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Search Results: 1 - 10 of 18609 matches for " Gao Qingwu "
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Uniform Asymptotics for the Finite-Time Ruin Probability of a Time-Dependent Risk Model with Pairwise Quasiasymptotically Independent Claims
Qingwu Gao
ISRN Probability and Statistics , 2012, DOI: 10.5402/2012/186348
Abstract:
Uniform Estimate of the Finite-Time Ruin Probability for All Times in a Generalized Compound Renewal Risk Model
Qingwu Gao,Na Jin,Juan Zheng
Advances in Decision Sciences , 2012, DOI: 10.1155/2012/936525
Abstract: We discuss the uniformly asymptotic estimate of the finite-time ruin probability for all times in a generalized compound renewal risk model, where the interarrival times of successive accidents and all the claim sizes caused by an accident are two sequences of random variables following a wide dependence structure. This wide dependence structure allows random variables to be either negatively dependent or positively dependent. 1. Introduction In this section, we will introduce a generalized compound renewal risk model, some common classes of heavy-tailed distributions, and some dependence structures of random variables (r.v.s), respectively. 1.1. Risk Model It is well known that the compound renewal risk model was first introduced by Tang et al. [1], and since then it has been extensively investigated by many researchers, for example, Ale?kevi?ien? et al. [2], Zhang et al. [3], Lin and Shen [4], Yang et al. [5], and the references therein. In the paper, we consider a generalized compound renewal risk model which satisfies the following assumptions. Assumption The interarrival times of successive accidents are nonnegative, identically distributed, but not necessarily independent r.v.s with finite mean . Assumption The claim sizes and their number caused by th accident are and , , respectively, where are nonnegative and identically distributed r.v.s with common distribution and finite mean , and are not necessarily independent r.v.s, but and are mutually independent for all , , while are independent, identically distributed (i.i.d.), and positive integer-valued r.v.s with common distribution and finite mean . Assumption The sequences , , and are mutually independent. Denote the arrival times of the th accident by , , which can form a nonstandard renewal counting process with mean function . Hence the total claim amount at time and the total claim amount up to time are, respectively, and then the insurer’s surplus process is given by where is the initial surplus and is the constant premium rate. The finite-time ruin probability within time is defined as Clearly, the ruin can only arise at the times , , then Let be a nonnegative r.v., the random time ruin probability is In order for the ultimate ruin not to be certain, we assume the safety loading condition holds, namely, In the generalized compound renewal risk model above, if all the sequences , , and are i.i.d. r.v.s, then the model is reduced to the standard compound renewal risk model introduced by Tang et al. [1], if , then the model is the renewal risk model, see Tang [6], Leipus and ?iaulys [7],
On the exponential inequality for acceptable random variables
Wang Yuebao,Li Yawei,Gao Qingwu
Journal of Inequalities and Applications , 2011,
Abstract: In this paper, we obtain some new exponential inequalities for partial sums and their finite maximum of acceptable random variables by the results of Sung et al. (J. Korean Stat. Soc., 40, 109-114, 2011) and in different ways from theirs. The inequalities we obtained improve the existing corresponding results and, in some sense, are optimal. In addition, we introduce some concepts and examples of widely acceptable random variables to extend our results mentioned above. Mathematics Subject Classification (2000) 60F15, 62G20
A New Multi-Method Combination Forecasting Model for ESDD Predicting  [PDF]
Haiyan SHUAI, Qingwu GONG
Energy and Power Engineering (EPE) , 2009, DOI: 10.4236/epe.2009.12015
Abstract: Equal Salt Deposit Density (ESDD) is a main factor to classify contamination severity and draw pollution distribution map. The precise ESDD forecasting plays an important role in the safety, economy and reliability of power system. To cope with the problems existing in the ESDD predicting by multivariate linear regression (MLR), back propagation (BP) neural network and least squares support vector machines (LSSVM), a nonlinear combination forecasting model based on wavelet neural network (WNN) for ESDD is proposed. The model is a WNN with three layers, whose input layer has three neurons and output layer has one neuron, namely, regarding the ESDD forecasting results of MLR, BP and LSSVM as the inputs of the model and the observed value as the output. In the interest of better reflection of the influence of each single forecasting model on ESDD and increase of the accuracy of ESDD prediction, Morlet wavelet is used to con-struct WNN, error backpropagation algorithm is adopted to train the network and genetic algorithm is used to determine the initials of the parameters. Simulation results show that the accuracy of the proposed combina-tion ESDD forecasting model is higher than that of any single model and that of traditional linear combina-tion forecasting (LCF) model. The model provides a new feasible way to increase the accuracy of pollution distribution map of power network.
