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  • Articles  (36)
  • NDE  (21)
  • integer programming  (15)
  • 1990-1994  (8)
  • 1985-1989  (28)
  • 1960-1964
  • 1950-1954
  • Electrical Engineering, Measurement and Control Technology  (21)
  • Economics  (15)
  • 1
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    Electronic Resource
    Optimizing single-terminal dispatch of large volume trips to trucks (1994)
    Springer
    Annals of operations research 50 (1994), S. 455-471 
    Details
    ISSN: 1572-9338
    Keywords: Truck dispatching ; generalized assignment ; integer programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract In this paper, we consider the problem of delivering large volumes of products from a single supplier to a set of commercial outlets with the use of a non-homogeneous fleet of trucks. The non-homogeneity implies different costs and, hence, traditional methods which measure miles, hours, and/or number of trucks are not appropriate. The problem may be modeled as an elastic generalized assignment problem. A special purpose branch and bound algorithm is developed and a set of real-world distribution problems and solved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02085653
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  • 2
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    Multi-item capacitated lot-sizing by a Cross decomposition based algorithm (1994)
    Springer
    Annals of operations research 50 (1994), S. 557-574 
    Details
    ISSN: 1572-9338
    Keywords: Production ; capacitated lot-sizing ; setup time ; integer programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Multi-item capacitated lot-sizing involves the determination of production quantities in different periods in the presence of resource constraints. The model presented in this paper includes a setup time for the production of a lot of an item. The production of items in a given period is constrained by a limited regular time and a limited overtime. Moreover, the production level of any item in a given period is also limited. This problem is tackled by a Cross decomposition based algorithm which can provide an optimal solution, or a near optimal solution if computational time is restricted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02085658
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  • 3
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    Penalty computations for the set partitioning problem (1993)
    Springer
    Annals of operations research 43 (1993), S. 285-293 
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    ISSN: 1572-9338
    Keywords: Set partitioning ; penalties ; integer programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The computation of penalties associated with the continuous relaxation of integer programming problems can be useful to derive conditional and relational tests which allow to fix some variables at their optimal value or to generate new constraints (cuts). We study in this paper the computation and the use of penalties as a tool to improve the efficiency of algorithms for solving set partitioning problems. This leads to a preprocessing scheme which can be embedded within any exact or approximate algorithm. The strength of these penalties is illustrated through computational results on some real-world set partitioning problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02025299
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  • 4
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    A two-stage approach to multi-period allocation of savings among investment plans (1993)
    Springer
    Annals of operations research 45 (1993), S. 221-242 
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    ISSN: 1572-9338
    Keywords: Finance ; multi-period models ; financial planning and modelling ; insurance ; mathematical programming ; integer programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract This paper presents a two-stage multi-period decision model for allocation of the individual's savings into several investment plans. Although the U.S. economy is used as the background, the modelling methods are general enough to accommodate any tax law. The first stage of the model uses an asset-allocation method based on the single-index model. Because this method is static and does not provide for tax considerations and other constraints, it alone is not enough. The output of this optimal selection is used as exogenous parameters and controls for the second stage of the model which is an integer program. The IP includes fixed charges, statutory and budgetary constraints, a discount rate, and the risk level. We provide an example of this approach to illustrate how an individual can achieve his goals of terminal accumulations while maintaining the risk level, measured by the aggregate beta, he prefers. A linear programming relaxation of the IP model is utilized for sensitivity analysis to examine whether future adjustments in investment strategies are required. The model remains tractable enough for implementation by individuals who may not be experts in mathematical programming and financial planning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02282051
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  • 5
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    Crack detection in conducting materials using SQUID magnetometry (1993)
    Springer
    Journal of nondestructive evaluation 12 (1993), S. 199-207 
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    ISSN: 1573-4862
    Keywords: Crack detection ; NDE ; SQUID magnetometry ; magnetic methods ; current perturbation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A highly sensitive multichannel SQUID gradiometer, optimized uniquely for spatial resolution, was used to map in two dimensions the magnetic field perturbations from circular holes and thin slots in conducting plates and strips, respectively. Holes as small as 0.75 mm radius in electrically conducting plates were measured directly using a single channel. Edge slots as short as 0.5 mm long in conducting strips were detected, using a multiple-channel measurement method which eliminated the effects from the edge of the strip and the current leads. Clear magnetic signatures from these simulated cracks were measured using low current densities. Numerical computations of the theoretical field distributions are presented which confirm the experimental results. Calculations indicate that much smaller defects should be detectable with an optimization of test parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568105
