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Bin Wu

Publications and source records attributed to Bin Wu.

At least 127 records · Page 7Linked to original sources

DLP: towards active defense against backdoor attacks with decoupled learning process

Deep learning models are well known to be susceptible to backdoor attack, where the attacker only needs to provide a tampered dataset on which the triggers are injected. Models trained on the dataset will passively implant the backdoor, and triggers on the input can mislead the models during testing. Our study shows that the model shows different learning behaviors in clean and poisoned subsets during training. Based on this observation, we propose a general training pipeline to defend against backdoor attacks actively. Benign models can be trained from the unreliable dataset by decoupling the learning process into three stages, i.e., supervised learning, active unlearning, and active semi-supervised fine-tuning. The effectiveness of our approach has been shown in numerous experiments across various backdoor attacks and datasets.

cs.CR↗

NBA: defensive distillation for backdoor removal via neural behavior alignment

Recently, deep neural networks have been shown to be vulnerable to backdoor attacks. A backdoor is inserted into neural networks via this attack paradigm, thus compromising the integrity of the network. As soon as an attacker presents a trigger during the testing phase, the backdoor in the model is activated, allowing the network to make specific wrong predictions. It is extremely important to defend against backdoor attacks since they are very stealthy and dangerous. In this paper, we propose a novel defense mechanism, Neural Behavioral Alignment (NBA), for backdoor removal. NBA optimizes the distillation process in terms of knowledge form and distillation samples to improve defense performance according to the characteristics of backdoor defense. NBA builds high-level representations of neural behavior within networks in order to facilitate the transfer of knowledge. Additionally, NBA crafts pseudo samples to induce student models exhibit backdoor neural behavior. By aligning the backdoor neural behavior from the student network with the benign neural behavior from the teacher network, NBA enables the proactive removal of backdoors. Extensive experiments show that NBA can effectively defend against six different backdoor attacks and outperform five state-of-the-art defenses.

cs.CR↗

Systematic analysis of the form factors of $B_c\rightarrowη_c$, $J/ψ$ and corresponding weak decays

The form factors of $B_c\rightarrowη_c$ and $B_c\rightarrow J/ψ$ are analyzed in the framework of three-point QCD sum rules. In these analyses, the contributions of the vacuum condensate terms $\langle g_{s}^{2}GG\rangle$ and $\langle g_{s}^{3}GGGf\rangle$ are considered. In addition, the decay widths and branching ratios of several decay channels are obtained by using the calculated form factors. These decay processes include the nonleptonic decays of $B_c^- \to η_c π^-$, $η_c K^-$, $η_c ρ^-$, $η_c K^{*-}$, $B_c^- \to J/ψπ^-$, $J/ψK^-$, $J/ψρ^-$, $J/ψK^{*-}$, and the semileptonic decays of $B_c^- \to η_c \mathcal{l} \barν$, $B_c^- \to J/ψ\mathcal{l} \barν$. These results about the form factors and decay properties of $B_c$ meson provide useful information for us to study the heavy-quark dynamics and find new physics(NP) beyond Standard Model(SM).

hep-ph↗

Quark production and thermalization of the quark-gluon plasma

We first assemble a full set of the Boltzmann Equation in Diffusion Approximation (BEDA) for studying thermalization/hydrodynamization as well as the production of massless quarks and antiquarks in out of equilibrium systems. In the BEDA, the time evolution of a generic system is characterized by the following space-time dependent quantities: the jet quenching parameter, the effective temperature, and two more for each quark flavor that describe the conversion between gluons and quarks/antiquarks via the $2\leftrightarrow2$ processes. Out of the latter two quantities, an effective net quark chemical potential is defined, which equals the net quark chemical potential after thermal equilibration. We then study thermalization and the production of three flavors of massless quarks and antiquarks in spatially homogeneous systems initially filled only with gluons. A parametric understanding of thermalization and quark production is obtained for either initially very dense or dilute systems, which are complemented by detailed numerical simulations for intermediate values of initial gluon occupancy $f_0$. For a wide range of $f_0$, the final equilibration time is determined to be about one order of magnitude longer than that in the corresponding pure gluon systems. Moreover, during the final stage of the thermalization process for $f_0\geq 10^{-4}$, gluons are found to thermalize earlier than quarks and antiquarks, undergoing the top-down thermalization.

