Parallel to the technological developments, methods of defining locational data are changing. Laser scanners bring new advantages to engineering measurements and geodesy. Terrestrial laser scanners, ...which have previously been used in map engineering, have become an alternative method of measurement, especially for terrestrial applications. A common characteristic of deformation measurements is the requirement to measure the location of sufficient reference and object points established on the monitored structure. The number of reference and object points is limited when using classical methods, but not when using a laser scanner. Due to the limitations of classical geodetic survey methods, such as difficulty of application, high costs and low production speed, the present study applied ground laser scanners to deformation monitoring. A two-dimensional (2D) deformation survey was made of a concrete frame placed on a loading wall. Cartesian coordinates, derived from survey and evaluations, were converted into a standard coordinate system using the Molodensky–Badekas 3D similarity transformation. Student’s
t
test has been used to determine whether it was significant with the difference of coordinates or not. The deformation amounts and directions obtained from the electronic tachymeter and ground laser scanners were found to be very similar.
Among the many activities carried out for the protection of monuments, geodetic measurements are primarily used for the inventory of objects and the study of their movements and deformations. In ...Jaroslaw at the Benedictine Abbey, the framework of the Scientific Association of Surveyors AGH, systematic surveying measurements of the walls and the verticality of towers of the church have been conducted since 2006. Thanks to years of measurements, the researchers were able to determine the movements of church towers and prevent their further swinging movements. In the paper, the authors show the course of the study and analyze the results. The surveying sampling was the basis for applying for EU aid which after the meeting the relevant requirements has been awarded in the amount of EUR 1.25 million to save the object.
For some time past, terrestrial laser scanning has been adopted as one of the data acquisition techniques for e.g. deformation measurements, documentation of historical monuments and civil ...engineering projects. Using terrestrial laser scanning, millions of 3D points can be obtained with a high accuracy in a time span of minutes or even seconds depending on the type of laser scanner. However, processing the data still remains a time consuming process. As a result, total station measurements are often preferred over laser scanning for high frequency deformation measurements when time for data processing is limited. In the research at hand, the applicability of terrestrial laser scanning in time critical situations was assessed based on the case of a recent monitoring project on a sewage purification plant. Deformations had to be assessed twice a day in order to prevent accidents from happening. The total station measurements were executed and processed by a specialized company.
Standard fracture mechanics tests were carried out on two different types of aluminium foam, ALPORAS
® foams and ALULIGHT
® foams, with a variety of densities. Standard fracture toughness tests on ...compact tension (CT) specimens with widths from 50 mm to 300 mm and in situ tests in the scanning electron microscope were performed. Fracture toughness values in terms of the critical stress intensity factor,
K
IC, the critical
J-integral,
J
IC, and the critical crack-tip opening displacement, COD
5,i, were determined. To identify the fracture process, local deformation measurements were performed on the foam surfaces with a digital image processing system.
From the deformation measurements it is evident that the deformation is strongly localised on different length scales. A relatively large fracture process zone, 6–8 cells in height, is developed, where only few of them are heavily deformed. On the cell wall level the deformation is again strongly localised to the thinnest parts of the cell wall, where cracks initiate and propagate. The crack propagates through the foam, building many secondary cracks and crack bridges. The comparison of
K vs. Δ
a (crack extension),
J vs. Δ
a and COD vs. Δ
a with the current fracture processes at the crack tip and the load–displacement response reveals that COD gives the most reliable measured values to characterise the fracture toughness.
For determination of three-dimensional movements of points from repeated surveying and for obtaining real values of displacements, a convenient testing is needed as well. Besides the standard ...mathematical ways in this field, which is a new geometrical method by relative confidence ellipsoids can be used, is presented in this paper.
A Neural Network Method For The BFS Extraction Krivosheev, A.I.; Konstantinov, Yu.A.; Krishtop, V.V. ...
2022 International Conference Laser Optics (ICLO),
2022-June-20
Conference Proceeding
We present a method for increasing the accuracy of determining the Brillouin frequency shift in a fiber strain sensor. A neural network which using the results obtained from other methods as input ...data and the parameters of the system is applied. The result is an additional 10% accuracy increasing, which is significant given that existing methods have already reached their limit and work at low SNR values (about 5 dB).
Repeated high quality geodetic observations allow the estimation of the free surface velocity field for a region. Usually, a yearly secular rate is estimated, while the possible episodic motion ...(seismic slip) due to an earthquake is evaluated via inversion of the geodetic data. The episodic motion influence is subtracted from the total field. The actual region and the respective geodetic observations affected by the seismic event are often assessed by rather vague criteria.
This paper deals with an attempt to estimate simultaneously the secular and the episodic two-dimensional crustal motion for a region by means of repeated GPS observations of a geodetic network, carried out for a number of epochs.
The model is applied to the Gulf of Corinth available GPS data, spanning a time interval of more than a decade, and the results are discussed.
Exploitation of a Spider Silk based Sensing Element Trigona, Carlo; Cunsolo, Caterina; Luca Cardillo, Giuseppe Di ...
2022 IEEE International Instrumentation and Measurement Technology Conference (I2MTC),
2022-May-16
Conference Proceeding
In this paper, a green sensing element based on a spider silk used as self-generating piezo-electric layer is proposed. The sensor has been realized by using a three-layer structure with the spider ...silk covered by using two layers of aluminum. The sensing element is mounted at the anchor of a cantilever beam and will be used to measure the deformation through its capabilities to generate voltage when deformed. The paper includes the modeling and the study of the piezoelectric properties of the green transducer. Furthermore, experimental results will demonstrate the suitability of the proposed device.
Masonry component products are increasingly made industrially with reduced variation in mechanical properties. The joint is the only part of the masonry that is affected by manual action and so the ...load bearing capacity is not only determined by the quality of the bricks and mortar used but moreover by the way the masonry has been built and cured. As a result, it may be expected that the largest material variations are at the brick-mortar interfaces. This has been observed as irregular interface bonding with a bonded central area surrounded by fissures. As a consequence of the final shape of the joint, forces concentrate in the central part of the joint and strain variations occur near fissure tips which result in spalling of bricks in experiments. This paper demonstrates the need for detailed deformational measurements in the brick-mortar interface region. To overcome the limitations with traditional measuring instruments, a refined methodology based on the laser speckle technique is introduced in a companion paper Canadian Journal of Civil Engineering,
34
(11), 1467 (2007) by the authors of this paper.
Improvements of a method for measurement of continuous displacements and deformations with digital phase shifting speckle pattern interferometry are presented. The method is based on an algorithm ...that, with the knowledge of the initial phase, only needs one image at a time to evaluate continuos phase changes due to object deformations. In the improved method, the initial random phase of the speckle pattern is evaluated using a number of phase-shifted images before the deformation under study. This is used for increasing the accuracy of the initial phase estimation and reducing influences from image noise and other measurement disturbances. The phase-shifted speckle patterns are used as references for comparison with the speckle patterns of the deformed object, thereby increasing the reliability and accuracy of the phase estimations of the deformed patterns. The technique can be used for measuring deformations such as transients and other dynamic events, heat expansion as well as other phenomena where it is difficult to accomplish phase shifting during deformation.
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