7,274 research outputs found

    Impact of Population Based Indoor Residual Spraying with and without Mass Drug Administration with Dihydroartemisinin-Piperaquine on Malaria Prevalence in a High Transmission Setting: A Quasi-Experimental Controlled Before-and-After Trial in Northeastern Uganda

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    Background: Declines in malaria burden in Uganda have slowed. Modelling predicts that indoor residual spraying (IRS) and mass drug administration (MDA), when co-timed, have synergistic impact. This study investigated additional protective impact of population-based MDA on malaria prevalence, if any, when added to IRS, as compared with IRS alone and with standard of care (SOC). Methods: The 32-month quasi-experimental controlled before-and-after trial enrolled an open cohort of residents (46,765 individuals, 1st enumeration and 52,133, 4th enumeration) of Katakwi District in northeastern Uganda. Consented participants were assigned to three arms based on residential subcounty at study start: MDA+IRS, IRS, SOC. IRS with pirimiphos methyl and MDA with dihydroartemisinin- piperaquine were delivered in 4 co-timed campaign-style rounds 8 months apart. The primary endpoint was population prevalence of malaria, estimated by 6 cross-sectional surveys, starting at baseline and preceding each subsequent round. Results: Comparing malaria prevalence in MDA+IRS and IRS only arms over all 6 surveys (intention-to-treat analysis), roughly every 6 months post-interventions, a geostatistical model found a significant additional 15.5% (95% confidence interval (CI): [13.7%, 17.5%], Z = 9.6, p = 5e−20) decrease in the adjusted odds ratio (aOR) due to MDA for all ages, a 13.3% reduction in under 5’s (95% CI: [10.5%, 16.8%], Z = 4.02, p = 5e−5), and a 10.1% reduction in children 5–15 (95% CI: [8.5%, 11.8%], Z = 4.7, p = 2e−5). All ages residents of the MDA + IRS arm enjoyed an overall 80.1% reduction (95% CI: [80.0%, 83.0%], p = 0.0001) in odds of qPCR confirmed malaria compared with SOC residents. Secondary difference-in-difference analyses comparing surveys at different timepoints to baseline showed aOR (MDA + IRS vs IRS) of qPCR positivity between 0.28 and 0.66 (p \u3c 0.001). Of three serious adverse events, one (nonfatal) was considered related to study medications. Limitations include the initial non-random assignment of study arms, the single large cluster per arm, and the lack of an MDA-only arm, considered to violate equipoise. Conclusions: Despite being assessed at long time points 5–7 months post-round, MDA plus IRS provided significant additional protection from malaria infection over IRS alone. Randomized trials of MDA in large areas undergoing IRS recommended as well as cohort studies of impact on incidence

    Interference mitigation in LiFi networks

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    Due to the increasing demand for wireless data, the radio frequency (RF) spectrum has become a very limited resource. Alternative approaches are under investigation to support the future growth in data traffic and next-generation high-speed wireless communication systems. Techniques such as massive multiple-input multiple-output (MIMO), millimeter wave (mmWave) communications and light-fidelity (LiFi) are being explored. Among these technologies, LiFi is a novel bi-directional, high-speed and fully networked wireless communication technology. However, inter-cell interference (ICI) can significantly restrict the system performance of LiFi attocell networks. This thesis focuses on interference mitigation in LiFi attocell networks. The angle diversity receiver (ADR) is one solution to address the issue of ICI as well as frequency reuse in LiFi attocell networks. With the property of high concentration gain and narrow field of view (FOV), the ADR is very beneficial for interference mitigation. However, the optimum structure of the ADR has not been investigated. This motivates us to propose the optimum structures for the ADRs in order to fully exploit the performance gain. The impact of random device orientation and diffuse link signal propagation are taken into consideration. The performance comparison between the select best combining (SBC) and maximum ratio combining (MRC) is carried out under different noise levels. In addition, the double source (DS) system, where each LiFi access point (AP) consists of two sources transmitting the same information signals but with opposite polarity, is proven to outperform the single source (SS) system under certain conditions. Then, to overcome issues around ICI, random device orientation and link blockage, hybrid LiFi/WiFi networks (HLWNs) are considered. In this thesis, dynamic load balancing (LB) considering handover in HLWNs is studied. The orientation-based random waypoint (ORWP) mobility model is considered to provide a more realistic framework to evaluate the performance of HLWNs. Based on the low-pass filtering effect of the LiFi channel, we firstly propose an orthogonal frequency division multiple access (OFDMA)-based resource allocation (RA) method in LiFi systems. Also, an enhanced evolutionary game theory (EGT)-based LB scheme with handover in HLWNs is proposed. Finally, due to the characteristic of high directivity and narrow beams, a vertical-cavity surface-emitting laser (VCSEL) array transmission system has been proposed to mitigate ICI. In order to support mobile users, two beam activation methods are proposed. The beam activation based on the corner-cube retroreflector (CCR) can achieve low power consumption and almost-zero delay, allowing real-time beam activation for high-speed users. The mechanism based on the omnidirectional transmitter (ODTx) is suitable for low-speed users and very robust to random orientation

