Building architectures for data‐intensive science using the ADAGE framework

One of the main activities in data‐intensive science is data analysis. Although there are many popular technologies that can assist scientists in various isolated aspects of data analysis, supporting analysis processes in holistic ways that promote system interoperability, integration and automation, as well as scientific reproducibility and efficient data handling, presents many challenges. A common solution to address these challenges is to find efficient ways of integrating various existing technologies together to meet the analysis needs of scientists (which is similar to the idea behind science gateways). We believe that this solution is essentially an exercise in software design; and in many situations, these challenges should be tackled from a software design perspective. Consequently, this paper reviews different architectural design approaches that can be used to address these challenges and proposes a service‐oriented framework called the Ad Hoc Data Grid Environment, which consists of an architectural pattern and its associated operational guidelines. The guidelines prescribe a number of activities based on an iterative decomposition approach to produce and evolve software architectures according to constantly changing user needs. The framework is demonstrated on a case study involving analysis processes required for conducting financial event studies. Copyright © 2014 John Wiley & Sons, Ltd.     

Assessment of porosity of mortar using ultrasonic Rayleigh waves

The relationship between Rayleigh wave velocity at ultrasonic frequencies and porosity is investigated in dry and fully saturated mortar. Porosity is varied by changing the water/cement ratio. Rayleigh wave (RW) pulse velocity is measured accurately using air-coupled ultrasonic transducers as transmitter and receiver. The experimental results are compared with two single-phase models. Due to relatively weak correlation between RW velocity and porosity, measured data and the models are compared using statistical hypothesis tests. Although the parameters of the model are not accurately predicted, these tests conclude on a reasonable agreement between measured data and the models. This result can be useful to develop simplified models of wave propagation in concrete, or to estimate porosity in concrete cover from ultrasonic measurements.     

Patch recovery based on superconvergent derivatives and equilibrium

In this paper a postprocessing technique is developed for determining first-order derivatives (fluxes, stresses) at nodal points based on derivatives in superconvergent points. It is an extension of the superconvergent patch recovery technique presented by Zienkiewicz and Zhu. In contrast to that technique all flux or stress components are interpolated at the same time, coupled by equilibrium equations at the superconvergent points. The equilibrium equations and use of one order higher degree of interpolation polynomials of stress give a dramatic decrease in error of recovered derivatives even at boundaries.     

Condition number for reliable microwave transistor modeling

An appropriate procedure enabling the evaluation of the sensitivity of a MESFET small-signal model given unavoidable measurement errors is presented in the first section of this article. This technique, which is based on calculation of the condition number, has been applied to an NE 76000 MESFET device. The results obtained enabled us to highlight the difficulties of an accurate MESFET characterization and to predict the equivalent-circuit element errors. In the second part, we introduce a new approach that makes it possible to reduce the sensitivity of the parameters of the model. When applied to the same transistor, this approach enables us to reduce the sensitivity of the model of 30% on average. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 174–181, 2004.     

Ammonia volatilization losses from different fertilizers and effect of several urease inhibitors,CaCl2 and phosphogypsum on losses from urea

The extent of ammonia volatilization losses from urea, ammonium sulphate (AS), and diammonium phosphate (DAP) were determined in soil incubation studies. The effects of some urease inhibitors (thiourea, hyroquinone, 2–4 dinitro phenol and boric acid) and CaCl₂ and phosphogypsum additions on ammonia loss from urea were also studied. Total ammonia volatilization losses were 32.6%, 3.1% and 2.3% of the N applied to the soil as urea, AS and DAP, respectively. Among the chemicals examined in the study, 500 mg H₃BO₃ in 1 kg of the soil decreased the ammonia loss from urea by 21% in comparison with the control. When 50 mg/kg soil of thiourea, 2–4 dinitro phenol or hydroquinone were applied, ammonia volatilization losses were found to be 10%, 3% and 0% less than urea applied alone, respectively. When 2500 mg CaCl₂ was applied to 1 kg of soil with urea, ammonia loss was decreased by 5%. The lowest hydrolysis rate (65%) occurred with the boric acid treatment. The differences between the hydrolysis rates of the other treatments were not statistically significant. Phosphogypsum was found the most effective agent in reducing ammonia losses from urea. When phosphogypsum was mixed at 2.3 times as much as the urea, ammonia loss was about 85% less than that of urea applied alone. Obviously, further work is needed to find out the potential of both boric acid and phosphogypsum as reducing agents of ammonia losses from urea.     

