Suppression System Research Articles

Adaptive repetitive control of wrist tremor suppression based on functional electrical stimulation

Tremor is an involuntary and repetitive swinging movement of limb, which can be regarded as a periodic disturbance in tremor suppression system based on functional electrical stimulation (FES). Therefore, using repetitive controller to adjust the level and timing of FES applied to the corresponding muscles, so as to generate the muscle torque opposite to the tremor motion, is a feasible means of tremor suppression. At present, most repetitive control systems based on FES assume that tremor is a fixed single frequency signal, but in fact, tremor may be a multi-frequency signal and the tremor frequency also varies with time. In this paper, the tremor data of intention tremor patients are analyzed from the perspective of frequency, and an adaptive repetitive controller with internal model switching is proposed to suppress tremor signals with different frequencies. Simulation and experimental results show that the proposed adaptive repetitive controller based on parallel multiple internal models and series high-order internal model switching can suppress tremor by up to 84.98% on average, which is a significant improvement compared to the traditional single internal model repetitive controller and filter based feedback controller. Therefore, the adaptive repetitive control method based on FES proposed in this paper can effectively address the issue of wrist intention tremor in patients, and can offer valuable technical support for the rehabilitation of patients with subsequent motor dysfunction.

An active piezoelectric damping vibration control system for the sting used in wind tunnel

In wind tunnel tests, the cantilever sting supporting system often suffers from low-frequency and large-amplitude resonance due to its inherent low structural damping characteristic, resulting in the degradation of data quality and structural safety. To improve wind tunnel testing safety and data accuracy, this paper is dedicated to establish an active vibration control system using piezoelectric stack actuators. A novel methodology of vibration monitoring based on modal transformation, which uses measured strain and a Strain-to-Displacement Transformation (SDT) matrix to reconstruct dynamic displacement field, is proposed herein. Meanwhile, strain sensor positions are optimized by an improved Particle Swarm Optimization (PSO) algorithm to reduce systematic estimation errors of this method. Furthermore, a Back-Propagated Neutral Network (BPNN) is established to implement a self-adaptive control strategy. A series of verification tests are performed to demonstrate the validity of the proposed system. Experimental results indicate that the relative Root Mean Square Error (RMSE) between estimated vibration displacement and measured vibration displacement is less than 3%, and a vibration attenuation of over 14 dB/Hz is achieved in ground tests, proving the superiority of this intelligent active vibration suppression system.

Determining and Verifying the Operating Parameters of Suppression Nozzles for Belt Conveyor Drives

Drives in belt conveyors are critical components of the conveyor system, susceptible to various factors that can cause disruptions and energy losses. In underground mining conditions, the risk of drive fires is particularly hazardous. Therefore, it is necessary to develop highly effective fire suppression systems. However, there are no guidelines for designing such systems. This study presents a methodology for selecting and verifying the fire suppression systems for belt conveyor drives. The proposed AMIGA system for extinguishing fires on underground coal mine conveyor belts, incorporating spraying and water mist installations, is supported by a theoretical calculation methodology. This enables determining the number of required nozzles and flow rate for complete fire suppression. The development of a methodology for the selection and verification of the sprinkler system components utilized guidelines provided in the standard VdS 2109:2002-03 and the PN-EN 12845+A2 standard from 2010, while a novel approach is proposed for water mist parameters that has not been previously applied anywhere else, and is based on assessing the fire’s intensity and the persistent disruption of the energy balance of the combusted coal. The theoretical calculations for potential fire power facilitate the determination of the appropriate water flow rate for the spraying system to protect the upper belt drive. For the proposed AMIGA system, the potential fire power was calculated to be 10.33MJ/min. Based on this, the water flow rate for the spraying installation to protect the upper drive belt of the conveyor was established to be a minimum 37.5dm3/min, and 21.4dm3/min for the mist installation used to protect the space below the conveyor drive. In order to verify the developed methodology for parameter selection, on-site tests were conducted to verify the results. Tests were conducted on an AMIGA prototype suppression system integrated into a conveyor drive. The results demonstrate that the developed system is effective in extinguishing fires on the belt using the spraying installation, as well as under the conveyor belt drive using the water mist installation, within the entire supply pressure range ( 0.4MPa to 1.6MPa ).

