Elliptical Structure Research Articles

Development of elliptic core-shell nanoparticles with fluorinated surfactants for 19F MRI.

Perfluorocarbon-encapsulated silica nanoparticles possess attractive features such as biological inertness and favorable colloidal properties for bioimaging with fluorine magnetic resonance imaging (19F MRI). Herein, a series of elliptic shaped silica nanoparticles with perfluorocarbon liquid perfluoro-15-crown-5 ether as core (PFCE@SiO2) were synthesized using fluorinated surfactants N-(perfluorononylmethyl)-N,N,N-trimethylammonium chloride (C10-TAC) and N-(perfluoroheptylmethyl)-N,N,N-trimethylammonium chloride (C8-TAC). The nanoparticles are characterized to obtain elliptic core-shell structures. PFCE@SiO2 showed strong 19F NMR signals of the encapsulated PFCE, indicating the potential as a highly sensitive 19F MRI probe. These elliptic PFCE@SiO2 nanoparticles provide a new option of 19F MRI probe with a morphology different from conventional nanospheres.

Analysis of pore-fracture structure evolution and permeability in tar-rich coal under high-temperature pyrolysis using μCT technology

To study the internal evolution characteristics of tar-rich coal under high-temperature pyrolysis and improve pyrolysis efficiency, three-dimensional reconstruction and analysis of tar-rich coal from northern Shaanxi after high-temperature pyrolysis were conducted using μCT technology. The evolutionary development of pore and fracture structure at different temperatures and the relationship between pore-fractures and permeability was studied and discussed. The results show that when tar-rich coal from 300 to 600 °C, it mainly undergoes two stages: in the first stage, the internal substance structure of the coal mainly undergoes thermal cracking, forming large fracture bands; in the second stage, the coal undergoes intense pyrolysis reactions, resulting in primarily circular or elliptical large pore structures within the coal, with a reduction in the number of fractures. Furthermore, a strong exponential relationship is exhibited between the porosity and permeability of tar-rich coal, and a predictive equation is provided. When the temperature exceeds 500 °C, the coupled effect of pores and fractures contributes more than 20% to permeability, and its impact cannot be ignored.

Highly sensitive and easy-to-attach wearable sensor for measuring finger force based on curvature changes in an ellipse-shaped finger ring

Technologies for digitizing worker actions to enhance human labor tasks, mitigate accidents, and prevent disabling injuries have garnered significant attention. This study focuses on monitoring the force exerted by the fingers and developing a wearable fingertip force sensor based on a simple elliptical ring structure in conjunction with a commercially available resistive bend sensor. Resembling a ring accessory, the sensor is easy to attach and detach, and exhibits high sensitivity, with a resistance change of approximately 9% for a fingertip load of 1 N. Furthermore, to mitigate crosstalk during finger flexion, we propose a combined configuration employing this ring-shaped sensor alongside another sensor designed for measuring and rectifying finger flexion angles. Additionally, we introduce an empirically derived fitting function and a straightforward calibration procedure to extract the function’s parameters. The proposed system achieves an average RMS error of 0.53 N for force estimations of approximately 5 N, even during finger flexion and postural changes.

Propagation of elliptical Gaussian vortex beam based on angular spectrum representation

Vortex beams with hollow elliptical ring structure have attracted broad interest in applications such as micro-particle trapping and manipulation. The paper investigates the dependence of the hollow elliptic ring structure of vortex beams on the beam order and the topological charge, while propagating in the near- and far-field zones. The electric field of the beam is formulated by using the angular spectrum method, which satisfies rigorously Maxwell's equation. The electric field, linear momentum and orbital angular momentum are calculated. Numerical results show that the hollow elliptical ring structure approximately remains unchanged over a finite propagation distance, accompanied by a rotation whose angle depends on the topological charge. In the far-field zone, the ring structure is broken, leading to two bright spots and several dark islands. It is found that the beam profile in the near-field zone is mainly related to the beam order but in the far-field zone is primarily affected by the topological charge. The results presented in the paper may be useful in predicting and explaining the interaction between the elliptic hollow Gaussian vortex beam and the micro-particles, such as the movement of micro-particles along the orbit and the rolling rotation.

