Perfect Circularity Research Articles

High-Sensitivity Polarization Sensitive Optical Coherence Tomography Based on Numerical Correction for Perfect Circularly Polarized Light

Polarization sensitive optical coherence tomography (PSOCT) makes use of the birefringence information of the sample to compensate for the lack of internal tissue-specific contrast in conventional optical coherence tomography (OCT). Circularly polarized light is always used as an incident beam in PSOCT, but it is difficult to have perfect in practice. The manual calibration method of circularly polarized light suffers from the problems of complicated calibration operation and lack of stability. This study proposes a simple method to enhance the imaging of PSOCT without altering the system. A numerical calibration of circularly polarized light can be implemented using the original system setup, ensuring that the system’s complexity remains unchanged. Enhancements in imaging quality can be achieved through an algorithmic analysis of the captured interference fringe data. This calibration is applied in the field map of interference data before being quadrature-assembled. Notably, the proposed approach achieves high sensitivity in PSOCT. The birefringence image shows a more obvious layered structure. Improvements in the signal-to-noise ratio (SNR) were demonstrated for chicken breast, pork, and beef imaging at about 20 dB.

Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters

This Letter presents a study of the geometry and motion of the Galactic disk using open clusters in the Gaia era. The findings suggest that the inclination θ i of the Galactic disk increases gradually from the inner to the outer disk, with a shift in orientation at the Galactocentric radius of approximately 6 ± 1 kpc. Furthermore, this study brings forth the revelation that the mid-plane of the Milky Way may not possess a stationary or fixed position. A plausible explanation is that the inclined orbits of celestial bodies within our Galaxy exhibit a consistent pattern of elliptical shapes, deviating from perfect circularity; however, more observations are needed to confirm this. An analysis of the vertical motion along the Galactocentric radius reveals that the disk has warped with precession and that the line of node shifts at different radii, aligning with the results from the classical Cepheids. Although there is uncertainty for precession/peculiar motion in solar orbit, after considering the uncertainty, the study derives a median value of = 6.8 km s−1 kpc−1 in the Galaxy. This value for the derived precession in the outer disk is lower than those in the literature due to the systematic motion in solar orbit (θ i = 0.°6). The study also finds that the inclinational variation of the disk is significant and can cause systematic motion, with the variation rate decreasing along the Galactic radius with a slope of −8.9 μas yr−1 kpc−1. Moreover, the derived in solar orbit is 59.1 ± 11.2sample ± 7.7 μas yr−1, which makes it observable for high-precision astrometry.

Effect of Ovality on the Buckling Behavior of Thin-Walled Liquid-Filled Conical Tanks

This study investigates the influence of ovality on the buckling behavior of thin-walled liquid-filled conical tanks through comprehensive numerical simulations. The structural stability of conical tanks is of paramount importance in various engineering applications, such as storage vessels and aerospace structures. However, the presence of ovality, characterized by deviations from perfect circularity, can significantly affect the structural response and integrity of these tanks. To explore the effects of ovality, a finite element analysis (FEA) approach is employed, considering various ovality levels in the tank geometry. A comprehensive parametric study is conducted, varying key parameters such as tank dimensions, material properties, and liquid filling levels. The buckling behavior of the tanks is assessed by examining critical buckling loads and corresponding deformation modes. Results from the numerical simulations reveal that even small levels of ovality can substantially reduce the buckling load capacity of conical tanks. As ovality increases, the onset of buckling occurs at lower applied loads, leading to premature structural failure. The presence of liquid filling further exacerbates the buckling phenomenon, with the liquid sloshing effect amplifying the structural response. The study also investigates the influence of different materials on the buckling behavior of conical tanks subjected to ovality. It is found that the material stiffness and yield strength play a crucial role in determining the critical buckling load and mode shape. Furthermore, the effect of liquid fill level is explored, demonstrating that higher fill levels increase the vulnerability to buckling.

Estimating the Circularity Performance of an Emerging Industrial Symbiosis Network: The Case of Recycled Plastic Fibers in Reinforced Concrete

In recent times, the construction industry has been handling circular economy strategies in order to face the most important challenges in the sector, namely the lack of raw materials and the environmental impacts derived from all the processes linked to the entire supply chain. The industrial symbiosis approach represents an effective strategy to improve the circularity of the construction industry. This study analyses the circularity performance of an emerging industrial symbiosis network derived from the production of a cement mortar reinforced with recycled synthetic fibers coming from artificial turf carpets. From the collection of artificial turf carpets at the end-of-life stage it is possible to recover several materials, leading to potential unusual interactions between industries belonging to different sectors. A suitable indicator, retrieved from the literature, the Industrial Symbiosis Indicator (ISI), has been used to estimate the level of industrial symbiosis associated with increasing materials recirculation inside the network. Four scenarios—ranging from perfect linearity to perfect circularity—representing growing circularity were tested. Findings demonstrate that the development of an effective industrial symbiosis network can contribute to improving the circular approach within the construction sector, reducing environmental and economic pressures.

