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Search Results: 1 - 10 of 104247 matches for " ZHANG Haigang "
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Knowledge-based genetic algorithms data fusion and its application in mine mixed-gas detection
Haigang Li,Deming Wang,Yong Zhang
Journal of Software , 2012, DOI: 10.4304/jsw.7.2.303-307
Abstract: In Considering that the high concentration of mine gas and hydrogen will disturb the output of electrochemical carbon monoxide sensor, this paper integrates gas sensor array with data fusion Algorithm. The output signals of three sensors are trained by BP neural network to get the mathematical model of information fusion for the analysis of mixed gas of methane, hydrogen and carbon monoxide. The experiments show that the information fusion could correct the crossed sensitivity error, and improve the accuracy of carbon monoxide, therefore achieve quantitative analysis mixed gas of coal mine.
Monge-Ampere equation on exterior domains
Jiguang Bao,Haigang Li,Lei Zhang
Mathematics , 2013,
Abstract: We consider the Monge-Amp\`ere equation $\det(D^2u)=f$ where $f$ is a positive function in $\mathbb R^n$ and $f=1+O(|x|^{-\beta})$ for some $\beta>2$ at infinity. If the equation is globally defined on $\mathbb R^n$ we classify the asymptotic behavior of solutions at infinity. If the equation is defined outside a convex bounded set we solve the corresponding exterior Dirichlet problem. Finally we prove for $n\ge 3$ the existence of global solutions with prescribed asymptotic behavior at infinity. The assumption $\beta>2$ is sharp for all the results in this article.
Global solutions and exterior Dirichlet problem for Monge-Ampere equation in $\mathbb R^2$
Jiguang Bao,Haigang Li,Lei Zhang
Mathematics , 2015,
Abstract: Monge-Amp\`ere equation $\det(D^2u)=f$ in two dimensional spaces is different in nature from their counterparts in higher dimensional spaces. In this article we employ new ideas to establish two main results for the Monge-Amp\`ere equation defined either globally in $\mathbb R^2$ or outside a convex set. First we prove the existence of a global solution that satisfies a prescribed asymptotic behavior at infinity, if $f$ is asymptotically close to a positive constant. Then we solve the exterior Dirichlet problem if data are given on the boundary of a convex set and at infinity.
Long-range correlations in remotely sensed chlorophyll in the South China Sea
Haigang Zhan,Ping Shi,Qinwen Mao,Tonghui Zhang
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-9045-7
Abstract: A 8-year time series of 8-day Seaviewing Wide Field-of-view Sensor (SeaWiFS) data, which spans from Oct 1997 to Oct 2005, was used to study the temporal correlations and scaling behaviour of ocean chlorophyll fluctuations in the South China Sea (SCS) by means of detrended fluctuation analysis (DFA). Long-range correlations in chlorophyll fluctuations were detected in almost all the SCS. The scaling exponents vary over a wide range from 0.5 to 1.14, with an average value of 0.79. High values are found in the upwelling regions, such as the northwest of Luzon and the north of Sunda Shelf. Low values occur in the southwest of Luzon, the east of Hainan Island and a majority of the southern SCS. This spatial pattern is considerably different from that of the scaling exponents of the sea surface temperature (SST) time series. It is also demonstrated that SST exhibits more persistence than chlorophyll in almost all the SCS.
Jam Eyes: A Traffic Jam Awareness and Observation System Using Mobile Phones
Xing Zhang,Haigang Gong,Zongyi Xu,Jinchuan Tang
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/921208
Abstract:
A Study on Event-Driven TDMA Protocol for Wireless Sensor Networks
Gong Haigang,Liu Ming,Chen Guihai,Zhang Xue
EURASIP Journal on Wireless Communications and Networking , 2010,
Abstract: MAC protocol controls the activity of wireless radio of sensor nodes directly so that it is the major consumer of sensor energy and the energy efficiency of MAC protocol makes a strong impact on the network performance. TDMA-based MAC protocol is inherently collision-free and can rule out idle listening since nodes know when to transmit. However, conventional TDMA protocol is not suitable for event-driven applications. In this paper, we present ED-TDMA, an event-driven TDMA protocol for wireless sensor networks. Then we conduct extensive simulations to compare it with other MAC protocols such as BMA, S-MAC, and LMAC. Simulation results show that ED-TDMA performs better for event-driven application in wireless sensor networks with high-density deployment and under low traffic.
