scholarly journals High-Speed Monitoring of Dust Particles in ITER ELMs Simulation Experiments with QSPA Kh-50

10.14311/1759 ◽  
2013 ◽  
Vol 53 (2) ◽  
Author(s):  
Vadym A. Makhlaj ◽  
Igor E. Garkusha ◽  
Nikolay N. Aksenov ◽  
Alexander A. Chuvilo ◽  
Igor S. Landman
Keyword(s):  
Heat Load ◽  
High Speed ◽  
Plasma Accelerator ◽  
Dust Particles ◽  
Plasma Stream ◽  
Maximal Velocity ◽  
Start Time ◽  
Simulation Experiments ◽  
Dust Generation ◽  
Load Average

Dust generation under powerful plasma stream impacts has been studied in ITER ELM simulation experiments with QSPA Kh-50 plasma accelerator. Repetitive plasma exposures of tungsten have been performed by 0.25 ms plasma pulses and the heat load varied in the range (0.1÷1.1) MJm-2. Main characteristics of dust particles such as a number of ejected particles, their velocity, angular distribution and start time from the surface are investigated. Dust particles have not been observed under heat load below the cracking threshold. Quantity of dust particles rises with increasing heat load. Average velocities of dust particles are found to be strongly dependent on their start time from the surface after beginning of plasma-surface interaction. Maximal velocity achieved a few tens of meters per second.

scholarly journals Modelling of dust generation, transport and remobilization in full-metal fusion reactors

2022 ◽  
Author(s):  
Svetlana Ratynskaia ◽  
Ladislas Vignitchouk ◽  
Panagiotis Tolias
Keyword(s):  
Initial Conditions ◽  
External Input ◽  
Dust Particles ◽  
Fusion Reactors ◽  
Dust Production ◽  
Dust Transport ◽  
Dust Generation ◽  
Wall Interaction ◽  
And Migration ◽  
Generation Mechanisms

Abstract The design, licensing and operation of magnetic confinement fusion reactors impose various limitations on the amount of metallic dust particles residing inside the plasma chamber. In this context, predictive studies of dust production and migration constitute one of the main sources of relevant data. These are mainly conducted using dust transport codes, which rely on coupled dust-plasma and dust-wall interaction models, and require external input on the dust and droplet initial conditions. Some particularities of dust modelling in reactor-relevant conditions are analyzed with an emphasis on dust generation mechanisms relevant for disruption scenarios and on dust remobilization mechanisms relevant for ramp-up scenarios. Emerging topics such as dust production by runaway electron impact and pre-plasma remobilization of magnetic dust are also discussed.

scholarly journals Numerical Study of Longitudinal Inter-Distance and Operational Characteristics for High-Speed Capsular Train Systems

Vehicles ◽  
2022 ◽  
Vol 4 (1) ◽  
pp. 30-41
Author(s):  
Bruce W. Jo
Keyword(s):  
Error Rate ◽  
High Speed ◽  
Position Control ◽  
Numerical Study ◽  
Design Parameters ◽  
Maximum Speed ◽  
Integer Number ◽  
Vehicle Speed ◽  
Start Time ◽  
Distance Control

High-speed capsular vehicles are firstly suggested as an idea by Elon Musk of Tesla Company. Unlike conventional high-speed trains, capsular vehicles are individual vessels carrying passengers and freight with the expected maximum speed of near 1200 [km/h] in a near-vacuum tunnel. More individual vehicle speed, dispatch, and position control in the operational aspect are expected over connected trains. This numerical study and investigation evaluate and analyze inter-distance control and their characteristics for high-speed capsular vehicles and their operational aspects. Among many aspects of operation, the inter-distance of multiple vehicles is critical toward passenger/freight flow rate and infrastructural investment. In this paper, the system’s equation, equation of the motion, and various characteristics of the system are introduced, and in particular control design parameters for inter-distance control and actuation are numerically shown. As a conclusion, (1) Inter-distance between vehicles is a function of error rate and second car start time, the magnitude range is determined by second car start time, (2) Inter-distance fluctuation rate is a function of error rate and second car start time, however; it can be minimized by choosing the correct second car start time, and (3) If the second car start time is chosen an integer number of push-down cycle time at specific velocity error rate, the inter-distance fluctuation can be zero.

scholarly journals Investigation of optical glass characteristics under the influence of space factors

2019 ◽  
Vol 43 (5) ◽  
pp. 803-809
Author(s):  
М.P. Kalaev ◽  
А.М. Telegin ◽  
K.E. Voronov ◽  
Jiang Lixiang ◽  
Jiao Jilong
Keyword(s):  
Experimental Study ◽  
Optical Properties ◽  
High Speed ◽  
Optical Glass ◽  
Outer Space ◽  
Characteristic Size ◽  
Dust Particles ◽  
Spectral Transmittance ◽  
Ability To Work ◽  
High Speed Flows

