Monitoring waterbirds have several benefits, including analyzing the number of endangered species, giving a reliable indication of public health, etc. Monitoring waterbirds in their habitat is a challenging task since the location is distant, and the collection of monitoring data requires large bandwidth. A promising technology to tackle these challenges is thought to be Wireless Multimedia Sensor Networks (WMSN). These networks are composed of small energy-constrained IoT devices that communicate together to collect data or monitor a given location. Performances in such networks are impacted by not only upper-layer protocols (transmission, routing, application layer) but also Medium Access Control (MAC) Layer. Therefore, improvement in this layer can increase the performance considerably. Traditional contention-based MAC modes like CSMA have large energy expenditure even though they have a good network performance profile. Energy-constrained devices cannot have a long lifespan with this type of MAC layer technology. Therefore, the IEEE 802.15.4e amendment proposed TSCH MAC mode which takes advantage of time-slotted access and channel hopping techniques. IETF integrated TSCH protocol into IPv6-based wireless sensor networks and standardized it as 6TiSCH which is a unique protocol stack for Low-Power and Lossy Networks (LLN). WMSN applications (e.g. Waterbirds Monitoring Application) generates heterogeneous traffic. Heterogeneous traffic can be defined as a mixture of different traffic types (light: temperature, humidity, etc. and heavy: audio, picture, video, etc.). TSCH-based WMSNs are considered a fit for this kind of traffic since they provide better performance and low power usage.  Yet, the 6TiSCH Working Group left open the scheduling of TSCH communication for industries to make TSCH more easily adaptable to any kind of application. Until now, there have been a huge number of scheduling algorithms from industries and academia. Each scheduling algorithm has a different objective that maximizes the network performance of a specific application. This thesis work studies the most recent state-of-the-art scheduling algorithms (protocols) and compares them in a unique simulation environment with heterogeneous traffic to find out which protocol performs well while maintaining low energy consumption. Particularly, this work studies a new approach in TSCH scheduling which is Reinforcement Learning based scheduling. We implemented one of the state-of-the-art RL-based schedulers in Contiki-NG and included it in our comparison of TSCH schedulers. The experiment results showed that the RL-based scheduler implemented in this work demonstrated better performance in PDR and latency compared to other scheduling protocols. However, it presented high energy usage. On the other hand, Orchestra performed well while keeping the energy expenditure of nodes at a low level.

The purpose of this study was to explore and describe the experiences of Recognition of Prior Learning (RPL) nursing candidates related to the four-year comprehensive nursing training programme at a Nursing Education Institution in Gauteng. To this end an exploratory descriptive qualitative research design was undertaken. The research sample comprised of 13 purposefully selected participants. Face-to-face individual interviews, using open-ended questions (Grand tour), were used to collect data, which was analysed using Tesch’s approach. Findings from the study highlighted the challenges faced by nursing RPL candidates as adult students. These included challenges related to their theoretical learning as well as their clinical facility experiences. Based on the study results, recommendations were formulated in assisting them to successfully and timeously complete their nursing programme / Health Studies / M.A. (Nursing Science)

The purpose of this study was to explore and describe the experiences of Recognition of Prior Learning (RPL) nursing candidates related to the four-year comprehensive nursing training programme at a Nursing Education Institution in Gauteng. To this end an exploratory descriptive qualitative research design was undertaken. The research sample comprised of 13 purposefully selected participants. Face-to-face individual interviews, using open-ended questions (Grand tour), were used to collect data, which was analysed using Tesch’s approach. Findings from the study highlighted the challenges faced by nursing RPL candidates as adult students. These included challenges related to their theoretical learning as well as their clinical facility experiences. Based on the study results, recommendations were formulated in assisting them to successfully and timeously complete their nursing programme / Health Studies / M.A. (Nursing Science)

