The research on modeling of coal supply chain based on objectoriented Petri net and optimization

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1 Proceda Earth and Planetary Scence 1 (2009) Proceda Earth and Planetary Scence The 6 th Internatonal Conference on Mnng Scence & Technology The research on modelng of coal supply chan based on obectorented Petr net and optmzaton Lu Man-zh a, Zhou Me-hua a, Lv Xue-qng a, Yang J-xan b, * a School of Management, Chna Unversty of Mnng & Technology, Xuzhou , Chna b Department of Envronmental Protecton and Energy-savng, Yankuang Group Co. Ltd, Zoucheng , Chna Abstract Obect-orented Petr Net modelng of coal supply chan system can be establshed from the perspectve of workflow by applyng the technology of obect-orentaton and Petr net. On the bass of the modelng, proft maxmzaton optmzaton for the selecton of resources and the envronment n a certan condton to meet customer demand s taken as the coal supply chan optmzaton obectve. And under the quanttatve descrpton and analyss of the nternal nodes, logstcs, captal flow and nformaton flow n coal supply chan system, the optmal method s used for obectve optmzaton. Through ths research, we have learned that the use of the method n coal supply chan modelng and obectve optmzaton can accurately reflect the operaton of the coal supply chan and ts resource constrants, whch wll fnally mprove decson-makng performance. The complex systems can be hghly abstracted by usng ths OPN model whch s also easy for expanson and optmzaton model has a strong versatlty. Keywords: obect -orented Petr net ; coal supply chan; modelng; optmzaton 1. Introducton Wth an ncreasngly compettve coal market, more and more customer demands, the coal supply chan operaton and management s becomng ncreasngly complex and mportant. Characterstcs of the new type of supply chan such as parallel, asynchronous producton, redundancy of equpment functons can solve the dverse needs of the processng path, but at the same tme create hgher ncdence of resources conflct and ncrease the dffculty of the supply chan schedulng and coordnaton, such as nablty for the supply chan schedulng system to be carred out n accordance wth the orgnal plan [1], and ncreased complexty of the system analyss study. Coal supply chan also has these problems. Therefore, establshng a common, easy to expand coal supply chan model and optmzng the coal supply chan operaton are the keys to coal supply chan plannng and schedulng studes. In recent years, many scholars studes on the coal supply chan were focused on the coal supply chan workflow descrpton[2], the * Correspondng author. Tel.: E-mal address: lumanzh@126.com Publshed by Elsever B.V. do: /.proeps Open access under CC BY-NC-ND lcense.

2 L. Man-zh et al. / Proceda Earth and Planetary Scence 1 (2009) coal supply chan structure[3], the coal supply chan unon[4], the coal supply chan characterstcs[5] etc. However, the coal supply chan modelng method and how to realze the coal supply chan optmzng operaton accordng to the changes of customer demand and the nternal and external envronmental condtons etc are lack of n-depth study. Petr net technology provdes a possble method for descrbng and analyzng the structure of the supply chan, whch demonstrates unque advantages such as easly expressng prorty orders of supply chan actvtes, batch process and asynchronous concurrent programmng [6]. Petr net-based supply chan modelng method can well descrbe logstcs, nformaton flow and captal flow of the supply chan. Applcaton of Petr nets to the supply chan busness process smulaton, modelng and dynamc analyss has attracted researchers both at home and abroad, and a great deal of research results have come exstence[7]. However, because the basc Petr net mo del s very complex[8], expandng hgh-level Petr nets are generally used to descrbe the system, whch are colored Petr net[9], tme Petr nets[10] and so on. But because they are non-modular desgn, they have poor mantanablty and lack of reusablty. And there are exstences of the closed system wthout nput and output and the "exploson" of the state space and so on [11]. It s the obect-orented technology beng ntegrated nto the Petr net that s Obectorented Petr Net that can enhance the characterstcs of Petr net model such as the modularty and easy expanson and reusable, and can effectvely resolve the ssues such as state space exploson. So Obect-orented Petr Net s more applcable to the modelng of complex systems [12]. Because supply chan processes need to consder each of the partcpatng obects [13], Obect-orented Petr Net (OPN) s appled to carry on the coal supply chan operaton flow modelng n ths paper. Frstly, from the perspectve of workflow, obect-orented Petr Net approach s used to establsh the coal supply chan model, to acheve a hgh degree of abstracton of coal supply chan and scalablty of the model by establshng the good system nterface. On the bass, the nternal nodes, logstcs flow and captal flow n coal supply chan system are descrbed and analyzed by the mathematcal language. And the mult-obectves of coal supply chan system optmzaton are converted nto the sngle-obectve of proft maxmzaton n coal supply chan optmzaton for the selecton of resources and the envronment n a certan condton to meet customer demand, and the optmal method s used for obectve optmzaton of coal supply chan operaton, so as to provde the decson supports for coal supply chan plannng and operaton schedulng. 2. OPN model of coal supply chan system 2.1. OPN To model the coal supply chan system (recorded as S), S (system s OPN) wll be looked as a bnary group n ths paper, and be defned as S = { O, R}. Here: O for the set of obects n the system; R for the set of obect relatons n the system; obect O and relatons R are defned respectvely. O = { O, = 1,2, L, I, I N} O = { P, T, IM, OM, I, O, C} Of whch: P as the set of places of obect O ; T as the set of transtons of obect O ; IM as the set of nput nformaton places of obect O ; OM as the set of output nformaton places of obect O ; MP =IM OM : I as nput mappng, I (P,T) as the nput functon of from the place P to transton T ; O as output mappng, O (P,T) as the output functon of from the place T to transton P; C as the color set of places(doors). R = { R,. = 1,2, L, I,, I N } R = { OM, G, IM, COM ( ), CIM ( ), CG ( ), I, O } Of whch: OM -lmted set of output nformaton places of obect O ; IM -lmted set of nput nformaton places of obect O ; G lmted set of doors of nformaton delvery from O O ; C(OM ) color set of output nformaton places of obect O ; C(IM ) color set of nput nformaton places of obect O ; C(G ) color set of G ; I (OM,G ) as the nput functon of from the output nformaton place OM to door G ; O (IM,G ) as the output functon of from the door G to nput nformaton place OM. The nternal behavor and actvtes changes of physcal obect O of OPN model are descrbed by places and transtons. The queue of descrbng specfc actvtes methods s decded by I and O, whch lmt the nput / output relatonshps between P,T and MP of obect O. G wll be lghted a fre when a nformaton place has a token or

3 1610 L. Man-zh et al. / Proceda Earth and Planetary Scence 1 (2009) control rules are desgnated by external. The condtons of nformaton place MP acceptng a message are that a nformaton place MP has a token and G can be lghted a fre Coal supply chan OPN model establshment Obect establshment Coal supply chan operaton process s the process n whch coal enterprses and coal supply chan partners produce and delver the coal products to meet the users requrements by the use of the nformaton of market and customer demands [14]. In other words, the framework of coal supply chan s that upstream supplers (such as mechancal, electrcal, tmber enterprses, etc.) are as the raw materals supplers of coal enterprses, whle the mnng groups (ncludng raw coal mnng, raw coal transportaton, coal sales, etc.) are as the raw coal and refned coal producers, and coal products are transported to the users through transport lnks. The framework of coal supply chan ncludes the nput-output relatons of the logstcs as the man lne, nformaton flow and captal flow [15]. Thus the obects