    From wallet to mobile: exploring how mobile payments create customer value in the service experience

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    This study explores how mobile proximity payments (MPP) (e.g., Apple Pay) create customer value in the service experience compared to traditional payment methods (e.g. cash and card). The main objectives were firstly to understand how customer value manifests as an outcome in the MPP service experience, and secondly to understand how the customer activities in the process of using MPP create customer value. To achieve these objectives a conceptual framework is built upon the Grönroos-Voima Value Model (Grönroos and Voima, 2013), and uses the Theory of Consumption Value (Sheth et al., 1991) to determine the customer value constructs for MPP, which is complimented with Script theory (Abelson, 1981) to determine the value creating activities the consumer does in the process of paying with MPP. The study uses a sequential exploratory mixed methods design, wherein the first qualitative stage uses two methods, self-observations (n=200) and semi-structured interviews (n=18). The subsequent second quantitative stage uses an online survey (n=441) and Structural Equation Modelling analysis to further examine the relationships and effect between the value creating activities and customer value constructs identified in stage one. The academic contributions include the development of a model of mobile payment services value creation in the service experience, introducing the concept of in-use barriers which occur after adoption and constrains the consumers existing use of MPP, and revealing the importance of the mobile in-hand momentary condition as an antecedent state. Additionally, the customer value perspective of this thesis demonstrates an alternative to the dominant Information Technology approaches to researching mobile payments and broadens the view of technology from purely an object a user interacts with to an object that is immersed in consumers’ daily life

    Management Matters : Organizational Storytelling within the Anthroposophical Society in Sweden

