9,515 research outputs found
TZC: Efficient Inter-Process Communication for Robotics Middleware with Partial Serialization
Inter-process communication (IPC) is one of the core functions of modern
robotics middleware. We propose an efficient IPC technique called TZC (Towards
Zero-Copy). As a core component of TZC, we design a novel algorithm called
partial serialization. Our formulation can generate messages that can be
divided into two parts. During message transmission, one part is transmitted
through a socket and the other part uses shared memory. The part within shared
memory is never copied or serialized during its lifetime. We have integrated
TZC with ROS and ROS2 and find that TZC can be easily combined with current
open-source platforms. By using TZC, the overhead of IPC remains constant when
the message size grows. In particular, when the message size is 4MB (less than
the size of a full HD image), TZC can reduce the overhead of ROS IPC from tens
of milliseconds to hundreds of microseconds and can reduce the overhead of ROS2
IPC from hundreds of milliseconds to less than 1 millisecond. We also
demonstrate the benefits of TZC by integrating with TurtleBot2 that are used in
autonomous driving scenarios. We show that by using TZC, the braking distance
can be shortened by 16% than ROS
Exceptional Points in a Non-Hermitian Topological Pump
We investigate the effects of non-Hermiticity on topological pumping, and
uncover a connection between a topological edge invariant based on topological
pumping and the winding numbers of exceptional points. In Hermitian lattices,
it is known that the topologically nontrivial regime of the topological pump
only arises in the infinite-system limit. In finite non-Hermitian lattices,
however, topologically nontrivial behavior can also appear. We show that this
can be understood in terms of the effects of encircling a pair of exceptional
points during a pumping cycle. This phenomenon is observed experimentally, in a
non-Hermitian microwave network containing variable gain amplifiers.Comment: 7 pages, 7 figures. The first author did the experiment, and the
second author did the theoretical stud
The evolution of magnetic structure driven by a synthetic spin-orbit coupling in two-component Bose-Hubbard model
We study the evolution of magnetic structure driven by a synthetic spin-orbit
coupling in a one-dimensional two-component Bose-Hubbard model. In addition to
the Mott insulator-superfluid transition, we found in Mott insulator phases a
transition from a gapped ferromagnetic phase to a gapless chiral phase by
increasing the strength of spin-orbit coupling. Further increasing the
spin-orbit coupling drives a transition from the gapless chiral phase to a
gapped antiferromagnetic phase. These magnetic structures persist in superfluid
phases. In particular, in the chiral Mott insulator and chiral superfluid
phases, incommensurability is observed in characteristic correlation functions.
These unconventional Mott insulator phase and superfluid phase demonstrate the
novel effects arising from the competition between the kinetic energy and the
spin-orbit coupling.Comment: 9 fig; English polished, note adde
Hubble Tension: The Evidence of New Physics
The CDM model provides a good fit to most astronomical observations
but harbors large areas of phenomenology and ignorance. With the improvements
in the precision and number of observations, discrepancies between key
cosmological parameters of this model have emerged. Among them, the most
notable tension is the 4 to 6 deviation between the Hubble
constant () estimations measured by the local distance ladder and the
cosmic microwave background (CMB) measurement. In this review, we revisit the
tension based on the latest research and sort out evidence from
solutions to this tension that might imply new physics beyond the CDM
model. The evidence leans more towards modifying the late-time universe.Comment: 39 pages, 6 figures, 3 tables, accepted for publication in Universe
(invited review for Special Issue: Advances in Astrophysics and Cosmology -
in Memory of Prof. Tan Lu
- …