Distributed Learning for Principal Eigenspaces without Moment Constraints

Distributed Principal Component Analysis (PCA) has been studied to deal with the case when data are stored across multiple machines and communication cost or privacy concerns prohibit the computation of PCA in a central location. However, the sub-Gaussian assumption in the related literature is restrictive in real application where outliers or heavy-tailed data are common in areas such as finance and macroeconomics. In this article, we propose a distributed algorithm for estimating the principal eigenspaces without any moment constraints on the underlying distribution. We study the problem under the elliptical family framework and adopt the sample multivariate Kendall’s tau matrix to extract eigenspace estimators from all submachines, which can be viewed as points in the Grassmann manifold. We then find the “center” of these points as the final distributed estimator of the principal eigenspace. We investigate the bias and variance for the distributed estimator and derive its convergence rate which depends on the effective rank, eigengap of the scatter matrix and the number of submachines. We show that the distributed estimator performs as if we have full access to the whole data. Simulation studies show that the distributed algorithm performs comparably with the existing one for light-tailed data, while showing great advantages for heavy-tailed data. We also extend the distributed algorithm to cases with limited communication constraints and with elliptical factor structure. Thorough simulation studies and a real application to a macroeconomic dataset verify the advantages of the proposed distributed algorithms. Supplementary materials for this article are available online.

Research on Deployable Wings for MAVs Bioinspired by the Hind Wings of the Beetle Protaetia brevitarsis.

Deployable hind wings of beetles led to a bio-inspired idea to design deployable micro aerial vehicles (MAVs) to meet the requirement of miniaturization. In this paper, a bionic deployable wing (BD-W) model is designed based on the folding mechanism and elliptical wing vein structure of the Protaetia brevitarsis hindwing, and its structural static and aerodynamic characteristics are analyzed by using ANSYS Workbench. Finally, the 3D-printed bionic deployable wing was tested in a wind tunnel and compared with simulation experiments to explore the effects of different incoming velocity, flapping frequency, and angle of attack on its aerodynamic characteristics, which resulted in the optimal combination of the tested parameters, among which, the incoming velocity is 3 m/s, the flapping frequency is 10 Hz, the angle of attack is 15°, and the lift-to-drag ratio of this parameter combination is 4.91. The results provide a theoretical basis and technical reference for the further development of bionic flapping wing for MAV applications.

Thermal storage performance of a novel shell-and-tube latent heat storage system: Active role of inner tube improvement and fin distribution optimization

This study presents a numerical analysis of the melting process in a shell-and-tube latent heat thermal energy storage (LHTES) system, featuring a twisted elliptical inner tube with annular fins. Utilizing paraffin as the phase change material (PCM) and water as the heat transfer fluid (HTF), this research examines the impact of varying twist degrees, fin quantity and fin distribution on the system's thermal performance during melting process. The analysis of the melting process includes complete melting time, temperature, and the contour of the solid-liquid interface. Notably, the study identifies that both fin quantity and distribution play a significant role in the melting process. The findings indicate that an optimal configuration, comprising a 720° twisted degree, 11 fins, and a base number a of 0.80, enhances the melting efficiency of the LHTES system by 156.44 % and reduces ineffective heat loss by 41.36 %. These results highlight the potential advantages of the twisted elliptical inner tube structure and propose an innovative approach with an exponentially non-uniform fin distribution, marking an advancement in the field of thermal energy storage.

An excellent super-polarization-independent optical directional coupler based on dual-core photonic crystal fibre with a bandwidth of 390 nm

In this work, a novel structure of dual-core photonic crystal fibre (PCF) is proposed to realize the super-polarization-independent optical directional coupler, based on the feasibility of optical fibre manufacturing process and the need of practical application into account. The introduced fluorine-doped elliptical cores with a rotation angle of 45 degrees successfully realize the super-polarization-independent coupling performance within the effective wavelength range of 1230–1620 nm, with a difference in coupling ratios between two polarized lights of less than 0.004%. In other words, it counteracts the negative effects of the introduction of dual cores on the structure’s symmetry. This greatly reduces the difference in coupling ratio between the two polarization states and effectively eliminates the polarization-dependence of the dual-core PCF. In addition, when compared to traditional elliptical air holes, the solid elliptical structure offers greater ease of control, making manufacturing less challenging. Consequently, this innovative structure is poised for widespread adoption in today’s optical communication networks.

Soliton transformation in a cold Rydberg atomic system

This work presents a method for achieving soliton transformation in a cold Rydberg atomic system to enable the realization of diverse optical potentials. Our investigation demonstrates that this system can generate various solitons, including Gaussian, elliptical, ring, and necklace structures, based on different optical lattice potentials. Additionally, stable transitions from Gaussian profile to three other profiles can be achieved either abruptly or gradually by adjusting the centers and modulation depths of potentials along the direction of light propagation. These findings highlight the versatility of this system for generating and manipulating solitons. The ability to control soliton transformation offers prospects for various applications, including all-optical switching, optical information processing, and other areas.

