Geometric Components Research Articles

The Influence of Geometry on Continuous and Split Bipolar Electrochemistry Applied to Corrosion Studies

Bipolar electrochemistry provides a wireless approach for driving redox reactions and has been applied in corrosion, electrodeposition, sensing, and electrocoagulation. Despite the extensive study of the method, the significance of geometric aspects of the experimental setup still remain ill-explored, and a justification for geometries used in previous works is missing. The aim of this study is to provide information about how current/potential distributions of a split bipolar electrode in an open configuration are affected by geometric components. Through PDE-constrained optimizations, the most influential parameters are identified to be the bipolar electrode size, electrolyte height, and applied current. It is shown that a general Wagner number may be used to inform the form of the current distribution for bipolar electrochemistry but with limitations. The results also show that the current through the bipolar electrode is directly associated with cell components and higher bipolar current efficiencies will promote the primary current distribution.

Recent progress on 3D-printed gelatin methacrylate-based biomaterials for articular cartilage repair

The structure and composition of articular cartilage is complex, and its self-healing ability is limited, and thus, it is difficult to achieve ideal healing once the articular cartilage is damaged. Recently, three-dimensional (3D) printing technology has provided a new possibility for the repair of articular cartilage. Engineered cartilage tissues can be fabricated by superimposing customized inks, considering different geometric structures and components of tissues. 3D printing can be effectively used to manufacture high-precision structures with complex geometry, solving the shortcomings of traditional scaffold fabrication techniques. Gelatin methacrylate (GelMA) is modified gelatin and is currently a widely used 3D printing ink due to its photocrosslinking properties. With good biocompatibility and tunable physical properties, it can provide a good scaffold platform for cell proliferation and growth factor release. Given that the role of 3D printing technology in cartilage repair has been widely reported, this article reviews the research progress of 3D-printed GelMA-based biomaterials in articular cartilage tissue engineering. We focus primarily on how 3D printing technology addresses the existing challenges inherent to the field of articular cartilage tissue engineering. We accentuate the modifications implemented in GelMA-based 3D printing scaffolds to optimize articular cartilage regeneration. Additionally, we provide a comprehensive summary of the utilization of GelMA-based biomaterials incorporating various cells, growth factors, or other tissue components and highlight how these adaptations, in conjunction with the benefits of 3D printing technology, facilitate improvements the articular cartilage repair.

The anisotropy and friction effect in the design of 3D printed PLA parts – A case study

Additive Manufacturing, commonly known as 3D Printing, is one of the most affordable manufacturing processes for producing complex geometric components. This manufacturing process is also frequently used when it is needed to manufacture unique parts to replace degraded or damaged components and spare parts that are no longer available. In this reverse engineering process, particular attention must be given to the constitutive models of materials. The 3D printing manufacturing process usually requires a change of materials and introduces or increases the anisotropy. In addition, the complexity of part geometries and loading often requires using the finite element method to simulate their behaviour in service.Polylactic acid (PLA) is one of the materials frequently used in 3D Printing for its sustainability, affordability, and mechanical and thermal properties. In this study, a bushing of a hinged drawer support is reverse-engineered, and its in-service behaviour is simulated before it is manufactured using Tough PLA material through 3D printing. Furthermore, the effect of the anisotropy and the friction in the design is evaluated. The MSC Patran/Nastran 2021 software for the finite element analysis, the Ultimaker Cura 5.0 software and the Ultimaker S5 printer were used.

Stability analysis of f(Q) gravity models using dynamical systems

In recent years, the modified theory of gravity known as [Formula: see text] gravity has drawn interest as a potential alternative to general relativity. According to this theory, the gravitational force is determined by a function of the so-called “non-metricity” tensor [Formula: see text], which expresses how far a particle space-time is from the metric geometry. In contrast to general relativity, which describes the gravitational field using the curvature tensor, [Formula: see text] gravity builds a theory of gravity using the non-metricity tensor. For this class of theories, dynamical system analysis of the background and perturbation equations has been carried out in this work to determine how various models behave cosmologically. Here, the critical points are determined for two [Formula: see text] models from the literature: the power law, [Formula: see text], and the logarithmic, [Formula: see text] models. The stability behavior and corresponding cosmology are displayed for each critical point. For the power law model, we achieve a matter-dominated saddle point with the right matter perturbation growth rate. For the logarithmic model, we get a saddle point dominated by the geometric component of the [Formula: see text] model with perturbations in the decomposition of matter. For both models, we later achieved a stable and accelerating Universe with constant matter perturbations.

