Passive Protection Research Articles

The passive safety system of a high-speed multiple-unit train

The designing of modern high-speed multiple-unit trains in Ukraine should be carried out accounting for passive safety systems (PSSs) which include energy absorption devices (EADs). In the cases of trains collisions with obstacles these systems must automatically work to increase the passenger transportation safety, to reduce the risk of injury and death of passengers and service personnel, to minimize rolling stock damage. On the base of European experience in power head passive protection, a three-dimensional geometric model of the domestic power head frontal part with energy absorption devices containing cellular elements was developed. The protective devices for the power head and energy absorption devices installed in inter-car connections were proposed using the experience of development of the EP20 locomotive energy absorption device and results of its prototype crash test. The scientific methodology was developed to evaluation the EAD parameters. Finite-element models for studying the plastic deformation of EAD designs at impact and discrete-mass mathematical models for studying the dynamic loading of reference multiple-unit train vehicles in emergency collisions were developed in accordance with the DSTU EN 15227 requirements. As a research result, the parameters of the EAD designs have been obtained and compliance of the developed passive safety system with regulatory requirements has been proven.

Effect of Sulfide and Chloride Ions on Pitting Corrosion of Type 316 Austenitic Stainless Steel in Groundwater Conditions Using Response Surface Methodology.

This study investigates the corrosion resistance of Type 316 stainless steel as a candidate material for radioactive waste disposal canisters. The viability of stainless steel is examined under groundwater conditions with variations in pH, bisulfide ions (HS-), and chloride ions (Cl-) concentrations. Utilizing response surface methodology, correlations between corrosion factors and two crucial response variables, passive film breakdown potential and protection potential, are established. Cyclic potentiodynamic polarization tests and advanced analytical techniques provide detailed insights into the material's behavior. This research goes beyond, deriving an equation through response surface methodology that elucidates the relationship between the factors and breakdown potential. HS- weakens the passive film and reduces the pitting corrosion resistance of the stainless steel. However, this study highlights the inhibitory effect of HS- on pitting corrosion when Cl- concentrations are below 0.001 M and at equivalent concentrations of HS-. Under these conditions, immediate re-passivation occurs from the destroyed passive film to metal sulfides such as FeS2, MoS2, and MoS3. As a result, no hysteresis loop occurs in the cyclic polarization curve in these conditions. This research contributes to the understanding of Type 316 stainless-steel corrosion behavior, offering implications for the disposal of radioactive waste in geological repositories.

Evolution Process of the Interfacial Chemical Reaction in Ni-Rich Layered Cathodes for All-Solid-State Batteries.

All-solid-state batteries (ASSBs) have attracted much attention in the fields of energy storage, electric vehicles, and portable electronic devices due to their safety and high energy density. Ni-rich layered ternary materials (LiNi1-y-zCoyMnzO2, 1 - y - z ≥ 0.7) are considered to be among the most promising candidates for cathode materials in ASSBs due to their unique advantages. Nevertheless, the interfacial chemical reaction between the ternary cathode (NCM) and solid-state electrolytes (SSEs) has become the main issue to limit the long-cycle stability of the cathode. Relative studies have shown that when NCM materials are in direct contact with sulfide-based SSEs, byproducts generated by the interfacial chemical reaction accumulate at the interface, resulting in increasing interfacial impedance. However, up to now, the formation mechanism of the NCM/SSE interfacial chemical reaction, as well as its properties and evolution process, still lacks detailed characterization. In this paper, batteries at different stages during the long-cycling process are characterized to reveal the dynamic evolution process of the chemical reaction from the cathode-electrolyte interface to the interior of the particle and to determine the chemical reaction effect on the irreversible degradation of the battery capacity. On this basis, a surface coating of LiNbO3 is adopted to establish a passivation protection layer at the cathode-electrolyte interface. The coated battery has been subjected to 2000 charge/discharge cycles at a rate of 1 C and achieved a capacity retention rate of up to 82%.