L'objectif de la thèse est d'étudier la variation temporelle de la qualité des liens dans les réseaux de capteurs sans fil à grande échelle, de concevoir des estimateurs permettant la différenciation, à court terme et long terme, entre liens de qualité hétérogène. Tout d'abord, nous étudions les caractéristiques de deux paramètres de la couche physique: RSSI (l'indicateur de puissance du signal reçu) et LQI (l'indicateur de la qualité de liaison) sur SensLab, une plateforme expérimentale de réseau de capteurs à grande échelle situé à l'intérieur de bâtiments. Nous observons que le RSSI et le LQI permettent de discriminer des liens de différentes qualités. Ensuite, pour obtenir un estimateur de PRR, nous avons approximé le diagramme de dispersion de la moyenne et de l'écart-type du LQI et RSSI par une fonction Fermi-Dirac. La fonction nous permet de trouver le PRR à partir d'un niveau donné de LQI. Nous avons évalué l'estimateur en calculant le PRR sur des fenêtres de tailles variables et en le comparant aux valeurs obtenues avec l'estimateur. Par ailleurs, nous montrons en utilisant le modèle de Gilbert-Elliot (chaîne de Markov à deux états) que la corrélation des pertes de paquets dépend de la catégorie de lien. Le modèle permet de distinguer avec précision les différentes qualités des liens, en se basant sur les probabilités de transition dérivées de la moyenne et de l'écart-type du LQI. Enfin, nous proposons un modèle de routage basé sur la qualité de lien déduite de la fonction de Fermi-Dirac approximant le PRR et du modèle Markov Gilbert-Elliot à deux états. Notre modèle est capable de distinguer avec précision les différentes catégories de liens ainsi que les liens fortement variables. / The goal of the thesis is to investigate the issues related to the temporal link quality variation in large scale WSN environments, to design energy efficient link quality estimators able to distinguish among links with different quality on a short and a long term. First, we investigate the characteristics of two physical layer metrics: RSSI (Received Signal Strength Indication) and LQI (Link Quality Indication) on SensLAB, an indoor large scale wireless sensor network testbed. We observe that RSSI and LQI have distinct values that can discriminate the quality of links. Second, to obtain an estimator of PRR, we have fitted a Fermi-Dirac function to the scatter diagram of the average and standard variation of LQI and RSSI. The function enables us to find PRR for a given level of LQI. We evaluate the estimator by computing PRR over a varying size window of transmissions and comparing with the estimator. Furthermore, we show using the Gilbert-Elliot two-state Markov model that the correlation of packet losses and successful receptions depend on the link category. The model allows to accurately distinguish among strongly varying intermediate links based on transition probabilities derived from the average and the standard variation of LQI. Finally, we propose a link quality routing model driven from the F-D fitting functions and the Markov model able to discriminate accurately link categories as well as high variable links.

During the last decades Recognition of Prior Learning (RPL) has become a more frequently used method to recognise adult’s prior learning. This thesis analyses a process of RPL in health care, where health care assistants are assessed against subjects in the upper-secondary health care program. Prior research on RPL is to a high degree non-theoretical and focus is primarily on policy level research. This thesis adds to the field by progressing a critical social theory perspective on RPL. In the thesis the RPL process is analysed through Jürgen Habermas’ theory of communicative action and Axel Honneth’s Recognition theory. General questions posed are: What are the power issues in the RPL process? What implications does the tension between the lifeworld of work and the system of education have? What consequences does mutual understanding and communication have for the outcome of the RPL process? What part does recognition play for the participants? The results disclose the power relations that emerge in the relationship between participants and teachers. A caring ideology is developed and problematized. Further, the importance of mutual understanding between participant and teachers in the assessment of prior learning is discussed focusing on the consequences a lack of mutual understanding could have for the outcome in such assessments. On a macro level the analysis demonstrates the tension between the participants prior learning and the educational systems demand for formalising prior learning. In addition, analyses of a more developmental character