Moldflow Simulation and Characterization of Pure Copper Fabricated via Metal Injection Molding.

Metal injection molding (MIM) is a representative near-net-shape manufacturing process that fabricates advanced geometrical components for automobile and device industries. As the mechanical performance of an MIM product is affected by green-part characteristics, this work investigated the green part of pure copper processed with MIM using the injection temperature of ~180 °C and injection pressure of ~5 MPa. A computational analysis based on the Moldflow program was proposed to simulate the effectivity of the process by evaluating the confidence of fill, quality prediction, and pressure drop of three distinctive regions in the green part. The results showed that the ring and edge regions of the green parts showed localized behavior, which was related to processing parameters including the position of the gate. A microstructural observation using scanning electron microscopy and a 3D X-ray revealed that both the surface and body matrix consisted of pores with some agglomeration of micro-pores on the edges and ring part, while any critical defects, such as a crack, were not found. A microhardness analysis showed that the three regions exhibited a reasonable uniformity with a slight difference in one specific part mainly due to the localized pore agglomeration. The simulation results showed a good agreement with the microstructures and microhardness data. Thus, the present results are useful for providing guidelines for the sound condition of MIM-treated pure copper with a complex shape.

Population-based asymmetric margins for moving targets in real-time tumor tracking.

Both geometric and dosimetric components are commonly considered when determining the margin for planning target volume (PTV). As dose distribution is shaped by controlling beam aperture in peripheral dose prescription and dose-escalated simultaneously integrated boost techniques, adjusting the margin by incorporating the variable dosimetric component into the PTV margin is inappropriate; therefore, geometric components should be accurately estimated for margin calculations. We introduced an asymmetric margin-calculation theory using the guide to the expression of uncertainty in measurement (GUM) and intra-fractional motion. The margins in fiducial marker-based real-time tumor tracking (RTTT) for lung, liver, and pancreatic cancers were calculated and were then evaluated using Monte Carlo (MC) simulations. A total of 74705, 73235, and 164968 sets of intra- and inter-fractional positional data were analyzed for 48 lung, 48 liver, and 25 pancreatic cancer patients, respectively, in RTTT clinical trials. The 2.5th and 97.5th percentiles of the positional error were considered representative values of each fraction of the disease site. The population-based statistics of the probability distributions of these representative positional errors (PD-RPEs) were calculated in six directions. A margin covering 95% of the population was calculated using the proposed formula. The content rate in which the clinical target volume (CTV) was included in the PTV was calculated through MC simulations using the PD-RPEs. The margins required for RTTT were at most 6.2, 4.6, and 3.9mm for lung, liver, and pancreatic cancer, respectively. MC simulations revealed that the median content rates using the proposed margins satisfied 95% for lung and liver cancers and 93% for pancreatic cancer, closer to the expected rates than the margins according to van Herk's formula. Our proposed formula based on the GUM and motion probability distributions (MPD) accurately calculated the practical margin size for fiducial marker-based RTTT. This was verified through MC simulations.

Single and Multiple Gate Design Optimization Algorithm for Improving the Effectiveness of Fiber Reinforcement in the Thermoplastic Injection Molding Process.

Fiber reinforcement orientation in thermoplastic injection-molded components is both a strength as well as a weak point of this largely employed manufacturing process. Optimizing the fiber orientation distribution (FOD) considering the shape of the part and the applied loading conditions allows for enhancing the mechanical performances of the produced parts. Henceforth, this research proposes an algorithm to identify the best injection gate (IG) location/s starting from a 3D model and a user-defined load case. The procedure is composed of a first Visual Basic Architecture (VBA) code that automatically sets and runs Finite Volume Method (FVM) simulations to find the correlation between the fiber orientation tensor (FOT) and the IG locations considering single and multiple gates combinations up to three points. A second VBA code elaborates the results and builds a dataset considering the user-defined loading and constraint conditions, allowing the assignment of a score to each IG solution. Three geometrical components of increasing complexity were considered for a total of 1080 FVM simulations and a total computational time of ~390 h. The search for the best IG location has been further expanded by training a Machine Learning (ML) model based on the Gradient Boosting (GB) algorithm. The training database (DB) is based on FVM simulations and was expanded until a satisfactory prediction accuracy higher than 90% was achieved. The enhancement of the local FOD on the critical regions of three components was verified and showed an average improvement of 26.9% in the stiffness granted by a high directionality of the fibers along the load path. Finite element method (FEM) simulations and laboratory experiments on an industrial pump housing, injection-molded with a polyamide-66 reinforced with 30% of short glass fibers (PA66-30GF) material were also carried out to validate the FVM-FEM simulation frame and showed a 16.4% local stiffness improvement in comparison to the currently employed IG solution.

