NUMERICAL SIMULATION STUDY OF VIBRATION MITIGATION EFFECTIVENESS OF TUNED MASS DAMPERS FOR TRAFFIC SIGNAL MAST ARM STRUCTURES

Fatigue damage in the connections of single mast arm signal support structures is one of the primary safety concerns because collapse could result from fatigue induced cracking. This type of cantilever signal support structures typically has very light damping and excessively large wind-induced vibration have been observed. Major changes related to fatigue design were made in the 2001 AASHTO LRFD Specification for Structural Supports for Highway Signs, Luminaries, and Traffic Signals and supplemental damping devices have been shown to be promising in reducing the vibration response and thus fatigue load demand on mast arm signal support structures. The primary objective of this study is to investigate the effectiveness and optimal use of one type of damping devices termed tuned mass damper (TMD) in vibration response mitigation. Three prototype single mast arm signal support structures with 50-ft, 60-ft, and 70-ft respectively are selected for this numerical simulation study. In order to validate the finite element models for subsequent simulation study, analytical modeling of static deflection response of mast arm of the signal support structures was performed and found to be close to the numerical simulation results from beam element based finite element model. A 3-DOF dynamic model was then built using analytically derived stiffness matrix for modal analysis and time history analysis. The free vibration response and forced (harmonic) vibration response of the mast arm structures from the finite element model are observed to be in good agreement with the finite element analysis results. Furthermore, experimental test result from recent free vibration test of a full-scale 50-ft mast arm specimen in the lab is used to verify the prototype structure’s fundamental frequency and viscous damping ratio. After validating the finite element models, a series of parametric study were conducted to examine the trend and determine optimal use of tuned mass damper on the prototype single mast arm signal support structures by varying the following parameters: mass, frequency, viscous damping ratio, and location of TMD. The numerical simulation study results reveal that two parameters that influence most the vibration mitigation effectiveness of TMD on the single mast arm signal pole structures are the TMD frequency and its viscous damping ratio.

Productivity growth and the structure of production

In this study, interactions between potential hierarchical value chains existing in the production structure and industry-wise productivity growths are sought. We applied generalized Chenery-Watanabe heuristics for matrix linearity maximization to triangulate the input-output incidence matrix for both Japan and the Republic of Korea, finding the potential directed flow of values spanning the industrial sectors of the basic (disaggregated) industry classifications for both countries. Sector specific productivity growths were measured by way of the Trönquvist index, using the 2000-2005 linked input-output tables for both Japan and Korea.

The subjunctive mood in Late Middle English adverbial clauses: the interaction of form and function

This thesis focuses on the history of the inflexional subjunctive and its functional substitutes in Late Middle English. To explore why and how the inflexional subjunctive declined in the history of English language, I analysed 2653 examples of three adverbial clauses introduced by if (1882 examples), though (305 examples) and lest (466 examples). Using a corpus-based approach, this thesis argues that linguistic change in subjunctive constructions did not happen suddenly but rather gradually, and the way it changed was varied , and that different constructions changed at different speeds in different environments. It is well known that the inflexional subjunctive declined in the history of English, mainly because of inflexional loss. Strangely however this topic has been comparatively neglected in the scholarly literature, especially with regard to the Middle English period, probably due to the limitations of data and also because study of this development requires very cumbersome textual research. This thesis has derived and analysed the data from three large corpora in the public domain: the Middle English Grammar Corpus (MEG-C for short), the Innsbruck Computer Archive of Machine-Readable English Texts (ICAMET for short), and some selected texts from The Corpus of Middle English Prose and Verse, part of the Middle English Compendium that also includes the Middle English Dictionary. The data were analysed from three perspectives: 1) clausal type, 2) dialect, and 3) textual genre. The basic methodology for the research was to analyse the examples one by one, with special attention being paid to the peculiarities of each text. In addition, this thesis draw on some complementary – indeed overlapping -- linguistic theories for further discussion: 1) Biber’s multi-dimensional theory, 2) Ogura and Wang’s (1994) S-curve or ‘diffusion’ theory, 3) Kretzchmar’s (2009) linguistics of speech, and 4) Halliday’s (1987) notion of language as a dynamic open system. To summarise the outcomes of this thesis: 1) On variation between clausal types, it was shown that the distributional tendencies of verb types (sub, ind, mod) are different between the three adverbial clauses under consideration. 2) On variation between dialects, it has been shown that the northern area, i.e. the so-called Great Scandinavian Belt, displays an especially high comparative ratio of the inflexional subjunctive construction compared to the other areas. This thesis suggests that this result was caused by the influence of Norse, relating the finding to the argument of Samuels (1989) that the present tense -es ending in the northern dialect was introduced by the influence of the Scandinavians. 3) On variation between genres, those labelled Science, Documents and Religion display relatively high ratio of the inflexional subjunctive, while Letter, Romance and History show relatively low ratio of the inflexional subjunctive. This results are explained by Biber’s multi-dimensional theory, which shows that the inflexional subjunctive can be related to the factors ‘informational’, ‘non-narrative’, ‘persuasive’ and ‘abstract’. 4) Lastly, on the inflexional subjunctive in Late Middle English, this thesis concludes that 1) the change did not happen suddenly but gradually, and 2) the way language changes varies. Thus the inflexional subjunctive did not disappear suddenly from England, and there was a time lag among the clausal types, dialects and genres, which can be related to Ogura and Wang’s S-curve (“diffusion”) theory and Kretzchmars’s view of “linguistic continuum”. This thesis has shown that the issues with regard to the inflexional subjunctive are quite complex, so that research in this area requires not only textual analysis but also theoretical analysis, considering both intra- and extra- linguistic factors.

