Dual Degrees Of Freedom Research Articles

Design, kinematics, and prototyping of a gripping mechanism to adapt large space

This manuscript introduces a symmetrical gripping mechanism, a significant piece of robotic equipment, adept at adjusting to the variable dimensions of disparate objects within an extensive range. The innovative mechanism presented in this treatise has dual degrees of freedom (DOF), and its parameters can be customized to satisfy diverse requirements. Symbolic computation is employed to dissect both the forward and inverse kinematics of the mechanism. Furthermore, the requisite driving force of the mechanism, when paired with parameterized objects, is discussed. Ultimately, a methodology is suggested for discerning the mechanism’s parameters in relation to variously grasped widths and forces. The article concludes with the introduction of a prototype construction process. Experimental results substantiate the effectiveness and functionality of the proposed mechanism.

Tuning valley splitting and magnetic anisotropy of multiferroic CuMP2X6 (M=Cr,V;X=S,Se) monolayer

Monolayer $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ $(M=\mathrm{Cr},\mathrm{V};X=\mathrm{S},\mathrm{Se})$ has been attracting increasing attention due to the ferromagnetism derived from the indirect exchange interaction between Cr (V) atoms and the ferroelectricity originating from the spontaneous displacement of Cu atoms. Using first-principles calculations, we predicted the intrinsic valley splittings and anomalous valley Hall effect in $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ monolayers. In addition, the valley splittings and Berry curvature are independent of the orientation of out of plane (OOP) ferroelectric polarization, which makes it a promising storage device with dual degrees of freedom in ferroelectric polarization and ferrovalleys. Due to the variations in the energy of the spin-dependent valence-band maximum (VBM) and orbital compositions of the valleys, the magnitude of valley splitting at VBM can be effectively tuned by the biaxial strain and external electric field. Large OOP magnetic anisotropy can be obtained by changing the energy and occupation (unoccupation) states of $d$ orbital compositions through strain and charge doping, respectively, and the magnetic anisotropy of $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ increases with increasing tensile biaxial strain from \ensuremath{-}5% to 5%. Our research results are expected to tune the valley splittings and magnetic anisotropy of $\mathrm{Cu}M{\mathrm{P}}_{2}{X}_{6}$ and to help understand the physical mechanism.

A novel tunable frequency selective surface absorber with dual-DOF for broadband applications

A novel tunable frequency selective surface (FSS) with dual-degrees of freedom (DOF) is presented, and firstly applied to broadband absorber. Based on a simple prototype unit cell resonator, an approach for achieving multi-resonances is studied. A unit cell pattern with gradient edges is discussed, and variable resistor and variable capacitor are introduced to fully utilize its characteristic of multi-resonances. Bias line is designed to provide bias voltage respectively for two variable devices and provide two operational DOF for FSS. Simulation and measurement results both show that the tunable FSS absorber with dual-DOF has wideband absorption with the reflectivity below -10 dB in 1-5 GHz and with a total thickness of about 10 mm.

Characterizing symmetry breaking patterns in a lattice by dual degrees of freedom

A duality transformation in quantum field theory is usually established first through partition functions. It is always important to explore the dual relations between various correlation functions in the transformation. Here, we explore such a dual relation to study quantum phases and phase transitions in an extended boson Hubbard model at 1/3 (2/3) filling on a triangular lattice. We develop systematically a simple and effective way to use the vortex degrees of freedom on dual lattices to characterize both the density wave and valence bond symmetry breaking patterns of the boson insulating states in the direct lattices. In addition to a checkerboard charge density wave (X-CDW) and a stripe CDW, we find a novel CDW-VBS phase which has both local CDW and local valence bond solid (VBS) orders. Implications for Quantum Monte Carlo simulations are addressed. The possible experimental realizations of cold atoms loaded on optical lattices are discussed.

Muscle Synergies at the Elbow in Static and Oscillating Isometric Torque Tasks with Dual Degrees of Freedom

This study's aim was to identify the effect of oscillation of torques in isometric tasks under identical mechanical conditions on the muscle synergies used. It was hypothesized that bi-functional muscles would play a lesser role in torque oscillation, because they would also generate an undesired oscillation. Thus, changes in muscle synergies were expected as a consequence of oscillation in torque generation. The effect of the trajectory of torque generation was investigated in dual-degrees-of-freedom submaximal isometric oscillation torque tasks at the elbow. The torques were flexion-extension and supination-pronation. Oscillation torques were compared with static torque generations at four torque positions during oscillation. Muscle activity was determined with surface electromyography. Compared with the static torque tasks, the oscillation tasks showed an overall increased muscle activity. The oscillation tasks, however, showed similar activity patterns and muscle synergies compared to the static composite tasks. It was found that the motor system is well able to control different orthogonal combinations of slow torque oscillations and constant torques by employing a single oscillating muscle synergy.

Nonabelian duality and solvable large lattice systems

We introduce the basics of the nonabelian duality transformation of SU(N) or U(N) vector-field models defined on a lattice. The dual degrees of freedom are certain species of the integer-valued fields complemented by the symmetric groups' \otimes_{n} S(n) variables. While the former parametrize relevant irreducible representations, the latter play the role of the Lagrange multipliers facilitating the fusion rules involved. As an application, I construct a novel solvable family of SU(N) D-matrix systems graded by the rank 1\leq{k}\leq{(D-1)} of the manifest [U(N)]^{\oplus k} conjugation-symmetry. Their large N solvability is due to a hidden invariance (explicit in the dual formulation) which allows for a mapping onto the recently proposed eigenvalue-models \cite{Dub1} with the largest k=D symmetry. Extending \cite{Dub1}, we reconstruct a D-dimensional gauge theory with the large N free energy given (modulo the volume factor) by the free energy of a given proposed 1\leq{k}\leq{(D-1)} D-matrix system. It is emphasized that the developed formalism provides with the basis for higher-dimensional generalizations of the Gross-Taylor stringy representation of strongly coupled 2d gauge theories.