Fire extinguishing efficiency of perfluoro-isohexenes

2021 ◽  
pp. 47-53
Author(s):  
Павел Сергеевич Копылов
Keyword(s):  
Fire Suppression ◽  
Point Of View ◽  
Flammability Limits ◽  
Gaseous Mixtures ◽  
Atmospheric Lifetime ◽  
New Approach ◽  
Fire Extinguishing ◽  
Fire Suppressants ◽  
High Boiling Point ◽  
Better Than

Показана нехватка современных веществ для газового пожаротушения, вызванная борьбой с глобальным потеплением. Описаны подходы к поиску перспективных газовых огнетушащих веществ (ГОТВ), применявшиеся ранее. Предложен новый подход и найдены с его помощью принципиально новые огнетушащие вещества, полностью удовлетворяющие современным экологическим и токсикологическим требованиям. The paper is devoted to investigation of perfluoro-isohexenes as new gaseous fire suppressants. The current situation in the field of fire protection with chemically active gases is analyzed. The problem of greenhouse gases replacement during fire suppression is discussed. The disadvantage of existing alternative agents is short atmospheric lifetime. It is also shown that the existing approach to development of new gaseous fire extinguishing substances is almost exhausted. New group of gaseous agents for fire suppression - perfluoro-isohexenes - is proposed based on new approach. These substances are non-toxic and have very short atmospheric lifetime. Two types of experimental equipment were used in this work to investigate properties of aforesaid substances as extinguishing agents. It was implemented to determine flammability limits of gaseous mixtures and fire extinguishing concentration of gaseous fire suppressants having high boiling point. It was shown that perfluoro-isohexenes are non-flammable and their extinguishing properties are substantially better than properties of the nearest equivalent - perfuoroethyl-isopropylketone. These results are discussed from the point of view of the features of transformation of considered fire extinguishing substances in a flame.

A new approach based on graph matching and evolutionary approach for sport scheduling problem

2020 ◽  
pp. 1-16
Author(s):  
Meriem Khelifa ◽  
Dalila Boughaci ◽  
Esma Aïmeur
Keyword(s):  
Graph Matching ◽  
State Of The Art ◽  
Travel Cost ◽  
Round Robin ◽  
New Approach ◽  
Traveling Tournament Problem ◽  
Significant Interest ◽  
National League ◽  
Better Than

The Traveling Tournament Problem (TTP) is concerned with finding a double round-robin tournament schedule that minimizes the total distances traveled by the teams. It has attracted significant interest recently since a favorable TTP schedule can result in significant savings for the league. This paper proposes an original evolutionary algorithm for TTP. We first propose a quick and effective constructive algorithm to construct a Double Round Robin Tournament (DRRT) schedule with low travel cost. We then describe an enhanced genetic algorithm with a new crossover operator to improve the travel cost of the generated schedules. A new heuristic for ordering efficiently the scheduled rounds is also proposed. The latter leads to significant enhancement in the quality of the schedules. The overall method is evaluated on publicly available standard benchmarks and compared with other techniques for TTP and UTTP (Unconstrained Traveling Tournament Problem). The computational experiment shows that the proposed approach could build very good solutions comparable to other state-of-the-art approaches or better than the current best solutions on UTTP. Further, our method provides new valuable solutions to some unsolved UTTP instances and outperforms prior methods for all US National League (NL) instances.

ENHANCEMENT OF SCREEN FILM MAMMOGRAM UP TO A LEVEL OF DIGITAL MAMMOGRAM: EXPERIMENTAL ANALYSIS

2013 ◽  
Vol 13 (02) ◽  
pp. 1340004
Author(s):  
APARNA NARENDRA BHALE ◽  
MANISH RATNAKAR JOSHI
Keyword(s):  
Experimental Analysis ◽  
Breast Imaging ◽  
Point Of View ◽  
Quality Analysis ◽  
Digital Mammogram ◽  
Total Recovery ◽  
Clinical Observations ◽  
Opinion Score ◽  
Better Than

Breast cancer is one of the major causes of death among women. If a cancer can be detected early, the options of treatment and the chances of total recovery will increase. From a woman's point of view, the procedure practiced (compression of breasts to record an image) to obtain a digital mammogram (DM) is exactly the same that is used to obtain a screen film mammogram (SFM). The quality of DM is undoubtedly better than SFM. However, obtaining DM is costlier and very few institutions can afford DM machines. According to the National Cancer Institute 92% of breast imaging centers in India do not have digital mammography machines and they depend on the conventional SFM. Hence in this context, one should answer "Can SFM be enhanced up to a level of DM?" In this paper, we discuss our experimental analysis in this regard. We applied elementary image enhancement techniques to obtain enhanced SFM. We performed the quality analysis of DM and enhanced SFM using standard metrics like PSNR and RMSE on more than 350 mammograms. We also used mean opinion score (MOS) analysis to evaluate enhanced SFMs. The results showed that the clarity of processed SFM is as good as DM. Furthermore, we analyzed the extent of radiation exposed during SFM and DM. We presented our literally findings and clinical observations.

