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Ultramicroeletrodo de irídio com filme de mercúrio eletrodepositado para medidas in situ de íons metálicos e pesticidas em solos e águas naturais; Iridium based ultramicroelectrodes with an electro-platted mercury film for in situ determination of metallic ions and pesticides in soil and natural waters

Silva Júnior, Paulo Roberto Vieira da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/06/2009 Português
Relevância na Pesquisa
85.71%
Neste trabalho foram desenvolvidas metodologias para a determinação de substâncias de interesse, como metais pesados (micronutrientes e contaminantes), macronutrientes e pesticidas em solo e águas naturais com ultramicroeletrodo de irídio recoberto com filme de Hg eletrodepositado (UME Ir-Hg) e técnicas voltamétricas, utilizando uma cápsula porosa de cerâmica como cela eletroquímica. As metodologias de medidas com os ultramicroeletrodos foram desenvolvidas inicialmente em condições controladas e posteriormente aplicadas a medidas in-situ, com experimentos com águas naturais e solos, conduzidos em laboratório e também com posteriores medidas em amostras reais. Segundo os resultados obtidos foi possível explorar as metodologias voltamétricas, principalmente as de pulso e redissolução anódica, como ferramentas para estudos in-situ dos metais Cd(II), Pb(II) e Cu(II) e do inseticida organofosforado paration metílico, substâncias de grande interesse, obtendo-se um bom nível de repetibilidade e sensibilidade, com limites de detecção em amostras reais de centenas de ppb's.; In this work a methodology for determination of metallic ions (micronutrients and contaminants), macronutrients and pesticides in soil and natural waters was developed using an Hg plated iridium based ultramicroelectrode and voltammetric techniques...

Desenvolvimento de procedimento analítico para a determinação in situ de glicerol livre em biodiesel; Development of an analytical procedure for in situ determination of free glycerol in biodiesel

Ribeiro, Mauricio Sodré
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/10/2011 Português
Relevância na Pesquisa
65.65%
O biodiesel é um biocombustível proveniente de fontes renováveis, que pode ser obtido a partir da transesterificação de óleos vegetais e/ou gordura animal, produzindo alquil-ésteres de ácidos graxos e um importante resíduo, o glicerol. Este coproduto deve ser removido para a comercialização do biocombustível, pois concentrações altas podem causar danos aos motores de ciclo diesel, além da produção de gases altamente tóxicos durante a combustão. O objetivo deste trabalho foi o desenvolvimento de um procedimento analítico empregando um sistema de fase única para a determinação in situ de glicerol livre em biodiesel. Procedimentos analíticos para análises in situ trazem vantagens, tais como rapidez na resposta ao monitoramento de um processo industrial, evitando trabalhos de reprocessamento, ou no screening de amostras durante fiscalizações em campo, permitindo não só tomadas de decisões imediatas, como também no encaminhamento de apenas amostras duvidosas para análises laboratoriais mais detalhadas. As análises in situ devem ter como principais características a praticidade, rapidez, robustez, uso de reagentes estáveis e pouco tóxicos e possibilidade de emprego de instrumentos portáteis. O procedimento desenvolvido é baseado na oxidação do glicerol por periodato gerando formaldeído...

Análise da influência da condutividade hidráulica saturada dos solos nos escorregamentos rasos na bacia do rio Guaxinduba (SP); Analysis of the influence of saturated hydraulic conductivity from soils in the shallow landslides in the Basin of the River Guaxinduba (SP)

