• 검색 결과가 없습니다.

 Optimal Scheduling of Quality Controlled Product Storage   

N/A
N/A
Protected

Academic year: 2022

Share " Optimal Scheduling of Quality Controlled Product Storage    "

Copied!
8
0
0

로드 중.... (전체 텍스트 보기)

전체 글

(1)

    

*** *** *** ****

  

*   

**    

***  

****  

(2000 2 9 , 2000 11 10 )

Optimal Scheduling of Quality Controlled Product Storage

Gyeongbeom Yi, Dongil Sin*, Ho-Kyung Lee**, Bom Sock Lee***, Jin-Kuk Ha**** and Euy Soo Lee****

Dept. of Chem. Eng., Pukyong National Univ., Pusan 608-739, Korea

*School of Chem. Eng., Seoul National Univ., Seoul 151-742, Korea

**Automation Research Center, Dept. of Chem. Eng., POSTECH, Pohang 790-784, Korea

***Dept. of Chem. Eng., Kyunghee Univ., Yongin 449-701, Korea

****Dept. of Chem. Eng., Dongguk Univ., Seoul 100-715, Korea (Received 9 February 2000; accepted 10 November 2000)

 

9: ;# #< = 6# > ?@A B. C 9/ 45 012 D@ 45 6#7 EDFG HI

 ;#D@ > 6#DFG JK LMDNO 45 6#7 isocontainerP QR ST LMU. 012 block mode VWDX, Y Z 45. 6#7 [U. 8 / \]  45. ^_ / 6#7P `aMX, !

6#7G a D@ BO, 2 bc 6#7 bc 45 R de f B.   gh. @i 45 0 12 6#7 [U j 3-15' kl 5m noP pqMX,  2r kl Rs 6#7 tm Lu vaU

 w.  , x. yI qrz #< {\| } ~$ €< 5mno fP ‚M ƒ

.   # R „( f …† ‡$ \M^  b†$ /ˆM‰. C Š ‹fG 1,500-2,000 / ŒM‰X, f)$ Ž2 M^  f‘ z $ ’M^ a‹f “… ”P M‰.

Abstract−The mixed integer linear programming model has been developed for the production scheduling of liquid state polymer process such as a Polybutene(PB). The example process is composed of one reactor, twelve storage tanks and two package types. The reactor produces 9 liquid state products. The products are reserved in tanks and then, packaged into drum or isocontainer. The drum products are stored in a warehouse before they are shipped out to customers but the isocontainer prod- ucts are shipped directly out to customers. Two major products use multiple tanks. Most tanks are dedicated to a certain prod- uct but basically any tank can be shared by any product. The reactor is operated on block mode. The unique characteristic of this scheduling problem exists on the fact that the product in a tank should be locked for 3-15 days in order to check the quality specifications after run-down from the reactor. The primary objective of scheduling is reducing the number of quality checking processes because it causes great loss in production time and tank utilization. The model is composed of about 1,500-2000 inte- ger variables. The branching priorities are adjusted according to the importance of variables based on current manual sched- uling practice and it greatly enhanced the convergence of the mixed integer model.

Key words: Optimal Scheduling Quality Storage Block

E-mail: [email protected]

(2)

1.  

       !"# !" !

$% &  ' () *+ ,- ./ .0 123 4 5 67 89: ;<. = >?

@A 5B< <'C "D E3 FGH, Polybutene(PB) 5B I 9J KD L  F.  !" M- N!O PQ RSD M+E T; 3U !" 5BGDVW  X< Y@E Z[ 4@\  ]@ Y@( ^_` ab  cB RC b d L3 (H <   ef 3g 15g Bh i.

. <  Z[ !" X <Z< j. bd< ^_

@  << ]G`  4@\  F. .0< k 

 ' l !"m -+GD no p+@ .0< qO 9

 L C l !"  ' < 5oC. Xr s t L $% &D !" C () u vo\  F@

" +0| l CE3 F. ( }.C ~B 5B   3€ !"D \=\ J(  n<. < \=< ‚

ƒ„ …† x !" <‡ L< ˆ)@ F3 ‰y 5B   vP\ !"( ]3) M-p@( Š \  F

. 5B| bd i.E b)< ‹ T; @Œ

12) ƒ Š  ‘o’ “ R *  y

@m ”  • < y@ z+ –(m —˜@  y@D J C  !m —˜H B™:š   5 …† g

9GD y@ 5< CE3 F. <'C 67; C 89 :s› lŠ < <  œI<.