Optimal selection of false ceiling systems in healthcare buildings: a multidimensional hierarchical analysis for sustainability

ABSTRACT False ceilings are non-structural elements present in buildings of all types. They act as passive protection elements and give the rooms in which they are located significant technical capacities. For healthcare buildings, false ceiling systems require a higher level of qualification than in other buildings, with strict requirements for acoustic insulation, fireproof stability, resilience, and noise absorption. In addition, they require exhaustive analysis, design, and sizing processes to ensure a high degree of reliability. This fact complicates their optimal selection. In this study, a multidimensional comparative analysis was made of 14 false ceiling systems that predominate in Spain's healthcare infrastructure. An analytic hierarchy process (AHP) was applied according to five pre-defined variables (LCA, Unit price, Working time, Thermal conductivity, and Maintenance accessibility) based on the technical, environmental, economic, and temporal dimensions. Life cycle assessment was used to define and quantify the environmental variables’ characteristic impact parameters. The optimal solution was found to be the removable mineral fibre system, with a value of 0.82 AHP pt/m2. This system has good technical properties and facilitates maintenance and cleaning tasks. In contrast, the continuous cement board false ceiling system was found to be the least favourable, with a score of 0.18 AHP pt/m2. The knowledge gained from this study will favour optimal decision-making in sizing healthcare infrastructure by providing a detailed view of that infrastructure to those responsible for its engineering, thereby enhancing the socioeconomic and environmental benefits.

Is titania acting as a synergist in intumescent fire retardant coatings designed for improving reaction to fire of wood?

Intumescent coatings based on ammonium polyphosphate (APP), are widely applied as passive fire protection. For flammable materials like wood, a rapid char expansion is needed to limit fuel gas release to the combustion zone and minimize reaction to fire. It is generally accepted that titanium dioxide (TiO2) improves the fire performance of coatings and acts as a synergist. This study discusses the role of TiO2 in intumescent coatings by investigation of real-time measurement of char expansion during heating, rheology, thermal analysis, cone calorimetry, and chemical composition by X-ray diffraction and IR spectroscopy under different TiO2 loadings. Results show that TiO2 enhance the rate of char expansion despite increased complex viscosity of the molten coating matrix. Further, thermal decomposition and onset of intumescent reactions remained unchanged by increased TiO2 loading which results in a lower final char height. Altogether, TiO2 acts as an incombustible filler reducing char expansion and not fulfilling the definition of a synergist in intumescent coatings for improving reaction to fire of wooden products.

The Military and Civilian Applications of Geopolymers

In this article, various geopolymer applications in the context of both existing and potential future military applications are summarized. Geopolymers are a type of alkaline activated concrete binder with many advantageous properties over ordinary Portland cement based materials. Geopolymers are first compared to ordinary Portland cement based materials in regards to their mechanical properties, thermal properties, chemical resistance and CO2 emissions during manufacturing. History of geopolymer applications and research is also discussed. Then, various geopolymer applications are summarized, including their use as a passive fire protection, material for general construction, “ink”for 3D printing. These types of applications are also discussed in the context of existing and potential military applications of geopolymers, including their use by U.S. armed forces and U.S. military research. Superior geopolymer resistance to explosions is also presented.

Seismic experimental analysis of a full-scale steel building with passive fire protections

The paper describes the results of an experimental campaign on the seismic behaviour of a full-scale concentrically braced steel frame designed according the EC8 and equipped with different types of passive fire protection. In this respect, fire protection boards made of calcium silicate and mineral spray-based fire protections were applied to dissipative members, such as the bracings, and to non-dissipative elements, such as one column of the bracing system. Two solutions of calcium silicate fire protection boards were employed: (i) a standard solution and (b) an improved solution conceived for seismic applications. Moreover, the external bays of the specimen equipped with mineral spray-based fire protections were filled with two fire walls both of them made of concrete blocks without and with seismic detailing, respectively. In total 10 tests on 4 frames, that also include a first test of the bare frame, were performed, and for each test different seismicity levels were applied. The hybrid simulation technique was used to maintain the relevance and accuracy of a full-scale test and also to optimize the use of the available test facilities. In this respect, only the ground floor of the prototype structure was physically tested in the laboratory, whereas the remainder of structure was numerically simulated. The tests showed that the fire protections and the fire walls did not suffer major damage owing to cyclic loading. Indeed, the damage was not likely to significantly affect the fire performance. The outcomes of the experimental results of all the tests are thoroughly described in the paper.

