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  • 1
    Publication Date: 2019-09-01
    Description: Coring sediments in subglacial aquatic environments offers unique opportunities for research on paleo-environments and paleo-climates because it can provide data from periods even earlier than ice cores, as well as the overlying ice histories, interactions between ice and the water system, life forms in extreme habitats, sedimentology, and stratigraphy. However, retrieving sediment cores from a subglacial environment faces more difficulties than sediment coring in oceans and lakes, resulting in low yields from the most current subglacial sediment coring methods. The coring tools should pass through a hot water-drilled access borehole, then the water column, to reach the sediment layers. The access boreholes are size-limited by the hot water drilling tools and techniques. These holes are drilled through ice up to 3000–4000 m thick, with diameters ranging from 10–60 cm, and with a refreezing closure rate of up to 6 mm/h after being drilled. Several purpose-built streamline corers have been developed to pass through access boreholes and collect the sediment core. The main coring objectives are as follows: (i) To obtain undisturbed water–sediment cores, either singly or as multi-cores and (ii) to obtain long cores with minimal stratigraphic deformation. Subglacial sediment coring methods use similar tools to those used in lake and ocean coring. These methods include the following: Gravity coring, push coring, piston coring, hammer or percussion coring, vibrocoring, and composite methods. Several core length records have been attained by different coring methods, including a 290 cm percussion core from the sub-ice-shelf seafloor, a 400 cm piston core from the sub-ice-stream, and a 170 cm gravity core from a subglacial lake. There are also several undisturbed water–sediment cores that have been obtained by gravity corers or hammer corers. Most current coring tools are deployed by winch and cable facilities on the ice surface. There are three main limitations for obtaining long sediment cores which determines coring tool development, as follows: Hot-water borehole radial size restriction, the sedimentary structure, and the coring techniques. In this paper, we provide a general view on current developments in coring tools, including the working principles, corer characteristics, operational methods, coring site locations, field conditions, coring results, and possible technical improvements. Future prospects in corer design and development are also discussed.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
    Publication Date: 2024-01-19
    Description: In this paper, the Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technology is adopted to monitor the Line of Sight (LOS) displacement of Fushun West Opencast Coal Mine (FWOCM) and its surrounding areas in northeast China using Sentinel-1 Synthetic Aperture Radar (SAR) images acquired from 2018 to 2022. The spatial-temporal evolution of urban subsidence and the south-slope landslide are both analyzed in detail. Comparison with ground measurements and cross-correlation analysis via cross wavelet transform with monthly precipitation data are also conducted, to analyze the influence factors of displacements in FWOCM. The monitoring results show that a subsidence basin appeared in the urban area near the eastern part of the north slope in 2018, with settlement center located at the intersection of E3000 and fault F1. The Qian Tai Shan (QTS) landslide on the south slope, which experienced rapid sliding during 2014 to 2016, presents seasonal deceleration and acceleration with precipitation, with the maximum displacement in vicinity of the Liushan paleochannel. The results of this paper have fully taken in account for the complications of large topographic relief, geological conditions, spatial distribution and temporal evolution characteristics of surface displacements in opencast mining area. The wide range and long time series dynamic monitoring of opencast mine are of great significance to ensure mine safety production and geological disaster prevention in the investigated mining area.
    Description: In press
    Description: OSA5: Energia e georisorse
    Description: JCR Journal
    Keywords: Multi-Temporal InSAR ; opencast mine ; landslide ; land subsidence ; cross wavelet transform
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 70 (1994), S. 281-290 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Directional and orientational components usually coexist and are mixed in the cell's overall responses when moving optical stimuli are used to study the response characteristics of visual neurons. While these two properties were quantified with all the previous methods for data analysis, their effects could not be efficiently separated from each other, and thus the analyses were imperfect. In this paper, theoretical evidence and examples are provided to show the defects of the old methods. In order to separate the two components completely, we propose to apply optimal regression analysis with the sine-cosine function series as the fundamental variables. Based on this separation, we defined the orientational selectivity as variation of response strength with orientation and performed integration and averaging to quantify the two properties [cf. Eqs. (5) and (6)]. The present method has the advantages of completeness and accuracy, and can detect some details which would have been missed by other methods. An explanation of the intrinsic implications of the method and our comprehension of directional and orientational selectivities and preferred direction and orientation are also given.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 70 (1994), S. 281-290 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. Directional and orientational components usually coexist and are mixed in the cell's overall responses when moving optical stimuli are used to study the response characteristics of visual neurons. While these two properties were quantified with all the previous methods for data analysis, their effects could not be efficiently separated from each other, and thus the analyses were imperfect. In this paper, theoretical evidence and examples are provided to show the defects of the old methods. In order to separate the two components completely, we propose to apply optimal regression analysis with the sine-cosine function series as the fundamental variables. Based on this separation, we defined the orientational selectivity as variation of response strength with orientation and performed integration and averaging to quantify the two properties [cf. Eqs. (5) and (6)]. The present method has the advantages of completeness and accuracy, and can detect some details which would have been missed by other methods. An explanation of the intrinsic implications of the method and our comprehension of directional and orientational selectivities and preferred direction and orientation are also given.