Open Access Researching Coal and Rock Character Recognition Based on Wavelet Packet Frequency Band Energy

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1 Sed Orders for Reprits to The Ope Automatio ad Cotrol Systems Joural, 04, 6, Ope Access Researchig Coal ad Roc Character Recogitio Based o Wavelet Pacet Frequecy Bad Eergy Guaghui Xue *, Xiyig Zhao, Ermeg Liu, Weijia Dig, ad Baohua Hu School of Mechaical, Electroic ad Iformatio Egieerig, Chia Uiversity of Miig ad Techology (Beijig), Beijig 00083, Chia Abstract: At preset top coal cavig is doe by worers at the fully mechaized top-coal cavig face, where the productio rate is low ad the worers safety is uder threat. I order to reduce the casualties, realize less people eve o people ad the high-efficiet ad high-yield of coal mie, the coal ad roc character recogitio was researched o udergroud, the method based o the wavelet pacet frequecy bad eergy aalysis, for coal ad roc idetificatio was proposed. Usig the self-developed mie portable vibratio data recorder to pic up the vibratio sigals at the hydraulic support tail beam uder the differet coditios of coal cavig, gague cavig ad roof roc cavig i the fully mechaized top-coal cavig face. The coclusio has bee draw after aalyzig the vibratio sigals by the wavelet pacet frequecy bad eergy: Whe coal cavig, the Edge bad focus o 50 Hz~56.5 Hz ad 87.5 Hz~500 Hz, whe gague cavig, the Edge bad focus o 0~65 Hz ad 937.5~50 Hz, whe roof roc cavig, the Edge bad focus o 875~87.5 Hz ad 3750~406.5 Hz. The result shows that differet edge bads uder the differet coditios ca be used as the criterio for the coal ad roc character recogitio i the fully mechaized top-coal cavig face. Ad research results could provide a ew idea ad the method for the coal ad roc character recogitio. Keywords: Coal ad roc characters recogitio, fully mechaized top-coal cavig face, vibratio sigals, wavelet pacet frequecy bad eergy.. INTRODUCTION The fully mechaized top-coal cavig face has bee widely applied i thic coal seam miig i Chia, ad is used as oe of the mai methods of thic coal seam miig [, ] for high yield ad high efficiecy, low cosumptio, safety ad good ecoomic beefits. At preset, the close timig of coal export durig the top coal cavig are judged by the worer's ituitio ad experiece based o whether there are gague ad i how much quatity i the coal (coal ad roc characters). Due to harsh eviromet, dust, ad daress, it is difficult for worers to judge the coal ad roc characters that ievitably cause their "less fall" ad "over fall" status. Less fall ot oly leads to the low coal recovery rate, but also icreases the ris of goaf spotaeous combustio. Over fall would result i coal quality declie, ivalid trasport, icreased washed coal cost ad reder coal mie worers' health ad persoal safety uder serious threat. This study ivolves: usig the self-developed YHJ(C) mie portable vibratio recorder to pic-up the vibratio respose sigal at the hydraulic support tail beam excited by coal, gague ad roof roc cavig; usig the method of the wavelet pacet frequecy bad eergy to aalyze those data; ad fidig the differece uder those coditios. *Address correspodece to this author at School of Mechaical, Electroic ad Iformatio Egieerig, Chia Uiversity of Miig ad Techology (Beijig), Beijig 00083, Chia; Tel: ; xgh@cumtb.edu.c. WAVELET PACKET FREQUENCY BAND EN- ERGY.. Wavelet Decompositio Wavelet decompositio [3, 4] is a time-frequecy localizatio aalyzig method to realize time ad frequecy chage at the same time. + ψ Satisfied allow coditios: () tdt= 0 () ψ () t is mother wavelet fuctio. By flexig ad traslatig ψ () t, get t b ψ ab, () t = a ψ( ) () a a reflects the scale fuctio, b shows traslatioal positio at t axis, ψ a, bt () is the wavelet fuctio. I practical applicatio, sigal ad parameter a, b i wavelet fuctio are discrete variable. Settig a = m, b = m, we ca get m, () ψ m ( ),(, ) ψ t t m Z m = (3) ψ m, () t is wavelet fuctio geerated biary discrete wavelet /4 04 Betham Ope

