arXiv subjects

Haijun Yang

Publications and source records attributed to Haijun Yang.

31 records · Page 2Linked to original sources

arXiv2024

Study of residual artificial neural network for particle identification in the CEPC high-granularity calorimeter prototype

Particle Identification (PID) plays a central role in associating the energy depositions in calorimeter cells with the type of primary particle in a particle flow oriented detector system. In this paper, we propose novel PID methods based on the Residual Network (ResNet) architecture which enable the training of very deep networks, bypass the need to reconstruct feature variables, and ensure the generalization ability among various geometries of detectors, to classify electromagnetic showers and hadronic showers. Using Geant4 simulation samples with energy ranging from 5 GeV to 120 GeV, the efficacy of Residual Connections is validated and the performance of our model is compared with Boosted Decision Trees (BDT) and other pioneering Artificial Neural Network (ANN) approaches. In shower classification, we observe an improvement in background rejection over a wide range of high signal efficiency ($> 95\%$). These findings highlight the prospects of ANN with Residual Blocks for imaging detectors in the PID task of particle physics experiments.

hep-ex↗

arXiv2024

Reconstructing Close Human Interactions from Multiple Views

This paper addresses the challenging task of reconstructing the poses of multiple individuals engaged in close interactions, captured by multiple calibrated cameras. The difficulty arises from the noisy or false 2D keypoint detections due to inter-person occlusion, the heavy ambiguity in associating keypoints to individuals due to the close interactions, and the scarcity of training data as collecting and annotating motion data in crowded scenes is resource-intensive. We introduce a novel system to address these challenges. Our system integrates a learning-based pose estimation component and its corresponding training and inference strategies. The pose estimation component takes multi-view 2D keypoint heatmaps as input and reconstructs the pose of each individual using a 3D conditional volumetric network. As the network doesn't need images as input, we can leverage known camera parameters from test scenes and a large quantity of existing motion capture data to synthesize massive training data that mimics the real data distribution in test scenes. Extensive experiments demonstrate that our approach significantly surpasses previous approaches in terms of pose accuracy and is generalizable across various camera setups and population sizes. The code is available on our project page: https://github.com/zju3dv/CloseMoCap.

cs.CV↗

arXiv2023

A Communication Theory Perspective on Prompting Engineering Methods for Large Language Models

The springing up of Large Language Models (LLMs) has shifted the community from single-task-orientated natural language processing (NLP) research to a holistic end-to-end multi-task learning paradigm. Along this line of research endeavors in the area, LLM-based prompting methods have attracted much attention, partially due to the technological advantages brought by prompt engineering (PE) as well as the underlying NLP principles disclosed by various prompting methods. Traditional supervised learning usually requires training a model based on labeled data and then making predictions. In contrast, PE methods directly use the powerful capabilities of existing LLMs (i.e., GPT-3 and GPT-4) via composing appropriate prompts, especially under few-shot or zero-shot scenarios. Facing the abundance of studies related to the prompting and the ever-evolving nature of this field, this article aims to (i) illustrate a novel perspective to review existing PE methods, within the well-established communication theory framework; (ii) facilitate a better/deeper understanding of developing trends of existing PE methods used in four typical tasks; (iii) shed light on promising research directions for future PE methods.

