796 research outputs found
Hybrid Fault-Tolerant Consensus in Asynchronous and Wireless Embedded Systems
No full textByzantine fault-tolerant (BFT) consensus in an asynchronous system can only tolerate up to floor[(n-1)/3] faulty processes in a group of n processes. This is quite a strict limit in certain application scenarios, for example a group consisting of only 3 processes. In order to break through this limit, we can leverage a hybrid fault model, in which a subset of the system is enhanced and cannot be arbitrarily faulty except for crashing. Based on this model, we propose a randomized binary consensus algorithm that executes in complete asynchrony, rather than in partial synchrony required by deterministic algorithms. It can tolerate up to floor[(n-1)/2] Byzantine faulty processes as long as the trusted subsystem in each process is not compromised, and terminates with a probability of one. The algorithm is resilient against a strong adversary, i. e. the adversary is able to inspect the state of the whole system, manipulate the delay of every message and process, and then adjust its faulty behaviour during execution.
From a practical point of view, the algorithm is lightweight and has little dependency on lower level protocols or communication primitives. We evaluate the algorithm and the results show that it performs promisingly in a testbed consisting of up to 10 embedded devices connected via an ad hoc wireless network
Blockchain-Based Architectures for Managed Distributed Data Access
No full textNowadays, massive amounts of data are constantly generated.
The question of data governance, however, is complex: while consumers often believe they control their generated data, it is the service provider who owns and profits from it.
The main challenges are equal data access between untrusted companies and partial data access between consumer and service provider so that the consumer retains control over her data.
In this thesis, we investigate the requirements of these challenges and present different approaches for managed distributed data access.
These build on blockchain-based distributed ledger technologies, which offer tamper-evident, transparent, replicated, and reliable data storage in a network of mutually distrustful participants.
We first introduce a distributed juridical recording unit for railway systems that logs safety-relevant information.
It allows all companies involved in the train's life cycle to participate in the recording and thus share equal data access while fulfilling the strict regulatory requirements of such devices.
Our system opportunistically utilises on-train hardware and offers high reliability via replication and tamper-resistance due to the blockchain properties.
A Byzantine agreement protocol suitable for diverse communication systems ensures timely and fault-tolerant data ordering.
The recording is securely and continuously exported to the companies.
Next, we present a crowdsensing approach for social networks to limit the spread of fake news.
Our system enables users to attach a location-based trust score to their posts.
For this, users' mobility traces are collected and evaluated securely and privacy-preservingly, and other nearby users can interactively provide assessments.
Data is secured via hybrid encryption by the user, stored on the tamper-resistant blockchain, and evaluated by a smart contract running inside a trusted execution environment.
This ensures that mobility traces are confidential and, as users maintain access control, enables partial data access.
Furthermore, we maximise the applicability of blockchain systems in new domains by allowing operators to flexibly optimise the platform regarding the ordering mechanism for block creation.
For this, we present a blockchain-specific consensus proxy running inside a trusted execution environment on the ordering nodes.
It provides a transparent abstraction layer between blockchain network and generic ordering protocols, thereby allowing easy integration of Byzantine agreement protocols.Heutzutage werden konstant riesige Datenmengen erzeugt.
Die Frage zu Data Governance ist jedoch komplex: während Verbraucher im Glauben sind, dass sie ihre generierten Daten kontrollieren, ist es tatsächlich der Dienstleister, der diese besitzt und von ihnen profitiert.
Die größten Herausforderungen sind der gleichberechtigte Datenzugriff zwischen nicht vertrauenswürdigen Unternehmen sowie der zwischen Verbraucher und Dienstleister partiell geteilte Datenzugriff, durch den der Verbraucher die Kontrolle über seine Daten behält.
Diese Arbeit untersucht die davon gestellten Anforderungen und präsentiert verschiedene Ansätze für verwalteten, verteilten Datenzugriff.
Diese bauen auf Blockchain-basierten Distributed Ledger Technologien auf, die Daten in einem Netzwerk aus sich gegenseitig misstrauenden Teilnehmern so speichern, dass sie transparent, repliziert und zuverlässig sind und nachträgliche Manipulationen erkannt werden können.
Zuerst wird ein verteilter Fahrtenschreiber zur Aufzeichnung sicherheitsrelevanter Informationen in Eisenbahnsystemen vorgestellt.
