bluuebunny/crossref_metadata_2025_split huggingface dataset:
RANGE–Robust autonomous navigation in GPS‐denied environments
Authors: Bachrach Abraham , Prentice Samuel , He Ruijie , Roy Nicholas 
Published: August 2011

AbstractThis paper addresses the problem of autonomous navigation of a micro air vehicle (MAV) in GPS‐denied environments. We present experimental validation and analysis for our system that enables a quadrotor helicopter, equipped with a laser range finder sensor, to autonomously explore and map unstructured and unknown environments. The key challenge for enabling GPS‐denied flight of a MAV is that the system must be able to estimate its position and velocity by sensing unknown environmental structure with sufficient accuracy and low enough latency to stably control the vehicle. Our solution overcomes this challenge in the face of MAV payload limitations imposed on sensing, computational, and communication resources. We first analyze the requirements to achieve fully autonomous quadrotor helicopter flight in GPS‐denied areas, highlighting the differences between ground and air robots that make it difficult to use algorithms developed for ground robots. We report on experiments that validate our solutions to key challenges, namely a multilevel sensing and control hierarchy that incorporates a high‐speed laser scan‐matching algorithm, data fusion filter, high‐level simultaneous localization and mapping, and a goal‐directed exploration module. These experiments illustrate the quadrotor helicopter's ability to accurately and autonomously navigate in a number of large‐scale unknown environments, both indoors and in the urban canyon. The system was further validated in the field by our winning entry in the 2009 International Aerial Robotics Competition, which required the quadrotor to autonomously enter a hazardous unknown environment through a window, explore the indoor structure without GPS, and search for a visual target. © 2011 Wiley Periodicals, Inc.
Aerial remote sensing in agriculture: A practical approach to area coverage and path planning for fleets of mini aerial robots
Authors: Barrientos Antonio , Colorado Julian , Cerro Jaime del , Martinez Alexander , Rossi Claudio , Sanz David , Valente João 
Published: August 2011

AbstractIn this paper, a system that allows applying precision agriculture techniques is described. The application is based on the deployment of a team of unmanned aerial vehicles that are able to take georeferenced pictures in order to create a full map by applying mosaicking procedures for postprocessing. The main contribution of this work is practical experimentation with an integrated tool. Contributions in different fields are also reported. Among them is a new one‐phase automatic task partitioning manager, which is based on negotiation among the aerial vehicles, considering their state and capabilities. Once the individual tasks are assigned, an optimal path planning algorithm is in charge of determining the best path for each vehicle to follow. Also, a robust flight control based on the use of a control law that improves the maneuverability of the quadrotors has been designed. A set of field tests was performed in order to analyze all the capabilities of the system, from task negotiations to final performance. These experiments also allowed testing control robustness under different weather conditions. © 2011 Wiley Periodicals, Inc.
AUTOMATIC DELINEATION OF FUNCTIONAL RIVER REACH BOUNDARIES FOR RIVER RESEARCH AND APPLICATIONS
Authors: Parker C. , Clifford N. J. , Thorne C. R. 
Published: August 2011

ABSTRACTThe river reach is a pervasive term within contemporary river research and applications. Yet, despite its prevalence, there is a notable lack of consistency in its definition. This paper identifies the presence of two broad types of reach definition within the academic literature, operational and functional, and argues that a functional definition is more suitable for applications within river research and management. A range of sequence zonation algorithms that were originally derived for geological well‐log analysis were compared for their ability to automatically identify functional reach boundaries. An analysis of variance‐based global boundary hunting algorithm was identified as the most suitable. To demonstrate the potential practical applications of automatic reach delineation methods, two case studies where functional reach boundaries have been identified were described: first, in a sequence of predicted sediment transport capacities for use in a reach‐based sediment transport model; and second, in a sequence of RHS Habitat Quality Assessment scores for identification of lengths of channel in need of habitat restoration efforts. Finally, the paper discusses how this type of functional reach identification procedure might be applied in other areas of river research and applications and how a multivariate version of a statistical zonation algorithm might prove useful in facilitating integrated catchment management by identifying reach boundaries common across all variables of interest in the system. Copyright © 2011 John Wiley & Sons, Ltd.
Surface roughness analysis of hardened steel after high‐speed milling
Authors: Twardowski Paweł , Wojciechowski Szymon , Wieczorowski Michał , Mathia Thomas 
Published: August 2011

