Dissertations / Theses on the topic 'Channel visualization'

Thesis (M. S. in Mechanical Engineering) Naval Postgraduate School, September 1995.
Thesis advisor(s): Matthew Kelleher. "September 1995." Includes bibliographical references. Also available online.

It has been well reported that the use of multidimensional constellation signals can help to reduce the bit error rate in Additive Gaussian channels by using the hyperspace geometry more efficiently. Similarly, in fading channels, dimensionality provides an inherent signal space diversity (distinct components between two constellations points), so the amplitude degradation of the signal are combated significantly better. Moreover, the set of n-dimensional signals also provides great compatibility with various Trellis Coded modulation schemes: N-dimensional signaling joined with a convolutional encoder uses fewer redundant bits for each 2D signaling interval, and increases intra-subset minimum squared Euclidean distance (MSED) to approach the ultimate capacity limit predicted by Shannon's theory. The multidimensional signals perform better for the same complexity than two-dimensional schemes. The inherent constellation expansion penalty factor paid for using classical mapping structures can be decreased by enlarging the constellation's dimension. In this thesis, a multidimensional signal set construction paradigm that completely avoids the constellation expansion penalty is used in Band-limited channels and in fading channels. As such, theoretical work on performance analysis and computer simulations for Quadrature-Quadrature Phase Shift Keying (Q2PSK), Constant Envelope (CE) Q2PSK, and trellis-coded 16D CEQ2PSK in ideal band-limited channels of various bandwidths is presented along with a novel discussion on visualization techniques for 4D Quadrature-Quadrature Phase Shift Keying (Q2PSK), Saha's Constant Envelope (CE) Q2PSK, and Cartwright's CEQ2PSK in ideal band-limited channels. Furthermore, a metric designed to be used in fading channels, with Hamming Distance (HD) as a primary concern and Euclidean distance (ED) as secondary is also introduced. Simulation results show that the 16D TCM CEQ2PSK system performs well in channels with AWGN and fading, even with the simplest convolutional encoder tested; achievable coding gains using 16-D CEQ2PSK Expanded TCM schemes under various conditions are finally reported.

Current cabling systems in cars are about to be, completely or partially, replaced by a cabling technology called flexible flat cables, FFCs. This new technology requires tools that can assist engineers in the design process of the cable layouts. The aim of this thesis is to develop a software demonstrator of a concept tool for this purpose.

The task is divided into three problem areas. Topology modeling, optimization and visualization. An editor is to be implemented which handles creation and modification of topologies which represents FFC harnesses. The optimization is performed using global and local routing. The global routing handles optimization on topology level, defining net paths in the topology. Local routing handles the exact net placement on each bus cable. Finally, the local routing solutions should be graphically presented to the user.

The topology modeling requirement was implemented as a graph layouteditor. Global routing is performed using graph search techniques and local routing is based on VLSI channel routing methods. Visualization is implemented for the local routing solutions using the SVG format.

The developed application handles most of the requirements. The editor has support for an XML netlist which is used for specifying connectors and nets used in the topology. Global routing and local routing can be performed on the topology. Prerouting of nets can be performed on both global and local level. Support for assigning specific cables, from a library, to bus cables is possible.

In this thesis I investigate characteristics of turbulent flow in a channel where one of the walls has riblets, superhydrophobic microribs, or a hybrid surface with traditional riblets built on a superhydrophobic microrib surface. PIV measurements are used to find the velocity profile, the turbulent statistics, and shear stress profile in the rectangular channel with one wall having a structured test surface. Both riblets and superhydrophobic surfaces can each provide a reduction in the wall shear stress in a turbulent channel flow. Characterizing the features of the flow using particle image velocimetry (PIV) is the focus of this research. Superhydrophobicity results from the combination of a hydrophobic coating applied to a surface with microrib structures, resulting in a very low surface energy, such that the fluid does not penetrate in between the structures. The micro-rib structures are aligned in the streamwise flow direction. The riblets are larger than the micro-rib structure by an order of magnitude and protrude into the flow. All the test surfaces were produced on silicon wafers using photolithographic techniques. Pressure in the channel is maintained below the Laplace pressure for all testing, creating sustainable air pockets between the microribs. Velocity profiles, turbulent statistics, shear stress profiles, and friction factors are presented. Measurements were acquired for Reynolds numbers ranging from 4.5x10^3 to 2.0x10^4. Modest drag reductions were observed for the riblet surfaces. Substantial drag increase occurred over the superhydrophobic surfaces. The hybrid surfaces showed the greatest drag reduction. Turbulence production was strongly reduced during riblet and hybrid tests.

" More and more researchers are focusing on the management, querying and pattern mining of streaming data. The visualization of streaming data, however, is still a very new topic. Streaming data is very similar to time-series data since each datapoint has a time dimension. Although the latter has been well studied in the area of information visualization, a key characteristic of streaming data, unbounded and large-scale input, is rarely investigated. Moreover, most techniques for visualizing time-series data focus on univariate data and seldom convey multidimensional relationships, which is an important requirement in many application areas. Therefore, it is necessary to develop appropriate techniques for streaming data instead of directly applying time-series visualization techniques to it. As one of the main contributions of this dissertation, I introduce a user-driven approach for the visual analytics of multivariate data streams based on effective visualizations via a combination of windowing and sampling strategies. To help users identify and track how data patterns change over time, not only the current sliding window content but also abstractions of past data in which users are interested are displayed. Sampling is applied within each single time window to help reduce visual clutter as well as preserve data patterns. Sampling ratios scheduled for different windows reflect the degree of user interest in the content. A degree of interest (DOI) function is used to represent a user's interest in different windows of the data. Users can apply two types of pre-defined DOI functions, namely RC (recent change) and PP (periodic phenomena) functions. The developed tool also allows users to interactively adjust DOI functions, in a manner similar to transfer functions in volume visualization, to enable a trial-and-error exploration process. In order to visually convey the change of multidimensional correlations, four layout strategies were designed. User studies showed that three of these are effective techniques for conveying data pattern changes compared to traditional time-series data visualization techniques. Based on this evaluation, a guide for the selection of appropriate layout strategies was derived, considering the characteristics of the targeted datasets and data analysis tasks. Case studies were used to show the effectiveness of DOI functions and the various visualization techniques. A second contribution of this dissertation is a data-driven framework to merge and thus condense time windows having small or no changes and distort the time axis. Only significant changes are shown to users. Pattern vectors are introduced as a compact format for representing the discovered data model. Three views, juxtaposed views, pattern vector views, and pattern change views, were developed for conveying data pattern changes. The first shows more details of the data but needs more canvas space; the last two need much less canvas space via conveying only the pattern parameters, but lose many data details. The experiments showed that the proposed merge algorithms preserves more change information than an intuitive pattern-blind averaging. A user study was also conducted to confirm that the proposed techniques can help users find pattern changes more quickly than via a non-distorted time axis. A third contribution of this dissertation is the history views with related interaction techniques were developed to work under two modes: non-merge and merge. In the former mode, the framework can use natural hierarchical time units or one defined by domain experts to represent timelines. This can help users navigate across long time periods. Grid or virtual calendar views were designed to provide a compact overview for the history data. In addition, MDS pattern starfields, distance maps, and pattern brushes were developed to enable users to quickly investigate the degree of pattern similarity among different time periods. For the merge mode, merge algorithms were applied to selected time windows to generate a merge-based hierarchy. The contiguous time windows having similar patterns are merged first. Users can choose different levels of merging with the tradeoff between more details in the data and less visual clutter in the visualizations. The usability evaluation demonstrated that most participants could understand the concepts of the history views correctly and finished assigned tasks with a high accuracy and relatively fast response time. "

This study examined the effectiveness of information about, and/or practice with, visualization in increasing: self-understanding, belief in one's ability to effect self change, positive themes in ongoing imagery, and internality of locus of control. A sample of 19 women and 11 men, ranging in age from 18 to 50 years, were divided into four groups which each received different amounts of information about, or practice with, visualization. All groups were tested before and after treatment on four measures, and the three experimental groups also completed a posttest-only measure. The measures used were the Personal Response Questionnaire (developed by the author), subscales from the Imaginal Processes Inventory, the Spheres of Control test, the Questionnaire on Imagery Control, and the Questionnaire Upon Mental Imagery. Results indicated that members of the experimental groups believed that visualization could contribute significantly to self-understanding, felt differently about themselves as a result of learning about visualization, felt it would be useful for personal development, and felt they would use it in their own future self-development. Vividness of imagery increased from pretest to posttest for those groups with most information about, and practice with, visualization. Increased internality on the sociopolitical control subscale of the Spheres of Control test was also found for all groups on the posttest. None of the other predicted effects were found to have occurred at a significant level. The failure to achieve the anticipated results was attributed partially to the short period of training and practice allocated, to the small number of subjects, and also to the lack of appropriate and sufficiently sensitive assessment measures.
Arts, Faculty of
Psychology, Department of
Graduate

Thesis: S.M., Harvard-MIT Program in Health Sciences and Technology, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 36-39).
The need for new antibiotics is great as bacterial strains with single and multiple drug resistance have continued to grow more prevalent since the 1980's. At the same time, the rate of approval of new antibiotics has dropped precipitously. Existing antibiotics commonly target the bacterial ribosome. A or cell wall synthetic pathways: two targets that are essential for bacterial survival. However, another option is to target a pathway which is more intimately connected to bacterial pathogenesis: protein secretion. In bacteria, most secreted polypeptides are pushed across the membrane, via the SecYEG channel, by the SecA ATPase. Relatively little is understood of how SecA couples ATP hydrolysis to polypeptide translocation. X-ray crystallography and many biochemical studies support a model in which the two-helix finger (2HF) of SecA pushes the polypeptide through the SecYEG channel, however some evidence is contradictory. We aim to directly measure conformational changes of the 2HF by utilizing single-molecule Fbrster resonance energy transfer (smFRET). Directly measuring conformational changes in an ATPase will also provide further insight into the guiding principles of ATPase function. First, we will build a smFRET microscope and assemble a software package to analyze the data it collects. We will then validate these tools by reproducing results currently in the literature from Holden et al. and McKinney et al.. Next, we will assess the potential limitations of current tools for smFRET data analysis, especially as applied to ATPases. We will propose a new approach that may be useful in these systems. Finally, we will use the smFRET microscope to measure ATP-dependent conformational dynamics of the 2HF. This evidence will help differentiate between three proposed models: the 2HF (1) is not directly involved in polypeptide translocation, (2) moves unidirectionally, directly driving translocation, or (3) moves back and forth but in a way that is coordinated by ATP hydrolysis with progress capture elsewhere in SecA.
by Jacob D. Sargent.
S.M.

