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World Journal of Gastroenterology 2011年第19期17卷 2372-2378页

作者： Wen-Ming Cong Hui Dong Lu Tan xu-xu sun Meng-Chao Wu Department of Pathology Eastern Hepatobiliary Surgery Hospital Second Military Medical University Shanghai 200438 China Department of Surgery Eastern Hepatobili- ary Surgery Hospital Second Military Medical University 225 Changhai Road Shanghai 200438 China

Accompanying rapid developments in hepatic surgery,the number of surgeries and identifications of histological types of primary hepatic space-occupying lesions (PHSOLs) have increased *** has led to many changes in the surgicopathological spectrum of PHSOLs,and has contributed to a theoretical basis for modern hepatic surgery and oncological *** 1982 and 2009 at the Eastern Hepatobiliary Surgery Hospital (EHBH) in Shanghai,31 901 patients underwent surgery and were diagnosed as having a *** this paper,we present an analysis of the PHSOL cases at the EHBH for this time period,along with results from a systematic literature *** describe a surgicopathological spectrum comprising more than 100 types of PHSOLs that can be stratified into three types:tumor-like,benign,and *** also stratified the PHSOLs into six subtypes derived from hepatocytes;cholangiocytes;vascular,lymphoid and hemopoietic tissues;muscular,fibrous and adipose tissues;neural and neuroendocrine tissues;and miscellaneous *** present study provides a new classification system that can be used as a current reference for clinicians and pathologists to make correct diagnoses and differential diagnoses among various PHSOLs.

关键词： Liver tumors Tumor-like lesions Pathology Immunohistochemistry Classification

A Methodology for Assessing Axial Compressor Stability with Inlet Temperature Ramp Distortion

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Journal of Thermal Science 2024年第3期33卷 856-871页

作者： sun Dakun GU Benhao NING Fangfei FANG Yibo DONG xu xu Dengke sun Xiaofeng School of Energy and Power Engineering Beihang UniversityBeijing102206China Research Institute of Aero-engine Beihang UniversityBeijing102206China

Based on a small perturbation stability model for periodic flow,the effects of inlet total temperature ramp distortion on the axial compressor are investigated and the compressor stability is quantitatively *** the beginning,a small perturbation stability model for the periodic flow in compressors is proposed,referring to the governing equations of the Harmonic Balance *** stability model is validated on a single-stage low-speed compressor TA36 with uniform inlet ***,the unsteady flow of TA36 with different inlet total temperature ramps and constant back pressure is simulated based on the Harmonic Balance *** on these simulations,the compressor stability is analyzed using the proposed small perturbation ***,the Dynamic Mode Decomposition method is employed to accurately extract pressure *** two parameters of the temperature ramp,ramp rate and Strouhal number,are discussed in this *** results indicate the occurrence and extension of hysteresis loops in the rows,and a decrease in compressor stability with increasing ramp *** performance is divided into two phases,stable and limit,based on the ramp ***,the model predictions suggest that a decrease in period length and an increase in Strouhal number lead to improved compressor *** DMD results imply that for compressors with inlet temperature ramp distortion,the increase of high-order modes and oscillations at the rotor tip is always the signal of decreasing stability.

关键词： axial compressor stability small perturbation model inlet temperature ramp distortion harmonic balance method dynamic mode decomposition method

Formation estimation and evolution mechanism of the pressure arch for non-circular tunnels under asymmetrical stress field

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Science China(Technological Sciences) 2024年第9期67卷 2919-2938页

作者： sun ZhenYu ZHANG DingLi xu Tong CHEN xu Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