Geometrical intuition components for designing mathematical tasks

Geometrical intuition is the ability to visualize, construct, and manage geometrical shapes in the mind when solving geometry problems. Geometrical intuition requires four skills: the ability to construct and manage geometrical figures in mind, perceive geometrical properties, connect pictures to concepts and theories in geometry, and determine where and how to begin when solving geometry problems. This geometric intuition ability is important for developing problem-solving. Therefore, we need a task that can be used to identify and develop students' geometric intuition abilities. This research aims to design a geometric intuition task. We employ design research methods to design geometrical intuition tasks by conducting a literature review on geometric intuition and geometry tasks, creating geometrical intuition tasks, and estimating and noting the possible student responses. This study produced three types of tasks based on the four components of geometric intuition. We provide a list of possible responses that junior high school students may provide, as well as practical suggestions for teachers. We recommend research using our developed task to evaluate students' geometrical intuition.

Recent Developments of Femtosecond Laser Direct Writing for Meta-Optics.

Micro-optics based on the artificial adjustment of physical dimensions, such as the phase, polarization, and wavelength of light, constitute the basis of contemporary information optoelectronic technology. As the main means of optical integration, it has become one of the important ways to break through the future bottleneck of microelectronic technology. Geometric phase optical components can precisely control the polarization, phase, amplitude and other properties of the light field at the sub-wavelength scale by periodically arranging nanometer-sized unit structures. It has received extensive attention in the fields of holographic imaging and polarization optics. This paper reviews the physical mechanism of micro-nano structure modification, research progress of femtosecond laser direct-writing photoresist, femtosecond laser ablation of metal thin films, femtosecond laser-induced nanograting, and other methods for preparing polarization converters and geometric phase optics. The challenges of fabricating ultrafast optical devices using femtosecond laser technology are discussed.

Deep learning framework-based 3D shape reconstruction of tanks from a single RGB image

In recent times, complicated three-dimensional shape reconstruction from a single RGB image has become a crucial technology in many industries such as Automotive, Healthcare, and Military. It is particularly challenging to reconstruct the complex shape of a military tank. Former methods infer 3D information from 2D images via shape deformation from ellipsoids, which has the problems of local adhesion, uneven surfaces, and distortion of the structure. This study introduces a new single-view 3D shape reconstruction (SVSR) framework with multi-scale feature extraction that splits shape reconstruction into three tasks—camera parameter prediction, initial shape construction, and deformation prediction. The shape-initialization module provides a variable initial shape by predicting the stretch and displacement parameters of each geometric component based on their topological relationships. The shape-deformation module predicts the directional deformation of each vertex. These two modules are dedicated separately to avoid shape adhesion and improve the local detail performance. Silhouette images of the tank’s overall shape and local geometric components are employed to eliminate the impact of component shielding and avoid structural distortion via both pixel loss and perceptual loss. Experiments on the main battle tank dataset demonstrate that our method can predict complicated 3D shapes with a low Chamfer distance value (0.0017). Our approach outperforms the other state-of-the-art methods in terms of Chamfer distance and F-score with at least a 10% improvement, with more realistic overall contours and part details. It has huge application prospects in dealing with other complex shape predictions by modifying the shape-initialization module.

