A light-scattering study of the kinetic size distribution changes of aerosols

Imperial Users onl

Why Don't Foreign Firms Cooperate in U.S. Antidumping Investigations?: An Emperical Analysis

Foreign firms face punitive duties if they do not cooperate with the US Department of Commerce (DOC) in antidumping procedures. For example, 37% of all foreign firms involved in antidumping investigations in the US chose faced “facts available” margins for the 1995-2002 period, with average antidumping duties of 31% for cooperating foreign firms, compared to 87% for those who do not. The existing literature has focused on how DOC discretion has led to foreign firm non-cooperation. This paper instead examines individual foreign firm’s decisions about whether to cooperate during this same period. We find evidence that non-cooperation is consistent with a model of foreign firms rationally choosing not to cooperate, rather than solely as a result of investigating authority bias against imports.antidumping, commercial policy, trade policy, facts available

Las revistas del siglo XVIII y el concepto de “naturaleza”

The eighteenth century saw the birth of the periodical, which targeted a growing educated English upper-middle class. This class was pragmatic, open-minded, but also materialistic and ambitious. “Nature” is one of the most frequently-mentioned topics, though its definition was and is vague. The corpus selected presents the paradox that while nature is praised by nearly all contributors as a perfect machine, the flawless creation of a perfect God, at the same time the manipulation of the natural world carried out by this very class went entirely uncommented on in the texts. El siglo dieciocho vio el nacimiento de la revista, que se dirigía a una clase creciente de personas educadas de clase media y alta en Inglaterra. Esta clase era pragmática, tolerante, pero también materialista y ambiciosa. “La naturaleza” es uno de los temas más frecuentes, aunque su signifi cado era y es imprecisa. El corpus seleccionado presenta la paradoja de que, mientras se elogiaba la naturaleza como una máquina perfecta, la creación de un dios perfecto, por parte de casi todos los autores, al mismo tiempo la manipulación de la naturaleza llevada a cabo precisamente por esta clase pasó inadvertida en los textos considerados

Dynamic Characteristics and Wind-induced Response of a Tall Building

The design of tall buildings requires an accurate understanding of the expected wind loads and the resulting responses. The techniques used to estimate the wind-induced response are subject to uncertainty, which can result in unsatisfactory building performance or an over-designed structure. Altering the structure to rectify unsatisfactory performance can be extremely difficult and prohibitively expensive, while an over-designed structure represents unnecessary cost to the owner. This implies that accurate estimates of wind loads and responses are crucial to tall building design. Two aspects of tall building wind-induced response estimation are investigated: the estimation of natural frequencies and damping ratios; and the understanding of mechanisms causing wind-induced responses. This was primarily conducted via full-scale testing of a tall building. The building used for full-scale measurements is Latitude tower, an office tower located in the Sydney central business district, with a height of 187m above ground and 28m of underground levels. The building has a composite design including a reinforced concrete core, and reinforced concrete floor slabs supported by steel beams spanning between the core and perimeter columns. Outriggers linking the core and perimeter columns, as well as offset outriggers at the facade, are located at mid-height. The full-scale testing was conducted in two parts: vibration testing during construction; and a two year monitoring programme commenced after construction completion. Vibration testing during construction was conducted to determine the natural frequencies and damping ratios as the structure changed. Forced vibration testing and ambient vibration testing techniques were used. The Frequency Domain Decomposition and Stochastic Subspace Identification techniques were used to estimate the natural frequencies and damping ratios from the ambient vibration test outputs. The natural frequencies and damping ratios from the forced and ambient vibration tests differed by less than 5% and 30% respectively. Changes in the fundamental natural frequencies during construction were discussed in conjunction with the structural changes to further the understanding of how changes in the stiffness and mass of a tall building influence the natural frequencies. The measured natural frequencies during the early stages of construction were used to update a finite element model representing the structure at the time of testing. The material properties and floor beams were the primary focus of the model updating. The knowledge gained from partial structure updating was applied to a model of the completed structure, and the natural frequency estimate errors improved from 17% to 7%. The fundamental mode damping ratios measured during construction changed by less than 15% between the first test, conducted when 38% of the tower height was reached, and the final test at construction completion. The wind-induced monitoring programme included the measurement of wind velocities, accelerations, and displacements at the top of the building. The peak events for southerly and westerly wind directions were discussed. It was found that the acceleration response was dominated by the fundamental vibration mode. For southerly winds this corresponded to an along-wind response, but for westerly winds this corresponds to a cross-wind response. The probability distributions of upcrossings for along-wind and cross-wind responses where not significantly different to a Gaussian distribution for both southerly and westerly winds. The slope of the linear least squares fit was greater than two in all cases, which suggested intermittent characteristics were present in the responses. The standard deviation resonant acceleration responses from a high frequency base balance wind tunnel test were within 29% of the measured values