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Strong shock propagation for the finite-source circular blast in a confined domain

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Applied mathematics and Mechanics(English Edition) 2024年第6期45卷 1071-1084页

作者： Qihang ma Kaileong CHONG Bofu WANG Quan ZHOU Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China Shanghai Institute of Aircraft Mechanics and Control Shanghai 200092China

The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible *** reflection of the primary shock and its propagation within a confined domain are studied both theoretically and numerically in this *** the assumption of strong shock,the scaling law governing propagation of the main shock is *** dimensionless frequency of reflected shock propagation is associated with the confined *** numerical simulation for the circular explosion problem in a confined domain is performed for *** the influence of confinement,the principal shock wave systematically undergoes reflection within the domain until it weakens,leading to the non-monotonic attenuation of kinetic energy in the explosion fireball and periodic oscillations of the fireball volume with a certain *** simulation results indicate that the frequency of kinetic energy attenuation and the volume oscillation of the explosive fireball align consistently with the scaling law.

关键词： explosion confinement main shock frequency

Investigation on the Velocity-Dependent Adhesion Hysteresis via Molecular Dynamics Simulation

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Acta Mechanica Solida Sinica 2024年第3期37卷 423-429页

作者： Jinshan He Yiran Li Zhaoyang ma Ganyun Huang Department of Mechanics School of Mechanical EngineeringTianjin UniversityTianjin300350China

Adhesion plays an important role in miniaturized devices and technologies,which depends not only on indentation depth but also on the history of contact making and breaking,giving rise to adhesion *** the present work,adhesion hysteresis has been investigated via molecular dynamics simulations on approaching and retracting a rigid tip to and from a *** results show that hysteresis in the force-displacement curve that depends on approaching and retraction velocities arises under both elastic and plastic *** underlying mechanisms have been *** implications of the results in friction have been discussed briefly.

关键词： Adhesion hysteresis Molecular dynamics simulation Contact instability Plastic deformation

Diagnostic performance of dynamic contrast-enhanced magnetic resonance imaging parameters and serum tumor markers in rectal carcinoma prognosis

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World Journal of Gastrointestinal Oncology 2024年第5期16卷 1796-1807页

作者： Ren-Qi Mu Jun-Wei Lv Cai-Yun ma Xiao-Hui ma Dong Xing Hou-Sheng ma Department of Radiology Yantai Mountain HospitalYantai 264001Shandong ProvinceChina Department of Radiology Yantai Yuhuangding HospitalYantai 264000Shandong ProvinceChina Department of Gynaecology Yantai Yuhuangding HospitalYantai 264000Shandong ProvinceChina The First Clinical Medical College Xinjiang Medical UniversityUrumqi 830011Xinjiang Uygur Autonomous RegionChina

BACKGROUND Rectal carcinoma(RC),one of the most common malignancies globally,presents an increasing incidence and mortality year by year,especially among young people,which seriously affects the prognosis and quality of life of *** present,dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)parameters and serum carbohydrate antigen 19-9(CA19-9)and CA125 Levels have been used in clinical practice to evaluate the T stage and differentiation of ***,the accuracy of these evaluation modalities still needs further *** study explores the application and value of these methods in evaluating the T stage and differentiation degree of *** To analyze the diagnostic performance of DCE-MRI parameters combined with serum tumor markers(TMs)in assessing pathological processes and prognosis of RC *** A retrospective analysis was performed on 104 RC patients treated at Yantai Yuhuangding Hospital from may 2018 to January *** were categorized into stages T1,T2,T3,and T4,depending on their T stage and differentiation *** addition,they were assigned to low(L group)and moderate-high differentiation(M+H group)groups based on their differentiation *** levels of DCE-MRI parameters and serum CA19-9 and CA125 in different groups of patients were *** addition,the value of DCE-MRI parameters[volume transfer constant(Ktrans),rate constant(Kep),and extravascular extracellular volume fraction(Ve)in assessing the differentiation and T staging of RC patients was ***,the usefulness of DCE-MRI parameters combined with serum CA19-9 and CA125 Levels in the evaluation of RC differentiation and T staging was *** Ktrans,Ve,CA19-9 and CA125 were higher in the high-stage group and L group than in the low-stage group and M+H Group,respectively(P<0.05).The areas under the curve(AUCs)of the Ktran and Ve parameters were 0.638 and 0.694 in the diagnosis of high and low stages,respectively,and 0.672 and 0

关键词： Rectal carcinoma Volume transfer constant Rate constant Extravascular extracellular volume fraction Serum carbohydrate antigen 19-9 Serum carbohydrate antigen 125

