scholarly journals Adjustment of Transceiver Lever Arm Offset and Sound Speed Bias for GNSS-Acoustic Positioning

2019 ◽  
Vol 11 (13) ◽  
pp. 1606 ◽  
Author(s):  
Guanxu Chen ◽  
Yang Liu ◽  
Yanxiong Liu ◽  
Ziwen Tian ◽  
Jingnan Liu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sound Velocity ◽  
Functional Model ◽  
Systematic Errors ◽  
Vertical Coordinate ◽  
Sea Trial ◽  
Lever Arm ◽  
Main Technique ◽  
The Impact ◽  
Velocity Bias

Global Navigation Satellite System––Acoustic (GNSS-A) positioning is the main technique for seafloor geodetic positioning. A transceiver lever arm offset and sound velocity bias in seawater are the main systematic errors of the GNSS-A positioning technique. Based on data from a sea trial in shallow water, this paper studies the functional model of GNSS-A positioning. The impact of the two systematic errors on seafloor positioning is analysed and corresponding processing methods are proposed. The results show that the offset in the lever arm measurement should be parameterised in the observation equation. Given the high correlation between the vertical lever arm offset and the vertical coordinate of the seafloor station, a sample search method was introduced to fix the vertical offset correction. If the calibration of the sound velocity profiler cannot be ensured, the correction parameter of the sound velocity bias should be solved. According to the refined functional model and corrections, the position of a seafloor station in shallow water can be determined with a precision of better than 1 cm.

scholarly journals Empirical Stochastic Model of Multi-GNSS Measurements

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4566
Author(s):  
Dominik Prochniewicz ◽  
Kinga Wezka ◽  
Joanna Kozuchowska
Keyword(s):  
Stochastic Model ◽  
Density Ratio ◽  
Functional Model ◽  
Optimal Solution ◽  
Global Navigation Satellite Systems ◽  
Unknown Parameters ◽  
Short Baseline ◽  
Stochastic Parameters ◽  
Dependent Model ◽  
The Impact

The stochastic model, together with the functional model, form the mathematical model of observation that enables the estimation of the unknown parameters. In Global Navigation Satellite Systems (GNSS), the stochastic model is an especially important element as it affects not only the accuracy of the positioning model solution, but also the reliability of the carrier-phase ambiguity resolution (AR). In this paper, we study in detail the stochastic modeling problem for Multi-GNSS positioning models, for which the standard approach used so far was to adopt stochastic parameters from the Global Positioning System (GPS). The aim of this work is to develop an individual, empirical stochastic model for each signal and each satellite block for GPS, GLONASS, Galileo and BeiDou systems. The realistic stochastic model is created in the form of a fully populated variance-covariance (VC) matrix that takes into account, in addition to the Carrier-to-Noise density Ratio (C/N0)-dependent variance function, also the cross- and time-correlations between the observations. The weekly measurements from a zero-length and very short baseline are utilized to derive stochastic parameters. The impact on the AR and solution accuracy is analyzed for different positioning scenarios using the modified Kalman Filter. Comparing the positioning results obtained for the created model with respect to the results for the standard elevation-dependent model allows to conclude that the individual empirical stochastic model increases the accuracy of positioning solution and the efficiency of AR. The optimal solution is achieved for four-system Multi-GNSS solution using fully populated empirical model individual for satellite blocks, which provides a 2% increase in the effectiveness of the AR (up to 100%), an increase in the number of solutions with errors below 5 mm by 37% and a reduction in the maximum error by 6 mm compared to the Multi-GNSS solution using the elevation-dependent model with neglected measurements correlations.

scholarly journals Blending and obscuration in weak lensing magnification

2021 ◽  
Author(s):  
E Gaztanaga ◽  
S J Schmidt ◽  
M D Schneider ◽  
J A Tyson
Keyword(s):  
Systematic Errors ◽  
Weak Lensing ◽  
Wide Field ◽  
Photometric Redshifts ◽  
Field Surveys ◽  
Systematic Effects ◽  
The Impact ◽  
Close Pairs ◽  
Mass Profiles

