American Journal of Applied Mathematics

Volume 9, Issue 6, December 2021

  • Using Full Cohort Information to Improve the Estimation Efficiency of Marginal Hazard Model for Multivariate Failure Times in Case-Cohort Studies

    Hongtao Zhang, Haibo Zhou, David Couper, Jianwen Cai

    Issue: Volume 9, Issue 6, December 2021
    Pages: 192-210
    Received: 8 June 2021
    Accepted: 2 December 2021
    Published: 24 December 2021
    Abstract: The case-cohort design is widely used in large cohort studies when it is prohibitively costly to measure some exposures for all subjects in the full cohort, especially in studies where the disease rate is low. To investigate the effect of a risk factor on different diseases, multiple case-cohort studies using the same subcohort are usually conducte... Show More
  • Natural Gas Pipeline Transportation as the Thermodynamic Process

    Vladimir Alekber Suleymanov

    Issue: Volume 9, Issue 6, December 2021
    Pages: 211-215
    Received: 22 November 2021
    Accepted: 28 December 2021
    Published: 30 October 2021
    Abstract: A verification of commonly used approval in pipeline hydraulics is carried out that the work of friction forces performed at the movement of real gas on the gas pipeline completely turns into thermal energy. It is obvious that measurements of the actual temperature of the transported gas cannot confirm this hypothesis due to the inaccuracy of measu... Show More