Ring Model Research Articles

Novel Magnetic Field Modeling Method for a Low-Speed, High-Torque External-Rotor Permanent-Magnet Synchronous Motor

In view of the unstable electromagnetic performance of the air gap magnetic field caused by the torque ripple and harmonic interference of a multi-slot and multi-pole low-speed, high-torque permanent magnet synchronous motor, we propose a simplified model of double-layer permanent magnets. The model is divided into an upper and a lower subdomain, with the upper subdomain being an ideal circular ring and the lower subdomain being a segmented sector ring. Moreover, we develop an exact analytical model of the motor that predicts the magnetic field distribution based on Laplace’s and Poisson’s equations, which is solved using the method of separating variables. Taking a 40p168s low-speed, high-torque permanent magnet synchronous motor as an example, the accuracy of the model is verified by comparison with an ideal circular ring model, a segmented sector ring model, and the finite element method. Based on the proposed simplified model, three combined permanent magnets considering both edge-cutting and polar arc cutting structures are proposed, which are chamfered, rounded, and rectangular combinations. Under the premise of a consistent edge-cutting amount, the electromagnetic characteristics of the three combination types of permanent magnets are compared using the finite element method. The results show that the electromagnetic characteristics of the chamfered combination PM are superior to those of the other two combinations. Finally, a prototype is manufactured and tested to validate the theoretical analysis.

Computing primitive idempotents in finite commutative rings and applications

In this paper, we compute an algebraic decomposition of black-box rings in the generic ring model. More precisely, we explicitly decompose a black-box ring as a direct product of a nilpotent black-box ring and unital local black-box rings, by computing all its primitive idempotents. The algorithm presented in this paper uses quantum subroutines for the computation of the p-power parts of a black-box ring and then classical algorithms for the computation of the corresponding primitive idempotents. As a by-product, we get that the reduction of a black-box ring is also a black-box ring. The first application of this decomposition is an extension of the work of Maurer and Raub (2007) on representation problem in black-box finite fields to the case of reduced p-power black-box rings. Another important application is an IND-CCA1 attack for any ring homomorphic encryption scheme in the generic ring model. Moreover, when the plaintext space is a finite reduced black-box ring, we present a plaintext-recovery attack based on representation problem in black-box prime fields. In particular, if the ciphertext space has smooth characteristic, the plaintext-recovery attack is effectively computable in the generic ring model.

Numerical Studies on the Motions of Magnetically Tagged Cells Driven by a Micromagnetic Matrix.

Precisely controlling magnetically tagged cells in a complex environment is crucial to constructing a magneto-microfluidic platform. We propose a two-dimensional model for capturing magnetic beads from non-magnetic fluids under a micromagnetic matrix. A qualitative description of the relationship between the capture trajectory and the micromagnetic matrix with an alternating polarity configuration was obtained by computing the force curve of the magnetic particles. Three stages comprise the capture process: the first, where motion is a parabolic fall in weak fields; the second, where the motion becomes unpredictable due to the competition between gravity and magnetic force; and the third, where the micromagnetic matrix finally captures cells. Since it is not always obvious how many particles are adhered to the surface, attachment density is utilized to illustrate how the quantity of particles influences the capture path. The longitudinal magnetic load is calculated to measure the acquisition efficiency. The optimal adhesion density is 13%, and the maximum adhesion density is 18%. It has been demonstrated that a magnetic ring model with 100% adhesion density can impede the capture process. The results offer a theoretical foundation for enhancing the effectiveness of rare cell capture in practical applications.

Theory of nonequilibrium asymptotic state thermodynamics: Interacting Ehrenfest urn ring as an example.

A generalized class of the nonequilibrium state, called the nonequilibrium asymptotic state (NEAS), is proposed. The NEAS is constructed within the framework of Fokker-Planck equationsin thermodynamic limit. Besides the usual equilibrium state and nonequilibrium steady state (NESS), the class of NEAS could also cover the nonequilibrium periodic state (NEPS) in which its dynamics shows periodicity, the nonequilibrium quasiperiodic state (NEQPS), and nonequilibrium chaotic state (NECS) in which its dynamics becomes chaotic. Based on the theory of NEAS thermodynamics, the corresponding thermodynamics of different NEASs could also be determined. Finally the interacting Ehrenfest urn ring model is used as an example to illustrate how different kinds of NEAS (equilibrium state, uniform NESS, nonuniform NESS, NEPS) in the three-urn case are identified in our framework. In particular, the thermodynamics of NEPS and its phase transitions to other types of NEAS are studied.