All-dielectric transmission type three-frequency linearly polarized to circularly polarized converter

In this article, a transmissive three-frequency linearly polarized (LP) wave to circularly polarized (CP) wave metasurface is designed using all-dielectric materials. The structure is composed of a cross-shaped bar resonator and a split circular ring resonator. Numerical simulations results show that when the LP wave is incident on the device, it will be converted into nearly perfect right-handed circularly polarized (RHCP), left-handed circularly polarized and RHCP waves at 2.2146, 2.2467 and 2.3144 THz. The distribution of the conduct current, electric field and magnetic field are investigated to explain the physical mechanism. And the influence of the structural parameters and different incident angles for the structure are also studied in the end.

Laser process parameter optimization of dimple created on oriented carbon fiber reinforced epoxy composites

It was mainly aimed at the study to make the optimization of laser parameters to obtain dimples with the desired shape and size. Carbon Fiber EPOXY composite (CF-EPOXY) surfaces were ablated by Nd:YAG laser which has a 1064 nm wavelength. Some important laser process parameters such as focus position, pulse energy, duration and number were optimized to achieve maximum aspect ratio, circular shape and minimum thermal defect. In addition, it has been determined that which laser parameters are more effective to obtain the desired quality surface. These different shapes and geometry of dimples could be used to improve some properties such as wettability, friction, etc. The pulse energy with an effective rate of 55.97 % is the most effective parameter to achieve the larger aspect ratio. The focus position is the most effective parameter with the rates of 66.18 % and 47.94 % to obtain both perfect circularity and minimum thermal defects respectively. Confirmation experiments were performed and the highest aspect ratio was found as 1.14, the best circular dimple and the minimum thermal effects outside the spot area were found with the rates of 1.021. These are the optimum results of 9 experiment sets in this study for each output. The results were supported by confirmation experiments and regression analysis. It can be concluded that the Taguchi method is reliable and saves time and materials.

Co-culture of pro-inflammatory macrophages and myofibroblasts: Evaluating morphological phenotypes and screening the effects of signaling pathway inhibitors.

Skeletal muscle regeneration is a complex process influenced by non‐myogenic macrophages and fibroblasts, which acquire different phenotypes in response to changes in the injury milieu or changes in experimental conditions. In vitro, serum stimulates the differentiation of fibroblasts into myofibroblasts, while lipopolysaccharide (LPS) stimulates the polarization of unstimulated (M0) macrophages to acquire an M1 pro‐inflammatory phenotype. We characterized these phenotypes using morphology (with circularity as shape descriptor; perfect circularity = 1.0) and phenotype‐specific markers. Myofibroblasts (high α‐smooth muscle actin [SMA] expression) had high circularity (mean 0.60 ± 0.03). Their de‐differentiation to fibroblasts (low α‐SMA expression) significantly lessened circularity (0.47 ± 0.01 and 0.35 ± 0.02 in 2% or 0% serum culture media respectively (p < 0.05). Unstimulated (M0) macrophages (no CD86 expression) had high circularity (0.72 ± 0.02) which decreased when stimulated to M1 macrophages (CD86 expression) (LPS; 0.61 ± 0.02; p < 0.05). Utilizing these established conditions, we then co‐cultured M1 macrophages with myofibroblasts or myoblasts. M1 macrophages significantly decreased relative myofibroblast numbers (from 223 ± 22% to 64 ± 7%), but not myoblast numbers. This pro‐inflammatory co‐culture model was used to rapidly screen the following four compounds for ability to prevent M1 macrophage‐mediated decrease in myofibroblast numbers: L‐NAME (inducible nitric oxide synthase inhibitor), SB203580 (p38 mitogen‐activated protein kinase inhibitor), SP600125 (c‐Jun N‐terminal kinase inhibitor) and LY294002 (phosphoinositide 3‐kinase [PI3K] inhibitor). We found that LY294002 rescued myofibroblasts and decreased macrophage numbers. Myofibroblast rescue did not occur with L‐NAME, SB203580 or SP600125 incubation. In conclusion, these data suggest a PI3K‐associated mechanism whereby myofibroblasts can be rescued, despite simulated pro‐inflammatory conditions.

