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Sample records for hoc tests showed

  1. simulate_CAT: A Computer Program for Post-Hoc Simulation for Computerized Adaptive Testing

    Directory of Open Access Journals (Sweden)

    İlker Kalender

    2015-06-01

    Full Text Available This paper presents a computer software developed by the author. The software conducts post-hoc simulations for computerized adaptive testing based on real responses of examinees to paper and pencil tests under different parameters that can be defined by user. In this paper, short information is given about post-hoc simulations. After that, the working principle of the software is provided and a sample simulation with required input files is shown. And last, output files are described

  2. Recreating the seawater mixture composition of HOCs in toxicity tests with Artemia franciscana by passive dosing

    Energy Technology Data Exchange (ETDEWEB)

    Rojo-Nieto, E., E-mail: elisa.rojo@uca.es [Andalusian Centre of Marine Science and Technology (CACYTMAR), Department of Environmental Technologies, University of Cadiz, 11510 Puerto Real (Spain); Smith, K.E.C. [Department of Environmental Science, Aarhus University, DK-4000 Roskilde (Denmark); Perales, J.A. [Andalusian Centre of Marine Science and Technology (CACYTMAR), Department of Environmental Technologies, University of Cadiz, 11510 Puerto Real (Spain); Mayer, P. [Department of Environmental Science, Aarhus University, DK-4000 Roskilde (Denmark)

    2012-09-15

    The toxicity testing of hydrophobic organic compounds (HOCs) in aquatic media is generally challenging, and this is even more problematic for mixtures. The hydrophobic properties of these compounds make them difficult to dissolve, and subsequently to maintain constant exposure concentrations. Evaporative and sorptive losses are highly compound-specific, which can alter not only total concentrations, but also the proportions between the compounds in the mixture. Therefore, the general aim of this study was to explore the potential of passive dosing for testing the toxicity of a PAH mixture that recreates the mixture composition found in seawater from a coastal area of Spain, the Bay of Algeciras. First, solvent spiking and passive dosing were compared for their suitability to determine the acute toxicity to Artemia franciscana nauplii of several PAHs at their respective solubility limits. Second, passive dosing was applied to recreate the seawater mixture composition of PAHs measured in a Spanish monitoring program, to test the toxicity of this mixture at different levels. HPLC analysis was used to confirm the reproducibility of the dissolved exposure concentrations for the individual PAHs and mixtures. This study shows that passive dosing has some important benefits in comparison with solvent spiking for testing HOCs in aquatic media. These include maintaining constant exposure concentrations, leading to higher reproducibility and a relative increase in toxicity. Passive dosing is also able to faithfully reproduce real mixtures of HOCs such as PAHs, in toxicity tests, reproducing both the levels and proportions of the different compounds. This provides a useful approach for studying the toxicity of environmental mixtures of HOCs, both with a view to investigating their toxicity but also for determining safety factors before such mixtures result in detrimental effects.

  3. New grid based test bed environment for carrying out ad-hoc networking experiments

    CSIR Research Space (South Africa)

    Johnson, D

    2006-09-01

    Full Text Available and the third is to do analysis on a real test bed network which has implemented the ad-hoc networking protocol. This paper concerns the third option. Most researchers who have done work on test bed environments have used either indoor Wifi inter-office links...

  4. Ad hoc laser networks component technology for modular spacecraft

    Science.gov (United States)

    Huang, Xiujun; Shi, Dele; Shen, Jingshi

    2017-10-01

    Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

  5. Illustrating, Quantifying, and Correcting for Bias in Post-hoc Analysis of Gene-Based Rare Variant Tests of Association

    Directory of Open Access Journals (Sweden)

    Kelsey E. Grinde

    2017-09-01

    Full Text Available To date, gene-based rare variant testing approaches have focused on aggregating information across sets of variants to maximize statistical power in identifying genes showing significant association with diseases. Beyond identifying genes that are associated with diseases, the identification of causal variant(s in those genes and estimation of their effect is crucial for planning replication studies and characterizing the genetic architecture of the locus. However, we illustrate that straightforward single-marker association statistics can suffer from substantial bias introduced by conditioning on gene-based test significance, due to the phenomenon often referred to as “winner's curse.” We illustrate the ramifications of this bias on variant effect size estimation and variant prioritization/ranking approaches, outline parameters of genetic architecture that affect this bias, and propose a bootstrap resampling method to correct for this bias. We find that our correction method significantly reduces the bias due to winner's curse (average two-fold decrease in bias, p < 2.2 × 10−6 and, consequently, substantially improves mean squared error and variant prioritization/ranking. The method is particularly helpful in adjustment for winner's curse effects when the initial gene-based test has low power and for relatively more common, non-causal variants. Adjustment for winner's curse is recommended for all post-hoc estimation and ranking of variants after a gene-based test. Further work is necessary to continue seeking ways to reduce bias and improve inference in post-hoc analysis of gene-based tests under a wide variety of genetic architectures.

  6. Game Theory in Wireless Ad-Hoc Opportunistic Radios

    OpenAIRE

    Mumtaz, Shahid; Gameiro, Atilio

    2010-01-01

    Emerging research in game theory based power control applied to ad hoc opportunist networks shows much promise to help understand the complex interactions between OR nodes in this highly dynamic and distributed environment. Also, the employment of game theory in modeling dynamic situations for opportunist ad hoc networks where OR nodes have incomplete information has led to the application of largely unexplored games such as games of imperfect monitoring. Ad hoc security using game theory is ...

  7. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks.

    Science.gov (United States)

    Al-Nahari, Abdulaziz; Mohamad, Mohd Murtadha

    2016-01-01

    Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV), which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV) protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV.

  8. Extending Service Area of IEEE 802.11 Ad Hoc Networks

    Science.gov (United States)

    Choi, Woo-Yong

    2012-06-01

    According to the current IEEE 802.11 wireless LAN standards, IEEE 802.11 ad hoc networks have the limitation that all STAs (Stations) are in the one-hop transmission range of each other. In this paper, to alleviate the limitation of IEEE 802.11 ad hoc networks we propose the efficient method for selecting the most appropriate pseudo AP (Access Point) from among the set of ad hoc STAs and extending the service area of IEEE 802.11 ad hoc networks by the pseudo AP's relaying the internal traffic of IEEE 802.11 ad hoc networks. Numerical examples show that the proposed method significantly extends the service area of IEEE 802.11 ad hoc networks.

  9. AD HOC Networks for the Autonomous Car

    Science.gov (United States)

    Ron, Davidescu; Negrus, Eugen

    2017-10-01

    The future of the vehicle is made of cars, roads and infrastructures connected in a two way automated communication in a holistic system. It is a mandatory to use Encryption to maintain Confidentiality, Integrity and Availability in an ad hoc vehicle network. Vehicle to Vehicle communication, requires multichannel interaction between mobile, moving and changing parties to insure the full benefit from data sharing and real time decision making, a network of such users referred as mobile ad hoc network (MANET), however as ad hoc networks were not implemented in such a scale, it is not clear what is the best method and protocol to apply. Furthermore the visibility of secure preferred asymmetric encrypted ad hoc networks in a real time environment of dense moving autonomous vehicles has to be demonstrated, In order to evaluate the performance of Ad Hoc networks in changing conditions a simulation of multiple protocols was performed on large number of mobile nodes. The following common routing protocols were tested, DSDV is a proactive protocol, every mobile station maintains a routing table with all available destinations, DSR is a reactive routing protocol which allows nodes in the MANET to dynamically discover a source route across multiple network hops, AODV is a reactive routing protocol Instead of being proactive. It minimizes the number of broadcasts by creating routes based on demand, SAODV is a secure version of AODV, requires heavyweight asymmetric cryptographic, ARIANDE is a routing protocol that relies on highly efficient symmetric cryptography the concept is primarily based on DSR. A methodical evolution was performed in a various density of transportation, based on known communication bench mark parameters including, Throughput Vs. time, Routing Load per packets and bytes. Out of the none encrypted protocols, It is clear that in terms of performance of throughput and routing load DSR protocol has a clear advantage the high node number mode. The encrypted

  10. Routing Protocol for Mobile Ad-hoc Wireless Networks

    Directory of Open Access Journals (Sweden)

    I. M. B. Nogales

    2007-09-01

    Full Text Available Bluetooth is a cutting-edge technology used for implementing wireless ad hoc networks. In order to provide an overall scheme for mobile ad hoc networks, this paper deals with scatternet topology formation and routing algorithm to form larger ad hoc wireless Networks. Scatternet topology starts by forming a robust network, which is less susceptible to the problems posed by node mobility. Mobile topology relies on the presence of free nodes that create multiple connections with the network and on their subsequently rejoining the network. Our routing protocol is a proactive routing protocol, which is tailor made for the Bluetooth ad hoc network. The connection establishment connects nodes in a structure that simplifies packet routing and scheduling. The design allows nodes to arrive and leave arbitrarily, incrementally building the topology and healing partitions when they occur. We present simulation results that show that the algorithm presents low formation latency and also generates an efficient topology for forwarding packets along ad-hoc wireless networks.

  11. Student Self-Assessment in HOCS Science Examinations: Is There a Problem?

    Science.gov (United States)

    Zoller, Uri; Ben-Chaim, David

    1998-06-01

    A specially-designed self-assessment questionnaire (SAQHOCS), containing higher-order cognitive skills (HOCS)-type questions, was administered to 71 biology majors, enrolled in a four-year college program. The gap between students' self-assessment marking, and that of their HOCS-biased teachers (the authors), is accounted for by the prevailing LOCS-orientation and the "testing culture"—a total separation between testing and learning—in contemporary science teaching. The majority of the students in the study evaluated themselves as capable of self-assessment, and felt reasonably confident in doing so. They were quite reserved as far as the applicability of the self-assessment method to nonalgorithmic ("correct/incorrect") questions is concerned. The results of this study suggest that the potential for student self-assessment within college science teaching and learning exists. However, still a great purposed effort in HOCS-oriented teaching and learning is required in order for the student self-assessment practice to become a routine integral component of HOCS science examinations.

  12. Ad-hoc networking towards seamless communications

    CERN Document Server

    Gavrilovska, Liljana

    2006-01-01

    Ad-Hoc Networking Towards Seamless Communications is dedicated to an area that attracts growing interest in academia and industry and concentrates on wireless ad hoc networking paradigm. The persistent efforts to acquire the ability to establish dynamic wireless connections from anywhere to anyone with any device without prerequisite imbedded infrastructure move the communications boundaries towards ad-hoc networks. Recently, ad hoc networking has attracted growing interest due to advances in wireless communications, and developed framework for running IP based protocols. The expected degree of penetration of these networks will depend on the successful resolution of the key features. Ad-hoc networks pose many complex and open problems for researchers. Ad-Hoc Networking Towards Seamless Communications reveals the state-of-the-art in wireless ad-hoc networking and discusses some of the key research topics that are expected to promote and accelerate the commercial applications of these networks (e.g., MAC, rout...

  13. Illustrating, Quantifying, and Correcting for Bias in Post-hoc Analysis of Gene-Based Rare Variant Tests of Association

    Science.gov (United States)

    Grinde, Kelsey E.; Arbet, Jaron; Green, Alden; O'Connell, Michael; Valcarcel, Alessandra; Westra, Jason; Tintle, Nathan

    2017-01-01

    To date, gene-based rare variant testing approaches have focused on aggregating information across sets of variants to maximize statistical power in identifying genes showing significant association with diseases. Beyond identifying genes that are associated with diseases, the identification of causal variant(s) in those genes and estimation of their effect is crucial for planning replication studies and characterizing the genetic architecture of the locus. However, we illustrate that straightforward single-marker association statistics can suffer from substantial bias introduced by conditioning on gene-based test significance, due to the phenomenon often referred to as “winner's curse.” We illustrate the ramifications of this bias on variant effect size estimation and variant prioritization/ranking approaches, outline parameters of genetic architecture that affect this bias, and propose a bootstrap resampling method to correct for this bias. We find that our correction method significantly reduces the bias due to winner's curse (average two-fold decrease in bias, p bias and improve inference in post-hoc analysis of gene-based tests under a wide variety of genetic architectures. PMID:28959274

  14. The 11th Annual Mediterranean Ad Hoc Networking Workshop (Med-Hoc-Net 2012)

    NARCIS (Netherlands)

    Pitsillides, A.; Douligeris, C.; Vassiliou, V.; Heijenk, Geert; Cavalcante de Oliveira, J.

    Message from the General Chairs Welcome to the 2012 Mediterranean Ad Hoc Networking Workshop in Ayia Napa, Cyprus. We are excited to host Med-Hoc-Net. As a major annual international workshop, following recent successful workshops in Sicily (2006), Corfu (2007), Palma de Mallorca (2008), Haifa

  15. Mobile ad hoc networking

    CERN Document Server

    John Wiley & Sons

    2004-01-01

    "Assimilating the most up-to-date information on research and development activities in this rapidly growing area, Mobile Ad Hoc Networking covers physical, data link, network, and transport layers, as well as application, security, simulation, and power management issues in sensor, local area, personal, and mobile ad hoc networks. Each of the book's sixteen chapters has been written by a top expert and discusses in-depth the most important topics in the field. Mobile Ad Hoc Networking is an excellent reference and guide for professionals seeking an in-depth examination of topics that also provides a comprehensive overview of the current state-of-the-art."--Jacket.

  16. A SAS(®) macro implementation of a multiple comparison post hoc test for a Kruskal-Wallis analysis.

    Science.gov (United States)

    Elliott, Alan C; Hynan, Linda S

    2011-04-01

    The Kruskal-Wallis (KW) nonparametric analysis of variance is often used instead of a standard one-way ANOVA when data are from a suspected non-normal population. The KW omnibus procedure tests for some differences between groups, but provides no specific post hoc pair wise comparisons. This paper provides a SAS(®) macro implementation of a multiple comparison test based on significant Kruskal-Wallis results from the SAS NPAR1WAY procedure. The implementation is designed for up to 20 groups at a user-specified alpha significance level. A Monte-Carlo simulation compared this nonparametric procedure to commonly used parametric multiple comparison tests. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  17. A flow level model for wireless multihop ad hoc network throughput

    NARCIS (Netherlands)

    Coenen, Tom Johannes Maria; van den Berg, Hans Leo; Boucherie, Richardus J.

    2005-01-01

    A flow level model for multihop wireless ad hoc networks is presented in this paper. Using a flow level view, we show the main properties and modeling challenges for ad hoc networks. Considering different scenarios, a multihop WLAN and a serial network with a TCP-like flow control protocol, we

  18. Analysis for Ad Hoc Network Attack-Defense Based on Stochastic Game Model

    Directory of Open Access Journals (Sweden)

    Yuanjie LI

    2014-06-01

    Full Text Available The attack actions analysis for Ad Hoc networks can provide a reference for the design security mechanisms. This paper presents an analysis method of security of Ad Hoc networks based on Stochastic Game Nets (SGN. This method can establish a SGN model of Ad Hoc networks and calculate to get the Nash equilibrium strategy. After transforming the SGN model into a continuous-time Markov Chain (CTMC, the security of Ad Hoc networks can be evaluated and analyzed quantitatively by calculating the stationary probability of CTMC. Finally, the Matlab simulation results show that the probability of successful attack is related to the attack intensity and expected payoffs, but not attack rate.

  19. Intrusion detection in wireless ad-hoc networks

    CERN Document Server

    Chaki, Nabendu

    2014-01-01

    Presenting cutting-edge research, Intrusion Detection in Wireless Ad-Hoc Networks explores the security aspects of the basic categories of wireless ad-hoc networks and related application areas. Focusing on intrusion detection systems (IDSs), it explains how to establish security solutions for the range of wireless networks, including mobile ad-hoc networks, hybrid wireless networks, and sensor networks.This edited volume reviews and analyzes state-of-the-art IDSs for various wireless ad-hoc networks. It includes case studies on honesty-based intrusion detection systems, cluster oriented-based

  20. Ad Hoc Access Gateway Selection Algorithm

    Science.gov (United States)

    Jie, Liu

    With the continuous development of mobile communication technology, Ad Hoc access network has become a hot research, Ad Hoc access network nodes can be used to expand capacity of multi-hop communication range of mobile communication system, even business adjacent to the community, improve edge data rates. For mobile nodes in Ad Hoc network to internet, internet communications in the peer nodes must be achieved through the gateway. Therefore, the key Ad Hoc Access Networks will focus on the discovery gateway, as well as gateway selection in the case of multi-gateway and handover problems between different gateways. This paper considers the mobile node and the gateway, based on the average number of hops from an average access time and the stability of routes, improved gateway selection algorithm were proposed. An improved gateway selection algorithm, which mainly considers the algorithm can improve the access time of Ad Hoc nodes and the continuity of communication between the gateways, were proposed. This can improve the quality of communication across the network.

  1. Dynamic ad hoc networks

    CERN Document Server

    Rashvand, Habib

    2013-01-01

    Motivated by the exciting new application paradigm of using amalgamated technologies of the Internet and wireless, the next generation communication networks (also called 'ubiquitous', 'complex' and 'unstructured' networking) are changing the way we develop and apply our future systems and services at home and on local, national and global scales. Whatever the interconnection - a WiMAX enabled networked mobile vehicle, MEMS or nanotechnology enabled distributed sensor systems, Vehicular Ad hoc Networking (VANET) or Mobile Ad hoc Networking (MANET) - all can be classified under new networking s

  2. Ad Hoc Categories and False Memories: Memory Illusions for Categories Created On-The-Spot

    Science.gov (United States)

    Soro, Jerônimo C.; Ferreira, Mário B.; Semin, Gün R.; Mata, André; Carneiro, Paula

    2017-01-01

    Three experiments were designed to test whether experimentally created ad hoc associative networks evoke false memories. We used the DRM (Deese, Roediger, McDermott) paradigm with lists of ad hoc categories composed of exemplars aggregated toward specific goals (e.g., going for a picnic) that do not share any consistent set of features. Experiment…

  3. A Clustering Routing Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Jinke Huang

    2016-01-01

    Full Text Available The dynamic topology of a mobile ad hoc network poses a real challenge in the design of hierarchical routing protocol, which combines proactive with reactive routing protocols and takes advantages of both. And as an essential technique of hierarchical routing protocol, clustering of nodes provides an efficient method of establishing a hierarchical structure in mobile ad hoc networks. In this paper, we designed a novel clustering algorithm and a corresponding hierarchical routing protocol for large-scale mobile ad hoc networks. Each cluster is composed of a cluster head, several cluster gateway nodes, several cluster guest nodes, and other cluster members. The proposed routing protocol uses proactive protocol between nodes within individual clusters and reactive protocol between clusters. Simulation results show that the proposed clustering algorithm and hierarchical routing protocol provide superior performance with several advantages over existing clustering algorithm and routing protocol, respectively.

  4. Packets Distributing Evolutionary Algorithm Based on PSO for Ad Hoc Network

    Science.gov (United States)

    Xu, Xiao-Feng

    2018-03-01

    Wireless communication network has such features as limited bandwidth, changeful channel and dynamic topology, etc. Ad hoc network has lots of difficulties in accessing control, bandwidth distribution, resource assign and congestion control. Therefore, a wireless packets distributing Evolutionary algorithm based on PSO (DPSO)for Ad Hoc Network is proposed. Firstly, parameters impact on performance of network are analyzed and researched to obtain network performance effective function. Secondly, the improved PSO Evolutionary Algorithm is used to solve the optimization problem from local to global in the process of network packets distributing. The simulation results show that the algorithm can ensure fairness and timeliness of network transmission, as well as improve ad hoc network resource integrated utilization efficiency.

  5. Context discovery in ad-hoc networks

    NARCIS (Netherlands)

    Liu, F.

    2011-01-01

    With the rapid development of wireless technology and portable devices, mobile ad-hoc networks (MANETs) are more and more present in our daily life. Ad-hoc networks are often composed of mobile and battery-supplied devices, like laptops, mobile phones, and PDAs. With no requirement for

  6. Research of Ad Hoc Networks Access Algorithm

    Science.gov (United States)

    Xiang, Ma

    With the continuous development of mobile communication technology, Ad Hoc access network has become a hot research, Ad Hoc access network nodes can be used to expand capacity of multi-hop communication range of mobile communication system, even business adjacent to the community, improve edge data rates. When the ad hoc network is the access network of the internet, the gateway discovery protocol is very important to choose the most appropriate gateway to guarantee the connectivity between ad hoc network and IP based fixed networks. The paper proposes a QoS gateway discovery protocol which uses the time delay and stable route to the gateway selection conditions. And according to the gateway discovery protocol, it also proposes a fast handover scheme which can decrease the handover time and improve the handover efficiency.

  7. A Group Based Key Sharing and Management Algorithm for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Zeeshan Shafi Khan

    2014-01-01

    Full Text Available Vehicular ad hoc networks (VANETs are one special type of ad hoc networks that involves vehicles on roads. Typically like ad hoc networks, broadcast approach is used for data dissemination. Blind broadcast to each and every node results in exchange of useless and irrelevant messages and hence creates an overhead. Unicasting is not preferred in ad-hoc networks due to the dynamic topology and the resource requirements as compared to broadcasting. Simple broadcasting techniques create several problems on privacy, disturbance, and resource utilization. In this paper, we propose media mixing algorithm to decide what information should be provided to each user and how to provide such information. Results obtained through simulation show that fewer number of keys are needed to share compared to simple broadcasting. Privacy is also enhanced through this approach.

  8. Cytoarchitecture of the human lateral occipital cortex: mapping of two extrastriate areas hOc4la and hOc4lp.

    Science.gov (United States)

    Malikovic, Aleksandar; Amunts, Katrin; Schleicher, Axel; Mohlberg, Hartmut; Kujovic, Milenko; Palomero-Gallagher, Nicola; Eickhoff, Simon B; Zilles, Karl

    2016-05-01

    The microstructural correlates of the functional segregation of the human lateral occipital cortex are largely unknown. Therefore, we analyzed the cytoarchitecture of this region in ten human post-mortem brains using an observer-independent and statistically testable parcellation method to define the position and extent of areas in the lateral occipital cortex. Two new cytoarchitectonic areas were found: an anterior area hOc4la and a posterior area hOc4lp. hOc4la was located behind the anterior occipital sulcus in rostral and ventral portions of this region where it occupies the anterior third of the middle and inferior lateral occipital gyri. hOc4lp was found in caudal and dorsal portions of this region where it extends along the superior and middle lateral occipital gyri. The cytoarchitectonic areas were registered to 3D reconstructions of the corresponding brains, which were subsequently spatially normalized to the Montreal Neurological Institute reference space. Continuous probabilistic maps of both areas based on the analysis of ten brains were generated to characterize their inter-subject variability in location and size. The maps of hOc4la and hOc4lp were then used as seeds for meta-analytic connectivity modeling and quantitative functional decoding to identify their co-activation patterns and assignment to functional domains. Convergent evidence from their location, topography, size, functional domains and connectivity indicates that hOc4la and hOc4lp are the potential anatomical correlates of the functionally defined lateral occipital areas LO-1 and LO-2.

  9. NDN-CRAHNs: Named Data Networking for Cognitive Radio Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Rana Asif Rehman

    2015-01-01

    Full Text Available Named data networking (NDN is a newly proposed paradigm for future Internet, in which communication among nodes is based on data names, decoupling from their locations. In dynamic and self-organized cognitive radio ad hoc networks (CRAHNs, it is difficult to maintain end-to-end connectivity between ad hoc nodes especially in the presence of licensed users and intermittent wireless channels. Moreover, IP-based CRAHNs have several issues like scalability, inefficient-mapping, poor resource utilization, and location dependence. By leveraging the advantages of NDN, in this paper, we propose a new cross layer fine-grained architecture called named data networking for cognitive radio ad hoc networks (NDN-CRAHNs. The proposed architecture provides distinct features such as in-networking caching, security, scalability, and multipath routing. The performances of the proposed scheme are evaluated comparing to IP-based scheme in terms of average end-to-end delay and packet delivery ratio. Simulation results show that the proposed scheme is effective in terms of average contents download time and packet delivery ratios comparing to conventional cognitive radio ad hoc networks.

  10. A Tool for Visualizing Mobile Ad-Hoc Network Topology Definitions Files

    National Research Council Canada - National Science Library

    Nguyen, Binh Q

    2006-01-01

    This report documents a research and development effort that the U.S. Army Research Laboratory conducted in FY05 in support of the building of an emulated tactical mobile ad hoc network (MANET) research test bed...

  11. Interference in wireless ad hoc networks with smart antennas

    KAUST Repository

    Alabdulmohsin, Ibrahim

    2014-01-01

    In this paper, we show that the use of directional antennas in wireless ad hoc networks can actually increase interference due to limitations of virtual carrier sensing. We derive a simple mathematical expression for interference in both physical

  12. Taxonomic and ad hoc categorization within the two cerebral hemispheres.

    Science.gov (United States)

    Shen, Yeshayahu; Aharoni, Bat-El; Mashal, Nira

    2015-01-01

    A typicality effect refers to categorization which is performed more quickly or more accurately for typical than for atypical members of a given category. Previous studies reported a typicality effect for category members presented in the left visual field/right hemisphere (RH), suggesting that the RH applies a similarity-based categorization strategy. However, findings regarding the typicality effect within the left hemisphere (LH) are less conclusive. The current study tested the pattern of typicality effects within each hemisphere for both taxonomic and ad hoc categories, using words presented to the left or right visual fields. Experiment 1 tested typical and atypical members of taxonomic categories as well as non-members, and Experiment 2 tested typical and atypical members of ad hoc categories as well as non-members. The results revealed a typicality effect in both hemispheres and in both types of categories. Furthermore, the RH categorized atypical stimuli more accurately than did the LH. Our findings suggest that both hemispheres rely on a similarity-based categorization strategy, but the coarse semantic coding of the RH seems to facilitate the categorization of atypical members.

  13. AD HOC TEAMWORK BEHAVIORS FOR INFLUENCING A FLOCK

    Directory of Open Access Journals (Sweden)

    Katie Genter

    2016-02-01

    Full Text Available Ad hoc teamwork refers to the challenge of designing agents that can influence the behavior of a team, without prior coordination with its teammates. This paper considers influencing a flock of simple robotic agents to adopt a desired behavior within the context of ad hoc teamwork. Specifically, we examine how the ad hoc agents should behave in order to orient a flock towards a target heading as quickly as possible when given knowledge of, but no direct control over, the behavior of the flock. We introduce three algorithms which the ad hoc agents can use to influence the flock, and we examine the relative importance of coordinating the ad hoc agents versus planning farther ahead when given fixed computational resources. We present detailed experimental results for each of these algorithms, concluding that in this setting, inter-agent coordination and deeper lookahead planning are no more beneficial than short-term lookahead planning.

  14. Queueing Models for Mobile Ad Hoc Networks

    NARCIS (Netherlands)

    de Haan, Roland

    2009-01-01

    This thesis presents models for the performance analysis of a recent communication paradigm: \\emph{mobile ad hoc networking}. The objective of mobile ad hoc networking is to provide wireless connectivity between stations in a highly dynamic environment. These dynamics are driven by the mobility of

  15. Assured Resource Sharing in Ad-Hoc Collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Gail-Joon [Arizona State Univ., Tempe, AZ (United States)

    2015-12-19

    The project seeks an innovative framework to enable users to access and selectively share resources in distributed environments, enhancing the scalability of information sharing. We have investigated secure sharing & assurance approaches for ad-hoc collaboration, focused on Grids, Clouds, and ad-hoc network environments.

  16. Information Sharing Modalities for Mobile Ad-Hoc Networks

    Science.gov (United States)

    de Spindler, Alexandre; Grossniklaus, Michael; Lins, Christoph; Norrie, Moira C.

    Current mobile phone technologies have fostered the emergence of a new generation of mobile applications. Such applications allow users to interact and share information opportunistically when their mobile devices are in physical proximity or close to fixed installations. It has been shown how mobile applications such as collaborative filtering and location-based services can take advantage of ad-hoc connectivity to use physical proximity as a filter mechanism inherent to the application logic. We discuss the different modes of information sharing that arise in such settings based on the models of persistence and synchronisation. We present a platform that supports the development of applications that can exploit these modes of ad-hoc information sharing and, by means of an example, show how such an application can be realised based on the supported event model.

  17. Secure Geographic Routing in Ad Hoc and Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Zahariadis Theodore

    2010-01-01

    Full Text Available Security in sensor networks is one of the most relevant research topics in resource constrained wireless devices and networks. Several attacks can be suffered in ad hoc and wireless sensor networks (WSN, which are highly susceptible to attacks, due to the limited resources of the nodes. In this paper, we propose innovative and lightweight localization techniques that allow for intrusion identification and isolation schemes and provide accurate location information. This information is used by our routing protocol which additionally incorporates a distributed trust model to prevent several routing attacks to the network. We finally evaluate our algorithms for accurate localization and for secure routing which have been implemented and tested in real ad hoc and wireless sensor networks.

  18. The Ex hoc Architecture

    DEFF Research Database (Denmark)

    2006-01-01

    Developed in the LIWAS project which develops technology for measuring road surfaces and communicating this data in an ad hoc environment. The communication part is built upon OOVM Resilient technology....

  19. Innovative research of AD HOC network mobility model

    Science.gov (United States)

    Chen, Xin

    2017-08-01

    It is difficult for researchers of AD HOC network to conduct actual deployment during experimental stage as the network topology is changeable and location of nodes is unfixed. Thus simulation still remains the main research method of the network. Mobility model is an important component of AD HOC network simulation. It is used to describe the movement pattern of nodes in AD HOC network (including location and velocity, etc.) and decides the movement trail of nodes, playing as the abstraction of the movement modes of nodes. Therefore, mobility model which simulates node movement is an important foundation for simulation research. In AD HOC network research, mobility model shall reflect the movement law of nodes as truly as possible. In this paper, node generally refers to the wireless equipment people carry. The main research contents include how nodes avoid obstacles during movement process and the impacts of obstacles on the mutual relation among nodes, based on which a Node Self Avoiding Obstacle, i.e. NASO model is established in AD HOC network.

  20. Decentralized session initiation protocol solution in ad hoc networks

    Science.gov (United States)

    Han, Lu; Jin, Zhigang; Shu, Yantai; Dong, Linfang

    2006-10-01

    With the fast development of ad hoc networks, SIP has attracted more and more attention in multimedia service. This paper proposes a new architecture to provide SIP service for ad hoc users, although there is no centralized SIP server deployed. In this solution, we provide the SIP service by the introduction of two nodes: Designated SIP Server (DS) and its Backup Server (BDS). The nodes of ad hoc network designate DS and BDS when they join the session nodes set and when some pre-defined events occur. A new sip message type called REGISTRAR is presented so nodes can send others REGISTRAR message to declare they want to be DS. According to the IP information taken in the message, an algorithm works like the election of DR and BDR in OSPF protocol is used to vote DS and BDS SIP servers. Naturally, the DS will be replaced by BDS when the DS is down for predicable or unpredictable reasons. To facilitate this, the DS should register to the BDS and transfer a backup of the SIP users' database. Considering the possibility DS or BDS may abruptly go down, a special policy is given. When there is no DS and BDS, a new election procedure is triggered just like the startup phase. The paper also describes how SIP works normally in the decentralized model as well as the evaluation of its performance. All sessions based on SIP in ad hoc such as DS voting have been tested in the real experiments within a 500m*500m square area where about 30 random nodes are placed.

  1. Post-hoc simulation study to adopt a computerized adaptive testing (CAT) for a Korean Medical License Examination.

    Science.gov (United States)

    Seo, Dong Gi; Choi, Jeongwook

    2018-05-17

    Computerized adaptive testing (CAT) has been adopted in license examinations due to a test efficiency and accuracy. Many research about CAT have been published to prove the efficiency and accuracy of measurement. This simulation study investigated scoring method and item selection methods to implement CAT in Korean medical license examination (KMLE). This study used post-hoc (real data) simulation design. The item bank used in this study was designed with all items in a 2017 KMLE. All CAT algorithms for this study were implemented by a 'catR' package in R program. In terms of accuracy, Rasch and 2parametric logistic (PL) model performed better than 3PL model. Modal a Posteriori (MAP) or Expected a Posterior (EAP) provided more accurate estimates than MLE and WLE. Furthermore Maximum posterior weighted information (MPWI) or Minimum expected posterior variance (MEPV) performed better than other item selection methods. In terms of efficiency, Rasch model was recommended to reduce test length. Simulation study should be performed under varied test conditions before adopting a live CAT. Based on a simulation study, specific scoring and item selection methods should be predetermined before implementing a live CAT.

  2. FRAMEWORK FOR AD HOC NETWORK COMMUNICATION IN MULTI-ROBOT SYSTEMS

    Directory of Open Access Journals (Sweden)

    Khilda Slyusar

    2016-11-01

    Full Text Available Assume a team of mobile robots operating in environments where no communication infrastructure like routers or access points is available. The robots have to create a mobile ad hoc network, in that case, it provides communication on peer-to-peer basis. The paper gives an overview of existing solutions how to route messages in such ad hoc networks between robots that are not directly connected and introduces a design of a software framework for realization of such communication. Feasibility of the proposed framework is shown on the example of distributed multi-robot exploration of an a priori unknown environment. Testing of developed functionality in an exploration scenario is based on results of several experiments with various input conditions of the exploration process and various sizes of a team and is described herein.

  3. Broadcast design in cognitive radio ad hoc networks

    CERN Document Server

    Song, Yi

    2014-01-01

    This SpringerBrief investigates the special challenges of broadcast design in cognitive radio (CR) ad hoc networks. It introduces two broadcast protocols in CR ad hoc networks: a quality-of-service based broadcast protocol under blind information and a fully-distributed broadcast protocol with collision avoidance. A novel unified analytical model is also presented to analyze the performance of the broadcast protocols. This is the first book dedicated to the unique broadcast design challenges in CR ad hoc networks. The authors also discuss the recent research on the performance analysis of broa

  4. Collaboration Layer for Robots in Mobile Ad-hoc Networks

    DEFF Research Database (Denmark)

    Borch, Ole; Madsen, Per Printz; Broberg, Jacob Honor´e

    2009-01-01

    In many applications multiple robots in Mobile Ad-hoc Networks are required to collaborate in order to solve a task. This paper shows by proof of concept that a Collaboration Layer can be modelled and designed to handle the collaborative communication, which enables robots in small to medium size...

  5. Mitigate DoS and DDoS attacks in Mobile Ad Hoc Networks

    DEFF Research Database (Denmark)

    Michalas, Antonis; Komninos, Nikos; Prasad, Neeli R.

    2011-01-01

    This paper proposes a technique to defeat Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks in Ad Hoc Networks. The technique is divided into two main parts and with game theory and cryptographic puzzles. Introduced first is a new client puzzle to prevent DoS attacks...... in DoS and DDoS attacks. Experimental results show the effectiveness of the approach for devices with limited resources and for environments like ad hoc networks where nodes must exchange information quickly....

  6. Ad hoc Sensor Networks to Support Maritime Interdiction Operations

    OpenAIRE

    Osmundson, John; Bordetsky, Alex

    2014-01-01

    Networking sensors, decision centers, and boarding parties supports success in Maritime Interdiction Operations. Led by a team from Naval Post-graduate School (NPS), experiments were conducted in 2012 to test the use of ad-hoc, self-forming communication networks to link sensors, people, and decision centers. The experiments involved international participants and successfully shared valuable biometric and radiological sensor data between boarding parties and decis...

  7. Conflict Management in "Ad Hoc" Problem-Solving Groups: A Preliminary Investigation.

    Science.gov (United States)

    Wallace, Les; Baxter, Leslie

    Full study of small group communication must include consideration of task and socio-emotional dimensions, especially in relation to group problem solving. Thirty small groups were tested for their reactions in various "ad hoc" conflict resolution situations. Instructions to the groups were (1) no problem-solving instructions (control),…

  8. Decentralized position verification in geographic ad hoc routing

    NARCIS (Netherlands)

    Leinmüller, Tim; Schoch, Elmar; Kargl, Frank; Maihöfer, Christian

    Inter-vehicle communication is regarded as one of the major applications of mobile ad hoc networks (MANETs). Compared to MANETs or wireless sensor networks (WSNs), these so-called vehicular ad hoc networks (VANETs) have unique requirements on network protocols. The requirements result mainly from

  9. Maximization of Energy Efficiency in Wireless ad hoc and Sensor Networks With SERENA

    Directory of Open Access Journals (Sweden)

    Saoucene Mahfoudh

    2009-01-01

    Full Text Available In wireless ad hoc and sensor networks, an analysis of the node energy consumption distribution shows that the largest part is due to the time spent in the idle state. This result is at the origin of SERENA, an algorithm to SchEdule RoutEr Nodes Activity. SERENA allows router nodes to sleep, while ensuring end-to-end communication in the wireless network. It is a localized and decentralized algorithm assigning time slots to nodes. Any node stays awake only during its slot and the slots assigned to its neighbors, it sleeps the remaining time. Simulation results show that SERENA enables us to maximize network lifetime while increasing the number of user messages delivered. SERENA is based on a two-hop coloring algorithm, whose complexity in terms of colors and rounds is evaluated. We then quantify the slot reuse. Finally, we show how SERENA improves the node energy consumption distribution and maximizes the energy efficiency of wireless ad hoc and sensor networks. We compare SERENA with classical TDMA and optimized variants such as USAP in wireless ad hoc and sensor networks.

  10. Ad hoc mobile wireless networks principles, protocols and applications

    CERN Document Server

    Sarkar, Subir Kumar; Puttamadappa, C

    2007-01-01

    Ad hoc mobile wireless networks have seen increased adaptation in a variety of disciplines because they can be deployed with simple infrastructures and virtually no central administration. In particular, the development of ad hoc wireless and sensor networks provides tremendous opportunities in areas including disaster recovery, defense, health care, and industrial environments. Ad Hoc Mobile Wireless Networks: Principles, Protocols and Applications explains the concepts, mechanisms, design, and performance of these systems. It presents in-depth explanations of the latest wireless technologies

  11. Ad hoc mobile wireless networks principles, protocols, and applications

    CERN Document Server

    Sarkar, Subir Kumar

    2013-01-01

    The military, the research community, emergency services, and industrial environments all rely on ad hoc mobile wireless networks because of their simple infrastructure and minimal central administration. Now in its second edition, Ad Hoc Mobile Wireless Networks: Principles, Protocols, and Applications explains the concepts, mechanism, design, and performance of these highly valued systems. Following an overview of wireless network fundamentals, the book explores MAC layer, routing, multicast, and transport layer protocols for ad hoc mobile wireless networks. Next, it examines quality of serv

  12. MAC Protocol for Ad Hoc Networks Using a Genetic Algorithm

    Science.gov (United States)

    Elizarraras, Omar; Panduro, Marco; Méndez, Aldo L.

    2014-01-01

    The problem of obtaining the transmission rate in an ad hoc network consists in adjusting the power of each node to ensure the signal to interference ratio (SIR) and the energy required to transmit from one node to another is obtained at the same time. Therefore, an optimal transmission rate for each node in a medium access control (MAC) protocol based on CSMA-CDMA (carrier sense multiple access-code division multiple access) for ad hoc networks can be obtained using evolutionary optimization. This work proposes a genetic algorithm for the transmission rate election considering a perfect power control, and our proposition achieves improvement of 10% compared with the scheme that handles the handshaking phase to adjust the transmission rate. Furthermore, this paper proposes a genetic algorithm that solves the problem of power combining, interference, data rate, and energy ensuring the signal to interference ratio in an ad hoc network. The result of the proposed genetic algorithm has a better performance (15%) compared to the CSMA-CDMA protocol without optimizing. Therefore, we show by simulation the effectiveness of the proposed protocol in terms of the throughput. PMID:25140339

  13. MAC Protocol for Ad Hoc Networks Using a Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Omar Elizarraras

    2014-01-01

    Full Text Available The problem of obtaining the transmission rate in an ad hoc network consists in adjusting the power of each node to ensure the signal to interference ratio (SIR and the energy required to transmit from one node to another is obtained at the same time. Therefore, an optimal transmission rate for each node in a medium access control (MAC protocol based on CSMA-CDMA (carrier sense multiple access-code division multiple access for ad hoc networks can be obtained using evolutionary optimization. This work proposes a genetic algorithm for the transmission rate election considering a perfect power control, and our proposition achieves improvement of 10% compared with the scheme that handles the handshaking phase to adjust the transmission rate. Furthermore, this paper proposes a genetic algorithm that solves the problem of power combining, interference, data rate, and energy ensuring the signal to interference ratio in an ad hoc network. The result of the proposed genetic algorithm has a better performance (15% compared to the CSMA-CDMA protocol without optimizing. Therefore, we show by simulation the effectiveness of the proposed protocol in terms of the throughput.

