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Renewable energy sources prevail as a clean energy source and their penetration in the power sector is increasing day by day due to the growing concern for climate action. However, the intermittent nature of the renewable energy based-power generation questions the grid security, especially when the utilized source is solar radiation or wind flow. The intermittency of the renewable generation can be met by the integration of distributed energy resources. The virtual power plant (VPP) is a new concept which aggregates the capacities of various distributed energy resources, handles controllable and uncontrollable loads, integrates storage devices and empowers participation as an individual power plant in the electricity market. The VPP as an energy management system (EMS) should optimally dispatch the power to its consumers. This research work is proposed to analyze the optimal scheduling of generation in VPP for the day-ahead market framework using the beetle antenna search (BAS) algorithm under various scenarios. A case study is considered for this analysis in which the constituting energy resources include a photovoltaic solar panel (PV), micro-turbine (MT), wind turbine (WT), fuel cell (FC), battery energy storage system (BESS) and controllable loads. The real-time hourly load curves are considered in this work. Three different scenarios are considered for the optimal dispatch of generation in the VPP to analyze the performance of the proposed technique. The uncertainties of the solar irradiation and the wind speed are modeled using the beta distribution method and Weibull distribution method, respectively. The performance of the proposed method is compared with other evolutionary algorithms such as particle swarm optimization (PSO) and the genetic algorithm (GA). Among these above-mentioned algorithms, the proposed BAS algorithm shows the best scheduling with the minimum operating cost of generation.
Poushali Pal; Parvathy Krishnamoorthy; Devabalaji Rukmani; S. Antony; Simon Ocheme; Umashankar Subramanian; Rajvikram Elavarasan; Narottam Das; Hany Hasanien. Optimal Dispatch Strategy of Virtual Power Plant for Day-Ahead Market Framework. Applied Sciences 2021, 11, 3814 .
AMA StylePoushali Pal, Parvathy Krishnamoorthy, Devabalaji Rukmani, S. Antony, Simon Ocheme, Umashankar Subramanian, Rajvikram Elavarasan, Narottam Das, Hany Hasanien. Optimal Dispatch Strategy of Virtual Power Plant for Day-Ahead Market Framework. Applied Sciences. 2021; 11 (9):3814.
Chicago/Turabian StylePoushali Pal; Parvathy Krishnamoorthy; Devabalaji Rukmani; S. Antony; Simon Ocheme; Umashankar Subramanian; Rajvikram Elavarasan; Narottam Das; Hany Hasanien. 2021. "Optimal Dispatch Strategy of Virtual Power Plant for Day-Ahead Market Framework." Applied Sciences 11, no. 9: 3814.
Worldwide, there is a growing level of interest to develop sustainable cement-based products and processes in which the usage of natural resources such as sand and limestone are reduced from the current levels. One of the ways to achieve this is by replacing them with suitable inclusions of recycled granular materials from municipal wastes where possible. However, to understand the effects of such inclusions in concrete structures, research advancements are needed to sense and characterise the distribution of stresses (/strains) at the local scale and to establish their links with the fracture and bulk strength characteristics under external loading environments, which is the focus here. In this research, polyethylene (PE)-based granular materials derived from municipal wastes and fly ash obtained from the incineration of municipal solid wastes are used together as secondary raw materials in preparing the concrete mixtures. Photo stress analysis (PSA) is performed here, making non-contact and whole-field digital measurements of maximum shear stress distribution and the directions of the principal stresses at any point of interest on the surface of the samples under external loading. Their links with the fracture toughness and flexural strength of the samples cured at different times are presented. The novel PSA-based stresssensing helps to establish new understandings of the strength characteristics of composites across scales in the applications involving recycling and reusing conventional wastes and possibly in otherengineering applications in the future.
S. Joseph Antony; George Okeke; D. Deniz G. Tokgoz; N. Gozde Ozerkan. Whole-Field Stress Sensing and Multiscale Mechanics for Developing Cement-Based Composites Containing Recycled Municipal Granular Wastes. Sustainability 2021, 13, 848 .
AMA StyleS. Joseph Antony, George Okeke, D. Deniz G. Tokgoz, N. Gozde Ozerkan. Whole-Field Stress Sensing and Multiscale Mechanics for Developing Cement-Based Composites Containing Recycled Municipal Granular Wastes. Sustainability. 2021; 13 (2):848.