Embedded systems and advanced signal processing for Acousto- Ultrasonic Inspections

Non Destructive Testing (NDT) and Structural Health Monitoring (SHM) are becoming essential in many application contexts, e.g. civil, industrial, aerospace etc., to reduce structures maintenance costs and improve safety. Conventional inspection methods typically exploit bulky and expensive instruments and rely on highly demanding signal processing techniques. The pressing need to overcome these limitations is the common thread that guided the work presented in this Thesis. In the first part, a scalable, low-cost and multi-sensors smart sensor network is introduced. The capability of this technology to carry out accurate modal analysis on structures undergoing flexural vibrations has been validated by means of two experimental campaigns. Then, the suitability of low-cost piezoelectric disks in modal analysis has been demonstrated. To enable the use of this kind of sensing technology in such non conventional applications, ad hoc data merging algorithms have been developed. In the second part, instead, imaging algorithms for Lamb waves inspection (namely DMAS and DS-DMAS) have been implemented and validated. Results show that DMAS outperforms the canonical Delay and Sum (DAS) approach in terms of image resolution and contrast. Similarly, DS-DMAS can achieve better results than both DMAS and DAS by suppressing artefacts and noise. To exploit the full potential of these procedures, accurate group velocity estimations are required. Thus, novel wavefield analysis tools that can address the estimation of the dispersion curves from SLDV acquisitions have been investigated. An image segmentation technique (called DRLSE) was exploited in the k-space to draw out the wavenumber profile. The DRLSE method was compared with compressive sensing methods to extract the group and phase velocity information. The validation, performed on three different carbon fibre plates, showed that the proposed solutions can accurately determine the wavenumber and velocities in polar coordinates at multiple excitation frequencies.

Comparison of the seismic performances of a steel frame building equipped with different geometrical configurations of Crescent Shaped Braces

The Crescent Shaped Brace (CSB) is a new simple steel hysteretic device proposed to be used as an enhanced diagonal brace in framed structures. The CSB allows the practical designer to choose the lateral stiffness independently from the yield strength of the device, due to its peculiar ad-hoc shape. In the present thesis, a complete study referring to different CSB configurations has been presented. After the validation of the hysteretic capacities of the Crescent Shaped Braces, the seismic concept of the "enhanced first story isolation" system has been proposed within the PBSD. It relies on the total separation between the Vertical Resisting System (VRS) and the Horizontal Resisting System (HRS) in order to attain a certain objective curve of the structure. An applicative example has been studied following this concept and exploiting the advantages of the CSBs as seismic dissipative devices used for the HRS. Then several geometrical configurations called Single CSB system, Single 2 CSB system, Double CSB system, Coupled CSB system, Coupled with high length CSB system, and the final one was Cross bracing system have been introduced and modelled with SAP2000 and the results have been compared.

