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Iglesias, Jennifer. "Approximation Algorithms for Faster Communication and Cheaper Networks Using Linear Programming." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1050.
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As we are currently in the information age, people expect access to information to exist by default. In order to facilitate the communication of knowledge, efficient networks must be built. In particular, the networks must be built satisfying some constraints while minimizing cost or time. These constraints often make these problems NP-hard. In this thesis, we investigate two different sets of problems: communicating information quickly and building cheap networks. In the communication problems, the goal is to minimize the number of rounds of communication. In the network design problems the goal is to construct a network of minimum cost.
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Martin, P. M. "Advanced linear modem design for narrowband mobile communications." Thesis, University of Bristol, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303851.
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Abid, Muhammad Rizwan. "Visual Recognition of a Dynamic Arm Gesture Language for Human-Robot and Inter-Robot Communication." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32800.
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This thesis presents a novel Dynamic Gesture Language Recognition (DGLR) system for human-robot and inter-robot communication.
We developed and implemented an experimental setup consisting of a humanoid robot/android able to recognize and execute in real time all the arm gestures of the Dynamic Gesture Language (DGL) in similar way as humans do.
Our DGLR system comprises two main subsystems: an image processing (IP) module and a linguistic recognition system (LRS) module. The IP module enables recognizing individual DGL gestures. In this module, we use the bag-of-features (BOFs) and a local part model approach for dynamic gesture recognition from images. Dynamic gesture classification is conducted using the BOFs and nonlinear support-vector-machine (SVM) methods. The multiscale local part model preserves the temporal context.
The IP module was tested using two databases, one consisting of images of a human performing a series of dynamic arm gestures under different environmental conditions and a second database consisting of images of an android performing the same series of arm gestures.
The linguistic recognition system (LRS) module uses a novel formal grammar approach to accept DGL-wise valid sequences of dynamic gestures and reject invalid ones. LRS consists of two subsystems: one using a Linear Formal Grammar (LFG) to derive the valid sequence of dynamic gestures and another using a Stochastic Linear Formal Grammar (SLFG) to occasionally recover gestures that were unrecognized by the IP module. Experimental results have shown that the DGLR system had a slightly better overall performance when recognizing gestures made by a human subject (98.92% recognition rate) than those made by the android (97.42% recognition rate).
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Jeon, Ham Hee. "Highly efficient linear CMOS power amplifiers for wireless communications." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47528.
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The rapidly expanding wireless market requires low cost, high integration and high performance of wireless communication systems. CMOS technology provides benefits of cost effectiveness and higher levels of integration. However, the design of highly efficient linear CMOS power amplifier that meets the requirement of advanced communication standards is a challenging task because of the inherent difficulties in CMOS technology. The objective of this research is to realize PAs for wireless communication systems that overcoming the drawbacks of CMOS process, and to develop design approaches that satisfying the demands of the industry. In this dissertation, a cascode bias technique is proposed for improving linearity and reliability of the multi-stage cascode CMOS PA. In addition, to achieve load variation immunity characteristic and to enhance matching and stability, a fully-integrated balanced PA is implemented in a 0.18-m CMOS process. A triple-mode balanced PA using switched quadrature coupler is also proposed, and this work saved a large amount of quiescent current and further improved the efficiency in the back-off power. For the low losses and a high quality factor of passive output combining, a transformer-based quadrature coupler was implemented using integrated passive device (IPD) process. Various practical approaches for linear CMOS PA are suggested with the verified results, and they demonstrate the potential PA design approach for WCDMA applications using a standard CMOS technology.
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Shaw, Stephanie M. "Frequency Response of Synthetic Vocal Fold Models with Linear and Nonlinear Material Properties." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2433.
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Previous studies have shown the importance of cricothyroid muscle activation in altering fundamental frequency in the human voice. Other studies have investigated the non-linear properties of vocal fold tissue and the impact of this non-linearity on frequency response. Several physical models of the vocal folds have been made for research purposes. However, all have been isotropic in nature with linear stress-strain properties. The purpose of this study was to create a physical model with non-linear stress-strain properties to investigate the frequency response of the model as cricothyroid muscle activation was simulated (in other words, as the vocal folds were stretched in an anterior-posterior dimension). In this study the physical models of the vocal folds were stretched in 1 mm increments and the fundamental frequency (F0) was recorded at each position. Subglottal pressure was also monitored and phonation threshold pressures were recorded for each adjustment in length and vocal fold tension, because this can influence F0. Results were obtained for models with and without non-linear properties for comparison. Tensile tests were also conducted for the linear and non-linear synthetic vocal folds. Results indicate that non-linear models demonstrated a more substantial frequency response than linear vocal fold models and a more predictable F0 increase with respect to increasing vocal fold length. Phonation threshold pressures also increased with increasing vocal fold length for non-linear vocal fold models. This trend was reversed for linear vocal fold models, with phonation threshold pressures decreasing with increasing vocal fold length. These results indicate that the non-linear vocal fold models more accurately represent the human vocal folds than do linear models. This study serves as the foundation for future research to quantify the impact of non-linear tissue properties versus active tensioning (through antagonistic thyroarytenoid muscle activation) on F0 response and phonation threshold pressure.
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Srirattana, Nuttapong. "High-Efficiency Linear RF Power Amplifiers Development." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6899.
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Next generation mobile communication systems require the use of linear RF power amplifier for higher data transmission rates. However, linear RF power amplifiers are inherently inefficient and usually require additional circuits or further system adjustments for better efficiency. This dissertation focuses on the development of new efficiency enhancement schemes for linear RF power amplifiers.
The multistage Doherty amplifier technique is proposed to improve the performance of linear RF power amplifiers operated in a low power level. This technique advances the original Doherty amplifier scheme by improving the efficiency at much lower power level. The proposed technique is supported by a new approach in device periphery calculation to reduce AM/AM distortion and a further improvement of linearity by the bias adaptation concept.
The device periphery adjustment technique for efficiency enhancement of power amplifier integrated circuits is also proposed in this work. The concept is clearly explained together with its implementation on CMOS and SiGe RF power amplifier designs. Furthermore, linearity improvement technique using the cancellation of nonlinear terms is proposed for the CMOS power amplifier in combination with the efficiency enhancement technique.
In addition to the efficiency enhancement of power amplifiers, a scalable large-signal MOSFET model using the modified BSIM3v3 approach is proposed. A new scalable substrate network model is developed to enhance the accuracy of the BSIM3v3 model in RF and microwave applications. The proposed model simplifies the modeling of substrate coupling effects in MOS transistor and provides great accuracy in both small-signal and large-signal performances.
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Udayashankara, V. "DSP Techniques for Performance Enhancement of Digital Hearing Aid." Thesis, Indian Institute of Science, 1995. http://hdl.handle.net/2005/156.
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Hearing impairment is the number one chronic disability affecting people in the world. Many people have great difficulty in understanding speech with background noise. This is especially true for a large number of elderly people and the sensorineural impaired persons. Several investigations on speech intelligibility have demonstrated that subjects with sensorineural loss may need a 5-15 dB higher signal-to-noise ratio than the normal hearing subjects. While most defects in transmission chain up to cochlea can nowadays be successfully rehabilitated by means of surgery, the great majority of the remaining inoperable cases are sensorineural hearing impaired, Recent statistics of the hearing impaired patients applying for a hearing aid reveal that 20% of the cases are due to conductive losses, more than 50% are due to sensorineural losses, and the rest 30% of the cases are of mixed origin. Presenting speech to the hearing impaired in an intelligible form remains a major challenge in hearing-aid research today. Even-though various methods have been suggested in the literature for the minimization of noise from the contaminated speech signals, they fail to give good SNR improvement and intelligibility improvement for moderate to-severe sensorineural loss subjects. So far, the power and capability of Newton's method, Nonlinear adaptive filtering methods and the feedback type artificial neural networks have not been exploited for this purpose. Hence we resort to the application of all these methods for improving SNR and intelligibility for the sensorineural loss subjects. Digital hearing aids frequently employ the concept of filter banks. One of the major drawbacks of this techniques is the complexity of computation requiring more number of multiplications. This increases the power consumption. Therefore this Thesis presents the new approach to speech enhancement for the hearing impaired and also the construction of filter bank in Digital hearing aid with minimum number of multiplications. The following are covered in this thesis.
