An end-to-end bidirectional authentication system for pallet pooling management through blockchain internet of things (BIoT)

Pallet pooling is regarded as a sustainable and cost-effective measure for the industry, but it is challenging to advocate due to weak data and pallet authentication. In order to establish trust between end-users and pallet pooling services, the authors propose an end-to-end, bidirectional authentication system for transmitted data and pallets based on blockchain and internet-of-things (IoT) technologies. In addition, secure data authentication fosters the pallet authenticity in the whole supply chain network, which is achieved by considering the tag, location, and object-specific features. To evaluate the object-specific features, the scale invariant feature transform (SIFT) approach is adopted to match key-points and descriptors between two pallet images. According to the case study, it is found that the proposed system provides a low bandwidth blocking rate and a high probability of restoring complete data payloads. Consequently, positive influences on end-user satisfaction, quality of service, operational errors, and pallet traceability are achieved through the deployment of the proposed system

Damage detection of structures subject to nonlinear effects of changing environmental conditions

Damage detection of civil structures has been carried out by mainly analysing the vibration properties of the structures which change when damages occur. However, these properties are also affected by the changing environmental conditions the structures are face with, and these conditions usually produce nonlinear effects on the vibration properties. Hence, a method is proposed in this paper to analyse structures subjected to nonlinear effects of environmental conditions. The method first applies Principal Component Analysis (PCA) on a bank of damage sensitivity features, followed by applying Gaussian Mixture Model on the obtained first principal component scores to cluster the data into several linear regions. By creating a baseline for each linear region using two extreme and opposite environmental conditions, and adding new measurements to the baseline one at a time followed by applying PCA, damage detection can be achieved. The method is validated on a numerical truss structure model and on the Z24 Bridge. The results demonstrate the ability of the method to analyse structures under nonlinear environmental effects

The Behavior of Retaining Walls Under 1999 Chi-Chi Earthquake

This paper reports failure of retaining structures related to the 1999 Chi-Chi earthquake. On September 21 of 1999, an earthquake with a magnitude of 7.3 on the Richter scale struck Taiwan. At the site near Tou-Sheh, overturning failure was observed on a 2.5 m-high gravity wall located near the epicenter. At the site near the Temple of Ten-thousand Buddha, a masonry wall constructed with cobble was damaged. Upper part of wall shifted outward about 0.2 m with respect to its lower part. At the site of Cinema-Culture Town, a gravity wall built on top of the Che-Lung-Pu fault was severely damaged. The heel of the wall was uplifted by the fault rupture. At the parking lot of the Lalu Resort, the retaining wall constructed on a slope moved down the slope during the earthquake. A circular sliding surface can be observed in the collapsed backfill. At the entrance of National Chi-Nan University, a geogrid-reinforced wall was severely damaged during the earthquake. Reinforcing strips were pulled out under the seismic load and fill materials fell out

Separating damage from environmental effects affecting civil structures for near real-time damage detection

Analyzing changes in vibration properties (e.g. natural frequencies) of structures as a result of damage has been heavily used by researchers for damage detection of civil structures. These changes, however, are not only caused by damage of the structural components, but they are also affected by the varying environmental conditions the structures are faced with, such as the temperature change, which limits the use of most damage detection methods presented in the literature that did not account for these effects. In this article, a damage detection method capable of distinguishing between the effects of damage and of the changing environmental conditions affecting damage sensitivity features is proposed. This method eliminates the need to form the baseline of the undamaged structure using damage sensitivity features obtained from a wide range of environmental conditions, as conventionally has been done, and utilizes features from two extreme and opposite environmental conditions as baselines. To allow near real-time monitoring, subsequent measurements are added one at a time to the baseline to create new data sets. Principal component analysis is then introduced for processing each data set so that patterns can be extracted and damage can be distinguished from environmental effects. The proposed method is tested using a two-dimensional truss structure and validated using measurements from the Z24 Bridge which was monitored for nearly a year, with damage scenarios applied to it near the end of the monitoring period. The results demonstrate the robustness of the proposed method for damage detection under changing environmental conditions. The method also works despite the nonlinear effects produced by environmental conditions on damage sensitivity features. Moreover, since each measurement is allowed to be analyzed one at a time, near real-time monitoring is possible. Damage progression can also be given from the method which makes it advantageous for damage evolution monitoring

