7,137 research outputs found
Euclidean Distance Matrices: Essential Theory, Algorithms and Applications
Euclidean distance matrices (EDM) are matrices of squared distances between
points. The definition is deceivingly simple: thanks to their many useful
properties they have found applications in psychometrics, crystallography,
machine learning, wireless sensor networks, acoustics, and more. Despite the
usefulness of EDMs, they seem to be insufficiently known in the signal
processing community. Our goal is to rectify this mishap in a concise tutorial.
We review the fundamental properties of EDMs, such as rank or
(non)definiteness. We show how various EDM properties can be used to design
algorithms for completing and denoising distance data. Along the way, we
demonstrate applications to microphone position calibration, ultrasound
tomography, room reconstruction from echoes and phase retrieval. By spelling
out the essential algorithms, we hope to fast-track the readers in applying
EDMs to their own problems. Matlab code for all the described algorithms, and
to generate the figures in the paper, is available online. Finally, we suggest
directions for further research.Comment: - 17 pages, 12 figures, to appear in IEEE Signal Processing Magazine
- change of title in the last revisio
A Software-Defined Multi-Element VLC Architecture
In the modern era of radio frequency (RF) spectrum crunch, visible light
communication (VLC) is a recent and promising alternative technology that
operates at the visible light spectrum. Thanks to its unlicensed and large
bandwidth, VLC can deliver high throughput, better energy efficiency, and low
cost data communications. In this article, a hybrid RF/VLC architecture is
considered that can simultaneously provide light- ing and communication
coverage across a room. Considered architecture involves a novel multi-element
hemispherical bulb design, which can transmit multiple data streams over light
emitting diode (LED) modules. Simulations considering various VLC transmitter
configurations and topologies show that good link quality and high spatial
reuse can be maintained in typical indoor communication scenarios
Automated sequence and motion planning for robotic spatial extrusion of 3D trusses
While robotic spatial extrusion has demonstrated a new and efficient means to
fabricate 3D truss structures in architectural scale, a major challenge remains
in automatically planning extrusion sequence and robotic motion for trusses
with unconstrained topologies. This paper presents the first attempt in the
field to rigorously formulate the extrusion sequence and motion planning (SAMP)
problem, using a CSP encoding. Furthermore, this research proposes a new
hierarchical planning framework to solve the extrusion SAMP problems that
usually have a long planning horizon and 3D configuration complexity. By
decoupling sequence and motion planning, the planning framework is able to
efficiently solve the extrusion sequence, end-effector poses, joint
configurations, and transition trajectories for spatial trusses with
nonstandard topologies. This paper also presents the first detailed computation
data to reveal the runtime bottleneck on solving SAMP problems, which provides
insight and comparing baseline for future algorithmic development. Together
with the algorithmic results, this paper also presents an open-source and
modularized software implementation called Choreo that is machine-agnostic. To
demonstrate the power of this algorithmic framework, three case studies,
including real fabrication and simulation results, are presented.Comment: 24 pages, 16 figure
An anytime tree search algorithm for two-dimensional two- and three-staged guillotine packing problems
[libralesso_anytime_2020] proposed an anytime tree search algorithm for the
2018 ROADEF/EURO challenge glass cutting problem
(https://www.roadef.org/challenge/2018/en/index.php). The resulting program was
ranked first among 64 participants. In this article, we generalize it and show
that it is not only effective for the specific problem it was originally
designed for, but is also very competitive and even returns state-of-the-art
solutions on a large variety of Cutting and Packing problems from the
literature. We adapted the algorithm for two-dimensional Bin Packing, Multiple
Knapsack, and Strip Packing Problems, with two- or three-staged exact or
non-exact guillotine cuts, the orientation of the first cut being imposed or
not, and with or without item rotation. The combination of efficiency, ability
to provide good solutions fast, simplicity and versatility makes it
particularly suited for industrial applications, which require quickly
developing algorithms implementing several business-specific constraints. The
algorithm is implemented in a new software package called PackingSolver
A proposed segmented precast concrete spherical cap: geometry, structural stability and construction
This study proposes the design and construction of a concrete spherical cap composed of uniformly-shaped precast doubly-curved panels based on spherical division techniques. A numerical structural analysis is conducted to study the failure behavior of the segmented structure and the capacity of the joints by using finite element modeling techniques to model the concrete material behavior, boundary conditions and intermediate joints of the precast panels. An experimental analysis is conducted to verify the capacity of the structure and the reliability of the modeling techniques, and to study the feasibility of the proposed panel prefabrication and assembly method. The results of this study demonstrate that the proposed precast system and connection design perform efficiently when compared to the monolithically-cast counterpart, particularly under uniform loading conditions. Additional insights on the properties and solution parameters of finite element modelling of concrete shell structures are presented based on the structural analysis of this work. The study concludes the ability of the proposed geometric design and construction method to enhance the prefabrication and construction efficiency with little effect on the structural capacity within the context of the selected geometry and conducted load tests, and recommends further parameters to study for design and construction optimization
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