Differential associations of hypoxia, sleep fragmentation, and depressive symptoms with cognitive dysfunction in obstructive sleep apnea
- Alomri, Ridwan, Kennedy, Gerard, Wali, Siraj, Ahejaili, Faris, Robinson, Stephen
- Authors: Alomri, Ridwan , Kennedy, Gerard , Wali, Siraj , Ahejaili, Faris , Robinson, Stephen
- Date: 2021
- Type: Text , Journal article
- Relation: Sleep Vol. 44, no. 4 (2021), p.
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- Description: Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete cessation of breathing during sleep and increased effort to breathe. This study examined patients who underwent overnight polysomnographic studies in a major sleep laboratory in Saudi Arabia. The study aimed to determine the extent to which intermittent hypoxia, sleep disruption, and depressive symptoms are independently associated with cognitive impairments in OSA. In the sample of 90 participants, 14 had no OSA, 30 mild OSA, 23 moderate OSA, and 23 severe OSA. The findings revealed that hypoxia and sleep fragmentation are independently associated with impairments of sustained attention and reaction time (RT). Sleep fragmentation, but not hypoxia, was independently associated with impairments in visuospatial deficits. Depressive symptoms were independently associated with impairments in the domains of sustained attention, RT, visuospatial ability, and semantic and episodic autobiographical memories. Since the depressive symptoms are independent of hypoxia and sleep fragmentation, effective reversal of cognitive impairment in OSA may require treatment interventions that target each of these factors. © Sleep Research Society 2020. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.
- Authors: Alomri, Ridwan , Kennedy, Gerard , Wali, Siraj , Ahejaili, Faris , Robinson, Stephen
- Date: 2021
- Type: Text , Journal article
- Relation: Sleep Vol. 44, no. 4 (2021), p.
- Full Text:
- Reviewed:
- Description: Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete cessation of breathing during sleep and increased effort to breathe. This study examined patients who underwent overnight polysomnographic studies in a major sleep laboratory in Saudi Arabia. The study aimed to determine the extent to which intermittent hypoxia, sleep disruption, and depressive symptoms are independently associated with cognitive impairments in OSA. In the sample of 90 participants, 14 had no OSA, 30 mild OSA, 23 moderate OSA, and 23 severe OSA. The findings revealed that hypoxia and sleep fragmentation are independently associated with impairments of sustained attention and reaction time (RT). Sleep fragmentation, but not hypoxia, was independently associated with impairments in visuospatial deficits. Depressive symptoms were independently associated with impairments in the domains of sustained attention, RT, visuospatial ability, and semantic and episodic autobiographical memories. Since the depressive symptoms are independent of hypoxia and sleep fragmentation, effective reversal of cognitive impairment in OSA may require treatment interventions that target each of these factors. © Sleep Research Society 2020. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.
Triple Ps and Cs to solve the trouble of transition : A new theoretical model
- Alonaizi, Nafi, Paliadelis, Penny
- Authors: Alonaizi, Nafi , Paliadelis, Penny
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Health Specialties Vol. 3, no. 4 (2015), p. 216-223
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- Description: Aims: Aim of the study was to explore the experiences of interns and preceptors to develop a rich conceptual understanding of their experiences during the internship. Settings and Design: Purposeful sampling was used to recruit 22 interns and 11 preceptors during an internship program at a tertiary public hospital in Riyadh. Methods: We used qualitative research based on a phenomenological approach. The data was collected through semistructured interviews. Data Analysis: Interviews were transcribed verbatim and analysed concurrently using thematic analysis. Results: The internship program had a positive impact on interns and their preceptors. However, both groups reported negative issues related to their preparations (training) and emphasised the need for better cooperation between education and practical healthcare services. Conclusions: The findings lead the researchers to develop a new model for clinical education, future healthcare professionals and those who assist them during the internship, “The Triple Ps and Cs to solve the trouble of transition”.
- Authors: Alonaizi, Nafi , Paliadelis, Penny
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Health Specialties Vol. 3, no. 4 (2015), p. 216-223
- Full Text:
- Reviewed:
- Description: Aims: Aim of the study was to explore the experiences of interns and preceptors to develop a rich conceptual understanding of their experiences during the internship. Settings and Design: Purposeful sampling was used to recruit 22 interns and 11 preceptors during an internship program at a tertiary public hospital in Riyadh. Methods: We used qualitative research based on a phenomenological approach. The data was collected through semistructured interviews. Data Analysis: Interviews were transcribed verbatim and analysed concurrently using thematic analysis. Results: The internship program had a positive impact on interns and their preceptors. However, both groups reported negative issues related to their preparations (training) and emphasised the need for better cooperation between education and practical healthcare services. Conclusions: The findings lead the researchers to develop a new model for clinical education, future healthcare professionals and those who assist them during the internship, “The Triple Ps and Cs to solve the trouble of transition”.
Fitting Voronoi diagrams to planar tesselations
- Aloupis, Greg, Pérez-Rosés, Hebert, Pineda-Villavicencio, Guillermo, Taslakian, Perouz, Trinchet-Almaguer, Dannier
- Authors: Aloupis, Greg , Pérez-Rosés, Hebert , Pineda-Villavicencio, Guillermo , Taslakian, Perouz , Trinchet-Almaguer, Dannier
- Date: 2013
- Type: Text , Conference paper
- Relation: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Vol. 8288 LNCS, p. 349-361
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- Description: Given a tesselation of the plane, defined by a planar straight-line graph G, we want to find a minimal set S of points in the plane, such that the Voronoi diagram associated with S 'fits' G. This is the Generalized Inverse Voronoi Problem (GIVP), defined in [12] and rediscovered recently in [3]. Here we give an algorithm that solves this problem with a number of points that is linear in the size of G, assuming that the smallest angle in G is constant. © 2013 Springer-Verlag.
- Authors: Aloupis, Greg , Pérez-Rosés, Hebert , Pineda-Villavicencio, Guillermo , Taslakian, Perouz , Trinchet-Almaguer, Dannier
- Date: 2013
- Type: Text , Conference paper
- Relation: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) Vol. 8288 LNCS, p. 349-361
- Full Text:
- Reviewed:
- Description: Given a tesselation of the plane, defined by a planar straight-line graph G, we want to find a minimal set S of points in the plane, such that the Voronoi diagram associated with S 'fits' G. This is the Generalized Inverse Voronoi Problem (GIVP), defined in [12] and rediscovered recently in [3]. Here we give an algorithm that solves this problem with a number of points that is linear in the size of G, assuming that the smallest angle in G is constant. © 2013 Springer-Verlag.
