scholarly journals A Hybrid Algorithm for Gas Source Locating Based on Unmanned Vehicles in Dynamic Gas Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Yu Huang ◽  
Lei Li ◽  
Renxing Ji

A new method for locating hazardous gas source based on unmanned vehicles is presented in this paper. Based on the gas sensors and unmanned vehicles, the research on the gas source location algorithm, using the gas concentration of several detection sites as heuristic information, is carried out. When the available information is less, such that the gas diffusion model is unknown, the algorithm can locate the gas leakage source quickly. The proposed algorithm combines particle swarm optimization (PSO) and Nelder–Mead simplex method. Compared with the standard PSO, the proposed algorithm has fewer iterations and faster convergence speed. Finally, the feasibility of the algorithm is verified by digital simulation experiments.

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Ye Jiang ◽  
Shuyan Xiao ◽  
Jian Liu ◽  
Bo Chen ◽  
Bangbang Zhang ◽  
...  

In order to monitor the gas leakage, the gas sensors are deployed conventionally in chemical industry park, with little considerations given to the gas characteristics and weather conditions, which give rise to the problems of coverage hole and coverage repetition. To solve the problems, this paper proposes a deterministic sensor deployment method with the gas diffusion models which takes into account wind speed and direction and then studies the influence of wind speed and direction on the monitoring error of gas sensors. Then, we research the deterministic deployment method of gas sensors in condition of the main wind speed and direction somewhere. Firstly, we use the CFD theory to simulate the gas diffusion situation so as to obtain the concentration value of the relevant points. Secondly, we put forward a new optimization criterion, namely, the more alarm concentration points covered by gas sensors, the coverage performance is better, and the deployment method is better. Accordingly, a new objection function is built. Thirdly, we obtain the weight values of the function using entropy estimation method. Finally, we deploy the gas sensors determinately using particle swarm optimization (PSO) algorithm. The simulation results show that the proposed method can improve the monitoring efficiency and the coverage performance of gas sensor network.


2013 ◽  
Vol 726-731 ◽  
pp. 1354-1357
Author(s):  
Ning Zhou ◽  
Wei Cui ◽  
Kai Quan Wang ◽  
Hui Jun Zhao

Using Fluent to simulate dangerous heavy gas leakage and diffusion of oil tank farm under different conditions. The analysis results show that the diffusion processes of heavy gas can be divided into four stages like gravity settling stage, air entrainment stage, cloud heating stage and the stage of transformation to the non-heavy gas diffusion. While the gas leakage occurs in the middle position of the tank farm, the gas diffusion speed is slow and the gas concentration is easy to achieve the explosive limit. When the wind velocity is 0.95 m/s, the diffusion velocity of heavy gas increases with the wind velocity, gas concentrations rises obviously. When the wind velocity reaches to 1.7 m/s, the gas concentration will reach the peak, as the wind velocity increases, the gas concentration reduces slowly.


1969 ◽  
Vol 35 (4) ◽  
pp. 711-719 ◽  
Author(s):  
Paul H. Leblond

General qualitative rules are derived for the behaviour of the volume of an ascending spherical bubble and of the gas pressure within it. Three modes of behaviour are discerned, corresponding to as many possible orderings of the relative influences of ascent velocity, gas leakage and surface tension on the volume and the pressure balance. These general results are nearly independent of the particular forms of the ascent velocity and gas exchange functions. Quantitative results are presented for the Stokes law régime.


2009 ◽  
Vol 6 (4) ◽  
pp. 693-697
Author(s):  
Baghdad Science Journal

During of Experimental result of this work , we found that the change of electrical conductivity proprieties of tin dioxide with the change of gas concentration at temperatures 260oC and 360oC after treatment by photons rays have similar character after treatment isothermally. We found that intensive short duration impulse annealing during the fractions of a second leads to crystallization of the films and to the high values of its gas sensitivity.