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 334-335 (Mar. 2007), p. 1069-1072 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In recent years, chitosan/inorganic composites have attracted increasing attention due toits fascinating properties and potential applications in biodegradable materials, drug release,electrochemical sensor, packaging materials and so on. Chitosan/inorganic composites are expectedto be as an effective way to overcome shortcomings of slow flocculating speed of chitosan particles,not good enough to meet those wide range of applications in wasterwater treatment. In this study,novel chitosan/clay/PAC (polyaluminium chloride) composite was prepared, and it was used intreating effluent from dying and finishing process. One set of orthogonal experiments wereconducted to optimize the experimental condition, and the results showed that removal of waste dyeis affected by the dosage of chitosan, PAC, clay, pH and treatment time. The experiments resultsindicated that the effluent from dying and finishing process treated by the prepared compositesbecame obviously fade, and its COD (chemical oxygen demand) decreased from original1398.2mg/L to 197.6mg/L, the removing rate reached 85.9%
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 339 (May 2007), p. 131-135 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Rapid reverse technology is one of the key technologies with which the enterprisesdevelop new product and occupy the market rapidly. How to realize the reverse measurement andCAD geometry reconstruction rapidly and accurately is always the most important focus for theresearchers. Based on the laser scanning technology, the realization principle of the laser linescanning measuring system is presented and the approaches to improve the precision are alsoanalysed in the paper. The self-adaptation adjustment of the probe position can move the light knifeimage to the optimal imaging area of the CCD according to the calibration result, which will ensurethe measurement precision of the CCD image. With the inner velocity loop and outer position loopfeedback control, the simple axis position precision of the mechanical system can be controlledwithin 5um. In order to pick up the points of the light knife centre rationally and exactly, thereconstruction-disperse iteration algorithm is put forward. After processed by different iterationtimes, the optimal points can be obtained. The reconstruction method of curve and surface based onNURBS is also given. The paper presents the application and realization of the system at last, whichrealizes the curve and surface measurement with high precision
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 334-335 (Mar. 2007), p. 833-836 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 334-335 (Mar. 2007), p. 825-828 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: It was shown that chitosan and hydroxy-aluminum pillared montmorillonites wereexcellent materials for the removal of dyes and metal ions from effluent of dying and finishing.Chitosan/ hydroxy-aluminum pillared montmorillonite nanocomposites are expected to play amultiplex role in the treating process. In this study, the nanocomposite was prepared by incorporatinghydroxy-aluminum pillared montmorillonite into chitosan solution that diluted acetic acid was usedas solvent for dissolving the chitosan. The ratio of chitosan to the cationic exchange capacity of themontmorillonite was about 1:1, 2:1, 3:1, 4:1 and 6:1, respectively. The nanocomposites werecharacterized by XRD (X-ray diffraction), SEM (Scanning Electron Microscopy). The experimentalresults indicated that the presence of hydroxy-aluminum cation was in favor of the chitosanintercalation and the interlayers of MMT was intercalated with the bilayers of chitosan sheets. andthey can be used in absorption of organic and metal ions for dying and finishing effluent
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 363-368 
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The explicit numerical method is used to trace the impact procedure of the tube columnsimpacted by a rigid body. The bar and rectangle tube models are both used to simulate the tubecolumn. The elastic and elas-plastic impact load with different mass ratio and impact speed areobtained. The calculation results show that: for elastic models, the bigger the mass ratio and thehigher the rigid body speed, the bigger the peak value of elastic impact load; at the same time, themore obvious the reduction effect of local buckling of rectangle tube on the peak value of impact loadand the longer the contact time of tube model; so the peak value of impact load of the rectangle tube isnot proportional to the rigid body speed. The stress wave in the tube causes a little difference betweenthe load curves of tube model and bar model. For elas-plastic models, the higher the rigid body speedand the smaller the mass ratio, the bigger the peak value of impact load and the longer the contacttime. The higher the rigid body speed, the bigger the difference between elastic and elas-plasticimpact load peak value due to the expanding of plasticity. Because of the effect of local buckling, thepeak value of elas-plastic impact load of rectangle tube is always lower than that of bar
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 336-338 (Apr. 2007), p. 1806-1809 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Biomechanical models of implanting prostheses into femora by means of press fit, i.e. themechanics of non-homogeneous layer-like composites, have been used to quantify the press-fit strengthand circumferential stress of the interface, when femora are partially replaced by different thicknesses ofbioactive ceramic coatings on a prosthesis surface during the initial implant stage. The maximum press-fitstrength appears on the interface between femora and Ti alloy prostheses with non-coating; the press-fitstrength decreases with the increased thickness of the coating. The circumferential stress displayed as thelarge tensile stress at the femoral side of the interface; the compressive stress, appeared at the side of thecoating and Ti alloy prosthesis. The shearing strength, jointing between the prostheses and femora wouldbe bigger with the thinner bioactive ceramic coatings. Considering the biodegradability of bioactiveceramic coatings, e.g. hydroxyapatite, HA, it is concluded that the optimum thickness of the bioactiveceramic coatings will be about 50-60 microns
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