Massive data delivery in unstructured peer-to-peer networks with network coding

With more and more multimedia applications on the Internet, such as IPTV, bandwidth becomes a vital bottleneck for the booming of large scale Internet based multimedia applications. Network coding is recently proposed to take advantage to use network bandwidth efficiently. In this paper, we focus on massive multimedia data, e.g. IPTV programs, transportation in peer-to-peer networks with network coding. By through study of networking coding, we pointed out that the prerequisites of bandwidth saving of network coding are: 1) one information source with a number of concurrent receivers, or 2) information pieces cached at intermediate nodes. We further proof that network coding can not gain bandwidth saving at immediate connections to a receiver end; As a result, we propose a novel model for IPTV data transportation in unstructured peer-to-peer networks with network coding. Our preliminary simulations show that the proposed architecture works very well.

An efficient and distributed file search in unstructured peer-to-peer networks

Peer-to-peer (P2P) networks are gaining increased attention from both the scientific community and the larger Internet user community. Data retrieval algorithms lie at the center of P2P networks, and this paper addresses the problem of efficiently searching for files in unstructured P2P systems. We propose an Improved Adaptive Probabilistic Search (IAPS) algorithm that is fully distributed and bandwidth efficient. IAPS uses ant-colony optimization and takes file types into consideration in order to search for file container nodes with a high probability of success. We have performed extensive simulations to study the performance of IAPS, and we compare it with the Random Walk and Adaptive Probabilistic Search algorithms. Our experimental results show that IAPS achieves high success rates, high response rates, and significant message reduction.

Experiences in developing a micro-payment system for peer-to-peer networks

Micro-payment systems are an important part of peer-to-peer (P2P) networks and address the "free-rider" problem in most existing content sharing systems. To address this issue, the authors have developed a new micro-payment system for content sharing in P2P networks called P2P-Netpay. This is an offline, debit based protocol that provides a secure, flexible, usable and reliable credit service. This article compares micro-payment with non-micro-payment credit systems for file sharing applications and finds that this approach liberates the "free-rider" problem. The authors analyse the heuristic evaluation performed by a set of evaluators and present directions for research aiming to improve the overall satisfaction and efficiency of the proposed model.

Improving prediction interval quality : a genetic algorithm-based method applied to neural networks

The delta technique has been proposed in literature for constructing
prediction intervals for targets estimated by neural networks. Quality of constructed prediction intervals using this technique highly depends on neural network characteristics. Unfortunately, literature is void of information about how these dependences can be managed in order to optimize prediction intervals. This study attempts to optimize length and coverage probability of prediction intervals through modifying structure and parameters of the underlying neural networks. In an evolutionary optimization, genetic algorithm is applied for finding the optimal values of network size and training hyper-parameters. The applicability and efficiency of the proposed optimization technique is examined and demonstrated using a real case study. It is shown that application of the proposed optimization technique significantly improves quality of constructed prediction intervals in term of length and coverage probability.

A control methodology for DFIG type wind turbines connected to distribution networks

This paper proposes a decentralised controller design for doubly-fed induction generators (DFIGs) to enhance dynamic performance of distribution networks. The change in the output power due to the variable nature of wind is considered as an uncertain term in the design algorithm. In addition, the interconnection effect of the other subsystems are considered in the design process. The H norm of the uncertain system is found out and simultaneous output-feedback linear controllers are designed based controller is verified on a 16 bus distribution test system for severe disturbances. Simulation results indicate that the designed controller is robust against uncertainties in operating conditions

Fog computing: a cloud to the ground support for smart things and machine-to-machine networks

Cloud services to smart things face latency and intermittent connectivity issues. Fog devices are positioned between cloud and smart devices. Their high speed Internet connection to the cloud, and physical proximity to users, enable real time applications and location based services, and mobility support. Cisco promoted fog computing concept in the areas of smart grid, connected vehicles and wireless sensor and actuator networks. This survey article expands this concept to the decentralized smart building control, recognizes cloudlets as special case of fog computing, and relates it to the software defined networks (SDN) scenarios. Our literature review identifies a handful number of articles. Cooperative data scheduling and adaptive traffic light problems in SDN based vehicular networks, and demand response management in macro station and micro-grid based smart grids are discussed. Security, privacy and trust issues, control information overhead and network control policies do not seem to be studied so far within the fog computing concept.

