Tolling, Capacity Selection and Equilibrium Problems with Equilibrium Constraints

An Equilibrium problem with an equilibrium constraint is a mathematical construct that can be applied to private competition in highway networks. In this paper we consider the problem of finding a Nash Equilibrium regarding competition in toll pricing on a network utilising 2 alternative algorithms. In the first algorithm, we utilise a Gauss Siedel fixed point approach based on the cutting constraint algorithm for toll pricing. In the second algorithm, we extend an existing sequential linear complementarity approach for finding Nash equilibrium subject to Wardrop Equilibrium constraints. Finally we consider how the equilibrium may change between the Nash competitive equilibrium and a collusive equilibrium where the two players co-operate to form the equivalent of a monopoly operation

Market Information Services

Information is the lifeblood of most market economies. Nevertheless, attempts to jump start information flow by creating Market Information Services for food and agriculture usually fail. The author distills experiences and lessons from other studies and individual experts in the field on the reasons for such common failures and what can be done to avoid them. Critical topics such as institutional structure, dissemination methods, and funding are outlined to guide the reader through the basic issues that must be addressed in order to create a successful Market Information Service.Market Information Service; market data; price information; trade information; developing countries; marketing; agriculture, food, institutions, Market Information System

Toward an efficient solution for dynamic ad hoc network interoperability

An ad hoc network is formed by an impromptu grouping of network capable nodes. The nodes forming the network have unconstrained mobility, and so provide a dynamic network topology. Current work in this research area has focused on designing routing protocols capable of efficiently forwarding packets in these dynamic network environments. This has led to several designs for ad hoc routing protocols based on various routing algorithms, each suited to specific usage characteristics. This paper will discuss issues relating to routing in ad hoc networks. We will describe an active networking based solution that provides dynamic routing protocol interoperability and enables migration of nodes between ad hoc groups. Our design is motivated by a squad and base scenario which consists of two groups wishing to communicate. These groups have contrasting deployment characteristics and so use different routing protocols

A mechanistic analysis of naphthenate and carboxylate soap-forming systems in oilfield exploration and production

This project entailed mechanistic aspects of the formation of oilfield soaps. An integrated approach to the study of field deposits was developed leading to an optimised analytical protocol which is one of the major contributions of this thesis. The philosophy behind the choice of techniques was to integrate measurements suitable for bulk and surface properties. The selected and optimised techniques were electrospray mass spectrometry (ES), energy dispersive X-ray (EDAX) and solid state 13C nuclear magnetic resonance (NMR) as well as thermal analysis (TGA/DSC) and interfacial tension (IFT). These allowed for the differentiation of the two end-member types of soaps, namely, calcium naphthenate soap scales and sodium carboxylate soap emulsions, as well as for the identification of chemically-treated deposits and asphaltenes. It was concluded that the analysis of naphthenic acids from field soap deposits in mass spectrometry was a function of: ionisation source, solvent and instrument settings (e.g. voltages). These parameters had a direct effect on the relative detection of particular naphthenic acid species such as the Arn. Though the electrospray (ES) source was observed to lead to a more realistic fingerprint for naphthenic acid extracts, it was also suggested that the atmospheric pressure chemical ionisation (APCI) source could be used in conditions where identification of Arn was the ultimate objective. A series of static bottle tests were devised to simulate the pH changes associated with the occurrence of deposits in the field. The procedures focused on a number of model naphthenic acid systems, as well as acids extracted from field deposits and soap-forming crude oils. Soap formation was found to be a function of the precise aqueous phase (e.g. cations and pH) in addition to the oil phase (e.g. acyclic vs. cyclic/aromatic naphthenic acid content). It was possible to form soap deposits in the laboratory from both indigenous acids, as well as crude oils. Detailed speciation of certain indigenous acids allowed for the identification of Arn and the special properties of this species namely: four carboxylic acid groups by tandem mass spectrometry (MS/MS) and surface properties given by interfacial tension (IFT). Previous literature claims stated that Arn acid presence were solely responsible for the precipitation of calcium naphthenate soap scales. The results in this thesis show that although Arn acids have predominant surface properties, they compete with lower molecular weight acids for aqueous phase cations at high pH values. This was observed in static bottle tests as well as results from field precipitation samples. Fourier-Transform infrared (FTIR) spectroscopy showed potential as a technique for the prediction of soap deposition onset in the laboratory. Supporting experiments were designed to validate a simple thermodynamic model to predict the phase iii behaviour of oil-water-naphthenic acid systems. A sensitivity study showed that the dissociation constants (pKa) of the naphthenic acids were the most important model parameters and could affect predicted output pH values. For indigenous naphthenic acids, alternative procedures for both dissociation constant and partition coefficient were introduced. A comprehensive suite of crude oil analysis and water properties were employed for correlating field soap-forming systems. It was possible to obtain some trends which relate geochemical parameters with bulk crude oil properties, as well as naphthenic acid speciation. Based on this information, a preliminary attempt to establish prediction guidelines for soaps, one of the major contributions in this thesis to the current knowledge of soap-forming systems, is presented.EPRS

Tolling, collusion and equilibrium problems with equilibrium constraints

An Equilibrium Problem with an Equilibrium Constraint (EPEC) is a mathematical construct that can be applied to private competition in highway networks. In this paper we consider the problem of finding a Nash Equilibrium in a situation of competition in toll pricing on a network utilising two alternative algorithms. In the first algorithm, we utilise a Gauss Seidel fixed point approach based on the cutting constraint algorithm for toll pricing. The second algorithm that we propose, a novel contribution of this paper, is the extension of an existing sequential linear complementarity programming approach for finding the competitive Nash equilibrium when there is a lower level equilibrium constraint. Finally we develop an intuitive approach to represent collusion between players and demonstrate that as the level of collusion goes from none to full collusion so the solution maps from the Nash to monopolistic solution. However we also show that there may be local solutions for the collusive monopoly which lie closer to the second best welfare toll solution than does the competitive Nash equilibrium

First record of an Odontaspidid shark in Ascension Island waters

The occurrence of the poorly understood shark species Odontapsis ferox is reported at an oceanic seamount in the central south Atlantic, within the Exclusive Economic Zone of Ascension Island. The presence of the species at this location is confirmed by the discovery of a tooth embedded in scientific equipment, and footage of at least one animal on autonomous underwater video. The new record of this shark species at this location demonstrates the knowledge gaps which still exist at many remote, oceanic structures and their candidacy for status as important conservation areas.info:eu-repo/semantics/publishedVersio