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Search Results: 1 - 10 of 107625 matches for " 徐学哲 "
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正放四角锥网架敏感性分析及抗连续倒塌性能
Sensitive Analysis and Anti-Progressive Collapse Performance of Square Pyramid Space Grids

韩庆华,,
- , 2017, DOI: 10.11784/tdxbz201601079
Abstract: 为揭示正放四角锥网架的连续倒塌破坏机理, 采用备用荷载路径法并结合基于构件承载能力的敏感性评价指标, 对正放四角锥平板网架进行动力非线性分析, 模拟了结构的连续倒塌破坏过程, 分析了厚跨比、跨度和支承形式对网架结构抗连续倒塌性能的影响.分析结果表明, 周边点支承正放四角锥网架结构中部下弦杆、中间支座处腹杆为敏感构件, 结构中部上弦杆、中间支座周围腹杆和上弦杆为关键构件; 周边支承网架冗余度指标分布规律与周边点支承网架相似, 冗余度指标小于周边点支承网架; 点支承网架角支座腹杆和上弦杆为敏感构件, 敏感构件相邻腹杆及中间支座腹杆为关键构件.通过加强关键构件的截面尺寸, 可以显著提高结构的抗连续倒塌性能.正放四角锥网架冗余度指标分布规律不随厚跨比、跨度的变化而改变, 冗余度指标大小与网架厚跨比、设计应力比成正比, 而与模型跨度关系不大.
In order to reveal the progressive collapse mechanism of square pyramid space girds,a dynamic nonlinear analysis using alternate path method and sensitive indices based on bearing capacity of members was conducted. The progressive collapse process of structure was simulated,and the influence of span-thickness ratio,structural span and supporting form on the progressive collapse performance was analyzed. The results indicate that the sensitive components of square pyramid space grids with perimeter-point supports are the bottom chords in the center and the web members at intermediate supports,while the key components are the upper chords in the center and the upper chords and web members at intermediate supports. The distribution regularities of redundancy indices in grids with perimeter supports are similar to those of grids with perimeter-point supports,and the redundancy indices are much smaller. The sensitive components of grids with point supports are the upper chords and web members at corner supports,while the web members adjacent to the sensitive components and at the intermediate supports are the key members. By reinforcing the sectional dimensions of key components,the anti-progressive collapse performance of the structure can be significantly enhanced. The distribution regularities of redundancy indices do not change with the span-thickness ratio or structural span,and the value is proportional to span-thickness ratio and designed stress ratio but less related to structural span
