The Use of a Pendulum Dynamic Mass Absorber to Protect a Trilithic Symmetric System from the Overturning

The trilith consists of two vertical elements (columns) supporting a horizontal element (lintel). The understanding of the dynamic behaviour of triliths is an important step towards their preservation and starts with the knowledge of the dynamics of rigid blocks. A passive method based on a dynamic mass absorber is used to protect a trilith from overturning. The protection system is modelled as a pendulum, hinged on the lintel, with the mass lumped at the end. The equations of rocking motion, uplift and the impact conditions are obtained for the coupled system trilith-mass absorber. An extensive parametric analysis is performed with the aim to compare the behaviour of the system with and without the pendulum, under impulsive one-sine (or one-cosine) base excitations. In order to point out the effectiveness of the protection system, overturning spectra, providing the amplitude of the excitation versus its frequency, are obtained. The pendulum mass absorber results effective in avoiding overturning in specific ranges of the frequency of the excitation. However, outside these ranges the mass absorber never compromises the safety of the trilith

Structural disconnection as a general technique to improve the dynamic and seismic response of structures: a basic model

Abstract The Base Isolation ( BI ) and the Tuned Mass Damper ( TMD ) represent two different techniques to reduce vibrations in building structures. Both these techniques may be considered as descending from an appropriate "disconnection" carried out on a given structure, whose global mass is subdivided in two parts, with a substantial difference in stiffness. The present work aims to study the characteristics of the disconnection and its effectiveness in reducing the dynamic response of a building structure subject to a base excitation. A simple 2- DOF "archetype" model has been developed to describe structural systems where a disconnection has been performed. This model has a constant total mass while stiffness and mass ratios, related to the two degrees of freedom, are taken as main variable parameters. Two distinct reference schemes ( BI -scheme and TMD -scheme) have been adopted in order to identify the specific part of the structure (respectively upper or lower) whose dynamic response should take advantage from the disconnection. A measurement of such advantage has been then proposed by means of different "gain parameters", related to each scheme. The behavior of the gain parameters has been depicted in various maps, each one defined for different base accelerations

probability models to assess the seismic safety of rigid block like structures and the effectiveness of two safety devices

Abstract When subject to earthquakes, some objects and structures, such as statues, obelisks, storage systems, and transformers, show a dynamic behavior that can be modeled considering the object/structure as a rigid block. Several papers have studied the dynamic behavior of both stand-alone rigid blocks and systems where rigid blocks have been paired with safety devices to prevent or delay the overturning of the blocks. Although the safety devices have generally been proven to be effective, their effectiveness changes substantially varying the parameters that characterize the system and the seismic input. This paper compares the seismic responses of stand along rigid blocks with those of blocks coupled with two candidate safety devices: an isolating base and a pendulum mass damper. To account for the relevant uncertainties, probabilistic seismic demand models are developed using a Bayesian approach. The probabilistic models are then used along with the overturning capacities of the blocks to construct fragility curves that give a prediction of the probability of overturning occurrence as a function of some characteristics of the blocks, of the safety devices, as well as of the seismic excitation, i.e. the slenderness of the body and the peak ground acceleration. The data needed to develop the probabilistic model are obtained integrating the nonlinear equations of motion of the two systems subject to selected ground motions. In the end, some numerical examples are proposed

Large-scale implementation of a new TDR-based system for the monitoring of pipe leaks

In this paper, the practical implementation of an innovative time domain reflectometry (TDR)-based system for leak detection in underground water pipes is presented. This system, which had been previously developed and experimented on pilot plants, has now been installed (for the first time) on a large scale, in 10 km of pipes. The present work describes all the practical aspects and technical details (from the design to the functional tests), related to the implementation of the system

