Placement and Movement Episodes Detection using Mobile Trajectories Data

Teostatud töö eesmärgiks on tuvastada asukohaandmetest seisu- ning liikumisepisoode kasutades selleks trajektoori ülekattuvusmaatriksit. Antud töös kasutatud andmed on väga hajusad nii ajalises kui ka geograafilises mõttes. Seetõttu on antud ülesanne suur väljakutse. Välja pakutud lahenduse raames teostati andmeanalüüs mille raames tuvastati kasutajatele tähtsad asukohad ning pakuti välja algoritm, mille abil tuvastda seisu- ning liikumisepisoodid. Andmete analüüsimiseks ning visualiseerimiseks kasutati R-i.This thesis presents a trajectory episode matrix to enable the detection of placement and movement episodes from mobile location data. The data used in this work is very sparse in time and space. Therefore, the estimation of user’s placement and movement patterns poses a big challenge. The presented approach performs data analysis to find meaningful locations and introduces an algorithm to detect movement and placement episodes. To perform the analysis and visualize the results a statistical analysis tool was developed with R. The work done as a result of this thesis can be used to improve the identification of the meaningful locations and to help predicting the semantic meanings of mobile user’s patterns

An enhanced weighted performance-based handover parameter optimization algorithm for LTE networks

This article introduces an enhanced version of previously developed self-optimizing algorithm that controls the handover (HO) parameters of a long-term evolution base station in order to diminish and prevent the negative effects that can be introduced by HO (radio link failures, HO failures and ping-pong HOs) and thus improve the overall network performance. The default algorithm selects the best hysteresis and time-to-trigger combination based on the current network status. The enhancement proposed here aims to maximize the gain provided by the algorithm by improving its convergence time. The effects of this enhancement have been studied in a rural scenario setting and compared to the original algorithm; the results show a clear improvement, faster convergence, and better network performance, because of the enhancement

Handover in Mobile WiMAX Networks: The State of Art and Research Issues

The next-generation Wireless Metropolitan Area Networks, using the Worldwide Interoperability for Microwave Access (WiMAX) as the core technology based on the IEEE 802.16 family of standards, is evolving as a Fourth-Generation (4G) technology. With the recent introduction of mobility management frameworks in the IEEE 802.16e standard, WiMAX is now placed in competition to the existing and forthcoming generations of wireless technologies for providing ubiquitous computing solutions. However, the success of a good mobility framework largely depends on the capability of performing fast and seamless handovers irrespective of the deployed architectural scenario. Now that the IEEE has defined the Mobile WiMAX (IEEE 802.16e) MAC-layer handover management framework, the Network Working Group (NWG) of the WiMAX Forum is working on the development of the upper layers. However, the path to commercialization of a full-fledged WiMAX mobility framework is full of research challenges. This article focuses on potential handover-related research issues in the existing and future WiMAX mobility framework. A survey of these issues in the MAC, Network and Cross-Layer scenarios is presented along with discussion of the different solutions to those challenges. A comparative study of the proposed solutions, coupled with some insights to the relevant issues, is also included

Arabidopsis thaliana dehydroascorbate reductase 2 : conformational flexibility during catalysis

Dehydroascorbate reductase (DHAR) catalyzes the glutathione (GSH)-dependent reduction of dehydroascorbate and plays a direct role in regenerating ascorbic acid, an essential plant antioxidant vital for defense against oxidative stress. DHAR enzymes bear close structural homology to the glutathione transferase (GST) superfamily of enzymes and contain the same active site motif, but most GSTs do not exhibit DHAR activity. The presence of a cysteine at the active site is essential for the catalytic functioning of DHAR, as mutation of this cysteine abolishes the activity. Here we present the crystal structure of DHAR2 from Arabidopsis thaliana with GSH bound to the catalytic cysteine. This structure reveals localized conformational differences around the active site which distinguishes the GSH-bound DHAR2 structure from that of DHAR1. We also unraveled the enzymatic step in which DHAR releases oxidized glutathione (GSSG). To consolidate our structural and kinetic findings, we investigated potential conformational flexibility in DHAR2 by normal mode analysis and found that subdomain mobility could be linked to GSH binding or GSSG release