Exploring the Implementation Path of Passive Heat-Protection Design Heritage in Lingnan Buildings

To achieve indoor thermal comfort via natural ventilation, traditional buildings in South China’s Lingnan region have evolved distinct features tailored to the hot and humid climate conditions, involving site planning, function layout, and construction techniques. This study delves into the influences of these features on aspects such as sun-shading, ventilation, and heat insulation. By analyzing over ten Lingnan buildings in both the traditional and modern forms, several representative standardized models have been developed. Through a hybrid approach of combining qualitative and quantitative methodologies, including simulations, quantifications, and comparisons, several passive heat-protection measures commonly employed in Lingnan buildings were examined and evaluated. The effectiveness of shading, ventilation, and heat insulation in both traditional and modern buildings was assessed, resulting in the compilation of design principles for passive heat protection in buildings located in similar climatic zones. Key findings include (1) Shading: traditional methods reduce sunlight by 54.55%, while modern buildings enhance shading by applying new materials; (2) ventilation: traditional design achieves an outdoor wind speed of 1.5 m/s, improving thermal comfort, while modern Lingnan buildings optimize these principles; (3) insulation: traditional techniques maintain indoor temperatures below 26.0 °C, and modern buildings introduce innovation solutions for improved thermal insulation. In summary, traditional Lingnan design effectively addresses the challenges of the hot and humid climate by employing passive strategies for thermal comfort. Modern Lingnan buildings, in turn, preserve these principles while introducing innovative approaches.

Cyclic Voltammetry for Accurate Icing Detection on Simulated Aircraft Surfaces.

Icing and ice accretion on aerodynamically critical surfaces of an aircraft increase drag, reduce lift, and raise stalling speed, which pose significant safety hazards to aircraft while in flight. Icephobic coatings have been intensively investigated by the Canadian and global aerospace industries for passive ice protection. Nevertheless, effective icephobic coatings suitable for aerospace applications are far from ideal. Ice protection of an aircraft still relies on active ice protection systems based on heating, mechanical expulsion, and deicing fluids, which are heavy-weight, power-intensive, and unfriendly to the environment. To address these challenges, rapid and accurate detection of icing is highly desirable to activate these ice protection systems only when needed. To this end, cyclic voltammetry was used for the first time to detect the initiation of icing on aircraft surfaces with or without icephobic coatings. In this study, a water droplet was sandwiched between a screen-printed electrode and a simulated aircraft surface. Cyclic voltammograms were then collected as the temperature was slowly decreased until the droplet froze to form ice. A sharp spike in faradaic current was recorded in the voltammograms during the phase transition, suggesting a switch in the mass transfer mechanism from diffusion to a surface-confined pathway. This electrochemical signal could then be used to precisely indicate the onset of icing. The developed sensing method shows potential in icing detection to manage active ice protections and ameliorate icing risks in the aerospace and aviation industries.

Magnetically controlled interface weaving of dual-layer heterogeneous coatings with active and passive anti-corrosion protection

Polydimethylsiloxane (PDMS) elastomer exhibiting remarkable corrosion resistance and fouling release properties. However, their performances are often compromised due to the weak interfacial adhesion with rigid substrates. Herein, we have developed an innovative dual-layer heterogeneous coating via magnetic-controlled interface weaving technology, achieving a seamless integration of PDMS with a rigid epoxy (EP) substrate. Magnetic nanoparticles (Fe3O4@MPDA-MBT) were strategically incorporated into the coating system, guided by a magnetic field to facilitate their interfacial migration. This controlled migration of nanoparticles resulted in the formation of interface layer between the EP primer and PDMS topcoat, leading to a sharp increase in PDMS adhesion strength (3.0 MPa), which is over 7 times greater than that of control counterpart (0.4 MPa). Additionally, Fe3O4@MPDA-MBT were selectively enriched adjacent to the metal substrate, thereby endowing the coating with outstanding corrosion resistance, due to the quick releasing of enough MBT inhibitors, as confirmed by electrochemical tests with high corrosion resistance value (2.2 × 108 Ω·cm2). Also, the topcoat PDMS enabled the dual-layer heterogeneous coating to achieve fouling-release and cavitation resistance.

