Dynamic modeling of cavitation bubble clusters:Effects of evaporation,condensation,and bubble-bubble interaction

We present a dynamic model of cavitation bubbles in a cluster,in which the effects of evaporation,condensation,and bubble-bubble interactions are taken into consideration.Under different ultrasound conditions,we examine how the dynamics of cavitation bubbles are affected by several factors,such as the locations of the bubbles,the ambient radius,and the number of bubbles.Herein the variations of bubble radius,energy,temperature,pressure,and the quantity of vapor molecules are analyzed.Our findings reveal that bubble-bubble interactions can restrict the expansion of bubbles,reduce the exchange of energy among vapor molecules,and diminish the maximum internal temperature and pressure when bursting.The ambient radius of bubbles can influence the intensities of their oscillations,with clusters comprised of smaller bubbles creating optimal conditions for generating high-temperature and high-pressure regions.Moreover,an increase in the number of bubbles can further inhibit cavitation activities.The frequency,pressure and waveform of the driving wave can also exert a significant influence on cavitation activities,with rectangular waves enhancing and triangular waves weakening the cavitation of bubbles in the cluster.These results provide a theoretical basis for understanding the dynamics of cavitation bubbles in a bubble cluster,and the factors that affect their behaviors.

Effect of annealing time on the exchange coupling interactions and microstruc-ture of nanocomposite Pr_(7.5)Dy_1Fe_(71)Co_(15)Nb_1B_(4.5) ribbons

The influence of annealing time on the magnetic properties and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons was systematically investigated by the methods of vibrating sample magnetometer （VSM）, X-ray diffraction （XRD） and high resolution transmission electron microscopy （HRTEM）. Interaction domains derived from strong exchange coupling interactions between hard and soft magnetic grains were imaged using magnetic force microscopy （MFM）. Maximum remanence, intrinsic coercivity, and maximum energy product values were obtained in the ribbons annealed at 700℃ for 15 min, which were composed of Pr2（Fe, Co）14B, α-（Fe, Co）, and slight Pr2（Fe, CO）17 phases. Although Jr, Hci, and （Bn）max decreased gradually with further increase of annealing time, it is emphasized that comparatively high Jr and Hci and （BH）max were obtained in a wide annealing time period of 15 to 360 min. The shape of initial magnetization curves and hysteresis loops change as a function of annealing time, indicating different magnetization reversal routes, which can be fully explained by the corresponding microstructure.

Exchange interactions and magnetic properties of intermetallic compounds

The temperature dependence of lattice parameters a and c of intermetallic compounds RMn 2Ge 2(R=La, Sm and Gd)were measured in the temperature range of 10800 K by using the X-ray diffractometer . It is found that the high temperature magnetic transitions of Mn-subsystem in light rare earth compounds from paramagnetic to antiferromagnetic state accompany the negative magnetoelastic anomalies of lattice parameters c, where a does not change. This indicates that the antiferromagnetic component of intralayer Mn-Mn exchange coupling is correlated with lattice constant c. The low temperature first order ferromagnetism→antiferromagnetism transitions(or antiferromagnetism→ferromagnetism transition) of Mn-subsystem in SmMn 2Ge 2 and GdMn 2Ge 2 accompany the abruptly decrease(or increase) of lattice parameter a, and Δa/a≈0.15%. This demonstrates that the interlayer Mn-Mn exchange interaction is very sensitive to the intralayer Mn-Mn distance. The critical value of lattice constant a k, at which the interlayer Mn-Mn coupling changes its sign, is 4.044 5×10 -10 m. Based on the molecular field model of exchange interaction the magnetic curves of GdMn 2Ge 2 single crystal at different temperatures were calculated and a good agreement with experimental data had gotten. The Gd-Gd, Gd-Mn, intralayer Mn-Mn and interlayer Mn-Mn exchange coupling parameters were estimated.

Exchange Interactions and Ferromagnetism of Pr_(n+1)Co_(3n+5)B_(2n)-type Compounds

In present investigation exchange interactions of Pr_(n+1)Co_(3n+5)B_(2n)-type compounds have been evalu- ated in the light of molecular-field theory. The exchange interactions and ferromagnetism in these compounds are discussed in terms of lattice parameters and interatomic distance between Co atom.