Evidence of subdivisions on evolutionary timescales in a large, declining marsupial distributed across a phylogeographic barrier
- Alpers, Deryn, Walker, Faith, Taylor, Andrea, Sunnucks, Paul, Bellman, Steven, Hansen, Birgita, Sherwin, William
- Authors: Alpers, Deryn , Walker, Faith , Taylor, Andrea , Sunnucks, Paul , Bellman, Steven , Hansen, Birgita , Sherwin, William
- Date: 2016
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 11, no. 10 (2016), p. 1-22
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- Description: Major prehistoric forces, such as the climatic shifts of the Pleistocene, can remain visible in a species' population genetics. Inference of refuges via genetic tools is useful for conservation management as it can identify populations whose preservation may help retain a species' adaptive potential. Such investigation is needed for Australia's southern hairy-nosed wombat (Lasiorhinus latifrons), whose conservation status has recently deteriorated, and whose phylogeographic history during the Pleistocene may be atypical compared to other species. Its contemporary range spans approximately 2000 km of diverse habitat on either side of the Spencer Gulf, which was a land bridge during periods of Pleistocene aridity that may have allowed for migration circumventing the arid Eyrean barrier. We sampled from animals in nearly all known sites within the species' current distribution, mainly using non-invasive methods, and employed nuclear and mitochondrial DNA analyses to assess alternative scenarios for Pleistocene impacts on population structure. We found evidence for mildly differentiated populations at the range extremes on either side of Spencer Gulf, with secondary contact between locations neighbouring each side of the barrier. These extreme western and eastern regions, and four other regions in between, were genetically distinct in genotypic clustering analyses. Estimates indicate modest, but complex gene flow patterns among some of these regions, in some cases possibly restricted for several thousand years. Prior to this study there was little information to aid risk assessment and prioritization of conservation interventions facilitating gene flow among populations of this species. The contributions of this study to that issue are outlined. © 2016 Alpers et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
- Authors: Alpers, Deryn , Walker, Faith , Taylor, Andrea , Sunnucks, Paul , Bellman, Steven , Hansen, Birgita , Sherwin, William
- Date: 2016
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 11, no. 10 (2016), p. 1-22
- Full Text:
- Reviewed:
- Description: Major prehistoric forces, such as the climatic shifts of the Pleistocene, can remain visible in a species' population genetics. Inference of refuges via genetic tools is useful for conservation management as it can identify populations whose preservation may help retain a species' adaptive potential. Such investigation is needed for Australia's southern hairy-nosed wombat (Lasiorhinus latifrons), whose conservation status has recently deteriorated, and whose phylogeographic history during the Pleistocene may be atypical compared to other species. Its contemporary range spans approximately 2000 km of diverse habitat on either side of the Spencer Gulf, which was a land bridge during periods of Pleistocene aridity that may have allowed for migration circumventing the arid Eyrean barrier. We sampled from animals in nearly all known sites within the species' current distribution, mainly using non-invasive methods, and employed nuclear and mitochondrial DNA analyses to assess alternative scenarios for Pleistocene impacts on population structure. We found evidence for mildly differentiated populations at the range extremes on either side of Spencer Gulf, with secondary contact between locations neighbouring each side of the barrier. These extreme western and eastern regions, and four other regions in between, were genetically distinct in genotypic clustering analyses. Estimates indicate modest, but complex gene flow patterns among some of these regions, in some cases possibly restricted for several thousand years. Prior to this study there was little information to aid risk assessment and prioritization of conservation interventions facilitating gene flow among populations of this species. The contributions of this study to that issue are outlined. © 2016 Alpers et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Organisational barriers to effective pain management amongst oncology nurses in Saudi Arabia
- Alqahtani, Mohammed, Jones, Linda, Holroyd, Eleanor
- Authors: Alqahtani, Mohammed , Jones, Linda , Holroyd, Eleanor
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Hospital Administration Vol. 5, no. 1 (2015), p. 81-89
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- Description: Cancer pain is a multi-dimensional syndrome with a combination of acute and chronic pain that causes physical, psycho-social, behavioural, emotional and spiritual problems resulting in adverse effects on patients’ quality of life. Nurses need to be well prepared with knowledge on pain assessment and management techniques in oncology units, due to their vital role in the decision-making process regarding pain management. However, limited research has been conducted regarding nurses’ barriers regarding pain management in oncology units, especially in Saudi Arabia. The overall aim of this study was to explore the nurses’ perceived barriers that hinder the delivery of effective pain management to cancer patients. Five focus group discussions were conducted using a purposive sampling of six to eight nurses in each group, with a total of 35 oncology nurses. The results of focus group analysis revealed two main thematic categories with associated sub themes, being nurses’ workloads, and the absence of health team collaboration. This study provides an increased awareness of the barriers that may hinder the efficacy of pain management provided to cancer patients in Saudi Arabia context. Significant implications will benefit nursing practice, administration and education, in addition to identifying potential future research.
- Authors: Alqahtani, Mohammed , Jones, Linda , Holroyd, Eleanor
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Hospital Administration Vol. 5, no. 1 (2015), p. 81-89
- Full Text:
- Reviewed:
- Description: Cancer pain is a multi-dimensional syndrome with a combination of acute and chronic pain that causes physical, psycho-social, behavioural, emotional and spiritual problems resulting in adverse effects on patients’ quality of life. Nurses need to be well prepared with knowledge on pain assessment and management techniques in oncology units, due to their vital role in the decision-making process regarding pain management. However, limited research has been conducted regarding nurses’ barriers regarding pain management in oncology units, especially in Saudi Arabia. The overall aim of this study was to explore the nurses’ perceived barriers that hinder the delivery of effective pain management to cancer patients. Five focus group discussions were conducted using a purposive sampling of six to eight nurses in each group, with a total of 35 oncology nurses. The results of focus group analysis revealed two main thematic categories with associated sub themes, being nurses’ workloads, and the absence of health team collaboration. This study provides an increased awareness of the barriers that may hinder the efficacy of pain management provided to cancer patients in Saudi Arabia context. Significant implications will benefit nursing practice, administration and education, in addition to identifying potential future research.
A robust consistency model of crowd workers in text labeling tasks
- Alqershi, Fattoh, Al-Qurishi, Muhammad, Aksoy, Mehmet, Alrubaian, Majed, Imran, Muhammad
- Authors: Alqershi, Fattoh , Al-Qurishi, Muhammad , Aksoy, Mehmet , Alrubaian, Majed , Imran, Muhammad
- Date: 2020
- Type: Text , Journal article
- Relation: IEEE Access Vol. 8, no. (2020), p. 168381-168393
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- Description: Crowdsourcing is a popular human-based model to acquire labeled data. Despite its ability to generate huge amounts of labelled data at moderate costs, it is susceptible to low quality labels. This can happen through unintentional or intentional errors by the crowd workers. Consistency is an important attribute of reliability. It is a practical metric that evaluates a crowd workers' reliability based on their ability to conform to themselves by yielding the same output when repeatedly given a particular input. Consistency has not yet been sufficiently explored in the literature. In this work, we propose a novel consistency model based on the pairwise comparisons method. We apply this model on unpaid workers. We measure the workers' consistency on tasks of labeling political text-based claims and study the effects of different duplicate task characteristics on their consistency. Our results show that the proposed model outperforms the current state-of-the-art models in terms of accuracy. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/
- Authors: Alqershi, Fattoh , Al-Qurishi, Muhammad , Aksoy, Mehmet , Alrubaian, Majed , Imran, Muhammad
- Date: 2020
- Type: Text , Journal article
- Relation: IEEE Access Vol. 8, no. (2020), p. 168381-168393
- Full Text:
- Reviewed:
- Description: Crowdsourcing is a popular human-based model to acquire labeled data. Despite its ability to generate huge amounts of labelled data at moderate costs, it is susceptible to low quality labels. This can happen through unintentional or intentional errors by the crowd workers. Consistency is an important attribute of reliability. It is a practical metric that evaluates a crowd workers' reliability based on their ability to conform to themselves by yielding the same output when repeatedly given a particular input. Consistency has not yet been sufficiently explored in the literature. In this work, we propose a novel consistency model based on the pairwise comparisons method. We apply this model on unpaid workers. We measure the workers' consistency on tasks of labeling political text-based claims and study the effects of different duplicate task characteristics on their consistency. Our results show that the proposed model outperforms the current state-of-the-art models in terms of accuracy. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/
Children and their parent's perceptions of overweight and obesity in Kuwait children
- Alrashidi, Mohammed, Shahwan-Akl, Lina, Jones, Linda, Jones, Katherine, James, Jennifer
- Authors: Alrashidi, Mohammed , Shahwan-Akl, Lina , Jones, Linda , Jones, Katherine , James, Jennifer
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Current Research Vol. 7, no. 8 (2015), p. 19661-19666
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- Description: Background: The prevalence of overweight and obesity among children are a major public health concern internationally. Recognition of overweight and obesity status is an important step to prevent unhealthy weight. This study was designed to assess the prevalence and to explore the perceptions of children and their parents towards overweight and obesity in children. Methods: A cross-sectional study approach was utilized surveying 635 children aged 11 to 14 years (males and females) in 12 randomly selected public schools in Kuwait. Trained nurses performed measurements of children’s height and weight to determine their Body Mass Index.Valid questionnaire were used to assess children and their parent perception of child’s weight. Results: One quarter of the surveyed children 25.5% (N = 162) were overweight. Over one third of the participants 36.5% (N = 232) were classified as obese. The nurses’ measurements did not coincide with the children’s perceptions but were better aligned with parents’ perceptions of overweight and obesity. Conclusion: The results indicated that there is high prevalence of overweight and obesity among Kuwaiti children. Furthermore, both the children and their parents underestimate the child weight status. Health education programs are highly recommended.
