ISE 303 Operations Research 1 Exam 2 Sample

  1. Because of the rise in the number of accidents at different intersections in the city, The Khobar Traffic Department will install cameras to monitor the traffic and issue electronic tickets for traffic light violators. The map of Khobar is shown below and the dangerous intersections are indicated with dark small circles.

    Khobar, Saudi Arabia

    The cameras get their power from solar cells, by converting sun light to electricity. Images captured by the cameras are transmitted through radio waves, where the energy required to send images is proportional to the distance.

    The equivalent network with the distances in km is shown below:

    camera network

    Construct the minimum energy network of cameras by applying the minimum spanning tree algorithm.

  2. Zarief is a website design and search-engine-optimization solution based company, with sole emphasis on providing professional and quality web design, SEO consultancy, graphics design, and multimedia solutions. The development of a website requires the use of many graphics and html code generation software packages, and the time needed to develop a website would be influenced by the sequence by which these software packages will be used. Zarief is going to develop a website for the National Hajj Department, Ministry of Hajj, that will facilitate the national hajj seekers to get permits and pay fees. The network below shows the different ways the website can be developed, where each arc represents the time in days to develop a component of the website using a particular software package.

    website construction network

    Node 1 represents the start of the website development and node 7 represents the completion of the website. Zarief wants to determine the sequence of software packages that will minimize the time to develop the website. Use Dijkstra algorithm to solve the problem and indicate the number of days required to complete the site development.

  3. In SABB, King Abdul Azziz St. branch, customers arrive to the teller windows according to a Poisson process with a rate of 20 customers per hour. Customers of this SABB branch are usually managers, who expect to get service fast. When the arriving customer finds 3 customers or less in the bank, he is going to proceed to seek service. When the number of customers in the bank is between four and seven, there is a probability of 0.5 that he is going to leave without getting the service. If the number of customers is between eight and eleven, the probability he is going to seek service is only 0.2. The arriving customer is going to leave un-serviced if the number of customers is twelve or more.

    The management of the branch has given their tellers training on how to respond to high service volume. Tellers are able to adjust their service rate as the number of customers increases. In a specific day, there is only one teller and the service rate is exponential with a mean of 10 minutes. Because of the training he has been given, the average service time is 10 minutes if there is only one customer in the bank. The average service time is cut by half, i.e. 5 minutes, if there are two customers in the bank. The average service time is 10/3 if there are three customers in the bank, and so on.

    1. What is the effective arrival rate?
    2. What is the departure rate?
  4. Customers arrive to Dhahran Oil Change, where the inter-arrival times have an exponential distribution with a rate of one customer every 20 minutes. The time it takes to change the oil is exponentially distributed with a mean time of 18 minutes. When customers arrive to the oil change and find 9 cars waiting, they leave. There is only one worker, and he can only handle one car at a time. The owner of the oil change has determined that parking spaces are needed for the waiting customers. In order to keep the cost of parking area construction reasonable, the parking spaces that will be constructed will be equal to the expected number of waiting cars. How many parking spaces have to be constructed?

    Use the appropriate method to find the best assignment and calculate the corresponding total cost.

Dr Muhammad Al-Salamah

2008

Industrial Engineering

King Fahd University of Petroleum and Minerals