Gomes, Maria Carolina Villaça
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/07/2012 Português
Relevância na Pesquisa
75.75%
A previsão de áreas suscetíveis a escorregamentos translacionais rasos tem como fundamental etapa a investigação dos fatores condicionantes e dos mecanismos de ruptura. Algumas destas propriedades, como os parâmetros físicos e hidrológicos dos solos, são determinantes para a instabilização de encostas que estão sujeitas a eventos pluviométricos intensos. Uma destas propriedades é a condutividade hidráulica saturada, cujo comportamento pode influenciar no desenvolvimento de poro-pressão positiva ou levar à perda de sucção dos solos, ocasionando rupturas. Desta forma, o objetivo principal desta pesquisa foi analisar a distribuição lateral e vertical da condutividade hidráulica saturada (Ksat) dos solos e sua influência nos escorregamentos translacionais rasos na Serra do Mar (SP). Para tanto, foi selecionada uma bacia representativa da Serra do Mar e nela foram escolhidas três cicatrizes acessíveis e com limites bem preservados para a realização dos ensaios in situ. As profundidades onde foram realizados os ensaios foram definidas a partir da caracterização morfológica dos mantos de alteração nas trincheiras abertas no topo, no centro e na lateral das cicatrizes (0.25, 0.50, 1.00, 1.50, 2.00 e 2.50 m). Finamente...

Quantification of the total suspended matter concentration in the sea breaking zone from in situ measurements and remotely sensed data - two empirical approaches

teodoro, ac; marcal, ars; veloso-gomes, f
Fonte: Universidade do Porto Publicador: Universidade do Porto
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
65.69%
Remote sensing techniques can be used to calculate suspended sediment concentrations and to understand the flux and distribution of sediments driven by mechanisms such as tides and waves, river discharges, etc. The main objective of this study is the quantification of the Total Suspended Matter (TSM) concentration in the sea breaking zone for a particular area of the Portuguese coast, around Aveiro. The methodology used was based on in situ measurements and multi spectral satellite images. In situ experimental techniques (maritime platform, aerial platform, simulation on the beach and water sample collection in the breaking zone) were used to determine a relationship between the TSM concentration and the seawater reflectance in the breaking zone. Spectral reflectance was measured with a spectroradiometer and water samples were simultaneously collected. Empirical relationships were established between TSM concentration and the equivalent reflectance values for sensors SPOT/HRVIR, TERRA/ASTER and Landsat/TM at visible and Near Infra Red (NIR) bands computed from the experimental data. Satellite images from ASTER, SPOT HRVIR and Landsat TM were used together with the same empirical models. These satellite images were calibrated and atmospherically corrected. Equations of linear...

In situ measurements of external pH and optical density oscillations in Dictyostelium discoideum aggregates

Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/05/1986 Português
Relevância na Pesquisa
65.69%
In situ measurements of extracellular pH by means of microelectrodes and in situ measurements of optical density were performed on aggregating cells of Dictyostelium discoideum. Early aggregation stage AX2 cells showed sinusoidal pH oscillations, which could be inhibited by the specific relay inhibitor caffeine, indicating that they were coupled to cAMP oscillations. Sometimes biphasic pH oscillations were found, which can be explained by the superposition of two harmonic pH oscillations. These harmonic oscillations might arise by gating of the cAMP signal; a part of the cells respond to every cAMP signal and another subpopulation to every second cAMP pulse. Late aggregation- stage cells showed complex changes of the extracellular pH, which could be inhibited by caffeine. Optical density measurements of wave propagation in aggregation streams of HG220 also revealed gating behavior. In addition to sinusoidal optical density oscillations, biphasic and still more complex oscillations were observed.

Estimation of musculoskeletal models from in situ measurements of muscle action in the rat hindlimb

Yeo, Sang Hoon; Mullens, Christopher H.; Sandercock, Thomas G.; Pai, Dinesh K.; Tresch, Matthew C.
Fonte: Company of Biologists Publicador: Company of Biologists
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
65.72%
Musculoskeletal models are often created by making detailed anatomical measurements of muscle properties. These measurements can then be used to determine the parameters of canonical models of muscle action. We describe here a complementary approach for developing and validating muscle models, using in situ measurements of muscle actions. We characterized the actions of two rat hindlimb muscles: the gracilis posticus (GRp) and the posterior head of biceps femoris (BFp; excluding the anterior head with vertebral origin). The GRp is a relatively simple muscle, with a circumscribed origin and insertion. The BFp is more complex, with an insertion distributed along the tibia. We measured the six-dimensional isometric forces and moments at the ankle evoked from stimulating each muscle at a range of limb configurations. The variation of forces and moments across the workspace provides a succinct characterization of muscle action. We then used this data to create a simple muscle model with a single point insertion and origin. The model parameters were optimized to best explain the observed force–moment data. This model explained the relatively simple muscle, GRp, very well (R2>0.85). Surprisingly, this simple model was also able to explain the action of the BFp...