基于数据的城市污水泵站系统建模
,,左燕,赵晓东,薛安克
化工学报 , 2010,
Abstract: 根据Gelormino管网LTI离散模型,结合实际推导出可行的广义数据模型,提出了系统辨识方法:(1)通过数据挖掘技术实现模型结构聚类;(2)采用相关性分析技术确定模型结构;(3)采用最小二乘法及渐消记忆递推最小二乘法实现模型参数辨识及在线辨识。实例计算结果表明,该方法建立的数据模型可以很好地模拟并预测泵站的污水流入量、污水总量以及水位变化情况,可用于指导城市污水泵站的运行管理。
城市道路车辆排放测试与模拟
王云鹏,, 李世武, 隗海林,
中国公路学报 , 2006,
Abstract: ?以长春市部分主干道为试验研究路段,采用一种车载排放测量仪器在实际道路上进行了单车排放试验,运用多项式回归的方法,整合车辆运行状况和排放数据,建立了单车实际道路微观排放模型。利用合作开发的基于路径的微观交通仿真系统与单车微观排放模型的有机结合,开发了一种可预测不同交通状况下交通干道排放的有效系统,并进行了仿真计算。结果表明:该系统不但可估算并预测车辆在某一路段的污染物排放水平,还可评价交通管理改进措施对车辆排放的影响。
绿茶对糖尿病大鼠抗氧化活性影响
,全吉淑,俊萍,许惠仙,及川和志
中国公共卫生 , 2007, DOI: 10.11847/zgggws2007-23-12-49
Abstract: ?绿茶富含茶多酚和茶多糖,具有很好的保健作用,如降脂〔1〕、抗诱变〔2〕、抗防止血栓形成和抗心肌缺血〔3〕等。近年来作为一种畅销茶饮料走入人们的生活。但其作用机制目前仍不十分清楚。Ⅱ型糖尿病患者常见的并发症是动脉粥样硬化,其代谢特点是血糖升高、血脂紊乱、脂质过氧化产物增多〔4,5〕。本文研究绿茶提取物对Ⅱ型糖尿病大鼠肝脏及血清过氧化脂质(LPO)水平、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性以及低密度脂蛋白(LDL)的影响,旨在为糖尿病及其并发症的膳食治疗提供依据。
两次碱一次回流法合成水溶性酚醛树脂胶粘剂
周太炎,杜郢,,,振宇
涂料工业 , 2012,
Abstract: ?采用两次碱一次回流法合成工艺代替一次法和两次碱法制备酚醛树脂胶黏剂,通过对酚醛比、反应时间、反应温度、回流时间等反应条件的考察得出:以n(苯酚)∶n(甲醛)=1∶2的比例,在70℃下反应40min,80℃下反应20min后升温回流反应45min得到具有交联结构的酚醛树脂胶黏剂,产品相对分子质量及黏度适中,拉伸剪切强度可达到5mpa以上,游离甲醛含量低于0.03%,稳定性较好。
寒地水稻节水增产高效正交设计试验研究 Study on water- saving high yield and high efficiency of rice in cold region by orthogonal design
,张忠,林彦宇,聂堂
- , 2015,
Abstract: 针对黑土区稻田高产栽培模式控制因素单一的现状,文章采用田间小区试验方法,利用正交设计原理,研究不同灌溉方式、各生育时期不同施肥比例、不同栽培密度等因素对同一品种水稻水分利用效率、有效穗数及产量影响的变化规律,从而实现寒地水稻水肥一体化高产高效管理技术模式。结果表明,三因素对产量、水分利用效率影响大小顺序:水分管理>施肥方式>栽培密度,对有效穗数影响大小顺序:栽培密度>水分管理>施肥方式;水分管理因素间差异对水稻产量及水分利用效率影响达显著水平,栽培密度因素间差异对有效穗数影响达极显著水平,水分管理因素间差异对有效穗数为显著水平;经因素不同水平综合分析比较,采用控制灌溉Ⅱ、施肥方式为基肥:蘖肥:穗肥:保花肥=4.5:2:1.5:2、栽培密度24穴·m-2管理技术模式,可以实现水稻节水、高产、高效一体化。
青藏高原北部植物叶片碳同位素组成的空间特征
陈拓,杨梅,冯虎元,世健,强维亚,何元庆,安黎
冰川冻土 , 2003,
Abstract: 测定了青藏高原北部13个地点101份草本植物叶片碳同位素组成(δ13C值),结果发现,植物叶片δ13C值的分布范围在-29.2‰~-23.8‰之间,平均值约为-26.89‰,明显低于全球高海拔植物叶片δ13C值(-2.6‰);而植物叶片δ13C值随海拔和经、纬度的变化趋势与其它同类报道相似随着海拔的升高和经、纬度的降低,植物叶片δ13C值呈现升高趋势.叶片δ13C值也随土壤含水量和土壤温度的变化而变化土壤含水量越高,土壤温度越低,植物叶片δ13C值越小,但它们之间的相关关系不具统计学意义.初步分析表明,大气压力(CO2分压)和温度的协同变化导致了叶片δ13C值随着海拔变化的分布格局,而温度和相对湿度的变化是引起叶片δ13C值的经、纬度效应的主要因子.
