Automotive can network response time analysis with variable jitter

Many methods to calculate message latencies for Controller Area Network (CAN) have previously been presented based upon the static worst-case behaviour of the system. With the use of modern simulation tools however, the behaviour of CAN networks can be simulated dynamically in order to find the likely worst-case response times for CAN messages. This paper shows the development of an automotive body control network model to be used as the basis for further simulations. A method to simulate the Worst-Case Response Time of this model is then presented, taking into account random queuing jitter.

An analysis of update ordering in distributed replication systems

This paper analyses update ordering and its impact on the performance of a distributed replication system. We propose a model for update orderings and constraints and develop a number of algorithms for implementing different ordering constraints. A performance study is then carried out to analyse the update-ordering model. We show that our model allows the definition of an ordering constraint on each update operation, and the ordering implementation takes account of detailed inter-operation semantics denoted by commutative operations and causal operations to reduce unnecessary delay and results in a better response time for update requests.

Preemptive job scheduling policy for distributively-owned workstation clusters

Cluster computing has come to prominence as a cost-effective parallel processing tool for solving many complex computational problems. In this paper, we propose a new timesharing opportunistic scheduling policy to support remote batch job executions over networked clusters to be used in conjunction with the Condor Up-Down scheduling algorithm. We show that timesharing approaches can be used in an opportunistic setting to improve both mean job slowdowns and mean response times with little or no throughput reduction. We also show that the proposed algorithm achieves significant improvement in job response time and slowdown as compared to exiting approaches and some recently proposed new approaches.

Non-equivalence of direct and indirect measures of unrealistic optimism

Individuals typically believe that they are less likely than the average person to experience negative events. Such “unrealistic optimism” (UO) has been assessed in two ways: directly (via a single question, requiring comparison of own risk to that of the average person) and indirectly (via separate questions about own risk and that of the average person). The study examined the equivalence of the direct and indirect measures of female students' UO for unwanted pregnancy. Participants (N = 120) answered questions about their own risk, that of the average female student, and their own risk relative to that of the average female student; responses and response times were recorded. There was only a moderate association between direct- and indirect-UO. Direct-UO was strongly associated with estimate of own risk, but only moderately associated with estimate of the average student's risk. Response times for the comparative risk and own risk questions did not differ, but participants took significantly longer to answer the question about average student's risk. The results suggest that the two measures of UO are not equivalent, but, rather, that individuals answering a comparative risk question focus mainly on their own risk, at the expense of that of the average person.

Gait termination : a review of experimental methods and the effects of aging and gait pathologies

The study of human gait has expanded and diversified to the extent that it is now possible to identify a substantive literature concerning a variety of gait tasks, such as gait initiation [Halliday SE, Winter DA, Frank JS, Patla AE, Prince F. The initiation of gait in young, elderly, and Parkinson's disease subjects. Gait Posture 1998;8:8–14; Mickelborough J, van der Linden ML, Tallis RC, Ennos AR. Muscle activity during gait initiation in normal elderly people. Gait Posture 2004;19:50–57], stepping over and across obstacles [Patla AE, Prentice SD, Robinson C, Newfold J. Visual control of locomotion: strategies for changing direction and for going over obstacles. J Exp Psych 1991;17:603–34; Chen, HC, Ashton-Miller JA, Alexander NB, Schultz AB. Effect of age and available response time on ability to step over an obstacle. J Gerontol 1994;49:227–33; Sparrow WA, Shinkfield AJ, Chow S, Begg RK. Gait characteristics in stepping over obstacles. Hum Mov Sci 1996;15:605–22; Begg RK, Sparrow WA, Lythgo ND. Time-domain analysis of foot–ground reaction forces in negotiating obstacles. Gait Posture 1998;7:99–109; Patla AE, Rietdyk S. Visual control of limb trajectory over obstacles during locomotion: effect of obstacle height and width. Gait Posture 1993;1:45–60] negotiating raised surfaces such as curbs and stairs [Begg RK, Sparrow WA. Gait characteristics of young and older individuals negotiating a raised surface: implications for the prevention of falls. J Gerontol Med Sci 2000;55A:147–54; Mcfayden BJ, Winter DA. An integrated biomechanical analysis of normal stair ascent and descent. J Biomech 1988;21:733–44]. In addition, increasing research interest in age-related declines in gait that might predispose individuals to falls has engendered a very extensive literature concerning ageing effects on gait. While rapid locomotor adjustments are common in the course of daily activities there has been no previous review of the findings concerning gait adaptations when walking is terminated both rapidly and unexpectedly. The aims of this review were first, to summarise the key research findings and methodological considerations from studies of termination. The second aim was to demonstrate the effects of ageing and gait pathologies on termination with respect to the regulation of step characteristics, lower-limb muscle activation patterns and foot–ground reaction forces.

