Thèses sur le sujet « Efficienza investigativa »

L’ordine europeo di indagine penale, introdotto dalla direttiva 2014/41/UE, è uno strumento di cooperazione giudiziaria nel settore delle prove divenuto imprescindibile a fronte della crescente dimensione transnazionale assunta dalla criminalità, quale conseguenza dell’evaporazione dei confini geografici nello Spazio di libertà, sicurezza e giustizia dell’Unione europea. La direttiva sovranazionale, recepita nell’ordinamento italiano attraverso il d.lgs. n. 108 del 2017, ha dato vita a un istituto avente natura ibrida, animato dal principio del reciproco riconoscimento, che conserva, al contempo, alcuni tratti tipici della mutua assistenza giudiziaria tradizionale, nel tentativo di coniugare l’efficienza investigativa e la tutela delle garanzie fondamentali. Sullo sfondo di un contesto caratterizzato dall’assenza di armonizzazione tra le regole processuali e probatorie nazionali, il meccanismo di acquisizione della prova all’estero ruota attorno al principio di proporzionalità, che prende forma nel giudizio di bilanciamento, da condursi in concreto tenendo conto delle peculiarità del caso, tra le esigenze connesse all’accertamento del reato e il sacrificio imposto ai diritti delle persone a vario titolo coinvolte nelle procedure di emissione ed esecuzione dell’ordine. La presente tesi di dottorato intende fornire un’analisi a trecentosessanta gradi dell’ordine europeo d’indagine, prendendo le mosse dalla disciplina normativa, con l’obiettivo di mettere in luce le principali problematiche emerse nelle sue prime esperienze applicative e individuare soluzioni in grado di accorciare le distanze che separano teoria e prassi. A tal fine, ampio spazio è dedicato alla ricostruzione delle prime pronunce giurisprudenziali rese sul tema dalla Corte di giustizia e dalla Corte di cassazione, che rivelano complessivamente la tendenza a prediligere le istanze di efficienza investigativa a scapito dei diritti della difesa, per poi esporre, in chiave critica, alcuni casi pratici selezionati presso le Procura della Repubblica di Milano e di Monza
The European criminal investigation order, introduced by Directive 2014/41/EU, is an instrument of judicial cooperation in the field of evidence, which has become necessary, given the growing transnational dimension of crime as a result of the sublimation of geographical boundaries in the European Union's Area of Freedom, Security and Justice. The supranational directive, implemented by Italian Legislative Decree no. 108 of 2017, has given rise to a construct of hybrid nature, inspired by the principle of mutual recognition, which maintains, at the same time, certain features typical of traditional mutual legal assistance, in an attempt to combine investigative efficiency and protection of fundamental guarantees. In an underlying backdrop still characterized by the absence of harmonization of national procedural and evidentiary rules, the mechanism for adducing evidence in a foreign country revolves around the principle of proportionality, which in turn takes shape in the context of a balancing judgement - to be conducted in the actual case and taking into consideration the specificities of such case - between the needs related to the detection of crime and the sacrifices imposed on the rights of the persons involved, for various reasons, in the procedures aimed at issuing and executing the relevant order. This doctoral thesis intends to provide a comprehensive analysis of the European Investigation Order, beginning with its legal framework, for the purposes of highlighting the main problems that have emerged in its early-stage enforcement and of identifying solutions capable of shorten the gap between theory and practice. To this end, a large space is firstly dedicated to the analysis of the early case-law rendered by the Court of Justice and by the Italian Court of Cassation on this theme, which reveals the overall tendency to prefer purposes of investigatory efficiency to the detriment of defense rights; secondly, this thesis critically evaluates some practical cases selected at the Public Prosecutor's Office of Milan and Monza.

This study investigates Compressed Air Energy Storage (CAES) application in the electrical power and transportation industries. Information concerning current CAES projects is presented. A thorough thermodynamic analysis of the CAES process is completed; including theoretical efficiency determination for several variants of the compression and expansion processes. Industry claimed efficiencies ranging from 26% to 82% are presented and explained. Isothermal and Isentropic efficiency baselines are developed. Energy density of compressed air on both a mass and volume basis is compared to other energy storage methods. Best expected efficiency of a hypothetical CAES system is determined to be 34% using currently achievable efficiencies and 63% considering 100% efficient compression and expansion. A .5 kW CAES system, built from commercial off the shelf components (COTS) to demonstrate the CAES concept, is documented and discussed. This system includes a LabView data acquisition system which was used to record all test results. LabView was also used to develop a complete test bed program that determined real time thermodynamic state properties, component efficiencies, mass flow rates, power outputs and several other performance characteristics of the demonstration system. The LabView program allowed real time efficiency and power optimization of the demonstration system. Results of demonstration system testing are thoroughly discussed. Total system efficiency was very poor; 3.6% electrical conversion efficiency, .040 refrigeration coefficient of performance (COP) and a 5.0% overall efficiency which considers both cooling and electrical storage properties. Several paths for possible future projects involving the demonstration system and CAES are presented.

The technical progress in computerized spatial data acquisition and storage results in the growth of vast spatial databases. Faced with large amounts of increasing spatial data, a terminal user has more difficulty in understanding them without the helpful knowledge from spatial databases. Thus, spatial data mining has been brought under the umbrella of data mining and is attracting more attention. Spatial data mining presents challenges. Differing from usual data, spatial data includes not only positional data and attribute data, but also spatial relationships among spatial events. Further, the instances of spatial events are embedded in a continuous space and share a variety of spatial relationships, so the mining of spatial patterns demands new techniques. In this thesis, several contributions were made. Some new techniques were proposed, i.e., fuzzy co-location mining, CPI-tree (Co-location Pattern Instance Tree), maximal co-location patterns mining, AOI-ags (Attribute-Oriented Induction based on Attributes’ Generalization Sequences), and fuzzy association prediction. Three algorithms were put forward on co-location patterns mining: the fuzzy co-location mining algorithm, the CPI-tree based co-location mining algorithm (CPI-tree algorithm) and the orderclique- based maximal prevalence co-location mining algorithm (order-clique-based algorithm). An attribute-oriented induction algorithm based on attributes’ generalization sequences (AOI-ags algorithm) is further given, which unified the attribute thresholds and the tuple thresholds. On the two real-world databases with time-series data, a fuzzy association prediction algorithm is designed. Also a cell-based spatial object fusion algorithm is proposed. Two fuzzy clustering methods using domain knowledge were proposed: Natural Method and Graph-Based Method, both of which were controlled by a threshold. The threshold was confirmed by polynomial regression. Finally, a prototype system on spatial co-location patterns’ mining was developed, and shows the relative efficiencies of the co-location techniques proposed The techniques presented in the thesis focus on improving the feasibility, usefulness, effectiveness, and scalability of related algorithm. In the design of fuzzy co-location Abstract mining algorithm, a new data structure, the binary partition tree, used to improve the process of fuzzy equivalence partitioning, was proposed. A prefix-based approach to partition the prevalent event set search space into subsets, where each sub-problem can be solved in main-memory, was also presented. The scalability of CPI-tree algorithm is guaranteed since it does not require expensive spatial joins or instance joins for identifying co-location table instances. In the order-clique-based algorithm, the co-location table instances do not need be stored after computing the Pi value of corresponding colocation, which dramatically reduces the executive time and space of mining maximal colocations. Some technologies, for example, partitions, equivalence partition trees, prune optimization strategies and interestingness, were used to improve the efficiency of the AOI-ags algorithm. To implement the fuzzy association prediction algorithm, the “growing window” and the proximity computation pruning were introduced to reduce both I/O and CPU costs in computing the fuzzy semantic proximity between time-series. For new techniques and algorithms, theoretical analysis and experimental results on synthetic data sets and real-world datasets were presented and discussed in the thesis.

