948 research outputs found

    On the suitability of baked clay for archaeomagnetic studies as deduced from detailed rock-magnetic studies

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    Extensive rock-magnetic investigations have been carried out on baked clays from four kilns (two from Bulgaria and two from Switzerland) found in archaeological sites of different age. Knowledge of the magnetic characteristics of the grains responsible for the archaeomagnetic signal enables us to determine which baked clays have the stablest magnetization and why this is so. This is important in directional studies, but even more so in painstaking palaeointensity studies that require a very careful evaluation of the suitability of the burnt clay material. The proposed rock-magnetic experiments enable the identification of the carriers responsible for the remanence and an adequate interpretation of the experimental results connected with the palaeointensity evaluation. The experimental methods employed are illustrated with the particular results obtained from each of the four kilns studied. The preliminary elucidation of the magnetic mineralogy of the archaeological samples helps first by obtaining a more reliable palaeointensity result, and secondly by explaining some of the discrepancies in the palaeodirectional results. Examples of successful and failed palaeointensity experiments are given in relation to the magnetic properties previously established for each oven. The burnt-clay materials in this present study satisfy the essential condition of carrying a thermoremanence. In spite of that, it is shown that there are many factors that can produce undesirable magnetic properties and thus restrict the suitability of these materials for archaeomagnetic analysis. The most important factors influencing the magnetic behaviour during magneto-diagnostic experiments are: the degree of heating in antiquity, the initial composition of the unbaked material and the burial conditions. The large difference in heating temperatures within a particular archaeological feature is a major cause of variation in magnetic behaviour amongst individual specimens, and so preventing a successful pre-selection of specimens for palaeointensity experiments. Nevertheless, the study has shown a very good coincidence between the determined rock-magnetic characteristics and the success rate in palaeointensity evaluatio

    Integrating soil moisture measurements into pasture growth forecasting in New Zealand's hill country

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    Forecasting pasture growth in hill country landscapes requires information about soil water retention characteristics, which will help to quantify both water uptake, and its percolation below the root zone. Despite the importance of soil moisture data in pasture productivity predictions, current models use low-resolution estimates of water input into their soil water balance equations and plant growth simulations. As a result, they frequently fail to capture the spatial and temporal variability of soil moisture in hill country soils. Wireless Sensor Networks (WSN) are promising in-situ measurement systems for monitoring soil moisture dynamics with high temporal resolution in agricultural soils. This paper presents the deployment of a soil moisture sensing network, utilising WSN technology and multi-sensor probes, to monitor soil water changes over a hill country farm in the northern Wairarapa region of the North Island. Processed capacitance-based raw data was converted to volumetric water content by means of a factory calibration function to assess sensor accuracy and to calculate soil water storage within the pasture root zone. The derived volumetric soil moisture data was examined in terms of its dependence on the variability and influences of hill country landscape characteristics such as aspect. The integration of spatially distributed sensors and multi-depth soil moisture measurements from various hillslope positions showed that slope and aspect exerted a significant impact on soil moisture values. Furthermore, considerable differences were identified in soil water profile responses to significant rainfall events and subsequent soil water redistribution. Initial indications are that high-resolution time series of accurate multi-depth soil moisture measurements collected by a WSN are valuable for investigating root zone water movement. Sensor evaluation and data analysis suggest that these devices and their associated datasets are able to contribute to an improved understanding of drying and wetting cycles and soil moisture variability. Potentially, this will create an opportunity to generate improved pasture growth predictions in pastoral hill country environments

    COMMUNICATING MULTILEVEL EVACUATION CONTEXT USING SITUATED AUGMENTED REALITY

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    Emergency preparedness is a fundamental component of a successful emergency management strategy. This includes a proactive communication strategy that informs all stakeholders of the emergency plan and helps translate that knowledge to real spaces. Communicating multilevel built environments can be difficult, as the architectural complexity creates problems for both visual and mental representations of networks in 3D space. Modern mobile technology offers emerging opportunities for emergency managers to develop and deploy 3D visualizations of multilevel spaces that preserve the topology of those spaces while adding the spatial context that allows the individual to better understand their position within it. In this paper, we present a collection of mixed reality (specifically augmented reality) geovisualizations that overcome the visual limitations associated with the traditional static 2D methods of communicating the evacuation plans of multilevel structures. We demonstrate how this technology can provide spatially contextualized 3D geovisualizations that promote spatial knowledge acquisition and support cognitive mapping. These geovisualizations are designed as a proactive emergency management tool to educate and prepare at risk populations prior to the occurrence of a hazardous event

