Grid Thickness Research Articles

Flexural performance of BFRP grid–ECC in strengthening damaged RC beams

An innovative strengthening method combining basalt fiber reinforced polymer (BFRP) grid and engineered cementitious composites (ECC) is proposed to address the shortcomings in the durability of bonded connections with FRP materials and concrete materials. In this method, the BFRP grid wraps around the original damaged reinforced concrete (RC) structure, and the outer layer is cast with ECC, which mainly acts as a binder to enhance the bonding effect. In order to verify the effectiveness of the proposed method, 10 specimens were prepared and their flexural characteristics and load carrying capacity were investigated. Some factors that may affect the effectiveness of strengthening, such as the degree of initial damage (expressed in terms of different initial damage loads), the thickness of the BFRP grid, and the method of reinforcement, were considered in the experiments. The experimental results show that the proposed strengthening method can significantly improve the bending capacity of the damaged RC beams (7%~43%) without significantly enlarging the cross-section and self-weight. In addition, during the loading tests, localized peeling between the BFRP grid–ECC layer and the RC beams occurs at the time of damage, meanwhile the BFRP grid breaks. This suggests that it is feasible to enhance the bond between BFRP grid and RC by using ECC layer instead of other materials as the bonding agents. The proposed strengthening method has a promising application in strengthening old/residual bridges. In addition, a simple formula for predicting the flexural load capacity of the strengthened beams is derived. The ratio of the proposed formula to test value is between 0.853 and 1.304. The flexural load capacity predicted by the proposed formula is in better agreement with the experimental results.

Experimental study on the flexural performance of FRP grid-reinforced ultra-high-performance concrete I-beams with different steel fiber contents

To adapt to harsh engineering environments, the use of structural components with fiber-reinforced polymer (FRP) grid-reinforced ultra-high-performance concrete (UHPC) is considered a new development trend. Twelve FRP grid-reinforced UHPC I-beams are fabricated to investigate the effects of the thicknesses of FRP grids (0 mm, 1 mm, 3 mm, and 5 mm) and the steel fiber contents of UHPC (0%, 1%, and 2%) on their flexural performance. Four-point bending tests are conducted to obtain the failure modes, load-deflection characteristics, and strain responses of each testing beam, and a simplified calculation method for cracking loading and flexural bearing capacity is proposed. The results reveal that the increase in FRP grid thickness, the ultimate load bearing capacity of FRP grid-reinforced UHPC structural beams increases and the ductility also can be enhanced. The presence of steel fiber effectively inhibits the cracking and increases the first cracking load of the beam during the test process, although its influence on the ultimate bearing capacity is limited. Besides, until to the cracking stage, there is no noticeable change in the tensile strain of the FRP grids as the applied load increases. It has been used to simplify theoretical calculations, which shows good agreement with the experimental results.

Observing perineuronal nets like structures via coaxial scattering quantitative interference imaging at multiple wavelengths

Perineuronal nets (PNNs) are important functional structures on the surface of nerve cells. Observation of PNNs usually requires dyeing or fluorescent labeling. As a network structure with a micron grid and sub-wavelength thickness but no special optical properties, quantitative phase imaging (QPI) is the only purely optical method for high-resolution imaging of PNNs. We proposed a Scattering Quantitative Interference Imaging (SQII) method which measures the geometric rather than transmission or reflection phase during the scattering process to visualize PNNs. Different from QIP methods, SQII method is sensitive to scattering and not affected by wavelength changes. Via geometric phase shifting method, we simplify the phase shift operation. The SQII method not only focuses on interference phase, but also on the interference contrast. The singularity points and phase lines of the scattering geometric phase depict the edges of the network structure and can be found at the valley area of the interference contrast parameter SIND R under different wavelengths. Our SQII method has its unique imaging properties, is very simple and easy to implement and has more worth for promotion.