2 794 The Ope Automatio ad Cotrol Systems Joural, 04, Volume 6 Xue et al. Fig. (). The YHJ(C) mie portable vibratio recorder. If biary discrete wavelet! m, (t) satisfies the coditio of orthoormal basis of ormed liear space L (R), ad the biary orthogoal scalig fuctio is geerated by mother wavelet fuctio! (t), get! m, (t) = " m!( " m t " ) ( m,!z ) (4) ψ m, () t s wavelet space W ad! (t) s scale space V m m, m are complemetatio i the L (R) s space. Scale space V m! is the straight sum of V m ad W m. So x(t) s orthogoal wavelet decompositio is N m N x(t) = "" d # m, (t) + " c $ N, (t) (5) m=!z!z N is the exploded layer umber, d m is wavelet coefficiets, c N is scale coefficiets at the N layer.! N, (t) is biary orthogoal scalig fuctio whe m= N... Wavelet Pacet Decompositio Wavelet decompositio oly decomposes the low frequecy part ad gives up decomposig of the high frequecy part. But wavelet pacet decompositio [5] mae up for the shortage. Assumig that ϕ ( x) ad ψ ( x) are oe of V0 ad W 0 orthoormal basis respectively. Because V 0!V " ad W0 V, ϕ ( x) ad ψ ( x) belog to the space of V, amely ϕ( x) ψ ( x) are liear ufolded by orthogoal basis ϕ, ( x ) i the space of V :!(x) = " h 0 ()!(x # ) (6)! (x) = " g()#(x $ ) (7) Amog them, h0( ) = ϕϕ,,, g ( ) = ψϕ,,. Assumig u 0 () x = ϕ () x, u () x = ψ () x two dimesio equatio ca be writte: u (x) =! h()u (x " ) (8) u! (x) = " g()u (x! ) (9) u is orthogoal wavelet pacet of pacet orthogoal scalig fuctio ϕ ( x)..3. Frequecy Bad Eergy Aalysis. Sum of the eergy of each bad sigal: E j =! X (t) (0) = E j represets the wavelet pacet eergy at last j layer, X represets spectrum coefficiet of discrete poits after beig decomposed by layer wavelet pacet. Use the total eergy E0 = E j! i= to ormalize the eergy sigal feature vector E [ E E E E E ] =,, 3, 4, get E ' = "# E, E, E 3, E 4!!! E $ % () The above mae the theoretical foudatio of frequecy bad eergy of wavelet pacet aalysis. 3. ACQUIRE THE COAL AND ROCK S VIBRATION SIGNAL 3.. Mie Portable Vibratio Recorder ad Test YHJ(C) mie portable vibratio recorder [6, 7], as show i Fig. (), is the self-developed 4 chael coal mie vibra-

Researchig Coal ad Roc Character Recogitio The Ope Automatio ad Cotrol Systems Joural, 04, Volume 6 795 -poit at bac beam; - coal wiig machie; 3- hydraulic support; 4- frot scraper coveyor; 5-Rear

3 Researchig Coal ad Roc Character Recogitio The Ope Automatio ad Cotrol Systems Joural, 04, Volume poit at bac beam; - coal wiig machie; 3- hydraulic support; 4- frot scraper coveyor; 5-Rear scraper coveyor. Fig. (). Site equipmet layout ad measurig poit locatio. tio sigal acquisitio istrumet. Its samplig frequecy is 0~50 Hz, ad ca collect, record ad store the mie equipmet vibratio sigal data, ad provide techical support ad guidace for the daily maiteace ad repair of the equipmet. Site equipmet layout ad observatio poits. This test was carried out at 9 fully mechaized top-coal cavig face of Dogpo coal mie i Shaxi provice. The vibratio data was collected at the hydraulic support tail beam uder the coal cavig, gague cavig ad roof roc cavig coditios. Samplig frequecy was 0 Hz. The poit at 43# hydraulic support was selected after field ivestigatio ad commuicatio with worers. Fig. () shows arragemet of measuremet poits, ad # poit collected the vibratio data at the hydraulic support beam ormal directio. Fig. (3) is the time domai waveform figure uder various wor coditios. (a) coal cavig (b) gague cavig (c) roof roc cavig Fig. (3). The time history of vibratio sigal at the measuremet poit of the hydraulic support tail beam uder various wor coditios. Results ca be obtaied from Fig. (3). The vibratio amplitude is about 3 g geerated uder the coditio of coal cavig. No obvious pheomeo of impact The vibratio amplitude is about 8 g geerated uder the coditio of gague cavig. Obvious pheomeo of impact The vibratio amplitude is about 5g geerated uder the coditio of roof roc cavig. Obvious pheomeo of impact 3.. Frequecy Bad Eergy of Wavelet Pacet Aalysis. Based o the regularity comparability of wavelet coefficiet, choose the db wavelet pacet basis, ad 4 layer of wavelet pacet to aalyse the vibratio sigals. 0~5000 Hz have bee decomposed to 6 bads, ad gettig the time - frequecy diagram, as show i Fig. (4). Calculate the eergy of each bad uder various wor coditios, ad the eergy histograms have bee gotte as ormalized, as show i Fig. (5). From Fig. (5) coclusios ca be draw: Whe coal cavig, the eergy betwee A5 bad ad A8 bad, amely 50 Hz~56.5 Hz ad 87.5 Hz~500 Hz is higher tha i other coditios.

