ALBERT

Notes: X-ray diffraction (XRD) patterns from nominally β-SiC specimens often differ from those expected for the cubic crystal structure. These differences include the presence of additional peaks, enhanced background intensities, peak broadening, changes in relative peak heights, and shifts in peak positions. It has long been recognized that they are due to the presence of stacking faults, and models relating the experimental observations to stacking fault population have continued to evolve. The presence and relative magnitude of these features vary among different β-SiC specimens. In this work, computer simulations were used to show that the variations are closely related to differences in the type and spatial distribution of stacking faults in each specimen. In these simulations, stacking sequences were generated using a selectively activated 1-D Ising model with a Boltzmann-type probability function for specifying errors, which allows a wide variety of fault configurations to be generated. Direct correlations between different features in the XRD data to the underlying fault population are demonstrated, which are discussed in this paper. It is also shown that this computer model is general, in the sense that many of the models presented in prior work can be interpreted as limiting cases of it.

Notes: Abstract— This paper examines the application of the Jk, L and M integrals, in complex-variable form, to the Boussinesq wedge. The wedge is symmetrical and subjected to a point couple and point forces at the apex of the wedge. In the case of a point couple acting at the wedge apex the Jy, L and M integrals are found to vanish for all wedge angles whereas Jx displays a 1/r3 path-dependence; where r is a radial dimension measured from the wedge apex. When the wedge is subjected to point forces at the wedge apex then Jx and Jy are 1/r path-dependent whereas L and M are path-independent.The property that the L and M integrals are path-independent for the Boussinesq wedge is applied to the problem of determining the modes I and II stress intensity factors for a corner-loaded edge crack in a half-plane subjected to both normal and parallel point forces to the free surface of the half-plane.

Notes: Abstract— Fatigue tests were performed on thin-walled tubular specimens of S45C steel under tension-compression, pure torsion, in-phase and out-of-phase axial-torsional loadings. The relationship between cracking behaviour and stress components on the crack plane was investigated. Measurement of microcrack density showed that microcracking was governed predominantly by the shear stress amplitude acting on the crack plane for all loading conditions. The failure crack was formed by coalescence of many cracks initiated near the maximum shear planes. The cracks grew turning their orientation to the direction perpendicular to the maximum normal stress. The transition of crack orientation occurred at relatively longer crack lengths at a higher stress ratio. The crack growth behaviour for all loading modes can be correlated using an equivalent strain intensity parameter based on shear and normal strains on the crack plane.

Notes: Abstract— A ductile medium strength steel has been modelled by means of the Gurson model, and been used to investigate the effect of crack tip constraint in several fracture mechanics specimens. Both numerical and experimental results have been obtained, in the course of the crack extension process, for single edge notch bending specimens with different crack length-to-width ratios. The geometries with the shorter cracks always exhibited higher J values at initiation and steeper J crack growth resistance curves, and these results have been explained in terms of the stress and strain fields and damage development in the region ahead of the crack tip.

Notes: Abstract— It is shown that autofrettage at low temperatures is superior to autofrettage at room temperature in enhancing the fatigue resistance of thick-walled tubes against pulsating internal pressure. The physical reason is based on the well-known temperature dependence of the mechanical behaviour of metals and alloys which generally exhibit an enhancement of both the yield stress and strain hardening behaviour at lower temperatures. As a consequence, significantly larger compressive residual hoop stresses can be introduced during pressurization at low temperatures than at room temperature. Experimental data obtained on thick-walled tubes of the metastable austenitic stainless steel AISI 304 L which were subjected to pulsating internal pressure at room temperature after autofrettage at temperatures between-110°C and room temperature are presented. These data demonstrate convincingly the advantages offered by low-temperature autofrettage in enhancing both the fatigue life in the finite-life region and the fatigue endurance limit in comparison with autofrettage at room temperature. In conclusion, some specific materials requirements for optimum low-temperature autofrettage performance are discussed.

Notes: Abstract— A new single-specimen testing method, the normalization method with the so-called LMN calibration function, based on the load separation principle and function calibrations from an individual test record, was used to construct J-R curves directly from load versus load-line displacement records without any additional on-line crack-length monitoring equipment. The research was done on CT-specimens of a glassy polymer PVC at different crosshead speeds ranging from 0.01 to 50 mm/min. The J-R curves evaluated from the normalization method are in good agreement with those from the conventional multiple-specimen testing method in the whole range of the tested crosshead speeds. The results demonstrated the applicability of the normalization method for developing J-R curves at different crosshead speeds in PVC. The crack initiation J-integral values, J0.2, showed a two-regime dependence on the crosshead speeds in the tested crosshead speed range.

Notes: Abstract— Biaxial fatigue tests were conducted on a high strength spring steel using hour-glass shaped smooth specimens. Four types of loading system were employed, i.e. (a) fully reversed cyclic torsion, (b) uniaxial push—pull, (c) fully reversed torsion with a superimposed axial static tension or compression stress, and (d) uniaxial push—pull with a superimposed static torque, to evaluate the effects of mean stress on the cyclic stress—strain response and short fatigue crack growth behaviour. Experimental results indicate that a biaxial mean stress has no apparent influence on the stress—strain response in torsion, however a superimposed tensile mean stress was detrimental to torsional fatigue strength. Similarly a superimposed static shear stress reduced the push—pull fatigue lifetime. A compressive mean stress was seen to be beneficial to torsion fatigue life. The role of mean stress on fatigue lifetime, under mixed mode loading, was investigated through experimental observations and theoretical analyses of short crack initiation and propagation. Using a plastic replication technique the effects of biaxial mean stress on both Stage I (mode II) and Stage II (mode I) short cracks were evaluated and analysed in detail. A two stage biaxial short fatigue crack growth model incorporating the influence of mean stress was subsequently developed and applied to correlate data of crack growth rate and fatigue life.

Notes: Abstract— The development of fatigue damage in Co45Ni specimens during push—pull and reversed torsion tests, performed inside a scanning electron microscope, was observed and the different stress states compared. It appeared that transgranular crack initiation and development is delayed and intergranular crack initiation promoted under torsional loading. This was explained in terms of reduced surface distortion at the emergence of persistent slip bands (PSBs) and smaller compatibility stresses at the PSB-matrix interfaces. The influence of the mechanical strength of grain boundaries on the difference between tensile and torsional fatigue lives is discussed.

Notes: Abstract— A Fourier series approach is proposed to calculate stress intensity factors using weight functions for semi-elliptical surface cracks in flat plates subjected to two-dimensional stress distributions. The weight functions were derived from reference stress intensity factors obtained by three-dimensional finite element analyses. The close form weight functions derived are suitable for the calculation of stress intensity factors for semi-elliptical surface cracks in flat plates under two-dimensional stress distributions with the crack aspect ratio in the range of 0.1 ≤a/c≤ 1 and relative depth in the range of 0 ≤a/t≤ 0.8. Solutions were verified using several two-dimensional non-linear stress distributions; the maximum difference being 6%.

Notes: Abstract— A conventional finite element method may show a weakness when determining the hot spot stress distributions in the brace/chord intersection region of offshore tubular joints. This is because the chosen element displacement functions do not implicitly satisfy the conditions which prevail on the free surfaces. A procedure has been proposed to modify the conventional finite element method so as to allow the hot spot stresses, which occur at the free boundary of the weld toe of tubular joints, to be determined with improved accuracy. The results obtained by this modified method are compared with both an experimental and a traditional finite element solution. The comparison shows that the modified solution is in better agreement with the experimental data as compared with the traditional solution.

Notes: Abstract— Simple extensions to the standard deep notch bend test procedure are suggested to allow the collection of data relevant to the energy dissipation rate, D, crack opening angle, COA, and J, all for arbitrarily large amounts of growth in extensive plasticity. The methods of analysis are detailed for real elastic-plastic behaviour of a high strength low-hardening type metal with a view to encouraging use on a wider range of materials. A proposal is made, and equations given, that the particular version of J used for an R-curve derived from the area under the loading diagram, should correspond to the value of the far-field integral, Jff.The relationship between the global measure of COA that emerges from D and the local crack tip opening angle, CTOA, as used in computational studies, is established. Transferability of CTOA data is examined in the light of effects of size and configuration. An explicit rule of the form CTOA √G =f (material and configuration) is proposed for the modelling of ductile growth in finite element studies. It is applied to a set of data in the literature, for the variation of CTOA with size in the deep notch bend test and for the configurations, bending, double edge and centre cracked tension.

Notes: Abstract— In this investigation the Electron Channelling Contrast (ECC) technique in scanning electron microscopy (SEM) was applied to reveal the dislocation structures in the vicinity of surface fatigue cracks in comparison to those of cyclically-deformed recrystallized polycrystalline copper. The plastic zone around a fatigue crack was found to consist of an innermost region containing cells, followed by a region containing dense veins and PSBs, surrounded by a structure of loose veins, bundles and loop patches typical of the cyclically deformed matrix. A relation between plastic strain amplitude values deduced from cyclic stress-strain investigations and the dislocation structures near fatigue cracks are given. Typical regions of damage accumulation were identified and plastic strain contours for surface fatigue cracks established. The essentially non-destructive ECC technique is particularly suited to identify the changes in mesoscopic dislocation structures from surface layers to the interior of specimens over large specimen areas.

Notes: Abstract— The propagation behaviour of fatigue cracks emanating from pre-cracks was numerically simulated to evaluate the development of crack closure with crack growth. The crack opening stress intensity factor at the threshold was approximated as a function of the applied stress and the amount of crack extension. Pre-cracked specimens of a medium-carbon steel with a small surface crack and a single-edge crack were fatigued to investigate experimentally the initiation and propagation of cracks from pre-cracks. Crack closure was dynamically measured by using an interferometric strain/displacement gauge. The threshold condition of crack initiation from pre-cracks was given by a constant value of the effective stress intensity range which was equal to the threshold value for long cracks. The cyclic R-curve was constructed in terms of the threshold value of the maximum stress intensity factor as a function of crack extension approximated on the basis of the experimental and numerical results. The cyclic R-curve method was used to predict the fatigue thresholds of pre-cracked specimens. The predicted values of the fatigue limits for crack initiation and fracture, and the length of non-propagating cracks agreed very well with the experimental results.

