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Experimental and numerical investigation of mixed mode fracture of high-performance grouting materials based on peridynamics

- Yao, Jiaxu, Chen, Tao, Chen, Ke, Yuan, Guokai, Xiao, Zhigang

  • Authors: Yao, Jiaxu , Chen, Tao , Chen, Ke , Yuan, Guokai , Xiao, Zhigang
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Fatigue and Fracture of Engineering Materials and Structures Vol. 46, no. 9 (2023), p. 3225-3243
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  • Description: This paper investigates the fracture behavior of high-performance grouting materials in the grouted connection section of marine structures, where they are subjected to complex stress states. This study utilizes a combination of experimental and numerical simulation methods to establish a reliable numerical simulation technique for the fracture process of high-performance grouting materials. The mixed mode fracture behavior is analyzed using six different types of specimens, and the strain contour is analyzed using the Digital Image Correlation technique. An extended peridynamics model is proposed for the numerical simulation, which adopts a fracture criterion based on strain energy density. The accuracy of the model is verified qualitatively and quantitatively, and the simulation results are consistent with the experiments. Overall, this study provides insights into the fracture behavior of high-performance grouting materials in complex stress states and presents a reliable numerical simulation technique for the fracture process. © 2023 John Wiley & Sons Ltd.

Experimental study on cyclic simple shear behaviour of predominantly dilative silica sand

- Baghbani, Abolfazl, Costa, Susanga, O’Kelly, Brendan, Soltani, Amin, Barzegar, Milad

  • Authors: Baghbani, Abolfazl , Costa, Susanga , O’Kelly, Brendan , Soltani, Amin , Barzegar, Milad
  • Date: 2023
  • Type: Text , Journal article
  • Relation: International Journal of Geotechnical Engineering Vol. 17, no. 1 (2023), p. 91-105
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  • Description: This study investigated the cyclic behaviour of a severe dilative silica sand from Rudsar, Northern Iran, through simple shear tests. For this purpose, monotonic (constant volume/vertical stress) and cyclic (constant vertical stress) tests were performed on moist sand specimens prepared at initial relative densities of 20–60%, vertical stresses of 100–300 kPa, and cyclic stress ratios of CSR = 0.20, 0.25 and 0.30. These also included bender element tests to determine the small-strain shear modulus G max. An increase in initial relative density, vertical stress and number of loading cycles led to a nonlinear increase in the secant shear modulus G sec, while the opposite was observed for increasing CSR. Moreover, increasing CSR improved the damping ratio, whereas increasing the initial relative density, vertical stress and/or number of loading cycles had negative effects on the damping ratio. Finally, the bender element test results showed that G max increased for increasing vertical stress and initial relative density. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

Exploration of associations between occupational exposures and current adult eczema

- Lopez, Diego, Alif, Sheikh, Dharmage, Shyamali, Lodge, Caroline, Bui, Dinh, Le Moual, Nicole, Waidyatillake, Nilakshi, Su, John, Abramson, Michael, Walters, E., Hamilton, Garun, Bowatte, Gayan, Erbas, Bircan, Benke, Geza, Perret, Jennifer, Lowe, Adrian

