Damage Ratio Research Articles

Automated macular segmentation can distinguish glaucomatous from compressive optic neuropathy

PurposeTo compare macular damage in glaucomatous optic neuropathy (GON) and compressive optic neuropathy (CON) and assess its diagnostic accuracy in distinguishing between diseases.MethodsObservational, cross-sectional, single-center study. Patients with GON, CON, and healthy controls were included according to the eligibility criteria. An automated spectral-domain optical coherence tomography (SD-OCT) algorithm was used to segment the circumpapilary retinal nerve fiber layer (cpRNFL) and macula. The layer thickness was measured in each sector according to the Early Treatment Diabetic Retinopathy Study and the 6-sector Garway-Heath-based grids. Data was compared across all study groups, and the significance level was set at 0.05.ResultsSeventy-five eyes of 75 participants, 25 with GON, 25 with CON, and 25 healthy controls (CG), were included. Macular thickness was diminished in the ganglion cell complex of GON and CON patients compared to CG (p<0.05). The best Garway-Heath-based grid parameters for distinguishing GON and CON were the nasal-inferior (NI) and nasal-superior sectors and the NI/temporal inferior (TI) damage ratios in the macular ganglion cell (mGCL) and inner plexiform (IPL) layers. Moreover, the combination of the NI sector and NI/TI damage ratios in both layers had higher discriminative power (AUC 0.909; 95% CI 0.830–0.988; p<0.001) than combining parameters in each layer separately.ConclusionOur findings suggest that the evaluation of macular segmented layers damage by SD-OCT may be a helpful add-on tool in the differential diagnosis between GON and CON.

Experimental Analysis of Channel Steel Member under Tension Load with Damage in the Unconnected Legs.

Damage occurring to steel element structures is highly possible due to tearing ruptures, corrosion, or the adoption of sudden loads. The damage has a great effect on their capacity to bear load and the corresponding elongation, as well as the distribution of the stresses in the cross-section of the element. Therefore, in the present research, experimental tests were carried out on 15 specimens of channel steel elements with different damage ratios in the unconnected legs and at different locations along the element's length. Through the test, the load and the corresponding elongation values were obtained for the control and damaged specimens. From the study of the different variables, it was demonstrated that the damage location does not significantly affect the load capacity, with a maximum difference of 1.9%. With the presence of the damage in only one leg at a ratio of less than or equal to 40%, the prediction of the value of the loss in the load is within the safe limit. However, if this ratio increases, there is a defect in calculating the loss in the load as it is greater than the effect of the damage. If there is any damage in the two legs of the channel together, the prediction of the loss of load is within the safe limit, where the loss is less than the effect of the damage ratio. We propose a model that can predict the capacitance of the axial load of steel channel elements through identifying the ratio of damage in the unconnected leg.

Behavior of Damaged Continuous Reinforced Concrete Beams Repaired by CFRP Sheets

Despite the widespread use of RC continuous beams, the performance of these beams, when repaired via Fiber Reinforced Polymer (FRP) composite material, has received less attention. Furthermore, several features of the flexural aspect of repaired RC continuous beams still demand experimental and analytical evaluation. However, many anchoring methods have been developed to delay premature failure in the RC beams, which are strengthened with FRP composite materials. The plan of this experimental study consists of eight continuous beams cast with dimensions (150*250*2800) mm considering the length of the clear span is 1300mm. Except for one, all specimens were attached via Carbon FRP sheets about 70% of the span length in negative and positive moment zones beyond a predetermined damage level. Moreover, this study suggested modifying the end-anchor technique and adding CFRP layers with (45, 65, and 95) % as damage ratios. According to the results, the optimal percentage of restored ultimate capacity was 108.8% with peeling-off concrete cover failure mode, which was obtained from using an end-anchor and two layers of the sheet. Also, increasing the damage ratio leads to a decline in toughness and ductility values. In addition, it is possible to repair the structure with a 95% damage ratio rather than remove it.