- Authors: Alrashidi, Mohammed , Shahwan-Akl, Lina , Jones, Linda , Jones, Katherine , James, Jennifer
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Current Research Vol. 7, no. 8 (2015), p. 19661-19666
- Full Text:
- Reviewed:
- Description: Background: The prevalence of overweight and obesity among children are a major public health concern internationally. Recognition of overweight and obesity status is an important step to prevent unhealthy weight. This study was designed to assess the prevalence and to explore the perceptions of children and their parents towards overweight and obesity in children. Methods: A cross-sectional study approach was utilized surveying 635 children aged 11 to 14 years (males and females) in 12 randomly selected public schools in Kuwait. Trained nurses performed measurements of children’s height and weight to determine their Body Mass Index.Valid questionnaire were used to assess children and their parent perception of child’s weight. Results: One quarter of the surveyed children 25.5% (N = 162) were overweight. Over one third of the participants 36.5% (N = 232) were classified as obese. The nurses’ measurements did not coincide with the children’s perceptions but were better aligned with parents’ perceptions of overweight and obesity. Conclusion: The results indicated that there is high prevalence of overweight and obesity among Kuwaiti children. Furthermore, both the children and their parents underestimate the child weight status. Health education programs are highly recommended.
Contributing factors to childhood overweight and obesity in Kuwait
- Alrashidi, Mohammed, Shahwan-Akl, Lina, James, Jennifer, Jones, Linda
- Authors: Alrashidi, Mohammed , Shahwan-Akl, Lina , James, Jennifer , Jones, Linda
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Health Sciences (IJHS) Vol. 3, no. 1 (2015), p. 133-155
- Full Text:
- Reviewed:
- Description: The increasing prevalence of overweight and obesity in children is a major public health concern in Kuwait. Understanding the contributing factors is key to the development of an effective intervention strategy. This study was designed to identify what factors contribute to overweight and obesity in school-aged children. Method: A cross-sectional study, using questionnaires, was conducted with public intermediate school children (girls and boys) and their parents to elicit information related to the children’s daily lifestyle. A total of 635 children aged 11-14 years and their parents (N=635) were surveyed and children’s height and weight were measured by school nurses to identify their Body Mass Index. Results: When classified by BMI, about one quarter of the children (25.5%) were overweight and over one third (36.5%) were classified as obese. Multiple regression model found that the BMI of the male children increased significantly with respect to age if they had overweight siblings, spent time on sedentary activities, and regularly ate food from fast food restaurants. The BMI of the female children also increased significantly with respect to age, having overweight siblings, eating at fast food restaurants and for every time not actively travelling to school. Conclusion: The rate of childhood overweight and obesity in Kuwait is currently still high, and Kuwaiti children have been found to be leading unhealthy lifestyles. Involving parents as a part of the solution is an important step in promoting a healthy lifestyle.
- Authors: Alrashidi, Mohammed , Shahwan-Akl, Lina , James, Jennifer , Jones, Linda
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Health Sciences (IJHS) Vol. 3, no. 1 (2015), p. 133-155
- Full Text:
- Reviewed:
- Description: The increasing prevalence of overweight and obesity in children is a major public health concern in Kuwait. Understanding the contributing factors is key to the development of an effective intervention strategy. This study was designed to identify what factors contribute to overweight and obesity in school-aged children. Method: A cross-sectional study, using questionnaires, was conducted with public intermediate school children (girls and boys) and their parents to elicit information related to the children’s daily lifestyle. A total of 635 children aged 11-14 years and their parents (N=635) were surveyed and children’s height and weight were measured by school nurses to identify their Body Mass Index. Results: When classified by BMI, about one quarter of the children (25.5%) were overweight and over one third (36.5%) were classified as obese. Multiple regression model found that the BMI of the male children increased significantly with respect to age if they had overweight siblings, spent time on sedentary activities, and regularly ate food from fast food restaurants. The BMI of the female children also increased significantly with respect to age, having overweight siblings, eating at fast food restaurants and for every time not actively travelling to school. Conclusion: The rate of childhood overweight and obesity in Kuwait is currently still high, and Kuwaiti children have been found to be leading unhealthy lifestyles. Involving parents as a part of the solution is an important step in promoting a healthy lifestyle.
Modeling cyclic crack propagation in concrete using the scaled boundary finite element method coupled with the cumulative damage-plasticity constitutive law
- Alrayes, Omar, Könke, Carsten, Ooi, Ean Tat, Hamdia, Khader
- Authors: Alrayes, Omar , Könke, Carsten , Ooi, Ean Tat , Hamdia, Khader
- Date: 2023
- Type: Text , Journal article
- Relation: Materials Vol. 16, no. 2 (2023), p.
- Full Text:
- Reviewed:
- Description: Many concrete structures, such as bridges and wind turbine towers, fail mostly due to the fatigue rapture and bending, where the cracks are initiated and propagate under cyclic loading. Modeling the fracture process zone (FPZ) is essential to understanding the cracking behavior of heterogeneous, quasi-brittle materials such as concrete under monotonic and cyclic actions. The paper aims to present a numerical modeling approach for simulating crack growth using a scaled boundary finite element model (SBFEM). The cohesive traction law is explored to model the stress field under monotonic and cyclic loading conditions. In doing so, a new constitutive law is applied within the cohesive response. The cyclic damage accumulation during loading and unloading is formulated within the thermodynamic framework of the constitutive concrete model. We consider two common problems of three-point bending of a single-edge-notched concrete beam subjected to different loading conditions to validate the developed method. The simulation results show good agreement with experimental test measurements from the literature. The presented analysis can provide a further understanding of crack growth and damage accumulation within the cohesive response, and the SBFEM makes it possible to identify the fracture behavior of cyclic crack propagation in concrete members. © 2023 by the authors.