Multidomain Synthesis of Optimal Vibration Suppression Systems

Abstract There are numerous design possibilities for vibration–suppression systems considering components from multiple domains (e.g., mechanical, hydraulic, pneumatic, electrical). Traditional vibration absorber design approach could only explore limited possibilities, of which the performance is away from optimal. Since the 2000s, network synthesis-based approach has been applied. It allows identification of optimal absorber properties represented by networks consisting of modeling elements (stiffness, damping, inertance), providing significant theoretical performance improvements. However, such improvements have not yet been realized in industry. This is because the following questions have not been answered: (1) What are the network-represented properties of the conventional absorber? (2) How can the optimal network-represented properties be realized considering multidomain physical components? This article provides a method for answering these questions by proposing a novel multidomain synthesis technique, allowing bidirectional transformation between networks and multidomain components. Building on this technique, a vibration–absorber design methodology is proposed, which can construct physical realizations of optimal absorbers considering multidomain components. Another contribution of this work is to propose a novel component, providing a hydraulic realization of compliance ‘embedded’ in a hydraulic network. This methodology is demonstrated using an automotive case study, where the constructed optimal hydraulic suspension provides 23% ride comfort enhancement over the conventional one.

Water Spray Fire Suppression Tests Comparing Gasoline-Fuelled and Battery Electric Vehicles

AbstractThe increased use of electric vehicles has raised a concern about the performance efficiency of water spray fire suppression systems (often denoted “drencher systems”) typically installed on ro–ro cargo and ro–ro passenger ships. A test series was conducted involving testing of two pairs of geometrically similar gasoline-fuelled and battery electric vehicles in test conditions as equivalent as possible. During testing, key parameters such as the heat release rate, the gas temperature above the vehicle and the surface temperature of target steel sheet screens at the sides of the vehicle were measured. Fire ignition was arranged in such a way that the gasoline fuel or the battery pack was involved at the initial stage of the fire. It is concluded that fires in the two types of vehicles are different but have similarities. However, a fire in a battery electric vehicle does not seem to be more challenging than a fire in a gasoline-fuelled vehicle for a drencher system designed in accordance with current international recommendations.

A novel brace-damper system for seismic response suppression of high-rise steel frame structures

A novel brace-damper system for seismic response suppression of high-rise steel frame structures

Development and Implementation of a RC Snubber to Suppress Breaker Arcing Present in High-Stored-Energy Superconducting Magnet Systems

Arc suppression Snubbers offer safety in high energy superconducting magnet systems. Large superconducting magnets may have arcing across their breakers at the moment of slow dump initiation resulting from a sudden current redistribution in the powering circuit. The ATLAS Experiment at CERN experiences such arcing with its 7.3 H Toroidal magnet powering circuit. To discharge the magnets, the current is redistributed to a parallel branch called the Run Down Unit (RDU) by means of a breaker. Due to the physical layout and other metallic components in the vicinity, the power supply and RDU branches have undesirable and unavoidable parasitic inductance, causing a voltage spike over the main breakers at the moment of opening. The resulting arcing deteriorates the breaker contacts, resulting in increased operating temperatures and a more frequent need for maintenance. The arc suppression system developed takes the form of an RC Snubber (Resistor-Capacitor). The Snubber offers the current a low-impedance path, thus smoothing out the current redistribution and suppressing the voltage spike. This initial charging period of the capacitors gives the current enough time to overcome the parasitic inductance, therefore allowing the RDU to smoothly ramp up without a sudden voltage spike. To test the concept, a 1/50th scale demonstrator was developed and showed successful results. After the demonstrator, endurance testing of the electrolytic capacitors was performed to ensure no degradation of the charging characteristics for an equivalent of 20 years of operation. The Snubber was manufactured and implemented with successful results on the ATLAS Toroidal powering circuit.