AbstractThe work refers to analysis of various factors affecting surface roughness after end milling of hardened steel in high‐speed milling (HSM) conditions. Investigations of milling parameters (cutting speed vc, axial depth of cut ap) and the process dynamics that influence machined surface roughness were presented, and a surface roughness model, including cutter displacements, was elaborated. The work also involved analysis of surface profile charts from the point of view of vibrations and cutting force components.The research showed that theoretic surface roughness resulting from the kinematic–geometric projection of cutting edge in the workpiece is significantly different from the reality. The dominant factor in the research was not feed per tooth fz (according to the theoretical model) but dynamical phenomena and feed per revolution f. SCANNING 33: 386–395, 2011. © 2011 Wiley Periodicals, Inc.
Volume changes during preparation of mouse embryonic tissue for scanning electron microscopy
Authors: Boyde A. , MacOnnachie E. 
Published: August 2011

AbstractThis paper describes the results of experiments in which the volume changes in mouse embryo limb samples were followed more or less continuously after fixation through dehydration and critical point drying, with in some instances data relating to post critical point drying shrinkage.14 and 15 day p. c. mouse embryos were fixed in 3 % glutaraldehyde in cacodylate buffer and stored in this fixative until use. Single specimens were studied using a Quantimet image analysing computer to record the changes in projected area of the unmounted specimens as they were passed through the usual series of reagents according to various commonly used dehydration schedules. The area changes were converted to volume changes for the purposes of presentation in this paper. The Quantimet system could not be used to follow volume changes in the CPD bomb so that most experiments detail the volume in the intermediate fluid before CPD and the size of the specimen immediately after it was removed from the CPD bomb. A few experiments were conducted in which the specimens were measured whilst they were in the CPD bomb. The measurements relating to dehydration and CPD procedures were compared with measurements of air dried and freeze dried specimens.All three drying methods cause considerable shrinkage: freeze drying to 85 % of the glutaraldehyde fixed tissue volume; critical point drying to 41% (after 24 h); and air drying from a volatile solvent to about 18% of the fixed tissue volume. Air drying from water caused a shrinkage to about 12% of the original volume. There was no significant difference between the various commonly used CPD schedules or between GA only and GA + Os O4 fixed tissue. CPD via cellosolve and CO2 caused substantially more shrinkage than other methods.Dimensional changes during specimen preparation are probably associated with changes in shape and in relative relationships between organelles, cells and tissues having different compositions. This should be borne in mind by all those interpreting scanning electron micrographs of dried animal soft tissue specimens.
A preliminary study of the application of SEM to the study of coins
Authors: Kushelevsky A. P. , Meshorer Y. 
Published: August 2011

AbstractThe superior depth of focus of the SEM at low and high magnification provides important information regarding the minting techniques used to produce the coin. This information can be used as an additional criterion to authenticate questionable coins. The importance of preserving surface structure during cleaning processes of ancient coins is stressed.
Automatic electron microprobe analysis using energy dispersive spectrometry
Authors: Beswick J. M. 
Published: August 2011

AbstractThe use of mini computers in energy dispersive spectrometry is common in quantitative electron microprobe analysis. A modification to the Edax 707 multichannel analyser makes it possible to control the stage movement of an electron beam instrument via a suitable motor control unit and to restart the multichannel analyser. By use of a loop in the BASIC interactive computer programme any number of automatic microanalysis step determinations can be performed.
Problems with the preparation of blood vessels for scanning electron microscopy a critical review
Authors: Hollweg H. G. , Buss H. 
Published: August 2011

