I mentioned the BAE shop in my last post. Here's a link! It details all the machines and capabilities of the lab.
BAE Machine Shop
Tuesday, May 26, 2009
Friday, May 22, 2009
Keys to the Lab
Today I got my keys to the lab where I'll be working! It's an old lab that's been out of use for quite a while, so there is a lot of cleanup to do. I'm not sure how involved I will be in that, but it might contribute to a slower start to the project than I hoped.
I took a tour of the Ag Shop. It's excellent ~ all kinds of tools and machines in there to create stuff with. Hopefully after next week I'll have access to some of the tools in order to make a (very simple) camera mount. And for items I don't know how to create, it sounds like the shop personnel will be able to make just about anything.
In the meantime, I'm working on a preliminary set of deadlines. Dr. Birgand will look it over and help set it up on a realistic time table.
I took a tour of the Ag Shop. It's excellent ~ all kinds of tools and machines in there to create stuff with. Hopefully after next week I'll have access to some of the tools in order to make a (very simple) camera mount. And for items I don't know how to create, it sounds like the shop personnel will be able to make just about anything.
In the meantime, I'm working on a preliminary set of deadlines. Dr. Birgand will look it over and help set it up on a realistic time table.
Tuesday, May 19, 2009
Gig
As of today I officially landed a part time gig to work as an undergraduate researcher with the NCSU BAE department this summer. (See archive posts for details on BAE.) I'll be working with Dr. Birgand and also with my friend Ken Chapman. We're working on some gadgetry to detect stream stage. More later!
Wednesday, May 13, 2009
Vacation Stream Gauge
In our travels through VA, WV, PA, OH, & IL, I have been seeing stream gauges all over the place!
Here's one on the Potomac River in Paw Paw, WV:
Monday, May 4, 2009
Hydrometry - Float Operated Gauges
Float gauges provide a mechanical means to measure water height.
Here are the basic components:
The line is attached to the float on one end and a counterweight on the other. It hangs on a pulley. The recorder keeps record of the pulley shaft rotation, which can be translated into water height. Recorders have traditionally been paper on a drum, but more are being converted to digital recorders that keep track of the pulley shaft rotation.
Typically, float gauges are installed in stilling wells, which help to produce stable measuring conditions.
There are several sources of error that must be considered when using the float operated gauges.
Systematic Effects:
1.) Float lag: The float tends to lag behind the true water level as the float rises and falls. This can be minimized by selecting an appropriate diameter float and sufficiently large float wheel.
2.) Intake pipe effects: The intake pipe (horizontal pipe in figure to the right) diameter can also introduce measurement error. A diameter that is too large can reduce the effectiveness of the stilling effect of the well by allowing water to surge in and out o
f the well. However, a too small diameter can introduce measurement lag because of head loss in the intake pipe.
3.) Chimney Effect: How far the intake pipe extends into the river cross section also impacts measurement due to chimney effect. This can produce a systematic underestimation of the water height.
Other Concerns:
4.) Counterweight: The counterweight location must be configured so the counterweight does not hit the float as it drops. Ideally, the counterweight is never submerged, as the effect of bouyancy on the counterweight will affect measurement.
5.) Tape/Wire: Kinks or twists in the line can cause measurement error. In addition, surges of water can potentially unseat the wire from the pulley.
Here are the basic components:
Float
Line (Tape, or Wire)
Pulley (Float wheel)
Counterweight
RecorderLine (Tape, or Wire)
Pulley (Float wheel)
Counterweight
The line is attached to the float on one end and a counterweight on the other. It hangs on a pulley. The recorder keeps record of the pulley shaft rotation, which can be translated into water height. Recorders have traditionally been paper on a drum, but more are being converted to digital recorders that keep track of the pulley shaft rotation.
Typically, float gauges are installed in stilling wells, which help to produce stable measuring conditions.
There are several sources of error that must be considered when using the float operated gauges.
Systematic Effects:
1.) Float lag: The float tends to lag behind the true water level as the float rises and falls. This can be minimized by selecting an appropriate diameter float and sufficiently large float wheel.
2.) Intake pipe effects: The intake pipe (horizontal pipe in figure to the right) diameter can also introduce measurement error. A diameter that is too large can reduce the effectiveness of the stilling effect of the well by allowing water to surge in and out o
f the well. However, a too small diameter can introduce measurement lag because of head loss in the intake pipe.3.) Chimney Effect: How far the intake pipe extends into the river cross section also impacts measurement due to chimney effect. This can produce a systematic underestimation of the water height.
Other Concerns:
4.) Counterweight: The counterweight location must be configured so the counterweight does not hit the float as it drops. Ideally, the counterweight is never submerged, as the effect of bouyancy on the counterweight will affect measurement.
5.) Tape/Wire: Kinks or twists in the line can cause measurement error. In addition, surges of water can potentially unseat the wire from the pulley.
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