scholarly journals An Improved Near-Field Computer Vision for Jet Trajectory Falling Position Prediction of Intelligent Fire Robot

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7029
Author(s):  
Jinsong Zhu ◽  
Lu Pan ◽  
Ge Zhao
Keyword(s):  
Computer Vision ◽  
Near Field ◽  
Error Variance ◽  
Average Error ◽  
Centroid Method ◽  
Fire Extinguishing ◽  
Jet Trajectory ◽  
Position Prediction ◽  
Length And Area ◽  
In Fire

An improved Near-Field Computer Vision (NFCV) system for intelligent fire robot was proposed that was based on our previous works in this paper, whose aims are to realize falling position prediction of jet trajectory in fire extinguishing. Firstly, previous studies respecting the NFCV system were briefly reviewed and several issues during application testing were analyzed and summarized. The improved work mainly focuses on the segmentation and discrimination of jet trajectory adapted to complex lighting environment and interference scenes. It mainly includes parameters adjustment on the variance threshold and background update rate of the mixed Gaussian background method, jet trajectory discrimination based on length and area proportion parameters, parameterization, and feature extraction of jet trajectory based on superimposed radial centroid method. When compared with previous works, the proposed method reduces the average error of prediction results from 1.36 m to 0.1 m, and the error variance from 1.58 m to 0.13 m. The experimental results suggest that every part plays an important role in improving the functionality and reliability of the NFCV system, especially the background subtraction and radial centroid methods. In general, the improved NFCV system for jet trajectory falling position prediction has great potential for intelligent fire extinguishing by fire-fighting robots.

scholarly journals Real-Time Monitoring of Jet Trajectory during Jetting Based on Near-Field Computer Vision

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 690 ◽  
Author(s):  
Jinsong Zhu ◽  
Wei Li ◽  
Da Lin ◽  
Ge Zhao
Keyword(s):  
Computer Vision ◽  
Prediction Model ◽  
Real Time ◽  
Processing Time ◽  
Near Field ◽  
Image Correction ◽  
Noise Elimination ◽  
Sensor Device ◽  
Jet Trajectory ◽  
Novel Method

A novel method of near-field computer vision (NFCV) was developed to monitor the jet trajectory during the jetting process, which was used to precisely predict the falling point position of the jet trajectory. By means of a high-resolution webcam, the NFCV sensor device collected near-field images of the jet trajectory. Preprocessing of collected images was carried out, which included squint image correction, noise elimination, and jet trajectory extraction. The features of the jet trajectory in the processed image were extracted, including: start-point slope (SPS), end-point slope (EPS), and overall trajectory slope (OTS) based on the proposed mean position method. A multiple regression jet trajectory range prediction model was established based on these trajectory characteristics and the reliability of the model was verified. The results show that the accuracy of the prediction model is not less than 94% and the processing time is less than 0.88s, which satisfy the requirements of real-time online jet trajectory monitoring.

scholarly journals A Study on the Effect of O2 Diffusion on the Retention Time of Inert Agents

2020 ◽  
Vol 10 (19) ◽  
pp. 6694
Author(s):  
GoonHo Kim ◽  
Ju-Hong Cha ◽  
Jee-Hun Jeong ◽  
Ho-Jun Lee
Keyword(s):  
Theoretical Model ◽  
Retention Time ◽  
Hold Time ◽  
Theoretical Models ◽  
Accurate Model ◽  
Fire Extinguishing ◽  
A Value ◽  
O2 Diffusion ◽  
In Fire ◽  
And Diffusion

Gaseous agents are widely used in fire extinguishing systems (FESs) when water extinguishing agents are unavailable. The extinguishing ability of the FES-gaseous agent is determined by the retention time (hold time) at which its concentration is maintained. In particular, the retention time of the inert agent is determined by the O2 inflow from the outside. However, current theoretical models for inert agents do not provide an accurate model for the diffusion of incoming O2. Specifically, because the theoretical equations do not include O2 diffusion or include too large a value, there is a large difference between the measured and theoretical retention times. Therefore, in this study, accurate O2 diffusion was verified through experimental and numerical analyses using three types of deactivators and reflected in the existing theoretical model. O2 diffusion was analyzed through the interface slope α and diffusion velocity vd. As a result, this proposed method can predict the retention time more accurately than existing theoretical models.

scholarly journals Contributions of the wall boundary layer to the formation of the counter-rotating vortex pair in transverse jets

2011 ◽  
Vol 676 ◽  
pp. 461-490 ◽  
Author(s):  
FABRICE SCHLEGEL ◽  
DAEHYUN WEE ◽  
YOUSSEF M. MARZOUK ◽  
AHMED F. GHONIEM
Keyword(s):  
Boundary Layer ◽  
Boundary Condition ◽  
Near Field ◽  
Vortex Pair ◽  
Transverse Jets ◽  
Vortical Structures ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Jet Trajectory ◽  
Counter Rotating Vortex Pair

