{"title":"Smooth Schubert varieties and boolean complexes of involutions","authors":"Vincent Umutabazi","doi":"10.3384/lic.diva-179060","DOIUrl":"https://doi.org/10.3384/lic.diva-179060","url":null,"abstract":"","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116616013","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}
Random matrix theory has found many applications in various fields such as physics, statistics, number theory and so on. One important approach of studying random matrices is based on their spectral properties. In this thesis, we investigate the limiting behaviors of condition numbers of suitable random matrices in terms of large deviations. The thesis is divided into two parts. Part I, provides to the readers an short introduction on the theory of large deviations, some spectral properties of random matrices, and a summary of the results we derived, and in Part II, two papers are appended. In the first paper, we study the limiting behaviors of the 2-norm condition number of pˆ n random matrix in terms of large deviations for large n and p being fixed or p = p(n) Ñ 8 with p(n) = o(n). The entries of the random matrix are assumed to be i.i.d. whose distribution is quite general (namely subGaussian distribution). When the entries are i.i.d. normal random variables, we even obtain an application in statistical inference. The second paper deals with the β-Laguerre (or Wishart) ensembles with a general parameter β ą 0. There are three special cases β = 1, β = 2 and β = 4 which are called, separately, as real, complex and quaternion Wishart matrices. In the paper, large deviations of the condition number are achieved as n Ñ 8, while p is either fixed or p = p(n)Ñ8with p(n) = o(n/ln(n)).
{"title":"Large deviations of condition numbers of random matrices","authors":"Denise Uwamariya","doi":"10.3384/LIC.DIVA-175751","DOIUrl":"https://doi.org/10.3384/LIC.DIVA-175751","url":null,"abstract":"Random matrix theory has found many applications in various fields such as physics, statistics, number theory and so on. One important approach of studying random matrices is based on their spectral properties. In this thesis, we investigate the limiting behaviors of condition numbers of suitable random matrices in terms of large deviations. The thesis is divided into two parts. Part I, provides to the readers an short introduction on the theory of large deviations, some spectral properties of random matrices, and a summary of the results we derived, and in Part II, two papers are appended. In the first paper, we study the limiting behaviors of the 2-norm condition number of pˆ n random matrix in terms of large deviations for large n and p being fixed or p = p(n) Ñ 8 with p(n) = o(n). The entries of the random matrix are assumed to be i.i.d. whose distribution is quite general (namely subGaussian distribution). When the entries are i.i.d. normal random variables, we even obtain an application in statistical inference. The second paper deals with the β-Laguerre (or Wishart) ensembles with a general parameter β ą 0. There are three special cases β = 1, β = 2 and β = 4 which are called, separately, as real, complex and quaternion Wishart matrices. In the paper, large deviations of the condition number are achieved as n Ñ 8, while p is either fixed or p = p(n)Ñ8with p(n) = o(n/ln(n)).","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129450567","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}
To this day, most of the communication networks are characterized by a “monolithic” operating approach. Network elements are configured and operate without any reconfiguration for long time periods. Softwarization, whereby dedicated elements are being replaced by more general-purpose devices, has been lately challenging this existing approach. Virtualizing the infrastructure through the softwarization can provide significant benefits to end users and operators, supporting more flexible service deployment, providing real time monitoring and operational changes. In this licentiate thesis, we consider techniques that can be used towards virtual networking. In Paper I we study a novel allocation technique and traffic optimization process for the access network. Cellular network technologies (i.e. UMTS, LTE, LTE-A) will coexist with non-cellular small cells and offload traffic from cellular to non-cellular networks mainly operating in 3GPP Wi-Fi (IEEE 802.11 standards). This is a scenario for indoor wireless access implementations where offloading mechanisms can improve the QoS offered by the operators, and reduce the traffic handled by the access fronthaul. The analysis of a novel optimization algorithm exhibited a holistic solution for access-core interworking where LWA (LTE-WiFi Aggregation) offers improved performance for the end users. analysed how can affect the power consumption of core network data centers (cooling systems). By applying machine learning techniques using data from a data center, we were able to forecast the power consumption based on to atmospheric weather conditions and analyse its accuracy.
