Earthquake induced floor accelerations on a high-rise building: Scale model tests on a shaking table

The paper discusses results of shaking table tests on an in-scale high-rise building model. The purpose was to calibrate a dynamic numerical model for multi-hazard analyses to investigate the effects of floor acceleration. Accelerations, because of vibration of non-structural elements, affect both the comfort and safety of people. The research investigates the acceleration effects of both seismic and wind forces on an aeroelastic in-scale model of a multi-story building. The paper discusses the first phase of experiments and gives results of floor accelerations induced by several different base seismic impulses. Structural analyses were first performed on the full-scale prototype to take soil-structure interaction into account. Subsequently the scale model was designed through aeroelastic scale laws. Shaking table experiments were then carried out under different base accelerations. The response of the model and, in particular, amplification of effects from base to top are discussed

Collective excitations of a trapped Bose-Einstein condensate in the presence of a 1D optical lattice

We study low-lying collective modes of a horizontally elongated 87Rb condensate produced in a 3D magnetic harmonic trap with the addition of a 1D periodic potential which is provided by a laser standing-wave along the horizontal axis. While the transverse breathing mode results unperturbed, quadrupole and dipole oscillations along the optical lattice are strongly modified. Precise measurements of the collective mode frequencies at different height of the optical barriers provide a stringent test of the theoretical model recently introduced [M.Kraemer et al. Phys. Rev. Lett. 88 180404 (2002)].Comment: 4 pages, 4 figure

The complex combination of COVID-19 and diabetes: pleiotropic changes in glucose metabolism

Purpose: Angiotensin converting enzyme 2 (ACE2) is the door for SARS-CoV-2, expressed in critical metabolic tissues. So, it is rational that the new virus causes pleiotropic alterations in glucose metabolism, resulting in the complication of pre-existing diabetes’s pathophysiology or creating new disease mechanisms. However, it seems that less attention has been paid to this issue. This review aimed to highlight the importance of long-term consequences and pleiotropic alterations in glucose metabolism following COVID-19 and emphasize the need for basic and clinical research in metabolism and endocrinology. Results: SARS-CoV-2 shifts cellular metabolism from oxidative phosphorylation to glycolysis, which leads to a decrease in ATP generation. Together with metabolic imbalance, the impaired immune system elevates the susceptibility of patients with diabetes to this deadly virus. SARS-CoV-2-induced metabolic alterations in immune cells can result in hyper inflammation and a cytokine storm. Metabolic dysfunction may affect therapies against SARS-CoV-2 infection. The effective control of metabolic complications could prove useful therapeutic targets for combating COVID-19. It is also necessary to understand the long-term consequences that will affect patients with diabetes who survived COVID-19. Conclusions: Since the pathophysiology of COVID-19 is still mostly unknown, identifying the metabolic mechanisms contributing to its progression is essential to provide specific ways to prevent and improve this dangerous virus’s detrimental effects. The findings show that the new virus may induce new-onset diabetes with uncertain metabolic and clinical features, supporting a potential role of COVID-19 in the development of diabetes

Laser induced fluorescence for axion dark matter detection: a feasibility study in YLiF4_4:Er3+^{3+}

We present a detection scheme to search for QCD axion dark matter, that is based on a direct interaction between axions and electrons explicitly predicted by DFSZ axion models. The local axion dark matter field shall drive transitions between Zeeman-split atomic levels separated by the axion rest mass energy $m_a c^2$. Axion-related excitations are then detected with an upconversion scheme involving a pump laser that converts the absorbed axion energy ($\sim$ hundreds of $\mu$eV) to visible or infrared photons, where single photon detection is an established technique. The proposed scheme involves rare-earth ions doped into solid-state crystalline materials, and the optical transitions take place between energy levels of $4f^N$ electron configuration. Beyond discussing theoretical aspects and requirements to achieve a cosmologically relevant sensitivity, especially in terms of spectroscopic material properties, we experimentally investigate backgrounds due to the pump laser at temperatures in the range $1.9-4.2$ K. Our results rule out excitation of the upper Zeeman component of the ground state by laser-related heating effects, and are of some help in optimizing activated material parameters to suppress the multiphonon-assisted Stokes fluorescence.Comment: 8 pages, 5 figure

High-power broadband laser source tunable from 3.0 um to 4.4 um based on a femtosecond Yb:fiber oscillator

We describe a tunable broadband mid-infrared laser source based on difference-frequency mixing of a 100 MHz femtosecond Yb:fiber laser oscillator and a Raman-shifted soliton generated with the same laser. The resulting light is tunable over 3.0 um to 4.4 um, with a FWHM bandwidth of 170 nm and maximum average output power up to 125 mW. The noise and coherence properties of this source are also investigated and described.Comment: To appear in Optics Letter