  • Authors: Lopez, Diego , Alif, Sheikh , Dharmage, Shyamali , Lodge, Caroline , Bui, Dinh , Le Moual, Nicole , Waidyatillake, Nilakshi , Su, John , Abramson, Michael , Walters, E. , Hamilton, Garun , Bowatte, Gayan , Erbas, Bircan , Benke, Geza , Perret, Jennifer , Lowe, Adrian
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Occupational and Environmental Medicine Vol. 80, no. 10 (2023), p. 564-571
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  • Description: Objectives There is a scarcity of evidence on occupational exposures that may increase eczema in adults. We aimed to investigate potential associations between occupational exposures and eczema in middle-aged adults. Methods A lifetime work history calendar was collected from the Tasmanian Longitudinal Health Study participants when they were at age 53. Their work history was collated with the occupational asthma-specific job exposure matrix to define ever-exposure and cumulative exposure unit-years since no eczema job exposure matrix is available. Eczema was determined using the report of flexural rash that was coming and going for at least 6 months in the last 12 months. Skin prick tests were used to further subgroup eczema and atopic eczema (AE) or non-AE (NAE). Logistic and multinomial regression models were used to investigate the associations. Results Eczema prevalence was 9.1%. Current occupational exposure to animals (adjusted OR, aOR=3.06 (95% CI 1.43 to 6.58)), storage mites (aOR=2.96 (95% CI 1.38 to 6.34)) and endotoxin (aOR=1.95 (95% CI 1.04 to 3.64)) were associated with increased risk of current eczema. Furthermore, increased odds of NAE were associated with current exposure to animals (aOR=5.60 (95% CI 1.45 to 21.7)) and storage mites (aOR=5.63 (95% CI 1.45 to 21.9)). Current exposures to isocyanates (aOR=5.27 (95% CI 1.17 to 23.7)) and acrylates (aOR=8.41 (95% CI 1.60 to 44.3)) were associated with AE. There was no evidence of associations between cumulative exposures and eczema prevalence. Cumulative exposure to metalworking fluids (aOR=1.10 (95% CI 1.01 to 1.22)) was associated with NAE and acrylates (aOR=1.24 (95% CI 1.04 to 1.46)) with AE. Conclusions In this exploratory assessment, multiple occupational exposures were associated with current eczema in middle-aged adults. Raising awareness and limiting these exposures during an individual's productive working life will likely have various health benefits, including reducing eczema prevalence. © Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.

Exploration of the preliminary effectiveness and acceptability of a self-help digital intervention to support benzodiazepine cessation and improve mental health and wellbeing : a one-group pilot trial

- Klein, Britt, Oldenhof, Erin, Nguyen, Huy, Schattner, Peter, Shandley, Kerrie

  • Authors: Klein, Britt , Oldenhof, Erin , Nguyen, Huy , Schattner, Peter , Shandley, Kerrie
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Journal of Behavioral and Cognitive Therapy Vol. 33, no. 3 (2023), p. 179-193
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  • Description: Introduction: Benzodiazepines (BDZs) are often inappropriately prescribed to manage anxiety and insomnia for longer-term use, despite guidelines recommending short-term use (i.e., <4 weeks). A range of harms can occur rapidly with regular use, and dependence can make stopping BDZs challenging. Evidence shows that a combination of BDZ tapering and psychological support are effective interventions, yet are not widely accessible. Methods: This was a one-group pilot trial of a 6-week fully automated self-help BDZ digital intervention (‘BDZ digital health’), providing guidance on how to safely taper BDZs as well as psychological support. The trial was undertaken with Australian adults considering a reduction and/or withdrawal from their BDZ (N = 43). Participants were assessed at pre-intervention (Week 0), during intervention (Week 3), post-intervention (Week 6), and at a 3- and 6-month follow-up (Week 18 and 30 respectively). Results: Reductions in BDZ use and self-reported dependency were observed over the course of the intervention. Significant symptom reductions in anxiety, insomnia, depression, psychological distress, and emotional dysregulation, as well as improvements in mental wellbeing and quality of life were observed when looking across all timepoints. However, the specific assessment timepoint changes for depression and psychological distress did not reach significance from the pre- to post-intervention timepoint. The intervention acceptability ratings were in the moderately high to high range. Discussion: The preliminary results of the pilot trial suggest that BDZ digital health is an acceptable and promising self-help digital intervention to assist adults reducing and withdrawing from their BDZs, and to improve their mental health and wellbeing. Trial registration: ACTRN12617000574347 (24/04/2017). © 2023 Association Française de Therapie Comportementale et Cognitive

Exploring greener pathways and catalytic systems for ethylene carbonate production

- Ng, Wei, Minh Loy, Adrian, McManus, David, Gupta, Ashwani, Sarmah, Ajit, Bhattacharya, Sankar

