Comprehensive detection device and physical testing for mechanical properties of seabed sediments and shallow gas

Abstract In this paper, a comprehensive detection device for the mechanical properties of seabed sediments and shallow gas is designed, which is mainly composed of the seabed sediment mechanical properties detection part, the shallow gas detection part and the ultrasonic wireless transmission part. The mud water gas separation structure of the shallow gas detection part separates the shallow gas from the mud water, and then the methane concentration in the shallow gas is measured by the non-dispersive infrared methane sensor, which realizes the collection of the submarine shallow gas and the automatic real-time monitoring of the concentration. The measurement of the mechanical properties of seabed sediments realizes the real-time measurement of the three parameters of cone resistance, sidewall friction and pore water pressure, which characterize the mechanical properties of seabed sediments, through strain-sensitive elements. The ultrasonic wireless data transmission part is mainly for the data detected by the mechanical properties of the seabed sediments to be wirelessly transmitted to the sensor placement room through the ultrasonic transducer across the mud-water-gas separation structure. Finally, the data measured by the two parts are transmitted to the mother ship through the cable located in the sensor placement room. The experimental results show that it has the ability to comprehensively detect the mechanical properties of seabed sediments and shallow gas, and has strong operability.

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A poly(arylene ether sulfone) hybrid membrane using titanium dioxide nanoparticles as the filler

High Performance Polymers ◽

10.1177/0954008315626990 ◽

2016 ◽

Vol 29 (1) ◽

pp. 26-35 ◽

Cited By ~ 10

Author(s):

Yunwu Yu ◽

Wenhao Pan ◽

Xiaoman Guo ◽

Lili Gao ◽

Yaxin Gu ◽

...

Keyword(s):

Mechanical Properties ◽

Titanium Dioxide ◽

Gas Separation ◽

Proton Nuclear Magnetic Resonance ◽

Separation Performance ◽

Hydroxyl Groups ◽

Hybrid Membranes ◽

Permeability Coefficients ◽

Arylene Ether ◽

The Matrix

Poly(arylene ether sulfone) (PES)–titanium dioxide (TiO2) hybrid membranes were prepared via solution blending method using TiO2 nanoparticles as inorganic filler. The chemical structure and thermal stability of the matrix polymer were characterized by proton nuclear magnetic resonance, Fourier transform infrared, differential scanning calorimetry, and thermogravimetric analysis. The crystal structure, morphology, mechanical properties, and gas separation performance of hybrid membranes were characterized in detail. As shown in scanning electron microscopic images, TiO2 nanoparticles dispersed homogeneously in the matrix. Although the mechanical properties of hybrid membranes decreased certainly compared to the pure PES membranes, they are strong enough for gas separation in this study. All gas permeability coefficients of PES-TiO2 hybrid membranes were higher than pure PES membranes, attributed to the nanogap caused by TiO2 nanoparticles, for instance, oxygen and nitrogen permeability coefficients of Hybrid-3 (consists of PES with 4-amino-phenyl pendant group and hexafluoroisopropyl (Am-PES)-20 and TiO2 nanoparticles, 5 wt%) increased from 2.57 and 0.33 to 5.88 and 0.63, respectively. In addition, the separation factor increased at the same time attributed to the stimulative transfer effect caused by the interaction of hydroxyl groups on the TiO2 nanoparticle and polar carbon dioxide molecules.

