Grain boundaries play an important role in dictating the mechanical and physical properties of nanocrystalline (NC) materials because of the increased volume fraction of inter crystalline components as the grain size decreases. In general, grain boundaries have a high energy level and there exists a thermodynamic driving force to reduce the overall area of grain boundaries through grain coarsening, making NC material systems intrinsically unstable. Recent investigations also indicate that mechanical deformation can promote grain growth in NC material even at the cryogenic temperatures. In this chapter, first, the current investigation on the grain boundary structures of NC metallic materials is briefly reviewed and then the state-of-the-art of experimental results on the microstructural stability during deformation processes is discussed. Finally, several key issues for improving the microstructure stability of NC metallic materials and possible future work are discussed.
{"title":"Grain Boundary Effects on Microstructural Stability of Nanocrystalline Metallic Materials","authors":"Xiao-fei Zhu, Guang-Ping Zhang, Cheng Yan","doi":"10.5772/66426","DOIUrl":"https://doi.org/10.5772/66426","url":null,"abstract":"Grain boundaries play an important role in dictating the mechanical and physical properties of nanocrystalline (NC) materials because of the increased volume fraction of inter crystalline components as the grain size decreases. In general, grain boundaries have a high energy level and there exists a thermodynamic driving force to reduce the overall area of grain boundaries through grain coarsening, making NC material systems intrinsically unstable. Recent investigations also indicate that mechanical deformation can promote grain growth in NC material even at the cryogenic temperatures. In this chapter, first, the current investigation on the grain boundary structures of NC metallic materials is briefly reviewed and then the state-of-the-art of experimental results on the microstructural \u0000stability during deformation processes is discussed. Finally, several key issues for improving the microstructure stability of NC metallic materials and possible future work are discussed.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77303533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-03DOI: 10.1108/IJILT-07-2016-0022
Nick Kelly, M. Montenegro, C. Gonzalez, Paula Clasing, Augusto Sandoval, Magdalena Jara, Elvira Saurina, R. Alarcón
Purpose - The paper demonstrates the utility of combining event-centred and variable-centred approaches when analysing big data for higher education institutions. It uses a large, university-wide dataset to demonstrate the methodology for this analysis by case study. It presents empirical findings about relationships between student behaviours in a learning management system and the learning outcomes of students, and further explores these findings using process modelling techniques. Design/methodology/approach - The paper describes a two-year study in a Chilean university, using big data from a learning management system and from the central university database of student results and demographics. Descriptive statistics of LMS use in different years presents an overall picture of student use of the system. Process mining is described as an event-centred approach to give a deeper level of understanding of these findings. Findings - The study found evidence to support the idea that instructors do not strongly influence student use of an LMS. It replicates existing studies to show that higher performing students use an LMS differently to lower performing students. Research limitations/implications - The study is limited by its institutional context, its two-year time frame, and its exploratory mode of investigation to create a case study. Practical implications - The paper is useful for institutions in developing methodology for using big data from a learning management system to make use of event-centred approaches. Originality/value - The paper is valuable in replicating and extending recent studies using event-centred approaches to analysis of learning data. The study here is a larger scale than existing studies (using a university-wide dataset), in a novel context (Latin America), that provides a clear description for how and why the methodology should inform institutional approaches.
