Large Geometry Research Articles

Behavior of Reinforced Gypseous Soil Embankment Model under Cyclic Loading

The construction of embankment for roadway interchange system at urban area is restricted due to the large geometry requirements, since the value of land required for such construction is high, and the area available is limited as compared to rural area. One of the optimum solutions to such problem is the earth reinforcement technique which requires a limited area for embankment construction. Gypseous soil from Al-Anbar governorate area was obtained and subjected to various physical and chemical analysis to determine it is properties. A laboratory model box of 50x50x25 cm was used as a representative embankment; soil has been compacted in five layers at maximum dry density (modified compaction) and an aluminum reinforcement strips were introduced between layers. The model was subjected to cyclic loading and the vertical and lateral deformations were detected at different stages of loading cycles using LVDT. The reinforced soil embankment under soaking condition exhibited vertical settlement at the top surface was (12.55 mm) while the lateral displacements at (1st, 3rd layer) were (2.18, 1.32) mm respectively at (47 load cycles).For reinforced gypseous soil, embankment without soaking cured for 24 hours, the Number of load cycles was found to be (165) loading cycles with vertical displacement (9.12 mm), that means an improvement of 59%. Accordingly, the lateral displacement in 1st and 3rd layers were (3.28, 2.59) mm respectively which observes improvement by (28% and 5%) respectively. The rates of improvement are taken with respect to the reinforced pure dry soil sample.

A Mechanized Air-Atomized Spray Coating Method for Fabricating Flexible Nanocomposite Piezoresistive Strain Sensors

Nanocomposite piezoresistive strain sensors have offered new avenues for strain measurement of structures with significant deformations, large geometries or complex contours. The affordable and efficient spray coating technique, especially the air-atomized spray coating method, has considerable potential for batch production of such sensors. However, one of the most popular ways to fabricate sensors is manual spray coating, which not only has a low transfer efficiency, resulting in material waste and environmental pollution, but also makes it challenging to precisely control the homogeneity of sensor coatings, leading to inconsistent quality of existing sprayed sensors. Therefore, a mechanized air-atomized spray coating method is proposed to actualize the stable batch production of sprayed sensors, and spraying parameters are then determined to establish proper process conditions. Carbon black (CB) nanoparticle reinforced polyvinyl pyrrolidone (PVP) nanocomposites are prepared to fabricate CB/PVP strain sensors to validate the proposed method. Compared with the manual spray coating, the proposed method can manufacture CB/PVP coatings with uniform thickness distribution and micro-morphology. Additionally, the mechanical and electrical properties of CB/PVP nanocomposites are subsequently investigated to verify the consistency of coating quality using nanoindentation and four-probe techniques, respectively. Furthermore, the superior sensitivity and large strain range of CB/PVP strain sensors are evaluated by uniaxial tensile testing. In conclusion, the mechanized air-atomized spray coating method is not only time-saving, inexpensive and straightforward to implement, but also features wide applicability due to minor requirements for nanocomposites, thus laying a foundation for batch production and popularization of nanocomposite piezoresistive strain sensors.

PFH spectral invariants on the two-sphere and the large scale geometry of Hofer’s metric

We resolve three longstanding questions related to the large scale geometry of the group of Hamiltonian diffeomorphisms of the two-sphere, equipped with Hofer’s metric. Namely: (1) we resolve the Kapovich–Polterovich question by showing that this group is not quasi-isometric to the real line; (2) more generally, we show that the kernel of Calabi over any proper open subset is unbounded; and (3) we show that the group of area and orientation preserving homeomorphisms of the two-sphere is not a simple group. We also find, as a corollary, that the group of area-preserving diffeomorphisms of the open disc, equipped with an area form of finite area, is not perfect. Central to all of our proofs are new sequences of spectral invariants over the two-sphere, defined via periodic Floer homology.