    Paleomagnetic reconnaissance of the grupo diábasico western andes (colombia)

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    A paleomagnetic reconnaissance has been carried out on the Grupo Diabásico of the western Cordillera from the Colombian Andes, between El Tambo and El Penol, Departamento Nariño. The Grupo Diabásico wich is of Cretaceous age is thought to be of submarine origin and to have undergone a low grade metamorphism.  The geometric mean of the natural remanent magnetization JNRM = 8.8 x 10-5 G. The low field magnetic susceptibility geometric mean X= 8.87 x 10-4G/Oe gives a Koenigsberger ratio of 0.28 indicating that the dominant magnetization is a induced one.Some pilot samples have been progressively demagnetized by alternating fields up to 600 O°. A viscous remanence test was applied to reject unstable sample. Despite the non ideal quality of the remanent magnetization a virtual geomagnetic pole has been calculated: pole latitude: 65° S; pole longitude: 186° E.A paleomagnetic reconnaissance has been carried out on the Grupo Diabásico of the western Cordillera from the Colombian Andes, between El Tambo and El Penol, Departamento Nariño. The Grupo Diabásico wich is of Cretaceous age is thought to be of submarine origin and to have undergone a low grade metamorphism.  The geometric mean of the natural remanent magnetization JNRM = 8.8 x 10-5 G. The low field magnetic susceptibility geometric mean X= 8.87 x 10-4G/Oe gives a Koenigsberger ratio of 0.28 indicating that the dominant magnetization is a induced one.Some pilot samples have been progressively demagnetized by alternating fields up to 600 O°. A viscous remanence test was applied to reject unstable sample. Despite the non ideal quality of the remanent magnetization a virtual geomagnetic pole has been calculated: pole latitude: 65° S; pole longitude: 186° E

    Nanoscale mobility mapping in semiconducting polymer films

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    This work was supported by grant No 19-12-00066 of the Russian Science Foundation.Local electrical properties of thin films of the polymer PTB7 are studied by conductive atomic force microscopy (C-AFM). Non-uniform nanoscale current distribution in the neat PTB7 film is revealed and connected with the existence of ordered PTB7 crystallites. The shape of local I-V curves is explained by the presence of space charge limited current. We modify an existing semi-empirical model for estimation of the nanoscale hole mobility from our experimental C-AFM measurements. The procedure of nanoscale charge mobility estimation was described and applied to the PTB7 films. The calculated average C-AFM hole mobility is in good agreement with macroscopic values reported for this material. Mapping of nanoscale hole mobility was achieved using the described procedure. Local mobility values, influenced by nanoscale structure, vary more than two times in value and have a root-mean-square value 0.22 × 10−8 m2/(Vs), which is almost 20% from average hole mobility.PostprintPeer reviewe

    Vacuum properties of TiZrV non-evaporable getter films

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    Sputter-deposited thin films of TiZrV are fully activated after 24 h "in situ" heating at 180 °C. This activation temperature is the lowest of some 18 different getter coatings studied so far, and it allows the use of the getter thin film technology with aluminium alloy vacuum chambers, which cannot be baked at temperatures higher than 200 °C.An updated review is given of the most recent results obtained on TiZrV coatings, covering the following topics: influence of the elemental composition and crystal structure on activation temperature, discharge gas trapping and degassing, dependence of pumping speed and surface saturation capacity on film morphology, ageing consequent to activation-air venting cycles and ultimate pressures. Furthermore, the results obtained when exposing a coated particle beam chamber to synchrotron radiation in a real accelerator environment (ESRF Grenoble) are presented and discussed

    Mapping hole mobility in PTB7 films at nanoscale

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    Funding: Federal Target Program of MES of Russian Federation, contract 14.575.21.0149 (RFMEFI57517X0149).The nanoscale hole mobility in organic semiconducting polymer PTB7 is quantified by using conductive-AFM (C-AFM) measurements in space charge limited (SCLC) regime. The obtained current map of the neat PTB7 film is explained in terms of non-uniform built-in voltage and variations of hole mobility. For mobility estimation, the semi-empirical model of SCLC, known from previous works, was modified and applied. It is found that the values of built-in voltage in C-AFM measurements are usually several times larger than ones derived from macroscopic measurements. It is also shown that value of hole mobility in PTB7 film depends on location and varies in more than two times. These mobility variations are connected with nanoscale film structure revealed by other methods.Publisher PD
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