Jason Gerhard | University of Western Ontario (original) (raw)
Papers by Jason Gerhard
Water Resources Research, 2019
Intermediate wetting pores are completely NAPL-filled upon drainage and exhibit no film drainage.... more Intermediate wetting pores are completely NAPL-filled upon drainage and exhibit no film drainage.-NAPL bypassed larger pores more frequently in intermediate wetting sand than in water wetting sand, leaving multi-pore water residual ganglia.
Journal of Hazardous Materials, 2017
Organic liquid waste (in sand) can be destroyed vis self-sustaining smoldering Under certain ... more Organic liquid waste (in sand) can be destroyed vis self-sustaining smoldering Under certain conditions the organic liquid migrates downwards into the reaction Liquid migration depends on air flow rate, system height, and liquid viscosity The migrating liquid influences, but does not penetrate, the smoldering reaction Organic liquid migration can be prevented by applying a predictable air flow rate
The time required for dense nonaqueous phase liquid (DNAPL) to cease migrating following release ... more The time required for dense nonaqueous phase liquid (DNAPL) to cease migrating following release to the subsurface is a valuable component of a site conceptual model. This study uses numerical simulation to investi-gate the migration of six different DNAPLs in sandy aquifers. The most influential parameters governing migra-tion cessation time are the density and viscosity of the DNAPL and the mean hydraulic conductivity of the aquifer. Releases of between 1 and 40 drums of chlorinated solvent DNAPLs, characterized by relatively high density and low viscosity, require on the order of months to a few years to cease migrating in a heterogeneous medium sand aquifer having an average hydraulic conductivity of 7.4 3 1023 cm/s. In contrast to this, the release of 20 drums of coal tar (qD 1061 kg/m3, lD 0.161 Pas) requires more than 100 years to cease migrating in the same aquifer. Altering the mean hydraulic conductivity of the aquifer results in a proportional change in cessa-tion times. ...
Extended Abstract Smouldering combustion, a flameless form of combustion The main objective of th... more Extended Abstract Smouldering combustion, a flameless form of combustion The main objective of this study was to model heat transfer in sand under forced air flow conditions relevant to smouldering systems. To achieve this, a new empirical correlation was developed for the volumetric heat transfer coefficient (hv) between forced air and sand at low Reynolds numbers. Nineteen experiments were conducted in a onedimensional column to evaluate the volumetric heat transfer coefficient for different air injection rates and sand particle diameters. A 1D numerical model based on local thermal non-equilibrium and Darcy flow was developed to evaluate the temperature of the solid (sand) and fluid (air) phases. The thermal properties of sand, measured with the Transient Plane Source (TPS) method (Hot Disk Thermal Constants Analyser)
International Conference of Fluid Flow, Heat and Mass Transfer
The process of diagnosing of prostate cancer using traditional methods is cumbersome because of t... more The process of diagnosing of prostate cancer using traditional methods is cumbersome because of the similarity of symptoms that are present in other diseases. Soft Computing (SC) paradigms which mimic human imprecise data manipulation and learning capabilities have been reviewed and harnessed for diagnosis and classification of prostate cancer. SC technique based on Adaptive Neuro-Fuzzy Inference System (ANFIS) facilitated symptoms analysis, diagnosis and prostate cancer classification. Age of Patient (AP), Pains in Urination (PU), Frequent Urination (FU), Blood in Semen (BS) and Pains in Pelvic (PP) served as input attributes while Prostate Risk (PR) served as output. Matrix laboratory provided the programming tools for system implementation. The practical function of the system was assessed using prostate cancer data collected from the University of Uyo Teaching Hospital. A 95% harmony observed between the computed and the expected output in the ANFIS model, showed the superiority of the ANFIS model over the fuzzy model. The system is poised to assist medical professionals in the domain of diagnosis and classification of prostate cancer for the promotion of management and treatment decisions.