Abstract We test the impact of some systematic errors in weak lensing magnification measurements with the COSMOS 30-band photo-z Survey flux limited to Iauto < 25.0 using correlations of both source galaxy counts and magnitudes. Systematic obscuration effects are measured by comparing counts and magnification correlations. We use the ACS-HST catalogs to identify potential blending objects (close pairs) and perform the magnification analyses with and without blended objects. We find that blending effects start to be important (∼ 0.04 mag obscuration) at angular scales smaller than 0.1 arcmin. Extinction and other systematic obscuration effects can be as large as 0.10 mag (U-band) but are typically smaller than 0.02 mag depending on the band. After applying these corrections, we measure a 3.9σ magnification signal that is consistent for both counts and magnitudes. The corresponding projected mass profiles of galaxies at redshift z ≃ 0.6 (MI ≃ −21) is Σ = 25 ± 6M⊙h3/pc2 at 0.1 Mpc/h, consistent with NFW type profile with M200 ≃ 2 × 1012M⊙h/pc2. Tangential shear and flux-size magnification over the same lenses show similar mass profiles. We conclude that magnification from counts and fluxes using photometric redshifts has the potential to provide complementary weak lensing information in future wide field surveys once we carefully take into account systematic effects, such as obscuration and blending.

scholarly journals Paleoenvironment of the Lower–Middle Cambrian Evaporite Series in the Tarim Basin and Its Impact on the Organic Matter Enrichment of Shallow Water Source Rocks

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 659
Author(s):  
Mingyang Wei ◽  
Zhidong Bao ◽  
Axel Munnecke ◽  
Wei Liu ◽  
G. William M. Harrison ◽  
...  
Keyword(s):  
Organic Matter ◽  
Shallow Water ◽  
Tarim Basin ◽  
Water Environment ◽  
Water Source ◽  
Major Elements ◽  
Source Rocks ◽  
Middle Cambrian ◽  
Sedimentary Environments ◽  
The Impact

Just as in deep-water sedimentary environments, productive source rocks can be developed in an evaporitic platform, where claystones are interbedded with evaporites and carbonates. However, the impact of the paleoenvironment on the organic matter enrichment of shallow water source rocks in an evaporite series has not been well explored. In this study, two wells in the central uplift of the Tarim Basin were systematically sampled and analyzed for a basic geochemical study, including major elements, trace elements, and total organic carbon (TOC), to understand the relationship between TOC and the paleoenvironmental parameters, such as paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity. The results show that the Lower–Middle Cambrian mainly developed in a fluctuating salinity, weak anoxic to anoxic, continuous dry and hot, and proper shallow water environment. The interfingering section of evaporites, carbonates, and claystones of the Awatag Fm. have higher paleoproductivity and higher enrichment of organic matter. Paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity jointly control the organic matter enrichment of shallow water source rocks in the evaporite series. The degree of enrichment of organic matter in shallow water source rocks first increases and then decreases with the increase in paleosalinity. All the samples with high content of organic matter come from the shallower environment of the Awatag Fm.

Quantifying The Impact That Coxswain Behaviour Has on Whole Body Vibration - Simulator Trial

2021 ◽  
Vol 163 (A3) ◽  
Author(s):  
T J Newman
Keyword(s):  
Phase 1 ◽  
Whole Body Vibration ◽  
Whole Body ◽  
Motion Platform ◽  
Body Vibration ◽  
Sea Trial ◽  
Data Driven Approach ◽  
Exposure Levels ◽  
Transit Speed ◽  
The Impact

A common risk to personnel is from Whole Body Vibration (WBV) and shock when transiting at speed in heavy seas, and much research has been done by maritime organisations to reduce this risk and the associated health impacts. It is well known that coxswain ‘driving style’ can radically affect exposure levels for a given sea state and sustained transit speed. A data-driven approach to define what makes a good coxswain from a WBV perspective is currently being developed by the Naval Design Partnering team (NDP). In phase 1, a systematic coxswain behaviour tracking methodology has been developed and demonstrated using a motion platform-based fast craft simulator at MARIN. The performance of several experienced volunteer coxswains from MOD, RNLI and KNRM has been evaluated based on a set pattern of tests. The advantages of using the simulator, over a sea trial, have been demonstrated: it is more repeatable, more controllable, accurate and more accessible. The potential disadvantages of the approach are also discussed with reference to feedback gathered from coxswains. Analysis has shown effective throttle control is much more important than steering to reduce WBV. Several interesting trends in WBV reduction potential have been shown which it is thought, with further validation, could aid mission planning, mission execution and provide data for training autonomous feedback/control algorithms. Further work is required before the findings of this study can be fully exploited. These subsequent phases, which include sea trials, aim to provide validation and further evidence to support the initial findings.

