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Search Results: 1 - 10 of 72786 matches for " 贾永楠 "
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多机器人编队控制研究进展 Research development of multi-robot formation control
,李擎
- , 2018,
Abstract: 首先介绍了传统的编队控制方法的定义、特点和常用方法及优缺点,并将传统编队控制时代定义为前编队控制时代.随着多智能体技术的发展,将多智能体技术引入到编队控制问题中,诞生了众多新的研究成果,称为后编队控制时代.后编队控制时代以多智能体技术为基础,随着通信技术、计算机技术、人工智能技术的发展而逐渐壮大起来,并受到了学者的广泛关注.前编队控制时代强调多机器人通过编队协作完成单个机器人无法实现的任务,提高任务完成效率且缩短任务完成时间.后编队控制时代则是在前编队控制时代的基础上,更强调低成本、同步性和协同性,但却不那么重视每个个体的任务分工,甚至是按照规则自由分配任务,不再有"不可替代"的个体存在.最后给出了研究编队控制问题的基本思路和目前尚待解决的关键问题.
云计算环境下基于代表点增量层次密度聚类的微博事件检测及跟踪
,,东风
计算机应用 , 2013,
Abstract: ?为从微博服务平台产生的大量实时信息中抽取新闻事件,提出了一套完整的云计算环境下的微博事件检测跟踪算法。首先采用新的基于微博转发数和评论数的权值计算方法,将微博文本表示成向量空间模型;再利用基于代表点的增量层次密度聚类(rihdbscan)算法抽取关键词,最终实现新闻事件的检测和跟踪。针对单一节点无法快速高效地处理海量微博数据的问题,将算法部署在云计算平台hadoop上。通过在新浪微博平台上获取的真实数据进行实验,结果表明,所提出的权值计算方法比
海上风电复合筒型基础粉质黏土下沉试验分析
Analysis of Penetration Test of Composite Bucket Foundations for Offshore Wind Turbines in Silty Clay

丁红岩,,张浦阳,
- , 2017, DOI: 10.11784/tdxbz201610015
Abstract: 复合筒型基础的沉放是一项关键施工过程.沉放时土体在施工负压下受到扰动, 土体中土压力和孔隙水压力发生变化, 对沉贯阻力造成影响.针对复合筒型基础的沉放过程, 在粉质黏土中开展了大比尺模型试验.试验中监测了基础舱内压力、周围土体的土压力及孔隙水压力的变化.通过理论计算, 对试验模型沉贯所需负压进行预测, 并将试验施加负压与预测负压进行对比.试验结果表明:基础周围土体土压力和孔隙水压力在负压作用下均减小, 且筒壁内侧土体土压力减小程度大于外侧土体; 沉放过程中基础发生倾斜时, 通过向高舱处抽负压可以有效调整基础的倾斜度; 预测负压大于试验施加负压, 当使用Houlsby提出的计算方法计算筒型基础在粉质黏土中的沉贯阻力时, 摩擦系数建议取0.3.
