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Search Results: 1 - 10 of 269816 matches for " Liu D "
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Evaluation of High-Speed Track Quality Using Dynamic Simulation of Vehicle-Track Interaction  [PDF]
D. Liu, B. Lechner, S. Freudenstein
Journal of Transportation Technologies (JTTs) , 2016, DOI: 10.4236/jtts.2016.61002
Abstract: Track quality is a determinant factor for evaluating the overall performance of vehicle track interaction with respect to safety, ride quality and maintenance. Important parameters specifying the general quality of the track include track geometry (undamped) and track stiffness (damped), which can be evaluated by measurements taken along with track sections. A new co-simulation model based on Finite Element Method (FEM) and Multi Body Simulation (MBS) is built for the detailed description of track quality and its contribution to vehicle track interaction without simplifying the track structure as interconnected single elements. The simulation models and tools have been validated with the help of measured track geometry, track stiffness and dynamic wheel rail forces along the track sections of high speed lines. A comparative study between high speed lines using conventional ballasted track and ballastless track showed a significantly better quality in ballastless track sections. The dynamic forces which were determined by simulations and verified by measurements along the ballastless track section were comparatively less than the specified limits by German regulations for ballastless track design. Lower levels of dynamic forces can be utilized for optimization of track design and installation procedures with respect to lower initial costs.
Preventive effect of ordinary and hyperimmune bovine colostrums on mice diabetes induced by alloxan
D Pan, H Liu
African Journal of Biotechnology , 2008,
Abstract: In the present study, the anti-diabetic effect of ordinary and hyperimmune bovine colostrum were evaluated in diabetic mice induced by alloxan. The results indicated that blood glucose levels were significantly decreased after administration of colostrum for 30 d, and the glucose tolerance was strengthened in a dose-dependent manner. In addition, the hyperimmune colostrum was more efficient than ordinary colostrum in decreasing the blood glucose level and improving glucose tolerance in diabetic mice (P<0.05). Furthermore, total levels of serum cholesterol (TC) and triglycerides (TG) were significantly decreased, and serum high density lipoprotein cholesterol (HDL-c) was significantly increased in a dose-dependent manner compared with the control; the hyperimmune colostrum was also more efficient than ordinary colostrum in reducing the serum levels of TC and TG, and increasing the serum levels of HDL-c in diabetic mice (P<0.05). These results suggest that bovine colostrum could modify the diabetic phenotype of mice induced by alloxan.
Minocycline hydrochloride nanoliposomes inhibit the production of TNF-α in LPS-stimulated macrophages
Liu D, Yang PS
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S34036
Abstract: ocycline hydrochloride nanoliposomes inhibit the production of TNF-α in LPS-stimulated macrophages Original Research (1687) Total Article Views Authors: Liu D, Yang PS Published Date August 2012 Volume 2012:7 Pages 4769 - 4775 DOI: http://dx.doi.org/10.2147/IJN.S34036 Received: 20 May 2012 Accepted: 21 June 2012 Published: 31 August 2012 D Liu, P S Yang Shandong Provincial Key Laboratory of Oral Biomedicine, College of Stomatology, Shandong University, Shandong Province, People's Republic of China Background: As an adjunctive treatment of chronic periodontitis, it seems that the application of periocline or the other antimicrobials is effective against periodontopathogens. In this study, nanoliposomes were investigated as carriers of minocycline hydrochloride and the inhibition effects of minocycline hydrochloride nanoliposomes on the proliferation and lipopolysaccharide (LPS)-stimulated production of tumor necrosis factor-α (TNF-α) of macrophages were elucidated. Methods: After stimulation with 10 μg/mL LPS, murine macrophages (ANA-1) were treated with 10, 20, 40, 50 and 70 μg/mL 2% minocycline hydrochloride nanoliposomes, minocycline hydrochloride solution, and periocline for 6, 12, 24, 48 and 60 hours, respectively. A tetrazolium (MTT) assay was used to evaluate macrophages cell proliferation rate and the levels of TNF-α mRNA were measured by SYBR Green Real Time PCR. Results: Ten to 70 μg/mL 2% minocycline hydrochloride nanoliposomes, minocycline hydrochloride solution, and periocline showed dose- and time-dependent inhibition of ANA-1 proliferation. Minocycline hydrochloride nanoliposomes showed dose- and ratio-dependent inhibition of LPS-stimulated TNF-α secretion of ANA-1. The inhibition effect of 10 μg/mL minocycline hydrochloride nanoliposomes was significantly better than that of two positive control groups, and equated to that of 60 or 70 μg/mL periocline. The expression of TNF-α mRNA in experimental group continued to reduce linearly with time. Conclusion: All three preparations of minocycline hydrochloride showed dose- and time-dependent inhibition of proliferation of ANA-1. Minocycline hydrochloride nanoliposomes have stronger and longer inhibition effect on LPS-stimulated TNF-α secretion of macrophages cell than minocycline hydrochloride solution and periocline.
