Dissertations / Theses on the topic 'Communication in science – data processing'

Over the last few years 3D avatar virtual worlds (AVW) have emerged on the Internet. These are computer generated, multi-user, graphical spaces within which people meet, form social groups and interact with each other in real time, typically through the exchange of text or audio messages. Each user is represented within the space by a digital image known as an avatar, which is usually humanoid in form, and is predominantly under the control of the person it represents. This thesisd escribesa creativep roject that is concernedw ith aspectso f social communication between users of "Ws. In particular, an avatar is designed that is capable of performing body language, and a set of useful gestures are implemented that support aspects of social interaction and integrate with verbal discourse in a meaningful way. In addition to this, a number of scenic properties are derived that enable better comprehension of the non verbal communication, e. g. spatial arrangement, camera position and lighting effects. The research consists of a number of interrelated design activities which include reviewing the literature on avatar design in order to locate goals and variety of the project, therefore building on the on the work of others; a comparative review of three popular 3D AVWs to explore the design problem; a study that aims to gain an understanding of the social dynamics involved; the adaptation of a diagrammatic technique for the purpose of modelling social interaction; the development of 2D and 3D prototype techniques exploring the application of the social interaction modelling technique; a body of creative work developing ideas for conveying non verbal communication and the appraisal of the effectiveness of this creative work. The research contributes to the field of avatar design in a number of ways. Firstly, it develops our understanding of social dynamics in virtual worlds. Secondly, it postulates modes of non verbal communication for both individuals and social groups that supports multi-participatory social discourse. Additionally, a number of useful research techniques have been devised, such as a linear diagramming technique that can be used to represent the structure of conversation thereby facilitating the exploration and understanding of the dynamics of AVW social discourse. The work is of interest to those working in the field of avatar and multi-user virtual world design. It may also be of interest to anyone thinking of using an avatar virtual world for the application of collaborative leaming, collaborative games and conferencing.

Artificial agents and avatars are designed with a large variety of face and body configurations. Some of these (such as virtual characters in films) may be highly realistic and human-like, while others (such as social robots) have considerably more limited expressive means. In both cases, human motion serves as the model and inspiration for the non-verbal behavior displayed. This thesis focuses on increasing the expressive capacities of artificial agents and avatars using two main strategies: 1) improving the automatic capturing of the most communicative areas for human communication, namely the face and the fingers, and 2) increasing communication clarity by proposing novel ways of eliciting clear and readable non-verbal behavior. The first part of the thesis covers automatic methods for capturing and processing motion data. In paper A, we propose a novel dual sensor method for capturing hands and fingers using optical motion capture in combination with low-cost instrumented gloves. The approach circumvents the main problems with marker-based systems and glove-based systems, and it is demonstrated and evaluated on a key-word signing avatar. In paper B, we propose a robust method for automatic labeling of sparse, non-rigid motion capture marker sets, and we evaluate it on a variety of marker configurations for finger and facial capture. In paper C, we propose an automatic method for annotating hand gestures using Hierarchical Hidden Markov Models (HHMMs). The second part of the thesis covers studies on creating and evaluating multimodal databases with clear and exaggerated motion. The main idea is that this type of motion is appropriate for agents under certain communicative situations (such as noisy environments) or for agents with reduced expressive degrees of freedom (such as humanoid robots). In paper D, we record motion capture data for a virtual talking head with variable articulation style (normal-to-over articulated). In paper E, we use techniques from mime acting to generate clear non-verbal expressions custom tailored for three agent embodiments (face-and-body, face-only and body-only).

QC 20171127

Networking technology is connecting more and more people around the world. It has become an essential part of our daily life. For this connectivity to be seamless, networks need to be fast. Nonetheless, rapid growth in network traffic and variety of communication protocols overwhelms the Central Processing Units (CPUs) processing packets in the networks. Existing solutions to this problem such as ASIC, FPGA, NPU, and TOE are not cost effective and easy to manage because they require special hardware and custom configurations. This thesis approaches the problem differently by offloading the network processing to off-the-shelf Graphic Processing Units (GPUs). The thesis's primary goal is to find out how the GPUs should be used for the offloading. The thesis follows the case study approach and the selected case studies are layer 2 Bloom filter forwarding and flow lookup in Openflow switch. Implementation alternatives and evaluation methodology are proposed for both of the case studies. Then, the prototype implementation for comparing between traditional CPU-only and GPU-offloading approach is developed and evaluated. The primary findings from this work are criteria of network processing functions suitable for GPU offloading and tradeoffs involved. The criteria are no inter-packet dependency, similar processing flows for all packets, and within-packet parallel processing opportunity. This offloading trades higher latency and memory consumption for higher throughput.
Nätverksteknik ansluter fler och fler människor runt om i världen. Det har blivit en viktig del av vårt dagliga liv. För att denna anslutning skall vara sömlös, måste nätet vara snabbt. Den snabba tillväxten i nätverkstrafiken och olika kommunikationsprotokoll sätter stora krav på processorer som hanterar all trafik. Befintliga lösningar på detta problem, t.ex. ASIC, FPGA, NPU, och TOE är varken kostnadseffektivt eller lätta att hantera, eftersom de kräver speciell hårdvara och anpassade konfigurationer. Denna avhandling angriper problemet på ett annat sätt genom att avlasta nätverks processningen till grafikprocessorer som sitter i vanliga pc-grafikkort. Avhandlingen främsta mål är att ta reda på hur GPU bör användas för detta. Avhandlingen följer fallstudie modell och de valda fallen är lager 2 Bloom filter forwardering och ``flow lookup'' i Openflow switch. Implementerings alternativ och utvärderingsmetodik föreslås för både fallstudierna. Sedan utvecklas och utvärderas en prototyp för att jämföra mellan traditionell CPU- och GPU-offload. Det primära resultatet från detta arbete utgör kriterier för nätvärksprocessfunktioner lämpade för GPU offload och vilka kompromisser som måste göras. Kriterier är inget inter-paket beroende, liknande processflöde för alla paket. och möjlighet att köra fler processer på ett paket paralellt. GPU offloading ger ökad fördröjning och minneskonsumption till förmån för högre troughput.

A new type of software, termed a "group editor", allows multiple users to create and simultaneously edit a single document; this software has ostensibly been developed to increase efficiency in co-authoring environments where users may not be co-located. However, questions as to the effectiveness of this type of communication aid, which is a member of the "groupware" family of tools used for some types of computer supported cooperative work, remain. Particularly, there has been very little objective data on any group editor because of the problems inherent in evaluating writing, as well as due to the few examples of group editors that exist. A method was developed to examine the effect of using a particular group editor, Aspectsâ ¢ from Group Technologies in Arlington, Va., in conjunction with several communication media, on a simple dyad writing task. Six dyads of college students familiar with journalistic writing were matched on attributes of dominance and writing ability and were asked to write short news articles based on short video clips in a balanced two factor within-subject analysis of variance design. Six conditions were tested based on communication media: audio only, audio plus video, and face-to-face; each of these with and without the availability of the group editor. Constraints inherent in the task attempted to enforce consistent document quality levels, measured by grammatical quality and content quality (correctness of infonnation and chronological sequencing). Time to complete the articles was used as a measure of efficiency, independent from quality due to the consistent quality levels of the resulting work. Results from the time data indicated a significant effect of communication media, with the face-to-face conditions taking significantly less time to complete than either of the other media alternatives. Grammatical quality of the written articles was found to be of consistent high quality by way of computerized grammar checker. Content quality of the documents did not significantly differ for any of the conditions. A supplemental Latin square analysis showed additional significant differences in time to complete for trial means (a practice effect) and team differences. Further, significantly less variance was found in certain conditions which had the group editor than in other conditions which did not. Subjective data obtained from questionnaires supported these results and additional1y showed that subjects significantly preferred trials with the group editor and considered then more productive. The face-to-face conditions may have been more efficient due to the nature of the task or due to increased communication structure within dyads due to practice with the group editor. The significant effect of Team Differences may have been due to consistent style differences between dyads that affected efficiency levels. The decreased variability in time to complete in certain group editor conditions may have been due to increased communication structure in these conditions, or perhaps due to leveling effects of group writing as opposed to individual writing with team member aid. These hypotheses need to be tested with further study, and generalizability of the experimental task conditions and results from this particular group editor need to be established as well face-to-face conditions clearly resulted in the most efficient performance on this task. The results obtained concerning the group editor suggest possible efficiency or consistency benefits from the use of group editors by co-authoring persons when face-to-face communication is not practical. Perhaps group editors will become a useful method for surrogate travel for persons with disabilities.
Master of Science

Three quantum cryptographic protocols of multiuser quantum networks with embedded authentication, allowing quantum key distribution or quantum direct communication, are discussed in this work. The security of the protocols against different types of attacks is analysed with a focus on various impersonation attacks and the man-in-the-middle attack. On the basis of the security analyses several improvements are suggested and implemented in order to adjust the investigated vulnerabilities. Furthermore, the impact of the eavesdropping test procedure on impersonation attacks is outlined. The framework of a general eavesdropping test is proposed to provide additional protection against security risks in impersonation attacks.
In der Diplomarbeit werden drei verschiedene quantenkryptographische Protokolle mit dem Schwerpunkt auf authentifizierten Quantennetzwerken analysiert. Die Sicherheit der Protokolle gegenüber verschiedenen Angriffen wird untersucht, wobei der Fokus auf kompletten Personifikationsattacken („impersonation attacks“) liegt. Auf Basis der Sicherheitsanalyse und den Netzwerkanforderungen werden entsprechende Verbesserungen vorgeschlagen. Um die Gefahr von Personifikationen realistisch abschätzen zu können, wird außerdem der Einfluss des Testablaufs analysiert. Um zusätzlichen Schutz gegen Personifikationsattacken zu gewährleisten, werden die Rahmenbedingungen für eine allgemeine Testspezifikation festgelegt.

