Dynamic Analysis Research Articles

Design and Optimization of NR-Based Stretchable Conductive Composites Filled with MoSi2 Nanoparticles and MWCNTs: Perspectives from Experimental Characterization and Molecular Dynamics Simulations.

Stretchable conductive composites play a pivotal role in the development of personalized electronic devices, electronic skins, and artificial implant devices. This article explores the fabrication and characterization of stretchable composites based on natural rubber (NR) filled with molybdenum disilicide (MoSi2) nanoparticles and multi-walled carbon nanotubes (MWCNTs). Experimental characterization and molecular dynamics (MD) simulations are employed to investigate the static and dynamic properties of the composites, including morphology, glass transition temperature (Tg), electrical conductivity, and mechanical behavior. Results show that the addition of MoSi2 nanoparticles enhances the dispersion of MWCNTs within the NR matrix, optimizing the formation of a conductive network. Dynamic mechanical analysis (DMA) confirms the Tg reduction with the addition of MWCNTs and the influence of MoSi2 content on Tg. Mechanical testing reveals that the tensile strength increases with MoSi2 content, with an optimal ratio of 4:1 MoSi2:MWCNTs. Electrical conductivity measurements demonstrate that the MoSi2/MWCNTs/NR composites exhibit enhanced conductivity, reaching optimal values at specific filler ratios. MD simulations further support experimental findings, highlighting the role of MoSi2 in improving dispersion and mechanical properties. Overall, the study elucidates the synergistic effects of nanoparticles and nanotubes in enhancing the properties of stretchable conductive composites.

Strengthening-Durable Trade-Off and Self-Healing, Recyclable Shape Memory Polyurethanes Enabled by Dynamic Boron-Urethane Bonds.

Addressing the demand for integrating strength and durability reinforcement in shape memory polyurethane (SMPU) for diverse applications remains a significant challenge. Here a series of SMPUs with ultra-high strength, self-healing and recyclability, and excellent shape memory properties through introducing dynamic boron-urethane bonds are synthesized. The introducing of boric acid (BA) to polyurethane leading to the formation of dynamic covalent bonds (DCB) boron-urethane, that confer a robust cross-linking structure on the SMPUs led to the formation of ordered stable hydrogen-bonding network within the SMPUs. The flexible crosslinking with DCB represents a novel strategy for balancing the trade-off between strength and durability, with their strengths reaching up to 82.2MPa while also addressing the issue of durability in prolonged usage through the provision of self-healing and recyclability. The self-healing and recyclability of SMPU are demonstrated through rapid dynamic exchange reaction of boron-urethane bonds, systematically investigated by dynamic mechanical analysis (DMA). This study sheds light on the essential role of such PU with self-healing and recyclability, contributing to the extension of the PU's service life. The findings of this work provide a general strategy for overcoming traditional trade-offs in preparing SMPUs with both high strength and good durability.

The impact of boron carbide in soft and hard body armor: A comprehensive evaluation on Kevlar and UHMWPE fabrics

AbstractIn this research, an investigation was conducted to ascertain the impact of boron carbide (B4C) microparticles on soft and hard armor configurations, utilizing two distinct high‐performance fabrics namely, Kevlar and Ultra‐high Molecular Weight Polyethylene (UHMWPE), also this work discerned the optimal fabric for protection against dagger attacks and 9 mm full metal jacket (FMJ) projectiles. Initially, rheological tests on four shear thickening fluid (STF) samples revealed that 70% of nano‐silicate (SiO2) content was the optimal ratio. Besides, scanning electronic microscope (SEM) tests showed that B4C affected the nano‐silicate dispersion. Hence, the use of STF as a matrix, led to complete protection in low‐velocity stab test and behavior improvement when subjected to NIJ ballistic test for both fabric types. On the other hand, the dynamic mechanical analysis (DMA) of the thermosetting epoxy resin‐based composites reinforced by B4C indicated that the 10% ratio offered maximum rigidity, resulting in improved ballistic performance. This study revealed that Kevlar fabrics exhibit superior behavior in soft protection, while UHMWPE hard composite display further rigidity against high‐velocity impacts. Overall, this work contributes novel insights into the efficiency of B4C integration within soft and hard armor configurations using two ballistic fabrics, highlighting their performance characteristics in ballistic shielding.Highlights Investigation of B4C microparticles: The research examines the impact of B4C microparticles on soft and hard armor configurations. High‐performance fabrics: Kevlar and UHMWPE uses. The use of STF as a matrix for soft and thermosetting epoxy resin for hard armor: enhanced composite performance. Low‐velocity and high‐velocity impact tests investigations; microparticles B4C incorporation: superior mechanical characteristics. Remarkable energy absorption: promising shielding uses.