  • Authors: Ng, Wei , Minh Loy, Adrian , McManus, David , Gupta, Ashwani , Sarmah, Ajit , Bhattacharya, Sankar
  • Date: 2023
  • Type: Text , Journal article , Review
  • Relation: ACS Sustainable Chemistry and Engineering Vol. 11, no. 39 (2023), p. 14287-14307
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  • Description: The production of cyclic carbonates is pivotal in carbon capture and utilization (CCU), providing an opportunity to utilize recycled CO2. Ethylene carbonate (EC) holds significance among cyclic carbonates in industrial settings due to its extensive applications in lithium-ion batteries and industrial lubricants and as a precursor for green polycarbonate production. However, the current synthesis of EC relies on toxic, fossil-based epoxide reactants, which poses sustainability challenges. To meet the growing demand for green chemistry, three greener alternative pathways for EC synthesis have been proposed, involving the reaction of carbon-based reactants (CO2, urea, and dimethyl carbonate) with ethylene glycol (EG) derived from biodiesel waste. This Perspective addresses key inquiries surrounding alternative EC synthesis pathways through quantitative and qualitative assessments. Specifically, we elucidate (a) possible sustainable routes, (b) current advances in the first principle of kinetic and operational methods, and (c) differences in reactions from the perspectives of thermodynamics, safety, and greenness of production. Notably, the direct carboxylation of CO2 with EG emerges as a promising green synthesis route, but challenges persist, such as catalyst development and water inhibition. Finally, future prospects for overcoming challenges in the green manufacturing of EC are discussed, providing insights into advancing CCU. © 2023 American Chemical Society.

Exploring public sentiment during COVID-19 : a cross country analysis

- Yu, Shuo, He, Sihan, Cai, Zhen, Lee, Ivan, Naseriparsa, Mehdi, Xia, Feng

  • Authors: Yu, Shuo , He, Sihan , Cai, Zhen , Lee, Ivan , Naseriparsa, Mehdi , Xia, Feng
  • Date: 2023
  • Type: Text , Journal article
  • Relation: IEEE Transactions on Computational Social Systems Vol. 10, no. 3 (2023), p. 1083-1094
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  • Description: COVID-19 has spread all over the world, accounting for countless death and enormous economic loss. Since the World Health Organization (WHO) declared COVID-19 as a pandemic, governments from different countries have made various policies to prevent the pandemic from becoming worse. However, civilian reactions to the pandemic vary when they face similar situations. This behavioral variation creates a challenge when it comes to policy-making. Such differences are generally implicit, hidden in ones' social lives. As a result, it is challenging to analyze such differences when the governments make policies. In this work, we investigate social media posts on Twitter and Weibo in order to effectively explore the difference in reactions across various countries, with the aim to understand national differences. To this end, we employ natural language processing (NLP) methods and Linguistic Inquiry and Word Count (LIWC) tools to process six languages in different countries, including the USA, Germany, France, Italy, the U.K., and China. We provide a comprehensive analysis of public reaction differences from the emotional perspective. Our findings verify that the reactions vary noticeably among various countries for some policies. Therefore, sentiment analysis can significantly influence policy-making. Our work sheds light on the mechanism of detecting the reaction differences in various countries, which can be utilized to conduct effective communication and make appropriate policy decisions. © 2014 IEEE.

Exploring the relationship between testosterone and diabetes within the UK Biobank data

- Oatley, Giles

Exploring the therapeutic effectiveness of genograms in family therapy : a literature review

- Joseph, Bindu, Dickenson, Sarah, McCall, Allira, Roga, Erin

  • Authors: Joseph, Bindu , Dickenson, Sarah , McCall, Allira , Roga, Erin
  • Date: 2023
  • Type: Text , Journal article , Review
  • Relation: Family Journal Vol. 31, no. 1 (2023), p. 21-30
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  • Description: The primary aim of the literature review is to explore the relevant literature on the use and effectiveness of genograms in family therapy. The literature is predominantly related to the use of genograms in various settings and adaptations. There are minimal studies on the effectiveness of genograms as a therapeutic tool in family therapy. Searches were conducted of MEDLINE, EMBASE, CINAHL, SCOPUS and PsycINFO electronic databases. The international review includes all studies, irrespective of study methodology. This review will inform clinicians working in family therapy and other relevant disciplines on the usefulness of genograms as a therapeutic tool, examples of adaptations to the traditional genogram for specific populations and purposes, and, to a lesser extent, the therapeutic effectiveness of genograms in family therapy. The results and discussion will provide insights on the utilisation of genograms, the range of population, gaps in the existing literature and the need for further research. © The Author(s) 2022.

