Concentration and velocity measurements in experimental turbidity currents 

2021 ◽  
Author(s):  
Patricia Buffon ◽  
Daniel Valero ◽  
Wim Uijttewaal ◽  
Mário Franca
Keyword(s):  
Initial Conditions ◽  
Unsteady Flows ◽  
Turbidity Currents ◽  
Ministry Of Education ◽  
Velocity Measurements ◽  
Statistical Tools ◽  
Measure Concentration ◽  
Acoustic Techniques ◽  
The Mean ◽  
Education In Brazil

<p>Turbidity currents are in the range of highly sediment concentrated flows, challenging traditional (i.e. optical and acoustic) techniques that aim to measure concentration and velocity quantities. In typical laboratory conditions, difficulties increase in the presence of highly non-uniform and unsteady flows. However, the measurement of those quantities along with a longitudinal profile is necessary to quantify and depict key mechanisms of mass and momentum transport, related to the mean and turbulent flow fields. The possible solutions often require prohibitive costs or resources. In this work, visual, acoustic, electrical, and statistical tools are tested. The aim of these tests is to find appropriate techniques and strategies for measuring concentration and velocity quantities in the broader research scope involving turbidity currents triggered by a 2D water jet. The outcomes will be applied in the quantification of turbidity currents with various boundary and initial conditions in a flume 4 m long, 2 m deep, and 22 cm wide. Additionally, the findings can potentially be transferred to other laboratory applications involving turbidity currents or other types of sediment-laden flows.</p><p>Acknowledgements: CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, a Foundation within the Ministry of Education in Brazil), grant number 88881.174820/2018-01.</p>

scholarly journals Extended and Unscented Kalman Filtering Applied to a Flexible-Joint Robot with Jerk Estimation

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Mohammad Ali Badamchizadeh ◽  
Iraj Hassanzadeh ◽  
Mehdi Abedinpour Fallah
Keyword(s):  
Initial Conditions ◽  
Covariance Matrices ◽  
Flexible Joints ◽  
Velocity Measurements ◽  
Lagrange Equations ◽  
Robust Nonlinear Control ◽  
Flexible Joint ◽  
Flexible Joint Robots ◽  
Simulation Results

Robust nonlinear control of flexible-joint robots requires that the link position, velocity, acceleration, and jerk be available. In this paper, we derive the dynamic model of a nonlinear flexible-joint robot based on the governing Euler-Lagrange equations and propose extended and unscented Kalman filters to estimate the link acceleration and jerk from position and velocity measurements. Both observers are designed for the same model and run with the same covariance matrices under the same initial conditions. A five-bar linkage robot with revolute flexible joints is considered as a case study. Simulation results verify the effectiveness of the proposed filters.

scholarly journals Mass determination of the 1:3:5 near-resonant planets transiting GJ 9827 (K2-135)

2018 ◽  
Vol 618 ◽  
pp. A116 ◽  
Author(s):  
J. Prieto-Arranz ◽  
E. Palle ◽  
D. Gandolfi ◽  
O. Barragán ◽  
E. W. Guenther ◽  
...  
Keyword(s):  
Planetary System ◽  
Initial Conditions ◽  
Dynamical Evolution ◽  
Space Mission ◽  
Mass Determination ◽  
Velocity Measurements ◽  
Orbital Periods ◽  
The Masses ◽  
Better Than

