Two-layer Configuration Research Articles

Structural Lattice Topology and Material Optimization for Battery Protection in Electric Vehicles Subjected to Ground Impact Using Artificial Neural Networks and Genetic Algorithms.

A critical external interference that often appears to pose a safety issue in rechargeable energy storage systems (RESS) for electric vehicles (EV) is ground impact due to stone impingement. This study aims to propose the new concept of the sandwich for structural battery protection using a lattice structure configuration for electric vehicle applications. The protective geometry consists of two layers of a twisted-octet lattice structure. The appropriate lattice structure was selected through topology and material optimization using an artificial neural network (ANN), genetic algorithms (GA), and multi-objective optimization with technique for order of preference by similarity to ideal solution (TOPSIS) methods. The optimization variables are the lattice structure relative density, , angle, θ, and strength of the materials, . Numerical simulations were used to model the dynamic impact loading on the structures due to a conical stone mass of 0.77 kg traveling at 162 km/h. The two-layer lattice structure configuration appears to be suitable for the purposes of RESS protection. The optimum configuration for battery protection is a lattice structure with an angle of 66°, relative density of 0.8, and yield strength of 41 MPa. This optimum configuration can satisfy the safety threshold of battery-shortening deformation. Therefore, the proposed lattice structure configuration can potentially be implemented for electric vehicle applications to protect the battery from ground impact.

Impact of secondary particle size and two-layer architectures on the high-rate performance of thick electrodes in lithium-ion battery pouch cells

Increasing lithium-ion battery gravimetric energy density to > 300 Wh/kg, while simultaneously meeting a cost target of $80/kWh, is of paramount importance to increasing the driving range and affordability of electric vehicles. One way to address this goal is to reduce inactive components by increasing electrode areal capacities, but conventional thick electrode designs typically perform poorly at high discharge rates due to Li + mass transport limitations. Here we compare the rate capability and cycle life of NMC 532/graphite pouch cells made with five different thick cathode and anode designs paired together in 25 combinations. We find that using different particle sizes to structure both the cathode and anode architectures in two-layer configurations results in a 2X capacity improvement over the worst-performing combination at high discharge rates (97 vs. 46 mAh/g at 2C). These different cathode/anode designs also translate to different cycle life performance, with many cells cycled at C/2 achieving ∼80% capacity retention after 1000 cycles, and cells cycled at 2C showing different degrees of capacity fade. Overall, these results demonstrate that simple, scalable changes in electrode design can significantly improve the performance of thick electrodes for high energy density batteries. • Compared rate capability of pouch cells w/different thick cathode & anode designs. • Simple two-layer designs w/different particle sizes can be easily scaled up. • Pairing a two-layer cathode & a two-layer anode gave 2X capacity improvement at 2C. • Particle size & configuration both play important roles in determining performance. • Several electrode designs showed ≥80% capacity retention after 1000 cycles at C/2.

A Numerical Study on 3D Printed Cementitious Composites Mixes Subjected to Axial Compression

Aptly enabled by recent developments in additive manufacturing technology, the concept of functionally grading some cementitious composites to improve structural compression forms is warranted. In this work, existing concrete models available in Abaqus Finite Element (FE) packages are utilized to simulate the performance of some cementitious composites numerically and apply them to functional grading using the multi-layer approach. If yielding good agreement with the experimental results, two-layer and three-layer models case combinations are developed to study the role of layer position and volume. The optimal and sub-optimal performance of the multi-layer concrete configurations based on compressive strength and sustained strains are assessed. The results of the models suggest that layer volume and position influence the performance of multi-layer concrete. It is observed that when there exists a substantial difference in material strengths between the concrete mixes that make up the various layers of a functionally graded structure, the influence of position and of material volume are significant in a two-layer configuration. In contrast, in a three-layer configuration, layer position is of minimal effect, and volume has a significant effect only if two of the three layers are made from the same material. Thus, a multilayered design approach to compression structures can significantly improve strength and strain performance. Finally, application scenarios on some structural compression forms are shown, and their future trajectory is discussed.