Seismic Performance Assessment of Conventional Construction and Ductile Concrete Moment Frames Using Performance-Based Unified Procedure

A Performance-Based Unified (PBU) procedure has recently been proposed by the National Research Council Canada (NRC) to systematically evaluate seismic design requirements available in the National Building Codes (NBC) of Canada. Conventional Construction reinforced Concrete Moment-resisting Frame (CC-CMF) and Ductile reinforced Concrete Moment-Resisting Frame (D-CMF) systems were used in this paper to first assess the proposed PBU procedure and second determine the adequacy of the basis for seismic design requirements in NBC and see its performance margin against different structural performance levels. Results indicate that the detailed screening in the PBU procedure efficiently reduces the number of Incremental Dynamic Analyses (IDA) by more than 60% for CC-CMF while providing remarkable accuracy. It was also found that the CC-CMF system designed for the Normal importance category can provide an adequate margin against Life Safety (LS) performance level objectives, while the D-CMF system designed for the same importance category passes the Collapse Prevention (CP) performance level criteria.

The Derivation of Vertical Damping Reduction Factors for the Design and Analysis of Structures Using Acceleration, Velocity, and Displacement Spectra

Damping reduction factors (DRFs) play a vital role in the seismic design of structures. DRFs have been widely studied due to their primary importance to the lateral resistance of structures subjected to earthquakes. On the other hand, devastating earthquakes have occurred all over the world, and recently, the Kahramanmaraş earthquakes in Turkey revealed the import of the vertical component of earthquakes and their impact on structures and infrastructures. Considering the importance of this parameter, this paper aims to develop new damping reduction factor (DRF) equations for the acceleration (DRFa), velocity (DRFv), and displacement spectra (DRFd) of the vertical components of earthquakes. For this purpose, 775 real ground motion records were selected from the Pacific Earthquake Engineering Research (PEER) strong motion database, and the vertical elastic response spectra of selected records were computed according to linear dynamic analysis. Taking the 5%-damped vertical response spectra as the target, the vertical spectral damping reduction factors (DRFa, DRFv, and DRFd) were computed for 1%, 3%, 10%, 15%, 20%, 30%, and 40% damping ratios. The effect of the earthquake magnitude, distance, and soil types on the DRFs was investigated. The results indicated that magnitude, distance, and soil type had no particular effect on the trend in the DRFs. Based on the evaluations, extensive statistical analyses were carried out, and new prediction equations were developed according to the nonlinear regression method. The developed equations were then compared to those found in the literature and seismic design codes. The comparisons proved that the proposed DRFa, DRFd, and DRFv models are strongly compatible with real DRFs and show strong robustness compared to existing models.

Editorial for JEC Volume 3 Issue 1 (2024)

This editorial introduces the first issue of the third volume of the Journal of Edge Computing (JEC). It provides an overview of the five articles featured in this issue, which cover diverse applications of edge computing technologies in domains such as cybersecurity, healthcare, and distributed systems. The first article summarizes the 4th Edge Computing Workshop (doors 2024), highlighting research advances in edge computing. The second article proposes an LSTM-based model for detecting cyber attacks in IoT systems using the CIC-IoT2023 dataset. The third article presents a machine-learning model for classifying respiratory system sounds to aid in the early diagnosis of respiratory diseases. The fourth article describes an IoT system that analyzes environmental data using geolocation to generate alerts about potential health risks. The fifth article explores the use of telemetry for dynamic analysis of distributed systems to identify architectural smells and anomalies. The editorial highlights the potential of edge computing technologies in addressing various challenges and expresses gratitude to the authors, reviewers, and editorial team for their contributions.

