Η χωροθέτηση εγκαταστάσεων σε ένα ανταγωνιστικό περιβάλλον αποτελεί σημαντικό πρόβλημα που μπορεί να επηρεάσει την αποτελεσματικότητα και αποδοτικότητα μιας επιχείρησης. Διάφορες ποσοτικές μέθοδοι έχουν προταθεί ως βοήθεια για τη λήψη τέτοιων αποφάσεων. Ενώ τα συνήθη μοντέλα χωροθέτησης μελετούν την εγκατάσταση μονάδων μιας επιχείρησης, τα μοντέλα ανταγωνιστικής χωροθέτησης μελετούν και τις αντιδράσεις των ανταγωνιστικών επιχειρήσεων. Η παρούσα εργασία παρουσιάζει τα πιο σημαντικά και ευρέως γνωστά μοντέλα, που χρησιμοποιούνται στη χωροθέτηση ανταγωνιστικών εγκαταστάσεων. Εστιάζει κυρίως σε μοντέλο ακέραιου προγραμματισμού 0-1 για εγκατάσταση μονάδων ιεραρχικών επιπέδων, όταν στην περιοχή ενδιαφέροντος δραστηριοποιούνται και ανταγωνιστικές μονάδες. Το μοντέλο επιτρέπει τη χωροθέτηση νέων μονάδων καθώς και την επανεγκατάσταση υπαρχόντων. Τέλος, παρουσιάζεται μια εφαρμογή αυτής της μεθόδου βασισμένη σε πραγματικά δεδομένα μεγάλης Ελληνικής τράπεζας. / Facilities Location in a competitive environment is an important problem that can significantly affect the future performance of an organization. Various quantitative methods have been proposed as an aid to such decisions. Whereas the usual location models allow only one firm or facility to locate, competitive models permit other facilities to react to their competitor’s actions. This work presents the most important and common models, that are used in such situations. It mostly focuses on a 0-1 integer programming model for locating services with a hierarchical structure when there is competition in the region of interest. The model allows the location of new servers as well as the relocation of existing servers. Finally, an application of this technique is presented, based on real data from a big Greek bank.

The current Internet architecture presents a barrier to accommodate the vigorous arising demand for deploying new network services and applications. The next-generation architecture views the network virtualization as the gateway to overcome this limitation. Network virtualization promises to run efficiently and securely multiple dedicated virtual networks (VNs) over a shared physical infrastructure. Each VN is tailored to host a unique application based on the user’s preferences. This thesis addresses the problem of the efficient embedding of multiple VNs onto a shared substrate network (SN). The contribution of this thesis are twofold: First, a novel hierarchical SN management framework is proposed that efficiently selects the optimum VN mapping scheme for the requested VN from more than one proposed VN mapping candidates obtained in parallel. In order to accommodate the arbitrary architecture of the VNs, the proposed scheme divides the VN request into smaller subgraphs, and individually maps them on the SN using a variation of the exact subgraph matching techniques. Second, the physical resources pricing policy is introduced that is based on time-ofuse, that reflects the effect of resource congestion introduced by VN users. The preferences of the VN users are first represented through corresponding demand-utility functions that quantify the sensitivity of the applications hosted by the VNs to resource consumption and time-of-use. A novel model of time-varying VNs is presented, where users are allowed to up- or down-scale the requested resources to continuously maximize their utility while minimizing the VNs embedding cost. In contrast to existing solutions, the proposed work does not impose any limitations on the size or topology of the VN requests. Instead, the search is customized according to the VN size and the associated utility. Extensive simulations are then conducted to demonstrate the improvement achieved through the proposed work in terms of network utilization, the ratio of accepted VN requests and the SP profits.

