Maintenance cost is one of the important issues in railway heavy-haul operations. In most of the cases, these costs are majorly referring to reprofiling and changing the wheels of the locomotives and the wagons. The main reason of the wheel damages is usually severe wear and/or surface initiated rolling contact fatigue (RCF).This work tries to enhance and improve the knowledge of the wheel wear and RCF prediction models using dynamic simulations. While most of the contents of this study can be generalised to other operational networks, this study is focused on the locomotives and wagons of the Swedish iron-ore company LKAB. The trains are operating on the approximately 500 km long IORE line from Luleå to Narvik in the north of Sweden and Norway respectively.Firstly, a literature survey of dynamic modelling of the wagons with various three-piece bogie types is presented. Then, with concentrating on the standard three-piece bogies, parameter studies are carried out to find out what the most important reasons of wheel damages are. Moreover, the long-term stability of wheel profiles of the IORE wagons is analysed. This is done by visualising the wear and RCF evolution on the wheel profiles over 150,000km of simulated running distance.Most of the calculations for the wagons are repeated for the locomotives. However, traction and braking are also considered in the simulation model and their effects on wheel damages are briefly studied. To improve the accuracy of the wheel damage analysis, a newly developed algorithm called FaStrip is used to solve the tangential contact problem instead of FASTSIM. The damage prediction model developed in the thesis is used to study the effects of increasing axle load, correcting the track gauge, limiting the electro-dynamic braking and using a harder wheel material on the wheel life. Furthermore, a new method is developed to predict the running distance between two consecutive reprofilings due to severe surface initiated fatigue. The method is based on shakedown analysis and laboratory tests.Most of the research works in wear calculation are limited to two approaches known as wear number and Archard methods. The correlation between these two methods is studied. The possibility of using the relation between the two methods for the wear calculation process is investigated mainly to reduce the calculation time for wheel profile optimisation models. / <p>QC 20171219</p>

Living organisms are made up of a multitude of individual cells that are surrounded by biomolecules and fluids. It is well known that cells are highly regulated by biochemical signals; however it is now becoming clear that cells are also influenced by the mechanical forces and mechanical properties of the local microenvironment. Extracellular forces causing cellular deformation can originate from many sources, such as fluid shear stresses arising from interstitial or blood flow, mechanical stretching during breathing or compression during muscle contraction. Cells are able to sense variations in the mechanical properties (elasticity) of their microenvironment by actively probing their surroundings by utilizing specialized proteins that are involved in sensing and transmitting mechanical information. The actin cytoskeleton and myosin-II motor proteins form a contractile (actomyosin) network inside the cell that is connected to the extracellular microenvironment through focal adhesion and integrin sites. The transmission of internal actomyosin strain to the microenvironment via focal adhesion sites generates mechanical traction forces. Importantly, cells generate traction forces in response to extracellular forces and also to actively probe the elasticity of the microenvironment. Many studies have demonstrated that extracellular forces can lead to rapid cytoskeletal remodeling, focal adhesion regulation, and intracellular signalling which can alter traction force dynamics. As well, cell migration, proliferation and stem cell fate are regulated by the ability of cells to sense the elasticity of their microenvironment through the generation of traction forces. In vitro studies have largely explored the influence of substrate elasticity and extracellular forces in isolation, however, in vivo cells are exposed to both mechanical cues simultaneously and their combined effect remains largely unexplored. Therefore, a series of experiments were performed in which cells were subjected to controlled extracellular forces as on substrates of increasing elasticity. The cellular response was quantified by measuring the resulting traction force magnitude dynamics. Two cell types were shown to increase their traction forces in response to extracellular forces only on substrates of specific elasticities. Therefore, cellular traction forces are regulated by an ability to sense and integrate at least two pieces of mechanical information - elasticity and deformation. Finally, this ability is shown to be dependent on the microtubule network and regulators of myosin-II activity.

This master’s thesis describes the structural design of pallet conveyor for the transport pallet unit between the ground floor and upper storey of warehouse buildings, according to given technical parameters. The work includes design and functional solution for driven roller track. It solves lifting of frame cage and roller track and the pallet unit, using traction gearless drive. There is used cable transfer 2:1. Frame cage is equipped with a mandatory safety gear. The design is verified strength calculations of the frame lift and frame cage. Part of the thesis is the drawing documentation.