One of the most important application of adaptive systems is in noise cancellation using adaptive filters. The ANC setup requires two input signals (viz., primary and reference). The primary input consists of the sum of the desired signal and noise which is uncorrelated. The reference input consists of mother noise which is correlated in Some unknown way with noise of primary input. The primary signal is obtained by placing the omnidirectional microphone just above one ear on the head of the KEMAR mannikan and the reference signal is obtained by placing the hypercardioid microphone at the center of the vertebral column on the back. Conventional speech enhancement techniques use linear schemes for enhancing speech signals. So far Nonlinear adaptive filtering techniques are not used in hearing aid applications. The motivation behind the use of nonlinear model is that it gives better noise suppression as compared to linear model. This is because the medium through which signals reach the microphone may be highly nonlinear. Hence the use of linear schemes, though motivated by computational simplicity and mathematical tractability, may be suboptimal. Hence, we propose the use of nonlinear models to enhance the speech signals for the hearing impaired: We propose both Linear LMS and Nonlinear second order Volterra LMS schemes to enhance speech signals. Studies conducted for different environmental noise including babble, cafeteria and low frequency noise show that the second-order Volterra LMS performs better compared to linear LMS algorithm. We use measures such as signal-to-noise ratio (SNR),
time plots, and intelligibility tests for performance comparison.
We also propose an ANC scheme which uses Newton's method to enhance speech signals. The main problem associated with LMS based ANC is that their convergence is slow and hence their performance becomes poor for hearing aid applications. The reason for choosing Newton's method is that they have high performance adaptive-filtering methods that often converge and track faster than LMS method. We propose two models to enhance speech signals: one is conventional linear model and the other is a nonlinear model using a second order Volterra function. Development of Newton's type algorithm for linear mdel results in familiar Recursive least square (RLS) algorithm. The performance of both linear and non-linear Newton's algorithm is evaluated for babble, cafeteria and frequency noise. SNR, timeplots and intelligibility tests are used for performance comparison. The results show that Newton's method using Volterra nonlinearity performs better than RLS method.
ln addition to the ANC based schemes, we also develop speech enhancement for the hearing impaired by using the feedback type neural network (FBNN). The main reason is that here we have parallel algorithm which can be implemented directly in hardware. We translate the speech enhancement problem into a neural network (NN) framework by forming an appropriate energy function. We propose both linear and nonlinear FBNN for enhancing the speech signals. Simulated studies on different environmental noise reveal that the FBNN using the Volterra nonlinearity is superior to linear FBNN in enhancing speech signals. We use SNR, time plots, and intelligibility tests for performance comparison.
The design of an effective hearing aid is a challenging problem for sensorineural hearing impaired people. For persons with sensorineural losses it is necessary that the frequency response should be optimally fitted into their residual auditory area. Digital filter enhances the performance of the hearing aids which are either difficult or impossible to realize using analog techniques. The major problem in digital hearing aid is that of reducing power consumption. Multiplication is one of the most power consuming operation in digital filtering. Hence a serious effort has been made to design filter bank with minimum number of multiplications, there by minimizing the power consumption. It is achieved by using Interpolated and complementary FIR filters. This method gives significant savings in the number of arithmetic operations.
The Thesis is concluded by summarizing the results of analysis, and suggesting scope for further investigation
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Kim, Byoung Joon. "The Impact of the Internet on Civic and Political Participation in Local Governance: A Mulitilevel Model for Bridging Individual and Group Levels of Analysis." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26129.
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Politically interested individual citizens often use information and communication technology (ICT) to facilitate and augment their civic and political participation. At the local level, ICT plays an important role for communication and information sharing in order for local groups to create awareness and draw citizens into public deliberation about local issues and concerns. This research examines the interplay of individual and local group level factors in order to better understand the relationship between civic engagement and ICT, especially the internet, by using household survey data from the town of Blacksburg, Virginia and environs in 2005 and 2006. It seeks to reconcile those different levels of analysis relating to the use and impact of the internet on civic engagement in local governance.
This study identifies the distinctive influences at both the individual citizen level and the group level by applying a multilevel statistical model (the Hierarchical Linear Model). First, this study found the effects of internal and external political efficacy and community collective efficacy as significant individual level influences on internet use for civic and political purposes. Second, group internet useâ which includes new internet technologiesâ and group political discussion were revealed as key influences on citizensâ perspectives on the helpfulness of the internet for civic and political purposes at the group level of analysis. Finally, in multilevel analysis, those recognized group level variables (group internet use and group political discussion and interests) led to positive agreement with the following statements: 1) the internet has helped me feel more connected with people like myself in the local area; 2) the internet has helped me feel more connected with a diversity of people in the local area; and 3) the internet has helped me become more involved in local issues that interest me when taking individual level variables into account.Ph. D.
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He, Qing. "Robust-Intelligent Traffic Signal Control within a Vehicle-to-Infrastructure and Vehicle-to-Vehicle Communication Environment." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/196011.
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Modern traffic signal control systems have not changed significantly in the past 40-50 years. The most widely applied traffic signal control systems are still time-of-day, coordinated-actuated system, since many existing advanced adaptive signal control systems are too complicated and fathomless for most of people. Recent advances in communications standards and technologies provide the basis for significant improvements in traffic signal control capabilities. In the United States, the IntelliDriveSM program (originally called Vehicle Infrastructure Integration - VII) has identified 5.9GHz Digital Short Range Communications (DSRC) as the primary communications mode for vehicle-to-vehicle (v2v) and vehicle-to-infrastructure (v2i) safety based applications, denoted as v2x. The ability for vehicles and the infrastructure to communication information is a significant advance over the current system capability of point presence and passage detection that is used in traffic control systems. Given enriched data from IntelliDriveSM, the problem of traffic control can be solved in an innovative data-driven and mathematical way to produce robust and optimal outputs.In this doctoral research, three different problems within a v2x environment- "enhanced pseudo-lane-level vehicle positioning", "robust coordinated-actuated multiple priority control", and "multimodal platoon-based arterial traffic signal control", are addressed with statistical techniques and mathematical programming.First, a pseudo-lane-level GPS positioning system is proposed based on an IntelliDriveSM v2x environment. GPS errors can be categorized into common-mode errors and noncommon-mode errors, where common-mode errors can be mitigated by differential GPS (DGPS) but noncommon-mode cannot. Common-mode GPS errors are cancelled using differential corrections broadcast from the road-side equipment (RSE). With v2i communication, a high fidelity roadway layout map (called MAP in the SAE J2735 standard) and satellite pseudo-range corrections are broadcast by the RSE. To enhance and correct lane level positioning of a vehicle, a statistical process control approach is used to detect significant vehicle driving events such as turning at an intersection or lane-changing. Whenever a turn event is detected, a mathematical program is solved to estimate and update the GPS noncommon-mode errors. Overall the GPS errors are reduced by corrections to both common-mode and noncommon-mode errors.Second, an analytical mathematical model, a mixed-integer linear program (MILP), is developed to provide robust real-time multiple priority control, assuming penetration of IntelliDriveSM is limited to emergency vehicles and transit vehicles. This is believed to be the first mathematical formulation which accommodates advanced features of modern traffic controllers, such as green extension and vehicle actuations, to provide flexibility in implementation of optimal signal plans. Signal coordination between adjacent signals is addressed by virtual coordination requests which behave significantly different than the current coordination control in a coordinated-actuated controller. The proposed new coordination method can handle both priority and coordination together to reduce and balance delays for buses and automobiles with real-time optimized solutions.The robust multiple priority control problem was simplified as a polynomial cut problem with some reasonable assumptions and applied on a real-world intersection at Southern Ave. & 67 Ave. in Phoenix, AZ on February 22, 2010 and March 10, 2010. The roadside equipment (RSE) was installed in the traffic signal control cabinet and connected with a live traffic signal controller via Ethernet. With the support of Maricopa County's Regional Emergency Action Coordinating (REACT) team, three REACT vehicles were equipped with onboard equipments (OBE). Different priority scenarios were tested including concurrent requests, conflicting requests, and mixed requests. The experiments showed that the traffic controller was able to perform desirably under each scenario.Finally, a unified platoon-based mathematical formulation called PAMSCOD is presented to perform online arterial (network) traffic signal control while considering multiple travel modes in the IntelliDriveSM environment with high market penetration, including passenger vehicles. First, a hierarchical platoon recognition algorithm is proposed to identify platoons in real-time. This algorithm can output the number of platoons approaching each intersection. Second, a mixed-integer linear program (MILP) is solved to determine the future optimal signal plans based on the real-time platoon data (and the platoon request for service) and current traffic controller status. Deviating from the traditional common network cycle length, PAMSCOD aims to provide multi-modal dynamical progression (MDP) on the arterial based on the real-time platoon information. The integer feasible solution region is enhanced in order to reduce the solution times by assuming a first-come, first-serve discipline for the platoon requests on the same approach. Microscopic online simulation in VISSIM shows that PAMSCOD can easily handle two traffic modes including buses and automobiles jointly and significantly reduce delays for both modes, compared with SYNCHRO optimized plans.