Self organization in 3GPP long term evolution networks

Mobiele en breedbandige internettoegang is realiteit. De internetgeneratie vindt het immers normaal om overal breedbandige internettoegang te hebben. Vandaag zijn er al 5,9 miljard mobiele abonnees ( 87% van de wereldbevolking) en 20% daarvan hebben toegang tot een mobiele breedbandige internetverbinding. Dit wordt aangeboden door 3G (derde generatie) technologieën zoals HSPA (High Speed Packet Access) en 4G (vierde generatie) technologieën zoals LTE (Long Term Evolution). De vraag naar hoogkwalitatieve diensten stelt de mobiele netwerkoperatoren en de verkopers van telecommunicatieapparatuur voor nieuwe uitdagingen: zij moeten nieuwe oplossingen vinden om hun diensten steeds sneller en met een hogere kwaliteit aan te bieden. De nieuwe LTE-standaard brengt niet alleen hogere pieksnelheden en kleinere vertragingen. Het heeft daarnaast ook nieuwe functionaliteiten in petto die zeer aantrekkelijk zijn voor de mobiele netwerkoperator: de integratie van zelfregelende functies die kunnen ingezet worden bij de planning van het netwerk, het uitrollen van een netwerk en het controleren van allerhande netwerkmechanismen (o.a. handover, spreiding van de belasting over de cellen). Dit proefschrift optimaliseert enkele van deze zelfregelende functies waardoor de optimalisatie van een mobiel netwerk snel en automatisch kan gebeuren. Hierdoor verwacht men lagere kosten voor de mobiele operator en een hogere kwaliteit van de aangeboden diensten

Cell identity allocation and optimisation of handover parameters in self-organised LTE femtocell networks

A thesis submitted to the University of Bedfordshire in partial ful lment of the requirements for the degree of Doctor of PhilosophyFemtocell is a small cellular base station used by operators to extend indoor service coverage and enhance overall network performance. In Long Term Evolution (LTE), femtocell works under macrocell coverage and combines with the macrocell to constitute the two-tier network. Compared to the traditional single-tier network, the two-tier scenario creates many new challenges, which lead to the 3rd Generation Partnership Project (3GPP) implementing an automation technology called Self-Organising Network (SON) in order to achieve lower cost and enhanced network performance. This thesis focuses on the inbound and outbound handovers (handover between femtocell and macrocell); in detail, it provides suitable solutions for the intensity of femtocell handover prediction, Physical Cell Identity (PCI) allocation and handover triggering parameter optimisation. Moreover, those solutions are implemented in the structure of SON. In order to e ciently manage radio resource allocation, this research investigates the conventional UE-based prediction model and proposes a cell-based prediction model to predict the intensity of a femtocell's handover, which overcomes the drawbacks of the conventional models in the two-tier scenario. Then, the predictor is used in the proposed dynamic group PCI allocation approach in order to solve the problem of PCI allocation for the femtocells. In addition, based on SON, this approach is implemented in the structure of a centralised Automated Con guration of Physical Cell Identity (ACPCI). It overcomes the drawbacks of the conventional method by reducing inbound handover failure of Cell Global Identity (CGI). This thesis also tackles optimisation of the handover triggering parameters to minimise handover failure. A dynamic hysteresis-adjusting approach for each User Equipment (UE) is proposed, using received average Reference Signal-Signal to Interference plus Noise Ratio (RS-SINR) of the UE as a criterion. Furthermore, based on SON, this approach is implemented in the structure of hybrid Mobility Robustness Optimisation (MRO). It is able to off er the unique optimised hysteresis value to the individual UE in the network. In order to evaluate the performance of the proposed approach against existing methods, a System Level Simulation (SLS) tool, provided by the Centre for Wireless Network Design (CWiND) research group, is utilised, which models the structure of two-tier communication of LTE femtocell-based networks