Optimal configuration for photovoltaic storage system capacity in 5G base station microgrids

Base station operators deploy a large number of distributed photovoltaics to solve the problems of high energy consumption and high electricity costs of 5G base stations. In this study, the idle space of the base station’s energy storage is used to stabilize the photovoltaic output, and a photovoltaic storage system microgrid of a 5G base station is constructed. Aiming at the capacity planning problem of photovoltaic storage systems, a two-layer optimal configuration method is proposed. The inner layer optimization considers the energy sharing among the base station microgrids, combines the communication characteristics of the 5G base station and the backup power demand of the energy storage battery, and determines an economic scheduling strategy for each photovoltaic storage system with the goal of minimizing the daily operation cost of the base station microgrid. The outer model aims to minimize the annual average comprehensive revenue of the 5G base station microgrid, while considering peak clipping and valley filling, to optimize the photovoltaic storage system capacity. The CPLEX solver and a genetic algorithm were used to solve the two-layer models. Considering the construction of the 5G base station in a certain area as an example, the results showed that the proposed model can not only reduce the cost of the 5G base station operators, but also reduce the peak load of the power grid and promote the local digestion of photovoltaic power.

Hyper extended rifted margins: A computational procedure for a stretching-thinning factor estimation

Crustal extension mechanisms control rifted margin formation. During these extensional processes, the crust stretches and thins following both non-uniform and non-symmetric patterns. The modeling of main features of these processes is a relevant issue, as well as its quantification by the calculation of the stretching-thinning factors along the margins. This work presents a computational procedure for reproducing the crustal extension process due to Andersonian faulting and estimating the evolution of its extension-thinning factors. This procedure uses an algorithm based on geological hypotheses, geodynamic analysis results and kinematic relationships. The algorithm applies pure-shear extension, where stretching and thinning are based on Andersonian faulting formation. It is supposed to be applied in two-layer (upper/lower) crust configurations in two ways: a) including a new active fault; b) reactivating a previously activated fault. Kinematic relationships consider area conservation for the upper crust. The first step is the application of a crustal extension increment. This increment activates the faulting by simple shear in the upper crust and induces plastic distributed pure-shear deformation in the lower crust. This double effect generates a local thinning of both upper and lower crusts. Slip-in-fault also occurs as part of the thinning deformation. Additionally, a geodynamic analysis was carried out with an in-house developed system, based on the Finite Element Method. Coupled with advanced constitutive models, this approach is useful to reproduce stress-strain-temperature evolution during the crustal extension. Geodynamic analysis guided the definition of some improved kinematic relationships for the proposed procedure: a variable thinning zone, nonlinear thinning configurations, a variable slip/extension ratio, a shoulder uplift and out-of-section fault pivot. The procedure was applied to reproduce part of a crustal stretch of a hyper extended margin due to Andersonian faulting, estimating its thinning and extension factors. The results show that this procedure is able to qualitatively reproduce crustal extensional configurations.

Two-Layer Collaborative Optimization Configuration Method for CCHP System with Wind-Solar-Storage

Two-Layer Collaborative Optimization Configuration Method for CCHP System with Wind-Solar-Storage

Development of a lumped-parameter code for efficient assessment of in-vessel melt retention strategy of LWRs

Motivated by efficient assessment of the in-vessel retention (IVR) strategy employed in some designs of light water reactors, a lumped-parameter code named as transIVR was developed in the present study, which has the features as (i) quick estimates of transient one- and two-layer melt pool heat transfer with reasonable accuracies; and (ii) two-dimensional representation of heat conduction in the reactor pressure vessel wall, facilitating the coupled thermo-mechanical analysis of the reactor pressure vessel under thermal loads. The transIVR code was first benchmarked against the UCSB FIBS case of two-layer configuration and then validated against the LIVE-7V experiment. Both cases showed good predictions in the IVR-interested parameters like the heat flux profile, residual wall thickness and energy split. It indicates the code's capability in predicting two-layer and transient melt pool heat transfers, respectively. Finally, the code was coupled with ANSYS Mechanical for the efficient assessment of vessel integrity. Good results were achieved in the validation against the vessel failure experiment FOREVER-EC2. Hence, the transIVR code is an efficient tool suitable to address related safety concerns of light water reactors, including IVR efficacy and vessel integrity (with its coupling to mechanical solvers).