New Ring Models of Atoms and Molecules

New Ring Models of Atoms and Molecules

Response retention and apparent motion effect in visual cortex models.

Apparent motion is a visual illusion in which stationary stimuli, flashing in distinct spatial locations at certain time intervals, are perceived as one stimulus moving between these locations. In the primary visual cortex, apparent-motion stimuli produce smooth spatio-temporal patterns of activity similar to those produced by continuously moving stimuli. An important prerequisite for producing such activity patterns is prolongation of responses to brief stimuli. Indeed, a brief stimulus can evoke in the visual cortex a long response, outlasting the stimulus by hundreds of milliseconds. Here we use firing-rate based models with simple ring structure, and biologically-detailed conductance-based refractory density (CBRD) model with retinotopic space representation to analyze the response retention and the origin of smooth profiles of activity in response to apparent-motion stimuli. We show that the strength of recurrent connectivity is the major factor that endorses neuronal networks with the ability for response retention. The same strengths of recurrent connections mediate the appearance of bump attractor in the ring models. Factors such as synaptic depression, NMDA receptor mediated currents, and conductances regulating spike adaptation influence response retention, but cannot substitute for the weakness of recurrent connections to reproduce response retention in models with weak connectivity. However, the weakness of lateral recurrent connections can be compensated by layering: in multi-layer models even with weaker connections the activity retains due to its feedforward propagation from layer to layer. Using CBRD model with retinotopic space representation we further show that smooth spatio-temporal profiles of activity in response to apparent-motion stimuli are produced in the models expressing response retention, but not in the models that fail to produce response retention. Together, these results demonstrate a link between response retention and the ability of neuronal networks to generate spatio-temporal patterns of activity, which are compatible with perception of apparent motion.

ANALISIS FUNGSI KORELASI KLASIK DAN KUANTUM UNTUK MODEL CINCIN: SEBUAH REVIEW

A review of the journal entitled 'Classical And Quantum Correlation Functions For A Ring Model' has been carried out which discusses the solutions of classical and quantum correlation functions for the ring model. Classical and quantum correlation functions are derived for systems of non-interacting particles moving in a circle. demonstrated that the decay behavior of the classical expression for the correlation function can be recovered from a strictly periodic quantum mechanical expression by taking the limit ℏ→0, after the appropriate transformation. The aim of this study is to present clearly and in detail how the position correlation function for a system of particles moving in a circle having a certain average energy and written in a form which shows the nature of the transformation. Next, we examine the use of Poisson addition to represent F(z), and how the correlation function becomes identical to the form given by classical statistical mechanics, which exhibits Gaussian decay. The results of this study indicate that the positional correlation function for a system of particles moving in a circle, and having a certain average energy, can be written in a form which shows the nature of the transformation. Then using the Poisson addition formula to represent F(z), the expression is rewritten to enable the limit ℏ→0 to be taken. It was finally found that the correlation function became identical to the form given by classical statistical mechanics, which exhibits a Gaussian decay.

Finite element 3D model of a double quantum ring: effects of electric and laser fields on the interband transition

In this work, the changes in the energy of electrons and holes, oscillator strength and interband transition time when external fields are applied to a GaAs/AlGaAs semiconductor double ring grown by the droplet epitaxy technique are theoretically analyzed. We consider a static electric field and an intense laser field nonresonant with the quantum structure, with variable intensities and orientations with respect to the symmetry axis of the quantum ring (QR). In the formalism of the effective mass approximation for electrons and holes, the energies and wavefunctions were numerically computed using the finite element method implemented with an accurate three-dimensional model of the real QR. Laser dressing of the confining potential was performed using the exact integration formula at each point. Our results show major differences between the effects of the two types of applied fields, caused mainly by the static electric-field-induced strong polarizability of the confined electron-hole pair. In addition, the effects of both fields exhibit strong anisotropy in the electronic properties as a result of the particular flattened geometry of the QR. Proper combinations of field strengths and orientations are helpful in designing accurate tools for the sensitive manipulation of interband radiative properties.

