2D dynamic analysis of cracks and interface cracks in piezoelectric composites using the SBFEM
- Authors: Li, Chao , Song, Chongmin , Man, Hou , Ooi, Ean Tat , Gao, Wei
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal of Solids and Structures Vol. 51, no. 11-12 (June 2014), p. 2096-2108
- Full Text: false
- Reviewed:
- Description: The dynamic stress and electric displacement intensity factors of impermeable cracks in homogeneous piezoelectric materials and interface cracks in piezoelectric bimaterials are evaluated by extending the scaled boundary finite element method (SBFEM). In this method, a piezoelectric plate is divided into polygons. Each polygon is treated as a scaled boundary finite element subdomain. Only the boundaries of the subdomains need to be discretized with line elements. The dynamic properties of a subdomain are represented by the high order stiffness and mass matrices obtained from a continued fraction solution, which is able to represent the high frequency response with only 3-4 terms per wavelength. The semi-analytical solutions model singular stress and electric displacement fields in the vicinity of crack tips accurately and efficiently. The dynamic stress and electric displacement intensity factors are evaluated directly from the scaled boundary finite element solutions. No asymptotic solution, local mesh refinement or other special treatments around a crack tip are required. Numerical examples are presented to verify the proposed technique with the analytical solutions and the results from the literature. The present results highlight the accuracy, simplicity and efficiency of the proposed technique.
3D Finite element modeling of circular reinforced concrete columns confined with FRP using a plasticity based formulation
- Authors: Piscesa, Bambang , Attard, Mario , Samani, Ali Khajeh
- Date: 2018
- Type: Text , Journal article
- Relation: Composite Structures Vol. 194, no. (2018), p. 478-493
- Full Text: false
- Reviewed:
- Description: Strengthening reinforced concrete (RC) columns with external confining devices such as FRP wraps or steel tube is widely used in construction. By using external confining devices, both the strength and ductility of RC columns are significantly improved. However, numerical modeling to predict the capacity of strengthened RC columns is limited and often oversimplified. One of the biggest challenges in numerical modeling is to deal with unequal dilation between the concrete inner core (enclosed by both transverse steel and FRP wraps) and the concrete outer core (between the transverse steel and FRP wraps). Inaccurate modeling on the concrete dilatant behavior can lead to incorrect strength prediction. Sophisticated constitutive models which are able to model concrete dilation and robust modeling techniques are required. In this paper, three-dimensional non-linear finite element analysis (3D-NLFEA) of circular RC columns confined with conventional steel stirrups and FRP wraps is presented. In the FEA, the initial stiffness method with Process Modification (acceleration technique) is used to solve the equilibrium forces in the global solution. The constitutive model is based on the plasticity formulation proposed by the authors, which can capture the effective lateral modulus (EL) of the confining devices. This lateral modulus is obtained by observing the principal incremental stresses and strains at each element gauss point. It was found that, the lateral modulus is greatly affected by the boundary condition, dilatant behavior of the constitutive model and the Poisson's ratio of the external confining device. To validate the performance of the proposed model, several comparisons of the proposed model, using 3D-NLFEA, with experimental results is presented. The comparisons show that the predicted response using 3D-NLFEA and the experimental results of RC columns confined with FRP are in a good agreement.
3D Integrated numerical model for fluid-structures-seabed interaction (FSSI) : Elastic dense seabed foundation
- Authors: Jianhong, Ye , Jeng, Dong-Shen , Chan, Andrew , Wang, R. , Zhu, Q. C.
- Date: 2016
- Type: Text , Journal article
- Relation: Ocean Engineering Vol. 115, no. (2016), p. 107-122
- Full Text: false
- Reviewed:
- Description: Economic losses and property damage due to the failure of offshore structures are huge each year in the world, under the attack of endless conventional wave, occasional tropical storms or typhoons, and possible tsunami. Wave-induced dynamics of offshore structures and their seabed foundation attract a great deal of attention from researchers and ocean engineers. Previous literature investigated the wave-structures-seabed interaction generally adopting 2D models and decoupled way. In this study, taking a caisson breakwater as the typical offshore structure, the simple linear interaction between ocean wave, a caisson breakwater and its poro-elastic seabed foundation is investigated by utilizing a three-dimensional integrated numerical model FSSI-CAS 3D. The numerical results indicate that FSSI-CAS 3D can effectively and sufficiently capture a variation of phenomena of wave-induced dynamics of offshore structures, and momentary liquefaction in its dense poro-elastic seabed foundation. This study demonstrates great promise of using the developed integrated numerical model in offshore industry to predict the dynamic response and stability of offshore structures by ocean engineers in design stage. © 2016 Elsevier Ltd. All rights reserved.