Proton fluxes through plasma membranes are essential for regulating intracellular and extracellular pH and mediating co-transport of metabolites and ions. Although conventional electrical measurements are highly sensitive and precise for proton current detection, they provide limited specificity and spatial information. My thesis focuses on developing optical approaches to visualize proton fluxes from ion channels and transporters. It has been demonstrated that channel-mediated acid extrusion causes proton depletion at the inner surface of the plasma membrane. Yet, proton dynamics at the extracellular microenvironment are still unclear. In Chapter II, we developed an optical approach to directly measure pH change in this nanodomain by covalently attaching small-molecule, fluorescent proton sensors to the cell’s glycocalyx using glyco-engineering and copper free ‘click’ chemistry. The extracellularly facing sensors enable real-time detection of proton accumulation and depletion at the plasma membrane, providing an indirect readout of channel and transporter activity that correlated with whole-cell proton current. Moreover, the proton wavefront emanating from one cell was readily visible as it crossed over nearby cells. The transport of monocarboxylates, such as lactate and pyruvate is critical for energy metabolism and is mainly mediated by proton-coupled monocarboxylate transporters (MCT1-MCT4). Although pH electrodes and intracellular fluorescent pH sensors have been widely used for measuring the transport of proton-coupled MCTs, they are unable to monitor the subcellular activities and may underestimate the transport rate due to cell’s volume and intracellular buffering. In Chapter III, we used the Chapter II approach to visualize proton-coupled transport by MCT1-transfected HEK293T cells and observed proton depletion followed by a recovery upon extracellular perfusion of L-lactate or pyruvate. In addition, we identified a putative MCT, CG11665/Hrm that is essential for autophagy during cell death in Drosophila. The results demonstrate that Hrm is a bona fide proton-coupled monocarboxylate transporter that transports pyruvate faster than lactate. Although the approach developed in Chapter II enables visualization of proton fluxes from ion channels and transporters, it’s not applicable in some cell types which cannot incorporate unnatural sialic acid precursors into their glycocalyx, such as INS-1 cells and cardiomyocytes. To address this, in Chapter IV we developed a pH-sensitive, fluorescent WGA conjugate, WGA-pHRho that binds to endogenous glycocalyx. Compared to the results in Chapter II and III, cell surface-attached WGA-pHRho has similar fluorescent signals in response to proton fluxes from proton channel Hv1, omega mutant Shaker-IR R362H and MCT1. With WGA-pHRho, we were able to label the plasma membrane of INS-cells and cardiomyocytes and visualized the transport activity of MCT1 in these cells. Taken together, these findings provide news insights into proton dynamics at the extracellular environment and provide new optical tools to visualize proton fluxes from ion channels and transporters. Moreover, the modularity of the approaches makes them adaptable to study any transport events at the plasma membrane in cells, tissues, and organisms.

Visualization is a lean tool and in order to strive to become a lean company applying the lean philosophy in all these parts of the organization is necessary. A company that does not understand the philosophy and culture behind lean production, even though applying lean tools, is not a lean business and has a long way to production excellence.

 

Implementing and becoming a visual organization means change which includes the organizational culture, collective attitude and beliefs. The difference between success and failure is about the ability to provide knowledge, information and to create prerequisites for participation and engagement at all levels in the organization with a clear and direct leadership.

 

In many companies communication is lacking sufficient and official channels, and the inadequacy in the information systems are usually due to functional thinking and strict boarders at all levels in an organization. New ways of communication are the result of process orientation, demanding new prerequisites for information systems which companies needs to develop and thus become more visual. Knowledge and information needs to become more accessible and objective in order for decision to be taken based on facts not be the result of interpretations of reality. Visualization enables people to see and develop an objective and common reality. It further contributes to the organizations ability for improvement and aligns the employees to fulfill the overall business objectives and strategies.

 

The Company in this case that wants to be anonymous will further be called Company X. Company X objective is to develop a visual communication system to increase the information sharing and flow throughout the organization. However, this is not an easy task and many companies lack sufficient prerequisites to carry out a successful implementation. The research result at Company X has in this study shown weaknesses in core areas as in clear and direct leadership, vision and strategy development and communication as well as a low level of knowledge transformation at all levels in the organization in order to create engagement for the change process which an implemetion of this kind is.

 

Visualisering är ett lean verktyg och i sträva att bli ett lean företag måste lean filosofin tillämpas i alla delar av organisationen, vilket är en nödvändighet. Ett företag som inte förstår filosofin och kulturen bakom lean produktion, trots att man tillämpar lean verktyg, är inte ett lean företag och har en lång väg från optimering av produktion. Förutsättningarna att bli en visuell organisation innebär förändringar som omfattar organisations kultur, kollektiva attityder och föreställningar. Skillnaden mellan framgång och misslyckande handlar om förmågan att ge kunskap, information och att skapa förutsättningar för delaktighet och engagemang på alla nivåer i organisationen, detta genom ett tydligt och direkt ledarskap.

 

Kommunikation på många företag saknar ofta tillräckliga och officiella kanaler och bristen på information beror många gånger på funktionstänkande och strikta gränser, på alla nivåer i organisationen. Nya sätt att kommunicera är resultatet av processorientering vilket krävs för att företag ska kunna skapa förutsättningar för informationssystem och bli mer visuella. Kunskap och information måste bli mer tillgängligt och objektivt för att beslut som är baserade på fakta och inte på tolkningar av verkligheten ska kunna fattas. Visualiseringen möjliggör för människor att se och utveckla en objektiv och gemensam verklighet. Detta bidrar till organisationers möjlighet till förbättringar och möjlighet för de anställda att uppfylla de övergripande affärsmålen och strategierna för organisationen.

 

Det studerade företaget som valt att vara anonymt kommer hädanefter kallas för Företag X. Företag X målsättning är att utveckla ett visuellt kommunikationssystem i syfte att öka utbytet av information och dess flöden . Men detta är inte en lätt uppgift och många företag har inte tillräckliga förutsättningar för att kunna genomföra en framgångsrik implementering. Resultaten från studien på företaget X visar på svagheter inom kärnområden som ett klart och tydligt ledarskap, utvecklandet och kommunikationen av vision och strategier samt en låg nivå rörande kunskapsspridandet på alla nivåer i organisationen för att skapa engagemang för förändrings process som en implementering av detta slag innebär.

This dissertation expands upon the definition of eco-visualization artwork. EV was originally defined in 2006 by Tiffany Holmes as a way to display the real time consumption statistics of key environmental resources for the goal of promoting ecological literacy. I assert that the final forms of EV artworks are not necessarily dependent on technology, and can differ in terms of media used, in that they can be sculptural, video-based, or static two-dimensional forms that communicate interpreted environmental information. There are two main categories of EV: one that is predominantly screen-based and another that employs a variety of modes of representation to visualize environmental information. EVs are political acts, situated in a charged climate of rising awareness, operating within the context of environmentalism and sustainability. I discuss a variety of EV works within the frame of ecopsychology, including EcoArtTech’s Eclipse and Keith Deverell’s Building Run; Andrea Polli’s Cloud Car and Particle Falls; Nathalie Miebach’s series, The Sandy Rides; and Natalie Jeremijenko’s Mussel Choir. The range of EV works provided models for my creative project, Sculpting Corn Production, and a foundation from which I developed a creative methodology. Working to defeat my experience of solastalgia, Sculpting Corn Production is a series of discrete paper sculptures focusing on American industrial corn farming. This EV also functions as a way for me to understand our devastated monoculture landscapes and the politics, economics, and related areas of ecology of our food production.