The constantly growing capacity of reconfigurable devices allows simultaneous execution of complex applications on those devices. The mere diversity of applications deems it impossible to design an interconnection network matching the requirements of every possible application perfectly, leading to suboptimal performance in many cases. However, the architecture of the interconnection network is not the only aspect affecting performance of communication. The resource manager places applications on the device and therefore influences latency between communicating partners and overall network load. Communication protocols affect performance by introducing data and processing overhead putting higher load on the network and increasing resource demand. Approaching communication holistically not only considers the architecture of the interconnect, but communication-aware resource management, communication protocols and resource usage just as well. Incorporation of different parts of a reconfigurable system during design- and runtime and optimizing them with respect to communication demand results in more resource efficient communication. Extensive evaluation shows enhanced performance and flexibility, if communication on reconfigurable devices is regarded in a holistic fashion.
Die Leistungsfähigkeit rekonfigurierbarer Rechensysteme steigt kontinuierlich und ermöglicht damit die parallele Ausführung von immer mehr und immer größeren Anwendungen. Die Vielfalt an Anwendungen macht es allerdings unmöglich ein optimales Kommunikationsnetzwerk zu entwickeln, welches die Anforderung jeder denkbaren Anwendung berücksichtigt. Die Performanz des rekonfigurierbaren Rechensystems sinkt. Das Kommunikationsnetzwerk ist jedoch nicht der einzige Teil des Systems, der Einfluss auf die Kommunikation- sperformanz nimmt. Die Ressourcenverwaltung des Systems beeinflusst durch die Platzierung der Anwendungen die Latenz zwischen Kommunikationspartnern und die Kommunikationslast im Netzwerk. Kommunikationsprotokolle beeinträchtigen die Performanz der Kommunikation durch Daten und Rechen- overhead, die ebenso zu erhöhter Netzwerklast sowie Ressourcenanforderungen führen. In einem ganzheitlichen Kommunikationsansatz wird nicht nur das Kommunikationsnetzwerk berücksichtigt, sondern außerdem Ressourcenverwaltung, Kommunikationsprotokolle und die anderweitige Verwendung vorhandener, temporär ungenutzter Kommunikationsressourcen. Durch Einbeziehung dieser Aspekte während Entwurfs- und Laufzeit und durch Optimierung unter Berücksichtigung der Kommunikationsanforderungen, wird eine ressourceneneffizien tere Kommunikation erreicht. Ausführliche Evaluationen zeigen, dass eine ganzheitliche Betrachtung von Kommunikationsfaktoren, Verbesserungen von Performanz und Flexibilität erzielt.

Seven to ten percent of the energy used globally goes towards powering information and communications technology (ICT): the global data- and telecommunications network, the private and commercial datacenters it supports, and the 19 billion electronic devices around the globe it interconnects, through which we communicate, and access and produce information. As bandwidth and data rates increase, so does the volume of traffic, as well as the absolute amount of new information digitized and uploaded onto the Net and into the cloud each second. Words like gigabit and terabyte were needless fifteen years ago in the public arena; now, they are common phrases. As people use their networked devices to do more, to access more, to send more, and to connect more, they use more energy--not only in their own devices, but also throughout the ICT. While there are many endeavors focused on individual low-power devices, few are examining broad strategies that cross the many boundaries of separate concerns within the ICT; also, few are assessing the impact of specific strategies on the global energy supply: at a global scale. This work examines the energy savings of several such strategies; it also assesses their efficacy in reducing energy consumption, both within specific networks and within the larger ICT. All of these strategies save energy by reducing the work done by the system as a whole on behalf of a single user, often by exploiting commonalities among what many users around the globe are also doing to amortize the costs.
Ph. D.

Load distribution problems in distributed computing networks have attracted much attention in the literature. A major objective in these studies is to distribute the processing load so as to minimize the time of processing of the entire load. In general, the processing load can be indivisible or divisible. An indivisible load has to be processed in its entirety on a single processor. On the other hand, a divisible load can be partitioned and processed on more than one processor. Divisible loads are either modularly divisible or arbitrarily divisible. Modularly divisible loads can be divided into pre-defined modules and cannot be further sub-divided. Further, precedence relations between modules may exist. Arbitrarily divisible loads can be divided into several fractions of arbitrary lengths which usually do not have any precedence relations. Such type of loads are characterized by their large volume and the property that each data element requires an identical and independent processing. One of the important problems here is to obtain an optimal load distribution, which minimizes the processing time when the distribution is subject to communication delays in the interconnecting links. A specific application in which such loads are encountered is in edge-detection of images. Here the given image frame can be arbitrarily divided into many sub-frames and each of these can be independently processed. Other applications include processing of massive experimental data. The problems associated with the distribution of such arbitrarily divisible loads are usually analysed in the framework of what is known as divisible job theory. The research work reported in this thesis is a contribution in the area of distributing arbitrarily divisible loads in distributed computing systems subject to communication delays. The main objective in this work is to design and analyseload distribution strategies to minimize the processing time of the entire load in a given network. Two types of networks are considered, namely (i) single-level tree (or star) network and (ii) linear network. In both the networks we assume that there is a non-zero delay associated with load transfer. Further, the processors in the network may or may not be equipped with front-ends (Le., communication co-processors). The main contributions in this thesis are summarized below. First, a mathematical formulation of the load distribution problem in single-level tree and linear networks is presented. In both the networks, it is assumed that there are (m +1) processors and m communication links. In the case of single-level tree networks, the load to be processed is assumed to originate at the root processor, which divides the load into (m +1) fractions, keeps its own share of the load for processing, and distributes the rest to the child processors one at a time and in a fixed sequence. In all the earlier studies in the literature, it had been assumed that for a load distribution to be optimal, it should be such that all the processors must stop computing at the same time. In this thesis, it is shown that this assumption is in general not true, and holds only for a restricted class of single-level tree networks which satisfy a certain condition. The concept of an equivalent network is introduced to obtain a precise formulation of this condition in terms of the processor and link speed parameters. It is shown that this condition can be used to identify processor-link pairs which can be eliminated from a given network (i.e., these processors need not be given any computational load) without degrading its time performance. It is proved that the resultant reduced network (a network from which these inefficient processor-link pairs have been removed) gives the optimal time performance if and only if the load distribution is such that all the processors stop computing at the same time instant. These results are first proved for the case when the root processor is equipped with a front-end and then extended to the case when it is not. In the latter case, an additional condition, between the speed of the root processor and the speed of each of the links, to be satisfied by the network is specified. An optimal sequence for applying these conditions is also obtained. In the case of linear networks the processing load is assumed to originate at the processor situated at one end of the network. Each processor in the network keeps its own load fraction for computing and transmits the rest to its successor. Here too, in all the earlier studies in the literature, it has been assumed that for the processing time to be a minimum, the load distribution must be such that all the processors must stop computing at the same instant in time. Though this condition has been proved by others to be both necessary and sufficient, a different and more rigorous proof, similar to the case of single-level tree network, is presented here. Finally, the effect of inaccurate modelling on the processing time and on the above conditions are discussed through an illustrative example and it is shown that the model adopted in this thesis gives reasonably accurate results. In the case of single-level tree networks, so far it has been assumed that the root processor distributes the processing load in a fixed sequence. However, since there are m child processors, a total of m! different sequences of load distribution are possible. Using the closed-form derived for the processing time, it is proved here that the optimal sequence of load distribution follows the decreasing order of link speeds. Further, if physical rearrangement of processors and links is allowed, then it is shown that the optimal arrangement follows a decreasing order of link and processor speeds with the fastest processor at the root. The entire analysis is first done for the case when the root processor is equipped with a front-end, and then extended to the case when it is not. In the without front-end case, it is shown that the same optimal sequencing result holds. However, in an optimal arrangement, the root processor need not be the fastest. In this case an algorithm has been proposed for obtaining optimal arrangement. Illustrative examples are given for all the cases considered. Next, a new strategy of load distribution is proposed by which the processing time obtained in earlier studies can be further minimized. Here the load is distributed by the root processor to a child processor in more than one installment (instead of in a single installment) such that the processing time is further minimized. First; the case in which all the processors are equipped :tn front-ends is considered. Recursive equations are obtained for a heterogeneous network and these are solved for the special case of a homogeneous network (having identical processors and identical links). Using this closed-form solution, the ultimate limits of performance are explored through an asymptotic analysis with respect to the number of installments and number of processors in the network. Trade-off relationships between the number of installments and the number of processors in the network are also presented. These results are then extended to the case when the processors are not equipped with front-ends. Finally, the efficiency of this new strategy of load distribution is demonstrated by comparing it with the existing single-installment strategy in the literature. The multi-installment strategy explained above is then applied to linear net-As. Here, .the processing load is assumed to originate at one extreme end of the network, First the case when all the processors are equipped with front-ends is considered. Recursive equations for a heterogeneous network are obtained and these are solved for the special case of a homogeneous network. Using this closed form solution, an asymptotic analysis is performed with respect to the number of installments. However, the asymptotic results with respect to the number of processors was obtained computationally since analytical results could not be obtained. It is found that for a given network, once the number of installments is fixed, there is an optimum number of processors to be used in the network, beyond which the time performance degrades. Trade-off relationships between the number of installments and the number of processors is obtained. These results are then extended to the case when the processors are not equipped with front-ends. Comparisions with the existing single-installment strategy is also done. The single-installment strategy discussed in the literature has the disadvantage that the front-ends of the processors are not utilized efficiently in a linear network. This is due to the fact that a processor starts computing its own load fraction only after the entire load to be communicated through its front-end has been received. In this thesis, a new strategy is proposed in which a processor starts computing as soon as it receives its load fraction, simultaneously allowing its front-end to receive and transmit load to its successors. Recursive equations are developed and solved for the special case of a heterogeneous network in which the processors and links are arranged in the decreasing order of speeds. Further, it is shown that in this strategy, if the processing load originates in the interior of the network, the sequence of load distribution should- be such that the load should be first distributed to the side with a lesser number of processors. An expression for the optimal load origination point in the network is derived. A comparative study of this strategy with an earlier strategy is also presented. Finally, it is shown that even though the analysis is carried out for a special case of a heterogeneous network, this load distribution strategy can also be applied to a linear network in which the processors and links are arbitrarily arranged and still obtain a significant improvement in the time performance.

