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Time and frequency response of an avalanche quantum dot infrared photodetector (A-QDIP) operating at long infrared (IR) wavelengths is calculated and the effect of its structure on the dynamic behavior is studied. For this purpose, the rate equations of different regions are numerically solved considering the boundary conditions. Results show that detector with long multiplication region has a slower time response. Also frequency analysis predicts a 3-dB bandwidth above 100 GHz for a device with multiplication length of 200 nm. Gain bandwidth product (GBP) is calculated and a value of about 1000 GHz is obtained. Effect of charge layer doping on dynamic response of detector is also studied and results show that increase in doping improves the GBP while the bandwidth is reduced. We also study the effect of quantum dots of absorption region on frequency response of device and results show that longer electron relaxation time into quantum dot decreases the bandwidth of detector.

This chapter reviews and compares some of the most known methods of damage identification, in the frequency domain, which use operational deflection shapes (ODSs) built from the frequency response functions (FRFs). Two new methods of damage identification, in the time domain, using (ODSs) built from the time responses are also analyzed. To assess the performance of the different indicators, two numerical tests are undertaken with a finite element model (FEM) model, of a cantilever beam, to evaluate their detection and localizing ability.