Suppression System Research Articles

Recent Advances in Mycotoxin Detection: A Review

Mycotoxins, toxic compounds produced by fungi like Aspergillus and Penicillium, pose significant health risks even at low concentrations. Detecting these contaminants in food requires intricate methods due to their low levels and complex sample matrices. Historically, toxic fungi research began with mushrooms but expanded in the mid-1800s to include other fungi, such as Claviceps purpurea, which caused ergotism through contaminated rye. Mycotoxins severely impact both human and animal health, causing issues like cancer, immune suppression, and nervous system damage, while also disrupting global food trade, affecting around 25% of crops worldwide. Traditional detection methods include chromatography (TLC, LC, GC, HPLC) and immunological assays like ELISA and LFI, though these methods have limitations. Recent advances in mycotoxin detection feature innovations like biosensors, fluorescence-based techniques, phage display technology, and smartphone-enabled systems, which offer enhanced sensitivity, specificity, and rapid detection capabilities. These methods represent a promising shift towards more efficient and precise mycotoxin analysis in food safety.

Active micro-vibration isolation system for adaptive vibration suppression tests using piezoelectric stack actuator

An active micro-vibration isolation system for adaptive vibration suppression using piezoelectric stack actuators is presented, along with the discrete time modelling method, real-time adaptive controller design, and hardware implementation. The system comprises piezoelectric stack actuators, capacitive displacement sensors, power amplifiers, signal conditioners, and a real-time computer. A discrete asymmetric Bouc-Wen model is developed to characterize the nonlinear behavior of the piezoelectric stack actuators. System identification is conducted using an improved particle swarm optimization method, specifically the Hybrid PSO-Jaya algorithm, which sequentially integrates the PSO algorithm with the Jaya algorithm. Additionally, an improved adaptive filtering algorithm employing affine projection, referred to as the FXAPA algorithm, is introduced to facilitate real-time control. The efficacy of the proposed active micro-vibration isolation technology is validated through micro-vibration suppression tests.

Case study on thermal and flow analysis of a water mist on a pool fire in a ventilated engine compartment

Public transport buses and other large vehicles are facing increasing engine fire issues stemming from higher operating temperatures, phonic insulation and low maintenance time. The fire suppression systems currently employed or considered for vehicles could be used for the protection of buses. Water mist is one of these technologies. One of the challenges a water mist faces for the fire protection of small enclosures is the ventilation. Inside a full scale engine compartment of a truck, the interaction and heat transfer between a n-heptane pool fire and water mist droplets are studied using velocimetry techniques. Most notably, the influence of the nozzle operating pressure and a variable cross-flow ventilation on the extinguishing performance is explored. In this preliminary study without clutter, the results show the importance of the ventilation flow on the performance of the water mist. Moderate ventilation speeds up to 3.2ms-1 show an improvement of the extinguishing time over natural ventilation while a higher ventilation speed of 6.4ms-1 degrades the extinguishing performance of the mist. For low-pressure water mists, the momentum of the spray is the most important factor for water mist extinguishing performance.

Study on flame retardant and smoke suppression of EPDM by sepiolite expansion flame retardant system

AbstractA large amount of smoke will be produced during the combustion of ethylene propylene diene monomer(EPDM), which seriously endangers the environment and personal safety. In this study, K‐SEP was obtained by modifying sepiolite with KH550, and two bio‐based flame retardant and smoke suppression systems AEGS and PEGS were prepared by combining ammonium polyphosphate intumescent flame retardant system (AEG) and piperazine pyrophosphate intumescent flame retardant system (PEG), respectively. The flame retardant and smoke suppression properties of AEGS and PEGS on EPDM matrix composites were investigated. The experimental results show that the LOI values of EPDM/AEGS3 and EPDM/PEGS3 composites with 3 phr K‐SEP are 8.1% and 5.5% higher than those of the blank samples without sepiolite. TSP decreased by 26.3% and 14.3% respectively, which proved that sepiolite has important research value in the field of flame retardant and smoke suppression of polymer materials.