The Response of Stratospheric Water Vapor to a Changing Climate: Insights from In Situ Water Vapor Measurements

Sargent, Maryann Racine
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
Português
Relevância na Pesquisa
75.73%
Stratospheric water vapor plays an important role in the Earth system, both through its role in stratospheric ozone destruction and as a greenhouse gas contributing to radiative forcing of the climate. Highly accurate water vapor measurements are critical to understanding how stratospheric water vapor concentrations will respond to a changing climate. However, the past disagreement among water vapor instruments on the order of 1 – 2 ppmv hinders understanding of the mechanisms which control stratospheric humidity, and the reliable detection of water vapor trends. In response to these issues, we present a new dual axis water vapor instrument that combines the heritage Harvard Lyman-(alpha) hygrometer with the newly developed Harvard Herriott Hygrometer (HHH). The Lyman-(alpha) instrument utilizes ultraviolet photo-fragment fluorescence detection, and its accuracy has been demonstrated though rigorous laboratory calibrations and in situ diagnostic procedures. HHH employs a tunable diode near-IR laser to measure water vapor via direct absorption in a Herriott cell; it demonstrated in-flight precision of 0.1 ppmv (1-sec) with accuracy of 5%±0.5 ppmv. We describe these two measurement techniques in detail along with our methodology for calibration and details of the measurement uncertainties. We also examine the recent flight comparison of the two instruments with several other in situ hygrometers during the 2011 MACPEX campaign...

In situ stress field of eastern Australia.

Hillis, R.; Reynolds, S.; Enever, J.
Fonte: Taylor and Francis Publicador: Taylor and Francis
Tipo: Artigo de Revista Científica
Publicado em //1999 Português
Relevância na Pesquisa
65.69%
New in situ data based on hydraulic fracturing and overcoring have been compiled for eastern Australia, increasing from 23 to 110 the number of in situ stress analyses available for the area between and including the Bowen and Sydney Basins. The Bowen Basin displays a consistent north-northeast maximum horizontal stress (σH ) orientation over some 500 km. Stress orientations in the Sydney Basin are more variable than in the Bowen Basin, with areas of the Sydney Basin exhibiting north-northeast, northeast, east-west and bimodal σH orientations. Most new data indicate that the overburden stress (σV ) is the minimum principal stress in both the Bowen and Sydney Basins. The Sydney Basin is relatively seismically active, whereas the Bowen Basin is relatively aseismic. Despite the fact that in situ stress measurements sample the stress field at shallower depth than the seismogenic zone, there is a correlation between the stress measurements and seismicity in the two areas. Mohr-Coulomb analysis of the propensity for failure in the Sydney Basin suggests 41% of the new in situ stress data are indicative of failure, as opposed to 13% in the Bowen Basin. The multiple pre-existing structural grains in the Sydney Basin further emphasise the difference between propensity for failure in the two areas. Previous modelling of intraplate stresses due to plate boundary forces has been less successful at predicting stress orientations in eastern than in western and central Australia. Nonetheless...

Quantitative in-situ measurements of sodium release during the combustion of single coal particles using planar laser induced fluorescence.

van Eyk, Philip Joseph
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011 Português
Relevância na Pesquisa
65.71%
The release of sodium from low rank coal during combustion is known to be an important factor in the phenomena of fouling and corrosion in industrial boilers. Although much is known about the gas phase chemistry of sodium compounds, and the likely sequence of events that lead to fouling and corrosion, very little fundamental work has been undertaken on the release of sodium from the coal particle as it is combusted. The principal objective of this study was to perform detailed quantitative measurements and mathematical modelling of sodium release during combustion of single brown coal particles. Planar Laser Induced Fluorescence (PLIF) was applied for the in-situ measurement of the atomic sodium concentration field in the plume of single Loy Yang brown coal particles. Laser absorption measurements at the sodium D1 line (589.59 nm) were utilised to calibrate PLIF measurements of atomic sodium in a purpose designed flat flame environment. Detailed measurements of atomic sodium in the plume of single combusting brown coal particles of varying amounts and forms of sodium and of varying particle sizes were then undertaken. A run-of-mine Loy Yang brown coal sample and two samples that were processed using Mechanical/Thermal Expression (MTE)...