Research on the Equivalent Circuit Model of Electromagnetic Shielding and the Critical Thickness of the Metal Grid

Research on the Equivalent Circuit Model of Electromagnetic Shielding and the Critical Thickness of the Metal Grid

Thickness, Adhesion and Microscopic Analysis of the Surface Structure of Single-Layer and Multi-Layer Metakaolin-Based Geopolymer Coatings

This work is focused on creating coating layers made of a metakaolin-based geopolymer suspensions (GP)-formed Al matrix modified using H3PO4 acid with Al(OH)3 in isopropyl alcohol, named GP suspension I, and H3PO4 acid with nano Al2O3 in isopropyl alcohol, named GP suspension J. The selected GP suspensions were applied on aluminum and steel underlying substrates as single-layer coatings and multi-layer coatings, where multi-layer coatings included three and five layers that were polymerized by a curing process. Curing was divided into two types with every layer curing process and final layer curing process. For both GP suspensions I and J, the effect of the number of layers and the type of substrate on adhesion was investigated. The prepared samples on underlying substrates were characterized on the microscopy analysis including SEM for high-resolution images and 3D laser confocal microscopy (CLSM) for the 3D visualization of the coatings structure. Microscopy analysis showed structural defects such as porosity, cracks and peeling, which increase with a greater number of applied layers. However, these defects were only evident on a micro scale and did not seem to be fatal for the performance of the surface stability. The EDS mapping of the prepared layer showed inhomogeneity in the distribution of elements caused by the brush application. A grid test and thickness measurement were performed to complete the microscopy analysis. The grid test confirmed a very high adhesion of GP coatings on the aluminum substrate with a rating of one (only in one case was there a rating of two) and a lower adhesion on the steel substrate with the most frequent rating of three (in one case, there were ratings of two and one). The thickness measurement proved a noticeably thicker thickness of the prepared layer on the Fe substrate compared to the Al substrate by 20%–30% in the case of suspension I and by 70%–10% in the case of suspension J. The thickness of the layer also showed a dependence on the method of application and curing, as a thicker layer was always achieved when curing after the final layer of the GP suspension, compared to curing after each applied layer. The resulting single-layer and multi-layer thicknesses ranged from approx. 7 to 30 µm for suspension I and from approx. 3 to 11 µm for suspension J. A non-linear increase in thickness was also evident from the thickness measurement data.

Study on the effect of near-wall grid on numerical prediction of resistance for planing trimaran

A near-wall grid is a critical factor affecting the accuracy of numerical predictions for planing trimarans (double tunnel-planing boats). This study utilizes STARCCM + to investigate the influence of dimensionless near-wall first-layer grid thickness (y1+) on the numerical simulation of the resistance of planing trimarans. By comparing the computational fluid dynamics results with experimental values, the variation in y1+ is found to have a significant impact on the numerical simulation of the resistance of planing trimarans; as the sailing speed increases, the optimal y1+ value decreases. In this study, the changes in the flow field of a planing trimaran are analyzed. The air flow obstruction caused by the front part of the tunnel is observed to intensify with increasing y1+. Consequently, the pressure resistance between the front and rear of the tunnel increases. Furthermore, the increase in y1+ hinders the flow separation at the step, leading to an increase in the wetted area of the step's aft portion; consequently, the resistance calculated in the simulation increases. This study provides a reference for the selection of y1+ for planing trimarans, thereby reducing the time apportioned to mesh independence testing.

The Lark: reducing carbon emissions through collaboration and good relationships – a model for everyday concrete frames

Multistorey concrete-framed residential buildings are a common choice for developers because of their strength, durability, inherent fire resistance, design flexibility, and cost-effectiveness. However, with concrete accounting for a significant portion of global carbon emissions, engineers have a responsibility to both minimise concrete volumes and reduce the carbon intensity of concrete mixes to deliver a sustainable solution. In this article, Peyrouz Modarres of Walsh describes the consultant's approach to the engineering design of The Lark, a multistorey residential project at Nine Elms, London. The article examines the optioneering process through which the grid and slab thicknesses were optimised to reduce the embodied carbon of the sub- and superstructure, collaboration with the contractor over the concrete specification, and the benefits that a trusted relationship with the client brought to the project.