Making waves: The progress of management strategies for cleaning and rinsing of PFAS-impacted fire suppression systems

Aircraft rescue firefighting (ARFF) vehicles often contain residual levels of per- and polyfluoroalkyl substances (PFAS) due to the global use of legacy and current use of aqueous film-forming foam (AFFF) for class B firefighting. However, numerous countries are transitioning to fluorine-free foam (F3) alternatives. There is, thus, an urgent need to develop efficient methods to rinse and clean interior ARFF surfaces thereby avoiding expensive replacement costs and preventing further discharge of PFAS to the environment. However, the unique self-assembly behavior of amphiphilic PFAS is a complicating factor that can result in measurable levels of PFAS within replacement F3 following cleanout efforts (i.e., the rebound effect). This Making Waves article aims to elucidate the emerging challenges associated with cleanout of impacted ARFF vehicles and introduce the current efforts for PFAS management of rinsate derived from cleanout of impacted fire suppression infrastructure.

Research on the mechanism and extinguishing technology of substation fire

This article utilizes the combustion characteristics of combustible materials to investigate the fire mechanisms and extinguishing technologies in substations. Experimental and simulation analyses have revealed patterns in heat release rates, flame heights, flame temperatures, flame resistance, and particulate ash. A modular solution employing a novel hot aerosol fire suppression system has been introduced. This system integrates independently manufactured alarm devices, initiation devices, sensors, and fire suppression equipment, offering either semi-automatic or fully automatic functionality. It serves both targeted fire suppression and complete immersion scenarios. By developing an integrated fire suppression and database alert system, enhanced intelligent fire protection has been attained, thereby advancing the sophistication of substation fire safety and the digitization of power networks.

Evolving Escherichia coli to use a tRNA with a non-canonical fold as an adaptor of the genetic code.

All known bacterial tRNAs adopt the canonical cloverleaf 2D and L-shaped 3D structures. We aimed to explore whether alternative tRNA structures could be introduced in bacterial translation. To this end, we crafted a vitamin-based genetic system to evolve Escherichia coli toward activity of structurally non-canonical tRNAs. The system reliably couples (escape frequency<10-12) growth with the activities of a novel orthogonal histidine suppressor tRNA (HisTUAC) and of the cognate ARS (HisS) via suppression of a GTA valine codon in the mRNA of an enzyme in thiamine biosynthesis (ThiN). Suppression results in the introduction of an essential histidine and thereby confers thiamine prototrophy. We then replaced HisTUAC in the system with non-canonical suppressor tRNAs and selected for growth. A strain evolved to utilize mini HisT, a tRNA lacking the D-arm, and we identified the responsible mutation in an RNase gene (pnp) involved in tRNA degradation. This indicated that HisS, the ribosome, and EF-Tu accept mini HisT ab initio, which we confirmed genetically and through in vitro translation experiments. Our results reveal a previously unknown flexibility of the bacterial translation machinery for the accepted fold of the adaptor of the genetic code and demonstrate the power of the vitamin-based suppression system.

Performances of the ITER Pressure Suppression System during unstable steam condensation regimes

Abstract The paper deals with the qualification of the main safety system of the nuclear fusion reactor ITER: the Vacuum Vessel Pressure Suppression System (VVPSS). This safety system manages the Loss of Coolant Accident (LOCA), that could occur in the Vacuum Vessel (VV), avoiding a significant increase of the internal pressure that could breach the primary confinement barrier. Steam condensation occurs at sub-atmospheric pressure. This condition is original respect the usual applications of steam direct condensation in nuclear fission reactors. An extensive experimental research program, funded by ITER Organization, on reduced scale experimental rigs (scale 1/22 and 1/10) have been carried out at the University of Pisa. Unstable condensation regimes occurred during some tests at about 500 g/s of steam mass flow rate (10 % of the maximum steam mass flow rate foreseen for the relevant accidental scenarios). In these conditions, high intensity vibrations of the whole experimental rig occurred. These events can be classified as ‘Chugging’ or Condensation Induced Water Hammer (CIWH). &amp;#xD;The performed tests have been analysed elaborating the images of the video-cameras located in the pool and comparing the steam jet shape with the acceleration values recorded by an accelerometer mounted on the sparger structure.&amp;#xD;These elaborations permitted to evaluate the dynamic of bubble collapse, the volume of the developed external bubbles, the collapse frequency as function of thermal-hydraulic parameters. &amp;#xD;Moreover, the paper emphasizes the beneficial effects of non-condensable gases on the unstable condensation regimes. In fact, the non-condensable gas inhibits the occurrences of Water Hammer inside the sparger and eliminates the thermal stratification inside the water pool increasing the turbulence.&amp;#xD;

