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Search Results: 1 - 10 of 61117 matches for " YU Zhenxing "
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The Anti-allergic Activity of Polyphenol Extracted from Five Marine Algae The Anti-allergic Activity of Polyphenol Extracted from Five Marine Algae
CHEN Yu,LIN Hong,LI Zhenxing,MOU Quangui
- , 2015,
Abstract: Natural polyphenol has been widely believed to be effective in allergy remission. Currently, most of the natural polyphenol products come from terrestrial sources such as tea, grape seeds among others, and few polyphenols have been developed from algae for their anti-allergic activity. The aim of the study was to screen some commercial seaweed for natural extracts with anti-allergic activity. Five algae including Laminaria japonica, Porphyra sp., Spirulina platensis, Chlorella pyrenoidosa and Scytosiphon sp. were extracted with ethanol, and the extracts were evaluated for total polyphenol contents and anti-allergic activity with the hyaluronidase inhibition assay. Results showed that the total polyphenol contents in the ethanol extracts ranged from 1.67% to 8.47%, while the highest was found in the extract from Scytosiphon sp. Hyaluronidase inhibition assay showed that the extracts from Scytosiphon sp. had the lowest IC50, 0.67 mg m L-1, while Chlorella pyrenoidosa extract had the highest IC50, 15.07 mg m L-1. The anti-allergic activity of Scytosiphon sp. extract was even higher than the typical anti-allergic drug Disodium Cromoglycate(DSCG)(IC50 = 1.13 mg m L-1), and was similar with natural polyphenol from Epigallocatechin gallate(EGCG)(IC50 = 0.56 mg m L-1). These results indicated that the ethanol extract of Scytosiphon sp. contains a high concentration of polyphenol with high anti-allergic activity. Potentially Scytosiphon sp. can be developed to a natural anti-allergic compound for allergy remission
Structure properties for the superconductor MgCNi3 under high pressure with synchrotron radiation
Youlin Zhang,Fengying Li,Liangchen Chen,Jing Liu,Richeng Yu,Zhenxing Liu,Wen Yu,Changqing Jin
Chinese Science Bulletin , 2003, DOI: 10.1360/02ww0229
Abstract: In situ high pressure energy dispersive X-ray diffraction measurements on cubic-perovskite superconductor MgCNi3 under pressure up to 22 GPa have been performed by using diamond anvil cell with synchrotron radiation. We have investigated its crystal structure and compressibility. The results show that the structure of MgCNi3 is stable under pressure up to 22 GPa. According to Birch-Murnaghan state equation, when we assume B 0′ = 4, we get B0 = 267.8 ± 7.2 GPa.
Distributed Estimation in Wireless Sensor Networks with Heterogeneous Sensors
Zhenxing Luo
International Journal of Innovative Technology and Exploring Engineering , 2012,
Abstract: In this paper, a robust distributed estimation method in wireless sensor networks (WSNs) with heterogeneous sensors is presented. Particularly, a single parameter is estimated based on decisions from heterogeneous sensors, which have different signal gains. The sensor gains follow uniform distributions. Using the distributions of sensor gains, we calculated the probability density function of the signal received by sensors. Then, the overall likelihood function for a given decision vector is derived and a maximum likelihood estimation (MLE) method is used to estimate the unknown parameter. To evaluate estimation performance, the Cramer-Rao lower bound (CRLB) is also derived. Simulation results showed that if the range of sensor gains was narrow, the RMS errors were close to CRLB. If the range of sensor gains was wide, the RMS errors deviated from CRLB.
Robust Energy-based Target Localization in Wireless Sensor Networks in the Presence of Byzantine Attacks
Zhenxing Luo
International Journal of Innovative Technology and Exploring Engineering , 2012,
Abstract: This paper presents a robust energy-based target localization method in wireless sensor networks (WSNs) in the presence of Byzantine attacked sensors. Byzantine attacks will cause sensors to send false information to the fusion centre and disturb the target localization method. Therefore, a robust energy-based target localization method is needed to counter the Byzantine attacks and a method is presented in this paper. The method presented in this paper assumes that the fusion centre knows the exact information about the percentage of Byzantine sensors and the attack probability. If the fusion centre does not know the Byzantine attack information, a Byzantine sensor identification scheme can be used to identify Byzantine sensors. Results showed the robust energy-based target localization method could provide better performance results than the energy-based target localizatin method, which did not consider Byzantine attacked sensors. Moreover, simulation results showed that the Byzantine sensor identificaiton scheme could identify most Byzantine attacked sensors.
