Reliability Analysis of High Concrete-Face Rockfill Dams and Study of Seismic Performance of Earthquake-Resistant Measures Based on Stochastic Dynamic Analysis

The randomness of earthquake excitation has a significant impact on the seismic performance of high earth-rock dams. In this paper, the seismic performance of geosynthetic-reinforced soil structures (GRSS) of high concrete face rockfill dams (CFRDs) is evaluated from the stochastic perspective. Multiple groups of seismic ground motions are generated based on spectral expression-random function non-stationary model. Taking Gushui CFRD as an example, this study calculates the failure probability of each damage level of non-reinforce slopes and reinforce slopes based on generalized probability density evolution method (GPDEM) and reliability analysis is presented though multiple evaluation indicators. The result shows that GRSS can reduce the mild damage of CFRDs during earthquake and restrain the moderate and severe damage. The influence of vertical spacing and length of GRSS on the seismic performance is obtained, which provides a reference for the seismic design and risk analysis of CFRDs.

A Study of Variable Cell Spacings to the Heat Transfer Efficiency of Air-Cooling Battery Thermal Management System

The air-cooling battery thermal management system has been widely adopted as the thermal management device for power accumulators on electric vehicles nowadays. To improve the system heat transfer coefficient with the minimum rise in cost, this study modified conventional rectangular cell arrangements for 21,700 cylindrical cell battery packs with two approaches: 1. increase the vertical spacings; 2. convert constant vertical spacings to gradient vertical spacings. The results show that smaller vertical spacings are beneficial to the overall cooling performances of the constant vertical spacings designs at almost all flow rates. The gradient vertical spacing design with larger spacing could deliver better temperature uniformity, while the one with smaller spacings could suppress the maximum temperature more efficiently at higher flow rates. However, the total battery pack volume of Design 7 (the largest gradient vertical spacing design) is 7.5% larger than the conventional design.

JOANNE: Joint dropsonde Observations of the Atmosphere in tropical North atlaNtic meso-scale Environments

As part of the EUREC4A field campaign which took place over the tropical North Atlantic during January–February 2020, 1215 dropsondes from the HALO and WP-3D aircraft were deployed through 26 flights to characterize the thermodynamic and dynamic environment of clouds in the trade-wind regions. We present JOANNE (Joint dropsonde Observations of the Atmosphere in tropical North atlaNtic meso-scale Environments), the dataset that contains these dropsonde measurements and the products derived from them. Along with the raw measurement profiles and basic post-processing of pressure, temperature, relative humidity and horizontal winds, the dataset also includes a homogenized and gridded dataset with 10 m vertical spacing. The gridded data are used as a basis for deriving diagnostics of the area-averaged mesoscale circulation properties such as divergence, vorticity, vertical velocity and gradient terms, making use of sondes dropped at regular intervals along a circular flight path. A total of 85 such circles, ∼ 222 km in diameter, were flown during EUREC4A. We describe the sampling strategy for dropsonde measurements during EUREC4A, the quality control for the data, the methods of estimation of additional products from the measurements and the different post-processed levels of the dataset. The dataset is publicly available (https://doi.org/10.25326/246, George et al., 2021b) as is the software used to create it (https://doi.org/10.5281/zenodo.4746312, George, 2021).

Optimization of geometric parameters of soil nailing using response surface methodology

Optimization of parameters of soil nailing is an important task in reinforcement soil problems. This paper focuses on the effect of nail geometric parameters on soil nailed wall analysis and identifies which factors that most affect their stability and cost using response surface methodology (RSM). RSM has been chosen to achieve an optimum combination of the soil nailing wall design. The influence of three factors has been considered; it included nail length, its inclination, and vertical spacing between nails. After a finite element analysis to model and perform the soil nailing simulations, a Box–Behnken design was applied, based on a set of experiments using various combinations. For this purpose, 15 runs were conducted to analyze tested parameters and to determine their interactions. The analysis of variance (ANOVA) and contour lines plots were investigated, and therefore, the most important parameters affecting the safety factor and the cost were identified. From the goodness-of-fit analyses of the model and the illustrative example, the proposed regression model provides a reasonably good estimate of the overall safety factor for soil nail walls and their cost. The results obtained from this study showed that RSM is an efficient and effective tool to identify the optimal combination, and it emerges that the safety factor and cost are most influenced by nail length and vertical spacing.

Merging of Horizontally and Vertically Separated Small-Scale Buoyant Flames

The purpose of this study was to investigate the merging behavior of small-scale buoyant flames that might be representative of flames from a leaf in a shrub. Zirconia felt pads soaked in n-heptane were suspended on thin rods and spaced both horizontally and vertically. Time-dependent video images from flames from two-pad and three-pad configurations were analyzed to determine merging probability, combined flame characteristics (height, area, and width), and changes in burn time. Correlations of these combined flame characteristics were developed based on horizontal and vertical spacing between the pads. Merging probability correlated with an exponential function that was quadratic in horizontal and/or vertical spacing. Flame heights corrected for vertical inter-pad spacing showed a maximum increase of 50% over single flame heights, and were correlated with an exponential decay function. Flame areas increased by a maximum of 34%, but on average were relatively constant. Corrected flame widths for the merged flames increased by as much as 55% in some configurations, but decreased by up to 73% in other configurations. Burn times for upper pads decreased when there was no horizontal spacing. The limited flame growth observed in these non-overlapping configurations in the horizontal dimension imply that overlapping configurations seem to be necessary for significant flame growth.

