Metakaolin is a pozzolanic material with the potential to reduce permeability and chloride ingress; however, quantification of the effects of metakaolin use on the cracking sensitivity of concrete mixtures is needed to ensure that these improvements in performance are not compromised. This study was conducted to investigate the early age cracking potential due to restraint stresses from incorporating metakaolin in concrete. Calorimetry testing showed that metakaolin was more sensitive to temperature than mixtures with only Portland cement. Results showed more shrinkage, less stress relaxation, and higher restraint stress from the inclusion of metakaolin, potentially increasing cracking sensitivity of mixtures. 1 This section was published in Construction and Building Materials[57]. Permission is included in Appendix A

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Main goals of this diploma thesis is to chart methods used to secure wireless internet networks a test those methods through attack on access point of wireless network with target to receive password to access this network and decryption of captured packets. For charting of types of security measures used for wireless network, I performed a series of measurements in field on different places in Czech Republic and Germany. Primary purpose of mesurements performed in Germany is caomparison of results from Germany with results from Czech Republic. Also, I tried to crack the security measures i controlled environment. Due to illegality of this experiment I used my own network and network that belongs o one of my friends who agreed with the experiment.In the end is the presentation of results of field measurements and cracking attempts along with some tips for network security.

Stress corrosion cracking (SCC) of alloy 600 is regarded as one of the most important challenges to nuclear power plant operation worldwide. This study investigates two heats of alloy 600 (forged control rod drive mechanismnozzle and rolled divider plate) in order to obtain a better understanding of the effects of the material parameter on the SCC phenomenon. The experimental approach was designed to determine the effect of the manufacturing process (forged vs. rolled), the cold-work (as-received vs. cold-worked) and the strain path (monotonic vs. complex) on SCC of alloy 600. Specimens with different strain paths have been produced from two materials representative of plant components and tested in high temperature (360°C) high pressure primary water environment. The manufacturing process has been proven to have a great effect on the stress corrosion cracking behaviour of alloy 600. Indeed, the SCC susceptibility assessment has demonstrated that the rolled materialis resistant to SCC even after cold work, whereas the forged material is susceptible in the as-received state. Microstructural characterisations have been undertaken to explain these differences in SCC behaviour. The carbide distribution is the main microstructural parameter influencing SCC but the misorientation, in synergy with the carbide distribution, has been proven to give a better representation of the materials SCC susceptibilities.

