957 resultados para peak height velocity
Resumo:
Cold-water corals, such as Lophelia pertusa, are key habitat-forming organisms found throughout the world's oceans to 3000 m deep. The complex three-dimensional framework made by these vulnerable marine ecosystems support high biodiversity and commercially important species. Given their importance, a key question is how both the living and the dead framework will fare under projected climate change. Here, we demonstrate that over 12 months L. pertusa can physiologically acclimate to increased CO2, showing sustained net calcification. However, their new skeletal structure changes and exhibits decreased crystallographic and molecular-scale bonding organization. Although physiological acclimatization was evident, we also demonstrate that there is a negative correlation between increasing CO2 levels and breaking strength of exposed framework (approx. 20-30% weaker after 12 months), meaning the exposed bases of reefs will be less effective 'load-bearers', and will become more susceptible to bioerosion and mechanical damage by 2100.
Resumo:
Characteristics of the impacts su!ered by the fruit on a transfer point of an experimental fruit packing line were analysed. The transfer is made up by two transporting belts at di!erent heights forming an angle of 903. These transfer points are very common in fruit packing lines, in which fruits receive two impacts: the "rst onto the belt base and the second into the lateral plate. Diferent tests were carried out to study the e!ect of transfer height, velocity, belt structure and padding on the acceleration values recorded by an instrumental sphere (IS 100). Results showed that transfer height and belt structure a!ect mainly impact values on the belt base, and padding a!ects mainly impact values registered for lateral contact. The elect of belt velocity in both impacts is less important when compared to the rest of the variables. Additionally, two powered transfer decelerators were tested at the same point with the aim of decreasing impacts su!ered by the fruit. Comparing impacts registered using these decelerators to those analysed in the first part of the study without decelerators, a high reduction of the impact values was observed.
Resumo:
El presente proyecto de fin de carrera describe y analiza el estudio integral del efecto de las vibraciones producidas por voladuras superficiales realizadas en el proyecto del “Tercer Juego de Esclusas” ejecutado para la Expansión del Canal de Panamá. Se recopilan un total de 53 registros, data generada por el monitoreo de 7 sismógrafos en 10 voladuras de producción realizadas en el año 2010. El fenómeno vibratorio tiene dos parámetros fundamentales, la velocidad pico-partícula (PPV) y la frecuencia dominante, los cuales caracterizan cuan dañino puede ser éste frente a su influencia sobre las estructuras civiles; por ello, se pretende caracterizarlas y fundamentalmente predecirlas, lo que permitirá su debido control. En función a lo expuesto, el estudio realizado consta de dos partes, la primera describe el comportamiento del terreno mediante la estimación de la ley de atenuación de la velocidad pico-partícula a través del uso de la regresión lineal por mínimos cuadrados; la segunda detalla un procedimiento validable para la predicción de la frecuencia dominante y del pseudo-espectro de respuesta de velocidad (PVRS) basada en la teoría de Newmark & Hall. Se ha obtenido: (i) la ley de atenuación del terreno para distintos grados de fiabilidad, (ii) herramientas de diseño de voladuras basadas en la relación de carga – distancia, (iii) la demostración que los valores de PPV se ajustan a una distribución log-normal, (iv) el mapa de isolíneas de PPV para el área de estudio, (v) una técnica detallada y válida para la predicción de la frecuencia dominante y del espectro de respuesta, (vi) formulaciones matemáticas de los factores de amplificación para el desplazamiento, velocidad y aceleración, (vii) mapa de isolíneas de amplificación para el área de estudio. A partir de los resultados obtenidos se proporciona información útil para su uso en el diseño y control de las voladuras posteriores del proyecto. ABSTRACT This project work describes and analyzes the comprehensive study of the effect of the vibrations produced by surface blasting carried out in the "Third Set of Locks" project executed for the expansion of the Panama Canal. A total of 53 records were collected, with the data generated by the monitoring of 7 seismographs in 10 production blasts carried out in 2010. The vibratory phenomenon has two fundamental parameters, the peak-particle velocity (PPV) and the dominant frequency, which characterize how damaging this can be compared to their influence on structures, which is why this is intended to characterize and predict fundamentally, that which allows proper control. Based on the above, the study consists of two parts; the first describes the behavior of the terrain by estimating the attenuation law for peak-particle velocity by using the ordinary least squares regression analysis, the second details a validable procedure for the prediction of the dominant frequency and pseudo-velocity response spectrum (PVRS) based on the theory of Newmark & Hall. The following have been obtained: (i) the attenuation law of the terrain for different degrees of reliability, (ii) blast design tools based on charge-distance ratio, (iii) the demonstration that the values of PPV conform to a log-normal distribution, (iv) the map of isolines of PPV for the area of study (v) detailed and valid technique for predicting the dominant frequency response spectrum, (vi) mathematical formulations of the amplification factors for displacement, velocity and acceleration, (vii) amplification of isolines map for the study area. From the results obtained, the study provides useful information for use in the design and control of blasting for subsequent projects.
