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Search Results: 1 - 10 of 120007 matches for " Chenchen Wang "
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Effects of Engineering and Geology Factors on Oil-Water Flow Regularity in Sandstone Reservoir with Bottom Water Drive  [PDF]
Mingkun Zhai, Gaoming Yu, Yizhong Zhang, Chenchen Wang
Open Journal of Yangtze Oil and Gas (OJOGas) , 2018, DOI: 10.4236/ojogas.2018.34021
Abstract: The aim of this paper is to solve the problems such as complex morphology of water cone and ridge, as well as out-of-control flooding resulting from the abundant natural energy, formation heterogeneity and irregular inter-bed distribution. In this paper, the numerical simulation technique combined with the orthogonal experimental design method is applied to study the factors of engineering and geology that affect the oil-water flow regularity on Tahe sandstone reservoir with bottom water, such as reservoir permeability, liquid production rate, interlayered property and scale and location, liquid production rate, length of horizontal well etc. Results show that reservoir permeability, inter-layer and liquid production rate are key factors that influence the performance of coning and ridging water; the optimal lengths of horizontal wells change with different permeability formation. Besides, inter-layer physical properties also play an important role in the vertical well location. This study could provide theoretical and technical guidance for the early well spacing, the technical strategy of development as well as measures for water control and stability in sandstone reservoir with bottom water.
A Review of Air Pollution and Control in Hebei Province, China  [PDF]
Litao Wang, Jing Yang, Pu Zhang, Xiujuan Zhao, Zhe Wei, Fenfen Zhang, Jie Su, Chenchen Meng
Open Journal of Air Pollution (OJAP) , 2013, DOI: 10.4236/ojap.2013.23007
Abstract:

Hebei is one of the most air polluted provinces in China. According to the Ministry of Environmental Protection (MEP) for the severe fog-haze month of Jan. 2013, seven of the top ten most polluted cities in China are located in Hebei Province. In this study, the air pollution history and status of the Hebei Province are reviewed and discussed, using the governmental published Air Pollution Index (API), the academic observations by various scientific research groups and the long-term statistics of visibility and haze frequencies. It is found that within the Hebei Province, the air pollution in the southern cities is much more severe than the northern cities. Particulate matter (PM) is undoubtedly the major air pollutant, sulfur dioxide (SO2) and nitrogen oxides (NOX) pollutions are also unnegligible. Ozone (O3) pollution in larger cities, such as Shijiazhuang, is significant. Air pollution control history from 1998 is discussed as well. Although Hebei Province has made a great effort on air quality, the pollutant emissions, such as SO2 and fly ash, showed a notable increase in 2001 to 2006. However, after 2006 the emissions started to decrease due to the strict implementation of the national 11th Five Year Plan (FYP). In addition, regional jointly air pollution control and prevention strategies are expected in the future to substantially change the severe air pollution status in Hebei Province.

The Mechanism of Swainsonine Causing Early Pregnancy Abnormal Decidualization and Inducing Abortion by Changing Glycosylation Modification  [PDF]
Yi Wang, Xin Gao, Ming Peng, Yanfei You, Fangyun Shi, Yazhou Guo, Baoyu Zhao, Chenchen Wu
Advances in Reproductive Sciences (ARSci) , 2018, DOI: 10.4236/arsci.2018.63007
Abstract: Locoweed is a poisonous plant that severely harms the development of grass-land and animal husbandry throughout the world. Oxytropis and Astragalus are the Latin names for the poisonous plants commonly known as locoweed. The main toxic substance in these plants is swainsonine. It is a strong inhibitor of lysosomal α-mannosidase I and Golgi body α-mannosidase II, resulting in the accumulation of oligosaccharides and glycoproteins in lysosomes, interfering with the molecular and cellular recognition of glycans, and causing tissue-cell vacuolar degeneration. Livestock shows a series of clinical and pathological symptoms, mainly for the decline of reproductive performance. The effects in dams are abortion, weak fetus, and fetal malformations. The key step in maintaining pregnancy in dams is early endometrial decidualization, because reproductive hormones, decidual cell apoptosis, endoplasmic reticulum (ER) stress, and other immune factors are negatively affected by swainsonine. This article addresses the modifications that occur through glycan processing and glycosylation resulting in the change of post-translational modification of the protein and the activity of the glycoprotein, and then direct and indirect mechanisms of ER stress, apoptosis, reproductive hormones, immune factors, and cell cycle and other pathways. Our aim is to find new methods of prevention and treatment of swainsonine poisoning in grassland animals.