MAUSAM ◽  
2021 ◽  
Vol 57 (2) ◽  
pp. 221-230
Author(s):  
O. P. SINGH ◽  
K. RUPA KUMAR ◽  
P. K. MISHRA ◽  
K. KRISHNA KUMAR ◽  
S. K. PATWARDHAN

Lkkj & bl 'kks/k&i= esa HkweaMyh; tyok;q ifjorZu ds ifj.kkeLo:i 'krkCnh ds e/; ¼2041&60½ ds nkSjku ,f’k;kbZ xzh"edkyhu ekulwu ds fof’k"V y{k.kksa dk iwokZuqeku djus ds mÌs’; ls vuqdj.k iz;ksxksa ds ifj.kke izLrqr fd, x, gSaA blds fy, gSMys tyok;q iwokZuqeku vkSj vuqla/kku dsUnz] ;w- ds- dk {ks=h; tyok;q ekWMy gSM vkj- ,e- 2 dk mi;ksx fd;k x;k gSA ,f’k;kbZ {ks= ds fy, 20 o"kksZa dh vof/k ds nks vuqdj.k iz;ksx fd, x, gSa uker% igyk] 1990 Lrjksa ds vuq:i xzhu gkml xSl lkanz.k dh fu/kkZfjr ek=k] ftls dUVªksy ¼lh- Vh- ,y-½ iz;ksx dgk x;k gS vkSj nwljk 1990 ls ysdj 2041&60 rd ds fy, xzhu gkml xSl lkanz.k ds okf"kZd feJ.k esa 1 izfr’kr dh o`f) lesr ftls vkxs xzhu gkml xSl ¼th- ,p- th-½ iz;ksx dgk x;k gSA xzhu gkml xSl lkanz.k esa okf"kZd feJ.k esa 1 izfr’kr dh o`f) tyok;q ifjorZu ds var% ljdkjh iSuy vkbZ- ih- lh- lh- }kjk rS;kj dh xbZ ;kstuk ls yh xbZ gSA bu iz;ksxksa ls 'krkCnh ds e/; ds nkSjku ,f’k;kbZ xzh"edkyhu ekulwu esa ik, tkus okys fof’k"V y{k.kksa esa gksus okys dqN ifjorZuksa dk irk pyk gS ftudk c<+s gq, ekuotfur mRltZdksa ds dkj.k gksuk LokHkkfor gSA lewph ekulwu _rq ds nkSjku Hkkjrh; {ks= ij fuEu {kksHk eaMy ¼850 gSDVkikLdy½ esa ekulwu nzks.kh ¼,e- Vh- ½ dk mRrj dh vksj lkekU; :i ls c<+uk lcls vf/kd egRoiw.kZ ifjorZu izrhr gksrk gSA vuqdj.k ifj.kkeksa ls ekulwu _rq ds nkSjku vjc lkxj esa leqnz Lrj nkc ¼,l- ,y- ih-½ esa yxHkx 1&2 gS- ik- dh o`f) dk irk pyk gS ftlds ifj.kkeLo:i fuEu {kksHk eaMy esa vlkekU; izfrpØokr gksrs gSaA bldk vFkZ ;g gqvk fd fuEu Lrjh; tsV ¼,y- ,y- ts-½ vkSj vjc lkxj esa ekulwu dh /kkjk det+ksj iM+ tkrh gSA ;g ekWMy m".krj leqnz lrg dh fLFkfr;ksa esa fgan egklkxj ds mRrj esa ekulwuh pØokrh; fo{kksHkksa dh vko`fr esa deh dks vuqdfjr djrk gS tks gky gh ds n’kdksa esa ekulwu ds vonkcksa dh vko`fr esa deh dh izo`fr;ksa ds vuq:i ikbZ xbZ gSA bu iz;ksxksa ls ;g irk pyrk gS fd ikfdLrku vkSj mlds lehiorhZ mRrjh if’peh Hkkjr ds Åij Å"ek fuEunkc rhoz gks ldrk gS vkSj ekulwu _rq           ds nkSjku FkksM+k iwoZ dh vksj c<+ ldrh gSA ;g ekWMy] Hkkjrh; leqnz ds nf{k.kh Hkkxksa esa 8° & 10° m- ds chp 100 gS- ik- ¼Vh- bZ- ts- dksj dk Lrj½ ij fo’ks"kdj ekulwu ds iwokZ)Z ds nkSjku m".kdfVca/kh; iwokZfHkeq[kh tsV¼Vh- bZ- ts-½ dks izHkkfor djrk gSA The paper presents the results of simulation experiments aimed at predicting the characteristic features of Asian Summer Monsoon during the middle of the century (2041-60) resulting from global climate change. The model used is HadRM2 regional climate model of the Hadley Centre for Climate Prediction and Research, UK. Two simulation experiments of 20 years length have been performed for the Asian domain, namely, one with a fixed amount of greenhouse gas concentration corresponding to 1990 levels called the 'control' (CTL) experiment and the other with the annual compound increase of 1 % in the greenhouse gas concentration for 2041-60 from 1990 onwards called the 'greenhouse gas' (GHG) experiment. The annual compound increment of 1 %, in the greenhouse gas concentration has been adopted from the projection given by the Intergovernmental Panel for Climate Change (IPCC). The experiments have brought out some of the changes in the characteristic features of mid-century Asian summer monsoons that are expected to occur due to increased anthropogenic emissions. The most significant change seems to be a general northward shift of the monsoon trough (MT) in the lower troposphere (850 hPa) throughout the monsoon season over the Indian region. The simulation results have shown an increase of about 1-2 hPa in the sea level pressure (SLP) over the Arabian Sea during the monsoon resulting in an anomalous anticyclone over there in the lower troposphere. This would mean the weakening of Low Level Jet (LLJ) and the Arabian sea branch of the monsoon current. The model has simulated a decrease in the frequency of the monsoonal cyclonic disturbances over the north Indian Ocean under the warmer sea surface conditions which conforms to the observed decreasing trends in the frequency of monsoon depressions in recent decades. The experiments have shown that the Heat Low over Pakistan and adjoining northwest India, may intensify and shift slightly eastward during the monsoon. The model has simulated the strengthening of Tropical Easterly Jet (TEJ) at          100 hPa (the location of TEJ core ) over the southern parts of Indian sea between 8° - 10° N, especially during the first half of the monsoon season.


