Improved Adaptive Genetic Algorithm and Its Application in Short-Term Optimal Operation of Cascade Hydropower Stations

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1 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP mroved Adave Geec Algorhm ad s Alcao Shor-Term Omal Oerao o Cascade Hydroower Saos Jao heg 1 a Yag *2 Ra hou 3 Yoghua Hao 4 Guoshua Lu 5 College o Hydrology ad Waer Resources Hoha Uversy 1 Xkag Road Najg Jagsu rovce Cha 1 zhegjao8826@126.com; 2 kyag@hhu.edu.c; 3 zhour114@163.com; 4 xuayuaxgqg@163.com; 5 guoshua955@126.com Absrac- The mroved Adave Geec Algorhm (AGA) ad s alcao shor-erm jo omal oerao o Qg Rver cascade hydroower saos are reseed hs aer. he mroved mehod a ew seleco oeraor s adoed o kee he dversy o oulao he seleco rocess by makg o-le coverso o ess uco. The resuls o smulave omal oerao based o several rereseave hydrograhs show ha he mroved AGA ca d a more excelle soluo he same algebra. Ad he resuls also show ha ower geerao bee has a cera correlao wh ower geerao amou bu maxmum ower geerao amou s o equal o maxmum ower geerao bee. The research achevemes also have a mora reerece or he comlao o daly geerao schedulg o Qg Rver cascade hydroower saos sysem. eywords- Geec Algorhm; Se Fuco; Seleco Oeraor; TOU Power Prce; Qg Rver Cascade Hydroower Saos. NTRODUCTON As we kow he reveue o hydroower saos ca be mroved by carryg ou omal oerao whou addoal vesme. Ad due o TOU ower rce maxmum ower geerao amou s o equal o maxmum ower geerao bee. So he omal oerao cosderg o TOU ower rce ad amg a maxmzg he ower bee s o raccal value. he case o mehodology or smulao oerao: Dyamc Programmg (DP) heory s already maure bu aces he dmeso dsaser [1 2]. The mroved algorhm abou DP cremeal Dyamc Programmg (DP) Progressve Omzao Algorhm (POA) ec ca overcome he dmeso dsaser a cera degree bu he covergece o algorhm deeds o he covexy o objecve uco [3]. Recely wh he develome o mahemacs ad comuer echology Parcle Swarm Omzao (PSO) A Coloy Algorhm (ACA) Smulao Algorhm (SA) Geec Algorhm (GA) ad oher ew ellge aroaches have bee roosed or omzao oerao [4 5]. geeral radoal algorhms always ace he dmeso dsaser caused by cascade hydroower saos hgh dmeso characersc. Comarg wh radoal algorhms GA has advaages o comug coss. Because has a low requreme o comuer erormace ha s o say GA s more suable or solvg omal oerao o cascade hydroower sysem. A rese GA has bee roosed or omal smulao oerao o hydroower saos. Smle geec algorhm (SGA) based o bary codg was aled o omal oerao o hydroower saos by Guagwe Ma L Wag seekg he omum he ere soluo sace eecvely ad dg he global omal soluo or aroxmae oe ceraly [6]. SGA based o decmal codg was roosed by Dagag Wag Chua Cheg o avod ece search caused by he log srg o bary codg. Ad a resul or a examle showed he ececy o algorhm was advaced [7]. Cosderg he roblems o covergece ad remaury occurred SGA adave geec algorhms (AGA) whch could adjus he arameers adavely accordg o he value o dvdual ess ad dserso degree o oulao was roosed by Shaobo Wag Jachag Je. Ad a resul or a examle dslayed ha AGA has beer sably ad beer erormace o covergece seed [8]. 