A Pilot Study to Assess the Feasibility of Comparing Ultra-High Pressure to Low-Pressure Fire Suppression Systems for a Simulated Indirect Exterior Attack

Financial and human resource challenges constrain firefighting in rural communities. This can limit the approaches that can be used in a given residential fire situation. Effective use of portable, lower-cost equipment that would require fewer personnel and less water could greatly benefit rural communities. This study was conducted to assess the feasibility of comparing ultra-high-pressure to low-pressure fire suppression systems at low flow rates. The conditions used simulated an indirect exterior attack through a window. A purpose-built burn room and standardized class A fires were used to compare ultra-high-pressure and low-pressure systems at low flow rates. Temperatures in the burn room were recorded for each condition in triplicate. While neither operating condition resulted in full extinguishment of the fire, the ultra-high-pressure trials saw decreases in the proportion of starting temperature that were faster and of greater magnitude than for the low-pressure trials. This compares with earlier research, simulating a transitional attack that saw similar patterns for temperature cooling but resulted in extinguishment. This preliminary testing provides evidence that the burn container and room, as well as instrumentation and fuel load configurations, are appropriate for more extensive testing of such equipment for exterior fire suppression.

A confinable female-lethal population suppression system in the malaria vector, Anopheles gambiae.

Malaria is among the world's deadliest diseases, predominantly affecting Sub-Saharan Africa and killing over half a million people annually. Controlling the principal vector, the mosquito Anopheles gambiae, as well as other anophelines, is among the most effective methods to control disease spread. Here, we develop a genetic population suppression system termed Ifegenia (inherited female elimination by genetically encoded nucleases to interrupt alleles) in this deadly vector. In this bicomponent CRISPR-based approach, we disrupt a female-essential gene, femaleless (fle), demonstrating complete genetic sexing via heritable daughter gynecide. Moreover, we demonstrate that Ifegenia males remain reproductively viable and can load both fle mutations and CRISPR machinery to induce fle mutations in subsequent generations, resulting in sustained population suppression. Through modeling, we demonstrate that iterative releases of nonbiting Ifegenia males can act as an effective, confinable, controllable, and safe population suppression and elimination system.

Fire probabilistic safety assessment of control room in TRIGA PUSPATI research reactor

An internal Fire Probabilistic Safety Assessment (FPSA) study was conducted in the control room of the TRIGA PUSPATI (RTP) research reactor. This study aims to determine the likelihood of a fire occurring in the control room of RTP and the probability of fire occurring after an accident loss of instrumentation and control (LOIC) to the core damage frequency (CDF) value. The quantification results of the CDF are compared between LOIC with fire-induced (LOIC-F) and without fire-induced (LOIC). A methodical strategy to identify potential fire hazards that includes the precise identification of the design area, the size of any opening compartments, the location of electrical cabinets and fire suppression systems, as well as the placement of any safety-related equipment was applied. Included is Failure Mode and Effect Analysis (FMEA), which determines failure modes and designates repercussions for each scenario. This research will contribute on providing essential information on status of fire in RTP’s control room as an insight of identifying any risk of fire scenario that may occur including investigation of current fire protection system sufficiency. In addition, a core damage end state of consequences of fire after an LOIC is also presented. The result of this research can be beneficial and creating awareness to the management as well as reactor operators in case of fire in the control room of RTP.

