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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
Redundant Power Techniques Explained |
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Product Design - Wednesday
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Friday, 11 May 2007 |
Find out which redundant power technique will work best for you. Redundant power is a critical component in high availability systems. In the simplest solution, two power supplies can drive a load through diodes to OR their outputs together. In this way, the power supplies can either share the load or have one active and the other in standby. A field effect transistor (FET) ORing controller is a more practical solution because it avoids the diode voltage drop, power loss and heat dissipation. More creative and economical systems can be configured with the low voltage loss MOSFET. Examples of redundant power supply configurations for server applications are discussed....more  (0) Comments |
How To Test The Interconnections Between FPGAs On A High-Density FPGA-Based Board |
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Test & Measurement / Data Acquisition - Tuesday
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Friday, 11 May 2007 |
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This article describes a simple, effective, and generic solution to check signal connectivity between FPGAs on a high density prototyping board with multiple FPGAs and hundreds of signals. High-density FPGA-based boards are widely being used for logic development and verification before taping out the actual IC. On a high-density FPGA-based board where multiple FPGAs are interconnected with hundreds of signals, checking and validating the interconnections between the FPGAs becomes a very challenging task. This article describes how challenging the problem is and also suggests a simple, effective, and generic solution to check the signal connectivity between the FPGAs. The method also helps the designer to identify and locate faults, if any, on the board which otherwise would have been a very cumbersome task. This article also proposes a method to efficiently generate the test code, most of which could be automated....more (0) Comments |
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How To Choose An RTOS For Your FPGA And ASIC Designs |
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Product Design - Wednesday
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Friday, 11 May 2007 |
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As an alternative to purchasing an off-the-shelf RTOS or writing your own, a new software synthesis technique called RTOS synthesis may be of interest for certain applications. This article examines different options for putting a real-time operating system (RTOS) on a system on a chip (SoC).If you purchase one, what is available and what are the tradeoffs? If you write your own, which issues will you need to take into account? If you synthesize one, what tools are available and how do they work?...more (0) Comments |
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