Internal representation of movement in children with developmental coordination disorder : a mental rotation task

Recent studies show that children with developmental coordination disorder (DCD) have difficulties in generating an accurate visuospatial representation of an intended action, which are shown by deficits in motor imagery. This study sought to test this hypothesis further using a mental rotation paradigm. It was predicted that children with DCD would not conform to the typical pattern of responding when required to imagine movement of their limbs. Participants included 16 children with DCD and 18 control children; mean age for the DCD group was 10 years 4 months, and for controls 10 years. The task required children to judge the handedness of single-hand images that were presented at angles between 0° and 180° at 45° intervals in either direction. Results were broadly consistent with the hypothesis above. Responses of the control children conformed to the typical pattern of mental rotation: a moderate trade-off between response time and angle of rotation. The response pattern for the DCD group was less typical, with a small trade-off function. Response accuracy did not differ between groups. It was suggested that children with DCD, unlike controls, do not automatically enlist motor imagery when performing mental rotation, but rely on an alternative object-based strategy that preserves speed and accuracy. This occurs because these children manifest a reduced ability to make imagined transformations from an egocentric or first-person perspective.

Pervasive computing at tableside : a wireless web-based ordering system

Purpose – The purpose of this paper is to introduce a wireless web-based ordering system called iMenu in the restaurant industry. Design/methodology/approach – By using wireless devices such as personal digital assistants and WebPads, this system realizes the paradigm of pervasive computing at tableside. Detailed system requirements, design, implementation and evaluation of iMenu are presented.

Findings – The evaluation of iMenu shows it explicitly increases productivity of restaurant staff. It also has other desirable features such as integration, interoperation and scalability. Compared to traditional restaurant ordering process, by using this system customers get faster and better services, restaurant staff cooperate more efficiently with less working mistakes, and enterprise owners thus receive more business profits.

Originality/value – While many researchers have explored using wireless web-based information systems in different industries, this paper presents a system that employs wireless multi-tiered web-based architecture to build pervasive computing systems. Instead of discussing theoretical issues on pervasive computing, we focus on practical issues of developing a real system, such as choosing of web-based architecture, design of input methods in small screens, and response time in wireless web-based systems.

Controller area network (CAN) modelling for automotive body control applications

This research details methods to improve upon current worst-case message response time analysis of CAN networks. Also, through the development of a CAN network model, and using modern simulation software, methods were shown to provide more realistic analyses of both sporadic and periodic messages on CAN networks prior to implementation.

Transaction management in a replicated and mobile environment

Reports the design of three-level transaction processing model which provides efficient transaction management in a replicated and mobile environment. The model uses a promary/non-primary replication control protocol to enable transaction processing with fast user response time at any distributed site including mobile hosts. A Web-based design with an implementation of a prototype application system shows a concrete example of how to adopt the transaction model over distributed databases.

Energy-efficient management of data center resources for cloud computing : a vision, architectural elements, and open challenges

Cloud computing is offering utility-oriented IT services to users worldwide. Based on a pay-as-you-go model, it enables hosting of pervasive applications from consumer, scientific, and business domains. However, data centers hosting Cloud applications consume huge amounts of energy, contributing to high operational costs and carbon footprints to the environment. Therefore, we need Green Cloud computing solutions that can not only save energy for the environment but also reduce operational costs. This paper presents vision, challenges, and architectural elements for energy-efficient management of Cloud computing environments. We focus on the development of dynamic resource provisioning and allocation algorithms that consider the synergy between various data center infrastructures (i.e., the hardware, power units, cooling and software), and holistically work to boost data center energy efficiency and performance. In particular, this paper proposes (a) architectural principles for energy-efficient management of Clouds; (b) energy-efficient resource allocation policies and scheduling algorithms considering quality-of-service expectations, and devices power usage characteristics; and (c) a novel software technology for energy-efficient management of Clouds. We have validated our approach by conducting a set of rigorous performance evaluation study using the CloudSim toolkit. The results demonstrate that Cloud computing model has immense potential as it offers significant performance gains as regards to response time and cost saving under dynamic workload scenarios.

Towards autonomous image fusion

Mobile robots are providing great assistance operating in hazardous environments such as nuclear cores, battlefields, natural disasters, and even at the nano-level of human cells. These robots are usually equipped with a wide variety of sensors in order to collect data and guide their navigation. Whether a single robot operating all sensors or a swarm of cooperating robots operating their special sensors, the captured data can be too large to be transferred across limited resources (e.g. bandwidth, battery, processing, and response time) in hazardous environments. Therefore, local computations have to be carried out on board the swarming robots to assess the worthiness of captured data and the capacity of fused information in a certain spatial dimension as well as selection of proper combination of fusion algorithms and metrics. This paper introduces to the concepts of Type-I and Type-II fusion errors, fusion capacity, and fusion worthiness. These concepts together form the ladder leading to autonomous fusion systems.

Efficient resource selection algorithm for enterprise grid systems

This paper addresses a resource selection problem for applications that update data in enterprise grid systems. The problem is insufficiently addressed as most of the existing resource selection approaches in grid environments primarily deal with read-only job. We propose a simple yet efficient algorithm that deals with the complexity of resource selection problem in enterprise grid systems. The problem is formulated as a Multi Criteria Decision Making (MCDM) problem. Our proposed algorithm hides the complexity of resource selection process without neglecting important components that affect job response time. The difficulty on estimating job response time is captured by representing them in terms of different QoS criteria levels at each resource. Our experiments show that the proposed algorithm achieves very good results with good system performance as compared to existing algorithms.