Notes: Abstract— A basic study was performed on the evolution of three-dimensional shapes of small surface fatigue cracks during fatigue, and the effect of this evolution on small-crack growth behavior of a titanium-base alloy. Specifically, the nature and the magnitude of variations in crack aspect ratio, a/c (a is the crack depth and c is the half-surface crack length), during cyclic crack growth and its impact on growth rates have been studied. Experiments were performed on naturally initiated micro-cracks in a microstructure consisting of equiaxed primary-α2 phase in a Widmanstätten (transformed β) matrix. Several cracks under stress ratio (R) levels of 0.1 and −1, were studied. A specialized experimental system, consisting of a laser interferometer (to measure precisely the small-crack surface displacements), and a photo microscope (to automatically and continuously photograph the fatigue micro-cracks) was employed in the study. Apparent aspect ratios of surface cracks were calculated from the compliance response and the surface crack length data as a function of fatigue cycles. These data enabled accurate calculations of growth rates at the surface crack tip as well as the tip at depth in the bulk over the entire crack growth period, thus giving an insight into the crack growth process. Measurements of closure levels of small cracks were also performed and were used to partly account for the differences in growth rates. In the comparisons of small-crack growth data with the large-crack data, surface growth rates correlated relatively well with the large-crack data. Growth rates at depth exhibited large variations due to the irregularity of crack fronts at this location, and these rates deviated significantly from the large-crack behavior. Additionally, these growth rates varied between different cracks. An attempt was made to rationalize these observations in terms of the effects of inhomogeneities present in the microstructure.

Notes: Abstract— A new technique, known as crack modelling, is used here to predict fatigue failure in a crankshaft component. The technique uses a linear elastic finite element (FE) analysis to derive a stress intensity factor (K) for the component under load. The novel feature of the technique is that K is calculated without introducing a crack into a component; the stress field around the maximum stress point is examined and compared to that for a standard centre-cracked plate. The fatigue limit for a crankshaft was successfully predicted, when compared to experimental data. The only material parameter required for this prediction was the threshold stress intensity range, ΔKth.

Notes: Abstract— The effects of bluing, associated with drawing strain, on the fatigue strength of eutectoid steel wires have been investigated. The fatigue limit increases by bluing and the increase is more significant with higher drawing strain. The peak in the fatigue limit with regard to the drawing strain in the wires, at a strain of 2.5, disappears after bluing. On the other hand, in the ferritic steel wires investigated for comparison, the fatigue limit gradually increases with the drawing strain up to 7.7. Furthermore, no appreciable change in the fatigue limit due to bluing is found. Based on the results of hardness tests on fatigue specimens with- and without-bluing, it is deduced that the decrease of the fatigue limit beyond the peak drawing strain in the eutectoid steel wire can partly be attributed to insufficient locking of the high-density dislocations by solute atoms. The effect of relaxation of residual stress during bluing is also briefly discussed.

Notes: Abstract— It is well known that for very short cracks the stress intensity factor K is not a suitable parameter to estimate the stress level over the small but finite Stage II process zone activation region of size rs near the crack tip, within which crack growth events take place. A critical appreciation of the reasons for the limitations on the applicability of ΔK as a fatigue crack propagation (FCP) parameter, when the crack length a is of the same order of magnitude or smaller than the size of the ‘fatigue-fracture activation region’, rs is presented. As an alternative to ΔK the range Δσs of the cyclic normal stress at a point situated at the fixed distance s=rs/2, ahead of the crack tip, inside the fatigue-fracture activation region, is proposed. It is observed that the limitation on the use of ΔK when the crack is short, is mathematical (and not physical) but this inconvenience is easily circumvented if the stress Δσs at the prescribed distance is used instead of ΔK since nowadays Δσs can be obtained numerically by using finite element methods (FEM). It follows that the parameter Δσs is not restricted by the mathematical limitations on ΔK and so it would seem that there is, a priori, no reason why the validity of the parameter Δσs cannot be extended to short cracks. It is shown that if the Paris law is expressed in terms of Δσs (πrrs)½ instead of ΔK the validity of the modified Paris law can be extended to short cracks.A coherent estimate of the value of the fatigue-fracture activation region rs is derived in terms of the fatigue limit ΔσFL obtained from S-N tests and of the threshold value ΔKth obtained from tests on long cracks where both relate to Stage II crack growth that ends in failure, namely, rs= (ΔKth/ΔσFL)2/π. An overall, threshold diagram is presented based on the simple criterion that, for sustained Stage II FCP, Δσs must be greater than ΔσFL. The study is based on a simple continuum mechanics approach and its purpose is the investigation of the suitability of both ΔK and Δσs to characterise the crack driving force that activates complex fracture processes at the microstructure's scale. The investigation pertains to conditions that lead to the ultimate failure of the component at values of Δσs 〉 ΔσFL.

Notes: Abstract— The boundary value problem for an arbitrarily shaped plane crack embedded in a 3D linear elastic solid can be reduced to a governing hyper-singular integral equation. A discretizing procedure based on a triangulation of the crack area has been offered in Part I of this work. The main goal of Part I is to introduce the analytical results for the 18 resulting finite-part integrals defined over a triangular mesh area. The finite-part integrals occur in those triangles where the source point coincides with one of the element nodes. Mostly the source point lies outside of the considered triangle. In these cases the occurring area integrals are regular.The aim of Part II is, therefore, the derivation of the closed form expressions for the relevant 18 regular area integrals. The resulting relations are of algebraic form which can easily be coded in compact form. Their numerical proof by two different methods shows the highest accuracy and, therefore, the correctness of the final solutions. The relevant numerical results are offered in Appendix I.With the formulae provided in Part I and Part II of the paper the determination of the coefficient matrix, necessary for the calculation of COD values from a linear equation system, is precise and needs only minimum computer time.

Notes: Abstract— Circumferentially notched cylindrical specimens are tested in torsion to obtain critical J values from crack resistance curves. The specimens are explosion cladded, half ferrite, half austenite, with the interface perpendicular to the cylinder axis and the circumferential notch at, or parallel to, the interface. Critical J values for crack extension in mode III were found to be a factor 1.1 to 2.1 higher than under comparable mode I loading.

Notes: Abstract— Strength measurements are becoming increasingly important for electroceramics. Bending of specimens small enough to be cut out of small electroceramic components may be one possibility. Therefore the miniaturisation of the 4-point bend-test for ceramic specimens is now being attempted. In this paper the errors in determining the flexural strength arising from the test principle itself, plus the geometry and measuring inaccuracies are calculated and expressed as a function of the outer span length. Contact pressure and a tolerable total measuring inaccuracy determines the dimensions of miniature specimens and fixtures. The possibilities of appropriate specimen preparation are also investigated.Ceramic materials show a volume (i.e. a specimen size) dependence of strength which is described by Weibull's statistical theory. The applicability of the miniature bend-fixtures is demonstrated by measuring this volume effect.

Notes: Abstract— This paper describes a versatile technique for simulating the fatigue growth of a wide range of planar cracks of practical significance. Crack growth is predicted on a step-by-step basis from the Paris law using stress intensity factors calculated by the finite element method. The crack front is defined by a cubic spline curve from a set of nodes. Both the 1/4-node crack opening displacement and the three-dimensional J-integral (energy release rate) methods are used to calculate the stress intensity factors. Automatic remeshing of the finite element model to a new position which defines the new crack front enables the crack propagation to be followed. The accuracy and capability of this finite element simulation technique are demonstrated in this paper by the investigation of various problems of both theoretical and practical interest. These include the shape growth trend of an embedded initially penny-shaped defect and an embedded initially elliptical defect in an infinite body, the growth of a semi-elliptical surface crack in a finite thickness plate under tension and bending, the propagation of an internal crack in a round bar and the shape change of an external surface crack in a pressure vessel.

Notes: Abstract— Cold-expansion of fastener holes is now commonly used within the aerospace industry to increase the fatigue endurance of airframes. Although a number of methods of cold expansion are possible, the split-sleeve cold-expansion process is the most widely accepted and is frequently used in the repair and manufacture stages of both military and civil aircraft. In the present work, the redistribution of residual hoop stresses due to the application of constant amplitude fatigue loading at 4% cold-expanded holes has been studied. A modified Sachs method was adopted to evaluate the residual stress profiles and a replication technique was used to quantify crack growth. It was found that the decay of the residual hoop stress profile near the bore of the hole was due to the initiation and growth of small fatigue cracks. Cracks were found to initiate both near and below the fatigue limit, but subsequently arrested so stabilising the overall residual stress profile.

Notes: Abstract— The factors affecting the fatigue strength of nitrided titanium were clarified. The fatigue strength depended strongly on the fracture strength of the compound layer formed on the surface by nitriding. We found a Hall-Petch relationship between the fatigue strength of nitrided titanium and the grain size. The findings indicated that the reduction in the fatigue strength by nitriding results from both the formation of the compound layer possessing low fracture strength and grain growth occurring from ordinary nitriding. Furthermore, low-temperature nitriding (620°C, 24 h) was proposed to suppress grain growth. This treatment method improved not only the wear resistance and the corrosion resistance but also the fatigue strength of titanium.

Notes: The paper defines entrepreneurship as about ‘self-competition’, the quest to test self-ability: Can a future self achieve greater goals than what has been so far achieved? Self-competition involves the development of ability and, hence, ex post assessment of ability is uncertain. Such uncertainty occasions either immobilizing anxiety (Buridan's ass) or entrepreneurial action. No such uncertainty surrounds the assessment of risk probability characterizing events such as floods and stock market crashes. An observable prediction of the proposed uncertainty/risk dichotomy is that insurance, which concerns risk, cannot crowd out religion and other belief systems which appeal to uncertainty.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGIn diesem Papier wird Unternehmertum im Sinne von ‘Selbst-Konkurrenz’ deftniert, als Streben, die eigenen Fähigkeiten unter Beweis zu stellen: Kann das zukünftige Ich höhere Ziele als bisher erreichen?Selbst-Konkurrenz beinhaltet die Entwicklung von Fähigkeiten, und daher ist deren ex post Einschätzung unsicher. Diese Unsicherheit führt entweder zu einer lähmenden Angst (Burdians Esel) oder zu unternehmerischer Aktivität. Im Gegensatz dazu ist die Einschätzung der Risikowahrscheinlichkeit von Überschwemmungen oder Kursschwankungen an der Börse nicht von einer solchen Unsicherheit geprägt. Als beobachtbare Voraussage aus der vorgeschlagenen Unsicher-heit/Risiko-Dichotomie heraus ergibt sich, dass eine dieses Risiko betreffende Versicherung nicht in der Lage ist, Religion und andere Glaubenssysteme, die sich auf Unsicherheit bezichen, zu verdrängen.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉCe papier définit ľesprit entrepreneur comrne ‘une concurrence de soi’, la quete d'éprouver la capacityé de soi: Est-ce possible qu'un futur-soi puisse achever de plus grands buts qu'il a déjà accomplis? Une concurrence de soi consiste du développcinent de sa capacityé, done, ľévaluation ex past de cette capacityé n'est pas certaine.Une telle incertitude mène à une anxiété paralysante (ľǎne de Buridan) ou àľ action entreprenante. Une incertitude de la sorte n'entoure pas ľévaluation de la probabilityé de risque qui caractérisent les événements tels comme ľ inondation ou la chute de la Bourse. Une prédiction qu'on petit observer de la dichotomie proposée incertitude/risque, c'est que ľ assurance, qui concerne le risque, doit laisser de place aux réligions et aux autres systèmes de croyance qui invoquent ľ incertitude.

