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Towards High Performability in Advanced Metering Infrastructures
No full textThe current movement towards a smart grid serves as a solution to present power grid challenges by introducing numerous monitoring and communication technologies. A dependable, yet timely exchange of data is on the one hand an existential prerequisite to enable Advanced Metering Infrastructure (AMI) services, yet on the other a challenging endeavor, because the increasing complexity of the grid fostered by the combination of Information and Communications Technology (ICT) and utility networks inherently leads to dependability challenges.
To be able to counter this dependability degradation, current approaches based on high-reliability hardware or physical redundancy are no longer feasible, as they lead to increased hardware costs or maintenance, if not both. The flexibility of these approaches regarding vendor and regulatory interoperability is also limited. However, a suitable solution to the AMI dependability challenges is also required to maintain certain regulatory-set performance and Quality of Service (QoS) levels.
While a part of the challenge is the introduction of ICT into the power grid, it also serves as part of the solution. In this thesis a Network Functions Virtualization (NFV) based approach is proposed, which employs virtualized ICT components serving as a replacement for physical devices. By using virtualization techniques, it is possible to enhance the performability in contrast to hardware based solutions through the usage of virtual replacements of processes that would otherwise require dedicated hardware. This approach offers higher flexibility compared to hardware redundancy, as a broad variety of virtual components can be spawned, adapted and replaced in a short time. Also, as no additional hardware is necessary, the incurred costs decrease significantly. In addition to that, most of the virtualized components are deployed on Commercial-Off-The-Shelf (COTS) hardware solutions, further increasing the monetary benefit.
The approach is developed by first reviewing currently suggested solutions for AMIs and related services. Using this information, virtualization technologies are investigated for their performance influences, before a virtualized service infrastructure is devised, which replaces selected components by virtualized counterparts. Next, a novel model, which allows the separation of services and hosting substrates is developed, allowing the introduction of virtualization technologies to abstract from the underlying architecture. Third, the performability as well as monetary savings are investigated by evaluating the developed approach in several scenarios using analytical and simulative model analysis as well as proof-of-concept approaches. Last, the practical applicability and possible regulatory challenges of the approach are identified and discussed.
Results confirm that—under certain assumptions—the developed virtualized AMI is superior to the currently suggested architecture. The availability of services can be severely increased and network delays can be minimized through centralized hosting. The availability can be increased from 96.82% to 98.66% in the given scenarios, while decreasing the costs by over 60% in comparison to the currently suggested AMI architecture. Lastly, the performability analysis of a virtualized service prototype employing performance analysis and a Musa-Okumoto approach reveals that the AMI requirements are fulfilled
Credit card fraud detection using machine learning with integration of contextual knowledge
No full textWe have proposed a strategy for the creation of attributes based on hidden Markov models (HMM) characterizing the transaction from different points of view. This strategy makes it possible to integrate a broad spectrum of sequential information into the attributes of transactions. In fact, we model the authentic and fraudulent behavior of merchants and card holders according to two univariate characteristics: the date and the amount of transactions. In addition, attributes based on HMMs are created in a supervised manner, thereby reducing the need for expert knowledge for the creation of the fraud detection system. Ultimately, our HMM-based multi-perspective approach allows automated data pre-processing to model time correlations to complement and eventually replace transaction aggregation strategies to improve detection efficiency. Experiments carried out on a large set of credit card transaction data from the real world (46 million transactions carried out by Belgian card holders between March and May 2015) have shown that the strategy proposed for data preprocessing based on HMM can detect more fraudulent transactions when combined with the strategy of preprocessing reference data based on expert knowledge for the detection of credit card fraud
Internationale Standards für die Vollstreckung von Zivilurteilen: Aktuelle Situation und mögliche Lösungen für Vietnam
No full textDas Ziel der vorliegenden Dissertation ist es, Erkenntnisse für eine mögliche Verbesserung des vietnamesischen Zwangsvollstreckungsrechts zu gewinnen, um in Vietnam ein effektives und effizientes Vollstreckungsverfahren zu erreichen, das im Einklang mit den internationalen Standards steht. Das erste Kapitel untersucht die neuen internationalen Standards im Bereich der Vollstreckung von Zivilurteilen und behandelt sie im Vergleich mit wichtigen Grundsätzen der Vollstreckung von Gerichtsurteilen in Vietnam. Der zweite Kapitel widmet sich dem Aufbau und der Organisation der Vollstreckungsbehörden und dabei insbesondere den folgenden Themen: Den Vorteilen des Aufbaus eines Berufsverbands der Gerichtsvollzieher, welcher alle Mitglieder des Berufsstandes umfasst. Das dritte Kapitel zeigt unter anderem, dass wirksame Mechanismen zur Vollstreckung von Entschreidungen den Grundsatz der Verhältnismäßigkeit einhalten müssen. Das vierte Kapitel stellt die internationalen Normen über den einstweiligen Rechtsschutz dar, der ein unverzichtbares Mittel ist, um die Durchsetzung von Zivilurteilen zu gewährleisten.