SIMPLIFIED ASSESSMENT OF EARTHQUAKE DAMAGE RATIO FOR LOW- AND MID-RISE BUILDINGS BASED ON ENERGY BALANCE CONSIDERING SOIL-STRUCTURE INTERACTION

In order to easily assess the damage caused by earthquakes in low- and mid-rise building complexes, this paper proposes a simplified method for assessing the damage ratio in real building complexes by combining a seismic evaluation method based on the energy balance and reliability theory. This method enables the effect of dissipation damping to be taken into account, and is effective for the evaluation of the largest foreshocks and aftershocks in addition to the main shock. A comparison of the damage ratio calculated using this method with the actual damage ratio from the 1995 Hyogo-ken Nanbu Earthquake showed that the two ratios generally matched with each other. In terms of applications, this method provides a standard for calculating the base shear coefficient of low-rise reinforced concrete buildings for continued use after an earthquake from the viewpoint of performance design.

2018 Kerala Flood Damage: Survey, Identification, and Damage Prediction Models Using Machine Learning

The 2018 flood experienced by Kerala, the southernmost state of India, has affected thousands of lives, resulting in heavy financial loss (248,930 million INR) and structural damage (129,420 residential buildings have been reported to be damaged). Depth versus damage relationships have been used conventionally for flood emergency decision-making; however, these are approximate and do not account for all the significant factors involved in the flood damage assessment. An extensive questionnaire survey was conducted in this study to collect data comprising significant parameters of flood-damaged residential buildings due to the 2018 Kerala flood event. The damage to the buildings was expressed in terms of damage ratios, and the buildings were classified into various damage states according to their damage ratios. Machine learning (ML) techniques, such as random forest, naïve Bayes, decision tree, K-nearest neighbors, AdaBoost, XGBoost, support vector machine, LightGBM, and CatBoost, were used in this study to develop models to predict and classify the buildings into various flood damage states. Results indicated that almost all the tree-based ML techniques performed well, and the random forest model was obtained as the best-performing classification model for flood damage prediction with 84% accuracy. Further SHAP (SHapely Additive exPlanations) analysis was conducted to explore the relative importance of the different parameters involved in damage prediction.

Методические основы синтеза моделей развития горных работ для управления процессом воспроизводства очистного фронта угольных шахт

This article presents the results of optimizing the reliability and reliability of the time forecast’s development reserves of the coal mine long wall areas and the preparation time of the face longwall line. A scheme of the reproduction the long wall front process in the form of a decision tree model has been developed. The dependences of the optimal probability of the absence of coal mining losses and the optimal dynamic time reserve on the reliability of longwall and preparatory work and on the ratio of damage in case of shortage, as well as the costs of maintaining the cleaning front, are established. It is shown that when forming a mining development plan, the value of the optimal dynamic time reserve should be determined for each treatment face. It is determined that when providing dynamic redundancy of the process of reproduction of the longwall front, the possibilities of performing degassing and drainage of mineral reserves being prepared for extraction are more fully realized which positively affects the level of reliability and safety of longwall operations.

Development and implementation of a metaphase DNA model for ionizing radiation induced DNA damage calculation

Objective. To develop a metaphase chromosome model representing the complete genome of a human lymphocyte cell to support microscopic Monte Carlo (MMC) simulation-based radiation-induced DNA damage studies. Approach. We first employed coarse-grained polymer physics simulation to obtain a rod-shaped chromatid segment of 730 nm in diameter and 460 nm in height to match Hi–C data. We then voxelized the segment with a voxel size of 11 nm per side and connected the chromatid with 30 types of pre-constructed nucleosomes and 6 types of linker DNAs in base pair (bp) resolutions. Afterward, we piled different numbers of voxelized chromatid segments to create 23 pairs of chromosomes of 1–5 μm long. Finally, we arranged the chromosomes at the cell metaphase plate of 5.5 μm in radius to create the complete set of metaphase chromosomes. We implemented the model in gMicroMC simulation by denoting the DNA structure in a four-level hierarchical tree: nucleotide pairs, nucleosomes and linker DNAs, chromatid segments, and chromosomes. We applied the model to compute DNA damage under different radiation conditions and compared the results to those obtained with G0/G1 model and experimental measurements. We also performed uncertainty analysis for relevant simulation parameters. Main results. The chromatid segment was successfully voxelized and connected in bps resolution, containing 26.8 mega bps (Mbps) of DNA. With 466 segments, we obtained the metaphase chromosome containing 12.5 Gbps of DNA. Applying it to compute the radiation-induced DNA damage, the obtained results were self-consistent and agreed with experimental measurements. Through the parameter uncertainty study, we found that the DNA damage ratio between metaphase and G0/G1 phase models was not sensitive to the chemical simulation time. The damage was also not sensitive to the specific parameter settings in the polymer physics simulation, as long as the produced metaphase model followed a similar contact map distribution. Significance. Experimental data reveal that ionizing radiation induced DNA damage is cell cycle dependent. Yet, DNA chromosome models, except for the G0/G1 phase, are not available in the state-of-the-art MMC simulation. For the first time, we successfully built a metaphase chromosome model and implemented it into MMC simulation for radiation-induced DNA damage computation.