‰ ‘† ‰’9J ;ž h Ÿ@ <'C p[  C  ¡9J š¢9J m :š5š;£ Ф ¥D Ž ) . D w 5BL  X¦§ Ÿ¨› ©, S !

" 9J ª C š¢9J  «@;£[1-11] _

¬­ ®# ¯< 8° ±² 5B PC  Š-| ³Ÿ3 ´ŠO -lE@ F. )µ¶) E3· !" M-o› ¸ v`

¹L p< ,C +0 !"m º UIS(Unlimited Intermediate Storage) »[, -¼ } !"m ½¹)  NIS(No Intermediate Storage) »[, oCC +0 !"m ½¹ FIS(Finite Intermediate Storage) »[, ' () } !" »[ p+ MIS(Mixed Intermediate Storage) »[, _ } !"m ' l ¹L<

5jGD p+ CIS(Common Intermediate Storage) »[, ¾Q@ !

" vP \ …† !m oŠ :š RC ZW(Zero Wait) »[ ¿< F.   ’ :š 6 x y)u R 3U o› h À)   !" MÁ»[GD QCPS(Quality Controlled Product Storage) »[ b@/ C.

a QCPS !"( y@ vP| 4 ª Âu ÃÄf PQ

 ª Å …†<.

2. 

  I9J $ @/ 5BJ ÆQVÇ 5B GD lŠEÈ. ÆQVÇ <iVÉÊ 0%D  !Ë Ì‘ }>

C ÍC !/0 $ @/<. C4 Îpom ÏÐD  H, ¡Ñ, ÒÓ Ô ’Õ Ö>yÐ, ×§ Ø(, - Ù, ,

@A Ø(, ÃÚÛÜ l, ÝÞ ßào, ² Ø( ¿ p+

. " 5B Fig. 1 hb ®# ¯< C l  # 12l !

"D ?E3 F. á 9l 8â  H, ã 8â 

i0J …† äå æç è@ !EÈ( 4Eé_ +0 @

Œ<_ 4  isocontainer ’ê ®D 4.  5B

 SÏÐ V 5B E3 ÏÐ !" !EÈ( 5

-E)u < ®ì íîM- H, 8/8i Àh  ï< F. Àh( –(\î   M-z )9GD –(

C.   ®ð T ëC X? :( ñ+E)

  !"D <ôE3 õpm öà C. Ï÷

9GD 3U !" 3U  äb ! \ <o ]. ¾ '_ vj ‘0< k < ø !"m ˆ)ù E@ ‘0<

ÃS k SâL  !"m noù . V !

" C l   -+E3 F. ¾'_ C !" 

º l <  Zb !\  ])u gV !"

" < Y@E` ý®D õp L3( • < < v j 3g 4 …† 15g< þÿ. < Z[ ‹ 

 4@_ Y@( <3   ]. ef ã !"  Y

@, , 4@( ûüà E< .  m *ß ã !" 

 X <ô þQ b Ab. äå  Ô 4 S}

u <3 ·. uï S<_ 5g   ` 2( žµ

< )ëE3 C. äå á 0 ï< F@, äå 6 

?  º () < w  \  ]. äåGD *

  è@ 8i 2 g vP  4 H, è@ ‹ CE3 F.

3.

  J ÆQVÇ 5 67  g9GD œ9ß

m ?\  F …? < A‡@ 5B MÁ ï "

< ‘† k  ()@ F. 67 œ9ß ‘<

Fig. 1. Polybutene plant block diagram.

(3)

 39 2 2001 4

z+ C ò<  8:é_ ÏÐ ‘z+, ‘o’

z+, M-z+, y@ o)z+ ¿ z+ > 8i: GD

½B < vj<. ¾'_  5 …† <'C z+ B<

‰’9GD Ÿ(ªé_ A‡. ! ‘< | ÏÐ ‘z+

 Kc .0 sº 5ëC@ (B C @B9<. ‘ o

’<_ g Ν PQ)à  6 @êE)  . y@ o )z+ -%9J !b½ +0< CE3 F@ 9GD !

