scholarly journals Lidar Concept of “Guanlan” Mission for Space Oceanography

2020 ◽  
Vol 237 ◽  
pp. 01012
Author(s):  
Songhua Wu ◽  
Weibiao Chen ◽  
Junwu Tang ◽  
Chaofang Zhao ◽  
Ge Chen
Keyword(s):  
Substantial Contribution ◽  
Dual Frequency ◽  
Marine Food Chain ◽  
Subsurface Ocean ◽  
Dynamic Resolution ◽  
Significant Step ◽  
Marine Food ◽  
Step Down ◽  
Spaceborne Radar

Among the various challenges in spaceborne radar observation of the ocean, the following two issues are probably of a higher priority: inadequate dynamic resolution, and ineffective vertical penetration. Two highly anticipated breakthroughs in the coming decade are likely to be associated with radar interferometry and ocean lidar technology, which are expected to make a substantial contribution to a sub-mesoscale-resolving and depth-resolving observation of the ocean. The planned “Guanlan” science mission comprises a dual-frequency (Ku and Ka) interferometric altimetry (IA) and a near-nadir pointing ocean lidar (OL). The spaceborne active OL will ensure a deeper penetration depth and an all-time detection which leads to a layered characterization of the optical properties of the subsurface ocean. The simultaneous functioning of the OL and a dual-frequency (Ku and Ka) interferometric altimetry system will allow an enhanced understanding of contributions of the atmosphere and the air-sea interface which in turn considerably reduce the error budgets of the two sensors. The OL payload is expected to partially reveal the marine food chain and ecosystem with 10-m vertical interval in the euphotic layer, moving a significant step down to the oceanic mixed layer both dynamically and bio-optically.

scholarly journals SMFC as a tool for the removal of hydrocarbons and metals in the marine environment: a concise research update

2021 ◽  
Author(s):  
Edvige Gambino ◽  
Kuppam Chandrasekhar ◽  
Rosa Anna Nastro
Keyword(s):  
Marine Environment ◽  
Microbial Fuel Cells ◽  
Energy Production ◽  
Marine Pollution ◽  
Future Perspectives ◽  
Sediment Remediation ◽  
Marine Food Chain ◽  
Marine Food ◽  
Accumulation Of Pollutants ◽  
Insight Into

AbstractMarine pollution is becoming more and more serious, especially in coastal areas. Because of the sequestration and consequent accumulation of pollutants in sediments (mainly organic compounds and heavy metals), marine environment restoration cannot exempt from effective remediation of sediments themselves. It has been well proven that, after entering into the seawater, these pollutants are biotransformed into their metabolites, which may be more toxic than their parent molecules. Based on their bioavailability and toxic nature, these compounds may accumulate into the living cells of marine organisms. Pollutants bioaccumulation and biomagnification along the marine food chain lead to seafood contamination and human health hazards. Nowadays, different technologies are available for sediment remediation, such as physicochemical, biological, and bioelectrochemical processes. This paper gives an overview of the most recent techniques for marine sediment remediation while presenting sediment-based microbial fuel cells (SMFCs). We discuss the issues, the progress, and future perspectives of SMFC application to the removal of hydrocarbons and metals in the marine environment with concurrent energy production. We give an insight into the possible mechanisms leading to sediment remediation, SMFC energy balance, and future exploitation.

scholarly journals Characterization of Carrier Phase-Based Positioning in Real-World Jamming Conditions

2021 ◽  
Vol 13 (14) ◽  
pp. 2680
Author(s):  
Søren Skaarup Larsen ◽  
Anna B. O. Jensen ◽  
Daniel H. Olesen
Keyword(s):  
Real World ◽  
Carrier Phase ◽  
Reference Station ◽  
Baseline Length ◽  
Dual Frequency ◽  
Positioning Accuracy ◽  
The Impact ◽  
Single Versus ◽  
Selection Of

