Measurement of Model Parameters Versus Gas Pressure in High-Performance Plasma Focus NX1 and NX2 Operated in Neon

2017 ◽  
Vol 45 (8) ◽  
pp. 2292-2297 ◽  
Author(s):  
Prakash Gautam ◽  
Raju Khanal ◽  
Sor Heoh Saw ◽  
Sing Lee
Keyword(s):  
Plasma Focus ◽  
High Performance ◽  
Gas Pressure ◽  
Model Parameters

Model Parameters Versus Gas Pressure in Two Different Plasma Focus Devices Operated in Argon and Neon

2011 ◽  
Vol 31 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Sh. Al-Hawat ◽  
M. Akel ◽  
S. Lee ◽  
S. H. Saw
Keyword(s):  
Plasma Focus ◽  
Gas Pressure ◽  
Model Parameters

scholarly journals On the ship course-keeping control system design by using robust feedback linearization

2013 ◽  
Vol 20 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Zenon Zwierzewicz
Keyword(s):  
Feedback Linearization ◽  
High Performance ◽  
Linearization Method ◽  
Model Parameters ◽  
Control System Design ◽  
Control Approach ◽  
Ship Model ◽  
Control Techniques ◽  
System Nonlinearity ◽  
Ship Autopilot

Abstract In the paper the problem of ship autopilot design based on feedback linearization method combined with the robust control approach, is considered. At first the nonlinear ship model (of Norrbin type) is linearized with the use of the simple system nonlinearity cancellation. Next, bearing in mind that exact values of the model parameters are not known, the ensuing inaccuracies are taken as disturbances acting on the system. Thereby is obtained a linear system with an extra term representing the uncertainty which can be treated by using robust, H∞ optimal control techniques. The performed simulations of ship course-changing process confirmed a high performance of the proposed controller despite the assumed significant errors of its parameters.

scholarly journals Improving probabilistic flood forecasting through a data assimilation scheme based on genetic programming

2012 ◽  
Vol 12 (12) ◽  
pp. 3719-3732 ◽  
Author(s):  
L. Mediero ◽  
L. Garrote ◽  
A. Chavez-Jimenez
Keyword(s):  
Data Assimilation ◽  
Genetic Programming ◽  
Real Time ◽  
High Performance ◽  
Forecast Model ◽  
Flood Forecasting ◽  
Distribution Functions ◽  
Model Parameters ◽  
Hydrological Process ◽  
Model Based

Abstract. Opportunities offered by high performance computing provide a significant degree of promise in the enhancement of the performance of real-time flood forecasting systems. In this paper, a real-time framework for probabilistic flood forecasting through data assimilation is presented. The distributed rainfall-runoff real-time interactive basin simulator (RIBS) model is selected to simulate the hydrological process in the basin. Although the RIBS model is deterministic, it is run in a probabilistic way through the results of calibration developed in a previous work performed by the authors that identifies the probability distribution functions that best characterise the most relevant model parameters. Adaptive techniques improve the result of flood forecasts because the model can be adapted to observations in real time as new information is available. The new adaptive forecast model based on genetic programming as a data assimilation technique is compared with the previously developed flood forecast model based on the calibration results. Both models are probabilistic as they generate an ensemble of hydrographs, taking the different uncertainties inherent in any forecast process into account. The Manzanares River basin was selected as a case study, with the process being computationally intensive as it requires simulation of many replicas of the ensemble in real time.

scholarly journals Efficient Low-Complexity Digital Predistortion for Power Amplifier Linearization

2016 ◽  
Vol 6 (3) ◽  
pp. 1096
Author(s):  
Siba Monther Yousif ◽  
Roslina M. Sidek ◽  
Anwer Sabah Mekki ◽  
Nasri Sulaiman ◽  
Pooria Varahram
Keyword(s):  
Power Amplifier ◽  
High Performance ◽  
Low Complexity ◽  
Memory Effects ◽  
Model Complexity ◽  
Model Parameters ◽  
Digital Predistortion ◽  
Nonlinear Memory ◽  
Proposed Model ◽  
Code Division Multiple