The tunneling-induced stress redistribution is dependent on the tunnel shape and the in-situ stress field, and the previous arch characterization method based on the circumferential or maximum principal stresses is only suitable for the circular tunnels under the hydrostatic stress field. In this study, a unified characterization method of the pressure arch for non-circular tunnels under the arbitrary stress field is proposed. By comparing the variations of compressive stress in different directions due to excavation, the ratio of the most significant increase in compressive stress is presented to characterize the arch effect, and the corresponding numerical algorithm is given. Since the proposed method takes the stress element as the basic analytical model, it can be easily applied to various complex excavation situations. Thereafter, combined with the established folding catastrophic model, an objective and unified quantitative method of the pressure arch boundaries is given. Using the proposed method, the longitudinal evolution of the pressure arch is analyzed. According to the expansion rate of the arch boundaries, three evolution stages including the initial formation, rapid expansion and stabilization are categorized. Parametric studies are conducted to illustrate the effect of ground properties and support stiffness on the pressure arch formation. It is found that the ground strength parameters and burial depth affect the arch range at a decreasing rate, while they have little effect on the arch shape. The lateral pressure coefficient has a significant effect on both the shape and range of the pressure arch. Increasing the support stiffness helps reduce the pressure arch range with a decreasing rate, while the synchronous variation of the elastic moduli of the surrounding rock and support does not affect the arch range under a certain relative elastic modulus. Finally, field monitoring is conducted to validate the proposed method in actual support design.

关键词： pressure arch stress redistribution numerical simulation quantitative characterization longitudinal evolution parametric study

Adversarial data splitting for domain generalization

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Science China(Information Sciences) 2024年第5期67卷 28-42页

作者： Xiang GU Jian sun Zongben xu School of Mathematics and Statistics Xi'an Jiaotong University

Domain generalization aims to learn a model that is generalizable to an unseen target domain,which is a fundamental and challenging task in machine learning for out-of-distribution generalization. This paper proposes a novel domain generalization approach that enforces the learned model to be able to generalize well over the train/val subset splitting of the training dataset. This idea is modeled herein as an adversarial data splitting framework, formulated as a min-max optimization problem inspired by the metalearning approach. The min-max optimization problem is solved by iteratively splitting the training dataset into the training and val subsets to maximize the domain shift measured by the objective function and updating the model parameters to enable the model to generalize well from the training subset to the val subset by minimizing the objective function. This adversarial training approach does not assume the known domain labels of the training data; instead, it automatically investigates the “hard” splitting of the train/val subsets to learn the generalizable model. Extensive experimental results using three benchmark datasets demonstrate the superiority of this approach. In addition, we derive a generalization error bound for the theoretical understanding of our proposed approach.

关键词： domain generalization adversarial learning data splitting meta-learning out of distribution

Effect of fore/aft-loaded rotor on compressor stability under inlet circumferential distortion

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Chinese Journal of Aeronautics 2024年第5期37卷 199-213页

作者： Dakun sun Benhao GU Fangfei NING Dengke xu Xiaofeng sun School of Energy and Power Engineering Beihang UniversityBeijing 102206China Research Institute of Aero-engine Beihang UniversityBeijing 102206China

A modified small perturbation stability prediction model for axial compressors with circumferential inlet distortions is established and applied to investigate the effect of fore/aft-loaded rotor on compressor stability under circumferentially distorted inlet *** inlet total pressure distribution downstream of the distortion screen is measured in experiments and employed for simulations which are implemented via time-space spectral *** stall inception prediction results via the stability model indicate that the compressor with aft-loaded rotor not only performs better in terms of stability under uniform inlet,but also maintains a larger stability margin under circumferentially distorted *** experiments for compressors with fore-loaded and aft-loaded rotor are respectively carried *** results validate the reliability of numerical simulations and the predicted conclusion that the aft-loaded rotor is beneficial for compressor ***,the ability of the developed theoretical model for compressor stability prediction under circumferential distortions is *** addition,dynamic pressure signals at rotor tip measured in experiments illustrate that the circumferential distortion has little effect on the compressor stall pattern.

