Mechanical Behavior of Pipeline Steels and an Al0.1CoCrFeNi High-Entropy Alloy

This dissertation is composed of two parts. The first part focuses on the mechanical behavior study on pipelines steels. More specifically, the effect of hydrogen on the deformation behavior of the crack tip of an X52 pipeline steel specimen, and the overload effects on the fatigue crack growth of an x70 pipeline weld metal are discussed. For the second part of the dissertation, fatigue behavior of an Al0.1CoCrFeNi high-entropy alloy (HEA) is studied, and the influence of heat treatment is discussed. The objectives of the first part of this proposed work are to (1) detect the influence of hydrogen on the crack-tip deformation of compact-tension (CT) pipeline steel specimens; (2) understand effects of residual stress and plastic zone during crack growth, and obtain a comprehensive understanding of overload effects on the fatigue crack growth of the pipeline steels. In order to address those objectives, fatigue-crack-growth experiments have been performed to precrack the pipeline steel samples. In-situ neutron experiments were performed on both as-received and hydrogen-charged samples to detect the influence of hydrogen. In-situ synchrotron experiments have been performed to characterize the strain/stress field evolution during loading-unloading and the plastic-zone evolution during deformation. An overload has been applied during the synchrotron measurements and the overload effects on the strain/stress field around the crack tip have been investigated. The objectives of the second part of this proposed work are to (1) investigate the fatigue behavior of the Al0.1CoCrFeNi HEA (2) study the influence of heat treatment on the fatigue behavior of the Al0.1CoCrFeNi HEA. To address these objectives, tension-tension fatigue tests have been performed on as-Hiped and heat-treated samples. Failed samples were characterized by OM, SEM, EBSD, and TEM to identify deformation mechanisms and the influence of heat treatment. In conclusion, with the completion of the two parts of study, we now have a better understanding of fatigue and fracture mechanisms of both pipeline steels and HEAs, which can provide insights into the future design of steel pipelines, as well as the possible engineering applications for the HEAs

Biología pesquera de la pota gigante Dosidicus gigas en aguas exteriores a la Zona Económica Exclusiva de Chile

The jumbo flying squid Dosidicus gigas is widely distributed in the eastern Pacific Ocean and supports an important fishery. Although many studies have been carried out on the biology of this species, limited biological information is available in the waters outside the Exclusive Economic Zone of Chile (EEZ) (20°S-41°S and 74°30’W-84°W). Three surveys were conducted in this area by the Chinese squid jigging vessels during the period from April 2006 to May 2008. The majority of the catch in the survey was from the two areas defined by 37°30’-41°S and 78°30’-80°W and by 25°-30°S and 76°-77°30’W. The sex ratio (M: F) of the catch was 1: 2.48. The mean mantle length (ML) was 376 mm for males with a range of 257-721 mm and 388.7 mm for females with a range of 236-837 mm. Two distinguished size classes, medium- and large-sized groups, were identified in this study with the medium-sized group (350-450 mm ML) consisting of 89% of the total catch. The sizes at first sexual maturity were 638 mm ML for females and 565 mm ML for males. This study suggests that all the individuals examined were hatched from March 2007 to February 2008, indicating that D. gigas might spawn all year around with a peak spawning time from November 2007 to January 2008. Most of the stomachs analyzed had food remains. The preys included three major groups: fish (mainly lanternfish), cephalopods and crustaceans, but D. gigas was the dominant species in the stomach contents, showing strong evidence of cannibalism. The information obtained from this study improves our understanding of the fishery biology of D. gigas off Chile.La pota gigante Dosidicus gigas está ampliamente distribuida en el océano Pacífico oriental y soporta una pesquería importante. Aunque se han realizado muchos estudios sobre la biología de esta especie, la información existente para aguas externas a la Zona Económica Exclusiva (ZEE) de Chile (20ºS-41ºS y 74º30’W-84ºW) es muy limitada. Los barcos poteros chinos realizaron tres campañas en esta área entre abril de 2006 y mayo de 2008. La mayoría de las capturas en esas campañas proceden de dos áreas definidas por las coordenadas 37º31’S-41ºS 78º30’W-80ºW y 25ºS-30ºS 76ºW-77º30’W, respectivamente. La relación sexual (M:H) en las capturas fue de 1:2.48. La longitud media del manto (LM) fue de 376 mm para los machos con un rango que varió entre 257 y 721 mm, y de 388.7 mm para las hembras (236-837 mm). Se diferenciaron dos clases de tamaño: un grupo medio, cuya LM varió entre 350 y 450 mm representando un 89% de la captura total, y un grupo grande. La talla de primera maduración sexual fue de 638 mm para las hembras y de 565 mm para los machos. Este trabajo sugiere que todos los individuos examinados habían nacido entre marzo de 2007 y febrero de 2008, lo cual indica que D. gigas puede frezar durante todo el año, habiendo existido un pico de puesta desde noviembre de 2007 hasta enero de 2008. La mayoría de los estómagos analizados contenían restos. Las presas incluyen tres grandes grupos de organismos: peces (principalmente mictófidos), cefalópodos y crustáceos. Sin embargo, D. gigas fue la presa dominate en los contenidos estomacales, lo cual es una evidencia del fuerte canibalismo existente en esta especie. La información que se deriva de este trabajo mejora nuestro conocimiento sobre la biología de D. gigas frente a Chile

