Distributed trustworthy sensor data management architecture

Abstract. Growth in Internet of Things (IoT) market has led to larger data volumes generated by massive amount of smart sensors and devices. This data flow must be managed and stored by some data management service. Storing data to the cloud results high latency and need to transfer large amount of data over the Internet. Edge computing operates physically closer to the user than cloud, offering lower latency and reducing data transmission over the network. Going one step forward and storing data locally to the IoT device results smaller latency than cloud and edge computing. Utilizing isolation technique like virtualization enables easy to deploy environment to setup the needed software functionalities. Container technology works well on lightweight hardware as it offers good performance and small overhead. Containers are used to manage server-side services and to give clean environment for each test run. In this thesis two data management platforms, Apache Kafka and MySQL-based MariaDB are tested on a IoT platform. Key performance parameters considered for these platforms are latency and data throughput while also collecting system resource usage data. Variable amount of users and payload sizes are tested and results are presented in graphs. Kafka performed similarly to the SQL-based solution with small differences.Hajautettu luotettava anturidatan hallintajärjestelmä. Tiivistelmä. IoT-markkinoiden kasvu on johtanut suurempien datamäärien luontiin IoT-laitteiden toimesta. Tuo datavirta täytyy hallita and varastoida datan käsittelypalvelun toimesta. Datan tallennus pilvipalveluihin tuottaa suuren latenssin ja tarpeen suurien datamäärien siirrolle Internetin yli. Fyysisesti lähempänä loppukäyttäjää oleva reunapalvelu tarjoaa pienemmän latenssin ja vähentää siirrettävän datan määrää verkon yli. Kun palvelu tuodaan vielä askel lähemmäksi, päästään paikalliseen palveluun, mikä saavuttaa vielä pienemmän latenssin kuin pilvi- ja reunapalvelut. Virtualisointitekniikka mahdollistaa helposti jaettavan ympäristön käyttöönottoa, mikä mahdollistaa tarvittavien ohjelmiston toimintojen asennuksen. Virtualisointitekniikoista kontit nousivat muiden edelle, koska IoT-laitteet omaavat suhteellisesti vähän muistia ja laskentatehoa. Kontteja käytetään palvelinpuolen palveluiden hallintaan sekä tarjoamaan puhtaan vakioidun ympäristön jokaiselle testikierrokselle. Tämä diplomityö käsittelee kahden tiedonhallinta-alustan: Apache Kafka ja MySQL pohjaisen MariaDB-tietokannan suorituskykyeroja IoT-alustan päällä. Kerätyt suorituskykymittaukset ovat latenssi ja tiedonsiirtonopeus mitaten samalla järjestelmän resurssien käyttöasteita. Vaihtelevia määriä käyttäjiä ja hyötykuormia testataan ja tulokset esitetään graafeissa. Kafka suoriutui yhtä hyvin kuin SQL ohjelmisto näissä testeissä, mutta pieniä eroja näiden välillä havaittiin

FM-, ASK- ja FSK-modulaatioiden toteuttaminen Matlab-Simulink ympäristössä USRP ohjelmistoradiolaitteella

Tässä työssä tutkitaan ja toteutetaan Labview-ympäristössä toteutettujen USRP-2900 mallien toteuttamista Matlab-Simulink-ympäristössä. Työssä toteutetut mallit kykenevät toimimaan saman tapaisesti, kuin lähtökohtana olleet Labview-mallit. Näitä malleja tehdessä esiin tuli ohjelmallisia haasteita, jotka on tuotu esille mahdollisten ratkaisujen kanssa. Työssä kerättyjä havaintoja ja kokemuksia voidaan hyödyntää myös muiden analogisten ja digitalisten tiedonsiirtojärjestelmien Matlab-Simulink-mallien luomisessa USRP-ohjelmistoradiosovelluksiksissa.This work concentrates on research and implementation of USRP-2900 templates which are made in Labview environment and have to be converted into Simulink environment. Templates made in this work will produce same outcome as reference templates from Labview environment. Problems that occurred in the process are documented and possible solutions are explained. Observations gathered from this work can also be used making new models with other analog and digital data transmission systems using USRP software radio in Matlab-Simulink environment

Comparison of impact-abrasive wear characteristics and performance of direct quenched (DQ) and direct quenched and partitioned (DQ&P) steels

Abstract The recently developed method of direct quenching and partitioning (DQ&P) was utilized to produce ultra-high strength martensitic steels with retained austenite. The DQ&P steels have high surface hardness while retaining good impact toughness and elongation values. The toughness and elongation properties are attributed to the retained austenite which is stabilized in the DQ&P process. The aim was to study if DQ&P processing could be utilized for improved abrasive wear resistance. Two medium-carbon (0.3%) chemical compositions were selected with varying amounts of silicon, aluminum and chromium. The processing route for DQ&P involved interrupted water quenching with two different quench stop temperatures (TQ) (175 and 225 °C). Direct quenched (DQ) variants were also produced for comparison of both mechanical properties and wear characteristics. Compared to the DQ treatment, improved impact toughness and elongation to fracture were achieved with the DQ&P treatment while initial strength and hardness was reduced. An impeller-tumbler testing device was used to measure the impact-abrasive wear performance of the different experimental microstructures and compared with that of a reference commercial 500 HB steel. No advantage of the increased ductility of the DQ&P steels was apparent; wear resistance was shown to only correlate with the initial surface hardness of the steels

Effect of finish rolling and quench stop temperatures on impact-abrasive wear resistance of 0.35 % carbon direct-quenched steel

Abstract Novel high-hardness medium-carbon martensitic laboratory steel has been produced and tested for abrasive wear resistance. Different finish rolling temperatures (FRT) combined with either direct quenching (DQ) or interrupted quenching to 250 °C was applied to vary the content of retained austenite and hardness. The steel carbon content was set to 0.35 % to obtain a surface hardness of approximately 600 HB. Lowering the finish rolling temperature in the range 920–780 °C, i.e. into the non-recrystallization regime resulted in a more elongated prior austenite grain structure, which increased the hardness of the DQ variants without any significant loss of Charpy-V impact toughness. Although increasing the degree of autotempering by raising the quench stop temperature reduces the hardness of the martensitic microstructure, it was found that proper quenching stop temperature could be utilized to achieve balanced toughness and hardness properties. Impact-abrasive wear resistance as measured in impeller-tumbler tests with natural granite as the abrasive demonstrated that wear resistance increased with increasing surface hardness