of coal supply chan system are acheved by dvs on from the perspectve of partcpatng subects. The ntegral coal supply chan system ncludes the man obects whch are upstream supplers (such as mechancal, electrcal, outsourcng coal provders etc), coal enterprses (nternal supply chan processes nvolvng raw coal mnng, raw coal transportaton, coal processng, marketng etc), logstcs servce provders (such as coal transport logstcs servces provders of ralways, hghways and other sectors), coal customers Desgn of obect OPN model The overall analyss of coal supply chan system modelng should be done to buld the basc attrbutes of the each obect. For example, OPN model of coal enterprse s shown n fgure 1. IM1 IM2 P1 T1 P2 T2 P3 T3 P4 T4 OM4 IM3 T9 P8 T10 IM4 T8 P7 T7 T6 P6 T5 P5 OM1 OM3 Fg. 1. OPN model of coal enterprse Table 1. The meanngs of places and transtons n the OPN model of coal enterprse Letter Meanng Letter Meanng P1 Producton equpment avalable T6 Coal blendng fnshed P2 Raw coal producton T7 Sales request P3 Washng processng sector free T8 Sales fnshed P4 Wash ng processng T9 Outsourcng coal request P5 Coal blendng sector free T10 Outsourcng coal fnshed

4 L. Man-zh et al. / Proceda Earth and Planetary Scence 1 (2009) P6 Coal blendng IM1 Informaton of the outsde customer needs P7 sale IM2 Raw coal savng and mnng condtons nformaton P8 Purchasng coal IM3 The nformaton of coal companes agreeng to supplers goods supply T1 Coal producton request IM4 The nformaton of coal companes agreeng to co-operate logstcs servces T2 Completon of the mass producton OM1 The coal enterprse sends out the purchase nformaton T3 Washng coal request Inform coal transport logstcs servce provder to transport the coal nformaton T4 Washng process fnshed OM3 Informs the customer payment nformaton T5 Coal blendng request OM4 Raw coal savng and mnng condtons changng nformaton Coal supply chan system OPN desgn System s OPN desgn s essentally the ntegraton of varous obects OPN and obect-relatonal networks, That s, the nternal structure of each obect OPN would be packaged, only the nterface part could be left, that s to say, the places of the nput and output relatonshp between ths and other obects OPN are left as the nterfaces. Accordng to each obect OPN and relatonshp nets between the obects, the coal supply chan systems ntegraton model are set up, as shown n fgure 2. The meanngs of the places and doors of the model are shown n table 2, the resource places and transtons of the other partcpatng obects OPN are no longer lsted because of the paper length. IM11 IM12 O1 OM1 1 G6 G1 IM21 IM22 O2 IM23 IM G2 G4 IM31 O3 OM3 1 G3 G7 G5 OM4 1 OM4 2 O4 IM41 Fg.2 OPN model of coal supply chan system Table 2. Desgnatons of OPN message and gates Obect Informaton place O1 O2 O3 O4 IM11 IM11 OM11 IM21 IM22 IM23 IM24 Coal customer Coal enterprse Coal suppler Logstcs servce provder Coal customers receve the coal product whch are delvered by the logstcs servce provder Coal enterprse meet the needs of coal customers Coal customers new demands nformaton request Informaton of the outsde customer needs Raw coal savng and mn ng condtons nformaton The nformaton of coal companes agreeng to supplers goods supply The nformaton of coal companes agreeng to co-operate logstcs servces

5 1612 L. Man-zh et al. / Proceda Earth and Planetary Scence 1 (2009) Gate IM31 OM31 IM41 OM41 OM42 G1 G2 G3 G4 G5 G6 G7 The coal enterprse sends out the purchase nformaton Inform coal transport logstcs servce provder to transport the coal nformaton Informs the customer payment nformaton Raw coal savng and mnng condtons changng nformaton Coal supplers receve the coal purchase nformat on of coal enterprses Coal supplers reply coal enterprses purchasng coal Logstcs servce provders receve the nformaton of coal enterprses seekng coal transport Logstcs servce provders reply coal enterprses seekng coal transport Logstcs servce provders delver coal commodtes to coal customers Coal customers demand nformaton network transmtted to coal enterprses Coal enterprses seekng for coal supplers Coal enterprses evaluatng