Binary Bose-Einstein condensates in a disordered time-dependent potential

We study the non-equilibrium evolution of binary Bose-Einstein condensates in the presence of weak random potential with a Gaussian correlation function using the time-dependent perturbation theory. We apply this theory to construct a closed set of equations that highlight the role of the spectacular interplay between the disorder and the interspecies interactions in the time evolution of the density induced by disorder in each component. It is found that this latter increases with time favoring localization of both species. The time scale at which the theory remains valid depends on the respective system parameters. We show analytically and numerically that such a system supports a steady state that periodically changing during its time propagation. The obtained dynamical corrections indicate that disorder may transform the system into a stationary out-of-equilibrium states. Understanding this time evolution is pivotal for the realization of Floquet condensates.

Overcoming Kinematic Singularities for Motion Control in a Caster Wheeled Omnidirectional Robot

Omnidirectional planar robots are common these days due to their high mobility, for example in human–robot interactions. The motion of such mechanisms is based on specially designed wheels, which may vary when different terrains are considered. The usage of actuated caster wheels (ACW) may enable the usage of regular wheels. Yet, it is known that an ACW robot with three actuated wheels needs to overcome kinematic singularities. This paper introduces the kinematic model for an ACW omni robot. We present a novel method to overcome the kinematic singularities of the mechanism’s Jacobian matrix by performing the time propagation in the mechanism’s configuration space. We show how the implementation of this method enables the estimation of caster wheels’ swivel angles by tracking the plate’s velocity. We present the mechanism’s kinematics and trajectory tracking in real-world experimentation using a novel robot design.

Propogation LWD Tool Analysing for Better Saturation Estimation in High Angle Horizontal Well Conditions

Multidepth electromagnetic logging tool is considered as traditional measurements of formation resistivity estimation while drilling. When considering data in wells with high angles trajectory, more than 70 degrees, the resistivity measurements could be affected by several factors associated with geological conditions and logging tool specifications. As the result, during water saturation estimation formation properties could be distorted, which will lead to significant effect of reservoir properties assessment and the design of the horizontal well completion. Within the framework of this paper, various methods of influence on the resistivity readings will be considered, especially with cross boundary effects and reservoir formations with anisotropy. At the same time, propagation resistivity logging technologies while drilling with interpretation and boundary propagation technologies will be observed, which has tilted azimuthal oriented receivers for geosteering service of horizontal wells and additionally helps with take into account of boundary enflurane on standard resistivity logging.

Propagation Vectors Facilitate Differentiation between Conduction Block, Slow Conduction and Wavefront Collision

Background - Differentiation between conduction block, slow conduction, and wavefront collision can be difficult using activation mapping alone, often requiring differential pacing. Therefore, a real-time method for determination of complex patterns of conduction may be desired. We hereby report a novel algorithm for displaying propagation vectors, allowing differentiation between complex patterns of conduction and facilitating real-time detection of block during ablation. Methods - In 10 swine, a chronic transcaval ablation line with an intentional gap or complete block was created, simulating conduction block, slow conduction and wavefront collision. The line was mapped during atrial pacing using Carto 3 and a novel high-resolution array that includes 48 mini-electrodes (surface area-0.9mm 2 , spacing 2.4mm) distributed over 6 splines (Optrell™, Biosense Webster). Propagation vectors were created from unipolar waveforms of adjacent electrodes along and across splines that were acquired at single beats. In order to examine the utility of propagation vectors for detection conduction block during ablation, a cavotricuspid isthmus line (CTI) was created during coronary sinus pacing with the array positioned lateral to the line. Results - Propagation vectors detected the gap in all 6 interrupted ablation line, while activation maps only identified gap in 3/6 lines; in the remainder, activation maps alone could not differentiate between conduction block, slow conduction or wavefront collision. Propagation vectors accurately determined block in all 4 contiguous ablation line, while activation maps suggested conduction block or was indeterminant due to wavefront collision in 2/4 lines. CTI block was detected during ablation by abrupt reversal of propagation vectors from a lateral to a septal direction and acute reconnection was detected by reversal of the propagating vectors back to a lateral direction. Conclusions - Real-time propagation vectors enhance the ability of standard activation maps to differentiate between complex patterns of conduction, including determination of conduction block during ablation.

Giant exciton-enhanced shift currents and direct current conduction with subbandgap photo excitations produced by many-electron interactions

Shift current is a direct current generated from nonlinear light–matter interaction in a noncentrosymmetric crystal and is considered a promising candidate for next-generation photovoltaic devices. The mechanism for shift currents in real materials is, however, still not well understood, especially if electron–hole interactions are included. Here, we employ a first-principles interacting Green’s-function approach on the Keldysh contour with real-time propagation to study photocurrents generated by nonlinear optical processes under continuous wave illumination in real materials. We demonstrate a strong direct current shift current at subbandgap excitation frequencies in monolayer GeS due to strongly bound excitons, as well as a giant excitonic enhancement in the shift current coefficients at above bandgap photon frequencies. Our results suggest that atomically thin two-dimensional materials may be promising building blocks for next-generation shift current devices.

Reliable Time Propagation Algorithms for PMF and RBPMF

This paper addresses the reliable time propagation algorithms for Point Mass Filter (PMF) and Rao–Blackwellized PMF (RBPMF) for the nonlinear estimaton problem. The conventional PMF and RBPMF process the probability diffusion for the time propagation with the direct sampled-values of the process noise. However, if the grid interval is not dense enough, it fails to represent the statistical characteristics of the noise accurately so the performance might deteriorate. To overcome that problem, we propose time propagation convolution algorithms adopting Moment Matched Gaussian Kernel (MMGK) on regular grids through mass linear interpolation. To extend the dimension of the MMGK that can accurately describe the noise moments up to the kernel length, we propose the extended MMGK based on the outer tensor product. The proposed time propagation algorithms using one common kernel through the mass linear interpolation not only improve the performance of the filter but also significantly reduce the computational load. The performance improvement and the computational load reduction of the proposed algorithms are verified through numerical simulations for various nonlinear models.