2,646 research outputs found

    Simulation of the 2009, Mw = 4 Tehran earthquake using a hybrid method of modal summation and finite difference

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    The Greater Tehran Area is the most important city of Iran and hosts about 20% of the country?s population. Despite the presence of major faults and the occurrence of historical earthquakes, the seismicity is relatively low at present. Thus, it is important to estimate the ground motion for preventive, reliable seismic hazard assessment. An earthquake with magnitude Mw = 4, which occurred close to Tehran, 17 October 2009, is the first local earthquake that has been recorded by the local strong ground motion network in Tehran. To simulate the ground motion caused by the earthquake a hybrid technique is used. It combines two methods: the analytical modal summation and the numerical finite difference, taking advantage of the merits of both. The modal summation is applied to simulate wave propagation from the source to the sedimentary basin and finite difference to propagate the incoming wavefield in the laterally heterogeneous part of the structural model that contains the sedimentary basin. Synthetic signals are simulated along two East?West and Southeast?Northwest profiles. Frequency, response spectra, and time domain, waveforms and peak values, parameters are computed synthetically and compared with observed records. Results show agreement between observed and simulated signals. The simulation shows local site amplification as high as 6 in the southern part of Tehran

    Offset-free economic mpc based on modifier adaptation: Investigation of several gradient-estimation techniques

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    Various offset-free economic model predictive control schemes that include a disturbance model and the modifier-adaptation principle have been proposed in recent years. These schemes are able to reach plant optimality asymptotically even in the presence of plant–model mismatch. All schemes are affected by a major issue that is common to all modifier-adaptation formulations, namely, plant optimality (note that convergence per se does not require perfect plant gradients) requires perfect knowledge of static plant gradients, which is a piece of information not known in most practical applications. To address this issue, we present two gradient-estimation techniques, one based on Broyden’s update and the other one on linear regression. We apply these techniques for the estimation of either the plant gradients or the modifiers directly. The resulting economic MPC schemes are tested in a simulation and compared on two benchmark examples of different complexity with respect to both convergence speed and robustness to measurement noise

    Evaluation of Linear and Nonlinear Site Effects for the MW 6.3, 2009 L’Aquila Earthquake

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    An effective strategy for the seismic risk mitigation needs the use of advanced seismological methodologies for a realistic estimate of the seismic hazard and, consequently, to reduce earthquake damage through a preventive evaluation of vulnerability and actions for structure safety. Prediction of earthquakes and their related effects (expressed in terms of ground shaking) can be performed either by a probabilistic approach or by using modelling tools based, on one hand, on the theoretical knowledge of the physics of the seismic source and of wave propagation and, on the other hand, on the rich database of geological, tectonic, historical information already available. Strong earthquakes are very rare phenomena and it is therefore statistically very difficult to assemble a representative database of recorded strong motion signals that could be analyzed to define ground motion parameters suitable for seismic hazard estimations. That is, the probabilistic estimation of the seismic hazard is a very gross approximation, and often a severe underestimation, of reality. A realistic and reliable estimate of the expected ground motion can be performed by using the Neo-Deterministic Seismic Hazard Analysis (NDSHA), an innovative modelling technique that takes into account source, propagation and local site effects (for a recent review see Panza et al., 2011). This is done using basic principles of physics about wave generation and propagation in complex media, and does not require to resort to convolutive approaches, that have been proven to be quite unreliable, mainly when dealing with complex geological structures, the most interesting from the practical point of view

    High-intensity interval training: optimizing oxygen consumption and time to exhaustion taking advantage of the exponential reconstitution behaviour of D’

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    Purpose: Accumulating the time near maximum aerobic power (V ˙ O 2max) is considered to be the most effective way to improve aerobic capacity. The aims of this study were: (1) to verify whether postponing the first recovery interval improves time to exhaustion during a high-intensity interval training (HIIT) test, and (2) to verify whether a HIIT protocol with decreasing interval duration (HIDIT) is more effective in accumulating time near V ˙ O 2max compared with two classical protocols with short intervals (SIHIIT) and long intervals (LIHIIT). Methods: Nine active males (35 ± 11 years, V ˙ O 2max 52 ± 5 mL·min−1·kg−1) performed a graded exercise test on an athletic track. Critical velocity and D’ were estimated from three to five high-intensity trials to exhaustion. Then, the subjects performed three trials with a single recovery interval after 30 s (Rec30s), after 3 min (Rec3min) and after exhaustion (RecTlim) to verify whether postponing the first recovery interval enhances the time to exhaustion. Finally, the subjects performed the three HIIT protocols mentioned above. Results: The time to exhaustion was significantly greater in RecTlim (464 ± 67 s) than in Rec3min (388 ± 48 s) (p 0.0001). Additionally, it was significantly greater in Rec3min than in Rec30s (p = 0.0247). Furthermore, the time accumulated near V ˙ O 2max was significantly longer in HIDIT (998 ± 129 s) than in SIHIIT (678 ± 116 s) (p = 0.003) and LIHIIT (673 ± 115 s) (p < 0.031). Conclusions: During the trials, postponing the first recovery interval was effective in improving the time to exhaustion. Moreover, HIDIT was effective in prolonging the time near V ˙ O 2max

    Fetal Kidney Programming By Severe Food Restriction: Effects On Structure, Hormonal Receptor Expression And Urinary Sodium Excretion In Rats

