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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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Using New Thin-Film Techniques To Manage Thermal And Energy Problems In Embedded Designs |
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Product Design - Wednesday
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Monday, 14 May 2007 |
Solid-state cooling and power generation have long been sought after as a solution for challenging thermal-management and energy problems. Thus, to address some of these issues, thermoelectric modules have been available for decades. The core component of a thermoelectric module is a thermocouple, which consists of two dissimilar semiconductors (referred to as p-type and n-type to describe dissimilar electrical conduction mechanisms in the two materials) connected together by a metal plate....more  (0) Comments |
HIL Simulation Boosts Automotive Design Efficiency |
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Test & Measurement / Data Acquisition - Tuesday
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Monday, 14 May 2007 |
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Hardware-in-the-Loop simulation reduces development cost and increases the quality of a vehicle. The unit under test provides feedback for the simulation, and testing can take place early in the design cycle. Driven by governmental regulations and market demand for better fuel economy and greater performance, the design of modern automobiles and the process of developing them have changed. Pushed by these challenges, the automobile has evolved from a mostly mechanical-hydraulic system to include complex automotive electronics and software algorithms implemented on electronic control units (ECUs)....more (0) Comments |
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System Clock Generators: PLL Synthesizer Vs. Crystal Oscillator Clock |
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Product Design - Wednesday
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Monday, 14 May 2007 |
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Paul Shockman of ON Semiconductor answers the question, "Should the new circuit board design or redesign use several crystal oscillator (XO) modules or a phase locked loop (PLL) synthesizer as its system clock source?" Read on for an in-depth comparison. Should the new circuit board design or redesign use several crystal oscillator (XO) modules or a phase locked loop (PLL) synthesizer as its system clock source? Whether a system clock is a control board within a rack of boards (e.g. multiple line cards), a single board router with switches, a server farm or a site area network, clocks will certainly be required. Could a PLL synthesizer source save board space and lower cost?...more (0) Comments |
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Compression/Decompression Tradeoffs For Data Networking And Storage |
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Product Design - Wednesday
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Monday, 14 May 2007 |
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Several design trade-offs to exist when building a high performance lossless data compression engine. Each of these trade-offs can vary the gate area of the end design greatly and have significant impact on the overall efficiency of the compressor (compression ratio). Compression, as the name implies, squeezes or "compresses" the size of a file or data set. Compression techniques are used for voice, video, audio, text, and program data in hundreds of different applications and product types. Much of the compression and subsequent decompression processing performed in products today is accomplished by a CPU running any number of different algorithms that have been specifically designed to efficiently reduce the size of a file or data set....more (0) Comments |
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