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Calculation of fire extinguishment time with water mist in an enclosed room

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Journal of Thermal Science 2010年第6期19卷 561-566页

作者： Lijun Yang Jianbo Zhao Zhenyu Xu School of Astronautics Beijing University of Aeronautics and Astronautics Beijing 100191 China Naval academy of armament Beijing 100161 China

The fire extinguishment time is a major factor to evaluate the efficiency of fire extinguishment with water mist. In this paper the fire extinguishment time with water mist in an enclosed room is calculated. Before adding water mist, the chemical kinetics plays the role in combustion, where a dimensionless math model is established by us-ing the Semenov theory. After adding water mist, the diffusion plays the role instead. Then another math model containing water mist and dominated by oxygen concentration is established. The fire temperature is integrated from Tm to extinguishment temperature TB and the extinguishment time can be obtained. The calculated values are compared with the experimental data under different conditions. The results show that this model can predict the fire extinguishment time accurately. Besides, this model also can be used to determine the critical water mist flux and evaluate which fire extinguishment mechanisms dominate the extinguishment.

关键词： extinguishment time minimum flux water mist

Chaff Cloud Jamming Suppression Based on Wavelet Transform

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Journal of Shanghai Jiaotong university(Science) 2011年第6期16卷 704-707页

作者：赵海波裴晋泽赵雷鸣胡光锐 Naval academy of armament Department of Electronic Engineering Shanghai Jiaotong University

Radar target signals and chaff cloud jamming signals have different characters by the wavelet *** wavelet coefficients of radar target signals are highly correlated with its near-and-near-scale wavelet coefficients,however the correlativity between the wavelet coefficients of chaff cloud jamming signals and its nearand-near scale wavelet coefficients is less *** on the binary-base discrete wavelet transform and the correlation algorithm,the method of target entropy to estimate standard variance of the jamming signals and each scale is proposed to ensure reasonable threshold,to suppress chaff cloud signals and finally to reconstruct mixed signals by the improved spatially selective noise filtration(ISSNF) *** extensive simulation results show that the proposed method can availably suppress chaff cloud jamming and decontaminate target echo.

关键词： wavelet transform target entropy improved spatially selective noise filtration(ISSNF) jamming suppression

A cloud Bayesian network approach to situation assessment of scouting underwater targets with fixed-wing patrol aircraft

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CAAI Transactions on Intelligence Technology 2023年第2期8卷 532-545页

作者： Yongqin Sun Peibei Ma Jinjin Dai Dongxin Li The 91206th Unit of PLA QingdaoChina navy Aviation University YantaiChina navy Submarine academy QingdaoChina

The battlefield situation changes rapidly because underwater targets'are concealment and the sea environment is ***,a great number of situation information greatly increase,which need to be dealt with in the course of scouting underwater *** assessment in sea battlefield with a lot of uncertain information is studied,and a new situation assessment method of scouting underwater targets with fixed-wing patrol aircraft is proposed based on the cloud Bayesian network,which overcomes the deficiency of the single cloud model in reasoning ability and the defect of Bayesian network in knowledge ***,in the method,the cloud model knowledge deal with the input data of Bayesian network reasoning,and the advantages in knowledge representation of cloud theory and reasoning of Bayesian network are applied;also,the fuzziness and stochasticity of cloud theory in knowledge expression,the reasoning ability of Bayesian network,are ***,the situation assessment model of scouting underwater targets with fixed-wing patrol aircraft is ***,the directed acyclic graph of Bayesian network structure is constructed and the assessment index is ***,the cloud model is used to deal with Bayesian network,and the discrete Bayesian network is ***,after CPT of each node and the transformation between certainty degree and probability are accomplished;the final situation level is obtained through a probability synthesis ***,the target type and the operational intention of the other side are deduced to form the battlefield ***,simulations are carried out,and the rationality and validity of the proposed method are testified by simulation *** this method,the battlefield situation can be *** this method has a wider application range,especially for large sample data processing,and it has better practicability.

关键词： certainty degree cloudy bayesian network(CBN) conditional probability table(CPT) fixed-wing patrol aircraft scouting underwater targets situation assessment

Particle flters for probability hypothesis density flter with the presence of unknown measurement noise covariance

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维普期刊数据库

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Chinese Journal of Aeronautics 2013年第6期26卷 1517-1523页

作者： Wu Xinhui Huang Gaoming Gao Jun College of Electronic Engineering Naval University of Engineering Automatization of Command Institute Academy of Navy Equipment

In Bayesian multi-target fltering,knowledge of measurement noise variance is very *** mismatches in noise parameters will result in biased *** this paper,a new particle flter for a probability hypothesis density（PHD）flter handling unknown measurement noise variances is *** approach is based on marginalizing the unknown parameters out of the posterior distribution by using variational Bayesian（VB）***,the sequential Monte Carlo method is used to approximate the posterior intensity considering non-linear and non-Gaussian *** other particle flters for this challenging class of PHD flters,the proposed method can adaptively learn the unknown and time-varying noise variances while *** results show that the proposed method improves estimation accuracy in terms of both the number of targets and their states.