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  • 6
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    Some integer programs arising in the design of main frame computers (1993)
    Springer
    Mathematical methods of operations research 38 (1993), S. 77-100 
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    ISSN: 1432-5217
    Keywords: clustering problem ; design of main frame computers ; graph partitioning problem ; hypergraph partitioning problem ; integer programming ; mathematical modelling ; multiple knapsack problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract In this paper we describe and discuss a problem that arises in the (global) design of a main frame computer. The task is to assign certain functional units to a given number of so called multi chip modules or printed circuit boards taking into account many technical constraints and minimizing a complex objective function. We describe the real world problem. A thorough mathematical modelling of all aspects of this problem results in a rather complicated integer program that seems to be hopelessly difficult — at least for the present state of integer programming technology. We introduce several relaxations of the general model, which are alsoNP-hard, but seem to be more easily accessible. The mathematical relations between the relaxations and the exact formulation of the problem are discussed as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01416008
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  • 7
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    Allocating modelling resources in distributed model management systems (1992)
    Springer
    Annals of operations research 38 (1992), S. 397-419 
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    ISSN: 1572-9338
    Keywords: Decision support systems ; model management ; distributed computing systems ; integer programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Due to the growing popularity of distributed computing systems and the increased level of modelling activity in most organizations, significant benefits can be realized through the implementation of distributed model management systems (DMMS). These systems can be defined as a collection of logically related modelling resources distributed over a computer network. In several ways, functions of DMMS are isomorphic to those of distributed database systems. In general, this paper examines issues viewed as central to the development of distributed model bases (DMB). Several criteria relevant to the overall DMB design problem are discussed. Specifically, this paper focuses on the problem of distributing decision models and tools (solvers), henceforth referred to as theModel Allocation Problem (MAP), to individual computing sites in a geographically dispersed organization. In this research, a 0/1 integer programming model is formulated for the MAP, and an efficient dual ascent heuristic is proposed. Our extensive computational study shows in most instances heuristic-generated solutions which are guaranteed to be within 1.5–7% of optimality. Further, even problems with 420 integer and 160,000 continuous variables took no more than 60 seconds on an IBM 3090-600E computer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02283659
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  • 8
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    Transportation problem with nonlinear side constraints a branch and bound approach (1992)
    Springer
    Mathematical methods of operations research 36 (1992), S. 185-197 
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    ISSN: 1432-5217
    Keywords: Transportation ; branch and bound ; integer programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract In a container terminal management, we are often confronted with the following problem: how to assign a reasonable depositing position for an arriving container, so that the efficiency of searching for and loading of a container later can be increased. In this paper, the problem is modeled as a transportation problem with nonlinear side constraints (TPNSC). The reason of nonlinear side constraints arising is that some kinds of containers cannot be stacked in the same row (the space of storage yard is properly divided into several rows). A branch and bound algorithm is designed to solve this problem. The algorithm is based on the idea of using disjunctive arcs (branches) for resolving conflicts that are created whenever some conflicting kinds of containers are deposited in the same row. During the branch and bound, the candidate problems are transformed into classical transportation problems, so that the efficient transportation algorithm can be applied, at the same time the reoptimization technique is employed during the branch and bound. Further, we design a heuristic to obtain a feasible initial solution for TPNSC in order to prune some candidates as early and/or as much as possible. We report computational results on randomly generated problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01417216
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  • 9
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    Calculation of ultrasonic surface waves from an extended thermoelastic laser source (1989)
    Springer
    Journal of nondestructive evaluation 8 (1989), S. 147-164 
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    ISSN: 1573-4862
    Keywords: Ultrasonic surface waves ; Rayleigh waves ; laser ultrasonics ; thermoelastic ultrasonic source ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A method is developed to calculate ultrasonic surface waveforms generated by an extended laser source, operating in the thermoelastic regime of laser-pulse energy density. This approach integrates over a suitably weighted distribution of point surface centers of expansion, for observation to within 1 mm of the edge of the source. Power spectra as well as both horizontal and vertical displacements are presented and discussed for ultrasonic waveforms on an aluminium surface, for incident laser pulses having Gaussian lateral profiles of various sizes. Far from the source, the waveform is dominated by a dipolar Rayleigh (R) wave, whose amplitude and spectral content depend on laser spot size. Weak, monopolar pulses also occur at the intersection of bulk pressure and shear wavefronts with the surface (denoted assP andsS, respectively). Close to the source, thesP wave amplitude approaches that for theR wave, and overlaps theR wave for large source sizes. The fall-off with distance for bothsP andR waves is given. Finally, the changes in pulse shape and amplitude are calculated when anR wave from an extended thermoelastic source is reflected or transmitted by a right-angled corner of an aluminium block.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570884
