Shallow water bathymetry inversion using hybrid multi-band composites resulted from integration of drone-based RGB and multispectral imagery

Shallow bathymetry inversion algorithms have long been applied in various types of remote sensing imagery with relative success. However, this approach requires that imagery with increased radiometric resolution in the visible spectrum is available. The recent developments in drones and camera sensors allow for testing current inversion techniques on new types of datasets. This study explores the bathymetric mapping capabilities of fused RGB and multispectral imagery, as an alternative to costly hyperspectral sensors. Combining drone-based RGB and multispectral imagery into a single cube dataset, provides the necessary radiometric detail for shallow bathymetry inversion applications. This technique is based on commercial and open-source software and does not require input of reference depth measurements in contrast to other approaches. The robustness of this method was tested on three different coastal sites with contrasting seafloor types. The use of suitable end-member spectra which are representative of the seafloor types of the study area and the sun zenith angle are important parameters in model tuning. The results of this study show good correlation (R2>0.7) and less than half a meter error when they are compared with sonar depth data. Consequently, integration of various drone-based imagery may be applied for producing centimetre resolution bathymetry maps at low cost for small-scale shallow areas.

Download Full-text

Shallow Water Bathymetry Inversion Using Hybrid Multi-band Composites Resulted from Integration of Drone-based RGB and Multispectral Imagery

10.20944/preprints202112.0414.v2 ◽

2022 ◽

Author(s):

Evangelos Alevizos ◽

Athanasios V Argyriou ◽

Dimitris Oikonomou ◽

Dimitrios D Alexakis

Keyword(s):

Low Cost ◽

Visible Spectrum ◽

Small Scale ◽

Multispectral Imagery ◽

Depth Data ◽

Recent Developments ◽

Model Tuning ◽

Inversion Techniques ◽

Camera Sensors ◽

Current Inversion

Download Full-text

RGBD-Inertial Trajectory Estimation and Mapping for Ground Robots

Sensors ◽

10.3390/s19102251 ◽

2019 ◽

Vol 19 (10) ◽

pp. 2251 ◽

Cited By ~ 5

Author(s):

Zeyong Shan ◽

Ruijian Li ◽

Sören Schwertfeger

Keyword(s):

Real Time ◽

Low Cost ◽

Depth Information ◽

Visual Slam ◽

Trajectory Estimation ◽

Depth Data ◽

Localization And Mapping ◽

Mapping System ◽

Camera Sensors ◽

Loop Closing

Using camera sensors for ground robot Simultaneous Localization and Mapping (SLAM) has many benefits over laser-based approaches, such as the low cost and higher robustness. RGBD sensors promise the best of both worlds: dense data from cameras with depth information. This paper proposes to fuse RGBD and IMU data for a visual SLAM system, called VINS-RGBD, that is built upon the open source VINS-Mono software. The paper analyses the VINS approach and highlights the observability problems. Then, we extend the VINS-Mono system to make use of the depth data during the initialization process as well as during the VIO (Visual Inertial Odometry) phase. Furthermore, we integrate a mapping system based on subsampled depth data and octree filtering to achieve real-time mapping, including loop closing. We provide the software as well as datasets for evaluation. Our extensive experiments are performed with hand-held, wheeled and tracked robots in different environments. We show that ORB-SLAM2 fails for our application and see that our VINS-RGBD approach is superior to VINS-Mono.

Download Full-text

Tools of Transformation: Appropriate Technology in U.S. Countercultural Literature

American Studies in Scandinavia ◽

10.22439/asca.v44i2.4917 ◽

2012 ◽

Vol 44 (2) ◽

pp. 75-93

Author(s):

Peter Mortensen

Keyword(s):

Low Cost ◽

Appropriate Technology ◽

Small Scale ◽

Environmental Transformation ◽

Buckminster Fuller ◽

1960S And 1970S ◽

The 1960S ◽

Environmentally Sound ◽

User Friendly ◽

Second Wave

This essay takes its cue from second-wave ecocriticism and from recent scholarly interest in the “appropriate technology” movement that evolved during the 1960s and 1970s in California and elsewhere. “Appropriate technology” (or AT) refers to a loosely-knit group of writers, engineers and designers active in the years around 1970, and more generally to the counterculture’s promotion, development and application of technologies that were small-scale, low-cost, user-friendly, human-empowering and environmentally sound. Focusing on two roughly contemporary but now largely forgotten American texts Sidney Goldfarb’s lyric poem “Solar-Heated-Rhombic-Dodecahedron” (1969) and Gurney Norman’s novel Divine Right’s Trip (1971)—I consider how “hip” literary writers contributed to eco-technological discourse and argue for the 1960s counterculture’s relevance to present-day ecological concerns. Goldfarb’s and Norman’s texts interest me because they conceptualize iconic 1960s technologies—especially the Buckminster Fuller-inspired geodesic dome and the Volkswagen van—not as inherently alienating machines but as tools of profound individual, social and environmental transformation. Synthesizing antimodernist back-to-nature desires with modernist enthusiasm for (certain kinds of) machinery, these texts adumbrate a humanity- and modernity-centered post-wilderness model of environmentalism that resonates with the dilemmas that we face in our increasingly resource-impoverished, rapidly warming and densely populated world.