Magistro darbe nagrinėjami reklamos samprata, tikslai ir funkcijos. Analizuojami reklamos poveikio metodai ir elementai, reklamos strategija, išskiriami reklamos sudarymo ypatumai, reklamos sprendimų efektyvumo rūšys. Darbe pateikiama reklamos sprendimų efektyvumo vertinimo tyrimo metodika. Tiriamoje darbo dalyje pateikiami AB „Venta“ reklamos sprendimų efektyvumo tyrimo rezultatai bei jų analizė. Atlikto tyrimo rezultatai parodė, kad įmonė dažnai dalyvauja parodose, po kurių įmonės užsakymų kiekis padidėja 20 proc., bei atsiranda naujas klientų ratas. Reklaminė kampanija veiksminga ir efektyvi tada, kai yra rūpestingai parengta ir suplanuota. Sudarant reklaminės kampanijos planą svarbiausias dalykas – tinkamai parinkti reklamos priemones. Renkantis priemones reklaminei informacijai perduoti, būtina išsiaiškinti, kaip vartotojai vertina, tai yra koks yra jų požiūris į atskiras reklamos priemones. Taigi įmonės greta savo atliekamų tyrimų vartotojų pirkimo įpročių ir pan., turėtų įtraukti ir vartotojų požiūrio tyrimus.
Master's work dealt with the concept of advertising, the objectives and functions. Analyzing the impact of advertising methods and elements of advertising strategy, the distinction between advertising features, types of advertising effectiveness solutions. The paper presents solutions of the effectiveness of the advertising research methodology. Concerned in the work presented AB "Venta" advertising solutions of the effectiveness of the results and their analysis. Survey results showed that the company frequently takes part in exhibitions, in which the company's orders increased by 20 percent, and new customers. The advertising campaign is effective and efficient if it is carefully prepared and planned. The conclusion of the advertising campaign plan for the most important thing - to choose the proper means of advertising. The selection of promotional measures for transmission of information is necessary to clarify how users value, that is, what is their approach to individual advertising tools. Thus, in addition to undertaking its own investigations carried out by consumer buying habits and so on. Should be included research and consumer attitudes.

Lo scopo della tesi è stato migliorare la previsione dei consumi energetici di una soluzione meccatronica per poter fornire ai clienti un'informazione più precisa. Viene svolta un'analisi teorica delle perdite ed un'indagine sullo stato dell'arte dei componenti. Successivamente viene sviluppato un codice per generare delle mappe di efficienza per il motore elettrico, in grado di considerare il particolare punto di funzionamento nel diagramma coppia velocità. E' stato condotto un esperimento per validare il suddetto metodo nelle condizioni operative reali. Infine, le informazioni ricavate dalle mappe di efficienza vengono integrate nella selezione ottima dei componenti permettendo una valutazione più affidabile del Total Cost of Ownership.

An exploratory investigation of the electron reconstruction efficiencyat the LHCb is presented. The study is done through simulations ofparticle interaction with the full LHCb detector setup, both by firingsingle particles into the detector and by generating the decay of Bmesons into J/psi K, where the J/psi decays into dileptons. PreviousLHCb analysis of the decay has shown a large yield difference betweenthe number of electron versus muon final states, around a factor offour. The kinematical dependence on the reconstruction efficiency ofthe leptons is studied and found to be non-discriminatory. Theelectronic channel loss of yield is compared to the muonic channel withthe purpose of finding in which reconstruction and selection steps theyield discrepancy factor originates. A total factor of 1.8 is found,which combined with the L0 trigger factor of 2 makes the resultcomparable to the observed factor. A large loss of yield from ageometrical selection, which requires electrons to be in the acceptanceof the electromagnetic calorimeter or in the pre-shower detector,triggers a study of the performance of electrons failing thisrequirement. The performance is determined by looking at how well theparticles are identified, using both LHCb data and simulations. Thefailing electrons are found to perform well, therefore the requirementis considered superfluous and avoiding it would increase the electronfinal state yield with around 14.5%.

Cette thèse contient trois essais expérimentaux étudiant les causes possibles de l’inefficience des marchés des actifs. L’efficacité des marchés financiers est cruciale pour une bonne performance de l’économie dans son ensemble. La recherche en finance comportementale a montré que les investisseurs ne se comportent pas toujours de manière parfaitement rationnelle. Il est donc important de bien comprendre comment les individus créent leurs croyances concernant les décisions financières, ce qui les influence, comment elles affectent les marchés financiers, et donc l’efficacité des marchés.Les croyances individuelles relatives à une décision financière sont influencées par la façon dont les actifs sont déterminés. Le premier essai étudie l’impact du degré d’asymétrie des actifs échangés sur : premièrement, le développement du marché global, deuxièmement, la façon dont les individus perçoivent les actifs risqués en fonction de leurs préférences de risque, et troisièmement, la stabilité de la perception du risque de ces actifs dans le temps. Nos résultats suggèrent que l’asymétrie des actifs n’influence que marginalement le développement du marché, mais a un effet direct sur la perception du risque. Les décisions des agents qui interagissent sur les marchés financiers sont influencées par leurs préférences, leurs traits de personnalité et leurs biais comportementaux. Nous supposons que le profil personnel influe aussi bien sur le comportement individuel sur le marché, tels que l’activité d’échange, l’accumulation de stock et la performance, que sur le développement du marché global, comme la dynamique du prix ou le nombre d’actifs échangés. C’est l’objectif du deuxième essai. Nous constatons que les traits de personnalité sont les meilleurs prédicateurs de comportement du marché, à la fois individuel et global. Le troisième essai examine l’impact des incitations concurrentielles sur l’augmentation des anomalies de marché. Dans ce cas, allonger l’échelle de temps sur laquelle les comparaisons des performances sont basées, contribue-t-il à améliorer l’efficience des marchés financiers ? Nous constatons que le bonus à l’échelle de temps étendue aidera à réduire les anomalies du marché et à améliorer l’efficacité du marché financier
This thesis contains three essays that focus on asset market inefficiency using the experimental method. Financial market efficiency is crucial for good performance of the economy as a whole. Research in behavioral finance has shown that investors do not always behave fully rationally and systematically violate the assumptions of the traditional framework. It is therefore important to fully understand how individuals create their expectations regarding financial decisions, what influences them, how they affect the global market, and therefore financial market efficiency.Individual expectations about a financial decision are influenced by the manner assets are determined. The first essay investigates the impact of skewness of traded assets on first, aggregate market development, second, the way individuals perceive risky assets according to their risk preferences, and third, the stability of the assets’ risk perception in time. Our results suggest that assets’ skewness influences only marginally the asset market development, but directly effects the individual risk perception.Agents interacting in financial markets are not fully rational. Their decisions are influenced by their preferences, personality traits and the degree they are prone to behavioral biases. We suppose that the personal profile influences individual market behavior, such as trading activity, stock accumulation and performance, and also the aggregate market development, such as price dynamic or turnover of traded assets. This is the objective of the second essay. We find that the personality traits are the best predictors of both individual and aggregate market behavior.The third essay examines whether competitive incentives do contribute to the increase of mispricing in financial markets. If they do, does the extended time horizon of performance comparison help to improve the control against excessive risk-taking and therefore improve financial market efficiency. We find that the bonuses with extended time horizon help to diminish mispricing and improve the financial market efficiency

In these past few years the subject of porous metals has gained considerable attention. The area of flow and heat transfer behaviour in porous metals used as regenerators is the focus of this work. A total of 37 porous metal samples have been produced to evaluate their characteristics as regenerators, these include 12 replicated porous metal samples made from commercially pure aluminium using three different NaCl preform particle sizes and two packing methods. The replication method using argon only was improved to become more efficient, tests were done to determine adequate time and temperature for uniform porous metal sample production. In total 4 different protocols (W, X, Y and Z) were developed to produce different levels of porosity (from 61 to 78%) by changing certain variables in the production process. Other porous metal samples were manufactured with the objective of having a wide range of structures and material comparisons; 7 SS304L wire mesh samples, 3 wire felt samples (Al, Cu and SS304L), to evaluate the effect of pore size, 5 packed sphere samples (Al, AISI 52000 chrome steel, Cu, soda glass and SS420) and 10 additive layer manufactured samples (SS316L and Ti6Al4V) to evaluate the effect of material and porosity levels. All the samples were tested on pressure drop and heat transfer capabilities, they were compared with the literature using Reynolds and Stanton numbers, the thermal conductivity was also measured, a characteristic that had to be estimated in previous work due to a lack of an experimental test rig, which was developed during this research. It was found that the best performing ones were the stainless steel wire meshes, the wire felts and the replicated porous metals. Several correlations involving pore size, porosity and material effects were proposed as an aid for designing regenerators obtained from the experimental results. The replicated porous metals have the potential of being used as regenerators if they can be made from high efficiency materials and of a smaller pore size than the ones discussed here, their advantage is that they may be modified to a large range of specifications, being able to replicate the behaviour of other structures.

