MCom / Department of Business Management / See the attached abstract below

DEd (Educational Management) / Department of Educational Management / The study investigated the effectiveness of information collected through the SASAMS form in the Department of Basic Education in John Taolo Gaetsewe District in the Northern Cape. The research adopted the two research paradigms, namely, positivism and interpretivism. The research is situated within theories of leadership and organizational effectiveness. The mixed methods research design was used in this study. The study used the survey, interviews, documentary analysis and observation as research methods. The population comprised 171 schools in John Taolo Gaetsewe District. A simple random sampling procedure was employed to get a sample of 30 schools comprised 240 teachers, 3 teacher union representatives and 5 school governing body (SGB) members. Purposive sampling technique was also employed to choose 6 school principals and two EMIS Unit personnel. Qualitative data was generated through interviews, observation and documentary analysis. A survey was administered to obtain quantitative data. Statistical Package for Social Sciences (SPSS) version 24 was used for statistical information. Grounded theory was also employed, and it further provided a descriptive framework which assists in the understanding of a phenomenon that was being investigated. It was established that there were big disparities between enrolment figures declared and the actual ones that prevailed in schools. The study recommends that Circuit District Offices should constantly check and monitor the existence and maintenance of data source documents in schools in order that correct enrolment figures are maintained in schools at all times to enable effective planning processes. The SA-SAMS form should also incorporate a mechanism for detecting ‘ghost personnel’ and ‘ghost learners.’ The study further recommends the linking of HRMS and SA-SAMS tools to play complimentary roles so as to curb malpractices bedeviling the DBE. Additionally, the DBE should consider revising the policy where schools are allowed to factor in a 10% enrolment increase as it creates a good foundation for data falsification by unscrupulous officials. / NRF

This study has been conducted with Sirius International as a case company. The investigation has revolved around the weaknesses Sirius, along with the authors, have identified concerning the international collaboration and communication. It was later shown that these problems were based on a low sense of unity in the organization as a result of the lack of knowledge sharing, knowledge management, and spread of organization related information. It was decided to evaluate whether a corporate social network (CSN) could assist in these problems and if so, decide what system would be the most appropriate in regards to the internal needs and requirements at Sirius. The major challenges brought on with an implementation of a CSN, and how to face these, were investigated as a part of the evaluation whether a CSN would be appropriate for Sirius or not. The study showed that a CSN was an appropriate choice for Sirius in order to improve the international communication, collaboration, and unity. The most suitable choice was determined to be Yammer, as it best suited the internal requirements and needs. Along with these results, the largest challenge with an implementation and future use of the system was user acceptance and overall usage of the system. If the CSN is not used, none of the visions, goals, or purposes will be fulfilled. / Denna studie har gjorts med Sirius International som case-företag. Undersökningen har kretsat kring svagheterna som Sirius, tillsammans med författarna har identifierat kring det internationella samarbetet och kommunikationen. Det visade sig senare att dessa problem var grundade i en låg känsla av samhörighet i organisationen och att detta var ett resultat av den låga nivån av kunskapsspridning, kunskapshantering och spridning av organisationsrelaterad information. Beslutet togs att undersöka huruvida ett företags-baserat socialt nätverk kunde hjälpa vid dessa problem och, om fallet var sådant, komma fram till vilket socialt nätverk som skulle vara mest lämpat vid avseende på de interna behoven och kraven från Sirius. Vid undersökningen om huruvida ett socialt nätverk var lämpligt för Sirius gjordes också en undersökning för att identifiera de största utmaningarna med en implementation av ett socialt nätverk och hur dessa skall bemötas och övervinnas. Studien visade att ett företagsbaserat socialt nätverk var ett lämpligt val för att överkomma problemen i Sirius och förbättra den internationella kommunikationen, samarbetet och samhörigheten. Det lämpligaste sociala nätverket för Sirius blev Yammer som bäst täckte de interna behoven och kraven hos Sirius. Tillsammans med dessa resultat visade undersökningen att den största utmaningen med en implementation och framtida nyttjande av systemet var användaracceptans och generell användning av systemet. Om ett socialt nätverk inte används så kan inga av visionerna, målen eller syftena med systemet infrias.