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    The Anthroposophical Society, founded by the Austrian polymath Rudolf Steiner, came to Sweden in 1913, but for the generation of present-day Swedish Anthroposophists whose voices are heard in this study, the great flowering of the movement occurred in the second half of the twentieth century. The movement had by then expanded into a large milieu with many largely independent enterprises and institutions, from the formal organization itself, to various schools, farms, shops, medical facilities, etc., all based on interpretations of Steiner’s legacy. Since then, many members of the movement feel, there has been a decline. A movement of this size and complexity can be seen as a large organization with a corporate-like structure. Taking its point of departure in ideas from the vast field of organization studies, and specifically in the study of storytelling as part of the creation of a corporate culture where many voices and many perspectives co-exist, this study investigates how Anthroposophists in Sweden, both rank and-file members and some who served in leadership positions, tell the story of the putative Golden Age, decline, and projected future of Anthroposophy in Sweden. Twenty-eight interviews were collected, recurrent themes identified, and the plots of the various individual stories analyzed by means of a version of the actantial model developed by the semioticist Algirdas Greimas. The basic storyline, of which the interviewees’ individual stories constitute variations, is that the Golden Age, when charismatic leaders could draw crowds of enthusiastic young people and a vibrant Anthroposophical milieu was built up, came to an end with the demise of those leaders. The present, i.e., the time at which the interviews were conducted, is narratively framed as a period of sharp decline. The vistas for the future come across in most stories as quite bleak. An actantial analysis reveals that the past, an epoch that is on one hand held up as a shining example is on the other hand also described as a time characterized by innumerable problems and conflicts. Disagreement is rampant regarding the reasons for the current decline, and a vast number of problems are identified in the individual narratives. The future is for some interviewees impossible to speculate about, whereas others have specific suggestions for change. These suggestions, when held up against each other, show that there is no unified vision of what the necessary changes might be or who must bring them about. The interviewees agree that Anthroposophy plays a vital role as a spiritual path. When asked how they would describe Anthroposophy and what it more specifically can offer, answers diverge, but substantive descriptions of core concepts or practices are rarely alluded to. Rather, their explanations of what Anthroposophy is are in almost all cases metaphorical or negative, i.e., they represent Anthroposophy as elusive or undefinable. Interviewees can suggest that the lack of a clear Anthroposophical “brand” is a major reason for its current perceived crisis. An analysis of the ways in which Rudolf Steiner is portrayed in the interview material shows that there are a variety of descriptions of him rather than a unified representation of a charismatic leader that members can rally around. This, the study suggests, is because four different forms of charisma can be distinguished on theoretical grounds, and the particular form that permeates the narratives collected for this study does not readily support the dissemination of a centralized, dominant narrative.Antroposofiska SĂ€llskapet, grundat av österrikaren Rudolf Steiner, kom till Sverige redan i 1913, men för den generation av nutida svenska antroposofer vars röster hörs i denna studie intrĂ€ffade rörelsens stora blomstringstid först under nittonhundratalets andra hĂ€lft. Vid det laget hade rörelsen expanderat och blivit till en omfattande miljö med mĂ„nga stort sett oberoende institutioner och verksamheter, frĂ„n sjĂ€lva det Antroposofiska SĂ€llskapet i strikt mening till olika skolor, lantbruk, butiker, kliniker, osv., som alla byggde pĂ„ tolkningar av arvet efter Steiner. MĂ„nga medlemmar i rörelsen menar att det sedan dess har skett en nedgĂ„ng. En rörelse med den storlek och komplexitet som det rör sig om i det aktuella fallet kan betraktas som en organisation med en företagsliknande struktur. Denna studie tar dĂ€rför sin utgĂ„ngspunkt i ett organisationsteoretiskt perspektiv, i synnerhet i den gren av organisationsteorin som studerar berĂ€ttande som ett led i hur en organisationskultur med mĂ„nga samexisterande röster skapas. I det aktuella fallet handlar det om berĂ€ttelser som antroposofer i Sverige, bĂ„de vanliga medlemmar och personer i ledarstĂ€llning, framför om den blomstringstid de menar rörelsen en gĂ„ng hade, den nedgĂ„ng de sĂ€ger sig uppleva och den framtid de förestĂ€ller sig att antroposofin i Sverige kommer att möta. TjugoĂ„tta intervjuer genomfördes och de berĂ€ttelser som förmedlas i dessa intervjuer analyserades med hjĂ€lp av en variant av den aktantmodell som utvecklats av semiotikern Algirdas Greimas. Den grundlĂ€ggande handling man Ă„terfinner i intervjupersonernas olika berĂ€ttelser Ă€r att blomstringstiden var en guldĂ„lder dĂ„ karismatiska ledare kunde samla stora grupper av entusiastiska ungdomar och en levande antroposofisk miljö byggdes upp, men att denna guldĂ„lder upphörde nĂ€r ledarna gick ur tiden. Nuet, alltsĂ„ den tid dĂ„ intervjuerna genomfördes, beskrivs i berĂ€ttelserna som en tid av förfall. Framtidsutsikterna som mĂ„las upp i de flesta berĂ€ttelser Ă€r dystra. Aktantanalysen visar att berĂ€ttelserna om det förflutna bĂ„de beskriver denna tid i mycket positiva termer och nĂ€mner otaliga problem och konflikter. Nuets pĂ„stĂ„dda förfall Ă„terkommer i de flesta berĂ€ttelser, men Ă„sikterna gĂ„r vitt isĂ€r nĂ€r det gĂ€ller vad nutidens problem Ă€r och vad som orsakat dem. Framtiden beskrivs av vissa intervjupersoner som omöjlig att spekulera nĂ€rmare om, medan andra har specifika förslag till förĂ€ndringar. Sammantaget visar analysen att det saknas en enhetlig förestĂ€llning om vad som behöver göras för att lösa rörelsens problem och vem som ska ta ansvar för dessa förĂ€ndringar. Intervjupersonerna Ă€r eniga om att antroposofin spelar en viktig roll. FrĂ„gan hur de skulle beskriva antroposofin och vad den har att erbjuda besvaras pĂ„ olika sĂ€tt, men sĂ€llan i termer av konkreta beskrivningar av för antroposofin centrala förestĂ€llningar eller praktiker. Tendensen Ă€r snarare att svara i metaforiska eller negativa termer, alltsĂ„ genom att berĂ€tta att de menar att antroposofin inte gĂ„r att definiera. Samtidigt kan intervjupersonerna förklara att bristen pĂ„ en tydlig antroposofisk identitet Ă€r ett huvudskĂ€l till vad de ser som rörelsens nuvarande kris. En analys av de sĂ€tt pĂ„ vilka Rudolf Steiner beskrivs i intervjumaterialet visar att det ocksĂ„ finns en rad divergerande uppfattningar av honom snarare Ă€n en sammanhĂ„llen beskrivning av en karismatisk ledare som medlemmarna kan samlas kring. Studien konkluderar att karisma pĂ„ teoretiska grunder kan delas in i fyra olika typer, och att den specifika form av karisma som intervjuerna Ă„terspeglar inte harmonierar sĂ€rskilt vĂ€l med spridandet av en centralt utformad dominerande berĂ€ttelse

