A novel unsupervised deep learning model for global and local health condition assessment of structures

A micro-cracking monitoring and fracture evaluation method for crumb rubber concrete based on the acoustic emission technique was developed. The precursory micro-cracking activity and fracture beha...

Micro-cracking monitoring and fracture evaluation for crumb rubber concrete based on acoustic emission techniques:

Circular sensing networks for guided waves based structural health monitoring

Synthesis of Compositional Microprogram Control Unitsfor Programmable Devices

This article newly proposes the application of the stretching method, that is used in geophysics for detecting variations in the velocity with which waves propagate in the earth's crust from seismic noise recordings, in the context of vibration-based Structural Health Monitoring SHM of civil structures. The result is a computationally efficient long-term vibration-based SHM tool, that follows the current trend of using a very limited number of sensors permanently installed on site to measure operational structural responses for the purpose of damage detection. In the SHM setting, the proposed method aims at a direct identification of small permanent shifts in the natural frequencies of the structure in a changing environment, which is achieved by maximizing the correlation coefficient between a reference waveform, computed in a training reference period in which the structure is assumed to be undamaged, and a stretched version of the same waveform evaluated at the current time. The comparison is performed in the frequency domain and the waveform of interest is obtained from cross-correlations of the ambient vibration measurements. More specifically, in the case of multiple sensors, the waveform can be either the cross-power spectral density of the signals recorded by a pair of sensors, or the largest singular value of the spectral matrix of the measurements. It follows that the method can be regarded as an extension of the classic Frequency Domain Decomposition FDD. A key feature of the proposed stretching method is mitigating the effects of environmental fluctuations by time domain averaging of cross-correlations over a proper period of time, before taking their Fourier transform to estimate the spectral densities. Such a time domain averaging is carried out in a relatively long period of time for estimating the reference waveform, whereas it is carried out in a shorter time for estimating the current waveform. The main features of the proposed methodology are its very low sensitivity to environmental fluctuations, resulting in a quite short training period length, and its low computational cost, which could be compatible with a direct integration within smart sensors with embedded electronics. The performance of the method is illustrated in the case study of an Italian historical monumental bell tower that has been monitored by the authors for more than 1 year.

The Stretching Method for Vibration-Based Structural Health Monitoring of Civil Structures

This paper presents an efficient method for implementation of digital filters targeted FPGA architectures. The traditional approach is based on application of general purpose multipliers. However, performance of multipliers implemented in FPGA architectures does not allow to constructs high performance digital filters. In this paper application of distributed arithmetic is demonstrated. Since in this approach combinational LUT blocks replace general purpose multipliers, it is possible to construct digital filters of very high performance. However LUT blocks can be of considerable size thus advanced synthesis methods have to be used to map them efficiently into FPGA resources. In this paper and application of the functional decomposition based synthesis has been investigated. This method is recognised as the best synthesis method targeted FPGA architectures and allows significant improvements in digital filters implementation. The paper presents many examples confirming that decomposition allows reduction of logic cell utilisation of filter implementation based on distributed arithmetic concept with no performance degradation and even increasing it.

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Efficient Implementation of digital filters with use of advanced synthesis methods targeted FPGA architectures

The paper presents logic synthesis method targeted at FPGA architectures with specialized embedded memory blocks (EMBs). Existing methods do not ensure effective utilization of the possibilities provided by such modules. The problem of efficient mapping of combinational and sequential parts of design can be solved using decomposition algorithms. The main question of this paper is the application of decomposition based methods for efficient utilization of modern FPGAs. It will be shown that functional decomposition method allows for very flexible synthesis of the designed system onto heterogeneous structures of modern FPGAs composed of logic cells and EMBs. Finally we present results of the experiments, which evidently show, that the application of functional decomposition algorithms in the implementation of typical signal and information processing systems greatly influences the performance of resultant digital circuits.

5 Logic Synthesis Method of Digital Circuits Designed for Implementation with Embedded Memory Blocks of FPGAs

General functional decomposition has been gaining more and more importance in recent years. Though it is mainly perceived as a method of logic synthesis for the implementation of Boolean functions into FPGA-based architectures, it has found applications in many other fields of modern engineering and science. In this paper, an application of balanced functional decomposition in different tasks of modern digital designing is presented. The experimental results prove that functional decomposition as a method of synthesis can help implementing circuits in CPLD/FPGA architectures. It can also be efficiently used as a method for implementing FSMs in FPGAs with Embedded ROM Memory Blocks.

The Influence of Functional Decomposition on Modern Digital Design Process

This article presents an embedded signal processing subsystem constituting a part of a whole structural health monitoring system (SHM). Typical SHM system is responsible for elastic wave generation and sensing, signal acquisition, and signal processing. Signal processing subsystem was designed with the aim of localizing damage utilizing elastic wave propagation in the interrogated structure. The embedded signal processing subsystem is realized in a field programmable gate array chip, which also implements a damage localization algorithm designed for creating damage maps that can indicate elastic wave reflection sites within the investigated structure. Elastic waves are generated and received using a prototype electronic system developed specially for this purpose. Piezoelectric transducers are arranged in networks with different geometrical configurations (strip, cross, and square). Elastic waves are excited by a five-cycle tone burst signal with carrier frequency of 220 kHz. The investigated structure is a simple isotropic panel made out of aluminum alloy. First, dispersion curves are computed on the basis of registered elastic wave signals. These are subsequently used in the damage localization process. The damage localization process utilizes the base antisymmetric A0 mode. This article presents results of experimental verification of the developed damage localization algorithm as well as results of damage localization by the embedded subsystem.

Embedded Damage Localization Subsystem Based on Elastic Wave Propagation

With the evolution of programmable structures, that become more heterogeneous, the process of mapping a design into these structures becomes more and more complex. Modern FPGA chips are equipped with embedded memory blocks that can be used to increase the implementation quality of the design. The paper presents a logic synthesis method based on balanced decomposition that uses the concept of r-admissibility to efficiently utilize possibilities provided by memory blocks embedded in modern FPGA architectures. Results presented in this paper prove the effectiveness of proposed approach.

Paweł Tomaszewicz

Papers

Efficient Implementation of digital filters with use of advanced synthesis methods targeted FPGA architectures

5 Logic Synthesis Method of Digital Circuits Designed for Implementation with Embedded Memory Blocks of FPGAs

The Influence of Functional Decomposition on Modern Digital Design Process

Embedded Damage Localization Subsystem Based on Elastic Wave Propagation

Logic synthesis strategy for FPGAs with embedded memory blocks