Search results for "testing."
showing 10 items of 1654 documents
PERFORMANCE ASSESSMENT IN SCIENCE NATIONAL LEVEL DIAGNOSTIC TESTS
2018
National Centre of Education of the Republic of Latvia in 2016 lunched national project of the renewal of the curriculum for education funded by the European Social Fund. One of the key priorities of successful implementation of the new education curriculum is transforming national level assessment system.Assessment system measuring student performance must meet different requirements from the traditional measurement instrument assessing content knowledge.Analysing 2017 national level science assessment diagnostic tests of 15-16 years old students, it is impossible to discriminate student different level of performance. Student, demonstrating singly stored pieces of knowledge, integrating p…
Testing mechanical characteristics of chestnut stakes used in bed sills for stream restoration
2017
Using of wood elements for constructing bed sills in Mediterranean streams, where the banks are not protected by tree vegetation, needs an evaluation of biological and mechanical characteristics for evaluating both the wood durability and the effectiveness of the stream restoration project. Very few studies have dealt both with the decay of mechanical characteristics of wood elements employed for stream restoration works and with the changes over time of physical and chemical wood characters. In this paper, for a wood and stone bed sill located in a stream having no shaded banks, the changes of physical and chemical characters detected after 12, 18, 24, 30, 36, 42 and 48 months on chestnut …
Eddy current flaw detection with neural network applications
2005
Abstract Eddy current inspection is a fast and effective method for detecting and sizing most of the flaws in conducting materials. The inverse problem solution, i.e., inferencing about possible defect, based on the measurement signal from the eddy current probe, is a difficult task. In this paper an implementation of artificial neural networks for multi-frequency eddy current testing on conducting layers (aluminum, copper) and ferrous tubes has been presented.
Robotic path planning for non-destructive testing of complex shaped surfaces
2015
The requirement to increase inspection speeds for non-destructive testing (NDT) of composite aerospace parts is common to many manufacturers. The prevalence of complex curved surfaces in the industry provides significant motivation for the use of 6 axis robots for deployment of NDT probes in these inspections. A new system for robot deployed ultrasonic inspection of composite aerospace components is presented. The key novelty of the approach is through the accommodation of flexible robotic trajectory planning, coordinated with the NDT data acquisition. Using a flexible approach in MATLAB, the authors have developed a high level custom toolbox that utilizes external control of an industrial …
Dynamic characterization for the dielectric electroactive polymer fundamental sheet
2012
Published version of an article published in the journal: International Journal of Advanced Manufacturing Technology. Also available from the publisher at: http://dx.doi.org/10.1007/s00170-012-4423-6 A study into the appropriateness of characterizing the dynamics of the dielectric electroactive polymer (DEAP) fundamental sheet has been performed. Whereby a model describing the dynamics of the DEAP fundamental sheet is developed, parameters of the models are determined using experimental/simulation results, and verification has been conducted to determine the precision of the dynamic model. The precision for the DEAP sheet-obtained dynamic model could not be verified unless some parameters c…
Compressive sensing for direct time of flight estimation in ultrasound-based NDT
2017
This paper presents an approach for estimation of ultrasonic time-of-flight (TOF) within a Non Destructive Testing (NDT) and Structural Health Monitoring (SHM) context. The presented method leverages recent advances in the field of Compressive Sensing (CS), which makes use of sparsity in a transform domain of a signal in order to reduce the number of samples required to store it. CS achieves this through a two key ideas: random matrix projections, and l1-penalised linear regression. In this case, sparsity arises from the observation that in a pulse-echo ultrasound test, the number of echoes is relatively small compared to the number of measurement points in a waveform. This sparsity is evid…
Effects of circular openings on the compressive behaviour of R.C. columns
2014
Core-drilling technique is nowadays always more frequently performed in existing reinforced concrete (RC) structures in order to investigate on the mechanical properties of concrete and for structural health monitoring purposes. Even if the engineering practice discourages to drill columns, this can be often unavoidable. In this last case the presence of the circular opening influences the compressive behavior of the column in terms of load-carrying capacity and axial deformability. The goal of this investigation was the experimental evaluation of the effects induced by circular openings on the behavior of RC columns. Twenty-four reinforced and plain concrete prisms in presence of circular …
Experimental investigation on PLC signal crossing of power transformers
2014
In this work the use of PLC in MV-LV networks is investigated, by means of experimental tests in the case of a two-ways MV/LV communication between two secondary substations. The two substations are connected by a MV overhead power line. Moreover each substation has a by-pass connection at MV bus-bars and a MV/LV power transformer. A ST7580 transceiver is used to inject the communication signal. The transceiver is embedded in a new interface device developed by the authors. In the paper the communication issues are introduced and some experimental tests are presented and discussed. Such tests have been carried out in the presence of voltage net, i.e. 24 kV, with the aim to verify the possib…
Experimental Study of Cross-flow Micro-turbines for Aqueduct Energy Recovery
2014
An important component of the management cost of aqueducts is given by the energy costs. Part of these costs can be recovered by transforming some of the many existing energy dissipations in electric energy by means of economic turbines. In this study an experimental work has been carried out: 1) to test the performance of an economic Cross-Flow turbine which maintains high efficiency within a large range of water discharges, and 2) to validate a new approximated formula relating main inlet velocity to inlet pressure. It is proved that the proposed formula, according to some simplifying assumption, exactly links inlet velocity to inlet pressure according to any possible geometry of the Cros…
Variance-based sensitivity analysis for wastewater treatment plant modelling.
2014
Global sensitivity analysis (GSA) is a valuable tool to support the use of mathematical models that characterise technical or natural systems. In the field of wastewater modelling, most of the recent applications of GSA use either regression-based methods, which require close to linear relationships between the model outputs and model factors, or screening methods, which only yield qualitative results. However, due to the characteristics of membrane bioreactors (MBR) (non-linear kinetics, complexity, etc.) there is an interest to adequately quantify the effects of non-linearity and interactions. This can be achieved with variance-based sensitivity analysis methods. In this paper, the Extend…