AbstractThe application of the scanning electron microscope (SEM) in the investigation of blood vessels in the last ten years is reviewed. Methodological differences from anesthesia of the experimental animal to mounting of the dried tissue specimen are discussed. Some of the major interpretative pitfalls are indicated and some practical guidelines for standardization are offered.
Depth profiling by secondary ion mass spectrometry
Authors: Zinner E. 
Published: August 2011

AbstractThe principles and applications of depth profiling by secondary ion mass spectrometry (SIMS) are reviewed. Discussed are the basic physical processes and instrumental factors which influence the shape of depth profiles and which have to be understood or controlled for successful experimental measurements. Microroughness caused by sputtering, atomic mixing by primary beam knock‐on, and sample consumption limit the depth resolution which can be achieved while the chemical effect of ion yield enhancement by reactive species, matrix effects, and preferential sputtering can strongly affect the secondary ion signal. Instrumental effects to be controlled include beam uniformity, sample charging, and beam, and residual gas contamination. High depth resolution and sensitivity are the reasons for a wide variety of applications for SIMS depth profiling. Reviewed are measurements of the range distribution of ions implanted into semiconductors and their redistribution by subsequent annealing, studies of thin films and of oxide layers, diffusion measurements in metals, semiconductors, and minerals, measurements of elemental surface enhancements in airborne particles, and lunar glass spherules, and the search for solar wind implanted ions in lunar crystals.
SIMS instrumentation and imaging techniques
Authors: Liebl H. 
Published: August 2011

AbstractSecondary ion mass spectrometry (SIMS) has evolved as a technique for characterizing solids and surfaces which is distinguished by high sensitivity and its applicability to all elements. It can be used for surface research, in‐depth concentration profiling, isotopic work, and the identification of compounds. Combined with imaging techniques, these applications can be made with high spatial resolution. In this respect, ion probe microanalysis complements electron probe microanalysis (XRMA and scanning AES).
Conductive staining in SEM with especial reference to tissue transparency
Authors: Gunji T. , Wakita M. , Kobayashi S. 
Published: August 2011

AbstractAlthough the number of applications of conductive staining for SEM has recently increased investigations or discussions on the features of these methods are scanty, and so it could not be said that its features are sufficiently understood. In the present studies employing the tannin‐osmium method as the conductive stain, the authors compared it with an ion‐sputtering method that they use for metal coating.Besides the prevention of masking by the coating metal, there are other advantages to the conductive staining method.
The appearance of the tissue “transparency”, which allows three‐dimensional observations of sub‐surface structures to be made.
Any damage associated with metal coating can be avoided since the specimen itself is conductive.
Hardening of specimens by the conductive stain enhances the resistance of structures to mechanical damage during preparation.
Especially the tissue transparency produced by the conductive stain might suggest new possibilities for SEM.
Preservation of the microbial association to intestinal mucosal epithelium in rats for scanning electron microscopy
Authors: Schellenberg D. A. , Pangborn J. 
Published: August 2011

AbstractA preparation technique for scanning electron microscopy (SEM) of the luminal surface of the intestinal mucosa was developed, with the objective of preserving the delicate interface between the microbial flora and the mucosal surface. The technique allows observation of the bacterial polysaccharide filaments and the structural features of the intestinal epithelium.
Preparation method for SEM and X‐ray projection microscopy of mouse embryos
Authors: Claussen C.‐P. , Louton M. , Hämel‐Hans D. 
Published: August 2011

