Debris Impact Research Articles

Plastisphere on microplastics: In situ assays in an estuarine environment

In this study, the influence of the plastisphere on metals accumulation and weathering processes of polystyrene (PSMPs) and nylon microplastics (NyMPs) in polluted waters during a 129 day-assay were studied. MPs were characterized through scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX), X-ray diffraction (XRD), attenuated total reflectance Fourier transformed infrared (ATR-FTIR) spectroscopy, contact angle, and thermogravimetric analysis (TGA). Also Cr, Mn, Zn, Cd, Pb, and Cu in the plastisphere on MPs were analyzed during the assay. Potentially pathogenic Vibrio, Escherichia coli, and Pseudomonas spp. were abundant in both MPs. Ascomycota fungi (Phona s.l., Alternaria sp., Penicillium sp., and Cladosporium sp.), and yeast, were also identified. NyMPs and PSMPs exhibited a decrease in the contact angle and increased their weights. SEM/EDX showed weathering signs, like surface cracks and pits, and leaching TiO2 pigments from NyMPs after 42 days. XRD displayed a notorious decrease in NyMPs crystallinity, which could alter its interaction with external contaminants. Heavy metal accumulation on the plastisphere formed on each type of MPs increased over the exposure time. After 129 days of immersion, metals concentrations in the plastisphere on MPs were in the following order Cr ˃ Mn ˃ Zn ˃ Cu ˃ Pb ˃ Cd, demonstrating how the biofilm facilitates metal mobilization. The results of this study lead to a better understanding of the impact of marine plastic debris as vectors of pathogens and heavy metals in coastal environments.

A Shared Vision on the 2004 Indian Ocean Tsunami in Malaysia: Hazard Assessments, Post-Disaster Measures and Research

The tsunami is one of the deadliest natural disasters, responsible for more than 260,000 deaths and billions in economic losses over the last two decades. The footage of the devastating power of the 2004 Indian Ocean tsunami perhaps remains vivid in the memory of most survivors, and Malaysia was one of the countries affected by the unprecedented 2004 tsunami. It was the first time the Malaysian government had managed such a great disaster. This review, therefore, gathers the relevant literature pertaining to the efforts undertaken following the event of the 2004 tsunami from Malaysia’s perspective. A compilation of post-event observations regarding tsunami characteristics is first presented in the form of maps, followed by building damage, including damage modes of wall failure, total collapse, debris impact and tilting of structures. In addition, hazard assessments and projections regarding a hypothetical future tsunami towards vulnerable hazard zones in Malaysia are reviewed. It is observed that future tsunami risks may originate from the Indian/Burma Plate, Andaman Island, Sunda Trench, Manila Trench, Sulu Trench, Negro Trench, Sulawesi Trench, Cotabato Trench and Brunei slide. A rundown of post-2004 measures and tsunami research undertaken in the country is also included in this review, serving as a reference for disaster management globally. Overall, the outcomes of this review are important for understanding tsunami vulnerability and the resilience of coastal infrastructures, which will be crucial for continued progress in the future.

Distribution and Abundance of Marine Debris on Intertidal Zone at Three Selected Small Islands, Sabah

The issue of marine debris has become worldwide attention since it occurs almost everywhere globally Thus, it is crucial to focus on this area to sustain the life below the water as stated by United Nations (SDG 14). This study evaluated the distribution, abundance, and composition of marine debris in three selected islands at Sabah namely Manukan, Mamutik and Sapi Islands. Marine debris was identified according to its categories as stated by the Department of Environment (DOE). The study was carried out to compare the waste abundance of three islands since the different beach types represent various activities that produce debris. The sampling design was conducted with two plot areas plotted and observed on each island for three consecutive weeks. Based on the assessment done, Mamutik Island recorded the most abundance of marine debris with 12.185 kg (66.2%) of debris found followed by Manukan Island with 5.487 kg (29.8%) of debris and Sapi Island with 0.746 kg (4.1%). It was observed that plastic debris especially plastic bags, plastic bottles, plastic straws, general plastics, polystyrene, and plastic cups were the main contributors to marine debris pollution. While among all the three islands studied, Sapi Island is considered the cleanest and smallest Island compared to others since the location of this island is quite far from the mainland. The solid and waste management on each island has been identified in order to formulate a new strategy to reduce the impact of marine debris on the intertidal zone especially on human health and the environment. These studies have provided a clear understanding of the distribution of marine debris in these islands. Several recommendations and suggestions have been listed to reduce and prevent marine debris pollution.