High performance natural materials typically employ highly tuned structures spanning the nanoscopic to macroscopic length scales. Synthetically recapitulating this degree of complexity has become a unifying goal connecting the fields of chemistry, nanoscience, biology, and materials science. One common strategy is to direct the bottom up assembly of nanoparticle building blocks into hierarchical structures using stimuli such as electric fields. Despite the promise and great versatility of electric fields, there are many knowledge gaps surrounding their use to assemble highly complex structures. In this thesis, we explore the assembly of nanoparticles into hierarchical structures through dielectrophoresis (DEP), or the motion of polarizable objects in non-uniform electric fields. Critically, through a systematic approach, we study the fundamental polarizability of individual particles, the assembly of particle dimers, and finally the emergence of macroscopic structure from nanoscopic particles. Interweaving these explorations are instrumentation advances that broaden our ability to measure fundamental particle properties and explore hierarchical structures. Initially, we measure the polarizability of nanoparticles in solution using fluorescence microscopy. Specifically, we quantify the polarizability of solution-phase semiconductor quantum dots (QDs) for the first time. Through analyzing the thermodynamic distribution of particles in a microfluidic device with a non-uniform electric field profile, we identify a striking 30-fold increase in polarizability in the presence of low salt conditions due to the Debye screening length being commensurate with the particle size. This increase in polarizability indicates that nanoparticles assemble far more rapidly and easily than previously predicted. Next, we study the assembly of nanoparticles in the vicinity of anisotropic template particles as a path to realizing hierarchical structures. Specifically, we explore eight particle geometries using finite element analysis and find a >10-fold local field enhancement near some shapes, potentially promoting hierarchical assembly. We subsequently introduce a framework for predicting the assembly outcome of particles with multiple distinct sizes and shapes that includes thermodynamic and kinetic considerations. Then, we perform experiments demonstrating the hierarchical assembly of QDs into macroscopic structures. Despite theory predicting the formation of chains, we observe a macroscopic foam-like cellular phase when the QDs experience a combination of alternating current (AC) and direct current (DC) voltages. The resulting materials are both highly hierarchical in that they are 200 µm thick materials comprised of 20 nm particles, but they also represent extremely low-density materials. Finally, we report the invention of a novel instrument for imaging hierarchical materials. Specifically, we describe a massively parallel atomic force microscope with >1000 probes that is made possible through the combination of a new cantilever-free probe architecture and a scalable optical method for detecting probe-sample contact that provides sub-10 nm vertical precision. / 2022-09-28T00:00:00Z

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京都大学 / 新制・課程博士 / 博士(工学) / 甲第23922号 / 工博第5009号 / 新制||工||1782(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 竹中 幹人, 教授 古賀 毅, 教授 中村 洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Human bone tissue has an inherent hierarchical structure, which is integral to its material properties. It is primarily composed of a collagen fiber matrix that is mineralized with hydroxyapatite. A comprehensive understanding of bone and the linkages between structural and cellular organization is imperative to developing fundamental knowledge that can be applied to better our understanding of bone disease manifestations and its interaction with implant devices. Herein, this thesis investigated non-traditional methods for evaluating bone structure across the nano- and meso-length scales. Firstly, due to the inhomogeneous organization of collagen fibrils and mineral platelets of bone ultrastructure, a suitable methodology for the investigation of both phases needed to be generated. In this work, focused ion beam (FIB) microscopy was employed to create site-specific scanning transmission electron microscopy (STEM) lift-outs of human osteonal bone that could be visualized with correlatively with STEM and small angle X-ray scattering (SAXS). Samples were successfully characterized using both techniques, and minimal visual damage was induced during data acquisition. This work is the first to demonstrate the potential for bone to be investigated correlatively using both STEM and SAXS. Secondly, this work is the first to employ a dual-beam plasma FIB (PFIB) equipped with a scanning electron microscope (SEM), to investigate bone tissue across the mesoscale. This equipment enables large volume three-dimensional (3D) imaging at nanoscale resolution across larger mesoscale volumes. This thesis aimed to reduce ion beam-based artifacts, which presents as curtain-like features by adjusting the composition of protective capping layers. Subsequently, large volume tomograms of bone tissue were acquired, demonstrating the effectiveness of the PFIB to reveal mesoscale features including the cellular network of bone tissue. Overall, this thesis has developed methods that allow for the application of advanced microscopy techniques to enhance the understanding of bone tissue across the nanoscale and mesoscale. / Thesis / Master of Applied Science (MASc) / Bone tissue has a unique structure that perplexes both biologists and materials scientists. The hierarchical structure of bone has garnered the interest of materials scientists since the body’s skeletal strength and toughness are governed by the nanoscale (millionth of centimetres) to macroscale (centimeters) organization of bone. In this work, the intricate organization of bone is investigated using advanced electron and ion beam microscopy techniques, which achieve high-resolution imaging of bone structure. Firstly, this work developed a sample preparation workflow to correlate electron and X-ray imaging of the same bone tissue. Secondly, this work was the first to apply serial-sectioning plasma focused ion beam tomography to human bone tissue to investigate its structure at high resolution across micron-sized volumes. Here, previously unexplored methodologies to image bone are demonstrated with the hopes of applying such techniques to investigate healthy and pathological bone tissue in the future.