Energy efficiency of buildings is attracting significant attention from the research community as the world is moving towards sustainable buildings design. Energy efficient approaches are measures or ways to improve the energy performance and energy efficiency of buildings. This study surveyed various energy-efficient approaches for commercial building and identifies Envelope Thermal Transfer Value (ETTV) and Green applications (Living wall, Green facade and Green roof) as most important and effective methods. An in-depth investigation was carried out on these energy-efficient approaches. It has been found that no ETTV model has been developed for sub-tropical climate of Australia. Moreover, existing ETTV equations developed for other countries do not take roof heat gain into consideration. Furthermore, the relationship of ETTV and different Green applications have not been investigated extensively in any literature, and the energy performance of commercial buildings in the presence of Living wall, Green facade and Green roof has not been investigated in the sub-tropical climate of Australia. The study has been conducted in two phases. First, the study develops the new formulation, coefficient and bench mark value of ETTV in the presence of external shading devices. In the new formulation, roof heat gain has been included in the integrated heat gain model made of ETTV. In the 2nd stage, the study presents the relationship of thermal and energy performance of (a) Living wall and ETTV (b) Green facade and ETTV (c) Combination of Living wall, Green facade and ETTV (d) Combination of Living wall, Green Roof and ETTV in new formulations. Finally, the study demonstrates the amount of energy that can be saved annually from different combinations of Green applications, i.e., Living wall, Green facade; combination of Living wall and Green facade; combination of Living wall and Green roof. The estimations are supported by experimental values obtained from extensive experiments of Living walls and Green roofs.

The purpose of this project was to optimise a diesel engine converted to operate on natural gas, to suit the requirements for: low emissions, a high efficiency and sufficient power delivery within the constraints of cogeneration (combined heat and power) systems. Cogeneration Installations seek to improve the efficiency of power generation by utilising waste heat from the prime mover, as well as the production of electricity. Many small scale systems are based on open chamber gas engines, and, to reduce the payback time for the installation, the overall engine efficiency is of prime importance. Stationary engines can be subject to strict standards for emissions, the greatest challenge being presented by the control of NO emissions. The main difficulty is that the highest efficiency operating point of a spark ignition engine is also the point of maximum NO emissions. The extent of this problem was analysed by conducting tests across the entire operating map of the baseline engine at the required speed of 1500 rpm. The solution, in the form of a new high compression ratio combustion system was based on the following: An extensive literature review, the previous Brunel experience with gas engines, an evaluation of the baseline combustion and emissions performance, and the predictions of the Integrated Spark Ignition engine Simulation (ISIS) thermodynamic model. Tests were conducted on the new Fast Bum High Compression Ratio combustion system at compression ratios of 15:1 and 13:1, which demonstrated an extended lean burn capability such that an operating point was identified, that satisfied the conflicting requirements of: low emissions (less than 1g NOx/kWh or 360mg/m3), and a high brake efficiency (above 30%), as well as particular cogeneration criteria. The bmep was mostly above 6 bar. After further tuning and calibration with experimental data, the ISIS model was used to predict the engine power output, efficiency and emissions (NOx and CO) for the compression ratio of 15:1, across the entire operating map for both naturally aspirated and turbocharged configurations. The naturally aspirated results showed good agreement with the results of the experimental 15:1 FBHCR combustion system. The turbocharged engine was simulated with a bmep of 10 bar. The results identified much larger operating areas and all emissions limits were met above a brake efficiency of 36%. The conclusions are, that an open chamber fast bum high compression ratio combustion system can achieve very low emissions, particularly of NOx, and a high efficiency by having the capability of operating with lean enough mixtures. Further improvement in the efficiency is likely if other engine parameters (such as the valve timing) were to be optimised for 1500 rpm. The results from the turbocharged simulation show that turbocharging, whilst restoring the output can also achieve low emissions, and a higher efficiency than a naturally aspirated engine.

Organizations are turning to private clouds due to concerns about security, privacy and administrative control. They are attracted by the flexibility and other advantages of cloud computing but are wary of breaking decades-old institutional practices and procedures. Private Clouds can help to alleviate these concerns by retaining security policies, in-organization ownership and providing increased accountability when compared with public services. This work investigates how it may be possible to develop an energy-aware private cloud system able to adapt workload allocation strategies so that overall energy consumption is reduced without loss of performance or dependability. Current literature focuses on consolidation as a method for improving the energy-efficiency of cloud systems, but if consolidation is undesirable due to the performance penalties, dependability or latency then another approach is required. Given a private cloud in which the machines are constant, with no machines being powered down in response to changing workloads, and a set of virtual machines to run, each with different characteristics and profiles, it is possible to mix the virtual machine placement to reduce energy consumption or improve performance of the VMs. Through a series of experiments this work demonstrates that workload mixes can have an effect on energy consumption and the performance of applications running inside virtual machines. These experiments took the form of measuring the performance and energy usage of applications running inside virtual machines. The arrangement of these virtual machines on their hosts was varied to determine the effect of different workload mixes. The insights from these experiments have been used to create a proof-of- concept custom VM Allocator system for the OpenStack private cloud computing platform. Using CloudMonitor, a lightweight monitoring application to gather data on system performance and energy consumption, the implementation uses a holistic view of the private cloud state to inform workload placement decisions.

Energy efficiency is an important issue as the amount of high rate multimedia wireless communication grows substantially in order to accommodate more users. Over the past 10 years, there has been an unprecedented growth in the wireless information transfer volume and the associated wireless node density. This is especially true in urban areas in which over 50% of the world's population reside. Currently, there are over 7 billion active handsets and 4 million cell-sites globally. Additional infrastructure, in particular Wi-Fi hotspots in urban areas, has reached over 350 nodes per square kilometre. On the other hand, telecommunications operators and vendors are also facing a serious challenge as the total energy consumed by network infrastructure as well as the CO2 emissions resulting from their manufacturing and operation increase significantly. Recently, it has been reported that energy costs can account for as much as half of a mobile carrier's annual operating expenses. Moreover, the environmental and financial consequences would also be disastrous if the aggregate energy consumption of Information and Communication Technologies (ICT) were to follow the predicted growth trajectory. The current combination of the energy consumption of service centres and wireless communication networks accounts for 2–4% of global CO2 emissions and is expected to reach up to 10% in less than 10 years. Therefore it is essential for the research community to investigate state-of-the-art technologies, such as energy-efficient network architecture and protocols, energy-efficient wireless transmission techniques, energy-efficient home networking, and opportunistic spectrum sharing without causing tremendous harmful interference pollution to meet the challenges to improve energy efficiency in communications. As there are many ways to improve energy efficiency in wireless communications illustrated above, this thesis mainly focuses on improving the energy efficiency through the enhancement of network capacity. It starts to examine the relative merits of Long Term Evolution (LTE) femtocell access points (FAP) and 802.11n Wi-Fi radio access technologies (RATs) so as to establish a baseline system-level performance. The results from Monte-Carlo simulations reveal that LTE-femtocells best suit small home networks, providing a high level of spectral- and energy-efficiency. With this result in mind, attention is paid to the next generation of heterogeneous cellular networks, in more detail, in the DownLink (DL) of Orthogonal Frequency Division Multiple Access (OFDMA) based LTE networks. The thesis furthers the study of interference avoidance for a heterogeneous network and applies a novel Radio Resource Management (RRM) algorithm for indoor femtocells. After this, the thesis examines how to create an algorithm that optimises the location of home FAP(s) with respect to the dominant interference. This investigation covers the scenarios of single room single FAP, single room multiple FAPs and multi-room multi-floor multi-FAPs. Finally, special attention is paid to evaluate the system-level performance using a stochastic-geometry theoretical framework which acts as a fundamental basis in the analysis of heterogeneous networks and paves the way for the study of mitigating interference using a frequency-selective-surface (FSS) and the work of the trade-off between interference mitigation via FSS for indoor home network and outdoor-indoor resource sharing by turning on and off the FSS.

