oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 1 )

2019 ( 253 )

2018 ( 2222 )

2017 ( 2109 )

Custom range...

Search Results: 1 - 10 of 127048 matches for " Changhe Li "
All listed articles are free for downloading (OA Articles)
Page 1 /127048
Display every page Item
Applications of High-Efficiency Abrasive Process with CBN Grinding Wheel  [PDF]
Yali Hou, Changhe Li, Yan Zhou
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.23026
Abstract: High-efficiency abrasive process with CBN grinding wheel is one of the important techniques of advanced manufacture. Combined with raw and finishing machining, it can attain high material removal rate like turning, milling and planning. The difficult-to-grinding materials can also be ground by means of this method with high performance. In the present paper, development status and latest progresses on high-efficiency abrasive machining technologies with CBN grinding wheel relate to high speed and super-high speed grinding, quick point-grinding, high efficiency deep-cut grinding, creep feed deep grinding, heavy-duty snagging and abrasive belt grinding were summarized. The efficiency and parameters range of these abrasive machining processes were compared. The key technologies of high efficiency abrasive machining, including grinding wheel, spindle and bearing, grinder, coolant supplying, installation and orientation of wheel and workpiece and safety defended, as well as intelligent monitor and NC grinding were investigated. It is concluded that high efficiency abrasive machining is a promising technology in the future.
Bleaching effect and nonvolatile holographic storage in doubly doped LiNbO3:Fe:Cu crystals
Dean Liu,Liren Liu,Changhe Zhou,Liyong Ren,Guangao Li
Chinese Science Bulletin , 2002, DOI: 10.1007/BF03183311
Abstract: The bleaching effect, i.e. the crystal shows that decoloration after it is illuminated by ultraviolet light, has been observed in congruent LiNbO3:Fe:Cu crystals. Based on this bleaching effect, a new technique including the recording phase by two interfering red beams and fixing phase by both UV light and a coherent red beam has been experimentally investigated to realize nonvolatile holographic storage in LiNbO3:Fe:Cu. The results of proof-of-concept experiments confirm that bleaching effect becomes an alternative physical mechanism for nonvolatile holographic stor age with high recording sensitivity and weak light-induced scattering noise.
A Facile Procedure for the Conversion of Oximes to Ketones and Aldehydes with Potassium Dichromate in Dimethylformamide under Homogeneous Conditions
Li-Hong Huang,Ji-Dong Lou,Changhe Zhang,Fang Lin,Xiao-Nan Zou
Journal of Chemistry , 2012, DOI: 10.1155/2012/826527
Abstract: Oxidative cleavage of oximes to their parent corresponding carbonyl compounds using potassium dichromate-dimethylformamide system under homogeneous conditions in good yields is described. The main advantage of the present method is no need of preparation of hexavalent chromium-based reagents due to using a polar aprotic solvent.
Multi-scale Modeling of Land-cover Change and Ecosystem Service Values:A Case of the Yuzixi Catchment in Sichuan
土地覆被及生态服务价值变化的多时间尺度模拟——以四川省渔子溪流域为例

RAN Shenghong,LI Xiubin,LU Changhe,
冉圣宏
,李秀彬,吕昌河

地理学报 , 2006,
Abstract: The Yuzixi Catchment is located in the core of the Panda Natural Reserves in western Sichuan Province, with an area of 1742 km2. Due to influences of climate change and human activities, the land cover shows marked changes in the last decade. Using the land-cover data obtained from the remote sensing images of two years of 1986 and 1994, this paper developed two models based on the Markov Chain and Patch-dynamics approach, to simulate land-cover changes in the Yuzixi Catchment. Both models were verified using the land-cover data in 2002. Starting from the year 1994, the land-cover of the year 2002 was simulated in a time-step of 1 year and 8 years with these two models, respectively. Compared with the real land-cover data in 2002, it was found that the time scale had a marked effect on the simulation results, and the simulation error varied among different land use types. The simulation error of Patch-dynamics model of cultivated land (-8.2%/-5.6%), forest land (-0.5% /-0.4%), grassland (0.7%/0.4%) and residential area (-29.9% /-16.4% ) is bigger based on one-year scale than eight-year scale, and their changing trends are unstable due to the significant effect of anthropogenic factors. By contrast, the simulation error of bush land (-1.5%/-1.7%) and ice land (27.3%/41.9%) is smaller based on one-year scale than eight-year scale, and the changing trends are stable because they are mostly affected by natural factors. The research results also show that the simulation results of Markov Chain model are similar to that of Patch-dynamics model. However, the simulation results of Patch-dynamics model are more stable and reliable.
Environmental impact of the land use change in Yuzixi Catchment in the last 20 years
近20年渔子溪流域土地利用变化的环境影响

