Wind loads on solar panels mounted parallel to pitched roofs, and acting on the underlying roof

Leitch, C.J.,Ginger, J.D.,Holmes, J.D. Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.22 No.3

This paper describes an investigation of the net wind loads on solar panels and wind loads on the underlying roof surface for panels mounted parallel to pitched roofs of domestic buildings. Typical solar panel array configurations were studied in a wind tunnel and the aerodynamic shape factors on the panels were put in a form appropriate for the Australian/New Zealand Wind Actions Standard AS/NZS 1170.2:2011. The results can also be used to obtain more refined design data on individual panels within an array. They also suggest values for the aerodynamic shape factors on the roof surface under the panels, based on a gust wind speed at roof height, of ${\pm}0.5$ for wind blowing parallel to the ridge, and ${\pm}0.6$ for wind blowing perpendicular to the ridge. The net loads on solar arrays in the middle portion of the roof are larger than those on the same portion of the roof without any solar panels, thus resulting in increased loads on the underlying roof structure.

Interdisciplinary semantic model for managing the design of a steam-assisted gravity drainage tooling system

Leitch, Michael,Yusuf, Yishak,Ma, Yongsheng Society for Computational Design and Engineering 2018 Journal of computational design and engineering Vol.5 No.1

Complex engineering systems often require extensive coordination between different expert areas in order to avoid costly design iterations and rework. Cyber-physics system (CPS) engineering methods could provide valuable insights to help model these interactions and optimize the design of such systems. In this work, steam assisted gravity drainage (SAGD), a complex oil extraction process that requires deep understanding of several physical-chemical phenomena, is examined whereby the complexities and interdependencies of the system are explored. Based on an established unified feature modeling scheme, a software modeling framework is proposed to manage the design process of the production tools used for SAGD oil extraction. Applying CPS methods to unify complex phenomenon and engineering models, the proposed CPS model combines effective simulation with embedded knowledge of completion tooling design in order to optimize reservoir performance. The system design is expressed using graphical diagrams of the unified modelling language (UML) convention. To demonstrate the capability of this system, a distributed research group is described, and their activities coordinated using the described CPS model.

Interdisciplinary semantic model for managing the design of a steam-assisted gravity drainage tooling system

Michael Leitch,Yishak Yusuf,Yongsheng Ma 한국CDE학회 2018 Journal of computational design and engineering Vol.5 No.1

Complex engineering systems often require extensive coordination between different expert areas in order to avoid costly design iterations and rework. Cyber-physics system (CPS) engineering methods could provide valuable insights to help model these interactions and optimize the design of such systems. In this work, steam assisted gravity drainage (SAGD), a complex oil extraction process that requires deep understanding of several physical-chemical phenomena, is examined whereby the complexities and interdependencies of the system are explored. Based on an established unified feature modeling scheme, a software modeling framework is proposed to manage the design process of the production tools used for SAGD oil extraction. Applying CPS methods to unify complex phenomenon and engineering models, the proposed CPS model combines effective simulation with embedded knowledge of completion tooling design in order to optimize reservoir performance. The system design is expressed using graphical diagrams of the unified modelling language (UML) convention. To demonstrate the capability of this system, a distributed research group is described, and their activities coordinated using the described CPS model.

Wind loads on solar panels mounted parallel to pitched roofs, and acting on the underlying roof

C.J. Leitch,J. D. Ginger,J.D. Holmes 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.22 No.3

This paper describes an investigation of the net wind loads on solar panels and wind loads on the underlying roof surface for panels mounted parallel to pitched roofs of domestic buildings. Typical solar panel array configurations were studied in a wind tunnel and the aerodynamic shape factors on the panels were put in a form appropriate for the Australian/New Zealand Wind Actions Standard AS/NZS 1170.2:2011. The results can also be used to obtain more refined design data on individual panels within an array. They also suggest values for the aerodynamic shape factors on the roof surface under the panels, based on a gust wind speed at roof height, of 0.5 for wind blowing parallel to the ridge, and 0.6 for wind blowing perpendicular to the ridge. The net loads on solar arrays in the middle portion of the roof are larger than those on the same portion of the roof without any solar panels, thus resulting in increased loads on the underlying roof structure.

Synthesis of phenolic resol resins using cornstalk-derived bio-oil produced by direct liquefaction in hot-compressed phenol–water

Mingcun Wang,Mathew Leitch,Chunbao Charles Xu 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.6

For the synthesis of biomass-based resol resins, cornstalk powders were liquefied in a hot-compressed phenol–water (1:4, wt./wt.) medium at 300–350 8C. It was observed that essentially no phenol was reacted with the cornstalk degradation intermediates during the liquefaction process. The cornstalkderived bio-oils contained oligomers of phenol and substituted phenols, originated primarily from the lignin component of the cornstalk feedstock. Using the cornstalk-derived bio-oils, resol resins were readily synthesized under the catalysis of sodium hydroxide. The biomass-derived resol resins were brown viscous liquids, possessing broad molecular weight distributions. In comparison with those of a conventional phenol resol resin, the properties of the bio-based resins were characterized by GPC, FTIR, DSC and TGA. The as-synthesized bio-oil resol resin exhibited typical properties of a thermosetting phenol–formaldehyde resin, e.g., exothermic curing temperatures at about 150–160℃, and an acceptable residual carbon yield of ca 56% at 700℃ for the cured material.