{"title":"Combining event- and variable-centred approaches to institution-facing learning analytics at the unit of study level","authors":"Nick Kelly, M. Montenegro, C. Gonzalez, Paula Clasing, Augusto Sandoval, Magdalena Jara, Elvira Saurina, R. Alarcón","doi":"10.1108/IJILT-07-2016-0022","DOIUrl":"https://doi.org/10.1108/IJILT-07-2016-0022","url":null,"abstract":"Purpose - The paper demonstrates the utility of combining event-centred and variable-centred approaches when analysing big data for higher education institutions. It uses a large, university-wide dataset to demonstrate the methodology for this analysis by case study. It presents empirical findings about relationships between student behaviours in a learning management system and the learning outcomes of students, and further explores these findings using process modelling techniques. \u0000 \u0000 Design/methodology/approach - The paper describes a two-year study in a Chilean university, using big data from a learning management system and from the central university database of student results and demographics. Descriptive statistics of LMS use in different years presents an overall picture of student use of the system. Process mining is described as an event-centred approach to give a deeper level of understanding of these findings. \u0000 \u0000 Findings - The study found evidence to support the idea that instructors do not strongly influence student use of an LMS. It replicates existing studies to show that higher performing students use an LMS differently to lower performing students. \u0000 \u0000 Research limitations/implications - The study is limited by its institutional context, its two-year time frame, and its exploratory mode of investigation to create a case study. \u0000 \u0000 Practical implications - The paper is useful for institutions in developing methodology for using big data from a learning management system to make use of event-centred approaches. \u0000 \u0000 Originality/value - The paper is valuable in replicating and extending recent studies using event-centred approaches to analysis of learning data. The study here is a larger scale than existing studies (using a university-wide dataset), in a novel context (Latin America), that provides a clear description for how and why the methodology should inform institutional approaches.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85004966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.5204/thesis.eprints.105357
L. Xiao
This thesis provides potential new therapeutic approaches for the prevention and treatment of destructive bone diseases. It investigates the cellular and molecular mechanisms of abnormal bone remodelling under inflammation, therefore sheds light on the pathogenesis of inflammation induced bone loss.
{"title":"Dissecting the role of sphingosine 1-phosphate-sphingosine 1-phosphate receptor 1 in inflammatory bone remodelling","authors":"L. Xiao","doi":"10.5204/thesis.eprints.105357","DOIUrl":"https://doi.org/10.5204/thesis.eprints.105357","url":null,"abstract":"This thesis provides potential new therapeutic approaches for the prevention and treatment of destructive bone diseases. It investigates the cellular and molecular mechanisms of abnormal bone remodelling under inflammation, therefore sheds light on the pathogenesis of inflammation induced bone loss.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"111 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77878631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.5204/thesis.eprints.103846
Fernando Vanegas Alvarez
This research is a novel approach to enabling Unmanned Aerial Vehicle (UAV) navigation and target finding and tracking missions under uncertainty in cluttered and GPS-denied environments. A novel framework, implemented as a modular system, formulates the missions as online Partially Observable Markov Decision Processes (POMDP). The online POMDP computes a motion policy that balances multiple mission objectives optimally. The motion policy is updated while flying based onboard sensor observations. This research provides an enabling technology for UAV missions such as search and rescue, biodiversity assessment, underground mining and infrastructure inspection in challenging and natural environments.
{"title":"Uncertainty based online planning for UAV missions in GPS-denied and cluttered environments","authors":"Fernando Vanegas Alvarez","doi":"10.5204/thesis.eprints.103846","DOIUrl":"https://doi.org/10.5204/thesis.eprints.103846","url":null,"abstract":"This research is a novel approach to enabling Unmanned Aerial Vehicle (UAV) navigation and target finding and tracking missions under uncertainty in cluttered and GPS-denied environments. A novel framework, implemented as a modular system, formulates the missions as online Partially Observable Markov Decision Processes (POMDP). The online POMDP computes a motion policy that balances multiple mission objectives optimally. The motion policy is updated while flying based onboard sensor observations. This research provides an enabling technology for UAV missions such as search and rescue, biodiversity assessment, underground mining and infrastructure inspection in challenging and natural environments.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"112 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80873603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.5204/thesis.eprints.105133
Colin M. Davis
This thesis employs imaging analysis using CT and MRI scans to comprehensively document the changing three-dimensional pedicle anatomy that occurs in the growing spine of adolescent idiopathic scoliosis patients and compare this to healthy control subjects. This study aims to not only provide information regarding the pathophysiology of adolescent idiopathic scoliosis but also to provide critical information to spinal surgeons operating on these spines to reduce the risk of serious complications.
