Expert Systems for Human Materials and Automation Part 9 ppt

Expert System Development for Acoustic Analysis in Concrete Harbor NDT 231 The electronics industry has provided inspectors with equipment that is capable of detecting and recording the sonic wave signals that are produced by an impact. As a result, there are currently several commercially available products available for such signal acquisition. The most common devices for sonic data acquisition are the instrumented hammer and the smart hammer. The instrumented hammer was developed for the airline industry to be used in the detection of anomalies in airplane materials. It measures and records the force-time history and amplitude frequency of an impact via the use of an accelerometer embedded in the head of the hammer. The smart hammer was developed for the shipbuilding industry. This instrument measures and records the sonic response of an impact through a microphone. The microphone uses the sonic data, instead of the force data, to create an acoustic signal. Both impact-force data generators and impact-sound data generators have been proven to generate useful signals for non- destructive sonic testing. The information gained. Fig.6. illustrates the block diagram of proposed non destructive sonic testing system. Fig. 6. Schematic diagram showing how impact-echo of proposed system works 7.5.1 Acoustic sounding Acoustic sounding is used for surveying concrete structures to ascertain the presence of delaminations. Delaminations can be a result of poor concrete quality, debonding of overlays or applied composites, corrosion of reinforcement, freezing and thawing or global softening. The test procedures used for delineating delaminations through sounding include: coin tap, chain drag, hammer drag, and an electro-mechanical sounding device. The purpose of each test is to sonically detect deficiencies in the concrete. The American Society for Testing and Materials (ASTM) has created a standard, ASTM D 4580 – 86, which covers the evaluation of delaminations. The standard describes procedures for both automated and manual surveys of concrete. A major advantage to sonic testing is that it produces immediate results on near surface anomalies. The Expert Systems for Human, Materials and Automation 232 effectiveness of sonic testing relies heavily on the user's expertise in signal interpretation and consistency. Soundings are taken by striking the concrete surface to locate areas of internal voids or delamination of the concrete cover. Although the results are only qualitative in nature, the method is rapid and economical and enables an expeditious determination of the overall condition. The inspector’s ability to hear sound in water is reduced by waves, currents, and background noise. Soundings are the most elementary of NDT methods (Wu T et al 2000). 7.5.1.1 Impact hammer A standard impact hammer (ASTM C 805), modified for underwater use, can be used for rapid surveys of concrete surface hardness. The underwater readings, however, are generally higher than comparable data obtained in dry conditions. These higher readings could be eliminated by further redesigning of the Schmidt hammer for underwater use. Data also can be normalized to eliminate the effect of higher underwater readings. 7.5.1.2 Coin-tap test This important method of testing the concrete is one of the deepseated and most widely researched ways of sonic testing. The test procedure requires the inspector or operator to tap on the concrete sample with a small hammer, coin, or some other rigid object (impactor) while listening or recording the sound resulting from the impact. Areas of nondelaminated concrete will create a clear ringing sound upon impact while regions of delaminated, disbonded, or softened concrete will create a dull or hollow sound (Fig.7). This change in sonic characteristics is a direct result of a change in effective stiffness of the material. As a result, the force-time function of an impact and its resulting frequencies of an impact differ between areas of good and poor quality concrete (Cawley & Adams 1988) Fig. 7. Spectra of time histories for a typical tap test results 8. Spectru & cepstrum analysis The vibration spectrum can be expressed on a linear frequency scale with constant bandwidth. This type of spectrum provides fine resolution at higher frequencies but a poor resolution at lower frequencies. Whereas a constant percentage bandwidth analyzer uses Expert System Development for Acoustic Analysis in Concrete Harbor NDT 233 logarithmic frequency scale and cover three decades with equal resolution. It is for this reason that the best analysis method for the comparison of spectra and fault detection is the use of constant percentage bandwidth with a logarithmic frequency scale (Farid Uddin 2003). Cepstrum analysis is carried out to identify a series of harmonics or sidebands in the spectrum. Cepstrum may be considered to be the frequency analysis of frequency analysis. The power cepstrum is defined as: () () { } -1 pxx C τ = F lo g F f (1) Where f x (t) is the time signal and its Fourier transform is () xx Ff. Fig. 8. shows a spectrum from a concrete structure in its deteriorated condition. It contains several harmonics. It is not possible to detect from this spectrum that there are two