Abstracts in English and Xhosa / Given the need for prompt responses to today’s dynamic market, maintenance and maintenance management functions are becoming increasingly fundamental for industrial companies. Reduction of waste and bottlenecks, particularly the reduction of overproduction and work in process, accentuates the impact of malfunctions or failures of equipment on production. As such, it has become ever more urgent for proactive world-class maintenance to turn to computer-based support for efficacious management. To successfully manage activities such as the scheduling of activities, the planning of preventive maintenance actions, the analysis of data (to reduce the occurrence of malfunction and failures), and augment the absolute performance of the maintenance function, industrial companies implement information systems enabled by computerised maintenance management systems (CMMS) to deliver timely and accurate information. However, while various CMMS are available on the market, not all meet the exactitudes of each industrial company. The overall objective of this thesis is threefold: to explore major barriers and obstacles that have a negative impact on implementing CMMS; to identify the most common critical success factors (CSFs) that have a positive impact on implementing CMMS; and to develop an optimised CMMS model suitable to the context of Ethiopian manufacturing industries. To achieve this, an exploratory descriptive research design was employed, utilising both quantitative and qualitative data-gathering techniques, including structured interviews and questionnaires. Both qualitative and quantitative findings Suggest that the most important CSFs for CMMS implementation were work planning and scheduling and work identification and responsibilities, while the Ethiopian manufacturing firms lagged behind in the case of information technology and appraisal. Overall, key isues in maintenance management range from several maintenance techniques, information systems, scheduling, and optimisation models. This thesis is projected to be a useful source of information for both maintenance managers and stakeholders in CMMS decision making. It also creates opportunities for future research in this area of study. / Ngenxa yesidingo seempendulo ezikhawulezileyo kwimarike yanamhlanje eguqukayo, ukulondoloza kunye nololondolozo lwemisebenzi yolowulo ziya zisanda ngokubaluleka kwiinkampani zoshishino. Ukuncitshiswa kwenkcitho kunye nokuxinana kwindawo eziphezulu , ngakumbi ukucuthwa kwemveliso egqithisileyo kunye nokusebenza kwinkqubo, kunyusa ifuthe lokungasebenzi kakuhle okanye ukusilela kwezixhobo kwimveliso. Kananjalo, kuye kwangxamiseka nangakumbi kulondolozo lwenqanaba lehlabathi ukuba liphendukele kwinkxaso esekwe kwikhompyutha ukwenzela ulawulo olusebenzayo. Ukulawula ngempumelelo imisebenzi efana nokucwangciswa kwemisebenzi, ukucwangciswa kwezenzo zolondolozo zokukhuselo, ucalulo lwedatha (ukunciphisa ukwenzeka kokungasebenzi kakuhle kunye nokusilela), kunye nokwandisa ukusebenza ngokupheleleyo komsebenzi wolondolozo, iinkampani zamashishini zisebenzisa iinkqubo zolwazi ezenziwa ziinkqubo zolawulo lokulondoloza ngekhompyutha (i-CMMS) ukuhambisa ulwazi oluchanekileyo kwangexesha. Nangona kunjalo, ngelixa ii-CMMS ezahlukeneyo zifumaneka kwimarike, ayizizo zonke ezihlangabezana ngqo nemilinganiselo yenkampani nganye yemizimveliso. Eyona njongo yale ngcingane ebhaliweyo engqinelwa ziingxoxo, ithisisi ihlulwe kathathu: ukuphonononga imiqobo engundoqo kunye nezithintelo ezinefuthe elibi ekuphumezeni iiCMMS; Ukuchonga ezona zinto zibalulekileyo zempumelelo (CSFs) ezinefuthe elihle ekuphumezeni iCMMS; kunye nokuvelisa imodeli ye-CMMS elungele imeko yemizimveliso yase-Ethiopia. Ukufezekisa oku, uyilo lophando oluchazayo lwasetyenziswa, kusetyenziswa ubuchule bokuqokelela idatha eninzi kunye nesemgangathweni, kubandakanya udliwanondlebe olulungiselelweyo kunye nephepha lemibuzo.Zozibini iziphumo ezedatha esengangathweni kunye nedatha ngokobungakanani zibonisa ukuba ezona CSFs zibalulekileyo ekuphunyezweni kweCMMS yayikukucwangciswa komsebenzi nokucwangciswa nokwenza uludwe lweenkqubo kunye nokuchongwa komsebenzi kunye noxanduva, ngelixa iifemu zemveliso zase-Ethiopia zisasele ngasemva kwimeko yolwazi lwetekhnoloji kunye novavanyo. Kukonke, imiba ephambili kulawulo lolondolozo isukela kwiindlela ezahlukeneyo zobuchule zolondolozo, kwiinkqubo zolwazi, kuludwe lokwenziwa kweenkqubo zolwazi, kunye neemodeli ezigqibeleleyo. Le thisisi kuqikelelwa ukuba ingumthombo wolwazi oluluncedo kubo bobabini abaphathi bezolondolozo kunye nabachaphazelekayo ekuthathweni kwezigqibo kwiCMMS. Ikwadala amathuba ophando lwexesha elizayo kulo mmandla wokufunda. / Business Management / DBL (Business Leadership)

