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Fault-tolerant hamiltonian cycles and paths embedding into locally exchanged twisted cubes

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Frontiers of Computer Science 2021年第3期15卷 59-74页

作者： weibei fan Jianxi fan Zhijie HAN Peng LI Yujie ZHANG Ruchuan WANG College of Computer Nanjing University of Posts and TelecommunicationsNanjing 210023China School of Computer Science and Technology Soochow UniversitySuzhou 215006China Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks Jiangsu ProvinceNanjing 210003China

The foundation of information society is computer interconnection network,and the key of information exchange is communication algorithm.Finding interconnection networks with simple routing algorithm and high fault-tolerant performance is the premise of realizing various communication algorithms and protocols.Nowadays,people can build complex interconnection networks by using very large scale integration(VLSI)technology.Locally exchanged twisted cubes,denoted by(s+t+1)-dimensional LeTQ_(s,t) which combines the merits of the exchanged hypercube and the locally twisted cube.It has been proved that the LeTQ_(s,t) has many excellent properties for interconnection networks,such as fewer edges,lower overhead and smaller diameter.Embeddability is an important indicator to measure the performance of interconnection networks.We mainly study the fault tolerant Hamiltonian properties of a faulty locally exchanged twisted cube,LeTQ_(s,t)-(f_(v)+f_(e)),with faulty vertices f_(v) and faulty edges fe.Firstly,we prove that an LeTQ_(s,t) can tolerate up to s-1 faulty vertices and edges when embedding a Hamiltonian cycle,for s≥2,t≥3,and s≤t.Furthermore,we also prove another result that there is a Hamiltonian path between any two distinct fault-free vertices in a faulty LeTQ_(s,t) with up to(s-2)faulty vertices and edges.That is,we show that LeTQ_(s,t) is(s-1)-Hamiltonian and(s-2)-Hamiltonian-connected.The results are proved to be optimal in this paper with at most(s-1)-fault-tolerant Hamiltonicity and(s-2)fault-tolerant Hamiltonian connectivity of LeTQ_(s,t).

关键词： interconnection network fault-tolerant LeTQ_(s,t) hamiltonian cycle hamiltonian path

分层立方体网络在NoC线性阵列中的最优嵌入

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计算机科学 2023年第4期50卷 249-256页

作者：过汝燕王岩樊建席樊卫北苏州大学计算机科学与技术学院江苏苏州215006 南京邮电大学计算机学院南京210003

随着大数据时代的到来,大规模计算的需求使得人们对芯片性能的要求日益提高,片上网络(Network-on-Chip,NoC)作为芯片内部以网络通信为中心的互连结构,在通信的各个方面实现了良好的平衡。NoC组件的物理布局及互连方式对芯片的总体性能(... 详细信息

随着大数据时代的到来,大规模计算的需求使得人们对芯片性能的要求日益提高,片上网络(Network-on-Chip,NoC)作为芯片内部以网络通信为中心的互连结构,在通信的各个方面实现了良好的平衡。NoC组件的物理布局及互连方式对芯片的总体性能(如信号延迟、电路成本等)有着很大的影响,因芯片面积有限,最小化连接组件的导线总长度,即最小化线长,被作为芯片设计的重点。分层立方体网络(Hierarchical Cubic Network,HCN)具有通信延迟低、可靠性和扩展性高等优点,而线性阵列是NoC常用的拓扑结构之一,将分层立方体网络移植到线性阵列上,就可以在线性阵列上模拟分层立方体网络的结构和算法。图嵌入是实现网络移植的关键技术。在图嵌入中,最小化导线总长度的目标可以通过求解具有最小线长的最优嵌入来达成。文中主要研究了分层立方体网络在线性阵列中的最优嵌入问题。首先,通过研究分层立方体网络的最优集,提出了分层立方体网络在线性阵列中的一种嵌入方案hel,并证明在嵌入方案hel下的线长相比其他嵌入方案下的线长是最小的,即hel为最优嵌入;然后给出了嵌入hel下线长的精确值以及一个时间复杂度为O(N)的嵌入算法,其中N为n维分层立方体网络的顶点数且N=22n;其次,还给出了分层立方体网络在NoC上的线性物理布局算法;最后,通过对比实验评估了嵌入hel的性能。

关键词：片上网络图嵌入线长分层立方体网络线性阵列

A progressive framework for rotary motion deblurring

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Defence Technology（防务技术） 2024年第2期32卷 159-172页

作者： Jinhui Qin Yong Ma Jun Huang fan fan You Du School of Electronic Information Wuhan UniversityWuhan430072China

