Investigation on the Natural Modes of A Semi-Closed Floating Tank

Vessels with semi-closed tanks(i.e.,well docks)are widely applied in the military operation and maritime engineer-ing.The water is bound by the semi-closed floating tank and forced by both the incident waves and ship’s motions.The free surface oscillations inside the flooded well dock is thus distinctive and very complicated.So far,the natural modes of semi-closed floating tanks have not yet been studied.This paper investigates the characteristics of natural modes of a floating semi-closed tank by combining a mode-resolving model based on mild-slope equations and a hydrodynamic model based on computational fluid dynamics.Results show that the first three natural periods(i.e.,74,23.6,and 14 s)of the tank fall into the band of swell and infragravity waves and they could be triggered under certain circumstance.Multi-period free surface oscillations are observed inside the tank,including the longest natural period(i.e.,74 s),though the incident waves are monochromatic.A possible generation mechanism for the long-period mode is explained on the basis of liquid sloshing and harbor oscillations.Moreover,a long-period component with a period close to the natural mode of well dock is observed in the ship motions,which is generated by the interaction between the waves and ship.

Semi-closed synthesis of nitrogen and oxygen Co-doped mesoporous carbon for selective aqueous oxidation

Heteroatom-doped meso/micro-porous carbon materials are conventionally produced by harsh carbonization under an inert atmosphere involving specific precursors,hard/soft templates,and heteroatom-containing agents.Herein,we report a facile synthesis of N and O co-doped meso/micro-porous carbon(NOMC)by template-free carbonization of a small-molecule precursor in a semi-closed system.The semi-closed carbonizaiton process yields hydrophilic NOMCs with large surface area in a high yield.The porous structure as well as the elemental composition of NOMCs can be modulated by changing the holding time at a particular temperature.NOMCs as metal-free heterogeneous catalysts can selectively oxidize benzyl alcohol and its derivatives into aldehydes/ketones with>85%conversion in aqueous solution,which is much higher than that of the control sample obtained in tube furnace(21%conversion),mainly due to their high N content,high percentage of pyridinic N,and large surface area.The presence of O-containing moieties also helps to improve the hydrophilicity and dispersion ability of catalysts and thus facilitates the mass transfer process during aqueous oxidation.The NOMC catalysts also dispayed excellent activity for a wide range of substrates with a selectivity of>99%.

Study on Deposition in Semi-Closed Coastal or Estuarine Harbour Basins

A preliminary study on the distribution of sediment transport and siltation within a semi-closed harbour as well as the factors affecting the siltation has been made with a suspended sediment model, in which the Lianyungang port is used as the prototype. Based on the work, this paper describes a tubid water experiment within a typical excavated harbour basin. According to the experimental results some expressions for predicting the average siltation amount for semi-closed harbour basins by means of dimensional analysis have been proposed, with tidal features, harbour geometry and properties of sediment taken into account. Through comparing the calculated results with the laboratory and field measured data, it has been shown that the expressions presented in this paper are reasonable.

How Did Vinh Moc Village, Located near Vietnam DMZ, Protect Their Villagers from United States Air Force Bombardment during the Vietnam War?