Notes: The paper results from interviews held among economists from Central and Eastern Europe. It tries to get an inside view on the profession under communist rule. As expected, the results depend upon period and country under analysis. Poland and Hungary did not lose contact with Western developments, while the Soviet Union and the GDR and also Czechoslovakia after 1968 isolated themselves completely. In Russia there was an own development in the sphere of optimal planning theory. In the GDR strict political control and adherence to dogmatism led to sterility. Reform thinking became stronger in the 1980s, with the exception of the GDR and Russia. The results are corroborated by the personal situation of the individual economist. Asked where they see the lasting contribution of economics under communism, most respondents are rather pessimistic: it is more the abortive practice of Soviet-type central planning which taught a lesson than the theoretical developments of the period.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGDie Studie ist das Ergebnis von Interviews, die unter Wirtschaftswissenschaftlern aus Mittel- und Osteuropa gehalten wurden. Sie sucht einen Blick von innen auf die Entwicklung einer Wissenschaft unter kommunistischer Herrschaft zu gewinnen. Das Resultat hängt von der jeweiligen Periode und dem jeweiligen Land ab. Polen und Ungarn haben den Kontakt zum Westen nicht verloren. Russland und die DDR, ebenso die CSSR nach 1968, haben sich dagegen vollständig isoliert. Russland kannte eine eigene Entwicklung in der Planungstheorie. In der DDR führten dagegen politische Kontrolle und Dogmatismus zur Sterilität. Mit Ausnahme dieserbeiden Länder wuchs das Reformdenken in den 80er Jahren stetig an. Die Ergebnisse spiegeln sich auch in der persönlichen Situation der einzelnen Wissenschaftler wider. Nach dem bleibenden Beitrag der Ökonomie unter dem Kommunismus befragt, zeigen sich die Antworten eher pessimistisch: nicht die theoretischen Errungenschaften der Periode sind lehrreich, vielmehr aber das abschreckende Beispiel des sowjetischen Zentralplansystems.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉL' article rend compte des résultats d'interviews réalisés auprès d'économistes des pays de l'Europe Centrale et Orientale. II présente une vision de l'intérieur sur le développement de la science économique sous le régime communiste. Les résultats dépendent de la période et du pays analyses. La Pologne et la Hongrie n'ont jamais perdu le contact avec la science économique occidentale, tandis que la Russie, l'Allemagne de l'Est et, après 1968, la Tchécoslovaquie s'en sont isolés complètement. Avec la théorie de la planification optimale, la Russie a connu son propre développement. En RDA, le contrǒle politique et le dogmatisme ont abouti à une stérilité théorique. À l'éxception de ces deux derniers pays, la pensée réformiste s'est renforcée continument au cours des années 80. Ces résultats se reflètent aussi dans la situation personnelle faite aux économistes. Quant a la contribution durable de la science économique sous le communisme, les réponses sont peu optimistes: ce ne sont pas tellement les développements théoriques qui survivront à la periode soviétique, mais plutöt (‘experience avortée de la planification centrale de type soviétique.

Notes: This paper presents the results of an overlapping-generations experiment on the individual choice between intergenerational transfers and savings. One dominant finding of our experiment is that if savings are possible individuals choose to (gradually) opt out of the intergenerational transfer system. In that case the average individual pay-offs are lower but their distribution among individuals is less volatile. This suggests that risk aversion is a driving force behind the decline of intergenerational transfers. The willingness to give to previous generations does not disappear completely, however. Moreover, the degree of cohesion between successive generations, measured by (lie correlation between current and past transfers does not diminish significantly after the introduction of (he savings option.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMIENEASSUNGDicser Artikcl präsentierl die ErgebnisseeinesOvcrlapping-Generations-Experitnents, indent sich die Tcilnehmer zwisehen tnlergenerationalcn Transfers und Sparen entscheiden mussten. Eines der Hauptergcbnisse besteht darin, dass die Einführung der Mögliehkeit zur individuellen Zukunfts-vorsorge durch Sparen zu einer (allmählichen) Zurückdrängung von intergencrationalen Transfers führt. Im Fall des Sparens isl die durehschnittliche individuclle Auszahlung zwar geringer, dafür aber weniger unsieher. Die Zurückdrangung intergenerationaler Transfers lässt sich dahcr durch Risikoaversion erklären. Dennoch verschwindct die Bereitschaft, an die vorausgehende Generation abzugeben, nicht völlig. Ausserdein vennindert sich die Stärke des Zusatnnienhalts zwisehen aufcinanderlolgcnden Generalionen, getnessen durch die Korrelation zwisehen gegenwärtigen und früheren Transfers, nicht wesentlich durch die Einführung der Mögliehkeit des Sparens.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉLe papier présente des résultats expérimentaux sur les choix individuels entre transferts inter-génération et épargnc. Un des résultats principaux est que s'il est possible d'épargncr, alors (progressivement) les agents passent du système de transfer! inter-générationnelausystème d'épargne. Dans de cas le payoff moyen des agents est plus faible mais la distribution des payoffs est inoins volatile. Ceei suggère que l'aversion pour le risque est l'une des prineipales causes du déclin des transferts intergénération. Cependant, les transferts inter-génération ne disparaissent pas totalement. De plus, le degré de cohesion entre les génération successives, mesuré par la corrélation entre les transferts présents et passés, ne diminue pas significativemenl apres l'introduction de la possibilityé d'épargncr.

Notes: This paper investigates spatial disparities in unemployment in three Member States of the EU. It attempts to identify the factors responsible for the persistence of regional unemployment disparities in Germany, Italy and the UK during 1984-94. The empirical results indicate that a substantial proportion of the variation in unemployment rates between NUTS2 level regions can be explained by regional disparities in three key variables: unit labour costs, the industry mix and employment density. The findings are consistent with the view that regional unemployment disparities are explained primarily by regional disparities in economic competitiveness.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNODieser Artikel untersucht die räumlichen Unterschiede in der Höhe der Arbeitslosigkeit in drei Mitgliedsstaaten der EU. Er basiert auf dem Versuch, die Faktoren zu bestimmen, die im Zeitraum zwischen 1984 und 1994 für die Persistenz von regionalen Unterschieden der Höhe der Arbeitslosigkeit in Deutschland, Italien und Grossbritannien verantwortlich waren. Die empirischen Ergeb-nisse zeigen, dass ein wesentlicher Teil der Unterschiede in der Höhe der Arbeitslosigkeit zwischen NUTS2 Regionen durch eine regional unterschiedliche Ausprägung von drei wichtigen Variablen erklärt werden kann: Lohnstückkosten, Wirtschaftsstruktur und Zahl der Arbeitsplätze pro Quadratkilometer. Die Ergebnisse bestätigen die Ansicht, dass die regional unterschiedlich hohe Arbeitslosigkeit hauptsächlich durch Unterschiede der regionalen Wettbewerbsfähigkeit zu cr-klüren ist.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉCe document examine les disparités géographiques du chǒmage dans trois États membres de l'Union Européenne. Nous essayerons d'identifier les facteurs responsables de la persistance des disparités en chǒmage régional en Ailemagne, en Italie el au Royaume-Uni pendant la période 1984-94. Les résultats empiriques indiquent qu'une proportion importante de la variation du taux de chǒmage entre les régions de la catégorie NUTS2 peut s'expliquer par des disparités régionales en trois variables prépondérantes: le coǔt unitaire d'emploi, la structure industrielle et la densité d'emploi. Les résultats coïncident avec l'avis que les disparités du chǒmage régional s'expliquent surtout par les disparités régionales en compétitivitééconomique.

Notes: In many settings, economic efficiency in law enforcement appears to require differential enforcement of the law. For example, as shown in the paper, crime prone populations warrant stronger sanctions than less crime prone populations if costly sanctions are to be meted out in an efficient manner. However, narrow economic analysis of efficient sanctions attributes an efficiency to modern democratic governments which can not be easily justified by analysis or experience. This paper demonstrates that constraining majority coalitions to write laws consistent with the principle of equal protection generally yields more desirable outcomes than obtained when majority coalitions are permitted to discriminate in an arbitrary manner. The efficiency case for equality before the law is based on political considerations rather than economic ones per se.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGDas Kriterium der ökonomischen Effizienz bei der Durchsetzung von Recht scheint in vielen Situationen eine differenzierende Durchsetzung des Rechts zu erfordern. Wie in diesem Artikel ge-zeigt werden kann, können beispielsweise für mehr zu Verbrechen neigende Bevölkerungsteile härtere Strafen gerechtfertigt sein, als für weniger zu Verbrechen neigende Bevölkerungsteile, wenn die mit hohen Kosten verbundene Bestrafung von Verbrechen effizient eingesetzt werden soil. Allerdings schreibt die ökonomische Analyse von effzienten Strafen modernen demokratischen Regierungen eine Effizienz zu, die durch Analyse oder Erfahrung nur schwer zu bestätigen ist. Dieses Papier zeigt nämlich, dass wünschenswertere Ergebnisse zu erzielen sind, wenn man Mehrheitskoalitionen dazu zwingt, Gesetze zu schreiben, die mit dem Prinzip der Gleichheit vor dem Gesetz übereinstimmen, als wenn man Mehrheitskoalitionen erlaubt, auf willkürliche Weise zu diskriminieren. Im Ergebnis lasst sich daher feststellen, dass die Effizienzargumente im Hinblick auf die Gleichheit bzw. Ungleicheit vor dem Gesetz lediglich auf politischen Überlegungen beruhen, aber nicht auf ökonomischen.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉDans beaucoup de situations, l'éfficience économique de l'application de la loi semble exiger une application différenciée. Par exemple, comme il est expliqué dans l'article, des lois plus restrictives peuvent ětre appliqués pour une partie de la population étant plus incliné a la criminalité que pour des parties moins inclinées, si les coǔts élevés de l'application de la loi doivent ětre utilisés avec éfficience. Pourtant, l'analyse économique sur la punition éfficiente attribue aux gouvernements démocratiques modernes une éfficience qui ne peut pas ětre justifyé aisément par l'analyse et l'expérience. Cet article montre que des résultats meilleures peuvent ětre atteints si des coalitions majoritaires peuvent ětre contraintes à concevoir des lois qui sont consistents avec le principe de la protection égale devant la loi, que si une coalition majoritaire permet de discriminer une partie de la population de manière arbitraire. L'éfficience du principe de l'égalité devant la loi est basé sur des considérations politiques, et non sur des considérations économiques.