<span lang="EN-US">In this paper, a low-complexity model is proposed for linearizing power amplifiers with memory effects using the digital predistortion (DPD) technique. In the proposed model, the linear, low-order nonlinear and high-order nonlinear memory effects are computed separately to provide flexibility in controlling the model parameters so that both high performance and low model complexity can be achieved. The performance of the proposed model is assessed based on experimental measurements of a commercial class AB power amplifier by applying a single-carrier wideband code division multiple access (WCDMA) signal. The linearity performance and the model complexity of the proposed model are compared with the memory polynomial (MP) model and the DPD with single-feedback model. The experimental results show that the proposed model outperforms the latter model by 5 dB in terms of adjacent channel leakage power ratio (ACLR) with comparable complexity. Compared to MP model, the proposed model shows improved ACLR performance by 10.8 dB with a reduction in the complexity by 17% in terms of number of floating-point operations (FLOPs) and 18% in terms of number of model coefficients.</span>

scholarly journals Local Virtual Times Analysis in PCS Model

2021 ◽  
Author(s):  
Liliia Ziganurova ◽  
Lev Shchur
Keyword(s):  
High Performance ◽  
Essential Feature ◽  
Discrete Event ◽  
Universality Class ◽  
Personal Communication ◽  
Surface Growth ◽  
Model Parameters ◽  
Discrete Event Simulations ◽  
Zone Cell ◽  
Parallel Discrete Event

Efficient scalability and process synchronization are critical for achieving high performance in distributed computing environments. Analysis of the scalability is usually done using intensive case studies, which give an answer only for the particular set of model parameters. We found an efficient way to analyze the time evolution in models simulated with the Parallel Discrete Event Simulations (PDES) approach. The essential feature of PDES is the concept of local virtual time (LVT) associated with the evolution of each process of the model. The LVT of processes evaluates in simulations and forms a complicated profile.These profiles remind the profiles of the surface growth in the physical devices. In physics, researchers use the concept of universality, which helps to divide the different regimes of the class's surface growth—each class is described by some universal laws and does not depend on the details of the model. We demonstrate the applicability of this concept and present a model of LVT profile evolution in Personal Communication Service (PCS) model. The PCS network consists of a square grid of radio ports that serve users in their zone (cell). We build the LVT-PCS model, which describes the evolution of the LVT profile associated with the PCS model. We simulate the PCS model using the ROSS simulator (optimistic PDES) and compare results with those simulated by our LVT-PCS model. We found the profile demonstrates property, which is known in physics as roughening transition. We estimate the values of ``critical’’ exponents for two models, which seem to belong to the same universality class. We believe that the similarity we found can be helpful for the preliminary analysis of the model scalability, process desynchronization, and possible deadlocks.

Chaos Control in Single Mode Approximation of T-AFM Systems Using Nonlinear Delayed Feedback Based on Sliding Mode Control

2007 ◽  
Author(s):  
Hoda Sadeghian ◽  
Mehdi Tabe Arjmand ◽  
Hassan Salarieh ◽  
Aria Alasty
Keyword(s):  
Feedback Control ◽  
High Performance ◽  
Sliding Mode ◽  
Chaotic Behavior ◽  
Single Mode ◽  
Delayed Feedback ◽  
Delayed Feedback Control ◽  
Model Parameters ◽  
Unstable Periodic Orbits ◽  
Single Mode Approximation

The taping mode Atomic Force Microscopic (T-AFM) can be properly described by a sinusoidal excitation of its base and nonlinear potential interaction with sample. Thus the cantilever may cause chaotic behavior which decreases the performance of the sample topography. In this paper a nonlinear delayed feedback control is proposed to control chaos in a single mode approximation of a T-AFM system. Assuming model parameters uncertainties, the first order Unstable Periodic Orbits (UPOs) of the system is stabilized using the sliding nonlinear delayed feedback control. The effectiveness of the presented methods is numerically verified and the results show the high performance of the controller.

Application of Mathematical Methods to Determine the Field Parameters Related to Diffusion of Methane Gas in a Bulli Seam

1986 ◽  
Vol 10 (4) ◽  
pp. 185-190 ◽  
Author(s):  
A. Basu ◽  
R. D. Lama
Keyword(s):  
Gas Flow ◽  
Darcy’S Law ◽  
Darcy's Law ◽  
Gas Pressure ◽  
Model Parameters ◽  
Fick’S Law ◽  
Mathematical Methods ◽  
Fick's Law ◽  
Diffusion Parameters ◽  
Field Diffusion

The paper describes the application of a mathematical model to describe gas drainage in coal seams. The mechanism of gas flow from coal is not very clear at present. It can either follow Darcy’s law or Fick’s law of diffusion. In the opinion of the authors, a the earlier stages where the gas pressure is high, Darcy’s law applies [8]. At later stages when gas pressure is stabilised, Fick’s law of diffusion is applicable. In this study, therefore, Fick’s law has been applied. Experimental techniques for measuring the system model parameters such as in situ gas pressure and Langmuir’s constants are described. The solutions have been applied in a field experiment to determine field diffusion parameters.