A combined virtual element method and the scaled boundary finite element method for linear elastic fracture mechanics
- Authors: Adak, Dibyendu , Pramod, ALN , Ooi, Ean Tat , Natarajan, Sundararajan
- Date: 2020
- Type: Text , Journal article
- Relation: Engineering Analysis with Boundary Elements Vol. 113, no. (2020), p. 9-16
- Full Text: false
- Reviewed:
- Description: In this paper, we propose a framework that combines the recently introduced virtual element method (VEM) and the scaled boundary finite element method (SBFEM) to evaluate the fracture parameters. The domain is discretized with arbitrary polygons and the element that contains the crack tip is treated within the framework of the SBFEM. This facilitates a semi-analytical treatment of the crack tip singularity allowing the fracture parameters are estimated directly from the definition. The VEM is employed for the rest of the domain. The salient feature of the VEM is that the terms in the stiffness matrix are computed without requiring higher order quadrature schemes. As both the methods satisfy partition of unity and the compatibility condition, the matrices are assembled as in the conventional FEM. The accuracy of the proposed formulation is demonstrated with two standard benchmark examples. The proposed VEM-SBFEM framework yields accurate results. © 2019 Elsevier Ltd
A comparative study of two embodiments of the limaçon rotary compressor based on theoretical modelling of apex seal dynamics and leakage
- Authors: Lu, Kui , Sultan, Ibrahim , Phung, Truong
- Date: 2023
- Type: Text , Journal article
- Relation: International Journal of Refrigeration Vol. 145, no. (2023), p. 467-480
- Full Text: false
- Reviewed:
- Description: As an emerging technology, the limaçon rotary compressor possesses great potential for fluid-processing applications. However, the technology and associated cost required to fabricate the limaçon machine could sometimes be beyond the capability of some manufacturers. To reduce the production cost, circolimaçon embodiment whose rotor and housing are constructed of circular arcs has been proposed. This paper is intended to investigate the viability of the circolimaçon embodiment of limaçon technology based on sealing performance. A nonlinear three-degree of freedom model is presented to describe the dynamic behaviour of the apex seal during the machine operation. Additionally, the leakage through the seal-housing gap is formulated by considering the inertia and viscous effects on the flow. A numerical illustration is offered to compare the performance of the circolimaçon embodiment with that of the limaçon-to-limaçon (L2L) type machine at different pressure ratios and operating speeds. The effect of limaçon aspect ratio on the apex seal dynamics is also investigated. Based on the results, it is found that the circolimaçon embodiment exhibits comparable performance to the L2L-type machine, despite having more significant seal vibrations. The differences in the volumetric and isentropic efficiencies between the two machines are found within 8% and 3%, respectively. Additionally, it is also discovered that the circolimaçon compressor with a small capacity undergoes lower level of seal dynamics, suggesting a better machine reliability. © 2022
A computational framework to simulate the thermochemical process during thermochemical ablation of biological tissues
- Authors: Mak, Nguoy , Ooi, Ean H. , Lau, Ee , Ooi, Ean Tat , Pamidi, N. , Foo, Ji , Mohd Ali, Ahmad
- Date: 2022
- Type: Text , Journal article
- Relation: Computers in Biology and Medicine Vol. 145, no. (2022), p.
