scholarly journals Mixed Platoon Flow Dispersion Model Based on Speed-Truncated Gaussian Mixture Distribution

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Weitiao Wu ◽  
Wenzhou Jin ◽  
Luou Shen
Keyword(s):  
Model Comparison ◽  
Dispersion Model ◽  
Mixture Distribution ◽  
Flow Distribution ◽  
Gaussian Mixture ◽  
Parameters Estimation ◽  
The Road ◽  
Proposed Model ◽  
Truncated Gaussian ◽  
Gaussian Mixture Distribution

A mixed traffic flow feature is presented on urban arterials in China due to a large amount of buses. Based on field data, a macroscopic mixed platoon flow dispersion model (MPFDM) was proposed to simulate the platoon dispersion process along the road section between two adjacent intersections from the flow view. More close to field observation, truncated Gaussian mixture distribution was adopted as the speed density distribution for mixed platoon. Expectation maximum (EM) algorithm was used for parameters estimation. The relationship between the arriving flow distribution at downstream intersection and the departing flow distribution at upstream intersection was investigated using the proposed model. Comparison analysis using virtual flow data was performed between the Robertson model and the MPFDM. The results confirmed the validity of the proposed model.

Modelling the patient accrual with truncated Gaussian mixture distribution for the accurate estimation of sample size in survival trials

2020 ◽  
Vol 29 (10) ◽  
pp. 2972-2987
Author(s):  
Haixia Hu ◽  
Ling Wang ◽  
Chen Li ◽  
Wei Ge ◽  
Kejian Wu ◽  
...  
Keyword(s):  
Sample Size ◽  
Mixture Distribution ◽  
Gaussian Mixture ◽  
Accurate Estimation ◽  
Sample Size Estimation ◽  
Size Estimation ◽  
Accrual Rate ◽  
Truncated Gaussian ◽  
Patient Accrual ◽  
Gaussian Mixture Distribution

In survival trials with fixed trial length, the patient accrual rate has a significant impact on the sample size estimation or equivalently, on the power of trials. A larger sample size is required for the staggered patient entry. During enrollment, the patient accrual rate changes with the recruitment publicity effect, disease incidence and many other factors and fluctuations of the accrual rate occur frequently. However, the existing accrual models are either over-simplified for the constant rate assumption or complicated in calculation for the subdivision of the accrual period. A more flexible accrual model is required to represent the fluctuant patient accrual rate for accurate sample size estimation. In this paper, inspired by the flexibility of the Gaussian mixture distribution in approximating continuous densities, we propose the truncated Gaussian mixture distribution accrual model to represent different variations of accrual rate by different parameter configurations. The sample size calculation formula and the parameter setting of the proposed accrual model are discussed further.

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