Three Pressure Peaks Analysis for the TEPCO Fukushima Daiichi Unit 2 by the SAMPSON Code

2017 ◽  
Author(s):  
Chiaki Kino ◽  
Hiroaki Suzuki ◽  
Itsuo Yoshioka ◽  
Hidetoshi Okada ◽  
Masanori Naitoh
Keyword(s):  
Hydraulic Model ◽  
Relief Valve ◽  
Basic Tendency ◽  
The Core ◽  
Fukushima Daiichi ◽  
Simulation Results

In view of the 1F decommissioning project, the Institute of Applied Energy (IAE) has been analyzing the course of the accident using the SAMPSON code with an aim to investigate its progression in detail. For 1F Unit-2, certain discrepancies between measurement values and analysis results still exist. For example, although three pressure peaks occur after a manual activation of a safety relief valve (SRV), its mechanism is yet unclear. This study seeks to elucidate the mechanism for the three pressure peaks using a new presumption for the relocation of the debris through the lower part of the core. The current results could reproduce the basic tendency for each peak. However, some deviations between simulation results and measured values indicate the necessity for further improvement of the thermal-hydraulic model used in SAMPSON.

scholarly journals A modular framework to generate robust biped locomotion: from planning to control

2021 ◽  
Vol 3 (9) ◽  
Author(s):  
Mohammadreza Kasaei ◽  
Ali Ahmadi ◽  
Nuno Lau ◽  
Artur Pereira
Keyword(s):  
Numerical Simulations ◽  
Predictive Control ◽  
Biped Locomotion ◽  
Input Output ◽  
Dynamics Model ◽  
Biped Robots ◽  
The Core ◽  
Simulation Results ◽  
Reference Trajectories ◽  
Modular Framework

AbstractBiped robots are inherently unstable because of their complex kinematics as well as dynamics. Despite many research efforts in developing biped locomotion, the performance of biped locomotion is still far from the expectations. This paper proposes a model-based framework to generate stable biped locomotion. The core of this framework is an abstract dynamics model which is composed of three masses to consider the dynamics of stance leg, torso, and swing leg for minimizing the tracking problems. According to this dynamics model, we propose a modular walking reference trajectories planner which takes into account obstacles to plan all the references. Moreover, this dynamics model is used to formulate the controller as a Model Predictive Control (MPC) scheme which can consider some constraints in the states of the system, inputs, outputs, and also mixed input-output. The performance and the robustness of the proposed framework are validated by performing several numerical simulations using MATLAB. Moreover, the framework is deployed on a simulated torque-controlled humanoid to verify its performance and robustness. The simulation results show that the proposed framework is capable of generating biped locomotion robustly.

Simulation Analysis and Optimization of Lubricating Oil System

2021 ◽  
Author(s):  
Qiongxiao Wu ◽  
Jianjun Wang ◽  
Jingming Chen ◽  
Pengzheng Li
Keyword(s):  
Simulation Model ◽  
Simulation Analysis ◽  
Sudden Change ◽  
Pressure Change ◽  
Lubricating Oil ◽  
Maximum Pressure ◽  
Closing Time ◽  
Original Design ◽  
Relief Valve ◽  
Simulation Results

Abstract Based on the one-dimensional simulation model of lubricating oil system is established and analyzed by using FLOWMASTER software, this paper proposes a new method of optimizing lubricating oil system by PID technology. Ensure that the configuration requirements and control strategies of the relevant accessories of the simulation model are satisfied with the design requirements. Firstly, by simulating lubricating oil pressure fluctuation and lubricating oil flow distribution under Open/Close Valve in different opening and closing time, the optimal opening/closing time of Open/Close Valve is determined to be 0.2 s and 0.5 s respectively. Secondly, by writing the controller script file combined with a controller to realize automatic unloading relief valve simulation, determine the relief valve pressure regulating range of 0∼0.38 MPa, For precision of constant pressure valve of oil spill, the simulation results show that the average 10 m3/h flow caused by pressure changes of about 0.06 MPa. Under the flow sudden change signal of about 40 m3/h, the maximum pressure change is less than 0.1 MPa. Through the simulation results, it is found that most of the lubrication parts in the original design have the phenomenon of flow redundancy, which causes unnecessary pump power loss. The system is optimized by PID technology. By comparing the simulation results before and after optimization, it is found that the speed of constant displacement pump could be changed in time by PID controller, and the flow redundancy could be improved significantly, so the lubricating oil system could be lower consumption and achieve the purpose of optimization.

