Internet infrastructure security: a taxonomy

The pervasive and ubiquitous nature of the Internet coupled with growing concerns about cyber terrorism demand immediate solutions for securing the Internet infrastructure. So far, the research in Internet security primarily focused on. securing the information rather than securing the infrastructure itself. Given the prevailing threat situation, there is a compelling need to develop architectures, algorithms, and protocols to realize a dependable Internet infrastructure. In order to achieve this goal, the first and foremost step is to develop a comprehensive understanding of the security threats and existing solutions. This article attempts to fulfill this important step by providing a taxonomy of security attacks, which are classified into four main categories: DNS hacking, routing table poisoning, packet mistreatment, and denial-of-service attacks. The article discusses the existing solutions for each of these categories, and also outlines a methodology for developing secure protocols.     

Effect of structural evolution and surface morphological changes on the electrochemical response of an FeNbAlMnCuSiB alloy

The electrochemical response of a soft magnetic FeNbAlMnCuSiB alloy was studied through different stages of devitrification. The structural evolution including appearance of a nanocrystalline phase and intermetallics, and accompanying surface topographical changes were studied and correlated to the electrochemical behavior of this alloy. The electrochemical behavior was not directly related to changes in surface roughness but it was very responsive to the structural changes, particularly to the formation of the nanocrystalline phase and to the precipitation of Fe₇Nb₆ phase. There was a progressive passivation breakdown with the appearance of crystalline phases on annealing.     

Preferred link based delay-constrained least-cost routing in wide area networks

Multimedia applications involving digital audio and/or digital video transmissions require strict QoS constraints (end-to-end delay bound, bandwidth availability, packet loss rate, etc.) to be met by the network. To guarantee the real-time delivery of packets satisfying these constraints, a real-time channel (D. Ferrari and D.C. Verma, A scheme for real-time channel establishment in wide-area networks. IEEE JSAC, 8(3), 368–379, 1990) needs to be established before the transmission of packets of a connection can begin. The establishment of such channels requires the development of efficient route selection algorithms that are designed to take into account the QoS constraints.

The general problem of determining a least-cost delay-constrained route in a given communication network has been proved to be NP-hard (M.R. Garey and D.S. Johnson, Computers and Intractability: a guide to the theory of NP-completeness, W.H. Freeman, 1979). In this paper, we describe a preferred link approach to distributed delay-constrained least-cost routing in order to establish real-time channels. The approach attempts to combine the benefits of probing and backtracking based algorithms (better adaptiveness and wider search) with the advantages of distance-vector type algorithms (lower setup time). The scheme is flexible in that a variety of heuristics can be employed to order the neighbouring links of any given node. Three heuristics are proposed and their performance is studied through simulation experiments. The simulation results indicate that the proposed heuristics provide better performance than other preferred neighbour methods, in terms of increased call acceptance rate and lower average route cost. The heuristics are also shown to adapt much better to dynamic variations in network and link characteristics.     

An efficient dynamic scheduling algorithm for multiprocessorreal-time systems

Many time-critical applications require predictable performance and tasks in these applications have deadlines to be met. In this paper, we propose an efficient algorithm for nonpreemptive scheduling of dynamically arriving real-time tasks (aperiodic tasks) in multiprocessor systems. A real-time task is characterized by its deadline, resource requirements, and worst case computation time on p processors, where p is the degree of parallelization of the task. We use this parallelism in tasks to meet their deadlines and, thus, obtain better schedulability compared to nonparallelizable task scheduling algorithms. To study the effectiveness of the proposed scheduling algorithm, we have conducted extensive simulation studies and compared its performance with the myopic scheduling algorithm. The simulation studies show that the schedulability of the proposed algorithm is always higher than that of the myopic algorithm for a wide variety of task parameters     

Solar energy performance analysis of basin-type solar still under the effect of vacuum pressure

ABSTRACT

This paper deals with a solar still for distilled water, using the heat of the sun to evaporate, cool and then collect the water. They are used in areas where drinking water is unavailable, so that clean water is obtained from dirty water or from plants by exposing them to sunlight; vacuum pressure is delivered to still-type solar. The reason for selecting vacuum pressure is that during the monsoon and cloudy days, solar intensity will not be high as it leads to evaporation at lower temperature saline water under the soar still. The basin area for the production of 5 litres per day of fresh water is determined as 1.44?m²and the solar still basin area of 1.44?m² and 21.5° tilt angle are designed. Solar energy be may used full to alternate in electrical power and to purify water in future. Finally, the performance was analysed for the solar still with a vacuum pressure at 0.6 bar. The outcome of the theoretical analysis shows that adoption of 0.6 bar pressure inside the solar still improves the average performance by 30%. In order to overcome this problem, vacuum could be applied for the better performance of the solar still during the low solar intensity periods.     

Progress of MWCNT,Al2O3, and CuO with water in enhancing the photovoltaic thermal system

Hybrid photovoltaic thermal system is an effective method to convert solar energy into electrical and thermal energy. However, its effectiveness is widely affected due to the high temperature of photovoltaic panel, and it can be minimized by employing nanofluids to the PV/T systems. In this research, the effect of various nanoparticles on the PV/T systems was studied experimentally. The nanofluids Al₂O₃, CuO, and multiwall carbon nanotube (MWCNT) were dispersed with water at different volume fractions of 0, 0.5, 1, 2.5, and 5 (vol%) using ultrasonication process. The effect of nanomaterials on viscosity and density was classified. All tests were carried out in an outdoor laboratory setup for calibrating the PV temperatures, thermal conductivity, electrical power, electrical efficiency, and overall efficiency. In addition, the energy analyses were also made to estimate the loss of heat owing to the nanofluids. Results show that use of the nanofluid increased the electric power and electrical efficiency of PV/T compared with water. Furthermore, MWCNT and CuO reduced the cell temperature by 19%. Consequently, the nanofluids MWCNT, Al₂O₃, and CuO produced the impressive values of 60%, 55%, and 52% increase in an average electrical efficiency than conventional PV. Particularly, the MWCNT produced superior results compared with other materials. It is evidently clear from the result that the introduction of the nanofluid increases the thermal efficiency without adding any extra energy to the system. Moreover, insertion of Al₂O₃, CuO, and MWCNT on PV/T system increases the exergy efficiency more than conventional PV module.     

Experimental investigation on heat transfer enhancement in a minichannel using CuO-water nanofluid

In this work, CuO-water nanofluid with an average size of nanoparticles (24?nm) and volume concentrations of 0.1% and 0.5% is used. For the computer microprocessor cooling, an aluminium minichannel of dimension (40?×?1?×?3) mm³ is fabricated instead of an aluminium heat sink and a cooling fan. It is shown that the dispersion of nanoparticles into the distilled water has produced a considerable enhancement of the cooling of the minichannel. Experiments were conducted for Reynolds number ranging from 25 to 800 under a laminar regime. From the experiments, it is found that better heat transfer is achieved when CuO-water nanofluid is used as the working fluid.