Molecular Dynamics Analysis of Adhesive Forces between Silicon Wafer and Substrate in Microarray Adhesion

With the development of the electronics industry, the requirements for chips are getting higher and higher, and thinner and thinner wafers are needed to meet the processing of chips. In this study, a model of the adhesion state of semiconductor wafers in the stacking–clamping process based on microarray adsorption was established, the composition adhesion was discussed, the microarrays of different materials and pressures were experimentally studied, and a molecular dynamics model was established. The molecular dynamics analysis showed that the adhesion force was only related to the type of atom, and the applied pressure did not change the adhesion force. According to the simulation results, the tangential adhesion between the metal and the wafer is greater than that between the ceramic and the wafer, the adsorption force between the aluminum–magnesium alloy and the silicon wafer is shown in the normal direction, and the repulsion force between other materials and the silicon wafer is shown in the normal direction. During the pressure process, the metal is in the elastic deformation stage between the metal and the wafer, the wafer is plastically deformed in the silicon carbide ceramic and wafer, and the wafer is elastically deformed in the alumina ceramic and wafer. In this paper, the adhesion between the substrate and the wafer is studied, a method of constructing microarrays to enhance adhesion is proposed, and the tangential deformation of the array unit under pressure is studied, which provides theoretical support for increasing the adhesion by constructing microarrays.

Determination of dynamic collapse limit states using the energy-based method for multi-story RC frames subjected to column removal scenarios

The Alternative Load Path method is widely adopted to perform progressive collapse analyses for reinforced concrete (RC) frame structures subjected to column removal scenarios. Considering that the progressive collapses are usually dynamic phenomena, nonlinear dynamic analyses can yield the most accurate results. However, the associated computational cost is high. Alternatively, the energy-based method (EBM) can be employed to efficiently calculate the maximum dynamic responses. Unfortunately, collapse or dynamic limit states (DLS) cannot be directly determined when the EBM is adopted for the progressive collapse analyses, because it is essentially a quasi-static approach. To tackle this issue, in this paper an EBM-Intersection Point-based (EBM-IP-based) method is proposed to effectively determine the DLS. The method is considering that the dynamic instability will occur once the dynamic capacity curve exceeds the corresponding static capacity curve. Hence, it is possible to determine the DLS by making a correction on the intersection point of the aforementioned two curves without performing nonlinear dynamic time-history analyses. Compared with the other energy components, the kinetic energy at the moment of the peak displacement response is relatively small and the effectiveness of the EBM is verified. Through both static pushdown analyses and incremental dynamic analyses for 48 column removal scenarios of six different multi-story RC frames, the effectiveness of the proposed EBM-IP-based method is verified and the associated coefficients are calibrated. Statistical information and (joint) probabilistic density functions (PDF) of the coefficients are identified. Further, stochastic analyses are carried out in order to quantify the model uncertainties when adopting the EBM-IP-based method. On the basis of all the calculation results, a Gumbel distribution is adopted to capture the PDF of the model uncertainty in relation to displacements, while a lognormal distribution is adopted to fit the PDF of the model uncertainty in terms of resistances. Moreover, a multi-variate Gaussian distribution model with two components is employed to fit the joint PDF.

Phytochemical Profile, Antioxidant, Enzyme Inhibition, Acute Toxicity, In Silico Molecular Docking and Dynamic Analysis of Apis Mellifera Propolis as Antidiabetic Supplement.

