168 research outputs found
Oncological and Functional Outcomes of Radical Cystectomy and Orthotopic Bladder Replacement in Women. Editorial comment
No full textDuring the last decades, orthotopic bladder substitution (OBS) after radical cystectomy for bladder cancer in women has been increasingly proposed. Meanwhile, strict patient selection criteria, improved surgical techniques, long-term follow-up in large patient cohorts, and validated evaluation have defined the role of OBS in men. Several issues must be clarified in women: oncological outcome, complication rates, functional results, quality of life, and sexual function. As a matter of fact, the results of OBS in women are substantially unchanged in the last decade as stated in this paper.
From the oncological standpoint, the patient outcome seems objectively satisfactory but selection criteria are different in the published series. Fortunately, the problem of urethra recurrence seems less relevant in properly selected patients.
However several issues are still a matter of debate. Functional results in terms of continence and hypercontinence are still unsatisfactory because the optimal way to reconstruct the pelvic anatomy is still undefined. Early and late complication rates are poorly evaluated. Little data are also available about the quality of life and sexual function.
Validated evaluation criteria in a large patient cohort are needed to objectively evaluate the results and to improve the substantially unchanged results reported in last decade. It's time to move forward!!
Non linear and linearized combination coefficients for modal pushover analysis
Full text linkcurrent design practice and seismic codes tend to assess seismic demand of buildings by Non linear Static Analysis (NSA), based on the evaluation of the pushover curve. Earlier non-linear static analysis procedure estimate the response peak value by evaluating the push-over curve adopting a distribution of invariant forces proportional to the fundamental vibration mode. In order to include the effect of higher modes several multi-modal push-over analysis procedures were proposed in literature. In In the most famous of these, namely Modal Pushover Analysis (MPA), nodal response peak values are obtained by combination of "modal" responses by the traditional SRSS or CQC methods: the use of the CQC rule is mandatory for irregular plane frames or spatial structures possessing modes with close natural frequencies. In order to take into account the actual characteristics of modal oscillators, the use of pertinent cross correlation coefficients defined for non-linear systems is required. In this paper the accuracy of correlation coefficients for linear systems in predicting the statistical correlation of hysteretic oscillator responses is investigated by a parametric analysis by Monte Carlo simulation. Furthermore, new correlation coefficients, determined through a pertinent statistical linearization are introduced, and the results provided by the classical and the proposed approach for two illustrative irregular plane and spatial frame are compared with non-linear time history analysis results, showing the effectiveness of the new procedure
Improving Urban Seismic Resilience through Vibrating Barriers
Full text linkEarthquakes are a well known natural hazard to urban environments. According to [2] under certain conditions, building vibrations significantly decrease when the mu l t iple interactions between the soil layers and all the buildings present in a city are considered in the analysis (site city interaction phenomenon). The present study focuses on the analysis of the multiple interactions between the soil and a city through 3D finite element models (FEM). The infl uence of the topography, buildings distributions, types of buildings (different resonant freque ncies) and spatial incoherency of the seismic motion will be also studied. Moreover, [1]proposed the idea of a novel device named vibrating barrier (ViBa) as a viable option to reduce the vibrations of adjacent buildings by exploiting the well known soil structure interaction phenomenon (SSI). The implementation of the ViBa device will be undertaken in a simplified FEM of an existing city as a way to enhance the resilience of the urban environment under seismic ground motion.
