Algoritmo para determinar un fluxo de custo minimo

Network flow problems arise whenever items must be shipped through a capacitated network to meet customers demand . In the minimal cost flow problem, the items must be distributed so as to mínimize costs. We present a new variant of the dual-simplex algorithm to this problem which is valid when there are no cycles with negative cost

Application of DMAIC method in an industrial case study

Purpose. In the present work DMAIC methodology is implemented in a Portuguese enterprise. The main goal is to reduce the percentage of non-conformities in an injection molded part for the automotive industry, through the elimination of defects that appear after painting. Design/methodology/approach. The DMAIC method was adopted to find an optimal set of factors that reduce the existing non-conformities. Along the five DMAIC phases, different quality tools were implemented to identify the root causes of the problem and to develop an action plan to reduce defects and minimize the process variability. Findings. In the application of this method, teamwork and brainstorming were essential for satisfactory results in a short period of time. A key finding is that the analysis of the possible causes that gave rise to the problem must be carried out separately, in order to easily identify the changes that created a significant improvement in the process. Research limitations/implications. The project is not fully completed since some of the improvement actions are being implemented. Originality/value. This paper describes a practical application of DMAIC methodology that contributed to reduce part defects and improve the production process of a Portuguese company.The authors would like to acknowledge Fehst Componentes, Lda. for providing physical, technical and human resources and to be strongly involved on the development of this study; to the founds provide by National Funds through FCT - Portuguese Foundation for Science and Technology, References UIDB/05256/2020 and UIDP/05256/2020

Integrable variant of the one-dimensional Hubbard model

A new integrable model which is a variant of the one-dimensional Hubbard model is proposed. The integrability of the model is verified by presenting the associated quantum R-matrix which satisfies the Yang-Baxter equation. We argue that the new model possesses the SO(4) algebra symmetry, which contains a representation of the $\eta$-pairing SU(2) algebra and a spin SU(2) algebra. Additionally, the algebraic Bethe ansatz is studied by means of the quantum inverse scattering method. The spectrum of the Hamiltonian, eigenvectors, as well as the Bethe ansatz equations, are discussed

DESENVOLVIMENTO, PRODUTIVIDADE E GENES DE REFERÊNCIA DE GENÓTIPOS DE COFFEA SPP. SOB TEMPERATURAS ADVERSAS

O aquecimento global pode promover mudanças no zoneamento agroclimatológico do cafeeiro, e consequêntimente no cenário mundial da cafeicultura. O objetivo geral deste trabalho foi de avaliar o desenvolvimento, produtividade e genes de referência de genótipos de Coffea spp. Sob temperaturas adversas. O trabalho foi dividido em 5 capítulos: Capítulos 1 e 2: O aumento do nível de CO2 atmosférico e as elevadas temperaturas, podem promover alterações nas plantas. Neste caso os objetivos deste estudo foram: ocorrência de fotoinibição (PSII), seguida de uma caracterização dos mecanismos de proteção da planta, incluindo a dinâmica de pigmentos fotossintéticos, sistemas antioxidantes enzimáticos e não-enzimáticos, a quantificação da família rafinose Oligossacarídeos (RFOs), quantificação de proteína de choque térmico, o estudo detalhado de genes de referência para normalização em análise de expressão de genes selecionados com papéis potenciais na aclimatação por calor. O experimento foi realizado adotando-se o arranjo experimental do tipo fatorial simples, com delineamento inteiramente casualizado, sendo empregado dois fatores, compostos por dois níveis de CO2 e outro com quatro níveis de temperatura. Foram utilizados dois genótipos de Coffea arabica (cv. Icatu e IPR 108) e um Coffea canephora (cv. Conilon clone 153), cultivadas em vasos de 80 L. O experimento foi realizado em duas câmaras regiões as quais possuem o risco de mudança de zoneamento agrícola do C. arabica para C. canephora, como é o caso deste estudo. Os objetivos destes estudos foram de: (a) avaliar a capacidade produtiva de 28 diferentes genótipos de Coffea canephora desenvolvidos no clima de altitude elevada. (b) Caracterizar a taxa de crescimento de genótipos de Coffea canephora cultivados em altitude elevada. (c) Identificar genótipos com potencial para ser cultivado na região sul do cerrado de Goiás. O experimento foi realizado no Instituto Federal de Educação, Ciência e Tecnologia Goiano Campus Morrinhos, Goiás. Utilizando-se 28 genótipos de C. canephora, multiplicados por clones e sementes. O delineamento utilizado foi em blocos casualizados, com quatro repetições, sendo cada repetição composta por cinco plantas. Foram avaliadas as características: Produtividade em sacas/ha em quatro safras, taxa de crescimento e quantificação de nutrientes acumulados nas folhas coletadas no inverno e verão. Os resultados obtidos para o cultivo de C. canephora em altitude revelam variabilidade genética entre os genótipos, condição que favorece a obtenção de ganhos com a seleção clonal, também foi observado elevada herdabilidade, resultado que indica a alta precisão quanto a seleção de genótipos superiores. Os genótipos de C. canephora que se destacaram em produtividade, estabilidade e adaptabilidade foram: os genótipo 3V da variedade Vitória; NV2; NV8; P1; VERDIM TA e A1, deve-se considerar que dentre esses seis genótipos considerados superiores existem diferentes graus de similaridade o que depende da característica em questão. As taxas de crescimento de ramos plagiotrópicos e ortotrópicos dos materiais genéticos de C. canephora foram afetados negativamente durante período em que as temperaturas mínimas foram abaixo de 17ºC. Para a maioria dos nutrientes observa-se maiores valores médias em folhas coletadas no inverno. A análise de componentes principais indica que os grupos de genótipos de C. canephora alteram as relações entre objetos (genótipos) e descritores (teor de nutrientes) de acordo com e época de coletadas das folhas (inverno e Verão)