Investigation of the pressure vessel lower head potential failure under IVR-ERVC condition during a severe accident scenario in APR1400 reactors

In the event of a core meltdown in a high-power reactor, the integrity of the reactor pressure vessel is presumably protected by severe accident mitigation systems such as in-vessel retention external reactor vessel cooling (IVR-ERVC). However, in the late phase of the accident, two possible locations on the RPV are prone to failure: the location of the focusing effect and location of in-core instrument penetration. These two potential points of damage in the RPV are investigated in this study. A numerical model for the prediction of the natural convection, melting, and solidification processes for IVR-ERVC is presented. The model is based on the enthalpy-porosity approach with an extension for continuous liquid fraction function. The model is implemented in open-source field operation and manipulation (OpenFOAM) computational fluid dynamic code to produce a new solver which is based on the combination of conjugate heat transfer solver and buoyant-driven natural convection solver and the new solver is validated against the melting Gallium experimental test, in-core instrumentation failure experimental test, and BALI experimental test. This numerical model is applied for the investigation of the RPV rupture at the location of the focusing effect and in-core instrumentation penetrations. Severe ablations of the cladding and the weld materials are observed at a heat load of about ~1800 K which is expected to lead to the ejection of the penetration tubes if the force holding the penetration tube in place is lower than the force exerted by the system pressure. Subsequently, a two-layer IVR configuration is assessed and the integrity of the RPV is found not to be compromised under external reactor vessel cooling. However, in the case of a boiling crisis, the temperature of the ex-vessel wall is expected to rise quickly and this is simulated by increasing the ex-vessel wall temperature. The RPV is found to fail near the beltline due to a phenomenon known as focusing effect when the ex-vessel wall temperature rises above 1200 K.

A modular microfluidic system based on a multilayered configuration to generate large-scale perfusable microvascular networks

The vascular network of the circulatory system plays a vital role in maintaining homeostasis in the human body. In this paper, a novel modular microfluidic system with a vertical two-layered configuration is developed to generate large-scale perfused microvascular networks in vitro. The two-layer polydimethylsiloxane (PDMS) configuration allows the tissue chambers and medium channels not only to be designed and fabricated independently but also to be aligned and bonded accordingly. This method can produce a modular microfluidic system that has high flexibility and scalability to design an integrated platform with multiple perfused vascularized tissues with high densities. The medium channel was designed with a rhombic shape and fabricated to be semiclosed to form a capillary burst valve in the vertical direction, serving as the interface between the medium channels and tissue chambers. Angiogenesis and anastomosis at the vertical interface were successfully achieved by using different combinations of tissue chambers and medium channels. Various large-scale microvascular networks were generated and quantified in terms of vessel length and density. Minimal leakage of the perfused 70-kDa FITC-dextran confirmed the lumenization of the microvascular networks and the formation of tight vertical interconnections between the microvascular networks and medium channels in different structural layers. This platform enables the culturing of interconnected, large-scale perfused vascularized tissue networks with high density and scalability for a wide range of multiorgan-on-a-chip applications, including basic biological studies and drug screening.

Understanding Uncertainty of Snow Radiative Transfer Modeling Within a Mixed Deciduous and Evergreen Forest