关键词： Axial compressor stability Inlet distortion Blade loading Small perturbation Time-space spectral method

Numerical study on the cavity dynamics for vertical water entries of twin spheres

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Defence Technology（防务技术） 2024年第2期32卷 459-472页

作者： xu Wang xujian Lyu Ruisheng sun Dongdong Tang School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing210094China Shanghai Institute of Spacecraft Equipment Shanghai200240China

In this study, a three dimensional(3D) numerical model of six-degrees-of-freedom(6DOF) is applied to simulate the water entries of twin spheres side-by-side at different lateral distances and time *** turbulence structure is described using the shear-stress transport k-ω(SST k-ω) model, and the volume of fluid(VOF) method is used to track the complex air-liquid interface. The motion of spheres during water entry is simulated using an independent overset grid. The numerical model is verified by comparing the cavity evolution results from simulations and experiments. Numerical results reveal that the time interval between the twin water entries evidently affects cavity expansion and contraction behaviors in the radial direction. However, this influence is significantly weakened by increasing the lateral distance between the two spheres. In synchronous water entries, pressure is reduced on the midline of two cavities during surface closure, which is directly related to the cavity volume. The evolution of vortexes inside the two cavities is analyzed using a velocity vector field, which is affected by the lateral distance and time interval of water entries.

关键词： Twin water entries Side-by-side Cavity Numerical simulation

Flower-like CuS/γ-Fe_(2)O_(3) van der Waals heterostructures with highefficient electromagnetic wave absorption

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Nano Research 2024年第4期17卷 3324-3333页

作者： Na Lu Jingshen xu Mengwei Yuan Genban sun Beijing Key Laboratory of Energy Conversion and Storage Materials Institution College of ChemistryBeijing Normal UniversityBeijing 100875China Center for Advanced Materials Research Beijing Normal UniversityZhuhai 519087China

The escalating electromagnetic(EM)pollution issues and the demand to elevate military stealth technology make it imperative to develop cost-effective and high-performance electromagnetic wave(EMW)absorbing *** this paper,the flower-like CuS/γ-Fe_(2)O_(3) van der Waals(vdW)heterostructures have been synthesized via a facile two-step solvothermal *** flower-like CuS skeleton increases the attenuation path of EMW while reducing the material *** contents ofγ-Fe_(2)O_(3) nanoparticles anchor between the flower-like CuS nanosheets to constitute a heterogeneous structure,which enables dielectric and magnetic loss synergistically to optimize impedance matching and remarkably improve the EMW absorption *** minimum reflection loss(RLmin)is-49.36 dB with a thickness of only 1.6 mm and the effective absorption bandwidth(EAB)reaches 4.64 GHz(13.36–18 GHz).By adjusting the thickness of the absorber,the EAB can cover 96%of the GHz ***,the superior absorption of-61.53 dB at middle frequency band can be obtained by adjusting the amount of Fe_(2)O_(3) *** this study,the adjustment of EM parameters and the optimization of impedance matching have been achieved by constructing a novel vdW heterogeneous structure,which provides fresh ideas and references for the design of high-performance EMW absorbing materials.

关键词： flower-like CuS γ-Fe_(2)O_(3) van der Waals heterostructures impedance matching electromagnetic wave absorption

Designing gradient nanograined dual-phase structure in duplex stainless steel for superior strength-ductility synergy

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Journal of Materials Science & Technology 2024年第3期170卷 122-128页

作者： Songsong xu Ying Han Jiapeng sun Guoqing Zu Mingkun Jiang Weiwei Zhu xu Ran Key Laboratory of Advanced Structural Materials Ministry of EducationChangchun University of TechnologyChangchun 130012China School of Materials Science and Engineering Changchun University of TechnologyChangchun 130012China Provincial Key Laboratory of Advanced Materials Processing and Application for Rail Transit Changchun University of TechnologyChangchun 130012China College of Mechanics and Materials Hohai UniversityNanjing 211100China