Structural decomposition analysis and input-output subsystems: An application to Spanish CO2 emissions

Analysis of gas emissions by the input-output subsystem approach provides detailed insight into pollution generation in an economy. Structural decomposition analysis, on the other hand, identifies the factors behind the changes in key variables over time. Extending the input-output subsystem model to account for the changes in these variables reveals the channels by which environmental burdens are caused and transmitted throughout the production system. In this paper we propose a decomposition of the changes in the components of CO2 emissions captured by an input-output subsystems representation. The empirical application is for the Spanish service sector, and the economic and environmental data are for years 1990 and 2000. Our results show that services increased their CO2 emissions mainly because of a rise in emissions generated by non-services to cover the final demand for services. In all service activities, the decomposed effects show an increase in CO2 emissions due to a decrease in emission coefficients (i.e., emissions per unit of output) compensated by an increase in emissions caused both by the input-output coefficients and the rise in demand for services. Finally, large asymmetries exist not only in the quantitative changes in the CO2 emissions of the various services but also in the decomposed effects of these changes. Keywords: structural decomposition analysis, input-output subsystems, CO2 emissions, service sector.

Production Networks and Spatial Economic Interdependence: An International Input-Output Analysis of the Asia-Pacific Region

The Asia-Pacific Region has enjoyed remarkable economic growth in the last three decades. This rapid economic growth can be partially attributed to the global spread of production networks, which has brought about major changes in spatial interdependence among economies within the region. By applying an Input-Output based spatial decomposition technique to the Asian International Input-Output Tables for 1985 and 2000, this paper not only analyzes the intrinsic mechanism of spatial economic interdependence, but also shows how value added, employment and CO2 emissions induced are distributed within the international production networks.

China's regional economies and value chains : an interregional input-output analysis

Attempts to understand China’s role in global value chains have often noted the case of Apple's iPhone production, in particular the fact that the value added during the Chinese portion of the iPhone’s supply chain is no more than 4%. However, when we examine the Chinese economy as a whole in global production networks, China’s share in total induced value added by China’s exports of final products to the USA is about 75% in 2005. This leads us to investigate how Chinese value added is created and distributed not only internationally but also domestically. To elucidate the increasing complexity of China’s domestic production networks, this paper focuses on the measure of Domestic Value Chains (DVCs) across regions and their linkages with global markets. By using China’s 1997 and 2007 interregional input-output tables, we can understand in detail the structural changes in domestic trade in terms of value added, as well as the position and degree of participation of different regions within the DVCs.

Compilation of a regionally-extended inter-country input-output table and its application to global value chain analysis

Studies on the rise of global value chains (GVCs) have attracted a great deal of interest in the recent economics literature. However, due to statistical and methodological challenges, most existing research ignores domestic regional heterogeneity in assessing the impact of joining GVCs. GVCs are supported not only directly by domestic regions that export goods and services to the world market, but also indirectly by other domestic regions that provide parts, components, and intermediate services to final exporting regions. To better understand the nature of a country's position and degree of participation in GVCs, we need to fully examine the role of individual domestic regions. Understanding the domestic components of GVCs is especially important for larger economies such as China, the US, India and Japan, where there may be large variations in economic scale, geography of manufacturing, and development stages at the domestic regional level. This paper proposes a new framework for measuring domestic linkages to global value chains. This framework measures domestic linkages by endogenously embedding a target country's (e.g. China and Japan) domestic interregional input–output tables into the OECD inter-country input–output model. Using this framework, we can more clearly understand how global production is fragmented and extended internationally and domestically.

Numerical analysis of the modal coupling at low resonances in a Colombian Andean Bandola in C using the finite element method