GNSS signals arriving at receivers at the surface of the Earth are weak and easily susceptible to interference and jamming. In this paper, the impact of jamming on the reference station in carrier phase-based relative baseline solutions is examined. Several scenarios are investigated in order to assess the robustness of carrier phase-based positioning towards jamming. Among others, these scenarios include a varying baseline length, the use of single- versus dual-frequency observations, and the inclusion of the Galileo and GLONASS constellations to a GPS only solution. The investigations are based on observations recorded at physical reference stations in the Danish TAPAS network during actual jamming incidents, in order to realistically evaluate the impact of real-world jamming on carrier phase-based positioning accuracy. The analyses performed show that, while there are benefits of using observations from several frequencies and constellations in positioning solutions, special care must be taken in solution processing. The selection of which GNSS constellations and observations to include, as well as when they are included, is essential, as blindly adding more jamming-affected observations may lead to worse positioning accuracy.

Characterization of an Array-Based Dual-Frequency Transducer for Superharmonic Contrast Imaging

2021 ◽  
pp. 1-1
Author(s):  
Jing Yang ◽  
Emmanuel Cherin ◽  
Jianhua Yin ◽  
Isabel G. Newsome ◽  
Thomas M. Kierski ◽  
...  
Keyword(s):  
Dual Frequency ◽  
Contrast Imaging ◽  
Frequency Transducer

Fabrication and characterization of Na0.5K0.5NbO3-CuNb2O6 lead-free step-down piezoelectric transformers

2011 ◽  
Vol 110 (4) ◽  
pp. 044503 ◽  
Author(s):  
Ming-Ru Yang ◽  
Sheng-Yuan Chu ◽  
I-Hao Chan ◽  
Sheng-Kai Huang
Keyword(s):  
Lead Free ◽  
Step Down ◽  
Fabrication And Characterization ◽  
Piezoelectric Transformers

Optical and mechanical characterization of ultrananocrystalline diamond films prepared in dual frequency discharges

2010 ◽  
Vol 204 (12-13) ◽  
pp. 1997-2001 ◽  
Author(s):  
Monika Karásková ◽  
Lenka Zajíčková ◽  
Vilma Buršíková ◽  
Daniel Franta ◽  
David Nečas ◽  
...  
Keyword(s):  
Mechanical Characterization ◽  
Diamond Films ◽  
Dual Frequency ◽  
Ultrananocrystalline Diamond

scholarly journals Uptake and trophic changes in polybrominated diphenyl ethers in the benthic marine food chain in southwestern British Columbia, Canada

FACETS ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 20-51
Author(s):  
Brenda Burd ◽  
Chris Lowe ◽  
Carmen Morales-„Caselles ◽  
Marie Noel ◽  
Peter Ross ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Polybrominated Diphenyl Ethers ◽  
Dry Weight ◽  
Trophic Levels ◽  
Marine Food Chain ◽  
Deposit Feeders ◽  
Diphenyl Ethers ◽  
Bottom Fish ◽  
Harbour Sediment ◽  
Marine Food

We examined the physical and geochemical effects of sediment on the uptake of polybrominated diphenyl ethers (PBDEs) into marine sediment feeders and their transfer to higher trophic fauna. Sediment PBDEs increased with % total organic carbon (%TOC), organic carbon (OC) flux and grain size (%fines). Tissue PBDE variance was best explained ( R2 = 0.70) by sediment acid volatile sulfides (AVS), PBDEs, and organic lability and input, with the highest values near wastewater outfalls. Dry weight tissue/sediment PBDEs declined with increasing sediment PBDEs, resulting in tissue dilution (ratio <1) at >10 000 pg/g in harbours. Ratios also decreased with increasing %fines, resulting in regional differences. These patterns imply that high levels of fines and high sediment concentrations make PBDEs less bioavailable. Dry weight PBDEs increased >100× between background deposit feeders and predators (polychaetes, crabs, bottom fish, seal), but lipid normalized PBDEs barely increased (<1.3%), suggesting remarkably high uptake in low-lipid sediment feeders, and that PBDEs don’t accumulate at higher trophic levels, but lipid content does. Filter feeders had lower lipid-normalized PBDEs than deposit feeders, highlighting the importance of food resources in higher trophic fauna for bioaccumulation. The most profound congener change occurred with sediment uptake, with nona/deca-BDEs declining and tetra-hexa-BDEs increasing. Harbour sediment feeders had more deca-BDEs than other samples, suggesting PBDEs mostly pass unmodifed through them. Deca-BDEs persist patchily in all tissues, reflecting variable dependence on sediment/pelagic food.

