Simulation of liquid cone formation on the tip apex of indium field emission electric propulsion thrusters

Field emission electric propulsion(FEEP) thrusters possess excellent characteristics, such as high specific impulse, low power requirements, compact size and precise pointing capabilities,making them ideal propulsion devices for micro-nano satellites. However, the detection of certain aspects, such as the evolution process of the liquid cone and the physical quantities at the cone apex, proves challenging due to the minute size of the needle tip and the vacuum environment in which they operate. Consequently, this paper introduces a computational fluid dynamics(CFD) model to gain insight into the formation process of the liquid cone on the tip apex of indium FEEP. The CFD model is based on electrohydrodynamic(EHD) equations and the volume of fluid(VOF) method. The entire cone formation process can be divided into three stages, and the time-dependent characteristics of the physical quantities at the cone apex are investigated. The influences of film thickness, apex radius size and applied voltage are compared.The results indicate a gradual increase in the values of electrostatic stress and surface tension stress at the cone apex over an initial period, followed by a rapid escalation within a short duration.Apex configurations featuring a small radius, thick film and high voltage exhibit a propensity for liquid cone formation, and the cone growth time decreases as the film thickness increases.Moreover, some unstable behavior is observed during the cone formation process.

A novel seed cone of Pinus from the Miocene of coastal Southeast China indicates kinship with Southeast Asian pines

Pinus is an economically and ecologically important genus whose members are dominant components globally in low-latitude mountainous and mid-latitude temperate forests.Pinus species richness is currently concentrated in subtropical mid-low latitudes of the Northern Hemisphere,differing from the latitudinal diversity gradient mostly recognized in woody angiosperms.How the present pattern was developing in Earth's past is still poorly studied,particularly in eastern Asia.Here,a new fossil species,Pinus shengxianica sp.nov.is described based on a fossil seed cone from the Late Miocene Shengxian Formation in Zhejiang,southeast China.A co-occurring cone is recognized as a known fossil species,Pinus speciosa Li.Extensive comparison of extant and fossil members of Pinus suggests P.shengxianica shares a striking cone similarity to Pinus merkusii and Pinus latteri(subsection Pinus)from tropical Southeast Asia in having annular bulges around the umbo on the apophysis.The morphological resemblance indicates these two extant low-latitude pines probably possess a close affinity with the present newly-discovered P.shengxianica and originated from East Asian mid-low latitude ancestors during this generic re-diversification in the Miocene.This scenario is consistent with the evolutionary trajectory reflected by the pine fossil history and molecular data,marking the Miocene as a key period for the origin and evolution of most extant pines globally.The co-occurrences of diverse conifers and broadleaved angiosperms preferring diverse niches demonstrate Late Miocene eastern Zhejiang was one of the hot spots for coniferophyte diversity and hosted a needled-broadleaved mixed forest with complex vegetation structure and an altitudinal zonation.

Transcriptome Analysis of Auxin Drives Cone Size Regulation in Fokienia hodginsii

As the reproductive organ of the endangered species Fokienia hodginsii,the size of the cones is a constraint on the reproductive renewal of the population.In this study,the molecular basis of the influence of cone size on F.hodginsii was elucidated by comparing the phenotype,biochemistry,and transcriptome of two cultivars of F.hodginsii(‘FJ431’and‘FJ415’).The two cultivars differed significantly in cone size,with FJ431 having a significantly larger cone size and weight than FJ415,1.32 and 1.90 times that of FJ415,respectively.RNA-Seq analysis of both cultivars retrieved 75,940 genes whose approximate functions were classified as the pathway of response to endogenous stimulus and response to hormone and showed significant differences in the auxin-activated signaling pathway,particularly the MAPK signaling pathway-plant.Furthermore,the endogenous IAA content was significantly higher in FJ431 than in FJ415,and 1.58 and 1.29 times more IAA was present in immature and mature cones,respectively.Moreover,exogenous IAA treatment significantly induced the expression of the MAPK pathway-related gene TRINITY_DN10564_c0_g1 and significantly inhibited the expression of the MAPK pathwayrelated gene TRINITY_DN17056_c0_g1.Our work suggests that IAA can affect the cone size of F.hodginsii,most probably through the MAPK pathway.This has high theoretical and practical significance for the improvement of genetic breeding and the further cultivation of quality germplasm resources of F.hodginsii.