Evaluation of the resource effectiveness of circular economy strategies through multilevel Statistical Entropy Analysis

In a circular economy (CE), materials, components and products should be kept at the highest level of functionality, while phenomena like dilution, mixing and contamination, often referred to as the loss of resources, should be avoided. One method that can assess the performance of systems to concentrate or avoid dilution of resources is Statistical Entropy Analysis (SEA). Up till now, the method has been applied on the substance level (elements and compounds) only, but showed its applicability to various scales and a variety of systems. Further development of the method allowed to consider information on the product, component and material levels, which makes the method applicable to different combinations of CE strategies, both destructive (e.g. recycling) and non-destructive (e.g. reuse). The method is demonstrated on a simplified vehicle life-cycle, which is modeled through four component groups and six materials. It shows that the method allows to evaluate different CE strategies and identify critical stages which lead to the most severe resource and functionality losses. Based on the method's results, it is possible to determine a perfect circularity reference level, representing a system state that preserves functionality and avoids resource losses. The introduction of a circularity reference level enables the establishment of a framework for resource effectiveness in which diluting and concentrating effects of activities (e.g. sorting) are quantified. The distance of a system to an ideal circular state determines the deviation from a resource-effective system that maintains the original product functionality over a maximum period of time, with minimal efforts.

Chemically oscillating reactions in the formation of botryoidal malachite

Abstract The origin of banding patterns in malachite [Cu2CO3(OH)2] is an enduring problem in geology. While the bright green, vivid colors of this mineral have been attributed to the presence of Cu, no specific process has been proposed that can explain the perfect circularly concentric banding and geometrical shapes in botryoidal malachite. These patterns of concentric equidistant laminations are comparable to those arising from chemically oscillating experiments using the classical reactants of the Belousov-Zhabotinsky (B-Z) reaction. Through optical microscopy and micro-Raman imaging, this contribution documents that the geometric centers of the self-similar geometric patterns are often composed of organic matter. Carbon isotopes and trace elements further suggest that non-biological decarboxylation reactions of biological organic matter took place during diagenesis. Hence, the morphological and chemical characteristics of chemically oscillating reactions offer a plausible explanation for the formation of botryoidal malachite and abiotic environmental decarboxylation reactions.

Circular-polarization-sensitive absorption in refractory metamaterials composed of molybdenum zigzag arrays.

Circularly polarized light (CPL) is utilized in various fields, including optical communication and biological imaging. To overcome the lack of circular-polarization-sensitive absorbers working at high temperature, a refractory and circular-polarization-sensitive absorber comprised of molybdenum zigzag arrays is proposed. At certain resonant wavelengths, one component of circular polarization is absorbed by confining electromagnetic field in the dielectric layer, while the other component is backscattered. The circular-polarization-sensitive absorber could be applied as a CPL thermal radiator as well as a reflective linear-to-circular polarizer. As a CPL thermal radiator, left-handed circular radiation and right-handed circular radiation are dominant at different temperatures, respectively. As a linear-to-circular polarizer, both perfect left-handed circularly polarized light and nearly perfect right-handed circularly polarized light are obtained.

Perfect balance and circularly rich words

A recent article [Milne, Andrew J., David Bulger, and Steffan A. Herff. 2017. “Exploring the Space of Perfectly Balanced Rhythms and Scales.” Journal of Mathematics and Music 11 (2):101--133] posits the notion of balance and contrasts it with evenness, which may be associated with the patterns of step intervals in either maximally even sets or well-formed scales. Scales defined as “perfectly balanced” are optimal in this regard. In this paper, we propose that perfectly balanced scales that display circular palindromic “richness” and also exhibit relatively few step “differences” may prove to be advantageous from a cognitive and musical perspective. For context, all circularly rich sets among 5-, 6-, and 7-note sets in 12-TET are identified. Finally, the minimal perfectly balanced sets in divisions of 30, 42, and 70 identified in Milne, Bulger, and Herff (2017) above are examined for the two constraints proposed here.

