Bracket Structure Research Articles

Unique 3D metamaterial split ring resonator for wireless communication with high negative refractive index and for medium ratio

This article presents the unique 3D metamaterial split ring resonator (3D-MTM SRR) model with high negative refractive index and effective medium ratio at 2.45 GHz frequency. It is integrated with two layers: one square bracket structure printed on the back side of the substrate and another dual split ring with an air gap placed above the substrate. Both structures are coupled by metallic vias, which serve as connecting vias to create the 3D-MTM SRR model. Simulation and experiment results shows good agreement for high negative refractive index and effective medium ratio of −17 and 6.16, respectively. To fully comprehend the resonance phenomena of the proposed 3D-MTM model, an analogous circuit analysis is carried out. In addition, to validate the MTM activities, array topologies based on 3D-MTM cells are analyzed. Thus the unique properties of 3D-MTM SRR allow to develop the high-performance RF devices for wireless applications.

Design of negative refractive index 3D metamaterial split ring resonator for IoT applications

AbstractThis article presents the unique 3D metamaterial split ring resonator (3D‐MTM SRR) with a high negative refractive index at 2.45 GHz frequency. It is integrated with two layers: one square bracket structure printed on the backside of the substrate and another dual split ring with an air gap placed above the substrate. Both structures are coupled with metallic vias, which serve as connecting vias to create the 3D‐MTM SRR. Simulation and experiment results show good agreement for a high negative refractive index and the effective medium ratio of −30 and 6.16, respectively. To fully comprehend the resonance phenomena of the proposed 3D‐MTM, an analogous circuit analysis is carried out. Thus, the unique properties of 3D‐MTM SRR allow development of the high‐performance radio frequency devices for IoT applications.

Hamiltonian Particle-in-Cell methods for Vlasov–Poisson equations

In this paper, Particle-in-Cell algorithms for the Vlasov–Poisson system are presented based on its Poisson bracket structure. The Poisson equation is solved by finite element methods, in which the appropriate finite element spaces are taken to guarantee that the semi-discretized system possesses a well defined discrete Poisson bracket structure. Then, splitting methods are applied to the semi-discretized system by decomposing the Hamiltonian function. The resulting discretizations are proved to be Poisson bracket preserving. Moreover, the conservative quantities of the system are also well preserved. In numerical experiments, we use the presented numerical methods to simulate various physical phenomena. Due to the huge computational effort of the practical computations, we employ the strategy of parallel computing. The numerical results verify the efficiency of the new derived numerical discretizations.

Lightweight Design of Shock-Absorbing and Load-Bearing Components Based on 3D Printing Technology

Nowadays, the redesign of new shock-absorbing load-bearing parts has gradually gained more and more focus due to the pressure of energy, environmental protection, and people’s pursuit of high-performance (light weight, excellent shock absorption, etc.) travel tools, and the development of 3D printing technology provides the possibility to design such high-performance parts. Therefore, firstly, the strength analysis of the parts is carried out by adopting Altar Inspire software, then topology optimization design is conducted in Inspire software and, finally, direct manufacturing is carried out using Aurora 3D printers. The results show that the maximum Mises equivalent stress of the shock-absorbing load-bearing components after lightweight design is not more than the material’s yield stress of 45 MPa and the safety factor (1.5) is greater than the minimum allowable safety factor (1.2); under such kind of premise, the quality is lightened by 63.82%. Moreover, since the structure of the parts becomes a bracket structure after the lightweight design, the shock absorption performance will be greatly improved. The 3D-printed parts have a series of advantages, namely bright surface, low roughness, no obvious warpage and other defects, and good molding effect, which lays solid the foundation for the mass production of high-performance shock-absorbing load-bearing parts.

