In this paper, we used computational fluid dynamics simulation (ANSYS CFX) to compare the perform... more In this paper, we used computational fluid dynamics simulation (ANSYS CFX) to compare the performance of surfboard fins with grooves (and a bumpy-leading edge) to conventional surfboard fins. The simulations predicted the performance of each type of fins in terms of hydrodynamic forces and their behavior for angles of attack up to 45 degrees. Our results indicated that the pressure contours around fins with grooves (and bumpy-leading edge) were lower compared to pressure contours around conventional fins. The grooved fins exhibited a 13 ± 1% reduction in drag (coupled with a much smaller reduction in lift) at the stall angle, contributing to an overall 11 ± 1% improvement in the lift-to-drag ratio compared to conventional fins. Graphical abstract
The time-averaged film thickness of coating on smooth strip from a bath can be predicted by the L... more The time-averaged film thickness of coating on smooth strip from a bath can be predicted by the Landau-Levich, and Derjaguin (LLD) theory for low inertia and low Capillary number, Ca. Using the Smoothed Particle Hydrodynamics (SPH) method incorporating adhesion force of the liquid to the strip surface, cohesion between liquid particles, and robustly tuned artificial viscosity, the flow and the evolution of meniscus of liquid drag-out within Ca range 0.06 ≤ Ca ≤ 0.25 and fluid Property number P0 = 0.1 is studied to characterize the stagnation point locations and the meniscus shape. The predicted time-averaged film thicknesses match closely with the LLD prediction and previously published experimental data and other theoretical models. The distances of the stagnation points from the strip Xstg are within (2.5 ± 0.3)h∞ and insensitive to Ca. These stagnation points are always on the meniscus air-liquid interface. However, the meniscus radius and stagnation point elevation from the bath...
This paper investigates the adsorption behavior of triblock copolymer Poly (propylene oxide)-poly... more This paper investigates the adsorption behavior of triblock copolymer Poly (propylene oxide)-poly (ethylene oxide)-poly (propylene oxide), PPO-PEO-PPO on silicon and iron surfaces by using the contact angle goniometer, spectroscopic ellipsometer and atomic force microscopy (AFM). After adsorption, the decrease of water contact angle was observed on each surface; and a larger reduction of water contact angle occurred on the surface covered by the copolymer film with longer and higher weight percent of hydrophilic PEO block. This means that the PEO block may be on the top of the adsorbed copolymer film. The film thickness measurement shows that the copolymer with longer and higher weight percent of PPO block forms a thicker film on the hydrophobic surface, which suggests that the hydrophobic PPO block of the copolymer in the aqueous solution plays the main role during the adsorption of PPO-PEO-PPO onto the hydrophobic surface. It has been found from the AFM results that the roughness ...
Cool roof technology is known to reduce the cooling energy consumption of conditioned buildings d... more Cool roof technology is known to reduce the cooling energy consumption of conditioned buildings during hot periods, and widespread implementation of such roofs in a neighbourhood or precinct can mitigate the urban heat island effect. Established building energy modelling techniques are able in principle to predict the benefits of cool roofs due to reduced heat transfer through the roof structure. However, several scientific and industry publications have claimed that additional benefits can arise from the reduction in air temperature above cool roofs. Rooftop heating, ventilation and airconditioning (HVAC) equipment energy consumption would be reduced by such an effect, and the efficiency of rooftop photovoltaic (PV) panels would be improved.A small number of studies have attempted to quantify the effects of cool roofs on above-roof temperature fields and the performance of rooftop equipment, but these studies have been relatively small in scope and have produced varying results. It...