Alle am Lebenszyklus eines Zuges beteiligten Unternehmen können an der Aufzeichnung mitwirken und teilen sich somit den gleichberechtigten Datenzugriff, während das System zugleich die strengen regulatorischen Anforderungen dieser Geräteklasse erfüllt.
Das System verwendet opportunistisch die vorhandene Zughardware und bietet hohe Zuverlässigkeit durch Replikation sowie Manipulationssicherheit durch die Blockchain.
Ein für verschiedene Kommunikationssysteme konzipiertes Byzantinisches Einigungsprotokoll gewährleistet eine fristgerechte und fehlertolerante Aufzeichnung zum sicheren und kontinuierlichen Export an die Unternehmen.
Anschließend wird ein Ansatz für Crowdsensing zur Begrenzung der Verbreitung von Fake News in Sozialen Netzwerken präsentiert.
Das System ermöglicht es Nutzern, einen auf ihrer Position basierenden Trust Score an ihre Posts anzuhängen.
Dafür werden die Bewegungsprofile der Nutzer auf eine sichere und ihre Privatsphäre wahrende Art gesammelt und ausgewertet.
Andere, sich in der Nähe befindliche Nutzer können interaktive Bewertungen beisteuern.
Die Daten werden vom Nutzer durch hybride Verschlüsselung gesichert, auf der manipulationssicheren Blockchain gespeichert und in einem Smart Contract in einer vertrauenswürdigen Ausführungsumgebung ausgewertet.
Dies ermöglicht partiell geteilten Datenzugriff, da der Nutzer hier die Zugriffskontrolle behält.
Des Weiteren wird ein Ansatz zur Maximierung der Anwendbarkeit von Blockchain-basierten Systemen in neuen Domänen präsentiert, der es Betreibern ermöglicht, diese Systeme flexibel hinsichtlich des Einigungsmechanismus für die Blockerstellung zu optimieren.
Hierfür wird ein Blockchain-spezifischer Einigungsproxy vorgestellt, der in einer vertrauenswürdigen Ausführungsumgebung auf den Einigungsknoten läuft.
Er stellt eine transparente Abstraktionsschicht zwischen dem Blockchain-Netzwerk und dem generischen Einigungsprotokoll dar und erlaubt so die einfache Integration von Byzantinischen Einigungsprotokollen
Snow cover fraction on land fromt MODIS at the three GEM sites
No full textSnow cover fraction on ground from MODIS.
Gaps due to cloud cover are filled using the last available observation. A description paper is in preparation.Please contact the author directly with any questions
Themis: BFT Framework written in Rust + PBFT implementation
No full textByzantine fault tolerant (BFT) protocols have previously been developed mainly in C or Java. C offers high performance but is more error-prone, leading to more potential Byzantine faults, whereas Java offers memory safety at the cost of performance. The Rust programming language combines the performance advantages of C with safe memory management, and newer releases now enable the implementation of complex, non-blocking asynchronous frameworks, as is needed for efficient BFT frameworks. This archive contains Themis a BFT framework implementation in Rust
Environmental Labeling, Protected Geographical Indications and the Interests of Developing Countries
No full textAmong developing countries, one can identify both proponents and opponents of extending the use of geographical indications (GIs) beyond wines and spirits. Such an extension is currently being discussed under the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) of the World Trade Organization. While labeling is mostly based on private initiatives, GIs are considered to be long-term public rights. Proponents therefore regard GIs as the stronger tools for protecting their national property rights and offering them new opportunities to develop their export markets. Opponents, however, consider GIs to be new barriers to trade that impede their export opportunities. This article clarifies these positions and pulls together some evidence on costs and benefits related to GIs versus labels.developing countries, geographical indications, labeling, WTO, Food Consumption/Nutrition/Food Safety, International Relations/Trade,
Promotion of phonemic phonological perception for 5 – 6 years old children with phonological disorders by using natural materials