Using high-resolution 3-D vortex simulations, this study seeks a mechanistic understanding of vorticity dynamics in transverse jets at a finite Reynolds number. A full no-slip boundary condition, rigorously formulated in terms of vorticity generation along the channel wall, captures unsteady interactions between the wall boundary layer and the jet – in particular, the separation of the wall boundary layer and its transport into the interior. For comparison, we also implement a reduced boundary condition that suppresses the separation of the wall boundary layer away from the jet nozzle. By contrasting results obtained with these two boundary conditions, we characterize near-field vortical structures formed as the wall boundary layer separates on the backside of the jet. Using various Eulerian and Lagrangian diagnostics, it is demonstrated that several near-wall vortical structures are formed as the wall boundary layer separates. The counter-rotating vortex pair, manifested by the presence of vortices aligned with the jet trajectory, is initiated closer to the jet exit. Moreover tornado-like wall-normal vortices originate from the separation of spanwise vorticity in the wall boundary layer at the side of the jet and from the entrainment of streamwise wall vortices in the recirculation zone on the lee side. These tornado-like vortices are absent in the case where separation is suppressed. Tornado-like vortices merge with counter-rotating vorticity originating in the jet shear layer, significantly increasing wall-normal circulation and causing deeper jet penetration into the crossflow stream.

scholarly journals TESTS OF FIRE EXTINGUISHING ABILITY OF ALUMINUM HYDROGEL WHEN EXTINGUISHING MODEL NATURAL GROUND FIRES

2020 ◽  
Vol 10 (1) ◽  
pp. 38-49
Author(s):  
Ol'ga Ivchenko ◽  
Kirill Pankin
Keyword(s):  
Aqueous Solutions ◽  
Sodium Sulfate ◽  
Unit Length ◽  
Chemical Properties ◽  
Natural Fire ◽  
Natural Fires ◽  
Fire Extinguishing ◽  
Length And Area ◽  
Effective Use ◽  
Physical And Chemical

Extinguishing natural fires largely depends on the effective use of fire extinguishers by firefighters. Nevertheless, there are objective limits to the fire extinguishing ability of known substances and materials, which cannot be overcome by either tactical or technological methods. In the work, a method for extinguishing ground fires using aluminum hydrogels with different concentrations as fire extinguishing compositions is proposed, which makes it possible to simultaneously realize three extinguishing methods: cooling, insulation, and combustion inhibition. Investigation of fire extinguishing ability of the selected fire extinguishing compositions has been carried out according to a specially developed technique that simulates formation and development of ground natural fire in experimental plots. Extinguishing efficiency was assessed by comparing the results of the total cost of extinguishing agents to a unit of length of the edge of the fire and a unit of area of the fire. It was shown that the best fire extinguishing ability has an aqueous solution of aluminum hydrogel with a concentration of 3.5-7 g/l. Fire extinguishing ability of aluminum hydrogels was investigated. The obtained results were compared with the fire extinguishing ability of water and aqueous solutions of sodium carbonate (soda) and sodium sulfate. The use of other aqueous solutions (soda and sodium sulfate) has not shown significant contribution to fire extinguishing. Therefore, fire extinguishing effect is completely due to the chemical composition and physical and chemical properties of aluminum hydrogel. Based on the data obtained, aluminum hydrogel costs per unit length and area of the fire, its lowest concentration, which retains the fire extinguishing effect and the technological conditions for its preparation and use, have been determined

scholarly journals An Approach for the Analysis of the Accessibility of Fire Hydrants in Urban Territories

2019 ◽  
Vol 8 (12) ◽  
pp. 587
Author(s):  
Raminta Raškauskaitė ◽  
Vytautas Grigonis
Keyword(s):  
Risk Management ◽  
Information Systems ◽  
Geographic Information Systems ◽  
Data Collection ◽  
Information Technologies ◽  
Fire Risk ◽  
Fire Extinguishing ◽  
Urban Territories ◽  
Efficient Planning ◽  
In Fire

Globally, fire causes considerable losses that can be alleviated by taking appropriate actions facilitated by systems supported by geo-information technologies. This research focuses upon the development of an approach for planning urban infrastructures, and particularly in the accessibility of fire hydrants. Accessibility of fire hydrants’ infrastructure in urban territories is one of the key elements in fire risk management and public safety. The main result of the research is a comprehensive and structured Geographic Information Systems (GISs)-based dataset for the fast and more efficient planning of fire hydrants in urban territories. The proposed framework for data collection and processing was used to determine the distribution of hydrants, location of fire brigade stations and areas and to demonstrate the capabilities of the existing municipal fire extinguishing systems in Vilnius City, Lithuania. Later on, research on fire hydrants’ accessibility, analysis of the location of protected and unprotected urban territories and marking of unprotected buildings, was carried out. The resulting map of unprotected urban territories can be of great benefit for understanding fire risks and offering more effective ways for fire risk management.

