Ph. D. (Department of Business Administration, Faculty of Management Sciences), Vaal University of Technology. / The Small and Medium Enterprise (SME) sector has been receiving increased global attention from governments, researchers and management practitioners in both developed and developing nations as a vehicle for economic growth. The Zimbabwean SME sector has been on record as minimising the impact of the economic challenges on the economy thus proving the strategic role played by the SME sector in improving economic growth. Therefore, the Zimbabwean government has high hopes of resuscitating the economy through empowering the SME sector. However, the sector is inundated by challenges that have retarded its effectiveness in achieving the government’s expectations. Some key limitations and challenges include short life span of the SMEs, entrenchment of archaic business practices, lack of financial capitalisation and the failure to adopt a supply chain perspective of business. Although several solutions to the problem have been proposed and implemented, one solution that has not been fully tested relates to how people-centred knowledge management systems (KMSs) can be harnessed to improve the performance of SME supply chains in Zimbabwe. Therefore, the purpose of this study was to investigate the relationships between people-centred KMSs, knowledge sharing and supply chain performance (SCP) in the Zimbabwean SME sector. The study adopted a quantitative research method in which a survey design was implemented in collecting the data that were used to test the relationships on people-centred KMSs (i.e. communities of practice (CoPs), innovation management, organisational culture and social capital); knowledge sharing and SCP (i.e. time-related performance (TRP), cost-related performance (CRP), responsiveness-related performance (RRP) and operation quality-related performance (OQRP). A structured survey questionnaire was designed using measurement scales adapted from extant literature and it was administered to a sample of 580 SME owners, managers and employees who had some prior understanding of knowledge management, information technology and supply chain management. The collected data were analysed using the Statistical Packages for Social Sciences (SPSS) Version 25.0 and the Analysis of Moment Structures (AMOS) Version 25.0 statistical software. The data were analysed using both descriptive and inferential statistics. The statistical techniques used included measures of central tendency, cross-tabulations, factor analysis, multiple linear regression analysis, path analysis and structural equation modelling. The results of the study showed that SME employer qualifications (Kendall-tau = 0.88; p=.000), work experience (Kendall-tau = 0.86; p=.001) and nationality (Kendall-tau = 0.79; p=.010) as well as SME business sector (Kendall-tau = 0.89; p=.000) can be used to predict SME life span in the Zimbabwe SME sector. The results also showed significant relationships between three people-centred KMSs, namely, CoP (β=0.639, t=9.656, p=0.000), innovation management (β =-0.337, t=-8.578, p=0.000) and organisational culture (β=-0.261, t=-4.083, p=0.000) and knowledge sharing. The relationship between social capital and knowledge sharing was insignificant (β=-0.076, t=0.177, p=0.859). Significant relationships were also realised on knowledge sharing and three process-based SCP sub- factors, namely, TRP (β=0.231, t=4.717, p=0.000), CRP (β=-0.082, t=-2.015, p=0.044) and RRP (β=-0.177, t=-3.621, p=0.000). No relationship was found between knowledge sharing and OQRP (β=-0.076, t=0.049, p=0.254). Moreover, knowledge sharing was found to have a full mediation effect on people-centred KMSs and process-based SCP while no mediation effect was found with network-based SCP. The study makes substantial contributions to the existing body of knowledge. Theoretically, it provides in-depth insights of people-centred KMSs in SME SCP for developing countries such as Zimbabwe, which is an under researched area, thus expanding extant literature on the subject. From a knowledge management perspective, the study proposes the utilisation of SMEs’ socio-demographic factors to predict SMEs’ continued existence, thereby enabling financial institutions to offer financial assistance to such businesses with confidence. For governments in developing countries, the study suggests that specific attention should be directed to knowledge-based supply chains that adopt people-centred KMSs and process-based SCP to consider them as a possible alternative in addressing performance challenges in SME sectors.