Episodicity in accretion-ejection processes associated with IRAS 15398-3359

The protostar is associated with a bipolar molecular outflow ejected in an nearly northeast-southwest (NE-SW) direction, which has been extensively studied. Previous episodic accretion events have been suggested by this source. Furthermore, the analysis of the morphology and kinematics of the molecular outflow revealed the presence of four bipolar elliptical shock-like structures identified in both lobes. These structures seem to trace different ejections inclined sim 10 from each other on the plane of the sky. This led to the hypothesis that the outflow axis likely precesses and launches material episodically. Since several authors reached the conclusion of the same episodicity scenario by independent observations has become an ideal target to empirically analyze the relationship between accretion and ejection processes. We analyzed ALMA archive observations in Band 6, revealing the presence of low-velocity ($<3.5$ emission from the line to the south and north of the protostar. We studied the morphology and kinematics of the gas; our study seems to support the hypothesis of a precessing episodic outflow. The ALMA observations reveal a north-south (N-S) outflow most likely associated with the protostellar system. This outflow could be older than the well-studied NE-SW outflow. The orientation of the N-S outflow is 50 on the plane of the sky away from that of the NE-SW outflow. We also analyzed the spectral energy distribution of a far away young star and preliminarily discard it as the driver of the SE outflow remnants. The new observations support the hypothesis of strong episodic accretion-ejection events in accompanied by dramatic changes in the orientation of its ejection axis, implying that all the outflows in the region may have been driven by the same protostar.

Derived Equivalence for Elliptic K3 Surfaces and Jacobians

Abstract We present a detailed study of elliptic fibrations on Fourier-Mukai partners of K3 surfaces, which we call derived elliptic structures. We fully classify derived elliptic structures in terms of Hodge-theoretic data, similar to the Derived Torelli Theorem that describes Fourier-Mukai partners. In Picard rank two, derived elliptic structures are fully determined by the Lagrangian subgroups of the discriminant group. As a consequence, we prove that for a large class of Picard rank 2 elliptic K3 surfaces all Fourier-Mukai partners are Jacobians, and we partially extend this result to non-closed fields. We also show that there exist elliptic K3 surfaces with Fourier-Mukai partners, which are not Jacobians of the original K3 surface. This gives a negative answer to a question raised by Hassett and Tschinkel.

DISTRIBUTION AND CHARACTERISTICS OF MESENTERIC MILK SPOTS IN HEALTHY RATS AND THOSE WITH ADHESION DISEASE

Introduction. The adhesion process occurs in more than 80% of cases after all abdominal operations. The process of adhesion formation and, as a consequence, chronic inflammation involve the lymphoid elements (Peyer's spots, solitary follicles) present in the peritoneum and submucosa of the intestine, causing a pathological immune response. Fat-associated lymphoid clusters (FALCs), known as mammary structures, are also found in other fat reservoirs, such as the pericardium, mediastinum, and pleural cavity. The problem of visualizing milk spots in various structures of the peritoneum remains open. Relevance. Despite the fact that as early as 1921, scientists emphasized the presence of milk spots in the abdominal cavity and their great biological significance, the results of experimental studies related to milk spots are still relatively few. The novelty consists in investigating the peculiarities of the distribution of milk spots in the mesentery of the intestine with adhesion disease in rats in comparison with the health animals.
 Objective of this study is to detect milk spots, to investigate their topography and structure in the mesentery of the intestine in the health and in adhesion disease.
 Materials and methods: The experiment involved tissue preparation, macroscopic examination, histological analysis of hematoxylin and eosin-stained film preparations.
 Results. Milk spots of the intestinal mesentery in rats from the intact group are represented by round formations, 1-2 μm in diameter, white in color, uniformly and diffusely located on the area of the mesentery of the small and large intestine. Microscopically, they are characterized as a cluster of lymphocytes, plasma cells, and macrophages belonging to FALC lymphoid tissue. The area of milk spots of the peritoneum in the experimental groups varies depending on the course of the process of adhesion formation. Individual small white and gray granulations were observed in the animals of the II experimental group on the 7th day. On the 14th day of observation in the III group, the diameter of the milk spots reached 2-2.5 mm, they appeared as white granular clusters. On the 21st day, the animals of the IV group demonstrated an abundant accumulation of elliptical whitish structures, 3-4 mm in diameter near the blood vessels that differed significantly from the indicators of the other groups.
 Conclusion. The study has expanded knowledge regarding the distribution and composition of milk spots in the normal mesentery compared to those observed in adhesion disease. According to data obtained, milk spots are lymphoid tissue, represented by various types of lymphocytes, macrophages and plasma cells. The question of whether the lymphocytes found in the milk spots belong to different subpopulations, the dynamics of their number during the main stages of adhesion formation, remains an open question requiring further scientific research.

