Using mobile agents to recover from node and database compromise in path-based DoS attacks in wireless sensor networks

Wireless sensor networks represent a new generation of real-time embedded systems with significantly different communication constraints from the traditional networked systems. With their development, a new attack called a path-based DoS (PDoS) attack has appeared. In a PDoS attack, an adversary, either inside or outside the network, overwhelms sensor nodes by flooding a multi-hop end-to-end communication path with either replayed packets or injected spurious packets. Detection and recovery from PDoS attacks have not been given much attention in the literature. In this article, we consider wireless sensor networks designed to collect and store data. In a path-based attack, both sensor nodes and the database containing collected data can be compromised. We propose a recovery method using mobile agents which can detect PDoS attacks easily and efficiently and recover the compromised nodes along with the database.

Australia and New Zealand: separate states but path-dependent

Australia and New Zealand (Aotearoa) have shared almost two centuries of close relations created through close geographic proximity, shared membership of political associations, and frequent policy exchange. The relevant context has shifted from the British Empire and Commonwealth to a rapidly globalizing world under US military hegemony. Australia and New Zealand were among the early settler colonies of the British Empire and this article argues that, as such, the settler colonies helped shape the form of the Empire, and subsequently the Commonwealth. This history created strong, separate, if somewhat similar, traditions of independent political experimentation. This article explores different models for explaining the cross-Tasman relationship and concludes that the path-dependent approach works best. The path was also influenced by external shocks, notably the second world war and Britain's moves towards Europe, and it was these shocks that created the necessary ruptures to create change. The first world war had catapulted Australia and New Zealand towards separate nationhood, and simultaneously strengthened their cultural and political links. The second world war pushed Australia towards the USA and led both Australia and New Zealand to develop a more explicit role as regional leaders in the Pacific. For New Zealand, Britain's membership of the European Community created an economic crisis and politico-cultural stresses which are reverberating still. Such shocks created the preconditions also for closer association, exemplified in the CER Treaty, which in turn draws upon historical precedents and experiences.

Corporate sustainability : greenwash or a path to sustainable capitalism?

The problems of unsustainable development and the increased-awareness of corporate power in the global era have contributed to an agenda of corporate citizenship. This thesis explores the meanings and practices that fall under the banner of the triple bottom line of corporate citizenship through forty-two in-depth interviews with representatives from the corporate sector and NGO sector (including trade unions) in Australia. This purposive sample includes a specific range of corporate industries and NGO types, all of which have involvement with various areas of sustainability. Interviewees described their feelings and experiences in relation to the concept of the triple bottom line, the potential and limitations of this type of sustainability and the purpose and impacts of partnerships between NGOs and the corporate sector. On the basis of this research, this thesis argues that corporate citizenship is at best, a set of initiatives for making minor adjustments to the way companies perform their day-to-day operations and at worst, a program for improving corporate image rather than performance and for shifting the agenda of sustainable development toward corporate interests. While radical steps are required to achieve a sustainable society and environment, the terms of corporate citizenship offer very limited opportunities for change. The self-regulatory and market based model of citizenship does not challenge the impact of consumerism or the legitimacy of particular industry types and their products, except where threats are perceived to the longevity of the companies involved. Furthermore, while the exploitation of the environment and society has occurred as a result of corporate self-interest, corporate citizenship is justified on the same basis. The self-interest rationale and the tyranny of the economic bottom line in particular, substantially limit the fields of responsibility that can be included in the citizenship paradigm. While there are undoubtedly some well-intentioned corporate representatives who are working toward attaining a more sustainable corporate culture, the discourse is primarily used to shift the sustainable development agenda toward corporate paradigms and interests.

Keeping all students on the learning path

A powerful notion to guide thinking about whole-class mathematics teaching is Vygotsky’s zone of proximal development (ZPD). Our research with primary and secondary teachers over the last six years has identified roles of teachers in relation to the ZPD, and ways of overcoming some typical barriers to students’ movement through their zones. Methods have included focus groups of experts, video analysis of classroom interactions, classroom observation, and analysis of lesson plans and teachers’ reflections teaching processes their outcomes. The research has involved the gradual development, trailing, evaluation, and adjustment of a six-component model for planning and teaching mathematics. The focus of this paper is on the use of one of its components, “differentiated learning trajectories”.

Effect of cold drawing on subsequent surface strain path and ductility during upsetting

Cold drawing is a process that sizes and smooths the surface of steel before it is cold headed to produce bolts. The effect of the changes in the mechanical properties due to cold drawing on the surface strain and ductility during the upsetting process was analysed showing that the stress and strain state can be more readily altered by changes in the process conditions (friction and height-to-diameter ratio) to cause greater increase in the failure strains than can be achieved by pre-drawing.