A New Direct Search Method for Distributed Estimation in Wireless Sensor Networks
Zhenxing Luo
International Journal of Innovative Technology and Exploring Engineering , 2012,
Abstract: Distributed estimation is a popular research topic inwireless sensor networks (WSNs). A maximum likelihoodestimation (MLE) method is widely used in WSNs for distributedestimation. However, the MLE method is a computationallyintensive method. To overcome this problem, in this paper, a newdirect search method will be presented. This method has muchlower computation complexity while can achieve estimationresults similar to the results given by the MLE method.
Overview of Applications of Wireless Sensor Networks
Zhenxing Luo
International Journal of Innovative Technology and Exploring Engineering , 2012,
Abstract: Wireless sensor networks (WSNs) have become a popular research topic recently due to their wide applications. Such wide applications also drive the development of WSNs because usually, the development of WSNs comes from challenges in real applications. Therefore, it is worthwhile to review some real applications to see how WSNs can be used and developed in the future to address more practical challenges.
Anti-attack and Channel Aware Target Localization in Wireless Sensor Networks Deployed in Hostile Environments
Zhenxing Luo
International Journal of Engineering and Advanced Technology , 2012,
Abstract: This paper discusses the attack and communicationchannel problems of the energy-based target localization methodin wireless sensor network. An anti-attack and channel aware(AACA) target localization method is presented to address theattack problem and the problem of communication channelerrors at the same time. Particularly, the AACA method proposedin this paper focuses on the Rayleigh fading channel withcoherent receiver. Moreover, the AACA method was comparedwith the weighted average (WA) method under attack andcommunication channnel errors. Results showed that the rootmean square (RMS) errors presented by the AACA method wereclose to the CRLB. Moreover, the WA method, although not ableto provide as good performance as the AACA method, could giveresults in much shorter time.
A Coding and Decoding Scheme for Energybased Target Localization in Wireless Sensor Networks
Zhenxing Luo
International Journal of Soft Computing & Engineering , 2012,
Abstract: A coding and decoding scheme for energy-basedtarget localization in wireless sensor networks (WSNs) ispresented in this paper. This scheme can improve targetlocalziation performance when WSNs are deployed in noisyenvironments. Simulation results showed that the energy-basedtarget localization method using this coding and decoding schemecould produce better localization performance than theenergy-based target localziation method which did not use thisscheme. Moreover, the root mean square (RMS) errors given bythe proposed method were close to the Cramer-Rao lower bound(CRLB).
Parameter Estimation in Wireless Sensor Networks with Normally Distributed Sensor Gains
Zhenxing Luo
International Journal of Soft Computing & Engineering , 2013,
Abstract: Wireless sensor networks (WSN) have attractedsignificant attention recently. The distributed estimation problemis an important research topic in WSNs. In the distributedestimation problem, the fusion center estimates an unknownparameter based on information gathered from sensors. Usually,it is assumed that sensors have identical gains. However, this maynot be true due to manufacture errors or environmental influence.In this paper, we assume sensor gains follow normal distributionand present a maximum likelihood estimation (MLE) approachfor distributed estimation in WSNs with normally distributedsensor gains. Moreover, the Cramer-Rao lower bound (CRLB)corresponding to this MLE approach is also derived. Simulationresults showed that the root square mean (RMS) estimation errorsgiven by this MLE approach were close to the CRLB if thevariance of the sensor gains is small. If the variance of the sensorgains was large, the RMS estimation errors were not close to theCRLB.
Parameter Estimation in Wireless Sensor Networks Based on Decisions Transmitted over Rayleigh Fading Channels
Zhenxing Luo
International Journal of Soft Computing & Engineering , 2013,
Abstract: In this paper, we present a distributed estimationmethod in wireless sensor networks (WSNs) based on decisionstransmitted over Rayleigh fading channels. The fusion centre canuses either coherent receiver or non-coherent receiver to acquiredecisions transmitted over Rayleigh fading channels. Theestimation method using coherent receiver and the estimationmethod using non-coherent receiver are presented and theCramer-Rao lower bounds (CRLBs) are derived. Simulationresults showed that in ideal situations, the RMS errors given bythe distributed estimation method were close to the CRLB.Moreover, simulation results highlighted the importance of thenumber of sensors, channel SNR, and accurate channel SNRinformation known to the fusion centre on estimationperformance.
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