Dispersion Of Debris Research Articles

Space Security and the Law of International Space Cooperation: The Need for Leadership and Coordination

In recent times space exploration and technological advancements hold prominent importance, the merger of space security and international collaboration must be paid attention too. Whereby, during the recent advancements in space technologies which include the proliferation of satellite and emergence of various space programs, the non-commercial and sustainable utilization of space must be taken care of. This paper explores and access the methodologies adopted and put into motion by nation having a well-established space program to address the difficulties faced while maintaining the space security along with ongoing space explorations. This research study will also pay emphasis towards analysing the already existing legal framework which directly governs various outer space activities, international organizations, role of governments and private industry players towards shaping of governance in outer space. In order to build trust and furthering the shared objectives in outer space and resolution of disputes among nation states, emphasis on how significant and valued international cooperation and diplomacy can prove to be. The various risks factors such as deliberate actions which are testing of anti-satellite weapons and dispersion of space debris in high volumes that the assets in space encounter are explored in this research. This study also discusses about case studies that have impacted the outer space and space explorations and other space missions positively as well as negatively in past instances. This study concludes the necessity of proactive leadership and teamwork in addressing the issue of space security and the legislation of international space cooperation. Roles of significant stakeholders, implementation of future course of actions with necessary changes to guide and provide policymakers in understanding the complexity of space reforms for peaceful utilization of outer space for both current and future human race.

The effect of ash, water vapor, and heterogeneous chemistry on the evolution of a Pinatubo-size volcanic cloud

Abstract. We employ the ECHAM5/MESSy2 atmospheric chemistry general circulation model (EMAC) that incorporates calculations of gas-phase and heterogeneous chemistry coupled with the ozone cycle and aerosol formation, transport, and microphysics to calculate the 1991 Pinatubo volcanic cloud. We considered simultaneous injections of SO2, volcanic ash, and water vapor. We conducted multiple ensemble simulations with different injection configurations to test the evolution of SO2, SO42-, ash masses, stratospheric aerosol optical depth, surface area density (SAD), and the stratospheric temperature response against available observations. We found that the volcanic cloud evolution is sensitive to the altitude where volcanic debris is initially injected and the initial concentrations of the eruption products that affect radiative heating and lofting of the volcanic cloud. The numerical experiments with the injection of 12 Mt SO2, 75 Mt of volcanic ash, and 150 Mt of water vapor at 20 km show the best agreement with the observation aerosol optical depth and stratospheric temperature response. Volcanic water injected by eruptive jet and/or intruding through the tropopause accelerates SO2 oxidation. But the mass of volcanic water retained in the stratosphere is controlled by the stratospheric temperature at the injection level. For example, if volcanic materials are released in the cold point above the tropical tropopause, most of the injected water freezes and sediments as ice crystals. The water vapor directly injected into the volcanic cloud increases the SO42- mass and stratospheric aerosol optical depth by about 5 %. The coarse ash comprises 98 % of the ash injected mass. It sediments within a few days, but aged submicron ash could stay in the stratosphere for a few months providing SAD for heterogeneous chemistry. The presence of ash accelerates the SO2 oxidation by 10 %–20 % due to heterogeneous chemistry, radiative heating, lofting, and faster dispersion of volcanic debris. Ash aging affects its lifetime and optical properties, almost doubling the ash radiative heating. The 2.5-year simulations show that the stratospheric temperature anomalies forced by radiative heating of volcanic debris in our experiments with the 20 km injection height agree well with observations and reanalysis data. This indicates that the model captures the long-term evolution and climate effect of the Pinatubo volcanic cloud. The volcanic cloud's initial lofting, facilitated by ash particles' radiative heating, controls the oxidation rate of SO2. Ash accelerates the formation of the sulfate layer in the first 2 months after the eruption. We also found that the interactive calculations of OH and heterogeneous chemistry increase the volcanic cloud sensitivity to water vapor and ash injections. All those factors must be accounted for in modeling the impact of large-scale volcanic injections on climate and stratospheric chemistry.