Basierend auf den Ergebnissen aus den vier Kapiteln ergeben sich eine Reihe von wertvollen Erkenntnissen für die Verbesserung des vietnamesischen Rechtssystems und die Verbesserung der Effizienz der Vollstreckung zivilgerichtlicher Urteile
Zu jeder Aufgabe die richtige Strategie? Zum Stellenwert literarischer Strategien für Aufgaben im kompetenzorientierten Literaturunterricht
No full textIm folgenden Text sollen diese zwei grundlegenden Herausforderungen für den Literaturunterricht fokussiert werden: Einerseits geht es um eine höhere Zielbewusstheit, also darum, dass die Lernenden wissen, welche Ziele sie im Literaturunterricht erreichen sollen und welche Kriterien für das Erreichen dieser Ziele erfüllt werden müssen. Auf der anderen Seite werden Strategien beschrieben, die für die Zielerreichung angewendet werden können und mit denen ein Fortschritt im Lernprozess erreicht werden kann. Theoretische Grundlage für diese Strategien bildet das semiotische Modell literarischer Kompetenz von Schilcher/Pissarek (Hrsg.)
Methods for monitoring the human circadian rhythm in free-living
Get PDFOur internal clock, the circadian clock, determines at which time we have our best cognitive abilities, are physically strongest, and when we are tired. Circadian clock phase is influenced primarily through exposure to light. A direct pathway from the eyes to the suprachiasmatic nucleus, where the circadian clock resides, is used to synchronise the circadian clock to external light-dark cycles.
In modern society, with the ability to work anywhere at anytime and a full social agenda, many struggle to keep internal and external clocks synchronised. Living against our circadian clock makes us less efficient and poses serious health impact, especially when exercised over a long period of time, e.g. in shift workers. Assessing circadian clock phase is a cumbersome and uncomfortable task. A common method, dim light melatonin onset testing, requires a series of eight saliva samples taken in hourly intervals while the subject stays in dim light condition from 5 hours before until 2 hours past their habitual bedtime.
At the same time, sensor-rich smartphones have become widely available and wearable computing is on the rise. The hypothesis of this thesis is that smartphones and wearables can be used to record sensor data to monitor human circadian rhythms in free-living. To test this hypothesis, we conducted research on specialised wearable hardware and smartphones to record relevant data, and developed algorithms to monitor circadian clock phase in free-living. We first introduce our smart eyeglasses concept, which can be personalised to the wearers head and 3D-printed. Furthermore, hardware was integrated into the eyewear to recognise typical activities of daily living (ADLs). A light sensor integrated into the eyeglasses bridge was used to detect screen use. In addition to wearables, we also investigate if sleep-wake patterns can be revealed from smartphone context information. We introduce novel methods to detect sleep opportunity, which incorporate expert knowledge to filter and fuse classifier outputs. Furthermore, we estimate light exposure from smartphone sensor and weather in- formation. We applied the Kronauer model to compare the phase shift resulting from head light measurements, wrist measurements, and smartphone estimations.