- Authors: Alrayes, Omar , Könke, Carsten , Ooi, Ean Tat , Hamdia, Khader
- Date: 2023
- Type: Text , Journal article
- Relation: Materials Vol. 16, no. 2 (2023), p.
- Full Text:
- Reviewed:
- Description: Many concrete structures, such as bridges and wind turbine towers, fail mostly due to the fatigue rapture and bending, where the cracks are initiated and propagate under cyclic loading. Modeling the fracture process zone (FPZ) is essential to understanding the cracking behavior of heterogeneous, quasi-brittle materials such as concrete under monotonic and cyclic actions. The paper aims to present a numerical modeling approach for simulating crack growth using a scaled boundary finite element model (SBFEM). The cohesive traction law is explored to model the stress field under monotonic and cyclic loading conditions. In doing so, a new constitutive law is applied within the cohesive response. The cyclic damage accumulation during loading and unloading is formulated within the thermodynamic framework of the constitutive concrete model. We consider two common problems of three-point bending of a single-edge-notched concrete beam subjected to different loading conditions to validate the developed method. The simulation results show good agreement with experimental test measurements from the literature. The presented analysis can provide a further understanding of crack growth and damage accumulation within the cohesive response, and the SBFEM makes it possible to identify the fracture behavior of cyclic crack propagation in concrete members. © 2023 by the authors.
A new global index for short term voltage stability assessment
- Alshareef, Abdulrhman, Shah, Rakibuzzaman, Mithulananthan, Nadarajah, Alzahrani, Saeed
- Authors: Alshareef, Abdulrhman , Shah, Rakibuzzaman , Mithulananthan, Nadarajah , Alzahrani, Saeed
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Access Vol. 9, no. (2021), p. 36114-36124
- Full Text:
- Reviewed:
- Description: The utility scale of non-conventional generators (NCGs), such as wind and photovoltaic (PV) plants, are competitive alternatives to synchronous machines (SMs) for power generation. Higher penetration of NCGs has been respondent of causing several recent incidents leading up to voltage collapse in power systems due to the distinct characteristics of NCGs under different operating conditions. Consequently, the so-called system strength has been reduced with higher NCGs penetration. A number of indices have been developed to quantify system strength from the short-term voltage stability (STVS) perspective. None of the indices capture the overall performances of power systems on dynamic voltage recovery. In this paper, an improvement in one of the STVS indices namely, the Voltage Recovery Index (VRI), is proposed to overcome shortcomings in the original index. Moreover, the improved index is globalized to establish a new index defined as system voltage recovery index (VRIsys) to quantify STVS at the system level. The amended VRI and developed VRIsys are used in systematic simulations to quantify the impact and interaction of various factors that could affect system strength. The assessment was conducted using time-domain simulation with direct connected induction motors (DCIMs) and a proliferation of converter-based technologies on both the generation and load sides, namely, NCGs and Variable Speed Drives (VSDs), respectively. © 2013 IEEE.
- Authors: Alshareef, Abdulrhman , Shah, Rakibuzzaman , Mithulananthan, Nadarajah , Alzahrani, Saeed
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Access Vol. 9, no. (2021), p. 36114-36124
- Full Text:
- Reviewed:
- Description: The utility scale of non-conventional generators (NCGs), such as wind and photovoltaic (PV) plants, are competitive alternatives to synchronous machines (SMs) for power generation. Higher penetration of NCGs has been respondent of causing several recent incidents leading up to voltage collapse in power systems due to the distinct characteristics of NCGs under different operating conditions. Consequently, the so-called system strength has been reduced with higher NCGs penetration. A number of indices have been developed to quantify system strength from the short-term voltage stability (STVS) perspective. None of the indices capture the overall performances of power systems on dynamic voltage recovery. In this paper, an improvement in one of the STVS indices namely, the Voltage Recovery Index (VRI), is proposed to overcome shortcomings in the original index. Moreover, the improved index is globalized to establish a new index defined as system voltage recovery index (VRIsys) to quantify STVS at the system level. The amended VRI and developed VRIsys are used in systematic simulations to quantify the impact and interaction of various factors that could affect system strength. The assessment was conducted using time-domain simulation with direct connected induction motors (DCIMs) and a proliferation of converter-based technologies on both the generation and load sides, namely, NCGs and Variable Speed Drives (VSDs), respectively. © 2013 IEEE.
Impact of PV plant and load models on system strength and voltage recovery of power systems
- Alshareef, Abdulrhman, Shah, Rakibuzzaman, Mithulananthan, Nadarajah
- Authors: Alshareef, Abdulrhman , Shah, Rakibuzzaman , Mithulananthan, Nadarajah
- Date: 2020
- Type: Text , Conference proceedings
- Relation: 2nd International Conference on Smart Power and Internet Energy Systems, SPIES 2020; Bangkok, Thailand; 15th-18th September 2020 p. 263-268
- Full Text:
- Reviewed:
- Description: In recent years, non-conventional inverter-based sources, namely, wind, PV, and others have emerged as excellent alternatives to the traditional synchronous machine for power generation. It has also been reported that the so-called system strength may be reduced with high penetration of non-conventional generations (NCGs). A number of methods have been used to assess system strength which may not reflect the interdependency or reciprocal influence of various factors affecting it. This paper presents a thorough assessment to quantify the implications of and the interaction of various factors affecting system strength, with the voltage recovery index being used as a quantification tool. © 2020 IEEE.
- Authors: Alshareef, Abdulrhman , Shah, Rakibuzzaman , Mithulananthan, Nadarajah
- Date: 2020
- Type: Text , Conference proceedings
- Relation: 2nd International Conference on Smart Power and Internet Energy Systems, SPIES 2020; Bangkok, Thailand; 15th-18th September 2020 p. 263-268
- Full Text:
- Reviewed:
- Description: In recent years, non-conventional inverter-based sources, namely, wind, PV, and others have emerged as excellent alternatives to the traditional synchronous machine for power generation. It has also been reported that the so-called system strength may be reduced with high penetration of non-conventional generations (NCGs). A number of methods have been used to assess system strength which may not reflect the interdependency or reciprocal influence of various factors affecting it. This paper presents a thorough assessment to quantify the implications of and the interaction of various factors affecting system strength, with the voltage recovery index being used as a quantification tool. © 2020 IEEE.
Influence of induction motor in stability of power system with high penetration of large-scale PV
- Alshareef, Abdulrhman, Nadarajah, Mithulananthan, Shah, Rakibuzzaman
- Authors: Alshareef, Abdulrhman , Nadarajah, Mithulananthan , Shah, Rakibuzzaman
- Date: 2020
- Type: Text , Conference proceedings
- Relation: 2nd International Conference on Smart Power and Internet Energy Systems, SPIES 2020; Bangkok, Thailand; 15th-18th September 2020 p. 269-274
- Full Text:
- Reviewed:
- Description: Inverter-Based Energy Resources (IBERs) have become an ordinary portion of the generation mix in power systems. Furthermore, converter-based technology has come to dominate modern motor loads on the consumption side. This transition in components towards accommodating power electronic devices alters the dynamic response of the power system. This paper investigates the impact of these elements on the dynamic stability of the power system. Firstly, this study successes to optimize a suitable model for converter-based motor loads. Secondly, indices of transient and voltage stabilities are used to quantify the strength of the power system at different circumstances incorporating the induction motor loads. Finally, this analysis provides an insight into the mutual interactions between transient and voltage stabilities. It is concluded that converter-based motor loads improve the voltage recovery when compared with direct-connected induction motors. However, the system is vulnerable to transient stability with the proliferation of inverter-based motor loads when IBERs dominant in the generation mix. © 2020 IEEE.