Population suppression by release of insects carrying a dominant sterile homing gene drive targeting doublesex in Drosophila

CRISPR homing gene drives can suppress pest populations by targeting female fertility genes, converting wild-type alleles into drive alleles in the germline of drive heterozygotes. fsRIDL (female-specific Release of Insects carrying a Dominant Lethal) is a self-limiting population suppression strategy involving continual release of transgenic males carrying female lethal alleles. Here, we propose an improved pest suppression system called “Release of Insects carrying a Dominant-sterile Drive” (RIDD), combining performance characteristics of homing drive and fsRIDL. We construct a split RIDD system in Drosophila melanogaster by creating a 3-gRNA drive disrupting the doublesex female exon. Drive alleles bias their inheritance in males, while drive alleles and resistance alleles formed by end-joining cause dominant female sterility. Weekly releases of RIDD males progressively suppressed and eventually eliminated cage populations. Modeling shows that RIDD is substantially stronger than SIT and fsRIDL. RIDD is also self-limiting, potentially allowing targeted population suppression.

High-dimensional nonlinear flutter suppression of variable thickness porous sandwich conical shells based on nonlinear energy sink

Nonlinear energy sink (NES) is widely applied in engineering field due to the advantages of light weight, high robustness, unidirectional energy transfer, rapid and broadband vibration isolation. In this paper, nonlinear energy sink is utilized to suppress vibration of the variable thickness porous sandwich conical shells for the first time, and the high-dimensional nonlinear flutter suppression characteristics of the system of simply supported variable stiffness truncated porous sandwich conical shell coupled NES under aerodynamic force and thermal stress are investigated. By applying the first-order shear deformation theory (FSDT), Hamilton's principle and Galerkin technique, the high-dimensional nonlinear ordinary differential flutter suppression equations of the system appended with NES are established. The accuracy of the theoretical approach is ensured by the comparison of frequency results, while the NES dissipated kinetic energy ratio and the comparison of NES performance with other suppression systems are presented to prove the effectiveness of NES on nonlinear flutter suppression. The time history diagrams and limit cycle oscillation (LCO) amplitude curves, which reflect the high-dimensional nonlinear flutter suppression effect of NES, are obtained by employing the Runge-Kutta method. The effects of aerodynamic pressure, the parameters and positions of single NES, and the positions of parallel NES and series NES on the high-dimensional nonlinear flutter suppression characteristics of the system attached with NES are discussed in depth. Finally, the optimal high-dimensional nonlinear flutter suppression scheme is arrived.

Lightweight deep neural network for radio frequency interference detection and segmentation in synthetic aperture radar

Radio frequency interference (RFI) poses challenges in the analysis of synthetic aperture radar (SAR) images. Existing RFI suppression systems rely on prior knowledge of the presence of RFI. This paper proposes a lightweight neural network-based algorithm for detecting and segmenting RFI (LDNet) in the time-frequency domain. The network accurately delineates RFI pixel regions in time-frequency spectrograms. To mitigate the impact on the operational speed of the entire RFI suppression system, lightweight modules and pruning operations are introduced. Compared to threshold-based RFI detection algorithms, deep learning-based segmentation networks, and AC-UNet specifically designed for RFI detection, LDNet achieves improvements in mean intersection over union (MIoU) by 24.56%, 13.29%, and 7.54%, respectively.Furthermore, LDNet reduces model size by 99.03% and inference latency by 24.53% compared to AC-UNet.

