A full-range (360°) damage detection is necessary for structural health monitoring of large plate-like structures. However, the linear arrays are mainly limited by the range of damage detection, which is maximum up to 180°. Moreover the detection accuracy is also very poor at angles close to 0° and 180°. In order to solve this problem, a novel damage detection and localization method is presented in this paper. The proposed method combines the image enhancement technology and the cruciform piezoelectric phased array to improve the performance of the linear array based system. In addition to the implementation of cruciform phased array, a new image enhancement algorithm is proposed with an aim to deal with the problem of phantom image emerging in the opposite side of the original image. The results of the experiments conducted on aluminum plate and epoxy composite laminate plate show that the proposed method can effectively solve the limitations of the linear sensor array, and accurately detect single or multiple damages in full angle mode.
We present a system-on-chip (SOC) testing approach that integrates test data compression, test-access mechanism/test wrapper design, and test scheduling. An efficient linear feedback shift register (LFSR) reseeding technique is used as the compression engine. All cores on the SOC share a single on-chip LFSR. At any clock cycle, one or more cores can simultaneously receive data from the LFSR. Seeds for the LFSR are computed from the care bits for the test cubes for multiple cores. We also propose a scan-slice-based scheduling algorithm that attempts to maximize the number of care bits the LFSR can produce at each clock cycle, such that the overall test application time (TAT) is minimized. This scheduling method is static in nature because it requires predetermined test cubes. We also present a dynamic scheduling method that performs test compression during test generation. Experimental results for International Symposium on Circuits and Systems and International Workshop on Logic and Synthesis benchmark circuits, as well as industrial circuits, show that optimum TAT, which is determined by the largest core, can often be achieved by the static method. If structural information is available for the cores, the dynamic method is more flexible, particularly since the performance of the static compression method depends on the nature of the predetermined test cubes.
In this article, an introduction is pr esented about the energy harvesting technologies that have potential for powering nanosystems. Our discussion mainly focuses on the approaches other than the well-known solar cell and thermoelectrics. We mainly introduce the piezoelectric nanogenerators developed using aligned ZnO nanowire arrays. This is a potential technology for converting mechanical movement energy (such as body movement, muscle stretching, blood pressure), vibration energy (such as acoustic/ultrasonic wave), and hydraulic energy (such as fl of body fl uid, blood fl ow, contraction of blood vessel, dynamic fl uid in nature) into electric energy for self-powered nanosystems.