Detection and Characterization of Artificial Porosity and Impact Damage in Aerospace Carbon Fiber Composites by Pulsed and Line Scan Thermography

Nondestructive testing (NDT) of composite materials is of paramount importance to the aerospace industry. Several NDT methods have been adopted for the inspection of components during production and all through the aircraft service life, with infrared thermography (IRT) techniques, such as line scan thermography (LST) and pulsed thermography (PT), gaining popularity thanks to their rapidity and versatility. On one hand, LST is an attractive solution for the fast inspection of large and complex geometry composite parts during production. On the other hand, PT can be employed for the characterization of composite materials, e.g., the determination of thermal diffusivity and defect depth estimation. In this study, the use of LST with an uncooled microbolometer camera is explored for the identification of artificially produced porosity and barely visible impact damage (BVID) on academic samples. The performance of LST is quantitatively assessed with respect to PT (considered the gold standard in this case) using a high-definition cooled camera through the contrast-to-noise ratio (CNR) criterium. It is concluded that, although in most cases the measured CNR values were higher for PT than for LST (as expected since a high-definition camera and longer acquisition times were used), the majority of the defects were clearly detected (CNR ≥ 2.5) by LST without the need of advanced signal processing, proving the suitability of LST for the inspection of aerospace composite components. Furthermore, the deepest defect investigated herein (z ≈ 3 mm) was detected solely by LST combined with signal processing and spatial filtering (CNR = 3.6) and not by PT (since pulse heating was not long enough for this depth). In addition, PT was used for the determination of the thermal diffusivity of all samples and the subsequent depth estimation of porosity and damaged areas by pulsed phase thermography (PPT).

Geometry-influenced cooling performance of lithium-ion battery

Battery geometry (shape and size) is one of the important parameters which governs the battery capacity and thermal behavior. In the dynamic conditions or during the operation, the performance of batteries become much more complex. Herein, the changes in thermal behavior of lithium-ion battery (LIB)by altering the geometry i.e., length to diameter ratio (l/d), is investigated. The geometries considered are named as large geometry (LG), datum geometry (DG) and small geometry (SG) with the l/d ratio of 5.25, 3.61, and 2.38, respectively. A three-dimensional (3D) multi-partition thermal model is adopted, and the numerical results are validated by the published experimental data. For three different cooling approaches such as radial, both-tab and mixed cooling, the average battery temperature and temperature heterogeneity are thoroughly examined considering the heat transfer coefficients (h) of 50 and 100 W/m2K at discharge rates of 1, 2 and 3C. Amongst, the minimum average battery temperature is exhibited by DG, the minimum radial temperature heterogeneity is obtained from LG, and substantial outperformance in terms of faster cooling rate is identified for SG, irrespective of the cooling approach employed.

Large underground structures geometry evaluation based on point cloud data analysis

As a result of underground exploitation performed by blasting technique or mechanical excavation large underground structures are created. Usually, due to the mining and geological conditions of the exploitation, obtained excavations geometry may be far from this assumed at the design stage. The geometry of the excavations is of key importance in several important stages of the technological process. Taking into account economic issues, deviations from the planned cross-section of the excavation generate additional, often considerable operating costs. If the cross-sectional area is greater than the assumed one, the ore may be impoverished, since the dimensions of mining faces are usually following the dimensions of the deposit zone. On the other hand, when the cross-sectional area is smaller than assumed, to maintain the proper operation of the mining plant, it is necessary to re-cut the excavation. It is particularly important from a mine ventilation point of view, as it generates problems in supplying adequate amounts of air to work areas, as well as transport, causing a significant problem for moving machines. Underground mine workings tend to change over time as a result of processes taking place in the rock mass aimed at establishing a new stress and strain state of rock mass after the excavation has been made. Considering the extent of underground mining structures, there is a need to develop a method that would allow the assessment of the geometry of workings, both newly created and existing ones, with the assumption of quick acquisition of measurement data, their processing, and analysis. Addressing those needs, in this paper, the authors are presenting a method based on a 3D point cloud of excavation geometry obtained thanks to measurements with the use of Terrestrial Laser Scanner/LiDAR, the procedure used to convert the point cloud into a spatial model of excavations, as well as data processing procedures used to extract informative parameters describing the geometry. Several statistical parameters are proposed for feature analysis along the tunnel length.