Feasibility of the Compton Suppressed Gamma-ray spectrometry for proton therapy applications

The presence of the Bragg peak and its use in proton therapy cause less damage to healthy tissues. For optimal use of the proton beam in proton therapy, it is necessary to monitor the deviation of its range during treatment. The prompt gamma rays originated from the nuclear reactions of the proton beam with tissue elements can be applied for this purpose. The spatial distribution of prompt gamma rays can be used to estimate the range of the incident charged particles. Detecting a wide energy range of gamma rays, up to 10 MeV, is the most challenging step of the proton dose verification by using prompt gamma spectroscopy. Compton suppression is a system that is used to reduce the contribution of scattered gamma rays. This technique will cause better detection of the peaks of low-energy prompt gamma rays. In this research, the performance of a Compton suppression system has been investigated in two fields for proton therapy and for elemental analysis of materials using isotopes by a wide range of gamma energies. At first, by using the simulated Compton suppression system, the calculations of the prompt gamma ray spectra emitted from the brain phantom during the radiation of 150 MeV protons were presented. The results indicated that the low energy elements peaks such as 40Ca (1.37 MeV) with CSF equal to 1.138 appeared in the suppressed spectrum. Also, it was possible to detect 14N (2.31 MeV) and 16O (6.13 MeV) peaks equivalent to the CSF 2.449 and 2.067 respectively. In the next step, it was possible to detect the low energy peaks of 152Eu and 155Eu isotopes in the suppressed spectrum. For this purpose, the minimum relative intensity required to detect all 152Eu and 155Eu peaks was equivalent to 0.001 and 0.002 respectively. CSF for the lowest energies such as 105 keV and 344 keV was equal to 1.169 and 1.184. The simulation was done using the GEANT4 Monte-Carlo toolkit.

Meeting the challenge of mitigating Li-ion battery fires for aviation

The aviation industry faces a pressing challenge in reducing its environmental footprint, especially with the projected growth in global passenger traffic. Electrification and more-electric aircraft, particularly through Lithium-ion Battery (LiB) systems, offers a promising pathway to reduce emissions but introduces significant safety concerns, particularly regarding thermal runaway (TR) events. This prospective paper examines the unique challenges posed by aviation environments for developing safe LiB systems. It discusses multifaceted mitigation approaches, integrating fire containment structures with advanced thermal management and fire protection technologies. Various cooling technologies and fire suppression agents are explored for their effectiveness in extinguishing LiB fires and mitigating thermal runaway propagation. Integrated LiB suppression systems are proposed to combine fire containment, suppression, and thermal management functionalities for achieving the demanding specific energy density levels that will be required. Scaling safe LiB pack solutions for commercial aviation requires coordinated efforts among regulators, original equipment manufacturers (OEMs), engineers, and researchers to establish standardized design criteria, develop validated modeling tools, and establish rigorous certification testing requirements. In conclusion, addressing the safety concerns of large LiB packs in aircraft applications requires a holistic, integrated approach. This paper provides insights into current research, identifies key challenges, and outlines future directions for advancing LiB safety in aviation.

Harmonic resonance evaluation and suppression of railway power conditioner-network-train coupling system

The coupling of railway power conditioner (RPC), network, and train will change the impedance characteristics of the existing traction power supply systems, which will lead to the unclear law of high-frequency harmonic resonance. This paper aims to study the resonance mechanism of the RPC-network train coupling system, and then solve the resonance problem of the existing traction power supply system from the perspective of reshaping the high-frequency impedance of the system. Firstly, the RPC-network-train coupling system’s dynamic node admittance matrix is established. After that, a comprehensive resonance evaluation method is proposed to obtain the resonance impact factors (RIFs) of multiple virtual impedances in the control strategy and the filtering parameters, which can realize the comparison and selection of five existing impedance reshaping strategies. To ensure the safe and stable operation of the RPC-network-train coupling system, a multi-objective sorting optimization strategy (MOSOS) considering resonance suppression, harmonics filtering, filter cost, and control system stability is proposed for the RPC based on the RIFs. Finally, the effectiveness of the proposed method is verified by the simulation result in MATLAB/Simulink and the experiment result in the StarSim hardware-in-the-loop (HIL) platform respectively.