Load distribution problems in distributed computing networks have attracted much attention in the literature. A major objective in these studies is to distribute the processing load so as to minimize the time of processing of the entire load. In general, the processing load can be indivisible or divisible. An indivisible load has to be processed in its entirety on a single processor. On the other hand, a divisible load can be partitioned and processed on more than one processor. Divisible loads are either modularly divisible or arbitrarily divisible. Modularly divisible loads can be divided into pre-defined modules and cannot be further sub-divided. Further, precedence relations between modules may exist. Arbitrarily divisible loads can be divided into several fractions of arbitrary lengths which usually do not have any precedence relations. Such type of loads are characterized by their large volume and the property that each data element requires an identical and independent processing. One of the important problems here is to obtain an optimal load distribution, which minimizes the processing time when the distribution is subject to communication delays in the interconnecting links. A specific application in which such loads are encountered is in edge-detection of images. Here the given image frame can be arbitrarily divided into many sub-frames and each of these can be independently processed. Other applications include processing of massive experimental data. The problems associated with the distribution of such arbitrarily divisible loads are usually analysed in the framework of what is known as divisible job theory. The research work reported in this thesis is a contribution in the area of distributing arbitrarily divisible loads in distributed computing systems subject to communication delays. The main objective in this work is to design and analyseload distribution strategies to minimize the processing time of the entire load in a given network. Two types of networks are considered, namely (i) single-level tree (or star) network and (ii) linear network. In both the networks we assume that there is a non-zero delay associated with load transfer. Further, the processors in the network may or may not be equipped with front-ends (Le., communication co-processors). The main contributions in this thesis are summarized below. First, a mathematical formulation of the load distribution problem in single-level tree and linear networks is presented. In both the networks, it is assumed that there are (m +1) processors and m communication links. In the case of single-level tree networks, the load to be processed is assumed to originate at the root processor, which divides the load into (m +1) fractions, keeps its own share of the load for processing, and distributes the rest to the child processors one at a time and in a fixed sequence. In all the earlier studies in the literature, it had been assumed that for a load distribution to be optimal, it should be such that all the processors must stop computing at the same time. In this thesis, it is shown that this assumption is in general not true, and holds only for a restricted class of single-level tree networks which satisfy a certain condition. The concept of an equivalent network is introduced to obtain a precise formulation of this condition in terms of the processor and link speed parameters. It is shown that this condition can be used to identify processor-link pairs which can be eliminated from a given network (i.e., these processors need not be given any computational load) without degrading its time performance. It is proved that the resultant reduced network (a network from which these inefficient processor-link pairs have been removed) gives the optimal time performance if and only if the load distribution is such that all the processors stop computing at the same time instant. These results are first proved for the case when the root processor is equipped with a front-end and then extended to the case when it is not. In the latter case, an additional condition, between the speed of the root processor and the speed of each of the links, to be satisfied by the network is specified. An optimal sequence for applying these conditions is also obtained. In the case of linear networks the processing load is assumed to originate at the processor situated at one end of the network. Each processor in the network keeps its own load fraction for computing and transmits the rest to its successor. Here too, in all the earlier studies in the literature, it has been assumed that for the processing time to be a minimum, the load distribution must be such that all the processors must stop computing at the same instant in time. Though this condition has been proved by others to be both necessary and sufficient, a different and more rigorous proof, similar to the case of single-level tree network, is presented here. Finally, the effect of inaccurate modelling on the processing time and on the above conditions are discussed through an illustrative example and it is shown that the model adopted in this thesis gives reasonably accurate results. In the case of single-level tree networks, so far it has been assumed that the root processor distributes the processing load in a fixed sequence. However, since there are m child processors, a total of m! different sequences of load distribution are possible. Using the closed-form derived for the processing time, it is proved here that the optimal sequence of load distribution follows the decreasing order of link speeds. Further, if physical rearrangement of processors and links is allowed, then it is shown that the optimal arrangement follows a decreasing order of link and processor speeds with the fastest processor at the root. The entire analysis is first done for the case when the root processor is equipped with a front-end, and then extended to the case when it is not. In the without front-end case, it is shown that the same optimal sequencing result holds. However, in an optimal arrangement, the root processor need not be the fastest. In this case an algorithm has been proposed for obtaining optimal arrangement. Illustrative examples are given for all the cases considered. Next, a new strategy of load distribution is proposed by which the processing time obtained in earlier studies can be further minimized. Here the load is distributed by the root processor to a child processor in more than one installment (instead of in a single installment) such that the processing time is further minimized. First; the case in which all the processors are equipped :tn front-ends is considered. Recursive equations are obtained for a heterogeneous network and these are solved for the special case of a homogeneous network (having identical processors and identical links). Using this closed-form solution, the ultimate limits of performance are explored through an asymptotic analysis with respect to the number of installments and number of processors in the network. Trade-off relationships between the number of installments and the number of processors in the network are also presented. These results are then extended to the case when the processors are not equipped with front-ends. Finally, the efficiency of this new strategy of load distribution is demonstrated by comparing it with the existing single-installment strategy in the literature. The multi-installment strategy explained above is then applied to linear net-As. Here, .the processing load is assumed to originate at one extreme end of the network, First the case when all the processors are equipped with front-ends is considered. Recursive equations for a heterogeneous network are obtained and these are solved for the special case of a homogeneous network. Using this closed form solution, an asymptotic analysis is performed with respect to the number of installments. However, the asymptotic results with respect to the number of processors was obtained computationally since analytical results could not be obtained. It is found that for a given network, once the number of installments is fixed, there is an optimum number of processors to be used in the network, beyond which the time performance degrades. Trade-off relationships between the number of installments and the number of processors is obtained. These results are then extended to the case when the processors are not equipped with front-ends. Comparisions with the existing single-installment strategy is also done. The single-installment strategy discussed in the literature has the disadvantage that the front-ends of the processors are not utilized efficiently in a linear network. This is due to the fact that a processor starts computing its own load fraction only after the entire load to be communicated through its front-end has been received. In this thesis, a new strategy is proposed in which a processor starts computing as soon as it receives its load fraction, simultaneously allowing its front-end to receive and transmit load to its successors. Recursive equations are developed and solved for the special case of a heterogeneous network in which the processors and links are arranged in the decreasing order of speeds. Further, it is shown that in this strategy, if the processing load originates in the interior of the network, the sequence of load distribution should- be such that the load should be first distributed to the side with a lesser number of processors. An expression for the optimal load origination point in the network is derived. A comparative study of this strategy with an earlier strategy is also presented. Finally, it is shown that even though the analysis is carried out for a special case of a heterogeneous network, this load distribution strategy can also be applied to a linear network in which the processors and links are arbitrarily arranged and still obtain a significant improvement in the time performance.