Retention and dispersion of buoyant plastic debris in a well-mixed estuary from drifter observations

Buoyant plastics enter estuaries largely from urban streams and an unknown fraction is retained before further transport to the open ocean. Plastic drifters were launched in a well-mixed estuary to simulate the movement of surface buoyant plastics. Two experiments were conducted, one during spring tides and one during neap tides, both with similar river flows and winds. Stronger tidal currents during spring tides resulted in larger dispersion and further downstream transport of the drifters. Half of the drifters were grounded within two tidal cycles. During the neap experiment, even more of the drifters (87%) were retained in the estuary. The grounding of such a high proportion of drifters suggests that much of the plastic pollution in estuaries of this type remains close to the riverine source. These findings imply that local clean-up programs removing grounded litter can reduce over half of the plastic pollution input to these estuaries.

Correlation And Dispersion Of Marine Debris To Mollusca In The Interidal Zone

The research was carried out on Langgur Beach from January to March 2021. The purpose of this study was to determine the correlation and dispersion of marine debris to molluscs in the Intertidal Zone of Langgur Beach, the edge of the Rosenberg Strait, Kei Islands, Indonesia. The data collection method of this research is the quadratic method. The results of the study noted that the total marine debris accumulated at 21 sampling points amounted to 7,596 items consisting of 14 categories of marine debris and 6 species of Mollusca were found. The results of the analysis show that the dispersion of surface marine debris and marine debris in the sediments are scattered in groups, the dispersion per type of macrozoobenthos on the surface and in the sediments is scattered in groups, regularly and randomly. The results of the analysis also showed a positive correlation between marine plastic debris on the sediment surface and the bivalves of Gafrarium pectinatum on the sediment surface.

Correlation And Dispersion Of Marine Debris To Mollusca In The Interidal Zone

The research was carried out on Langgur Beach from January to March 2021. The purpose of this study was to determine the correlation and dispersion of marine debris to molluscs in the Intertidal Zone of Langgur Beach, the edge of the Rosenberg Strait, Kei Islands, Indonesia. The data collection method of this research is the quadratic method. The results of the study noted that the total marine debris accumulated at 21 sampling points amounted to 7,596 items consisting of 14 categories of marine debris and 6 species of Mollusca were found. The results of the analysis show that the dispersion of surface marine debris and marine debris in the sediments are scattered in groups, the dispersion per type of macrozoobenthos on the surface and in the sediments is scattered in groups, regularly and randomly. The results of the analysis also showed a positive correlation between marine plastic debris on the sediment surface and the bivalves of Gafrarium pectinatum on the sediment surface.

Vessel routing optimization for floating macro-marine debris collection in the ocean considering dynamic velocity and direction

Floating macro-marine debris becomes a global environmental problem when emitted into the ocean. It damages the marine ecosystem, threatens human health, and also causes incalculable economic losses.Due to the impacts of ocean currents and winds, marine debris has been transported to different locations over time and time window cannot be ignored to navigate the locations of marine debris. To effectively mitigate the risk, we propose the vessel routing optimization with a time window to collect and remove marine debris. Ocean currents and winds also affect the velocity and direction of the collecting vessel. We first employ GNOME software to determine the debris trajectory and set a time window for each debris location. A mixed-integer nonlinear programming model considering vessel velocity is proposed to minimize the total debris collection cost. We propose two customized solution approaches: Branch-and-Cut (B&C) algorithm and two-stage Adaptive Large Neighborhood Search (ALNS) based heuristic algorithm to solve the proposed mathematical model in a reasonable timeframe. A computational study in waters off Boston is used to validate the proposed model and the solution algorithms. The result indicates that the average optimality gap for GUROBI and B&C algorithm is 17.53% and 10.52%, respectively, while this gap is only 3.44% for the ALNS algorithm. Moreover, the average computing time of the ALNS algorithm is roughly 24 and 17 times faster than that of the GUROBI and the B&C algorithm, respectively. The experimental results show that distance from debris location to the harbor is positively related to the collection cost and negatively related to the average usage of vessels’ capacity, and the dispersion of debris is also positively related to the fuel consumption of vessels.

Dispersion of debris during under water application of pulsed water jet device.

Dispersion of debris during under water application of pulsed water jet device.