An efficient MAC protocol with adaptive energy harvesting for machine-to-machine networks

In a machine-to-machine network, the throughput performance plays a very important role. Recently, an attractive energy harvesting technology has shown great potential to the improvement of the network throughput, as it can provide consistent energy for wireless devices to transmit data. Motivated by that, an efficient energy harvesting-based medium access control (MAC) protocol is designed in this paper. In this protocol, different devices first harvest energy adaptively and then contend the transmission opportunities with energy level related priorities. Then, a new model is proposed to obtain the optimal throughput of the network, together with the corresponding hybrid differential evolution algorithm, where the involved variables are energy-harvesting time, contending time, and contending probability. Analytical and simulation results show that the network based on the proposed MAC protocol has greater throughput than that of the traditional methods. In addition, as expected, our scheme has less transmission delay, further enhancing its superiority.

Case study of e-learning experts in Malaysia : impact of social capital and social networks

This paper examines the experiences of selected academics pioneering e-learning in Malaysian tertiary institutions. It begins with an overview of the broad factors shaping the Malaysian educational environment and then proceeds to examine the experience of individual teachers and e-learning programs. It takes an in-depth qualitative approach to engaging with this case study material drawing heavily on semi-structured interviews with key actors.
Conversations with several respondents suggested that the social networks of mentor relations found in the Malaysian case studies might be aptly described as ‘bamboo networks’. Bamboo, which happens to be plentiful in the Malaysian peninsula where these case studies are based, spreads from clump to clump through a series of underground connections involving a mature clump of bamboo sending out a subterranean runner, often over very long distances that then emerge into the open as a new bamboo clump.
All of those interviewed reported that they have found it difficult to find a support base in their first years of pioneering online developments. Consequently, they tended to fall back on their peer networks linked to the institutions at which they had studied. Prominent individuals championing e-learning in the institutions where they teach tend to form small groups for information sharing and networking. They do look to their management for tacit ‘permission’ rather than direct encouragement. Consequently, the active promotion of e-learning in Malaysia can be described as being ‘middle-down’ rather than ‘top-down’ in nature. That is to say, it is mid-level teachers that inspire those below them to join in the development of e-learning programs. They are internally driven and strongly motivated. In time, their activity should produce new generations of locally developed e-learning experts but this has yet to take place in a substantial fashion. This study shows that both men and women ‘academic guanxi’, or peer networks, play a key role in the adoption of online technologies. Key early adopters become change-agents by inspiring a small network of their peers and via their guanxi networks. It was also discovered that motivation is not simply an individual matter but is also about groups and peer networks or communities of exchange and encouragement. In the development of e-learning in Malaysia, there is very little activity that is not linked to small clusters of developers who are tied into wider networks through personal contacts.
Like clumping bamboo, whilst the local clusters tend to be easily seen, the longer-range ‘subterranean’ personal connections are generally not nearly so immediately obvious. These connections are often the product of previous mentoring relationships, including the relationships between influential teachers and their former postgraduate students. These relationships tend to work like bamboo runners: they run off in multiple directions, subterranean and unseen and then throw up new clumps that then send out fresh runners of their own.

An authentication framework for e-health systems

The high-level sensitivity of medical information mandates stronger authentication and authorization mechanisms to be used in e-Health systems. This paper describes the design and implementation of certificate-based e-Health authentication and authorization architecture. This architecture was developed to authenticate e-Health professionals accessing shared clinical data among a set of affiliated health institutions based on peer-to- peer networks. The architecture had to accommodate specific medical data sharing and handling requirements, namely the security of professionals' credentials.

