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Objective To compare the efficacy of 100 mg and 200 mg of mifepristone and 24-and 48-hour intervals to administration of 800mg vaginal misoprostol for termination of early pregnancy.Design Placebo-controlled, randomized, equivalence trial, stratified by centre.Setting 13 departments of obstetrics and gynecology in nine countries.Population 2181 women with 63 days or less gestation requesting medical abortion.Methods Two-sided 95% CI for the risk differences of failure to complete abortion were calculated and compared with 5% equivalence margin between two doses of mifepristone and two intervals to misoprostol administration. Proportions of women with adverse effects were compared between the regimens using standard testes for proportions.Outcome measures Rates of complete abortion without surgical intervention and adverse effects associated with the regimens.Results Efficacy outcome was analysed for 2126 women (97.5%) excluding 55 lost to follow up. Both mifepristone doses were found to be similar in efficacy. The rate of complete abortion was 92.0% for women assigned 100 mg of mifepristone and 93.2% for women assigned 200 mg of mifepristone (difference 1.2%, 95% CI: -1.0 to 3.5). Equivalence was also evident for the two intervals of administration: the rate of complete abortion was 93.5% for 24-hour interval and 91.7% for the 48-hour interval (difference -1.8%, 95% CI: -4.0 to 0.5). Interaction between doses and interval to misoprostol administration was not significant (P = 0.92). Adverse effects related to treatments did not differ between the groups.Conclusions Both the 100 and 200 mg doses of mifepristone and the 24-and 48-hour intervals have a similar efficacy to achieve complete abortion in early pregnancy when mifepristone is followed by 800 micrograms of vaginally administered misoprostol.

Active control problems of seismic-excited civil structures have attracted considerable attention in recent years. In this study, a design procedure of the hedge algebra-based fuzzy controller (HAFC) is investigated for a class of high-rise building systems with active tendons, which are subjected to seismic activity. In the HAFC, semantics of linguistic terms is obtained through semantically quantifying mappings (SQMs) without using any fuzzy set. Hence, the design of a HAFC leads to determining parameters of SQMs, which are fuzziness measures of primary terms and linguistic hedges occurring in a fuzzy model. To prove the validity of the HAFC in the aforementioned problem, an earthquake-excited 10-floor building with two actuators is numerically simulated.

A dual criterion of equivalent linearization method is suggested. The mean-square responses of Duffing, Van der Pol and Lutes-Sarkani oscillators subjected to random excitation are considered. The obtained results are compared with the numerical calculations of original systems and approximate solutions obtained by three different methods including the conventional linearization technique, energy method and regulation linearization method. The results show that in those nonlinear systems the accuracy of the mean-square response is significantly improved by the proposed criterion.

The vibration absorber has been used in many applications since invented. In the case of vibration control by the tuned mass damper (TMD), the selection of optimum absorber parameters is extremely important. This paper presents a closed-form expression for the optimum tuning ratio of a TMD attached to a damped primary system. The result is obtained by using equivalent linearization method. The values of the optimum tuning ratio derived from the expression proposed in this paper have been compared with those obtained numerically as well as the results obtained from other authors. These values are reliable even the mass ratio of TMD to the primary structure and the structural damping ratio are quite high. A simulation study has also been carried out to illustrate the obtained results.

Averaged values play major roles in the study of dynamic processes. The use of those values allows transforming varying processes to some constant characteristics that are much easier to be investigated. In order to extend the use of averaged values one may apply the dual approach which suggests a consideration of two different aspects of a problem in question. In this short communication the main idea of the dual conception is further extended to suggest a new form for weighting coefficient and then a new averaged value of functions. This new averaged value depends on the parameter \(s\) and contains the classical averaged value when \(s=0\). In the example of Duffing oscillator it is shown that the parameter \(s\) can be chosen as \(s=n/(2\pi)\) and for \(n=4\) one gets the solution that is much accurate than the conventional one obtained by the classical criterion of equivalent linearization.

There are two types of dynamic vibration absorbers (DVAs) for vibration reduction of a pendulum structure. The first one moving in the tangential direction of the pendulum's orbit can reduce all kinds of vibrations but the effectiveness is quite poor when the DVA locates near the centre of oscillation. Conversely, the second one moving in the normal direction of the pendulum's orbit can only reduce large vibration but has a good effect when the DVA's location is near the centre of oscillation. In this article, the authors propose the DVA, which can move in the normal and tangential directions at the same time. The proposed DVA can overcome the shortcoming of two DVAs moving in only one direction. Because the system's non-linearity is quite complex, a numerical method is used for obtaining the optimal parameters. Then, the authors introduce the convenient empirical formulas of optimal parameters based on the numerical results. The effect of the proposed DVA is demonstrated by the numerical calculations of free vibration of a ropeway gondola.

In this paper, the Equivalent Linearization Method (ELM) with a weighted averaging, which is proposed by Anh (Anh, 2015), is applied to analyze some vibrating systems with nonlinearities. The strongly nonlinear Duffing oscillator with third, fifth, and seventh powers of the amplitude, the other strongly nonlinear oscillators and the cubic Duffing with discontinuity are considered. The results obtained via this method are compared with the ones achieved by the Min-Max Approach (MMA), the Modified Lindstedt -Poincare Method (MLPM), the Parameter -Expansion Method (PEM), the Homotopy Perturbation Method (HPM) and 4 th order RungeKutta method. The obtained results demonstrate that this method is very convenient for solving nonlinear equations and also can be successfully exerted to a lot of practical engineering and physical problems.