  14. Enhanced WWTP effluent organic matter removal in hybrid ozonation-coagulation (HOC) process catalyzed by Al-based coagulant

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Xin [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an, Shaanxi Province, 710055 (China); Jin, Pengkang, E-mail: pkjin@hotmail.com [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an, Shaanxi Province, 710055 (China); Hou, Rui [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an, Shaanxi Province, 710055 (China); Yang, Lei [Department of Materials Science and Engineering, Monash University, Clayton, VIC, 3800 (Australia); Wang, Xiaochang C., E-mail: xcwang@xauat.edu.cn [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an, Shaanxi Province, 710055 (China)

    2017-04-05

    Highlights: • A novel HOC process was firstly put forward to apply in wastewater reclamation. • Interactions between ozone and Al-based coagulants was found in the HOC process. • Ozonation can be catalyzed and enhanced by Al-based coagulants in the HOC process. • HOC process showed better organics removal than pre-ozonation-coagulation process. - Abstract: A novel hybrid ozonation-coagulation (HOC) process was developed for application in wastewater reclamation. In this process, ozonation and coagulation occurred simultaneously within a single unit. Compared with the conventional pre-ozonation-coagulation process, the HOC process exhibited much better performance in removing dissolved organic matters. In particular, the maximal organic matters removal efficiency was obtained at the ozone dosage of 1 mgO{sub 3}/mg DOC at each pH value (pH 5, 7 and 9). In order to interpret the mechanism of the HOC process, ozone decomposition was monitored. The results indicated that ozone decomposed much faster in the HOC process. Moreover, by using the reagent of O{sub 3}-resistant hydroxyl radical (·OH) probe compound, para-chlorobenzoic acid (pCBA), and electron paramagnetic resonance (EPR) analysis, it was observed that the HOC process generated higher content of ·OH compared with pre-ozonation process. This indicates that the ·OH oxidation reaction as the key step can be catalyzed and enhanced by Al-based coagulants and their hydrolyzed products in this developed process. Thus, based on the catalytic effects of Al-based coagulants on ozonation, the HOC process provides a promising alternative to the conventional technology for wastewater reclamation in terms of higher efficiency.

  15. Analysis of Pervasive Mobile Ad Hoc Routing Protocols

    Science.gov (United States)

    Qadri, Nadia N.; Liotta, Antonio

    Mobile ad hoc networks (MANETs) are a fundamental element of pervasive networks and therefore, of pervasive systems that truly support pervasive computing, where user can communicate anywhere, anytime and on-the-fly. In fact, future advances in pervasive computing rely on advancements in mobile communication, which includes both infrastructure-based wireless networks and non-infrastructure-based MANETs. MANETs introduce a new communication paradigm, which does not require a fixed infrastructure - they rely on wireless terminals for routing and transport services. Due to highly dynamic topology, absence of established infrastructure for centralized administration, bandwidth constrained wireless links, and limited resources in MANETs, it is challenging to design an efficient and reliable routing protocol. This chapter reviews the key studies carried out so far on the performance of mobile ad hoc routing protocols. We discuss performance issues and metrics required for the evaluation of ad hoc routing protocols. This leads to a survey of existing work, which captures the performance of ad hoc routing algorithms and their behaviour from different perspectives and highlights avenues for future research.

  16. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks.

    Science.gov (United States)

    Mezher, Ahmad Mohamad; Igartua, Mónica Aguilar; de la Cruz Llopis, Luis J; Pallarès Segarra, Esteve; Tripp-Barba, Carolina; Urquiza-Aguiar, Luis; Forné, Jordi; Sanvicente Gargallo, Emilio

    2015-04-17

    The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc.) could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers) rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs) has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic. Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs.

  17. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Ahmad Mohamad Mezher

    2015-04-01

    Full Text Available The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc. could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic. Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs.

  18. A-priori and post-hoc segmentation in the design of healthy eating campaigns

    DEFF Research Database (Denmark)

    Kazbare, Laura; van Trijp, Hans C. M.; Eskildsen, Jacob Kjær

    2010-01-01

    . Although such practice may be justifiable from the practical point of view, it is unclear how effective these implicit segmentations are. In this study the authors argue that  it is important to transcend demographic boundaries and to further segment demographic groups. A study with 13-15-year-old...... and a post-hoc segmentation. The results of the study show that it is useful and also ethical to differentiate people using segmentation methods, since it facilitates reaching more vulnerable segments of society that in general resist change. It also demonstrates that post-hoc segmentation is more helpful...

  19. Cross-Layer Design Approach for Power Control in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    A. Sarfaraz Ahmed

    2015-03-01

    Full Text Available In mobile ad hoc networks, communication among mobile nodes occurs through wireless medium The design of ad hoc network protocol, generally based on a traditional “layered approach”, has been found ineffective to deal with receiving signal strength (RSS-related problems, affecting the physical layer, the network layer and transport layer. This paper proposes a design approach, deviating from the traditional network design, toward enhancing the cross-layer interaction among different layers, namely physical, MAC and network. The Cross-Layer design approach for Power control (CLPC would help to enhance the transmission power by averaging the RSS values and to find an effective route between the source and the destination. This cross-layer design approach was tested by simulation (NS2 simulator and its performance over AODV was found to be better.

  20. Power control algorithms for mobile ad hoc networks

    Directory of Open Access Journals (Sweden)

    Nuraj L. Pradhan

    2011-07-01

    We will also focus on an adaptive distributed power management (DISPOW algorithm as an example of the multi-parameter optimization approach which manages the transmit power of nodes in a wireless ad hoc network to preserve network connectivity and cooperatively reduce interference. We will show that the algorithm in a distributed manner builds a unique stable network topology tailored to its surrounding node density and propagation environment over random topologies in a dynamic mobile wireless channel.

  1. UMDR: Multi-Path Routing Protocol for Underwater Ad Hoc Networks with Directional Antenna

    Science.gov (United States)

    Yang, Jianmin; Liu, Songzuo; Liu, Qipei; Qiao, Gang

    2018-01-01

    This paper presents a new routing scheme for underwater ad hoc networks based on directional antennas. Ad hoc networks with directional antennas have become a hot research topic because of space reuse may increase networks capacity. At present, researchers have applied traditional self-organizing routing protocols (such as DSR, AODV) [1] [2] on this type of networks, and the routing scheme is based on the shortest path metric. However, such routing schemes often suffer from long transmission delays and frequent link fragmentation along the intermediate nodes of the selected route. This is caused by a unique feature of directional transmission, often called as “deafness”. In this paper, we take a different approach to explore the advantages of space reuse through multipath routing. This paper introduces the validity of the conventional routing scheme in underwater ad hoc networks with directional antennas, and presents a special design of multipath routing algorithm for directional transmission. The experimental results show a significant performance improvement in throughput and latency.

  2. Post-hoc pattern-oriented testing and tuning of an existing large model: lessons from the field vole.

    Directory of Open Access Journals (Sweden)

    Christopher J Topping

    Full Text Available Pattern-oriented modeling (POM is a general strategy for modeling complex systems. In POM, multiple patterns observed at different scales and hierarchical levels are used to optimize model structure, to test and select sub-models of key processes, and for calibration. So far, POM has been used for developing new models and for models of low to moderate complexity. It remains unclear, though, whether the basic idea of POM to utilize multiple patterns, could also be used to test and possibly develop existing and established models of high complexity. Here, we use POM to test, calibrate, and further develop an existing agent-based model of the field vole (Microtus agrestis, which was developed and tested within the ALMaSS framework. This framework is complex because it includes a high-resolution representation of the landscape and its dynamics, of the individual's behavior, and of the interaction between landscape and individual behavior. Results of fitting to the range of patterns chosen were generally very good, but the procedure required to achieve this was long and complicated. To obtain good correspondence between model and the real world it was often necessary to model the real world environment closely. We therefore conclude that post-hoc POM is a useful and viable way to test a highly complex simulation model, but also warn against the dangers of over-fitting to real world patterns that lack details in their explanatory driving factors. To overcome some of these obstacles we suggest the adoption of open-science and open-source approaches to ecological simulation modeling.

  3. agradecimento aos consultores ad hoc

    Directory of Open Access Journals (Sweden)

    REA Editor

    2012-02-01

    Full Text Available Agradecemos aos professores Nildo Viana (UFG e Flavio Sofiati (UFG, organizadores do DOSSIÊ JUVENTUDE & SOCIEDADE, e aos Consultores Ad hoc pela leitura e apreciação crítica dos artigos submetidos e publicados nesta edição.

  4. Ad hoc networks telecommunications and game theory

    CERN Document Server

    Benslama, Malek; Batatia, Hadj

    2015-01-01

    Random SALOHA and CSMA protocols that are used to access MAC in ad hoc networks are very small compared to the multiple and spontaneous use of the transmission channel. So they have low immunity to the problems of packet collisions. Indeed, the transmission time is the critical factor in the operation of such networks. The simulations demonstrate the positive impact of erasure codes on the throughput of the transmission in ad hoc networks. However, the network still suffers from the intermittency and volatility of its efficiency throughout its operation, and it switches quickly to the satura

  5. Vehicular ad hoc network security and privacy

    CERN Document Server

    Lin, X

    2015-01-01

    Unlike any other book in this area, this book provides innovative solutions to security issues, making this book a must read for anyone working with or studying security measures. Vehicular Ad Hoc Network Security and Privacy mainly focuses on security and privacy issues related to vehicular communication systems. It begins with a comprehensive introduction to vehicular ad hoc network and its unique security threats and privacy concerns and then illustrates how to address those challenges in highly dynamic and large size wireless network environments from multiple perspectives. This book is richly illustrated with detailed designs and results for approaching security and privacy threats.

  6. Optimal channel choice for collaborative ad-hoc dissemination

    DEFF Research Database (Denmark)

    Hu, Liang; Boudec, J-Y. L.; Vojnovic, M.

    2010-01-01

    Collaborative ad-hoc dissemination of information has been proposed as an efficient means to disseminate information among devices in a wireless ad-hoc network. Devices help in forwarding the information channels to the entire network, by disseminating the channels they subscribe to, plus others...... by a Metropolis-Hastings sampling algorithm. We also give a variant that accounts for battery level. This leads to a practical channel selection and re-selection algorithm that can be implemented without any central control....

  7. A fault-tolerant small world topology control model in ad hoc networks for search and rescue

    Science.gov (United States)

    Tan, Mian; Fang, Ling; Wu, Yue; Zhang, Bo; Chang, Bowen; Holme, Petter; Zhao, Jing

    2018-02-01

    Due to their self-organized, multi-hop and distributed characteristics, ad hoc networks are useful in search and rescue. Topology control models need to be designed for energy-efficient, robust and fast communication in ad hoc networks. This paper proposes a topology control model which specializes for search and rescue-Compensation Small World-Repeated Game (CSWRG)-which integrates mobility models, constructing small world networks and a game-theoretic approach to the allocation of resources. Simulation results show that our mobility models can enhance the communication performance of the constructed small-world networks. Our strategy, based on repeated game, can suppress selfish behavior and compensate agents that encounter selfish or faulty neighbors. This model could be useful for the design of ad hoc communication networks.

  8. Les Protocoles de routage dans les réseaux mobiles Ad Hoc ...

    African Journals Online (AJOL)

    Dans cet article nous présentons un état de l'art sur les protocoles de routage dans les réseaux mobiles Ad hoc. Mots clés : Réseaux mobiles ad hoc/, Protocoles de routage. Routing protocols in wireless mobile ad hoc networks. Abstract:The communication between users with handheld computers interconnected through ...

  9. Improving VANETs Connectivity with a Totally Ad Hoc Living Mobile Backbone

    Directory of Open Access Journals (Sweden)

    Joilson Alves Junior

    2015-01-01

    Full Text Available The vehicular ad hoc network (VANET for intelligent transportation systems is an emerging concept to improve transportation security, reliability, and management. The network behavior can be totally different in topological aspects because of the mobility of vehicular nodes. The topology can be fully connected when the flow of vehicles is high and may have low connectivity or be invalid when the flow of vehicles is low or unbalanced. In big cities, the metropolitan buses that travel on exclusive lanes may be used to set up a metropolitan vehicular data network (backbone, raising the connectivity among the vehicles. Therefore, this paper proposes the implementation of a living mobile backbone, totally ad hoc (MOB-NET, which will provide infrastructure and raise the network connectivity. In order to show the viability of MOB-NET, statistical analyses were made with real data of express buses that travel through exclusive lanes, besides evaluations through simulations and analytic models. The statistic, analytic, and simulation results prove that the buses that travel through exclusive lanes can be used to build a communication network totally ad hoc and provide connectivity in more than 99% of the time, besides raising the delivery rate up to 95%.

  10. Research on Propagation Model of Malicious Programs in Ad Hoc Wireless Network

    Directory of Open Access Journals (Sweden)

    Weimin GAO

    2014-01-01

    Full Text Available Ad Hoc wireless network faces more security threats than traditional network due to its P2P system structure and the limited node resources. In recent years, malicious program has become one of the most important researches on international network security and information security. The research of malicious programs on wireless network has become a new research hotspot in the field of malicious programs. This paper first analyzed the Ad Hoc network system structure, security threats, the common classification of malicious programs and the bionic propagation model. Then starting from the differential equations of the SEIR virus propagation model, the question caused by introducing the SEIR virus propagation model in Ad Hoc wireless network was analyzed. This paper improved the malicious program propagation model through introducing the network topology features and concepts such as immunization delay, and designed an improved algorithm combined with the dynamic evolution of malware propagation process. Considering of the network virus propagation characteristics, network characteristics and immunization strategy to improve simulation model experiment analysis, the experimental results show that both the immunization strategy and the degrees of node can affect the propagation of malicious program.

  11. Auto-Configuration Protocols in Mobile Ad Hoc Networks

    Science.gov (United States)

    Villalba, Luis Javier García; Matesanz, Julián García; Orozco, Ana Lucila Sandoval; Díaz, José Duván Márquez

    2011-01-01

    The TCP/IP protocol allows the different nodes in a network to communicate by associating a different IP address to each node. In wired or wireless networks with infrastructure, we have a server or node acting as such which correctly assigns IP addresses, but in mobile ad hoc networks there is no such centralized entity capable of carrying out this function. Therefore, a protocol is needed to perform the network configuration automatically and in a dynamic way, which will use all nodes in the network (or part thereof) as if they were servers that manage IP addresses. This article reviews the major proposed auto-configuration protocols for mobile ad hoc networks, with particular emphasis on one of the most recent: D2HCP. This work also includes a comparison of auto-configuration protocols for mobile ad hoc networks by specifying the most relevant metrics, such as a guarantee of uniqueness, overhead, latency, dependency on the routing protocol and uniformity. PMID:22163814

  12. Auto-configuration protocols in mobile ad hoc networks.

    Science.gov (United States)

    Villalba, Luis Javier García; Matesanz, Julián García; Orozco, Ana Lucila Sandoval; Díaz, José Duván Márquez

    2011-01-01

    The TCP/IP protocol allows the different nodes in a network to communicate by associating a different IP address to each node. In wired or wireless networks with infrastructure, we have a server or node acting as such which correctly assigns IP addresses, but in mobile ad hoc networks there is no such centralized entity capable of carrying out this function. Therefore, a protocol is needed to perform the network configuration automatically and in a dynamic way, which will use all nodes in the network (or part thereof) as if they were servers that manage IP addresses. This article reviews the major proposed auto-configuration protocols for mobile ad hoc networks, with particular emphasis on one of the most recent: D2HCP. This work also includes a comparison of auto-configuration protocols for mobile ad hoc networks by specifying the most relevant metrics, such as a guarantee of uniqueness, overhead, latency, dependency on the routing protocol and uniformity.

  13. QoS Routing in Ad-Hoc Networks Using GA and Multi-Objective Optimization

    Directory of Open Access Journals (Sweden)

    Admir Barolli

    2011-01-01

    Full Text Available Much work has been done on routing in Ad-hoc networks, but the proposed routing solutions only deal with the best effort data traffic. Connections with Quality of Service (QoS requirements, such as voice channels with delay and bandwidth constraints, are not supported. The QoS routing has been receiving increasingly intensive attention, but searching for the shortest path with many metrics is an NP-complete problem. For this reason, approximated solutions and heuristic algorithms should be developed for multi-path constraints QoS routing. Also, the routing methods should be adaptive, flexible, and intelligent. In this paper, we use Genetic Algorithms (GAs and multi-objective optimization for QoS routing in Ad-hoc Networks. In order to reduce the search space of GA, we implemented a search space reduction algorithm, which reduces the search space for GAMAN (GA-based routing algorithm for Mobile Ad-hoc Networks to find a new route. We evaluate the performance of GAMAN by computer simulations and show that GAMAN has better behaviour than GLBR (Genetic Load Balancing Routing.

  14. SURVEI TEKNIK CLUSTERING ROUTING BERDASARKAN MOBILITAS PADA WIRELESS AD-HOC NETWORK

    Directory of Open Access Journals (Sweden)

    I Nyoman Trisna Wirawan

    2016-01-01

    Full Text Available Wireless ad-hoc merupakan sebuah skema jaringan yang didesain supaya mampu beroperasi tanpa membutuhkan infrastruktur tetap serta bersifat otonom. Teknik flooding pada proses path discovery dalam kasus wireless ad-hoc network dapat menimbulkan masalah beban jaringan yang berlebihan. Oleh karena itu, sebuah skema clustering diusulkan untuk mengurangi adanya flooding paket yang berlebihan dengan membagi node-node dalam jaringan menjadi beberapa bagian berdasarkan parameter tertentu. Teknik ini efektifuntuk mengurangi paket yang harus dilewatkan dalam jaringan. Namun masalah muncul ketika sebuah jaringan wireless ad-hoc harus membentuk sebuah cluster dengan mempertimbangkan beberapa parameter khusus. Parameter tersebut harus disesuaikan dengan kasus yang dihadapi. Pada tulisan ini akan dibahas secara khusus mengenai penerapan skema clustering dalam lingkungan wireless ad-hoc network, baik pada MANETdan penyesuaian skema clustering yang harus dilakukan pada VANET berdasarkan mobilitasnya.

  15. Effects of Data Replication on Data Exfiltration in Mobile Ad Hoc Networks Utilizing Reactive Protocols

    Science.gov (United States)

    2015-03-01

    aerial vehicle VANET vehicular ad hoc network VoIP Voice over Internet Protocol VRR Virtual Ring Routing xiii EFFECTS OF DATA REPLICATION ON DATA...ad hoc networks in mobile ad hoc networks (MANETs), vehicular ad hoc networks (VANETs), and flying ad hoc net- works (FANETs). Much of the research...metric, such as capacity, congestion , power, or combinations thereof. Caro refers to two different types of ants, FANTs and BANTs which are analogous to

  16. Distributed optimization of a multisubchannel Ad Hoc cognitive radio network

    KAUST Repository

    Leith, Alex

    2012-05-01

    In this paper, we study the distributed-duality-based optimization of a multisubchannel ad hoc cognitive radio network (CRN) that coexists with a multicell primary radio network (PRN). For radio resource allocation in multiuser orthogonal frequency-division multiplexing (MU-OFDM) systems, the orthogonal-access-based exclusive subchannel assignment (ESA) technique has been a popular method, but it is suboptimal in ad hoc networks, because nonorthogonal access between multiple secondary-user links by using shared subchannel assignment (SSA) can bring a higher weighted sum rate. We utilize the Lagrangian dual composition tool and design low-complexity near-optimal SSA resource allocation methods, assuming practical discrete-rate modulation and that the CRN-to-PRN interference constraint has to strictly be satisfied. However, available SSA methods for CRNs are either suboptimal or involve high complexity and suffer from slow convergence. To address this problem, we design fast-convergence SSA duality schemes and introduce several novel methods to increase the speed of convergence and to satisfy various system constraints with low complexity. For practical implementation in ad hoc CRNs, we design distributed-duality schemes that involve only a small number of CRN local information exchanges for dual update. The effects of many system parameters are presented through simulation results, which show that the near-optimal SSA duality scheme can perform significantly better than the suboptimal ESA duality and SSA-iterative waterfilling schemes and that the performance loss of the distributed schemes is small, compared with their centralized counterparts. © 2012 IEEE.

  17. Interference in wireless ad hoc networks with smart antennas

    KAUST Repository

    Alabdulmohsin, Ibrahim

    2014-08-01

    In this paper, we show that the use of directional antennas in wireless ad hoc networks can actually increase interference due to limitations of virtual carrier sensing. We derive a simple mathematical expression for interference in both physical and virtual carrier sense networks, which reveals counter-intuitively that receivers in large dense networks with directional antennas can experience larger interference than in omnidirectional networks unless the beamwidth is sufficiently small. Validity of mathematical analysis is confirmed using simulations.

  18. Sensor and ad-hoc networks theoretical and algorithmic aspects

    CERN Document Server

    Makki, S Kami; Pissinou, Niki; Makki, Shamila; Karimi, Masoumeh; Makki, Kia

    2008-01-01

    This book brings together leading researchers and developers in the field of wireless sensor networks to explain the special problems and challenges of the algorithmic aspects of sensor and ad-hoc networks. The book also fosters communication not only between the different sensor and ad-hoc communities, but also between those communities and the distributed systems and information systems communities. The topics addressed pertain to the sensors and mobile environment.

  19. Multichannel MAC Layer In Mobile Ad—Hoc Network

    Science.gov (United States)

    Logesh, K.; Rao, Samba Siva

    2010-11-01

    This paper we presented the design objectives and technical challenges in Multichannel MAC protocols in Mobile Ad-hoc Network. In IEEE 802.11 a/b/g standards allow use of multiple channels, only a single channel is popularly used, due to the lack of efficient protocols that enable use of Multiple Channels. Even though complex environments in ad hoc networks require a combined control of physical (PHY) and medium access control (MAC) layers resources in order to optimize performance. And also we discuss the characteristics of cross-layer frame and give a multichannel MAC approach.

  20. Does Ad Hoc Coronary Intervention Reduce Radiation Exposure? – Analysis of 568 Patients

    Energy Technology Data Exchange (ETDEWEB)

    Truffa, Márcio A. M., E-mail: marciotruffa@yahoo.com.br; Alves, Gustavo M.P.; Bernardi, Fernando; Esteves Filho, Antonio; Ribeiro, Expedito; Galon, Micheli Z.; Spadaro, André; Kajita, Luiz J.; Arrieta, Raul; Lemos, Pedro A. [Instituto do Coração - Hospital das Clínicas - Faculdade de Medicina da Universidade de São Paulo (USP), São Paulo, SP (Brazil)

    2015-11-15

    Advantages and disadvantages of ad hoc percutaneous coronary intervention have been described. However little is known about the radiation exposure of that procedure as compared with the staged intervention. To compare the radiation dose of the ad hoc percutaneous coronary intervention with that of the staged procedure The dose-area product and total Kerma were measured, and the doses of the diagnostic and therapeutic procedures were added. In addition, total fluoroscopic time and number of acquisitions were evaluated. A total of 568 consecutive patients were treated with ad hoc percutaneous coronary intervention (n = 320) or staged percutaneous coronary intervention (n = 248). On admission, the ad hoc group had less hypertension (74.1% vs 81.9%; p = 0.035), dyslipidemia (57.8% vs. 67.7%; p = 0.02) and three-vessel disease (38.8% vs. 50.4%; p = 0.015). The ad hoc group was exposed to significantly lower radiation doses, even after baseline characteristic adjustment between both groups. The ad hoc group was exposed to a total dose-area product of 119.7 ± 70.7 Gycm{sup 2}, while the staged group, to 139.2 ± 75.3 Gycm{sup 2} (p < 0.001). Ad hoc percutaneous coronary intervention reduced radiation exposure as compared with diagnostic and therapeutic procedures performed at two separate times.

  1. Does Ad Hoc Coronary Intervention Reduce Radiation Exposure? – Analysis of 568 Patients

    International Nuclear Information System (INIS)

    Truffa, Márcio A. M.; Alves, Gustavo M.P.; Bernardi, Fernando; Esteves Filho, Antonio; Ribeiro, Expedito; Galon, Micheli Z.; Spadaro, André; Kajita, Luiz J.; Arrieta, Raul; Lemos, Pedro A.

    2015-01-01

    Advantages and disadvantages of ad hoc percutaneous coronary intervention have been described. However little is known about the radiation exposure of that procedure as compared with the staged intervention. To compare the radiation dose of the ad hoc percutaneous coronary intervention with that of the staged procedure The dose-area product and total Kerma were measured, and the doses of the diagnostic and therapeutic procedures were added. In addition, total fluoroscopic time and number of acquisitions were evaluated. A total of 568 consecutive patients were treated with ad hoc percutaneous coronary intervention (n = 320) or staged percutaneous coronary intervention (n = 248). On admission, the ad hoc group had less hypertension (74.1% vs 81.9%; p = 0.035), dyslipidemia (57.8% vs. 67.7%; p = 0.02) and three-vessel disease (38.8% vs. 50.4%; p = 0.015). The ad hoc group was exposed to significantly lower radiation doses, even after baseline characteristic adjustment between both groups. The ad hoc group was exposed to a total dose-area product of 119.7 ± 70.7 Gycm 2 , while the staged group, to 139.2 ± 75.3 Gycm 2 (p < 0.001). Ad hoc percutaneous coronary intervention reduced radiation exposure as compared with diagnostic and therapeutic procedures performed at two separate times

  2. Securing DSR with mobile agents in wireless ad hoc networks

    Directory of Open Access Journals (Sweden)

    Ahmed Abosamra

    2011-03-01

    Full Text Available Ad hoc wireless network consists of a set of wireless nodes communicating with each other without a pre-defined infrastructure. They communicate by forwarding packets which can reach wireless nodes that do not exist in the range of the direct radio transmission. Designing ad hoc network routing protocols is a challenging task because of its decentralized infrastructure which makes securing ad hoc networks more and more challenging. Dynamic Source Routing (DSR protocol is a popular routing protocol designed for use in wireless ad hoc networks. Mobile agent is a promising technology used in diverse fields of network applications. In this paper, we try to implement DSR using mobile agents for securing this type of wireless network. Hybrid encryption technique (symmetric key encryption/public key encryption is used to improve performance; where symmetric keys are used to encrypt routing data to authenticate and authorize node sending data, while, public keys are used for the exchange of symmetric keys between nodes. We found that DSR may be secured using mobile agents with competitive performance.

  3. Model checking mobile ad hoc networks

    NARCIS (Netherlands)

    Ghassemi, Fatemeh; Fokkink, Wan

    2016-01-01

    Modeling arbitrary connectivity changes within mobile ad hoc networks (MANETs) makes application of automated formal verification challenging. We use constrained labeled transition systems as a semantic model to represent mobility. To model check MANET protocols with respect to the underlying

  4. MWAHCA: a multimedia wireless ad hoc cluster architecture.

    Science.gov (United States)

    Diaz, Juan R; Lloret, Jaime; Jimenez, Jose M; Sendra, Sandra

    2014-01-01

    Wireless Ad hoc networks provide a flexible and adaptable infrastructure to transport data over a great variety of environments. Recently, real-time audio and video data transmission has been increased due to the appearance of many multimedia applications. One of the major challenges is to ensure the quality of multimedia streams when they have passed through a wireless ad hoc network. It requires adapting the network architecture to the multimedia QoS requirements. In this paper we propose a new architecture to organize and manage cluster-based ad hoc networks in order to provide multimedia streams. Proposed architecture adapts the network wireless topology in order to improve the quality of audio and video transmissions. In order to achieve this goal, the architecture uses some information such as each node's capacity and the QoS parameters (bandwidth, delay, jitter, and packet loss). The architecture splits the network into clusters which are specialized in specific multimedia traffic. The real system performance study provided at the end of the paper will demonstrate the feasibility of the proposal.

  5. MWAHCA: A Multimedia Wireless Ad Hoc Cluster Architecture

    Directory of Open Access Journals (Sweden)

    Juan R. Diaz

    2014-01-01

    Full Text Available Wireless Ad hoc networks provide a flexible and adaptable infrastructure to transport data over a great variety of environments. Recently, real-time audio and video data transmission has been increased due to the appearance of many multimedia applications. One of the major challenges is to ensure the quality of multimedia streams when they have passed through a wireless ad hoc network. It requires adapting the network architecture to the multimedia QoS requirements. In this paper we propose a new architecture to organize and manage cluster-based ad hoc networks in order to provide multimedia streams. Proposed architecture adapts the network wireless topology in order to improve the quality of audio and video transmissions. In order to achieve this goal, the architecture uses some information such as each node’s capacity and the QoS parameters (bandwidth, delay, jitter, and packet loss. The architecture splits the network into clusters which are specialized in specific multimedia traffic. The real system performance study provided at the end of the paper will demonstrate the feasibility of the proposal.

  6. Algorithmic, LOCS and HOCS (chemistry) exam questions: performance and attitudes of college students

    Science.gov (United States)

    Zoller, Uri

    2002-02-01

    The performance of freshmen biology and physics-mathematics majors and chemistry majors as well as pre- and in-service chemistry teachers in two Israeli universities on algorithmic (ALG), lower-order cognitive skills (LOCS), and higher-order cognitive skills (HOCS) chemistry exam questions were studied. The driving force for the study was an interest in moving science and chemistry instruction from an algorithmic and factual recall orientation dominated by LOCS, to a decision-making, problem-solving and critical system thinking approach, dominated by HOCS. College students' responses to the specially designed ALG, LOCS and HOCS chemistry exam questions were scored and analysed for differences and correlation between the performance means within and across universities by the questions' category. This was followed by a combined student interview - 'speaking aloud' problem solving session for assessing the thinking processes involved in solving these types of questions and the students' attitudes towards them. The main findings were: (1) students in both universities performed consistently in each of the three categories in the order of ALG > LOCS > HOCS; their 'ideological' preference, was HOCS > algorithmic/LOCS, - referred to as 'computational questions', but their pragmatic preference was the reverse; (2) success on algorithmic/LOCS does not imply success on HOCS questions; algorithmic questions constitute a category on its own as far as students success in solving them is concerned. Our study and its results support the effort being made, worldwide, to integrate HOCS-fostering teaching and assessment strategies and, to develop HOCS-oriented science-technology-environment-society (STES)-type curricula within science and chemistry education.

  7. Ad-Hoc vs. Standardized and Optimized Arthropod Diversity Sampling

    Directory of Open Access Journals (Sweden)

    Pedro Cardoso

    2009-09-01

    Full Text Available The use of standardized and optimized protocols has been recently advocated for different arthropod taxa instead of ad-hoc sampling or sampling with protocols defined on a case-by-case basis. We present a comparison of both sampling approaches applied for spiders in a natural area of Portugal. Tests were made to their efficiency, over-collection of common species, singletons proportions, species abundance distributions, average specimen size, average taxonomic distinctness and behavior of richness estimators. The standardized protocol revealed three main advantages: (1 higher efficiency; (2 more reliable estimations of true richness; and (3 meaningful comparisons between undersampled areas.

  8. Internet-Based Mobile Ad Hoc Networking (Preprint)

    National Research Council Canada - National Science Library

    Corson, M. S; Macker, Joseph P; Cirincione, Gregory H

    1999-01-01

    Internet-based Mobile Ad Hoc Networking is an emerging technology that supports self-organizing, mobile networking infrastructures, and is one which appears well-suited for use in future commercial...

  9. Multiagent Based Information Dissemination in Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    S.S. Manvi

    2009-01-01

    Full Text Available Vehicular Ad hoc Networks (VANETs are a compelling application of ad hoc networks, because of the potential to access specific context information (e.g. traffic conditions, service updates, route planning and deliver multimedia services (Voice over IP, in-car entertainment, instant messaging, etc.. This paper proposes an agent based information dissemination model for VANETs. A two-tier agent architecture is employed comprising of the following: 1 'lightweight', network-facing, mobile agents; 2 'heavyweight', application-facing, norm-aware agents. The limitations of VANETs lead us to consider a hybrid wireless network architecture that includes Wireless LAN/Cellular and ad hoc networking for analyzing the proposed model. The proposed model provides flexibility, adaptability and maintainability for traffic information dissemination in VANETs as well as supports robust and agile network management. The proposed model has been simulated in various network scenarios to evaluate the effectiveness of the approach.

  10. A Spontaneous Ad Hoc Network to Share WWW Access

    Directory of Open Access Journals (Sweden)

    Lloret Jaime

    2010-01-01

    Full Text Available In this paper, we propose a secure spontaneous ad-hoc network, based on direct peer-to-peer interaction, to grant a quick, easy, and secure access to the users to surf the Web. The paper shows the description of our proposal, the procedure of the nodes involved in the system, the security algorithms implemented, and the designed messages. We have taken into account the security and its performance. Although some people have defined and described the main features of spontaneous ad-hoc networks, nobody has published any design and simulation until today. Spontaneous networking will enable a more natural form of wireless computing when people physically meet in the real world. We also validate the success of our proposal through several simulations and comparisons with a regular architecture, taking into account the optimization of the resources of the devices. Finally, we compare our proposal with other caching techniques published in the related literature. The proposal has been developed with the main objective of improving the communication and integration between different study centers of low-resource communities. That is, it lets communicate spontaneous networks, which are working collaboratively and which have been created on different physical places.

  11. DESAIN ALGORITMA DAN SIMULASI ROUTING UNTUK GATEWAY AD HOC WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    Nixson Meok

    2009-12-01

    Full Text Available   Routing protocol to the wireless ad hoc networks is very needed in the communication process between some terminals, to send the data packet through one or several node(s to the destination address where the network typology is always changing. Many previous works that discussed about routing ad hoc both for manet (mobile ad hoc networks and wireless networks, but the emphasis have more focus on comparing the performance of several routing ad hoc. While in this work, there is a bulding of routing algorithm model to gateway in land to the nodes that analogized as a boat that move on the sea. With the assumption that the communication inter terminals to radio band of Very High Frequency, thus algorithm that built in the simulation based on the range gap of the HF frequency. The result of this simulation will be developed as the platform to implement the service development of multiuser communication

  12. Estudio de la topología y protocolos de una red móvil ad-hoc

    OpenAIRE

    Albalat Montenegro, Bruno

    2010-01-01

    This project intends to describe how a basic messaging application that, using ad-hoc networks, supports delay tolerance, has been created. Its purpose is to serve as a basis for research groups to be able to work over it for their testing purposes.

  13. Quantum load balancing in ad hoc networks

    Science.gov (United States)

    Hasanpour, M.; Shariat, S.; Barnaghi, P.; Hoseinitabatabaei, S. A.; Vahid, S.; Tafazolli, R.

    2017-06-01

    This paper presents a novel approach in targeting load balancing in ad hoc networks utilizing the properties of quantum game theory. This approach benefits from the instantaneous and information-less capability of entangled particles to synchronize the load balancing strategies in ad hoc networks. The quantum load balancing (QLB) algorithm proposed by this work is implemented on top of OLSR as the baseline routing protocol; its performance is analyzed against the baseline OLSR, and considerable gain is reported regarding some of the main QoS metrics such as delay and jitter. Furthermore, it is shown that QLB algorithm supports a solid stability gain in terms of throughput which stands a proof of concept for the load balancing properties of the proposed theory.

  14. Recent development in wireless sensor and ad-hoc networks

    CERN Document Server

    Li, Xiaolong; Yang, Yeon-Mo

    2015-01-01

    Wireless Sensor Network (WSN) consists of numerous physically distributed autonomous devices used for sensing and monitoring the physical and/or environmental conditions. A WSN uses a gateway that provides wireless connectivity to the wired world as well as distributed networks. There are many open problems related to Ad-Hoc networks and its applications. Looking at the expansion of the cellular infrastructure, Ad-Hoc network may be acting as the basis of the 4th generation wireless technology with the new paradigm of ‘anytime, anywhere communications’. To realize this, the real challenge would be the security, authorization and management issues of the large scale WSNs. This book is an edited volume in the broad area of WSNs. The book covers various chapters like Multi-Channel Wireless Sensor Networks, its Coverage, Connectivity as well as Deployment. It covers comparison of various communication protocols and algorithms such as MANNET, ODMRP and ADMR Protocols for Ad hoc Multicasting, Location Based C...

  15. Intelligent routing protocol for ad hoc wireless network

    Science.gov (United States)

    Peng, Chaorong; Chen, Chang Wen

    2006-05-01

    A novel routing scheme for mobile ad hoc networks (MANETs), which combines hybrid and multi-inter-routing path properties with a distributed topology discovery route mechanism using control agents is proposed in this paper. In recent years, a variety of hybrid routing protocols for Mobile Ad hoc wireless networks (MANETs) have been developed. Which is proactively maintains routing information for a local neighborhood, while reactively acquiring routes to destinations beyond the global. The hybrid protocol reduces routing discovery latency and the end-to-end delay by providing high connectivity without requiring much of the scarce network capacity. On the other side the hybrid routing protocols in MANETs likes Zone Routing Protocol still need route "re-discover" time when a route between zones link break. Sine the topology update information needs to be broadcast routing request on local zone. Due to this delay, the routing protocol may not be applicable for real-time data and multimedia communication. We utilize the advantages of a clustering organization and multi-routing path in routing protocol to achieve several goals at the same time. Firstly, IRP efficiently saves network bandwidth and reduces route reconstruction time when a routing path fails. The IRP protocol does not require global periodic routing advertisements, local control agents will automatically monitor and repair broke links. Secondly, it efficiently reduces congestion and traffic "bottlenecks" for ClusterHeads in clustering network. Thirdly, it reduces significant overheads associated with maintaining clusters. Fourthly, it improves clusters stability due to dynamic topology changing frequently. In this paper, we present the Intelligent Routing Protocol. First, we discuss the problem of routing in ad hoc networks and the motivation of IRP. We describe the hierarchical architecture of IRP. We describe the routing process and illustrate it with an example. Further, we describe the control manage

  16. Energy-Aware Routing Protocol for Ad Hoc Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mann Raminder P

    2005-01-01

    Full Text Available Wireless ad hoc sensor networks differ from wireless ad hoc networks from the following perspectives: low energy, lightweight routing protocols, and adaptive communication patterns. This paper proposes an energy-aware routing protocol (EARP suitable for ad hoc wireless sensor networks and presents an analysis for its energy consumption in various phases of route discovery and maintenance. Based on the energy consumption associated with route request processing, EARP advocates the minimization of route requests by allocating dynamic route expiry times. This paper introduces a unique mechanism for estimation of route expiry time based on the probability of route validity, which is a function of time, number of hops, and mobility parameters. In contrast to AODV, EARP reduces the repeated flooding of route requests by maintaining valid routes for longer durations.

  17. Supporting Dynamic Ad hoc Collaboration Capabilities

    CERN Document Server

    Agarwal, D

    2003-01-01

    Modern HENP experiments such as CMS and Atlas involve as many as 2000 collaborators around the world. Collaborations this large will be unable to meet often enough to support working closely together. Many of the tools currently available for collaboration focus on heavy-weight applications such as videoconferencing tools. While these are important, there is a more basic need for tools that support connecting physicists to work together on an ad hoc or continuous basis. Tools that support the day-to-day connectivity and underlying needs of a group of collaborators are important for providing light-weight, non-intrusive, and flexible ways to work collaboratively. Some example tools include messaging, file-sharing, and shared plot viewers. An important component of the environment is a scalable underlying communication framework. In this paper we will describe our current progress on building a dynamic and ad hoc collaboration environment and our vision for its evolution into a HENP collaboration environment.

  18. Supporting Dynamic Ad hoc Collaboration Capabilities

    International Nuclear Information System (INIS)

    Agarwal, Deborah A.; Berket, Karlo

    2003-01-01

    Modern HENP experiments such as CMS and Atlas involve as many as 2000 collaborators around the world. Collaborations this large will be unable to meet often enough to support working closely together. Many of the tools currently available for collaboration focus on heavy-weight applications such as videoconferencing tools. While these are important, there is a more basic need for tools that support connecting physicists to work together on an ad hoc or continuous basis. Tools that support the day-to-day connectivity and underlying needs of a group of collaborators are important for providing light-weight, non-intrusive, and flexible ways to work collaboratively. Some example tools include messaging, file-sharing, and shared plot viewers. An important component of the environment is a scalable underlying communication framework. In this paper we will describe our current progress on building a dynamic and ad hoc collaboration environment and our vision for its evolution into a HENP collaboration environment

  19. Twenty-One at TREC-7: ad-hoc and cross-language track

    NARCIS (Netherlands)

    Hiemstra, Djoerd; Kraaij, Wessel; Voorhees, E.M; Harman, D.K.

    1999-01-01

    This paper describes the official runs of the Twenty-One group for TREC-7. The Twenty-One group participated in the ad-hoc and the cross-language track and made the following accomplishments: We developed a new weighting algorithm, which outperforms the popular Cornell version of BM25 on the ad-hoc

  20. Power-Aware Intrusion Detection in Mobile Ad Hoc Networks

    Science.gov (United States)

    Şen, Sevil; Clark, John A.; Tapiador, Juan E.

    Mobile ad hoc networks (MANETs) are a highly promising new form of networking. However they are more vulnerable to attacks than wired networks. In addition, conventional intrusion detection systems (IDS) are ineffective and inefficient for highly dynamic and resource-constrained environments. Achieving an effective operational MANET requires tradeoffs to be made between functional and non-functional criteria. In this paper we show how Genetic Programming (GP) together with a Multi-Objective Evolutionary Algorithm (MOEA) can be used to synthesise intrusion detection programs that make optimal tradeoffs between security criteria and the power they consume.

  1. On Throughput Improvement of Wireless Ad Hoc Networks with Hidden Nodes

    Science.gov (United States)

    Choi, Hong-Seok; Lim, Jong-Tae

    In this letter, we present the throughput analysis of the wireless ad hoc networks based on the IEEE 802.11 MAC (Medium Access Control). Especially, our analysis includes the case with the hidden node problem so that it can be applied to the multi-hop networks. In addition, we suggest a new channel access control algorithm to maximize the network throughput and show the usefulness of the proposed algorithm through simulations.