Advances in III‐nitride semiconductor microdisk lasers

This paper reviews the recent progress in the design and fabrication strategies of III‐nitride semiconductor microdisk lasers on sapphire or Si substrates. Involving more accurate lithography methods in the fabrication boosts quality factors (Q‐factors) due to the improved optical confinement of whispering‐gallery modes (WGMs) at the rim of the microdisks with smooth sidewalls and perfect circularity. Quantum dots (QDs) as gain medium within the microdisks are investigated and promising for the demonstration of micro‐lasers with super‐high Q‐factors and ultra‐low thresholds. And these QD‐cavity systems are also facilitating the research of cavity quantum electrodynamics (QED) in the strong coupling regime and cavity‐enhanced single photon emission (SPE) for quantum computing. In this paper, we also report successful fabrication of transferred GaN free‐standing microdisks with InGaN quantum wells (QWs) on conductive substrates, which achieves a significant step forward to realize electrically pumped high‐quality microdisk lasers on target substrates. Strategies of applying flexible transparent electrodes such as graphene and metallic nanowires are potential effective solutions for realizing current‐injection of nitride‐based microdisks.

High-efficiency generation of circularly polarized light via symmetry-induced anomalous reflection

Great efforts have been devoted to control the polarization state, the transmission direction, and the phase of light within a very confined space in recent decades. Here, we present a two-dimensional metastructure made of an array of unisized split rings with different opening orientations on the surface of a $\mathrm{Si}{\mathrm{O}}_{2}$-silver bilayer. This structure possesses an unexpectedly high polarization conversion ratio and generates significantly strong anomalous reflection beams (over 70% of incident light intensity) over a broad frequency range (1100--1750 nm). Functionally, it is able to turn either a linearly polarized incident light or natural light into two perfect circularly polarized beams with the same amplitude yet different handedness to different directions. These features demonstrate a clear example of momentum conservation and can be applied to detect/manipulate the propagation of circularly polarized light.

Dynamically Tunable Plasmonic Lens between the Near and Far Fields Based on Composite Nanorings Illuminated with Radially Polarized Light

We present a plasmonic lens with a dynamically tunable focal length in the mid-infrared region that is composed of gold film with annular slits and embedded vanadium dioxide (VO2) nanorings. When illuminated with radially polarized light, a perfect circularly symmetric focusing spot can be dynamically tuned between the near and far fields by decreasing temperature, and it can always be focused beyond the diffraction limit. A physical model of the tunable plasmonic lens is also proposed to explain the mechanisms by which the focal length is dynamically tuned. The field enhancement and the focal length can be further tuned by adding concentric annular slits and VO2 nanorings, respectively, while keeping the focusing spot size small. This provides a further step in the development of a perfect tunable plasmonic lens.

Poetic Thickness

The purpose of this article is to demonstrate that the experience of a poem qua poem is an experience of poetic thickness, i.e. an experience in which poetic form and poetic content are inseparable. I present a critical analysis of A. C. Bradley’s ‘Poetry for Poetry’s Sake’ lecture in Section 1, indicating both the strengths and weaknesses of his conception of resonant meaning. Section 2 draws on subsequent work by I. A. Richards and Peter Lamarque to advance my account of the relationship in question, poetic thickness, understood as a demand made of a poem rather than a property discovered therein. In Sections 3–6 I discuss four objections to form-content unity from Peter Kivy: perfect circularity, ubiquitous unity, the sugar-coated pill tradition, and the defence from tradition. I show that all these objections fail against poetic thickness. I conclude that the experience of a poem qua poem is indeed an experience of thickness, and that poetic thickness is therefore a necessary condition of poetry.

La critique de l’univers de Peurbach développée par Albert de Brudzewo a-t-elle influencé Copernic ? Un nouveau regard sur les réflexions astronomiques au XVe siècle

In 1454 Georg Peurbach teaches astronomy at the Collegium Civium in Wien by reading a work of his own: the Theoricae novae planetarum. Intended to replace the old Theorica planetarum communis which had dominated the mediaeval culture, this new book is very soon adopted in the major universities of Europe and enjoys a broad diffusion being published, studied and taught up to the middle of the 17th century. Among the numerous commentaries which have been preserved -both in manuscript and printed form- the tradition of the Cracow University, started by Albert of Brudzewo, distinguishes itself because it submit Peurbach’s contribution to a subtle critique which, while recognizing the merits to which its large acceptance is due, focuses also its limits. In the name of the reality of the celestial world, Brudzewo critiques the presence, in the universe of the Theoricae, of abstract entities like the equant and the mean apogee, to which the uniformity of the movements must be referred according to an active interaction with the “real” orbs. In the name of the celestial perfection, he grasps the weaknesses and incoherences of Peurbach’s universe and arrives, ultimately, to question this point of view which acts as the mean between the real celestial world and the way it appear to an observer. In this paper, I will try to show that what was strongly supported by Brudzewo as a requirement which must be respected -i.e. the perfect uniformity and circularity of celestial movements- becomes, in Copernicus, the reason to research an alternative solution: “a more reasonable model composed of circles from which every apparent irregularity would follow while everything in itself moved uniformly, just as the principle of perfect motion requires”. So, the better known among the students of the Cracow school proves that it is not only possible, but even necessary to make astronomy from a new point of view.