Chicago/Turabian StyleS. Joseph Antony; George Okeke; D. Deniz G. Tokgoz; N. Gozde Ozerkan. 2021. "Whole-Field Stress Sensing and Multiscale Mechanics for Developing Cement-Based Composites Containing Recycled Municipal Granular Wastes." Sustainability 13, no. 2: 848.
Silicon (Si)-based materials are sought in different engineering applications including Civil, Mechanical, Chemical, Materials, Energy and Minerals engineering. Silicon and Silicon dioxide are processed extensively in the industries in granular form, for example to develop durable concrete, shock and fracture resistant materials, biological, optical, mechanical and electronic devices which offer significant advantages over existing technologies. Here we focus on the constitutive behaviour of Si-based granular materials under mechanical shearing. In the recent times, it is widely recognised in the literature that the microscopic origin of shear strength in granular assemblies are associated with their ability to establish anisotropic networks (fabrics) comprising strong-force transmitting inter-particle contacts under shear loading. Strong contacts pertain to the relatively small number of contacts carrying greater than the average normal contact force. However, information on how such fabrics evolve in Si-based assemblies under mechanical loading, and their link to bulk shear strength of such assemblies are scarce in the literature. Using discrete element method (DEM), here we present results on how Si-based granular assemblies develop shear strength and their internal fabric structures under bi-axial quasi-static compression loading. Based on the analysis, a simple constitutive relation is presented for the bulk shear strength of the Si-based assemblies relating with their internal fabric anisotropy of the heavily loaded contacts. These findings could help to develop structure-processing property relations of Si-based materials in future, which originate at the microscale.
S. Judes Sujatha; Z. K. Jahanger; S. Barbhuiya; S. Joseph Antony. Fabrics-Shear Strength Links of Silicon-Based Granular Assemblies. Journal of Mechanics 2019, 36, 323 -330.
AMA StyleS. Judes Sujatha, Z. K. Jahanger, S. Barbhuiya, S. Joseph Antony. Fabrics-Shear Strength Links of Silicon-Based Granular Assemblies. Journal of Mechanics. 2019; 36 (3):323-330.
Chicago/Turabian StyleS. Judes Sujatha; Z. K. Jahanger; S. Barbhuiya; S. Joseph Antony. 2019. "Fabrics-Shear Strength Links of Silicon-Based Granular Assemblies." Journal of Mechanics 36, no. 3: 323-330.
Soils encounter cyclic loading conditions in situ, for example during the earthquakes and in the construction sequences of pavements. Investigations on the local scale displacements of the soil grain and their failure patterns under the cyclic loading conditions are relatively scarce in the literature. In this study, the local displacement fields of a dense sand layer interacting with a rigid footing under the plane-strain condition are examined using both experiments and simulations. Three commonly used types of cyclic loading conditions were applied on the footing. Digital particle image velocimetry (DPIV) is used to measure the local scale displacement fields in the soil, and to understand the evolution of the failure envelopes in the sand media under the cyclic loading conditions. The experimental results are compared with corresponding finite element analysis (FEA), in which experimentally-characterised constitutive relations are fed as an input into the FEM simulations. For comparison purposes, the case of footing subjected to the quasi-static loading condition was also studied. In general, the results show a good level of agreement between the results of the experiments and simulations conducted here. Overall, relatively shallower but wider displacement fields are observed under the cyclic loading, when compared with that of the quasi-static load test. The vorticity regions are highly localized at the shear bands in the sand media under the ultimate load. The research contributes to new understanding on the local scale displacement fields and their link to the bearing capacity of the footing under the cyclic loading environments.
S. J. Antony; Zuhair Kadhim Jahanger. Local Scale Displacement Fields in Grains–Structure Interactions Under Cyclic Loading: Experiments and Simulations. Geotechnical and Geological Engineering 2019, 38, 1277 -1294.
AMA StyleS. J. Antony, Zuhair Kadhim Jahanger. Local Scale Displacement Fields in Grains–Structure Interactions Under Cyclic Loading: Experiments and Simulations. Geotechnical and Geological Engineering. 2019; 38 (2):1277-1294.
Chicago/Turabian StyleS. J. Antony; Zuhair Kadhim Jahanger. 2019. "Local Scale Displacement Fields in Grains–Structure Interactions Under Cyclic Loading: Experiments and Simulations." Geotechnical and Geological Engineering 38, no. 2: 1277-1294.
