Ring Elements Research Articles

Metasurface with high cross-polarization isolation using rectangular split rings for simultaneous amplitude and phase controls

Metasurfaces have demonstrated significant potential for versatile modulation of electromagnetic waves. To enhance the control of electromagnetic waves, simultaneous control of amplitudes and phases is often essential in certain applications. The C-shaped split ring (SR) with polarization conversion and its deformed structures can fulfill this requirement; however, such structures encounter the challenge of low polarization isolation, which is mainly reflected in its inherent characteristics of low polarization isolation and the deterioration of polarization isolation in amplitude control. In this paper, a reflective metasurface with improved polarization isolation is proposed. The designed metasurface consists of rectangular split ring (R-SR) elements, which can realize both amplitude and phase controls simultaneously and independently while exhibiting higher polarization isolation than the conventional SR element. Furthermore, an alternating mirror rotation method (AMRM) for the arrangement of amplitude-control elements is proposed to suppress the degradation of polarization isolation caused by amplitude control. Several metasurfaces are designed to verify the characteristics of the proposed R-SR structure and the effectiveness of the AMRM. Finally, two reflective metasurfaces composed of R-SR elements and SR elements with identical configurations are designed and manufactured. Both the simulation and measured results demonstrate the versatility of the proposed design and its advantages in terms of polarization isolation and transfer efficiency.

Broadband self-isolating MIMO antenna array for 6G IoT systems

A novel antenna array with improved radiation characteristics using a series-feed technique is presented in this article. The antenna array has a size of 132 × 80 μm and is developed using Polytetrafluoroethylene (PTFE) with graphene as conductive material. The proposed antenna comprises a central microstrip line loaded with short slant radiating stubs. The bandwidth characteristics of the antenna are enhanced by loading the slant stubs with octagonal ring elements. The number of radiating stubs is increased to enhance the overall radiation characteristics. The proposed THz antenna operates from 3.8 THz to 5.3 THz offering a fractional bandwidth of 31 % with reference |S11| ≤ −10 dB. In addition, a 1 × 2 antenna array with differential feeding is explored to improve the overall directionality of the antenna making it a viable solution for directional IoT systems. The estimated theoretical directivity is above 11 dBi and the total efficiency is greater than 75 % throughout the operating bandwidth. Furthermore, the multiple input and multiple output (MIMO) performance of the THz antenna is discussed. The proposed two-element has an intrinsic isolation of more than 40 dB. Owing to the enhanced bandwidth and radiation property, the proposed THz antenna is suitable for high data-rate 6 G Internet-of-things (IoT) communications.

Secondary teachers’ guided reinvention of the definitions of reducible and irreducible elements

Informed by Realistic Mathematics Education, we designed a hypothetical learning trajectory on graduate students’ guided reinvention of reducible and irreducible elements in rings. We created experientially real context problems for use in a teaching experiment, in which secondary in-service and pre-service teachers used algebra tiles as an emergent model of factoring integers and quadratics in Zx. In their mathematical activity, this became the teachers’ model for abstracting the shared structure of (ir)reducible elements in Z and Z[x], which they used to formally define (ir)reducible elements. In this paper, we discuss the progression of the teachers’ reasoning and defining activities that were evident as they reinvented the definitions of reducible and irreducible elements of integral domains.

One-sided EP elements in rings with involution

One-sided EP elements in rings with involution

The Tribological Properties of Novel Sulfoximine Derivatives as Lubricant Additives.

Introducing an additive is a practical approach to improve the lubrication performance of base oil in the field of tribology. Herein, a series of sulfoximine derivatives was synthesized and incorporated into base oil A51 as additives. The tribological properties of these lubricants were evaluated at both room and high temperatures, and the result demonstrated that they displayed excellent friction reduction and wear resistance in the friction process under both test conditions. Moreover, the chemical composition of the worn scar surface was inspected using EDS, XPS and TOF-SIMS to explore the lubricating mechanism. It is reasonable to conclude that the synergistic interaction between the aromatic ring scaffolds and elements like N, F, and S facilitated the adsorption of lubricant on the steel block surfaces and forming a tribofilm during the friction process. This tribofilm has a dominant impact on the system's lubrication performance. This research provides novel oil-soluble lubricant additives, offering a facile approach to formulating high-quality lubricants.