Near-infrared nanosecond pulsed laser ablation of silver nanowire in aqueous media for low-power and low-debris laser processing

Silver nanowire (Ag NW) is used as an attractive alternative material to fabricate flexible transparent conductive electrodes (TCE) instead of indium tin oxide, which has brittle characteristics and unstable processing expenses. For practical applications of Ag NW TCE, a proper patterning process is essential because the Ag NW layer is usually formed from the solution process. Laser ablation is one of the promising patterning processes for fabricating Ag NW-based optoelectronic devices. Among the laser processes, the nanosecond near-infrared pulsed laser ablation (NIR PLA) is considered advantageous because it is cheaper than ultrashort or ultraviolet pulsed lasers and causes little damage to the flexible substrate. However, since the Ag NW absorbance in this wavelength is very low, laser processing of Ag NW can deteriorate processing quality due to the remaining debris that resulted from incomplete evaporation of Ag NW. In this study, we report NIR PLA of Ag NW in aqueous media that improved the processing results of Ag NW laser patterning. We found that effective debris removal with a low fluence was a result of advantages such as the reduced heat-affected zone and dispersion of silver nanoparticle debris in the liquid media. Under different processing parameters, the performance of patterned Ag NW improved in liquid media compared to the ambient condition. Significant improvements in the processing quality were also observed in the laser patterning of Ag NW on the flexible substrate without any degradation. Consequently, the patterned flexible Ag NW TCE was successfully fabricated via the proposed process.

Rapid protocol of dot-immunnoassay for orthopoxviruses detection

The aim of the work was to create a sensitive and fast immunochemical test for the detection of orthopoxviruses (OPXV) in the "point of care" format. This work presents the results of the comparative evaluation of a single-stage (rapid version) and two-stage protocol of dot-immunoassay based on plane protein array for detection of vaccinia virus (VACV), cowpoxvirus (CPXV) and ectromelia virus (ECTV) in viral culture materials with different degrees of purification. It has been established that rabbit polyclonal VACV-antibodies can be used in a one-stage dot-analysis, both as a capture agent immobilized on a substrate and as a detection reagent bound with colloidal gold particles. It is shown that the sensitivity of detection of OPXV is inversely related to the degree of purification of viruses. The one-stage variant of the dot-immunoassay allows reducing the analysis time to 39 min and increasing the detection sensitivity of all the studied orthopoxviruses in crude viral samples to a range of 104-103 PFU/mL. The increase in sensitivity in the rapid version of the analysis, presumably, occurs due to binding of capture antibodies to subviral structures that form large aggregates of gold particles. Ultrasonic treatment of culture virus reduces the detection sensitivity, presumably due to both the destruction of conformational epitopes located on the surface of subvirus structures, as well as the increase in the dispersion of cell debris, which limits diffusion and contacts of viral antigens with capture antibodies on the substrate. Both versions of the analysis are specific and do not detect interactions both with preparations of non-infected cell culture and with heterogeneous controls of the causative agents of erythematous infections. The rapid protocol of dot-immunnoassay described above can be used to detect, or help to exclude, the presence of threat viruses in samples and could be useful in a variety of biodefense applications. Ready-to-use setup, ease of analysis and the ability to visually accounting for results allow the test to be used outside of laboratories.

Frequency and composition of anthropogenic debris in the nests of sooty gulls Larus (Adelarus) hemprichii Bruch, 1853 from Sir Bu Na’ir Island, United Arab Emirates.

The proliferation and dispersion of marine debris results with various, often harmful, interactions with marine fauna. One such interaction, that is poorly investigated, is the incorporation of marine debris into the nests of seabirds, which at times results in hatchling entanglement. The objective of this study is to investigate the qualitative and quantitative aspects of marine debris used in the construction of the nests of sooty gulls Larus (Adelarus) hemprichii (Bruch, 1853) from Sir Bu Na’ir Island, United Arab Emirates. The numeric and gravimetric proportions of debris were documented following classification of type, color and presumed source. The results show that 11.2% of the 258 active nests examined contained debris. On average, nests included 2.0 ± 0.4 items of 6.1 ± 1.9 g mass. Non-plastic rubbish, particularly metals and glass, were the predominant debris utilized. The results reflect that sooty gulls frequently use anthropogenic debris as nesting materials in Sir Bu Na’ir Island.