In the geotechnical and terramechanical engineering applications, precise understandings are yet to be established on the off-road structures interacting with complex soil profiles. Several theoretical and experimental approaches have been used to measure the ultimate bearing capacity of the layered soil, but with a significant level of differences depending on the failure mechanisms assumed. Furthermore, local displacement fields in layered soils are not yet studied well. Here, the bearing capacity of a dense sand layer overlying loose sand beneath a rigid beam is studied under the plain-strain condition. The study employs using digital particle image velocimetry (DPIV) and finite element method (FEM) simulations. In the FEM, an experimentally characterised constitutive relation of the sand grains is fed as an input. The results of the displacement fields of the layered soil based DPIV and FEM simulations agreed well. From the DPIV experiments, a correlation between the slip surface angle and the thickness of the dense sand layer has been determined. Using this, a new and simple approach is proposed to predict theoretically the ultimate bearing capacity of the layered sand. The approach presented here could be extended more easily for analysing other complex soil profiles in the ground-structure interactions in future.
Zuhair Kadhim Jahanger; S. Joseph Antony; Elaine Martin; Lutz Richter. Interaction of a rigid beam resting on a strong granular layer overlying weak granular soil: Multi-methodological investigations. Journal of Terramechanics 2018, 79, 23 -32.
AMA StyleZuhair Kadhim Jahanger, S. Joseph Antony, Elaine Martin, Lutz Richter. Interaction of a rigid beam resting on a strong granular layer overlying weak granular soil: Multi-methodological investigations. Journal of Terramechanics. 2018; 79 ():23-32.
Chicago/Turabian StyleZuhair Kadhim Jahanger; S. Joseph Antony; Elaine Martin; Lutz Richter. 2018. "Interaction of a rigid beam resting on a strong granular layer overlying weak granular soil: Multi-methodological investigations." Journal of Terramechanics 79, no. : 23-32.
The focus of this work is on systematically understanding the effects of packing density of the sand grains on both the internal and bulk mechanical properties for strip footing interacting with granular soil. The studies are based on particle image velocimetry (PIV) method, coupled with a high resolution imaging camera. This provides valuable new insights on the evolution of slip planes at grain-scale under different fractions of the ultimate load. Furthermore, the PIV based results are compared with finite element method simulations in which the experimentally characterised parameters and constitutive behaviour are fed as an input, and a good level of agreements are obtained. The reported results would serve to the practicing engineers, researchers and graduate students in unravelling the mechanics of granular soil at both local and global levels when they interact with structures. The outcomes would be beneficial not only to the geotechnical engineering community, but also to related disciplines dealing with granular materials such as materials processing, minerals and space exploration.
Z. K. Jahanger; J. Sujatha; S. J. Antony. Local and Global Granular Mechanical Characteristics of Grain–Structure Interactions. Indian Geotechnical Journal 2018, 48, 753 -767.
AMA StyleZ. K. Jahanger, J. Sujatha, S. J. Antony. Local and Global Granular Mechanical Characteristics of Grain–Structure Interactions. Indian Geotechnical Journal. 2018; 48 (4):753-767.
Chicago/Turabian StyleZ. K. Jahanger; J. Sujatha; S. J. Antony. 2018. "Local and Global Granular Mechanical Characteristics of Grain–Structure Interactions." Indian Geotechnical Journal 48, no. 4: 753-767.
S. Joseph Antony; Babatunde Arowosola; Lutz Richter; Tulegen Amanbayev; Thabit Barakat. Flow Behavior of Grains through the Dosing Station of Spacecraft under Low-Gravity Environments. Journal of Aerospace Engineering 2017, 30, 04017078 .
AMA StyleS. Joseph Antony, Babatunde Arowosola, Lutz Richter, Tulegen Amanbayev, Thabit Barakat. Flow Behavior of Grains through the Dosing Station of Spacecraft under Low-Gravity Environments. Journal of Aerospace Engineering. 2017; 30 (6):04017078.
Chicago/Turabian StyleS. Joseph Antony; Babatunde Arowosola; Lutz Richter; Tulegen Amanbayev; Thabit Barakat. 2017. "Flow Behavior of Grains through the Dosing Station of Spacecraft under Low-Gravity Environments." Journal of Aerospace Engineering 30, no. 6: 04017078.