D Abh . M-z+ œ }  67 @ê<

E    (Z< –„î z+< )9GD –(

D (Z gBù o) |  k b| z+<

isED (ªC  m < <. <}  ( Z ew z+Š  B0:( (ª_  z+ B0: \

 ]. <å 9GD ‹@ E)u B0:( Ÿ(ªC z +œ< xy\ …† ò< 8:  á z+ 8i:f g9 J 67 œ9ß 9+( Ÿ(ª. œ9ß( æ=

é gBhî ï²< V(EH, !" M- PC ï 

 m < • —n< ¼ F. ‘o’h Š \  ]

 |C M-ï  st ï² u  xy ( Ÿ(ªù . ef  89: s› œ9ß <'C 

Ÿ(ª? 8i: <. Ÿ(ª?| P ï² 9 z } p+/  B C.

 gB67  C RD <3 )H, 8i ggR

X0<Z C 6~|( _# C. ’   67

³ ™C b C @ê( .E_ gg R  M-6 7< ~BE` C M-67 2 ˆ9GD 6„  F. 6 7< C RD 6E@ E <o ±p PQ % C

RD ±6Qm @ F@, A vh 67  S.C Y! /ÐJ .Kc /Ð( C RD E T;<. g9 GD @/ 5B  gB67 s› block mode M-  

m p+C(Karimi and McDonald[6]). ¾'_    v !" M-< ³ }.H À b s› !" M- 9+\ …† 60< |ù –D ï² -%9GD <

b(mluti-period) "m p+@ F. ï²L ã ¹  C X 4Y| ¹ +0 _¬ú ²| ¹ "B,  ò , M- XQ9J ï æ@ F. ã ï² C ½# Ï ÐVW ¶) X ¦§ ef ½#\ <.

;? RC 9 Ïi $ 4()D ¸.

i:   œî p: * © œî k: !" œî t: g/ œî

 i(  !" kD oYE t g/ X0 FQiktf º

@ <· YFQiktm FQikt( Í<` 1, 0<` 0<f@ BC. ¾Q

@   i( g/ t E` <· Yit( 1, ¾%) G

` 0GD BC. ¾'` <· FQikt# Yit p< $ P6²<

?C.

(1)

¾Q@   i - <3 \  ] L &

> NTC(i, i')f@ \ T

(2)

 gg 8/8i 0 ï< F. ¾'_ V'<C …†

<'C "  ©:„  F.

(3)

 Í α, β ï² Ÿ(?(infeasibility) _¬úH, œ9 ß 8i: .

g/ t 24:00 bn  i( !" k ! X0 FIiktf º

@ <· YFIiktm FIikt( Í<` 1, 0<` 0<f@ BC. ¾Q@

 i( !" k * R 4@E t g/ X0 FHiktf º@ <· YFHiktm FHikt( Í<` 1, 0<` 0<f@ BC. 3 U !" k µg y@0 -( y@0 µg Y@0 ³@

µg 4@0 ) | ¯. <m ²GD I‰`;

(4)

<·m B ²L $| ¯.

(5) (6) (7)

 TKMXik  i( !" k !„ T 8 !0<.

*C !" M- I‰ R ´Z }+(production spill- over) _¬ú ,DM <· YSiktm hYC. YSikt uï  i ( !" k g/ t# g/ t+1 À Y@„ …† 1<@ ¾%)

G` 0< . < ²GD I‰`;

(8) (9) (10)

 DVW  Y@( ^_/ -/ !" y@0  

  ’bH <  Z[ ,DM  Y@_ 4@( µ ). <'C XQ9 ï $| ¯< I‰.

(11) (12)

 m < R (ªC 3U !"( (' .{

 T¶)  6ÀH   ’bC !" é  z/

T¶) ,D Y@ g< ]3 C. b `  Y@( ^ _ ò ¾ !" y@0 !" 8 ‹ 80%m ±

@,  Y@( bE ò ¾ !" y@0 !" ®0 ÎX0v à C. <'C …d9J M- ÷ 1C po(

] C 2E3 C. <L ²GD I‰` $| ¯.

(13) (14)

 δ, γ ï² Ÿ(? _¬úH œ9ßm j 8i

: .

C l !" º () < < Zb !„  ].

<'C XQ9 ï $²GD I‰.

