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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Application of acoustic emission for surface roughness definition

Hajtman, Benjamín January 2019 (has links)
The surface quality or surface layer properties significantly affect the reliability and durability of component operations. The surface is described as a border which separates more objects or substances from each other. There are various types of tools which can be used to evaluate surface texture. A completely new method which helps to evaluate the surface roughness is the application of acoustic emission. In the experimental part were measured several surfaces of various materials by the set of acoustic emission and a gauge with a diamond tip. The recording was accomplished by two sensors, namely IDK-09 and MTPA-5. The results of the measurement were described, and the method is considered to be particularly successful when applied to hard materials.
2

Technologie výroby a zpracování středověkých hrotů střel / Technology of manufacture and treatment of medieval arrowhead

Kašpar, Jan January 2010 (has links)
This thesis analyses issue of manufacture, typology and use of medieval arrowheads. In theoretical part describe historical evolution of bow and his archaeological discovery in Europe, especially from medieval times. After that is revealed historical evolution of arrowheads and describe their typology. In next chapters are mentioned ways of iron production, mainly in early medieval times and also describe technology of manufacture different types of arrowheads. There is a characterization of medieval arrow, his construction and characteristics. Continuously in this background research are revealing questions of penetration depend on the various types of arrowheads, which are testing on the most known types of armour like chainmail or breast plate. In experimental part of this paper are metallographicaly analyzing archaeological discoveries from the early and late medieval times. Conclusions about their manufacturing, treatment and possibilities of use are built on knowledge about arrowheads structures, hardness and shapes.
3

Hardware Root of Trust for Linux Based Edge Gateway

Al-Galby, Mohamed, Arezou, Madani January 2018 (has links)
Linux-based Edge Gateways that connects hundreds or maybe thousands of IoT devices, are exposed to various threats and cyber-attacks from the internet. These attacks form a considerable risk targeting the privacy and confidentiality of IoT devices throughout their gateways. Many researches and studies have been conducted to alleviate such a problem. One of the solutions can be achieved by building a root of trust based on a hardware module such as Trusted Platform Module (TPM) or software like Trusted Execution Environment (TEE). In this work, we provide a solution to the problem by enabling Hardware Root of Trust (HRoT) using TPM on a product from HMS Industrial Network AB known as GWen board, a Linux-based embedded system, used as gateway to connect IoT devices. We describe a method that uses the processor of the GWen (i.e. Zynq-7020 FPGA SoC) to enable secure boot. Besides, we provide a method to enable the TPM chip mounted on the GWen (i.e. SLB 9670 TPM 2.0) using TPM Software Stack TSS 2.0. We demonstrated, in detail, various use-cases using the TPM on GWen including cryptographic keys generation, secure key storage and key usage for different cryptographic operations. Furthermore, we conducted an analysis to the adopted solution by inspecting the latency of TPM commands on the GWen gateway. According to the high restrictions of TPM 2.0 specifications and based on our results, adding the TPM 2.0 to the IoT gateway GWen will enhance the security of its Linux distribution and will makes it possible to securely identify and authenticate the gateway on the network based on its secret keys that are stored securely inside its TPM.
4

Progresivní zařízení pro tvorbu mikrovtisků / Progressive Device for Micro-Dents Generating

Sedlačík, Jan January 2013 (has links)
The diploma thesis deals with an engineering design, a realization and a calibration of a apparatus for surface texturing of test samples. Microdents are produced by a diamond tool pressing. Electromagnetic linear actuator is used for pressing. Translation and rotation of the sample are secured by a couple of stepping motors. Thanks to this the apparatus can produce texture with well defined and easily controlled geometry. The diploma thesis contains a summary of surface texturing methods, designs of constructional variations, a electronic device of the apparatus and the calibration are also included.
5

Vizuální detekce elektronických součástek / Visual detection of electronic devices

Juhas, Miroslav January 2010 (has links)
This thesis describes application of image processing for precise distance measurement in self acting production of a tip for AFM microscopes. The main goal is to measure distances between assembly parts during fabrication process. The purpose is to acquire a data for self acting assembly line which have to substitute inaccurate and nonrecurring manual assembly process. The assembly process consists of three technological steps. In first two steps the tungsten wire is glued to the cantilever. Distance measurement is necessary in all axes for proper alignment of parts. In third step the sharp tip is etched by KOH solution. The right distance between liquid level and the cantilever must be kept. A camera with high resolution and macro objective is used to acquire an image. Camera image is then calibrated to suppress distortions and scene position with respect to camera position. Length conversion coefficient is also computed. Object recognition and distance measurement is based on standard computer vision methods, mainly: adaptive thresholding, moments, image statistics, canny edge detector, Hough transform… Proposed algorithms have been implemented in C++ using Intel OpenCV library. The final achieved distance resolution is about 10µm per pixel. Algorithm output was successfully used to assembly few test tips.

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