coal products supplers Coal enterprses seekng for coal logstcs servce provders Coal enterprses evaluatng logstcs servce provders Coal enterprses sellng Logstcs servce provders transport ng coal products to customers 3. Optmzaton of coal supply chan system 3.1. Optmzng goals and deas of the coal supply chan system Based on the coal supply chan system OPN model bult from the perspectve of work flow, the coal supply chan optmzaton s studed n ths part. To optmze the supply chan system, mnmze the cost or maxmze the proft s usually looked as the goal of supply chan desgn. But wth the change of the market envronment, enterprses are tryng to move away from makng every transacton gan maxmze profts to establshng mutually benefcal relatons between enterprse and customers or the other nodes (such as supplers) n the supply chan[16]. For example, coal supply chan s mpossble to satsfy all customer needs, so on the condton of lmted resources, coal enterprses should focus on buldng a good relatonshp wth the mportant and hgh-value customers, and gve an expresson on ther nterests n the supply chan dynamc optmzaton process. Therefore, n ths paper the coal supply chan optmzaton s consdered as a mult-obectve optmzaton, whch has the goals of customer satsfacton and coal supply chan proft maxmzaton. In ths paper, the basc procedure of the coal supply chan optmzaton s: frst of all, the mportance of customer should be evaluated by use of fuzzy comprehensve evaluaton method, then mult-obectve on the part of customers would act as the constrant condtons n the supply chan of mult-obectve optmzaton, the smple of and the mathematcal model of practcal coal supply chan optmzaton would be establshed by use of lnear programmng, that s to say, the mult-obectves of coal supply chan system optmzaton are converted nto the sngle-obectve of proft maxmzaton n coal supply chan optmzaton for the selecton of resources and the envronment n a certan condton to meet customer demand, and the optmal method s used for obectve optmzaton of coal supply chan operaton. The model has two prncples: coal supply chan optmzaton s a dynamc mult-obectve optmzaton; t s prorty to ensure the supply of coal to maor customers [17] Quanttatve descrpton and analyss of process node and a varety of flow n coal supply chan The mplementaton dffculty of coal supply chan based on the even does not le n the choce of the structure of enttes, but ts emphass s optmzng the supply chan process [18]. The three-ter supply chan optmzaton that nvolvng coal enterprses (the nternal supply chan also ncludng raw coal mnng factores, coal washng plants, sales departments and other nodes), the outsourcng coal supplers and customers s studed n ths paper. The

6 L. Man-zh et al. / Proceda Earth and Planetary Scence 1 (2009) nternal nodes, logstcs flow, captal flow n coal supply chan system are descrbed and analyzed by the mathematcal language Mne nodes analyss (1) Varables descrpton of mne nodes: for mne seral number, = 1,2,... n; nput varables: XH ndcates the coal ash of mne, C o (Yuan / ton) ndcates coal mne producton cost, A (Tons) ndcates coal producton capacty for mne ; output varables: X ndcates coal producton of mne. X A (2) Constrants: coal producton capacty constrants: (1) Coal washng plant node analyss (1) Varables descrpton of the coal washng plant node: ndcates the seral number for the coal washng plant, = 1,2,..., q; l ndcates the seral number for commercal coal, l = 1,2,3,4,..., p, under normal crcumstances, 1 ndcates refned coal, 5 ndcates raw coal; nput varables: H l ndcates ash of commercal coal l produced by coal washng plant ; B (ton) ndcates the coal washng plant s capacty to wash and blend, C l (yuan / ton) ndcates the unts cost of coal washng of the coal washng plant, YH (%) ndcates the raw coal ash for washng of the coal washng plant ; Output varables: Y ndcates the quantty of raw coal to wash of coal washng plant ; L l ndcates the yeld of commercal coal l of coal washng plant, S (%) ndcates loss rate of coal washng plant. (2)Constrants: washng capacty constrant of coal washng