Dimensional Coupling Research Articles

Three Dimensional Scapulothoracic rhythm coupling in healthy subjects: comparison between dominant and non-dominant shoulders during unilateral flexion and abduction

Three Dimensional Scapulothoracic rhythm coupling in healthy subjects: comparison between dominant and non-dominant shoulders during unilateral flexion and abduction

Degrees of stochasticity in particle swarm optimization

This paper illustrates the importance of independent, component-wise stochastic scaling values, from both a theoretical and empirical perspective. It is shown that a swarm employing scalar stochasticity in the particle update equation is unable to express every point in the search space if the problem dimensionality is sufficiently large in comparison with the swarm size. The theoretical result is emphasized by an empirical experiment which shows that a swarm using scalar stochasticity performs significantly worse when the optimum is not in the span of its initial positions. It is also demonstrated that even when the problem dimensionality allows a scalar swarm to reach the optimum, a swarm with component-wise stochasticity significantly outperforms the scalar swarm. This result is extended by considering different degrees of stochasticity, in which groups of components share the same stochastic scalar. It is demonstrated on a large range of benchmark functions that swarms with dimensional coupling (including scalar swarms in the most extreme case) perform significantly worse than a swarm with component-wise stochasticity. The paper also shows that, contrary to previous results in the field, a swarm with component-wise stochasticity is not biased towards the subspace within which it is initialized. The misconception is shown to have arisen in the previous literature due to overzealous normalization when measuring swarm movement, which is corrected in this paper.

Multi-dimensional force sensor for haptic interaction: a review

Haptic interaction plays an important role in the virtual reality technology, which let a person not only view the 3D virtual environment but also realistically touch the virtual environment. As a key part of haptic interaction, force feedback has become an essential function for the haptic interaction. Therefore, multi-dimensional force sensors are widely used in the fields of virtual reality and augmented reality. In this paper, some conventional multi-dimensional force sensors based on different measurement principles, such as resistive, capacitive, piezoelectric, are briefly introduced. Then the mechanical structures of the elastic body of multi-dimensional force sensors are reviewed. It is obvious that the performance of the multi-dimensional force sensor is mainly dependent upon the mechanical structure of elastic body. Furthermore, the calibration process of the force sensor is analyzed, and problems in calibration are discussed. Interdimensional coupling error is one of the main factors affecting the measurement precision of the multi-dimensional force sensors. Therefore, reducing or even eliminating dimensional coupling error becomes a fundamental requirement in the design of multi-dimensional force sensors, and the decoupling state-of-art of the multi-dimensional force sensors are introduced in this paper. At last, the trends and current challenges of multi-dimensional force sensing technology are proposed.

Research progress of photocatalytic sterilization over semiconductors.

Considering the situation that environmental issues become more serious day by day, research on practical applications of semiconductor photocatalysis for environmental purification has attracted broad attention, including the remediation of water pollution, air contaminant treatment, photocatalytic sterilization etc., among which the application of semiconductor photocatalytic properties for the disinfection of soil surfaces, air and water, such as TiO2, is of great interest. In this paper, we give an overview of the photocatalytic antibacterial ability of TiO2 and other novel carbon material semiconductors. We have introduced the background information of photocatalytic disinfection and the disinfection mechanism of pure TiO2. Furthermore, other modified TiO2 sterilization materials are listed, such as those with doping modification. In addition, some novel carbon based nanomaterials are discussed as well in this review, for instance, g-C3N4, carbon nanotubes and graphene nanosheets. Finally, we present an outlook over two dimensional (2D) materials and coupling techniques based on the combination of photocatalysis and other sterilization technologies.