Notes: Argy, Victor and Leslie Stein (1997). The Japanese Economy. Basingsto-ke/London: Macmillan. 379 pp. £47.50. ISBN 0-333-6756-5. £17.50. ISBN 0-333-67566-5.Balasubramanyam, V. N. and D. Greenaway (eds.) (1996). Trade and Development. Essays in Honour of Jagdish Bhagwati. Basingstoke/London: Macmillan. 217 pp. £45.00. ISBN 0-333-65616-4.Blejer, Mario I. and Teresa Ter-Minassian (eds.) (1997). Macroeconomic Dimensions of Public Finance. Essays in Honour of Vito Tanzi. London/New York: Routledge. 506 pp. £65.00. ISBN 0-415-14111-7.Blejer, Mario I. and Teresa Ter-Minassian (eds.) (1997). Fiscal Policy and Economic Reform. Essays in Honour of Vito Tanzi. London/New York: Rout-ledge. 305 pp. £60.00. ISBN 0-415-13739-X.Brömmelhörster, Jörn and John Frankenstein (eds.) (1997). Mixed Motives, Uncertain Outcomes. Defense Conversion in China. Boulder: Lynne Rienner Publishers. 275 pp. $ 55.00. ISBN 1-555-87710-9.Constanza, Robert, Charles Perrings and Cutler J. Cleveland (eds.) (1997). The Development of Ecological Economics. Cheltenham, UK/Brookfield, USA: Edward Elgar. 777 pp. £160.00. ISBN 1-85898-386-X.Craig, Lee A. and Douglas Fisher (1997). The Integration of the European Economy, 1850-1913. Basingstoke/London: MacMillan Press. 327 pp. ISBN 0-333-58036-2.Davies, Stephen and Bruce Lyons (1996). Industrial Organization in the European Union. Structure, Strategy and the Competitive Mechanism. Oxford: Clarendon Press. 287 pp. £40.00. ISBN 0-19-828973-1.Fratianni, Michele and Franco Spinelli (1997). A Monetary History of Italy. Cambridge: Cambridge University Press. 305 pp. £40.00. ISBN 0-521 -44315-6.Gandolfo, Giancarlo (1996). Economic Dynamics, 3rd ed. Berlin/Heidelberg/New York/London: Springer. 610 pp. DM 178.-. ISBN 3-540-60988-1.Garfinkel, Michelle R. and Stergios Skaperdas (eds.) (1996). The Political Economy of Conflict and Appropriation. Cambridge/New York/Melbourne: Cambridge University Press. 182 pp. $ 49.95. ISBN 0-521-56063-2.Kemp, René (1997). Environmental Policy and Technical Change. A Comparison of the Technological Impact of Policy Instruments. Cheltenham, UK/Brookfield, USA: Edward Elgar. 360 pp. £55.00. ISBN 1-85898-506-4.Klamer, Arjo (ed.) (1996). The Value of Culture. On the Relationship between Economics and Arts. Amsterdam: Amsterdam University Press. 243 pp. £21.95. ISBN 90-5356-218-4.Llau, Pierre (1996). Economie financeère publique. Paris: Presses Universitai-res de France. 546 pp. 168 FF. ISBN 2-13-047774-7.Mueller, Dennis C. (ed.) (1997). Perspectives on Public Choice. A Handbook. Cambridge: Cambridge University Press. 672 pp. $79.95. ISBN 0-521-55377-6 (he.). $ 29.95. ISBN 0-521-55654-6 (pbk.).Pritzl, Rupert F.J. (1997). Korruption und Rent-Seeking in Lateinamerika. Zur Politischen Ökonomie autoritärer politischer Systeme. Baden-Baden: Nomos. 318 S. ISBN 3-7890-4692-2.Schmidt-Trenz, Hans-Jörg (1996). Die Logikkollektiven Handelns bei Delegation. Tübingen: J.C.B. Mohr (Paul Siebeck). 293 S. ISBN 3-16-146607-1.Xepapadeas, Anastasios (ed.) (1996). Economic Policy for the Environment and Natural Resources. Techniques for the management and Control of Pollution. Cheltenham, UK/Brookfield, USA: Edward Elgar. 245 pp. £59.95. ISBN 1-85898-413-0.

Notes: After overall entry deregulation, regulation of market power can only be justified in local telecommunication networks as long as they constitute monopolistic bottlenecks. Technical progress leads to a gradual disappearance of monopolistic bottlenecks, pointing out the large potential for economically efficient phasing out of sector-specific regulation. In contrast, all forms of asymmetric regulation containing an intrinsic bias towards some firms or technologies have a strong tendency towards overregulation. The new telecommunications laws in Germany and Switzerland are shown to be prominent examples of asymmetric regulatory frameworks. Since the new telecommunications law in Switzerland is less restrictive and more transparant than its German counterpart, it seems to be more suitable to tackle the potential for phasing out sector specific regulation in telecommunications.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGNach einer umfassenden Marktoffnung ist eine Marktmachtregulierung in der Zukunft lediglich noch in Ortsnetzen gerechtfertigt, solange diese monopolistische Engpassbereiche darstellen. Der technische Fortschritt in Ortsnetzen führt allerdings allmahlich zu einer Auflösung dieser Engpassbereiche und schafft dadurch ein zunehmendes Potential für die Abschaffung sektorspezifischer Regulierungseingriffe. Demgegenüber beinhalten alle Formen asymmetrischer Regulierung eine immanente Verzerrung zugunsten spezieller Firmen oder Technologien und damit einhergehend eine starke Tendenz zur Uberregulierung. Die neuen Telekommunikationsgesetze in Deutschland und in der Schweiz stellen bedeutende Beispiele für asymmetrische Regulierungsrahmen dar. Allerdings erweist sich das neue schweizerische Telekommunikationsgesetz als weniger restriktiv und transparenter als sein deutsches Gegenstück. Es ist daher zu erwarten, daß das zunehmende Potential für ein ‘phasing out' sektorspezifischer Regulierungseingriffe in der Schweiz rascher ausgeschöpft wird als in Deutschland.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉA près une ouverture entière du marché de télécommunication une régularisation de la domination du marché ne sera justifiée à l'avenir que dans les réseaux locaux aussi longtemps qu'ils constituent des goulots d'étranglement monopolistiques. Le progrès technique dans les réseaux locaux mène peu à peu à la disparition des ces goulots détranglement en créant ainsi un potentiel croissant de suppression de la régularisation sécteur-spécifique. Par contre, toutes les formes de régularisation asymétrique contenant une distorsion immanente au profit de certaines firmes ou de certaines technologies ont une forte tendance à la sur-régularisation. Les nouvelles lois de télécommunication en Allemagne et en Suisse sont des exemples importants d'encadrements asymétriques de régularisation. Cependant, la nouvelle lot de télécommunication suisse se montre moins restrictive et plus transparente que la loi respective en Allemagne. Par conséquent, l'on peut s'attendre à ce que le potentiel croissant de suppression de régularisations sécteur-spécifiques sera épuisé plus vite en Suisse qu'en Allemagne.

Notes: Tax evasion has been mainly studied as a problem of choice under uncertainty; like any portfolio manager, the taxpayer has to allocate her/his fixed gross income between two assets a risky asset, tax evasion, and a safe asset (with a zero return), tax payment. As suggested by the portfolio theory, the taxpayer's choice will be affected by her/his preferences — mainly by her/his attitude towards risk-taking — and by the return on the risky asset determined by the tax structure, which includes both the tax rate and the penalties in the case of evasion However, the pure gamble model appears unsatisfactory on various grounds. Among these and most importantly for our purpose, it neglects the psychological aspects of the decision to evade tax because it rules out any feeling of shame about evading or being detected and punished, and it ignores any intrinsic pleasure from successful evasion In other words, the pure gamble model does not take full account of the moral constraints involved in the tax evasion decision. The main objective of the experiment presented here was therefore to investigate the role played by moral constraints in determining the decision to evade taxes. The experimental evidence supports the thesis that the taxpayer's decisional process involves not only monetary elements but also psychological and moral factors.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGDie Steuerhinterziehung wurde bisher überwiegend als Problem von Entscheidungen unter Unsicherheit untersucht Wie jeder Portfoliomanager muss auch der Steuerzahler sein Bruttoeinkommen zwischen zwei Anlageformen verteilen eine risikoreiche Anlageform. Steuerhinterziehung, und eine sichere Anlageform (ohne Gewinn), Steuerzahlung. Nach der Portfoliotheorie wird die Entscheidung des Steuerzahlers von seinen Praferenzen beeinflusst — vor allem von seiner Risiko-bereitschaft — und von der Gewinnaussicht der risikoreichen Anlageform, die vom Steuersystem abhangt, d.h. vom Steuersatz und den Strafen bei Steuerhinterziehung. Dieses Lotteriemodell ist jedoch aus mehreren Grunden unbefriedigend: es vernachlässigt die psycholgischen Aspekte der Steuerhinterziehung, weil es jegliches Schamgefühl bei der Steuerhinterziehung bzw. der Entdeckung und Bestrafung ausschliesst und ein intrinsisches Vergnugen bei erfolgreicher Steuerhinterziehung ignoriert. Das Lotteriemodell zieht also nicht in Betracht, dass moralische Restriktionen die Entscheidung zur Steuerhinterziehung beeinflussen konnten Das hier vorgestellte Experiment wollte daher in erster Linie untersuchen, welche Rolle moralische Restriktionen bei der Entscheidung zur Steuerhinterziehung spielen. Die Ergebnisse des Experiments bestatigen die Hypothese, dass der Entscheidungsprozess des Steuerzahlers nicht nur durch monetare Elemente beeinflusst wird, sondern auch durch psychologische und moralische Faktoren.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉL'évasion fiscale a été principalement étudiée en tant qu'un problème de choix dans des conditions d'incertitude, comme n'importe quel gestionnaire de portfolio, le contribuable doit répartir son revenu brut fixe entre deux actifs un actif risqué, l'évasion fiscale, et un actif sǔr (avec un taux d'intérét zéro), le payement des taxes. Comme suggéré par la théorie du portfolio, le choix du contribuable sera affecté par ses préférences — principalement par son attitude vis-à-vis du risque — et par le bénéfice déterminé par la structure fiscale qui inclut à la fois le taux de taxation et les pénalités prévues en cas d'évasion Cependant, le modèle pur de jeu apparait insatisfaisant pour plusieurs rasisons Parmi celles-ci, le modèle néglige les aspects psychologiques de la décision, limitation spécialement importante pour notre objectif, puisqu'il écarte tout sentiment de honte associé à la découverte de l'évasion et à la punition ou encore il ignore le plaisir découlant d'une évasion fiscale réussie. En résumé, le modèle pur de jeu ne prend pas pleinement en compte les contraintes morales qui influencent la décision. L'objectif principal de l'expérimentation présentée ici était d'analyser le rǒle joué par les contraintes morales dans la prise de décision d'évasion fiscale. Les résultats confirment l'hypothèse que le processus décisionel du contribuable dépend non seulement des aspects financiers mais également des facteurs psychologiques et moraux.

