Search results for "Optimal design"
showing 4 items of 114 documents
Efficient design and modeling strategies for follow-up studies with time-varying covariates
2015
Epidemiological studies can often be designed in several ways, some of which may be more optimal than others. Possible designs may differ in the required resources or the ability to provide reliable answers to the questions under study. In addition, once the data are collected, the selected modeling approach may affect how efficiently the data are utilized. The purpose of this dissertation is to investigate efficient designs and analysis meth ods in follow-up studies with longitudinal measurements. A key question is how to select optimally a subcohort for a new longitudinal covariate measurement if we cannot afford to measure the entire cohort. Another key question we consider is how to determine …
Dynamic shakedown design of structures under repeated seismic loads
2013
The paper is devoted to the formulation of an optimal design (minimum volume) problem of elastic perfectly plastic structures subjected to suitable combinations of static (fixed) and dynamic (seismic) loads. The structure is constrained to simultaneously respect two different safety criteria; actually, it must exhibit an elastic shakedown behaviour for the combination of loads characterizing the serviceability conditions and it must prevent the instantaneous collapse for the highest expected load condition (combination of loads characterized by the presence of fixed loads and maximum expected intensity of seismic action). The shakedown limit behaviour for the optimal structure will be impos…
Comparison between unrestricted dynamic shakedown design and a new probabilistic approach for structures under seismic loadings
2014
The paper concerns a study related to the comparison between two different approaches utilized for the formulation of an optimal shakedown design problem for elastic plastic frame structures subjected to a combination of fixed and seismic loading. The first formulation utilizes the unrestricted dynamic shakedown theory, while the second one is based on a new probabilistic approach. The comparison is effected in terms of mathematical formulations, in terms of adopted loading models and in terms of numerical results. The performed applications are related to plane steel frames.
Minor Losses and Best Manifold Position in the Optimal Design of Paired Sloped Drip Laterals
2018
Arranging paired laterals so that two distribution pipes extend in opposite directions from a common manifold contributes to providing more uniform pressure to all laterals in the system, increasing water use and energy efficiency of micro-irrigation. Towards this end, by neglecting emitters’ minor losses, analytical procedures to design paired drip laterals laid on uniform slopes were introduced. More recently, it was shown that for an optimal paired sloped lateral design the best position of the manifold (BMP) equals 24%. In this paper, first the mentioned analytical procedure is extended to the case in which minor losses are considered. Second, by neglecting minor losses, a comparison in…