Mutual effects between a gliding arc discharge and a premixed flame

Mutual effects between a gliding arc(GA)discharge at atmospheric pressure and a premixed CH_(4)/air flame were experimentally investigated.Effects of the flame on the GA were studied using simultaneous measurements of the current,the voltage,and the instantaneous images of the plasma columns.The GA in the flame has a thicker and more diffusive plasma column,and it is more frequently ignited at a smaller breakdown voltage than that in the air.The GA extension velocity and the gliding velocity in the flame are larger than those in the air.The electrode voltage drop of the GA discharge in the flame is about 160 V,whereas that in the air is about 220 V.Compared with the GA in the air,the different features of the GA in the flame can be explained by high-temperature,weakly ionized,and species-abundant environment that are generated by the premixed CH_(4)/air flame.Effects of the gliding arc discharge on the premixed flames were demonstrated using planar laser-induced fluorescence of hydroxyl radicals(OH)and formaldehyde(CH_(2)O).OH and CH_(2)O can be formed in the CH_(4)/air mixture in the presence of the GA due to kinetic effects,and the increase of OH and CH_(2)O shows the great potential of the GA for combustion enhancement.

Mutual effects of nitric oxide and iron on the growth of marine algae

Experiments on the effects of nitric oxide （NO） and iron on the growth of marine microalgae Skeletonema costatum were conducted. The results are as follows： exogenous NO could increase the growth rate of marine algae and raise the biomass remarkably under iron-deficient conditions. But it was a complicated process that the phytoplankton growth was influenced by NO and iron, which was controlled by the NO concentration, the nutrition level of the culture medium and the iron concentration, etc. Meanwhile, the iron concentration in the medium also has a direct influence on the growth and NO release capacity of the algae. Therefore, the effects of NO and iron on the growth of marine phytoplankton were mutual.

Investigation of mutual effects among additives in electrolyte for plasma electrolytic oxidation on magnesium alloys

Plasma electrolytic oxidation(PEO)coatings were prepared on AZ91D magnesium alloys in alkaline silicate-based electrolyte with and without additives.The mutual effects among additives including TiC particles,dispersant polyethylene glycol 6000(PEG6000)and anionic surfactant sodium dodecyl sulfate(SDS)were studied based on orthogonal experiment.The content and distribution of TiC deposited in the coatings were measured by EPMA and EDS.The thicknesses,phase compositions,microstructures and corrosion resistances of the codlings were cAarnined by using TT260 eddy current tuickncss gage,XRD,SEM and clcctrochcniical test,respectively.The results show that the experiment design of this study is the key to study the mutual effects among these additives.Each additive and their interactions all remarkably influence TiC content and corrosion resistance of the coatings.Smaller size TiC is much easier to migrate towards the anode,and the interaction between PEG6000 and SDS both effectively prevents its agglomeration and increases the number of its negative surface charges,which further increase the migration rate and the deposited uniformity of TiC and make TiC have more opportunity to deposit in the discharge channel.Thus,when smaller size TiC,PEG6000 and SDS are all added into the electrolyte,they could improve the anti-corrosion property of the coating to the largest extent attributed to higher TiC content and the densest microstructure of the coating.

Accurate Fault Location Modeling for Parallel Transmission Lines Considering Mutual Effect

:A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system(TPTLS)as influenced by the mutual effect to determine the fault location is discussed in this work.The distance relay measures the impedance to the fault location which is the positive-sequence.The principle of summation the positive-,negative-,and zero-sequence voltages which equal zero is used to determine the fault location on the TPTLS.Also,the impedance of the transmission line to the fault location is determined.These algorithms are applied to single-line-to-ground(SLG)and double-line-to-ground(DLG)faults.To detect the fault location along the transmission line,its impedance as seen by the distance relay is determined to indicate if the fault is within the relay’s reach area.TPTLS under study are fed from one-and both-ends.A schematic diagrams are obtained for the impedance relays to determine the fault location with high accuracy.

Analytical modeling and approaches of multihelix cables incorporating with interwire mutual contacts

This study aims to develop an analytical model based on the curve beam theory to capture the mechanical response of a multihelix cable considering the internal contact displacements.Accordingly,a double-helix cable subjected to axial tension and torsion is analyzed,and both the line and point contacts between the neighboring wires and strands are considered via an equivalent homogenized approach.Then,the proposed theoretical model is extended to a hierarchical multihelix cable with mutual contact displacements by constructing a recursive relationship between the high-and low-level multihelix structures.The global tensile stiffness and torsional stiffness of the double-helix cable are successfully evaluated.The results are validated by a finite element(FE)model,and are found to be consistent with the findings of previous studies.It is shown that the contact deformations in multihelix cables significantly affect their equivalent mechanical stiffness,and the contact displacements are remarkably enhanced as the helix angles increase.This study provides insights into the interwire/interstrand mutual contact effects on global and local responses.