We present a hybrid framework for simulating the strength and dilation characteristics of sandstone. Where possible, the grain-scale properties of sandstone are evaluated experimentally in detail. Also, using photo-stress analysis, we sense the deviator stress (/strain) distribution at the micro-scale and its components along the orthogonal directions on the surface of a V-notch sandstone sample under mechanical loading. Based on this measurement and applying a grain-scale model, the optical anisotropy index K0 is inferred at the grain scale. This correlated well with the grain contact stiffness ratio K evaluated using ultrasound sensors independently. Thereafter, in addition to other experimentally characterised structural and grain-scale properties of sandstone, K is fed as an input into the discrete element modelling of fracture strength and dilation of the sandstone samples. Physical bulk-scale experiments are also conducted to evaluate the load–displacement relation, dilation and bulk fracture strength characteristics of sandstone samples under compression and shear. A good level of agreement is obtained between the results of the simulations and experiments. The current generic framework could be applied to understand the internal and bulk mechanical properties of such complex opaque and heterogeneous materials more realistically in future.
S. J. Antony; A. Olugbenga; N. G. Ozerkan. Sensing, Measuring and Modelling the Mechanical Properties of Sandstone. Rock Mechanics and Rock Engineering 2017, 51, 451 -464.
AMA StyleS. J. Antony, A. Olugbenga, N. G. Ozerkan. Sensing, Measuring and Modelling the Mechanical Properties of Sandstone. Rock Mechanics and Rock Engineering. 2017; 51 (2):451-464.
Chicago/Turabian StyleS. J. Antony; A. Olugbenga; N. G. Ozerkan. 2017. "Sensing, Measuring and Modelling the Mechanical Properties of Sandstone." Rock Mechanics and Rock Engineering 51, no. 2: 451-464.
Fracture toughness measures the resistance of a material to fracture. This fundamental property is used in diverse engineering designs including mechanical, civil, materials, electronics and chemical engineering applications. In spite of the advancements made in the past 40 years, the evaluation of this remains challenging for extremely heterogeneous materials such as composite concretes. By taking advantage of the optical properties of a thin birefringent coating on the surface of opaque, notched composite concrete beams, here we sense the evolution of the maximum shear stress distribution on the beams under loading. The location of the maximum deviator stress is tracked ahead of the crack tip on the experimental concrete samples under the ultimate load, and hence the effective crack length is characterised. Using this, the fracture toughness of a number of heterogeneous composite beams is evaluated and the results compare favourably well with other conventional methods using combined experimental and numerical/analytical approaches. Finally a new model, correlating the optically measured shear stress concentration factor and flexural strength with the fracture toughness of concretes is proposed. The current photonics-based study could be vital in evaluating the fracture toughness of even opaque and complex heterogeneous materials more effectively in future.
S. Joseph Antony; George Okeke; D. Deniz Genc Tokgoz; N. Gozde Ozerkan. Photonics and fracture toughness of heterogeneous composite materials. Scientific Reports 2017, 7, 4539 .
AMA StyleS. Joseph Antony, George Okeke, D. Deniz Genc Tokgoz, N. Gozde Ozerkan. Photonics and fracture toughness of heterogeneous composite materials. Scientific Reports. 2017; 7 (1):4539.
Chicago/Turabian StyleS. Joseph Antony; George Okeke; D. Deniz Genc Tokgoz; N. Gozde Ozerkan. 2017. "Photonics and fracture toughness of heterogeneous composite materials." Scientific Reports 7, no. 1: 4539.
Engineering nanowires to develop new products and processes is highly topical due to their ability to provide highly enhanced physical, chemical, mechanical, thermal and electrical properties. In this work, using molecular dynamics simulations, we report fundamental information, about the structural and thermodynamic properties of individual anatase titania (TiO2) nanowires with cross-sectional diameters between 2 and 6 nm, and aspect ratio (length to diameter) of 6:1 at temperatures ranging from 300 to 3000 K. Estimates of the melting transition temperature of the nanowires are between 2000 and 2500 K. The melting transition temperature predicted from the radial distribution functions (RDFs) shows strong agreement with those predicted from the total energy profiles. Overall, the transition temperature is in reasonable agreement with melting points predicted from experiments and simulations reported in the literature for spherical nanoparticles of similar sizes. Hence, the melting transition temperature of TiO2 nanowires modelled here can be considered as shape independent. Furthermore, for the first time based on MD simulations, interaction forces between two nanowires are reported at ambient temperature (300 K) for different orientations: parallel, perpendicular and end-to-end. It is observed that end-to-end orientations manifested the strongest attraction forces, while the parallel and perpendicular orientations displayed weaker attractions. The results reported here could form a foundation in future multiscale modelling studies of the structured titania nanowire assemblies, depending on the inter-wire interaction forces.