This thesis describes the design of a laboratory model of the bridge crane, which will be further used for Internal Combustion Engines to identify the forces in and verificationof control algorithms, automated crane. The aim of this thesis is to design a bridge and a cat laboratory bridge crane with a carrying capacity of 10 kg and work area 2 m x 2 m x 3 m crane mostly of lightweight aluminum profiles. Furthermore, it includes variousdrives and drive for the lifting mechanism.

This project developed within the engineering studies of M-STG submits a proposal of a production technology of production of the magnet holder made of DC03. Based on a literary study of the problem of cutting, drawing, bending and calculations manufacturing of the component in a production die was suggested. The production die uses a normalised component and is tightened on PE 100 crank press with nominal drawbar pull 1000 kN. The conclusion of the thesis deals with the economic benefit of the suggested manufacturing technology.

Maintenance cost is one of the important issues in railway heavy haul operations. For the iron-ore company LKAB, these costs are mainly associated with the reprofiling and changing of the wheels of the locomotives and wagons. The main reason for the wheel damages is usually surface initiated rolling contact fatigue (RCF) on the wheels.The present work tries to enhance and improve the knowledge of the vehicle-track interaction of the Swedish iron-ore freight wagons and locomotives used at Malmbanan. The study is divided into two parts. Firstly, it is tried to get into the roots of RCF using the simulation model of the iron ore wagon (Paper A). Secondly, the study is focused on predicting wear and RCF on the locomotive wheels also via a dynamic simulation model (Paper B).In the first paper, some key issues of the dynamic modelling of the wagons with three piece bogies are first discussed and then parameter studies are carried out to find the most important reasons of wheel damages. These parameter studies include track design geometry, track irregularities, wheel-rail friction level, cant deficiency and track stiffness. The results show a significant effect of the friction level on the amount of RCF risk.As the locomotive wheel life is much shorter than that of the wagons, LKAB has decided to change the locomotive wheel profile. Two final wheel profiles are proposed; however, one had to be approved for the field tests. In the second paper, the long term evolution of the two profiles is compared via wear simulation analysis. Also, the RCF evolution on the wheel profiles as a function of running distance is discussed. The process is first carried out for the current locomotive wheel profiles and the results are compared with the measurements. Good agreement is achieved. Finally, one of the proposed profiles is suggested for the field test because of the mild wear and RCF propagation. / <p>QC 20150210</p>

Now a days, the society thinks about more sustainable and clean energy sources. Most of the countries in the world relay on non-renewable energy sources for the generation of electricity. This results in the scarcity of fossil fuels in future and also increases the production of carbon emissions. This thesis considers a metro system named Kochi Metro which is a rapid transit system serving in the city of Kochi in Kerala, India which uses renewable sources, mainly solar, for giving power to the Metro.In this thesis work, trying to analyze the measures adopted by Kochi Metro Rail project in potential reductions of energy consumption and energy generation both contributing to energy efficiency.With the help of Matlab, different levels of installed PV power are used to find out the possible self-usage, self-sufficiency, and energy neutrality of the system.

The phenomenon of fake news has a significant impact on our social life, especially in the political world. Fake news detection is an emerging area of research. The sharing of infor-mation on the Web, primarily through Web-based online media, is increasing. The ability to identify, evaluate, and process this information is of great importance. Deliberately created disinformation is being generated on the Internet, either intentionally or unintentionally. This is affecting a more significant segment of society that is being blinded by technology. This paper illustrates models and methods for detecting fake news from news articles with the help of machine learning and natural language processing. We study and compare three different feature extraction techniques and seven different machine classification techniques. Different feature engineering methods such as TF, TF-IDF, and Word2Vec are used to gener-ate feature vectors in this proposed work. Even different machine learning classification al-gorithms were trained to classify news as false or true. The best algorithm was selected to build a model to classify news as false or true, considering accuracy, F1 score, etc., for com-parison. We perform two different sets of experiments and finally obtain the combination of fake news detection models that perform best in different situations.

