). Solving the single-item, capacitated dynamic lot-sizing problem with startup and reservation costs by tabu search. Computers & Industrial Engineering, 28(4), 701-707. doi:10.1016/0360-8352(95)00027-xHindi, K. S. (1996). Solving the CLSP by a Tabu Search Heuristic. Journal of the Operational Research Society, 47(1), 151-161. doi:10.1057/jors.1996.13Gopalakrishnan, M., Ding, K., Bourjolly, J.-M., & Mohan, S. (2001). A Tabu-Search Heuristic for the Capacitated Lot-Sizing Problem with Set-up Carryover. Management Science, 47(6), 851-863. doi:10.1287/mnsc.47.6.851.9813Glover, F. (1990). Tabu Search—Part II. ORSA Journal on Computing, 2(1), 4-32. doi:10.1287/ijoc.2.1.4Overview for Create General Full Factorial Designhttps://support.minitab.com/en-us/minitab/18/help-and-how-to/modeling-statistics/doe/how-to/factorial/create-factorial-design/create-general-full-factorial/before-you-start/overview/Perttunen, J. (1994). On the Significance of the Initial Solution in Travelling Salesman Heuristics. Journal of the Operational Research Society, 45(10), 1131-1140. doi:10.1057/jors.1994.183Elaziz, M. A., & Mirjalili, S. (2019). A hyper-heuristic for improving the initial population of whale optimization algorithm. Knowledge-Based Systems, 172, 42-63. doi:10.1016/j.knosys.2019.02.010Chen, C.-F., Wu, M.-C., & Lin, K.-H. (2013). Effect of solution representations on Tabu search in scheduling applications. Computers & Operations Research, 40(12), 2817-2825. doi:10.1016/j.cor.2013.06.003Tabu List Based Algorithm Datasetshttps://github.com/alfonsoromeroc/tlba-gmo

    Applied mathematical modelling for Industrial Engineers

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    [EN] The learning of mathematical modelling techniques can result in a long and tedious process for Industrial Organization Engineering students. It is necessary to combine in a balanced way the theoretical teachings with the modelling of real study cases. In order to make more flexible the theoretical teaching process, multimedia tools of autodidactic learning are provided. A key factor is to evolve from simple models solved through educational programs, such as WinQSB or spreadsheets with embedded solvers to more complex models developed with a high level language of mathematical programming as MPL or GAMS where the models are solved with diverse commercial solvers (CPLEX, GUROBI, XPRESS, etc.) The objective of this paper is to present an innovative methodology to teach mathematical modelling techniques based in: (i) the balance of the theoretical and practical teachings; (ii) the use of multimedia autodidactic tools; and (iii) the formulation and resolution of real study cases through different solvers.[ES] El aprendizaje de técnicas de modelización matemática puede resultar en un proceso largo y tedioso para estudiantes de Ingeniería de Organización Industrial. Es necesario combinar de una forma equilibrada las enseñanzas teóricas con el modelado de casos de estudio reales. Para hacer más flexible el proceso de enseñanza teórica, se proporcionan herramientas multimedia de aprendizaje autónomo. Un factor clave es evolucionar de modelos simples resueltos a través de programas educativos, tales como WinQSB u hojas de cálculo con solucionadores embebidos a modelos más complejos desarrollados con diversos solucionadores comerciales (CPLEX, GUROBI, XPRESS, etc.) El objetivo de esta comunicación es presentar una metodología innovadora para enseñar técnicas de modelización matemática basada en: (a) el equilibrio de las enseñanzas teóricas y prácticas; (b) el uso de herramientas multimedia autodidácticas; y (c) la formulación y resolución de casos de estudio reales a través de diferentes solucionadores.Mula, J.; Poler, R. (2011). Applied mathematical modelling for Industrial Engineers. Modelling in Science Education and Learning. 4:307-318. doi:10.4995/msel.2011.3097SWORD307318

    Supplemental Ascorbate Diminishes DNA Damage Yet Depletes Glutathione and Increases Acute Liver Failure in a Mouse Model of Hepatic Antioxidant System Disruption

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    Cellular oxidants are primarily managed by the thioredoxin reductase-1 (TrxR1)- and glutathione reductase (Gsr)-driven antioxidant systems. In mice having hepatocyte-specific codisruption of TrxR1 and Gsr (TrxR1/Gsr-null livers), methionine catabolism sustains hepatic levels of reduced glutathione (GSH). Although most mice with TrxR1/Gsr-null livers exhibit long-term survival, ~25% die from spontaneous liver failure between 4- and 7-weeks of age. Here we tested whether liver failure was ameliorated by ascorbate supplementation. Following ascorbate, dehydroascorbate, or mock treatment, we assessed survival, liver histology, or hepatic redox markers including GSH and GSSG, redox enzyme activities, and oxidative damage markers. Unexpectedly, rather than providing protection, ascorbate (5 mg/mL, drinking water) increased the death-rate to 43%. In adults, ascorbate (4 mg/g × 3 days i.p.) caused hepatocyte necrosis and loss of hepatic GSH in TrxR1/Gsr-null livers but not in wildtype controls. Dehydroascorbate (0.3 mg/g i.p.) also depleted hepatic GSH in TrxR1/Gsr-null livers, whereas GSH levels were not significantly affected by either treatment in wildtype livers. Curiously, however, despite depleting GSH, ascorbate treatment diminished basal DNA damage and oxidative stress markers in TrxR1/Gsr-null livers. This suggests that, although ascorbate supplementation can prevent oxidative damage, it also can deplete GSH and compromise already stressed livers

    High Efficiency Lipid-Based siRNA Transfection of Adipocytes in Suspension

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    BACKGROUND:Fully differentiated adipocytes are considered to be refractory to introduction of siRNA via lipid-based transfection. However, large scale siRNA-based loss-of-function screening of adipocytes using either electroporation or virally-mediated transfection approaches can be prohibitively complex and expensive. METHODOLOGY/PRINCIPAL FINDINGS:We present a method for introducing small interfering RNA (siRNA) into differentiated 3T3-L1 adipocytes and primary human adipocytes using an approach based on forming the siRNA/cell complex with the adipocytes in suspension rather than as an adherent monolayer, a variation of "reverse transfection". CONCLUSIONS/SIGNIFICANCE:Transfection of adipocytes with siRNA by this method is economical, highly efficient, has a simple workflow, and allows standardization of the ratio of siRNA/cell number, making this approach well-suited for high-throughput screening of fully differentiated adipocytes
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