The objective of this research is to determine the thermal residual stresses and strains in bonded composite repairs on cracked metal structures. This work is an essential contribution to a fatigue damage initiation model for bonded composite repair, where knowledge of the initial stress/strain state after an elevated temperature cure is important. Furthermore, this work is an elementary part for the development of a generic certification approach to bonded composite repairs. Accounting properly for thermal residual stresses in test specimens and in real applications will assist in determining the true feasibility of a bonded composite repair. The objective of this work was realized in four stages of research. In the first stage, seven AMRL sandwich type composite bonded repair specimens were manufactured, of which one was instrumented by placing 44 strain gauges at eight planar locations and within five different interfaces. Residual strains at ambient temperature (including both thermal residual strains and other process induced strains) were measured during the manufacturing process. In the second stage, the stress free temperature for the repaired specimen was experimentally determined and the thermal residual strains measured as a function of operating temperature. In the third stage, a theoretical analysis was carried out to estimate the thermal residual stress and strain distributions in various bonded repairs. This analysis also addressed the effect of symmetrical disbonds around the crack. Finally, a finite element analysis was carried out to assess the limitations of the theoretical analysis as well as to provide a more detailed insight into the complex thermal residual stress and strain state of the AMRL sandwich type specimen. During this work it was found that high thermal residual strains (reaching 15% of the yield strain) are present in the bonded repair specimen at ambient temperature. Previous analysis schemes predicted results nearly 60% higher. The thermal residual strain versus temperature measurement showed that only very small changes in thermal residual strains occurred above 90°C leading to a defined effective stress free temperature of 85.8°C for the employed adhesive FM 73M. By utilizing an effective stress free temperature, a linear-elastic approach was used to model thermal residual stresses and strains in composite bonded repairs. Major achievements in the theoretical analysis include a linear-elastic closed form solution for tapered joints and reinforcements without the need for a numerical solution scheme, a stress field prediction ahead of the crack tip for the metal substrate of a bonded repair based on a concise complete solution of the classical fracture mechanics problem of a center crack in an infinite plate and, an extended Rose model for the prediction of the stress intensity factor of a bonded repair with symmetrical disbonds showing the severity of thermal residual stresses especially for partially disbonded composite repairs to cracked metal specimens. The key to precise predictions of thermal residual stresses in bonded composite repairs is the knowledge of the adhesive behaviour at elevated temperatures under thermal residual stress loading. A generic type specimen is presented which allows to investigate the relevant adhesive behaviour. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Orientador: Antonio Marsaioli Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T16:21:01Z (GMT). No. of bitstreams: 1 Vilalba_FabiodeAlbuquerque_M.pdf: 570013 bytes, checksum: 8f4e3f0349848d620390519a1dc8eee4 (MD5) Previous issue date: 2003 / Resumo: O cupuaçu (Theobroma grandiflorum) é uma fruta nativa da região amazônica Brasileira cujas sementes convenientemente fermentadas, secas e torradas podem ser utilizadas para a obtenção de um produto similar ao chocolate. Uma etapa deste processo deverá também envolver, portanto, a obtenção dos nibs (cotilédones fragmentados) das amêndoas secas, separando-o da casca e do gérmen, o que pode ser feito antes ou após a torração. Esta fase do processamento da amêndoa é, ainda, realizada manualmente, de modo totalmente artesanal e pouco eficiente. O objetivo deste trabalho consistiu em pesquisar uma forma alternativa de quebra da amêndoa seca sem torrar, realizada através de um beneficiador de cilindros, seguida da utilização de um jogo de peneiras para a separação das frações. Os fatores estudados no rendimento da obtenção dos nibs e na verificação de sua pureza (percentual de casca e gérmen) foram a umidade da amêndoa inteira e a velocidade diferencial do par de cilindros de borracha do beneficiador, sendo este último a diferença das velocidades tangenciais destes cilindros. Os valores estudados das umidades foram de 5, 6 e 7%. O fator velocidade diferencial foi estudado em duas faixas, a primeira com 2,10 , 2,66 e 3,23m/s e, a segunda, com 0,84 , 1,87 e 3,23m/s. Pelos resultados obtidos, foi verificado que a variável umidade apresenta a maior influência na quebra das amêndoas. O nível de umidade de 5% da amêndoa inteira apresentou os maiores rendimentos de obtenção de nibs. A velocidade diferencial não apresentou diferença significativa nos rendimentos. Em relação aos valores dos percentuais de casca e gérmen nos nibs, nenhuma variável em estudo apresentou influência significativa nos valores desta resposta, mesmo assim todos os resultados foram bastante satisfatórios. Os percentuais de casca e gérmen encontrados no material final (nibs) foram inferior a 1,75%. O rendimento deste processo alternativo está em torno de 90% de obtenção dos cotilédones encontrados em uma determinada massa de amêndoas. Concluindo, o processo proposto constitui uma alternativa mecanizada, tecnicamente válida e superior aos métodos artesanais, apresentando bom rendimento de recuperação dos nibs, com percentuais de casca e gérmen abaixo do tolerado / Abstract: Cupuassu (Theobroma grandiflorum) is a native fruit from the Brazilian Amazon region whose seeds suitably fermented, dried and roasted can be used to manufacture a product similar to chocolate. One phase of this process must also include, therefore, the extraction of nibs (scrapped cotyledons) from the dried kernels, separating it from the shells, what can be done before or after roasting. This part of processing the kernels is still done through manual operation, in an inefficient artisan way. This work aims at devising an alternative way of cracking the dried but not roasted kernels by using a roller crusher, followed by sieving for separating the fractions. The variables studied for determining the nibs acquisition yield as well the purity of such material (expressed as percentage of shell and embryo fragments) were the moisture of the whole kernel and the differential speed of the double rollers of the crusher, this last is the difference of the tangential speeds of those rollers. The studied values of the moisture were 5, 6 e 7%. The factor differential speed was studied in two bands, the first with 2.10 , 2.66 e 3.23m/s, the second with 0.84 , 1.87 e 3.23m/s. The results confirmed that the moisture of the whole kernel was the variable that most influenced the cracking of the kernels. The moisture level of 5% of the whole kernels showed greater yield obtainment of nibs. The variation of the differential speed did not present any significant difference at yield. With regard to the percentage values of shell and embryo found in nibs, the variables considered did not show any significant difference on the response parameter, although the results were very much satisfactory. The percentage of shell and embryo found in the final material (nibs) is below the 1.75%. The yield of this alternative process is 90% of the cotyledons acquisition from certain kernels mass. In conclusion, the proposed process sets up as a mechanized alternative, of technical value and superior to the artisan methods, showing good nibs acquirement yield, and percentage of shells and embryo below the tolerated. / Mestrado / Mestre em Engenharia de Alimentos

The continuous population increase in recent years requires a greater number of households to be built quickly, with good materials and produced under quality standards that guarantee their manufacturing process. The prefabricated concrete, produced and supplied by concrete plants, is poured into the different structural elements, the mezzanine slabs being the most careful surfaces in the appearance of fissures; because being horizontal and having larger dimensions, the dimensional changes in the concrete appear more frequently due to the rapid loss of water from the surface of the concrete before setting; which generates superior stresses to the resistant capacity of the concrete at early ages, which affect the durability and reduce the resistance of the structures, causing greater economic expenses in maintenance and repairs. In the present investigation, 5%, 10% and 15% of rice husk ash was used as a replacement for cement and 900g/m3 of polypropylene fiber; The results indicate that as the percentage of rice husk ash increases, there is a reduction in the slump and the crack fissures, and that the resistance to compression and flexion decreases, with respect to the concrete pattern.