Background: Organizations today are having to initiate the necessary changes as they are pressured to keep up with market environments that often yield unpredictable and complex events. When initiating, and more importantly, attempting to implement these changes, the theory states that 70% of these efforts fail. One of the reasons behind this high rate of failure is the ineffective internal communication during strategic change, which results in misunderstandings and perhaps even resistance among employees. Here, building on previous research, it is argued that visual management can play an important role. However, the current theory lacks empirical research that investigates or examines the current usage of visualizations as a strategic tool during change, as the majority focuses on providing literature reviews or theoretical frameworks. Research question: To what extend do organizations use visualizations within the process of organizational change? Purpose: The purpose of this dissertation is to get a better understanding of the usage of visualizations as a strategic tool during the process of organizational change. Method: In order to fulfil the purpose of the thesis and to be able to explore the research question, a quantitative research design was chosen. The data for this thesis was collected through a web-based questionnaire among organizations situated in The Netherlands. A specification was made towards organizational structure whereas the retail sector can be characterised as having multiple hierarchical levels. The survey consisted of three parts each dedicated to a sub-question relating to the main research question. In total, 282 respondents participated in the research. Theoretical framework: An overview of the current literature is provided starting with describing the topic of change, where several aspects such as the factors supporting and hampering change and the process of strategic change are discussed. In addition, a specification is made towards communication, where especially internal communication during change is highlighted. The final component in this theoretical framework is visualizations, which is discussed by summarizing what the current theory states regarding characteristics, types, strategic usage and the field of visual management. All of this through a strategic scope and within the setting of organizational or strategic change. Findings: In this dissertation, it was discovered that a very low amount of organizations perceives their change efforts to be successful. This may be due to things not always going according to plan, where interestingly, a high number of organizations did state that plans are created during strategic or organizational change. Secondly, the data showed how organizations are already showing a significant use of visualizations as a strategic tool during change. However, the more ‘complex’ visualizations scored noticeably lower on usage and frequency. Lastly, within the findings of this thesis it became apparent that organizations perceive the usage of visualizations during change to be very positive. Especially high numbers were found on how using visualizations can lead to employees better understanding why the changes are needed.

A gap of knowledge exists between the latest climate change research and the general public. The goal of this thesis is to bridge that gap by making the information more accessible and easier to understand. A proof-of-concept model is created with the goal to visualize carbon emission data, namely size relations between countries, source of emissions per country and the current state of carbon emissions compared to a stated goal (the Paris Agreement), and give the user options to reach said goal by manipulating percentages of renewable energy, electric vehicles, and industry, on a global or local scale.User studies are then performed with members of the target group (students age 13-15) to test whether these visualizations are intuitive and accurately communicates the visualized data. The studies are effective and the goal of the visualization is reached.
Det finns en informationslucka mellan den nyaste forskningen inom klimatförändring och den allmänna befolkningen. Målet med denna tes är att minska luckan genom att göra den informationen lättare att förstå. En proof-of-concept modell skapas med målet att visualisera kolutsläppsdata, specifikt storleksförhållanden mellan olika länder, utsläppskällor för olika länder, samt det nuvarande läget av kolutsläpp jämfört med ett framtida mål (Paris Agreement), och att ge användaren alternativ för att uppnå det målet genom att manipulera procenten av förnyelsebar energi, elektriska fordon och industri, antingen globalt eller lokalt.Användarstudier utförs därefter med medlemmar av målgruppen (studenter 13-15 år gamla) för att se om visualiseringen är intuitiv och kommunicerar korrekt information om den visualiserade datan. Användarstudien är effektiv och visar att målet för visualiseringen är uppnått.

The following study investigates how recent games (2014 - 2018) visualize health and health changes, with a focus on the player character’s health, the player character taking damage and the graphical user interface (GUI). 50 games were coded via gameplay videos on YouTube and then analysed. The codes were then grouped together based on patterns and theoretical grounding. These groups were then examined with other studies and game design practices.
Följande studie ämnar att undersöka hur spel från senaste tiden (2014 - 2018) visualiserar hälsa och hälsoförändringar, med ett fokus på spelarkaraktärens hälsa, när spelarkaraktären tar skada och GUI. 50 spel kodades via s.k. “gameplay” videor på YouTube och har sedan blivit analyserade. Koderna var sedan grupperade baserad på mönster och teori. Dessa grupper var sedan undersökta med andra studier och speldesign sedvänjor.

The context of this thesis is the numerical simulation of turbulent flows at moderate Reynolds numbers and the improvement of the capabilities of an in-house 3D unsteady and incompressible flow solver called SFELES to simulate such flows.

In addition to this abstract, this thesis includes five other chapters.

The second chapter of this thesis presents the numerical methods implemented in the two CFD solvers used as part of this work, namely SFELES and PHASTA.

The third chapter concentrates on the implementation of a new library called FlexMG. This library allows the use of various types of iterative solvers preconditioned by algebraic multigrid methods, which require much less memory to solve linear systems than a direct sparse LU solver available in SFELES. Multigrid is an iterative procedure that relies on a series of increasingly coarser approximations of the original 'fine' problem. The underlying concept is the following: low wavenumber errors on fine grids become high wavenumber errors on coarser levels, which can be effectively removed by applying fixed-point methods on coarser levels.

Two families of algebraic multigrid preconditioners have been implemented in FlexMG, namely smooth aggregation-type and non-nested finite element-type. Unlike pure gridless multigrid, both of these families use the information contained in the initial fine mesh. A hierarchy of coarse meshes is also needed for the non-nested finite element-type multigrid so that our approaches can be considered as hybrid. Our aggregation-type multigrid is smoothed with either a constant or a linear least square fitting function, whereas the non-nested finite element-type multigrid is already smooth by construction. All these multigrid preconditioners are tested as stand-alone solvers or coupled with a GMRES (Generalized Minimal RESidual) method. After analyzing the accuracy of the solutions obtained with our solvers on a typical test case in fluid mechanics (unsteady flow past a circular cylinder at low Reynolds number), their performance in terms of convergence rate, computational speed and memory consumption is compared with the performance of a direct sparse LU solver as a reference. Finally, the importance of using smooth interpolation operators is also underlined in this work.

The fourth chapter is devoted to the study of subgrid scale models for the large eddy simulation (LES) of turbulent flows.

It is well known that turbulence features a cascade process by which kinetic energy is transferred from the large turbulent scales to the smaller ones. Below a certain size, the smallest structures are dissipated into heat because of the effect of the viscous term in the Navier-Stokes equations.

In the classical formulation of LES models, all the resolved scales are used to model the contribution of the unresolved scales. However, most of the energy exchanges between scales are local, which means that the energy of the unresolved scales derives mainly from the energy of the small resolved scales.

In this fourth chapter, constant-coefficient-based Smagorinsky and WALE models are considered under different formulations. This includes a classical version of both the Smagorinsky and WALE models and several scale-separation formulations, where the resolved velocity field is filtered in order to separate the small turbulent scales from the large ones. From this separation of turbulent scales, the strain rate tensor and/or the eddy viscosity of the subgrid scale model is computed from the small resolved scales only. One important advantage of these scale-separation models is that the dissipation they introduce through their subgrid scale stress tensor is better controlled compared to their classical version, where all the scales are taken into account without any filtering. More precisely, the filtering operator (based on a top hat filter in this work) allows the decomposition u' = u - ubar, where u is the resolved velocity field (large and small resolved scales), ubar is the filtered velocity field (large resolved scales) and u' is the small resolved scales field.

At last, two variational multiscale (VMS) methods are also considered.

The philosophy of the variational multiscale methods differs significantly from the philosophy of the scale-separation models. Concretely, the discrete Navier-Stokes equations have to be projected into two disjoint spaces so that a set of equations characterizes the evolution of the large resolved scales of the flow, whereas another set governs the small resolved scales.

Once the Navier-Stokes equations have been projected into these two spaces associated with the large and small scales respectively, the variational multiscale method consists in adding an eddy viscosity model to the small scales equations only, leaving the large scales equations unchanged. This projection is obvious in the case of a full spectral discretization of the Navier-Stokes equations, where the evolution of the large and small scales is governed by the equations associated with the low and high wavenumber modes respectively. This projection is more complex to achieve in the context of a finite element discretization.

For that purpose, two variational multiscale concepts are examined in this work.

The first projector is based on the construction of aggregates, whereas the second projector relies on the implementation of hierarchical linear basis functions.

In order to gain some experience in the field of LES modeling, some of the above-mentioned models were implemented first in another code called PHASTA and presented along with SFELES in the second chapter.

Finally, the relevance of our models is assessed with the large eddy simulation of a fully developed turbulent channel flow at a low Reynolds number under statistical equilibrium. In addition to the analysis of the mean eddy viscosity computed for all our LES models, comparisons in terms of shear stress, root mean square velocity fluctuation and mean velocity are performed with a fully resolved direct numerical simulation as a reference.

The fifth chapter of the thesis focuses on the numerical simulation of the 3D turbulent flow over a re-entry Apollo-type capsule at low speed with SFELES. The Reynolds number based on the heat shield is set to Re=10^4 and the angle of attack is set to 180º, that is the heat shield facing the free stream. Only the final stage of the flight is considered in this work, before the splashdown or the landing, so that the incompressibility hypothesis in SFELES is still valid.

Two LES models are considered in this chapter, namely a classical and a scale-separation version of the WALE model. Although the capsule geometry is axisymmetric, the flow field in its wake is not and induces unsteady forces and moments acting on the capsule. The characterization of the phenomena occurring in the wake of the capsule and the determination of their main frequencies are essential to ensure the static and dynamic stability during the final stage of the flight.

Visualizations by means of 3D isosurfaces and 2D slices of the Q-criterion and the vorticity field confirm the presence of a large meandering recirculation zone characterized by a low Strouhal number, that is St≈0.15.

Due to the detachment of the flow at the shoulder of the capsule, a resulting annular shear layer appears. This shear layer is then affected by some Kelvin-Helmholtz instabilities and ends up rolling up, leading to the formation of vortex rings characterized by a high frequency. This vortex shedding depends on the Reynolds number so that a Strouhal number St≈3 is detected at Re=10^4.

Finally, the analysis of the force and moment coefficients reveals the existence of a lateral force perpendicular to the streamwise direction in the case of the scale-separation WALE model, which suggests that the wake of the capsule may have some

preferential orientations during the vortex shedding. In the case of the classical version of the WALE model, no lateral force has been observed so far so that the mean flow is thought to be still axisymmetric after 100 units of non-dimensional physical time.