Low-velocity impact response of composite sandwich structure with grid–honeycomb hybrid core

Grid structures have great potential for engineering application, inspired by the leaf texture, the rectangular grid is innovatively added to the honeycomb to form the grid-honeycomb hybrid core. The low-velocity impact response of the composite sandwich structure with grid–honeycomb hybrid core was investigated by experimental and numerical simulation. Low-velocity impact tests with 30 J energy were conducted of the sandwich panel to analyze the mechanical response and damage morphology at typical locations (intersection, rib, and center). The results show that the impact resistance at the intersection was the strongest, the peak load, damage threshold load, and initial stiffness at the intersection were 14.74%, 15.54%, and 16.06% higher, and the maximum displacement and residual displacement were 12.09% and 33.71% lower, respectively than those at the rib, and the center was the weakest. Compared with honeycomb sandwich panel, the impact resistance of unit mass at the intersection and rib was stronger and the internal damage was smaller. In addition, the parametric study of the structural parameters of sandwich panel was conducted. The grid thickness had a significant effect on the impact resistance, while the effects of honeycomb wall thickness and honeycomb unit cell diameter were smaller and had almost no effect on initial stiffness and energy absorption. Finally, the impact resistance efficiency analysis was performed to obtain the optimal design area of structural parameters to provide design guidance.

Winter Arctic sea ice thickness from ICESat-2: upgrades to freeboard and snow loading estimates and an assessment of the first three winters of data collection

Abstract. NASA's ICESat-2 mission has provided near-continuous, high-resolution estimates of sea ice freeboard across both hemispheres since data collection started in October 2018. This study provides an impact assessment of upgrades to both the ICESat-2 freeboard data (ATL10) and NASA Eulerian Snow On Sea Ice Model (NESOSIM) snow loading on estimates of winter Arctic sea ice thickness. Misclassified leads were removed from the freeboard algorithm in the third release (rel003) of ATL10, which generally results in an increase in freeboards compared to rel002 data. The thickness increases due to increased freeboards in ATL10 improved comparisons of Inner Arctic Ocean sea ice thickness with thickness estimates from ESA's CryoSat-2. The upgrade from NESOSIM v1.0 to v1.1 results in only small changes in snow depth and density which have a less significant impact on thickness compared to the rel002 to rel003 ATL10 freeboard changes. The updated monthly gridded thickness data are validated against ice draft measurements obtained by upward-looking sonar moorings deployed in the Beaufort Sea, showing strong agreement (r2 of 0.87, differences of 11 ± 20 cm). The seasonal cycle in winter monthly mean Arctic sea ice thickness shows good agreement with various CryoSat-2 products (and a merged ICESat-2–CryoSat-2 product) and PIOMAS (Pan-Arctic Ice-Ocean Modeling and Assimilation System). Finally, changes in Arctic sea ice conditions over the past three winter seasons of data collection (November 2018–April 2021) are presented and discussed, including a 50 cm decline in multiyear ice thickness and negligible interannual differences in first-year ice. Interannual changes in snow depth provide a notable impact on the thickness retrievals on regional and seasonal scales. Our monthly gridded thickness analysis is provided online in a Jupyter Book format to increase transparency and user engagement with our ICESat-2 winter Arctic sea ice thickness data.

