On the beginning of the Japanese Upper Paleolithic:A review of recent archaeological and anthropological evidence

The beginning of the Japanese Upper Paleolithic has mainly been examined using two major models:the Middle Paleolithic evolutionary model within the archipelago and the continental Upper Paleolithic diffusion/migration model.However,recent archeological data from Japan and nearby countries are challenging such simple models.This paper critically reviews previous chronology of the Japanese Paleolithic,including possible Lower and Middle Paleolithic(LP/MP),and attempts to show an alternative model of the beginning of the Japanese Upper Paleolithic.This paper suggests several possible specimens of LP/MP and recommends further geoarchaeological investigation to understand the reliability and cultural relationship between possible LP/MP specimens and the Early Upper Paleolithic(EUP).The start of the Japanese EUP is presently characterized by a flake industry with trapezoids and denticulates around 39-37 kaBP cal on Paleo-Honshu Island,which has partial resemblance with contemporary assemblages in China and the Korean Peninsula,although trapezoids are endemic only to the Japanese EUP and may have derived from the ancestral lithic tradition.Blade technology appeared earliest on Central Paleo-Honshu Island,about 1000 years later than the earliest flake technology.Although blade technology may have originated from the elongated flake technology of the previous period,the sudden simultaneous emergence implies that it diffused from the Korean Peninsula.This paper proposes that blade technology from the Korean Peninsula arrived on the northeastern Paleo-Honshu Island,including the Japan Sea coastal region of western Honshu,rather than the southwest,where flake technology long prospered,due to differences in ecological settings and adaptation strategies between the two regions.

Technology diffusion and population migration reflected in blade technologies in northern China in the Late Pleistocene

In recent years, the origin and evolution of modern human behaviors have become a common topic of research in Paleolithic archaeology. One important part of modern human behavior, blade technology, was once thought to be unique to modern humans. Recent studies have suggested that variations in blade technology do not fully correspond to modern populations. However, the standardization, diversity, discontinuity in terms of time distribution, and differences in spatial distribution of blade technology give it an important role in discussions of modes of adaptation, diffusion of technology, and population migration of hominins. By categorizing the major blade assemblages in China, we show that there were two blade reduction methods in northern China: the Levallois method and the prismatic method. Dating back 40000–30000 years, the Levallois and prismatic blade method combined to form the characteristics of the early stage of the Upper Paleolithic. Artifacts bearing such characteristics are located in Northwest China, Northeast China, and the Qinghai-Tibet Plateau. The unearthed blades are similar in technological organization and are connected geographically with those discovered in Siberia and Mongolia, which also indicates a distinct border from those discovered in northern China. This fact is suggestive of population immigration. About 29000–25000 years ago, a combination of prismatic blades and microblades was developed in the hinterland of China; however whether it can be regarded as the representative of population migration or only a technological adaption remains undetermined. We suggest that the system of production of different blades should be distinguished in the study of blade assemblages and that different blade methods should not be integrated into a single technical system to discuss technology diffusion and population dispersal.

Hot Deformation Behavior of GH738 for A-USC Turbine Blades

The hot deformation characteristics of GH738 superalloy over the temperature range of 1000 °C to 1 200 °C and strain range of 0.01 s^-1 to 10.0 s^-1 under a strain of 1.0 s^-1 were investigated through hot compression tests with a Gleeble-1500 simulation machine. The flow stress reached peak value before flow softening occurred. The average apparent activation energy（Q） of GH738 was calculated to be 430 k J/mol, and the stress index（n） is approximately 4.08. The processing map was developed based on flow stress data and dynamic materials model（DMM）. The map shows a dynamic recrystallization（DRX） domain in 1 050 °C to 1150 °C and 0.01 s^-1 to 1.0 s^-1 strain rate range with a peak efficiency of 45%, which is considered to be the optimum region for hot working. Moreover, the materials undergo flow instability in the temperature range of 1000 °C to 1050 °C and strain range of 1.0 s^-1 to 10.0 s^-1, and adiabatic shear bands can be observed in this domain.