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  • ASFA_2015::G::Geomorphology  (10)
  • Polymer and Materials Science  (7)
  • Ecology  (5)
  • 1
    Publication Date: 2021-05-19
    Description: Se presentan los resultados del análisis del comportamiento de las playas en el sector comprendido entre Barranquilla (Bocas de Ceniza) y la Flecha de Galerazarnba. Se levantaron 24 perfiles perpendiculares ala línea de costa durante los dos períodos climáticos característicos (seco y húmedo). En época seca, bajo la influencia de los vientos alisios, las playas pierden su berma y experimentan un retroceso significativo de su frente, en algunos casos del orden de decenas de metros exhibiendo un perfil cóncavo. En la época húmeda, cuando los vientos se debilitan, las playas se reconstruyen y exhiben en su morfología un perfil convexo. Entre Bocas de Ceniza y Santa Verónica las pendientes son suaves y están asociadas a sedimentos finos, mientras que en el sector sur aumenta el gradiente y el tamaño de grano en el frente de playa.
    Description: The results of analysis about the behavior of the beaches in the sector between Barranquilla (Bocas de Ceniza) and flecha de Galerazamba are presented. Twentyfour profiles perpendicular to the coastline were taken between both seasonal períods (dry and humid). On the chy period, under the influence of the westerlies, the beaches lose their berm and experience a significant retrogression on their foreshore, sometimes in the order of tens of meters, exhibiting a concave profile. On the humid season, when the easterlies weaken, the beaches bulld up and exhibit a convex profile in their morphology. Between Bocas de Ceniza and Santa Verónica the slof and are soft and are associated with fine sediment, while on the southern sector the gradient and the size of the grain increase on the foreshore.
    Description: Published
    Keywords: Nivel del mar. ; Vientos ; Oleaje ; Erosión ; Sedimentos ; ASFA_2015::G::Geodynamics ; ASFA_2015::G::Geomorphology ; ASFA_2015::M::Meteorology
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: pp.23-38
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  • 2
    Publication Date: 2021-05-19
    Description: Los procesos costeros de diferente intensidad producen efectos sobre la línea de costa de cualquier región que de una u otra forma afectan su economía. El balance erosión-sedimentación de las playas se encuentra íntimamente ligado a la hidrodinámica del mar y a su interacción con la atmósfera, complementando de esta forma el sistema costa-mar-aire. En el presente documento se relacionan los principales resultados contenidos en el estudio de las características hidrodinámicas y geológicas del Golfo de Urabá, llevado a cabo entre 1988 y 1989 en cooperación con la Misión Técnica Francesa. Este estudio ha permitido identificar la formación de prismas de acrecimiento sedimentario principalmente en los alrededores de los deltas de los ríos Atrato y Turbo, así como definir las condiciones oceanográficas durante las épocas húmeda y media, además de determinar las características morfológicas del lecho marino.
    Description: The coastal process of different intensity are responsible of effects over the coast line in a region which in a way or another affect their economy. The erosion-deposition balance in the beaches is close related to the hidrodinamics of the sea and the interaction with the atmosphere, completing in this way the sistem coast-sea-air. Is this document a relatioship between the main results obtained in the study of the hidrodinamic and geological characteristics of the Gulf of Urabá is presented, carried out between 1988 and 1989 with the cooperation of the French Technical Mission. This study permited to identify the formation of sedimentary accresion prism mainly in the surroundings of the deltas of the Atrato and Turbo rivers, as to define the oceanographical conditions during the humid and dry seasons, and also determine the morphological characteristics of the marine bottom.