hep-ph↗

A tale of two emergent games: opinion dynamics in dynamical directed networks

Uni-directional social interactions are ubiquitous in real social networks whereas undirected interactions are intensively studied. We establish a voter model in a dynamical directed network. We analytically obtain the degree distribution of the evolving network at any given time. Furthermore, we find that the average degree is captured by an emergent game. On the other hand, we find that the fate of opinions is captured by another emergent game. Beyond expectation, the two emergent games are typically different due to the unidirectionality of the evolving networks. The Nash equilibrium analysis of the two games facilitates us to give the criterion under which the minority opinion with few disciples initially takes over the population eventually for in-group bias. Our work fosters the understanding of opinion dynamics ranging from methodology to research content.

physics.soc-ph↗

Carleman estimates for space semi-discrete approximations of one-dimensional stochastic parabolic equation and its applications

In this paper, we study discrete Carleman estimates for space semi-discrete approximations of one-dimensional stochastic parabolic equation. As applications of these discrete Carleman estimates, we apply them to study two inverse problems for the spatial semi-discrete stochastic parabolic equations, including a discrete inverse random source problem and a discrete Cauchy problem. We firstly establish two Carleman estimates for a one-dimensional semi-discrete stochastic parabolic equation, one for homogeneous boundary and the other for non-homogeneous boundary. Then we apply these two estimates separately to derive two stability results. The first one is the Lipschitz stability for the discrete inverse random source problem. The second one is the Hölder stability for the discrete Cauchy problem.

math.PR↗

Sagnac-type neutron displacement-noise-free interferometeric gravitational-wave detector

The detection of low-frequency gravitational waves on Earth requires the reduction of displacement noise, which dominates the low-frequency band. One method to cancel test mass displacement noise is a neutron displacement-noise-free interferometer (DFI). This paper proposes a new neutron DFI configuration, a Sagnac-type neutron DFI, which uses a Sagnac interferometer in place of the Mach-Zehnder interferometer. We demonstrate that a sensitivity of the Sagnac-type neutron DFI is higher than that of a conventional neutron DFI with the same interferometer scale. This configuration is particularly significant for neutron DFIs with limited space for construction and limited flux from available neutron sources.

gr-qc↗

Opinion dynamics on biased dynamical networks: beyond rare opinion updating

Opinion dynamics is of paramount importance as it provides insights into the complex dynamics of opinion propagation and social relationship adjustment. It is assumed in most of the previous works that social relationships evolve much faster than opinions. This is not always true in reality. We propose an analytical approximation to study this issue for arbitrary time scales between opinion adjustment and network evolution. To this end, the coefficient of determination in statistics is introduced and a one-dimensional stable manifold is analytically found, i.e., the most likely trajectory. With the aid of the stable manifold, we further obtain the fate of opinions and the consensus time, i.e., fixation probability and fixation time. We find that for in-group bias, the more likely individuals are to adopt the popular opinion, the less likely the majority opinion takes over the population, i.e., conformity inhibits the domination of popular opinions. This counter-intuitive result can be interpreted from a game perspective, in which in-group bias refers to a coordination game and rewiring probability refers to a rescaling of the selection intensity. Our work proposes an efficient approximation method to foster the understanding of opinion dynamics in dynamical networks.

physics.soc-ph↗

AC-EVAL: Evaluating Ancient Chinese Language Understanding in Large Language Models

Given the importance of ancient Chinese in capturing the essence of rich historical and cultural heritage, the rapid advancements in Large Language Models (LLMs) necessitate benchmarks that can effectively evaluate their understanding of ancient contexts. To meet this need, we present AC-EVAL, an innovative benchmark designed to assess the advanced knowledge and reasoning capabilities of LLMs within the context of ancient Chinese. AC-EVAL is structured across three levels of difficulty reflecting different facets of language comprehension: general historical knowledge, short text understanding, and long text comprehension. The benchmark comprises 13 tasks, spanning historical facts, geography, social customs, art, philosophy, classical poetry and prose, providing a comprehensive assessment framework. Our extensive evaluation of top-performing LLMs, tailored for both English and Chinese, reveals a substantial potential for enhancing ancient text comprehension. By highlighting the strengths and weaknesses of LLMs, AC-EVAL aims to promote their development and application forward in the realms of ancient Chinese language education and scholarly research. The AC-EVAL data and evaluation code are available at https://github.com/yuting-wei/AC-EVAL.

cs.CL↗

Analysis of the electromagnetic form factors and the radiative decays of the vector heavy-light mesons

