Numerical Formulation for the Prediction of Solid/Liquid Change of a Binary Alloy

A computational model is presented for the prediction of solid/liquid phase change energy transport including the influence of free convection fluid flow in the liquid phase region. The computational model considers the velocity components of all non-liquid phase change material control volumes to be zero but fully solves the coupled mass-momentum problem within the liquid region. The thermal energy model includes the entire domain and uses an enthalpy like model and a recently developed method for handling the phase change interface nonlinearity. Convergence studies are performed and comparisons made with experimental data for two different problem specifications. The convergence studies indicate that grid independence was achieved and the comparison with experimental data indicates excellent quantitative prediction of the melt fraction evolution. Qualitative data is also provided in the form of velocity vector diagrams and isotherm plots for selected times in the evolution of both problems. The computational costs incurred are quite low by comparison with previous efforts on solving these problems

Rotating light, OAM paradox and relativistic complex scalar field

Recent studies show that the angular momentum, both spin and orbital, of rotating light beams possesses counter-intuitive characteristics. We present a new approach to the question of orbital angular momentum of light based on the complex massless scalar field representation of light. The covariant equation for the scalar field is treated in rotating system using the general relativistic framework. First we show the equivalence of the U(1) gauge current for the scalar field with the Poynting vector continuity equation for paraxial light, and then apply the formalism to the calculation of the orbital angular momentum of rotating light beams. If the difference between the co-, contra-, and physical quantities is properly accounted for there does not result any paradox in the orbital angular momentum of rotating light. An artificial analogue of the paradoxical situation could be constructed but it is wrong within the present formalism. It is shown that the orbital angular momentum of rotating beam comprising of modes with opposite azimuthal indices corresponds to that of rigid rotation. A short review on the electromagnetism in noninertial systems is presented to motivate a fully covariant Maxwell field approach in rotating system to address the rotating light phenomenon.Comment: No figure

Frontier Orbital and Conformational Analysis of a Nematic Liquid Crystal: 4-n-heptyloxy-4´-cyanobiphenyl

687-689The 4-n-heptyloxy-4´-cyanobiphenyl (7OCB) is a member of 4-n-alkoxy-4´-cyanobiphenyl homologous series. This liquid crystal series is well known for its electro-optical properties. The 7OCB compound transforms from crystal to nematic at 53.5°C and nematic to isotropic phase at 75.0°C. Using Hartree-Fock and DFT methods with 6-31G(d,p) basis set, molecular geometry, conformational analysis, electronic structure, MEP, HOMO-LUMO surfaces and molecular parameters of 7OCB molecular system have been investigated. Efforts have been made to elucidate the physico-chemical properties of the 7OCB liquid crystal

Performance Evaluation of Greenhouse Having Passive or Active Heating in Different Climatic Zones of India

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 9 (2007): Performance Evaluation of Greenhouse Having Passive or Active Heating in Different Climatic Zones of India. Manuscript EE 06 011. Vol. IX. May, 2007

Next generation smart manufacturing and service systems using big data analytics

© 2018 Elsevier Ltd This special issue explores advancements in the next generation manufacturing and service systems by examining the novel methods, practical challenges and opportunities in the use of big data analytics. The selected articles analyse a range of scenarios where big data analytics and its applications were used for improving decision making in manufacturing and services sector such as online data analytics, sourcing decisions with considerations for big data analytics, barriers in the adoption of big data analytics, maintenance planning, and multi-sensor data for fault pattern extraction. The paper summarises the discussions on the use of big data analytics in manufacturing and service sectors

A novel approach towards investigating the performance of different PVT configurations integrated on test cells: An experimental study

This study elaborates the theoretical and experimental analysis for the effectiveness of different photovoltaic thermal (PVT) configurations along with their building implications. An experiment was performed on especially designed four identical prototype test cells emphasise the building integration photovoltaic thermal (BiPVT) systems. A comparative analysis of four different possible PVT configurations integrated on identical test cells namely; Case 1: Glass-to-glass PV with duct integrated on a test cell, Case 2: Glass-to -glass PV without duct integrated on a test cell, Case 3: Glass to tedlar PV with duct integrated on a test cell and Case 4: Glass to tedlar PV without duct integrated on a test cell was carried out. Analytical model of the electrical and thermal performance for different cases was developed and experimentally validated in outdoor conditions. On the basis of the correlation coefficient (r) and root mean square percent deviation (e), a fair agreement between theoretically calculated and experimentally observed values is achieved. The glass to glass PV module gives better both electrical and thermal performance with hourly average ηm 12.65% and 12.70% for case 1 and 2 respectively. Similarly, the hourly average ηith was observed 32.77% and 25.44% for case 1 and 2 respectively. Further, thermal load levelling with varying packing factor, mass flow rate of air through the PV integrated duct, absorptivity (degradation effect) and transmittivity (dusting effect) are also discussed

Solar Dryers for Tropical Food Preservation: Thermophysics of Crops, Systems and Components

Drying reduces the moisture content of harvested crops thus slowing decay processes to enable longerterm storage. Solar dryers contain the crop being dried, to enhance solar energy collection incurring lower crop losses than are associated with open-sun drying and recurrent costs than are inherent to uses of fossil-fuels for drying. The influences of key environmental, operational and design parameters for solar dryers are discussed including: (i) psychrometry of drying processes and ambient conditions, (ii) how initial crop properties are converted to final desired product attributes, (iii) feasibility of using powered components such as fans and (iv) air-heating solar collector selection

Interaction of two-dimensional transverse jet with a supersonic mainstream

The interaction of a two dimensional sonic jet injected transversely into a confined main flow was studied. The main flow consisted of air at a Mach number of 2.9. The effects of varying the jet parameters on the flow field were examined using surface pressure and composition data. Also, the downstream flow field was examined using static pressure, pitot pressure, and composition profile data. The jet parameters varied were gapwidth, jet static pressure, and injectant species of either helium or nitrogen. The values of the jet parameters used were 0.039, 0.056, and 0.109 cm for the gapwidth and 5, 10, and 20 for the jet to mainstream static pressure ratios. The features of the flow field produced by the mixing and interaction of the jet with the mainstream were related to the jet momentum. The data were used to demonstrate the validity of an existing two dimensional elliptic flow code

Evaluation of Atmospheric Transmittance for Composite Climate

In this paper, an attempt has been made to estimate the cloudiness/haziness factors and atmospheric transmittances for the composite climate of New Delhi (latitude:28.58o N; longitude: 77.02o E; elevation: 216 m above msl). To predict the hourly variation of beam and diffuse radiation on a horizontal surface for any day, atmospheric transmittances for beam and diffuse radiation have been introduced to take into account the uncertain behaviour of atmospheric conditions. For the present study, the hourly data of global and diffuse solar radiation on a horizontal surface for a period of 11 years (1991–2001) have been used and analyzed using polynomial regression analysis. The data have been obtained from the Indian Meteorological Department, Pune, India. It has been observed that there is about 11% maximum and 01% minimum root mean square error between predicted and observed values of hourly varying beam radiation for clear (blue sky) weather condition