Notes: This paper shows two points: (1) there is a statistically significant positive relationship between the real value of the agricultural minimum wage and the level of agricultural output in Morocco, for eight important crops; (ii) the latter may be explained using a theoretical model where the productivity of the laborers depends on their consumption level, and where wage incomes are shared among family members to fund consumption. The Nash equilibrium is then inefficient.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGDieser Artikel zeigt zweierlei: a) Für acht Feldfnichte existiert eine statistisch sigrufikante Beziehung zwischen realem Mindestlohn und Produktionsniveau in der marokkanischen Landwirtschaft; b) Diese Beziehung lasst sich mit einem theoretischen Modell erklären. Darin hangt die Produktivitat der Arbeiter von ihrem Lebensstandard ab. Zur Konsumfinanzierung werden die Lohneinkunfte zwischen den Mitgliedern der Familie aufgeteilt. Das Nash-Gleichgeèicht ist somit ineffizient.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉCet article montre deux choses: (a) il y a une relation statistiquement significative entre la valeur réelle du salaire minimum agricole et le niveau de la production agricole au Maroc, pour huit cultures importantes; (b) celle-ci peut s'expliquer au moyen d'un modèle théorique où la productivité des travailleurs dépend de leur niveau de consommation, et où les revenus salariaux sont partagés entre les membres de la famille pour financer la consommation. L'équilibre de Nash est alors inefficient.

Notes: This paper reports the results of a comparison of employment adjustment in Japan, the United States and four major EC countries. Output and real wages are used in explaining the optimal employment level and change in employment. Short- and long run responses to alterations of the exogenous variables are estimated and compared. Surprisingly, Germany has a quite rapid adjustment of labor while France and Italy show a much slower adjustment pattern. Even in comparison with the United States. Great Britain demonstrates the fastest adjustment to changes in the economic environment. By far the slowest adjustment pattern is realized in Japan. Overall the difference between the US and Europe seems not to be too large and European labor markets are not as sclerotic as occasionally assumed.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASUNGDieser Artikel gibt die Ergebnisse eines Vergleichs der Beschäftigungsanpassung in Japan, den Vereinigten Staaten und den vier wichtigsten EU-Landern wieder. Das Produktionsniveau und der Reallohn sind die erklarenden Variablen für das optimale Beschaftigungsniveau wie auch Veranderungen der Beschäftigung. Es werden kurz- und langfnstige Beziehungen zwischen den exogenen und der endogenen Vanablen geschatzt und verglichen Uberraschenderweise hat Deutschland eine relativ rasche Beschaftigungsanpassung, während Frankreich und Italien eine viel langsamere Anpassung aufweisen. Großbntannien hat auch im Vergleich zu den USA die schnellste Reaktion auf Veränderungen der ökonomischen Umwelt. Das bei weitem inflexibelste Anpassungsverhalten wird für Japan registriert. Zusammenfassend scheinen die Unterschiede zwischen den Vereinigten Staaten und Europa nicht so groß und der europaische Arbeitsmarkt nicht so sklerotisch zu sein wie erwartet.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉCet article présente les résultats d'une comparaison de la vitesse d'adaptation de l'emploi au Japon, aux Etats-Unis et dans les quatre pays les plus importants de l'UE. Le niveau de l'emploi optimal ***ainsi que les variations de l'emploi sont expliquées par le niveau de production et les salaires réels. Les variations à court et long terme des changements des variables exogènes ont été estimés et comparés. Étonnamment, l'Allemagne a une vitesse d'adaptation de l'emploi relativement rapide par rapport à celles de la France et de l'Italie. L'Angleterre montre měme, en comparaison avec les Etats-Unis, une plus grande flexibilité envers les modifications de l'environnement économique. L'adaptation la plus lente est observée au Japon. Pour conclure les différences concernant la vitesse d'adaptation de l'emploi entre les Etats-Unis et l'Europe ne semblent pas si grandes et les marchés de travail européens sont moins sclérosés que ce que l'on attendait.

Notes: Agénor, Pierre-Richard and Peter J. Montiel (1996). Development Macroeconomics.Baldwin, John R. (1995). The Dynamics of Industrial Competition.Barnet, William A., Hervé Moulin. Maurice Salles and Norman J. Schoficld (eds.) (1995). Social Choice, Welfare, and Ethics.Benassi, Corrado, Alessandra Chirco, Caterina Colombo (1994). The New Keynesian Economics.Eatwell, John et al. (1995). Transformation and Integration.Führer, Karl Christian (1995). Mieter, Hausbesitzer, Staat und Wohnungs-markt.Haq. Mahbuh ul (1995). Reflections on Human Development.Hartwig, Karl-Hans und Ingo Pies (1995). Rationale Drogenpolitik in der Demokratie.Hausman, Daniel M. and Michael S. McPhcrson (1996). Economic Analysis and Moral Philosophy.Hufbauer, Gary Clyde, Carol Gabyzon (1996). Fundamental Tax Reform and Border Tax Adjustments.Judge, Paramjit S. (1994). A study of Formation of an Ethnic Community.Kleindorfer, Paul L., Howard C. Kunreuther and David S. Hong (eds.) (1996). Energy, Environment and the Economy.Lombardini, Siro (1996). Growth and Economic Development.Penz, Reinhard und Holger Wilkop (Hrsg.) (1996). Thorstein Veblens evoluto-rische Ökonomik.World Bank (1996). World Development Report 1996.

Notes: A discrete time, discounted utility model with a finite horizon is analyzed. Utility is separable and additive in the natural logarithms of the choice variables, consumption and leisure, and an exogenous ‘memory' series. Happiness is defined as the discounted value of the utility over the remaining lifespan. Simulations of the model show how happiness grows as the high consumption years get closer, peaks, then declines in later life as the remaining lifespan shortens, even though year by year utility may continue to rise. Simulations also show how the peak year for happiness depends on the subjective, personal discount rate, the rate of wage growth, the effect of a liquidity constraint, the effect of memories, and other parameters in the model. The model also illustrates those aspects of the life cycle characterized by the ‘slackers’, the ‘mid-life crisis’, and the ‘golden years’.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGEin diskretes, abdiskontiertes Nutzenmodell mit einem endlichen Zeithorizont wird analysiert. Nutzen wird als zerlegbar und additiv in den natürlichen Logarithmen der Wahlvanablen Konsum und Freizeit und in den exogenen Zeitreihen für ‘Erinnerungen’ angenommen. Gluck ist definiert als abdiskontierter Wert des Nutzens der verbleibenden Lebenszeit. Simulationen zeigen, wie das Glück bei der Annäherung an die Jahre erhöhten Konsums ansteigt, einen Hohepunkt erreicht, um dann in der verbleibenden Lebenszeit wieder abzunehmen, obwohl der Nutzen Jahr fur Jahr weiterhin zunehmen kann. Die Simulationen zeigen auch, wie der Höhepunkt des Glücks vom persönlichen Diskontsatz, der Zuwachsrate des Einkommens, Liquiditatsbeschrankungen, Erinnerungen und anderen Parametern abhangt. Das Modell veranschaulicht aber auch jene Aspekte der Lebenszeit, die üblicherweise als ‘Slackers’, ‘Mid-life Crisis' und ‘Goldene Jahre’ bezeichnet werden〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉAnalyse d'un modèle d'utilité d'escompte à temps discret et à horizon limité. L'utilité est séparable et additive dans les logarithmes naturels des variables de choix, la consomption et les loisirs, et une série exogène de ‘mémoire’. On définit le bonheur comme la valeur d'escompte de l'utilité pendant la durée de la vie qui reste. Des simulations du modèle montrent comment le bonheur s'augmente au fur et à mesure que les année de grande consomption s'approchent, atteint son comble, puis baisse dans la dernière partie de la vie pendant que la durée de la vie qui reste se réduit, quoique, année par année, l'utilité puisse continuer à s'augmenter. Les simulations montrent aussi comment l'année du point culminant de bonheur dépend du taux d'escompte subjectif et personnel, du taux d'augmentation de salaire, de l'effet d'une contrainte de liquidité, de l'effet des souvenirs, et d'autres paramètres du modèle. Le modèle illustre aussi les aspects du cycle de vie caractérisés par les fainéants, la crise de ‘mid-life’ et les années ‘dorées’.