Диагностическое значение макулярного кровотока при глаукоме низкого давления

Aim: to evaluate macular microcirculation in patients with early newly diagnosed normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG) with elevated IOP using optical coherence tomography angiography (OCTA). Patients and Methods: patients aged 45–65 years with early newly diagnosed NTG (35 patients, 35 eyes) or POAG with elevated IOP (43 patients, 43 eyes) and healthy individuals without ocular disorders (n=50) were examined. All patients underwent OCTA by measuring vascular density (VD, %) using the ETDRS grid (central Fovea and Parafovea) and retinal thick-ness using the Angio Retina 3.0 protocol of the Optovue XR Avanti with the AngioVue function (Optovue, USA). Results: in patients with NTG and POAG, a decrease in vascular density in the superficial choroid plexus was detected. In patients with NTG, retinal thickness in the Fovea, Parafovea, Inferior, and Nasal quadrants was lower than that in the control group and correlated with VD in the Fovea and superior Parafovea of the superficial choroid plexus. The severity of focal losses of the retinal ganglion cell complex was lower than that in the control group and demonstrated a significant weak negative correlation (r=-0.487, p<0.01) with the vascular density index in the Fovea of the superficial choroid plexus. In patients with POAG, retinal thickness in the Fovea and Parafovea was also reduced and correlated with vascular density in the temporal and inferior Parafovea. The severity of global losses of the retinal ganglion cell complex demonstrated a weak negative correlation (r=-0.464, p<0.01) with microcirculation density in the Fovea of the superficial retinal choroid plexus. Conclusion: OCTA revealed a decrease in vascular density in the superficial choroid plexus in early glaucoma. Moreover, a significant difference between NTG and POAG in the Fovea and Parafovea was revealed. Our study established the predominance of vascular changes in patients with NTG. OCTA parameters of the superficial choroid plexus identify microcircula-tion abnormalities at early glaucomatous damage. KEYWORDS: primary open-angle glaucoma, normal tension glaucoma, OCT, optical coher-ence tomography angiography, vascular density index. FOR CITATION: Zagidullina A.Sh., Galimova V.U., Arslanova A.I., Nugmanova A.R. Diagnostic value of macular blood flow in normal tension glaucoma. Russian Journal of Clinical Ophthalmology. 2023;23(4):174–180 (in Russ.). DOI: 10.32364/2311-7729-2023-23-4-1.

RhBMP-2-Conjugated Three-Dimensional-Printed Poly(L-lactide) Scaffold is an Effective Bone Substitute.

Bone growth factors, particularly bone morphogenic protein-2 (BMP-2), are required for effective treatment of significant bone loss. Despite the extensive development of bone substitutes, much remains to be desired for wider application in clinical settings. The currently available bone substitutes cannot sustain prolonged BMP-2 release and are inconvenient to use. In this study, we developed a ready-to-use bone substitute by sequential conjugation of BMP to a three-dimensional (3D) poly(L-lactide) (PLLA) scaffoldusing novel molecular adhesive materials that reduced the operation time and sustained prolonged BMP release. A 3D PLLA scaffold was printed and BMP-2 was conjugated with alginate-catechol and collagen. PLLA scaffolds were conjugated with different concentrations of BMP-2 and evaluated for bone regeneration in vitro and in vivo using a mouse calvarial model. The BMP-2 release kinetics were analyzed using ELISA. Histological analysis and micro-CT image analysis were performed to evaluate new bone formation. The 3D structure of the PLLA scaffold had a pore size of 400µm and grid thickness of 187-230µm. BMP-2 was released in an initial burst, followed by a sustained release for 14days. Released BMP-2 maintained osteoinductivity in vitro and in vivo. Micro-computed tomography and histological findings demonstrate that the PLLA scaffold conjugated with 2µg/ml of BMP-2 induced optimal bone regeneration. The 3D-printed PLLA scaffold conjugated with BMP-2 enhanced bone regeneration, demonstrating its potential as a novel bone substitute.

Flexural behavior of pre-damaged and repaired reinforced concrete beams with carbon fiber reinforced polymer grid and engineered cementitious composite

In this study, the flexural behavior of pre-damaged reinforced concrete (RC) beams repaired with carbon fiber reinforced polymer (CFRP) grids and engineered cementitious composite (ECC) was investigated. Fifteen beams were designed and subjected to four-point bending tests. Three types of specimens were tested: undamaged, pre-damaged with removed load (i.e., loaded to the target level and then unloaded), and pre-damaged under sustained load. The main testing parameters were strengthening material (ECC alone, or CFRP grid plus ECC), CFRP grid thickness, main reinforcement ratio, preloaded level, and repairing process. The experimental results showed that most of the repaired beams exhibited flexural failure caused by concrete crushing, and a few others failed by debonding. The proposed repairing technique was effective in enhancing the flexural stiffness and bearing capacity of pre-damaged RC beams. For the repaired beams, the flexural bearing capacities did not significantly decrease as the preloaded level increased from 0 to 0.45 and slightly decreased when the preloaded level exceeded 0.65. A mathematical model based on the plane section assumption was proposed to predict the flexural capacities of the repaired beams, considering whether the load causing the damage was removed or sustained. The predicted capacities were in good agreement with the experimental results.