An effective geometric nonlinear analysis approach of framed structures with local material nonlinearities based on the reduced-order Newton-Raphson method

The P-Δ effect is essential to be considered in the quasi-static pushover or horizontal seismic analysis of high-rise framed structures. Owing to the presence of the P-Δ effect, however, the geometric stiffness varies with the members’ internal variables (such as axial force and relative lateral displacement). Using a conventional nonlinear analytical process, each iteration has to update the structural effective stiffness even though the material remains elastic. Consequently, it requires a tremendous amount of computational effort in the material and geometric (double) nonlinear analysis of large-scale frames. To alleviate this disadvantage, this study presents an efficient and accurate nonlinear analysis approach for the high-rise framed structure considering the P-Δ effect. Assuming an invariant (time-independent) vertical load of each storey after the gravity analysis, the structural geometric stiffness induced by the P-Δ effect is then constant. Accordingly, the conventional double nonlinear system could be converted into an equivalent material nonlinear one whose effective stiffness contains material and geometric components. After that, a reduced-order Newton-Raphson method is employed to simplify the iterative analysis of the global system into that of a reduced subsystem comprised by yielding elements. Four application cases demonstrated the accuracy and reliability of the presented geometric nonlinear analysis approach. Predictably, the presented strategy will considerably improve the efficiency of double nonlinear analysis of the tall framed structure with local material nonlinearities.

Acute renal failure and cardiac arrhythmias associated with remdesivir use in patients with COVID-19 infections: Analysis using the US FDA adverse event reporting system.

Recently, antivirals, including remdesivir, have been repurposed to treat COVID-19 infections. Initial concerns have been raised about the adverse renal and cardiac events associated with remdesivir. This study aimed to analyse the adverse renal and cardiac events associated with remdesivir in patients with COVID-19 infections using the US FDA adverse event reporting system. A case/non-case method was used to determine adverse drug events associated with remdesivir as the primary suspect drug between January 1, 2020, and November 11, 2021, for patients with COVID-19 infections. Cases were reports for remdesivir with ≥1 ADEs as preferred terms included in the Medical Dictionary of Regulatory Activities (MedDRA) system organ classes 'Renal and urinary disorders' or 'cardiac' disorders. To measure disproportionality in reporting of ADEs, frequentist approaches, including the proportional reporting ratio (PRR) and reporting odds ratio (ROR), were used. The empirical Bayesian Geometric Mean (EBGM) score and information component (IC) value were calculated using a Bayesian approach. A signal was defined as the lower limit of 95% confidence intervals of ROR ≥ 2, PRR ≥ 2, IC > 0, and EBGM > 1 for ADEs with ≥4 reports. Sensitivity analyses were undertaken by excluding reports for non-Covid indications and medications strongly associated with AKI and cardiac arrhythmias. In the main analysis for remdesivir use in patients with COVID-19 infections, we identified 315 adverse cardiac events comprising 31 different MeDRA PTs and 844 adverse renal events comprising 13 different MeDRA PTs. Regarding adverse renal events, disproportionality signals were noted for "renal failure" (ROR = 2.8 (2.03-3.86); EBGM = 1.92 (1.58-2.31), "acute kidney injury" (ROR = 16.11 (12.52-20.73); EBGM = 2.81 (2.57-3.07), "renal impairment" (ROR = 3.45 (2.68-4.45); EBGM = 2.02 (1.74-2.33). Regarding adverse cardiac events, strong disproportionality signals were noted for "electrocardiogram QT prolonged" (ROR = 6.45 (2.54-16.36); EBGM = 2.04 (1.65-2.51), "pulseless electrical activity" (ROR = 43.57 (13.64-139.20); EBGM = 2.44 (1.74-3.33), "sinus bradycardia" (ROR = 35.86 (11.16-115.26); EBGM = 2.82 (2.23-3.53), "ventricular tachycardia" (ROR = 8.73 (3.55-21.45); EBGM = 2.52 (1.89-3.31). The risk of AKI and cardiac arrythmias were confirmed by sensitivity analyses. This hypothesis-generating study identified AKI and cardiac arrhythmias associated with remdesivir use in patients with COVID-19 infections. The relationship between AKI and cardiac arrhythmias should be further investigated using registries or large clinical data to assess the impact of age, genetics, comorbidity, and the severity of Covid infections as potential confounders.