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Sound Velocity Estimation of Seabed Sediment Based on Parametric Array Sonar

Mathematical Problems in Engineering ◽

10.1155/2020/9810215 ◽

2020 ◽

Vol 2020 ◽

pp. 1-6

Author(s):

Jingxin Ma ◽

Haisen Li ◽

Jianjun Zhu ◽

Baowei Chen

Keyword(s):

Parameter Estimation ◽

Acoustic Parameter ◽

Velocity Estimation ◽

Parameters Estimation ◽

Real Field ◽

Sound Waves ◽

Sediment Thickness ◽

Seafloor Topography ◽

Seabed Sediment ◽

Seabed Sediments

Backscattered sound waves of seabed sediments are important information carriers in seafloor detection and acoustic characteristic parameters inversion. Most of the existing methods for estimating geoacoustic parameters are based on multiangle seabed backscattered signal processing and suitable for flat seafloor conditions with uniform sediment thickness. This usually deviates from the real field conditions and affects the accuracy of parameter estimation. In this paper, the sound ray propagation theory is studied and analysed under the condition of sloping seabed and uneven sediment thickness. Based on the phased parameter array sonar system, a method of acoustic parameters estimation of the sediment under inclined seabed conditions is proposed. The simulation results show that the new method shows good adaptability to different inclination angles of the seabed and solves the problem of accuracy of acoustic parameter estimation of the inclined seabed sediments. The model will greatly reduce the seafloor topography requirements in the sediment acoustic parameter inversion, such as velocity, layer thickness, and acoustic impedance.

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Highly gas permselective polyetherketone hollow fibre membranes using aqueous sulfuric acid solution as coagulant

e-Polymers ◽

10.1515/epoly.2007.7.1.884 ◽

2007 ◽

Vol 7 (1) ◽

Author(s):

Jiping Yang ◽

Philip J Brown

Keyword(s):

Mechanical Properties ◽

Sulfuric Acid ◽

Acid Solution ◽

Gas Separation ◽

Sulfuric Acid Solution ◽

Hollow Fibre ◽

Injection Rate ◽

Fluid Injection ◽

Aqueous Sulfuric Acid ◽

Membrane Morphology

AbstractHollow fibre membranes with more sponge-like morphology and improved gas permeation performance were spun from 20% polyetherketone (PEK) /sulfuric acid (H2SO4) dope solution with aqueous sulfuric acid solution as coagulant using dry-jet wet spinning process. The membrane morphology, mechanical properties and gas separation performance (hydrogen, methane and carbon dioxide) of as-spun PEK hollow fibres have been measured using SEM, Instron and gas test rig. Better cross section structures and mechanical properties in as-spun PEK hollow fibres were observed when aqueous sulfuric acid solution replaced water as coagulant (internal and external). The hydrogen/methane selectivity of up to 40 and hydrogen permeation rate of 3.65 GPU obtained in PEK hollow fibre membranes using 30% sulfuric acid solution as internal and external coagulant simultaneously at the bore fluid injection rate of 30 ml/h are higher than those reported in literatures. Furthermore the effects of bore fluid injection rate and various coagulants on the membrane morphology, mechanical properties and gas separation properties were investigated, as well.

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The potential for mobile demersal fishing to reduce carbon storage and sequestration in seabed sediments

10.1101/2021.07.07.450307 ◽

2021 ◽

Author(s):

Graham Epstein ◽

Julie P Hawkins ◽

Catrin R Norris ◽

Callum M Roberts

Keyword(s):