  2. A Framework for Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2016-01-01

    Speech enhancement is vital for improved listening practices. Ad hoc microphone arrays are promising assets for this purpose. Most well-established enhancement techniques with conventional arrays can be adapted into ad hoc scenarios. Despite recent efforts to introduce various ad hoc speech...... enhancement apparatus, a common framework for integration of conventional methods into this new scheme is still missing. This paper establishes such an abstraction based on inter and intra sub-array speech coherencies. Along with measures for signal quality at the input of sub-arrays, a measure of coherency...... is proposed both for sub-array selection in local enhancement approaches, and also for selecting a proper global reference when more than one sub-array are used. Proposed methods within this framework are evaluated with regard to quantitative and qualitative measures, including array gains, the speech...

  3. Sistem Verifikasi Tanda Tangan Off-Line Berdasar Ciri Histogram Of Oriented Gradient (HOG Dan Histogram Of Curvature (HoC

    Directory of Open Access Journals (Sweden)

    Agus Wahyu Widodo

    2015-08-01

    Full Text Available Abstrak Tanda tangan dengan sifat uniknya merupakan salah satu dari sekian banyak atribut personal yang diterima secara luas untuk verifikasi indentitas seseorang, alat pembuktian kepemilikan berbagai transaksi atau dokumen di dalam masyarakat. Keberhasilan penggunaan ciri gradien dan curvature dalam bidang-bidang penelitian pengenalan pola dan bahwa tanda tangan dapat dikatakan merupakan hasil tulisan tangan yang tersusun atas beragam garis dan lengkungan (curve yang memiliki arah atau orientasi merupakan alasan bahwa kedua ciri tersebut digunakan sebagai metoda verifikasi tanda tangan offline di penelitian ini. Berbagai implementasi dari pre-processing, ekstraksi dan representasi ciri, dan pembelajaran SVM serta usaha perbaikan yang telah dilakukan dalam penelitian ini menunjukkan hasil bahwa ciri HOG dan HoC mampu dimanfaatkan dalam proses verifikasi tanda tangan secara offline.  Pada basis data GPDS960Signature, HOG dan HoC yang dihitung pada ukuran sel 30 x 30 piksel memberikan dengan nilai %FRR terbaik 26,90 dan %FAR 37,56.  Sedangkan pada basis data FUM-PHSDB, HOG dn HoC yang dihitung pada ukuran 60 x 60 piksel memberikan nilai %FRR terbaik 4 dan %FAR 57. Kata kunci: verifikasi tanda tangan, curvature, orientation, gradient, histogram of curvature (HoC, histogram of oriented gradient (HOG Abstract Signature with unique properties is one of the many personal attributes that are widely accepted to verify a person's identity, proof of ownership transactions instrument or document in the community. The successful use of gradient and curvature feature in the research fields of pattern recognition is the reason that both of these features are used as an offline signature verification method in this study. Various implementations of preprocessing, feature extraction and representation, and SVM learning has been done in the study showed results that HOG and HoC feature can be utilized in the process of offline signature verification.  HOG and

  4. Handbook on theoretical and algorithmic aspects of sensor, ad hoc wireless, and peer-to-peer networks

    CERN Document Server

    Wu, Jie

    2005-01-01

    PrefaceAD HOC WIRELESS NETWORKSA Modular Cross Layer Architecture for Ad Hoc Networks, M. Conti, J. Crowcroft, G. Maselli, and G. TuriRouting Scalability in MANETs, J. Eriksson, S. Krishnamurthy and M. FaloutsosUniformly Distributed Algorithm for Virtual Backbone Routing in Ad Hoc Wireless Networks, D.S. KimMaximum Necessary Hop Count for Packet Routing in MANET, X. Chen and J. ShenEfficient Strategyproof Multicast in Selfish Wireless Networks, X.-Yang LiGeocasting in Ad Hoc and Sensor Networks, I. StojmenovicTopology Control for Ad hoc Networks: Present Solutions and Open Issues, C.-C. Shen a

  5. Fault Tolerant Mechanism for Multimedia Flows in Wireless Ad Hoc Networks Based on Fast Switching Paths

    Directory of Open Access Journals (Sweden)

    Juan R. Diaz

    2014-01-01

    Full Text Available Multimedia traffic can be forwarded through a wireless ad hoc network using the available resources of the nodes. Several models and protocols have been designed in order to organize and arrange the nodes to improve transmissions along the network. We use a cluster-based framework, called MWAHCA architecture, which optimizes multimedia transmissions over a wireless ad hoc network. It was proposed by us in a previous research work. This architecture is focused on decreasing quality of service (QoS parameters like latency, jitter, and packet loss, but other network features were not developed, like load balance or fault tolerance. In this paper, we propose a new fault tolerance mechanism, using as a base the MWAHCA architecture, in order to recover any multimedia flow crossing the wireless ad hoc network when there is a node failure. The algorithm can run independently for each multimedia flow. The main objective is to keep the QoS parameters as low as possible. To achieve this goal, the convergence time must be controlled and reduced. This paper provides the designed protocol, the analytical model of the algorithm, and a software application developed to test its performance in a real laboratory.

  6. Migraine patients consistently show abnormal vestibular bedside tests.

    Science.gov (United States)

    Maranhão, Eliana Teixeira; Maranhão-Filho, Péricles; Luiz, Ronir Raggio; Vincent, Maurice Borges

    2016-01-01

    Migraine and vertigo are common disorders, with lifetime prevalences of 16% and 7% respectively, and co-morbidity around 3.2%. Vestibular syndromes and dizziness occur more frequently in migraine patients. We investigated bedside clinical signs indicative of vestibular dysfunction in migraineurs. To test the hypothesis that vestibulo-ocular reflex, vestibulo-spinal reflex and fall risk (FR) responses as measured by 14 bedside tests are abnormal in migraineurs without vertigo, as compared with controls. Cross-sectional study including sixty individuals - thirty migraineurs, 25 women, 19-60 y-o; and 30 gender/age healthy paired controls. Migraineurs showed a tendency to perform worse in almost all tests, albeit only the Romberg tandem test was statistically different from controls. A combination of four abnormal tests better discriminated the two groups (93.3% specificity). Migraine patients consistently showed abnormal vestibular bedside tests when compared with controls.

  7. Security Testing in Agile Web Application Development - A Case Study Using the EAST Methodology

    CERN Document Server

    Erdogan, Gencer

    2010-01-01

    There is a need for improved security testing methodologies specialized for Web applications and their agile development environment. The number of web application vulnerabilities is drastically increasing, while security testing tends to be given a low priority. In this paper, we analyze and compare Agile Security Testing with two other common methodologies for Web application security testing, and then present an extension of this methodology. We present a case study showing how our Extended Agile Security Testing (EAST) performs compared to a more ad hoc approach used within an organization. Our working hypothesis is that the detection of vulnerabilities in Web applications will be significantly more efficient when using a structured security testing methodology specialized for Web applications, compared to existing ad hoc ways of performing security tests. Our results show a clear indication that our hypothesis is on the right track.

  8. Spontaneous ad hoc mobile cloud computing network.

    Science.gov (United States)

    Lacuesta, Raquel; Lloret, Jaime; Sendra, Sandra; Peñalver, Lourdes

    2014-01-01

    Cloud computing helps users and companies to share computing resources instead of having local servers or personal devices to handle the applications. Smart devices are becoming one of the main information processing devices. Their computing features are reaching levels that let them create a mobile cloud computing network. But sometimes they are not able to create it and collaborate actively in the cloud because it is difficult for them to build easily a spontaneous network and configure its parameters. For this reason, in this paper, we are going to present the design and deployment of a spontaneous ad hoc mobile cloud computing network. In order to perform it, we have developed a trusted algorithm that is able to manage the activity of the nodes when they join and leave the network. The paper shows the network procedures and classes that have been designed. Our simulation results using Castalia show that our proposal presents a good efficiency and network performance even by using high number of nodes.

  9. INDEPENDENSI HAKIM AD-HOC PADA LINGKUNGAN PERADILAN HUBUNGAN INDUSTRIAL / THE JUDICIAL INDEPENDENCE OF AD-HOC JUDGES IN INDUSTRIAL RELATION COURT

    Directory of Open Access Journals (Sweden)

    Muhammad Ishar Helmi

    2017-08-01

    Full Text Available Undang-Undang PPHI mengatur asas penyelesaian perselisihan hubungan industrial dilakukan secara musyawarah mufakat, dengan berprinsip jika terjadi perselisihan antara pekerja/buruh dan pengusaha maka tahap pertama penyelesaian perselisihan tersebut diserahkan pada pihak yang berselisih (bipartit. Ketentuan Pasal 63 ayat (2 dan Pasal 67 ayat (1 huruf f Undang-Undang tersebut mengakibatkan hakim ad-hoc Pengadilan Hubungan Industrial, dalam menjalankan tugas dan tanggung jawabnya memeriksa dan memutus suatu perkara harus mandiri dan lepas dari segala bentuk intervensi lembaga/instansi manapun menjadi terbatasi dan tidak optimal. Hakim ad-hoc Peradilan Hubungan Industrial merupakan hakim yang diusulkan oleh serikat pekerja/serikat buruh, organisasi pengusaha, juga diberhentikan secara hormat oleh serikat pekerja/serikat buruh, organisasi pengusaha tersebut. Hal ini tentunya akan menciderai sistem peradilan yang bebas, tidak memihak dan bersih yang diimpikan karena para hakim akan dikuasai oleh para pihak yang berperkara, karena keberadaan hakim diangkat dan diberhentikan oleh pihak yang akan disidangkan di peradilan hubungan industrial tersebut. PPHI (Industrial Relations Disputes Settlement Act regulates the principle of settlement of industrial relations disputes by consensus, if there is a dispute between employee/workers and employers, the first stage of dispute settlement shall be submitted to disputing party (bipartite settlement. The provisions of Article 63 paragraph (2 and Article 67 paragraph (1 sub-paragraph f of the Act shall result in the ad-hoc judges of the Industrial Relations Court, in carrying out their duties and responsibilities to examine and decide a case shall be independent and kept away from any intervention of any institution. The ad-hoc judges of the Industrial Relations Court is a judge proposed by a trade union, employers organization, also dismissed respectfully by the trade union and the employers organization. This

  10. Evolutionary algorithms for mobile ad hoc networks

    CERN Document Server

    Dorronsoro, Bernabé; Danoy, Grégoire; Pigné, Yoann; Bouvry, Pascal

    2014-01-01

    Describes how evolutionary algorithms (EAs) can be used to identify, model, and minimize day-to-day problems that arise for researchers in optimization and mobile networking. Mobile ad hoc networks (MANETs), vehicular networks (VANETs), sensor networks (SNs), and hybrid networks—each of these require a designer’s keen sense and knowledge of evolutionary algorithms in order to help with the common issues that plague professionals involved in optimization and mobile networking. This book introduces readers to both mobile ad hoc networks and evolutionary algorithms, presenting basic concepts as well as detailed descriptions of each. It demonstrates how metaheuristics and evolutionary algorithms (EAs) can be used to help provide low-cost operations in the optimization process—allowing designers to put some “intelligence” or sophistication into the design. It also offers efficient and accurate information on dissemination algorithms topology management, and mobility models to address challenges in the ...

  11. Throughput Capacity of Ad Hoc Networks with Route Discovery

    Directory of Open Access Journals (Sweden)

    Blum Rick S

    2007-01-01

    Full Text Available Throughput capacity of large ad hoc networks has been shown to scale adversely with the size of network . However the need for the nodes to find or repair routes has not been analyzed in this context. In this paper, we explicitly take route discovery into account and obtain the scaling law for the throughput capacity under general assumptions on the network environment, node behavior, and the quality of route discovery algorithms. We also discuss a number of possible scenarios and show that the need for route discovery may change the scaling for the throughput capacity.

  12. Topology for efficient information dissemination in ad-hoc networking

    Science.gov (United States)

    Jennings, E.; Okino, C. M.

    2002-01-01

    In this paper, we explore the information dissemination problem in ad-hoc wirless networks. First, we analyze the probability of successful broadcast, assuming: the nodes are uniformly distributed, the available area has a lower bould relative to the total number of nodes, and there is zero knowledge of the overall topology of the network. By showing that the probability of such events is small, we are motivated to extract good graph topologies to minimize the overall transmissions. Three algorithms are used to generate topologies of the network with guaranteed connectivity. These are the minimum radius graph, the relative neighborhood graph and the minimum spanning tree. Our simulation shows that the relative neighborhood graph has certain good graph properties, which makes it suitable for efficient information dissemination.

  13. Migraine patients consistently show abnormal vestibular bedside tests

    Directory of Open Access Journals (Sweden)

    Eliana Teixeira Maranhão

    2015-01-01

    Full Text Available Migraine and vertigo are common disorders, with lifetime prevalences of 16% and 7% respectively, and co-morbidity around 3.2%. Vestibular syndromes and dizziness occur more frequently in migraine patients. We investigated bedside clinical signs indicative of vestibular dysfunction in migraineurs.Objective To test the hypothesis that vestibulo-ocular reflex, vestibulo-spinal reflex and fall risk (FR responses as measured by 14 bedside tests are abnormal in migraineurs without vertigo, as compared with controls.Method Cross-sectional study including sixty individuals – thirty migraineurs, 25 women, 19-60 y-o; and 30 gender/age healthy paired controls.Results Migraineurs showed a tendency to perform worse in almost all tests, albeit only the Romberg tandem test was statistically different from controls. A combination of four abnormal tests better discriminated the two groups (93.3% specificity.Conclusion Migraine patients consistently showed abnormal vestibular bedside tests when compared with controls.

  14. Ad hoc public disclosure obligations of public companies on the capital market

    Directory of Open Access Journals (Sweden)

    Marjanski Vladimir

    2012-01-01

    Full Text Available The author gives a comprehensive analysis of the obligations of public companies regarding the provision of periodical (ad hoc information to the public on the capital market. Ad hoc disclosure is to achieve a number of aims. It is one of the devices to secure the market's functional abilities. By means of regularly fulfilling this obligation, the market is provided with all the relevant information necessary to form adequate prices of market materials - i.e. securities and other financial instruments (the function of market protection. Investors are thus being able to aptly respond to modified circumstances and deliver investment decisions whether to buy or sell market materials the price of which are being changed (the function of investor protection. Due to the fact that the duty of ad hoc disclosure encompasses the obligation to reveal insider information directly affecting the emitter, ad hoc disclosure serves as a preventive measure, i.e. as a protection against illicit trade with insider information (the function of prevention against the abuse of insider information.

  15. Selective epidemic broadcast algorithm to suppress broadcast storm in vehicular ad hoc networks

    Directory of Open Access Journals (Sweden)

    M. Chitra

    2018-03-01

    Full Text Available Broadcasting in Vehicular Ad Hoc Networks is the best way to spread emergency messages all over the network. With the dynamic nature of vehicular ad hoc networks, simple broadcast or flooding faces the problem called as Broadcast Storm Problem (BSP. The issue of the BSP will degrade the performance of a message broadcasting process like increased overhead, collision and dissemination delay. The paper is motivated to solve the problems in the existing Broadcast Strom Suppression Algorithms (BSSAs like p-Persistence, TLO, VSPB, G-SAB and SIR. This paper proposes to suppress the Broadcast Storm Problem and to improve the Emergency Safety message dissemination rate through a new BSSA based on Selective Epidemic Broadcast Algorithm (SEB. The simulation results clearly show that the SEB outperforms the existing algorithms in terms of ESM Delivery Ratio, Message Overhead, Collision Ratio, Broadcast Storm Ratio and Redundant Rebroadcast Ratio with decreased Dissemination Delay.

  16. Traffic Agents for Improving QoS in Mixed Infrastructure and Ad Hoc Modes Wireless LAN

    Directory of Open Access Journals (Sweden)

    Yuan Hai-Feng

    2006-01-01

    Full Text Available As an important complement to infrastructured wireless networks, mobile ad hoc networks (MANET are more flexible in providing wireless access services, but more difficult in meeting different quality of service (QoS requirements for mobile customers. Both infrastructure and ad hoc network structures are supported in wireless local area networks (WLAN, which can offer high data-rate wireless multimedia services to the mobile stations (MSs in a limited geographical area. For those out-of-coverage MSs, how to effectively connect them to the access point (AP and provide QoS support is a challenging issue. By mixing the infrastructure and the ad hoc modes in WLAN, we propose in this paper a new coverage improvement scheme that can identify suitable idle MSs in good service zones as traffic agents (TAs to relay traffic from those out-of-coverage MSs to the AP. The service coverage area of WLAN is then expanded. The QoS requirements (e.g., bandwidth of those MSs are considered in the selection process of corresponding TAs. Mathematical analysis, verified by computer simulations, shows that the proposed TA scheme can effectively reduce blocking probability when traffic load is light.

  17. Level of literacy and dementia: A secondary post-hoc analysis from North-West India

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Raina

    2014-01-01

    Full Text Available Introduction: A relation between literacy and dementia has been studied in past and an association has been documented. This is in spite of some studies pointing to the contrary. The current study was aimed at investigating the influence of level of literacy on dementia in a sample stratified by geography (Migrant, Urban, Rural and Tribal areas of sub-Himalayan state of Himachal Pradesh, India. Materials and Methods: The study was based on post-hoc analysis of data obtained from a study conducted on elderly population (60 years and above from selected geographical areas (Migrant, Urban, Rural and Tribal of Himachal Pradesh state in North-west India. Results: Analysis of variance revealed an effect of education on cognitive scores [F = 2.823, P =0.01], however, post-hoc Tukey′s HSD test did not reveal any significant pairwise comparisons. Discussion: The possibility that education effects dementia needs further evaluation, more so in Indian context.

  18. Node counting in wireless ad-hoc networks

    NARCIS (Netherlands)

    Evers, J.H.M.; Kiss, D.; Kowalczyk, W.; Navilarekallu, T.; Renger, D.R.M.; Sella, L.; Timperio, V.; Viorel, A.; Wijk, van A.C.C.; Yzelman, A.J.; Planqué, B.; Bhulai, S.; Hulshof, J.; Kager, W.; Rot, T.

    2012-01-01

    We study wireless ad-hoc networks consisting of small microprocessors with limited memory, where the wireless communication between the processors can be highly unreliable. For this setting, we propose a number of algorithms to estimate the number of nodes in the network, and the number of direct

  19. An implementation of traffic light system using multi-hop Ad hoc networks

    KAUST Repository

    Ansari, Imran Shafique

    2009-08-01

    In ad hoc networks nodes cooperate with each other to form a temporary network without the aid of any centralized administration. No wired base station or infrastructure is supported, and each host communicates via radio packets. Each host must act as a router, since routes are mostly multi-hop, due to the limited power transmission set by government agencies, (e.g. the Federal Communication Commission (FCC), which is 1 Watt in Industrial Scientific and Medical (ISM) band. The natures of wireless mobile ad hoc networks depend on batteries or other fatiguing means for their energy. A limited energy capacity may be the most significant performance constraint. Therefore, radio resource and power management is an important issue of any wireless network. In this paper, a design for traffic light system employing ad hoc networks is proposed. The traffic light system runs automatically based on signals sent through a multi-hop ad hoc network of \\'n\\' number of nodes utilizing the Token Ring protocol, which is efficient for this application from the energy prospective. The experiment consists of a graphical user interface that simulates the traffic lights and laptops (which have wireless network adapters) are used to run the graphical user interface and are responsible for setting up the ad hoc network between them. The traffic light system has been implemented utilizing A Mesh Driver (which allows for more than one wireless device to be connected simultaneously) and Java-based client-server programs. © 2009 IEEE.

  20. Ad Hoc on-Demand Distance Vector (AODV Routing Protocol Performance Evaluation on Hybrid Ad Hoc Network: Comparison of Result of Ns-2 Simulation and Implementation on Testbed using PDA

    Directory of Open Access Journals (Sweden)

    Riri Sari

    2010-10-01

    Full Text Available In Mobile Ad hoc NETwork (MANET, node supplemented with wireless equipment has the capacity to manage and organise autonomously, without the presence of network infrastructures. Hybrid ad hoc network, enable several nodes to move freely (mobile to create instant communication. Independent from infrastructure. They could access the Local Area Network (LAN or the Internet. Functionalities of ad hoc network very much dependent on the routing protocol that determines the routing around node. Ad hoc On-demand Distance Vector (AODV is one of routing protocols in ad hoc network which has a reactive characteristic. This protocol is the most common protocol being researched and used. In this Research, AODV protocol investigation was conducted by developing a testbed using Personal Computer, several Laptops (the Linux Red Hat operation system 9.0 and Fedora Core 2, and Personal Digital Assistant (PDA. This research also made a complete package by mean of cross compilation for PDA iPAQ. In general, results obtained from the simulation of AODV protocol using Network Simulator NS-2 are packet delivery ratio 99.89%, end-to-end delay of 0.14 seconds and routing overhead of 1,756.61 byte per second. Afterwards results from simulation were compared to results from testbed. Results obtained from testbed are as follows: the packet delivery ratio is 99.57%, the end-to-end delay is 1.004 seconds and the routing overhead is 1,360.36 byte per second.

  1. Adaptive Probabilistic Broadcasting over Dense Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Victor Gau

    2010-01-01

    Full Text Available We propose an idle probability-based broadcasting method, iPro, which employs an adaptive probabilistic mechanism to improve performance of data broadcasting over dense wireless ad hoc networks. In multisource one-hop broadcast scenarios, the modeling and simulation results of the proposed iPro are shown to significantly outperform the standard IEEE 802.11 under saturated condition. Moreover, the results also show that without estimating the number of competing nodes and changing the contention window size, the performance of the proposed iPro can still approach the theoretical bound. We further apply iPro to multihop broadcasting scenarios, and the experiment results show that within the same elapsed time after the broadcasting, the proposed iPro has significantly higher Packet-Delivery Ratios (PDR than traditional methods.

  2. Contribution to design a communication framework for vehicular ad hoc networks in urban scenarios

    OpenAIRE

    Tripp Barba, Carolina

    2013-01-01

    The constant mobility of people, the growing need to be always connected, the large number of vehicles that nowadays can be found in the roads and the advances in technology make Vehicular Ad hoc Networks (VANETs) be a major area of research. Vehicular Ad hoc Networks are a special type of wireless Mobile Ad hoc Networks (MANETs), which allow a group of mobile nodes configure a temporary network and maintain it without the need of a fixed infrastructure. A vehicular network presents some spec...

  3. Proposal of interference reduction routing for ad-hoc networks

    Directory of Open Access Journals (Sweden)

    Katsuhiro Naito

    2010-10-01

    Full Text Available In this paper, we propose an interference reduction routing protocol for ad-hoc networks. The interference is one of the degradation factors in wireless communications. In the ad-hoc network, some nodes communicate simultaneously. Therefore, these communications cause interference each other, and some packets are corrupted due to interference from another node. In the proposed protocol, each node estimates required transmission power according to hello messages. Therefore, the node can transmit a data packet with minimum required transmission power. Consequently, the interference against neighbor nodes can be reduced. From simulation results, we can find that the proposed protocol can reduce the number of control messages and can improve the throughput performance.

  4. Performance Analysis of Ad Hoc Dispersed Spectrum Cognitive Radio Networks over Fading Channels

    Directory of Open Access Journals (Sweden)

    Mohammad Muneer

    2011-01-01

    Full Text Available Cognitive radio systems can utilize dispersed spectrum, and thus such approach is known as dispersed spectrum cognitive radio systems. In this paper, we first provide the performance analysis of such systems over fading channels. We derive the average symbol error probability of dispersed spectrum cognitive radio systems for two cases, where the channel for each frequency diversity band experiences independent and dependent Nakagami- fading. In addition, the derivation is extended to include the effects of modulation type and order by considering M-ary phase-shift keying ( -PSK and M-ary quadrature amplitude modulation -QAM schemes. We then consider the deployment of such cognitive radio systems in an ad hoc fashion. We consider an ad hoc dispersed spectrum cognitive radio network, where the nodes are assumed to be distributed in three dimension (3D. We derive the effective transport capacity considering a cubic grid distribution. Numerical results are presented to verify the theoretical analysis and show the performance of such networks.

  5. An Agent-Based Approach To Nodes Misbehaviour Detection In Mobile Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    Otor Samera U.

    2017-02-01

    Full Text Available Existing Misbehaviour Detection Systems in Mobile Ad-hoc Networks MANETs are challenged with routing overhead and high latency resulting from complexity and failure to isolate and block misbehaving nodes for the reason that it is difficult to detect them as they participate fully in route finding. In this work a Mobile Agent-Based Acknowledgement scheme MAACK was formulated to address this problem using an object oriented algorithm deployed to report misbehaving nodes to the source and destination by registering the Internet Protocol IP address of misbehaving nodes in their header. The scheme was simulated using Network Simulator-3 NS-3 and results benchmarked with an existing scheme the Enhanced Adaptive Acknowledgment EAACK using packet delivery ratio routing overhead and latency as performance metrics in the two scenarios. The results showed that the MAACK paradigm guaranteed a higher packet delivery ratio lower latency and routing overhead than the EAACK scheme. The model can be adapted by Ad-Hoc network protocol developers.

  6. Worm epidemics in wireless ad hoc networks

    Energy Technology Data Exchange (ETDEWEB)

    Nekovee, Maziar [BT Research, Polaris 134, Adastral Park, Martlesham, Suffolk IP5 3RE (United Kingdom); Centre for Computational Science, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2007-06-15

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

  7. Worm epidemics in wireless ad hoc networks

    Science.gov (United States)

    Nekovee, Maziar

    2007-06-01

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

  8. Worm epidemics in wireless ad hoc networks

    International Nuclear Information System (INIS)

    Nekovee, Maziar

    2007-01-01

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet

  9. Voice Communications over 802.11 Ad Hoc Networks: Modeling, Optimization and Call Admission Control

    Science.gov (United States)

    Xu, Changchun; Xu, Yanyi; Liu, Gan; Liu, Kezhong

    Supporting quality-of-service (QoS) of multimedia communications over IEEE 802.11 based ad hoc networks is a challenging task. This paper develops a simple 3-D Markov chain model for queuing analysis of IEEE 802.11 MAC layer. The model is applied for performance analysis of voice communications over IEEE 802.11 single-hop ad hoc networks. By using the model, we finish the performance optimization of IEEE MAC layer and obtain the maximum number of voice calls in IEEE 802.11 ad hoc networks as well as the statistical performance bounds. Furthermore, we design a fully distributed call admission control (CAC) algorithm which can provide strict statistical QoS guarantee for voice communications over IEEE 802.11 ad hoc networks. Extensive simulations indicate the accuracy of the analytical model and the CAC scheme.

  10. Ad Hoc Wireless Networking and Shared Computation for Autonomous Multirobot Systems

    OpenAIRE

    Bevilacqua, Riccardo; Hall, Jason S.; Horning, James; Romano, Marcello

    2009-01-01

    The article of record as published may be located at http://dx.doi.org/10.2514/1.40734 A wireless ad hoc network is introduced that enables inter-robot communication and shared computation among multiple robots with PC/104-based single board computers running the real-time application interface patched Linux operating system. Through the use of IEEE 802.11 ad hoc technology and User Datagram Protocol, each robot is able to exchange data without the need of a centralized router ...

  11. The Ex Hoc Infrastructure - Enhancing Traffic Safety through LIfe WArning Systems

    DEFF Research Database (Denmark)

    Hansen, Klaus Marius; Kristensen, Lars Michael; Eskildsen, Toke

    2004-01-01

    New pervasive computing technologies for sensing and communication open up novel possibilities for enhancing traffic safety. We are currently designing and implementing the Ex Hoc infrastructure framework for communication among mobile and stationary units including vehicles. The infrastructure...... will connect sensing devices on vehicles with sensing devices on other vehicles and with stationary communication units placed alongside roads. The current application of Ex Hoc is to enable the collection and dissemination of information on road condition through LIfe Warning Systems (LIWAS) units....

  12. Analysis of DDoS Attack Effect and Protection Scheme in Wireless Mobile Ad-hoc Network

    OpenAIRE

    Ramratan Ahirwal; Leeladhar Mahour

    2012-01-01

    In Wireless mobile Ad Hoc Networks (MANET) every node functions as transmitter, router and data sink is network without infrastructure. Detecting malicious nodes in an open ad-hoc network in whichparticipating nodes have no previous security associations presents a number of challenges not faced by traditional wired networks. Traffic monitoring in wired networks is usually performed at switches,routers and gateways, but an ad-hoc network does not have these types of network elements where the...

  13. Performance Analysis of Mobile Ad Hoc Unmanned Aerial Vehicle Communication Networks with Directional Antennas

    Directory of Open Access Journals (Sweden)

    Abdel Ilah Alshbatat

    2010-01-01

    Full Text Available Unmanned aerial vehicles (UAVs have the potential of creating an ad hoc communication network in the air. Most UAVs used in communication networks are equipped with wireless transceivers using omnidirectional antennas. In this paper, we consider a collection of UAVs that communicate through wireless links as a mobile ad-hoc network using directional antennas. The network design goal is to maximize the throughput and minimize the end-to-end delay. In this respect, we propose a new medium access control protocol for a network of UAVs with directional antennas. We analyze the communication channel between the UAVs and the effect of aircraft attitude on the network performance. Using the optimized network engineering tool (OPNET, we compare our protocol with the IEEE 802.11 protocol for omnidirectional antennas. The simulation results show performance improvement in end-to-end delay as well as throughput.

  14. Cognitive radio application for vehicular ad hoc networks (VANETS

    Directory of Open Access Journals (Sweden)

    Miladić Suzana D.

    2016-01-01

    Full Text Available This paper presents the application of cognitive radio technology in vehicular ad-hoc networks aimed to improve the communications between vehicles themselves as well as between vehicles and roadside infrastructure. Due to dynamic approach of spectrum access, cognitive radio is a technology that enables more efficient usage of radio-frequency spectrum. We review actual approaches and discuss research challenges related to the use of cognitive radio technology in vehicular ad hoc networks with emphasis on architecture, spectrum management as well as QoS optimization. The researching on cognitive radio application in vehicular networks is still developing and there are not many experimental platforms due to their complex setups. Some related research projects and cognitive radio realizations are provided in this paper.

  15. Ad Hoc Physical Hilbert Spaces in Quantum Mechanics

    Czech Academy of Sciences Publication Activity Database

    Fernandez, F. M.; Garcia, J.; Semorádová, Iveta; Znojil, Miloslav

    2015-01-01

    Roč. 54, č. 12 (2015), s. 4187-4203 ISSN 0020-7748 Institutional support: RVO:61389005 Keywords : quantum mechanics * physical Hilbert spaces * ad hoc inner product * singular potentials regularized * low lying energies Subject RIV: BE - Theoretical Physics Impact factor: 1.041, year: 2015

  16. Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Hong-Chuan Yang

    2007-01-01

    Full Text Available We study the energy-efficient configuration of multihop paths with automatic repeat request (ARQ mechanism in wireless ad hoc networks. We adopt a cross-layer design approach and take both the quality of each radio hop and the battery capacity of each transmitting node into consideration. Under certain constraints on the maximum tolerable transmission delay and the required packet delivery ratio, we solve optimization problems to jointly schedule the transmitting power of each transmitting node and the retransmission limit over each hop. Numerical results demonstrate that the path configuration methods can either significantly reduce the average energy consumption per packet delivery or considerably extend the average lifetime of the multihop route.

  17. Contribution to design a communication framework for vehicular ad hoc networks in urban scenarios

    OpenAIRE

    Tripp Barba, Carolina

    2013-01-01

    La movilidad constante de las personas y la creciente necesidad de estar conectados en todo momento ha hecho de las redes vehiculares un área cuyo interés ha ido en aumento. La gran cantidad de vehículos que hay en la actualidad, y los avances tecnológicos han hecho de las redes vehiculares (VANETS, Vehicular Ad hoc Networks) un gran campo de investigación. Las redes vehiculares son un tipo especial de redes móviles ad hoc inalámbricas, las cuales, al igual que las redes MANET (Mobile Ad hoc ...

  18. Source Authentication for Multicast in Mobile Ad Hoc Networks

    National Research Council Canada - National Science Library

    Ramachandran, Prabha

    2003-01-01

    Recent emergence and popularity of mobile ad hoc networks in a host of current-day applications has instigated a suite of research challenges, primarily in routing and security issues for such networks...

  19. A peer-to-peer file search and download protocol for wireless ad-hoc networks

    NARCIS (Netherlands)

    Sözer, Hasan; Tekkalmaz, M.; Korpeoglu, I.

    Deployment of traditional peer-to-peer file sharing systems on a wireless ad-hoc network introduces several challenges. Information and workload distribution as well as routing are major problems for members of a wireless ad-hoc network, which are only aware of their immediate neighborhood. In this

  20. Analysis and Enhancements of Leader Elections algorithms in Mobile Ad Hoc Networks

    OpenAIRE

    Shayeji, Mohammad H. Al; Al-Azmi, AbdulRahman R.; Al-Azmi, AbdulAziz R.; Samrajesh, M. D.

    2012-01-01

    Mobile Ad Hoc networks (MANET), distinct from traditional distributed systems, are dynamic and self-organizing networks. MANET requires a leader to coordinate and organize tasks. The challenge is to have the right election algorithm that chooses the right leader based on various factors in MANET. In this paper, we analyze four leader election algorithms used in mobile Ad Hoc Networks. Factors considered in our analysis are time complexity, message complexity, assumptions considered, fault tol...

  1. User-centred and context-aware identity management in mobile ad-hoc networks

    CERN Document Server

    Arabo, Abdullahi

    2013-01-01

    The emergent notion of ubiquitous computing makes it possible for mobile devices to communicate and provide services via networks connected in an ad-hoc manner. These have resulted in the proliferation of wireless technologies such as Mobile Ad-hoc Networks (MANets), which offer attractive solutions for services that need flexible setup as well as dynamic and low cost wireless connectivity. However, the growing trend outlined above also raises serious concerns over Identity Management (IM) du...

  2. Centralized cooperative spectrum sensing for ad-hoc disaster relief network clusters

    DEFF Research Database (Denmark)

    Pratas, Nuno; Marchetti, Nicola; Prasad, Neeli R.

    2010-01-01

    Disaster relief networks have to be highly adaptable and resilient. Cognitive radio enhanced ad-hoc architecture have been put forward as a candidate to enable such networks. Spectrum sensing is the cornerstone of the cognitive radio paradigm, and it has been the target of intensive research....... The main common conclusion was that the achievable spectrum sensing accuracy can be greatly enhanced through the use of cooperative sensing schemes. When considering applying Cognitive Radio to ad-hoc disaster relief networks, spectrum sensing cooperative schemes are paramount. A centralized cluster...

  3. LAMAN: Load Adaptable MAC for Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Realp Marc

    2005-01-01

    Full Text Available In mobile ad hoc radio networks, mechanisms on how to access the radio channel are extremely important in order to improve network efficiency. In this paper, the load adaptable medium access control for ad hoc networks (LAMAN protocol is described. LAMAN is a novel decentralized multipacket MAC protocol designed following a cross-layer approach. Basically, this protocol is a hybrid CDMA-TDMA-based protocol that aims at throughput maximization in multipacket communication environments by efficiently combining contention and conflict-free protocol components. Such combination of components is used to adapt the nodes' access priority to changes on the traffic load while, at the same time, accounting for the multipacket reception (MPR capability of the receivers. A theoretical analysis of the system is developed presenting closed expressions of network throughput and packet delay. By simulations the validity of our analysis is shown and the performances of a LAMAN-based system and an Aloha-CDMA-based one are compared.

  4. A multihop key agreement scheme for wireless ad hoc networks based on channel characteristics.

    Science.gov (United States)

    Hao, Zhuo; Zhong, Sheng; Yu, Nenghai

    2013-01-01

    A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM) adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks.

  5. Typicality Mediates Performance during Category Verification in Both Ad-Hoc and Well-Defined Categories

    Science.gov (United States)

    Sandberg, Chaleece; Sebastian, Rajani; Kiran, Swathi

    2012-01-01

    Background: The typicality effect is present in neurologically intact populations for natural, ad-hoc, and well-defined categories. Although sparse, there is evidence of typicality effects in persons with chronic stroke aphasia for natural and ad-hoc categories. However, it is unknown exactly what influences the typicality effect in this…

  6. On the impact of network dynamics on a discovery protocol for ad-hoc networks

    NARCIS (Netherlands)

    Liu, F.; Heijenk, Geert

    A very promising approach to discovering services and context information in ad-hoc networks is based on the use of Attenuated Bloom filters. In this paper we analyze the impact of changes in the connectivity of an ad-hoc network on this approach. We evaluate the performance of the discovery

  7. What Is the Problem of Ad Hoc Hypotheses?

    Science.gov (United States)

    Bamford, Greg

    1999-01-01

    Philosophers' attempts to convincingly explicate the received view of an ad hoc hypothesis--that it accounts for only the observations it was designed to account for--have been unsuccessful. Familiar and firmer criteria for evaluating the hypotheses or modified theories so classified are characteristically available. Contains 41 references.…

  8. FRCA: A Fuzzy Relevance-Based Cluster Head Selection Algorithm for Wireless Mobile Ad-Hoc Sensor Networks

    Directory of Open Access Journals (Sweden)

    Taegwon Jeong

    2011-05-01

    Full Text Available Clustering is an important mechanism that efficiently provides information for mobile nodes and improves the processing capacity of routing, bandwidth allocation, and resource management and sharing. Clustering algorithms can be based on such criteria as the battery power of nodes, mobility, network size, distance, speed and direction. Above all, in order to achieve good clustering performance, overhead should be minimized, allowing mobile nodes to join and leave without perturbing the membership of the cluster while preserving current cluster structure as much as possible. This paper proposes a Fuzzy Relevance-based Cluster head selection Algorithm (FRCA to solve problems found in existing wireless mobile ad hoc sensor networks, such as the node distribution found in dynamic properties due to mobility and flat structures and disturbance of the cluster formation. The proposed mechanism uses fuzzy relevance to select the cluster head for clustering in wireless mobile ad hoc sensor networks. In the simulation implemented on the NS-2 simulator, the proposed FRCA is compared with algorithms such as the Cluster-based Routing Protocol (CBRP, the Weighted-based Adaptive Clustering Algorithm (WACA, and the Scenario-based Clustering Algorithm for Mobile ad hoc networks (SCAM. The simulation results showed that the proposed FRCA achieves better performance than that of the other existing mechanisms.

  9. FRCA: a fuzzy relevance-based cluster head selection algorithm for wireless mobile ad-hoc sensor networks.

    Science.gov (United States)

    Lee, Chongdeuk; Jeong, Taegwon

    2011-01-01

    Clustering is an important mechanism that efficiently provides information for mobile nodes and improves the processing capacity of routing, bandwidth allocation, and resource management and sharing. Clustering algorithms can be based on such criteria as the battery power of nodes, mobility, network size, distance, speed and direction. Above all, in order to achieve good clustering performance, overhead should be minimized, allowing mobile nodes to join and leave without perturbing the membership of the cluster while preserving current cluster structure as much as possible. This paper proposes a Fuzzy Relevance-based Cluster head selection Algorithm (FRCA) to solve problems found in existing wireless mobile ad hoc sensor networks, such as the node distribution found in dynamic properties due to mobility and flat structures and disturbance of the cluster formation. The proposed mechanism uses fuzzy relevance to select the cluster head for clustering in wireless mobile ad hoc sensor networks. In the simulation implemented on the NS-2 simulator, the proposed FRCA is compared with algorithms such as the Cluster-based Routing Protocol (CBRP), the Weighted-based Adaptive Clustering Algorithm (WACA), and the Scenario-based Clustering Algorithm for Mobile ad hoc networks (SCAM). The simulation results showed that the proposed FRCA achieves better performance than that of the other existing mechanisms.

  10. Deny-by-Default Distributed Security Policy Enforcement in Mobile Ad Hoc Networks

    Science.gov (United States)

    Alicherry, Mansoor; Keromytis, Angelos D.; Stavrou, Angelos

    Mobile Ad-hoc Networks (MANETs) are increasingly employed in tactical military and civil rapid-deployment networks, including emergency rescue operations and ad hoc disaster-relief networks. However, this flexibility of MANETs comes at a price, when compared to wired and base station-based wireless networks: MANETs are susceptible to both insider and outsider attacks. This is mainly because of the lack of a well-defined defense perimeter preventing the effective use of wired defenses including firewalls and intrusion detection systems.

  11. Multiplayer Game for DDoS Attacks Resilience in Ad Hoc Networks

    DEFF Research Database (Denmark)

    Mikalas, Antonis; Komninos, Nikos; Prasad, Neeli R.

    2011-01-01

    This paper proposes a multiplayer game to prevent Distributed Denial of Service attack (DDoS) in ad hoc networks. The multiplayer game is based on game theory and cryptographic puzzles. We divide requests from nodes into separate groups which decreases the ability of malicious nodes to cooperate...... with one another in order to effectively make a DDoS attack. Finally, through our experiments we have shown that the total overhead of the multiplayer game as well as the the total time that each node needs to be served is affordable for devices that have limited resources and for environments like ad hoc...

  12. Ad Hoc Human Information Nets for Asymmetric Threat Surveillance

    National Research Council Canada - National Science Library

    Thiruvathukal, George

    2003-01-01

    ...: Hybrid-Hierarchical Micro-Databases, Query Optimization, and XML for Embedded Systems. After meeting with the program manager, Tom Armour, in Washington, DC, we were able to get a better perspective on the ad hoc nature of the solicitation...

