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Sensors Provide Early Diagnosis Of Microcracks In Aircraft |
 Today's aircraft are in service virtually around the clock and must operate reliably and safely at all times. An active sensor system helps to detect concealed fatigue cracks in aircraft bodies, thus reducing maintenance times considerably.
If a tiny crack in the hull of an aircraft remains undetected for a long time, it can easily spread and put passengers’ lives at risk. Each component is therefore subject to international maintenance regulations: Aircraft bodies must be thoroughly inspected every 15 to 18 months, depending on the type of plane. This often requires the technicians to dismantle an aircraft’s interior lining – an expensive and time-consuming process involving several days of downtime in the hangar. Researchers at the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt are developing a sensor system that allows engineers to continuously monitor the condition of their aircraft and detect any damage at an early stage.
The system is based on piezoceramic sensors that are attached to the aircraft body in a network pattern. What is special about these sensors is that they start to oscillate when a voltage is applied to them – and when they are subjected to pressure, they generate voltage. The scientists make use of both effects: While the piezo foils cause part of the hull to oscillate, the others measure the component’s response to this stimulation. “We investigated the oscillation behavior of damaged struts and rivets in an aircraft body and compared it with that of intact parts,” explains LBF project manager Dirk Mayer. “If a component is defective, it oscillates at a different frequency from one that is intact when stimulated by the piezoceramics – just as a cracked glass sounds different from an undamaged one when you tap it with your fingernail.” In this way, the researchers can accurately track down faults and monitor their development – be it fatigue cracks in the hull and wings, or rivets and other joining parts coming loose. This form of observation is also referred to as ‘structural health monitoring’ (SHM).
“With the help of this system, any damage behind the lining or in difficult-to-reach places can be identified quickly and easily, thus reducing maintenance times and inspection costs,” says Mayer. The researchers have already performed tests on a hull component in the laboratory, and are now implementing the new technology with standardized piezo and electronic components. The system will then also be suitable for use in vehicle manufacture or engine and plant construction.
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Dear Editor,
I hope you can help me or at least point me in the right direction. My neighbor just put up a huge CB Radio antennea, the thing is higher that the roof of his home, the problem is, now I have interference through our television set speakers. We can hear him speaking although it is not too clear. How can I fix the problem so that we can watch t.v. without hearing this noise? Any help you can give me would be greatly appreciated.
Sincerly,
Donna R.
Dear Donna,
If your neighbor's transmissions are interfering with your TV, the best thing for you to do is complain to the Federal Communications Commission. The FCC investigates cases of interference and they will determine if your neighbor's transmissions contain out-of-band signals. You might also try talking to your neighbor. If his antenna is for amateur radio rather than Citizens Band, "ham" radio operators have a policy of supplying a free filter for your TV in such cases.
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ElectronicDesignNet News
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We scan the wires, web sites, blogs and news media for the most interesting and relevant information, then summarize it for you in a convenient format, organized by topic areas during the week:
You can stay on top of things without wasting your precious time sifting through lots of noise. Subscribe to our digest and receive it in your eMail, or come to our site and read it in your web browser. Digest eMail subscriptions can be managed on the Newsletters tab of the "My Settings - Edit Profile" page once you register.
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A Primer On High-Side FET Load Switches |
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Components / Sensors - Thursday
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Monday, 07 May 2007 |
Understand the operation, functions, and key parameters of high-side FET load switches, as well as the similarities and differences between N-channel and P-channel devices. High-side load switches and their operations continue to be popular choices for many engineers and designers, for applications including battery-powered portable devices such as feature-rich mobile handsets, mobile GPS equipment, and consumer entertainment gadgets. This article takes an easy-to-understand and non-mathematical approach to explain the various aspects MOSFET-based high-side load switches and discusses the various parameters that must be considered throughout the design and selection process....more  (0) Comments |
Force Crosstalk Compensation Using Matrix Methods |
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Product Design - Wednesday
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Monday, 07 May 2007 |
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In almost any force sensor application, forces other than the one(s) being measured will be present. These extraneous forces will invariably cause errors in the measured values through what is called crosstalk. Crosstalk is a phenomenon were the sensor reports an output value for a particular direction when the force that caused the output was in a different direction. Through the use of the mathematical technique described below, this crosstalk error can be all but eliminated....more (0) Comments |
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Design "Fuel Gauging" For Multi-Cell Li-Ion Battery Packs |
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Product Design - Wednesday
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Monday, 07 May 2007 |
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Here's help designing a solution that provides accurate battery capacity information for portable devices. Portable devices, such as laptop computers, cellular phones and media players, have an increasing demand for power as the trend for functionality integration and technology convergence continues. Li-Ion battery, the main rechargeable power source for these devices, is having a difficult time keeping up with the power requirement of portable devices. While seeking generational advancement in new power sources, system designers also want to fully exploit the offerings of existing battery technologies....more (0) Comments |
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A How To Tutorial On Logic Analyzer Basics For Digital Design |
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Test & Measurement / Data Acquisition - Tuesday
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Monday, 07 May 2007 |
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This tutorial provides an overview of logic analyzer basics; most logic analyzers are really two analyzers in one: a timing analyzer and a state analyzer. Let's assume that you need to simultaneously look at the inputs and outputs of a 16-bit counter to determine a timing error, but you have only a 2-channel scope – how do you look all of the required signals? Or let's suppose that you've just developed timing diagrams for a board full of digital circuitry. How do you verify them? What do you use to capture and analyze the signals on the board? Without the appropriate tool, solving these kinds of problems can be very time consuming. For the above problems, a logic analyzer is the best solution. This article provides a quick overview of logic analyzer basics and offers ideas as to what can be achieved using a logic analyzer....more (0) Comments |
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