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Cluster-based Communications System for Immediate Post-disaster Scenario  [cached]
Sonia Majid,Kazi Ahmed
Journal of Communications , 2009, DOI: 10.4304/jcm.4.5.307-319
Abstract: Communication facilities can totally be destroyed by natural and / or manmade disasters. A critical problem after disaster is getting the first hand knowledge of the destructions and also establishing some communication links among the survivors. This paper focuses on the vital need for providing communications facility to the victims, immediately after the disaster and prior to the arrival of rescue teams. The proposed novel approach in emergency communications enables survivors to communicate among themselves and help each other. Here, the idea of a selforganizing network is put forward, which makes use of available network resources formally occupied by the destroyed and / or damaged telecommunications’ infrastructure. In our post-disaster scenario, mobile nodes establish a self-organizing / ad hoc network which provides critical level of communications among disaster victims needed at that time and consequently tries to merge with some surviving telecommunications infrastructure and / or network deployed by rescue teams. The outcome of this paper is a fundamentally novel idea for immediate postdisaster communications. This idea is tested through some network survivability measures and hypothesis testing. We also test the working of this ad hoc network through simulation for post-disaster scenarios of partially and fully destroyed networks. The results obtained are found to be satisfactory and within acceptable limits of ad hoc networks.
On Redundancy Elimination Tolerant Scheduling Rules  [PDF]
F. Ferrucci,G. Pacini,M. I. Sessa
Computer Science , 2000,
Abstract: In (Ferrucci, Pacini and Sessa, 1995) an extended form of resolution, called Reduced SLD resolution (RSLD), is introduced. In essence, an RSLD derivation is an SLD derivation such that redundancy elimination from resolvents is performed after each rewriting step. It is intuitive that redundancy elimination may have positive effects on derivation process. However, undesiderable effects are also possible. In particular, as shown in this paper, program termination as well as completeness of loop checking mechanisms via a given selection rule may be lost. The study of such effects has led us to an analysis of selection rule basic concepts, so that we have found convenient to move the attention from rules of atom selection to rules of atom scheduling. A priority mechanism for atom scheduling is built, where a priority is assigned to each atom in a resolvent, and primary importance is given to the event of arrival of new atoms from the body of the applied clause at rewriting time. This new computational model proves able to address the study of redundancy elimination effects, giving at the same time interesting insights into general properties of selection rules. As a matter of fact, a class of scheduling rules, namely the specialisation independent ones, is defined in the paper by using not trivial semantic arguments. As a quite surprising result, specialisation independent scheduling rules turn out to coincide with a class of rules which have an immediate structural characterisation (named stack-queue rules). Then we prove that such scheduling rules are tolerant to redundancy elimination, in the sense that neither program termination nor completeness of equality loop check is lost passing from SLD to RSLD.
Partial Redundancy Elimination for Multi-threaded Programs  [PDF]
Mohamed A. El-Zawawy,Hamada A. Nayel
Computer Science , 2011,
Abstract: Multi-threaded programs have many applications which are widely used such as operating systems. Analyzing multi-threaded programs differs from sequential ones; the main feature is that many threads execute at the same time. The effect of all other running threads must be taken in account. Partial redundancy elimination is among the most powerful compiler optimizations: it performs loop-invariant code motion and common subexpression elimination. We present a type system with optimization component which performs partial redundancy elimination for multi-threaded programs.
In-Network Caching vs. Redundancy Elimination  [PDF]
Liang Wang,Walter Wong,Jussi Kangasharju
Computer Science , 2013,
Abstract: Network-level Redundancy Elimination (RE) techniques have been proposed to reduce the amount of traffic in the Internet. and the costs of the WAN access in the Internet. RE middleboxes are usually placed in the network access gateways and strip off the repeated data from the packets. More recently, generic network-level caching architectures have been proposed as alternative to reduce the redundant data traffic in the network, presenting benefits and drawbacks compared to RE. In this paper, we compare a generic in-network caching architecture against state-of-the-art redundancy elimination (RE) solutions on real network topologies, presenting the advantages of each technique. Our results show that in-network caching architectures outperform state-of-the-art RE solutions across a wide range of traffic characteristics and parameters.