Satellite-based passive microwave observations provide the best available continuous observational estimates of global snow water storage due to their broad geographic footprint and low sensitivity to clouds and precipitation. However, these observations are subject to substantial uncertainty due to the complex radiative properties of snow and from interference in forested areas. Physical radiative transfer models can be leveraged to improve the fidelity of these observations and as a data-assimilation tool. In this article, the Dense Media Radiative Transfer model with Multiple Layers (DMRT-ML) is used to simulate snow brightness temperatures from data collected from snow pits excavated during a two-day-long field study performed a temperate forest in the Northeast United States. The simulations are evaluated against surface-based radiometer observations collected at the snow pits. The DMRT-ML is configured with varying complexity to determine the snowpack characteristics most essential toward simulating brightness temperature within a temperate forest with complicated snow stratigraphy. In general, the single-layer configurations were not sufficiently complex to accurately simulate snow brightness temperature without significant tuning. The most accurate simulation was a two-layer configuration with a prescribed ice layer separating the snow layers. This simulation had a root-mean-square error $<; $15 K for the 37-GHz frequency. More complicated snowpack stratigraphy configurations did not substantively improve the results over the two-layer model configuration. The DMRT-ML was also used to examine differences between redundant datasets of density and grain size. It was determined that similar snow data collection and radiative transfer model configuration techniques are critical to ensure cross-study comparability.

Multi-Layer Transient Heat Conduction Involving Perfectly-Conducting Solids

Boundary conditions of high kinds (fourth and sixth kind) as defined by Carslaw and Jaeger are used in this work to model the thermal behavior of perfect conductors when involved in multi-layer transient heat conduction problems. In detail, two- and three-layer configurations are analyzed. In the former, a thin layer modeled as a lumped body is subject to a surface heat flux on the front side while it is in perfect (fourth kind) or in imperfect (sixth kind) thermal contact with a semi-infinite or finite body on the back side. When dealing with a semi-infinite body in imperfect contact, the temperature solution is derived by means of the Laplace transform method. Green’s function approach is also used but for solving the companion case of a finite body in perfect contact with the thin film. In the latter, a thin layer with internal heat generation is located between two semi-infinite or finite bodies in perfect/imperfect contact. For the sake of thermal symmetry, such a three-layer structure reduces to a two-layer configuration. Results are given in both tabular and graphical forms and show the effect of heat capacity and thermal resistance on the temperature distribution of conductive layers.

Influence of pycnocline on settling behaviour of non-spherical particle and wake evolution

Settling of non-spherical particles in a stratified fluid exhibits complex dynamics in a low-to-moderate inertia regime. Although this process is involved in a wide variety of phenomena in natural fluid systems, its fundamental mechanisms are still unexplored. Understanding of particle settling in microscale is particularly important to explain challenging problems associated with ecological and biogeochemical processes in the ocean due to the delayed settling of particulate matter at pycnoclines. Here, I explore interactions between disk-shaped particles and a stratified fluid with a density transition. By laboratory experiments, I demonstrate that the settling dynamics of the disk crossing a density transition are tightly coupled with the wake structure evolution, and I observe for the first time in a two-layer ambient configuration a bell-shaped structure that forms on a jet after the wake has detached from the particle. Furthermore, I identify hydrodynamic conditions for the variations of settling velocity and particle orientation instabilities. These findings shed light on particle settling mechanisms necessary to explain dynamics of marine particles such as plankton, faecal pellets, and microplastics and may improve the estimation methods of sedimentation processes in various areas of earth sciences and engineering.

Snow wetness retrieved from close-range L-band radiometry in the western Greenland ablation zone

AbstractClose-range (CR) L-band radiometry and quasi-simultaneous in situ snow characterizations were conducted in May 2019 at the Swiss Camp research site in the ablation zone of the western Greenland ice sheet. Snow liquid-water and its melt/refreeze are retrieved from microwave antenna temperatures measured with the ground-based L-band radiometer ELBARA-III. The emission model (EM) used in the retrieval is a two-layer configuration of the ‘L-Band Specific Microwave Emission Model of Layered Snowpack’. Consistent snow wetness retrievals were achieved from both single- and multi-angle CR observations of L-band antenna temperatures. This suggests that multi-angle observation is not a pre-requisite for snow wetness retrieval. Therefore, in addition to soil moisture and ocean salinity (SMOS) multi-angle measurements, snow wetness can be estimated from spaceborne L-band brightness temperatures measured at a single observation angle, such as from NASA's SMAP satellite. Our results provide partial validation of a recently presented snow wetness retrieval approach based on the same EM and applied over Greenland using multi-angle SMOS brightness temperatures. Agreement between measured CR antenna temperatures and SMOS brightness temperatures is found to be within the 95% confidence intervals of ELBARA-III and SMOS measurement uncertainties. Our measurements confirm the modeled response of antenna temperatures to diurnal variations of snow wetness.

