Strike Position Research Articles

Validation of the strike point position estimation with the local expansion method for MAST upgrade on the DIII-D tokamak

A local expansion method has been proposed for estimating the strike point position for the advanced divertor configuration on the MAST Upgrade tokamak. The paper discusses the application and assesses the performance of the technique on a long-legged divertor plasma configuration on an operating device - the DIII-D tokamak. A comparison of the spatial location of the outer strike point estimated with the local expansion method against the plasma boundary reconstruction and divertor diagnostics on the DIII-D tokamak is reported. A good agreement with the equilibrium reconstruction and diagnostic data is achieved with respect to estimation of the spatial location of the outer strike point for the long-legged divertor plasma discharge.

Skill Acquisition and Development Issues with Predictable Badminton Feeding Routines

Badminton practice designs contain feeding routines that allow players to practice technical skills. Optimal skill acquisition and development is gained through practice simulating competitive match play rather than approaches centred around mass repetition with low levels of uncertainty. This study aimed to evaluate the biomechanical differences in twelve youth elite UK badminton players in activities with varying levels of predictability. The three experimental trials were handfeed, multifeed and match play trials. Motion capture cameras were used to record participant biomechanical data. Data analysis revealed several significant biomechanical differences between trials. Results showed that an increase in trial unpredictability led to increased depth of the forward lunge shot and a lower racket shuttlecock strike position with greater forward trunk bend. This study showed that visual search behaviour in badminton is a key component of the forward lunge shot. Predictable practice feeding routines may cause poor skill acquisition and development through maladaptive learning behaviours. Coaches are recommended to implement unpredictable feeding practice routines to simulate the visual search behaviour of competitive badminton match play to enhance skill acquisition and development in youth elite badminton players.

Biomechanical investigation of load differences on the upper extremities in dynamic hand strikes and isometric hand pushes during assembly tasks

AbstractThis study determines the effects of increasing forces on different musculoskeletal load parameters, such as muscle activity and joint movement, during assembly task‐related dynamic hand strikes and isometric push forces. Fifteen subjects (12 men and 3 women) were instructed to strike and push on a force plate in two selected conditions. In the first condition, the palmar surface of the dominant hand is oriented horizontal to the measuring surface; in the second condition, the body position is maintained, but the hand is turned 90° to allow the use of the ulnar side of the hand (fist strike position). The subjects accomplished four force levels in ascending order (i.e., 150, 250, 350, and 400 N) within the corresponding striking and pushing conditions. The extracted kinematic variables of interest were strike velocity, recoil velocity, force plate contact time, peak vertical reaction force component (force plate), force impulse, muscle activity, and maximum joint ranges of motion during the push or strike process. Differences in the results between pushes and strikes and, under certain circumstances, between fist and palm strikes were identified. Increasing push forces correlate with the muscle activity in the pectoralis and lower arm extensor muscles. The fact that, at push forces > 250 N, the subjects modify and adapt their upper body and arm posture to achieve the required force could reveal an obvious feasibility limit and explain why assembly workers tend to use their hands as a hammer.

Single Event Effect Analysis of SiGe Low Noise Amplifier

This paper analyzes the single event transient (SET) response of low noise amplifier (LNA) designed using SiGe heterojunction bipolar transistors (HBT). To verify the radiation tolerance of the proposed LNA, a total of four cascode configurations were designed. Comprehensive mixed-mode simulations were performed to evaluate the SET susceptibility of considered LNA cascode configurations, and we have analyzed how the strike parameters affect their output response. In this fact the strike position, linear energy transfer (LET), and track radius, were varied, and the resulting transients were compared for the different LNA configurations. Through this study, the potential capability of the inverse mode SiGe heterojunction bipolar transistor (HBT) in LNA radiation tolerance was confirmed for various strike operating conditions. It has been demonstrated that the single event sensitivity was reduced for LNA employing inverse mode SiGe HBT for strike device. The strike influence on the different LNA configurations response depends on strike LET, where a reduced SET variation is observed for high LET.