cs.CL↗

arXiv2022

Remarkably strong magnetic response in molecules with polar groups

For more than a century, electricity and magnetism have been believed to always exhibit inextricable link due to the symmetry in electromagnetism. At the interface, polar groups that have polar charges, are indispensable to be considered, which interact directly with other polar charges/external charges/external electric fields. However, there is no report on the corresponding magnetic properties on these polar groups. Clearly, such asymmetry, that is, only the interaction between the polar groups and charges, is out of bounds. Here we show that those molecules with considerable polar groups, such as cellulose acetate (CA) and other cellulose derivatives with different polar groups, can have strong magnetic response, indicating that they are strongly paramagnetic. Density functional theory (DFT) calculation shows that the polarity greatly reduces the excitation energy from the state without net spin (singlet) to the state with net spin (triplet), making the considerable existence of magnetic moments on the polar groups. We note that the hydrophobic groups in these molecules have no magnetic moments, however, they make the molecules aggregate to amply the magnetic effect of the magnetic moments in the polar groups, so that these magnetic moments can induce the strong paramagnetism. Our observations suggest a recovery of the symmetry with inextricable link between the electricity and magnetism at the interface. The findings leave many imaginations of the role of the magnetic interaction in biological systems as well as other magnetic applications considering that many of those polar materials are biological materials, pharmaceutical materials, chemical raw materials, and even an essential hormone in agricultural production.

cond-mat.soft↗

arXiv2021

Super strong paramagnetism induced by polar functional groups and water

We experimentally demonstrate that some commonly used materials such as cellulose acetate and chitin which are traditionally considered to be non-magnetic show super strong paramagnetism in aqueous solutions under ambient conditions when they are agglomerated by nanoparticles. Theoretical computations show that strongly polar functional groups can reduce the potential barrier for a singlet-triplet interconversion with the help of surrounding water, inducing the magnetic moments. These magnetic moments distributed on the surfaces of the nanoparticles, which make a large number of magnetic moments gather in a very small space, greatly enhance the alignment of the moments along and amplify the effect of the external magnetic field, resulting in the super strong paramagnetism. Our findings suggest that the polar functional group may always induce paramagnetism and the magnetic effect may be universal as the electric effects since the polarization is very common in materials.

cond-mat.soft↗

arXiv2020

Super strong paramagnetism of aromatic peptides adsorbed with monovalent cations

We experimentally demonstrated that the AYFFF self-assemblies adsorbed with various monovalent cations (Na+, K+, and Li+) show unexpectedly super strong paramagnetism. The key to the super strong paramagnetism lies in the hydrated cation-π interactions between the monovalent cations and the aromatic rings in the AYFFF assemblies, which endows the AYFFF-cations complex with magnetic moments.

physics.bio-ph↗

arXiv2020

Unexpectedly super strong paramagnetism of aromatic peptides due to cations of divalent metals

The magnetism of most biological systems has not been characterized, which directly impedes our understanding of many magnetic field-related phenomena, including magnetoreception and magnetic bio-effects. Here we measured the magnetic susceptibility of aromatic peptide AYFFF self-assemblies in the presence or absence of divalent metal cations in liquid phase at room temperature. Unexpectedly, the magnetic susceptibilities of AYFFF self-assemblies in the chloride solution of various divalent cations (Mg2+, Zn2+, and Cu2+) show super strong paramagnetism. We attribute the super strong paramagnetism to existence of the magnetic moments on the cations adsorbed on aromatic rings in the AYFFF assemblies through hydrated cation-π interactions, where the adsorbed cations display non-divalent behavior with unpaired electron spins. Our results indicate the super strong paramagnetism or potential ferromagnetism in the aromatic ring-enriched biomolecules when there are enough cations of divalent metals adsorbed. The findings not only provide fundamental information for understanding the magnetism of biological systems, provoke insights for investigating the origin of magnetoreception and bio-effects of magnetic fields, but also help developing future magnetic-control techniques on aromatic ring-enriched biomolecules and drugs in living organisms, as well as biomaterial fabrication and manipulation.

cond-mat.soft↗

arXiv2020

Unexpectedly super strong paramagnetism of aromatic peptides due to cations

We found that the AYFFF self-assemblies in the chloride solution of some divalent cations ($Zn^{2+}, Mg^{2+},$ and $Cu^{2+}$) display super strong paramagnetism, which may approach the mass susceptibility of ferromagnetism. We attribute the observed super strong paramagnetism to the existence of the aromatic rings, which interact with the cations through cation-π interaction.

physics.bio-ph↗

arXiv2020

Unexpectedly strong diamagnetism and superparamagnetism of aromatic peptides due to self-assembling and cations

