Application for secure data storage for mobile devices

Bakalářská práce je zaměřena na vytvoření aplikace pro bezpečné ukládání dat do paměti mobilních zařízení. Teoreticky jsou popsány operační systémy podle oblíbenosti u uživatelů a programovací jazyky. V další části práce je vysvětlen šifrovací standard AES a jeho princip šifrování a dešifrování dat. V praktické části je vytvořen program PINapplication. Aplikace umožní uživateli ukládat jeho citlivá data pod svým zvoleným heslem. Uložená citlivá data je možno libovolně odebírat a přidávat nová. Data vložená uživatelem jsou zašifrována standardem AES. Celá tato aplikace je naprogramována v jazyce Java ve verzi pro mobilní zařízení (J2ME).This bachelor’s thesis is focused on the creation of application for secure data storage for mobile devices. The paper theoretically describes operating system according to users popularity and programming languages. The following section explains AES encryption standard and its principle of data encryption and decryption. In the practical part is created a PINapplication programm. The application allows user to store sensitive data using chosen password. It is possible to save new data or erase current data. These data are encrypted by mentioned AES standard. The application is programmed in Java language with the version for mobile devices (J2ME).

The Impact of Wireless Microphone Technologies on Film Making

Tato diplomová práce se zaměřuje na vývoj bezdrátových mikrofonních technologií ve filmové tvorbě. Během posledních několika desetiletí prošly bezdrátové mikrofonní technologie rapidním vývojem, který dramaticky ovlivnil způsob, jakým jsou filmy vytvářeny a vnímány. Práce začíná historickým přehledem bezdrátových mikrofonních systémů, sleduje jejich evoluci od prvotních rádiových systémů až po moderní digitální technologie. Popisuje i překážky související s používáním těchto technologií, jako je například otázka interference a regulace rádiového spektra. Dále se věnuje významným zvukařům, kteří použitím bezdrátových mikrofonů v raných fázích jejich vývoje rozšířili možnosti práce s filmovým zvukem. Cílem této práce je poskytnout komplexní přehled o vývoji a významu bezdrátových mikrofonních technologií ve filmové tvorbě a přispět tak k lepšímu porozumění této klíčové oblasti audiovizuální produkce

Network service testing with WAN network emulator and load simulators

Cílem diplomové práce bylo prostudovat požadavky různých telekomunikačních služeb na parametry sítě, která jsou zpoždění, ztrátovost, propustnost, kolísání zpoždění atd. Provést testování těchto služeb pomocí emulátoru rozsáhlé sítě WAN a simulátoru zátěže. Dále prostudovat jednotlivé TCP algoritmy a provést jejich vyhodnocení ze strany propustnosti. V první části diplomové práce je popsána kvalita služeb QoS pro hlasovou komunikaci VoIP, videokonverzaci, streamované audio, video a pro data. V další části najdeme, jaké druhy zpoždění vznikají od odesílatele přes mezilehlá zařízení, přenosová média až k příjemci. Třetí kapitola popisuje aplikaci NetDisturb. Je to aplikace, která dokáže emulovat reálné vlastnosti datové sítě a umí přicházející provoz ovlivnit například zpožděním paketů, ztrátovostí, omezit šířku pásma atd. Tématem dalších části je TCP protokol a TCP algoritmy. Jsou zde uvedeny základní vlastnosti TCP protokolu, mechanismy předcházející zahlcení a analýza jednotlivých TCP algoritmů. V praktické části jsou vytvořeny dvě laboratorní úlohy. První laboratorní úloha se zabýva kvalitou služeb QoS pro různé druhy provozu. Druhá laboratorní úloha provádí analýzu TCP algoritmů z hlediska jejich propustnosti.The main task of this thesis was to explore the requirements of different telecommunications services on the network parameter, that are packet delay, packet loss, throughput, jitter. Make to test network service with WAN network emulator and load simulators. Next focus was to explore TCP congestion avoidance algorithms and focus on their throughput. The purpose of the first chapter is to introduce Quality of Service (QoS) for VoIP, video conversation, streaming audio, streaming video and data. The second chapter are to explore various types of delay, that are created from the sender through network device, transmission media to the recipient. The third chapter is to introduce NetDisturb application. It is application, that can emulate real properties of the data network and incoming traffic affect example packet delay, packet loss, bandwidth limit and so on. The key objectives of the fourth and fifth part is TCP protocol and TCP congestion avoidance algorithms. Hier are to introduce TCP protocol basic properties, congestion avoidance mechanisms and analysis of TCP congestion avoidance algorithms. In the practical part are created two laboratory exercises. First laboratory exercise is designed on the implementation QoS for various types of traffic. Second laboratory exercise is focused on the analysis TCP congestion avoidance algorithms and their throughput.