Extensive viewing of children’s entertainment and the potential for incidental learning of early years reading vocabulary : a corpus study

- Green, Clarence

  • Authors: Green, Clarence
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Language and Education Vol. 37, no. 1 (2023), p. 39-53
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  • Description: This study evaluates the potential for incidentally learning early reading vocabulary through the extensive viewing (EV) of children’s movies/television with subtitles. Recent research has investigated how much exposure to important vocabulary EV and extensive reading (ER) provides. Investigations compute the number of repetitions of target vocabulary in corpora designed to represent EV/ER. Curriculum time estimates are then computed based on the time needed to reach vocabulary repetition thresholds linked to incidental learning. This study focuses on an understudied area of EV, namely children’s transition to literacy. It investigates whether early reading vocabulary is available in children’s movies/television, a form of compelling, comprehensible input. Recent research has found vocabulary acquisition gains from EV are enhanced by subtitles. Therefore, this study analyses 743 subtitles from children’s movies (4.8 million words) and 3174 subtitles from children’s series (6.4 million words). Using two recent wordlists representing early reading vocabulary, vocabulary frequency and approximate curriculum time estimates are computed for three thresholds linked to incidental vocabulary acquisition, i.e. 6, 12 and 20 encounters. Results indicate that EV with subtitles could support the development of an oral language vocabulary that contains a pool of words needed for early reading, and provide print exposure to this essential vocabulary. © 2021 Informa UK Limited, trading as Taylor & Francis Group.

External business knowledge transmission : a conceptual framework

- Labas, Alan, Courvisanos, Jerry

  • Authors: Labas, Alan , Courvisanos, Jerry
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Journal of Knowledge Management Vol. 27, no. 8 (2023), p. 2034-2057
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  • Description: Purpose: This study aims to develop an original conceptual framework to guide research into knowledge transmission between professional external knowledge providers and their business clientele. As such, the framework aims to bridge a gap between theory and practice by explicating the processes which affect knowledge transmission and the conversion of knowledge for business application (i.e. knowledge transference). Design/methodology/approach: Key concepts from disciplines of knowledge management, information management, communications, services marketing and business advice are reviewed and integrated into the development of this framework. Underpinned by a critical realist philosophical lens, it provides a robust research guide for examining business advisor knowledge actions in a changing open environment. Findings: This study identifies that the process of knowledge transmission from a source external to a business is more complex than internal knowledge sharing. It addresses this complexity through a knowledge transmission framework, in a research design that is applicable to any methodological paradigm. Real-world application is identified in its applicability for evaluating mechanisms to facilitate knowledge transmission practices of external advisors to small business in regionally isolated communities. Research limitations/implications: The critical realist research methodology allows for causality in knowledge transmission to emerge; however, no assertion is made that the conceptual framework developed needs any particular philosophical paradigm for its application. Instead, what is asserted is that the research framework developed in this paper is specifically suited to the characteristics of external knowledge providers, their tacit knowledge and the businesses they service. Originality/value: This study reconceptualises various theoretical perspectives and develops a sequential process for addressing a research lacuna by specifically examining the processes (or connections) between external business advisor’s knowledge and their advisory actions. With these processes clearly established, the role of external knowledge providers, as knowledge transmitters, deepens the understanding of knowledge transference that up until now has focused typically on internal organisation aspects. © 2022, Emerald Publishing Limited.

EYE : End of year exhibition 2023

  • Date: 2023
  • Type: Text , Artwork
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  • Description: SAT 11 NOV - SAT 25 NOV 2023 This important annual End of Year Exhibition (EYE) showcases work created by graduating students from Federation University’s Bachelor of Visual Arts, Diploma of Graphic Design and Advanced Diploma of Graphic Design, Ballarat, and Bachelor of Fine Arts, Gippsland. For our emerging regional artists, EYE is the culmination of their studies; a showcase of the skills, concepts and level of understanding acquired throughout their degree course. Guided by staff, final year students also assist with the publicity, curation and installation of their work in the gallery environment as a form of art industry practice, professionally exhibiting their work to family, friends and the broader community. Outstanding student achievement awards, generously donated by special award sponsors, will be announced at the opening event at each campus. EYE (Post Office Gallery) Ballarat Formal opening: Fri 10 Nov @ 6pm Open: Wed to Sun 12 - 5pm EYE (Switchback Gallery) Gippsland 9 Nov to 23 Nov 2023 Formal opening: Wed 8 Nov @ 5pm Open: Tue to Thu 10am - 4pm, by appointment Contact: Julie Reed Henderson 03 5122 6050 Image: Sarah Mischker Creatures of Change, 2023 handbuilt glazed mid-fired stoneware H50 x W20 x D20 cm Courtesy the artist