Context. Multiplanet systems are excellent laboratories to test planet formation models as all planets are formed under the same initial conditions. In this context, systems transiting bright stars can play a key role, since planetary masses, radii, and bulk densities can be measured. Aims. GJ 9827 (K2-135) has recently been found to host a tightly packed system consisting of three transiting small planets whose orbital periods of 1.2, 3.6, and 6.2 days are near the 1:3:5 ratio. GJ 9827 hosts the nearest planetary system (~30 pc) detected by NASA’s Kepler or K2 space mission. Its brightness (V = 10.35 mag) makes the star an ideal target for detailed studies of the properties of its planets. Methods. Combining the K2 photometry with high-precision radial-velocity measurements gathered with the FIES, HARPS, and HARPS-N spectrographs we revised the system parameters and derive the masses of the three planets. Results. We find that GJ 9827 b has a mass of Mb = 3.69−0.46+0.48 M⊕ and a radius of Rb = 1.58−0.13+0.14 R⊕, yielding a mean density of ρb = 5.11−1.27+1.74 g cm−3. GJ 9827 c has a mass of Mc = 1.45−0.57+0.58 M⊕, radius of Rc = 1.24−0.11+0.11 R⊕, and a mean density of ρc = 4.13−1.77+2.31 g cm−3. For GJ 9827 d, we derive Md = 1.45−0.57+0.58 M⊕, Rd = 1.24−0.11+0.11 R⊕, and ρd = 1.51−0.53+0.71 g cm−3. Conclusions. GJ 9827 is one of the few known transiting planetary systems for which the masses of all planets have been determined with a precision better than 30%. This system is particularly interesting because all three planets are close to the limit between super-Earths and sub-Neptunes. The planetary bulk compositions are compatible with a scenario where all three planets formed with similar core and atmosphere compositions, and we speculate that while GJ 9827 b and GJ 9827 c lost their atmospheric envelopes, GJ 9827 d maintained its primordial atmosphere, owing to the much lower stellarirradiation. This makes GJ 9827 one of the very few systems where the dynamical evolution and the atmosphericescape can be studied in detail for all planets, helping us to understand how compact systems form and evolve.

scholarly journals Application of the adjoint approach to optimise the initial conditions of a turbidity current

2016 ◽  
Author(s):  
Samuel D. Parkinson ◽  
Simon W. Funke ◽  
Jon Hill ◽  
Matthew D. Piggott ◽  
Peter A. Allison
Keyword(s):  
Initial Conditions ◽  
Current Model ◽  
Deep Ocean ◽  
Turbidity Current ◽  
Significant Advance ◽  
Turbidity Currents ◽  
General Behaviour ◽  
Depositional Processes ◽  
Sediment Deposits ◽  
Adjoint Approach

Abstract. Turbidity currents are one of the main drivers for sediment transport from the continental shelf to the deep ocean. The resulting sediment deposits can reach hundreds of kilometres into the ocean. Computer models that simulate turbidity currents and the resulting sediment deposit can help to understand their general behaviour. However, in order to recreate real-world scenarios, the challenge is to find the turbidity current parameters that reproduce the observations of sediment deposits. This paper demonstrates a solution to the inverse sediment transportation problem: for a known sedimentary deposit, the developed model reconstructs details about the turbidity current that produced these deposits. The reconstruction is constrained here by a shallow water sediment-laden density current model, which is discretised by the finite element method and an adaptive time-stepping scheme. The model is differentiated using the adjoint approach and an efficient gradient-based optimisation method is applied to identify turbidity parameters which minimise the misfit between modelled and observed field sediment deposits. The capabilities of this approach are demonstrated using measurements taken in the Miocene-age Marnoso Arenacea Formation (Italy). We find that whilst the model cannot match the deposit exactly due to limitations in the physical processes simulated, it provides valuable insights into the depositional processes and represents a significant advance in our toolset for interpreting turbidity current deposits.

scholarly journals Evaluation of constructive teaching skills among science teachers in the intermediate stage: تقويم مهارات التدريس البنائي لدى معلمي العلوم في المرحلة المتوسطة

2017 ◽  
Vol 1 (6) ◽  
Author(s):  
Abdullah bin Zaher Al - Shihri ◽  
Tammam Ismail Tammam
Keyword(s):  
Science Teachers ◽  
Intermediate Stage ◽  
Teaching Skills ◽  
Ministry Of Education ◽  
Graduate Studies ◽  
Training Courses ◽  
The Subject ◽  
Descriptive Approach ◽  
The Mean ◽  
Constructive Teaching

