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火箭弹尾翼外形选型研究
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作者 李真 吴晶 +3 位作者 张志倩 曾凡桥 王小兵 芮亮 《兵器装备工程学报》 CAS CSCD 北大核心 2022年第S02期35-39,共5页
分析了尾翼形式对火箭弹气动特性的影响,通过保证最小静稳定度相同的方式匹配了对比模型,采用数值模拟的方法计算得到两种外形的气动参数。根据计算结果分析了两种尾翼形式火箭弹的气动特性,详细讲解了静稳定度、阻力系数、升力系数、... 分析了尾翼形式对火箭弹气动特性的影响,通过保证最小静稳定度相同的方式匹配了对比模型,采用数值模拟的方法计算得到两种外形的气动参数。根据计算结果分析了两种尾翼形式火箭弹的气动特性,详细讲解了静稳定度、阻力系数、升力系数、升阻比、自诱导滚转力矩及面外力矩等参数的变化规律,研究了滚转角对气动特性的影响。文末根据气动特性分析结果结合工程经验,提出一些外形设计建议,供火箭弹总体设计参考。 展开更多
关键词 火箭弹 卷弧尾翼、直尾翼、气动特性外形设计
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厄尔尼诺发生期冬春季西北印度洋鸢乌贼耳石外形生长特性 被引量:17
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作者 陆化杰 王洪浩 +3 位作者 刘凯 陈炫妤 何静茹 陈新军 《生态学杂志》 CAS CSCD 北大核心 2020年第11期3694-3703,共10页
耳石是头足类重要的硬组织器官之一,是研究头足类年龄与生长、种群结构和生活史等重要材料。根据2019年厄尔尼诺发生期冬春季(2—5月)我国灯光罩网渔船在西北印度洋海域调查生产期间采集的1009尾鸢乌贼(Sthenoteuthis oualaniensis)样本... 耳石是头足类重要的硬组织器官之一,是研究头足类年龄与生长、种群结构和生活史等重要材料。根据2019年厄尔尼诺发生期冬春季(2—5月)我国灯光罩网渔船在西北印度洋海域调查生产期间采集的1009尾鸢乌贼(Sthenoteuthis oualaniensis)样本,对厄尔尼诺发生期耳石的外形生长特性进行了研究。结果表明,西北印度洋海域鸢乌贼耳石具有宽大的翼区,较小的背区与吻区。主成分分析表明,耳石总长(TSL)、翼区长(WL)、侧区长(LDL)和最大宽度(MW)可以作为研究鸢乌贼耳石外形生长的特征参数。协方差分析表明,耳石的各特征参数与胴长(ML)、体质量(BW)间的生长关系均存在性别间显著性差异。赤池信息准则(AIC)表明,雄性TSL、WL与ML的生长最适用对数函数表示,LDL、MW与ML的生长最适用线性函数表示,雌性TSL、WL、LDL和MW与ML的生长最适用对数函数表示;雄性TSL、WL与BW的生长最适用对数函数表示,LDL、MW与BW的生长最适用幂函数表示,而雌性TSL、WL、LDL、MW与BW的生长均最适用对数函数表示。随着鸢乌贼个体的增大,其耳石各参数的绝对尺寸逐渐变大,但相对尺寸逐渐减小。本研究结果为后续利用耳石研究鸢乌贼种群鉴定、生活史提供了科学依据,也为研究极端天气变化对头足类硬组织生长的影响提供了参考。 展开更多
关键词 鸢乌贼 耳石外形特性 生长 西北印度洋海域 厄尔尼诺
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大蒜播种机在新疆种植区的改进适应性研究及试验
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作者 石鑫 牛长河 +2 位作者 王学农 杨会民 刘旋峰 《农机化研究》 北大核心 2023年第4期101-106,共6页
为解决新疆大蒜种植机械化程度低的问题,对比了分析新疆吉木萨尔白皮、伊犁紫皮大蒜和山东金乡蒜的外形差异,对引进的山东玛丽亚生产的2BU-7型大蒜直立播种机进行改进优化,同时设计铺滴灌带覆膜机构为提高大蒜播种机在新疆干旱种植区的... 为解决新疆大蒜种植机械化程度低的问题,对比了分析新疆吉木萨尔白皮、伊犁紫皮大蒜和山东金乡蒜的外形差异,对引进的山东玛丽亚生产的2BU-7型大蒜直立播种机进行改进优化,同时设计铺滴灌带覆膜机构为提高大蒜播种机在新疆干旱种植区的适应性提供依据。通过基础数据研究优化了关键部件,对改进后的大蒜播种机进行试验,结果显示:当改进后的大蒜铺滴灌带、覆膜播种机前进速度为2km/h时,大蒜正芽率达到91.4%,重播率为4.5%,空穴率为3.2%,损伤率为4.9%,各项性能指标最优,且滴灌带纵向拉伸率为0.6%,满足《滴灌铺管铺膜精密播种机质量技术评价技术规范》要求。 展开更多
关键词 大蒜 播种机 外形特性 新疆种植区
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Buckling analysis of the shell of a refuge chamber in a coal mine under uniform axial compression 被引量:4
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作者 Fang Haifeng Ge Shirong +1 位作者 Cai Lihua Hu Eryi 《International Journal of Mining Science and Technology》 2012年第1期85-88,共4页
A stiffened cylindrical shell is normally used in refuge chambers of a coal mine. Based on the method of application and shape characteristics of a refuge chamber, we simplified its shell as an orthotropic cylinder. T... A stiffened cylindrical shell is normally used in refuge chambers of a coal mine. Based on the method of application and shape characteristics of a refuge chamber, we simplified its shell as an orthotropic cylinder. The basic buckling equation of the stiffened cylindrical shell under uniform axial compression was deduced by using a Donnell function. The factors affecting its buckling capacity were studied by theoretical analysis and numerical calculations. The results reveal that the torsional rigidity of the longitudinal stiffener had little effect on the buckling capacity of the shell and that the critical load of an externally stiffened cylindrical shell is higher than that of an internally stiffened cylindrical shell. 展开更多
关键词 Refuge chamber BUCKLING Axial compression Stiffened cylindrical shell
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THE STATISTIC ANALYSIS OF SCREEN PARAMETERS ON PERFORMANCE CHARACTERISTICS
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作者 王汝林 A.C.Apling 《Journal of Coal Science & Engineering(China)》 1997年第1期74-78,共5页