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  • 10
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    A domain-extension method for quantitative detection of cavities by infrared scanning (1989)
    Springer
    Journal of nondestructive evaluation 8 (1989), S. 195-211 
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    ISSN: 1573-4862
    Keywords: Infrared scanning ; thermography ; inverse problem ; numerical solution ; domain-extension method ; boundary-element method ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A domain-extension method for quantitative detection of irregular-shape cavities inside irregular-shape bodies is presented. An auxiliary problem is introduced in the solution of the cavities. In the auxiliary problem, the original body domain at the cavity side is extended so that the original cavity walls become interior points. The position of the cavities can then be found by solving the temperature field in the extended domain and matching the temperatures and heat fluxes at the interior points to the conditions imposed on the cavities. A boundary-element method is used for the solution of the auxiliary problem, and by means of four examples, the accuracy of the domain extension method is established. The paper provides the details for the numerical solution of the cavities. Limitation of the method in the detection of multiple cavities is also explored. The domain-extension method has shown to be highly effective in quantitative detection of cavities in single-cavity bodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570887
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  • 11
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    Image-enhanced backlighting: A new method of NDE for translucent composites (1989)
    Springer
    Journal of nondestructive evaluation 8 (1989), S. 181-193 
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    ISSN: 1573-4862
    Keywords: Backlighting ; image processing ; delamination ; cracking ; Kevlar/epoxy ; fiberglass ; NDE ; damage detection ; image enhancement ; composite damage detection ; image-enhanced backlighting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A quick and inexpensive method of nondestructive evaluation is described based on imagenhanced backlighting. The method is capable of being applied to translucent composite materials such as Kevlar/epoxy and glass/epoxy to detect delamination with high resolution. The use of an enhancing dye also makes the method suitable for monitoring surface cracking. The technique has also been demonstrated to be an especially convenient method of observingin situ the growth of cracking and delamination damage as a composite is loaded, and is capable of monitoring thedynamic growth of damage in impact-loading situations. It has been shown to be appropriate for detecting barely visible damage resulting from either impact or static loading on thick laminated structures that even include honeycomb reinforcement.
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    URL: http://dx.doi.org/10.1007/BF00570886
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  • 12
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    Some examples of nondestructive flaw detection by shearography (1989)
    Springer
    Journal of nondestructive evaluation 8 (1989), S. 225-234 
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    ISSN: 1573-4862
    Keywords: Laser ; speckle interferometry ; shearography ; NDE ; metals ; composites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper presents some examples of nondestructive flaw detection using an optical method based on speckle shearing interferometry called shearography. In the method, a structure under study is illuminated by laser and imaged by a special image-shearing camera. After suitable processing, a fringe pattern which represents loci of surface displacement derivatives, i.e., strains, is observed in the image. Since defects in structures usually induce strain concentrations around them and since strain concentrations usually cause perturbations on the surface of structures, shearography reveals defects from anomalies in the recorded fringe pattern. In this work, the technique has been applied to the nondestructive detection of various flaws in plain and welded pipes, composite plates, and other engineering components. A simple model was also developed for the estimation of the depth of disbonds in glassfiber reinforced plastic sheets. Results obtained are good and demonstrate the usefulness of the method as a complement to other conventional NDT techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00633273
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  • 13
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    Generalized resolution and cutting planes (1988)
    Springer
    Annals of operations research 12 (1988), S. 217-239 
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    ISSN: 1572-9338
    Keywords: Propositional logic ; resolution ; integer programming ; theorem proving ; artificial intelligence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract This paper illustrates how the application of integer programming to logic can reveal parallels between logic and mathematics and lead to new algorithms for inference in knowledge-based systems. If logical clauses (stating that at least one of a set of literals is true) are written as inequalities, then the resolvent of two clauses corresponds to a certain cutting plane in integer programming. By properly enlarging the class of cutting planes to cover clauses that state that at least a specified number of literals are true, we obtain a generalization of resolution that involves both cancellation-type and circulant-type sums. We show its completeness by proving that it generates all prime implications, generalizing an early result by Quine. This leads to a cutting-plane algorithm as well as a generalized resolution algorithm for checking whether a set of propositions, perhaps representing a knowledge base, logically implies a given proposition. The paper is intended to be readable by persons with either an operations research or an artificial intelligence background.