that intends to show the potential for critical learning, change and recognition are progressed. The results suggest that communicative action can be used to develop RPL into processes focusing on critical learning and change. Recognition of traits and abilities could also enhance individual’s positive relations with the self. Such recognition could develop self-confidence and thus RPL could encourage learning and cultivate continuing self-realisation through work. / Validering har under de senaste decennierna blivit en alltmer använd metod för att erkänna vuxnas tidigare lärande. Denna avhandling analyserar en valideringsprocess inom omvårdnadssektorn för vårdbiträden med mångårig erfarenhet. Vårdbiträdena valideras mot ämnen inom omvårdnadsprogrammets karaktärsämnen. Tidigare forskning om validering är i hög grad icke-teoretisk och mycket fokus har legat på policynivå. Denna avhandling bidrar till forskningsfältet genom att problematisera validering utifrån ett kritiskt samhällsteoretiskt perspektiv. I avhandlingen analyseras valideringsprocessen utifrån Jürgen Habermas teori om det kommunikativa handlandet och Axel Honneths erkännandeteori. Exempel på mer generella frågor som ställs är: Vilka är maktfaktorerna i valideringsprocessen? Är handlingarna i processen koordinerade mot gemensam förståelse? Hur ser förhållandet mellan system och livsvärld ut? Vilken roll spelar erkännandet i validering för deltagarna? Resultatet synliggör de maktförhållanden som uppstår mellan deltagare och lärare i bedömningsprocessen. En omvårdande ideologi lyfts fram och problematiseras. Därtill diskuteras betydelsen av gemensam förståelse mellan deltagare och lärare vid bedömning, samt vilka konsekvenser brist på gemensam förståelse kan få. På ett makroplan åskådliggör analysen spänningen mellan deltagarnas erfarenheter och utbildningssystemets krav på formalisering. Vidare genomförs mer utvecklingsfokuserade analyser som vill visa på möjligheterna för kritiskt lärande och förändring i validering. Resultatet demonstrerar också, bland annat, betydelsen av att bli erkänd för sina förmågor och hur detta kan utveckla individens självuppskattning och främja lärande. I studien föreslås det att kommunikativt handlande kan utgöra en norm för hur validering kan utvecklas mot mer kritiskt lärande och positiv förändring. Men också att erkännande av tidigare förmågor kan gynna individens positiva relation till sig själv, hur detta främjar lärande, självuppskattning och hur validering därmed kan utgöra en grund för ett vidare självförverkligande genom arbete.

Abstract Wireless sensors play a bigger and bigger role in our everyday life and they have become a part of our life in homes, vehicles, traffic, food production and healthcare, monitoring and controlling our activities. Low-cost and resource-efficient solutions are an essential part of this development. The aim of the study was to develop solutions, which improve the energy efficiency of wireless sensor networks yet still fulfil the requirements of monitoring applications. In the study, five new solutions were developed to save energy in wireless sensor networks and all the solutions were studied and verified with test bed implementations. The developed solutions are: 1. Energy-efficient medium access control (MAC), namely revive MAC (R-MAC) for duty-cycling networks with a long sampling interval (many minutes) 2. Wake-up radio solution for on-demand sampling networks, which uses the main radio as the wake-up transmitter 3. Energy-efficient internet of things (IoT) routing solution for wake-up routing with a routing protocol for low-Power and lossy networks (RPL) 4. Energy-efficient IoT compression solution: robust header compression (ROHC) compression with constrained application protocol (CoAP) 5. Data analysis solution based on an energy-efficient sensor node, where filter clogging is forecast from analysis of the vibration data at the node. All the developed solutions were promising and can be utilized in many domain areas. The solutions can be considered as proofs of concept, which need to be developed further for use in final products. / Tiivistelmä Langattomat sensoreilla on yhä suurempi osuus jokapäiväisessä arjessa, jossa langattomat sensorit ovat tulleet osaksi kodin, autojen, ruuantuotannon sekä terveyden valvonta- ja seurantajärjestelmiä. Oleellisena osana tätä kehitystä ovat sekä edulliset että energia- ja resurssitehokkaat ratkaisut. Työn päämääränä oli kehittää ratkaisuja, jotka parantavat langattoman sensoriverkon energia tehokkuutta niin, että edelleen täytetään monitorointi sovellutusten asettamat vaatimukset. Työssä kehitettiin viisi uutta ratkaisua säästää energiaa langattomissa sensoriverkoissa ja kaikki ratkaisut tutkittiin ja varmennetiin työssä tehdyillä testi alustoilla. Kehitetyt ratkaisut ovat: 1. Energiatehokas alempi siirtoyhteyskerroksen protokolla (medium access control, MAC), nimittäin heräävä MAC (Revive MAC, R-MAC) jaksoittain toimiville (duty-cycling) verkoille, joissa on pitkät mittausvälit (useita minuutteja). 