Seismic performance of reinforced concrete interior beam-column joints with novel reinforcement detail

Horizontal stirrups are normally required in reinforced concrete (RC) beam-column joints (BCJs) for resisting shear forces in seismic design. For RC moment-resisting frames subjected to a high lateral load, a large number of stirrups are needed in joint cores. This may cause reinforcement congestion, leading to construction difficulty and insufficient concrete compaction, which can result in poor seismic performance. In this study, a novel reinforcement detail in the form of unbonded diagonal bars mechanically anchored at beam ends is proposed for RC interior BCJs. The detail alleviates the reinforcement congestion through partially replacing horizontal stirrups, and improves the seismic performance of BCJs by plastic hinge relocation and input shear force reduction mechanisms. Four 2/3-scale RC interior BCJ specimens were prepared and tested under quasi-static cyclic load, including one specimen designed with the current code and three specimens adopting the proposed reinforcement detail. Test results show that the proposed reinforcement detail is able to relocate the plastic hinges away from beam-joint interfaces as well as improve the loading capacity, energy dissipation capacity, stiffness, and bonding condition of beam reinforcements within the cores of BCJs. The combined use of stirrups and the proposed reinforcement detail significantly enhances the cracking resistance and reduces joint distortion, while additional amount of stirrups results in a marginal improvement. Moreover, an analytical model considering plastic hinge relocation and input joint shear force reduction is proposed for BCJs with the novel reinforcement detail. The model can adequately predict the failure mode and loading capacity of BCJ specimens

A regression-based damage detection method for structures subjected to changing environmental and operational conditions

© 2020 Elsevier Ltd Damage detection of civil engineering structures during the past decade has focused on eliminating the effects of the changing environmental and operational conditions, from the effects of damage. In the literature, a regression analysis has been adopted to construct a model between the vibration properties of structures, and the environmental and operational parameters to represent the undamaged state of the structures, for damage detection. However, using the environmental and operational parameters in the analysis has several limitations. For example, these parameters are not always available which may affect the performances of the damage detection methods. Regression between the vibration properties only has also been proposed in the literature where multivariate statistical tools have been adopted to extract the relationships among the properties. However, these methods have the problem that it is more difficult to detect damage in the multivariate situations and a regression target is usually needed, which is difficult to determine. Therefore, a damage detection method which uses the simple regression analysis, is developed in this paper. The vibration properties of structures are used as both the independent and dependent variables in the developed method. This has the advantages that the environmental and operational conditions are not needed and the multivariate statistical tools are not required for data processing. The developed method is applied to a beam structure model and the Z24 Bridge, in Switzerland, and the results obtained demonstrate that the method can successfully classify between undamaged and damaged states. The traditional regression analysis method is also applied to the two structures and it was found that better results are obtained using the method developed in this paper

Experimental study on seismic vibration control of stockers in wafer and LCD panel fabs

Automated stocker system is widely used in semiconductor and liquid crystal display (LCD) industries for handling and storage of valuable wafers or glass panels. Massive front opening unified pods (foups) containing wafers, or cassettes storing glass panels, are placed in shelf stockers during manufacturing. Although several preventative measures have been taken, during the past earthquakes, substantial financial loss from the industries were reported, and one of the main causes was attributed to collision of the foups or cassettes and shake off from the shelfs. This paper proposes a methodology of incorporating viscous fluid dampers into the stokers to mitigate their seismic response. Unlike conventionally been done in buildings where dampers are placed between adjacent stories, it is proposed to install dampers in between the ceiling and top of the stocker. Such configuration utilizes the large velocity at the stocker top under vibration, resulting in smaller damper size, and enables a leverage mechanism that requires smaller damper force to resist the stocker’s vibration. Both shake table tests and simulation of a full-scale stocker under realistic earthquakes have been conducted. Results indicate that both displacement and acceleration responses of the stocker can be significantly reduced, and dynamic response of the stocker under seismic excitations can be well predicted

Damage detection under temperature conditions using PCA – an application to the Z24 Bridge

