Resource Searching is one of the key functional tasks in large complex networks. With the P2P architecture, millions of peers connect together instantly building a communication pattern. Searching in mobile networks faces additional limitations and challenges. Flooding technique can cope up with the churn and searches aggressively by visiting almost all the nodes. But it exponentially increases the network traffic and thus does not scale well. Further the duplicated query messages consume extra battery power and network bandwidth. The blind flooding also suffers from long delay problem in P2P networks. In this paper, we propose optimal density based flooding resource discovery schemes. Our first model takes into account local graph topology information to supplement the resource discovery process while in our extended version we also consider the neighboring node topology information along with the local node information to further effectively use the mobile and network resources. Our proposed method reduces collision at the same time minimizes effect of redundant messages and failures. Overall the methods reduce network overhead, battery power consumption, query delay, routing load, MAC load and bandwidth usage while also achieving good success rate in comparison to the other techniques. We also perform a comprehensive analysis of the resource discovery schemes to verify the impact of varying node speed and different network conditions.
The Internet of Things (IoT) revolutionised the way devices, and human beings, cooperate and interact. The interconnectivity and mobility brought by IoT devices led to extremely variable networks, as well as unpredictable information flows. In turn, security proved to be a serious issue for the IoT, far more serious than it has been in the past for other technologies. We claim that IoT devices need detailed descriptions of their behaviour to achieve secure default configurations, sufficient security configurability, and self-configurability. In this article, we propose S×C4IoT, a framework that addresses these issues by combining two paradigms: Security by Contract (S×C) and Fog computing. First, we summarise the necessary background such as the basic S×C definitions. Then, we describe how devices interact within S×C4IoT and how our framework manages the dynamic evolution that naturally result from IoT devices life-cycles. Furthermore, we show that S×C4IoT can allow legacy S×C-noncompliant devices to participate with an S×C network, we illustrate two different integration approaches, and we show how they fit into S×C4IoT. Last, we implement the framework as a proof-of-concept. We show the feasibility of S×C4IoT and we run different experiments to evaluate its impact in terms of communication and storage space overhead.
The Internet of Things (IoT) is captivating the society because of its potential to rapidly transform businesses and people’s lives. It is widely believed that IoT will also transform the industrial automation business in terms of improved productivity, less cost, flexibility, and increased revenues. Hence, there are some challenges that needs to be addressed when IoT is introduced to the industrial automation domain. This paperaims to present realistic requirements and highlights identified challenges such as security, interoperability, deterministic and low latency communication, and how the required availability (uptime) can be kept. Moreover, the paper also point out the need of standardization and sustainable business models. The conclusion is that introducing IoT devices and connecting them directly to cloud services is not straightforward for process automation.
Websites are today the face of an organization, with Global reach. The Information and Technology (IT) Act 2000 of India, is entirely silent on the subject of web accessibility. However the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) guidelines of 2009, which has been ratified by Govt. of India, of which Article 9.2 (g) & (h) especially lays down that, states should facilitate access for Persons with disabilities (PWDs) to new information and communication technologies, especially the Internet. A study was undertaken on 3rd December 2009, to analyze the qualities of a website designed by Government Organizations (GOs) and Non-Government Organizations (NGOs) working for PWDs in terms of Information & Dissemination, Accessibility, Design and Interactive participatory features. The main contribution of this study is to illuminate the features of websites used by GOs and NGOs working for PWDs in India and its accessibility.
Mathematical creativity is increasingly important for improved innovation and problem-solving. In this paper, we address the question of how to best investigate mathematical creativity and critically discuss dichotomous creativity scoring schemes. In order to gain deeper insights into creative problem-solving processes, we suggest the use of mobile, unobtrusive eye-trackers for evaluating students’ creativity in the context of Multiple Solution Tasks (MSTs). We present first results with inexpensive eye-tracking goggles that reveal the added value of evaluating students’ eye movements when investigating mathematical creativity—compared to an analysis of written/drawn solutions as well as compared to an analysis of simple videos.
PIM is an acronym for Passive InterModulation, an interference problem in wireless systems. The problem is not new, but has been known since long time back by designers of, for instance cell phone systems, space probes, connectors, coaxial cables, antennas and filters. The problem most frequently occurs, when dealing with high RF-currents in confined spaces. In this text, the basic theories behind PIM will be briefly discussed.
A method af assigning transmitting power and frequency to narrow band links exposed to nonselective fading and self induced interference in an HF radio data network is suggested. The method uses vector optimization by means of a feedforward neural network.The network performance measure used is a weighted sum of mutual information for all links in the network. The suggested assignment method can be used for power and frequency planning using simulated fading and interference data. It can also be used with actual measured link data in an adaptive on-line system. The method is capable of handling links utilizing frequency diversity and can also take LPD/LPI aspects into account. Simulation results indicate that the degree of correlation in space and frequency between different links palys ab important role in the assignment process.
A frequency hopping scheme (1 bit per chip) is proposed and studied in som detail for channels in the HF-band. This band is subject to interference that varies with time and frequency, due to varying transmission and propagation conditions. To make efficient use of the available channel resource an adaptive frequency hopping algorithm has been implemented by means of a neural network to make use of the available channel information from the link quality analysis (LQA) in selecting the frequency slot in contrast to having a uniformly distributed selection process. The algorithm proposed combines the advantages of low probability of detection during transmission and reduced fading and interference disturbances when detecting transmitted signals. The disturbances not eliminated by the channel selection is further reduced by using block codes with first order soft decision decoding. The results on residual bit error rate and average signal to interference ratio are promising with an overall reduction of bit error rate of more than two ordes of magnitude at moderate signal to noise and signal to interference ratios for a course channel model based upon the results by Laycook et al.