216 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
Orientation-Dependent Atomic-Scale Mechanism of - Thin Film Epitaxial Growth
- has gained intensive interests of
research and application as an ultrawide bandgap semiconductor. Epitaxial
growth technique of the - thin film
possesses a fundamental and vital role in the
-based device fabrication. In this work,
epitaxial growth mechanisms of - with
four low Miller-index facets, namely (100), (010), (001), and
(01), are systematically explored using large-scale
machine-learning molecular dynamics simulations at the atomic scale. The
simulations reveal that the migration of the face-centered cubic stacking O
sublattice plays a predominant role in rationalizing the different growth
mechanisms between (100)/(010)/(001) and (01) orientations. The
resultant complex combinations of the stacking faults and twin boundaries are
carefully identified, and shows a good agreement with the experimental
observation and ab initio calculation. Our results provide useful insights into
the gas-phase epitaxial growth of the -
thin films and suggest possible ways to tailor its properties for specific
applications.Comment: 6 pages, 5 figures, under peer revie
Experimental Study on Piezoelectric Energy Harvesting from Vortex-Induced Vibrations and Wake-Induced Vibrations
Piezoelectric Wind Energy Harvesting from Self-Excited Vibration of Square Cylinder
Self-excited vibration of a square cylinder has been considered as an effective way in harvesting piezoelectric wind energy. In present work, both of the vortex-induced vibration and unstable galloping phenomenon process are investigated in a reduced velocity (Ur=U/ΟnΒ·D) range of 4β€Urβ€20 with load resistance ranging in 100βΞ©β€Rβ€1βMΞ©. The vortex-induced vibration covers presynchronization, synchronization, and postsynchronization branches. An aeroelectromechanical model is given to describe the coupling of the dynamic equation of the fluid-structure interaction and the equation of Gauss law. The effects of load resistance are investigated in both the open-circuit and close-circuit system by a linear analysis, which covers the parameters of the transverse displacement, aerodynamic force, output voltage, and harvested power utilized to measure the efficiency of the system. The highest level of the transverse displacement and the maximum value of harvested power of synchronization branch during the vortex-induced vibration and galloping are obtained. The results show that the large-amplitude galloping at high wind speeds can generate energy. Additionally, energy can be harvested by utilization of the lock-in phenomenon of vortex-induced vibration under low wind speed
High-order gas-kinetic scheme with TENO class reconstruction for the Euler and Navier-Stokes equations
The high-order gas-kinetic scheme(HGKS) with WENO spatial reconstruction
method has been extensively validated through many numerical experiments,
demonstrating its superior accuracy efficiency, and robustness. Compared with
WENO class schemes, TENO class schemes exhibit significantly improved
robustness, low numerical dissipation and sharp discontinuity capturing. In
this paper, two kinds of fifth-order HGKS with TENO class schemes are designed.
One involves replacing WENO5 scheme with the TENO5 scheme in the conventional
WENO5-GKS. WENO and TENO schemes only provide the non-equilibrium state values
at the cell interface. The slopes of the non-equilibrium state along with the
equilibrium values and slopes, are obtained by additional linear
reconstruction. Another kind of TENO5-D GKS is similar to WENO5-AO GKS.
