Assessing the improvement capabilities of a generative model 3C-station detector algorithm for the IMS

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Aug 2017

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Abstract
The IMS seismic network produces an abundance of time-series data, posing great challenges for on-line processing and unbiased near real-time analysis. To this end, methods borrowed from the field of machine learning and data mining provide elegant solutions. By adhering to the multivariate statistical framework of Dynamic Bayesian Networks we make use of historical data obtained from the LEB bulletin to train a classifier to capture the intrinsic characteristics of signal and noise patterns appearing in seismic data streams. On a per station basis this yields generative statistical models that essentially summarize and generalize the information implicitly contained in the LEB allowing for classifying future and previously unseen seismic data. About 100 waveform snippets of short duration (4-12 secs) are extracted from 1 week of waveform data for training both the signal and noise classes. On a separate test-set we measure (binary) classification accuracy, sensitivity and specificity. Moreover, when testing against unseen data in time we can confirm seasonal dependency of noise characteristics, calling for an adaptive adjustment of the noise class over time which is implemented in a sequential learning fashion. A major obstacle is however the limited comparability between our purely automatic station-level detector and the combined automatic network associator with subsequent manual inspection approach at the IDC. The improvements over SEL3 and LEB bulletins is therefore difficult to quantify without further effort. To allow for a controlled evaluation we generate a semi-synthetic data set from cutting and pasting real waveform data in between station-specific noise samples.

Author(s): Carsten Riggelsen

THERMAL- INDUCED CRACKING IN A CONCRETE DAM STRUCTURE

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Aug 2017

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Abstract
Shortly after it was completed in 2 006, a castin- place dam exhibited significant cracking in its concrete slabs. An investigation was undertaken which included laboratory studies, field investigations, petrographic examination of concrete cores, and finite element analysis of the early-age thermal and mechanical behavior of the structure. The root cause of cracking was attributed to thermal effects in the slabs early in the age of each slab. Peak tensile stresses from the analysis were determined to be in excess of the modulus of rupture occur through the thickness of the slab approximately 2 0 days from the date of concrete placement. Cores extracted from the structure showed that the cracks extended through the thicknesses of the slabs. Petrographic examination of the cores did not yield evidence of other possible causes of the observed cracking, namely improper curing, improper mixture proportions, or active deterioration mechanisms such as alkali silica reaction. To prevent similar cracking from occurring in similar construction in the future, it is recommended that a thermal management plan be implemented to mitigate the temperature effects that caused the cracking.

Author(s): IC Hodgson, S Pessiki

REFURBISHING JORDANGATE MULTI-STOREY CAR PARK TO OVERCOME STRUCTURAL DEFECTS

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Jul 2017

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A structural appraisal of Jordangate MSCP in Macclesfield, built in the 1 980s, identified chloride penetration within the concrete and recommended treatment using cathodic protection to control the corrosion of the structural steel, together with concrete repairs and waterproofing of the car decks and other associated works. The original worst-case scenario estimates were put forward for budgetary purposes, with more accurate costs dependant on the outcome of further testing and appraisals. Following budget approval, a review of the original structural appraisal report advised that as the effects of chloride penetration had not yet materialized, the use of cathodic protection was not considered to be essential at this stage. The recommendation was that concrete repairs be undertaken and waterproofing be applied to the concrete decks to eliminate water penetration, thereby reducing the risk of chloride attack, followed up by a regular monitoring regime to ensure that conditions had not deteriorated. A number of products from BASF Construction Chemicals were used by Concrete Repairs Limited in carrying out the refurbishment. Numerous deck repairs were needed prior to deck covering and a special CONIDECK? deck membrane strip system tackled the cracking along the joints of the block and beam construction.

Author(s): Bentley

ASSESSMENT OF THE ST. GIUSTA CHURCH IN BAZZANO AFTER THE LAQUILA EARTHQUAKE ON APRIL 6, 2009

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Aug 2017

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Abstract
On April 6th 2 009 an earthquake with a moment magnitude of 6.3 Mw hit the centre of Italy and especially the historical city of LAquila, causing the collapse of many buildings both modern and historic. An overview of the historical cultural heritage showed that the constructions built properly many centuries ago, although the strong seismic events of the past, did not collapse during this last event. It is the case of St. Giusta church in Bazzano, built in the 13 th cent and one of the most beautiful churches of the area. St. Giusta, already hit by different historic seismic events, had serious damages during this last earthquake to the facade, with the collapse of the bell tower, to the columns and to the pillars. The paper will report the first investigation of damages carried out soon after the earthquake, the individuation of the mechanisms of failure and of their causes, the emergency provisional structures realized by the fire brigade and the characterisation of the masonry quality through non destructive tests (flat-jack, sonic, radar and thermography).