In this article, we analyze the electromagnetic form factors of the vector heavy-light mesons to the pseudoscalar heavy-light mesons in the framework of three-point QCD sum rules, where the contributions of vacuum condensate terms $\langle\overline{q}q\rangle$, $\langle\overline{q}g_{s}σGq\rangle$, $\langle g_{s}^{2}G^{2}\rangle$, $\langle f^{3}G^{3}\rangle$ and $\langle\overline{q}q\rangle\langle g_{s}^{2}G^{2}\rangle$ are considered. With these results, we also obtain the radiative decay widths of the vector heavy-light mesons and then compare our results with those of other collaboration's. The final results about the radiative decay widths are $Γ(D^{*0}\to D^{0}γ)=1.74^{+0.40}_{-0.37}$ keV, $Γ(D^{*+}\to D^{+}γ)=0.17^{+0.08}_{-0.07}$ keV, $Γ(D_{s}^{*}\to D_{s}γ)=0.029^{+0.009}_{-0.008}$ keV, $Γ(B^{*0}\to B^{0}γ)=0.018^{+0.006}_{-0.005}$ keV, $Γ(B^{*+}\to B^{+}γ)=0.015^{+0.007}_{-0.007}$ keV and $Γ(B^{*}_{s}\to B_{s}γ)=0.016^{+0.003}_{-0.005}$ keV.

hep-ph↗

Generalized Maxwell equal area law and black holes in complex free energy

Maxwell equal area law is an important and traditional analytical tool in thermodynamic phase transition, especially in the calculation of gas-liquid phase transition, which reconciles the theoretical calculation with the experimental results. Undoubtedly, its importance is also self-evident for the black hole thermodynamic system. In this study, we construct a generalized Maxwell equal area law, which allows different states of thermodynamic systems to be within the generalized free energy. The black hole thermodynamic characteristics are spontaneously emerged in the free energy landscape. Furthermore, by analytic continuation, we utilize the properties of analytical functions to investigate some universal characteristics of thermodynamic phase transitions in black holes, and preliminarily establish the counterpart of thermodynamic phase transitions in the complex domain.

gr-qc↗

Thermodynamic phase transition rate for the third-order Lovelock black hole in diverse dimensions

The phase transition has always been a major focus in the study of black hole thermodynamics. This study employs the Kramer escape rate from stochastic processes to investigate the first-order phase transition strength between the large and small black hole states. The results indicate that the phase transition of the third-order Lovelock black holes exhibits significant asymmetric characteristics in diverse dimensions both in the hyperbolic and spherical topology, with an overall trend of the transition from large black holes to small black holes. Especially for the spherical topology, when the dimension is higher than seven, there exists a certain temperature beyond which a dynamic equilibrium is established for the phase transition. This study provides valuable insights into the first-order phase transition rate of black holes and enriches the understanding of black hole phase transitions.

gr-qc↗

Precision boson-jet azimuthal decorrelation at hadron colliders

The azimuthal angular decorrelation of a vector boson and jet is sensitive to QCD radiation, and can be used to probe the quark-gluon plasma in heavy-ion collisions. By using a recoil-free jet definition, the sensitivity to contamination from soft radiation on the measurement is reduced, and the complication of non-global logarithms is eliminated from our theoretical calculation. Specifically we will consider the $p_T^n$ recombination scheme, as well as the $n\to \infty$ limit, known as the winner-take-all scheme. These jet definitions also significantly simplify the calculation for a track-based measurement, which is preferred due to its superior angular resolution. We present a detailed discussion of the factorization in Soft-Collinear Effective Theory, revealing why the transverse momentum $\vec q_T$ is more complicated than the azimuthal angle. We show that potential glauber contributions do not spoil our factorization formalism, at least up to and including order $α_s^3$. The resummation is carried out using the renormalization group, and all necessary ingredients are collected or calculated. We conclude with a detailed phenomenological study, finding an enhanced matching correction for high jet $p_T$ due to the electroweak collinear enhancement of a boson emission off di-jets. We also compare with the Pythia event generator, finding that our observable is very robust to hadronization and the underlying event.

hep-ph↗

Thermalization and quark production in spatially homogeneous systems of gluons

We first assemble a full set of the Boltzmann Equation in Diffusion Approximation (BEDA) for studying thermalization/hydrodynamization and quark production in out of equilibrium systems. We then discuss thermalization and the production of three flavors of massless quarks in spatially homogeneous systems initially filled only with gluons. A complete parametric understanding for thermalization and quark production is obtained for both initially very dense or dilute systems, which are complemented by detailed numerical simulations. For initial distributions more relevant for heavy-ion collisions, the complete thermal equilibration is found to be significantly delayed by considering quark production.