(15) Yit YFQikt

k

=

Yit+Yi't≤1 ( )i i', ∈NTC i i'( ),

RXMAX α FQikt≥RXMIN

k

i β

≥ +

FIikt=FIikt 1 +FQikt–FHikt

FQikt≤TKMXik*YFQikt

FIikt≤TKMXik*YFIikt

FHikt≤TKMXik*YFHikt

YSikt≤YFQikt YSikt≤YFQikt 1+

YSikt≥YFQikt+YFQikt 1+ –1

YFQikt′+YFQikt≤1+YSikt t t' t LAG i< < + ( ) YFHikt′+YFQikt≤1 t t'≤ <t LAG i+ ( )

FIikt+δ≥0.8*TKMXik* YFQ( ikt–YSikt)

FIikt–γ≤TKMNik+TKMXik* 1 Y( – FQikt 1+ +YSikt)

YFIikt≤1

i

(4)

!"DVW  4@ º () ›&D <3 ·. _ ä åGD *E3 è@ vPE <@, w _ !"DVW isocontainerD *E3 ôˆ0 j @Œ ù ®D 4E <

. g/ t  è@ *  p( Y@E X0 PQptf º

@ *  C @Œ . Kc0 Dptf@ \ T äå 

…† = < æç F !" 4@ X0 è@ Y@

X0| g¹\ <H, isocontainer …† = < æç F !

" 4@ X0 @Œ . Kc0| g¹ C. @Œ S

;‡ Ï÷9GD ñ+E) )u  67 °9GD Ÿ(ª C …†( F. <m Á R S;‡0 BLpt hYC. S

;‡ ( 8i:E3 \ D œ9ß 2(„ <.

(16)

(17)

ú@, DRUM(i) äå *   œî _¬úH, ISOCON (i) isocontainerD *  œî _¬3. ¾Q@ LAG(p)

* C 4  [B:m R 4m µ g/ =C.

äå * / 5Z! xD g/1D +0ï< F

. a g < <3 ))  .

(18)

 λ ï² Ÿ(? _¬ú GD œ9ßm j

8i: . ¾Q@ CAPt g/1 8 * +0 _¬3.

äå * < ®ì` ,DM  2z b< isED

 º () < u *\  F. <'C ï 3U 

< !"DVW 4@ oAm _¬ú ,DM <· YHFitm hY

 $ ²GD I‰.

(19)

(20)

(21)

è@ 4E X0 SHptf@ \ T è@ ! äå 

 y@0 $ ²GD 6.

(22) äå   h S; ‡ ñ+E) )u ’D Š 

D $ ²< 2(.

(23) (24)

è@ !E äå  á0 è@ á ! +0 MXWHS ï ö .

(25)

 89: s› œ9ß B ï² Ÿ(? > 8i:

 <.

 wα,..., wBL 㠟(? C (}¹D p+/  ~ B.

4.   

  89: s› GAMS/OSL# Pentium III(500 MHz) p + lŠEÈ. Y!/Ð ’ ÆQVÇ 5 "/Ðm ® 6GD 4 ˆ7 &EÈGH, ãã …† lŠ s› j69 /Ð Table 1 .ïE3 F. Table 1 _¬­ å s› ­<hm

I <· l( 1,500-2,000GD 6 bh 30  1 b  › 8> B 679 s›<. :; 6 ~| 

 l <= k)u 6 b ‘† > K¥9J …†J• <

 (Z})(shut-down)m *ß@ F T;<.  s› ( Z})  w   _D 1O ?ë. @; bd6

 st !" C l u \=EÈ@, A; bd6 ºl

!"( 2l   5oEÈGH, B; bd6 C l

!"( º l   5oEÈ. <m <· l# ~ V zC D T ; ‹m ~B ( ø .J º l <

 < 5o !"(swing tank) lJ  E  F. a 5o !"( _ ”3(î <·( ï 10%F ”3­. 5o

!"( 3l <g …† ‰’9GD 89: s›  3G. H Oh 67 @ê J 1  <ú º l < !"m 5o

   ‘† <79<@ V …† ã !" 67

J 1  Z[ C l u ‡Q )BE3 F@ (B

h AQ( ]. ã !" ‡Q  )Bß h Ÿ@  8 9: ; <· ( 1,500 l <J › 8>B679GD vj »9GD  < Ÿ(ªI. ) C69(branch and bound) ) †"òR(branching priority)m "Ù` Žù  \ h F p’ ‚ Eê F)u ’D 9ÙC ) †"òRm Š

¤ g Ž) . †Q 9ÙC †" òRm  R

67  و# opC ò D ã و P <· 

ò m VI. <'C   C <·  ) †" ò R $| ¯.