- Full Text: false
- Reviewed:
- Description: Thermochemical ablation (TCA) is a thermal ablation therapy that utilises heat released from acid-base neutralisation reaction to destroy tumours. This procedure is a promising low-cost solution to existing thermal ablation treatments such as radiofrequency ablation (RFA) and microwave ablation (MWA). Studies have demonstrated that TCA can produce thermal damage that is on par with RFA and MWA when employed properly. Nevertheless, TCA remains a concept that is tested only in a few animal trials due to the risks involved as the result of uncontrolled infusion and incomplete acid-base reaction. In this study, a computational framework that simulates the thermochemical process of TCA is developed. The proposed framework consists of three physics, namely chemical flow, neutralisation reaction and heat transfer. An important parameter in the TCA framework is the neutralisation reaction rate constant, which has values in the order of 108 m3/(mol
A computational model to investigate the influence of electrode lengths on the single probe bipolar radiofrequency ablation of the liver
- Authors: Cheong, Jason , Yap, Shelley , Ooi, Ean Tat , Ooi, Ean Hin
- Date: 2019
- Type: Text , Journal article
- Relation: Computer Methods and Programs in Biomedicine Vol. 176, no. (2019), p. 17-32
- Full Text: false
- Reviewed:
- Description: Background and objectives: Recently, there have been calls for RFA to be implemented in the bipolar mode for cancer treatment due to the benefits it offers over the monopolar mode. These include the ability to prevent skin burns at the grounding pad and to avoid tumour track seeding. The usage of bipolar RFA in clinical practice remains uncommon however, as not many research studies have been carried out on bipolar RFA. As such, there is still uncertainty in understanding the effects of the different RF probe configurations on the treatment outcome of RFA. This paper demonstrates that the electrode lengths have a strong influence on the mechanics of bipolar RFA. The information obtained here may lead to further optimization of the system for subsequent uses in the hospitals. Methods: A 2D model in the axisymmetric coordinates was developed to simulate the electro-thermophysiological responses of the tissue during a single probe bipolar RFA. Two different probe configurations were considered, namely the configuration where the active electrode is longer than the ground and the configuration where the ground electrode is longer than the active. The mathematical model was first verified with an existing experimental study found in the literature. Results: Results from the simulations showed that heating is confined only to the region around the shorter electrode, regardless of whether the shorter electrode is the active or the ground. Consequently, thermal coagulation also occurs in the region surrounding the shorter electrode. This opened up the possibility for a better customized treatment through the development of RF probes with adjustable electrode lengths. Conclusions: The electrode length was found to play a significant role on the outcome of single probe bipolar RFA. In particular, the length of the shorter electrode becomes the limiting factor that influences the mechanics of single probe bipolar RFA. Results from this study can be used to further develop and optimize bipolar RFA as an effective and reliable cancer treatment technique. (C) 2019 Elsevier B.V. All rights reserved.
A content analysis of cross-cultural motivational studies in tourism relating to nationalities
- Authors: Soldatenko, Daria , Backer, Elisa
- Date: 2019
- Type: Text , Journal article
- Relation: Journal of Hospitality and Tourism Management Vol. 38, no. (2019), p. 122-139
- Full Text: false
- Reviewed:
- Description: The importance of outbound markets to a host country has increased scholars' interest in understanding motivational factors. Motivation is a basic determinant of tourists' behaviour and has a fundamental role in tourism. The awareness of motivational differences among tourists from main generating markets is a prerequisite for effective and successful destination marketing programs. However, cross-cultural motivation comparisons of tourists from different cultural backgrounds has received relatively little research attention. In addition, there has not been a content analysis undertaken on this topic. Therefore, the aim of this research was to examine and synthesise previous studies on cross-cultural tourist motivation comparison, reveal the gaps in the literature and indicate the future research trends. A review of 71 publications covering a period of 30 years, from 1988 to 2017, was conducted. This study focuses on both subject areas and research methods used. The findings of this content analysis identified a recent growth in cross-cultural comparison studies. The analysis also revealed an increase in more advanced analysis including multiple variables such as motivations, satisfaction, segmentation of visitors, intention behaviours, and information search behaviour. The analysis of nationalities compared in the reviewed studies indicated the shift of research interest towards Asian countries. In the case of research methods, quantitative design is more common for cross-cultural motivation studies.
