No abstract

Summary Interactions among an inerter, spring, and energy dissipation element (EDE) in an inerter system can result in a higher energy dissipation efficiency compared to a single identical EDE, which is referred to as the damping enhancement effect. Previous studies have mainly concentrated on the vibration mitigation effect of the inerter system without an explicit consideration or utilization of the damping enhancement mechanism. In this study, the theoretical essence of the damping enhancement effect is discovered, and a universal design principle is proposed for an inerter system. A fundamental equation is found and demonstrated on the basis of closed‐form stochastic responses, which establishes a bridge between the damping deformation enhancement factor (DDEF) and the response mitigation ratio, thus clarifying the relationship of the damping enhancement effect and the response mitigation effect. Inspired by the equation, a novel damping‐enhancement‐based strategy is proposed to determine the key parameters of an inerter system. Following the performance‐demand‐based design philosophy, the parameters of the inerter system can be determined in the design condition of a target‐damping‐enhancement effect. Through the implementation of the damping enhancement equation, the damping parameter of an inerter system can be directly obtained by the prespecified DDEF and the displacement response mitigation ratio. The influence of parameters on the response mitigation effect and the damping enhancement effect is then investigated to determine ways of obtaining the other two parameters in an inerter system. Finally, design examples are conducted to verify the proposed strategy and the theoretical relationship revealed by the damping enhancement equation. The results show that the proposed design strategy explicitly utilizes the damping enhancement effect for vibration control, where the target of the DDEF is effective in enhancing the efficiency of the EDE for energy dissipation. In the design condition of the target DDEF, the implementation of the proposed damping enhancement equation provides an inerter system with a practical equation to determine the key parameters of an inerter system in a direct manner.

The emergence and rapid spread of agriculture from the early Holocene has made a great impact on the development of human societies and landscape change. Guanzhong Basin in the middle of Yellow River valley has a long continuous history of agriculture since the Neolithic. The pollen and charcoal records from Xindian in western Guanzhong Basin, together with the known distribution of archaeological sites, provide proxies to reconstruct the history of agricultural activity and landscape change. The concentration and percentage of Poaceae pollen increase from about 7700 yr BP ago and the concentration of charcoal shows the same trend. These records indicate that the ‘slash-and-burn’ cultivation for agriculture began around 7700 years ago. Between 7700 and 5500 yr BP, the evidence of cereal crops remained strong and charcoal concentration and archaeological sites increased greatly, which all indicate increased agricultural activity and the expansion of human populations. This was enhanced by the continuous development of new cultivation tools and techniques between 4700 and 3300 yr BP, especially in the Bronze Age of the pre-Zhou Dynasty. The original agricultural landscape had been settled after 3300 yr BP. Buckwheat became an important crop from around 5500 yr BP, perhaps because of increasing aridity. This is the earliest record of cultivated buckwheat in Neolithic China.

The crop types and agricultural characteristic are reconstructed using the archaeobiological proxies of pollen, seed and phytolith at Xishanping site in Gansu Province between 5250 and 4300 cal a BP. The agricultural activity strengthened in Xishanping from 5100 cal a BP. It appeared the earliest cultivation of prehistoric rice in the most northwest China at 5070 cal a BP. The sudden disappearance of conifers and expansion of chestnut trees is likely to be the result of selective hewing of conifers and cultivation of chestnuts at about 4600 cal a BP. There existed 8 crop types of foxtail millet, broomcorn millet, rice, wheat, barley, oats, soybean and buckwheat at Xishanping between 4650 and 4300 cal a BP, which cover the main crop types of the two origin centers of East and West Asia. Not only has the wheat and barley been approved to spread to northwestern China, but the earliest complexity agriculture in Neolithic China appeared in Tianshui, Gansu Province. archaeobiological proxy, broadening agriculture, Xishanping site, Gansu Province, 4650 cal a BP The Anthropocene as an individual geological episode containing special signification and content was suggested a new geological era [1,2] that is extracted from the Holocene of 10000 years [3] , in which humans have impact on the natural behavior of the Earth [1][2][3][4] . The further study on the Anthropocene will help us to discuss the characteristic of human activities especially the prehistoric agriculture that resulted in the changes of land, vegetation, and atmosphere and attend the naissance, conflicting, blending, and development of civilization [1,[4][5][6] .The climate fluctuation from the last deglaciation altered the survival state of humans in most regions in the world. The maladjustment between the population and natural resources stressed the prehistoric hunting-gathering humans to adopt the environmental change for survival using the new technology [7,8] . The agriculture, as one of the most important events appearing in the early Neolithic and developed rapidly [8][9][10][11][12][13] , is the most important economic activity in prehistoric society and the base of the forming and developing of civilization. Now, the biological evidence of the human agricultural activity became one of the significant studies of Anthropocene to reconstruct the agricultural history in different regions, and the economic movement and population growth and expansion were discussed. The records of archaeological proxy will help us to discuss the exchanging and blending of different cultures triggered by the agriculture expanding and spreading and to explore the contribution of agriculture activity to the naissance

The two cultivated species of buckwheat, Fagopyrum esculentum (common buckwheat) and F. tataricum (Tartary buckwheat) are Chinese domesticates whose origins are usually thought to lie in upland southwestern China, outside the major centres of agricultural origins associated with rice and millet. Synthesis of the macro-and microfossil evidence for buckwheat cultivation in China found just 26 records across all time periods, of which the majority were pollen finds. There are few or no identifying criteria distinguishing F. esculentum and F. tataricum for any sample type. The earliest plausibly agricultural Fagopyrum occurs in northern China from the mid 6th millennium cal bp. The archaeobotanical record requires reconciliation with biogeographic and genetic inferences of a southwestern Chinese origin for buckwheat. Scrutiny of the genetic data indicates limitations related to sampling, molecular markers and analytical approaches. Common buckwheat may have been domesticated at the range margins of its wild progenitor before its cultivation expanded in the north, mediated by changing ranges of wild species during the Holocene and/or by cultural exchange or movement of early agriculturalists between southwest China, the Chengdu Plain and the southern Loess Plateau. Buckwheat probably became a pan-Eurasian crop by the 3rd millennium cal bp, with the pattern of finds suggesting a route of westward expansion via the southern Himalaya to the Caucasus and Europe.

No abstract

No abstract

Research in to the nature of Neolithic agriculture in China is often focused on topics such as the domestication and spread of cereal crops and the reconstruction of human and animal diets in the past. Field management practices, such as organic manuring, have not been systematically investigated in Chinese archaeology. Here we present an isotopic dataset for archaeological foxtail millet (Setaria italica) and common millet (Panicum miliaceum) grains as well as associated faunal remains (both domesticated and wild) from seven sites in the Baishui Valley of north China, in order to find direct evidence of organic manuring during the Late Neolithic period. The elevated nitrogen isotope values of the millet grains (5500-3500 cal BP) in comparison with the estimated local vegetation indicates that millets were organically manured by animal dung, mostly likely originating from domestic pigs. Considering the low nitrogen contents of loess soils and their unsuitability for intensive cultivation, this organic manuring by animal dung would have played a key role in maintaining soil productivity and crop yield, which was necessary to support the demands of agriculture and cultural expansion during the Late Neolithic on the Loess Plateau of China.