Optimization of rolling bearing dynamic model based on improved golden jackal optimization algorithm and sensitive feature fusion

Some simplified modeling parameters in the traditional rolling bearing dynamics model led to poor consistency between the simulated and measured vibration signals. In addition, the simulated signal has low accuracy, which in turn reduces the accuracy of bearing fault diagnosis based on the simulated signal. Thus, to resolve the above-mentioned issues, this study presents a method for optimizing rolling bearing dynamics models based on an improved golden jackal optimization (IGJO) algorithm and sensitive feature fusion. Firstly, this study proposes an IGJO algorithm using a dimension-by-dimension reverse learning strategy and adaptive weights to address the interplay of dimensions in the multidimensional optimization process and the imbalance between the global and local search abilities of the GJO. Secondly, a fusion strategy for bearing fault-sensitive features is proposed based on the binary's improved golden jackal optimization (B-IGJO) algorithm and principal component analysis (PCA). In this strategy, the Sigmoid function discretization method is used to obtain the B-IGJO algorithm, which is then applied to the measured signal to select the bearing fault sensitivity features. These features are analyzed using PCA to obtain the fused sensitivity feature expression. Finally, the fusion-feature expressions are used to calculate the fusion-sensitive features of the measured and simulated vibration signals, and then the residuals of the two are used as the objective function for model optimization. The parameters of the rolling bearing dynamics model are updated using the IGJO. The proposed method is experimentally verified through a single pitting fault dynamics model of the outer ring of the rolling bearing. In conclusion, our results confirm the effectiveness and feasibility of the proposed method.

An improved lumped parameter model of the single free-flooded ring transducer using Helmholtz–Kirchhoff integral solution

The Helmholtz-Kirchhoff integral (HKI) may be considered as the boundary element method (BEM) used to calculate the acoustic pressure at any position in the 3D-radiation problem from a vibrating surface. This method provides valuable insights into the radiation characteristics of vibrating structures, which may offer significant information and tools to underwater transducer design engineers during the early stages of development. It may save considerable computational costs in the design processes for the underwater transducer such as Hull Mount Sonar. This study illustrates usefulness of the HKI-based approach by developing a simple model of the Free Flooded Ring (FFR) transducer using a piezoelectric ring model and the HKI solution on the surface acoustic pressure of the ring through their physical conditions on their connected interfaces. The FFR transducer is widely utilized as a low-frequency acoustic source in underwater environments due to its broad operating frequency bandwidth and relatively small size. The developed approach aims to construct a precise model that considers the sound-structure interactions between the piezoelectric ring and the acoustic medium around it. To validate the accuracy of the proposed method, the acoustic pressure and electrical admittance are compared with those obtained through finite element method (FEM) simulations.

Diabatic quantum annealing for the frustrated ring model

Quantum annealing (QA) is a continuous-time heuristic quantum algorithm for solving or approximately solving classical optimization problems. The algorithm uses a schedule to interpolate between a driver Hamiltonian with an easy-to-prepare ground state and a problem Hamiltonian whose ground state encodes solutions to an optimization problem. The standard implementation relies on the evolution being adiabatic: keeping the system in the instantaneous ground state with high probability and requiring a time scale inversely related to the minimum energy gap between the instantaneous ground and excited states. However, adiabatic evolution can lead to evolution times that scale exponentially with the system size, even for computationally simple problems. Here, we study whether non-adiabatic evolutions with optimized annealing schedules can bypass this exponential slowdown for one such class of problems called the frustrated ring model. For sufficiently optimized annealing schedules and system sizes of up to 39 qubits, we provide numerical evidence that we can avoid the exponential slowdown. Our work highlights the potential of highly-controllable QA to circumvent bottlenecks associated with the standard implementation of QA.

COMPUTATIONAL MODELING OF A LAYERED AORTIC MEDIAL WALL CONSIDERING EFFECTIVE RESIDUAL STRESSES

We previously developed a simplified finite element (FE) “unit” model to reproduce the mechanical interaction between the smooth muscle layer and elastic lamina (EL) in the aortic media. Nevertheless, whether this simplified FE model can represent the structure of a real medial wall and whether its modeling technique can help in developing a highly sophisticated and structure-based aortic FE model should be determined. Therefore, this study aimed to computationally represent EL buckling in the aortic medial ring at an unloaded state based on the integrated unit models and reproduce transmural variations in EL waviness across the vascular wall. We confirmed that the inner and outer layers of the medial wall were relatively subjected to compressive and tensile residual stresses, respectively, at the unloaded state, implying that the ring model will open spontaneously when it is radially cut. In addition, the residual stresses computed under such a stress-free condition were comparable to the analytically estimated values, partially supporting the validity of our modeling approach. Although further study is still required, the information obtained in this study will greatly improve the understanding of basic aortic physiology and pathophysiology and provide a basis for performing more sophisticated computational modeling of the aortic wall.

