Search

The lower reaches of the Minjiang River are located in an area of land-sea-air interaction. It is not only a sensitive area concerning environmental evolution, but also a hotspot for archaeological research on the southeast coast of China. Exploring the scope of ancient human activities and the evolution of land-use patterns is of great significance for understanding the development of human-land relations. By generating various cost surfaces of sites through GIS cost distance analysis and combining with the site catchment theory and method, we comprehensively analyzed the human activity range and land-use pattern in every cultural period from the Neolithic to the Bronze Age in the lower reaches of the Minjiang River and reconstructed the potential population in each period of the region. The results show that: (1) the area of site catchment, available and actually developed land increased from the Keqiutou to Huangtulun culture period in the lower reaches of the Minjiang River. Chronologically, the area of the site catchment continues to grow from 212 km2 to 4,858 km2, the accessible land area increased from 261 km2 to 7,599 km2, and the land area that was actually used by ancient humans continuously increased from 173 km2 to 3,914 km2. (2) With the development process of culture, the land-use intensity of prehistoric humans in the region first increased and then decreased by 81.58%, 92.95%, 87.99%, 79.33% and 80.57%, respectively, and the degree of land development was reduced, which may be related to the development and progress of productive forces. The frequency of ancient human exchanges can be represented by the ratio of the number of sites in the overlapping site catchment to the total number of sites in the same period (87.50%, 60.00%, 66.67%, 92.54%, and 97.81%, respectively). (3) The reconstruction results showed that the potential population in the area continued to expand, with substantial population growth in the lower Tanshishan-Tanshishan and Huangguashan-Huangtulun transitional periods. It was inferred that there was a relationship between population pressure and culture succession.

Prehistoric human cultural sites along the eastern coast of Fujian Province are important records for studying the origin and spread of the Austronesian civilization. The Huangqiyu site is the first Tanshishan culture site to be unearthed in the Min River estuary area and was excavated by scientific archeology. It has great significance for further research of the Tanshishan culture and the coupled relationship between prehistoric human activities and environmental changes in the Fujian coastal region. The chronology of archeological sites is an important foundation for prehistoric archeology. In this study, the burial age of the Huangqiyu site in Lianjiang County was analyzed using the Optically Stimulated Luminescence (OSL) dating technique on the basis of Accelerator Mass Spectrometry (AMS) 14C dating. In the field, the T2 section of the Huangqiyu site was selected for sampling, and the single-aliquot regeneration dose method of medium-grained quartz was used to assess OSL chronology in the laboratory. The results showed that the OSL burial age of the Huangqiyu site ranges from approximately 8.5 ± 0.5 to 4.4 ± 0.2 ka, corresponding to the sedimentary/cultural strata of the early Middle Holocene. The OSL age of sample 2019118, which was consistent with the AMS 14C age, was 4.4 ± 0.2 ka, corresponding roughly to the Tanshishan culture. The age of sample 2019117 was 5.4 ± 0.3 ka, which may be an overestimation because the equivalent dose of this sample showed a weakly skewed distribution with a tail at the high value end, indicating that there was a small amount of sundry particles and that the drying was insufficient. This problem may have led to a bias in the measured equivalent dose and, in turn, to overestimation of the age of the sample. The age of sample 2019119, which was affected by the sampling environment, was 8.5 ± 0.5 ka, possibly indicating the maximum age of the bottom boundary of the site. Archeological studies have found that the age indicated by the pottery features excavated from the cultural layer at the bottom of the Huangqiyu site is most likely earlier than the Tanshishan culture, or possibly that of the lower strata of the Tanshishan culture. Overall, the ages of samples 2019117 and 2019119 are different from the AMS 14C ages, but these are consistent with the archeological characteristics of the site. By comparing the geomorphological and environmental evolution process of the Fuzhou Basin, where the Huangqiyu site is located, with the regional prehistoric human activities, it was found that the site corresponds to the warm climate of 6 500-4 000 a B P and relatively a high sea level period. Many prehistoric remains were developed in the Fuzhou Basin during this period, and the prosperous Tanshishan culture and the lower Tanshishan culture emerged in the region. At the end of the Neolithic age, the abrupt cold event of 4.2-4.0 ka, the drastic change of climate and environment in the tropical and subtropical regions on both sides of the Pacific Ocean at 4 000-3 000 a B P, and the invasion of the northern Wu-Yue culture may explain the disappearance of the follow-up culture. Because of the limited precision of the regional sea-level change curve, it is insufficient to discuss sea-land change and the coupled relationship with human activities. Relevant studies need to strengthen these aspects in the future.