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    URL: http://dx.doi.org/10.1007/BF02186368
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  • 14
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    Integrated production scheduling in large-scale flexible electronic parts manufacturing (1988)
    Springer
    Annals of operations research 15 (1988), S. 269-287 
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    ISSN: 1572-9338
    Keywords: Production scheduling ; integer programming ; simulation ; flexible manufacturing ; hierarchical modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract This study reports the development of a production scheduling system for the integrated management of production in large-scale, high-volume electronic assembly lines. The development of the system incorporates control and planning considerations by addressing the interaction of various subsystems. Stochastic and deterministic aspects of the problem environment are appropriately handled via relevant simulation and analytic models. By effecting a hierarchical breakdown of the problem environment, the system produces information used in practical decision making for production planning and scheduling. Procedures used encompass and address considerations for management of work-in-process, optimization of the various subsystems' performance, minimization of setup time effect, and inventory carrying costs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186799
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  • 15
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    Body to Rayleigh wave mode-conversion at steps and slots (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 1-22 
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    ISSN: 1573-4862
    Keywords: Rayleigh waves ; finite-difference method ; defect dimension ; ultrasonic scattering ; mode conversion ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The efficient excitation of Rayleigh waves at surface discontinuities due to body wave incidence has potential as a method for the detection and sizing of surface breaking defects. In this paper, the mode-conversion phenomenon at several types of surface features is studied in detail, using numerical models which employ finite-difference methods. The emphasis is on examining the spectral content of the Rayleigh wave field in order to arrive at a method for relating the spectral information to the defect dimensions. The numerical results are backed up by experimental observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566693
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  • 16
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    ORCHID—A computer simulation of the reliability of an NDE inspection system (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 23-31 
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    ISSN: 1573-4862
    Keywords: NDE ; inspection systems ; reliability ; probability of detection ; computer simulation ; eddy current ; ultrasonics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract CANDU pressurized heavy water reactors contain several hundred horizontally-mounted zirconium alloy pressure tubes. Following a pressure tube failure, a pressure tube inspection system called CIGARette was rapidly designed, manufactured and put in operation. Defects called hydride blisters were found to be the cause of the failure, and were detected using a combination of eddy current and ultrasonic scans. A number of improvements were made to CIGARette during the inspection period. The ORCHID computer program models the operation of the delivery system, eddy current and ultrasonic systems by imitating the on-reactor decision-making procedure. ORCHID predicts that during the early stage of development, less than one blistered tube in three would be detected, while less than one in two would be detected in the middle development stage. However, ORCHID predicts that during the late development stage, probability of detection will be over 90%, primarily due to the inclusion of axial ultrasonic scans (a procedural modification). Rotational and axial slip could severely reduce probability of detection. Comparison of CIGARette's inspection data with ORCHID's predictions indicate that the latter are compatible with the actual inspection results, though the numbers are small and data uncertain. It should be emphasized that the CIGARette system has been essentially replaced with the much more reliable CIGAR system.
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    URL: http://dx.doi.org/10.1007/BF00566694
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  • 17
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    Nondestructive evaluation of ferromagnetic materials by a “magnetometer like” experimental arrangement (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 73-79 
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    ISSN: 1573-4862
    Keywords: Barkhausen noise ; ferromagnetic materials ; stress ; magnetometer ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The paper presents experimental results regarding the influence of mechanical stresses and thermal treatments on the Barkhausen noise and magnetization characteristic of MolyPermalloy and MuMetal ferromagnetic samples. The samples are different in stress magnitude and localization and in their thermal history. The level of Barkhausen noise and the changes in magnetization characteristic are estimated by measuring the sensitivity and transduction gain of “magnetometer like” coils configurations which employ the studied ferromagnetic samples as their nonlinear ferromagnetic cores. The present method is unique in the sense that the two factors (one factor is related to the internal magnetic noise, and the other one is related to the form of the magnetic characteristic) are obtained by employing a single relatively simple experimental arrangement. Various types of stresses, which are different in magnitude and localization, become distinguishable one from the other, when considering their differential effects on the two factors. Several possible experimental arrangements are shown.
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    URL: http://dx.doi.org/10.1007/BF00568885
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  • 18
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    Nondestructive detection of flaws in material using transducer arrays (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 47-55 
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    ISSN: 1573-4862
    Keywords: Ultrasonics ; transducer array ; flaw detection ; signal processing ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In this paper, we describe a system which uses array filters for processing the recordings of an array of transducers for the purpose of locating possible flaws in the material being tested nondestructively. When applied, in order to focus the array outputs at a point inside the material, these filters are able to attenuate, very effectively, interfering residual energy scattered from adjacent flaws, as well as random noise. If there is a flaw at the point of focus, the summed output of the filters will have a large signal at a delay time corresponding to the total travel time for this point; otherwise the output will consist mainly of residual random noise. Thus, the location of flaws or even microflaws in material may be achieved by simple threshold detection.
