190 research outputs found
WordSup: Exploiting Word Annotations for Character based Text Detection
Imagery texts are usually organized as a hierarchy of several visual
elements, i.e. characters, words, text lines and text blocks. Among these
elements, character is the most basic one for various languages such as
Western, Chinese, Japanese, mathematical expression and etc. It is natural and
convenient to construct a common text detection engine based on character
detectors. However, training character detectors requires a vast of location
annotated characters, which are expensive to obtain. Actually, the existing
real text datasets are mostly annotated in word or line level. To remedy this
dilemma, we propose a weakly supervised framework that can utilize word
annotations, either in tight quadrangles or the more loose bounding boxes, for
character detector training. When applied in scene text detection, we are thus
able to train a robust character detector by exploiting word annotations in the
rich large-scale real scene text datasets, e.g. ICDAR15 and COCO-text. The
character detector acts as a key role in the pipeline of our text detection
engine. It achieves the state-of-the-art performance on several challenging
scene text detection benchmarks. We also demonstrate the flexibility of our
pipeline by various scenarios, including deformed text detection and math
expression recognition.Comment: 2017 International Conference on Computer Visio
Zero-Resource Hallucination Prevention for Large Language Models
The prevalent use of large language models (LLMs) in various domains has
drawn attention to the issue of "hallucination," which refers to instances
where LLMs generate factually inaccurate or ungrounded information. Existing
techniques for hallucination detection in language assistants rely on intricate
fuzzy, specific free-language-based chain of thought (CoT) techniques or
parameter-based methods that suffer from interpretability issues. Additionally,
the methods that identify hallucinations post-generation could not prevent
their occurrence and suffer from inconsistent performance due to the influence
of the instruction format and model style. In this paper, we introduce a novel
pre-detection self-evaluation technique, referred to as {\method}, which
focuses on evaluating the model's familiarity with the concepts present in the
input instruction and withholding the generation of response in case of
unfamiliar concepts. This approach emulates the human ability to refrain from
responding to unfamiliar topics, thus reducing hallucinations. We validate
{\method} across four different large language models, demonstrating
consistently superior performance compared to existing techniques. Our findings
propose a significant shift towards preemptive strategies for hallucination
mitigation in LLM assistants, promising improvements in reliability,
applicability, and interpretability
Pore-scale study of miscible density instability with viscosity contrast in porous media
The transport of miscible fluids in porous media is a prevalent phenomenon that occurs in various natural and industrial contexts. However, this fundamental phenomenon is usually coupled with interface instabilities (e.g., viscous/density fingering), which has yet to be thoroughly investigated. In this paper, a multiple-relaxation-time lattice Boltzmann method is applied to study the displacement between two miscible fluids in porous media at the pore scale, with the coexistence of density difference (Rayleigh number Ra), viscosity contrast (R), and injection velocity (Utop). A parametric study is conducted to evaluate the impact of Ra, R, and Utop on the flow stability. For a fixed Ra that can trigger density fingering, the increase in R or Utop is found to suppress density fingering. Consequently, under a large Utop and a moderate R, the density fingering is fully stabilized and the flow follows a stabile pattern. Furthermore, as both R and Utop grow to a sufficiently high level, they can jointly trigger viscous fingering. In addition, the increasing Ra shows an enhancing effect on both density fingering and viscous fingering. Finally, by quantitatively analyzing the fingering length (lm) and the fingering propagation time (te), five different flow patterns are classified as viscosity-suppressed (I), viscosity-enhanced (II), viscosity-unstable (III), displacement-suppressed (IV), and stable (V) regimes. In a three-dimensional parameter space spanned by Ra, R, and Utop, the parameter ranges of the five regimes are determined according to lm and te. These findings hold a significant value in providing guidance for controlling the flow stability by selecting appropriate operating conditions
Symmetric Pruning in Quantum Neural Networks
Many fundamental properties of a quantum system are captured by its
Hamiltonian and ground state. Despite the significance of ground states
preparation (GSP), this task is classically intractable for large-scale
Hamiltonians. Quantum neural networks (QNNs), which exert the power of modern
quantum machines, have emerged as a leading protocol to conquer this issue. As
such, how to enhance the performance of QNNs becomes a crucial topic in GSP.
Empirical evidence showed that QNNs with handcraft symmetric ansatzes generally
experience better trainability than those with asymmetric ansatzes, while
theoretical explanations have not been explored. To fill this knowledge gap,
here we propose the effective quantum neural tangent kernel (EQNTK) and connect
this concept with over-parameterization theory to quantify the convergence of
QNNs towards the global optima. We uncover that the advance of symmetric
ansatzes attributes to their large EQNTK value with low effective dimension,
which requests few parameters and quantum circuit depth to reach the
over-parameterization regime permitting a benign loss landscape and fast
convergence. Guided by EQNTK, we further devise a symmetric pruning (SP) scheme
to automatically tailor a symmetric ansatz from an over-parameterized and
asymmetric one to greatly improve the performance of QNNs when the explicit
symmetry information of Hamiltonian is unavailable. Extensive numerical
simulations are conducted to validate the analytical results of EQNTK and the
effectiveness of SP.Comment: Accepted to International Conference on Learning Representations
(ICLR) 202
Lattice Boltzmann modelling of salt precipitation during brine evaporation
Salt precipitation during brine evaporation in porous media is an important phenomenon in a variety of natural and engineering scenarios. This work establishes a multiphase multicomponent lattice Boltzmann (LB) method with phase change for simulating salt precipitation during brine evaporation. In the proposed LB models, the gas–brine multiphase flow, brine evaporation, salt concentration evolution, salt precipitate nucleation and growth are simultaneously considered. Simulations of the Stefan problem are first conducted to verify the proposed numerical models and determine the diffusion coefficient of brine vapour. Once the lattice Boltzmann models have been validated, salt precipitation during brine evaporation is simulated to investigate the competition mechanisms between salt precipitate nucleation and growth reaction. The results show that the typical salt precipitation patterns in existing experimental observation can be successfully reproduced, including the ring-like and pancake-like patterns. The difference in the salt precipitation patterns is explained by the competition mechanism between precipitate growth and nucleation according to the present study. Furthermore, the salt precipitation during gas injection into a microfluidic chip is investigated. The evolution of salt and brine saturation shows similar patterns to existing experimental results, and the effects of the gas injection rate on salt precipitation performance are clarified. The LB models in the present work can simulate salt precipitation with comprehensive consideration of multiphase brine evaporation, salt species mass transport, precipitate nucleation and growth, which have not been realized in previous studies. The numerical showcases demonstrate the excellent performance of the proposed models for the simulation of salt precipitation in porous media, which promise to guide practical engineering applications like CO2 sequestration
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