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Han, Chunyang. "Robust Control of Teleoperated Unmanned Aerial Vehicles." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278212.
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In this thesis, we first use the reachability theory to develop algorithms for state predictionunder delayed state or output measurements. We next develop control strategies forcollision avoidance and trajectory tracking of UAVs based on the devised algorithms andthe model predictive control theory. Finally, simulations results for collision avoidanceand trajectory tracking problems are presented, for different communication delays,using a UAV model with 6 degrees of freedom.I denna avhandling använder vi först tillgänglighetsteorin för att utveckla algoritmerför tillståndsförutsägelse under fördröjda tillstånds- eller utgångsmätningar. Därefterutvecklar kontrollstrategier för undvikande av kollision och spårning av UAV: er baseradepå de planerade algoritmerna och modellen förutsägbar kontrollteori. Slutligenpresenteras simuleringsresultat för att undvika kollision och problem med spårningav banan, för olika kommunikationsförseningar, med en UAV-modell med 6 frihetsgrader.
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Andersson, Gabriella, and Johanna Dingfors. "Vägen till framtidens hållbara konsument : En kvalitativ studie om hur generation z uppfattar hållbarhetskommunikation i den svenska modebranschen." Thesis, Södertörns högskola, Institutionen för samhällsvetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-45906.
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With the increased focus on climate change, sustainability has become a common term for both organizations as well as consumers. The clothing industry is one of the industries that have the biggest negative impact on climate change. Still, the fast fashion business, based on cheap materials and low production costs, continues to thrive. The clothing companies stand before an increased review from society and are therefore forced to work with sustainability and acceptance. Depending on how the companies handle their communication with regards to sustainability, their consumers are put at risk of being subjectable to greenwashing, since the companies regard themselves to be more sustainable than they are. Generation Z consists of people born between the years of 1995 to 2005 and they were born into the so-called climate crisis. Generation Z is ultimately the generation that will live during the unpredictable future due to climate change. This makes the generation the most environmentally conscious generation yet. Still, the generation is the world’s largest group of consumers, and a large part of their identity lies within how they dress. This study aims to examine how generation Z, as an environmentally conscious group with a lot of purchasing power, perceives the Swedish fashion brand's communication about sustainability. The study is based on a quality method, using focus groups to gather data. This method is chosen since the aim is to analyze generation Z perception, feelings, and ideas. The theory studies terms within the roam of sustainability, both in the Swedish fashion business and as well as marketing. How Swedish fashion companies communicate their work on sustainability and how this is perceived by generation Z is presented via “a linear model of communication”. The result of the study shows that all the respondents have a similar perception of how confidence-inspiring the fashion business combination on sustainability is. Previous research has described generation Z as a consumer group that highly values sustainability, this is in line with the results of this study. The respondents describe that they consume sustainably by shopping second-hand but finds it hard to do sustainable choices when shopping for newly produced clothes. Fashion companies in the fast fashion sector that work with sustainability limited areas of the organization have low to no credibility from the respondents. The will to consume sustainably produced clothes is hindered by the fact that the respondents lack the trust for the actual sustainability in the products and production chain. The respondents seek companies with transparency, since thisincreases their trust and fulfills their will to consume sustainably.I takt med att vår klimatpåverkan ökar har hållbarhet blivit ett uppmärksammat begrepp hos såväl organisationer som hos konsumenter. Modebranschen är en av de branscher som har störst negativ påverkan på miljön, trots detta fortsätter den så kallade fast fashion-industrin, baserad på billiga material och tillverkningskostnader, att blomstra. Modeföretagen står samtidigt inför en ökad granskning av samhället och tvingas att arbeta med hållbarhet för att få acceptans. Beroende på hur företagen väljer att kommunicera sitt hållbarhetsarbete riskerar konsumenterna att bli utsatta för greenwashing, då företagen anser sig vara mer hållbara än vad de egentligen är. Generation z, personer födda mellan åren 1995–2005, är födda in i den så kallade klimatkrisen samt är också den generation som ska leva i en orolig framtid med växande klimatförändringar. Detta resulterar i att målgruppen är den hittills mest kritiska och miljömedvetna av alla generationer. Samtidigt är målgruppen världens största konsumentgrupp och är måna om att skapa sin identitet genom vad de klär sig i. Studien syftar till att undersöka hur generation z som köpkraftig och miljömedveten målgrupp uppfattar de svenska modeföretagens hållbarhetskommunikation. Forskarna har valt en kvalitativ forskningsmetod med fokusgrupper som insamlingsmetod eftersom studien syftar till att på ett djupgående sätt undersöka generation z:s uppfattningar, känslor och idéer. Teorin belyser begrepp som berör området hållbarhet i den svenska modebranschen och hållbar marknadsföring. Hur svenska modeföretag kommunicerar hållbarhetsarbetet och hur detta tolkas av generation z presenteras via kommunikationsmodellen “A linear model of communication”. Resultatet av studien visar att samtliga respondenter har liknande uppfattningar om hur förtroendeingivande modebranschens hållbarhetskommunikation är. Tidigare forskning beskriver generation z som en konsumentgrupp som värderar hållbarhet högt vilket stämmer överens med studiens resultat. Respondenterna beskriver att de handlar mycket hållbart i form av second hand men anser att det är svårt att göra hållbara val av nyproducerade plagg. Modeföretag verksamma inom fast fashion-industrin som arbetar med hållbarhet inom begränsade delar av organisationen har lågt eller inget förtroende hos representanterna. Viljan att handla nyproducerade hållbara plagg hindras av det faktum att respondenterna inte litar på graden av hållbarhet i produkterna och produktionskedjan. Greenwashing är ett begrepp samtliga respondenter är bekanta med vilket minskar förtroendet för företagen eftersom det är vanligt förekommande inom modebranschen. Samtliga respondenter efterlyser transparens hos företagen vilket skulle öka deras förtroende och vilja att konsumera hållbart.
