Search

The Hermans orientation factor is a scalar giving a simple assessment of molecular or crystal orientation in a polymer. It is usually determined from X‐ray diffraction measurements. The evaluation of the Hermans orientation factor is proposed from the diffraction analysis of only a single diffracting plane. The estimation relies on (a) the assumption that the polymer crystals possess a cylindrical symmetry with respect to the chain direction and (b) that the processing conditions induce a transverse isotropy of the polymer chains. A practical consequence of the proposed analysis is that the Hermans orientation factor can be computed from a single 1D diffractogram. This enables fast evaluations since even low signal‐to‐noise ratio signals can be processed with optimal noise reduction. An illustration of this method for uniaxially compacted polytetrafluoroethylene (PTFE) powder is presented. The crystalline orientation is followed during in situ crystallization experiments with a fine time resolution. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Economics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Economics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The influence of the cooling rate after melting on the crystalline weight fraction of pure poly(tetrafluoroethylene) (PTFE) was derived from differential scanning calorimetry tests. Specimens made of pure or filled PTFE were manufactured by isostatic or constrained uniaxial cold pressing, up to different values of the porosity. Dilatometry tests were carried out on these specimens while imposing various heating-cooling treatments. The deformations recorded during these tests strongly depend on the mode and level of compaction. The original procedures presented, herein, made it possible to identify that these macroscopic deformations, which are strongly anisotropic for uniaxially pressed specimens, result from the combination of different independent mechanisms. The mechanisms that were distinguished are reversible thermal expansion, void closure, crystalline to amorphous and vice versa transformations, and recovery, which were not observed for isostatically pressed specimens. It was also shown that, after being subjected to a standard sintering treatment, anisotropically pressed specimens still exhibit anisotropic crystallization strains. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Degradation in bauxite refractory linings used in steel plants is localized in the slag-impregnated zone of refractories. It is proposed to estimate the contribution of the pressure of the impregnated liquid on the degradation of refractories. The study of the gradient of chemical composition allows for the evaluation of the liquid content, the oxide content in the liquid phase, and the “slag” viscosity. The thermomechanical analysis of a porous refractory impregnated by slag enables us to propose analytical expressions for a rapid estimate of the maximum “slag pressure” and its location as well as the level of thermoelastic stresses. [ABSTRACT FROM AUTHOR]

Abstract This paper argues that new immigrants cluster in culturally homogeneous groups in the host country because of imperfect information. However, a pulling effect exists provided that the cultural communities are not too large. With a panel of migration flows to the major O.E.C.D. countries from the mid 1980s to the mid 1990s, it is shown that the existence of similar cultural communities attracts new immigrants. However, the effect is not homogeneous for all types of source and destination countries. Furthermore, the pulling effect is shown to fall to zero for cultural communities above a certain threshold size. [ABSTRACT FROM AUTHOR]

This article shows that governments have no incentive to introduce nontariff barriers (NTBs) when they are free to set tariffs but they do when tariffs are determined cooperatively. Quotas are preferred to antidumping restrictions so that the model is consistent with a progression from using tariffs only to quotas and then to antidumping constraints (when quotas are eliminated). There is a corresponding narrowing of the range of industries affected by trade restrictions. Simulating the model, the degree of tariff liberalization and of replacement of tariffs by NTBs are shown to depend on industry characteristics in line with stylized facts. [ABSTRACT FROM AUTHOR]

Examines the main economic effects of the so-called completion of the Internal Market in 1992 on European Community members. Intra-industry trade theory; Strategic trade policies; Obstacles that create local markets; Profit-maximizing decisions of firms induced by the physical, technical or fiscal presence of borders.

This paper investigates the effects of reciprocal tariff reductions in a two-identical country model of product differentiation. It makes three points. First, the existing results about market structure effects of trade liberalization can easily be replicated from a one-dimensional characteristic space model in which the prohibitive tariff rate is endogenously determined. Secondly, these effects depend crucially on the initial ad valorem tariff rate. Thirdly, reciprocal tariff reductions alone do not necessarily warrant welfare gains. [ABSTRACT FROM AUTHOR]

Asserts that the rationalization gains often predicted by static applied general equilibrium models with imperfect competition and scale economies are artificially boosted by an unrealistic treatment of fixed costs. Sunk costs as exit barriers; Sunk costs as entry barriers; European trade integration; Calibration of nonsunk component of costs.

Investigates the choice of product attribute in a model of horizontal differentiation with international trade. Use of the Hotelling approach; Product attributes and market of production; Association of product differentiation with market penetration and market sharing; Prediction of the model.