8 h leraure u orward a mroved aroach abou remaury crossover oerao ad muao oerao. Furhermore he mrovemes o remaury he seleco rocess were already volved he leraures. Sogya hag ook a look a he mac o seleco oeraor o covergece ad comuaoal ececy o geec algorhm ad roosed he corresodg mroveme sraegy each sage o evoluo [9]. The oulao-sored mulroulee wheel seleco wh relaceme (PSMRWSR) was roosed by Che L ad Hogyu Ng advacg he covergece rae o GA eecvely [1]. Quax We Xaeg Lu roosed a ew seleco mehod whch was based o he commucao o dere oulao grous ad could avod rag local covergece by comarg dere seleco mehod he basc GA [11]. Guosheg Hao Yuruo Ya reseed a seleco oeraor based o rgoomerc ucos ug wh roulee wheel seleco or rakg seleco mehod ad a resul or a examle showed hs combed oeraor could d more excelle soluo he laer sage o evoluo [12]. However ew scholars have used hose mrovemes

2 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP omal oerao o hydroower saos. he evoluo he seleco rocess relecs survval o he es ad deermes he eecveess ad covergece seed o he algorhm. Thus Geec algorhm s aeced by he mehod o seleco he whole rocess. Ad hrough mrovg seleco mehod remaure covergece o GA would be avoded well. max m : Bouds or waer level. od : A accuracy corollg arameer. : Pealy coece.. NOMENCLATURES : Balace coeces. : Curre evoluo geerao. T: Maxmum evoluo geerao. Qm Qmax : Bouds or dscharge volume. q: Dscharge volume. N d: Ouu. : low o GHYGB. Q sby Q : Oulow o SBYGHY. A: Ou ower coece. B Q H M : The ole rce mome. : The ower dscharge mome. : The Geerag head mome. : The geerae me mome. : low o GHY ad GB. Q sby Q g hy : Oulow o SBY ad GHY. N : Mmum ouu ha deermed by he requreme o ower ework. s s : dvdual ecodgs beore ad aer he oerao o muao haeg S. : The low o h 1 hydroower sao mome corresodg o Q 1 : The oulow o -1 h hydroower sao mome. a b: Coeces o be obaed va measured daa. B: Sysem arameer whch deermg he deedece degree o radom dsurbace evolvg algebra (T). B B ad B : Peak erod ower rce Normal erod ower rce ad Valley erod ower rce ad g 1 2 ad 3 are he erod corresodg o each rce. s by ad : Power bee o SBY GHY ad GB each erod. g hy F : Power bee o he sysem. Q. V mj Vmj 1: The al ad al sorage o m h hydroower sao he j erod. m j QL m j QS ad mj : The low ower dscharge ad surlus dscharge o mh oe he j erod. mm m Q mm m N mm m ad m max : Dead waer level oerag waer level ad ormal waer level. Q Q mmax ad : Mmum dscharge volume oerag dscharge volume ad maxmum dscharge volume. N N m max ad : Frm ower oerag ower ad salled caacy o m h hydroower sao.. MPROVED ADAPTVE GENETC ALGORTHM

3 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP mroved geec algorhm oers a ew aroach or solvg he smulao. O he oe had he ess requremes o o-egave ca be solved by se-roulee selecve oeraor. O he oher had he arameers ca be adjused adavely accordg o he value o dvdual ess ad dserso degree o oulao. Meawhle els sraegy s used o esure ha he bes dvdual ca o be desroyed each geerao. A. al Poulao ad dvdual Codg The dsrbuo roeres o al oulao aecs covergece erormace o geec algorhm serously ad oor al oulao may resul slow covergece or eve o coverge [13 14]. Cosderg ha hs smulao codg s a dulcao o sgle hydroower sao codg. s very dcul o search a easble soluo by usg radomly geeraed mehod. Thus he soluo sace geerao mehod [15] s aled o geerae easble al oulao hs sudy. Real codg s used o avod ece searchg caused by log srgs o bary code. hs sudy smulao codg s comosed o lked sgle hydroower sao codg ad he waer levels are all lmed he allowable rage. The sgle reservor codg ca be exressed by The waer level ca be deermed rom max m (( ( ) 1) * rd od (1) * m od Besdes he al ad al waer level o sgle hydroower sao should be exressed by m ( ) od ; m e od ( ) (2) (3) B. Fess Fuco Fess uco s cosdered as he objecve uco geec algorhm. Ad omzao oerao o hydroower sao s he cosraed maxmum omzao roblem. The cosras ha have bee ake o accou hs smulao may be classed o 3 ars. The waer level cosras cocludg he al he al he maxmum ad he mmum waer level cosras have bee cosruced hrough desgg code. The waer balace cosra s cosdered as he sae raso equao. Moreover ohers are realzed by ouu ealy ad low ealy he ess uco. The he sgle ess uco ca be rereseed as ( [ ]) ( ) ( * volq ( ) voln ( )) T 1 1 volq( 1 ) voln( 1) where 1 rereses low ealy uco; 1 rereses ouu ealy uco; 1 level ower bee ad ca be calculaed accordg 6 h volq( 1) equao ad 1 s deermed rom q Qm : q Qm volq( 1) q Q max : q Qmax 1 : Qm q Qmax 1 voln ( ) 1 s calculaed accordg 1 N d N : N d N voln ( 1) : N N Fally ess uco o Qg Rver Cascade hydroower sysem s exressed as d ( ) 1 (4) s dvdual F s by (7) C. Geec Oerao 1) Se-Roulee Wheel Seleco Oeraor: Fess uco o dvdual relecs he objecve uco value. Seleco oeraor s he rocess o he es survval basg o calculao o dvdual ess. The roulee wheel seleco oeraors based o rgoomerc ucos are esablshed by roulee wheel selecg combg wh rgoomerc ucos. Ad he sorg mehod seleco oeraors based o rgoomerc ucos are also cosruced by sorg mehod selecg combg wh rgoomerc ucos. Ths sudy chooses roulee wheel seleco oeraor basg o se uco. However ohers ca be smlar used as. (5) (6)

4 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP Where he seleco oeraor s comosed o hree ses as ollows: Se 1. Relace (ess uco) by as ollows m s( ) 2 m a x m (8) Se 2. Calculae cumulave value ad he cumulave rooro o Se 3. Selec cumulave rooro o by a [ 1] uorm radom umber durg each roud o he seleco rocess. Thereore he hgh-ess dvdual s easy o be reaed he seleco rocess because he se uco o hghess dvdual s larger ha he low-ess oe. Trgoomerc seleco oeraors ca esure ha omum ess dvduals would have a hgh robably o beg seleced [13]. Take se seleco or sace x x ad are wo dvduals he same oulao j j s 1 j. m ca be exlaed by s uco s a moooc creasg uco ( 2 m a x m ; j 2 ). Formula (8) shows he seleco oeraor s se by he adaably o dvdual. The ormula does a olear rasormao o ess uco so ha ca solve he roblem ha ess value s egave. Thus hs ew seleco oeraor has more advaages ha radoal oe ad has he raccal value or hydroower sao omal schedulg roblem. order o esure ha he bes dvdual o each geerao s o desroyed hs sudy ados he omal reservao sraegy he rocess o selecg. 2) The Oerao o Crossover: Crossover oerao s a way o orm wo ew dvduals by exchagg some gees o each chromosome. The crossover oerao o cascade hydroower sysem s a mul-o crossover rocess akg a sgle o crossover o each hydroower sao as a u. Ths sudy ados a resrced sgle-o crossover [15] oerao or each hydroower sao. Ad he crossover breako akes lace rd [1-2] (where s he legh o each hydroower sao codg). hs oerao s ake o accou ha he crossover oerao should reserve oo much excelle gees o each dvdual ad roduce ew dvduals eecvely. Moreover he secal ecodg o se al level ad al level cosaly s cosdered. 