Prediction and detection of potholes in urban roads: Machine learning and deep learning based image segmentation approaches

The number of potholes in the world has rapidly increased due to the growth of vehicles, temperature changes, and the concentration of the population. Potholes cause danger in driving and reduce passengers' comfort. Therefore, an accurate prediction of number of potholes provides timely maintenance and rehabilitation, and also it enhances safety for drivers. This study aims to improve the accuracy of number of potholes prediction model by considering independent variables such as minimum temperature, relative humidity, precipitation, and traffic volume. The model was established by conducting variable analysis. Various machine learning methods were then employed to develop an optimal model that provides the highest accuracy in predicting pothole occurrence. The study also suggests a computer vision-based system for spotting potholes based on the image segmentation method, followed by calculating the damage ratio. The results confirm that the proposed models have the potential in predicting and detecting pothole occurrence.

Full-Scale Experiments of Water-Mist Systems for Control and Suppression of Sauna Fires

Sauna is a common fixture in many facilities; a specific fire-protection system is typically designed and installed for this application, as short circuits or direct contact with incandescent materials may result in a fire. Water mist has been recently considered as a promising option for this purpose; so, assessing its control and suppression capability in a sauna configuration has become of paramount importance for designers and engineers. To this end, an unprecedented real-scale test rig was built and instrumented with thermocouples and a hot-plate thermometer towards the evaluation of water-mist performance against various fire scenarios and, ultimately, to provide guidelines to designers. Timber benches were employed as target materials, while the fire was initiated in a wood crib. Design parameters, such as initial room temperature, location of the ignition source, nozzle-to-wall distance, and air gap between benches and wall, were varied, also including natural ventilation in a dedicated experiment. The system proved successful in controlling and containing the fire: bench damage ratio—selected as a quantitative parameter to assess water-mist performance—was consistently lower than 5%. However, extinction was not always achieved, especially under the most challenging configuration in terms of ventilation, initial room temperature, and nozzle-to-wall distance.

Real-time drive-by bridge damage detection using deep auto-encoder

Structural health condition monitoring of bridge structures has been a concern in the last decades due to their aging and deterioration, in which the core task is damage detection. Recently, the drive-by method has gained much attention as it only needs several sensors installed on the passing vehicle. In this paper, we proposed an automatic damage detection method, which can be exploited in real time when the vehicle is passing the bridge. There are three steps in the proposed method: (1) The vehicle’s framed short-time vibrations instead of full-length data are utilized for training a deep auto-encoder model; at this stage, not commonly used time-domain accelerations of the passing vehicle, but its selected frequency-domain responses are employed to circumvent the influence of noises, (2) For the bridge with unknown health conditions, damage indicators can be extracted from its passing vehicle’s short-time vibration data using the trained model, and (3) The bridge’s health states are determined by real-time extracted damage indicators. To verify the proposed idea, a U-shaped continuous beam and a model truck are used to simulate the vehicle bridge interaction system in engineering. Results showed that the proposed method could identify the bridge’s damage with an accuracy of 86.2% when different severity was considered. In addition, it was observed that higher damage severity could not be revealed by greater values of damage indicators in the laboratory test. Instead, a novel index called identified damage ratios was employed as a reference for assessing the severity of the bridge’s damage. It was shown that with the increase in damage severity, the index would increase and gradually approach 100%.

