Internal Damage Analysis of Braided Composites Embedded in Carbon Nanotube Yarn

Carbon nanotube (CNT) yarn sensors were embedded in 3D braided composites in the form of arrays to detect the internal damage of specimens and study the internal damage monitoring of the 3D braided composites. The signals collected by the sensor array of CNT yarn were preprocessed using the dynamic wavelet threshold algorithm. The exact position of the damage was calculated based on the main features of the resistance signal matrix, which was calculated using the quadratic matrix singular value. The results show that the internal damage localization of the specimens was consistent with the actual damage. The localizations in this study can provide a basis for enhancing the structural health monitoring of smart 3D braided composites.

Bearing Remaining Useful Life Prediction Based on a Scaled Health Indicator and a LSTM Model with Attention Mechanism

Rotor systems are of considerable importance in most modern industrial machinery, and the evaluation of the working conditions and longevity of their core component—the rolling bearing—has gained considerable research interest. In this study, a scale-normalized bearing health indicator based on the improved phase space warping (PSW) and hidden Markov model regression was established. This indicator was then used as the input for the encoder–decoder LSTM neural network with an attention mechanism to predict the rolling bearing RUL. Experiments show that compared with traditional health indicators such as kurtosis and root mean square (RMS), this scale-normalized bearing health indicator directly indicates the actual damage degree of the bearing, thereby enabling the LSTM model to predict RUL of the bearing more accurately.

Fold cracking of coated papers: investigation on automated computer-aided visual assessment method

In this paper, white pixel percentage (WPP) value, as an overall measure of fold crack damages, has been analysed with respect to selected parameters of sample preparation and digitalization process, as well as the results of residual tensile strength. The WPP values were derived by an automated image processing algorithm, developed earlier, based on extensive comparative analysis of the existing computer-aided methods. Results indicate that WPP values correlate well with the extent of fold cracks on the coated samples, as far as the used parameters of sample preparation and digitalization are concerned. In the case of correlation with residual tensile strength, results for samples folded in cross direction revealed that the extent of the visually registered fold cracks agree well with the actual damage, while for samples folded in machine direction, the overall strength losses weren’t alarming, although the fold cracks were detected correctly. In addition, results pointed out that the simplest sample placement position (inner angle of 180°) is not applicable for realistic sample representation. Furthermore, scanners could provide a superior image quality in lab conditions, but for industry application, a camera-based solution would be more purposeful, while micrographs are more suitable for traditional visual analysis.

Issues in Tsunami Countermeasures from the Viewpoint of Geotechnical Engineering

The 2011 off the Pacific coast of Tohoku Earthquake, with its epicenter off the Sanriku coast, measured the moment magnitude of 9.0, had a maximum seismic intensity of 7 in the northern part of Miyagi Prefecture, and impacted an area of 450 km. Consequently, a variety of unprecedented problems were made apparent. In particular, the human and property damage wrecked by the ensuing tsunami triggered our response for earthquake and tsunami resistance. In addition to conventional issues, such as earthquake resistance of buildings, disruption of lifelines, liquefaction of residential land and soil structures, and tsunami damage in coastal areas, there were new challenges, such as prolongation of earthquake disaster waste treatment. During the 10 years since the 2011 earthquake, tsunami countermeasures have been reexamined, and based on the concept of multiple protections, both tangible and intangible countermeasures have been advanced. This article addresses technical problems related to complex disasters, and includes the example of actual damage to a river levee in the Iwate Prefecture and the case of a building overturned by tsunami in Onagawa City, Miyagi Prefecture. It also discusses liquefaction caused by earthquakes and lists the points to be considered when selecting tsunami evacuation buildings to tackle future tsunami disasters.

A Synthesized Study Based on Machine Learning Approaches for Rapid Classifying Earthquake Damage Grades to RC Buildings

A vast number of existing buildings were constructed before the development and enforcement of seismic design codes, which run into the risk of being severely damaged under the action of seismic excitations. This poses not only a threat to the life of people but also affects the socio-economic stability in the affected area. Therefore, it is necessary to assess such buildings’ present vulnerability to make an educated decision regarding risk mitigation by seismic strengthening techniques such as retrofitting. However, it is economically and timely manner not feasible to inspect, repair, and augment every old building on an urban scale. As a result, a reliable rapid screening methods, namely Rapid Visual Screening (RVS), have garnered increasing interest among researchers and decision-makers alike. In this study, the effectiveness of five different Machine Learning (ML) techniques in vulnerability prediction applications have been investigated. The damage data of four different earthquakes from Ecuador, Haiti, Nepal, and South Korea, have been utilized to train and test the developed models. Eight performance modifiers have been implemented as variables with a supervised ML. The investigations on this paper illustrate that the assessed vulnerability classes by ML techniques were very close to the actual damage levels observed in the buildings.

18. Trespass to land and nuisance

This chapter examines torts of trespass to land and nuisance. Trespass to land is concerned with direct harm, and the tort’s primary importance is the protection of property rights. Harm in this context does not necessarily mean actual damage to the land concerned. The harm lies in the fact that land owned by one party has been unjustifiably interfered with by another. Private nuisance deals with indirect and unreasonable interferences to land, including what might be called consequential interferences resulting from a direct action. Private nuisance regulates relationships and conflicts between neighbours, defining their mutual rights and obligations with respect to land use. Many aspects of the law of nuisance, including determining whether an injunction or damages is the appropriate remedy, were clarified by the Supreme Court in Coventry v Lawrence [2014].