Vital societal functions are upheld by public infrastructure. For some time, normative theories describing asset management have disseminated in research and in business. Public infrastructure companies are increasingly required to adhere to management standards under regulatory pressure, however, the research area is in need of more empirical contributions on which challenges companies face when implementing management systems standards in their organization. For asset management systems and the ISO 55000 series in particular, the empirical data is lacking. This thesis addresses the challenges public utility companies face when implementing asset management principles. A qualitative case study was conducted during a five-month period at Sweden's largest water utility company, Stockholm Vatten och Avfall AB (SVOA). Fourteen interviews were conducted and compared with company documents to provide triangulation. The findings suggest that the main challenges a public utility company has to overcome to implement an asset management model are: 1) Lack of strategic and long-term planning responsibility. 2) Unclear division of asset responsibilities. 3) Lack of top management commitment towards asset management systems. 4) No standardized risk management. 5) Lack of information sharing between departments. The implications of this study are twofold: In a practical sense the thesis argues for top management of public infrastructure firms to commit to principles of asset management theory, provide a clear division of asset responsibility, introduce systematic risk management principles and policies, as well as promote cross-divisional exchanges of experiences. Academically, this investigation contributes to the literature by providing a better understanding of the ISO 55000 series, and the implementation process of standards similar to it, in the context of companies managed by the public sector. / Kritiska samhällsfunktioner möjliggörs av offentlig infrastruktur. Sen ett antal år tillbaka finns flertalet normativa teorier publicerade som beskriver hur tillgångshantering (asset management) ska gå till. Under krav från lagstiftning och tillsynsmyndigheter måste offentliga verksamheter i allt högre grad införa standardiserande arbetssätt. Det finns en brist på forskning kring utmaningarna att bygga upp och införa ledningssystem i verksamheten. Särskilt ledningssystem för tillgångshantering som till exempel ISO 55000 saknar empiriska data. Detta examensarbete behandlar de utmaningar offentliga infrastrukturbolag står inför för att implementera tillgångshanteringsprinciper. En kvalitativ fallstudie gjordes över fem månader på Sverige största leverantör av vattentjänster, Stockholm Vatten och Avfall AB (SVOA). Totalt fjorton intervjuer gjordes och jämfördes mot interna företagsdokument för att uppnå triangulering. Resultaten pekar på att de största utmaningarna ett offentligt infrastrukturbolag måste övervinna är: 1) Brist på strategisk och långtidsplanering. 2) Otydlig fördelning av tillgångsansvar. 3) Brist på ledningsengagemang för tillgångshanteringssystem. 4) Avsaknad av standardiserad riskhantering. 5) Brist på informationsutbyte. Konsekvenserna av examensarbetet är tvåfaldig: På ett praktiskt plan argumenterar examensarbetet för att ledningen av offentliga infrastrukturbolag bör förpliktiga sig åt tillgångshanteringsprinciper. De bör även införa en tydlig uppdelning av tillgångsansvar, introducera standardiserade riskhanteringsmodeller och policy, samt bidra till tvärfunktionella erfarenhetsutbyten. På ett akademiskt plan bidrar examensarbetet till att utöka förståelsen för ISO 55000 standarden och implementeringsprocessen för liknande standarder i kontexten av offentligt styrda företag.