This study aims to identify the phytochemical profile of Apis mellifera propolis and explore the potential of its anti-diabetic activity through inhibition of α-amylase (α-AE), α-glucosidase(α-GE), as well as novel antidiabetic compounds of propolis. Apis mellifera propolis extract (AMPE) exhibited elevated polyphenol 33.26±0.17 (mg GAE/g) and flavonoid (15.45±0.13 mg RE/g). It also indicated moderate strong antioxidant activity (IC50 793.09±1.94 μg/ml). This study found that AMPE displayed promising α-AE and α-GE inhibition through in vitro study. Based on LC-MS/MS screening, 18 unique AMPE compounds were identified, with majorly belonging to anthraquinone and flavonoid compounds. Furthermore, in silico study determined that 8 compounds of AMPE exhibited strong binding to α-AE that specifically interacted with its catalytic residue of ASP197. Moreover, 2 compounds exhibit potential inhibition of α-GE, by interacting with crucial amino acids of ARG315, ASP352, and ASP69. Finally, we suggested that 2,7-Dihydroxy-1-(p-hydroxybenzyl)-4-methoxy-9,10-dihydrophenanthrene and 3(3-(3,4-Dihydroxybenzyl)-7-hydroxychroman-4-one as novel inhibitors of α-AE and α-GE. Notably, these compounds were initially discovered from Apis mellifera propolis in this study. The molecular dynamic analysis confirmed their stable binding with both enzymes over 100 ns simulations. The in vivo acute toxicity assay reveals AMPE as a practically non-toxic product with an LD50 value of 16,050 mg/kg. Therefore, this propolis may serve as a promising natural product for diabetes mellitus treatment.

Numerical Modeling and Dynamic Response Analysis of an End-Anchored Floating Bridge With a Damaged Pontoon Under Repair Operation

Abstract Floating bridges face potential hazards due to ship collisions throughout their operational lifetime. In a situation where a pontoon is significantly damaged from an accident, a floating drydock may be used to compensate for the lost buoyancy and provide a dry atmosphere for operations. As the repair might take months, a primary concern is whether the repair can be in-site conducted without shutting down the road traffic. This study aims to investigate the feasibility of using a drydock for the repair. The numerical model of the in-operation damaged bridge is established for a comparative dynamic analysis with the intact end-anchored bridge. Eigenvalue analysis is conducted, and pendulum modes of oscillation are found with an eigen-period of around 15 s. The dynamic responses are analyzed through a series of fully coupled time-domain simulations under various environmental conditions. The results indicate that the standard deviation of the moment about the girder weak axis increases significantly at the damaged pontoon axis due to the excitation of low-frequency resonant response. Swell wave loads might induce dynamic amplification to the damaged bridge, even with a relatively small wave height. In addition, the internal stress of the bridge girder is investigated and found to be larger, especially, at the lower locations of the cross section. It is suggested that the responses can be managed by limiting the excitation of pendulum modes or providing special damping devices in practical engineering.

A Mathematical Analysis of Competitive Dynamics and Aggressive Treatment in the Evolution of Drug Resistance in Malaria Parasites

Experimental evidence supports the counterintuitive notion that rapid eradication of pathogens within a host, infected with both drug-sensitive and -resistant malaria parasites, can actually accelerate the evolution of drug-resistant pathogens. This study aims to analyze the competitive dynamics between these two strains through a mathematical model and evaluate the impact of aggressive treatment on the spread of drug resistance. We conducted equilibrium, uncertainty, and sensitivity analyses to assess the model, identifying and measuring the influence of key factors on the outcome variable (the population of drug-resistant parasites). Both equilibrium and local sensitivity analyses concurred that the density of drug-resistant parasites is notably affected by genetic instability, the production rate of red blood cells, the number of merozoites, and competition factors. Conversely, there is a negative relationship between genetic instability and one of the competition coefficients. Global sensitivity analysis offers a comprehensive examination of the impact of each input parameter on the temporal propagation of drug resistance, effectively accounting for the interplay among parameters. Both local and global sensitivity analyses underscore the continuous impact of drug treatment on the progression of drug resistance over time. This paper anticipates exploring the underlying mechanisms of drug resistance and providing theoretical support for developing more effective drug treatment strategies.

