Evaluation and prediction of blast induced ground vibration using support vector machine

We present the application of Support Vector Machine (SVM) for the prediction of blast induced ground vibration by taking into consideration of maximum charge per delay and distance between blast face to monitoring point. To investigate the suitability of this approach, the predictions by SVM have been compared with conventional predictor equations. Blast vibration study was carried out at Magnesite mine of Pithoragarh, India. Total 170 blast vibrations data sets were recorded at different strate-gic and vulnerable locations in and around to mine. Out of 170 data sets, 150 were used for the training of the SVM network as well as to determine site constants of different conventional predictor equations, whereas, 20 new randomly selected data sets were used to compare the prediction capability of SVM network with conventional predictor equations. Results were compared based on Co-efficient of Determination (CoD) and Mean Absolute Error (MAE) between monitored and predicted values of Peak Particle Veloc-ity (PPV). It was found that SVM gives closer values of predicted PPV as compared to conventional predictor equations. The coef-ficient of determination between measured and predicted PPV by SVM was 0.955, whereas it was 0.262, 0.163, 0.337 and 0.232 by USBM, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations, respectively. The MAE for PPV was 11.13 by SVM, whereas it was 0.973, 1.088, 0.939 and 1.292 by USBM, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations respectively.

Spatial Distribution and Seasonal Variation of Explosive Cyclones over the North Atlantic

Spatial distribution and seasonal variation of explosive cyclones （ECs） over the North Atlantic from October 2000 to September 2016 are investigated using the reanalysis data of Final Analysis （FNL）, Mean Sea Level Pressure （MSLP） and Optimum Interpolation （OI） Sea Surface Temperature （SST） provided by the National Centers for Environmental Prediction （NCEP）, the European Centre for Medium-Range Weather Forecasts （ECMWF） and the National Oceanic and Atmospheric Administration （NOAA）, respectively. Considering the meridional distribution of ECs and 10-m height wind field associated with the ECs, the definition of EC given by Yoshida and Asuma （2004） is modified. It is found that the ECs occurred mainly in four regions during winter season, namely, North America continent （NAC）, the Northwest Atlantic （NWA）, the North-centzal Atlantic （NCA）, and the Northeast Atlantic （NEA）, depending on the spatial distribution of EC＇s maximum deepening rate of central sea level pressure （SLP）. According to the magnitude of maximum deepening rate, the trend of EC numbers basically decrease with the increase of EC＇s maximum deepening rate over the North Atlantic during the whole time period. Over the North Atlantic basin, for monthly statistics, the NEA, NCA, and NWA cyclones occur mainly in December, from December to March, and from January to February, respectively. NWA, NCA and NEA cyclones in winter are associated with low-level barocliincity, both low-level baroclinicity and upper-level forcing and upper-level forcing, respectively. According to monthly variation, the averaged maximum deepening rate of central SLP firstly increases and then decreases from July to June. Overall, the distribution of ECs＇ tracks is basically in the southwest-northeast direction. During winter circulation stage （from October to May）, the averaged maximum deepening rate of central SLP and the averaged minimum central SLP of ECs decrease, and the averaged explosive-deepening duration of ECs shortens from west to east over the North Atlantic basin. During summer circulation stage （from June to September）, the number of ECs is far less than that of winter circulation. NCA cyclones are the lowest in the average minimum central SLP of ECs, and the longest in the average explosive-deepening duration ofECs. NEA cyclones are the strongest in the average maximum deepening rate of central SLR

Pattern recognition prediction of coal and gas outburst hazard in the sixth mine of Hebi

Based on the systematical analysis influence factors of coal and gas outburst, the main factors and their magnitude was determined by the corresponding methods.With the research region divided into finite predicting units,the internal relation between the factors and the hazard of coal and gas outburst,that was combination model of influence factors,was ascertained through multi-factor pattern recognition method.On the basis of contrastive analysis the pattern of coal and gas outburst between prediction region and mined region,the hazard of every predication unit was determined.The mining area was then divided into coal and gas outburst dangerous area,threaten area and safe area re- spectively according to the hazard of every predication unit.Accordingly the hazard of mining area is assessed.

Prediction of rock-burst-threatened areas in an island coal face and its prevention:A case study

The island coal face arises in coal mines with the purpose of preventing gas explosion or maintaining the balance between mining and tunneling. However, its particular stress conditions in the surrounding rock may increase the difficulty of stress control in the coal face and in its mining roadways, especially when the coal seam, the roof, and the floor have rock-burst propensities, The high energy accumulated in the island coal face and in its roof and floor will intensify rock-burst propensity or even induce rock burst, which further result in great casualties and financial losses. Taking island coal face 2321 in Jinqiao coal mine as a case, we propose a method for the prediction of rock-burst-threatened areas in an island coal face with weak rock-burst propensity. Based on the anaHysis of the movement of the overlying roof and characteristics of stress distribution, this method combined numerical simulation with drilling bits to ensure the prediction accuracy. The effects of coal pillars with different widths on the mitigation of stress concentration in the coal face and on the prevention of rock burst are analyzed together with the mech- anism behind. Finally, corresponding measures against the rock burst in the island coal face are proposed.