George Okeke; S. Joseph Antony; Robert Hammond; Kamran Ahmed. Structures and orientation-dependent interaction forces of titania nanowires using molecular dynamics simulations. Journal of Nanoparticle Research 2017, 19, 237 .
AMA StyleGeorge Okeke, S. Joseph Antony, Robert Hammond, Kamran Ahmed. Structures and orientation-dependent interaction forces of titania nanowires using molecular dynamics simulations. Journal of Nanoparticle Research. 2017; 19 (7):237.
Chicago/Turabian StyleGeorge Okeke; S. Joseph Antony; Robert Hammond; Kamran Ahmed. 2017. "Structures and orientation-dependent interaction forces of titania nanowires using molecular dynamics simulations." Journal of Nanoparticle Research 19, no. 7: 237.
Nanomaterials have become a widely used group of materials in many chemical engineering applications owing to their ability to provide an enhanced level of functional properties compared to their crystalline and bulk counterparts. Here we report fundamental level advancements on how the anatase and rutile phase of TiO2 nanoparticles chemo-thermally respond between room temperature and the melting temperature under both vacuum and water environments. The current study is based on using molecular dynamics (MD) simulations. We present results on the equilibrium crystal morphology of these phases, structural and surface energy of TiO2 nanoparticles in the size range of 2–6 nm under different temperatures. Thermodynamic and structural properties, in the form of potential energy and Radial Distribution Functions (RDF’s) respectively, are calculated for both forms of TiO2 nanoparticles. The temperature associated with the melting transition increased with an increase in the particle size in both the phases. The potential energy change associated with the melting transition for anatase was seen to be less than that for rutile nanoparticles. Also the temperature at which the RDF’s began to stretch and broaden was observed to be lower for the case of anatase than rutile, suggesting that rutile attains the most thermal stable phase for the nano particle sizes considered in this study. Structural changes in anatase and rutile nanoparticles under different temperatures revealed that non-spherical (rod-like) rutile nanoparticles tend to be thermodynamically more stable. Surface energy influences the shape of TiO2 nanoparticles at different temperatures. The increase in the surface energy of nanoparticles under vacuum when compared with that of water environment is higher for the anatase phase than the rutile phase of nanoparticle sizes studied here. The fundamental level simulation results reported here provide a strong platform for potentially accounting for the effects of atomic-scale phase characteristics of TiO2 nanoparticles and surface energy under different temperature fields in nano processing applications and related multi-scale modelling approaches in future.
George Okeke; Robert Hammond; Simon Joseph Antony. Effects of heat treatment on the atomic structure and surface energy of rutile and anatase TiO2 nanoparticles under vacuum and water environments. Chemical Engineering Science 2016, 146, 144 -158.
AMA StyleGeorge Okeke, Robert Hammond, Simon Joseph Antony. Effects of heat treatment on the atomic structure and surface energy of rutile and anatase TiO2 nanoparticles under vacuum and water environments. Chemical Engineering Science. 2016; 146 ():144-158.
Chicago/Turabian StyleGeorge Okeke; Robert Hammond; Simon Joseph Antony. 2016. "Effects of heat treatment on the atomic structure and surface energy of rutile and anatase TiO2 nanoparticles under vacuum and water environments." Chemical Engineering Science 146, no. : 144-158.
The European Space Agency (ESA) will launch the EXOMARS rover mission to Mars in 2018 which will operate a rover for subsurface soil sampling and analysis. Using several electro-mechanical systems within the rover, samples acquired will be mechanically processed and dispensed to instruments. For designing the grain-processing stations of spacecraft such as EXOMARS require reliable estimates on the internal and bulk flow characteristics of granular media under low gravitational environments. However, the micromechanical behaviour of granular materials under low-gravitational environments is still complex to understand. Experimental studies on the flow behaviour of grain under a low gravity, for example, using parabolic flight tests to simulate Martian gravity, are difficult to perform and expensive. Using computational modelling, here we present results on the flow behaviour of granular materials through flow channels under different gravity conditions including the low-gravity regime. For this, we use three approaches, viz., (i) one-dimensional discrete layer approach (DLA) based on hybrid-Lagrange continuum approach, (ii) three dimensional Kirya continuum model, and (iii) three dimensional discrete element modelling (DEM). Each model has its merits and limitations. Some qualitative comparisons are also made between the flow characteristics of grains observed from parabolic flight tests and DEM simulations.
