169,979 research outputs found
A Hybrid Maintenance Policy for a Deteriorating Unit in the Presence of Random Effect and Measurement Error
No full textInternational audienc
Misspecification Analysis of a Gamma- with an Inverse Gaussian-Based Perturbed Degradation Model by Using a New Expectation Maximization Particle Filter Algorithm
No full textInternational audienc
Practical issues in sequential dynamic analysis of simple inelastic oscillators
No full textThe analytical evaluation of seismic structural behavior under repeated earthquake shocks,
that can potentially cause failure due to damage accumulation, often makes recourse to
sequential dynamic analysis of a numerical model. One such dynamic analysis strategy is the
so-called, back-to-back incremental dynamic analysis (B2B-IDA), whereupon one
accelerogram is scaled in such a way as to bring the structure to a specific conventional
damage state and is then followed by a second accelerogram which is scaled in amplitude
over a wide range of shaking intensity levels, forcing structural response to span the entire
range of possible damage states. The need to effectively capture record-to-record variability
of response for seismic reliability analyses, means that B2B-IDA is typically applied using a
multitude of ground motions representing both the first damaging shock as well as the second
shock in the sequence that affects the damaged structure. The present study uses a variety of
such SDOF inelastic structures to explore a series of practical issues that arise in running
B2B-IDA and post-processing the results. This investigation uses the DYANAS graphical
user interface, which was previously developed with the contribution of the authors as a tool
that can be also used for streamlining this type of analysis. The first issue that is addressed in
this study is the number of records used to represent both the first and the subsequent seismic
shock affecting the structure. Previous research has shown that the statistical inference
concept of estimation uncertainty can be used as a tool to quantify the effect of the record
sample size, used in single-event dynamic analysis, on the accuracy of the results obtained.
The present article picks up on that methodology and seeks to extend it in the context of B2B-
IDA. A second practical issue considered is the implementation of a hunt-and-fill algorithm
in order to minimize the number of runs needed to efficiently represent a single B2B-IDA
curve. Such an algorithm can allow the rapid transformation of B2B-IDA curves from one IM
to another when combined with appropriate interpolation techniques. Finally, this article
briefly addresses updates in the DYANAS software that were explicitly implemented to
facilitate the extraction of results from B2B-IDA for the purpose of obtaining so-called state-
dependent fragility functions, that is models providing the conditional probability of a
structure transitioning from one damage state to another, given shaking intensity
State-dependent fragility functions for RC frames subjected to tsunami triggered by earthquakes
No full textItalian Seismic Risk Maps Based on Code-Compliant Design
No full textThis paper discusses the Italian seismic risk assuming that the existing buildings portfolio is substituted by new code-conforming
structures. The seismic risk is quantified, at municipality scale, via the evaluation of failure rate per building class. This requires: (i) the
probability that the structures fail for a given ground motion intensity value, that is, the fragility functions and (ii) the hazard curves
resulting from probabilistic seismic hazard analyses. The adopted fragility functions come from the Italian research project RINTC –
Rischio Implicito delle Strutture progettate secondo le NTC, in which a large set of buildings was designed for three sites representative
of different seismicity. Thus, the Italian municipalities were divided in three seismic classes and it was assumed that fragility functions
from RINTC are representative of new design (residential) structures, according to a replacement criterion that was established to associate
the structural typologies of the existing buildings to those considered in the project. The failure rates per building typology were computed
first, combining the structural fragility functions and the computed hazard curves. Then, the failure rates were averaged over the building
typologies and the percentages of soil conditions characterizing each municipality. The results, presented in the form of maps, show that
the fragility of masonry structures have the main impact on the maps, which are also affected by the identification of the hazard and soil
classes of the sites
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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