基于16SrRNA基因序列分析梅花鹿瘤胃细菌多样性
李志鹏,刘晗璐,,荆祎,鲍坤,,杨福合,李光玉
动物营养学报 , 2013, DOI: 10.3969/j.issn.1006-267x.2013.09.017
Abstract: 本试验旨在对以柞树叶为主要粗饲料来源的梅花鹿瘤胃细菌多样性进行分析。提取瘤胃微生物基因组DNA,扩增细菌16SrRNA基因,构建16SrRNA基因克隆文库,分析梅花鹿瘤胃细菌区系组成。结果表明:1)试验共得到107个非嵌合体16SrRNA基因序列。按照97%序列相似性,划分为22个分类操作单元(OTUs)。其中91个序列(10个OTUs,85%总克隆序列)与已培养菌序列相似性≥97%,13个序列(10个OTUs,12.2%总克隆序列)与已培养菌序列相似性为90%~97%,其余序列相似性<90%。87.9%序列与普雷沃氏菌属(Prevotellaspp.)相似。2)系统发育分析表明,梅花鹿瘤胃细菌由厚壁菌门和拟杆菌门组成。由结果可知,以富含单宁的柞树叶为主要粗饲料来源的梅花鹿的瘤胃中,普雷沃氏菌属是优势细菌,而牛、羊瘤胃中常见的纤维素降解菌未检测到,这可能与饲料中单宁含量高有关。
小麦抗叶锈病中间材料的 Lr24、 Lr38分子标记辅助选择
,,,,,,张立荣,张英姿,杨文香,刘大群
- , 2017, DOI: 10.7606/j.issn.1009-1041.2017.01.03
Abstract: 为加速小麦抗叶锈优质品种的培育,利用 Lr24、 Lr38的分子标记对优质品种豫麦34、中优9507和高抗叶锈品系1R17的杂交F3:4代的优质材料进行了目的基因的鉴定。结果从150份杂交后代F3:4中筛选出了70份聚合 Lr24和 Lr38的高抗优质材料,其余80份材料表型为抗叶锈病,但不含 Lr24和 Lr38或仅含二者之一。本研究避免了小麦抗叶锈病育种的盲目性,提高了抗叶锈基因选择的准确度。
冬小麦灌浆期旗叶对光密度与春化方式的光合响应
肖海,刘海俊,柳伟,舒国平,,刘晓英,志刚
南京农业大学学报 , 2017, DOI: 10.7685/jnau.201702014
Abstract: [目的]本文旨在探讨人工可控环境中满足灌浆期冬小麦生长发育的适宜光密度。[方法]以小麦品种‘扬麦16’为试验材料,自然光照+自然春化为对照(CK),设置人工光照(650 μmol?m-2?s-1)+自然春化(T1)、人工光照(500 μmol?m-2?s-1)+自然春化(T2)、人工光照(650 μmol?m-2?s-1)+种芽春化(T3)、人工光照(500 μmol?m-2?s-1)+种芽春化(T4)4个组合处理,研究了冬小麦灌浆期旗叶对光密度与春化方式的光合响应。[结果]T1、T2、T3和T4处理的千粒质量、旗叶Pn相对增率(VPn)和蒸腾速率均大于CK;T3、T4的光合潜能(Pmax)高于T1、T2和CK;T1的光饱和点高于T2,T3高于T4;T2的光补偿点和暗呼吸速率均低于T1,T4低于T3;T1的气孔导度高于T2,T3高于T4;T3、T4的旗叶气孔导度高于T1和T2。CK及T1、T2、T3、T4处理的千粒质量分别为33.58、47.67、44.42、49.66、46.31 g。[结论]500~650 μmol?m-2?s-1是人工可控环境中灌浆期‘扬麦16’生长发育的适宜光密度参数。
[Objectives]The aim of this study is to study the reasonable light intensity for winter wheat in the filling stage in artificial controllable environment.[Methods]The wheat variety ‘Yangmai 16’ was used as the experimental material. We set up four treatments:artificial light(650 μmol?m-2?s-1)+natural vernalization(T1),artificial light(500 μmol?m-2?s-1)+natural vernalization(T2),artificial light(650 μmol?m-2?s-1)+seed vernalization(T3),artificial light(500 μmol?m-2?s-1)+seed vernalization(T4),and natural light+natural vernalization was used as control(CK). The photosynthetic responses of flag leaf in the filling stage of winter wheat to light intensity and vernalization way were investigated.[Results]The results showed that the 1 000-grain weight,relative increase of flag leaf Pn(VPn)and transpiration rate of four treatments were greater than those of CK treatment. The maximum net photosynthetic rate(Pmax)of T3 and T4 were greater than that of T1,T2 and CK. The light saturation point(LSP)of T1 treatment was greater than T2,and T3 was greater than T4. The light compensation point(LCP)and dark respiration rate(Rd)of T2 were lower than T1,and T4 were lower than T3. The stomatal conductance(Gs)of T1 treatment was greater than T2,and T3 was greater than T4. The Gs of flag leaf of T3 and T4 were greater than T1 and T2.[Conclusions]The light intensity of 500-650 μmol?m-2?s-1 was the reasonable light intensity parameter for the growth and development of ‘Yangmai 16’ in the filling stage in artificial controllable environment
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