Large wind turbine structural load control: trailing edge deformation mechanism for active variab... more Large wind turbine structural load control: trailing edge deformation mechanism for active variable-camber blade
Abstract: This paper reviews different aspects of friction and asperity contacts in strip rolling... more Abstract: This paper reviews different aspects of friction and asperity contacts in strip rolling. The mixed film lubrication model considers the effect of asperity flattening and the lubrication within the working zone. The oil concentration of the emulsion at entry and throughout the roll bite is considered together with the thermal effects of the contacts. The actual area of contact due to asperity deformation can be determined from a 3-wavelength FEM model. The deformation of a randomly generated surface of the hot strip with oxide scale can also be modeled by an FEM method. The friction variation in the roll bite can be determined by a sensor roll, and the average friction determined from the forward slip by the marking method or laser Doppler method. The friction models in FEM modeling are also discussed.
ARPN journal of engineering and applied sciences, 2016
In this paper, a combined FE simulation and scratch experiments approach was used to simulate the... more In this paper, a combined FE simulation and scratch experiments approach was used to simulate the contact established between a high-speed steel (HSS) work roll and a hot strip material in hot rolling, in which the top layer and the substrate represented the HSS roll and the tip of the indenter represented a particle from oxide scale formed on the strip steel. This work focused on the contact behaviour of the oxide scale in the roll bite during hot rolling. The coefficient of friction during the simulation tests was recorded. It was found that the evolution of the coefficient of friction could be divided into two stages which are incubation period and stationary period. Associated with the evolution of the coefficient of friction, the deformation behaviour and the displacement at the cross section were characterised to study the tribological behaviour of oxide scale in contacts. The results indicated that the deformation and wear mechanism of oxide layer surface vary in different de...
Conventionally in building performance simulations (BPS), it is assumed that air entering outdoor... more Conventionally in building performance simulations (BPS), it is assumed that air entering outdoor HVAC equipment is at the outdoor ‘ambient’ temperature, obtained from a weather file. However, significant spatial variations exist in outdoor air temperature fields, especially within the thermal boundary layers that form near exposed surfaces like roofs. Experiments were conducted at three large-footprint shopping centre buildings, to characterise the above-roof temperature field. An empirical model was derived from the experimental data, and applied in BPS of a shopping centre with rooftop HVAC equipment in seven Australian climates. In these cases, the electricity savings and gas ‘penalties’ attributable to cool roofs would have been underestimated by 44–85% (61% on average) if near-roof air temperature variations had not been modelled accurately.
In this study, a dual-phase Li4Ti5O12-TiO2 microrod was successfully prepared using a modified hy... more In this study, a dual-phase Li4Ti5O12-TiO2 microrod was successfully prepared using a modified hydrothermal method and calcination process. The stoichiometry of LiOH as precursor was varied at mol ratio of 0.9, 1.1, and 1.3, to obtain the appropriate phase composition between TiO2 and Li4Ti5O12. Results show that TiO2 content has an important role in increasing the specific capacity of electrodes. The refinement of X-ray diffraction patterns by Rietveld analysis confirm that increasing the LiOH stoichiometry suppresses the TiO2 phase. In the scanning electron microscopy images, the microrod morphology was formed after calcination with diameter sizes ranging from 142.34 to 260.62 nm and microrod lengths ranging from 5.03–7.37 μm. The 0.9 LiOH sample shows a prominent electrochemical performance with the largest specific capacity of 162.72 mAh/g and 98.75% retention capacity achieved at a rate capability test of 1 C. This finding can be attributed to the appropriate amount of TiO2 tha...
This article seeks to contribute to knowledge on duct-augmented turbines by investigating the inf... more This article seeks to contribute to knowledge on duct-augmented turbines by investigating the influence of the key geometric parameters of the duct on the turbine performance: (i) duct expansion angle and length, (ii) position of the duct relative to the rotor and (iii) added geometric features to the duct. A new analytic model is proposed for the duct-augmented turbine and used for the investigation. The proposed analytic model used in this study was developed with existing momentum and blade element analysis methodologies serving as its basis. Using the proposed analytic model, the duct length is found to be more influential on the duct turbine system performance than the duct expansion angle. In addition, the performance can be enhanced by addition of a flange to the duct trailing edge. The study also highlights that the optimum rotor location within a duct is slightly behind the minimum duct area.
