Symmetrical Arrangement Research Articles

Observation of the perturbed eigenvalues of PT-symmetric LC resonator systems

We address both theoretically and experimentally the influence of asymmetric perturbation on the eigenvalues of parity-time (PT) symmetric resonator systems under the symmetric gain-loss arrangement, based on an inductively coupled inductor-capacitor-resistor (LCR) pair. The perturbed eigenvalues have been theoretically presented, numerically simulated, and experimentally measured. It shows that the asymmetric perturbation breaks PT-symmetry, leading to complex eigenvalues, which is different from the broken PT-symmetric phase with complex-conjugate eigenvalues. We have analyzed the perturbed frequency responses in all phases. At the exceptional points (EP), the resulting eigenvalues splitting is proportional to the square root of perturbation, showing the advantage of being highly sensitive to asymmetric perturbation. Meanwhile, the smaller the perturbation, the higher the sensitivity. The perturbation effect of PT-symmetric systems may be utilized to detect small signal changes in LC passive wireless sensors.

New perspective on chiral exceptional points with application to discrete photonics

Chiral exceptional points (CEPs) have been shown to emerge in traveling wave resonators via asymmetric back scattering from two or more nano-scatterers. Here, we provide a new perspective on the formation of CEPs based on the coupled oscillator model. Our approach provides an intuitive understanding for the modal coalescence that signals the emergence of CEPs and emphasizes the role played by dissipation throughout this process. In doing so, our model also unveils an otherwise unexplored connection between CEPs and other types of exceptional points associated with parity-time symmetric photonic arrangements. In addition, our model also explains qualitative results observed in recent experimental work involving CEPs. Importantly, the tight-binding nature of our approach allows us to extend the notion of CEP to discrete photonics setups that consist of coupled resonator and waveguide arrays, thus opening new avenues for exploring the exotic features of CEPs in conjunction with other interesting physical effects such as nonlinearities and topological protections.

Design, system modeling and energy management for a novel hydraulic pumping unit

Compared to conventional pumping units with low efficiencies and general hydraulic pumping units using hydraulic accumulators to recover and reuse energy, this article presents a novel multi-source hydraulic pumping unit with the symmetrical structure in order to save energy. First, the balanced mechanical structure through the symmetrical arrangement of double wells can not only decrease the total power of the system significantly but also make the power consumption of the pumping unit drop substantially in the constant speed phase. Uniquely, the proposed pumping unit is jointly driven by a hydrostatic transmission hydraulic system and a small-scale solar–wind hybrid power generation system. The hydrostatic transmission technique enables the system power output to adapt to the load requirements in real time without extra throttling and overflow losses, while the solar–wind hybrid system drives alone in the constant speed phase to save energy and bring environmental benefits. After parameter analyses and calculations, the energy-saving advantage of the proposed system is displayed when compared to a counterpart. Then, the mathematical model of the system is developed, and the rule-based energy management strategy is designed for the energy distribution of the proposed system. The simulation results verify that the feasibility and reasonableness of the proposed system.

Compact single‐varactor diode frequency‐reconfigurable microstrip patch antenna

A single-varactor frequency-reconfigurable microstrip patch antenna is presented. The antenna comprises a symmetrical arrangement of four metallised patches coupled and interconnected via slots and metallic bars, respectively. The antenna structure is excited through a single feed probe connected to one of the patches. To achieve a compact size of 22 × 21 × 1.57 mm, a shorting pin is placed close to the feed point to pull down the antenna's resonant frequency. By adding a varactor diode at the centre of the patch, frequency reconfigurability is introduced. Variation in the varactor's DC reverse bias voltage from 0 to 7.5 V results in a corresponding resonant frequency shift from 1000 to 1150 MHz, thus providing a tuning range of 15%. The proposed design is compact and achieves frequency reconfiguration with a single-varactor diode and a low bias voltage requirement compared with the design characteristics reported in existing works. The antenna can find application in various existing and emerging communication systems.