- Authors: Alshareef, Abdulrhman , Nadarajah, Mithulananthan , Shah, Rakibuzzaman
- Date: 2020
- Type: Text , Conference proceedings
- Relation: 2nd International Conference on Smart Power and Internet Energy Systems, SPIES 2020; Bangkok, Thailand; 15th-18th September 2020 p. 269-274
- Full Text:
- Reviewed:
- Description: Inverter-Based Energy Resources (IBERs) have become an ordinary portion of the generation mix in power systems. Furthermore, converter-based technology has come to dominate modern motor loads on the consumption side. This transition in components towards accommodating power electronic devices alters the dynamic response of the power system. This paper investigates the impact of these elements on the dynamic stability of the power system. Firstly, this study successes to optimize a suitable model for converter-based motor loads. Secondly, indices of transient and voltage stabilities are used to quantify the strength of the power system at different circumstances incorporating the induction motor loads. Finally, this analysis provides an insight into the mutual interactions between transient and voltage stabilities. It is concluded that converter-based motor loads improve the voltage recovery when compared with direct-connected induction motors. However, the system is vulnerable to transient stability with the proliferation of inverter-based motor loads when IBERs dominant in the generation mix. © 2020 IEEE.
An analysis of autonomic nervous system fuctioning in panic disorder and its relation to negative affect / Marles E. Alvarenga
- Authors: Alvarenga, Marlies
- Date: 2002
- Type: Text , Thesis , PhD
- Full Text:
- Description: "The present studies investigated the issue of potential explanatory mechanisms for the observed association between panic disorder (PD) and the development of cardiovascular disease (CVD). Specifically, this research aimed to elucidate more clearly the contribution of psychological variables. physical processes and social relations to the onset of cardiopathology."
- Description: Doctor of Clinical Psychology
- Authors: Alvarenga, Marlies
- Date: 2002
- Type: Text , Thesis , PhD
- Full Text:
- Description: "The present studies investigated the issue of potential explanatory mechanisms for the observed association between panic disorder (PD) and the development of cardiovascular disease (CVD). Specifically, this research aimed to elucidate more clearly the contribution of psychological variables. physical processes and social relations to the onset of cardiopathology."
- Description: Doctor of Clinical Psychology
The global burden of adolescent and young adult cancer in 2019 : a systematic analysis for the Global Burden of Disease Study 2019
- Alvarez, Elysia, Force, Lisa, Xu, Rixing, Compton, Kelly, Lu, Dan, Henrikson, Hannah, Kocarnik, Jonathan, Harvey, James, Pennini, Alyssa, Dean, Frances, Fu, Weijia, Vargas, Martina, Keegan, Theresa, Ariffin, Hany, Barr, Ronald, Erdomaeva, Yana, Gunasekera, D. Sanjeeva, John-Akinola, Yetunde, Ketterl, Tyler, Kutluk, Tezer, Malogolowkin, Marcio, Mathur, Prashan, Radhakrishnan, Venkatraman, Ries, Lynn, Rodriguez-Galindo, Carlos, Sagoyan, Garik, Sultan, Iyad, Abbasi, Behzad, Abbasi-Kangevari, Mohsen, Rahman, Monsiur
- Authors: Alvarez, Elysia , Force, Lisa , Xu, Rixing , Compton, Kelly , Lu, Dan , Henrikson, Hannah , Kocarnik, Jonathan , Harvey, James , Pennini, Alyssa , Dean, Frances , Fu, Weijia , Vargas, Martina , Keegan, Theresa , Ariffin, Hany , Barr, Ronald , Erdomaeva, Yana , Gunasekera, D. Sanjeeva , John-Akinola, Yetunde , Ketterl, Tyler , Kutluk, Tezer , Malogolowkin, Marcio , Mathur, Prashan , Radhakrishnan, Venkatraman , Ries, Lynn , Rodriguez-Galindo, Carlos , Sagoyan, Garik , Sultan, Iyad , Abbasi, Behzad , Abbasi-Kangevari, Mohsen , Rahman, Monsiur
- Date: 2022
- Type: Text , Journal article
- Relation: The Lancet Oncology Vol. 23, no. 1 (2022), p. 27-52
- Full Text:
- Reviewed:
- Description: Background: In estimating the global burden of cancer, adolescents and young adults with cancer are often overlooked, despite being a distinct subgroup with unique epidemiology, clinical care needs, and societal impact. Comprehensive estimates of the global cancer burden in adolescents and young adults (aged 15–39 years) are lacking. To address this gap, we analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, with a focus on the outcome of disability-adjusted life-years (DALYs), to inform global cancer control measures in adolescents and young adults. Methods: Using the GBD 2019 methodology, international mortality data were collected from vital registration systems, verbal autopsies, and population-based cancer registry inputs modelled with mortality-to-incidence ratios (MIRs). Incidence was computed with mortality estimates and corresponding MIRs. Prevalence estimates were calculated using modelled survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated as age-specific cancer deaths multiplied by the standard life expectancy at the age of death. The main outcome was DALYs (the sum of YLLs and YLDs). Estimates were presented globally and by Socio-demographic Index (SDI) quintiles (countries ranked and divided into five equal SDI groups), and all estimates were presented with corresponding 95% uncertainty intervals (UIs). For this analysis, we used the age range of 15–39 years to define adolescents and young adults. Findings: There were 1·19 million (95% UI 1·11–1·28) incident cancer cases and 396 000 (370 000–425 000) deaths due to cancer among people aged 15–39 years worldwide in 2019. The highest age-standardised incidence rates occurred in high SDI (59·6 [54·5–65·7] per 100 000 person-years) and high-middle SDI countries (53·2 [48·8–57·9] per 100 000 person-years), while the highest age-standardised mortality rates were in low-middle SDI (14·2 [12·9–15·6] per 100 000 person-years) and middle SDI (13·6 [12·6–14·8] per 100 000 person-years) countries. In 2019, adolescent and young adult cancers contributed 23·5 million (21·9–25·2) DALYs to the global burden of disease, of which 2·7% (1·9–3·6) came from YLDs and 97·3% (96·4–98·1) from YLLs. Cancer was the fourth leading cause of death and tenth leading cause of DALYs in adolescents and young adults globally. Interpretation: Adolescent and young adult cancers contributed substantially to the overall adolescent and young adult disease burden globally in 2019. These results provide new insights into the distribution and magnitude of the adolescent and young adult cancer burden around the world. With notable differences observed across SDI settings, these estimates can inform global and country-level cancer control efforts. Funding: Bill & Melinda Gates Foundation, American Lebanese Syrian Associated Charities, St Baldrick's Foundation, and the National Cancer Institute. © 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. **Please note that there are multiple authors for this article therefore only the name of the first 30 including Federation University Australia affiliate “Rahman, Monsiur" are provided in this record**
- Authors: Alvarez, Elysia , Force, Lisa , Xu, Rixing , Compton, Kelly , Lu, Dan , Henrikson, Hannah , Kocarnik, Jonathan , Harvey, James , Pennini, Alyssa , Dean, Frances , Fu, Weijia , Vargas, Martina , Keegan, Theresa , Ariffin, Hany , Barr, Ronald , Erdomaeva, Yana , Gunasekera, D. Sanjeeva , John-Akinola, Yetunde , Ketterl, Tyler , Kutluk, Tezer , Malogolowkin, Marcio , Mathur, Prashan , Radhakrishnan, Venkatraman , Ries, Lynn , Rodriguez-Galindo, Carlos , Sagoyan, Garik , Sultan, Iyad , Abbasi, Behzad , Abbasi-Kangevari, Mohsen , Rahman, Monsiur
