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Articles 1 - 18 of 18
Full-Text Articles in Engineering
Should Tortuosity Still Be Used In Upscaling?, Francisco J. Valdes-Parada, Mark L. Porter, Brian D. Wood
Should Tortuosity Still Be Used In Upscaling?, Francisco J. Valdes-Parada, Mark L. Porter, Brian D. Wood
Francisco J. Valdes-Parada
The concept of tortuosity is an integral part of models that describe trans- port in multiscale systems. Traditionally, tortuosity is de#12;ned as the ratio of an e#11;ective path length to the shortest path length in a representative sample of the porous medium microstructure. While the latter can be unambiguously speci#12;ed, the same is not true for the e#11;ective path length, since it changes from one type of transport to another. Consequently, it is possible to have di#11;erent tortuosity values for di#11;erent transport processes taking place in the same system. In order to avoid running into unclear interpretations, we pro- pose …
Intelligent Controller For Smart Base Isolation Of Masonry Structures, Simon Laflamme, T.Y. Yu, Jerome J. Connor
Intelligent Controller For Smart Base Isolation Of Masonry Structures, Simon Laflamme, T.Y. Yu, Jerome J. Connor
Simon Laflamme
In this paper, an intelligent controller to control a smart base-isolated masonry structure is proposed. The smart base isolation consists of rubber bearings and a magnetorheological damper. This semi-active scheme takes advantage of the low power requirement of magnetorheological devices to achieve structural control. The controller is capable of mapping the behaviour of the controlled structure sequentially, using a self-organizing neural network which has time-varying learning rates. This neurocontroller is augmented by a sliding mode controller to account for the uncertainty on the semi-active damping forces. Wavelets are used as functions in the single hidden layer for their capability of …
Proceedings Of The Scientific Conference On Energy And It At Alvsjo Fair, Stockholm March 11-12, 2009 In Connection With The “Energitinget 2009, Dr. Erik Dahlquist, Dr. Jenny Palm
Proceedings Of The Scientific Conference On Energy And It At Alvsjo Fair, Stockholm March 11-12, 2009 In Connection With The “Energitinget 2009, Dr. Erik Dahlquist, Dr. Jenny Palm
Dr. Erik Dahlquist
This book contains the proceedings from the Energy and IT conference at Alvsjo Energy conference "Energitinget" arranged by Swedish Energy Agency, with approximately 2500 visitors. The papers contain both technical and social science papers, relating to both energy efficiency in buildings and in industry.
New Observations Of Gas-Phase Expansion Above A Dense Non-Aqueous Phase Liquid Pool, Kevin G. Mumford, James E. Smith, Sarah E. Dickson
New Observations Of Gas-Phase Expansion Above A Dense Non-Aqueous Phase Liquid Pool, Kevin G. Mumford, James E. Smith, Sarah E. Dickson
Sarah E Dickson
The partitioning of volatile dense nonaqueous phase liquid (DNAPL) compounds to a discontinuous gas phase results in the repeated expansion, fragmentation, and vertical mobilization of gas clusters. This process has the potential to significantly affect the dissolution of DNAPL source zones and the characterization of DNAPL-contaminated sites, but has not been included in common conceptual models. This study presents new observations of discontinuous gas-phase growth above a 1,1,1-trichloroethane pool in a two-dimensional flow cell packed with 1.1-mm diameter sand. In contrast to the behavior observed in coarse glass beads, these visualization results show that the gas phase evolves as a …
Sonochemical Degradation Of Chlorinated Organic Compounds, Phenolic Compounds And Organic Dyes–A Review, Pankaj Chowdhury, T. Viraraghavan
Sonochemical Degradation Of Chlorinated Organic Compounds, Phenolic Compounds And Organic Dyes–A Review, Pankaj Chowdhury, T. Viraraghavan
PC
Sonochemical processes have been widely used in chemistry and chemical engineering field. Recently, these processes have found new applications in the environmental field, because of advantages in terms of operational simplicity, secondary pollutant formation and safety. Several studies have reported on sonochemical degradation of organic compounds that are toxic in nature. The objective of this review was to identify and examine some of the studies on sonochmical degradation of chlorinated organic compounds, phenolic compounds and organic dyes. This review also examines the basic theory of sonochemical reactions and the use of sonochemical reactors for environmental applications.
