Structures in Other Domains The methodology of structural analysis discussed in this article has been applied beyond the narrow realm of natural language syntax that we have discussed in this article. Within the study of language, similar methods of analysis have been pervasively applied to the study of sounds (phonology), words (morphology), and meanings (semantics), yielding a range of of abstract structural representations whose properties bear considerable explanatory burden. There are a wealth of cases in each of these domains analogous to those discussed here, though space prevents us from going in these (see Akmajian, Demers, Farmer and Harnish 1995 for a traditional overview, and Jackendo 1994 for one more focused on connections with cognitive science). Additionally, these representations have shed substantial light on the processes of language acquisition and language change. It has been found that variation in the types of sentences that are used, whether during the course of children's acquisition of their native languages or in the centuries-long periods of linguistic change, are best characterized not as super cial and haphazard alterations, but rather in terms of parametric modi cations to the fundamental underlying grammatical rules and constraints. Moving outside the domain of language, one application of these same methods has been in the study of music cognition. Just as the representations of linguistic theory arise out of an attempt to model speakers' intuitions about well-formedness and possible meanings of the sentences of their

Structural analysis

In recent years, the range of sensing technologies has expanded rapidly, whereas sensor devices have become cheaper. This has led to a rapid expansion in condition monitoring of systems, structures, vehicles, and machinery using sensors. Key factors are the recent advances in networking technologies such as wireless communication and mobile ad hoc networking coupled with the technology to integrate devices. Wireless sensor networks (WSNs) can be used for monitoring the railway infrastructure such as bridges, rail tracks, track beds, and track equipment along with vehicle health monitoring such as chassis, bogies, wheels, and wagons. Condition monitoring reduces human inspection requirements through automated monitoring, reduces maintenance through detecting faults before they escalate, and improves safety and reliability. This is vital for the development, upgrading, and expansion of railway networks. This paper surveys these wireless sensors network technology for monitoring in the railway industry for analyzing systems, structures, vehicles, and machinery. This paper focuses on practical engineering solutions, principally, which sensor devices are used and what they are used for; and the identification of sensor configurations and network topologies. It identifies their respective motivations and distinguishes their advantages and disadvantages in a comparative review.

/pdf/wireless-sensor-networks-for-condition-monitoring-in-the-2he64b3jue.pdf

Wireless Sensor Networks for Condition Monitoring in the Railway Industry: A Survey

Active infrared thermography is a fast and accurate non-destructive evaluation technique that is of particular relevance to the aerospace industry for the inspection of aircraft and helicopters’ primary and secondary structures, aero-engine parts, spacecraft components and its subsystems. This review provides an exhaustive summary of most recent active thermographic methods used for aerospace applications according to their physical principle and thermal excitation sources. Besides traditional optically stimulated thermography, which uses external optical radiation such as flashes, heaters and laser systems, novel hybrid thermographic techniques are also investigated. These include ultrasonic stimulated thermography, which uses ultrasonic waves and the local damage resonance effect to enhance the reliability and sensitivity to micro-cracks, eddy current stimulated thermography, which uses cost-effective eddy current excitation to generate induction heating, and microwave thermography, which uses electromagnetic radiation at the microwave frequency bands to provide rapid detection of cracks and delamination. All these techniques are here analysed and numerous examples are provided for different damage scenarios and aerospace components in order to identify the strength and limitations of each thermographic technique. Moreover, alternative strategies to current external thermal excitation sources, here named as material-based thermography methods, are examined in this paper. These novel thermographic techniques rely on thermoresistive internal heating and offer a fast, low power, accurate and reliable assessment of damage in aerospace composites.

/pdf/recent-advances-in-active-infrared-thermography-for-non-3gr3hukcqv.pdf

Recent Advances in Active Infrared Thermography for Non-Destructive Testing of Aerospace Components.

http://web.mae.ufl.edu/nkim/Papers/paper19.pdf

Review of options for structural design sensitivity analysis. Part 1: Linear systems

Design optimization of regular hexagonal thin-walled columns with crashworthiness criteria

For 20 years of development, the virtual distortion method (VDM) has proved to be a versatile reanalysis tool in various applications, including structures and truss-like systems. This article presents a summary of principal achievements, demonstrating the capabilities of the VDM both in statics and dynamics, in linear and nonlinear analysis. The major advantage of VDM is its exactness and no need for matrix inversion in the reanalysis algorithm. The influence matrix—numerical core of the VDM—contains the whole mechanical knowledge about a structure, by looking at all global responses due to local disturbances. The strength of the method is demonstrated for truss structures.

https://smart.ippt.gov.pl/dok/artykuly/2008%20The%20virtual%20distortion%20method%20-%20a%20versatile%20reanalysis%20tool%20for%20structures%20and%20systems.pdf

The virtual distortion method—a versatile reanalysis tool for structures and systems

The Digital Image Correlation (DIC) technique enables full field, noncontact measurements of displacements and strains of a wide variety of objects. An adaptation of the DIC technique for monitoring of civil-engineering structures is presented in the paper. A general concept of the complex, automatic monitoring system, in which the DIC sensor plays an important role is described. Some new software features, which aim to facilitate outdoor measurements and speed up the correlation analysis, is also introduced. As an example of application, measurements of a railway bridge in Nieporet (Poland) are presented. The experimental results are compared with displacements of a FEM model of the bridge.

/pdf/monitoring-of-civil-engineering-structures-using-digital-17bllwrs6u.pdf

Monitoring of civil engineering structures using Digital Image Correlation technique

SUMMARY

This paper presents an in situ implementation of the weigh-in-motion (WIM) concept for the railway transport. The presented WIM system constitutes a part of a larger structural health monitoring system dedicated to railway bridges. The identification of train load acting on a bridge is necessary for performing subsequent identification of damage in the analyzed structure. Some existing WIM methods in the railway applications have been reviewed. The authors' implementation based on piezoelectric sensors has been described in detail. Hardware development of the WIM system, including wireless data transfer to a remote analysis centre, has been outlined. Results from measurement sessions carried out in situ have been presented and successfully verified by a numerical model of rail–sleeper–ground interaction. Copyright © 2010 John Wiley & Sons, Ltd.

Piezo-based weigh-in-motion system for the railway transport

The effect of selected parameters on ship collision results by dynamic FE simulations

A hybrid reasoning system is developed for damage assessment of structures. The system combines the use of a model of the structure with a knowledge-based reasoning scheme to evaluate if damage is present, its severity (severity and dimension) and its location. Using a given model (or several models), the structural dynamic responses to given excitations are simulated in the presence of different forms of damage. In a 'learning mode' an initial casebase is created with the principal features of these damage responses. When the system is working in its operating mode, data acquired by sensors are used to perform a diagnosis by analogy with the cases stored in the casebase, reusing and adapting old situations. Whenever a new situation is detected, it is retained in the casebase to update the available information. This paper describes the methodology and how the system is built and tuned to be ready for operation. This is illustrated by a numerical example of a cantilever truss structure and tested numerically and experimentally with a beam structure. Conclusions are presented with the emphasis on the advantages of using knowledge-based systems for structural assessment.

http://smart.ippt.gov.pl/dok/artykuly/2005%20A%20hybrid%20approach%20of%20knowledge-based%20reasoning%20for%20structural%20assessment.pdf

Przemysław Kołakowski

Papers

The virtual distortion method—a versatile reanalysis tool for structures and systems

Monitoring of civil engineering structures using Digital Image Correlation technique

Piezo-based weigh-in-motion system for the railway transport

The effect of selected parameters on ship collision results by dynamic FE simulations

A hybrid approach of knowledge-based reasoning for structural assessment