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Brien, Christopher J. "Factorial linear model analysis." Title page, table of contents and summary only, 1992. http://thesis.library.adelaide.edu.au/public/adt-SUA20010530.175833.
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"February 1992" Bibliography: leaf 323-344. Electronic publication; Full text available in PDF format; abstract in HTML format. Develops a general strategy for factorial linear model analysis for experimental and observational studies, an iterative, four-stage, model comparison procedure. The approach is applicable to studies characterized as being structure-balanced, multitiered and based on Tjur structures unless the structure involves variation factors when it must be a regular Tjur structure. It covers a wide range of experiments including multiple-error, change-over, two-phase, superimposed and unbalanced experiments. Electronic reproduction.[Australia] :Australian Digital Theses Program,2001.
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Pimpalkhare, Mangesh S. "Linearly repeatered communication systems using optical amplifiers." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042010-020243/.
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Savic, Dejan, and Rasmus Tukia. "An Inquiry of Emotions Related to the Exploring, Gathering, Building and Fighting Activities in Video Games." Thesis, Södertörns högskola, Medieteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-44944.
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The four activities exploring, gathering, building and fighting are common across many genres of video games. Although these activities can come in many different forms such as fighting alone or in groups, against humans, beasts or fictional monsters, gathering sticks and stones to build a shelter or gathering cards to build the perfect deck, most games include at least one of these activities and some genres such as survival games include most of them. A test video game is used to allow participants to experience each activity and report discrete emotions felt during the activity. The purpose of this experiment is to find a link between each activity and a particular discrete emotion. Against our prediction, results indicate that rather than each activity being connected to a single discrete emotion, each activity leans towards either multiple positive emotions or multiple negative emotions.De fyra aktiviteterna utforska, samla, bygga samt strida förekommer i många genrer av spel. Även om dessa aktiviteter kan visa sig i många olika former, såsom t.ex. att strida ensam eller i grupper, emot människor, djur eller fiktionella monster, samla på sig pinnar och sten för att bygga ett skydd, eller samla på sig kort för att bygga den perfekta kortleken, innehåller de flesta spel åtminstone en av dessa aktiviteter. Vissa genrer såsom överlevnadsspel innehåller de flesta av dem. Ett test spel används för att tillåta deltagare att uppleva varje aktivitet och sedan rapportera diskreta känslor de känt under aktiviteten. Syftet med detta experiment är att hitta en länk mellan varje aktivitet och en viss diskret känsla. Förvånansvärt nog indikerar inte resultaten att inte att varje aktivitet är kopplad till en viss diskret känsla, men snarare att varje aktivitet lutar mot antingen ett flertal positiva känslor eller ett flertal negativa känslor.
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Townsend, Shane Martin Joseph. "Non-linear model predictive control." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301061.
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Waterman, Megan Janet Tuttle. "Linear Mixed Model Robust Regression." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27708.
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Mixed models are powerful tools for the analysis of clustered data and many extensions of the classical linear mixed model with normally distributed response have been established. As with all parametric models, correctness of the assumed model is critical for the validity of the ensuing inference. Model robust regression techniques predict mean response as a convex combination of a parametric and a nonparametric model fit to the data. It is a semiparametric method by which incompletely or incorrectly specified parametric models can be improved through adding an appropriate amount of a nonparametric fit. We apply this idea of model robustness in the framework of the linear mixed model. The mixed model robust regression (MMRR) predictions we propose are convex combinations of predictions obtained from a standard normal-theory linear mixed model, which serves as the parametric model component, and a locally weighted maximum likelihood fit which serves as the nonparametric component. An application of this technique with real data is provided.Ph. D.
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Fong, W. N. W. "Model-based methods for linear and non-linear audio signal enhancement." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599095.
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Owing to the random nature of audio signals, most of the enhancement methodologies reviewed in this work are based explicitly on a Bayesian model-based approach. Of these, the Kalman filter is the most commonly adopted enhancement strategy for a linear and Gaussian restoration problem. To copy with the general non-linear and non-Gaussian case, different filters such as the extended Kalman filter and the Gaussian sum filter have been proposed in the past few decades. As computing power increases, more computationally expensive simulation based approaches such as Monte Carlo methods have been suggested. The main focus of this work is on sequential estimation of the underlying clean signal and system parameters given some noisy observations under the Monte Carlo framework. This class of method is known as sequential Monte Carlo methods, also commonly referred to as the particle filter. In this work, different improvement strategies have been developed and described to improve on the generic particle filtering/smoothing algorithm. A block-based particle smoother is proposed to reduce the memory capacity required for the processing of lengthy datasets, such as audio signals. A Rao-Blackwellised particle smoother is developed to improve on the simulation results by reducing the dimension of the sampling space and thus the estimation variance. To cope with the non-linear restoration problem, a non-linear Rao-Blackwellised particle smoother is developed, which marginalises the parameter state, instead of the signal state as suggested earlier. Finally, we propose an efficient implementation of the suggested slow time-varying model under the sequential Monte Carlo framework for on-line joint signal and parameter estimation.
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Hagerud, Gustaf E. "A new non-linear GARCH model." Doctoral thesis, Stockholm : Economic Research Institute, Stockholm School of Economics [Ekonomiska forskningsinstitutet vid Handelshögsk.] (EFI), 1997. http://www.hhs.se/efi/summary/444.htm.
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Khawaja, Masud S. "The Mediating Role of Positive and Negative Emotional Attractors between Psychosocial Correlates of Doctor-Patient Relationship and Treatment Adherence in Type 2 Diabetes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1283995516.
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Strubbe, Mary. "My written thesis : an attempt at linear communication /." Online version of thesis, 1989. http://hdl.handle.net/1850/10958.
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Hosny, Sameh Shawky Ibrahim. "LARGE SCALE LINEAR OPTIMIZATION FOR WIRELESS COMMUNICATION SYSTEMS." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1482232039296433.
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Mickey, Joshua. "Random Linear Network Coding with Added Prefix Bits." Thesis, University of Louisiana at Lafayette, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10682547.
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The goal of this research was to completely describe Network Coding and Random Linear Network Coding functionality and operation; in addition, an added prospect of including prefix bits upon base RLNC protocol was proposed. The purpose of the added prefix bits was to obtain more control over an otherwise blind broadcast scheme in base RLNC. The addition of the prefix bits builds a decision-making algorithm check based upon the induction of knowledge of the entire system with each packet broadcasted from any respective node. These decision-making algorithms were able to produce efficiency constraints on the Source and respective Forwarding Nodes to increase throughput and QoS (Quality of Service).
The means by which the data to substantiate this theory was collected was through simulation models created in C++. Two models were created. One such model described base RLNC, while the second depicted RLNC behavior with added prefix bits. The final data showed some improvement with the second model with prefix bits as compared to the first model depicting base RLNC.
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Sandberg, Henrik. "Model Reduction for Linear Time-Varying Systems." Doctoral thesis, Lund University, Department of Automatic Control, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-74698.