{"title":"Imaging analysis of morphological changes to vertebrae in adolescent idiopathic scoliosis","authors":"Colin M. Davis","doi":"10.5204/thesis.eprints.105133","DOIUrl":"https://doi.org/10.5204/thesis.eprints.105133","url":null,"abstract":"This thesis employs imaging analysis using CT and MRI scans to comprehensively document the changing three-dimensional pedicle anatomy that occurs in the growing spine of adolescent idiopathic scoliosis patients and compare this to healthy control subjects. This study aims to not only provide information regarding the pathophysiology of adolescent idiopathic scoliosis but also to provide critical information to spinal surgeons operating on these spines to reduce the risk of serious complications.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84873278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.5204/thesis.eprints.107850
M. J. Uddin
This thesis involves analysis of artificial materials to investigate metamaterial behavior and characteristics. Extraction techniques are used to validate the electromagnetic properties and different microwave applications are investigated. A new geometric structure is designed using dual star split ring resonator, which introduces a sharp, wide rejection band. A metamaterial microwave absorber suitable for dual-band operation and insensitive to incident polarization was also developed.
{"title":"Synthesis and analysis of metamaterial structure for microwave frequency applications","authors":"M. J. Uddin","doi":"10.5204/thesis.eprints.107850","DOIUrl":"https://doi.org/10.5204/thesis.eprints.107850","url":null,"abstract":"This thesis involves analysis of artificial materials to investigate metamaterial behavior and characteristics. Extraction techniques are used to validate the electromagnetic properties and different microwave applications are investigated. A new geometric structure is designed using dual star split ring resonator, which introduces a sharp, wide rejection band. A metamaterial microwave absorber suitable for dual-band operation and insensitive to incident polarization was also developed.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89981334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.5204/thesis.eprints.103083
Zutao Wu
This thesis presents a study of alignment-free methods for genetic sequence comparison. By using representations based on k-mers – short subsequences of length k - sequence similarity can be measured rapidly and accurately by calculating the distance between these paired representations. This research utilises and adapts conventional methods from information retrieval to generate novel representations for k-mers and sequence fragments. Precision was further improved through the use of machine learning approaches - especially neural networks - to learn relationships between k-mers and to generate enhanced sequence representations. These approaches have applications in large scale sequence comparison, especially in the analysis of metagenomic samples.
{"title":"Kmer-based sequence representations for fast retrieval and comparison","authors":"Zutao Wu","doi":"10.5204/thesis.eprints.103083","DOIUrl":"https://doi.org/10.5204/thesis.eprints.103083","url":null,"abstract":"This thesis presents a study of alignment-free methods for genetic sequence comparison. By using representations based on k-mers – short subsequences of length k - sequence similarity can be measured rapidly and accurately by calculating the distance between these paired representations. This research utilises and adapts conventional methods from information retrieval to generate novel representations for k-mers and sequence fragments. Precision was further improved through the use of machine learning approaches - especially neural networks - to learn relationships between k-mers and to generate enhanced sequence representations. These approaches have applications in large scale sequence comparison, especially in the analysis of metagenomic samples.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84726660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developing major infrastructure and construction (MIC) projects is complicated, since it involves multifaceted policy issues. As a result, appropriate participatory mechanisms have been increasingly employed to improve the legitimacy of the project decision process. Yet it cannot always guarantee a mutually acceptable solution since the expectations and requirements of multiple stakeholders involved can be diverse and even conflicting. Overcoming this necessitates a thorough identification and careful analysis of the expectations of various stakeholder groups in MIC projects. On the other hand, though most project stakeholder concerns are consistent across the globe, contextual differences may lead to diverse priority levels being attached to these factors. This research, therefore, aimed to examine the perceptual differences between paired stakeholder groups from mainland China mega-cities and Hong Kong in rating their concerns over MIC projects. The research findings are expected to benefit both the Central Government of China and the Government of Hong Kong SAR for coping better with the rapid expansion of MIC projects in the territory and the increasing expectations of social equality, and therefore achieving the much desired harmonious development of the community.
