Laurent Pilon | University of California, Los Angeles (original) (raw)

Papers by Laurent Pilon

Research paper thumbnail of Comparison of experimentally and theoretically determined radiation characteristics of photosynthetic microorganisms

Journal of Quantitative Spectroscopy and Radiative Transfer, 2016

Research paper thumbnail of Superficial Gas Velocity for Onset of Foaming

Chemical Engineering and Processing, 2004

Research paper thumbnail of Effect of surface hydroxyl groups on heat capacity of mesoporous silica

Research paper thumbnail of Three-Dimensional Flow and Thermal Structure in Glass Melting Furnaces. Part I: Effect of the Net Heat Flux Distribution

Glass Science and Technology, 2002

Research paper thumbnail of Three-Dimensional Flow and Thermal Structure in Glass Melting Furnaces. Part II: Effect of Batch and Bubbles

Glass Science and Technology, 2002

Research paper thumbnail of Radiation characteristics of Botryococcus braunii, Chlorococcum littorale, and Chlorella sp. used for CO 2 fixation and biofuel production

J Quant Spectrosc Radiat, 2009

Research paper thumbnail of Modified Method of Characteristics for Transient Radiative Transfer

Journal of Quantitative Spectroscopy and Radiative Transfer, 2006

Research paper thumbnail of Scaling Analysis of Thermal Behavior of Electrical Double Layers

Volume 1: Heat Transfer in Energy Systems; Theory and Fundamental Research; Aerospace Heat Transfer; Gas Turbine Heat Transfer; Transport Phenomena in Materials Processing and Manufacturing; Heat and, 2012

Research paper thumbnail of Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors

Journal of the Electrochemical Society, 2015

Research paper thumbnail of Annual energy analysis of concrete containing phase change materials for building envelopes

Energy Conversion and Management, 2015

Research paper thumbnail of Radiation Characteristics of Promising Algae for CO

Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Heat Transfer Equipment; Heat Transfer in Electronic Equipment, 2009

Research paper thumbnail of Symbiotic Cultures for Increasing the Solar Energy Conversion Efficiency of Outdoor Photobioreactors

Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Heat Transfer Equipment; Heat Transfer in Electronic Equipment, 2009

ABSTRACT A numerical study is presented aiming to maximize the solar to hydrogen energy conversio... more ABSTRACT A numerical study is presented aiming to maximize the solar to hydrogen energy conversion efficiency of a symbiotic culture containing microorganisms with different absorption characteristics. The green algae Chlamydomonas reinhardtii CC125 and the purple non-sulfur bacteria Rhodobacter sphearoides ATCC 49419 are chosen for illustration purposes. The previously measured radiation characteristics of each microorganism are used as input parameters in the radiative transport equation for calculating the local spectral incident radiation within a flat panel photobioreactor. The specific hydrogen production rate for each microorganism as a function of the available incident radiation is recovered from data reported in the literature. The overall solar to hydrogen energy conversion efficiency of symbiotic cultures of varying microorganism concentrations have been computed for photobioreactor thicknesses from 1 to 10 cm. The results show that for a given photobioreactor thickness a saturation microorganism concentration exists above which the solar energy conversion efficiency does not increase. The maximum solar energy conversion efficiencies of solo cultures of C. reinhardtii and R. spaheroides at their respective saturation concentrations are 0.06 and 0.055%, respectively. Using symbiotic cultures, a total conversion efficiency of about 0.075% is achieved within the parameter range explored. It has been shown that the choice of microorganism concentrations for maximum solar energy conversion efficiency is non-trivial and requires careful radiation transfer analysis coupled with H2 production kinetics taking into account the photobioreactor thickness. The presented numerical tool can be used for simulating any photobiological or photochemical process involving more than one species with different radiation characteristics provided the closure laws for the reaction kinetics are known as a function of spectral incident radiation. Examples include (i) the symbiotic cultivation of more than one microorganism for biomass or lipid production in a photobioreactor and (ii) a photochemical reactor containing a number of absorbing and scattering photocatalysts with different band gaps.