Hydrogen bonding heterogeneity correlates with protein folding transition state passage time as revealed by data sonification

Protein-protein and protein-water hydrogen bonding interactions play essential roles in the way a protein passes through the transition state during folding or unfolding, but the large number of these interactions in molecular dynamics (MD) simulations makes them difficult to analyze. Here, we introduce a state space representation and associated "rarity" measure to identify and quantify transition state passage (transit) events. Applying this representation to a long MD simulation trajectory that captured multiple folding and unfolding events of the GTT WW domain, a small protein often used as a model for the folding process, we identified three transition categories: Highway (faster), Meander (slower), and Ambiguous (intermediate). We developed data sonification and visualization tools to analyze hydrogen bond dynamics before, during, and after these transition events. By means of these tools, we were able to identify characteristic hydrogen bonding patterns associated with "Highway" versus "Meander" versus "Ambiguous" transitions and to design algorithms that can identify these same folding pathways and critical protein-water interactions directly from the data. Highly cooperative hydrogen bonding can either slow down or speed up transit. Furthermore, an analysis of protein-water hydrogen bond dynamics at the surface of WW domain shows an increase in hydrogen bond lifetime from folded to unfolded conformations with Ambiguous transitions as an outlier. In summary, hydrogen bond dynamics provide a direct window into the heterogeneity of transits, which can vary widely in duration (by a factor of 10) due to a complex energy landscape.

A Framework for Rapidly Predicting the Dynamics of Flexible Solar Arrays in the China Space Station with a Verification Based on On-Orbit Measurement Data

The Chinese space station is a complex structure with large flexible appendages. Obtaining the on-orbit response characteristics of such a structure under different working conditions is a traditional and classic challenge in the field of dynamics. To address the on-orbit dynamics of the China Space Station, the basic equations for dynamic reduction, assembly and data recovery of linear and nonlinear substructures are derived based on the reduction and recovery theory, and a fast coupling analysis framework for flexible systems with nonlinear attachments is formed. This coupling analysis framework is adopted to quickly acquire the dynamic response of the China Space Station during in-orbit operation, thereby guiding the design. Taking SZ-15 radial docking to the Chinese Space Station as the object, the substructure of six nonlinear flexible arrays is reduced, the full flexible dynamic equation of the space station is assembled, and the response of each part of the flexible wing during the docking process is analyzed and recovered. By designing a reasonable and reliable flexible wing test scheme in-orbit, the acceleration at the root and top of the flexible wing during the docking of SZ-15 is obtained. The measured data in-orbit show that the acceleration analysis results of the typical parts of the flexible wing have a good agreement, which verifies the correctness of the fast coupling analysis framework of the flexible system. Hence, the dynamic coupling characteristics analysis of the main structure of the space station and the flexible wing based on this method can better guide the rationality of the design of the dynamic characteristics of the Chinese Space Station.

Molecular dynamics simulation of stretching-induced ductility for polystyrene

Some glassy polymers have a mechanical behavior that stretching can induce the brittle-to-ductile transition (BDT). For polystyrene (PS) film, after pre-stretching above glass transition temperature (Tg), the property at room temperature transforms to ductile, showing higher elongation at break and higher yield strength. In this work, we have investigated this phenomenon of stretching induced ductility by molecular dynamics (MD) analysis referring to our experimental findings. PS specimens in united-atom model with different chain lengths were loaded by deformation at two-step temperature setting, which was 393 K at first and then 300 K, to simulate tensile behaviors with various per-stretching conditions. The result has shown that as deformations beginning at 393 K and proceeding at 300 K, root mean square radius of gyration (Rg) and the degree of orientation (P2,x) reach the maximum value higher than solely stretching at 393 K or 300 K. Therefore, the stretching-induced BDT is attributed to changing of both chain conformation and coil configuration in polymer chains in stepwise stretching, which can change their coil configuration at the pre-stretching, adjusting their chain network in a more stretchable position, leading the whole polymer amorphous from brittle to ductile. The simulation result is accordant with our experiment and previous BDT theory to glassy polymers.