There is widespread soil contamination at thousands of cites in Canada resulting from the histori... more There is widespread soil contamination at thousands of cites in Canada resulting from the historical improper storage and disposal of industrial liquids (Story et al., 2014). Large financial resources are allocated to remediation efforts due to the human and environmental health risks associated with exposure to such contamination, with over $582 million CAN spent on remediation in 2014-15 by the Canadian government alone (Treasury Board of Canada, 2016). Our scientific understanding of site remediation has evolved greatly over the past decades and it is now widely accepted that remediation of the contaminant source zone is necessary to achieve a high level of long-term remediation (Kueper et al., 2014). Non-aqueous phase liquids, or NAPLS, are one of the most prevalent contaminants at contaminated sites and are challenging to remediate due to their highly recalcitrant nature (Kueper et al., 2003). Although many remediation technologies have been developed over the past decades, the...
Eos, Transactions American Geophysical Union, 2005
A major challenge in designing resilient infrastructure is to meet the needs of sustainable devel... more A major challenge in designing resilient infrastructure is to meet the needs of sustainable development (Kennedy & Corfee-Morlot, 2013). Sustainable development requires a high degree of energy efficiency. Municipal wastewater treatment plants (WWTPs), in particular, have the potential to be much more sustainable. In the U.S., 3 – 4% of the total energy consumed is dedicated to WWTPs and drinking water services, accounting for 30 – 40% of energy consumed by municipalities (U.S. EPA, 2014). In Canada, 25% of the 123billionmunicipaldeficitin2006wastiedtowatersupplysystems(i.e.,drinkingwater,wastewater,andstormwater)(Mirza,2006).ThisproblembecomesfurthercomplicatedasmuchofNorthAmerica’sWWTPinfrastructureapproachestheendofitsdesignlife.Anestimated123 billion municipal deficit in 2006 was tied to water supply systems (i.e., drinking water, wastewater, and storm water) (Mirza, 2006). This problem becomes further complicated as much of North America’s WWTP infrastructure approaches the end of its design life. An estimated 123billionmunicipaldeficitin2006wastiedtowatersupplysystems(i.e.,drinkingwater,wastewater,andstormwater)(Mirza,2006).ThisproblembecomesfurthercomplicatedasmuchofNorthAmerica’sWWTPinfrastructureapproachestheendofitsdesignlife.Anestimated298 billion and $39 billion is required in the U.S. and Canada, respectively, to satisfactorily refurbish WWTP infrastructure (ASCE, 2013; Félio et al., 2012). Within WWTPs, around 50% of the operatin...
Waste Management
Self-sustained smouldering combustion presents strong potential as a green waste-to-energy techni... more Self-sustained smouldering combustion presents strong potential as a green waste-to-energy technique for a range of wastes, especially those with high moisture content like wastewater sewage sludge. While well-demonstrated in laboratory experiments, there is little known about scaling up this process to larger, commercial reactors. This paper addresses this knowledge gap by systematically conducting and analyzing experiments in a variety of reactors extending beyond the laboratory scale. This work reveals a robust treatment regime; however, it also identifies potential complications associated with perimeter heat losses at scale. Two key impacts, on the smouldering reactions and the air flow patterns, are shown to potentially degrade treatment if not properly understood and managed. Altogether, this study provides novel insight and guidance for scaling up smouldering science into practical, waste-to-energy systems.