Analysis of LVE behaviour and fatigue damage evolution of asphalt pavements with different interface conditions in an accelerated full-scale experiment

ABSTRACT For better optimization of pavement design and management, accelerated full-scale pavement tests (APT) represent very efficient tools to study pavement behaviour from initial to damaged condition. This paper presents an experimental study where three asphalt pavements with different interface conditions between the asphalt layers were tested in an APT experiment. Asphalt layer strains, FWD deflections, and surface cracking were monitored during the experiment. First, strain signals and pavement surface deflections measured at the beginning of the experiment, were used to characterize the viscoelastic properties of the asphalt layers. Then the measurements were used to analyze the fatigue behaviour of the experimental pavements, and the evolution of their level of damage to traffic. The analysis showed that in such asphalt pavements, asphalt strains, which varied significantly with the increase of load cycles, were not suitable for estimating an ‘average’ asphalt layer damage. In order to monitor the general pavement behaviour, a new damage ratio was introduced, based on FWD back-calculated moduli of the asphalt layers, that allowed to observe a stiffness increase of the asphalt layers at the beginning of the loading due to aging and post-compaction, and then fatigue damage evolution which had a very good correspondence with surface cracking.

The influence of ASCE 7–16 wind load provisions on a vulnerability model of Florida residential construction

The Florida Public Hurricane Loss Model is a probabilistic risk model designed to estimate wind induced insurance losses to residential infrastructure in Florida. In the physical damage estimation module, Monte Carlo simulation is employed to generate damage matrices as a function of wind speed by comparing probabilistic building component capacities to wind loads. These damage matrices are input to a repair cost algorithm, ultimately producing damage ratios as a function of wind speed for different building classes. It is required that the inventory of residential building models reflect the history of construction practice within Florida. Differing eras of construction are represented by developing component-wise options for probabilistic capacities and load paths, resulting in a suite of hundreds of model variants. Regarding loads, the probabilistic wind load model is based on a directionalized adaptation of ASCE 7, and its representation in the model is kept current with the version adopted by the Florida Building Code (FBC). In 2020 the Florida Building Code adopted by reference ASCE 7–16, which contains important changes to the wind-load provisions. These changes have implications for both the loading and resistance aspects of the physical damage model, thus influencing insured loss projections. This study discusses the development and implementation of these changes within the model and investigates the impacts on the modeled vulnerability of residential structures in Florida. Comparing vulnerability estimates of structures designed before and after the FBC adoption of ASCE 7–16 provide insight into the potential effectiveness of such changes to improve community resilience.

Radiation effects on He+- and H+-implantation for ion slicing of rutile titanium dioxide thin film

The thin film exfoliation mechanisms of He+- and H+- implanted rutile-phase titanium dioxide (r-TiO2), as well as the surface morphology and lattice damage in the implanted r-TiO2 samples, are investigated and compared. Layer splitting in the He+-implanted r-TiO2 samples after annealing at 350 °C was observed. Due to the formation of He bubbles accumulated by nano-defects during annealing, the peak damage ratio in the damage layer is enhanced. The microcracks induced by He+-implantation found in the damage layer correspond two types of defects, which were analyzed. In contrast, H+-implantation in the r-TiO2 samples induced only little lattice damage, and with low annealing temperature the damage is almost fully removed, suggesting thermal activity of the implanted H+-ions in the r-TiO2.

Fragmentation analyses of rocks under high-velocity impacts using the combined finite-discrete element simulation

The impact-induced fragmentation of rock blocks is frequently encountered when the natural hazards (e.g., rockfalls, rockslides, and rock avalanches) occur in mountainous areas. To address the progressive damage and cracking characteristics of rock upon impacting, this paper presents a three-dimensional finite-discrete method (3D-FDEM) study on the complex impact-induced fragmentation process of rock. The influences of the impact velocity on the dynamic fragmentation process, damage evolution, fragment characteristics, fragment flying velocity, and angle were systematically investigated. The parameters as input for simulation were first calibrated by the 3D uniaxial compression tests and rock-impact tests. Then, the complex fragmentation process of rock samples subjected to different impact velocities (i.e., 20–80 m/s) was simulated. The numerical results show that the number of cohesive elements following shear-dominated failures gradually increases with increasing the impact velocity. The fractal method can well describe the distribution of the equivalent fragment length, and the variations of the fractal dimension are consistent with that of the damage ratio, increasing with impact velocity. Both the average and maximum flying velocities of the fragments increase linearly with increasing impact velocity. However, the average flying angle of the fragments shows a sharp increase and then slight increase with increasing the impact velocity.