plant: Y B (2) (3) Formulas of washng loss rate and coal output rate: Accordng to the hstorcal data, usng multple lnear regresson method to set up: The coal washng plant loss rate model: S = f ( YH, Ll, H l ) (3) The yeld rate of the man washng products : L1 = f ( YH, L2, L3, L, Lp ) (4) S + L l = 1 (5) l Varables descrpton of the customers needs Input varables: k for the customer seral number, k = 1,2,..., s; F kl, P kl (yuan/ton), D kl (%), E kl (tons) respectvely denote the demands of customers k to products l: the mnmum requrements for coal ash, quote, the lowest rate to meet orders and the demand Logstcs analyss of coal supply chan system (1) Varables descrpton of logstcs Mnes - coal washng plant: X (ton) for the volume of raw coal to be washed transported from mne to coal preparaton plant, the output varable. Mnes - customers: Z k5 (tons) for the coal volume to be transported from mne to customer k mne, the output varable. Coal washng plant - customers: Z kl for the number of commercal coal to be transported from coal washng plant to customer k, the output varable. Outsourcng coal - customers: H 0l for coal ash of purchased commercal coal l, nput varables; W l (ton) for the number of purchased commercal coal l,output varables; W kl (ton) for the number of purchase coal products l delvered to customer k, output varables; W k0 for the number of purchased coal delvered to customer k, output varables. Supply Chan Systems - customers: a (ton) for the coal supply chan system's transport capacty, nput varables; Q kl for the number of commercal coal l of coal enterprse sellng to customers k, output varable; Q k5 for the number of raw coal of coal enterprse sellng to customers k, output varables. (2) Logstcs balance and constrants of coal supply chan system The formula of coal mne producton quantty balance: X = X + Z (6) k 5 k

7 1614 L. Man-zh et al. / Proceda Earth and Planetary Scence 1 (2009) The formula of the quantty balance of raw coal to be washed of coal washng plant: The formula of the coal sale balance: kl kl kl Y = X (7) Q = Z + W (8) Qk5 = Zk5 + W (9) k5 The formula of purchasng coal balance: W = (10) l W kl k W k 0 = W kl l The constrants of Transport capacty: 4 Z + kl k 5 k l = 1 k The constrants of customer demands quantty: D E Z + W E D kl kl kl kl kl E Z α Z + W E (14) k 5 k 5 k 5 k 5 k 5 The constrants of customer demands qualty (ash): Z H + W H kl l kl 0 l Z XH + W H Q k 5 k 5 05 k 5 k 5 kl Q Captal flow analyss of coal supply chan system F kl F (1) Outflow of captal n the coal supply chan system Varable settngs: nput varables: S (yuan / ton) for the transportaton cost of unt weght from mne I to coal washng plant, Vk (yuan / ton) for the transportaton cost of unt weght from mne I to customer k, Rk (yuan / ton) for the transportaton cost of unt weght from coal washng plant to customer k, P0l (yuan / ton) for the prce of purchased coal l, Tk (yuan / ton) for the transportaton cost of unt weght from purchased coal to customer k, C0 (yuan / ton) for the cost of producton coal of mne I, Cl (yuan / ton) for the unt cost of coal washng of the coal washng plant. Outflows of funds: the cost of raw coal producton + coal washng cost + transportaton cost + cost of purchased coal XC + YC + ( Z R + Z V + XS + WT ) + WP (17) 0 1 kl k k5 k kl k l 0l k l k k l l (2) Inflow of captal n the coal supply chan system Coal sales revenues ( Z + WP ) + ( Z + W ) P (18) kl kl kl k5 k5 k5 k l k (3) Net nflow of captal n the coal supply chan proft Proft = formula (18) formula (17) (19) (11) (12) (13) (15) (16) 3.3. Coal supply chan mult-obectve optmzaton model constructon In the mult-obectve optmzaton of coal supply chan, mult-obectve on the part of customers (related to the qualty, quantty, transportaton, etc.) would act as the constrant condtons (see formula 12,13,14,15,16), the coal enterprses proft maxmzaton would act as the obectve functon; and accordng to the customers dfferent mportance and values to the coal enterprses, by coal enterprses usng fuzzy comprehensve evaluaton method. The dfferent degrees of supply securtes of coal enterprse to dfferent customers are determned, that s, the supply

