This thesis covers improvements on the upperbounds for ropelength of a specific class of algebraic knots.

OMNeT++ is a discrete event, modular simulator often used for simulation of computer networks. The universal simulator can be extended by various packages, such as INET framework, which is used for simulation of devices and TCP/IP protocols. This thesis examines facilities of INET package in the routing that is dynamic routing protocols. Concretely, it aims at OSPF protocol for IPv6 networks (OSPFv3). The protocol is presented and its principles are interpreted. The work is designed to simulate the module OSPFv3 protocol and module is partially implemented.

This thesis investigates two aspects of the protocol IO-Link Wireless (IOL-W), a wireless derivative of the widely established network protocol for industry automation IO-Link (IOL). There is an increasing interest in using wireless solutions within the automation industry. The IOL-W protocol is developed to meet the needs of a wireless protocol that can meet the stringent reliability requirements of industrial applications. The first investigated aspect is whether it is feasible to port existing IOL stacks to IOL-W. The second aspect investigates the possibility to establish IOL-W communication using a generic hardware board supporting Bluetooth Low Energy (BLE) and IEEE 802.15.4, specifically the nRF architecture manufactured by Nordic Semiconductor. The properties and mechanisms of the physical layer of IOL-W are thoroughly researched. Afterward, two open-source IOL stacks are examined as potential candidates for protocol porting. From that examination, the main conclusion is that for a commercial project, it is more feasible to invest in a native IOL-W stack. Porting an IOL stack to IOL-W would be immensely time-consuming since it is not enough only to replace the code responsible for handling the physical layer. One would also need to modify the system management module embedded within every hardware layer. Lastly, the nRF hardware is examined, focusing on its radio capabilities. Several problems arose with the radio configuration and the CRC capability of the nRF boards from the subsequent investigation and experiments; therefore, it is concluded that this particular hardware is inappropriate for implementing IOL-W. / Den här uppsatsen granskar två aspekter av protokollet IO-Link Wireless (IOL-W), en trådlös version av det etablerade protokollet IO-Link (IOL). Det finns ett ökat intresse för trådlösa lösningar i Automationsindustrin och IOL-W protokollet är utvecklat för att bemöta det ökade behovet av pålitlig trådlös industriell kommunikation. Den första aspekten granskar huruvida det är möjligt att konvertera en IOL stack till en IOL-W stack. Den andra aspekten utreder om det är möjligt att etablera IOL-W kommunikation med hårdvara designad för Bluetooth Low Energy (BLE) och IEEE 802.15.4, mer specifikt, nRF arkitekturen tillverkad av Nordic Semiconductor. Egenskaperna och mekanismerna av "physical layer" av IOL-W är grundligt undersökt. Två IOL stackar har granskats och det har undersökts huruvida det med rimlig arbetsinsats går att konvertera någon av dem till IOL-W stackar. Undersökningen kommer att huvudsakligen konstatera att, för ett kommersiellt projekt är det bästa alternativet att investera i en färdig IOL-W stack. Att konvertera en IOL stack till en IOL-W stack är en tidskonsumerande uppgift och kräver grundlig kännedom i både IOL och IOL-W, att ersätta dom nedre lagren av en IOL stack är inte en rekommenderad lösning, eftersom System management modulen kommer att behövas modifieras, då den är inbyggd i varje lager av abstraktions modellen. Till sist, kommer nRF hårdvaran att examineras, fokus kommer att ligga på radions förmåga och kompabilitet. Under projektet gång dök ett flertal problem upp med radio konfigurationen samt CRC förmågan, detta kommer att presenteras med flertalet granskningar och experiment. Slutsatsen av undersökningen blir att nRF hårdvaran inte är lämplig att använda som bas för en implementation av IOL-W.

Sjöfartshögskolan i Kalmar har kurser i bl.a. programmerbara styrsystem. För att undervisningen ska ta steget in i Industri 4.0 vill skolan först ha utlåtande om svårighetsgraden att implementera en IO-linkgivare i befintlig process. Syftet med arbetet var att installera och konfigurera en IO-linkgivare i skolans ånganläggning för att på så sätt kunna utvärdera implementeringsarbetets svårighetsgrad. Detta sattes sedan i relation till att istället installera en traditionell analog tryckgivare. Genom att göra en installation och konfiguration implementerades IO-linkgivaren och för kontroll av funktion genomfördes en provning mot befintlig mätutrustning som referenser. Resultatet visade på en relativt komplicerad implementering men ett noggrant mätvärde samt många möjligheter utöver det. / The Maritime Academy in Kalmar wanted to learn about how the implementation of IO-link sensors in a steam process could be used in teaching. The work aimed to investigate how an IO-link sensor works and provide input to develop the content of the school's programming courses. This was done by first implementing a new pressure sensor (IO-Link) in a steam process and then performing the electrical installation in the existing automatic cabinet. In the control cabinet, the existing PLC system was expanded with an IO link master for communication between sensor and PLC system. The result was a fully functional IO link sensor that transferred the vapor pressure in the system to the PLC system. As the IO link sensor for this purpose does not use many of the functions that may be sought in an IO link sensor, it becomes an expensive and complicated installation. If the teaching and course content are developed to use more of the IO link donor's competence, it can justify a higher purchase price and a more complicated implementation.

As Twitter launched with their unique way of limiting posts to only 140 characters the usage of link shorteners was brought forth. This was the only way to fit long URLs in tweets until Twitter solved this by providing their own integrated link shortener. This study investigates how links are used on Twitter. The study include both care fulldata collection including multiple APIs and analysis of the collected data providing new insight into this topic. It was found that a small set of internet domains account for a large part of the links found in posted tweets. This set of top occurring domains did not necessarily reflect the top domains typically on common internet top lists. When looking at link shorteners in posted tweets we found that “bit.ly” was the most common one. Due to our method of collecting data we had the possibility of looking up the amount of clicks “bit.ly” links had received. We compared the click data to the amount of retweets the tweets containing these links had received and this led to some interesting discoveries regarding the ratio between these two.