THE INFLUENCE OF A SHRINKAGE REDUCING ADMIXTURE ON THE LONG-TERM DEVELOPMENT OF DYNAMIC PROPERTIES IN ALKALI-ACTIVATED SLAG

The paper investigates the way a shrinkage-reducing admixture affects the long-term development of dynamic properties in mortars made with alkali-activated slag (AAS). Two AAS mortars were tested - one contained a shrinkage-reducing admixture, the other did not. The specimens (prisms of 40 × 40 × 160mm) were observed for changes in the dynamic modulus of elasticity at ages of 3 days through 2 years using the ultrasonic pulse velocity test and the resonance method. Even though the statistical analysis of the results gave no proof that the shrinkage-reducing admixture affected the final values, the development of the elastic modulus appeared to follow a very interesting trend which is completely different from trends commonly observed in cement-based composites

ANALYSIS OF THE INFLUENCE OF TRANSDUCER FREQUENCY ON THE ULTRASONIC MEASUREMENT OF CONCRETE HOMOGENEITY

The paper analyses the influence of transducer frequency on the determination of concrete homogeneity using the ultrasonic pulse velocity test. Transit time measurements were made on a 590×590mm concrete slab, with 110mm in thickness, in a raster of 5×5 points, which means the slab was tested in 25 places. The tests were made using a Pundit PL-200 ultrasonic tester using transducers set at 54, 82, and 150 kHz. Two types of measurements were performed – spot measurements of the ultrasonic pulse transit time at each point and full area scanning. The paper is concluded by an evaluation of the concrete slab’s homogeneity measured by different transducers and techniques in addition to a statistical analysis of how the results are affected by the transducer frequency

EXPERIMENTAL ANALYSIS FOCUSED ON THE MATERIAL CHARACTERISTICS OF THE CEMENT-BASED POLYMER-MODIFIED MORTARS

The article deals with the experimental analysis focused on the development of the physical and mechanical characteristics of the cement-based polymer-modified mortars (PCM) during ageing. Two different commercial products commonly used for similar in-situ applications were used for the experiment. The results of the shrinkage, elastic, fracture and strength parameters determined within the time interval from 3 days to 2 years of ageing are summarized and discussed in the article. The performed experimental analysis showed different behaviour of tested PCMs. The most significant differences were observed at the age of 90 days when one of the tested PCM showed a substantial decrease in most of investigated characteristics

Monitoring the internal structure behaviour of alkali-activated slag paste: effect of the curing mode

This paper deals with the monitoring of the internal structure behaviour of an alkaliactivated slag (AAS) paste. The slag was activated with a 4M solution of sodium hydroxide. The behaviour of the internal structure of the paste was regularly monitored through the changes in the resonant frequency and the mechanical properties, until the paste reached the age of 90 days. The main aim of the article is to show the long-term maturation and degradation process of an AAS paste under different curing modes. The results obtained suggest that the curing mode of the specimens has a significant effect on the behaviour of the internal structure of the paste based on the AAS. The development of both the dynamic properties and the flexural strength indicates the occurrence of a higher porosity in the internal structure of the paste, especially when the free drying process is started earlier. Insufficient hydration of the binder system is also a likely cause of cracks. The reduction in the relative dynamic moduli values ranging from 50 % to 80 % was observed for drying specimens at the age of 90 days. What is very interesting is that the occurrence of cracks was not prevented even by intensive moist curing of the paste as, between the 21st and the 28th day of maturing, there was a significant decrease of about 20 % in the relative dynamic modulus of elasticity and also a 50 % reduction in the flexural strength

Influence of the gripping fixture on the modified compact tension test results: evaluation of the experiments on cylindrical concrete speciments

The modified compact tension test (MCT) might become in the future a stable test configuration for the evaluation of fracture-mechanics parameters or also for description of fatigue behavior of composites materials such as concrete. Core drilling is used for sampling of existing structures. These samples have cylindrical shape with the selected thickness to avoid the stress concentration. This contribution focuses on the evaluation of the fracture behavior during static and quasi static tests. Static tests are performed on standard specimen with diameter 150 mm and length 300 mm. The quasi-static tests are performed using two different gripping fixtures. The results for quasi-static tests are represented as L-COD diagrams (i.e. load vs. crack opening displacement) measured on the loading axis. The comparison of results and discussion of advantages and disadvantages are introduced

Determination of the static modulus of elasticity of cement mortars in the early stage of ageing

The paper deals with the influence of the composition of cementitious materials on the development of their modulus of elasticity in the early stage of ageing. The primary goal of the paper is to determine the static modulus of elasticity of cement mortars almost from the beginning of their setting. Four cement mortars were produced for the experiment. They differed only in the water/cement ratio and in the amount of plasticizer. All mortars were subjected to continuous measurement of the dynamic modulus of elasticity for 24 hours from the moment of their pouring into the moulds. The measurement involved the ultrasonic pulse velocity method. In addition, the static modulus of elasticity was determined at the mortar age of 24 hours. The results are presented in table and graphical forms