The role of transnational companies as oil suppliers to the United States

This paper analyzes the extent to which the international oil production of transnational companies meets the oil requirements of the United States. Disaggregated data from each company have been used to determine which companies (refineries) are importing crude oil, how much oil each transnational company is produced abroad, and where this production goes to. The analysis show that American international oil production represents a small part of U.S. oil imports. Two conclusions are reached. The first is that U.S. refineries buy the majority of the crude oil they process on the international market and, as a result, are dependent on the unstable conditions of this market. The second is that the economic interests the large American oil companies have abroad are far greater than those they have within the United States and, as a result, these companies do not play a decisive role in a national strategy to guarantee foreign supply.     

Implementing process views in the web service environment

Web service and business process technologies are widely adopted to facilitate business automation and collaboration. Given the complexity of business processes, it is a sought-after feature to show a business process with different views to cater for the diverse interests, authority levels, etc., of different users. Aiming to implement such flexible process views in the Web service environment, this paper presents a novel framework named FlexView to support view abstraction and concretisation of WS-BPEL processes. In the FlexView framework, a rigorous view model is proposed to specify the dependency and correlation between structural components of process views with emphasis on the characteristics of WS-BPEL, and a set of rules are defined to guarantee the structural consistency between process views during transformations. A set of algorithms are developed to shift the abstraction and concretisation operations to the operational level. A prototype is also implemented for the proof-of-concept purpose.     

Physical and mechanical properties of unsaturated polyester resin matrix from recycled PET (based PG) with corn straw fiber

In this study, composites of unsaturated polyester resin (UPR), synthesized from recycled polyethylene terephthalate (PET), with 10 to 40% in volume of corn straw fiber (CSF), were elaborated and studied the effect of fiber content on their physical and mechanical properties. The content of cellulose (48.97%), hemicellulose (24.06%), and lignin (6.59%) were determined by chemical characterization of CSF. The characteristic bonds of the UPR were identified as a cross-linking network between the styrene monomer (ST) and the unsaturated polyester (UP) through FTIR. Two decomposition stages were observed by TGA–DTG. The results of physical and mechanical properties showed that as the fiber content increased in the UPR, the water absorption increased (0.6% to 2.56%), on the other hand, the density (1218.23 to 1150.28 kg/m³), flexural strength (50.58 to 26.98 MPa), flexural modulus (2.66 to 2.29 GPa), tensile strength (8.62 to 3.65 MPa), tensile modulus (1.18 to 0.43 GPa), and hardness (81.67 to 65.67 Shore D), they decreased. SEM analysis showed some defects in the fiber distribution in the UPR, which affected the mechanical properties of the composites. This research contributes to the development of new material from use of two waste materials for the benefit of the environment.     

SLIDING MODES, Δ‐MODULATORS,AND GENERALIZED PROPORTIONAL INTEGRAL CONTROL OF LINEAR SYSTEMS

In this article, we attempt a reapproachment between sliding mode control of linear systems and classical control through the possibilities of evading state measurements and circumventing the use of asymptotic state observers in the sliding surface synthesis. This is shown to be possible thanks to the use of integral state reconstructors combined with iterated integral output error compensation. The proposed scheme is also robust with respect to unmatched perturbation inputs. A connection between sliding modes and classical analog Δ‐modulators, and their natural generalization, is also brought to attention as a tool for the realization of integral reconstructor based sliding mode control schemes.     

A Characterisation Schema for Software Testing Techniques

One of the major problems within the software testing area is how to get a suitable set of cases to test a software system. This set should assure maximum effectiveness with the least possible number of test cases. There are now numerous testing techniques available for generating test cases. However, many are never used, and just a few are used over and over again. Testers have little (if any) information about the available techniques, their usefulness and, generally, how suited they are to the project at hand upon, which to base their decision on which testing techniques to use. This paper presents the results of developing and evaluating an artefact (specifically, a characterisation schema) to assist with testing technique selection. When instantiated for a variety of techniques, the schema provides developers with a catalogue containing enough information for them to select the best suited techniques for a given project. This assures that the decisions they make are based on objective knowledge of the techniques rather than perceptions, suppositions and assumptions.     

Mechanical and Structural Properties of Expanded Extrudates Produced from Blends of Native Starches and Natural Fibers of Henequen and Coconut

The aim of this research was to evaluate the effects of barrel temperature (130‐180ºC), feed moisture (14.6‐24.5%) and fiber content (0.0‐15.0%) on the physicochemical and structural properties of starch‐derived loose‐fill packaging materials (LFPM). Two blends were analyzed: one of corn starch and henequen fiber (Agave americana) (CS‐HF), and the other of potato starch and coconut fiber (PS‐CF). An experimental laboratory extruder with a 2.9 mm internal diameter die‐nozzle was used, and a hybrid central composite design was employed to study the LFPM, and the influence of some extrusion variables on mechanical properties, i.e. tensile strength (ϵ),stress (σ), flexion modulus (E_f), and structural properties; expansion index (EI), water absorption capacity (WAC), crystallinity by X‐ray diffraction, viscosity profiles and scanning electronic microscopy (SEM). In both extruded blends feed moisture was the most significant variable, increasing the values of EI and ϵ, and decreasing the values of σ and E_f when the feed moisture was decreased. The blend of PS‐CF had the highest values of EI, ϵ, σ and E_f,, and is the more appropriate for the preparation of LFPM. X‐ray diffraction analysis of the LFPM samples suggested the formation of almost completely amorphous structures, similar to those of commercial LFPM prepared from polystyrene. This research indicated that blends from natural sources like corn starch with henequen, and potato starch with coconut fibers have the potential to be used in the preparation of LFPM with similar characteristics to commercial LFPM, with the additional advantage of being biodegradable.