Two–dimensional g–C3N4/α–AgAl0.4Ga0.6O2 p–n heterostructure with improved visible–light–driven photocatalytic property

Design and preparation of two–dimensional heterostructure is an effective strategy to obtain enhanced photoelectrochemical and photocatalytic performances. Herein, two–dimensional g–C3N4/α–AgAl0.4Ga0.6O2 p–n heterostructure is for the first time synthesized by phase transition method under hydrothermal treatment. It is found that the heterostructure shows the coexistence of two phases with high crystallinity. Platelet-like α–AgAl0.4Ga0.6O2 and g–C3N4 sheets couple each other face to face, resulting in the formation of close interfaces and efficient heterojunctions. UV–vis absorption of the heterostructure is modulated efficiently by controlling the phase component. When utilized as photocatalysts for MO degradation under visible light irradiation, the g–C3N4/α–AgAl0.4Ga0.6O2 with a molar ratio of 0.75 exhibits the most excellent photocatalytic performance with a rate constant of 0.0227 min−1. The further investigation of the photoelectrochemical property including small diameter of the arc radius and maximum photocurrent indicates that the separation efficiency of electron–hole pairs is greatly improved through heterojunctions with two–dimensional coupling interfaces. Besides, the reaction kinetics and the photocatalytic mechanism related to the energy band are proposed for degrading organic pollutants. The results prove that the g–C3N4/α–AgAl0.4Ga0.6O2 heterostructure has great potential application in photocatalysis for eliminating organic pollutants.

Travelling waves and conservation laws of a (2+1)-dimensional coupling system with Korteweg-de Vries equation

Abstract In this paper we study a (2+1)-dimensional coupling system with the Korteweg-de Vries equation, which is associated with non-semisimple matrix Lie algebras. Its Lax-pair and bi-Hamiltonian formulation were obtained and presented in the literature. We utilize Lie symmetry analysis along with the (G′/G)–expansion method to obtain travelling wave solutions of this system. Furthermore, conservation laws are constructed using the multiplier method.

Energy efficient predictive control for vapor compression refrigeration cycle systems

Vapor compression refrigeration cycle system is a high dimensional coupling thermodynamic system for which the controller design is a great challenge. In this paper, a model predictive control based energy efficient control strategy which aims at maximizing the system efficiency is proposed. Firstly, according to the mass and energy conservation law, an analysis on the nonlinear relationship between superheat and cooling load is carried out, which can produce the maximal effect on the system performance. Then a model predictive control &#x0028 MPC &#x0029 based controller is developed for tracking the calculated setting curve of superheat degree and pressure difference based on model identified from data which can be obtained from an experimental rig. The proposed control strategy maximizes the coefficient of performance &#x0028 COP &#x0029 which depends on operating conditions, in the meantime, it meets the changing demands of cooling capacity. The effectiveness of the control performance is validated on the experimental rig.

Observation of Floquet bands in driven spin-orbit-coupled Fermi gases

Periodic driving of a quantum system can significantly alter its energy bands and even change the band topology, opening a completely new avenue for engineering novel quantum matter. Although important progress has been made recently in measuring topological properties of Floquet bands in different systems, direct experimental measurement of Floquet band dispersions and their topology change is still demanding. Here we directly measure Floquet band dispersions in a periodically driven spin-orbit coupled ultracold Fermi gas. Using spin injection radio-frequency spectroscopy, we observe that the Dirac point originating from two dimensional spin-orbit coupling can be manipulated to emerge at the lowest or highest two dressed bands by fast modulating Raman laser frequencies, demonstrating topological change of Floquet bands. Our work will provide a powerful tool for understanding fundamental Floquet physics as well as engineering exotic topological quantum matter.

Dimensional coupling-induced current reversal in two-dimensional driven lattices.

We show that the direction of directed particle transport in a two-dimensional ac-driven lattice can be dynamically reversed by changing the structure of the lattice in the direction perpendicular to the applied driving force. These structural changes introduce dimensional coupling effects, the strength of which governs the timescale of the current reversals. The underlying mechanism is based on the fact that dimensional coupling allows the particles to explore regions of phase space which are inaccessible otherwise. The experimental realization for cold atoms in ac-driven optical lattices is discussed.