Experimental study of flame microstructure and propagation behavior of mine-gas explosion

The high speed cameral and schlieren images methods were used to record the photograph of flame propagation process.Meanwhile,the ionization current probes were set up to detect the reaction intensity of the reaction zone.The characteristics of methane/air flame propagation and microstructure were analyzed in detail by the experi- mental results coupled with chemical reaction thermodynamics.The high speed schlieren image showed the transition from laminar flame to turbulence combustion.The ion current curves disclosed the reaction intensity and combustion characteristic of flame front.In the test,the particular tulip flame was formed clearly,which was induced to some extent by turbulent combustion.Based on the schlieren images and iron current result,it can be drawn that the small scale turbulence combustion also appears in laminar flame,which thickens the flame front,but makes little influence on the flame front shape.During the laminar-turbulent transition,the explosion pressure plays an important role on the flame structure change.

Existence of Explosive Solutions for a Class of Nonlinear Elliptic Equations

By the subsuper solutions method, the explosive supersolutions and explosive subsol utions are obtained and the exsistence of explosive solutions is proved on a bounded domain for a class of nonlinear elliptic problems.Then, the exsitence of an entire large solution is proved by the perturbed method.

On a Class of Nonlinear Wave Equations

This paper investigated the asymptotic behavior of global weak solutions of the initial boundary value problem for a class of nonlinear wave equations. Moreover, blowup of this kind of equations was also disscussed.

Numerical Simulation of Concrete Plate Damaged Under Explosive Loading

The grisliness after-effects can be induced by explosion accident with the collapsing of the structures, the demolishing of the equipments and the casualty of the human beings. Isolation belt constructed between the blast point and the construction is one of the useful design schemes for blast resistance. The nonlinear procedure ANSYS/LSDYNA970 is used to simulate the contact detonation and the isolation belt of blast resistance filled with the air or water respectively. The results indicate that the maximal damage can be caused by the contact detonation, and the isolation belt of blast resistent filled with water can reduce the damage greatly.

Experimental investigation of external explosion in the venting process

Experimental investigations were conducted on the process of combustion and explosion vent in a 200 mm (diame- ter)×400 mm (length) vertical cylindrical vessel. When CH4-air mixture gases were used and the vent diameter was 55 mm, conditions of Φ (equivalent ratio)=0.8, Φ=1.0 and Φ=1.3 and two ignition positions (at the cylinder center and bottom) were selected. The venting processes and the correlated factors are discussed in this paper.

Numerical computation algorithm of explosion equations and thermodynamics parameters of mine explosives

A new numerical algorithm is presented to simulate the explosion reaction process of mine explosives based on the equation of state, the equation of mass conservation and thermodynamics balance equation of explosion products. With the affection of reversible reaction of explosion products to explosion reaction equations and thermodynamics parameters considered, the computer program has been developed. The computation values show that computer simulation results are identical with the testing ones.

Calibrated explosive triangle for determining capacity of explosion of gas mixtures

Determination of the capacity for explosion of gas mixtures in a sealed area is very important for mining engineers.If this capacity is high,it would be very dangerous for rescue workers to proceed with their rescue operations.A number of methods have been developed to determine the capacity for explosion of gas mixtures in sealed areas.One of the more popular methods is the Coward explosive triangle,published by Coward.He presented a fast and easy way to determine the capacity for explosion of gas mixtures,which has proved to be a very useful tool for mining engineers and members of rescue teams.However,due to few drawbacks in this method;potential errors would be introduced when it is applied.In a brief introduction we first describe the Coward method and then,we propose and discuss new calibrated explosive triangles.We demonstrate the method in two case studies where we compare our results with those of the old model.The results indicate that the calibrated method have improved accuracy and reliability.Therefore,assessments can be made more accurately.

Research on risk evaluation of mine gas outburst fatalness in Xiangshui Mine

The danger degree evaluation of coal and gas outburst is mainly evaluating spot risk using the safety examination table and the evaluation value can be found.Ac- cording to factors influence coal and gas outburst majorth were qualitative or fuzzy similar factors,used fuzzy gathering classification method for the coal and the gas outburst anal- ysis,established fuzzy model,according to the model adopted the fuzzy similar selective principle proceeding evaluated.Two kinds methods join together analysis can raise on the accuracy rate of the prediction.

Characteristics of gas explosion flow fields in complex pipelines

The explosion flow field in five straight pipes with different diameters and one bending pipe selected from a domestic coal mine are studied by the method of numerical simulation. And the results show that,both in the straight and bending pipes, the pressure wave and velocity wave are accelerated by the rising of reaction rate. As the explosion progressed, with the temperature reaching approximately 3000 K, only one pressure wave and one reaction rate wave were observed, while several velocity waves were found.The larger diameter presented the highest relative pressure as well as the largest velocity increase and subsequent decrease inside the tube. The bent pipes caused both turbulence and kinetic energy to increase, resulting in the acceleration of the reaction rate. The burning time was 7.4% shorter than the burning time observed for the straight pipe. Based on these results, designing one explosion resistance device, and in the practical engineering applications, it was to be proved to meet the security requirements fully.