Neurotrophins and neural stem cells in posttraumatic brain injury repair

Traumatic brain injury(TBI)is the main cause of disability,mental health disorder,and even death,with its incidence and social costs rising steadily.Although different treatment strategies have been developed and tested to mitigate neurological decline,a definitive cure for these conditions remains elusive.Studies have revealed that vari-ous neurotrophins represented by the brain-derived neurotrophic factor are the key regulators of neuroinflammation,apoptosis,blood-brain barrier permeability,neurite regeneration,and memory function.These factors are instrumental in alleviating neu-roinflammation and promoting neuroregeneration.In addition,neural stem cells(NSC)contribute to nerve repair through inherent neuroprotective and immunomodulatory properties,the release of neurotrophins,the activation of endogenous NSCs,and in-tercellular signaling.Notably,innovative research proposals are emerging to combine BDNF and NSCs,enabling them to synergistically complement and promote each other in facilitating injury repair and improving neuron differentiation after TBI.In this review,we summarize the mechanism of neurotrophins in promoting neurogen-esis and restoring neural function after TBI,comprehensively explore the potential therapeutic effects of various neurotrophins in basic research on TBI,and investigate their interaction with NSCs.This endeavor aims to provide a valuable insight into the clinical treatment and transformation of neurotrophins in TBI,thereby promoting the progress of TBI therapeutics.

再生水投入与长江和黄河流域经济发展的互馈效应研究

基于面板向量自回归模型,收集了2011—2020年长江和黄河流域18个省(自治区、直辖市)的面板数据,在验证了面板数据的有效性基础上,分析了模型的结果、脉冲响应函数及方差分解结果,考察了再生水投入与长江和黄河流域经济发展之间的相互作用及动态双向影响。结果表明:再生水投入与长江和黄河流域经济发展之间具有相互促进、共同发展的关系,并具有区域差异性特征;在流域经济发展对再生水投入的影响上,黄河流域的依赖性明显大于长江流域;在再生水投入对流域经济发展的影响上,黄河流域和长江流域整体上均呈现正向影响,但长江流域正向影响滞后性更强。

国际中文教育促进中华文明传播力影响力提升策略研究

国际中文教育是增强中华文明传播力影响力的重要载体,增强中华文明传播力影响力为国际中文教育创新发展提供价值导向。文章首先诠释了国际中文教育和增强中华文明传播力影响力的内涵意蕴。其次,从逻辑关联和相互作用两个方面阐释二者之间的关系,逻辑关联表现为国际中文教育通过提升中文国际地位、促进文明交流互鉴、助力中外贸易畅通、促进中外民心相通等方式促进中华文明传播力影响力提升;相互作用表现为国际中文教育与增强中华文明传播力影响力互相影响,并在多元主体长期、稳定地支持下共同进步。最后,提出国际中文教育促进中华文明传播力影响力提升的路径:完善国际中文教育体系、提高国际中文教学质量、建强国际中文人才队伍、丰富国际中文产品服务以及强化现代科学技术赋能等。

深部软岩硐室群施工相互影响及变形破坏分析

地下矿山溜破系统服务年限长,其涉及卸载、破碎等多个大断面硐室。为解决硐室群施工过程中由于相互影响导致围岩变形破坏特征复杂的问题,以钟九铁矿-550~-590 m水平溜破系统硐室群为工程背景,基于弹塑性理论获取硐室围岩塑性区范围,并构建矿石和废石卸载硐室、下部溜井、破碎硐室和储矿仓8个大断面硐室数值模型,分析单硐室施工和硐室群顺序施工过程中的围岩应力和变形时空分布特征,开展硐室群施工相互影响研究,并据此提出了变形控制方案。结果表明:随着溜破系统硐室群的顺序施工,废石破碎硐室、卸载硐室、储矿仓帮部最大变形呈线性增大趋势,帮部塑性区呈先增加后基本不变的趋势;已建设完成的硐室群会使后续施工硐室区域岩体质量变差,相比于施工单硐室,顺序施工至废石卸载硐室和废石储矿仓,其帮部变形分别增加了21.7%和53.4%,塑性区范围分别增加了32%和92%。研究成果可为钟九铁矿后续硐室施工和支护设计提供指导,对于类似矿山硐室群施工相互影响研究也有一定的参考意义。

