Search results

This paper aims to determine the network efficient topology for low power and lossy networks (LLNs) using routing protocol for LLN (RPL) with respect to the increase in network size and propose a novel approach to overcome the shortcomings of the existing models.

The authors have used Contiki OS/Cooja simulator to conduct experiments on primarily four topologies (star, bus/linear, ring/eclipse and random). They have implemented RPL protocol using Sky motes for each topology from 10, 20, 30 and up to 70 nodes. Consequently, after 24 h of experimentation, the readings have been noted and, alongside, a comprehensive comparative analysis has been performed based on the network density and metric parameters: packet delivery ratio (PDR), expected transmission (ETX) and power consumption. Further, a hybrid model is proposed where the additional factors of mobility, multiple sink and a combination of static and mobile nodes are introduced. The proposed model is then compared with the star model (all static nodes and star topology) and the dynamic model (all mobile nodes) to analyze the efficiency and network performance for different network sizes (28, 36, 38 and 44 nodes). The mobility is introduced using BonnMotion tool in Contiki OS.

Simulation results have shown that the star topology is most network efficient when compared with bus/linear, ring/eclipse and random topologies for low density and high scalable network. But when the same setup is compared with the proposed hybrid model, the proposed model shows a significant improvement and gives the best and efficient network performance with highest PDR (average improvement approximately 44.5%) and lowest ETX (average improvement approximately 49.5%) comparatively.

Also, these findings will benefit the deployment of smart devices used in advanced metering infrastructure, road side units and in various industrial applications such as traffic monitoring system, electronic toll collection and traffic analysis in the smart grid infrastructure.

The impact of topology is significant and detailed analysis is required to understand the impact of different topologies of the nodes in the network for the present and the future scenarios. As very few research studies have discussed this gap, this research paper is quintessential and shall open novel future potential direction. Also, the proposed approach of hybrid model with mobility has not been considered in the literature yet.

This paper aims to obtain a symmetrical step-down topology with lower equivalent capacity and wider step-down range under the condition of the same output. Two new symmetrical step-down topologies of star-connected autotransformers are proposed in this paper. Taking the equivalent capacity as the main parameter, the obtained topologies are modeled and analyzed in detail.

This paper adopts the research methods of design, modeling, analysis and simulation verification. First, the star-connected autotransformer is redesigned according to the design objective of symmetrical step-down topology. In addition, the mathematical model of two topologies is established and a detailed theoretical analysis is carried out. Finally, the theoretical results are verified by simulation.

Two symmetrical star-connected autotransformer step-down topologies are designed, the winding configurations of the corresponding topology are presented, the step-down ranges of these three topologies are calculated and the influence of step-down ratio on the equivalent capacity of autotransformer are analyzed. Through analysis, the target step-down topologies are obtained when the step-down ratio is [1.1, 5.4] and [1.1, 1.9] respectively.

Because the selected research object is only a star-connected autotransformer, the research results may lack generality. Therefore, researchers are encouraged to further study the topologies of other autotransformers.

This paper includes the implications of the step-down ratio on the equivalent capacity of autotransformers and the configuration of transformer windings.

The topologies designed in this paper enable star-connected autotransformer in the 12-pulse rectifier to be applied in step-down circumstances rather than situations of harmonic reduction only. At the same time, this paper provides a way that can be used to redesign the autotransformer in other multi-pulse rectifier systems, so that those transformers can be used in voltage regulation.

To utilize Bluetooth as a layer 2 multi‐hop subnet for global IP network, there are two missing protocols in current Bluetooth stack: network formation and routing. In this paper, we propose our network formation and routing protocols optimized for such Bluetooth subnset usage scenarios to fill this gap. In this paper, we first present some observations on performance degradations of Bluetooth PAN due to network topologies and topology change when radio independant protocols are implemented. And then we analyze the reason of performance degradation. Based on our analysis, we first propose a flexible scatternet formation algorithm under conference scenario for multi‐hop communication. By using proposed method, scatternet can be formed flexibly with star, mesh, or linked line based on several parameters like number of maximum piconets that a gateway Bluetooth device can participate, and whether loops are needed in the resulting scatternet to achieve better network performance. To utilize topology information in multi‐hop communication, we propose a Cross‐layer Optimized Routing for Bluetooth (CORB) CORB is a QoS‐extended AODV routing protocol with mainly two optimizations between networking layer and underlying Bluetooth MAC layer. The first optimization is to use a new load metric. (LM) in QoS routing protocol instead of number of hops in conventional best effort routing. LM is derived from estimation of nodes’ link bandwidth, which reflects the different roles of nodes in Bluetooth scatternet. This proposal helps routing protocol to bypass heavily loaded nodes, and find route with larger bandwidth. The second optimization is to adjust LM and some MAC layer parameters in response to the unstable network topology caused by movement and change of indoor radio condition. Finally, We present some simulation and experiment results based on implementation, which prove the effectiveness of our protocols.

The purpose of this paper is to find the reliability measures of Linux operating system connected in local area network (LAN).