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The thesis treats model reduction for linear time-varying systems. Time-varying models appear in many fields, including power systems, chemical engineering, aeronautics, and computational science. They can also be used for approximation of time-invariant nonlinear models. Model reduction is a topic that deals with simplification of complex models. This is important since it facilitates analysis and synthesis of controllers. The thesis consists of two parts. The first part provides an introduction to the topics of time-varying systems and model reduction. Here, notation, standard results, examples, and some results from the second part of the thesis are presented. The second part of the thesis consists of four papers. In the first paper, we study the balanced truncation method for linear time-varying state-space models. We derive error bounds for the simplified models. These bounds are generalizations of well-known time-invariant results, derived with other methods. In the second paper, we apply balanced truncation to a high-order model of a diesel exhaust catalyst. Furthermore, we discuss practical issues of balanced truncation and approximative discretization. In the third paper, we look at frequency-domain analysis of linear time-periodic impulse-response models. By decomposing the models into Taylor and Fourier series, we can analyze convergence properties of different truncated representations. In the fourth paper, we use the frequency-domain representation developed in the third paper, the harmonic transfer function, to generalize Bode's sensitivity integral. This result quantifies limitations for feedback control of linear time-periodic systems.QC 20120206
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Almelid, Øyvind. "Pion Condensation in the Linear Sigma Model." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12667.
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In this thesis we study the phase diagram of quantum chromodynamics in an effective low-energy theory at zero baryon chemical potential but finite temperature and isospin density. We investigate pion condensation at finite temperature and isospin chemical potential $mu_I$ in two different approximation schemes of the linear sigma model; the Large-$N$ and Hartree approximations at leading order. While being a simple model, the linear sigma model allows for phase transitions of both the first and second order, as well as crossover transitions at the physical point. The large-$N$ approximation yields results typical for mean-field approaches, including a second order phase transition with critical exponent $nu = frac{1}{2}$. At the physical point we find that pion condensation occurs below a threshold temperature $T_c(mu_I)$ only for $mu_I geq m_pi$. Due to the symmetry of the $O(N)$ expansion, the large-$N$ approximation also obeys Goldstone's theorem, yielding a massless Goldstone mode in the pion condensed phase.By contrast, we find a large violation of Goldstone's theorem in the Hartree approximation, with the Goldstone mode achieving a mass of $200 ~hbox{MeV} approx 1.4~ m_pi$. It is possible that the Hartree approximation's violation of symmetry makes the Goldstone mode tachyonic at low temperatures. However, it appears that the Hartree approximation yields a phase structure much more similar to what has been found in lattice studies, with a first order phase transition at high isospin densities and crossover transitions at lower densities. We have only been able to study the Hartree approximation under the condition that either the chiral condensate or the pion condensate is zero, however, and accurate probing of the phase diagram at the physical point is therefore not possible.
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Balabanov, Oleg. "Randomized linear algebra for model order reduction." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/668906.
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Solutions to high-dimensional parameter-dependent problems are in great demand in the contemporary applied science and engineering. The standard approximation methods for parametric equations can require computational resources that are exponential in the dimension of the parameter space, which is typically refereed to as the curse of dimensionality. To break the curse of dimensionality one has to appeal to nonlinear methods that exploit the structure of the solution map, such as projection-based model order reduction methods.
This thesis proposes novel methods based on randomized linear algebra to enhance the efficiency and stability of projection-based model order reduction methods for solving parameter-dependent equations. Our methodology relies on random projections (or random sketching). Instead of operating with high-dimensional vectors we first efficiently project them into a low-dimensional space. The reduced model is then efficiently and numerically stably constructed from the projections of the reduced approximation space and the spaces of associated residuals.
Our approach allows drastic computational savings in basically any modern computational architecture. For instance, it can reduce the number of flops and memory consumption and improve the efficiency of the data flow (characterized by scalability or communication costs). It can be employed for improving the efficiency and numerical stability of classical Galerkin and minimal residual methods. It can also be used for the efficient estimation of the error, and post-processing of the solution of the reduced order model. Furthermore, random sketching makes computationally feasible a dictionary-based approximation method, where for each parameter value the solution is approximated in a subspace with a basis selected from a dictionary of vectors.
We also address the efficient construction (using random sketching) of parameter-dependent preconditioners that can be used to improve the quality of Galerkin projections or for effective error certification for problems with ill-conditioned operators.
For all proposed methods we provide precise conditions on the random sketch to guarantee accurate and stable estimations with a user-specified probability of success. A priori estimates to determine the sizes of the random matrices are provided as well as a more effective adaptive procedure based on a posteriori estimates.Cette thèse introduit des nouvelles approches basées sur l’algèbre linéaire aléatoire pour améliorer l’efficacité et la stabilité des méthodes de réduction de modèles basées sur des projections pour la résolution d’équations dépendant de paramètres. Notre méthodologie repose sur des techniques de projections aléatoires ("random sketching") qui consistent à projeter des vecteurs de grande dimension dans un espace de faible dimension. Un modèle réduit est ainsi construit de manière efficace et numériquement stable à partir de projections aléatoires de l’espace d’approximation réduit et des espaces des résidus associés. Notre approche permet de réaliser des économies de calcul considérables dans pratiquement toutes les architectures de calcul modernes. Par exemple, elle peut réduire le nombre de flops et la consommation de mémoire et améliorer l’efficacité du flux de données (caractérisé par l’extensibilité ou le coût de communication). Elle peut être utilisée pour améliorer l’efficacité et la stabilité des méthodes de projection de Galerkin ou par minimisation de résidu. Elle peut également être utilisée pour estimer efficacement l’erreur et post-traiter la solution du modèle réduit. De plus, l’approche par projection aléatoire rend viable numériquement une méthode d’approximation basée sur un dictionnaire, où pour chaque valeur de paramètre, la solution est approchée dans un sous-espace avec une base sélectionnée dans le dictionnaire. Nous abordons également la construction efficace (par projections aléatoires) de préconditionneurs dépendant de paramètres, qui peuvent être utilisés pour améliorer la qualité des projections de Galerkin ou des estimateurs d’erreur pour des problèmes à opérateurs mal conditionnés. Pour toutes les méthodes proposées, nous fournissons des conditions précises sur les projections aléatoires pour garantir des estimations précises et stables avec une probabilité de succès spécifiée par l’utilisateur. Pour déterminer la taille des matrices aléatoires, nous fournissons des bornes a priori ainsi qu’une procédure adaptative plus efficace basée sur des estimations a posteriori
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Friedbaum, Jesse Robert. "Model Predictive Linear Control with Successive Linearization." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7063.
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Robots have been a revolutionizing force in manufacturing in the 20th and 21st century but have proven too dangerous around humans to be used in many other fields including medicine. We describe a new control algorithm for robots developed by the Brigham Young University Robotics and Dynamics and Robotics Laboratory that has shown potential to make robots less dangerous to humans and suitable to work in more applications. We analyze the computational complexity of this algorithm and find that it could be a feasible control for even the most complicated robots. We also show conditions for a system which guarantee local stability for this control algorithm.
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FERNANDES, CRISTIANO AUGUSTO COELHO. "LINEAR GROWTH BAYESIAN MODEL USING DISCOUNT FACTORS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1985. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9308@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOO objetivo principal desta dissertação é descrever e discutir o Modelo Bayesiano de Crescimento Linear Sazonal, formulação Estados múltiplos, utilizando descontos. As idéias originais deste modelo foram desenvolvidas por Ameen e Harrison. Na primeira parte do trabalho (capítulos 2 e 3) apresentamos idéias bem gerais sobre Séries Temporais e os principais modelos da literatura. A segunda parte (capítulos 4, 5 e 6) é dedicada à Estatística Bayesiana (conceitos gerais), ao MDL na sua formulação original, e ao nosso modelo de interesse. São apresentadas algumas sugestões operacionais e um fluxograma de operação do modelo, com vistas a uma futura implementação computacional.