Identification of Parasite-Host Habitats in Anxiang County, Hunan Province, China Based on Multi-Temporal China-Brazil Earth Resources Satellite (CBERS) Images
Zhijie Zhang, Robert Bergquist, Dongmei Chen, Baodong Yao, Zengliang Wang, Jie Gao, Qingwu Jiang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069447
Abstract: Remote sensing is a promising technique for monitoring the distribution and dynamics of various vector-borne diseases. In this study, we used the multi-temporal CBERS images, obtained free of charge, to predict the habitats of the snail Oncomelania hupensis, the sole intermediate host of schistosomiasis japonica, a snail-borne parasitic disease of considerable public health in China. Areas of suitable snail habitats were identified based on the normalized difference vegetation index (NDVI) and the normalized difference water index (NDWI), and the predictive model was tested against sites (snails present or absent) that were surveyed directly for O. hupensis. The model performed well (sensitivity and specificity were 63.64% and 78.09%, respectively), and with further development, we may provide an accurate, inexpensive tool for the broad-scale monitoring and control of schistosomiasis, and other similar vector-borne diseases.
Changing Patterns of Spatial Clustering of Schistosomiasis in Southwest China between 1999–2001 and 2007–2008: Assessing Progress toward Eradication after the World Bank Loan Project
Yi Hu,Chenglong Xiong,Zhijie Zhang,Can Luo,Ted Cohen,Jie Gao,Lijuan Zhang,Qingwu Jiang
International Journal of Environmental Research and Public Health , 2014, DOI: 10.3390/ijerph110100701
Abstract: We compared changes in the spatial clustering of schistosomiasis in Southwest China at the conclusion of and six years following the end of the World Bank Loan Project (WBLP), the control strategy of which was focused on the large-scale use of chemotherapy. Parasitological data were obtained through standardized surveys conducted in 1999–2001 and again in 2007–2008. Two alternate spatial cluster methods were used to identify spatial clusters of cases: Anselin’s Local Moran’s I test and Kulldorff’s spatial scan statistic. Substantial reductions in the burden of schistosomiasis were found after the end of the WBLP, but the spatial extent of schistosomiasis was not reduced across the study area. Spatial clusters continued to occur in three regions: Chengdu Plain, Yangtze River Valley, and Lancang River Valley during the two periods, and regularly involved five counties. These findings suggest that despite impressive reductions in burden, the hilly and mountainous regions of Southwest China remain at risk of schistosome re-emergence. Our results help to highlight specific locations where integrated control programs can focus to speed the elimination of schistosomiasis in China.
Shifts in the Spatiotemporal Dynamics of Schistosomiasis: A Case Study in Anhui Province, China
Yi Hu?,Rui Li?,Yue Chen?,Fenghua Gao,Qizhi Wang?,Shiqing Zhang?,Zhijie Zhang?,Qingwu Jiang
PLOS Neglected Tropical Diseases , 2015, DOI: 10.1371/journal.pntd.0003715
Abstract: Background The Chinese national surveillance system showed that the risk of Schistosoma japonicum infection fluctuated temporally. This dynamical change might indicate periodicity of the disease, and its understanding could significantly improve targeted interventions to reduce the burden of schistosomiasis. The goal of this study was to investigate how the schistosomiasis risk varied temporally and spatially in recent years. Methodology/Principal Findings Parasitological data were obtained through repeated cross-sectional surveys that were carried out during 1997-2010 in Anhui Province, East China. A multivariate autoregressive model, combined with principal oscillation pattern (POP) analysis, was used to evaluate the spatio-temporal variation of schistosomiasis risk. Results showed that the temporal changes of schistosomiasis risk in the study area could be decomposed into two sustained damped oscillatory modes with estimated period of approximately 2.5 years. The POPs associated with these oscillatory components showed that the pattern near the Yangtze River varied markedly and that the disease risk appeared to evolve in a Southwest/Northeast orientation. The POP coefficients showed decreasing tendency until 2001, then increasing during 2002-2005 and decaying afterwards. Conclusion The POP analysis characterized the variations of schistosomiasis risk over space and time and demonstrated that the disease mainly varied temporally along the Yangtze River. The schistosomiasis risk declined periodically with a temporal fluctuation. Whether it resulted from previous national control strategies on schistosomiasis needs further investigations.