Noncommutativity and Nonassociativity of Type II Superstring with Coordinate Dependent RR Field

AbstractIn this paper we will consider noncommutativity that arises from bosonic T‐dualization of type II superstring in presence of Ramond‐Ramond (RR) field, which linearly depends on the bosonic coordinates . The derivative of the RR field is infinitesimal. We will employ generalized Buscher procedure that can be applied to cases that have coordinate dependent background fields. Bosonic part of newly obtained T‐dual theory is non‐local. It is defined in non‐geometric space spanned by Lagrange multipliers . We will apply generalized Buscher procedure once more on T‐dual theory and prove that original theory can be salvaged. Finally, we will use T‐dual transformation laws along with Poisson brackets of original theory to derive Poisson bracket structure of T‐dual theory and nonassociativity relation. Noncommutativity parameter depends on the supercoordinates , and , while nonassociativity parameter is a constant tensor containing infinitesimal .

Efficient Reliability Analysis of Structures Using Symbiotic Organisms Search-Based Active Learning Support Vector Machine

Reliability-based design optimization considers the uncertainties that lie in the designing process of resilient buildings and structures. To model uncertainty, the major challenge is to lower the high computational expense incurred by the double-loop approach, where the design optimization (outer loop) repeatedly calls the reliability analysis of each structural design (inner loop). An alternative is to convert the reliability constraints to deterministic constraints by using optimality conditions. Yet, the approximated results are often inaccurate when constraint functions are highly non-linear, non-continuous, or non-differentiable. To achieve better accuracy while attaining sufficient flexibility, the present study proposes a new framework to classify the structural designs into feasible/infeasible designs. The proposed framework is called SOS-ASVM by integrating the symbiotic organism search (SOS) and the active-learning support vector machine (ASVM). ASVM is adopted as the surrogate model, while SOS is used to seek more representative samples to improve the classification accuracy of ASVM. The SOS-ASVM was validated by comparisons with popular classification tools: conventional support vector machine, artificial neural network, and Kriging model. Three practical engineering cases are used to demonstrate the performance of the SOS-ASVM: a cantilever beam, a bracket structure, and a 25-bar space truss. The comparison results confirm the superiority of the proposed framework to other tools.

Tectonics characterization of the salt influenced structures: Insights from a seismic data interpretation in the eastern part of the Persian Gulf, Iran

Salt tectonics can influence the petroleum systems via the development and distribution of ductile migration pathways through the structural and stratigraphic traps. In this study, the effects of base-salt relief on the development of salt décollement horizon and the salt-influenced structures were investigated in the eastern part of the Persian Gulf, NE of the Afro-Arabian Plate. For this purpose, data from hydrocarbon exploration wells and seismic lines of the region have been used. To set the position in a time of the main stratigraphic and acoustic markers, and to compare well and seismic data, the processing of synthetic seismogram and the conversion of logs in the time domain has been performed for the selected well.Interpretation of seismic sections revealed the occurrence of a NE-SW trending horst structure and development of a natural model of the salt tectonics on its overburden of the Oligocene to Miocene sedimentary layers. The presence of Oligo-Miocene saliferous beds as a décollement has provided suitable conditions for overburden sediments gravitational sliding and development of thin-skinned extension which started during the Miocene time and it was evolved up to the present time. This condition controlled the geometry of salt-influenced structures in the eastern parts of the Persian Gulf and resulted in the formation of special structural features namely hereafter as Curly Bracket Structures in the overburden.

Microstructure of unsaturated loess and its influence on strength characteristics

Previous studies have shown that structure has a significant influence on the mechanical deformation of unsaturated loess, but there is little published information focused on the influence mechanism of microstructure and mesostructure on the mechanical properties of loess. In this paper, the unsaturated undisturbed loess and its remolded loess under the same physical condition were taken as the research objects. The unsaturated triaxial shear tests with constant suction and net confining pressure were carried out, and the microstructure differences between the two are compared by using SEM and CT scanning to reveal the influence of structure on strength characteristics. The test results show that the cohesion and internal friction angle of undisturbed loess are greater than those of remolded loess. The angle of undisturbed soil particles is obvious, and the particles are bracket contact with good cementation. The remolded loess particles are close to round shape, and the particles are inlaid contact with destroyed cementation. The average radius of undisturbed soil is higher than that of remolded soil, indicating that there are bracket pores in undisturbed soil, but the bracket structure and macropores are deformed during shear deformation, and good structural and cementation ensure the strength of loess specimens.

