Close-range hyperspectral imaging for geological field studies: workflow and methods

Close-range hyperspectral imaging is a new method for geological research, in which imaging spectrometry is applied from the ground, allowing the mineralogy and lithology in near-vertical cliff sections to be studied in detail. Contemporary outcrop studies often make use of photorealistic three-dimensional (3D) models, derived from terrestrial laser scanning (lidar), that facilitate geological interpretation of geometric features. Hyperspectral imaging provides complementary geochemical information that can be combined with lidar models, enhancing quantitative and qualitative analyses. This article describes a complete workflow for applying close-range hyperspectral imaging, from planning the optimal scan conditions and data acquisition, through pre-processing the hyperspectral imagery and spectral mapping, integration with lidar photorealistic 3D models, and analysis of the geological results. Pre-processing of the hyperspectral images involves the reduction of scanner artefacts and image discontinuities, as well as relative reflectance calibration using empirical line correction, based on two calibrated reflection targets. Signal-to-noise ratios better than 70:1 are achieved for materials with 50% reflectance. The lidar-based models are textured with products such as hyperspectral classification maps. Examples from carbonate and siliciclastic geological environments are presented, with results showing that spectrally similar material, such as different dolomite types or sandstone and siltstone, can be distinguished and spectrally mapped. This workflow offers a novel and flexible technique for applications, in which a close-range instrument setup is required and the spatial distribution of minerals or chemical variations is valuable.     

Optimizing Disparity for Motion in Depth

Beyond the careful design of stereo acquisition equipment and rendering algorithms, disparity post‐processing has recently received much attention, where one of the key tasks is to compress the originally large disparity range to avoid viewing discomfort. The perception of dynamic stereo content however, relies on reproducing the full disparity‐time volume that a scene point undergoes in motion. This volume can be strongly distorted in manipulation, which is only concerned with changing disparity at one instant in time, even if the temporal coherence of that change is maintained. We propose an optimization to preserve stereo motion of content that was subject to an arbitrary disparity manipulation, based on a perceptual model of temporal disparity changes. Furthermore, we introduce a novel 3D warping technique to create stereo image pairs that conform to this optimized disparity map. The paper concludes with perceptual studies of motion reproduction quality and task performance in a simple game, showing how our optimization can achieve both viewing comfort and faithful stereo motion.     

Principles of Branching Morphology and Anatomy in Arborescent Monocotyledons and Columnar Cacti as Concept Generators for Branched Fiber‐Reinforced Composites

The branching of arborescent (tree‐like) monocotyledonous plants of the genus Dracaena or of columnar cacti differ considerably from that observed in other dicotyledonous or gymnosperm trees. The investigated ramifications exhibit distinctive morphological and anatomical features. In arborescent monocotyledons the side branches are attached to the main stem by a fiber‐reinforced tissue newly formed during secondary growth, clasping the main stem and finally resulting in a “flange‐mounted” structure. In the case of columnar cacti the most obvious feature is the pronounced constriction at the attachment point of the branches that is also mirrored in the lignified vascular tissue. One might argue that these characteristic morphological and anatomical features in regions exposed to high mechanical stresses represent structural weaknesses. However, the outer shape and the inner structures of the ramifications cause considerable stability and structural integrity of the stem‐branch connection under static and dynamic loading. Our results allow concluding that load‐adaptation in ramified plant structures is a result of a combination of optimization in outer shape and fiber arrangement within the ramifications. Numerical methods simulating the mechanical behavior based on data obtained from the studied plants support this assumption. A deeper understanding of the outer shape of the connection between shoot and branch as well as of the arrangement of the lignified vascular tissues in the branching region, may contribute toward alternative concepts for branched technical light‐weight‐structures. In particular for braided fiber‐reinforced composites this biomimetic approach might help to keep the demand on the available design space as small as possible.     

Operational Considerations for Teaming Manned and Unmanned Helicopter

“Manned-Unmanned Teaming” among others refers to the use of an unmanned, flying sensor. One use for this is as an integral part of air units’ flying systems. Secondly, it can be used as an independent, recessed robotic component during missions, even from far away and ahead of time. As part of the German R&T project “Manned- Unmanned Teaming” (MUM-T), Elektroniksystem- und Logistik-GmbH (ESG) was assigned the task of investigating these concepts and the options for their realization. The focus of the investigation was initial operation capability within a narrow time frame concentrating on German Army Aviation helicopters. The paper focuses on the results achieved by ESG and begins with a short project overview. In the main part a representative MUM-T mission based on a personnel recovery mission is presented. The mission was demonstrated by ESG in close cooperation with German Army Aviation Combat Development Division (Ger AAV CDD). Beside operational aspects, technical aspects will be discussed. The lecture will close with a short outlook on the next steps, bringing MUM-T missions into service.     