Research paper thumbnail of Optimum Operation of a Prototypical Pyroelectric Energy Converter for Harvesting Waste Heat

Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability, 2007

A 2-D numerical model was proposed to investigate the ignition of liquid fuel droplets in convect... more A 2-D numerical model was proposed to investigate the ignition of liquid fuel droplets in convective environments at high temperature. This model employed a skeletal mechanism consisting of 34 reactive species and 56 elementary reactions, rather than one-step overall reaction as in normal 2-D droplet ignition models, because the skeletal mechanism for n-heptane reproduces ignition delay times at various temperatures and pressures reasonably well. In present investigation an emphasis was addressed on the comparative analysis of suitability of the model, particularly numerical simulations were compared with experiments available in the literature, or for N-heptane droplets ignition in the convective air at temperature in a range of 1100K∼1400K and velocity of 2m/s. The ignition delay time and ignition position were obtained using an ignition criterion based on OH radical mass fraction. The flame behavior after ignition was also studied comparatively. The agreement between numerical si...

Research paper thumbnail of Thermal Conductivity of Sol-Gel Amorphous Mesoporous Silica Thin Films: Molecular Dynamics Simulations Versus Experiments

ASME/JSME 2011 8th Thermal Engineering Joint Conference, 2011

ABSTRACT This study reports non-equilibrium molecular dynamics (MD) simulations predicting the th... more ABSTRACT This study reports non-equilibrium molecular dynamics (MD) simulations predicting the thermal conductivity of amorphous mesoporous silica. The heat flux was imposed using the Muller-Plathe method and interatomic interactions were modeled using the van Beest, Kramer and van Santen (BKS) potential. First, simulations were validated against results reported in the literature for dense quartz and amorphous silica. The BKS potential was found to significantly overestimate the thermal conductivity of dense amorphous silica and results depended on the length of the simulation cell. Then, highly ordered pores were introduced in an amorphous silica matrix by removing atoms within selected areas of the simulation cell. Effects of the simulation cell length, pore size, and porosity on the thermal conductivity were investigated at room temperature. Results were compared with predictions from commonly used effective medium approximations as well as with previously reported experimental data for films with porosity and pore diameter ranging from 20% to 48% and 30 to 180 Å, respectively. Predictions of MD simulations overestimated the experimental data and agreed with predictions from the coherent potential model. However, MD simulations confirmed that thermal conductivity in sol-gel amorphous mesoporous materials was independent of pore size and depended only on porosity.

Research paper thumbnail of Flow and Heat Transfer of Microfoams in Horizontal Minichannels

Heat Transfer, Volume 2, 2004

Research paper thumbnail of Thermal Conductivity of Ordered Mesoporous Silicon Thin Films Made From Magnesium Reduction of Polymer Templated Silica

Volume 10: Heat and Mass Transport Processes, Parts A and B, 2011

Research paper thumbnail of Bubble transport in three-dimensional gravity driven flow, part i. Mathematical formulation

Journal of Non- …, 2004

Permalink: http://escholarship.org/uc/item/9r04z57r ... Additional Info: The published version of... more Permalink: http://escholarship.org/uc/item/9r04z57r ... Additional Info: The published version of this article is available at: www.elsevier.com/locate/jnoncrysol ... Original Citation: L. Pilon, AG Fedorov, D. Ramkrishna, and R. Viskanta, 2004. Bubble Transport in Three- ...

Research paper thumbnail of Foot Technology, Part 2 of 2: Hyperspectral Imaging in Diabetic Foot Wound Care

