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27. Almost-Sure Stochastic Stability of Viscoelastic Plates in Supersonic Flow

Author

Ariaratnam, S. T. and Abdelrahman, N. M.

Subjects
Aerospace engineering -- Methods, Viscoelasticity -- Measurement, Stochastic processes -- Methods, Aerodynamics, Supersonic -- Measurement, Aerospace and defense industries, Business
Abstract

The dynamic stability of a viscoelastic plate in a supersonic gas flow and subjected to a stochastically fluctuating axial thrust is performed within the concept of the Lyapunov exponent. The constitutive relation is modeled in an integral form by using the Boltzmann superposition principle. The piston theory as a quasi-first-order approximation is used to represent the aerodynamic loading on the plate. The stochastic averaging method is used and the Khasminskii's technique [Khasminskii, R. A., 'Necessary and Sufficient Conditions for the Asymptotic Stability of Linear Stochastic System,' Theory of Probability and Its Application, Vol. 12, No. 1, 1967, pp. 144-147 (English translation)] is employed to obtain the stability boundaries. The influence of the various plate and flow parameters and the random loading spectral densities on the stability are investigated.

Published
2001

32. Validation of Photogrammetric Monitoring for Trenchless Construction Applications

Author

Lueke, J., Su, P., Carey, Brad, Ariaratnam, S., Lueke, J., Su, P., Carey, Brad, and Ariaratnam, S.

Abstract

A primary concern of owners specifying trenchless installation and rehabilitation methods are surface movements during construction. Surface heave or settlement can occur as a result of contractor methodology, design, or geotechnical conditions. Performing quality assurance during and after construction provides owners with an understanding of what surface movements have occurred and if remedial action may be required. Traditional methods utilized to measure ground surface movements include surveying triangulation, geometric leveling, and global positioning system (GPS) surveying. This paper presents a procedure to utilize photogrammetry in the measuring of ground movements and examines its precision and accuracy in simulated field conditions. Utilizing consumer-grade digital single lens reflex (SLR) cameras, photogrammetry does not require highly trained personnel, takes less time, and costs less money than traditional methods. Accuracy is determined by comparing measurements taken with photogrammetry to those taken with traditional rod and level. The results are compiled and analyzed to determine the accuracy and precision of photogrammetry in measuring ground movements.

Published
2013

34. Depression and Associated Factors in Patients with Type 2 Diabetes Mellitus.

Author

Hashim, N. A., Ariaratnam, S., Salleh, M. R., Said, M. A., and Sulaiman, A. H.

Subjects
*TYPE 2 diabetes & psychology, *AGE distribution, *ANALYSIS of variance, *CHI-squared test, *MENTAL depression, *INTERVIEWING, *RESEARCH methodology, *MULTIVARIATE analysis, *PROBABILITY theory, *T-test (Statistics), *MATHEMATICAL variables, *LOGISTIC regression analysis, *SAMPLE size (Statistics), *INTER-observer reliability, *DISEASE prevalence, *CROSS-sectional method, *DATA analysis software, *DESCRIPTIVE statistics, *MANN Whitney U Test
Abstract

Objectives: To determine the prevalence of major depressive disorder and its association with socio-demographic and clinical factors in patients with type 2 diabetes mellitus. Methods: This was a cross-sectional study of patients with type 2 diabetes mellitus who attended the hospital-based primary care clinics at the University Malaya Medical Centre, Kuala Lumpur, Malaysia. The patients were interviewed using the Mini-International Neuropsychiatric Interview to diagnose depression based on the DSM-IV criteria. The socio-demographic and clinical data were obtained by interviewing the patients and subsequently verified against their respective case notes. Results: A total of 204 patients were recruited. The prevalence of major depressive disorder was 15.7%. Major depressive disorder was significantly associated with younger age of patients (mean ± standard deviation, 57.8± 15.1 years, p = 0.04), younger age at diagnosis of diabetes mellitus(46.2± 13.0years,p = 0.01), having secondary education (p = 0.02), and having a history of depression (p = 0.002). Multivariate analysis showed that current age (p = 0.04), duration of diabetes mellitus (p = 0.04), age at diagnosis of diabetes mellitus (p = 0.01), and secondary education (p = 0.01) were significant factors. Conclusions: The prevalence of major depressive disorder was high among patients with type 2 diabetes mellitus. Screening of patients with type 2 diabetes mellitus for depression should be performed periodically or routinely, especially in the primary care setting. [ABSTRACT FROM AUTHOR]

Published
2016

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