A transformation model for heterogeneous servers

One of the characteristics of the current Web services is that many clients request the same or similar service from a group of replicated servers, e.g. music or movie downloading in peer-to-peer networks. Most of the time, servers are heterogeneous ones in terms of service rate. Much of research has been done in the homogeneous environment. However, there is has been little done on the heterogeneous scenario. It is important and urgent that we have models for heterogeneous server groups for the current Internet applications design and analysis. In this paper, we deploy an approximation method to transform heterogeneous systems into a group of homogeneous system. As a result, the previous results of homogeneous studies can be applied in heterogeneous cases. In order to test the approximation ratio of the proposed model to real applications, we conducted simulations to obtain the degree of similarity. We use two common strategies: random selection algorithm and Firs-Come-First-Serve (FCFS) algorithm to test the approximation ratio of the proposed model. The simulations indicate that the approximation model works well.

Cultural factors behind the growth of e-learning in Malaysia Academic guanxi

This paper aims to discover and examine ways in which cultural factors shape the adoption and use of information technology for online teaching. This research focuses on influential early adopters in the tertiary education sector in Malaysia who have become change-agents by inspiring small networks of their peers. The study examines the concept of guanxi to understand the operation of trust and inspiration in networking and teamwork in the Asian academic environment. This study points to the importance of developing guanxi, through the middle-down nurturing of peer networks, in developing a rich and rewarding environment for the development of online teaching.

Community pharmacists' preferences for continuing education delivery in Australia

Introduction: New technologies such as the Internet offer an increasing number of options for the delivery of continuing education (CE) to community pharmacists. Many of these options are being utilized to overcome access- and cost-related problems. This paper identifies learning preferences of Australian community pharmacists for CE and identifies issues with the integration of these into contemporary models of CE delivery.
Methods: Four focus group teleconferences were conducted with practicing community pharmacists (n = 15) using a semistructured format and asking generally about their CE and continuing professional development (CPD) experiences.
Results: Pharmacists reported preferences for CE that were very closely aligned to the principles of adult learning. There was a strong preference for interactive and multidisciplinary CE. Engaging in CPD was seen as valuable in promoting reflective learning.
Discussion: These results suggest that pharmacists have a strong preference for CE that is based on adult learning principles. Professional organizations should take note of this and ensure that new CE formats do not compromise the ability of pharmacists to engage in interactive, multidisciplinary, and problem-based CE. Equally, the role of attendance-based CE in maintaining peer networks should not be overlooked.

Gender differences in the impact of families on alcohol use : a lagged longitudinal study of early adolescents

Aims From the pre-teen to the mid-teen years, rates of alcohol use and misuse increase rapidly. Cross-sectional research shows that positive family emotional climate (low conflict, high closeness) is protective, and there is emerging evidence that these protective mechanisms are different for girls versus boys. The aim of this study was to explore gender differences in the longitudinal impact of family emotional climate on adolescent alcohol use and exposure to peer drinking networks.

Design Three-wave two-level (individual, within-individual over time) ordinal logistic regression with alcohol use in the past year as the dependent measure and family variables lagged by 1 year.

Setting Adolescents completed surveys during school hours.

Participants A total of 855 Australian students (modal age 10–11 years at baseline) participating in the International Youth Development Study (Victoria, Australia).

Measurements These included emotional closeness to mother/father, family conflict, parent disapproval of alcohol use and peer alcohol use.

Findings For girls, the effect of emotional closeness to mothers on alcohol use was mediated by exposure to high-risk peer networks. Parent disapproval of alcohol use was protective for both genders, but this effect was larger for boys versus girls, and there was no evidence that peer use mediated this effect. Peer drinking networks showed stronger direct risk effects than family variables.

Conclusions Family factors unidirectionally impact on growth in adolescent alcohol use and effects vary with child gender.