scholarly journals Sound Velocity Estimation of Seabed Sediment Based on Parametric Array Sonar

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.

Non Linear State and Parameters Estimation in Chemical Processes: Analysis and Improvement of Three Estimation Structures Applied to a CSTR

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Héctor Botero ◽  
Hernán Álvarez
Keyword(s):  
Parameter Estimation ◽  
Chemical Process ◽  
Chemical Processes ◽  
The State ◽  
Convergence Speed ◽  
Parameters Estimation ◽  
State Variables ◽  
Input Output ◽  
On Line ◽  
Linear State

This paper proposes a new composite observer capable of estimating the states and unknown (or changing) parameters of a chemical process, using some input-output measurements, the phenomenological based model and other available knowledge about the process. The proposed composite observer contains a classic observer (CO) to estimate the state variables, an observer-based estimator (OBE) to obtain the actual values of the unknown or changing parameters needed to tune the CO, and an asymptotic observer (AO) to estimate the states needed as input to the OBE. The proposed structure was applied to a CSTR model with three state variables. With the proposed structure, the concentration of reactants and other CSTR parameters can be estimated on-line if the reactor and jacket temperatures are known. The procedure for the design of the proposed structure is simple and guarantees observer convergence. In addition, the convergence speed of state and parameter estimation can be adjusted independently.

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

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.

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

2021 ◽  
Vol 2083 (2) ◽  
pp. 022105
Author(s):  
Zhe Yun Li ◽  
Qing Li
Keyword(s):  
Mechanical Properties ◽  
Real Time ◽  
Gas Separation ◽  
Sensor Placement ◽  
Gas Detection ◽  
Shallow Gas ◽  
Seabed Sediment ◽  
Transmission Part ◽  
Seabed Sediments ◽  
Water 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.

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

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.

scholarly journals Experimental Study of Erosion Threshold of Reconstituted Sediments

2011 ◽  
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.

Radar Echo Parameter Estimation Using Sparse Time-Frequency Analysis Method

2014 ◽  
Vol 543-547 ◽  
pp. 2229-2233
Author(s):  
Hao Chen ◽  
Jun Hai Guo
Keyword(s):  
Parameter Estimation ◽  
Frequency Analysis ◽  
Computational Cost ◽  
Velocity Estimation ◽  
Analysis Method ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Mode Decomposition ◽  
Empirical Wavelet Transform ◽  
Adaptive Data Analysis

The echoes of pulse radar from maneuvering targets are amplitude modulation and frequency modulation (AM-FM) signal. At present, the methods of estimating parameters of AM-FM signal are time-frequency analysis method, empirical mode decomposition and empirical wavelet transform based adaptive data analysis methods. This paper takes the idea of intrinsic mode function in guessing the initial phase, and applies the newly developed sparse time-frequency analysis method in AM-FM signal parameter estimation. Simulation results show that the estimating performance of this method in AM-FM signal is good under different SNR and it has low computational cost, and this method is applicable in target acceleration and velocity estimation.

scholarly journals APPLICATION OF BAYESIAN TECHNIQUE FOR PARAMETER ESTIMATION IN A FERMENTATIVE PROCESS

2020 ◽  
Vol 19 (1) ◽  
pp. 105
Author(s):  
C. A. Azevedo ◽  
C. T. Falcón ◽  
D. C. Estumano
Keyword(s):  
Parameter Estimation ◽  
Experimental Tests ◽  
Parameters Estimation ◽  
Operating Conditions ◽  
Biofuel Production ◽  
Experimental Conditions ◽  
Data Set ◽  
Operating Strategies ◽  
Log Normal ◽  
Fermentative Process

In the current world scenario, there has been noted an increase of researches on biofuel production, more specifically bioethanol, produced from biomass, in order to obtain more information to analyze, understand and optimize this fermentative process. The modelling process, which include the determination of a kinetic model and its respective parameters, is a fundamental step in defining operating strategies and understand how the experimental conditions can affect the optimal system operating conditions. The present work employs a bayesian technique to estimate the parameters of a classical kinectic model used by Silva and collaborators (2016), because, unlike the classical techniques, it is possible to take into account the uncertainty of the measurements and the prior knowledge of the parameters can be accounted for in probabilistic terms. In this context, by using simulated measurements, for the parameters estimation it is propose a sensitivity analysis of the parameters model to define the most relevant ones to be estimate and the use of the Monte Carlo Markov Chain method through the Metropolis-Hastings algorithm, evaluating the influence of four types of priori probability distribution of data set: uniform, gaussian, log-normal and Rayleigh. The obtained results showed that the sensibility analysis is an important step on parameter estimation and algorithm used was satisfactory in estimating the parameters of the kinectic model used, demonstrating the possibility of using it as a tool for time and cost reduction in experimental tests.

scholarly journals Parameter Estimation of a Reliability Model of Demand-Caused and Standby-Related Failures of Safety Components Exposed to Degradation by Demand Stress and Ageing That Undergo Imperfect Maintenance

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
S. Martorell ◽  
P. Martorell ◽  
A. I. Sánchez ◽  
R. Mullor ◽  
I. Martón
Keyword(s):  
Parameter Estimation ◽  
Nuclear Power ◽  
Likelihood Estimation ◽  
Real Data ◽  
Parameters Estimation ◽  
Model Parameters ◽  
Reliability Model ◽  
Imperfect Maintenance ◽  
Maintenance Policies

One can find many reliability, availability, and maintainability (RAM) models proposed in the literature. However, such models become more complex day after day, as there is an attempt to capture equipment performance in a more realistic way, such as, explicitly addressing the effect of component ageing and degradation, surveillance activities, and corrective and preventive maintenance policies. Then, there is a need to fit the best model to real data by estimating the model parameters using an appropriate tool. This problem is not easy to solve in some cases since the number of parameters is large and the available data is scarce. This paper considers two main failure models commonly adopted to represent the probability of failure on demand (PFD) of safety equipment: (1) by demand-caused and (2) standby-related failures. It proposes a maximum likelihood estimation (MLE) approach for parameter estimation of a reliability model of demand-caused and standby-related failures of safety components exposed to degradation by demand stress and ageing that undergo imperfect maintenance. The case study considers real failure, test, and maintenance data for a typical motor-operated valve in a nuclear power plant. The results of the parameters estimation and the adoption of the best model are discussed.

Sign in / Sign up

Export Citation Format

Share Document