series of harmonics indicating two different phenomena. Fig. 8. The spectrum from a concrete structure in its deteriorated condition Cepstrum of this spectrum is also give in the side. It may be seen that the cepstrum identifies these two families of harmonics (with a spacing of 48.5 Hz and 119.4 Hz respectively). Fig. 9 shows the edited spectrum such that frequencies below that of half of the impactor frequency are removed. The cepstrum of this spectrum is then calculated. The cepstrum does not show the 119.4 Hz component at all. It indicates that this component originates from the lower frequency range. The cepstrum does retain the 48.5 Hz component indicating its origin in the medium frequency range. It may thus be concluded that the impactor effect on the tested structure at 49.8 Hz may have an incipient fault while the recorded components at 119.4 Hz indicates delamination, voids or other fault. Expert Systems for Human, Materials and Automation 234 Fig. 9. Frequencies below that of half of the impactor frequency are removed. In this research the Acousto – Vibration (AV) technology utilized to detect defects, such as voids and mix separations in the constructed pats. 9. Conclusion The Reinforced Concrete Structure Diagnosis Expert System is implemented through this research work as a prototype rule based system using the Professional expert system shell. It is apparent that in the proposed method, the perfect undersea concrete structure should not produce vibration signals more than the normal value. This is never the case, for it is impossible to eliminate all asymmetries in the materials and geometry of the concrete and steel armor in the structure. It results from the measurements having been carried out that several predominant frequencies arise in the specimens under test. To extract knowledge from the expert the knowledge engineer must become familiar with problem of vibration and acoustic analysis. The rule base system is goal driven using backward chaining strategy to test the collected structure vibration and acoustic properties information is true. The case specific data plus the above information with the help of explanation subsystem, allows the program to explain its reasoning to the user and will provide the expert system shell requirements. Significant difference can exist between the Expert System Development for Acoustic Analysis in Concrete Harbor NDT 235 signals created by subsea concrete defects. The respective amplitudes of the mentioned signals may exceed each other in a different way in repeated measurements of the same specimen. This device serves as a base for development of expert system monitoring module. The change of reference signal with proposed expert system implies that something within the subsea concrete structure has altered and diagnosis is made. By integrating the different modules, the proposed system has the power to provide diagnosis of problems in reinforced concrete harbor structures. This can assist civil engineering trainees, inspectorate staff, professional engineers as well as their top harbor management personnel regarding the likely problems so that early action can be taken. The present work will be particularly of great assistance to new comers who are not familiar with the field and will facilitate them in gaining a better understanding of the causes of the problems and in making decisions about any necessary actions 10. References British Standards Institution, (1985) "BS 8110: Part 1, Structural Use of Concrete", ,London. British Standards Institution, (1991) "BS 5328: Parts 1 to 4, Specification of Concrete", London. Cawley, P. and Adams, R.D. (1988) 'The Mechanics of the Coin-Tap Method of Non- Destructive Testing', J. Sound and Vibration, Vol 122, pp.299-316 Dym, Clive L. and Levitt, Raymond E.,(1991)"Knowledge Based Systems in Engineering",McGraw-Hill, New York, 1991, pp. 15& 404 ISBN. O-O7-018563-8. Filippetti F., et al.(1992).Development of expert system knowledge base to on-line diagnosis of rotor electrical faults of induction motors. IEEE-Industry Applications Society Annual Meeting, Bologna, pp. 92-99 Farid Uddin A. K. M., Ohtsu M, Hossain K. M. A., and Lachemi M (2007).Simulation of reinforcement-corrosion-induced crack propagation in concrete by acoustic emission technique and boundary lement method analysis. Canadian J. of Civil Engineering, Oct , vol. 34, , no. 10, pp. 1197-1207 Graham-Jones, P. J., Mellor B. G. (1995) "Expert and knowledge-based systems in failure analysis" Engineering Failure Analysis, Volume 2, Issue 2, June, pp.137-149 Hughes, D.M. (1972) "Underwater inspection of offshore structructurs – method and results. Proc. Offshore Tech. Conf.,V.I, pp.541-546 Hedayati M. R. (2004).On-line condition monitoring of locomotives. Proceeding 7thRailway conf., Tehran, Iran. pp. 217-223 Hedayati M.R., (2009). Sub-sea fiber optic cable maintenance using a ROV-based flux leakage expert system. Journal of Artificial Life and Robotics 14(4):pp511-514 Korenska M, Chobola Z., Mikulková P., and Martinek J.