Enhancing Flame Retardancy and Smoke Suppression in EPDM Rubber Using Sepiolite-Based Systems.

The burning of Ethylene-Propylene-Diene Monomer (EPDM) rubber generates substantial smoke, posing a severe threat to the environment and personal safety. Considering the growing emphasis on safety and environmental protection, conventional non-smoke-suppressing flame retardants no longer satisfy the present application requirements. Consequently, there is an urgent need to develop a novel flame retardant capable of suppressing smoke formation while providing flame retardancy. Sepiolite (SEP), a porous silicate clay mineral abundant in silica and magnesium, exhibits notable advantages in the realm of flame retardancy and smoke suppression. This research focuses on the synthesis of two highly efficient flame-retardant smoke suppression systems, namely AEGS and PEGS, using Enteromorpha (EN), graphene (GE), sepiolite (SEP), ammonium polyphosphate (APP), and/or piperazine pyrophosphate (PPAP). The studied flame-retardant systems were then applied to EPDM rubber and the flame-retardant and smoke suppression abilities of EPDM/AEGS and EPDM/PEGS composites were compared. The findings indicate that the porous structure of sepiolite plays a significant role in reducing smoke emissions for EPDM composites during combustion.

Infrared radiation characteristics simulation of exhaust suppression type ships

An equivalent calculation method for the infrared-suppressed ship’s infrared radiation is carried out, which couples thermal characteristics of the ship surface and the exhaust system. Firstly, a refined physical model for the infrared suppressed exhaust system is proposed, which considers the processes of convective heat transfer and radiative heat transfer. The model generates the equivalent heat flow boundary conditions of the internal heat source through the numerical calculation of Computational Fluid Dynamics (CFD), and combines with the energy balance physical model. The energy balance model on the ship surface is developed, which considers external thermal environment conditions including itself radiation, solar radiation, atmospheric radiation, and reflective radiation among surface elements. The temperature calculation model for the ship with a jet exhaust system is formed. Subsequently, an exhaust-suppressed ship infrared radiation calculation model is formed based on the infrared radiation rendering of solid targets and the narrow spectral principle of exhaust plumes, which considers the spontaneous radiation and environmental radiation of ships. Finally, the infrared simulation results are compared and verified based on experimental data. The results indicate that the infrared radiation error on the ship’s typical parts is less than 30 %. Additionally, 90.1 % of the cabin walls using exhaust suppression systems have a temperature difference of less than 3 K under different operating conditions. It suggests that the exhaust suppression system is effective in reducing the temperature of the cabin wall. The calculation method for ship infrared characteristics constructed in this paper has reasonable results, and it can be used for infrared characteristic analysis of exhaust suppression ships.

Evaluation of Fire Protection System in Library Building Universitas Negeri Padang

The fire of a building will have a major impact on the building owner, both in the form of material, moral and environmental losses. In residential areas, offices and other public facilities often cause casualties. Therefore, a building needs to take into account the risk of fire so that building users can carry out activities safely and comfortably. One of the causes of fires is the fire suppression system that has not received full attention, where there is often an inadequate building fire protection system. The UNP Library Building is one of the public facilities buildings that are always crowded with students. It is necessary to evaluate the availability of the fire protection system to ensure the safety and comfort of its users. This research is in the form of an evaluation of the availability and completeness of the available fire protection systems and their remedies against the threat of fire. The data was taken through direct observation and question and answer and the distribution of questionnaires with the library. From the results of the analysis of the fire protection system inspection of the UNP Library building, it is known that on the 1st floor the lowest rediness value is 18.9%, for the 2nd and 3rd floors is 44.1%, the 4th and 5th floors are 45.9% and 45.6 % fulfilled the requirements based on the Minister of Public Works Regulation No. 26/PRT/M/2008.