The importance of efficiency in the service industry has continued to grow with the increase of services in today’s society. As a result, services must maintain efficient operations in order to achieve positive customer satisfaction and retain their customers. The fear of receiving negative customer satisfaction often results in a firm owner’s reluctance to improve efficiency operations because he or she believes it will hurt sales. This thesis provides a background on restaurant operations efficiency and customer satisfaction and discusses a case study used to explore the effect of efficiency on customer satisfaction. The case study consisted of a time study and customer survey based on a scale called SERVQUAL, which is used as a measure of service quality. The wait times collected during the time study were correlated with the customer survey responses in order to determine strong correlations. Four of the five strong correlations related to the tangibles dimension of service quality, which corresponds to the appearance of the restaurant facilities, equipment, and staff. Due to the determined importance of the tangibles dimension, it can be used as a measure for customer satisfaction. A polynomial regression model was then generated based on the strong correlations. The model indicates that shorter order wait times do not negatively affect customer satisfaction much, but rather, longer order wait times more strongly affect customer satisfaction. Therefore based on the regression model, restaurant owners and managers should focus on reducing the customer order wait time because reducing this time results in higher levels of customer satisfaction. Additionally, these results show that restaurants can choose to increase revenue by improving their efficiency without fear of hurting their customer satisfaction.

