70 research outputs found
Efficient Climate Simulation via Machine Learning Method
Hybrid modeling combining data-driven techniques and numerical methods is an
emerging and promising research direction for efficient climate simulation.
However, previous works lack practical platforms, making developing hybrid
modeling a challenging programming problem. Furthermore, the lack of standard
data sets and evaluation metrics may hamper researchers from comprehensively
comparing various algorithms under a uniform condition. To address these
problems, we propose a framework called NeuroClim for hybrid modeling under the
real-world scenario, a basic setting to simulate the real climate that we live
in. NeuroClim consists of three parts: (1) Platform. We develop a user-friendly
platform NeuroGCM for efficiently developing hybrid modeling in climate
simulation. (2) Dataset. We provide an open-source dataset for data-driven
methods in hybrid modeling. We investigate the characteristics of the data,
i.e., heterogeneity and stiffness, which reveals the difficulty of regressing
climate simulation data; (3) Metrics. We propose a methodology for
quantitatively evaluating hybrid modeling, including the approximation ability
of machine learning models and the stability during simulation. We believe that
NeuroClim allows researchers to work without high level of climate-related
expertise and focus only on machine learning algorithm design, which will
accelerate hybrid modeling research in the AI-Climate intersection. The codes
and data are released at https://github.com/x-w19/NeuroClim.Comment: Work in progres
A Framework for Designing Fair Ubiquitous Computing Systems
Over the past few decades, ubiquitous sensors and systems have been an
integral part of humans' everyday life. They augment human capabilities and
provide personalized experiences across diverse contexts such as healthcare,
education, and transportation. However, the widespread adoption of ubiquitous
computing has also brought forth concerns regarding fairness and equitable
treatment. As these systems can make automated decisions that impact
individuals, it is essential to ensure that they do not perpetuate biases or
discriminate against specific groups. While fairness in ubiquitous computing
has been an acknowledged concern since the 1990s, it remains understudied
within the field. To bridge this gap, we propose a framework that incorporates
fairness considerations into system design, including prioritizing stakeholder
perspectives, inclusive data collection, fairness-aware algorithms, appropriate
evaluation criteria, enhancing human engagement while addressing privacy
concerns, and interactive improvement and regular monitoring. Our framework
aims to guide the development of fair and unbiased ubiquitous computing
systems, ensuring equal treatment and positive societal impact.Comment: 8 pages, 1 figure, published in 2023 ACM International Joint
Conference on Pervasive and Ubiquitous Computing & the 2023 ACM International
Symposium on Wearable Computin
Benchmarking Generation and Evaluation Capabilities of Large Language Models for Instruction Controllable Summarization
While large language models (LLMs) already achieve strong performance on
standard generic summarization benchmarks, their performance on more complex
summarization task settings is less studied. Therefore, we benchmark LLMs on
instruction controllable text summarization, where the model input consists of
both a source article and a natural language requirement for the desired
summary characteristics. To this end, we curate an evaluation-only dataset for
this task setting and conduct human evaluation on 5 LLM-based summarization
systems. We then benchmark LLM-based automatic evaluation for this task with 4
different evaluation protocols and 11 LLMs, resulting in 40 evaluation methods
in total. Our study reveals that instruction controllable text summarization
remains a challenging task for LLMs, since (1) all LLMs evaluated still make
factual and other types of errors in their summaries; (2) all LLM-based
evaluation methods cannot achieve a strong alignment with human annotators when
judging the quality of candidate summaries; (3) different LLMs show large
performance gaps in summary generation and evaluation. We make our collected
benchmark, InstruSum, publicly available to facilitate future research in this
direction.Comment: GitHub Repo: https://github.com/yale-nlp/InstruSu
Functional group differentiation of isomeric solvents enables distinct zinc anode chemistry
Electrolytes hold the key to realizing reliable zinc (Zn) anodes. Divergent organic molecules have been proven effective in stabilizing Zn anodes; however, irrational comparisons exist due to the uncontrolled molecular weights and functional group amounts. In this work, two “isomeric molecules”: 1,2-dimethoxyethane (DME) and 1-methoxy-2-propanol (PM), with identical molecular weights but different functional groups, have been studied as co-solvents in electrolytes, which have delivered distinct electrochemical performance. Experimental and simulative study indicates the dipole moment induced by the hydroxyl groups in PM (higher molecular polarity than ether groups in DME) reconstructs the space charge region, enhances the concentration of Zn2+ in the vicinity of Zn anodes, and in-situ derives different solid electrolyte interphase (SEI) models and electrode–electrolyte interfaces, resulting in exceptional cycling stability. Remarkably, the Zn||Cu cell with PM worked over 2000 cycles with high Coulombic efficiency (CE) of 99.7%. The Zn||Zn symmetric cell cycled over 2000 h at 1 mA·cm−2, and showed excellent stability at an ultrahigh current density of 10 mA·cm−2 and capacity of 20 mAh·cm−2 over 200 h (depth of discharge, DOD of 70%). The Zn||sodium vanadate pouch cell with a high mass loading of 6.3 mg·cm−2 and a high capacity of 24 mAh demonstrates superior cyclability after 570 h. This work can be a good starting point to provide reliable guidance on electrolyte design for practical aqueous Zn batteries
The Atacama Cosmology Telescope: Mitigating the impact of extragalactic foregrounds for the DR6 CMB lensing analysis
We investigate the impact and mitigation of extragalactic foregrounds for the
CMB lensing power spectrum analysis of Atacama Cosmology Telescope (ACT) data
release 6 (DR6) data. Two independent microwave sky simulations are used to
test a range of mitigation strategies. We demonstrate that finding and then