Numerical Simulation and Experimental Study on Water Mist Fire Suppression for Cooking Fog Discharge Pipe

2014 ◽  
Vol 915-916 ◽  
pp. 356-361
Author(s):  
Zheng Wen Xie
Keyword(s):  
Design Method ◽  
Fire Suppression ◽  
Orthogonal Design ◽  
Water Mist ◽  
Simulation Software ◽  
Droplet Radius ◽  
Test Analysis ◽  
Injection Angle ◽  
Fire Extinguishing ◽  
Flow Quantity

FDS simulation software was used to establish the full size lampblack physics model of single wind pipe, using the orthogonal design method design of analog calculation conditions, research in the nozzle pressure, the droplet radius, nozzle, flow quantity and injection angle parameters under different conditions of water mist fire extinguishing effect. Based on a full-scale combustion and water mist fire extinguishing experiment, the water mist fire suppression was observed and test analysis etc, to better understand the flue water mist fire extinguishing feasibility, provides the theory basis for the design of efficient, reliable flue fire extinguishing system.

scholarly journals Controllability and Observability of a Large Scale Thermodynamical System via Connectability Approach

2010 ◽  
Author(s):  
Virdiansyah Permana ◽  
Rahmat Shoureshi
Keyword(s):  
Graph Theory ◽  
Lie Algebra ◽  
Large Scale ◽  
Point Of View ◽  
Rank Condition ◽  
Computational Point ◽  
New Approach ◽  
Class System ◽  
Necessary And Sufficient ◽  
Controllability And Observability

This study presents a new approach to determine the controllability and observability of a large scale nonlinear dynamic thermal system using graph-theory. The novelty of this method is in adapting graph theory for nonlinear class and establishing a graphic condition that describes the necessary and sufficient terms for a nonlinear class system to be controllable and observable, which equivalents to the analytical method of Lie algebra rank condition. The directed graph (digraph) is utilized to model the system, and the rule of its adaptation in nonlinear class is defined. Subsequently, necessary and sufficient terms to achieve controllability and observability condition are investigated through the structural property of a digraph called connectability. It will be shown that the connectability condition between input and states, as well as output and states of a nonlinear system are equivalent to Lie-algebra rank condition (LARC). This approach has been proven to be easier from a computational point of view and is thus found to be useful when dealing with a large system.

scholarly journals Hydrological Validation of a Radar-Based Nowcasting Technique

2005 ◽  
Vol 6 (4) ◽  
pp. 532-549 ◽  
Author(s):  
Marc Berenguer ◽  
Carles Corral ◽  
Rafael Sánchez-Diezma ◽  
Daniel Sempere-Torres
Keyword(s):  
Point Of View ◽  
Motion Field ◽  
Warning Systems ◽  
Rainfall Runoff ◽  
Weather Radars ◽  
Radar Echoes ◽  
Radar Measurements ◽  
Rainfall Runoff Model ◽  
Runoff Model ◽  
Better Than

Abstract Nowcasting precipitation is a key element in the anticipation of floods in warning systems. In this framework, weather radars are very useful because of the high resolution of their measurements both in time and space. The aim of this study is to assess the performance of a recently proposed nowcasting technique (S-PROG) from a hydrological point of view in a Mediterranean environment. S-PROG is based on the advection of weather radar fields according to the motion field derived with an algorithm based on tracking radar echoes by correlation (TREC), and it has the ability of filtering out the most unpredictable scales of these fields as the forecasting time increases. Validation of this nowcasting technique was done from two different perspectives: (i) comparing forecasted precipitation fields against radar measurements, and (ii) by means of a distributed rainfall runoff model, comparing hydrographs simulated with a hydrological model using rainfall fields forecasted by S-PROG against hydrographs generated with the model using the entire series of radar measurements. In both cases, results obtained by a simpler nowcasting technique are used as a reference to evaluate improvements. Validation showed that precipitation fields forecasted with S-PROG seem to be better than fields forecasted using simpler techniques. Additionally, hydrological validation led the authors to point out that the use of radar-based nowcasting techniques allows the anticipation window in which flow estimates are forecasted with enough quality to be sensibly extended.

scholarly journals Summary of a Report on a Survey of the Fal Estuary Oyster Beds: (November, 1924),: With Notes on the Biology of the Oyster (O. edulis)

1927 ◽  
Vol 14 (3) ◽  
pp. 615-628 ◽  
Author(s):  
J. H. Orton ◽  
D. Bartley Stevenson
Keyword(s):  
Point Of View ◽  
Large Majority ◽  
Average Growth ◽  
Fair Proportion ◽  
Pass Through ◽  
Better Than

