chương 4- sis
DESCRIPTION
efcdcaTRANSCRIPT
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HEÄ THOÁNG TOÀN KHO NGAÃU HEÄ THOÁNG TOÀN KHO NGAÃU NHIEÂNNHIEÂNNHU CAÀU ÑOÄC LAÄP NHU CAÀU ÑOÄC LAÄP (Stochastic Inventory Systems – (Stochastic Inventory Systems – SIS)SIS)
GV. ThS Nguyeãn Höõu PhuùcÑH BAÙCH KHOA – ÑHQG
TPHCM07/2012
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NOÄI DUNG
Moâ hình toàn kho ngaãu nhieân Toàn kho heä thoáng Toàn kho an toaøn Phaân tích thoáng keâ Heä thoáng toàn kho vôùi chi phí heát
haøng xaùc ñònh Möùc phuïc vuï Heä thoáng toàn kho khoaûng ñaët haøng
coá ñònh
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MOÂ HÌNH TOÀN KHO NGAÃU NHIEÂN
Moâ hình vôùi caùc tham soá ngaãu nhieân Nhu caàu (D) Thôøi gian chôø (L)
Nhu caàu laø bieán ngaãu nhieân tuy nhieân Nhu caàu trung bình khoâng ñoåi Phaân boá coù theå bieát tröôùc
Nhu caàu trong khoaûng thôøi gian chôø M Bieán ngaãu nhieân khi
D ngaãu nhieân L ngaãu nhieân D & L ngaãu nhieân.
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TOÀN KHO HEÄ THOÁNG Toàn kho heä thoáng
Toàn kho laøm vieäc (working stock ) Toàn kho an toaøn (safety stock )
Toàn kho laøm vieäc Kyø voïng toàn kho duøng trong thôøi gian chu
kyø Ñònh bôûi nhu caàu trung bình haèng naêm.
Toàn kho an toaøn Thöôøng khoâng phuï thuoäc löôïng ñaët
haøng Duy trì chæ nhaèm giaûm chi phí heát haøng Caân nhaéc chi phí heát haøng – toàn tröõ
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TOÀN KHO AN TOAØNTOÀN KHO AN TOAØN
Toàn kho theâm vaøo nhaèm traùnh heát haøng
Thoûa maûn nhu caàu trong thôøi gian chôø (M). Khi : Nhu caàu vöôït quaù nhu caàu kyø voïng Thôøi gian chôø thöïc vöôït quaù thôøi gian
chôø kyø voïng. Toàn kho an toaøn:
Giaûm chi phí heát haøng Taêng chi phí toàn tröõ
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TOÀN KHO AN TOAØN TOÀN KHO AN TOAØN Heä thoáng Q
M
LL
B
R
I
t
LL
Q
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TOÀN KHO AN TOAØNTOÀN KHO AN TOAØN Taêng löôïng toàn kho an toaøn laøm
giaûm xaùc suaát heát haøng Löôïng toàn kho an toaøn toái öu - cöïc
tieåu kyø voïng chi phí toàn tröõ chi phí heát haøng.
Chi phí heát haøng Ñôn haøng chaäm khaån caáp Khoâng baùn ñöôïc haøng Uy tín caïnh tranh Döøng daây chuyeàn…
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TOÀN KHO AN TOAØNTOÀN KHO AN TOAØN Möùc toàn kho an toaøn vaø ñieåm ñaët
haøng seõ lôùn Chi phí heát haøng / möùc phuïc vuï cao Chi phí toàn tröõ thaáp Nhu caàu / thôøi gian chôø thay ñoåi nhieàu
Moâ hình Löôïng ñaët haøng ñònh bôûi söï caân baèng chi
phí toàn kho & ñoäc laäp vôùi ñieåm ñaët haøng Toàn kho an toaøn ñònh khi bieát & khoâng
bieát chi phí heát haøng.