There is a considerable amount of work that shows the biomagnetism of organic components without ferromagnetic components at the molecular level, but it is of great challenge to cover the giant gap of biomagnetism between their experimental and theoretical results. Here, we show that the diamagnetism of an aromatic peptide, the AYFFF, is greatly enhanced for about 11 times by self-assembling, reaching two orders of magnitude higher than the mass susceptibility of pure water. Moreover, the AYFFF self-assemblies further mixed with ZnCl2 solution of sufficiently high concentrations display superparamagnetism, with the mass susceptibility reaching more than two orders of magnitude higher than the absolute value of pure water, which may approach the mass susceptibility of ferromagnetism. The aromatic rings in the peptide molecules and the cations are the keys to such a strong diamagnetism and superparamagnetism of aromatic peptides.

physics.bio-ph↗

arXiv2020

Enhanced contact angle hysteresis of salt aqueous solution on graphite surface by a tiny amount of cation

We experimentally observed the enhanced contact angle hysteresis (CAH) of dilute aqueous salt solution on graphite surface, i.e., 40.6$^\circ$, 34.6$^\circ$, and 27.8$^\circ$, for LiCl, NaCl, and KCl, indicating the effective tuning of the CAHs by cations. Molecular dynamics simulations reveal that the preferential adsorption of cations on the HOPG surface due to the cation-π interaction pins the water at the backward liquid-gas-solid interfaces, reducing the receding contact angle and hence enhancing the CAH. This finding provides a simple method to control the contact angle and the CAH of aqueous drops on graphitic surfaces such as graphene, carbon nanotube, biomolecules, and airborne pollutants.

physics.app-ph↗

arXiv2019

Precision Higgs Physics at CEPC

The discovery of the Higgs boson with its mass around 125 GeV by the ATLAS and CMS Collaborations marked the beginning of a new era in high energy physics. The Higgs boson will be the subject of extensive studies of the ongoing LHC program. At the same time, lepton collider based Higgs factories have been proposed as a possible next step beyond the LHC, with its main goal to precisely measure the properties of the Higgs boson and probe potential new physics associated with the Higgs boson. The Circular Electron Positron Collider~(CEPC) is one of such proposed Higgs factories. The CEPC is an $e^+e^-$ circular collider proposed by and to be hosted in China. Located in a tunnel of approximately 100~km in circumference, it will operate at a center-of-mass energy of 240~GeV as the Higgs factory. In this paper, we present the first estimates on the precision of the Higgs boson property measurements achievable at the CEPC and discuss implications of these measurements.

hep-ex↗

arXiv2013

High-precision Absolute Coordinate Measurement using Frequency Scanned Interferometry

In this paper, we report high-precision absolute position measurement performed with frequency scanned interferometry (FSI). We reported previously on measurement of absolute distance with FSI [1]. Absolute position is determined by several related absolute distances measured simultaneously. The achieved precision of 2-dimensional measurements is better than 1 micron, and in 3-dimensional measurements, the precision on X and Y is confirmed to be below 1 micron, while the confirmed precision on Z is about 2 microns, where the confirmation is limited by the lower precision of the moving stage in Z direction.

physics.ins-det↗

arXiv2011

Measurement of the WW Cross Section in 7 TeV pp Collisions with the ATLAS Detector

We report a measurement of the WW production cross section in pp collisions at 7 TeV. The WW leptonic decay channels are analyzed using data corresponding to 1.02 /fb of integrated luminosity collected by the ATLAS detector during 2011 at the CERN Large Hadron Collider. With 414 observed WW candidate events and an estimated background of 170$\pm$28 events, the measured WW production cross section is $48.2 \pm 4.0 {\rm(stat)} \pm 6.4 {\rm(syst)} \pm 1.8 {\rm(lumi)}$ pb, in agreement with the Standard Model NLO prediction of 46$\pm$3 pb.

hep-ex↗