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Inventory Model of Two Sulphur Terminals
Client Requirements
Sultran Ltd. ships sulphur from 11 sulphur forming plans along three rail
routes to two Vancouver terminals. Sultran wished to investigate improved
inventory management at its terminals. Sultran has 7 members using its
facilities and handles three grades of sulphur. Important issues for
Sultran were:
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Equity among its
members, large and small, and;
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Security of scheduled
shipments.
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Accountability
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What Was Provided
Lauga & Associates carried out a simulation analysis to
test several candidate inventory models. A comprehensive report and
analysis were provided.
The Model
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The simulation causes
ships, to remove stock, and trains, to add stock, at the terminals as dictated
by the actual histories of trains and ships obtained from the Sultran Ltd.
operations database. The simulation reads in a lengthy and detailed data set of
train and ship information consisting of up to 15,000 records, each with 54 data
fields.
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The simulation works
on the basis of a timed sequence of events at the terminal. An event is the
dumping cargo by a train or the lifting of cargo by a ship. Because the
simulation is tracking timed events, it is able to spot opportunities for direct
hits. If, by fortunate coincidence, a train is dumping the grade that a ship at
the terminal wants to load, the simulation records an addition to the volume of
direct hits. The simulation also keeps track of vessel queuing, berth
occupancy, and dumper occupancy. The simulation is set up to change assumptions
about the number of dumpers, berths, terminals, materials handling rates,
numbers of grades, etc.
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The simulation creates
a product loan if a marketer has insufficient stock to load what a ship at the
terminal wants.
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The simulation creates
a space loan if a marketer has insufficient allocated space to accommodate what
is contained on a train that wishes to dump at the terminal.
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A marketer with a
product loan shows up in the simulation having a negative stock balance. As
train deliveries for the marketer come in, the negative balance is reduced in
much the same way as a bank overdraft is reduced by a deposit into the bank
account.
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The simulation
produces output that includes stock histories, berth occupancy histories and
information about stock loans, space loans and the use of terminal storage.
The simulation also tracks the age of inventory.
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The simulation is
capable of testing various development options for materials handling.
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The simulation is also
capable of expanding its scope to include upstream operations (by trains and at
plants) or downstream operations (by ships).
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Sultran
Ltd. exports sulphur from 11 forming plants along 3 rail lines to 2 export
terminals.

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