Structural and functional studies of mitochondrial NADH:ubiquinone oxidoreductase (complex I)

NADH:ubiquinone oxidoreductase (complex I) is the largest and most complicated enzyme in the mitochondrial electron transfer chain. It catalyses the oxidation of NADH and the reduction of ubiquinone, coupled to the translocation of protons across the mitochondrial inner membrane, maintaining the proton motive force used for ATP synthesis. Complex I is the least understood of the respiratory enzymes; although the mechanisms of NADH oxidation and intramolecular electron transfer are gradually becoming appreciated, the mechanisms of quinone binding and reduction and proton translocation remain unknown. Complex I dysfunction has been implicated in a wide range of pathologies including mitochondrial diseases such as Leigh’s disease, as well as neurodegenerative diseases such as Alzheimer’s and Parkinson’s. The work described in the first part of this thesis is aimed at elucidating the structure of either a subcomplex of mitochondrial complex I, or of the intact enzyme itself. A comprehensive investigation revealed that hydrophilic subcomplexes of complex I from bovine heart mitochondria are not suitable for use as models of the intact enzyme. Attempts to prepare intact complex I of sufficient quality for structural work were successful; however, results from a large set of crystallization trials were disappointing. The second part of this thesis describes three studies of the function and mechanism of complex I from bovine heart mitochondria. First, the flavin mononucleotide, the site of NADH oxidation, was identified as the site of the ‘inhibitor-insensitive’ NADH:ubiquinone oxidoreduction reaction. The formation of semiquinones initiates redox cycling reactions with oxygen, producing vast amounts of reactive oxygen species; further studies revealed that other oxidants, such as paraquat, also react at the flavin site and initiate redox cycling reactions. Second, kinetic studies showed that the reaction between NADH and positively charged oxidants such as HAR (hexaammineruthenium (III)) proceeds by an unusual ternary reaction mechanism at the flavin site of complex I. Finally, double electron-electron resonance spectroscopy was used to show unambiguously that iron sulphur cluster 4Fe[TY]1 gives rise to electron paramagnetic resonance signal N4; the data provide an alternating potential energy profile for electron transfer along the cluster chain between the flavin and the quinone-binding site.This work was supported by the Medical Research Counci

Integrated Electronics for Wireless Imaging Microsystems with CMUT Arrays

Integration of transducer arrays with interface electronics in the form of single-chip CMUT-on-CMOS has emerged into the field of medical ultrasound imaging and is transforming this field. It has already been used in several commercial products such as handheld full-body imagers and it is being implemented by commercial and academic groups for Intravascular Ultrasound and Intracardiac Echocardiography. However, large attenuation of ultrasonic waves transmitted through the skull has prevented ultrasound imaging of the brain. This research is a prime step toward implantable wireless microsystems that use ultrasound to image the brain by bypassing the skull. These microsystems offer autonomous scanning (beam steering and focusing) of the brain and transferring data out of the brain for further processing and image reconstruction. The objective of the presented research is to develop building blocks of an integrated electronics architecture for CMUT based wireless ultrasound imaging systems while providing a fundamental study on interfacing CMUT arrays with their associated integrated electronics in terms of electrical power transfer and acoustic reflection which would potentially lead to more efficient and high-performance systems. A fully wireless architecture for ultrasound imaging is demonstrated for the first time. An on-chip programmable transmit (TX) beamformer enables phased array focusing and steering of ultrasound waves in the transmit mode while its on-chip bandpass noise shaping digitizer followed by an ultra-wideband (UWB) uplink transmitter minimizes the effect of path loss on the transmitted image data out of the brain. A single-chip application-specific integrated circuit (ASIC) is de- signed to realize the wireless architecture and interface with array elements, each of which includes a transceiver (TRX) front-end with a high-voltage (HV) pulser, a high-voltage T/R switch, and a low-noise amplifier (LNA). Novel design techniques are implemented in the system to enhance the performance of its building blocks. Apart from imaging capability, the implantable wireless microsystems can include a pressure sensing readout to measure intracranial pressure. To do so, a power-efficient readout for pressure sensing is presented. It uses pseudo-pseudo differential readout topology to cut down the static power consumption of the sensor for further power savings in wireless microsystems. In addition, the effect of matching and electrical termination on CMUT array elements is explored leading to new interface structures to improve bandwidth and sensitivity of CMUT arrays in different operation regions. Comprehensive analysis, modeling, and simulation methodologies are presented for further investigation.Ph.D