Guaranteed Cost Attitude Tracking Control for Uncertain Quadrotor Unmanned Aerial Vehicle Under Safety Constraints

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1447-1457页

作者： Qian ma Peng Jin Frank L.Lewis School of Automation Nanjing University of Science and TechnologyNanjing 210094China UTA Research Institute University of Texas at ArlingtonFort WorthTexas 76118 USA IEEE

In this paper,guaranteed cost attitude tracking con-trol for uncertain quadrotor unmanned aerial vehicle(QUAV)under safety constraints is ***,an augmented system is constructed by the tracking error system and reference *** transformation aims to convert the tracking control prob-lem into a stabilization control ***,control barrier function and disturbance attenuation function are designed to characterize the violations of safety constraints and tolerance of uncertain disturbances,and they are incorporated into the reward function as penalty *** on the modified reward function,the problem is simplified as the optimal regulation problem of the nominal augmented system,and a new Hamilton-Jacobi-Bellman equation is ***,critic-only rein-forcement learning algorithm with a concurrent learning tech-nique is employed to solve the Hamilton-Jacobi-Bellman equa-tion and obtain the optimal *** proposed algorithm can not only ensure the reward function within an upper bound in the presence of uncertain disturbances,but also enforce safety *** performance of the algorithm is evaluated by the numerical simulation.

关键词： Attitude tracking control quadrotor unmanned aerial vehicle(QUAV) reinforcement learning safety constraints uncertain disturbances.

Interfacial tribochemical kinetics: A new perspective on superlubricity of diamond-like carbon films

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Science China(Technological Sciences) 2024年第7期67卷 2050-2052页

作者： CHEN WeiQi ma Tian-Bao State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

Friction is considered one of the primary challenges affecting the performance of machine operations and is a significant source of energy loss in industrial applications. About 30%of disposable energy is consumed by ... 详细信息

关键词： kinetics friction operations

Growth,optical dispersion and magnetic behavior of Dy^(3+) doped yttrium iron garnet crystals

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Journal of Rare Earths 2024年第6期42卷 1110-1117,I0004页

作者： Yating Fang Hui Shen Yudie ma Shijie Liao Shuang Xia Tian Tian Ding Zhou Yunfeng ma Jiayue Xu Institute of Crystal Growth School of Materials Science and EngineeringShanghai Institute of Technology National Engineering Center of Electromagnetic Radiation Control materials School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of China

Y_(3)Fe_(5)O_(12)(YIG)crystals are highly desirable for the fabrication of mid-infrared isolators with the rapid growth of optical communications,although it is rather challenging to grow large size and high-quality single ***^(3+)doping is expected to improve the optical and magneto-optical prope ***,high quality Dy:YIG crystals and the adjustment of Dy^(3+)on the structure and optical behavior of YIG crystal remain unclear,impeding its practical ***,a series of Y_(3-x)Dy_(x)Fe_(5)O_(12)(x=0,0.5,1.0,1.5,3)solid solution crystals was grown by the flux-Bridgman method and single crystals up to 25 mm were *** the introduction of Dy^(3+),lattice parameters are gradually enlarged from 1.2379 nm(YIG)to 1.2420 nm(DyIG).Typical Dy^(3+)absorption peaks are observed around 1070,1265 and 1670 *** refractive index decreases from 2.37(500 nm)to 2.10(2500 nm)for YIG crystal,and it reduces from 2.47(500 nm)to 2.16(2500 nm)for DyIG *** optical bandgaps remain almost unchanged for Dy:YIG *** optical dispersion of the refractive indices was finely fitted by the Wemple and DiDomenico(WDD)and the Sellmeier models,*** the increase of Dy^(3+)content,the saturation magnetization(Ms)decreases significantly from 23.62 emu/g(YIG)to 5.33 emu/g(DyIG).Small coercive field is persisted for this system,endowing small external magnetic *** results provide valuable references for the manipulation of rare earths on the properties of magnetooptical crystals,which is beneficial to the design of high-performance garnet crystals for the application of optical switching and non-reciprocal related devices.

