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Number of Solitons Emerged in the Initial Profile of Shallow Water Using Convolutional Neural Networks

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Journal of Systems Science & Complexity 2024年第2期37卷 463-479页

作者： WANG zhen CUI Shikun School of Mathematical Sciences Dalian University of TechnologyDalian 116024China School of Mathematical Sciences Beihang UniversityBeijing 100191China

The soliton resolution conjecture proposes that the initial value problem can evolve into a dispersion part and a soliton part.However,the problem of determining the number of solitons that form in a given initial profile remains unsolved,except for a few specific cases.In this paper,the authors use the deep learning method to predict the number of solitons in a given initial value of the Korteweg-de Vries(KdV)equation.By leveraging the analytical relationship between Asech^(2)(x)initial values and the number of solitons,the authors train a Convolutional Neural Network(CNN)that can accurately identify the soliton count from spatio-temporal data.The trained neural network is capable of predicting the number of solitons with other given initial values without any additional assistance.Through extensive calculations,the authors demonstrate the effectiveness and high performance of the proposed method.

关键词： Convolutional neural network deep learning method KdV equation soliton

Nuclear charge radius predictions by kernel ridge regression with odd-even effects

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Nuclear Science and Techniques 2024年第2期35卷 94-102页

作者： Lu Tang zhen-Hua Zhang Mathematics and Physics Department North China Electric Power UniversityBeijing 102206China Hebei Key Laboratory of Physics and Energy Technology North China Electric Power UniversityBaoding 071000China

The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models.These are:(i)the isospin-dependent A^(1∕3) formula,(ii)relativistic continuum Hartree-Bogoliubov(RCHB)theory,(iii)Hartree-Fock-Bogoliubov(HFB)model HFB25,(iv)the Weizsacker-Skyrme(WS)model WS*,and(v)HFB25*model.In the last two models,the charge radii were calculated using a five-parameter formula with the nuclear shell corrections and deformations obtained from the WS and HFB25 models,respectively.For each model,the resultant root-mean-square deviation for the 1014 nuclei with proton number Z≥8 can be significantly reduced to 0.009-0.013 fm after considering the modification with the EKRR method.The best among them was the RCHB model,with a root-mean-square deviation of 0.0092 fm.The extrapolation abilities of the KRR and EKRR methods for the neutron-rich region were examined,and it was found that after considering the odd-even effects,the extrapolation power was improved compared with that of the original KRR method.The strong odd-even staggering of nuclear charge radii of Ca and Cu isotopes and the abrupt kinks across the neutron N=126 and 82 shell closures were also calculated and could be reproduced quite well by calculations using the EKRR method.

关键词： Nuclear charge radius Machine learning Kernel ridge regression method

Design Research of a Novel Aftercool-Humidifier Concept for Humid Air Turbine Cycle

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Journal of Thermal Science 2024年第3期33卷 951-969页

作者： ZHANG Junzheng XU zhen School of Energy and Power Engineering Shandong UniversityJi’nan250061China Shandong Engineering Laboratory for High-efficiency Energy Conservation and Energy Storage Technology&Equipment Shandong UniversityJi’nan250061China

Humid air turbine cycle(HAT)has potential of electrical efficiencies comparable to combined cycle,with lower investment cost and NO_(x) emission.The typical heat exchanger network of HAT consists of intercooler(if there is),aftercooler,recuperator,economizer and humidifier,which brings higher efficiency but makes the system more complex.To simplify HAT layout,a novel humidifier concept is proposed by integrating the aftercooler into traditional counter-current humidifier.Based on this concept,a one-dimensional model including pressure drop and exergy calculation is established to distinguish the thermodynamic and hydrodynamic characteristics,and then the structural parameters,such as the number of rows and columns,tube diameter,pitch and type for a micro HAT are identified.The results show that the aftercool-humidifier plays the same role as original aftercooler and humidifier,and can match the in-tube air,out-tube air and water stream well with lower volume.In the case of micro HAT cycle,the volume of heat and mass transfer area can be reduced by 47%compared with traditional design.The major thermal resistance occurred in the convection heat transfer process inside the tube;however,using enhanced tube cannot effectively improve the compactness of device.