An Alternative Way to Mapping Cone: The Algebraic Topology of the Pinched Tensor

In this research, we explore the properties and applications of the mapping cone and its variant, the pinched mapping cone. The mapping cone is a construction that arises naturally in algebraic topology and is used to study the homotopy type of spaces. It has several key properties, including its homotopy equivalence to the cofiber of a continuous map, and its ability to compute homotopy groups using the long exact sequence associated with the cofiber. We also provide an overview of the properties and applications of the mapping cone and the pinched mapping cone in algebraic topology. This work highlights the importance of these constructions in the study of homotopy theory and the calculation of homotopy groups. The study also points to the potential for further research in this area which includes the study of higher homotopy groups and the applications of these constructions to other areas of mathematics.

Determination of undrained shear strength using piezocone penetration test in clayey soil for bridge foundation

In order to obtain the reasonable undrained shear strength Su for geotechnical analyses of bridge foundations in Yangtze River floodplain clayey soils, a site-specific study is conducted using the imported piezocone penetration test （CPTu） with dissipation phases at the Fourth Nanjing Yangtze River Bridge construction sites. Taking the values of Su from laboratory tests as references, several existing Su-predicted methods based on CPTu are compared and evaluated. To verify the presented cone factor Nk, additional test sites are selected and examined. The results show that the values of cone factors such as Nkt, Nke, and Nau, depend on the shear test mode and disturbance. Generally, the values of Nke show more scattering than those of Nkt and N△u. For the stratified and layered sediments of the Yangtze River floodplain, it is recommended using the net cone resistance qT to estimate Su and the preliminary cone factor values Nkt are from 7 to 16, with an average of 11. It is also confirmed that the CPTu test, as a new technique in site characterization, can present reasonable parameters for bridge foundations.

Technique for Estimating the Cone Bearing Smoothing Parameters

Cone penetration testing (CPT) is an extensively utilized and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic cone into penetrable soils and recording the resistance to the cone tip (qc value). The measured qc values (after correction for the pore water pressure) are utilized to estimate soil type and associated soil properties based predominantly on empirical correlations. The most common cone tips have associated areas of 10 cm2 and 15 cm2. Investigators also utilized significantly larger cone tips (33 cm2 and 40 cm2) so that gravelly soils can be penetrated. Small cone tips (2 cm2 and 5 cm2) are utilized for shallow soil investigations. The cone tip resistance measured at a particular depth is affected by the values above and below the depth of interest which results in a smoothing or blurring of the true bearing values. Extensive work has been carried out in mathematically modelling the smoothing function which results in the blurred cone bearing measurements. This paper outlines a technique which facilitates estimating the dominant parameters of the cone smoothing function from processing real cone bearing data sets. This cone calibration technique is referred to as the so-called CPSPE algorithm. The mathematical details of the CPSPE algorithm are outlined in this paper along with the results from a challenging test bed simulation.

CHARACTERIZATION OF SOLID CONES

The author gives a dual characterization of solid cones in locally convex spaces. From this the author obtains some criteria for judging convex cones to be solid in various kinds of locally convex spaces. Using a general expression of the interior of a solid cone, the author obtains a number of necessary and sufficient conditions for convex cones to be solid in the framework of Banach spaces. In particular, the author gives a dual relationship between solid cones and generalized sharp cones. The related known results are improved and extended.

Multicriterion Clustering Model with Cone Dominated Structure

A multicriterion clustering model with cone dominated structure is established and the concept of cone-efficient clustering is put forward. The properties of cone-efficient clustering are disscussed, and a method to solve multicriterion clustering is put forward.The model of Ref.[3] is a special case of that proposed in this paper.