High-resolution lightweight and multifunctional 3D printed scaffolds for cell studies

Additive manufacturing is gaining popularity for its limitless possibilities in fields requiring 3D structure fabrication, including tissue engineering. While established methods like Multi-Photon Polymerization and Selective Laser Melting offer high-resolution structures, they exhibit common drawbacks such as high cost, large equipment size and long fabrication times. On the other hand, 3D printers that utilize UV Polymerization are becoming more affordable, allowing for printing 3D scaffolds that could be used as transplantable grafts for tissue regeneration and other biomedical applications. In this study, we used a Light-Emitting-Diode-based 3D printer with a pixel size of 35 μm alongside two commercially available resins to fabricate a variety of high-resolution, large scaffold geometries. Resin and scaffold suitability was examined using 4 common cell lines and various techniques such as MTT cell viability assays, confocal microscopy and Scanning Electron Microscopy. The results highlight the possibility to successfully use widely-available, low-cost 3D printers for high-resolution scaffold fabrication while maintaining cell culture compatibility for biomedical applications.

Channel Selectivity of Satellite Transponders with the Antenna Combined with a Size-Reduced Metallic Waveguide Bandpass Filter Having Thin Metamaterial Resonators.

Global and intercontinental networking relies on satellite communication. Its wireless communication system always has antennas and their feed assembly comprising waveguides. This makes the satellite payload heavy and costly. In this paper, a novel method is proposed to effectively reduce the size of a waveguide bandpass filter (BPF). Because the metallic cavities make the conventional waveguide end up with a large geometry, especially for high-order BPFs, very compact waveguide-type resonators having metamaterial zeroth-order resonance (WG-ZOR) are designed on the cross-section of the waveguide and substituted for the cavities. While the cavities are half-wavelength resonators, the WG-ZOR is shorter than one eighth of a wavelength. A substantial reduction in size and weight of the waveguide filter is observed as the resonators are cascaded in series through coupling elements in the X-band much longer than K- or Ka-band. An X-band of 7.25~7.75 GHz is chosen to verify the method as the passband with attenuation of 40 dB at 7.00 GHz and 8.00 GHz as the roll-off in the stopband. The BPF is manufactured using the CNC milling technique. The design is carried out with geometrical parameters, not of the level of 10 μm, but the level of 100 μm, which is good for manufacturers but a big challenge for component designers. The measurement of the manufactured metal waveguide filter reveals that the passband has about ≤1 dB and ≤-15 dB as insertion loss and reflection coefficient and the stopband has ≤-40 dB as attenuation, which are in good agreement with the results of the circuit and simulation. The proposed filter has a length of 3.5 λg as the eighth-order BPF, but the conventional waveguide is 5 λg as the seventh-order BPF for the same area of the cross-section. This metamaterial BPF is combined with a horn antenna. The filter enables the wide-band antenna to distinguish the band of transmission from that of noise suppression. This channel selectivity is obviously observed by the filter integrated antenna test.

Monte Carlo burnup oscillations for thorium-based EPR fuel

Advanced codes and computational resources have made it possible to model large geometries with finer spatial discretisation, which are required for detailed fuel analysis and licencing. Unfortunately, these detailed models exhibit instabilities during Monte Carlo burnup calculations. Several solutions for stabilising the combined transport and depletion calculations have been developed. This study focusses on the burnup instabilities that arise specifically for thorium-based fuels and employed existing methods to test the robustness and accuracy. The methods are evaluated in terms of burnup, isotopic masses and flux plots. The results proved that various methods can be employed to stabilise the oscillations, specifically for the proposed modification of the EPR using thorium. In particular, using the stochastic implicit Euler method and reducing the time step length (maximum 11.3 days) produced stable results. Thorium-based fuel appears to be particularly sensitive to the evolution of time step length as well as Pa233 concentration.

Effective Size Reduction of the Metallic Waveguide Bandpass Filter with Metamaterial Resonators and Its 3D-Printed Version.