8 L. Man-zh et al. / Proceda Earth and Planetary Scence 1 (2009) weght (n formula 13, 14, Dkl,Dk5? [0,1] [19]. The decson-makng optmzaton model of coal supply chan system could be establshed by usng lnear programmng, n whch formula (19) s as the obectve functon, the formulas (1) - (16) are the constrants. The model takes full account of coal external constrants and nternal condtons, may at any tme n accordance wth the changes of customer demand, the coal resource occurrence, producton, processng and so on nput varables, obtan the quantty and qualty decson-makng optmzaton nformaton ncludng producton of raw coal mnng, washng of coal washng, purchase of outsourcng, sales of customer segments of the supply chan lnk etc. The model also can promptly adust seres of decson-makng accordng to the changes n customer demand, so as to acheve dynamcs, from tme to tme mult-obectve optmzaton of coal supply chan system. 4. Conclusons In ths paper, the model of coal supply chan system s establshed by obect-orented Petr net from the perspectve of work flow. Based on the descrpton of the coal supply chan system, each obect s establshed correspondng to obect OPN, and then OPN model of coal supply chan system can be acheved through connectng obects OPN accordng to the nteractons between obects. Through the example confrmaton, by Usng the OPN modelng, the nternal structure of each obect OPN can be packaged, the defnton nterference of places and transtons can be avoded. The model has modular, graphcal, structural features, and has a good scalablty. Based on the coal supply chan system OPN model bult from the perspectve of work flow, the coal supply chan optmzaton s desgned. The coal supply chan optmzaton s consdered as a mult-obectve optmzaton, the obectves of whch nclude customer satsfacton and coal supply chan proft maxmzaton. The mult obectves can be converted nto the sngle-obectve of coal enterprse s proft maxmzaton for the selecton of resources and the envronment n a certan condton to meet customer demand. After the nternal nodes, logstcs flow, captal flow n coal supply chan system are descrbed and analyzed by the mathematcal language, the mathematcal model of the coal supply chan optmzaton s establshed by usng the smple, practcal and easy-to-use method of lnear programmng of optmzaton method. By usng the optmzaton model, accordng to nternal and external condtons, the decson-makng optmzaton nformaton of each node n the coal supply chan system can be obtaned, and tmely dynamcs adustments of decson-makng can be realzed accordng to changes of customers needs and other condtons, so problems related to mult-obectve dynamc optmzaton of the coal supply chan can be resolved. The model s hghly versatle. Acknowledgements Ths paper s part research result of Proect 08EYD024 whch s supported by the Socal Scence Foundaton of Jangsu Provnce. References [1] Q. Yua, Flow shop schedulng problem under uncertanty based on generalzed rough sets. Journal of System Smulaton. 12 (2006) [2] C. Peng, D. Yue, Study of obect orented structural descrpton of flow supply chan. Journal of Nanng Normal Unversty (Engneerng and Technology). 1 (2004) [3] C. Peng, D. Yue, The research of openng functonal structure of coal supply chan. Journal of Chna Coal Socety. 3 (2003) [4] J. S. Chen, L. J. Wang, Logstcs and supply chan unon of the coal enterprses. Management World. 11 (2004) [5] W. K. Yao, Characterstcs of even coal supply chan. Journal of Chna Unversty of Mnng & Technology (Socal Scences). 3 (2007) [6] C. Y. Yuan, Theory of Petr Net. Beng: Publshng House of Electroncs Industry, 199. [7] Z. D. Cu, Supply chan modellng and analyss based on generalzed stochastc Petr Nets. Systems Engneerng Theory & Practce. 1 (2005) [8] T. Murata, Petr nets: propertes, analyss and applcaton. Proceedng of the IEEE. 4 (1989) [9] K. Jensen, An ntroducton to the theoretcal aspects of colored Petr nets. Lecture Notes n computer scence. 803 (1994)

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