STG decomposition is a promising approach to tackle the complexity problems arising in logic synthesis of speed independent circuits, a robust asynchronous (i.e. clockless) circuit type. Unfortunately, STG decomposition can result in components that in isolation have irreducible CSC conflicts. Generalising earlier work, it is shown how to resolve such conflicts by introducing internal communication between the components via structural techniques only.
STG-Dekomposition ist ein bewährter Ansatz zur Bewältigung der Komplexitätsprobleme bei der Logiksynthese von SI (speed independent) Schaltungen – ein robuster asynchroner (d.h. ohne Taktsignal arbeitender digitaler) Schaltungstyp. Allerdings können dabei Komponenten mit irreduziblen CSC-Konflikten entstehen. Durch Verallgemeinerung früherer Arbeiten wird gezeigt, wie solche Konflikte durch Einführung interner Kommunikation zwischen den Komponenten gelöst werden können, und zwar ausschließlich durch Verwendung an der Graphenstruktur ansetzender Verfahren.

Nowadays, with the rapid development of GPS-equipped mobile devices, location-based social networks have been emerging to bridge the gap between the physical world and online social networking services. Various types of data, such as personal locations, check-ins, microblogs and social relations, have been available in location-based social networks. Efficiently managing and analyzing such data to meet users' daily query requirements become a challenging task. Among all the existing works in location-based social networks, group query is one of the most important research topics. In this thesis, we investigate query techniques for location-based services in social networking applications. Specifically, considering a location-based social network, we study spatial-aware interest group queries, geo-social {dollar}k{dollar}-cover group queries, and social-aware ridesharing group queries. Firstly, we study the spatial-aware interest group queries in location-based social networks. Recently, most of the location-based social networks release check-in services that allow users to share their visiting locations with their friends. These locations, considered as spatial objects, are usually associated with a few tags that describe the features of those locations. Utilizing such information, we propose a new type of \emph{Spatial-aware Interest Group} (SIG) query that retrieves a user group of size {dollar}k{dollar} where each user is interested in the query keywords and the users are close to each other in the Euclidean space. We prove this query problem is NP-complete, and develop two efficient algorithms IOAIR and DOAIR based on the IR-tree for the processing of SIG queries. We also validate the performance efficiency of the proposed query processing algorithms by empirical evaluation. Secondly, we study the problem of geo-social {dollar}k{dollar}-cover group queries for collaborative spatial computing. In this problem, we propose a novel type of geo-social queries, called \emph{Geo-Social K-Cover Group} (GSKCG) query, which is based on spatial containment and a new modeling of social relationships. Intuitively, given a set of spatial query points and an underlying social network, a GSKCG query finds a minimum user group in which the members satisfy certain social relationship and their associated regions can jointly cover all the query points. Albeit its practical usefulness, the GSKCG query problem is NP-complete. We consequently explore a set of effective pruning strategies to derive an efficient algorithm for finding the optimal solution. Moreover, we design a novel index structure tailored to our problem to further accelerate query processing. Extensive experiments demonstrate that our algorithm achieves desirable performance on real-life datasets. Thirdly, we study the problem of social-aware ridesharing group queries. With the deep penetration of smartphones and geo-locating devices, ridesharing is envisioned as a promising solution to transportation-related problems such as congestion and air pollution for metropolitan cities. Despite the potential to provide significant societal and environmental benefits, ridesharing has not so far been as popular as expected. Notable barriers include the social discomfort and safety concerns when traveling with strangers. To overcome these barriers, in this thesis, we propose a new type of \emph{Social-aware Ridesharing Group} (SaRG) query which retrieves a group of riders by taking into account their social connections besides traditional spatial proximities. Because the SaRG query problem is NP-hard, we design an efficient algorithm with a set of powerful pruning techniques to tackle this problem. We also present several incremental strategies to accelerate the search speed by reducing the repeated computations. Moreover, we propose a novel index tailored to the proposed problem to further speed up the query processing. Experimental results on real datasets show that our proposed algorithms achieve desirable performance. The works of this thesis show that the group query processing techniques are effective, which would facilitate the wider deployment of such query services in real applications

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xix, 183 p.; also includes graphics (some col.). Includes bibliographical references (p. 170-183). Available online via OhioLINK's ETD Center

Thesis (MTech (Information Technology))--Peninsula Technikon, 2004
Encryption was used whenever someone wanted to send a secret message to someone. The quality of the algorithm and key combination were the factors that ensured the strength of the system. However, until there were some automation one could not use complex methods for encryption because it simply took too long to encrypt and decrypt messages (even worse for images), manually. Optical technologies have recently been employed in encryption. Compared with traditional computer and electrical systems, optical technologies offer primarily two types of benefits, namely optical systems have an inherent capability for parallel processing, that is, rapid transmission of information, and information can be hidden in any of several dimensions, such as phase or spatial frequency. Optical systems therefore have an excellent capability for encoding information. In this project an image encryption technique was developed using exclusive-OR (XOR) operations in the optical domain before the captured image entered a digital computer network for further processing. A gray-level image of the object to be encrypted was converted a binary format and a pixel by pixel exclusive OR operation was performed on it with a random key-bit by making use of polarization encoding in LCD technology, before the encrypted binary image was detected by a CCD. The image may also be used as an input to a computer for comparison with a database. However, noise alters the encrypted bit and the value of the noisy encrypted bit is no longer binary. In this research the encryption techniques was evaluated and tested for applicability to encrypt and decrypt successfully. The noise performance was tested and compared. The technique was applied for image transmission over a wireless IP broadband link. Images (optical and thermal) captured from telemedicine application was transmitted and decrypted with reasonable success in this application.

De nos jours, les médias sociaux en ligne ont transformé notre façon de créer, de partager et d'accéder à l'information. Ces plateformes reposent sur de gigantesques réseaux favorisent le libre échange d'informations entre des centaines de millions de personnes à travers le monde entier, et cela de manière instantanée.Qu'ils soient en lien avec un évènement global ou en lien avec un évènement local, ces messages peuvent influencer une société et peuvent contenir des informations utiles pour la détection ou la prédiction de phénomènes du monde réel.Cependant, certains messages diffusés peuvent avoir un impact très négatif dans la vie réelle. Ces messages contenant une « infox » peuvent avoir des conséquences désastreuses.Pour éviter et anticiper ces situations dramatiques, suivre les rumeurs, éviter les mauvaises réputations, il est nécessaire d'étudier puis de modéliser la propagation de l'information.Or, la plupart des modèles de diffusion introduits reposent sur des hypothèses axiomatiques représentées par des modèles mathématiques. Par conséquent, ces modèles sont éloignés des comportements de diffusion des utilisateurs dans la mesure où ils n’intègrent pas les observations faites sur des cas concrets de diffusion. Dans nos travaux, nous étudions le phénomène de diffusion de l’information à deux échelles. À une échelle microscopique, nous avons observé les comportements de diffusion selon des traits de personnalité des utilisateurs en analysant les messages qu'ils publient en termes de sentiments et d'émotions. À une échelle macroscopique, nous avons analysé l'évolution du phénomène de diffusion en prenant en compte la dimension géographique des utilisateurs
Nowadays, online social media has transformed the way we create, share and access information. These platforms rely on gigantic networks that promote the free exchange of information between hundreds of millions of people around the world, and this instantly.Whether related to a global event or in connection with a local event, these messages may influence a society and may contain information useful for the detection or prediction of real-world phenomena.However, some broadcast messages can have a very negative impact in real life. These messages containing false information can have disastrous consequences.To avoid and anticipate these dramatic situations, follow rumors, avoid bad reputations, it is necessary to study and then model the propagation of information.However, most of the diffusion models introduced are based on axiomatic hypotheses represented by mathematical models. As a result, these models are far removed from the users' dissemination behaviors in that they do not incorporate observations made on concrete dissemination cases. In our work, we study the phenomenon of diffusion of information at two scales. On a microscopic scale, we observed diffusion behaviors based on the personality traits of users by analyzing the messages they post in terms of feelings and emotions. On a macroscopic scale, we analyzed the evolution of the diffusion phenomenon by taking into account the geographical dimension of the users

In this thesis, we use evolutionary robotics techniques to automatically design and synthesise

behaviour for groups of simulated and real robots. Our contribution will be on

the design of non-trivial individual and collective behaviour; decisions about solitary or

social behaviour will be temporal and they will be interdependent with communicative

acts. In particular, we study time-based decision-making in a social context: how the

experiences of robots unfold in time and how these experiences influence their interaction

with the rest of the group. We propose three experiments based on non-trivial real-world

cooperative scenarios. First, we study social cooperative categorisation; signalling and

communication evolve in a task where the cooperation among robots is not a priori required.