2. Heräteradioratkaisu (wake-up) pyynnöstä toimiville (on-demand) verkoille, joissa pääradiota käytetään heräte signaalin lähettämiseen. 3. Energiatehokas esineiden internetin (Internet of Things, IoT) reititysratkaisu herätereititykseen käyttäen matalatehoisille ja häviöllisille verkoille suunniteltua reititysprotokollaa (Routing protocol for low-Power and Lossy networks, RPL). 4. Energiatehokas IoT-pakkausratkaisu: varmatoiminen otsakkeen pakkausprotokolla (Robust Header Compression, ROHC) yhdessä rajoitettujen sovellusten protokollan (Constrained Application Protocol, CoAP) kanssa. 5. Energiatehokas sensorilaite perusteinen data prosessointi ratkaisu suodattimen tukkeutumisen ennustamiseen värähtelymittauksia käyttäen. Kaikki kehitetyt ratkaisut olivat lupaavia ja niitä voidaan käyttää useilla sovellutusalueilla. Ratkaisut ovat soveltuvuusselvityksiä (proof of concept), joita pitää kehittää edelleen loppu tuotteiden käyttöön.

[ES] La industria se encuentra inmersa de pleno en la cuarta revolución industrial, y es gracias a la capacidad de digitalización y de procesamiento de grandes cantidades de datos, que se consigue mejorar y optimizar el rendimiento de los sistemas industriales actuales. Son muchos los paradigmas y conceptos que están dando forma a lo que se conoce como Industria 4.0, y uno de ellos ha sido el Internet de las Cosas (IoT: Internet of Things) o más concretamente el Internet Industrial de las Cosas (IIoT: Industrial Internet of Things), como se ha llamado al subconjunto con determinados requisitos orientados al sector industrial. Las redes de sensores inalámbricos (WSN: Wireless Sensor Networks) son tecnologías habilitadoras para estos sistemas IoT, ya que gracias a su fácil escalabilidad ofrecen gran capacidad de sensorización con un coste energético reducido. En el ámbito industrial, estas redes de sensores deben cumplir con requisitos estrictos de fiabilidad, y su aceptación está siendo lenta debido a que su robustez y facilidad de configuración no han podido rivalizar con las tecnologías clásicas. Con el desarrollo de esta tesis, se pretende hacer frente a determinados aspectos de mejora de las redes industriales de sensores inalámbricos. Para ello, se diseñan nuevos mecanismos para la sincronización, evaluando metodologías alternativas de enrutamiento y proponiendo modelos analíticos que permitan caracterizar fielmente el proceso de despliegue de estas redes, con el objetivo de cubrir aquellas lagunas que dejan los estándares y protocolos bajo estudio. Los mecanismos propuestos por el estándar IEEE 802.15.4e, en concreto el método de acceso al medio mediante TSCH (Time-Slotted Channel Hopping), presentan las bases sobre las que construir una red WSN fiable y robusta, y mediante los desarrollos propuestos en esta tesis se facilita su implantación en sistemas de Industria 4.0. / [CA] La indústria es troba de ple en la quarta revolució industrial, i és gràcies a la capacitat de digitalització i de processament de grans quantitats de dades, que s'aconsegueix millorar i optimitzar el rendiment dels sistemes industrials actuals. Són moltes els paradigmes i conceptes que estan donant forma al que es coneix com a Indústria 4.0, i una d'elles ha sigut la Internet de les Coses (IoT: Internet of Things) o més concretament la Internet Industrial de les Coses (IIoT: Industrial Internet of Things), com s'ha anomenat al subconjunt amb determinats requisits orientats al sector industrial. Les xarxes de sensors sense fils (WSN: Wireless Sensor Networks) són tecnologies habilitadores per a sistemes IoT, ja que gràcies a la seua fàcil escalabilitat ofereixen gran capacitat de digitalització amb un cost energètic reduït. En l'àmbit industrial, aquestes xarxes de sensors han de complir amb requisits estrictes, i la seua acceptació està sent lenta a causa de factors que fan que aquests sistemes no substituïsquen a les tecnologies clàssiques. Amb el desenvolupament d'aquesta tesi, es pretén fer front a determinats aspectes de millora de les xarxes industrials de sensors sense fils. Per a això, es dissenyen nous mecanismes per a la sincronització, avaluant metodologies alternatives d'encaminament i proposant models analítics que permeten caracteritzar fidelment el procés de desplegament d'aquestes xarxes, amb l'objectiu de cobrir aquelles llacunes que deixa l'estàndard. Els mecanismes proposats per l'estàndard IEEE 802.15.4, en concret el mètode d'accés al mitjà TSCH, presenten