Oxygenic photosynthesis is a crucial process for life on earth as it enables plants and algae to convert sunlight into chemical energy, generating molecular oxygen as a byproduct. Light can also be harmful and when in excess can drive to photosystems over‐excitation and production of reactive oxygen species (ROS) with the consequent decrease of the overall photosynthetic efficiency. In a highly dynamic natural environment photosynthetic organisms have evolved sophisticated mechanisms to modulate their efficiency to capture and exploit light. For instance the so called non photochemical quenching of fluorescence (NPQ) acts dissipating excess energy as heat and it’s used as short term response to high light in order to avoid oxidative damages. The carotenoid zeaxanthin belonging to the xanthophyll cycle enhances this thermal dissipation but also has a direct role in the scavenging of ROS generated in the membrane. Acclimation instead is a more complex long term process that acts directly modeling the composition of the photosynthetic apparatus in response to different light intensity, for example through modifications in protein composition. Photoregulation and photoprotection are strongly related also to modulations of flow of excitation energy and electrons across the thylakoid membrane. Indeed the major pathway for the light reactions of photosynthesis, the linear electron flow, can modulate its rate depending on metabolic demand and can be also supported by alternative electron pathway which affect the thylakoid gradient across the membrane and the ATP/NADPH ratio. The general aim of this work is to investigate the different mechanisms modulating photosynthetic efficiency in the microalga Nannochloropsis gaditana in order to increase the limited knowledge about this interesting microalga and exploit it to optimize photosynthetic efficiency in a large-scale cultivation perspective, even through the development of computational models. The spectroscopic tools developed to untangle the complexity of the photosynthetic regulation in Nannochloropsis have been successfully applied to study photosynthesis in other photosynthetic organisms such as, Chlamydomonas reinhardtii, Physcomitrella patens and Koliella antarctica. Nannochloropsis gaditana is an eukaryotic alga of the phylum of heterokonta, originating from a secondary endosymbiotic event. Species of this group have received increasing attention in the scientific community, reflecting their potential application in biofuel production, although the photosynthetic and physiological properties of these organisms remain poorly characterized. Nannochloropsis species have a peculiar photosynthetic apparatus characterized by the presence of chlorophyll a, violaxanthin and vaucheriaxanthin as the most abundant pigments. The regulation of the photosynthetic apparatus in this interesting microalgae has been deeply discussed in Section B. Our study focused firstly on the acclimation response in Nannochloropsis gaditana subjected to prolonged exposition to low and high light. Intense illumination induces a decrease in the chlorophyll content and the antenna size of both Photosystem I and II. Cells grown in high light also show increased photosynthetic electron transport, paralleled by an increased contribution of cyclic electron transport around Photosystem I. Even when exposed to extreme light intensities, Nannochloropsis cells do not activate photo-protection responses, such as NPQ and the xanthophyll cycle in a constitutive way. Conversely, these responses remained available for activation upon additional changes in illumination. These results suggest NPQ and the xanthophyll cycle in Nannochloropsis gaditana play exclusive roles in response to short-term changes in illumination but only play a slight role, if any, in responses to chronic light stress. In order to further explore the short term response mediated by xanthophyll cycle the effect of zeaxanthin accumulation in the photosynthetic apparatus of Nannochloropsis gaditana was investigated revealing some peculiar aspects. Interestingly zeaxanthin molecules are found to be constitutively present in this microalga, even in conditions of very low light in which the xanthophyll cycle is not yet induced. In addition this xanthophyll does not show a specific binding site in the different protein components of the photosynthetic apparatus and, in addition, has a strong effect in the NPQ response. The influence on NPQ seems to be related mostly on de novo synthesis of zeaxanthin while the molecules already present in the photosynthetic apparatus are involved in a transient NPQ active only in the first minute after the dark-light transition. The regulation of the photosynthetic apparatus has been assessed also in N. salina in a growing system more compatible with a large-scale production system, a continuous-flow flat-plate photobioreactor. Interestingly changing the residence time maintaining the same irradiation affects the biomass concentration leading to an acclimation response very similar to that observed for N. gaditana grown in batch system, as previously discussed. These results highlight the importance of the biomass concentration and its connection with light supply as parameter to optimize in order to increase the microalgal culture productivity. The molecular investigation of the mechanisms at the basis of light exploitations in Nannochloropsis is the starting point for the development of computational models that aim to simulate and predict microalgae behavior in order to optimize their productivity in large-scale cultivation systems. Section C deals with the development and widespread application of these models, which integrate chlorophyll fluorescence measurements allowing also the representation of complex mechanisms such as NPQ. Such models prove especially useful in identifying which parameters have the largest impact on productivity, thereby providing a means for enhancing growth through design and operational changes. They can also provide guidance for genetic engineering by identifying those modifications having the largest potential impact on productivity. In Section D the study of photosynthetic processes is expanded to other organisms focusing on the regulation of the photosynthetic electron chain through the employment of several spectroscopic approaches set up during my PhD thesis. In the first work reported we show that the introduction of a mitochondrial mutation in Chlamydomonas reinhardtii mutants depleted in the chloroplastic PGRL1 rescue its photosensitivity in high light. Detailed functional analysis of these cells showed that the mitochondria mutation alters the electron transport reactions increasing alternative electron pathways around PSI at the detriment of PSII-related photosynthesis. This work thus clearly shows how mitochondrial activity play a seminal influence on photosynthesis in algae. The second work presented deals with another important mechanisms to modulate flow of excitation, the Mehler-like reactions mediated by Flavodiiron (FLV) proteins. These proteins were lost during evolution of land plants but are still present in non vascular plants, as the moss Physcomitrella patens, the model organism employed for this study. P. patens mutants depleted in FLV show these proteins are active as an electron sink downstream of Photosystem I. Measurement of electron transport showed that they play a major role particularly in the first seconds after a sudden change in light intensity, when for a few seconds they are the major sink for electrons from PSI. When exposed to fluctuating light FLV mutants showed light sensitivity and PSI photoinhibition, demonstrating their biological role as a safety valve for excess electrons in dynamic light. FLV absence in mutants was, in part, compensated by increased cyclic electron flow, suggesting that their biological role may have been substituted in vascular plants by this other mechanism of alternative electron flow. Finally we analyzed the time course of physiological and morphological responses to different irradiances in Koliella antarctica, a green antarctic microalga isolated from Ross Sea. K. antarctica not only modulates cell morphology and composition of its photosynthetic apparatus on a long-term acclimation, but also shows the ability of a very fast response to light fluctuations. The ability to activate such responses is fundamental for survival in its natural extreme environment.
La fotosintesi ossigenica è un processo fondamentale per la vita sulla terra in quanto consente a piante e alghe di convertire la luce solare in energia chimica generando ossigeno molecolare come sottoprodotto. La luce può anche essere dannosa e quando è in eccesso può portare alla sovreccitazione dei fotosistemi e alla produzione di specie reattive dell'ossigeno (ROS) con un conseguente calo dell’efficienza fotosintetica. In un ambiente naturale estremamente dinamico gli organismi fotosintetici hanno evoluto meccanismi sofisticati in grado di modulare la loro efficienza per catturare e sfruttare al meglio la luce. Per esempio il cosiddetto quenching non fotochimico della fluorescenza (NPQ) agisce dissipando l’energia in eccesso sotto forma di calore ed è utilizzato come sistema di risposta a breve termine agi stress luminosi col fine di evitare danni ossidativi. Il carotenoide zeaxantina appartenente al ciclo delle xantofille partecipa attivamente a questa risposta di dissipazione termica mantenendo però anche un ruolo diretto nello scavenging dei ROS generati nella membrana tilacoidale. L’acclimatazione invece è un processo a lungo termine che agisce direttamente modellando la composizione dell'apparato fotosintetico in risposta all'intensità della luce ad esempio attraverso modifiche nella composizione proteica. I meccanismi di regolazione e protezione indotti dalla luce sono spesso legati anche a modulazioni dei flussi elettronici attraverso la membrana tilacoidale. La via principale per le reazioni alla luce della fotosintesi infatti, il flusso elettronico lineare, è in grado di modulare la sua attività a seconda della richiesta metabolica e può essere sostenuto anche da pathways elettronici alternativi che influenzano il gradiente tilacoidale e il rapporto ATP / NADPH. L'obiettivo generale di questo lavoro è quello di indagare i diversi meccanismi che modulano l'efficienza fotosintetica nella microalga Nannochloropsis gaditana al fine di aumentare la conoscenza ancora limitata di questa microalga e sfruttarla per ottimizzare l'efficienza fotosintetica in un ottica di coltivazione su larga scala, anche attraverso lo sviluppo modelli di calcolo. Gli strumenti spettroscopici sviluppati per districare la complessità dei meccanismi di regolazione della fotosintesi in Nannochloropsis sono stati applicati con successo anche per lo studio di altri organismi fotosintetici quali, Chlamydomonas reinhardtii, Physcomitrella patens e Koliella antarctica. Nannochloropsis gaditana è un'alga eucariotica del phylum heterokonts originata da un evento di endosimbiosi secondaria. Specie di questo gruppo hanno ricevuto una crescente attenzione nella comunità scientifica che riflette la loro potenziale applicazione nella produzione di biocarburanti. Nonostante questo le proprietà fotosintetici e fisiologiche di questi organismi rimangono ancora poco caratterizzate. La specie Nannochloropsis possiede un apparato fotosintetico peculiare contenente come pigmenti più abbondanti clorofilla a, violaxantina e vaucheriaxantina. La regolazione dell'apparato fotosintetico in questa microalga è stato approfondito nella Sezione B. Il nostro studio si è concentrato in primo luogo sulla risposta di acclimatazione in Nannochloropsis gaditana sottoposta a prolungate esposizioni a luce bassa e alta. L’illuminazione intensa induce una diminuzione del contenuto di clorofilla e delle dimensioni della taglia d’antenna del PSI e II. Cellule coltivate in alta luce mostrano anche un aumento del trasporto fotosintetico degli elettroni di pari passo con un maggior contributo da parte del trasporto alternativo ciclico. Anche quando esposte a intensità di luce estreme, le cellule di Nannochloropsis non attivano le risposte di foto-protezione, come ad esempio NPQ e il ciclo delle xantofille, in modo costitutivo. Al contrario, queste risposte rimangono a disposizione per l'attivazione in risposta a ulteriori modifiche dell’ illuminazione. Questi risultati suggeriscono che l’NPQ e il ciclo delle xantofille in Nannochloropsis gaditana giocano un ruolo esclusivo in risposta alle variazioni luminose a breve termine, ma solo un ruolo marginale nelle risposte al stress luminosi cronico. Al fine di esplorare ulteriormente la risposta a breve termine mediata dal ciclo delle xantofille è stato studiato l'effetto dell’ accumulo di zeaxantina nell'apparato fotosintetico di Nannochloropsis gaditana rivelando alcuni aspetti peculiari. E’ interessante notare che le molecole di zeaxantina si trovano ad essere sintetizzate costitutivamente in questa microalga, anche in condizioni di scarsa illuminazione in cui il ciclo delle xantofille non viene indotto. Inoltre questa xantofilla ha dimostrato di non avere un sito di legame specifico nelle diverse componenti proteiche dell’apparato fotosintetico e ha in aggiunta un forte effetto nella risposta di NPQ. L’effetto legato all’ NPQ sembra legato principalmente alla sintesi de novo di zeaxantina mentre le molecole già presenti nel’apparato fotosintetico sono coinvolte in un NPQ transitorio attivo solo nel primo minuto dopo la transizione luce-buio. La regolazione dell'apparato fotosintetico è stata valutata anche in N. salina in un sistema di coltivazione più compatibile con la produzione su larga scala, un fotobioreattore a flusso continuo. È interessante notare che modificare il tempo di permanenza mantenendo la stessa irradiazione influisce sulla concentrazione di biomassa e produce una risposta di acclimatazione molto simile a quella osservata in N. gaditana coltivata in sistema a batch, come precedentemente discusso. Questi risultati evidenziano l'importanza della concentrazione della biomassa e la sua connessione con la luce somministrata come parametro da ottimizzare per aumentare la produttività delle colture microalgali. L'indagine molecolare sui meccanismi alla base dell’utilizzo della luce in Nannochloropsis è il punto di partenza per lo sviluppo di modelli computazionali che mirano a simulare e prevedere il comportamento delle microalghe nell’ottica di ottimizzare la produttività in sistemi di coltivazione su larga scala. La Sezione C tratta dello sviluppo e dell'applicazione di questi modelli, che integrano misure di fluorescenza della clorofilla e consentono anche la rappresentazione di meccanismi complessi come l’NPQ. Tali modelli risultano particolarmente utili per identificare i parametri che hanno il maggiore impatto sulla produttività algale fornendo inoltre una guida per individuare quelle modifiche genetiche che hanno il maggiore potenziale impatto sulla produttività. Nella sezione D lo studio dei processi fotosintetici si espande ad altri organismi focalizzandosi in particolare sui meccanismi di regolazione della catena fotosintetica di trasposto degli elettroni. Questo studio si avvale dell'impiego di diverse tecniche spettroscopiche che ho messo a punto durante la mia tesi di dottorato. Nel primo lavoro riportato viene mostrato come l'introduzione di una mutazione mitocondriale nella microalga Chlamydomonas reinhardtii priva della proteina cloroplastica PGRL1 porti ad un recupero delle performance di crescita in condizioni di alta luce. Analisi fotosintetiche effettuate in queste cellule mutanti ha mostrato che la mutazione mitocondriale altera le reazioni di trasporto degli elettroni aumentando i pathways elettronici alternativi che coinvolgono il PSI e limitando fortemente l’attività del PSII. Questo lavoro dimostra come l'attività mitocondriale abbia un'influenza fondamentale sulla fotosintesi delle microalghe. Il secondo lavoro presentato si occupa di un importante meccanismo volto a modulare il flusso di eccitazione, le reazioni Mehler-like mediate dalle proteine Flavodiiron (FLV). Queste proteine sono state perse durante l'evoluzione delle piante terrestri, ma sono ancora presenti nelle piante non vascolari, come nel muschio Physcomitrella patens, l'organismo modello utilizzato per questo studio. Mutanti di P. patens deprivati della proteina FLV mostrano come quest’ultima abbia un ruolo di sink degli elettroni a valle del PSI. Misure di trasporto elettronico hanno dimostrato che le FLV svolgono un ruolo importante in particolare nei primi secondi dopo una rapida variazione dell'intensità luminosa, quando per alcuni secondi essi agiscono da principale sink degli elettroni provenienti dal PSI. Quando esposti ad una condizione di luce fluttuante i mutanti FLV mostrano fotosensibilità e inibizione del PSI, dimostrando il loro ruolo biologico come valvola di sicurezza in caso di sovrariduzione della catena fotosintetica. L’assenza delle FLV nei mutanti è in parte compensata da un aumento del flusso ciclico degli elettroni, suggerendo che quest’ultimo possa avere sostituito il ruolo biologico delle FLV nelle piante vascolari. Infine abbiamo analizzato l'andamento nel tempo delle risposte fisiologiche e morfologiche a diverse intensità luminose in Koliella antarctica, una microalga verde antartica isolata nel Mare di Ross. K. antarctica modula non solo la morfologia cellulare e il suo apparato fotosintetico tramite una risposta acclimatativa a lungo termine, ma mostra anche la capacità di rispondere rapidamente alle variazioni dell’intensità luminosa. La possibilità di attivare tali risposte è fondamentale per la sopravvivenza nel suo ambiente naturale estremo.

