A new generalized exponentiated Weibull model called Gumbel-exponentiated </span><span style="font-family:Verdana;">Weibull</span><span style="font-family:""> </span...A new generalized exponentiated Weibull model called Gumbel-exponentiated </span><span style="font-family:Verdana;">Weibull</span><span style="font-family:""> </span><span style="font-family:Verdana;">{Logistic} distribution is introduced and studied. The new distribution extends the exponentiated Weibull distribution with additional parameters and bimodal densities. Some new and earlier distributions formed the sub-models of the proposed distribution. The mathematical properties of the new distribution including expressions for the hazard function, survival function, moments, order statistics, mean deviation and absolute mean deviation from the mean, and entropy were derived. Monte Carlo simulation study was carried out to assess the finite sample behavior of the parameter estimates by maximum likelihood estimation approach. The superiority of the new generalized exponentiated Weibull distribution over some competing distributions was proved empirically using the fitted results from </span><span style="font-family:Verdana;">three</span><span style="font-family:Verdana;"> real life datasets.展开更多
The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim...The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus persica in open forests in Iran. To investigate the probability distribution of trees in natural stands, 642 trees were selected for measurement using a systematic random sampling method. Selected trees were measured and data were analyzed. Gamma, beta, normal,lognormal, exponential and Weibull probability distributions were fitted to the height distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov–Smirnov and Anderson–Darling tests. Beta, Weibull and Weibull probability distributions explained the distributions of tree height, DBH and crown area.展开更多
In this paper, the impact of atmospheric turbulence is investigated and analyzed for the Free Space Optical Mobile Ad Hoc Networks (FSO MANET) using the Network Simulator NS-3. The FSO channel random intensity fluctua...In this paper, the impact of atmospheric turbulence is investigated and analyzed for the Free Space Optical Mobile Ad Hoc Networks (FSO MANET) using the Network Simulator NS-3. The FSO channel random intensity fluctuations have been modeled using the Exponentiated Weibull (EW) distribution. Further, the FSO module has been implemented and integrated with NS3 using the FSO propagation model and the FSO error models. The computation of the key performance indicators (KPI) mainly the throughput and the packet delivery ratio (PDR) shows that the network density affects the network performance. Its effect was illustrated for the different turbulence regimes, strong and weak. It is found that the throughput and PDR values decrease as the number of mobile nodes becomes larger. For instance, at 150 kbps and in the presence of strong turbulence with 25, 50, and 75 nodes, the PDRs are 77%, 76%, and 73% respectively. Moreover, the throughput and PDR values in the strong turbulence regime are lower than those in the weak turbulence regime for the same date rate. The throughput in the strong turbulence regime with 75 mobile nodes at the data rate 150 kbps is 2100 kbps while it is 2300 kbps in the weak turbulence mode at the same rate.展开更多
With the support of the Fundamental Reliability Theoretical Research (FRTR) Foundation of the Quality Control Bureau of Ministry of Astronautics (MOA), PRC, 9 Chinese institutes and universities have worked for years ...With the support of the Fundamental Reliability Theoretical Research (FRTR) Foundation of the Quality Control Bureau of Ministry of Astronautics (MOA), PRC, 9 Chinese institutes and universities have worked for years on reliability statistics problems pending to be solved in space research and development. This paper gives a brief review of our main research results, including (1) Results on Normal Distributions; (2) Results on Weibull Distributions; (3) Results on the Synthesisof System Reliability-Theoretical Method; (4) Results on the Synthesis of System Reliability-Approximation Method: Binomial Distribution, Exponential Distribution, Weibull Distribution, Parallel System, General Cases; (5) Structual Reliability; (6) Zero-Failure Reliability Estimation; (7) Storage Life and Others. All these results can be acquired from the Quality Control Bureau of the Ministry of Aero-Space Industry (MAS).展开更多
文摘A new generalized exponentiated Weibull model called Gumbel-exponentiated </span><span style="font-family:Verdana;">Weibull</span><span style="font-family:""> </span><span style="font-family:Verdana;">{Logistic} distribution is introduced and studied. The new distribution extends the exponentiated Weibull distribution with additional parameters and bimodal densities. Some new and earlier distributions formed the sub-models of the proposed distribution. The mathematical properties of the new distribution including expressions for the hazard function, survival function, moments, order statistics, mean deviation and absolute mean deviation from the mean, and entropy were derived. Monte Carlo simulation study was carried out to assess the finite sample behavior of the parameter estimates by maximum likelihood estimation approach. The superiority of the new generalized exponentiated Weibull distribution over some competing distributions was proved empirically using the fitted results from </span><span style="font-family:Verdana;">three</span><span style="font-family:Verdana;"> real life datasets.
文摘The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus persica in open forests in Iran. To investigate the probability distribution of trees in natural stands, 642 trees were selected for measurement using a systematic random sampling method. Selected trees were measured and data were analyzed. Gamma, beta, normal,lognormal, exponential and Weibull probability distributions were fitted to the height distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov–Smirnov and Anderson–Darling tests. Beta, Weibull and Weibull probability distributions explained the distributions of tree height, DBH and crown area.
文摘In this paper, the impact of atmospheric turbulence is investigated and analyzed for the Free Space Optical Mobile Ad Hoc Networks (FSO MANET) using the Network Simulator NS-3. The FSO channel random intensity fluctuations have been modeled using the Exponentiated Weibull (EW) distribution. Further, the FSO module has been implemented and integrated with NS3 using the FSO propagation model and the FSO error models. The computation of the key performance indicators (KPI) mainly the throughput and the packet delivery ratio (PDR) shows that the network density affects the network performance. Its effect was illustrated for the different turbulence regimes, strong and weak. It is found that the throughput and PDR values decrease as the number of mobile nodes becomes larger. For instance, at 150 kbps and in the presence of strong turbulence with 25, 50, and 75 nodes, the PDRs are 77%, 76%, and 73% respectively. Moreover, the throughput and PDR values in the strong turbulence regime are lower than those in the weak turbulence regime for the same date rate. The throughput in the strong turbulence regime with 75 mobile nodes at the data rate 150 kbps is 2100 kbps while it is 2300 kbps in the weak turbulence mode at the same rate.
文摘With the support of the Fundamental Reliability Theoretical Research (FRTR) Foundation of the Quality Control Bureau of Ministry of Astronautics (MOA), PRC, 9 Chinese institutes and universities have worked for years on reliability statistics problems pending to be solved in space research and development. This paper gives a brief review of our main research results, including (1) Results on Normal Distributions; (2) Results on Weibull Distributions; (3) Results on the Synthesisof System Reliability-Theoretical Method; (4) Results on the Synthesis of System Reliability-Approximation Method: Binomial Distribution, Exponential Distribution, Weibull Distribution, Parallel System, General Cases; (5) Structual Reliability; (6) Zero-Failure Reliability Estimation; (7) Storage Life and Others. All these results can be acquired from the Quality Control Bureau of the Ministry of Aero-Space Industry (MAS).
