International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / End-to-End testing is a tool for verifying that Range Telemetry (TM) System Equipment will deliver satisfactory performance throughout a planned flight test. A thorough test verifies system thresholds while gauging projected mission loading all in the presence of expected interference. At the White Sands Missile Range (WSMR) in New Mexico, system tests are routinely conducted by Range telemetry Engineers and technicians in the interest of ensuring highly reliable telemetry acquisition. Even so, flight or integration tests are occasionally halted, unable to complete these telemetry checks. The Navy Standard Missile Program Office and the White Sands Missile Range, have proactively conducted investigations to identify and eliminate problems. A background discussion is provided on the serious problems with the launcher acquisition, which were resolved along the way laying the ground work for effective system testing. Since there were no provisions to test with the decryption equipment an assumption must be made. Encryption is operationally transparent and reliable. Encryption has wide application, and for that reason the above assumption must be made with confidence. A comprehensive mission day encrypted systems test is proposed. Those involved with encrypted telemetry systems, and those experiencing seemingly unexplainable data degradations and other problems with or without encryption should review this information.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / This paper describes techniques for error location analysis used in the design and testing of high-speed instrumentation data recording and communications applications. It focuses on the differences between common bit error rate testing and new error location analysis. Examples of techniques presented include separating bit and burst error components, studying probability of burst occurrences, looking at error free interval occurrence rates as well as auto-correlating error position. Each technique contributes to a better understanding of the underlying error phenomenon and enables higher-quality digital recording and communication. Specific applications in error correction coding emulation, magnetic media error mapping and systematic error interference are discussed.

In systems subjected to long-term loading, subcritical crack growth is the principal mechanism causing the time-dependent deformation and failure of rocks. Subcritical crack growth is environmentally-assisted crack growth, which can allow cracks to grow over a long period of time at stresses far smaller than their failure strength and at tectonic strain rates. The characteristics of subcritical crack growth can be described by a relationship between the stress intensity factor and the crack velocity. This study presents the results of studies conducted to validate the constant stress-rate test for determining subcritical crack growth parameters in Coconino sandstone, compared with the conventional testing method, the double torsion test. The results of the constant stress-rate test are in good agreement with the results of double torsion test. More importantly, the stress-rate tests can determine the parameter A with a much smaller standard deviation than the double torsion test. Thus the constant stress-rate test seems to be both a valid and preferred test method for determining the subcritical crack growth parameters in rocks. We investigated statistical aspects of the constant stress-rate test. The effects of the number of tests conducted on the subcritical crack growth parameters were examined and minimum specimen numbers were determined. The mean and standard deviation of the subcritical crack growth parameters were obtained by randomly selecting subsets from the original strength data. In addition, the distribution form of the subcritical crack growth parameters and the relation between the parameter n and A were determined. We extended the constant stress-rate test technique to modes II and III subcritical crack growth in rocks. The experimental results of the modes I, II and III tests show that the values of the subcritical crack growth parameters are similar to each other. The subcritical crack growth parameter n value for Coconino sandstone has the range of 34 to 38 and the parameter A has the range of 1.02x10⁻² to 6.52x10⁻² m/s. The effect of confining stress, specimen size, and water saturation on subcritical crack growth under mode II loading has also been investigated. Finally strength parameters for Coconino sandstone were determined experimentally, including tensile strength, uniaxial compressive strength, cohesion, internal friction angle, in-plane / our-of-plane shear strength and the fracture toughness under mode I, II, and III loading.