Study on the two-layer optimal configuration strategy of wind abandoning and absorption in CHP micro-grid

In order to solve the problem of wind abandoning for micro-grid in the heating season. Adding electric boiler and thermal storage device to micro-grid and using configuration strategy is an effective way, the effective configuration scheme is also very important to it. A two-layer model optimization method that introduces scheduling in configuration is proposed, the models and constraints of the main units in the micro-grid are given, the upper layer aims to minimize the sum of the total operation cost and configuration and maintenance cost of the micro-grid during the heating period, the lower layer aims to minimize the integrated operation cost of the 24-hour micro-grid. Simulation results show that, the proposed method can effectively reduce the operation cost and wind abandoning power of micro-grid, the optimal configuration scheme is obtained.

Building superior lighting properties for WLEDs utilizing two-layered remote phosphor configurations

Abstract The remote phosphor structure produces higher luminous flux but delivers poorer color quality than the conformal or in-cup phosphor structure. To eliminate this weakness, researchers have attempted to improve the chromatic properties of remote phosphor package. This study tends to enhance lighting features for WLEDs including color quality and luminous flux in general or color rendering index (CRI) and color quality scale (CQS) in particular by applying dual-layer remote phosphor structure. In the simulation section, we utilize two identical LEDs that only differ in correlated color temperature values which are 6600 K and 7700 K. The study offers an idea of placing a yellow-green phosphor layer SrBaSiO4:Eu2+ or a red phosphor layer SrwFxByOz:Eu2+,Sm2+ on the yellow phosphor layer YAG:Ce3+ and then modifying the concentrations of SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ to the suitable values to improve the color quality and lumen output of WLEDs. The results show that red phosphor layer SrwFxByOz:Eu2+,Sm2+ has a significant influence on CRI and CQS improvement. Particularly, the increase of SrwFxByOz:Eu2+,Sm2+ concentration leads to increased CRI and CQS because the red light component increases in WLEDs. On the other hand, the green phosphor layer SrBaSiO4:Eu2+ only brings benefit to the luminous flux. However, the WLEDs’ luminous flux and color quality drop sharply, when SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ concentrations rise extremely, which is verified based on the Mie-scattering theory and the Lambert-Beer law. In short, the article provides general knowledge and primary information for the production of higher-quality WLEDs.

On-Chip Inductor in 0.18-μm CMOS for Low-Cost Fully Integrated Contactless Powered Sensors

Contactless sensors with CMOS on-chip antennas use only the top thick metal for the polarization antenna due to the low inductance contribution of the bottom (thin) CMOS metals adding only resistance to the antenna. In this letter, a two-layer inductor (thick top metal layer inductor in series with the bottom thin four-layer metal inductor) configuration was proposed for wireless polarization (by electromagnetic induction). The design proposed was simulated and fabricated in a 0.18- $\mu \text{m}$ CMOS process. The on-chip inductor powers a chip with a 1-mW load at a distance of 2 mm coupled with an external wireless power transmitter at 13.5 MHz with a 30-dBm output. The two-layer inductor configuration reduces the area required for the on-chip inductor by 38% and increases the on-chip inductor quality factor by 25% compared with a single-layer configuration, thus reducing the cost of fabricating fully integrated contactless sensors using only CMOS technologies.

A comparative study among WS2, MoS2 and graphene based surface plasmon resonance (SPR) sensor

In the present paper, we propose a new design of surface plasmon resonance (SPR) sensor having better performance parameters by employing the well-known transfer matrix method. The proposed SPR sensor is comprised of BK-7 prism-ZnO-Ag-BaTiO3-Transition metal dichalcogenides (TMDCs, mainly WS2 and MoS2)/Graphene. A comparison is made among their performance parameters i.e. sensitivity, detection accuracy, quality parameter with other traditional reported SPR sensor. We have also analysed full width at half maxima (FWHM) and electric field intensity enhancement factor (EFIEF) for the proposed SPR sensor. On comparison, it is found that the proposed SPR sensor with monolayer WS2 configuration has better sensitivity of 180°/RIU as compared to monolayer MoS2 and graphene which are 174°/RIU and 157°/RIU respectively. However, the proposed SPR sensor with graphene layer shows small FWHM, higher quality parameter and detection accuracy. We have found that maximum sensitivity of 2350/RIU corresponds to the two-layer WS2 configuration. Our proposed SPR sensor shows better performance as compared to the other reported works.