Purpose This paper aims to assess the adsorption behaviour and the adhesion strength of lubricant... more Purpose This paper aims to assess the adsorption behaviour and the adhesion strength of lubricant films formed by polypropylene oxide-polyethylene oxide-polypropylene oxide (PPO-PEO-PPO) with phosphate ester additive on Ti-coated surface and to identify the influence of molecular architecture and phosphate ester additive. Design/methodology/approach The thickness of the adsorbed PPO-PEO-PPO with phosphate ester lubricant films on Ti surfaces was measured by ellipsometry. The adhesion strength of the copolymer and the copolymer with phosphate ester lubricants was studied by the micro-scratch tests; the scratch tracks on the surfaces were observed by atomic force microscopy and scanning electronic microscopy. Findings The copolymer with a higher weight percentage of PPO not only formed a thicker film but also showed stronger adhesion and better lubrication performance. The added phosphate ester increased the film thickness and improved the tribological behaviour. The finding reveals t...
In recent years, the utilization of rotating parts, e.g., bearings and gears, has been continuous... more In recent years, the utilization of rotating parts, e.g., bearings and gears, has been continuously supporting the manufacturing line to produce a consistent output quality. Due to their critical role, the breakdown of these components might significantly impact the production rate. Prognosis, which is an approach that predicts the machine failure, has attracted significant interest in the last few decades. In this paper, the prognostic approaches are described briefly and advanced predictive analytics, namely a parsimonious network based on a fuzzy inference system (PANFIS), is proposed and tested for low speed slew bearing data. PANFIS differs itself from conventional prognostic approaches, supporting online lifelong prognostics without the requirement of a retraining or reconfiguration phase. The PANFIS method is applied to normal-to-failure bearing vibration data collected for 139 days to predict the time-domain features of vibration slew bearing signals. The performance of the ...
In this paper, we used computational fluid dynamics simulation (ANSYS CFX) to compare the perform... more In this paper, we used computational fluid dynamics simulation (ANSYS CFX) to compare the performance of surfboard fins with grooves (and a bumpy-leading edge) to conventional surfboard fins. The simulations predicted the performance of each type of fins in terms of hydrodynamic forces and their behavior for angles of attack up to 45 degrees. Our results indicated that the pressure contours around fins with grooves (and bumpy-leading edge) were lower compared to pressure contours around conventional fins. The grooved fins exhibited a 13 ± 1% reduction in drag (coupled with a much smaller reduction in lift) at the stall angle, contributing to an overall 11 ± 1% improvement in the lift-to-drag ratio compared to conventional fins. Graphical abstract
The time-averaged film thickness of coating on smooth strip from a bath can be predicted by the L... more The time-averaged film thickness of coating on smooth strip from a bath can be predicted by the Landau-Levich, and Derjaguin (LLD) theory for low inertia and low Capillary number, Ca. Using the Smoothed Particle Hydrodynamics (SPH) method incorporating adhesion force of the liquid to the strip surface, cohesion between liquid particles, and robustly tuned artificial viscosity, the flow and the evolution of meniscus of liquid drag-out within Ca range 0.06 ≤ Ca ≤ 0.25 and fluid Property number P0 = 0.1 is studied to characterize the stagnation point locations and the meniscus shape. The predicted time-averaged film thicknesses match closely with the LLD prediction and previously published experimental data and other theoretical models. The distances of the stagnation points from the strip Xstg are within (2.5 ± 0.3)h∞ and insensitive to Ca. These stagnation points are always on the meniscus air-liquid interface. However, the meniscus radius and stagnation point elevation from the bath...