<p>An emerging technology in the field of transient thermal management is thermal energy storage, or TES, which enables temporary, on-demand heat rejection via storage as latent heat in a phase-change material.  Latent TES devices have enabled advances in many thermal management applications, including peak load shifting for reducing energy demand and cost of HVAC systems and providing supplemental heat rejection in transient thermal management systems.  However, the design of a transient thermal management system with integrated storage comprises many challenges which are yet to be solved.  For example, design approaches and performance metrics for determining the optimal dimensions of the TES device have only recently been studied.  Another area of active research is estimation of the internal temperature state of the device, which can be difficult to directly measure given the transient nature of the thermal storage process.  Furthermore, in contrast to the three main functions of a thermal-fluid system--heat addition, thermal transport, and heat rejection--thermal storage introduces the need for active, real-time control and automated decision making for managing the operation of the thermal storage device. </p> <p>In this thesis, I present the design process for integrating thermal energy storage into a single-phase thermal management system for rejecting transient heat loads, including design of the TES device, state estimation and control algorithm design, and validation in both simulation and experimental environments. Leveraging a reduced-order finite volume simulation model of a plate-fin TES device, I develop a design approach which involves a transient simulation-based design optimization to determine the required geometric dimensions of the device to meet transient performance objectives while maximizing power density.  The optimized TES device is integrated into a single-phase thermal-fluid testbed for experimental testing.  Using the finite volume model and feedback from thermocouples embedded in the device, I design and experimentally validate a state estimator based on the state-dependent Riccati equation approach for determining the internal temperature distribution to a high degree of accuracy.  Real-time knowledge of the internal temperature state is critical for making control decisions; to manage the operation of the TES device in the context of a transient thermal management system, I design and test, both in simulation and experimentally, a logic-based control strategy that uses fluid temperature measurements and estimates of the TES state to make real-time control decisions to meet critical thermal management objectives. Together, these advances demonstrate the potential of thermal energy storage technology as a component of thermal management systems and the feasibility of logic-based control strategies for real-time control of thermal management objectives.</p>

Many healthcare organisations face repetitive incidents because organisations tend to fail to learn from the past. Learning from incidents (LFI) in healthcare is a process through which healthcare professionals and the organisation as a whole seek to understand adverse events that have taken place. The LFI process consists of five main steps: data acquisition, investigation and analysis, planning interventions, implementing interventions, and evaluations. In order to reduce the reoccurrence of incidents, it is important that LFI processes are improved. As a prerequisite, it is necessary to gain insight into the steps of the LFI process to identify hindrances (bottlenecks) and mitigate them. This thesis is a broad comparative study of the LFI processes in Dutch and Swedish healthcare systems. Cross-border comparisons between LFI systems can support mutual learning, and consequently lead to improvements of healthcare organisations’ learning processes. The study consists of an analysis of Swedish and Dutch legislation, national healthcare inspectorates, and hospitals’ learning from incidents processes. Legislation was analysed through a (legal) documentation study. Healthcare inspectorates’ practices in LFI were analysed by a combination of documentation studies, and by conducting interviews with one Dutch inspector, one Swedish inspector, and one Swedish development strategist. For analysis of hospitals’ LFI processes, a questionnaire and interview study with fourteen Dutch and eleven Swedish hospitals were conducted. Analysis of these processes was done at the hand of a number of quality statements developed based on a literature study. The main differences between how the two countries’ learn from incidents are in data acquisition, and investigation and analysis. The Netherlands have various reporting systems, as well as diversity in incident investigation methods. Sweden has more uniformity in these matters. Moreover, Sweden has a national system for sharing lessons learned between hospitals, which can benefit the learning process on a national level. The Netherlands currently does not have such a system. Sweden and the Netherlands have similar strengths and weaknesses in LFI. Both countries have accessible data acquisition systems, and it does not take much time to report incidents. There are