An Experimental Study of the Properties of Carbon Fiber/Epoxy Composites Mixed with Rubber Granules

In this research work, the mechanical properties of hybrid composites reinforced with woven carbon fiber mats particulated with natural rubber powders as fillers in the epoxy resin matrix were investigated. The specimens were prepared by the hand-layup process followed by a vacuum bag moulding process. The vacuum moulding reduces the voids or cavities in the hybrid composites. The natural rubber powder was added in different weight proportions (5%, 10%, 15%, and 20%), and carbon fiber is added in 20% for all the specimens. Experiments such as tension testing, flexural testing, water absorption/acid corrosion/base corrosion tests, dynamic mechanical analysis (DMA), and scanning electron microscopic (SEM) analysis were conducted to evaluate the epoxy carbon rubber (ECR) composites. The tensile and flexural test findings demonstrated that the addition of 10% natural rubber particles gave better results as compared with other proportions. The water/acid/base absorption test findings reveal that the ECR composites are not affected by water/acid/base. The DMA teat findings show that ECR composites having 10% natural rubber have higher damping factor, storage, and loss modulus. The SEM analysis shows that ECR hybrid composites with 10% rubber particles contained a uniform distribution of rubber particles over reinforcement, and also, there were no cracks and voids. According to this research findings, ECR hybrid composites with 10% natural rubber particles prepared during the vacuum bag moulding process can be used to prepare aerospace interior components.

Characterization of surface and bulk properties of α-Tocopherol blended and γ irradiated UHMWPE sandwich nanocomposites

In the present study, an unconventional approach in compression molding is chosen to fabricate Ultra High Molecular Weight Polyethylene (UHMWPE) sandwich composites with Graphene (Gr) and Nano-diamond (ND) as fillers. A unique comparison is done between the surface and bulk properties of UHMWPE nano-composites and UHMWPE sandwich composites. Influence of gamma irradiation at doses of 50, 100 kGy doses and vitamin E (vit-E) on crystal structure, mechanical, thermal and tribological characteristics of UHMWPE composites were studied through x-ray diffraction (XRD), raman spectroscopy, dynamic mechanical analysis (DMA), rheology, differential scanning calorimetry (DSC), tensile, nano-indentation and wear characterization techniques. Fracture regions and surface wear of the samples were analysed through scanning electron microscopy (SEM) to understand the dispersion behavior of fillers in matrix. The concentration of vit-E content in UHMWPE greatly influenced the crosslinks and surface properties in gamma irradiated composites. Gamma irradiation have shown significant improvement in crystallinity, viscous behavior and bulk properties of UHMWPE composites. Irradiated UHMWPE nano-composites have shown better tensile results when compared with sandwich composites, with 22 % increase in young's modulus and 16 % increase in yield stress. Wear rate has been reduced by 25 % for irradiated sandwich UHMWPE composites when compared with UHMWPE nano-composites.

Antiviral potential of rosuvastatin and hesperidin in combination with favipiravir liposomal nanoformulations in targeting the main protease (Mpro) of SARS-CoV-2: Molecular docking, molecular dynamics and in-vitro studies

Favipiravir (Fav) is a drug utilized to treat coronavirus disease 2019 (COVID-19) due its capacity to expedite the clearance of the SARS-CoV-2 virus through binding to its main protease (Mpro). However, the use of Fav has been associated with some adverse health effects. Meanwhile, numerous studies have highlighted the potential antiviral activities of specific phytochemicals and statins. Consequently, we thought to explore drug combination strategies involving certain statins and phytochemicals and their liposome nanoformulations either alone or with Fav, aiming to augment its efficacy and mitigate potential adverse effects. The molecular docking and molecular dynamic simulations analyses have revealed that hesperidin (HES) and rosuvastatin (ROS) have the best targeting potential for Mpro protein out of 10 phytochemicals and 6 statin compounds. The selected compounds were elaborated alone or with FAV into six nanoformulations FAV, ROS, HES, FAV/ROS, FAV/HES, and FAV/ROS/HES-loaded liposomes. Light and electron microscope evaluations confirmed the vesicular shape of all liposomal dispersions. The entrapment capacity and release extent from FAV/ROS/HES-loaded liposomes was the lowest compared to other nanoformulations. In vitro, the FAV/HES or FAV/ROS-loaded liposomes displayed the highest capacity to impede the replication of SARS-CoV-2 with IC50 of 0.738 and 3.28 μg/mL, respectively. These results confirmed the potential of hesperidin and rosuvastatin as adjuvant medications with Favipiravir to combat COVID-19 and suggest the preference of the combinatory treatments. Finally, our findings provide a rational for further in-vivo studies to evaluate the potential activities of these drug combinations to mitigate the adverse events of favipiravir and to boost its SARS-CoV-2 clearance efficacy.