Development and Practical Tests of Insulating/Cooling Capsule with Sensor for in-situ Measurements of CO Concentrations on Moving Grates in MSWI

MARTINEC JIRI; SCHOSGER JEAN-PIERRE; BAXTER DAVID; SVOBODA Karel; MARTINCOVA Jana Victoria
Fonte: Curran Associates Publicador: Curran Associates
Tipo: Contributions to Conferences Formato: Printed
Português
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65.66%
MSW incineration consists of combustion of heterogeneous waste on a moving grate that transports and mixes the waste during the combustion process. The grate combustion process involves drying, devolatilization, gasification/combustion and char burn-out. Also gasification and pyrolysis are subsets of combustion. Mathematical modeling of combustion on the grate requires determining the flow field and concentrations of gaseous species in a reacting and moving bed, taking into account various heat transfer mechanisms. Development of an accurate mathematical model of the incineration process is limited by the lack of measured data for validation. Requirements for specific (in-situ) data essential for the development of an incinerator burning bed model and a better understanding of the grate combustion process prompted accurate measurement of concentrations of selected gases within a moving, burning bed of solid waste. For this purpose a special cube-capsule has been designed and developed with insulating refractory ceramic fibers and materials with cooling effects, enabling measurements of temperature and CO by an electrochemical sensor, small gas pump and internal electronics. This unique self-contained and mechanically/thermally protected probe consisting of measuring and recording electronic components was able to withstand temperatures over 1000°C for a period longer than two hours. The measurement technique differs from all conventional methods. The capsule (casket) can be introduced into the incinerator together with the waste and hence experience the same conditions on the grate as the waste material. This novel device proved to be convenient for in-situ measurements in moving grate incineration.; JRC.F.2-Cleaner energies

Development and Practical Tests of Insulating/cooling Capsule with Sensor for In-situ Measurements of CO Concentrations on Moving Grates in MSWI

MARTINEC Jiri; SKÁLA Z; SCHOSGER JEAN-PIERRE; BAXTER DAVID
Fonte: Czech Society of Chemical Engineers Publicador: Czech Society of Chemical Engineers
Tipo: Contributions to Conferences Formato: Printed
Português
Relevância na Pesquisa
65.68%
The disposal of waste (particularly of municipal solid waste) that cannot be minimized, recycled or reused presents a huge international problem. The last 20 years is characterized by a gradual transition from landfilling of the municipal solid waste (MSW) to incineration. The incineration of MSW under existing legislation and operational boundary conditions is a very complex process with the application of two-stage combustion, minimization of emissions and production of energy (generally heat and electricity). In MSW incinerators, the first stage consists of combustion of heterogeneous waste on a moving grate that transports and mixes the waste during the combustion process. The grate combustion process involves drying, devolatilization, gasification/combustion and char burn-out. Thus, gasification and pyrolysis are subsets of the combustion problem. Mathematical modeling of combustion on the grate requires the solution of the flow field and concentrations of gaseous species in a reacting and moving bed, taking into account various heat transfer mechanisms. Development of an accurate mathematical model of the incineration process is limited by the lack of measured data for validation. Requirements for specific (in-situ) data essential for the development of an incinerator burning bed model and a better understanding of the grate combustion process prompted accurate measurement of concentrations of selected gases within a moving...