Event Stream Processing (ESP) Systeme überwachen kontinuierliche Datenströme, um benutzerdefinierte Queries auszuwerten. Die Herausforderung besteht darin, dass die Queryverarbeitung zustandsbehaftet ist und die Anzahl von Teilübereinstimmungen mit der Größe der verarbeiteten Events exponentiell anwächst. Die Dynamik von Streams und die Notwendigkeit, entfernte Daten zu integrieren, erschweren die Zustandsverwaltung. Erstens liefern heterogene Eventquellen Streams mit unvorhersehbaren Eingaberaten und Queryselektivitäten. Während Spitzenzeiten ist eine erschöpfende Verarbeitung unmöglich, und die Systeme müssen auf eine Best-Effort-Verarbeitung zurückgreifen. Zweitens erfordern Queries möglicherweise externe Daten, um ein bestimmtes Event für eine Query auszuwählen. Solche Abhängigkeiten sind problematisch: Das Abrufen der Daten unterbricht die Stream-Verarbeitung. Ohne eine Eventauswahl auf Grundlage externer Daten wird das Wachstum von Teilübereinstimmungen verstärkt. In dieser Dissertation stelle ich Strategien für optimiertes Zustandsmanagement von ESP Systemen vor. Zuerst ermögliche ich eine Best-Effort-Verarbeitung mittels Load Shedding. Dabei werden sowohl Eingabeeevents als auch Teilübereinstimmungen systematisch verworfen, um eine Latenzschwelle mit minimalem Qualitätsverlust zu garantieren. Zweitens integriere ich externe Daten, indem ich das Abrufen dieser von der Verwendung in der Queryverarbeitung entkoppele. Mit einem effizienten Caching-Mechanismus vermeide ich Unterbrechungen durch Übertragungslatenzen. Dazu werden externe Daten basierend auf ihrer erwarteten Verwendung vorab abgerufen und mittels Lazy Evaluation bei der Eventauswahl berücksichtigt. Dabei wird ein Kostenmodell verwendet, um zu bestimmen, wann welche externen Daten abgerufen und wie lange sie im Cache aufbewahrt werden sollen. Ich habe die Effektivität und Effizienz der vorgeschlagenen Strategien anhand von synthetischen und realen Daten ausgewertet und unter Beweis gestellt. / Event stream processing systems continuously evaluate queries over event streams to detect user-specified patterns with low latency. However, the challenge is that query processing is stateful and it maintains partial matches that grow exponentially in the size of processed events. State management is complicated by the dynamicity of streams and the need to integrate remote data. First, heterogeneous event sources yield dynamic streams with unpredictable input rates, data distributions, and query selectivities. During peak times, exhaustive processing is unreasonable, and systems shall resort to best-effort processing. Second, queries may require remote data to select a specific event for a pattern. Such dependencies are problematic: Fetching the remote data interrupts the stream processing. Yet, without event selection based on remote data, the growth of partial matches is amplified. In this dissertation, I present strategies for optimised state management in event pattern detection. First, I enable best-effort processing with load shedding that discards both input events and partial matches. I carefully select the shedding elements to satisfy a latency bound while striving for a minimal loss in result quality. Second, to efficiently integrate remote data, I decouple the fetching of remote data from its use in query evaluation by a caching mechanism. To this end, I hide the transmission latency by prefetching remote data based on anticipated use and by lazy evaluation that postpones the event selection based on remote data to avoid interruptions. A cost model is used to determine when to fetch which remote data items and how long to keep them in the cache. I evaluated the above techniques with queries over synthetic and real-world data. I show that the load shedding technique significantly improves the recall of pattern detection over baseline approaches, while the technique for remote data integration significantly reduces the pattern detection latency.