International Journal of Heat and Mass Transfer
Abstract Smouldering combustion has been demonstrated to be a highly energy efficient approach to... more Abstract Smouldering combustion has been demonstrated to be a highly energy efficient approach towards waste-to-energy. The benefits of smouldering are principally due to the matching of the energy generation and transfer time scales as well as its low quenching temperature (
Combustion and Flame
Perkembangan pasar tradisional di Indonesia sangatlah pesat, fungsi pasar yang telah dibangun ole... more Perkembangan pasar tradisional di Indonesia sangatlah pesat, fungsi pasar yang telah dibangun oleh pemerintah seringkali tidak dapat maksimal untuk dimanfaatkan, hal ini mengakibatkan permasalahan pada zonasi didalamnya. Pengelompokan pasar tradisional sangatlah berperan, karena pengelompokan pasar tersebut merupakan kegiatan membagi suatu pasar menjadi kelompok-kelompok pembeli yang berbeda yang memiliki kebutuhan, karakteristik, atau perilaku yang berbeda yang mungkin membutuhkan produk atau bauran pemasaran yang berbeda. Namun masih banyak ketidaksesuaian antara zonasi yang telah dibuat oleh pengelola Pasar dengan pedagang yang menempati kios/toko/los sesuai dengan aturan yang dibuat sebelumnya. Penelitian ini merupakan penelitian hukum yuridis empiris. Jenis data penelitian terdiri dari data primer dan data sekunder yang disebut sebagai bahan hukum dengan menggunakan teknis analisis deskriptif. Tujuan dari penelitian adalah Untuk mengetahui kesadaran hukum pedagang dan faktor-faktor yang menyebabkan pedagang pasar tidak menempati los sesuai dengan zonasi di Pasar Wonokromo. Hasil penelitian menunjukkan bahwa masih rendahnya kesadaran hukum pedagang Pasar Wonokromo dimana penyebab dari pada itu adalah aspek pengetahuan, pemahaman, sikap dan perilaku pedagang yang merupakan indikator-indikator kesadaran hukum itu sendiri. Faktor usia, jenis kelamin, pendidikan terakhir, dan status kependudukan, adalah faktor-faktor yang menjadikan rendahnya indikator-indikator dari kesadaran hukum pedagang Pasar Wonokromo berkaitan dengan zonasi pengelompokan barang dagang. Pada upaya tercipta ketertiban dari tujuan zonasi pengelompokan barang itu sendiri diharapkan mulai dari pedagang maupun pihak pengelola Pasar Wonokromo mengupayakan secara maksimal penegakan aturan zonasi pengelompokan barang agar menciptakan tujuan daripada zonasi itu sendiri.
International Journal of Heat and Mass Transfer
Abstract As applied smouldering systems gain popularity for a variety of energy conversion purpos... more Abstract As applied smouldering systems gain popularity for a variety of energy conversion purposes, there is a strong interest in optimizing the reactor design to support robust smouldering. Heat losses play a critical role in the energy balance of smouldering systems, and therefore have strong implications toward understanding propagation limits and reactor design. Heat losses in an applied smouldering system were approximated by adapting the analytical model from Kuznetsov (1996), originally developed for unsteady local thermal non-equilibrium heat transfer in a porous cylinder, to simulate the cooling zone trailing the smouldering front. The analytical model was adapted to a smouldering system by solving on a domain that lengthens as the cooling zone expands at the rate of the smouldering velocity. The results are incorporated into a global energy balance on the smouldering system, thereby providing an inexpensive and rapid method to estimate the system energy efficiency. Confidence in the analytical model was provided by demonstrating its predictions compare well with existing experimental and numerical estimates of heat losses from similar smouldering systems. The model was then used to quantify the sensitivity of the heat losses to two key reactor design parameters: radius and insulation quality. The system energy efficiency was shown to be highly sensitive to improved insulation and increased radius up to ~0.1 m (i.e., laboratory-sized reactors). However, this sensitivity diminished with size. Beyond 0.4 m radius, the predicted system energy efficiency was high (~85-95%) and relatively insensitive to reactor radius and insulation quality. Therefore, commercial, batch treatment smouldering reactors do not need to be larger than 0.4 m in radius to protect against heat losses and maximize their energy efficiency. This threshold design radius is considerably less than used in current reactors and therefore can provide valuable cost savings.
Chemical Engineering Journal
It is shown that recently measured cross sections for double ionization of negative ions (H -, O ... more It is shown that recently measured cross sections for double ionization of negative ions (H -, O -, and C -) possess a universal shape when plotted in suitable dimensionless units. The shape can be represented with a simple analytical function, following the same principles as it has been done in establishing a universal shape function for single ionization [Rost and Pattard 1997 Phys. Rev. A 55 R5]. Thereby, it is demonstrated that direct double ionization dominates the cross section for the targets considered.