A content analysis of Visiting Friends and Relatives (VFR) travel research
- Authors: Yousuf, Mohammad , Backer, Elisa
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Hospitality and Tourism Management Vol. 25, no. (2015), p. 1-10
- Full Text: false
- Reviewed:
- Description: Visiting Friends and Relatives (VFR) travel is a significant form of tourism worldwide. Scholarly research into VFR commenced in 1990 and since then only one review of the literature has been conducted, which was a content analysis based exclusively on journal articles. That research, based from 1990 to 2010 highlighted that only 39 VFR articles had been published in tourism journals. Given the small number of publications identified, it was felt that an analysis encompassing a wider selection of publication forums and extended to 2015 would be valuable to scholarship. This research also considered citations and outputs by individual authors to determine where research is being derived from. The findings of this research identified recent growth in VFR travel research from wider publication forums, including conference papers and theses. However, VFR has made the most presence through book chapters in recent years. VFR research has historically focused on the commercial and marketing aspects, but more recently has turned to furthering understanding of the social aspects by giving particular importance to the VFR hosts and migration topics for the future direction of VFR research. © 2015 The Authors.
A continental narrative : Human settlement patterns and Australian climate change over the last 35,000 years
- Authors: Williams, Alan , Veth, Peter , Steffen, Will , Ulm, Sean , Turney, Chris , Reeves, Jessica , Phipps, Steven , Smith, Mike
- Date: 2015
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 123, no. (2015), p. 91-112
- Full Text: false
- Reviewed:
- Description: Drawing on the recent synthesis of Australian palaeoclimate by the OZ-INTIMATE group (Reeves etal., 2013a), we consider the effects of climate systems on past human settlement patterns and inferred demography. We use 5044 radiocarbon dates from ~1750 archaeological sites to develop regional time-series curves for different regions defined in the OZ-INTIMATE compilation as the temperate, tropics, interior and Southern Ocean sectors to explore human-climate relationships in Australia over the last 35,000 years. Correlations undertaken with improved palaeoclimatic data and archaeological records indicate that the regional time-series curves are robust, and can be used as a proxy for human behaviour. However, interrogation of the datasets is essential with artificial peaks and taphonomic over-correction being critical considerations. The time-series curves are interpreted as reflecting population growth, stasis and even decline in phase with terminal Pleistocene/early Holocene climatic fluctuations. This coupling, however, decreases during the last 5000 years, most likely due to increased population levels, greater territoriality, technological solutions to stress, and social and ideational innovation. Curves from all sectors show exponential population growth over the last 5000 years. We identify future research priorities, highlighting the paucity of archaeological records across several parts of Australia (<1 dated site/4,000km2), especially around the fringes of the arid zone, and the need for improved taphonomic correction techniques. Finally, we discuss how these time-series curves represent a first-order framework, not dissimilar to global climate models, which researchers can continue to test and refine with local, regional and continental records. © 2015.
A convolutional recursive modified Self Organizing Map for handwritten digits recognition
- Authors: Mohebi, Ehsan , Bagirov, Adil
- Date: 2014
- Type: Text , Journal article
- Relation: Neural Networks Vol. 60, no. (2014), p. 104-118
- Relation: http://purl.org/au-research/grants/arc/DP140103213
- Full Text: false
- Reviewed:
- Description: It is well known that the handwritten digits recognition is a challenging problem. Different classification algorithms have been applied to solve it. Among them, the Self Organizing Maps (SOM) produced promising results. In this paper, first we introduce a Modified SOM for the vector quantization problem with improved initialization process and topology preservation. Then we develop a Convolutional Recursive Modified SOM and apply it to the problem of handwritten digits recognition. The computational results obtained using the well known MNIST dataset demonstrate the superiority of the proposed algorithm over the existing SOM-based algorithms.