however significant disparities between incidents and sentinel events in both countries in the quality of investigations and analyses, planning of interventions and implementation of interventions. The implementation and evaluation phases are also regarded to have the lowest quality, based on analysis of the quality statements. Dutch and Swedish legislation and the supervision of the healthcare inspectorates only cover these last two phases to a limited extent. Requirements with respect to incidents are also only formulated to a limited extent (except data acquisition), which may explain the significant difference of quality when compared to sentinel events. There are resemblances between the scopes of the legal frameworks and inspectorates, and the LFI processes in hospitals. There is therefore reason to believe that hospitals typically do not excel above what is required by legislation or by the healthcare inspectorates. / I många vårdorganisationer upprepar sig incidenter eftersom organisationer tenderar att misslyckas med att lära sig från incidenter. Att lära från incidenter (LFI) inom hälso- och sjukvården är en process genom vilket vårdpersonal och organisationen som helhet försöker förstå incidenter som har ägt rum. LFI-processen består av fem huvudsteg: datainsamling, utredning och analys, planering av åtgärder, implementering av åtgärder, och utvärderingar. För att minska upprepande av incidenter är det viktigt att LFIprocesser förbättras. Det här examensarbetet är en jämförande studie av LFI-processerna i holländska och svenska sjukvårdssystem. Gränsöverskridande jämförelser mellan LFI-system kan stödja ömsesidigt lärande och därmed leda till förbättringar av vårdorganisationernas lärande. Studien består av en analys av svensk och holländsk lagstiftning, nationella inspektioner och sjukhusens lärande från incidensprocesser. Lagstiftningen analyserades genom en (juridisk) dokumentationsstudie. Sjukvårdsinspektionernas praxis i LFI analyserades med en kombination av dokumentationsstudier och genom att göra intervjuer med en holländsk inspektör, en svensk inspektör och en svensk utvecklingsstrateg. För analys av sjukhusens LFI-processer genomfördes en enkätstudie och intervjustudie med 14 holländska och 11 svenska sjukhus. Analysen genomfördes med ett kvalitetsindikatorer som är baserade på en litteraturstudie. De viktigaste skillnaderna mellan hur de två länderna lär sig av incidenter är inom datainsamling och incidentutredning. I Nederländerna används många olika rapporteringssystem och utredningsmetoder för händelser. Sverige har mer enhetlighet i dessa frågor. Dessutom har Sverige ett nationellt system för att dela lärdomar mellan sjukhusen, vilket kan gynna lärningsprocessen på nationell nivå. Nederländerna har för närvarande inget liknande system. Sverige och Nederländerna har liknande styrkor och svagheter i LFI. Båda länderna har tillgängliga datainsamlingssystem och det tar inte mycket tid att rapportera incidenter. Det finns betydliga skillnader mellan incidenter och händelser som har medfört allvarliga vårdskador i båda länderna. Detta gäller kvaliteten på utredningar, planering av åtgärder och implementering av årgärder. Implementerings- och utvärderingsfaserna anses ha lägsta kvalitet, baserat på analys av kvalitetsindikatorerna. Holländsk och svensk lagstiftning och tillsynen av inspektionerna täcker dessa två sista faser endast i begränsad utsträckning. Krav på incidenter formuleras också endast i begränsad omfattning (förutom datainsamling), vilket kan förklara skillnaden i kvalitet jämfört med händelser som har medfört en allvarlig vårdskada. Det finns likheter mellan räckvidden av lagstiftningen och inspektionen, och LFIprocesserna på sjukhus i både länder. Det finns därför anledning att tro att sjukhus vanligtvis inte utmärker sig högre än vad som krävs enligt lagstiftningen eller av hälsooch sjukvårdsinspektionerna.

[pt] O objetivo da dissertação é avaliar a gestão da função metrológica em uma unidade de exploração e produção de óleo e gás de uma grande empresa de energia no Brasil e propor ações de melhoria a partir dos resultados do diagnóstico da referida função. Desde a emissão da Portaria Conjunta n°1 ANP/Inmetro, em junho de 2000, as atividades de exploração e produção de petróleo e gás natural no Brasil passaram por um acelerado processo de reestruturação organizacional e de adequação das instalações de medição para atender ao novo marco regulatório. Nesse contexto, a motivação da pesquisa vincula-se a uma real necessidade de melhoria da gestão da função metrológica em uma unidade de exploração e produção de óleo e gás natural da Petrobras, particularmente no que tange à consolidação da cultura metrológica e ao desenvolvimento de competências associadas a novos requisitos de medição de vazão de óleo e gás natural. A metodologia compreende: (i) pesquisa bibliográfica e documental sobre os temas centrais; (ii) proposição de modelo conceitual para avaliação da gestão da função metrológica; (iii) elaboração e aplicação do instrumento de pesquisa; (iv) estudo de caso da Unidade de Operações de Exploração e Produção da Petrobras no Espírito Santo e de quatro unidades incorporadas ao caso; (v) proposição de ações frente aos desafios e oportunidades reveladas