Author(s): L Binda, G Cardani, F Maroldi, C Amigoni, F Lorenzoni, C Modena

The conception of conducting a research of the lateral resistance in the track structure during the tamping process

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Jul 2017

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This paper is devoted to the continuation of the research on how to apply a tamping machine in the CWR (Continues Welded Rail) track diagnostic system. The aim of this study is to determine the lateral resistance in the track structure. Lateral resistance exemplifies a fundamental parameter related to the safety issues in railway transport. The danger results from a possibility of loosing stability of the CWR structure, which could be caused by axial (thermal) forces in rails. What is more, the level of lateral resistance has a significant influence on the development of geometrical imperfections process in the track structure. Therefore, it is of great interest to develop effective diagnostic methods that could determine the lateral resistance in exploited railroads. This paper presents the concept of conducting this kind of research during geometrical regulation process in the track structure using a tamping machine. The discussed method aims at recording continuously the track dislocation value as well as the external force which the tamping machine tends to dislocate the structure with. Acquired time-signals enable the estimation of phenomenon based on the lateral resistance distribution in the length of studied routes. The results of conducted experiments have confirmed the thesis about the possibility to use a tamping machine in order to diagnose the lateral resistance in the track structure. Further directions of the research have been formulated in that field around specifying a required set of measurement equipment, along with a method to archive and interpret measured time signals.

Author(s): W Koc, P Chrostowski, S Grulkowski, A. Wilk

Stable coda estimates from P and S codas at regional and near-teleseismic distances

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Jul 2017

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For nearly the past 2 decades, regional shear wave coda has been shown to provide the most stable estimates of the explosion and earthquake source, making its use ideal when station coverage is sparse. As a result, momentmagnitude is determined with unprecedented stability from as few as one station and is being used in a number of explosion monitoring applications. In spite of its success, a significant magnitude bias exists for S-based regional magnitudes such as mb(Lg) and mb (Lg-coda) between explosions and earthquakes when compared to their teleseismic mb(P) counterpart. In this study, we first show preliminary results for regional and nearteleseismc P-coda for both earthquakes and explosions to see if a bias still exists with the teleseismic mb. In addition, there is a point of debate on whether the regional P-coda calibration will remove the effects of the path and upper mantle effects which bias teleseismic mb(P) estimates for some test sites. We find that the P-coda does not exhibit a magnitude bias between earthquakes and explosions, in sharp contrast to S-based magnitudes such as mb(Lg) when compared to the teleseismic mb(P). We plan to give a summary of regional coda research and specifically address our recent P-coda findings.

Author(s): Kevin Mayeda

MODELLING DETERIORATION OF RC BRIDGES USING THE FACTOR METHOD

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Jul 2017

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This paper highlights the importance of the model of the deterioration process of the concrete bridges and its significance in the bridge management and the development of the factor method. The most common types of damages caused by the deterioration included minor cracking, major cracking, spalling and service failure and the cost ranged from millions to billions. The rate of deterioration of Foot Bridge and over bridge and their members were examined. The rate was higher in Footbridge as compared to overbridges. The main reasons were use of the structure, construction type and exposure conditions. Various types of predictive models mainly deterministic and probabilistic approach were reviewed which includes Markov chain model, regression model & Factor method. The analysis suggested the factor method was most comprehensive among others. The factors considered in modelling were of two approaches: deterministic and probabilistic.