3) The Oerao o Muao: Muao oerao s a asssa mehod o roduce ew dvduals va gee muao decdg local search caables o geec algorhm. The muao oerao o cascade sysem s a mul-o muao rocess akg a sgle hydroower sao as a u o a sgle muao oerao. Muao has wo aers he oe s uorm muao ad he oher s ouorm muao. Uorm mode goes agas searchg a key area. So hs sudy ados o-uorm muao aer ha s o say usg radom dsurbace o orgal gee. Ad ca be exressed by. s ( smax s) : radom(1) s s ( s sm ) : radom(1) 1 (1 / T )* B ( y) y * (1 r ) (1) 4) Parameer Adave Adjusme: As we kow AGA s sueror o SGA [9]. Thus hs sudy ados he mehod roosed [16] order o mleme arameer adave adjusme sraegy. The crossg robably (P c ) ad muao robably (P m ) are show below. (9) Pc 1 Pc max avg Pc 1 ( Pc1 Pc2)( avg) : avg : avg (11) P m1 ( P P )( ) m1 m2 max Pm 1 : avg P m max avg : avg (12) P P where c1 =.9 c 2 P =.6 m1 =.1 P m 2 =.1. addo he omal reservao sraegy s adoed so ha he bes dvdual o each geerao would o be desroyed he rocess o crossover ad muao

5 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP V. SHORT-TERM JONT OPTMAL SMULATON OPERATON FOR QNG RVER CASCADE HYDROPOWER SYSTEM AMNG AT MAXMUM POWER BENEFT A. Qg Rver Cascade Hydroower Sysem Qg Rver cascade hydroower saos sysem s bul by order o Shubuya hydroower sao (SBY) Geheya hydroower sao (GHY) ad Gaobazhou hydroower sao (GB) rom usream o dowsream. The Ma showg he locao o Qg Rver cascade hydroower sysem Cha s rereseed Fgure 1. Ad he basc ormao o Qg Rver cascade hydroower saos sysem s show Table 1. Fg. 1 Ma showg he locao o Qg Rver cascade hydroower sysem Cha TABLE THE BASC NFORMATON OF QNG RVER CASCADE HYDROPOWER STATONS SYSTEM Dead waer level Normal waer level Frm ower salled caacy SBY 35 m 4 m 31.2*1 4 kw 184*1 4 kw GHY m 2 m 18.7*1 4 kw 121.2*1 4 kw GB 78 m 8 m 6.15*1 4 kw 27*1 4 kw B. he Close Hydraulc Coulg Cosras A equao o lear regresso or dealg wh he calculao o emoral-saal varao o low s esablshed [17] ad s aled jo omzao dsachg o Samexa ad Xaolagd hydroower sao. The equao o lear regresso solves close hydraulc coulg bewee hydroower saos ad mroves he recso o he smulao. ca be rereseed as a * Q b (13) 1 The equao descrbg emoral-saal varao o low rom SBY o GHY va measured daa ca be aroxmaed by Q r (14) sby The correlao coece o hs equao s very close o 1. Thus GHY low may be closely relaed o SBY oulow. By adog he same aroach he correlao equao abou GB low ad GHY oulow ca be aroxmaed by Q r (15) Thus he close hydraulc coulg cosras o Qg Rver cascade hydroower sysem are descrbed well. C. The Objecve Fuco o Omal Smulao Oerao Cosderg TOU Power Prce Esablshg a ece elecrcy marke mechasm whch advacg ower resource allocao ad reducg ework oerag coss has became he key ssues ad a research ocus. Ad he reorm o ower rce s romoed by elecrcy marke reorm. Today wo-ar TOU ower rce s mlemeed Frech segmeed ower rce s used Brsh ad wo sysems elecrcy rce s carred ou Jaa. Meawhle some rovces Cha have begu o ry o ado TOU ole rce. The objecve uco o omal smulao oerao whch amg a maxmum ower geerao bee ca be rereseed as T max B A Q H M 1 Where =1 2 3 T. The eak-valley ower rce has bee ake o accou TOU ower rce ad ower rce has bee dvded o hree ars (Peak erod ower rce Normal erod ower rce ad Valley erod ower rce) accordg (16)