低频三阶超心形指向性声源设计

为提高圆周阵列主极大的指向性增益,提出基于圆周等间距六元密排阵的低频三阶超心形指向性声源,利用点源方法对其波束特性进行研究与分析,得到了指向性声源的优化方案。以具有弱互辐射效应的单边辐射弯张换能器作为圆周密排阵阵元,利用有限元方法分析了三阶超心形指向性声源的声辐射特性,相比单极子声源,其主极大方向指向性增益为8.0 dB,可达到提高增益的目的。研制了实验样机,经水池实验获得该声源的工作特性:谐振频率为0.92 kHz,对应发送电压响应级为139.0 dB,−3 dB波束宽度为56.0°,各旁瓣小于−15.0 dB。有限元计算与实测结果验证了优化方案的可行性,实现了低频三阶超心形指向性发射。

紧凑空间下大规模数字相控阵混合ADC接收机性能分析

针对紧凑空间互耦效应影响下的大规模数字相控阵混合ADC接收机性能评估问题,提出一种混合ADC接收机性能分析方法。首先,通过联合考虑三维信道模型、互耦效应模型和ADC量化噪声模型,对互耦效应影响下的传播信道进行建模;然后,采用线性最大比合并接收机,基于随机矩阵理论,推导给定天线阵列拓扑结构下系统可达速率的闭式表达式;最后,分别对均匀线性阵列、均匀平面阵列在不同混合ADC配置方案下的可达速率进行理论计算和数值仿真。计算与仿真结果均表明优化混合ADC配置方案可以有效提升系统可达速率,该结论可以为紧凑空间下高可达速率的混合ADC接收机设计提供理论支撑。

具有相互干扰和恐惧效应的捕食模型的稳定性

研究一类具有相互干扰和恐惧效应的Lotka-Volterra食饵-捕食模型,分析解的有界性和系统平衡点的存在性,并给出系统持续性的充分条件,通过Dulac判别法得出正平衡点是全局渐近稳定的,具有相互干扰和恐惧效应的食饵-捕食模型能长期共存并保持生态平衡。

美国联盟体系数字治理互操作性提升及其战略效应

近年来,美国及其盟友持续提升在数字技术上的互操作性,这一趋势伴随着数字治理工具的普及而愈发显现。数字技术互操作性提升不仅体现为数字工具共享、数字技术标准趋同和数字信息跨国流动,其更深远的影响在于,平台化建设打通了国家之间的治理边界,使得各国从合作推动“数字治理”转向共享“基于数字的治理”。治理互操作性的提升将对联盟的凝聚力形态产生变革性影响,可能改变传统上主要基于外部威胁和有效制度设计的凝聚力形态,凸显基于内部兼容的联盟凝聚力形态。本文将这一过程视作联盟的内向化进程,伴随着数字化以及大模型通用化发展,联盟成员国间的国内议题相互嵌入、治理工具多国共享、治理模式走向趋同,成员国间的互动模式从传统的跨国协调模式转变为算法弥散模式。本文认为美国推动与其盟友技术互操作性的下一阶段,是实现基于国内治理互嵌的治理互操作性,进而使得美国联盟体系成员国凝聚力走向内向化进程,表现为高科技产业链重塑、情报信息实时共享、国内议题框架同质化等趋势,并在联盟内跨国战略协调、楔子战略效用、美国联盟伙伴国扩展以及国际格局阵营化等方面产生相应的战略效应。

基于数据驱动的高精度阵列测向方法

针对现有测向系统多信号适应能力弱、测向精度低的问题,提出一种基于数据驱动的高精度阵列测向新方法。该方法提取单信号入射时的输入特征向量,基于卷积神经网络构建单信号测向网络框架。利用信号的独立性,将多信号测向问题转化为单信号测向问题,在单信号训练网络的基础上实现多信号来波方向估计。仿真实验与理论分析结果表明,该方法有效减少了输入特征维数和网络训练样本数目,在多信号同时入射及阵列互耦效应条件下均获得了高精度的到达方向(Direction of Arrival,DOA)估计的测向结果。

边界形变互耦混响室屏蔽效能测试系统性能评估

混混响室复杂强电磁环境下开展材料屏蔽效能测试是电磁防护领域的研究热点。研究边界形变互耦混响室屏蔽效能测试系统性能,开展了动态范围、电场分布特性和不确定度三个方面的试验验证,结果表明:在实际测试中,测试结果小于60 dB即为可信测试值;在1~10 GHz频段内,互耦混响室发射室的空间电场标准偏差小于3 dB,接收室的空间电场标准偏差小于2 dB,满足国际、国内相关标准要求,场均匀性良好;测试系统的扩展不确定度为5.90 dB,可以作为材料屏蔽效能测试平台使用。