Numerical Simulation of the Stress Field of Thick 7B04 Aluminum Alloy Board during Continuous Manufacture Procedure

2007 ◽  
Vol 127 ◽  
pp. 259-264
Author(s):  
Hong Yuan Fang ◽  
Cheng Iei Fan
Keyword(s):  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Stress Concentration ◽  
Stress Field ◽  
Solution Treatment ◽  
Simulation Method ◽  
The Core ◽  
Manufacturing Procedure ◽  
Continuous Manufacture ◽  
Simulation Results

Numerical simulation method is employed in the article to analyze the stress field of thick 7B04 aluminum alloy board during manufacturing procedure of solution treatment, calendaring and stretching. The simulation results show that the surface of the board endures compressive stress while the core segment endures tensile stress, and the distribution of the stress is very inhomogeneous. The calendaring procedure helps to decrease the stress and redistribute the stress uniformly, but it also leads to stress concentration at the two ends of the board, which engenders bad influence on the subsequent processing. The board deforms plastically when being stretched, thus the stress decreases greatly and is redistributed uniformly.

scholarly journals A Combined Method for Predicting the Boron Deposited Mass and the CIPS Risk

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Shengzhe Li ◽  
Dongmei Yang ◽  
Tengfei Zhang ◽  
Xiaojing Liu
Keyword(s):  
Power Distribution ◽  
Neutron Cross Section ◽  
Local Power ◽  
Combined Method ◽  
Boron Compounds ◽  
The Core ◽  
Simulation Results ◽  
Deposit Model ◽  
Power Distribution Control ◽  
The Impact

CIPS is a shift in the axial power towards the bottom half of the core, also known as axial offset anomaly (AOA), which results from the deposited of corrosion products during an operation. The main reason of CIPS is the solute particles especially boron compounds concentrated inside the porous deposit. The impact of CIPS is that the axial power distribution control may be more difficult and the shutdown margin can be decreased simultaneously. Besides, it also requires estimated critical condition (ECC) calculations to account for the effects of AOA. In this article, thermal-hydraulic subchannel code and boron deposit model have been combined to analyze the CIPS risk. The neutronics codes deal with the generation of homogenized neutron cross section as well as the calculation of local power factor. A simple rod assembly is analyzed with this combined method and simulation results are presented. Simulation results provide the boron hideout amount inside crud deposits and power shapes. The obtained results clearly show the power shape suppression in regions where crud deposits exist, which is a clear indication of CIPS phenomenon. And the CIPS effects on CHF have also been investigated. Result shows a margin of DNBR decrease in the crud case.

scholarly journals Novel Remanence Determination for Power Transformers Based on Magnetizing Inductance Measurements

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4616
Author(s):  
Chen Wei ◽  
Xianqiang Li ◽  
Ming Yang ◽  
Zhiyuan Ma ◽  
Hui Hou
Keyword(s):  
Numerical Simulations ◽  
Laboratory Experiments ◽  
Power Transformer ◽  
Power Transformers ◽  
Inrush Current ◽  
The Core ◽  
Novel Method ◽  
Simulation Results ◽  
Electro Magnetic ◽  
The Relationship

The remanence (residual flux) in the core of power transformers needs to be determined in advance to eliminate the inrush current during the process of re-energization. In this paper, a novel method is proposed to determine the residual flux based on the relationship between residual flux and the measured magnetizing inductance. The paper shows physical, numerical, and analytical explanations on the phenomenon that the magnetizing inductance decreases with the increase of residual flux under low excitation. Numerical simulations are performed by EMTP (Electro-Magnetic Transient Program) on a 1 kVA power transformer under different amounts of residual flux. The inductance–remanence curves are nearly the same when testing current changes. Laboratory experiments conducted on the same transformer are in line with the numerical simulations. Furthermore, numerical simulation results on a 240 MVA are reported to demonstrate the effectiveness of the proposed method.

Investigation of Discrepancies in Waterhammer Structural Integrity Analysis Simulation and Actual Vibration Testing

2009 ◽  
Author(s):  
Khalid Chaudhry ◽  
Andrei Blahoianu
Keyword(s):  
Structural Integrity ◽  
Linear Analysis ◽  
Relief Valve ◽  
Pressure Time ◽  
Asme Code ◽  
Time Histories ◽  
Valve Opening ◽  
Simulation Results ◽  
Measured Displacement ◽  
Integrity Analysis

While verifying the Primary Heat Transport (PHT) piping design for increased waterhammer loads due to sudden relief valve opening, it was discovered that linear piping analysis FEA program, which was relied upon extensively in the past, predicted overly conservative results. By overestimating the piping stresses, the stress results did not satisfy the ASME code, Section III, subsection NB-3652 Equation 9 limits for Level B service loading. During the course of investigation to meet ASME code limits, the licensee carried out a series of controlled actual waterhammer tests on thoroughly instrumented PHT piping and recorded the measured piping displacements. Waterhammer pressure-time histories created from these actual tests were then used as input into the standard linear piping analyses to compare analysis simulation results with the actual measured displacement data. It was observed that the analysis simulation results overestimated the piping displacement results by a large margin, i.e., by a factor of 5. A further insight into the analysis results indicated the presence of a single, the so called “killer” mode of vibration which accounted for nearly all of the PHT piping displacement response to test waterhammer loading. On a hypothetical basis, a restraint was applied in the direction of vibration of the pipe and the linear analysis was repeated. It was discovered that the simulated analytical piping response using a modified restraint had a much better match with the displacement results obtained during the actual test. From this hypothetical restraint application, it was inferred that friction between the supports and the pipe is the key ingredient which dampens the pipe oscillations and hence a lower response during the test than the linear analysis which does not consider the friction between the pipe and its guide support. This paper further investigates the contribution of structural damping, friction effects between the pipe and its supports (use of contact elements), fluid structure interactions and issues related to application of friction to carry out ‘modified’ nonstandard analyses to better predict the piping response to waterhammer transient loading.