Evolving cobalt cycle and urban mines in the EU, 1988–2020

Urban mines are vital for resource security and resilience, but the intricacies of their recycling processes are often overlooked. This study uses dynamic Material Flow Analysis to delve into the EU's cobalt cycle from 1988 to 2020, focusing on urban cobalt mining potential. We observed a significant shift in EU cobalt consumption patterns, with the demand for electric vehicle batteries surpassing that for superalloys, thereby positioning batteries as the primary cobalt consumers. Moreover, batteries increasingly dominate the cobalt in-use stock. The recycling process experiences substantial losses, especially in collection and pretreatment stages, reaching up to 87 %. Our findings indicates that urban cobalt mines could account for 57–66 % of the EU's total cobalt consumption, amounting to 166–193 kt in a high scenario. These insights emphasize the changing dynamics of the EU cobalt cycle and the importance of efficient urban cobalt mine management.

A dynamic topology analysis method for multi-ship encounters based on multi time-space network trees

This paper innovatively proposes a novel approach of topological analysis in the dynamic time-space domain of ship encounters under the joint action of multi-space network structural elements, based on the GIS spatial information platform and spatial topology analysis theory. The proposed method based on the ship's navigational motion information, encounter dynamic mode, relative time-space position distribution, etc., the method divides and intersects the time-space domain of the ship's encounter dynamics, and establishes an encountering dynamic time-space network tree in which space and attribute elements are collaboratively associated during the navigation. From the perspective of network topology analysis, the high-precision analysis of the spatial coupling characteristics and time-space trends of potential encountered dangers during ships dynamic navigation is achieved. To verify the effectiveness of the method, real encounter scenarios of M/T SANCHI and M/V CF Crystal were used as analysis cases. The results showed that the proposed method can precisely extract spatial relationships and spatio-temporal coupling feature information of potential hazards encountered between ships, with an average error of about 2.54% and an overall error between 1.94% and 3.53%.Simultaneously, the method's time efficiency results are thoroughly studied and compared, and it is discovered that the proposed method has good stability.

Continuous estimation of respiratory system compliance and airway resistance during pressure-controlled ventilation without end-inspiration occlusion

BackgroundAssessing mechanical properties of the respiratory system (Cst) during mechanical ventilation necessitates an end-inspiration flow of zero, which requires an end-inspiratory occlusion maneuver. This lung model study aimed to observe the effect of airflow obstruction on the accuracy of respiratory mechanical properties during pressure-controlled ventilation (PCV) by analyzing dynamic signals.MethodsA Hamilton C3 ventilator was attached to a lung simulator that mimics lung mechanics in healthy, acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD) models. PCV and volume-controlled ventilation (VCV) were applied with tidal volume (VT) values of 5.0, 7.0, and 10.0 ml/kg. Performance characteristics and respiratory mechanics were assessed and were calibrated by virtual extrapolation using expiratory time constant (RCexp).ResultsDuring PCV ventilation, drive pressure (DP) was significantly increased in the ARDS model. Peak inspiratory flow (PIF) and peak expiratory flow (PEF) gradually declined with increasing severity of airflow obstruction, while DP, end-inspiration flow (EIF), and inspiratory cycling ratio (EIF/PIF%) increased. Similar estimated values of Crs and airway resistance (Raw) during PCV and VCV ventilation were obtained in healthy adult and mild obstructive models, and the calculated errors did not exceed 5%. An underestimation of Crs and an overestimation of Raw were observed in the severe obstruction model.ConclusionUsing the modified dynamic signal analysis approach, respiratory system properties (Crs and Raw) could be accurately estimated in patients with non-severe airflow obstruction in the PCV mode.