Satellite Altimetry and Gravimetry Data for Mapping Marine Geodetic and Geophysical Setting of the Seychelles and the Somali Sea, Indian Ocean

AbstractEvaluation of the representative cartographic techniques demonstrated that there are still considerable challenges facing the methods of marine geodetic, geophysical and bathymetric data visualisation. In an oceanic seafloor formation, the interaction between the geological structural elements and topographical relief can be analysed by advanced mapping. In present study, a correlation between geodesy, geophysics and topography has been examined including the following variables: geological structure, coastal topography and bathymetry, geophysical fields, free-air gravity anomalies and geoid undulation, sediment thickness, bathymetric patterns, and extension of the transform faults. The variables were visualised on the high-resolution raster grids using Generic Mapping Tools (GMT) scripting toolset. The study area is located in the Seychelles and the Somali Sea segment of the Indian Ocean. The data incorporates satellite-derived gravity grid, EGM-2008, geological structures, topography from GEBCO grid and GlobSed sediment thickness, processed by GMT scripts. The results demonstrated that western continental slope of Somalia is wide, gently declining to the seafloor at depths exceeding -5000 m. Kenya and Tanzania present a wide continental foot with depths ranging from -3500 to -5000 m. The Somali Sea basin shows low sedimentation lower than 500 m, while ridges and island chains have higher sediment influx (1,000-2,000 m). The Mozambique Channel has dominating values at 2,500-3,500 m. Higher values are noted near the Reunion and Mauritius islands until the Seychelles via the Mascarene Plateau (500-1,000 m) against the <500 m in the areas of the Mid-Indian Ridge, Carlsberg Ridge and open water.

Bond Stress-Slip Model of BFRP Grid to ECC.

The bonding performance between a basalt fiber-reinforced composite material (BFRP) grid and an engineering cementitious composite (ECC) is the basis that affects the synergy between the two. However, the research on the bonding behavior between the FRP grid and ECC is limited; in particular, the theoretical study on the bond-slip intrinsic relationship model and a reliable anchorage length calculation equation is lacking. To study the bond-slip relationship between the BFRP grid and ECC material, we considered the parameters of BFRP grid thickness, anchorage length, ECC substrate protective layer thickness, and grid surface treatment, and conducted center pull-out tests on eight sets of specimens. By analyzing the characteristics of the bond-slip curve of the specimen, a bond-slip constitutive model between the BFRP grid and ECC was established. Combining the principle of equivalent strain energy, the calculation formula of the basic anchorage length of the BFRP grid in the ECC matrix was derived. Research shows that the bonding performance between the BFRP grid and ECC improves with the increase in the grid anchoring length, grid thickness, and ECC layer strength. Sand sticking on the surface of the BFRP grid can enhance the bonding force between the two. The established bond-slip constitutive model curve is in good agreement with the test curve. The bond-slip relationship between the BFRP grid and ECC can be described by the first two stages in the BPE model. The derived formula for calculating the basic anchorage length of the BFRP mesh in the ECC matrix is computationally verified to be reliable in prediction.

INVESTIGATION OF THE PERFORMANCE OF RC BEAMS REINFORCED WITH FRP AND ECC MATERIALS

This paper investigates the structural working behavior of reinforced concrete beams bonded with fiber reinforced polymer and engineered cementitious composite materials subjected to bending using structural stressing state theory. First, six reinforced concrete beams externally bonded with composite reinforcement layer and one control beam are tested to investigate the effects of the bond length, fiber reinforced polymer grid thickness and fiber content on the flexural behavior. Then, the finite strain data of RC beams are interpolated by the numerical shape function method. The generalized strain energy density model is established to characterize the stressing state of the structure. Through the MannKendall criterion, the characteristics load P and Q of the beams are detected, and the whole loading process is divided into three stage. Finally, the analysis of the strain and deformation on the beams reveals the effect of different parameters on different stage. The characteristic load P increases as the bond length increases, and the characteristic load Q increases as the thickness of the FRP and the fiber content increase. The vertical deformation of the strengthened beam for the characteristic load Q and ultimate load is significantly smaller than that of the unreinforced beam.