Hybrid Shielding for Hypervelocity Impact of Orbital Debris on Unmanned Spacecraft

The passive shielding of space craft structures is critical due to the increase in demand for lightweight protection, which is required to counter the damaging effects of micro-meteoroid orbital debris (MMOD) on unmanned spacecraft, which have steeply increased in recent years. Research on hypervelocity impact (HVI) led to the development of shield configurations such as the conventional Whipple shield, which consists of two plates separated by a stand-off distance to allow for the fragmentation and dispersion of the debris from the impact. Variations in the Whipple shield have been proposed, where additional layers are included for increased energy dissipation efficiency. In this work, the authors develop, validate and test a numerical model of an orthogonally loaded hybrid Whipple shield, incorporating an aluminium honeycomb core, orientated with hexagonal tubes perpendicular to the direction of proposed debris travel, to mitigate the well-known channelling effect. The debris threat is an A2024-T3 projectile, impacting the structure at a velocity of 6.5 km/s. The proposed model is validated with experimental observations of the debris spread at half-angle and the efficiency of the proposed topology is assessed against a conventional two-plate A2024-T3 shield. The honeycomb core cell density, its position relative to the point of impact, the thickness of the honeycomb shell, and the material of the honeycomb are thoroughly analysed. A hybrid honeycomb structure concept is proposed, which provides a highly efficient alternative to a standard Whipple shield design, without significantly compromising the weight of the structure. The obtained results clearly show that the hybrid Whipple shield exhibits significantly increased the kinetic energy dissipation of the debris from the impactor and shield front plate, with an increase in the dissipated kinetic energy that can reach 86.8% relative to the conventional shield.

Experimental and Numerical Investigation of Floating Large Woody Debris Impact on a Masonry Arch Bridge

Masonry arch bridges form an essential part of existing transport infrastructure around the world, including mainland Europe and the northeastern US. Recent extreme flood events highlight that masonry arch bridges spanning watercourses are vulnerable to flood-induced hydrodynamic and debris impact loads. When the flow interacts with the bridge superstructure, with or without discrete floating debris, a complex interaction is observed. This paper presents both experimental and numerical studies to investigate this complex phenomenon, including fluid–structure and structure–structure interactions. A typical single-span masonry arch bridge and large woody debris representing a tree log are investigated. Experimental observations from a scaled hydraulic model, with and without debris in the flow, are first presented for the case where the abutment of the bridge is fully submerged. Next, the capability of the numerical method smoothed particle hydrodynamics (SPH) in simulating the hydrodynamic behaviour and debris impact observed in the experiment is discussed. Following this, both hydrodynamic and debris-induced pressure–time histories on the bridge are obtained using the SPH model. Results reveal that the debris impact leads to a significantly more localised load on the bridge compared to the situation with hydrodynamic load only.

Study of dynamic debris impact load on flexible debris-resisting barriers and the dynamic pressure coefficient

The use of steel flexible barriers to mitigate landslide risk on natural hillsides is becoming common in the past decade in Hong Kong. The current design approach for this kind of barrier structure involves the adoption of the hydrodynamic load model to predict dynamic impact forces, followed by non-linear structural analyses of flexible barriers using numerical programs based on the pseudo-static force method. From local design guidelines, the dynamic pressure coefficient, a critical input parameter in the hydrodynamic load model, is taken as 2.0. This empirically considers the effect of impacts from boulders up to 2.0 m in diameter. With a view to rationalising the design approach, a series of physical impact tests and numerical analyses was conducted to investigate the dynamic debris impact on flexible barriers and the resulting barrier response. The physical impact tests involved up to 9 m3 of debris resisted by a 1.5 m high steel ring-net barrier. The tests were conducted in the 28 m long large-scale flume facility at the Kadoorie Centre in Hong Kong. Numerical modelling using computer programs LS-DYNA and NIDA-MNN was conducted to analyse the dynamic response of flexible barriers with different structural forms. The study aims to evaluate the dynamic pressure coefficient and to verify the current design approach based on the suggested dynamic pressure coefficient from this study. Results indicate that a dynamic pressure coefficient of 1.0 is, in general, appropriate for design purposes if the debris comprises primarily water and fine-grained particles.

