MetaCDN: Harnessing ‘Storage Clouds’ for high performance content delivery

Content delivery networks (CDNs) such as Akamai and Mirror Image place web server clusters in numerous geographical locations to improve the responsiveness and locality of the content it hosts for end-users. However, their services are priced out of reach for all but the largest enterprise customers. An alternative approach to content delivery could be achieved by leveraging existing infrastructure provided by ‘Storage Cloud’ providers, who offer internet accessible data storage and delivery at a fraction of the cost. In this paper, we introduce MetaCDN, a system that exploits ‘Storage Cloud’ resources, creating an integrated overlay network that provides a low cost, high performance CDN for content creators. MetaCDN removes the complexity of dealing with multiple storage providers, by intelligently matching and placing users’ content onto one or many storage providers based on their quality of service, coverage and budget preferences. MetaCDN makes it trivial for content creators and consumers to harness the performance and coverage of numerous ‘Storage Clouds’ by providing a single unified namespace that makes it easy to integrate into origin websites, and is transparent for end-users. We then demonstrate the utility of this new approach to content delivery by showing that the participating ‘Storage Clouds’ used by MetaCDN provide high performance (in terms of throughput and response time) and reliable content delivery for content consumers, whilst the MetaCDN system itself introduces minimal overhead compared to using these ‘Storage Clouds’ directly.     

Tradeoffs between energy consumption and QoS in mobile grid

Mobile grid, which combines grid and mobile computing, supports mobile users and resources in a seamless and transparent way. However, mobility, QoS support, energy management, and service provisioning pose challenges to mobile grid. The paper presents a tradeoff policy between energy consumption and QoS in the mobile grid environment. Utility function is used to specify each QoS dimension; we formulate the problem of energy and QoS tradeoff by utility optimization. The work is different from the classical energy aware scheduling, which usually takes the consumed energy as the constraints; our utility model regards consumed energy as one of the components of measure of the utility values, which indicates the tradeoff of application satisfaction and consumed energy. It is a more accurate utility model for abstracting the energy characteristics and QoS requirement for mobile users and resources in mobile grid. The paper also proposes a distributed energy–QoS tradeoff algorithm. The performance evaluation of our energy–QoS tradeoff algorithm is evaluated and compared with other energy and deadline constrained scheduling algorithm.     

Can computers carry content ‘inexplicitly’?

I examine whether it is possible for content relevant to a computer's behavior to be carried without an explicit internal representation. I consider three approaches. First, an example of a chess playing computer carrying emergent content is offered from Dennett. Next I examine Cummins response to this example. Cummins says Dennett's computer executes a rule which is inexplicitly represented. Cummins describes a process wherein a computer interprets explicit rules in its program, implements them to form a chess-playing device, then this device executes the rules in a way that exhibits them inexplicitly. Though this approach is intriguing, I argue that the chess-playing device cannot exist as imagined. The processes of interpretation and implementation produce explicit representations of the content claimed to be inexplicit. Finally, the Chinese Room argument is examined and shown not to save the notion of inexplicit information. This means the strategy of attributing inexplicit content to a computer which is executing a rule, fails.I wish to thank Fred Dretske, JOhn Perry, and an anonymous reviewer for helpful comments and suggestions. Earlier versions of this paper were read at the American Philosophical Association Pacific Division Meeting in San Francisco in March, 1993, and at the 7th International Conference on Computing and Philosophy in Orlando in August, 1992.     

Visually impaired people and the emerging connected TV: a comparative study of TV and Web applications’ accessibility

With the TV signal digitization and the current market growth of connected TVs, the authors envision the appearance of accessibility barriers to visually impaired persons. The paper addresses the following hypothesis: (1) visually impaired users want to extend their TV usage to explore new TV features; (2) TV applications are in less conformance with accessibility guidelines compared to their Desktop versions. Additionally, the authors wanted to assess whether guideline conformance reflected real TV accessibility problems experienced by users. The methods used for this study included surveys aimed at characterizing the interest of the visually impaired population regarding the use of TV, and specifically of Web applications on TV, an automated accessibility evaluation to compare TV and Desktop versions of the same Web application, to understand their conformance with accessibility guidelines, and a user study where participants with visual impairments were asked to perform some tasks on both versions. From the survey, we confirmed that people with visual disabilities are interested in extra features on their TV. Results from the automated accessibility evaluation show that TV applications are in a significantly better level of conformance with accessibility guidelines. The user study has illustrated that users were unable to complete any task using the TV versions of the applications. The results from these studies demonstrated that the new features that come with connected TVs still have a long way to go in order to be accessible by all. Furthermore, they lead us to concur with other works that automated evaluations are not enough to assess the accessibility of a Web page.     