no diagnóstico situacional. Destacam-se como resultados da pesquisa: (i) o modelo conceitual para avaliação da gestão da função metrológica, com foco na medição de vazão de óleo e gás natural; (ii) o diagnóstico da situação atual da gestão da função metrológica na referida Unidade e em quatro unidades incorporadas ao estudo de caso; (iii) mapeamento dos desafios e oportunidades associados à efetiva gestão da função metrológica nas unidades analisadas. Como conclusão, a pesquisa mostra que o modelo conceitual proposto foi adequado para os fins a que se destina, constituindo um importante instrumento de avaliação e retroalimentação para a gestão da função metrológica. Esse modelo poderá ser disseminado em outros contextos organizacionais de exploração e produção de óleo e gás natural. / [en] The objective of this dissertation is two-fold: (i) to assess the management of metrological function of an oil and gas exploration and production unit within a large energy enterprise in Brazil; and (ii) to propose recommendations for its improvement. Since the creation of Portaria Conjunta n 1 ANP/Inmetro, in June 2000, oil and gas exploration and production activities in Brazil have suffered an accelerated process of organizational reengineering and adapted all their measurement installations to attend the new regulatory framework. In this context, the motivation of this research arose from Petrobras’needs to have an assessment tool capable of measuring efficiency and efficacy of its metrological function, incorporating in the analytical framework elements concerning organizational culture and development of competences towards attendance of new metrological requirements. The methodology comprises: (i) bibliographic and documentary research on the central themes of dissertation; (ii) propose of a conceptual model for assess metrological function management, which links theoretical approaches reviewed; (iii) development and application of a survey questionnaire, based on this conceptual framework; (iv) case study focusing on the metrological function at Exploration and Production Operational Unit of Espírito Santo and its four subunities; (v) formulation of improvement actions for Petrobras metrological function at the selected unities, and suggestions for future research and replication in other organizational contexts. As a conclusion, it can be said that the proposed assessment model fulfilled expectations and assumptions formulated at the very beginning of this research. According to the opinion of managers and teams involved, the model is an useful management and learning tool for improve the management of metrological function and has a large potential for replication in other organizational contexts from the empirical evidences achieved.

[ES] La problemática de los metales pesados en cuerpos de agua superficial se ha observado a nivel mundial y ha sido objeto de múltiples estudios. La presencia de metales en concentraciones por encima de los límites establecidos adquiere mayor relevancia cuando estos se encuentran en fuentes de agua para abastecimiento público. Esta investigación toma como área de estudio a la Microcuenca Milluni, la cual se encuentra cercana de actividades mineras pasadas e ilegales que afectan directamente sobre sus recursos hídricos. Milluni está ubicada en el departamento de La Paz y es una fuente natural de agua para dos ciudades importantes de Bolivia, La Paz y El Alto (540 000 habitantes aproximadamente). El objetivo de esta tesis doctoral es estudiar la implementación de la Ósmosis Inversa (OI) operada a bajas presiones como alternativa sostenible de tratamiento para eliminar la contaminación minera en las aguas de Milluni. Adicionalmente se busca contribuir a la gestión de recursos hídricos, con énfasis en el control de la de calidad de agua en la zona. Esta investigación doctoral se desarrolló en cuatro etapas. En la primera etapa se hizo la caracterización de los cuerpos de agua superficiales para identificar el metal pesado más peligroso presente en Milluni. Para ello, se diseñó un programa de monitoreo considerando las particulares características y limitaciones en la gestión del agua del área. En la segunda etapa del estudio se formularon dos mecanismos para fortalecer la gestión del agua de Milluni, planteando complementar el programa de monitoreo tradicional con la herramienta de teledetección de contaminantes e identificar las partes interesadas de Milluni, para contribuir a la toma de decisiones de la zona. En la tercera etapa de la investigación se diseñó, montó y puso en marcha una planta piloto de OI, tecnología seleccionada debido a su alta eficiencia en la separación de compuestos iónicos del agua. Además, se realizó un diseño de experimentos para estudiar el comportamiento y eficiencia de una membrana tipo ULP 2540 Marca Keensen. Finalmente, en la cuarta etapa se desarrolló un análisis estadístico de los resultados experimentales obtenidos, y la validación de los mismos por medio de un modelo matemático basado en el modelo de concentración de polarización de Spiegler-Kedem. El modelo incluyo un factor de ajuste de temperatura tipo Arrhenius, para obtener una predicción precisa del rendimiento del proceso. Esta tesis doctoral concluye que es