Job security among healthcare workers in Guangdong, China

Objective: The objective of this study was to explore the sense of job security and its influencing factors among healthcare workers in Guangdong, China. Methods: This cross-sectional study used stratified random sampling to enroll healthcare workers employed by hospitals across Guangdong province between September 2020 and October 2020. Results: A total of 4,173 questionnaires were distributed, and 4,076 were returned for an effective recovery rate of 97.68%. The overall score for the sense of security was 64.85 ± 20.09, and the item means score was 2.95 ± 0.91. Multiple-linear regression analysis showed that work experience (years), education level, job position, specialty unit, employment type, marital status, job satisfaction, WPV frequency, daily sleep duration, weekly overtime hours, average monthly earnings (RMB), hospital level, and region were significantly associated with senses of poor security among healthcare workers (all P < 0.05). Conclusions: Hospital workers in Guangdong reported relatively low levels of job security. Levels of job security were significantly associated with multiple factors which could be addressed by hospital practices to improve the sense of job security among healthcare workers. Copyrightinfo:eu-repo/semantics/publishedVersio

Optimal cutting directions and rectangle orientation algorithm

The first stage in hierarchical approaches to Floorplan Design defines topological relations between components that intend to optimize a given objective in a circuit board. These relations determine a placement that is subsequently optimized in order to minimize a cost measurement (that will probably be one between chip area or perimeter). The board optimization gives rise to multiple subproblems that need to be answered in order to obtain a good solution. Among the most relevant ones we find the problem of defining the optimal orientation of cells and the definition of the optimal cutting sequence that minimize the placement board area. We will present a generalization of an algorithm due to Stockmeyer so that it obtains a solution that not only defines the optimal cell orientation but also the slicing cuts sequence that will lead to this optimal orientation and overall area minimization.http://www.sciencedirect.com/science/article/B6VCT-3TN9R05-B/1/3ed2fa5acf5e53dff08af5423738ac8

A variational approach for the Quantum Inverse Scattering Method

We introduce a variational approach for the Quantum Inverse Scattering Method to exactly solve a class of Hamiltonians via Bethe ansatz methods. We undertake this in a manner which does not rely on any prior knowledge of integrability through the existence of a set of conserved operators. The procedure is conducted in the framework of Hamiltonians describing the crossover between the low-temperature phenomena of superconductivity, in the Bardeen-Cooper-Schrieffer (BCS) theory, and Bose-Einstein condensation (BEC). The Hamiltonians considered describe systems with interacting Cooper pairs and a bosonic degree of freedom. We obtain general exact solvability requirements which include seven subcases which have previously appeared in the literature.Comment: 18 pages, no eps figure