    Channel estimation and beam training with machine learning applications for millimetre-wave communication systems

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    The fifth generation (5G) wireless system will extend the capabilities of the fourth generation (4G) standards to serve more users and provide timely communication. To this end, the carriers of 5G systems will be able to operate at higher frequency bands, such as the millimetre-wave (mmWave) bands that span from 30 GHz to 300 GHz, to obtain greater bandwidths and higher data rates. As a result, the deployment of 5G networks is required to accommodate more antennas and offer pervasive coverage with controlled power consumption. The complexity of 5G systems introduces new challenges to traditional signal processing techniques. To address these challenges, a major step is to integrate machine learning (ML) algorithms into wireless communication systems. ML can learn patterns from datasets to achieve control and optimisation of complex radio frequency (RF) networks. This PhD thesis focuses on developing efficient channel estimation methods and beam training strategies with the application of ML algorithms for mmWave wireless systems. Firstly, the channel estimation and signal detection problem is investigated for orthogonal frequency-division multiplexing (OFDM) systems that operate at mmWave bands. A deep neural network (DNN)-based joint channel estimation and signal detection approach is proposed to achieve multi-user detection in a one-shot process for non-orthogonal multiple access (NOMA) systems. The DNN acts as the receiver, which can recover the transmitted data by learning the channel implicitly from suitable training. The proposed approach can be adapted to work for both single-input and single-output (SISO) systems and multiple-output and multipleoutput (MIMO) systems. This DNN-based approach is shown to provide good performance for OFDM systems that suffer from severe inter-symbol interference or where small numbers of pilot symbols are used. Secondly, the beam training and tracking problem is studied for mmWave channels with receiver mobility. To reduce the signalling overhead caused by frequent beam training, a lowcomplexity beam training strategy is proposed for mobile mmWave channels, which searches a set of selected beams obtained based on the recent beam search results. By searching only the adjacent beams to the one recently used, the proposed beam training strategy can reduce the beam training delay significantly while maintaining high transmission rates. The proposed strategy works effectively for channel datasets generated using either the stochastic or the raytracing channel model. This strategy is shown to approach the performance for an exhaustive beam search while saving up to 92% on the required beam training overhead. Thirdly, the proposed low-complexity beam training strategy is enhanced with the use of deep reinforcement learning (DRL) for mobile mmWave channels. A DRL-based beam training algorithm is proposed, which can intelligently switch between different beam training methods such that the average beam training overhead is minimised while achieving good spectral efficiency or energy efficiency performance. Given the desired performance requirement in the reward function for the DRL model, the spectral efficiency or energy efficiency can be maximised for the current channel condition by controlling the number of activated RF chains. The DRL-based approach can adjust the amount of beam training overhead required according to the dynamics of the environment. This approach can provide a good overhead-performance trade-off and achieve higher data rates in channels with significant levels of signal blockage

    The Politics of Local Disaster Management in Thailand, A Poststructuralist Discourse Analysis of Earthquake Governance in the Upper Northern Region