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Thermo-electro-mechanical aging and degradation of conductive 3D printed PLA/CB composite

Conductive polymeric composites consist of a polymeric matrix filled with conductive particles, providing electrical properties to a naturally insulating material. Their use in material extrusion printers provides great flexibility to geometrical design functional components. However, the degradation of their mechanical behavior during and after the application of electric currents is still absent in the literature. The flow of electric currents induces material heating affecting the strength, and mechanical deformation alters the electric properties leading to bilateral dependences. These processes evolve during the application of electric fields and may degrade the material behavior permanently. In this work, we address these questions taking as baseline material a 3D printed conductive Polylactic Acid (PLA)/ Carbon Black (CB) composite. We performed multi-physical characterizations on samples with different printing orientations and lengths evaluating: i) electric behavior under direct current (DC) regime and a wideband analysis by a Frequency Response Analysis; ii) thermo-electrical behavior studying the temperature field evolution under applied electric fields; iii) thermo-mechanical behavior under uniaxial tension for different testing temperatures; iv) thermo-electrical aging/degradation effects on the mechanical behavior. The study considers a wide range of electric fields (from 180 V/m to 600 V/m) and temperatures (from 25° to 130 °C). The results show enhanced electrical conductivity and mechanical stiffness when using a printing orientation parallel to the electro-mechanical loading. This coupled response is highly influenced by thermal effects due to Joule heating, especially when surpassing the glass transition and cold crystallization temperatures of the composite. The occurrence of such phase transitions governs the material degradation by promoting the growth of mesostructural pores during heating cycles arising from the application of electric fields. The obtained results are essential to unravel changes in mechanical properties when standing for continuous electric conduction and provide an experimental background for the lifetime expectance for the devices and possible thermo-electro-mechanical failure.

Universal Behavior of Highly Confined Heat Flow in Semiconductor Nanosystems: From Nanomeshes to Metalattices

Nanostructuring on length scales corresponding to phonon mean free paths provides control over heat flow in semiconductors and makes it possible to engineer their thermal properties. However, the influence of boundaries limits the validity of bulk models, while first-principles calculations are too computationally expensive to model real devices. Here we use extreme ultraviolet beams to study phonon transport dynamics in a 3D nanostructured silicon metalattice with deep nanoscale feature size and observe dramatically reduced thermal conductivity relative to bulk. To explain this behavior, we develop a predictive theory wherein thermal conduction separates into a geometric permeability component and an intrinsic viscous contribution, arising from a new and universal effect of nanoscale confinement on phonon flow. Using experiments and atomistic simulations, we show that our theory applies to a general set of highly confined silicon nanosystems, from metalattices, nanomeshes, porous nanowires, to nanowire networks, of great interest for next-generation energy-efficient devices.

Sphenoid Bone Determines the Curvature of the Cranial Vault in Postnatal Skull Development in C57BL/6 Mice.

The skull is a complex structure formed by the craniofacial bones' elaborate organization. The growth pattern in each craniofacial bone of the postnatal skull has been presented in wild-type mice. However, the skull's growth pattern, determined by the craniofacial bones' coordinated growth, is unfamiliar. This study aimed to examine the overall morphological change in the mid-sagittal plane of the postnatal mice's skulls and interaction between the craniofacial bones. Geometric morphometric principal component analysis was performed in the mid-sagittal plane of 31 wild-type mice's skulls from postnatal days 28 to 98. The relationship between the cranial base and cranial vault was investigated by comparing skulls with early fusion and non-fusion of intersphenoid synchondrosis (ISS). The cranial vault flattening and sphenoid bone length increased with age. The cranial vault curvature and sphenoid base length showed a positive correlation that was confirmed by comparing the skulls with early fusion and non-fusion of ISS. The sphenoid bone length and cranial vault angle significantly decreased in the skulls with early fusion of ISS compared to non-fusion skulls. It is suggested that the cranial vault flattening is sphenoid bone length-induced but cranial vault length-independent during postnatal mice skull development.

Answer to an open problem about stochastic comparison of parallel systems with geometric components

Mao and Hu [5] left an open problem about the hazard rate order between two parallel systems of n geometric components. Du et al. [3] solved the problem for n=2. Wang [6] gave the answer to the problem for n up to 9. In this short note, we solve the open problem for any n.

