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New Aconitine-Type $C_{19}-Diterpenoid$ Alkaloids from Aconitum hemsleyanium var. circinacum
Gao, Feng,Chen, Dong-Lin,Wang, Feng-Peng 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.12
Two new aconitine-type $C_{19}-diterpenoid$ alkaloids, hemsleyanines C (1) and D (2), were isolated from the roots of Aconitum hemsleyanium var. circinacum, their structures were determined by the chemical evidence and spectral analyses.
Robust Recommendation Algorithm based on Metadata Fusion
Gao Feng 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.6
The metadata information of users and items for enhancing the recommendation system robustness has important valuable. Following this design philosophy, this paper first presents the user suspects assessment strategy based on Probabilistic Latent Semantic Analysis, the user suspected sexual and generic items such as meta-information to model parameters and Logistic Regression way into Bayesian probabilistic matrix factorization (BPMF) model, and then proposes Metadata-enhanced Variational Bayesian Matrix Factorization (MVBMF), designed a model of incremental learning strategy based on robust linear regression, in order to reduce the demand for model rebuilding. Experimental results show that MVBMF can effectively defend against shilling attacks and also has a high level of performance for strong and weak generalization.
Study on Ethnic Channels and the Spread of Wheat in China from the Perspective of Crop Anthropology
Dai Gaofeng(Gaofeng Dai) 아시아사회과학학회 2022 Jornal of Asia Social Science Vol.8 No.1
The spread of wheat from West Asia to China has experienced a long time and complicated paths. In particular, the plant archaeological studies reveal that the spread of wheat in China presents the phenomenon of time-space inversion and multi-point synchronization, which makes it difficult to justify the description of the simple linear path of wheat spread from west to east. From the perspective of crop anthropology, the spread of wheat is based on the combination of factors including climate change, physical and geographical conditions, farming techniques and cultural exchanges. The discussion on the spread track of wheat in China should integrate archaeological remains, natural conditions, livelihood style, ethnic communication, cultural changes, etc. From the perspective of nationalities and ethnic groups, the flow of people and cultural exchange should be put in the first place. The Eurasian steppe channel and the Silk Road are the two ethnic channels through which wheat spreads to China. First of all, wheat spread from eastern Central Asia to Shandong in a short period of time and was widely planted, which was a rapid spread through the Eurasian steppe channel. Second, the track of the eastward spread of wheat along the route of Silk Road can be confirmed by the wheat flour culture and customs retained by all ethnic groups in the Tibetan-Yi Corridor in China. Therefore, the ethnic channel provides a more concrete and diversified cognitive way for the study of wheat spread in China.
Gaofeng Zhang,Bingxing Chen,Gaocan Wu,Guoguang Xie,Hui Xie 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
In this study, we investigated the effects of composite nano-Cu/WS 2 lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool’s rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS 2 lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS 2 lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions.
Monitoring for Damage in Two-Dimensional Pre-Stress Scratching of SiC Ceramics
Gaofeng Zhang,Yijiang Zeng,Wenbo Zhang,Houming Zhou,Zhangya Wen,Yuan Yao 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.11
This paper reports an approach to use the acoustic emission (AE) technology for monitoring the surface/subsurface damage in twodimensional pre-stress scratching of SiC ceramics, in which the two-dimensional pre-stress is used to decrease the scratch-induced damage. Experiments in this study were conducted on a UMT-2 machine (CETR USA) utilizing a designed pre-stressing device under pressures of 0 MPa, 300 MPa and 500 MPa. The experimental results demonstrate that average frequency and magnitude of AE signals have a good correlation with the scratching tangential force and the scratch-induced surface /subsurface damage of materials. For a given normal load, the average frequency and magnitude of AE signals are observed to decrease with the increase in pre-stress, which indicates that surface/subsurface damage of SiC ceramics induced by two-dimensional pre-stress scratching is less than that induced by conventional scratching. The findings provide fundamental information for developing a practical on-line AE monitoring system that is effective in detecting surface/subsurface damage in scratching or grinding of ceramics. These results also demonstrate that two-dimensional pre-stress method contributes to decreasing the machining damage of brittle materials.