Modelos lineales generalizados bayesianos para la estandardización de CPUE: aplicación a la pesquería de calamar mediante jigging en el Pacífico noroccidental

Generalized linear Bayesian (GLBM) non-hierarchical and hierarchical models were developed for standardization of catch per unit effort (CPUE). The GLBM containing the covariates of month, latitude, sea surface temperature (SST), sea surface salinity (SSS) and sea level height (SLH) had the best fit for the Chinese squid-jigging fishery of Ommastrephes bartramii in the northwest Pacific Ocean based on deviance information criteria. This best-fitting model tends to be more ecologically sound than other CPUE standardization models, such as generalized linear models and generalized additive models. GLBM was also used to deal with the problems of estimating stock abundance index (i.e. standardized CPUE) resulting from increased spatial heterogeneity of spatial dynamics of fishing efforts in the squid fishery by predicting the standardized CPUE for unfished areas. The standardized CPUE based on data including predicted CPUE of unfished areas was lower than the derived CPUE based on data with observed CPUE alone, in particular during the fishing peak of August to October. This study indicates that it is more appropriate to use the standardized CPUE derived from data including both predicted CPUE of unfished areas and observed CPUE of fished area as a stock abundance index. We suggest that the proposed method be used in CPUE standardization to account for impacts of large spatial heterogeneity of fishing efforts in fisheries.Se desarrollan modelos lineales generalizados bayesianos (GLBM) jerárquicos y no-jerárquicos para la estandardización de captura por unidad de esfuerzo (CPUE). El modelo GLBM seleccionado para la pesquería del calamar Ommastrephes bartramii mediante jigging en el Pacífico noroccidental incorporó las variables explicativas mes, latitud, temperatura superficial del mar (SST), salinidad superficial del mar (SSS) y altura del nivel del mar (SLH). La selección del modelo se basó en el Criterio de Información de la Desviación (DIC). El modelo que mejor se ajustó a los datos tiene más sentido ecológico comparado con modelos de estandardización de CPUE basado en modelos lineales generalizados y modelos aditivos generalizados. Se utilizó también el GLBM para tratar el problema de la estimación de un índice de abundancia del stock (es decir, CPUE estandardizada) frente a la elevada heterogeneidad espacial en la dinámica del esfuerzo en la pesquería del calamar mediante la predicción de la CPUE estandardizada en áreas no pescadas. La CPUE estandardizada en base a los datos que incluyen la CPUE predicha en áreas no pescadas fue inferior a la CPUE derivada en base solamente a la CPUE observada, especialmente durante el pico de pesca de Agosto a Octubre. Este estudio muestra que es más apropiado usar la CPUE estandardizada derivada de datos que incluyen al mismo tiempo la CPUE predicha de las áreas no pescadas y la CPUE observada en el área pescada como índice de abundancia del stock. Se sugiere que se use el método propuesto para la estandardización de CPUE teniendo en cuenta la gran heterogeneidad espacial del esfuerzo pesquero

Identificación de las especies: Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis e Illex argentinus (Ommastrephidae) a través de medidas morfológicas de sus picos