The communication and categorisation skills of the robots are co-evolved from

scratch, and the emerging time-dependent individual and social behaviour are successfully

tested on real robots. Second, we show on real hardware evidence of the success of evolved

neuro-controllers when controlling two autonomous robots that have to grip each other

(autonomously self-assemble). Our experiment constitutes the first fully evolved approach

on such a task that requires sophisticated and fine sensory-motor coordination, and it

highlights the minimal conditions to achieve assembly in autonomous robots by reducing

the assumptions a priori made by the experimenter to a functional minimum. Third, we

present the first work in the literature to deal with the design of homogeneous control

mechanisms for morphologically heterogeneous robots, that is, robots that do not share

the same hardware characteristics. We show how artificial evolution designs individual

behaviours and communication protocols that allow the cooperation between robots of

different types, by using dynamical neural networks that specialise on-line, depending on

the nature of the morphology of each robot. The experiments briefly described above

contribute to the advancement of the state of the art in evolving neuro-controllers for

collective robotics both from an application-oriented, engineering point of view, as well as

from a more theoretical point of view.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

In this project a collaboration multimedia toolkit, JSCMT (Java Synchronized Collaborative Multimedia Toolkit) was developed which is intended to connect a group of people located in different geographical locations who are working on the same project.

This research project examined the effects of participation in a six-month global service-learning program in the intercultural development of a group of students. The students under consideration herein participated in the 2009 program year of the Grace University EDGE Program, which took place in Mali, West Africa. The present research builds on and contributes to three primary areas of research: intercultural development, service-learning, and study abroad. As the literature in these areas revealed the lack of a consistent way to assess global service-learning, I tried a three-part method of assessment. First, the Intercultural Development Inventory formally measured growth in intercultural competence. Second, guided course-writing generated by the students was used to facilitate followup interviews of most participants, especially considering the intersections between IDI results and students' self-perceptions as reported in their papers. Third, the interviews were coded and explored for information related to the process of intercultural development. The participants, overall, demonstrated positive intercultural competence gains while undergoing a complex process involving the impetus for and experience of development, ultimately resulting in changed patterns of thought.

Two types of artificial neural networks, Multilayer Perceptron (MLP) and Self-organizing Feature Map (SOM), were employed to detect mastitis for robotic milking stations using the preprocessed data relating to the electrical conductivity and milk yield. The SOM was developed to classify the health status into three categories: healthy, moderately ill and severely ill. The clustering results were successfully evaluated and validated by using statistical techniques such as K-means clustering, ANOVA and Least Significant Difference. The result shows that the SOM could be used in the robotic milking stations as a detection model for mastitis. For developing MLP models, a new mastitis definition based on higher EC and lower quarter yield was created and Principle Components Analysis technique was adopted for addressing the problem of multi-colinearity existed in the data. Four MLPs with four combined datasets were developed and the results manifested that the PCA-based MLP model is superior to other non-PCA-based models in many respects such as less complexity, higher predictive accuracy. The overall correct classification rate (CCR), sensitivity and specificity of the model was 90.74 %, 86.90 and 91.36, respectively. We conclude that the PCA-based model developed here can improve the accuracy of prediction of mastitis by robotic milking stations.

The project, Spider III, presents architecture and protocol of a multi-agent-based internet distributed computing system, which provides a convenient development and execution environment for transparent task distribution, load balancing, and fault tolerance. Spider is an on going distribution computing project in the Department of Computer Science, California State University San Bernardino. It was first proposed as an object-oriented distributed system by Han-Sheng Yuh in his master's thesis in 1997. It has been further developed by Koping Wang in his master's project, of where he made large contribution and implemented the Spider II System.

Emergency workers comprise large professional groups like volunteer fire-fighters, police officers, emergency medical staff and so on. Their professions have to deal frequently with a considerable number of a combination of health and safety risk factors, which are often unavoidable. For example, workplace scenes demanding the intervention of emergency workers may be located in remote, difficult to access areas (mountains, sea, caves), and sometimes in extremely difficult weather conditions. Moreover, emergency workers must arrive very rapidly at the disaster scene at any time of the day or night, and there is always the possibility of car crashes or other transportation accidents on the journey to the disaster scene or to hospitals. Others examples are the industrial workplaces, which are inherently places with a high concentration of heavy machinery, fast handling equipments, high heat and pressure pipes, polluted and explosive areas where people work in a relatively small area. Therefore, in an environment where situational awareness and tactical decision making are critical elements to a successful operation, it is really important to have available efficient instruments to ensure the safety for all operators that work in the field. Despite the fact that a lot sophisticated solutions have been used for increasing request due to the growing need of safety concerns by the operators, the mission-critical environments are still considered high-risk environments with serious work safety related issues and higher accident rates than in other workplaces. This study focuses on the safety precautions in outdoor and indoor environments, safety communication and Personal Protective Equipment (PPE) and proposes solutions to ensure secure and reliable communications between forces deployed in the field and their dispatch center, which is often of decisive importance for the work of the emergency services, analyzing two different important case studies. Moreover, we have designed a control system intended as a platform for real-time information capable of monitoring, by means of camera and sensor data harvesting about people and vehicles movements. It provides automatic and semi-automatic risk prevention measures thanks to the work in progress on designing and implementing a first working prototype of sensor network based on RFID BAN. These capabilities are the topic of a larger research project that aims to find the optimal solution in terms of feasibility and practical implementation. To conclude our study, we have developed a indoor navigation system for mobile devices. The application is able to follow the user and it indicates the shortest path to achieve a specific destination. It uses only smartphone motion sensor and not requires the use of extra equipment. Moreover, thanks to an algorithm widely explained afterwards and the use of the gyroscope sensor rather than the compass, the mobile application ensure a very good orientation. The thesis is organized as following: - In the first chapter, to design a radio communication system both for health emergency services and Civil Protection services, different Professional Mobile Radio (PMR) standards was analized. PMR, also known as land mobile radio (LMR) in North America, are field radio communications systems which use portable, mobile, base station, and dispatch console radios. It has referred to a suite of radio mobile network tecnologies deployed for missioncritical users, which need high affordable communication system. In the specific, PMR networks provide radio services for closed user group, group call and push-to-talk, and call set-up times which are generally short compared with cellular system. In addition, they provide communications in extreme situations that might cause failures in other communications network, like 2G or 3G. As a result of the analysis of the main digital PMR standards (TETRA and DMR) used in European countries, we decided to use the DMR standard to design the radio network for 118 service in Sardinia and for Civil Protection service. DMR has been identified as the best solution, which grants cost saving, high coverage, spectral efficiency and simplicity in network configuration and it is well suitable in wide area with a low/medium density of traffic. - The second and third chapter of the thesis are focused on improvement of the safety of operators in a maritime cargo terminal. Hence, a new infrastructure of a maritime cargo terminal has been defined, using a control system for monitoring workplace safety. By combining, in the control system, the inputs from a Body Area Network (BAN) integrated in the safety equipment and from CCTV cameras, a human supervisor is able to achieve an accurate overview of the entire situation in terms of work safety and act accordingly when needed. In addition, we focused even on the design and implementation of a working prototype of an RFID-based BAN sensor network for actively monitoring and preventing workplace safety risks in the same industrial area. This first conceptual and technological analysis, together with the test implementation, is the forerunner of a complex monitoring system in development to be implemented both for the specific case and for any industrial environment. - The last chapter aims to describe an indoor navigation system developed for smartphone android. Specifically, it has been demonstrated how the use of a gyroscope sensor can brings more benefits respect to a compass sensor to get the best detected position. Nowadays, modern mobile devices, such as smartphones and PDAs in general, come to the market already equipped with sensors able to track them as they move, both in outdoor and indoor environment. The sensing technologies embedded in such devices make it ideal for a wide range of location-based services, such as navigation applications. An Inertial Navigation System (INS) uses motion and rotation sensors in order to determine the position, orientation, and velocity of a moving object/user without the need of external infrastructures. This is essential in an indoor environment where common localization systems, such as Global Positioning System (GPS), fail due to severe attenuation or obscuration of the satellite's signal. In inertial navigation systems, localization/ orientation estimation is source-independent. The user's position is calculated in relation to a known starting position using a dead reckoning algorithm and the orientation is usually provided by a digital compass embedded in the smartphone. A digital compass sensor provides the orientation of the device relative to the magnetic north of the earth. However, when it is used in indoor environments, like any magnetic device, it is affected by significant error caused by nearby ferrous materials, as well as local electromagnetic fields. Such errors seriously affect the performance and the accuracy of the system, thus the need to investigate any alternative orientation technique. In the specific, we have developed an early prototype of a pedestrian navigation system for indoor environments based on dead reckoning, 2D barcodes and data from accelerometers and magnetometers. All the sensing and computing technologies of our solution are available in common smartphones. The prototype has been further improved by a new algorithm described afterwards and now it is able to estimate the correct current position of the user, track him inside the building and provide the best path to achieve a specific destination.