Finally, the last chapter of this work recalls the main conclusions drawn from the previous chapters.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Software development is an endless problem-solving activity and programmers regularly use online media channels to ask each other for advice. In particular, socially enabled media channels like the question & answer website Stack Overflow changed how programmers communicate and coordinate, and how they produce and consume content on the Web. Nowadays, a vast body of software development knowledge is documented in form of code examples. But acquiring the knowledge by reading code and logically reason about how they work makes non-trivial examples hard to understand. The aim of this work is to develop visual enhancements that support programmers in the knowledge exchange with code examples. Through a design science research approach using interaction design methods visualizations were developed and evaluated that allow programmers to see the execution and simultaneously inspect the state in order to gain a better understanding of how the underlying system of the code example works. Professional programmers participated in a workshop and found the visualizations to be helpful in the comprehension process.

Mobile augmented reality has become an influential tool for digital content representation and visualization of media content in terms of enhancing users' experience and improving the adaptability and usability of typical augmented reality applications, such as in e-commerce shopping, virtual museum, or digital heritage scenarios. This research proposes a new Service Oriented Mobile AR Architecture called SOMARA, which includes a novel mobile AR client application. SOMARA takes advantage the ability to integrate third party content through service orientation. The SOMARA architecture enhances traditional standalone mobile AR applications with embedded media content by uniquely integrating a web service framework into an augmented reality client application to create more efficient and flexible mobile augmented reality applications that efficiently supports novel media content acquisition and visualization through appropriate access parameters. The proposed architecture requires access to media content through specific media content service providers, e.g. a museum commissioning an augmented reality based museum interactive — predetermined media content, or any third party with their own service APIs, e.g. the Victoria and Albert Museum API — related external media content. This approach allows relevant third party media content to be ‘mashed' via their public API with museums' augmented reality interactive's ‘embedded' media content in the SOMARA mobile AR client. In this way novel mobile AR interactive applications, such as a museum augmented reality interactive, can be created based on particular museum environment scenarios that integrate a museum visitor's experience with the interactive's cultural objects. Such experiences based on a SOMARA type museum augmented reality interactive can also be saved allowing visitors to take home their museum experience. SOMARA thus allows museum interactive experiences based on visualization of museums and third party media content physically located in the museum to be migrated to the visitor's home environment for further study, enjoyment and understanding. This unique feature, ability to effectively replay the experience at home, of the proposed system utilizes service-orientation to integrate third party media content, which is currently deficient from commercial augmented reality solutions.

Problem: How is Lean, a production-focused model being applied to non-productive focused industries.

Purpose: To examine how Lean has been applied to the department of Turbuhaler-Kvalitetskontroll and which parts have been successfully applied.

Problem statement: How does the implementation of Lean’s basic concept, which originated in the car industry, differentiate itself from the implementation of Lean in the pharmaceutical industry, in this case the department of Turbuhaler-Kvalitetskontroll at AstraZeneca.

Conclusions: The department has had success in its implementation of lean. They have developed and modified the basic concept in order to apply it and excluded the parts they did not consider necessary. Through their work they have accomplished numerous improvements in, among other things, the reduction of lead time. 

Networks are models that help us understanding and thinking about relationships between entities in the real world. Many of these networks are dynamic, i.e. connectivity changes over time. Understanding changes in connectivity means to understand interactions between elements of complex systems; how people create and break up friendship relations, how signals get passed in the brain, how business collaborations evolve, or how food-webs restructure after environmental changes. However, understanding static networks is already difficult, due to size, density, attributes and particular motifs; changes over time very much increase this complexity. Quantification of change is often insufficient, but beyond an analysis that is driven by technology and algorithms, humans dispose a unique capability of understanding and interpreting information in data, based on vision and cognition. This dissertation explores ways to interactively explore dynamic networks by means of visualization. I develop and evaluate techniques to unfold the complexity of dynamic networks, making them understandable by looking at them from different angles, decomposing them into their parts and relating the parts in novel ways. While most techniques for dynamic network visualization rely on one particular type of view on the data, complementary visualizations allow for higher-level exploration and analysis. Covering three aspects Tasks, Visualization Design and Evaluation, I develop and evaluate the following unfolding techniques: (i) temporal navigation between individual time steps of a network and improved animated transitions to better understand changes, (ii) designs for the comparison of weighted graphs, (iii) the Matrix Cube, a space-time cube based on adjacency matrices, allowing to visualize dense dynamic networks by, as well as GraphCuisine, a system to (iv) generate synthetic networks with the primary focus on evaluating visualizations in user studies. In order to inform the design and evaluation of visualizations, we (v) provide a task taxonomy capturing users' tasks when exploring dynamic networks. Finally, (vi) the idea of unfolding networks with Matrix Cubes is generalized to other data sets that can be represented in space-time cubes (videos, geographical data, etc.). Visualizations in these domains can inspire visualizations for dynamic networks, and vice-versa. We propose a taxonomy of operations, describing how 3D space-time cubes are decomposed into a large variety of 2D visualizations. These operations help us exploring the design space for visualizing and interactively unfolding dynamic networks and other spatio-temporal data, as well as may serve users as a mental model of the data.

Awareness of anthropogenic climate change has increased drastically in the last decade. With the help of the United Nations and the 17 sustainable development goals, there is now an international consensus that measures must be taken urgently. Actions towards reducing our climate impact have started to take place in various industries and one important sector is the food sector. This thesis is addressed to companies that help consumers make smarter and more climate friendly food decisions with the help of climate data. More specifically the scope of this thesis was to develop and evaluate a climate impact visualization application with consumers as the intended target group. The foundation of the intervention included theories in behaviour change and information visualization design principles. The application was evaluated with 11 participants looking to reduce their climate impact. A user study was conducted where the participants used the developed intervention by completing different tasks and then evaluated the experience and the different components of the application. The purpose of the evaluation was to gain qualitative insights of which components should be considered in the development process of a final product. The results indicate that visualizations of the products carbon dioxide emissions, receipt list and personal progress tracking were the most important components for the application. The result also gave positive indications that a similar application could help change the user’s behaviour when purchasing food to a more climate friendly pattern.
Medvetenheten om antropogena klimatförändringar har ökat drastiskt under det senaste decenniet. Med hjälp av FN och de 17 målen för hållbar utveckling finns det nu en internationell enighet om att åtgärder måste vidtas snarast. Åtgärder för att minska vår klimatpåverkan har börjat äga rum i olika branscher och en viktig sektor är livsmedelssektorn. Denna avhandling riktar sig till företag som hjälper konsumenter att fatta smartare och mer klimatvänliga livsmedelsbeslut med hjälp av klimatdata. Mer specifikt omfattar denna avhandling att utveckla och utvärdera en visualiseringsapplikation för klimatpåverkan med konsumenter som den avsedda målgruppen. Grunden för interventionen inkluderar teorier inom beteendeförändring och design-principer för informationsvisualisering. Applikationen utvärderades med 11 deltagare som ville minska sin klimatpåverkan. En användarstudie genomfördes där deltagarna använde den utvecklade applikationen genom att utföra olika uppgifter för att sedan utvärdera upplevelsen och de olika komponenterna i applikationen. Syftet med utvärderingen var att få kvalitativa insikter om vilka komponenter som bör beaktas i utvecklingsprocessen för en slutprodukt. Resultaten indikerar att visualiseringar av produkternas koldioxidutsläpp, kvittolista och personlig framstegsspårning var de viktigaste komponenterna för applikationen. Resultatet gav också positiva indikationer på att en liknande applikation skulle kunna hjälpa till att ändra användarens beteende när man handlar mat till ett mer klimatvänligt mönster.

Scopo di questa dissertazione è presentare una modalità di visualizzazione delle modifiche ad un documento indicativa del livello di priorità e del tipo di edit, sfruttando un raggruppamento di quelle che sono operazioni puramente meccaniche in operazioni di più alto livello, strutturali ed eventualmente semantiche. I principali editor usati e i principali sistemi di versionamento dei documenti offrono delle modalità di visualizzazione delle differenze scarne di significato, rendendo difficile per l’utente l’attribuzione di senso ai cambiamenti evidenziati sul testo. Ho quindi cercato di porre un rimedio al problema fornendo una struttura di edit e alcuni schemi visivi capaci di conferire una intuitiva attribuzione di significato alle modifiche.