关键词： humid air turbine cycle humidifier thermodynamic analysis one-dimensional model

Design Optimization and Operating Performance of S-CO_(2) Brayton Cycle under Fluctuating Ambient Temperature and Diverse Power Demand Scenarios

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Journal of Thermal Science 2024年第1期33卷 190-206页

作者： YANG Jingze YANG zhen DUAN Yuanyuan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce costs.Since the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand scenarios.In addition,the cycle design condition will directly affect the off-design performance.In this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced innovatively.Results show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient temperatures.The average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient temperature.With multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature period.If the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.

关键词： supercritical CO_(2)Brayton cycle ambient temperature fluctuating power demand scenarios design optimization off-design performance

Recent progress in self-propelled particles

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Journal of Hydrodynamics 2024年第1期36卷 61-77页

作者： zhen-yu Ouyang Jian-zhong Lin Laboratory of Impact and Safety Engineering Ministry of EducationNingbo UniversityNingbo315201China Department of Mechanics State Key Laboratory of Fluid Power and Mechatronic SystemsZhejiang UniversityHangzhou310027China

Self-propelled particles are commonly found in a large number of planktonic organisms such as bacteria,fungi,and algae in nature,and researchers have taken a long interest in exploring their swimming mechanisms for more than a century.Especially in the past 20 years,with the development of computational fluid dynamics and flow display technology,as well as the need for the design of synthetic self-propelled particles and micro-swimming devices,self-propelled particles have become the forefront and hotspot of current research in the field of fluid mechanics.This paper first introduces the swimming characteristics of common self-propelled particles,leading to a classic“squirmer”type self-propelled particle model.On this basis,a systematic introduction and summary of the theoretical and numerical simulation research of“squirmer”will be conducted.Finally,the main challenges and opportunities faced by the current research will be summarized.

关键词： Self-propelled particles multiphase flow hydrodynamic interaction

Polynomial-Time Key-Recovery Attacks Against NTRURe Encrypt from ASIACCS'15

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Journal of Systems Science & Complexity 2024年第3期37卷 1308-1325页

作者： LIU zhen PAN Yanbin zhenG Jinwei School of Cyber Science and Technology Hubei Key Laboratory of Applied MathematicsHubei UniversityWuhan 430062China Key Laboratory of Mathematics Mechanization Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100190China

In ASIACCS 2015, Nu nez, et al. proposed a proxy re-encryption scheme, named NTRURe Encrypt, based on NTRU, which allows a proxy to translate ciphertext under the delegator’s public key into a re-encrypted ciphertext that can be decrypted correctly by delegatee’s private key. Because of the potential resistance to quantum algorithm, high efficiency and various applications in real life,NTRURe Encrypt has drawn lots of attention and its security has been widely discussed and analyzed.In PQCrypto2019, Liu, et al. proposed two key recovery attacks against it. However, their first attack heavily relies on a weaken decryption oracle, and the second attack needs to collect about 260ciphertexts from the same message by theoretical analysis, which makes both of the attacks unrealistic. In this paper, inspired by the broadcast attack against NTRU, the authors find out that for NTRURe Encrypt the delegator and the delegatee can efficiently recover each other’s private key in polynomial time without any unrealistic assumptions. In addition, the authors also show how to fix NTRURe Encrypt to resist the proposed attacks. As a by-product, the authors also show how to commit broadcast attacks against NTRU 2001 with even dg, which was thought infeasible before.

