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Improved Upper Bounds on Acyclic Edge Colorings

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Acta Mathematicae Applicatae Sinica 2014年第2期30卷 305-308页

作者： yu-wen wu Gui-ying YAN School of Information Beijing Wuzi University Academy of Mathematics and Systems Science Chinese Academy of Sciences

An acyclic edge coloring of a graph is a proper edge coloring such that every cycle contains edges of at least three distinct colors. The acyclic chromatic index of a graph G, denoted by a＇（G）, is the minimum number k such that there is an acyclic edge coloring using k colors. It is known that a＇（G） ≤ 16△ for every graph G where △denotes the maximum degree of G. We prove that a＇（G）〈 13.8A for an arbitrary graph G. We also reduce the upper bounds of a＇（G） to 9.8△ and 9△ with girth 5 and 7, respectively.

关键词： graph coloring acyclic edge coloring Lovasz local lemma

Experimental research on the instability propagation characteristics of liquid kerosene rotating detonation wave

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Defence Technology（防务技术） 2020年第6期16卷 1106-1115页

作者： Quan Zheng Hao-long Meng Chun-sheng weng yu-wen wu wen-kang Feng Ming-liang wu National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094China

In order to study the instability propagation characteristics of the liquid kerosene rotating detonation wave(RDW),a series of experimental tests were carried out on the rotating detonation combustor(RDC)with *** fuel and oxidizer are room-temperature liquid kerosene and preheated oxygenenriched air,*** experimental tests keep the equivalence ratio of 0.81 and the oxygen mass fraction of 35%unchanged,and the total mass flow rate is maintained at about 1000 g/s,changing the total temperature of the oxygen-enriched air from 620 K to 860 *** different types of instability were observed in the experiments:temporal and spatial instability,mode transition and *** interaction between RDW and supply plenum may be the main reason for the fluctuations of detonation wave velocity and pressure peaks with ***,the inconsistent mixing of fuel and oxidizer at different circumferential positions is related to RDW oscillate *** phenomenon of single-double-single wave transition is *** the transition,the initial RDW weakens until disappears,and the compression wave strengthens until it becomes a new RDWand propagates *** increased deflagration between the detonation products and the fresh gas layer caused by excessively high temperature is one of the reasons for the RDC quenching and re-initiation.

关键词： Rotating detonation wave Liquid kerosene Oxygen-enriched air Instability propagation characteristics Compression wave

Influence of propagation direction on operation performance of rotating detonation combustor with turbine guide vane

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Defence Technology（防务技术） 2021年第5期17卷 1617-1624页

作者： Wan-li Wei yu-wen wu Chun-sheng weng Quan Zheng National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094China

Due to the pressure gain combustion characteristics,the rotating detonation combustor(RDC)can enhance thermodynamic cycle ***,the performance of gas-turbine engine can be further improved with this combustion *** the present study,the RDC operation performance with a turbine guide vane(TGV)is experimentally *** and air are used as propellants while hydrogen and air mass flow rate are about 16.1 g/s and 500 g/s and the equivalence ratio is about 1.0.A pre-detonator is used to ignite the ***-frequency dynamic pressure transducers and silicon pressure sensors are employed to measure pressure oscillations and static pressure in the combustion *** experimental results show that the steady propagation of rotating detonation wave(RDW)is observed in the combustion chamber and the mean propagation velocity is above 1650 m/s,reaching over 84%of theoretical Chapman-Jouguet detonation *** and counterclockwise propagation directions of RDW are *** clockwise propagation direction,the static pressure is about 15%higher in the combustor compared with counterclockwise propagation direction,but the RDW dominant frequency is *** the oblique shock wave propagates across the TGV,the pressure oscillations reduces *** addition,as the detonation products flow through the TGV,the static pressure drops up to 32%and 43%for clockwise and counterclockwise propagation process respectively.