Uncontrolled Combustion Of Household Wastes And Vegetation Remains In A Rural Community – Questionnaire Results, Robert Oleniacz, Anna Tomkowicz
Uncontrolled Combustion Of Household Wastes And Vegetation Remains In A Rural Community – Questionnaire Results, Robert Oleniacz, Anna Tomkowicz
Robert Oleniacz
Uncontrolled combustion of household wastes and vegetation remains makes a serious problem referring to the emission of many substances polluting atmosphere, including polychlorinated dibenzo-p-dioxins and dibenzofurans. Combustion of post-use wastes or garbage and burning grasses are also seen as one of the causes of air pollution in larger and larger number of communities in Poland. The awareness of the Polish society referring to this problem and related appearance of different air pollutants, including dioxins and furans, has still been low. It was studied in one of Polish rural communities, based on the results of the questionnaires. In the questionnaire studies …
Computation Of Jump Coefficients For Momentum Transfer Between A Porous Medium And A Fluid Using A Closed Generalized Transfer Equation, Francisco J. Valdes-Parada, José Alvarez-Ramirez, Benoît Goyeau, J. Alberto Ochoa-Tapia
Computation Of Jump Coefficients For Momentum Transfer Between A Porous Medium And A Fluid Using A Closed Generalized Transfer Equation, Francisco J. Valdes-Parada, José Alvarez-Ramirez, Benoît Goyeau, J. Alberto Ochoa-Tapia
Francisco J. Valdes-Parada
The momentum transfer between a homogeneous fluid and a porous medium in a system analogous to the one used by Beavers and Joseph (J Fluid Mech 30:197–207, 1967) is studied using volume averaging techniques. In this article, we present a closed generalized momentum transport equation (GTE) that is valid everywhere and is expressed in terms of position-dependent effective transport coefficients, which are computed from the solution of associated closure problems previously reported. A combination of the velocity profiles from the GTE in the definition of the excess terms that define the jump coefficients allows their computation using numerical techniques. The …
Jump Condition For Diffusive And Convective Mass Transfer Between A Porous Medium And A Fluid Involving Adsorption And Chemical Reaction, Francisco J. Valdes-Parada, Jose Alvarez-Ramirez, Benoît Goyeau, J. Alberto Ochoa-Tapia
Jump Condition For Diffusive And Convective Mass Transfer Between A Porous Medium And A Fluid Involving Adsorption And Chemical Reaction, Francisco J. Valdes-Parada, Jose Alvarez-Ramirez, Benoît Goyeau, J. Alberto Ochoa-Tapia
Francisco J. Valdes-Parada
In this paper, mass transfer at the fluid–porous medium boundaries is studied.The problem considers both diffusive and convective transport, along with adsorption and reaction effects in the porous medium. The result is a mass flux jump condition that is expressed in terms of effective transport coefficients. Such coefficients (a total dispersion tensor and effective reaction and adsorption coefficients) may be computed from the solution of the corresponding closure problem here stated and solved as a function of the Péclet number (Pe), the porosity and a local Thiele modulus. For the case of negligible convective transport (i.e., Pe << 1), the closure problem reduces to the one recently solved by the authors for diffusion and reaction between a fluid and a microporous medium.
Making The Case For Community-Based Laboratories, Earthea Nance
Making The Case For Community-Based Laboratories, Earthea Nance
Earthea Nance
No abstract provided.
Influence Of Aperture Field Heterogeneity And Anisotropy On Dispersion Regimes And Dispersivity In Single Fractures, Qinghuai Zheng, Sarah E. Dickson, Yiping Guo
Influence Of Aperture Field Heterogeneity And Anisotropy On Dispersion Regimes And Dispersivity In Single Fractures, Qinghuai Zheng, Sarah E. Dickson, Yiping Guo
Sarah E Dickson
A 33 factorial experimental design was implemented to numerically investigate the interactive effect of the mean (μ b ), standard deviation (σ b ), and anisotropic ratio (AR) (λ b x /λ b y ) of single-fracture apertures on dispersion regimes (specifically Taylor dispersion and geometric dispersion) and dispersivity. The Reynolds equation was solved to obtain the flow fields in each computer-generated fracture, and the random walk particle tracking method was used to simulate solute transport. The simulation results show that (1) for a fixed hydraulic gradient, the dominant dispersion regime is controlled by μ b , and to a …
Differential Transport And Dispersion Of Colloids Relative To Solutes In Single Fractures, Qinghuai Zheng, Sarah E. Dickson, Yiping Guo
Differential Transport And Dispersion Of Colloids Relative To Solutes In Single Fractures, Qinghuai Zheng, Sarah E. Dickson, Yiping Guo
Sarah E Dickson
This work employed numerical experiments simulating colloid and solute transport in single parallelplate fractures, using the random walk particle tracking method, to demonstrate that (1) there exists an aspect ratio of the colloid radius to half the fracture aperture, do, where the average velocities of colloids and solutes are similar. When d > do, the velocity distribution assumption is satisfied, and the fact that the ratio of the colloid transport velocity to the solute transport velocity, sp, decreases as d increases is well documented in the literature. However, when d < do, the velocity distribution assumption is violated, and sp increases as d increases and (2) the Taylor dispersion coefficient and its extension by James and Chrysikopoulos [S.C. James, C. V. Chrysikopoulos, J. Colloid Interface Sci. 263 (2003) 288] will overestimate the colloid dispersion coefficient significantly. Additionally, numerical experiments simulating colloid and solute transport in variable-aperture fractures demonstrated that sp and DL,coll /DL,solute decrease with increasing CoV, and the anisotropy ratio only plays a minor role compared to the CoV. These observations have important implications towards the interpretation of colloid transport in both porous and fractured media.