Geographic ‘Place’ and ‘Community Information’ Preferences

People dynamically structure social interactions and activities at various locations in their environments in specialized types of places such as the office, home, coffee shop, museum and school. They also imbue various locations with personal meaning, creating group ‘hangouts’ and personally meaningful ‘places’. Mobile location-aware community systems can potentially utilize the existence of such ‘places’ to support the management of social information and interaction. However, acting effectively on this potential requires an understanding of how: (1) places and place-types relate to people’s desire for place-related awareness of and communication with others; and (2) what information people are willing to provide about themselves to enable place-related communication and awareness. We present here the findings from two qualitative studies, a survey of 509 individuals in New York, and a study of how mobility traces can be used to find people’s important places in an exploration of these questions. These studies highlight how people value and are willing to routinely provide information such as ratings, comments, event records relevant to a place, and when appropriate their location to enable services. They also suggest how place and place-type data could be used in conjunction with other information regarding people and places so that systems can be deployed that respect users’ People-to-People-to-Places data sharing preferences. We conclude with a discussion on how ‘place’ data can best be utilized to enable services when the systems in question are supported by a sophisticated computerized user-community social-geographical model.     

From Dubins’ car to Reeds and Shepp’s mobile robot

In the paper, a control system with intermediate dynamics between Dubins’ car and Reeds and Shepp’s mobile robot is investigated. Time-limited reachable sets and reachable sets at given time are computed. Families of semipermeable curves that are useful for the detection of jumps of the value function of time-optimal control problem are constructed. Research is partly supported by the Russian Foundation for Fundamental Research under Grants 06-01-00414 and 07-01-96085.     

Remote interspecies interactions: Improving humans and animals’ wellbeing through mobile playful spaces

Play is an essential activity for both humans and animals as it provides stimulation and favors cognitive, physical and social development. This paper proposes a novel pervasive playful environment that allows hospitalized children to participate in remote interspecies play with dogs in a dog daycare facility, while it also allows the dogs to play by themselves with the pervasive system. The aim of this playful interactive space is to help improving both children’s and animal’s wellbeing and their relationships by means of technologically mediated play, while creating a solid knowledge base to define the future of pervasive interactive environments for animals.     

How to block Tor’s hidden bridges: detecting methods and countermeasures

Tor network has been widely used for protecting the privacy of users while accessing various online services. Since Tor can be easily blocked by blacklisting the publicly published Tor relays, the hidden bridges-based blocking-resistance mechanism is designed and implemented in the current Tor network. Any user can subscribe a tuple of three bridges via email, https, twitter etc. However, we have found that there exist high correlations among those published tuples, which can be exploited to effectively detect hidden bridges by monitoring the outbound traffic from a controlled network. When Tor clients try to connect chosen hidden bridges, multiple SYN packets with consecutive source ports will be sent almost simultaneously, destining for different hosts. If any destination IP contained among such packets belongs to a known bridge, all others can then be inferred to be of bridges too. By recording and analyzing a series of traffic segments satisfying the above packet features, the hidden bridges used in a controlled network can be detected and further blocked. According to different available computing and storage resources, we proposed both online and offline detecting methods. Both analytical and simulation results verify the high correlation among published bridge tuples, validating the feasibility of our methods. By configuring optimized detecting parameters in the real-world experiments, we can achieve a detection rate of 86.7 % with a 0.85 % false-positive rate for online detection, and a 98.4 % detection rate with a 0.62 % false-positive rate for offline detection. To make up the flaws in Tor’s current blocking-resistance mechanism, we also provide some countermeasures from the perspective of Tor network and users, respectively.     

Understanding consumers’ continuance intention towards mobile advertising: a theoretical framework and empirical study

While issues regarding mobile advertising have captured the interest and attention of both practitioners and academics, in practice success stories are rare. An understanding of the continuance intention to use such services can provide insights into failed mobile marketing campaigns, and help to improve the implementation of future ones. Therefore, it is important to examine the underlying drivers of loyalty with regard to mobile advertising. This study uses the expectation–confirmation model in conjunction with the perspectives of value and trust to derive an integrated model to better understand the motivations behind consumers’ continued use of mobile advertising. We conducted an empirical study consisting of an online survey of 508 consumers who had experience with mobile advertising. The results show that perceived value, perceived usefulness, and satisfaction all directly influence continuance intention. Furthermore, consumer satisfaction has a crucial intervening role in the relationships that perceived value, perceived usefulness, and confirmation have with continuance intention. The theoretical and practical implications of the findings are discussed. One key limitation of this research is that the majority of respondents were students, although this group is the chief user of mobile advertising. Future research could be extended to consider other drivers of loyalty in this context, such as cultural differences and personal behavioural characteristics.     