(2003). On the application of impact- echo method to assess the quality of ceramic roofing tiles. IV. Conf. MATBUD, Krakow, pp. 239 – 244 Roddis, W. M. Kim, and Pasley, Gregory P., (1993) "Knowledge-Based Expert Systems in Concrete Materials: Uniting Specifications, Data, and Models," Presentation at the 1993 Fall Convention, American Concrete Institute Expert Systems for Human, Materials and Automation 236 Skala J. and Chobola Z (2005), “Frequency Inspection as a Tool to Assess the Armature Corrosion. Workshop NDT 2005 Non- Destructive Testing at Engineering, Brno,pp. 159-161 WU, T. T. et al., (2000).On the Study of Elastic Wave Scattering and Rayleigh Wave Velocity Measurement of Concrete with Steel Bar. vol. 33, UK: NDT & E International, pp. 401-407 Part 3 Automation & Control 0 Conceptual Model Development for a Knowledge Base of PID Controllers Tuning in Open Loop José Luis Calvo-Rolle 1 , Ramón Ferreiro García 1 , Antonio Couce Casanova 1 , Héctor Quintián-Pardo 1 and Héctor Alaiz-Moreton 2 1 University of Coruña 2 University of León Spain 1. Introduction In the area of control engineering work must be constant to obtain new methods of regulation, to alleviate the deficiencies in the already existing ones, or to find alternative improvements to the ones that were being used previously. This huge demand of control applications is due to the wide range of possibilities developed to this day. Regardless of this increasing rhythm of discovery of different possibilities, it has been impossible at this moment to oust relatively popular techniques, as can be the ’traditional’ PID control. Since the discovery of this type of regulators by Nicholas Minorsky (Mindell (2004) and Bennett (1984)) in 1922 to this day, many have been the works carried out about this controller. In this period of time there was an initial stage, in which the resolution of the problem was done analogically and in it the advances were not as notable as have been since the introduction of the computer, which permits to implement the known direct digital control structure Auslander et al. (1978), illustrated in figure 1. Since then, the regulators have passed from being implemented in an analogous way to develop its algorithm control digitally, by signal digital processors. As well as carrying out the classic PID control in digital form, its development based on computer allows adding features to the regulator that with difficulty could have been obtained analogically. Fig. 1. Structure of direct digital control 13 2 Will-be-set-by-IN-TECH It must be said there exist usual control techniques for the processes in any area, in which innovations have been introduced. But nevertheless, the vast majority of these techniques in their implementation employ PID traditional controllers, although in an improved way, increasing the percentage of use around 95% Astrom & Hagglund (2006). Its use is still very high due to various reasons like: robustness, reliability, relative simplicity, fault, etc. The great problem of the PID control is the adjustment of the parameters that it incorporates. Above all in its topology Astrom & Hagglund (2006) Feng & Tan (1998), as a consequence of the investigations carried out in the area, the contributions made by specialists have been many, existing among them many methods to obtain the parameters that define this regulator, achieved through different ways, and working conditions pertaining to the plant being controlled. It must be highlighted that the methods developed to obtain the terms which in occasions are empiric if they are always directed to optimise defined specifications; the negative thing is that frequently when some are improved others get worse. It is necessary to highlight that the empirical methods have been the first in to be discovered and normally they are the ones who are first learnt, in the training of technicians in this discipline. In this sense the parameters obtained in this manner through the application of formulas of different authors, are a starting point of adjustment of the regulator, being normally necessary to have to do fine adjustment. Regardless of what has been said, in practice there is a big variety of regulators working in the industry with an adjustment far from what can be considered optimum Astrom & Hagglund (2006). This fact is originated among other reasons due to a lack of adjustment techniques by the users. This fact creates the necessity to employ intelligent systems, due to the demand of a better performance and resolution of complex problems both for men as well as for the machines. Gradually the time restrictions imposed in the decision making are stronger and the knowledge has turned out to be an important strategic resource to help the people handling the information, with the complexity that this involves. In the industry world, intelligent systems are used in the optimization of processes and systems related with control, diagnosis and repair of problems. One of the techniques employed nowadays are knowledge based systems, which are one of the streams of artificial intelligence. The development of knowledge based systems is very useful for certain knowledge domains, and also indispensable in others. Some of the more important advantages that the knowledge based systems offer are the following: • Permanence: Unlike a human expert, a knowledge based system does not grow old, and so it does not suffer loss of faculties with the pass of time. • Duplication: Once a knowledge based system is programmed we can duplicate countless times, which reduces the costs. • Fast: A knowledge based system can obtain information from a data base and can make numeric calculations quicker than any human being. • Low cost: Although the initial cost can be high, thanks to the duplication capacity the final cost is low. • Dangerous environments: A knowledge based system can work in dangerous or harmful environments for the human being. • Reliability: A knowledge based system is not affected by external conditions, a human being yes (tiredness, pressure, etc). 