Resumo:
Characteristics of the impacts suffered by the fruit on a transfer point of an experimental fruit packing line were analysed. The transfer is made up by two transporting belts at different heights forming an angle of 90°. These transfer points are very common in fruit packing lines, in which fruits receive two impacts: the first onto the belt base and the second into the lateral plate. Different tests were earned out to study the effect of transfer height, velocity, belt structure and padding on tire acceleration values recorded by an instrumental sphere (IS 100). Results showed that transfer height and belt structure affect mainly impact values on the belt base, and padding affects mainly impact values registered in lateral impact. The effect of belt velocity in both impacts is less important when compared to the rest of the variables. Additionally, two powered transfer decelerators were tested at the same point with the aim of decreasing impacts suffered by the fruit. Comparing impacts registered using these decelerators to those analysed in the first part of the study without decelerators a high reduction of the impact values was observed.
Resumo:
Characterization of a 90° Transfer Point in a Fruit Packing Line. Characteristics of the impacts suffered by the fruit on a transfer point of an experimental fruit packing line were analysed. The transfer is made up by two transporting belts at different heights forming an angle of 90°. Different tests were carried out to study the effect of transfer height, velocity, belt structure and padding on the acceleration values recorded by an instrumental sphere (IS 100). Results showed that transfer height and belt structure affect mainly impact values on the belt base, and padding affects mainly impact values registered in lateral impact. Two powered transfer decelerators were tested at the same point with the aim of decreasing impacts suffered by the fruit.
Resumo:
Este proyecto tiene por objeto el análisis de las diferentes frecuencias y tipos de onda presentes en los registros de vibraciones de las voladuras. Se han utilizado 108 registros de 4 barrenos sencillos disparados individualmente y una voladura de producción. Se estudian así mismo la evolución de las frecuencias (en relación a la distancia y a la geología particular de cresta y plaza) y la ley de atenuación del terreno que relaciona la evolución velocidad de partícula en función de la distancia escalada. Para la voladura de producción se analiza si las vibraciones cumplen la normativa vigente según la norma UNE 22.381.93 “Control de Vibraciones Producidas por Voladuras”. Abstract The main objective of this project is to analyze the different types and frequencies of seismic waves found in blasting logs. 108 logs from 4 single shots and a standard production blasting have been used. The evolution of frequencies (regarding distance and different geologies of crest and toe) and the attenuation law which allows us to obtain peak particle velocity regarding distance are also studied. For the production blasting, data is compared to the limits set by current regulations following the standard UNE 22.381.93 “Control de Vibraciones Producidas por Voladuras”.
Resumo:
We review the mechanical origin of auditory-nerve excitation, focusing on comparisons of the magnitudes and phases of basilar-membrane (BM) vibrations and auditory-nerve fiber responses to tones at a basal site of the chinchilla cochlea with characteristic frequency ≈ 9 kHz located 3.5 mm from the oval window. At this location, characteristic frequency thresholds of fibers with high spontaneous activity correspond to magnitudes of BM displacement or velocity in the order of 1 nm or 50 μm/s. Over a wide range of stimulus frequencies, neural thresholds are not determined solely by BM displacement but rather by a function of both displacement and velocity. Near-threshold, auditory-nerve responses to low-frequency tones are synchronous with peak BM velocity toward scala tympani but at 80–90 dB sound pressure level (in decibels relative to 20 microPascals) and at 100–110 dB sound pressure level responses undergo two large phase shifts approaching 180°. These drastic phase changes have no counterparts in BM vibrations. Thus, although at threshold levels the encoding of BM vibrations into spike trains appears to involve only relatively minor signal transformations, the polarity of auditory-nerve responses does not conform with traditional views of how BM vibrations are transmitted to the inner hair cells. The response polarity at threshold levels, as well as the intensity-dependent phase changes, apparently reflect micromechanical interactions between the organ of Corti, the tectorial membrane and the subtectorial fluid, and/or electrical and synaptic processes at the inner hair cells.