关键词： Broadcast attack key recovery NTRU NTRUReEncrypt

Fusion of Spiral Convolution-LSTM for Intrusion Detection Modeling

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Computers, Materials & Continua 2024年第5期79卷 2315-2329页

作者： Fei Wang zhen Dong School of Cyberspace Security Gansu University of Political Science and LawLanzhou73000China

Aiming at the problems of low accuracy and slow convergence speed of current intrusion detection models,SpiralConvolution is combined with Long Short-Term Memory Network to construct a new intrusion detection model.The dataset is first preprocessed using solo thermal encoding and normalization functions.Then the spiral convolution-Long Short-Term Memory Network model is constructed,which consists of spiral convolution,a two-layer long short-term memory network,and a classifier.It is shown through experiments that the model is characterized by high accuracy,small model computation,and fast convergence speed relative to previous deep learning models.The model uses a new neural network to achieve fast and accurate network traffic intrusion detection.The model in this paper achieves 0.9706 and 0.8432 accuracy rates on the NSL-KDD dataset and the UNSWNB-15 dataset under five classifications and ten classes,respectively.

关键词： Intrusion detection deep learning spiral convolution long and short term memory networks 1D-spiral convolution

Epileptic brain network mechanisms and neuroimaging techniques for the brain network

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Neural Regeneration Research 2024年第12期19卷 2637-2648页

作者： Yi Guo Zhonghua Lin zhen Fan Xin Tian Department of Neurology Sichuan Provincial People’s HospitalUniversity of Electronic Science and Technology of ChinaChengduSichuan ProvinceChina Sichuan Provincial Center for Mental Health Sichuan Provincial People’s HospitalUniversity of Electronic Science and Technology of ChinaChengduSichuan ProvinceChina Department of Geriatrics Sichuan Provincial People’s HospitalUniversity of Electronic Science and Technology of ChinaChengduSichuan ProvinceChina Department of Neurology Chongqing Key Laboratory of NeurologyThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina

Epilepsy can be defined as a dysfunction of the brain network,and each type of epilepsy involves different brain-network changes that are implicated diffe rently in the control and propagation of interictal or ictal discharges.Gaining more detailed information on brain network alterations can help us to further understand the mechanisms of epilepsy and pave the way for brain network-based precise therapeutic approaches in clinical practice.An increasing number of advanced neuroimaging techniques and electrophysiological techniques such as diffusion tensor imaging-based fiber tra ctography,diffusion kurtosis imaging-based fiber tractography,fiber ball imagingbased tra ctography,electroencephalography,functional magnetic resonance imaging,magnetoencephalography,positron emission tomography,molecular imaging,and functional ultrasound imaging have been extensively used to delineate epileptic networks.In this review,we summarize the relevant neuroimaging and neuroelectrophysiological techniques for assessing structural and functional brain networks in patients with epilepsy,and extensively analyze the imaging mechanisms,advantages,limitations,and clinical application ranges of each technique.A greater focus on emerging advanced technologies,new data analysis software,a combination of multiple techniques,and the construction of personalized virtual epilepsy models can provide a theoretical basis to better understand the brain network mechanisms of epilepsy and make surgical decisions.

关键词： electrophysiological techniques epilepsy functional brain network functional magnetic resonance imaging functional near-infrared spectroscopy machine leaning molecular imaging neuroimaging techniques structural brain network virtual epileptic models

First Passage Density of Brownian Motion with Two-sided Piecewise Linear Boundaries

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1505-1520页

作者： zhen YU Mao Zai TIAN Center for Applied Statistics School of StatisticsRenmin University of ChinaBeijing 100872P.R.China School of Mathematics and Data Science Changji UniversityChangji 831100P.R.China

The first passage time has many applications in fields like finance,econometrics,statistics,and biology.However,explicit formulas for the first passage density have only been obtained for a few cases.This paper derives an explicit formula for the first passage density of Brownian motion with twosided piecewise continuous boundaries which may have some points of discontinuity.Approximations are used to obtain a simplified formula for estimating the first passage density.Moreover,the results are also generalized to the case of two-sided general nonlinear boundaries.Simulations can be easily carried out with Monte Carlo method and it is demonstrated for several typical two-sided boundaries that the proposed approximation method offers a highly accurate approximation of first passage density.

关键词： Boundary non-crossing probability first density passage density two-sided piecewise continuous boundaries Brownian motion