Fabric : the map of our lives

- McDonough, Sharon

Factor structure of the symptoms of alcohol use, gaming, and gambling addictions

- Gomez, Rapson, Stavropoulos, Vasileios, Brown, Taylor, Watson, Shaun

  • Authors: Gomez, Rapson , Stavropoulos, Vasileios , Brown, Taylor , Watson, Shaun
  • Date: 2023
  • Type: Text , Journal article
  • Relation: International Journal of Mental Health and Addiction Vol. 21, no. 5 (2023), p. 3345-3361
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  • Description: Alcohol use, gaming, and gambling addictions are recognized in some form by the major clinical classification symptoms. The current study applied confirmatory factor analysis (CFA) models to compare four different models comprising the symptoms of these addictions. The four models were one-factor (all different types of addiction symptoms loading on a single factor), two-factor (alcohol use and internet/gambling latent factors), three-factor (alcohol use, internet gaming, and gambling symptoms loading only on their respective target latent factors), and bi-factor (alcohol use, internet gaming, and gambling symptoms loading on their respective target latent factor and also on the general addiction factor) models. A general community sample of 968 adults (males = 622, females = 315) completed rating scales with symptoms for the three addictions and also for drug use addiction and distress. Both the three-factor and bi-factor models showed a good fit. However, between these models, only the factors of the three-factor model showed good clarity, reliabilities, and external validities, thereby suggesting that this be the best model to represent ratings of alcohol use, internet gaming, and gambling together. The theoretical, taxonomic, and clinical implications of the findings are discussed. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

Fatigue behavior and digital image correlation monitoring of steel plates with mixed-mode edge cracks repaired with CFRP materials

- Chen, Tao, Ye, Mao, Yao, Cheng, Xiao, Zhigang

  • Authors: Chen, Tao , Ye, Mao , Yao, Cheng , Xiao, Zhigang
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Composite Structures Vol. 304, no. (2023), p.
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  • Description: In recent years, carbon fiber reinforced polymer (CFRP) has been widely used to improve the fatigue behavior of steel structures, while most relevant studies were focused on steel components with mode I cracks. This study aims to investigate the fatigue behavior of steel plates with mixed-mode I/II edge cracks patched with CFRP sheets or plates. A total of eleven specimens were fabricated and tested. A digital image correlation (DIC) system was employed as a non-contact measurement to monitor the fatigue crack propagation. Post-processed displacement fields were used to calculate stress intensity factors (SIFs) near the crack tips. Experimental results showed that double-sided CFRP repairing could significantly improve the fatigue life of edge-cracked specimens, especially those with mode I crack rather than mixed-mode I/II crack. Corresponding finite element (FE) analyses were conducted, and good consistency was achieved with test results of crack growth trajectories and fatigue lives. Further FE analysis considered three parameters: load application angle, CFRP layer number, and initial damage level. © 2022 Elsevier Ltd

Federated learning based trajectory optimization for UAV enabled MEC

- Nehra, Anushka, Consul, Prakhar, Budhiraja, Ishan, Kaur, Gagandeep, Nasser, Nidal, Imran, Muhammad

  • Authors: Nehra, Anushka , Consul, Prakhar , Budhiraja, Ishan , Kaur, Gagandeep , Nasser, Nidal , Imran, Muhammad
  • Date: 2023
  • Type: Text , Conference paper
  • Relation: 2023 IEEE International Conference on Communications, ICC 2023 Vol. 2023-May, p. 1640-1645
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  • Description: We present a moving mobile edge computing architecture in which unmanned aerial vehicles (UAV) serve as an equipment, providing computational power and allowing task offloading from mobile devices (MD). By improving user association, resource allocation, and UAV trajectory, we optimizing the energy consumption of all MDs. Towards that purpose, we provide a Trajectory optimization technique for making real-time choices while considering all the situation of the environment, followed by a DRL-based Trajectory control approach (RLCT). The RLCT approach may be adapted to any UAV takeoff point and can find the solution faster. The FL is introduced to address the Optimization problem in a Semi-distributed DRL technique to deal with UAV trajectory constraints. The proposed FRL approach enables devices to rapidly train the models locally while communicating with a local server to construct a network globally. The simulation results in the result section shows that the proposed technique RLCT and FRL in the paper outperforms the existing methods' while the FRL performs best among all. © 2023 IEEE.