Download Full-text

Development of a simplified gas ultracleaning process: experiments in biomass residue-based fixed-bed gasification syngas

Biomass Conversion and Biorefinery ◽

10.1007/s13399-021-01680-x ◽

2021 ◽

Author(s):

Christian Frilund ◽

Esa Kurkela ◽

Ilkka Hiltunen

Keyword(s):

Activated Carbons ◽

Low Cost ◽

Fixed Bed ◽

Carbonyl Sulfide ◽

Gas Analysis ◽

Small Scale ◽

Cleaning Process ◽

Medium Temperature ◽

Gas Cleaning ◽

Adsorption Affinity

AbstractFor the realization of small-scale biomass-to-liquid (BTL) processes, low-cost syngas cleaning remains a major obstacle, and for this reason a simplified gas ultracleaning process is being developed. In this study, a low- to medium-temperature final gas cleaning process based on adsorption and organic solvent-free scrubbing methods was coupled to a pilot-scale staged fixed-bed gasification facility including hot filtration and catalytic reforming steps for extended duration gas cleaning tests for the generation of ultraclean syngas. The final gas cleaning process purified syngas from woody and agricultural biomass origin to a degree suitable for catalytic synthesis. The gas contained up to 3000 ppm of ammonia, 1300 ppm of benzene, 200 ppm of hydrogen sulfide, 10 ppm of carbonyl sulfide, and 5 ppm of hydrogen cyanide. Post-run characterization displayed that the accumulation of impurities on the Cu-based deoxygenation catalyst (TOS 105 h) did not occur, demonstrating that effective main impurity removal was achieved in the first two steps: acidic water scrubbing (AWC) and adsorption by activated carbons (AR). In the final test campaign, a comprehensive multipoint gas analysis confirmed that ammonia was fully removed by the scrubbing step, and benzene and H2S were fully removed by the subsequent activated carbon beds. The activated carbons achieved > 90% removal of up to 100 ppm of COS and 5 ppm of HCN in the syngas. These results provide insights into the adsorption affinity of activated carbons in a complex impurity matrix, which would be arduous to replicate in laboratory conditions.

Download Full-text

Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications

Open Chemistry ◽

10.1515/chem-2020-0159 ◽

2020 ◽

Vol 18 (1) ◽

pp. 1148-1166

Author(s):

Ganjar Fadillah ◽

Septian Perwira Yudha ◽

Suresh Sagadevan ◽

Is Fatimah ◽

Oki Muraza

Keyword(s):

Iron Oxide ◽

Water Treatment ◽

Photocatalytic Oxidation ◽

Low Cost ◽

Synthesis Method ◽

Chemical Oxidation ◽

Magnetic Iron Oxide ◽

Oxidation Processes ◽

Recent Developments ◽

Physical And Chemical

AbstractPhysical and chemical methods have been developed for water and wastewater treatments. Adsorption is an attractive method due to its simplicity and low cost, and it has been widely employed in industrial treatment. In advanced schemes, chemical oxidation and photocatalytic oxidation have been recognized as effective methods for wastewater-containing organic compounds. The use of magnetic iron oxide in these methods has received much attention. Magnetic iron oxide nanocomposite adsorbents have been recognized as favorable materials due to their stability, high adsorption capacities, and recoverability, compared to conventional sorbents. Magnetic iron oxide nanocomposites have also been reported to be effective in photocatalytic and chemical oxidation processes. The current review has presented recent developments in techniques using magnetic iron oxide nanocomposites for water treatment applications. The review highlights the synthesis method and compares modifications for adsorbent, photocatalytic oxidation, and chemical oxidation processes. Future prospects for the use of nanocomposites have been presented.

Download Full-text

Revisiting Electrochemical Biosensing in the 21st Century Society for Inflammatory Cytokines Involved in Autoimmune, Neurodegenerative, Cardiac, Viral and Cancer Diseases

Sensors ◽

10.3390/s21010189 ◽

2020 ◽

Vol 21 (1) ◽

pp. 189

Author(s):

Susana Campuzano ◽

Paloma Yáñez-Sedeño ◽

José Manuel Pingarrón

Keyword(s):

Point Of Care ◽

Low Cost ◽

Accurate Determination ◽

Test Time ◽

Electrochemical Biosensing ◽

Recent Developments ◽

Inflammatory Processes ◽

Human Skills ◽

Cancer Diseases

The multifaceted key roles of cytokines in immunity and inflammatory processes have led to a high clinical interest for the determination of these biomolecules to be used as a tool in the diagnosis, prognosis, monitoring and treatment of several diseases of great current relevance (autoimmune, neurodegenerative, cardiac, viral and cancer diseases, hypercholesterolemia and diabetes). Therefore, the rapid and accurate determination of cytokine biomarkers in body fluids, cells and tissues has attracted considerable attention. However, many currently available techniques used for this purpose, although sensitive and selective, require expensive equipment and advanced human skills and do not meet the demands of today’s clinic in terms of test time, simplicity and point-of-care applicability. In the course of ongoing pursuit of new analytical methodologies, electrochemical biosensing is steadily gaining ground as a strategy suitable to develop simple, low-cost methods, with the ability for multiplexed and multiomics determinations in a short time and requiring a small amount of sample. This review article puts forward electrochemical biosensing methods reported in the last five years for the determination of cytokines, summarizes recent developments and trends through a comprehensive discussion of selected strategies, and highlights the challenges to solve in this field. Considering the key role demonstrated in the last years by different materials (with nano or micrometric size and with or without magnetic properties), in the design of analytical performance-enhanced electrochemical biosensing strategies, special attention is paid to the methods exploiting these approaches.