Journal of Diabetes Science and Technology, Sep 1, 2010

Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of... more Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of type 1 and 2 diabetes patients during their lifetime. If untreated, diabetic foot ulcers may become infected and require total or partial amputation of the affected limb. Early identification of tissue at risk of ulcerating could enable proper preventive care, thereby reducing the incidence of foot ulceration. Furthermore, noninvasive assessment of tissue viability around already formed ulcers could inform the diabetes caregiver about the severity of the wound and help assess the need for amputation. This article reviews how hyperspectral imaging between 450 and 700 nm can be used to assess the risk of diabetic foot ulcer development and to predict the likelihood of healing noninvasively. Two methods are described to analyze the in vivo hyperspectral measurements. The first method is based on the modified Beer-Lambert law and produces a map of oxyhemoglobin and deoxyhemoglobin concentrations in the dermis of the foot. The second is based on a two-layer optical model of skin and can retrieve not only oxyhemoglobin and deoxyhemoglobin concentrations but also epidermal thickness and melanin concentration along with skin scattering properties. It can detect changes in the diabetic foot and help predict and understand ulceration mechanisms.

Research paper thumbnail of Foot Technology, Part 2 of 2: Hyperspectral Imaging in Diabetic Foot Wound Care

Journal of Diabetes Science and Technology, Sep 1, 2010

Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of... more Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of type 1 and 2 diabetes patients during their lifetime. If untreated, diabetic foot ulcers may become infected and require total or partial amputation of the affected limb. Early identification of tissue at risk of ulcerating could enable proper preventive care, thereby reducing the incidence of foot ulceration. Furthermore, noninvasive assessment of tissue viability around already formed ulcers could inform the diabetes caregiver about the severity of the wound and help assess the need for amputation. This article reviews how hyperspectral imaging between 450 and 700 nm can be used to assess the risk of diabetic foot ulcer development and to predict the likelihood of healing noninvasively. Two methods are described to analyze the in vivo hyperspectral measurements. The first method is based on the modified Beer-Lambert law and produces a map of oxyhemoglobin and deoxyhemoglobin concentrations in the dermis of the foot. The second is based on a two-layer optical model of skin and can retrieve not only oxyhemoglobin and deoxyhemoglobin concentrations but also epidermal thickness and melanin concentration along with skin scattering properties. It can detect changes in the diabetic foot and help predict and understand ulceration mechanisms.

Research paper thumbnail of Use of Mie theory to analyze experimental data to identify infrared properties of fused quartz containing bubbles

Research paper thumbnail of Comparison of experimentally and theoretically determined radiation characteristics of photosynthetic microorganisms

Journal of Quantitative Spectroscopy and Radiative Transfer, 2016

Research paper thumbnail of Superficial Gas Velocity for Onset of Foaming

Chemical Engineering and Processing, 2004

Research paper thumbnail of Effect of surface hydroxyl groups on heat capacity of mesoporous silica

Research paper thumbnail of Three-Dimensional Flow and Thermal Structure in Glass Melting Furnaces. Part I: Effect of the Net Heat Flux Distribution

Glass Science and Technology, 2002

Research paper thumbnail of Three-Dimensional Flow and Thermal Structure in Glass Melting Furnaces. Part II: Effect of Batch and Bubbles

Glass Science and Technology, 2002

Research paper thumbnail of Radiation characteristics of Botryococcus braunii, Chlorococcum littorale, and Chlorella sp. used for CO 2 fixation and biofuel production

J Quant Spectrosc Radiat, 2009

Research paper thumbnail of Modified Method of Characteristics for Transient Radiative Transfer

Journal of Quantitative Spectroscopy and Radiative Transfer, 2006

Research paper thumbnail of Scaling Analysis of Thermal Behavior of Electrical Double Layers

Volume 1: Heat Transfer in Energy Systems; Theory and Fundamental Research; Aerospace Heat Transfer; Gas Turbine Heat Transfer; Transport Phenomena in Materials Processing and Manufacturing; Heat and, 2012

Research paper thumbnail of Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors

Journal of the Electrochemical Society, 2015

Research paper thumbnail of Annual energy analysis of concrete containing phase change materials for building envelopes

Energy Conversion and Management, 2015

Research paper thumbnail of Radiation Characteristics of Promising Algae for CO

Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Heat Transfer Equipment; Heat Transfer in Electronic Equipment, 2009

Research paper thumbnail of Symbiotic Cultures for Increasing the Solar Energy Conversion Efficiency of Outdoor Photobioreactors

Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Heat Transfer Equipment; Heat Transfer in Electronic Equipment, 2009

ABSTRACT A numerical study is presented aiming to maximize the solar to hydrogen energy conversio... more ABSTRACT A numerical study is presented aiming to maximize the solar to hydrogen energy conversion efficiency of a symbiotic culture containing microorganisms with different absorption characteristics. The green algae Chlamydomonas reinhardtii CC125 and the purple non-sulfur bacteria Rhodobacter sphearoides ATCC 49419 are chosen for illustration purposes. The previously measured radiation characteristics of each microorganism are used as input parameters in the radiative transport equation for calculating the local spectral incident radiation within a flat panel photobioreactor. The specific hydrogen production rate for each microorganism as a function of the available incident radiation is recovered from data reported in the literature. The overall solar to hydrogen energy conversion efficiency of symbiotic cultures of varying microorganism concentrations have been computed for photobioreactor thicknesses from 1 to 10 cm. The results show that for a given photobioreactor thickness a saturation microorganism concentration exists above which the solar energy conversion efficiency does not increase. The maximum solar energy conversion efficiencies of solo cultures of C. reinhardtii and R. spaheroides at their respective saturation concentrations are 0.06 and 0.055%, respectively. Using symbiotic cultures, a total conversion efficiency of about 0.075% is achieved within the parameter range explored. It has been shown that the choice of microorganism concentrations for maximum solar energy conversion efficiency is non-trivial and requires careful radiation transfer analysis coupled with H2 production kinetics taking into account the photobioreactor thickness. The presented numerical tool can be used for simulating any photobiological or photochemical process involving more than one species with different radiation characteristics provided the closure laws for the reaction kinetics are known as a function of spectral incident radiation. Examples include (i) the symbiotic cultivation of more than one microorganism for biomass or lipid production in a photobioreactor and (ii) a photochemical reactor containing a number of absorbing and scattering photocatalysts with different band gaps.

Research paper thumbnail of Optimum Operation of a Prototypical Pyroelectric Energy Converter for Harvesting Waste Heat

Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability, 2007

A 2-D numerical model was proposed to investigate the ignition of liquid fuel droplets in convect... more A 2-D numerical model was proposed to investigate the ignition of liquid fuel droplets in convective environments at high temperature. This model employed a skeletal mechanism consisting of 34 reactive species and 56 elementary reactions, rather than one-step overall reaction as in normal 2-D droplet ignition models, because the skeletal mechanism for n-heptane reproduces ignition delay times at various temperatures and pressures reasonably well. In present investigation an emphasis was addressed on the comparative analysis of suitability of the model, particularly numerical simulations were compared with experiments available in the literature, or for N-heptane droplets ignition in the convective air at temperature in a range of 1100K∼1400K and velocity of 2m/s. The ignition delay time and ignition position were obtained using an ignition criterion based on OH radical mass fraction. The flame behavior after ignition was also studied comparatively. The agreement between numerical si...

Research paper thumbnail of Thermal Conductivity of Sol-Gel Amorphous Mesoporous Silica Thin Films: Molecular Dynamics Simulations Versus Experiments

ASME/JSME 2011 8th Thermal Engineering Joint Conference, 2011

ABSTRACT This study reports non-equilibrium molecular dynamics (MD) simulations predicting the th... more ABSTRACT This study reports non-equilibrium molecular dynamics (MD) simulations predicting the thermal conductivity of amorphous mesoporous silica. The heat flux was imposed using the Muller-Plathe method and interatomic interactions were modeled using the van Beest, Kramer and van Santen (BKS) potential. First, simulations were validated against results reported in the literature for dense quartz and amorphous silica. The BKS potential was found to significantly overestimate the thermal conductivity of dense amorphous silica and results depended on the length of the simulation cell. Then, highly ordered pores were introduced in an amorphous silica matrix by removing atoms within selected areas of the simulation cell. Effects of the simulation cell length, pore size, and porosity on the thermal conductivity were investigated at room temperature. Results were compared with predictions from commonly used effective medium approximations as well as with previously reported experimental data for films with porosity and pore diameter ranging from 20% to 48% and 30 to 180 Å, respectively. Predictions of MD simulations overestimated the experimental data and agreed with predictions from the coherent potential model. However, MD simulations confirmed that thermal conductivity in sol-gel amorphous mesoporous materials was independent of pore size and depended only on porosity.