Finding compact and well-separated clusters : clustering using silhouette coefficients

- Bagirov, Adil, Aliguliyev, Ramiz, Sultanova, Nargiz

  • Authors: Bagirov, Adil , Aliguliyev, Ramiz , Sultanova, Nargiz
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Pattern Recognition Vol. 135, no. (2023), p.
  • Relation: http://purl.org/au-research/grants/arc/DP190100580
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  • Description: Finding compact and well-separated clusters in data sets is a challenging task. Most clustering algorithms try to minimize certain clustering objective functions. These functions usually reflect the intra-cluster similarity and inter-cluster dissimilarity. However, the use of such functions alone may not lead to the finding of well-separated and, in some cases, compact clusters. Therefore additional measures, called cluster validity indices, are used to estimate the true number of well-separated and compact clusters. Some of these indices are well-suited to be included into the optimization model of the clustering problem. Silhouette coefficients are among such indices. In this paper, a new optimization model of the clustering problem is developed where the clustering function is used as an objective and silhouette coefficients are used to formulate constraints. Then an algorithm, called CLUSCO (CLustering Using Silhouette COefficients), is designed to construct clusters incrementally. Three schemes are discussed to reduce the computational complexity of the algorithm. Its performance is evaluated using fourteen real-world data sets and compared with that of three state-of-the-art clustering algorithms. Results show that the CLUSCO is able to compute compact clusters which are significantly better separable in comparison with those obtained by other algorithms. © 2022 Elsevier Ltd

Fine-grained image classification based on knowledge distillation

- Liu, Ying, Feng, Hao, Zhang, Weidong, Fang, Jie, Xiao, Peng, Zhang, Dengsheng

  • Authors: Liu, Ying , Feng, Hao , Zhang, Weidong , Fang, Jie , Xiao, Peng , Zhang, Dengsheng
  • Date: 2023
  • Type: Text , Conference paper
  • Relation: 19th International Conference on Natural Computation, Fuzzy Systems and Knowledge Discovery, ICNC-FSKD 2023, Harbin, China, 29-31 July 2023, 2023 19th International Conference on Natural Computation, Fuzzy Systems and Knowledge Discovery (ICNC-FSKD)
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  • Description: Despite the outstanding performance of deep learning-based fine-grained image classification methods, the commonly used models still suffer from high cost of computation and memory Therefore, this paper proposes a mobile-based CNN network that focuses on discriminative features of fine-grained images by embedding a hybrid-domain attention module to achieve higher accuracy in recognition. Specifically, under the premise of reducing network parameters, this paper presents a classification method that combines transfer learning and knowledge distillation to enhance the model's generalization performance and resistance to overfitting. Different knowledge transfer strategies are validated through the experiments in the knowledge distillation process. Mobile models such as SqueezeNet, MobileNetV2, and CBAM MobileNetV2 all demonstrate enhanced performance the knowledge distillation optimization. The proposed method in this paper can be used to develop a lightweight mobile-based CNN model with comparable performance to complex models making it more advantageous in real-life scenarios with limited storage resources and low hardware computation levels. Additionally, the model compression process utilizes only the intermediate features of the original dataset, meeting the confidentiality requirements of the original data in the field of public security. © 2023 IEEE.

Forced oscillation management in a microgrid with distributed converter-based resources using hierarchical deep-learning neural network

- Surinkaew, Tossaporn, Emami, Kianoush, Shah, Rakibuzzaman, Islam, Md Rabiul, Islam, Syed