Empirical estimation based on remote sensing images of insured typhoon-induced economic losses from building damage

Rapid and cost-effective economic loss estimation for buildings in non-life insurance is an important issue for insurance industries in order to provide immediate financial supports to residents affected by natural disasters. This study introduces an empirical approach for economic loss estimation of typhoon-induced building damage from post-disaster remote sensing (RS) images based on insurance records obtained in Osaka and Chiba, Japan affected by the 2018 Typhoon Jebi and the 2019 Typhoon Faxai, respectively. From the insurance records and the analysis of the RS images, we found that area-based loss rates (ALRs) defined as ratio of amount of loss to amount of insured values within a mesh were proportional to building damage ratios (BDRs) identified from number of damaged buildings in the RS images and existing building inventory data, whereas it was still challenging to accurately estimate loss rate for building-by-building even from very high-resolution images. A linear regression function was developed from the relationship between the ALRs and BDRs obtained in this study. We confirmed that the regression function provided a good approximation of the insured losses from the typhoon disasters. The result indicates that typhoon-induced insured losses can be rapidly estimated from the insurance inventory and the analysis of post-disaster RS images without field investigations.

Beam-like damage detection methodology using wavelet damage ratio and additional roving mass

Early damage detection plays an essential role in the safe and satisfactory maintenance of structures. This work investigates techniques use only damaged structure responses. A Timoshenko beam was modeled in finite element method, and an additional mass was applied along their length. Thus, a frequency-shift curve is observed, and different damage identification techniques were used, such as the discrete wavelet transform and the derivatives of the frequency-shift curve. A new index called wavelet damage ratio(WDR) is defined as a metric to measure the damage levels. Damages were simulated like a mass discontinuity and a rotational spring (stiffness damage). Both models were compared to experimental tests since the mass added to the structure is a non-destructive tool. It was evaluated different damage levels and positions. Numerical results showed that all proposed techniques are efficient techniques for damage identification in Timoshenko's beams concerning low computational cost and practical application.

Experimental and numerical study on the influence of shaped charge liner cavity filing on jet penetration characteristics in steel targets

Penetration characteristic (size and shape of penetration craters made in high hardness ARMSTAL 30PM steel) of shaped charge jets formed after detonations of modified PG-7VM warheads was analyzed in the article. Modifications consisted in removing the frontal part of the grenade (fuse, ballistic cap and conductive cone) and introducing of the liner cavity filling made of polyacetal copolymer POM-C. The filings in the form of solid cones with three different heights (33%, 66% and 100% of H - the height of original PG-7VM liner) were placed inside of the hollow cone shaped charge liner. As opposed to the vast majority of previously published works (in which warhead optimization studies were focused on increasing of the depth of penetration in rolled homogeneous armor steel) the main aim of the presented modifications was to maximize the damage ratio (diameters of craters, inlet and outlet holes) of target perforated by shaped charge jet at the cost of the loss of part of the jet penetration capability. According to the best knowledge of the authors such approach to the use of the old PG-7VM warheads has not been analyzed so far. Taking into consideration high stock levels of PG-7VM warheads, and the fact that they are continuously being replaced by more efficient and more sophisticated high-explosive anti-tank warheads, it seems reasonable to look for alternate applications of the warheads withdrawn from the service. Thanks to the introduction of proposed modifications the warheads could be used by special forces or other assault units as directional mines or statically detonated cutting shaped charges as well as by combat engineers as universal charges used in various types of engineering or sapper works. The research included experimental penetration tests and their numerical reproduction in the LS-Dyna software with the simulation methodology defined and validated in previous works of the authors. Small differences (average error = 10–20%) were identified between the experimental and numerical results (dimensions of craters made in steel targets were compared) what confirmed the reliability of the modelling methodology and enabled its use for further optimization of the shapes of fillings. Within the analyzed variants of warheads modifications maximum diameters of penetration craters were obtained for the filling of the height of h = 2/3H. The diameters of holes in individual steel plates were increased by 164%, 70%, 65% (for the first, second and third plate, respectively) in relation to the variant without filling. The results of the study indicated that with the use of different materials of fillings and their various heights it is possible to control the shape of penetration craters pierced in the steel targets.