Effect of Thickness on Magnetic Dipolar and Exchange Interactions in SmCo/FeCo/SmCo Thin Films

SmCo/FeCo/SmCo trilayer was deposited with two different thickness configurations for soft phase (FeCo);50 nm/10 nm/50 nm and 50 nm/25 nm/50 nm were deposited on Si (111) substrate and Ta (50 nm) seed layer by RF magnetron sputtering in a pressure, p, of 30 - 35 m Torr. After deposition the films were annealed under Ar atmosphere at temperature T equal to 923 and 973 for different times followed by quenching in water. X-ray diffraction patterns were obtained to identified phase presents and calculate average crystallite size. To study the effect of configuration thickness in soft phases, DC magnetic measurements were carried out;the measurements were done in the temperature interval of 300 - 50 K. Hysteresis loops collected at low temperatures exposed an increment in coercivity with the decrease of T and at same time, presented a “knee” in the second quadrant of the demagnetization curve, which suggests that the inter-layer exchange coupling becomes less effective, being more evident for sample with 50 nm/25 nm/50 nm thickness. Moreover, δM (H) plots were calculated from magnetic measurements at three different temperatures, T, equal to 300, 150 and 50 K, which corroborates that the dipolar interactions became stronger when thickness of soft phases increases. Finally, the thickness effect is attributed to the SmCo5 phase magnetocrystalline anisotropy constant, which is responsible for the exchange coupling length.

Dataset of Comparative Observations for Land Surface Processes over the Semi-Arid Alpine Grassland against Alpine Lakes in the Source Region of the Yellow River

Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot. However, the characteristics of the lake-atmosphere interaction over the high-altitude lakes are still unclear, which inhibits model development and the accurate simulation of lake climate effects. The source region of the Yellow River(SRYR) has the largest outflow lake and freshwater lake on the TP and is one of the most densely distributed lakes on the TP. Since 2011,three observation sites have been set up in the Ngoring Lake basin in the SRYR to monitor the lake-atmosphere interaction and the differences among water-heat exchanges over the land and lake surfaces. This study presents an eight-year(2012–19), half-hourly, observation-based dataset related to lake–atmosphere interactions composed of three sites. The three sites represent the lake surface, the lakeside, and the land. The observations contain the basic meteorological elements,surface radiation, eddy covariance system, soil temperature, and moisture(for land). Information related to the sites and instruments, the continuity and completeness of data, and the differences among the observational results at different sites are described in this study. These data have been used in the previous study to reveal a few energy and water exchange characteristics of TP lakes and to validate and improve the lake and land surface model. The dataset is available at National Cryosphere Desert Data Center and Science Data Bank.

从竞生走向共生:六堡茶传承中的多民族交往交流交融与互嵌式发展——铸牢中华民族共同体意识的广西实践系列之四

茶文化是中华优秀传统文化的重要组成部分,是各民族交往交流交融的载体和结晶。六堡茶是岭南地区的特色茶,体现了瑶族与汉族饮食文化的共生之美。在六堡茶文化的变迁过程中,通过“舜帝南巡”“茶箩娘”等民间叙事,岭南先民对中华文化的认同得到延承;通过制茶技艺从瑶族内部家族传承到各民族间师徒传承方式的转变,区域社会中的族际关系从竞生最终走向共生。同时,当前六堡茶从“侨销茶”向“畅销茶”的发展转向有助于多民族互嵌式的产业共同体建设。在铸牢中华民族共同体意识的时代背景下,六堡茶已成为一种富有情感共鸣和精神认同的文化符号。

青藏高原东南缘不同类型生态系统碳、水交换特征

青藏高原东南缘横断山脉地区是南亚和东亚季风的交汇处,也是大气变化的敏感区和热源区。开展该地区地气相互作用对区域水热过程影响机制及其参数化研究,对于研究青藏高原大气水汽传输的关键过程问题有重大意义。本文介绍了基于涡动观测法开展的青藏高原东南缘地区的地气相互作用观测试验,并总结了洱海湖面、丽江高山草甸及腾冲北海湿地的地气交换特征,以及利用数值模式开展复杂山地局地环流特征的研究工作。目前已初步明确和揭示青藏高原东南缘横断山脉不同类型下垫面的地气交换特征及其影响因素,主要结论如下:青藏高原东南缘高山草甸的碳、水交换过程受降水分布影响显著,“浮毯型”湿地(水面常年覆盖有“浮毯”状苔草草排)的碳、水交换除了受气象因素影响外,也受到下垫面植被和水体比例变化的影响。不同类型生态系统的碳、水交换过程在不同时间尺度的影响因子存在差别。风速始终是湖泊潜热和CO_(2)交换的关键影响因子,而降水在较长时间尺度对湖泊CO_(2)通量也有显著影响。此外,青藏高原东南缘的复杂地形对于生态系统的碳、水交换过程也有显著影响。复杂地形产生的不同类型的局地环流对于生态系统的碳、水交换过程有不同的影响。