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    Although disaster management has become an effective approach through which the security of society can be secured, it has produced failure and conflict in some circumstances. The academic approach given to this phenomena has often been criticised, namely in relation to how attention is given predominantly to technical and positivist means and thus how social and political dimensions are not adequately considered. Importantly, these neglected factors play a crucial role in determining the success and/or failure of disaster management. Drawing upon Poststructuralist Discourse Theory, this thesis develops a new conceptual framework to critically explain the politics of disaster management, thus revealing the issues that are embedded in the construction of, and political practices involved in responding to, disaster management. It further analyses the politics of disaster management surrounding the 2014 Chiang Rai Earthquake of Thailand. At the national level, the thesis characterises disaster management via four key logics - security, bureaucracy, managerialism and hybridity - showing how their merging in a hybrid form has caused failure/conflict. The discourses that surfaced in this context are demonstrated to have manifested a political space in which local residents used logics of the community to politicise issues and to challenge the state. Conversely, logics of uncertainty and professionalisation were used as de/re-politicisation mechanisms by provincial agencies to regain authority. This thesis considers such disaster management as contested political terrain where political strategies were implemented through anti- and pro-central disaster management projects. The thesis contributes to Disaster Management Studies in three ways – by offering an alternative means of conducting research as to disaster management politics, exemplifying the benefits of applying a logics approach in explaining the political practices involved in disaster management and calling for further analysis to be given as to the role of subjective desires and the affective register in this field

    Towards the development of care management in community care for elderly people in Korea

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    This study is concerned with the feasibility of several forms of care management in the development of community care for elderly people in Korea. Chapter one introduces the background of community care in Korea in the light of demographic, socio-economic, and political realities. This chapter reviews the changing Korean society as a barometer to understand the scope, size, and speed of social needs, especially community care for elderly people, over the last few decades. Chapter two explores various definitions, concepts, and theories of community, community care, and care management by building upon trends previously established in the research. This helps to identify the different models of care management and the pre-conditions necessary for the application of different models in Korea. Chapter three explores what factors have affected the development of community care, and what community dare has achieved for elderly people in the UK. Especially, care management in community care for elderly people in the UK is examined in detail. Chapter four details the findings of field research on community care for elderly people in Korea. This covers the needs of elderly people and their carers, and the social worker's tasks and available resources. The potential for the use of care management based on the findings of field research is assessed. Chapter five investigates whether the UK models of care management are suitable for Korean society, which interventions are useful for developing care management, and the strategies, and principles involved

    Smart-antenna techniques for energy-efficient wireless sensor networks used in bridge structural health monitoring