Strength Deterioration Model of Soft Rock Considering Mesoscopic Bonding–Expansion Coupling Mechanism under Freeze–Thaw Cycles

The mechanical deterioration of soft rocks under freeze–thaw cycles is caused by the accumulation of mesoscopic damage. However, the current freeze–thaw deterioration model for soft rocks does not adequately consider the multiscale correlations, which makes the strength calculation results differ greatly from the test results and cannot fully reveal the damage mechanism of soft rocks under freeze–thaw cycling conditions. In this paper, the bond damage and pore ice expansion laws are considered from the soft-rock mesoscopic bond unit and a multiscale strength deterioration model is proposed. The freeze–thaw deterioration model is extended to intact and cracked soft rocks by the Discrete Element Method (DEM). The results are validated by laboratory tests. The peak strengths of intact soft rocks are calculated within 10% error for different numbers of freeze–thaw cycles, and the macroscopic crack development simulation results are consistent with the laboratory tests. The joints have a significant effect on the damage evolution: the freeze–thaw-induced mesoscopic damage in cracked rocks accumulates at a uniform rate, while the damage in intact soft rocks grows exponentially; the freeze–thaw cracks in cracked soft rocks are distributed between 60 and 90°, with a tensile–shear damage ratio of 1:2; the freeze–thaw cracks in intact soft rocks are distributed around 90°, with a tensile–shear damage ratio of 1:3. The deterioration model proposed in this paper can fully consider the multiscale damage correlations, which renders it easy to promote the application in the freeze–thaw hazard problem of soft rock engineering.

Creep behavior of orthogonal rib box floor of poplar laminated veneer lumber

Poplar laminated veneer lumber (LVL) orthogonal rib box floor is a new type of floor composed of orthogonal LVL rib beams and oriented strand board (OSB). To study the creep performance of the box floor, four 3600 mm × 4800 mm floor specimens were designed and manufactured. The creep tests of the box floor with local damage, repeated load, and different stress ratio loads were conducted. The creep of the floor increased with ambient temperature and humidity. Because of the local damage of the box floor, the creep increased. Repeated loading increased the creep deformation of the floor, and increasing the load accelerated the creep of the floor. Combined with the creep mechanism of wood materials, a creep theoretical calculation formula of the box floor with LVL orthogonal ribs was established. Comparing the creep model analysis with the test data, it was found that the modified Burger mode can well simulate the creep performance of LVL box floor. Therefore, the modified Burger model can be used to calculate the creep deformation of the box floor.

A Method for Assessing Flood Vulnerability Based on Vulnerability Curves and Online Data of Residential Buildings—A Case Study of Shanghai

Flood vulnerability is the key to understanding and assessing flood risk. However, analyzing flood vulnerability requires sophisticated data, which is usually not available in reality. With the widespread use of big data in cities today, it is possible to quickly obtain building parameters in cities on a large scale, thus offering the possibility to study the risk flooding poses to urban buildings. To fill this research gap, taking Shanghai as an example, this study developed a new research framework to assess urban vulnerability based on vulnerability curves and online data of residential buildings. First, detailed information about residential buildings was prepared via web crawlers. Second, the cleaned residential building information fed a support vector machine (SVM) algorithm to classify the buildings into four flood vulnerability levels that represented the vulnerability curves of the four building types. Third, the buildings of different levels were given vulnerability scores by accumulating the depth–damage ratios across the possible range of flood depth. Further, combined with the unit price of houses, flood risk was assessed for residential buildings. The results showed that the F1-score for the classification of buildings was about 80%. The flood vulnerability scores were higher in both the urban center and the surrounding areas and lower between them. Since 1990, the majority of residential buildings in Shanghai have switched from masonry–concrete structures to steel–concrete structures, greatly reducing the vulnerability to floods. The risk assessment showed decreasing risk trend from the center outward, with the highest risk at the junction of the Huangpu, Jing’an and Xuhui districts. Therefore, this framework can not only identify the flood vulnerability patterns but also provide a clue for revealing the flood risk of residential buildings. With real estate data becoming increasingly accessible, this method can be widely applied to other cities to facilitate flood vulnerability and risk assessment.