Mixing of passive tracers at the ocean surface and its implications for plastic transport modelling

The tracking of virtual particles is one of the main numerical tools to understand the global dispersion of marine plastic debris and has been successful in explaining the global-scale accumulation patterns of surface microplastic, often called ‘garbage patches’. Yet, the inherent inaccuracies in plastic input scenarios and ocean circulation model results produce uncertainties in particle trajectories, which amplify due to the chaotic property of the surface ocean flow. Within this chaotic system, the subtropical ‘garbage patches’ correspond to the attractor. These facts make the large scale surface ocean circulation a mixing dynamical system, which means that the information of a particle’s initial location is lost over time. We use mixing entropy and Markov chain mixing of the transfer operator associated with surface ocean transport to quantify the time scales of mixing for the global surface ocean in each subtropical basin. In the largest parts of all basins we find mixing times in the order of or below 10 years, which is lower than typical simulation times for surface plastic transport simulations. Maximum mixing times of more than 10 years are found in some parts of the North and South Pacific. Our results have important implications for global dispersion modelling of floating materials on the basin scale: precise initial information has little relevance for long term simulations, and there is a temporal limit after which the backtracking of particles is not meaningful any more.

Strengthening mechanisms of aluminum matrix composite containing Cu-coated SiC particles produced by friction stir processing

ABSTRACTA friction stir processing (FSP) method has been developed to fabricate a locally reinforced aluminum matrix composite (AMC) by stirring electroless-copper-coated SiC particles into AA6061 matrix. The interfacial bonding between particulate reinforcement and the matrix was enhanced by the copper coating. Effective improvement in hardness and in tensile strengths has been proved. Microstructural investigation and analyses were conducted to correlate the microstructural evidences with the possible strengthening mechanisms. The effect of copper coating on the bonding between SiC particles and Al-matrix; the role of the dispersed Cu debris and the increased Cu content in solid solution on the strengthening; and the effect of friction stir on dislocation density and on the recrystallization behavior were analyzed. Multiple strengthening mechanisms due to diffusion between copper film and matrix; dispersion of fine copper debris and Al-Cu intermetallic compounds (IMCs) in the matrix; solid solution due to increased copper content and dislocation punching were four major mechanisms in interpreting the strengthening phenomena in AMC containing copper coated SiC reinforcements.

Prospective, Randomized Un-Blinded Three Arm Controlled Study in Coronary Artery Revascularization with Minimal Invasive Extracorporeal Circulation Systems (MiECC): Surrogate Parameter Analysis of Biocompatibility.

Minimal extracorporeal circulation techniques and systems (MiECC) may reduce the negative side effects of conventional extracorporeal circulation (ECC). However, it is still unclear as to what this is caused by, the reduced priming volume and hemodilution, or the avoidance of blood-air contact and dispersion of mediastinal debris into the systemic circulation. The aim of the trial was the comparison of MiECC to an open ECC setup (openECC) or a system with reduced blood air and debris interaction (closeECC).Methods: In a prospective randomized trial, 72 patients (73 ± 5.3 years; 83% male) referred for coronary artery bypass graft (CABG) were randomly assigned either to MiECC (priming volume 550mL), closeECC, or openECC (priming volume 1250mL). The laboratory surrogate endpoints (renal function, inflammatory response, ischemia, coagulation, and hemolysis) and clinical data were measured at six different time points (T1-6).Results: Patients were comparable for all preoperative variables. The operation times (MiECC 261 ± 79min; openECC 264 ± 75min; closeECC 231 ± 68min) and perfusion times (MiECC 115 ± 49min; openECC353 107 ± 37min; closeECC 99 ± 22min) revealed a trend of faster performance in the closeECC group (P < .05). Pro-inflammatory cytokines, ischemia, and coagulation markers were significantly elevated postoperatively in all cardiopulmonary bypass types, and decreased to pre-baseline levels at discharge (T5) without identifiable statistical differences between the three study groups. Free-hemoglobin was not significantly increased by centrifugal pump or cell saver procedures. Significant intraoperative hemodilution effects due to the different priming volumes were demonstrated only at the end of operation (T2) (MiECC Hb 9.6 ± 1.1g/dL; openECC Hb 9.0 ± 0.8g/dL; closeECC Hb 8.7 ± 1g/dL; P =. 01). Neither the hemodilution, suction technique (MiECC), nor blood-air interface (closeECC) could show sustainable benefits in this underpowered study, compared to conventional ECC systems (openECC) in a high volume series of surrogate parameters.