Vibration properties of civil structures, which are commonly analysed for damage detection, are affected by changing environmental and operational conditions, and most notably are subjected to bilinear effects from changing ambient temperature conditions. Therefore, damage detection in structures during the past decade has focused on eliminating the effects of these changing environments that affect the vibration properties of the structures. Several methods have been proposed in the literature to tackle the non-linear effects from changing environments. However, these methods can only analyse systems (e.g. natural frequency–environmental and operational system) that have an incremental change in relationship; they cannot model the bilinear effects from the changing temperature conditions, which may lead to false alerts. Hence, a damage detection method is proposed in this paper to tackle the piecewise effects from changing temperature conditions. The method makes use of a Gaussian mixture model to separate the different effects acting on the structures and uses principal component analysis for data processing. The method is applied to the Z24 Bridge, in Switzerland, which was subjected to bilinear effects from changing temperature conditions. The results obtained demonstrate that the proposed method successfully takes into account the piecewise effects to indicate the presence of damage

Effects of polyethylene fibre dosage and length on the properties of high-tensile-strength engineered geopolymer composite

Engineered Geopolymer Composites (EGCs) have attracted increasing attention as an alternative to Engineered Cementitious Composites (ECCs) by using geopolymer to replace cementitious matrix in ECC, which improves the environmental sustainability by reducing the high cement and superplasticizer proportions. However, EGC generally needs a high temperature curing to enhance its early strength, and current EGCs with PVA fibre presents limited tensile performance. This paper aims to develop a high-tensile-strength EGCs reinforced by polyethylene (PE) fibre. The influence of fibre dosage (1.5%, 1.75% and 2.0%) and length (6 mm, 12 mm and 18 mm) on the engineering properties of EGC were examined. The results indicate that increasing either fibre dosage or length obviously decreases the flowability of EGC due to the skeleton formed by fibre. With the increase of fibre dosage, the compressive strength of the EGC with 12 mm fibre increases due to the enhanced fibre bridging effect, while that of the EGC with 18 mm fibre decreases due to the air entrapping effect. Consequently, the EGC with 2% of 6 mm or 12 mm fibre exhibit higher compressive strength than that with 18 mm fibre. The use of fibre at a high dosage (e.g., 2%) tends to cause the fibre cluster, which reduces the tensile strength of EGC, especially for the EGC with 18 mm fibre. A longer fibre length increases the tensile strength of EGC by enhancing the fibre-bridging effect. Increasing either fibre dosage or length is beneficial in improving the tensile strain capacity and crack control capacity of EGC. Besides, the fibre inclusion reduces the drying shrinkage of EGC through the restricting effect, although excessive fibre tends to introduce more voids and slightly increases their drying shrinkage. Furthermore, the environmental assessment indicates that PE fibre reinforced EGCs exhibit dramatically lower environmental impacts than the conventional M45 and high-tensile-strength ECCs

Environmental adaptability and stress tolerance of Laribacter hongkongensis: a genome-wide analysis

<p>Abstract</p> <p>Background</p> <p><it>Laribacter hongkongensis </it>is associated with community-acquired gastroenteritis and traveler's diarrhea and it can reside in human, fish, frogs and water. In this study, we performed an in-depth annotation of the genes in its genome related to adaptation to the various environmental niches.</p> <p>Results</p> <p><it>L. hongkongensis </it>possessed genes for DNA repair and recombination, basal transcription, alternative σ-factors and 109 putative transcription factors, allowing DNA repair and global changes in gene expression in response to different environmental stresses. For acid stress, it possessed a urease gene cassette and two <it>arc </it>gene clusters. For alkaline stress, it possessed six CDSs for transporters of the monovalent cation/proton antiporter-2 and NhaC Na⁺:H⁺antiporter families. For heavy metals acquisition and tolerance, it possessed CDSs for iron and nickel transport and efflux pumps for other metals. For temperature stress, it possessed genes related to chaperones and chaperonins, heat shock proteins and cold shock proteins. For osmotic stress, 25 CDSs were observed, mostly related to regulators for potassium ion, proline and glutamate transport. For oxidative and UV light stress, genes for oxidant-resistant dehydratase, superoxide scavenging, hydrogen peroxide scavenging, exclusion and export of redox-cycling antibiotics, redox balancing, DNA repair, reduction of disulfide bonds, limitation of iron availability and reduction of iron-sulfur clusters are present. For starvation, it possessed phosphorus and, despite being asaccharolytic, carbon starvation-related CDSs.</p> <p>Conclusions</p> <p>The <it>L. hongkongensis </it>genome possessed a high variety of genes for adaptation to acid, alkaline, temperature, osmotic, oxidative, UV light and starvation stresses and acquisition of and tolerance to heavy metals.</p