456 research outputs found
IEC 61850 tripping circuit monitor with IEEE 1588 synchronization
No full textY. Liu, R. Zivanovic and S. Al-Saraw
Licenser under cover: The Genitive of Negation in Slovenian
No full textIn some languages there exist syntactic environments in which noun phrases of negated sentences do not take nominative or accusative case as their counterparts from the parallel affirmative sentences do. Instead, they are inflected for the genitive, usually called the genitive of negation. The article (i) reconsiders the list of these environments; (ii) describes an observation whereby the genitive of negation on the subject cancels the subject-verb agreement, triggering the default morphosyntactic form of the (auxiliary) verb; (iii) compares the distribution of the genitive of negation to the distribution of the negative-numeral nič “nothing”; and (iv) argues for the hypothesis that the genitive of negation is licensed by the covert version of the n-numeral nič “nothing”
FE modelling and updating of unique fink truss footbridge
No full textRecent improvement of mechanical characteristics of structural materials and fast development of the
finite element (FE) based computational structural analysis are resulting in innovative solutions in
footbridge design. When doing research into dynamic analysis of these structures, their dynamic
properties are required and are usually obtained from an FE model. However, because of structural
complexity, the FE modelling of footbridges is often prone to errors due to modelling uncertainty. The
best and quite often the only way to evaluate the reliability of the FE modelling is to involve modal testing
and FE model updating of footbridge structure with the aim to match test results. Using this approach, a
complex and rather unique Fink truss structure of Royal Victoria Dock Bridge in London was analysed.
Eleven measured modes of vibration were identified via an ambient vibration survey and then compared
with their counterparts from an initial FE model developed by best engineering judgment. In this initial FE
model the maximum difference between two paired natural frequencies was 29%. In a subsequent
updating exercise it was found that uncertainties in main beam and crosshead geometry, as well as the
inherent simplicity of the fully symmetric FE model, were the main source of the modelling error
Vibration performance of a lightweight FRP footbridge under human dynamic excitation
No full textFibre-reinforced polymer (FRP) composites are increasingly used as main load bearing materials in design of pedestrian bridges. The FRP footbridges are typically characterised by high strength, and relatively low mass and stiffness. These properties could lead to excessive vibration response under human-induced dynamic loading. This paper studies dynamic performance of a 19.8 m long, simply supported, FRP footbridge exposed to walking and jogging. Moreover, the vibration response of this bridge is compared and critically evaluated against the response of an equivalent, in terms of natural frequency and span length, composite steel-concrete structure. The main factors that drive the vibration performance of the FRP structure are discussed and some recommendations for vibration serviceability checks are made
The Genitive of negation in Slovenian
No full textIn some languages there exist syntactic environments in which noun phrases of negated sentences do not take nominative or accusative case as their counterparts from the parallel affirmative sentences do. Instead, they are inflected for the genitive, usually called the genitive of negation. The article (i) reconsiders the list of these environments; (ii) describes an observation whereby the genitive of negation on the subject cancels the subject-verb agreement, triggering the default morphosyntactic form of the (auxiliary) verb; (iii) compares the distribution of the genitive of negation to the distribution of the negative-numeral nič “nothing”; and (iv) argues for the hypothesis that the genitive of negation is licensed by the covert version of the n-numeral nič “nothing”
Quality control of slope-intercept measurements of glomerular filtration rate using single-sample estimates
No full textObjectives: Measurement of glomerular filtration rate (GFR) using the slope-intercept technique determines the plasma clearance curve by fitting a straight line to the logarithm of sample count rate. When two samples are used there is no check on the validity of curve fitting. GFR may also be estimated from single-sample concentrations. This study describes a method of quality control for the two-sample technique using the agreement between the one-sample and two-sample estimates.Methods: GFR measurements using 99mTc-DTPA were performed on 225 adults and 100 children using two samples taken between 2 h and 4 h post-injection. The two-sample values obtained using the British Nuclear Medicine Guidelines slope-intercept technique were compared to one-sample estimates obtained using a new general equation. Equations describing the variation of GFR error with GFR value were defined. These were used to determine action levels giving the limits of expected agreement between slope-intercept and single-sample values. The use of these action levels for quality control was demonstrated in a further 120 GFR measurements.Results: The variation of single-sample error estimate with GFR depended both on the time of sample and body surface area. For specific sample groups, the error variation with GFR could be approximated using a truncated quadratic equation. Four studies were identified as failing quality control in the dataset used to define the error equations. Two studies failed in the test dataset.Conclusions: One-sample equations give reliable estimates of GFR, which may be used for quality control of slope-intercept GFR assessment