I-Love-Q relations for neutron stars in dynamical Chern Simons gravity

Neutron stars are ideal to probe, not only nuclear physics, but also strong-field gravity. Approximate universal relations insensitive to the star’s internal structure exist among certain observables and are useful in testing general relativity, as they project out the uncertainties in the equation of state. One such set of universal relations between the moment of inertia (I), the tidal Love number and the quadrupole moment (Q) has been studied both in general relativity and in modified theories. In this paper, we study the relations in dynamical Chern–Simons gravity, a well-motivated, parity-violating effective field theory, extending previous work in various ways. First, we study how projected constraints on the theory using the I-Love relation depend on the measurement accuracy of I with radio observations and that of the Love number with gravitational-wave observations. Provided these quantities can be measured with future observations, we find that the latter could place bounds on dynamical Chern–Simons gravity that are six orders of magnitude stronger than current bounds. Second, we study the I–Q and Q-Love relations in this theory by constructing slowly-rotating neutron star solutions to quadratic order in spin. We find that the approximate universality continues to hold in dynamical Chern–Simons gravity, and in fact, it becomes stronger than in general relativity, although its existence depends on the normalization of the dimensional coupling constant of the theory. Finally, we study the variation of the eccentricity of isodensity contours inside a star and its relation to the degree of universality. We find that, in most cases, the eccentricity variation is smaller in dynamical Chern–Simons gravity than in general relativity, providing further support to the idea that the approximate self-similarity of isodensity contours is responsible for universality.

Design and Analysis of the Measurement Characteristics of a Bidirectional-Decoupling Over-Constrained Six-Dimensional Parallel-Mechanism Force Sensor.

The measurement of large forces and the presence of errors due to dimensional coupling are significant challenges for multi-dimensional force sensors. To address these challenges, this paper proposes an over-constrained six-dimensional force sensor based on a parallel mechanism of steel ball structures as a measurement module. The steel ball structure can be subject to rolling friction instead of sliding friction, thus reducing the influence of friction. However, because the structure can only withstand unidirectional pressure, the application of steel balls in a six-dimensional force sensor is difficult. Accordingly, a new design of the sensor measurement structure was designed in this study. The static equilibrium and displacement compatibility equations of the sensor prototype’s over-constrained structure were established to obtain the transformation function, from which the forces in the measurement branches of the proposed sensor were then analytically derived. The sensor’s measurement characteristics were then analysed through numerical examples. Finally, these measurement characteristics were confirmed through calibration and application experiments. The measurement accuracy of the proposed sensor was determined to be 1.28%, with a maximum coupling error of 1.98%, indicating that the proposed sensor successfully overcomes the issues related to steel ball structures and provides sufficient accuracy.

Improved HPC method for nonlinear wave tank

The recently developed Harmonic Polynomial Cell (HPC) method has been proved to be a promising choice for solving potential-flow Boundary Value Problem (BVP). In this paper, a flux method is proposed to consistently deal with the Neumann boundary condition of the original HPC method and enhance the accuracy. Moreover, fixed mesh algorithm with free surface immersed is developed to improve the computational efficiency. Finally, a two dimensional (2D) multi-block strategy coupling boundary-fitted mesh and fixed mesh is proposed. It limits the computational costs and preserves the accuracy. A fully nonlinear 2D numerical wave tank is developed using the improved HPC method as a verification.

Surface modification of TiO 2 nanoparticle by three dimensional silane coupling agent and preparation of polyamide/modified- TiO 2 nanocomposites for removal of Cr (VI) from aqueous solutions

Abstract In the present investigation, the goal was the preparation, characterization and surface morphology of polyamide/modified-TiO 2 nanocomposites (PA/m-TiO 2 NCs). At first, a soluble aromatic PA was synthesized by direct polycondensation reaction of the synthesized diacid and 1,3-phenylenediamine in molten tetrabutylammonium bromide (TBAB) with good yield and moderate inherent viscosity. The structure and purity of these compounds were confirmed by different techniques. For the improvement of TiO 2 nanoparticles dispersion and enhancing interactions between nanoparticles and polymeric matrix, the surface of TiO 2 was successfully modified by 1,3,5-triazine based silane coupling agent. The functionalized nanoparticles were then inscribed in 0, 5, 10 and 15 wt.% into polymer matrix. The resulting hybrids were characterized by Fourier transform-infrared spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The TGA of the obtained PA/m-TiO 2 NCs proves the enhancement in the thermal stability with an increase in the percentage of titania nanoparticles. It was further investigated for Cr(VI) ion removal by optimizing the parameters including pH, contact time and concentration. Also, adsorption kinetics and adsorption isotherms of this polymer were investigated.