  13. Modelling Mobility in Mobile AD-HOC Network Environments ...

    African Journals Online (AJOL)

    In the simulation of mobile ad-hoc networks (MANETs), the probability distribution governing the movement of nodes typically varies over time and converges to a steady state distribution, known as the stationary distribution. This paper presents and evaluates the stationary distribution for location, speed and pause time of a ...

  14. Dynamic Mobile IP routers in ad hoc networks

    NARCIS (Netherlands)

    Kock, B.A.; Schmidt, J.R.

    2005-01-01

    This paper describes a concept combining mobile IP and ad hoc routing to create a robust mobile network. In this network all nodes are mobile and globally and locally reachable under the same IP address. Essential for implementing this network are the dynamic mobile IP routers. They act as gateways

  15. Energy management in wireless cellular and ad-hoc networks

    CERN Document Server

    Imran, Muhammad; Qaraqe, Khalid; Alouini, Mohamed-Slim; Vasilakos, Athanasios

    2016-01-01

    This book investigates energy management approaches for energy efficient or energy-centric system design and architecture and presents end-to-end energy management in the recent heterogeneous-type wireless network medium. It also considers energy management in wireless sensor and mesh networks by exploiting energy efficient transmission techniques and protocols. and explores energy management in emerging applications, services and engineering to be facilitated with 5G networks such as WBANs, VANETS and Cognitive networks. A special focus of the book is on the examination of the energy management practices in emerging wireless cellular and ad hoc networks. Considering the broad scope of energy management in wireless cellular and ad hoc networks, this book is organized into six sections covering range of Energy efficient systems and architectures; Energy efficient transmission and techniques; Energy efficient applications and services. .

  16. Power-Controlled MAC Protocols with Dynamic Neighbor Prediction for Ad hoc Networks

    Institute of Scientific and Technical Information of China (English)

    LI Meng; ZHANG Lin; XIAO Yong-kang; SHAN Xiu-ming

    2004-01-01

    Energy and bandwidth are the scarce resources in ad hoc networks because most of the mobile nodes are battery-supplied and share the exclusive wireless medium. Integrating the power control into MAC protocol is a promising technique to fully exploit these precious resources of ad hoc wireless networks. In this paper, a new intelligent power-controlled Medium Access Control (MAC) (iMAC) protocol with dynamic neighbor prediction is proposed. Through the elaborate design of the distributed transmit-receive strategy of mobile nodes, iMAC greatly outperforms the prevailing IEEE 802.11 MAC protocols in not only energy conservation but also network throughput. Using the Dynamic Neighbor Prediction (DNP), iMAC performs well in mobile scenes. To the best of our knowledge, iMAC is the first protocol that considers the performance deterioration of power-controlled MAC protocols in mobile scenes and then proposes a solution. Simulation results indicate that DNP is important and necessary for power-controlled MAC protocols in mobile ad hoc networks.

  17. Undilatable Stent Neoatherosclerosis Treated with Ad Hoc Rotational Atherectomy

    Directory of Open Access Journals (Sweden)

    Michael Koutouzis

    2017-01-01

    Full Text Available A middle age woman with known ischemic heart disease and old stents in proximal left anterior descending coronary artery (LAD was admitted to Coronary Care Unit with acute coronary syndrome. The coronary angiography showed one vessel disease with significant restenosis within the previously implanted stents. The lesion was tough and remained undilatable despite high pressure balloon inflation. Eventually, the balloon ruptured creating a massive dissection of the LAD beginning immediately after the distal part of the undilatable lesion. We proceeded with a challenging ad hoc rotational atherectomy of the lesion and finally stenting of the lesion. In-stent restenosis many years after stent implantation is considered to be mainly due to neoatheromatosis compared to intimal hyperplasia, making lesion treatment more difficult and unpredictable.

  18. Preventive Ceftriaxone in Patients with Stroke Treated with Intravenous Thrombolysis: Post Hoc Analysis of the Preventive Antibiotics in Stroke Study

    NARCIS (Netherlands)

    Vermeij, Jan-Dirk; Westendorp, Willeke F.; Roos, Yvo B.; Brouwer, Matthijs C.; van de Beek, Diederik; Nederkoorn, Paul J.

    2016-01-01

    The Preventive Antibiotics in Stroke Study (PASS), a randomized open-label masked endpoint trial, showed that preventive ceftriaxone did not improve functional outcome at 3 months in patients with acute stroke (adjusted common OR 0.95; 95% CI 0.82-1.09). Post-hoc analyses showed that among patients

  19. Intelligent QoS routing algorithm based on improved AODV protocol for Ad Hoc networks

    Science.gov (United States)

    Huibin, Liu; Jun, Zhang

    2016-04-01

    Mobile Ad Hoc Networks were playing an increasingly important part in disaster reliefs, military battlefields and scientific explorations. However, networks routing difficulties are more and more outstanding due to inherent structures. This paper proposed an improved cuckoo searching-based Ad hoc On-Demand Distance Vector Routing protocol (CSAODV). It elaborately designs the calculation methods of optimal routing algorithm used by protocol and transmission mechanism of communication-package. In calculation of optimal routing algorithm by CS Algorithm, by increasing QoS constraint, the found optimal routing algorithm can conform to the requirements of specified bandwidth and time delay, and a certain balance can be obtained among computation spending, bandwidth and time delay. Take advantage of NS2 simulation software to take performance test on protocol in three circumstances and validate the feasibility and validity of CSAODV protocol. In results, CSAODV routing protocol is more adapt to the change of network topological structure than AODV protocol, which improves package delivery fraction of protocol effectively, reduce the transmission time delay of network, reduce the extra burden to network brought by controlling information, and improve the routing efficiency of network.

  20. Distributed generation of shared RSA keys in mobile ad hoc networks

    Science.gov (United States)

    Liu, Yi-Liang; Huang, Qin; Shen, Ying

    2005-12-01

    Mobile Ad Hoc Networks is a totally new concept in which mobile nodes are able to communicate together over wireless links in an independent manner, independent of fixed physical infrastructure and centralized administrative infrastructure. However, the nature of Ad Hoc Networks makes them very vulnerable to security threats. Generation and distribution of shared keys for CA (Certification Authority) is challenging for security solution based on distributed PKI(Public-Key Infrastructure)/CA. The solutions that have been proposed in the literature and some related issues are discussed in this paper. The solution of a distributed generation of shared threshold RSA keys for CA is proposed in the present paper. During the process of creating an RSA private key share, every CA node only has its own private security. Distributed arithmetic is used to create the CA's private share locally, and that the requirement of centralized management institution is eliminated. Based on fully considering the Mobile Ad Hoc network's characteristic of self-organization, it avoids the security hidden trouble that comes by holding an all private security share of CA, with which the security and robustness of system is enhanced.

  1. Verification of mobile ad hoc networks : an algebraic approach

    NARCIS (Netherlands)

    Ghassemi, F.; Fokkink, W.J.; Movaghar, A.

    2011-01-01

    We introduced Computed Network Process Theory to reason about protocols for mobile ad hoc networks (MANETs). Here we explore the applicability of our framework in two regards: model checking and equational reasoning. The operational semantics of our framework is based on constrained labeled

  2. Authentication and consensus overhead in vehicular ad hoc networks

    NARCIS (Netherlands)

    Petit, Jonathan; Mammeri, Zoubir

    Vehicular ad hoc networks aim at increasing passenger safety by exchanging warning messages between vehicles wirelessly. A main challenge is to resist to various malicious abuses and security attacks. However, any security mechanism comes with overhead. We analyze how the authentication algorithm

  3. Challenges of evidence acquisition in wireless ad-hoc networks

    CSIR Research Space (South Africa)

    Mutanga, MB

    2010-05-01

    Full Text Available a big challenge. Thus, the aim of this paper is to explore the challenges of acquiring live evidence in wireless ad-hoc networks. We also give some legal requirements of evidence admissibility as outlined in the Communications and Transactions Act...

  4. A New Hybrid Channel Access Scheme for Ad Hoc Networks

    National Research Council Canada - National Science Library

    Wang, Yu; Garcia-Luna-Aceves, J. J

    2002-01-01

    Many contention-based channel access schemes have been proposed for multi-hop ad hoc networks in the recent past, and they can be divided into two categories, sender-initiated and receiver-initiated...

  5. Enabling Real-Time Video Services over Ad-Hoc Networks Opens the Gates for E-learning in Areas Lacking Infrastructure

    Directory of Open Access Journals (Sweden)

    Johannes Karlsson

    2009-10-01

    Full Text Available In this paper we suggest a promising solution to come over the problems of delivering e-learning to areas with lack or deficiencies in infrastructure for Internet and mobile communication. We present a simple, reasonably priced and efficient communication platform for providing e-learning. This platform is based on wireless ad-hoc networks. We also present a preemptive routing protocol suitable for real-time video communication over wireless ad-hoc networks. Our results show that this routing protocol can significantly improve the quality of the received video. This makes our suggested system not only good to overcome the infrastructure barrier but even capable of delivering a high quality e-learning material.

  6. History of the research ad hoc committee on 'dissemination of information' and the special ad hoc committee on 'dissemination of information' of the Atomic Energy Society of Japan

    Energy Technology Data Exchange (ETDEWEB)

    Itabashi, Keizo [Japan Atomic Energy Agency, Intellectual Resources Department, Tokai, Ibaraki (Japan)

    2010-06-15

    The Research ad hoc committee on 'Dissemination of information' of the Atomic Energy Society of Japan was held 15 times from Oct. 1970 to Mar 1973. After that, The Special ad hoc committee on 'Dissemination of information' of the Atomic Energy Society of Japan was held 115 times from Apr. 1973 to Mar 2009. The history of these two committees is described. Activity report is arranged including the information on change of the member and topics of the meeting, and the minutes. Furthermore, the document list on International Nuclear Information System (INIS) from Japan is included. (author)

  7. History of the research ad hoc committee on 'dissemination of information' and the special ad hoc committee on 'dissemination of information' of the Atomic Energy Society of Japan

    International Nuclear Information System (INIS)

    Itabashi, Keizo

    2010-06-01

    The Research ad hoc committee on 'Dissemination of information' of the Atomic Energy Society of Japan was held 15 times from Oct. 1970 to Mar 1973. After that, The Special ad hoc committee on 'Dissemination of information' of the Atomic Energy Society of Japan was held 115 times from Apr. 1973 to Mar 2009. The history of these two committees is described. Activity report is arranged including the information on change of the member and topics of the meeting, and the minutes. Furthermore, the document list on International Nuclear Information System (INIS) from Japan is included. (author)

  8. On the Geometrical Characteristics of Three-Dimensional Wireless Ad Hoc Networks and Their Applications

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available In a wireless ad hoc network, messages are transmitted, received, and forwarded in a finite geometrical region and the transmission of messages is highly dependent on the locations of the nodes. Therefore the study of geometrical relationship between nodes in wireless ad hoc networks is of fundamental importance in the network architecture design and performance evaluation. However, most previous works concentrated on the networks deployed in the two-dimensional region or in the infinite three-dimensional space, while in many cases wireless ad hoc networks are deployed in the finite three-dimensional space. In this paper, we analyze the geometrical characteristics of the three-dimensional wireless ad hoc network in a finite space in the framework of random graph and deduce an expression to calculate the distance probability distribution between network nodes that are independently and uniformly distributed in a finite cuboid space. Based on the theoretical result, we present some meaningful results on the finite three-dimensional network performance, including the node degree and the max-flow capacity. Furthermore, we investigate some approximation properties of the distance probability distribution function derived in the paper.

  9. VMQL: A Visual Language for Ad-Hoc Model Querying

    DEFF Research Database (Denmark)

    Störrle, Harald

    2011-01-01

    In large scale model based development, analysis level models are more like knowledge bases than engineering artifacts. Their effectiveness depends, to a large degree, on the ability of domain experts to retrieve information from them ad hoc. For large scale models, however, existing query...

  10. Access Point Security Service for wireless ad-hoc communication

    NARCIS (Netherlands)

    Scholten, Johan; Nijdam, M.

    2006-01-01

    This paper describes the design and implementation of a security solution for ad-hoc peer-to-peer communication. The security solution is based on a scenario where two wireless devices require secure communication, but share no security relationship a priori. The necessary requirements for the

  11. A Novel Routing Algorithm for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Raúl Aquino Santos

    2008-01-01

    Full Text Available Este trabajo examina la importancia de las redes inalámbricas ad hoc y el algoritmo de enrutamiento con inundación basada en grupos (LORA-CBF para la comunicación inter-vehicular con la finalidad de optimizar el flujo de tráfico e incrementar la seguridad en las autopistas. Se discute el algoritmo de enrutamiento LORA-CBF y se presentan los resultados de simulaciones realizadas en OPNET de una autopista con alta movilidad vehicular. Primero, el modelo de simulación propuesto se valida a pequeña escala con resultados experimentales. Posteriormente, se emplean simulaciones de nuestro modelo comparándolos con Ad Hoc On-Demand Distance Vector (AODV y Dynamic Source Routing (DSR. Finalmente, se emplea un modelo de tráfico microscópico desarrollado en OPNET para simular la movilidad de 250 vehículos en una autopista y se aplica el algoritmo de enrutamiento LORA-CBF en un escenario vehicular.

  12. Post hoc support vector machine learning for impedimetric biosensors based on weak protein-ligand interactions.

    Science.gov (United States)

    Rong, Y; Padron, A V; Hagerty, K J; Nelson, N; Chi, S; Keyhani, N O; Katz, J; Datta, S P A; Gomes, C; McLamore, E S

    2018-04-30

    Impedimetric biosensors for measuring small molecules based on weak/transient interactions between bioreceptors and target analytes are a challenge for detection electronics, particularly in field studies or in the analysis of complex matrices. Protein-ligand binding sensors have enormous potential for biosensing, but achieving accuracy in complex solutions is a major challenge. There is a need for simple post hoc analytical tools that are not computationally expensive, yet provide near real time feedback on data derived from impedance spectra. Here, we show the use of a simple, open source support vector machine learning algorithm for analyzing impedimetric data in lieu of using equivalent circuit analysis. We demonstrate two different protein-based biosensors to show that the tool can be used for various applications. We conclude with a mobile phone-based demonstration focused on the measurement of acetone, an important biomarker related to the onset of diabetic ketoacidosis. In all conditions tested, the open source classifier was capable of performing as well as, or better, than the equivalent circuit analysis for characterizing weak/transient interactions between a model ligand (acetone) and a small chemosensory protein derived from the tsetse fly. In addition, the tool has a low computational requirement, facilitating use for mobile acquisition systems such as mobile phones. The protocol is deployed through Jupyter notebook (an open source computing environment available for mobile phone, tablet or computer use) and the code was written in Python. For each of the applications, we provide step-by-step instructions in English, Spanish, Mandarin and Portuguese to facilitate widespread use. All codes were based on scikit-learn, an open source software machine learning library in the Python language, and were processed in Jupyter notebook, an open-source web application for Python. The tool can easily be integrated with the mobile biosensor equipment for rapid

  13. Minimizing Broadcast Expenses in Clustered Ad-hoc Networks

    Directory of Open Access Journals (Sweden)

    S. Zeeshan Hussain

    2018-01-01

    Full Text Available One way to minimize the broadcast expenses of routing protocols is to cluster the network. In clustered ad-hoc networks, all resources can be managed easily by resolving scalability issues. However, blind query broadcast is a major issue that leads to the broadcast storm problem in clustered ad-hoc networks. This query broadcast is done to carry out the route-search task that leads to the unnecessary propagation of route-query even after route has been found. Hence, this query propagation poses the problem of congestion in the network. In particular this motivates us to propose a query-control technique in such networks which works based on broadcast repealing. A huge amount of work has been devoted to propose the query control broadcasting techniques. However, such techniques used in traditional broadcasting mechanisms need to be properly extended for use in the cluster based routing architecture. In this paper, query-control technique is proposed for cluster based routing technique to reduce the broadcast expenses. Finally, we report some experiments which compare the proposed technique to other commonly used techniques including standard one-class AODV that follows TTL-sequence based broadcasting technique.

  14. Service for fault tolerance in the Ad Hoc Networks based on Multi Agent Systems

    Directory of Open Access Journals (Sweden)

    Ghalem Belalem

    2011-02-01

    Full Text Available The Ad hoc networks are distributed networks, self-organized and does not require infrastructure. In such network, mobile infrastructures are subject of disconnections. This situation may concern a voluntary or involuntary disconnection of nodes caused by the high mobility in the Ad hoc network. In these problems we are trying through this work to contribute to solving these problems in order to ensure continuous service by proposing our service for faults tolerance based on Multi Agent Systems (MAS, which predict a problem and decision making in relation to critical nodes. Our work contributes to study the prediction of voluntary and involuntary disconnections in the Ad hoc network; therefore we propose our service for faults tolerance that allows for effective distribution of information in the Network by selecting some objects of the network to be duplicates of information.

  15. What We Know about Software Test Maturity and Test Process Improvement

    NARCIS (Netherlands)

    Garousi, Vahid; Felderer, Michael; Hacaloglu, Tuna

    2018-01-01

    In many companies, software testing practices and processes are far from mature and are usually conducted in an ad hoc fashion. Such immature practices lead to negative outcomes - for example, testing that doesn't detect all the defects or that incurs cost and schedule overruns. To conduct test

  16. Capacity, delay and mobility in wireless ad-hoc networks

    NARCIS (Netherlands)

    Bansal, N.; Liu, Z.

    2003-01-01

    Network throughput and packet delay are two important parameters in the design and the evaluation of routing protocols for ad-hoc networks. While mobility has been shown to increase the capacity of a network, it is not clear whether the delay can be kept low without trading off the throughput. We

  17. Analisis Unjuk Kerja Aplikasi VoIP Call Android di Jaringan MANET [Performance Analysis of VoIP Call Application Android in MANET (Mobile Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Ryan Ari Setyawan

    2015-06-01

    Full Text Available Penelitian ini bertujuan menganalisis kinerja aplikasi  VoIP call android di jaringan MANET (mobile ad hoc network.  Hasil pengujian menunjukan bahwa aplikasi VoIP call android dapat digunakan di jaringan MANET. Delay yang dihasilkan paling besar di pengujian indoor dengan jarak 11-15 meter yakni sebesar 0,014624811 seconds. Packet loss yang dihasilkan pada range 1%-2% sedangkan standar packet loss yang ditetapkan oleh CISCO untuk layanan aplikasi VoIP adalah < 5%. Jitter yang dihasilkan yakni antara 0,01-0,06 seconds sedangkan standar yang ditetapkan oleh CISCO adalah ≤ 30 ms atau 0,03 seconds. Throughput yang dihasilkan pada proses pengujian yakni antar 161 kbps-481 kbps. *****This study aims to analyze the performance of VOIP call android application in the MANET (mobile ad hoc network. The results showed that VoIP applications could be implemented in MANET network. The highest  delay is produced in indoor testing  with distance of 11-15 meters,  which is equal to 0.014624811 seconds. Packet loss is generated in the range of 1% -2%, while packet loss standards set by Cisco for VoIP application services are <5%. The jitter is between 0.01 to 0.06 seconds, while the standard set by CISCO is ≤ 30 ms or 0.03 seconds. Throughput generated in the testing process is between 161 kbps-481 kbps.

  18. Validation test case generation based on safety analysis ontology

    International Nuclear Information System (INIS)

    Fan, Chin-Feng; Wang, Wen-Shing

    2012-01-01

    Highlights: ► Current practice in validation test case generation for nuclear system is mainly ad hoc. ► This study designs a systematic approach to generate validation test cases from a Safety Analysis Report. ► It is based on a domain-specific ontology. ► Test coverage criteria have been defined and satisfied. ► A computerized toolset has been implemented to assist the proposed approach. - Abstract: Validation tests in the current nuclear industry practice are typically performed in an ad hoc fashion. This study presents a systematic and objective method of generating validation test cases from a Safety Analysis Report (SAR). A domain-specific ontology was designed and used to mark up a SAR; relevant information was then extracted from the marked-up document for use in automatically generating validation test cases that satisfy the proposed test coverage criteria; namely, single parameter coverage, use case coverage, abnormal condition coverage, and scenario coverage. The novelty of this technique is its systematic rather than ad hoc test case generation from a SAR to achieve high test coverage.

  19. Unmanned Aerial ad Hoc Networks: Simulation-Based Evaluation of Entity Mobility Models’ Impact on Routing Performance

    Directory of Open Access Journals (Sweden)

    Jean-Daniel Medjo Me Biomo

    2015-06-01

    Full Text Available An unmanned aerial ad hoc network (UAANET is a special type of mobile ad hoc network (MANET. For these networks, researchers rely mostly on simulations to evaluate their proposed networking protocols. Hence, it is of great importance that the simulation environment of a UAANET replicates as much as possible the reality of UAVs. One major component of that environment is the movement pattern of the UAVs. This means that the mobility model used in simulations has to be thoroughly understood in terms of its impact on the performance of the network. In this paper, we investigate how mobility models affect the performance of UAANET in simulations in order to come up with conclusions/recommendations that provide a benchmark for future UAANET simulations. To that end, we first propose a few metrics to evaluate the mobility models. Then, we present five random entity mobility models that allow nodes to move almost freely and independently from one another and evaluate four carefully-chosen MANET/UAANET routing protocols: ad hoc on-demand distance vector (AODV, optimized link state routing (OLSR, reactive-geographic hybrid routing (RGR and geographic routing protocol (GRP. In addition, flooding is also evaluated. The results show a wide variation of the protocol performance over different mobility models. These performance differences can be explained by the mobility model characteristics, and we discuss these effects. The results of our analysis show that: (i the enhanced Gauss–Markov (EGM mobility model is best suited for UAANET; (ii OLSR, a table-driven proactive routing protocol, and GRP, a position-based geographic protocol, are the protocols most sensitive to the change of mobility models; (iii RGR, a reactive-geographic hybrid routing protocol, is best suited for UAANET.

  20. On-Demand Routing in Multi-hop Wireless Mobile Ad Hoc Networks

    National Research Council Canada - National Science Library

    Maltz, David A

    2001-01-01

    .... Routing protocols used in ad hoc networks must automatically adjust to environments that can vary between the extremes of high mobility with low bandwidth, and low mobility with high bandwidth...

  1. Throughput and Fairness of Collision Avoidance Protocols in Ad Hoc Networks

    National Research Council Canada - National Science Library

    Garcia-Luna-Aceves, J. J; Wang, Yu

    2004-01-01

    .... In Section 1, The authors present an analytical modeling to derive the saturation throughput of these sender-initiated collision avoidance protocols in multi-hop ad hoc networks with nodes randomly...

  2. PNNI routing support for ad hoc mobile networking: The multilevel case

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, L.; Sholander, P.; Tolendino, L.

    1998-01-01

    This contribution extends the Outside Nodal Hierarchy List (ONHL) procedures described in ATM Forum Contributions 97-0766 and 97-0933. These extensions allow multiple mobile networks to form either an ad hoc network or an extension of a fixed PNNI infrastructure. A previous contribution (97-1073) covered the simplest case where the top-most Logical Group Nodes (LGNs), in those mobile networks, all resided at the same level in a PNNI hierarchy. This contribution covers the more general case wherein those top-most LGNs may reside at different PNNI hierarchy levels. Both of the SNL contributions consider flat ad hoc network architectures in the sense that each mobile network always participates in the PNNI hierarchy at the pre-configured level of its top-most LGN.

  3. ENERGY EFFICIENT ROUTING PROTOCOLS FOR WIRELESS AD HOC NETWORKS – A SURVEY

    Directory of Open Access Journals (Sweden)

    K. Sankar

    2012-06-01

    Full Text Available Reducing energy consumption, primarily with the goal of extending the lifetime of battery-powered devices, has emerged as a fundamental challenge in wireless communication. The performance of the medium access control (MAC scheme not only has a fairly significant end-result on the behaviour of the routing approach employed, but also on the energy consumption of the wireless network interface card (NIC. We investigate the inadequacies of the MAC schemes designed for ad hoc wireless networks in the context of power awareness herein. The topology changes due to uncontrollable factors such as node mobility, weather, interference, noise, as well as on controllable parameters such as transmission power and antenna direction results in significant amount of energy loss. Controlling rapid topology changes by minimizing the maximum transmission power used in ad hoc wireless networks, while still maintaining networks connectivity can prolong battery life and hence network lifetime considerably. In addition, we systematically explore the potential energy consumption pitfalls of non–power-based and power based routing schemes. We suggest a thorough energy-based performance survey of energy aware routing protocols for wireless mobile ad-hoc networks. We also present the statistical performance metrics measured by our simulations.

  4. Exploiting Mobile Ad Hoc Networking and Knowledge Generation to Achieve Ambient Intelligence

    Directory of Open Access Journals (Sweden)

    Anna Lekova

    2012-01-01

    Full Text Available Ambient Intelligence (AmI joins together the fields of ubiquitous computing and communications, context awareness, and intelligent user interfaces. Energy, fault-tolerance, and mobility are newly added dimensions of AmI. Within the context of AmI the concept of mobile ad hoc networks (MANETs for “anytime and anywhere” is likely to play larger roles in the future in which people are surrounded and supported by small context-aware, cooperative, and nonobtrusive devices that will aid our everyday life. The connection between knowledge generation and communication ad hoc networking is symbiotic—knowledge generation utilizes ad hoc networking to perform their communication needs, and MANETs will utilize the knowledge generation to enhance their network services. The contribution of the present study is a distributed evolving fuzzy modeling framework (EFMF to observe and categorize relationships and activities in the user and application level and based on that social context to take intelligent decisions about MANETs service management. EFMF employs unsupervised online one-pass fuzzy clustering method to recognize nodes' mobility context from social scenario traces and ubiquitously learn “friends” and “strangers” indirectly and anonymously.

  5. Performance analysis and implementation of proposed mechanism for detection and prevention of security attacks in routing protocols of vehicular ad-hoc network (VANET

    Directory of Open Access Journals (Sweden)

    Parul Tyagi

    2017-07-01

    Full Text Available Next-generation communication networks have become widely popular as ad-hoc networks, broadly categorized as the mobile nodes based on mobile ad-hoc networks (MANET and the vehicular nodes based vehicular ad-hoc networks (VANET. VANET is aimed at maintaining safety to vehicle drivers by begin autonomous communication with the nearby vehicles. Each vehicle in the ad-hoc network performs as an intelligent mobile node characterized by high mobility and formation of dynamic networks. The ad-hoc networks are decentralized dynamic networks that need efficient and secure communication requirements due to the vehicles being persistently in motion. These networks are more susceptible to various attacks like Warm Hole attacks, denial of service attacks and Black Hole Attacks. The paper is a novel attempt to examine and investigate the security features of the routing protocols in VANET, applicability of AODV (Ad hoc On Demand protocol to detect and tackle a particular category of network attacks, known as the Black Hole Attacks. A new algorithm is proposed to enhance the security mechanism of AODV protocol and to introduce a mechanism to detect Black Hole Attacks and to prevent the network from such attacks in which source node stores all route replies in a look up table. This table stores the sequences of all route reply, arranged in ascending order using PUSH and POP operations. The priority is calculated based on sequence number and discard the RREP having presumably very high destination sequence number. The result show that proposed algorithm for detection and prevention of Black Hole Attack increases security in Intelligent Transportation System (ITS and reduces the effect of malicious node in the VANET. NCTUNs simulator is used in this research work.

  6. An ad-hoc fretting wear tribotester design for thin steel wires

    Directory of Open Access Journals (Sweden)

    Llavori Iñigo

    2018-01-01

    Full Text Available Steel wire ropes experience fretting wear damage when the rope runs over a sheave promoting an oscillatory motion between the wires. Consequently, wear scars appear between the contacting wires leading to an increase of the stress field and the following rupture of the wires due to fatigue. That is why the understanding and prediction of the fretting wear phenomena of thin wires is fundamental in order to improve the performance of steel wire ropes. The present research deals with the design of an ad-hoc fretting wear test machine for thin wires. The test apparatus is designed for testing thin wires with a maximum diameter of 1.0 mm, at slip amplitudes ranging from 5 to 300 μm, crossing angle between 0-90°, and contacting force ranging from 0,5 to 5 N. The working principle of displacement amplitude and contacting force as well as the crossing angle between the wires are described. Preliminary studies for understanding the fretting wear characteristics are presented, analysing 0.45 mm diameter cold-drawn eutectoid carbon steel (0.8% C wires (tensile strength higher than 3000 MPa.

  7. Improving TCP Performance over Wireless Ad Hoc Networks with Busy Tone Assisted Scheme

    Directory of Open Access Journals (Sweden)

    Cai Lin

    2006-01-01

    Full Text Available It is well known that transmission control protocol (TCP performance degrades severely in IEEE 802.11-based wireless ad hoc networks. We first identify two critical issues leading to the TCP performance degradation: (1 unreliable broadcast, since broadcast frames are transmitted without the request-to-send and clear-to-send (RTS/CTS dialog and Data/ACK handshake, so they are vulnerable to the hidden terminal problem; and (2 false link failure which occurs when a node cannot successfully transmit data temporarily due to medium contention. We then propose a scheme to use a narrow-bandwidth, out-of-band busy tone channel to make reservation for broadcast and link error detection frames only. The proposed scheme is simple and power efficient, because only the sender needs to transmit two short messages in the busy tone channel before sending broadcast or link error detection frames in the data channel. Analytical results show that the proposed scheme can dramatically reduce the collision probability of broadcast and link error detection frames. Extensive simulations with different network topologies further demonstrate that the proposed scheme can improve TCP throughput by 23% to 150%, depending on user mobility, and effectively enhance both short-term and long-term fairness among coexisting TCP flows in multihop wireless ad hoc networks.

  8. Car-to-Pedestrian Communication Safety System Based on the Vehicular Ad-Hoc Network Environment: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Peng Jing

    2017-10-01

    Full Text Available With the unparalleled growth of motor vehicles, traffic accident between pedestrians and vehicles is one of the most serious issues in the word-wild. Plenty of injuries and fatalities are caused by the traffic accidents and crashes. The connected vehicular ad hoc network as an emerging approach which has the potential to reduce and even avoid accidents have been focused on by many researchers. A large number of car-to-pedestrian communication safety systems based on the vehicular ad hoc network are researching and developing. However, to our limited knowledge, a systematic review about the car-to-pedestrian communication safety system based on the vehicular ad-hoc network has not be written. The purpose and goal of this review is to systematically evaluate and access the reliability of car-to-pedestrian communication safety system based on the vehicular ad-hoc network environment and provide some recommendations for the future works according to throwing some light on the previous literatures. A quality evaluation was developed through established items and instruments tailored to this review. Future works are needed to focus on developing a valid as well as effective communication safety system based on the vehicular ad hoc network to protect the vulnerable road users.

  9. Studies on urban vehicular ad-hoc networks

    CERN Document Server

    Zhu, Hongzi

    2013-01-01

    With the advancement of wireless technology, vehicular ad hoc networks (VANETs) are emerging as a promising approach to realizing 'smart cities' and addressing many important transportation problems such as road safety, efficiency, and convenience.This brief provides an introduction to the large trace data set collected from thousands of taxis and buses in Shanghai, the largest metropolis in China. It also presents the challenges, design issues, performance modeling and evaluation of a wide spectrum of VANET research topics, ranging from realistic vehicular mobility models and opportunistic ro

  10. Limonene hydroperoxide analogues show specific patch test reactions.

    Science.gov (United States)

    Christensson, Johanna Bråred; Hellsén, Staffan; Börje, Anna; Karlberg, Ann-Therese

    2014-05-01

    The fragrance terpene R-limonene is a very weak sensitizer, but forms allergenic oxidation products upon contact with air. The primary oxidation products of oxidized limonene, the hydroperoxides, have an important impact on the sensitizing potency of the oxidation mixture. One analogue, limonene-1-hydroperoxide, was experimentally shown to be a significantly more potent sensitizer than limonene-2-hydroperoxide in the local lymph node assay with non-pooled lymph nodes. To investigate the pattern of reactivity among consecutive dermatitis patients to two structurally closely related limonene hydroperoxides, limonene-1-hydroperoxide and limonene-2-hydroperoxide. Limonene-1-hydroperoxide, limonene-2-hydroperoxide, at 0.5% in petrolatum, and oxidized limonene 3.0% pet. were tested in 763 consecutive dermatitis patients. Of the tested materials, limonene-1-hydroperoxide gave most reactions, with 2.4% of the patients showing positive patch test reactions. Limonene-2-hydroperoxide and oxidized R-limonene gave 1.7% and 1.2% positive patch test reactions, respectively. Concomitant positive patch test reactions to other fragrance markers in the baseline series were frequently noted. The results are in accordance with the experimental studies, as limonene-1-hydroperoxide gave more positive patch test reactions in the tested patients than limonene-2-hydroperoxide. Furthermore, the results support the specificity of the allergenic activity of the limonene hydroperoxide analogues and the importance of oxidized limonene as a cause of contact allergy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. TMAP ad hoc Working Group Fish Progress report 2007

    NARCIS (Netherlands)

    Bolle, L.J.; Damm, U.; Diederichs, B.; Jager, Z.; Overzee, van H.M.J.

    2007-01-01

    Building on previous work done by the TMAP ad hoc Working Group Fish, a meeting and a workshop were held in Hamburg in June and October 2007. The most important aim of both was to come to an agreement on how to proceed with the data preparations and analyses, and to facilitate the exchange of data

  12. Optimal design of cluster-based ad-hoc networks using probabilistic solution discovery

    International Nuclear Information System (INIS)

    Cook, Jason L.; Ramirez-Marquez, Jose Emmanuel

    2009-01-01

    The reliability of ad-hoc networks is gaining popularity in two areas: as a topic of academic interest and as a key performance parameter for defense systems employing this type of network. The ad-hoc network is dynamic and scalable and these descriptions are what attract its users. However, these descriptions are also synonymous for undefined and unpredictable when considering the impacts to the reliability of the system. The configuration of an ad-hoc network changes continuously and this fact implies that no single mathematical expression or graphical depiction can describe the system reliability-wise. Previous research has used mobility and stochastic models to address this challenge successfully. In this paper, the authors leverage the stochastic approach and build upon it a probabilistic solution discovery (PSD) algorithm to optimize the topology for a cluster-based mobile ad-hoc wireless network (MAWN). Specifically, the membership of nodes within the back-bone network or networks will be assigned in such as way as to maximize reliability subject to a constraint on cost. The constraint may also be considered as a non-monetary cost, such as weight, volume, power, or the like. When a cost is assigned to each component, a maximum cost threshold is assigned to the network, and the method is run; the result is an optimized allocation of the radios enabling back-bone network(s) to provide the most reliable network possible without exceeding the allowable cost. The method is intended for use directly as part of the architectural design process of a cluster-based MAWN to efficiently determine an optimal or near-optimal design solution. It is capable of optimizing the topology based upon all-terminal reliability (ATR), all-operating terminal reliability (AoTR), or two-terminal reliability (2TR)

  13. A Hybrid Energy Efficient Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Niranjan Kumar Ray

    2016-01-01

    Full Text Available We proposed an energy conservation technique called Location Based Topology Control with Sleep Scheduling for ad hoc networks. It uses the feature of both topology control approach and power management approach. Like the topology control approach, it attempts to reduce the transmission power of a node, which is determined from its neighborhood location information. A node goes to sleep state based on the traffic condition as that of power management approach. In the proposed scheme, a node goes to sleep state only when its absence does not create local partition in its neighborhood. We preformed extensive simulation to compare the proposed scheme with existing ones. Simulation results show that the energy consumption is lower with increase in the network lifetime and higher throughput in the proposed scheme.

  14. Secure Adaptive Topology Control for Wireless Ad-Hoc Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yen-Chieh Ouyang

    2010-02-01

    Full Text Available This paper presents a secure decentralized clustering algorithm for wireless ad-hoc sensor networks. The algorithm operates without a centralized controller, operates asynchronously, and does not require that the location of the sensors be known a priori. Based on the cluster-based topology, secure hierarchical communication protocols and dynamic quarantine strategies are introduced to defend against spam attacks, since this type of attacks can exhaust the energy of sensor nodes and will shorten the lifetime of a sensor network drastically. By adjusting the threshold of infected percentage of the cluster coverage, our scheme can dynamically coordinate the proportion of the quarantine region and adaptively achieve the cluster control and the neighborhood control of attacks. Simulation results show that the proposed approach is feasible and cost effective for wireless sensor networks.

  15. An Ad-Hoc Adaptive Pilot Model for Pitch Axis Gross Acquisition Tasks

    Science.gov (United States)

    Hanson, Curtis E.

    2012-01-01

    An ad-hoc algorithm is presented for real-time adaptation of the well-known crossover pilot model and applied to pitch axis gross acquisition tasks in a generic fighter aircraft. Off-line tuning of the crossover model to human pilot data gathered in a fixed-based high fidelity simulation is first accomplished for a series of changes in aircraft dynamics to provide expected values for model parameters. It is shown that in most cases, for this application, the traditional crossover model can be reduced to a gain and a time delay. The ad-hoc adaptive pilot gain algorithm is shown to have desirable convergence properties for most types of changes in aircraft dynamics.

  16. The Ad Hoc process to strengthen the framework convention on climate change

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishna, K.; Deutz, A.M.; Jacobsen, L.A. [eds.

    1995-11-01

    The Woods Hole Research Center convened an International Conference on The Ad Hoc Process to Strengthen the Framework Convention on Climate Change in Woods Hole, MA, on October 7-9, 1995. The conference was conducted to examine the prospects for successful adoption of a protocol to the Framework Convention on Climate Change by 1997. In preparation for the Second session of the Ad Hoc Group on the Berlin Mandate, several governmental and nongovernmental representatives met in Woods Hole to discuss the process and possible outcome of the Berlin Mandate negotiations for a protocol or other legal instrument to strengthen the Convention. The conference was by invitation and all participants attended in their personal capacities.

  17. ON SECURE FULL DUPLEX COMMUNICATION IN MOBILE AD HOC NETWORK

    OpenAIRE

    S. C. Dutta; Sudha Singh; D. K. Singh

    2013-01-01

    This paper is to establish Ad Hoc network in mobile phones and start fully secured full duplex communication in any situation. This type of communication will be cost effective and it will be fastest way of communication in case of any server failure or server error.

  18. An Economic Framework for Resource Allocation in Ad-hoc Grids

    NARCIS (Netherlands)

    Pourebrahimi, B.

    2009-01-01

    In this dissertation, we present an economic framework to study and develop different market-based mechanisms for resource allocation in an ad-hoc Grid. Such an economic framework helps to understand the impact of certain choices and explores what are the suitable mechanisms from Grid user/owner

  19. Capacity of Wireless Ad Hoc Networks with Opportunistic Collaborative Communications

    Directory of Open Access Journals (Sweden)

    Simeone O

    2007-01-01

    Full Text Available Optimal multihop routing in ad hoc networks requires the exchange of control messages at the MAC and network layer in order to set up the (centralized optimization problem. Distributed opportunistic space-time collaboration (OST is a valid alternative that avoids this drawback by enabling opportunistic cooperation with the source at the physical layer. In this paper, the performance of OST is investigated. It is shown analytically that opportunistic collaboration outperforms (centralized optimal multihop in case spatial reuse (i.e., the simultaneous transmission of more than one data stream is not allowed by the transmission protocol. Conversely, in case spatial reuse is possible, the relative performance between the two protocols has to be studied case by case in terms of the corresponding capacity regions, given the topology and the physical parameters of network at hand. Simulation results confirm that opportunistic collaborative communication is a promising paradigm for wireless ad hoc networks that deserves further investigation.

  20. Capacity of Wireless Ad Hoc Networks with Opportunistic Collaborative Communications

    Directory of Open Access Journals (Sweden)

    O. Simeone

    2007-03-01

    Full Text Available Optimal multihop routing in ad hoc networks requires the exchange of control messages at the MAC and network layer in order to set up the (centralized optimization problem. Distributed opportunistic space-time collaboration (OST is a valid alternative that avoids this drawback by enabling opportunistic cooperation with the source at the physical layer. In this paper, the performance of OST is investigated. It is shown analytically that opportunistic collaboration outperforms (centralized optimal multihop in case spatial reuse (i.e., the simultaneous transmission of more than one data stream is not allowed by the transmission protocol. Conversely, in case spatial reuse is possible, the relative performance between the two protocols has to be studied case by case in terms of the corresponding capacity regions, given the topology and the physical parameters of network at hand. Simulation results confirm that opportunistic collaborative communication is a promising paradigm for wireless ad hoc networks that deserves further investigation.

  1. An Effective Approach for Mobile ad hoc Network via I-Watchdog Protocol

    Directory of Open Access Journals (Sweden)

    Nidhi Lal

    2014-12-01

    Full Text Available Mobile ad hoc network (MANET is now days become very famous due to their fixed infrastructure-less quality and dynamic nature. They contain a large number of nodes which are connected and communicated to each other in wireless nature. Mobile ad hoc network is a wireless technology that contains high mobility of nodes and does not depend on the background administrator for central authority, because they do not contain any infrastructure. Nodes of the MANET use radio wave for communication and having limited resources and limited computational power. The Topology of this network is changing very frequently because they are distributed in nature and self-configurable. Due to its wireless nature and lack of any central authority in the background, Mobile ad hoc networks are always vulnerable to some security issues and performance issues. The security imposes a huge impact on the performance of any network. Some of the security issues are black hole attack, flooding, wormhole attack etc. In this paper, we will discuss issues regarding low performance of Watchdog protocol used in the MANET and proposed an improved Watchdog mechanism, which is called by I-Watchdog protocol that overcomes the limitations of Watchdog protocol and gives high performance in terms of throughput, delay.

