269 research outputs found
Contrastive Learning of Sentence Embeddings from Scratch
Contrastive learning has been the dominant approach to train state-of-the-art
sentence embeddings. Previous studies have typically learned sentence
embeddings either through the use of human-annotated natural language inference
(NLI) data or via large-scale unlabeled sentences in an unsupervised manner.
However, even in the case of unlabeled data, their acquisition presents
challenges in certain domains due to various reasons. To address these issues,
we present SynCSE, a contrastive learning framework that trains sentence
embeddings with synthesized data. Specifically, we explore utilizing large
language models to synthesize the required data samples for contrastive
learning, including (1) producing positive and negative annotations given
unlabeled sentences (SynCSE-partial), and (2) generating sentences along with
their corresponding annotations from scratch (SynCSE-scratch). Experimental
results on sentence similarity and reranking tasks indicate that both
SynCSE-partial and SynCSE-scratch greatly outperform unsupervised baselines,
and SynCSE-partial even achieves comparable performance to the supervised
models in most settings.Comment: Preprin
System Structure Risk Metric Method Based on Information Flow
Part 5: Modelling and SimulationInternational audienceThe measurement of structure risk aims to analysis and evaluate the not occurred, potential, and the objectively exist risk in system structure. It is an essential way to validate system function and system quality. This paper proposes the risk metric model and algorithm based on information flow and analysis risk trend between traditional tree structure and network-centric structure
A Splicing Approach to Best Subset of Groups Selection
Best subset of groups selection (BSGS) is the process of selecting a small
part of non-overlapping groups to achieve the best interpretability on the
response variable. It has attracted increasing attention and has far-reaching
applications in practice. However, due to the computational intractability of
BSGS in high-dimensional settings, developing efficient algorithms for solving
BSGS remains a research hotspot. In this paper,we propose a group-splicing
algorithm that iteratively detects the relevant groups and excludes the
irrelevant ones. Moreover, coupled with a novel group information criterion, we
develop an adaptive algorithm to determine the optimal model size. Under mild
conditions, it is certifiable that our algorithm can identify the optimal
subset of groups in polynomial time with high probability. Finally, we
demonstrate the efficiency and accuracy of our methods by comparing them with
several state-of-the-art algorithms on both synthetic and real-world datasets.Comment: 49 pages, 7 figure
Correlations between stacked structures and weak itinerant magnetic properties of La Y Ni compounds
Hexagonal LaNi and rhombohedral YNi are weak itinerant
antiferromagnet (wAFM) and ferromagnet (wFM), respectively. The crystal
structure and magnetic properties of intermetallic compounds ( =
La, Y, = Ni) have been investigated combining X-ray powder diffraction and
magnetic measurements. The LaYNi intermetallic compounds with
crystallize in the CeNi-type hexagonal structure
with Y preferentially located in the [] units. The compounds with larger
Y content () crystallize in both hexagonal and rhombohedral
(GdCo-type) structures with a progressive substitution of Y for La in
the sites belonging to the [] units. YNi crystallizes in the
rhombohedral structure only. The average cell volume decreases linearly versus
Y content, whereas the c/a ratio presents a minimum at due to geometric
constrains. The magnetic properties are strongly dependent on the structure
type and the Y content. LaNi displays a complex metamagnetic behavior
with split AFM peaks. Compounds with x = 0.25 and 0.5 display a wAFM ground
state and two metamagnetic transitions, the first one towards an intermediate
wAFM state and the second one towards a FM state.T and the second critical
field increase with the Y content, indicating a stabilization of the AFM state.
LaYNi, which is as the boundary between the two structure types, presents a
very wFM state at low field and an AFM state as the applied field increases.
All the compounds with and containing a rhombohedral phase are wFM with
= 53(2) K. In addition to the experimental studies, first principles
calculations using spin polarization have been performed to interpret the
evolution of both structural phase stability and magnetic ordering for .Comment: 26 pages (7 for supplementary material), 4 tables, 9 main figures and
8 figures in supplementary materia
A SIMPLE Approach to Provably Reconstruct Ising Model with Global Optimality
Reconstruction of interaction network between random events is a critical
problem arising from statistical physics and politics to sociology, biology,
and psychology, and beyond. The Ising model lays the foundation for this
reconstruction process, but finding the underlying Ising model from the least
amount of observed samples in a computationally efficient manner has been
historically challenging for half a century. By using the idea of sparsity
learning, we present a approach named SIMPLE that has a dominant sample
complexity from theoretical limit. Furthermore, a tuning-free algorithm is
developed to give a statistically consistent solution of SIMPLE in polynomial
time with high probability. On extensive benchmarked cases, the SIMPLE approach
provably reconstructs underlying Ising models with global optimality. The
application on the U.S. senators voting in the last six congresses reveals that
both the Republicans and Democrats noticeably assemble in each congresses;
interestingly, the assembling of Democrats is particularly pronounced in the
latest congress
Solid-state Li-ion batteries operating at room temperature using new borohydride argyrodite electrolytes
Using a new class of (BH4)- substituted argyrodite Li6PS5Z0.83(BH4)0.17, (Z =
Cl, I) solid electrolyte, Li-metal solid-state batteries operating at room
temperature have been developed. The cells were made by combining the modified
argyrodite with an In-Li anode and two types of cathode: an oxide, LixMO2 (M =
1/3Ni, 1/3Mn, 1/3Co; so called NMC) and a titanium disulfide, TiS2. The
performance of the cells was evaluated through galvanostatic cycling and
Alternating Current AC electrochemical impedance measurements. Reversible
capacities were observed for both cathodes for at least tens of cycles.
However, the high-voltage oxide cathode cell shows lower reversible capacity
and larger fading upon cycling than the sulfide one. The AC impedance
measurements revealed an increasing interfacial resistance at the cathode side
for the oxide cathode inducing the capacity fading. This resistance was
attributed to the intrinsic poor conductivity of NMC and interfacial reactions
between the oxide material and the argyrodite electrolyte. On the contrary, the
low interfacial resistance of the TiS2 cell during cycling evidences a better
chemical compatibility between this active material and substituted
argyrodites, allowing full cycling of the cathode material, 240 mAhg-1, for at
least 35 cycles with a coulombic efficiency above 97%
- …