Forecasting the stranded area of marine debris in Indonesian coasts using mobidrift model and floating drifter

The problem of marine debris became a concern of world scientists that placed Indonesia as the second contributor of the world. Plastic litter that leaked from the land and came through the river is a major source of Indonesia marine debris. This marine debris is a serious threat for ocean and coastal ecosystems. The Ministry of Marine Affairs and Fisheries of Indonesia supports the Presidential Regulation to reduce the plastic litter to 70% by 2025 by developing numerical modeling of marine plastic litter trajectory. Using a user-friendly web portal interface, we can simulate the trajectory of marine plastic litter from different points of source at different seasons. Wind, current, and tide data were used to force the particle on the simulation. The result of the model was compared with the record of the real time movement of twenty drifters that were released from three rivers mouth. The development of this trajectory model will become a useful tool to provide the information of the movement of marine debris in Indonesian sea waters and beyond. Knowing the path and stranded location in each season will improve our policy of planning and mitigate the impact of marine debris.

Experimental Study of Micrometeoroids Impacts on an X-Ray Telescope Model using Micro-pore Optics and CMOS Detector with Micron-sized Particles

This laboratory study aimed to assess the potential damage caused by the impact of micrometeoroids or space debris on a novel X-ray focusing telescope composed of Micro-pore Optics (MPO) plates and Complementary Metal Oxide Semiconductor (CMOS) sensors. An impact experiment was conducted on a simplified model of an X-ray telescope composed of two MPO plates and one CMOS sensor. The diameters of the projectiles we used are 1 ∼ 50 μm. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS) are methods for investigating the morphology of the impact craters and analyzing the composition of residues. We described the impact crater morphology on both MPO plates and CMOS chips. Results of impact craters size and number show that one 1 μm particle produces a damaged area of 18 μm2 in aluminum (Al) film of the MPO plate on average (at a median speed of 2 km s−1), resulting in 10 light leak spots on the CMOS chip. Meanwhile, one particle with a diameter of 50 μm may damage 3 micropores (about 7 × 10−3 mm2) on the MPO plate at a median speed of 6 km s−1. About 1.5 particles could cause one bad pixel on the CMOS chip behind the MPO plates. Nevertheless, no failure of the CMOS sensor or severe damage to the MPO device was observed after the impact.

Modeling and Analysis of Non-Linear Phenomena of Satellite Power System in Space Environment and Hazard-Risk Evaluations

With the aim to solve the problem of the non-linear phenomenon of the satellite power system under the influence of the space environment factors, which threatens the stability of the power system, in this paper, the abnormal charging and discharging of solar arrays and solar array drive assembly (SADA) induced by the space plasma environment and accidental events, such as debris impact, and the non-linear behaviors of the solar array and load during the Earth eclipse are modeled and analyzed. On this basis, the hazard risk evaluations of the above non-linear phenomena are carried out, and the weak links of the satellite power system in the space environment are identified. The results show that the unexpected energy of the solar array will increase the current stress and power loss of the power device, resulting in S3R over-regulation. An SADA arc fault will reduce the power supply capacity of the solar array, damage the shunt regulator, and affect the quality of the bus. The non-linear behavior of the solar array and load during the Earth eclipse may damage the battery charge and discharge regulator, seriously affecting the stability of the power system.