    Description: Published
    Keywords: Temperatura ; Salinidad ; Corriente oceánica ; Río Atrato ; ASFA_2015::G::Geomorphology ; ASFA_2015::G::Geodynamics ; ASFA_2015::H::Hydrology
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: Pp.79-90
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  • 3
    Publication Date: 2021-05-19
    Description: En este informe se presentan los resultados obtenidos a partir de un estudio meteorológico, oceanográfico y sedimentológico del golfo de Morrosquillo durante la época seca (feb/93), cuando la velocidad y dirección del viento actuaron como factores determinantes en la circulación de las aguas, la cual se definió a partir de los siguientes parámetros: Distribución de los campos halinos y térmicos, tránsito de los sedimentos depositados sobre la superficie del lecho marino, repartición horizontal y vertical de la turbidez, determinada con base en muestras de campo y calibración y análisis de una imagen de satélite SPOT. El análisis morfológico efectuado mediante la comparación del trazado de la línea de costa sobre imágenes de satélite y fotografías aéreas a diferentes años, permitió establecer las principales variaciones morfológicas en esta zona. Por efecto de difracción y refracción del oleaje frente a Punta San Bernardo y de compensación al llegar a la fecha de Mestizos, el flujo originado por estos vientos produce dos direcciones principales de corrientes: Una en sentido sureste a partir de la Punta San Bernardo, que se desplaza por la costa este del Golfo y la otra en dirección este, bordeando la costa sur y sureste. Los principales cambios morfológicos de la línea de costa se presentaron en el sector sur del Golfo. Como resultado de los procesos de acrecimiento sedimentario se originó a partir de 1938 el delta del Río Sinú al desembocar por la zona de Tinajoes, el cual actualmente continúa su evolución. Los fenómenos erosivos han afectado considerablemente el cuerpo de la flecha de Mestizos, la terraza marina al este de la espiga y el sector de playas entre Coveñas y Tolú.
    Description: This report presents the results from a meteorological and sedimentological study, of the gulf of Morrosquillo during the dry, season (February/93), where the speed and direction of the wind acted as determinant factors in the circulation of the waters, which was defined from the following parameters: Distribution of the (haline) and thermal fields, transit of the sediment deposited on the surface of the marine botton, horizontal and vertical repartition of turbidity, determined on samples and gauging and analysis of a SPOT satellite image. The morphologic analysis through the comparison of the coastal line images and aereal photographies from differents years, allowedto establish the principal coastal morphologic variations in these zones. The effect of difraction and refraction of the surf front the punta San Bernardo and the compensation arriving to the Mestizos arrow, and the flow originated by the winds produces two principal currents: One in direction south-east starting from punta San Bernardo, that is displaced toward the east of the Gulf and the other east skirting the coast south and south-east. The principal morphological changes of the coastal line were introduced in the south sector of the Gulf. As result of the process of sedimentary acretion originated starting 1938 the delta of the Sinú river as its discharge in the Tinajones zone, evolution that continues. The erosive phenomen on has affected considerably the body of the Mestizos arrow, the marine terrace east of the spike and the sector of beaches between Coveñas and Tolú.
    Description: Published
    Keywords: Costa ; Erosión. ; Río. ; ASFA_2015::G::Geomorphology ; ASFA_2015::P::Physical oceanography ; ASFA_2015::M::Meteorology
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: Pp.93-113
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  • 4
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To improve the knowledge of emulsion copolymerization of monomers both swelling their copolymers, but which are of quite different polarity (water solubility), a series of styrene (S)/methyl acrylate (MeA) copolymerizations was carried out in batch at 50°C with potassium persulfate as initiator. The overall rates of copolymerization increase with the amount of MeA in the monomer feed. Copolymer composition follows the usual copolymerization equation if bulk/solution reactivity ratios (rij) and monomer partition between aqueous and organic phase are taken into account (simulation). However, accurate kinetic data at low conversion (gas chromatography) put in evidence an enhanced polymerization of the more hydrophilic monomer (MeA), which can be attributed to polymerization in the water phase. Particle sizes increase with conversion and tend to a limiting value, the higher the MeA content is. Particle number (Np), which is practically constant with conversion of S homopolymerization, tends to increase with MeA content as polymerization proceeds. This trend is enhanced if the emulsifier (sodium dodecanesulfonate, SDS) concentration is increased. Overall propagation rate constants were estimated as function of the experimental conditions and monomer concentration within the particles. From kinetic data (rate of polymerization) and Np, it was found that the average number of radicals per particle, ñ, remains close to 0,5. It was then possible considering S(kp = 125 1 · mol-1 · s-1) as a standard monomer, to estimate the polymerization rate constant for MeA (335 1 · mol-1 · s-1). Since adsorption of emulsifier was shown to be closely related to particle surface composition, the specific area As of SDS was measured on latices at various conversions and initial monomer feeds. As conversions increases, the particle surface appears to be richer and richer in MeA, which corresponds to a particle structuration. Strong and weak acid group titration is also in quite good agreement with the colloidal behaviour.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of emulsion copolymerizations of styrene (S) with methyl acrylate (MeA) initiated by the redox system potassium persulfate (KPS)/sodium hydrogen disulfite (SBS) was carried out at 50°C. The monomer feed composition and the monomer/water (M/W) ratios were widely varied. The polymerization rate was found to be higher than in the case when only KPS was applied. Initial (influence of polymerization in water phase) and final copolymer molecules (accumulation of MeA in the feed due to a lower reactivity) are richer in the more hydrophilic monomer (MeA). It could be shown that a high water solubility makes the emulsion reactivity ratios to be “apparent” kinetic parameters, which result in a higher number of azeotropic compositions, compared to bulk or solution, according to the M/W ratio. Particle sizes are smaller and the size distribution is larger than in polymerizations in the presence of KPS alone. Particle number (Np) tends to increase with conversion for monomer mixtures rich in MeA, contrary to S homopolymerizations in which Np remains constant. Comparison of Np and kinetic data suggests that only part of the particles in actually active in polymerization (N*p). N*p can be estimated assuming that the average number of radical per particle, ñ remains close to 0,5 - as found in a previous study - which gives also an estimate of very tiny particles generated at low conversion and undetectable by the usual QELS and MET techniques. The experimental data, to some extent, allow to quantify the competition between micellar and homogeneous nucleation mechanisms.