A comparative study of the adsorption and desorption of o-xylene onto bentonite clay and alumina

In this paper, adsorptive performance of natural clay of bentonite type has been investigated as a potential VOC adsorbent on the basis its promising physical-chemical and morphological properties which were compared to commercial gamma-Al(2)O(3) solid. The vapour-solid adsorption isotherms of xylene were measured at different temperatures ranging from 300 to 373 K using dynamical method and the obtained data confronted to classical models such as Langmuir and Freundlich. On the other hand, the solids physico-chemical characteristics and adsorptive performances were correlated to some cost aspects because of their importance for design and engineering of adsorption plant. The results shows the interest of a local clay natural of bentonite type for treatment of VOCs emitted in working places regarding its performances and lower cost.     

Incineration of a small particle of wet sewage sludge: a numerical comparison between two states of the surrounding atmosphere

The main goal of this paper is to elaborate a mathematical model that represents the physics and chemistry involved when a small particle of wet sewage sludge is incinerated. Compared to existing models, our study includes both drying and heterogenous combustion of the pyrloysis residue of the processed sludge. This model relies on the assumption of homogeneous composition and temperature for the particle under study. It includes drying, pyrolysis (controlled by a four successives steps reaction pathway) and combustion of the resulting char. The ability of the model is illustrated using it in two different process conditions (representing thermogravemetric analysis and fluidized bed conditions) in order to investigate the influence of the surrounding atmosphere. It is found, that fluidized bed conditions reduce the burnout time of a small particle by enhancing the rate at which heat is transferred to that particle. It is also shown that high heating rates enhance the tar yield.     

Thermal conductivity and thermal boundary resistance of nanostructures

   

We present a fabrication process of low-cost superlattices and simulations related with the heat dissipation on them. The influence of the interfacial roughness on the thermal conductivity of semiconductor/semiconductor superlattices was studied by equilibrium and non-equilibrium molecular dynamics and on the Kapitza resistance of superlattice's interfaces by equilibrium molecular dynamics. The non-equilibrium method was the tool used for the prediction of the Kapitza resistance for a binary semiconductor/metal system. Physical explanations are provided for rationalizing the simulation results.     

On the effect of the transversal aspect ratio on the double-glazed solar air heater performance

The transversal aspect ratio of solar air heaters (SAHs) is a critical geometric parameter that influences the heat transfer from the absorber plate to the working fluid and, accordingly, the overall heat loss level. The present work addresses the effect of the aspect ratio on the performance of a solar air heating system and the behavior of heat transfer coefficients (HTCs) within it and along the flow channel. A mathematical model of energy-balance equations was formulated to examine and analyze the double-glazed solar air heater thermal behavior. The Eismann correlation, which is more accurate than Holland's correlation, was employed to determine the HTC between the two glass covers. The useful energy, Nusselt number (Nu), efficiency, overall loss, and HTCs as a function of the aspect ratio were evaluated across the collector length. On the basis of the findings, the higher the ratio, the better the efficiency of the SAH. Indeed, increasing the collector's cross-sectional aspect ratio (r) up to 19 increases useful energy efficiency by more than 87%, Nu by 84%, thermohydraulic efficiency from 0.4 to 0.76, and overall heat loss by 1.15 W/(m² K). Furthermore, reducing r from 19 to 2 will improve the collector power from 1.855 to 3.473 kW.