A critical examination of the reliability and validity of the SZTPI-15 in British, American and Australian samples
- Authors: McKay, Michael , Worrell, Frank , Temple, Elizabeth , Perry, John , Cole, Jon
- Date: 2014
- Type: Text , Journal article
- Relation: Personality and Individual Differences Vol. 69, no. (October 2014 2014), p. 168-172
- Full Text: false
- Reviewed:
- Description: As an individual difference variable assessing the extent to which attitudes towards past, present and future influence behavior, time perspective is a potentially useful construct. However, its development and utility has been compromised by measurement issues. Recently, a short form of the Zimbardo Time Perspective Inventory (ZTPI), the SZTPI-15 has been suggested to yield valid and reliable scores. Using three independent samples from America, Australia, and the United Kingdom, the present study tested the psychometric properties of SZPTI-15 scores. Confirmatory factor analyses did not support the 5-factor structure and internal consistency estimates for four of the subscales were low. Fit indices obtained from exploratory structural equation modeling were better, suggesting that permitting items to load on multiple factors improved model fit. Correlations with variables shown to be related to ZTPI factors broadly supported the concurrent validity of the SZTPI-15. Results suggest that further psychometric examination of SZTPI-15 scores is required.
- Description: C1
A critical review of robust self-scheduling for generation companies under electricity price uncertainty
- Authors: Vatani, Behdad , Chowdhury, Badrul , Dehghan, Shahab , Amjady, Nima
- Date: 2018
- Type: Text , Journal article
- Relation: International Journal of Electrical Power and Energy Systems Vol. 97, no. (2018), p. 428-439
- Full Text: false
- Reviewed:
- Description: For a generation company trading in an electricity market, efficient control of the financial risks and robustness is as vital as maximizing profit. A robust approach is preferred since the generation company can obtain an optimal self-schedule considering price volatility as a source of uncertainty. The goal of this paper is to implement and compare different robust approaches such as robust optimization methods with different uncertainty sets, conditional value-at-risk based stochastic programming, and information gap decision theory for self-scheduling of generation companies. Moreover, all robust methods are applied to test cases with different price behaviors in the long-run to demonstrate the performance and features of each method. Finally, the different self-scheduling strategies based on the price data and the generation company's desired robustness level are proposed. © 2017 Elsevier Ltd
A critical review on the development and challenges of concentrated solar power technologies
- Authors: Shahabuddin, M. , Alim, M. , Alam, Tanvir , Mofijur, M. , Ahmed, S. , Perkins, Greg
- Date: 2021
- Type: Text , Journal article , Review
- Relation: Sustainable Energy Technologies and Assessments Vol. 47, no. (2021), p.
- Full Text: false
- Reviewed:
- Description: Solar energy is considered to be one of the most promising renewable and sustainable energy sources. Two key technologies such as photovoltaic and concentrated solar power are mainly used to convert solar radiation, out of which photovoltaic directly converts solar radiation into electricity, while concentrated solar power technology converts solar radiation both into heat and electricity. The key advantages of concentrated solar power technology over photovoltaic is its capability of storing heat energy which can be utilised in the absence of sunlight, overcoming the limitation of the intermittent nature of solar power. Currently, the cost for the concentrated solar power with storage is about 9.0 ¢/kWh (same as commercial photovoltaic system), which is expected to drop at ~5.0 ¢/kWh by 2030. Besides four mainstream concentrated solar power technologies, this paper reviewed the application of concentrated solar power in thermolysis, thermochemical cycle, hydrocarbon cracking, reforming and solar gasification. Based on the literature review, this study has outlined the key challenges and prospects of concentrated solar power technologies. The main challenge in thermolysis is the requirement of very high temperature, while the thermochemical cycle is inefficient. Solar thermal cracking, reforming, and gasification integrate carbonaceous fuel to produce synthesis gas and hydrogen and therefore are not emission-free. The concentrated solar power technologies require further development and cost reductions before they can be scaled up to have a meaningful impact on renewable energy targets towards 2050. © 2021 Elsevier Ltd