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TOÀN KHO AN TOAØNTOÀN KHO AN TOAØN
Phaân tích ñònh löôïng, toàn kho an toaøn :S = E[R]= B - E(M)= B-
R laø toàn kho cuoái tg chôø
R= B- M R thay ñoåi khi
Nhu caàu trong tg chôø M thay ñoåi Nhu caàu D thay ñoåi Tg chôø L thay ñoåi L & D thay ñoåi
M
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Phaân tích thoáng keâ
Phaân tích thoáng keâ Phaân boá lyù thuyeát Phaân boá thöïc nghieäm Nhu caàu trong thôøi gian chôø M
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Phaân boá lyù thuyeát
Phaân boá Normal Nhu caàu lieân tuïc Khoâng phuø hôïp khi nc. trung bình
thaáp Phaân boá Poisson
Nhu caàu rôøi raïc vaø thaáp Xaáp xæ pb. normal vôùi nc. cao
Pb. haøm muõ (Neg.Exp) Lieân tuïc trong toàn kho baùn buoân leû.
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Phaân boá thöïc nghieäm
M p(M)
150200250300350400450
0.010.040.210.550.090.070.031
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NHU CAÀU TRONG THÔØI GIAN CHÔØ
Toái öu heä ngaãu nhieân: Cöïc tieåu chi phí kyø voïng .
Nhu caàu: ngaãu nhieân vaø tónh Phaân boá nhu caàu const theo tg Kyø voïng nhu caàu Phöông sai nhu caàu Xaùc suaát heát haøng Kyø voïng löôïng heát haøng
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NHU CAÀU TRONG THÔØI GIAN CHÔØKyø voïng & Phöông sai
max
0
2
0
2
2
max
0
0
)()(
)()(
)(.
)(.
M
M
MpMM
dMMfMM
MpM
dMMfM
M
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NHU CAÀU TRONG THÔØI GIAN CHÔØXaùc suaát heát haøng
)(1)()()(
)(
)(
)()(max
1
BFBFBMPSP
Mp
dMMf
BMPSPM
BM
B
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NHU CAÀU TRONG THÔØI GIAN CHÔØKyø voïng löôïng heát haøng
max
1
2
2
)()(
)()(
)(M
BM
B
MpBM
dMMfBM
BME
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NHU CAÀU TRONG THÔØI GIAN CHÔØ Nhu caàu thay ñoåi, thôøi gian chôø khoâng ñoåi
B
Rmax
S = B - Ma
Rmin
LP(M > B)
t
I
Rmin = B – Mmax
Rmax = B - Mmin
Thôøi gian chôø khoâng ñoåi Ñoä bieán thieân nhoû Nguoàn cung caáp noäi taïi
R: Toàn kho cuoái thôøi gian chôø
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NHU CAÀU TRONG THÔØI GIAN CHÔØ Nhu caàu khoâng ñoåi, thôøi gian chôø thay ñoåi
Khi L thay ñoåi: B Lmin Heát haøng B Lmax Toàn kho
cao B La Khi L nhoû
B
S
Lmax
t
I
Rmax
RminLmin
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NHU CAÀU TRONG THÔØI GIAN CHÔØ Nhu caàu khoâng ñoåi, thôøi gian chôø thay ñoåi
Vôùi L lôùn, thöôøng duøng phaân tích thoáng keâ :M = D x L
D: suaát nhu caàuVd: D = 5 ñv/t ,
L(t) P(L)
34567
0.250.350.250.100.05
M (ñv) P(M)
1520253035
0.250.350.250.100.05
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NHU CAÀU TRONG THÔØI GIAN CHÔØ Nhu caàu & thôøi gian chôø thay ñoåi
B
Rmin
Lmax
t
I
Rmax
Lmin
S
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NHU CAÀU TRONG THÔØI GIAN CHÔØ Nhu caàu, thôøi gian chôø thay ñoåi
M = D x L
Moät phöông phaùp tìm phaân boá lieân keát
Moâ phoûng Monte Carlo
22222DL LD
LDMDIM
DLDL LD
LDMDNIM
22222
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NHU CAÀU TRONG THÔØI GIAN CHÔØ Nhu caàu, thôøi gian chôø thay ñoåi
D (ñv/ng) P(D)
012
0.30.50.2
L (ng) P(L)
12
0.750.25
M P(M)
01
2 34
0.2475
0.4500
0.2425
0.0500
0.0100
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NHU CAÀU TRONG THÔØI GIAN CHÔØ Nhu caàu, thôøi gian chôø thay ñoåi