The research aims to study the teaching skills and evaluate the teaching skills of science teachers, and test significance of differences between the mean degree of practice according to the variables: gender, experience, educational qualification, and stage educational, and to achieve these objectives were applied a questionnaire consisting of (31) paragraph, to a sample Of (45) are teachers of science in the intermediate stage of the Ministry of Education and Mjardp. The researcher also followed the descriptive approach. The results indicated that the degree of science teachers and her teachers to teach constructivist was medium, and appeared statistically significant scientific qualification variable differences, for the benefit of graduate studies. The study recommended training courses for science teachers, to familiarize them with the skills of teaching constructivist, and trained to teach these skills to have procedures and guide administrators science with a list of skills (the subject of the study), during the supervision of the education in the schools of the intermediate stage and directing the attention of the authors and curriculum developers to take into account the good fundamentals in the article To provide learners with a leading to the development of scientific concepts in general.

scholarly journals A modified fluctuation test for elucidating drug resistance in microbial and cancer cells

2020 ◽  
Author(s):  
Pavol Bokes ◽  
Abhyudai Singh
Keyword(s):  
Drug Resistance ◽  
Cancer Cells ◽  
Colony Size ◽  
Random Number ◽  
Initial Conditions ◽  
Fano Factor ◽  
Persister Cells ◽  
Efficient Treatment ◽  
Fluctuation Test ◽  
The Mean

AbstractClonal populations of microbial and cancer cells are often driven into a drug-tolerant persister state in response to drug therapy, and these persisters can subsequently adapt to the new drug environment via genetic and epigenetic mechanisms. Estimating the frequency with which drug-tolerance states arise, and its transition to drug-resistance, is critical for designing efficient treatment schedules. Here we study a stochastic model of cell proliferation where drug-tolerant persister cells transform into a drug-resistant state with a certain adaptation rate, and the resistant cells can then proliferate in the presence of the drug. Assuming a random number of persisters to begin with, we derive an exact analytical expression for the statistical moments and the distribution of the total cell count (i.e., colony size) over time. Interestingly, for Poisson initial conditions the noise in the colony size (as quantified by the Fano factor) becomes independent of the initial condition and only depends on the adaptation rate. Thus, experimentally quantifying the fluctuations in the colony sizes provides an estimate of the adaptation rate, which then can be used to infer the starting persister numbers from the mean colony size. Overall, our analysis introduces a modification of the classical Luria–Delbrück experiment, also called the “Fluctuation Test”, providing a valuable tool to quantify the emergence of drug resistance in cell populations.

scholarly journals Особенности конкуренции спиновой и псевдоспиновой подсистем в модельном купрате

2019 ◽  
Vol 61 (5) ◽  
pp. 822
Author(s):  
Ю.Д. Панов ◽  
В.А. Улитко ◽  
К.С. Будрин ◽  
Д.Н. Ясинская ◽  
А.А. Чиков
Keyword(s):  
Russian Federation ◽  
Mean Field ◽  
Charge Ordering ◽  
Ministry Of Education ◽  
Quantum Liquids ◽  
Magnetic Spin ◽  
Strong Exchange ◽  
The Russian Federation ◽  
The Mean ◽  
The Government

We consider the competition of magnetic and charge ordering in model cuprate within the framework of the simplified static 2D spin-pseudospin model. This model is equivalent to the 2D dilute antiferromagnetic (AFM) Ising model with charged impurities. We present the mean-field results for the system under study and make a brief comparison with classicalMonte Carlo (MC) calculations. Numerical simulations show that the cases of strong exchange and strong charge correlation differ qualitatively. For a strong exchange, the AFM phase is unstable with respect to the phase separation (PS) into the pseudospin (charge) and magnetic (spin) subsystems, which behave like immiscible quantum liquids. An analytical expression was obtained for the PS temperature. The research was supported by the Government of the Russian Federation, Program 02.A03.21.0006 and by the Ministry of Education and Science of the Russian Federation, projects Nos. 2277 and 5719, and RFBR N 18-32-0083718.

