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Using the example of acrylonitrile-butadiene-styrene (ABS) copolymer, the effect of the gap (thread) diameter for five printing velocity at 230°C on the thread temperature and velocity at the nozzle exit was investigated using the ANSYS Fluent simulation program. It was shown that the change of the gap diameter had a significant impact on the tested parameters.

The seams of a baseball have a large influence in the dynamics of non-spinning balls, so that the Navier–Stokes equations must be solved if one wants to have a full description of the throw. However, the rugosity of the baseball makes difficult to study computationally the flow around it. Therefore only a few investigations have been reported on the subject. In this work, the flow around a ball is studied in a two dimensional domain by means of direct numerical simulations. The goal of this investigation is to characterize the effects produced by a single seam on the flow around the ball. In our 2D simulations the air flow is perpendicular to the cross section of the ball. In this context, the problem coincides with the flow around a circular cylinder with a bump on its surface that mimics the seam. The methodology consists in solving the compressible Navier–Stokes equations using a finite-difference method. The implementation was carried out using the ZEUS-3D magnetohydrodynamic code, originally designed for astrophysical purposes. Here we adapted the code to include a solid body (the ball), this will extend the potential use of the code to engineering problems. The flow is validated by comparison of the smooth case with previous findings reported in literature for smooth circular cylinders at similar R e . Near the surface of the ball, the results for the pressure coefficient are in agreement with previous studies for the front face however, we found some differences at the rear side of the ball. A systematic study is performed with a seam located at different angles from 0°to 90°. The resulting flow features are compared to the results of the smooth ball. Each seam produces large disturbations in pressure around it and smooth disturbations along the surface of the ball. We found a direct relationship between the local effects in pressure and the pressure drag and with the lift coefficient. The seams located at the angles of 30°, 85°and 90°produce the large effects in the aerodynamic coefficients and the wake. The results provide a better understanding of the dynamics of baseballs and other sport balls and might have direct application to the flow around modified cylinders.

Continuous inkjet systems are commonly used to print expiry date labels for food products. These systems are designed to print on flat surfaces; however, a lot of food products package have a cylindrical shape (e.g., bottled and canned products) which causes an enlargement in characters at the ends of the label. In this work, we present an algorithm to correct this defect by calculating the extra-distance that an ink drop travels when the printing surface approaches an elliptic cylinder. Each charged ink drop is modeling as a solid particle which is affected by the air drag, Earth’s gravitation, and voltage due to the electrical field that causes the perturbation in the ink drop path. Numerical results show the correction of the enlargement mentioned above by varying the electric field along the width of the label. In addition, the equation and the values of a second electric field to correct the printing’s inclination caused by the method of the system’s operation are presented.

For the production of sodium sulfate, a brine is crystallized and crystals of glauber salt are generated by this process. The phase data related to the most common sodium sulfate minerals are as follows: mirabilite (Na2SO4 ⋅ 10H2O), tenardite (Na2SO4), glauberite (Na2SO4 ⋅ CaSO4), astrakanite (Na2SO4 ⋅ MgSO4 ⋅ 4H2O). The units commonly used to express the phases are moles of salt per 1000 moles of water. These latter units simplify the construction of the commonly employed four-sided Janecke phase diagrams. The cooling temperature or the speed with which the solution is cooled has an effect on the size and purity, as well as the amount of crystals produced. We seek to establish, through the population balance equations (PBE), which process variables can be modified to obtain a specific crystal size, as well as to validate the mathematical model that best predicts the amount of crystals precipitated as a function of temperature. The adjustment by least squares, cubic splines, pitzer equations and Lagrange interpolation is tested. The experimental results agree with the characteristics of the proposed models.

The Magnus effect is responsible for deflecting the trajectory of a spinning baseball. The deflection at the end of the trajectory can be estimated by simulating some similar trajectories or by clustering real paths; however, previous to this study, there are no reports for a detailed connection between the initial throw conditions and the resulting deflection by using. The only approximation about this is the PITCHf/x algorithm, which uses the kinematics equations. In this work, deflections from simulated spinning throws with random linear and angular velocities and spin axis parallel to the horizontal plane are analyzed in their polar representation. A cardioid function is proposed to express the vertical deflection as response of the angular velocity. This is based on both theoretical arguments from the ball movement equations and from the numerical solution of such equations. We found that the vertical deflection fits a cardioid model as function of the Magnus coefficient and the spin angle, for a set of trajectories with initial linear velocities symmetrically distributed around the direction of motion. A variation of the model can be applied to estimate the radial deflection whereas an extended model should be explored for trajectories with velocities asymmetrically distributed. The model is suitable for many applications: from video games to pitching machines. In addition, the model approaches to the results obatined with the kinematic equations, which serves as validation of the PITCHf/x algorithm.