READA: Redundancy Elimination for Accurate Data Aggregation in Wireless Sensor Networks  [PDF]
Kavi Khedo, Rubeena Doomun, Sonum Aucharuz
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.24041
Abstract: In monitoring systems, multiple sensor nodes can detect a single target of interest simultaneously and the data collected are usually highly correlated and redundant. If each node sends data to the base station, energy will be wasted and thus the network energy will be depleted quickly. Data aggregation is an important paradigm for compressing data so that the energy of the network is spent efficiently. In this paper, a novel data aggregation algorithm called Redundancy Elimination for Accurate Data Aggregation (READA) has been proposed. By exploiting the range of spatial correlations of data in the network, READA applies a grouping and compression mechanism to remove duplicate data in the aggregated set of data to be sent to the base station without largely losing the accuracy of the final aggregated data. One peculiarity of READA is that it uses a prediction model derived from cached values to confirm whether any outlier is actually an event which has occurred. From the various simulations conducted, it was observed that in READA the accuracy of data has been highly preserved taking into consideration the energy dissipated for aggregating the data
Disaster and emergency communications prior to computers/Internet: a review
John W Farnham
Critical Care , 2005, DOI: 10.1186/cc3944
Abstract: It is a virtually immutable universal law that when communications are needed the most desperately and urgently, the difficulty of effecting the desired communication increases exponentially. Examples in our immediate experience include the South Asia tsunami, Hurricanes Katrina and Rita in the USA, the South Asian earthquake in Pakistan, India, and Afghanistan, and the mudslides in Guatemala.The history of disaster communications before computers or the Internet (or outside the realm of the Internet) provides us with a long-standing testament to this sad fact. The English word 'disaster' comes from a Greek prefix and root word meaning 'bad star'. This harks back to the notion that calamitous things happen under the influence of bad star alignment. No matter the level of faith one puts in the alignment of stars as affecting events on earth, the history of the effort to communicate over distances is inextricably rooted in the motivation to avoid, or at least mitigate, the effects of various disasters. The modern ability to chat casually or to be entertained by communication technology is but an offshoot of the development of that technology which first permitted priority communication about more urgent matters.Acknowledging some of the earlier aspects of disaster or emergency communications can be interesting and engaging, and it can enable us to understand the fundamental need to communicate about emergent events. Although much of this review is oriented to history in the USA, there were parallel activities occurring in all countries in which the new technology of radio existed. Hopefully, my geocentrism in this review in an international medium can be understood and pardoned in light of that fact.Considerably predating the discovery of radio waves, many peoples had developed means of telegraphy within the broadest sense of the word. The word 'telegraph' has as its origin the union of another two Greek words that essentially mean 'long-distance writing'. Smoke signa
Benefit of Selecting Number of Active Mesh Routers in Disaster Oriented Wireless Mesh Network  [PDF]
Panu Avakul, Hiroki Nishiyama, Nei Kato, Yoshitaka Shimizu, Tomoaki Kumagai
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.512B008
Abstract: Communications is one of the most critical factors in disaster recovery process. However, after a major disaster, existing communications infrastructures may be heavily damaged or even completely unusable. It is necessary that communicationsare to be promptly restored to the disaster area, which is the goal of our national project. The project aims to build three tiers wireless mesh network from remaining wireless access points in order to provide communications services to the disaster area. This work introduces a unique multiple tiers wireless mesh network project. In addition, this work also illustrates merits in optimizing the number of mesh routersin order to achieve the optimum performance by presenting both theoretical and simulation results of a specific scenario of multiple tiers wireless mesh network.