A Space weather information service based upon remote and in-situ measurements of coronal mass ejections heading for Earth: A concept mission consisting of six spacecraft in a heliocentric orbit at 0.72 AU

Ritter, Birgit; Meskers, Arjan J. H.; Miles, Oscar; Ru??wurm, Michael; Scully, Stephen; Rold??n Aranda, Andr??s; Hartkorn, Oliver; J??stel, Peter; R??ville, Victor; Lupu, Sorina; Ruffenach, Alexis
Fonte: EDP Sciences Publicador: EDP Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
85.71%
The Earth???s magnetosphere is formed as a consequence of interaction between the planet???s magnetic field and the solar wind, a continuous plasma stream from the Sun. A number of different solar wind phenomena have been studied over the past 40 years with the intention of understanding and forecasting solar behavior. One of these phenomena in particular, Earth-bound interplanetary coronal mass ejections (CMEs), can significantly disturb the Earth???s magnetosphere for a short time and cause geomagnetic storms. This publication presents a mission concept consisting of six spacecraft that are equally spaced in a heliocentric orbit at 0.72 AU. These spacecraft will monitor the plasma properties, the magnetic field???s orientation and magnitude, and the 3D-propagation trajectory of CMEs heading for Earth. The primary objective of this mission is to increase space weather forecasting time by means of a near real-time information service, that is based upon in-situ and remote measurements of the aforementioned CME properties. The obtained data can additionally be used for updating scientific models. This update is the mission???s secondary objective. In-situ measurements are performed using a Solar Wind Analyzer instrumentation package and fluxgate magnetometers...

In-situ studies of protein-resistant self-assembling monolayers; In-situ Studien von proteinresistenten selbst-assemblierenden Monolagen

Zorn, Stefan
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertation; info:eu-repo/semantics/doctoralThesis
Português
Relevância na Pesquisa
75.82%
The aim of this work was the in-situ characterization of hexa(ethylene glycol) self-assembling monolayers (SAMs), their growth in water, their structural changes at elevated temperatures and their longtime stability. The focus was on the interaction of the thiol molecules with the surrounding water molecules and the conformational and structural consequences. The importance of the utilization of surfaces functionalized with SAMs has increased enormously over the last years. Their spontaneous organization into well ordered crystalline structures allows systematical changes of the chemical properties of surfaces and therefore an enormous bandwidth of applications. In the center of this work are SAMs, which are able to passivate surfaces against unspecific protein absorption. They can be used e.g. in medical applications to hinder the irreversible adsorption of proteins with surfaces, to structure cells on surfaces or in combination with specific headgroups as sensor elements. A key to the understanding of the mechanism of protein resistance is the ability of the SAM to bind water molecules at their surface and in their interior. Infrared spectroscopy is a well suited technique for the identification of molecules and their structural changes due to the interaction with their environment. Due to the strong absorption of water in the fingerprint region it is challenging to measure molecules in aqueous environment (in-situ). This problem can be overcome by the surface sensitive polarization modulation infrared reflection absorption spectroscopy (PMIRRAS) technique in combination with a thin liquid layer cell allowing to perform in-situ measurements with a very high signal-to-noise ratio. Since such in-situ measurements are much more challenging as measurements in air...

Accurate Measurements of Pointing Performance from In Situ Observations

Gajos, Krzysztof Z; Reinecke, Katharina; Herrmann, Charles
Fonte: Association for Computing Machinery Publicador: Association for Computing Machinery
Tipo: Conference Paper
Português
Relevância na Pesquisa
65.68%
We present a method for obtaining lab-quality measurements of pointing performance from unobtrusive observations of natural in situ interactions. Specifically, we have developed a set of user-independent classifiers for discriminating between deliberate, targeted mouse pointer movements and those movements that were affected by any extraneous factors. To develop and validate these classifiers, we developed logging software to unobtrusively record pointer trajectories as participants naturally interacted with their computers over the course of several weeks. Each participant also performed a set of pointing tasks in a formal study set-up. For each movement, we computed a set of measures capturing nuances of the trajectory and the speed, acceleration, and jerk profiles. Treating the observations from the formal study as positive examples of deliberate, targeted movements and the in situ observations as unlabeled data with an unknown mix of deliberate and distracted interactions, we used a recent advance in machine learning to develop the classifiers. Our results show that, on four distinct metrics, the data collected in-situ and filtered with our classifiers closely matches the results obtained from the formal experiment.; Engineering and Applied Sciences

Report on Instrumentation and Methods for In-Situ Measurements of the Secondary Electron Yield in an Accelerator Environment