240 Expert Systems for Human, Materials and Automation [...]... Hypertext knowledge base for the control theory, Automation and Remote Control 61(11): 192 8– 193 3 258 20 Expert Systems for Human, Materials and Automation Will-be-set-by-IN-TECH Feng, Y & Tan, K ( 199 8) Pideasytm and automated generation of optimal pid controllers, Third Asia-Pacific Conference on Control&Measurement, Aviation Industry Press, Dunhuang, China, pp 29 33 Kaya, A Scheib, T ( 198 8) Tuning of pid... the previous formula and more commonly known as the Standard format Astrom & Hagglund (2006) Feng & Tan ( 199 8), shown in the form of blocks in figure 2 242 4 Expert Systems for Human, Materials and Automation Will-be-set-by-IN-TECH Fig 2 PID regulator in standard topology Infinite are the industrial processes whose normal function is not the adequate for certain applications This problem, in many cases,... the knowledge model: In this part the need to do a model of complete knowledge model has been detected, from the system itself and the specifications 254 16 Expert Systems for Human, Materials and Automation Will-be-set-by-IN-TECH Fig 17 Systems of Benchmark ordered from lower to higher L/T value Fig 18 Systems of Benchmark arranged from less to more value of response time for expressions with load disturbance... specifications If for instance the case for rule rg 2.1 in which the systems are put together to follow the load disturbance criterion is shown, then refer to figure 19 In the table the values of the specification in each case have been indicated, alongside the expressions for obtaining the parameters used to improve this specification Next, a division 256 18 Expert Systems for Human, Materials and Automation. .. present and future of PID Control, Elsevier Science and Technology, Terrasa, Spain, pp 181 –182 Auslander, D., Takahashi, Y & Tomizuka, M ( 197 8) Direct digital process control: Practice and algorithms for microprocessor application, Proceedings of the IEEE 66(2): 199 – 208 Bennett, S ( 198 4) Nicolas minorsky and the automatic steering of ships, Control System Magazine Vol 4(No 4): 10–15 URL: 10.11 09/ MCS. 198 4.1104827... Loop Conceptual Model Model for a Knowledge Base for Controllers Tuning in Base of Fig 12 General diagram of knowledge for open loop empirical tuning of PID controllers 251 13 252 14 Expert Systems for Human, Materials and Automation Will-be-set-by-IN-TECH Fig 13 Area 1 of the diagram Fig 14 Area 2 of the diagram the expressions of Ziegler-Nichols and Chien, Hrones, Reswick for not being within its scope... best of them for computer-aided design automation engine room in the database application and expert system Based on the results obtained are searched in a database similar ships, ie ships with the greatest similarity weighted summary In the case of 260 Expert Systems for Human, Materials and Automation unsatisfactory results in the calculation of similarity, as a complementary, provided for a neural... Between human and machine: Feedback, Control, and Computing before Cybernetics, Johns Hopkings Paperbacks edition, London Pang, G ( 199 1) An expert adaptive control scheme in an intelligent process control system, Proceedings of the IEEE International Symposium on the intelligent Control, IEEE Press, Arlington, Virginia, pp 13–18 Pang, G ( 199 3) Implementation of a knowledge-based controller for hybrid systems, ... function is the expression 5, which deals with a system of first order G (s) = 1 s+1 (5) 246 8 Expert Systems for Human, Materials and Automation Will-be-set-by-IN-TECH Method Ziegler-Nichols Kp 1.2 a 1.04432 T L Kaya-Scheib Set point regulation minimize IAE 0 .95 K Kaya-Scheib Set point regulation minimize ISE 0.7 195 9 K T L Kaya-Scheib Set point regulation minimize ITAE Chien, Hrones y Reswick load disturbances... is known, and it is exactly adapted to one of the systems referred to in the Benchmark, but it will be carried out when the transfer function is not known or if it is known, and it does not adapt to any of the systems and also if both criteria are contemplated (load disturbance and set point control) The validation is done on 9 systems not contemplated in the Benchmark and it is checked for each one . parameters, and therefore it is not applicable. 246 Expert Systems for Human, Materials and Automation Conceptual Model Development for a Knowledge Base of PID Controllers Tuning in Open Loop 9 Fig regulated systems a unit step is introduced, and after some time a disruption is provoked. As can be seen in the 242 Expert Systems for Human, Materials and Automation Conceptual Model Development for. 2 39 – 244 Roddis, W. M. Kim, and Pasley, Gregory P., ( 199 3) "Knowledge-Based Expert Systems in Concrete Materials: Uniting Specifications, Data, and Models," Presentation at the 199 3