A series of laboratory screening tests have been performed with the objective of evalu-ating the effect of feed rate, screen length and screen motion on the quality of separation achieved. The statistic analysis and r... A series of laboratory screening tests have been performed with the objective of evalu-ating the effect of feed rate, screen length and screen motion on the quality of separation achieved. The statistic analysis and results derived from it are discussed. Suggestions for future work with the objective of assessing the industrial significance of the research to the optimisation and design of screening processes are presented. 展开更多
关键词 analysis of variance optimum condition separation efficiency
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Two Organic Phase Suspension Polymerization for Novel Hypercrosslinked Resin Bead by Polycondensation of CMB
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作者 赵林秀 张鑫 +2 位作者 吕邢鑫 原思国 武现丽 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第4期447-452,共6页
The suspension polymerization with two organic phases was adopted to prepare spherical hyper- crosslinked resin by self-polycondensation of 4,4'-bis-(chloromethyl)- 1, 1'-biphenyl (CMB). The chemical structure,m... The suspension polymerization with two organic phases was adopted to prepare spherical hyper- crosslinked resin by self-polycondensation of 4,4'-bis-(chloromethyl)- 1, 1'-biphenyl (CMB). The chemical structure,morphology and pore characteristics of the novel spherical resin were characterized with Fourier transform infrared spectroscopy (FTIR), micrograph and Brunauer-Emmett-Teller (BET). It is found that the suspension system and stirring speed impose a great influence upon the regularity and size distribution of hypercrosslinked beads. To prepare CMB resin beads with diameter of about 300 μm, the optimal condition is as follows: stirring speed 300 r·min^-1, and the volume ratio of the two organic phases (nitrobenzene/dimethyl silicon oil) 1 : 5. After the self-polycondensation and sqccedent post-crosslinking of CMB monomer, the spherical adsorbent presents high spec^al surface area (1190 m^2· g^-1) and abundant pore^volume (0.714 cm^3· g^-1), and could be potentially applied qn the adsorption of various organic molecules and synthesis of porous ion exchanger. 展开更多
关键词 two organic phase suspension polymerization hypercrosslinked resin bis chloromethyl monomer
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Mixed P3HT/PCBM Organic Thin-Film Transistors: Relation between Morphology and Electrical Characteristics
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作者 Khairul Anuar Mohamad Afishah Alias +3 位作者 Ismail Saad Bablu Kumar Gosh Katsuhiro Uesugi Hisashi Fukuda 《Journal of Chemistry and Chemical Engineering》 2014年第5期476-481,共6页
The mixed P3HT (poly(3-hexylthiophene)) and [6,6]-PCBM (phenyl C61-butyric acid methyl ester) organic thin films were investigated for electronic structure using UV-Vis spectrophotometer and PESA (photo-electro... The mixed P3HT (poly(3-hexylthiophene)) and [6,6]-PCBM (phenyl C61-butyric acid methyl ester) organic thin films were investigated for electronic structure using UV-Vis spectrophotometer and PESA (photo-electron spectroscopy in air). Furthermore, ESR (electron spin resonance) and AFM (atomic force microscopy) were used to investigate the surface morphology and molecular orientation, respectively. ESR analysis indicated the molecular orientation of the P3HT crystalline in the blend thin films, which the crystalline oriented normal to the substrate with distribution of 35°. AFM images indicated that the surface morphology of P3HT film was affected by the presence of PCBM nanoparticles. Solution-processed OTFTs (organic thin-film transistors) based on P3HT/PCBM blend thin film in a top source-drain contact structure was fabricated, and the electrical characteristics of the devices were also investigated. A unipolar property with p-channel characteristics were obtained in glove box measurement. 展开更多
关键词 Organic semiconductor P3HT PCBM P3HT/PCBM blend thin film organic thin-film transistor.
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