Fault-tolerant servers for anycast communication

Plenty of research has been done for any cast service, but few research touches the fault-tolerant problem based on the best of our knowledge. In this paper, we propose and analyse a fault-tolerant model, called twin server model, for anycast communication to provide reliable and continuous anycast services. We select a twin server in an anycast group for a given anycast server, the primary server. If the twin server suspects that its primary server is dead, it will take the unfinished job(s) of its primary server. We propose two algorithms: the server failure detecting algorithm and the server failure broadcasting algorithm. We then analyse the performance change when a primary server fails using queue theory and obtain some interesting conclusions. At the end, we summary the paper and present the future work.

The influence of housing size, style and location on energy and greenhouse gas emissions

Concern about the growth of greenhouse gas emissions in Victoria has prompted the introduction of legislation to improve the thermal performance of the residential building envelope. Unfortunately, the size of the house is not considered in the rating tool that underpins the legislation. The energy embodied in the constructional materials is also not considered although it too is directly related to the size of the house. Another intrinsic factor relating residential housing energy and greenhouse gas emissions is the location of the residence and the travel preferences of the homeowner. The relationship between the operational, embodied and travel energy associated with a typical residential scenario in Melbourne over the last 50 years is examined in this paper. The analysis found that by the year 2000, the energy associated with work-related travel (44%) now exceeds the operational energy (37%). In terms of greenhouse gas emissions, the contribution from travel energy is almost double that from operational energy (28%).

Robust extended kalman filter applied to location tracking and trajectory prediction for PCS networks

Provisioning of real-time multimedia sessions over wireless cellular network poses unique challenges due to frequent handoff and rerouting of a connection. For this reason, the wireless networks with cellular architecture require efficient user mobility estimation and prediction. This paper proposes using robust extended Kalman filter (REKF) as a location heading altitude estimator of mobile user for next cell prediction in order to improve the connection reliability and bandwidth efficiency of the underlying system. Through analysis we demonstrate that our algorithm reduces the system complexity (compared to existing approach using pattern matching and Kalman filter) as it requires only two base station measurements or only the measurement from the closest base station. Further, the technique is robust against system uncertainties due to inherent deterministic nature in the mobility model and more effective in comparison with the standard Kalman filter.

Location, location, location: exploring the importance of place for arts organisations

Many arts managers and marketers are looking intently at the importance of high-speed communication and other technologies for the creation of virtual places. These places in cyberspace can only be accessed via a computer terminal and high-speed telecommunications tools. This paper asserts that there is still much for managers and marketers to learn about the importance of physical spaces for the arts. We use a model of place and apply it to three Australian arts organisations located in heritage buildings. One organisation failed, the other changed ownership, the third moved location. The findings demonstrate the importance of place and of strategy in determining place. We note the tension between the strategy, the venue, the objects, and the essential task and call for further analysis of place(s) for the arts.

Location based power control for mobile devices in a cellular network

This paper provides location estimation based power control strategy for cellular radio systems via a location based interference management scheme. Our approach considers the carrier-to-interference as dependent on the transmitter and receiver separation distance and therefore an accurate estimation of the precise locations can provide the power critical mobile user to control the transition power accordingly. In this fully
distributed algorithms, we propose using a Robust Extended Kalman Filter (REKF) to derive an estimate of the mobile user’s closest mobile base station from the user’s location, heading and altitude. Our analysis demonstrates that this algorithm can successfully track the mobile users with less system complexity, as it requires measurements from only one or two closest mobile base stations and hence enable the user to transmit at the rate that is sufficient for the interference management. Our power control
algorithms based on this estimation converges to the desired power trajectory. Further, the technique is robust against system uncertainties caused by the inherent deterministic nature of the mobility model. Through simulation, we show the accuracy of our prediction algorithm and the simplicity of its implementation.

Location based power control for energy critical sensors in a disconnected network

This paper provides a location based power control strategy for disconnected sensory nodes deployed for long term service. Power conservation is of importance particularly when sensors communicate with a mobile robot used for data collection. The proposed algorithm uses estimations from a Robust Extended Kalman Filter (REKF) with RSSI measurements, in implementing a sigmoid function based power control algorithm which essentially approaches a desired power emission trajectory based on carrier-to-interference ratios(CIR) to ensure interferenceless reception. The more realistic modelling we use incorporates physical dynamics between the mobile robot and the sensors together with the wireless propagation parameters between the transmitter and receiver to formulate a sophisticated and effective power control strategy for the exclusive usage of energy critical disconnected nodes in a sensory network increasing their life span.