Elliptical magnetic trajectories of a point on the elliptical 2-sphere

Elliptical trajectories play numerous significant roles in mathematics and physics. The focus of this work is to analyze the trajectories of a point on the ellipsoid S a 1 , a 2 , a 3 2 while it is under the influence of a killing vector field K. For this purpose, we introduce the generalized Darboux frame and the variational vector fields of S a 1 , a 2 , a 3 2 . We were able to get the trajectory equations of the charged particle on the ellipsoid by utilizing the elliptical structure and elliptic inner and cross product. We adopted a clearer and more comprehensible strategy in this way. With the aid of a mathematical program, we were able to display the paths we had determined based on the particle's velocity vector's position in the magnetic field. These trajectories are spiral, helical, and elliptical.

Explaining supernova remnant G352.7-0.1 as a peculiar type Ia supernova inside a planetary nebula

I identify a point-symmetric morphology of the supernova remnant (SNR) G352.7-0.1 and propose that the outer axially-symmetric structure is the remnant of a common envelope evolution (CEE) of the progenitor system, while the inner structure is the ejecta of a thermonuclear explosion triggered by the merger of a white dwarf (WD) and the core of an asymptotic giant branch (AGB) star. The main radio structure of SNR G352.7-0.1 forms an outer (large) ellipse. The bright X-ray emitting gas forms a smaller ellipse with a symmetry axis inclined to the symmetry axis of the large radio ellipse. The high abundance of iron and the energy of its X-ray lines suggest a type Ia supernova (SN Ia). The massive swept-up gas suggests a relatively massive progenitor system. I propose a scenario with progenitors of initial masses of MZAMS,1≃5–7M⊙ and MZAMS,2≃4–5M⊙. At a later phase, the WD remnant of the primary star and the AGB secondary star experience a CEE that ejects the circumstellar material that swept up more ISM to form the large elliptical radio structure. An explosion during the merger of the WD with the core of the AGB star triggered a super-Chandrasekhar thermonuclear explosion that formed the inner structure that is bright in X-ray. A tertiary star in the system caused the misalignment of the two symmetry axes. This study adds to the wide variety of evolutionary routes within the scenarios of normal and peculiar SNe Ia.

As small as they seem?

We present the results of an experimental study designed to investigate the acceptability of bare participial structures in spoken Italian. These sentences, despite being extremely reduced, have full illocutionary force. For the study, we proposed a technique to elicit grammaticality judgements suitable for structures that, although productive, are not used in the written form of the language. Our aim is to investigate the validity of the structural analysis of these sentences (Cecchetto & Donati 2022) according to which they are generated as small as VPs and they are not elliptical structures, i.e., they are not the result of phonological deletions from full-fledged sentences. The findings globally confirm the predictions of that account, as only require the activation of projections beyond the VP-layer, are rated as fully acceptable. However, the corresponding negative structures and some reduced structures with active transitive predicates received intermediate judgments of acceptability, contrary to the predictions. In the paper, we try to account for these unexpected results and argue that phonological deletion is available as well but is subject to tight constraints; most notably, it is restricted to the top of the tree.

Mechanical Properties and Microstructure of Inconel 718 Lattice Structures Produced by Selective Laser Melting Process.

This article presents the results of an analysis regarding the microstructure, mechanical strength, and microhardness of two kinds of samples built through selective laser melting with Inconel 718, the most frequently used alloy in metal additive manufacturing due to its excellent mechanical properties. The sample geometry was made up of two types of lattice structures with spherical and hyperbolical stiffness elements. The goals of these studies are to determine how homogenization heat treatment influences the microhardness and the mechanical properties of the specimens and to identify the structure with the best mechanical properties. The analysis showed that heat treatment was beneficial because the regular dendritic structure disappears, the δ phase precipitates at the grain boundaries, and both the γ and γ″ phases dissolve. It has also been shown that the structures with hyperbolical stiffness elements have better compressive strength than the structures with the elliptical structures, with a 47.6% increase for the as-fabricated structures and an approximate 50% increase for the heat-treated structure.