Cosmological tests of the osculating Barthel–Kropina dark energy model

We further investigate the dark energy model based on the Finsler geometry inspired osculating Barthel–Kropina cosmology. The Barthel–Kropina cosmological approach is based on the introduction of a Barthel connection in an osculating Finsler geometry, with the connection having the property that it is the Levi-Civita connection of a Riemannian metric. From the generalized Friedmann equations of the Barthel–Kropina model, obtained by assuming that the background Riemannian metric is of the Friedmann–Lemaitre–Robertson–Walker type, an effective geometric dark energy component can be generated, with the effective, geometric type pressure, satisfying a linear barotropic type equation of state. The cosmological tests, and comparisons with observational data of this dark energy model are considered in detail. To constrain the Barthel–Kropina model parameters, and the parameter of the equation of state, we use 57 Hubble data points, and the Pantheon Supernovae Type Ia data sample. The st statistical analysis is performed by using Markov Chain Monte Carlo (MCMC) simulations. A detailed comparison with the standard Lambda CDM model is also performed, with the Akaike information criterion (AIC), and the Bayesian information criterion (BIC) used as the two model selection tools. The statefinder diagnostics consisting of jerk and snap parameters, and the Om(z) diagnostics are also considered for the comparative study of the Barthel–Kropina and Lambda CDM cosmologies. Our results indicate that the Barthel–Kropina dark energy model gives a good description of the observational data, and thus it can be considered a viable alternative of the Lambda CDM model.

The Geometric Redesign of Horizontal Curved Using AutoCAD Civil 3D®: A Case Jalan Garuda – Jalan Moh. Hatta, Tasikmalaya West Java

Highways are needed because they are the most widely used transportation infrastructure to support the economy and daily human activities that function to pass traffic on it quickly, safely, and comfortably. In today's world of rapid digital improvement, road planning using AutoCAD Civil 3D® results in a more efficient, accurate, and time-saving road planning process than road planning using manual methods. The horizontal alignment of the road determines the location of the road in question. The horizontal alignment has three geometric components: tangent, curve, and transition between straight line and arch. The purpose of writing this paper is to plan the geometric road on the North Ring Road section Jalan Garuda - Jalan Moh. Hatta in the northern area of Tasikmalaya, West Java. The road is planned to add land transportation facilities and connect the Cibeureum District - Cipedes District. The length of the road section is 1016 m or 1,016 km (STA 0+000 – STA 1+016.79).

Analysis of the nervous system and gastrointestinal adverse events associated with solifenacin in older adults using the US FDA adverse event reporting system.

Antimuscarinics are the backbone of the pharmacological management of overactive bladder. Still, concerns have been raised over the nervous system (NS) adverse drug events (AEs) due to their dissimilarities to muscarinic receptor-subtype affinities. This study aimed to identify the nervous system and gastrointestinal adverse drug events (ADEs) associated with solifenacin use in older adults (≥65 years). A case/non-case analysis was performed on the reports submitted to the FDA Adverse Event Reporting System (FAERS) between 01/01/2004 and 30/06/2020. Cases were reports for solifenacin with ≥1 ADEs as preferred terms included in the Medical Dictionary of Regulatory Activities (MedDRA) system organ classes 'nervous system' or 'gastrointestinal' disorders. Non-cases were all other remaining reports for solifenacin. The case/non-cases was compared between solifenacin and other bladder antimuscarinics. Frequentist approaches, including the proportional reporting ratio (PRR) and reporting odds ratio (ROR), were used to measure disproportionality. The empirical Bayesian Geometric Mean (EBGM) score and information component (IC) value were calculated using a Bayesian approach. A signal was defined as the lower limit of 95% confidence intervals of ROR ≥2, PRR ≥2, IC >0, EBGM >1, for ADEs with ≥4 reports. 107 MedDRA preferred terms (PTs) comprising 970 ADE reports were retrieved for nervous system disorders associated with solifenacin. For gastrointestinal disorders, 129 MedDRA PTs comprising 1817 ADE reports were retrieved. Statistically significant results were found for 'altered state of consciousness': ROR = 9.71 (2.13-44.35), PRR = 9.69 (2.12-44.2) and IC = 1.29 (0.93-1.66). The disproportionality reporting of 'altered state of consciousness', a previously unidentified ADE, was unexpected. Further monitoring of this ADE is needed to ensure patient safety, as this could be linked to poor balance and falls in older adults.