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<p> Design and optimization of aircraft thermal management systems (TMS) is typically conducted by considering a single system architecture at steady-state conditions, using per?formance metrics such as bleed air flow rate, fuel burn flow rate, or total system mass. However, when trying to increase the overall performance of a legacy system or analyzing new system architectures, it can be difficult to identify how individual component or sub?system changes will propagate throughout the overall TMS. In this thesis, new knowledge and tools are presented that will advance the use of exergy-based design techniques for next generation aircraft thermal management systems (TMS). This is motivated by the fact that exergy destruction is a quantity that can be calculated for any subsystem or component, regardless of energy domain or function. The relationship between exergy destruction min?imization (EDM) and conventional design metrics is investigated and quantified. This is performed through the use of a steady-state analysis and by leveraging a high fidelity model of a complex TMS. It is shown that exergy destruction is not only sensitive to individual component parameters in a manner consistent with conventional performance metrics, but that due to its generalizability, it also captures how changes in one subsystem propagate throughout the overall TMS. Specifically, through a design case study, it is shown that minimizing system-wide exergy destruction rate (without an engine model) yields a similar engine fuel burn rate as when fuel burn is minimized directly, but also results in a signif?icantly lower system mass. Building on these results, a transient design and analysis tool for TMS is developed using a graph theoretic approach. The tool is used on a case study of an air cycle machine (ACM) and on an architecture enumeration case study for a notional TMS. The transient exergy-based analysis is shown to provide insight into how efficiently energy is used at a component level, and captures the differences in thermal performance between architectures. </p>

E-handelslösningar tillhandahåller inköpsfunktioner för användare på produkter online, men Internetanvändare är känsliga för förseningar. Användare ser webbplatsens laddningstid egenskap. Användarna är även känsliga för kognitiv laddningstid, vilket har att göra med upplevda estetik av en webbplats och mentala modeller som skapas från tidigare interaktion med webbplatser. Omfattningen av examensarbetet är att fyra e-handels content management system (CMSs) jämförs i denna avhandling att se vilka utför med den lägsta sidan laddningstid. dessa är Magento, Drupal med commerce, Wordpress med woocommerce och Joomla med Hikashop. Alla CMS förvandlas till liknande design baserat på en universell tema, med hjälp av twitter bootstrap ramverket. Designen är baserad på tidigare forskning för användarnas mentala modeller för e-handel webbplatser. En fullt fungerande fiktiv plats Fastcommerce utvecklas på dessa fyra CMS. CMSn är fyllda med en kategori sida identiska prov elektroniska produkter (12 artiklar). Produkterna har bilder och lorem ipsum text. Metoden för examensarbetet är experiment. Experimenten utförs för att hitta den sida laddningstid på en lokal miljö. Resultaten visar tydliga resultatförbättringar på alla fyra CMSs efter tillämpade optimeringar. Men några av de optimeringar orsakar negativakonsekvenser prestanda. / E-commerce solutions are providing purchasing capabilities to users on products online, but Internet users are sensitive to delays. In-fact users see page load time as a website feature. Users are also sensitive to cognitive load time, which has to do with perceived aesthetics of a website and mental models which are created from previous interaction with websites.The scope of the thesis is that four commerce content management systems (CMSs) are compared in this thesis to find out which performs with the lowest page load time. These are Magento, Drupal with commerce, Wordpress with woocommerce and Joomla with Hikashop. The CMSs are all pushed to a very similar website design based on one universal theme, using the twitter bootstrap mobile first responsive framework. The design is based on previousresearch of users mental models for e-commerce websites. A fully functional fictional site Fastcommerce is developed on the four CMSs. The CMSs are filled with one category page of identical sample electronic products (12 items). The products have images and lorem ipsum text. The method of the thesis are experiments. The experiments are conducted to find the page load time on a local environment. The results show clear performance improvements on all four CMSs after applied optimizations. But some of the optimizations cause negative performance consequences.