Factors affecting SMEs' willingness to share knowledge online : a path model

This paper presents the findings of a study of SME owner-managers that examined their willingness to share information online with other members of a local business network. The main variables associated with willingness to share knowledge online were found to be willingness to share information in conventional modes and the intensity with which they used the internet for business activities. A number of other variables were found to be indirectly or unrelated to willingness to share knowledge online. A significant locality effect was also identified which suggests that the social context of the network to which the business belonged influences willingness to share knowledge online. Our work supports previous research which concludes that online knowledge sharing initiatives should enhance relationships within the business network itself as well as the technical aspects of the networking platform and the technical competence of potential users.

The relationship between emergence of the shortest path and information value using ant-like agents

Ant-like agents forage between two points. These agents' probabilistic movements are based on the use of two pheromones; one marking trails towards the goal and another marking trails back to the starting point. Path selection decisions are influenced by the relative levels of attractive and repulsive pheromone in each agent's local environment. Our work in [5] evaluates three pheromone perception strategies, investigating path formation speed, quality, directionality, robustness and adaptability under different parameter settings(degree of randomness, pheromone evaporation rate and pheromone diffusion rate). We re-evaluate two of these strategies in terms of the amount of information they provide using Shannon's formulation [3, 4, 8, 9, 12, 14, 15, 16, 17]. We determine information as the difference between uncertainty before and after path selection decisions. Our focus in this paper is on investigating relationships between the emergence of the shortest path and the amount of stigmergic information that exists in the form of pheromone. Agents are deployed centrally and emergence measures are determined using the worst, reference and best cases observed in [5]. Additionally, the amount of local and global information that is available to agents in each movement step is evaluated. Furthermore, Pearson's correlation coefficients between measures of emergence and the amount of information are calculated. The significance of these correlation coefficients is tested using a 2 tailed test at 1% level of significance. Consequently the relationship between the amount of information and emergent behaviour is established. Significant relationships between information and the emergence of the shortest path exist when strong emergent behaviour is present.

A probabilistic movement model for shortest path formation in virtual ant-like agents

We propose a probabilistic movement model for controlling ant-like agents foraging between two points. Such agents are all identical, simple, autonomous and can only communicate indirectly through the environment. These agents secrete two types of pheromone, one to mark trails towards the goal and another to mark trails back to the starting point. Three pheromone perception strategies are proposed (Strategy A, B and C). Agents that use strategy A perceive the desirability of a neighbouring location as the difference between levels of attractive and repulsive pheromone in that location. With strategy B, agents perceive the desirability of a location as the quotient of levels of attractive and repulsive pheromone. Agents using strategy C determine the product of the levels of attractive pheromone with the complement of levels of repulsive pheromone. We conduct experiments to confirm directionality as emergent property of trails formed by agents that use each strategy. In addition, we compare path formation speed and the quality of the formed path under changes in the environment. We also investigate each strategy's robustness in environments that contain obstacles. Finally, we investigate how adaptive each strategy is when obstacles are eventually removed from the scene and find that the best strategy of these three is strategy A. Such a strategy provides useful guidelines to researchers in further applications of swarm intelligence metaphors for complex problem solving.

Policy trajectories : treading the discursive path of policy analysis

This paper is concerned with theorising the nature of policy and its production. It takes as its starting point the work of Stephen Ball,1 particularly his writings within the pages of this journal (13(2), 1993)—later reprinted as Chapter 2 in Education Reform (1994a)—as well as his earlier writings in Politics and Policy Making in Education (1990) and Reforming Education and Changing Schools (Bowe, Ball & Gold, 1992). More broadly, the paper is located within a 'new' sociological interest in education policy often referred to as 'policy sociology'2 (Payne, Dingwall, Payne & Carter, 1981; Ozga, 1987, Ball, 1990; Bowe, Ball & Gold, 1992); a concern that is 'rooted in the social science tradition, historically informed and drawing on qualitative and illuminative techniques' (Ozga, 1987, p. 144) and 'united by the conviction that "things", especially policy discourse, must be pulled apart' (Troyna, 1994, p. 71) to determine whose interests they serve.

An adjustable force field for multiple robot mission and path planning

Mission and path planning for multiple robots in dynamic environments is required when multiple mobile robots or unmanned vehicles are used for geographically distributed tasks. Assigning tasks and paths for robots for cooperatively accomplishing a mission of reaching to number of target points are addressed in this paper. The methodology that is proposed is based on using an adjustable force field which is suitable for dynamic environment. From the force field analysis, the decisions to assign tasks for each robot are then made. The force field is also used to plan a collision free path for each robot. Adjustable weights for the force field model are proposed to satisfy the constraints of the motion. In this research, the constraints are the cooperation of the robots, the precedence between the targets and between robots, and the discrimination between different obstacles. Two simulations for mission and path planning in 2D and 3D dynamic spaces with multiple robots are presented based on the proposed adjustable force filed. The result of the mission and path planning for three robots cooperatively doing eight target points are shown.