This paper investigates the adsorption behavior of triblock copolymer Poly (propylene oxide)-poly... more This paper investigates the adsorption behavior of triblock copolymer Poly (propylene oxide)-poly (ethylene oxide)-poly (propylene oxide), PPO-PEO-PPO on silicon and iron surfaces by using the contact angle goniometer, spectroscopic ellipsometer and atomic force microscopy (AFM). After adsorption, the decrease of water contact angle was observed on each surface; and a larger reduction of water contact angle occurred on the surface covered by the copolymer film with longer and higher weight percent of hydrophilic PEO block. This means that the PEO block may be on the top of the adsorbed copolymer film. The film thickness measurement shows that the copolymer with longer and higher weight percent of PPO block forms a thicker film on the hydrophobic surface, which suggests that the hydrophobic PPO block of the copolymer in the aqueous solution plays the main role during the adsorption of PPO-PEO-PPO onto the hydrophobic surface. It has been found from the AFM results that the roughness ...
Cool roof technology is known to reduce the cooling energy consumption of conditioned buildings d... more Cool roof technology is known to reduce the cooling energy consumption of conditioned buildings during hot periods, and widespread implementation of such roofs in a neighbourhood or precinct can mitigate the urban heat island effect. Established building energy modelling techniques are able in principle to predict the benefits of cool roofs due to reduced heat transfer through the roof structure. However, several scientific and industry publications have claimed that additional benefits can arise from the reduction in air temperature above cool roofs. Rooftop heating, ventilation and airconditioning (HVAC) equipment energy consumption would be reduced by such an effect, and the efficiency of rooftop photovoltaic (PV) panels would be improved.A small number of studies have attempted to quantify the effects of cool roofs on above-roof temperature fields and the performance of rooftop equipment, but these studies have been relatively small in scope and have produced varying results. It...
Large wind turbine structural load control: trailing edge deformation mechanism for active variab... more Large wind turbine structural load control: trailing edge deformation mechanism for active variable-camber blade
Abstract: This paper reviews different aspects of friction and asperity contacts in strip rolling... more Abstract: This paper reviews different aspects of friction and asperity contacts in strip rolling. The mixed film lubrication model considers the effect of asperity flattening and the lubrication within the working zone. The oil concentration of the emulsion at entry and throughout the roll bite is considered together with the thermal effects of the contacts. The actual area of contact due to asperity deformation can be determined from a 3-wavelength FEM model. The deformation of a randomly generated surface of the hot strip with oxide scale can also be modeled by an FEM method. The friction variation in the roll bite can be determined by a sensor roll, and the average friction determined from the forward slip by the marking method or laser Doppler method. The friction models in FEM modeling are also discussed.
ARPN journal of engineering and applied sciences, 2016
In this paper, a combined FE simulation and scratch experiments approach was used to simulate the... more In this paper, a combined FE simulation and scratch experiments approach was used to simulate the contact established between a high-speed steel (HSS) work roll and a hot strip material in hot rolling, in which the top layer and the substrate represented the HSS roll and the tip of the indenter represented a particle from oxide scale formed on the strip steel. This work focused on the contact behaviour of the oxide scale in the roll bite during hot rolling. The coefficient of friction during the simulation tests was recorded. It was found that the evolution of the coefficient of friction could be divided into two stages which are incubation period and stationary period. Associated with the evolution of the coefficient of friction, the deformation behaviour and the displacement at the cross section were characterised to study the tribological behaviour of oxide scale in contacts. The results indicated that the deformation and wear mechanism of oxide layer surface vary in different de...
Conventionally in building performance simulations (BPS), it is assumed that air entering outdoor... more Conventionally in building performance simulations (BPS), it is assumed that air entering outdoor HVAC equipment is at the outdoor ‘ambient’ temperature, obtained from a weather file. However, significant spatial variations exist in outdoor air temperature fields, especially within the thermal boundary layers that form near exposed surfaces like roofs. Experiments were conducted at three large-footprint shopping centre buildings, to characterise the above-roof temperature field. An empirical model was derived from the experimental data, and applied in BPS of a shopping centre with rooftop HVAC equipment in seven Australian climates. In these cases, the electricity savings and gas ‘penalties’ attributable to cool roofs would have been underestimated by 44–85% (61% on average) if near-roof air temperature variations had not been modelled accurately.
