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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
How To Build Ultra-Fast Floating-Point FFTs In FPGAs |
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Product Design - Wednesday
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Monday, 14 May 2007 |
Engineers targeting DSP to FPGAs have traditionally used fixed-point arithmetic, mainly because of the high cost associated with implementing floating-point arithmetic. That cost comes in the form of increased circuit complexity and often degraded maximum clock performance. Certain applications demand the dynamic range offered by floating-point hardware but require speeds and circuit sizes usually associated with fixed-point hardware. The fast Fourier transform (FFT) is one DSP building block that frequently requires floating-point dynamic range and high speed. A textbook construction of a pipelined floating-point FFT engine capable of continuous input entails dozens of floating-point adders and multipliers. The complexity of these circuits quickly exceeds the resources available on a single FPGA. We fit the FFT design into a single FPGA without sacrificing speed or floating-point performance by using an alternative FFT algorithm and a hybrid of fixed- and floating-point hardware. The resulting design has IEEE single-precision floating-point inputs and outputs that match the precision obtained with more conventional designs, yet is capable of as much as 1.2 gigasamples-per-second continuous data throughput and fits into one Xilinx Virtex-4 XC4VSX55 FPGA....more  (0) Comments |
Safety First -- Why All Lithium Batteries Are Not The Same |
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Product Design - Wednesday
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Monday, 14 May 2007 |
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Lithium ion batteries have no memory effect and significantly better energy density than other types of batteries - but are they safe? We've all seen pictures of the infamous exploding laptop, and heard about or been affected by the massive, unprecedented recall of lithium-ion batteries. In August of 2006, Dell recalled 4.1 million notebook lithium-ion batteries, and Apple Computer recalled 1.8 million batteries. A month later, Panasonic recalled 6,000 batteries. As we've seen with this substantial recall, current lithium ion packs have one significant drawback: safety....more (0) Comments |
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IR Introduces 200V ICs For Low-Voltage Motor Drive Applications |
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Product Showcase - Friday
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Monday, 14 May 2007 |
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International Rectifier (IR) introduced a series of 200V ICs for low- and mid-voltage motor drive applications including power tools, low-voltage servo drives, electric garden equipment, and electric vehicles such as cranes, golf carts, and scooters. The IRS200x family of half-bridge, high-side and low-side driver ICs is tailored for low-voltage (24V, 36V, and 48V) and mid-voltage (60V, 80V and 100V) motor drive applications including both three-phase inverter and half-bridge. Under-voltage lockout (UVLO) protection is a standard feature provided across the family while the IRS2003 and IRS2004 also include deadtime protection. In addition, the IRS2004 features a shutdown input pin. These 200V ICs feature low quiescent current that enables a low-cost bootstrap power supply for the high-side circuitry, eliminating the need for large and expensive auxiliary power supplies that discrete optocoupler- or transformer-based designs typically require, suiting them for low-voltage applications that require a small footprint....more (0) Comments |
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