Implementation of 2D explicit depth extrapolation FIR digital filters for 3D seismic volumes using singular value decomposition

We propose a new scheme for implementing predesigned 2D complex-valued wavefield extrapolation finite impulse response (FIR) digital filters, which are used for extrapolating 3D seismic wavefields. The implementation is based on singular value decomposition (SVD) of quadrantally symmetric 2D FIR filters (extrapolators). To simplify the SVD computations for such a filter impulse response structure, we apply a special matrix transformation on the extrapolation FIR filter impulse responses where we guarantee the retention of their wavenumber phase response. Unlike the existing 2D FIR filter implementation methods that are used for this geophysical application such as the McClellan transformation or its improved version, this implementation via SVD results in perfect circularly symmetrical magnitude and phase wavenumber responses. In this paper, we also demonstrate that the SVD method can save (depending on the filter size) more than 23% of the number of multiplications per output sample and approximately 62% of the number of additions per output sample when compared to direct implementation with quadrantal symmetry via true 2D convolution. Finally, an application to extrapolation of a seismic impulse is shown to prove our theoretical conclusions.

Designing stable extrapolators for explicit depth extrapolation of 2D and 3D wavefields using projections onto convex sets

We have developed a robust algorithm for designing explicit depth extrapolation operators using the projections-onto-convex-sets (POCS) method. The operators are optimal in the sense that they satisfy all required extrapolation design characteristics. In addition, we propose a simple modification of the POCS algorithm (modified POCS, or MPOCS) that further enhances the stability of extrapolated wavefields and reduces the number of iterations required to design such operators to approximately 2% of that required for the basic POCS design algorithm. Various synthetic tests show that 25-coefficient 1D extrapolation operators, which have 13 unique coefficients, can accommodate dip angles up to 70°. We migrated the SEG/EAGE salt model data with the operators and compare our results with images obtained via extrapolators based on modified Taylor series and with wavefield extrapolation techniques such as phase shift plus interpolation (PSPI) and split-step Fourier. The MPOCS algorithm provides practically stable depth extrapolators. The resulting migrated section is comparable in quality to an expensive PSPI result and visibly outperforms the other two techniques. Strong dips and subsalt structures are imaged clearly. Finally, we extended the 1D extrapolator design algorithm, using MPOCS for 2D extrapolation, to the 2D case to perform 3D extrapolation; the result is a perfect circularly symmetric migration impulse response.

Chip-Firing and Rotor-Routing on $\mathbb{Z}^d$ and on Trees

The sandpile group of a graph $G$ is an abelian group whose order is the number of spanning trees of $G$. We find the decomposition of the sandpile group into cyclic subgroups when $G$ is a regular tree with the leaves are collapsed to a single vertex. This result can be used to understand the behavior of the rotor-router model, a deterministic analogue of random walk studied first by physicists and more recently rediscovered by combinatorialists. Several years ago, Jim Propp simulated a simple process called rotor-router aggregation and found that it produces a near perfect disk in the integer lattice $\mathbb{Z}^2$. We prove that this shape is close to circular, although it remains a challenge to explain the near perfect circularity produced by simulations. In the regular tree, we use the sandpile group to prove that rotor-router aggregation started from an acyclic initial condition yields a perfect ball.

Q spoiling and directionality in deformed ring cavities

A ray-optics model is developed to describe the spoiling of the high-Q (whispering gallery) modes of ring-shaped cavities as they are deformed from perfect circularity. A sharp threshold is found for the onset of Q spoiling as predicted by the Kolmogorov-Arnol'd-Moser (KAM) theorem of nonlinear dynamics. Beyond the critical deformation b(c), Q ~ (b - b(c))(-alpha), alpha asymptotically equal to 2.4-2.6. The escaping light emerges in certain specific directions, which may be predicted.