Materials with three-dimensional (3D) hierarchical architectures exhibit attractive mechanical, energy conversion and thermal radiative cooling properties not found in their bulk counterparts. However, implementation of hierarchically structured 3D transition metal dichalcogenides (TMDs) is widely deemed not possible, by the lack of manufacturing solutions that overcome the hierarchy, quality, and scalability dilemma. Here we report dewetting-driven destabilization (DDD) process that enables simple, template-free, high throughput printing of 3D architected MoS2 Foam with hierarchy spanning seven orders of magnitude — from angstroms to centimeters. Although extremely simple, our manufacturing process combines electrohydrodynamic printing with dewetting-induced-patterning. This technique can be applied to a range of dissimilar twodimensional (2D) layered materials, including Ti3C2Tx MXene and reduced graphene oxide (rGO). The deposited MoS2 Foam achieves amplification of resilience and conductivity. It constructs hierarchically porous and spatially interconnected networks for both ions and electrons transfer. We further demonstrate the 3D MoS2 architected foam as high-performance anodes with an otherwise unachievable combination of a 99% battery yield, a dynamic recovery (up to 85%) to withstand excessive volume expansion, a strain-induced reduction in diffusion barrier (0.2 eV), and improved electron transport abilities across the entire structure. The result is the high Li-ion charge storage capacity with robust cycling stability at a bulk scale (~3.5 mg/cm2) and under a high current density (10,000 mA/g). The outstanding electrochemical performance arises from the architected structure-induced pseudocapacitive energy storage mechanism based on the redox reaction of Mo, rather than the traditional conversion reaction. Notably, the performance achieved is on par with or surpasses state-of-the-art anodes made of black phosphorus composites, Si-graphene and mesoporous graphene particle anodes, while the technique offers an evaporation-like simplicity for industrial scalability. This work is foundational, and the developed DDD process opens a new sight to manufacture structurally robust, multifunctional hierarchical structures from 2D materials. Given the high adjustability of synthesis conditions and a wide variety of 2D materials, we anticipate previously unattainable possibilities in the energy storage, flexible electronics, catalysis, separation and drug delivery.

As a special subset of ad hoc networks, airborne networks aim to provide efficient network access for airborne and ground assets in a tactical environment. Conventional ad hoc routing protocols face some difficulties in such networks. First, significant overhead may be generated due to the high node mobility and dramatic topology changes. Second, temporary link failure may abort the delivery of a packet in some intermediate router. In this thesis, we propose a cluster-based reactive routing protocol to alleviate these problems. Our solution takes advantage of mesh routers installed in unmanned aerial vehicles or aircraft capable of hovering, when such airborne assets are available. As those mesh points usually have relatively stable connections among themselves, they play the role of cluster heads, forming a hierarchical routing structure. A simple self-organizing rule is introduced in cluster management to limit the cluster control overhead and route discovery flooding. In addition, a disruption tolerant mechanism (DTM) is deployed in the routing protocol to increase resilience to temporary link or node failure. The DTM utilizes the location, bearing and speed information provided by each node and intelligently maintains a buffer of packets that cannot be immediately delivered. If a temporary link failure occurs in the intermediate router during delivery, the packet is then buffered in that router up to a maximum time-to-live. The DTM also keeps track of link changes and tries to deliver the message as soon as a new path toward the destination is found. If the buffered messages are about to time out and the destination is still unreachable, the DTM still makes an effort to deliver the packet to another router with higher probability of eventually reaching the destination. This thesis also presents an implementation of the proposed solution in the ns-2 network simulator. The conventional Ad hoc On-Demand Distance Vector (AODV) routing protocol is adopted as the base model in the implementation. A mesh router model is programmed with two wireless interfaces. One of the interfaces is utilized to exchange routing information and packets with cluster members; the other is used to communicate with other mesh routers. This model is then installed on top of the AODV routing protocol and forms the hierarchical routing structure. The traditional AODV messages, including RREQ, RREP and HELLO, and routing tables are modified to support additional location information. Finally, the DTM is programmed and added to the AODV buffer management. The objective of this research is to use a mesh structure and DTM to improve the reliability and performance of airborne networks. The metrics of throughput and routing overhead are taken into consideration. The simulation results demonstrate that the proposed solution satisfies our research objectives. It achieves better performance than the conventional AODV, but introduces little overhead. The mesh structure can effectively adapt to high mobility, dynamic topology and different routing capabilities. The DTM provides a sophisticated way to maintain the buffer and mitigates the impact of intermittent links. / Master of Science