scholarly journals Acoustic characterization of seafloor habitats on the western continental shelf of India

2007 ◽  
Vol 64 (3) ◽  
pp. 551-558 ◽  
Author(s):  
Bishwajit Chakraborty ◽  
Vasudev Mahale ◽  
Gajanan Navelkar ◽  
B. Ramalingeswara Rao ◽  
R. G. Prabhudesai ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Dual Frequency ◽  
Scattering Process ◽  
Backscatter Signal ◽  
Sediment Volume ◽  
Interface Scattering ◽  
Acoustic Characterization ◽  
Power Law Exponent ◽  
Different Grain Size

Abstract Chakraborty, B., Mahale, V., Navelkar, G., Rao, B. R., Prabhudesai, R. G., Ingole, B., and Janakirinam, G. 2007. Acoustic characterization of seafloor habitats on the western continental shelf of India. – ICES Journal of Marine Science, 64: 551–558. This is a study of the interaction effects of the dual-frequency (210 and 33 kHz) backscatter signal with seafloor sediment and benthic biota along a transect in water 27–83 m deep offshore of the Goa region of India's central west coast. Estimation of the power-law exponent using seafloor topographic data provided equivalent values even when using dual high-frequency systems for different grain-size sediments. Backscatter signals corrected from system-related gain, etc., reveal better correlations with sedimentary and benthic parameters than the estimated coherence parameters (using echo peaks). Statistically, correlations are significant for the 210 kHz backscatter signal with sand and calcium carbonate (CaCO3) sediment content. Also, correlations are higher for macrobenthic biomass (wet weight) and population density with a 210 kHz backscatter strength, emphasizing the dominant seawater–seafloor interface scattering process. For 33 kHz backscatter strength, the absence of such correlations indicates a different scattering process, i.e. dominant sediment volume scattering attributable to the comparatively lower signal attenuation. Additionally, to validate the results, the backscatter signals from other locations in the vicinity of this transect were considered.

scholarly journals An Initial Assessment of the Surface Reference Technique Applied to Data from the Dual-Frequency Precipitation Radar (DPR) on the GPM Satellite

2015 ◽  
Vol 32 (12) ◽  
pp. 2281-2296 ◽  
Author(s):  
Robert Meneghini ◽  
Hyokyung Kim ◽  
Liang Liao ◽  
Jeffrey A. Jones ◽  
John M. Kwiatkowski
Keyword(s):  
Cross Section ◽  
Radar Data ◽  
Single Frequency ◽  
Initial Assessment ◽  
Dual Frequency ◽  
Precipitation Radar ◽  
Frequency Method ◽  
Ka Band ◽  
Spaceborne Radar ◽  
Ku Band

AbstractIt has long been recognized that path-integrated attenuation (PIA) can be used to improve precipitation estimates from high-frequency weather radar data. One approach that provides an estimate of this quantity from airborne or spaceborne radar data is the surface reference technique (SRT), which uses measurements of the surface cross section in the presence and absence of precipitation. Measurements from the dual-frequency precipitation radar (DPR) on the Global Precipitation Measurement (GPM) satellite afford the first opportunity to test the method for spaceborne radar data at Ka band as well as for the Ku-band–Ka-band combination.The study begins by reviewing the basis of the single- and dual-frequency SRT. As the performance of the method is closely tied to the behavior of the normalized radar cross section (NRCS or σ0) of the surface, the statistics of σ0 derived from DPR measurements are given as a function of incidence angle and frequency for ocean and land backgrounds over a 1-month period. Several independent estimates of the PIA, formed by means of different surface reference datasets, can be used to test the consistency of the method since, in the absence of error, the estimates should be identical. Along with theoretical considerations, the comparisons provide an initial assessment of the performance of the single- and dual-frequency SRT for the DPR. The study finds that the dual-frequency SRT can provide improvement in the accuracy of path attenuation estimates relative to the single-frequency method, particularly at Ku band.

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