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1.
Waste Manag ; 120: 687-697, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33199242

RESUMO

To achieve the goals of the circular economy, significant improvements in non-hazardous solid waste processing/treatment must be made. Large deficits in the digitalization of mechanical waste treatment plants (smart waste factory) offer great potential for improvement. Real-time material flow monitoring is carried out in very few plants, thus wasting considerable potential for improving plant performance. This article describes results from the authors' own practical analyses using sensor-based technologies for monitoring material flows, an on-site investigation in a large waste treatment plant and also in a pilot-scale plant (Technical Line 4.0) using mixed commercial waste (MCW) from Austria. The obtained data shows that the quantitative monitoring of volume and mass flow (via laser triangulation as well as near-infrared (NIR) based monitoring) and material composition (NIR sensor) is possible. The observed fluctuations were categorised in short-, mid- and long-term fluctuations and were led back to their causes, i.e. discontinuous feeding process, material and machine-specific characteristics. Using the quotient of the 90% (Q90) and 10% (Q10) quantiles of time-resolved volume-flow data for the assessment of fluctuations, for the considered time-intervals, resulted in Q90 / Q10 ratios between 3.39 and 4.58. If short-term fluctuations (within the observed time-intervals) are related to the 29.6 s moving average, deviations between 1.8% and 6.8% result. To verify the relevance of such fluctuations, sensor-based sorting (SBS) experiments were conducted, revealing a reduced product purity of 6% due to short-term fluctuations in the feed of the SBS-Machine using light packaging waste (LPW).


Assuntos
Eliminação de Resíduos , Gerenciamento de Resíduos , Áustria , Fenômenos Físicos , Embalagem de Produtos , Resíduos Sólidos
2.
Waste Manag ; 120: 290-302, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33333467

RESUMO

Household packaging waste sorting facilities consist of complex networks of processes to separate diverse waste streams. These facilities are a key first step to re-enter materials into the recycling chain. However, so far there are no general methods to predict the performance of such sorting facilities, i.e. how efficiently the heterogeneous packaging waste is sorted into fractions with value for further recycling. In this paper, a model of the material flow in a sorting facility is presented, which allows changing the incoming waste composition, split factors on the sorting units as well as the setup of the sorting facility. The performance of the sorting facility is judged based on the purity of the output material (grade) and the recovery of the input material. A validation of the model was performed via a case study on Belgian post-consumer packaging waste with a selection of typical waste items that can be found in this stream. Moreover, the model was used to predict the possible sorting qualities of future Belgian post-consumer packaging waste after an extension of the allowed waste packaging items in the waste stream. Finally, a sensitivity analysis was performed on the split factors, which are a key data source in the model. Overall, the developed model is flexible and able to predict the performance of packaging waste sorting facilities as well as support waste management and design for recycling decisions, including future design of packaging, to ensure proper sorting and separation.


Assuntos
Eliminação de Resíduos , Gerenciamento de Resíduos , Fenômenos Físicos , Plásticos , Embalagem de Produtos , Reciclagem
3.
Chemosphere ; 266: 129010, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33279241

RESUMO

A novel model is proposed to simulate radon migration by combining the fractal theory and the discrete fracture network (DFN) model. In the model, a power-law distribution based on fractal theory is applied to fracture length and aperture and the fracture locations and orientations are modeled with the Poisson distribution and von Mises-Fisher distribution, respectively. The model was applied to produce a computer code that can calculate the radon concentration, flux, and diffusivity of the fractured media. The key issues related to the model were analyzed and the results reveal that: (1) the threshold value of the ratio of the minimum fracture length to the maximum decreases as the fractal dimension of the fracture lengths and the relation between them follows an exponential law; (2) As the fractal dimension of the fracture lengths increases, more connected fractures are generated, resulting in a linear increase of the mean efficient radon diffusivity. (3) The dip angle is the parameter that has the greatest influence on radon migration in determining fracture orientations. (4) The radon exhalation rate increases exponentially with increasing advection velocity. (5) Models with larger fractal dimension for fracture lengths have larger representative elementary volume (REV) size and follow an exponential law.