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    URL: http://dx.doi.org/10.1007/BF00566696
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  • 19
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    Numerical analysis of heat input effects in thermography (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 101-107 
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    ISSN: 1573-4862
    Keywords: NDE ; thermography ; numerical model ; heat input
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A numerical model, suited for use on microcomputers, has been developed to examine the effect of heat input function on surface temperature contrast for passive thermographic NDE. Single and double step input functions have been compared, and the effects of varying pulse length and power, defect condition, defect depth to diameter ratio, and maximum allowed front face temperature rise examined. Results indicate that a two-step heat input function enhances the generated surface temperature contrast by up to 10% over the single pulse and compares well with that generated by contact heating.
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    URL: http://dx.doi.org/10.1007/BF00568888
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  • 20
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    Stationary formulas for computing the response in eddy-current NDE (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 177-180 
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    ISSN: 1573-4862
    Keywords: Eddy current ; NDE ; theoretical models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Stationary or variational formulations have been proven to be useful in a number of electromagnetic problems. This paper presents such a formulation for the response in the eddy-current NDE problem. It thus provides an approach to estimating the response due to arbitrary defects in cases where a reasonable “first guess” for the current distribution responsible for the scattered fields can be obtained.
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    URL: http://dx.doi.org/10.1007/BF00566845
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  • 21
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    On the greedy solution in integer linear programming (1987)
    Springer
    Mathematical methods of operations research 31 (1987), S. A55 
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    ISSN: 1432-5217
    Keywords: integer programming ; greedy method ; Hilbert basis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung In dieser Arbeit wird eine Version des Greedy-Algorithmus zur Lösung ganzzahliger linearer Optimierungsprobleme benutzt, die kein Rucksackproblem als Relaxation verwendet. Das Verfahren basiert auf der natürlichen partiellen Ordnung von Vektoren. Ziel der Arbeit ist es, eine möglichst große Problemklasse zu beschreiben, für die die Greedy-Lösung optimal ist. Die Ergebnisse verallgemeinern Sätze einer früheren Arbeit von Magazine, Nemhauser und Trotter und zeigen gleichzeitig einen Bezug zwischen zwei verschiedenen Gebieten der Kombinatorik auf: des Greedy-Verfahrens und von Hubert-Basen.
    Notes: Abstract A version of the greedy method not using any knapsack relaxation of the integer programming problem is considered in this paper. It is based on a natural partial ordering of the vectors. Our aim is to determine a large class of problems where the greedy solution is always optimal. The results generalize some theorems of an early paper of Magazine, Nemhauser and Trotter and at the same time show a connection between two different notions of combinatorics: the greedy method and the Hilbert basis.
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    URL: http://dx.doi.org/10.1007/BF01258608
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  • 22
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    An exact algorithm for solving a capacitated location-routing problem (1986)
    Springer
    Annals of operations research 6 (1986), S. 291-310 
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    ISSN: 1572-9338
    Keywords: Capacitated location-routing ; integer programming ; algorithm ; least cost
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract In location-routing problems, the objective is to locate one or many depots within a set of sites (representing customer locations or cities) and to construct delivery routes from the selected depot or depots to the remaining sites at least system cost. The objective function is the sum of depot operating costs, vehicle acquisition costs and routing costs. This paper considers one such problem in which a weight is assigned to each site and where sites are to be visited by vehicles having a given capacity. The solution must be such that the sum of the weights of sites visited on any given route does not exceed the capacity of the visiting vehicle. The formulation of an integer linear program for this problem involves degree constraints, generalized subtour elimination constraints, and chain barring constraints. An exact algorithm, using initial relaxation of most of the problem constraints, is presented which is capable of solving problems with up to twenty sites within a reasonable number of iterations.
