68,342 research outputs found
Tangent cones of monomial curves obtained by numerical duplication
No full textGiven a numerical semigroup ring , an ideal of and an odd element , the numerical duplication is a numerical semigroup, whose associated ring shares many properties with the Nagata's idealization and the amalgamated duplication of along the monomial ideal . In this paper we study the associated graded ring of the numerical duplication characterizing when it is Cohen-Macaulay, Gorenstein or complete intersection. We also study when it is a homogeneous numerical semigroup, a property that is related to the fact that a ring has the same Betti numbers of its associated graded ring. On the way we also characterize when is Cohen-Macaulay and when is a canonical module of in terms of numerical semigroup's properties, where is a canonical module of
Can society nurture humanistic marketing?
No full textFor more than four decades, academic debates on the morality of marketing have focused mainly on the advantages and disadvantages of marketing as an institution. This essay questions the usefulness of such debates to addressing many challenges of life in contemporary society and argues that engagement in such discussions will only entrap us in vicious circles of argumentation. The author calls for collective social responsibility and argues that humanistic marketing can only be realised in a humanistic society
Self-centering walls strengthening by high-performance concrete: a feasibility study
Get PDFIn this research, the feasibility of strengthening self-centering walls by high-performance concrete was investigated through an experimentally validated finite element model. The effects of the wall’s axial stress and tendons’ prestressing ratios on the wall’s damage, and the effectiveness of potential strengthening approaches were studied through 40 independent scenarios, and 360 different cases. Using the estimated damage from numerical results at the compression zone near the bottom corners, the maximum compressive strain of the concrete at the walls’ toe regions was estimated. Using the calibrated concrete strain, a practical approach was proposed to delimit both the walls’ damaged height and the crushed height. The heights’ information was used to investigate two potential strengthening approaches by either retrofitting (for damaged walls) or rehabilitating (for newly constructed walls). Increasing the axial stress ratio decreased the maximum developed compressive strain in the toe region, whereas the tendons’ prestressing ratio did not show significant effects. Moreover, by increasing substantially the axial stress ratio, the damaged region increased, whereas by increasing the tendons’ prestressing ratio the opposite effect was produced. Based on the findings of this research, it was concluded that for walls with lower axial stress ratio (< 0.095), both the proposed strengthening approaches resulted in similar outcomes, while for walls with higher axial stress ratio, casting the bottom portion with HPFRC led to sounder/safer designs
Analysis of the mechanical response of a woven polymeric fabric with locally induced damage
No full textAn experimental study and theoretical evaluation on the effect of specimen geometry and loading configuration on recorded fracture toughness of brittle construction materials
No full textGeometry and loading condition of cracked specimens may affect the fracture toughness results and hence the evaluation of differences in measured fracture toughness values is necessary for many construction materials. In the absence of standard methods for measuring the general mode fracture resistance of asphaltic concrete materials, in this study the fracture toughness values for such materials were measured and compared by means of three different test specimens and methods. All three fundamental fracture modes (i.e. pure I, pure II, and pure III) and related mixed-mode loading cases (i.e. I/II and I/III) were evaluated. The test specimens were edge-notched disc bend (ENDB), edge-notched diametrically compressed disc (ENDC), and semi-circular bend (SCB). During the experimental program the specimens made of asphaltic concrete were tested at two temperatures of −5 and −25 °C and analyzed using the linear elastic fracture mechanics (LEFM) principles. Also, several theoretical frameworks were compared and examined to evaluate their applicability and accuracies for predicting the trends of experimentally obtained test data. The results showed that the geometry and loading configuration can significantly affect the measured fracture toughness values under pure mode II and pure mode III. The value of mode I fracture toughness measured by three specimens was almost the same (with small differences of 4%) and equal to 0.68 MPa√m. At pure mode II, the fracture toughness evaluated by the ENDB specimen was about 20% higher than that of the SCB specimen (with averages of 0.83 and 0.68 MPa√m for the ENDB and SCB samples, respectively). For pure mode III case, the measured fracture toughness by the ENDC specimen was approximately 60% higher than that of the ENDB specimen (with averages KIIIc = 0.62 MPa√m for the ENDC and 0.42 MPa√m for the ENDB specimen). Among the investigated mixed mode fracture criteria, the GMTS criterion provided accurate predictions for KIIc/KIc ratios. Also, 3D-MTSN, and 3D-MTSED criteria were more precise than others for mode I/III predictions. The evaluations indicated that the discrepancy between the measurements is mainly due to sign and magnitude of T-stress parameter
Use of EO-1 Hyperion hyperspectral imagery for discriminating arid vegetation
No full textReza Jafari, Megan Lewis and Bertram Ostendor