Cytoskeletal tension plays an important role in numerous biological functions of adherent cells, including mechanosensing of the cell’s microenvironment, mechanotransduction, cell spreading and migration, cell shape stability, and in stem cell lineage. It is believed that for normal biological functions the cell must maintain its cytoskeletal tension stable, at a preferred set-point level, under external perturbations. This is known as tensional homeostasis. Any breakdown of tensional homeostasis is closely associated with disease progression, including cancer, atherosclerosis, and thrombosis. The exact mechanism and the relevant environmental conditions for the maintenance of tensional homeostasis are not yet fully understood. This thesis investigates the impacts of substrate stiffness, availability of functional cadherin junctions and steady shear stress on tensional homeostasis of cells and cell clusters. We define tensional homeostasis as the ability of cells to maintain a consistent level of tension with low temporal traction field fluctuations. Traction forces of isolated cells, multicellular clusters, and monolayer are measured using micropattern traction microscopy. Temporal fluctuations of the traction field are calculated from time-lapsed traction measurements. Results demonstrated that substrate stiffness, cadherin cell-cell junctions and shear stress all impact tensional homeostasis. In particular, we found that stiffer substrates promoted tensional homeostasis in endothelial cells, but were detrimental to tensional homeostasis in vascular smooth muscle cells. We also found that E-cadherins were essential for tensional homeostasis of gastric cancer cells and that extracellular and intracellular mutations of E-cadherin had domain-specific effects on tensional homeostasis. Finally, laminar flow-induced shear stress led to increased traction field fluctuations in endothelial cell monolayers, contrary to reports of physiological shear promoting vascular homeostasis. A possible reason for this discrepancy might be the limitation of our approach which could not account for mechanical balance of traction forces in the monolayers. Through the exploration of these environmental factors, we also found that tensional homeostasis was a length scale-dependent and cell type-dependent phenomenon. These insights suggest that future studies need to take a more comprehensive approach and aim to make observations of different cell types on multiple length scales, in order decipher the mechanism of tensional homeostasis and its role in (patho)physiology. / 2021-08-30T00:00:00Z

The mass-market adoption of electrification in the transportation sector mandates stringent and aggressive requirements in terms of cost, power rating, efficiency, power density, and specific density of power electronics. Modular packaging of power electronics is advantageous and thus ubiquitously used by the automotive industry. A trend of shrinking die sizes and increased integration is evident and will inevitably continue. The thermal management system has become ever more significant as it is one of the main obstacles to higher power densities. The cooling system must be cost-effective, simple, efficient, reliable, and compatible with system requirements. Pin fins are a reliable and effective means of augmenting heat transfer. They rely on inducing turbulence, increasing the effective wetted surface, and accelerating fluid velocity. Unavoidably the pin fin array also produces an undesirable pressure drop that is commensurate to the pumping power required for the system. In this thesis, a tool is developed for the geometry optimization of pin fin arrays to dissipate the heat at a rate large enough to ensure junction temperatures do not exceed the maximum value possible at a minimal pressure drop. It is hoped that this tool would contribute to the multi-physics optimization and integration of power electronics for electrified vehicles. This optimization is confined to equalaterally spaced short pin fins, aspect ratios less than three. The tool employs empirical correlations since flow is too complex to solve analytically and numerical solutions or CFD-simulations are too time and computationally extensive. The tool development is done in a comprehensive manner. Starting from the first principles of a two-level voltage source inverter's operation. Next, the inevitable power losses from the operation are explained and a method for their calculations is presented. Correlations in the literature related to both pressure drop and heat transfer are reviewed afterward. Then the methodology of the construction of the tool is explicated in detail. Employing a commercial power module to benchmark results; three scenarios with different flow rates and inlet temperatures are optimized for. Simulations in ANSYS Fluent are run to verify the accuracy of correlations used in the tool. Comparing the optimized geometry of pin fins to the original benchmarking geometry it is evident that employing this tool on a per-application basis provides superior performance. / Thesis / Master of Applied Science (MASc)