S. J. Antony; B. Arowosola; L. Richter; T. Amanbayev; T. Barakat. Granular Materials in Space Exploration. Earth and Space 2016 2016, 1 .
AMA StyleS. J. Antony, B. Arowosola, L. Richter, T. Amanbayev, T. Barakat. Granular Materials in Space Exploration. Earth and Space 2016. 2016; ():1.
Chicago/Turabian StyleS. J. Antony; B. Arowosola; L. Richter; T. Amanbayev; T. Barakat. 2016. "Granular Materials in Space Exploration." Earth and Space 2016 , no. : 1.
In the exploration of planetary materials using robotic probes, one of the key priorities is to establish fundamental level understandings on the mechanical response of materials under different levels of loading. In this context, though a number of strength characterisation tools are applied in the space industry, whole-field visualization of stress and temperature distribution on rock samples and their potential relevance to fracture under external loading is not yet well exploited. In this work, we apply two types of tomography namely (i) IR tomography and (ii) PSAT tomography to understand the variation of temperature and shear stress distribution respectively anywhere on the samples at point scale. Sandstone is used as a simulant material here. Potential links between the tomography measures and the fracture strength of the sandstone are revealed in this work.
S. J. Antony; A. Olugbenga; N. Ozerkan; O. Marumoame; G. Okeke. Advanced Materials and Designs for Hydraulic, Earth, and Aerospace Structures. Earth and Space 2016 2016, 1 .
AMA StyleS. J. Antony, A. Olugbenga, N. Ozerkan, O. Marumoame, G. Okeke. Advanced Materials and Designs for Hydraulic, Earth, and Aerospace Structures. Earth and Space 2016. 2016; ():1.
Chicago/Turabian StyleS. J. Antony; A. Olugbenga; N. Ozerkan; O. Marumoame; G. Okeke. 2016. "Advanced Materials and Designs for Hydraulic, Earth, and Aerospace Structures." Earth and Space 2016 , no. : 1.
An experimental study is presented here to understand the stress transmission characteristics under different geometrical arrangements of particulates inside a narrow chamber subjected to axial compression loading. The multi-grain systems considered here are face-centred, simple cubic and poly-dispersed structures, as well as inclusions embedded inside seeded, unseeded and cohesive powder bed of Durcal (calcium carbonate). The distribution of the maximum shear stress, direction of the major principal stress and shear stress concentration factor were obtained using photo stress analysis tomography (PSAT). The results show that the maximum shear stress distribution in the simple cubic structure is chain-like and self-repetitive, i.e., a single grain behaviour is representative of the whole system. This is not the case in the case of other granular packing. In the case of the inclusion surrounded by powder media, the maximum shear stress distribution in the inclusion occurs through ring-like structures, which are different from those observed in the structured granular packing. This tendency increases for an increase in the cohesivity of the surrounding particulates. In the granular systems, the direction of the major principal stress is mostly orthogonal to the direction of loading except in some particles in the random granular packing. In the case of inclusion surrounded by Durcal particulates, the directional of the major principal stress acts along the direction of the axial loading except in the ring region where this tends to be oblique to the direction of axial loading. Estimates of the shear stress concentration factor (k) show that, k tends to be independent of the structural arrangement of granular packing at higher load levels. In the case of inclusion surrounded by powder bed, k for the seeded granulated particulate bed is mostly independent of the external load levels. In the case of unseeded particulate (granulated) bed, a fluctuation in k is observed with the loading level. This suggests that the seeded granules could distribute stresses in a stable manner without much change in the nature of shear stress-transmitting fabric of the particulate contacts under external loading. An increase in the cohesion of particulate bed results in more plastic deformation as shown by the differential shear stress concentration factor. The results reported in this study show the usefulness of optical stress analysis to shed some scientific lights on unravelling some of the complexities of particulate systems under different structural arrangements of grains and surrounding conditions of the inclusions in particulate media.
