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Characteristics of Emission Non-nulling Pulsars Through Simulation

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Research in Astronomy and Astrophysics 2024年第4期24卷 91-102页

作者： Rai yuen Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Xinjiang Key Laboratory of Radio Astrophysics Chinese Academy of SciencesUrumqi 830011China Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210008China SIfA School of PhysicsUniversity of SydneySydneyNSW2006Australia

We investigate the population and several properties of radio pulsars whose emission does not null(non-nulling)through simulation of a large pulsar *** from a pulsar is identified as non-nulling if(i)the emission does not cease across the whole pulse profile,and(ii)the emission is ***(i),we adopt a model for switching in the plasma charge density,and emission persists if the charge density is ***(ii),we assume that detectable emission originates from source points where it is emitted tangentially to the magnetic field-line and parallel to the *** find that pulsars exhibiting non-nulling emission possess obliquity angles with an average of 42°.5,and almost half the samples maintain a duty cycle between 0.05 and ***,the pulsar population is not fixed but dependent on the obliquity angle,with the population peaking at 20°.In addition,three evolutionary phases are identified in the pulsar population as the obliquity angle evolves,with the majority of samples having an obliquity angle between 20°and 65°.Our results also suggest that emission from a pulsar may evolve between nulling and non-nulling during its lifetime.

关键词： radiation mechanisms:non thermal stars:neutron (stars:)pulsars:general

Collaborative Distributed AC Optimal Power Flow: A Dual Decomposition Based Algorithm

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Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1414-1423页

作者： Zheyuan Cheng Mo-yuen Chow IEEE Department of Electrical and Computer Engineering North Carolina State University

We propose a dual decomposition based algorithm that solves the AC optimal power flow(ACOPF) problem in the radial distribution systems and microgrids in a collaborative and distributed manner. The proposed algorithm adopts the second-order cone program(SOCP) relaxed branch flow ACOPF model. In the proposed algorithm, bus-level agents collaboratively solve the global ACOPF problem by iteratively sharing partial variables with its 1-hop neighbors as well as carrying out local scalar computations that are derived using augmented Lagrangian and primal-dual subgradient methods. We also propose two distributed computing platforms, i. e., high-performance computing(HPC) based platform and hardware-in-theloop(HIL) testbed, to validate and evaluate the proposed algorithm. The computation and communication performances of the proposed algorithm are quantified and analyzed on typical IEEE test systems. Experimental results indicate that the proposed algorithm can be executed on a fully distributed computing structure and yields accurate ACOPF solution. Besides, the proposed algorithm has a low communication overhead.

关键词： Distributed convex optimization distributed en-ergy management system optimal power flow primal-dual de-composition

OPTIMAL PROPORTIONAL REINSURANCE UNDER DEPENDENT RISKS

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Journal of Systems Science & Complexity 2012年第6期25卷 1171-1184页

作者： Fengqing HU Kam C yuen Department of Mathematics and Center for Financial Engineering Soochow University Department of Statistics and Actuarial Science University of Hong KongHong KongChina

This paper considers a correlated risk model with thinning-dependence structure. The au- thors investigate the optimal proportional reinsurance that maximizes the adjustment coefficient and the optimal proportional reinsurance under mean variance principle for the proposed model. The au- thors derive the optimal solutions and the numerical illustrations to show the impact of the dependence among the classes of business on the optimal reinsurance arrangements.

关键词： Adjustment coefficient mean-variance principle optimal proportional reinsurance thinning-dependence structure.

All-parameters Rayleigh wave inversion

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Earthquake Engineering and Engineering Vibration 2021年第2期20卷 517-534页

作者： Xiao-Hui Yang Ka-Veng yuen State Key Laboratory of Internet of Things for Smart City and Department of Civil and Environmental Engineering University of MacaoMacao 999078China

Since S-wave velocity of the subsurface is an important parameter in near surface applications,many studies have been conducted for its *** the various methods that use surface waves or body waves,Rayleigh wave inversion is the most *** practice,the densities and P-wave velocities of different layers are usually assumed to be known to avoid ill-posed problems,as they have less influence on the dispersion ***,improper assignment of these two groups of parameters leads to inaccurate estimation of the S-wave velocity *** order to address this problem,the all-parameters Rayleigh wave inversion strategy is proposed in which the S-wave velocities,layer thicknesses,densities and P-wave velocities of different layers are included as the unknown parameters for ***,the transitional Markov Chain Monte Carlo(TMCMC)algorithm is applied for the implementation of all-parameters Rayleigh wave *** simulated example and two real-test applications are demonstrated to verify the capability of the proposed method in the estimation of the S-wave velocity profile,the densities and the P-wave ***,it is verified that the proposed method achieved more accurate S-wave velocity profile estimation than the traditional approach.

