A tournament is an orientation of the edges of a complete graph.An arc in a digraph D is pancyclic if it is contained in a cycle of length k for every 3≤k≤|V(D)|.An arc uv in a digraph D is k-anticyclic if there is ...A tournament is an orientation of the edges of a complete graph.An arc in a digraph D is pancyclic if it is contained in a cycle of length k for every 3≤k≤|V(D)|.An arc uv in a digraph D is k-anticyclic if there is a path from u to v of length k-1 in D.If for every3≤k≤|V(D)|,an arc uv is k-anticyclic,then we say that uv is anti-pancyclic in D.It has been proved in Discrete Appl.Math.79(1997)127-135 that every arc of a 3-strong and arc-3-cyclic tournament T is k-anticyclic for each k≥4,unless T is isomorphic to two tournaments,each of which has exactly 8 vertices.In J.Combin.Inform.System Sci.19(1994)207-214,Moon showed that every strong tournament contains at least three pancyclic arcs and characterized the tournaments that attain this lower bound.In this paper we investigate the number of antipancyclic arcs in strong tournaments and show that every strong tournament with order n≥6contains at least four anti-pancyclic arcs unless it is isomorphic to five tournaments,each of which has exactly 6 vertices.Consequently,every strong tournament with order n≥7 contains at least four anti-pancyclic arcs.展开更多
The electric arc furnace(EAF)offers advantages in energy savings,environmental protection,and high efficiency by using scrap as the primary charge and utilizing a high-temperature electric arc as the main heat source ...The electric arc furnace(EAF)offers advantages in energy savings,environmental protection,and high efficiency by using scrap as the primary charge and utilizing a high-temperature electric arc as the main heat source for steel smelting.The improvement of EAF smelting efficiency is primarily influenced by three key factors:the heat transfer efficiency of the electric arc,the intensity of molten pool stirring,and the melting rate of scrap.The arc heat transfer efficiency determines the energy input efficiency and the maximum smelting temperature of the EAF.Molten pool stirring intensity plays a crucial role in ensuring uniformity in temperature,composition,and flow within the furnace,preventing the formation of dead zones.The scrap melting rate is a decisive factor in EAF smelting efficiency,largely governed by the coupling of heat and mass transfer.Thus,understanding not only the rapid melting mechanism of scrap but also the impact of arc heat transfer and molten pool stirring is essential to optimizing the smelting process.Advancing research in these areas is critical for shortening the EAF smelting cycle,reducing energy consumption,lowering costs,and improving resource utilization.Therefore,recent achievements and development trends in fundamental research on enhancing EAF smelting efficiency were summarized.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
为探讨ARC菌肥对提高花生产量和降镉的可能性,本研究以阜花40为试验材料,采用小区试验,以单独施用复合肥为对照,分析ARC菌肥不同施用量对花生产量和降镉效果的影响。结果表明,随着ARC微生物菌肥施用量的增加,花生产量增幅15.84%~25.31%,...为探讨ARC菌肥对提高花生产量和降镉的可能性,本研究以阜花40为试验材料,采用小区试验,以单独施用复合肥为对照,分析ARC菌肥不同施用量对花生产量和降镉效果的影响。结果表明,随着ARC微生物菌肥施用量的增加,花生产量增幅15.84%~25.31%,且A3(每亩施用6 kg ARC菌肥)和A4(每亩施用8 kg ARC菌肥)处理产量最高,但两处理间差异不显著。在花生籽仁镉含量的测定中发现,A3和A4处理降镉效果最好,但2处理间差异不显著。综上所述,A3处理是本试验条件下兼顾花生产量提升和降镉效果的最优处理方案,该处理不仅能够有效提高花生产量,还能显著降低花生籽仁镉含量,达到理想的降镉效果,同时在成本控制方面具有明显优势,适合在花生生产中推广应用。展开更多
This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the i...This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the increase of light amplitude;(Ⅳ)Formalism for light-induced anomalous Hall effects.展开更多
电弧定向能量沉积(arc-based directed energy deposition,Arc-DED)技术在铝合金结构制造领域的地位日益凸显,具备独特优势与应用潜力。然而,由于铝合金的自身理化特性,热沉积过程极易产生氧化、变形、气孔等问题。同时,沉积过程的热量...电弧定向能量沉积(arc-based directed energy deposition,Arc-DED)技术在铝合金结构制造领域的地位日益凸显,具备独特优势与应用潜力。然而,由于铝合金的自身理化特性,热沉积过程极易产生氧化、变形、气孔等问题。同时,沉积过程的热量累积效应,可进一步增加沉积结构出现裂纹、形状塌陷和残余应力等问题的概率,严重制约了铝合金Arc-DED制造质量与生产效率的提升,极大限制了铝合金Arc-DED结构在相关工业领域的推广应用。围绕现代工业对铝合金Arc-DED提质增效提出的更高要求,从沉积过程的前、中、后三方面综述了优化能量输入、添加变质剂、引入辅助能场以及热处理等重要技术手段,分析了各类方法的优缺点和适用范围,并探讨了铝合金Arc-DED技术的未来发展方向,为平衡铝合金高性能构件生产制造的质效矛盾、推动铝合金Arc-DED技术高速发展提供了重要的理论指引与实践参考。展开更多