Commercial buildings are one of the main contributors to energy consumption while both energy management and occupants’ consumption behaviour play crucial roles in how energy is consumed. This study explored the energy awareness of occupants in a commercial building with the goal to investigate how increased awareness could support behaviour change. For this purpose, a cooperative gamified visualization of energy consumption data, “EnerSpace”, is designed, implemented and evaluated. 8 occupants participated in this study who experienced a one-week baseline period and a one-week “EnerSpace” game period. In EnerSpace, the participants were divided into two teams and powered a spaceship with their energy saving respectively on a resource exploitation trip to Mars. Each participant had an avatar in the spaceship who introduced the participant’s personal consumption data. The energy conservation of the participants affects the moving speed of the spaceship and the living condition of their avatars. Participants were rewarded by a postcard sent by the avatars when reaching a destination. The results showed that the participants 1) decreased their energy consumption, 2) reported a fun and engaging experience with EnerSpace, and 3) felt motivated for energy conservation by different motives. This study indicated a potential for energy saving in a commercial building using a cooperative game.
Kommersiella byggnader är en av de främsta bidragsgivarna till energiförbrukningen, medan både energihantering och passagerarnas konsumtionsbeteende spelar en viktig roll i hur energi förbrukas. Denna studie undersökte medvetenheten om passagerare i en kommersiell byggnad med målet att undersöka hur ökad medvetenhet kunde stödja beteendets förändring. I detta syfte utformas, implementeras och utvärderas en kooperativ gammal visualisering av energiförbrukningsdata, "EnerSpace". 8 personer deltog i den här studien som upplevde en veckors baslinjeperiod och en veckas "EnerSpace" spelperiod. I EnerSpace delades deltagarna i två lag och drev ett rymdskepp med respektive energibesparing på en resursutnyttjandesresa till Mars. Varje deltagare hade en avatar i rymdskeppet som introducerade deltagarens personliga konsumtionsdata. Deltagarnas energibesparande påverkar rymdskeppens rörelsehastighet och deras avatars levnadsförhållande. Deltagarna belönades med ett vykort skickat av avatarer när de kom till en destination. Resultaten visade att deltagarna 1) minskade sin energiförbrukning, 2) rapporterade en rolig och engagerande erfarenhet av EnerSpace, och 3) kände sig motiverade för energibesparing med olika motiv. Denna studie indikerade en potential för energibesparing i en kommersiell byggnad med hjälp av en kooperativ gammal visualisering.

My creative project explores design for transit advocacy; aimed at shifting a car-dependent society into one where transit helps meet climate change, energy, and land-use challenges. It incorporates my research into aspects of designing for transit, an understanding of urbanism in Richmond and New York, and an appreciation of planning.

Final publication is available at http://www.nature.com/articles/srep12283
Kyoto University (京都大学)
0048
新制・課程博士
博士(医学)
甲第19559号
医博第4066号
新制||医||1013(附属図書館)
32595
京都大学大学院医学研究科医学専攻
(主査)教授 木村 剛, 教授 小池 薫, 教授 山下 潤
学位規則第4条第1項該当

The flow in a layer of volatile fluid driven by a horizontal temperature gradient is a fundamental transport model for numerous evaporative passive cooling applications. When a thin film of a volatile liquid is subject to a horizontal temperature gradient, changes in the surface tension at the free surface lead to Marangoni stresses that drive the flow. In a thicker liquid layer, the flow is also affected by buoyancy. This thesis describes experimental studies of convection driven by a combined action of Marangoni stresses and buoyancy in simple and binary volatile liquid layers confined in a sealed rectangular cavity heated at one end and cooled at the other. Experiments with varying concentrations of noncondensables (i.e., air) ca were performed to investigate their effect on the phase change and heat and mass transport. In the simple liquid, thermocapillary stresses drive the liquid near the free surface away from the heated end. Varying ca is shown to strongly affect the stability of this buoyancy-thermocapillary flow for Marangoni numbers Ma = 290 - 3600 and dynamic Bond numbers BoD = 0.56 - 0.82: removing air suppresses transition to multicellular and unsteady flow. The results are compared with numerical simulations and linear stability analysis. In the binary liquid considered here, a methanol-water (MeOH-H2O) mixture, solutocapillary stresses drive the flow near the free surface towards the heated end. Four distinct flow regimes are identified for this complex flow driven by thermocapillarity, solutocapillarity, and buoyancy, and are summarized in a flow regime map as a function of ca and the liquid composition (MeOH concentration). At low ca, solutocapillary effects are strong enough to drive the liquid near the free surface towards the heated end over the entire liquid layer, suggesting that binary-fluid coolants could significantly reduce film dryout.

In today’s turbulent business environment, an increasing number of businesses and organizations are finding themselves confronted with a crushing pressure to constantly reinvent themselves. Given such a business environment, coupled with high stakes and fierce competitiveness, it is quite unsurprising that most change efforts are reported to fail. Change communication, or rather the lack thereof, has been pointed out as one of the most important reasons. In recent years, many scholars have started to differentiate between participatory and programmatic change communication, elicited by a reconceptualization of change as continuous and emergent rather than episodic and planned. Participatory and programmatic are two diametrically different ways to approach change communication, and thus, they each require different tools, techniques and strategies. Several scholars have called attention to the shortage of tools, techniques and strategies suitable for participatory change communication in particular, however, empirical research remain scarce. At the same time, the data revolution is right upon us. Businesses that fail to harness the true potential of their data see themselves outcompeted by those who do. Even though data since long has been prophesied to transform management altogether, it is only in recent years that its application within the various subfields of management research has received serious attention by academia. However, the application of data in change management in general, and change communication in particular, has largely been left unaddressed.  In this thesis, we are exploring the role of data in the context of change communication through a case study at Skanska Rental, one of Sweden’s largest construction equipment rental companies. We delimit our study to only treat one of the most important aspects of data-driven communication; namely, data visualization. Our findings indicate that data visualization can facilitate change communication by encouraging it to be participatory. In particular, we find that data visualization has the merit of enthusing its audience, aligning the perception of the current state of affairs, reinforcing a data-driven culture, and facilitating interpersonal communication. We also call attention to three important considerations; (1) the democratization of data requires transparency trade-offs, (2) data visualization cannot replace interpersonal communication, but at most facilitate it, and (3) communication, although one of the most important, is not the sole precursor of successful change. We conclude our thesis by addressing the practical and theoretical implications of our conclusions, and lastly, by suggesting directions for future research in data-driven change communication.
I dagens turbulenta omvärld utsätts företag och organisationer för ett ständigt förändringstryck som inte visar några tecken på att avta. Givet ett sådant klimat, där mycket står på spel och där konkurrensen är förkrossande, är det inte förvånande att de flesta förändringsinitiativ misslyckas. Förändringskommunikation, eller snarare bristen därav, har ofta pekats ut som en av de viktigaste orsakerna till detta. På senare tid har många forskare börjat göra skillnad mellan två olika typer av förändringskommunikation: deltagande respektive programmatisk. Att betrakta förändringskommunikation genom denna dikotomi har föranletts av en ny syn på förändring i stort; snarare än att se förändring som episodisk och planerad har många forskare istället konceptualiserat förändring som kontinuerlig och framväxande. Olika tekniker, verktyg och strategier lämpar sig olika väl för de två olika typerna av förändringskommunikation. Många forskare har varnat för en bristande förståelse för i synnerhet de tekniker, verktyg och strategier som lämpar sig för den deltagande typen av förändringskommunikation. Under de senare åren har det förändringstryck många företag och organisationer står inför snarast ökat i styrka på grund av den datarevolution vi befinner oss mitt upp i. Trots att det sedan länge har förutspåtts att data har potentialen att vända spelplanen för företagsledning upp och ner, så är det bara på senare år som ämnet har åtnjutit företagsledningsforskningens fulla uppmärksamhet. Däremot finns det fortfarande ett underskott på akademisk forskning som adresserar hur data kan användas inom förändringsledning i allmänhet och förändringskommunikation i synnerhet. I denna masteruppsats utforskar vi den roll som data kan spela inom förändringskommunikation. Vårt empiriska material inhämtar vi genom en case-studie hos Skanska Rental, ett av Sveriges största uthyrningsföretag inom byggbranschen. Vi avgränsar vår studie genom att endast behandla en utav de viktigaste aspekterna av data-driven kommunikation, nämligen datavisualisering. Våra resultat indikerar att datavisualisering kan underlätta förändringskommunikation genom att göra den deltagande. I synnerhet finner vi att datavisualisering har potential att entusiasmera dess publik, linjera bilden av nuläget, förstärka en data-driven organisationskultur och fungera som en utgångspunkt för mellanmänsklig kommunikation. Vi identifierar också tre viktiga reservationer mot denna slutsats; (1) demokratisering av data fordrar ställningstagande gällande transparens, (2) datavisualisering kan inte ersätta mellanmänsklig kommunikation, och (3) kommunikation, om än viktig, är inte den enda förutsättningen för framgångsrik förändring. Vi avslutar vår uppsats med att adressera de praktiska och teoretiska implikationer som vår slutsats resulterar i, samt föreslår inriktningen för framtida forskning inom data-driven förändringskommunikation.