Following a strong scale-separation procedure, a tailored novel ENO-like
stencil selection strategy is proposed such that the high-order accuracy is
restored in smooth regions by selecting the candidate reconstruction on the
large stencil while the ENO property is enforced near discontinuities by
adopting the candidate reconstruction from smooth small stencils. The such TENO
schemes are TENO-AA and TENO-D scheme. The HGKS scheme based on WENO-AO or
TENO-D reconstruction take advantage of the large stencil to provide point
values and slopes of the non-equilibrium state. By dynamically merging the
reconstructed non-equilibrium slopes, extra reconstruction of the equilibrium
state at the beginning of each time step can be avoided. The simplified schemes
have better robustness and efficiency than the conventional WENO5-GKS or
TENO5-GKS. TENO-D GKS is also as easy to develop as WENO-AO GKS to high-order
finite volume method for unstructured mesh.Comment: arXiv admin note: text overlap with arXiv:2304.05572; text overlap
with arXiv:1905.08489 by other author
Study on Fluid-Induced Vibration Power Harvesting of Square Columns under Different Attack Angles
A model of the flow-vibration-electrical circuit multiphysical coupling system for solving square column vortex-induced vibration piezoelectric energy harvesting (VIVPEH) is proposed in this paper. The quasi steady state theory is adopted to describe the fluid solid coupling process of vortex-induced vibration based on the finite volume method coupled Gauss equation. The vibrational response and the quasi steady state form of the output voltage are solved by means of the matrix coefficient method and interactive computing. The results show that attack angles play an important role in the performance of square column VIVPEH, of which Ξ±=45Β° is a relatively ideal attack angle of square column VIVPEH
Energy Harvester Based on the Synchronization Phenomenon of a Circular Cylinder
A concept of generating power from a circular cylinder undergoing vortex-induced vibration (VIV) was investigated. Two lead zirconate titanate (PZT) beams which had high power density were installed on the cylinder. A theoretical model has been presented to describe the electromechanical coupling of the open-circuit voltage output and the vibration amplitudes based on a second-order nonlinear Van der pol equation and Gauss law. A numerical computation was applied to measure the capacity of the power generating system. The lift and drag coefficient and the vortex shedding frequency were obtained to verify how the nondimensional parameter reduced velocity Ur affects the fluid field. Meanwhile, a single-degree of freedom system has been added to describe the VIV, presynchronization, and synchronization together with postsynchronization regimes of oscillating frequencies. And the amplitudes of the vibration have been obtained. Finally, the vibrational amplitudes and the voltage output could go up to a high level in the synchronization region. The maximum value of the voltage output and the corresponding reduced velocity Ur were 8.42βV and 5.6, respectively
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Slc39a7/zip7 Plays a Critical Role in Development and Zinc Homeostasis in Zebrafish
Background: Slc39a7/Zip7, also known as Ke4, is a member of solute carrier family 39 (Slc39a) and plays a critical role in regulating cell growth and death. Because the function of Zip7 in vivo was unclear, the present study investigated the function of zip7 in vertebrate development and zinc metabolism using zebrafish as a model organism. Principal Finding: Using real-time PCR to determine the gene expression pattern of zip7 during zebrafish development, we found that zip7 mRNA is expressed throughout embryonic development and into maturity. Interestingly, whole mount in situ hybridization revealed that while zip7 mRNA is ubiquitously expressed until 12 hours post-fertilization (hpf); at 24 hpf and beyond, zip7 mRNA was specifically detected only in eyes. Morpholino-antisense (MO) gene knockdown assay revealed that downregulation of zip7 expression resulted in several morphological defects in zebrafish including decreased head size, smaller eyes, shorter palates, and shorter and curved spinal cords. Analysis by synchrotron radiation X-ray fluorescence (SR-XRF) showed reduced concentrations of zinc in brain, eyes, and gills of zip7-MO-injected embryos. Furthermore, incubation of the zip7 knockdown embryos in a zinc-supplemented solution was able to rescue the MO-induced morphological defects. Significance: Our data suggest that zip7 is required for eye, brain, and skeleton formation during early embryonic development in zebrafish. Moreover, zinc supplementation can partially rescue defects resulting from zip7 gene knockdown. Taken together, our data provide critical insight into a novel function of zip7 in development and zinc homeostasis in vivo in zebrafish
PsyBench: a balanced and in-depth Psychological Chinese Evaluation Benchmark for Foundation Models
As Large Language Models (LLMs) are becoming prevalent in various fields,
there is an urgent need for improved NLP benchmarks that encompass all the
necessary knowledge of individual discipline. Many contemporary benchmarks for
foundational models emphasize a broad range of subjects but often fall short in
presenting all the critical subjects and encompassing necessary professional
knowledge of them. This shortfall has led to skewed results, given that LLMs
exhibit varying performance across different subjects and knowledge areas. To
address this issue, we present psybench, the first comprehensive Chinese
evaluation suite that covers all the necessary knowledge required for graduate
entrance exams. psybench offers a deep evaluation of a model's strengths and
weaknesses in psychology through multiple-choice questions. Our findings show
significant differences in performance across different sections of a subject,
highlighting the risk of skewed results when the knowledge in test sets is not
balanced. Notably, only the ChatGPT model reaches an average accuracy above
, indicating that there is still plenty of room for improvement. We
expect that psybench will help to conduct thorough evaluations of base models'
strengths and weaknesses and assist in practical application in the field of
psychology
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