The aim of this thesis is to discuss in details the Multiprocess Linear Grawth Bayesian Model for seasonal and/or nonseasonal series, using discount factors. The original formulation of this model was put forward recently by Ameen and Harrison. In the first part of the thesis (chapters 2 and 3) we show some general concepts related to time series and time series modelling, whereas in the second (chapters 4, 5 and 6) we formally presented / the Bayesian formulation of the proposed model. A flow chart and some optional parameter setings aiming a computational implementation is also presented.
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FARINAS, MAYTE SUAREZ. "THE LINEAR LOCAL-GLOBAL NEURAL NETWORK MODEL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3694@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICONesta tese apresenta-se o Modelo de Redes Neurais Globais- Locais (RNGL) dentro do contexto de modelos de séries temporais. Esta formulação abrange alguns modelos não- lineares já existentes e admite também o enfoque de Mistura de Especialistas. Dedica-se especial atenção ao caso de especialistas lineares, e são discutidos extensivamente aspectos teóricos do modelo: condições de estacionariedade, identificabilidade do modelo, existência, consistência e normalidade assintótica dos estimadores dos parâmetros. Considera-se também uma estratégia de construção do modelo e são discutidos os procedimentos numéricos de estimação, apresentando uma solução para o cálculo de valores iniciais. Finalmente, ilustra-se a metodologia apresentada em duas séries temporais reais, amplamente utilizada na literatura de modelos não lineares.
In this thesis, the Local Global Neural Networks model is proposed within the context of time series models. This formulation encompasses some already existing nonlinear models and also admits the Mixture of Experts approach. We place emphasis on the linear expert case and extensively discuss the theoretical aspects of the model: stationary conditions, existence, consistency and asymptotic normality of the parameter estimates, and model identifiability. A model building strategy is also considered and the whole procedure is illustrated with two real time-series.
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Mariotto, Angela Bacellar. "Empirical Bayes inference and the linear model." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47557.
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Gu, Wei. "Gauged Linear Sigma Model and Mirror Symmetry." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/90892.
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This thesis is devoted to the study of gauged linear sigma models (GLSMs) and mirror symmetry. The first chapter of this thesis aims to introduce some basics of GLSMs and mirror symmetry. The second chapter contains the author's contributions to new exact results for GLSMs obtained by applying supersymmetric localization. The first part of that chapter concerns supermanifolds. We use supersymmetric localization to show that A-twisted GLSM correlation functions for certain supermanifolds are equivalent to corresponding Atwisted GLSM correlation functions for hypersurfaces. The second part of that chapter defines associated Cartan theories for non-abelian GLSMs by studying partition functions as well as elliptic genera. The third part of that chapter focuses on N=(0,2) GLSMs. For those deformed from N=(2,2) GLSMs, we consider A/2-twisted theories and formulate the genuszero correlation functions in terms of Jeffrey-Kirwan-Grothendieck residues on Coulomb branches, which generalize the Jeffrey-Kirwan residue prescription relevant for the N=(2,2) locus. We reproduce known results for abelian GLSMs, and can systematically calculate more examples with new formulas that render the quantum sheaf cohomology relations and other properties manifest. We also include unpublished results for counting deformation parameters. The third chapter is about mirror symmetry. In the first part of the third chapter, we propose an extension of the Hori-Vafa mirrror construction [25] from abelian (2,2) GLSMs they considered to non-abelian (2,2) GLSMs with connected gauge groups, a potential solution to an old problem. We formally show that topological correlation functions of B-twisted mirror LGs match those of A-twisted gauge theories. In this thesis, we study two examples, Grassmannians and two-step flag manifolds, verifying in each case that the mirror correctly reproduces details ranging from the number of vacua and correlations functions to quantum cohomology relations. In the last part of the third chapter, we propose an extension of the Hori-Vafa construction [25] of (2,2) GLSM mirrors to (0,2) theories obtained from (2,2) theories by special tangent bundle deformations. Our ansatz can systematically produce the (0,2) mirrors of toric varieties and the results are consistent with existing examples which were produced by laborious guesswork. The last chapter briefly discusses some directions that the author would like to pursue in the future.Doctor of Philosophy
In this thesis, I summarize my work on gauged linear sigma models (GLSMs) and mirror symmetry. We begin by using supersymmetric localization to show that A-twisted GLSM correlation functions for certain supermanifolds are equivalent to corresponding A-twisted GLSM correlation functions for hypersurfaces. We also define associated Cartan theories for non-abelian GLSMs. We then consider N =(0,2) GLSMs. For those deformed from N =(2,2) GLSMs, we consider A/2-twisted theories and formulate the genus-zero correlation functions on Coulomb branches. We reproduce known results for abelian GLSMs, and can systematically compute more examples with new formulas that render the quantum sheaf cohomology relations and other properties are manifest. We also include unpublished results for counting deformation parameters. We then turn to mirror symmetry, a duality between seemingly-different two-dimensional quantum field theories. We propose an extension of the Hori-Vafa mirror construction [25] from abelian (2,2) GLSMs to non-abelian (2,2) GLSMs with connected gauge groups, a potential solution to an old problem. In this thesis, we study two examples, Grassmannians and two-step flag manifolds, verifying in each case that the mirror correctly reproduces details ranging from the number of vacua and correlations functions to quantum cohomology relations. We then propose an extension of the HoriVafa construction [25] of (2,2) GLSM mirrors to (0,2) theories obtained from (2,2) theories by special tangent bundle deformations. Our ansatz can systematically produce the (0,2) mirrors of toric varieties and the results are consistent with existing examples. We conclude with a discussion of directions that we would like to pursue in the future.
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Chen, Jinsong. "Semiparametric Methods for the Generalized Linear Model." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28012.
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The generalized linear model (GLM) is a popular model in many research areas. In the GLM, each outcome of the dependent variable is assumed to be generated from a particular distribution function in the exponential family. The mean of the distribution depends on the independent variables. The link function provides the relationship between the linear predictor and the mean of the distribution function. In this dissertation, two semiparametric extensions of the GLM will be developed. In the first part of this dissertation, we have proposed a new model, called a semiparametric generalized linear model with a log-concave random component (SGLM-L). In this model, the estimate of the distribution of the random component has a nonparametric form while the estimate of the systematic part has a parametric form. In the second part of this dissertation, we have proposed a model, called a generalized semiparametric single-index mixed model (GSSIMM). A nonparametric component with a single index is incorporated into the mean function in the generalized linear mixed model (GLMM) assuming that the random component is following a parametric distribution.
In the first part of this dissertation, since most of the literature on the GLM deals with the parametric random component, we relax the parametric distribution assumption for the random component of the GLM and impose a log-concave constraint on the distribution. An iterative numerical algorithm for computing the estimators in the SGLM-L is developed. We construct a log-likelihood ratio test for inference. In the second part of this dissertation, we use a single index model to generalize the GLMM to have a linear combination of covariates enter the model via a nonparametric mean function, because the linear model in the GLMM is not complex enough to capture the underlying relationship between the response and its associated covariates. The marginal likelihood is approximated using the Laplace method. A penalized quasi-likelihood approach is proposed to estimate the nonparametric function and parameters including single-index coe±cients in the GSSIMM. We estimate variance components using marginal quasi-likelihood. Asymptotic properties of the estimators are developed using a similar idea by Yu (2008). A simulation example is carried out to compare the performance of the GSSIMM with that of the GLMM. We demonstrate the advantage of my approach using a study of the association between daily air pollutants and daily mortality adjusted for temperature and wind speed in various counties of North Carolina.Ph. D.
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Zhao, Yonggang. "The general linear model for censored data." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1054781042.
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Alabiso, Audry. "Linear Mixed Model Selection by Partial Correlation." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1587142724497829.
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Dixon, Cheryl Annette. "Power Analysis for the Mixed Linear Model." VCU Scholars Compass, 1996. http://scholarscompass.vcu.edu/etd/4525.