{"title":"Performance Analysis in Wireless HetNets: Traffic, Energy, and Secrecy Considerations","authors":"Georgios Smpokos","doi":"10.3384/LIC.DIVA-174244","DOIUrl":"https://doi.org/10.3384/LIC.DIVA-174244","url":null,"abstract":"To this day, most of the communication networks are characterized by a “monolithic” operating approach. Network elements are configured and operate without any reconfiguration for long time periods. Softwarization, whereby dedicated elements are being replaced by more general-purpose devices, has been lately challenging this existing approach. Virtualizing the infrastructure through the softwarization can provide significant benefits to end users and operators, supporting more flexible service deployment, providing real time monitoring and operational changes. In this licentiate thesis, we consider techniques that can be used towards virtual networking. In Paper I we study a novel allocation technique and traffic optimization process for the access network. Cellular network technologies (i.e. UMTS, LTE, LTE-A) will coexist with non-cellular small cells and offload traffic from cellular to non-cellular networks mainly operating in 3GPP Wi-Fi (IEEE 802.11 standards). This is a scenario for indoor wireless access implementations where offloading mechanisms can improve the QoS offered by the operators, and reduce the traffic handled by the access fronthaul. The analysis of a novel optimization algorithm exhibited a holistic solution for access-core interworking where LWA (LTE-WiFi Aggregation) offers improved performance for the end users. analysed how can affect the power consumption of core network data centers (cooling systems). By applying machine learning techniques using data from a data center, we were able to forecast the power consumption based on to atmospheric weather conditions and analyse its accuracy.","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124296970","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}
In model predictive control (MPC) an optimization problem has to be solved at each time step, which in real-time applications makes it important to solve these efficiently and to have good upper bo ...
{"title":"On Complexity Certification of Active-Set QP Methods with Applications to Linear MPC","authors":"Daniel Arnstrom","doi":"10.3384/LIC.DIVA-173716","DOIUrl":"https://doi.org/10.3384/LIC.DIVA-173716","url":null,"abstract":"In model predictive control (MPC) an optimization problem has to be solved at each time step, which in real-time applications makes it important to solve these efficiently and to have good upper bo ...","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127279494","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}
Existing conventional thermal power plants are retrofitted for flexible operations to assist the transition toward more renewable energies. The deployment of many renewable energy power plants is necessary to achieve a clean environment with less pollution. However, the intermittent nature of renewable energies, due to weather changes, and the lack of efficient large energy storage systems put renewables at a disadvantage. Flexible operations of power plants imply fast and frequent start-ups. Thus, retrofitted power production plants can be utilised as an energy backup to satisfy the immediate demand during peak energy times or when renewable energies are suddenly limited. Large thermal power plants generally employ steam turbines with high inlet temperature and pressure steam conditions. Materials used for components at the high-temperature turbine sections are expected to withstand harsh environments. The use of 9–12 % Cr martensitic steels is desirable due to, among other things, their superior resistance to creep for temperatures up to 625 ◦C. Retrofitting for flexible operations put steam turbine components under high-temperature fatigue loading conditions different from how they were designed before. The flexible operations could lead to fatigue cracking at critical locations, such as grooves and notches at the inner steam turbine casing. Thus, fatigue behaviour understanding of steam turbine materials under such loading conditions is essential for components life prediction. Accurate and less conservative fatigue life prediction approach is necessary to extend the turbine components life, which reduces waste and provides economic benefits. This can be done by extending operations past crack initiation phase and allowing controlled propagation of cracks in the components. Within the 9–12 % Cr steel class, the martensitic steam turbine steel called FB2 is studied under high-temperature fatigue. This includes investigating hightemperature fatigue life behaviour, cyclic deformation behaviour, stress relaxation behaviour, and crack propagation behaviour along with crack closure behaviour. This was achieved by experimentally testing samples made from FB2 steel under isothermal low cycle fatigue, isothermal fatigue crack propagation, and thermomechanical fatigue crack propagation.