Numerical assessment of the new V-shape small-angle slot divertor on DIII-D

The small-angle slot (SAS) divertor of the DIII-D tokamak, and its upcoming upgrade, the V-shape small-angle slot (SAS-V) divertor, are numerically investigated using the SOLPS-ITER code package, including the effect of particle drifts, for a range of plasma density, heating power, strike point position in the slot, and for both magnetic field directions. The simulations show that the electron temperature near the strike point is reduced in SAS-V compared to SAS, for both magnetic field directions, such that SAS-V achieves divertor detachment at a lower value of the outboard mid-plane separatrix electron density. The detachment threshold is lower because the V-shape focuses recycling neutrals on the V-end, densifying and cooling the plasma in the slot. At sufficiently high density, the V-shape also reduces the radial gradient of the temperature profile at the target, which in turns reduces the radial electric field and the E × B drift velocities, further densifying and cooling the plasma in the slot and leading to detachment. The V-shape effect, however, is reduced for higher heating power. With more heating power, the detachment density increases, reducing the ionization mean free path of recycled neutrals, which therefore become less sensitive to target shape changes. This suggests that in a fusion reactor, where the heating power is high, optimization of the divertor target shape needs to be combined with other strategies to lower the detachment density, such as in-slot injection of low-Z impurities.

검도의 도구 사용 전문성에 따른 동작 예측과 대뇌 신경 활성화의 차이

Purpose: This study aimed to verify the difference between action anticipation and cortical neural activation for Kendo performance in the use of tools for professional kendo athlete and novice. Methods: Action anticipation tasks were performed on 15 kendo athletes and 15 novice group using temporal occlusion techniques. It is to accurately and quickly predict the final strike position by looking at the presented kendo strike videos (head, wrist and waist strike). In order to find out the differences in cortical neural activation according to action anticipation along with the task performance, motor-evoked potentials(MEPs) using TMS were measured. The dependent variables are predictive accuracy, response latency, and motor-evoked potentials, which are compared and analyzed between groups according to video length. Result: The analysis showed that the kendo athletes had an accurate and fast response latency compared to the novice. The comparison between groups according to video length was significantly accurate by the kendo athletes in sections 1 to 5, and was quickly performed by the kendo athletes in all video length conditions during the response latency time. In the comparison of the difference between the motor evoked potentials, kendo athletes were significantly higher in the 1st and 6th sections, and novice showed high cortical activation only in the 10th sections. Conclusion: As shown in the results, previous studies showed that kendo athletes’ excellent predictive abilities can also be seen in sports environments using tools, and behavioral predictive abilities are acquired through experience. The increased cortical activation of tool-use experts during behavior prediction demonstrated that mirror neurons do not simply follow motor matching between bodies, but also include movement of the tool, allowing mirror neural mechanisms to perform.

Erosion and redeposition patterns on entire erosion marker tiles after exposure in the first operation phase of WEST

The net erosion and deposition patterns in the inner and outer divertor of WEST were determined after different experimental campaigns (C3 and C4) of the first operational phase using ion beam analyses and scanning electron microscopy techniques. The analyses were performed on four entire tiles from inertially cooled, W-coated divertor units with an additional Mo marker coating covered with a further W coating. Strong erosion occurred at the expected location of the inner and outer strike line area with a campaign-averaged net erosion rate of >0.1 nm s−1. On the high field side of the inner strike line area, thick deposited layers were found (>10 μm; growth rate >1 nm s−1), mainly composed of B, C, O, and W. Additionally, strong arcing was observed in this region. At the end of the C4 campaign, He discharges were performed to study the He-W interaction. Although the conditions for nanotendrils, i.e. fuzz formation were fulfilled around the outer strike line position, neither nanotendrils nor He bubbles (>10 nm) were observed at this area.

Simulation Study of Single-Event Burnout in 1.5-kV 4H-SiC JTE Termination

This brief presents 2-D numerical simulation results of a single-event burnout (SEB) in a 4H-silicon carbide (SiC) junction termination extension (JTE) termination structure of a power metal-oxide-semiconductor field-effect transistor (MOSFET). Using the rated 1.5-kV JTE termination structure, the most sensitive ion's strike position to SEB is proved to be the edge of the P <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> /P <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> JTE region. Due to the severe punchthrough of the electric field, the source contact region is found to the most sensitive region to induce an SEB event. The SEB performance of the JTE termination structure with a single buffer layer or multilayer buffer is evaluated. The results show that the electric field distribution in four buffer layers (FBLs) is the most uniform to achieve the best SEB performance. Therefore, by adding an optimal FBL design to the termination region, the SEB threshold voltage can be increased to 1210 V instead of the common structure's 250 V. The SEB safe operating area of the power MOSFET with an optimal FBL can increase more than three times compared with the common one.

Entropy of Badminton Strike Positions.