Comparison of mixed mode I/III fracture toughness data obtained from the ENDB specimens manufactured by gyratory cylinders with two diameters of 100 and 150 mm
No full textDifferent specimens have been developed to characterise the fracture parameters. Recently, a disc shape specimen entitled ‘edge notched disc bend’ (ENDB) sample was introduced; it is used for conducting pure mode I, III, and related fracture mode mixities. In this paper, to extend the application of ENDB specimen, a large number of mode I, III, and I/III fracture toughness experiments were conducted on HMA at three different low-temperatures (−5, −15, and −25°C) and by applying two rates of loading (1 and 5 mm/min). The effect of ENDB radius (i.e. 50 and 75 mm) for a constant thickness of 30 mm was investigated experimentally. Based on the data, both ENDB diameters result in nearly the same mixed I/III fracture toughness values,. The difference between the fracture toughness of both ENDB sizes was less than 8%. Hence smaller size of ENDB sample with a diameter of 100 mm can be employed successfully instead of 150 mm (that is commonly used in many asphalt fracture toughness studies). The results also indicated that the fracture toughness values in the full ranges of mode I/III case increase as the test temperature decreases (about −7% and −15% by increase from −25 to −15°C and −5°C)
Thermal expansion anomalies of R(Fe, M)(12) (R=Y, Nd; M=Mo and Si)
No full textStructural and thermal-expansion anomaly studies on R(Fe,M)(12) (R=Nd and and Y, M=Mo and Si) compounds were performed by x-ray diffraction. Mo atoms occupy the 8i site. While Si atoms occupy the 8f and 8j sites but not the 8i site. Thermal-expansion anomaly shows only in ab plane in the Mo compounds, while becomes very weak and along with only the c axis in the Si compounds. The anomaly was attributed to the contribution of the interactions of short Fe-Fe distances similar to the previous explanation on other R-Fe intermetallics and that of other strongly positive interactions such as 8j-8j. (c) 2005 American Institute of Physics.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000230168300025&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, AppliedSCI(E)EICPCI-S(ISTP)
Repair efficiency evaluation for cracked asphalt mixture pavement in different ambient temperatures using bitumen and polymer concrete as repair materials
No full textThis paper studies the effect of crack repairing process on the behavior of pavement at four ambient low and medium temperatures ranging from −20 °C to 30 °C. Asphalt mixture samples in the shape of semi-circular bend (SCB) were tested in intact, cracked, and repaired conditions under tensile or opening mode of loading. Two adhesive types: namely pure bitumen and polymer concrete were used to repair the crack. To investigate the efficiency of the repair process, some indexes such as failure load, initial and post-failure energies, and failure patterns were evaluated using the intact and cracked SCB specimens. Failure patterns showed that in the repaired specimens with pure bitumen, the failure initiates from the mid-section (i.e., from the repaired zone), while in polymer concrete repaired specimens, the failure initiates far from the repaired zone. Experimental results also revealed that the temperature has a noticeable effect on the repair efficiency using bitumen adhesive. Indeed, for sub-zero temperature conditions, such repairing material partially provided acceptable integrity for the pavement compared to the intact asphalt mixture. But, for service temperatures greater than + 10 °C, repair with bitumen was inefficient. However, repair with polymer concrete was efficient in all temperatures, and the strength of specimens repaired by the polymer concrete was even higher than the intact specimen. Similar trends and results were also obtained for the work of failure indexes
Chemical Characterization of the Essential Oil Compositions from Iranian Populations of Hypericum perforatum L.
No full textHypericum perforatum L. (St. Johns’ wort) is the most commercially important species of the genusHypericum and contains a wide range of components including naphthodianthrones, phloroglucinols,tannins, xanthones, phenolic acids and essential oil. In the present study, for the first time the varia-tion of the essential oil compositions among 10 wild populations of H. perforatum growing in Iran wasassessed. According to the GC-FID and GC–MS analyses, a total of forty-six components were identifiedin 10 H. perforatum populations with relatively high variation in their composition. Among chemicals,2,6-dimethyl-heptane (6.25–36.07%), ̨-pinene (5.56–26.03%), ı-cadinene (0.0–22.58%) and -cadinene(0.0–16.9%) were found as the most abundant compounds in their essential oils. The higher amounts ofthis components were identified in the oil of Azadshahr, Kharw, Nor and Mashhad populations, respec-tively. Cluster analysis grouped the studied populations into four different chemotypes: chemotype I(ı-cadinene/ ̨-humulene), chemotype II ( ̨-pinene), chemotype III (-cadinene) and chemotype IV (2,6-dimethyl-heptane/ ̨-pinene). In fact, local abiotic factors such as moisture, temperature, topography,edaphic and/or biotic selective factors (associated fauna and flora) act on loci of the terpene-biosynthesispathways and contribute to the emergence of different chemical oil profiles. Intraspecific variation in thechemical profile of the Iranian populations provided possibility of selection of those with specific aromasor chemical profiles accompanied with biological document, being of interest at industrial level. Obtainedresults provided new insight for Iranian H. perforatum germplasm to be used in breeding programs anddevelopment of effective conservation strategies
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