The paper describes a DF-OPTICS device that the present authors designed for the experimental study of changes in the optical properties of a glass whose surface is exposed to high-speed flows of micron-sized dust particles. The device allows the scattering indicatrix and the spectral transmittance to be automatically measured at each point of the sample with a 0.5-mm increment. Advantages of the developed device include small dimensions and the ability to work in vacuum, allowing it to be used in an accelerator chamber to simulate outer space factors. Experimental results for the K-8 glass put in a microparticle accelerator and bombarded by an aluminum powder PAP-1 with a characteristic size of 1-3 µm and speeds of 2-8 km / s are presented. The device makes it possible to measure the change of the spectral transmittance of transparent materials in the UV and RGB regions with an accuracy of 0.005%, which exceeds the sensitivity of some known spectrophotometers.

scholarly journals Ice Particle Emission from Cometary Analogues

1991 ◽  
Vol 126 ◽  
pp. 257-260
Author(s):  
H. Kohl ◽  
E. Grün
Keyword(s):  
Cometary Nucleus ◽  
Interplanetary Dust ◽  
Particle Emission ◽  
Dust Particles ◽  
Vacuum System ◽  
Simulation Experiments ◽  
Water Ice ◽  
Mineral Particles ◽  
Nucleus Surface ◽  
Particle Ejection

AbstractDust particles originating from comets are an important constituent of the interplanetary dust regime. In order to study the ejection mechanisms from the cometary nucleus surface simulation experiments in the laboratory have been performed. Samples consisting of water ice, carbon dioxide ice and dust grains have been studied when they are irradiated by artificial sunlight within a cooled vacuum system. It has been shown that particle emission is extremely dependent on the initial composition of the samples. For samples with a distinct amount of non-volatile, mineral particles the formation of a dust mantle and, as a consequence, rapid decrease of particle ejection has been observed.

scholarly journals Research on Safety Technology for High-Speed Interruption for Mining Flameproof Movable Substation

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 934
Author(s):  
Yanwen Wang ◽  
Le Wang ◽  
Sven G. Bilén ◽  
Yan Gao
Keyword(s):  
Solid State ◽  
High Speed ◽  
Single Phase ◽  
Low Voltage ◽  
Short Circuit ◽  
Rate Of Change ◽  
Simulation Experiments ◽  
Gas Detonation ◽  
Ultra High Speed ◽  
Short Circuit Fault

Due to the working condition of low-voltage cabling from the mining flameproof movable substation to the loads of the mining face being poor, it is easy to cause various external mechanical damages to the cable sheaths. Furthermore, a single-phase earth leakage fault or short-circuit fault can occur when the low-voltage cable sheaths are damaged, and electric sparks caused by these faults can lead to a gas explosion. As the gas detonation time caused by the above faults is usually more than 5 ms, the high-speed interruption solid-state switch which controls the cables must cut off the current within 3 ms. This requires the action time of the solid-state switch to be less than 1 ms, and at the same time, the sampling and calculation time of the relay protection must be less than 2 ms. Based on these problems, this paper proposes the use of a high-speed solid-state circuit breaker (SSCB) topology at the neutral point of transformer, and analyzes the conduction mechanism and shut-off mechanism of the current of the SSCB. It presents an ultra-high-speed algorithm based on pattern recognition of single-phase earth leakage fault protection, and an ultra-high-speed algorithm of short-circuit fault which is based on the rate-of-change of the current. Finally, through computer simulation experiments and semi-physical simulation experiments, the feasibility of the above three technologies is verified to ensure that when a single-phase earth leakage fault or short-circuit fault occurs in the low-voltage cable, the solid-state switch which is installed in the mining flameproof movable substation will cut off the current within 3 ms.

Research on a New Flexible Acceleration and Deceleration Algorithm with Continuous Jerk

2011 ◽  
Vol 291-294 ◽  
pp. 286-289
Author(s):  
Jian Ren Sun ◽  
Chi Bing Hu
Keyword(s):  
High Speed ◽  
System Development ◽  
Trigonometric Function ◽  
Sine Function ◽  
Simulation Experiments ◽  
Sine Curve ◽  
Motion System ◽  
Motion Process ◽  
Acceleration And Deceleration ◽  
Shape Curve

Control of the motion process of acceleration/deceleration (Acc/Dec) is one of key complicated problems in CNC system development. The excellent Acc/Dec control can improve the processing precision. The traditional Acc/Dec algorithms such as the linear and the exponential are not suitable for high speed motion because there would be flexible impacts existing in feed motion, especially that the jerk of the S-shape curve Acc/Dec is discontinuous. A new flexible Acc/Dec algorithm for high speed motion system based on the squared sine function is introduced. The modeling of the Acc/Dec algorithm with Trigonometric Function Squared Sine(TFSS) shape curve is constructed.In this algorithm, the sine curve in jerk, acceleration, velocity and displacement are all continuous. The simulation experiments result demonstrate that the Acc/Dec algorithm with TFSS shape curve is a new method of continuous Jerk for the design flexible Acc/Dec.