The penetration of composite bucket foundation is a vital construction process. The soil is disturbed under negative pressure in the process,and both soil pressure and pore water pressure in soil are changed,which affects penetration resistance. A large-scaled model test on the penetration process of composite bucket foundation was carried out in silty clay. During the test,the pressure in compartments,soil pressure and pore water pressure in surrounding soils were monitored. Moreover,the required negative pressure for penetrating was predicated through theoretical calculation,and the negative pressure applied to the test was compared with the predicted negative pressure. The results show that the soil pressure and pore water pressure in the soil around the foundation are both reduced. In addition,the inner soil pressure near the skirt decreases more than the outer soil pressure. When the foundation starts to tilt,the feasibility of bucket tilt adjusting technique is validated by applying suction to higher compartments. The predicted negative pressure is larger than the applied negative pressure in the test. When Houlsby’s method is adopted to calculate the penetration resistance of a bucket foundation in silty clay,the friction coefficient is recommended to be 0.3
交流微网整体建模及仿真研究
,  嵘, 董开松, 沈渭程, 李 臻, 杨 
高压电器 , 2015,
Abstract: 作为消纳新能源发电的一种手段,微电网以其灵活性和经济性,日益受到各国重视。为了研究微电网的运行特性,文中首先研究各分布式电源数学模型,并基于MATLAB/Simulink仿真系统,分别搭建光伏、蓄电池储能系统、柴油发电机的仿真模型,结合系统自带模块,构建了交流微电网的整体性仿真模型。对该系统在多种工况下,各分布式电源出力对系统运行特性的影响进行仿真试验,结果表明,文中所建的交流微电网模型能够准确模拟系统的实际运行情况,为微电网的运行与规划提供了技术支持。
NaYF4∶Er3+,Yb3+纳米晶的液相合成
若琨,杨珊,李翠霞,,白玉白
化学学报 , 2008,
Abstract: 采用丙三醇液相结晶法制备了NaYF4∶Er3+,Yb3+上转换纳米晶,合成步骤被简化.常温下,用980nm的红外激光激发可以观察到很强的绿光、红光发射,用荧光光谱仪记录了该上转换光谱.X射线粉末衍射(XRD)结果表明,该方法制备NaYF4∶Er3+,Yb3+纳米晶属于立方混合六方晶系.研究了纳米晶的上转换发光机理,根据晶体场理论对Er3+的两个上转换能级进行了Stark分裂计算,对两个能级之间的谱线进行了归属,进一步证实了980nm光子激发Er3+离子的上转换机理,一个是连续吸收两个980nm光子的过程(激发态吸收),另一个是吸收980nm光子后,电子转移到亚稳态能级,然后再吸收980nm光子过程(能量转移上转换).
以反复腹泻为主要临床表现的特发性嗜酸性粒细胞增多综合征一例
周强,,刘作凤,林峰洋,成晓敏,
华西医学 , 2015, DOI: 10.7507/1002-0179.20150455
Abstract:
16cm宽体探测器全胸轴扫模式在胸痛三联征检查中的可行性研究
陈玉环,贺太平,,,杨祺,刘振堂
- , 2018, DOI: 10.13609/j.cnki.1000-0313.2018.04.010
Abstract: 【摘要】目的:探讨使用16cm宽体探测器进行两个连续轴位扫描一次完成胸痛三联征检查的可行性。方法:前瞻性将连续40例胸痛三联征患者随机均分为两组:A组采用两个连续心脏轴扫模式一次完成肺动脉、冠状动脉及胸主动脉成像;B组采用三次扫描方案,首先行肺动脉容积扫描,扫描结束8~9s后分别采用心脏轴扫模式和螺旋扫描模式完成冠状动脉和胸主动脉扫描;两组均使用对比剂追踪和阈值触发技术。比较两组图像的图像质量(主观和客观评估)及有效辐射剂量。结果:两种扫描模式图像质量的主观评分和客观评价指标(肺动脉、冠状动脉和主动脉的CT值和对比噪声比)间的差异均无统计学意义(P>0.05)。两个连续轴位单次扫描组的有效辐射剂量为(3.3±1.2)mSv,较常规三次扫描组[(5.6±0.7)mSv]降低40.3%,两组间的差异有统计学意义(t=-3.665,P=0.003)。结论:在胸痛三联检查中采用16cm宽体探测器CT 进行两个连续轴位扫描的单次扫描方案在保障图像质量的条件下,能够有效降低辐射剂量
农牧交错带玉米农田生态系统碳储量变化特征及分布格局
Characteristics and distribution pattern of carbon storage variation of the corn farmland ecosystem in the ecotone between agriculture and animal husbandry

,,王铁军,,,党晓宏,,,陈雅,晨光
- , 2015, DOI: 10.16302/j.cnki.1000-7601.2015.02.035
Abstract: 农田生态系统碳储量变化是陆地碳循环和全球气候变化研究中的一个重要问题。选取我国北方典型农牧交错区当地主要作物玉米为研究对象,对该地区在传统深耕覆膜种植方式下不同时期(翻耕后、幼苗期、成熟期、次年翻耕前)的玉米农田生态系统碳储量及分布格局进行研究。结果表明:在该地区传统耕作方式下玉米农田生态系统地上碳储量显著大于地下碳储量,而土壤碳密度随着土层加深变化规律不明显;单株玉米平均碳含率为43.3%,除根系外,玉米叶片、茎秆有机碳含率变化规律表现为幼苗期>收获期;单株玉米碳储量为收获期>幼苗期;玉米农田生态系统土壤碳密度为收获期>幼苗期>次年翻耕前>翻耕后,土壤碳密度在翻耕后较其他时期显著降低(P<0.05);农田生态系统总碳密度与土壤碳密度变化规律一致。玉米农田生态系统经过一个完整的作物生长季后土壤碳密度在次年翻耕前较前一年翻耕后增加了13 415 kg·hm-2;而作物的碳密度在收获期高达10 974.8 kg·hm-2。由此可见,玉米农田生态系统对大气有明显的固碳减排作用,其“碳汇”能力较强。
