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Search Results: 1 - 10 of 248619 matches for " 李卓然 "
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云南省CPI序列的分析与预测—基于SARIMA模型
Analysis and Prediction of Yunnan CPI Series—Based on SARIMA Model
 [PDF]

卓然, 孙晓宇
Statistics and Applications (SA) , 2016, DOI: 10.12677/SA.2016.52015
Abstract: 本文以云南省为例,运用近20年来的月度数据对CPI进行建模预测。分析表明,CPI数据呈现周期为12的季节性;文章通过建立季节性ARIMA模型,预测2016年第二季度云南省CPI将在第一季度的基础上逐渐上升,且能够保持在稳定增长的范围内。
Taking Yunnan Province as an example, monthly data nearly 20 years were used on CPI forecast modeling. Analysis shows that the CPI data present seasonal cycle of 12. Through the establishment of the seasonal ARIMA models in this article, we predict the CPI of Yunnan Province in 2016 in the second quarter will gradually rise on the basis of the first quarter. And it is able to maintain within the scope of stable growth.
Maximizing empower of Spartina alterniflora community.
互花米草群落功率最大化倾向

王金丽,卓然,钦佩
应用生态学报 , 2010,
Abstract: When a new plant species is introduced to a new district, its disturbance could alter the structure of original ecosystem, resulting in the formation of a distinctive self-organized ecosystem to develop the maximizing empower under the new situation. In this paper, an emergy analysis method was made on the two ecosystems Spartina alterniflora salt marsh and mudflat in North Jiangsu. Compared with the mudflat, S. alterniflora ecosystem had a 1.52E+18 sej higher annual total emergy output, 4.72 times of emergy density, and about 5 times of base emergy yield ratio. S. alterniflora ecosystem could use the energy more efficiently to increase its emergy storage and to realize it self’s empower maximizing. After invading into a tidal flat ecosystem, S. alterniflora via self organization could promote the ecosystem to achieve empower maximizing, and to full play its ecological services. However, too fast propagation and spread could induce a series of negative effects, such as inhibiting native plants, trenching on sea-route, and endangering the seashells breeding, etc.
互花米草群落功率最大化倾向
王金丽,卓然,钦佩
应用生态学报 , 2010,
Abstract: 植物新种进入新区域后,通过扰动或搅局,改变生态系统的结构,形成有特色的自组织生态系统,趋向新条件下的功率最大化.本文应用能值分析的方法,分别对苏北互花米草生态系统和光滩生态系统进行能值分析和系统评估.结果表明:互花米草生态系统每年能值产出比光滩生态系统高1.52e+18sej.能值密度是光滩的4.72倍,基础能值产出率约为光滩生态系统的5倍.互花米草生态系统能更有效地利用能量,增加系统内部的能值贮存,实现系统内部的功率最大化.互花米草入侵某区域滩涂后,通过自组织促使整个互花米草生态系统趋于功率最大化,充分发挥生态服务功能,但由于其繁殖扩散过快,导致种群爆发,产生了一系列负面效应,如抑制本土物种、侵占航道、危害贝类养殖等.
氧化铝陶瓷与低碳钢钎焊接头的界面反应
卓然,樊建新,冯吉才
材料工程 , 2008,
Abstract: 采用真空保护下的活性金属钎焊法对95%(质量分数)氧化铝陶瓷与低碳钢进行了钎焊,所用钎料为Ag-Cu-Ti3活性钎料.通过X射线衍射仪(XRD)对界面的反应产物进行了物相分析,并用能谱仪(EDAX)分析了界面元素组成.结果表明,钎焊接头界面的反应十分复杂,反应产物多种多样,主要是Ti3Cu3O,Ti3Al,TiMn,TiFe2,TiC等物质,界面的反应层按Al2O3陶瓷/Ti3Cu3O/Ti3Al+TiMn+TiFe2+Ag(s,s)+Cu(s,s)/TiC/低碳钢的规律过渡.
SiC陶瓷真空钎焊接头显微组织和性能
冯广杰,卓然,朱洪羽,徐慨
材料工程 , 2015, DOI: 10.11868/j.issn.1001-4381.2015.01.001
Abstract: 在高真空条件下采用Ti-35Zr-35Ni-15Cu(质量分数/%)钎料对SiC陶瓷进行了钎焊连接,研究了接头界面组织的形成过程以及工艺参数对接头性能的影响.结果表明钎料与SiC陶瓷发生了复杂的界面反应,生成了多种界面产物.当钎焊温度为960℃,保温时间为10min时,SiC陶瓷侧形成了连续的TiC和Ti5Si3+Zr2Si层,同时Ti5Si3+Zr2Si向钎缝中心生长呈长条状.SiC陶瓷到接头钎缝中心的显微组织依次为SiC/TiC/Ti5Si3+Zr2Si/Zr(s,s)/Ti(s,s)+Ti2(Cu,Ni)/(Ti,Zr)(Ni,Cu).钎焊温度为960℃,保温时间为30min时,长条状的Ti5Si3+Zr2Si贯穿了整个接头.钎焊接头强度随着钎焊温度的升高和钎焊时间的延长都呈现先增大后减小的趋势.当钎焊温度为960℃,保温时间为10min时,接头的剪切强度最高,达到了110MPa.
ZrB2-SiC钎焊接头界面产物及反应层生长规律
卓然,徐晓龙,王征征
材料工程 , 2013, DOI: 10.3969/j.issn.1001-4381.2013.12.008
Abstract: 采用TiZrNiCu非晶活性钎料进行ZrB2-SiC复合陶瓷的真空钎焊连接,通过电子扫描显微镜、能谱分析仪及X射线衍射分析仪,分析钎焊过程接头界面反应产物,阐述产物形成机理。利用扩散理论,结合Ti元素在固溶体层的扩散行为,对界面中复合材料侧形成的Zr(s,s)固溶体层进行动力学分析,得到了描述Zr(s,s)固溶体层生长行为的动力学方程。
ZrB2高温陶瓷钎焊接头的界面组织和性能
卓然,王征征,吴广东,朱晓智
材料工程 , 2010,
Abstract: 采用Ti-Zr-Ni-Cu钎料对ZrB2-SiC陶瓷的真空钎焊工艺进行研究。借助SEM,EDS和XRD等分析测试手段,分析了接头的界面组织结构及性能。实验结果表明接头界面产物主要有TiC,ZrC,Ti5Si3,Zr2Si,Zr(s,s),(Ti,Zr)(Ni,Cu)等。随着钎焊温度和钎焊保温时间的增加,钎焊接头中的Zr(s,s)层厚度不断增加,焊缝两侧灰色相Ti5Si3+Zr2Si的体积和数量逐渐增加并向焊缝中部生长伸展,焊缝接头中的黑色相TiC+ZrC的体积和数量明显增加,其分布贯穿整个焊缝。当钎焊温度为920℃,钎焊时间为10min时,钎焊接头的抗剪切强度最高,达到143.5MPa。
矢状位平衡影像学评价之争议与现状
The disputes in the radiographic measurements of sagittal balance and how to deal with them