We found it was possible to monitor circadian phase shift from light estimation based on smartphone sensor and weather information with a weekly error of 32±17min, which outperformed wrist measurements in 11 out of 12 participants. Sleep could be detected from smartphone use with an onset error of 40±48 min and wake error of 42±57 min. Screen use could be detected smart eyeglasses with 0.9 ROC AUC for ambient light intensities below 200lux. Nine clusters of ADLs were distinguished using Gaussian mixture models with an average accuracy of 77%. In conclusion, a combination of the proposed smartphones and smart eyeglasses applications could support users in synchronising their circadian clock to the external clocks, thus living a healthier lifestyle
Modelling of a Privacy Language and Efficient Policy-based De-identification
Get PDFThe processing of personal information is omnipresent in our data-driven society enabling personalized services, which are regulated by privacy policies. Although privacy policies are strictly defined by the General Data Protection Regulation (GDPR), no systematic mechanism is in place to enforce them. Especially if data is merged from several sources into a data-set with different privacy policies associated, the management and compliance to all privacy requirements is challenging during the processing of the data-set. Privacy policies can vary hereby due to different policies for each source or personalization of privacy policies by individual users. Thus, the risk for negligent or malicious processing of personal data due to defiance of privacy policies exists.
To tackle this challenge, a privacy-preserving framework is proposed. Within this framework privacy policies are expressed in the proposed Layered Privacy Language (LPL) which allows to specify legal privacy policies and privacy-preserving de-identification methods. The policies are enforced by a Policy-based De-identification (PD) process. The PD process enables efficient compliance to various privacy policies simultaneously while applying pseudonymization, personal privacy anonymization and privacy models for de-identification of the data-set. Thus, the privacy requirements of each individual privacy policy are enforced filling the gap between legal privacy policies and their technical enforcement
Universitätsbibliothek Passau: Jahresbericht 2019
No full textJahresbericht der Universitätsbibliothek Passau für das Jahr 2019
Subjektives Wohlbefinden von Studierenden - Einflussfaktoren auf das subjektive Wohlbefinden und Zusammenhänge mit der Studienabbruchsintention
Get PDFDie Arbeit besteht aus drei empirischen Studien, die als übergeordnete Forschungsfragen untersuchen sollten, welche signifikanten Prädiktoren das subjektive Wohlbefinden bei Studierenden beeinflussen können und zum anderen klären sollte, ob das subjektive Wohlbefinden in einem Zusammenhang mit der Studienabbruchsintention steht. Jede Studie baute auf den Hauptprädiktoren Persönlichkeit, Selbstkonzept und soziale Integration auf und hatte zugleich noch einen spezifischen Aspekt, der sich von Studie zu Studie änderte. In der ersten Studie wurde als zusätzliche Variable der Identitätsstatus betrachtet. An dieser Erhebung nahmen Studierende ab dem zweiten Semester teil und sie wurde im Querschnitt durchgeführt. Die zentralen Ergebnisse waren hinsichtlich des subjektiven Wohlbefindens die Bedeutung von Neurotizismus, Extraversion, dem Selbstkonzept der allgemeinen Problemlösung und die deutlich unterschiedlichen Ergebnisse zwischen Frauen und Männern. So hatte bei den Studentinnen vor allem Neurotizismus einen Einfluss und bei Männern hingegen die Extraversion. Hinsichtlich der Studienabbruchsintention zeigte sich ein vollständiger Mediatoreffekt zwischen der sozialen Eingebundenheit und der Studienabbruchsintention mit dem subjektiven Wohlbefinden als Mediator. Im Pfadmodell zeigte sich allerdings kein signifikanter Zusammenhang zwischen dem subjektiven Wohlbefinden und der Studienabbruchsintention. In der zweiten Studie lag der Fokus auf Studierenden im ersten Semester in einer Längsschnittuntersuchung und spezifizierte sich auf Aspekte der Motivation, die allerdings keine Zusammenhänge zeigten. Auch hier gab es einen vollständigen Mediatoreffekt des subjektiven Wohlbefindens hinsichtlich des Regressionspfades zwischen sozialer Integration und Studienabbruchsintention. Die dritte Studie legte den Schwerpunkt auf die Bedeutung der Grundbedürfnisse nach Deci & Ryan (2000) und die Emotionsregulationsstrategien Neubewertung und Unterdrückung. Die Teilnehmenden waren Studierende ab dem zweiten Semester, die im Längsschnitt befragt wurden. Beim ersten Messzeitpunkt während des Semesters waren das Autonomieerleben, Neurotizismus und das Selbstkonzept der allgemeinen Problemlösung signifikante Prädiktoren des subjektiven Wohlbefindens, beim zweiten Messzeitpunkt war der einzige, signifikante Prädiktor im Pfadmodell die Persönlichkeitsdimension Verträglichkeit. Zwischen dem subjektiven Wohlbefinden und der Studienabbruchsintention zeigte sich ein signifikanter Zusammenhang
