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The purpose of this paper is to investigate the influence of the oxidation on the cracks of DZ125L nickel-based superalloy thin-walled parts in laser metal direct forming (LMDF).

Thin-walled cylinders were fabricated in protective atmosphere with different oxygen contents in order to reveal the influence of oxidation on the morphology of cracks. The influence of oxidation on the cracks was investigated in detail by measuring the wall thicknesses of cylinders, the residual stress in the top surface of the cylinders and the composition of the cracks. Finally, the validity of the results was verified by fabricating a thin-walled turbine blade in protective atmosphere.

The experimental results showed that wall thickness fluctuation of cylinders, unequal residual stress distribution of cylinders and the oxides in the crack were all the critical factors which led to crack of DZ125L thin-walled parts. Thin-walled turbine blades with no cracks can be fabricated when the oxygen content was about less than 150 ppm in protective atmosphere.

The appropriate oxygen content in protective atmosphere is helpful for fabricating thin-walled parts of nickel-based superalloy like DZ125L, and the results can show what will happen at different oxygen levels. Moreover, the results show that the cracks can be eliminated as the oxygen content reduce to less than 150 ppm rather less than 10 ppm or even less, which can reduce the cost of protective gas as forming thin-walled parts of nickel-based superalloy such as DZ125L.

The appropriate oxygen content in protective atmosphere is helpful for fabricating thin-walled parts of nickel-based superalloy like DZ125L. However, when heavy solid parts of some other material other than DZ125L were fabricated, the oxygen content of less than 150 ppm may be not suitable.

The influence of oxidation on the cracks of DZ125L thin-walled parts in LMDF was investigated in detail, and a DZ125L thin-walled turbine blade with no cracks was fabricated by adjusting the oxygen content in protective atmosphere.

As an efficient self-healing intelligent material, the encapsulation-based self-healing resin mineral composite (SHC) has a broad application prospect.

Aiming at the cracking performance of SHC, the dynamic load condition is employed to replace the traditional static load condition, the initial damage of the material is considered and the triggered cracking process and influencing factors of SHC are analyzed based on the extended finite element method (XFEM). In addition, the mechanism of matrix cracking and microcapsule triggered cracking process is explained from the microscopic point of view, and the cracking performance conditions of SHC are studied. On this basis, the response surface regression analysis method is used to obtain a second-order polynomial model of the microcapsule crack initiation stress, the interface bonding strength and the matching relationship between elastic modulus. Therefore, the model could be used to predict the cracking performance parameters of the microcapsule.

The interfacial bonding strength has an essential effect on the triggered cracking of the microcapsule. In order to ensure that the microcapsule can be triggered cracking normally, the design strength should meet the following relationship, that is crack initiation stress of microcapsule wall < crack initiation stress of matrix < interface bonding strength. Moreover, the matching relationship between elastic modulus has a significant influence on the triggered cracking of the microcapsule.

The results provide a theoretical basis for further oriented designing of the cracking performance of microcapsules.

In the purpose of the section, the cracks that are in the construction domain may be common and usually fixed with the human inspection which is at the visible range, but for the cracks which may exist at the distant place for the human eye in the same building but can be captured with the camera. If the crack size is quite big can be visible but few cracks will be present due to the flaws in the construction of walls which needs authentic information and confirmation about it for the successful completion of the wall cracks, as these cracks in the wall will result in the structure collapse.

In the modern era of digital image processing, it has captured the importance in all the domain of engineering and all the fields irrespective of the division of the engineering, hence, in this research study an attempt is made to deal with the wall cracks which are found or searched during the building inspection process, in the present context in association with the unique U-net architecture is used with convolutional neural network method.

In the construction domain, the cracks may be common and usually fixed with the human inspection which is at the visible range, but for the cracks which may exist at the distant place for the human eye in the same building but can be captured with the camera. If the crack size is quite big can be visible but few cracks will be present due to the flaws in the construction of walls which needs authentic information and confirmation about it for the successful completion of the wall cracks, as these cracks in the wall will result in the structure collapse. Hence, for the modeling of the proposed system, it is considered with the image database from the Mendeley portal for the analysis. With the experimental analysis, it is noted and observed that the proposed system was able to detect the wall cracks, search the flat surface by the result of no cracks found and it is successful in dealing with the two phases of operation, namely, classification and segmentation with the deep learning technique. In contrast to other conventional methodologies, the proposed methodology produces excellent performance results.