{"title":"High-Temperature Fatigue in a Steam Turbine Steel : Modelling of Cyclic Deformation and Crack Closure","authors":"A. Azeez","doi":"10.3384/LIC.DIVA-173354","DOIUrl":"https://doi.org/10.3384/LIC.DIVA-173354","url":null,"abstract":"Existing conventional thermal power plants are retrofitted for flexible operations to assist the transition toward more renewable energies. The deployment of many renewable energy power plants is necessary to achieve a clean environment with less pollution. However, the intermittent nature of renewable energies, due to weather changes, and the lack of efficient large energy storage systems put renewables at a disadvantage. Flexible operations of power plants imply fast and frequent start-ups. Thus, retrofitted power production plants can be utilised as an energy backup to satisfy the immediate demand during peak energy times or when renewable energies are suddenly limited. Large thermal power plants generally employ steam turbines with high inlet temperature and pressure steam conditions. Materials used for components at the high-temperature turbine sections are expected to withstand harsh environments. The use of 9–12 % Cr martensitic steels is desirable due to, among other things, their superior resistance to creep for temperatures up to 625 ◦C. Retrofitting for flexible operations put steam turbine components under high-temperature fatigue loading conditions different from how they were designed before. The flexible operations could lead to fatigue cracking at critical locations, such as grooves and notches at the inner steam turbine casing. Thus, fatigue behaviour understanding of steam turbine materials under such loading conditions is essential for components life prediction. Accurate and less conservative fatigue life prediction approach is necessary to extend the turbine components life, which reduces waste and provides economic benefits. This can be done by extending operations past crack initiation phase and allowing controlled propagation of cracks in the components. Within the 9–12 % Cr steel class, the martensitic steam turbine steel called FB2 is studied under high-temperature fatigue. This includes investigating hightemperature fatigue life behaviour, cyclic deformation behaviour, stress relaxation behaviour, and crack propagation behaviour along with crack closure behaviour. This was achieved by experimentally testing samples made from FB2 steel under isothermal low cycle fatigue, isothermal fatigue crack propagation, and thermomechanical fatigue crack propagation.","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115426802","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}
{"title":"Decision Models for the Procurement of Subsidised Air Services","authors":"Alan Kinene","doi":"10.3384/LIC.DIVA-173222","DOIUrl":"https://doi.org/10.3384/LIC.DIVA-173222","url":null,"abstract":"","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130682521","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}
The two topics at the heart of this thesis are how to improve control of industrial manipulators and how to reason about the role of models in automatic control. On industrial manipulators, two case studies are presented. The first investigates estimation with inertial sensors, and the second compares control by feedback linearization to control based on gain-scheduling. The contributions on the second topic illustrate the close connection between control and estimation in different ways. A conceptual model of control is introduced, which can be used to emphasize the role of models as well as the human aspect of control engineering. Some observations are made regarding blockdiagram reformulations that illustrate the relation between models, control and inversion. Finally, a suggestion for how the internal model principle, internal model control, disturbance observers and Youla-Kučera parametrization can be introduced in a unified way is presented.
本文的两个核心主题是如何改进工业机械臂的控制和如何推理模型在自动控制中的作用。在工业机械臂方面，给出了两个案例研究。第一部分研究了惯性传感器的估计，第二部分比较了反馈线性化控制与基于增益调度的控制。对第二个主题的贡献以不同的方式说明了控制和评估之间的密切联系。介绍了一个控制的概念模型，它可以用来强调模型的作用以及控制工程中的人的方面。对框图的重新表述进行了一些观察，说明了模型、控制和反演之间的关系。最后，对如何统一引入内模原理、内模控制、扰动观测器和youla - ku era参数化提出了建议。
{"title":"Control, Models and Industrial Manipulators","authors":"E. Hedberg","doi":"10.3384/lic.diva-171560","DOIUrl":"https://doi.org/10.3384/lic.diva-171560","url":null,"abstract":"The two topics at the heart of this thesis are how to improve control of industrial manipulators and how to reason about the role of models in automatic control. On industrial manipulators, two case studies are presented. The first investigates estimation with inertial sensors, and the second compares control by feedback linearization to control based on gain-scheduling. The contributions on the second topic illustrate the close connection between control and estimation in different ways. A conceptual model of control is introduced, which can be used to emphasize the role of models as well as the human aspect of control engineering. Some observations are made regarding blockdiagram reformulations that illustrate the relation between models, control and inversion. Finally, a suggestion for how the internal model principle, internal model control, disturbance observers and Youla-Kučera parametrization can be introduced in a unified way is presented.","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124278177","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 : 2020-11-24DOI: 10.3384/diss.diva-171558
Juan Felipe Ruiz Muñoz
{"title":"The Problem of Formulating Design Problems : A Typology of Design Briefs","authors":"Juan Felipe Ruiz Muñoz","doi":"10.3384/diss.diva-171558","DOIUrl":"https://doi.org/10.3384/diss.diva-171558","url":null,"abstract":"","PeriodicalId":303036,"journal":{"name":"Linköping Studies in Science and Technology. Licentiate Thesis","volume":"103 3-4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114009148","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：