Author(s): A Abu-Tair, J Bai, D Tann, C McParland

Soccoro Islands IMS T-stations record the modification of the strain field due to the passage of

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Jul 2017

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The IMS infrastructure can be used effectively in civil applications, for instance to augment the capacity of organizations charged with warning the authorities about dangerous natural events, such as earthquakes and tsunamis. Relevant IMS data is already forwarded to regional tsunami centres under agreement with CTBTO. This includes seismic IMS stations for accelerated tsunamigenic event detection and hydroacoustic stations for the recording of the passage of the tsunami. In this work, we suggest that data from coastal and island T-stations is also useful for direct detection of the passage of the tsunami. The possibility of observing the passage of tsunamis on these coastal seismic stations was confirmed in the Pacific Ocean for the tsunamigenic Maule, Chile earthquake of 27 February 2010 on the horizontal components of two broad-band seismometers used as hydroacoustic T-station located on Socorro Island, Mexico. Similar observations of long period effects of the passage of tsunami on the horizontal components of near-shore seismometers had been made previously and tentatively explained as long-period components of the propagation modes of gravity waves, where the presence of the island is ignored. Polarization and amplitude analysis of the longperiod arrivals observed at Socorro allows an alternate physical explanation and our preferred explanation is that the islands strain field is responding elastically to the load of the very long wavelength tsunami on the walls of the island. This hypothesis is confirmed by analysis of the passage at Socorro of another tsunami from the September 29th, 2009, Samoa earthquake.

Author(s): Alexander Poplavskiy, Ronan Le Bras

Structural elucidation of carboxylic acids in supercomplex petroleum mixtures for the determination of oil quality and toxicity

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Jun 2017

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Crude oil is the worlds most widely used energy resource and with an ever-growing demand for the finite supply, petroleum companies are now extracting less accessible reserves holding lower quality crude oil. However modern exploitation has led to new concerns over the toxicity of increasing extraction waste and refinery problems (e.g. pipeline deposits). One class of compounds associated with causing some toxicity in process waters and corrosion in pipelines, is the carboxylic or so-called naphthenic acids (NA). Early research identified NA as acyclic and monocyclic structures, however recent interest in acid-rich crudes has led to the identification of bi- and tricyclic, aromatic, steroidal monocarboxylic acids and long chain acids with multiple acid moieties (e.g. C80-tetra acids), principally by improved gas chromatographic methods. The current research attempts to identify NA from both petroleum and oil sands but in this case by first converting NA to their hydrocarbon equivalents using a three-step conversion whilst maintaining the integrity of the skeletal carbon structure. This should result in improved chromatography due to the reduced polarity of the analytes, enhancing structural elucidation. So far, in the initial 3 months, three known model bicyclic acids have been reduced to their corresponding alcohols. Reactants and products have been characterised by FT-IR spectroscopy, GC-FID and GC-MS of derivatives. Subsequent work will involve dehydration to the alkenes and catalytic hydrogenation to the alkanes. Results from the model compounds will act as a preliminary indication of the success of the synthetic conversion for unknown and more complex petroleum mixtures. Successful identification of the NA structures present in petroleum will help to focus studies on the quality and processing of less favourable crude oils with the overall aim of making the extraction of such crudes more efficient and cost-effective, with less environmental impact.

Author(s): Mike Wilde, C. Anthony Lewis, Steve Rowland

SENSING SLEEPER FOR DYNAMIC PRESSURE MEASUREMENT ON A SLEEPER BOTTOM INDUCED BY RUNNING TRAINS

Engineering Sciences and Technology Journal (ESTJ), Volume 2, Jun 2017

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This paper describes a newly developed measurement technique of the dynamic pressure distribution on a sleeper bottom induced by running trains with high frequency of up to several thousand Hertz using a special sensing sleeper equipped with ultra-thin-type impact force sensors. The sensing unit comprises a PC3-type mono-block concrete sleeper fitted with a large number of sensors. Attached to the sleepers whole undersurface is a solid mass made up of 75 thin impact force sensors (80 mm ? 80 mm ? 2 0 mm). Each impact force sensor has a main body and cover members. The main body, made from piezoelectric film (PVDF) and silicone rubber, has solid cover plates on both surfaces of the main body. The cover plates transmit impact force to the main body through multi-contact loading, which prevents breakage of the sensor itself from a running trains impact loads. The sleeper sensory performance was tested in a fullscale field experiment performed on a railway line. The results confirmed that the newly developed techniques are beneficial for measuring dynamic interaction within the boundary layer between a sleeper and an assemblage of ballast grains.

Author(s): A Aikawa, F Urakawa, A Kono, A. Namura