183 research outputs found
A Task-Interdependency Model of Complex Collaboration Towards Human-Centered Crowd Work
Models of crowdsourcing and human computation often assume that individuals
independently carry out small, modular tasks. However, while these models have
successfully shown how crowds can accomplish significant objectives, they can
inadvertently advance a less than human view of crowd workers and fail to
capture the unique human capacity for complex collaborative work. We present a
model centered on interdependencies -- a phenomenon well understood to be at
the core of collaboration -- that allows one to formally reason about diverse
challenges to complex collaboration. Our model represents tasks as an
interdependent collection of subtasks, formalized as a task graph. We use it to
explain challenges to scaling complex collaborative work, underscore the
importance of expert workers, reveal critical factors for learning on the job,
and explore the relationship between coordination intensity and occupational
wages. Using data from O*NET and the Bureau of Labor Statistics, we introduce
an index of occupational coordination intensity to validate our theoretical
predictions. We present preliminary evidence that occupations with greater
coordination intensity are less exposed to displacement by AI, and discuss
opportunities for models that emphasize the collaborative capacities of human
workers, bridge models of crowd work and traditional work, and promote AI in
roles augmenting human collaboration
A Time-varying Shockwave Speed Model for Trajectory Reconstruction using Lagrangian and Eulerian Observations
Inference of detailed vehicle trajectories is crucial for applications such
as traffic flow modeling, energy consumption estimation, and traffic flow
optimization. Static sensors can provide only aggregated information, posing
challenges in reconstructing individual vehicle trajectories. Shockwave theory
is used to reproduce oscillations that occur between sensors. However, as the
emerging of connected vehicles grows, probe data offers significant
opportunities for more precise trajectory reconstruction. Existing methods rely
on Eulerian observations (e.g., data from static sensors) and Lagrangian
observations (e.g., data from probe vehicles) incorporating shockwave theory
and car-following modeling. Despite these advancements, a prevalent issue lies
in the static assignment of shockwave speed, which may not be able to reflect
the traffic oscillations in a short time period caused by varying response
times and vehicle dynamics. Moreover, energy consumption estimation is largely
ignored. In response, this paper proposes a novel framework that integrates
Eulerian and Lagrangian observations for trajectory reconstruction. The
approach introduces a calibration algorithm for time-varying shockwave speed.
The calibrated shockwave speed of the CV is then utilized for trajectory
reconstruction of other non-connected vehicles based on shockwave theory.
Additionaly, vehicle and driver dynamics are introduced to optimize the
trajectory and estimate energy consumption. The proposed method is evaluated
using real-world datasets, demonstrating superior performance in terms of
trajectory accuracy, reproducing traffic oscillations, and estimating energy
consumption
High-Temperature Activated AB2 Nanopowders for Metal Hydride Hydrogen Compression
A reliable process for compressing hydrogen and for removing all contaminants
is that of the metal hydride thermal compression. The use of metal hydride
technology in hydrogen compression applications though, requires thorough
structural characterization of the alloys and investigation of their sorption
properties. The samples have been synthesized by induction - levitation melting
and characterized by Rietveld analysis of the X-Ray diffraction (XRD) patterns.
Volumetric PCI (Pressure-Composition Isotherm) measurements have been conducted
at 20, 60 and 90 oC, in order to investigate the maximum pressure that can be
reached from the selected alloys using water of 90oC. Experimental evidence
shows that the maximum hydrogen uptake is low since all the alloys are
consisted of Laves phases, but it is of minor importance if they have fast
kinetics, given a constant volumetric hydrogen flow. Hysteresis is almost
absent while all the alloys release nearly all the absorbed hydrogen during
desorption. Due to hardware restrictions, the maximum hydrogen pressure for the
measurements was limited at 100 bars. Practically, the maximum pressure that
can be reached from the last alloy is more than 150 bars.Comment: 9 figures. arXiv admin note: text overlap with arXiv:1207.354
Time-to-Green predictions for fully-actuated signal control systems with supervised learning
Recently, efforts have been made to standardize signal phase and timing
(SPaT) messages. These messages contain signal phase timings of all signalized
intersection approaches. This information can thus be used for efficient motion
planning, resulting in more homogeneous traffic flows and uniform speed
profiles. Despite efforts to provide robust predictions for semi-actuated
signal control systems, predicting signal phase timings for fully-actuated
controls remains challenging. This paper proposes a time series prediction
framework using aggregated traffic signal and loop detector data. We utilize
state-of-the-art machine learning models to predict future signal phases'
duration. The performance of a Linear Regression (LR), a Random Forest (RF),
and a Long-Short-Term-Memory (LSTM) neural network are assessed against a naive
baseline model. Results based on an empirical data set from a fully-actuated
signal control system in Zurich, Switzerland, show that machine learning models
outperform conventional prediction methods. Furthermore, tree-based decision
models such as the RF perform best with an accuracy that meets requirements for
practical applications
Antifragile Perimeter Control: Anticipating and Gaining from Disruptions with Reinforcement Learning
The optimal operation of transportation networks is often susceptible to
unexpected disruptions, such as traffic incidents and social events. Many
established control strategies rely on mathematical models that struggle to
cope with real-world uncertainties, leading to a significant decline in
effectiveness when faced with substantial disruptions. While previous research
works have dedicated efforts to improving the robustness or resilience of
transportation systems against disruptions, this paper applies the cutting-edge
concept of antifragility to better design a traffic control strategy for urban
road networks. Antifragility sets itself apart from robustness and resilience
as it represents a system's ability to not only withstand stressors, shocks,
and volatility but also thrive and enhance performance in the presence of such
adversarial events. Hence, modern transportation systems call for solutions
that are antifragile. In this work, we propose a model-free deep Reinforcement
Learning (RL) scheme to control a two-region urban traffic perimeter network.
The system exploits the learning capability of RL under disruptions to achieve
antifragility. By monitoring the change rate and curvature of the traffic state
with the RL framework, the proposed algorithm anticipates imminent disruptions.
An additional term is also integrated into the RL algorithm as redundancy to
improve the performance under disruption scenarios. When compared to a
state-of-the-art model predictive control approach and a state-of-the-art RL
algorithm, our proposed method demonstrates two antifragility-related
properties: (a) gradual performance improvement under disruptions of constant
magnitude; and (b) increasingly superior performance under growing disruptions.Comment: 32 pages, 13 figure
On the Evaluation of the Hyperthermic Efficiency of Magnetic Scaffolds
Goal: Deep-seated tumors (DST) can be treated using thermoseeds exposed to a radiofrequency magnetic field for performing local interstitial hyperthermia treatment (HT). Several research efforts were oriented to the manufacturing of novel biocompatible magnetic nanostructured thermo-seeds, called magnetic scaffolds (MagS). Several iron-doped bioceramics or magnetic polymers in various formulations are available. However, the crucial evaluation of their heating potential has been carried out with significantly different, lab specific, variable experimental conditions and protocols often ignoring the several error sources and inaccuracies estimation. Methods: This work comments and provides a perspective analysis of an experimental protocol for the estimation methodology of the specific absorption rate (SAR) of MagS for DST HT. Numerical multiphysics simultions have been performed to outline the theoretical framework. After the in silico analysis, an experimental case is considered and tested. Results: From the simulations, we found that large overestimation in the SAR values can be found, due to the axial misplacement in the radiofrequency coil, while the radial misplacement has a lower impact on the estimated SAR value. Conclusions: The averaging of multiple temperature records is needed to reliably and effectively estimate the SAR of MagS for DST HT
- …