(w,v)-core–EP inverse and (w,v)-pseudo-core inverse

The core and core–EP inverses are two recent generalized inverses that were first introduced and studied for complex matrices, and later for elements of rings with involution. Afterward, weighted versions (the w-core–EP inverse and the weighted w-core inverse with weight v) were introduced. Our purpose is to study all these generalized inverses in the context of monoids with involution, in a unified way. With this in mind, we introduce new, broader kinds of generalized inverses. In particular, we present the ( w , v ) -core–EP inverse and the ( w , v ) -pseudo-core inverse for elements of a monoid with involution. Necessary and sufficient conditions for the existence of these inverses are proved, and some representations of these new inverses are developed. Using these results, we obtain new properties of the weighted w-core inverse with weight v. We finally consider these inverses in the matrix setting. We notably prove that these inverses provide minimum norm or least square solutions to some matrix equations.

A remark on the paper of Deninger and Murre

We show that the results proven by Deninger and Murre in their paper (Deninger and Murre, 1991) directly imply that the Chern classes of the de Rham bundle of an abelian scheme are torsion elements in the Chow ring, a result that was later proven by van der Geer. We also discuss several results about the orders of these classes.

Integration of ecological indicators to assess a multitemporal impact of cement industries

The present study evaluated an integrated biomonitoring approach based on three different bioindicators: tree rings, lichens, and beetles in a complex environment (urban-industrial-forest). In Central Italy, four sampling sites were selected to assess the anthropogenic impact of cement plants taking into account (1) long-term exposure (1988–2020) through the analysis of trace elements in tree rings of Quercus pubescens; (2) medium-term exposure (2020–2021) through the analysis of trace elements in thalli (outermost portions) of the lichen Xanthoria parietina; (3) short-term exposure in spring 2021 through the bioaccumulation and evaluation of sample vitality in transplants of the lichen Evernia prunastri and a periodic survey of entomological biodiversity carried out during spring and summer 2021. Trace elements of industrial origin were found in tree rings, with different levels of accumulation between 1988 and 2020 and a maximum in 2012. Native thalli of the lichen X. parietina showed an overall low bioaccumulation of trace elements except for Cr, probably reflecting the influence of national lockdown measures. The transplants of E. prunastri showed a weak stress response in the industrial and urban sites, but not in the forest, and identified Tl and V as the main elements contributing to atmospheric contamination, with peaks at the industrial sites. Concerning the beetles, a significantly lower number of species was found at the Semonte industrial site.

Modern views on the pathogenesis of intervertebral disc degeneration

Introduction. Intervertebral disc (IVD) degeneration is defined as a multifactorial degenerative disease of the spine, starting from the structures of the nucleus pulposus of the IVD, spreading to the fibrous ring and other elements of the spinal motion segment. Unlike natural aging, a pathological degenerative process that occurs in IVDs as a result of the additive effect of genetic predisposition and external environmental factors leads to the formation of chronic back pain and reduces the patient’s quality of life. Despite many years of studying the problem of the pathogenesis of IVD degeneration, it is far from being resolved, which encourages us to further study the pathogenetic mechanisms of the development of this pathology.Aim. To update the knowledge of practicing neurologists about the results of modern studies of the leading mechanisms of development of IVD degeneration in humans and their role in the development of promising biomarkers of this pathology and new strategies for pathogenetic therapy.Materials and methods. A search and analysis of publications was carried out in Russian-language (e-Library) and Englishlanguage databases (PubMed, Oxford Press, Clinical Keys, Springer, Elsevier, Google Scholar). Search depth – 5 years (2018–2023).Results. The analyzed and generalized results of studies of the molecular mechanisms influencing the development and progression of this pathology are presented. The leading pathogenetic mechanisms for the development of IVD degeneration, such as oxidative stress and the NO system, cytokine imbalance, increased activity of matrix metalloproteinases, dysfunction of fibrillar collagens and proteoglycan, as well as their relationship with each other, were considered.Conclusion. The review provides a broader look at the pathogenetic mechanisms of IVD degeneration, which makes it possible to set new goals for future development of promising therapeutic strategies.

A broadband single‐layer reflectarray antenna with split ring element

AbstractA broadband single‐layer reflectarray comprising three‐layer concentric split ring elements is proposed. The reflection phase is achieved by changing the flare angle of the inner and outer split rings. The resonance of the element is easily controlled by varying the relative relationships between the homomorphic patches. And the length of the split ring changes in the azimuth direction, which improves the utilization rate of unit space. The middle split ring acts as a parasitic structure with constant size, making the surface current distribution of the element more uniform to improve the element bandwidth. A reflectarray containing 256 elements is designed and tested. The measured results indicate that the peak gain is 25.3 dBi corresponding to the aperture efficiency of 42%. And the 1‐dB gain bandwidth of the reflectarray of 21.7% is achieved.

