Further comments on the background field method and gauge invariant effective actions

The aim of this paper is to give a firm and clear proof of the existence in the background field framework of a gauge invariant effective action for any gauge theory ({\it background gauge equivalence}). Here by effective action we mean a functional whose Legendre transform restricted to the physical shell generates the matrix elements of the connected $S$-matrix. We resume and clarify a former argument due to Abbott, Grisaru and Schaefer based on the gauge-artifact nature of the background fields and on the identification of the gauge invariant effective action with the generator of the proper, background field, vertices.Comment: 21 pages, Latex 2

A Functional and Lagrangian Formulation of Two-Dimensional Topological Gravity

We reconsider two-dimensional topological gravity in a functional and lagrangian framework. We derive its Slavnov-Taylor identities and discuss its (in)dependence on the background gauge. Correlators of reparamerization invariant observables are shown to be globally defined forms on moduli space. The potential obstruction to their gauge-independence is the non-triviality of the line bundle on moduli space ${\cal L}_x$, whose first Chern-class is associated to the topological invariants of Mumford, Morita and Miller. Based on talks given at the Fubini Fest, Torino, 24-26 February 1994, and at the Workshop on String Theory, Trieste, 20-22 April 1994.Comment: 11 pages, harvmac, CERN-TH-7302/94, GEF-Th-6/199

Training Designers of the Future: Reflections on a Didactic Case ‘Made in Italy’

Focusing on a specific case, the postgraduate course Product Service System Design taught in English to Italian and international students of the Design Facult y at Milan Pol ytechnic, the author reflects on the present and future of designers as ‘reflexive professionals’ (to quote Donald A. Schön1) called upon to act in uncertain and vaguely defined contexts, tackle problems in highly original ways and come up with wide -ranging, experimental and innovative solutions resorting to complex and hybrid techniques and tools either purposely designed or taken from other fields

Wind loads analysis at the anchorages of the Talavera de la Reina cable stayed bridge

This paper describes wind tunnel tests performed on wind tunnel models of the Talavera de la Reina cable stayed bridge. The work describes the aeroelastic model construction and it is focused on the evaluation and analysis of the mean and peak wind loads at the tower foundation and the cable anchorages since these data can be very useful by the bridge manufacturer as a support for the bridge design. The work is part of a complete wind tunnel study carried out to analyze the aeroelastic stability of the bridge

A graph-dynamical interpretation of Kiselman's semigroups

A Sequential Dynamical System (SDS) is a quadruple (\Gamma, S_i,f_i,w) consisting of a (directed) graph \Gamma=(V,E), each of whose vertices i\in V is endowed with a finite set state S_i and an update function f_i: \prod_{j, i \to j} S_j \to S_i --- we call this structure an {\em update system} --- and a word w in the free monoid over V, specifying the order in which update functions are to be performed. Each word induces an evolution of the system and in this paper we are interested in the dynamics monoid, whose elements are all possible evolutions. When \Gamma is a directed acyclic graph, the dynamics monoid of every update system supported on \Gamma naturally arises as a quotient of the Hecke-Kiselman monoid associated with \Gamma. In the special case where \Gamma = \Gamma_n is the complete oriented acyclic graph on n vertices, we exhibit an update system whose dynamics monoid coincides with Kiselman's semigroup K_n, thus showing that the defining Hecke-Kiselman relations are optimal in this situation. We then speculate on how these results may extend to the general acyclic case.Comment: 14 pages. This is a substantial revision of the previous version. Proofs and exposition have been simplified. The title has been changed to better reflect the content of the pape

dynamic simulation and critical assessment of a composite bridge in high speed railway

Abstract Evaluation of critical responses of a bridge including resonances in high-speed (HS) railway is a dominant issue in order to confirm the structural safety of bridge and the stability of ballast on bridge deck. In numerical way for critical assessment, it is important to make a sophisticated numerical model and considering the variation of actual properties of structural members. This study proposed a train-track-bridge interaction model focusing on Sesia viaduct, and calibrated the model properties as matching these modal characteristics and dynamic responses to measured ones. By the numerical and experimental comparison, calibrated model could reproduce accelerations up to 30 Hz both of on the time and frequency domains accurately. Especially, good agreements on sleeper accelerations can indicate the high reproducibility of interaction force, which is one of key factors of train-track-bridge interaction simulation. Numerical computation by calibrated model clarified that the deck acceleration up to 30Hz increases by seventh and eighth resonances between passing vehicle length and structural modes, not only global third bending or third torsional but also high order local deck modes. In addition, high performance computing technique based on super computer in RTRI was adopted for parametric analysis in order to investigate the requirements to realize highly accurate estimation for the maximum deck acceleration by the numerical way. As the results of parametric study focusing on design assumption, calculation modal order and train/bridge interaction, it was clarified that the design model causes overestimation by twice maximum acceleration on the deck, and the amplification of excitation forces caused by passage on deflected rails, which is considered in high-order modes and train/bridge interaction, is a key factor to achieve accurate deck acceleration evaluation