The work presented in this thesis is concerned with the dynamical behavior of a CBandola's acoustical box at low resonances -- Two models consisting of two and three coupled oscillators are proposed in order to analyse the response at the first two and three resonances, respectively -- These models describe the first resonances in a bandola as a combination of the lowest modes of vibration of enclosed air, top and back plates -- Physically, the coupling between these elements is caused by the fluid-structure interaction that gives rise to coupled modes of vibration for the assembled resonance box -- In this sense, the coupling in the models is expressed in terms of the ratio of effective areas and masses of the elements which is an useful parameter to control the coupling -- Numerical models are developed for the analysis of modal coupling which is performed using the Finite Element Method -- First, it is analysed the modal behavior of separate elements: enclosed air, top plate and back plate -- This step is important to identify participating modes in the coupling -- Then, a numerical model of the resonance box is used to compute the coupled modes -- The computation of normal modes of vibration was executed in the frequency range of 0-800Hz -- Although the introduced models of coupled oscillators only predict maximum the first three resonances, they also allow to study qualitatively the coupling between the rest of the computed modes in the range -- Considering that dynamic response of a structure can be described in terms of the modal parameters, this work represents, in a good approach, the basic behavior of a CBandola, although experimental measurements are suggested as further work to verify the obtained results and get more information about some characteristics of the coupled modes, for instance, the phase of vibration of the air mode and the radiation e ciency

XSophe-Sophe-XeprView (R). A computer simulation software suite (v. 1.1.3) for the analysis of continuous wave EPR spectra

The XSophe-Sophe-XeprView((R)) computer simulation software suite enables scientists to easily determine spin Hamiltonian parameters from isotropic, randomly oriented and single crystal continuous wave electron paramagnetic resonance (CW EPR) spectra from radicals and isolated paramagnetic metal ion centers or clusters found in metalloproteins, chemical systems and materials science. XSophe provides an X-windows graphical user interface to the Sophe programme and allows: creation of multiple input files, local and remote execution of Sophe, the display of sophelog (output from Sophe) and input parameters/files. Sophe is a sophisticated computer simulation software programme employing a number of innovative technologies including; the Sydney OPera HousE (SOPHE) partition and interpolation schemes, a field segmentation algorithm, the mosaic misorientation linewidth model, parallelization and spectral optimisation. In conjunction with the SOPHE partition scheme and the field segmentation algorithm, the SOPHE interpolation scheme and the mosaic misorientation linewidth model greatly increase the speed of simulations for most spin systems. Employing brute force matrix diagonalization in the simulation of an EPR spectrum from a high spin Cr(III) complex with the spin Hamiltonian parameters g(e) = 2.00, D = 0.10 cm(-1), E/D = 0.25, A(x) = 120.0, A(y) = 120.0, A(z) = 240.0 x 10(-4) cm(-1) requires a SOPHE grid size of N = 400 (to produce a good signal to noise ratio) and takes 229.47 s. In contrast the use of either the SOPHE interpolation scheme or the mosaic misorientation linewidth model requires a SOPHE grid size of only N = 18 and takes 44.08 and 0.79 s, respectively. Results from Sophe are transferred via the Common Object Request Broker Architecture (CORBA) to XSophe and subsequently to XeprView((R)) where the simulated CW EPR spectra (1D and 2D) can be compared to the experimental spectra. Energy level diagrams, transition roadmaps and transition surfaces aid the interpretation of complicated randomly oriented CW EPR spectra and can be viewed with a web browser and an OpenInventor scene graph viewer.

The English-only movement: A communication analysis of changing perceptions of language vitality

This paper reexamines the potential impact of the English-only movement on linguistic minorities and Anglos' perceptions of their own and minority groups' language vitality. Of particular interest is the Hispanic population-the fastest growing minority in the U.S. Communication scholars have paid only scant attention to the English-only movement and how it affects the social and communication climate for Latinos. However, literature reviews prepared for the American Psychological Association and for the Teachers of English to Speakers of Other Languages (in 1991 and 1995, respectively) concluded that English-only initiatives have negative consequences for limited-English proficiency groups. Revisiting this still-growing issue in the light of more recent studies across disciplines and media reports, we examine how Anglo support for English-only policies limits the use, promotion, and salience of minority languages like Spanish in institutional settings and in the linguistic landscape and suggest directions for future research.

Modelação e monitorização do comportamento dinâmico de barragens abóbada: identificação modal automática

Trabalho Final de Mestrado elaborado no Laboratório de Engenharia Civil (LNEC) para obtenção do grau de Mestre em Engenharia Civil pelo Instituto Superior de Engenharia de Lisboa no âmbito do protocolo de cooperação entre o ISEL e o LNEC

Tools for simulation output analysis

This technical report presents a description of the output data files and the tools used to validate and to extract information from the output data files generated by the Repeater-Based Hybrid Wired/Wireless Network Simulator and the Bridge-Based Hybrid Wired/Wireless Network Simulator.