High-precision fluorescence photometry for real-time biomarkers detection

Les derniers évènements planétaires et plus particulièrement l'avènement sans précédent du nouveau coronavirus augmente la demande pour des appareils de test à proximité du patient. Ceux-ci fonctionnent avec une batterie et peuvent identifier rapidement des biomarqueurs cibles. Pareils systèmes permettent aux utilisateurs, disposant de connaissances limitées en la matière, de réagir rapidement, par exemple dans la détection d'un cas positif de COVID-19. La mise en œuvre de l'élaboration d'un tel instrument est un projet multidisciplinaire impliquant notamment la conception de circuits intégrés, la programmation, la conception optique et la biologie, demandant tous une maîtrise pointue des détails. De plus, l'établissement des spécifications et des exigences pour mesurer avec précision les interactions lumière-échantillon s'additionnent au besoin d'expérience dans la conception et la fabrication de tels systèmes microélectriques personnalisés et nécessitent en elles-mêmes, une connaissance approfondie de la physique et des mathématiques. Ce projet vise donc à concevoir et à mettre en œuvre un appareil sans fil pour détecter rapidement des biomarqueurs impliqués dans des maladies infectieuses telles que le COVID-19 ou des types de cancers en milieu ambulatoire. Cette détection se fait grâce à des méthodes basées sur la fluorescence. La spectrophotométrie de fluorescence permet aux médecins d'identifier la présence de matériel génétique viral ou bactérien tel que l'ADN ou l'ARN et de les caractériser. Les appareils de paillasse sont énormes et gourmand énergétiquement tandis que les spectrophotomètres à fluorescence miniatuarisés disponibles dans le commerce sont confrontés à de nombreux défis. Ces appareils miniaturisés ont été découverts en tirant parti des diodes électroluminescentes (DEL) à semi-conducteurs peu coûteuses et de la technologie des circuits intégrés. Ces avantages aident les scientifiques à réduire les erreurs possibles, la consommation d'énergie et le coût du produit final utilisé par la population. Cependant, comme leurs homologues de paillasse, ces appareils POC doivent quantifier les concentrations en micro-volume d'analytes sur une large gamme de longueurs d'onde suivant le cadre d'une économie en ressources. Le microsystème envisagé bénéficie d'une approche de haute précision pour fabriquer une puce microélectronique CMOS. Ce procédé se fait de concert avec un boîtier personnalisé imprimé en 3D pour réaliser le spectrophotomètre à la fluorescence nécessaire à la détection quantitative d'analytes en microvolume. En ce qui a trait à la conception de circuits, une nouvelle technique de mise à auto-zeroing est appliquée à l'amplificateur central, celui-ci étant linéarisé avec des techniques de recyclage et de polarisation adaptative. Cet amplificateur central est entièrement différentiel et est utilisé dans un amplificateur à verrouillage pour récupérer le signal d'intérêt éclipsé par le bruit. De plus, l'augmentation de la sensibilité de l'appareil permet des mesures quantitatives avec des concentrations en micro-volume d'analytes ayant moins d'erreurs de prédiction de concentration. Cet avantage cumulé à une faible consommation d'énergie, un faible coût, de petites dimensions et un poids léger font de notre appareil une solution POC prometteuse dans le domaine de la spectrophotométrie de fluorescence. La validation de ce projet s'est fait en concevant, fabriquant et testant un prototype discret et sans fil. Son article de référence a été publié dans IEEE LSC 2018. Quant à la caractérisation et l'interprétation du prototype d'expériences in vitro à l'aide d'une interface MATLAB personnalisée, cet article a été publié dans IEEE Sensors journal (2021). Les circuits intégrés et les photodétecteurs ont été fabriqués ont été conçus et fabriqués par Cadence en 2019. Relativement aux solutions de circuit proposées, elles