A New Approach: Determining cyt b G143A Allele Frequency in Zymoseptoria tritici by Digital Droplet PCR

Z. tritici first appeared in Italy later than in northern-central European countries. QoIs fungicides currently play a role in STB control, used in combination with Demethylation Inhibitors (DMIs) or Succinate dehydrogenase Inhibitors (SDHIs). In this study, we set up a fast, sensitive, and accurate ddPCR protocol in order to investigate the presence and frequency of G143A substitution, causing a reduction in strobilurins’ efficacy in Z. tritici. The best PCR conditions for the clear separation of positive and negative droplets were identified. The lowest wild-type and resistant alleles frequencies were accurately determined on samples consisting of mixed DNAs from monoconidial cultures of Z. tritici and were expressed as fractional abundance. The protocol was tested by determining the copy number and frequency of alleles on gDNA purified in three Italian Z. tritici field populations representative of different fungicide management strategies. For the first time, the determination of allele concentration and the frequency of a mutation involved in Z. tritici fungicide resistance was carried out by employing digital PCR. This new approach provides a diagnostic tool that is rapid and able to detect very low G143A substitution percentages, which is very useful for fungicide resistance detection at early stages, thus, informing field management strategies for contrasting STB disease

SafeOCS Industry Safety Data: The Value Proposition for the Oil & Gas Industry

PresentationThis paper summarizes efforts by the U.S. Department of Transportation, Bureau of Transportation Statistics (BTS) to develop and manage an industry-wide safety data framework under an agreement with the U.S. Department of the Interior’s Bureau of Safety and Environmental Enforcement (BSEE). The Industry Safety Data (ISD) program provides a trusted, proactive means for the oil and gas industry to voluntarily and securely report safety information to identify early warnings of safety problems by uncovering hidden at-risk conditions not previously exposed from analysis of reportable accidents and incidents. Besides agency-reportable incidents, this program captures near miss and other significant safety event information that is maintained by individual companies as part of their internal safety programs. Phase I of this program was completed in June 2019, and plans are progressing to expand industry participation. Companies have long realized the benefits of collecting and analyzing data around safety and environmental incidents to identify risk, then develop systems and processes to prevent recurrence. These activities have been supported and supplemented by industry associations that collect and share event information and develop recommended practices to aid in performance improvement. In high-reliability industries, such as aviation and nuclear, it is common practice to report and share events among companies and regulators to identify hidden trends and create or update existing recommended practices or regulations. The challenge for the oil and gas industry operating within the U.S. Gulf of Mexico Outer Continental Shelf (OCS) was that, while industry associations and the regulator were collecting data on significant incidents, lesser safety events or observed unsafe conditions/behaviors are not required to be reported and therefore may go unnoticed as a trend until a major event occurs. This represented an opportunity for industry, BSEE, and BTS to collaborate on a means of gathering incident data that would allow for analysis and identification of trends or events of significance enabling appropriate interventions to prevent major incidents. The value proposition of this effort is development of a comprehensive safety data repository that facilitates the continual improvement in safety and environmental performance from the implementation of learnings shared from trends or lesser incidents and events occurring within industry

Damage identification in warren truss bridges by two different time–frequency algorithms

Recently, a number of authors have been focusing on drive-by monitoring methods, exploiting sensors mounted on the vehicle rather than on the bridge to be monitored, with clear advantages in terms of cost and flexibility. This work aims at further exploring the feasibility and effectiveness of novel tools for indirect health monitoring of railway structures, by introducing a higher level of accuracy in damage modelling, achieve more close-to-reality results. A numerical study is carried out by means of a FE 3D model of a short span Warren truss bridge, simulating the dynamic interaction of the bridge/track/train structure. Two kinds of defects are simulated, the first one affecting the connection between the lower chord and the side diagonal member, the second one involving the joint between the cross-girder and the lower chord. Accelerations gathered from the train bogie in different working conditions and for different intensities of the damage level are analyzed through two time-frequency algorithms, namely Continuous Wavelet and Huang-Hilbert transforms, to evaluate their robustness to disturbing factors. Compared to previous studies, a complete 3D model of the rail vehicle, together with a 3D structural scheme of the bridge in place of the 2D equivalent scheme widely adopted in the literature, allow a more detailed and realistic representation of the effects of the bridge damage on the vehicle dynamics. Good numerical results are obtained from both the two algorithms in the case of the time-invariant track profile, whereas the Continuous Wavelet Transform is found to be more robust when a deterioration of track irregularity is simulated