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Search Results: 1 - 10 of 37001 matches for " Dongfeng Zhao "
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STUDY ON TWO POLLING SYSTEMS WITH EXHAUSTIVE SERVICE
两类周期查询式完全服务排队系统研究

Zhao Dongfeng,
赵东风

电子与信息学报 , 1999,
Abstract: This paper presents the analysis of a continuous-time model of the asymmetric polling system with exhaustive service. Compared with the discrete-time model of the polling system with exhaustive service(by Zhao Dongfeng, 1994), the results of two polling systems are given.
STUDY ON A NEW METHOD FOR CONTINUOUS-TIME SYSTEMS OF RANDOM ACCESS CHANNEL
一种新的时间连续型随机多址系统分析方法研究

Zhao Dongfeng,
赵东风

电子与信息学报 , 1999,
Abstract: In this paper, the continuous-time systems of the random access channel are analyzed by using the average cycle method. Analytic formulae for mean values of a successful period and a colliding period and an idle period are derived. Also, the upper bounds on the throughput of the system with capture effect and packet conflict resolution are provided. Finally, the simulation results of the random access channel are given.
A Routing Priority Scheduling Algorithm for MAC Layer in Wireless Sensor Networks
Liyong Bao,Dongfeng Zhao,Yifan Zhao
International Journal of Modern Education and Computer Science , 2011,
Abstract: Based on the ideas of conflict-free transmission, priority to guarantee transmission quality for communication between the different clusters , this article proposes a scheduling Algorithm fit for the MAC scheme of WSNs, which has made it possible for the polling service capable of differentiating services of the cluster head node of two priority levels. The high-priority service of the cluster head is responsible for routing between the different clusters, via exhaustive service policy, while the low-priority services of the cluster head node, for communication within the cluster through limited service policy with good fairness. The theoretical model of this scheme is established through Markov chain and probability generating function. Mathematical analysis is made on the mean queue length, the mean inquiry cyclic time and the mean delay time. It turns out that the findings from theoretical analysis correspond well with those from simulated experiments.
A Cluster-based priority Scheduling Algorithm for MAC Layer in Wireless Sensor Networks
Liyong Bao,Dongfeng Zhao,Yifan Zhao
Journal of Networks , 2011, DOI: 10.4304/jnw.6.10.1507-1513
Abstract: Based on the ideas of conflict-free transmission with high-efficiency, cluster-based networking model, and priority service, this article proposes a new scheduling algorithm of MAC protocol of WSNs, which has made possible the polling service capable of differentiating tasks of cluster nodes of two priority levels. The high-priority service of the cluster head is responsible for communication between the different clusters via exhaustive service policy, while the low-priority services of the cluster head node, for communication within the local cluster through limited service policy with good fairness. The theoretical model of this scheme is established through Markov chain, probability generating function, and Laplace-Stieltjes transformation. Mathematical analysis is made on the mean queue length, the mean inquiry cyclic time and the mean delay time. It is found that the findings from theoretical analysis correspond well with those from simulated experiments. The analyses demonstrate that this scheme enables an effective allocation of channel resources for different tasks, guarantee transmission quality of the communication between the different clusters, which further improve the cluster node's energy efficiency.
Control pattern of vocal center for vocalization in ruddy bunting (Emberiza rutila)
Jing Zhao,Jinchang Jiang,Dongfeng Li
Science China Life Sciences , 2003, DOI: 10.1360/02yc0079
Abstract: High vocal center (HVC) can produce single sound with one or two syllables by the single-type vocal control pattern in songbirds ruddy bunting (Emberiza rutila). It obviously shows left-side dominance in controlling double syllables, principal frequency (PF) and increasing sound intensity of the evoked calls. Meanwhile, the complex-type control pattern can produce complex calls with multisyllable, and also shows significant left-side dominance in controlling the number of syllables, tone changing and sound intensity. These indicate that left-side HVC controls higher frequency and complicated sentence structure. The basic vocal center, dorsomedial nucleus of the intercollicular complex (DM), controls the monosyllable sound in songbirds, and shows left-side dominance in controlling both the number of syllable and sound intensity. These results not only provide some direct evidence for left-side dominance in high vocal center, but also indicate that there is some internal connection between the high and basic vocal centers in songbirds.
Study on treatment of nondegration landfill leachate by electrolytic oxidation process
电解氧化处理难降解垃圾渗滤液研究