Environmental stress in the northern Tethys during the Paleogene: a review of foraminiferal and geochemical records from the Polish Outer Carpathians

During the Paleogene, the area of the northern Tethys was controlled by a turbidity system stimulated by diastrophic and geodynamic processes. These factors contributed to the dispersion and rapid oxygenation of organic debris. Its accumulation was a consequence of stagnant bottom water conditions that periodically occurred in the basin. In these periods, intense decomposition intensified by hydrothermal and diagenetic processes was associated with oxygen consumption and the release of greenhouse gases, which led to hypoxia and acidification. These phenomena intensified by thermal and density stratification had a major impact on the structure, evolution and distribution of biota. Stress associated with rapidly changing conditions induced by sedimentary process and upwelling resulted in the dominance of forms that colonized most sediments ( Glomospira, Ammodiscus, Recurvoides, Rzehakina) and surface waters ( Guembelitria, Chiloguembelina, Globanomalina, Globigerina, Cassigerinella, Catapsydrax ). At the time, foraminifera were limited to low-diversified eutrophic assemblages or were mainly replaced by siliceous phytoplankton (radiolarians and diatoms). Geochemical data confirm that environmental crises in the Paleogene basin took place under changing thermal conditions that reflect global events (KTBE, PTME, EEOC and TTE). Thermal stress favouring the formation of certain minerals or rocks occasionally occurred during the Paleocene to Eocene (siderite, phosphates) and dominated in the Early Oligocene (silica).

Discrete-element investigation of influence of granular debris flow baffles on rigid barrier impact

Granular debris flow baffles are commonly installed in front of rigid barriers to dissipate flow energy and reduce the required barrier impact capacity. Despite the engineering value of baffles, their influence on rigid barrier impact is still not well understood. A previously calibrated discrete element method (DEM) model using a series of flume experiments was adopted to study the effectiveness of installing baffles in front of a rigid barrier. Froude scaling was used to characterize the flow front. Different baffle configurations were examined, namely number of rows, spacing between successive rows (L), and baffle height. Results reveal an optimum row spacing of L/D = 3 (D is the slit size). Row spacing less than L/D = 3 leads to increased peak dynamic force from overflow impacting the barrier, whereas row spacing greater than L/D = 3 results in increased peak dynamic force from the granular debris flow front. Increasing spacing greater than L/D = 3 allows the dispersion of debris between rows and decreases the effectiveness of the second row. Adopting baffle heights greater than 1.5 times the approach flow depth (h) reveals little influence on the peak impact force induced on the barrier.

Who is the Bad Guy in Perfusion Technologies? Priming Volume, Blood Air Interaction or Pump Type: A Prospective, Randomized Trial of Three Different Techniques

Objectives: Minimal extracorporeal circulation techniques or circuits (MECC) may reduce the side effects of conventional extracorporeal circulation (CECC). However, it is unclear how much of this reduction is caused by reducing priming volume and hemodilution or by avoiding blood-air contact and dispersion of mediastinal debris into the systemic circulation.

The development of the pinnacles (Lena pillars) along Middle Lena (Sakha Republic, Siberia, Russia)

The study deals with the Lena Pillars (Sakha Republic, Russia, Siberia). The Lena Pillars are pinnacle features which are characteristic on karsts. The importance of these features is that they are extremely large and occur on very large areas. Their occurrence is interesting because they do not appear on tundra karst. We investigated the veneers of cliffs, the fracture density of the building rock, the distribution and dispersion of the fracture directions, direction distribution and dispersion of the giant grikes between the pillars, the layer thickness of the building rock, the size and dispersion of debris. We distinguished pillar types, and then we classified the features on the area of the pillars from a morphogenetical point of view. According to investigations and morphological analyses, the pillars developed from palaeokarsts. During the former karstification grikes and caverns developed close to the surface. These features coalesced into each other. The giant grikes of great size became filled and the pillars were covered. After the cut of the Lena River these features were revealed and became exhumed. Now the pillars are destroyed and continue developing by frost weathering.