Analyse of maximum force of tip pinch, lateral pinch and palmer pinch in relation to maximum hangrip force
D Roman-Liu
Biology of Sport , 2003,
Abstract: The aim of the presented study was to develop a mathematical relationship expressing the pinch forces (tip pinch, lateral pinch and palmer pinch) in relation to handgrip force which will make it possible to determine maximum force for those three pinches in relation to upper limb location and gender. The predictive equation expressing maximum handgrip force in relation to upper limb location and gender has been developed on the basis of accessible data. By adopting the predictive equation of the maximum handgrip force, an analysis of pinch force values in relation to upper limb location was also performed. The developed relationship could be very useful in assessing maximum pinch forces for creating norms in sport, rehabilitation and occupational settings.
On selection of the optimal data time interval for real-time hydrological forecasting
J. Liu,D. Han
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-10829-2012
Abstract: With the advancement in modern telemetry and communication technologies, hydrological data can be collected with an increasingly higher sampling rate. An important issue deserving attention from the hydrological community is what suitable time interval of the model input data should be chosen in hydrological forecasting. Such a problem has long been recognised in the control engineering community but is a largely ignored topic in operational applications of hydrological forecasting. In this study, the intrinsic properties of rainfall-runoff data with different time intervals are first investigated from the perspectives of the sampling theorem and the information loss using the discrete wavelet decomposition tool. It is found that rainfall signals with very high sampling rates may not always improve the accuracy of rainfall-runoff modelling due to the catchment low-pass filtering effect. To further investigate the impact of data time interval in real-time forecasting, a real-time forecasting system is constructed by incorporating the Probability Distributed Model (PDM) with a real-time updating scheme, the autoregressive-moving average (ARMA) model. Case studies are then carried out on four UK catchments with different concentration times for real-time flow forecasting using data with different time intervals of 15 min, 30 min, 45 min, 60 min, 90 min and 120 min. A positive relation is found between the forecast lead time and the optimal choice of the data time interval, which is also highly dependent on the catchment concentration time. Finally, based on the conclusions from the case studies, a hypothetical pattern is proposed in three-dimensional coordinates to describe the general impact of the data time interval and to provide implications on the selection of the optimal time interval in real-time hydrological forecasting. Although nowadays most operational hydrological systems still have low data sampling rates (daily or hourly), the trend in the future is that higher sampling rates will become widespread and there is an urgent need for both academic and practising hydrologists to realise the significance of the data time interval issue. It is important that more case studies in different catchments with various hydrological forecasting models should be explored in the future to further verify and improve the proposed hypothetical pattern.
Growth rate and EBSD texture analysis of nitrogen doped diamond films
T. Liu,D. Raabe
Physics , 2008,
Abstract: Chemical-Vapor-Deposition (CVD) diamond films were prepared using a variation of nitrogen addition into the gas source admixture by a direct current CVD method. The influence of nitrogen addition on the crystallographic texture and grain shape evolution in heteroepitaxial polycrystalline diamond films was investigated using high-resolution electron backscattering diffraction (HR-EBSD) and X-ray diffraction (XRD). The analysis reveals that an addition of 1.5% N2 to the CH4 gas flow leads to a strong enhancement of a {110} fiber texture. The phenomenon is discussed in terms of a competitive growth selection mechanism.
The gauge technique for heavy quarks
R. Delbourgo,D. Liu
Physics , 1996, DOI: 10.1103/PhysRevD.56.27
Abstract: It is possible to determine a propapagator for heavy quarks to order 1/m in any covariant gauge, which applies universally to all quarks, by using the gauge technique. The leading behaviour is given by a _0F_2 function and the result is reliable in the infrared limit, accounting for soft-gluon corrections to the quark in internal loops.