An introduction to DNA microarrays for gene expression analysis

This tutorial presents a basic introduction to DNA microarrays as employed for gene expression analysis, approaching the subject from a chemometrics perspective. The emphasis is on describing the nature of the measurement process, from the platforms used to a few of the standard higher-level data analysis tools employed. Topics include experimental design, detection, image processing, measurement errors, ratio calculation, background correction, normalization, and higher-level data processing. The objective is to present the chemometrician with as clear a picture as possible of an evolving technology so that the strengths and limitations of DNA microarrays are appreciated. Although the focus is primarily on spotted, two-color microarrays, a significant discussion of single-channel, lithographic arrays is also included.     

Pathways and pitfalls of implementing the use of woodfuels in Germany's bioenergy sector

The paper presents an empirical study on the use of woody biomass for energy supply in Germany and the federal state of Brandenburg. It aims to explain the role forestry enterprises have for bioenergy provision in this area. The ‘Institutions of Sustainability’ framework is used as an analytical tool to investigate the role of private and public actors in these transactions, respectively, in the governance structures they are subject to. Empirical evidence was gathered by in-depth interviews with actors from forestry and bioenergy practice. Triggered by favorable governance structures, i.e. strong support by national and regional policies, rising prices for fossil energy sources, and co-operation of committed individuals and groups, a new bioenergy industry has been successfully established. However, the forestry sector has so far been just a marginal fuel supplier for this industry. The study identifies pitfalls impeding a broad implementation of wood-energy supply in forestry: not cost-covering prices offered by the bioenergy sector, lacking market transparency and security of supply, lacking mobilization of forest wood, and a preference among forest managers to sell products to the wood-processing industry. In terms of the Institutions of Sustainability the properties of transactions (asset specificities, uncertainties, separability), characteristics of actors (values, rationality) and governance structures (long-term contractual obligations elsewhere) are decisive in explaining the current form of transaction.     

Term rewriting and beyond — theorem proving in Isabelle

The subject of this paper is theorem proving based on rewriting and induction. Both principles are implemented as tactics within the generic theorem prover Isabelle. Isabelle's higher-order features enable us to go beyond first-order rewriting and express rewriting with conditionals, induction schemata, higher-order functions and program transformers. Applications include the verification and transformation of functional versions of insertion sort and quicksort.     

Using a molten organic conducting material to infiltrate a nanoporous semiconductor film and its use in solid-state dye-sensitized solar cells

We describe a method to fill thin films of nanoporous TiO₂ with solid organic hole-conducting materials and demonstrate the procedure specifically for use in the preparation of dye-sensitized solar cells. Cross-sections of the films were investigated by scanning electron microscopy and it was observed that a hot molten organic material fills pores that are 10 μm below the surface of the film. We characterized the incident photon to current conversion efficiency properties of the solid TiO₂/organic dye/organic hole-conductor heterojunctions and the spectra show that the dye is still active after the melting process.     

When to use bit-wise neutrality

Representation techniques are important issues when designing successful evolutionary algorithms. Within this field the use of neutrality plays an important role. We examine the use of bit-wise neutrality introduced by Poli and López (2007) from a theoretical point of view and show that this mechanism only enhances mutation-based evolutionary algorithms if not the same number of genotypic bits for each phenotypic bit is used. Using different numbers of genotypic bits for the bits in the phenome we point out by rigorous runtime analyses that it may reduce the optimization time significantly.     

A dynamic mesh refinement technique for Lattice Boltzmann simulations on octree-like grids

In this contribution, we present our new adaptive Lattice Boltzmann implementation within the Peano framework, with special focus on nanoscale particle transport problems. With the continuum hypothesis not holding anymore on these small scales, new physical effects—such as Brownian fluctuations—need to be incorporated. We explain the overall layout of the application, including memory layout and access, and shortly review the adaptive algorithm. The scheme is validated by different benchmark computations in two and three dimensions. An extension to dynamically changing grids and a spatially adaptive approach to fluctuating hydrodynamics, allowing for the thermalisation of the fluid in particular regions of interest, is proposed. Both dynamic adaptivity and adaptive fluctuating hydrodynamics are validated separately in simulations of particle transport problems. The application of this scheme to an oscillating particle in a nanopore illustrates the importance of Brownian fluctuations in such setups.