Organic carbon storage and sequestration potential change in agricultural soils has been suggested to be an important issue in the study of terrestrial carbon cycling and global climatic change. To study the carbon storage and distribution pattern of corn farmland ecosystem at different stages (after plowing, seeding stage, maturity, before plowing in the next year) in the way of traditional deep-tillage operation and film-mulch planting, the local main crop, corn, was used to conduct the investigation in a typical ecotone between agriculture and animal husbandry in northern China. The result showed that the aboveground carbon storage was obviously higher than the belowground one. The change of soil carbon density was not evidently associated with the depth of soil layer. The average carbon rate of single maize was 43.3%. Except for root, leaf and stalk had higher organic carbon rate at seedling stage than that at maturity stage. And the carbon storage of single maize at maturity was more than that at seedling stage. The soil carbon densities in the corn farmland ecosystem at different stages were in the following order: maturity>seeding stage>before plowing in the next year>after plowing. Soil density after plowing was obviously decreased compared with other stages (P<0.05). The changing law of soil carbon density was the same as the total carbon density of the corn farmland ecosystem. After a whole crop growing season, soil carbon density in the corn farmland ecosystem was increased by 13 415 kg·hm-2 more at the stage before plowing in the next year than that after plowing in the past year, reaching 10 974.8 kg·hm-2. Therefore, corn farmland ecosystem played an obvious role in fixing carbon and reducing discharge to atmosphere, allowing strong carbon sequestration capacity.
新生儿急性单核细胞性白血病一例
Case Report: An Acute Neonatal Monocytic Leukemia
 [PDF]

, 杨帆
Asian Case Reports in Pediatrics (ACRP) , 2013, DOI: 10.12677/ACRP.2013.14017
Abstract: 新生儿先天性白血病由于发病率低,初期白血病的浸润体征不明显,大多患儿是以其他疾病住院后查血常规得到提示后才进一步检查后确诊,国内对先天性白血病化疗的经验非常有限,现就我院发现的一列做报道。
 The incidence of congenital leukemia is rare nationally. The initial signs of leukemia infiltration are usually not indicative, and the diagnosis is largely accidental based on routine blood tests in conjunction with many other examinations after hospitalisation. To date chemotherapy for congenital leukemia is empirical at home with limited choices. Here we report a successful diagnosis and treatment of an acute case of congenital leukemia in our hospital.
我国生态城市建设的时空演化路径及其发展模式
,
哈尔滨工程大学学报 , 2017, DOI: 10.11990/jheu.201609064
Abstract: 为了深入了解我国生态城市建设情况,更好地把握我国生态城市建设进程,通过对2000~2011年期间我国拟建生态城市的数据收集与分析,发现我国生态城市建设的演化进程具有两个明显特征:我国生态城市建设随着时间推移经历了一个离散-集聚-离散的倒U型空间演化过程;我国生态城市的分布具有明显的空间差异性。同时,根据我国生态城市发展的时空演化路径,提出生态城市建设的四个构建模式――空间散点模式、空间集聚模式、空间溢出模式与空间平衡模式。这四个模式是我国生态城市从无到有的发展过程。本文的研究结果可以加深对我国生态城市建设状况的认识,更好地把握我国生态城市建设的进程,从而为生态城市建设的合理开展提供决策参考。
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