    Additional Material: 15 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 641-648 
    ISSN: 0887-6266
    Keywords: polyethylene ; glass transition ; TSDC ; γ transition ; β transition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New thermally stimulated depolarization currents (TSDC) results on LLD polyethylene functionalized with diethylmaleate polar groups are precisely computer fitted with the direct signal analysis technique. It is shown that the TSDC spectrum consists, with increasing temperatures, of a sub-γ peak, a sharp γ peak, and a β and an α relaxation. The first peak is analyzed in terms of Arrhenius relaxation times, whereas the γ and β transitions could only be fitted by using Vogel-Fulcher temperature dependence for the relaxation times. The best value for To obtained from both fittings is 69.7 K. This is a quantitative proof for the identification of the γ transition as one of the dielectric manifestations of the glass-rubber transition for polyethylenes, Tg = 136.5 K, which has been discussed extensively in the literature. The β relaxation, Tgβ = 237 K, has also the expected characteristic of a glass transition; the existence of two Tgs in polyethylene could explain our results. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 1067-1074 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The nature of copper species of a series of alumina-supported copper samples was investigated by the kinetics of reduction, x-ray photoelectron spectroscopy, temperature-programmed desorption-mass spectrometry of chemisorbed NO and infrared spectroscopy of chemisorbed NO and CO probes. The role of these copper species was also examined in the catalytic decomposition of NO. The surface properties of copper were found to depend strongly on both Cu loading and calcination treatment. At Cu contents as low as 0.6 wt.%, Cu2+ ions from a well-dispersed interacting phase at the alumina surface, which upon calcination forms a surface spinel CuAl2O4. At copper contents up to 3.2 wt.%, both the surface spinel CuAl2O4 and a segregated CuO phase were clearly distinguished. The partial reduction of these species upon thermal treatment under high vacuum, the ability of the surface sites to chemisorb NO and CO probes and their implications in the catalytic decomposition of NO are discussed.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 14 (1989), S. 31-38 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The influence of instrumental parameters on the matrix effects (ion and sputtering yield variations) observed in AlxGa1 - xAs are critically evaluated. Ion and sputtering yield data from three different SIMS instruments (ARL IMMA, Cameca IMS-3F and Atomika SIMS) are examined. The influence of primary ion (O2 +) energy and incident angle on the extent of surface oxidation was examined using AES. Although relative ion yields varied linearly with the matrix composition in all instances, these ion yield variations differed greatly (a factor of 50) between instruments. These differences were attributed to differences in the surface oxygen concentrations produced by the SIMS instruments. AlAs was shown to be completely oxidized under each of the SIMS ion bombardment conditions. However, the oxygen levels incorporated in GaAs and the other Al poor specimens depended largely on the incident angle and to a lesser extent on the ion energy. Small incidence angles (normal incidence) promoted the most extensive oxidation of the Al-poor specimens, resulting in the smallest ion yield variations with matrix. As with the relative ion yields, relative sputtering yields varied linearly with the matrix composition in all instances. However, in contrast to relative ion yields, the relative sputtering yields did not change significantly under the different instrumental conditions. It was concluded that incident angle and ion energy had approximately the same influence on the sputtering yields obtained from the reference and the sample matrices. Thus, the relative sputtering yields were insensitive to changes in these ion beam parameters.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 3003-3006 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 14 (1976), S. 73-77 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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