Design and Experiment of the Automatic Laying System for Rice Seedling Tray

In the process of raising rice seedlings, it is necessary to manually place the seedling trays one by one in the seedling field, which is labor intensive and low in efficiency. In order to solve this problem, according to the actual conditions of the rice seedling field, this paper designs and develops an automatic rice tray laying system, which consists of a gantry truss moving unit, a tray laying trolley unit, a tray laying mechanism unit and a sensor control unit. Through the movement and timing coordination of the cams in the laying mechanism unit, four actions of holding, clamping, laying and restoring are designed to realize the orderly and automatic laying of the stacked seedling trays one by one. In order to meet the agronomic requirements of the horizontal and vertical spacing of seeding trays, especially the efficiency of rice tray laying, the control strategies of the key parts of the system were simulated, selected and optimized. For the longitudinal movement of the gantry truss, the cross-coupling control strategy is adopted to realize the detection and compensation correction of the synchronous position error of the two driving motors. As for the drive motor of the laying trolley and the laying mechanism, the optimized master-slave follow-up control method is adopted to improve the efficiency and accuracy. The results of simulation and field experiment show that when the tray trolley moves on the gantry truss at the speed of 7.5 cm/s, the gantry truss moves at the speed of 35 cm/s in the longitudinal direction, and when the height of the tray laying mechanism is 100 mm from the ground and the motor speed is 375 rpm, the horizontal spacing of the tray can be maintained at 25 ± 5 mm and the vertical spacing at 15 ± 5 mm. The efficiency of tray laying can be increased by 35.7%, up to 380 trays/h, meeting the technical requirements of mechanized field tray laying.

Security-Enhanced 3D Data Encryption Using a Degradable pH-Responsive Hydrogel

Based on degradable pH-responsive hydrogel, we report on an enhanced three-dimensional data encryption security technique in which a pH value is used for information manipulation. Featuring three types of states upon the pH value variation, namely, shrinkage, expansion and degradation, the hydrogel renders a limited pH value window as the “key” for information decryption. The pH-dependent shrinkage-to-expansion conversion of the hydrogel leads to a threshold pH value for retrieving the recorded data, whilst the degradability of the hydrogel, which can be tuned by adjusting the composition ratio of PEGDA/AAc, gives rise to a second threshold pH value for irreversibly sabotaging the retrieved data. Pre-doping silver ions in the hydrogel facilitates explicit recording and reading of binary data in forms of three-dimensional silver patterns through photoreduction and scattering, respectively, with a femtosecond laser. By accurately matching the vertical spacing of the encoded silver nanopatterns with the diffraction-limited focal depth of the decryption microscope, we can tune the pH value to encrypt and retrieve information recorded in layers and set a critical pH value to smash encoded information, which proves a highly secured 3D data encoding protocol. This strategy can effectively enrich data encryption techniques, vastly enhancing data security within unattained chemical dimensions.

Analysis of the Deformation Characteristics of Vertically Reinforced Subgrades to Address Land Shortage in Railroad Construction

Vertically reinforced subgrade (VRS) the construction of which involves building backfills first and then facing walls was developed for the railroad construction in areas with land shortages, such as civil areas. VRS minimizes the land use during railroad construction and operation. It also reduces residual settlement during railway operation by virtue of its staged construction process. In this study, numerical analysis was performed to quantitatively evaluate the deformation characteristics of VRS, such as surface settlement and horizontal deformation, during the construction and operation of railroads. It was confirmed that VRS with 40 cm of vertical spacing and a reinforcement short length of 0.35H complies with the limit of residual settlement (30 mm) and horizontal deformation (less than 0.03H) for concrete slab tracks, even in the most unfavorable conditions.

Bidirectional Electromagnetically Induced Transparency Based on Coupling of Magnetic Dipole Modes in Amorphous Silicon Metasurface

A bidirectional electromagnetically induced transparency (EIT) arising from coupling of magnetic dipole modes is demonstrated numerically and experimentally based on nanoscale a-Si cuboid-bar metasurface. Analyzed by the finite-difference time-domain (FDTD) Solutions, both the bright and dark magnetic dipole mode is excited in the cuboid, while only the dark magnetic dipole mode is excited in the bar. By breaking the symmetry of the cuboid-bar structure, the destructive interference between bright and dark magnetic dipole modes is induced, resulting in the bidirectional EIT phenomenon. The position and amplitude of simulated EIT peak is adjusted by the vertical spacing and horizontal spacing. The EIT metasurface was fabricated by Electron-Beam Lithography and deep silicon etching technique on the a-Si film deposited by Plasma-Enhanced Chemical Vapor Deposition. Measured by a convergent spectrometer, the fabricated sample achieved a bidirectional EIT peak with transmission up to 65% and 63% under forward and backward incidence, respectively. Due to the enhanced magnetic field induced by the magnetic dipole resonance, the fabricated bidirectional EIT metasurface provides a potential way for magnetic sensing and magnetic nonlinearity.