Evaluating Measure of Reformed Rotatability for Second Degree Polynomial Using a Pair of Incomplete Block Designs with Two Unequal Block Sizes

In this paper, a study on evaluating measure of reformed rotatability for second degree polynomial using a pair of incomplete block designs with two unequal block sizes (like symmetrical unequal block arrangements with two unequal block sizes) is suggested which enables us to assess the degree of reformed (modified) rotatability for a given response surface design.

Silicon Doping Effect on the Electronic Behavior of Graphene Nanoscrolls

The rising demand for developed electronics has led researchers to explore new design approaches using new materials and processes. The current device scaling using these new nanomaterials in advanced fabrication processes greatly improves the overall efficiency and performance of various electronic designs. In this study, the electronic behavior of all types of silicon-doped carbon nanoscrolls including armchair, zigzag, and chiral carbon nanoscrolls is investigated. Although the electronic properties of silicon carbide-based nanostructures and methods of synthesis have garnered great research attention in recent years, to date there have been no studies investigating analytical models or numerical simulation for the energy band structures and electronic characteristics of silicon carbide nanoscrolls. This paper presents a detailed analytical model of the energy band structure for various chiralities of silicon-doped graphene nanoscrolls and silicon carbide nanoscrolls. Our numerical results reveal metallic behavior for most small-diameter armchair Si-doped carbon nanoscrolls. However, for a given (n,n) armchair nanoscroll, the nanoscroll is a semiconductor if n is a multiple of 3. This is due to the effect of the quantization line intersection at the Dirac points. For larger diameters of armchair Si-doped carbon nanoscrolls, there is a small band gap between the associated valence and the conduction band which translates to semiconducting behavior.ae Our numerical study illustrates zero band gap for small-diameter zigzag silicon carbide nanoscrolls, which leads to metallic properties, while in larger nanoscrolls a small energy gap is seen. It seems that the associated energy gap is changed according to the overlap of the first spiral turn with the other turns. Also, the presence of variable small band gaps between the associated valence and conduction bands in large-diameter chiral nanoscrolls reveals that chiral Si-doped carbon nanoscrolls mainly exhibit semiconducting behavior. In the end, all the numerical results are tabulated as a periodic table in which a symmetric arrangement with respect to the armchair nanoscrolls is observed, and as a table diagonal data for the chiral Si-doped carbon nanoscrolls. Moreover, the effects of length variations on the energy structure of silicon carbide nanoscrolls is highlighted in the study.

Second Order Rotatable Designs of Second Type using Symmetrical Unequal Block Arrangements with Two Unequal Block Sizes

Second Order Rotatable Designs of Second Type using Symmetrical Unequal Block Arrangements with Two Unequal Block Sizes

Simple Carrier-Based PWM for Prolonged High DC-Link Utilization for Symmetrical and Asymmetrical $n$-Phase AC Drives

Square voltage waveforms enable high dc-link utilization (DLU) in multiphase ac drives. Circulating-current filters were devised to attenuate the harmonics in no-torque low-impedance subspaces. Nonetheless, the square-wave harmonics that generate torque ripple are not reduced. Recently, it was proposed to combine circulating-current filters with a carrier-based pulsewidth modulation (PWM) method, which injects harmonics in no-torque subspaces (attenuated by the filter) of five-phase motors to achieve high DLU, without harmonics associated with torque ripple. The filter allows prolonged high-DLU operation without overheating. Compared with other PWM techniques capable of high-DLU operation (overmodulation), the one proposed for said filters is especially convenient because of its simplicity. However, it is unclear if this PWM method can be extended to machines of any phase number n and winding arrangement (symmetrical or asymmetrical); and if so, the resulting performance is also unknown. This article extends this simple carrier-based PWM strategy to n-phase drives, and evaluates its behavior in terms of DLU, distortion, and computational burden. Symmetrical and asymmetrical winding arrangements are considered. The improvement in DLU, compared with conventional PWM with zero-sequence injection, is considerable. Current distortion is negligible with a suitable filter. The simplicity over other high-DLU PWM techniques is remarkable. Experimental results are provided.