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Power analysis is becoming standard in inference based research proposals and is used to support the proposed design and sample size. The choice of an appropriate power analysis depends on the choice of the research question, measurement procedures, design, and analysis plan. The "best" power analysis, however, will have many features of a sound data analysis. First, it addresses the study hypothesis, and second, it yields a credible answer.
Power calculations for standard statistical hypotheses based on normal theory have been defined for t-tests through the univariate and multivariate general linear models. For these statistical methods, the approaches to power calculations have been presented based on the exact or approximate distributions of the test statistics in question. Through the methods proposed by O'Brien and Muller (1993), the noncentrality parameter for the noncentral distribution of the test statistics for the univariate and multivariate general linear models is expressed in terms of its distinct components. This in tum leads to methods for calculating power which are efficient and easy to implement.
As more complex research questions are studied, more involved methods have been proposed to analyze data. One such method includes the mixed linear model. This research extends the approach to power calculation used for the general linear model to the mixed linear model. Power calculations for the mixed linear model will be based on the approximate F statistic for testing the mixed model's fixed effects proposed by Helms (1992). The noncentrality parameter of the approximate noncentral F for the mixed model will be written in terms of its distinct components so that a useful and efficient method for calculating power in the mixed model setting will be achieved. In this research, it has been found that the rewriting of the noncentrality parameter varies depending on study design. Thus, the noncentrality parameter for three specific cases of study design are derived.
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Orukpe, Patience Ebehiremen. "Model predictive control for linear time invariant systems using linear matrix inequality techniques." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509510.
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Abraham, Anita Ann Edwards Lloyd J. "Model selection methods in the linear mixed model for longitudinal data." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1859.
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Thesis (DrPH)--University of North Carolina at Chapel Hill, 2008.Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Public Health in the Department of Biostatistics, School of Public Health." Discipline: Biostatistics; Department/School: Public Health.
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Bai, Xue. "Robust linear regression." Kansas State University, 2012. http://hdl.handle.net/2097/14977.
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Master of ScienceDepartment of Statistics
Weixin Yao
In practice, when applying a statistical method it often occurs that some observations deviate from the usual model assumptions. Least-squares (LS) estimators are very sensitive to outliers. Even one single atypical value may have a large effect on the regression parameter estimates. The goal of robust regression is to develop methods that are resistant to the possibility that one or several unknown outliers may occur anywhere in the data. In this paper, we review various robust regression methods including: M-estimate, LMS estimate, LTS estimate, S-estimate, [tau]-estimate, MM-estimate, GM-estimate, and REWLS estimate. Finally, we compare these robust estimates based on their robustness and efficiency through a simulation study. A real data set application is also provided to compare the robust estimates with traditional least squares estimator.
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Zheng, Gan. "Optimization in linear multiuser MIMO systems." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557923.
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Zheng, Gan, and 鄭淦. "Optimization in linear multiuser MIMO systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557923.
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AMARAL, LUIZ FELIPE MOREIRA DO. "USING LINEAR AND NON-LINEAR APPROACHES TO MODEL THE BRAZILIAN ELECTRICITY SPOT PRICE SERIES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3727@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORNesta dissertação, estratégias de modelagem são apresentadas envolvendo modelos de séries temporais lineares e não lineares para modelar a série do preço spot no mercado elétrico brasileiro. Foram usados, dentre os lineares, os modelos ARIMA(p,d,q) proposto por Box, Jenkins e Reinsel (1994) e os modelos de regressão dinâmica. Dentre os não lineares, o modelo escolhido foi o STAR desenvolvido, inicialmente, por Chan e Tong (1986) e, posteriormente, por Teräsvista (1994). Para este modelo, testes do tipo Multiplicador de Lagrange foram usados para testar linearidade, bem como para avaliar os modelos estimados. Além disso, foi também utilizada uma proposta para os valores iniciais do algoritmo de otimização, desenvolvido por Franses e Dijk (2000). Estimativas do filtro de Kalman suavizado foram usadas para substituir os valores da série de preço durante o racionamento de energia ocorrido no Brasil.
In this dissertation, modeling strategies are presented involving linear and non-linear time series models to model the spot price of Brazil s electrical energy market. It has been used, among the linear models, the modeling approach of Box, Jenkins and Reinsel (1994) i.e., ARIMA(p,d,q) models, and dynamic regression. Among the non-linear ones, the chosen model was the STAR developed, initially, by Chan and Tong (1986) and, later, by Teräsvirta (1994). For this model, the Lagrange Multipliers test, to measure the degree of non linearity of the series , as well as to evaluate the estimated model was used. Moreover, it was also used a proposal for the initial values of the optimization algorithm, developed by Franses and Dijk (2000). The smoothed Kalman filter estimates were used in order to provide values for the spot price series during the energy shortage period.
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McPhee, Craig. "Development and characterisation of synthetic model lipid membranes under linear and non-linear microscopy." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/111884/.
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Lipid domains provide a framework for localised functionality of the cellular membrane through transient coordination of certain lipids and membrane proteins into structurally distinct, stabilised heterogeneous membrane regions. Present experimental studies fall short of conclusively proving lipid domain existence within the plasma membrane due to the lack of label-free, chemically sensitive nanoscale detection. Herein, I present my progress towards developing novel, label-free optical microscopy techniques to over- come these limitations. Giant unilamellar vesicles (GUVs) represent a simple model of cellular membranes and are well suited for the study of lipid domains. In this thesis, I discuss the demonstration of a novel, label free method to directly assess GUV lamellarity: Quantitative differential interference contrast microscopy (qDIC). Under qDIC, a contrast image is produced which encodes the difference in optical phase (hence optical path length) after propagation through two adjacent points of the sample. I show that, with appropriate data analysis applied to qDIC contrast images, we are able to measure membrane lamellarity directly with sub-nm precision. I then demonstrate the application of this method to static synthetic membranes exhibiting lipid domains: Planar Lipid Bilayer Patches (PLBPs). Sub-nm thickness differences (∼9Å) attributable to coexisting lipid domains are resolved and quantified. Overall, these results demonstrate that label free qDIC is a rapid, non-perturbing, sensitive and accurate method, providing an alternative to fluorescence microscopy, for quantitative studies of lipid domains in model membranes. Furthermore, I discuss correlative qDIC and Coherent Anti-Stokes Ra- man scattering microscopy (CARS) of PLBPs with lipid domains. CARS microscopy has emerged in the last decade as a powerful, chemically specific multi-photon imaging method which overcomes the sensitivity and speed limitations of spontaneous Raman scattering, and enables rapid quantitative analysis of lipids label-free. I demonstrate application of broadband hyper-spectral CARS imaging over the CH 2,3 stretching vibrational resonances, combined with in-house developed phase-corrected Kramers Krönig (PCKK) analysis, which allowed us to resolve and quantify the chemical components of lipid domains at the single bilayer level. Stimulated Raman loss (SRL) microscopy is an alternative, chemically specific, non-linear imaging modality recently implemented within our research group. In contrast to CARS microscopy, SRL rejects non-resonant background providing high contrast imaging of single lipid bilayers comparable to fluorescence imaging. I demonstrate early application of SRL at the single bilayer level across the CH 2,3 stretch region. During this project a number of notable achievements have been made. A novel qDIC method has been developed and utilised. CARS microscopy has been applied to determine lipid liquid phase at both single frequency and hyper-spectral imaging modalities. SRL microscopy has then been applied, demonstrating superior contrast to that seen under CARS. These studies form the foundation for further chemically specific investigation.
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Hernandez, Erika Lyn. "Parameter Estimation in Linear-Linear Segmented Regression." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3551.pdf.
