Dynamic iterative ontology learning

The fundamental failure of current approaches to ontology learning is to view it as single pipeline with one or more specific inputs and a single static output. In this paper, we present a novel approach to ontology learning which takes an iterative view of knowledge acquisition for ontologies. Our approach is founded on three open-ended resources: a set of texts, a set of learning patterns and a set of ontological triples, and the system seeks to maintain these in equilibrium. As events occur which disturb this equilibrium, actions are triggered to re-establish a balance between the resources. We present a gold standard based evaluation of the final output of the system, the intermediate output showing the iterative process and a comparison of performance using different seed input. The results are comparable to existing performance in the literature.

Effects of dynamic strain ageing on fatigue crack propagation and threshold behaviour in a Ni-base superalloy

In the temperature range 200-400 degree C the Ni-base superalloy, N901, develops marked dynamic strain ageing effects in its tensile behavior. These include inverse strain rate sensitivity, especially in UTS values, strongly serrated stress-strain curves and a heavily sheared failure mode at the higher test-temperatures. As for steels these effects seem to be due to interactions between the dislocations and the interstitial carbon atoms present. The results of tensile and fatigue threshold tests carried out between 20 degree C and 420 degree C are reported and the fatigue behavior is discussed in terms of the effects of surface roughness induced closure, temperature and strain aging interactions.

Serrated yielding and the localized shear failure mode in aluminium alloys

A study has been made of serrated yielding in two commercial Al-Zn-Mg alloys in the as-quenched condition. The different serration types produced in the two alloys and the shear failure mechanism observed in both notched-bend and tensile testing are related to the mechanisms of dynamic strain ageing occurring during the test. An estimate of 19.7 kJ/mole for the activation energy for exchange of a solute atom and a vacancy in Al-6.2 wt% Zn, 2.5 wt% Mg has been made. © 1981.

Using the max-sum algorithm for supply chain emergence in dynamic multiunit environments

Supply chain formation (SCF) is the process of determining the set of participants and exchange relationships within a network with the goal of setting up a supply chain that meets some predefined social objective. Many proposed solutions for the SCF problem rely on centralized computation, which presents a single point of failure and can also lead to problems with scalability. Decentralized techniques that aid supply chain emergence offer a more robust and scalable approach by allowing participants to deliberate between themselves about the structure of the optimal supply chain. Current decentralized supply chain emergence mechanisms are only able to deal with simplistic scenarios in which goods are produced and traded in single units only and without taking into account production capacities or input-output ratios other than 1:1. In this paper, we demonstrate the performance of a graphical inference technique, max-sum loopy belief propagation (LBP), in a complex multiunit unit supply chain emergence scenario which models additional constraints such as production capacities and input-to-output ratios. We also provide results demonstrating the performance of LBP in dynamic environments, where the properties and composition of participants are altered as the algorithm is running. Our results suggest that max-sum LBP produces consistently strong solutions on a variety of network structures in a multiunit problem scenario, and that performance tends not to be affected by on-the-fly changes to the properties or composition of participants.

State–society relations in a dynamic framework:the case of the Far East and Sub-Saharan Africa

According to the textbook approach, the developmental states of the Far East have been considered as strong and autonomous entities. Although their bureaucratic elites have remained isolated from direct pressures stemming from society, the state capacity has also been utilised in order to allocate resources in the interest of the whole society. Yet, society – by and large –has remained weak and subordinated to the state elite. On the other hand, the general perception of Sub-Saharan Africa (SSA) has been just the opposite. The violent and permanent conflict amongst rent-seeking groups for influence and authority over resources has culminated in a situation where states have become extremely weak and fragmented, while society – depending on the capacity of competing groups for mobilising resources to organise themselves mostly on a regional or local level (resulting in local petty kingdoms) – has never had the chance to evolve as a strong player. State failure in the literature, therefore, – in the context of SSA – refers not just to a weak and captured state but also to a non-functioning, and sometimes even non-existent society, too. Recently, however, the driving forces of globalisation might have triggered serious changes in the above described status quo. Accordingly, our hypothesis is the following: globalisation, especially the dynamic changes of technology, capital and communication have made the simplistic “strong state–weak society” (in Asia) and “weak state–weak society” (in Africa) categorisation somewhat obsolete. While our comparative study has a strong emphasis on the empirical scrutiny of trying to uncover the dynamics of changes in state–society relations in the two chosen regions both qualitatively and quantitatively, it also aims at complementing the meaning and essence of the concepts and methodology of stateness, state capacity and state-society relations, the well-known building blocks of the seminal works of Evans (1995), Leftwich (1995), Migdal (1988) or Myrdal (1968).