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    URL: http://dx.doi.org/10.1007/BF02023807
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  • 23
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    Depth measurement for cracks in corners using ultrasonic Rayleigh waves (1986)
    Springer
    Journal of nondestructive evaluation 5 (1986), S. 179-187 
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    ISSN: 1573-4862
    Keywords: Ultrasonic Rayleigh waves ; crack depth measurement ; corner cracks ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The scattering of ultrasonic Rayleigh waves incident normally on corners containing cracks is considered by using elastodynamic ray theory. Detailed calculations are presented for vertical and horizontal cracks in right-angle corners in aluminium. It is shown that crack depth can be measured simply from the spacing of interference fringes in the high-frequency spectra of either the back- or forward-scattered Rayleigh waves, given only a knowledge of the Rayleigh wave speed. Use of the back-scattered wave is preferable because its fringes show stronger modulation, and because an experiment requires a single transducer and access to only one face of the specimen. The technique is applicable without modification to the more general case of a crack at any angle in a corner of any angle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570627
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    Ultrasonic characteristics of graphite/epoxy composite material subjected to fatigue and impacts (1986)
    Springer
    Journal of nondestructive evaluation 5 (1986), S. 119-131 
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    ISSN: 1573-4862
    Keywords: graphite/epoxy ; composites ; ultrasonics ; stress wave factor ; fatigue life ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Fiber-reinforced composites, because of their superior specific strengths and stiffnesses, are used in many aircraft components. However, in this application these composites are subjected not only to fatigue loading, but to occasionally high velocity impact due to the bird injection, hail, dust, and rain. Thus, it is important to evaluate the residual life and degradation due to combined fatigue and impact loadings. Unidirectional graphite epoxy composites (MA8276-Tiger) which are used in the aerospace industry were impacted by a free falling weight at energy levels of 0.567j, 1.134j, and 1.571j [impact energy toughness (j/cm3); 0.12, 0.24, 0.34], respectively. The subsequent changes/degradation in elastic moduli, strength, toughness, and fatigue properties were measured after different number of impacts. It was found that for all energy levels these properties vary linearly with the number of impacts. Furthermore, attenuation changes is not a good ultrasonic parameter for degradation estimation, since it does not incorporate the micro- and macrocracks beyond the impact point. However, these micro- and macrocracks have significant effect on the mechanical properties. In contrast to the attenuation, the stress wave factor, which indicates the efficiency of wave propagation along the specimen, correlates very well with degradation, and it can be used effectively to measure the residual strength after impact. Ultrasonic characteristic on specimens subjected to combined fatigue and impact were also studied. Based on these experiments, it is concluded that the loss in fatigue residual life due to impact loads may be predicted by measuring the effects of the impact load on attenuation and stress wave factor. It was found that the reduction in fatigue life is proportional to sudden changes in attenuation and stress wave factor. Damage accumulation models based on Coffin-Manson equation, was suggested for impact and combined fatigue and impact. It was found that residual properties and fatigue life can be estimated from these models.
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    URL: http://dx.doi.org/10.1007/BF00570621
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    Elastodynamic scattering by fluid-filled nonplanar cracks (1986)
    Springer
    Journal of nondestructive evaluation 5 (1986), S. 161-168 
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    ISSN: 1573-4862
    Keywords: Crack ; nonplanar ; fluid filled ; scattering ; null field ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A recent modification of the null field approach is adapted to the study of scattering of elastic waves by fluid-filled nonplanar cracks. The fluid-filled crack is modeled as a surface over which friction-free boundary conditions apply. A closed surface is formed by adding a fictitious surface, on which latter surface boundary conditions of welded contact are applied. The surface fields on the closed surface are expanded in vector spherical harmonics in a manner which takes the edge conditions into account. Some numerical results on farfield quantities, such as scattering cross sections and backscattering amplitudes (both in the frequency and time domains), are presented for rotationally symmetric cracks.
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    URL: http://dx.doi.org/10.1007/BF00570625
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    A note on aggregating constraints in integer programming (1986)
    Springer
    Mathematical methods of operations research 30 (1986), S. A79 
    Details
    ISSN: 1432-5217
    Keywords: Aggregation of constraints ; integer programming ; linear and nonlinear constraints
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung Die Zusammenfassung von Restriktionen ist eine Technik zur Lösung ganzzahliger Optimierungsaufgaben. Es wird ein Resultat von Zionts modifiziert. Ohne diese Modifikation gibt es nämlich ein Gegenbeispiel zur Behauptung. Ferner wird ein Satz von Bradley über die Zusammenfassung nichtlinearer Funktionen etwas verallgemeinert.
    Notes: Abstract To aggregate constraints is a technique for solving the integer programming problem. In this note we modify a result of Zionts (1974); without this modification, there is a counterexample for Zionts' result. Further, we give an elegant theorem which considers the aggregation of nonlinear constraints.