Au fur et à mesure que la complexité s'accroit, il devient nécessaire de définir de nouvelles méthodes permettant de la gérer. Une des façons de maîtriser cette complexité est d'élever le niveau d'abstraction des spécifications en utilisant des langages de spécification systèmes. D'un autre côté, l'élévation du niveau d'abstraction augmente le fossé entre les concepts utilisés pour la spécification (processus communicants, communication abstraite) et ceux utilisés par les langages de description de matériel. Bien que ces langages soient bien adaptés à la spécification et la validation de systèmes complexes, les concepts qu'ils manipulent ne sont pas aisément transposables sur ceux des langages de description de matériels. Il est donc nécessaire de définir de nouvelles méthodes permettant une synthèse efficace à partir de spécifications systèmes. Le sujet de cette thèse est la présentation d'une approche de génération de code C et VHDL à partir de spécifications systèmes en SDL. Cette approche résout la principale difficulté rencontrée par les autres approches, à savoir la communication inter-processus. La communication SDL peut être traduite en VHDL en vue de la synthèse. Cela est rendu possible par l'utilisation d'une forme intermédiaire qui supporte un modèle de communication générale qui autorise la représentation pour la synthèse de la plupart des schémas de communication. Cette forme intermédiaire permet d'appliquer au système un ensemble d'étapes de raffinement pour obtenir la solution désirée. La principale étape de raffinement, appelée synthèse de la communication, détermine le protocole et les interfaces utilisés par les différents processus pour communiquer. La spécification raffinée peut être traduite en C et VHDL pour être utilisée par des outils du commerce. Nous illustrons la faisabilité de cette approche par une application à un système de télécommunication : le protocole TCP/IP sur ATM
As the system complexity grows there is a need for new methods to handle large system design. One way to manage that complexity is to rise the level of abstraction of the specifications by using system level description languages. On the other side, as the level of abstraction rise the gap between the concepts used for the specification at the system level (communication channels, interacting processes, data types) and those used for hardware synthesis becomes wider. Although these languages are well suited for the specification and validation of complex real time distributed systems, the concepts manipulated are not easy to map onto hardware description languages. It is thus necessary to defines methods for system level synthesis enabling efficient synthesis from system level specifications. The subject of this thesis is the presentation of a new approach of generation of C and VHDL code from system level specifications in SDL. This approach solves the main problem encountered by previous approach : inter process communications. SDL communication can be translated in VHDL for synthesis. This is achieved by the use of a powerful intermediate form that support the modelling for synthesis of a wide range of communication schemes. This intermediate form allows to apply to the system a set of transformations in order to obtain the desired solution. The main refinement step, called communication synthesis is aimed at fixing the protocol and interface used by the different processes to communicate. The refined specification can be translated in C and VHDL and synthesised by commercial tools. We illustrate the feasibility of this approach through an application to a telecommunication example : the TCP/IP over ATM protocol

Globally distributed software teams are widespread throughout industry. But finding reliable methods that can properly assess a team's activities is a real challenge. Methods such as surveys and manual coding of activities are too time consuming and are often unreliable. Recent advances in information retrieval and linguistics, however, suggest that automated and/or semi-automated text classification algorithms could be an effective way of finding differences in the communication patterns among individuals and groups. Communication among group members is frequent and generates a significant amount of data. Thus having a web-based tool that can automatically analyze the communication patterns among global software teams could lead to a better understanding of group performance. The goal of this thesis, therefore, is to compare automatic and semi-automatic measures of communication and evaluate their effectiveness in classifying different types of group activities that occur within a global software development project. In order to achieve this goal, we developed a web-based component that can be used to help clean and classify communication activities. The component was then used to compare different automated text classification techniques on various group activities to determine their effectiveness in correctly classifying data from a global software development team project.

Remote procedure call (RPC) and shared variable are communication abstractions which allow the various processes of a distributed program, often modelled as clients and servers, to communicate with one another across machine boundaries. A key requirement of the abstractions is to mask the machine and communication failures that may occur during the client-server communications. In practice, many distributed applications can inherently tolerate failures under certain situations. If such application layer information is available to the client-server communication layer (RPC and shared variable), the failure masking algorithms in the communication layer may relax the constraints under which the algorithms may have to operate if the information is not available. The relaxation significantly simplifies the algorithms and the underlying message transport layer and allows formulation of efficient algorithms. This application-driven approach forms the backbone of the failure masking techniques described in the thesis, as outlined below: Orphan handling in RPCs: Using the application-driven approach, the thesis introduces a new technique of adopting the orphans caused by failures during RPCs. The adoption technique is preferable to orphan killing because orphan killing wastes any work already completed and requires rollback which may be expensive and sometimes not meaningful. The thesis incorporates orphan adoption into two schemes of replicating a server: i) Primary-secondary scheme in which one of the replicas of the server acts as the primary and executes RPCs from clients while the other replicas stand by as secondaries. When the primary fails, one of the secondaries becomes the primary, restarts the server execution from the most recent checkpoint and adopts the orphan, ii) Replicated execution scheme in which an RPC on the server is executed by more than one replica of the server. When any of the replicas fails, the orphan generated by the failure is adopted by the surviving replicas. Both schemes employ call re-executions by servers based on the application-level idempotency properties of the calls. Access to shared variables: Contemporary distributed programs deal with a new class of shared variables such as information on name bindings, distributed load and leadership within a service group. Since the consistency constraints on such system variables need not be as strong as those for user data, the access operations on the variables may be made simpler using this application layer information. Along this direction, the thesis introduces an abstraction, which we call application-driven shared variable, to govern access operations on the variables. The algorithms for the access operations on a variable use intra-server group communication and enforce consistency of the variable to the extent required by the application. The thesis describes complete communication models incorporating the application-driven approach to mask failures.
Science, Faculty of
Computer Science, Department of
Graduate

There is an increased demand for higher levels of network availability and reliability. Effective monitoring is necessary to help meet this demand. Loughborough University's High speed Network (HSN) group and many other research groups have preformed significant research related to the monitoring of communication networks and the subsequent processing of the information collected in a meaningful way. This thesis takes latency as an example performance metric. The term 'Data Exception' is then employed to describe delay data that is unusual or unexpected due to some fundamental change in the underlying network performance. Examples of such changes include significant changes in usage patterns or planned alterations. The objective of this work is to process and interpret such communication network performance data at higher levels of understanding, and will focus on three main points:- • Developing a rule based algorithm to automate the detection of Delay Data Exceptions. • Correlating Delay Data Exceptions in different routes in a network to detect the location and the characteristic of the event that caused these Exceptions. • Predicting the effect of an external event on network performance. In addition to the above three points, the research started by improving a previously published technique for detection and classification of Delay Data Exceptions. The nature of the delay patterns in a commercial communication network was the key issue in developing the algorithm for the first section of the work, and a Neural Network was used in the last two research areas. The monitored delay data used in this work was obtained from different sources; the historical performance data of a commercial network, data from simulation and monitoring of test network in previous related research, and also by monitoring two experimental test networks built in the laboratory. The results of the detection algorithm show an improvement in detection performance, and provide more generality and independency of the source of the delay data. The outputs of the approaches used in the event detection and the performance predictions work give good results, and show potentially the ability to locate the underlying events.