Fabrication and performances of silver grid transparent conducting films and heaters on glass and PET substrates based on fractal periodic grid pattern design

A metal grid transparent conducting film (TCF) requires an excellent trade-off between optical transparency and electrical conductivity, both of which are affected by grid patterns and parameters. In this work, the fractal geometry was introduced to design fractal periodic grid patterns, which were employed to fabricate fractal periodic Ag grid TCFs with different grid periods, pitches and thicknesses on glass substrates by magnetron sputtering Ag films and laser localized removal. By comparing with the corresponding conventional periodic Ag grid, the fractal periodic Ag grid was confirmed to enable a significant improvement in trade-off between optical transparency and electrical conductivity, and thus excellently improving the comprehensive properties of the TCFs. The optimal fractal periodic Ag grid TCF achieved a figure of merit of 15.04 × 10–2 Ω–1, which was higher than that of the optimal conventional periodic Ag grid TCF (11.38 × 10–2 Ω–1). In addition, transparent heaters were prepared by using the optimal fractal periodic Ag grid TCFs on glass and flexible PET substrates, and showed excellent heating performances, good performance stability and deicing availability. This work provides a simple and extendable method for tailoring optical transmittance and electrical conductivity to fabricate high-performance TCFs.

High-Density Optical Coherence Tomography Analysis Provides Insights Into Early/Intermediate Age-Related Macular Degeneration Retinal Layer Changes.

PurposeTo topographically map all of the thickness differences in individual retinal layers between early/intermediate age-related macular degeneration (AMDearly/AMDint) and normal eyes and to determine interlayer relationships.MethodsNinety-six AMDtotal (48 AMDearly and 48 AMDint) and 96 normal eyes from 192 participants were propensity-score matched by age, sex, and refraction. Retrospective optical coherence tomography (OCT) macular cube scans were acquired, and high-density (60 × 60 0.01-mm2) grid thicknesses were custom extracted for comparison between AMDtotal and normal eyes corrected for confounding. Resultant “normal differences” underwent cluster, interlayer correlation, and dose–response analyses for the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer + Henle's fiber layer (ONL+HFL), inner and outer segment (IS/OS) thickness, and retinal pigment epithelium (RPE) to Bruch's membrane (BM) thickness.ResultsAMDtotal inner retinal clusters demonstrated extensively thinned RNFL, GCL, IPL, and paracentral INL and thickened INL elsewhere, with normal difference means ranging from −8.13 µm (95% confidence interval [CI], −11.12 to −5.13) to 1.58 µm (95% CI, 1.07–2.09) (P < 0.0001 to P < 0.05). Outer retinal clusters displayed thinned paracentral OPL/ONL+HFL, central IS/OS, and peripheral RPE–BM and thickened central RPE–BM, with means ranging from −1.31 µm (95% CI, −2.06 to −0.55) to 2.99 µm (95% CI, 0.97–5.01] (P < 0.0001 to P <0.05). Effect sizes (−2.56 to 9.93 SD), cluster sizes, and eccentricity effects varied. All interlayer correlations were negligible to moderate regardless of AMD severity. Only the RPE–BM was partly thicker with greater AMD severity (up to 5.44 µm; 95% CI, 4.88–6.00; P < 0.01).ConclusionsFrom the early stage, AMD eyes demonstrate thickness differences compared to normal with unique topographies across all retinal layers. Poor interlayer correlations highlight that the outer retina inadequately reflects complete retinal health. The clinical importance of OCT assessment across all individual retinal layers in early/intermediate AMD requires further investigation.

Rapid Objective Testing of Visual FunctionMatched to the ETDRS Grid and ItsDiagnostic Power in Age-Related MacularDegeneration.

