Edge-localized mode (ELM) suppression by resonant magnetic perturbations (RMPs) generally occurs over very narrow ranges of the plasma current (or magnetic safety factor q95 ) in the DIII-D tokamak. ...However, wide q 95 ranges of ELM suppression are needed for the safety and operational flexibility of ITER and future reactors. In DIII-D ITER similar shape plasmas with n = 3 RMPs, the range of q95 for ELM suppression is found to increase with decreasing electron density. Nonlinear two-fluid MHD simulations reproduce the observed q95 windows of ELM suppression and the dependence on plasma density, based on the conditions for resonant field penetration at the top of the pedestal. When the RMP amplitude is close to the threshold for resonant field penetration, only narrow isolated magnetic islands form near the top of the pedestal, leading to narrow q95 windows of ELM suppression. However, as the threshold for field penetration decreases with decreasing density, resonant field penetration can take place over a wider range of q95. For sufficiently low density (penetration threshold) multiple magnetic islands form near the top of the pedestal giving rise to continuous q95 windows of ELM suppression. The model predicts that wide q95 windows of ELM suppression can be achieved at substantially higher pedestal pressure in DIII-D by shifting to higher toroidal mode number ( n = 4 ) RMPs.
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Reliability-based design of rockfall passive systems height Marchelli, Maddalena; De Biagi, Valerio; Peila, Daniele
International journal of rock mechanics and mining sciences (Oxford, England : 1997),
March 2021, 2021-03-00, 20210301, Volume:
139
Journal Article
Peer reviewed
Passive structural systems against rockfalls, as net fences and embankments, are among the most effective mitigation measures for high energy events. Although largely adopted, the design of these ...systems has not been codified yet. A profitable time-dependent reliability approach has been recently introduced by the Authors, accounting for different possible probability distributions of velocity, mass, and height of the impacting block. Two failure modes were considered, related to the energy absorption capacity and the intercepting height of the systems. As the current design approach is based on partial safety factors, several sensitivity analyses are herein presented, with a particular focus on the height, firstly to define a suitable combination of equivalent partial safety factors, and, secondly, to investigate the parameters related to the geometry and the kinematics of the block which mostly affect the factors. Moreover, for a given failure probability, two shallow neural network were built, one for each failure mode, considering the possible range of all the input parameters, creating thus two input-output relationships that can be used to evaluate the partial safety factors for the height and the energy.
The Food Quality Protection Act of 1996, or FQPA, required the Environmental Protection Agency to set allowable levels for pesticides in a way that would "ensure that there is a reasonable certainty ...that no harm will result to infants and children from aggregate exposure to the pesticide chemical residue." The act stipulated that an additional tenfold margin of safety for pesticide risk assessments shall be applied to account for pre- and postnatal toxicity and for any data gaps regarding pesticide exposure and toxicity, unless there are reliable data to demonstrate that a different margin would be safe for infants and children.
To examine the implementation of the FQPA-mandated additional margin of safety, this analysis reviews 59 pesticide risk assessments published by the EPA between 2011 and 2019. The list includes 12 pesticides used in the largest amount in the U.S.; a group of 35 pesticides detected on fruits and vegetables; and 12 organophosphate pesticides. For the non-organophosphate pesticides reviewed here, the EPA applied an additional children's health safety factor in 13% of acute dietary exposure scenarios and 12% of chronic dietary exposure scenarios. For incidental oral, dermal and inhalation exposures, additional FQPA factors were applied for 15, 31, and 41%, respectively, of the non-organophosphate pesticides, primarily due to data uncertainties. For the organophosphate pesticides as a group, a tenfold children's health safety factor was proposed in 2015. Notably, in 2017 that decision was reversed for chlorpyrifos.
For the majority of pesticides reviewed in this study, the EPA did not apply an additional FQPA safety factor, missing an opportunity to fully use the FQPA authority for protecting children's health.
Structural health assessments are essential for infrastructure. By using an autonomous panorama vision‐based inspection system, the limitations of the human cost and safety factors of previously ...time‐consuming tasks have been overcome. The main damage detection challenges to panorama images are (1) the lack of annotated panorama defect image data, (2) detection in high‐resolution images, and (3) the inherent distortion disturbance for panorama images. In this paper, a new PAnoramic surface damage DEtection Network (PADENet) is presented to solve the challenges by (a) using an unmanned aerial vehicle to capture panoramic images and a distorted panoramic augmentation method to expand the panoramic dataset, (b) employing the proposed multiple projection methods to process high‐resolution images, and (c) modifying the faster region‐based convolutional neural network and training via transfer learning on VGG‐16, which improves the precision for detecting multiple types of damage in distortion. The results show that the proposed method is optimal for surface damage detection.
•The proposed method can classify and predict occupational accident types using a random forest (RF) model.•We presented key construction safety factors that affect the occupational accident types in ...Korea using feature importance.•The accuracy score of the RF model was obtained as 71.3%.•It will give a significant contribution to safety management of both practitioners and researchers in the construction industry.
Although industrial accident rates are gradually decreasing in Korea, the construction industry's accident rate is still higher compared with other industries. Human errors, mentally unstable workers, insufficient safety training, and safety policy affect the occurrence of construction accidents. Owing to the characteristics of this industry, occupational accident types, such as fall from height, collision with objects, rollover, and those due to falling objects, can be related to the weather data.
Therefore, to reduce and prevent occupational injury, it is necessary to classify and predict occupational accident types in detail. In this study, we built a model to classify and predict occupational accident types using a random forest (RF). We extracted important factors that affect the occupational accident types at construction sites using feature importance, and we analyzed the relationship between these factors and occupational accident types. The accuracy score of the RF model was obtained as 71.3%, and we presented key construction safety factors considering the feature importance. For future research, we will collect data and develop models to predict occupational accident types in real-time. Real-time construction accident prediction research will reduce accident at construction sites.
Majority existing organic composite phase change materials (CPCMs) are flammable that result in thermal hazards such as fire and explosions in battery modules. Furthermore, the performance of ...PCM-based battery modules in extreme conditions like thermal runaway has not been studied adequately. In this study, a tubular CPCM-cell structure is designed using physically flame-retardant-modified CPCMs, and a series of experiments on the CPCMs with/without real cells is conducted with calorimeter tests and SEM analysis on morphology structure. First, the calorimeter tests and comparison on the heat release rate (HRR) are conducted on the CPCMs with and without flame retardant additives. Results show that the addition of Al(OH)3 reduced the HRR from 242.5 to 204.4 kW/m2 with 15 wt% additives. Besides, the analysis of the mitigating performances of structure-enhanced tubular module and traditional cuboid module with real batteries is conducted. A factor of safety (FOS) parameter is defined to evaluate the safety degree of thermal runaway domino with energy density. The FOS of blank, CPCM–0C, and CPCM–15C modules are 0, 3.59, and 16.67, respectively, while that of CPCM-15T reaches 21.01, indicating a significant improvement on mitigating effects by structure enhancement compared to adding flame retardant additives. This study brings novelty in the design of PCM-based battery modules, particularly from the thermal safety prospect.
•An optimized tubular module using modified CPCM is designed to reduce hazard risk.•Bottleneck issue is solved by structure enhancement without reducing energy density.•Effect of flame retardant additives on thermal hazards is tested with/without cells.•Mitigation of tubular unit with air-flow-channel on heat propagation is tested.•Evaluation of battery modules are conducted from two aspects simultaneously.
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