posible remover el arsénico presente en aguas sintéticas utilizando la OI operada en condiciones sostenibles de presión (presiones bajas). Se ha demostrado que el uso de esta tecnología a baja presión no afecta a la eficiencia de separación del proceso y contribuye a disminuir el costo energético durante la operación. Este aporte es significativo en situaciones donde se cuenta con pocos recursos económicos y existen riesgos inminentes sobre la salud pública y los ecosistemas, como es el caso de la contaminación del agua por arsénico en Milluni, Bolivia. / [CA] La problemàtica dels metals pesats en cossos d'aigua superficial s'ha observat a nivell mundial i ha segut objecte de múltiples estudis. La presència de metals en concentracions per damunt dels llímits establits adquirix major rellevància quan estos es troben en fonts d'aigua per a abastiment públic. Esta investigació pren com a àrea d'estudi a la Microcuenca Milluni, la qual es troba propenca d'activitats mineres passades i illegals que afecten directament sobre els seus recursos hídrics. Milluni està ubicada en el departament de la Pau i és una font natural d'aigua per a dos ciutats importants de Bolívia, La Pau i L'Alt (540 000 habitants aproximadament). L'objectiu d'esta tesis doctoral és estudiar l'implementació de la Òsmosis Inversa (OI) operada a baixes pressions com a alternativa sostenible de tractament per a eliminar la contaminació minera en les aigües de Milluni. Adicionalment es busca contribuir a la gestió de recursos hídrics, en émfasis en el control de la de calitat d'aigua en la zona. Esta investigació doctoral es va desenrollar en quatre etapes. En la primera etapa es va fer la caracterisació dels cossos d'aigua superficials per a identificar el metal pesat més perillós present en Milluni. Per a això, es va dissenyar un programa de monitoreo considerant les particulars característiques i llimitacions en la gestió de l'aigua de l'àrea. En la segona etapa de l'estudi es varen formular dos mecanismes per a enfortir la gestió de l'aigua de *Milluni, plantejant complementar el programa de monitoreo tradicional en la ferramenta d' teledetección de contaminants i identificar les parts interessades de Milluni, per a contribuir a la presa de decisions de la zona. En la tercera etapa de l'investigació es va dissenyar, va montar i va posar en marcha una planta pilot de OI, tecnologia seleccionada per la seua alta eficiència en la separació de composts iònics de l'aigua. Ademés, es va realisar un disseny d'experiments per a estudiar el comportament i eficiència d'una membrana tipo ULP 2540 Marca Keensen. Finalment, en la quarta etapa es va desenrollar un anàlisis estadístic dels resultats experimentals obtinguts, i la validació dels mateixos per mig d'un model matemàtic basat en el model de concentració de polarisació de Spiegler-Kedem. El model incloc un factor d'ajust de temperatura tipo Arrhenius, per a obtindre una predicció precisa del rendiment del procés. Esta tesis doctoral conclou que és possible remoure l'arsènic present en aigües sintètiques utilisant la OI operada en condicions sostenibles de pressió (pressions baixes). S'ha demostrat que l'us d'esta tecnologia a baixa pressió no afecta a l'eficiència de separació del procés i contribuïx a disminuir el cost energètic durant l'operació. Este aporte és significatiu en situacions a on es conta en pocs recursos econòmics i existixen riscs imminents sobre la salut pública i els ecosistemes, com és el cas de la contaminació de l'aigua per arsènic en Milluni, Bolívia. / [EN] The problem of heavy metals in surface water bodies has been observed worldwide and has been the subject of multiple studies. The presence of metals in concentrations above the established limits becomes more relevant when they are found in water sources for public supply. This research takes the Milluni Micro-basin as a study area, which is close to past and illegal mining activities that directly affect its water resources. Milluni is located in the department of La Paz and is a natural source of water for two important cities in Bolivia, La Paz and El Alto (approximately 540,000 inhabitants). This doctoral thesis aims to study the implementation of Reverse Osmosis (RO) operated at low pressures as a sustainable treatment alternative to eliminate mining contamination in Milluni waters. Additionally, it seeks to contribute to the management of water resources, with an emphasis on the control of water quality in the area. This doctoral research was developed in four stages. In the first stage, surface water bodies were characterized to identify the most dangerous heavy metal present in Milluni. For this, a monitoring program was started considering the particular characteristics and limitations of water management in the area. In the second stage, two mechanisms were formulated to strengthen Milluni's water management, proposing to complement the traditional monitoring study program with the contaminant remote sensing tool and to identify the invited parties of Milluni to contribute to the decision-making of the area. In the third stage of the investigation, a RO pilot plant was worked on, assembled, and started up, a technology selected due to its high efficiency in separating ionic compounds from