Dynamics of disaster spreading in complex networks
复杂网络上灾害蔓延动力学研究

Weng Wen-Guo,Ni Shun-Jiang,Shen Shi-Fei,Yuan Hong-Yong,
翁文国
,倪顺江,申世飞,袁宏永

物理学报 , 2007,
Abstract: A general dynamical model for disaster spreading is established in this paper, aiming at some common characteristics of key lifeline systems such as power supply network, water supply network, gas supply network, traffic network and communications network, etc. This model considers self-healing function, disaster spreading mechanism and internal stochastic noise of nodes. And the effects of three key parameters,namely the self-healing factor, duration delay factor and noise intensity, on recovery rate and number of damaged nodes for three different network topologies, i.e. Erdos-Renyi network, scale-free network and small world network are investigated. Simulation results are consistent with the characteristics of these true lifeline systems, showing that the presented model can effectively model disaster evolving dynamics for lifeline systems.
Emergency Response Communications and Associated Security Challenges  [PDF]
Muhammad Ibrahim Channa,Kazi M. Ahmed
Computer Science , 2010,
Abstract: The natural or man-made disaster demands an efficient communication and coordination among first responders to save life and other community resources. Normally, the traditional communication infrastructures such as land line or cellular networks are damaged and don't provide adequate communication services to first responders for exchanging emergency related information. Wireless ad hoc networks such as mobile ad hoc networks, wireless sensor networks and wireless mesh networks are the promising alternatives in such type of situations. The security requirements for emergency response communications include privacy, data integrity, authentication, key management, access control and availability. Various ad hoc communication frameworks have been proposed for emergency response situations. The majority of the proposed frameworks don't provide adequate security services for reliable and secure information exchange. This paper presents a survey of the proposed emergency response communication frameworks and the potential security services required by them to provide reliable and secure information exchange during emergency situations.
Broadcasting with Least Redundancy in Wireless Sensor Networks  [PDF]
Ruiqin Zhao,Xiaohong Shen,Zhe Jiang,Haiyan Wang
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/957606
Abstract: In wireless sensor networks (WSN), broadcasting could allow the nodes to share their data efficiently. Due to the limited energy supply of each sensor node, it has become a crucial issue to minimize energy consumption and maximize the network lifetime in the design of broadcast protocols. In this paper, we propose a Broadcast Algorithm with Least Redundancy (BALR) for WSN. By identifying the optimized number of induced forwarders as 2, BALR establishes a weighted sum model, taking both rebroadcast efficiency and residual energy into consideration, as a new metric to compute the self-delay of the nodes before rebroadcasting. BALR further incorporates both strategies based on distance and coverage degree which means the number of neighbors that have not yet received the broadcast packet, to optimize the rebroadcast node selections. To reveal the performance bounds, rebroadcast ratios in the ideal and worst case are theoretically analyzed, indicating that the rebroadcast ratio of BALR decreases with the increase of node density. BALR can significantly prolong the network lifetime of WSN and is scalable with respect to network size and node density, as demonstrated by simulations. 1. Introduction Wireless sensor networks (WSN) are envisioned as consisting of a number of static sensor nodes that are densely deployed over a region of interest. A wide variety of applications of such networks include inventory managing, disaster areas monitoring, patient assisting, water quality monitoring, target tracking, and health monitoring of civil infrastructures. Recent advances in wireless communications and electronics have enabled the development of such low-cost sensor networks. Unfortunately, wireless sensor nodes, which are generally microelectronic devices, could only be equipped with limited power sources. Therefore, energy efficiency is of particular importance in WSN [1–4]. Broadcasting is a common means for nodes in WSN to efficiently share their data with each other. Broadcasting could be utilized to initialize the network configuration for network discovery, discover multiple routes between a given pair of nodes, and query for a piece of desired data in a network [5]. In WSN, broadcasting could also be served as an efficient approach for sensors to share their local measurements with each other. A straightforward way of broadcasting is the so-called flooding, under which each node will rebroadcast when it receives the broadcast packet for the first time. Although attractive for its simplicity, flooding will cause serious broadcast redundancy, packets
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