Assuntos
Radônio , Poluentes Radioativos do Solo , Fractais , Fenômenos Físicos , Radônio/análise , Poluentes Radioativos do Solo/análise
4.
Chemosphere ; 2632021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33184521

RESUMO

The interfacial tracer test (ITT) conducted via aqueous miscible-displacement column experiments is one of a few methods available to measure air-water interfacial areas for porous media. The primary objective of this study was to examine the robustness of air-water interfacial area measurements obtained with interfacial tracer tests, and to examine the overall validity of the method. The potential occurrence and impact of surfactant-induced flow was investigated, as was measurement replication. The column and the effluent samples were weighed during the tests to monitor for potential changes in water saturation and flux. Minimal changes in water saturation and flux were observed for experiments wherein steady flow conditions were maintained using a vacuum-chamber system. The air-water interfacial areas measured with the miscible-displacement method completely matched interfacial areas measured with methods that are not influenced by surfactant-induced flow. This successful benchmarking was observed for all three media tested, and over a range of saturations. A mathematical model explicitly accounting for nonlinear and rate-limited adsorption of surfactant at the solid-water and air-water interfaces as well as the influence of changes in surface tension on matric potentials and flow was used to simulate the tracer tests. The independently-predicted simulations provided excellent matches to the measured data, and revealed that the use of the vacuum system minimized the occurrence of surfactant-induced flow and its associated effects. These results in total unequivocally demonstrate that the miscible-displacement ITT method produced accurate and robust measurements of air-water interfacial area under the extant conditions.


Assuntos
Ar/análise , Água/química , Adsorção , Benchmarking , Modelos Teóricos , Fenômenos Físicos , Porosidade , Tensão Superficial , Tensoativos/química
5.
Environ Pollut ; 267: 115458, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33254618

RESUMO

Considering the increasing use of Lithium (Li) and the necessity to fulfil this demand, labile Li occurrence in the environment will be enhanced. Thus, additional research is needed regarding the presence of this element in marine environment and its potential toxic impacts towards inhabiting wildlife. The aim of the present study was to evaluate Li toxicity based on the exposure of Mytilus galloprovincialis to this metal, assessing the biochemical changes related with mussels' metabolism, oxidative stress and neurotoxicity. For this, organisms were exposed to different Li concentrations (100, 250, 750 µg/L) for 28 days. The results obtained clearly demonstrated that Li lead to mussels' metabolism depression. The present study also revealed that, especially at the highest concentrations, antioxidant and biotransformation enzymes were not activated, leading to the occurrence of lipid peroxidation and loss of redox homeostasis, with increased content in oxidized glutathione in comparison to the reduced form. Furthermore, after 28 days, higher Li exposure concentrations induced neurotoxic effects in mussels, with a decrease in acetylcholinesterase enzyme activity. The responses observed were closely related with Li concentrations in mussels' tissues, which were more pronounced at higher exposure concentrations. Such results highlight the potential toxic effects of Li to marine species, which may even be higher under predicted climate changes and/or in the presence of other pollutants.


Assuntos
Mytilus , Poluentes Químicos da Água , Animais , Animais Selvagens , Biomarcadores , Dissulfeto de Glutationa , Peroxidação de Lipídeos , Lítio/toxicidade , Estresse Oxidativo , Fenômenos Físicos , Poluentes Químicos da Água/toxicidade
6.
Environ Pollut ; 267: 115573, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33254664

RESUMO

Despite the strong ability for complexation of heavy metals, a high amount of humic substances (HS) is always contained in membrane retentate from municipal solid waste landfill leachates treatment processes. Submerged Combustion Evaporation (SCE) can be used to effectively concentrate the membrane retentate. However, the impact of the SCE treatment on HS complexation capacity is still unclear. Since cadmium (Cd) plays a vital role in the pollution of soil and food, this study investigated the influence of the SCE treatment on the Cd complexation potential of leachate HS. Specific effects and complexation properties on Cd complexation of leachate HS before and after the SCE treatment were demonstrated using the Non-Ideal Competitive Adsorption model. The results showed that the Cd complexation capacity of carboxyl sites increased from 3.76 to 4.65 mol/kg-Total Organic Carbon (TOC) after the SCE treatment, which agreed with the stoichiometric number of proton binding sites. Moreover, characterization results indicated that SCE increased the affinity of HS for Cd by enhancing the overall aromaticity of HS (E2:E4 from 9.8 to 9.3), dominantly due to the humic acid contribution. By modeling the practical Cd remediation scenarios, the enhanced Cd complexation performance of HS after SCE treatment was observed even at low pH values (pH = 5) or insufficient TOC content (TOC = 50 mg/L).