Ceramics have been widely used for personnel and vehicle armour because of their desirable properties such as high hardness and low density. However the brittle nature associated with the ceramic materials, i.e. low toughness, reduces their ability to withstand multiple ballistic hits. The present work is focused on ceramic armour materials made from alumina and zirconia toughened alumina (ZTA). The effects of grain size and zirconia phase transformation toughening on the mechanical and high strain rate properties in both materials were investigated in detail. Alumina, 10%, 15% and 20% nano ZTA with 1.5 mol% yttria stabiliser were produced with various grain sizes. The processing of the materials started from suspension preparation, spray freeze drying of the suspension and die pressing to produce homogeneous green bodies with densities above 54%. Then, the green bodies were sintered using conventional single stage and/or two stage sintering to produce the samples with full density and a range of grain sizes (0.5 to 1.5 µm alumina grains and 60 to 300 nm zirconia grains). The effects of the processing conditions on the microstructures were studied and the optimum processing route for each sample was determined. The mechanical properties of the alumina and ZTA samples were investigated, including Vickers hardness, indentation toughness, 4-point bend strength and wear resistance. The results showed that, with an increasing amount of zirconia addition, evident increases of the toughness, strength and wear resistance properties were observed, whilst the hardness reduced slightly correspondingly. The effect of density and grain sizes on the hardness and toughness were studied as well: larger alumina grain size led to a higher hardness and negligible change in toughness, whilst the zirconia grain coarsening enhanced the phase transformation toughening effect and the samples displayed a higher toughness. In addition to the investigation of the mechanical properties, the alumina and nano ZTA samples were subjected to high strain rate testing, including split Hopkinson pressure bar (SHPB) (8-16 m/s) and gas gun impact testing (100-150 m/s). The high strain rate performances were compared in terms of their fracture behaviours, fragmentation process and fragment size distribution. Raman spectroscopy was used to measure the amount of zirconia phase transformation in ZTA samples after the high strain rate testing. The residual stress and dislocation density in alumina grains after testing were quantitatively measured using Cr3+ fluorescence spectroscopy. The results indicated that zirconia phase transformation can reduce the residual stress and dislocation densities in the ZTA samples, resulting in less damage, lower plastic deformation and less crack propagation. In addition, a nano zirconia material with 1.5 mol% yttria stabiliser (1.5YSZ) was subjected to a gas gun impact test with a very high impact speed (142 m/s); a deep projectile penetration was observed, due to the low hardness of the pure zirconia, whilst the sample stayed intact. The result further confirmed that the zirconia phase transformation toughening effect can improve the sample's high strain rate performance.

O aumento de demanda por combustíveis menos poluentes e de fontes renováveis faz com que o Etanol se destaque como uma alternativa as fontes convencionais de energia. O crescente aumento no consumo deste produto, para os próximos anos, exigirá meios de transporte e estocagem eficientes e seguros, desde os diversos produtores até os terminais de distribuição. O transporte por dutos é, sem dúvida, a forma mais econômica de transporte deste produto, porém, há evidências de que esses dutos de transporte e fundo de tanques de armazenamento de etanol poderiam ser susceptíveis ao fenômeno de corrosão sob tensão. Este fenômeno pode ser avaliado, por exemplo, por ensaios de baixa taxa de deformação (BTD) com corpos de prova com ou sem entalhe. Este trabalho tem por objetivo avaliar a influência da severidade do entalhe em corpos de prova ensaiados a baixa taxa de deformação no meio etanol combustível simulado (PRCI SFGE). Foram preparados quatro tipos de corpos de prova de aço API X70: sem entalhe, com entalhe da norma NACE TM 0111, com entalhe “intermediário” (severidade 18,9% menor que o da norma) e com entalhe “menos severo” (redução de 37,2% na severidade do entalhe, segundo concentração de tensões, quando comparado com o da norma). Os resultados mostram que os quatro tipos de corpos de prova apresentaram susceptibilidade ao meio (etanol PRCI SFGE). Nos corpos de prova sem entalhe esta susceptibilidade foi evidenciada somente nas imagens fractográficas. Já nos CPs com entalhe, mesmo com redução de concentrações de tensões no entalhe, observou-se resultados bem semelhantes, ficando evidenciada a susceptibilidade ao meio tanto nas imagens fractográficas (fratura frágil), quanto pela diminuição da ductilidade. / The increasing demand for cleaner fuels and renewable sources makes the ethanol rise as an alternative to conventional energy sources. The increasing consumption rate of this product, predicted for the upcoming years, will require safer and more efficient methods for transportation and storage through the entire transport cycle. Pipelines are the most economical way to transport it. However, there is evidence that pipeline transportation and the bottom of the storage tanks for ethanol might be susceptible to the stress corrosion cracking phenomenon. This phenomenon can be assessed by slow strain rate tests (SSRT) using smooth or notched specimen. This work aims to evaluate the influence of notch severity in specimens submitted to SSRT technique in simulated fuelgrade ethanol (PRCI SFGE). Four types of specimens of steel API X70 were prepared: unnotched, notched according to standard NACE TM 0111, notched with “intermediate” severity (severity 18.9% lower than the standard) and “less severe” notched (reduction of 37.2% on severity of the notched when compared with the standard). The results show that both sample types presented susceptibility in the solution (ethanol PRCI SFGE). For the unnotched specimens this susceptibility was observed only in fractographic images. In the notched specimens, despite the reduction of stress concentrations in the notch, the results were very similar. In this case the susceptibility can be observed in fractographic images (brittle fracture) as well as by decrease in the ductility.