Conserved laws and dynamical structure of axions coupled to photons

In this work, we carry out a study of the conserved quantities and dynamical structure of the four-dimensional modified axion electrodynamics theory described by the axion-photon coupling. In the first part of the analysis, we employ the covariant phase space method to construct the conserved currents and to derive the Noether charges associated with the gauge symmetry of the theory. We further derive the improved energy–momentum tensor using the Belinfante–Rosenfeld procedure, which leads us to the expressions for the energy, momentum, and energy flux densities. Thereafter, with the help of Faddeev–Jackiw’s Hamiltonian reduction formalism, we obtain the relevant fundamental brackets structure for the dynamic variables and the functional measure for determining the quantum transition amplitude. We also confirm that modified axion electrodynamics has three physical degrees of freedom per space point. Moreover, using this symplectic framework, we yield the gauge transformations and the structure of the constraints directly from the zero-modes of the corresponding pre-symplectic matrix.

Inevitability of the Poisson Bracket Structure of the Relativistic Constraints

The purpose of this paper is to shed some fresh light on the long-standing conceptual question of the origin of the well-known Poisson bracket structure of the constraints that govern the canonical dynamics of generally relativistic field theories, i.e. geometrodynamics. This structure has long been known to be the same for a wide class of fields that inhabit the space-time, namely those with non-differential coupling to gravity. It has also been noticed that an identical bracket structure can be derived independently of any dynamical theory, by purely geometrical considerations in Lorentzian geometry. Here we attempt to provide the missing link between the dynamics and geometry, which we understand to be the reason for this structure to be of the specific kind. We achieve this by a careful analysis of the geometrodynamical approach, which allows us to derive the structure in question and understand it as a consistency requirement for any such theory. In order to stay close to the classical literature on the subject we stick to the metric formulation of general relativity, but the reasoning should carry over to any other formulation as long as the non-metricity tensor vanishes. The discussion section is devoted to derive some interesting consequences of the presented result in the context of reconstructing the Arnowitt–Deser–Misner (ADM) framework, thus providing a precise sense to the inevitability of the Einstein’s theory under minimal assumptions.

Light absorption by interacting atomic gas in quantum optical regime.

Quantum optical theory of absorption properties of interacting atoms is developed. The concept of local absorptance is introduced as a derivative of the logarithm of intensity with respect to the distance in the vicinity of a given spatial point and a moment of time. The intensity is represented by the quantum and statistically averaged normal product of creation and annihilation operators of the electromagnetic field. The development of an analytical method of the estimation for the kinetic and optical parameters for the system is proposed here. The calculation method of the absorption coefficient includes thermal atomic motion, Doppler effect, and the short-range interaction between atoms. The absorption coefficient explicitly takes into account the quantum nature of the optical field. The ability of the system to absorb or emit quanta is quantitatively expressed through the special form of interaction integrals. The specific form of integrals results from the structure of the quantum brackets. The interplay between the collective (virtual photon exchange) and binary (optically induced inter-particle bonding) processes determines the system behavior. The spectral profile of the local absorption coefficient for different atomic densities and time intervals is simulated for realistic parameters.

Bimetric universe with matter

We analyze the early stage of evolution of a universe with two scale factors proposed in [1] when matter is present. The scale factors describe two causally disconnected patches of the universe interacting trough a non-trivial Poisson bracket structure in the momentum sector characterized by one parameter \kappa. We studied two scenarios in which one of the patches is always filled with relativistic matter while the other contains relativistic matter in one case, and non-relativistic matter in the second case. By solving numerically the set of equations governing the dynamics, we found that the energy content of one sector drains to the other and from here it is possible to constraint the deformation parameter \kappa by imposing that the decay of the energy density happens, at most, at the Big Bang Nucleosynthesis temperature in order to return to the usual behavior of radiation. The relation with Non Standard Cosmologies is also addressed.

