A min-max procedure for the shakedown analysis of skeletal structures

A solution procedure for elastic-plastic structures subjected to variable repeated loads is elaborated using a min-max formulation of the shakedown problem. This optimization procedure performed in a multi-dimensional space of parameters is transformed and further reduced to a solution of a set of algebraic equations and a one-dimensional minimization problem. To this purpose use is made of relationship between statically admissible residual stresses and plastic strains. The latter, treated in the analysis as free parameters, provide at the end of the optimization process some additional information on possible residual displacements prior to shakedown. Illustrative examples of space frames are presented to show the accuracy of the proposed procedure.     

Large displacements in-plane analysis of elastic-plastic frames

A large displacement theory for in-plane elastic plastic frames is formulated. The derivation is based on incremental variational principle using TLA formulation. A beam element with local-global DOF is used in the analysis. The method of solution of the FEM equations is related to computation in the load-configuration space R^N+1.

Results of two numerical examples are compared with classical solutions.     

Parametrical optimal design of funicular arches against buckling and vibration

The problem of determining the optimal piecewise constant area distribution along a funicular transverse vibrating arch under external load, so as to minimise the total volume, is investigated.     

Antihypertensive effect of amlodipine compared with nifedipine retard in patients with mild and moderate essential hypertension

OBJECTIVE: The present study was undertaken to evaluate the efficacy and safety of amlodipine for hypertension treatment in comparison with nifedipine retard. METHODS: We examined 31 patients with arterial blood pressure approximately 155-165 mmHg/100-105 mm Hg at the beginning of the trial. It was a randomized double-blind, parallel-group trial including two groups of patients. Patients of the first group were given active amlodipine and nifedipine retard placebo during 6 weeks, while the second group was given active nifedipine retard and amlodipine placebo. Statistical analysis was made using the paired Student's t-test, chi-square test and ANOVA test. RESULTS: At end point we observed significant decrease in arterial blood pressure after treatment of both drugs. The treatment with nifedipine retard increased the mean heart rate of patients. Amlodipine therapy in comparison to nifedipine retard did not change the heart rate in treated patients. Safety parameters: SGOT, SGTP, creatinine and others were in laboratory norms ranges. CONCLUSION: Amlodipine proved to be an effective, more safe and better-tolerated therapeutical alternative for hypertension management than nifedipine retard.