M = D x L (0, 1, 2, 3, 4 ) P(M) ?Eg. M = 1
L = 1 , D1 = 1 : 0.75 x 0.5 = 0.3750L = 2 , D1 = 0 , D2 = 1: 0.25 x 0.3 x 0.5 =
0.0375L = 2 , D1 = 1 ,D2 = 0: 0.25 x 0.5 x 0.3 =
0.0375 P(M=1) = 0.4500
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HTTK. ÑÔN HAØNG CHAÄMBack Order - BOS Chi phí heát haøng ñôn vò
Khaùch haøng chôø khi heát haøng vôùi chi phí haøng chôø theo ñôn vò A
Kyø voïng toàn kho an toaøn:
Kyø voïng löôïng haøng chôø moãi laàn chôø:
B
dMMfBMBME )()()(
0
)()( MBdMMfMBS
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BOS Chi phí heát haøng ñôn vò
Kyø voïng chi phí toàn kho an toaøn haøng naêm
( )*S
RTC SH E M B A
Q
( ) ( ) ( )S
B
ARTC H B M M B f M dM
Q
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BOS Chi phí heát haøng ñôn vò
Ñieàu kieän toái öu
*
*
B
S B M
0 ( ) 0SdTC ARH P M B
dB Q
AR
HQsPBFBMP )()()(
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BOS Chi phí heát haøng ñôn vò
R = 1800 ñv/n, H = 0.30, A = 1 NÑ/ñv, Q=600 ñv
M P(M) M P(M)
48 0.02 54 0.20
49 0.03 55 0.07
50 0.06 56 0.06
51 0.07 57 0.03
52 0.20 58 0.02
53 0.24 Toång 1
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BOS Chi phí heát haøng ñôn vò
Kyø voïng nhu caàu :
Xaùc suaát heát haøng toái öu
1.018001
6003.0)(
x
x
AR
HQsP
53M
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BOS Chi phí heát haøng ñôn vò
M P(M) F P(S) = P(M>B)
4849505152535455565758
0.020.030.060.070.200.240.200.070.060.030.02
.02
.05
.11
.18
.38
.62
.82
.89
.95
.981
0.980.950.890.820.620.380.180.110.050.020.00
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BOS Chi phí heát haøng ñôn vò
Ñieåm ñaët haøng:
B = 56Toàn kho an toaøn
05.0)(]11.0,05.0[1.0)( BMPsP
* 56 53 3S B M
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BOS BOS Chi phí heát haøng theo laànChi phí heát haøng theo laàn
Khaùch haøng chôø khi heát haøng vôùi chi phí haøng chôø theo soá laàn.
Ñieåm ñaët haøng laø soá nguyeân lôùn hôn ñieåm toái öu.
GR
HQBf
BfQ
GRH
dB
dTs
BFQ
RGMBHTC
BMPGQ
RHSTC
S
S
)(
0)(
)()(
)(..
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BOS BOS Chi phí heát haøng theo laànChi phí heát haøng theo laàn
M ~ P()Vd: L = 1 t, = M = 5 ñv/t, N = 52 t/n, H= 5 ñ/ñv.n, G = 5 ñ, Q = 13 ñv
3
8
05.05525
135)(
S
Bxx
x
GR
HQBf
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BOS BOS Chi phí heát haøng theo laànChi phí heát haøng theo laàn
M ~ N(M, )
S = B – M = .z
Vd: L = 1 t ,N = 52 t/n ,M = 20 ñv , = 4 ñvH = 5 ñ/ñv.n , G = 10 ñ ,Q = 26 ñv
S = 2.03x4 = 8.12 = 8 ñvB = + S = 20 + 8 = 28 ñv
03.2
05.0205210
2654)(
zxx
xx
GR
Hzf Q
MB
z
)(.2
)(2/2
Bfe
zfz
M
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HTTK MAÁT ÑÔN HAØNG Lost Order - LOSChi phí heát haøng ñôn vò
Khaùch haøng khoâng chôø khi heát haøng vôùi chi phí heát haøng theo ñôn vò A
B
dMMfMBS0
)()(
)(
)()()()(0
BMEMBS
dMMfMBdMMfMBSB
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LOS LOS Chi phí heát haøng ñôn vòChi phí heát haøng ñôn vò
0)()(0
)()()()(
BMPHQ
ARH
dB
dTS
BMEHQ
ARMBHABME
Q
RSHTC
S
S
HQAR
HQSPBFBMP
)()()(
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LOS LOS Chi phí heát haøng ñôn vòChi phí heát haøng ñôn vò
Vd: Q = 1000 ñv, R = 5000 ñv, H = 10 ñ/ñv.n, A = 50 ñ/ñv
M P(M) P(M>B)
150200250300350400450
0.010.040.210.550.090.070.03
0.990.950.740.190.1
0.030.00