Molecular Dynamics Simulations of Nanocomposite Diamond-Like Carbon

2005 ◽  
Author(s):  
G. T. Gao ◽  
J. D. Schall ◽  
K. Van Workum ◽  
P. T. Mikulski ◽  
J. A. Harrison
Keyword(s):  
Molecular Dynamics ◽  
Elastic Constants ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Diamond Structure ◽  
The Core ◽  
Constant Tension ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Carbon Network

A constant tension and constant temperature molecular dynamics simulation method was used in the calculations of the elastic constants of the nanocomposite systems. The nanocomposite systems contain a core of sp3 diamond structure surrounded by an amorphous carbon network. The simulation results show that the elastic properties of nanocomposites of diamond-like carbons are closely related to the size of the sp3 diamond core; the bigger the core, the larger the elastic constants, and the system becomes more anisotropic.

An efficient improved routing strategy for multilayer networks

2020 ◽  
pp. 2150078
Author(s):  
Jinlong Ma ◽  
Min Li ◽  
Yaming Li ◽  
Xiangyang Xu ◽  
Weizhan Han ◽  
...  
Keyword(s):  
Multilayer Structure ◽  
High Speed ◽  
Multilayer Networks ◽  
Traffic Dynamics ◽  
The Core ◽  
Transmission Process ◽  
Routing Strategy ◽  
Traffic Capacity ◽  
Average Transmission ◽  
Simulation Results

Traffic dynamics of multilayer networks draws continuous attention from different communities since many systems are actually proved to have a multilayer structure. Since the core nodes of network are prone to congested, an effective routing strategy is of great significance to alleviate the congestion of the multilayer networks. In this paper, we propose an efficient improved routing strategy, with which the core nodes that can reasonably avoid congestion at the high-speed layer in the transmission process of packets, and can also make the most of the traffic resources of the low-speed layer nodes to optimize the traffic capacity of multilayer networks. The simulation results show that the proposed routing strategy can not only improve the network traffic capacity, but also shorten the average path length and average transmission time.

Research and Design for Relief Valve with Level 2 Pressure Regulating Based on AMEsim

2012 ◽  
Vol 246-247 ◽  
pp. 754-758
Author(s):  
Ren Yu Feng ◽  
Hai Lan Wang ◽  
Zhen Jie Hao
Keyword(s):  
Dynamic Performance ◽  
Valve Design ◽  
Relief Valve ◽  
Theoretical Support ◽  
Product Test ◽  
Simulation Results ◽  
Test Verification ◽  
The Impact ◽  
Research And Design ◽  
Level 2

By the relief valve with level 2 pressure regulating structures AMEsim model to analyze the impact of various factors on the valve dynamic performance reasons; optimize the parameters of these factors in the theoretical support and click here to design methods of productionthe product test verification. The results prove the effectiveness of the proceeds of the correctness of the simulation results and the valve design and production process.

EFFECT OF ELECTRIC FIELD, TEMPERATURE AND CORE DIMENSIONS IN III–V COMPOUND CORE–SHELL NANOWIRES

NANO ◽  
2014 ◽  
Vol 09 (04) ◽  
pp. 1450051
Author(s):  
ASHWANI VERMA ◽  
BAHNIMAN GHOSH ◽  
AKSHAY KUMAR SALIMATH
Keyword(s):  
Monte Carlo ◽  
Electric Field ◽  
Spin Relaxation ◽  
Compound Semiconductor ◽  
Core Shell ◽  
Relaxation Length ◽  
The Core ◽  
Field Temperature ◽  
Simulation Results ◽  
Shell Nanowires

In this paper, we have used semiclassical Monte Carlo method to show the dependence of spin relaxation length in III–V compound semiconductor core–shell nanowires on different parameters such as lateral electric field, temperature and core dimensions. We have reported the simulation results for electric field in the range of 0.5–10 kV/cm, temperature in the range of 77–300 K and core length ranging from 2 nm to 8 nm. The spin relaxation mechanisms used in III–V compound semiconductor core–shell nanowire are D'yakonov–Perel (DP) relaxation and Elliott–Yafet (EY) relaxation. Depending upon the choice of materials for core and shell, nanowire forms two types of band structures. We have used InSb – GaSb core–shell nanowire and InSb – GaAs core–shell nanowire and nanowire formed by swapping the core and shell materials to show all the results.

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