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Step-change in Enhancing Extrusion as a Unit Operation
YesExtrusion-a unit operation in polymer processing has been in extensive use since the great age of plastic technology. It is a simple operation that enables within one equipment the sequential conveying of solid polymer chips or powder, their melting, mixing, pumping and shaping via a die into a variety of high tonnage and/or value products. Pipes, bottles, films are the most common examples but the list of applications is endless from tiny micromoulded parts to large structural profiles. Extrusion is not limited to plastics but is used hot or cold to process soft solids like food, industrial and pharmaceutical pastes, as well as metals and ceramics. Most of the advances in extrusion processing have concentrated in improving the essential functions of extrusion: solid conveying, melting, pumping and mixing. The literature abounds with descriptions of such advances pushing the limits of the extrusion in an incremental way. In this paper, we describe step-changes in enhancing extrusion, which opens up new applications to better old technology-make them safer, cheaper and cleaner. The new designs presented in this paper have also the potential to develop new reactor technology for viscous fluids
Product differentiation and intra-industrial trade: Quantitative assessment in the case of Tunisia
In this article we try to analyze the extend of product differentiation in the Tunisianâs context, by relying on an investigation drived at a sufficiently disaggregated level of sectors. In the first section, we tend to expose the relationship between market structure, product differentiation and intra-industrial trade. Then, we reexamine in the second section some operational proxies of products variety that were previously analyzed by the empirical literature. In the third section, we tend to appreciate the strength of products differentiation in the specific case of Tunisia and in 8 different sectors
Error bounds for small jumps of L\'evy processes
The pricing of options in exponential Levy models amounts to the computation
of expectations of functionals of Levy processes. In many situations,
Monte-Carlo methods are used. However, the simulation of a Levy process with
infinite Levy measure generally requires either to truncate small jumps or to
replace them by a Brownian motion with the same variance. We will derive bounds
for the errors generated by these two types of approximation.Comment: 21 p
Structural Transformation in Developed and Developing Countries
Differences in key features of the development process across rich and poor countries can provide clues to the sources of the large variation of cross-country income. Kuznets included structural transformation as one of six stylized facts of economic development, nding that developed countries all followed the same process. In this paper, I compare structural transformation processes in developed and developing countries. I nd that developing countries follow distinct structural transformation paths that deviate from that followed by developed countries. A puzzling nding is the presence of substantial sectoral changes during times of economic stagnation or decline. --Africa,Asia,Latin America,Structural Transformation,Economic Development,Structural Change
The Macroeconomic Social Accounting Matrix of Tunisia in 1996
This paper shows the characteristics of the macroeconomic Social Accounting Matrix (SAM) of Tunisia in 1996. It is established that the SAM is one of the data bases of the Computable General Equilibrium (CGE) Models. These last years, the researchers have intensified the use of the SAM within the framework of the modelling of CGE within their work. The SAM is regarded as the general data base because it contains the whole relationship between the economic agents of a given economy, including the existing relationship on the level of table input â output. The SAM can be presented in two forms: the aggregate form (or macroeconomic) and desegregated form (or microeconomic). In this paper, we will focus on the first form of SAM corresponding to Tunisia during 1996. This study is made up of two sections. In the first section, we will present the construction of the unbalanced Macroeconomic Social Accounting Matrix (SAMmac) of Tunisia in 1996. This section includes three sub-sections. The first sub-section contains the accounts of our SAMmac in 1996. Then, the second sub-section will be devoted to the statistical sources used for the construction of our SAMmac. Finally, the last sub-section will concentrate on our SAMmac which is in imbalance because of the various sources used. We present, in the second section, the balancing of SAMmac of Tunisia in 1996 in basing upon the method known as ' Cross-Entropy '. Initially, in a first sub-section, we will define the ' Cross-Entropy ' approach. Then, in a second sub- section, we will use this last approach to balance our SAMmac. Conclusions follow.Social Accounting Matrix, Cross-Entropy, Tunisia, balanced of the SAM
Impacts of the Euro-Tunisian agreements of free exchange: evaluation by a Computable General Equilibrium Model in 1996
Until nowadays, the South-Mediterranean countries have focused on their strategic choice which consists in the creation of a Euro-Mediterranean Free Trade Area (FTA). Among the first participants in the constitution of this zone, is Tunisia, which signed an agreement of association with the European Union (EU). Since the signature of this agreement, Tunisia has been interested in improving its internal economic situation through internal reforms to facilitate the application of external reforms. With the coming into force of this agreement, the free euro-Tunisian exchange concerns exclusively industrial products, while the other products (farm produce) are going to be examined in the coming days. The object of this communication is to compare the effects of the free total exchange and the effects of the free industrial exchange between Tunisia and the EU in the Tunisian economy. This problem was estimated by means of a Computable General Equilibrium Model (CGEM). This document is going to be divided in two blocks of simulations. The first concerns total commercial liberalisation, while the second block consists in a partial commercial liberalisation. We notice that a progressive commercial liberalisation applied during a reasonable period remains an effective economic reform for a developing country. Moreover, such a liberalisation is considered as preferable when it is applied to one or to a certain category of product. In other words, free progressive industrial exchange between Tunisia and the EU is considered as a good strategy for the constitution of a Euro-Mediterranean FTA on the horizon 2010.CGEM, trade policy, Tunisia, trade negotiations, simulations
Various methods of balancing of the macro SAM of Tunisia during the year 2000
This paper has the aim of presenting the various methods of balancing applied to the macroeconomic Social Accounting Matrix (macro SAM) of Tunisia during the year 2000. These methods (method of entropy, method of least squares....) were used by the modellers of Computable General Equilibrium (CGE) whose would to balance the totals in columns and the totals in lines of the SAM of the developing countries in question. To be able to be regarded as the base of data of a CGE model, the matrix must check the principle of balance of the totals in columns and in lines of each one of these accounts.
Formation Response of High Frequency Electromagnetic Waves
Core samples from rock formations respond to electromagnetic radiation based on an effective permittivity, which depends on the conductivity and permittivity of the constituent components of the rock, as well as the geometric structure of these constituents and the frequency of the radiation. This study analyzes the effect, for radiation of 1 to 100 Mhz, of discrete inclusions having a different permittivity from the surrounding medium. The focus is on the effect of certain geometric features, namely, the individual size of the inclusions, their overall volume fraction, the presence of sharp edges, and their aspect ratio.
It is found that the volume fraction has the strongest impact on the effective permittivity, linear at first but higher order at higher volume fractions. The aspect ratio of the inclusions has a moderate effect, which is exaggerated in the extreme case of needle-like inclusions, and which can also be seen in a stronger nonlinearity. There is also a possibility that some features in the shape of the inclusion boundaries may influence the frequency dependence of the effective permittivity. Inclusion size and sharp edges have negligible effect
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