Hartung, W. H.; Asner, D. M.; Conway, J. V.; Dennett, C. A.; Greenwald, S.; Kim, J. -S.; Li, Y.; Moore, T. P.; Omanovic, V.; Palmer, M. A.; Strohman, C. R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
65.73%
The achievable beam current and beam quality of a particle accelerator can be limited by the build-up of an electron cloud (EC) in the vacuum chamber. Secondary electron emission from the walls of the vacuum chamber can contribute to the growth of the electron cloud. An apparatus for in-situ measurements of the secondary electron yield (SEY) of samples in the vacuum chamber of the Cornell Electron Storage Ring (CESR) has been developed in connection with EC studies for the CESR Test Accelerator program (CesrTA). The CesrTA in-situ system, in operation since 2010, allows for SEY measurements as a function of incident electron energy and angle on samples that are exposed to the accelerator environment, typically 5.3 GeV counter-rotating beams of electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY with discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. The SEY chambers can be isolated from the CESR beam pipe, allowing us to exchange samples without venting the CESR vacuum chamber. Measurements so far have been on metal surfaces and EC-mitigation coatings. The goal of the SEY measurement program is to improve predictive models for EC build-up and EC-induced beam effects. This report describes the CesrTA in-situ SEY apparatus...

In-Situ Measurements of the Secondary Electron Yield in an Accelerator Environment: Instrumentation and Methods

Hartung, W. H.; Asner, D. M.; Conway, J. V.; Dennett, C. A.; Greenwald, S.; Kim, J. -S.; Li, Y.; Moore, T. P.; Omanovic, V.; Palmer, M. A.; Strohman, C. R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/12/2014 Português
Relevância na Pesquisa
65.73%
The performance of a particle accelerator can be limited by the build-up of an electron cloud (EC) in the vacuum chamber. Secondary electron emission from the chamber walls can contribute to EC growth. An apparatus for in-situ measurements of the secondary electron yield (SEY) in the Cornell Electron Storage Ring (CESR) was developed in connection with EC studies for the CESR Test Accelerator program. The CESR in-situ system, in operation since 2010, allows for SEY measurements as a function of incident electron energy and angle on samples that are exposed to the accelerator environment, typically 5.3 GeV counter-rotating beams of electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY with discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. The samples can be exchanged without venting the CESR vacuum chamber. Measurements have been done on metal surfaces and EC-mitigation coatings. The in-situ SEY apparatus and improvements to the measurement tools and techniques are described.; Comment: 16 pages, 18 figures; this paper is a condensed version of arXiv:1407.0772

A Space Weather Information Service Based Upon Remote and In-Situ Measurements of Coronal Mass Ejections Heading for Earth

Ritter, Birgit; Meskers, Arjan J. H.; Miles, Oscar; Rußwurm, Michael; Scully, Stephen; Roldán, Andrés; Hartkorn, Oliver; Jüstel, Peter; Réville, Victor; Lupu, Sorina; Ruffenach, Alexis
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/02/2015 Português
Relevância na Pesquisa
65.69%
The Earth's magnetosphere is formed as a consequence of interaction between the planet's magnetic field and the solar wind, a continuous plasma stream from the Sun. A number of different solar wind phenomena have been studied over the past forty years with the intention of understanding and forecasting solar behavior. One of these phenomena in particular, Earth-bound interplanetary coronal mass ejections (CMEs), can significantly disturb the Earth's magnetosphere for a short time and cause geomagnetic storms. This publication presents a mission concept consisting of six spacecraft that are equally spaced in a heliocentric orbit at 0.72 AU. These spacecraft will monitor the plasma properties, the magnetic field's orientation and magnitude, and the 3D-propagation trajectory of CMEs heading for Earth. The primary objective of this mission is to increase space weather (SW) forecasting time by means of a near real-time information service, that is based upon in-situ and remote measurements of the aforementioned CME properties. The mission's secondary objective is to provide vital data to update scientific models. In-situ measurements are performed using a Solar Wind Analyzer instrumentation package and flux gate magnetometers, while coronagraphs execute remote measurements. Communication with the six identical spacecraft is realized via a deep space network consisting of six ground stations. They provide an information service that is in uninterrupted contact with the spacecraft...