- Date: 2022
- Type: Text , Journal article
- Relation: The Lancet Oncology Vol. 23, no. 1 (2022), p. 27-52
- Full Text:
- Reviewed:
- Description: Background: In estimating the global burden of cancer, adolescents and young adults with cancer are often overlooked, despite being a distinct subgroup with unique epidemiology, clinical care needs, and societal impact. Comprehensive estimates of the global cancer burden in adolescents and young adults (aged 15–39 years) are lacking. To address this gap, we analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, with a focus on the outcome of disability-adjusted life-years (DALYs), to inform global cancer control measures in adolescents and young adults. Methods: Using the GBD 2019 methodology, international mortality data were collected from vital registration systems, verbal autopsies, and population-based cancer registry inputs modelled with mortality-to-incidence ratios (MIRs). Incidence was computed with mortality estimates and corresponding MIRs. Prevalence estimates were calculated using modelled survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated as age-specific cancer deaths multiplied by the standard life expectancy at the age of death. The main outcome was DALYs (the sum of YLLs and YLDs). Estimates were presented globally and by Socio-demographic Index (SDI) quintiles (countries ranked and divided into five equal SDI groups), and all estimates were presented with corresponding 95% uncertainty intervals (UIs). For this analysis, we used the age range of 15–39 years to define adolescents and young adults. Findings: There were 1·19 million (95% UI 1·11–1·28) incident cancer cases and 396 000 (370 000–425 000) deaths due to cancer among people aged 15–39 years worldwide in 2019. The highest age-standardised incidence rates occurred in high SDI (59·6 [54·5–65·7] per 100 000 person-years) and high-middle SDI countries (53·2 [48·8–57·9] per 100 000 person-years), while the highest age-standardised mortality rates were in low-middle SDI (14·2 [12·9–15·6] per 100 000 person-years) and middle SDI (13·6 [12·6–14·8] per 100 000 person-years) countries. In 2019, adolescent and young adult cancers contributed 23·5 million (21·9–25·2) DALYs to the global burden of disease, of which 2·7% (1·9–3·6) came from YLDs and 97·3% (96·4–98·1) from YLLs. Cancer was the fourth leading cause of death and tenth leading cause of DALYs in adolescents and young adults globally. Interpretation: Adolescent and young adult cancers contributed substantially to the overall adolescent and young adult disease burden globally in 2019. These results provide new insights into the distribution and magnitude of the adolescent and young adult cancer burden around the world. With notable differences observed across SDI settings, these estimates can inform global and country-level cancer control efforts. Funding: Bill & Melinda Gates Foundation, American Lebanese Syrian Associated Charities, St Baldrick's Foundation, and the National Cancer Institute. © 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. **Please note that there are multiple authors for this article therefore only the name of the first 30 including Federation University Australia affiliate “Rahman, Monsiur" are provided in this record**
Exploring the Dynamic Voltage Signature of Renewable Rich Weak Power System
- Alzahrani, S., Shah, Rakibuzzaman, Mithulananthan, N.
- Authors: Alzahrani, S. , Shah, Rakibuzzaman , Mithulananthan, N.
- Date: 2020
- Type: Text , Journal article
- Relation: IEEE Access Vol. 8, no. (2020), p. 216529-216542
- Full Text:
- Reviewed:
- Description: Large-scale renewable energy-based power plants are becoming attractive technically and economically for generation mix around the world. Nevertheless, network operation has significantly changed due to the rapid integration of renewable energy in supply side. The integration of more renewable resources, especially inverter-based generation, deteriorates power system resilience to disturbances and substantially affects stable operations. The dynamic voltage stability becomes one of the major concerns for the transmission system operators (TSOs) due to the limited capabilities of inverter-based resources (IBRs). A heavily loaded and stressed renewable rich grid is susceptible to fault-induced delayed voltage recovery. Hence, it is crucial to examine the system response upon disturbances, to understand the voltage signature, to determine the optimal location and sizing of grid-connected IBRs. Moreover, the IBRs fault contribution mechanism investigation is essential in adopting additional grid support devices, control coordination, and the selection of appropriate corrective control schemes. This article utilizes a comprehensive assessment framework to assess power systems' dynamic voltage signature with large-scale PV under different realistic operating conditions. Several indices quantifying load bus voltage recovery have been used to explore the system' s steady-state, transient response, and voltage trajectories. The recovery indices help extricate the signature and influence of IBRs. The proposed framework's applicability is carried out on the New England IEEE-39 bus test system using the DIgSILENT platform. © 2013 IEEE.
- Authors: Alzahrani, S. , Shah, Rakibuzzaman , Mithulananthan, N.
- Date: 2020
- Type: Text , Journal article
- Relation: IEEE Access Vol. 8, no. (2020), p. 216529-216542
- Full Text:
- Reviewed:
- Description: Large-scale renewable energy-based power plants are becoming attractive technically and economically for generation mix around the world. Nevertheless, network operation has significantly changed due to the rapid integration of renewable energy in supply side. The integration of more renewable resources, especially inverter-based generation, deteriorates power system resilience to disturbances and substantially affects stable operations. The dynamic voltage stability becomes one of the major concerns for the transmission system operators (TSOs) due to the limited capabilities of inverter-based resources (IBRs). A heavily loaded and stressed renewable rich grid is susceptible to fault-induced delayed voltage recovery. Hence, it is crucial to examine the system response upon disturbances, to understand the voltage signature, to determine the optimal location and sizing of grid-connected IBRs. Moreover, the IBRs fault contribution mechanism investigation is essential in adopting additional grid support devices, control coordination, and the selection of appropriate corrective control schemes. This article utilizes a comprehensive assessment framework to assess power systems' dynamic voltage signature with large-scale PV under different realistic operating conditions. Several indices quantifying load bus voltage recovery have been used to explore the system' s steady-state, transient response, and voltage trajectories. The recovery indices help extricate the signature and influence of IBRs. The proposed framework's applicability is carried out on the New England IEEE-39 bus test system using the DIgSILENT platform. © 2013 IEEE.
Examination of effective VAr with respect to dynamic voltage stability in renewable rich power grids
- Alzahrani, Saeed, Shah, Rakibuzzaman, Mithulananthan, N.
- Authors: Alzahrani, Saeed , Shah, Rakibuzzaman , Mithulananthan, N.