{"title":"Investigating stakeholder concerns during public participation","authors":"T. Li, S. T. Ng, M. Skitmore, Nan Li","doi":"10.1680/JMUEN.15.00018","DOIUrl":"https://doi.org/10.1680/JMUEN.15.00018","url":null,"abstract":"Developing major infrastructure and construction (MIC) projects is complicated, since it involves multifaceted policy issues. As a result, appropriate participatory mechanisms have been increasingly employed to improve the legitimacy of the project decision process. Yet it cannot always guarantee a mutually acceptable solution since the expectations and requirements of multiple stakeholders involved can be diverse and even conflicting. Overcoming this necessitates a thorough identification and careful analysis of the expectations of various stakeholder groups in MIC projects. On the other hand, though most project stakeholder concerns are consistent across the globe, contextual differences may lead to diverse priority levels being attached to these factors. This research, therefore, aimed to examine the perceptual differences between paired stakeholder groups from mainland China mega-cities and Hong Kong in rating their concerns over MIC projects. The research findings are expected to benefit both the Central Government of China and the Government of Hong Kong SAR for coping better with the rapid expansion of MIC projects in the territory and the increasing expectations of social equality, and therefore achieving the much desired harmonious development of the community.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90662457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-11-07DOI: 10.1142/S0219519416500937
Lingling Wei, Qiang Chen, Zhiyong Li
Different stent structures lead to different deformations of blood vessels, such as different cross-section shapes, which further influence the blood flow patterns. In this paper, sis non-commercial stents with different link structures called I-, C-, S-, U-, N-, and W-types were considered. Their influences on arteries with five different curvatures (i.e., 0 ∘,15 ∘ , 30 ∘, 45 ∘, and 60∘) were studied using finite element method. Four indices including the maximum plastic strain of stents, the rate of expansion, the maximum von Mises stress and the ellipticity of arteries, were compared for all cases. The results showed that the S-type or U-type stents, with larger plastic strain and lower von Mises stress on the arteries, provided the optimal outcome. As the link structures became complex, the arterial expansion increased monotonically, while the ellipticity of arteries showed a decreasing tendency in the vessel models. The present study could be useful for the commercial design and clinic selection of a stent with different link structures for different curved arteries.
{"title":"Study on the impact of straight stents on arteries with different curvatures","authors":"Lingling Wei, Qiang Chen, Zhiyong Li","doi":"10.1142/S0219519416500937","DOIUrl":"https://doi.org/10.1142/S0219519416500937","url":null,"abstract":"Different stent structures lead to different deformations of blood vessels, such as different cross-section shapes, which further influence the blood flow patterns. In this paper, sis non-commercial stents with different link structures called I-, C-, S-, U-, N-, and W-types were considered. Their influences on arteries with five different curvatures (i.e., 0 ∘,15 ∘ , 30 ∘, 45 ∘, and 60∘) were studied using finite element method. Four indices including the maximum plastic strain of stents, the rate of expansion, the maximum von Mises stress and the ellipticity of arteries, were compared for all cases. The results showed that the S-type or U-type stents, with larger plastic strain and lower von Mises stress on the arteries, provided the optimal outcome. As the link structures became complex, the arterial expansion increased monotonically, while the ellipticity of arteries showed a decreasing tendency in the vessel models. The present study could be useful for the commercial design and clinic selection of a stent with different link structures for different curved arteries.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90848919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Porous graphene materials possess a unique structure with interconnected networks,high surface area, and high pore volume. Because of the combination of its remarkable architecture and intrinsic properties, such as high mechanical strength, excellent electrical conductivity, and good thermal stability, porous graphene has attracted tremendous attention in many fields, such as nanocomposites, lithium batteries, supercapacitors, and dye-sensitized solar cells. This chapter reviews synthesis methods, properties, and several key applications of porous graphene materials.
{"title":"Porous Graphene Materials for Energy Storage and Conversion Applications","authors":"K. C. Wasalathilake, G. Ayoko, Cheng Yan","doi":"10.5772/63554","DOIUrl":"https://doi.org/10.5772/63554","url":null,"abstract":"Porous graphene materials possess a unique structure with interconnected networks,high surface area, and high pore volume. Because of the combination of its remarkable architecture and intrinsic properties, such as high mechanical strength, excellent electrical conductivity, and good thermal stability, porous graphene has attracted \u0000tremendous attention in many fields, such as nanocomposites, lithium batteries, supercapacitors, and dye-sensitized solar cells. This chapter reviews synthesis methods, properties, and several key applications of porous graphene materials.","PeriodicalId":21486,"journal":{"name":"Science & Engineering Faculty","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74105025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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