In this paper, a novel method is proposed to effectively reduce the size of a waveguide bandpass filter (BPF). Because the metallic cavities make the conventional waveguide end up with a large geometry, especially for high-order BPFs, very compact waveguide-type resonators having metamaterial zeroth-order resonance (WG ZOR) are designed on the cross section of the waveguide and substituted for the cavities. While the cavities are half-wavelength resonators, the WG ZOR is shorter than one-eighth of a wavelength. A substantial reduction in the size and weight of the waveguide filter is observed as the resonators are cascaded in series through coupling elements in the X-band that is much longer than that in K- or Ka-bands. The proposed metamaterial filter is realized as a 3D-printed structure to be lighter and thus more suitable for low earth orbit (LEO) satellites. An X-band of 7.25-7.75 GHz is chosen to verify the method as the passband with an attenuation of 40 dB at 7.00 GHz and 8.00 GHz as the roll-off in the stopband. The BPF is manufactured in two ways, namely the CNC-milling technique and metal coating-added 3D printing. The design is carried out with a geometrical parameter of not 10-2 mm but rather 10-1 mm, which is good for manufacturers but challenging for component designers. The measurement of the manufactured metal waveguide filters reveals that the passband has about ≤1 dB and ≤-15 dB as the insertion loss and the reflection coefficient, respectively, and the stopband has an attenuation of ≤-40 dB, which are in good agreement with the results of the circuit and the simulation. The proposed filter has a length of 14 cm as the eighth-order BPF, but the conventional waveguide is 20 cm as the seventh-order BPF for the same area of the cross section.

Evaluation and comparison of VIIRS dark target and deep blue aerosol products over land

The dark target (DT) and deep blue (DB) algorithms have been applied to the VIIRS to construct a long-term climate data recording of atmospheric aerosols. This study provides the first evaluation and comparison of two updated VIIRS aerosol products over global land based on Version 3 Level 1.5 AERONET measurements. Overall, both AOD products agree well with AERONET measurements with correlation coefficients >0.85 and over 75 % of AOD matchups falling within the expected error (EE). The DB product is superior to the DT product with more AOD matchups meeting the EE. Meanwhile, the DB AOD performs better in spatiotemporal accuracy, adaption to different aerosol types, and addresses the effects of large view geometry. DT AOD shows higher accuracy in the summer months in the northern hemisphere and evergreen broadleaf forest areas than DB AOD. The two products exhibit similar spatial distribution patterns of AOD, but higher values are seen in the DT product, especially in Asia and Western North America. The spatial completeness of the DB AOD is higher than DT, especially in brighter surface regions. In contrast, higher temporal completeness of the DT AOD is found in vegetated areas. A case study of the Western United States wildfires in 2020 indicates both products can capture extreme smoke aerosols. In addition, the DB AOD shows a distinct advantage in spatial and temporal continuity and in displaying the regional transport of smoke aerosols. However, the accuracy of the AOD retrieval for both products still needs to be improved in sparse vegetation regions, northern hemisphere summers, fine particle aerosols, and during extreme aerosol events. The overall evaluation of DB SSA and AE products shows that they are unsuitable for quantitative scientific research. This study can provide users a guide on how to select VIIRS aerosol products for different research purposes.

Universal pre-mixing dry-film stickers capable of retrofitting existing microfluidics.

Integrating microfluidic mixers into lab-on-a-chip devices remains challenging yet important for numerous applications including dilutions, extractions, addition of reagents or drugs, and particle synthesis. High-efficiency mixers utilize large or intricate geometries that are difficult to manufacture and co-implement with lab-on-a-chip processes, leading to cumbersome two-chip solutions. We present a universal dry-film microfluidic mixing sticker that can retrofit pre-existing microfluidics and maintain high mixing performance over a range of Reynolds numbers and input mixing ratios. To attach our pre-mixing sticker module, remove the backing material and press the sticker onto an existing microfluidic/substrate. Our innovation centers around the multilayer use of laser-cut commercially available silicone-adhesive-coated polymer sheets as microfluidic layers to create geometrically complex, easy to assemble designs that can be adhered to a variety of surfaces, namely, existing microfluidic devices. Our approach enabled us to assemble the traditional yet difficult to manufacture "F-mixer" in minutes and conceptually extend this design to create a novel space-saving spiral F-mixer. Computational fluid dynamic simulations and experimental results confirmed that both designs maintained high performance for 0.1 < Re < 10 and disparate input mixing ratios of 1:10. We tested the integration of our system by using the pre-mixer to fluorescently tag proteins encapsulated in an existing microfluidic. When integrated with another microfluidic, our pre-mixing sticker successfully combined primary and secondary antibodies to fluorescently tag micropatterned proteins with high spatial uniformity, unlike a traditional pre-mixing "T-mixer" sticker. Given the ease of this technology, we anticipate numerous applications for point-of-care devices, microphysiological-systems-on-a-chip, and microfluidic-based biomedical research.