Notes: Boss, Alfred, Claus-Friedrich Laaser, Klaus-Werner Schatz et al. (1996). De-regulierung in Deutschland. Eine empirische Analyse. Tübingen: J.C.B. Mohr (Paul Siebeck). 422 S. DM 148.00. ISBN 3-16-146593-8.Caves, Richard E. (1996). Multinational Enterprise and Economic Analysis, 2nd Ed. Cambridge/New York/Melbourne: Cambridge University Press. 322 pp. £14.95 (paper). ISBN 0-521-47858-8. $ 40.00 (hard). ISBN 0-521-47265-2.Cencini, Alvaro and Mauro Baranzini (cds.) (1996). Inflation and Unemployment. Contributions to a new macroeconomic approach. London/New York: Routledge. 192 pp. £40. ISBN 0-415-11822-0.Daly, Herman E. (1996): Beyond Growth. The Economics of Sustainable Development. Boston: Beacon Press. 253 pp. Can £40.95. ISBN 0-8070-4708-2.Faucheux, S., D. Pcarce and J. Proops (eds.) (1996). Models of Sustainable Development. Cheltenham, UK and Brookllcld, USA: Edward Elgar. 365 pp. £49.95 ISBN 1-85898-269-3.Hamlin, Alan P. (ed.) (1996). Ethics and Economics. Vol. I and Vol. II. Cheltenham, UK/Brookfield, USA: Edward Elgar. 625 pp. and 514 pp. £230.00. ISBN 1-85278-814-3.Harrop, Jeffrey (1996). Structural Funding and Employment in the European Union. Financing the Path to Integration. Cheltenham, UK/Brookfield, USA : Edward Elgar. 192 pp. £49.95. ISBN 1-85898-219-7.Irwin, Douglas A. (1996). Against the Tide. An Intellectual History of Free Trade. Princeton: Princeton University Press. 165 pp. $ 29.95. ISBN 0-691-01138-9.Kirkpatrick, C. and J. Weiss (eds.) (1996). Cost-Benefit Analysis and Project Appraisal in Developing Countries. Cheltenham, UK/Brookfield, USA: Edward Elgar. 321 pp. £49.95. ISBN 1-85898-346-0.Amitrajeet A. Batabyal, Assistant Professor Utah State University, Dept. of Economics Logan, UT 84322-3530 (USA)Mayer, Achim (1996). Fegefeuer und Bettelorden: Päpstliches Marketing im 13. Jahrhundert. Ein Beitrag zur Analyse der Unternehmensgeschichte der katholischen Kirche unter Einsatz der Franchisetheorie. Marburg: Metropolis. 211 S. ISBN 3-89518-096-3.Stefan Schaltegger, Assistenzproressor Universitat Basel, Wirtschaftswissenschaftliches Zentrum (WWZ) Petersgraben 51, CH-4003 Basel (Switzerland)Paul, E. F., F. D. Miller and J. Paul (eds.) (1996). Contemporary Political and Social Philosophy. Cambridge/New York/Melbourne: Cambridge University Press. 240 pp. £14.95. ISBN 0-521-48399-9.Amitrajeet A. Batabyal, Assistant Professor Utah State University, Dept. of Economics Logan, UT 84322-3530 (USA)Schulz, Giinther (1994). Wiederaufbau in Deutschland. Die Wohnungspolitik in den Westzonen und der Bundesrepublik von 1945 bis 1957. Düsseldorf: Droste. 405 S. DM 58.-. ISBN 3-7700-0975-4.Tietzel, Manfred (1995). Literaturökonomik. Tübingen: J.C.B. Mohr (Paul Siebeck). 283 S. ISBN 3-16-146425-7.Van Parijs, Philippe (1995). Real Freedom for All. What (if Anything) Can Justify Capitalism? Oxford, UK: Oxford University Press. 330 pp. $ 35.00. ISBN 019-8279051.Wolf, Susanna (1996). Bcgrcnzlcr Erfolg der Lome-Abkommcn. Einc cmpiri-schc Untersuchung dcr Wirkungen dcr EU-Zollpraferenzcn aul'dcn Handel der AKP-Slaaten. Frankfurt am Main, Berlin u.a.: Peter Lang. 250 S. DM 79.00. ISBN 3-631-30856-6.

Notes: Since the sixties, the discussion whether democracy is a precondition for or a result of economic growth has not yet been finished. In this paper a comparative institutional analysis of the relative performance of direct and representative democratic decision making in the Swiss economy is undertaken using a cross section of the 26 Swiss states in 1989 and pooled cross section time series data for the states from 1982 to 1993. The empirical results and robustness tests support the hypothesis that the stronger control of the representatives by the voters due to obligatory and optional referenda leads to better economic performance.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGSeit den sechziger Jahren diskutieren Sozialwissenschaftler darüber, welche Auswirkungen De-mokiatie auf das wirtschaftliche Wachstum eines Landes hat. In diesem Aufsatz wird der Einfluss direkt- und repräsentativ-demokratischer Entscheidungsprozesse in einer vergleichenden institutionellen Analyse unter Verwendung von kantonalen Querschnittsdaten für 1989 und gepoolten Querschnitts- und Zeitreihendaten für den Zeitraum von 1982 bis 1993 untersucht. Die empirischen Ergebnisse und unterschiedliche Robustheitstests stützen die Hypothese, dass die stärkere Kontrolle der Repräsentanten durch die Stimmbürger mit Hilfe von obligatorischen und fakultativen Referenden zu einer relativ besseren wirtschaftlichen Leistungsfähigkeit führt.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉLa question de savoir si les institutions démocratiques ont un effet positif ou negatif sur le développement économique est discutée depuis les années soixante à soixante-dix. La présente étude économétrique compare l'effet de différents types d'institutions démocratiques (démocratic représentative et directe) sur le développement économique. A cette fin nous analysons le niveau de développement économique des cantons suisses en fonction de leurs institutions politiques. Les résultats empiriques, qui se révèlent robustes dans différents tests, appuient l'hypothèse qu'un contrǒle plus étroit des élus par le référendum facultatif ou obligatoire conduit à une plus grande performance économique.

Notes: Are modern democracies capable of preserving the constitution of liberty and capable of preserving the natural basis of human existence in the long-run? The achievement of these aims requires political actions toward fundamental changes in the life of modern societies. The respective political actors have to develop and to sustain long-term constitutional and ecological interests. Can these actors be conceived as homines oeconomici? Within public choice there have been important attempts to derive long-term interests on the basis of homo oeconomicus. These attempts have led, however, to theoretical difficulties. To develop a solution we introduce the notion of homo politicus. Homo politicus is concerned with the common search for the general interest of a political community which in traditional philosophy is called ‘justice’. The concepts of homo oeconomicus and homo politicus are not mutually exclusive alternatives, but dimensions of human behaviour. Neither of them can be empirically observed in its pure form. We argue that we need a combination of both concepts to understand political phenomena. Thereby we seek to contribute to a theoretical basis which allows the derivation of the constitutional interest and the ecological interest.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGKönnen moderne demokratische Rechtsstaaten langfristig eine freiheitliche Verfassung bewahrcn und den Fortbestand der natürlichen Lebensgrundlagen sichern? Die Verwirklichung dieser beiden Ziele macht politische Handlungen erforderlich, die zu fundamentalen Änderungen in der Lebensweise moderner Gesellschaften führen. Die politisch Handelnden müssen hierzu von langfristigen Interessen an einer freiheitlichen Verfassung (konstitutionelles Interesse) und am Fortbestand der natürlichen Lebensgrundlagen (ökologisches Interesse) geleitet wcrden. Können diese politisch Handelnden angemessen als homines oeconomici aufgefasst werden? In der Public Choice sind bedeutsame Versuche unternommen worden, Langzeitintcressen auf der Basis des homo oeconomicus abzuleiten. Dabei ergaben sich indes beträchtliche konzeptionelle Probleme. Um eine Lösung denkbar zu machen, führen wir den Begriff des homo politicus ein. Der homo politicus ist der Mensch, insofern er sich gemeinsam mil andern in einem Handlungsfeld betätigt, in dem es um das allgemeine Interesse einer Gesellschaft, in der philosophischen Tradition: um die ‘Gerechtig-keit’, geht. Die Konzepte des homo oeconomicus und des homo politicus schliessen sich nicht gegenseitig aus, sondern verweisen auf verschiedene Dimensionen menschlichen Verhaltens, die in ihrer Reinform empirisch nicht beobachtet werden. Wir sind der Ansicht, dass die Untersuchung politischer Phänomene vielfach eine Kombination beider Konzepte erforderlich macht. Unser Ansatz versteht sich als Beitrag zu einer theoretischen Grundlegung, die die Ableitung des konstitutionellen und des ökologischen Interesses ermöglichen soll.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉEst-ce que les démocraties modernes sont capables de préserver la constitution de la liberté et en měme temps la base naturelle de l'existence humaine? Pour attcindre ces buts, il faut des actions politiques pour des changements fundamentals dans les societés modernes. II faut que les acteurs politiques développent et soutiennent un interět constitutionel et un interět ěcologique à long terme. Est-ce qu'il est possible que ces acteurs soient dénotés comme homines oeconomici? Dans la théorie de public choice il y avait des essais importants de dériver des interets à long terme en base de l'homo oeconomicus. Mais ces essais ont menés à de graves difficultés théoretiques. En adressant ces problèmes nous introduisons la notion homo politicus. Homo politicus est concernéà l'action politique. Cette action consiste en la recherche de 1 interět général d'une communité politique que l'on appelle ‘justice’. Les conceptes de homo oeconomkus et homo politicus ne s'exclusent pas mais sont des dimensions differents de la manière d'agir humaine. Aucune ne peut ětre observéc dans sa forme pure. Nous argumentons que souvent l'on a besoin d'une combinaison des ces deux concepts pour bien comprendre des phénomènes politiques. Avec cet article nous essayons de contribuer à la base théorique qui permet la derivation de l'interět constitutionel et de l'interět écologique.

Notes: The idea of deregulating shopping hours brings strong opposition from many groups in the society. Surprisingly, even many consumers oppose deregulation. The paper rationalizes this behavior by considering heterogeneous consumers who differ in their earnings abilities. If a majority of families has two income earners, long opening hours become essential and the regulation of shopping hours tends to be eliminated. If most families are single income households, the regulation may be imposed in order to keep prices low. Taking the repercussions on the labor supply decision into account, multiple equilibria can be explained.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGDie Liberalisierung der Ladenöffnungszeiten ruft Widerstand in verschiedenen Gesellschaftsgrup-pen hervor. Überraschenderweise sprechen sich sogar Konsumenten oft gegen eine Liberalisierung aus. Der Aufsatz erklärt dieses Verhalten, indem auf die Heterogenität der Konsumenten hinsichtlich ihres Erwerbsverhaltens abgestellt wird. Überwiegen im politischen Entscheidungsprozess Doppelverdienerhaushalte, für die längere Öffnungszeiten wichtig sind, wird eine bestehende Regulierung tendenziell eliminiert. Falls jedoch Haushalte mit nur einem Erwerbstätigen dominieren, wird die Regulierung aufrechterhalten, urn die Konsumentenpreise niedrig zu halten. Berücksichtigt man die Rückwirkungen unterschiedlicher Regulierungen auf die Arbeitsangebots-entscheidung, so lassen sich multiple Gleichgewichte erklären.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉLa libéralisation des heures d'ouverture des magasins se heurte à un mouvement d'opposition au sein de différents groupes sociaux. Surprenant est que měme des consommateurs se prononcent contre la libéralisation. Cet essai explique ce comportement en considérant l'hétérogénéité des consommateurs quant à leur possibilityé de revenus. Si les foyers, alimentés par deux salaires, pour lesquels un prolongement des heures d'ouverture est important, forment la majorité dans le processus de décision politique, on tendra àéliminer le règlement en vigueur. Par contre, au cas où les foyers avec un seul salaire dominent, on conservera le règlement pour maintenir les prix bas. Prend on en compte les effets des différents règlements sur la décision de l'offre de l'emploi, on peut ainsi mettre en évidence de multiples équilibres.