2017 ◽  
Vol 16 (02) ◽  
pp. 1750013 ◽  
Author(s):  
S. Gomri ◽  
T. Contaret ◽  
J. Seguin ◽  
K. Aguir ◽  
M. Masmoudi

In this paper, we propose a new model of adsorption–desorption (AD) noise in chemoresistive gas sensors by taking into account the polycrystalline structure of the sensing layer and the effect of the adsorbed molecule’s density fluctuation on the grain boundary barrier height. Using Wolkenstein’s isotherm, in the case of dissociative and non-dissociative chemisorption, combined with the electroneutrality, we derive an exact expression for power density spectrum (PDS) of the AD noise generated around one grain. We show that the AD noise generated in the overall sensing layer is a combination of multi-Lorentzian components. The parameters of each Lorentzian depend on the nature of the detected gas, the grain size, and the gas concentration. Moreover, we show that, according to the sensing layer microstructure (distribution of grain sizes in the sensing layer), this combination can lead to a [Formula: see text] spectrum, and in this case the noise level of the [Formula: see text] spectrum depends on the nature of the detected gas. The noise modeling presented in this paper confirms that noise spectroscopy is a useful tool for improving the gas sensor selectivity.


2020 ◽  
Vol 305 ◽  
pp. 00035
Author(s):  
Nicolae Ioan Vlasin ◽  
Gheorghe-Daniel Florea

Gas-explosion events in the private or industrial field are usually followed by a technical analysis of the factors that led to their generation. In this respect, INCD INSEMEX Petroşani is accredited for conducting the technical expertise and for the elaboration of the Expertise Report. Starting with on-site findings and sampling, research continues at INCD INSEMEX laboratories, grouped on areas of interest in case management (electrical, ventilation, chemical, pyrotechnics, etc.). Determining the causes of the event implicitly involves establishing the probable source of initiation of the explosive mixture, after discovering the fuel gas source and analyzing how the mixture was formed. Due to the geometric complexity of the space in which the explosion occurred, incident, reflected or compound shock waves generated by explosion can create a footprint of the event that questions the location of the source of initiation. Depending on the possible sources found in the field, the INSEMEX Laboratory of Computational Simulations performs analyzes based on finite elements and finite volumes methods. The elements taken into account in the computational simulations concern both the geometry of the space, the nature of the combustible gas leakage, the dispersion of the gas, and the resulting thermal and mechanical effects.


Sign in / Sign up

Export Citation Format

Share Document