Numerical simulation of limited-entry multi-cluster fracturing in horizontal well

Limited-entry technique has become one of the primary engineering approaches to promote even growth of multiple fractures in hydraulic fracturing. In this paper, we developed a three dimensional (3D) hydro-mechanical coupling finite element model to investigate the simultaneous growth of multiple fractures during the multi-stage/multi-cluster fracturing of horizontal wells. The focus is to elaborate the effect of entry friction on the growth of fractures initiated from multiple perforation clusters. To this end, we developed a new element to account for the local pressure drop due to perforation entry friction and thus to dynamically partition the flow of the fracturing fluid among multiple fractures. The effectiveness of this element was validated by two element-level test examples. Propagation of the hydraulic fractures was modeled by using a zero-thickness cohesive element, which can simulate the fracture propagation and fluid flow within the fractures in a completely coupled manner. With this 3D model, parametric studies were performed to illustrate the impact of perforation parameters and stress shadowing on the simultaneous propagation of fractures from multiple perforation clusters within a stage. Results indicate that a sufficiently large perforation pressure drop can counteract the stress shadowing among the multiple fractures and can help to equalize the length of multiple fractures. The differences of down-hole pressures among cases with different perforation parameters are too small to be detected in the field, which indicates that it is hard to tell from the pressure record alone whether or not all the fractures are equally growing. It is also found that the smaller variance of fracture lengths, the bigger total area of the fractures.

Three Dimensional Magnetic-Mechanical Coupling Analysis of a Permanent Magnet Motor by the Magnetic Beads Method with Coarse-to-Fine Beads Model

Three Dimensional Magnetic-Mechanical Coupling Analysis of a Permanent Magnet Motor by the Magnetic Beads Method with Coarse-to-Fine Beads Model

Lightning Strike Ablation Damage Influence Factors Analysis of Carbon Fiber/Epoxy Composite Based on Coupled Electrical-Thermal Simulation

According to the mathematical analysis model constructed on the basis of energy-balance relationship in lightning strike, and accompany with the simplified calculation strategy of composite resin pyrolysis degree dependent electrical conductivity, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate suffered from lightning current was established based on ABAQUS, to elucidate the effects of lighting current waveform parameters and thermal/electrical properties of composite laminate on the extent of ablation damage. Simulated predictions agree well with the composite lightning strike directed effect experimental data, illustrating the potential accuracy of the constructed model. The analytical results revealed that extent of composite lightning strike ablation damage can be characterized by action integral validly, there exist remarkable power function relationships between action integral and visual damage area, projected damage area, maximum damage depth and damage volume of ablation damage, and enhancing the electrical conductivity and specific heat of composite, ablation damage will be descended obviously, power function relationships also exist between electrical conductivity, specific heat and ablation damage, however, the impact of thermal conductivity on the extent of ablation damage is not notable. The conclusions obtained provide some guidance for composite anti-lightning strike structure-function integration design.