Water Resources Research, 2019
Intermediate wetting pores are completely NAPL-filled upon drainage and exhibit no film drainage.... more Intermediate wetting pores are completely NAPL-filled upon drainage and exhibit no film drainage.-NAPL bypassed larger pores more frequently in intermediate wetting sand than in water wetting sand, leaving multi-pore water residual ganglia.
Journal of Hazardous Materials, 2017
Organic liquid waste (in sand) can be destroyed vis self-sustaining smoldering Under certain ... more Organic liquid waste (in sand) can be destroyed vis self-sustaining smoldering Under certain conditions the organic liquid migrates downwards into the reaction Liquid migration depends on air flow rate, system height, and liquid viscosity The migrating liquid influences, but does not penetrate, the smoldering reaction Organic liquid migration can be prevented by applying a predictable air flow rate
The time required for dense nonaqueous phase liquid (DNAPL) to cease migrating following release ... more The time required for dense nonaqueous phase liquid (DNAPL) to cease migrating following release to the subsurface is a valuable component of a site conceptual model. This study uses numerical simulation to investi-gate the migration of six different DNAPLs in sandy aquifers. The most influential parameters governing migra-tion cessation time are the density and viscosity of the DNAPL and the mean hydraulic conductivity of the aquifer. Releases of between 1 and 40 drums of chlorinated solvent DNAPLs, characterized by relatively high density and low viscosity, require on the order of months to a few years to cease migrating in a heterogeneous medium sand aquifer having an average hydraulic conductivity of 7.4 3 1023 cm/s. In contrast to this, the release of 20 drums of coal tar (qD 1061 kg/m3, lD 0.161 Pas) requires more than 100 years to cease migrating in the same aquifer. Altering the mean hydraulic conductivity of the aquifer results in a proportional change in cessa-tion times. ...
Extended Abstract Smouldering combustion, a flameless form of combustion The main objective of th... more Extended Abstract Smouldering combustion, a flameless form of combustion The main objective of this study was to model heat transfer in sand under forced air flow conditions relevant to smouldering systems. To achieve this, a new empirical correlation was developed for the volumetric heat transfer coefficient (hv) between forced air and sand at low Reynolds numbers. Nineteen experiments were conducted in a onedimensional column to evaluate the volumetric heat transfer coefficient for different air injection rates and sand particle diameters. A 1D numerical model based on local thermal non-equilibrium and Darcy flow was developed to evaluate the temperature of the solid (sand) and fluid (air) phases. The thermal properties of sand, measured with the Transient Plane Source (TPS) method (Hot Disk Thermal Constants Analyser)
International Conference of Fluid Flow, Heat and Mass Transfer
The process of diagnosing of prostate cancer using traditional methods is cumbersome because of t... more The process of diagnosing of prostate cancer using traditional methods is cumbersome because of the similarity of symptoms that are present in other diseases. Soft Computing (SC) paradigms which mimic human imprecise data manipulation and learning capabilities have been reviewed and harnessed for diagnosis and classification of prostate cancer. SC technique based on Adaptive Neuro-Fuzzy Inference System (ANFIS) facilitated symptoms analysis, diagnosis and prostate cancer classification. Age of Patient (AP), Pains in Urination (PU), Frequent Urination (FU), Blood in Semen (BS) and Pains in Pelvic (PP) served as input attributes while Prostate Risk (PR) served as output. Matrix laboratory provided the programming tools for system implementation. The practical function of the system was assessed using prostate cancer data collected from the University of Uyo Teaching Hospital. A 95% harmony observed between the computed and the expected output in the ANFIS model, showed the superiority of the ANFIS model over the fuzzy model. The system is poised to assist medical professionals in the domain of diagnosis and classification of prostate cancer for the promotion of management and treatment decisions.