An automated computation method for flexible protection systems based on neural networks

An automated computation method is proposed in this paper to address the problems of enormous computational difficulty and low efficiency in flexible protection systems. This method uses neural networks to demonstrate the complex nonlinear mapping relationships between the system’s specifications and performance. Use the finite element numerical simulation model validated by a full-scale impact test on the 750 kJ passive flexible protection system for massive parametric analysis, and extract the critical computation results as the label space. Conducted mechanical tests on critical components, analyzed the mechanical characteristics of each component, and extracted training features to form a sample space. The label space and sample space formed a dataset containing 1828 sets of data and used 1700 sets of data to train a neural network while using the remaining 128 sets of data to test. The maximum predicted error was 8.33 %, and the maximum average error was 3.73 % from the test. The proposed method can complete the computation in just 6 s, with a computation speed of 520 times that of the fastest finite element method, significantly improving the computation efficiency of the flexible protection system and reducing the computational difficulty.

Preparation and immunoprotective effects of a virus-like particle candidate vaccine of the dominant epidemic D3 genotype coxsackievirus A6 in China

Coxsackievirus A6 of the D3a genotype (CVA6 D3a) is a primary pathogen causingmainland of China's hand, foot, and mouth disease (HFMD). Viral-like particle (VLP) vaccines represent a potential candidate vaccine to prevent HFMD. This study collected Anti-CVA6 D3a VLPs serum from BALB/c female mice immunized using CVA6 D3a VLPs. The neutralizing antibody levels were compared against the representative 14-JX2018 (D3a) and N4-YN2015 (D3b) strains between the antisera of different immune pathways. The immunoprotective effect of anti-CVA6 D3a VLPs against these strains was monitored using pathological sections and immunohistochemical results of lung and skeletal muscle tissues in seven-day-old Institute of Cancer Research (ICR) mice. Immunological protection against different branches of viruses was evaluated in 7-day-old (serum passive immune protection) and 14-day-old (VLPs active immune protection) neonatal ICR mice models. Serum-neutralizing antibody levels were positively correlated with the number of immunizations and higher against 14-JX2018 than against N4-YN2015. Furthermore, these levels were significantly higher with abdominal injection than intramuscular injection. The immunized serum of 7-day-old ICR mice inoculated three times was 100 % protected against CVA6 D3a 14-JX2018 (lethal titer: 106.25 TCID50) and CVA6 D3b N4-YN2015 (lethal titer: 105.25TCID50) fatal attacks, respectively. For ICR mice that have completed two active immunizations for 14 days, both CVA6 D3a 14-JX2015 (challenge titer: 108.25 TCID50) and CVA6 D3b N4-YN2015 (challenge titer: 107.25 TCID50) were used for the challenge, and the mice were able to survive. Overall, the CVA6 D3a VLPs prepared in this study are a potential vaccine candidate for CVA6, as it has the optimal protective effect against both CVA6 D3a and D3b evolutionary branches viruses.

Nanocontainers with synergetic inhibition and corrosion protection abilities towards intelligent self-healing coatings

A new network structure of Ce (III) modified I-Ti3C2Tx (IT) (Ce@IT) was generated by covalent and/or coordination networks with a metal cation center of Ce (III) and imidazolium on the IT surface as a linker. The lamellar Ce@IT nanocomposites were formed with chemically bonded Ce-N bonds, which increased the crosslink density, ductility, and toughness of epoxy coatings, particularly by improving toughness and elongation at break. Furthermore, Ce3+ could be released from Ce@IT nanocomposites to form insoluble cerium-based oxide/hydroxide deposited on the substrate surface in the scratch areas and offer outstanding active and passive protection to epoxy coatings.

History of Environmental and Climatic Changes Recorded in Lacustrine Sediments—A Wigry Lake Case Study