Computational Modeling of an Aortic Medial Wall: Effect of Residual Stresses on a Mechanical Behavior of the Aortic Ring

Abstract The aorta is the largest artery in an animal body and is an important organ in the pulsatile flow regulation from the left ventricle. The mechanical and structural characteristics of the aortic media, which are primarily composed of smooth muscle cell layers and elastic laminae (ELs), have profound effects on the physiology and pathophysiology of the aorta. However, many aspects of the aortic tissue remain unknown due to the inherent layered wall structure and the regionally varying residual stresses. This study aimed to computationally represent EL buckling in the aortic medial ring at the unloaded state and reproduce the transmural variation in residual stresses and EL waviness across the vascular wall. A multi-objective optimization technique was applied to a series of simulations with the “unit” structure to obtain an idealized stress distribution throughout the aortic wall thickness. Hence, an appropriate boundary condition given to an initial reference configuration of the aortic ring was successfully identified. As a result, the average “idealized” residual stresses of smooth muscle cell layer and EL were on the order of 20 and −80 kPa, respectively, while EL waviness was ∼1.01 in the unloaded state. Further, it was verified that the ring model with a radial cut will open spontaneously when the inner and outer layers of the medial wall are subjected to relative compressive and tensile residual stresses, respectively, in the unloaded state.

Thermoelastic dissipation of circular-cross-sectional ring including nonlocal and dual-phase-lagging effects

In the high-frequency region, thermoelastic damping (TED) is essential to ensure the accuracy of micro- or nano-precision sensors or actuators. The size-effect of molecules should be considered in the design and analysis since the atomic volume is not negligible in the nanoscale model. Moreover, a toroidal ring is easy to manufacture, so there is a high possibility that it will be developed in the near future. And thus, the 3-dimensional (3D) TED model of a circular cross-sectional ring is investigated by adopting dual-phase-lagging (DPL) and modified couple stress (MCS) theories based on nonlocal elasticity. Additionally, the size-dependent influences are specified by length-scale parameters in the elastic and thermal fields. Then the TED results are predicted as a quality factor (Q) with the peaks of the spectra and are compared separately by the causes of physical quantity. Moreover, the phenomenon is analyzed in terms of how the properties and length-scale parameters correlate with each other. Finally, it is confirmed that nonlocal elasticity should be considered when the size of the resonator decreases to the scale of the energy-carrying mean-free path. In this regard, this work provides an idea for the analysis of DPL TED of the toroidal ring, including nanoscale effects based on nonlocal elasticity and MCS theories.

Multicopper Clusters Enable Oxidative Phenol Macrocyclization (OxPM) of Peptides.

The biosynthesis of glycopeptide antibiotics such as vancomycin and other biologically active biaryl-bridged and diaryl ether-linked macrocyclic peptides includes key enzymatic oxidative phenol macrocyclization(s) of linear precursors. However, a simple and step-economical biomimetic version of this transformation remains underdeveloped. Here, we report highly efficient conditions for preparing biaryl-bridged and diaryl ether-linked macrocyclic peptides based on multicopper(II) clusters. The selective syntheses of ring models of vancomycin and the arylomycin cyclic core illustrate the potential of this technology to facilitate the assembly of complex antibiotic macrocyclic peptides, whose syntheses are considered highly challenging. The unprecedented ability of multicopper(II) clusters to chelate tethered diphenols and promote intramolecular over intermolecular coupling reactions demonstrates that copper clusters can catalyze redox transformations that cannot be accessed by smaller metal catalysts.

The EB Correlation in Resolved Polarized Images: Connections to the Astrophysics of Black Holes

We present an in-depth analysis of the newly proposed correlation function in visibility space, between the E and B modes of linear polarization, hereafter the EB correlation, for a set of time-averaged general relativistic magnetohydrodynamical simulations compared with the phase map from different semianalytic models and the Event Horizon Telescope (EHT) 2017 data for M87*. We demonstrate that the phase map of time-averaged EB correlation contains novel information that might be linked to black hole (BH) spin, accretion state, and electron temperature. A detailed comparison with a semianalytic approach with different azimuthal expansion modes shows that to recover the morphology of real/imaginary part of the correlation function and its phase, we require higher orders of azimuthal modes. To extract the phase features, we use Zernike polynomial reconstruction developing an empirical metric to break degeneracies between models with different BH spins that are qualitatively similar. We use a set of geometrical ring models with various magnetic and velocity field morphologies, showing that both the image space and visibility-based EB-correlation morphologies in magnetically arrested disk simulations can be explained with simple fluid and magnetic field geometries as used in ring models. Standard and normal evolutions by contrast are harder to model, demonstrating that the simple fluid and magnetic field geometries of ring models are not sufficient to describe them owing to higher Faraday rotation depths. A qualitative comparison with the EHT data demonstrates that some of the features in the phase of EB correlation might be well explained by the current models for BH spins and electron temperatures, while others require larger theoretical surveys.