The spatfall in 1924, as in 1923, was very slight and from the point of view of the oyster-producer was a failure, and was little better in 1922.The growth of oysters in the summer of 1924 was unusually great; this has had the effect of bringing a large proportion of small oysters to a legally takeable size.The dredging results have, therefore, been much better than they were expected to be in the season of 1924–25, but the effect has been to deplete the beds still more of reserve stocks of small.Practically all the present stocks of small oysters are of a size between 2 and 2½ inches.With only average growth in 1925 and 1926 a large majority of these small oysters will have attained a size which will not pass through a 2½-inch ring; hence the beds are in a dangerous state.If, therefore, dredging continues under the present conditions, almost the whole of the present stock of small will have grown to large oysters and be cleared off the beds in the season of 1926–27.It is shown that although oysters may grow to a size of 2½ inches at Falmouth in small numbers in three summers, yet four summers are required before a fair proportion of spat can be expected to attain a size of 2½ inches.

scholarly journals New Cancer Stochastic Models Involving Both Hereditary and Nonhereditary Cancer Cases: A New Approach

2013 ◽  
Vol 2013 ◽  
pp. 1-19
Author(s):  
Wai-Yuan Tan ◽  
Hong Zhou
Keyword(s):  
Cancer Incidence ◽  
Stochastic Models ◽  
Biological Information ◽  
Cancer Genes ◽  
New Approach ◽  
Human Cancers ◽  
Seer Data ◽  
Sampling Procedures ◽  
And Control ◽  
Better Than

To incorporate biologically observed epidemics into multistage models of carcinogenesis, in this paper we have developed new stochastic models for human cancers. We have further incorporated genetic segregation of cancer genes into these models to derive generalized mixture models for cancer incidence. Based on these models we have developed a generalized Bayesian approach to estimate the parameters and to predict cancer incidence via Gibbs sampling procedures. We have applied these models to fit and analyze the SEER data of human eye cancers from NCI/NIH. Our results indicate that the models not only provide a logical avenue to incorporate biological information but also fit the data much better than other models. These models would not only provide more insights into human cancers but also would provide useful guidance for its prevention and control and for prediction of future cancer cases.

An Improved Wavelet Threshold De-Noising Data Processing Method Research in Deformation Monitoring

2011 ◽  
Vol 90-93 ◽  
pp. 2858-2863
Author(s):  
Wei Li ◽  
Xu Wang
Keyword(s):  
Data Processing ◽  
Deformation Monitoring ◽  
Processing Method ◽  
Threshold Function ◽  
Wavelet Coefficients ◽  
New Approach ◽  
Data Processing Method ◽  
Soft Threshold ◽  
Fixed Bias ◽  
Better Than

Due to the soft and hard threshold function exist shortcomings. This will reduce the performance in wavelet de-noising. in order to solve this problem，This article proposes Modulus square approach. the new approach avoids the discontinuity of the hard threshold function and also decreases the fixed bias between the estimated wavelet coefficients and the wavelet coefficients of the soft-threshold method．Simulation results show that SNR and MSE are better than simply using soft and hard threshold，having good de-noising effect in Deformation Monitoring.

scholarly journals On the asymptotic behavior of flood peak distributions

2006 ◽  
Vol 10 (2) ◽  
pp. 233-243 ◽  
Author(s):  
E. Gaume
Keyword(s):  
Frequency Distribution ◽  
Return Period ◽  
Asymptotic Properties ◽  
Flood Frequency ◽  
Point Of View ◽  
Rainfall Runoff ◽  
New Approach ◽  
Flood Peak ◽  
Flood Quantiles ◽  
The Impact

Abstract. This paper presents some analytical results and numerical illustrations on the asymptotic properties of flood peak distributions obtained through derived flood frequency approaches. It confirms and extends the results of previous works: i.e. the shape of the flood peak distributions are asymptotically controlled by the rainfall statistical properties, given limited and reasonable assumptions concerning the rainfall-runoff process. This result is partial so far: the impact of the rainfall spatial heterogeneity has not been studied for instance. From a practical point of view, it provides a general framework for analysis of the outcomes of previous works based on derived flood frequency approaches and leads to some proposals for the estimation of very large return-period flood quantiles. This paper, focussed on asymptotic distribution properties, does not propose any new approach for the extrapolation of flood frequency distribution to estimate intermediate return period flood quantiles. Nevertheless, the large distance between frequent flood peak values and the asymptotic values as well as the simulations conducted in this paper help quantifying the ill condition of the problem of flood frequency distribution extrapolation: it illustrates how large the range of possibilities for the shapes of flood peak distributions is.

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