This thesis describes a process of cracking a password, existing types of attacks and generating passwords using probabilistic grammar. This grammar can be used as an attack that works on the basis of learning from an existing list of passwords and generating them by using constructed context-free grammar from the learning phase. The core of this thesis is the design and implementation of distribution solution for this type of attack. Implementation includes refactoring of existing solution and optimization to maximize use of every available resource.

The susceptibility to solidification cracking of unstabilized and stabilized ferritic stainless steels was investigated using self-restrained Houldcroft, Modified Varestraint-Transvarestraint (MVT), and hot tensile testing. Five experimental steel grades comprising an unstabilized, two mono stabilized (Ti or Nb), and two dual stabilized (Ti + Nb), and two commercial unstabilized and a dual stabilized (Ti + Nb), and another dual stabilized containing-Mo alloy (nine different alloys in total) were used in this study. Seven steel grades comprising an unstabilized, two mono stabilized (Ti and Nb) respectively, three dual stabilized (Ti + Nb) and a dual stabilized containing Mo were used for the self-restrained Houldcroft method. Autogenous gas tungsten arc welding at a speed of 6 mm/s, 3 mm/s, and 1 mm/s was done. The unstabilized ferritic stainless steel was resistant to solidification cracking. Ti addition to ferritic stainless steel resulted in a minor increase to susceptibility to solidification cracking. Nb in ferritic stainless steel increased solidification cracking. The addition of Ti and Nb resulted in a decreased susceptibility to solidification cracking compared to an alloy containing only Nb. The weld metal microstructures were a mixture of columnar and equiaxed grains. The interdendritic crack surfaces were enriched in Nb, Ti, Mn, Si, Al, Mn, and Mo. The MVT test was used for the test of an unstabilized, a Nb stabilized and two (Ti + Nb) dual stabilized ferritic stainless steels. Two different welding speeds of 6 mm/s and 3 mm/s using autogenous gas tungsten arc welding were employed. The high content (Ti + Nb) steel at a welding speed of 3 mm/s had the greatest sensitivity to solidification cracking. The Nb stabilized steel at both welding speeds (6 mm/s and 3 mm/s) and high content (Ti + Nb) steel at a welding speed of 6 mm/s showed intermediate sensitivity to solidification cracking. The unstabilized and low content (Ti + Nb) grades were the least sensitive to solidification cracking. The weld metal microstructures transverse to the welding direction revealed columnar grains in all the samples for both welding speeds. Three experimental Ti-, Nb-, and dual Ti + Nb stabilized ferritic stainless steels were used for hot tensile testing using a Gleeble-1500D thermo-mechanical machine at testing temperatures of 1200°C, 1250°C, and 1300°C. The dual stabilized ferritic stainless steel showed a high and fairly constant hot ductility with an increasing testing temperature. The Ti stabilized alloy revealed a slightly lower ductility compared to the dual stabilized steel but much higher ductility than the Nb stabilized ferritic stainless steel. The SEM images of the intergranular cracking showed interdendritic morphologies. EDX analysis showed the elements Al, Mn, Ti, Si, Ni, S, Nb, and Ni to be associated with the fractured surfaces. The hot tensile test results were inconclusive, due to the small number of samples and an acquisition frequency that was too low. The MVT test was better than the self-restrained Houldcroft, and the self-restrained Houldcroft was better than the hot tensile tests in quantifying the susceptibility of a specific ferritic stainless steel alloy to solidification cracking. The cracking response of Houldcroft seemed to be dominated by welding speed. Cracking response of MVT test seemed to be dominated by the Nb content. The effect of Nb and Ti on the susceptibility cracking could be explained in terms of the effect of these two alloying elements on the difference between the liquidus and the solidus. Nb was found to segregate strongly to the grain boundaries (low k value) which resulted in a significant increase in the difference between the liquidus and the solidus. This difference increased BTR which results in a high susceptibility to solidification cracking. Ti has a higher k value and segregates less than Nb during solidification. / Thesis (PhD)--University of Pretoria, 2018. / Materials Science and Metallurgical Engineering / PhD / Unrestricted

This thesis deals with illegal distribution of programs. It describes methods of licencing programs and ways their restrictions. It focuses on description basic tools and techniques used to program cracking. Farther this work describes structure of executables files on MS Windows. The work is completed with malware analysis for clarification techniques masking of code. This work is complemented by a demonstration application for program code masking.