Four oceanic squid species, Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis and Illex argentinus, not only support important commercial fisheries, but also play a vital role in their marine ecosystems. It is therefore important to identify them in the analyses of their predators’ stomach contents as this can yield critical information on the trophic dynamics of ecosystems. Hard beaks of the four species frequently found in their predators’ stomachs can be used to identify them. In this study, to remove the effect of size differences among individuals, measurements of upper and lower beaks were standardized with an allometric model. A discriminant analysis was carried out to compare morphological differences among the four species and between the sexes for each species. The upper rostral width and upper rostral length showed the greatest interspecific variation in the beak morphological variables of the four Ommastrephidae. The linear discriminant functions of beak morphological variables were developed for the four Ommastraphidae, which resulted in a rate of correct species classification of over 97%. Sexual dimorphism was also found in the beak morphology of O. bartramii and I. argentinus. This study suggests that morphological variables can be used to reliably classify Ommastrephidae at genus level, which can help identify the specie in the stomachs of cephalopod predators. This helps to improve the understanding of the role cephalopods play in their marine ecosystems.Las cuatro especies de calamares: Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis e Illex argentinus, sometidas a una importante presión pesquera, juegan un papel significativo dentro de los ecosistemas marinos a los que pertenecen. Al ser los picos de estas especies resistentes, las medidas de diversos aspectos de su morfología pueden servir para identificarlas en análisis de contenidos estomacales de sus depredadores. Ello permite obtener una información crucial sobre la dinámica trófica de los ecosistemas. En el presente estudio, las medidas realizadas en los picos superior e inferior de los Ommastrephidae se han normalizado mediante un modelo de crecimiento alométrico, para evitar la influencia del efecto tamaño de los individuos. A continuación, mediante un análisis discriminante, se han estudiado las diferencias morfológicas entre las cuatro especies, así como entre machos y hembras. Las medidas que presentaban mayores variaciones eran la anchura y longitud del rostro superior. Mediante funciones discriminantes lineales de las medidas morfológicas normalizadas de sus picos, se han conseguido clasificar las cuatro especies de Ommastraphidae, con una fiabilidad superior al 97%. Asimismo, a través de sus medidas morfológicas, se ha encontrado un claro dimorfismo sexual en los picos de O. bartramii e I. argentinus. El presente estudio sugiere que las medidas morfológicas pueden ser útiles para clasificar correctamente los Ommastrephidae a nivel de género, y puede permitir identificar la especie en contenidos estomacales de depredadores de cefalópodos, lo cual mejorará el conocimiento del papel de los cefalópodos en los ecosistemas marinos en los que se integran

Identificación de las poblaciones de pota saltadora (Ommastrephes bartramii) en el Pacífico Norte a partir de la morfología de estatolitos y mandíbulas

Cephalopods are becoming increasingly important in global fisheries as a result of increased landings and are playing an important ecological role in the trophic dynamics of marine ecosystems. Ommastrephes bartramii is a pelagic cephalopod species with two widely distributed spawning stocks in the North Pacific Ocean. It is also a major fishing target for the Chinese squid jigging fleets. Successful separation of these two spawning stocks is critical to fisheries management, but tends to be challenging because of their similar morphology. In this study we attempted to identify the stocks based on discriminant analyses of 9 morphological variables of statolith and 12 variables of beaks measured for O. bartramii samples in the North Pacific. A significant difference was revealed in the standardized beak and statolith variables between sexes in the northeast (NE) stock (P 0.05), whereas the NW stock showed no significant difference in either sex for the statolith variables (P > 0.05). The same sex also revealed different patterns with different hard structures between the two stocks. In t-tests females showed significant differences between stocks in statolith morphology (P 0.05), but showed no difference between cohorts (P > 0.05) in beak morphometric variables. With the combination of two standardized hard parts, correct classification of stepwise discriminant analysis (SDA) was raised by nearly 20% compared with using only one structure, although overlaps of the NW stock were still found in the scatter-plots. It is concluded that adding more appropriate hard structure variables will effectively increase the success of separating geographic stocks by the SDA method.Los cefalópodos son cada vez más importantes en las pesquerías mundiales como consecuencia de su volumen de capturas, jugando un importante rol en la red trófica de los ecosistemas marinos. Ommastrephes bartramii es una especie de cefalópodo pelágico con dos poblaciones de desove de amplia distribución en el Pacífico Norte. Asímismo, es un importante objetivo de las flotas pesqueras chinas de potera automática. La adecuada identificación de sus dos poblaciones de desove es fundamental para la gestión de esta pesquería, siendo una difícil tarea debido a su morfología similar. En este estudio se pretende identificar los stocks en función de los análisis discriminantes de nueve variables morfológicas del estatolito y doce variables de las mandíbulas, obtenidas en muestras de O. bartramii del Pacífico Norte. Se hallaron diferencias significativas entre sexos en las variables mandíbula y estatolito para el stock del noreste (stock NE) (P 0.05), las medidas del estatolito no mostraron diferencias significativas en ambos sexos para el stock NO (P > 0.05). Para cada sexo, también se hallaron diferencias entre las estructuras duras de ambos stocks. Los tests T-Student mostraron diferencias entre las hembras de ambos stocks en relación a la morfología del estatolito (P 0.05), no observándose diferencias entre las cohortes de machos (P > 0.05) en las variables morfométricas de la mandíbula entre los dos stocks. En comparación con el uso de una sola estructura dura, el estudio conjunto de ambas estructuras mediante análisis discriminante incrementó en cerca de un 20% la correcta asignación a los diferentes stocks, a pesar de algunos solapamientos observados en los diagramas de dispersión del stock NO. Se puede considerar que el empleo adicional de estructuras duras adecuadas aumentará la probabilidad de identificar los stocks mediante análisis discriminante