Evaluation model coupling exploitable groundwater resources and land subsidence control in regional loose sediments

The loose sediments in the Yangtze River Delta, the North China Plain, the plain of Northern Jiangsu and other districts in China are of great thickness, complex in structure and abundant in groundwater. Groundwater overexploitation easily results in geological disasters of land subsidence. Aiming at the issues, assessment models coupling exploitable groundwater resources and land subsidence control in regional loose sediments were brought up in this paper. The two models were: (1) a three dimensional groundwater seepage model with land subsidence based on the one dimensional Terzaghi consolidation theory; (2) a three dimensional full coupling model on groundwater seepage and land subsidence based on the Biot consolidation theory to simulate and calculate. It can be used to simulate and calculate the problems in real situations. Thus, the groundwater seepage and land subsidence were coupled together in the model to evaluate the amount of exploitable groundwater under the specific requirements of land subsidence control. The full coupling model, which considers the non-linear characteristics of soil mass and the dynamic changes of soil permeability with stress state based on the Biot consolidation theory, is more coincident with the variation characteristics of the hydraulic and mechanical properties of soil mass during the pumping process, making the evaluation results more scientific and reasonable.

Lightning Strike Ablation Damage Characteristic Analysis for Carbon Fiber/Epoxy Composite Laminate with Fastener

In order to analyze the lightning strike ablation damage characteristic of composite laminate with fastener, based on the energy-balance relationship in lightning strike, mathematical analysis model of ablation damage of composite laminate with fastener was constructed. According to the model, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate with fastener suffered from lightning current was established based on ABAQUS, and lightning strike ablation damage characteristic was analyzed. Analytical results reveal that lightning current could conduct through the thickness direction of the laminate due to the existence of metallic fastener, and then distribute to all layers, finally conducted in-the-plane of each layer, conductive ability of different layup orientations depend on potential distribution and in-the-plane electrical conductivity along potential gradient declining direction; different potential boundaries correspond to different potential distribution in each layer, and result in conductive ability of different layup orientations was changed, then caused different lightning strike ablation damage distribution. According to the investigation in this paper, we can recognize the lightning strike ablation damage characteristic of composite laminate with fastener qualitatively.

Integrated guidance and control for hypersonic vehicles in dive phase with multiple constraints

An adaptive integrated guidance and control (IGC) scheme for hypersonic vehicle in dive phase is proposed in this paper. The three dimensional (3D) coupling relative dynamics and the explicit relations between line-of-sight (LOS) angles and the angle of attack and sideslip angle are described based on analytical aerodynamic models of the hypersonic vehicle. A coupling and full states IGC design model in strict feedback form is derived by combing the 3D relative dynamics and the equations of the rotational loop. In the deduction of the novel IGC scheme, the 3D impact angles and constraints of the normal overload, commands of Euler angles and three-channel body rates are accounted for. The solution of a ten-order, nonlinear, and uncertain IGC frame control system is converted into an output tuning problem. Pseudo-inputs associated with rotational motion are depicted using adaptive dynamic surface control theory. The desired control surface fin deflections are derived based on the block dynamic surface approach. The Lyapunov function consisted of dynamic surfaces, errors of the filters, and estimation errors is conducted, states of the IGC closed-loop system are proved to be uniformly ultimate bounded. Finally, the effectiveness and robustness of the adaptive IGC scheme are investigated and verified using six-degree-of-freedom (6DoF) nonlinear simulation studies.

Modeling metapopulation dynamics of HIV epidemic on a linear lattice with nearest neighbour coupling

<p>Many mathematical models for the spread of infectious diseases in a population assume homogeneous mixing, but due to spatial distribution, there exist distinct patches with unique disease dispersion dynamics, especially if between patch mixing due to travel and migration is limited. In this paper, three levels of disease status in a - patch metapopulation was studied using a simple SIR-HIV epidemic model in a one dimensional nearest neighbour coupling lattice. The basic reproductive ratio , which is a function of coupling strength , is shown to affect stability characteristics of equilibrium points. The disease free equilibrium (DFE) is globally asymptotically stable irrespective of the value of but the stability of the endemic equilibrium point (EEP) depends on the coupling strength . It was found that at the critical value of coupling strength , the subpopulations dynamics are synchronized while for the subpopulation dynamics are independent. Patch isolation strategy for the control of HIV dispersion requires a critical coupling strength of . This interaction restriction reduces to values less than one, and the disease will be eliminated, making isolation effective. Demographic and epidemiological parameters of Vihiga County in Kenya were used in the study.</p>