Using Entropy-Based Methods to Study General Constrained Parameter Optimization Problems

In this letter we propose the use of physics techniques for entropy determination on constrained parameter optimization problems. The main feature of such techniques, the construction of an unbiased walk on energy space, suggests their use on the quest for optimal solutions of an optimization problem. Moreover, the entropy, and its associated density of states, give us information concerning the feasibility of solutions.Comment: 10 pages, 3 figures, references correcte

Dimensionless analysis of the flow of spherical particles in two-phase flow in straight tubes

In the aseptic processing of particulate fluid foods, the residence time distribution of particles and the fluid-to-particle heat transfer are intimately related to the linear and rotational velocities of the particles. The development of models correlating these velocities with fluid and particle characteristics and with operating conditions is therefore very useful, as it provides a fast method to estimate fluid-to-particle heat transfer coefficients without measuring the actual particle velocities. The models can further be used to estimate the average residence time of the particles. Data for modelling particle linear and rotational velocities were obtained by videotaping the flow, along the wall, of individual spherical particles in transparent 2-m long straight tubes. Linear and rotational velocities were correlated with generalized Reynolds, Archimedes and Froude numbers, to the particle-to-fluid density simplex and to the particle/tube diameter ratio. The models obtained had correlation coefficients of 0.89 and 0.86 for the particle linear and rotational velocities, respectively

Dimensionless analysis of fluid-to-particle heat transfer coefficients

Average fluid-to-particle heat transfer coefficients were experimentally determined for spherical aluminium particles heated in car☐ymethylcellulose solutions. Two situations were considered: a still panicle immersed in a moving fluid, and a particle rotating in an otherwise stagnant fluid. Fluid flow rate, rotating particle velocity, particle diameter and fluid rheological properties were varied, covering a large range of the generalized Reynolds (0 to 801) and Prandtl (69 to 5358) numbers. Average heat transfer coefficients ranged between 56 and 2612 W/m2K. The results were compared with values predicted by published dimensionless correlations, showing that correlations based on a Fro¨szling-type equation were more adequate. It was found that the contribution due to natural convection should be considered for proper correlation of the results at low Reynolds numbers. The results also show the importance of the fluid velocity profile

Modelling respiration rate of fresh fruits and vegetables for modified atmosphere packages: a review

Respiration rate and gas exchange through the package material are the processes involved in creating a modified atmosphere inside a package that will extend shelf life of fresh fruits and vegetables. Thus, modelling respiration rate of the selected produce is crucial to the design of a successful modified atmosphere packaging (MAP) system. In this paper, general aspects of the respiration process are presented. The major methods for measuring respiration rates, along with their advantages and limitations are discussed. Factors affecting the respiration rate and respiratory quotient are outlined, stressing the importance of temperature, O2 and CO2 concentrations, and storage time. Respiration rate models in the literature are also reviewed. 2002 Elsevier Science Ltd. All rights reserved

(Un)targeted analysis to unravel critical interactions between sugars and phenolics in Strecker aldehydes formation in beverages

info:eu-repo/semantics/publishedVersio

Adubação não radicular com duas fontes de zinco em Coffea arábica L. "mundo novo" (B.Rodr.) Choussy

A trial was carried out on an eight old coffee plantation with visible zinc problems. The plantation was situated nearly the city of Jaú (22º30'S, 48º30'W). State of São Paulo, Brazil. The soil is classified as medium texture Oxisol of low base saturation (Latossol Vermelho Amarelo - fase arenosa). The pulverization program started in november 1977, followed in march and July 1978 (heavy harvest) and ended in march and July 1979 (light harvest). Is should be mentioned that a well reconized characteristic of arábica coffe is its habit of biennial bearing, a very heavy harvest is most often followed by a light load the next year. The following treatments and amounts of chemicals per cova hole (4 trees) were tested in accordance with a random block design: 1. 1 g of zinc (zinc sulphate, 0.5%) 2. 3 g of nitrogen (urea, 1.3%) 3. 1 g of zinc + 3 g of nitrogen (zinc sulphate 0.5% + urea 1.3%) 4. 0.25 g, 0.50 g, 1.00 g, 2.00 g of zinc plus 0.75 g, 1.50 g, 3.00 g and 6.00 of nitrogen (correspondent to NZN* 15-0-0-5 as 0.75%, 1-5%, 3.0% and 6.0% by v/v). Foliar absorption data were obtained by collecting the 3rd and 4th pairs of the coffee leaves and analysed them for N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn. The main results may be summarized as follows: 1. The maximum calculated yields of clean coffee were obtained by the applications of 5.84 1 of NZN (1.13%) per hectare. 2. The applications of zinc sulphate (0.5%) and urea (1.3%) together or separate did not affected the coffee bean production. 3. The applications of 15.0 1 of NZN per hectare reduced the coffee yields. 4. Leaf damages and burning symptoms were observed by the applications of urea (1.3%) plus zinc sulphate (0.5%) and larger doses than 7.5 1 of NZN per hectare. 5. Leaf tissue analysis show that the concentrations of the elements were affecred by the age of the leaves and by the yields of the coffee trees. 6. The applications of increasing doses of NZN causes an increase in the concentration of zinc, manganese and boron in the leaves and decreased the concentration in calcium and potassium the leaves. 7. The concentration of zinc in the leaves associated with the heavy harvest, in July, was 70.0 ppm.Em cafezal com 8 anos de idade, com deficiência visível de zinco, situado em um Latossol Amarelo - fase arenosa, do município de Jaú, SP, procederam-se pulverizações em novembro, março e julho de 1978 (grande safra) e março e julho de 1979 (pequena safra), O delineamento experimental foi de blocos ao acaso e constou dos seguintes tratamentos, nas doses por planta: lg de zinco (sulfato de zinco 0,5%), 3g de nitrogênio (uréia 1,3%), lg de zinco + 3g de nitrogênio (sulfato de zinco 0,5% + uréia 1,3%) e 0,25g, 0,50g, 1 ,00g e 2,00g de zinco juntamente com 0,75g, l,50g, 3,00g e 6,00g de nitrogênio (respectivamente NZN 15-0-0-5 * a 0,75%, 3,00% e 6,00% v/v). Na época das pulverizaçoes foram coletadas amostras de 3º e 4º pares de folhas, e determinados os teores de nitrogênio, fósforo, potássio, cálcio, magnésio, boro, cobre, ferro, manganês e zinco. Os resultados mostraram que: a) a produção máxima calculada de café beneficiado foi 3-009,4 kg/ha, obtida com pulverizaçao de 5,84 1 de NZN por hectare (NZN 1 ,17%) ; b) o sulfato de zinco e a uréia, juntos ou isoladamente, não afetaram a produção; c) a dose de 15,0 1 de NZN por hectare diminuiu a produção; d) as aplicações de uréia (1,3%) + sulfato de zinco (0,5%) e de doses de NZN superiores a 7,51/ha provocaram injúrias visíveis nas folhas. Esse efeitos se agravaram com dosagens de 15 1 e 30 1 de NZN por hectare; e) as concentrações dos nutrientes nas folhas foram afetadas de maneira diferente pelas épocas de amostragem e pela produção do cafeeiro; f) a aplicação de doses crescentes de NZN provocou aumento nas concentrações de zinco, manganês e boro e diminuição nas de cálcio e potássio nas folhas, em determinadas épocas da grande ou pequena safra; g) a concentração de zinco em julho, relacionada com a maior produção do cafeeiro, foi 70 ppm