A decade of head, neck and facial cricket injury hospitalisations in Victoria, Australia : from 2007/08 to 2016/17
- Authors: Kodikara, Dulan , Plumb, Mandy , Twomey, Dara
- Date: 2020
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 23, no. 12 (2020), p. 1161-1165
- Full Text: false
- Reviewed:
- Description: Objectives: To present an epidemiological profile of hospital-treated head, neck and facial cricket injuries from 2007/08 to 2016/17 in Victoria, Australia. Design: Retrospective analysis of emergency department and hospital admission data. Methods: An analysis of Victorian hospital-treated head, neck and facial cricket injuries of all cricket participants over 5 years old between July 2007 and June 2017. Results: Over the decade, 3907 head, neck, facial (HNF) cricket injuries were treated in Victorian hospitals. The number of HNF cricket injuries substantially increased in the 2014/15 season from 367 to 435 injuries and remained over 400 in the subsequent years. More injuries were reported for male compared to female participants, 3583 compared to 324 injuries. When adjusted for participation in competitive cricket, the injury incidence rate was 1.3 per 1000 participants for males and 0.4 per 1000 participants for females. The 10−14 year age group most frequently required hospital treatment. Open wounds were the most common type of injury (1166, 29.8%) and the main mechanism for HNF cricket injury for this decade was hit/struck/crush (3361, 86.0%). Conclusions: This study provides a novel and current insight of the incidence and details of HNF injuries among cricket participants in Victoria over a decade. It is evident that males and younger participants, regardless of gender, have a higher risk of sustaining a HNF injury. This study provides a solid evidence base for stakeholders in developing strategies to minimise head, neck and facial injuries to make cricket a safe sport for all. © 2020 Sports Medicine Australia
A direct time-domain procedure for the seismic analysis of dam–foundation–reservoir systems using the scaled boundary finite element method
- Authors: Qu, Yanling , Chen, Denghong , Liu, Lei , Ooi, Ean Tat , Eisenträger, Sascha , Song, Chongmin
- Date: 2021
- Type: Text , Journal article
- Relation: Computers and Geotechnics Vol. 138, no. (2021), p.
- Full Text: false
- Reviewed:
- Description: In this paper, a direct time-domain procedure for the seismic analysis of dam–reservoir–foundation interactions is presented based on the scaled boundary finite element method (SBFEM). The SBFEM is a semi-analytical method and requires the discretization of boundary only. The geometric complexity in the bounded dam–reservoir–foundation system is easily handled in the SBFEM using quadtree meshes where each structural component can be discretized independently. The elastic wave fields in the unbounded foundation are rigorously captured through SBFE solutions in terms of displacement unit-impulse response functions, while the acoustic wave propagation in the semi-infinite reservoir is modelled by the SBFE-based doubly asymptotic open boundary. The input of seismic excitations is addressed by incorporating the Domain Reduction Method (DRM) into the SBFEM. Cracks are modelled efficiently and accurately by combining the SBFEM and quadtree meshes. The accuracy and efficiency of the proposed methodology is investigated by studying several benchmarks, Pine Flat dam and Jin'anqiao dam. © 2021 Elsevier Ltd
A framework for data privacy and security accountability in data breach communications
- Authors: Thomas, Louise , Gondal, Iqbal , Oseni, Taiwo , Firmin, Sally
- Date: 2022
- Type: Text , Journal article
- Relation: Computers and Security Vol. 116, no. (2022), p.