Similar to other metallic materials,duplex stainless steel dramatically loses its advantage of high ductility as they are ***,we produce a gradient nanograined dual-phase structure in the 2101 duplex stainless steel,thus facilitating a superior strength-ductility synergy:a yield strength of 1009.5 MPa being two times higher than that of the as-received sample,a total elongation of 23.4%and a uniform elongation of 5.9%.This novel structure is produced through a processing route of ultrasonic severe surface rolling and annealing,which realizes a superposition of gradient nanostructure and lamellar dual-phase structure with austenite and *** the tension deformation of gradi-ent nanograined dual-phase structured duplex stainless steel,a significant accumulation of geometrically necessary dislocations *** dislocations are formed to accommodate the deformation incompat-ibility caused by the layer-by-layer difference in strength and hardness of individual phase domains,as well as the inherent difference in properties between the austenite and ferrite *** results in a stronger hetero-deformation induced strengthening and hardening significantly contributing to superior mechanical *** study provides a new avenue to develop advanced steels with high strength and ductility.

关键词： Gradient structure Duplex stainless steel Synergetic strengthening Strength Ductility

Crystal facet-dependent CO_(2) cycloaddition to epoxides over ZnO catalysts

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Frontiers of Chemical Science and Engineering 2024年第5期18卷 49-59页

作者： Yongjian Wei Ying Li Yunfei xu Yinghui sun Tong xu Haiou Liang Jie Bai Inner Mongolia Key Laboratory of Industrial Catalysis Hohhot 010051China College of Chemical Engineering Inner Mongolia University of TechnologyHohhot 010051China

With regard to green chemistry and sustainable development,the fixation of CO_(2) into epoxides to form cyclic carbonates is an attractive and promising pathway for CO_(2) *** oxides,renowned as promising eco-friendly catalysts for industrial production,are often undervalued in terms of their impact on the CO_(2)addition *** this work,we successfully developed ZnO nanoplates with(002)surfaces and ZnO nanorods with(100)surfaces via morphology-oriented regulation to explore the effect of crystal faces on CO_(2) *** quantitative data obtained from electron paramagnetic resonance spectroscopy indicated that the concentration of oxygen vacancies on the ZnO nanoplate surfaces was more than twice that on the ZnO nanorod *** functional theory calculations suggested that the(002)surfaces have lower adsorption energies for CO_(2) and epichlorohydrin than the(100)*** a result,the yield of cyclochloropropene carbonate on the ZnO nanoplates(64.7%)was much greater than that on the ZnO nanorods(42.3%).Further evaluation of the reused catalysts revealed that the decrease in the oxygen vacancy concentration was the primary factor contributing to the decrease in catalytic *** on these findings,a possible catalytic mechanism for CO_(2) cycloaddition with epichlorohydrin was *** work provides a new idea for the controllable preparation of high-performance ZnO catalysts for the synthesis of cyclic carbonates from CO_(2) and epoxides.

关键词： carbon dioxide cycloaddition zinc oxide crystal face oxygen vacancy

Learning to sample initial solution for solving 0-1 discrete optimization problem by local search

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Science China Mathematics 2024年第6期67卷 1317-1340页

作者： Xin Liu Jianyong sun Zongben xu School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an710049China

Local search methods are convenient alternatives for solving discrete optimization problems(DOPs).These easy-to-implement methods are able to find approximate optimal solutions within a tolerable time *** is known that the quality of the initial solution greatly affects the quality of the approximated solution found by a local search *** this paper,we propose to take the initial solution as a random variable and learn its preferable probability *** aim is to sample a good initial solution from the learned distribution so that the local search can find a high-quality *** develop two different deep network models to deal with DOPs established on set(the knapsack problem)and graph(the maximum clique problem),*** deep neural network learns the representation of an optimization problem instance and transforms the representation to its probability *** results show that given the initial solution sampled from the learned probability distribution,a local search method can acquire much better approximate solutions than the randomly-sampled initial solution on the synthesized knapsack instances and the Erd?s-Rényi random graph ***,with sampled initial solutions,a classical genetic algorithm can achieve better solutions than a random initialized population in solving the maximum clique problems on DIMACS ***,we emphasize that the developed models can generalize in dimensions and across graphs with various densities,which is an important advantage on generalizing deep-learning-based optimization algorithms.

关键词： discrete optimization deep learning graph convolutional network local search