Food security and climate change mitigation are crucial missions for the agricultural sector and for global work on sustainable development. Concurrently, agricultural production is directly dependent on climatic conditions, making climate change adaptation strategies essential for the agricultural sector. There is consequently a need for researchers, planners, and practitioners to better understand how, why, and to what extent agriculture is vulnerable to climate change. Such analyses involve challenges in relation to the complex social– ecological character of the agricultural system and to the multiple conceptualizations and approaches used in analysing vulnerability. The aim of this thesis is to identify how vulnerability assessments can be used to represent climate-related vulnerability in Nordic agriculture, in order to advance the methodological development of indicator-based and geographic visualization methods. The following research questions are addressed: (i) How can agricultural vulnerability to climate change and variability in the Nordic countries be characterized? (ii) How do selections, definitions, and emphases of indicators influence how vulnerability is assessed? (iii) How do estimates of vulnerability vary depending on the methods used in assessments? (iv) How can geographic visualization be applied in integrated vulnerability assessments? This thesis analyses and applies various vulnerability assessment approaches in the context of Nordic agriculture. This thesis demonstrates that various methods for composing vulnerability indices result in significantly different outcomes, despite using the same set of indicators. A conceptual framework for geographic visualization approaches to vulnerability assessments was developed for the purpose of creating transparent and interactive assessments regarding the indicating variables, methods and assumptions applied, i.e., opening up the ‘black box’ of composite indices. This framework served as the foundation for developing the AgroExplore geographic visualization tool. The tool enables the user to interactively select, categorize, and weight indicators as well as to explore the data and the spatial patterns of the indicators and indices. AgroExplore was used in focus group settings with experts in the Swedish agricultural sector. The visualization-supported dialogue results confirm the difficulty of selecting and constructing indicators, including different perceptions of what indicators actually indicate, the assumption of linear relationships between the indicators and vulnerability, and, consequently, that the direction of the relationship is predefined for each indicator. This thesis further points at the inherent complexity of agricultural challenges and opportunities in the context of climate change as such. It is specifically emphasized that agricultural adaptation policies and measures involve trade-offs between various environmental and socio–economic objectives, and that their implementation could furthermore entail unintended consequences, i.e., potential maladaptive outcomes. Nevertheless, it proved difficult to validate indicators due to, e.g. matters of scale and data availability. While heavy precipitation and other extreme weather events are perceived as the most relevant drivers of climate vulnerability by the agricultural experts participating in this study, statistical analyses of historical data identified few significant relationships between crop yield losses and heavy precipitation. In conclusion, this thesis contributes to the method development of composite indices and indicator-based vulnerability assessment. A key conclusion is that assessments are method dependent and that indicator selection is related to aspects such as the system’s spatial scale and location as well as to indicator thresholds and defined relationships with vulnerability, recognizing the contextual dependency of agricultural vulnerability. Consequently, given the practicality of indicator-based methods, I stress with this thesis that future vulnerability studies must take into account and be transparent about the principles and limitations of indicator-based assessment methods in order to ensure their usefulness, validity, and relevance for guiding adaptation strategies.
För jordbrukssektorn och global hållbar utveckling i stort är matsäkerhet och mitigering av klimatförändringar viktiga angelägenheter. Samtidigt är jordbruksproduktionen ofta direkt beroende av klimatförhållanden, vilket gör klimatanpassningsstrategier mycket centrala för sektorn. Forskare, planerare och aktörer behöver förstå hur, varför och i vilken omfattning jordbruket är sårbart inför klimatförändringar. Sådana analyser inbegriper även de utmaningar som skapas genom jordbrukets komplexa socio-ekologiska karaktär, och de många utgångspunkter och tillvägagångssätt som används för att bedöma sårbarhet. Syftet med denna avhandling är att identifiera hur sårbarhetsbedömningar kan representera klimatrelaterad sårbarhet i nordiskt jordbruk, och i och med detta har avhandlingen som avsikt att utveckla metodologin för indikatorbaserade- och geografiska visualiseringsmetoder. Följande forskningsfrågor avhandlas: (i) Hur kan det nordiska jordbrukets sårbarhet inför klimatvariation och förändringar karaktäriseras? (ii) Hur påverkar urval, definitioner och betoningar av indikatorer bedömningar av sårbarhet? (iii) Hur varierar uppskattningar med bedömningsmetod? (iv) Hur kan geografisk visualisering användas i integrerade såbarhetsbedömningar? För att svara på dessa frågor analyseras och tillämpas olika tillvägagångssätt att bedöma sårbarhet inom nordiskt jordbruk. Avhandlingen visar att olika metoder för sårbarhetskompositindex resulterar i signifikanta skillnader mellan index, trots att samma indikatorer och data används. Ett konceptuellt ramverk för sårberhetsbedömningar där geografisk visualisering används, har utvecklats för att möjliggöra transparens avseende till exempel. vilka variabler, metoder och antaganden som används i kompositindex. Detta ramverk har följaktligen legat till grund för att utveckla ett geografiskt visualiseringsverktyg – AgroExplore. Verktyget möjliggör interaktivitet där användaren kan välja, kategorisera och vikta indikatorer, och dessutom utforska data och spatiala mönster av indikatorer och kompositindex. AgroExplore användes i denna avhandling för att stödja fokusgruppdialoger med experter inom den svenska jordbrukssektorn. Resultaten från dessa workshops bekräftar svårigheten med att välja och skapa indikatorer. Dessa svårigheter innefattar olika uppfattningar om vad indikatorer representerar, antagandet om linjära samband mellan indikatorerna och sårbarhet, och följaktligen att sambandens riktning är fördefinierade för respektive indikator. Utöver de konceptuella och metodologiska utmaningarna med sårbarhetsbedömningar visar avhandlingen på komplexa svårigheter och möjligheter för jordbruket vid klimatförändringar. Särskilt framhålls att klimatanpassningspolitik och åtgärder inom jordbruket medför konflikter och avvägningar mellan olika miljö- och socio-ekonomiska mål. Implementering av sådana anpassningsåtgärder kan vidare innebära oönskade konsekvenser, så kallad missanpassning. Trots ökad kunskap gällande nordiska jordbrukets sårbarhet inför klimatförändringar har det visats sig vara svårt att statistiskt validera indikatorer på grund av, exempelvis, skalproblematik och datatillgänglighet. Samtidigt som experterna ansåg att kraftig nederbörd och andra extrema väderhändelser är de mest relevanta drivkrafterna till klimatsårbarhet visar den statistiska analysen av historiska data på få signifikanta samband mellan förlorad skördeavkastning och kraftig nederbörd. Denna avhandling bidrar till metodutveckling av kompositindex och indikatorbaserade metoder för sårbarhetsbedömningar. En viktig slutsats är att bedömningar är metodberoende och att valet av indikatorer är relaterat till aspekter såsom systemets utbredning och den spatiala skalan av bedömningen. Även indikatorernas tröskelvärden och hur deras relation till sårbarhet är definierade anses vara viktiga faktorer som påverkar hur indikatorer representerar sårbarhet, vilket visar på sårbarhetsbedömningars kontextuella beroende. I och med de rådande bristerna hos indikatorbaserade metoder, som bland annat har identifierats i denna avhandling, vill jag framhålla vikten av att sårbarhetsbedömningar bör vara transparanta gällande den tillämpade metodens principer, antaganden och begräsningar. Detta för att säkerställa användbarhet, giltighet och relevans, om metoden och bedömningen ska ligga till grund för anpassningsstrategier hos såväl politiker, planerare och lantbrukare.

This is deliverable of the Nordic Centre of Excellence for Strategic Adaptation Research (NORD-STAR), funded by the Nordic Top-level Research Initiative Sub-programme ‘Effects Studies and Adaptation to Climate Change’.

The work has also been supported by the Swedish Research Council FORMAS under Grant No. 2013-1557 ‘Identifying thresholds for maladaptation in Nordic agriculture’

Les logiciels évoluent au fil du temps avec la modification, l'ajout et la suppression de nouvelles classes, méthodes, fonctions, dépendances. Une conséquence est que le comportement peut être placé dans de mauvais paquetages et casser la modularité du logiciel. Une bonne organisation des classes dans des paquetages identifiables facilite la compréhension, la maintenance, les tests et l'évolution des logiciels. Nous soutenons que les responsables manquent d'outils pour assurer la remodularisation logicielle. La maintenance des logiciels nécessite des approches qui aident à (i) la compréhension de la structure au niveau du paquetage et l'évaluation de sa qualité; (ii) l'identification des problèmes de modularité, et (iii) la prise de décisions pour le changement. Dans cette thèse nous proposons ECOO, une approche qui aide la remodularisation. Elle concerne les trois domaines de recherche suivants: (i) Comprendre les problèmes de dépendance entre paquetages. Nous proposons des visualisations mettant en évidence les dépendances cycliques au niveau des paquetages; (ii) Proposer des dépendances qui devraient être changées. L'approche propose des dépendances à changer pour rendre le système plus modulaire; (iii) Analyser l'impact des changements. L'approche propose une analyse d'impact du changement pour essayer les modifications avant de les appliquer sur le système réel. L'approche présentée dans cette thèse a été validée qualitativement et les résultats ont été pris en compte dans la réingénierie des systèmes analysés. Les résultats obtenus démontrent l'utilité de notre approche.

A novel surface structure comprising dendritically ordered nano-particles of copper was developed during the duration of this thesis research project. A high current density electrodeposition process, where hydrogen bubbles functioned as a dynamic mask for the materials deposition, was used as a basic fabrication method. A post processing annealing treatment was further developed to stabilize and enhance the mechanical stability of the structure. The structure was studied quite extensively in various pool boiling experiments in refrigerants; R134a and FC-72. Different parameters were investigated, such as; thickness of the porous layer, presence of vapor escape channels, annealed or non-annealed structure. Some of the tests were filmed with a high speed camera, from which visual observation were made as well as quantitative bubble data extracted. The overall heat transfer coefficient in R134a was enhanced by about an order of magnitude compared to a plain reference surface and bubble image data suggests that both single- and two-phase heat transfer mechanisms were important to the enhancement. A quantitative and semi-empirical boiling model was presented where the main two-phase heat transfer mechanism inside the porous structure was assumed to be; micro-layer evaporation formed by an oscillating vapor-liquid meniscus front with low resistance vapor transport through escape channels. Laminar liquid motion induced by the oscillating vapor front was suggested as the primary single-phase heat transfer mechanism. The structure was applied to a standard plate heat exchanger evaporator with varying hydraulic diameter in the refrigerant channel. Again, a 10 times improved heat transfer coefficient in the refrigerant channel was recorded, resulting in an improvement of the overall heat transfer coefficient with over 100%. A superposition model was used to evaluate the results and it was found that for the enhanced boiling structure, variations of the hydraulic diameter caused a change in the nucleate boiling mechanism, which accounted for the largest effect on the heat transfer performance. For the standard heat exchanger, it was mostly the convective boiling mechanism that was affected by the change in hydraulic diameter. The structure was also applied to the evaporator surface in a two-phase thermosyphon with R134a as working fluid. The nucleate boiling mechanism was found to be enhanced with about 4 times and high speed videos of the enhanced evaporator reveal an isolated bubble flow regime, similar to that of smooth channels with larger hydraulic diameters. The number and frequency of the produced bubbles were significantly higher for the enhanced surface compared to that of the plain evaporator. This enhanced turbulence and continuous boiling on the porous structure resulted in decreased oscillations in the thermosyphon for the entire range of heat fluxes.
QC 20111111