  2. Novel store–carry–forward scheme for message dissemination in vehicular ad-hoc networks

    Directory of Open Access Journals (Sweden)

    Truc D.T. Nguyen

    2017-12-01

    Full Text Available To improve traffic safety in intelligent transportation systems, vehicles formed by vehicular ad-hoc networks (VANETs conventionally disseminate warning messages to their nearby vehicles as soon as a dangerous situation occurs. In this paper, we propose a novel scheme employing a novel story–carry–forward (SCF mechanism to tackle the network partition and broadcast storm problems, which are two major challenges in VANETs. The experimental result in the Veins simulation framework shows that the proposed SCF scheme significantly mitigates broadcast storms relative to other schemes, and maintains good coverage across various traffic densities.

  3. Report of the evaluation by the Ad Hoc Review Committee on Health Physics. Result evaluation in fiscal year 2000

    International Nuclear Information System (INIS)

    2001-06-01

    The Research Evaluation Committee, which consisted of 14 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Health Physics in accordance with the 'Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the R and D accomplishments achieved for five years from Fiscal Year 1995 to Fiscal Year 1999 at Department of Health Physics in Tokai Research Establishment and at related departments in other Establishments of JAERI. The Ad Hoc Review Committee consisted of six specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from October 2000 to January 2001. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on October 10, 2000, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on March 16, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on Health Physics. (author)

  4. Ad Hoc Transient Groups: Instruments for Awareness in Learning Networks

    NARCIS (Netherlands)

    Fetter, Sibren; Rajagopal, Kamakshi; Berlanga, Adriana; Sloep, Peter

    2011-01-01

    Fetter, S., Rajagopal, K., Berlanga, A. J., & Sloep, P. B. (2011). Ad Hoc Transient Groups: Instruments for Awareness in Learning Networks. In W. Reinhardt, T. D. Ullmann, P. Scott, V. Pammer, O. Conlan, & A. J. Berlanga (Eds.), Proceedings of the 1st European Workshop on Awareness and Reflection in

  5. Signaling-Free Max-Min Airtime Fairness in IEEE 802.11 Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Youngsoo Lee

    2016-01-01

    Full Text Available We propose a novel media access control (MAC protocol, referred to as signaling-free max-min airtime fair (SMAF MAC, to improve fairness and channel utilization in ad hoc networks based on IEEE 802.11 wireless local area networks (WLANs. We introduce busy time ratio (BTR as a measure for max-min airtime fairness. Each node estimates its BTR and adjusts the transmission duration by means of frame aggregation and fragmentation, so that it can implicitly announce the BTR to neighbor nodes. Based on the announced BTR, each of the neighbor nodes controls its contention window. In this way, the SMAF MAC works in a distributed manner without the need to know the max-min fair share of airtime, and it does not require exchanging explicit control messages among nodes to attain fairness. Moreover, we successfully incorporate the hidden node detection and resolution mechanisms into the SMAF MAC to deal with the hidden node problem in ad hoc networks. The simulation results confirm that the SMAF MAC enhances airtime fairness without degrading channel utilization, and it effectively resolves several serious problems in ad hoc networks such as the starvation, performance anomaly, and hidden node problems.

  6. Multicasting in Wireless Communications (Ad-Hoc Networks): Comparison against a Tree-Based Approach

    Science.gov (United States)

    Rizos, G. E.; Vasiliadis, D. C.

    2007-12-01

    We examine on-demand multicasting in ad hoc networks. The Core Assisted Mesh Protocol (CAMP) is a well-known protocol for multicast routing in ad-hoc networks, generalizing the notion of core-based trees employed for internet multicasting into multicast meshes that have much richer connectivity than trees. On the other hand, wireless tree-based multicast routing protocols use much simpler structures for determining route paths, using only parent-child relationships. In this work, we compare the performance of the CAMP protocol against the performance of wireless tree-based multicast routing protocols, in terms of two important factors, namely packet delay and ratio of dropped packets.

  7. Energy Efficient Probabilistic Broadcasting for Mobile Ad-Hoc Network

    Science.gov (United States)

    Kumar, Sumit; Mehfuz, Shabana

    2017-06-01

    In mobile ad-hoc network (MANETs) flooding method is used for broadcasting route request (RREQ) packet from one node to another node for route discovery. This is the simplest method of broadcasting of RREQ packets but it often results in broadcast storm problem, originating collisions and congestion of packets in the network. A probabilistic broadcasting is one of the widely used broadcasting scheme for route discovery in MANETs and provides solution for broadcasting storm problem. But it does not consider limited energy of the battery of the nodes. In this paper, a new energy efficient probabilistic broadcasting (EEPB) is proposed in which probability of broadcasting RREQs is calculated with respect to remaining energy of nodes. The analysis of simulation results clearly indicate that an EEPB route discovery scheme in ad-hoc on demand distance vector (AODV) can increase the network lifetime with a decrease in the average power consumption and RREQ packet overhead. It also decreases the number of dropped packets in the network, in comparison to other EEPB schemes like energy constraint gossip (ECG), energy aware gossip (EAG), energy based gossip (EBG) and network lifetime through energy efficient broadcast gossip (NEBG).

  8. Peer-to-peer over mobile ad hoc networks (Chapter 11)

    NARCIS (Netherlands)

    Qadri, N.N.; Liotta, A.; Pierre, S.

    2010-01-01

    In this chapter we review various approaches for the convergence of Peer-to-Peer (P2P) and Mobile Ad hoc Networks (MANETs), identifying strengths and weaknesses, and putting things in perspective. P2P and MANETs are among the most active research topics in pervasive computing. The convergence of P2P

  9. Intelligent Stale-Frame Discards for Real-Time Video Streaming over Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Sheu Tsang-Ling

    2009-01-01

    Full Text Available Abstract This paper presents intelligent early packet discards (I-EPD for real-time video streaming over a multihop wireless ad hoc network. In a multihop wireless ad hoc network, the quality of transferring real-time video streams could be seriously degraded, since every intermediate node (IN functionally like relay device does not possess large buffer and sufficient bandwidth. Even worse, a selected relay node could leave or power off unexpectedly, which breaks the route to destination. Thus, a stale video frame is useless even if it can reach destination after network traffic becomes smooth or failed route is reconfigured. In the proposed I-EPD, an IN can intelligently determine whether a buffered video packet should be early discarded. For the purpose of validation, we implement the I-EPD on Linux-based embedded systems. Via the comparisons of performance metrics (packet/frame discards ratios, PSNR, etc., we demonstrate that video quality over a wireless ad hoc network can be substantially improved and unnecessary bandwidth wastage is greatly reduced.

  10. A Protocol for Content-Based Communication in Disconnected Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Julien Haillot

    2010-01-01

    Full Text Available In content-based communication, information flows towards interested hosts rather than towards specifically set destinations. This new style of communication perfectly fits the needs of applications dedicated to information sharing, news distribution, service advertisement and discovery, etc. In this paper we address the problem of supporting content-based communication in partially or intermittently connected mobile ad hoc networks (MANETs. The protocol we designed leverages on the concepts of opportunistic networking and delay-tolerant networking in order to account for the absence of end-to-end connectivity in disconnected MANETs. The paper provides an overview of the protocol, as well as simulation results that show how this protocol can perform in realistic conditions.

  11. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    M. Isabel Vara

    2015-07-01

    Full Text Available Service discovery plays an important role in mobile ad hoc networks (MANETs. The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2. In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1. In order to advertise services, we have added a new type-length-value structure (TLV to the OLSRv2 protocol, called service discovery message (SDM, according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV protocol, in terms of service discovery ratio, service latency and network overhead.

  12. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks.

    Science.gov (United States)

    Vara, M Isabel; Campo, Celeste

    2015-07-20

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead.

  13. Context dependent off loading for cloudlet in mobile ad-hoc network

    Science.gov (United States)

    Bhatt, N.; Nadesh, R. K.; ArivuSelvan, K.

    2017-11-01

    Cloud Computing in Mobile Ad-hoc network is emerging part of research consideration as the demand and competency of mobile devices increased in last few years. To follow out operation within the remote cloud builds the postponement and influences the administration standard. To keep away from this trouble cloudlet is presented. Cloudlet gives identical support of the devices as cloud at low inactivity however at high transfer speed. Be that as it may, choice of a cloudlet for offloading calculation with flat energy is a noteworthy test if multiple cloud let is accessible adjacent. Here I proposed energy and bandwidth (Traffic overload for communication with cloud) aware cloudlet selection strategy based on the context dependency of the device location. It works on the basis of mobile device location and bandwidth availability of cloudlet. The cloudlet offloading and selection process using given solution is simulated in Cloud ~ Simulator.

  14. The accuracy of interpreting key psychiatric terms by ad hoc ...

    African Journals Online (AJOL)

    MacFarlane et al.15 note that a greater number of people have a preference for working with ad hoc interpreters in comparison to professional interpreters ... As part of a larger study, a cross-sectional qualitative interview design was used to ..... obstacle they would face if they would receive training. They had concerns over ...

  15. Autonomous Power Control MAC Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Battery energy limitation has become a performance bottleneck for mobile ad hoc networks. IEEE 802.11 has been adopted as the current standard MAC protocol for ad hoc networks. However, it was developed without considering energy efficiency. To solve this problem, many modifications on IEEE 802.11 to incorporate power control have been proposed in the literature. The main idea of these power control schemes is to use a maximum possible power level for transmitting RTS/CTS and the lowest acceptable power for sending DATA/ACK. However, these schemes may degrade network throughput and reduce the overall energy efficiency of the network. This paper proposes autonomous power control MAC protocol (APCMP, which allows mobile nodes dynamically adjusting power level for transmitting DATA/ACK according to the distances between the transmitter and its neighbors. In addition, the power level for transmitting RTS/CTS is also adjustable according to the power level for DATA/ACK packets. In this paper, the performance of APCMP protocol is evaluated by simulation and is compared with that of other protocols.

  16. Report of the evaluation by the Ad Hoc Review Committee on Information Technology. In-advance evaluation in fiscal year 2000

    International Nuclear Information System (INIS)

    2001-06-01

    The Research Evaluation Committee, which consisted of 14 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Information Technology in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the adequacy of the R and D programs pertaining to the establishment and utilization of the Information Technology Based Laboratory (ITBL) to be implemented for five years starting in Fiscal Year 2001 at Center for Promotion of Computational Science and Engineering and Department of Environmental Sciences of JAERI. The Ad Hoc Review Committee consisted of eight specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from February to March 2001. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on February 9, 2001, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on March 16, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on Information Technology. (author)

  17. Report of the evaluation by the Ad Hoc Review Committee on Nuclear Safety Research. Result evaluation in fiscal year 2000

    International Nuclear Information System (INIS)

    2001-06-01

    The Research Evaluation Committee, which consisted of 14 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Nuclear Safety Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the R and D accomplishments achieved for five years from Fiscal Year 1995 to Fiscal Year 1999 at Department of Reactor Safety Research, Department of Fuel Cycle Safety Research, Department of Environmental Safety Research and Department of Safety Research Technical Support in Tokai Research Establishment at JAERI. The Ad Hoc Review Committee consisted of 11 specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from December 2000 to February 2001. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on December 11, 2000, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on March 16, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on Nuclear Safety Research. (author)

  18. Performance Analysis of Hierarchical Group Key Management Integrated with Adaptive Intrusion Detection in Mobile ad hoc Networks

    Science.gov (United States)

    2016-04-05

    applications in wireless networks such as military battlefields, emergency response, mobile commerce , online gaming, and collaborative work are based on the...www.elsevier.com/locate/peva Performance analysis of hierarchical group key management integrated with adaptive intrusion detection in mobile ad hoc...Accepted 19 September 2010 Available online 26 September 2010 Keywords: Mobile ad hoc networks Intrusion detection Group communication systems Group

  19. Correctness-by-construction and post-hoc verification : a marriage of convenience?

    NARCIS (Netherlands)

    Watson, B.W.; Kourie, D.G.; Schaefer, I.; Cleophas, L.G.W.A.; Margaria, T.; Steffen, B.

    2016-01-01

    Correctness-by-construction (CbC), traditionally based on weakest precondition semantics, and post-hoc verification (PhV) aspire to ensure functional correctness. We argue for a lightweight approach to CbC where lack of formal rigour increases productivity. In order to mitigate the risk of

  20. Illustration, detection and prevention of sleep deprivation anomaly in mobile ad hoc networks

    International Nuclear Information System (INIS)

    Nadeem, A.; Ahsan, K.; Sarim, M.

    2017-01-01

    MANETs (Mobile Ad Hoc Networks) have applications in various walks of life from rescue operations to battle field operations, personal and commercial. However, routing operations in MANETs are still vulnerable to anomalies and DoS (Denial of Service) attacks such as sleep deprivation. In SD (Sleep Deprivation) attack malicious node exploits the vulnerability in the route discovery function of the reactive routing protocol for example AODV (Ad Hoc On-Demand Distance Vector). In this paper, we first illustrate the SD anomaly in MANETs and then propose a SD detection and prevention algorithm which efficiently deals with this attack. We assess the performance of our proposed approach through simulation, evaluating its successfulness using different network scenarios. (author)

  1. Position-Based Packet Forwarding for Vehicular Ad-Hoc Networks

    OpenAIRE

    Füßler, Holger

    2007-01-01

    Mobile Ad-Hoc Networks, or MANETs, are data communication networks between (potentially) mobile computer systems equipped with wireless communication devices and — in their purest form — in complete absence of communication infrastructure. Usage scenarios for these systems include communication during disaster recovery or battlefield communications. One of the great research challenges concerning MANETs is the Packet Forwarding Problem, i.e., the question to which neighbor node a data packet ...

  2. Protocols for Detection and Removal of Wormholes for Secure Routing and Neighborhood Creation in Wireless Ad Hoc Networks

    Science.gov (United States)

    Hayajneh, Thaier Saleh

    2009-01-01

    Wireless ad hoc networks are suitable and sometimes the only solution for several applications. Many applications, particularly those in military and critical civilian domains (such as battlefield surveillance and emergency rescue) require that ad hoc networks be secure and stable. In fact, security is one of the main barriers to the extensive use…

  3. Report of the evaluation by the Ad Hoc Review Committee on Materials Science Research. Ex-post evaluation in fiscal year 2003

    International Nuclear Information System (INIS)

    2004-06-01

    The Research Evaluation Committee, which consisted of 13 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Materials Science Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the adequacy of the R and D results achieved for five years until Fiscal Year 2002 at Department of Materials Science in Tokai Research Establishment of JAERI. The Ad Hoc Review Committee consisted of eight specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from October 2003 to February 2004. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on November 14, 2003, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on March 8, 2004. This report describes the result of the evaluation by the Ad Hoc Review Committee on Materials Science Research. (author)

  4. Report of the evaluation by the Ad Hoc Review Committee on Computational Science and Engineering. Result evaluation in fiscal year 2000

    International Nuclear Information System (INIS)

    2001-06-01

    The Research Evaluation Committee, which consisted of 14 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Computational Science and Engineering in accordance with the 'Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the R and D accomplishments achieved for five years from Fiscal Year 1995 to Fiscal Year 1999 at Center for Promotion of Computational Science and Engineering of JAERI. The Ad Hoc Review Committee consisted of seven specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from December 2000 to March 2001. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on December 27, 2000, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on March 16, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on Computational Science and Engineering. (author)

  5. Building Realistic Mobility Models for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Adrian Pullin

    2018-04-01

    Full Text Available A mobile ad hoc network (MANET is a self-configuring wireless network in which each node could act as a router, as well as a data source or sink. Its application areas include battlefields and vehicular and disaster areas. Many techniques applied to infrastructure-based networks are less effective in MANETs, with routing being a particular challenge. This paper presents a rigorous study into simulation techniques for evaluating routing solutions for MANETs with the aim of producing more realistic simulation models and thereby, more accurate protocol evaluations. MANET simulations require models that reflect the world in which the MANET is to operate. Much of the published research uses movement models, such as the random waypoint (RWP model, with arbitrary world sizes and node counts. This paper presents a technique for developing more realistic simulation models to test and evaluate MANET protocols. The technique is animation, which is applied to a realistic scenario to produce a model that accurately reflects the size and shape of the world, node count, movement patterns, and time period over which the MANET may operate. The animation technique has been used to develop a battlefield model based on established military tactics. Trace data has been used to build a model of maritime movements in the Irish Sea. Similar world models have been built using the random waypoint movement model for comparison. All models have been built using the ns-2 simulator. These models have been used to compare the performance of three routing protocols: dynamic source routing (DSR, destination-sequenced distance-vector routing (DSDV, and ad hoc n-demand distance vector routing (AODV. The findings reveal that protocol performance is dependent on the model used. In particular, it is shown that RWP models do not reflect the performance of these protocols under realistic circumstances, and protocol selection is subject to the scenario to which it is applied. To

  6. An Ad-Hoc Opportunistic Dissemination Protocol for Smartphone-based Participatory Traffic Monitoring

    NARCIS (Netherlands)

    Türkes, Okan; Seraj, Fatjon; Scholten, Johan; Meratnia, Nirvana; Havinga, Paul J.M.

    2015-01-01

    This study introduces an ad-hoc opportunistic data dissemination protocol, called VADISS, that facilitates participatory traffic monitoring applications with smartphones. As a ubiquitous alternative to existing vehicular networking methods, VADISS uses the default WiFi interfaces universally adopted

  7. Report of the evaluation by the Ad Hoc Review Committee on Nuclear Safety Research. Result evaluation in fiscal year 2000

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-06-01

    The Research Evaluation Committee, which consisted of 14 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Nuclear Safety Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the R and D accomplishments achieved for five years from Fiscal Year 1995 to Fiscal Year 1999 at Department of Reactor Safety Research, Department of Fuel Cycle Safety Research, Department of Environmental Safety Research and Department of Safety Research Technical Support in Tokai Research Establishment at JAERI. The Ad Hoc Review Committee consisted of 11 specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from December 2000 to February 2001. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on December 11, 2000, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on March 16, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on Nuclear Safety Research. (author)

  8. A multi-protocol framework for ad-hoc service discovery

    OpenAIRE

    Flores-Cortes, C.; Blair, Gordon S.; Grace, P.

    2006-01-01

    Discovering the appropriate services in ad-hoc computing environments where a great number of devices and software components collaborate discreetly and provide numerous services is an important challenge. Service discovery protocols make it possible for participating nodes in a network to locate and advertise services with minimum user intervention. However, because it is not possible to predict at design time which protocols will be used to advertise services in a given context/environment,...

  9. AUTHENTICATION ARCHITECTURE USING THRESHOLD CRYPTOGRAPHY IN KERBEROS FOR MOBILE AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    Hadj Gharib

    2014-06-01

    Full Text Available The use of wireless technologies is gradually increasing and risks related to the use of these technologies are considerable. Due to their dynamically changing topology and open environment without a centralized policy control of a traditional network, a mobile ad hoc network (MANET is vulnerable to the presence of malicious nodes and attacks. The ideal solution to overcome a myriad of security concerns in MANET’s is the use of reliable authentication architecture. In this paper we propose a new key management scheme based on threshold cryptography in kerberos for MANET’s, the proposed scheme uses the elliptic curve cryptography method that consumes fewer resources well adapted to the wireless environment. Our approach shows a strength and effectiveness against attacks.

  10. A LOOP-BASED APPROACH IN CLUSTERING AND ROUTING IN MOBILE AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Li Yanping; Wang Xin; Xue Xiangyang; C.K. Toh

    2006-01-01

    Although clustering is a convenient framework to enable traffic control and service support in Mobile Ad hoc NETworks (MANETs), it is seldom adopted in practice due to the additional traffic overhead it leads to for the resource limited ad hoc network. In order to address this problem, we proposed a loop-based approach to combine clustering and routing. By employing loop topologies, topology information is disseminated with a loop instead of a single node, which provides better robustness, and the nature of a loop that there are two paths between each pair of nodes within a loop suggests smart route recovery strategy. Our approach is composed of setup procedure, regular procedure and recovery procedure to achieve clustering, routing and emergent route recovering.

  11. Mobile ad hoc networking the cutting edge directions

    CERN Document Server

    Basagni, Stefano; Giordano, Silvia; Stojmenovic, Ivan

    2013-01-01

    ""An excellent book for those who are interested in learning the current status of research and development . . . [and] who want to get a comprehensive overview of the current state-of-the-art.""-E-Streams This book provides up-to-date information on research and development in the rapidly growing area of networks based on the multihop ad hoc networking paradigm. It reviews all classes of networks that have successfully adopted this paradigm, pointing out how they penetrated the mass market and sparked breakthrough research. Covering both physical issues and applica

  12. A Cross Layer Solution to Address TCP Intra-flow Performance Degradation in Multihop Ad hoc Networks

    OpenAIRE

    Rakocevic, V.; Hamadani, E.

    2008-01-01

    Incorporating the concept of TCP end-to-end congestion control for wireless networks is one of the primary concerns in designing ad hoc networks since TCP was primarily designed and optimized based on the assumptions for wired networks. In this study, our interest lies on tackling the TCP instability and in particular intra-flow instability problem since due to the nature of applications in multihop ad hoc networks, connection instability or starvation even for a short period of time can have...

  13. Adaptive Demand-Driven Multicast Routing in Multi-Hop Wireless Ad Hoc Networks

    National Research Council Canada - National Science Library

    Jetcheva, Jorjeta G

    2004-01-01

    ...) nodes that wish to communicate. Each node in the ad hoc network acts as a router and forwards packets on behalf of other nodes, allowing nodes that are not within wireless range of each other to communicate over multi-hop paths...

  14. Report of the evaluation by the Ad Hoc Review Committee on Materials Science Research. In-advance evaluation in fiscal year 2002

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-11-01

    The Research Evaluation Committee, which consisted of 13 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Materials Science Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the adequacy of the R and D programs to be implemented for five years starting in Fiscal Year 2003 at Department of Materials Science in Tokai Research Establishment of JAERI. The Ad Hoc Review Committee consisted of eight specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from April 2002 to August 2002. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on June 5th, 2002, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on August 5th, 2002. This report describes the result of the evaluation by the Ad Hoc Review Committee on Materials Science Research. (author)

  15. Report of the evaluation by the Ad Hoc Review Committee on Materials Science Research. In-advance evaluation in fiscal year 2002

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-11-01

    The Research Evaluation Committee, which consisted of 13 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Materials Science Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the adequacy of the R and D programs to be implemented for five years starting in Fiscal Year 2003 at Department of Materials Science in Tokai Research Establishment of JAERI. The Ad Hoc Review Committee consisted of eight specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from April 2002 to August 2002. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on June 5th, 2002, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on August 5th, 2002. This report describes the result of the evaluation by the Ad Hoc Review Committee on Materials Science Research. (author)

  16. Report of the evaluation by the ad hoc review committee on radiation application research. In-advance evaluation in fiscal year 2001

    International Nuclear Information System (INIS)

    2001-11-01

    The Research Evaluation Committee, which consisted of 13 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Radiation Application Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the adequacy of the R and D programs to be implemented for five years starting in Fiscal Year 2002 at Department of Material Development, at Department of Ion-Beam-Applied Biology and at Advanced Radiation Technology Center in Takasaki Radiation Chemistry Research Establishment of JAERI. The Ad Hoc Review Committee consisted of ten specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from May to July 2001. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on June 25, 2001, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on July 12, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on Radiation Application Research. (author)

  17. Ad-hoc Content-based Queries and Data Analysis for Virtual Observatories, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Aquilent, Inc. proposes to support ad-hoc, content-based query and data retrieval from virtual observatories (VxO) by developing 1) Higher Order Query Services that...

  18. Testing Applications in MANET Environments through Emulation

    Directory of Open Access Journals (Sweden)

    Pietro Manzoni

    2009-01-01

    Full Text Available Mobile Ad Hoc Network solution testing is typically done using simulation. The simulated code is generally a simplified version of the real code, and thus code porting to actual operating systems lacks a strong validation. In this work we present Castadiva, a test-bed architecture that allows validating software solutions for real ad hoc network environments using low-cost, off-the-shelf devices and open source software. Castadiva is also compatible with the ns-2 simulator, allowing a combined and more complete evaluation. In this work we present our tool and the results obtained when evaluating videocalls in different scenarios, both static and dynamic.

  19. Optimum Combining for Rapidly Fading Channels in Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Sonia Furman

    2003-10-01

    Full Text Available Research and technology in wireless communication systems such as radar and cellular networks have successfully implemented alternative design approaches that utilize antenna array techniques such as optimum combining, to mitigate the degradation effects of multipath in rapid fading channels. In ad hoc networks, these methods have not yet been exploited primarily due to the complexity inherent in the network's architecture. With the high demand for improved signal link quality, devices configured with omnidirectional antennas can no longer meet the growing need for link quality and spectrum efficiency. This study takes an empirical approach to determine an optimum combining antenna array based on 3 variants of interelement spacing. For rapid fading channels, the simulation results show that the performance in the network of devices retrofitted with our antenna arrays consistently exceeded those with an omnidirectional antenna. Further, with the optimum combiner, the performance increased by over 60% compared to that of an omnidirectional antenna in a rapid fading channel.

  20. Formal reconstruction of attack scenarios in mobile ad hoc and sensor networks

    Directory of Open Access Journals (Sweden)

    Rekhis Slim

    2011-01-01

    Full Text Available Abstract Several techniques of theoretical digital investigation are presented in the literature but most of them are unsuitable to cope with attacks in wireless networks, especially in Mobile Ad hoc and Sensor Networks (MASNets. In this article, we propose a formal approach for digital investigation of security attacks in wireless networks. We provide a model for describing attack scenarios in a wireless environment, and system and network evidence generated consequently. The use of formal approaches is motivated by the need to avoid ad hoc generation of results that impedes the accuracy of analysis and integrity of investigation. We develop an inference system that integrates the two types of evidence, handles incompleteness and duplication of information in them, and allows possible and provable actions and attack scenarios to be generated. To illustrate the proposal, we consider a case study dealing with the investigation of a remote buffer overflow attack.

  1. Modelling and Initial Validation of the DYMO Routing Protocol for Mobile Ad-Hoc Networks

    DEFF Research Database (Denmark)

    Espensen, Kristian Asbjørn Leth; Kjeldsen, Mads Keblov; Kristensen, Lars Michael

    2008-01-01

    A mobile ad-hoc network (MANET) is an infrastructureless network established by a set of mobile devices using wireless communication. The Dynamic MANET On-demand (DYMO) protocol is a routing protocol for multi-hop communication in MANETs currently under development by the Internet Engineering Task...... Force (IETF). This paper presents a Coloured Petri Net (CPN) model of the mandatory parts of the DYMO protocol, and shows how scenario-based state space exploration has been used to validate key properties of the protocol. Our CPN modelling and verification work has spanned two revisions of the DYMO...... protocol specification and have had direct impact on the most recent version of the protocol specification....

  2. Enhancing On-Demand Multicast Routing Protocols using Mobility Prediction in Mobile Ad-hoc Network

    Directory of Open Access Journals (Sweden)

    Nermin Makhlouf

    2014-08-01

    Full Text Available A Mobile Ad hoc Network (MANET is a self-organizing wireless communication network in which mobile devices are based on no infrastructure like base stations or access points. Minimal configuration and quick deployment make ad hoc networks suitable for emergency situations like disaster recovery or military conflict. Since node mobility may cause links to be broken frequently, a very important issue for routing in MANETs is how to set reliable paths which can last as long as possible. To solve this problem, non-random behaviors for the mobility patterns that mobile users exhibit are exploited. This paper introduces a scheme to improve On-Demand Multicast Routing Protocol (ODMRP performances by using mobility prediction. 

  3. Design of free patterns of nanocrystals with ad hoc features via templated dewetting

    Energy Technology Data Exchange (ETDEWEB)

    Aouassa, M.; Berbezier, I.; Favre, L.; Ronda, A. [IM2NP, CNRS, AMU, Marseille (France); Bollani, M.; Sordan, R. [LNES, Como (Italy); Delobbe, A.; Sudraud, P. [Orsay Physics, Fuveau (France)

    2012-07-02

    Design of monodisperse ultra-small nanocrystals (NCs) into large scale patterns with ad hoc features is demonstrated. The process makes use of solid state dewetting of a thin film templated through alloy liquid metal ion source focused ion beam (LMIS-FIB) nanopatterning. The solid state dewetting initiated at the edges of the patterns controllably creates the ordering of NCs with ad hoc placement and periodicity. The NC size is tuned by varying the nominal thickness of the film while their position results from the association of film retraction from the edges of the lay out and Rayleigh-like instability. The use of ultra-high resolution LMIS-FIB enables to produce monocrystalline NCs with size, periodicity, and placement tunable as well. It provides routes for the free design of nanostructures for generic applications in nanoelectronics.

  4. The impact of brief team communication, leadership and team behavior training on ad hoc team performance in trauma care settings.

    Science.gov (United States)

    Roberts, Nicole K; Williams, Reed G; Schwind, Cathy J; Sutyak, John A; McDowell, Christopher; Griffen, David; Wall, Jarrod; Sanfey, Hilary; Chestnut, Audra; Meier, Andreas H; Wohltmann, Christopher; Clark, Ted R; Wetter, Nathan

    2014-02-01

    Communication breakdowns and care coordination problems often cause preventable adverse patient care events, which can be especially acute in the trauma setting, in which ad hoc teams have little time for advanced planning. Existing teamwork curricula do not address the particular issues associated with ad hoc emergency teams providing trauma care. Ad hoc trauma teams completed a preinstruction simulated trauma encounter and were provided with instruction on appropriate team behaviors and team communication. Teams completed a postinstruction simulated trauma encounter immediately afterward and 3 weeks later, then completed a questionnaire. Blinded raters rated videotapes of the simulations. Participants expressed high levels of satisfaction and intent to change practice after the intervention. Participants changed teamwork and communication behavior on the posttest, and changes were sustained after a 3-week interval, though there was some loss of retention. Brief training exercises can change teamwork and communication behaviors on ad hoc trauma teams. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Report of the Ad Hoc Committee on SSC physics

    International Nuclear Information System (INIS)

    1990-04-01

    The Ad Hoc Committee on SSC Physics has reexamined the relationship between beam energy, machine luminosity, and physics capability. In the next section, the physics motivation for the SSC is reviewed in general terms. This is followed by a discussion of the ability to detect a number of specific processes as a function of the SSC energy and luminosity. The viability of various detector technologies is then assessed as a function of luminosity. The report ends with a brief summary and some conclusions

  6. Reliable Ant Colony Routing Algorithm for Dual-Channel Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    YongQiang Li

    2018-01-01

    Full Text Available For the problem of poor link reliability caused by high-speed dynamic changes and congestion owing to low network bandwidth in ad hoc networks, an ant colony routing algorithm, based on reliable path under dual-channel condition (DSAR, is proposed. First, dual-channel communication mode is used to improve network bandwidth, and a hierarchical network model is proposed to optimize the dual-layer network. Thus, we reduce network congestion and communication delay. Second, a comprehensive reliable path selection strategy is designed, and the reliable path is selected ahead of time to reduce the probability of routing restart. Finally, the ant colony algorithm is used to improve the adaptability of the routing algorithm to changes of network topology. Simulation results show that DSAR improves the reliability of routing, packet delivery, and throughput.

  7. Asymptotic Delay Analysis for Cross-Layer Delay-Based Routing in Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Philippe Jacquet

    2007-01-01

    Full Text Available This paper addresses the problem of the evaluation of the delay distribution via analytical means in IEEE 802.11 wireless ad hoc networks. We show that the asymptotic delay distribution can be expressed as a power law. Based on the latter result, we present a cross-layer delay estimation protocol and we derive new delay-distribution-based routing algorithms, which are well adapted to the QoS requirements of real-time multimedia applications. In fact, multimedia services are not sensitive to average delays, but rather to the asymptotic delay distributions. Indeed, video streaming applications drop frames when they are received beyond a delay threshold, determined by the buffer size. Although delay-distribution-based routing is an NP-hard problem, we show that it can be solved in polynomial time when the delay threshold is large, because of the asymptotic power law distribution of the link delays.

  8. Report of the evaluation by the Ad Hoc Review Committee on High-Temperature Engineering and Research. Result evaluation in fiscal year 2000

    International Nuclear Information System (INIS)

    2001-06-01

    The Research Evaluation Committee, which consisted of 14 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on High-Temperature Engineering and Research in accordance with the 'Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the R and D accomplishments achieved for five years from Fiscal Year 1995 to Fiscal Year 1999 at Department of HTTR Project and Department of Advanced Nuclear Heat Technology in Oarai Research Establishment of JAERI. The Ad Hoc Review Committee consisted of nine specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from December 2000 to February 2001. The evaluation was performed on the basis of the materials submitted in advanced and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on December 8, 2000, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on March 16, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on High-Temperature Engineering and Research. (author)

  9. Ad Hoc Transient Communities to Enhance Social Interaction and Spread Tutor Responsibilities

    NARCIS (Netherlands)

    Sloep, Peter; Kester, Liesbeth; Brouns, Francis; Van Rosmalen, Peter; De Vries, Fred; De Croock, Marcel; Koper, Rob

    2007-01-01

    Sloep, P.B., Kester, L., Brouns, F., Van Rosmalen, P., De Vries, F., De Croock, M., Koper, R. (2007). Ad Hoc Transient Communities to Enhance Social Interaction and Spread Tutor Responsibilities. Presentation given at the Sixth IASTED International Conference on Web-based Education, 14-16 March,

  10. A Survey on Trust Management for Mobile Ad Hoc Networks

    Science.gov (United States)

    2011-11-01

    expects, trust is dangerous implying the possible betrayal of trust. In his comments on Lagerspetz’s book titled Trust: The Tacit Demand, Lahno [24...AODV Zouridaki et al. (2005 ) [79] (2006) [80] Secure routing Direct observation [79][80] Reputation by secondhand information [80] Packet dropping...areas of signal processing, wireless communications, sensor and mobile ad hoc networks. He is co-editor of the book Wireless Sensor Networks: Signal

  11. Report of the Ad Hoc Committee on Test Beam Policy

    International Nuclear Information System (INIS)

    Stefanski, R.; Anderson, D.; Childress, S.

    1989-01-01

    This document was developed at the request of the Physics Advisory Committee of the Fermi National Accelerator Laboratory to review the general subject of test beams with the purpose of establishing general policy and guidelines for consideration of future test beam requests. The recommendations stated here should be subject to periodic review, since the Laboratory position must change as needs and available resources change

  12. On knowledge transfer management as a learning process for ad hoc teams

    Science.gov (United States)

    Iliescu, D.

    2017-08-01

    Knowledge management represents an emerging domain becoming more and more important. Concepts like knowledge codification and personalisation, knowledge life-cycle, social and technological dimensions, knowledge transfer and learning management are integral parts. Focus goes here in the process of knowledge transfer for the case of ad hoc teams. The social dimension of knowledge transfer plays an important role. No single individual actors involved in the process, but a collective one, representing the organisation. It is critically important for knowledge to be managed from the life-cycle point of view. A complex communication network needs to be in place to supports the process of knowledge transfer. Two particular concepts, the bridge tie and transactive memory, would eventually enhance the communication. The paper focuses on an informational communication platform supporting the collaborative work on knowledge transfer. The platform facilitates the creation of a topic language to be used in knowledge modelling, storage and reuse, by the ad hoc teams.

  13. BCDP: Budget Constrained and Delay-Bounded Placement for Hybrid Roadside Units in Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Peng Li

    2014-11-01

    Full Text Available In vehicular ad hoc networks, roadside units (RSUs placement has been proposed to improve the the overall network performance in many ITS applications. This paper addresses the budget constrained and delay-bounded placement problem (BCDP for roadside units in vehicular ad hoc networks. There are two types of RSUs: cable connected RSU (c-RSU and wireless RSU (w-RSU. c-RSUs are interconnected through wired lines, and they form the backbone of VANETs, while w-RSUs connect to other RSUs through wireless communication and serve as an economical extension of the coverage of c-RSUs. The delay-bounded coverage range and deployment cost of these two cases are totally different. We are given a budget constraint and a delay bound, the problem is how to find the optimal candidate sites with the maximal delay-bounded coverage to place RSUs such that a message from any c-RSU in the region can be disseminated to the more vehicles within the given budget constraint and delay bound. We first prove that the BCDP problem is NP-hard. Then we propose several algorithms to solve the BCDP problem. Simulation results show the heuristic algorithms can significantly improve the coverage range and reduce the total deployment cost, compared with other heuristic methods.

  14. Ad Hoc Transient Communities to Enhance Social Interaction and Spread Tutor Responsibilities

    NARCIS (Netherlands)

    Sloep, Peter; Kester, Liesbeth; Brouns, Francis; Van Rosmalen, Peter; De Vries, Fred; De Croock, Marcel; Koper, Rob

    2007-01-01

    Sloep, P.B., Kester, L. Brouns, F., Van Rosmalen, P., De Vries, F., De Croock, M., Koper, R. (2007) Ad Hoc Transient Communities to Enhance Social Interaction and Spread Tutor Responsibilities. In V. Uskov (Ed.) The Sixth IASTED International Conference on Web-based Education WBE 2007, March 14-16,

  15. A tandem queueing model for delay analysis in disconnected ad hoc networks

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; de Haan, Roland; Boucherie, Richardus J.; van Ommeren, Jan C.W.

    2007-01-01

    Ad hoc network routing protocols may fail to operate in the absence of an end-to-end connection from source to destination. This deficiency can be resolved by so-called opportunistic networking which exploits the mobility of the nodes by letting them operate as relays according to the

  16. Model-based prototyping of an interoperability protocol for mobile ad-hoc networks

    NARCIS (Netherlands)

    Kristensen, L.M.; Westergaard, M.; Norgaard, P.C.; Romijn, J.; Smith, G.; Pol, van de J.

    2005-01-01

    We present an industrial project conducted at Ericsson Danmark A/S, Telebit where formal methods in the form of Coloured Petri Nets (CP-nets or CPNs) have been used for the specification of an interoperability protocol for routing packets between fixed core networks and mobile ad-hoc networks. The

  17. Energy-aware architecture for multi-rate ad hoc networks

    Directory of Open Access Journals (Sweden)

    Ahmed Yahya

    2010-06-01

    Full Text Available The backbone of ad hoc network design is energy performance and bandwidth resources limitations. Multi-rate adaptation architectures have been proposed to reduce the control overhead and to increase bandwidth utilization efficiency. In this paper, we propose a multi-rate protocol to provide the highest network performance under very low control overhead. The efficiency of the proposed auto multi-rate protocol is validated extensive simulations using QualNet network simulator. The simulation results demonstrate that our solution significantly improves the overall network performance.

  18. Adjusting Sensing Range to Maximize Throughput on Ad-Hoc Multi-Hop Wireless Networks

    National Research Council Canada - National Science Library

    Roberts, Christopher

    2003-01-01

    .... Such a network is referred to as a multi-hop ad-hoc network, or simply a multi-hop network. Most multi-hop network protocols use some form of carrier sensing to determine if the wireless channel is in use...

  19. Energy-Aware Broadcasting and Multicasting in Wireless Ad Hoc Networks: A Cross-Layering Approach

    National Research Council Canada - National Science Library

    Wieselthier, Jeffrey E; Nguyen, Gam D; Ephremides, Anthony

    2004-01-01

    ...) problems, especially when energy-aware operation is required. To address the specific problem of energy-aware tree construction in wireless ad hoc networks, we have developed the Broadcast Incremental Power (BIP...

  20. Built-In Device Orientation Sensors for Ad-Hoc Pairing and Spatial Awareness

    DEFF Research Database (Denmark)

    Grønbæk, Jens Emil; O'Hara, Kenton

    Mobile devices are equipped with multiple sensors. The ubiquity of these sensors is key in their ability to support in-the-wild application and use. Building on the ubiquity we look at how we can use this existing sensing infrastructure combined with user mediation to support ad-hoc sharing with ...

  1. Impact of Mobility on the Performance of Relaying in Ad Hoc Networks

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Kherani, A.A.; Groenevelt, R.; Nain, P.; Altman, E

    2006-01-01

    We consider a mobile ad hoc network consisting of three types of nodes: source, destination, and relay nodes. All the nodes are moving over a bounded region with possibly different mobility patterns. We introduce and study the notion of relay throughput, i.e. the maximum rate at which a node can

  2. Improving the Usability of OCL as an Ad-hoc Model Querying Language

    DEFF Research Database (Denmark)

    Störrle, Harald

    2013-01-01

    from our research and make it accessible to the OCL community, we propose the OCL Query API (OQAPI), a library of query-predicates to improve the user-friendliness of OCL for ad-hoc querying. The usability of OQAPI is studied using controlled experiments. We nd considerable evidence to support our...

  3. Effects of memantine on cognition in patients with moderate to severe Alzheimer's disease: post-hoc analyses of ADAS-cog and SIB total and single-item scores from six randomized, double-blind, placebo-controlled studies.