关键词： Rotating detonation combustor Propagation direction Turbine guide vane Operation performance

Improved Bounds on the Generalized Acyclic Chromatic Number

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Acta Mathematicae Applicatae Sinica 2016年第1期32卷 67-72页

作者： yu-wen wu Kan-ran TAN Gui-ying YAN Beijing wuzi University Beijing 101149China Johns Hopkins University BaltimoreMarylandUnited States of America Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100080China

An r-acyclic edge chromatic number of a graph G,denoted by α＇r（G）,is the minimum number of colors used to produce an edge coloring of the graph such that adjacent edges receive different colors and every cycle C has at least min {｜C｜,r} *** prove that α＇r（G） ≤（4r ＋ 1）△（G）,when the girth of the graph G equals to max{50,△A（G）} and 4 ≤ r ≤ *** we relax the restriction of the girth to max {220,A（G）},the upper bound of a＇r（G） is not larger than（2r ＋ 5）△（G） with 4 ≤r≤ 10.

关键词： edge coloring r-acyclic edge coloring grith Lovasz local lemma

Artificial Neural Network Modeling of Microstructure During C-Mn and HSLA Plate Rolling

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Journal of Iron and Steel Research International 2009年第2期16卷 80-83页

作者： TAN wen LIU Zhen-yu wu Di WANG Guo-dong The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

An artificial neural network （ANN） model for predicting transformed mierostrueture in conventional rolling process and therrnomechanical controlled process （TMCP） is proposed. The model uses austenite grain size and retained strain, which can be calculated by using microstructure evolution models, together with a measured cooling rate and chemical compositions as inputs and the ferrite grain size and ferrite fraction as outputs. The predicted re- suits show that the model can predict the transformed microstructure which is in good agreement with the measured one, and it is better than the empirical equations. Also, the effect of the alloying elements on transformed products has been analyzed by using the model. The tendency is the same as that in the reported articles. The model can be used further for the optimization of processing parameters, mierostructure and properties in TMCP.

关键词： artificial neural network TMCP microstructure ferrite grain size

Using a pre-kicker to ensure safe extractions from the HEPS storage ring

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Nuclear Science and Techniques 2021年第12期32卷 26-36页

作者： Zhe Duan Jin-Hui Chen Hua Shi Guang-Yi Tang Lei Wang yu-wen wu Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Dongguan Neutron Science Center Dongguan 523800China

The High Energy Photon Source(HEPS)is a 6 GeV diffraction-limited storage ring light source under *** swap-out injection is adopted with the depleted bunch recycled via high-energy accumulation in the *** extremely high beam energy density of the bunches with an ultra-low emittance(about 30 pm horizontally and 3 pm vertically)and high bunch charges(from 1.33 to 14.4 nC)extracted from the storage ring could cause hazardous damage to the extraction Lambertson magnet in case of extraction kicker *** this end,we proposed the use of a pre-kicker to spoil the bunches prior to extraction,significantly reducing the maximum beam energy density down to within a safe region while still maintaining highly efficient *** main parameters of the pre-kicker are simulated and discussed.

关键词： Pre-kicker The high energy photon source Intense electron beam Diffraction-limited storage ring Extraction Lambertson magnet

Effects of total pressures and equivalence ratios on kerosene/air rotating detonation engines using a paralleling CE/SE method

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Defence Technology（防务技术） 2021年第6期17卷 1805-1816页

作者： Fang Wang Chun-sheng weng yu-wen wu Qiao-dong Bai Quan Zheng Han Xu National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094China

In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation,instabilities,and propulsive performance.A hybrid MPI t OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC)systems.A series of cases with the total pressure of 1 MPa,1.5 MPa,2 MPa,and the equivalence ratio of 0.9,1,1.4 are *** one hand,the total pressure shows a significant impact on the instabilities of rotating detonation *** instability phenomenon is observed in cases with low total pressure(1 MPa)and weakened with the increase of the total *** total pressure has a small impact on the detonation wave velocity and the specific *** the other hand,the equivalence ratio shows a negligible influence on the instabilities,while it affects the ignition process and accounts for the detonation velocity *** is more difficult to initiate rotating detonation waves directly in the lean fuel operation *** difference was observed in the thrust with different equivalence ratios of 0.9,1,and *** highest specific impulse was obtained in the lean fuel cases,which is around 2700 *** findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.