Google Analytics is the most widely used web traffic analytics program in the world with a wide array of functionality which serve several different purposes for its users. However the cost of training employees in the usage of Google Analytics can be expensive and time consuming due to the generality of the software. The purpose of this thesis is to explore an alternative solution to hav- ing employees learn the default Google Analytics interface and thus possibly re- ducing training expenses. A prototype written in the Java programming lan- guage is developed which implements the MVC and facade software patterns for the purpose of making the development process more efficient. It contains a feature for retrieving custom reports from Google Analytics using Google’s Core Reporting API in addition to two web pages are integrated into the proto- type using the Google Embed API. In the result the prototype is used along with the software estimation method COCOMO to make an estimation of the amount of effort required to develop a similar program. This is done by counting the prototype’s source lines of code manually, following the guidelines given by the COCOMO manual, and then implementing the result in the COCOMO estima- tion formula. The count of lines of code for the entire prototype is 567 and the count which considers reused code is 466. The value retrieved from the formula is 1.61±0.14 person months for the estimation of the entire program and 1.31± 0.16 for a program with reused code. The conclusion of the thesis is that the res- ult from the estimation has several weaknesses and further research is necessary in order to improve the accuracy of the result.

This thesis examines the Material Efficiency practices of manufacturing companies in the UK. The study was motivated by the increasing attention given by literature to sustainable strategies in general, with less attention being given to material resources which in turn contributes to the reduced supply of natural resources, persistent solid waste and toxicity. There is also a lack of insight about how the manufacturing industry is coping with pressures to reduce solid waste and better utilise materials as resources. A critical literature review identifies Material Efficiency and related strategies and any issues of implementation. This academic perspective is supported by an exploratory study of Material Efficiency practices using multiple case studies and qualitative data collection and analysis. The participating companies selected were manufacturing companies that practice Material Efficiency and any related strategies. It was found that manufacturers do practice Material Efficiency and related strategies although few of them use the names and constructs found in the literature. Most of the companies do practice the lowest strategy (e.g. Waste Minimisation) in the sustainable manufacturing hierarchy, while most companies struggle with developing the higher strategies such as Resource Efficiency and Eco-efficiency, in part due to measurement complexity. The investigation found a set of attributes in the difficulties, benefits and accelerators that affect manufacturers when implementing Material Efficiency strategies and also studied the factors that motivated the manufacturers to implement and to choose the strategies. It is found from this research that these attributes are interrelated and dependent on each company’s context such as company’s size, type of product, and type of materials used etc. The findings describe real Material Efficiency practices as used inside the UK manufacturing industry, while comparing actual practice to what has been suggested in the literature. The study provides insight into how companies experience and practice Material Efficiency and other related sustainable manufacturing strategies.

Flatness, levelness and plastic shrinkage cracks are three important parameters in the evaluation of the performance of concrete floor surfaces. The rapidly developing concrete floor industry overseas has resulted in a great deal of improvement in the methods for evaluation of surface flatness and levelness. This research encompasses a review of the development and evolution of codes in other countries, an evaluation of the current status in Australia, and reliable evaluation methods for concrete floors. The end result aims to present a comparison of the varying degrees of reliability of the different methods of measurement theoretically and demonstrates the feasibility of specified tolerance through the analysis of field data from actual projects. It also analyses the general assumption that concrete slabs exposed to hot weather conditions soon after casting is prone to plastic shrinkage cracking and its implications. Identifying factors influencing flatness, levelness and plastic shrinkage cracking of concrete slab surface and investigation of their effects are included in this research. Through statistical analysis, significant factors, such as the construction method, environmental conditions and the method of measurement are identified. In addition, sunlight intensity and capacity of concrete bleeding were factors investigated with regard to concrete surface evaporation rate. The monitoring of plastic shrinkage crack initiation and development is an important task in the research of concrete slabs. The research on plastic shrinkage cracking of the slab surface resulted in the development of a digital image analysis method. This method focuses on mapping cracks (MC) and measuring crack width (MCW). Other information such as crack growth over time can also be obtained based on MC and MCW. An accurate method for the measurement of crack width has been developed based on sliced crack image data. Therefore, this method can determine the location of the maximum crack width and measure it with a desired precision.

Road crashes are the main cause of death of young people in the developed world. The factors that cause traffic crashes are numerous; however, most researchers agree that a lack of driving experience is a major contributing factor. Another reason that has been reported for the increased crashes is that novice drivers have not developed the optimum visual search strategies of their more experienced counterparts. Although several training interventions have tried to improve scanning of novice drivers, they have limited success. The aims of this Thesis are to identify some parameters that influence visual search and to develop an efficient training intervention that will improve drivers’ visual skills. In Experiment 1 an image-based questionnaire was used to assess driving instructors’ and novice drivers’ priority ratings to different areas of the driving scene. Results showed that for both groups the opinions regarding visual field prioritisation were highly consistent when compared to chance. Despite the rating consistencies, group differences were found, across all scenarios with “Rear View Mirrors” being the visual field with the most frequent observed group differences. Certain categories (“Road Ahead” and “Mirrors”) were highly ranked across all scenarios, while other categories were more scenario specific. In Experiments 2 & 3 a novel experimental paradigm was used to investigate the interaction bottom-up and top-down influences upon drivers’ visual attention. Analysis showed that participants’ fixation locations had a stronger relationship with where participants clicked (top down) than with saliency peaks (bottom up). In Experiments 4 & 5 the difference in eye movements between driving instructors and learner drivers was examined during simulated driving. Results showed that driving instructors had an increased sampling rate, shorter processing time and broader scanning of the road than learner drivers. Scenario-specific analysis showed that instructors fixated more than learners on side mirrors while learners showed higher visual allocation to the rear view mirror. It was also found that poor visibility conditions and especially rain decrease the effectiveness of drivers’ visual search. Finally in Experiments 6, 7 & 8 we asked how we can improve learner drivers’ visual skills. Results from Experiments 6 & 7 demonstrated that the ability to distinguish between the eye movements of learner drivers and driving instructors improved as the number of objective differences between the two groups increased across specific scenarios. In Experiment 8 a pilot study showed that a scenario specific training intervention can improve certain aspects of learner drivers’ visual skills. The findings of this Thesis have both theoretical and practical implications regarding drivers’ visual search.