Impact resistance mechanism of reactive material bumper for spacecraft Whipple shield: Experiments and numerical simulations

With the rapid development of human manned spaceflight, the threat of hypervelocity impact of space debris to spacecraft safety has attracted more and more attention, and new materials for spacecraft shield need to be developed to meet the challenges caused by explosive growth of space debris. In this paper, the experiments of projectiles with hypervelocity impact on the Whipple shields with reactive material as bumpers were carried out by using two-stage light-gas gun. Through numerical simulations and experiments, the interaction between projectile and reactive material bumper was studied, and the fragments distribution, velocity and temperature of debris cloud induced by projectile impacting on reactive material bumper were analyzed. The hypervelocity impact resistance mechanism of Whipple shield with reactive material as bumper was obtained. The results show that the impact and detonation reaction combined effect of reactive material bumper can cause the projectile to be subjected to shock wave load twice, which leads to more effective fragmentation of projectile, more effective dispersion and deceleration of debris cloud, and more effective temperature rise of material. Reactive material bumper can improve the protective capability of Whipple shield, and has a great potential application prospect.

A fully coupled hydrodynamic-DEM model for simulating debris dynamics and impact forces

Many post-event field investigations suggest that dramatic flood hydrodynamics and impact of large floating objects contribute significantly to building damage during a tsunami event. However, the interactions between the transient flood waves, floating debris, and structures have neither been well explored nor understood, and few modelling tools have been developed to simulate these complex interactive processes, especially when multiple debris are involved. This paper introduces a novel fully coupled modelling system, based on a high-performance 2D hydrodynamic model and a 3D discrete element method (DEM) model, for simulating the movement of multiple debris carried along by highly convective flows and directly quantifying the induced impact forces on structures. The proposed model is applied to reproduce a series of physical experiments, and the results agree well with the experimental measurements. It is demonstrated that the newly coupled modelling system can capture the interaction between the fluid, debris of different shapes and sizes and structures, making it suitable for real-world applications. The model provides a new robust tool for simulating the extreme hazards caused by tsunamis or flash flooding and assessing their risk, and therefore has the potential to be useful for planning and designing disaster risk reduction schemes in those at-risk areas.

Structure and activity of marine bacterial communities responding to plastic leachates

Plastic in the ocean releases organic compounds that are able to enter the marine dissolved organic carbon pool and be utilized by heterotrophic bacteria. However, no information is known about which groups of bacteria are able to grow and degrade plastic leachates. Here we characterized a marine bacterial community from the NW Mediterranean Sea growing on plastic leachates and quantified its total activity. We used two petro-based plastics, low density polyethylene (LDPE) and polystyrene, and one biodegradable plastic, polylactic acid (PLA), to generate leachates under irradiated (UV–Vis) and non-irradiated conditions. Then we incubated them with a natural bacterial inoculum and determined the single-cell activity and associated taxonomy of the bacterial groups, using a combination of Catalyzed Reporter Deposition-Fluorescence In Situ Hybridization (CARDFISH) and BioOrthogonal Non-Canonical Amino acid Tagging (BONCAT). The community growing in the leachates was mainly composed of Alteromonas (Gammaproteobacteria), followed by Roseobacter (Alphaproteobacteria) and unclassified Gammaproteobacteria. Overall, marine bacteria in the irradiated treatments showed higher total activity compared to the non-irradiated ones, with the community growing on LDPE's leachates presenting the highest values. The biodegradable PLA leachates presented lower activity than those from petro-based plastics but similar bacterial composition, suggesting that it is possible that PLA could last in the ocean as much as petro-based plastics do. The results from this study show the impact of marine plastic debris in the marine microbial community and the marine carbon cycle.

Fragility functions for highway RC bridge under various flood scenarios

Bridges are a country's lifeline infrastructure. As a result of climate change and global warming, floods are becoming more frequent and unpredictable. Even well-designed bridges are vulnerable to extreme flooding, as recent flood events have demonstrated. Flood fragility curves are developed for an existing RC rail over bridge considering various loading scenarios such as flood level up to the top of the pier, flood level up to the top of the girder, the impact due to log and debris, the effect of providing shear key and the effect due to scouring. The threshold mean flood velocities for the initiation of serviceability limit state for the above flood scenarios are found out. When there is no shear key, the exceedance probability for the deck displacement is found to increase with the flood water level. This increase is found to be about 92% at a particular mean flood velocity of 8.6 m/s, when the floodwater level increases from 3/4th the height of the girder to the full height of the girder. Typical log impact and debris impact increase the vulnerability of the bridge by about 45% and 80%, respectively, for a particular flood velocity of 6.8 m/s and when the flood level is up to the full height of the girder. The fragility of the bridge increases by about 80% for a scour depth of about 1.5 m at a mean flood velocity of 8.6 m/s.