6 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP o dere me. Thus aer ole rce s gve he objecve uco o omal smulao oerao whch cosderg TOU ower rce ca be exressed by 1 2 max( BAQHM BAQHM BAQHM ) g (17) D. Shor-Tme Jo Omal Smulao Oerao or Qg Rver Cascade Hydroower Sysem Amg a Maxmum Power Bee Accordg o Cha s ower ormao he ole TOU ower rce Hube Provce s show Table 2. TABLE THE ONLNE TOU PRCE OF QNG RVER CASCADE HYDROPOWER SYSTEM Perod(h) -8 he ole rce(yua/kw.h) Accordg o Table 2: h~8 h rereses Valley erod 1 h~12 h ad 18 h~22 h rerese Peak erod ohers rerese Normal erod. Thus B =.44 yua/kw.h B =.39 yua/kw.h ad B g =.35 yua/kw.h 6 h equao. The objecve uco o Qg Rver cascade hydroower sysem s esablshed o ursue maxmum ower bee. Ad he schedule erod (T) s oe day dvdg o 24 hour. Thus he u o schedule s 1 h ad he smulao ca be rereseed as The objecve uco: Subjec o he ollowg cosras: Waer balace equao: F s by (18) V mj 1 V mj ( mj QL mj QS ) m j mj (19) Waer level cosras: Dscharge cosras: Ouu cosras: Coulg cosras: m m m m max Q Q Q mm m mmax N N N mm m m max (2) (21) (22) Q sby 1.257Q Accordg o he smulao arragg ower dsrbuo based o waer he al ad al waer level o SBY GHY ad GB are assumed as 4 m 2 m ad 8 m. waer balace equao he low o SBY s asceraed he low o GHY ca be obaed by he oulow o SBY 3 h equao he low o GB ca also be obaed by he oulow o GHY 4 h equao. V. THE SMULATON OPERATON FOR REPRESENTATVE HYDROGRAPHS Abou he smulao hree rereseave hydrograhs are adoed or smulae omal oeraos order o maes he raoaly o resuls. The rs codo rereses ha a large hydrograh occurs cascade sysem he secod codo rereses a mddle hydrograh occurs cascade sysem he hrd codo rereses a small hydrograh occurs cascade (23) (24)

7 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP sysem. Cosderg GA s a omzao mehod mag bologcal evoluo based o sochasc heory hs aer sudes 1 smulao oeraos or each hydrograh ad selecs he bes oe as he omal schedulg resul. Besdes he oulao sze (o) o geec algorhm s 6 ad evoluoary geerao (ge) s 2. Some smulao resuls abou he coras bewee radoal roulee wheel seleco oeraor ad Se-roulee wheel seleco are summarzed Table 3. The comarso resuls o dsrbuo o sysem ower geerao amou ad sysem ower geerao bee rs codo are gve Fgures 2-3; he comarso resuls secod codo are descrbed Fgures 4-5 ad he comarso resuls hrd codo are rereseed Fgures 6-7. TABLE THE CONTRAST SMULATON RESULT BETWEEN TRADTONAL ROULETTE WHEEL SELECTON OPERATOR AND SNE-ROULETTE WHEEL SELECTON. (MLLON YUAN) Frs Codo Secod Codo Thrd Codo Tradoal Se-roulee creasg Noes:o=6ge=2. Power geerao amou Power geera bee Power geerao amou (1kw.h) Sages Power geera bee (1 housad yua) Sages Fg. 2-3 Dsrbuo o sysem ower geerao amou ad sysem ower geerao bee rs codo. Power geerao amou (1 kw.h) Power geerao amou Sages Power geerao bee (1 housad yua) Power geerao bee Sages Fg. 4-5 Dsrbuo o sysem ower geerao amou ad sysem ower geerao bee secod codo 25 Power geerao amou Power geera bee 14 Power geerao amou (1 kw.h) Sages Power geera bee (1 housad yua) Sages Fg. 6-7 Dsrbuo o sysem ower geerao amou ad sysem ower geerao bee hrd codo he case o solvg he omal oerao o hydroower sysem as [12] rooses s easy o d he global omal soluo he laer sage o evoluo by adog rgoomerc seleco oeraors. From Table 3 AGA based o Seroulee wheel seleco has a beer erormace o covergece seed he global omum resul wheher he low s bg or small wh he same geeraos. The ew seleco oeraor ca avod elmag dulcao dvdual ha s o say ca crease covergece rae o algorhm by maag he oulao dversy. cocluso hs ew seleco oeraor s raccal or omal oerao o hydroower sysem. Fgures 1~6 rerese: ower geerao bee has a cera correlao wh ower geerao amou bu maxmum ower geerao amou s o equal o maxmum ower geerao bee. Ths s maly because o TOU ower rce ha s o say due o chages he rce o elecrcy. Thereore uder he TOU ower rce evrome maxmum ower geerao bee has more raccal value ha maxmum ower geerao amou as objecve uco o hydroower