There is a growing trend towards integrating physical data into the Internet which is supported by sensor devices, smartphones, GPS and many other sources that capture and communicate real world data. Cyber-Physical Data describes the type of data that represents observations and measurements gathered by sensor devices. These sensor devices are capable of transforming physical information (e.g. light, temperature, coordinates) into digitised data. With tremendous volumes of Cyber-Physical Data that are created, novel methods have to be developed that facilitate processing and provisioning of the data. Automated techniques are required to extract and infer meaningful abstractions for the end-user and/or higherlevel knowledge. Investigation of the related work leads to the conclusion that there has been significant work on communication and processing aspects of Cyber-Physical Data, however, there is a need for integrated solutions that contemplate the workflow from data acquisition to extraction and knowledge representation. We propose a set of novel solutions for Cyber-Physical Data communication and information processing by providing a middleware component that contains management and communication processing capabilities to deliver actionable knowledge to the end-user and services. We have developed a novel data abstraction method for Cyber-Physical Data. The abstraction method is based on a probabilistic graph model and machine-learning teclmiques to extract relevant information and infer knowledge from patterns that are represented by the abstracted data. The proposed approach is able to create human-readable/machine-interpretable abstractions from numerical sensor data with precision rate of 79% and recall of 94%. The automated ontology construction algorithm has a success rate of 84% of representing occurred events in the ontology. Finally, an integrated software system is introduced that uses the middleware and the information processing techniques to provide a complete workflow from data acquisition to knowledge acquisition and representation.

This work describes the design and implementation details of a reliable group communication mechanism. The mechanism guarantees that messages will be received by all the operational members of the group or by none of them (atomicity). In addition, the sequence of messages will be the same at each of the recipients (order). The message ordering property can be used to simplify distributed database systems and distributed processing algorithms. The proposed mechanism continues to operate despite process, host and communication link failures (survivability). Survivability is essential in fault-tolerant applications.
Science, Faculty of
Computer Science, Department of
Graduate

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
Includes bibliographical references (p. 137-142).
by Andrew Carl Singer.
Ph.D.

Database management systems (DBMSs) have been used successfully in traditional business applications that require persistent data storage and an efficient querying mechanism. Typically, it is assumed that the data are static, unless explicitly modified or deleted by a user or application. Database queries are executed when issued and their answers reflect the current state of the data. However, emerging applications, such as sensor networks, real-time Internet traffic analysis, and on-line financial trading, require support for processing of unbounded data streams. The fundamental assumption of a data stream management system (DSMS) is that new data are generated continually, making it infeasible to store a stream in its entirety. At best, a sliding window of recently arrived data may be maintained, meaning that old data must be removed as time goes on. Furthermore, as the contents of the sliding windows evolve over time, it makes sense for users to ask a query once and receive updated answers over time.

This dissertation begins with the observation that the two fundamental requirements of a DSMS are dealing with transient (time-evolving) rather than static data and answering persistent rather than transient queries. One implication of the first requirement is that data maintenance costs have a significant effect on the performance of a DSMS. Additionally, traditional query processing algorithms must be re-engineered for the sliding window model because queries may need to re-process expired data and "undo" previously generated results. The second requirement suggests that a DSMS may execute a large number of persistent queries at the same time, therefore there exist opportunities for resource sharing among similar queries.

The purpose of this dissertation is to develop solutions for efficient query processing over sliding windows by focusing on these two fundamental properties. In terms of the transient nature of streaming data, this dissertation is based upon the following insight. Although the data keep changing over time as the windows slide forward, the changes are not random; on the contrary, the inputs and outputs of a DSMS exhibit patterns in the way the data are inserted and deleted. It will be shown that the knowledge of these patterns leads to an understanding of the semantics of persistent queries, lower window maintenance costs, as well as novel query processing, query optimization, and concurrency control strategies. In the context of the persistent nature of DSMS queries, the insight behind the proposed solution is that various queries may need to be refreshed at different times, therefore synchronizing the refresh schedules of similar queries creates more opportunities for resource sharing.

Thesis (Ph.D.)--Indiana University, Dept. of Computer Science, 2007.
Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 6093. Adviser: Beth Plale. Title from dissertation home page (viewed May 9, 2008).

Il lavoro di tesi consiste in una ricerca empirica sulla comunicazione del tema alimentare. Attorno al cibo si sono recentemente aggregati molti interessi: sociali, economici, industriali, commerciali, politici, mediatici ma anche scientifici. Si tratta di questioni importanti che coinvolgono l’opinione pubblica e attraggono l’attenzione dei media. In una società fortemente mediatizzata diventa rilevante osservare come il discorso pubblico sul cibo e l’alimentazione vada configurandosi nella sfera pubblica. Inoltre, l’insorgenza di numerosi progetti tecnoscientifici che coinvolgono il settore alimentare non possono non suggerire di guardare al cibo, e al suo simbolismo, come un oggetto privilegiato attraverso cui osservare anche i rapporti tra scienza, tecnologia e società. In questo studio si è iniziato a esplorare le caratteristiche della narrazione e della presenza del tema alimentare nell’arena pubblica attraverso un'analisi dei maggiori quotidiani italiani. Una prima analisi longitudinale, nel periodo 1992-2013, ha identificato – attraverso un’innovativa procedura di analisi testuale (topic detection) - la presenza di alcuni temi emergenti. Successivamente, si è proceduto a focalizzare la nostra attenzione sull'ultimo periodo (2010-2016), al fine di concentrarsi sulla maggior parte degli eventi recenti e di verificare se il discorso mediale sul cibo e l’alimentazione abbia assunto nuova rilevanza o nuove forme nell'agenda dei media e nella discussione pubblica. Il lavoro di ricerca si compone di altre due tipi differenti di analisi: da un lato, si discuteranno i risultati emersi dalla realizzazione di tre focus group che ci hanno fornito utili indicazioni sul rapporto tra cibo, media e opinione pubblica; dall’altro abbiamo cercato di individuare una relazione tra copertura mediatica e atteggiamenti espressi dall’opinione pubblica utilizzando un «indice di rischio» e i dati provenienti da alcune survey europee.
Thesis work consists in empirical research on the communication of the food theme, in a techno-scientific framework. Recently, nutrition has been linked to a lot of interests: social, economical, industrial, commercial, political, media but also scientific ones. These are significant issues that concern the public opinion and attract the media attention. In a society that revolves strongly around media, it becomes relevant to observe how the public discourse on themes like food and nutrition is being shaped among the public sphere. In addition, the rising of several techno-scientific projects that concern the field of nutrition cannot help but suggest to look at nutrition, and its symbolism, like a privileged object through which one can also observe the existing ties between science, technology and society. This study started by exploring the characteristics of the narrative of the food theme and its presence in the public arena through an analysis of the main Italian daily newspapers. One former longitudinal analysis, in the time-span 1992-2013, found- through an innovative tool of textual analysis ( topic detection)- the presence of some emerging themes. Next, we shifted our attention to the last period (2010-2016), with the aim to focus on the majority of the recent events and to verify whether the media discourse on food and nutrition gained new relevance or forms in the media agenda and in the public discussion. The research work is composed of two other different kind of analysis: on the one hand, it will discuss the emerging results from three focus groups that provided useful indications on the relationship between food, media and the public opinion; on the other hand, we sought to identify a relation between media coverage and the attitudes of the public opinion by adopting a “risk indicator” and the data from certain European surveys.

