The rock-cut tomb and cist burial culture prevailed once in ancient southwest China.There have long been many discrepancies of views on its origin, evolution, periodization and ethnic attribution in academic circles. ...The rock-cut tomb and cist burial culture prevailed once in ancient southwest China.There have long been many discrepancies of views on its origin, evolution, periodization and ethnic attribution in academic circles. Based on an analysis of the pottery flat-bottomed amphoras that constitute its major characteristic feature, the present paper points out that these typical vessels were roughly distributed in the upper Minjiang River valley, western Sichuan, eastern Tibet, northwestern Yunnan, southwestern Sichuan, and the areas to the west of the Dianchi Lake and to the east of the Erhai Lake. Most of the amphoras recorded so far are unearthed from rock-cut and cist tombs while a small number from earthen-pit,brick-and-stone and brick-chambered burials. Those found in Yunnan are from earthen-pit and cist tombs. Through a systematic study of their typological classification, periodization and origin, the author comes to the conclusion that the emergence of these vessels resulted from the constant southward migration of nomads belonging to the Di-Qiang ethnic group in northwest China. The starting point of these vessels can be traced to the turn from the Xia to the Shang period. Latter, with the amalgamation of ethnic groups and the formation of a plural national unity in the Han Dynasty, these immigrants gradually changed their way of life from husbandry to settled farming, and in southwest China early-style flat-bottomed amphoras became extinct little by little. Therefore their lower limit was the Eastern Han period. Thus they were out of prevalence in the Eastern Han period. The above-described amphoras fall roughly into five types and further into several subtypes and styles, which represent respective temporal and spatial links of their evolutionary sequence. Their proto-type and similar forms must have originated from the Keshengzhuang Ⅱ, Qijia, Siba, and Kayao cultures in the northwest China. The cultural source and ethnic attribution of early-style flat-bottomed amphoras in the southwest China reflect clear展开更多
Due to its high efficiency, high precision and high flexibility, CNC lathe is widely used in the machinery manufacturing industry increasingly, and becomes one of CNC machine too[s that most widely used. However, to g...Due to its high efficiency, high precision and high flexibility, CNC lathe is widely used in the machinery manufacturing industry increasingly, and becomes one of CNC machine too[s that most widely used. However, to give full play to the role of CNC lathes, the key is programme, that is, preparing the reasonable and efficient processing procedures depending on the features and precision parts. This paper discussed the problems of programming and processing techniques of the CNC lathe parts.展开更多
文摘The rock-cut tomb and cist burial culture prevailed once in ancient southwest China.There have long been many discrepancies of views on its origin, evolution, periodization and ethnic attribution in academic circles. Based on an analysis of the pottery flat-bottomed amphoras that constitute its major characteristic feature, the present paper points out that these typical vessels were roughly distributed in the upper Minjiang River valley, western Sichuan, eastern Tibet, northwestern Yunnan, southwestern Sichuan, and the areas to the west of the Dianchi Lake and to the east of the Erhai Lake. Most of the amphoras recorded so far are unearthed from rock-cut and cist tombs while a small number from earthen-pit,brick-and-stone and brick-chambered burials. Those found in Yunnan are from earthen-pit and cist tombs. Through a systematic study of their typological classification, periodization and origin, the author comes to the conclusion that the emergence of these vessels resulted from the constant southward migration of nomads belonging to the Di-Qiang ethnic group in northwest China. The starting point of these vessels can be traced to the turn from the Xia to the Shang period. Latter, with the amalgamation of ethnic groups and the formation of a plural national unity in the Han Dynasty, these immigrants gradually changed their way of life from husbandry to settled farming, and in southwest China early-style flat-bottomed amphoras became extinct little by little. Therefore their lower limit was the Eastern Han period. Thus they were out of prevalence in the Eastern Han period. The above-described amphoras fall roughly into five types and further into several subtypes and styles, which represent respective temporal and spatial links of their evolutionary sequence. Their proto-type and similar forms must have originated from the Keshengzhuang Ⅱ, Qijia, Siba, and Kayao cultures in the northwest China. The cultural source and ethnic attribution of early-style flat-bottomed amphoras in the southwest China reflect clear
文摘Due to its high efficiency, high precision and high flexibility, CNC lathe is widely used in the machinery manufacturing industry increasingly, and becomes one of CNC machine too[s that most widely used. However, to give full play to the role of CNC lathes, the key is programme, that is, preparing the reasonable and efficient processing procedures depending on the features and precision parts. This paper discussed the problems of programming and processing techniques of the CNC lathe parts.