Changing local climate patterns through hail suppression systems: conflict and inequalities between farmers and wine producers in the Burgundy Region (France)

Meteorological hazards can lead farmers to resort to strategies such as weather modifications. In this paper, we study how the use of such strategies, in this case silver iodide ground generators aimed at protecting vineyards from hail, caused a conflict between farmers (wine producers and cattle breeders) in Burgundy, France. The conflict emerged as the installation of these generators coincided with 3 years of severe droughts (2018, 2019 and 2020), which incurred additional expenses and organisational difficulties for local cattle breeders and led them to suspect a potential link between the generators and the droughts. We followed a transdisciplinary research approach, based on local stakeholder input and their need to mitigate the negative impacts of the conflict. Based on this approach, we studied the links between generator use and precipitation, and carried out in-depth interviews to study farmers’ experiences of climate, generators and conflicts in the region. Whilst the climatic analysis shows no local or regional effects of the generators on precipitation volumes, the sociological study highlights the vulnerability of farmers to successive droughts, found to be part of a wider pattern of climate change based on water balance variables (temperature, precipitation, evapotranspiration potential, soil wetness index) over a long period (1959–2020). Our results suggest that the use of technical solutions to mitigate meteorological hazards, within a broader context of climate engineering, can lead to conflicts at the regional level, and that the climate change challenge in the context of agriculture requires a focus on wider social issues including vulnerability.

Smart chitosan-PLGA nanocarriers functionalized with surface folic acid ligands against lung cancer cells

Lung cancer is the second most prevalent and first killer cancer worldwide, and conventional approaches do not have enough ability to suppress it. Therefore, a novel targeted chitosan (CS)-poly lactic-co-glycolic acid (PLGA)-folic acid (FA) nanocarrier was developed for delivery of sorafenib (Sor) to lung cancer cells. The nanocarrier (CPSF) had a size of 30–40 nm with globular shapes. Surface charge and drug content of CPSF were ascertained at about 1.1 mV and 15 %, respectively. Controlled (4 % within 2 h) and pH-sensitive (18 % within 2 h at pH = 5.0) Sor release were observed for the nanocarrier. The MTT assay demonstrated a cell viability of 13 % after 24 h treatment with 400 nM CPSF in A549 cancer cells while it was 78 % in MSC normal cells. The qRT-PCR revealed >8 folds and 11 folds increase for Caspase9 and P53 genes after 5 h treatment with 100 nM (IC50) CPSF; but a reduction of 5 folds was observed for the Bcl2 gene. Besides, 57 % and 20 % apoptosis were attained in cell cycle arrest and apoptosis assays for CPSF, respectively. CPF indicated about 88 % internalization in cancer cells. These data prove that CPSF is a promising nanodelivery system for lung cancer suppression.

Tritium transport in the vacuum vessel pressure suppression system for helium cooled pebble bed

In the frame of the safety studies for the EU-DEMO reactor, attention is paid to the hydrogen concentration in the vacuum vessel and connected volumes since it would lead to a possible hazard of releasing tritium and activated dust. The risk of explosion cannot be excluded a priori if H2 stockpiles. For this reason, in both water (WCLL) and helium (HCPB) cooled breeding blanket concepts of EU-DEMO, the problem is under investigation with a cross-reference between the available technologies in fission (such as the Passive Autocatalytic Recombiners – PAR) and fusion application. In particular, the recent analyses pointed out the implementation of the PARs into the Vacuum Vessel Pressure Suppression System or linked systems.This paper evaluates the Hydrogen behavior (main mobilized tritium source term) for the Helium-Cooled Pebble Bed (HCPB) VVPSS concept. The analyses preliminary investigate the stratification of the hydrogen mass inventory inside the PSS. In particular, a MELCOR 1.8.6 model of the PSS, based on past activities aimed at dust transport and thermohydraulic analyses, is adopted. The paper also introduces the applicability of PAR technology in the operation range of fusion devices, analyzing the problem of the recombination rate due to the dilution of Hydrogen after a Helium blowdown.