A comparative review on mobile robot path planning: Classical or meta-heuristic methods?

The involvement of Meta-heuristic algorithms in robot motion planning has attracted the attention of researchers in the robotics community due to the simplicity of the approaches and their effectiveness in the coordination of the agents. This study explores the implementation of many meta-heuristic algorithms, e.g. Genetic Algorithm (GA), Differential Evolution (DE), Particle Swarm Optimization (PSO) and Cuckoo Search Algorithm (CSA) in multiple motion planning scenarios. The study provides comparison between multiple meta-heuristic approaches against a set of well-known conventional motion planning and navigation techniques such as Dijkstra’s Algorithm (DA), Probabilistic Road Map (PRM), Rapidly Random Tree (RRT) and Potential Field (PF). Two experimental environments with difficult to manipulate layouts are used to examine the feasibility of the methods listed. several performance measures such as total travel time, number of collisions, travel distances, energy consumption and displacement errors are considered for assessing feasibility of the motion planning algorithms considered in the study. The results show the competitiveness of meta-heuristic approaches against conventional methods. Dijkstra ’s Algorithm (DA) is considered a benchmark solution and Constricted Particle Swarm Optimization (CPSO) is found performing better than other meta-heuristic approaches in unknown environments.     

Effects of the design of mobile security notifications and mobile app usability on users’ security perceptions and continued use intention

The explosive global adoption of mobile applications (i.e., apps) has been fraught with security and privacy issues. App users typically have a poor understanding of information security; worse, they routinely ignore security notifications designed to increase security on apps. By considering both mobile app interface usability and mobile security notification (MSN) design, we investigate how security perceptions of apps are formed and how these perceptions influence users’ intentions to continue using apps. Accordingly, we designed and conducted a set of controlled survey experiments with 317 participants in different MSN interface scenarios by manipulating the types of MSN interfaces (i.e., high vs. low disruption), the context (hedonic vs. utilitarian scenarios), and the degree of MSN intrusiveness (high vs. low intrusiveness). We found that both app interface usability and the design of MSNs significantly impacted users’ perceived security, which, in turn, has a positive influence on users’ intention to continue using the app. In addition, we identified an important conundrum: disruptive MSNs—a common approach to delivering MSNs—irritate users and negatively influence their perceptions of app security. Thus, our results directly challenge current practice. If these results hold, current practice should shift away from MSNs that interrupt task performance.     

Of ‘knowing science’ and of ‘doing science’: A reaffirmation of the tacit and the affective in science and science education

Abstract:

Most of school science concentrates on helping students gain a knowledge and understanding of explicit science, which may subsequently be tested in examinations. It presents a picture of science as a secure body of knowledge, gained by scientists working according to the standard procedures of science. In this paper I stress a different model of science: the looseness of the knowledge held, the idiosyncratic methods by which it is obtained, and the personal way in which it is used to solve problems. I also stress the importance of tacit knowledge and the affective driving force, which describe the personal knowledge that scientists both hold and utilize; I analyse the nature of authentic science in terms of the type of knowledge that scientists know and the way in which scientists work. The arguments for and against such authentic science in schools are considered, together with the factors limiting its practicality. Influenced by the writing of Polanyi, Hodgkin, and Claxton and by experience of, and researches into, students doing problem‐solving projects in schools, I argue that it is desirable, and possible, to incorporate some such authentic science into the school science curriculum. In spite of many unsympathetic pressures acting on current schooling, I believe that there is a vital need to reaffirm the importance of the tacit and the affective in school science.     

Are mobile phone conversations always so annoying? The ‘need-to-listen’ effect re-visited

According to Monk et al. (2004a Monk, A.F., et al., 2004a. Why are mobile phones annoying? Behaviour & Information Technology, 23 (1), 33–42. doi: 10.1080/01449290310001638496[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]. Why are mobile phones annoying? Behaviour and Information Technology, 23 (1), 33–42), mobile phone conversations are annoying to overhear due to an involuntary need-to-listen in order to predict the inaudible half of the conversation. However, previous support for this need-to-listen explanation of annoyance has failed to consider the confound that mobile phone conversations also have less predictable acoustic patterns and has only investigated ‘neutral’ conversations. By staging mobile and face-to-face conversations in public, this study further supports the need-to-listen explanation. By removing the need-to-listen to the content of a mobile conversation through introducing foreign speech, bystanders no longer perceived the conversation as more annoying than a conversation between two co-present individuals, supporting the need-to-listen explanation over unpredictable acoustics. In two further experiments manipulating conversational content (‘neutral’ vs. ‘intriguing’), findings suggest that the need-to-listen to mobile phone conversations is not inherently annoying; it can be annoying or possibly even ‘interesting’ depending on the conversational content.     

