Multiple damage detection in complex bridges based on strain energy extracted from single point measurement

Strain Energy of the structure can be changed with the damage at the damage location.The accurate detection of the damage location using this index in a force system is dependent on the degree of accuracy in determining the structure deformation function before and after damage.The use of modal-based methods to identify damage in complex bridges is always associated with problems due to the need to consider the effects of higher modes and the adverse effct of operational conditions on the extraction of structural modal parameters.In this paper,the deformation of the structure was determined by the concept of influence line using the Betti-Maxwell theory.Then two damage detection indicators were developed based on strain energy variations.These indices were presented separately for bending and torsion changes.Finite element analysis of a five-span concrete curved bridge was done to validate the stated methods.Damage was simulated by decreasing stiffness at different sections of the deck.The response regarding displacement ofa point on the deck was measured along each span by passing a moving load on the bridge at very low speeds.Indicators of the strain energy extracted from displacement influence line and the strain energy extracted from the rotational displacement influence line(SERIL)were calculated for the studied bridge.The results show that the proposed methods have well identified the location of the damage by significantly reducing the number of sensors required to record the response.Also,the location of symmetric damages is detected with high resolution using SERIL.

A low-power and low-energy flexible GF(p) elliptic-curve cryptography processor

We investigate the use of two integer inversion algorithms,a modified Montgomery modulo inverse and a Fermat's Little Theorem based inversion,in a prime-field affine-coordinate elliptic-curve crypto-processor.To perform this,we present a low-power/energy GF(p) affine-coordinate elliptic-curve cryptography(ECC) processor design with a simplified architecture and complete flexibility in terms of the field and curve parameters.The design can use either of the inversion algorithms.Based on the implementations of this design for 168-,192-,and 224-bit prime fields using a standard 0.13 μm CMOS technology,we compare the efficiency of the algorithms in terms of power/energy consumption,area,and calculation time.The results show that while the Fermat's theorem approach is not appropriate for the affine-coordinate ECC processors due to its long computation time,the Montgomery modulo inverse algorithm is a good candidate for low-energy implementations.The results also show that the 168-bit ECC processor based on the Montgomery modulo inverse completes one scalar multiplication in only 0.4 s at a 1 MHz clock frequency consuming only 12.92 μJ,which is lower than the reported values for similar designs.