400038,0100010500050
100010)(
B
xx
xSP
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LOS LOS Chi phí heát haøng theo laànChi phí heát haøng theo laàn
Khaùch haøng khoâng chôø khi heát haøng theo laàn G
)( BMEMBS
GBMPQ
RHSTCS )(
)()(.)( BMPQ
GRBMEHMBHTCS
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LOS LOS Chi phí heát haøng theo laànChi phí heát haøng theo laàn
GBMPQ
RHSTCS )(
)()(.)( BMPQ
GRBMEHMBHTCS
0)()(. BfQ
GRBFHH
dB
dTCS
GR
HQ
BF
Bf)(
)(
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HOAÏCH ÑÒNH TOÀN KHO AN TOAØNMoâ hình möùc phuïc vuï
Xaùc ñònh ñieåm ñaët haøng khi khoâng bieát chi phí heát haøng
Möùc ñoä thoûa maõn nhu caàu. Möùc phuïc vuï caøng cao:
Möùc thoûa maõn nhu caàu caøng cao. Ñaàu tö toàn kho caøng lôùn.
Phaân loaïi: Phuïc vuï theo chu kyø ñaët haøng Phuïc vuï theo ñôn vò nhu caàu.
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HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo chu kyø
Möùc phuïc vuï: Tæ soá giöõa soá chu kyø khoâng
heát haøng treân toång soá chu kyø
)(1 BMPSLC
MMMBS a
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HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo chu kyø
M P(M) F(M) P(S)
30405060708090
0.0250.10.2
0.350.20.1
0.025
0.0250.1250.3250.6750.8750.975
1
0.9750.8750.6750.3250.1250.0250.00
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HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo chu kyø
60M
SL = 87.5% P(S) = 1-SL = 0.125 B = 70
S = 70 – 60 = 10 Kyø voïng löôïng haøng heát
90
70
5.1)()()( MpBMBME
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HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo chu kyø
Vd: M ~ N(M=60, =20 ), SLC = 95%
P(M>B) = 0.05 z = 1.64 B=M + z = 60 + 1.64x20 =
92.8 ( 93 ñv) S = B - M = 93 – 60 = 33 ñv
![Page 44: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/44.jpg)
HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo chu kyø
Vd: = 2 ñv/ng, M ~ P(M), L = 4 ng, SLC = 96.6%
M = D L = 8 ñvP(M>B) = 0.034 B = 13 ñv S = 13 – 8 = 5 ñv
D
![Page 45: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/45.jpg)
HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo chu kyø
Vd: D = 2 ñv/ng, M ~ E(M), L = 4 ng, SLC = 95%
M = D L = 8 ñvP(M>B) = 0.05 B / M = 3 B =
3xM = 24 ñv S = 24 – 8 = 16 ñv
![Page 46: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/46.jpg)
HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo ñôn vò nhu caàu
Möùc phuïc vuï:Phaàn traêm nhu caàu ñöôïc thoûa maõn
Ñôn haøng chaäm Ñôn haøng maát
1
)1()(
)(
)(1
)1()()(
1
u
u
u
u
SL
SLQBME
BMEQ
BME
SLQBMEQ
BME
SL
![Page 47: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/47.jpg)
HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo ñôn vò nhu caàu
Vd: SLu = 0.99,
Q = 60
M p(M)
4849505152535455565758
0.020.030.060.070.200.240.200.070.060.030.02
![Page 48: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/48.jpg)
HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo ñôn vò nhu caàu
E(M>B) = Q(1 – SLu)
= 60(1 – 0.99) = 0.6 (ñv)
E(M>B) = 0.6 B = 54
max
1
)()()(M
BM
MpBMBME
B E(M>B)
58575655545352
00.020.070.180.360.741.36
![Page 49: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/49.jpg)
HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo ñôn vò nhu caàu
Neáu M ~ N((M, ): E(M>B) = .E(z)
.