Cassini observations reveal a regime of zonostrophic macroturbulence on Jupiter

In December 2000, the Cassini fly-by near Jupiter delivered high-resolution images of Jupiter’s clouds over the entire planet in a band between 50°N and 50°S. Three daily-averaged two-dimensional velocity snapshots extracted from these images are used to perform spectral analysis of jovian atmospheric macroturbulence. A similar analysis is also performed on alternative data documented by Choi and Showman (Choi, D., Showman, A. [2011]. Icarus 216, 597–609), based on a different method of image processing. The inter-comparison of the products of both analyses ensures a better constraint of the spectral estimates. Both analyses reveal strong anisotropy of the kinetic energy spectrum. The zonal spectrum is very steep and most of the kinetic energy resides in slowly evolving, alternating zonal (west–east) jets, while the non-zonal, or residual spectrum obeys the Kolmogorov–Kraichnan law specific to two-dimensional turbulence in the range of the inverse energy cascade. The spectral data is used to estimate the inverse cascade rate ∊ and the zonostrophy index Rβ for the first time. Although both datasets yield somewhat different values of ∊, it is estimated to be in the range 0.5–1.0×10−5m2s−3. The ensuing values of Rβ≳5 belong well in the range of zonostrophic turbulence whose threshold corresponds to Rβ≃2.5. We infer that the large-scale circulation is maintained by an anisotropic inverse energy cascade. The removal of the Great Red Spot from both datasets has no significant effect upon either the spectra or the inverse cascade rate. The spectral data are used to compute the rate of the energy exchange, W, between the non-zonal structures and the large-scale zonal flow. It is found that instantaneous values of W may exceed ∊ by an order of magnitude. Previous numerical simulations with a barotropic model suggest that W and ∊ attain comparable values only after averaging of W over a sufficiently long time. Near-instantaneous values of W that have been routinely used to infer the rate of the kinetic energy supply to Jupiter’s zonal flow may therefore significantly overestimate ∊. This disparity between W and ∊ may resolve the long-standing conundrum of an unrealistically high rate of energy transfer to the zonal flow. The meridional diffusivity Kϕ in the regime of zonostrophic turbulence is given by an expression that depends on ∊. The value of Kϕ estimated from the spectra is compared against data from the dispersion of stratospheric gases and debris resulting from the Shoemaker-Levy 9 comet and Wesley asteroid impacts in 1994 and 2009 respectively. Not only is Kϕ found to be consistent with estimates for both impacts, but the eddy diffusivity found from observations appears to be scale-independent. This behaviour could be a consequence of the interaction between anisotropic turbulence and Rossby waves specific to the regime of zonostrophic macroturbulence.

A statistical description of explosion produced debris dispersion

The handling of explosives and ammunition introduces a safety risk for personnel and third parties. Accidents related to storage, transport and transshipment may result in severe injury and material damage. Dispersion of structural debris is one of the main hazards resulting from detonations inside structures. Reliable prediction models for debris dispersion are essential for risk assessment methods.In this article we give a statistical description of the dispersion of explosion produced debris. The basis is a general expression for the projectile areal number density in the horizontal and vertical plane. Combined with engineering models for the launch conditions, predictions can be made. An analytical solution to the equations of motion may be used to allow for fast calculations. A parameter study shows consistent results. The model has been validated with internal detonation tests of bare charges in reinforced concrete structures. The validation clearly shows the prediction capabilities of the model for three loading regimes described in the literature.We give a thorough description of the validity and limitations of the model, and an outlook of current and future research. Examples are the failing debris mass distribution prediction for reinforced concrete in the shock overloading regime, and ricochet and roll and break-up at impact phenomena.

Dispersion of windborne debris

The dispersion of windborne debris that is caused by the object's aerodynamics and shape is investigated. It is shown that the flight may be divided into two phases. The initial phase, where the relative velocity is high and the rate of rotation low, is characterised by high transverse accelerations. The second phase, which has much lower accelerations, can be modelled as that of a compact object, where only the drag force is significant. The initial conditions for the second phase are determined by the initial phase. Approximate solutions to the equations of motion are proposed for rectangular plate and rod type debris. The results are is good agreement with wind tunnel observations.