The rotary motion deblurring is an inevitable procedure when the imaging seeker is mounted in the rotating missiles.Traditional rotary motion deblurring methods suffer from ringing artifacts and noise,especially for large blur extents.To solve the above problems,we propose a progressive rotary motion deblurring framework consisting of a coarse deblurring stage and a refinement stage.In the first stage,we design an adaptive blur extents factor(BE factor)to balance noise suppression and details reconstruction.And a novel deconvolution model is proposed based on BE factor.In the second stage,a triplescale deformable module CNN(TDM-CNN)is designed to reduce the ringing artifacts,which can exploit the 2D information of an image and adaptively adjust spatial sampling locations.To establish a standard evaluation benchmark,a real-world rotary motion blur dataset is proposed and released,which includes rotary blurred images and corresponding ground truth images with different blur angles.Experimental results demonstrate that the proposed method outperforms the state-of-the-art models on synthetic and real-world rotary motion blur datasets.The code and dataset are available at https://***/JinhuiQin/RotaryDeblurring.

关键词： Rotary motion deblurring Progressive framework Blur extents factor TDM-CNN

Impact of non-ideal UE hardware on cell-free massive MIMO network with centralized operation

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Science China(Information Sciences) 2024年第4期67卷 255-271页

作者： Ning LI Pingzhi fan Institute of Mobile Communications Southwest Jiaotong University

This paper investigates the impact of non-ideal user equipment(UE) hardware on a cell-free(CF) massive MIMO(mMIMO) network with centralized operation under spatially correlated channels. The minimum mean-squared error(MMSE) estimator can be derived with the help of the generic non-ideal UE hardware model. It is demonstrated that even if the effective signal-to-noise ratio approaches infinity, pilot contamination and imperfect hardware can cause a non-zero estimation error floor. After that, a lower bound is determined for the ergodic uplink capacity of the centralized CF mMIMO network under non-ideal UE hardware. Moreover, the optimal receive combining vector is obtained to maximize the uplink spectral efficiency(SE). The maximum ratio(MR) and regularized zero-forcing(RZF) combining schemes are offered as alternatives in light of the computational complexity of the MMSE receiver. Comparing the RZF to the MMSE scheme under different levels of hardware impairments, our findings indicate that the RZF receiver suffers a negligible loss in total SE. For MR combining, a novel closed-form uplink achievable SE expression is obtained based on the MMSE estimator and the use-and-then-forget bounding technique. This expression gives vital insights into the achievable uplink performance with UE hardware impairments. Besides, for various hardware impairment factors, the impact of pilot sequence length on average sum SE is disclosed for different receive combining schemes. To increase the overall SE of the max-min fairness scheme, a heuristic fractional power control scheme with UE hardware impairments is developed, which can essentially avoid sacrificing the SE of other UEs while maximizing the SE of the unluckiest UE in the whole network. Finally,our theoretical performance analysis and power control algorithm are validated by simulation results, and fundamental design guidelines are provided for selecting hardware satisfying the practical UE requirements.

关键词： cell-free massive MIMO centralized operation spatially correlated channels hardware impairments channel estimation uplink spectral efficiency optimal receive combining pilot length design fractional power control

Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction:Efficient photodegradation of organic pollutant and toxicity evaluation

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Journal of Materials Science & Technology 2024年第3期170卷 200-211页

作者： Yanyan Zhao Xu fan Hongxing Zheng Enzhou Liu Jun fan Xuejun Wang College of Biology Pharmacy and Food Engineering Shangluo UniversityShangluo 726000China QinLing-Bashan Mountains Bioresources Comprehensive Development C.I.C. Shaanxi University of TechnologyHanzhong 723001China School of Chemical Engineering Northwest UniversityXi’an 710069China

Constructing of heterojunction was identified as a feasible way to improve photocatalytic activity of pho-tocatalyst.In this work,a n-p type Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was successfully prepared for organic pollutants degradation.This Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction exhibited much higher pho-tocatalytic activity towards Rhodamine B(92.24%,expose to visible light for 60 min),norfloxacin(81.73%,expose to visible light for 90 min)and levofloxacin(87.46%,expose to visible light for 90 min)than pure Bi_(2)WO_(6)and pure AgInS_(2).Toxicity analysis indicated the low environmental toxicity of Rhodamine B degradation intermediates for Rye seeds and Sudangrass seeds germination and growth.Mechanism study displayed that AgInS_(2)and Bi_(2)WO_(6)work as the primary photocatalyst to form·O_(2)−and ·OH,respectively.The improved photocatalytic activity of the Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was due to the im-proved light response range and intensified carrier separation capability.Additionally,a S-scheme charge transfer mechanism including multiple charge transfer channels was proposed.This work could provide an effective strategy for organic pollutants degradation in wastewater.