Alluvial-lacustrine deposits are important carriers for studying paleo-hydrological information and the evolution of paleo-environments. In this study, a total of 6 optically stimulated luminescence (OSL) samples from 2 profiles in the lower and middle reaches of the Hutubi River in the North Tianshan Mountains were dated, and a comprehensive analysis was conducted by integrating sedimentary structures, grain sizes, and magnetic susceptibility characteristics to explore the sedimentary environment patterns and regional evolution processes during the Mid to late Holocene. The results revealed the following findings: (1) The OSL signal of quartz samples indicates the predominance of fast components, allowing reliable dating of regional fluvial sediments using the appropriate condition-tested coarse-grained quartz single-aliquot regenerative dose (SAR) protocol within the 90–125 μm range. (2) Analysis of sedimentary structures, grain sizes, and magnetic susceptibility characteristics reveals lithofacies of heterotopic synchronous or homotopic asynchronous in exposed profiles, with predominantly poorly sorted fine and very fine sand. Magnetic susceptibility is primarily controlled by the content of magnetic minerals in the coarse particles, while also being influenced by the combined effects of provenance input and depositional environment, indicating a complex regional sedimentary environment influenced by variable hydrodynamic conditions driven by fluvial processes. (3) Based on OSL dating results and the analysis of various environmental proxy indicators, it is determined that the climatic environment in the Middle and Late-Holocene in the downstream areas of the northern piedmonts of the Tianshan Mountains demonstrates a fluctuating pattern of wet and dry alternations. The sedimentary environment shifted from a stable state in the Mid-Holocene to an unstable state in the Late-Holocene. The intermittent appearance of wet records may be associated with increased river activity caused presumably by the release of high-altitude ice due to rising temperatures and warming conditions. [ABSTRACT FROM AUTHOR]

Aiming at the problems of high performance，high requirements and difficult processing of power electronic device driving pulse signal，a high performance pulse signal processing circuit module is designed and fabricated, and the design is completed by EDA high speed circuit technology. LTspice simulates the circuit system and conducts experimental test. Compared with the domestic research status, the test index has been significantly improved. The high-speed pulse forward rectification of 1 MHz is realized, the output level is controllable, the pulse width adjustment range is 20% to 60%, and the upper and lower edge time is controlled within 25 ns, wherein the falling edge time as low as 13 ns, the transmission delay adjustment range is 20 ns to 110 ns, and the 2 MHz pulse signal indicators are also greatly improved, thereby effectively improving the efficiency of the drive circuit and the main circuit. Further optimizing the selection and layout of the device and adopting a more sophisticated manufacturing process, it is expected to process pulse signals with a frequency of up to 5 MHz, making the power electronic circuit more integrated and efficient.

Many prehistoric sites are preserved in the southeast China coastal area; however, it is still unclear when ancient human activity occurred owing to a lack of chronological evidence, which is unfavourable for research on the coupling of prehistoric man-earth relationships. In this study, we present an optically stimulated luminescence (OSL) chronology analysis of two profiles (T1 and T4) collected from the Neolithic Jianhu (JH) site on Haitan Island, South China. The single-aliquot regenerative-dose (SAR) protocol for coarse silt (38–63 μm) quartz was used to determine the equivalent dose (De). The results showed that the OSL technology is reliable and of great value for archaeochronology in coastal aeolian regions. The results suggest that the JH site is one of the earliest Neolithic sites in the coastal area of Fujian. The ages of cultural layers with ancient human activities at the JH site varied from 7.4 ± 1.13 to 5.77 ± 0.35 ka, thereby making the JH site the earliest Neolithic site in the coastal area of Fujian. The sand-tempered pottery unearthed from the JH site can be used as direct evidence of ancient human survival, and its age is 6.33 ± 0.21 ka with a high precision, which presents the earliest OSL data on pottery in South China. We also discuss the regional environmental background of ancient human activity. The Keqiutou culture corresponds to a period of relatively high sea level and a superior natural environment on Haitan Island. The sea retreat 5.7 ka ago was a crucial factor driving prehistoric human migration to the Fuzhou Basin and Taiwan Island. [ABSTRACT FROM AUTHOR]