Assuntos
Eliminação de Resíduos , Poluentes Químicos da Água , Cádmio , Substâncias Húmicas , Fenômenos Físicos , Resíduos Sólidos , Instalações de Eliminação de Resíduos
7.
Proc Natl Acad Sci U S A ; 117(44): 27148-27153, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-33060295

RESUMO

Probing the binding between a microbe and surface is critical for understanding biofilm formation processes, developing biosensors, and designing biomaterials, but it remains a challenge. Here, we demonstrate a method to measure the interfacial forces of bacteria attached to the surface. We tracked the intrinsic fluctuations of individual bacterial cells using an interferometric plasmonic imaging technique. Unlike the existing methods, this approach determined the potential energy profile and quantified the adhesion strength of single cells by analyzing the fluctuations. This method provides insights into biofilm formation and can also serve as a promising platform for investigating biological entity/surface interactions, such as pathogenicity, microbial cell capture and detection, and antimicrobial interface screening.


Assuntos
Aderência Bacteriana/fisiologia , Análise de Célula Única/métodos , Ressonância de Plasmônio de Superfície/métodos , Biofilmes , Fenômenos Biofísicos , Técnicas Biossensoriais , Microscopia de Força Atômica , Fenômenos Físicos , Propriedades de Superfície
8.
J Food Sci ; 85(11): 3885-3898, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33063351

RESUMO

Although the ice phase greatly influences the properties of ice cream, other structural components also affect its rheological behavior, particularly after melting. In this study, mix viscosity (serum phase viscosity), extent of fat destabilization (FD), and overrun were manipulated to produce different microstructures. The effects of these structural components were evaluated on the rheological properties of the ice creams and melted ice creams. In oscillatory thermorheometry, mix viscosity and then overrun, influenced G' and tanδ below -10 °C. When ice phase decreased (between -10 and -2.7 °C), mix viscosity had reduced effects, but continued to strongly affect G' and tanδ, followed by FD, and with lower effects from overrun. When the ice phase was completely melted at 0 °C, FD had most influence on G' and tanδ, followed by overrun, and with lower effects from mix viscosity. In creep/recovery test, six-element model described well creep behavior of melted ice cream at 0 °C. Viscous behavior at lower shear rate (η0 0 °C) was most influenced by mix viscosity, followed by FD, and lower overrun effects. In stress growth measurement, transient behavior, represented by σY 0 °C, of melted matrix at 0 °C was most influenced by FD, followed by mix viscosity, with lower overrun effects. In flow ramp measurement, Hysteresis Area was most affected by mix viscosity, followed by overrun, and with lower FD effects. Moreover, correlation between Hyst 0 °C and tanδ Peak suggested that structure formation affected the magnitude of tanδ Peak. These results document the importance of microstructure on properties of melted ice cream. PRACTICAL APPLICATION: The understanding of how structural components, such as mix viscosity, fat destabilization, and overrun, affect the ice cream matrix can help manufacturers to control its rheological behavior. The influence of these structural components on the G', tanδ, η0 0 °C , σY 0 °C , and Hyst 0 °C can be also used to understand the structural rearrangements that occur in meltdown tests and sensory analyses for future studies. Therefore, elucidation of these mechanisms on the rheological properties can directly assist in quality control and new product development in the ice cream industry.


Assuntos
Sorvetes/análise , Leite/química , Animais , Bovinos , Congelamento , Fenômenos Físicos , Reologia , Viscosidade
9.
Proc Natl Acad Sci U S A ; 117(44): 27218-27223, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-33067388

RESUMO

Most proteins have evolved to spontaneously fold into native structure and specifically bind with their partners for the purpose of fulfilling biological functions. According to Darwin, protein sequences evolve through random mutations, and only the fittest survives. The understanding of how the evolutionary selection sculpts the interaction patterns for both biomolecular folding and binding is still challenging. In this study, we incorporated the constraint of functional binding into the selection fitness based on the principle of minimal frustration for the underlying biomolecular interactions. Thermodynamic stability and kinetic accessibility were derived and quantified from a global funneled energy landscape that satisfies the requirements of both the folding into the stable structure and binding with the specific partner. The evolution proceeds via a bowl-like evolution energy landscape in the sequence space with a closed-ring attractor at the bottom. The sequence space is increasingly reduced until this ring attractor is reached. The molecular-interaction patterns responsible for folding and binding are identified from the evolved sequences, respectively. The residual positions participating in the interactions responsible for folding are highly conserved and maintain the hydrophobic core under additional evolutionary constraints of functional binding. The positions responsible for binding constitute a distributed network via coupling conservations that determine the specificity of binding with the partner. This work unifies the principles of protein binding and evolution under minimal frustration and sheds light on the evolutionary design of proteins for functions.