关键词： Photocatalysis S-scheme heterojunction AgInS_(2) Bi_(2)WO_(6) Toxicity experiments

Soliton resolution and asymptotic stability of N-solutions for the defocusing Kundu–Eckhaus equation with nonzero boundary conditions

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Communications in Theoretical Physics 2024年第1期76卷 1-6页

作者： Engui fan Yanxi Zhang School of Mathematical Sciences and Key Laboratory of Mathematics for Nonlinear Science Fudan UniversityShanghai200433China Tianjin Xinhua High School No.99 machang RoadTianjin300204China

In this paper,we address interesting soliton resolution,asymptotic stability of N-soliton solutions and the Painleve asymptotics for the Kundu-Eckhaus(KE)equation with nonzero boundary conditions iq_(t)+q_(xx)-2(l|q|^(2)-1)q+4β^(2)(lql^(4)-1)q+4iβ(lql^(2))_(x)q=0,q(x,0)=q_(0)(x)-±1,x→±∞.The key to proving these results is to establish the formulation of a Riemann-Hilbert(RH)problem associated with the above Cauchy problem and find its connection with the RH problem of the defocusing NLS equation.With the■-steepest descent method and the results of the defocusing NLS equation,we find complete leading order approximation formulas for the defocusing KE equation on the whole(x,t)half-plane including soliton resolution and asymptotic stability of N-soliton solutions in a solitonic region,Zakharov-Shabat asymptotics in a solitonless region and the Painlevéasymptotics in two transition regions.

关键词： defocusing Kundu-Eckhaus equation Riemann-Hilbert problems steepest descent method soliton resolution asymptotic stability Painleve transcendents

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 184-194页

作者： Ruiying Zhang fan Jiang Long Xue School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Academy of Safety Engineering and Technology Beijing 102617China College of Mechanical and Energy Engineering Beijing University of TechnologyBeijing 100124China

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive manufacturing.In this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial direction.The results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was expanded.When the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting amount.The average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc power.The minimum melting amount was not affected by the wire-torch distance under any current separation ratio tested.When the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch distance.When the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch distance.The effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation ratio.Through this study,the decoupling mechanism and ability of this innovative arc heat source is more clearly.

关键词： Twin-body plasma arc Melting control ability Melting amount Current separation ratio

Flow instability of supercritical hydrocarbon fuel in a multi-channel cooling system

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Chinese Journal of Aeronautics 2024年第2期37卷 283-295页

作者： Yichao JIN Kun WU Xuejun fan Institute of Applied Physics and Computational Mathematics Beijing 100094China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Thermally-induced flow instabilities are a critical issue in multi-channel regenerative cooling systems.In particular,the interactions between Density-Wave Oscillations(DWO)and Flow Maldistribution(FMD)can result in complex and disastrous instability phenomena.This study investigates the instability behaviors of hydrocarbon fluid in a four-channel system with a constant heat flux ratio using both frequency-and time-domain methods.As the heat flux increases,the in-tube flow sequentially destabilizes in each channel and converges to new equilibrium states,leading to the emergence of FMD phenomena.This also causes the system eigenvalue to change repeatedly from negative to positive rather than increasing monotonically.Additionally,the system eigenvalues are between those of the two most unstable channels,indicating that the stability behavior of the entire system is dictated by the most unstable channel.After FMD occurs,flow oscillations are activated in channels with weak stability,and the in-tube flow is observed to evolve into various flow patterns,including stable flow,self-sustained oscillation,oscillation divergence,quasiperiodic oscillation,and oscillation excursion.The novel instability mode of oscillation excursion involves a spontaneous transition of operating states.It oscillates from an equilibrium state and then stabilizes at a new operational state after oscillation-induced redistribution.However,the newfound stable state may also be only temporary,with the in-tube flow regressing to the initial state,resulting in quasi-periodic oscillation.

关键词： Cooling Supercritical fluids Hydrocarbons Flow instability Flow maldistribution Density-wave oscillations

Processing,microstructure,and properties of porous ceramic composites with directional channels

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Journal of Materials Science & Technology 2024年第1期168卷 1-15页

作者： Bo Zhang Yang Yang Xueling fan Key Laboratory of Service Performance and Protection Technology in Extreme Environments Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China

Porous ceramic composites with directional microchannels from micrometer to dozens of micrometer levels have attracted more and more attention in various fields including aerospace,biomedicines,and thermal insulation due to their excellent fluid permeability,mechanical properties,etc.In this article,we summarize the recent directional porous ceramics developments including their main processing routes and respective properties.Meanwhile,the properties get from different processing routes have been com-pared and analyzed in terms of microstructures,mechanical properties,and permeability.Emphasis has been given to the deeper understanding which can allow one to control the microstructural features of these porous ceramic composites to obtain the desired characteristics.This work can provide a useful reference for the development and application of porous ceramic composites with directional microchan-nels.

关键词： Porous ceramic composites Directional microchannels Processing routes Permeability