The Evolution of Gasses in Fire Suppression Systems to Promote Changes in Industrial Towards Global Sustainability

2021 ◽  
Vol 1025 ◽  
pp. 259-264
Author(s):  
Jum’azulhisham bin Abdul Shukor ◽  
Rahim Jamian ◽  
Azmi Hassan ◽  
Muhammad Al Hapis Abdul Razak
Keyword(s):  
Fire Suppression ◽  
Sudden Change ◽  
Montreal Protocol ◽  
Fire Extinguishing ◽  
Clean Agent ◽  
Key Issues ◽  
Greenhouse Effects ◽  
The Stability ◽  
Fundamental Equations ◽  
In Fire

The historical development of fire suppression technology evolved in the 1930s since the application of Halons as a fire extinguishing agent. The fire may cause tremendous losses to organizations. It affects the chain of businesses and the stability of the economic growth of a country. The key issues of greenhouse effects and safety and health as well contributes to the sudden change of the technology of fire extinguishing systems. The establishment of the Montreal Protocol and Kyoto Protocols controls the producers to develop, supply and use of environmentally hazardous gasses worldwide. Hence, promote global sustainable for upcoming generations. This paper is highlighting the reasons gas type fire extinguishing agents extensively used substituting conventional methods against fire. The fundamental equations of Ozone Depleting Potential and Global Warming Potential were properly discussed to show how severe these gasses exposed to the environment. The effectiveness of these gases as a clean agent in extinguishing the fire may convince prospect users to carry out the decision of changes. Potential extinguishing agents will be deliberated to investigate their needs as new fire suppression agents. It will be then to be suggested and recommended for further studies.

Study of Microscale Three-Dimensional Printing Using Near-Field Melt Electrospinning

2017 ◽  
Author(s):  
Xiangyu You ◽  
Chengcong Ye ◽  
Ping Guo
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Low Cost ◽  
Near Field ◽  
Three Dimensional ◽  
Thin Wall ◽  
Direct Writing ◽  
Melt Electrospinning ◽  
Wall Structures ◽  
Jet Trajectory

Three-dimensional (3D) printing of microscale structures with high resolution (sub-micron) and low cost is still a challenging work for the existing 3D printing techniques. Here we report a direct writing process via near-field melt electrospinning to achieve microscale printing of single filament wall structures. The process allows continuous direct writing due to the linear and stable jet trajectory in the electric near-field. The layer-by-later stacking of fibers, or self-assembly effect, is attributed to the attraction force from the molten deposited fibers and accumulated negative charges. We demonstrated successful printing of various 3D thin wall structures (freestanding single walls, double walls, annular walls, star-shaped structures, and curved wall structures) with a minimal wall thickness less than 5 μm. By optimizing the process parameters of near-field melt electrospinning (electric field strength, collector moving speed, and needle-to-collector distance), ultrafine poly (ε-caprolactone) (PCL) fibers have been stably generated and precisely stacked and fused into 3D thin-wall structures with an aspect ratio of more than 60. It is envisioned that the near-field melt electrospinning can be transformed into a viable high-resolution and low-cost microscale 3D printing technology.

Mathematical modeling of nitrogen-pressurized Halon flow in fire extinguishing systems

2021 ◽  
Vol 122 ◽  
pp. 103356
Author(s):  
Aitor Amatriain ◽  
Gonzalo Rubio ◽  
Ignacio Parra ◽  
Eusebio Valero ◽  
David Andreu ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Fire Extinguishing ◽  
In Fire

New techniques and a new approach to the effective extinguishing of fully developed fires in enclosed spaces

2016 ◽  
Vol 8 (1) ◽  
pp. 213-224
Author(s):  
Norbert Tuśnio ◽  
Paweł Wolny
Keyword(s):  
Fire Suppression ◽  
Radiant Heat ◽  
Fire Service ◽  
Water Mist ◽  
Abrasive Waterjet ◽  
Water Spray ◽  
Fire Extinguishing ◽  
Pressure Water ◽  
Fire Area ◽  
In Fire

An example of modern water mist extinguishing technology is presented in the article. Water mist systems are firefighting systems which uses very fine water sprays. The smallest water droplets allow a water mist to control, suppress or extinguish fires by cooling both the flame and hot gases by evaporation, displacing oxygen by evaporation and reducing radiant heat through the small droplets themselves. The effectiveness of water mist systems in fire suppression depends on its spray characteristics, which include the droplet size and distribution, flux density and spray dynamics, phase of fire development, fire size and the ventilation conditions. The COBRA (known as PyroLance in USA) systems presented use of a cutting extinguisher is a fire extinguishing technique that combines abrasive waterjet cutting with water spray extinguishing, through a single handpiece or nozzle. The firefighter approaches the fire from outside the main fire area, then uses the cutting action to drill a small hole through a barrier such as a door, wall, roof or floor. Switching to a water spray then allows the fire to be fought, as with a conventional fog nozzle. An analysis of the benefits of using high-pressure water mist in conjunction with new firefighting tactics is described. State Fire Service should aim to minimize water consumption and thus reduce the post-fire losses, take care of environmental protection and improve safety conditions for firefighters.

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