Theoretical and experimental researches of post-micro-buckling for fiber-reinforced composites

Post-microbuckling is a fundamental feature of compressive failure process for the unidirectional-fiber-reinforced composites and laminated composites. The post-microbuckling behavior of composites under compression in the light of the Kevlar49-reinforced 648/BF3.400 (brittle epoxy) and EP (flexible epoxy) is studied, theoretically and experimentally. Analytical results of compressive strength are in good agreement with experimental results, qualitatively and quantitatively. By the experimental research, the post-microbuckling feature of the advancing kink band model is clearly displayed.

On post-instability processes in adiabatic shear in hot rolled steel

EXPERIMENTS carried out using a split Hopkinson torsional bar have shown that only one shear band develops in specimens of hot rolled steel which break during testing. We observed, however, that in specimens which were not deformed to failure, several fine shear bands appeared. We believe that these formed during the loading cycle before the appearance of the final shear band and were not due to the effect of unloading. So we developed a numerical model to study the evolution of shear banding from several finite amplitude disturbances (FADs) in both temperature and strain rate. This numerical model reveals the detailed processes by which the FADs evolve into a fully developed shear band and suggests that beyond instability, the so-called shear banding process consists of two stages: inhomogeneous shearing and true shear-banding. The latter is characterized by the collapse of the stress and an abrupt increase of the local shear strain rate.

Linguistic Polarization and Conflict in the Basque Country

This paper investigates the relationship between linguistic polarization and conflict in the Basque Country. During the 40 years of Franco’s dictatorship the use of the Basque language was banned. Therefore, there may be some linguistic roots underlying the conflict in the Basque Country. We show that at the municipality level, linguistic polarization reduces the level of conflict. This finding is robust to various ways of measuring linguistic and ideological polarization and the inclusion of other covariates. In addition, we find that a high level of the stock of human capital is beneficial for reducing conflict intensity.

Methods for Measuring Aggregate Costs of Conflict

This paper reviews the methods for measuring the economic cost of conflict. Estimating the economic costs of conflict requires a counterfactual calculation, which makes this a very difficult task. Social researchers have resorted to different estimation methods depending on the particular effect in question. The method used in each case depends on the units being analyzed (firms, sectors, regions or countries), the outcome variable under study (aggregate output, market valuation of firms, market shares, etc.) and data availability (a single cross-section, time series or panel data). This paper reviews existing methods used in the literature to assess the economic impact of conflict: cost accounting, cross-section methods, time series methods, panel data methods, gravity models, event studies, natural experiments and comparative case studies. The paper ends with a discussion of cost estimates and directions for further research.

Profit and Cost in "Modern" Post-Marxian Profit Theory: A Case Study from Varian's "Intermediate Microeconomics"

In this paper, I examine the treatment of competitive profit of professor Varian in his textbook on Microeconomics, as a representative of the “modern” post-Marxian view on competitive profit. I show how, on the one hand, Varian defines profit as the surplus of revenues over cost and, thus, as a part of the value of commodities that is not any cost. On the other hand, however, Varian defines profit as a cost, namely, as the opportunity cost of capital, so that, in competitive conditions, the profit or income of capital is determined by the opportunity cost of capital. I argue that this second definition contradicts the first and that it is based on an incoherent conception of opportunity cost.

The Comovement between Monetary and Fiscal Policy Instruments during the Post-War Period in the U.S.

This paper empirically studies the dynamic relationship between monetary and fiscal policies by analyzing the comovements between the Fed funds rate and the primary deficit/output ratio. Simple economic thinking establishes that a negative correlation between Fed rate and deficit arises whenever the two policy authorities share a common stabilization objective. However, when budget balancing concerns lead to a drastic deficit reduction the Fed may reduce the Fed rate in order to smooth the impact of fiscal policy, which results in a positive correlation between these two policy instruments. The empirical results show (i) a significant negative comovement between Fed rate and deficit and (ii) that deficit and output gap Granger-cause the Fed funds rate during the post-Volcker era, but the opposite is not true.

Markov Switching Risk Premium and the term structure of interest rates. Empirical evidence from US post-war interest rates

This paper considers the basic present value model of interest rates under rational expectations with two additional features. First, following McCallum (1994), the model assumes a policy reaction function where changes in the short-term interest rate are determined by the long-short spread. Second, the short-term interest rate and the risk premium processes are characterized by a Markov regime-switching model. Using US post-war interest rate data, this paper finds evidence that a two-regime switching model fits the data better than the basic model. The estimation results also show the presence of two alternative states displaying quite different features.