Thursday, July 05, 2007

Scheduling Dell

The recent issue of Interfaces has an interesting article about production scheduling at one of Dell's computer assembly plants. The article, which focuses on kitting (collecting the parts needed for each customer order), not only presents the mathematical formulation of the problem but also discusses the production scheduling process. I found it interesting that changing the objective function was a difficult culture change for the Dell employees. They were used to balancing the load, making sure that different kitting lines had approximately equal workloads. The new management objective was to reduce the number of setups, which was set to increase dramatically due to other changes in their operations. So showing the employees how the new algorithms would not impact load balancing was key to getting them to accept the new procedures.

If I ever get around to a second edition of the Handbook of Production Scheduling, this would be a good story to include.

Monday, July 02, 2007

Home Again

After the frustration of Saturday afternoon, Sunday brought better weather and some good luck.

The standby list for the 10:30 flight was long, but everyone on the list made it. I got a bulkhead seat (in the middle) and enjoyed having the extra leg room. The flight was trouble-free, and I chatted with the young soldier who had the window seat. He was headed home for two weeks of leave, and he was planning to surprise his family, who lives on Kent Island, Maryland. We talked about Iraq, where he's spent seven months, which put things into perspective. No matter how long and tiring my trip was, there are many others with longer ones to places that were much less pleasant.

We had a nice view of the Chesapeake Bay, including Kent Island and Annapolis, as we approached BWI, and he was thrilled to see it from that perspective for the first time. We got into the gate a bit early, and I quickly walked up the C concourse to find Laury and Colleen waiting for me!

We decided that I would get some lunch while we waited for the bags to arrive. Back in baggage claim, we watched and searched - Delta had hundreds of bags down there, and, just as I was waiting to file a claim for the garment bag, it appeared on the belt! Colleen and I chased it down, and then we were headed home, and my odyssey was over.

Sunday Morning in Atlanta

[Written Sunday, July 1, 2007.]

It is amazing how busy an airport is early on a Sunday morning. The hotel breakfast room was quiet, and there was little traffic, but the lines for check-in and for security were very long (though moving quickly). Of course, I don't have any bag to check (it should be in Baltimore by now), and a nice lady helped me get onto the standby list for the next flight to Baltimore.

So now I wait - more waiting! - but I had a good rest and am back on relatively familiar ground.

Saturday Night in Atlanta

[Written Saturday, June 30, 2007.]

The Atlanta airport this evening is busy and noisy and frustrating. I was very glad to be on the ground, but there was little other good news. Our plane had to wait on the tarmac to get to a gate. Then there was congestion in the baggage unloading area, so it took awhile for our bags to appear, at which point I was sure that I was going to miss my flight. Then a long line that moved quickly through customs, and the line for security (don't know why we're going through security - we did so in Athens - but I suppose not all arriving international passengers have been through appropriate security). Then it was a dash to gate E3 to make sure I could get on the Baltimore flight, which had been moved next door to E5, which was still boarding a flight to Dallas-Fort Worth. Our flight was at 8:05; at 8:20 they moved us from E5 to E18.

Our departure time kept slipping, and then, just as they said that they were beginning to board, I heard some thunder. A look out the window confirmed that a thunderstorm had arrived. Soon they announced that the ramp was closed (I had a similar long delay at Tampa a couple years ago). At this point I surrendered and called Delta to get a flight for Sunday afternoon. Between the lady on the phone and the gate agent, they put me on a flight for 2:30 Sunday, and I went in search of a hotel room. I stopped at the airport information counter in the main terminal. The nice guys there were still at work (it was now just after 10 PM), and they pointed me to the hotel courtesy phones and the hotel shuttles. I called the good old Hampton Inn, got a reservation, and went out to the shuttles in the pouring rain. The Hampton shuttle was just pulling out, but I waved him down, and we got to the hotel safely.

Saturday Morning in Athens

[Written Saturday June 30, 2007.]

The weather in Athens was still warm but the heat wave was over. Saturday morning was sunny with a bit of a breeze. I went to see Lycabettis Hill, which is near the hotel. I was considering the cable car (funicular), but I was there at 8:30-ish and that didn't open until 9. So I walked down the block and found the path that heads up the hill, which is mostly covered in small pine trees, cactus, and other shrubs. Halfway up the hill I came to an abandoned cafe and some overlooks with tremendous views of Athens, including the Parthenon - I was glad that I had deleted some photos on the camera to make room for more. Athens usually has bad smog, but there was none to obscure the view, fortunately.

Then it was back downhill to the hotel, where I checked out and took a cab to the airport. The cab driver took the secondary roads instead of the expressway, so I got to see some of development that are converting olive groves into suburbs and retailers. It looked similar to the stuff one would see on the outskirts of any city, though there were no shopping centers, just individual retailers alongside the road. Delta had two long check-in lines, one for each of its flights (mine to Atlanta, the other to JFK). Ours was long enough for me to start a time study to predict my completion time. They served, on average, one person a minute, and my total wait was 60 minutes long.

We departed on time, but the flight was very long - over 11 hours, and we had three movies: The Astronaut Farmer (good), Wild Hogs (didn't watch it), and Bridge to Terebithia (very good). I didn't sleep at all; when not watching a movie or eating, I listened to the in-flight audio (especially the country and 80's pop channels - the latter played Africa by Toto and American Girl by Tom Petty) or my book on CD (The Odyssey). I won't finish either of the Homeric epics - reading those needs an environment with fewer distractions, and I still have Dante at home to read.

Starting for Home

[Written on Friday June 29, 2007.]

Here is a photo of Minis and his students, taken in the lab just after my presentation:

The Chios airport is very small (no taxiway, one runway, one baggage claim belt, two gates, three check-in stations) but is, for better or worse, full of the same processes as any other airport: ticketing, check-in, bag check, security, baggage claim, and waiting. My Olympic Airlines flight is delayed because the incoming plane from Athens was not on time. I wonder if it is the same plane going back and forth all day long; as soon as it gets behind, all of its remaining flights are delayed. We're beginning to board (the gate agent is checking boarding passes) at 6:15 right now for a 5:45 flight.

It is nice to be taking the first few steps towards home; even getting in the car to leave the lab was a sign of progress towards home. I'm reminded of some song (from the Hobbit or the Lord of the Rings) about the road that goes ever on, but now I'm headed home.

Got to Athens without any trouble, got my bags, and ate some dinner at the McDonald's - I had to have the McTost, which reminded me a bit of those flattened hamburgers that are sold at the Varsity. Took the Metro back to Megaro Moussikis and walked a few blocks to the hotel (the same one where I had stayed last weekend). Checked in and am going to bed.