les bases sobre les quals construir una xarxa WSN fiable i robusta, i mitjançant els desenvolupaments proposats en aquesta tesi es facilita la seua implantació en sistemes d'Indústria 4.0. / [EN] The industry is fully engaged in the fourth industrial revolution. Due to digital transformation and the processing of large amounts of data, it is possible to improve the value chain and provide a real-time optimization for the current industrial systems. There are many paradigms and concepts that that fall under the umbrella of Industry 4.0, and one of them is the Internet of Things (IoT) or more specifically the Industrial Internet of Things (IIoT), as the subset with certain industry-oriented requirements is known. Wireless Sensor Networks (WSN) are an enabling technology for IoT systems, since its easy scalability offers a great sensorization capacity with a reduced energy cost. In the industrial field, these sensor networks must meet strict reliability requirements, so growth in the industrial market is slow as these systems fail to replace legacy technologies. This thesis addresses different aspects of improving industrial wireless sensor networks. To that end, new mechanisms for synchronization have been designed, evaluating alternative routing methodologies and proposing analytical models that allow a comprehensive characterization of the deployment process of these networks, aiming of covering those gaps left by the standard. The mechanisms proposed by the IEEE 802.15.4 standard, specifically the medium access control method Time-Slotted Channel Hopping (TSCH), present the bases to deploy a reliable and robust WSN network, and through the developments proposed in the thesis, it is possible smooth the way for its implementation in Industry 4.0 systems. / Vera Pérez, J. (2021). Diseño y evaluación de mecanismos de optimización en redes de sensores inalámbricas industriales [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/179700 / TESIS

No description available.

Thesis (MPhil)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The purpose of this study was to investigate the impact of the NQF on higher education institutions focussing specifically on access, teaching and learning. The study aimed to answer the following research questions: What was the impact of the NQF on increasing access to higher education? In particular how did the RPL process facilitate access into the University of Pretoria? Secondly, how did the NQF influence the processes of teaching and learning at this particular institution? And finally, why did the NQF have differential impacts on different faculties within the same higher education institution? To gain the end-users’ perspective, a case study of the University of Pretoria was conducted. Data was gathered using interviews with ten senior members of staff at the university working in nine different departments, and student records indicating admissions through RPL into the University of Pretoria as well as relevant institutional documents. The findings suggest that the impact of the NQF on access, teaching and learning differed across departments, resulting in a partial implementation of the policy. This was facilitated by factors inherent in the policy itself and factors inherent to the institution. The influence of external factors such as professional bodies on teaching and learning practices of end-users at the University of Pretoria posed a major challenge against NQF implementation. The motivations leading to NQF implementation are not directly linked to the NQF policy per se, although they resulted in portraying the extent of change to access, teaching and learning along a continuum that distinguished between departments that ‘blindly complied’, that selectively adapted and those that strategically avoided implementation of the policy. Indications for further research are that a wider look at the impact of the NQF on access, teaching and learning in higher education is less revealing than a more focussed investigation. Future research should zoom-in on individual departments within higher education institutions to reveal the deeper and more nuanced impact of the NQF. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die impak van die NKR (NQF) op veral toegang, onderrig en leer in hoër onderwysinstellings te ondersoek. Die studie poog om die volgende navorsingsvrae te beantwoord: Watter impak het die NKR op toenemende toegang tot hoër onderwys? Hoe fasiliteer die EVL-proses ("RPL process") toegang tot die Universiteit van Pretoria? Hoe beïnvloed die NKR die onderrig- en leerproses aan hierdie spesifieke instelling? Ten slotte, waarom het die NKR 'n differensiële invloed op verskillende fakulteite binne dieselfde hoër onderwysinstelling? Ten einde die uiteindelike gebruiker se perspektief te bepaal, is 'n gevallestudie aan die Universiteit van Pretoria uitgevoer. Data is ingesamel uit onderhoude met tien senior personeellede wat in nege verskillende departemente werk, studenterekords aangaande toelating tot die Universiteit van Pretoria deur EVL, en ook relevante institutêre dokumente. Die bevindinge impliseer dat die impak van die NKR op toegang, onderrig en leer van departement tot departement verskil en dat dit lei tot 'n gedeeltelike implementering van die beleid. Dié verskil is aangehelp deur faktore wat inherent is aan die beleid, maar ook faktore inherent aan die instelling. Die invloed wat eksterne faktore soos professionele liggame op die onderrig- en leerpraktyke van finale gebruikers aan die Universiteit van Pretoria het, is 'n groot struikelblok vir die implementering van die NKR. Motiverings wat lei tot die implementering van die NKR is nie noodwendig aan die NKR-beleid gekoppel nie, alhoewel dit daartoe gelei het dat die mate van verandering in toegang, onderrig en leer op 'n kontinuum aangedui is. Hierdie kontinuum onderskei tussen departemente wat die beleid "blindelings navolg", ander wat dit selektief aanpas en nog ander wat die implementering van die beleid strategies vermy. Aanduidings vir verdere navorsing is dat 'n breë ondersoek van die NKR se impak op toegang, onderrig en leer in hoër onderwys minder beduidend is as 'n meer spesifieke ondersoek. Toekomstige navorsing behoort te fokus op individuele departemente binne hoër onderwysinstellings ten einde 'n indringender en meer genuanseerde impak van die NKR te bepaal.

Networked control over wireless networks is of growing importance in many application domains such as industrial control, building automation and transportation systems. Wide deployment however, requires systematic design tools to enable efficient resource usage while guaranteeing close-loop control performance. The control system may be greatly affected by the inherent imperfections and limitations of the wireless medium and malfunction of system components. In this thesis, we make five important contributions that address these issues.  In the first contribution, we consider event- and self-triggered control and investigate how to efficiently tune and execute these paradigms for appropriate control performance. Communication strategies for aperiodic control are devised, where we jointly address the selection of medium-access control and scheduling policies. Experimental results show that the best trade-off is obtained by a hybrid scheme, combining event- and self-triggered control together with contention-based and contention-free medium access control. The second contribution proposes an event-based method to select between fast and slow periodic sampling rates. The approach is based on linear quadratic control and the event condition is a quadratic function of the system state. Numerical and experimental results show that this hybrid controller is able to reduce the average sampling rate in comparison to a traditional periodic controller, while achieving the same closed-loop control performance. In the third contribution, we develop compensation methods for out-of-order communications and time-varying delays using a game-theoretic minimax control framework. We devise a linear temporal coding strategy where the sensor combines the current and previous measurements into a single packet to be transmitted. An experimental evaluation is performed in a multi-hop networked control scenario with a routing layer vulnerability exploited by a malicious application. The experimental and numerical results show the advantages of the proposed compensation schemes. The fourth contribution proposes a distributed reconfiguration method for sensor and actuator networks. We consider systems where sensors and actuators cooperate to recover from faults. Reconfiguration is performed to achieve model-matching, while minimizing the steady-state estimation error covariance and a linear quadratic control cost. The reconfiguration scheme is implemented in a room heating testbed, and experimental results demonstrate the method's ability to automatically reconfigure the faulty system in a distributed and fast manner. The final contribution is a co-simulator, which combines the control system simulator Simulink with the wireless network simulator COOJA. The co-simulator integrates physical plant dynamics with realistic wireless network models and the actual embedded software running on the networked devices. Hence, it allows for the validation of the complete wireless networked control system, including the study of the interactions between software and hardware components. / <p>QC 20140929</p>