Using EcoYieldSAFE to compare soil carbon dynamics under future climate in two contrasting agroforestry systems

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Alternating Minimization, Scaling Algorithms, and the Null-Cone Problem from Invariant Theory

Alternating minimization heuristics seek to solve a (difficult) global optimization task through iteratively solving a sequence of (much easier) local optimization tasks on different parts (or blocks) of the input parameters. While popular and widely applicable, very few examples of this heuristic are rigorously shown to converge to optimality, and even fewer to do so efficiently. In this paper we present a general framework which is amenable to rigorous analysis, and expose its applicability. Its main feature is that the local optimization domains are each a group of invertible matrices, together naturally acting on tensors, and the optimization problem is minimizing the norm of an input tensor under this joint action. The solution of this optimization problem captures a basic problem in Invariant Theory, called the null-cone problem. This algebraic framework turns out to encompass natural computational problems in combinatorial optimization, algebra, analysis, quantum information theory, and geometric complexity theory. It includes and extends to high dimensions the recent advances on (2-dimensional) operator scaling. Our main result is a fully polynomial time approximation scheme for this general problem, which may be viewed as a multi-dimensional scaling algorithm. This directly leads to progress on some of the problems in the areas above, and a unified view of others. We explain how faster convergence of an algorithm for the same problem will allow resolving central open problems. Our main techniques come from Invariant Theory, and include its rich non-commutative duality theory, and new bounds on the bitsizes of coefficients of invariant polynomials. They enrich the algorithmic toolbox of this very computational field of mathematics, and are directly related to some challenges in geometric complexity theory (GCT)

Cryopreservation of collared peccary (Pecari tajacu) semen using different freezing curves, straw sizes, and thawing rates

AbstractThe objective of this study was to verify the effect of different freezing curves, straw sizes, and thawing rates on the cryopreservation of collared peccary semen. Twelve ejaculates were obtained from captive adult males by electroejaculation, and evaluated for sperm motility, kinetic rating, viability, morphology, and functional membrane integrity. The ejaculates were diluted in a coconut water extender (ACP-116c) with egg yolk and glycerol, packaged into 0.25mL or 0.50mL plastic straws and cryopreserved in liquid nitrogen following a slow (−10°C/min) or a fast (−40°C/min) freezing curve. After one week, samples were thawed at 37°C/1min or 70°C/8s and evaluated as reported for fresh semen, and also for kinematic parameters (computerized analysis). A significant decrease in sperm motility and kinetic rating was observed after glycerol addition at 5°C and also after thawing for all the treatments (P<0.05). Regarding post-thaw semen variables, no differences were verified between freezing curves when the same straw size and thawing rate were taken as reference (P>0.05). In general, values for sperm characteristics found after thawing at 37°C were better preserved than at 70°C (P<0.05), both in the use of 0.25mL or 0.50mL straws, which were similar for semen packaging (P>0.05). The evaluation of the kinematic parameters of sperm motility confirmed these results at values varying from 20% to 30% motile sperm for the samples thawed at 37°C, and values fewer than 12% motile sperm for samples thawed at 70°C (P<0.05). In conclusion, we recommend the use of a fast freezing curve that reduces the time spent on the cryopreservation of collared peccary semen, which could be packaged both in 0.25mL or 0.50mL straws, but the thawing should be conducted at 37°C/1min