Notes: This essay considers the Soros critique of the epistemological and analytical foundations underlying theories of rational expectations equilibria and efficient markets. Similarities between Soros and Keynes are found. It is pointed out that Soros is guarded rather than nihilistic about the possibilities of economic knowledge, and developments in economic analysis that resonate with the Soros view are discussed.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGDieser Aufsatz unterwirft die Kritik von Soros an den epistomologischen und analytischen Grundlagen, die den Theorien der rationalen Erwartungen und effizienter Märkte zugrunde liegen, einer näheren Betrachtung. Dabei werden Áhnlichkeiten zwischen Soros und Keynes deutlich. Es kann gezeigt werden, dass Soros den Anwendungsmöglichkeiten ökonomischen Wissens nicht nihilistisch gegenübersteht, sondern sich von ihnen leiten lässt. Darüber hinaus werden Entwick-lungen der ökonomischen Analyse diskutiert, die mit der Meinung von Soros übereinstimmen.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉCet essai considère la critique Sorosienne des bases épistémologiques et analytiques des théories des équilibres des prévisions rationnelles et des marchés efficients. Des similitudes entre Soros et Keynes sont décelées. II s'avère que Soros est circonspect plutǒt que nihiliste quant aux possibilityés de la connaissance économique. Des développements dans l'analyse économique compatibles avec l'optique de Soros sont discutés.

Notes: This paper presents the first attempts by economists to estimate an equation of the demand curve for sexual relationship partner attributes. The focus is on the age of partner sought as the item demanded. A sample of newspaper ‘personal ads' is used to construct the demand curve. The estimates show clear evidence of age trade offs in partner search which vary by gender. There is evidence that financially constrained men will trade down in terms of market desirability, i.e., up in partner age, but also that women will offer to buy younger partners with financial signalling.〈section xml:id="abs1-2"〉〈title type="main"〉ZUSAMMENFASSUNGDieser Artikel präsentiert die ersten Versuche von Ökonomen, eine Gleichung für die Nachfragekurve nach Eigenschaften von Partnern bei der Partnersuche zu schätzen. Das Hauptinteresse liegt dabei auf dem Alter des Partners. Eine Stichprobe aus Kontaktanzeigen in Tageszeitungen dient dazu, die Nachfragekurve zu konstruieren. Die Schätzungen zeigen deutlich, dass Altersunterschiede bei der Partnersuche kompensiert werden müssen. So wurden Beweise dafür gefunden, dass Männer mit beschränkter finanzieller Ausstattung vom Markt weniger nachgefragt werden, also nur altere Partner finden, und Frauen versuchen, jüngere Partner durch finanzielle Anreize zu kaufen.〈section xml:id="abs1-3"〉〈title type="main"〉RÉSUMÉCet article nous présente les premières tentatives faites par les économistes afin d'évaluer la courbe de dernande portant sur les caractéristiques du partenaire sexuel. L'accent est mis sur l'ǎge du partenaire recherché comme étant le critère essentiel. C'est grǎce à un échantillon de ‘petites annonces' parues dans les journaux que la courbe a été tracée. Ainsi les hommes ayant des contraintes financières se montreront plus conciliants quant à l'ǎge. En d'autres termes, ils accepteront des partenaires plus ǎgées tandis que les femmes jouissant des moyens financiers se proposeront d'acheter des partenaires plus jeunes.

Notes: Abstract— Sphere-reinforced metal-matrix composites are modelled as a three dimensional array of hexagonal cylinders, each one with a broken or intact spherical reinforcement at its centre. Using this model, the stress-strain response of the composite in uniaxial tension was obtained. A parametrical analysis of the influence of matrix and reinforcement properties as well as volume fraction on the ductility of these composites was performed. It was found that the decrease in ductility with respect to the unreinforced matrix depended mainly on the reinforcement/matrix strength ratio and on the defect distribution in the particulates.

Notes: Abstract— Since the degradation effect due to environment on the cracking of materials depends on time, the loading rate has an important influence on the parameters that characterise its behaviour. This work analyses the effect of loading rate on the resistance to hydrogen induced cracking (HIC) of two microailoyed steels, E690 and E500. Monotonic loading tests were performed on precracked CT samples using a slow strain rate machine. Tests were done under constant displacement rate varying from 4.1 × 10–7 m/s to 8.2 × 10–10m/s on the two steels that were cathodically charged with hydrogen at different current densities (1, 5 and 10 mA/cm2) to obtain different hydrogen concentration levels inside the material.Based on an analytical study, the initiation conditions for cracking as well as the crack propagation rates were determined in each case, and analysed as a function of K1. An extensive fractographic SEM study has been performed to help in the analysis of the different zones of behaviour obtained as an effect of loading rate, for each material and environmental condition used.

Notes: Abstract— A reaction sintering route is developed to produce, “in situ”, composites of alumina-aluminium titanate using alumina and titania as starting powders. Aluminium titanate, can be formed by a solid state reaction between Al2O3 and TiO2 at temperatures above the eutectoid temperature of 1280°C. These composites have different grain sizes of alumina matrix and a different quantity and distribution of aluminium titanate according to the heating cycle used.In the present work direct push-pull tests under cyclic loads have been carried out with both monolithic alumina and alumina-aluminium titanate composites. It has been found that all the samples show a decrease in tensile strength with the number of applied cycles of loading when plotted in graphical form but the slopes of these graphs for both Al2O3-Al2TiO5 composites are lower than for the alumina specimens. The role of aluminium titanate and the alumina matrix grain size in fatigue crack growth resistance has been studied during push-pull tests, where failure occurs by catastrophic propagation of small surface cracks after a very short regime of subcritical crack growth. These results have been compared with measurements of slow stable fatigue crack growth rates in Al2O3-Al2TiO5 composites carried out elsewhere with pre-notched specimens of the compact tension type. These latter tests provide information about the behaviour of significantly long cracks, i.e. cracks that are several millimetres long.

Notes: Abstract— The Technical Committee “Ceramics” (TC 6) of the European Structural Integrity Society (ESIS) organized a round robin relating to the fracture toughness of ceramic materials at room temperature. Five materials were tested with five testing methods by eighteen laboratories. The five testing methods were: chevron notched beam in four point bending, direct measurement of the cracks emanating from a Vickers indentation, indentation strength by four-point bending, single edge precracked beam in four-point bending, and single edge notched beam in four-point bending. The results of the round robin performed in the period 1993 to 1994 are presented and discussed.

Notes: Abstract— This paper reviews the stress intensity factor, limit load, compliance and J-integral functions for a centre cracked tensile (CCT) specimen available in the literature. Compliance and J-integral functions are derived from the optimum stress intensity factor and limit load solutions. The functions are compared with the results obtained from two-dimensional finite element analyses of the specimen.The finite element results have confirmed the accuracy of the compliance and limit load functions available in the literature and suggest that the unloading compliance technique, based on crack mouth opening displacement, could be developed for a CCT specimen. Non-linear finite element analyses have shown that J can be estimated from the measured load versus load-point displacement behaviour providing a/W≥ 0.5

Notes: Abstract— The behaviour of fatigue cracks in an Al-alloy under cyclic compression, either with or without overloads, was studied. For constant-amplitude compressive cycling, a non-catastrophic (saturation) character of the fatigue crack behaviour was confirmed, with the final depth of a crack depending on the applied load level. Single (tensile or compressive) intermittent overloads were shown to re-activate a previously arrested crack while reversed (tensile—compressive or compressive—tensile) ones were also shown to maintain continual fatigue crack extension under otherwise fully compressive cycling.

Notes: Abstract— A new method for accelerating the collection of near-threshold corrosion fatigue crack propagation data, using local hydrogen embrittlement in the crack tip region, has been investigated for ASTM A710 HSLA steel. Fatigue tests were conducted at 10 and 0.2 Hz (stress ratio, R= 0.1) on “constant K” contoured double cantilever beam (CDCB) specimens, to establish near-threshold crack growth rates in a locally hydrogen charged region at the crack tip. Hydrogen charging was then discontinued and crack growth rates were monitored in the uncharged material. Near-threshold fatigue crack growth rates were found to be 100 times faster in the locally hydrogen charged specimens than in the uncharged material. Fatigue thresholds, ΔKth, were defined in less than one fifth the time required for load shedding tests in air at 0.2 Hz. Although demonstrated for HSLA steels, the technique is applicable to any material which can be embrittled by hydrogen.

Notes: Abstract— The objective of this work is to study the delamination growth behaviour of hybrid composite-aluminium bonded laminates. A modified Double Crack Lap Shear (DCLS) specimen was chosen for this study. An expression relating the delamination size and the compliance of a DCLS specimen was derived, and a test method for the delamination growth rate in DCLS specimens developed. The delamination sizes and the delamination growth rates of DCLS specimens were determined by monitoring the compliances of specimens during fatigue. Delamination growth rates at different stress ratios (R= 0.1, 0.3,0.5) were measured. A Walker-type equation for the delamination growth rate was obtained by a multiple linear regression analysis.It was shown that the compliance method for determining the delamination growth rate of DCLS specimens is not only convenient and practical, but also accurate. The delamination size in DCLS specimens increases linearly with cycles during fatigue, i.e. delamination growth rate is constant, independent of delamination size. The energy release rate was adopted to characterize delamination growth behaviour. Good agreement between the Walker equation and test results of the delamination growth rate was found.

Notes: Abstract— The aim of the paper is to compute the local crack face displacements of a linear elastic body containing an arbitrarily shaped plane crack. From the crack face displacements the local stress intensity factors can be derived.The boundary value problem for a plane crack of arbitrary shape, embedded in a linear elastic medium, has been treated by several authors by the singular integral equation (SIE) approach. Their computations lead to a set of hyper-singular integral equations for the Cartesian components of the unknown crack face displacements. To solve these equations the authors present a discretization procedure based on six-node triangular finite elements. A total set of 24 finite-part integrals defined over a triangular area can be developed. These 2D-finite-part integrals can be split into both a 1D-regular and a 1D-finite-part-integral by means of the polar coordinates so that they can be solved in closed form. Finally, the investigation of the SIEs is reduced to a discrete set of linear algebraic equations for the unknown nodal point values. The necessary steps will be demonstrated in detail. The derived closed-form solutions will be offered in the text and in the appendices.