周思宇,卓然,危石
- , 2018, DOI: 10.7507/1002-1892.201808080
Abstract: 目的 对骨盆-脊柱矢状位平衡的影像学评价现状及争议展开综述,为其在临床的合理应用提供参考。 方法 广泛查阅国内外关于骨盆-脊柱矢状位参数及其临床应用的相关文献,从目前常用的各项参数的临床应用、各自的优点和局限性、如何合理运用这些参数等方面进行总结。 结果 矢状位参数各有其优缺点,而且受种族、年龄影响。脊柱矢状轴仅能反映整体情况,T 1 骨盆角综合了躯干倾斜和骨盆代偿信息,但在术中不易控制,而西方人群的矫形目标可能不适合于中国人群。 结论 在评估矢状位平衡时需合理运用各参数的优势,衡量整体平衡时也需考虑局部情况,而且对于不同人群需要采用不同的评价标准。
Objective To review the process of radiographic measurements of sagittal balance and offer reference for the clinical practice. Methods The related literature of spino-pelvic sagittal parameters and their clinical application was reviewed and analyzed from the aspects such as the clinical application, the advantages and disadvantages, and how to use them effectively. Results All parameters have their advantages and disadvantages, and they are influenced by age and race. Sagittal vertical axis can only reflect the global balance, and T 1 pelvic angle which accounts for both spinal inclination and pelvic tilt can’t be controlled in the surgery. The correction goal for western people may be not suitable for Chinese. Conclusion The parameters should be used wisely when evaluating the sagittal balance, the global balance and local balance should be considered together and the different groups of people need different correction goals.
离子探针分析中动态沾污离子及其质谱特征的揭示
卓然
科学通报 , 1982,
Abstract: 一、引言在离子探针(动态SIMS)质谱分析中,动态沾污离子的来源及其质谱特征是一个长期以来为人们所注意的基本课题.当分析是金属或半导体的样品时,在目前二次离子质谱仪器一般能达到的分辨率条件下,这些沾污干扰离子往往与成份离子重叠在一起,很难辨认.有些
用负离子轰击作非导体离子探针分析
卓然
科学通报 , 1981,
Abstract: 一、引言非导体样品分析是离子探针质谱微分析应用中一个重要技术课题,因为它关系到这门先进分析技术能否在许多本身涉及非导体的学科如材料、地质、化工、生物、医学中获得应用的问题。非导体样品在离子的轰击下发生的表面局部荷龟效应会给予二次离子的发射和接收以严重的影响,甚至使分析工作无法进行。目前人们在原则上提出了解决这个问题的三个主要途
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