The system has two different topologies, i.e. star topology (subsystem-1) and bus topology (subsystem-2), are placed at two different places, and connected to a server through a hub. Both the topologies have n clients. The system has partial failure and complete failure. The partial failure is of two type’s namely minor partial and major partial. The minor partial failure degrades the system whereas the major partial failure brings the system to a break down mode. The system can completely fail due to failure of server hacking and blocking.

By using supplementary variable technique and Laplace transformation, by taking different types of failure and two types of repairs the availability, non-availability, mean time to failure and cost analysis (expected profit) of the design system have been obtained.

In this research, a mathematical model of Linux operating system has been discussed from which one can check the behavioral analysis of the designed system.

A variety of phenomena such as world wide web, social or business networks, interactions are modelled by various kinds of networks (such as the scale free or preferential attachment networks). However, due to the model‐specific requirements one may want to rewire the network to optimize the communication among the various nodes while not overloading the number of channels (i.e. preserving the number of edges). The purpose of this paper is to present a formal framework for this problem and to examine a family of local search strategies to cope with it.

This is mostly theoretical work. The authors use rigorous mathematical framework to set‐up the model and then we prove some interesting theorems about it which pertain to various local search algorithms that work by rerouting the network.

This paper proves that in cases when every pair of nodes is sampled with non‐zero probability then the algorithm is ergodic in the sense that it samples every possible network on the specified set of nodes and having a specified number of edges with nonzero probability. Incidentally, the ergodicity result led to the construction of a class of algorithms for sampling graphs with a specified number of edges over a specified set of nodes uniformly at random and opened some other challenging and important questions for future considerations.

The measure‐theoretic framework presented in the current paper is original and rather general. It allows one to obtain new points of view on the problem.

This paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The computed results are more supportable for repairable system performability analysis.

In this paper, the authors have analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The supplementary variable technique has employed for analyzing the performance of the system.

Reliability measures have been computed for different types of configuration. It generalized the results for purely series and purely parallel configurations.

This research may be beneficial for industrial system performances whereas a k-out-of-n-type configuration exists.

Not sure as it is a theoretical assessment.

This research may not have social implications.

This work is the sole work of authors that have not been communicated to any other journal before.

Proper function of landing gear plays a crucial role in the safe operation of an airplane. Traditional landing gear control system utilizes centralized control technology. The relatively heavy wire harness and low reliability accompanied with this technology make it logical to transfer from traditional control to real‐time distributed control. This paper aims to look into a new landing gear control system based on time‐triggered architecture (TTA).

In this paper, a new landing gear control system based on TTA is proposed. The reliability of the proposed system is investigated using a combination of Markov analysis and MIL‐HDBK‐217 methods.

The results show that by integration of TTP/C and TTP/A technologies, the advantages of both are achieved. A very high level of reliability is obtained. This increases the confidence when adopting distributed landing gear control technology.

The paper presents a new landing gear control system based on TTA, the reliability of which is very high.

A local area network (LAN) connects computers, printers, modems and other devices located near each other, often in an office environment. The School of Library and Information Science (SLIS) at the University of Wisconsin‐Milwaukee provides a case study of selecting and using a LAN in an academic program environment. Consideration of various types of LANs took place during the selection of a LAN for SLIS. The advantages of having a LAN at SLIS have been the sharing of printers and other devices, the use of electronic mail, improvement in office management and cooperative research, and easier access to information and files available in the school.

A primary task of wireless sensor networks is to measure environmental conditions. In most applications, a sink node is responsible for collecting data from the sensors through multihop communications. The communication pattern is called convergecast. However, radio congestion around the sink can easily become a bottleneck for the convergecast. The purpose of this paper is to consider both scheduling algorithms and routing structures to improve the throughput of convergecast.

The paper addresses the issue from two perspectives. First by considering the transition scheduling that reduces radio interference to perform convergecast efficiently. Second, by studying the effects of routing structures on convergecast. A routing algorithm, called disjoint‐strip routing, is proposed as an alternative to existing shortest‐path routing.

The paper shows that constructing a shortest‐length conflict‐free schedule is equivalent to finding a minimal vertex coloring. To solve the scheduling problem, a virtual‐node expansion is proposed to handle relay operations and then coloring algorithms are utilized. Regarding the routing structures, a disjoint‐strip algorithm is proposed to leverage possible parallel transmissions. Proposed algorithms are evaluated through simulations.

This paper separates the problem for optimizing data‐collection throughput into two stages: constructing a routing structure on a given deployment; and scheduling the activation time of each link. Determining routing topologies and communication schedules for optimal throughput are shown to be hard, so heuristics are applied in both stages. VNE is proposed, which makes traffic information visible to coloring algorithms. The advantage of VNE is verified through simulations. VNE can be applied to any coloring algorithm and any deterministic traffic pattern. It is shown that routing structures set a limit on the performance of scheduling algorithms. There are two possible ways in routing algorithms to improve convergecast throughput: first, by reducing the total number of transmissions during data collection; second, by transferring data in parallel. The shortest‐path routing addresses the first point while DS addresses the second one. As expected, when the deployments are even and balanced, minimizing the number of transmissions is more effective than parallelizing them. On the other hand, when the deployments are unbalanced and conflicts are not strict, parallel transmissions can improve the throughput.