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Access Vol. 9, no. (2021), p. 75494-75508
- Full Text:
- Reviewed:
- Description: High penetrations of inverter-based renewable resources (IBRs) diminish the resilience that traditional power systems had due to constant research and developments for many years. In particular, dynamic voltage stability becomes one of the major concerns for transmission system operators due to the limited capabilities of IBRs (i.e., voltage and frequency regulation). A heavily loaded renewable-rich network is susceptible to fault-induced delayed voltage recovery (FIDVR) due to insufficient effective reactive power (E-VAr) in power grids. Hence, it is crucial to thoroughly scrutinize each VAr resources' participation in E-VAr under various operating conditions. Moreover, it is essential to investigate the influence of E-VAr on system post-fault performance. The E-VAr investigation would help in determining the optimal location and sizing of grid-connected IBRs and allow more renewable energy integration. Furthermore, it would enrich decision-making about adopting additional grid support devices. In this paper, a comprehensive assessment framework is utilized to assess the E-VAr of a power system with a large-scale photovoltaic power. Plant under different realistic operating conditions. Several indices quantifying the contribution of VAr resources and load bus voltage recovery assists to explore the transient response and voltage trajectories. The recovery indices help have a better understanding of the factors affecting E-VAr. The proposed framework has been tested in the New England (IEEE 39 bus system) through simulation by DIgSILENT Power Factory. © 2013 IEEE.
Examination of effective VAr with respect to dynamic voltage stability in renewable rich power grids
- Authors: Alzahrani, Saeed , Shah, Rakibuzzaman , Mithulananthan, N.
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Access Vol. 9, no. (2021), p. 75494-75508
- Full Text:
- Reviewed:
- Description: High penetrations of inverter-based renewable resources (IBRs) diminish the resilience that traditional power systems had due to constant research and developments for many years. In particular, dynamic voltage stability becomes one of the major concerns for transmission system operators due to the limited capabilities of IBRs (i.e., voltage and frequency regulation). A heavily loaded renewable-rich network is susceptible to fault-induced delayed voltage recovery (FIDVR) due to insufficient effective reactive power (E-VAr) in power grids. Hence, it is crucial to thoroughly scrutinize each VAr resources' participation in E-VAr under various operating conditions. Moreover, it is essential to investigate the influence of E-VAr on system post-fault performance. The E-VAr investigation would help in determining the optimal location and sizing of grid-connected IBRs and allow more renewable energy integration. Furthermore, it would enrich decision-making about adopting additional grid support devices. In this paper, a comprehensive assessment framework is utilized to assess the E-VAr of a power system with a large-scale photovoltaic power. Plant under different realistic operating conditions. Several indices quantifying the contribution of VAr resources and load bus voltage recovery assists to explore the transient response and voltage trajectories. The recovery indices help have a better understanding of the factors affecting E-VAr. The proposed framework has been tested in the New England (IEEE 39 bus system) through simulation by DIgSILENT Power Factory. © 2013 IEEE.
Dynamic voltage signature of large scale PV enriched streesed power system
- Alzahrani, Saeed, Shah, Rakibuzzaman, Mithulananthan, Nadarajah, Sode-Yome, Arthit
- Authors: Alzahrani, Saeed , Shah, Rakibuzzaman , Mithulananthan, Nadarajah , Sode-Yome, Arthit
- Date: 2020
- Type: Text , Conference proceedings
- Relation: 2nd International Conference on Smart Power and Internet Energy Systems, SPIES 2020; Bangkok, Thailand; 15th-18th September 2020 p. 275-280
- Full Text:
- Reviewed:
- Description: Renewable power generations including flexible demand and energy storage systems leverage significant changes in network operation. Thereby, power systems with high renewable penetration manifest deteriorated resilience to disturbances. Hence, the stable operation of the system could be affected. With a paradigm shift, dynamic voltage stability becomes one of the major concerns for the transmission system operators (TSOs). Predicting the dynamic voltage signature for the transmission system with high penetration of renewables is essential to assist in selecting appropriate corrective control. This paper utilized a comprehensive assessment framework to identify the dynamic voltage signature of the power system with PV and various loads. The voltage recovery index has been chosen as the quantifiable index to extricate the dynamic voltage signature. The applicability of the proposed framework is discussed using simulation studies on the IEEE-39 bus test system. © 2020 IEEE.
- Authors: Alzahrani, Saeed , Shah, Rakibuzzaman , Mithulananthan, Nadarajah , Sode-Yome, Arthit
- Date: 2020
- Type: Text , Conference proceedings
- Relation: 2nd International Conference on Smart Power and Internet Energy Systems, SPIES 2020; Bangkok, Thailand; 15th-18th September 2020 p. 275-280
- Full Text:
- Reviewed:
- Description: Renewable power generations including flexible demand and energy storage systems leverage significant changes in network operation. Thereby, power systems with high renewable penetration manifest deteriorated resilience to disturbances. Hence, the stable operation of the system could be affected. With a paradigm shift, dynamic voltage stability becomes one of the major concerns for the transmission system operators (TSOs). Predicting the dynamic voltage signature for the transmission system with high penetration of renewables is essential to assist in selecting appropriate corrective control. This paper utilized a comprehensive assessment framework to identify the dynamic voltage signature of the power system with PV and various loads. The voltage recovery index has been chosen as the quantifiable index to extricate the dynamic voltage signature. The applicability of the proposed framework is discussed using simulation studies on the IEEE-39 bus test system. © 2020 IEEE.
State-of-the-art review of composite marine risers for floating and fixed platforms in deep seas
- Amaechi, Chiemela, Reda, Ahmed, Shahin, Mohamed, Sultan, Ibrahim, Beddu, Salmia, Ja'e, Idris
- Authors: Amaechi, Chiemela , Reda, Ahmed , Shahin, Mohamed , Sultan, Ibrahim , Beddu, Salmia , Ja'e, Idris
- Date: 2023
- Type: Text , Journal article
- Relation: Applied Ocean Research Vol. 138, no. (2023), p.
- Full Text:
- Reviewed:
- Description: The need for the utilisation of marine risers in deep seas has increased in recent years and this is due to increased drilling explorations with the shift in trend from shallower to deep and deeper waters. Also, there have been increased applications in sea-crossing infrastructure resulting in the need for longer risers, leading to a significant weight increase of marine risers used. Composite materials can thus be utilised in marine riser engineering to provide lightweight, fatigue-resistant, corrosion-resistant, low-bending stiffness and high-strength characteristics. In this paper, the history and potential of composite marine risers, including the first successful deployment of a composite riser joint offshore on the Heidrun Platform in 1995, are reviewed. The paper also discusses the advances achieved on composite marine risers for deep waters and presents some recommendations on their use, in light of their current significance and growth. © 2023 The Author(s)
- Authors: Amaechi, Chiemela , Reda, Ahmed , Shahin, Mohamed , Sultan, Ibrahim , Beddu, Salmia , Ja'e, Idris
- Date: 2023
- Type: Text , Journal article
- Relation: Applied Ocean Research Vol. 138, no. (2023), p.