No full textDiplomdarba nosaukums: “Fonemātiskās uztveres sekmēšana 5 – 6 gadus veciem bērniem ar fonētiski fonemātiskiem traucējumiem, izmantojot dabas materiālus” Darba autore: Signe Jonase Darba zinātniskā vadītāja: Mg. paed. Egija Laganovska Darba saturs: 61 lapas, 7 attēli, 7 tabulas, 4 pielikumi. Pētījuma mērķis: Teorētiski izpētīt un praktiski pārbaudīt dabas materiālu izmantošanas efektivitāti 5 – 6 gadus veciem bērniem ar fonētiski fonemātiskiem traucējumiem. Pētījuma teorētiskajā daļā tiek analizēta dažādu autoru zinātniskā literatūra. Darba autore apraksta bērnu attīstību kopveselumā (fizisko, emocionālo, kognitīvo un sociālo), fonemātiskā uztvere, tās traucējumi un attīstīšanas paņēmieni. Pētījuma empīriskajā daļā autore apraksta pētnieciski praktisko darbību (novērošanu, runas pārbaudi, anketēšanu), balstoties uz teorētiskajā daļā gūtajām atziņām, kā arī, veic iegūto rezultātu analīzi. Pētījuma rezultātā iegūtie dati tiek apkopoti tabulās un attēlos. Darba noslēgumā tiek izdarīti secinājumi un sniegti ieteikumi vecākiem un pedagogiem. Atslēgas vārdi: logopēdija, runa, valoda, attīstība, skaņu izrunas traucējumi, fonemātiskās uztvere, fonemātiskās uztveres traucējumi, dabas materiāli.Title of graduation work: “Promotion of phonemic phonological perception for 5 – 6 years old children with phonological disorders by using natural materials” Author: Signe Jonase Supervisor: Mg. paed. Egija Laganovska Structure: 61 pages, 7 pictures, 7 tables, 4 attachments Reserch goal: In theory, study and practice the effectiveness of the use of natural materials for children 5 to 6 years old with phonetic phonetic phonemic disorders. The theoretical part of the study analyses the scientific literature of the authors. The author of the work describes the development of children in general (physical, emotional, cognitive and social), phonographic perception, its disorders and development techniques. In the empirical part of the study, the author describes the practice of research (observation, speech testing, anketting), based on the lessons learned from the theoretical part, as well as an analysis of the results obtained. The resulting data from the study is collected in tables and images. The work concludes by drawing conclusions and making recommendations to parents and teachers. Key words: speech therapy, speech, language, development, phonetic disorders, phonetic perception, phonetic perception disorders, natural material
Possibilities of electricity production development in Latvia
No full textLatvija ir viena no ES līderēm atjaunojamo energoresursu izmantošanā elektroenerģijas ražošanā, tomēr vēja potenciāls Latvijā nav apgūts.
Maģistra darba Elektroenerģijas ražošanas attīstības iespējas Latvijā autore Signe Allena izvirzījusi mērķi izvērtēt vēja enerģijas izmantošanas potenciālu Rīgas Tehniskajā universitātē, uzstādot mazās vēja turbīnas. Galvenie uzdevumi mērķa īstenošanai ir analizēt zinātniskās publikācijas un praktisko pieredzi, apkopot vēja mērījumus, noteikt vēja turbīnu iespējamo saražotās elektroenerģijas apjomu, izstrādāt elektroenerģijas cenu scenārijus, izvērtēt atmaksāšanās periodus turbīnu uzstādīšanai un noteikt ekonomiski izdevīgāko vēja turbīnu modeli.
Maģistra darba rezultātā ir izvērtēts vēja enerģijas potenciāls un novērtēts ekonomiskais izdevīgums vēja turbīnu uzstādīšanai Rīgas Tehniskajā universitātē.
Atslēgvārdi: elektroenerģijas ražošana, vēja enerģija, statistiskā analīzeLatvia are one of the leading countries in renewable energy usage in electricity generation at EU level, however wind potential is still unfulfilled.
Author Signe Allena of master thesis Possibilities of electricity production development in Latvia aims to assess the wind energy potentional installing small wind turbines at Riga Technical University. The main tasks are to analyze scientific publications and practical experience, gather wind measurements, determine the potentional electricity amount generated by wind turbines, develop electricity price scenarios, evaluate financial return periods of turbine installation and identify the most economically attractive wind turbine model.
As a result of the master thesis the potential of wind energy has been identified and economic advantage of turbine installation at Riga Technical University has been assessed.