Coronapandemin i världen är ett faktum. För att minska smittspridningen i samhället, så bör individer följa regeringens samt myndigheternas rekommendationer. De restriktioner som är gällande i Sverige den 14:e maj är lindriga och under denna pandemi har offentliga platser, restauranger och butiker varit fortsatt öppna (Krisinformation.se 2020). Folkhälsomyndighetens (2020) strategi går ut på att platta ut kurvan så att hälso- och sjukvården upprätthåller en tillräckligt hög kapacitet för att vårda svårt sjuka patienter. För att minska smittspridningen är det av betydelse att enskilda individer följer rekommendationerna om att hålla avstånd, tvätta händerna och inte besöka äldre över 70 år (Folkhälsomyndigheten 2020). Forskning inom IKT pekar på att denna form av information och kommunikation relaterad till kris bör riktas långsiktigt och även inom andra kanaler än sociala medier (Soden & Palen, 2018). Inom detta område har nudging blivit en allt mer utpräglad metod för att motivera individer till beteendeförändringar inom specifika situationer Caraban et al (2019). Att informationen är tydlig och pålitlig är av stor betydelse (The Lancet, 2020). Kvalitativa Intervju- och observationsstudier pekar på att det finns ett behov av att motivera och påminna individer om att följa restriktionerna även utomhus. Genom att situationsanpassa offentliga skärmar och addera sensorer, så vill denna studie verka för att motivera individer till att följa Folkhälsomyndighetens rekommendationer (2020). Designen föreslår en situationsanpassad digital krisinformation som placeras i offentliga parker under coronapandemin. Konceptet innebär att nudga individer till att hålla avstånd i parker och på så sätt bidra till att minska smittspridningen i samhället. Designen tar hänsyn till tidigare forskning inom IKT, nudging och berättande visualisering. För att sedan bidra till forskningen genom att representera en ny metod för hur digital krisinformation kan förmedlas under pandemier.
The global Corona crisis is a fact. Individuals should follow the government's recommendations to reduce the spread of the virus in society. The Swedish strategy, which still remains at the date of 14th of May, means that public places, as well as restaurants and shops, are kept open (Krisinformation.se 2020). The strategy according to the Public Health Authority (Folkhälsomyndigheten 2020) is to flatten the curve so that healthcare can manage to take care of individuals in need of intensive care. In order to reduce the spread of the virus, it is important that individuals are following the recommendations on keeping distance, washing hands and avoiding necessarily contact with elderly over 70 years (Public Health Authority; Folkhälsomyndigheten 2020). Previous research in ICT science indicates that this form of information and communication should be used long term. Research in ICT points out that this form of crisis information should be used also in other channels than Social media (Soden & Palen 2018). According to the scientists Carbal et al (2019), nudging has played an important role for motivating individuals to change behaviour in a particular situation. Qualitative interviews, as well as observational studies, indicate that there is a need to motivate and remind individuals to follow the restrictions even outdoors. This essay aims to motivate individuals to follow the recommendations of the Public Health Authority (Folkhälsomyndigheten 2020). This essay suggests a situation-based design that passes ordinary digital crisis information placed in public parks during the Corona Pandemic. The concept involves nuding individuals to keep their distance in parks, and reduce the spread of the virus in the society. The design takes into account previous research in ICT, nudging and Narrative visualization. Furthermore, this essay aims to represent a new method for how Digital Crisis Information can be disseminated during pandemics.

Ett centralt problem i strävan efter att minska energianvändningen i hushåll genom beteendeförändringar är att energi till stora delar är en osynlig produkt. Avhandlingen strävar efter att utveckla kunskap som kan bidra till mer hållbar utveckling genom att analysera tre företeelser som på ett konkret sätt synliggör energi och energirelaterat beteende: ett lokalt värmesystem, en s.k. Power Aware Cord och en dagboksmetod. Hur människor förstår sin energianvändning analyseras med hjälp av en modifierad version av den domesticeringsteori som utvecklats av Silverstone et al (1992). I centrum står paradoxen att de visualiserande företeelserna riskerar att själva osynliggöras genom att de domesticeras. Värmesystemet har haft en bristande funktion, vilket har varit den faktor som mest effektivt visualiserat systemet. Solfångarnas visuella dominans i områdets arkitektur har bidragit till att medvetandegöra solen som energikälla. Ett teknikrum och olika experter har också medvetandegjort själva värmesystemets existens. Såväl systemet som helhet som hushållens egen del i detta har visualiserats. Power Aware Cord liknar en vanlig grendosa, men den visar elanvändningen (effekten) hos den utrustning som kopplas till den. Energin visualiseras med hjälp av ett blått ljus i sladden vars intensitet anpassas efter watttalet som passerar genom sladden. Power Aware Cords styrka ligger i att den bidrar till att apparaters energianvändning visualiseras. Tidsdagboken visualiserar hushållsmedlemmarnas vardagliga aktiviteter på ett bredare plan än enbart i relation till energianvändning. Analysen visar att den redan osynliga resursen energi, som blivit än mer osynliggjort genom domesticering, kan avdomesticeras genom olika former för visualisering. Visualiseringsformerna riskerar dock att själva domesticeras. För att dessa ska ha varaktig effekt behövs strategier för att undvika detta.
One problem in promoting sustainable energy use is that energy is taken for granted. Energy as resource needs to be made visible. This dissertation aims to develop knowledge that can contribute to more sustainable development by analyzing different ways to visualize domestic energy systems. Three different forms of visualization are analyzed: a locally situated heating-system, the Power Aware Cord, and a diary method. How people understand their energy use is analyzed using a modified version of domestication theory as developed by Silverstone et al. (1992). Another focus is the paradox that forms of visualization themselves risk becoming invisible by virtue of being domesticated. The heating system still does not function as intended, and the non-functioning of the heating system has been the most effective means of visualizing the system. The solar collectors are visible and are a dominant element of the area’s architecture; this has helped visualize, make people aware of, and confer an understanding of the sun as an energy source. A technical control room and technicians have also helped visualize the existence of the heating system. The system as a whole, and the households’ own parts of it, has been visualized. The Power Aware Cord is the general shape of an extendable power strip, with the additional integration of voltage-measuring electronics and electroluminescent wire. This additional wire contains a phosphor layer that glows when an altering current is introduced. The cords’ strength lies in visualizing the household energy use of particular electrical devices. The time diary method visualizes the household members’ individual and inter-related ctivity patterns in a broader, more general way. The analysis shows that the already invisible resource energy, which has been made doubly invisible through domestication, can be de-domesticated through the domestication of forms of visualization. At the same time, the forms of visualization themselves risk being made invisible by being domesticated; for forms of visualization to have any lasting effect, strategies for avoiding this must be developed.

