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结合频谱与曲轴转角域的发动机敲缸异响分析 被引量:3
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作者 洪日昇 王越 《传动技术》 2020年第2期24-28,共5页
针对某型号发动机的敲缸异响,提出一种简便,快速和有效的诊断分析方法。首先对异响频谱滤波降噪,通过声音回放确定特征带宽,使用带有TDC信号的曲轴转速作转角跟踪分析,结合气缸的工作冲程与曲轴转角的关系,判断异响源。最后通过零件换... 针对某型号发动机的敲缸异响,提出一种简便,快速和有效的诊断分析方法。首先对异响频谱滤波降噪,通过声音回放确定特征带宽,使用带有TDC信号的曲轴转速作转角跟踪分析,结合气缸的工作冲程与曲轴转角的关系,判断异响源。最后通过零件换装试验,验证了该方法的有效性。 展开更多
关键词 发动机异响 敲缸 频谱分析 异响特征 曲轴转角
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Basic Characteristics,Spatial Disparity and Its Major Influencing Factors of Service Industry in China 被引量:6
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作者 SHEN Yuming QIU Ling +3 位作者 REN Wangbing CAO Yi HU Dan SONG Yujing 《Chinese Geographical Science》 SCIE CSCD 2009年第4期314-324,共11页
Based on the analysis of its basic characteristics, this article investigated the disparities of Chinese service industry among the three regions (the eastern China, the western China and the middle China) and inter... Based on the analysis of its basic characteristics, this article investigated the disparities of Chinese service industry among the three regions (the eastern China, the western China and the middle China) and inter-provincial disparities of that in the three regions by Theil coefficient and cluster analysis. Then, major factors influencing its spatial disparity were explored by correlation analysis and regression analysis. The conclusions could be drawn as follows. 1) The development of Chinese service industry experienced three phases since the 1980s: rapid growth period, slow growth period, and recovery period. From the proportion of value-added and employment, its development was obviously on the low level. From the composition of industrial structure, traditional service sectors were dominant, but modem service sectors were lagged. Moreover, its spatial disparity was distinct. 2) The level of Chinese service industry was divided into five basic regional ranks: well-developed, developed, relatively-developed, underdeveloped and undeveloped regions, As a whole, the overall structure of spatial disparity was steady in 1990-2005. But there was notable gradient disparity in the interior structure of service industry among different provinces. Furthermore, the overall disparity expanded rapidly in 1990-2005. The inter-provincial disparity of service industry in the three regions, especially in the eastern China, was bigger than the disparity among the three regions. And 3) the level of economic development, the level of urban development, the scale of market capacity, the level of transportation and telecommunication, and the abundance of human resources were major factors influencing the development of Chinese service industry. 展开更多
关键词 service industry Theil coefficient Pearson correlation coefficient cluster analysis spatial disparity China
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Characteristics of Far-field Precursory Anomalies Before the M_S8.1 Earthquake in the West of Kunlun Mountains Pass
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作者 Chen Yuhua Dong Zhiping +1 位作者 Wang Peiling Li Yongqiang 《Earthquake Research in China》 2009年第3期354-371,共18页
In this study, a number of typical precursory anomalies recorded by stations in Qinghai, Gansu, Sichuan, Xinjiang, Ningxia, Hebei and Shaanxi provinces and autonomous regions before the Ms8.1 earthquake in the west of... In this study, a number of typical precursory anomalies recorded by stations in Qinghai, Gansu, Sichuan, Xinjiang, Ningxia, Hebei and Shaanxi provinces and autonomous regions before the Ms8.1 earthquake in the west of Kunlun Mountains Pass are collected and checked. According to the standards of earthquake cases in China, the criteria of the precursory anomalies are determined, and 53 distinguished. The characteristics of these anomalies before the Ms S. 1 earthquake are analyzed, with results showing a very large earthquake affected area. The precursory anomalies recorded by instruments were 2900 km away from the epicenter, and according to the study in this paper, reached 2100 km away. The results also show that the anomalies present characteristics of long duration, multi-measurement items and large-amplitude variation. The authors believe that in large earthquake monitoring, attention should be paid to the variation of data over a large area, ranging up to thousands kilometers, with much denser earthquake observation networks. 展开更多
关键词 West of Kunlun Mountains Pass Ms8.1 earthquake Typical precursoryanomalies Analysis of anomaly characteristics
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Spatial and Temporal Distribution Characteristics of Flower-viewing Tourism and Its Influencing Factors in China 被引量:1
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作者 WANG Lu ZHOU Linjie +1 位作者 TANG Chengcai NING Zhizhong 《Journal of Resources and Ecology》 CSCD 2022年第4期746-758,共13页
Despite the rapid development of flower-viewing tourism in China in recent years,there is almost no systematic research on it.Therefore,this study analyzes the spatial and temporal distribution characteristics of flow... Despite the rapid development of flower-viewing tourism in China in recent years,there is almost no systematic research on it.Therefore,this study analyzes the spatial and temporal distribution characteristics of flower-viewing tourism and its influencing factors in China using the spatial statistical analysis methods and the geographic detector method.The study uses the Point-of-Interest data of flower-viewing tourist attractions from networks such as Qunar and Ctrip,the flower observation data from China Phenological Observation Network,Chinese network news,and Weibo,and the statistical data from yearbooks.The results are as follows:1)The spatial attribution type of flower-viewing tourism in China is aggregated into areas,including two high-density aggregated areas,three medium-density aggregated areas,and one general-density aggregated area.Furthermore,five major types of flower-viewing tourist attractions have formed several aggregated areas.2)The time of flower viewing in China starts from about February and lasts about eight months till October each year.Florescence and flowering time of different ornamental flowers in different regions are different.3)The spatial and temporal distribution characteristics of flower-viewing tourism in China are mainly affected by ornamental flower phenology,spatial distribution characteristics of flower-viewing resources,regional permanent population size,youth population size,female population size,regional GDP,and added value of the tertiary sector.These conclusions clarify the spatial and temporal distribution characteristics of flower-viewing tourism and its influencing factors in China.They could provide a scientific basis and useful reference for the coordination and sustainable development of regional flower-viewing tourism in China. 展开更多
关键词 flower-viewing tourism influencing factors spatial and temporal distribution characteristics tourist attractions
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