A MICROSTRUCTURAL MODEL OF THE THERMAL CONDUCTIVITY OF DISPERSION TYPE FUELS WITH A FUEL MATRIX INTERACTION LAYER

Williams, A.F.,Leitch, B.W.,Wang, N. Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.7

This paper describes a finite element model of the microstructure of dispersion type nuclear fuels, which can be used to determine the effective thermal conductivity of the fuels during irradiation. The model simulates a representative region of the fuel as a prism shaped unit cell made of brick elements. The elements within the unit cell are assigned material properties of either the fuel or the matrix depending on position, in such a way as to represent randomly distributed fuel particles with a size distribution similar to that of the as manufactured fuel. By applying an appropriate heat flux across the unit cell it is possible to determine the effective thermal conductivity of the unit cell as a function of the volume fraction of the fuel particles. The presence of a fuel/matrix interaction layer is simulated by the addition of a third set of material properties that are assigned to the finite elements that surround each fuel particle. In this way the effective thermal conductivity of the material may also be determined as a function of the volume fraction of the interaction layer. Work is on going to add fission gas bubbles in the fuel as a fourth phase to the model.

A Microstructural Model of the Thermal Conductivity of Dispersion Type Fuels with a Fuel Matrix Interaction Layer

A.F. Williams,B.W. Leitch,N. Wang 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.7

This paper describes a finite element model of the microstructure of dispersion type nuclear fuels, which can be used todetermine the effective thermal conductivity of the fuels during irradiation. The model simulates a representative region of thefuel as a prism shaped unit cell made of brick elements. The elements within the unit cell are assigned material properties ofeither the fuel or the matrix depending on position, in such a way as to represent randomly distributed fuel particles with a sizedistribution similar to that of the as manufactured fuel. By applying an appropriate heat flux across the unit cell it is possible todetermine the effective thermal conductivity of the unit cell as a function of the volume fraction of the fuel particles. Thepresence of a fuel/matrix interaction layer is simulated by the addition of a third set of material properties that are assigned tothe finite elements that surround each fuel particle. In this way the effective thermal conductivity of the material may also bedetermined as a function of the volume fraction of the interaction layer. Work is on going to add fission gas bubbles in the fuelas a fourth phase to the model.

Aspirin Use Is Associated With Improved Outcomes in Inflammatory Breast Cancer Patients

Christopher Johns,Allen Yen,Asal Rahimi,Yu-Lun Liu,Ann Marilyn Leitch,Ann Spangler,Prasanna Alluri,Chika Nwachukwu,Rachel Wooldridge,Deborah Farr,D. W. Nathan Kim 한국유방암학회 2023 Journal of breast cancer Vol.26 No.1

Purpose: Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer and has a high propensity for distant metastases. Our previous data suggested that aspirin (acetylsalicylic acid, ASA) use may be associated with reduced risk of distant metastases in aggressive breast cancer; however, there are no reported studies on the potential benefit of ASA use in patients with IBC. Methods: Data from patients with non-metastatic IBC treated between 2000–2017 at two institutions, were reviewed. Overall survival (OS), disease-free survival (DFS), and distant metastasis-free survival (DMFS) were performed using Kaplan-Meier analysis. Univariate and multivariable logistic regression models were used to identify significant associated factors. Results: Of 59 patients meeting the criteria for analysis and available for review, 14 ASA users were identified. ASA users demonstrated increased OS (p = 0.03) and DMFS (p = 0.02), with 5-year OS and DMFS of 92% (p = 0.01) and 85% (p = 0.01) compared to 51% and 43%, respectively, for non-ASA users. In univariate analysis, pT stage, pN stage, and ASA use were significantly correlated (p < 0.05) with OS and DFS. On multivariable analysis, ASA use (hazard ratio [HR], 0.11; 95% confidence interval [CI], 0.01–0.8) and lymph node stage (HR, 5.9; 95% CI, 1.4–25.9) remained significant for OS and DFS ASA use (HR, 0.13; 95% CI, 0.03–0.56) and lymph node stage (HR, 5.6; 95% CI, 1.9–16.4). Conclusion: ASA use during remission was associated with significantly improved OS and DMFS in patients with IBC. These results suggest that ASA may provide survival benefits to patients with IBC. Prospective clinical trials of ASA use in patients with high-risk IBC in remission should be considered.