AbstractIn this paper we described a new preparation method: Routine Bouin fixation of mammalian tissues (e.g. mouse‐embryos) allows not only light microscopy, but also SEM and x‐ray microscopic studies on the same samples. Bouin's fixative combined with 3% OsO4 postfixation gave best contrast in SEM and x‐ray projection microscopy.
The application of SEM and XRMA to the study of the structure and composition of Spanish mercury ores. A genesic hypothesis
Authors: Calvo F. A. , Guilemany J. Ma. , Ma de Salazar J. Gomez 
Published: August 2011

AbstractThis paper reports the results obtained by SEM and XRMA on the structure and constituents composition of different Spanish mercury ores. A new hypothesis to explain its genesis is proposed. Bearing in mind similarities and differences in the nature and number of minerals present and, their distribution on the ore, operations for more convenient beneficiation processes are suggested. Samples from Almadén (Ciudad Real), Caunedo (Oviedo), Tarna (León) and Chovar (Castellón), were studied.
Material surfaces for electron‐optical equipment
Authors: Anger K. , Lischke B. , Sturm M. 
Published: August 2011

AbstractElectron‐beam inspection systems for VLSICs and electron‐beam pattern generation require exact positioning of the electron beam on the specimen. In this connection the question arises as to what properties the walls and diaphragms in the ambience of the path of the electron beam are required to have with respect to material, surface layers and cleanness in order to exclude their collecting electric charges that will undesirably influence the electron beam.Experimental investigations of this problem by means of electron‐shadow projection show that the conductivity of a material should not be the sole criterion for its choice, but that its behavior under exposure to backscattered electrons and secondary electron emission must also be taken into account. Graphite of poor conductivity was found to be particularly favorable. Electroplated surfaces are often less favorable than untreated surfaces. Magnetic materials always exhibit minor defects. For cleaning, a carefully controlled ultrasonic technique using conventional cleaning agents is necessary and sufficient.
Colour micrographs for backscattered electron signals in the SEM
Authors: Danilatos G. D. 
Published: August 2011

AbstractThe backscattered electron (BSE) signals detected by a pair of detectors in the SEM can be used for producing colour micrographs. The image corresponding to any of these signals, or to a mixture of these signals, is assigned one primary colour and two or more of these images are superimposed onto the same colour frame. In addition, the mixing of signals from the gaseous detector device together with their use for colour imaging is also examined.
An SEM based system for a complete characterization of latch‐up in CMOS integrated circuits
Authors: Canali C. , Fantini F. , Giannini M. , Senin A. , Vanzi M. , Zanoni E. 
Published: August 2011

AbstractAn electron beam testing system was established for a complete and detailed analysis of latch‐up in CMOS integrated circuits. Problems which can be studied include:
identification of latch‐up current paths in steady state condition;
measurement of the local latch‐up sensitivity of the various parts of the circuit;
observation of the time evolution of latch‐up from the firing event to the final condition.
A Further Improvement in the Gaussian ϕ(ϱ) Approach for Matrix Correction in Quantitative Electron Probe Microanalysis
Authors: Bastin G. F. , Heijligers H. J. M. , van Loo F. J. J. 
Published: August 2011

AbstractAn improved correction model for quantitative electron probe microanalysis, based on modifications of the Gaussian ϕ(ϱ) approach, originally introduced by Packwood and Brown, is presented. The improvements consist of better equations for the input parameters of this model which have been obtained by fitting to experimental ϕ(ϱ) data. The new program has been tested on 627 measurements for medium to heavy elements (Z>11) and on 117 carbon measurements with excellent results: an r.m.s. value of 2.99% in the former case and 4.1% in the latter. Finally the new program has been compared to five other current correction programs which were found to perform less satisfactorily.
Intensity gradient techniques for orientation analysis of electron micrographs
Authors: Tovey N. K. , Smart P. 
Published: August 2011

AbstractThe variation in intensity between neighbouring picture points on an electron micrograph may be used to define an intensity gradient vector. This vector is related to the orientation of the feature at that point, and may be compared with similar vectors at all other points within the micrograph to obtain a quantitative measure of anisotropy. Alternatively, the results may be displayed graphically as a rosette diagram. This paper compares the results from using a simple ‘5‐point’, i.e. the nearest neighbours with those from alternative formulations for the intensity gradient vector. Generally, the increased number of points improves the shape of the rosette diagram by minimizing the likelihood of pronounced ‘spikes’ at certain critical angles which is a feature of the ‘5‐point’ method. The improved analysis requires an extra 60% computing time, which may be of significance if direct on‐line work is contemplated. Some examples of micrographs of soil microfabric are presented to illustrate the different methods.
Reduction of edge penetration effect in the scanning electron microscope
Authors: Wells Oliver C. 
Published: August 2011

AbstractElectron penetration into the sample in the scanning electron microscope can give rise to bright fringes close to sharp edges in the secondary electron image. This can make it difficult to see details close to the edge. These fringes can be considerably reduced by putting a positive control electrode (CE) between the specimen and the collector. This can be mounted with an insulated clip directly onto the specimen stub. The effectiveness of this technique is demonstrated for the case of a cleaved silicon wafer containing microelectronic structures. The action of the CE is explained in terms of the effective solid angle subtended by the collector at the surface of the specimen.
Stereological stereometry: Simplified approaches to volumetry by SEM
Authors: Boyde A. 
Published: August 2011

AbstractNew approximate methods for the measurement of volumes of pits in otherwise flat substrates are outlined: all are based on taking parallax measurements from SEM stereo‐pair images. The measured points lie at pre‐set intervals in a grid, the grid corresponding to the usual 2‐D array used in stereology and being used for the same purpose – that of determining area. Depth below the original surface is derived from the parallax at each point. Several practical alternatives for parallax measurement are considered, all involving relatively inexpensive instruments. The cheapest – and it remains to be determined whether also the most efficient – involves the use of a stereo‐pair grid overlay, called a “2D‐3D” grid. This grid exists physically in only two dimensions, but is seen to exist apparently in three dimensions.
TEM‐, SEM‐ and STEM‐studies of sputter‐coated cytoskeletons
Authors: Lindroth M. , Bell P. B. , Fredriksson B. A. 
Published: August 2011

AbstractA technique for sputter coating of cytoskeletons from detergent extracted cells is described. The method allows their study in high resolution TEM, SEM and STEM. The use of cytoskeletons is also a valuable model system for the evaluation of metal coating techniques, allowing studies of deposited metal on fine filamentous structures of varying thicknesses.Pt and W were sputtered at 1 to 5 nm, and comparisons were made with reference to contrast and granularity. Both metais gave good topographical contrast, but Pt showed a coarse structure and a greater decorating tendency than W.The method provides a simple system for studies of the three‐dimensional cytoskeletal organization, without the use of cumbersome replica‐techniques.
A new method for pulmonary edema research: Scanning electron microscopy of frozen‐hydrated edematous lung
Authors: Hook G. R. , Bastacky J. , Conhaim R. L. , Staub N. C. , Hayes T. L. 
Published: August 2011

AbstractWe present an integrative method for studying alveolar fluid accumulation during pulmonary edema using scanning electron microscopy (SEM) of frozen‐hydrated lung. We induced edema in dogs by fluid over‐loading the vascular system while monitoring vascular and airway pressures. Terminally, we freeze‐fixed the lungs in the open thorax while controlling airway pressure. Using a cryosample preparation chamber attached to a scanning electron microscope equipped with a low temperature stage, we in vacuo freeze‐fractured the lung, gold coated the fractured surface and used secondary electron emission scanning electron microscopy to examine the frozen‐hydrated lung with scanning electron micrographs of freeze‐dried and airway fixed, critical point dried lung. We discuss the advantages of frozen‐hydrated scanning lung preservation for pulmonary edema research, especially in regard to quantifying alveolar fluid distribution by stereo photogrammetry, and suggest areas of future research to improve the method.