关键词： magneto-optical crystal Yttrium iron garnet Dy^(3+)doping Crystal growth Optical dispersion Rare earths

Simulation of nuclear isomer production in laser-induced plasma

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matter and Radiation at Extremes 2024年第5期9卷 1-9页

作者： Zhiguo ma Yumiao Wang Yi Yang Youjing Wang Kai Zhao Yixin Li Changbo Fu Wanbing He Yugang ma Key Laboratory of Nuclear Physics and Ion-Beam Application(MoE) Institute of Modern PhysicsFudan UniversityShanghai 200433China

Nuclear isomers play essential roles in various fields,including stellar nucleosynthesis,nuclear clocks,nuclear batteries,clean nuclear energy,and-ray *** technological advances in high-intensity lasers have made it possible to excite or de-excite nuclear isomers using table-top laser *** a particle-in-cell code,we investigate the interaction of a laser with a nanowire array and calculate the production rates of the^(73m)Ge(E_(1)=13.3 keV)and^(107m)Ag(E_(1)=93.1 keV)***^(73m1)Ge,production by Coulomb excitation is found to contribute a peak efficiency of 1.0×10^(19) particles s^(−1)J^(−1),while nuclear excitation by electron capture(NEEC)contributes a peak of 1.65×10^(11)particles s^(−1)J^(−1).These results indicate a high isomeric production ratio,as well as demonstrating the potential for confirming the existence of NEEC,a long-expected but so far experimentally unobserved fundamental process.

关键词： process. isomers excitation

Unravelling the nature of the active species as well as the Mn doping effect over gamma-Al_(2)O_(3) catalyst for eliminating AsH_(3) and PH_(3)

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Journal of Environmental Sciences 2024年第2期136卷 213-225页

作者： Bowen Xu Jiaxin Qu Xueqian Wang Langlang Wang Yu Pu Ping Ning Yibing Xie Yixing ma Qiang ma Faculty of Environmental Science and Engineering Kunming University of Science and TechnologyKunming 650500China School of Architecture and Civil Engineering Chengdu UniversityChengdu 610106China

To investigate the enhancing effect of Mn on the performance of simultaneous catalytic oxidation of AsH_(3)and PH_(3)by CuO-Al_(2)O_(3)in a reducing atmosphere under micro-oxygen conditions,Cu-Mn modifiedγ-Al_(2)O_(3)catalysts were *** characteristics of the catalysts showed that Mn reduced the crystallinity of the active CuO component,increased the number of oxygen vacancies and acidic sites on the catalyst surface,enhanced the mobility of surface oxygen,and the interaction between copper and manganese promoted the redox cycling ability of the catalysts and improved their oxidation performance,which increased the conversion frequency(TOF)by 2.54×10^(-2)to 3.07×10^(-2)sec^(-1).On the other hand,the introduction of Mn reduced the production of phosphate and As_(2)O_(3)on the catalyst surface by30.96%and 44.9%,which reduced the coverage and inerting of the active sites by phosphate and As_(2)O_(3),resulting in an 8 hr(6 hr)improvement in the stability of PH_(3)(AsH_(3))removal.

关键词： AsH_(3)-PH_(3)removal Oxygen activation Mn doping Stability enhancement

An improved pulse coupled neural networks model for semantic IoT

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Digital Communications and Networks 2024年第3期10卷 557-567页

作者： Rong ma Zhen Zhang Yide ma Xiping Hu Edith C.H.Ngai Victor C.M.Leung School of Information Science and Engineering Lanzhou UniversityLanzhou 730000China School of Medical Technology Beijing Institute of TechnologyBeijing100081China Department of Electrical and Electronic Engineer The University of Hong KongHong Kong 999077China College of Computer Science and Software Engineering Shenzhen UniversityShenzhen 518060China Department of Electrical and Computer Engineering the University of British ColumbiaVancouverBC V6T 1Z4Canada

In recent years,the Internet of Things(IoT)has gradually developed applications such as collecting sensory data and building intelligent services,which has led to an explosion in mobile data ***,with the rapid development of artificial intelligence,semantic communication has attracted great attention as a new communication ***,for IoT devices,however,processing image information efficiently in real time is an essential task for the rapid transmission of semantic *** the increase of model parameters in deep learning methods,the model inference time in sensor devices continues to *** contrast,the Pulse Coupled Neural Network(PCNN)has fewer parameters,making it more suitable for processing real-time scene tasks such as image segmentation,which lays the foundation for real-time,effective,and accurate image ***,the parameters of PCNN are determined by trial and error,which limits its *** overcome this limitation,an Improved Pulse Coupled Neural Networks(IPCNN)model is proposed in this *** IPCNN constructs the connection between the static properties of the input image and the dynamic properties of the neurons,and all its parameters are set adaptively,which avoids the inconvenience of manual setting in traditional methods and improves the adaptability of parameters to different types of *** segmentation results demonstrate the validity and efficiency of the proposed self-adaptive parameter setting method of IPCNN on the gray images and natural images from the matlab and Berkeley Segmentation *** IPCNN method achieves a better segmentation result without training,providing a new solution for the real-time transmission of image semantic information.

关键词： Internet of things(IoT) Semantic information Real-time application Improved pulse coupled neural network Image segmentation