Symmetrical arrangement of proteins under release-ready vesicles in presynaptic terminals

Controlled release of neurotransmitters stored in synaptic vesicles (SVs) is a fundamental process that is central to all information processing in the brain. This relies on tight coupling of the SV fusion to action potential-evoked presynaptic Ca2+ influx. This Ca2+-evoked release occurs from a readily releasable pool (RRP) of SVs docked to the plasma membrane (PM). The protein components involved in initial SV docking/tethering and the subsequent priming reactions which make the SV release ready are known. Yet, the supramolecular architecture and sequence of molecular events underlying SV release are unclear. Here, we use cryoelectron tomography analysis in cultured hippocampal neurons to delineate the arrangement of the exocytosis machinery under docked SVs. Under native conditions, we find that vesicles are initially "tethered" to the PM by a variable number of protein densities (∼10 to 20 nm long) with no discernible organization. In contrast, we observe exactly six protein masses, each likely consisting of a single SNAREpin with its bound Synaptotagmins and Complexin, arranged symmetrically connecting the "primed" vesicles to the PM. Our data indicate that the fusion machinery is likely organized into a highly cooperative framework during the priming process which enables rapid SV fusion and neurotransmitter release following Ca2+ influx.

Post‐Separation Parenting Time Schedules in Joint Physical Custody Arrangements

AbstractObjectiveThe objective of the study was to examine patterns of parenting time schedules in joint physical custody (JPC) arrangements.BackgroundAlthough the importance of contact with the non‐residential parent for children's well‐being after family dissolution is well‐documented, the measures used in surveys are often crude and do not capture the two dimensions of post‐separation parenting time schedules: the proportion of time children spend with each parent and the number of transitions children make between parental homes.MethodThe analyses are based on the Family Models in Germany study, a German sample of families with children aged 0–14 that was conducted in 2019. As this study includes a residential calendar capturing the children's stays with each parent over 4 weeks, it was possible to calculate both dimensions of post‐separation parenting time schedules for 463 JPC families.ResultsThe results revealed that 55.5% of JPC families practiced an asymmetric (at least 30% with one parent) and 44.5% practiced a symmetric care arrangement (50% with each parent). The mean number of transitions children experienced was 9.5 within a month. The factors that were found to be positively associated with practicing symmetric JPC were working hours of the responding parent and parents' relationship quality. However, working hours of the responding parent and the distance between the parents' homes reduced the number of transitions between the parents' homes, whereas a good parental relationship increased them.ConclusionEmpirical investigations of children in post‐separation families should take the two dimensions of physical custody into account.

Simulation and Analysis of glare effect of two lane tunnel lighting under symmetrical lighting arrangement

Glare seriously affects the quality of tunnel lighting, and also has a negative impact on drivers’ visual recognition in the tunnel. By introducing the calculation method of glare influence level G and relative threshold increment TI, the article uses DIAlux evo lighting simulation analysis software to simulate and analyze the tunnel lighting glare of different installation spacing and angle combinations under the condition of Symmetrical lighting on both sides in the tunnel. The influence range of glare produced by different installation spacing and angle combinations under symmetrical lighting is obtained. The research results show that: in the symmetrical lighting mode on both sides of the tunnel, when the angle between the driver’s sight line and the incident direction of the tunnel lighting is less than 82.38°, the lamps will produce glare to the driver. When the glare influence level of symmetrical bat-wing tunnel lamp is between 1 and 3 at any installation distance and angle under the symmetrical arrangement of lights on both sides, it is a serious glare effect.

Bandgap evolution in nanographene assemblies.