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    Abstract: It is well known that wireless sensor networks differ from other computing platforms in that 1- they typically require a minimal amount of computing power at the nodes; 2- it is often desirable for sensor nodes to have drastically low power consumption. The main benefit of the this work is a substantial network life before batteries need to be replaced or, alternatively, the capacity to function off of modest environmental energy sources (energy harvesting). In the context of Structural Health Monitoring (SHM), battery replacement is particularly problematic since nodes can be in difficult to access locations. Furthermore, any intervention on a bridge may disrupt normal bridge operation, e.g. traffic may need to be halted. In this regard, switchbeam smart antennas in combination with wireless sensor networks (WSNs) have shown great potential in reducing implementation and maintenance costs of SHM systems. The main goal of implementing switch-beam smart antennas in our application is to reduce power consumption, by focusing the radiated energy only where it is needed. SHM systems capture the dynamic vibration information of a bridge structure in real-time in order to assess the health of the structure and to predict failures. Current SHM systems are based on piezoelectric patch sensors. In addition, the collection of data from the plurality of sensors distributed over the span of the bridge is typically performed through an expensive and bulky set of shielded wires which routes the information to a data sink at one end of the structure. The installation, maintenance and operational costs of such systems are extremely high due to high power consumption and the need for periodic maintenance. Wireless sensor networks represent an attractive alternative, in terms of cost, ease of maintenance, and power consumption. However, network lifetime in terms of node battery life must be very long (ideally 5–10 years) given the cost and hassle of manual intervention. In this context, the focus of this project is to reduce the global power consumption of the SHM system by implementing switched-beam smart antennas jointly with an optimized MAC layer. In the first part of the thesis, a sensor network platform for bridge SHM incorporating switched-beam antennas is modelled and simulated. where the main consideration is the joint optimization of beamforming parameters, MAC layer, and energy consumption. The simulation model, built within the Omnet++ network simulation framework, incorporates the energy consumption profiles of actual selected components (microcontroller, radio interface chip). The energy consumption and packet delivery ratio (PDR) of the network with switched-beam antennas is compared with an equivalent network based on omnidirectional antennas. In the second part of the thesis, this system model is leveraged to examine two distinct but interrelated aspects: Gallium Arsenide (GaAs) based solar energy harvesting and switched-beam antenna strategies. The main consideration here is the joint optimization of solar energy harvesting and switchedbeam directional antennas, where an equivalent network based on omnidirectional antennas acts as a baseline reference for comparison purposes.Il est bien connu que les rĂ©seaux de capteurs sans fils diffĂšrent des autres plateformes informatiques Ă©tant donnĂ© 1- qu’ils requiĂšrent typiquement une puissance de calcul minimale aux noeuds du rĂ©seau ; 2- qu’il est souvent dĂ©sirable que les noeuds capteurs aient une consommation d’énergie dramatiquement faible. La principale retombĂ©e de ce travail rĂ©side en la durĂ©e de vie allongĂ©e du rĂ©seau avant que les piles ne doivent ĂȘtre remplacĂ©es ou, alternativement, la capacitĂ© de fonctionner indĂ©finiment Ă  partir de modestes sources d’énergie ambiente (glĂąnage d’énergie). Dans le contexte du contrĂŽle de la santĂ© structurale (CSS), le remplacement de piles est particuliĂšrement problĂ©matique puisque les noeuds peuvent se trouver en des endroits difficiles d’accĂšs. De plus, toute intervention sur un pont implique une perturbation de l’opĂ©ration normale de la structure, par exemple un arrĂȘt du traffic. Dans ce contexte, les antennes intelligentes Ă  commutation de faisceau en combinaison avec les rĂ©seaux de capteurs sans fils ont dĂ©montrĂ© un grand potentiel pour rĂ©duire les coĂ»ts de rĂ©alisation et d’entretien de systĂšmes de CSS. L’objectif principal de l’intĂ©gration d’antennes Ă  commutation de faisceau dans notre application rĂ©side dans la rĂ©duction de la consommation Ă©nergĂ©tique, rĂ©alisĂ©e en concentrant l’énergie radiĂ©e uniquement lĂ  oĂč elle est nĂ©cessaire. Les systĂšmes de CSS capturent l’information dynamique de vibration d’une structure de pont en temps rĂ©el de maniĂšre Ă  Ă©valuer la santĂ© de la structure et prĂ©dire les failles. Les systĂšmes courants de CSS sont basĂ©s sur des senseurs piĂ©zoĂ©lectriques planaires. De plus, la collecte de donnĂ©es Ă  partir de la pluralitĂ© de senseurs distribuĂ©s sur l’étendue du pont est typiquement effectuĂ©e par le biais d’un ensemble coĂ»teux et encombrant de cĂąbles blindĂ©s qui vĂ©hiculent l’information jusqu’à un point de collecte Ă  une extremitĂ© de la structure. L’installation, l’entretien, et les coĂ»ts opĂ©rationnels de tels systĂšmes sont extrĂȘmement Ă©levĂ©s Ă©tant donnĂ© la consommation de puissance Ă©levĂ©e et le besoin d’entretien rĂ©gulier. Les rĂ©seaux de capteurs sans fils reprĂ©sentent une alternative attrayante, en termes de coĂ»t, facilitĂ© d’entretien et consommation Ă©nergĂ©tique. Toutefois, la vie de rĂ©seau en termes de la durĂ©e de vie des piles doit ĂȘtre trĂšs longue (idĂ©alement de 5 Ă  10 ans) Ă©tant donnĂ© le coĂ»t et les problĂšmes liĂ©s Ă  l’intervention manuelle. Dans ce contexte, ce projet se concentre sur la rĂ©duction de la consommation de puissance globale d’un systĂšme de CSS en y intĂ©grant des antennes intelligentes Ă  commutation de faisceau conjointement avec une couche d’accĂšs au mĂ©dium (couche MAC) optimisĂ©e. Dans la premiĂšre partie de la thĂšse, une plateforme de rĂ©seau de capteurs sans fils pour le CSS d’un pont incorporant des antennes Ă  commutation de faisceaux est modĂ©lisĂ© et simulĂ©, avec pour considĂ©ration principale l’optimisation des paramĂštres de sĂ©lection de faisceau, de la couche MAC et de la consommation d’énergie. Le modĂšle de simulation, construit dans le logiciel de simulation de rĂ©seaux Omnet++, incorpore les profils de consommation d’énergie de composants rĂ©els sĂ©lectionnĂ©s (microcontrĂŽleur, puce d’interface radio). La consommation d’énergie et le taux de livraison de paquets du rĂ©seau avec antennes Ă  commutation de faisceau est comparĂ© avec un rĂ©seau Ă©quivalent basĂ© sur des antennes omnidirectionnelles. Dans la deuxiĂšme partie de la thĂšse, le modĂšle systĂšme proposĂ© est mis Ă  contribution pour examiner deux aspects distrincts mais interreliĂ©s : le glĂąnage d’énergie Ă  partir de cellules solaire Ă  base d’arsĂ©niure de Gallium (GaAs) et les stratĂ©gies liĂ©es aux antennes Ă  commutation de faisceau. La considĂ©ration principale ici est l’optimisation conjointe du glĂąnage d’énergie et des antennes Ă  commutation de faisceau, en ayant pour base de comparaison un rĂ©seau Ă©quivalent Ă  base d’antennes omnidirectionnelles