Keywords: power generation, wind power, statistical analysi
Work environment risks in metalworking industry and prevention measures
No full text“Metālapstrādē nodarbināto darba vides riski un to novēršanas pasākumi”. Darba autore Signe Vējkrīgere. Darba zinātniskā vadītāja: asoc. profesore, Dr. med. Ženija Roja. Maģistra darbs sastāv no 4 nodaļām, secinājumiem un praktiskajām rekomendācijām. Pirmajā nodaļā literatūras avotos publicētā informācija par metālapstrādes nozarē sastopamajiem darba vides riska faktoriem, to cēloņiem un ietekmi uz nodarbināto veselību. Otrajā daļā aprakstītas darbā izmantotās risku novērtēšanas metodes, bet trešajā daļā – apkopoti un analizēti pētījuma rezultāti. Ceturtā nodaļa ir vadlīnijas veselīgas un drošas darba vides nodrošināšanai metālapstrādē nodarbinātajiem, iekļaujot risku novēršanas un samazināšanas pasākumus nozarē. Darba apjoms ir 76 lpp., satur 21 attēlu, 12 tabulas, 12 pielikumus, izmantots 51 literatūras avots. Darbs uzrakstīts latviešu valodā. Atslēgvārdi: Darba vide, analīze, vadlīnijas, metālapstrāde“Work environment risks in metalworking industry and prevention measures”. Author: Signe Vējkrīgere. Scientific advisor: asoc. prof., Dr. med. Ženija Roja. Master’s thesis consists of four sections, conclusions. The first section analyzes published information from literature sources on occupational risk factors, their causes and impact on employees health in metalworking industry. The second section describes risk assessment methods, that are used in this thesis, but the third section – summary and analysis of results. Fourth section is guidelines how to provide safe and healthy work environment for metalworking industry’s employees, which includes occupational risk reduction and prevention measures. Master’s thesis contain 76 pages, including 21 figures, 12 tables, 51 literature references, 12 appendices. Thesis is written in Latvian. Keywords: Work environment, analysis, guidelines, metalworking
Awareness raising of ecological lifestyle for children of older preschool age
No full textTemats – Ekoloģiska dzīvesveida izpratnes pilnveide vecākajā pirmsskolas vecumā Darba autore – Signe Sokova Darba vadītāja – Dr. Psych. Tija Zīriņa Pētījuma mērķis – pētīt ekoloģiska dzīvesveida izpratnes pilnveidi vecākā pirmsskolas vecuma bērniem mācību jomu centros. Darbs sastāv no teorētiskās un empīriskās daļas. Teorētiskajā daļā, analizējot V. Zelmeņa, G. Svences un citu latviešu un ārzemju psihologu un pedagogu darbus, izpētīts izpratnes un ekoloģijas jēdziens. Darbā raksturots vecākā pirmsskolas vecuma bērna attīstības likumsakarības pētāmās problēmas kontekstā. Empīriskajā daļā tiek raksturoti bērni pēc viņu uzvedības īpatnībām, veikta analīze. Pētītas metodes, ar kādām sekmīgāk veidot izpratni par ekoloģiska dzīvesveida pamatprincipiem. Atslēgas vārdi: ekoloģiskais dzīvesveids, izpratne, vecākā pirmsskolas vecuma bērni, vecumposmu likumsakarības.Research topic– Awareness raising of ecological lifestyle for children of older preschool age Author – Signe Sokova Supervisor – Dr. psych. Tija Zīriņa Research objective- study awareness raising improvement of ecological lifestyle for children of older preschool age in learning centers. The research consists of a theoretical and an empirical part. In the theoretical part, analyzing the works of V. Zemlenis, G. Svence and other Latvian and foreign psychologists and teachers, the concept of understanding and ecology is studied. The paper describes peculiarities of the oldest preschool age in the context of the research problem. In the empirical part, children are described according to their behavioral characteristics, analysis is performed. Methods for better understanding of the basic principles of ecological lifestyle have been studied. Key words: ecological lifestyle, awareness, children of the older pre-school age, peculiarities of the age period
[Review of] Signe Hammer. Daugh ters and Mothers: Mothers and Daughters
No full textPoet, actress, and author ( Women: Body and Culture), Signe Hammer here attempts an exploration of the complex bonds and strains between women, their daughters, and their mothers. While it is written for a popular audience, the book\u27s credibility is strengthened by the inclusion of scholarly chapter notes following the final chapter
- …
