Abelian link invariants and homology

We consider the link invariants defined by the quantum Chern-Simons field theory with compact gauge group U(1) in a closed oriented 3-manifold M. The relation of the abelian link invariants with the homology group of the complement of the links is discussed. We prove that, when M is a homology sphere or when a link -in a generic manifold M- is homologically trivial, the associated observables coincide with the observables of the sphere S^3. Finally we show that the U(1) Reshetikhin-Turaev surgery invariant of the manifold M is not a function of the homology group only, nor a function of the homotopy type of M alone.Comment: 18 pages, 3 figures; to be published in Journal of Mathematical Physic

Classical Teichmuller theory and (2+1) gravity

We consider classical Teichmuller theory and the geodesic flow on the cotangent bundle of the Teichmuller space. We show that the corresponding orbits provide a canonical description of certain (2+1) gravity systems in which a set of point-like particles evolve in universes with topology S_g x R where S_g is a Riemann surface of genus g >1. We construct an explicit York's slicing presentation of the associated spacetimes, we give an interpretation of the asymptotic states in terms of measured foliations and discuss the structure of the phase spaces

Deligne-Beilinson cohomology and abelian link invariants: torsion case

For the abelian Chern-Simons field theory, we consider the quantum functional integration over the Deligne-Beilinson cohomology classes and present an explicit path-integral non-perturbative computation of the Chern-Simons link invariants in $SO(3)\simeq\mathbb{R}P^3$, a toy example of 3-manifold with torsion

Low salinity waterflooding for Enhanced Oil Recovery - stochastic model calibration and uncertainty quantification

We focus on key aspects related to the quantification of the uncertainty associated with modeling of Enhanced Oil Recovery (EOR) through Low Salinity (LS) water injection in a reservoir. Low salinity waterflooding is an emerging EOR technique in which the salinity of the injected water is controlled to improve oil recovery, as opposed to conventional waterflooding where brine is usually used. Several mechanisms have been proposed to underpin the processes leading to additional oil mobility, but none of them has been conclusively identified as the key driving cause. Literature results suggest that LS water causes an alteration of the wettability of the porous medium, leading to more favorable conditions for oil recovery. In this context, simulation models that represent the process using salinity-dependent relative permeabilities have been developed. Here, we consider a tertiary coreflood experiment performed at Eni laboratory facilities through LS water injection, following sea water flooding. Oil and water relative permeability curves are parameterized through the Corey model. Model parameters and their uncertainties are estimated within a stochastic inverse modeling approach, upon relying on a classical reservoir simulator to simulate the measured oil recovery. The likelihood function is maximized through a joint use of the Latin hypercube sampling and the Metropolis Hastings algorithm, while the process model is coupled with a universal Kriging technique. The posterior sample of model parameters is then employed to quantify uncertainty propagation to a sector model of a selected North-East African sandstone reservoir. This enables us to quantify the impact of parameter uncertainty on the expected oil production resulting from a field scale application of the technique under study. The reservoir simulation reveals the potential of the LS water injection technique to improve the recovery in the considered field

Fibre-reinforced polymer strengthening of substandard lap-spliced reinforced concrete members: A comprehensive survey

Externally bonded Fibre Reinforced Polymer (FRP) confinement is extensively used to improve the bond strength of substandard lap spliced steel bars embedded in reinforced concrete (RC) components. However, the test results from bond tests on such bond-deficient components are not fully conclusive, which is reflected in the few design guidelines available for FRP strengthening. For the first time, this article presents a comprehensive survey on FRP strengthening of substandard lap-spliced RC members, with emphasis on the adopted experimental methodologies and analytical approaches developed to assess the effectiveness of FRP in controlling bond-splitting failures. The main findings and shortcomings of previous investigations are critically discussed and further research needs are identified. This review contributes towards the harmonisation of testing procedures so as to facilitate the development of more accurate predictive models, thus leading to more cost-effective strengthening interventions

Deflection behaviour of FRP reinforced concrete beams and slabs: An experimental investigation

The flexural response of FRP RC elements is investigated through load–deflection tests on 24 RC beams and slabs with glass FRP (GFRP) and carbon FRP (CFRP) reinforcement covering a wide range of reinforcement ratios. Rebar and concrete strains around a crack inducer are used to establish moment–curvature relationships and evaluate the shear and flexural components of mid-span deflections. It is concluded that the contribution of shear and bond induced deformations can be of major significance in FRP RC elements having moderate to high reinforcement ratios. Existing equations to calculate short-term deflection of FRP RC elements are discussed and compared to experimental values