8 Commucaos ormao Scece ad Maageme Egeerg Mar. 213 Vol. 3 ss. 3 PP sysem omal schedulg. V. CONCLUSON AND FUTURE WOR The reveue o hydroower sysem ca be romoed by carryg ou omal oerao whou addoal vesme. Whle due o he exsece o TOU ower rce maxmum ower geerao amou does o equal maxmum ower geerao bee. So he omal oerao whch cosderg TOU ower rce ad amg a maxmzg he ower bee s raccal. The correlao bewee ower geeraos bee ad ower geerao amou uder TOU ower rce evrome eeds o be urher suded he ex erod. Abou he esablshme ad soluo mehodology o omzao schedulg smulao: o oe had esablshg a lear regresso equao o he dscharge ( erms o usream hydroower sao) ad he low ( erms o dowsream hydroower sao) s a ew mehod o rerese he close hydraulc coulg cosra bewee hydroower saos. Bu hs sudy does o cosder he close hydraulc coulg cosra a he las me he schedule erod. Thus hs wll be ake o accou he uure. O he oher had whe he ess s o-egave he Se-roulee wheel seleco oeraor ca solve he roblem ha radoal roulee wheel seleco oeraor ca o dsose o. ca crease covergece rae o GA by maag he oulao dversy ha s o say hs ew seleco oeraor could be reerece meag or omal oerao o hydroower sysem. ACNOWLEDGMENT The achevemes are uded by Naoal Scece Suor Pla Projec o Cha (29BAC56B3) ad he Prory Academc Program Develome o Jagsu Hgher Educao suos (PAPD). REFERENCES [1] J-Shy Yag Na-mg Che. Shor erm Hydrohermal Coordao Usg Mul-Pass Programmg. EEE rasacos o ower sysems vol. 4 No [2] Sh-Chug Chag Chu-Hug Che -og Fog ad P. B. Luh. Hydroelecrc Geerao Schedulg wh a Eecve Dereal Dyamc Programmg Algorhm. EEE rasacos o ower sysems vol. 5 No [3] Tao Wag. Theory Mehod ad Alcao o Reservor Omal Corol. Najg: Hoha Uversy 29. [4] H.. Ya P. B. Luh X. H. Gua. Schedule o Hydrohermal Power Sysem. EEE rasacos o ower sysems vol. 8 No [5] A. Arce T. Ohsh ad S. Soares. Omal Dsach o Geerag Us o he au Hydroelecrc Pla. EEE rasacos o ower sysems vol. 17 No [6] Guagwe Ma L Wag. Alcao o Geec Algorhm o Omal Oerao o Hydroower Sao. Advaces Waer Scece vol. 8 No [7] Dagag Wag Chua Cheg Mg L. Sudy o he omal oerao o hydroower sao based o geec algorhms. Joural o Norh Cha sue o Waer Coservacy ad Hydroelecrc P ower vol. 22 No [8] Shaobo Wag Jachag Je e og. Alcao o adave geec algorhm omzao o reservor oerao. Joural o Hydraulc Egeerg vol. 4 No [9] Sogya hag. Oeraor Seleco ad Comuaoal Ececy Aalyss o Geec Algorhm. Joural o Ngbo Uversy (NSEE) vol. 22 No [1] Che L Hogyu Ng. mroved seleco oeraor o geec algorhm. Joural o Taj Uversy o Techology 28 vol.24 No [11] Quax We Xaeg Lu Qa Huag e al. The comarso o dere seleco mehods geec algorhms. Joural o Commucao Comuer vol. 5 No [12] Guosheg Hao Yuruo Ya Yogqg Huag e al. Trgoomerc Selecve Oeraors Geec Algorhm. Joural o Jaga Uversy vol. 9 No. 2): [13] alzala A M Flemg P J. Geec Algorhms Egeerg Sysem. Lodo: The suo o Elecrcal Egeers [14] B Wu Ja Wu Xuya Tu. Research o Fas Geec Algorhm. Joural o UEST o Cha vol. 28 No [15] Xaog Wag Lmg Cao. Geec Algorhms: Theory alcao ad mlemeao. X a: Press o Xa Jaoog Uversy 22. [16] a Yag Yubo Lu. Sysem Decomoso-Coordao Macro-Decso Mehod or Reservors Based o Mul-Objecve Aalyss. Advaces Waer Scece vol. 12 No