Single-Point Grinding of Alumina and Zirconia Ceramics Under Two-Dimensional Compressive Prestress
Gaofeng Zhang,Zhigang Wang,Wenxin Chen,Jingtao Li,Hao Sun,Kui Zhang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.1
In this study, single-point grinding experiments were performed on alumina and zirconia ceramics to investigate the grinding processes under two-dimensional compressive prestress (TCP). Grinding forces and grooves were measured under different values of TCP to evaluate the grinding defects. The material removal rate and actual grinding depth were exploited to investigate the grinding-induced damage and material
Gaofeng Han,Jing Li,Shuo Wang,Yan Liu,Xuedong Wang,Yanheng Zhou 대한치과교정학회 2019 대한치과교정학회지 Vol.49 No.2
Objective: This study was performed to evaluate the accuracy and reliability of a newly designed method to achieve mandibular dental model superimposition, using voxel-based cone-beam computed tomography (CBCT) registration. Methods: Fourteen dry cadaveric mandibles and six teeth extracted from patients with severe periodontitis were used to establish 14 orthodontic toothmovement models. The protocol consisted of two steps: in the first step, voxel-based CBCT mandible superimposition was performed; the reference comprised the external portion of the symphysis, extending to the first molar. The laser-scanned dental model image was then integrated with the CBCT image to achieve mandibular dental model superimposition. The entire process required approximately 10 minutes. Six landmarks were assigned to the teeth to measure tooth displacement, using tooth displacement on the superimposed laser-scanned mandibles as the reference standard. Accuracy was evaluated by comparing differences in tooth displacement based on the method and the reference standard. Two observers performed superimposition to evaluate reliability. Results: For three-dimensional tooth displacements, the differences between the method and the reference standard were not significant in the molar, premolar, or incisor groups (p > 0.05). The intraclass correlation coefficients for the inter- and intra-observer reliabilities of all measurements were > 0.92. Conclusions: Our method of mandibular dental model superimposition based on voxel registration is accurate, reliable, and can be performed within a reasonable period of time in vitro, demonstrating a potential for use in orthodontic patients.
Generative Human Action Tracking Based on Compressive Sensing
Gaofeng Li,Fei Wang,Wang Lei 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.7
Action tracking and recognition is a challenge due to human deformation and complex scene system. Tracking-by-detection methods are used to solve appearance changes problem caused by viewpoint, occlusion, scale or deformation. Here we propose a robust object tracking and generative action recognition method. Compressive sensing is improved to track object with superpixels, and the generative structural part model is designed to be adaptive to variation of deformable object. We evaluate the method on challenging sequences. Also, we make qualitative and quantitative discussion. The results indicate the method is robust, and it is adaptive to deformable object tracking and action recognition.
Study on the Agro-pastoral Ecotone in Northern China and the Spread of Wheat in China
Dai Gaofeng 아시아사회과학학회 2021 Jornal of Asia Social Science Vol.3 No.3
At present, the time series and spatial distribution of wheat spread in China are gradually clear according to archaeological excavations and literature studies, but there are problems that the eastern region is earlier than the western region in time and space, and the explanations of different disciplines conflict. The agro-pastoral ecotone in northern China is a transitional zone in arid and semi-arid climate. Historically, the climate and ecological changes in this region have led to the mixed evolution of people’s living patterns, forming an economic form of integration of agriculture and animal husbandry, thus becoming an important channel for wheat transmission in China. The agro-pastoral ecotone in northern China has the advantages of location, valley, livelihoods, ethnic groups and culture to promote the spread of wheat, which accelerates the spread of wheat to Shandong and Central Plains, and makes the spread of wheat in northern China show the phenomenon of time and space inversion.