There is widespread soil contamination at thousands of cites in Canada resulting from the histori... more There is widespread soil contamination at thousands of cites in Canada resulting from the historical improper storage and disposal of industrial liquids (Story et al., 2014). Large financial resources are allocated to remediation efforts due to the human and environmental health risks associated with exposure to such contamination, with over $582 million CAN spent on remediation in 2014-15 by the Canadian government alone (Treasury Board of Canada, 2016). Our scientific understanding of site remediation has evolved greatly over the past decades and it is now widely accepted that remediation of the contaminant source zone is necessary to achieve a high level of long-term remediation (Kueper et al., 2014). Non-aqueous phase liquids, or NAPLS, are one of the most prevalent contaminants at contaminated sites and are challenging to remediate due to their highly recalcitrant nature (Kueper et al., 2003). Although many remediation technologies have been developed over the past decades, the...
Eos, Transactions American Geophysical Union, 2005
A major challenge in designing resilient infrastructure is to meet the needs of sustainable devel... more A major challenge in designing resilient infrastructure is to meet the needs of sustainable development (Kennedy & Corfee-Morlot, 2013). Sustainable development requires a high degree of energy efficiency. Municipal wastewater treatment plants (WWTPs), in particular, have the potential to be much more sustainable. In the U.S., 3 – 4% of the total energy consumed is dedicated to WWTPs and drinking water services, accounting for 30 – 40% of energy consumed by municipalities (U.S. EPA, 2014). In Canada, 25% of the 123billionmunicipaldeficitin2006wastiedtowatersupplysystems(i.e.,drinkingwater,wastewater,andstormwater)(Mirza,2006).ThisproblembecomesfurthercomplicatedasmuchofNorthAmerica’sWWTPinfrastructureapproachestheendofitsdesignlife.Anestimated123 billion municipal deficit in 2006 was tied to water supply systems (i.e., drinking water, wastewater, and storm water) (Mirza, 2006). This problem becomes further complicated as much of North America’s WWTP infrastructure approaches the end of its design life. An estimated 123billionmunicipaldeficitin2006wastiedtowatersupplysystems(i.e.,drinkingwater,wastewater,andstormwater)(Mirza,2006).ThisproblembecomesfurthercomplicatedasmuchofNorthAmerica’sWWTPinfrastructureapproachestheendofitsdesignlife.Anestimated298 billion and $39 billion is required in the U.S. and Canada, respectively, to satisfactorily refurbish WWTP infrastructure (ASCE, 2013; Félio et al., 2012). Within WWTPs, around 50% of the operatin...
Waste Management
Self-sustained smouldering combustion presents strong potential as a green waste-to-energy techni... more Self-sustained smouldering combustion presents strong potential as a green waste-to-energy technique for a range of wastes, especially those with high moisture content like wastewater sewage sludge. While well-demonstrated in laboratory experiments, there is little known about scaling up this process to larger, commercial reactors. This paper addresses this knowledge gap by systematically conducting and analyzing experiments in a variety of reactors extending beyond the laboratory scale. This work reveals a robust treatment regime; however, it also identifies potential complications associated with perimeter heat losses at scale. Two key impacts, on the smouldering reactions and the air flow patterns, are shown to potentially degrade treatment if not properly understood and managed. Altogether, this study provides novel insight and guidance for scaling up smouldering science into practical, waste-to-energy systems.