Mesoscopic ring element growth and deformation induced biofilm streamer evolution in microfluidic channels.

In a fluid environment, biofilms usually form and grow into streamers attached to solid surfaces. Existing research on single streamers studied their formation and failure modes. In the experiment on biofilm growth in a microfluidic channel, we found that rings composed of bacteria and an extracellular matrix are important elements on a mesoscopic scale. In the fluid environment, the failure of these ring elements causes damage to streamers. We simulated the growth and deformation of the ring structure in the micro-channel using multi-agent simulation and fluid-structure coupling of a porous elastic body. Based on this, we simulated the biofilm evolution involving multi-ring deformation, which provides a new length scale to study the biofilm streamer dynamics in fluid environments.

On pro-zero homomorphisms and sequences in local (co-)homology

Let x_ denote a system of elements of a commutative ring R. For an R-module M we investigate when x_ is M-pro-regular resp. M-weakly pro-regular as generalizations of M-regular sequences. This is done in terms of Čech co-homology resp. homology, defined by Hi(Cˇx_⊗R⋅) resp. by Hi(RHomR(Cˇx_,⋅))≅Hi(HomR(Lx_,⋅)), where Cˇx_ denotes the Čech complex and Lx_ is a bounded free resolution of it as constructed in [17] resp. [16]. The property of x_ being M-pro-regular resp. M-weakly pro-regular follows by the vanishing of certain Čech co-homology resp. homology modules, which is related to completions. This extends previously work by Greenlees and May (see [5]) and Lipman et al. (see [1]). This contributes to a further understanding of Čech (co-)homology in the non-Noetherian case. As a technical tool we use one of Emmanouil's results (see [4]) about the inverse limits and its derived functor. As an application we prove a global variant of the results with an application to prisms in the sense of Bhatt and Scholze (see [3]).

Annihilators and decompositions of singularity categories

Abstract Given any commutative Noetherian ring R and an element x in R, we consider the full subcategory $\mathsf{C}(x)$ of its singularity category consisting of objects for which the morphism that is given by the multiplication by x is zero. Our main observation is that we can establish a relation between $\mathsf{C}(x), \mathsf{C}(y)$ and $\mathsf{C}(xy)$ for any two ring elements x and y. Utilizing this observation, we obtain a decomposition of the singularity category and consequently an upper bound on the dimension of the singularity category.

Ring elements of stable range one

A ring element a∈R is said to be of right stable range one if, for any t∈R, aR+tR=R implies that a+tb is a unit in R for some b∈R. Similarly, a∈R is said to be of left stable range one if Ra+Rt=R implies that a+b′t is a unit in R for some b′∈R. In the last two decades, it has often been speculated that these two notions are actually the same for any a∈R. In §3 of this paper, we will prove that this is indeed the case. The key to the proof of this new symmetry result is a certain “Super Jacobson's Lemma”, which generalizes Jacobson's classical lemma stating that, for any a,b∈R, 1−ab is a unit in R iff so is 1−ba. Our proof for the symmetry result above has led to a new generalization of a classical determinantal identity of Sylvester, which will be published separately in [45]. In §§4-5, a detailed study is offered for stable range one ring elements that are unit-regular or nilpotent, while §6 examines the behavior of stable range one elements via their classical Peirce decompositions. The paper ends with a more concrete §7 on integral matrices of stable range one, followed by a final §8 with a few open questions.

SAFE PERFORMANCE OF WORKS IN CONSTRUCTION AND HOUSING AND COMMUNAL SERVICES USING THE ORIGINAL SCAFFOLDING DESIGN

Our development relates to construction, namely scaffolding and scaffolding used when working at height. It is intended for fencing the work area when carrying out various types of work, for example, when performing brickwork from scaffolding. In construction, where safety and efficiency play a crucial role, the correct selection and use of scaffolding are integral to every successful project. We have proposed a patent-protected solution. It is a scaffolding railing consisting of vertical support posts hinged with horizontal crossbars, characterised by the fact that each support post is made in the form of a telescopic connection of pipes of different diameters with the possibility of extending them from each other and is fixed with the help of an existing locking device. The hinge connection of horizontal crossbars with them, except the upper row of such bars that are railing, is made in random order, for example, by attaching a hinge to the upper end of the upper tube of the smallest diameter, and is carried out using additional ring elements mounted on the corresponding telescopic connecting tubes. The inner diameter of each of these annular elements, exceeding the outer diameter of the tube on which it is mounted, is less than the outer diameter of the next subordinate telescopic tube. Thus, it can move only vertically in a telescopic connection within this and above pipes. It makes it possible to support each of the ring elements with horizontal crossbars attached to them under their weight at a certain level of height of the vertical support post, determined by the height of the underlying tube of the telescopic connection. At the same time, the lower horizontal crossbar is hinged to the ring element of the largest diameter, put on the lower tube of the telescopic connection, and rested directly on the working flooring made in the form of a sideboard. The proposed device is not technically complex to implement. Its use increases the workers’ productivity, improves the working conditions, and ensures the safety of various construction works. Keywords: safety, construction, ease of use, prototype, fencing, scaffolding.