LabVIEW-based fire extinguisher model based on acoustic airflow vibrations

In recent years, soundwave-based fire extinguishing systems have emerged as a promising avenue for fire safety measures. Despite this potential, the challenge is to determine the exact operating parameters for efficient performance. To address this gap, we present an artificial intelligence (AI)-enhanced decision support model that aims to improve the effectiveness of soundwave-based fire suppression systems. Our model uses advanced machine learning methods, including artificial neural networks, support vector machines (SVM) and logistic regression, to classify the extinguishing and non-extinguishing states of a flame. The classification is influenced by several input parameters, including the type of fuel, the size of the flame, the decibel level, the frequency, the airflow, and the distance to the flame. Our AI model was developed and implemented in LabVIEW for practical use.
 The performance of these machine learning models was thoroughly evaluated using key performance metrics: Accuracy, Precision, Recognition and F1 Score. The results show a superior classification accuracy of 90.893% for the artificial neural network model, closely followed by the logistic regression and SVM models with 86.836% and 86.728% accuracy, respectively. With this study, we highlight the potential of AI in optimizing acoustic fire suppression systems and offer valuable insights for future development and implementation. These insights could lead to a more efficient and effective use of acoustic fire extinguishing systems, potentially revolutionizing the practice of fire safety management

Bandgap and wave attenuation optimization of tetra-chiral metamaterial using PSO algorithm

The development of vibration suppression systems with desired efficiency and low cost is one of the significant challenges in engineering. In this study, a parametric lattice model is considered to analyze the wave mitigation features in the metamaterial based on a tetra-chiral topology of the periodic cell equipped with internal resonators. Bloch wave theorem and finite element method are employed to explore the bandgap of the structure and its wave mitigation features. Since the unit cell geometry can be designed to open and shift bandgaps, particle swarm optimization algorithm is used to find the largest possible gap in the desired frequency range. The optimization method is programmed using MATLAB combined with an in-house finite element solver, considering the parameters' ranges to ensure geometric compatibility. In all studied cases, the optimized geometry leads to superior vibration suppression and larger complete bandgaps.

Fire Detection and Spatial Localization Approach for Autonomous Suppression Systems Based on Artificial Intelligence

Fire Detection and Spatial Localization Approach for Autonomous Suppression Systems Based on Artificial Intelligence

Intelligent vibration control for ultra-high-speed elevators: A type 2 variable universe fuzzy neural network method with input saturation

When elevators accelerate to ultra-high speed, the horizontal vibration suppression is significantly challenged by the complex coupled excitation and uncertain time-varying parameters. Therefore, this paper proposes an intelligent control method with type 2 variable universe fuzzy neural network considering input saturation. Firstly, considering the multilevel relationship of the guide rails, guide shoes, frame and car, a horizontal vibration dynamic model is constructed. To improve the tolerance and adaptability of the control system to the uncertain parameters, the type 2 variable universe fuzzy control is used as the main controller. The discourse of universe is adjusted by the T-S fuzzy neural network, and the anti-saturation controller is designed to compensate for the over-saturation problem aggravated by the networks. The non-parametric inverse model of intelligent adjustable dampers represented by the magnetorheological damper is constructed to accurately calculate the ideal output damping force. The effectiveness of the proposed control method is verified by the elevator experimental data and the bidirectional gas-solid coupling aerodynamic excitation. The results show that the proposed intelligent control method can significantly improve the mean values, peak values and comfort indexes of the horizontal vibration acceleration and tilt angle acceleration of the elevator car. The research provides a new intelligent control scheme for high-speed/ultra-high-speed elevators and other similar vibration suppression systems.

Mechanism Analysis of Airbag Explosion Suppression and Energy Absorption in a Flexible Explosion Suppression System

The unfixed flame propagation velocity of a gas explosion and the fixed response time of explosion suppression devices are the important reasons for the poor protective effect of active explosion suppression. A flexible explosion suppression method based on buffer energy absorption is detailed in this study. The explosion suppression system consists of an explosive characteristic monitoring system, an explosion suppression agent system, and an explosion suppression airbag. An empty pipe experiment and an explosion suppression experiment with a flexible-airbag gas-explosion suppression device were conducted in a 20.5 m-long pipe with an inner diameter of 180 mm. The flame propagation velocity and maximum overpressure values were compared between the two groups of experiments. The experimental results show that the flame wave propagation can be completely suppressed by the explosion suppression device under certain pressure. The occurrence time of maximum overpressure at each pressure measuring point is also analyzed. P3 is generally later than P4, which verifies the existence of energy absorption and explosion suppression effect of airbag. Finally, the energy absorption effect of the airbag is analyzed theoretically. The shock wave overpressure calculated in the sealing limit state of the airbag is 0.3432 MPa, and the maximum error is 7.8%, which provides reliable guidance and prediction for the experimental process in the future.