Wetenschap met de ramen wijd open: tien lessen voor wie impact wil maken

In tien lessen geven door de wol geverfde sociale en geesteswetenschappers handvatten aan collega’s die impact willen maken met hun onderzoek. In een nieuwe brochure, een uitgave van de Sociaal-Wetenschappelijke Raad van de KNAW, pleiten ze voor meer waardering voor impact en geven ze praktische handvatten om aan de slag te gaan. Wetenschap met de ramen wijd open, tien lessen voor wie impact wil maken is een uitgave van de Sociaal-Wetenschappelijke Raad van de Koninklijke Nederlandse Akademie voor Wetenschappen (KNAW). De brochure is geschreven door Godfried Engbersen, Andrea Evers, Beatrice de Graaf, Paul ’t Hart, Anita Jansen, Lotte Jensen, Leo Lucassen en Maarten Prak, allen hoogleraar in de sociale of geesteswetenschappen. De gedrukte brochure wordt in het Nederlands verspreid over alle faculteiten

Multi-ancestry study of blood lipid levels identifies four loci interacting with physical activity.

Many genetic loci affect circulating lipid levels, but it remains unknown whether lifestyle factors, such as physical activity, modify these genetic effects. To identify lipid loci interacting with physical activity, we performed genome-wide analyses of circulating HDL cholesterol, LDL cholesterol, and triglyceride levels in up to 120,979 individuals of European, African, Asian, Hispanic, and Brazilian ancestry, with follow-up of suggestive associations in an additional 131,012 individuals. We find four loci, in/near CLASP1, LHX1, SNTA1, and CNTNAP2, that are associated with circulating lipid levels through interaction with physical activity; higher levels of physical activity enhance the HDL cholesterol-increasing effects of the CLASP1, LHX1, and SNTA1 loci and attenuate the LDL cholesterol-increasing effect of the CNTNAP2 locus. The CLASP1, LHX1, and SNTA1 regions harbor genes linked to muscle function and lipid metabolism. Our results elucidate the role of physical activity interactions in the genetic contribution to blood lipid levels

A Delphi Survey Study to Formulate Statements on the Treatability of Inherited Metabolic Disorders to Decide on Eligibility for Newborn Screening

The Wilson and Jungner (W&amp;J) and Andermann criteria are meant to help select diseases eligible for population-based screening. With the introduction of next-generation sequencing (NGS) methods for newborn screening (NBS), more inherited metabolic diseases (IMDs) can technically be included, and a revision of the criteria was attempted. This study aimed to formulate statements and investigate whether those statements could elaborate on the criterion of treatability for IMDs to decide on eligibility for NBS. An online Delphi study was started among a panel of Dutch IMD experts (EPs). EPs evaluated, amended, and approved statements on treatability that were subsequently applied to 10 IMDs. After two rounds of Delphi, consensus was reached on 10 statements. Application of these statements selected 5 out of 10 IMDs proposed for this study as eligible for NBS, including 3 IMDs in the current Dutch NBS. The statement: ‘The expected benefit/burden ratio of early treatment is positive and results in a significant health outcome’ contributed most to decision-making. Our Delphi study resulted in 10 statements that can help to decide on eligibility for inclusion in NBS based on treatability, also showing that other criteria could be handled in a comparable way. Validation of the statements is required before these can be applied as guidance to authorities.</p

Surface nanophotonics with Bloch waves on dielectric multilayers

Planar mutilayers sustaining either TE or TM polarized Bloch Surface Waves (BSWs) offer new opportunities for management of light at the nanoscale. We will discuss how BSWs can be exploited in guiding and confining light on nanometric relieves, enhancing fluorescence emission and providing additional features for plasmonic nano-antennas

Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV

We report the first measurement of charged particle elliptic flow in Pb-Pb collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurement is performed in the central pseudorapidity region (|$\eta$|<0.8) and transverse momentum range 0.2< $p_{\rm T}$< 5.0 GeV/$c$. The elliptic flow signal v$_2$, measured using the 4-particle correlation method, averaged over transverse momentum and pseudorapidity is 0.087 $\pm$ 0.002 (stat) $\pm$ 0.004 (syst) in the 40-50% centrality class. The differential elliptic flow v$_2(p_{\rm T})$ reaches a maximum of 0.2 near $p_{\rm T}$ = 3 GeV/$c$. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow increases by about 30%. Some hydrodynamic model predictions which include viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/389