- Full Text:
- Reviewed:
- Description: The need for the utilisation of marine risers in deep seas has increased in recent years and this is due to increased drilling explorations with the shift in trend from shallower to deep and deeper waters. Also, there have been increased applications in sea-crossing infrastructure resulting in the need for longer risers, leading to a significant weight increase of marine risers used. Composite materials can thus be utilised in marine riser engineering to provide lightweight, fatigue-resistant, corrosion-resistant, low-bending stiffness and high-strength characteristics. In this paper, the history and potential of composite marine risers, including the first successful deployment of a composite riser joint offshore on the Heidrun Platform in 1995, are reviewed. The paper also discusses the advances achieved on composite marine risers for deep waters and presents some recommendations on their use, in light of their current significance and growth. © 2023 The Author(s)
Blending big data analytics : review on challenges and a recent study
- Amalina, Fairuz, Targio Hashem, Ibrahim, Azizul, Zati, Fong, Ang, Imran, Muhammad
- Authors: Amalina, Fairuz , Targio Hashem, Ibrahim , Azizul, Zati , Fong, Ang , Imran, Muhammad
- Date: 2020
- Type: Text , Journal article , Review
- Relation: IEEE Access Vol. 8, no. (2020), p. 3629-3645
- Full Text:
- Reviewed:
- Description: With the collection of massive amounts of data every day, big data analytics has emerged as an important trend for many organizations. These collected data can contain important information that may be key to solving wide-ranging problems, such as cyber security, marketing, healthcare, and fraud. To analyze their large volumes of data for business analyses and decisions, large companies, such as Facebook and Google, adopt analytics. Such analyses and decisions impact existing and future technology. In this paper, we explore how big data analytics is utilized as a technique for solving problems of complex and unstructured data using such technologies as Hadoop, Spark, and MapReduce. We also discuss the data challenges introduced by big data according to the literature, including its six V's. Moreover, we investigate case studies of big data analytics on various techniques of such analytics, namely, text, voice, video, and network analytics. We conclude that big data analytics can bring positive changes in many fields, such as education, military, healthcare, politics, business, agriculture, banking, and marketing, in the future. © 2013 IEEE.
- Authors: Amalina, Fairuz , Targio Hashem, Ibrahim , Azizul, Zati , Fong, Ang , Imran, Muhammad
- Date: 2020
- Type: Text , Journal article , Review
- Relation: IEEE Access Vol. 8, no. (2020), p. 3629-3645
- Full Text:
- Reviewed:
- Description: With the collection of massive amounts of data every day, big data analytics has emerged as an important trend for many organizations. These collected data can contain important information that may be key to solving wide-ranging problems, such as cyber security, marketing, healthcare, and fraud. To analyze their large volumes of data for business analyses and decisions, large companies, such as Facebook and Google, adopt analytics. Such analyses and decisions impact existing and future technology. In this paper, we explore how big data analytics is utilized as a technique for solving problems of complex and unstructured data using such technologies as Hadoop, Spark, and MapReduce. We also discuss the data challenges introduced by big data according to the literature, including its six V's. Moreover, we investigate case studies of big data analytics on various techniques of such analytics, namely, text, voice, video, and network analytics. We conclude that big data analytics can bring positive changes in many fields, such as education, military, healthcare, politics, business, agriculture, banking, and marketing, in the future. © 2013 IEEE.
Practitioner perceptions of the feasibility of common frailty screening instruments within general practice settings: a mixed methods study
- Ambagtsheer, Rachel, Casey, Mavourneen, Lawless, Michael, Archibald, Mandy, Yu, Solomon, Kitson, Alison, Beilby, Justin
- Authors: Ambagtsheer, Rachel , Casey, Mavourneen , Lawless, Michael , Archibald, Mandy , Yu, Solomon , Kitson, Alison , Beilby, Justin
- Date: 2022
- Type: Text , Journal article
- Relation: BMC Primary Care Vol. 23, no. 1 (2022), p.
- Full Text:
- Reviewed:
- Description: Background: Frailty is a highly prevalent clinical syndrome increasing older people’s vulnerability to risk of adverse outcomes. Better frailty identification through expanded screening implementation has been advocated within general practice settings, both internationally and within Australia. However, little is known about practitioner perceptions of the feasibility of specific instruments, and the underlying motivations behind those perceptions. Consequently, the purpose of this study was to explore the attitudes and perceptions of a convenience and volunteer sample of Australian general practitioners (GPs) and practice nurses (PNs) towards common frailty screening instruments. Methods: The feasibility of several frailty screening instruments (PRISMA-7 [P7], Edmonton Frail Scale [EFS], FRAIL Questionnaire [FQ], Gait Speed Test [GST], Groningen Frailty Indicator [GFI], Kihon Checklist [KC] and Timed Up and Go [TUG]) to 43 Australian GPs and PNs was assessed. The study adopted a concurrent embedded mixed-methods design incorporating quantitative (ranking exercise) and qualitative (content analysis) data collection integrated during the analysis phase. Results: Practitioners assessed multi-dimensional instruments (EFS, GFI, KC) as having relatively higher clinical utility, better integration into existing assessment processes and stronger links to intervention over uni-dimensional (GST, TUG) and simple (FQ, P7) instruments. Conclusions: While existing frailty screening instruments show promise as an initial step in supporting better care for older people, all the included instruments were associated with perceived advantages and disadvantages. Ultimately, clinicians will need to weigh several factors in their selection of the optimal screening instrument. Further translational research, with a focus on contextual fit, is needed to support clinical decision-making on the selection of instruments for frailty screening. © 2022, The Author(s).
- Authors: Ambagtsheer, Rachel , Casey, Mavourneen , Lawless, Michael , Archibald, Mandy , Yu, Solomon , Kitson, Alison , Beilby, Justin
- Date: 2022
- Type: Text , Journal article
- Relation: BMC Primary Care Vol. 23, no. 1 (2022), p.
- Full Text:
- Reviewed:
- Description: Background: Frailty is a highly prevalent clinical syndrome increasing older people’s vulnerability to risk of adverse outcomes. Better frailty identification through expanded screening implementation has been advocated within general practice settings, both internationally and within Australia. However, little is known about practitioner perceptions of the feasibility of specific instruments, and the underlying motivations behind those perceptions. Consequently, the purpose of this study was to explore the attitudes and perceptions of a convenience and volunteer sample of Australian general practitioners (GPs) and practice nurses (PNs) towards common frailty screening instruments. Methods: The feasibility of several frailty screening instruments (PRISMA-7 [P7], Edmonton Frail Scale [EFS], FRAIL Questionnaire [FQ], Gait Speed Test [GST], Groningen Frailty Indicator [GFI], Kihon Checklist [KC] and Timed Up and Go [TUG]) to 43 Australian GPs and PNs was assessed. The study adopted a concurrent embedded mixed-methods design incorporating quantitative (ranking exercise) and qualitative (content analysis) data collection integrated during the analysis phase. Results: Practitioners assessed multi-dimensional instruments (EFS, GFI, KC) as having relatively higher clinical utility, better integration into existing assessment processes and stronger links to intervention over uni-dimensional (GST, TUG) and simple (FQ, P7) instruments. Conclusions: While existing frailty screening instruments show promise as an initial step in supporting better care for older people, all the included instruments were associated with perceived advantages and disadvantages. Ultimately, clinicians will need to weigh several factors in their selection of the optimal screening instrument. Further translational research, with a focus on contextual fit, is needed to support clinical decision-making on the selection of instruments for frailty screening. © 2022, The Author(s).