The originality of the paper is to find the portion of the cracks on the walls using deep learning architecture.

Cracks on surface are often identified as one of the early indications of damage and possible future catastrophic structural failure. Thus, detection of cracks is vital for the timely inspection, health diagnosis and maintenance of infrastructures. However, conventional visual inspection-based methods are criticized for being subjective, greatly affected by inspector's expertise, labor-intensive and time-consuming.

This paper proposes a novel self-adaptive-based method for automated and semantic crack detection and recognition in various infrastructures using computer vision technologies. The developed method is envisioned on three main models that are structured to circumvent the shortcomings of visual inspection in detection of cracks in walls, pavement and deck. The first model deploys modified visual geometry group network (VGG19) for extraction of global contextual and local deep learning features in an attempt to alleviate the drawbacks of hand-crafted features. The second model is conceptualized on the integration of K-nearest neighbors (KNN) and differential evolution (DE) algorithm for the automated optimization of its structure. The third model is designated for validating the developed method through an extensive four layers of performance evaluation and statistical comparisons.

It was observed that the developed method significantly outperformed other crack and detection models. For instance, the developed wall crack detection method accomplished overall accuracy, F-measure, Kappa coefficient, area under the curve, balanced accuracy, Matthew's correlation coefficient and Youden's index of 99.62%, 99.16%, 0.998, 0.998, 99.17%, 0.989 and 0.983, respectively.

Literature review lacks an efficient method which can look at crack detection and recognition of an ensemble of infrastructures. Furthermore, there is absence of systematic and detailed comparisons between crack detection and recognition models.

Large displacement misalignment under the action of active faults can cause complex three-dimensional deformation in subway tunnels, resulting in severe damage, distortion and misalignment. There is no developed system of fortification and related codes to follow. There are scientific problems and technical challenges in this field that have never been encountered in past research and practices.

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation based on the open-cut tunnel project of the Urumqi Rail Transit Line 2, which passes through the Jiujiawan normal fault. The test simulated the subway tunnel passing through the normal fault, which is inclined at 60°. This research compared and analyzed the differences in mechanical behavior between two types of lining section: the open-cut double-line box tunnel and the modified double-line box arch tunnel. The structural response and failure characteristics of the open-cut segmented lining of the tunnel under the stick-slip part of the normal fault were studied.

The results indicated that the double-line box arch tunnel improved the shear and longitudinal bending performance. Longitudinal cracks were mainly distributed in the baseplate, wall foot and arch foot, and the crack position was basically consistent with the longitudinal distribution of surrounding rock pressure. This indicated that the longitudinal cracks were due to the large local load of the cross-section of the structure, leading to an excessive local bending moment of the structure, which resulted in large eccentric failure of the lining and formation of longitudinal cracks. Compared with the ordinary box section tunnel, the improved double-line box arch tunnel significantly reduced the destroyed and damage areas of the hanging wall and footwall. The damage area and crack length were reduced by 39 and 59.3%, respectively. This indicates that the improved double-line box arch tunnel had good anti-sliding performance.

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation. This system increased the similarity ratio of the test model, improved the dislocation loading rate and optimized the simulation scheme of the segmented flexible lining and other key factors affecting the test. It is of great scientific significance and engineering value to investigate the structure of subway tunnels under active fault misalignment, to study its force characteristics and damage modes, and to provide a technical reserve for the design and construction of subway tunnels through active faults.

There have been several recent cases reported in Malaysian newspapers of complaints about the impact of construction works on the physical conditions of the surrounding buildings. The purpose of this paper is to present the findings of a study conducted on a complaint received by the Local Authority in Selangor, Malaysia, about the impact of adjacent new construction works on the conditions of existing buildings in the neighbouring vicinity.