Recently cycloarene has been experimentally obtained in a self-assembled structure, forming graphene-like monoatomic layered systems. Here, we established bandgap engineering/prediction in cycloarene assemblies within a combination of density functional theory and tight-binding Hamiltonians. Our results show that the inter-molecule bond density rules the bandgap. The increase in such bond density increases the valence/conduction bandwidth decreasing the energy gap linearly. We derived an effective model that allows the interpretation of the arising energy gap for general particle-hole symmetric molecular arrangements based on inter-molecular bond strength.

A STRUCTURALIST ANALYSIS OF WILLIAM SHAKESPEARE’S “ROMEO AND JULIET

Structuralism is an approach that defines the relationship between the part and the whole. This study aims to analyse William Shakespeare’s “Romeo and Juliet” in terms of the structuralist approach. In the surface structure, there is love between Romeo Montague and Juliet Capulet who are the children of hostile families. In terms of syntagmatic relation, Romeo and Juliet fall in love with each other, decide to marry and keep it in secret. In terms of paradigmatic relation, there is homology of relationship between the two hostile families. As for the surface structure, there is a symmetrical arrangement of plot between public scenes and private scenes. As for the surface meaning, there is the thematic conflict between hatred and love. As for the deep structure, its harmony operates on binary opposition between public hatred and private love. Its melody operates on the fixed cycle of public hatred and private love. As for the deep meaning, where there is public hatred, private love is helpless. Love can live forever only when society is in peace.

Crystal Structure Algorithm (CryStAl): A Metaheuristic Optimization Method

Metaheuristics are computational procedures that intelligently lead the search process through the efficient exploration of the search space associated with an optimization problem. With the progressive outburst of problems with large data sets in various fields, there is an ongoing quest for enhancing existing metaheuristic algorithms as well as developing new ones with greater accuracy and efficiency. In general, a powerful and efficient metaheuristic algorithm is based on a rich inspiration source, implemented effectively through a precise mathematical model. Aiming to develop a highly efficient, nature-inspired optimization algorithm, here we propose a novel metaheuristic called Crystal Structure Algorithm (CryStAl). This method is chiefly inspired by the principles underlying the formation of crystal structures from the addition of the basis to the lattice points, which is a natural phenomenon that can be seen in the symmetric arrangement of constituents (i.e. atoms, molecules, or ions) in crystalline minerals such as quartz. A total number of 239 mathematical functions which are categorized into four different groups are utilized to evaluate the overall performance of the proposed method. To validate the results of this novel algorithm, 12 different classical and modern metaheuristic algorithms are selected from the literature. The minimum, mean, and standard deviation values alongside the number of function evaluations for CryStAl and the other metaheuristics for a specific tolerance are calculated and presented accordingly. The obtained results, further supported by a complete statistical analysis, demonstrated that the proposed algorithm is capable of providing very competitive results, outperforming the other metaheuristics in most cases.

Structure Design of Cable-Stayed Bridge Intelligent Detection Robot

Cables are the main load-bearing components of cable-stayed Bridges. The durability and reliability of cables are directly related to the safe operation and service life of the whole bridge. Aiming at the problem of cable detection and maintenance, a new type of cable detection robot is designed in this paper. To further enhance the stability of the robot, the structure adopts symmetrical arrangement to make the center of mass of the robot system coincide with the cable axis. According to the working condition of the robot, a flexible body spring that meets the parameter requirements is designed, which not only meets the required preload, but also meets the starting torque of the motor. The robot is simple in structure, standardized in parts, easy to assemble and disassemble, and has good obstacle clearance ability and detection efficiency.

On Second Order Slope Rotatable Designs under Intra-class Correlated Structure of Errors Using a Pair of Dissimilar Incomplete Block Designs

In this paper, a study of second order slope rotatable designs under intra-class correlation error structure using two suitably chosen dissimilar incomplete block designs like balanced incomplete block designs and symmetrical unequal block arrangements with two unequal block sizes are suggested. Further, we study the variance of the estimated slopes for different values of the intra-class correlation coefficient (ρ) and the distance from the centre (d) for v factors are suggested. Some illustrative examples are also suggested.