De plus en plus de logiciels sont développés par des équipes de développeurs travaillant de manière collaborative en parallèle. Les développeurs peuvent altérer un ensemble d'artéfacts, inspecter et in- tégrer le code de changements faits par d'autres développeurs. Par exemple, les corrections d'erreurs, les améliorations ou nouvelles fonctionnalités doivent être intégrées dans la version finale d'un logi- ciel et ceci à différents moments du cycle de développement. A un niveau technique, le processus de développement collaboratif est mis en pratique à l'aide d'outils de contrôle de versions (ex: git, SVN). Ces outils permettent aux développeurs de créer leurs propres branches de développement, faisant des tâches de fusion ou d'intégration de ces branches une partie intégrante du processus de développement. Les systèmes de versions de contrôle utilisent des algorithmes de fusion pour aider les développeurs à fusionner les modifications de leur branche dans le base de code commune. Cependant ces techniques travaillent à un niveau lexical, et elles ne garantissent pas que le système résultant soit fonctionnel. Alors que l'utilisation de branches offre de nombreux avantages, la fusion et l'intégration de mod- ifications d'une branche sur une autre est difficile à mettre en oeuvre du fait du manque de support pour assister les développeurs dans la compréhension d'un changement et de son impact. Par exemple, l'intégration d'un changement peut parfois avoir un effet inattendu sur le système et son comporte- ment menant à des bugs subtiles. De plus, les développeurs ne sont pas aidés lors de l'évaluation de l'impact d'un changement, ou lors de la sélection de changements à intégrer d'une branche vers une autre (cherry picking), en particulier lorsque ces branches ont divergé. Dans cette dissertation, nous présentons une approche dont le but est d'apporter des solutions à ces problèmes pour les développeurs, et plus précisément les intégrateurs. Cette approche se base sur des outils et solutions semi-automatisés aidant à de changements la compréhension à l'intérieur d'une branche ou entre branches. Nous nous attachons à satisfaire les besoins en information des intégrateurs quand ils doivent comprendre et intégrer des changements. Pour cela, nous caractérisons les changements et/ou séquences de changements et leurs dépendances. Ces caractérisations sont basées sur la représentation comme citoyens de première classe de l'historique du système et des changements approtés considérant les entités logicielles (ex: classes ou méthodes) et leurs relations plutôt que des fichiers et du texte comme le font les outils de con- trôle de versions. Pour cela, nous proposons une famille de méta-modèles (Ring, RingH, RingS et RingC) qui offrent une représentation des entités du système, de son historique, des changements apportés dans les différentes branches et de leurs dépendances. Des instances de ces meta-modèles sont ensuite utilisées par nos outils destinée à assister les intégrateurs: Torch, un outil visuel qui car- actérise les changements, et JET un ensemble d'outils qui permettent de naviguer dans des séquences de changements. Mots clés: programmation à objets; méta-modèles; historique et versions de programmes; vi- sualisation de programmes; fusion sémantique; analyse de programmes. Samenvatting Hedendaagse software is het resultaat van een collaboratief ontwikkelingsproces met meerdere teams van ontwikkelaars. Het doel van dit proces is om het toe te laten dat ontwikkelaars gelijktijdig en onafhankelijk van elkaar kunnen werken. Hiervoor hebben ze toegang tot een gedeelde verzameling van artefacten die ze kunnen aanpassen, en hebben ze de mogelijkheid om de aanpassingen die an- dere ontwikkelaars maken aan de broncode te inspecteren en te integreren. Zo kunnen bijvoorbeeld bug fixes, verbeteringen en nieuwe functionaliteit tijdig geïntegreerd worden in een versie van een softwaresysteem. Op een technisch niveau wordt dit collaboratief ontwikkelingsproces ondersteund door versiecon- trolesystemen. Gezien deze versiecontrolesystemen het mogelijk maken voor ontwikkelaars om in hun eigen branch van het systeem te werken, zijn merging en integratie een volwaardig onderdeel van het ontwikkelingsproces geworden. Hiertoe bieden deze versiecontrolesystemen geavanceerde en geautomatiseerde merge-technieken aan die ontwikkelaars helpen om hun aanpassingen samen te voegen met de aanpassingen van andere ontwikkelaars. Echter, deze technieken garanderen niet dat het resultaat van dit samenvoegen tot een werkend systeem zal leiden. Alhoewel het gebruik van branching binnen het ontwikkelingsproces vele voordelen biedt, wor- den de hieraan verbonden taken van het invoegen en integreren van aanpassingen bemoeilijkt door een gebrek aan ondersteuning. Bijvoorbeeld, het integreren van aanpassingen kan een onverwachte impact hebben op het ontwerp of het gedrag van het systeem, wat dan weer kan leiden tot de intro- ductie van subtiele fouten. Bovendien wordt er aan ontwikkelaars geen ondersteuning geboden bij het integreren van veranderen die afkomstig zijn uit een andere branch van het systeem (het zogenaamde cherry picking), bij divergerende branches, bij het zoeken naar afhankelijkheden tussen aanpassingen, of bij het inschatten van de mogelijke impact van een verzameling veranderingen op het systeem. In dit proefschrift stellen we een techniek voor die bovenvermelde problemen aanpakt door on- twikkelaars - en in het bijzonder integrators - semi-automatisch te assisteren bij het integreren van aanpassingen, zowel binnen één branch als tussen verschillende branches. We leggen hierbij de klem- toon op het helpen van integrators om de informatie te verkrijgen die ze nodig hebben om aanpassin- gen aan de software te begrijpen en te integreren. Hiervoor maken we gebruik van een karakterisering van aanpassingen en van aanpassingsstromen (dit zijn een opeenvolging van aanpassingen binnen een branch), te samen met een karakterisatie van de afhankelijkheden tussen de aanpassingen. Deze karakteriseringen zijn gebaseerd op een eersterangs voorstelling van de historiek van een systeem en de aanpassingen die binnen deze historiek werden uitgevoerd. Deze voorstelling is gedefinieerd in termen van de feitelijke programma-entiteiten, in plaats van bestanden en tekst die integrators niet de noodzakelijke informatie verschaffen. Hiervoor bieden we een familie van meta- modellen aan (Ring, RingH, RingS en RingC) die een implementatie verschaffen van de voorstelling van programma-entiteiten, de historiek van het systeem, aanpassingen, en de afhankelijkheden tussen aanpassingen. Deze meta-modellen bieden ook de analyses aan om versies van een systeem te vergeli- jken, en om aanpassingen en afhankelijkheden te berekenen. Verder stellen we tools voor die, gebruik makende van instanties van onze meta-modellen, het mogelijk maken voor integrators om de karak-iv teriseringen van aanpassingen te analyseren. De visuele tool Torch en de verzameling van JET-tools, voorzien in de informatie die noodzakelijk is om assistentie te bieden bij respectievelijk het integreren van aanpassingen binnen één branch en tussen verschillende branches. Trefwoorden: objectgericht programmeren; meta-modellen; historiek en versies van pro- gramma's; visualisatie; semantisch mergen; programma-analyses

The purpose of this thesis was to examine the relationship between feelings and visualizations of climate change. A case study was done on visualizations of climate change from a web page concerning climate change published by the Swedish newspaper Expressen and from the American photographer Gary Braasch’s web page “World view of global warming”. The thesis is based on the article ”Emotional anchoring and objectification in the media reporting on climate change” by Birgitta Höijer. I have been aiming to understand the feelings of fear, hope, guilt, compassion and nostalgia through semiotic theories of icon, index and symbol.

Previous research has proven the difficulties in bringing the issue of climate change up on the public agenda – which is connected to the difficulties of visualizing climate change. The nature of climate change being slow and hard to spot on an individual level has been highlighted as a cause of both of these difficulties. Pictures and photos have in this thesis been seen as the “interface” between science and the public – and hence decoders of the science of climate change. Höijer’s article about feelings has been used to understand this process of decoding.

The results show that the analyzed material could be linked to and described by the semiotic theories of icon, index and symbol. The emotional anchoring found in the material and the semiotic application have been shown to work complementarily with each other, leading to a broader understanding of the material’s relationship to social cognitions. The results further demonstrated that context is essential in some of the analyzed visualizations of climate change. Generic pictures found in the material could have been regarded as icon, index or symbol of other messages – but is through its contexts anchored with feelings, and becomes visualizations of climate change. The analysis also suggests that if icons of nature could be connected with feelings – so could nature itself. The consequences are speculated to lead to objectification of nature and ecophobia. By objectifying nature and using generic pictures, the material’s relationship to the concepts of “truth” and “myth” is questioned.

In conclusion, understanding of the analyzed material is advantageously achieved through complementary use of Höijers emotional categories and the semiotic theories of icon, index and symbol.

Positioned between writing and drawing, the diagram is proposed by John Berger as an alternative strategy for articulating encounters with landscape. A diagrammatic approach offers a schematic vocabulary that can compress time and offer a spatial reading of information. Situated within the contemporary field of direct data visualisation, my practice-led research interprets Berger’s ‘Field’ essay as a guide to producing four field | studies within a suburban park in Canberra. My seasonal investigations demonstrate how applying the conventions of the pictorial list, dot-distribution map, routing diagram and colour-wheel reveals subtle ecological and biographical narratives.

碩士
國立清華大學
動力機械學系
84
The purposes of the experimental study are to understand the flow pattern and to obtain the critical parameters for the onset of longitudinal vortices in rotating boundary layer. The cross-section photos show that (1) roll-cells at rotation speed 0 rpm are induced by the smoke injection flow. (2) At rotation speed 15 rpm, the roll-cells grow up along the flow direction and the number of the roll-cells is eleven. (3) At rotation speed 24 rpm, the roll-cells grow up quicker. The repulsion and coelescence of the roll-cells start and the roll-cells become asymmetric in the downstream of the vortex onset position. The side-view photos show that (1) at rotation speed larger than 15 rpm, the smoke boundary layer grows up along the flow direction (2) at rotation speed larger than 30 rpm, the vortices grow up so guickly that roll- cells break down before passing the exit. For the side-view photos, it is possible to determine the onset position of longitudinal vortices in the rotating boundary layer flow. The comparison of present and previous studies is made. The relationship of critical Goertler Number vs. the dimensionless wave number in this experiment fit those of theoretical calculations of Hwang, Lin, and Lin in preparation in reasonal error range.

碩士
國立交通大學
機械工程系所
107
To enhance heat transfer performance, rib has been widely applied to channel wall. In our research, vertical cooling channel with cross section of right angle trapezoid has been considered. Heater and rib were applied to the right angle wall and inclined wall with rib height-to-hydraulic diameter as 0.128. Ribs with V-shaped, full X-shaped and modified X-shaped which pointing upstream and downstream had been investigated. Dry air was applied as the cooling fluid, and the Reynolds numbers were from 10000~40000. Infrared camera (IR camera) has been used to capture the temperature distribution of different rib types, including single rib and staggered arrangement with two rib spacing (P/e=10 and 20). Result shows, at right angle wall of the trapezoid channel, zones near the shorter side with smaller cross section area, fluid has been squeezed and speeded up, causing higher heat transfer. At the bottom edge of the inclined wall, the flow was blocked by the sharp angle of the corner, resulting in lower heat transfer comparing to upper edge of the inclined wall. For the case of single rib, full X type has the larger high heat transfer region located at middle part of the rib and downstream area. Its Nusselt number ratio is 11~15% higher than V-shaped rib. For staggered arrangement, full X with P/e=20 has comparable heat transfer comparing to V rib with P/e=10. However, the friction factor of X rib is a drawback because higher friction factor causes lower thermal performance. In conclusion, in single rib and staggered arrangement, despite full X rib has larger and higher heat transfer region, modified X ribs decrease the friction factor and successfully maintain acceptable thermal performance.