文化符号的传播与共享——以夏鲁寺、贡嘎曲德寺日月图像为例

西藏地区的夏鲁寺与贡嘎曲德寺壁画中均出现了以金乌、玉兔代表日与月的图像。金乌与玉兔图像是中原文化用来表示日与月的固定图式。自汉朝时期由西王母神话与民间信仰不断糅合产生,唐代时被吸收进佛教图像体系中,后期随着藏传佛教的兴盛与文化交流的频繁,藏传佛教绘画吸收了这种日月图像母题。西藏壁画艺术中的日月图像,不仅更新了藏传佛教艺术的表达范式,而且图像意义也突破了单纯宗教艺术的阐释,凸显了中央皇权的在场。夏鲁寺与贡嘎曲德寺壁画中的日月图像是汉藏文化交往交流交融的结果,彰显了元明时期各民族之间的频繁互动,以及多元文化交流下文化符号互融互生的整体性社会结构。

历史记忆、仪式实践与民族交往交流交融——滇西地区邓子龙信仰研究

历史记忆与仪式实践是联结区域社会共同体的重要载体。明朝中后期,中缅边境地区的各民族共同参与了抵抗缅甸入侵的战争,而奉命出征的邓子龙及其“平定边乱,保卫边民”的靖边史也成为滇西各民族代代相传的历史记忆。当地傣族、布朗族和汉族分别将邓子龙传说嫁接到各自的文化图式中,集体围绕邓子龙信仰举行“拜大关”“祭神刀”等仪式活动。从历时性的视角看,明代以来形成的邓子龙信仰为滇西地区铸牢中华民族共同体意识奠定了坚实的文化基础,成为构筑中华民族共有精神家园的精神纽带;从共时性的视角看,滇西地区各族人民通过邓子龙信仰以及共建文化景观、共祀靖边英雄、共享庙会节庆,促进了边疆地区各民族的交往交流交融,铸牢了边疆各民族的中华民族共同体意识。

人类文化互动的趋势——基于“文化工具论”的评析

在全球化时代,人类文化即各族群文化的互动演化趋势会怎样?马汉和亨廷顿认为这是“文化的冲突”,并先后给出了自己的系统论证。但他们说的文化冲突其实既不是文化本身的相互冲突,也不是由于文化的不同引发的冲突,而都是利益之争的冲突。除此外是否还会有可以成立的文化冲突论?根据“文化工具论”的评析也不会。因为文化的冲突只会出现在使用文化工具时仅有的两个特殊情境中,不可能成为具有普遍性的趋势。相反,文化的融合才是人类文化互动的趋势。因为文化是满足人需求的工具,工具的种类越多越好,于是,很多具有优越性和独特性的文化工具会从一个族群流入其他族群。也许有人担忧人类文化互动的融合趋势会消除族群文化的个性或世界文化的多样性,从而使人类文化不能继续在差异中相互促进。通过文化工具论的评析可知,这同样是完全不必要的担忧。

民族地区职业教育国际交流与合作的现实困境与优化策略

民族地区职业教育国际交流与合作在“一带一路”建设服务中发挥着重要作用。它是促进沿线国家民心相通的“友谊桥梁”,推进民族地区跨越发展的“强劲引擎”,也是助力民族职教“走出去”的“便捷通道”。在新形势下,民族地区职业教育国际交流与合作面临理念认知不足、资金投入不够、专业师资紧缺、合作质量不高、内涵建设不足等五大现实困境。针对此,需要从更新职教理念,推进国际化交流合作步伐;加大投入力度,规范职业教育国际化管理;加强团队建设,提高师资队伍国际化水平;提升合作质量,促进国际化办学纵深发展;强化内涵建设,打造民族职教国际化品牌等五个方面来找到民族地区职业教育国际化办学的有效路径。

满学研究视角下北京各民族交往交流交融史

北京各民族交往交流交融史是中华民族交往交流交融史研究的重要组成部分。目前学界有关北京史的学术史回顾和理论探讨,集中在文化史、城市史、区域史、社会史的范畴。与之相比,北京各民族交往交流交融的历史则较少被纳入学术史讨论的范畴。在传统区域史研究视角下,其主要以通论性研究为主,涉及北京民族融合的历史、民族文化、民俗、饮食、医学等方面。满学作为专门之学,探讨了清代八旗制度与北京、满语文与北京话、北京地区多语种文献、清代京师文化与当代京味文化等问题,为相关研究提供了新的视角。新时代的满学研究应更好地关注首都,关注北京各民族交往交流交融的历史,从首都的历史文化遗产中挖掘丰富的多民族融合因素。北京市社会科学院满学论坛(2023)聚焦“推动满学研究高质量发展繁荣发展首都哲学社会科学”主题,展现了满学领域对北京各民族交往交流交融史的最新研究成果。