Residue number systems (RNS) can efficiently perform addition, subtraction, and multiplication in a parallel and fault tolerant manner. Because of this, they hold significant promise for use in digital signal processing, where high speed arithmetic operators are needed. However, the difficulties in using RNS, such as magnitude comparison between two RNS values, division, and determining overflow or under-flow out of system range, have prevented more widespread use of these systems. This thesis investigates traditional methods to perform comparisons and to propose some new ones. Proposals include residue number system with quotient (RNS-Q), residue number system quotient-on-demand (RNS-QD), and pipelined conversions from traditional RNS to a mixed radix representation. These proposals will be compared with traditional methods with respect to silicon area needed for implementation, speed with which they can be developed, and VLSI techniques utilized to carry out the design.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 102-106).
While the field of desalination has matured for seawater desalination and similar applications, other markets such as the treatment of high salinity feed streams require novel technological innovations. This thesis considers membrane distillation (MD), one of the relatively less studied desalination technologies. The energy efficiency of MD in the sweeping gas (SGMD) configuration along with a multi-tray bubble column dehumidifer is analyzed and compared to other conventional configurations. The single stage SGMD systems studied have relatively low GOR (approximately 2-3) compared to other MD systems. The system mass flow rates and top and bottom temperatures together define optimal operating points of the system. An experimental apparatus designed to analyze scaling and fouling in MD is described in detail along with a discussion of the practical challenges faced and their solutions. Experiments are conducted at various feed temperatures, flow rates and salinities ,and a numerical model of heat and mass transport in MD is validated. MD can treat feed solutions at very high salinities (200 ppt) and still produce extremely pure permeate with salinity less than 0.1 ppt. The experimental apparatus is also used to study the effect of module inclination angle on Air Gap MD flux performance and these results compared with theoretical predictions to determine the optimal orientation of the AGMD apparatus.
by Jaichander Swaminathan.
S.M.

Risk Based Inspection (RBI) is a risk assessment and management tool that addresses an area not completely addressed in other organisational risk management efforts such as Process Hazards Analyses (PHA) or Reliability-Centred Maintenance (RCM) [11]. It complements these efforts to provide a more comprehensive risks assessment associated with equipment operations. RBI yields Inspection and Maintenance Plan for equipment which identifies the actions that should be implemented to provide reliable and safe operation. RBI is a preventive maintenance strategy that combines predicting the expected failure time and condition monitoring as an effort for preventing potential equipment failures. A literature review was conducted to obtain a wide understanding of the RBI field and to capture some of the improvement methods which may have been highlighted by other researchers for baseline purposes. An RBI implementation case study was performed, focusing on the largest power producing utility in Africa, to investigate the efficiency and effectiveness of RBI implementation, thus the results obtained from this case study could have a significant impact in the RBI and Asset Management environment. Efficiency in this study refers to achieving financial benefits, while effectiveness means serving the technical and risk mitigation purpose of a RBI implementation. To evaluate the efficiency of RBI implementation, costs for executing scopes of work prior to RBI implementation were compared to RBI scopes Pre-Outage and Post-Outage scopes execution costs on two power stations that were identified as the most advanced in RBI implementation roll-out plans. Effectiveness was evaluated by assessing the RBI implementation against typical organisation’s objectives through audit findings, interviews, and lessons learnt. Data Analysis was performed as described below: - Cost analysis was performed, comparing the RBI versus Prior RBI maintenance scopes execution costs on the two identified power stations through an excel Model. - Most recurring audit findings were identified through reviewing the audit reports. - A bow-tie risk assessment was performed for the identified eight most recurring audit findings, and probabilities and consequences mitigations were recommended. - Lessons learnt were compiled from the audit findings, bow-tie risk analysis mitigations, interviews results, and RBI sharing sessions. A proposed framework was developed for RBI implementation improvement methods. The results showed that RBI is generally a cost effective process when the prior RBI scope execution cost was compared to RBI scope execution cost. RBI could reduce the maintenance costs through scope optimisation and downtime reduction. The RBI implementation process was found deficient for the specific instances, based on the audit findings and bow-tie risk assessment conducted in the case study. The most significant improvement areas identified included, ensuring that RBI scopes have are uploaded into the Computerised Maintenance Management System and there is only one consolidated final inspection scope submitted to Outage Department and tracked for tasks completion during the outage. This study revealed that the case studied organisation is currently not efficient in implementing RBI, and could benefit significantly if they improve through executing the RBI maintenance inspection scopes as planned. The conducted interviews, recurring audit findings, and lessons learnt analysis demonstrated that the organisation is not effective, as it was successful in meeting only one from a total of six RBI implementation objectives. Extending the inspection frequencies to 72 months and beyond for some low risk components through RBI implementation was the only RBI objective in which the organisation was met successfully.
Dissertation (MEng)--University of Pretoria, 2019.
Eskom
Mechanical and Aeronautical Engineering
MSc
Unrestricted

Non-imaging Fresnel lenses have been playing an important role in improving the efficiency of the solar energy systems. Many researchers and scientists have devoted their research to optimize the design of the Fresnel lenses. Before it can contribute to energy efficiency increase, a Fresnel lens with optimized design will first need to be fabricated with the most cost-effective method as well as the best quality fabrication as possible. If targeted in a commercial market, feasibility of mass production with a minimum fabrication time would also be a consideration. To bring the design optimization of a Fresnel lens from a conceptual theory to a real-life increase in energy efficiency, the lens needs to be fabricated, tested, compared, and analyzed. This research thesis is intended to explore the performance of the lenses with optimized design through experimental investigations. The design optimization was achieved by a previous PhD student at UNT. A total of six lenses fabricated with four different methods along with two purchased lenses were tested with two different approaches. Multiple testing routes were conducted within a 10-month period to observe the effects of material decomposition and degradation on the lens performance. The resulting experimental data has provided a solid base for analyzing the performance of the lenses, in particular, the energy conversion efficiency increase of the solar cell by using each lens. The potential cause of the performance variation can be extracted from the comparison and evaluation.

The synthesis of bicyclobutane and cyclobutene monomers has been studied for the past 30 years. The polymers of these monomers have shown to possess superior properties in comparison to their linear analogs. Current synthetic methods used for the preparation of bicyclobutane and cyclobutene monomers require high temperature, high pressure, a large number of steps, and handling of toxic materials. Generally the synthetic methods employed have given very low yields. Dipolar [2+2]-cycloaddition reactions between alkenes take place spontaneously when one alkene contains strong donor substituents and the other strong acceptor substituents. Our general synthetic scheme involved a [2+2]-cycloaddition to form cyclobutane derivatives containing an acidic proton at C₃ or C₂ and an electron donating substituent at C₁. Following transformation of the donor substituent to a leaving group, bicyclobutanes or cyclobutenes were formed by 1,3- or 1,2-elimination. Phosphite, acetal, and amide as electron-donor substituents in [2+2]-cycloaddition reactions with cyano- or ester-substituted electrophilic alkenes form a variety of cycloadducts.