S.J. Antony; M. Al-Sharabi; Nejat Rahmanian; T. Barakat. Shear stress distribution within narrowly constrained structured grains and granulated powder beds. Advanced Powder Technology 2015, 26, 1702 -1711.
AMA StyleS.J. Antony, M. Al-Sharabi, Nejat Rahmanian, T. Barakat. Shear stress distribution within narrowly constrained structured grains and granulated powder beds. Advanced Powder Technology. 2015; 26 (6):1702-1711.
Chicago/Turabian StyleS.J. Antony; M. Al-Sharabi; Nejat Rahmanian; T. Barakat. 2015. "Shear stress distribution within narrowly constrained structured grains and granulated powder beds." Advanced Powder Technology 26, no. 6: 1702-1711.
D D Tokgoz; N G Ozerkan; O S Kowita; S J Antony. Mechanical Performance of Self Consolidating Concrete containing Plastic Waste Particles. Third International Conference on Advances In Civil, Structural and Environmental Engineering- ACSEE 2015 2015, 1 .
AMA StyleD D Tokgoz, N G Ozerkan, O S Kowita, S J Antony. Mechanical Performance of Self Consolidating Concrete containing Plastic Waste Particles. Third International Conference on Advances In Civil, Structural and Environmental Engineering- ACSEE 2015. 2015; ():1.
Chicago/Turabian StyleD D Tokgoz; N G Ozerkan; O S Kowita; S J Antony. 2015. "Mechanical Performance of Self Consolidating Concrete containing Plastic Waste Particles." Third International Conference on Advances In Civil, Structural and Environmental Engineering- ACSEE 2015 , no. : 1.
Healthy eyes are vital for a better quality of human life. Historically, for man-made materials, scientists and engineers use stress concentration factors to characterise the effects of structural non-homogeneities on their mechanical strength. However, such information is scarce for the human eye. Here we present the shear stress distribution profiles of a healthy human cornea surface in vivo using photo-stress analysis tomography, which is a non-intrusive and non-X-ray based method. The corneal birefringent retardation measured here is comparable to that of previous studies. Using this, we derive eye stress concentration factors and the directional alignment of major principal stress on the surface of the cornea. Similar to thermometers being used for monitoring the general health in humans, this report provides a foundation to characterise the shear stress carrying capacity of the cornea, and a potential bench mark for validating theoretical modelling of stresses in the human eye in future.
S. Joseph Antony. Imaging shear stress distribution and evaluating the stress concentration factor of the human eye. Scientific Reports 2015, 5, 8899 .
AMA StyleS. Joseph Antony. Imaging shear stress distribution and evaluating the stress concentration factor of the human eye. Scientific Reports. 2015; 5 (1):8899.
Chicago/Turabian StyleS. Joseph Antony. 2015. "Imaging shear stress distribution and evaluating the stress concentration factor of the human eye." Scientific Reports 5, no. 1: 8899.
Nanoparticles have attracted the attention of researchers in a number of multidisciplinary fields as they possess enhanced structural and physical properties, which make them desirable to a wide range of industries. These enhancements have mostly been attributed to their large surface area-to-volume ratio. However, the effect of temperature on the structural and surface properties of nanoparticles of different sizes is still not well understood, an aspect addressed in the present work. Using molecular dynamics simulations, we have performed investigations on anatase TiO2 nanoparticles with sizes ranging between 2 and 6 nm and at different temperatures. Structural and surface properties including surface energies are reported for the different nanoparticle sizes, temperature and simulation time step. Comparisons of surface energies for the different nanoparticle sizes show that surface energy increases to a maximum (optimum value) especially for temperatures between 300 and 1,500 K, as the particle size increases after which no further significant increase is observed. Studies conducted on the change of final structure with respect to the initial structure of the particles, revealed that atomic structural disordering is more visible at the surface layer compared to the bulk or core of the final structure. Further studies conducted on the sphericity of the nanoparticles showed that the particles became less spherical with increase in temperature.
George Okeke; Robert B. Hammond; S. Joseph Antony. Influence of size and temperature on the phase stability and thermophysical properties of anatase TiO2 nanoparticles: molecular dynamics simulation. Journal of Nanoparticle Research 2013, 15, 1 .
AMA StyleGeorge Okeke, Robert B. Hammond, S. Joseph Antony. Influence of size and temperature on the phase stability and thermophysical properties of anatase TiO2 nanoparticles: molecular dynamics simulation. Journal of Nanoparticle Research. 2013; 15 (4):1.