Resumo:
Inspired by recent reports concerning the utilisation of hand drawn pencil macroelectrodes (PDEs), we report the fabrication, characterisation (physicochemical and electrochemical) and implementation (electrochemical sensing) of various PDEs drawn upon a flexible polyester substrate. Electrochemical characterisation reveals that there are no quantifiable electrochemical responses upon utilising these PDEs with an electroactive analyte that requires an electrochemical oxidation step first, therefore the PDEs have been examined towards the electroactive redox probes hexaammineruthenium(III) chloride, potassium ferricyanide and ammonium iron(II) sulfate. For the first time, characterisation of the number of drawn pencil layers and the grade of pencil are examined; these parameters are commonly overlooked when utilising PDEs. It is demonstrated that a PDE drawn ten times with a 6B pencil presented the most advantageous electrochemical platform, in terms of electrochemical reversibility and peak height/analytical signal. In consideration of the aforementioned limitation, analytes requiring an electrochemical reduction as the first process were solely analysed. We demonstrate the beneficial electroanalytical capabilities of these PDEs towards p-benzoquinone and the simultaneous detection of heavy metals, namely lead(II) and cadmium(II), all of which are explored for the first time utilising PDEs. Initially, the detection limits of this system were higher than desired for electroanalytical platforms, however upon implementation of the PDEs in a back-to-back configuration (in which two PDEs are placed back-to-back sharing a single connection to the potentiostat), the detection limits for lead(II) and cadmium(II) correspond to 10 μg L−1 and 98 μg L−1 respectively within model aqueous (0.1 M HCl) solutions.
Resumo:
Investigation of the Middle Miocene-Pleistocene succession in cores at ODP Site 817A (Leg 133), drilled on the slope south of the Queensland Plateau, identified the various material fluxes contributing to sedimentation and has determined thereby the paleogeographic events which occurred close to the studied area and influenced these fluxes. To determine proportions of platform origin and of plankton origin of carbonate mud, two reference sediments were collected: (1) back-reef carbonate mud from the Young Reef area (Great Barrier Reef); and (2) Late Miocene chalk from the Loyalty Basin, off New Caledonia. Through their biofacies and mineralogical and geochemical characters, these reference sediments were used to distinguish the proportions of platform and basin components in carbonate muds of 25 core samples from Hole 817A. Two "origin indexes" (i1 and i2) relate the proportion in platform and basin materials. The relative sedimentation rate is inferred from the high-frequency cycles determined by redox intervals in the cores. Bulk carbonate deposited in each core has been calculated in two ways with close results: (1) from calcimetric data available in the Leg 133 preliminary reports (Davies et al., 1991); and (2) from average magnetic susceptibility of cores, a value negatively correlated to the average carbonate content. Vertical changes in sedimentation rates, in carbonate content, in origin indexes and in "linear fluxes" document the evolution of sediment origins from platform carbonates, planktonic carbonates and insoluble material through time. These data are augmented with the variations in organic-matter content through the 817A succession. The observed changes and their interpretation are not modified by compaction, and are compatible with major paleogeographic events including drowning of the Queensland Plateau (Middle Miocene-Early Pliocene) and the renewal of shallow carbonate production, (1) during the Late Pliocene, and (2) from the Early Pleistocene. The birth and growth of the Great Barrier Reef is also recorded from 0.5 Ma by a strengthening of detrital carbonate deposition and possibly by a lack of clay minerals in the 4 upper cores, a response to trapping of terrigenous material behind this barrier. In addition, a maximum of biological silica production is displayed in the Middle Miocene. These changes constrain the time of events and the sequence-stratigraphy framework some components of which are transgression surface, maximum flooding surface and low-stand turbidites. Sedimentation rates and material fluxes show cycles lasting 1.75 Myr. Whatever their origin (climatic and/or eustatic) these cycles affected the planktonic production primarily. The changes also show that major carbonate variations in the deposits are due to a dilution effect by insoluble material (clay, biogenic silica and volcanic glasses) and that plankton productivity, controlling the major fraction of carbonate sedimentation, depends principally on terrigenous supplies, but also on deep-water upwelling. Accuracy of the method is reduced by redeposition, reworking, and probable occurrence of hiatuses.
Resumo:
Downhole bulk-sample and clay-mineral analytical results for Sites 558 and 563 are presented in this chapter. These results show a Tertiary climatic and hydrologic evolution similar to that at other DSDP drill sites in the northeastern Atlantic Ocean (Sites 398, 403-406, 548-550, 552-555). The sediments recovered at both sites are primarily calcareous and chalky oozes characterized by >90% carbonate and minor quartz and plagioclase feldspar. Clay minerals smectite, kaolinite, illite, and chlorite are present throughout the cores; upsection, illite increases at the expense of smectite. The clay mineralogy suggests climatic cooling and increased ocean circulation during the Miocene. Intervals rich in very fine grained (<2 µm) quartz suggest times of increased eolian input. This could have resulted from development, during Oligocene and late Miocene time, of an arid, desertlike sediment provenance that lasted until the present day.
Resumo:
Thesis (Master's)--University of Washington, 2016-06