The aim of the current study was twofold: (i) to investigate the distribution of the strike positions of badminton players while quantifying the corresponding standard entropy and using an alternative metric (spatial entropy) related to winning and losing points and random positions; and (ii) to evaluate the standard entropy of the receiving positions. With the datasets of 259 badminton matches, we focused on the positions of players’ strokes and the outcome of each point. First, we identified those regions of the court from which hits were most likely to be struck. Second, we computed the standard entropy of stroke positions, and then the spatial entropy, which also considers the order and clustering of the hitting locations in a two-dimensional Euclidean space. Both entropy quantifiers revealed high uncertainty in the striking position; however, specific court locations (i.e., the four corners) are preferred over the rest. When the outcome of each point was taken into account, we observed that the hitting patterns with lower entropy were associated with higher probabilities of winning points. On the contrary, players striking from more random positions were more prone to losing the points.

Three-dimensional physical model experiment of mining-induced deformation and failure characteristics of roof and floor in deep underground coal seams

Underground mining engineering causes complex changes in the three-dimensional stress near the working face of a mine, resulting in deformation and failure of the roof and floor rocks, as well as ground subsidence. To study the stress, deformation, and fracture field characteristics of the roof and floor strata due to mining, an indoor large-scale three-dimensional physical similarity model was developed. A novel method was used to simulate the mining process of coal seams. The results show that coal seam mining disrupted the original stress balance; consequently, a bearing pressure was generated in front of the working face, and a significant pressure relief state appeared in a particular area. The collapsed rock blocks of the overburden strata filled the goaf and played a supporting role, causing the overburden stress to increases again to a value close to the original rock stress. After complete mining, the overburden strata subsided, and the floor strata bulged. With an increasing vertical distance from the working face, the deformation of the rock formation gradually decreased. Evident fractured fields were formed in the surrounding rock of the goaf. In the horizontal section of the overburden rock layer, the cracks were distributed in a “rounded rectangular” shape. As the distance from the coal seam increased, the “rounded rectangular” boundary became smoother; the coverage area decreased; and the degree of crack opening and development in the plane decreased. The fractal dimensions of fractures with different overburden heights and different strike positions are calculated using the fractal geometry theory. We found that as the distance from the excavation face increased, the fractal dimensions of the fractures gradually became stable. In addition, numerical simulation methods were used to verify the correctness of the physical similarity model experiments. The research results can provide important references for the stability of deep underground projects such as coal mining process, tunnel excavation process, nuclear waste storage and other engineering stability.

An analysis of controlled detachment by seeding various impurity species in high performance scenarios on DIII-D and EAST

Experiments at DIII-D and EAST have demonstrated simultaneous high confinement, divertor detachment, and active control of detachment level, all of which are required for ITER. Comparing detachment control via Te and Jsat, it appears that Te is the most straightforward sensor to use for accessing detachment onset, while Jsat offers more precise control of degree of detachment. Based on these results, control using nitrogen seeding has so far shown the best ability to follow a target value with the low disruptivity and little to no degradation of performance when an Internal Transport Barrier (ITB) is present, but not all facilities allow its use. Neon seeding also can be paired with feedback control with low impact on core performance as long as there is no disruption, however shots with neon seeding commonly disrupted during these experiments. Argon is effective in EAST, but tends to degrade performance (by ≈10%βp) when detachment is achieved. With ideal conditions and strike point position control, data from a single Langmuir probe are an acceptable input to the control algorithm, but this simple system is easily defeated by strike point displacement comparable to the Te or Jsat scale lengths. The presence of an ITB seems to be critical to retaining core performance in detachment in these parameter ranges, as the pedestal pressure tends to decrease as a result of impurity seeding.

Analysis of Single Event Effects in Capacitor-Less 1T-DRAM Based on an InGaAs Transistor

In this work, the study of the single event effects (SEEs) in capacitor-less one-transistor dynamic random access memory (1T-DRAM) based on an indium gallium arsenide on insulator (InGaAs-OI) transistor is conducted for the first time. The electrical properties of the 90-nm device are numerically simulated to determine appropriate operation condition. The successful memory behaviors are observed due to the gate-induced drain leakage (GIDL) programming method. The impacts of different linear energy transfer (LET) values, high-energy particle (HEP) strike positions and directions, and HEP hitting moments on the memory performance are investigated via simulations. Unlike the conventional SOI device, the source and drain in 1T-DRAM cells are found to be sensitive to SEEs with a higher transient current. The single event upsets (SEUs) are found to occur only when the HEP hits the device at reading “0” state and holding state before read “0.” An increased read-out current is obtained after the HEP strike due to the GIDL- and SEE-induced accumulative floating holes. The related mechanisms are discussed in detail. These results and discussions are useful for the development of the SEE hardening of 1T-DRAM-based embedded memory for space applications in the future.