References [1] P. Cacciola and A. Tombari, 2015. Vibrating barrier: a novel device for the passive control of structures under ground motion. Proc Math Phys Eng Sci, 471, 20150075.[2] M. Kham, J. F, Semblat, P. Y. Bard, P. Dangla, 2006. Seismic site-city interaction: Main governing phenomena through simplified numerical models. Bulletin of the Seismological Society of America, 96, 1934-195
Combination of modal responses consistent with seismic input representation
No full textThe well-known modal superposition method for the evaluation of seismic response by the complete quadratic modal combination rule (CQC) is revisited. The most widely used version of the CQC rule utilizes correlation coefficients derived for white-noise excitation and neglects the influence of peak factor variation on the response. Here a simplified procedure for evaluation of correlation coefficients and peak factors consistent with the power spectral density of seismic excitation is proposed. The procedure is based on an approximate analytic expression for direct evaluation of the power spectral density of the excitation consistent with any prefixed response spectrum, and the evaluation of the consistent correlation coefficients and peak factors by using analytical expressions. The ranges of system dynamic parameters for which the correlation coefficients derived for white-noise excitation are not adequate are pointed out. Then the influence of the assumptions for CQC rule derivation on the evaluation of nodal response parameters is investigated, and the role played by the correlation coefficients and peak factors is pointed out
Stochastic sensitivity of steel frames with connection dampers by modal analysis
No full textA procedure for evaluation of dynamic response sensitivity of multistory steel frames with added viscoelastic beam to column connections by modal analysis is presented. The connection behavior is modeled by a Kelvin-Voigt element, consisting of a rotational spring and a dashpot connected in parallel. Consistent mass, stiffness and damping matrices of the multistory frame are utilized, leading to a structure modeling as a non-classically damped system. The procedure is based on the dynamic modification method, that allows to evaluate the response of non-classically damped structure by modal superposition, without transformation in the complex space. The differential equations governing the evolution of the derivatives of the responses (the so-called sensitivity equations) with respect to the stiffness and damping of the connections are derived in the modal subspace by a time domain approach. By means of an extensive employing of the Kronecker algebra the formulation is extended for evaluation of stochastic sensitivity of the dynamic response to a white noise excitation. The effectiveness of the proposed procedure in aiding the structural design is shown by evaluation of the response sensitivity of a eight-stow steel frame with added visco-elastic connections. The analysis allows to evaluate the parameter ranges for which the uncertainty in their evaluation results to a small risk level, due to a small sensitivity of the response
A modal approach for the evaluation of the response sensitivity of structural systems subjected to non-stationary random process
No full textA method for the evaluation of the response sensitivity of both classically and non-classically damped discrete linear structural systems under stochastic actions is presented. The proposed approach requires the following items: (a) a suitable modal expansion of the response; (b) the derivation in analytical form of the equations governing the evolution of the derivatives of the response (the so-called sensitivity equations) with respect to the parameters that define the structural model; (c) an extensive use of the Kronecker algebra for determining the analytical expressions of the sensitivity of the structural response statistics to non-stationary random input processes. Moreover, a step-by-step integration scheme able to solve the sensitivity equations is also studied. Handy expressions for the cross-correlations between the input process and the response sensitivities are also derived. A numerical application shows that the proposed approach is suitable to cope with practical problems of engineering interest
Combination coefficients for modal pushover analysis
No full textConventional non-linear static analysis estimates the response peak value by evaluating the pushover
curve adopting a distribution of invariant forces proportional to the fundamental vibration mode. In order
to include the effect of higher modes, multi-modal push-over analysis has been proposed in literature. Nodal response peak values are obtained by combination of “modal” responses usually by the traditional CQC method, requiring cross correlation coefficients defined for linear systems. In this paper, the accuracy of correlation coefficients for linear systems in predicting the statistical correlation of hysteretic oscillator responses is investigated by the Monte Carlo Simulation conducted on non-dimensional non-linear oscillators. Furthermore, new correlation coefficients determined through a pertinent statistical linearization are introduced, and the results provided by the classical and the proposed approach for two illustrative frames are compared with non-linear time history analysis, showing the effectiveness of the new procedure
Rilettura dell’iscrizione di Fl. Eutolmius Tatianus sul dipylon di Xanthus (378 d.C.)
No full textRe-examination of a Latin inscription found in Xanthus (Lycia) in 2021, which was engraved in 378 AD on the attic blocks of the two-arched arch in the heart of the city. It was dedicated by the comes sacrarum largitionum Fl. Eutolmius Tatianus in honour of the emperors Valens, Gratian and Valentinian II on the occasion of Valens’ Quindecennalia. The author proposes a new reading of the Latin text in line 3. The Latin inscription is exceptional because Tatianus seems to have personally, and exceptionally for a comes sacrarum largitionum, dedicated the monument in a city that could have been his homeland. His name was erased after his condemnation in 393 AD
A stochastic approach for generating spectrum compatible fully nonstationary earthquakes
Full text linkSimulation of artificial earthquakes in agreement with the provision of international seismic codes is addressed. Due to the importance of nonstationary frequency content on the seismic assessment of structures, in this paper a new method for generating spectrum compatible fully nonstationary earthquakes is proposed. The method assumes that the ground motion is modeled by the superposition of two contributions: the first one is a fully nonstationary counterpart modeled by a recorded earthquake; the second one is a corrective random process adjusting the recorded earthquake in order to make it spectrum compatible. Several examples show the accuracy of the proposed method
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