scholarly journals Kinematics of Usain Bolt’s maximal sprint velocity

Kinesiology ◽  
2018 ◽  
Vol 50 (2) ◽  
pp. 172-180 ◽  
Author(s):  
Milan Čoh ◽  
Kim Hébert-Losier ◽  
Stanko Štuhec ◽  
Vesna Babić ◽  
Matej Supej
Keyword(s):  
Ground Reaction Force ◽  
High Speed ◽  
Reaction Force ◽  
Vertical Displacement ◽  
Biomechanical Analysis ◽  
Maximal Velocity ◽  
Vertical Ground Reaction Force ◽  
Mean Velocity ◽  
Vertical Ground ◽  
Sprint Velocity

This study investigated the maximal sprint velocity kinematics of the fastest 100 m sprinter, Usain Bolt. Two high-speed video cameras recorded kinematics from 60 to 90 m during the men 100 m final at the IAAF World Challenge Zagreb 2011, Croatia. Despite a relatively slow reaction time (194 ms), Bolt won in 9.85 s (mean velocity: 10.15 m/s). His fastest 20-m section velocity was 12.14 m/s, reached between 70 and 90 m, by 2.70-m long strides and 4.36 strides/s frequency. At the maximal velocity, his contact and flight times were 86 and 145 ms, respectively, and vertical ground reaction force generated equalled 4.2 times his body weight (3932 N). The braking and propulsion phase represented 37% and 63% of ground contact, respectively, with his centre of mass (CoM) exhibiting minor reductions in horizontal velocity (2.7%) and minimal vertical displacement (4.9 cm). Emerged Bolt’s maximal sprint velocity and international predominance from coordinated motor abilities, power generation capacities, and effective technique. This study confirms that his maximal velocity was achieved by means of relatively long strides, minimal braking phase, high vertical ground reaction force, and minimal vertical displacement of CoM. This study is the first in-depth biomechanical analysis of Bolt’s maximal sprinting velocity with the segmental reconstruction.

scholarly journals A Path-Planning Strategy for Unmanned Surface Vehicles Based on an Adaptive Hybrid Dynamic Stepsize and Target Attractive Force-RRT Algorithm

2019 ◽  
Vol 7 (5) ◽  
pp. 132 ◽  
Author(s):  
Zhen Zhang ◽  
Defeng Wu ◽  
Jiadong Gu ◽  
Fusheng Li
Keyword(s):  
Path Planning ◽  
High Speed ◽  
Attractive Force ◽  
Simulation Experiments ◽  
Planning Strategy ◽  
Unmanned Surface Vehicles ◽  
Planning Algorithm ◽  
Pass Through ◽  
Path Planning Algorithm ◽  
Narrow Area

It is well known that path planning has always been an important study area for intelligent ships, especially for unmanned surface vehicles (USVs). Therefore, it is necessary to study the path-planning algorithm for USVs. As one of the basic algorithms for USV path planning, the rapidly-exploring random tree (RRT) is popular due to its simple structure, high speed and ease of modification. However, it also has some obvious drawbacks and problems. Designed to perfect defects of the basic RRT and improve the performance of USVs, an enhanced algorithm of path planning is proposed in this study, called the adaptive hybrid dynamic stepsize and target attractive force-RRT(AHDSTAF-RRT). The ability to pass through a narrow area and the forward speed in open areas of USVs are improved by adopting the AHDSTAF-RRT in comparison to the basic RRT algorithm. The improved algorithm is also applied to an actual gulf map for simulation experiments, and the experimental data is collected and organized. Simulation experiments show that the proposed AHDSTAF-RRT in this paper outperforms several existing RRT algorithms, both in terms of path length and calculating speed.

Effect of Lance Nozzle Angle and Mixing Gas Blowing on BOF Process

2011 ◽  
Vol 402 ◽  
pp. 446-451
Author(s):  
Dong Xu ◽  
Da Qiang Cang ◽  
Ling Ling Zhang ◽  
Li Xue Qin ◽  
Jian Feng Duan
Keyword(s):  
Carbon Dioxide ◽  
Heat Load ◽  
Oxygen Lance ◽  
Rate Decrease ◽  
Dust Generation ◽  
Impact Area ◽  
Gas Blowing ◽  
The Impact

The hot experiment was carried out to study the effect of lance nozzle and mixing gas blowing on steelmaking. The heat load of oxygen lance, component in the bath and dust generation were studied in the hot experiment under different lances and mixing blowing process. The absorbed heat is lower and the slag adhesion on the oxygen lance is reduced with the lance nozzle angle increasing. By using small portion of carbon dioxide as top gas is help to reduce the temperature in the impact area and decrease the dust generation, but the decarbonization rate decrease with the proportion of carbon dioxide increasing.

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