Koncepcja „demokracji zakorzenionej” Wolfganga Merkela w kontekście współczesnego populizmu i kryzysu demokracji

2020 ◽  
Vol 10 (1) ◽  
pp. 57-82
Author(s):  
Katarzyna Guczalska
Keyword(s):  
Civil Society ◽  
Functional Model ◽  
Global Capitalism ◽  
Democratic Institutions ◽  
Political Consequences ◽  
Proper Functioning ◽  
Democratic System ◽  
The Impact

Wolfgang Merkel’s concept of rooted democracy in the context of contemporary populism and the crisis of democracy: The article presents the concept of “rooted democracy” by Wolf‐ gang Merkel, which was presented in the context of the democratic crisis. The German poli‐ tical scientist indicates what democracy is — specifying the proper functioning of the regula‐ tions of the democratic system (regimes). Speaking of the weakness or strength of democracy, we must have a well‐described set of system principles that determine the degree of strength of democracy or its erosion. The above set of principles of the democratic system is thoroughly discussed in the article. In particular, the functional model of civil society is analysed. The text also explores how the crisis of democracy is understood and Merkel’s view of the impact of global capitalism on democratic institutions, which contributes to the transformation of democracy into an oligarchy. The topics discussed in the article also concern alternative, non‐ ‐liberal forms of democracy and populism. The question is whether Merkel’s concept is useful in explaining populism and its political consequences.

scholarly journals Measuring the Impact of Observations on the Predictability of the Kuroshio Extension in a Shallow-Water Model

2012 ◽  
Vol 42 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Werner Kramer ◽  
Henk A. Dijkstra ◽  
Stefano Pierini ◽  
Peter Jan van Leeuwen
Keyword(s):  
Shallow Water ◽  
Particle Filtering ◽  
Predictive Power ◽  
Kuroshio Extension ◽  
Water Model ◽  
Ensemble Prediction ◽  
Shallow Water Model ◽  
One Year ◽  
The Impact ◽  
The Kuroshio

Abstract In this paper, sequential importance sampling is used to assess the impact of observations on an ensemble prediction for the decadal path transitions of the Kuroshio Extension. This particle-filtering approach gives access to the probability density of the state vector, which allows the predictive power—an entropy-based measure—of the ensemble prediction to be determined. The proposed setup makes use of an ensemble that, at each time, samples the climatological probability distribution. Then, in a postprocessing step, the impact of different sets of observations is measured by the increase in predictive power of the ensemble over the climatological signal during one year. The method is applied in an identical-twin experiment for the Kuroshio Extension using a reduced-gravity shallow-water model. This study investigates the impact of assimilating velocity observations from different locations during the elongated and the contracted meandering states of the Kuroshio Extension. Optimal observation locations correspond to regions with strong potential vorticity gradients. For the elongated state the optimal location is in the first meander of the Kuroshio Extension. During the contracted state it is located south of Japan, where the Kuroshio separates from the coast.

scholarly journals WAVETRISK-2.1: an adaptive dynamical core for ocean modelling

2021 ◽  
Author(s):  
Nicholas Keville-Reynolds Kevlahan ◽  
Florian Lemarié
Keyword(s):  
Free Surface ◽  
Shallow Water ◽  
Time Integration ◽  
Ocean Model ◽  
Mesh Adaptivity ◽  
Time Step ◽  
Vertical Coordinate ◽  
Slip Boundary ◽  
Modelling Framework ◽  
Atmosphere Model

Abstract. This paper introduces WAVETRISK-2.1 (i.e. WAVETRISK-OCEAN), an incompressible version of the atmosphere model wavetrisk-1.x with free-surface. This new model is built on the same wavelet-based dynamically adaptive core as wavetrisk, which itself uses DYNANICO's mimetic vector-invariant multilayer rotating shallow water formulation. Both codes use a Lagrangian vertical coordinate with conservative remapping. The ocean variant solves the incompressible multilayer shallow water equations with inhomogeneous density layers. Time integration uses barotropic--baroclinic mode splitting via an semi-implicit free surface formulation, which is about 34–44 times faster than an unsplit explicit time-stepping. The barotropic and baroclinic estimates of the free surface are reconciled at each time step using layer dilation. No slip boundary conditions at coastlines are approximated using volume penalization. The vertical eddy viscosity and diffusivity coefficients are computed from a closure model based on turbulent kinetic energy (TKE). Results are presented for a standard set of ocean model test cases adapted to the sphere (seamount, upwelling and baroclinic turbulence). An innovative feature of wavetrisk-ocean is that it could be coupled easily to the wavetrisk atmosphere model, thus providing a first building block toward an integrated Earth-system model using a consistent modelling framework with dynamic mesh adaptivity and mimetic properties.