Wigry Lake represents one of the most beautiful and valuable postglacial lakes that is located in the north-eastern part of Poland. It has been an object of scientific interest for over a century, but the most intense period of research started in 1997 and resulted in the production of numerous papers of a multidisciplinary range. The lake is especially well analyzed in terms of its sediments, which were studied using geophysical methods and using traditional lake cartography based on the sampling of sediments and their geochemical characterization. Nearly two decades of research has resulted in the extraction of over 1200 sediment samples, which facilitated the analysis and the description of five main sediment types that can be found at the bottom of Wigry Lake, i.e., carbonate gyttja, lacustrine chalk, clastic sediment, fluvial-lacustrine sediment, and organic gyttja. A very thorough vertical as well as spatial examination of Wigry Lake sediments, together with paleobiological research and isotopic dating, allowed researchers to analyze the history of environmental changes in the lake and its immediate vicinity, including anthropogenic changes. Wigry Lake had been preserved as a pristine lake for a long time, and, despite the significant growth of anthropopressure, which began in the 17th century and intensified in the 20th century, it retained its natural character to a large extent. This was possible mainly due to the favorable morphometry of the lake (large depth and capacity of the reservoir) and different forms of active and passive protection, introduced mainly after the establishment of the Wigry National Park in 1989.

Next-generation of smart dressings: Integrating multiplexed sensors and theranostic functions

Non-healing wounds represent a significant burden for healthcare systems and society, giving rise to severe economic and human issues. Currently, the use of dressings and visual assessment represent the primary and standard care for wounds. Conventional dressings, like cotton gauze, provide only passive physical protection. Besides, they end up paradoxically hampering the wound-healing process by producing tissue damage and pain when removed during routine check-ups. In response to these limitations, researchers, engineers, and technologists are developing innovative dressings that incorporate advanced diagnostic and therapeutic functionalities, coined as “smart dressings”. Now, the maturation of smart dressing is bringing them closer to real-life applications, leading to an exciting new generation of these devices. The next generation of smart dressings is capable of monitoring in real-time multiple biomarkers while including pro-healing capabilities in a single platform. Such multiplexed and theranostic smart dressings are expected to offer a timely biomarker-directed diagnosis of non-healing wounds while enabling rapid, automated, and personalized treatments of infection and chronicity. Herein, we provide an insightful overview of these advantageous devices, delving into the diverse spectrum of possible engineering strategies. This encompasses the use of electrochemical and optical platforms with diverse multiplexing architectures, such as multi-zone sensing arrays and multi-layered devices. Open or closed-loop theranostic mechanisms using various stimuli-responsive materials that could be internally or externally controlled are also included. Finally, a critical discussion on the main challenges and future directions of smart dressings is also offered.

Superhydrophobic Coating Solutions for Deicing Control in Aircraft

The risk of accidents caused by ice adhesion on critical aircraft surfaces is a significant concern. To combat this, active ice protection systems (AIPS) are installed on aircraft, which, while effective, also increase fuel consumption and add complexity to the aircraft systems. Replacing AIPS with Passive Ice Protection Systems (PIPS) or reducing the energy consumption of AIPS could significantly decrease aircraft fuel consumption. Superhydrophobic (SH) coatings have been developed to reduce water adherence to surfaces and have the potential to reduce ice adhesion, commonly referred to as icephobic coatings. The question remains whether such coatings could reduce the cost associated with AIPS and provide durability and performance through suitable tests. In this paper, we then review current knowledge of superhydrophobic and icephobic coatings as potential passive solutions to be utilized alternatively in combination with active systems. We can identify physical parameters, coating composition, structure, roughness, and morphology, durability as properties not to be neglected in the design and development of reliable protection systems in aircraft maintenance.

Numerical study on the maximum temperature rise and thermal-smoke front spread length in the upstream of semi-transverse ventilated Underground Traffic Link Tunnels

To fill the gap between the high realistic demand and lack of research basis, the process of smoke spread in Underground Traffic Link Tunnel fires during operation is investigated by numerical modeling. Good agreement between numerical predictions and experimental measurements for the longitudinal temperature has been achieved. Good agreement between numerical predictions and experimental measurements for the longitudinal temperature has been achieved. The characteristics of smoke transportation at key locations (e.g., maximum excess temperature and smoke fronts) were analyzed. A novel division method for the maximum lengths of smoke bays, which depends on thermal-smoke front spread length established from the characteristic number Ri = Q̇fuel∗1/3/V∗ of mixed convection, to utilize the nature of smoke as much as possible during a fire is provided based on dimensional analysis and similarity principle. The margin of error between the final model prediction in this paper and the simulation was within plus or minus 10%. The outcomes of this study are believed to have practical guidance significance for linkage and interlock control of smoke management and passive fire protection design in tunnels during operation with a transverse ventilation system.