关键词： Kerosene/air rotating detonation waves Total pressure Equivalence ratio Instabilities MPItOpenMP

Effect of BaO and MgO on structure and properties of aluminate slag with various CaO/Al_(2)0_(3)ratios

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Journal of Iron and Steel Research International 2024年第1期31卷 204-214页

作者： yu-qi Kong Ting wu wen-zhi Xia wen Yang Hai-chuan Wang School of Metallurgical Engineering Anhui University of TechnologyMa’anshan243032AnhuiChina Key Laboratory of Metallurgical Emission Reduction and Resource Recycling(Ministry of Education) Anhui University of TechnologyMa’anshan243002AnhuiChina

To provide theoretical guidance for performance stability control of low-reactive mold fluxes,the effects of BaO and MgO on the structure and properties of aluminate slag with various CaO/Al_(2)0_(3)(C/A)ratios were investigated using the Fourier transform infrared spectrometer,Raman spectroscope,hemispherical melting point instrument,rotational viscometer and X-ray *** results indicated that with BaO and MgO addition,the structure polymerization was first weakened and then enhanced at C/A of 1.1,and the transition contents corresponded to 8 wt.%BaO and 2 wt.%MgO,respectively,while the structure polymerization decreased continuously at C/A of *** the viscosity change was well consistent with the structure evolution,the polymerization degree played a more prominent role in the slag viscosity than superheat degree when the melting temperature difference was within 40℃.The break temperature decreased initially and then increased with augment of BaO and MgO at C/A of 1.1,while it manifested a decrease trend with BaO addition,and it decreased obviously but then turned to increase with MgO increment at C/A of *** crystallization phase and crystallization ratio kept stable with BaO increment,while the crystallization ratio rose greatly with MgO promoting LiAlO_(2)precipitation at C/A of *** crystal types of all experimental slags were mainly Ca_(12)Al_(14)O_(33)and CaF_(2)at C/A of 1.3,and the precipitation of crystalline phase BaAl2O4 demonstrated a rising trend,while that of Ca_(12)Al_(14)O_(33)gradually declined with BaO augment.

关键词： Aluminate slag Structure MgO BaO Viscosity Property

A regression approach for seismic first-break picking

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Petroleum Science 2024年第3期21卷 1584-1596页

作者： Huan yuan San-Yi yuan Jie wu wen-Jing Sang yu-He Zhao CNPC Key Laboratory of Geophysical Exploration China University of Petroleum(Beijing)Beijing 102249China Research Institute of Petroleum Exploration&Development—Northwest(NWGI) Key Laboratory of reservoir characterization of CNPCPetroChinaLanzhou 730020GansuChina

The picking efficiency of seismic first breaks(FBs)has been greatly accelerated by deep learning(DL)***,the picking accuracy and efficiency of DL methods still face huge challenges in low signal-to-noise ratio(SNR)*** address this issue,we propose a regression approach to pick FBs based on bidirectional long short-term memory(Bi LSTM)neural network by learning the implicit Eikonal equation of 3D inhomogeneous media with rugged topography in the target *** employ a regressive model that represents the relationships among the elevation of shots,offset and the elevation of receivers with their seismic traveltime to predict the unknown FBs,from common-shot gathers with sparsely distributed *** from image segmentation methods which automatically extract image features and classify FBs from seismic data,the proposed method can learn the inner relationship between field geometry and *** addition,the predicted results by the regressive model are continuous values of FBs rather than the discrete ones of the binary *** picking results of synthetic data shows that the proposed method has low dependence on label data,and can obtain reliable and similar predicted results using two types of label data with large *** picking results of9380 shots for 3D seismic data generated by vibroseis indicate that the proposed method can still accurately predict FBs in low SNR *** subsequent stacked profiles further illustrate the reliability and effectiveness of the proposed *** results of model data and field seismic data demonstrate that the proposed regression method is a robust first-break picker with high potential for field application.

关键词： First-break picking Low signal-to-noiseratio Regression BiLSTM Traveltime Geometry Noisy seismic data