    Science.gov (United States)

    Mecocci, Patrizia; Bladström, Anna; Stender, Karina

    2009-05-01

    The post-hoc analyses reported here evaluate the specific effects of memantine treatment on ADAS-cog single-items or SIB subscales for patients with moderate to severe AD. Data from six multicentre, randomised, placebo-controlled, parallel-group, double-blind, 6-month studies were used as the basis for these post-hoc analyses. All patients with a Mini-Mental State Examination (MMSE) score of less than 20 were included. Analyses of patients with moderate AD (MMSE: 10-19), evaluated with the Alzheimer's disease Assessment Scale (ADAS-cog) and analyses of patients with moderate to severe AD (MMSE: 3-14), evaluated using the Severe Impairment Battery (SIB), were performed separately. The mean change from baseline showed a significant benefit of memantine treatment on both the ADAS-cog (p ADAS-cog single-item analyses showed significant benefits of memantine treatment, compared to placebo, for mean change from baseline for commands (p < 0.001), ideational praxis (p < 0.05), orientation (p < 0.01), comprehension (p < 0.05), and remembering test instructions (p < 0.05) for observed cases (OC). The SIB subscale analyses showed significant benefits of memantine, compared to placebo, for mean change from baseline for language (p < 0.05), memory (p < 0.05), orientation (p < 0.01), praxis (p < 0.001), and visuospatial ability (p < 0.01) for OC. Memantine shows significant benefits on overall cognitive abilities as well as on specific key cognitive domains for patients with moderate to severe AD. (c) 2009 John Wiley & Sons, Ltd.

  4. RAILWAY INFRASTRUCTURE CAPACITY MANAGEMENT FOR AD-HOC TRAINS ON THE SŽDC NETWORK

    Directory of Open Access Journals (Sweden)

    Petr Nachtigall

    2016-09-01

    Full Text Available The paper describes basic principles of ad-hoc routes assignment. Each carrier has its own interface called information system KADR with SŽDC for capacity requests management. The paper describes all steps which must be done before train departure.

  5. An Approach to Ad-hoc Messaging Networks Using Time Shifted Propagation

    Directory of Open Access Journals (Sweden)

    Christoph Fuchß

    2007-10-01

    Full Text Available Many communication devices, like mobile phones and PDAs, are enabled for near field communication by using Bluetooth. Many approaches dealt so far with the attempt to transfer mobile ad-hoc networks (MANET to the mechanism of the “fixed internet” to mobile networks. In order to achieve liability and robustness of common TCP connections routing algorithm in near field communication based networks become more sophisticated and complex. These mechanisms often do not reflect on the application’s particularities.Our approach of an ad-hoc messaging network (AMNET uses simple store-and-forward message passing to spread data asynchronously. We do not aim at the reliability of common internet networks but focus on application specific needs that can be covered by simple message passing mechanism. In this paper we will portray a powerful network by using simple devices and communication protocols on the basis of AMNETs. Simulation results of our AMNET approach provide insights towards speeding up the network setup process and to enable the use of AMNETs even with few participants by introducing a hybrid structure of infrastructure and mobile nodes.

  6. Cross-layer model design in wireless ad hoc networks for the Internet of Things.

    Science.gov (United States)

    Yang, Xin; Wang, Ling; Xie, Jian; Zhang, Zhaolin

    2018-01-01

    Wireless ad hoc networks can experience extreme fluctuations in transmission traffic in the Internet of Things, which is widely used today. Currently, the most crucial issues requiring attention for wireless ad hoc networks are making the best use of low traffic periods, reducing congestion during high traffic periods, and improving transmission performance. To solve these problems, the present paper proposes a novel cross-layer transmission model based on decentralized coded caching in the physical layer and a content division multiplexing scheme in the media access control layer. Simulation results demonstrate that the proposed model effectively addresses these issues by substantially increasing the throughput and successful transmission rate compared to existing protocols without a negative influence on delay, particularly for large scale networks under conditions of highly contrasting high and low traffic periods.

  7. Cross-layer model design in wireless ad hoc networks for the Internet of Things.

    Directory of Open Access Journals (Sweden)

    Xin Yang

    Full Text Available Wireless ad hoc networks can experience extreme fluctuations in transmission traffic in the Internet of Things, which is widely used today. Currently, the most crucial issues requiring attention for wireless ad hoc networks are making the best use of low traffic periods, reducing congestion during high traffic periods, and improving transmission performance. To solve these problems, the present paper proposes a novel cross-layer transmission model based on decentralized coded caching in the physical layer and a content division multiplexing scheme in the media access control layer. Simulation results demonstrate that the proposed model effectively addresses these issues by substantially increasing the throughput and successful transmission rate compared to existing protocols without a negative influence on delay, particularly for large scale networks under conditions of highly contrasting high and low traffic periods.

  8. The post hoc use of randomised controlled trials to explore drug associated cancer outcomes

    DEFF Research Database (Denmark)

    Stefansdottir, Gudrun; Zoungas, Sophia; Chalmers, John

    2013-01-01

    on public health before proper regulatory action can be taken. This paper aims to discuss challenges of exploring drug-associated cancer outcomes by post-hoc analyses of Randomised controlled trials (RCTs) designed for other purposes. METHODOLOGICAL CHALLENGES TO CONSIDER: We set out to perform a post......-hoc nested case-control analysis in the ADVANCE trial in order to examine the association between insulin use and cancer. We encountered several methodological challenges that made the results difficult to interpret, including short duration of exposure of interest, lack of power, and correlation between...... exposure and potential confounders. Considering these challenges, we concluded that using the data would not enlighten the discussion about insulin use and cancer risk and only serve to further complicate any understanding. Therefore, we decided to use our experience to illustrate methodological challenges...

  9. A game-theoretic approach to optimize ad hoc networks inspired by small-world network topology

    Science.gov (United States)

    Tan, Mian; Yang, Tinghong; Chen, Xing; Yang, Gang; Zhu, Guoqing; Holme, Petter; Zhao, Jing

    2018-03-01

    Nodes in ad hoc networks are connected in a self-organized manner. Limited communication radius makes information transmit in multi-hop mode, and each forwarding needs to consume the energy of nodes. Insufficient communication radius or exhaustion of energy may cause the absence of some relay nodes and links, further breaking network connectivity. On the other hand, nodes in the network may refuse to cooperate due to objective faulty or personal selfish, hindering regular communication in the network. This paper proposes a model called Repeated Game in Small World Networks (RGSWN). In this model, we first construct ad hoc networks with small-world feature by forming "communication shortcuts" between multiple-radio nodes. Small characteristic path length reduces average forwarding times in networks; meanwhile high clustering coefficient enhances network robustness. Such networks still maintain relative low global power consumption, which is beneficial to extend the network survival time. Then we use MTTFT strategy (Mend-Tolerance Tit-for-Tat) for repeated game as a rule for the interactions between neighbors in the small-world networks. Compared with other five strategies of repeated game, this strategy not only punishes the nodes' selfishness more reasonably, but also has the best tolerance to the network failure. This work is insightful for designing an efficient and robust ad hoc network.

  10. Accurate 3D Localization Method for Public Safety Applications in Vehicular Ad-hoc Networks

    KAUST Repository

    Ansari, Abdul Rahim; Saeed, Nasir; Haq, Mian Imtiaz Ul; Cho, Sunghyun

    2018-01-01

    Vehicular ad hoc networks (VANETs) represent a very promising research area because of their ever increasing demand, especially for public safety applications. In VANETs vehicles communicate with each other to exchange road maps and traffic

  11. DRAM fault analysis and test generation

    NARCIS (Netherlands)

    Al-Ars, Z.

    2005-01-01

    Dynamic random access memories (DRAMs) are the most widely used type of memory in the market today, due to their important application as the main memory of the personal computer (PC). These memories are tested by their manufacturers in an ad hoc way, that results in an expensive test process the

  12. A framework for reactive optimization in mobile ad hoc networks

    DEFF Research Database (Denmark)

    McClary, Dan; Syrotiuk, Violet; Kulahci, Murat

    2008-01-01

    We present a framework to optimize the performance of a mobile ad hoc network over a wide range of operating conditions. It includes screening experiments to quantify the parameters and interactions among parameters influential to throughput. Profile-driven regression is applied to obtain a model....... The predictive accuracy of the model is monitored and used to update the model dynamically. The results indicate the framework may be useful for the optimization of dynamic systems of high dimension....

  13. Dynamic fair node spectrum allocation for ad hoc networks using random matrices

    Science.gov (United States)

    Rahmes, Mark; Lemieux, George; Chester, Dave; Sonnenberg, Jerry

    2015-05-01

    Dynamic Spectrum Access (DSA) is widely seen as a solution to the problem of limited spectrum, because of its ability to adapt the operating frequency of a radio. Mobile Ad Hoc Networks (MANETs) can extend high-capacity mobile communications over large areas where fixed and tethered-mobile systems are not available. In one use case with high potential impact, cognitive radio employs spectrum sensing to facilitate the identification of allocated frequencies not currently accessed by their primary users. Primary users own the rights to radiate at a specific frequency and geographic location, while secondary users opportunistically attempt to radiate at a specific frequency when the primary user is not using it. We populate a spatial radio environment map (REM) database with known information that can be leveraged in an ad hoc network to facilitate fair path use of the DSA-discovered links. Utilization of high-resolution geospatial data layers in RF propagation analysis is directly applicable. Random matrix theory (RMT) is useful in simulating network layer usage in nodes by a Wishart adjacency matrix. We use the Dijkstra algorithm for discovering ad hoc network node connection patterns. We present a method for analysts to dynamically allocate node-node path and link resources using fair division. User allocation of limited resources as a function of time must be dynamic and based on system fairness policies. The context of fair means that first available request for an asset is not envied as long as it is not yet allocated or tasked in order to prevent cycling of the system. This solution may also save money by offering a Pareto efficient repeatable process. We use a water fill queue algorithm to include Shapley value marginal contributions for allocation.

  14. Performance analysis of differentiated resource-sharing in a wireless ad-hoc network

    NARCIS (Netherlands)

    Roijers, F.; van den Berg, H.; Mandjes, M.

    2010-01-01

    In this paper we model and analyze a relay node in a wireless ad-hoc network; the capacity available at this node is used to both transmit traffic from the source nodes (towards the relay node), and to serve traffic at the relay node (so that it can be forwarded to successor nodes). Clearly, a

  15. A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks.

    Science.gov (United States)

    Chen, Huifang; Ge, Linlin; Xie, Lei

    2015-07-14

    The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes.

  16. Report of the independent Ad Hoc Group for the Davis-Besse incident

    International Nuclear Information System (INIS)

    1986-06-01

    The Nuclear Regulatory Commission established an independent Ad Hoc Group in January 1986 to review issues subsequent to a complete loss of feedwater event at Davis-Besse Nuclear Power Station on June 9, 1985, including the NRC Incident Investigation Team (IIT) investigation of that event. The Commission asked the Group to identify additional lessons that might be learned and from these to make recommendations to improve NRC oversight of reactor licensees. To fulfill its charter, the Ad Hoc Group examined the following: (1) pre-event interactions between the licensee and NRC concerning reliability of the auxiliary feedwater system and associated systems; (2) pre-event probabilistic assessments of the reliability of plant safety systems, NRC's review of them, and their use in regulatory decisionmaking; (3) licensee management, operation and maintenance programs as they may have contributed to equipment failures and NRC oversight of such programs; and (4) the mandate, capabilities of members, operation, and results of the NRC Davis-Besse IIT, and the use to which its report was put by the regulatory staff

  17. Content Downloading with the Assistance of Roadside Cars for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Haigang Gong

    2017-01-01

    Full Text Available Plenty of multimedia contents such as traffic images, music, and movies pose great challenges for content downloading due to the high mobility of vehicles and intermittent connectivity for vehicular ad hoc networks. Roadside units or APs can improve the efficiency of content downloading but with the cost of large investments. In this paper, an efficient content downloading scheme is proposed with the assistance of parking clusters, which are formed by roadside parked cars. After receiving the downloading request, the parking clusters, which the downloader will travel through according to the estimated trajectory, will make a download scheduling for the downloader. Then the downloader acquires the content chunks while it drives through the parking clusters. Simulation results show that the proposed scheme achieves better performance than intervehicle approach and RSU based approach.

  18. Ad Hoc Transient Communities to Enhance Social Interaction and Spread Tutor Responsibilities

    OpenAIRE

    Sloep, Peter; Kester, Liesbeth; Brouns, Francis; Van Rosmalen, Peter; De Vries, Fred; De Croock, Marcel; Koper, Rob

    2007-01-01

    Sloep, P.B., Kester, L. Brouns, F., Van Rosmalen, P., De Vries, F., De Croock, M., Koper, R. (2007) Ad Hoc Transient Communities to Enhance Social Interaction and Spread Tutor Responsibilities. In V. Uskov (Ed.) The Sixth IASTED International Conference on Web-based Education WBE 2007, March 14-16, Chamonix, France (pp. 549-554). Calgary, Canada: Acta Press.

  19. Forming an ad-hoc nearby storage, based on IKAROS and social networking services

    International Nuclear Information System (INIS)

    Filippidis, Christos; Cotronis, Yiannis; Markou, Christos

    2014-01-01

    We present an ad-hoc 'nearby' storage, based on IKAROS and social networking services, such as Facebook. By design, IKAROS is capable to increase or decrease the number of nodes of the I/O system instance on the fly, without bringing everything down or losing data. IKAROS is capable to decide the file partition distribution schema, by taking on account requests from the user or an application, as well as a domain or a Virtual Organization policy. In this way, it is possible to form multiple instances of smaller capacity higher bandwidth storage utilities capable to respond in an ad-hoc manner. This approach, focusing on flexibility, can scale both up and down and so can provide more cost effective infrastructures for both large scale and smaller size systems. A set of experiments is performed comparing IKAROS with PVFS2 by using multiple clients requests under HPC IOR benchmark and MPICH2.

  20. Forming an ad-hoc nearby storage, based on IKAROS and social networking services

    Science.gov (United States)

    Filippidis, Christos; Cotronis, Yiannis; Markou, Christos

    2014-06-01

    We present an ad-hoc "nearby" storage, based on IKAROS and social networking services, such as Facebook. By design, IKAROS is capable to increase or decrease the number of nodes of the I/O system instance on the fly, without bringing everything down or losing data. IKAROS is capable to decide the file partition distribution schema, by taking on account requests from the user or an application, as well as a domain or a Virtual Organization policy. In this way, it is possible to form multiple instances of smaller capacity higher bandwidth storage utilities capable to respond in an ad-hoc manner. This approach, focusing on flexibility, can scale both up and down and so can provide more cost effective infrastructures for both large scale and smaller size systems. A set of experiments is performed comparing IKAROS with PVFS2 by using multiple clients requests under HPC IOR benchmark and MPICH2.

  1. The effect of DAD timeout period on address autoconfiguration in wireless ad-hoc networks

    CSIR Research Space (South Africa)

    Mutanga, MB

    2011-09-01

    Full Text Available Lack of manual management mechanisms in wireless ad-hoc networks means that automatic configuration of IP addresses and other related network parameters are very crucial. Many IP address autoconfiguration mechanisms have been proposed in literature...

  2. An Economic Framework for Resource Allocation in Ad-hoc Grids

    OpenAIRE

    Pourebrahimi, B.

    2009-01-01

    In this dissertation, we present an economic framework to study and develop different market-based mechanisms for resource allocation in an ad-hoc Grid. Such an economic framework helps to understand the impact of certain choices and explores what are the suitable mechanisms from Grid user/owner perspectives under given circumstances. We focus on resource allocation in a Grid-based environment in the case where some resources are lying idle and could be linked with overloaded nodes in a netwo...

  3. Report of the evaluation by the ad hoc review committee on advanced photon and synchrotron radiation research. In-advance evaluation in fiscal year 2001

    International Nuclear Information System (INIS)

    2001-11-01

    The Research Evaluation Committee, which consisted of 13 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Advanced Photon and Synchrotron Radiation Research in accordance with the 'Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the adequacy of the R and D programs to be implemented for five years starting in Fiscal Year 2002 at Advanced Photon Research Center and at Synchrotron Radiation Research Center in Kansai Research Establishment of JAERI. The Ad Hoc Review Committee consisted of ten specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from May to July 2001. The evaluation was performed on the basis of the materials submitted in advanced and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on June 21, 2001, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on July 12, 2001. This report describes the result of the evaluation by the Ad Hoc Review Committee on Advanced Photon and Synchrotron Radiation Research. (author)

  4. Clustering of Mobile Ad Hoc Networks: An Adaptive Broadcast Period Approach

    OpenAIRE

    Gavalas, Damianos; Pantziou, Grammati; Konstantopoulos, Charalampos; Mamalis, Basilis

    2011-01-01

    Organization, scalability and routing have been identified as key problems hindering viability and commercial success of mobile ad hoc networks. Clustering of mobile nodes among separate domains has been proposed as an efficient approach to address those issues. In this work, we introduce an efficient distributed clustering algorithm that uses both location and energy metrics for cluster formation. Our proposed solution mainly addresses cluster stability, manageability and energy efficiency i...

  5. Reducing Congestion in Obstructed Highways with Traffic Data Dissemination Using Ad hoc Vehicular Networks

    Directory of Open Access Journals (Sweden)

    Coveney PeterV

    2010-01-01

    Full Text Available Vehicle-to-vehicle communications can be used effectively for intelligent transport systems (ITSs and location-aware services. The ability to disseminate information in an ad hoc fashion allows pertinent information to propagate faster through a network. In the realm of ITS, the ability to spread warning information faster and further is of great advantage to receivers. In this paper we propose and present a message-dissemination procedure that uses vehicular wireless protocols to influence vehicular flow, reducing congestion in road networks. The computational experiments we present show how a car-following model and lane-change algorithm can be adapted to "react" to the reception of information. This model also illustrates the advantages of coupling together with vehicular flow modelling tools and network simulation tools.

  6. A Performance Evaluation Model for Mobile Ad Hoc Networks and Sensor Networks

    Directory of Open Access Journals (Sweden)

    Heng LUO

    2014-03-01

    Full Text Available Potential applications in areas such as military sites and disaster relief fields that are characterized by absence of prefixed infrastructure justify the development of mobile ad hoc networks (MANETs and wireless sensor networks (WSNs. However, unfavorable wireless links and dynamic topology are still challenging, leading to the proposal of a collection of routing protocols for MANETs and WSNs. Nevertheless the performance of algorithms may vary with deployment scenario due to the application dependent philosophy behind algorithms. In this paper, the performance evaluation problem for MANETs and WSNs is investigated and a novel performance ranking model, termed AHP-SAW, is proposed. For simplicity but without loss of generality, the performance of two routing protocols DSDV and DSR are studies based on which ranking results are provided. Extensive simulations show that an overall 37.2 %, at most, gain may be achieved based on the AHP-SAW model.

  7. Assessing Clinical Microbiology Practice Guidelines: American Society for Microbiology Ad Hoc Committee on Evidence-Based Laboratory Medicine Practice Guidelines Assessment.

    Science.gov (United States)

    Nachamkin, Irving; Kirn, Thomas J; Westblade, Lars F; Humphries, Romney

    2017-11-01

    As part of the American Society for Microbiology (ASM) Evidence-Based Laboratory Medicine Practice Guidelines Committee of the Professional Practice Committee, an ad hoc committee was formed in 2014 to assess guidelines published by the committee using an assessment tool, Appraisal of Guidelines for Research Evaluation II (AGREE II). The AGREE II assessment helps reviewers determine whether published guidelines are robust, transparent, and clear in presenting practice recommendations in a standardized manner. Identifying strengths and weaknesses of practice guidelines by ad hoc assessments helps with improving future guidelines through the participation of key stakeholders. This minireview describes the development of the ad hoc committee and results from their review of several ASM best practices guidelines and a non-ASM practice guideline from the Emergency Nurses Association. Copyright © 2017 American Society for Microbiology.

  8. Two-terminal reliability analyses for a mobile ad hoc wireless network

    International Nuclear Information System (INIS)

    Cook, Jason L.; Ramirez-Marquez, Jose Emmanuel

    2007-01-01

    Reliability is one of the most important performance measures for emerging technologies. For these systems, shortcomings are often overlooked in early releases as the cutting edge technology overshadows a fragile design. Currently, the proliferation of the mobile ad hoc wireless networks (MAWN) is moving from cutting edge to commodity and thus, reliable performance will be expected. Generally, ad hoc networking is applied for the flexibility and mobility it provides. As a result, military and first responders employ this network scheme and the reliability of the network becomes paramount. To ensure reliability is achieved, one must first be able to analyze and calculate the reliability of the MAWN. This work describes the unique attributes of the MAWN and how the classical analysis of network reliability, where the network configuration is known a priori, can be adjusted to model and analyze this type of network. The methods developed acknowledge the dynamic and scalable nature of the MAWN along with its absence of infrastructure. Thus, the methods rely on a modeling approach that considers the probabilistic formation of different network configurations in a MAWN. Hence, this paper proposes reliability analysis methods that consider the effect of node mobility and the continuous changes in the network's connectivity

  9. Neuromathematical Trichotomous Mixed Methods Analysis: Using the Neuroscientific Tri-Squared Test Statistical Metric as a Post Hoc Analytic to Determine North Carolina School of Science and Mathematics Leadership Efficacy

    Science.gov (United States)

    Osler, James Edward, II; Mason, Letita R.

    2016-01-01

    This study examines the leadership efficacy amongst graduates of The North Carolina School of Science and Mathematics (NCSSM) for the classes of 2000 through 2007 from a neuroscientific and neuromathematic perspective. NCSSM alumni (as the primary unit of analysis) were examined using a novel neuromathematic post hoc method of analysis. This study…

  10. On Energy-Efficient Hierarchical Cross-Layer Design: Joint Power Control and Routing for Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Poor HVincent

    2007-01-01

    Full Text Available A hierarchical cross-layer design approach is proposed to increase energy efficiency in ad hoc networks through joint adaptation of nodes' transmitting powers and route selection. The design maintains the advantages of the classic OSI model, while accounting for the cross-coupling between layers, through information sharing. The proposed joint power control and routing algorithm is shown to increase significantly the overall energy efficiency of the network, at the expense of a moderate increase in complexity. Performance enhancement of the joint design using multiuser detection is also investigated, and it is shown that the use of multiuser detection can increase the capacity of the ad hoc network significantly for a given level of energy consumption.

  11. On Energy-Efficient Hierarchical Cross-Layer Design: Joint Power Control and Routing for Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Cristina Comaniciu

    2007-03-01

    Full Text Available A hierarchical cross-layer design approach is proposed to increase energy efficiency in ad hoc networks through joint adaptation of nodes' transmitting powers and route selection. The design maintains the advantages of the classic OSI model, while accounting for the cross-coupling between layers, through information sharing. The proposed joint power control and routing algorithm is shown to increase significantly the overall energy efficiency of the network, at the expense of a moderate increase in complexity. Performance enhancement of the joint design using multiuser detection is also investigated, and it is shown that the use of multiuser detection can increase the capacity of the ad hoc network significantly for a given level of energy consumption.

  12. Wireless ad hoc and sensor networks management, performance, and applications

    CERN Document Server

    He, Jing

    2013-01-01

    Although wireless sensor networks (WSNs) have been employed across a wide range of applications, there are very few books that emphasize the algorithm description, performance analysis, and applications of network management techniques in WSNs. Filling this need, Wireless Ad Hoc and Sensor Networks: Management, Performance, and Applications summarizes not only traditional and classical network management techniques, but also state-of-the-art techniques in this area. The articles presented are expository, but scholarly in nature, including the appropriate history background, a review of current

  13. An ad hoc wireless sensor network for tele medicine applications

    International Nuclear Information System (INIS)

    Sheltami, Tarek R.; Mahmoud, Ashraf S.; Abu-Amara, Marwan H.

    2007-01-01

    Recent advances in embedded computing systems have led to the emergence of wireless sensor networks (SNETs), consisting of small, battery-powered motes with limited computation and radio communication capabilities. SNETs permit data gathering and computation to be deeply embedded in the physical environment. Large scale ad hoc sensor networks (ASNET), when deployed among mobile patients, can provide dynamic data query architecture to allow medical specialists to monitor patients at any place via the web or cellular network. In case of an emergency, doctors and/or nurses will be contacted automatically through their handheld personal digital assistants (PDAs) or cellular phones. In specific, the proposed network consists of sensor nodes at the first layer whose responsibility is to measure, collect and communicate, via wired or wireless interface, readings to a microcontroller presenting the second layer of architecture. Deployed microcontrollers process incoming readings and report to a central system via a wireless interface. The implemented network distinguishes between periodic sensor readings and critical or event driven readings where higher priorities is given for the latter. In this paper we implement 3 special cases for tracking and monitoring patients and doctors using SNETs. In addition, the performance of a large scale of our implementation has been tested by means of mathematical analysis. (author)

  14. PUCA: A Pseudonym Scheme with User-Controlled Anonymity for Vehicular Ad-Hoc Networks (VANET)

    NARCIS (Netherlands)

    Förster, David; Kargl, Frank; Löhr, Hans

    2014-01-01

    Envisioned vehicular ad-hoc networks (VANET) standards use pseudonym certificates to provide secure and privacy-friendly message authentication. Revocation of long-term credentials is required to remove participants from the system, e.g. in case of vehicle theft. However, the current approach to

  15. Securing mobile ad hoc networks using danger theory-based artificial immune algorithm.

    Science.gov (United States)

    Abdelhaq, Maha; Alsaqour, Raed; Abdelhaq, Shawkat

    2015-01-01

    A mobile ad hoc network (MANET) is a set of mobile, decentralized, and self-organizing nodes that are used in special cases, such as in the military. MANET properties render the environment of this network vulnerable to different types of attacks, including black hole, wormhole and flooding-based attacks. Flooding-based attacks are one of the most dangerous attacks that aim to consume all network resources and thus paralyze the functionality of the whole network. Therefore, the objective of this paper is to investigate the capability of a danger theory-based artificial immune algorithm called the mobile dendritic cell algorithm (MDCA) to detect flooding-based attacks in MANETs. The MDCA applies the dendritic cell algorithm (DCA) to secure the MANET with additional improvements. The MDCA is tested and validated using Qualnet v7.1 simulation tool. This work also introduces a new simulation module for a flooding attack called the resource consumption attack (RCA) using Qualnet v7.1. The results highlight the high efficiency of the MDCA in detecting RCAs in MANETs.

  16. Report of the evaluation by the Ad Hoc Review Committee on advance science research. Result evaluation, interim evaluation, in-advance evaluation in fiscal year 2003

    International Nuclear Information System (INIS)

    2003-11-01

    The Research Evaluation Committee, which consisted of 13 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Advanced Science Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the accomplishments of the research completed in Fiscal Year 2002, the accomplishments of the research started in Fiscal Year 2001, and the adequacy of the programs of the research to be started in Fiscal Year 2004 at Advanced Science Research Center of JAERI. The Ad Hoc Review Committee consisted of nine specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from May to July 2003. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on June 24, 2003, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on August 4, 2003. This report describes the result of the evaluation by the Ad Hoc Review Committee on Advanced Science Research. (author)

  17. Report of the evaluation by the Ad Hoc Review Committee on Advance Science Research. Result evaluation, interim evaluation, in-advance evaluation in fiscal year 2002

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-11-01

    The Research Evaluation Committee, which consisted of 13 members from outside of the Japan Atomic Energy Research Institute (JAERI), set up an Ad Hoc Review Committee on Advanced Science Research in accordance with the Fundamental Guideline for the Evaluation of Research and Development (R and D) at JAERI' and its subsidiary regulations in order to evaluate the accomplishments of the research completed in Fiscal Year 2001, the accomplishments of the research started in Fiscal Year 2000, and the adequacy of the programs of the research to be started in Fiscal Year 2003 at Advanced Science Research Center of JAERI. The Ad Hoc Review Committee consisted of eight specialists from outside of JAERI. The Ad Hoc Review Committee conducted its activities from May to July 2002. The evaluation was performed on the basis of the materials submitted in advance and of the oral presentations made at the Ad Hoc Review Committee meeting which was held on June 4, 2002, in line with the items, viewpoints, and criteria for the evaluation specified by the Research Evaluation Committee. The result of the evaluation by the Ad Hoc Review Committee was submitted to the Research Evaluation Committee, and was judged to be appropriate at its meeting held on August 5, 2002. This report describes the result of the evaluation by the Ad Hoc Review Committee on Advanced Science Research. (author)

  18. Construction of Pipelined Strategic Connected Dominating Set for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Ceronmani Sharmila

    2016-06-01

    Full Text Available Efficient routing between nodes is the most important challenge in a Mobile Ad Hoc Network (MANET. A Connected Dominating Set (CDS acts as a virtual backbone for routing in a MANET. Hence, the construction of CDS based on the need and its application plays a vital role in the applications of MANET. The PipeLined Strategic CDS (PLS-CDS is constructed based on strategy, dynamic diameter and transmission range. The strategy used for selecting the starting node is, any source node in the network, which has its entire destination within a virtual pipelined coverage, instead of the node with maximum connectivity. The other nodes are then selected based on density and velocity. The proposed CDS also utilizes the energy of the nodes in the network in an optimized manner. Simulation results showed that the proposed algorithm is better in terms of size of the CDS and average hop per path length.

  19. Performance Analysis of Routing Protocols in Ad-hoc and Sensor Networking Environments

    Directory of Open Access Journals (Sweden)

    L. Gavrilovska

    2009-06-01

    Full Text Available Ad-hoc and sensor networks are becoming an increasingly popular wireless networking concepts lately. This paper analyzes and compares prominent routing schemes in these networking environments. The knowledge obtained can serve users to better understand short range wireless network solutions thus leading to options for implementation in various scenarios. In addition, it should aid researchers develop protocol improvements reliable for the technologies of interest.

  20. A Dynamic Reputation Management System for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Eric Chiejina

    2015-04-01

    Full Text Available Nodes in mobile ad hoc networks (MANETs are mandated to utilize their limited energy resources in forwarding routing control and data packets for other nodes. Since a MANET lacks a centralized administration and control, a node may decide to act selfishly, either by refusing to respond to route requests from other nodes or deceitfully by responding to some route requests, but dropping the corresponding data packets that are presented for forwarding. A significant increase in the presence of these misbehaving nodes in a MANET can subsequently degrade network performance. In this paper, we propose a dynamic reputation management system for detecting and isolating misbehaving nodes in MANETs. Our model employs a novel direct monitoring technique to evaluate the reputation of a node in the network, which ensures that nodes that expend their energy in transmitting data and routing control packets for others are allowed to carry out their network activities while the misbehaving nodes are detected and isolated from the network. Simulation results show that our model is effective at curbing and mitigating the effects of misbehaving nodes in the network.

  1. Cross-Layer QoS Control for Video Communications over Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Pei Yong

    2005-01-01

    Full Text Available Assuming a wireless ad hoc network consisting of homogeneous video users with each of them also serving as a possible relay node for other users, we propose a cross-layer rate-control scheme based on an analytical study of how the effective video transmission rate is affected by the prevailing operating parameters, such as the interference environment, the number of transmission hops to a destination, and the packet loss rate. Furthermore, in order to provide error-resilient video delivery over such wireless ad hoc networks, a cross-layer joint source-channel coding (JSCC approach, to be used in conjunction with rate-control, is proposed and investigated. This approach attempts to optimally apply the appropriate channel coding rate given the constraints imposed by the effective transmission rate obtained from the proposed rate-control scheme, the allowable real-time video play-out delay, and the prevailing channel conditions. Simulation results are provided which demonstrate the effectiveness of the proposed cross-layer combined rate-control and JSCC approach.

  2. A Novel Medium Access Control for Ad hoc Networks Based on OFDM System

    Institute of Scientific and Technical Information of China (English)

    YU Yi-fan; YIN Chang-chuan; YUE Guang-xin

    2005-01-01

    Recently, hosts of Medium Access Control (MAC) protocols for Ad hoc radio networks have been proposed to solve the hidden terminal problem and exposed terminal problem. However most of them take into no account the interactions between physical (PHY) system and MAC protocol. Therefore, the current MAC protocols are either inefficient in the networks with mobile nodes and fading channel or difficult in hardware implementation. In this paper, we present a novel media access control for Ad hoc networks that integrates a media access control protocol termed as Dual Busy Tone Multiple Access (DBTMA) into Orthogonal Frequency Division Multiplexing (OFDM) system proposed in IEEE 802.11a standard. The analysis presented in the paper indicates that the proposed MAC scheme achieves performance improvement over IEEE 802.11 protocol about 25%~80% especially in the environment with high mobility and deep fading. The complexity of the proposed scheme is also lower than other implementation of similar busy tone solution. Furthermore, it is compatible with IEEE 802.11a networks.

  3. A Unified NET-MAC-PHY Cross-layer Framework for Performance Evaluation of Multi-hop Ad hoc WLANs

    Directory of Open Access Journals (Sweden)

    Rachid El-Azouzi

    2014-09-01

    Full Text Available Most of the existing works have been evaluated the performance of 802.11 multihop networks by considering the MAC layer or network layer separately. Knowing the nature of the multi-hop ad hoc networks, many factors in different layers are crucial for study the performance of MANET. In this paper we present a new analytic model for evaluating average end-to-end throughput in IEEE 802.11e multihop wireless networks. In particular, we investigate an intricate interaction among PHY, MAC and Network layers. For instance, we incorporate carrier sense threshold, transmission power, contention window size, retransmissions retry limit, multi rates, routing protocols and network topology together. We build a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and asymmetric traffic. We develop an analytical model to predict throughput of each connection as well as stability of forwarding queues at intermediate nodes in saturated networks. To the best of our knowledge, it seems that our work is the first wherein general topology and asymmetric parameters setup are considered in PHY/MAC/Network layers. Performance of such a system is also evaluated through simulation. We show that performance measures of the MAC layer are affected by the traffic intensity of flows to be forwarded. More precisely, attempt rate and collision probability are dependent on traffic flows, topology and routing.

  4. Minimizing Detection Probability Routing in Ad Hoc Networks Using Directional Antennas

    Directory of Open Access Journals (Sweden)

    Towsley Don

    2009-01-01

    Full Text Available In a hostile environment, it is important for a transmitter to make its wireless transmission invisible to adversaries because an adversary can detect the transmitter if the received power at its antennas is strong enough. This paper defines a detection probability model to compute the level of a transmitter being detected by a detection system at arbitrary location around the transmitter. Our study proves that the probability of detecting a directional antenna is much lower than that of detecting an omnidirectional antenna if both the directional and omnidirectional antennas provide the same Effective Isotropic Radiated Power (EIRP in the direction of the receiver. We propose a Minimizing Detection Probability (MinDP routing algorithm to find a secure routing path in ad hoc networks where nodes employ directional antennas to transmit data to decrease the probability of being detected by adversaries. Our study shows that the MinDP routing algorithm can reduce the total detection probability of deliveries from the source to the destination by over 74%.

  5. Cooperative Caching in Mobile Ad Hoc Networks Based on Data Utility

    Directory of Open Access Journals (Sweden)

    Narottam Chand

    2007-01-01

    Full Text Available Cooperative caching, which allows sharing and coordination of cached data among clients, is a potential technique to improve the data access performance and availability in mobile ad hoc networks. However, variable data sizes, frequent data updates, limited client resources, insufficient wireless bandwidth and client's mobility make cache management a challenge. In this paper, we propose a utility based cache replacement policy, least utility value (LUV, to improve the data availability and reduce the local cache miss ratio. LUV considers several factors that affect cache performance, namely access probability, distance between the requester and data source/cache, coherency and data size. A cooperative cache management strategy, Zone Cooperative (ZC, is developed that employs LUV as replacement policy. In ZC one-hop neighbors of a client form a cooperation zone since the cost for communication with them is low both in terms of energy consumption and message exchange. Simulation experiments have been conducted to evaluate the performance of LUV based ZC caching strategy. The simulation results show that, LUV replacement policy substantially outperforms the LRU policy.

  6. Integrated data lookup and replication scheme in mobile ad hoc networks

    Science.gov (United States)

    Chen, Kai; Nahrstedt, Klara

    2001-11-01

    Accessing remote data is a challenging task in mobile ad hoc networks. Two problems have to be solved: (1) how to learn about available data in the network; and (2) how to access desired data even when the original copy of the data is unreachable. In this paper, we develop an integrated data lookup and replication scheme to solve these problems. In our scheme, a group of mobile nodes collectively host a set of data to improve data accessibility for all members of the group. They exchange data availability information by broadcasting advertising (ad) messages to the group using an adaptive sending rate policy. The ad messages are used by other nodes to derive a local data lookup table, and to reduce data redundancy within a connected group. Our data replication scheme predicts group partitioning based on each node's current location and movement patterns, and replicates data to other partitions before partitioning occurs. Our simulations show that data availability information can quickly propagate throughout the network, and that the successful data access ratio of each node is significantly improved.

  7. Topology Control with Anisotropic and Sector Turning Antennas in Ad-hoc and Sensor Networks

    Directory of Open Access Journals (Sweden)

    V. Černý

    2011-01-01

    Full Text Available During the last several years, technological advances have allowed the development of small, cheap, embedded, independent and rather powerful radio devices that can self-organise into data networks. Such networks are usually called ad-hoc networks or, sometimes, depending on the application field, sensor networks. One of the first standards for ad-hoc networks to impose itself as a fully industrial framework for data gathering and control over such devices is IEEE 802.15.4 and, on top of it, its pair network architecture: ZigBee. In the case of multiple radio devices clamped into a small geographical area, the lack of radio bandwidth becomes a major problem, leading to multiple data losses and unnecessary power drain from the batteries of these small devices. This problem is usually perceived as interference. The deployment of appropriate topology control mechanisms (TC can solve interference. All of these algorithms calculate TC on the basis of isotropic antenna radiation patterns in the horizontal plane.

  8. Client-Server and Peer-to-Peer Ad-hoc Network for a Flexible Learning Environment

    Directory of Open Access Journals (Sweden)

    Ferial Khaddage

    2011-01-01

    Full Text Available Peer-to-Peer (P2P networking in a mobile learning environment has become a popular topic of research. One of the new emerging research ideas is on the ability to combine P2P network with server-based network to form a strong efficient portable and compatible network infrastructure. This paper describes a unique mobile network architecture, which reflects the on-campus students’ need for a mobile learning environment. This can be achieved by combining two different networks, client-server and peer-to-peer ad-hoc to form a sold and secure network. This is accomplished by employing one peer within the ad-hoc network to act as an agent-peer to facilitate communication and information sharing between the two networks. It can be implemented without any major changes to the current network technologies, and can combine any wireless protocols such as GPRS, Wi-Fi, Bluetooth, and 3G.

  9. Adhoc: an R package to calculate ad hoc distance thresholds for DNA barcoding identification

    Directory of Open Access Journals (Sweden)

    Gontran Sonet

    2013-12-01

    Full Text Available Identification by DNA barcoding is more likely to be erroneous when it is based on a large distance between the query (the barcode sequence of the specimen to identify and its best match in a reference barcode library. The number of such false positive identifications can be decreased by setting a distance threshold above which identification has to be rejected. To this end, we proposed recently to use an ad hoc distance threshold producing identifications with an estimated relative error probability that can be fixed by the user (e.g. 5%. Here we introduce two R functions that automate the calculation of ad hoc distance thresholds for reference libraries of DNA barcodes. The scripts of both functions, a user manual and an example file are available on the JEMU website (http://jemu.myspecies.info/computer-programs as well as on the comprehensive R archive network (CRAN, http://cran.r-project.org.

  10. A Family of ACO Routing Protocols for Mobile Ad Hoc Networks

    Science.gov (United States)

    Rupérez Cañas, Delfín; Sandoval Orozco, Ana Lucila; García Villalba, Luis Javier; Kim, Tai-hoon

    2017-01-01

    In this work, an ACO routing protocol for mobile ad hoc networks based on AntHocNet is specified. As its predecessor, this new protocol, called AntOR, is hybrid in the sense that it contains elements from both reactive and proactive routing. Specifically, it combines a reactive route setup process with a proactive route maintenance and improvement process. Key aspects of the AntOR protocol are the disjoint-link and disjoint-node routes, separation between the regular pheromone and the virtual pheromone in the diffusion process and the exploration of routes, taking into consideration the number of hops in the best routes. In this work, a family of ACO routing protocols based on AntOR is also specified. These protocols are based on protocol successive refinements. In this work, we also present a parallelized version of AntOR that we call PAntOR. Using programming multiprocessor architectures based on the shared memory protocol, PAntOR allows running tasks in parallel using threads. This parallelization is applicable in the route setup phase, route local repair process and link failure notification. In addition, a variant of PAntOR that consists of having more than one interface, which we call PAntOR-MI (PAntOR-Multiple Interface), is specified. This approach parallelizes the sending of broadcast messages by interface through threads. PMID:28531159

  11. A Family of ACO Routing Protocols for Mobile Ad Hoc Networks.

    Science.gov (United States)

    Rupérez Cañas, Delfín; Sandoval Orozco, Ana Lucila; García Villalba, Luis Javier; Kim, Tai-Hoon

    2017-05-22

    In this work, an ACO routing protocol for mobile ad hoc networks based on AntHocNet is specified. As its predecessor, this new protocol, called AntOR, is hybrid in the sense that it contains elements from both reactive and proactive routing. Specifically, it combines a reactive route setup process with a proactive route maintenance and improvement process. Key aspects of the AntOR protocol are the disjoint-link and disjoint-node routes, separation between the regular pheromone and the virtual pheromone in the diffusion process and the exploration of routes, taking into consideration the number of hops in the best routes. In this work, a family of ACO routing protocols based on AntOR is also specified. These protocols are based on protocol successive refinements. In this work, we also present a parallelized version of AntOR that we call PAntOR. Using programming multiprocessor architectures based on the shared memory protocol, PAntOR allows running tasks in parallel using threads. This parallelization is applicable in the route setup phase, route local repair process and link failure notification. In addition, a variant of PAntOR that consists of having more than one interface, which we call PAntOR-MI (PAntOR-Multiple Interface), is specified. This approach parallelizes the sending of broadcast messages by interface through threads.