关键词： Multi-target tracking(MTT) Parameter estimation Probability hypothesis density Sequential Monte Carlo Variational Bayesian method

Numerical Reality Method of the Microburst Model

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Journal of Donghua University(English Edition) 2015年第4期32卷 597-601页

作者：陶杨韩维 Naval academy of armament Department of Airborne Vehicle Engineering Naval Aeronautical and Astronautical University

An engineering microburst model to generate the microburst wind field for virtual flight simulation has been presented. The model is built as a finite viscosity vortex core model based on the vortex ring theory considering the air viscosity,and it can solve the problem of induced velocity discontinuity at the inner region near the vortex core. Moreover,the central axis velocity is obtained by turbulence free jet theory so as to avoid the *** parameters in multiple-vortex-ring microburst model are determined by improved quantum genetic algorithm( QGA) based on immune and mutation operator,and the parameters optimization of the model under condition of different maximum vertical velocity are investigated. The results show that the microburst model is effective and accurate. The simulation results fit the preset value very well,and the error is controlled within 10^(- 7).

关键词： microburst vortex ring viscosity vortex core quantum genetic algorithm(QG A) immune and mutation operator multiplevortexring model

Time-Series Forecasting Using Autoregression Enhanced k-Nearest Neighbors Method

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Journal of Shanghai Jiaotong university(Science) 2013年第4期18卷 434-442页

作者：潘峰赵海波刘华山 School of Information Science and Technology Donghua University Institute of Aircraft Equipment Naval Academy of Armament

This study proposes two metrics using the nearest neighbors method to improve the accuracy of time-series forecasting. These two metrics can be treated as a hybrid forecasting approach to combine linear and non-linear forecasting techniques. One metric redefines the distance in k-nearest neighbors based on the coefficients of autoregression (AR) in time series. Meanwhile, an improvement to Kulesh's adaptive metrics in the nearest neighbors is also presented. To evaluate the performance of the two proposed metrics, three types of time-series data, namely deterministic synthetic data, chaotic time-series data and real time-series data, are predicted. Experimental results show the superiority of the proposed AR-enhanced k-nearest neighbors methods to the traditional k-nearest neighbors metric and Kulesh's adaptive metrics.

关键词： time series forecasting nearest neighbors method autoregression (AR) metrics

Analysis of flame spread over aviation kerosene

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Chinese Science Bulletin 2010年第17期55卷 1822-1827页

作者： ZHOU JieBo CHEN GuoQing LI PeiMing CHEN Bing WANG ChangJiang LU ShouXiang State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China navy armament Departments Beijing 100071 China

Flame spread behaviors and temperature rise of fuel surface were experimentally investigated. A series of tests on aviation kerosene pool fires were conducted by using the schlieren image system, micro-thermocouple and infrared thermal imager. The velocity evolutions of flame spread and surface flow under different initial fuel temperatures were discussed. The characteristics of fuel surface temperature rise were revealed, and it was found that the preheating effect of surface flow on fuel decreased with increasing initial fuel temperature.

关键词：航空煤油火焰蔓延燃料流量温度上升红外热成像仪微型热电偶火焰传播图像系统

Capturing uncertainties of the underwater acoustic environment based on an ocean-acoustic coupled model

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Chinese Journal of Acoustics 2015年第3期34卷 267-282页

作者： DA Lianglong GUO Wuhong ZHAO Jianxin FAN Peiqin navy Submarine academy

Considering the uncertain effects of temporal and spatial changes in the marine en- vironment on the underwater acoustic environment, we established an ocean-acoustic coupled numerical model and performed a parallel calculation. This model incorporated acoustic calcu- lations into the dynamic ocean, thereby achieving a dynamic forecasting and assessment of the acoustic environment. Furthermore, we adopted the ensemble prediction method to predict the vertical structure of temperature in a classic cross-section, the sound speed of the cross-section of the investigated sea area, and transmission losses. We gave the prediction errors of the sound speed profile as well as the 90% probability interval of transmission losses and the uncertainty histograms of the sound speeds, transmission losses, and sonar ranges at different depths and frequencies. The results reflected the influence of marine temporal and spacial variations on the uncertainties of the underwater acoustic environment, and the results also quantified the uncertainties of the underwater acoustic environment parameters. The experimental results indicate that the method used in this study is able to delineate and quantify the uncertainties of the underwater acoustic environment caused by marine dynamic changes.

关键词： Capturing uncertainties of the underwater acoustic environment based on an ocean-acoustic coupled model

The characteristics of frequency-time azimuth spectrum estimation by a vector hydrophone in shallow water

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Chinese Journal of Acoustics 2018年第1期37卷 1-17页

作者： DA Lianglong HOU Wenshu SUN Qindong navy Submarine academy

The mechanism of interaction between the energy flows of the far-field ship noise and the near-field platform is studied, and the characteristics of frequency-time azimuth spec- trum is discussed. Based on normal modes theory in acoustic vector fields, the model of the near-field platform is established, and the simulated result is similar to the investigation in shallow water. The frequency-time aziinuth spectrum of the energy flow is investigated by the vector hydrophone changes with frequency. The energy flow of the far-field ship noise interacts with the near-field platform, so four kinds of stripes are shown in the frequency4ime azimuth spectrum, which is the same with the investigation of sea trial. The estimation of direction of arrival appears inaccuracy, and varies with frequency. The main factor that affects the charac- teristics of frequency-time azimuth spectrum of resultant energy flow is the difference of sound pressure level. The estimation of the direction of arrival benefits from this when a number of sources exist in shallow water.

关键词： The characteristics of frequency-time azimuth spectrum estimation by a vector hydrophone in shallow water