Back to heterotic strings on ALE spaces. Part II. Geometry of T-dual little strings

This work is the second of a series of papers devoted to revisiting the properties of Heterotic string compactifications on ALE spaces. In this project we study the geometric counterpart in F-theory of the T-dualities between Heterotic ALE instantonic Little String Theories (LSTs) extending and generalising previous results on the subject by Aspinwall and Morrison. Since the T-dualities arise from a circle reduction one can exploit the duality between F-theory and M-theory to explore a larger moduli space, where T-dualities are realised as inequivalent elliptic fibrations of the same geometry. As expected from the Heterotic/F-theory duality the elliptic F-theory Calabi-Yau we consider admit a nested elliptic K3 fibration structure. This is central for our construction: the K3 fibrations determine the flavor groups and their global forms, and are the key to identify various T-dualities. We remark that this method works also more generally for LSTs arising from non-geometric Heterotic backgrounds. We study a first example in detail: a particularly exotic class of LSTs which are built from extremal K3 surfaces that admit flavor groups with maximal rank 18. We find all models are related by a so-called T-hexality (i.e. a 6-fold family of T-dualities) which we predict from the inequivalent elliptic fibrations of the extremal K3.

Optical Spectroscopy and Photoionization Model of Planetary Nebula NGC 6572

We investigated NGC 6572 through optical spectroscopy to determine its kinematical and chemical properties. Two intermediate dispersion spectra (R~5000) centered around Hα and Hβ were used to derive the nebular expansion velocity from emission lines associated with Hα, Hβ, [OIII], [NII], and [SII] ions. A low dispersion spectrum (R~1000) was used to determine the nebular electron temperature, density, and chemical composition. We performed photoionization modeling to construct a self-consistent nebular model, whileintermediate-resolution spectral images showed the global elliptical structure of the nebula. The expansion velocity deduced from most of the emission lines is consistent with the typical expansion velocity of planetary nebulae, i.e., around 15-20 kms-1. The nebular physical properties align well with those determined by other studies. The nebular abundances were found to be lower than the solar abundances (except for oxygen) but still comparable with the abundances derived by other researchers. The photoionization model generated spectral lines that are consistent with the lines found in the observations. Further spectroscopic observations with higher resolution and wider range at various position angles will be very useful to reveal a more complete and detailed structure of the nebula and to improve the determination of the nebular physical properties.

Dynamic response of auxetic and functionally graded piezoelectric energy harvester using PVDF polymer

Piezoelectric energy harvesting has garnered greater interest in the past two decades than other vibration energy harvesting techniques for wireless power sensors and portable electronics. This work initially considers a bimorph cantilever with a solid substrate for analysis, keeping the first eigenfrequency below 100 Hz for environmental energy harvesting. Polyvinylidene fluoride (PVDF)-polymer is used as piezoelectric material due to its higher flexibility and brass is used as a substrate. The cantilever beam of length (L), width (B), the thickness of the substrate (t s) and piezoelectric layer (t p) are 50, 12.5, 0.14, and 0.25 mm, respectively, considered for analysis and having an eigenfrequency of 44 Hz. Further, an auxetic substrate (elliptical structure) and functionally graded piezoelectric material are incorporated to enhance power output. The maximum power is obtained as 8.33, 8.97 and 3.3 mW for conventional (solid) substrate, auxetic substrate and functionally graded piezoelectric layer under 3.5g excitation. The auxetic design has enhanced power output, whereas functionally graded materials have better surface bonding.

Analytical subthreshold swing model of junctionless elliptic gate-all-around (GAA) FET

<abstract> <p>An analytical subthreshold swing (SS) model has been presented to determine the SS of an elliptic junctionless gate-all-around field-effect transistor (GAA FET). The analysis of a GAA FET with an elliptic cross-section is essential because it is difficult to manufacture a GAA FET with an accurate circular cross-section during the process. The SS values obtained using the proposed SS model were compared with 2D simulation values and other papers to confirm good agreement. Using this analytical SS model, SS was analyzed according to the eccentricity of the elliptic cross-section structure. As a result, it was found that the carrier control ability within the channel improved as the eccentricity increased due to a decrease in the effective channel radius by a decrease in the minor axis length and a decrease in the minimum potential distribution within the channel, and thus the SS decreased. There was no significant change in SS until the eccentricity increased to 0.75 corresponding to the aspect ratio (AR), the ratio of the minor and major axis lengths, of 1.5. However, SS significantly decreased when the eccentricity increased to 0.87 corresponding to AR = 2. As a result of the SS analysis for changes in the device parameters of the GAA FET, changes in the channel length, radius, and oxide film thickness significantly affected the changing rate of SS with eccentricity.</p> </abstract>