Date: Dec 03, 2010 Author: Erich Schwartzel Source: Pittsburg Post Gazette (
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It takes months of gradual weakening for a mine roof to collapse in an instant. A Squirrel Hill engineer is working to track those several months and predict the breaking point.
Zvi "Steve" Meiksin has set up shop on Murray Avenue with Alertek LLC, a company that has designed sensors the size of Bubble Yum gum that have already foretold a roof collapse four hours before the dirt fell.
"We're monitoring the process of a structure's weakening," Dr. Meiksin said.
Since, in the case of a coal mine, that "structure" is an unsettled planet Earth -- and electronic equipment requires cords that don't play well with methane -- he has opted for a different unit of measurement to track the problem: sound.
Alertek is part of a growing community of companies looking to replace the infrastructure inspection tools of yesterday -- two eyes and a clipboard -- with high-tech devices that painlessly assess a project's condition with infrared, ultrasound or acoustic readings. To predict a collapse, Dr. Meiksin's technology places sensors on the bottom of 30-foot bolts shoved up the mine roof and reads the noises that rumble when the earth shifts bit by bit.
"It's like trying to find cancer at an earlier stage," said Piervincenzo Rizzo, assistant professor of civil and environmental engineering at the University of Pittsburgh.
Assessing infrastructure condition in a noninvasive way has become more popular in the aftermath of accidents like the rush-hour August 2007 collapse of the Interstate-35W bridge in Minneapolis, said Dr. Rizzo.
Government research on acoustic detection began more than 20 years ago but it mostly focused on technology that could hear the sounds but not analyze them, said Fred Blosser, public affairs officer for the National Institute of Occupational Safety and Health.
"It wasn't really directed toward trying to use sensors to identify sounds that might predict a collapse," he said.
Dr. Meiksin said Alertek technology could eventually predict a collapse one full day beforehand. The clues are in the long, skinny metal rods that act as roof supports.
When he started the company in 2006, he knew his technology couldn't alter or interfere with current mining procedures. So he focused on the iron bolts that are pushed through the mine roof for stabilization.
The bolts measure between 4 feet and 30 feet, and are placed about 4 feet apart. The bolts are shoved through shale, sand and coal but leave a small portion protruding from the roof, like the head of a nail in the wall.
The rectangular sensor is placed on the protrusion and can read acoustic emissions that travel down the bolt.
As the Earth shifts, it emits high-frequency noise that can be picked up by the bolts. The sounds read between 100 kilohertz and 2 megahertz -- a range usually only heard by dogs with hearing aids.
Acoustic readings work best for mines because they don't come loaded with electronics that can spark the explosive methane gas inside, said Dr. Rizzo.
Above ground, a computer program tracks the acoustic emissions and monitors the sounds for telltale signs of stress. Together, the readings form a "signature" that Dr. Meiksin has identified as a precursor to collapse. He keeps the exact details of the signature secret for competitive reasons.
In an induced collapse conducted earlier this year, Dr. Meiksin and his monitors detected the roof fall four hours beforehand. The technology has been approved by the Mine Safety and Health Administration.
The next generation of sensors to be used for commercial sale will be developed over the next two years and will cost several hundred thousand dollars to manufacture. It will be manufactured in Washington state and Virginia, with final testing and assembly at electronic labs in Pittsburgh.
But after the initial design is set and production grows, Dr. Meiksin thinks the sensors will cost about 20 cents each to make.
The sensors should retail between $2 and $4, and a major mine has more than 1 million bolts. Consol Energy and Alpha Natural Resources have agreed to place beta models of the second generation into their mines in anticipation of purchasing the first batch.
Alertek sensors will probably initially be seen at extrasensitive parts of the mine: near the conveyor belt that halts production if destroyed, or near cross sections with heavy foot traffic.
Until then, Dr. Meiksin will continue to test the technology at Pitt and in his office space, which is equal parts office, tool shed and bachelor pad.
There's a table with wood filler, hammers, screwdrivers, batteries of every possible size. There's a corner with computer terminals filled with data graphs. And there's a billiards table used after work with friends.
Dr. Meiksin had taught electrical engineering at the University of Pittsburgh for 30 years after coming to Carnegie Tech from Israel in 1952 -- all years spent above-ground until he consulted for mining companies on technology that tracked miners below ground. That was in 1978.
"They told me not to worry about technology for the next few years because soon they'd have robots doing the work," he said.
Soon after the Alertek founding in 2006, Dr. Meiksin secured $200,000 in funding from Innovation Works, the South Side-based nonprofit venture capital firm. An additional $25,000 in funds followed from the Greater Oakland Keystone Innovation Zone and another $100,000 from the National Institute for Occupational Safety and Health.
It's still just Dr. Meiksin in the office, but an engineer is coming on board in January.
Alertek technology looks promising to Dr. Rizzo -- "I wish I had had the idea," he said -- and could be one solution to a mine industry recently beset with a variety of crises in places like West Virginia and New Zealand.
Each type of infrastructure seems to have a corresponding method of noninvasive reading, he said. Ultrasound travels well through the natural gas pipelines because the pipe's geometry guides the waves, while infrared technology picks up the heat in transmission lines.
But when the time comes for expansion, Dr. Meiksin said his technology could be used to assess another Pittsburgh mainstay: the bridge.