subtracting point sources, finding and then subtracting models of clusters, and
using a profile bias-hardened lensing estimator, together reduce the fractional
biases to well below statistical uncertainties, with the inferred lensing
amplitude, , biased by less than . We also show
that another method where a model for the cosmic infrared background (CIB)
contribution is deprojected and high frequency data from Planck is included has
similar performance. Other frequency-cleaned options do not perform as well,
incurring either a large noise cost, or resulting in biased recovery of the
lensing spectrum. In addition to these simulation-based tests, we also present
null tests performed on the ACT DR6 data which test for sensitivity of our
lensing spectrum estimation to differences in foreground levels between the two
ACT frequencies used, while nulling the CMB lensing signal. These tests pass
whether the nulling is performed at the map or bandpower level. The
CIB-deprojected measurement performed on the DR6 data is consistent with our
baseline measurement, implying contamination from the CIB is unlikely to
significantly bias the DR6 lensing spectrum. This collection of tests gives
confidence that the ACT DR6 lensing measurements and cosmological constraints
presented in companion papers to this work are robust to extragalactic
foregrounds.Comment: Companion paper to Qu et al and Madhavacheril et a
Atacama Cosmology Telescope: Weighing Distant Clusters with the Most Ancient Light
We use gravitational lensing of the cosmic microwave background (CMB) to measure the mass of the most distant blindly selected sample of galaxy clusters on which a lensing measurement has been performed to date. In CMB data from the the Atacama Cosmology Telescope and the Planck satellite, we detect the stacked lensing effect from 677 near-infrared-selected galaxy clusters from the Massive and Distant Clusters of WISE Survey (MaDCoWS), which have a mean redshift of ⟨z⟩ = 1.08. There are currently no representative optical weak lensing measurements of clusters that match the distance and average mass of this sample. We detect the lensing signal with a significance of 4.2σ. We model the signal with a halo model framework to find the mean mass of the population from which these clusters are drawn. Assuming that the clusters follow Navarro–Frenk–White (NFW) density profiles, we infer a mean mass of ⟨M_(500c)⟩ = (1.7±0.4)×10¹⁴M⊙. We consider systematic uncertainties from cluster redshift errors, centering errors, and the shape of the NFW profile. These are all smaller than 30% of our reported uncertainty. This work highlights the potential of CMB lensing to enable cosmological constraints from the abundance of distant clusters populating ever larger volumes of the observable universe, beyond the capabilities of optical weak lensing measurements
The Atacama Cosmology Telescope: Combined kinematic and thermal Sunyaev-Zel'dovich measurements from BOSS CMASS and LOWZ halos
The scattering of cosmic microwave background (CMB) photons off the
free-electron gas in galaxies and clusters leaves detectable imprints on high
resolution CMB maps: the thermal and kinematic Sunyaev-Zel'dovich effects (tSZ
and kSZ respectively). We use combined microwave maps from the Atacama
Cosmology Telescope (ACT) DR5 and Planck in combination with the CMASS and LOWZ
galaxy catalogs from the Baryon Oscillation Spectroscopic Survey (BOSS DR10 and
DR12), to study the gas associated with these galaxy groups. Using individual
reconstructed velocities, we perform a stacking analysis and reject the no-kSZ
hypothesis at 6.5, the highest significance to date. This directly
translates into a measurement of the electron number density profile, and thus
of the gas density profile. Despite the limited signal to noise, the
measurement shows at high significance that the gas density profile is more
extended than the dark matter density profile, for any reasonable baryon
abundance (formally for the cosmic baryon abundance). We
simultaneously measure the tSZ signal, i.e. the electron thermal pressure
profile of the same CMASS objects, and reject the no-tSZ hypothesis at
10. We combine tSZ and kSZ measurements to estimate the electron
temperature to 20% precision in several aperture bins, and find it comparable
to the virial temperature. In a companion paper, we analyze these measurements
to constrain the gas thermodynamics and the properties of feedback inside
galaxy groups. We present the corresponding LOWZ measurements in this paper,
ruling out a null kSZ (tSZ) signal at 2.9 (13.9), and leave their
interpretation to future work. Our stacking software ThumbStack is publicly
available at https://github.com/EmmanuelSchaan/ThumbStack and directly
applicable to future Simons Observatory and CMB-S4 data.Comment: Accepted in Physical Review D, Editors' Suggestio
The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and its Implications for Structure Growth
We present new measurements of cosmic microwave background (CMB) lensing over
sq. deg. of the sky. These lensing measurements are derived from the
Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB dataset, which
consists of five seasons of ACT CMB temperature and polarization observations.
We determine the amplitude of the CMB lensing power spectrum at
precision ( significance) using a novel pipeline that minimizes
sensitivity to foregrounds and to noise properties. To ensure our results are
robust, we analyze an extensive set of null tests, consistency tests, and
systematic error estimates and employ a blinded analysis framework. The
baseline spectrum is well fit by a lensing amplitude of
relative to the Planck 2018 CMB power spectra
best-fit CDM model and relative to
the best-fit model. From our lensing power
spectrum measurement, we derive constraints on the parameter combination
of
from ACT DR6 CMB lensing alone and
when combining ACT DR6 and Planck NPIPE
CMB lensing power spectra. These results are in excellent agreement with
CDM model constraints from Planck or
CMB power spectrum measurements. Our lensing measurements from redshifts
-- are thus fully consistent with CDM structure growth
predictions based on CMB anisotropies probing primarily . We find no
evidence for a suppression of the amplitude of cosmic structure at low
redshiftsComment: 45+21 pages, 50 figures. Prepared for submission to ApJ. Also see
companion papers Madhavacheril et al and MacCrann et a
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