A discussion on passive location discovery in emitter networks using angle-only measurements

In this paper we discuss the ghost node problem found when triangulation of 2 or more nodes is required. We present and discuss a simple algorithm, termed ABLE (Angle Based Location Estimation), that will position randomly placed emitters in a wireless sensor network using a mobile antenna array. The individual nodes in the network are relieved of the localization task by the mobile antenna system and require no modifications to account for location determination. Furthermore, no beacon nodes (i.e. nodes that know their own position) are required. We provide analysis that indicates a reasonably small number of measurements are required to guarantee the successful
localization of the emitting nodes and demonstrate our results through simulation.

The effect of hook/bait size and angling technique on the hooking location and the catch of recreationally caught black bream Acanthopagrus butcheri

The black bream Acanthopagrus butcheri recreational fishery is the largest estuarine fishery in Victoria. This fishery is managed through legal-minimum length and daily bag limits. The success of this management strategy requires a high survival rate for released fish. Deep-hooking is known to reduce the chance of fish survival after recreational capture and release. This study investigated the potential to reduce deep-hooking and the number of under-size A. butcheri caught by varying angling gear and techniques. Three sizes of long shank hook (small [size 8], medium [size 4] and large [size 1/0]) and two angling techniques (slack line and tight line) were tested for their deep-hooking rates and selectivity characteristics. Increasing the hook size from small to large decreased the likelihood of deep-hooking by 6.6 times (95% CI 2.3–16.3 times). Fishing with a tight line instead of a slack line decreased the chance of deep-hooking by almost 100% (95% CI 0.8–3.6). Fishing with a large hook instead of a small hook significantly (F = 6.71, df = 2, P = <0.001) increased the mean A. butcheri length, although this mean size increase was less than 1 cm. This study was able to identify angling gear and angling technique manipulations that reduced the rate of deep-hooking when targeting A. butcheri in Victorian estuaries.

Taxonomy and survey of location management systems

In wireless mobile computing, location management is introduced whenever users move from one place to another. In order to track a mobile user, the system must store information about their current location and report new locations to a home base station. Numerous techniques have been proposed to optimally manage the location of mobile hosts in mobile networks. This paper attempts to present a more structured and comprehensive analysis of the current location management techniques architectures and their technology enablers. We discuss some of the principal issues involved in location management and present a taxonomy and survey of location management strategies that have been proposed in the literature over the years for mobile computing systems.

A reactive system architecture for building fault-tolerant distributed applications

Most fault-tolerant application programs cannot cope with constant changes in their environments and user requirements because they embed policies and mechanisms together so that if the policies or mechanisms are  changed the whole programs have to be changed as well. This paper presents a reactive system approach to overcoming this limitation. The reactive system concepts are an attractive paradigm for system design, development and maintenance because they separate policies from mechanisms. In the paper we propose a generic reactive system architecture and use group communication primitives to model it. We then implement it as a generic package which can be applied in any distributed applications. The system performance shows that it can be used in a distributed environment effectively.

Associations of location and perceived environmental attrubutes with walking in neighborhoods

Purpose. Ecological models highlight the importance of environmental influences. We examined associations of coastal versus noncoastal location and perceived environmental attributes with neighborhood walking, total walking, and total activity.

Methods. Telephone interviews with 800 faculty and general staff of an Australian university.

Results. Men were significantly more likely to walk in their neighborhood if they lived in a coastal location (odds ratio [OR] = 1.66), and they highly rated environmental "aesthetics" (OR = 1.91), "convenience" of facilities (OR = 2.20), and "access" to facilities (OR = 1.98). For women, neighborhood walking was associated with high ratings of "convenience" (OR = 3. 78) but was significantly less likely if they had high ratings for "access" (OR = 0.48). For total walking and total physical activity, few significant associations emerged.

Conclusions. Environmental attributes were related to walking in the neighborhood but not to more general activity indices. Understanding gender-specific environmental correlates of physical activity should be a priority. Key Words: Walking; Physical Activity; Environment; Perceptions; Prevention.

Mobile location based services

Mobility has become a key factor around the world, as the use of ubiquitous devices, including laptops, personal digital assistants (PDAs), and mobile phones, are increasingly becoming part of daily life (Steinfield, 2004). Adding mobility to computing power, and with advanced personalization of technologies, new business applications are emerging in the area of mobile communications (Jagoe, 2003). The fastest growing segment among these applications is location-based services. This article offers a brief overview of services and their supporting technologies, and provides an outlook for their future.