Research paper thumbnail of Flow and Heat Transfer of Microfoams in Horizontal Minichannels

Heat Transfer, Volume 2, 2004

Research paper thumbnail of Thermal Conductivity of Ordered Mesoporous Silicon Thin Films Made From Magnesium Reduction of Polymer Templated Silica

Volume 10: Heat and Mass Transport Processes, Parts A and B, 2011

Research paper thumbnail of Bubble transport in three-dimensional gravity driven flow, part i. Mathematical formulation

Journal of Non- …, 2004

Permalink: http://escholarship.org/uc/item/9r04z57r ... Additional Info: The published version of... more Permalink: http://escholarship.org/uc/item/9r04z57r ... Additional Info: The published version of this article is available at: www.elsevier.com/locate/jnoncrysol ... Original Citation: L. Pilon, AG Fedorov, D. Ramkrishna, and R. Viskanta, 2004. Bubble Transport in Three- ...

Research paper thumbnail of Foot Technology, Part 2 of 2: Hyperspectral Imaging in Diabetic Foot Wound Care

Journal of Diabetes Science and Technology, Sep 1, 2010

Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of... more Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of type 1 and 2 diabetes patients during their lifetime. If untreated, diabetic foot ulcers may become infected and require total or partial amputation of the affected limb. Early identification of tissue at risk of ulcerating could enable proper preventive care, thereby reducing the incidence of foot ulceration. Furthermore, noninvasive assessment of tissue viability around already formed ulcers could inform the diabetes caregiver about the severity of the wound and help assess the need for amputation. This article reviews how hyperspectral imaging between 450 and 700 nm can be used to assess the risk of diabetic foot ulcer development and to predict the likelihood of healing noninvasively. Two methods are described to analyze the in vivo hyperspectral measurements. The first method is based on the modified Beer-Lambert law and produces a map of oxyhemoglobin and deoxyhemoglobin concentrations in the dermis of the foot. The second is based on a two-layer optical model of skin and can retrieve not only oxyhemoglobin and deoxyhemoglobin concentrations but also epidermal thickness and melanin concentration along with skin scattering properties. It can detect changes in the diabetic foot and help predict and understand ulceration mechanisms.

Research paper thumbnail of Foot Technology, Part 2 of 2: Hyperspectral Imaging in Diabetic Foot Wound Care

Journal of Diabetes Science and Technology, Sep 1, 2010

Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of... more Diabetic foot ulceration is a major complication of diabetes and afflicts as many as 15 to 25% of type 1 and 2 diabetes patients during their lifetime. If untreated, diabetic foot ulcers may become infected and require total or partial amputation of the affected limb. Early identification of tissue at risk of ulcerating could enable proper preventive care, thereby reducing the incidence of foot ulceration. Furthermore, noninvasive assessment of tissue viability around already formed ulcers could inform the diabetes caregiver about the severity of the wound and help assess the need for amputation. This article reviews how hyperspectral imaging between 450 and 700 nm can be used to assess the risk of diabetic foot ulcer development and to predict the likelihood of healing noninvasively. Two methods are described to analyze the in vivo hyperspectral measurements. The first method is based on the modified Beer-Lambert law and produces a map of oxyhemoglobin and deoxyhemoglobin concentrations in the dermis of the foot. The second is based on a two-layer optical model of skin and can retrieve not only oxyhemoglobin and deoxyhemoglobin concentrations but also epidermal thickness and melanin concentration along with skin scattering properties. It can detect changes in the diabetic foot and help predict and understand ulceration mechanisms.

Research paper thumbnail of Use of Mie theory to analyze experimental data to identify infrared properties of fused quartz containing bubbles