A general equation for estimating glomerular filtration rate from a single plasma sample
No full textObjectives: Glomerular filtration rate (GFR) may be estimated from a single plasma sample measurement using empirical equations. This method forms the basis of international guidelines on GFR measurement. New guidelines have recently been recommended by the British Nuclear Medicine Society (BNMS). These use the slope-intercept technique in which several samples are obtained. Quality control of measurement may be achieved by comparison with the individual single-sample values. This paper compares international guideline single-sample estimates of GFR with the new BNMS method and derives an improved general single-sample equation.Methods: GFR measurements using 99mTc-DTPA were performed on 180 adults and 100 children using samples at approximately 2 h and 3 h and a further 45 adults with samples at 2, 3 and 4 h. The two-sample values obtained using the BNMS guideline method were compared to one-sample estimates obtained using (1) international guidelines and (2) a new equation derived from the data. The new equation was evaluated in a further 145 subjects.Results: The international guidelines technique had systematic differences between the one-sample and two-sample estimates of GFR. The new equation had minimal systematic error and reduced random error (standard error of the estimate 4.5 ml [middle dot] min-1 per 1.73 m2).Conclusions: There were significant differences between GFR values obtained using the international guidelines single-sample method and the slope-intercept method described in the BNMS guidelines. The new equation described in this paper gave considerably improved agreement and is recommended if single-sample estimates are to be used as quality control for BNMS guideline measurements
Effect of group walking traffic on dynamic properties of pedestrian structures
No full textThe increasing number of reported vibration serviceability problems in newly built pedestrian structures, such as footbridges and floors, under walking load has attracted considerable attention in the civil engineering community over the past two decades. The key design challenges are: the inter- and intra-subject variability of walking people, the unknown mechanisms of their interaction with the vibrating walking surfaces and the synchronisation between individuals in a group. Ignoring all or some of these factors makes the current design methods an inconsistent approximation of reality. This often leads to considerable over- or under-estimation of the structural response, yielding an unreliable assessment of vibration performance
Statistical characterisation of parameters defining human walking as observed on an indoor passerelle
No full textIncreased slenderness of footbridge structures in the last few decades has led to an
increasing number of vibration serviceability problems under human induced dynamic load,
such as walking. These problems are typically related to increased discomfort of footbridge users
due to perceptible vibrations during footbridge crossing. The current codes of practice dealing
with the vibration serviceability of footbridges often fail to assess reliably the vibration level
induced by humans. This is because they model the load induced by pedestrians by considering
only an ‘average’ walker. However, because of natural diversity in human population, so called
inter-subject variability, it is necessary to model the walking force in a probabilistic way taking
into account this type of variability. To do this, a large database of parameters (such as walking
frequency, step length and weight) describing walking force induced by different individuals is
required. Currently, only limited amount of data to populate this database is available. To generate
more data of this kind, pedestrian traffic on an indoor passerelle inside a University campus
in Sheffield was monitored using video cameras for 6.5 hours. The data that characterise
human walking (such as walking frequency, step length and arrival time) were collected and
analysed statistically. Based on this, the probability density functions for the parameters analysed
were constructed. The results of this study could be used when defining a badly needed
probabilistic force models for vibration serviceability assessment of indoor passerelles of this
kind
Guidelines for the measurement of glomerular filtration rate using plasma sampling
No full textThese guidelines have been adopted by the British Nuclear Medicine Society
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