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    URL: http://dx.doi.org/10.1007/BF01918634
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    The part families problem in flexible manufacturing systems (1985)
    Springer
    Annals of operations research 3 (1985), S. 277-300 
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    ISSN: 1572-9338
    Keywords: Clustering ; integer programming ; flexible manufacturing ; group technology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Parts grouping into families can be performed in flexible manufacturing systems (FMSs) to simplify two classes of problems: long horizon planning and short horizon planning. In this paper the emphasis is on the part families problem applicable to the short horizon planning. Traditionally, parts grouping was based on classification and coding systems, some of which are reviewed in this paper. To overcome the drawbacks of the classical approach to parts grouping, two new methodologies are developed. The methodologies presented are very easy to implement because they take advantage of the information already stored in the CAD system. One of the basic elements of this system is the algorithm for solving the part families problem. Some of the existing clustering algorithms for solving this problem are discussed. A new clustering algorithm has been developed. The computational complexity and some of the computational results of solving the part families problem are also discussed.
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    URL: http://dx.doi.org/10.1007/BF02023710
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    An efficient alorithm for the general multiple-choice knapsack problem (GMKP) (1985)
    Springer
    Annals of operations research 4 (1985), S. 253-283 
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    ISSN: 1572-9338
    Keywords: Mathematical programming ; integer programming ; general multiple-choice knapsack problem ; knapsack problem ; capital budgeting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract A common problem frequently faced by business firms and individual investors is to select a few investment opportunities from many available possibilities. This problem, in its simplest form, can be modeled as a 0–1 knapsack problem. In a more general investment scenario, however, we obtain a model which is a general knapsack problem with a multiple-choice constraint. To solve this problem, an efficient enumerative algorithm is developed. The algorithm includes an efficient procedure to solve the LP-relaxed problem, a reduction algorithm which may allow the initial fixing of some of the variables, and various other implicit enumeration criteria derived from the group problem. Extensive computational experience illustrates the efficiency of the algorithm and related results.
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    URL: http://dx.doi.org/10.1007/BF02022043
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    Interactive decision software and computer graphics for architectural and space planning (1985)
    Springer
    Annals of operations research 5 (1985), S. 557-573 
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    ISSN: 1572-9338
    Keywords: Modeling ; micro-computers ; integer programming ; nonlinear programming ; heuristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract We describe the development and successful implementation of a decision support system now being used by several leading firms in the architecture and space planning industries. The system, which we call SPDS (spatialprogrammingdesignsystem) has the following characteristics: (i) user-friendly convenience features permitting architects and space planners to operate the system without being experienced programmers; (ii) interactive capabilities allowing the user to control and to manipulate relevant parameters, orchestrating conditions to which his or her intuition provides valuable input; (iii) informative and understandable graphics, providing visual displays of interconnections that the computer itself treats in a more abstract methematical form; (iv) convenient ways to change configurations, and to carry out ‘what if’ analyses calling on the system's decision support capabilities; (v) a collection of new methods, invisible to the user, capable of generating good solutions to the mathematical programming problems that underlie each major design component. These new methods succeed in generating high quality solutions to a collection of complex discrete, highly nonlinear problems. While these problems could only be solved in hours, or not at all, with previously existing software, the new methods obtain answers in seconds to minutes on a minicomputer. Major users, including Dalton, Dalton, Newport, and Marshal Erdwin, report numerous advantages of the system over traditional architectural design methods.
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    URL: http://dx.doi.org/10.1007/BF02023611
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    Testing steel-cord belt splices with a magnetic conveyor belt monitor (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 15-19 
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    ISSN: 1573-4862
    Keywords: Magnetic induction ; testing ; steel cord ; belt ; splices ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Steel-cord belt splices fail for a variety of reasons, including corrosion, poor vulcanising, and incorrect construction. The latter often leads to early failure. A conveyor belt monitor (CBM) has been used to evaluate the splice lay-up. The mass of the overlapping cords and their magnetic signature are used to rapidly locate suspect splices in the belt. The general shape of the magnetic signature for ideal splices will be discussed.
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    URL: http://dx.doi.org/10.1007/BF00568759
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    Three dimensional strain measurements with x-ray energy dispersive spectroscopy (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 21-25 
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    ISSN: 1573-4862
    Keywords: Profile fitting ; residual stress ; strain mapping ; x-ray diffraction ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A feasibility study was performed to show the ability of energy dispersive x-ray diffraction (EDXRD) to measure three dimensional strain distributions in thick industrial materials. Photon energies up to 130 keV were used to guarantee penetration through the sample and curve fitting techniques applied to peak position determination. This system was used to measure the strain gradient through the thickness of a 9.5 mm thick cantilevered steel bar.