The buried village is Vinh Moc where more than 1200 Vietnamese, including soldiers, who lived underground during the Vietnam War (1965 to 1972) were hand dug into red basalt bedrock. The Vinh Moc Village was strategically located on the border of North Vietnam and South Vietnam approximately 14 km north of the DMZ and along the shoreline of the South China Sea. During the Vietnam War, the US Air Force heavily bombed Vinh Moc. The North Vietnamese Army (NVA) had an important military base on nearby Con Co Island. Brave civil volunteers from Vinh Moc would make the 28 km dangerous journey to the island, disguised as fishermen, to deliver supplies to the soldiers stationed there. The people who remained at Vinh Moc dug tunnels into red basalt hills in order to survive this onslaught. The American forces assessed the villagers of Vinh Moc were supplying food and armaments to the NVA garrison on the island of Con Co, which was in turn hindering the American bombers on their way to bomb Hanoi. The US military objective was to force the villagers of Vinh Moc to leave the area. The villagers initially dug the tunnels to a 10 m depth but the American forces designed bombs that burrowed down 10 m before exploding. The soil tunnels were then deepened to 30 m to provide safety for the soldiers and civilians working there during the intense US Air Force bombing. The primary objective of the research study was to determine how the soils and parent material of Vinh Moc Village, protected their villagers from the United States Air Force bombardment during the Vietnam War. In addition, the natural parent material at both the Vinh Moc and Cu Chi were assessed to determine why the tunnels were so resilient. The Cu Chi and Iron Triangle soil tunnels were dug by hand in the Old Alluvium soils and parent material where iron in solution precipitated and became the soil binding material. The Vinh Moc tunnels were hand dug in porous, red basalt (bedrock) hills where the consolidated rock structure itself provided the required binding material. Neither site needed support beams to hold up the ceilings.

Comprehensive bioinformatic analysis of mind bomb 1 gene in stomach adenocarcinoma

BACKGROUND The carcinogenesis of stomach adenocarcinoma(STAD)involves many different molecules and multiple pathways,including the NOTCH signaling pathway.As a key factor that functions as a critical link in the NOTCH pathway,mind bomb 1(MIB1)is upregulated in various tumors and has been reported to promote cell metastasis and invasion.However,studies on the role of MIB1 in STAD are limited.Here,we evaluated the prognostic value of MIB1 in STAD and its association with immune infiltration and copy number variation.AIM To elucidate the relationship between MIB1 gene and gastric cancer(GC)and provide a new idea for the treatment of GC.METHODS We identified mutations in the MIB1 gene by searching the cBioPortal database and then analyzed their relationship with the overall survival rate and diseasefree survival rate using the Kaplan-Meier method.The Cancer Genome Atlas(TCGA)database provided transcript levels for MIB1 in STADs and normal tissues.As a method of distinguishing the STAD tissues from adjacent normal tissues,a receiver operating characteristic(ROC)curve was generated.Kaplan-Meier plotter was used to determine the effect of MIB1 expression on survival.Based on the LinkedOmics database,we were able to identify the coexpressed genes of the MIB1 gene,the top 50 positively correlated genes,and the top 50 negatively correlated genes.STRING was used to construct protein-protein interaction networks related to the MIB1 gene.An analysis of functional enrichment was carried out using the R package“Cluster Profiler”.The relationships between mRNA expression of MIB1 and immune infiltrates were assessed by Tumor IMmune Estimation Resource(TIMER)and the“GSVA package”in R.RESULTS According to the cBioPortal database,the MIB1 mutation rate in 287 patients in the TCGA dataset was approximately 6%.Kaplan-Meier survival analysis showed that patients with STAD in the mutated group had a worse prognosis than those in the unmutated group(P=0.0156).There was a significant upregulation of MIB1 expression in STAD tissues compared to adjacent normal tissues.A high T stage was associated with increased MIB1 mRNA expression.The ROC curve analysis revealed 59.4%sensitivity and 85.6%specificity of MIB1 for differentiating STAD tissues from adjacent normal tissues at a truncation level of 2.248.Kaplan-Meier plotter indicated that patients with higher MIB1 levels had a worse prognosis than those with lower levels(26.4 mo vs 56.2 mo,P=0.0330).A correlation analysis demonstrated an association between immune infiltrates and MIB1 mRNA expression.CONCLUSION Upregulation of MIB1 expression is significantly associated with poor survival rate and immune infiltration in gastric adenocarcinoma.MIB1 may be a biomarker for the poor prognosis of STAD patients and a potential immunotherapeutic target.