Numerical study of the resistance of heat pipes to space debris impact

Numerical study of the resistance of heat pipes to space debris impact

Effect of structure orientation and debris initial orientation on peak debris loading during tsunami: An experimental and numerical investigation

The impact of the debris during extreme events is one of the major factors that has to be accounted for the critical design of the coastal structures. This study, investigates the effect of peak impact load due to combination of debris and the hydraulic bore on a structure with varying orientation angles. The bore profile is generated by using dam-break condition and a shipping container that is based on the ISO criteria fitted with an accelerometer, is used as a debris in this study. The peak impact load due to the combination of debris and the bore is measured by the multi-axial load cell that is mounted at the bottom of the modelled structure. It is observed that the orientation angle of the structure plays a major role in identifying the peak debris impact load. Therefore, a new coefficient of orientation angle, ‘Cθ’ is proposed to modify the basic impulse-momentum equation; that accounts for the excess loads on the structure. The experimental study is reproduced and simulated using particle based numerical method ‘δ-SPH’ and the results are validated with experimental observations. Further, the δ-SPH model is used to carry out detailed parametric study by varying the debris mass.

A Framework to Model the Wind-Induced Losses in Buildings during Hurricanes

Wind-induced loss modeling plays a key role in insurance risk management. Hence, a flexible vulnerability framework is to be developed for residential and commercial buildings. This model predicts the losses induced by hurricane wind pressure, wind-borne debris and wind-driven rain. Twenty-five different key variables of the buildings and environment are used as attributes for the simulations. Model results are validated using the Florida Public Hurricane Loss Models (FPHLM) and HAZUS wind vulnerability functions. New contributions include (1) a Markovian roof-aging model to address decreases in roof performance due to aging, and (2) occupancy-specific interior value models based on FEMA Normative quantities for the systematic evaluation of interior value applicable to archetype buildings. A simple wind debris impact model and wind-driven rain intrusion model is also introduced. The influence of the number of stories, roof aging, and window vulnerability resulting in damage are investigated in this article to ensure consistency of the results. The proposed framework enables insurance loss modelers to make judicious choices of input variables based on partial or detailed knowledge about the building to model losses. Future research should focus on validation and calibration using good-quality insurance claims data.

Asynchronous Synergistic Damage Effect of Atomic Oxygen and Space Micro Debris on Kapton Film

In the low earth orbit environment, many environmental factors lead to the degradation of material properties. The synergistic effect of long-term atomic oxygen (AO) irradiation and instantaneous impact of micro debris (MD) on long-term and transient space environmental factors has attracted more and more attention. In this paper, the performance evolution of Kapton films under the conditions of MD, AO single factor load spectrum and MD + AO, AO + MD asynchronous synergistic load spectrum were studied by laser driven flyer and microwave atomic oxygen technology. The macro morphology, optical properties and quality changes of Kapton films before and after each load spectrum were compared, and the mechanism of micro morphology and structure changes was explored. The results show that compared with MD + AO loading spectrum, the surface holes of Kapton films are larger under AO + MD load spectrum condition, the residual aluminum particles formed by reverse sputtering of Al particles during impact are less, the average transmittance of the film decreases slightly, and the weight loss of Kapton film is slightly more under the same atomic oxygen exposure time. Under the condition of MD + AO load spectrum, plastic tearing cracks, craters and holes are formed on the surface of Kapton film; the edge of the hole formed under the condition of AO + MD load spectrum is straight, without obvious depression and tear characteristics. Under the condition of MD + AO load spectrum, due to the adhesion of Al after the impact of micro debris, the subsequent atomic oxygen erosion of the film is reduced, so the C-C bond is not seriously damaged, and a considerable part of the residual aluminum flyer is oxidized to alumina by atomic oxygen; The AO + MD loading spectrum test makes the film first eroded by atomic oxygen, resulting in the reduction in C–O bond and C–C bond. The fracture of C–N bond is caused by the hypervelocity impact of micro debris. Hypervelocity impact leads to the thermal decomposition of the material, destroys the C–N bond in the imide ring and generates an N–H bond. This study will provide a method reference and a reference for the multi-factor ground collaborative simulation of space environment of spacecraft materials.