ont été fabriquées avec la technologie CMOS 180 nm et publiées lors de la conférence IEEE MWSCAS 2020. Tout comme cette dernière contribution, les expériences in vitro avec le dispositif proposé incluant la puce personnalisée et le boîtier imprimé en 3D ont été réalisés et les résultats électriques et optiques ont été soumis au IEEE Journal of Solid-State Circuits (JSSC 2022).The most recent and unprecedented experience of the novel coronavirus increases the demand for battery-operated near-patient testing devices that can rapidly identify the target biomarkers. Such systems enable end-users with limited resources to quickly get feedback on various medical tests, such as detecting positive COVID-19 cases. Implementing such a device is a multidisciplinary project dealing with multiple areas of expertise, including integrated circuit design, programming, optical design, and biology, each of which needs a firm grasp of details. Alongside the need for experience in designing and manufacturing custom microelectronic systems, establishing the specifications and requirements to precisely measure the light-sample interactions requires an in-depth knowledge of physics and mathematics. This project aims to design and implement a wireless point-of-care (POC) device to rapidly detect biomarkers involved in infectious diseases such as COVID-19 or different types of cancers in an ambulatory setting using fluorescence-based methods. Fluorescence spectrophotometry allows physicians to identify and characterize viral or bacterial genetic materials such as DNAs or RNAs. The benchtop devices that are currently available are bulky and power-hungry, whereas the commercially available miniaturized fluorescence spectrophotometers are facing many challenges. Many of these difficulties have been resolved in literature thanks to inexpensive semiconductor light-emitting diodes (LEDs) and integrated circuits technology. Such advantages aid scientists in decreasing the size, power consumption, and cost of the final product for end-users. However, like the benchtop counterparts, such POC devices must quantify micro-volume concentrations of analytes across a wide wave length range under an economy of resources. The envisioned microsystem benefits from a high-precision approach to fabricating a CMOS microelectronic chip combined with a custom 3D-printed housing. This implementation results in a fluorescence spectrophotometer for qualitative and quantitative detection of micro-volume analytes. In terms of circuit design, a novel switched-biasing ping-pong auto-zeroed technique is applied to the core amplifier, linearized with recycling and adaptive biasing techniques. The fully differential core amplifier is utilized within a lock-in amplifier to retrieve the signal of interest overshadowed by noise. Increasing the device's sensitivity allows quantitative measurements down to micro-volume concentrations of analytes with less concentration prediction error. Such an advantage, along with low-power consumption, low cost, low weight, and small dimensions, make our device a promising POC solution in the fluorescence spectrophotometry area. The approach of this project was validated by designing, fabricating, and testing a discrete and wireless prototype. Its conference paper was published in IEEE LSC 2018, and the prototype characterization and interpretation of in vitro experiments using a custom MATLAB interface were published in IEEE Sensors Journal (2021). The integrated circuits and photodetectors were designed and fabricated by the Cadence circuit design toolbox (2019). The proposed circuit solutions were fabricated with 180-nm CMOS technology and published at IEEE MWSCAS 2020 conference. As the last contribution, the in vitro experiments with the proposed device, including the custom chip and 3D-printed housing, were performed, and the electrical and optical results were submitted to the IEEE Journal of Solid-State Circuits (JSSC 2022)