GEL CASTING METHOD FOR THE PRODUCTION OF CERAMIC MATERIALS

Gel casting is one of the new and promising methods for producing ceramics. Modern research on the production of ceramic materials by gel casting covers a wide range of materials, including both dense and porous ceramic materials. The advantages of this method, such as ease of processing, the use of technological equipment of traditional methods, increased productivity, the possibility of obtaining products of large shapes and complex geometry, gave impetus to new research and development. This article provides an overview of publications devoted to research in recent decades on the production by gel casting of both dense ceramics for the manufacture of structural elements and porous ceramics for the manufacture of thermal insulation, porous filters and membranes.

Region-Aware Arbitrary-Shaped Text Detection With Progressive Fusion

Segmentation-based text detectors are flexible to capture arbitrary-shaped text regions. Due to large geometry variance, it is necessary to construct effective and robust representations to identify text regions with various shapes and scales. In this paper, we focus on designing effective multi-scale contextual features for locating text instances. Specially, we develop a Region Context Module (RCM) to summarize the semantic response and adaptively extract text-region-aware information in a limited local area. To construct complementary multi-scale contextual representations, multiple RCM branches with different scales are employed and integrated via Progressive Fusion Module (PFM). Our proposed RCM and PFM serve as the plug-and-play modules which can be incorporated into existing scene text detection platforms to further boost detection performance. Extensive experiments show that our methods achieve state-of-the-art performances on Total-Text, SCUT-CTW1500 and MSRA-TD500 datasets. The code with models will become publicly available at <uri>https://github.com/wqtwjt1996/RP-Text.</uri>

DAM BREACH ANALYSIS AND PARAMETER SENSITIVITY ANALYSIS ALONG A RIVER REACH USING HECRAS

A dam break is a low-probability, high risk catastrophe event that is extremely destructive and has a substantial negative socio-economic impact on downstream and nearby areas. Simulating dam breach and analyzing flood propagation downstream from those events is vital for identifying and minimizing the risks associated downstream of dam location. This study is intended to anlayse the effect of overtopping failure of dam for two scenario (a) base-case scenario (scenario with average value of dam breach parameters from their range) and (b) worst case scenario (the breach with largest geometry, shortest formation time and highest peak outflow magnitude). Further, a hydrodyanmic modelling is perfomed to investigate the sensitivity analysis (local and global) of five dam breach parameters (dam breach elevation, dam breach width, breach formation time, weir coefficient, trigger failure elevation) on breach outflow in a proposed hydropower project located in Nepal. Aeronautical Reconnaissance Coverage Geographic Information System (ArcGIS), Hydraulic Engineering Center River Analysis System (HEC-RAS) and OriginPro 2022b are utilized to analyse the effect of dam breach and parameter sensitivity.&#x0D; Generation of outflow hydrograph shows that worst case scenario has devasting effect downstream with innudation of 1047 of househols and 50.83 kilometers of roads. The breach velocty was recorded as 15.16 m/s and 20.85 m/s for base and worst case respectively. The minimum depth and maximum depth of flooding downstream from dam location was found to be 24.51 m and 73.6 m for base case and 47.43 m and 106.75 m for worst case. Due to backwater effect at Bheri river, peak flow at 14 km downstream from dam reduces significantly to 124852.57 m3/s and 244204.41 m3/s for base and worst case respectively. From local sensitivty analysis it has been found that, dam breach elevation is more sensitive and triggering failure elevation is less sensitive for peak outflow hydrograph. Whereas, dam breach width seems more sensitive and TFE seems least sensitive for peak outflow using Monte Carlo Simulation for gloal sensitivity.