基金Supported by the National Natural Sciences Foundation for Young Scientists of China(11701349)the Natural Science Foundation of Shanxi Province,China(202203021211318,202103021224019)。
文摘A tournament is an orientation of the edges of a complete graph.An arc in a digraph D is pancyclic if it is contained in a cycle of length k for every 3≤k≤|V(D)|.An arc uv in a digraph D is k-anticyclic if there is a path from u to v of length k-1 in D.If for every3≤k≤|V(D)|,an arc uv is k-anticyclic,then we say that uv is anti-pancyclic in D.It has been proved in Discrete Appl.Math.79(1997)127-135 that every arc of a 3-strong and arc-3-cyclic tournament T is k-anticyclic for each k≥4,unless T is isomorphic to two tournaments,each of which has exactly 8 vertices.In J.Combin.Inform.System Sci.19(1994)207-214,Moon showed that every strong tournament contains at least three pancyclic arcs and characterized the tournaments that attain this lower bound.In this paper we investigate the number of antipancyclic arcs in strong tournaments and show that every strong tournament with order n≥6contains at least four anti-pancyclic arcs unless it is isomorphic to five tournaments,each of which has exactly 6 vertices.Consequently,every strong tournament with order n≥7 contains at least four anti-pancyclic arcs.
基金supported by National Key R&D Program of China(Grant No.2022YFC3901403)China Baowu Low Carbon Metallurgy Innovation Foundation(Grant No.BWLCF202211)Program of Introducing Talents of Discipline to Universities(Grant No.B21001).
文摘The electric arc furnace(EAF)offers advantages in energy savings,environmental protection,and high efficiency by using scrap as the primary charge and utilizing a high-temperature electric arc as the main heat source for steel smelting.The improvement of EAF smelting efficiency is primarily influenced by three key factors:the heat transfer efficiency of the electric arc,the intensity of molten pool stirring,and the melting rate of scrap.The arc heat transfer efficiency determines the energy input efficiency and the maximum smelting temperature of the EAF.Molten pool stirring intensity plays a crucial role in ensuring uniformity in temperature,composition,and flow within the furnace,preventing the formation of dead zones.The scrap melting rate is a decisive factor in EAF smelting efficiency,largely governed by the coupling of heat and mass transfer.Thus,understanding not only the rapid melting mechanism of scrap but also the impact of arc heat transfer and molten pool stirring is essential to optimizing the smelting process.Advancing research in these areas is critical for shortening the EAF smelting cycle,reducing energy consumption,lowering costs,and improving resource utilization.Therefore,recent achievements and development trends in fundamental research on enhancing EAF smelting efficiency were summarized.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
文摘为探讨ARC菌肥对提高花生产量和降镉的可能性,本研究以阜花40为试验材料,采用小区试验,以单独施用复合肥为对照,分析ARC菌肥不同施用量对花生产量和降镉效果的影响。结果表明,随着ARC微生物菌肥施用量的增加,花生产量增幅15.84%~25.31%,且A3(每亩施用6 kg ARC菌肥)和A4(每亩施用8 kg ARC菌肥)处理产量最高,但两处理间差异不显著。在花生籽仁镉含量的测定中发现,A3和A4处理降镉效果最好,但2处理间差异不显著。综上所述,A3处理是本试验条件下兼顾花生产量提升和降镉效果的最优处理方案,该处理不仅能够有效提高花生产量,还能显著降低花生籽仁镉含量,达到理想的降镉效果,同时在成本控制方面具有明显优势,适合在花生生产中推广应用。
文摘This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the increase of light amplitude;(Ⅳ)Formalism for light-induced anomalous Hall effects.
文摘电弧定向能量沉积(arc-based directed energy deposition,Arc-DED)技术在铝合金结构制造领域的地位日益凸显,具备独特优势与应用潜力。然而,由于铝合金的自身理化特性,热沉积过程极易产生氧化、变形、气孔等问题。同时,沉积过程的热量累积效应,可进一步增加沉积结构出现裂纹、形状塌陷和残余应力等问题的概率,严重制约了铝合金Arc-DED制造质量与生产效率的提升,极大限制了铝合金Arc-DED结构在相关工业领域的推广应用。围绕现代工业对铝合金Arc-DED提质增效提出的更高要求,从沉积过程的前、中、后三方面综述了优化能量输入、添加变质剂、引入辅助能场以及热处理等重要技术手段,分析了各类方法的优缺点和适用范围,并探讨了铝合金Arc-DED技术的未来发展方向,为平衡铝合金高性能构件生产制造的质效矛盾、推动铝合金Arc-DED技术高速发展提供了重要的理论指引与实践参考。