The System Of The Naxi Language
No full textDie Naxi verwenden eine Sprache, in der Segmente und Suprasegmente in komplexer Weise in Wörtern zum Ausdruck kommen. Im Satz wird die Grammatik grundsätzlich in analytischer Weise durch Partikeln strukturiert. Die Naxi verwenden einzigartige Zeichen, die entweder stilisierte Umrisse von der Natur (die Domba-Zeichen) oder hoch abstrakt (die Geba-Zeichen) sind, um Gegenstände bzw. Ausprachen zu symbolisieren
Multiparty Protocols for Tree Classifiers
No full textCryptography is the scientific study of techniques for securing information and communication against adversaries. It is about designing and analyzing encryption schemes and protocols that protect data from unauthorized reading. However, in our modern information-driven society with highly complex and interconnected information systems, encryption alone is no longer enough as it makes the data unintelligible, preventing any meaningful computation without decryption. On the one hand, data owners want to maintain control over their sensitive data. On the other hand, there is a high business incentive for collaborating with an untrusted external party.
Modern cryptography encompasses different techniques, such as secure multiparty computation, homomorphic encryption or order-preserving encryption, that enable cloud users to encrypt their data before outsourcing it to the cloud while still being able to process and search on the outsourced and encrypted data without decrypting it. In this thesis, we rely on these cryptographic techniques for computing on encrypted data to propose efficient multiparty protocols for order-preserving encryption, decision tree evaluation and kth-ranked element computation.
We start with Order-preserving encryption (OPE) which allows encrypting data, while still enabling efficient range queries on the encrypted data. However, OPE is symmetric limiting, the use case to one client and one server. Imagine a scenario where a Data Owner (DO) outsources encrypted data to the Cloud Service Provider (CSP) and a Data Analyst (DA) wants to execute private range queries on this data. Then either the DO must reveal its encryption key or the DA must reveal the private queries. We overcome this limitation by allowing the equivalent of a public-key OPE.
Decision trees are common and very popular classifiers because they are explainable. The problem of evaluating a private decision tree on private data consists of a server holding a private decision tree and a client holding a private attribute vector. The goal is to classify the client’s input using the server’s model such that the client learns only the result of the classification, and the server learns nothing. In a first approach, we represent the tree as an array and execute only d interactive comparisons (instead of 2 d as in existing solutions), where d denotes the depth of the tree. In a second approach, we delegate the complete tree evaluation to the server using somewhat or fully homomorphic encryption where the ciphertexts are encrypted under the client’s public key.
A generalization of a decision tree is a random forest that consists of many decision trees. A classification with a random forest evaluates each decision tree in the forest and outputs the classification label which occurs most often. Hence, the classification labels are ranked by their number of occurrences and the final result is the best ranked one. The best ranked element is a special case of the kth-ranked element. In this thesis, we consider the secure computation of the kth-ranked element in a distributed setting with applications in benchmarking and auctions. We propose different approaches for privately computing the kth-ranked element in a star network, using either garbled circuits or threshold homomorphic encryption