Notes: Abstract— A new tool is presented to investigate cleavage fracture surfaces. It is based on the combined techniques of crystal orientation measurements using the Electron Back-Scatter Diffraction (EBSD)-technique and 3-dimensional surfaces reconstruction by an Automatic Surface Reconstruction System (ASRS).With this tool we can perform crystallographic fractometry of cleavage fracture facets of polycrystals within the limits of the resolution of a Scanning Electron Microscope (SEM), e.g. we can determine the crystallographic indices of cleavage planes and of directions on such planes.

Notes: Abstract— Ordinary ceramic refractories are used as lining material for industrial pyro-processes. A high resistance to mechanical failure from an imposed strain or thermal shock is usually termed “flexibility”. A scientific approach to enhance this property is hindered by the fact that there is a lack of understanding, definition and measurement of this parameter in relation to its physical basis.Wedge splitting tests were performed on a variety of typically shaped refractories together with standard procedures. This type of test enables stable crack propagation even for relatively large specimen dimensions that are necessary due to the size effect. High “flexibility” proved to be achievable in low brittleness materials and can be characterised by a brittleness number, the characteristic length or the thermal shock fracture resistance parameter according to Hasselman. A sufficient decrease of brittleness can be successfully achieved by the formation of precracks during the burning process which enhance the development of a fracture process zone. For a magnesia refractory (with additions of magnesia-alumina spinel) a friction bridging mechanism plays an important role in reducing brittleness.

Notes: Abstract— This paper describes the microstructure of Type 304 stainless steel after cyclic loading at room temperature under tension-torsion non-proportional strain paths. The degree of cyclic non-proportional hardening is correlated with changes in the dislocation substructure. Dislocation cells, dislocation bundles, twins and stacking faults are all observed. The type of microstructure formed and resultant stress response is dependent on the degree of non-proportional loading and strain range. Cyclic stress range was uniquely correlated with mean cell size.

Notes: Abstract— Multiple underloads and overloads with constant ΔK were carried out on centre-cracked tension specimens. It was found that when shear lips develop, underloads or overloads affect the crack growth rate da/dN and the subsequent retardation. The appearance of the shear lip fracture surfaces depends on the frequency. At higher frequencies a greater number of rough shear lip fracture surfaces will develop, while at lower frequencies there is a tendency towards smooth shear lips. The amount of crack closure differs in each case. It was found that the type of shear lip, rough or smooth, can be related to the effect on da/dN during and after underloads. The effect of rough and smooth shear lip growth was investigated in constant ΔK tests, performing these tests with and without crack closure.

Notes: Abstract— In this paper, a stress and modal analysis of an ultrasonic vibration system consisting of a notched specimen and one or two amplifying horns have been performed by using 3D finite element calculations. The stress intensity factors in ultrasonic fatigue crack propagation are evaluated by means of displacement and energy approaches. The particular advantages as well as limitations of the two approaches are briefly discussed. Two types of ultrasonic fatigue loading, with a different stress ratio, are exerted on the specimen. From a comparison of the results a conclusion is formed that the energy approach is more accurate; it also has a wide range of practicality in engineering industries.

Notes: Abstract— In this study, the relation between fracture toughness and mechanical properties, grain structure, temperature and strain rate is analysed on the basis of a thermo-activation analysis of the plastic deformation of metals.As a result of the study, the relationships obtained are of sufficient accuracy in relation to standard cracked samples of many steels.These relations can be used as a tool when designing new alloys which have a strong resistance to crack growth.This study is limited to temperatures in the range 0 ≤ T ≤ 0.2Tm and BCC metals.

Notes: Abstract— A numerical model for determining the pitting resistance of gear teeth flanks is presented in this paper. The model considers the material fatigue process leading to pitting, i.e. the conditions required for crack initiation and then simulation of fatigue crack propagation. The theory of dislocation motion on persistent slip bands is used to describe the process of crack initiation, where the microstructure of a material plays a crucial role. The simulation of crack growth takes into account both short crack growth, where the modified Bilby, Cottrell and Swinden model is used for simulation of dislocation motion, and long crack growth, where the theory of linear elastic fracture mechanics is applied. The stress field in the contact area of meshing spur gear teeth and the functional relationship between the stress intensity factor and crack length are determined by the finite element method. For numerical simulations of crack initiation and crack propagation in the contact area of spur gear teeth, an equivalent model of two cylinders is used. On the basis of numerical results, and with consideration of some particular material parameters, the service life of gear teeth flanks is estimated. The developed model is applied to a real spur gear pair, which is also experimentally tested. The comparison of numerical and experimental results shows good agreement and it can be concluded that the developed model is appropriate for determining the pitting resistance of gear teeth flanks.

Notes: Abstract— Stress intensity factors for quarter-elliptical corner cracks emanating from a circular hole are determined using a 3-D weight function method combined with a 3-D finite element method. The 3-D finite element method is used to analyze uncracked configurations and provide stress distributions in the region where a crack is likely to occur. Using this stress distribution as input, the 3-D weight function method is used to determine stress intensity factors. Three different loading conditions, i.e. remote tension, remote bending and wedge loading, are considered for a wide range of geometrical parameters. The significance of using 3-D uncracked stress distributions is studied. Comparisons are made with solutions available in the literature.

Notes: Abstract— This paper presents the results of an experimental testing programme to examine the uniaxial creep, low cycle fatigue and creep/fatigue interaction behaviour of a Ni-base superalloy at 700°C. The material is used in the manufacture of aeroengine turbine discs. A creep continuum damage mechanics model is shown to be capable of accurately predicting the creep and creep rupture behaviour of the material. A healing term has been incorporated into the damage mechanics model to allow the behaviour under creep/fatigue conditions to be described.

Notes: Abstract— The effect of short periods of mixed-mode overloading on the environmental hydrogen induced fracture life of 0.42%C, 0.87%Cr, 0.21%Mo steel has been studied. Tests were performed in 0.5 mol/L H2SO4 solution under continuous hydrogen charging conditions using a weight loading system. Experimental results show that the application of mixed-mode overloads can cause more severe crack growth retardation than those of mode I. Possible mechanisms responsible for the retardation of subsequent crack growth, such as crack deflection, plasticity-induced residual compression stresses, dislocation shielding and overload damage, are examined.

Notes: Abstract— The whole damage process in a finite sized specimen with interacting microcracks is simulated by a method combining the closed form crack solutions with boundary elements. Interactions among microcracks and boundary elements are taken into account with an explicit interaction matrix. A coalescence criterion is assumed to rule the intersection behaviour and propagation arrest. The fatal coalescence cluster resulting in the failure of the specimen, out of many intersections of propagating microcracks, is identified with a particular coalescence matrix. The numerical model proposed in this paper can be used to simulate the damage process in a brittle specimen of any shape, under arbitrary plane stress conditions.

Notes: Abstract— Creep Crack Growth (CCG) tests were performed at 405°C on specimens cut out of the cold bent extrados of five tubes of a C-Mn-Mo steel. Intergranular fracture and grain boundary cavitation was less in the C-Mn-Mo than in the C-Mn steels, in accordance with better CCG resistance of the former material. The dimensions and hardness variation across the crack tip process zone were measured by microhardness profiles performed on metallographic sections of the broken samples. TEM analysis of the dislocation patterns close to the fracture surface confirmed the presence of temperature- and stress-induced plasticity phenomena. A significant enrichment of N at grain boundaries (GB) inside the process zone was detected by Auger spectroscopy; N not only inhibits dislocation motion and stress field relaxation at the crack tip but also causes a decrease in GB cohesion ahead of the crack tip. These results help in understanding the micromechanisms which reduce the creep ductility of C-Mn-Mo and C-Mn cold bent tubes and the role of chemical composition in improving CCG resistance.

Notes: Abstract— The effect of specimen size on fracture toughness of a pipe-grade high density polyethylene has been examined using the J integral approach. It was found that the size requirements set up by common standards appear inadequate for this material. Measurements at low temperatures, at which a plane strain fracture toughness value could be obtained, turned out to be very effective in establishing a more appropriate size requirement for this material.

Notes: Abstract— Fractographic peculiarities of fatigue crack development are studied in cruciform specimens of D16T aluminium alloy under out-of-phase biaxial tension and tension-compression. In the range of the biaxial load ratios λ from −0.5 to +0.5 and an R-ratio of 0.3, fatigue striation formation took place beyond a crack growth rate near to 4 × 10−8 m/cycle. The striation spacing and the crack growth rate increase as the φ-angle of the out-of-phase biaxial loads increases in the range of φ-angles from 0° to 180°. The ratio between the increment of crack growth, da/dN, and the striation spacing, δ, is approximately 1 to 1 when da/dN is greater than 4 × 10−8 m/cycle. The relationship between the number of cycles from the beginning of a test up to the growth rate of 10−6 m/cycle (Nd), and the crack growth period, NP, from when the crack initiates up to the instant when that growth rate is reached, was determined for different λ ratios and φ angles. The value of Nd decreases as the φ angle is increased in the range from 0° to 1807deg;.Cycle loading parameters must be taken into account in order to describe the crack growth period when using a unified method that involves an equivalent stress intensity factor Ke=KIF1(λ, R)F2(φ). The values of F2(φ) were determined.The calculated fatigue crack growth period, Nc, applicable up to and including the stage of fatigue striation formation (predicted by using both of the F1(λ, R) and F2(φ) functions) is correlated with the experimental data and the error is of the order of 15%.

Notes: Abstract— The occurrence of brittle stable crack growth before unstable fracture was demonstrated with the aid of heat-tinting, for a ferritic matrix super duplex stainless steel which had been age-hardened at 475°C. The critical crack tip opening displacement for stable crack growth, i.e. the crack initiation toughness, was measured using the direct-current-potential drop crack monitoring technique. A quantitative model for the effect of temperature and age-hardening on the brittle crack initiation toughness is described.

Notes: Abstract— Fatigue crack propagation characteristics are measured by continuously determining the resonant frequency in vibrating systems, which is stabilized through a feedback control loop. The precisely controlled resonant frequency is related to the crack length by a nonlinear model based on fracture mechanics, hence crack growth can be monitored with respect to time with very high accuracy. The nonlinearity due to the opening and closing of the crack needs to be taken into account. In contrast to conventional fatigue tests, which require a long duration of time due to the high numbers of load cycles at low frequencies, the proposed technique operates at much higher frequencies, i.e. in the range of 100 Hz to 100 kHz. Thus the required time for measurements in the high cycle fatigue range is considerably reduced. The experimental setup is simple and inexpensive and does not require high energy inputs.