<p>Abstract</p><p>Organizational structures are surrounding the entire businesses and are essential for the functionality of an organization. The importance of a structure that satisfies and encourages the staff in the success of the organization to do a god job reflects on the organization’s success.</p><p>There are many different kinds of people and behaviours in the world, which makes the world we live in very complex and diversified. The perceptions of one human being, living in Europe, most likely aren’t the same as the perceptions of one person living on the other side of the globe. This difference between people all over the world also diversifies the organizations, which consists of these people. Different behaviour and organization structures are preferred by different organizations. This fact makes it difficult to operate an organization that is expanding to operate between national boarders.</p><p>The difficulties in moving to new nations and meeting new cultures leads to many problems. How will an organization that operates over national boarders adopt to the different countries involved? This thesis will examine the difficulties for these kinds of problems and how they should minimize possible problems that might occur through internationalization. The main question in this thesis will look at exactly how the transformation to go from one organizational structure to another in a Multinational corporations.</p><p>For a further analyse of the problem, one organization in an expanding situation will be examined. The organization that will be analysed is LG Electronics, which is a Multinational Enterprise organization that operates in several countries. The LG Electronics is an organization from South Korea which in Sweden has an IT-division that has worked as an experiment, in an attempt to minimize the problems that might occur when different organization cultures starts to work with each other.</p><p>The thesis will be strengthened mainly through background and organizational preferences information about differences between nations and the nations that act as the host and the home country for the organization, the two different structures involved and a list of different types of Multinational organizations. To examine the situation in LG Electronics interviews with two different purposes will be done, one with investigational purpose and one with informational purpose.</p><p>Keywords</p><p>Culture, Organization structure, Multinational Enterprises, Matrix structure, Hierarchical structure, Organizational change, Transformation, Host country, Home country</p>

Abstract Organizational structures are surrounding the entire businesses and are essential for the functionality of an organization. The importance of a structure that satisfies and encourages the staff in the success of the organization to do a god job reflects on the organization’s success. There are many different kinds of people and behaviours in the world, which makes the world we live in very complex and diversified. The perceptions of one human being, living in Europe, most likely aren’t the same as the perceptions of one person living on the other side of the globe. This difference between people all over the world also diversifies the organizations, which consists of these people. Different behaviour and organization structures are preferred by different organizations. This fact makes it difficult to operate an organization that is expanding to operate between national boarders. The difficulties in moving to new nations and meeting new cultures leads to many problems. How will an organization that operates over national boarders adopt to the different countries involved? This thesis will examine the difficulties for these kinds of problems and how they should minimize possible problems that might occur through internationalization. The main question in this thesis will look at exactly how the transformation to go from one organizational structure to another in a Multinational corporations. For a further analyse of the problem, one organization in an expanding situation will be examined. The organization that will be analysed is LG Electronics, which is a Multinational Enterprise organization that operates in several countries. The LG Electronics is an organization from South Korea which in Sweden has an IT-division that has worked as an experiment, in an attempt to minimize the problems that might occur when different organization cultures starts to work with each other. The thesis will be strengthened mainly through background and organizational preferences information about differences between nations and the nations that act as the host and the home country for the organization, the two different structures involved and a list of different types of Multinational organizations. To examine the situation in LG Electronics interviews with two different purposes will be done, one with investigational purpose and one with informational purpose. Keywords Culture, Organization structure, Multinational Enterprises, Matrix structure, Hierarchical structure, Organizational change, Transformation, Host country, Home country