Dynamics of two colliding Bose-Einstein condensates in an elongated magneto-static trap

We study the dynamics of two interacting Bose-Einstein condensates, by numerically solving two coupled Gross-Pitaevskii equations at zero temperature. We consider the case of a sudden transfer of atoms between two trapped states with different magnetic moments: the two condensates are initially created with the same density profile, but are trapped into different magnetic potentials, whose minima are vertically displaced by a distance much larger than the initial size of both condensates. Then the two condensates begin to perform collective oscillations, undergoing a complex evolution, characterized by collisions between the two condensates. We investigate the effects of their mutual interaction on the center-of-mass oscillations and on the time evolution of the aspect ratios. Our theoretical analysis provides a useful insight into the recent experimental observations by Maddaloni et al., cond-mat/0003402.Comment: 8 pages, 7 figures, RevTe

Experimental characterization of tensile strength of steel and fibre rovings also under environmental conditioning

The efficiency of the strengthening techniques by externally applied materials can be improved enhancing the debonding strength of the reinforcement from the support by the use of connectors (anchor spikes) consisting of unidirectional bundles of fibres embedded in concrete or masonry by means of organic or inorganic matrices. The use of connectors is suggested in various codes and guidelines of strengthening techniques by composite materials and provisions for their application are given, but currently there are no details for the qualification of the material. In order to investigate anchor spikes made of glass, basalt, aramid, carbon, PBO and steel, a large experimental campaign was carried out at the Materials and Structures Laboratory of the University of Sannio. The tests allowed to evaluate the mechanical characteristics (tensile strength, modulus of elasticity, deformation at the maximum load) of the anchor spikes constituted by only dry fibres, not impregnated, also as a result of environmental conditioning such as freezing and thawing, controlled humidity, alkaline and saline environment

Exploitation of multi-objective optimization in retrofit analysis: a case study for the iron and steel production

Abstract Over the past few decades the issues related to the energy consumption and the climate change have been increased and they have achieved a significant position on the sustainability agenda of the steel industry. Steel production is among the largest energy-intensive industrial processes in the world, as well as one of the most important CO 2 emission sources. However, the major role of steel utilisation in the modern society is undeniable. The challenges of industrial energy systems aim at achieving CO 2 minimization, without neglecting energy efficiency as well as the development of effective models and strategies for process optimization. The application of Process Integration (PI) methods to the integrated steelmaking route, aims at achieving a reduction in the CO 2 emission by optimizing material and energy systems. The work presented in this paper is devoted to the development of a model for optimal exploitation of energy resources and by-products in integrated steelworks through application of multi-objective optimisation techniques. Cases of exploitation of the system within the management of the process gases are presented in a retrofit scenario and compared to the case of nominal operation

nonlinear model predictive control strategy for steam turbine rotor stress

Abstract The paper proposes a Nonlinear Model Predictive Control strategy for the control of steam turbines rotor thermal stresses, which exploits the approximation of the turbine rotor as an infinite cylinder subjected to external convection. The Nonlinear Model Predictive Control allows optimizing the control strategy in the long term, by significantly reducing the machine start-up time during the power up ramp. This study proposes two different control strategies: the former one is based on the control of the Heat Transfer Coefficient, correlated to the inlet valve stroke. The latter one is based on the control of Heat Transfer Coefficient and the boiler steam temperature reference. Both strategies achieve good results in shortening the start-up time. The overall approach is validated and currently under development on Programmable Logic Controller platforms to the aim of code optimization

Shake table tests for the seismic fragility evaluation of hospital rooms

© 2014 John Wiley & Sons, Ltd. Health care facilities may undergo severe and widespread damage that impairs the functionality of the system when it is stricken by an earthquake. Such detrimental response is emphasized either for the hospital buildings designed primarily for gravity loads or without employing base isolation/supplemental damping systems. Moreover, these buildings need to warrant operability especially in the aftermath of moderate-to-severe earthquake ground motions. The provisions implemented in the new seismic codes allow obtaining adequate seismic performance for the hospital structural components; nevertheless, they do not provide definite yet reliable rules to design and protect the building contents. To date, very few experimental tests have been carried out on hospital buildings equipped with nonstructural components as well as building contents. The present paper is aimed at establishing the limit states for a typical health care room and deriving empirical fragility curves by considering a systemic approach. Toward this aim, a full scale three-dimensional model of an examination (out patients consultation) room is constructed and tested dynamically by using the shaking table facility of the University of Naples, Italy. The sample room contains a number of typical medical components, which are either directly connected to the panel boards of the perimeter walls or behave as simple freestanding elements. The outcomes of the comprehensive shaking table tests carried out on the examination room have been utilized to derive fragility curves based on a systemic approach