A Physics-Based Single Event Transient Pulse Width Model for CMOS VLSI Circuits

The single-event transients in MOSFETs due to heavy ion strikes introduce soft errors in sub-50 $nm$ CMOS VLSI circuits. These transients are easily captured and propagated in high-frequency CMOS VLSI circuits. The capture rate mainly depends on the single-event transient (SET) pulse width and the clock frequency of the circuits. An estimation of the SET pulse width through a physics-based model that considers the device electrostatics is necessary to predict and mitigate these soft errors in VLSI circuits. In this article, a physics-based bias-dependent model is developed to determine the SET pulse width of a double-gate (DG) CMOS inverter with the heavy-ion strike on OFF state NMOS. The output voltage perturbations due to ion strike in the CMOS inverter and the SET pulse width model are derived from the bias-dependent SET current model previously reported. The variations in the output voltage of the inverter and the pulse width obtained from the developed model for different Linear Energy Transfer (LET), supply bias, strike positions, device dimensions, and load capacitances are validated with TCAD mixed-mode simulations.

Desain dan Analisis Elemen Hingga Model Prosthetic Ankle-Foot

Foot prosthetics is one of the needs of the disabled feet as a tool for activities. The ankle prosthetic model is proposed as an alternative prosthetic model that is affordable to people with disabilities. The model is designed and analyzed to be able to withstand the average weight of a human being in the heel strike, midstance, and toe-off position and has a safe safety factor value. The research method used is the model design and model analysis consisting of preprocessing, solution, and post-processing. The analysis results showed that the greatest deformation occurred in the toe-off position of 1.52 mm when given a load of 500 N and 0.036 mm when given a moment of 5000 Nmm. The greatest strain energy was located in the forefoot area at a toe-off position of 0.6 mJ. Maximum stress also occurred at the toe-off position of 5.71 MPa. With a safety factor of 4.7, this model is categorized as safe because the stress that occurs is still below the yield strength limit of the ABS material.

High precision strike point control to support experiments in the DIII-D small angle slot divertor

Improvements in strike point control enabled tests with the new small angle slot (SAS) divertor installed at DIII-D with precision as tight as ±1 mm, barring brief perturbations from ELMs. Aside from being narrower than previous baffle structures in DIII-D, simulations indicate that performance of the SAS divertor should be very sensitive to strike point position, making the improved strike point control essential for experiments with the SAS divertor. Improved control entails regulating more divertor geometry target locations than before and setting higher gain on the strike point target. This is achieved by tasking more poloidal field (PF) shaping coils with divertor topology control, fine tuning of the coil configuration and algorithm gains, and adding regulation of the power supply common rail. The result is that although more variables are controlled, precision is better: high frequency jitter in the strike point position is lower on average compared to related discharges with standard divertor shape control.

In Vivo Assessment of Lower Limb Muscle Stress State Based on Shear Wave Elastography

This study aims to explore the possibility of assessing muscle stress state using shear wave elastography (SWE). Eight healthy males participated in the measurements, and the Young's modulus of 10 leg muscles of each participant were measured in six standard positions: lying, sitting, and four quasi-static walking postures. The contributions of each muscle in the four quasi-static walking postures were examined, and the relationship between the Young's modulus and simultaneously recorded plantar pressure was preliminarily explored for the most significant muscles. Results indicate that ICC3,1 ranges from 0.941 to 0.998, and 95% CI is in the range 0.909-0.999, CV ranges from 1.45% to 9.5%, and SEM ranges from 0.026 kPa to 0.824 kPa for all the tested muscles. This indicates that the Young's modulus of the muscles, measured by SWE, showed excellent retest reliability. In the lying and sitting positions, significant differences were observed in Young's modulus of 9 muscles with the only exception of biceps femoris (BF). In the heel strike and push off positions, strong linear relationships were found between the plantar pressure and Young's modulus of gastrocnemius medialis (GM) suggesting that muscle SWE measurement may be a good indicator of ground reaction forces. This study demonstrates that the SWE measures of the muscle Young's modulus can be used to reliably reflect the quantitative change in the stiffness of a muscle at different positions, and may also be employed to estimate the ground reaction forces and muscle stress state. Although this is a great progress in studying muscle force, it is still a great challenge to measure the Young's modulus of muscle and noninvasively evaluate the muscle force in vivo using SWE.