)1()(
)(.1
ZMB
ZSLQ
zE
Q
zESL
u
u
![Page 50: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/50.jpg)
HOAÏCH ÑÒNH TOÀN KHO AN TOAØN Möùc phuïc vuï theo ñôn vò nhu caàu
Vd: SLu =0.99, Q = 60 ñv, M ~ N(M=53, =2 )
z = 0.22 B = 53 + 0.22x2 = 53.4 ñv (54 ñv).
S = 54 – 53 = 1 ñv
3.02
)99.01(60)1()(
xSL
QzE u
![Page 51: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/51.jpg)
MÖÙC PHUÏC VUÏ Chi phí heát haøng qui ñoåi
)(.)(
BMPR
HQA
AR
HQBMP B
Chi phí heát haøng qui ñoåi Qui ñoåi töø möùc phuïc vuï Ñaùnh giaù söï phuø hôïp cuûa möùc
phuïc vuï Ñôn haøng chaäm
Ñôn haøng maát)(.
)](1[)(
BMPR
BMPHQA
HQAR
HQBMP L
![Page 52: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/52.jpg)
MÖÙC PHUÏC VUÏ Chi phí heát haøng qui ñoåi
67.2125.0000,18
12005
x
xAB
33.2125.0000,18
)125.01(12005
x
xAL
Vd: H = 5 ñ/ñv.n, R = 18,000 ñv/n, Q = 1200 ñv, SL = 87.5%
![Page 53: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/53.jpg)
Moâ hình (s-S) Giaû söû M ~ N(M ,M) Möùc toàn kho – IP
Toàn kho saún coù Löôïng haøng ñaõ ñaët Löôïng haøng chôø
Moâ hình cöïc ñaïi – cöïc tieåu (s,S) Toàn kho an toaøn
SS = zM ; z Möùc toàn kho cöïc tieåu – Ñieåm
taùi ñaët haøng:
s = M + SS Möùc toàn kho cöïc ñaïi
S = Q + s
% z
90919293949596979899
1.291.341.411.481.561.651.751.882.052.33
![Page 54: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/54.jpg)
Moâ hình (s-S)
L ~ ND (L,L) , D ~ ND (D,L) M = D*L M= D * L
M= (LD2 + DL
2)
![Page 55: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/55.jpg)
Moâ hình (s-S) TV distributor case
L = 2t = 97% Q = 679 u
z=1,88 = 44.58 u/w = 32.08 u/w M = 89.16 u SS = 86.2 u s = 176 u S = 765 u
m sales
910111212…8
200152100221287176…
156
![Page 56: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/56.jpg)
HEÄ THOÁNG TOÀN KHO KHOAÛNG ÑAËT HAØNG COÁ ÑÒNH
Heä thoáng T ( T_systems) Tham soá:
Khoaûng ñaët haøng T Möùc toàn kho cöïc ñaïi E
Phaân tích töông töï heä thoáng toàn kho löôïng ñaët haøng coá ñònh (fixed order Quantity Systems _ FOQS / Q_Systems)
M: nhu caàu trong toång thôøi gian chôø vaø thôøi gian chu kyø
Khoaûng ñaët haøng:
RHCRQT /2/**
![Page 57: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/57.jpg)
HEÄ THOÁNG TOÀN KHO KHOAÛNG ÑAËT HAØNG COÁ ÑÒNH
Moâ hình chi phí heát haøng
Chi phí theo ñôn vò
Chi phí theo laàn
Ñôn haøng chaäm
Ñôn haøng maát
P(M>E) = HT/A
P(M>E) = HT/(A – HT)
f(E) = HT / G
f(E)/F(E) = HT / G
![Page 58: Chương 4- Sis](https://reader036.vdocuments.pub/reader036/viewer/2022062515/563db8de550346aa9a97b59c/html5/thumbnails/58.jpg)
HEÄ THOÁNG TOÀN KHO KHOAÛNG ÑAËT HAØNG COÁ ÑÒNH
TR
EMESL
EMPSL
u
C
)(1
)(1
Moâ hình möùc phuïc vuï