A comparison of structure and properties of S355J2H steel after a heat treatment in a tunnel furnace or in a walking beam furnace

Import 23/08/2017Tato bakalářská práce se zabývá porovnáním výsledných hodnot meze pevnosti, meze kluzu, tažnosti a absorbované energie včetně metalografických vlastností a chemického složení trubek reálných zakázek, vyrobených na středisku Malý Mannesmann provozu Válcovna trub- TŘINECKÉ ŽELEZÁRNY a.s. (dále jen Válcovna trub) v závislosti na typu normalizační pece. Jako zkoumaný materiál byla vybrána ocel „C“ jakosti S355J2H. Zcela náhodně byly vybrány rozměry trubek o průměru 88,9 mm a 114,3 mm, oba ve stěnách 8,8 mm, 14,2 mm a 22,2 mm. Pro potřeby vyhodnocení mikrostruktury byla použita přeražená tělesa zkoušky rázem v ohybu, kde byly porovnány parametry jako je podíl fází, velikost zrna, rovnoměrnost struktury a řádkovitost.This bachelor thesis deals with the comparison of the resulting values of the ultimate tensile strength, yield strength, elongation at fracture and absorbed energy including metallographic properties and chemical composition of the real orders pipes produced at the Small Mannesmann plant of the Válcovna trub- TŘINECKÉ ŽELEZÁRNY a.s. (hereinafter referred to as the Válcovna trub) depending on the type of the normalization annealing furnace. The "C" grade steel S355J2H was selected as the material under investigation. The dimensions of tubes with a diameter of 88.9 mm and 114.3 mm, both in the walls 8.8 mm, 14.2 mm and 22.2 mm, were randomly selected. For the purpose of evaluating the microstructure, the fractured bodies were used from notch toughness test, where parameters such as phase proportion, grain size, structure uniformity and degree of banding were compared.636 - Katedra materiálového inženýrstvívýborn

Development of Quenching and Tempering of C110 and T95 Steels According to API 5CT

Diplomová práce se zabývá vývojem zušlechtění jakostí C110 a T95 vyrobených z oceli s označením C95/110. Cílem je dosažení mechanických hodnot stanovených normou API 5CT vhodným režimem tepelného zpracování. Jedná se tedy o dosažení hodnot meze pevnosti v tahu, meze kluzu, tažnosti a tvrdosti. Tento vývoj probíhal na provoze Válcovny trub-TŘINECKÉ ŽELEZÁRNY a.s., konkrétně na středisku Velký Mannesmann. Předmětem zkoumání byly trubky o rozměrech 244,48 x 11,05 mm a 269,88 x 21,06 mm ve dvou různých tavbách v každém rozměru, které plně vyhovovaly chemickému složení daném výše uvedenou prováděcí normou. Celkem bylo pro tento výzkum vyrobeno 14 ks trub. K vyhodnocení mikrostruktury byly z trubek odebrány vybrané vzorky jak po kalení, tak i po popouštění pro obě jakosti.These Diploma thesis deals with the development of the quenching and tempering of the steels C110 and T95 made of the steel with the designation C95/110. The aim is to achieve the mechanical properties required by the API 5CT standard by an appropriate heat treatment mode. It is therefore the achievement of tensile strength, yield strength, elongation at fracture and hardness values. This development was carried out on the Válcovna trub-TŘINECKÉ ŽELEZÁRNY a.s., namely the Large Mannesmann centre. The subject of the investigation were tubes with dimensions of 244.48 x 11.05 mm and 269.88 x 21.06 mm in two different heats in each dimension which were fully conform to the chemical composition given in the abovementioned implementing standard. In total, 14 pieces of tubes were produced for this research. To evaluate the microstructure, selected samples were taken from the tubes both after quenching and after tempering for both steel grades.636 - Katedra materiálového inženýrstvívýborn

Adaptive Aggregation of Flow Records

This paper explores the problem of processing the immense volume of measurement data arising during network traffic monitoring. Due to the ever-increasing demands of current networks, observing accurate information about every single flow is virtually infeasible. In many cases the existing methods for the reduction of flow records are still not sufficient enough. Since the accurate knowledge of flows termed as "heavy-hitters" suffices to fulfill most of the monitoring purposes, we decided to aggregate the flow records pertaining to non-heavy-hitters. However, due to the ever-changing nature of traffic, their identification is a challenge. To overcome this challenge, our proposed approach - the adaptive aggregation of flow records - automatically adjusts its operation to the actual traffic load and to the monitoring requirements. Preliminary experiments in existing network topologies showed that adaptive aggregation efficiently reduces the number of flow records, while a significant proportion of traffic details is preserved