Contemporary interstellar meteoroids in the solar system - in situ measurements and clues on composition

Landgraf, M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/09/2001 Português
Relevância na Pesquisa
65.75%
Meteoroids originating from the local interstellar medium, traverse the solar system. This has been proven by in situ measurements by interplanetary spacecraft as well as highly sensitive radar measurements. Early attempts to detect interstellar meteoroids using the instruments on board the Pioneer 8 and 9 spacecraft failed. More sensitive detectors on board the joint ESA/NASA mission Ulysses as well as on board the NASA spacecraft Galileo, however, unambiguously detected meteoroids of interstellar origin. This discovery has started efforts to compare the results from the in situ measurements with highly sophisticated models of interstellar dust properties derived from astronomical absorption and extinction measurements. It was found that, at least locally, is more mass locked up in meteoroids than expected from the astronomical measurements. So far the in situ measurements only allow to derive composition information indirectly via the meteoroid's dynamics.; Comment: 6 pages, 7 figures, 2 tables, to appear in the proceedings of the Meteoroids 2001 conference in Kiruna, Sweden, 6-10 August 2001

The Deflection of the Two Interacting Coronal Mass Ejections of 2010 May 23-24 as Revealed by Combined In situ Measurements and Heliospheric Imaging

Lugaz, N.; Farrugia, C. J.; Davies, J. A.; Möstl, C.; Davis, C. J.; Roussev, I. I.; Temmer, M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 11/09/2012 Português
Relevância na Pesquisa
65.76%
In 2010 May 23-24, SDO observed the launch of two successive coronal mass ejections (CMEs), which were subsequently tracked by the SECCHI suite onboard STEREO. Using the COR2 coronagraphs and the heliospheric imagers (HIs), the initial direction of both CMEs is determined to be slightly west of the Sun-Earth line. We derive the CME kinematics, including the evolution of the CME expansion until 0.4 AU. We find that, during the interaction, the second CME decelerates from a speed above 500 km/s to 380 km/s the speed of the leading edge of the first CME. STEREO observes a complex structure composed of two different bright tracks in HI2-A but only one bright track in HI2-B. In situ measurements from Wind show an "isolated" ICME, with the geometry of a flux rope preceded by a shock. Measurements in the sheath are consistent with draping around the transient. By combining remote-sensing and in situ measurements, we determine that this event shows a clear instance of deflection of two CMEs after their collision, and we estimate the deflection of the first CME to be about 10 degrees towards the Sun-Earth line. The arrival time, arrival speed and radius at Earth of the first CME are best predicted from remote-sensing observations taken before the collision of the CMEs. Due to the over-expansion of the CME after the collision...

Using a Complex-Impedance Measuring Instrument to Determine In Situ Soil Unit Weight and Moisture Content

Meehan, Christopher L.; Hertz, Jason S.
Fonte: ASTM International Publicador: ASTM International
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
75.74%
Author's final manuscript; In situ measurements of soil unit weight and moisture content play a critical role in conventional compaction quality assurance and quality control procedures. Recently, there have been a number of attempts to develop alternative electrically-based test devices that can be used to measure the in situ unit weight and/or moisture content of a compacted soil; these devices are intended to serve as alternatives to more traditional tests such as sand cone, rubber balloon, drive cylinder, or nuclear density gauge tests. The study described in this paper focuses on the use of a relatively new electrically-based in situ soil test device that uses measurements of soil complex impedance, soil capacitance, and soil resistance to infer in situ soil unit weight and moisture content; this device is typically referred to as a complex-impedance measuring instrument (CIMI). This paper provides a detailed explanation of current CIMI operating principles and also describes the utilization of a CIMI for field- and laboratory-based testing. The CIMI used in this study was calibrated and assessed in two field compaction projects in which different silty sands were used for construction. A mold-based calibration approach was developed for building an electrically-based soil model using the CIMI; this approach provides an alternative to field calibration of the device. In order to perform a more complete assessment of the CIMI in a controlled environment...