基于正交试验的民用飞机抗爆结构参数敏感性分析

最小风险炸弹位置(LRBL)结构是放置飞机上可疑爆炸物的装置,探究结构尺寸和炸药位置对其抗爆性能的影响程度可为其改进设计提供参考。基于正交试验设计与数值模拟相结合的方法,以LRBL结构各危险部位的最大应变和变形为评价指标,分别运用极差分析法和方差分析法对LRBL结构的罐体壁厚、底盖厚度、连接凸台厚度、剪切销直径和炸药位置5个影响因素开展参数敏感性分析。结果表明:在200 g炸药当量的工况下,各因素对LRBL结构的抗爆性能的影响显著程度从大到小为炸药位置、罐体壁厚、底盖厚度、凸台厚度和剪切销直径;结合评价指标综合分析得到各个因素最优水平下的LRBL结构设计方案。

饲用油脂总能测定条件优化研究

试验选用氧弹量热法进行饲用油脂总能测定条件优化研究。选用豆油、调和油作为试验材料,研究是否添加基质对总能测定结果的影响,进行检测方法优化;选用11种油脂作为试验材料,验证不同试样质量(0.4、0.6、0.8、1.0、1.2 g)对测定结果的影响;选用5种油脂作为试验材料,比对不同仪器对测定结果的影响。结果表明:测定豆油总能,添加基质后测定结果变异系数大,重复性差(P<0.05),不添加基质重复性好(P>0.05);不添加基质方法进行日内、日间试验,测定结果差异不显著(P>0.05),测定结果稳定性好(P<0.05)。不同试样质量对豆油、调和油、椰子油、月桂酸、鱼油、鸡油1#、鸡油2#、猪油1#、猪油2#等9种油脂总能测定结果差异不显著(P>0.05),对棕榈油总能测定结果表现为差异显著(P<0.05),对磷脂总能测定结果表现为差异极显著(P<0.001),试样质量适宜范围为0.6~0.8 g。两种氧弹量热仪测定椰子油、棕榈油、豆油、月桂酸、磷脂5种油脂相同试样质量,测定总能结果差异不显著(P>0.05)。本试验条件下,油脂测定试验无需添加基质,该方法测定总能结果稳定、重复性好。不同试样质量对豆油、调和油、椰子油、月桂酸、鱼油、鸡油1#、鸡油2#、猪油1#、猪油2#等9种油脂表现为差异不显著,适宜试样质量为0.4~1.0 g;对棕榈油表现为差异显著,适宜试样质量为0.6~1.0 g;对磷脂表现为差异极显著,适宜试样质量为0.8~1.0 g。用两种氧弹量热仪测定油脂总能结果无明显差异。

苏联氢弹研制科学理论基础的奠定——核聚变理论工作(1946—1953)

1946—1953年间,苏联4个科研团队的核聚变理论工作,既是苏联氢弹研制的首要工作,也是苏联核计划的重要组成部分,为氢弹研制奠定了科学理论基础。库尔恰托夫团队负责分析情报信息并向政府提供建议,对其他小组的工作进行管理并开展了少许的理论研究工作;泽利多维奇小组是苏联最早对轻核聚变可行性进行研究的团队,开展了与“管式构型”氢弹相关的核聚变理论工作;朗道小组从工作伊始就探索核聚变理论的实际应用问题,就两种构型的氢弹开展了重要的理论计算工作;塔姆小组提出并完善了“层式构型”氢弹的设计构想,并开展了与此相关的核聚变理论工作,在苏联首枚氢弹的研制中发挥了关键作用。他们开展的核聚变理论工作为苏联氢弹研制的设计理论、技术理论等理论问题提供了科学依据,在热核装药的选择、引爆问题、爆炸过程、能量释放以及试爆工作等实际问题的解决中起到了极其重要的理论指导作用。核聚变理论工作不仅为苏联氢弹研制的成功提供了理论保障,而且在某种程度上还加深了核裂变理论的相关研究,进而构建并强化了苏联核武体系的科学理论基础,而且还进一步改进了对原子弹、氢弹的研发工作,大大增强了苏联的国防力量。