The sample case study consists of 28 units of two‐storey terrace houses, and the instrument used was the inspection form for building inspections. A building survey was carried out for all the buildings in the case study. Two teams conducted the survey. Each team was led by a professional building surveyor and assisted by two assistant building surveyors. Apart from basic surveying tools, a digital calliper was also used to measure cracks. Crack‐width data were collected and analysed using the statistical package for social sciences (SPSS) software.

The findings show that the adjacent new construction works have impacted the existing buildings nearby. A numbers of cracks of various magnitudes were identified in all the existing houses. One significant finding is that there appears to be no significant relationship between the cracks on the interior and the exterior, nor between the original and the renovated parts, of the existing buildings.

The significant number of cracks identified in the existing houses implies that the cracks were associated with the impacts from the new construction works. However, the primary cause of the building cracks was difficult to determine. It is therefore proposed that the Local Authority should establish guidelines at the local level for new construction works to prepare an inspection report on the condition of existing buildings in the surrounding area before the project commences. Building condition reports can then be used for reference in the event of claims received from the surrounding building owners alleging that the new construction works have adversely impacted the existing conditions of nearby buildings.

This paper reviews the most common building defects and techniques for their diagnosis. Problem areas are listed by their location within a structure and the information is presented in tabular form for easy reference. The first paper in this series — ‘Effective diagnosis of material problems and defects in building and construction’ — was published in Structural Survey Volume 4 Number 1. Part 3 will be an appraisal of better known in situ testing and NDT techniques featuring specific items of equipment.

This paper aims to analyze a failure case of a P110 tube in a CO₂ flooding well.

The chemical composition, microstructure and mechanical properties of the failed P110 tubing steel were tested, and met the API Spec 5CT standard. The fractures were investigated by scanning electron microscopy and energy dispersive spectroscopy.

Fracture was induced by stress corrosion cracking (SCC) and that the stress concentration caused by the mechanical damage played an important role in the failure. The failure case is a SCC failure affected by mechanical damage and galvanic corrosion.

The effect of the infiltration of groundwater was studied in the failure case. The stress concentration caused by the mechanical damage played an important role in the failure.

This paper aims to propose a system for defect detection in constructed elements that is able to indicate deformity positions. It also evaluates the defects in finishing materials of constructed building elements to support the subjective visual quality investigation of the aesthetics of an architectural work.

This strategy depends on defect features analysis that evaluates the defect value in digital images using digital image processing methods. The research uses the three-dimensional (3D) modeling techniques and image processing algorithms to generate a system that is able to perform some of the monitoring activities by computers. Based on the collected site scans, a 3D model is created for the building. Then, several images can be exported from the 3D model to investigate a specific element. Different image denoizing techniques are compared such as mean filter, median filter, Wiener filter and Split–Bregman iterations. The most efficient technique is implemented in the system. Then, the following six different methods are used for image segmentation to separate the concerned object from the background; color segmentation, region growing segmentation, histogram segmentation, local standard deviation segmentation, adaptive threshold segmentation and mean-shift cluster segmentation.

The proposed system is able to detect the cracks and defected areas in finishing works and calculate the percentage of the defected area compared to the total captured area in the photo with high accuracy.

The proposed system increases the precision of decision-making by decreasing the contribution of human subjective judgment. Investigation of different finishing surfaces is applied to validate the proposed system.

Places of worship have historically been maintained using traditional building management techniques, including regular monitoring, upkeep and maintenance provided by their religious communities. This paper examines the conservation issues arising after the forced displacement of the traditional custodians, which is a significant concern in conflict-ridden environments.

As a unique example of a long-term conflict, the divided Cyprus provides this research with illustrative cases to derive the data. The research employs content analysis of official documents, physical observations and interviews with conservation professionals.

This research demonstrates the human and environmental factors impacting the conservation of the material fabric and the use-related challenges stemming from the intangible significance of the religious legacy belonging to displaced communities. It highlights the urgency to formulate more effective mechanisms and regulatory frameworks to address vulnerability issues promptly.

Preservation problems on religious heritage buildings arising from the loss of traditional custodians after conflicts are an under-researched area in conservation literature. Drawing on research that was conducted several decades after the displacement of Cypriot communities, this paper reveals new insights into the magnitude of the conservation problems and the use-related complexities that need to be addressed to formulate mutually acceptable solutions for a sustainable future.