(1) Sâ | P <·  z Sâ | P <· 

 z J †" òRm 2.  Sâ <K  X0<

9GD ké_ *+( isocontainerJ å 67 

 ~B9J ÁL ‡¹  ‡C.

(2) V5B a @Œ . (¶M  C †" òR( V 5B  ÏБ (¶M  C †"òRv J.

(3) b …| ef  †" òR( M÷.

R (½ C <·  †" òRm 9+C ~| [B  FHikt

k =PQpt LAG p+ ( ) ( )i p, PACK i p( ),

i∈DRUM i( ) BLpt BLpt 1 Dpt− FHikt

k

+

= ( )i p, ∈PACK i p( ),

i∈ISOCON i( )

FHikt≤CAPt

k

iDRUM i

( )

YHFit YFHikt

k

YHFit 0.1* YFHikt

k

≥ YFHit

iDRUM i

( ) 2

PIpt=PIpt 1 +PQpt–SHpt p∈ DRUM p( )

BLpt=BLpt 1 +Dpt–SHpt p∈ DRUM p( ) SHpt′

t′

t Dpt′

t′t

PIpt

pDRUM p

( ) MXWHS

MIN wαα wββ wδδ wγγ wλλ+wBL BLpt

p t,

+ + + +

Table 1. Model statistics of test runs Test run

no.

Number of equations

Number of variables

Number of binary variables

CPU time (sec)

1 17880 7856 2202 1432

2 13280 5009 1526 2932

3 12416 5848 1999 5465

4 12130 5451 1725 4322

(5)

 39 2 2001 4

? N  FÈ. <¥ h GAMS/OSL< 5 O () "P pÍ ‚ "ÙßGDQ 6b g  FÈ. ¾'_ s›  ? R† }.C .J  l_ E@QS :v

89: s› š9J "f < !/L …d9 ~r<.

4û; bd 6 ~|J   gB, ‹ Y@ Ô 4@, 

‹ y@ Z, ! è@ Y@ Ô 4@, ! è@ y@ Z

C Gantt Chart Ô y@ ¾TI( Fig. 2-7 _¬_ F.

5.  

$ @/ 5B  gB 67 89: s›< lŠEÈ. $

@/ 5B   Y/ & w @/ 5B| Q 

!" MÁ< ‘† * 67 ø ÁL ‡U. <'C

? $% &D EH,   b< i.E :š 

 5j9GD _¬­. Km L3 Bo 5 (Vÿ, ¿o, …o Fig. 2. Reactor schedule.

Fig. 3. Reactor run-down schedule.

(6)

Fig. 4. Inventory profile of storage tanks.

Fig. 5. Packaging schedule.

(7)

 39 2 2001 4

¿ Ðo Ö> <_ W´o  Ö>  h  !

" y@ X0 vP X\| Ö>  Ô   RC 5 B X\ Å@ F.   Y/ &D E @/ 5

b s›< 9+E)u $ @/ 5B  !" M-

 Y|9GD I‰\  F < b s›< 9+EÈ. g9 Fig. 6. Warehouse inventory profile.

Fig. 7. Product demand.

(8)

GD 67 œ9ß ?.im < M-z+, y@ o)z +, ‘ o’z+ ¿  z+ œ Y! /Ð Ÿ[’?GD J

 B[C B< Ÿ(ªé_ 5 MÁ »²  ¡9GD @ê\

×.( ]È. ¾ 5 MÁ ø z+ Š  .JGD )œE

 ½BC $ <'C ï² ub]) ƒ Ÿ(? Bh m œ9ßD ½B 8i:hî ^. a <} ( }.C p

  m <@/  œ9GD œ9ß <m ¡

 ò , !" "P, !" MÁ XQ9J ï, Ö>

, !" +0 ï, *b½ ï| !" Ô è@ y@ ¨›²

¿ *ß@ F.

’ ÆQVÇ 5 "m ®6GD 89: s› ?C ~|

<·( 1,500-2,000l  › 8>B 679 s›< 

EÈ. s›  ? l" R ) †" òRm ~B  1C »9 9+I. ’ " /ÐDVW Y!/Ðm 2z 4

ˆ7 bd 6 ~| 67 ’A/# opC ?ª vI.  5

 ? 67 œ9ß( Ÿ(? 8i: < T

; (b9J Y| ]È)u 67 6b< GD 2 gBh þQ_  2 b <úD g  FÈ.