Investigation on the influence of temperature-variation clearance on the frequency of rolling bearing defects

The clearance between the inner ring (IR) of rolling bearing and rotor is directly proportional to the temperature rise. The increased friction between the IR and rotor, as well as changes in the frequency of rolling bearing defects, and the accuracy of bearing health monitoring decreases. Existing research cannot effectively solve this problem. In response to the above issues, in this paper, the clearance between the bearing IR and the rotor and the internal clearance of bearing were considered, and the clearance was considered as the motion boundary of the rotor inside the IR, dynamic models of the bearing IR, outer ring (OR), and rolling element defects were established, and the trend of rolling bearing defects frequencies with temperature was analyzed, then the rationality of the dynamic models were verified through experimental methods. The research results show that the friction between the rotor and the IR increases with increasing temperature, and the speed of the IR decreases accordingly. The characteristic frequencies of defects in the IR, OR, and rolling element of rolling bearings have decreased by approximately 6.42%, 8.07%, and 6.93% compared to the theoretical values without considering temperature, respectively. This indicates that when identifying the frequency of rolling bearing defects at different temperatures, the frequency deviation caused by the increase in clearance between the IR and the rotor should be considered. The research results may serve as an important basis for fault diagnosis and condition monitoring of rolling bearings.

Idempotent and nilpotent elements in octonion rings over Z

In this paper, we show that the set O/Zp, where p is a prime number, does not form a skew field and discuss idempotent and nilpotent elements in the (finite) ring O/Zp. We provide examples and establish conditions for idempotency and nilpotency. Mathematics Subject Classification (2010): 15A33, 15A30, 20H25, 15A03. Received 27 July 2021; Accepted 14 December 2021

On permutation polynomials modulo 7n

A polynomial that permutes the elements of a finite ring R is known as a permutation polynomial. The conditions for the coefficients of a polynomial of degree d to be a permutation polynomial modulo pn, are known for p = 2, 3, 5. In this paper, we obtain the necessary and sufficient conditions on the coefficients of a polynomial modulo 7n to be a permutation polynomial.

Self-similar ring element array develop for Fano response as mid-infrared: Liver cancer study

the mid-infrared metasurfaces play an important in optical applications including sensing and having Fano response is a benefit in this field for many goals including biosensing. So, these points are considered in this study and self-similar Plasmonic metasurface is suggested for sensing application. The suggested structure has a symmetrical formation but non-similar elements are considered to raise the Fano response. The structure contains five rings while the central one has a larger dimension than the four elements surrounding the central ring as an array of rings. The interaction of bright modes for both elements of the central ring and the array elements makes the Fano response at 1850 and 1910 nm while the single central ring has resonance at 1910 nm and the array rings have resonance at 1850 nm. The interaction of the element enhances the Q-factor of both resonances. The Full-wave method finite integrated technique (FIT) is used for modeling as a time domain method and the couple mother theory (CMT) is used for the analytical model. This metasurface is implemented as a sensor for detecting material under test and the sensitivity of the sensor is obtained 282 nm/RIU (Refractive Index Unit). Finally, the tissue of the liver as healthy and cancer cells are considered for examining the quality of the sensor.

An application of a virus optimization algorithm to the problem of computing binary self-dual and LCD codes

In this paper, we employ a virus optimization (VO) algorithm, which is one of the metaheuristic optimization techniques, and a known construction method to compute many new binary $ [72,36,12] $ self-dual codes and optimal/near-optimal linear complementary dual (LCD) codes. In particular, we obtain 39 Type Ⅰ and 19 Type Ⅱ codes of length 72, with parameters in their weight enumerators that were not known in the literature before, and 85 new binary LCD codes that are either optimal or near-optimal. We also present the generator matrix of extended Golay code $ [24,12,8] $ by a cyclic group matrix ring element.