With increased demand for housing in Sweden's metropolitan regions, it is of greatimportance to meet the need and build more. The supply of housing is governed byaccess to land and what it costs to build apartment houses. In Sweden, there is ahistory of cartel formation of contractors and at the turn of the millennium, thegovernment invested funds to create increased price transparency in theconstruction sector. Based on this, the purpose of this project is to investigate how itis possible to today produce housing more economically, while maintaining quality.The study is limited to the purchase of prefabricated hollow core and load-bearingwall elements in both concrete and wood. The goal is to be able to compare prices ofthese construction parts between Swedish and foreign suppliers. The foreignsuppliers are limited to the ones operating in the Baltic countries and Poland. Thus, itmust be investigated which of the wooden or concrete frames is most economicallyprofitable, what opportunities there are with international purchases of frameelements and what should be taken into account in international purchases. / I och med ökad efterfrågan på bostäder i Sveriges storstadsregioner är det av vikt atti samma takt öka utbudet. Utbudet styrs av tillgång till mark samt vad det kostar attbygga. I Sverige finns en historia av kartellbildning av byggföretag och regeringensatte vid millennieskiftet in medel för att skapa ökad pristransparens inombyggsektorn. Med bakgrund i detta är syftet med examensarbetet att undersöka hurdet idag går att producera bostäder mer ekonomiskt, med bibehållen kvalitet iåtanke. Studien avgränsas till inköp av prefabricerade håldäck och bärandeväggelement i betong respektive trä. Målet är att kunna jämföra priser av dessakonstruktionsdelar mellan svenska och utländska leverantörer. De utländskaleverantörerna avgränsas till att verka inom baltikum och Polen. Således ska detutredas vad utav trä- eller betongstomme som är mest ekonomiskt lönsamt, vilkamöjligheter som finns med internationella inköp av stomelement samt vad som börtas hänsyn till vid internationella inköp.De risker som finns kopplade till just internationella inköp är bland andra risk attprodukten inte stämmer överens med vad som avtalats och leveransförseningar.Logistikrisker begränsas med hjälp av avtal reglerade utifrån det internationellaregelverket Incoterms. Det finns även politiska och valutarelaterade risker medinternationell handel.ISO 9000 är ett kvalitetsledningssystem som ligger till grund för att företag ochorganisationer ska kunna säkerställa att kvaliteten i deras arbete svarar upp motkundens behov och krav. ISO 14000 samlar standarder inom miljöledningssystem.Intervjuer av sex svenska och fem utländska leverantörer om pris och kvalitetsarbetegav intressanta resultat för studien. Samtliga utländska leverantörer är certifierademed ISO 9001 samt ISO 14001. Två av sex svenska bolag har ISO9001-certifieringen och hälften ISO 14001-certifieringen. Att köpa prefabriceradebetongelement är enligt studien inte ekonomiskt lönsammare i utlandet, det är detdäremot att köpa träelement.

Effects of the environmental degradation in the last century rose awareness on the need to manage natural resources in a more sustainable manner. The role of the private sector in greenhouse gases emissions and resources use is significant and hence encompasses huge potential to mitigate the environmental impact of human activities. Environmental Management Systems (EMS) has been regarded as an effective way to manage the environmental impact of enterprises. Factors impacting the performance of EMS in French enterprises are investigated. Three aspects of EMS are studied: managerial processes, policy-making process and tools used to monitor environmental impact. Influence of sectorial activity on EMS is studied. In the first phase, a qualitative research approach is used, and twenty-one French enterprises from different sectors are interviewed. Two types of employees are surveyed: employees in charge of the environmental policy within the enterprise, and employees not related to environmental policies. In the second phase, exploratory factor analysis is employed to identify practices leading to best environmental performance. Results from the exploratory analysis reveal that firms with the highest environmental performance tend to have a long-term agenda and consult external stakeholders, namely their customers, to elaborate their environmental policy. Regarding communication channels to educate employees on sustainable practices, it is found that executives are often more informed on sustainable practices and are not responsive to same channels. Results from the qualitative analysis show