A framework for estimating water ingress due to hurricane rainfall

Hurricanes can have adverse effects on residential communities and pose a significant risk to their economic prosperity. The ingress of water into a building due to wind-driven rain (WDR) and inland flooding can cause significant damage leading to downtime or temporary loss of housing. Existing frameworks focus on estimating the amount of water ingress due to WDR and inland flooding separately. This paper provides a comprehensive framework that considers both WDR and inland flooding when estimating the amount of water ingress into residential buildings due to hurricane rainfall. The framework estimates the water ingress due to WDR by combining the WDR intensity with the perforated area of the building envelopes. The intensity of the WDR is quantified using an Eulerian Multi-phase Model. The buildings’ envelope is considered susceptible to damage from the impact of windborne debris and excessive dynamic wind pressure. The framework to characterize and quantify inland flooding uses a coupled hydrologic-hydrodynamic model to estimate the inundation depth at each building. A case study consisting of a residential community in Houston, TX, which is subject to Hurricane Harvey illustrates the ability of the framework to capture the influence of WDR and inland flooding when quantifying water ingress.

Exogenous windborne debris: Definition and required extent of surrounding buildings for modeling in hurricanes

Modeling and estimating the damage to the built environment caused by hurricane winds is an essential requirement to enhance community resilience. Consideration of damage to a building’s envelope caused by windborne debris impact is necessary. To model this damage for a certain subdivision of houses, debris generated in neighboring subdivisions, defined as exogenous debris, must be taken into account. Existing physics-based damage estimation models do not consider the effect exogenous windborne debris has on the estimated damage due to hurricane winds. This paper provides a methodology to identify the extent of the neighboring subdivisions that needs to be considered during damage simulation to accurately account for exogenous windborne debris. The presented methodology is based on first identifying the extent of the neighboring subdivisions through a simulation-based strategy which follows an iterative scheme. For each size increment, the iterative scheme estimates the number of exogenous windborne debris using a physics-based damage estimation model. The single building solution is then generalized to a subdivision of any arbitrary shape. The proposed methodology is applied to analyze a hypothetical residential community in Miami, FL. Analysis results show the effect on the required extent of the neighboring subdivisions of the hurricane maximum wind speed, the floor-area ratio and the resistance of the building envelope components. The analysis concludes with a regression model that can be used to estimate the size of the neighboring subdivisions to be used in damage estimation models.

Mitigation of Tsunami Debris Impact on Reinforced Concrete Buildings by Fender Structures

Buildings located in coastal regions are prone to tsunami dangers, which often carry debris in the form of shipping containers and boats. This paper presents an approach for the design of fender structures to minimize debris impacts on buildings. The impact of shipping containers, which are categorized as large debris, is considered in the study. Since the weights of shipping containers are standardized, the impact energy can be related to other debris. For a fender structure, cone-type rubber fenders are used to resist the impact of the shipping container. Various fender reactions are considered as parameters to study the efficiency of the fenders. The displacement-controlled nonlinear static analysis is carried out to determine the building capacity. The energy approach for shipping container impact is used to evaluate the resistance of the building. Capacity curves, energy absorptions, inter-story drift ratios of the buildings with and without a fender structure, and the efficiency of the fender are presented. The buildings with a fender structure can absorb the energy from the impact of a loaded shipping container. Conversely, the building without a fender structure cannot resist the impact of a loaded shipping container. From the obtained results, a recommendation is given for buildings with a fender structure. The hydrodynamic force on the fender structure is transferred to the main building through the fender. Hence, the yield force of the fenders affects the performance of the main building that must be considered in the design.