Bilateral Trade and ‘Small-World’ Networks

Trade requires search, negotiation, and exchange, which are activities thatabsorb resources. Thispaper investigates how different trade networks attend to these activities.An artificial marketis constructed in which autonomous agents endowed with a stock of goods seekout partners,negotiate a price, and then trade with the agent offering the best deal.Different trade networksare imposed on the system by restricting the set of individuals with whom anagent cancommunicate. We then compare the path to the eventual equilibrium as well asthe equilibriumcharacteristics of each trade network to see how each system dealt with thetasks of search,negotiation, and exchange.Initially, all agents are free to trade with any individual in the globalmarket. In such a world,global resources are optimally allocated with few trades, but only after atremendous amount ofsearch and negotiation. If trade is restricted within disjoint localboundaries, search is simple butglobal efficiency elusive. However, a hybrid model in which most agents tradelocally but a fewagents trade globally results in an economy that quickly reaches a Paretooptimal equilibriumwith significantly lower search and negotiation costs. Such small-worldnetworks occur innature and may help explain the ease with which most of us acquire goods fromaround theworld. We also show that there are private incentives for such a system toarise.     

Smart Workplaces for older adults: coping ‘ethically’ with technology pervasiveness

Universal Access in the Information Society - Pervasive technologies such as Artificial Intelligence, Virtual Reality and the Internet of Things, despite their great potential for improved...     

Leveraging Microsoft׳s mobile usability guidelines: Conceptualizing and developing scales for mobile application usability

This research conceptualizes mobile application usability and develops and validates an instrument to measure the same. Mobile application usability has attracted widespread attention in the field of human–computer interaction because well-designed applications can enhance user experiences. To conceptualize mobile application usability, we analyzed Microsoft’s mobile usability guidelines and defined 10 constructs representing mobile application usability. Next, we conducted a pilot study followed by a quantitative assessment of the content validity of the scales. We then sequentially applied exploratory factor analysis and confirmatory factor analysis to two samples (n=404; n=501) consisting of German consumers using mobile social media applications on their smartphones. To evaluate the confirmatory factor model, we followed a step-by-step process assessing unidimensionality, discriminant validity and reliability. To assess the nomological validity of our instrument, we examined the impact of mobile application usability on two outcomes: continued intention to use and brand loyalty. The results confirmed that mobile application usability was a good predictor of both outcomes. The constructs and scales associated with mobile application usability validated in this paper can be used to guide future research in human–computer interaction and aid in the effective design of mobile applications.     

Spreadsheet development and ‘what-if’ analysis: quantitative versus qualitative errors

Past research has shown that errors are relatively common in all types of spreadsheets. As spreadsheets are used widely by executives in analyzing and supporting their decision making, especially in financial analysis, budgeting and forecasting applications, it is important for spreadsheets to be accurate. Errors undetected in spreadsheets may have undesirable consequences. For example, errors may adversely impact the firm's competitiveness or profitability when the costing of projects is prone to incorrect computation. For this purpose, we investigate the types of errors that may occur even for simple domain-free spreadsheet problems. In addition, we also show that spreadsheet errors are difficult to detect during ‘what-if’ analysis (i.e. when some design parameters are changed) when spreadsheets are not properly designed. The results show that most students do not take due care in designing spreadsheets. It appears that the techniques in teaching spreadsheets should really focus on how to design a comprehensive spreadsheet that is both easy to maintain and debug rather than just demonstrating the many features of spreadsheets.     

Parallel block pc methods with rkn-type correctors and adams-type predictors ∗

This paper describes the construction of block predictor - corrector methods based on Runge-Kutta-Nyström correctors. Our approach is to apply the predictor - corrector method not only at step point, but also at off-step points (block points), so that in each step, a whole block of approximations to the exact solution at off-step points is computed. In the next step, these approximations are used to obtain a high-accurate predictions using Adams-type formulas. By suitable choice of the abscissas of the off-step points, a much more accurately predicted value is obtained than by predictions using last step values. Since the block of approximations at the off-step points can be computed in parallel, the sequential costs of these block predictor - corrector methods are comparable with those of a conventional predictor - corrector method. Furthermore, by using Runge-Kutta-Nyström corrector methods, the computation of the approximation at each off-step point is also highly parallel. Application of the resulting block predictor -corrector methods to a few widely-used test problems reveals that the sequential costs are very much reduced when compared with the best parallel and sequential methods from the literature.     

Vulnerability,Resilience and ‘Systemic Interest’: a Connectivity Approach

Networks and Spatial Economics - This paper analyzes the socio-economic dimension of vulnerability and resilience from the viewpoint of connectivity. While no consensus has yet emerged on...