    Supply Chain Finance Adoption:Three is a Crowd in Entangled Relationships

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    Supply Chain Finance (SCF) has gained increasing attention in recent years – for both favourable reasons, e.g. the critical need for working capital during economic recovery, and adverse reasons, e.g. high-profile scandals and abuses of SCF reported in the media such as Greensill and Carillion. The SCF literature has primarily focused on the economic advantages of SCF, and a so-called win-win-win approach claiming that all the parties involved , e.g. the bank, buyer, and supplier, would all benefit from SCF arrangements. Even though previous research on the adoption of SCF has pointed to the reluctance of firms, especially suppliers, to adopt SCF, the literature has given most attention to large focal firms, placing less emphasis on their supply chain partners. Yet supplier reluctance is also important to these focal firms as the successful implementation of SCF is determined by the degree of participation and frequency of transactions with suppliers. This has produced a need to systemically understand how small, less powerful non-focal firms construct their understandings of SCF and make decisions about SCF participation. This thesis investigates the understandings of, and the decision to adopt, SCF primarily in SMEs, both upstream as suppliers and downstream as distributors, in two different settings ─ the UK, where SCF is relatively well developed, and Thailand where SCF recently started in 2016. Given the dissensus in the literature regarding the appropriate theoretical underpinnings, this study employs a grounded theory-based methodology in which no theory was committed to before data collection and analysis, allowing for a substantive theory of SCF relationships to emerge from the collected data. This involved 56 interviews with SMEs, banks and subject experts as well as analysis of supporting documents. Consistent with grounded theory, the study sought to identify the main concern of the research participants and the way in which they dealt with this identified main concern. Through a constant comparative analysis of interview data, supporting documents, and relevant literature, the emergent main concern or core category was identified as the ‘Dyadic - Triadic distinction’. This distinction was between dyadic forms of SCF, in which informants had relatively independent relationships in their physical and financial supply chains, and triadic forms, in which relationships were entangled in some way. Triadic forms appeared to be inherently problematic, leading to the thesis that ‘Three is a Crowd’. Participants dealt with this main concern through five interrelated categories of concern ─ Risk, Relationship, Awareness, Control, and Context. Following the emergence of the main concern or core category and the five interrelated categories, a systematic analysis was undertaken of how transaction cost economics (TCE), which was identified as the most appropriate formal theory, could and could not account for the findings. For example, many of the findings could be interpreted in terms of opportunism and information impactedness, but there were concerns with relationships and control that could not be explained by TCE. From this analysis a qualitative model of how SMEs understood and made decisions to adopt SCF was proposed. In addition, a more detailed model was developed to show the significance of signalling concerns in the findings. The main contribution of this thesis is to show how the firms often meant to be the primary beneficiaries of SCF – SMEs – are much less concerned with technical advantages (such as lower financing cost), and much more concerned with the relational consequences of participating in more complex triadic forms of SCF. The key practical implication that is drawn is that focal firms need to be aware, when offering triadic SCF to their smaller supply chain partners, that these partners often have existing dyadic SCF relationships. Therefore, their decision to adopt an offered triadic SCF is not straightforward, but involves participating in a new relationship and at the same time having to maintain or reduce existing ones ─ often including both financing and supply chain relationships
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