 

  C`|šy B—(|ûa 1999-1-307-002-3)

z )Ï  <3bGH )ÏS C`|šy cp ä

Ä.



i : index for reactor products p : index for packaged products k : index for tanks

t : index for time periods

BLpt : the backlogging quantity of packaged product p at the end of period t

CAPt : is the drumming capacity of period t

Dpt : the customer demand of packaged product p at period t DRUM(i) : the subset of reactor products with drum package FIikt : the inventory hold-up of product i in tank k at the end of period t FHikt : the discharge quantity of product i from tank k at period t FQikt : the quantity of product i moved from reactor into the tank

k at t period

ISOCON(i) : the subset of reactor products with isocontainer LAG(i) : is the quality checking period for product i LAG(p) : the time delay for drumming

NTC(i, i') : the set of pairs of reactor products that can not be produced in sequence

PACK(i, p) : the connection between reactor product and package product PQpt : the drumming quantity of packaged product p at period t RXMAX : maximum daily production rate of reactor

RXMIN : minimum daily production rate of reactor

SHpt : the shipping quantity of packaged product p at period t TKMXik : the maximum storage size of tank k for product i wδ,..., wBL : the weighting factors for infeasibility of relevant constraints Yit : is set to 1 if product i is produced in reactor at t period,

otherwise 0

YFIikt : is set to 1 if FIikt is positive, otherwise 0 YFHikt : YFHikt is set to 1 if FHikt is positive, otherwise 0 YFQikt : is set to 1 if FQikt is positive, otherwise 0

YSikt : is set to 1 if product i is continuously fed from reactor to tank k at period t and period t+1, otherwise it is set to 0 YHFit : is set to 1 if product i is packaged into drum at period t,

otherwise 0

δ, γ : the infeasibility of the relevant constraints



1. Cho, I., Lee, B., Lee, I. and Lee, E. S.: HWAHAK KONGHAK, 36, 601 (1998).

2. Ha, J. K., Lee, B. S., Lee, I. and Lee, E. S.: HWAHAK KONGHAK, 36, 813(1998).

3. Bok, J. and Park, S.: HWAHAK KONGHAK, 37, 531(1999).

4. Jung, J. H. and Lee, H.: Computers Chem. Engng, 20, 845(1996).

5. Jung, J. H., Lee, H., Yang, D. R. and Lee, I.: Computers Chem. Engng, 18, 537(1994).

6. Karimi, I. A. and McDonald, C. M.: I&EC Res., 36, 2701(1997).

7. Ku, H. M. and Karimi, I. A.: Computers Chem. Engng, 14, 49(1990).

8. Park, S. and Jung, J. H.: HWAHAK KONGHAK, 37, 411(1999).

9. Wiede, W. Jr., Kuriyan, K. and Rekalitis, G. V.: Computers Chem. Engng, 11, 337(1987).

10. Wiede, W. Jr., Kuriyan, K. and Rekalitis, G. V.: Computers and Chem.

Engng, 11, 345(1987).

11. Wiede, W. Jr., Kuriyan, K. and Rekalitis, G. V.: Computers and Chem.

Engng, 11, 357(1987).

참조

관련 문서

• 대부분의 치료법은 환자의 이명 청력 및 소리의 편안함에 대한 보 고를 토대로

• 이명의 치료에 대한 매커니즘과 디지털 음향 기술에 대한 상업적으로의 급속한 발전으로 인해 치료 옵션은 증가했 지만, 선택 가이드 라인은 거의 없음.. •

혼합제를 사용하여도 천식 조 절이 되지 않는 경우 경구 약제인 류코트리엔 조절제 그리 고 (또는) 테오필린을 추가하여 사용한다. 류코트리엔은 효 과 면에서는

12) Maestu I, Gómez-Aldaraví L, Torregrosa MD, Camps C, Llorca C, Bosch C, Gómez J, Giner V, Oltra A, Albert A. Gemcitabine and low dose carboplatin in the treatment of

Levi’s ® jeans were work pants.. Male workers wore them

The main function is to look over generally on all aspects of all the projects particularly on project planning, time scheduling, quality of work, workers productivity

In this case, the cause of paraplegia was presumed to be delayed epidural hematoma or abscess that developed three days after the placement of the thoracic epidural lead for

In this paper, the exact formulae for the generalized product degree distance, reciprocal product degree distance and product degree dis- tance of tensor product of a