Asymmetrically weighted graphs, asymmetric metrics and large scale geometry

Asymmetrically weighted graphs, asymmetric metrics and large scale geometry

Illumination system optimal design for geometry measurement of complex cutting tools in machine vision

Precision geometry measurement of complex cutting tools has a significant impact on the machinability of components in the industry. However, acquiring high-quality images in machine vision is a challenging problem due to the large slope and complex geometry. In view of the vital function of illumination, this paper proposed a method of optimal design for the LED array. First, the calculation model of irradiance distribution on the measurement plane is established, and the properties of the reflected light from the surface of cutting tools are analyzed based on the BRDF theory. Then, the optimal parameters are solved through the specific algorithm flow for the LED array design. Finally, a flexible LED light source is fabricated with the optimal parameters for different features of the cutting tools and used in the measurement. The measurement results show that the error of the optimized light source is less than 1%, and compared with the off-the-shelf light, the measurement accuracy is improved by 9.5% on average. Moreover, this method also presents the potential applied to other complex objects.

Laughlin States Change Under Large Geometry Deformations and Imaginary Time Hamiltonian Dynamics

We study the dependence of the Laughlin states on the geometry of the sphere and the plane, for one-parameter Mabuchi geodesic families of curved metrics with Hamiltonian \(S^1\)-symmetry. For geodesics associated with convex functions of the symmetry generator, as the geodesic time goes to infinity, the geometry of the sphere becomes that of a thin cigar collapsing to a line and the Laughlin states become concentrated on a discrete set of \(S^1\)-orbits, corresponding to Bohr–Sommerfeld orbits of geometric quantization.

Strategies towards robust interpretations of in situ zircon oxygen isotopes

Oxygen isotopes are a versatile tool to address a wide range of questions in the Earth sciences. Applications include geothermometry, paleoclimatology, tracing of geochemical reservoirs, fluid-rock interaction, magmatic petrogenesis, and identification of extra-terrestrial materials. Zircon arguably provides one of the most robust records of primary magmatic O isotope ratio due to low diffusion rates in crystalline grains. The ability to correlate zircon O isotopes with temporal and petrogenetic information (e.g. U-Pb geochronology, Lu-Hf isotopes, and trace elements) makes this mineral a key archive for understanding Earth’s crustal evolution. Consequently, zircon O isotope geochemistry has found widespread usage to address fundamental questions across the earth and planetary sciences. The general apparent ease of O isotopic acquisition through the advancement of rapid in situ techniques (i.e. secondary ion mass spectrometry; SIMS) and associated dedicated national laboratories has led to the generation of large O isotopic data sets of variable quality, highlighting the importance of a coherent workflow for data collection, reduction, and presentation. This paper presents a set of approaches for measurement, assessment, and reporting of zircon O isotope data. The focus in this contribution is on in situ analysis via secondary ion mass spectrometry using large geometry instruments, but other commonly used techniques are briefly reviewed for context. This work aims to provide an analytical framework necessary for geologically meaningful interpretation of O isotope data. In addition, we describe inherent geological (e.g. radiation-induced disturbance of the zircon O isotopic system) and analytical (e.g. fractionation due to sample topography effects) challenges and outline means to identify and avoid such issues as a prerequisite to the generation of robust primary O isotopic signatures for geological interpretation.

Study of the Oxidation Behavior of Fine-Grained Graphite ET-10 by Combining X-ray μCT with Mercury Porosimetry.

By combining X-ray micro-computed tomography with mercury porosimetry, the evolution of the oxygen supply, porous structure, mass loss and oxidized compositions were investigated to characterize the oxidation behavior of fine-grained graphite ET-10, regarding the geometry of the specimen and its oxidation temperature. Here, the porous structure and the gas flows out of and into the porous structure were comprehensively compared for two kinds of specimens-large pure graphite (D = H = 25.4 mm), oxidized at a test facility based on ASTM D7542, and small partially SiC-coated graphite (D ≈ 1 mm and H = 1.95 mm), oxidized in the bottom section of a U-type tube. The fine grains and large geometry resulted in small pores and long flow distances, which exhausted the oxygen in the small stream to the interior of the specimen, making its oxidation deviate from the kinetics-controlled regime. In addition, the well-known three-regime theory was reasonably reinterpreted regarding the oxidation of different compositions, binders and fillers. The kinetics-controlled uniform oxidation mainly oxidizing binders is restricted by their limited contents, while the rate of surface-dominated oxidation increases continuously via the consumption of more fillers. Furthermore, we proposed a new design for the test facility used for the oxidation experiment, wherein a partially shielded millimeter specimen can be oxidized in the long straight bottom section of a U-tube, and this will be discussed further in related future studies.