Cartographic research method of developing recommendations on prevention of water-related emergencies

In the paper, the use of cartographic research method for the analysis and generalization of materials describing extreme events associated with rarely recurring high water and flooding in river basins of the Upper Ob is proposed. Basing on statistical data obtained from municipalities of the adjacent regions (Altai Krai, Republic of Altai, Kemerovo, Novosibirsk and Tomsk oblasts), including the information provided by territorial bodies of the RF Emergency Situations Ministry, we created a database for assessing actual and probable damage to population and economy of the study territories. Actual damage is generalized and analyzed in the context of river basins and municipalities of the entities, i.e. subjects of the Russian Federation. In order to assess probable damage, cartographic sources, including open data from the Internet as well as modern software tools were involved. The estimation of probable damage to population and economic objects was performed by the example of settlements (including those suffered from extreme flooding of 2014) located in the Charysh basin (Altai Krai). For that GIS projects and a series of damage evaluation maps were created. River basins of the Upper Ob regions were ranked according to recurrence frequency of extreme events and the extent of actual damage to population and economy there in 2004–2018. On the basis of these results, recommendations to prevent emergencies caused by the negative impact of water were developed.

Uncertainties Consideration in Empirical Frequency Response Function Data for Damage Identification Based On Artificial Neural Network

The modern application of frequency response function (FRF) with artificial neural networks (ANN) has become one of the leading methods in vibration-based damage detection approach. However, since full-size empirically obtained FRF data is used as ANN input, a broad composition ANN input layer series would occur. Consequently, principal component analysis (PCA) is adopted to compress the FRF data magnitude. Despite this, PCA alone is unable to select the important FRF data features effectively, due to the exceedingly FRF data size in addition with existing uncertainties. Therefore, this study proposed the merger of a non-probabilistic analysis and ANN approach with PCA by considering the uncertainties effect and the inefficiency of using empirical FRF data. The empirical FRF data is obtained from a steel truss bridge structure. The results show that the PoDE values above 95% are measured at the particular executed damage locations and the DMI values show the damage severity at the actual damage locations. Overall, the results show that the proposed method is capable in considering the uncertainties effect on the empirical FRF data for structural damage identification.

PERBANDINGAN KERUSAKAN AKTUAL DAN PRAKIRAAN PADA BANGUNAN TEMBOK TANPA PERKUATAN AKIBAT GEMPA

On April 18, 2018, an earthquake hit Banjarnegara Regency, Central Java. The earthquake was measured M4.4 at a depth of 4 km and caused damages to buildings in several villages within Kalibening District. Predicting the future earthquake events is difficult. However, it is possible to estimate the potential damage caused by an earthquake event. FEMA has developed a methodology called HAZUS to estimate the potential loss and damage caused by earthquakes. This study compared the level of actual damage to buildings subjected to the 2018 Banjarnegara earthquake with the estimated damage to buildings obtained using HAZUS. The real damage is obtained from the field survey while the estimated damage is obtained from the HAZUS modeling. The object of this research is the unreinforced masonry low-rise buildings (URML) in Kasinoman Village, one of the villages that suffered the most subjected to the 2018 Banjarnegara Earthquake. The result of this study indicates the actual damage has a higher mean damage ratio (20,40 %) compared to the estimated damage (11.66%). HAZUS is developed according to the performance and experimental data of the buildings in the US therefore it might not be compatible with the building in Indonesia, especially surveyed buildings in Banjarnegara. The reason is the buildings in the US fulfilled the earthquake-resistant building provision meanwhile the surveyed buildings did not.

A Strain Rate-Dependent Damage Evolution Model for Concrete Based on Experimental Results

There are various definitions of damage variables from the existing damage models. The calculated damage value by the current methods still could not well correspond to the actual damage value. Therefore, it is necessary to establish a damage evolution model corresponding to the actual damage evolution. In this paper, a strain rate-sensitive isotropic damage model for plain concrete is proposed to describe its nonlinear behavior. Cyclic uniaxial compression tests were conducted on concrete samples at three strain rates of 10−3s−1, 10−4s−1, and 10−5s−1, respectively, and ultrasonic wave measurements were made at specified strain values during the loading progress. A damage variable was defined using the secant and initial moduli, and concrete damage evolution was then studied using the experimental results of the cyclic uniaxial compression tests conducted at the different strain rates. A viscoelastic stress-strain relationship, which considered the proposed damage evolution model, was presented according to the principles of irreversible thermodynamics. The model results agreed well with the experiment and indicated that the proposed damage evolution model can accurately characterize the development of macroscopic mechanical weakening of concrete. A damage-coupled viscoelastic constitutive relationship of concrete was recommended. It was concluded that the model could not only characterize the stress-strain response of materials under one-dimensional compressive load but also truly reflect the degradation law of the macromechanical properties of materials. The proposed damage model will advance the understanding of the failure process of concrete materials.