An Orthogonal Mechanical Model of Stable Nuclei

The following article presents a mechanical model approach for stable atomic nuclei based on a symmetrical orthogonal arrangement of protons and neutrons. This rigid approach lends support to nuclear pairing, shell modeling (without gaps), and symmetry concepts of nuclear structure and does not support independent particle models where nucleons move in mean free paths within the nucleus. The disparity between the number of stable nuclides with an even number of protons and those with an odd number of protons is examined and then used to postulate possible orthogonal mechanical models of nuclei. The ability to predict subsequent abundant nuclei based on the pattern developed for the first twenty or so nuclides gives credence to the proposed model. To further validate this pattern, an electron orbiting arrangement about the orthogonal axes is developed which adapts the pattern to the periodic table. Each vertical column in the periodic table makes up a related group of elements based on their chemical behavior. This article will show how electron orbiting patterns on two axes group elements in accordance to the Periodic Table and opens the door for pushing physics beyond the standard mode (BSM). In the interest of simplicity, binding energies and energy levels using quantum and wave mechanics are not described in this article.

Dielectric-Supported Staggered Dual Meander-Line Slow Wave Structure for an E-Band TWT

In this article, a novel dielectric-supported staggered dual-meander-line (DS-SDML) planar slow-wave structure (SWS) is proposed for a traveling wave tube (TWT) working at E-band. The proposed staggered arrangement of meander-lines (MLs) leads to a stronger beam-wave interaction and achieves higher output power as compared to the symmetric arrangement. The input-output couplers have been designed by using staggered stepped double ridge waveguide, to connect the standard E-band rectangular waveguide and the DS-SDML SWS. An attenuator and pitch tapering have been applied to the proposed SWS to suppress the unwanted frequencies and to improve the output power. Particle-in-cell (PIC) simulation results show that for an 11.8-kV, 200-mA sheet-beam, the output power can reach 283 W at 75 GHz, with a maximum gain and electronic efficiency of 34.5 dB and 11.9%, respectively.

Geometry and topology of symmetric point arrangements

We investigate point arrangements vi∈Rd,i∈{1,...,n} with certain prescribed symmetries. The arrangement space of v is the column span of the matrix in which the vi are the rows. We characterize properties of v in terms of the arrangement space, e.g. we characterize whether an arrangement possesses certain symmetries or whether it can be continuously deformed into another arrangement while preserving symmetry in the process. We show that whether a symmetric arrangement can be continuously deformed into its mirror image depends non-trivially on several factors, e.g. the decomposition of its representation into irreducible constituents, and whether we are in even or odd dimensions.

Extended properties of magnetic spins of zinc ferrite nanoparticles in the THz frequency range

We fabricated nanoparticles of Zn ferrite of the chemical formula ZnFe2O4 using the auto-combustion technique, and investigated their magnetic spin distribution and frequency response to optical excitation. Optical absorption and magnetic characterization of the nanoparticles were carried out in the UV–Vis and IR range, and extended on the low frequency side down to the THz domain. The nanoparticles were also characterized by X-ray diffraction and by magnetic force microscopy. The optical dielectric constant was calculated in both the UV–Vis and the THz domain. The optical bandgap, the dispersion energy and the oscillator strength of the nanoparticles were calculated from the optical data based on the single oscillator model. We measured the optical absorption, transmission and reflection spectra in the wavelength range from 200 to 800 nm, and calculated the refractive index, absorption and extinction coefficient. The optical band gap was found to be 1.14 eV and the oscillating energy of the dipole was determined to be 6.94 eV. The study shows that the coordination number of a metal complex and the symmetrical arrangement play an important role in determining the nanoparticle properties.