内生的主体性视角下“两弹一星”精神的弘扬及实践路径探索

自我国科研人员获得“两弹一星”辉煌成就以来,凝聚了那一代人浓郁家国情怀的“两弹一星”精神也应运而生。“两弹一星”精神体现了中国人民在困难时期自力更生、艰苦奋斗、勇往直前的精神风貌。迄今为止,“两弹一星”精神仍然具有突出的时代意义。它不仅是中国科技发展的宝贵财富,更是激励中国人民不断前行、实现中华民族伟大复兴的精神力量。在新时代,我们每一个人要响应党的号召、听从祖国召唤,继续传承弘扬“两弹一星”精神,让其焕发出更加璀璨的光芒。弘扬“两弹一星”精神不仅有助于传承优良传统、激励创新发展,还能增强国家凝聚力、塑造民族精神。文章结合马克思的主体性思想,探讨内生的主体性与“两弹一星”精神之间的关系,从本体论、认识论、价值论和方法论四重维度着手,基于个体对“两弹一星”精神的认知、情感、意志三个心理过程,探索新时代弘扬“两弹一星”精神的实践路径,推进个体自觉弘扬“两弹一星”精神,进而增强国家和民族凝聚力,实现人类社会的共同繁荣与进步。

李政道的首次美国之行及国籍变迁

1957年,旅美青年才俊李政道和杨振宁一起荣幸地成为最早获得诺贝尔奖的中国人。1946年,李政道受民国政府研制原子弹“种子计划”的派遣赴美研习,1950年获得博士学位,1956年取得美国永久居留权(绿卡),1963年入籍美国。李政道科艺双馨,长期致力于推动科学和艺术的融合,他身在海外,心系祖国,呕心沥血,亲力亲为,竭尽全力地为中国的人才培养以及基础科学的进步与发展出谋划策,贡献卓著。本文介绍了李政道简略生平,借助于家族网(www.familysearch.org)重点梳理了他首次美国之行及国籍变迁的相关情况,澄清了一些常见错讹。

“两弹一星”精神在青海中小学育人教育中的实践路径探索

推进爱国主义教育是落实立德树人根本任务的内在要求与应有之义。“两弹一星”精神是爱国主义教育的重要内容之一,青海省是“两弹一星”伟大精神的发源地,具备丰富的教育资源。而青少年阶段是形成世界观、人生观、价值观的重要时期,因此,因地制宜地提出“两弹一星”精神在青海中小学育人教育中的实践路径,具有重要的育人价值和激励作用,对培养新时代社会主义建设者和接班人具有重要意义。基于大中小学思政课一体化的整体视域,从学生成长发展规律出发,以不同学段对象的特点和教育目标为依据,在中小学思政教育中加强“两弹一星”精神教育。通过加强中小学生对“两弹一星”人物故事和精神的基本认知,升华中小学生的爱国主义、集体主义情感,促进中小学生形成高尚的三观,提高“两弹一星”精神教育的目的性和有效性,充分发挥本土伟大精神对中小学生的育人价值和功能。

张爱萍将军研究述评

张爱萍将军在抗日战争时期领导军民创建了皖东北、苏北抗日根据地。中华人民共和国成立后,他是第一支人民海军——华东海军的创建者,我军第一次陆海空三军联合作战的指挥者,“两弹一星”伟大事业的领军人。另外,他还是著名的将军诗人、书法家、摄影家。回顾和总结学者对张爱萍将军研究的有关成果,有助于进一步推动这一课题走向深入。

