### Logistics Engineering

 ÇANKAYA UNIVERSITY Faculty of Engineering _________________________________ Department of Industrial Engineering Yukarıyurtçu Mahallesi, Mimar Sinan Caddesi, No:4, 06790, Etimesgut, Ankara, TURKEY

IE 555 – Logistics Engineering
Spring 2022
Homework # 1
Due: April 20, 2022 (Wednesday); 11:00
XYZ CARGO INC. is a large company serving throughout Turkey. Its head office is in Istanbul, and it has 40
regional provincial directorates throughout Turkey and many branches in each region. You are an
engineer working at the headquarters of this company.
The administration wants to serve 25 predetermined regions. Some of these regions will be designated
as cross-docks.
A. Such an assignment has no additional costs. Explain with justification what appropriate site selection
model should be used to determine the locations of cross-docks. Build the decision model by defining
the decision variables and parameters. Select 25 different provinces from Turkey and generate crossdocking data using actual distance values between provinces. Solve the problem with the help of the
excel solver for 4 different coverage distances (for example, 100, 150, 200, 250), and show and discuss
the results with the help of a graph.
B. Unit transportation costs from cross-docks to regions and establishment costs of cross-docks are
different and known. The money that can be spent on assigning a region as a cross-dock is also limited.
Cross-docks have limited capacities. Write the relevant decision model for the case where the maximum
number of cross-docking nodes is known. Define the parameters and decision variables you deem
necessary, and assign the numerical values of parameters. Parameters that exist in question (A) must be
used with their current values. The populations of provinces should be used as demands of nodes. Solve
the problem with the help of excel for 4 different coverage distances used in question (A) and for 4
different P values (maximum number of cross-docks), and show and discuss the results with the help of
a graph.
C. Suppose management wants to meet as many demands as possible in the regions. Define the
parameters and decision variables you deem necessary, and assign the numerical values of parameters
Parameters that exist in questions (A) and (B) should be used with their current values. Solve the
problem with the help of excel for 4 different coverage distances used in question (A) and for 4 different
P values (maximum number of cross-docks) used in question (B), and show and discuss the results with
the help of a graph.
D. Use the 10 nodes reduced version of the problem you generated above. Develop a vertex p-center
formulation of the problem. Solve it with the help of excel and report the solutions.

DECLARATION
We/I certify that this is entirely our/my own work, except where we/I have given
fully-documented references to the work of others, and that the material contained in
this assignment has not previously been submitted for assessment in any formal course
of study. We/I understand the definition and consequences of plagiarism.
Student Name: Signature:
The homework report (in word or pdif file) and all supplementary files (excel) MUST BE UPLOADED
TO MOODLE as a single zip or rar file by the due date and time. Use the following format for the
filename: “Your Name and Surname_StudentID_HW1” (Example: AyseYıldız_ 2005245100_HW1).