Community Based Promotion on VCT Acceptance among Rural Migrants in Shanghai, China
Tiejun Zhang, Xiuhong Tian, Fuchang Ma, Ying Yang, Feng Yu, Yanping Zhao, Meiyang Gao, Yingying Ding, Qingwu Jiang, Na He
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0060106
Abstract: Objective Voluntary counseling and testing (VCT) plays an important integral role in response to the HIV/AIDS epidemic. However, VCT service has not been effectively utilized among rural migrants, a high risk group in China. In this study, we developed a community based intervention to examine if community mobilization with comprehensive VCT is more effective than current HIV preventions with routine VCT service in promoting VCT acceptability among rural migrants in Shanghai, China. Methods A comprehensive intervention with community mobilization and comprehensive VCT services including community-based VCT and mobile VCT was implemented during 2007–2009. Three communities in Minhang District of Shanghai were randomly selected and were designed to receive community mobilization and comprehensive VCT, traditional VCT and none intervention, respectively. After 24 months intervention, effects were evaluated by comparing outcome indicators between the baseline (2,690 participants) and follow-up surveys (1,850 participants). Findings A substantial increase in VCT acceptance was observed among community mobilization group (94.9% vs. 88.5%, P<0.001), whereas the reverse effect was seen in the traditional VCT group (86.1% vs. 94.6%, P<0.001) and control group (69.0% vs. 91.7%, P<0.001). Rural migrants from community mobilization group were more likely to accept VCT (OR = 2.91, 95% CI 1.69–4.97). Rural migrants from community mobilization group also showed significant increase in HIV/AIDS knowledge, positive attitude towards HIV positive individuals and condom use. Conclusion Community mobilization with comprehensive VCT has significant impact on promotion of VCT acceptance and utilization among rural migrants in Shanghai. These findings provide evidence to support community mobilization as a suitable strategy for VCT promotion among rural migrants in Shanghai, China.
Predicting protein folding pathways at the mesoscopic level based on native interactions between secondary structure elements
Qingwu Yang, Sing-Hoi Sze
BMC Bioinformatics , 2008, DOI: 10.1186/1471-2105-9-320
Abstract: By assuming that the native structure of a protein is known and representing each intermediate conformation as a collection of fully folded structures in which each of them contains a set of interacting secondary structure elements, we show that it is possible to significantly reduce the conformation space while still being able to predict the most energetically favorable folding pathway of large proteins with hundreds of residues at the mesoscopic level, including the pig muscle phosphoglycerate kinase with 416 residues. The model is detailed enough to distinguish between different folding pathways of structurally very similar proteins, including the streptococcal protein G and the peptostreptococcal protein L. The model is also able to recognize the differences between the folding pathways of protein G and its two structurally similar variants NuG1 and NuG2, which are even harder to distinguish. We show that this strategy can produce accurate predictions on many other proteins with experimentally determined intermediate folding states.Our technique is efficient enough to predict folding pathways for both large and small proteins at the mesoscopic level. Such a strategy is often the only feasible choice for large proteins. A software program implementing this strategy (SSFold) is available at http://faculty.cs.tamu.edu/shsze/ssfold webcite.As early studies revealed that an unfolded protein can fold spontaneously to a three-dimensional structure under suitable environmental conditions [1,2], traditional approaches to understanding protein folding have focused on the prediction of the native structure. As more studies showed the existence of intermediates and interaction among residues during the protein folding process [3,4], there is substantial interest to understand the time order of events during the formation of the tertiary structure. From the free energy point of view, each conformation of a protein is associated with a free energy and the protein folds from
Ti-Mo FERRITE MATRIX MICRO-ALLOY STEEL WITH NANOMETER-SIZED PRECIPITATES

DUAN Xiugang,CAI Qingwu,WU Huibin,

金属学报 , 2011,
Abstract:
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