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    URL: http://dx.doi.org/10.1007/BF00568760
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    Impedance of single-turn coil surrounding a conducting cylinder with a flaw (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 53-56 
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    ISSN: 1573-4862
    Keywords: Eddy current ; flaw ; cylinder ; Born approximation ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The impedance of a single-turn coil which surrounds a conducting cylinder with a flaw is calculated employing Green's function technique. The Born approximation is used in order to know how the impedance change due to the presence of a flaw depends on the conductivity and size of a flaw.
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    URL: http://dx.doi.org/10.1007/BF00568764
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    A surface acoustic wave technique for monitoring the growth behavior of small surface fatigue cracks (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 1-7 
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    ISSN: 1573-4862
    Keywords: Surface acoustic waves ; fatigue ; small crack growth ; crack opening behavior ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The theory of Kino and Auld which relates the reflection coefficient of acoustic waves from a crack to its size is summarized. A scattering model is evaluated from this theory concerning the reflection of surface acoustic waves (SAW) from a small surface fatigue crack at a frequency such that the crack depth is much smaller than the acoustic wavelength. Acoustic predictions of crack depth are compared to postfracture measurements of depth for small surface cracks in Pyrex glass, 7075-T651 aluminum, and 4340 steel. Additionally, the minimum detectable crack depth as limited by the acoustic noise level is determined for several typical aluminum and steel alloys. The utility of SAW reflection coefficient measurements for inferring crack depth, crack growth, and crack opening behaviorin situ during fatigue cycling is discussed.
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    An acoustoelastic determination of the stress tensor in textured metal sheets using the birefringency of ultrasonic shear waves (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 45-52 
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    ISSN: 1573-4862
    Keywords: Acoustoelasticity ; shear waves ; stress measurements ; birefringency ; polarization ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A theory is formulated that enables one to determine two-dimensional applied stresses in sheets of slightly orthotropic material by means of ultrasonic shear waves To relate experimental acoustic data to a stress tensor we introduce an acoustoelastic tensork. Our experimental technique can measure times of flight and polarization angles within 1/3 nsec and 1°, respectively. In the case of the aluminium 2024-T351 alloy we used, calibration using tensile specimens leads to a nonisotropick tensor. Measurements of the complete (plane) stress tensor are carried out in the center of a compressed disc.
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    URL: http://dx.doi.org/10.1007/BF00568763
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    A new acoustic spectroscopy: Resonance spectroscopy by the MIIR (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 69-79 
    Details
    ISSN: 1573-4862
    Keywords: Acoustic scattering ; acoustic spectroscopy ; resonance spectrum ; resonance identification ; circumferential waves ; visualization ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Recent and remarkable advances in the experimental study of acoustic scattering from targets immersed in water are leading to a new spectroscopy: resonance acoustic spectroscopy. The discovery and improvement of an intriguing method, the Method of Isolation and Identification of Resonances (MIIR), has made possible experimental determination of the eigenfrequency spectra of aluminum-elastic cylinders and cylindrical shells. This method gives a quasilinear “resonance spectra.” In addition, it shows the importance of circumferential waves which generate standing waves. They allow us to explain the “reradiation” of targets after the end of insonification. The MIIR has numerous applications, especially in “underwater acoustics” and “nondestructive testing.”
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    URL: http://dx.doi.org/10.1007/BF00566957
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    Ultrasonic crack characterization via a constrained inversion algorithm (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 37-43 
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    ISSN: 1573-4862
    Keywords: Kirchhoff approximation ; crack scattering ; ultrasonics ; NDE ; inverse scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The Kirchhoff approximation is used to show that the time domain impulse response of an isolated flat crack can be given a simple geometrical interpretation in terms of the derivative of a projected length function. For an elliptical crack, this derivative can be obtained explicitly to yield the two edge-diffracted waves which originate from the “flashpoints” of the crack. An explicit coordinate invariant expression is obtained from this elliptical crack solution which relates the time difference, Δt, between the arrival of these edge-diffracted waves and the crack size and orientation. Previously, we have proposed that this expression, together with Δt measurements in different scattering directions, could be used in a regression analysis as the basis for performing a constrained inversion of crack scattering data (i.e., where we attempt to obtain the “best” equivalent flat elliptical crack that fits the scattering measurements). Here we will demonstrate some results of applying the proposed algorithm using “noisy” synthetic data. The sensitivity of the results to both, number of measurements and transducer orientation, will be discussed.
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    URL: http://dx.doi.org/10.1007/BF00568762
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