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Goparaju, Manoj Kumar. "Parametric fault model for linear threshold logic networks /." Available to subscribers only, 2005. http://proquest.umi.com/pqdweb?did=1079666531&sid=27&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Tang, On-yee, and 鄧安怡. "Estimation for generalized linear mixed model via multipleimputations." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B30687652.
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Lee, Jaehwa. "Linear and nonlinear distributed economic model predictive control." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23936.
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Model predictive control (MPC), also called receding horizon control, is a control technique to determine control actions for systems by using mathematical optimization theory such as linear or nonlinear programming. It is widely adopted for industrial applications because of its capability of dealing with constraints. For implementation of MPC we solve an on-line optimization problem which minimizes the object function with respect to the given constraints. We commonly adopt convex cost function, which is minimum at the set-point, since by minimizing this cost over horizons we can obtain the convergence of states to the desired set-point. This thesis, however, considers MPC with economically defined objective functions, and implements it in decentralized manner. The key difference of the economic objectives, acquired from the actual value of plants to operate, is that they are not necessarily minimum at the best steady-state, which we decide as the set-point for the state for the operations. Distributed system usually refers to a large-scale system which consists of multiple subsystems interacting with each other. In cooperative MPC which we deal with throughout this thesis, all the subsystems share and optimize the common cost. The main difficulty of this control arises from the coupled inputs and states between subsystems, and the effect between them. While computing consideration on state estimation of other subsystems should be taken into account for the controller design, so large computational burden is unavoidable. We divide the computation into several small problems, and suggest the iterations between the subsystems for the improvement of performance. For linear systems the convex sum of the computation, or estimation, of each subsystem generates the feasible input sequence at any number of iteration. Furthermore, we define and investigate individual feasibility for nonlinear systems. For both cases we prove the iterates converge to the Nash equilibria under some assumptions including asymptotic average constraints. For application example, we investigate the consecutive-competitive reactions, whose resultant substance and byproduct compete to be produced more through the reactions, with numerical simulations.
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Bunea, Florentina. "A model selection approach to partially linear regression /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8971.
Full text
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Saleem, Aban, and Jacob Blomgren. "Modelling Pupils’ Grades with Multiple Linear Regression Model." Thesis, KTH, Matematisk statistik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-275672.
Full textAbstract:
This thesis was based on the subjects of mathematical statistics and industrial economics and management in order to analyze the grades of pupils in the final year of elementary school. The purpose was to find out what variables had a statistically significant impact on pupils’ final grades so that municipalities and schools could better understand what variables are important when trying to improve the average school results. A multiple regression model was used on data, obtained from the database of Skolverket, in order to examine what variables were statistically important. The final regression model acquired through a model reduction procedure showed that mostly structural covariates such as the academic background of pupils, percentage of female pupils and the percentage with Swedish background had a statistically significant impact on the academic performances of the students. R2 adjusted of the final model was 0.5289. The multiple regression model was discussed by referencing to previous research. In addition, the strategic management performance framework known as Balanced Scorecard which was introduced by Robert S. Kaplan and David P. Norton was used to discuss relevant key performance indicators to achieve the strategic objectives of schools.Detta examensarbete, inom ämnet för matematisk statistik och industriell ekonomi, genomfördes med syftet att analysera avgångsbetygen för år 9 i den svenska skolan. Syftet var att förstå vilka variabler som hade en statistisk signifikant påverkan på elevers avgångsbetyg, så kommuner kan förstå vilka variabler som är viktiga för att förbättra de genomsnittliga skolresultaten. En regressionsanalys utfördes, på data från Skolverket, för att se vilka variabler som var statistiskt signifikanta. Den slutgiltiga regressionsmodellen, erhållen genom iterativ reducering av variabler, visade att främst strukturella kovariat, som akademisk bakgrund hos elever, andel kvinnliga studenter och andel studenter med svensk bakgrund hade en signifikant betydelse på studenters akademiska resultat. Justerad R2 var 0.5289 för den slutgiltiga modellen. I diskussionen utvärderades modellen utifrån tidigare forskning. Vidare användes teorin om balanserat styrkort, utvecklat av Robert S. Kaplan och David P. Norton, för att diskutera relevanta nyckeltal för att uppnå strategiska mål för skolan.
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Magruder, Caleb Clarke III. "Model Reduction of Linear Time-Periodic Dynamical Systems." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23112.
Full textAbstract:
Few model reduction techniques exist for dynamical systems whose parameters vary with time. We have particular interest here in linear time-periodic dynamical systems; we seek a structure-preserving algorithm for model reduction of linear time-periodic (LTP) dynamical systems of large scale that generalizes from the linear time-invariant (LTI) model reduction problem.We extend the familiar LTI system theory to analogous concepts in the LTP setting. First, we represent the LTP system as a convolution operator of a bivariate periodic kernel function. The kernel suggests a representation of the system as a frequency operator, called the Harmonic Transfer Function. Second, we exploit the Hilbert space structure of the family of LTP systems to develop necessary conditions for optimal approximations.
Additionally, we show an a posteriori error bound written in terms of the $\\mathcal H_2$ norm of related LTI multiple input/multiple output system. This bound inspires an algorithm to construct approximations of reduced order.
To verify the efficacy of this algorithm we apply it to three models: (1) fluid flow around a cylinder by a finite element discretization of the Navier-Stokes equations, (2) thermal diffusion through a plate modeled by the heat equation, and (3) structural model of component 1r of the Russian service module of the International Space Station.
Master of Science
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Kim, Tae-Hyoung. "Robust model predictive control for constrained linear systems." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/143898.
Full textAbstract:
Kyoto University (京都大学)0048
新制・課程博士
博士(情報学)
甲第12450号
情博第204号
新制||情||44(附属図書館)
24286
UT51-2006-J441
京都大学大学院情報学研究科システム科学専攻
(主査)教授 杉江 俊治, 教授 酒井 英昭, 教授 熊本 博光
学位規則第4条第1項該当
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Khan, Md Jafar Ahmed. "Robust linear model selection for high-dimensional datasets." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/31082.
Full textAbstract:
This study considers the problem of building a linear prediction model when the number of candidate covariates is large and the dataset contains a fraction of outliers and other contaminations that are difficult to visualize and clean. We aim at predicting the future non-outlying cases. Therefore, we need methods that are robust and scalable at the same time.
We consider two different strategies for model selection: (a) one-step model building and (b) two-step model building. For one-step model building, we robustify the step-by-step algorithms forward selection (FS) and stepwise (SW), with robust partial F-tests as stopping rules.
Our two-step model building procedure consists of sequencing and segmentation. In sequencing, the input variables are sequenced to form a list such that the good predictors are likely to appear in the beginning, and the first m variables of the list form a reduced set for further consideration. For this step we robustify Least Angle Regression (LARS) proposed by Efron, Hastie, Johnstone and Tibshirani (2004). We use bootstrap to stabilize the results obtained by robust LARS, and use "learning curves" to determine the size of the reduced set.
The second step (of the two-step model building procedure) - which we call segmentation - carefully examines subsets of the covariates in the reduced set in order to select the final prediction model. For this we propose a computationally suitable robust cross-validation procedure. We also propose a robust bootstrap procedure for segmentation, which is similar to the method proposed by Salibian-Barrera and Zamar (2002) to conduct robust inferences in linear regression.
We introduce the idea of "multivariate-Winsorization" which we use for robust data cleaning (for the robustification of LARS). We also propose a new correlation estimate which we call the "adjusted-Winsorized correlation estimate". This estimate is consistent and has bounded influence, and has some advantages over univariate-Winsorized correlation estimate (Huber 1981 and Alqallaf 2003).Science, Faculty of
Statistics, Department of
Graduate