water. In addition, a design of experiments was carried out to study the behavior and efficiency of a ULP 2540 Keensen brand membrane. Finally, in the fourth stage, a statistical analysis of the experimental results obtained was presented, and their validation using a mathematical model based on the Spiegler-Kedem polarization concentration model. The model includes an Arrhenius-type temperature adjustment factor to accurately predict the process performance. This doctoral thesis concludes that it is possible to remove the arsenic present in synthetic waters using the RO operated under sustainable pressure conditions (low pressures). It has been shown that the use of this technology at low pressure does not affect the separation efficiency of the process and contributes to lower energy costs during operation. This contribution is significant in situations with few economic resources and imminent risks to public health and ecosystems, as is the case of water contamination by arsenic in Milluni, Bolivia. / Alvizuri Tintaya, PA. (2022). Estudio de la ósmosis inversa operada a baja presión como tratamiento de una fuente natural contaminada por actividad minera, en la micro cuenca Milluni en Bolivia, para el abastecimiento de agua segura a poblaciones [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/191428

Scientific Workflows bieten flexible Möglichkeiten für die Modellierung und den Austausch komplexer Arbeitsabläufe zur Analyse wissenschaftlicher Daten. In den letzten Jahrzehnten sind verschiedene Systeme entstanden, die den Entwurf, die Ausführung und die Verwaltung solcher Scientific Workflows unterstützen und erleichtern. In mehreren wissenschaftlichen Disziplinen wachsen die Mengen zu verarbeitender Daten inzwischen jedoch schneller als die Rechenleistung und der Speicherplatz verfügbarer Rechner. Parallelisierung und verteilte Ausführung werden häufig angewendet, um mit wachsenden Datenmengen Schritt zu halten. Allerdings sind die durch verteilte Infrastrukturen bereitgestellten Ressourcen häufig heterogen, instabil und unzuverlässig. Um die Skalierbarkeit solcher Infrastrukturen nutzen zu können, müssen daher mehrere Anforderungen erfüllt sein: Scientific Workflows müssen parallelisiert werden. Simulations-Frameworks zur Evaluation von Planungsalgorithmen müssen die Instabilität verteilter Infrastrukturen berücksichtigen. Adaptive Planungsalgorithmen müssen eingesetzt werden, um die Nutzung instabiler Ressourcen zu optimieren. Hadoop oder ähnliche Systeme zur skalierbaren Verwaltung verteilter Ressourcen müssen verwendet werden. Diese Dissertation präsentiert neue Lösungen für diese Anforderungen. Zunächst stellen wir DynamicCloudSim vor, ein Simulations-Framework für Cloud-Infrastrukturen, welches verschiedene Aspekte der Variabilität adäquat modelliert. Im Anschluss beschreiben wir ERA, einen adaptiven Planungsalgorithmus, der die Ausführungszeit eines Scientific Workflows optimiert, indem er Heterogenität ausnutzt, kritische Teile des Workflows repliziert und sich an Veränderungen in der Infrastruktur anpasst. Schließlich präsentieren wir Hi-WAY, eine Ausführungsumgebung die ERA integriert und die hochgradig skalierbare Ausführungen in verschiedenen Sprachen beschriebener Scientific Workflows auf Hadoop ermöglicht. / Scientific workflows provide a means to model, execute, and exchange the increasingly complex analysis pipelines necessary for today's data-driven science. Over the last decades, scientific workflow management systems have emerged to facilitate the design, execution, and monitoring of such workflows. At the same time, the amounts of data generated in various areas of science outpaced hardware advancements. Parallelization and distributed execution are generally proposed to deal with increasing amounts of data. However, the resources provided by distributed infrastructures are subject to heterogeneity, dynamic performance changes at runtime, and occasional failures. To leverage the scalability provided by these infrastructures despite the observed aspects of performance variability, workflow management systems have to progress: Parallelization potentials in scientific workflows have to be detected and exploited. Simulation frameworks, which are commonly employed for the evaluation of scheduling mechanisms, have to consider the instability encountered on the infrastructures they emulate. Adaptive scheduling mechanisms have to be employed to optimize resource utilization in the face of instability. State-of-the-art systems for scalable distributed resource management and storage, such as Apache Hadoop, have to be supported. This dissertation presents novel solutions for these aspirations. First, we introduce DynamicCloudSim, a cloud computing simulation framework that is able to adequately model the various aspects of variability encountered in computational clouds. Secondly, we outline ERA, an adaptive scheduling policy that optimizes workflow makespan by exploiting heterogeneity, replicating bottlenecks in workflow execution, and adapting to changes in the underlying infrastructure. Finally, we present Hi-WAY, an execution engine that integrates ERA and enables the highly scalable execution of scientific workflows written in a number of languages on Hadoop.