Classical Trajectory Diagnosis of Finger-Like Pattern in the Correlated Electron Momentum Distribution for Helium Double Ionization
D. F. Ye,X. Liu,Jie liu
Physics , 2008, DOI: 10.1103/PhysRevLett.101.233003
Abstract: With a semiclassical quasistatic model we identify the distinct roles of nuclear Coulomb attraction, final state electron repulsion and electron-field interaction in forming the finger-like (or V-shaped) pattern in the correlated electron momentum distribution for Helium double ionization [Phys. Rev. Lett. \textbf{99}, 263002; \emph{ibid}, 263003 (2007)]. The underlying microscopic trajectory configurations responsible for asymmetric electron energy sharing after electron-electron collision have been uncovered and corresponding sub-cycle dynamics are analyzed. The correlation pattern is found to be sensitive to the transverse momentum of correlated electrons.
Soil organic carbon (SOC) accumulation in rice paddies under long-term agro-ecosystem experiments in southern China – VI. Changes in microbial community structure and respiratory activity
D. Liu,X. Liu,Y. Liu,L. Li
Biogeosciences Discussions , 2011, DOI: 10.5194/bgd-8-1529-2011
Abstract: Biological stabilization within accumulated soil organic carbon (SOC) has not been well understood, while its role in physical and chemical protection as well as of chemical recalcitrance had been addressed in Chinese rice paddies. In this study, topsoil samples were collected and respiratory activity measured in situ following rice harvest under different fertilization treatments of three long-term experimental sites across southern China in 2009. The SOC contents, microbial biomass carbon (SMBC) and nitrogen (SMBN) were analysed using chemical digestion and microbial community structure assessment via clony dilute plate counting methods. While SOC contents were consistently higher under compound chemical fertilization (Comp-Fert) or combined organic and inorganic fertilization (Comb-Fert) compared to N fertilization only (N-Fert), there was significantly higher fungal-bacterial ratio under Comb-Fert than under N-Fert and Comp-Fert. When subtracting the background effect under no fertilization treatment (Non-Fert), the increase both in SMBC and SMBN under fertilization treatment was found very significantly correlated to the increase in SOC over controls across the sites. Also, the ratio of culturable fungal to bacterial population numbers (F/B ratio) was well correlated with soil organic carbon contents in all samples across the sites studied. SOC accumulation favoured a build-up the microbial community with increasing fungal dominance in the rice paddies under fertilization treatments. While soil respiration rates were high under Comb-Fert as a result of enhanced microbial community build-up, the specific soil respiratory activity based on microbial biomass carbon was found in a significantly negatively correlation with the SOC contents for overall samples. Thus, a fungal-dominated microbial community seemed to slow SOC turnover, thereby favouring SOC accumulation under Comp-Fert or under Comb-Fert in the rice paddies. Therefore, the biological stabilization process is of importance in SOC sequestration in the rice paddies, operating with physical and chemical protection and chemical recalcitrance. However, sufficient understanding and prediction of SOM dynamics needs further quantitative characterization of the simultaneous operation of several mechanisms.
Response of mollusk assemblages from the Luochuan loess section to orbital forcing since the last 250 ka
Naiqin Wu,D. D. Rousseau,Xiuping Liu
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02886225
Abstract: This note presents a new result of terrestrial mollusk study from the Luochuan loess section since the last 250 ka. A total of 213 samples, taken at intervals of 10 cm in the S0-L3 portion, were analyzed for fossil mollusks. Generally, 150–600 individuals were counted in each sample. According to the distribution of mollusk fossil assemblages in the loess section, 11 mollusk fossil zones have been recognized, representing different climatic and ecological conditions. Three main ecological groups were identified according to the temperature and moisture requirements of each taxon. The cold-aridiphilous group shows maxima at about 240–220, 190–182, 150–140 and 74–66 ka BP. The thermo-humidiphilous set has high abundances for at least 6 times in the section at about 246–240, 220–216, 170–158, 92–86, 60–44 and 10 kaBP. Our results show that variations in mollusk ecological groups are related with changes in the Earth orbital parameters at the 41 and 20 ka frequencies. Maxima in thermo-humidiphilous taxa are in phase with accretion intervals of obliquity (41 ka period), reflecting the East Asian summer monsoon with 41 ka period in controlling variations in terrestrial mollusk ecological groups. In addition, maxima in thermohumidiphilous taxa appearing at about 246–240, 220–216, 60 and 10 kaBP, are consistent with procession (20 ka period) maxima, indicating that the procession period also plays an important role in adjusting the ecological pattern of mollusk groups.
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