  12. 移动Ad Hoc网络路由协议综述%A Survey of Routing Protocols for Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    张顺亮; 叶澄清; 李方敏

    2003-01-01

    A review of current research about routing protocols for mobile Ad Hoc networks is made. Based on classifying of them, the characteristic, the strength and the weakness of these protocols are evaluated respectively. Then some crucial strategies to improve the existing routing protocols are proposed. Besides, a frame of new routing protocol for Ad Hoc networks is put forward. Finally, open issues that still need investigation are listed.

  13. An Automated Tool for the Creation of Desired Emulated Topologies of a Mobile Ad-Hoc Network

    National Research Council Canada - National Science Library

    Nguyen, Binh Q

    2006-01-01

    This report documents a research effort that the U.S. Army Research Laboratory conducted in FY 2005 in support of the development of advanced technologies for tactical mobile ad hoc networks (MANET...

  14. Assessment of direct analgesic effect of duloxetine for chronic low back pain: post hoc path analysis of double-blind, placebo-controlled studies

    Directory of Open Access Journals (Sweden)

    Enomoto H

    2017-06-01

    Full Text Available Hiroyuki Enomoto,1 Shinji Fujikoshi,2 Jumpei Funai,3 Nao Sasaki,4 Michael H Ossipov,5 Toshinaga Tsuji,6 Levent Alev,7 Takahiro Ushida8 1Medical Science, Eli Lilly Japan K.K., Tokyo, 2Statistical Science, 3Science Communications, 4Medical Science, Eli Lilly Japan K.K., Kobe, Japan; 5Clinical Division, inVentiv Health, LLC, Blue Bell, PA, USA; 6Medical Affairs Department, Shionogi & Co., Ltd., Osaka, Japan; 7Medical Department, Lilly Turkey, Istanbul, Turkey; 8Multidisciplinary Pain Center, Aichi Medical University, Nagakute, Aichi, Japan Background: Comorbid depression and depressive symptoms are common in patients with chronic low back pain (CLBP. Duloxetine is clinically effective in major depressive disorder and several chronic pain states, including CLBP. The objective of this post hoc meta-analysis was to assess direct and indirect analgesic efficacy of duloxetine for patients with CLBP in previous clinical trials. Methods: Post hoc path analyses were conducted of 3 randomized, double-blind, clinical studies of patients receiving duloxetine or placebo for CLBP. The primary outcome measure for pain was the Brief Pain Inventory, average pain score. A secondary outcome measure, the Beck Depression Inventory-II, was used for depressive symptoms. The changes in score from baseline to endpoint were determined for each index. Path analyses were employed to calculate the proportion of analgesia that may be attributed to a direct effect of duloxetine on pain.Results: A total of 851 patients (400 duloxetine and 451 placebo were included in this analysis. Duloxetine significantly improved pain scores compared with placebo (p<0.001. It also significantly improved depressive scores compared with placebo (p=0.015. Path analyses showed that 91.1% of the analgesic effect of duloxetine could be attributed to a direct analgesic effect, and 8.9% to its antidepressant effect. Similar results were obtained when data were evaluated at weeks 4 and 7, and when

  15. Integrated Social and Quality of Service Trust Management of Mobile Groups in Ad Hoc Networks

    Science.gov (United States)

    2013-01-01

    high resiliency to malicious attacks and misbehaving nodes. Keywords—trust management; mobile ad hoc networks; QoS trust; social trust; trust...paper we address an importance issue of trust management protocol design for MANETs: trust bias minimization despite misbehaving nodes performing

  16. Post hoc subgroups in clinical trials: Anathema or analytics?

    Science.gov (United States)

    Weisberg, Herbert I; Pontes, Victor P

    2015-08-01

    There is currently much interest in generating more individualized estimates of treatment effects. However, traditional statistical methods are not well suited to this task. Post hoc subgroup analyses of clinical trials are fraught with methodological problems. We suggest that the alternative research paradigm of predictive analytics, widely used in many business contexts, can be adapted to help. We compare the statistical and analytics perspectives and suggest that predictive modeling should often replace subgroup analysis. We then introduce a new approach, cadit modeling, that can be useful to identify and test individualized causal effects. The cadit technique is particularly useful in the context of selecting from among a large number of potential predictors. We describe a new variable-selection algorithm that has been applied in conjunction with cadit. The cadit approach is illustrated through a reanalysis of data from the Randomized Aldactone Evaluation Study trial, which studied the efficacy of spironolactone in heart-failure patients. The trial was successful, but a serious adverse effect (hyperkalemia) was subsequently discovered. Our reanalysis suggests that it may be possible to predict the degree of hyperkalemia based on a logistic model and to identify a subgroup in which the effect is negligible. Cadit modeling is a promising alternative to subgroup analyses. Cadit regression is relatively straightforward to implement, generates results that are easy to present and explain, and can mesh straightforwardly with many variable-selection algorithms. © The Author(s) 2015.

  17. Impact of Beamforming on the Path Connectivity in Cognitive Radio Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Le The Dung

    2017-03-01

    Full Text Available This paper investigates the impact of using directional antennas and beamforming schemes on the connectivity of cognitive radio ad hoc networks (CRAHNs. Specifically, considering that secondary users use two kinds of directional antennas, i.e., uniform linear array (ULA and uniform circular array (UCA antennas, and two different beamforming schemes, i.e., randomized beamforming and center-directed to communicate with each other, we study the connectivity of all combination pairs of directional antennas and beamforming schemes and compare their performances to those of omnidirectional antennas. The results obtained in this paper show that, compared with omnidirectional transmission, beamforming transmission only benefits the connectivity when the density of secondary user is moderate. Moreover, the combination of UCA and randomized beamforming scheme gives the highest path connectivity in all evaluating scenarios. Finally, the number of antenna elements and degree of path loss greatly affect path connectivity in CRAHNs.

  18. Improved AODV route recovery in mobile ad-hoc networks using a genetic algorithm

    Directory of Open Access Journals (Sweden)

    Ahmad Maleki

    2014-09-01

    Full Text Available An important issue in ad-hoc on-demand distance vector (AODV routing protocols is route failure caused by node mobility in the MANETs. The AODV requires a new route discovery procedure whenever a route breaks and these frequent route discoveries increase transmission delays and routing overhead. The present study proposes a new method for AODVs using a genetic algorithm to improve the route recovery mechanism. When failure occurs in a route, the proposed method (GAAODV makes decisions regarding the QOS parameter to select source or local repair. The task of the genetic algorithm is to find an appropriate combination of weights to optimize end-to-end delay. This paper evaluates the metrics of routing overhead, average end-to-end delay, and packet delivery ratio. Comparison of the new algorithm and AODV (RFC 3561 using a NS-2 simulator shows that GAAODV obtains better results for the QOS parameters.

  19. Ad Hoc Microphone Array Beamforming Using the Primal-Dual Method of Multipliers

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Heusdens, Richard

    2016-01-01

    In the recent years, there have been increasing amount of researches aiming at optimal beamforming with ad hoc microphone arrays, mostly with fusion-based schemes. However, huge amount of computational complexity and communication overhead impede many of these algorithms from being useful in prac...... the distributed linearly-constrained minimum variance beamformer using the the state of the art primal-dual method of multipliers. We study the proposed algorithm with an experiment....

  20. Protocolo W2LAN para transformar una red móvil 802.11 Ad-Hoc (MANET) en una LAN Ethernet

    OpenAIRE

    Burrull I Mestres, Francesco; García Haro, Juan; Malgosa Sanahuja, José María; Monzó Sánchez, Francisco Miguel

    2005-01-01

    Las redes MANET (Mobile Ad-Hoc Network) presentan el problema de la visibilidad parcial [1], por lo que hay que considerar protocolos de encaminamiento de nivel de enlace (capa 2 OSI) o superior. Algunos ejemplos de protocolos de encaminamiento en uso podrían ser el protocolo AODV (Ad Hoc On-demand Distance Vector[2]) -reactivo- y DSDV (Destination-Sequenced Distance Vector [3]) -proactivo-. En [4] se puede encontrar una comparativa extensa sobre protocolos de encaminamiento en redes MANET, o...

  1. A Routing Strategy for Non-Cooperation Wireless Multi-Hop Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Dung T. Tran

    2012-01-01

    Full Text Available Choosing routes such that the network lifetime is maximized in a wireless network with limited energy resources is a major routing problem in wireless multi-hop ad hoc networks. In this paper, we study the problem where participants are rationally selfish and non-cooperative. By selfish we designate the users who are ready to tamper with their source-routing (senders could choose intermediate nodes in the routing paths or next hop selection strategies in order to increase the total number of packets transmitted, but do not try to harm or drop packets of the other nodes. The problem therefore amounts to a non-cooperative game. In the works [2,6,19,23], the authors show that the game admits Nash equilibria [1]. Along this line, we first show that if the cost function is linear, this game has pure-strategy equilibrium flow even though participants have different demands. However, finding a Nash equilibrium for a normal game is computationally hard [9]. In this work, inspired by mixed-strategy equilibrium, we propose a simple local routing algorithm called MIxed Path Routing protocol (MiPR. Using analysis and simulations, we show that MiPR drives the system to an equilibrium state where selfish participants do not have incentive to deviate. Moreover, MiPR significantly improves the network lifetime as compared to original routing protocols.

  2. Ad hoc committee on reactor physics benchmarks

    International Nuclear Information System (INIS)

    Diamond, D.J.; Mosteller, R.D.; Gehin, J.C.

    1996-01-01

    In the spring of 1994, an ad hoc committee on reactor physics benchmarks was formed under the leadership of two American Nuclear Society (ANS) organizations. The ANS-19 Standards Subcommittee of the Reactor Physics Division and the Computational Benchmark Problem Committee of the Mathematics and Computation Division had both seen a need for additional benchmarks to help validate computer codes used for light water reactor (LWR) neutronics calculations. Although individual organizations had employed various means to validate the reactor physics methods that they used for fuel management, operations, and safety, additional work in code development and refinement is under way, and to increase accuracy, there is a need for a corresponding increase in validation. Both organizations thought that there was a need to promulgate benchmarks based on measured data to supplement the LWR computational benchmarks that have been published in the past. By having an organized benchmark activity, the participants also gain by being able to discuss their problems and achievements with others traveling the same route

  3. Investigating CSI: portrayals of DNA testing on a forensic crime show and their potential effects.

    Science.gov (United States)

    Ley, Barbara L; Jankowski, Natalie; Brewer, Paul R

    2012-01-01

    The popularity of forensic crime shows such as CSI has fueled debate about their potential social impact. This study considers CSI's potential effects on public understandings regarding DNA testing in the context of judicial processes, the policy debates surrounding crime laboratory procedures, and the forensic science profession, as well as an effect not discussed in previous accounts: namely, the show's potential impact on public understandings of DNA and genetics more generally. To develop a theoretical foundation for research on the "CSI effect," it draws on cultivation theory, social cognitive theory, and audience reception studies. It then uses content analysis and textual analysis to illuminate how the show depicts DNA testing. The results demonstrate that CSI tends to depict DNA testing as routine, swift, useful, and reliable and that it echoes broader discourses about genetics. At times, however, the show suggests more complex ways of thinking about DNA testing and genetics.

  4. Specification and Validation of an Edge Router Discovery Protocol for Mobile Ad Hoc Networks

    DEFF Research Database (Denmark)

    Kristensen, Lars Michael; Jensen, Kurt

    2004-01-01

    We present an industrial project at Ericsson Telebit A/S where Coloured Petri Nets (CP-nets or CPNs) have been used for the design and specification of an edge router discovery protocol for mobile ad-hoc networks. The Edge Router Discovery Protocol (ERDP) supports an edge router in a stationary...

  5. Impact of mobility on the performance of relaying in ad hoc networks (Extended version)

    NARCIS (Netherlands)

    Al Hanbali, A.; Kherani, A.A.; Groenevelt, R.; Nain, P.; Altman, E.

    2007-01-01

    We consider a mobile ad hoc network consisting of three types of nodes: source, destination, and relay nodes. All the nodes are moving over a bounded region with possibly different mobility patterns. We introduce and study the notion of relay throughput, i.e. the maximum rate at which a node can

  6. BLESSED with Opportunistic Beacons: A Lightweight Data Dissemination Model for Smart Mobile Ad-Hoc Networks

    NARCIS (Netherlands)

    Türkes, Okan; Scholten, Johan; Havinga, Paul J.M.

    2015-01-01

    This paper introduces BLESSED, a universal opportunistic ad hoc networking model intended for smart mobile devices. It enables fast and lightweight data dissemination in wireless community networks through the complementary utilization of the IEEE 802.11 and Bluetooth Low Energy standards. As a

  7. System optimization for peer-to-peer multi hop video broadcasting in wireless ad hoc networks

    NARCIS (Netherlands)

    Dedeoglu, V.; Atici, C.; Salman, F.S.; Sunay, M.O.

    2008-01-01

    We consider peer-to-peer video broadcasting using cooperation among peers in an ad hoc wireless network. As opposed to the traditional single hop broadcasting, multiple hops cause an increase in broadcast video quality while creating interference and increasing transmission delay. We develop

  8. Mobile agents affect worm spreading in wireless ad hoc networks

    International Nuclear Information System (INIS)

    Huang, Zi-Gang; Sun, Jin-Tu; Wang, Ying-Hai; Wang, Sheng-Jun; Xu, Xin-Jian

    2009-01-01

    Considering the dynamic nature of portable computing devices with wireless communication capability, an extended model is introduced for worm spreading in the wireless ad hoc network, with a population of mobile agents in a planar distribution, starting from an initial infected seed. The effect of agents' mobility on worm spreading is investigated via extensive Monte Carlo simulations. The threshold behavior and the dynamics of worm epidemics in the wireless networks are greatly affected by both agents' mobility and spatial and temporal correlations. The medium access control mechanism for the wireless communication promotes the sensitivity of the spreading dynamics to agents' mobility

  9. Enhanced Secure Trusted AODV (ESTA Protocol to Mitigate Blackhole Attack in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Dilraj Singh

    2015-09-01

    Full Text Available The self-organizing nature of the Mobile Ad hoc Networks (MANETs provide a communication channel anywhere, anytime without any pre-existing network infrastructure. However, it is exposed to various vulnerabilities that may be exploited by the malicious nodes. One such malicious behavior is introduced by blackhole nodes, which can be easily introduced in the network and, in turn, such nodes try to crumble the working of the network by dropping the maximum data under transmission. In this paper, a new protocol is proposed which is based on the widely used Ad hoc On-Demand Distance Vector (AODV protocol, Enhanced Secure Trusted AODV (ESTA, which makes use of multiple paths along with use of trust and asymmetric cryptography to ensure data security. The results, based on NS-3 simulation, reveal that the proposed protocol is effectively able to counter the blackhole nodes in three different scenarios.

  10. Ad-hoc Network of Smart Sensors for Mechanical Load Measurement

    Directory of Open Access Journals (Sweden)

    Manuel A. Vieira

    2016-07-01

    Full Text Available Strain gauges load cells are transducers devices capable of converting changes in applied mechanical load into an electrical analog signal. Those devices have a large spectrum of applications ranging from domestic to industrial or even medical appliances just to name a few. In this work, they are used in the electronic instrumentation of a force platform that will be used to carry out the analysis and characterization of human biomechanical walking. In this platform, four load cells are installed, each one capable of measuring forces along two different axis. A total of eight strain-gauges per load cell are employed. Hence, analog signal transmission, besides requiring a large number of connection wires, is prone to interference and noise. Moreover, with this solution, scalability requires severe changes in the connection topology. In order to circumvent those problems, an alternative in-situ signal conditioning and digital data transmission system was devised. This approach, as far as investigated, presents an innovative solution to signal conditioning and data transmission for load-cells. In particular, the presented solution allows the creation of an ad-hoc network of load cells, using the I²C protocol with a master interface that allows the users to interact and change the parameters of each load cell. This instrumentation structure has been successfully tested and the obtained results are documented in this article.

  11. Real-Time Support on IEEE 802.11 Wireless Ad-Hoc Networks: Reality vs. Theory

    Science.gov (United States)

    Kang, Mikyung; Kang, Dong-In; Suh, Jinwoo

    The usable throughput of an IEEE 802.11 system for an application is much less than the raw bandwidth. Although 802.11b has a theoretical maximum of 11Mbps, more than half of the bandwidth is consumed by overhead leaving at most 5Mbps of usable bandwidth. Considering this characteristic, this paper proposes and analyzes a real-time distributed scheduling scheme based on the existing IEEE 802.11 wireless ad-hoc networks, using USC/ISI's Power Aware Sensing Tracking and Analysis (PASTA) hardware platform. We compared the distributed real-time scheduling scheme with the real-time polling scheme to meet deadline, and compared a measured real bandwidth with a theoretical result. The theoretical and experimental results show that the distributed scheduling scheme can guarantee real-time traffic and enhances the performance up to 74% compared with polling scheme.

  12. Quorum system and random based asynchronous rendezvous protocol for cognitive radio ad hoc networks

    Directory of Open Access Journals (Sweden)

    Sylwia Romaszko

    2013-12-01

    Full Text Available This paper proposes a rendezvous protocol for cognitive radio ad hoc networks, RAC2E-gQS, which utilizes (1 the asynchronous and randomness properties of the RAC2E protocol, and (2 channel mapping protocol, based on a grid Quorum System (gQS, and taking into account channel heterogeneity and asymmetric channel views. We show that the combination of the RAC2E protocol with the grid-quorum based channel mapping can yield a powerful RAC2E-gQS rendezvous protocol for asynchronous operation in a distributed environment assuring a rapid rendezvous between the cognitive radio nodes having available both symmetric and asymmetric channel views. We also propose an enhancement of the protocol, which uses a torus QS for a slot allocation, dealing with the worst case scenario, a large number of channels with opposite ranking lists.

  13. An Incentivized Approach for Fair Participation in Wireless Ad hoc Networks

    OpenAIRE

    Choudhuri, Arka Rai; S, Kalyanasundaram; Sridhar, Shriyak; B, Annappa

    2015-01-01

    In Wireless Ad hoc networks (WANETs), nodes separated by considerable distance communicate with each other by relaying their messages through other nodes. However, it might not be in the best interests of a node to forward the message of another node due to power constraints. In addition, all nodes being rational, some nodes may be selfish, i.e. they might not relay data from other nodes so as to increase their lifetime. In this paper, we present a fair and incentivized approach for participa...

  14. Performance Analysis of a Cluster-Based MAC Protocol for Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Jesús Alonso-Zárate

    2010-01-01

    Full Text Available An analytical model to evaluate the non-saturated performance of the Distributed Queuing Medium Access Control Protocol for Ad Hoc Networks (DQMANs in single-hop networks is presented in this paper. DQMAN is comprised of a spontaneous, temporary, and dynamic clustering mechanism integrated with a near-optimum distributed queuing Medium Access Control (MAC protocol. Clustering is executed in a distributed manner using a mechanism inspired by the Distributed Coordination Function (DCF of the IEEE 802.11. Once a station seizes the channel, it becomes the temporary clusterhead of a spontaneous cluster and it coordinates the peer-to-peer communications between the clustermembers. Within each cluster, a near-optimum distributed queuing MAC protocol is executed. The theoretical performance analysis of DQMAN in single-hop networks under non-saturation conditions is presented in this paper. The approach integrates the analysis of the clustering mechanism into the MAC layer model. Up to the knowledge of the authors, this approach is novel in the literature. In addition, the performance of an ad hoc network using DQMAN is compared to that obtained when using the DCF of the IEEE 802.11, as a benchmark reference.

  15. Sigsearch: a new term for post hoc unplanned search for statistically significant relationships with the intent to create publishable findings.

    Science.gov (United States)

    Hashim, Muhammad Jawad

    2010-09-01

    Post-hoc secondary data analysis with no prespecified hypotheses has been discouraged by textbook authors and journal editors alike. Unfortunately no single term describes this phenomenon succinctly. I would like to coin the term "sigsearch" to define this practice and bring it within the teaching lexicon of statistics courses. Sigsearch would include any unplanned, post-hoc search for statistical significance using multiple comparisons of subgroups. It would also include data analysis with outcomes other than the prespecified primary outcome measure of a study as well as secondary data analyses of earlier research.

  16. Regressive research: The pitfalls of post hoc data selection in the study of unconscious mental processes.

    Science.gov (United States)

    Shanks, David R

    2017-06-01

    Many studies of unconscious processing involve comparing a performance measure (e.g., some assessment of perception or memory) with an awareness measure (such as a verbal report or a forced-choice response) taken either concurrently or separately. Unconscious processing is inferred when above-chance performance is combined with null awareness. Often, however, aggregate awareness is better than chance, and data analysis therefore employs a form of extreme group analysis focusing post hoc on participants, trials, or items where awareness is absent or at chance. The pitfalls of this analytic approach are described with particular reference to recent research on implicit learning and subliminal perception. Because of regression to the mean, the approach can mislead researchers into erroneous conclusions concerning unconscious influences on behavior. Recommendations are made about future use of post hoc selection in research on unconscious cognition.

  17. PERFORMANCE ANALYSIS OF DSR ROUTING PROTOCOL UNDER ENERGY BASED SELFISH ATTACK IN MOBILE AD HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    T.V.P.Sundararajan

    2010-06-01

    Full Text Available Mobile Ad hoc Networks (MANETs rely on the cooperation of all participating nodes to provide the fundamental operations such as routing and data forwarding. However, due to the open structure and scarcely available battery-based energy, node misbehaviors may exist.[1]. One such routing misbehavior is that some selfish nodes will participate in the route discovery and maintenance processes but refuse to forward data packets. This paper pointed out Energy based selfish nodes (EBSN where these selfish nodes tend to use the network but do not cooperate, saving battery life for their own communications [2],[3]. We present a simulation study of the effects of Energy based selfish nodes (EBSN on DSR routing protocol and its impact over network performance in terms of throughput and delay of a mobile ad hoc network where a defined percentage of nodes were misbehaving.

  18. PROTOCOLS FOR INCREASING THE LIFETIME OF NODES OF AD HOC WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    B.Malarkodi

    2010-03-01

    Full Text Available Power consumption of nodes in ad hoc networks is a critical issue as they predominantly operate on batteries. In order to improve the lifetime of an ad hoc network, all the nodes must be utilized evenly and the power required for connections must be minimized. Energy management deals with the process of managing energy resources by means of controlling the battery discharge, adjusting the transmission power and scheduling of power sources so as to increase the lifetime of the nodes of an ad hoc wireless network. In this paper, two protocols are proposed to improve the lifetime of the nodes. The first protocol assumes smart battery packages with L cells and uses dynamic programming (DP to optimally select the set of cells used to satisfy a request for power. The second one proposes a MAC layer protocol denoted as Power Aware medium Access Control (PAMAC protocol which enables the network layer to select a route with minimum total power requirement among the possible routes between a source and a destination provided all nodes in the routes have battery capacity above a threshold. The life time of the nodes using the DP based scheduling policy is found through simulation and compared with that obtained using the techniques reported in the literature. It is found that DP based policy increases the lifetime of the mobile nodes by a factor of 1.15 to 1.8. The life expectancy, the average power consumption and throughput of the network using PAMAC protocol are computed through simulation and compared with that of the other MAC layer protocols 802.11, MACA, and CSMA. Besides this, the life expectancy and average power consumption of the network for different values of threshold are also compared. From the simulation results, it is observed that PAMAC consumes the least power and provides the longest lifetime among the various MAC Layer protocols. Moreover, using PAMAC as the MAC layer protocol, the performance obtained using different routing layer

  19. Comunicaciones seguras sobre redes móviles ad hoc

    OpenAIRE

    Rocabado Moreno, Sergio Hernán; Arias Figueroa, Daniel; Sánchez, Ernesto

    2011-01-01

    En este proyecto se ha planteado investigar diferentes mecanismos para realizar comunicaciones seguras utilizando redes móviles ad-hoc, esto permitirá aprovechar las características inherentes de este tipo de redes, para llevar información crítica de forma segura a lugares donde no se disponga de acceso a redes de infraestructura. El resultado final será una propuesta que servirá de base para el desarrollo e implementación de sistemas móviles para emergencias médicas y también como material d...

  20. A Partitioned Approach to Signal Separation with Microphone Ad Hoc Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Benesty, Jacob

    2016-01-01

    In this paper, a blind algorithm is proposed for speech enhancement in multi-speaker scenarios, in which interference rejection is the main objective. Here, the ad hoc array is broken into microphone duples which are used to partition the array into local sub-arrays. The core algorithm takes...... advantage of differences in signal structure in each duple. A geometric mean filter is then used to merge the output signals obtained with different duples, and to form a global broadband maximum signal-to-interference ratio (SIR) enhancement apparatus. The resulting filter outputs are enhanced acoustic...

  1. Increased longevity of wireless Ad hoc network through fuzzy system

    Directory of Open Access Journals (Sweden)

    Fawzia Abdali Larki

    2014-06-01

    Full Text Available The Ad hoc network is one of the multistep-based self-organizing networks, which are dynamically changing and are taken more into account as the ways of connecting the terminals through the development of wireless communication terminals. We are faced with numerous challenges in designing a wireless network such as the dynamic topology, common and limited bandwidth, and the limited energy. The nodes are moving according to the continuous changes in the topology and the source-to-destination paths are completely broken. Therefore, the repeated route discovery enhances the delay and overload of routing. Thus, it is essential to consider the link stability while designing the path in order to choose the routing protocol. Providing the multiple paths may lead to the better performance than a path. The transmission energy control in the wireless Ad hoc networks is the option for the level of transmission energy in order to transmit each node packet in this system. Therefore, transmission energy control affects the wireless medium interface. Because of choosing the appropriate protocol, the routing operation can be improved and the energy consumption can be controlled properly as well as enhancing the durability and longevity of network. The main objective of this study is to enhance the network longevity. The proposed algorithm in this research considers the combination of 2 parameters including the rate of node energy and number of steps in Fuzzy System applied on AOMDV Protocol, which is a Multipath Routing Protocol. The results of simulation also indicate the improved performance of proposed algorithm (AOMDV-F compared to AODV and AOMDV Protocols in NS2 simulator.

  2. A Bioinspired Adaptive Congestion-Avoidance Routing for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Huang Qiong

    2014-01-01

    Full Text Available Traditional mobile Ad Hoc network routing protocols are mainly based on the Shortest Path, which possibly results in many congestion nodes that incur routing instability and rerouting. To mitigate the side-efforts, this paper proposed a new bioinspired adaptive routing protocol (ATAR based on a mathematics biology model ARAS. This paper improved the ARAS by reducing the randomness and by introducing a new routing-decision metric “the next-hop fitness” which was denoted as the congestion level of node and the length of routing path. In the route maintenance, the nodes decide to forward the data to next node according to a threshold value of the fitness. In the recovery phase, the node will adopt random manner to select the neighbor as the next hop by calculation of the improved ARAS. With this route mechanism, the ATAR could adaptively circumvent the congestion nodes and the rerouting action is taken in advance. Theoretical analysis and numerical simulation results show that the ATAR protocol outperforms AODV and MARAS in terms of delivery ratio, ETE delay, and the complexity. In particular, ATAR can efficiently mitigate the congestion.

  3. ARSENAL: A Cross Layer Architecture for Secure Resilient Tactical Mobile AdHoc Networks

    Science.gov (United States)

    2016-01-21

    stations separated by 0.5 to 1 km can be coherently measured to a single mobile subscriber using LTE signaling. These are the first measurements of...undertake three parallel but inter-coupled tasks geared towards a) performing measurements via real deployments and enhancing our understanding of layer...dependencies and vulnerabilities in mobile ad hoc networks; these measurements will be on existing testbeds at The views, opinions and/or findings

  4. MQARR-AODV: A NOVEL MULTIPATH QOS AWARE RELIABLE REVERSE ON-DEMAND DISTANCE VECTOR ROUTING PROTOCOL FOR MOBILE AD-HOC NETWORKS

    Directory of Open Access Journals (Sweden)

    K.G. Santhiya

    2012-12-01

    Full Text Available MANET (Mobile Ad-hoc Network is an infra structure less wireless ad-hoc network that does not require any basic central control. The topology of the network changes drastically due to very fast mobility of nodes. So an adaptive routing protocol is needed for routing in MANET. AODV (Ad-hoc On-demand Distance Vector routing is the effective and prominent on-demand Ad-hoc routing protocols. During route establishment phase in traditional AODV, only one route reply message will be sent in the reverse path to establish routing path. The high mobility of nodes may affect the reply messages which lead to the retransmission of route request message by the sender which in turn leads to higher communication delay, power consumption and the reduction in the ratio of packets delivered. Sending multiple route reply messages and establishing multiple paths in a single path discovery will reduce the routing overhead involved in maintaining the connection between source and destination nodes. Multipath routing can render high scalability, end-to-end throughput and provide load balancing in MANET. The new proposed novel Multipath QoS aware reliable routing protocol establishes two routes of maximum node disjoint paths and the data transfer is carried out in the two paths simultaneously. To select best paths, the new proposed protocol uses three parameters Link Eminence, MAC overhead and node residual energy. The experimental values prove that the MQARR-AODV protocol achieves high reliability, stability, low latency and outperforms AODV by the less energy consumption, overhead and delay.

  5. T-UPPAAL: Online Model-based Testing of Real-Time Systems

    DEFF Research Database (Denmark)

    Mikucionis, Marius; Larsen, Kim Guldstrand; Nielsen, Brian

    2004-01-01

    The goal of testing is to gain confidence in a physical computer based system by means of executing it. More than one third of typical project resources is spent on testing embedded and real-time systems, but still it remains ad-hoc, based on heuristics, and error-prone. Therefore systematic...

  6. Neuroprotection as initial therapy in acute stroke - Third report of an Ad Hoc Consensus Group Meeting

    NARCIS (Netherlands)

    Bogousslavsky, J; De Keyser, J; Diener, HC; Fieschi, C; Hacke, W; Kaste, M; Orgogozo, JM; Pulsinelli, W; Wahlgren, NG

    1998-01-01

    Although a considerable body of scientific data is now available on neuroprotection in acute ischaemic stroke, this field is not yet established in clinical practice. At its third meeting, the European Ad Hoc Consensus Group considered the potential for neuroprotection in acute stroke and the

  7. The doctrine of joint criminal action in the ad hoc tribunals and its scope in the Rome Statute

    Directory of Open Access Journals (Sweden)

    Miren Odriozola-Gurrutxaga

    2014-03-01

    Full Text Available The first judgment of the International Criminal Court has confirmed that article 25 (3 of the Rome Statute adopts the theory of control of the act to distinguish between principals and accessories. On the contrary, since 2003, the ad hoc tribunals’ case law bases the notion of co-perpetration on the Joint Criminal Enterprise doctrine, using a subjective criterion approach. In this article we will first analyze the problems raised by that case law of the ad hoc tribunals, and then, we will study the article of the Rome Statute which apparently most resembles the Joint Criminal Enterprise doctrine: article 25 (3 (d. The article concludes that none of the three categories of that doctrine is included in the said provision.

  8. Post hoc analysis of Japanese patients from the placebo-controlled PREVAIL trial of enzalutamide in patients with chemotherapy-naive, metastatic castration-resistant prostate cancer—updated results

    Science.gov (United States)

    Ueda, Takeshi

    2017-01-01

    Abstract A post hoc analysis of interim results from PREVAIL, a Phase III, double-blind, placebo-controlled trial of men with metastatic castration-resistant prostate cancer, demonstrated that the treatment effects, safety and pharmacokinetics of enzalutamide in Japanese patients were generally consistent with those of the overall population. A recent longer term analysis of PREVAIL demonstrated continued benefit of enzalutamide treatment over placebo. Here, we report results from a post hoc analysis of Japanese patients enrolled in PREVAIL at the prespecified number of deaths for the final analysis. In Japanese patients, enzalutamide reduced the risk of death by 35% (hazard ratio, 0.65; 95% confidence interval, 0.28–1.51) and the risk of investigator-assessed radiographic progression or death by 60% (hazard ratio, 0.40; 95% confidence interval, 0.18–0.90). These results show that treatment effects and safety in Japanese patients in the final analysis of PREVAIL continued to be generally consistent with those of the overall population. PMID:28003320

  9. Secure and Usable Out-Of-Band Channels for Ad Hoc Mobile Device Interactions

    OpenAIRE

    Kainda , Ronald; Flechais , Ivan; Roscoe , A. W.

    2010-01-01

    International audience; Protocols for bootstrapping security in ad hoc mobile device interactions rely on users' ability to perform specific tasks such as transferring or comparing fingerprints of information between devices. The size of fingerprints depends on the level of technical security required by a given application but, at the same time, is limited by users' inability to deal with large amounts of data with high levels of accuracy. Large fingerprints provide high technical security b...

  10. Ad hoc supervision of general practice registrars as a 'community of practice': analysis, interpretation and re-presentation.

    Science.gov (United States)

    Clement, T; Brown, J; Morrison, J; Nestel, D

    2016-05-01

    General practice registrars in Australia undertake most of their vocational training in accredited general practices. They typically see patients alone from the start of their community-based training and are expected to seek timely ad hoc support from their supervisor. Such ad hoc encounters are a mechanism for ensuring patient safety, but also provide an opportunity for learning and teaching. Wenger's (Communities of practice: learning, meaning, and identity. Cambridge University Press, New York, 1998) social theory of learning ('communities of practice') guided a secondary analysis of audio-recordings of ad hoc encounters. Data from one encounter is re-presented as an extended sequence to maintain congruence with the theoretical perspective and enhance vicariousness. An interpretive commentary communicates key features of Wenger's theory and highlights the researchers' interpretations. We argue that one encounter can reveal universal understandings of clinical supervision and that the process of naturalistic generalisation allows readers to transfer others' experiences to their own contexts. The paper raises significant analytic, interpretive, and representational issues. We highlight that report writing is an important, but infrequently discussed, part of research design. We discuss the challenges of supporting the learning and teaching that arises from adopting a socio-cultural lens and argue that such a perspective importantly captures the complex range of issues that work-based practitioners have to grapple with. This offers a challenge to how we research and seek to influence work-based learning and teaching in health care settings.

  11. 3VSR: Three Valued Secure Routing for Vehicular Ad Hoc Networks using Sensing Logic in Adversarial Environment

    Directory of Open Access Journals (Sweden)

    Muhammad Sohail

    2018-03-01

    Full Text Available Today IoT integrate thousands of inter networks and sensing devices e.g., vehicular networks, which are considered to be challenging due to its high speed and network dynamics. The goal of future vehicular networks is to improve road safety, promote commercial or infotainment products and to reduce the traffic accidents. All these applications are based on the information exchange among nodes, so not only reliable data delivery but also the authenticity and credibility of the data itself are prerequisite. To cope with the aforementioned problem, trust management come up as promising candidate to conduct node’s transaction and interaction management, which requires distributed mobile nodes cooperation for achieving design goals. In this paper, we propose a trust-based routing protocol i.e., 3VSR (Three Valued Secure Routing, which extends the widely used AODV (Ad hoc On-demand Distance Vector routing protocol and employs the idea of Sensing Logic-based trust model to enhance the security solution of VANET (Vehicular Ad-Hoc Network. The existing routing protocol are mostly based on key or signature-based schemes, which off course increases computation overhead. In our proposed 3VSR, trust among entities is updated frequently by means of opinion derived from sensing logic due to vehicles random topologies. In 3VSR the theoretical capabilities are based on Dirichlet distribution by considering prior and posterior uncertainty of the said event. Also by using trust recommendation message exchange, nodes are able to reduce computation and routing overhead. The simulated results shows that the proposed scheme is secure and practical.

  12. 3VSR: Three Valued Secure Routing for Vehicular Ad Hoc Networks using Sensing Logic in Adversarial Environment.

    Science.gov (United States)

    Sohail, Muhammad; Wang, Liangmin

    2018-03-14

    Today IoT integrate thousands of inter networks and sensing devices e.g., vehicular networks, which are considered to be challenging due to its high speed and network dynamics. The goal of future vehicular networks is to improve road safety, promote commercial or infotainment products and to reduce the traffic accidents. All these applications are based on the information exchange among nodes, so not only reliable data delivery but also the authenticity and credibility of the data itself are prerequisite. To cope with the aforementioned problem, trust management come up as promising candidate to conduct node's transaction and interaction management, which requires distributed mobile nodes cooperation for achieving design goals. In this paper, we propose a trust-based routing protocol i.e., 3VSR (Three Valued Secure Routing), which extends the widely used AODV (Ad hoc On-demand Distance Vector) routing protocol and employs the idea of Sensing Logic-based trust model to enhance the security solution of VANET (Vehicular Ad-Hoc Network). The existing routing protocol are mostly based on key or signature-based schemes, which off course increases computation overhead. In our proposed 3VSR, trust among entities is updated frequently by means of opinion derived from sensing logic due to vehicles random topologies. In 3VSR the theoretical capabilities are based on Dirichlet distribution by considering prior and posterior uncertainty of the said event. Also by using trust recommendation message exchange, nodes are able to reduce computation and routing overhead. The simulated results shows that the proposed scheme is secure and practical.

  13. Panel Discussion : Report of the APS Ad-Hoc Committee on LGBT Issues

    Science.gov (United States)

    Atherton, Tim; Barthelemy, Ramon; Garmon, Savannah; Reeves, Kyle; APS Ad-Hoc Committee on LGBT Issues Team

    Following the presentation of the findings and recommendations of the APS Ad-Hoc Committee on LGBT Issues (C-LGBT) by Committee Chair Michael Falk, a panel discussion will be held featuring several members of the committee. The discussion will focus on how APS can best ensure the recommendations of the committee are carried out in a timely fashion and other ideas on future APS efforts toward LGBT inclusion in physics. Discussion topics will also include the research and other input that shaped the committee's findings and recommendations.

  14. Vehicular ad hoc networks standards, solutions, and research

    CERN Document Server

    Molinaro, Antonella; Scopigno, Riccardo

    2015-01-01

    This book presents vehicular ad-hoc networks (VANETs) from the their onset, gradually going into technical details, providing a clear understanding of both theoretical foundations and more practical investigation. The editors gathered top-ranking authors to provide comprehensiveness and timely content; the invited authors were carefully selected from a list of who’s who in the respective field of interest: there are as many from Academia as from Standardization and Industry sectors from around the world. The covered topics are organized around five Parts starting from an historical overview of vehicular communications and standardization/harmonization activities (Part I), then progressing to the theoretical foundations of VANETs and a description of the day-one standard-compliant solutions (Part II), hence going into details of vehicular networking and security (Part III) and to the tools to study VANETs, from mobility and channel models, to network simulators and field trial methodologies (Part IV), and fi...

  15. Data management issues in mobile ad hoc networks.

    Science.gov (United States)

    Hara, Takahiro

    2017-01-01

    Research on mobile ad hoc networks (MANETs) has become a hot research topic since the middle 1990's. Over the first decade, most research focused on networking techniques, ignoring data management issues. We, however, realized early the importance of data management in MANETs, and have been conducting studies in this area for 15 years. In this review, we summarize some key technical issues related to data management in MANETs, and the studies we have done in addressing these issues, which include placement of data replicas, update management, and query processing with security management. The techniques proposed in our studies have been designed with deep considerations of MANET features including network partitioning, node participation/disappearance, limited network bandwidth, and energy efficiency. Our studies published in early 2000's have developed a new research field as data management in MANETs. Also, our recent studies are expected to be significant guidelines of new research directions. We conclude the review by discussing some future directions for research.

  16. Verifying Safety Messages Using Relative-Time and Zone Priority in Vehicular Ad Hoc Networks

    Science.gov (United States)

    Banani, Sam; Thiemjarus, Surapa; Kittipiyakul, Somsak

    2018-01-01

    In high-density road networks, with each vehicle broadcasting multiple messages per second, the arrival rate of safety messages can easily exceed the rate at which digital signatures can be verified. Since not all messages can be verified, algorithms for selecting which messages to verify are required to ensure that each vehicle receives appropriate awareness about neighbouring vehicles. This paper presents a novel scheme to select important safety messages for verification in vehicular ad hoc networks (VANETs). The proposed scheme uses location and direction of the sender, as well as proximity and relative-time between vehicles, to reduce the number of irrelevant messages verified (i.e., messages from vehicles that are unlikely to cause an accident). Compared with other existing schemes, the analysis results show that the proposed scheme can verify messages from nearby vehicles with lower inter-message delay and reduced packet loss and thus provides high level of awareness of the nearby vehicles. PMID:29652840

  17. Reduced sick leave in multiple sclerosis after one year of natalizumab treatment. A prospective ad hoc analysis of the TYNERGY trial.