Full-Scale Shaking Table Tests on Deficient Rc Buildings Strengthened With FRP Composites

The paper discusses the results from experimental programmes including full-scale shaking table tests on two deficient one-span two-storey RC frame buildings strengthened with Carbon Fibre Reinforced Polymer (CFRP) composites. The tests were performed at one of the world class shaking table testing facility, the AZALEE shake table at the Commissariat à l’Énergie Atomique (CEA), Laboratory in Saclay, France, as part of two European (EU) funded research projects (EU ECOLEADER project and EU FP7 SERIES/ BANDIT project). The aim of these experimental programmes was to investigate the effectiveness of externally bonded CFRP reinforcement in improving the seismic behaviour of deficiently designed RC buildings. To simulate typical substandard design, the reinforcement of beam-column joints and columns of the two full-scale frames had inadequate detailing. In both projects, initial shaking table tests were carried out to assess the seismic behaviour of the bare frame buildings. Columns and joints were subsequently repaired and strengthened using CFRP composite material for the ECOLEADER frame, and a strengthening solution consisting of CFRP composite material and Post-Tensioned Metal Straps for the BANDIT frame. The frames were then subjected to incremental seismic excitations to assess the effectiveness of the strengthening solutions in improving the global and local frame performance. Whilst the original bare frames were significantly damaged at a peak ground acceleration (PGA) of 0.15-0.20g, the strengthened frames resisted severe shaking table tests up to PGA=0.50-0.60g without failure. Moreover, the strengthening interventions enhanced the interstorey drift ratio capacity and proved to be very effective in addressing the seismic deficiencies of substandard buildings

Three-manifold invariant from functional integration

We give a precise definition and produce a path-integral computation of the normalized partition function of the abelian U(1) Chern-Simons field theory defined in a general closed oriented 3-manifold. We use the Deligne-Beilinson formalism, we sum over the inequivalent U(1) principal bundles over the manifold and, for each bundle, we integrate over the gauge orbits of the associated connection 1- forms. The result of the functional integration is compared with the abelian U(1) Reshetikhin-Turaev surgery invariant

A practical creep model for concrete elements under eccentric compression

Many prestressed concrete bridges are reported to suffer from excessive vertical deflections and cracking during their service life. Creep softens the structure significantly, and therefore an accurate prediction of creep is necessary to determine long-term deflections in elements under eccentric axial compression such as prestressed concrete girders. This study proposes a modification to the creep damage model of Model Code 2010 to account for the effect of load eccentricity. The modified creep model considers damage due to differential drying shrinkage. Initially, the creep behaviour of small scale concrete specimens under eccentric compression load is investigated experimentally. Twelve small-scale concrete prisms were subjected to eccentric axial loading to assess their shrinkage and creep behaviour. The main parameters investigated include the load eccentricity and exposure conditions. Based on the experimental results, an inverse analysis is conducted to determine the main parameters of the modified creep model. Subsequently, a numerical hygro-mechanical simulation is carried out to examine the effect of load eccentricity on the development of shrinkage and creep, and on the interaction between drying, damage and creep. The results indicate that eccentric loading leads to different tensile and compressive creep through the cross section, which contradicts the current design approach that assumes that tensile and compressive creep are identical. The proposed model also predicts accurately the long-term behaviour of tests on reinforced concrete elements available in the literature. This study contributes towards further understanding of the long-term behaviour of concrete structures, and towards the development of advanced creep models for the design/assessment of concrete structures

Bardeen-Anomaly and Wess-Zumino Term in the Supersymmetric Standard Model

We construct the Bardeen anomaly and its related Wess-Zumino term in the supersymmetric standard model. In particular we show that it can be written in terms of a composite linear superfield related to supersymmetrized Chern-Simons forms, in very much the same way as the Green-Schwarz term in four-dimensional string theory. Some physical applications, such as the contribution to the g-2 of gauginos when a heavy top is integrated out, are briefly discussed.Comment: 21 pages, (plain TeX), CERN.TH-6845/93, DFPD 93/TH/32, UCLA/93/TEP/13, NYU-TH-93/10/01, ENSLAPP-A442/9