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21.
Paweł Lula Octavian Dospinescu Daniel Homocianu Napoleon-Alexandru Sireteanu 《计算机、材料和连续体(英文)》2021,66(3):2425-2443
Our primary research hypothesis stands on a simple idea: The evolution of top-rated publications on a particular theme depends heavily on the progress and maturity of related topics. And this even when there are no clear relations or some concepts appear to cease to exist and leave place for newer ones starting many years ago. We implemented our model based on Computer Science Ontology (CSO) and analyzed 44 years of publications. Then we derived the most important concepts related to Cloud Computing (CC) from the scientific collection offered by Clarivate Analytics. Our methodology includes data extraction using advanced web crawling techniques, data preparation, statistical data analysis, and graphical representations. We obtained related concepts after aggregating the scores using the Jaccard coefficient and CSO Ontology. Our article reveals the contribution of Cloud Computing topics in research papers in leading scientific journals and the relationships between the field of Cloud Computing and the interdependent subdivisions identified in the broader framework of Computer Science. 相似文献
22.
通过现场调研和松动圈观测对望云矿15101工作面沿空煤巷0~450m段破坏进行了统计,得出沿空煤巷顶板偏向煤柱侧及煤柱帮不对称破坏的特点。根据这一特点提出采用偏向煤柱侧布置锚索及增加锚杆长度与直径和增加锚杆索数量的控制方法,在现场试验中取得良好控制效果。 相似文献
23.
Because China has put more emphasis on people with disabilities, their living conditions and protection have received increasing attention. In an emergency, the visually impaired people are limited in their ability to evacuate, especially along egress paths with obstacles. This paper studied the relationship between the travel time of visually impaired people and obstacle density in their path. Eight sighted people and 32 people with visual impairments were chosen to carry out the walking experiment. The results of the experiment showed that the travel time of sighted people was shorter than that of visually impaired people under the same obstacle and non‐obstacle situations. Based on the analysis of variance of travel time, it was clear from the results that the travel time of the visually impaired people rapidly increased when there were obstacles. When the obstacle density was kept to within a certain range, there was no obvious increase in travel time. Once the density exceeded this range, there was another obvious increase. Based on this result, it can be seen that keeping the obstacle density to within a certain range could be helpful for the visually impaired people during an evacuation when the egress paths cannot be made obstacle‐free. 相似文献
24.
熔融制样-X射线荧光光谱法(XRF)测定硅铁合金样品,需重点解决样品前处理中合金样品侵蚀铂-黄坩埚的难题。硅铁样品以四硼酸锂-碳酸锂预氧化剂在石墨垫底瓷坩埚中高温预氧化熔融后,再将熔融物转移至铂-黄坩埚中,用四硼酸锂熔融制成玻璃熔片,实现了熔融制样-X射线荧光光谱法对硅铁合金中硅、磷、锰、铝、钙、铬的测定。实验讨论了预氧化熔融的熔剂体系及氧化方法、试样与熔剂的稀释比,结果表明,试样与熔剂以1∶35的稀释比,以10滴300g/L碘化钾溶液为脱模剂,在1100℃熔融30min,熔融制得的玻璃片均匀、透明、无气泡,符合测定要求。用具有浓度梯度的系列硅铁有证标准样品制作校准曲线,各待测元素校准曲线的线性相关系数均大于0.9995。方法应用于硅铁合金实际样品中硅、磷、锰、铝、钙、铬的测定, 结果的相对标准偏差(RSD,n=11)在0.1%~5.8%之间;正确度试验表明,硅铁标准样品的测定结果与认定值相符,硅铁实际样品的测定结果与国家标准方法测定值一致,能满足常规分析要求。 相似文献
25.
The approach power compensator system (APCS) plays a role in the automatic carrier landing system (ACLS), and the performance of the APCS is affected
by the carrier air-wake in the final-approach . In this paper, the importance of the APCS is verified through the analysis of the signal flow chart of the ACLS.
Hence, it is necessary to suppress the carrier air-wake in order to improve the anti-interference ability. The adaptive sliding mode control (ASMC) not only
has better dynamic tracking performance compared to the nonlinear mode, but also can efficiently resist the disturbance caused by the carrier air-wake.