O aumento de demanda por combustíveis menos poluentes e de fontes renováveis faz com que o Etanol se destaque como uma alternativa as fontes convencionais de energia. O crescente aumento no consumo deste produto, para os próximos anos, exigirá meios de transporte e estocagem eficientes e seguros, desde os diversos produtores até os terminais de distribuição. O transporte por dutos é, sem dúvida, a forma mais econômica de transporte deste produto, porém, há evidências de que esses dutos de transporte e fundo de tanques de armazenamento de etanol poderiam ser susceptíveis ao fenômeno de corrosão sob tensão. Este fenômeno pode ser avaliado, por exemplo, por ensaios de baixa taxa de deformação (BTD) com corpos de prova com ou sem entalhe. Este trabalho tem por objetivo avaliar a influência da severidade do entalhe em corpos de prova ensaiados a baixa taxa de deformação no meio etanol combustível simulado (PRCI SFGE). Foram preparados quatro tipos de corpos de prova de aço API X70: sem entalhe, com entalhe da norma NACE TM 0111, com entalhe “intermediário” (severidade 18,9% menor que o da norma) e com entalhe “menos severo” (redução de 37,2% na severidade do entalhe, segundo concentração de tensões, quando comparado com o da norma). Os resultados mostram que os quatro tipos de corpos de prova apresentaram susceptibilidade ao meio (etanol PRCI SFGE). Nos corpos de prova sem entalhe esta susceptibilidade foi evidenciada somente nas imagens fractográficas. Já nos CPs com entalhe, mesmo com redução de concentrações de tensões no entalhe, observou-se resultados bem semelhantes, ficando evidenciada a susceptibilidade ao meio tanto nas imagens fractográficas (fratura frágil), quanto pela diminuição da ductilidade. / The increasing demand for cleaner fuels and renewable sources makes the ethanol rise as an alternative to conventional energy sources. The increasing consumption rate of this product, predicted for the upcoming years, will require safer and more efficient methods for transportation and storage through the entire transport cycle. Pipelines are the most economical way to transport it. However, there is evidence that pipeline transportation and the bottom of the storage tanks for ethanol might be susceptible to the stress corrosion cracking phenomenon. This phenomenon can be assessed by slow strain rate tests (SSRT) using smooth or notched specimen. This work aims to evaluate the influence of notch severity in specimens submitted to SSRT technique in simulated fuelgrade ethanol (PRCI SFGE). Four types of specimens of steel API X70 were prepared: unnotched, notched according to standard NACE TM 0111, notched with “intermediate” severity (severity 18.9% lower than the standard) and “less severe” notched (reduction of 37.2% on severity of the notched when compared with the standard). The results show that both sample types presented susceptibility in the solution (ethanol PRCI SFGE). For the unnotched specimens this susceptibility was observed only in fractographic images. In the notched specimens, despite the reduction of stress concentrations in the notch, the results were very similar. In this case the susceptibility can be observed in fractographic images (brittle fracture) as well as by decrease in the ductility.