In this study, a dual-phase Li4Ti5O12-TiO2 microrod was successfully prepared using a modified hy... more In this study, a dual-phase Li4Ti5O12-TiO2 microrod was successfully prepared using a modified hydrothermal method and calcination process. The stoichiometry of LiOH as precursor was varied at mol ratio of 0.9, 1.1, and 1.3, to obtain the appropriate phase composition between TiO2 and Li4Ti5O12. Results show that TiO2 content has an important role in increasing the specific capacity of electrodes. The refinement of X-ray diffraction patterns by Rietveld analysis confirm that increasing the LiOH stoichiometry suppresses the TiO2 phase. In the scanning electron microscopy images, the microrod morphology was formed after calcination with diameter sizes ranging from 142.34 to 260.62 nm and microrod lengths ranging from 5.03–7.37 μm. The 0.9 LiOH sample shows a prominent electrochemical performance with the largest specific capacity of 162.72 mAh/g and 98.75% retention capacity achieved at a rate capability test of 1 C. This finding can be attributed to the appropriate amount of TiO2 tha...
This article seeks to contribute to knowledge on duct-augmented turbines by investigating the inf... more This article seeks to contribute to knowledge on duct-augmented turbines by investigating the influence of the key geometric parameters of the duct on the turbine performance: (i) duct expansion angle and length, (ii) position of the duct relative to the rotor and (iii) added geometric features to the duct. A new analytic model is proposed for the duct-augmented turbine and used for the investigation. The proposed analytic model used in this study was developed with existing momentum and blade element analysis methodologies serving as its basis. Using the proposed analytic model, the duct length is found to be more influential on the duct turbine system performance than the duct expansion angle. In addition, the performance can be enhanced by addition of a flange to the duct trailing edge. The study also highlights that the optimum rotor location within a duct is slightly behind the minimum duct area.
Purpose This paper aims to assess the adsorption behaviour and the adhesion strength of lubricant... more Purpose This paper aims to assess the adsorption behaviour and the adhesion strength of lubricant films formed by polypropylene oxide-polyethylene oxide-polypropylene oxide (PPO-PEO-PPO) with phosphate ester additive on Ti-coated surface and to identify the influence of molecular architecture and phosphate ester additive. Design/methodology/approach The thickness of the adsorbed PPO-PEO-PPO with phosphate ester lubricant films on Ti surfaces was measured by ellipsometry. The adhesion strength of the copolymer and the copolymer with phosphate ester lubricants was studied by the micro-scratch tests; the scratch tracks on the surfaces were observed by atomic force microscopy and scanning electronic microscopy. Findings The copolymer with a higher weight percentage of PPO not only formed a thicker film but also showed stronger adhesion and better lubrication performance. The added phosphate ester increased the film thickness and improved the tribological behaviour. The finding reveals t...
In recent years, the utilization of rotating parts, e.g., bearings and gears, has been continuous... more In recent years, the utilization of rotating parts, e.g., bearings and gears, has been continuously supporting the manufacturing line to produce a consistent output quality. Due to their critical role, the breakdown of these components might significantly impact the production rate. Prognosis, which is an approach that predicts the machine failure, has attracted significant interest in the last few decades. In this paper, the prognostic approaches are described briefly and advanced predictive analytics, namely a parsimonious network based on a fuzzy inference system (PANFIS), is proposed and tested for low speed slew bearing data. PANFIS differs itself from conventional prognostic approaches, supporting online lifelong prognostics without the requirement of a retraining or reconfiguration phase. The PANFIS method is applied to normal-to-failure bearing vibration data collected for 139 days to predict the time-domain features of vibration slew bearing signals. The performance of the ...
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