Bayesian Deep Learning for Spatial Interpolation in the Presence of Auxiliary Information

Mathematical Geosciences - Earth scientists increasingly deal with ‘big data’. For spatial interpolation tasks, variants of kriging have long been regarded as the established...     

The effect of gauge length on axially incident P‐waves measured using fibre optic distributed vibration sensing

Distributed vibration sensing, also known as distributed acoustic sensing, is a relatively new method for recording vertical seismic profile data using a fibre optic cable as the sensor. The signal obtained from such systems is a distributed measurement over a length of fibre referred to as the gauge length. In this paper, we show that gauge length selection is one of the most important acquisition parameters for a distributed vibration sensing survey. If the gauge length is too small, then the signal‐to‐noise ratio will be poor. If the gauge length is too large, resolution will be reduced and the shape of the wavelet will be distorted. The optimum gauge length, as derived here, is a function of the velocity and frequencies of the seismic waves being measured. If these attributes vary considerably over the depth of a survey, then the use of different gauge lengths is recommended. The significant increases in data quality resulting from the use of multiple gauge length values are demonstrated using field data.     

Dark clasts in the Khor Temiki aubrite: Not basalts

Abstract— The enstatite achondrite meteorites (aubrites) are ultramafic assemblages with highly variable bulk rare earth element (REE) compositions. An enrichment of REE in a dark clast from the Khor Temiki aubrite led Wolf et al. (1983) to suggest that such dark clasts could be the basaltic (i.e., enstatite-plagioclase) complements to the ultramafic aubrites, with the relatively high REE contents resulting from the presence of plagioclase, which is a common carrier of the REEs. We have studied several dark clasts from the Khor Temiki aubrite and find no evidence for a basaltic character for such material. The microscopic character of the dark clasts is not significantly different from the main portions of Khor Temiki and consists either of highly brecciated material, containing a fine-grained matrix, or of enstatite grains with abundant inclusions. We suggest that the dark clasts are shock-darkened, heterogeneous Khor Temiki material that, by chance, contained variable trace contents of oldhamite (CaS), which has been shown to be a major carrier of REE in aubrites. We find that the REE contents of the clasts range from 0.1 to ～20× CI. Most have negative Eu anomalies, but one has a small positive anomaly. Extensive searches have failed to identify basaltic material in Khor Temiki and other aubrites. The absence of basaltic material is consistent with, but does not prove, the model of Wilson and Keil (1991). They calculate that, on an asteroidal parent body < ～100 km in radius, a volatile-rich basaltic partial melt erupted with a velocity greater than the escape velocity of the asteroid and, thus, was lost into space ～ 4.55 Ga ago.     

An intelligent spatial land use planning support system using socially rational agents

This research presents an intelligent planning support system based on multi-agent systems for spatial urban land use planning. The proposed system consists of two main phases: a pre-negotiation phase and an automated negotiation phase. The pre-negotiation phase involves interaction between human actors and intelligent software agents in order to elicit the actors’ social preferences. The agents employ social value orientation theory, which is rooted in social psychology, in order to model actors’ social preferences. The automated negotiation phase involves negotiation among autonomous software agents, the aim being to achieve consensus about the spatial problem on behalf of the relevant actors and using the information obtained.

This study employs a computationally effective Bayesian learning technique, along with social value orientation theory, to design socially rational intelligent agents who work on behalf of real actors. The proposed system is applied to a real world urban land use planning case study. Human actors participate in a pre-negotiation phase, and their social preferences are elicited by intelligent software agents through a number of interactions. Then, software agents come together to engage in an automated negotiation phase and eventually reach an agreement on the spatial configuration of urban land uses on behalf of the actors. The results of the study show that the proposed system is effective at performing an automated negotiation, plus that the final plan – which is the output of the automated negotiation – produces higher social utility and better spatial land use configurations for the agents.     

Peripherality in the global container shipping network: the case of the Southern African container port system

Regional trade co-operation, economic growth and greater political stability have enabled increased container throughput and container port capacity development. Earlier academic work has indicated that the functional position of this port region in the global maritime network might be shifting from a remote region in the periphery of the network to a more intermediate position. This paper aims to analyze the changing level of peripherality and remoteness of the Southern African container port system as part of the global container shipping network. The central hypothesis is that Southern Africa has moved from a remote shipping region to a more central shipping region in the global network. The methodology consists of the calculation of network measures for Southern African ports. The changing geographical distribution of flows among the main container ports in South Africa, Namibia, Mozambique, Mauritius and Madagascar will also be explored in terms of their respective shipping services, port calling patterns, market structure (in terms of the number of active carriers) and the up-scaling of vessel and port capacity. The overall result is a mapped port hierarchical structure with a clear indication of the shifted maritime centrality of Southern African ports from 1996 to the present decade.     

Integration zeitabhängiger Funktionen mittels Glimmröhren-Kippschwinger

Zusammenfassung Es wird ein im wesentlichen aus einem einfachen Kippschwinger bestehender Integrator beschrieben, der es gestattet, zeitlich veränderliche Spannungen digital zu summieren. Er ist somit zur Integration von zeitlich variablen Meßgrößen, insbesondere aus Meteorologie und Geophysik, sie sich in eine der Meßgröße proportionale Spannung umsetzen lassen, geeignet. Es werden Meß- und Anwendungsbeispiele gegeben.

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Summary An integration device consisting essentially of a simple saw-tooth oscillator is described. The instrument allows to integrate arbitrary voltages variable with time. Thus it is possible to integrate measuring functions variable with time, especially in meteorology and geophysics, that are convertible into a proportional voltage. Examples of measurements and application are represented.

     

Iap general circulation models: a first step towards developing a local area model for weather prediction in nigeria

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Investigating dune-building feedback at the plant level: Insights from a multispecies field experiment

Coastal foredunes provide the first line of defense against rising sea levels and storm surge and for this reason there is increasing interest in understanding and modeling foredune formation and post-storm recovery. However, there is limited observational data available to provide empirical guidance for the development of model parameterizations. To provide guidance for improved representation of dune grass growth in models, we conducted a two-year multi-species transplant experiment on Hog Island, VA, U.S.A. and measured the dependence of plant growth on elevation and distance from the shoreline, as well as the relationship between plant growth and sand accumulation. We tracked total leaf growth (length) and aboveground leaf length and found that Ammophila breviligulata (American beachgrass) and Uniola paniculata (sea oats) grew more than Spartina patens (saltmeadow cordgrass) by a factor of 15% (though not statistically significant) and 45%, respectively. Our results also suggest a range of basal/frontal area ratios (an important model parameter) from 0.5-1 and a strong correlation between transplant growth and total sand deposition for all species at the scale of two years, but not over shorter temporal scales. Distance from the shoreline and elevation had no effect on transplant growth rate but did have an effect on survival. Based on transplant survival, the seaward limit of vegetation at the end of the experiment was approximately 30 m from the MHWL and at an elevation of 1.43 m, corresponding to inundation less than 7.5% of the time according to total water level calculations. Results from this experiment provide evidence for the dune-building capacity of all three species, suggesting S. patens is not a maintainer species, as previously thought, but rather a moderate dune builder even though its growth is less stimulated by sand deposition than A. breviligulata and U. paniculata. © 2019 John Wiley & Sons, Ltd.