- Full Text: false
- Reviewed:
- Description: Organisations need to take steps to protect the privacy and security of the personal information they hold. However, when data is breached, how do individuals know whether the organisation took reasonable steps to protect their data? When breached organisations notify affected individuals, this communication is likely to be one of the few windows into the incident from the outside and can become an important artefact for research. This desktop study aimed to consider the extent to which publicly available Australian data breach communications reflect data privacy and security best practices. This paper presents a brief review of literature and government guidance on data security and privacy best practices, along with the results of a qualitative content analysis of 33 publicly available Australian data breach communications. This analysis illustrated that there was little reflection of data privacy and security practices. Literature, government guidance and the content analysis were used to inform and develop a new voluntary framework for organisations. This consists of a series of evaluation questions divided into two broad categories: responsible data management and responsible portrayal of the breach. The framework has the potential to help organisations plan the inclusion of data privacy and security management aspects in their data breach communications. This could assist organisations to address their legal and ethical responsibility to account for their actions in managing privacy and security of the personal data they hold. © 2022
A hydrogen supply-chain model powering Australian isolated communities
- Authors: Hasan, Tanvir , Hassan, Nur , Shah, Rakibuzzaman , Emami, Kianoush , Anderson, Jake
- Date: 2023
- Type: Text , Journal article
- Relation: Energy Reports Vol. 9, no. (2023), p. 209-214
- Full Text:
- Reviewed:
- Description: This article proposes a supply chain-based green hydrogen microgrid modelling for a number of remote Australian communities. Green hydrogen can be used as an emissions-free fuel source for electricity generation in places where large-scale renewable energy production is impossible due to land availability, population, or government regulations. This research focuses on the Torres Strait Island communities in northern Australia, where the transition from diesel to renewable electricity generation is difficult due to very limited land availability on most islands. Due to geographical constraints, low population and smaller electrical load, the green hydrogen needs to be sourced from somewhere else. This research presents a green hydrogen supply chain model that leverages the land availability of one island to produce hydrogen to supply other island communities. In addition, this research presents a model of producing and transporting green hydrogen while supplying cheaper electricity to the communities at focus. The study has used a transitional scenario planning approach and the HOMER simulation platform to find the least-cost solution. Based on the results, a levelised cost of energy range of AU$0.42 and AU$0.44 was found. With the help of a green hydrogen supply chain, CO2 emissions at the selected sites could be cut by 90 %. This study can be used as a guide for small clustered communities that could not support or justify large-scale renewable generation facilities but need more opportunities to install renewable generation. © 2023
A lateral strain plasticity model for FRP confined concrete
- Authors: Piscesa, Bambang , Attard, Mario , Samani, Ali Khajeh
- Date: 2016
- Type: Text , Journal article
- Relation: Composite Structures Vol. 158, no. (2016), p. 160-174
- Full Text: false
- Reviewed:
- Description: This paper presents a plasticity constitutive formulation for actively and passively confined concrete. The loading surface is based on Menetrey and Willam's model with an additional frictional driver parameter. The frictional driver parameter controls the prediction of the peak stress and the residual stress level. The proposed flow rule has a plastic dilation rate control parameter which is a function of the restraining device or the local lateral modulus. A non-constant plastic dilation rate formulation is proposed to improve the prediction of the lateral strain behaviour of concrete. The proposed plastic dilation rate formulation is able to model plastic volumetric compaction caused by the use of very stiff confining devices, as well as the initial plastic compaction after the onset of localized cracking. Furthermore, the formulation is able to distinguish between active and passive confinement by monitoring the local lateral modulus. The accuracy of the proposed plastic dilation rate formulation is verified by comparison with experimental results for specimens subjected to either active or passive confinement from a variety of concrete strengths. The comparison between the proposed plasticity model and the experimental results for concrete under passive confinement (specimens with FRP confining material) was excellent. © 2016
A lightweight cyber security framework with context-awareness for pervasive computing environments
- Authors: Al-Muhtadi, Jalal , Saleem, Kashif , Al-Rabiaah, Sumaya , Imran, Muhammad , Gawanmeh, Amjad , Rodrigues, Joel
- Date: 2021
- Type: Text , Journal article
- Relation: Sustainable Cities and Society Vol. 66, no. (2021), p.
- Full Text: false
- Reviewed:
- Description: Internet of things (IoT) plays a key role in enabling smart sustainable cities. Pervasive computing over the IoT platform makes life more convenient by embedding sensors based on context-aware computing devices in the physical environment for the ubiquitous availability of computing resources. The sensors gather contextual information from the physical world and transmit it to receivers as per requirements or in case of environmental changes, such as temperature and humidity. However, the combination of dynamic operation and the need to handle sensitive and private data make the pervasive computing environment and IoT devices vulnerable to numerous attacks. Smart environments require a maximum level of safety assurance, such as trusted context producers and customers, which should protect sensitive information from exposure or monitoring. This paper discusses the major cyber threats in smart environments and proposes a novel lightweight security framework that authenticates and maintains the context providers and receivers. The cloud environment is adopted for user authentication at the user layer to implement access control and role assignment. Finally, the proposed security framework is implemented in the IBM cloud platform with six devices to evaluate its efficiency, sustainability, and secure communication. © 2020 Elsevier Ltd