Critical layers in accelerating two-layer flows

1988 ◽  
Vol 197 ◽  
pp. 429-451 ◽  
Author(s):  
Donald B. Altman
Keyword(s):  
Laboratory Experiments ◽  
Single Mode ◽  
Shear Instability ◽  
Mean Flow ◽  
Velocity Measurements ◽  
Interfacial Wave ◽  
Flow Acceleration ◽  
Critical Layers ◽  
The Mean ◽  
Processing Software

A series of laboratory experiments on accelerating two-layer shear flows over topography is described. The mean flow reverses at the interface of the layers, forcing a critical layer to occur there. It is found that for a sufficiently thin interface, a slowly growing recirculating region, the ‘acceleration rotor’, develops on the interfacial wave at mean-flow Richardson numbers of O(0.5). This, in turn, can induce a secondary dynamical shear instability on the trailing edge of the wave. A single-mode, linear, two-layer numerical model reproduces many features of the acceleration rotor if mean-flow acceleration and bottom forcing are included. Velocity measurements are obtained from photographs using image processing software developed for the automated reading of particle-streak photographs. Typical results are shown.

scholarly journals The empirical period-radius relation for pulsating stars: a synthesis based on photometric and radial velocity measurements

1986 ◽  
Vol 118 ◽  
pp. 273-274
Author(s):  
G. Burki
Keyword(s):  
Radial Velocity ◽  
Stellar Evolution ◽  
Variable Stars ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
Pulsating Stars ◽  
Powerful Test ◽  
The Mean

The relation existing between the radius and the period for the pulsating stars of a given class constitutes a powerful test for the theory of stellar evolution and for the identification of the pulsation modes. In recent years, several authors have determined the mean radius of a lot of pulsating stars of various classes by applying the Baade-Wesselink method. Fig. 1 presents the resulting general logP - logR diagram grouping these determinations. The sources for the radii are given by Burki and Meylan (1986). The variable stars in known binaries have been excluded since the presence of a companion biases the radius calculation (Burki, 1984). The determinations marked by arrows are based on the radial velocities by CORAVEL (1m telescope at the Haute-Provence Observatory, France) or/and on the photometry in the Geneva system (40cm and 70cm telescopes at La Silla Observatory, Chile).

scholarly journals Farmers’ perception of adoption of postharvest technologies of selected food crops in rivers state, Nigeria

2018 ◽  
Vol 7 (2) ◽  
pp. 22-26 ◽  
Author(s):  
MK Elemasho ◽  
SDY Alfred ◽  
CC Aneke ◽  
AJC Chugali ◽  
O Ajiboye
Keyword(s):  
Food Crops ◽  
Positive Perception ◽  
Statistical Tools ◽  
Post Harvest ◽  
Positive Statements ◽  
The Mean ◽  
High Level ◽  
Adoption Level ◽  
Rivers State ◽  
Structured Questionnaire

The study was conducted to determine the perception of food crops farmers on adoption of selected post-harvest technologies in Rivers State, Nigeria. A multistage snow-ball, procedure was used to sample 135 selected food crops farmers in the State. A well, structured questionnaire was used to obtain information from the respondents using both descriptive and inferential statistical tools. The result revealed that, majority (85.9%) of the respondents, were females while 84.4% of the respondents were married. The mean age of the respondent was 41.0 years and highly experienced in food crops production with mean of 15.9 years experience. Majority of the respondents (77%) attended primary school. The level of food crops farmers’ perception on adoption of post-harvest technologies packages was positive, majority (78.1%) of the respondents agreed with the positive statements on adoption of post-harvest technologies, implying the possibility of high level of adoption of post-harvest technologies. The perception of the food crops farmers also had influence on adoption level of the selected post-harvest technologies packages with (P < 0.05). The study concluded that food crops farmers had positive perception of post-harvest technologies in the study area and the study therefore, recommends that Extension should make the technologies available along with training.Int. J. Agril. Res. Innov. & Tech. 7 (2): 22-26, December, 2017

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