文明交流互鉴视域下中华文化国际传播效力的提升

在文明交流互鉴视域下提升中华文化国际传播效力,一是要正确定位新时代中华文化国际传播的目标,向世界传播中国发展模式并说明其世界意义,全面、真实、立体地塑造国家形象和国民形象,促进文明交流互鉴、推动构建人类命运共同体;二是客观审视其在跨文化交流中语言结构与文化内倾问题以及“固定成见”造成的“误读”等现实障碍;三是在文明交流互鉴中对中华文化进行挖掘阐释,在民族特色与文化共通的交融中提升中华文化国际传播的实效性和影响力;四是在自尊自信、平等互利基础上,坚持“尊重”“平和”“包容”与“坚毅”的实践态度,推进中华文化国际传播走向新高度。

通风围阱内部导流措施分析与应用

为保证各路风管的排风机间不相互干扰,风量满足设计要求,提出一种用于通风围阱内部的导流措施。对通风围阱内部的导流结构进行介绍,并对其在实船的应用效果进行分析。结果表明:在通风围阱内部设置导流结构可有效增强通风效果。研究成果可为通风围阱内部导流措施设计提供一定参考。

互感式自调零正交涡流传感器设计与研究

针对涡流检测过程中传感器易发生提离和摇晃造成缺陷误判和漏检的问题,利用电磁场理论,研究了双Pancake式线圈之间的零互感特性,提出了一种互感式正交自动调零涡流传感器;同时搭建了基于六轴机器人引导的涡流检测系统,对铝筒体轴向和环向表面裂纹进行了相关实验研究。结果表明:相比同轴型涡流传感器,该传感器在筒体缺陷检测过程中对提离和摇晃的抑制力更佳,通过面内旋转其激励线圈至0°和90°,能够清晰地识别出铝筒体轴向和环向的表面裂纹。该传感器在不依赖高精度姿态校准前提下,有效解决了提离和摇晃造成缺陷误判和漏检的问题,对导电结构外场原位检测具有重要的应用意义。

粤港澳大湾区4种生态系统调节服务的互馈关系及机制

调节服务是生态系统为维持或改善人类生存环境提供的惠益。各种调节服务相互作用或存在互馈关系,并在不同时空尺度上呈现一定规律性或分异性,厘清不同尺度下生态系统调节服务间的关系及其影响因子对优化生态系统区域管理具有重要意义。以粤港澳大湾区为例,计算了2000、2010、2020年碳储量、氮输出量、土壤保持量和授粉者丰度等4种生态系统调节服务,在千米格网和二级流域尺度下分析生态系统服务时空格局变化,利用Spearman相关指数和地理回归模型分析了粤港澳大湾区生态系统服务间关系的时空异质性,最后通过最优地理探测器识别生态系统调节服务的主要影响因子及其交互作用力。结果表明:1)研究区生态系统调节服务的分布格局在时间上保持稳定,在空间上呈现异质性,但因调节服务的类型不同,其空间分布模式有所不同;2)研究区20年间生态系统调节服务间权衡/协同关系存在显著变化,且彼此存在不同程度的互馈关系,这些关系的作用强度随时空尺度的变化而变化。该研究确定了最佳互馈组合,包括碳储量-氮输出量、碳储量-土壤保持量、碳储量-授粉者丰度、氮输出量-土壤保持量和授粉者丰度-土壤保持量,这些组合中的后者服务因子对前者服务因子的解释力更强;3)生态系统中存在复杂的相互作用和非线性关系,这些关系对生态系统空间格局有显著影响,且调节服务因子与自然-社会经济影响因子的交互作用随着尺度的增大而增强。该研究可为区域差异化生态系统管理政策提供重要的科学参考。

共同机构投资者、会计信息可比性与非效率投资关系实证分析

选取2016—2021年沪深A股上市企业为样本,以会计信息可比性为中介变量,探讨共同机构投资者对企业非效率投资的作用机制。结果发现,共同机构投资者会降低企业非效率投资程度,会计信息可比性在二者之间发挥完全中介作用。进一步分析发现,共同机构投资者可以缓解企业过度投资与投资不足,会计信息可比性的中介效应在缓解企业投资不足方面更加显著;共同机构投资者的退出威胁促进会计信息可比性对企业非效率投资的抑制作用。文章结论为完善公司治理体系提供一定参考。