用CONE法研究木材阻燃剂FRW的阻燃性能

利用锥形量热仪 (CONE)系统地测定了新型木材阻燃剂FRW的阻燃性能 ,讨论了FRW对阻燃木材在燃烧时的热释放、质量变化及耐点燃性的影响 ,并与Dricon阻燃剂进行了对比。结果表明 ,在 5 0kW·m2 的热辐射功率下 ,FRW阻燃处理木材的热释放速率 (RHR)和总热释放量 (THR)随FRW载药率的升高而降低 ,至载药率达到 10 %左右时 ,RHR及THR降低为未处理木材的 5 0 %左右 ,并且降低的趋势明显变缓 ;FRW与Dri con阻燃木材的有效燃烧热 (EHC)曲线基本重合 ,说明二者的阻燃机理类似 ;FRW阻燃木材的质量损失速率(MLR)曲线与RHR曲线相似 ,失重和热释放主要发生在有焰燃烧阶段 ;FRW阻燃处理能显著提高木材燃烧时的成炭率 ,但对木材的点燃时间影响不大 ;FRW与Dricon的阻燃效力相当 ,属高效木材阻燃剂。

用CONE法研究木材阻燃剂FRW的抑烟性能

采用锥形量热仪 (CONE)法系统地测定了新型木材阻燃剂FRW的抑烟性能 ,讨论了FRW对木材燃烧时发烟及烟气毒性的影响 ,并与Dricon阻燃剂进行了对比。结果表明 ,当热辐射功率为 5 0kW·m- 2 时 ,FRW阻燃处理木材的烟化率SR、比消光面积SEA、二氧化碳浓度CO2 及二氧化碳产率YCO2 比未处理木材显著降低 ;FRW阻燃处理对木材燃烧时一氧化碳的生成元显著影响 ;FRW与Dricon均具有很强的抑烟作用 。

聚合物材料燃烧性和阻燃性的评价—锥形量热仪(CONE)法

介绍了一种新一代的实验室型聚合物材料燃烧性能和阻燃性能的评价方法—锥形量热仪。锥形量热仪的实验结果更接近聚合物材料在实际燃烧时的行为。详细地讨论了各种燃烧参数在评价和研究聚合物材料的燃烧性和阻燃性中的意义和应用，并介绍了这方面的进展和发展方向。

阻燃PET的CONE/TGA研究

研究了由双 (对 -羧苯基 )苯基氧化膦改性的 PET共聚物的阻燃性质。测定了样品的极限氧指数 (L OI)。采用热重分析仪 (TGA)对试样的热降解行为进行了分析。通过锥型量热仪分析了共聚物及纯 PET样品的燃烧行为 ,显示共聚物具有较好的综合阻燃特性 ,如质量损失速率、热和烟的释放速率等 ,这些性质仅仅通过 L OI和 TGA分析是不能确定的。研究结果表明 ,通过 CONE/

基于CONE数据的材料热释放速率随辐射通量变化的研究

采用锥形量热仪测得几种材料在不同辐射通量下的燃烧性能数据,研究了不同的热辐射通量对热释放速率峰值、热释放速率平均值以及材料的点燃时间、到达峰值的时间、熄灭时间的影响。结果表明:同种材料在不同辐射通量下的热释放速率曲线形状是相似的,并且热释放总量是一个定值;平均热释放速率和热释放速率峰值是辐射通量的线性函数关系;点燃时间随着辐射通量的增加而呈指数衰减趋势;到达热释放速率峰值与火焰熄灭的时间基本上随着热辐射通量的增加线性递减。

Microstructures and formation mechanism of headstand pyrocarbon cones developed by electromagnetic-field-assisted CVD

Novel headstand pyrocarbon cones （HPCs） with hollow structure were developed on the surfaces of pyrocarbon layers of the carbon/carbon （C/C） composites at 650-750 °C by the electromagnetic-field-assisted chemical vapor deposition in the absence of catalysts. The fine microstructures of the HPCs were characterized by high-resolution transmission electron microscopy. The results show that the textural features of the HPCs directly transfer from turbostratic structure in roots to a well-ordered high texture in stems. And the degree of high texture ordering decreases gradually from the stem to the tail of the HPCs. The formation mechanism of the HPCs was inferred as the comprehensive effect of polarization induction on electromagnetic fields and particle-filler property under disruptive discharge.