Simplified Damage Assessment of Slab Against External Blast Load

Recently, the mode approximation method(MAM) has been adopted to analyze beam elements against blast load. However, in real cases, the main structural element of an underground structure is slab and side wall since they not only support the structure itself but also may sustain external loads from blast, earthquake, and other kinds of impact. In the present study, the MAM is extended from beam to plate elements and the soil-structure interaction is considered and simplified when calculating structural response under blast load. Pressure-impulse diagrams are generated accordingly for further quick damage assessment.

Determining Role of the Branched-Chain Reaction Mechanism in Combustion, Explosion and Detonation of Gases

The role of branching-chain mechanism in gas phase combustion is considered. The results of experimental and theoretical investigations show that contrary the accepted for a long time views, branching-chain mechanism of the reaction, competition of chain branching and termination determine the origin and features of gas phase combustion of almost all compounds not only at pressures below atmospheric dozen times, but also at atmospheric and elevated pressures, in conditions of any self-heating. The latter becomes important in the course of developing chain combustion and enhances the chain avalanche. Kinetic methods for controlling combustion, explosion and detonation of gases have been developed by taking into account the decisive role of chain avalanche in these processes. The approach is based on purposeful variation of the rates of the competing reactions of chain branching and termination by means of special small additives. Suggested methods enable not only prevent combustion and explosion, but also adjust the intensity of the process, deflagration to detonation transition and destroy stationary detonation wave at a given distance from the place of its origin.

The Chinese Contemporary Ar Explosion at the Tate in Britain

TEN years ago the notion that Chinese contemporary art could so much as raise a flicker of interest in foreign climes - never mind drive Western cultural pundits into a delirious frenzy - would have been dismissed as pure fancy. At that time Chinese art was assumed to be nothing more than classical calligraphy,

A Method for Calculating Blast Pressure of Failed Lithium-Ion Cells with C-H-O Solvents

Blast pressure of C-H-O solvents on failed lithium-ion cells at the voltage range between 3.8 V and 4.18 V may be calculated by means of the simple semi-empirical equation, y = （Ia ＋ Jb）/（Ka ＋ Lb ＋ Me）, p is the initial density of solvent, Q is the chemical energy of explosion, v is the voltage. The values of a, b, c depend on C-H-O composition. Value of I, J, K, L, Mmay be estimated from the H20-CO2 arbitrary decomposition assumption. Blast pressure derived in this manner can provide preliminary protective estimation and it is compared with experiment results by adiabatic calorimeter.

在突发事件中展示专业素质——访《人民日报》记者吕岩松

当炸弹在距自己不到一米的地方爆炸后,人民日报驻南斯拉夫记者吕岩松奇迹般地抓起了摄影机、采访包和海事卫星电话,然后才冲出房门。这个动作使他成为向国内报告这一重大事件的第一人。6月18日,他就一个战地记者在重大突发性事件的报道中所应体现出的专业素养等问题接受了本刊记者的采访。 记者:你在爆炸发生后,首先抓起了摄影机、采访包和海事卫星电话,而这三样东西是你后来得以顺利完成报道工作,发回大量新闻的关键。

无名英雄——记鸡冠山战斗

1947年7月12日午夜,我人民解放军第三、四纵队对盘踞在铁岭县鸡冠山被我围困之敌王牌军——新六军青年师号称“猛虎师”的二○七师,发起了总攻.经过两昼夜的激烈战斗,扫清了鸡冠山外围之敌,鸡冠山周围的山头主阵地几乎全部拿下.可是天不作美,从总攻的当天晚上开始起连续下了三昼夜的大暴雨.不仅弹药给养运不上来,就连伤员也无法运往后方去了,因此总部被迫作出暂时撤出战斗的决定.这是世上少有的胜利者的撤退.眼看着已到嘴边的肥肉吃不上,同志们心急火燎,有力发挥不出来,急得乱跺脚骂娘.

三五九旅走出的三位“独臂将军”

南泥湾独臂生产 英雄晏福生 晏福生失去右臂,是在红军长征途中的一次战斗中,被敌人飞机扔下的炸弹炸伤后不能保住而被迫截肢的。遵义会议以后,红二方面军为策应一、四方面军会合,决定同敌人进行周旋。晏福生所在的第十六师被赋予担任右路纵队前卫的任务。 由于敌人不断增兵,致使第十六师处于被敌人围堵的困难境地,于是,他们决定突围出去。正当晏福生率部准备突围时,敌人飞机投下了一颗炸弹,落在离他很近的地方爆炸。他一把将战友推倒在地,战友安然无恙,他的右臂却被严重炸伤。由于伤势较重,他自己已经不能突围出去。