Chicago/Turabian StyleGeorge Okeke; Robert B. Hammond; S. Joseph Antony. 2013. "Influence of size and temperature on the phase stability and thermophysical properties of anatase TiO2 nanoparticles: molecular dynamics simulation." Journal of Nanoparticle Research 15, no. 4: 1.
Numerical investigations are conducted to study the effect of factors such as particle clustering and interfacial layer thickness on thermal conductivity of nanofluids. Based on this, parameters including Kapitza radius and fractal and chemical dimension which have received little attention by previous research are rigorously investigated. The degree of thermal enhancement is analyzed for increasing aggregate size, particle concentration, interfacial thermal resistance, and fractal and chemical dimensions. This analysis is conducted for water-based nanofluids of Alumina (Al2O3), CuO, and Titania (TiO2) nanoparticles where the particle concentrations are varied up to 4 vol%. Results from the numerical work are validated using available experimental data. For the case of aggregate size, particle concentration, and interfacial thermal resistance, the aspect ratio (ratio of radius of gyration of aggregate to radius of primary particle, R g/a) is varied from 2 to 60. It was found that the enhancement decreases with interfacial layer thickness. Also the rate of decrease is more significant after a given aggregate size. For a given interfacial resistance, the enhancement is mostly sensitive to R g/a < 20 indicated by the steep gradients of data plots. Predicted and experimental data for thermal conductivity enhancement are in good agreement. On the influence of fractal and chemical dimensions (d land d f) of Alumina–water nanofluid, the R g/a was varied from 2 to 8, d l from 1.2 to 1.8, and d f from 1.75 to 2.5. For a given concentration, the enhancement increased with the reduction of d l or d f. It appears a distinctive sensitivity of the enhancement to d f, in particular, in the range 2–2.25, for all values of R g/a. However, the sensitivity of d l was largely depended on the value of R g/a. The information gathered from this study on the sensitivity of thermal conductivity enhancement to aggregate size, particle concentration, interfacial resistance, and fractal and chemical dimensions will be useful in manufacturing highly thermally conductive nanofluids. Further research on the refine cluster evolution dynamics as a function of particle-scale properties is underway.
G. Okeke; Sanjeeva Witharana; S. J. Antony; Y. Ding. Computational analysis of factors influencing thermal conductivity of nanofluids. Journal of Nanoparticle Research 2011, 13, 6365 -6375.
AMA StyleG. Okeke, Sanjeeva Witharana, S. J. Antony, Y. Ding. Computational analysis of factors influencing thermal conductivity of nanofluids. Journal of Nanoparticle Research. 2011; 13 (12):6365-6375.
Chicago/Turabian StyleG. Okeke; Sanjeeva Witharana; S. J. Antony; Y. Ding. 2011. "Computational analysis of factors influencing thermal conductivity of nanofluids." Journal of Nanoparticle Research 13, no. 12: 6365-6375.
T. Amanbayev; G. Okeke; M. Afzal; S.J. Antony. Modelling of Bacterial Growth in Nano Liquids. Proceedings of the Seventh International Conference on Engineering Computational Technology 2010, 1 .
AMA StyleT. Amanbayev, G. Okeke, M. Afzal, S.J. Antony. Modelling of Bacterial Growth in Nano Liquids. Proceedings of the Seventh International Conference on Engineering Computational Technology. 2010; ():1.
Chicago/Turabian StyleT. Amanbayev; G. Okeke; M. Afzal; S.J. Antony. 2010. "Modelling of Bacterial Growth in Nano Liquids." Proceedings of the Seventh International Conference on Engineering Computational Technology , no. : 1.
Roberto Moreno-Atanasio; S.J. Antony. Micromechanical Behaviour of Granular Media: Effects of Contact Stiffnesses. Proceedings of the Fifth International Conference on Engineering Computational Technology 2009, 1 .
AMA StyleRoberto Moreno-Atanasio, S.J. Antony. Micromechanical Behaviour of Granular Media: Effects of Contact Stiffnesses. Proceedings of the Fifth International Conference on Engineering Computational Technology. 2009; ():1.
Chicago/Turabian StyleRoberto Moreno-Atanasio; S.J. Antony. 2009. "Micromechanical Behaviour of Granular Media: Effects of Contact Stiffnesses." Proceedings of the Fifth International Conference on Engineering Computational Technology , no. : 1.