A modeling approach to identify optimal habitat and suitable fishing grounds for neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean

We developed a habitat suitability index (HSI) model to understand and identify the optimal habitat and potential fishing grounds for neon f lying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean. Remote sensing data, including sea surface temperature, sea surface salinity, sea surface height, and chlorophyll-a concentrations, as well as fishery data from Chinese mainland squid f leets in the main fishing ground (150–165°E longitude) from August to October, from 1999 to 2004, were used. The HSI model was validated by using fishery data from 2005. The arithmetic mean modeling with three of the environmental variables—sea surface temperature, sea surface height anomaly, and chlorophyll- a concentrations—was defined as the most parsimonious HSI model. In 2005, monthly HSI values >0.6 coincided with productive fishing grounds and high fishing effort from August to October. This result implies that the model can reliably predict potential f ishing grounds for O. bartramii. Because spatially explicit fisheries and environmental data are becoming readily available, it is feasible to develop a dynamic, near real-time habitat model for improving the process of identifying potential fishing areas for and optimal habitats of neon flying squid

Fishery biology of the jumbo flying squid <i>Dosidicus gigas</i> off the Exclusive Economic Zone of Chilean waters

The jumbo flying squid Dosidicus gigas is widely distributed in the eastern Pacific Ocean and supports an important fishery. Although many studies have been carried out on the biology of this species, limited biological information is available in the waters outside the Exclusive Economic Zone of Chile (EEZ) (20°S-41°S and 74°30’W-84°W). Three surveys were conducted in this area by the Chinese squid jigging vessels during the period from April 2006 to May 2008. The majority of the catch in the survey was from the two areas defined by 37°30’-41°S and 78°30’-80°W and by 25°-30°S and 76°-77°30’W. The sex ratio (M: F) of the catch was 1: 2.48. The mean mantle length (ML) was 376 mm for males with a range of 257-721 mm and 388.7 mm for females with a range of 236-837 mm. Two distinguished size classes, medium- and large-sized groups, were identified in this study with the medium-sized group (350-450 mm ML) consisting of 89% of the total catch. The sizes at first sexual maturity were 638 mm ML for females and 565 mm ML for males. This study suggests that all the individuals examined were hatched from March 2007 to February 2008, indicating that D. gigas might spawn all year around with a peak spawning time from November 2007 to January 2008. Most of the stomachs analyzed had food remains. The preys included three major groups: fish (mainly lanternfish), cephalopods and crustaceans, but D. gigas was the dominant species in the stomach contents, showing strong evidence of cannibalism. The information obtained from this study improves our understanding of the fishery biology of D. gigas off Chile

World squid fisheries

Peer reviewedPublisher PD

Species identification of <i>Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis</i> and <i>Illex argentinus</i> (Ommastrephidae) using beak morphological variables

Four oceanic squid species, Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis and Illex argentinus, not only support important commercial fisheries, but also play a vital role in their marine ecosystems. It is therefore important to identify them in the analyses of their predators’ stomach contents as this can yield critical information on the trophic dynamics of ecosystems. Hard beaks of the four species frequently found in their predators’ stomachs can be used to identify them. In this study, to remove the effect of size differences among individuals, measurements of upper and lower beaks were standardized with an allometric model. A discriminant analysis was carried out to compare morphological differences among the four species and between the sexes for each species. The upper rostral width and upper rostral length showed the greatest interspecific variation in the beak morphological variables of the four Ommastrephidae. The linear discriminant functions of beak morphological variables were developed for the four Ommastraphidae, which resulted in a rate of correct species classification of over 97%. Sexual dimorphism was also found in the beak morphology of O. bartramii and I. argentinus. This study suggests that morphological variables can be used to reliably classify Ommastrephidae at genus level, which can help identify the specie in the stomachs of cephalopod predators. This helps to improve the understanding of the role cephalopods play in their marine ecosystems

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO