3D terrain mapping and filtering from coarse resolution data cubes extracted from real-aperture 94 GHz radar

Funding: William D. Harcourt was funded by the Engineering and Physical Sciences Research Council (EPSRC; grant number: EP/R513337/1) and the Scottish Alliance for Geoscience, Environment and Society (SAGES).Accurate, high-resolution 3-D mapping of environmental terrain is critical in a range of disciplines. In this study, we develop a new technique, called the PCFilt-94 algorithm, to extract 3-D point clouds from coarse-resolution millimeter-wave radar data cubes and quantify their associated uncertainties. A technique to noncoherently average neighboring waveforms surrounding each AVTIS2 range profile was developed to reduce speckles and was found to reduce point cloud uncertainty by 13% at long range and 20% at short range. Furthermore, a Voronoi-based point cloud outlier removal algorithm was implemented, which iteratively removes outliers in a point cloud until the process converges to the removal of 0 points. Taken together, the new processing methodology produces a stable point cloud, which means that: 1) it is repeatable even when using different point cloud extraction and filtering parameter values during preprocessing and 2) is less sensitive to overfiltering through the point cloud processing workflow. Using an optimal number of ground control points (GCPs) for georeferencing, which was determined to be 3 at close ranges (3 km), point cloud uncertainty was estimated to be approximately 1.5 m at 1.5 km to 3 m at 3 km and followed a Lorentzian distribution. These uncertainties are smaller than those reported for other close-range radar systems used for terrain mapping. The results of this study should be used as a benchmark for future application of millimeter-wave radar systems for 3-D terrain mapping.Peer reviewe

Spatial analysis of Des Moines Lobe washboard moraines using LiDAR data

Washboard moraines are a characteristic landform of the Des Moines Lobe. Primarily composed of late Wisconsinan till and oriented parallel to and up-glacier from more conspicuous end moraines, washboard moraines are of low relief (1-2m) and appear to be regularly spaced. These moraines have been assumed in Des Moines Lobe reconstructions to have formed subglacially as basal crevasse fills, with crests developing perpendicular to the ice-flow direction when the lobe was at its maximum extent. Alternatively, the moraines are push moraines formed by seasonal advances of the lobe during its overall recession. The veracity of geomorphic reconstructions of the lobe\u27s thickness relies upon the former hypothesis being correct. The morphologies and spatial patterns of the moraines may help reveal their origin but are poorly characterized, owing to the topographic subtlety of the moraines. The acquisition of 1 m LiDAR over the Des Moines Lobe\u27s footprint allows washboard moraines to be spatially characterized over broad areas for the first time. After mapping LIDAR-derived elevation data and identifying suitable tracts of moraines, spatial analysis techniques are applied to study moraine spacing and cross-sectional profiles. Using a chi-square test with a significance level of 95%, Fourier analysis of 400 topographic profiles constructed perpendicular to moraine trends reveals a dominant, statistically significant wavelength of 90-110 m. Uniform moraine spacing is expected for crevasse-fill ridges but not for end moraines. The cross-sectional profiles of individual, de-trended moraines are stacked to characterize the average moraine shape. This exercise indicates that they lack the systematic asymmetry typically displayed by push-style end moraines, which are generally steeper on their down-glacier sides. Analysis of abrupt changes in moraine trend, called cusps, indicates that they occur preferentially in the vicinity of outwash trains of sand and gravel: all cusps point up-glacier, and 62.7% are coincident with surface outwash trains. Importantly, well logs indicate that remaining cusps are coincident with subsurface outwash overlain by till, indicating that the outwash pre-dates the last glacier advance and lending support to the hypothesis that subglacial outwash controlled the positions of cusp axes. Outwash trains may have supported anomalously low subglacial water pressures, thereby slowing basal slip in their vicinity and rotating basal crevasses to form the ridge cusps after glacier stagnation. These findings are consistent the Des Moines Lobe undergoing surge-like motion, with longitudinal extension creating transverse crevasses and stagnation allowing weak basal till to intrude upward into them

Intelligent Multi-Modal Sensing-Communication Integration: Synesthesia of Machines