航空炸弹气动特性及弹道特性仿真研究

为了研究气动布局对航空炸弹弹道特性的影响,设计了不同气动外形的航弹模型;利用ANSYS FLUENT对航弹模型在亚音速、跨音速、超音速时飞行流场进行了数值仿真,并获得了主要气动特性参数;建立了基于水平投弹的直角坐标系下的航弹质心运动数学模型,利用已经获取的气动力参数进行航弹模型的弹道特性分析、弹道轨迹仿真计算。结果表明,气动布局的合理优化可以有效降低航弹飞行阻力进而改善其弹道特性,可提供落点行程变化范围800.4~3 212.8 m;通过弹道系数、标准下落时间、极限速度可以表征航弹弹道特性,但航弹飞行轨迹受到多因素共同影响,其中,在投弹速度与航弹行程之间存在着最佳匹配区间。研究结果可以为航空炸弹气动布局优化设计及其工程应用提供理论基础与技术支撑。

横流环境中灭雷弹弹道特性分析与优化

针对高横流环境中灭雷具定深投弹的精准度难以达成,通过灭雷弹物理参数和海流环境构建灭雷弹数值计算模型,采用有限元法对投弹过程进行仿真,分析了初速和横流条件对灭雷弹弹道的影响。进一步以灭雷弹重心位置和尾部直径为设计参数,以弹着点位置误差为目标函数,结合粒子群算法对高横流条件下的灭雷弹运动进行联合仿真优化。结果表明:由于海水阻力较大,灭雷弹初速对弹道影响很小,横流的流速对弹道的影响较大;优化后的灭雷弹在下落时保持倾斜姿态,弹着点位置偏差降低约94%;建立的多目标优化模型为精准投弹设计提供依据。

乙醇-氢气-空气混合燃气的层流燃烧速度测定

为了研究乙醇的层流燃烧特性,在定容燃烧弹内,分别研究了初始压力为0.3 MPa,氢气比例为50%时,不同初始温度(370 K和450 K)和当量比(0.7~1.4)下,氢气-乙醇混合燃气的火焰传播规律。计算得到了混合燃气的层流燃烧速度和马克斯坦长度,分析了拉伸率对火焰传播速度的影响,同时将研究结果与文献数据进行了比较,验证了计算模型的可靠性。结果表明:随着初始温度的增加,混合燃气的层流燃烧速度也会随之提升;当量比的增加也会提升混合燃气的层流燃烧速度,在当量比为1.2时达到了峰值,随后开始降低。初始温度的增加会在一定条件下会导致火焰的不稳定;在初始温度370 K下,马克斯坦长度始终大于0,火焰一直处于稳定状态;初始温度450 K、0.7~0.9当量比下的马克斯坦长度小于0,火焰出现了不稳定状态,因为较高的初始温度会产生强烈的对流和湍流效应,这些效应会使火焰的边界层受到扰动,造成火焰不稳定;不同初始温度下的马克斯坦长度都随当量比的增加而增加,火焰的稳定性不断提升。对计算得到的层流燃烧速度进行数据拟合,得到了计算乙醇-氢气-空气混合气层流燃烧速度的关系式。

拓展高原环境的航空炸弹弹道快速解算方法

为快速、精确地求解高原环境下的航空炸弹弹道,在经典弹道模型的基础上,面向高原环境提出一种基于改进Runge-Kutta的航空无控炸弹弹道解算(improved Runge-Kutta based uncontrolled bombs trajectory calculation,IRK-UBTC)方法。首先,针对炸弹下落过程中时刻变化的环境参数,提出了基于起飞点的空气比重函数估算方法。然后,引入战斗机所处环境的温度、湿度、纬度、科尔奥利力等信息对经典炸弹质心运动微分方程组进行重构。最后,在三阶Runge-Kutta算法的基础上,提出了带误差控制机制的微分方程组实时解算方法。实验结果表明,该方法在1.4 GHz主频的嵌入式计算机中的解算周期小于5 ms,且最大射程误差小于0.2%,能够被有效应用于高原地区航弹弹道的实时解算。