Il lavoro di tesi consiste in una ricerca empirica sulla comunicazione del tema alimentare. Attorno al cibo si sono recentemente aggregati molti interessi: sociali, economici, industriali, commerciali, politici, mediatici ma anche scientifici. Si tratta di questioni importanti che coinvolgono l’opinione pubblica e attraggono l’attenzione dei media. In una società fortemente mediatizzata diventa rilevante osservare come il discorso pubblico sul cibo e l’alimentazione vada configurandosi nella sfera pubblica. Inoltre, l’insorgenza di numerosi progetti tecnoscientifici che coinvolgono il settore alimentare non possono non suggerire di guardare al cibo, e al suo simbolismo, come un oggetto privilegiato attraverso cui osservare anche i rapporti tra scienza, tecnologia e società. In questo studio si è iniziato a esplorare le caratteristiche della narrazione e della presenza del tema alimentare nell’arena pubblica attraverso un'analisi dei maggiori quotidiani italiani. Una prima analisi longitudinale, nel periodo 1992-2013, ha identificato – attraverso un’innovativa procedura di analisi testuale (topic detection) - la presenza di alcuni temi emergenti. Successivamente, si è proceduto a focalizzare la nostra attenzione sull'ultimo periodo (2010-2016), al fine di concentrarsi sulla maggior parte degli eventi recenti e di verificare se il discorso mediale sul cibo e l’alimentazione abbia assunto nuova rilevanza o nuove forme nell'agenda dei media e nella discussione pubblica. Il lavoro di ricerca si compone di altre due tipi differenti di analisi: da un lato, si discuteranno i risultati emersi dalla realizzazione di tre focus group che ci hanno fornito utili indicazioni sul rapporto tra cibo, media e opinione pubblica; dall’altro abbiamo cercato di individuare una relazione tra copertura mediatica e atteggiamenti espressi dall’opinione pubblica utilizzando un «indice di rischio» e i dati provenienti da alcune survey europee.
Thesis work consists in empirical research on the communication of the food theme, in a techno-scientific framework. Recently, nutrition has been linked to a lot of interests: social, economical, industrial, commercial, political, media but also scientific ones. These are significant issues that concern the public opinion and attract the media attention. In a society that revolves strongly around media, it becomes relevant to observe how the public discourse on themes like food and nutrition is being shaped among the public sphere. In addition, the rising of several techno-scientific projects that concern the field of nutrition cannot help but suggest to look at nutrition, and its symbolism, like a privileged object through which one can also observe the existing ties between science, technology and society. This study started by exploring the characteristics of the narrative of the food theme and its presence in the public arena through an analysis of the main Italian daily newspapers. One former longitudinal analysis, in the time-span 1992-2013, found- through an innovative tool of textual analysis ( topic detection)- the presence of some emerging themes. Next, we shifted our attention to the last period (2010-2016), with the aim to focus on the majority of the recent events and to verify whether the media discourse on food and nutrition gained new relevance or forms in the media agenda and in the public discussion. The research work is composed of two other different kind of analysis: on the one hand, it will discuss the emerging results from three focus groups that provided useful indications on the relationship between food, media and the public opinion; on the other hand, we sought to identify a relation between media coverage and the attitudes of the public opinion by adopting a “risk indicator” and the data from certain European surveys.

A massive amount of data is being generated at an unprecedented level from a diversity of sources, including social media, internet services, biological studies, physical infrastructure monitoring and many others. The necessity of analyzing such complex data has led to the birth of an emerging framework, graph signal processing. This framework offers an unified and mathematically rigorous paradigm for the analysis of high-dimensional data with complex and irregular structure. It extends fundamental signal processing concepts such as signals, Fourier transform, frequency response and filtering, from signals residing on regular lattices, which have been studied by the classical signal processing theory, to data residing on general graphs, which are called graph signals. In this thesis, we consider five fundamental tasks on graphs from the perspective of graph signal processing: representation, sampling, recovery, detection and localization. Representation, aiming to concisely model shapes of graph signals, is at the heart of the proposed techniques. Sampling followed by recovery, aiming to reconstruct an original graph signal from a few selected samples, is applicable in semi-supervised learning and user profiling in online social networks. Detection followed by localization, aiming to identify and localize targeted patterns in noisy graph signals, is related to many real-world applications, such as localizing virus attacks in cyber-physical systems, localizing stimuli in brain connectivity networks, and mining traffic events in city street networks, to name just a few. We illustrate the power of the proposed tools on two real-world problems: fast resampling of 3D point clouds and mining of urban traffic data.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
Includes bibliographical references (leaf 64).
by Timothy J. Derksen.
M.Eng.

Today, a large amount of spatial data is generated from a variety of sources, such as mobile devices, sensors, and satellites. Traditional spatial data processing techniques no longer satisfy the efficiency and scalability requirements for large-scale spatial data processing. Existing Big Data processing frameworks such as Hadoop and Spark have been extended to support effective large-scale spatial data processing. In addition to processing data in distributed schemes utilizing computer clusters for efficiency and scalability, single node performance can also be improved by making use of multi-core processors. In this thesis, we investigate approaches to parallelize line segment intersection algorithms for spatial computations on multi-core processors, which can be used as node-level algorithms for distributed spatial data processing. We first provide our design of line segment intersection algorithms and introduce parallelization techniques. Then, we describe experimental results using multiple data sets and speed ups are examined with varying numbers of processing cores. Equipped with the efficient underlying algorithm for spatial computation, we investigate how to build a native big spatial data system from the ground up. We provide a system design for distributed large-scale spatial data management and processing using a two-level hash based Quadtree index as well as algorithms for spatial operations.

In the era of big data, many cluster platforms and resource management schemes are created to satisfy the increasing demands on processing a large volume of data. A general setting of big data processing jobs consists of multiple stages, and each stage represents generally defined data operation such as ltering and sorting. To parallelize the job execution in a cluster, each stage includes a number of identical tasks that can be concurrently launched at multiple servers. Practical clusters often involve hundreds or thousands of servers processing a large batch of jobs. Resource management, that manages cluster resource allocation and job execution, is extremely critical for the system performance.

Generally speaking, there are three main challenges in resource management of the new big data processing systems. First, while there are various pending tasks from dierent jobs and stages, it is difficult to determine which ones deserve the priority to obtain the resources for execution, considering the tasks' different characteristics such as resource demand and execution time. Second, there exists dependency among the tasks that can be concurrently running. For any two consecutive stages of a job, the output data of the former stage is the input data of the later one. The resource management has to comply with such dependency. The third challenge is the inconsistent performance of the cluster nodes. In practice, run-time performance of every server is varying. The resource management needs to dynamically adjust the resource allocation according to the performance change of each server.

The resource management in the existing platforms and prior work often rely on fixed user-specic congurations, and assumes consistent performance in each node. The performance, however, is not satisfactory under various workloads. This dissertation aims to explore new approaches to improving the eciency of large-scale big data processing platforms. In particular, the run-time dynamic factors are carefully considered when the system allocates the resources. New algorithms are developed to collect run-time data and predict the characteristics of jobs and the cluster. We further develop resource management schemes that dynamically tune the resource allocation for each stage of every running job in the cluster. New findings and techniques in this dissertation will certainly provide valuable and inspiring insights to other similar problems in the research community.

XML has emerged as a new standard for information representation and exchange on the Internet. To efficiently process XML data, we propose the extended preorder numbering scheme, which determines the ancestor-descendant relationship between nodes in the hierarchy of XML data in constant time, and adapts to the dynamics of XML data by allocating extra space. Based on this numbering scheme, we propose sort-merge based algorithms, εA-Join and εε-Join, to process ancestor-descendant path expressions. The experimental results showed an order of magnitude performance improvement over conventional methods. We further propose the partition-based algorithms, which can be chosen by a query optimizer according to the characteristics of the input data. For complex path expressions with branches, we propose the Containment B⁺-tree (CB-tree) index and the IndexTwig algorithm. The CB-tree, which is an extension of the B⁺-tree, supports both the containment query and the reverse containment query. It is an effective indexing scheme for XML documents with or without a small number of recursions. The proposed IndexTwig algorithm works with any index supporting containment and reverse containment queries, such as the CB-tree. We also introduce a simplified output model, which outputs only the necessary result of a path expression. The output model enables the Fast Existence Test (FET) optimization to skip unnecessary data and avoid generating unwanted results. Also in this dissertation, we introduce techniques to process the predicates in XML path expressions using the EVR-tree. The EVR-tree combines the advantages of indexing on values or elements individually using B+-trees. It utilizes the high value selectivity and/or high structural selectivity, and provides ordered element access by using a priority queue. At the end of the dissertation, we introduce the XISS/R system, which is an implementation of the XML Indexing and Storage System (XISS) on top of a relational database. The XISS/R includes a web-based user interface and a XPath query engine to translate XPath queries into efficient SQL statements.

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 85-86).
While many industries can benefit from machine learning techniques for data analysis, they often do not have the technical expertise nor computational power to do so. Therefore, many organizations would benefit from outsourcing their data analysis. Yet, stringent data privacy policies prevent outsourcing sensitive data and may stop the delegation of data analysis in its tracks. In this thesis, we put forth a two-party system where one party capable of powerful computation can run certain machine learning algorithms from the natural language processing domain on the second party's data, where the first party is limited to learning only specific functions of the second party's data and nothing else. Our system provides simple cryptographic schemes for locating keywords, matching approximate regular expressions, and computing frequency analysis on encrypted data. We present a full implementation of this system in the form of a extendible software library and a command line interface. Finally, we discuss a medical case study where we used our system to run a suite of unmodified machine learning algorithms on encrypted free text patient notes.
by Alex J. Grinman.
M. Eng.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.
Includes bibliographical references.
by Kenneth P. Westlund Jr.
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.