Building fire safety management analysis based on the reliability assessment method of making safety systems in greenhouse display buildings

Fires must be alerted and anticipated or detected as early as possible. If a fire occurs, it will be fatal such as damage to buildings, infrastructure, other facilities and can even result in casualties. Therefore, a reliable fire protection system must be applied. To prevent or anticipate fires, detection must be carried out as early as possible and prepared facilities or infrastructure for fire safety. The Green House display building is an exhibition building of living plants from various mountains in Indonesia including the mountains of Java, the mountains of Sumatra, the mountains of Kalimantan, and the mountains of Papua. This building is the only building in Indonesia, which presents the atmosphere of the mountains exactly the same as the original mountains, both plants, soil and air temperature, but is in a closed room. Plants and soil are taken directly from the associated location. This building is allegedly very prone to fire because there are so many flammable materials such as leaves, wood and others. As well as forests in Indonesia, especially in Kalimantan and Sumatra where fires often occur. Therefore, the application of Building Fire Safety Management in this building must be applied as well as possible. Fire safety management in question includes: completeness of facilities and infrastructure, active protection systems and passive protection systems. Active protection systems such as fire detection devices for this building cannot use ordinary systems, because in this building, the atmosphere is like mountains with many big trees. To ensure that the building can be declared reliable in terms of building safety, especially fire safety, it is necessary to check the reliability of the building. The inspection can be carried out by several methods, including analyzing based on applicable standards and analyzing based on the assessment of the reliability of the building safety system referring to the Settlement Research and Development Center, Research and Development Agency PU, Department of Public Works in 2005 (Pd-T-11-2005-C).

Performance Research of Natural Mica Modified with Zirconium-Based Metal-Organic Frameworks for an Epoxy Resin Anti-Corrosion Coating.

A new composite material made from mica and a metal-organic framework (MOF) has been developed to improve the anticorrosive capabilities of epoxy resin coatings. The layered mica was loaded with denser and more uniform UIO-66 nanoparticles after modifying the composite with polyethyleneimine (PEI). The composites were used as fillers to prepare epoxy coatings that exhibited long-lasting active (labyrinth effect produced by mica) and passive (pH-sensitive release of corrosion inhibitors) corrosion protection. Settling experiments showed that polyethyleneimine improved the composites' compatibility in epoxy resin. After being immersed in a 3.5 wt.% NaCl solution for 60 days, the adhesion of PMC-UIO@MBT/EP increases to 9.01 MPa, while the water absorption rate only reaches 2.57%. It indicates that the coating has good barrier properties and stability. After being soaked in a 3.5 wt.% NaCl solution for 60 days at pH = 7, PMC-UIO@MBT/EP exhibits high low-frequency impedance (8.30 × 108 Ω), as demonstrated by the electronic impedance spectrum (EIS). In addition, the coating also exhibited the highest low-frequency impedance after 30 days in 3.5 wt.% NaCl solution at pH = 11.

A passive fire protection method for main cables and slings of suspension bridges utilizing fiber felt/aerogel composites

The paper proposes a fire protection method for the main cables and slings (cables for short) of suspension bridges based on fiber felt/aerogel composites. Glass fiber felt/aerogel composite (GFAC), basalt fiber felt/aerogel composite (BFAC), and high silica fiber felt/aerogel composite (HSFAC) were prepared using silica aerogel as filler. Heat-shielding tests and thermal stability analysis were conducted on these three thermal insulation composites. A fire test platform was established to study temperature distribution and fire protection range of suspension bridge cables. The following results were obtained: (1) Within 6000 s, the 5 mm-thick HSFAC can resist 700 °C butane fire, while 7 mm-thick HSFAC blocks 1000 °C flame. The 10 mm-thick HSFAC provides better thermal insulation. (2) Two fire protection zones are identified according to temperature ranges of 1000 °C to 700 °C and 700 °C to 300 °C, respectively, with minimum heights of 12.8 m and 20.8 m. (3) For a 90-minute fire protection, the main cables in the former zone are wrapped with 10 mm-thick HSFAC, while the slings are chosen to be 7 mm-thick HSFAC. In the latter zone, main cables and slings are covered with 5 mm-thick HSFAC. The fire protection method has been implemented on a suspension bridge in Guangzhou, China.