引信天线罩形变遥测图像动态测试方法

针对传统形变测试方法不适用于在高速、高温、高过载的恶劣环境中进行引信天线罩形变动态测试的问题,提出一种基于遥测的非接触式引信天线罩形变动态测试方法。该方法将CMOS图像传感器安装在天线罩内部,对飞行过程中引信天线罩内表面进行在线拍摄,将拍摄到的图像利用无线遥测传输到地面,通过地面图像分析和特征解算获得引信天线罩的变形量曲线。其中变形量计算的关键技术采用了Hough圆检测方法,具有精度高、抗干扰能力强等优点。实验结果表明,该方法满足天线罩动态测试需求,能够测量出天线罩飞行过程中产生的形变量。

爆炸位置对钛合金定向泄爆容器冲击响应的影响

研究了不同位置炸药爆炸作用下钛合金定向泄爆容器的冲击响应。通过试验与数值模拟,分析了100 g TNT炸药放置不同位置时容器的抗爆性能和冲击端头的飞行角度,并以限制罐体运动为目的,对罐体轴向受力进行了分析。研究表明:爆炸物位于轴线时,罐体产生弹性形变;紧贴内壁中间位置时,罐体外壁鼓包并贯穿开裂;紧贴内壁近端头处时,罐体外壁凸起。100 g TNT炸药作用下,冲击端头出口速度均值为124.45 m/s、最大偏角为2.3°,且爆炸物位置对端头出口速度影响较小。爆炸物位于轴线前、后端时,轴向力较爆炸物位于轴线中心时分别增大173%和116%。该研究可为民机定向泄爆容器及连接结构设计提供参考。

容弹内片状无烟煤粉喷射掺混特性实验研究

粉末在容弹以及发动机燃烧室内的掺混状态对粉末爆轰特性有较大的影响,因此亟须对粉末在有限空间内的喷射掺混特性展开研究。搭建了一套透明的容弹系统,通过高速摄影监测系统,对片状煤粉在容弹内的喷射掺混过程进行观测,并对高速摄影拍摄图片进行后处理,分析煤粉在容弹内的喷射掺混变化规律。针对煤粉喷射掺混图像建立了一种灰度值标准差曲率分析方法,研究发现标准差曲率趋于0的初始时刻为煤粉掺混均匀最佳时刻,可以选取为最佳点火时间点,且该方法所选取的时刻与逐帧分析高速摄影图像所选取的时刻吻合。在煤粉浓度为120 g/m^(3),210 g/m^(3),300 g/m^(3)下,依次展开煤粉喷射掺混实验,并应用此灰度图像标准差曲率分析方法进行分析。实验结果表明:保持煤粉浓度一致时,掺混均匀性最佳时间随喷粉时长的增长而逐渐缩短,点火时刻提前;保持喷粉时长一致时,掺混均匀性最佳时间随供粉浓度的增长而延长,点火时刻延后。

大空间尺度下预燃室射流火焰发展历程的光学诊断和模拟研究

基于定容燃烧弹,在与大型低速预燃室式双燃料船机相似的空间和热力学条件下,采用相似的点火过程,对主燃烧室内的射流火焰发展和引燃预混火焰的扩展历程进行光学测试;提出一种基于全网格映射,分阶段采用不同的燃烧模型的方法模拟不同燃烧阶段的火焰发展过程。基于定容装置试验数据验证了模型对燃烧火焰扩展速度预测的适用性和准确性。研究结果表明:预燃室燃油喷射量直接影响射流火焰的最大贯穿距离和火焰强度;主燃烧室内的混合气需要达到一定浓度才能被引燃。对燃烧过程的模拟,第一阶段燃烧采用均质搅拌反应器(well-stirred reactor,WSR)模型可以较为准确地模拟不同燃油喷射量下的射流发展速度和火焰射流的最大贯穿距离;第二阶段燃烧采用G方程可以较为准确地模拟火焰在各方向上的扩展速度。采用Mapping方法连接的两个模型对燃烧两个阶段的火焰扩展的整体速度具有较高的预测精度。