scholarly journals Heuristics, biases and traps in managerial decision making

2013 ◽  
Vol 61 (7) ◽  
pp. 2117-2122
Author(s):  
Peter Gál ◽  
Miloš Mrva ◽  
Matej Meško
Keyword(s):  
Decision Making ◽  
Systematic Errors ◽  
Small Samples ◽  
Evidence Based ◽  
Managerial Decision ◽  
Initial Information ◽  
Representativeness Heuristic ◽  
Starting Point ◽  
The World ◽  
The Impact

The aim of the paper is to demonstrate the impact of heuristics, biases and psychological traps on the decision making. Heuristics are unconscious routines people use to cope with the complexity inherent in most decision situations. They serve as mental shortcuts that help people to simplify and structure the information encountered in the world. These heuristics could be quite useful in some situations, while in others they can lead to severe and systematic errors, based on significant deviations from the fundamental principles of statistics, probability and sound judgment. This paper focuses on illustrating the existence of the anchoring, availability, and representativeness heuristics, originally described by Tversky & Kahneman in the early 1970’s. The anchoring heuristic is a tendency to focus on the initial information, estimate or perception (even random or irrelevant number) as a starting point. People tend to give disproportionate weight to the initial information they receive. The availability heuristic explains why highly imaginable or vivid information have a disproportionate effect on people’s decisions. The representativeness heuristic causes that people rely on highly specific scenarios, ignore base rates, draw conclusions based on small samples and neglect scope. Mentioned phenomena are illustrated and supported by evidence based on the statistical analysis of the results of a questionnaire.

Functional tests of the ETCS and rail traffic control systems

2021 ◽  
Vol 133 ◽  
pp. 15-26
Author(s):  
Paweł Drózd ◽  
Adam Rosiński
Keyword(s):  
Traffic Control ◽  
Functional Model ◽  
Field Tests ◽  
Base Layer ◽  
Initial State ◽  
Railway Traffic ◽  
Control Devices ◽  
Traffic Control Devices ◽  
The Cost ◽  
The Impact

The paper presents the issues of railway traffic control devices testing and focuses on European Train Control System (ETCS) devices widely implemented in railways. The functions of the ETCS system, principles of operation are described. The basic telegrams transmitted in the track-to-train relation are listed. The process of designing and verifying the implemented data and what parameters are checked at the stage of field tests using the locomotive is briefly described. The functional model of the SRK devices, including ETCS elements, was presented, and the close relationship between the base layer of the railway traffic control devices and the ETCS was shown. Equipment testing reduces the availability of the rail network, engages staff, and generates costs. A test generation method is presented to minimize the impact. Two indicators are proposed for reducing the set of checks, the cost of checking and the information effectiveness. The cost of checking due to the problematic estimate is generalized, divided into three groups taking into account the difficulty and resource consumption of bringing the devices to the initial state and their operation according to the test. Therefore, the obtained set of checks is suboptimal and ensures complete coverage of the functions with tests, which is essential when testing devices. The tests are carried out using available setting commands and the implementation of tasks - entry and exit routes at the station. The proposed method is universal and can be applied to any railway traffic control device, regardless of the manufacturing technology. It is a non-invasive method in the structure of the tested devices and does not require additional hardware resources.

Requirements Analysis and General Functional Model of Seamless, Citizen-Oriented Service Delivery

2011 ◽  
pp. 2425-2451
Author(s):  
Maria Chiara Pettenati ◽  
Elena Mugellini ◽  
Omar Abou Khaled
Keyword(s):  
Service Delivery ◽  
Functional Model ◽  
Shared Services ◽  
Future Trends ◽  
Government Service ◽  
Services Delivery ◽  
Egovernment Service ◽  
The Impact ◽  
Government Level ◽  
Open Issues

Seamless services provide citizens with what they need to know in a particular topic without having to know which government level or agencies they must contact to get it. Seamless services meet efficiency targets, reduce costs and respond to citizen demands for improved services; they help governments to be more citizen-centered, outcome-oriented, efficient and accountable. This chapter outlines main requirements for the delivery of seamless services and presents a general functional model (e-government service marketplace) for the delivery of shared services to citizens at transaction level (i.e. supporting a complete online handling of a service). The main functionalities of the egovernment service marketplace are analyzed in details. Advantages, disadvantages and the impact of this concept on the three fundamental axes: social, economic and technical are discussed as well. The chapter ends with some insights on future trends and open issues about seamless services delivery and enabling systems.

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