scholarly journals Improvements to the hydrological processes of the Town Energy Balance model (TEB-Veg, SURFEX v7.3) for urban modelling and impact assessment

2018 ◽  
Vol 11 (10) ◽  
pp. 4175-4194 ◽  
Author(s):  
Xenia Stavropulos-Laffaille ◽  
Katia Chancibault ◽  
Jean-Marc Brun ◽  
Aude Lemonsu ◽  
Valéry Masson ◽  
...  
Keyword(s):  
Energy Balance ◽  
High Performance ◽  
Hydrological Processes ◽  
Balance Model ◽  
Statistical Criterion ◽  
Model Parameters ◽  
Water Drainage ◽  
Deep Drainage ◽  
Complete Representation ◽  
The Town

Abstract. Climate change and demographic pressures are affecting both the urban water balance and microclimate, thus amplifying urban flooding and the urban heat island phenomena. These issues need to be addressed when engaging in urban planning activities. Local authorities and stakeholders have therefore opted for more nature-based adaptation strategies, which are especially suitable in influencing hydrological and energy processes. Assessing the multiple benefits of such strategies on the urban microclimate requires high-performance numerical tools. This paper presents recent developments dedicated to the water budget in the Town Energy Balance for vegetated surfaces (TEB-Veg) model (surface externalisée; SURFEX v7.3), thus providing a more complete representation of the hydrological processes taking place in the urban subsoil. This new hydrological module is called TEB-Hydro. Its inherent features include the introduction of subsoil beneath built surfaces, the horizontal rebalancing of intra-mesh soil moisture, soil water drainage via the sewer network and the limitation of deep drainage. A sensitivity analysis is then performed in order to identify the hydrological parameters required for model calibration. This new TEB-Hydro model is evaluated on two small residential catchments in Nantes (France), over two distinct periods, by comparing simulated sewer discharge with observed findings. In both cases, the model tends to overestimate total sewer discharge and performs better under wet weather conditions, with a Kling–Gupta efficiency (KGE) statistical criterion greater than 0.80 vs. approximately 0.60 under drier conditions. These results are encouraging since the same set of model parameters is identified for both catchments, irrespective of meteorological and local physical conditions. This approach offers opportunities to apply the TEB-Hydro model at the city scale alongside projections of climate and demographic changes.

A neutron source with 1014 DT neutron yield

2019 ◽  
Vol 28 (11) ◽  
pp. 1950097 ◽  
Author(s):  
Yasar Ay
Keyword(s):  
Neutron Source ◽  
Plasma Focus ◽  
Neutron Yield ◽  
Pressure Range ◽  
Gas Pressure ◽  
Plasma Focus Device ◽  
Operational Conditions ◽  
Rate Of Increase ◽  
Spherical Plasma ◽  
High Neutron

The developed spherical plasma focus model is used in this study to investigate the optimum neutron yield in terms of the gas pressure, cathode radius and external inductance. The optimum values for these parameters are found separately. Then, the charging voltage is varied from 25[Formula: see text]kV to 35[Formula: see text]kV with 1[Formula: see text]kV increment by using these separately found optimum values to see the rate of increase in neutron yield. While the used gas pressure range is 1–40[Formula: see text]Torr with 1[Formula: see text]Torr increment, cathode radius range is 11.5–17[Formula: see text]cm with 0.5[Formula: see text]cm increment. External inductance is varied from 10[Formula: see text]nH to 150[Formula: see text]nH with 5[Formula: see text]nH increment. The optimum values for gas pressure, cathode radius and external inductance are found to be 26[Formula: see text]Torr, 15[Formula: see text]cm and 75[Formula: see text]nH, respectively. Even though combining these separately found optimum values of pressure, cathode radius and external inductance does not necessarily form an optimized set of operational conditions for the SPF, they lead to a higher neutron yield in that while neutron yield with these separately found optimum values at 25[Formula: see text]kV charging voltage is [Formula: see text] (higher than the measured neutron yield of [Formula: see text] at 25[Formula: see text]kV), it increases to [Formula: see text], when charging voltage is increased to 35[Formula: see text]kV. Using these values shows that spherical plasma focus device can be used as a neutron source with high neutron yield (on the order of [Formula: see text]).

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