Sediment Resuspension ◽

Order Estimate ◽

Sediment Type ◽

Seabed Sediment ◽

Flocculent Material ◽

Sediment Carbon ◽

Carbon Stores ◽

Seabed Sediments ◽

Fish And Shellfish ◽

The Impact

Subtidal marine sediments are one of the planet's primary carbon stores and strongly influence the oceanic sink for atmospheric CO2. By far the most pervasive human activity occurring on the seabed is bottom trawling and dredging for fish and shellfish. A global first-order estimate suggested mobile demersal fishing activities may cause 160-400 Mt of organic carbon (OC) to be remineralised annually from seabed sediment carbon stores. There are, however, many uncertainties in this calculation. Here, we discuss the potential drivers of change in seabed OC stores due to mobile demersal fishing activities and conduct a systematic review, synthesising studies where this interaction has been directly investigated. Mobile demersal fishing would be expected to reduce OC in seabed stores, albeit with site-specific variability. Reductions would occur due to lower production of flora and fauna, the loss of fine flocculent material, increased sediment resuspension, mixing and transport, and increased oxygen exposure. This would be offset to some extent by reduced faunal bioturbation and respiration, increased off-shelf transport and increases in primary production from the resuspension of nutrients. Studies which directly investigated the impact of demersal fishing on OC stocks had mixed results. A finding of no significant effect was reported in 51% of 59 experimental contrasts; 41% reported lower OC due to fishing activities, with 8% reporting higher OC. In relation to remineralisation rates within the seabed, 14 experimental contrasts reported that demersal fishing activities decreased remineralisation, with four reporting higher remineralisation rates. The direction of effects was related to sediment type, impact duration, study design and local hydrography. More evidence is urgently needed to accurately quantify the impact of anthropogenic physical disturbance on seabed carbon in different environmental settings, and incorporate full evidence-based carbon considerations into global seabed management.

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Data heterogeneity and oldness, two difficulties to overcome for the world seabed sediment mapping

Proceedings of the ICA ◽

10.5194/ica-proc-4-35-2021 ◽

2021 ◽

Vol 4 ◽

pp. 1-7

Author(s):

Thierry Garlan ◽

Isabelle Gabelotaud ◽

Elodie Marchès ◽

Edith Le Borgne ◽

Sylvain Lucas

Keyword(s):

Global Scale ◽

Single Product ◽

Seabed Sediment ◽

Bathymetric Data ◽

The World ◽

Data Heterogeneity ◽

Sediment Data ◽

The University ◽

Seabed Sediments

Abstract. A global seabed sediment map has been developed since 1995 to provide a necessary tool for different needs. This project is not completely original since it had already been done in 1912 when the French hydrographic Office and the University of Nancy produced sedimentary maps of the European and North American coasts. Seabed sediments is one of the last geographical domains which can’t benefit of satellite data. Without this contribution, sediment maps need to use very old data mixed with the new ones to be able to reach the goal of a global map. In general, sediment maps are made with the latest available techniques and are replaced after a few decades, thus generating new cartographic works as if all the previous efforts had become useless. Such approach underestimates the quality of past works and prevents to have maps covering large areas. The present work suggests to standardize all kind of sedimentary data from different periods and from very different acquisition systems and integrate them into a single product. This process has already been done for bathymetric data of marine charts, we discuss in this article of the application of this method at a global scale for sediment data.

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Experimental Study of Erosion Threshold of Reconstituted Sediments

Volume 7: CFD and VIV; Offshore Geotechnics ◽

10.1115/omae2011-50067 ◽

2011 ◽

Cited By ~ 2

Author(s):

Zhihui Ye ◽

Liang Cheng ◽

Zhipeng Zang

Keyword(s):

Shear Stress ◽

Steady Increase ◽

Initial Increase ◽

Threshold Condition ◽

Seabed Sediment ◽

Erosion Threshold ◽

Sediment Types ◽

Weight Content ◽

Testing Facility ◽

Seabed Sediments

Understanding of fundamental erosion characteristics of seabed sediments on which pipelines and other structures are founded is critical for the design of these facilities. The erosion threshold condition of cohesive sediments is not well understood because of the complexity and variability of natural sediments. Most of the existing methods for evaluating the erosion behaviours of seabed sediment are often applicable to the certain particular sediment types and test conditions. There appears to be a need for more research efforts in this area. In present research, the threshold of motion of four moderately consolidated mixtures was tested under unidirectional currents using a testing facility. Three threshold shear stress increase modes were observed, including initial increase mode, steady increase mode and equilibrium mode as mass content of mud Pm increases. A dimensionless threshold shear stress τ* is proposed to quantify the shear strength of these reconstituted mixtures, coupled with variation of coarse particle size. Finally, a predicting model is proposed to illustrate the trend of erosion threshold of the four mixtures as a function of mud weight content. Further understanding of erosion threshold can rely on the various consolidation conditions and different coarse and fine materials inputted in the mixture.

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