PurposeTo study the power of an 80-second multifocal pupillographic objective perimetry (mfPOP) test tailored to the ETDRS grid to diagnose age-related macular degeneration (AMD) by Age-Related Eye Disease Study (AREDS) severity grade.DesignEvaluation of a diagnostic technology.MethodsWe compared diagnostic power of acuity, ETDRS grid retinal thickness data, new 80-second M18 mfPOP test, and two wider-field 6-minute mfPOP tests (Macular-P131, Widefield-P129). The M18 stimuli match the size and shape of bifurcated ETDRS grid regions, allowing easy structure–function comparisons. M18, P129, and P131 stimuli test both eyes concurrently. We recruited 34 patients with early-stage AMD with a mean ± standard deviation (SD) age of 72.6 ± 7.06 years. The M18 and P129 plus P131 stimuli had 26 and 51 control participants, respectively with mean ± SD ages of 73.1 ± 8.17 years and 72.1 ± 5.83 years, respectively. Multifocal pupillographic objective perimetry testing used the Food and Drug Administration-cleared Objective FIELD Analyzer (OFA; Konan Medical USA).Main Outcome MeasuresPercentage area under the receiver operator characteristic curve (AUC) and Hedge’s g effect size.ResultsAcuity and OCT ETDRS grid thickness and volume produced reasonable diagnostic power (percentage AUC) for AREDS grade 4 eyes at 83.9 ± 9.98% and 90.2 ± 6.32% (mean ± standard error), respectively, but not for eyes with less severe disease. By contrast, M18 stimuli produced percentage AUCs from 72.8 ± 6.65% (AREDS grade 2) to 92.9 ± 3.93% (AREDS grade 4), and 82.9 ± 3.71% for all eyes. Hedge’s g effect sizes ranged from 0.84 to 2.32 (large to huge). Percentage AUC for P131 stimuli performed similarly and for P129 performed somewhat less well.ConclusionsThe rapid and objective M18 test provided diagnostic power comparable with that of wider-field 6-minute mfPOP tests. Unlike acuity or OCT ETDRS grid data, OFA tests produced reasonable diagnostic power in AREDS grade 1 to 3 eyes.

Finite Element Simulation of Electrical Intradevice Physics of Thin-Film Solar Cells and Its Implications on the Efficiency

One key aspect to further improve thin-film photovoltaic devices is the optimal sizing of the different layers, such as grids, transparent conducting oxides (TCOs), back contacts, and absorber materials, with respect to their mutual electrical influences. This article describes a novel quasi-3-D finite element method (FEM) tool on a digital twin, which is capable of simulating all electrical influences from a holistic perspective from semiconductor materials to device level. It yields a spatially resolved intradevice distribution of electrical potentials and currents, helping to understand the physical processes within solar cell devices. Experimentally inaccessible data, such as the breakdown of different loss mechanisms, can be provided. Moreover, the internal cell properties can be used for forecasting calculations of characteristic <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–V</i> curves. This process can also be reversed in a procedure called reverse engineering fitting. It allows to calculate backward from the external cell properties to the internal loss-exempt semiconductor material characteristics. Our approach is verified by semitransparent cells with a perovskite absorber, a silver rear metalization grid, and indium zinc oxide as a rear TCO. Our simulation predicts characteristic <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–V</i> curves with a coefficient of determination of well above 0.99 with respect to experimentally measured cells. The power conversion efficiency (PCE) can be forecast within a mean error of 0.18% <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{\mathrm{abs}}$</tex-math></inline-formula> at absolute PCEs around 13% for different TCO and grid thicknesses. The advantage of our FEM approach in contrast to a single-diode equivalent circuit model is demonstrated by considering <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–V</i> curve predictions for different cell sizes.

High-performance transparent conductive film by using ultra-thin metal grids

Transparent conductive films (TCFs) are indispensable for many optoelectronic devices. Films with high transmittance and low sheet resistance at low cost are ideal for people to pursue. In this paper, ultra-thin Au grid TCFs with thickness less than 0.32 μm are developed and fabricated by ultraviolet lithography. Nanoscale thick metal grid and simple experimental steps can greatly reduce their cost. The influence of grid shape (square, hexagon, ring), thickness and duty ratio on the transmittance and sheet resistance has been investigated systematically. The TCF with square shape Au grid has excellent properties with transmittance of 96.9%, sheet resistance of 11.5 Ω sq−1, and corresponding figure of merit of 1016. It is a good transparent heater with heating speed 100% faster and heating temperature 3.3% higher than indium tin oxide. It can also be fabricated on flexible substrates and exhibit good mechanical property, which have wide practical applications.