Stair‐Stepping Mechanical Metamaterials with Programmable Load Plateaus

AbstractMaterials with target load plateaus offer the potential for developing innovative vibration suppression and isolation systems for applications such as satellite platforms, submarines, and electric vehicles. However, implementing these materials can pose significant challenges. In this study, stair‐stepping mechanical metamaterials with programmable load plateaus are presented, which are created via a three‐level (unit, module, and 3D object) construction strategy. The strategy inspired by the inverse design concept achieves tunability in the number and properties of load plateaus within the force–displacement profiles of the metamaterials. This approach even yields appealing stair‐stepping response patterns, as validated by experiments and finite element simulations. Promisingly, programming the unit from its initial configuration to a “zero stiffness” configuration enables these metamaterials excellent vibration isolation performance. Furthermore, two reversible methods are proposed for switching among various unit configurations, namely shape memory programming and supporting payload. This innovative design strategy for programmable load plateaus opens up new possibilities for creating metamaterials with customized force–displacement responses. It also provides opportunities to incorporate multimodal vibration isolation capabilities into precision devices.

СРЕДСТВА ПОЛУЧЕНИЯ И ПЕРСПЕКТИВЫ ПРИМЕНЕНИЯ КОМПРЕССИОННОЙ ПЕНЫ В ПОЖАРОТУШЕНИИ

The subject of the article is modern fire extinguishing technologies based on compression foam. The purpose of the study is to study the means of obtaining and the prospects for using compression foam in fire fighting. Methods: analysis and synthesis, modeling. The results obtained indicate that compression foam has a number of advantages compared to water and conventional air-aspirated foam, so it can be used to extinguish fires in many industries and areas. A diagram of the production of compression foam is presented (the foam concentrate acts as a foaming agent) and a diagram of an autonomous installation for the production of compression foam. It is noted that one of the significant advantages of CAFS is the ability to create a finished product that matches a specific type of fuel or a specific situation. The characteristics of the SmartCAFS product have been defined. A typology of the use of compression foam depending on the type of incident is presented. The results of fire resistance tests of various foams are presented. It is concluded that fire suppression systems using compression foam have significant advantages, such as minimizing the spread of fire, the volume of water required to cover large areas, costs and placement, and the integration of CAFS with digital technologies.

Bioproduction Platform to Generate Functionalized Disulfide-Constrained Peptide Analogues.

Disulfide-constrained peptides (DCPs) have gained increased attention as a drug modality due to their exceptional stability and combined advantages of large biologics and small molecules. Chemical synthesis, although widely used to produce DCPs, is associated with high cost, both economically and environmentally. To reduce the dependence on solid phase peptide synthesis and the negative environmental footprint associated with it, we present a highly versatile, low-cost, and environmentally friendly bioproduction platform to generate DCPs and their conjugates as well as chemically modified or isotope-labeled DCPs. Using the DCP against the E3 ubiquitin ligase Zinc and Ring Finger 3, MK1-3.6.10, as a model peptide, we have demonstrated the use of bacterial expression, combined with Ser ligation or transglutaminase-mediated XTEN ligation, to produce multivalent MK1-3.6.10 and MK1-3.6.10 with N-terminal functional groups. We have also developed a bioproduction method for the site-specific incorporation of unnatural amino acids into recombinant DCPs by the amber codon suppression system. Lastly, we produced 15N/13C-labeled MK1-3.6.10 with high yield and assessed the performance of a semiautomated resonance assignment workflow that could be used to accelerate binding studies and structural characterization of DCPs. This study provides a proof of concept to generate functionalized DCPs using bioproduction, providing a potential solution to alleviate the reliance on hazardous chemicals, reduce the cost, and expedite the timeline for DCP discovery.