Securing Distributed Computer Systems Using an Advanced Sophisticated Hybrid Honeypot Technology

Computer system security is the fastest developing segment in information technology. The conventional approach to system security is mostly aimed at protecting the system, while current trends are focusing on more aggressive forms of protection against potential attackers and intruders. One of the forms of protection is also the application of advanced technology based on the principle of baits - honeypots. Honeypots are specialized devices aimed at slowing down or diverting the attention of attackers from the critical system resources to allow future examination of the methods and tools used by the attackers. Currently, most honeypots are being configured and managed statically. This paper deals with the design of a sophisticated hybrid honeypot and its properties having in mind enhancing computer system security. The architecture of a sophisticated hybrid honeypot is represented by a single device capable of adapting to a constantly changing environment by using active and passive scanning techniques, which mitigate the disadvantages of low-interaction and high-interaction honeypots. The low-interaction honeypot serves as a proxy for multiple IP addresses and filters out traffic beyond concern, while the high-interaction honeypot provides an optimum level of interaction. The proposed architecture employing the prototype of a hybrid honeypot featuring autonomous operation should represent a security mechanism minimizing the disadvantages of intrusion detection systems and can be used as a solution to increase the security of a distributed computer system rapidly, both autonomously and in real-time

Comparison of Filter Techniques for Two-Step Feature Selection

In the last decade, the processing of the high dimensional data became inevitable task in many areas of research and daily life. Feature selection (FS), as part of the data processing methodology, is an important step in knowledge discovery. This paper proposes nine variation of two-step feature selection approach with filter FS employed in the first step and exhaustive search in the second step. The performance of the proposed methods is comparatively analysed from the stability and predictive performance point of view. As the obtained results indicate the choice of the filter FS in the first stage has strong influence on the resulting stability. Here, the choice of univariate Pearson correlation coefficient based FS method appears to provide the most stable results

Agent-Based Model of the Spectrum Auctions with Sensing Imperfections in Dynamic Spectrum Access Networks

Cognitive radio (CR) is the underlying platform for the application of dynamic spectrum access (DSA) networks. Although the auction theory and spectrum trading mechanisms have been discussed in the CR related works, their joint techno-economic impact on the efficiency of distributed CR networks has not been researched yet. In this paper we assume heterogeneous primary channels with network availability statistics unknown to each secondary user (SU) terminal. In order to detect the idle primary user (PU) network channels, the SU terminals trigger regularly the spectrum sensing mechanism and make the cooperative decision regarding the channel status at the fusion center. The imperfections of the spectrum mechanism create the possibility of the channel collision, resulting in the existence of the risk (in terms of user collision) in the network. The spectrum trading within SU network is governed by the application of the sealed-bid first-price auction, which takes into account the channel valuation as well as the statistical probability of the risk existence. In order to maximize the long-term payoff, the SU terminals take an advantage of the reinforcement comparison strategy. The results demonstrate that in the investigated model, total revenue and total payoff of the SU operator (auctioneer) and SU terminals (bidders) are characterized by the existence of the global optimum, thus there exists the optimal sensing time guaranteeing the optimum economic factors for both SU operator and SU terminals

Robot-Based Image Analysis for Evaluating Rehabilitation after Brain Surgery

After certain types of brain surgery, patients are often affected by changes in both their dynamic balance and facial disorder. Because rehabilitation takes several months, it is important that both doctors and patients are able to monitor progress quantitatively. At present, such quantification is subjective and highly dependent on the doctor’s opinion. Thus, we here investigate the use of robot-based image analysis for measuring rehabilitation. To evaluate a patient’s dynamic balance, we developed a mobile robotic platform that uses a stereovision camera (MS Kinect) to capture a video of the subject walking along a hospital corridor. To evaluate a patient’s facial disorders, the same camera is used in a static mode to detect and capture precise facial movements that the subject is asked to perform. From these videos, specific patterns can be extracted for rehabilitation process description