Study on Dynamic Amplification Factor of UHV Pillar Equipment

In the research of UHV pillar equipment, the dynamic amplification factor of bracket is a key parameter. This paper mainly focuses on the relationship between the dynamic amplification factor of ceramic equipment under the condition of seismic acceleration response spectrum when the structural parameters of the bracket are the same. In this paper, the stiffness of the bracket is changed by altering the elastic modulus of the steel. The dynamic amplification factors of the speed, displacement, stress and acceleration of the bracket in the two kinds of overall structures are compared and analyzed by numerical simulation. At the same time, the relationship between the bracket frequency and the steel consumption is compared by calculating the steel consumption of different bracket structures. Based on the results of simulation analysis and considering the seismic design of porcelain electrical equipment in UHV substations and converter stations, it is suggested that the dynamic amplification factor, the envelope of displacement and stress amplification factor of 1.40 should be adopted, thus providing a theoretical basis for the design of UHV bracket equipment.

Mathrm{T}overline{mathrm{T}} -deformed nonlinear Schr\xf6dinger

The mathrm{T}overline{mathrm{T}} -deformed classical Lagrangian of a 2D Lorentz invariant theory can be derived from the original one, perturbed only at first order by the bare mathrm{T}overline{mathrm{T}} composite field, through a field-dependent change of coordinates. Considering, as an example, the nonlinear Schrödinger (NLS) model with generic potential, we apply this idea to non-relativistic models. The form of the deformed Lagrangian contains a square-root and is similar but different from that for relativistic bosons. We study the deformed bright, grey and Peregrine’s soliton solutions. Contrary to naive expectations, the mathrm{T}overline{mathrm{T}} -perturbation of nonlinear Schrödinger NLS with quartic potential does not trivially emerge from a standard non-relativistic limit of the deformed sinh-Gordon field theory. The c → ∞ outcome corresponds to a different type of irrelevant deformation. We derive the corresponding Poisson bracket structure, the equations of motion and discuss various interesting aspects of this alternative type of perturbation, including links with the recent literature.

A Rule-Based System to Promote Design for Manufacturing and Assembly in the Development of Welded Structure: Method and Tool Proposition

Welding is a consolidated technology used to manufacture/assemble large products and structures. Currently, welding design issues are tackled downstream of the 3D modeling, lacking concurrent development of design and manufacturing engineering activities. This study aims to define a method to formalize welding knowledge that can be reused as a base for the development of an engineering design platform, applying design for assembly method to assure product manufacturability and welding operations (design for welding (DFW)). The method of ontology (rule-based system) is used to translate tacit knowledge into explicit knowledge, while geometrical feature recognition with parametric modeling is adopted to couple geometrical information with the identification of welding issues. Results show how, within the design phase, manufacturing issues related to the welding operations can be identified and fixed. Two metal structures (a jack adapter of a heavy-duty prop and a lateral frame of a bracket structure) fabricated with arc welding processes were used as case studies and the following benefits were highlighted: (i) anticipation of welding issues related to the product geometry and (ii) reduction of effort and time required for the design review. In conclusion, this research moves forward toward the direction of concurrent engineering, closing the gap between design and manufacturing.

Finite element analysis of belt conveyor bracket

As an important part of the belt conveyor, the triangle bracket supports the roller and carries its load. Its stability and service life directly affect the function of the conveyor, so that the conveyor system can work stably and efficiently. Due to the characteristics of the belt conveyor, such as long transportation distance and large conveying volume, there are many problems in the actual working condition of the triangle. For example, the triangle bracket bears too much load, resulting in deformation and damage of the bracket structure. Working time is too long, the yield limit of the support is reduced, and the structure of the support is seriously failed, which leads to the shutdown of the conveying system and huge economic loss of the enterprise. There are many problems in the actual production of triangle bracket, so it is necessary to analyze and study triangle bracket to solve these problems. This project takes the triangle support of a belt conveyor as an example, establishes a three-dimensional solid model of the support, conducts finite element analysis on the triangle support model with ABAQUS software, analyzes the stress-strain displacement of the triangle support under the load, and optimizes the triangle support according to the finite element analysis results.