International Journal of Heat and Mass Transfer
Abstract Smouldering combustion has been demonstrated to be a highly energy efficient approach to... more Abstract Smouldering combustion has been demonstrated to be a highly energy efficient approach towards waste-to-energy. The benefits of smouldering are principally due to the matching of the energy generation and transfer time scales as well as its low quenching temperature (
Combustion and Flame
Perkembangan pasar tradisional di Indonesia sangatlah pesat, fungsi pasar yang telah dibangun ole... more Perkembangan pasar tradisional di Indonesia sangatlah pesat, fungsi pasar yang telah dibangun oleh pemerintah seringkali tidak dapat maksimal untuk dimanfaatkan, hal ini mengakibatkan permasalahan pada zonasi didalamnya. Pengelompokan pasar tradisional sangatlah berperan, karena pengelompokan pasar tersebut merupakan kegiatan membagi suatu pasar menjadi kelompok-kelompok pembeli yang berbeda yang memiliki kebutuhan, karakteristik, atau perilaku yang berbeda yang mungkin membutuhkan produk atau bauran pemasaran yang berbeda. Namun masih banyak ketidaksesuaian antara zonasi yang telah dibuat oleh pengelola Pasar dengan pedagang yang menempati kios/toko/los sesuai dengan aturan yang dibuat sebelumnya. Penelitian ini merupakan penelitian hukum yuridis empiris. Jenis data penelitian terdiri dari data primer dan data sekunder yang disebut sebagai bahan hukum dengan menggunakan teknis analisis deskriptif. Tujuan dari penelitian adalah Untuk mengetahui kesadaran hukum pedagang dan faktor-faktor yang menyebabkan pedagang pasar tidak menempati los sesuai dengan zonasi di Pasar Wonokromo. Hasil penelitian menunjukkan bahwa masih rendahnya kesadaran hukum pedagang Pasar Wonokromo dimana penyebab dari pada itu adalah aspek pengetahuan, pemahaman, sikap dan perilaku pedagang yang merupakan indikator-indikator kesadaran hukum itu sendiri. Faktor usia, jenis kelamin, pendidikan terakhir, dan status kependudukan, adalah faktor-faktor yang menjadikan rendahnya indikator-indikator dari kesadaran hukum pedagang Pasar Wonokromo berkaitan dengan zonasi pengelompokan barang dagang. Pada upaya tercipta ketertiban dari tujuan zonasi pengelompokan barang itu sendiri diharapkan mulai dari pedagang maupun pihak pengelola Pasar Wonokromo mengupayakan secara maksimal penegakan aturan zonasi pengelompokan barang agar menciptakan tujuan daripada zonasi itu sendiri.
International Journal of Heat and Mass Transfer
Abstract As applied smouldering systems gain popularity for a variety of energy conversion purpos... more Abstract As applied smouldering systems gain popularity for a variety of energy conversion purposes, there is a strong interest in optimizing the reactor design to support robust smouldering. Heat losses play a critical role in the energy balance of smouldering systems, and therefore have strong implications toward understanding propagation limits and reactor design. Heat losses in an applied smouldering system were approximated by adapting the analytical model from Kuznetsov (1996), originally developed for unsteady local thermal non-equilibrium heat transfer in a porous cylinder, to simulate the cooling zone trailing the smouldering front. The analytical model was adapted to a smouldering system by solving on a domain that lengthens as the cooling zone expands at the rate of the smouldering velocity. The results are incorporated into a global energy balance on the smouldering system, thereby providing an inexpensive and rapid method to estimate the system energy efficiency. Confidence in the analytical model was provided by demonstrating its predictions compare well with existing experimental and numerical estimates of heat losses from similar smouldering systems. The model was then used to quantify the sensitivity of the heat losses to two key reactor design parameters: radius and insulation quality. The system energy efficiency was shown to be highly sensitive to improved insulation and increased radius up to ~0.1 m (i.e., laboratory-sized reactors). However, this sensitivity diminished with size. Beyond 0.4 m radius, the predicted system energy efficiency was high (~85-95%) and relatively insensitive to reactor radius and insulation quality. Therefore, commercial, batch treatment smouldering reactors do not need to be larger than 0.4 m in radius to protect against heat losses and maximize their energy efficiency. This threshold design radius is considerably less than used in current reactors and therefore can provide valuable cost savings.
Chemical Engineering Journal
It is shown that recently measured cross sections for double ionization of negative ions (H -, O ... more It is shown that recently measured cross sections for double ionization of negative ions (H -, O -, and C -) possess a universal shape when plotted in suitable dimensionless units. The shape can be represented with a simple analytical function, following the same principles as it has been done in establishing a universal shape function for single ionization [Rost and Pattard 1997 Phys. Rev. A 55 R5]. Thereby, it is demonstrated that direct double ionization dominates the cross section for the targets considered.