Li Weidong,Zhao Dongfeng,
李伟东
,赵东风

环境工程学报 , 2007,
Abstract: A continuous flow electrolytic through system was studied for the treatment of landfill leachates. The influences of electrode distance, current densities and chloride concentration on removal efficiencies were studied. The results showed that electrolytic oxidation process was effective on treatment of middle strength landfill leachates, when COD was less than 3000 rag/L, added chloride concentration was 6000 rag/L, the time was 60 minutes. The removal rates of COD and NH3-N can come up to 88.9% and 97.3% ,respectively,the energy consumed was 2.75 kWh/m^3. A valuable reference could be provided for a pilot scale research and industrial application.
The VEGF -634G>C promoter polymorphism is associated with risk of gastric cancer
Xiaoxiang Guan, Hui Zhao, Jiangong Niu, Dongfeng Tang, Jaffer A Ajani, Qingyi Wei
BMC Gastroenterology , 2009, DOI: 10.1186/1471-230x-9-77
Abstract: The risk associated with genotypes and haplotypes of four TGFB1 SNPs and four VEGF SNPs were determined by multivariate logistic regression analysis in 171 patients with gastric cancer and 353 cancer-free controls frequency-matched by age, sex and ethnicity.Compared with the VEGF-634GG genotype, the -634CG genotype and the combined -634CG+CC genotypes were associated with a significantly elevated risk of gastric cancer (adjusted OR = 1.88, 95% CI = 1.24-2.86 and adjusted OR = 1.56, 95% CI = 1.07-2.27, respectively). However, none of other TGFB1 and VEGF SNPs was associated with risk of gastric cancer.Our data suggested that the VEGF-634G>C SNP may be a marker for susceptibility to gastric cancer, and this finding needs to be validated in larger studies.Gastric cancer is one of the major causes of cancer-related deaths worldwide, although both incidence and mortality of gastric cancer have been declining in recent years [1]. In 2008, there were 21,500 new gastric cancer patients, and 10,880 patients died of this disease in the United States [2]. Epidemiological studies have identified many risk factors for gastric cancer, including older age, being a man, Helicobacter pylori (H. pylori) bacteria infection, diets high in smoked foods, salted fish and meats, and pickled vegetables, tobacco use and obesity [2]. Although about two-thirds of gastric cancer could be prevented by changing lifestyle and diet habits [3], the fact that some individuals develop gastric cancer while others do not when having similar exposures suggests that genetic factors may also play an important role in the etiology of gastric cancer.It has been reported that both TGF-β1 and VEGF played an important role in the oncogenesis of gastric cancer [4,5]. Both TGFB1 and VEGF genes are highly polymorphic, reportedly having 168 and 140 variants, respectively, but few are within the promoters or coding regions that may be potentially functional http://www.ncbi.nlm.nih.gov/SNP/ webcite. Of these variants
Polymorphisms of TGFB1 and VEGF genes and survival of patients with gastric cancer
Xiaoxiang Guan, Hui Zhao, Jiangong Niu, Dongfeng Tan, Jaffer A Ajani, Qingyi Wei
Journal of Experimental & Clinical Cancer Research , 2009, DOI: 10.1186/1756-9966-28-94
Abstract: We genotyped TGFB1 -509 C>T, +1869 T>C, and +915 G>C and VEGF -1498T>C, -634G>C, and +936C>T in 167 patients with gastric cancer. Using the Kaplan and Meier method, log-rank tests, and Cox proportional hazard models, we evaluated associations among TGFB1 and VEGF variants with overall, 1-year, and 2-year survival rates.Although there were no significant differences in overall survival rates among all polymorphisms tested, patients with TGFB1+915CG and CC genotypes had a poorer 2-year survival (adjusted hazard ratio (HR), 3.06; 95% confidence interval (CI), 1.09–8.62; P = 0.034) than patients with the GG genotype had. In addition, patients heterozygous for VEGF -634CG also had a poorer 1-year survival (adjusted HR, 2.08; 95% CI, 1.03–4.22; P = 0.042) than patients with the -634GG genotype.Our study suggested that TGFB1+915CG/CC and VEGF -634CG genotypes may be associated with short-term survival in gastric cancer patients. However, larger studies are needed to verify these findings.In gastric caner, patients with the same clinicopathologic characteristics and the same treatment regimens may have different clinical outcomes. Although stage is the best available clinical measure of tumor aggression and prognosis, there are clearly important differences even within the same tumor stage [1,2]. Therefore, it would be helpful to improve the prognostic accuracy by identifying readily accessible molecular markers that predict some of the variation in clinical outcomes. In recent decades, many studies have shown that genetic alterations play roles in the development and progression of gastric cancer [3]. Among these molecular markers, single nucleotide polymorphisms (SNPs) are the most commonly investigated genetic variation that may contribute to patients' clinical outcomes [4].Epidemiologic and clinical investigations have suggested that both TGF-β1 and VEGF may play an important role in the oncogenesis of the stomach [5,6]. For example, TGFB1 and VEGF variants are associat
Kinetics of C2 (a3Πu) radical reactions with NO, N2O, O2, H2 and NH3
Cunshun Huang,Zongxiao Li,Dongfeng Zhao,Yao Xin,Linsen Pei,Congxiang Chen,Yang Chen
Chinese Science Bulletin , 2004, DOI: 10.1007/BF02900960
Abstract: Based on the data analysis and theoretical calculation, we suggest that the C2(a3Πu) reactions with H2 and NH3 proceed via the hydrogen abstraction mechanism, barriers exist at the entrance channel of the reactions of C2(a3Πu) with H2 and NH3.
Control pattern of vocal center for vocalization in ruddy bunting (Emberiza rutila)
ZHAO Jing,JIANG Jinchang LI Dongfeng,
赵静
,蒋锦昌,李东风

中国科学C辑(英文版) , 2003,
Abstract: High vocal center (HVC) can produce single sound with one or two syllables by the sin-gle-type vocal control pattern in songbirds ruddy bunting (Emberiza rutila). It obviously shows left-side dominance in controlling double syllables, principal frequency (PF) and increasing sound intensity of the evoked calls. Meanwhile, the complex-type control pattern can produce complex calls with multisyllable, and also shows significant left-side dominance in controlling the number of syllables, tone changing and sound intensity. These indicate that left-side HVC controls higher frequency and complicated sentence structure. The basic vocal center, dorsomedial nucleus of the intercollicular complex (DM), controls the monosyllable sound in songbirds, and shows left-side dominance in controlling both the number of syllable and sound intensity. These results not only provide some direct evidence for left-side dominance in high vocal center, but also indicate that there is some internal connection between the high and basic vocal centers in songbirds.
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