Fatigue life of the welding seam of a tracked vehicle body structure evaluated using the structural stress method

The supporting roller is an important component in the driving systems of tracked vehicles. Through the bracket structure, the supporting roller is bolted to the vehicle body welded with a reinforced metal plate, providing vertical support and lateral guidance of the track. The strengthening weld structure between the bottom plate and the vehicle body is the root of the cantilever beam, where stress is concentrated and fatigue damage is easily accumulated. The fatigue life of the whole vehicle is affected by the fatigue damage in this part. This paper proposes a structural stress method to evaluate the fatigue life of the welding seam of a tracked vehicle body. Further, the proposed method is evaluated under typical road-load spectra. Initially, the base-metal and weld structures were subjected to monotonic tensile and cyclic plastic deformation tests. The tensile strength of the weld sample was approximately half of that of the base metal. Next, the welded structure of the supporting roller bracket was simulated using a finite element model. The calculated stresses were consistent with the fatigue crack locations in the welded structure. The structural stress was not dependent on the grid density. Subsequently, multibody dynamic simulations of the whole tracked vehicle were performed on four standard road surfaces constructed using the harmony superposition method. The road-load spectra at the axle head of the supporting roller were calculated under four pavement conditions, and the fatigue life of the weld structure of the supporting roller bracket was determined. The calculated fatigue life was considerably lower than the designed fatigue life. Finally, the initial weld structure was redesigned by increasing the size of the strengthening metal plate and the weld length. The fatigue life of the redesigned structure was considerably longer than that of the original structure, indicating that the proposed method can effectively analyze the fatigue life of the welding seam and that it can be used to optimize the design scheme.

Effect of mounting bracket structure and material on automotive air conditioning compressor

ABSTRACT This paper proposes an analysis of Mounting Bracket Structure and Material effects on fixed-displacement swash-plate-type compressor. To decrease the interior sound pressure of a vehicle, both finite-element analysis (FEA) and vibration experiment of the automotive air conditioning compressor with the mounting bracket were conducted, and the effect of the material and structure of the mounting bracket on the noise and vibration of the compressor was analysed. The finite-element model of the fixed-displacement swash-plate-type compressor with a mounting bracket is established. For the mounting bracket with different materials and structures, vibration acceleration level (VAL) of the finite-element model was analysed. Results show that the mounting bracket MB3, which is made of QT400-10, provides the best noise and vibration performance, which is also verified through interior sound pressure level experiment. Abbreviations: FEA: finite-element analysis; VAL: vibration acceleration level; FRA: frequency response analysis; EMA: experimental modal analysis; LTI: Linear Time-Invariant; FEM: finite-element model; AMS: automatic multi-level substructuring; DOF: degree of freedom

Topological Lightweight Optimization Simulation on EMU Luggage Rack Bracket

Basing on unite simulation method with INSPIRE and HYPERMESH, topological lightweight optimization on coach luggage rack bracket structure of China Standard EMU train had been executed. By comparing the simulation results with the test data, accuracy of the computational models had been verified. It was proved that the modified luggage rack bracket structure would have better mechanical performance and reach the goal of lightweight at the same time.

Single and double generator bracket formulations of multicomponent fluids with irreversible processes

The equations of reversible (inviscid, adiabatic) fluid dynamics have a well-known variational formulation based on Hamilton’s principle and the Lagrangian, to which is associated a Hamiltonian formulation that involves a Poisson bracket structure. However, real flows also include irreversible processes, such as viscous dissipation, heat conduction, diffusion and phase changes. Recent work has demonstrated that the variational formulation can be systematically extended to include irreversible processes and nonequilibrium thermodynamics, through the new concept of thermodynamic displacement. Irreversible processes have also been incorporated into the bracket structure through the addition of a dissipation bracket. This gives what are known as the single and double generator bracket formulations, which are the natural generalizations of the Hamiltonian formulation to include irreversible dynamics. Unlike the variational formalism, most of these bracket formalisms do not follow from a systematic construction and have often been derived via a case by case approach, with slightly different axioms used in different situations. In this paper, we show that the variational formulation yields a constructive and systematic way to derive from a unified perspective these bracket formulations for fully compressible, multicomponent, multiphase fluids with a single temperature and velocity. In the case of a linear relation between the thermodynamic fluxes and the thermodynamic forces, the metriplectic or GENERIC brackets are recovered. Many previous results in the literature, typically obtained via heuristic approaches, are demonstrated to be special cases of this general formulation.