Laboratory study on mechanical behavior of hollow π-type steel–concrete composite support in loess tunnel

Failure or over-deformation of tunnel supports is common when tunneling in loess areas. Steel-concrete composite support (SCCS) is an innovative new support system that could provide a viable solution to improve the support in loess tunnels. Due to a lack of research, there is only a preliminary understanding of the structural effects of employing π-type SCCS arch as the initial load-bearing element. Based on similarity theory, we perform a large-scale ring model test to investigate the mechanical behavior of the π-type SCCS arch without grouting under typical surrounding loess pressure, i.e., symmetric and asymmetric bias pressure distributions. The damage patterns, deformation evolution, and structural strain development are obtained via the experimental investigation and presented in detail. The progressive failure and ultimate bearing capacity of the hollow π-type SCCS arch are further compared under a designed loading situation. It is concluded that the failure of the π-type SCCS arch has three stages, including the coordinate deformation stage, the load-bearing stage, and the failure stage, respectively. However, the deformation and failure modes under different surrounding pressure behave differently. The stiffness and bearing capacity of the π-type SCCS arch under symmetrical pressure is 1.65 and 1.16 times greater than that under asymmetric pressure, respectively. This experimental study provides new insights into the mechanical behavior of new arch frames for loess tunnel construction, which can serve as a benchmark for further theoretical and numerical studies.

Theoretical predictions and electronic properties of thiolate-protected gold nanocluster: Au44(SR)32

Thiolate-protected gold nanoclusters have received extensive attention both experimentally and theoretically due to their excellent physical and chemical properties. However, comprehending the geometric structure of thiolate-protected gold nanoclusters remains a challenging task. Predicting the structural configuration of these ligand-protected gold nanoclusters can enhance our understanding of this class of materials. Due to the current lack of knowledge regarding the structure of Au44(SR)32, we employed the grand unified model (GUM) for gold core stacking and the ring model to describe interfacial interactions between gold cores and the protection motifs. Based on these models, we successfully predicted the geometric structure of Au44(SR)32 clusters and demonstrated partial reproducibility between the calculated absorption spectra and experimental results. Furthermore, by analyzing the energy levels and molecular orbitals, we have identified that the absorption spectra of Au44(SR)32 arise from d→d and d→sp transitions, with the low-energy state primarily resulting from Au44-to-core transitions and the high-energy state from Au44-to-ligand transitions. These findings not only enhance our understanding of Au44(SR)32 clusters but also validate the effectiveness and applicability of GUM and ring model in predicting stable structures of thiolate-protected gold nanoclusters.

Lubrication analysis of the piston ring for the two-stroke marine diesel engine based on modified radial tension

As the piston ring is inserted into the bore, it is forced against the liner by radial tension, thereby creating a seal. Radial tension not only affects the piston ring’s seal, but also significantly influences its tribological properties. To investigate the effect of non-uniform radial tension of piston ring on the lubrication properties, a contact finite element model of piston ring and cylinder liner tribo-pairs is constructed in this study. The contact pressure distribution between the tribo-pairs is determined based on this model. The obtained pressure is then regarded as the non-uniform radial tension of the ring, which is fitted to a formula. The formula is validated in two ways. Firstly, its generality is verified by simulating several different piston rings using the contact model and comparing their results with the formula. Second, a test rig was designed and set up to measure the piston ring’s circumferential tension. To verify the formula’s accuracy, an equivalent principle model of distributed pressure and concentrated force was proposed. This formula is used as an initial force to modify the piston ring mixed lubrication model. Based on this model, the lubrication performance of the piston ring with uniform radial tension and non-uniform radial tension into consideration is investigated. The findings demonstrate that the piston ring radial tension is of significance to its lubrication performance and can be modified to lessen local friction and wear issues, particularly those related to the piston ring gap, and thus improve the dependability of the piston ring.

Adopting a new approach for finding missing people using GIS techniques: A case study in Saudi Arabia’s desert area

Abstract Every year, hundreds of people go missing in the wilderness of Saudi Arabia. There is an urgent need to examine modern geographic techniques for finding such people. Geographical information systems, for example, play a crucial role in wilderness search and rescue (WiSAR), not only in mapping probability areas but also in applying further analysis and modeling methods to reduce time and effort and to guide life-saving task forces in the right direction. In this study of a hypothetical missing-person case in Saudi Arabia, two standard WiSAR models are compared: ring and mobility. In the presented study situation, both models can be used. However, the new approach used in the mobility model drastically reduces the extent of the possible search area, from 101,787 km2 in the ring model to 335.34 km of likely trails and unpaved roads, and also provides exact directions to where the missing person may be found.