Download Full-text

Understanding Spatial Variability of NO2 in Urban Areas Using Spatial Modelling and Data Fusion Approaches

Atmosphere ◽

10.3390/atmos12020179 ◽

2021 ◽

Vol 12 (2) ◽

pp. 179

Author(s):

Said Munir ◽

Martin Mayfield ◽

Daniel Coca

Keyword(s):

Data Fusion ◽

Spatial Variability ◽

Urban Areas ◽

Road Traffic ◽

Dispersion Model ◽

Low Cost ◽

Spatial Modelling ◽

City Centre ◽

Small Scale ◽

The City

Small-scale spatial variability in NO2 concentrations is analysed with the help of pollution maps. Maps of NO2 estimated by the Airviro dispersion model and land use regression (LUR) model are fused with measured NO2 concentrations from low-cost sensors (LCS), reference sensors and diffusion tubes. In this study, geostatistical universal kriging was employed for fusing (integrating) model estimations with measured NO2 concentrations. The results showed that the data fusion approach was capable of estimating realistic NO2 concentration maps that inherited spatial patterns of the pollutant from the model estimations and adjusted the modelled values using the measured concentrations. Maps produced by the fusion of NO2-LCS with NO2-LUR produced better results, with r-value 0.96 and RMSE 9.09. Data fusion adds value to both measured and estimated concentrations: the measured data are improved by predicting spatiotemporal gaps, whereas the modelled data are improved by constraining them with observed data. Hotspots of NO2 were shown in the city centre, eastern parts of the city towards the motorway (M1) and on some major roads. Air quality standards were exceeded at several locations in Sheffield, where annual mean NO2 levels were higher than 40 µg/m3. Road traffic was considered to be the dominant emission source of NO2 in Sheffield.

Download Full-text

Recent Developments of Antimony-Based Anodes for Sodium- and Potassium-Ion Batteries

Transactions of Tianjin University ◽

10.1007/s12209-021-00304-9 ◽

2021 ◽

Author(s):

Bochao Chen ◽

Ming Liang ◽

Qingzhao Wu ◽

Shan Zhu ◽

Naiqin Zhao ◽

...

Keyword(s):

Structural Characteristics ◽

Low Cost ◽

Potassium Ion ◽

Research Progress ◽

Research Directions ◽

Weak Charge ◽

Recent Developments ◽

High Theoretical Capacity ◽

Further Development ◽

Sodium And Potassium

AbstractThe development of sodium-ion (SIBs) and potassium-ion batteries (PIBs) has increased rapidly because of the abundant resources and cost-effectiveness of Na and K. Antimony (Sb) plays an important role in SIBs and PIBs because of its high theoretical capacity, proper working voltage, and low cost. However, Sb-based anodes have the drawbacks of large volume changes and weak charge transfer during the charge and discharge processes, thus leading to poor cycling and rapid capacity decay. To address such drawbacks, many strategies and a variety of Sb-based materials have been developed in recent years. This review systematically introduces the recent research progress of a variety of Sb-based anodes for SIBs and PIBs from the perspective of composition selection, preparation technologies, structural characteristics, and energy storage behaviors. Moreover, corresponding examples are presented to illustrate the advantages or disadvantages of these anodes. Finally, we summarize the challenges of the development of Sb-based materials for Na/K-ion batteries and propose potential research directions for their further development.

Download Full-text

The Single-Rotor Helicopter with Rigidly-Mounted Blades

Journal of the Royal Aeronautical Society ◽

10.1017/s0001924000062060 ◽

1963 ◽

Vol 67 (634) ◽

pp. 651-663 ◽

Cited By ~ 1

Author(s):

R. R. Heppe

Keyword(s):

General Public ◽

Research Team ◽

Low Cost ◽

Second World War ◽

Public Acceptance ◽

World War ◽

Mass Market ◽

Recent Developments ◽

Second World

For many years, studies of various light aircraft designs have been carried on by the Lockheed-California Company in search of a vehicle that had the potential of truly generating the “air age”—a vehicle which would perform a useful service to many people, in many jobs. Shortly after the Second World War, these studies were directed along the lines of present-day light aeroplanes, but were eventually discarded upon recognition of the limited utility of these vehicles when related to general public acceptance. However, in 1959, spurred by recent developments in VTOL craft, the Lockheed research team again raised the question, “Is it possible today to develop a vehicle of low cost and with sufficient utility to reach the mass market?”

Download Full-text