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Introduction: The present study investigates, in 23-day-old and adult male rats, the effect of severe food restriction in utero on blood pressure (BP), and its association with nephron structure and function changes, angiotensin II (AT1R/AT2R), glucocorticoid (GR) and mineralocorticoid (MR) receptor expression. Materials and methods: The daily food supply to pregnant rats was measured and one group (n=15) received normal quantity of food (NF) while the other received 50% of that (FR50%) (n=15). Kidneys were processed to AT1R, AT2R, MR, and GR immunolocalization and for western blotting analysis. The renal function was estimated by creatinine and lithium clearances in 12-week-old offspring. Results: By stereological analyses, FR50% offspring present a reduction of nephron numbers (35%) with unchanged renal volume. Expression of AT1R and AT2R was significantly decreased in FR50% while the expression of GR and MR increased in FR50%. We also verified a pronounced decrease in urinary sodium excretion accompanied by increased BP in 12-week-old FR50% offspring. Conclusion: The current data suggest that changes in renal function are conducive to excess sodium tubule reabsorption, and this might potentiate the programming of adult hypertension. It is plausible to arise in the current study an association between decreasing natriuresis, reciprocal changes in renal AngII and steroid receptors with the hypertension development found in FR50% compared with age-matched NF offspring.1613346Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2005/54362-4, 2009/02719-7, 2010/52696-0

    Characterization of the Elastic Displacement Demand: Case Study - Sofia City

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    The results of the study on the seismic site response of a part of the metropolitan Sofia are discussed. The neo-deterministic seismic hazard assessment procedure has been used to compute realistic synthetic waveforms considering four earthquake scenarios, with magnitudes M=3.7, M=6.3 and M = 7.0. Source and site specific ground motion time histories are computed along three selected cross sections, making use of the hybrid approach, combining the modal summation technique and the finite differences scheme. Displacement and acceleration response spectra are considered. These results are validated against the design elastic displacement response spectra and displacement demand, recommended in Eurocode 8. The elastic response design spectrum from the standard pseudo-acceleration, versus natural period, Tn, format is converted to the Sa Sd format. The elastic displacement response spectra and displacement demand are discussed with respect to the earthquake magnitude, the seismic source-to-site distance, seismic source mechanism and the local geological site conditions

    The Sky Arrow ERA, an innovative airborne platform to monitor mass, momentum and energy exchange of ecosystems

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    Substantial worldwide efforts are underway aimed at identifying the spatial and temporal distribution of the global sources and sinks of atmospheric carbon dioxide (CO2). The sink/source strength of vegetated surfaces at ground sites can now be estimated with reasonable accuracy and micrometeorological techniques are now well established, while difficulties exist in up scaling these figures to the regional and global scales. Airborne measurement of mass, momentum, and energy fluxes for boundary layer research has been available for decades requiring the use of large aircraft to carry instruments and dedicated support facilities. The advent of compact, lowpower instruments and high speed, high-capacity digital data acquisition systems has recently allowed small research aircraft to perform such measurements with high accuracy. This paper first describes the Sky Arrow ERA (Environmental Research Aircraft), a small research aircraft that has been recently developed in Italy, in the frame of an international scientific collaboration. This aircraft can be operated to measure fluxes of mass, momentum and energy while flying at low altitude and reduced ground speed. The fluxes are computed with the airborne eddy correlation technique. The basic theory at the basis of the flux measurement technique is also described in the paper, and two application examples are discussed to illustrate the quality and the accuracy of the measurements that can be made using this research platform. Potential applications of those data to parametrize land surface schemes, validate simulation models and provide extensive and reliable ground truthing for satellite remote sensing applications are highlighted

    Diltiazem downregulates IL-12 production by human dendritic cells

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    It is well known that IL-12 plays a central role in the initiation and control of allogeneic immune response. It promotes the proliferation of lymphocytes and NK cells, cytotoxic activity of NK cells, and CTL. It was recently shown that IL-12 is involved in the regulation of T helper Th1-Th2 responses by exerting stimulatory effects on Th1 and inhibitory effects on Th2. This regulatory role is believed to result from the ability of IL-12 to induce IFN-γ production in activated T cells and NK cells.[1 and 2] Th1 cytokines (IL-2 and IFN-γ) promote both CTL and delayed-type hypersensitivity (DTH) responses, which are considered the principal effector mechanisms of allograft rejection. Diltiazem, a calcium channel blocker used in organ transplantation, is often included in clinical protocols in association with cyclosporin A and corticosteroids.[3] It was used initially because of its antinephrotoxic and antihypertensive effects, so that the undesirable side effects induced by immunosuppressive therapy could be reduced. We previously studied the effect of diltiazem on human mixed lymphocyte reactions (MLR) and on isolated human monocytes, showing the capacity of this drug to affect proinflammatory cytokine production.[4 and 5] Since dendritic cells (DCs) are the most effective antigen-presenting cells (APCs) to prime naive T cells, we were interested in determining the influence of diltiazem on human DCs. Human DCs generated from peripheral blood monocytes in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) have been characterised as immature DCs. To become fully potent APCs, DCs must undergo maturation induced either by a proinflammatory signal such as lipopolysaccharide (LPS) or by interaction with CD40L expressed on activated T lymphocytes. [6] The ability of mature DCs to act as potent APCs is due to their high expression of MHC and costimulatory molecules and also to their production of cytokines, especially IL-12. Therefore, we determined the effect of diltiazem on cytokine production by human DCs with a particular interest in IL-1β, IL-6, TNF-α, and IL-12 production
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