Effect of Plasma Treatment on Multi-Walled Carbon Nanotubes for the Detection of H2S and SO2
Xiaoxing Zhang,Bing Yang,Xiaojing Wang,Chenchen Luo
Sensors , 2012, DOI: 10.3390/s120709375
Abstract: H2S and SO2 are important characteristic gases of partial discharge (PD) generated by latent insulated defects in gas insulated switchgear (GIS). The detection of H2S and SO2 is of great significance in the diagnosis and assessment of the operating status of GIS. In this paper, we perform experiments on the gas sensitivity of unmodified multi-walled carbon nanotubes (MWNTs) and those modified by atmospheric pressure dielectric barrier discharge (DBD) air plasma at different times (30, 60 and 120 s) for H2S and SO2, respectively. The results show that the sensitivity and response time of modified MWNTs to H2S are both improved, whereas the opposite effects are observed for SO2. The modified MWNTs have almost zero sensitivity to SO2. Thus, the MWNTs modified by atmospheric pressure DBD air plasma present good selectivity to H2S, and have great potential in H2S detection.
The Effects of Mind-Body Therapies on the Immune System: Meta-Analysis
Nani Morgan, Michael R. Irwin, Mei Chung, Chenchen Wang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100903
Abstract: Importance Psychological and health-restorative benefits of mind-body therapies have been investigated, but their impact on the immune system remain less defined. Objective To conduct the first comprehensive review of available controlled trial evidence to evaluate the effects of mind-body therapies on the immune system, focusing on markers of inflammation and anti-viral related immune responses. Methods Data sources included MEDLINE, CINAHL, SPORTDiscus, and PsycINFO through September 1, 2013. Randomized controlled trials published in English evaluating at least four weeks of Tai Chi, Qi Gong, meditation, or Yoga that reported immune outcome measures were selected. Studies were synthesized separately by inflammatory (n = 18), anti-viral related immunity (n = 7), and enumerative (n = 14) outcomes measures. We performed random-effects meta-analyses using standardized mean difference when appropriate. Results Thirty-four studies published in 39 articles (total 2, 219 participants) met inclusion criteria. For inflammatory measures, after 7 to 16 weeks of mind-body intervention, there was a moderate effect on reduction of C-reactive protein (effect size [ES], 0.58; 95% confidence interval [CI], 0.04 to 1.12), a small but not statistically significant reduction of interleukin-6 (ES, 0.35; 95% CI, ?0.04 to 0.75), and negligible effect on tumor necrosis factor-α (ES, 0.21; 95% CI, ?0.15 to 0.58). For anti-viral related immune and enumerative measures, there were negligible effects on CD4 counts (ES, 0.15; 95% CI, ?0.04 to 0.34) and natural killer cell counts (ES, 0.12, 95% CI ?0.21 to 0.45). Some evidence indicated mind-body therapies increase immune responses to vaccination. Conclusions Mind-body therapies reduce markers of inflammation and influence virus-specific immune responses to vaccination despite minimal evidence suggesting effects on resting anti-viral or enumerative measures. These immunomodulatory effects, albeit incomplete, warrant further methodologically rigorous studies to determine the clinical implications of these findings for inflammatory and infectious disease outcomes.
Unraveling the luminescence signatures of chemical defects in polyethylene
Lihua Chen,Tran Doan Huan,Chenchen Wang,Rampi Ramprasad
Physics , 2015, DOI: 10.1063/1.4931986
Abstract: Chemical defects in polyethylene (PE) can deleteriously downgrade its electrical properties and performance. Although these defects usually leave spectroscopic signatures in terms of characteristic luminescence peaks, it is nontrivial to make unambiguous assignments of the peaks to specific defect types. In this work, we go beyond traditional density functional theory calculations to determine defect-derived emission and absorption energies in PE. In particular, we characterize PE defect levels in terms of thermodynamic and adiabatic charge transition levels that involve total energy calculations of neutral and charged defects. Calculations are performed at several levels of theory including those involving (semi)local and hybrid electron exchange-correlation functionals, and many-body perturbation theory. With these critical elements, the calculated defect transition levels are in excellent correspondence to observed luminescence spectra of PE, thus clarifying and confirming the origins of the observed peaks. Based on this work, a prescription with a reasonable computational expense is proposed to accurately predict and assign spectroscopic signatures of defects in other organic polymers as well.