用CONE法研究竹材的阻燃性能

以毛竹为对象,利用锥形量热仪,在5 0kW·m- 2 的热辐射功率下,对毛竹去除竹青保留竹黄(去青)、去除竹黄保留竹青(去黄)以及竹杆上、中、下(保留竹青竹黄)不同部位的竹材进行了燃烧性能的测定,分析了它们的燃烧性。结果表明,点燃时间、第二释热峰出现的时间及峰值、质量损失速率与竹材两表面的去与不去有极显著线性相关关系;竹杆部位与点燃时间有极显著性,与质量损失速率(峰值)有显著相关,与第二释热峰出现的时间及峰值分别为无显著相关及有一定相关;比消光面积与竹材两表面的去与不去及竹杆部位无显著相关。

新一代评估方法——锥形量热仪(CONE)法在材料阻燃研究中的应用

利用新一代评估方法———锥形量热仪法对材料阻燃机理、材料危险性等级划分、烟毒释放评价、材料燃烧性及阻燃性评价等方面的应用进行了分析讨论 ,结果表明锥形量热仪法对阻燃剂、阻燃制品的研究开发及阻燃剂在火灾中的行为研究具有重要意义。

用CONE研究阻燃PET的阻燃和烟释放

利用锥型量热仪 ( CONE)在 5 0 k W/ m2的热辐照条件下 ,研究了纯 PET和阻燃 PET的阻燃和烟释放。通过对获得的质量损失速率 ( MLR)、最大热释放速率 ( pk- H RR)、总热释放 ( TH R)、有效平均燃烧热 ( av- EH C)、平均烟比率 ( av- SR)、平均比消光面积 ( av- SEA)及 CO、CO2 释放量的分析表明 ,阻燃PET的 pk- H RR、TH R和 av- EH C等比纯 PET有明显的降低 。

Cone and Ovule Development in Platycladus orientalis (Cupressaceae)

Seed cone in Platycladus orientalis (L.) France consists of four or five pairs of decussate bracts. Usually, two pairs of the fertile bracts in the middle of the cone subtend six ovules, which initiate in an acropetal manner. Only one ovule presents on each of the upper fertile bract, while two ovules initiate from a common primordium in the axil of lower bracts. In Beijing, most female cones initiated in July. All parts of the cone formed before dormancy, which occurred during November to the next January. After pollination in March, bract morphology changed dramatically; intercalary growth of the bract base formed a conspicuous protuberance, in which inverted vascular system developed. Furthermore, ovules on different pairs of bracts initiated in an acropetal manner and two ovules in each lower fertile bract initiated from a common primordium, which was different from the basipetal initiation of ovules and independently formed single ovule as reported by Takaso in Calltris

Collapsed Cone光子束剂量计算方法研究

剂量计算是放射治疗计划系统的核心,与常用的笔形束剂量计算方法相比,collapsed cone卷积/叠加剂量计算方法具有更高的计算精度,为此我们研究了collapsed cone卷积/叠加剂量计算方法及加速算法,开发了一套基于collapsed cone卷积/叠加剂量计算方法的光子束放射治疗计划系统,并运用蒙特卡罗方法对剂量计算的准确性进行了验证。实验结果表明剂量计算误差与射束能量、射野尺寸以及剂量计算分辨率有关,当天顶角增量和方位角增量分别取3.75°和15°时,对于3～20 cm的方野,剂量计算误差均小于1.5%。所开发的collapsed cone光子束剂量计算方法准确可靠,可望应用于临床。

运用X-cone单孔器械行经脐单孔腹腔镜胆囊切除术

目的:探讨运用X-cone单孔器械完全经脐单孔腹腔镜胆囊切除术的方法和可行性。方法:回顾性分析我院2011年4月至2011年11月期间54例经脐单孔胆囊切除患者的临床资料。结果:本组54例均运用X-cone单孔腹腔镜器械经脐行单孔腹腔镜胆囊切除术,2例因胆囊炎症严重,解剖不清,改为二孔法腹腔镜手术,其他均手术成功,成功率96.3%。本组病例手术时间平均(30±14)(20～58)min,出血5～50mL,平均10.6mL。术后次日恢复流汁饮食,住院时间3～4d。随访至今,1例患者切口液化,无其他术中、术后并发症。术后患者无瘢痕效果十分满意。结论:运用X-cone单孔腹腔镜器械经脐单孔腹腔镜胆囊切除术具有同样的手术安全性,更具有突出的切口美容效果,术后疼痛轻、康复快、住院时间短,同时患者住院费用低,值得在临床广泛推广。