碩士
國立中興大學
食品暨應用生物科技學系所
102
Freeze concentration is one of the concentrated methods in the food industry. This technology is widely applied to liquid food, including tea, milk, juice, wine and so on. Freeze concentration is a technology to get condensed foods with high quality, which not onlycan retain color and flavor but also nutrients. This study consults Ou’s optimum condition(Ou, 2013) and applies discontinuous progressive freeze concentration with fructose in the vertical glass tube. The aim is to increase the concentration effect by using different stirrer, stirrer sites than changing tubes. On the other hand, we hope to find the optimum conditions in different peristaltic pump rates by setting various size of condenser tubes horizontally. Furthermore, to search out a new method to evaluate the optimum condition in the concentrated condition. The result of concentrating with vertical glass tube shows that tube with large size stirrer (D=6 cm) has the smallest distribution coefficient K. When the stirrer was set away from ice layer with high rotational speed (rpm), the K value would be decrease. Besides, the result of changing tubes in 3.5 hours indicates that the fructose contents can reach to 103% and 114% by high rotational speed (300 rpm) with three times of changing tubes. Concentration in the condenser tube displays that widely contacting area with ice layer helps to obviously shorten the concentrated time. In addition, small size condenser tube cycling with medium rate can keep more fructose in the concentrated solution. On the contrary, condenser tube with large capacity will raise the rate of ice formation and concentrated rate by using high peristaltic pump rate(rpm). Among all the condenser tubes, there is the same concentrated trend in the solution and the ice layer at each concentrated time. In this condenser tube (D/L=2.8 cm/90 cm), the slopes of trend lines are between 0.7522 and 0.8385 when the linearity velocity amid 0.682 and 3.589 mL/sec, and it can be showed the optimum conditions are no difference in the range of linearity velocity. The fructose content, concentrated volume and concentrated time were shown by 3D plot and contour plot.The optimum conditions of concentration could be determined.

碩士
國立臺灣大學
機械工程學研究所
105
In this thesis, in order to fabricate high efficiency thermoelectric (TE) devices, the best TE materials are chosen, some properties related to TE devices made by our laboratory will be analyzed, such as absolute Seebeck coefficient, electrical conductivity and Figure of merit (ZT) can be calculated ultimately. On the other hand, a column-type TE cooler is made to increase contact area and enhance the efficiency of TE devices compared with 2-D thin film TE devices. In the part of performance measurement, DC power supply, temperature controllable plate, TE cooler, thermal couple, equipment Keithley 2400 Source/Meter and equipment Agilent 34972A are used to obtain absolute Seebeck coefficient. Also, the electrical conductivity of 2-D thin film TE devices is evaluated by using above equipment with 4-point probes method. In the part of fabrication of a column-type TE cooler, a silicon dioxide layer is grown on the Si wafer to provide electrical insulation. Bottom connecter and columns are fabricated using magnetron-sputtering-deposited electrical and Bi2.0Te2.7Se0.3, Bi0.4Te3.0Sb1.6 films and patterned using photolithography process. The top connectors are fabricated by dry etching technique and patterned using photolithography process. By the above process, a 60 pairs of column-type TE cooler is fabricated.

Radiation Efficiency improvement of miniaturized microstrip antenna is studied in this thesis. It is shown that, the loss reduction in miniaturized Microstrip Antenna can be achieved through two possible ways. The first is by modifying the materials used for building the antenna, and the second method is by increasing the radiation conductance of the antenna. Material modification at nano/micro scale by replacing conductors with Metallo-Dielectric one dimensional medium for applications in loss reduction is investigated first. It is shown by the Transfer Matrix Method and using simulations that, for a one dimensional medium replacing very thin conductors (less than skin depth) by laminated multilayered conductors reduce losses. However, the improvement does not exceed the case of single conductor which is a few times thicker than skin depth. Secondly, the efficiency improvement of a small H-Shaped patch antenna by using closely coupled stacked parasitic resonators is studied. It is shown that significant improvement in efficiency can be achieved with minimal changes in the foot print, radiation pattern and cross polarization levels of the antenna. The effect of the overall thickness and superstrate dielectric constant on the efficiency improvement is studied parametrically. It is shown that by using 5 radiating resonators and appropriate choice of inter-conductor dielectric constant, for a small increase in thickness of 0.127mm (5mil), the radiation efficiency can be increased from 2.34% to 6.3%. This efficiency improvement can be made very significant from 2.4% to 33%, by increasing the height to 1.27mm (50mil). These translate to a gain improvement of 4dB and 13dB, respectively. This technique is also demonstrated experimentally in H-Shaped antennas with two different levels of miniaturizations.
October 2015

碩士
國立臺灣科技大學
電子工程系
94
The thesis mainly investigates on the high gain, low noise figure and wideband optical fiber amplifiers. The contents are divided into three parts; the first part focuses on high-efficiency Raman fiber amplifier, taking the L-band RFA as an example. By setting up reflection return route (optical circulator) on the structure end, pumping efficiency is improved by double-pass the gain medium. The efficiency of the pump laser used in the structure is 69 % higher than that of the conventional prior work. It also achieves lower noise figure. We also design and simulate the optimum length for the usage of dispersion compensation fiber (DCF) to obtain the greatest output power as 3.6 km and the lowest noise figure as 4 km of DCF. In the second part, we discuss the improved configuration of C+L band erbium doped fiber amplifiers using recycling pump power. All measurements are based on -10 dBm input power with tunable wavelength. There are two kinds of configurations: The first one is the cascaded construction. By setting up an optical circulator as a reflector at the end point to reuse the residual pumping power, the gain and noise figure are 1.76 dB and 0.39 dB improved. When a fiber mirror is used to replace the optical circulator, the gain and noise figure are 1.64 dB and 0.31 dB improved, respectively, compared to the convention one. Another configuration is the parallel construction using a circulator device as the reflector, the gain and noise figure are 1.51 dB and 0.35 dB improved, respectively, after reusing the residual pumping power. When a fiber mirror is used to replace the optical circulator, the gain and noise figure are 1.46 dB and 0.44 dB improved, respectively. In the third part, we fabricate a hybrid fiber amplifier using C-band EDFA and L-band RFA. The concept is to use a single pump laser @1480 nm to supply appropriate power ratio to C and L bands individually. It could gain flattened the C+L band spectra. For the pump laser recycling issue, the gain and noise figure are 19.54 dB and 5.11 dB, respectively, as using an optical circulator. While they are 17.51 dB and 5.04 dB, respectively, as using a fiber mirror.

碩士
國立臺灣大學
生物環境系統工程學研究所
94
The efficiency of thermal, hydraulic, and nuclear power plants can be evaluated by using capacity factor, due to the fact that fuels are continually supplied and properly managed. On the other hand, wind velocity is the fuel of wind turbine. It is never steady and has the cubic relationship with wind energy. Small perturbation in wind speed can result in substantial difference in wind energy. It is thus not adequate to only use capacity factor in the evaluation of wind power plants. Chang et al. (2003) suggests that three wind turbine parameters (capacity factor, wind turbine efficiency and availability factor) have to be considered in analyzing wind energy production. Based on the result of Chang et al. (2003), the main objective of this study is to further investigate the above three wind turbine parameters and their relationship with wind turbine characteristics (such as cut-in velocity, rated velocity, and wind characteristics). Eight different wind turbines at four strong-wind meteorological stations (Wuchi, Tungchitao, Lanyu and Hengchun) in Taiwan are tested. The simulated results show that the slope of the power curve (from cut-in to rated velocity) greatly affects capacity factor of wind turbine. It is concluded that capacity factor can distinguish wind energy production in strong and weak wind periods. However, it cannot be used to determine the suitability of wind turbine installation due to its low recognition of wind turbine characteristics. In contrast, wind turbine efficiency can be applied to demonstrate the optimal wind turbine under different turbine characteristics. Finally, availability factor is classified into un-rated availability factor and rated availability factor, which can clearly express the detailed information of wind turbine operation.

碩士
國立臺灣大學
光電工程學研究所
89
In this thesis, we investigate methods to achieve high efficiency blue light-emitting-diode (LED). The techniques are investigated include oxide-passivation and surface-texturing. Comapred with the unpassivated sample, nearly 200% enhancement in the photoluminescence (PL) response is observed on the sample covered with an oxide layer. By etching the oxide layer, there is an additional enhancement of 140% due to the periodical surface-textured structure. We describe the detail fabricating process of blue LED of InGaN/GaN Multi-Quantum-Well (MQW) structure. The forward turn-on voltage (Vf) of the blue LED is about 7.5V, and the leakage current is improved about 0.7 order over the 0 to -15V reverse bias range. At last, we analyze the reflection coefficient of the surface-textured structure. By proper design of this texture, the reflection coefficient is maintained 5% to 10% over a wide incident angle range between 0°and 20°. Therefore, the external efficiency can be improved by this method.