$^3$H/$^3$He ratio as a probe of the nuclear symmetry energy at sub-saturation densities
Yongjia Wang,Chenchen Guo,Qingfeng Li,Hongfei Zhang
Physics , 2014, DOI: 10.1140/epja/i2015-15037-8
Abstract: Within the newly updated version of the Ultra-relativistic quantum molecular dynamics (UrQMD) model in which the Skyrme potential energy-density functional is introduced, the yield ratio between $^3$H and $^3$He clusters emitted from central $^{40}$Ca+$^{40}$Ca, $^{96}$Zr+$^{96}$Zr, $^{96}$Ru+$^{96}$Ru, and $^{197}$Au+$^{197}$Au collisions in the beam energy range from 0.12 to 1 GeV$/$nucleon is studied. The recent FOPI data for the $^3$H$/$$^3$He ratio are compared with UrQMD calculations using 13 Skyrme interactions (all exhibiting similar values of iso-scalar incompressibility but very different density dependences of the symmetry energy). It is found that the $^3$H$/$$^3$He ratio is sensitive to the nuclear symmetry energy at sub-saturation densities. Model calculations with moderately soft to linear symmetry energies are in agreement with the experimental FOPI data. This result is in line with both, the recent constraints on the low-density symmetry energy available in the literature and our previous results for the high-density symmetry energy obtained with the elliptic flow of free nucleons and hydrogen isotopes as a sensitive probe.
Effect of the spin-orbit interaction on flows in heavy-ion collisions at intermediate energies
Chenchen Guo,Yongjia Wang,Qingfeng Li,Feng-Shou Zhang
Physics , 2014, DOI: 10.1103/PhysRevC.90.034606
Abstract: The effect of the spin-orbit coupling in heavy ion collisions is investigated based on an updated version of the ultra-relativistic quantum molecular dynamics (UrQMD) model, in which the Skyrme potential energy density functional is employed. And in special, the spin-orbit coupling effects on the directed and elliptic flows of free nucleons emitted from $^{197}$Au+$^{197}$Au collisions as functions of both the beam energy and the impact parameter are studied. Our results show that the net contribution of the spin-orbit term to flows of nucleons is negligible, whereas a directed flow splitting between spin-up and spin-down nucleons is visible especially at large impact parameters and a peak of the splitting is found at the beam energy around 150 MeV$/$nucleon. We also found that the directed flow splitting between spin-up and spin-down neutrons is comparable with the neutron directed flow difference calculated by a soft and a stiff symmetry energy, indicating that the directed flow of neutrons cannot be used to pin down the stiffness of symmetry energy any more without considering the spin degree of freedom in models in case of spin polarization.
An improved approximation algorithm for k-median problem using a new factor-revealing LP
Chenchen Wu,Dachuan Xu,Donglei Du,Yishui Wang
Computer Science , 2014,
Abstract: The k-median problem is a well-known strongly NP-hard combinatorial optimization problem of both theoretical and practical significance. The previous best approximation ratio for this problem is 2.611+\epsilon (Bryka et al. 2014) based on an (1, 1.95238219) bi-factor approximation algorithm for the classical facility location problem (FLP). This work offers an improved algorithm with an approximation ratio 2.592 +\epsilon based on a new (1, 1.93910094) bi-factor approximation algorithm for the FLP.
When ICN Meets C-RAN for HetNets: An SDN Approach
Chenchen Yang,Zhiyong Chen,Bin Xia,Jiangzhou Wang
Computer Science , 2015,
Abstract: In this paper, we contribute to novelly proposing and elaborating the integration of the ICN, C-RAN and SDN for the HetNet to achieve win-win situation. The vision of the proposed system is demonstrated, followed by the advantages and challenges. We further present the hybrid system with a large-scale wireless heterogeneous campus network.
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