民族走廊学说与区域舞蹈文化研究——以南岭民族走廊为例

本文以费孝通先生提出的民族走廊学说为研究视角,以南岭民族走廊为研究对象,对走廊所包含的东段粤北地区、中段桂东北地区、北段湘西南地区的瑶族、汉族、壮族、苗族、侗族、客家等族群舞蹈的分布及互动展开比较研究。拟从区域舞蹈文化研究的范式转变、民族迁徙、信仰流播、“中心”与“边缘”等多元视角来看族群舞蹈文化的互动互融,印证南岭民族走廊各族群在历史上的动态流变,以此阐释中华民族多元一体理论的形成与发展,为南岭民族走廊舞蹈文化研究提供更多研究的视角与案例。

明清鸡足山兴起中的多民族共塑与交融

大理宾川鸡足山是一座跨民族、跨地域、跨宗教的圣山。鸡足山在明清时期作为圣山兴起的过程,是区域社会中各民族对鸡足山景观的共同塑造、朝山盛节共庆、生产生活物资互通的过程,同时也是鸡足山被各民族接纳认可并被构建为多民族共享的文化符号的过程。一部鸡足山圣地的兴起史,于区域社会而言就是一段多民族共塑圣山的交往交流交融史。在各民族交往交流交融的实践过程中,鸡足山逐渐成为各民族共筑共享的精神家园。

节日表达与文化共生:节日促进散杂居地区民族乡村民族交往交流交融研究

散杂居地区民族乡村在经济发展上互为补充、文化上相互吸纳、生活上互相尊重,其节日文化中烙刻着中华民族共有的文化基因,成为散杂居地区民族乡村各民族交往交流交融的载体和媒介。就节日符号而言,可划分为中华民族共有传统节日、少数民族特色传统节日和新型节日。就节日促进散杂居地区民族乡村交往交流交融的媒介价值与实践逻辑而言,在日常生活实践、社会互动和文化认同中表明节日可以促进散杂居地区民族乡村各民族交往交流交融,并以节日为媒介构建出经济空间、互动空间和仪式空间来展现其实践逻辑,维系了地方认同和民族内聚力,促进了民族交往交流交融。重视挖掘节日的共有共享媒介价值,促进散杂居地区民族乡村各民族群众的广泛交往、全面交流、深度交融。

全国民族运动会铸牢中华民族共同体意识的价值内涵与实践路径

全国民族运动会的成功举办是党和国家立足国情,汲取历史滋养,将民族传统体育与民族工作相结合的具体实践。全国民族运动会已成为各民族交往交流交融历史事实的有效载体,成为促进民族团结、增强中华文化认同、传承中华优秀传统文化的重要平台。进入新时代,全国民族运动会在培养社会主义核心价值观、构建民族传统体育传承体系、坚持“以人民为中心”、融入全民健身、推进乡村文明建设等诸多方面发挥着积极作用,为铸牢中华民族共同体意识提供实践路径。

民族交往交流交融深化背景下节日文化空间的现代转向研究——以瞿昙寺“花儿”会为例

在上百年的历史传承中,瞿昙寺“花儿”会随着时代和社会的发展不断进行着自我调适,以应对外界的变化。近年来,在民族交往交流交融逐渐深入发展的背景下,瞿昙寺“花儿”会的变迁发展迅速又剧烈,活动形式与内容不断丰富与创新,其所承载的传统社会功能也随之改变。与此同时,其对周边地区各民族的交往交流交融也产生了较大的影响。由多民族共同参与的文化空间,既具有民族融合、多元共存的文化特征,又是各族人民历史文化长期积淀、交融的呈现。

交互共存:从甘青“花儿”看多民族的交往交流交融

“花儿”是生长在西北大地上的一朵艺术奇葩,蕴含丰厚的历史积淀和文化内涵。“花儿”是西北地区多民族集体的智慧结晶,也是多民族交往交流交融的文化自信和文化认同的基质。在中华文化的大熔炉中,“花儿”是其中的瑰宝,它的旋律流淌过岁月的文化长河,歌词浸染着各民族文化的鲜明色彩,以摄魂夺魄的艺术魅力,涤荡着千千万万民众的心灵,真正彰显了各民族交融共生的社会理路。文章以传唱在甘青地区最为广泛的河州“花儿”为例,以交互共存的文化特质为切入点,探讨甘青“花儿”中呈现的多民族交往交流交融,以期为铸牢中华民族共同体意识提供养分,为实现中华民族伟大复兴凝聚精神力量。

非交互密钥协商综述

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