Analysis and compensation of frequency offset in co-site adjacent channel interference suppression

Due to the mismatch of the circuit oscillators, there will always be a frequency offset between the transmitter and the receiver. In the adjacent channel interference (ACI) suppression system using the reconstruction and cancellation method, the frequency offset decreases the accuracy of the reconstructed signal and introduces a time-varying term in the interference cancellation, resulting in poor performance of the ACI suppression. In this paper, the relationship between the normalized frequency offset, signal-to-noise ratio and the loss of interference suppression capability is analyzed through formula derivation and simulation. The validity of the frequency offset compensation method based on the pilot sequence is verified, and the relationship between the sequence length and the estimation accuracy is given. This paper provides necessary method reference and data support for the engineering of ACI suppression.

Jellyfish are sated thanks to GLWamide

At some point, we have all sat down to an excellent meal and after devouring as much as we could, no longer had the hankering to eat again for some time. So, what tells our bodies to stop eating? Hormones and chemicals in our brains called neurotransmitters guide the process of feeling full, but how far back in evolution did those processes become established? Vladimiros Thoma and colleagues from Tohoku University, Japan, with collaborators from other universities in Japan, set out to answer this very question by investigating the origins of these chemicals that control appetite in the jellyfish Cladonema pacificum.To identify the genes that regulate feeding in jellyfish, the team investigated which genes are activated or switched off during feeding by comparing famished with recently fed jellyfish. The researchers found that recently fed jellyfish increased the expression of several genes involved in nerve cell activity, leading the scientists to focus on proteins involved in communication between nerve cells. After testing 43 different proteins – a truly Herculean effort – the researchers narrowed the molecules that regulate satiety down to just a few, including one called GLWamide.When the Cladonema jellyfish feed, they ensnare prey such as brine shrimp with their tentacles, pull them back into their bell and ingest the shrimp. To see what part of this feeding ritual GLWamide impacted, the researchers measured how effectively the jellyfish captured their prey and how swiftly their tentacles retracted if the jellyfish were given GLWamide while still hungry. Thoma and colleagues found that hungry jellyfish were not as good at capturing prey when given GLWamide, but they were still better than jellyfish that had just eaten. The hungry animals dosed with GLWamide delayed tentacle contraction when they were fed just like the ones that had already had their fill. This suggests that GLWamide is an appetite suppressor that stops the tentacles from contracting. Next, the team wanted to see where the GLWamide was produced in the jellyfish's body and whether the levels of GLWamide changed based on when the jellyfish were fed. The researchers found that levels of GLWamide in the base of the tentacle increased 3–6 h after feeding, which may be how it suppressed the appetite of the jellyfish.Finally, the team wanted to explore the possibility that GLWamide represents an ancestral signalling system for appetite suppression in all animals. To do this, the researchers looked at a related chemical, called myoinhibitory peptide, in fruit flies. When the hungry jellyfish were given fruit fly myoinhibitory peptide, it reduced the jellyfish's appetite. Additionally, when the researchers gave fruit flies GLWamide, it reduced their appetites as well, showing that GLWamide represents an ancestral signal for appetite suppression. Thoma and colleagues also point out the importance of investigating the function of these chemicals in even more ancient animals than jellyfish, such as single-celled organisms, to discover the true origin of these appetite-suppressing systems. So, the next time you are feeling full after a huge meal, know that your body is working just like it has been programmed to for millions of years.