Assuntos
Sequência de Aminoácidos/genética , Ligação Proteica/genética , Proteínas/genética , Fenômenos Biofísicos , Cinética , Modelos Moleculares , Fenômenos Físicos , Conformação Proteica , Dobramento de Proteína , Proteínas/química , Termodinâmica
10.
Proc Natl Acad Sci U S A ; 117(42): 26091-26098, 2020 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-33020279

RESUMO

We have demonstrated the effectiveness of reinforcement learning (RL) in bluff body flow control problems both in experiments and simulations by automatically discovering active control strategies for drag reduction in turbulent flow. Specifically, we aimed to maximize the power gain efficiency by properly selecting the rotational speed of two small cylinders, located parallel to and downstream of the main cylinder. By properly defining rewards and designing noise reduction techniques, and after an automatic sequence of tens of towing experiments, the RL agent was shown to discover a control strategy that is comparable to the optimal strategy found through lengthy systematically planned control experiments. Subsequently, these results were verified by simulations that enabled us to gain insight into the physical mechanisms of the drag reduction process. While RL has been used effectively previously in idealized computer flow simulation studies, this study demonstrates its effectiveness in experimental fluid mechanics and verifies it by simulations, potentially paving the way for efficient exploration of additional active flow control strategies in other complex fluid mechanics applications.


Assuntos
Algoritmos , Simulação por Computador , Meio Ambiente , Aprendizagem/fisiologia , Modelos Biológicos , Reforço Psicológico , Humanos , Fenômenos Físicos
11.
Proc Natl Acad Sci U S A ; 117(43): 26550-26552, 2020 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-33024019
12.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 984-987, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018150

RESUMO

This paper presents a signal analysis approach to identify the contact objects at the tip of a flexible ureteroscope. First, a miniature triaxial fiber optic sensor based on Fiber Bragg Grating(FBG) is devised to measure the interactive force signals at the ureteroscope tip. Due to the multidimensional properties of these force signals, the principal components analysis(PCA) method is introduced to reduce dimensions. The signal features are then extracted from the representative principal component signals using the wavelet transform(WT) method. Experimental results show that the contact objects at the tip of a ureteroscope are readily discriminated from the measured force signals with the proposed approach.Clinical Relevance-This work commits to analyze the contact force signals at the tip of a flexible ureteroscope for the purpose of contact objects identification.


Assuntos
Fenômenos Mecânicos , Ureteroscópios , Tecnologia de Fibra Óptica , Fenômenos Físicos , Análise de Ondaletas
13.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2279-2282, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018462

RESUMO

Simulations that are meant to determine the steady-state distribution of a diffusible solute such as oxygen in tissues have typically used finite difference methods to solve the diffusion equation. Finite difference methods require a tissue mesh with enough points to resolve oxygen gradients near and between discrete blood vessels. The large number of points that are typically required can make these calculations very slow. In this paper, we investigate a numerical method known as the Green's function method which is not bound by the same constraint. The Green's function method is expected to yield an accurate oxygen distribution more quickly by requiring fewer mesh points. Both methods were applied to calculate the steady state oxygen distribution in a model simulation region. When the Green's function calculation used meshes with 1/2, 1/4 and, 1/8 of the resolution required for the finite-difference mesh, there was good agreement with the finite difference calculation in all cases. When the volume of the domain was increased 8-fold the Green's function method was able to calculate the O2 field in 22 minutes, whereas the finite difference calculation is expected to take approximately 1 week. The number of steps required for the Green's function calculation increases quadratically with the number of points in the tissue mesh. As a result, small meshes are calculated very quickly using Green's functions, while for larger mesh sizes this method experiences a significant decrease in efficiency.