lack of financial support is still the first obstacle to EMS implementation, and business strategy is rarely aligned with the environmental strategy of the company. Therefore, there is a strong need to create a compelling business case for EMS. / Effekterna av miljöförstöring under förra seklet ökade medvetenheten om behovet av att hantera resurser på ett mer hållbart sätt. Den privata sektorns roll i utsläpp av växthusgaser och resursanvändning är betydande och omfattar därför en enorm potential för att påverka miljöns hållbarhet. Environmental Management Systems (EMS) har betraktats som ett effektivt sätt att hantera företagens miljöpåverkan. Faktorer som påverkar resultatet av EMS i franska företag undersöks. Tre aspekter av EMS studeras: ledningsprocesser, beslutsfattande och verktyg som används för att övervaka miljöpåverkan. Påverkan av sektoraktivitet på EMS studeras. I den första fasen används en kvalitativ forskningsmetod och 21 franska företag från olika sektorer intervjuas. Två typer av anställda undersöks: anställda som ansvarar för miljöpolitiken inom företaget och anställda som inte är relaterade till miljöpolitiken. I den andra fasen används undersökande faktoranalys för att identifiera metoder som leder till bästa miljöprestanda. Resultat från den undersökande analysen visar att företag med högsta miljöprestanda tenderar att ha en långsiktig agenda och konsultera externa intressenter, nämligen deras kunder, för att utarbeta sin miljöpolicy. Beträffande kommunikationskanaler för att utbilda anställda om hållbar praxis, konstateras att chefer ofta är mer informerade om hållbara metoder och inte svarar på samma kanaler. Resultat från den kvalitativa analysen visar att bristen på ekonomiskt stöd fortfarande är det första hinderet för implementering av EMS, och affärsstrategi är sällan i linje med företagets miljöstrategi. Därför finns det ett starkt behov av att skapa ett övertygande affärsfall för EMS.

Yes / Energy consumption (EC) of consumers primarily depends on comfort level (CL) affirmed by brain sensations of the central nervous system. Environmental parameters such as surroundings, relative humidity, air temperature, solar irradiance, air pressure, and cloud cover directly influence consumer body temperature that in return affect blood dynamics perturbing brain comfort sensations. This CL (either in summer, winter, autumn, or spring season) is a function of external environment and internal body variations that force a consumer toward EC. To develop a new concept of consumer's EC, first the authors described environment parameters in detail with relation to surroundings and EC. Considering this, they tabulated a generic relation of consumer's CL with EC and environment temperature. Second, to build an inter-related bond between the environmental effects on consumer body dynamics, they analysed theoretically and mathematically above mutual relations between medical and environmental sciences. Finally, they present their conceptual EC model based on a closed-loop feedback system. This model is a complex non-linear adaptive system with environmental and surrounding parameters as input to the system resulting in an optimised EC, considering consumer CL as a key parameter for the system.

This research presents a two-part study on a fuel cell electric van (FCEV), focusing on vehicle modelling and developing different control strategies for the modelled vehicle. The modelling phase accounts for the aging effects on the fuel cell (FC) and battery, analyzing FCEV behavior over time. This includes estimating and integrating the degradation impacts on characteristic curves, such as the FC’s polarization and efficiency curves, the battery’s charging and discharging resistance curves, and the open-circuit voltage curve. A simplified fuel cell system (FCS) model is designed to consider power losses in multiple components, including the FC stack, air compressor, and others. The dynamic limits of the FC are also included to yield more realistic results. The model is based on the vehicle Opel Vivaro FC specifications, incorporating parameters like maximum FC power, battery capacity, vehicle weight, and tire dimensions. Subsequently, various control strategies are applied to analyze their effectiveness in FC and battery State-of-Health (SOH) degradation and hydrogen consumption. A rule-based energy management system (EMS) is implemented first, which operates with five different operational modes dependent on the vehicle’s state. This is followed by a look-up table (LUT) based strategy, which uses two two-dimensional tables generated by a Neural Network (NN). The network is trained with discretized optimal / Thesis / Master of Applied Science (MASc)