In the era of sixth-generation (6G) wireless communications, integrated sensing and communications (ISAC) is recognized as a promising solution to upgrade the physical system by endowing wireless communications with sensing capability. Existing ISAC is mainly oriented to static scenarios with radio-frequency (RF) sensors being the primary participants, thus lacking a comprehensive environment feature characterization and facing a severe performance bottleneck in dynamic environments. To date, extensive surveys on ISAC have been conducted but are limited to summarizing RF-based radar sensing. Currently, some research efforts have been devoted to exploring multi-modal sensing-communication integration but still lack a comprehensive review. Therefore, we generalize the concept of ISAC inspired by human synesthesia to establish a unified framework of intelligent multi-modal sensing-communication integration and provide a comprehensive review under such a framework in this paper. The so-termed Synesthesia of Machines (SoM) gives the clearest cognition of such intelligent integration and details its paradigm for the first time. We commence by justifying the necessity of the new paradigm. Subsequently, we offer a definition of SoM and zoom into the detailed paradigm, which is summarized as three operation modes. To facilitate SoM research, we overview the prerequisite of SoM research, i.e., mixed multi-modal (MMM) datasets. Then, we introduce the mapping relationships between multi-modal sensing and communications. Afterward, we cover the technological review on SoM-enhance-based and SoM-concert-based applications. To corroborate the superiority of SoM, we also present simulation results related to dual-function waveform and predictive beamforming design. Finally, we propose some potential directions to inspire future research efforts.Comment: This paper has been accepted by IEEE Communications Surveys & Tutorial

Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development

The 1991 International Aerospace and Ground Conference on Lightning and Static Electricity, volume 2

The proceedings of the conference are reported. The conference focussed on lightning protection, detection, and forecasting. The conference was divided into 26 sessions based on research in lightning, static electricity, modeling, and mapping. These sessions spanned the spectrum from basic science to engineering, concentrating on lightning prediction and detection and on safety for ground facilities, aircraft, and aerospace vehicles

NASA thesaurus. Volume 3: Definitions

Publication of NASA Thesaurus definitions began with Supplement 1 to the 1985 NASA Thesaurus. The definitions given here represent the complete file of over 3,200 definitions, complimented by nearly 1,000 use references. Definitions of more common or general scientific terms are given a NASA slant if one exists. Certain terms are not defined as a matter of policy: common names, chemical elements, specific models of computers, and nontechnical terms. The NASA Thesaurus predates by a number of years the systematic effort to define terms, therefore not all Thesaurus terms have been defined. Nevertheless, definitions of older terms are continually being added. The following data are provided for each entry: term in uppercase/lowercase form, definition, source, and year the term (not the definition) was added to the NASA Thesaurus. The NASA History Office is the authority for capitalization in satellite and spacecraft names. Definitions with no source given were constructed by lexicographers at the NASA Scientific and Technical Information (STI) Facility who rely on the following sources for their information: experts in the field, literature searches from the NASA STI database, and specialized references

Photodetectors

In this book some recent advances in development of photodetectors and photodetection systems for specific applications are included. In the first section of the book nine different types of photodetectors and their characteristics are presented. Next, some theoretical aspects and simulations are discussed. The last eight chapters are devoted to the development of photodetection systems for imaging, particle size analysis, transfers of time, measurement of vibrations, magnetic field, polarization of light, and particle energy. The book is addressed to students, engineers, and researchers working in the field of photonics and advanced technologies

Engineering Effective Hamiltonians for Magnetic Resonance

Effective Hamiltonian engineering is a powerful technique that utilises time-dependent perturbation theory to suppress or enhance certain effects that arise from otherwise weak Hamiltonian terms, when an experimenter attempts to control the evolution of a quantum system. With this thesis we conduct theoretical, numerical and experimental explorations of two somewhat different kinds of effective Hamiltonian engineering in magnetic resonance, aimed at elongating spin coherence times and increasing spin polarization. First, we provide a general framework for computing arbitrary time-dependent perturbation theory terms relevant for effective Hamiltonian engineering, as well as their gradients with respect to control variations, that immediately enables the use of gradient methods for optimizing these terms. We demonstrate the method in various numerical control engineering examples, including decoupling, recoupling, and robustness to control errors and stochastic errors. We then utilize the method in high-resolution nanoscale magnetic resonance experiments that use high-sensitivity silicon nanowire based force detection. With our numerically engineered control sequences, that are optimized to suppress spin decoherence under dipolar and chemical shift Hamiltonians, we achieve an increase by a factor of 500 in the proton spin coherence time for low-temperature, (50-nm)^3 polystyrene sample. We harness the enhanced spin coherence times for magnetic resonance imaging experiments on the nanoscale, and achieve one-dimensional imaging resolution below 2 nm on the same sample. Secondly, we study low-temperature, high magnetic field nuclear hyperpolarization of phosphorus donor nuclei in isotopically enriched 28-silicon crystal irradiated with nonresonant above band gap laser light. We demonstrate hyperpolarization with a time constant of 51.5 s, and introduce a phonon-mediated effective Hamiltonian model detailing the process. We verify our model by designing and conducting a series of magnetic resonance experiments