  • Authors: Surinkaew, Tossaporn , Emami, Kianoush , Shah, Rakibuzzaman , Islam, Md Rabiul , Islam, Syed
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Electric Power Systems Research Vol. 222, no. (2023), p.
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  • Description: In future microgrids (MGs), increasing penetration of distributed converter-based resources (DCRs) has inevitably resulted in the problem of inertia scarcity. The interaction, combination, and/or resonance among converter control loops of DCRs, forced inputs, grid parameters, parasitic elements in networks, and system dominant modes can lead to major forced oscillations (FOs). Previous research works mostly focused the problem of FOs on large-scale power systems. However, the effects of FOs in MGs may be more severe than large-scale power systems due to the lower system inertia. With different characteristics of each DCR, conventional FO management methods applied in large-scale power systems may be ineffective. In this paper, a unified AI-framework named hierarchical deep-learning neural network (HiDeNN) is proposed to effectively handle the FOs in a MG with DCRs. To properly managing the FOs, the HiDeNN is divided into three levels for FO detection, identification, and mitigation, respectively. By considering big data produced from DCRs, the HiDeNN is used to solve complicated FO management problems with a low computational demand. By comparison to conventional FO management methods, performances of the proposed HiDeNN are verified in the modified IEEE 13-node feeder with DCRs under various operating points and FO conditions. © 2023

Forced oscillation suppression using extended virtual synchronous generator in a low-Inertia microgrid

- Kerdphol, Thongchart, Ngamroo, Issarachai, Surinkaew, Tossaporn

  • Authors: Kerdphol, Thongchart , Ngamroo, Issarachai , Surinkaew, Tossaporn
  • Date: 2023
  • Type: Text , Journal article
  • Relation: International Journal of Electrical Power and Energy Systems Vol. 151, no. (2023), p.
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  • Description: Effects of forced oscillations (FOs) in well-damped power systems are relatively smaller than those of microgrids (MGs) in which the severity of the FOs may be intensified by converter interfaced generators (CIGs). According to the distinct system characteristics, the FOs in MGs will be challenging problems in future research topics. Without proper controls of the CIGs, the FOs may be exhibited extremely higher amplitude, resulting in the MG instability. Such influences will be exacerbated in a low-inertia MG, which can trigger critical frequency oscillation and system collapse. This paper introduces an extended virtual synchronous generator (VSG) with virtual forced components to attenuate the dynamic FO effects in the presence of a low-inertia MG. Contrastive scenarios, i.e., periodic, combined, full sine, and high-frequency FOs are conducted to validate the performances of VSG control in both stand-alone and interconnected MG environments. Numerical results verify that the extended VSG control provides promising benefits in a low-inertia MG not only for the sake of MG stability improvement but also the further FO suppression. © 2023 Elsevier Ltd

Formal verification of fraud-resilience in a crowdsourcing consensus protocol

- Afzaal, Hamra, Imran, Muhammad, Janjua, Muhammad

  • Authors: Afzaal, Hamra , Imran, Muhammad , Janjua, Muhammad
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Computers & security Vol. 131, no. (2023), p. 103290
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  • Description: •A Trust and Transactions Chain consensus protocol is proposed for a blockchain-based crowdsourcing system.•Communicating Sequential Programs language is utilized for the formal modeling of the proposed consensus protocol.•The properties of no sybil attack, no eclipse attack, and fraud-resilience are defined through Linear Temporal Logic.•Model checking is employed to ensure the correctness of the proposed consensus protocol.•The formal verification is performed by giving the formal model and properties as input to the Process Analysis Toolkit. [Display omitted] Crowdsourcing has emerged as a promising computing paradigm that utilizes human intelligence to achieve complex tasks, but it encounters several security and trust issues. Blockchain is a potential technology that can resolve most of these issues, however, it is difficult to find an appropriate consensus protocol applicable to crowdsourcing systems. Therefore, this work presents a Trust and Transactions Chain (TTC) consensus protocol built upon blockchain technology. It selects a trusted leader and validators considering a trust model which depends on deposit ratio, block generation and validation rate, and waiting rate. The TTC protocol addresses the main challenge of ensuring correctness related to critical systems of crowdsourcing which has extreme significance as their failure can result in disastrous consequences. This work is primarily focused on fraud-resilience avoiding double-spending attack. It also deals with sybil and eclipse attacks. Model checking is exploited because it is effective and automatic to conduct formal verification. The TTC protocol is formally modeled utilizing Communicating Sequential Programs, and the fraud-resilience property is specified using Linear Temporal Logic. The verification of the model is done using Process Analysis Toolkit that takes the formal model and specified properties as input to inspect the properties’ satisfaction or violation. The results of the formal verification are analyzed with respect to the verification time and the number of visited states.