Social Costs From The Use Of Cars In Cypriot Cities, Theodoros Zachariadis
Social Costs From The Use Of Cars In Cypriot Cities, Theodoros Zachariadis
Theodoros Zachariadis
No abstract provided.
Endargement Of Undeveloped Areas Of Serbia By Forest Fires, João F. Gomes
Endargement Of Undeveloped Areas Of Serbia By Forest Fires, João F. Gomes
João F Gomes
Considering the significance of discovering the causes of forest fires, the hypothesis on the solar activity is presented (i.e. physical–chemical characteristics of the solar wind) as the possible cause of these natural disasters. The empirical confirmation of the mentioned hypothesis was disabled by the non existence of an adequate data base on the (regional) distribution of the number of fires and burned areas on the level of Serbia. Therefore an emphasis is put on theoretical explanations, but also on the characteristic situations in which there is an agreement between the processes occurring on the Sun and fire phenomena in the …
2008 Report Of Crerg Research Activities, João F. Gomes
2008 Report Of Crerg Research Activities, João F. Gomes
João F Gomes
No abstract provided.
Assessment Of The Impact Of The European Co2 Emissions Trading Scheme On The Portuguese Chemical Industry, João F. Gomes
Assessment Of The Impact Of The European Co2 Emissions Trading Scheme On The Portuguese Chemical Industry, João F. Gomes
João F Gomes
No abstract provided.
Suchy System Oczyszczania Spalin Ze Spalania Odpadów Niebezpiecznych – Ocena Skuteczności Usuwania Substancji Gazowych I Możliwości Spełniania Standardów Emisyjnych, Robert Oleniacz
Robert Oleniacz
The research object was a medical waste incineration plant with a flue-gas treatment system based on dry sorption agent injection to combustion gases before a high-efficiency particulate collector. A combustion system was consisted with the fluidized bed reactor (starved air gasifier) and the secondary combustion chamber. As the dry absorbent was used a mixture of high reactive hydrated lime and activated carbon. Activated carbon content in the mixture was 5-10 % by mass. The absorbent was injected in the minimal recommended amount (4-5 kg/h). Applied collector was a ceramic filter with total filtration area of 120 m2 and guaranteed outlet …
The Development Of Humans – A Study Including Languages, Cultures, Religions And Genetics, Dr. Erik Dahlquist, Dr. Allan Dahlquist
The Development Of Humans – A Study Including Languages, Cultures, Religions And Genetics, Dr. Erik Dahlquist, Dr. Allan Dahlquist
Dr. Erik Dahlquist
The book covers the development of culture, religion, language and genetics of the human population since prehistory. Four main cultures have spread around the globe: 1) Monosyllabic language people with ancestor cult 2) Austroasiatic people with sun worshipping and megalit graves. Counting with 20 as the base 3) Uralic speaking people with kings from the sky, and strong city states. Moon and mother godess. Don´t differentiate between male and female, he and she. 4) Inflectual language speaking people with sky gods and cattles. Indoeuropeans. Often endings differentiating he and she. Shows how original cultures are refelected in todays society.
Making The Case For Community-Based Laboratories, Earthea Nance
Making The Case For Community-Based Laboratories, Earthea Nance
Earthea Nance, PhD (Stanford University, 2004)
No abstract provided.