A Study on Event-Driven TDMA Protocol for Wireless Sensor Networks
Haigang Gong,Ming Liu,Guihai Chen,Xue Zhang
EURASIP Journal on Wireless Communications and Networking , 2010, DOI: 10.1155/2010/169132
Abstract:
Jam Eyes: A Traffic Jam Awareness and Observation System Using Mobile Phones
Xing Zhang,Haigang Gong,Zongyi Xu,Jinchuan Tang,Bang Liu
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/921208
Abstract: Traffic jam is a very common and very annoying thing in urban traffic. The most annoying part in traffic jams is not that you have to wait for a long time but that you do not even know how long you have to wait and what causes the traffic jam. However, the pain of being trapped in traffic jams seems to be neglected by existing research works; they put their focuses on either mathematical modeling or optimal routing for those not trapped in traffic jams. In this paper, we propose a traffic jam awareness and observation system using mobile phones. It can tell a driver how many vehicles ahead are trapped in traffic jam and how much time the driver would probably wait. Moreover, it can provide real-time video streams from the head vehicles of the traffic queue so that the driver can see what causes the traffic jam and the progress of handling the traffic jam. The system is environment independen; it can even work when the traffic jam happens in a tunnel. Experiments show that our system can find the head vehicles of the traffic queue and give the queue length accurately, and the video streams coming from the head vehicles reflect the actual situation of the traffic jam basically. 1. Introduction Traffic jam is already a daily routine of modern urban traffic. The sources of traffic jam can be categorized into three ways: a temporary obstruction, a permanent capacity constraint in the network itself, and a stochastic fluctuation in the demand within a particular sector of the network [1]. Obviously, the second way is the fundamental reason why traffic jam happens so frequently. Researchers have been trying their best to reduce the frequency of traffic jam; however, their works are basically a kind of optimization, as long as the network capacity is far from handling the actual increasing traffic flows, traffic jams will be inevitable and be getting worse. Now that traffic jam is inevitable, we should at least pay some attention to relieving sufferings of people from trapping in traffic jams. Almost everyone living in the city has experienced traffic jam; the most annoying thing in traffic jam is not that people have to wait for a long time but that people even do not know how long they have to wait. When people are trapped in a traffic jam, unless they are the head of traffic queue, they hardly know what causes the traffic jam, how long is the traffic queue, and how is the progress of handling the traffic jam. In psychology, lines of evidence shows that people have strong fear of unknown [2]. Although the mentioned information cannot handle the traffic jam,
Lipopolysaccharide Exposure during Pregnancy Leads to Aortic Dysfunction in Offspring Rats
Shanyu Zhao, Haigang Zhang, Dayan Cao, Ya Liu, Xiaohui Li
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102273
Abstract: Background Prenatal exposure to Lipopolysaccharide (LPS) produces hypertension in adult offspring rats. The present study was to explore the effects of prenatal inflammation on morphological and functional changes in the aorta from offspring rats and to further assess its susceptibility to cardiovascular diseases. Methods and Results Pregnant rats were treated intraperitoneally on gestation Days 8, 10 and 12 with saline, LPS (0.79 mg/kg), or pyrrolidine dithiocarbamate (PDTC, 100 mg/kg)+LPS, respectively. Aortic ring reactivity and histopathological alteration were analyzed in offspring at the age of 12 weeks. The detections of connexin (Cx) 37, Cx40, Cx43, and Cx45, including immunofluorescent patterns, protein levels and mRNA expression in the aorta, were performed as well. Furthermore, the expressions of Nuclear factor (NF)-κB (p65), IκBα, phospho-IκBα and IκBβ were determined. The results showed that prenatal LPS exposure leads to morphological abnormalities and impaired aortic reactivity in offspring. Prenatal LPS exposure also decreased the protein and mRNA expression of Cx37 in the aorta from offspring rats. NF-κB and phospho-IκBα levels were both increased, IκBα level, however, was decreased in the aorta of offspring from the maternal LPS exposure compared to the controls. Simultaneously, PDTC treatment markedly reversed the action of LPS. Conclusions Decreased expression of Cx37 contributed to the aortic dysfunction of prenatal LPS exposure offspring, which should be associated with NF-κB activation.
Duration Dependence in Bull and Bear Stock Markets  [PDF]
Haigang Zhou, Steven E. Rigdon
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.23031
Abstract: Testing duration in stock markets concerns the ability to predict the turning points of bull and bear cycles. The Weibull renewal process has been used in previous studies to analyze duration dependence in economic and financial cycles. A goodness-of-fit test, however, shows that this model does not fit data from U.S. stock market cycles. As a solution, this study fits the modulated power law process that relies on less restrictive assumptions. Moreover, it measures both the long term properties of bull and bear markets, such as the tendency of the cycles to become shorter (or longer), as well as the short term effects, such as duration dependence. The results give evidence of negative duration dependence in all samples of bull markets and evidence of positive duration dependence in complete, peacetime and post WWII samples of bear markets. There is no evidence of any structural change in duration dependence after WWII in either bull or bear markets. The results show that bull and bear markets tend to get progressively shorter, but for bull markets this trend has accelerated since WWII whereas for bear markets this trend has decelerated since WWII. Goodness-of-fit tests suggest that the modulated power is a suitable model for U.S. stock market cycles.
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