Comparison of selected measures of gait stability derived from center of pressure displacement signal during single and dual-task treadmill walking

Steady state gait dynamics has been examined using the measures of regularity, local dynamic stability, and variability. This study investigates the relationship between these measures under increasing cognitive loads. Participants walked on an instrumented treadmill at 1 m/s under walk only and two dual-task conditions. The secondary tasks were visuomotor cognitive games (VCG) of increasing difficulty level. The center of pressure displacement in the mediolateral direction (ML COP-D) and cognitive game performance were recorded for analysis. The following measures were calculated: (1) sample entropy (SampEn) and quantized dynamical entropy (QDE) of the ML COP-D, (2) short-term largest Lyapunov exponent (LLE) of the ML COP-D, and (3) variability of inter-stride spatio-temporal gait variables. Entropy and variability measures significantly increased from walk only to both dual-task conditions. Whereas, the short-term LLE increased only during the easy VCG task. No measure was sensitive to the difficulty level of the VCG tasks. The variability of heel strike positions in the mediolateral direction was positively correlated with SampEn and QDE. However, there were no significant correlations between the short-term LLE and either variability measures or entropy measures. These findings confirm that each of these measures is representative of a different aspect of human gait dynamics.

An Analytical Model of Single-Event Transients in Double-Gate MOSFET for Circuit Simulation

In this paper, a physics-based bias-dependent model of single-event transients (SETs) in double-gate (DG) MOSFET suitable for circuit simulation is presented. The existing approaches that use double exponential and dual double-exponential current sources to emulate these transient currents in the circuit simulators depend on the parameters extracted from TCAD device simulations. In order to capture the essential physics behind these current transients in the circuit simulations, there is a need for a physics-based bias-dependent SET current model that considers the electrostatics in the chosen device. The proposed SET current model is developed from the solution of 2-D Poisson’s equation with proper boundary conditions of DG MOSFET. It takes into account the dependence of the transient potential and drain current on linear energy transfer (LET), strike positions, drain and gate biases, device dimensions, and channel doping. The results from the model are validated with the simulation results from TCAD. The SET current model is integrated in Cadence circuit simulator and observed through simulations the voltage perturbation at the output of the CMOS inverter due to heavy ion strike on nMOS transistor in OFF state for different LETs and loads. The proposed model captures the current plateau region effect in CMOS inverter.

Experimental study on low recycling no-ELM high confinement mode in EAST

A highly reproducible spontaneous non-inductive low recycling no-ELM regime has been achieved in the EAST superconducting tokamak with the water-cooled tungsten divertor and molybdenum first wall. The salient feature is that after the L-H transition, emission intensity, divertor neutral pressure and the separatrix electron density all decrease, and the amplitude of ELMs decreases simultaneously until they disappear completely. This scenario exhibits a distinct density threshold, which is dependent on plasma current and wall condition. ELITE/NIMROD simulations indicate that the density at the foot of pedestal and ion diamagnetic effect may play a key role in the achievement of no-ELM operation; the low pedestal foot density might have a strong ion diamagnetic stabilizing effect, which can stabilize the medium-n and high-n Peeling-Ballooning modes. In order to achieve this low pedestal foot density condition, a number of techniques have been employed in EAST, i.e. through extensive lithium wall conditioning and active control of plasma configuration and strike point position. The low recycling no-ELM regime can be extended into a small ELMs regime by increasing the pedestal foot density to facilitate impurity control for long pulse operation, which has been demonstrated in EAST with a pulse length exceeding 101 s. Such a small ELMs regime provide a possible approach toward long-pulse steady-state H-mode operation in future devices.

The Value at Risk of Selling Option on Crude Oil West Texas Intermediate

The Value at Risk (VaR) of selling option on crude oil WTI has not been widely known, whereas this trade is the largest transactions in the world. This study aimed to analyze the Value at Risk (VaR) of the far out of the money (FOTM) and the in the money (ITM) strike position of selling option on crude oil WTI investment. The monthly option premium return data ranging from April 1984 to May 2017 was analyzed by the ARCH-GARCH and VaR method to get the risk of FOTM and ITM strike position. Empirical results indicate that the risk of the FOTM strike was much lower than the ITM strike positions. It meant that selecting the FOTM strike position of the selling option on crude oil WTI investment could be considered by stakeholders because its risk was much lower than the ITM strike position.