7,962 research outputs found
Reducing climate risk in energy system planning: a posteriori time series aggregation for models with storage
The growth in variable renewables such as solar and wind is increasing the impact of climate uncertainty in energy system planning. Addressing this ideally requires high-resolution time series spanning at least a few decades. However, solving capacity expansion planning models across such datasets often requires too much computing time or memory.
To reduce computational cost, users often employ time series aggregation to compress demand and weather time series into a smaller number of time steps. Methods are usually a priori, employing information about the input time series only. Recent studies highlight the limitations of this approach, since reducing statistical error metrics on input time series does not in general lead to more accurate model outputs. Furthermore, many aggregation schemes are unsuitable for models with storage since they distort chronology.
In this paper, we introduce a posteriori time series aggregation schemes that preserve chronology and hence allow modelling of storage technologies. Our methods adapt to the underlying energy system model; aggregation may differ in systems with different technologies or topologies even with the same time series inputs. They do this by using operational variables (generation, transmission and storage patterns) in addition to time series inputs when aggregating.
We investigate a number of approaches. We find that a posteriori methods can perform better than a priori ones, primarily through a systematic identification and preservation of relevant extreme events. We hope that these tools render long demand and weather time series more manageable in capacity expansion planning studies. We make our models, data, and code publicly available
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
Relatedly: Scaffolding Literature Reviews with Existing Related Work Sections
Scholars who want to research a scientific topic must take time to read,
extract meaning, and identify connections across many papers. As scientific
literature grows, this becomes increasingly challenging. Meanwhile, authors
summarize prior research in papers' related work sections, though this is
scoped to support a single paper. A formative study found that while reading
multiple related work paragraphs helps overview a topic, it is hard to navigate
overlapping and diverging references and research foci. In this work, we design
a system, Relatedly, that scaffolds exploring and reading multiple related work
paragraphs on a topic, with features including dynamic re-ranking and
highlighting to spotlight unexplored dissimilar information, auto-generated
descriptive paragraph headings, and low-lighting of redundant information. From
a within-subjects user study (n=15), we found that scholars generate more
coherent, insightful, and comprehensive topic outlines using Relatedly compared
to a baseline paper list
High-speed running quadruped robot with a multi-joint spine adopting a 1DoF closed-loop linkage
Improving the mobility of robots is an important goal for many real-world applications and implementing an animal-like spine structure in a quadruped robot is a promising approach to achieving high-speed running. This paper proposes a feline-like multi-joint spine adopting a one-degree-of-freedom closed-loop linkage for a quadruped robot to realize high-speed running. We theoretically prove that the proposed spine structure can realize 1.5 times the horizontal range of foot motion compared to a spine structure with a single joint. Experimental results demonstrate that a robot with the proposed spine structure achieves 1.4 times the horizontal range of motion and 1.9 times the speed of a robot with a single-joint spine structure
TraVaG: Differentially Private Trace Variant Generation Using GANs
Process mining is rapidly growing in the industry. Consequently, privacy
concerns regarding sensitive and private information included in event data,
used by process mining algorithms, are becoming increasingly relevant.
State-of-the-art research mainly focuses on providing privacy guarantees, e.g.,
differential privacy, for trace variants that are used by the main process
mining techniques, e.g., process discovery. However, privacy preservation
techniques for releasing trace variants still do not fulfill all the
requirements of industry-scale usage. Moreover, providing privacy guarantees
when there exists a high rate of infrequent trace variants is still a
challenge. In this paper, we introduce TraVaG as a new approach for releasing
differentially private trace variants based on \text{Generative Adversarial
Networks} (GANs) that provides industry-scale benefits and enhances the level
of privacy guarantees when there exists a high ratio of infrequent variants.
Moreover, TraVaG overcomes shortcomings of conventional privacy preservation
techniques such as bounding the length of variants and introducing fake
variants. Experimental results on real-life event data show that our approach
outperforms state-of-the-art techniques in terms of privacy guarantees, plain
data utility preservation, and result utility preservation
Initial Fulcher band observations from high resolution spectroscopy in the MAST-U divertor
High resolution Fulcher band spectroscopy was used in the MAST-U divertors
during Super-X and elongated conventional divertor density ramps with
fuelling from the mid-plane high-field side. In the Super-X case
(density ramp from Greenwald fraction 0.12 to 0.24), the upper divertor showed
ground state rotational temperatures of the molecules increasing
from 6000 K, starting at the detachment onset, to 9000 K during
deepening detachment. This was correlated with the movement of the Fulcher
emission region, which is correlated with the ionisation source. The increase
in rotational temperature did not occur near the divertor entrance, where the
plasma was still ionising. Qualitative agreement was obtained between the lower
and upper divertor. Similar rotational temperatures were obtained in the
elongated divertor before the detachment onset, although the increase in
rotational temperature during detachment was less clearly observed as less deep
detachment was obtained. %In the elongated conventional divertor there was some
qualitative agreement of this effect impeded by low signal.
The measured vibrational distribution of the upper Fulcher state (first four
bands) does not agree with a ground state Boltzmann distribution but shows a
different characteristic with an elevated population especially in the and bands. The populations of the and band
relative to the band are roughly proportional to the
temperature
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Innovation in Energy Security and Long-Term Energy Efficiency â…¡
The sustainable development of our planet depends on the use of energy. The increasing world population inevitably causes an increase in the demand for energy, which, on the one hand, threatens us with the potential to encounter a shortage of energy supply, and, on the other hand, causes the deterioration of the environment. Therefore, our task is to reduce this demand through different innovative solutions (i.e., both technological and social). Social marketing and economic policies can also play their role by affecting the behavior of households and companies and by causing behavioral change oriented to energy stewardship, with an overall switch to renewable energy resources. This reprint provides a platform for the exchange of a wide range of ideas, which, ultimately, would facilitate driving societies toward long-term energy efficiency
Assembling Single RbCs Molecules with Optical Tweezers
Optical tweezer arrays are useful tools for manipulating single atoms and molecules.
An exciting avenue for research with optical tweezers is using the interactions between polar molecules for quantum computation or quantum simulation.
Molecules can be assembled in an optical tweezer array starting from pairs of atoms.
The atoms must be initialised in the relative motional ground state of a common trap.
This work outlines the design of a Raman sideband cooling protocol which is implemented to prepare an 87-Rubidium atom in the motional ground state of an 817 nm tweezer, and a 133-Caesium atom in the motional ground state of a 938 nm tweezer.
The protocol circumvents strong heating and dephasing associated with the trap by operating at lower trap depths and cooling from outside the Lamb-Dicke regime.
By analysing several sources of heating, we design and implement a merging sequence that transfers the Rb atom and the Cs atom to a common trap with minimal motional excitation.
Subsequently, we perform a detailed characterisation of AC Stark shifts caused by the tweezer light, and identify several situations in which the confinement of the atom pair influences their interactions.
Then, we demonstrate the preparation of a molecular bound state after an adiabatic ramp across a magnetic Feshbach resonance.
Measurements of molecular loss rates provide evidence that the atoms are in fact associated during the merging sequence, before the magnetic field ramp.
By preparing a weakly-bound molecule in an optical tweezer, we carry out important steps towards assembling an array of ultracold RbCs molecules in their rovibrational ground states
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