hep-ph↗

A robust way to speed up consensus via adaptive social networks

Opinion dynamics is crucial for unraveling the complexities of human interaction in the information age. How to speed up consensus without disturbing the fate of the system is key for opinion dynamics. We propose a voter model on adaptive networks, which resembles the coevolutionary process between opinions and social relationships. We prove the existence of a one-dimensional stable manifold for the system, which facilitates us to study both the fate of the system and the consensus time it takes. Surprisingly, we find the adjustment of social relations speeds up consensus but does not affect the fate of the system. For echo-chamber-like networks which consist of two homogeneous subnetworks connected by few sparse links, a small probability of adaptive edge dynamics is sufficient to accelerate consensus formation, which is counterintuitive. If the network structure makes consensus much slower than that of the regular networks, minor random rewiring makes a discontinuous drop in consensus time. Our work opens up an avenue for speeding up consensus without disturbing the fate of the system. It can be insightful for crowd control.

physics.soc-ph↗

Effects of wave parameters on load reduction performance for amphibious aircraft with V-hydrofoil

An investigation of the influence of the hydrofoil on load reduction performance during an amphibious aircraft landing on still and wavy water is conducted by solving the Unsteady Reynolds-Averaged Navier-Stokes equations coupled with the standard $k-ω$ turbulence model in this paper. During the simulations, the numerical wave tank is realized by using the velocity-inlet boundary wave maker coupled with damping wave elimination technique on the outlet, while the volume of fluid model is employed to track the water-air interface. Subsequently, the effects of geometric parameters of hydrofoil have been first discussed on still water, which indicates the primary factor influencing the load reduction is the static load coefficient of hydrofoil. Furthermore, the effects of descent velocity, wave length and wave height on load reduction are comprehensively investigated. The results show that the vertical load reduces more than 55$\%$ at the early stage of landing on the still water through assembling the hydrofoil for different descent velocity cases. Meanwhile, for the amphibious aircraft with high forward velocity, the bottom of the fuselage will come into close contact with the first wave when landing on crest position, and then the forebody will impact the next wave surface with extreme force. In this circumstance, the load reduction rate decreases to around 30$\%$, which will entail a further decline with the increase of wave length or wave height.

physics.flu-dyn↗

Optimization of quantum noise in space gravitational-wave antenna DECIGO with optical-spring quantum locking considering mixture of vacuum fluctuations in homodyne detection

Quantum locking using optical spring and homodyne detection has been devised to reduce quantum noise that limits the sensitivity of DECIGO, a space-based gravitational wave antenna in the frequency band around 0.1 Hz for detection of primordial gravitational waves. The reduction in the upper limit of energy density $Ω_{\mathrm{GW}}$ from $2{\times}10^{-15}$ to $1{\times}10^{-16}$, as inferred from recent observations, necessitates improved sensitivity in DECIGO to meet its primary science goals. To accurately evaluate the effectiveness of this method, this paper considers a detection mechanism that takes into account the influence of vacuum fluctuations on homodyne detection. In addition, an advanced signal processing method is devised to efficiently utilize signals from each photodetector, and design parameters for this configuration are optimized for the quantum noise. Our results show that this method is effective in reducing quantum noise, despite the detrimental impact of vacuum fluctuations on its sensitivity.

gr-qc↗

Query-aware Long Video Localization and Relation Discrimination for Deep Video Understanding

The surge in video and social media content underscores the need for a deeper understanding of multimedia data. Most of the existing mature video understanding techniques perform well with short formats and content that requires only shallow understanding, but do not perform well with long format videos that require deep understanding and reasoning. Deep Video Understanding (DVU) Challenge aims to push the boundaries of multimodal extraction, fusion, and analytics to address the problem of holistically analyzing long videos and extract useful knowledge to solve different types of queries. This paper introduces a query-aware method for long video localization and relation discrimination, leveraging an imagelanguage pretrained model. This model adeptly selects frames pertinent to queries, obviating the need for a complete movie-level knowledge graph. Our approach achieved first and fourth positions for two groups of movie-level queries. Sufficient experiments and final rankings demonstrate its effectiveness and robustness.

cs.CV↗