O aumento de demanda por combustíveis menos poluentes e de fontes renováveis faz com que o Etanol se destaque como uma alternativa as fontes convencionais de energia. O crescente aumento no consumo deste produto, para os próximos anos, exigirá meios de transporte e estocagem eficientes e seguros, desde os diversos produtores até os terminais de distribuição. O transporte por dutos é, sem dúvida, a forma mais econômica de transporte deste produto, porém, há evidências de que esses dutos de transporte e fundo de tanques de armazenamento de etanol poderiam ser susceptíveis ao fenômeno de corrosão sob tensão. Este fenômeno pode ser avaliado, por exemplo, por ensaios de baixa taxa de deformação (BTD) com corpos de prova com ou sem entalhe. Este trabalho tem por objetivo avaliar a influência da severidade do entalhe em corpos de prova ensaiados a baixa taxa de deformação no meio etanol combustível simulado (PRCI SFGE). Foram preparados quatro tipos de corpos de prova de aço API X70: sem entalhe, com entalhe da norma NACE TM 0111, com entalhe “intermediário” (severidade 18,9% menor que o da norma) e com entalhe “menos severo” (redução de 37,2% na severidade do entalhe, segundo concentração de tensões, quando comparado com o da norma). Os resultados mostram que os quatro tipos de corpos de prova apresentaram susceptibilidade ao meio (etanol PRCI SFGE). Nos corpos de prova sem entalhe esta susceptibilidade foi evidenciada somente nas imagens fractográficas. Já nos CPs com entalhe, mesmo com redução de concentrações de tensões no entalhe, observou-se resultados bem semelhantes, ficando evidenciada a susceptibilidade ao meio tanto nas imagens fractográficas (fratura frágil), quanto pela diminuição da ductilidade. / The increasing demand for cleaner fuels and renewable sources makes the ethanol rise as an alternative to conventional energy sources. The increasing consumption rate of this product, predicted for the upcoming years, will require safer and more efficient methods for transportation and storage through the entire transport cycle. Pipelines are the most economical way to transport it. However, there is evidence that pipeline transportation and the bottom of the storage tanks for ethanol might be susceptible to the stress corrosion cracking phenomenon. This phenomenon can be assessed by slow strain rate tests (SSRT) using smooth or notched specimen. This work aims to evaluate the influence of notch severity in specimens submitted to SSRT technique in simulated fuelgrade ethanol (PRCI SFGE). Four types of specimens of steel API X70 were prepared: unnotched, notched according to standard NACE TM 0111, notched with “intermediate” severity (severity 18.9% lower than the standard) and “less severe” notched (reduction of 37.2% on severity of the notched when compared with the standard). The results show that both sample types presented susceptibility in the solution (ethanol PRCI SFGE). For the unnotched specimens this susceptibility was observed only in fractographic images. In the notched specimens, despite the reduction of stress concentrations in the notch, the results were very similar. In this case the susceptibility can be observed in fractographic images (brittle fracture) as well as by decrease in the ductility.

No description available.

In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of microstructure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under Open Circuit Potential (OCP) and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate (1×10-6 s-1) in 1 wt% and 3.5 wt% NaCl solutions under OCP condition. It was confirmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.

V předložené práci se zabýváme problematikou stochastického modelování úro- kových sazeb. Jedním z nejobvyklejších postup· je modelovat dynamiku úroko- vých sazeb pomocí stochastické diferenciální rovnice difúze, jejímiž základními kameny jsou funkce driftu a funkce difúze. Od 70. let 20. století byla navržena celá řada model· tohoto typu, a ačkoli se tyto modely neustále zdokonalují, vyvstává přirozená otázka, zda se historicky pozorované úrokové sazby skutečně takovými difúzními rovnicemi řídily. V této práci budeme právě uvedenou hypo- tézu testovat pro několik nejběžnějších jednofaktorových model· úrokové sazby první generace. Z historických dat odhadneme obecnou momentovou metodou a metodou maximální věrohodnosti parametry jednotlivých difúzních rovnic a následně provedeme statistické testy dobré shody proložení těchto rovnic pozo- rovanými daty. 1