Assuntos
Algoritmos , Oxigênio , Cor , Difusão , Fenômenos Físicos
14.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4318-4321, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018951

RESUMO

This paper investigates the effectiveness of four Huffman-based compression schemes for different intracortical neural signals and sample resolutions. The motivation is to find effective lossless, low-complexity data compression schemes for Wireless Intracortical Brain-Machine Interfaces (WI-BMI). The considered schemes include pre-trained Lone 1st and 2nd order encoding [1], pre-trained Delta encoding, and pre-trained Linear Neural Network Time (LNNT) encoding [2]. Maximum codeword-length limited versions are also considered to protect against overfit to training data. The considered signals are the Extracellular Action Potential signal, the Entire Spiking Activity signal, and the Local Field Potential signal. Sample resolutions of 5 to 13 bits are considered. The result show that overfit-protection dramatically improves compression, especially at higher sample resolutions. Across signals, 2nd order encoding generally performed best at lower sample resolutions, and 1st order, Delta and LNNT encoding performed best at higher sample resolutions. The proposed methods should generalise to other remote sensing applications where the distribution of the sensed data can be estimated a priori.


Assuntos
Compressão de Dados , Redes Neurais de Computação , Fenômenos Físicos
15.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4506-4509, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018995

RESUMO

Smart devices are quickly becoming ubiquitous with the rise of portable biosensors and the internet of things. There exists particular interest in enhancing common objects to have smart capabilities and finding inexpensive solutions for diagnostic tools. One such example is transforming paper items into interactive devices and point-of-care analytic products. Due to the lightweight, flexible, and cost-efficient qualities of paper, unobtrusively powering these devices remains an outstanding problem. In this paper, we demonstrate an electrostatic human-touch powered energy harvesting system, integrated with flexible painted conductive electrodes on paper. This system harvests 8.5 nJ of energy and reaches a voltage of 1.3 V on a 10 nF energy storage capacitor. This technology not only provides a method of powering paper-based products with routine human gestures but can also detect human touch for input communication to sensors.


Assuntos
Eletrônica , Condutividade Elétrica , Eletrodos , Humanos , Fenômenos Físicos , Eletricidade Estática
16.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4648-4651, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019030

RESUMO

Myocardial Infarction (MI) is a fatal heart disease that is a leading cause of death. The silent and recurrent nature of MI requires real-time monitoring on a daily basis through wearable devices. Real-time MI detection on wearable devices requires a fast and energy-efficient solution to enable long term monitoring. In this paper, we propose an MI detection methodology using Binary Convolutional Neural Network (BCNN) that is fast, energy-efficient and outperforms the state-of-the- art work on wearable devices. We validate the performance of our methodology on the well known PTB diagnostic ECG database from PhysioNet. Evaluation on real hardware shows that our BCNN is faster and achieves up to 12x energy efficiency compared to the state-of-the-art work.


Assuntos
Infarto do Miocárdio , Dispositivos Eletrônicos Vestíveis , Eletrocardiografia , Humanos , Infarto do Miocárdio/diagnóstico , Redes Neurais de Computação , Fenômenos Físicos
17.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4758-4761, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019054

RESUMO

Human-robot interactions help in various industries and enhance the user experience in different ways. However, constant safety monitoring is needed in environments where human users are at risk, such as rehabilitation therapy, space exploration, or mining. One way to improve safety and performance in robotic tasks is to include biological information of the user in the control system. This can help regulate the energy that is delivered to the user. In this work, we estimate the energy absorbing capabilities of the human arm, using the metric Excess of Passivity (EOP). EOP data from healthy subjects were obtained based on Forcemyography of the subjects' arm, to expand the sources of biological information and improve estimations.Clinical relevance- This protocol can help determine the ability of rehabilitation patients to withstand robotic stimulation with high amplitudes of therapeutic forces, as needed in assistive therapy.