The Weierstrass and Riemann walks are non trivial discrete random processes to model and characterize the underlying “noise” in the dynamics of fluctuations for out of equilibrium systems, and, in more general contexts, to simulate complex dynamics like order-disorder phase transitions and anomalous diffusion properties in physical, biological and financial systems. In this work simple algorithms, implemented in GNU-R, for both Riemann and Weierstrass discrete processes are presented. Explicit formulas for the probability distributions of n steps are obtained. Finally a way to connect both random processes is commented.

The movement of a knuckleball depends on the seams of the baseball strongly, as a consequence a lift force proportional to the square of the ball velocity is occasioned. In this work we develop a model as a function of the position of the seams to compute the lift coefficient that appears in the lift force acting in upward direction, for four-seam (4S) and two-seam (2S) orientations of the ball. The result of the model is consistent with experimental data. In addition, deviations caused by lift force are calculated for all angles in the 4S and 2S orientations and some trajectories are generated.

Diamond films exhibits excellent properties as high thermal conductivity and low electrical conduc tivity, due to phonon phenomena. Also, its strong valence bonds allow gap values up to 5.4 ev. When diamond films are exposed to beta radiation, some electrons pass from the valence to the conduction band, and other stayed trapped between both bands. If the diamond is heated after beta radiation, the trap electrons could be encountered with their respectively holes or positrons emitting light at different frequencies, this phenomenon is called thermoluminescence (TL). The goal in this work is to demonstrate that the intensity of a glow curve can be adjusted by a three parameters Weibull distribution.

An important topic in the study of the time series behavior and, in particular, meteorological time series is the long-range dependence. This paper explores the behavior of rainfall variations in different periods, using long-range correlations analysis. Semivariograms and Hurst exponent were applied to historical data in different pluviometric stations of the Río Bravo-San Juan watershed, at the hydrographic RH-24 Mexico region. The database was provided by the Water National Commission (CONAGUA). Using the semivariograms, the Hurst exponent was obtained and used as an input to perform a cluster analysis of rainfall stations. Groups of homogeneous samples that might be useful in a regional frequency analysis were obtained through the process. © 2015 Francisco Gerardo Benavides-Bravo et al.

El uso del biogás como fuente de energía renovable ha cobrado auge en las últimas décadas, por beneficio en el sector energético y ambiental. El biogás está compuesto principalmente por metano, el cual tiene un potencial de calentamiento global 21 veces mayor que el dióxido de carbono, este último se genera durante la combustión. El principal problema para el aprovechamiento del biogás es su contenido de sulfuro de hidrógeno: es un gas altamente corrosivo y toxico. Se han desarrollado diversas tecnologías para la remoción de sulfuro de hidrógeno, entre ellas se encuentran las basadas en adsorción sobre óxidos metálicos. Uno de los retos para la remoción de sulfuro de hidrógeno a partir de óxidos metálicos es la capacidad de adsorción, la cual está estrechamente relacionada con el área superficial. Dado que los óxidos metálicos nanoparticulados exhiben un área superficial relativamente alta representan un área de oportunidad en el desarrollo de procesos de remoción de sulfuro de hidrógeno. La adsorción en metales es una opción para la remoción de sulfuro de hidrógeno a pequeña escala, porque es una operación unitaria de operación sencilla. Se planteó el uso de nanopartículas de ferritas (Fe3O4) y de ferritas de manganeso (Fe2.5Mn0.5O4) para la remoción de sulfuro de hidrógeno, se diseñó un sistema experimental para estudiar su comportamiento durante la remoción de sulfuro de hidrógeno en lecho fijo, y basado en parámetro experimentales se modeló y proyectó el fenómeno a un prototipo (probado in situ), finalmente se determinaron algunos factores de eficiencia para estimar los impactos ambientales que tenga el uso de las nanopartículas como medio de adsorción a escala de pequeña industria. Barrientos et al [1], en su trabajo de tesis doctoral sintetizo ferritas y ferritas de manganeso de alta área superficial. En este trabajo se busca una aplicación de dichas nanopartículas en la remoción de sulfuro de hidrógeno. Se presenta un Ecodiseño de la implementación de un sistema de remoción de sulfuro de hidrógeno basado en adsorción con ferritas nanopartículas. 11 Para abordar el objetivo, el trabajo se organizó en tres etapas la síntesis y caracterización de los materiales, el Ecodiseño y optimización con modelado computacional, y finalmente la evaluación de impacto ambiental. La evaluación del impacto se limita al cálculo de los indicadores de PMI (Process Mass Intensify) y E-Factor (Factor de eficiencia).