RAN Shenghong,LI Xiubin,Lv Changhe,
冉圣宏
,李秀彬,吕昌河

环境科学学报 , 2006,
Abstract: Non-pollution ecological impact is an important aspect of the environmental impact resulting from land use change, which can be assessed by the change in the value of ecosystem services and landscape pattern index. The ecosystem service function and landscape pattern index of Yuzixi catchment are quantitatively analyzed based on the remote sensing images in 1986, 1994 and 2002. The results show that the ecosystem service value in Yuzixi catchment increased 0.42% from 1986 to 2002. Thereinto, the relative change rate of provisioning services, regulating services, cultural services and supporting services are 1.15% , 0.36% , 0.16% and -0.94% , respectively. Their contributions to the overall change of these ecosystem services are 62.95% ,46.82% ,6.33% and - 16.1% , respectively. On the other hand, the landscape pattern has been changed because of the land use change. The patch density index decreased from 0. 0016 to 0. 0013 and the landscape fragment index increased from 0. 00307 to 0. 00474. The results of further analysis show that the changes of landscape pattern of different land use types are different since some scattered shrub land has been transferred to cultivated land or village construction and some perpetual ice land has been transferred to moderate grass land due to climate change.
A Facile Procedure for the Conversion of Oximes to Ketones and Aldehydes with Potassium Dichromate in Dimethylformamide under Homogeneous Conditions
Li-Hong Huang,Ji-Dong Lou,Changhe Zhang,Fang Lin,Xiao-Nan Zou
Journal of Chemistry , 2012, DOI: 10.1155/2012/826527
Abstract: Oxidative cleavage of oximes to their parent corresponding carbonyl compounds using potassium dichromate-dimethylformamide system under homogeneous conditions in good yields is described. The main advantage of the present method is no need of preparation of hexavalent chromium-based reagents due to using a polar aprotic solvent.
An Improved Admissible Heuristic for Learning Optimal Bayesian Networks
Changhe Yuan,Brandon Malone
Computer Science , 2012,
Abstract: Recently two search algorithms, A* and breadth-first branch and bound (BFBnB), were developed based on a simple admissible heuristic for learning Bayesian network structures that optimize a scoring function. The heuristic represents a relaxation of the learning problem such that each variable chooses optimal parents independently. As a result, the heuristic may contain many directed cycles and result in a loose bound. This paper introduces an improved admissible heuristic that tries to avoid directed cycles within small groups of variables. A sparse representation is also introduced to store only the unique optimal parent choices. Empirical results show that the new techniques significantly improved the efficiency and scalability of A* and BFBnB on most of datasets tested in this paper.
Evaluating Anytime Algorithms for Learning Optimal Bayesian Networks
Brandon Malone,Changhe Yuan
Computer Science , 2013,
Abstract: Exact algorithms for learning Bayesian networks guarantee to find provably optimal networks. However, they may fail in difficult learning tasks due to limited time or memory. In this research we adapt several anytime heuristic search-based algorithms to learn Bayesian networks. These algorithms find high-quality solutions quickly, and continually improve the incumbent solution or prove its optimality before resources are exhausted. Empirical results show that the anytime window A* algorithm usually finds higher-quality, often optimal, networks more quickly than other approaches. The results also show that, surprisingly, while generating networks with few parents per variable are structurally simpler, they are harder to learn than complex generating networks with more parents per variable.
Mortality among Methadone Maintenance Clients in China: A Six-Year Cohort Study
Xiaobin Cao, Zunyou Wu, Li Li, Lin Pang, Keming Rou, Changhe Wang, Wei Luo, Wenyuan Yin, Jianhua Li, Jennifer M. McGoogan, for the National Methadone Maintenance Treatment Program Working Group
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082476
Abstract: Objective To assess the overall mortality of methadone maintenance treatment (MMT) clients in China and its associated factors. Methods A total of 1,511 MMT clients, all of whom enrolled in China's first eight MMT clinics between March and December 2004, were included in this cohort study and followed for approximately six years, until June 2010. Mortality and its predictors were examined using Cox proportional hazards regression models. Results A total of 154 deaths were observed within 5,391 person-years (PY) of follow-up for an all-cause mortality rate of 28.6 per 1,000 PY. The leading causes of death were drug overdose (33.8%), HIV/AIDS-unrelated disease (21.4%), and HIV/AIDS (16.9%). The all-cause mortality rate of clients engaged in MMT for one year or less was roughly three times that of clients who stayed in MMT for four years or more (14.0 vs. 4.6, p<0.0001), HIV-positive subjects was nearly four times mortality rate than that of HIV-negative individuals (28.1 vs.6.8, p<0.0001). ART-naive HIV-positive subjects had approximately two times higher mortality rate than those receiving ART (31.2 vs. 17.3, <0.0001). After adjusting for confounding variables, we found that being male (HR = 1.63, CI: 1.03–2.57, p = 0.0355) and being HIV-positive (HR = 5.16, CI: 3.70–7.10, p<0.0001) were both associated with higher risk of death whereas increased durations of methadone treatment were associated with a lower risk of death (HR = 0.26, CI: 0.18–0.38, p<0.0001 for two to three years, HR = 0.08, CI: 0.05–0.14, p<0.0001 for four or more years). Conclusion Overall mortality was high among MMT clients in China. Specific interventions aimed at decreasing mortality among MMT clients are needed. Our study supports the need for keeping client at MMT longer and for expanding ART coverage and suggests the potential benefits of integrated MMT and ART services for drug users in China.
ASSESSMENT INDICATORS AND DIVISION OF HAZARD ENVIRONMENT IN THE REACHES OF YELLOW RIVER
黄河流域灾害环境的评估指标与区域划分

Lu Changhe,
吕昌河

地理科学进展 , 1998,
Abstract: With comprehensive analyses of the environment and natural hazards in the reaches of Yellow River, northern China, this paper determines indicators and criteria of assessing hazard environment, and formulates the division system and method of hazard environment. According to the indicators and hazard risk, 6 hazard zones, 14 classification regions and 31 sub-regions are identified in the reaches of Yellow River.
Page 1 /127048
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.