Assuntos
Braço , Robótica , Humanos , Miografia , Fenômenos Físicos
18.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 5016-5020, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019113

RESUMO

INTRODUCTION: Our primary goal was to evaluate the performance of a new high-efficiency electric fence energizer unit using resistive load changes. Our secondary goal was to test for compliance with the classical energy limits and the newer charge-based limits for output. METHODS: We tested 4 units of the Nemtek Druid energizer with 2 channels each. We used a wide load-resistance range to cover the worst-case scenario of a barefoot child making a chest contact (400 Ω) up to an adult merely touching the fence (2 kΩ). RESULTS: The energy output was quite consistent between the 8 sources. Even at the lowest resistance, 400 Ω, the outputs were well below the IEC 60335-2-76 limit of 5 J/pulse. The charge delivered was also quite consistent. Even at the lowest resistance, 400 Ω, the outputs (679 ± 23 µC) were well below the proposed limits of 4 mC for short pulses. CONCLUSIONS: The high-efficiency electric fence energizers satisfied all relevant safety limits. Charge, energy, voltage, and current outputs were consistent between channels and units.


Assuntos
Eletricidade , Adulto , Criança , Frequência Cardíaca , Humanos , Fenômenos Físicos
19.
PLoS One ; 15(10): e0237264, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33002034

RESUMO

The precise evaluation of the potential damage caused by large commercial aircraft crash into civil structures, especially nuclear power plants (NPPs), has become essential design consideration. In this study, impact of Boeing 767 against rigid wall and outer containment building (reinforced concrete) of an NPP are simulated in ANSYS/LS-DYNA by using both force time history and missile target interaction methods with impact velocities ranging from 100 m/s to 150 m/s. The results show that impact loads, displacements, stresses for concrete and steel reinforcement, and damaged elements are higher in case of force time history method than missile target interaction method, making the former relatively conservative. It is observed that no perforation or scabbing takes place in case of 100 m/s impact speed, thus preventing any potential leakage. With full mass of Boeing 767 and impact velocity slightly above 100 m/s, the outer containment building can prevent local failure modes. At impact velocity higher than 120 m/s, scabbing and perforations are dominant. This concludes that in design and assessment of NPP structures against aircraft loadings, sufficient thickness or consideration of steel plates are essential to account for local failure modes and overall structural integrity. Furthermore, validation and application of detail 3D finite element and material models to full-scale impact analysis have been carried out to expand the existing database. In rigid wall impact analysis, the impact forces and impulses from FE analysis and Riera's method correspond well, which satisfies the recommendations of relevant standards and further ensure the accuracy of results in full-scale impact analysis. The methodology presented in this paper is extremely effective in simulating structural evaluation of full-scale aircraft impact on important facilities such as NPPs.


Assuntos
Acidentes Aeronáuticos , Aeronaves , Liberação Nociva de Radioativos , Acidentes Aeronáuticos/estatística & dados numéricos , Códigos de Obras , Simulação por Computador , Materiais de Construção/estatística & dados numéricos , Análise de Elementos Finitos , Humanos , Imageamento Tridimensional , Fenômenos Mecânicos , Modelos Teóricos , Centrais Nucleares , Fenômenos Físicos , Liberação Nociva de Radioativos/prevenção & controle , Liberação Nociva de Radioativos/estatística & dados numéricos , Aço , Colapso Estrutural/prevenção & controle , Colapso Estrutural/estatística & dados numéricos
20.
PLoS One ; 15(10): e0237563, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33021984

RESUMO

In the development of ship anchorage training systems, the problems of low efficiency and poor fidelity exist in the simulation of flexible anchor chains, and a position-based dynamics (PBD) method is proposed to express the chain movement. To satisfy the requirements of simulating anchoring manipulation, the PBD method modifies the position of anchor chain particles by controlling constraints. Using the original distance constraint and bending constraint of the PBD approach, two novel constraints, namely, the long-range attachment (LRA) constraint and pin constraint, are developed to simulate the bending and stretching of the anchor chain. Simulation of ordinary ropes can be achieved using distance and bending constraints. The developed LRA constraint is capable of preventing anchor chain particles from being overstretched. Adoption of the pin constraint is proposed to integrate two particles into one to be calculated as an attempt to simulate the connection between the chain and the anchor. The continuous collision detection (CCD) constraint method considering friction and viscosity is used to detect collisions in the ship anchoring training system. Collision detection covers chain collisions with other objects and chains. Finally, the PBD method is more efficient and robust than the Newton method. Since it has sufficient visual plausibility and can realize real-time visualization, the simulation system developed by the PBD method effective for training crew members.


Assuntos
Navios , Algoritmos , Simulação por Computador , Humanos , Fenômenos Físicos , Navios/instrumentação , Navios/estatística & dados numéricos , Treinamento por Simulação
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