关键词： all-parameters Rayleigh wave inversion Bayesian S-wave velocity profile TMCMC algorithm uncertainty quantification

Total colorectal and terminal ileal duplication presenting as intussusception and intestinal obstruction

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World Journal of Gastroenterology 2012年第43期18卷 6338-6340页

作者： yuen Chi Ho Department of Radiology Queen Mary HospitaHong Kong China

Colonic intussusception and gastrointestinal duplication are diseases that arise in young children. The clinical presentation of adult cases of intussusception and enteric duplication is non-specific and thus poses a diagnostic challenge. A computed tomography (CT) scan is recommended in adult cases as the most sensitive diagnostic tool and the pathognomonic finding of outer intussuscepiens and central intussusceptum is diagnostic. A septum of a duplicated colon in a non-intussuscepted segment has been rarely reported in the literature. With advancements in radiological imaging technology and the increased availability of CT scanners, the capacity for a correct pre-operative diagnosis has been significantly enhanced. Our current case report illustrates the importance of considering an uncommon etiology for enteric intussusception and duplication as a differential diagnosis of acute abdomen in an adult patient. Our analyses of this patient also highlight the successful use of CT scanning to make this diagnosis.

关键词： Ileal duplication Colonic duplication Intussusception Intestinal obstruction

Another avian influenza A subtype jumping into human:this time is H7N4

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Science Bulletin 2018年第16期63卷 1025-1026页

作者： Kwok-Yung yuen State Key Laboratory of Emerging Infectious Diseases Li Ka Shing Faculty of Medicine University of Hong Kong

Avian influenza viruses have been first known to jump the interspecies barrier and cause human infections since 1959[1].However,avian influenza was not considered a serious threat to public health until 1997,when the influenza A(H5N1)virus caused an outbreak in Hong Kong with 18 cases including six deaths[2].The A(H5N1)epidemic has never stopped despite poultry immu-

关键词：流行性感冒病毒种鸟子类型公共健康家禽免疫盒子流行病死亡

Bayesian Rayleigh wave inversion with an unknown number of layers

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Earthquake Engineering and Engineering Vibration 2020年第4期19卷 875-886页

作者： Ka-Veng yuen Xiao-Hui Yang State Key Laboratory of Internet of Things for Smart City and Department of Civil and Environmental Engineering University of Macao999078MacaoChina

Surface wave methods have received much attention due to their efficient, flexible and convenient characteristics. However, there are still critical issues regarding a key step in surface wave inversion. In most existing methods, the number of layers is assumed to be known prior to the process of inversion. However, improper assignment of this parameter leads to erroneous inversion results. A Bayesian nonparametric method for Rayleigh wave inversion is proposed herein to address this problem. In this method, each model class represents a particular number of layers with unknown S-wave velocity and thickness of each layer. As a result, determination of the number of layers is equivalent to selection of the most applicable model class. Regarding each model class, the optimization search of S-wave velocity and thickness of each layer is implemented by using a genetic algorithm. Then, each model class is assessed in view of its efficiency under the Bayesian framework and the most efficient class is selected. Simulated and actual examples verify that the proposed Bayesian nonparametric approach is reliable and efficient for Rayleigh wave inversion, especially for its capability to determine the number of layers.

关键词： Bayesian model class selection generalized r/t coefficients algorithm genetic algorithm inversion of Rayleigh wave number of layers

Formic acid oxidation by iridium single-atom catalysts on nitrogendoped carbon

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Science China Chemistry 2020年第9期63卷 1171-1172页

作者： Huang Zhou yuen Wu Hefei National Laboratory for Physical Sciences at the Microscale Collaborative Innovation Center of Chemistry for Energy Materials(iChEM)School of Chemistry and Materials Scienceand National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230026China

The challenge of the depletion of traditional fossil fuels forces researchers to develop sustainable and highly effective energy storage and conversion *** formic acid fuel cells(DFAFCs)exhibit great potential applications in small,lightweight and long-lasting portable power sources,due to the inherent advantages of formic acid,e.g.,safer and easier to store and handle than hydrogen,faster electro-oxidation kinetics than ethanol and lower fuel crossover through the Nafion membrane than methanol[1].

关键词： kinetics methanol faster

Melt Evolution above a Spontaneously Retreating Subducting Slab in a Three-Dimensional Model

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Journal of Earth Science 2011年第2期22卷 137-142页

作者： Taras Gerya David A yuen Department of Earth Sciences Swiss Federal Institute of Technology(ETH Zurich)CH-8092 ZurichSwitzerland Adjunct Professor of Geology Department Moscow State University Department of Geology and Geophysics and Minnesota Supercomputing Institute University of MinnesotaMinneapolisMN 55415USA

Dehydration of the subducting slab favors the melting of the surrounding mantle. Water content and melt evolution atop a spontaneously retreating subducting slab are reported in a three- dimensional （3-D） model. We find that fluids, including water and melts in the rocks, vary substantially along the trench, which cannot be found in two-dimensional （2-D） models. Their maxima along the subducting slab are mainly located at about 50 to 70 and 120 to 140 kin. Volumetric melt production rate changes spatially and episodically atop the slab, which may reflect the intensity and variations of volcanoes.

关键词： subduction water and melt three-dimensional model.