4 796 The Ope Automatio ad Cotrol Systems Joural, 04, Volume 6 Xue et al. (a) coal cavig (b) gague cavig (c) roof roc cavig Fig. (4). Wavelet pacet decompositio of vibratio sigals uder various wor coditios. Whe gague cavig, the eergy amog A bad, A bad ad A4 bad, amely 0 Hz~65 Hz ad 37.5 Hz~50 Hz is higher tha i other coditios. Whe roof roc cavig, the eergy betwee A7 bad ad A3 bad, amely 875 Hz ~87.5 Hz ad 3750 Hz ~406.5 Hz is higher tha i other coditios. 4. DISCUSSING THE DATA ANALYSIS RE- SULTS The results foud i this paper are uiversal for differet coal mies ad differet worig faces. But the specific frequecy bad threshold uder various coditios applies oly to this test of worig face. For other fully-mechaized cav-

5 Researchig Coal ad Roc Character Recogitio The Ope Automatio ad Cotrol Systems Joural, 04, Volume of oliear ad o-statioary ito bads, calculate the eergy of each bad to fid the differece. It ca be the powerful tool of coal ad roc recogitio at fully mechaized topcoal cavig face. CONFLICT OF INTEREST The authors cofirm that this article cotet has o coflict of iterest. Fig. (5). The frequecy bad ormalized eergy histograms of vibratio sigal at the measuremet poit of the hydraulic support tail beam uder various wor coditios. ig face, the method proposed i this paper alog with test ad aalysis ca be used to esure the threshold uder the various coditios. Cocrete judgmet of coal ad roc character recogitio ca bee doe. 5. SUMMARY The amplitude at the time domai waveform figure is differet at the measuremet poit of the hydraulic support tail beam uder various wor coditios. The amplitude is about 3 g whe coal cavig, 9 g whe gague cavig ad 5 g whe roof roc cavig. The wavelet pacet frequecy bad eergy aalysis has show the followig: the edge bad cocetrate o 50 Hz~56.5 Hz ad 87.5 Hz~500 Hz whe coal cavig, 0 Hz~65 Hz Hz ~50 Hz whe gague cavig, 875 Hz~87.5 Hz ad 3750 Hz ~406.5 Hz whe roof roc cavig. The edge bad is differet obviously, ad it ca be the gist of coal ad roc character recogitio uder various worig coditios. The method of the wavelet pacet frequecy bad eergy aalysis ca decompose the coal ad roc s vibratio sigal ACKNOWLEDGEMENTS This wor was supported by the Natioal Key Basic Research ad Developmet Project (No.04CB046300), ad Fudametal Research Fuds for the Cetral Uiversities (No.009QJ6). REFERENCES [] J. M. Li, ad Z. Y. Zhag, The fully mechaized top coal cavig miig techology i complicated seam of Kailua miig area, Joural of Chia Coal Society, vol., pp , 00. [] Z. J. Wag, ad Z. W. Zhag, Miig techology of 300 m log fully-mechaized top coal cavig miig face with aual productio of over 0 millios tos, Joural of Chia Coal Society, vol. 3, pp. 3-35, 04. [3] L. Zhou, X. Xia, Y. J. Wa, H. Zhag, ad P. Lei, Harmoic detectio based o wavelet trasform, Trasactios of Chia Electrotechical Society, vol. 9, pp , 006. [4] Z.L. Liu, Evaluatio o developig level of uba agglomeratio derived from resources exploratio, Joural of Applied Scieces, vol. 3, o., pp , 03. [5] F. T. Wag, X. J. Ma, ad Y. Zou, Local power feature extractio method of frequecy bads based o wavelet pacet decompositio, Trasactios of the Chiese Society for Agricultural Machiery, vol. 5, pp [6] J. J. Yag, G. H. Xue, G. R. Zhao, S. Y. Wu, ad M. Wu, Research ad developmet o mie itrisic safe mode vibratio sesor, Coal Sciece ad Techology, vol., pp. 7-74, 03. [7] G. H. Xue, M. Wu, ad B. Zhou, Developmet of mie portable digital recorder, Coal Sciece ad Techology, vol. 5, pp. 5-54, 004. Received: September 6, 04 Revised: December 3, 04 Accepted: December 3, 04 Xue et al.; Licesee Betham Ope. This is a ope access article licesed uder the terms of the Creative Commos Attributio No-Commercial Licese ( which permits urestricted, o-commercial use, distributio ad reproductio i ay medium, provided the wor is properly cited.

Radar emitter recognition method based on AdaBoost and decision tree Tang Xiaojing1, a, Chen Weigao1 and Zhu Weigang1 1

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