Lenslets combination optimal design of the segmented planar image detector for electro-optical reconnaissance

Segmented planar image detector for electro-optical reconnaissance (SPIDER) is a new type of lightweight and high-resolution computational imaging system that has applications in fields such as remote sensing terrain exploration, high precision military detection, and remote environmental monitoring. Currently, the lens combination methods used in the SPIDER system misses a large amount of the spatial-frequency information detected by each spoke’s lens array. The SPIDER imaging principle was analyzed with a particular focus on understanding the effect of the lenslets combination method on image quality. To optimize the quality of reconstructed images, we have proposed a pseudo two-layer parity configuration. To compare the quality of image restoration using the pseudo two-layer parity combination methods with previously existing methods, the entire imaging process was numerically simulated and the peak signal-to-noise ratio of each reconstructed image was estimated. The simulation demonstrated that the reconstructed image obtained using the pseudo two-layer parity combination was more similar to the original image and exhibited a higher image quality than the images reconstructed using other methods. These results indicate that the optical structure of the SPIDER system can be optimized by implementing the pseudo two-layer parity aperture combination method and this provides theoretical support for the further development of the SPIDER system.

Coupled convection and internal gravity waves excited in water around its density maximum at 4°C

Coupled mixed convective and stratified systems are common in natural flows. To study experimentally the associated dynamics, we use a singular property of water: its non-linear equation of state is characterised by a maximum density close to $4^{\circ}$C. By heating the top of a tank at $35^{\circ}$C and cooling the bottom at $0^{\circ}$C, a two-layer configuration spontaneously appears. The convective motion in the bottom layer consists mostly of a large-scale circulation and rising cold plumes. This turbulent flow generates propagating internal gravity waves in the upper stably-stratified layer. PIV measurements are performed and spectral characteristics of the convection and internal gravity waves are presented. An horizontal large-scale reversing flow in the stratified layer is observed which is viscously driven by a third, intermediate layer. This buffer layer is located between the convective and stratified layers and is thermally coupled with the convective one, hence sustaining a strong horizontal shear. Three dimensional direct numerical simulations with geometry and physical parameters close to the experimental ones corroborate our experimental results.

Linear instability in two-layer channel flow due to double-diffusive phenomenon

The linear stability characteristics of a pressure-driven channel flow of two miscible fluids flowing in a layered manner are investigated in the presence of two scalar components diffusing at different rates [double-diffusive (DD) phenomenon]. The fluids are assumed to have the same density but different viscosities. The parameters varied are the Reynolds number, Schmidt number, and thickness of the bottom layer. It is observed that the linear stability behavior in the presence of the DD effect is strikingly different from that observed in the single-component (SC) system. While the SC two-layer configuration is stable, the DD two-layer flow becomes unstable at low and moderate Reynolds numbers. It is found that increasing the diffusivity ratio of the faster to the slower diffusing scalar destabilizes the system. A region of instability distinct from that of the Tollmien–Schlichting (TS) mode appears for some combinations of the log-mobility ratios of the slower and faster diffusing scalars. This unstable region grows as the diffusivity ratio increases and the thickness of the bottom layer decreases. For a constant diffusivity ratio, decreasing the Schmidt number of the slower diffusing scalar also increases the region of instability. An energy budget analysis is conducted to understand the underlying mechanism of this instability. Two mechanisms, namely, (i) the rate of energy transfer from the basic flow to the disturbance and (ii) the disturbance energy due to mean viscosity gradient, are found to be the significant contributors to the increase in the rate of change of the disturbance kinetic energy.