The process of removing snow from the streets of cities in an optimal way can pose quite a challenge. In order to optimize the path of the snow removing vehicle, the city can be translated into a graph with nodes as crossings and links as roads. Once the city is modelled as a graph, all nodes with degree one can be eliminated and the snow removal time is added to the closest node. An optimization problem can then be solved in order to find a vehicle path in this reduced graph. The purpose of this thesis is to give an algorithm to reconstruct the reduced graph and then dictate the proper vehicle path in this reconstructed graph. The algorithm is constructed by reversing the node elimination process, piecing together the original graph and traversing the graph to get information about what to do on the eliminated links and nodes. The obtained algorithm is presented in this thesis.

This thesis proposes novel methods and comprehensive analysis for power loss calculation, DC-link current and voltage ripple estimation, and bus bar design in two-level three-phase voltage source inverters (VSIs). A novel method of MOSFET voltage rise- and fall-time estimations for the switching power loss calculation is developed. The estimation accuracy is significantly improved by the proposed method. In order to provide a reference for thermal management design, inverter power loss analysis is presented. Using the parameters obtained from the semiconductor device datasheets and inverter operating conditions, power loss calculations of three types of devices, namely IGBT, MOSFET, and diode, are discussed. The conduction power loss calculations for these three devices are straightforward; and, the switching power loss of IGBTs and diodes can be obtained from the energy losses given by datasheets. However, many MOSFET datasheets do not provide the switching energy losses directly. Therefore, to acquire MOSFET switching energy losses, switching transient times must be estimated as accurately as possible. The impacts of inverter anti-parallel diode reverse recovery on the DC-link current and voltage ripples are investigated. According to the analysis, the impact of diode reverse recovery on the voltage ripple is negligible, while the RMS value of current ripple is influenced by both diode reverse recovery and inverter switching frequency. A novel method is developed to calculate the ripple current RMS value and the estimation accuracy is significantly improved. Depending on the calculated current and voltage ripples, DC-link capacitor selection is introduced. Generally speaking, failures in the DC-link capacitors take place more frequently than the failures in other parts of the inverter system, and plenty of research has been focusing on minimizing the required DC-link capacitance. As a result, the accurate estimations of DC-link current and voltage ripples are vital in the optimization methods. In addition, with the accurate estimations, the over-design in the DC-link capacitance could be reduced. Finally, the design of a practical bus bar is presented. The DC current distribution is aff ected by the numbers and locations of the DC input tabs, while the AC current distribution is influenced by the numbers and locations of the installation holes for DC-link capacitors and semiconductor devices. Furthermore, parasitic parameters of the bus bar, especially the stray inductance and voltage spikes caused by this inductance during switching turn-o transients, are also discussed from the angle of the design rules and correlation between the parameters and bus bar geometry structure. In the end, a bus bar is designed with balanced current distribution and low stray inductance. / Thesis / Doctor of Philosophy (PhD)

The well known synthesis problem of obtaining dimensions of a four-link mechanism such that a point on the coupler link traces a desired path has been extensively studied. There are two types of path generation–path specified by a finite number of precision points where the prescribed points must be exactly traced, and continuous path generation where the path is approximately traced by the coupler point. In various application, more than one or multiple paths are required to be traced by the coupler point and in such cases, adjustable four-link mechanisms where one of the dimension or parameters of the mechanism can be changed is a possible solution. This thesis deals with the synthesis of planar and spherical adjustable four-link crank-rocker type mechanisms for multiple continuous path generation. Approximate multiple path generation is typically solved as an optimization problem where the dimensions and parameters of the four-link mechanism are obtained such that the objective functions, typically in terms of an error between the desired and obtained path, is minimized. In this thesis, we present a two-stage optimization to obtain four-link mechanism dimensions such that the adjustable four-link mechanism can approximately trace multiple desired paths. In the first stage, the parameters in the driving side of the four-link mechanism is obtained and in the second stage, the parameters of the driven side are obtained. In case of adjustable planar four-link mechanism, a novel optimization objective function based on circle-fitting is used and for spherical adjustable mechanisms a novel plane-fitting based objective function is used. The use of these objective functions results in a lesser number of variables to be searched and thus the method presented in this work is more efficient than existing optimization based algorithms available in literature. Several examples are presented for synthesis of adjustable planar and spherical four-link mechanism for tracing multiple paths. In particular, a spherical mechanism which can generate an oval and an‘ 8’shaped path by one single adjustment is synthesized. This mechanism has been made using 3D printing and it is shown that the mechanism indeed traces the desired oval and ‘8’ shaped paths. This mechanism is being planned for use in a flapping wing micro air vehicle where the oval shaped path is known to make the vehicle to move forward while the ‘8’ shaped path results in a hovering motion.

This thesis is concerned with the measurement of physical quantities. Thesis describes sensors in general terms and requirements, which delivers latest trends in the field of automation. The main theme of this thesis is sensors for meassuring pressure, and their connection to the automation chain. In the next part thesis describes the design of the converter for connecting SMART sensors for pressure measuring, that use HART communication protocol, to the automation systems managed by a communication protocol IO-link. First will be described in detail various communication standards by their ISO OSI model, and on this theoretical basis will be based design of converter between communication protocol HART and communication protocol IO-Link. The last part will be Designed software for this converter.

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