The design of the longitudinal control law of the ACLS is based on the carrier-based aircraft nonlinear model and the carrier air-wake model. It comprises
the longitudinal guidance rate, autopilot (CAS) and the APCS. The ASMC is used to design the APCS to suppress the carrier air-wake. A comparison of the
simulation results indicates that the design based on the ASMC has better anti-interference ability and can keep the velocity constant on the timely. 相似文献
26.
歧口凹陷歧北次凹沙河街组三段页岩油地质特征与勘探突破 总被引:1,自引:0,他引:1
歧口凹陷歧北次凹沙河街组三段(沙三段)湖泛期细粒沉积发育、烃源岩品质好、页岩油资源丰富,但其研究尚处于起步阶段,在沧东凹陷孔店组二段湖相页岩油工业化开发的带动下,落实其勘探前景势成必然。为探究歧北次凹沙三段页岩油的地质特征及勘探潜力,依据F39X1井、QY10-1-1井等多口井的岩心、分析化验、测井资料和录井资料,对沙三段页岩层系的地质特征、页岩油类型与富集模式、甜点的空间分布规律等开展了综合研究。歧北次凹沙三段的矿物组成和岩石类型多样,主要包括灰质白云质页岩、长英质页岩、混合质页岩及微晶白云岩、亮晶生屑白云岩、粉砂岩等;烃源岩的总有机碳(TOC)含量主要分布在1%~3%,以Ⅱ型干酪根为主且指示热演化成熟度的镜质体反射率(Ro)普遍高于0.7%;储集空间主要包括粒间孔、晶间孔、生物体腔孔、有机孔及层理缝、构造(微)缝等;页岩油的超越效应明显(油饱和度指数平均为116.3 mg/g)、荧光显示良好。在歧北次凹沙三段中识别出单一型和夹层型2类页岩油,构建了高TOC滞留型页岩油和低TOC运移型页岩油2种富集模式,并建立了基于油饱和度指数、TOC和脆性指数等多参数的甜点定量评价方法及标准。针对甜点区部署了QY10-1-1水平井,其初期的折算产油量达103.5 t/d,预计可形成亿吨级增储新领域。勘探发现证实歧口凹陷的沙三段细粒岩段具备良好的页岩油勘探潜力。 相似文献
27.
As the standard of living constantly improves, and as life expectancy increases in developed countries, the number of adults who want to have a gratifying life increases as well. Furthermore, although the Internet offers a world of potentially rewarding experiences, there is much heterogeneity among older people with respect to those who are able to benefit from its use. To reduce this gap, public access and digital literacy programs have been implemented. The aim of the study was to find out the extent to which these programs moderate the effects of age and socioeconomic status on social access to and use of the Internet in a sample of older users in Spain. Through quota sampling of retired users over 54 years of age in Spain (N = 560), who were regular users of public supports for Internet access, a structural equation modeling and multi-group analysis was conducted. The data showed a staggered association of access indicators (physical access, digital skills and social e-activities) on the social gratifications obtained, as well as the moderating role of institutional supports. This study provides empirical evidence of the ability of public supports to moderate the effect of socioeconomics inequalities on access and social exploitation of the Internet by older people. The findings point to the need to strengthen digital literacy actions, especially in supports that are more sensitive to the effect of age and socio-economic status. 相似文献
28.
29.
本文主要讨论衡器的检定分度数能否大于传感器的最大检定分度数nmax,这是一直困扰大家和争论不休的问题。作者由分析最大允许误差mpe本质入手,指出mpe是人为规定的误差,不是传感器实际的物理特性。通过理论分析得出的对单只传感器的衡器,n≤nmax和v≥vmin的误差限原则是不能违背的。对于四只传感器的衡器,不受上述误差限原则限制。 相似文献
30.
本文分为两个部分,第一部分简述了比利时在不同时期的建筑遗产保护实践,主要包括:第二次世界大战后的战后重建,威尼斯宣言颁布前后的相关实践,1975年"欧洲建筑遗产年"后对"历史文物古迹"的保护延伸到对次要建筑群及其所处环境以及历史城市、村镇的整体性保护,1988年文化遗产保护管理从比利时联邦下放到弗兰芒、瓦隆、布鲁塞尔三区实行分区管理等方面;第二部分着重介绍了比利时在建筑遗产的预防性保护这块的实践,以"文物古迹监护"机构近30年的实践为例,并试图从历史、社会、经济、管理、教育等角度对预防性保护得以成功实施的原因进行了分析。 相似文献