    Science.gov (United States)

    Wickström, Anne; Dahle, Charlotte; Vrethem, Magnus; Svenningsson, Anders

    2014-07-01

    In a retrospective study, we have previously shown that work ability was improved after the initiation of natalizumab treatment in relapsing-remitting multiple sclerosis (RRMS). In another prospective trial (TYNERGY) the effect on MS-related fatigue was evaluated after 12 months of treatment with natalizumab. A comprehensive Capacity for Work Questionnaire (CWQ) was used to collect data regarding number of working hours and sickness absence. The predefined intention-to-treat analysis regarding work ability did not, however, show significant results. The objective of this paper is to assess the amount of sick leave in RRMS before and after one year of natalizumab treatment and correlate it to fatigue and walking ability. This is a post-hoc analysis of the complete data from the CWQ used in the TYNERGY trial. MS patients receiving sickness benefit before start of treatment reduced their sickness benefit by an absolute change of 33% after one year of natalizumab treatment. Younger age and improvement of walking ability correlated significantly with reduction of sick leave. This ad-hoc analysis of prospectively collected data supported our previous retrospective study and thus indicates a positive relationship between natalizumab treatment and improvement in work ability. © The Author(s) 2013.

  18. Intelligent self-organization methods for wireless ad hoc sensor networks based on limited resources

    Science.gov (United States)

    Hortos, William S.

    2006-05-01

    A wireless ad hoc sensor network (WSN) is a configuration for area surveillance that affords rapid, flexible deployment in arbitrary threat environments. There is no infrastructure support and sensor nodes communicate with each other only when they are in transmission range. To a greater degree than the terminals found in mobile ad hoc networks (MANETs) for communications, sensor nodes are resource-constrained, with limited computational processing, bandwidth, memory, and power, and are typically unattended once in operation. Consequently, the level of information exchange among nodes, to support any complex adaptive algorithms to establish network connectivity and optimize throughput, not only deplete those limited resources and creates high overhead in narrowband communications, but also increase network vulnerability to eavesdropping by malicious nodes. Cooperation among nodes, critical to the mission of sensor networks, can thus be disrupted by the inappropriate choice of the method for self-organization. Recent published contributions to the self-configuration of ad hoc sensor networks, e.g., self-organizing mapping and swarm intelligence techniques, have been based on the adaptive control of the cross-layer interactions found in MANET protocols to achieve one or more performance objectives: connectivity, intrusion resistance, power control, throughput, and delay. However, few studies have examined the performance of these algorithms when implemented with the limited resources of WSNs. In this paper, self-organization algorithms for the initiation, operation and maintenance of a network topology from a collection of wireless sensor nodes are proposed that improve the performance metrics significant to WSNs. The intelligent algorithm approach emphasizes low computational complexity, energy efficiency and robust adaptation to change, allowing distributed implementation with the actual limited resources of the cooperative nodes of the network. Extensions of the

  19. A Game Theory Based Approach for Power Efficient Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Kun Hua

    2017-01-01

    Full Text Available Green communications are playing critical roles in vehicular ad hoc networks (VANETs, while the deployment of a power efficient VANET is quite challenging in practice. To add more greens into such kind of complicated and time-varying mobile network, we specifically investigate the throughput and transmission delay performances for real-time and delay sensitive services through a repeated game theoretic solution. This paper has employed Nash Equilibrium in the noncooperative game model and analyzes its efficiency. Simulation results have shown an obvious improvement on power efficiency through such efforts.

  20. Implementation and Evaluation of Multichannel Multi-Interface Routing Mechanism with QoS-Consideration for Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    Satoh Hiroki

    2010-01-01

    Full Text Available To accommodate real-time multimedia application while satisfying application-level QoS requirements in a wireless ad-hoc network, we need QoS control mechanisms. We proposed a new routing mechanism for a wireless ad-hoc network composed of nodes equipped with multiple network interfaces. By embedding information about channel usage in control messages of OLSRv2, each node obtains a view of topology and bandwidth information of the whole network. Based on the obtained information, a source node determines a logical path with the maximum available bandwidth to satisfy application-level QoS requirements. In this paper, we evaluated feasibility of the proposal through simulation and practical experiments and confirmed that our proposal effectively transferred multimedia packets over a logical path avoiding congested links. The load on a network is well distributed and the network can accommodate more sessions than OLSRv2 and QOLSR.

  1. Impact of mobility on the performance7 of relaying in ad hoc networks – Extended version

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Kherani, A.A.; Groenevelt, R.; Nain, P.; Altman, E

    2007-01-01

    We consider a mobile ad hoc network consisting of three types of nodes: source, destination, and relay nodes. All the nodes are moving over a bounded region with possibly different mobility patterns. We introduce and study the notion of relay throughput, i.e. the maximum rate at which a node can

  2. Skeletal Muscle Differentiation on a Chip Shows Human Donor Mesoangioblasts' Efficiency in Restoring Dystrophin in a Duchenne Muscular Dystrophy Model.

    Science.gov (United States)

    Serena, Elena; Zatti, Susi; Zoso, Alice; Lo Verso, Francesca; Tedesco, F Saverio; Cossu, Giulio; Elvassore, Nicola

    2016-12-01

    : Restoration of the protein dystrophin on muscle membrane is the goal of many research lines aimed at curing Duchenne muscular dystrophy (DMD). Results of ongoing preclinical and clinical trials suggest that partial restoration of dystrophin might be sufficient to significantly reduce muscle damage. Different myogenic progenitors are candidates for cell therapy of muscular dystrophies, but only satellite cells and pericytes have already entered clinical experimentation. This study aimed to provide in vitro quantitative evidence of the ability of mesoangioblasts to restore dystrophin, in terms of protein accumulation and distribution, within myotubes derived from DMD patients, using a microengineered model. We designed an ad hoc experimental strategy to miniaturize on a chip the standard process of muscle regeneration independent of variables such as inflammation and fibrosis. It is based on the coculture, at different ratios, of human dystrophin-positive myogenic progenitors and dystrophin-negative myoblasts in a substrate with muscle-like physiological stiffness and cell micropatterns. Results showed that both healthy myoblasts and mesoangioblasts restored dystrophin expression in DMD myotubes. However, mesoangioblasts showed unexpected efficiency with respect to myoblasts in dystrophin production in terms of the amount of protein produced (40% vs. 15%) and length of the dystrophin membrane domain (210-240 µm vs. 40-70 µm). These results show that our microscaled in vitro model of human DMD skeletal muscle validated previous in vivo preclinical work and may be used to predict efficacy of new methods aimed at enhancing dystrophin accumulation and distribution before they are tested in vivo, reducing time, costs, and variability of clinical experimentation. This study aimed to provide in vitro quantitative evidence of the ability of human mesoangioblasts to restore dystrophin, in terms of protein accumulation and distribution, within myotubes derived from

  3. Structural effects of sprifermin in knee osteoarthritis: a post-hoc analysis on cartilage and non-cartilaginous tissue alterations in a randomized controlled trial.

    Science.gov (United States)

    Roemer, Frank W; Aydemir, Aida; Lohmander, Stefan; Crema, Michel D; Marra, Monica Dias; Muurahainen, Norma; Felson, David T; Eckstein, Felix; Guermazi, Ali

    2016-07-09

    A recent publication on efficacy of Sprifermin for knee osteoarthritis (OA) using quantitatively MRI-defined central medial tibio-femoral compartment cartilage thickness as the structural primary endpoint reported no statistically significant dose response. However, Sprifermin was associated with statistically significant, dose-dependent reductions in loss of total and lateral tibio-femoral cartilage thickness. Based on these preliminary promising data a post-hoc analysis of secondary assessment and endpoints was performed to evaluate potential effects of Sprifermin on semi-quantitatively evaluated structural MRI parameters. Aim of the present analysis was to determine effects of sprifermin on several knee joint tissues over a 12 month period. 1.5 T or 3 T MRIs were acquired at baseline and 12 months follow-up using a standard protocol. MRIs were read according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS) scoring system (in 14 articular subregions) by four muskuloskeletal radiologists independently. Analyses focused on semiquantitative changes in the 100 μg subgroup and matching placebo of multiple MRI-defined structural alterations. Analyses included a delta-subregional and delta-sum approach for the whole knee and the medial and lateral tibio-femoral (MTFJ, LTFJ), and patello-femoral (PFJ) compartments, taking into account number of subregions showing no change, improvement or worsening and changes in the sum of subregional scores. Mann-Whitney - Wilcoxon tests assessed differences between groups. Fifty-seven and 18 patients were included in the treatment and matched placebo subgroups. Less worsening of cartilage damage was observed from baseline to 12 months in the PFJ (0.02, 95 % confidence interval (CI) (-0.04, 0.08) vs. placebo 0.22, 95 % CI (-0.05, 0.49), p = 0.046). For bone marrow lesions (BMLs), more improvement was observed from 6 to 12 months for whole knee analyses (-0.14, 95 % CI (-0.48, 0.19) vs. placebo 0.44, 95

  4. Intelligent Networks Data Fusion Web-based Services for Ad-hoc Integrated WSNs-RFID

    Directory of Open Access Journals (Sweden)

    Falah Alshahrany

    2016-01-01

    Full Text Available The use of variety of data fusion tools and techniques for big data processing poses the problem of the data and information integration called data fusion having objectives which can differ from one application to another. The design of network data fusion systems aimed at meeting these objectives, need to take into account of the necessary synergy that can result from distributed data processing within the data networks and data centres, involving increased computation and communication. This papers reports on how this processing distribution is functionally structured as configurable integrated web-based support services, in the context of an ad-hoc wireless sensor network used for sensing and tracking, in the context of distributed detection based on complete observations to support real rime decision making. The interrelated functional and hardware RFID-WSN integration is an essential aspect of the data fusion framework that focuses on multi-sensor collaboration as an innovative approach to extend the heterogeneity of the devices and sensor nodes of ad-hoc networks generating a huge amount of heterogeneous soft and hard raw data. The deployment and configuration of these networks require data fusion processing that includes network and service management and enhances the performance and reliability of networks data fusion support systems providing intelligent capabilities for real-time control access and fire detection.

  5. Optimalization of Beacon Selection for Localization in Wireless AD-HOC Networks

    Directory of Open Access Journals (Sweden)

    Martin Matula

    2008-01-01

    Full Text Available In this paper we engage in optimalization of convenient beacons for localization position of a node in the ad-hoc network. An algorithm designed by us localizes position of moving or static node by RSS (Received Signal Strength method and trilateration. At first, localization of unknown node runs by combination of all beacons. Than optimalizating algorithmreduces the number of beacons (and repeats localization, while only three left. Its reduction is based on highest levels of received signal strength. It is only when signals are from the nearest beacons. Position localizating exactness is statistically interpreted from all localization by beacons combination and its repeating.

  6. Use of "t"-Test and ANOVA in Career-Technical Education Research

    Science.gov (United States)

    Rojewski, Jay W.; Lee, In Heok; Gemici, Sinan

    2012-01-01

    Use of t-tests and analysis of variance (ANOVA) procedures in published research from three scholarly journals in career and technical education (CTE) during a recent 5-year period was examined. Information on post hoc analyses, reporting of effect size, alpha adjustments to account for multiple tests, power, and examination of assumptions…

  7. An Opportunistic Routing for Data Forwarding Based on Vehicle Mobility Association in Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Leilei Wang

    2017-11-01

    Full Text Available Vehicular ad hoc networks (VANETs have emerged as a new powerful technology for data transmission between vehicles. Efficient data transmission accompanied with low data delay plays an important role in selecting the ideal data forwarding path in VANETs. This paper proposes a new opportunity routing protocol for data forwarding based on vehicle mobility association (OVMA. With assistance from the vehicle mobility association, data can be forwarded without passing through many extra intermediate nodes. Besides, each vehicle carries the only replica information to record its associated vehicle information, so the routing decision can adapt to the vehicle densities. Simulation results show that the OVMA protocol can extend the network lifetime, improve the performance of data delivery ratio, and reduce the data delay and routing overhead when compared to the other well-known routing protocols.

  8. Intelligent Security Auditing Based on Access Control of Devices in Ad Hoc Network

    Institute of Scientific and Technical Information of China (English)

    XU Guang-wei; SHI You-qun; ZHU Ming; WU Guo-wen; CAO Qi-ying

    2006-01-01

    Security in Ad Hoc network is an important issue under the opening circumstance of application service. Some protocols and models of security auditing have been proposed to ensure rationality of contracting strategy and operating regulation and used to identify abnormal operation. Model of security auditing based on access control of devices will be advanced to register sign of devices and property of event of access control and to audit those actions. In the end, the model is analyzed and simulated.

  9. Mobility Models for Next Generation Wireless Networks Ad Hoc, Vehicular and Mesh Networks

    CERN Document Server

    Santi, Paolo

    2012-01-01

    Mobility Models for Next Generation Wireless Networks: Ad Hoc, Vehicular and Mesh Networks provides the reader with an overview of mobility modelling, encompassing both theoretical and practical aspects related to the challenging mobility modelling task. It also: Provides up-to-date coverage of mobility models for next generation wireless networksOffers an in-depth discussion of the most representative mobility models for major next generation wireless network application scenarios, including WLAN/mesh networks, vehicular networks, wireless sensor networks, and

  10. Embedded Disposable Functionalized Electrochemical Biosensor with a 3D-Printed Flow Cell for Detection of Hepatic Oval Cells (HOCs

    Directory of Open Access Journals (Sweden)

    Samar Damiati

    2018-02-01

    Full Text Available Hepatic oval cells (HOCs are considered the progeny of the intrahepatic stem cells that are found in a small population in the liver after hepatocyte proliferation is inhibited. Due to their small number, isolation and capture of these cells constitute a challenging task for immunosensor technology. This work describes the development of a 3D-printed continuous flow system and exploits disposable screen-printed electrodes for the rapid detection of HOCs that over-express the OV6 marker on their membrane. Multiwall carbon nanotube (MWCNT electrodes have a chitosan film that serves as a scaffold for the immobilization of oval cell marker antibodies (anti-OV6-Ab, which enhance the sensitivity of the biomarker and makes the designed sensor specific for oval cells. The developed sensor can be easily embedded into the 3D-printed flow cell to allow cells to be exposed continuously to the functionalized surface. The continuous flow is intended to increase capture of most of the target cells in the specimen. Contact angle measurements were performed to characterize the nature and quality of the modified sensor surface, and electrochemical measurements (cyclic voltammetry (CV and square wave voltammetry (SWV were performed to confirm the efficiency and selectivity of the fabricated sensor to detect HOCs. The proposed method is valuable for capturing rare cells and could provide an effective tool for cancer diagnosis and detection.

  11. Embedded Disposable Functionalized Electrochemical Biosensor with a 3D-Printed Flow Cell for Detection of Hepatic Oval Cells (HOCs)

    Science.gov (United States)

    Peacock, Martin; Leonhardt, Stefan; Damiati, Laila; Baghdadi, Mohammed A.; Schuster, Bernhard

    2018-01-01

    Hepatic oval cells (HOCs) are considered the progeny of the intrahepatic stem cells that are found in a small population in the liver after hepatocyte proliferation is inhibited. Due to their small number, isolation and capture of these cells constitute a challenging task for immunosensor technology. This work describes the development of a 3D-printed continuous flow system and exploits disposable screen-printed electrodes for the rapid detection of HOCs that over-express the OV6 marker on their membrane. Multiwall carbon nanotube (MWCNT) electrodes have a chitosan film that serves as a scaffold for the immobilization of oval cell marker antibodies (anti-OV6-Ab), which enhance the sensitivity of the biomarker and makes the designed sensor specific for oval cells. The developed sensor can be easily embedded into the 3D-printed flow cell to allow cells to be exposed continuously to the functionalized surface. The continuous flow is intended to increase capture of most of the target cells in the specimen. Contact angle measurements were performed to characterize the nature and quality of the modified sensor surface, and electrochemical measurements (cyclic voltammetry (CV) and square wave voltammetry (SWV)) were performed to confirm the efficiency and selectivity of the fabricated sensor to detect HOCs. The proposed method is valuable for capturing rare cells and could provide an effective tool for cancer diagnosis and detection. PMID:29443890

  12. Embedded Disposable Functionalized Electrochemical Biosensor with a 3D-Printed Flow Cell for Detection of Hepatic Oval Cells (HOCs).

    Science.gov (United States)

    Damiati, Samar; Peacock, Martin; Leonhardt, Stefan; Damiati, Laila; Baghdadi, Mohammed A; Becker, Holger; Kodzius, Rimantas; Schuster, Bernhard

    2018-02-14

    Hepatic oval cells (HOCs) are considered the progeny of the intrahepatic stem cells that are found in a small population in the liver after hepatocyte proliferation is inhibited. Due to their small number, isolation and capture of these cells constitute a challenging task for immunosensor technology. This work describes the development of a 3D-printed continuous flow system and exploits disposable screen-printed electrodes for the rapid detection of HOCs that over-express the OV6 marker on their membrane. Multiwall carbon nanotube (MWCNT) electrodes have a chitosan film that serves as a scaffold for the immobilization of oval cell marker antibodies (anti-OV6-Ab), which enhance the sensitivity of the biomarker and makes the designed sensor specific for oval cells. The developed sensor can be easily embedded into the 3D-printed flow cell to allow cells to be exposed continuously to the functionalized surface. The continuous flow is intended to increase capture of most of the target cells in the specimen. Contact angle measurements were performed to characterize the nature and quality of the modified sensor surface, and electrochemical measurements (cyclic voltammetry (CV) and square wave voltammetry (SWV)) were performed to confirm the efficiency and selectivity of the fabricated sensor to detect HOCs. The proposed method is valuable for capturing rare cells and could provide an effective tool for cancer diagnosis and detection.

  13. Reducing Congestion in Obstructed Highways with Traffic Data Dissemination Using Ad hoc Vehicular Networks

    OpenAIRE

    Thomas D. Hewer; Maziar Nekovee; Peter V. Coveney

    2010-01-01

    Vehicle-to-vehicle communications can be used effectively for intelligent transport systems (ITSs) and location-aware services. The ability to disseminate information in an ad hoc fashion allows pertinent information to propagate faster through a network. In the realm of ITS, the ability to spread warning information faster and further is of great advantage to receivers. In this paper we propose and present a message-dissemination procedure that uses vehicular wireless protocols to influence...

  14. Energy-Efficient Cluster Based Routing Protocol in Mobile Ad Hoc Networks Using Network Coding

    OpenAIRE

    Srinivas Kanakala; Venugopal Reddy Ananthula; Prashanthi Vempaty

    2014-01-01

    In mobile ad hoc networks, all nodes are energy constrained. In such situations, it is important to reduce energy consumption. In this paper, we consider the issues of energy efficient communication in MANETs using network coding. Network coding is an effective method to improve the performance of wireless networks. COPE protocol implements network coding concept to reduce number of transmissions by mixing the packets at intermediate nodes. We incorporate COPE into cluster based routing proto...

  15. EFECTO DE LOS OBSTÁCULOS TIPO POLIMERO RESINA EN RENDIMIENTO DE REDES TCP/IP/IEEE 802.11g MODO AD-HOC

    OpenAIRE

    Márquez Barriobero, David

    2011-01-01

    La investigación tiene como objetivo primordial el desarrollo de un modelo matemático para evaluar el efecto de los obstáculos de tipo polímero resina en el rendimiento de redes TCP/IP/IEEE 802.11g modo ad-hoc; esto con el propósito de establecer la relación existente entre el diámetro de los obstáculos de tipo polímero resina y el rendimiento de una red inalámbrica en modo ad-hoc, al transmitir datos vía protocolo FTP. El tipo de investigación es explicativa con un diseño experimental. Los t...

  16. Post hoc analysis of Japanese patients from the placebo-controlled PREVAIL trial of enzalutamide in patients with chemotherapy-naive, metastatic castration-resistant prostate cancer-updated results.

    Science.gov (United States)

    Kimura, Go; Ueda, Takeshi

    2017-03-01

    A post hoc analysis of interim results from PREVAIL, a Phase III, double-blind, placebo-controlled trial of men with metastatic castration-resistant prostate cancer, demonstrated that the treatment effects, safety and pharmacokinetics of enzalutamide in Japanese patients were generally consistent with those of the overall population. A recent longer term analysis of PREVAIL demonstrated continued benefit of enzalutamide treatment over placebo. Here, we report results from a post hoc analysis of Japanese patients enrolled in PREVAIL at the prespecified number of deaths for the final analysis. In Japanese patients, enzalutamide reduced the risk of death by 35% (hazard ratio, 0.65; 95% confidence interval, 0.28-1.51) and the risk of investigator-assessed radiographic progression or death by 60% (hazard ratio, 0.40; 95% confidence interval, 0.18-0.90). These results show that treatment effects and safety in Japanese patients in the final analysis of PREVAIL continued to be generally consistent with those of the overall population. © The Author 2016. Published by Oxford University Press.

  17. Pseudo-Coherence-Based MVDR Beamformer for Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2015-01-01

    Speech enhancement with distributed arrays has been met with various methods. On the one hand, data independent methods require information about the position of sensors, so they are not suitable for dynamic geometries. On the other hand, Wiener-based methods cannot assure a distortionless output....... This paper proposes minimum variance distortionless response filtering based on multichannel pseudo-coherence for speech enhancement with ad hoc microphone arrays. This method requires neither position information nor control of the trade-off used in the distortion weighted methods. Furthermore, certain...

  18. A time-based admission control mechanism for IEEE 802.11 ad Hoc networks

    OpenAIRE

    Costa, Luís Henrique M. K.; Cerveira, Carlos Rodrigo

    2006-01-01

    This paper presents a time-based admission control mechanism (TAC) for IEEE 802.11 ad hoc networks. The proposed mechanism was adapted to the QoS AODV routing protocol, which takes the quality of service requirements of the data flow into account in the route discovery process. TAC-AODV estimates the idle time of the physical medium based on the frames listened. The incoming traffic is admitted according to the offered load as well as the intra-flow interference, calculated based on the numbe...

  19. Smart vehicle monitoring and assistance using cloud computing in vehicular Ad Hoc networks

    Directory of Open Access Journals (Sweden)

    Yash Agarwal

    2018-03-01

    Full Text Available The increasing number of on road vehicles has become a major cause for congestion, accidents and pollution. Intelligent Transportation Systems (ITS might be the key to achieve solutions that help in reducing these problems significantly. The connected vehicular networks stream is a rapidly growing field for research and development of various real-time applications. In this paper, novel techniques have been proposed to serve the speed based lane changing, collision avoidance and time of arrival (TOA based localization in Vehicular Ad Hoc Networks (VANETs. As GPS requires clear line-of-sight for accurate services of positioning and localization applications, we designed a Time of Arrival (ToA based algorithm for areas where strong GPS signals are unavailable. Collision avoidance using automatic braking and camera-based surveillance are a few other applications that we addressed. The feasibility and the viability of the algorithms were demonstrated through simulations in Simulation of Urban Mobility (SUMO and Network Simulator-2 (NS-2. We prototyped a working hardware and tested it on actual vehicles to assess the effectiveness of the proposed system. We designed a mobile app interface for the on-board unit for smart, efficient and remote traffic monitoring. The integrated VANET Cloud Computing architecture acts as the platform for the proposed applications.

  20. Definition of simulated driving tests for the evaluation of drivers' reactions and responses.

    Science.gov (United States)

    Bartolozzi, Riccardo; Frendo, Francesco

    2014-01-01

    This article aims at identifying the most significant measures in 2 perception-response (PR) tests performed at a driving simulator: a braking test and a lateral skid test, which were developed in this work. Forty-eight subjects (26 females and 22 males) with a mean age of 24.9 ± 3.0 years were enrolled for this study. They were asked to perform a drive on the driving simulator at the University of Pisa (Italy) following a specific test protocol, including 8-10 braking tests and 8-10 lateral skid tests. Driver input signals and vehicle model signals were recorded during the drives and analyzed to extract measures such as the reaction time, first response time, etc. Following a statistical procedure (based on analysis of variance [ANOVA] and post hoc tests), all test measures (3 for the braking test and 8 for the lateral skid test) were analyzed in terms of statistically significant differences among different drivers. The presented procedure allows evaluation of the capability of a given test to distinguish among different drivers. In the braking test, the reaction time showed a high dispersion among single drivers, leading to just 4.8 percent of statistically significant driver pairs (using the Games-Howell post hoc test), whereas the pedal transition time scored 31.9 percent. In the lateral skid test, 28.5 percent of the 2 × 2 comparisons showed significantly different reaction times, 19.5 percent had different response times, 35.2 percent had a different second peak of the steering wheel signal, and 33 percent showed different values of the integral of the steering wheel signal. For the braking test, which has been widely employed in similar forms in the literature, it was shown how the reaction time, with respect to the pedal transition time, can have a higher dispersion due to the influence of external factors. For the lateral skid test, the following measures were identified as the most significant for application studies: the reaction time for the reaction

  1. A Mobility-Aware Link Enhancement Mechanism for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Kai-Wen Hu

    2008-04-01

    Full Text Available With the growth up of internet in mobile commerce, researchers have reproduced various mobile applications that vary from entertainment and commercial services to diagnostic and safety tools. Mobility management has widely been recognized as one of the most challenging problems for seamless access to wireless networks. In this paper, a novel link enhancement mechanism is proposed to deal with mobility management problem in vehicular ad hoc networks. Two machine learning techniques, namely, particle swarm optimization and fuzzy logic systems, are incorporated into the proposed schemes to enhance the accuracy of prediction of link break and congestion occurrence. The experimental results verify the effectiveness and feasibility of the proposed schemes.

  2. A Mobility-Aware Link Enhancement Mechanism for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Huang Chenn-Jung

    2008-01-01

    Full Text Available Abstract With the growth up of internet in mobile commerce, researchers have reproduced various mobile applications that vary from entertainment and commercial services to diagnostic and safety tools. Mobility management has widely been recognized as one of the most challenging problems for seamless access to wireless networks. In this paper, a novel link enhancement mechanism is proposed to deal with mobility management problem in vehicular ad hoc networks. Two machine learning techniques, namely, particle swarm optimization and fuzzy logic systems, are incorporated into the proposed schemes to enhance the accuracy of prediction of link break and congestion occurrence. The experimental results verify the effectiveness and feasibility of the proposed schemes.

  3. Time-Optimal Real-Time Test Case Generation using UPPAAL

    DEFF Research Database (Denmark)

    Hessel, Anders; Larsen, Kim Guldstrand; Nielsen, Brian

    2004-01-01

    Testing is the primary software validation technique used by industry today, but remains ad hoc, error prone, and very expensive. A promising improvement is to automatically generate test cases from formal models of the system under test. We demonstrate how to automatically generate real...... test purposes or generated automatically from various coverage criteria of the model.......-time conformance test cases from timed automata specifications. Specifically we demonstrate how to fficiently generate real-time test cases with optimal execution time i.e test cases that are the fastest possible to execute. Our technique allows time optimal test cases to be generated using manually formulated...

  4. ADNP-CSMA Random Multiple Access protocol application with the function of monitoring in Ad Hoc network

    Directory of Open Access Journals (Sweden)

    Zhan Gang

    2016-01-01

    Full Text Available In Ad Hoc networks,the net work of mobile nodes exchange information with their wireless transceiver equipment,the network throughput is in increased,compared to other such multiple hops network.Moreover along with the rapid development of modern information,communication business also will be increase.However,the access and adaptive of previous CSMA protocol are insufficient.According to these properties,this paper presents a kind of adaptive dual clock with monitoring function P-CSMA random multiple access protocol(ADNP-CSMA,and discusses two kinds of P-CSMA.ACK with monitoring function is introduced to maintain the stability of the whole system,and the introduction of dual clock mechanism reduces the channel of idle period.It calculate the system throughput expression through the method of average period,and the simulation results show that the system is constant in the case of high load throughput.

  5. Reputation-Based Internet Protocol Security: A Multilayer Security Framework for Mobile Ad Hoc Networks

    Science.gov (United States)

    2010-09-01

    motivated research in behavior grading systems [56]. Peer-to-peer eCommerce appli- cations such as eBay, Amazon, uBid, and Yahoo have performed research that...Security in Mobile Ad Hoc Networks”. IEEE Security & Privacy , 72–75, 2008. 15. Chakeres, ID and EM Belding-Royer. “AODV Routing Protocol Implementa...Detection System”. Proceedings of IEEE Computer Society Symposium on Research in Security and Privacy , 240–250. 1992. 21. Devore, J.L. and N.R. Farnum

  6. Energy-efficient algorithm for broadcasting in ad hoc wireless sensor networks.

    Science.gov (United States)

    Xiong, Naixue; Huang, Xingbo; Cheng, Hongju; Wan, Zheng

    2013-04-12

    Broadcasting is a common and basic operation used to support various network protocols in wireless networks. To achieve energy-efficient broadcasting is especially important for ad hoc wireless sensor networks because sensors are generally powered by batteries with limited lifetimes. Energy consumption for broadcast operations can be reduced by minimizing the number of relay nodes based on the observation that data transmission processes consume more energy than data reception processes in the sensor nodes, and how to improve the network lifetime is always an interesting issue in sensor network research. The minimum-energy broadcast problem is then equivalent to the problem of finding the minimum Connected Dominating Set (CDS) for a connected graph that is proved NP-complete. In this paper, we introduce an Efficient Minimum CDS algorithm (EMCDS) with help of a proposed ordered sequence list. EMCDS does not concern itself with node energy and broadcast operations might fail if relay nodes are out of energy. Next we have proposed a Minimum Energy-consumption Broadcast Scheme (MEBS) with a modified version of EMCDS, and aimed at providing an efficient scheduling scheme with maximized network lifetime. The simulation results show that the proposed EMCDS algorithm can find smaller CDS compared with related works, and the MEBS can help to increase the network lifetime by efficiently balancing energy among nodes in the networks.

  7. An Efficient and QoS Supported Multichannel MAC Protocol for Vehicular Ad Hoc Networks.

    Science.gov (United States)

    Song, Caixia; Tan, Guozhen; Yu, Chao

    2017-10-09

    Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety (transport efficiency and infotainment) applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. Different types of applications require different levels Quality-of-Service (QoS) support. Recently, transport efficiency and infotainment applications (e.g., electronic map download and Internet access) have received more and more attention, and this kind of applications is expected to become a big market driver in a near future. In this paper, we propose an Efficient and QoS supported Multichannel Medium Access Control (EQM-MAC) protocol for VANETs in a highway environment. The EQM-MAC protocol utilizes the service channel resources for non-safety message transmissions during the whole synchronization interval, and it dynamically adjusts minimum contention window size for different non-safety services according to the traffic conditions. Theoretical model analysis and extensive simulation results show that the EQM-MAC protocol can support QoS services, while ensuring the high saturation throughput and low transmission delay for non-safety applications.

  8. An Efficient and QoS Supported Multichannel MAC Protocol for Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Caixia Song

    2017-10-01

    Full Text Available Vehicular Ad Hoc Networks (VANETs employ multichannel to provide a variety of safety and non-safety (transport efficiency and infotainment applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. Different types of applications require different levels Quality-of-Service (QoS support. Recently, transport efficiency and infotainment applications (e.g., electronic map download and Internet access have received more and more attention, and this kind of applications is expected to become a big market driver in a near future. In this paper, we propose an Efficient and QoS supported Multichannel Medium Access Control (EQM-MAC protocol for VANETs in a highway environment. The EQM-MAC protocol utilizes the service channel resources for non-safety message transmissions during the whole synchronization interval, and it dynamically adjusts minimum contention window size for different non-safety services according to the traffic conditions. Theoretical model analysis and extensive simulation results show that the EQM-MAC protocol can support QoS services, while ensuring the high saturation throughput and low transmission delay for non-safety applications.

  9. Data delivery method based on neighbor nodes' information in a mobile ad hoc network.

    Science.gov (United States)

    Kashihara, Shigeru; Hayashi, Takuma; Taenaka, Yuzo; Okuda, Takeshi; Yamaguchi, Suguru

    2014-01-01

    This paper proposes a data delivery method based on neighbor nodes' information to achieve reliable communication in a mobile ad hoc network (MANET). In a MANET, it is difficult to deliver data reliably due to instabilities in network topology and wireless network condition which result from node movement. To overcome such unstable communication, opportunistic routing and network coding schemes have lately attracted considerable attention. Although an existing method that employs such schemes, MAC-independent opportunistic routing and encoding (MORE), Chachulski et al. (2007), improves the efficiency of data delivery in an unstable wireless mesh network, it does not address node movement. To efficiently deliver data in a MANET, the method proposed in this paper thus first employs the same opportunistic routing and network coding used in MORE and also uses the location information and transmission probabilities of neighbor nodes to adapt to changeable network topology and wireless network condition. The simulation experiments showed that the proposed method can achieve efficient data delivery with low network load when the movement speed is relatively slow.

  10. Data Delivery Method Based on Neighbor Nodes’ Information in a Mobile Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Shigeru Kashihara

    2014-01-01

    Full Text Available This paper proposes a data delivery method based on neighbor nodes’ information to achieve reliable communication in a mobile ad hoc network (MANET. In a MANET, it is difficult to deliver data reliably due to instabilities in network topology and wireless network condition which result from node movement. To overcome such unstable communication, opportunistic routing and network coding schemes have lately attracted considerable attention. Although an existing method that employs such schemes, MAC-independent opportunistic routing and encoding (MORE, Chachulski et al. (2007, improves the efficiency of data delivery in an unstable wireless mesh network, it does not address node movement. To efficiently deliver data in a MANET, the method proposed in this paper thus first employs the same opportunistic routing and network coding used in MORE and also uses the location information and transmission probabilities of neighbor nodes to adapt to changeable network topology and wireless network condition. The simulation experiments showed that the proposed method can achieve efficient data delivery with low network load when the movement speed is relatively slow.

  11. Selective Route Based on SNR with Cross-Layer Scheme in Wireless Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Istikmal

    2017-01-01

    Full Text Available In this study, we developed network and throughput formulation models and proposed new method of the routing protocol algorithm with a cross-layer scheme based on signal-to-noise ratio (SNR. This method is an enhancement of routing protocol ad hoc on-demand distance vector (AODV. This proposed scheme uses selective route based on the SNR threshold in the reverse route mechanism. We developed AODV SNR-selective route (AODV SNR-SR for a mechanism better than AODV SNR, that is, the routing protocol that used average or sum of path SNR, and also better than AODV which is hop-count-based. We also used selective reverse route based on SNR mechanism, replacing the earlier method to avoid routing overhead. The simulation results show that AODV SNR-SR outperforms AODV SNR and AODV in terms of throughput, end-to-end delay, and routing overhead. This proposed method is expected to support Device-to-Device (D2D communications that are concerned with the quality of the channel awareness in the development of the future Fifth Generation (5G.

  12. Energy-Efficient Cluster Based Routing Protocol in Mobile Ad Hoc Networks Using Network Coding

    Directory of Open Access Journals (Sweden)

    Srinivas Kanakala

    2014-01-01

    Full Text Available In mobile ad hoc networks, all nodes are energy constrained. In such situations, it is important to reduce energy consumption. In this paper, we consider the issues of energy efficient communication in MANETs using network coding. Network coding is an effective method to improve the performance of wireless networks. COPE protocol implements network coding concept to reduce number of transmissions by mixing the packets at intermediate nodes. We incorporate COPE into cluster based routing protocol to further reduce the energy consumption. The proposed energy-efficient coding-aware cluster based routing protocol (ECCRP scheme applies network coding at cluster heads to reduce number of transmissions. We also modify the queue management procedure of COPE protocol to further improve coding opportunities. We also use an energy efficient scheme while selecting the cluster head. It helps to increase the life time of the network. We evaluate the performance of proposed energy efficient cluster based protocol using simulation. Simulation results show that the proposed ECCRP algorithm reduces energy consumption and increases life time of the network.

  13. Older people experiencing homelessness show marked impairment on tests of frontal lobe function.

    Science.gov (United States)

    Rogoz, Astrid; Burke, David

    2016-03-01

    Reported rates of mild and moderate cognitive impairment in older people experiencing homelessness range from 5-80%. The objective of this study was to determine the prevalence and characteristics of cognitive impairment in older people experiencing homelessness in the inner city of Sydney, Australia. Men and women experiencing homelessness aged 45 years and over in the inner city were screened for cognitive impairment. Participants who scored 26 or below on the mini-mental state examination and/or were impaired on any one of the clock-drawing test, the verbal fluency test and the trail-making test, part B were then assessed with a semi-structured interview, including the 21-item Depression Anxiety Stress Scale and the 12-item General Health Questionnaire. Screening of 144 men and 27 women aged between 45 years and 93 years identified cognitive impairment in 78%. Subsequently, high rates of mental and physical illness were identified, and 75% of subjects who were cognitively impaired performed poorly on frontal lobe tests. The trail-making test, part B was the most sensitive measure of frontal function. This study demonstrated that a large majority of older people experiencing homelessness, in the inner city of a high-income country, showed impairment on tests of frontal lobe function, a finding that could have significant implications for any medical or psychosocial intervention. Copyright © 2015 John Wiley & Sons, Ltd.

  14. Nausea and Vomiting following Balanced Xenon Anesthesia Compared to Sevoflurane: A Post-Hoc Explorative Analysis of a Randomized Controlled Trial.

    Directory of Open Access Journals (Sweden)

    Astrid V Fahlenkamp

    Full Text Available Like other inhalational anesthetics xenon seems to be associated with post-operative nausea and vomiting (PONV. We assessed nausea incidence following balanced xenon anesthesia compared to sevoflurane, and dexamethasone for its prophylaxis in a randomized controlled trial with post-hoc explorative analysis.220 subjects with elevated PONV risk (Apfel score ≥2 undergoing elective abdominal surgery were randomized to receive xenon or sevoflurane anesthesia and dexamethasone or placebo after written informed consent. 93 subjects in the xenon group and 94 subjects in the sevoflurane group completed the trial. General anesthesia was maintained with 60% xenon or 2.0% sevoflurane. Dexamethasone 4mg or placebo was administered in the first hour. Subjects were analyzed for nausea and vomiting in predefined intervals during a 24h post-anesthesia follow-up.Logistic regression, controlled for dexamethasone and anesthesia/dexamethasone interaction, showed a significant risk to develop nausea following xenon anesthesia (OR 2.30, 95% CI 1.02-5.19, p = 0.044. Early-onset nausea incidence was 46% after xenon and 35% after sevoflurane anesthesia (p = 0.138. After xenon, nausea occurred significantly earlier (p = 0.014, was more frequent and rated worse in the beginning. Dexamethasone did not markedly reduce nausea occurrence in both groups. Late-onset nausea showed no considerable difference between the groups.In our study setting, xenon anesthesia was associated with an elevated risk to develop nausea in sensitive subjects. Dexamethasone 4mg was not effective preventing nausea in our study. Group size or dosage might have been too small, and change of statistical analysis parameters in the post-hoc evaluation might have further contributed to a limitation of our results. Further trials will be needed to address prophylaxis of xenon-induced nausea.EU Clinical Trials EudraCT-2008-004132-20 ClinicalTrials.gov NCT00793663.

  15. A COMPREHENSIVE SURVEY ON DETECTING BLACK HOLE ATTACK IN MOBILE AD-HOC NETWORK (MANET

    Directory of Open Access Journals (Sweden)

    Pascal Maniriho

    2018-01-01

    Full Text Available The infrastructure-less nature and mobility of nodes in mobile ad-hoc network (MANET make it to be very susceptible to various attacks. Besides, owing to its flexibility and simplicity, there is no predefined time or permission set for nodes to leave or join the network and each node can act as a client or server.  Nevertheless, securing communication between nodes has become a challenging problem than in other types of network. Attacks in MANET range into different categories. Black hole attack is one of the attacks that has been addressed by many researchers in the recent years. It does occur when a harmful mobile node called black hole becomes a part of the network and tries to use its malicious behaviors by sending fake route reply packets (RREP for any received route request packets (RREQ. When these faked packets arrive to the source node, it does reply to them by sending data packet via the established route. Once the packets are received by the black hole, it drops them before reaching the destination.  Hence, preventing the source node from reaching the intended destination. In this paper, we present an overview of a wide range of techniques suggested in the literature for detecting and preventing black hole attacks in mobile ad hoc network. Additionally, the effect of each approach on the network performance is also presented.

  16. Robotic disaster recovery efforts with ad-hoc deployable cloud computing

    Science.gov (United States)

    Straub, Jeremy; Marsh, Ronald; Mohammad, Atif F.

    2013-06-01

    Autonomous operations of search and rescue (SaR) robots is an ill posed problem, which is complexified by the dynamic disaster recovery environment. In a typical SaR response scenario, responder robots will require different levels of processing capabilities during various parts of the response effort and will need to utilize multiple algorithms. Placing these capabilities onboard the robot is a mediocre solution that precludes algorithm specific performance optimization and results in mediocre performance. Architecture for an ad-hoc, deployable cloud environment suitable for use in a disaster response scenario is presented. Under this model, each service provider is optimized for the task and maintains a database of situation-relevant information. This service-oriented architecture (SOA 3.0) compliant framework also serves as an example of the efficient use of SOA 3.0 in an actual cloud application.

  17. Making friends on the fly advances in ad hoc teamwork

    CERN Document Server

    Barrett, Samuel

    2015-01-01

    This book is devoted to the encounter and interaction of agents such as robots with other agents and describes how they cooperate with their previously unknown teammates, forming an Ad Hoc team. It presents a new algorithm, PLASTIC, that allows agents to quickly adapt to new teammates by reusing knowledge learned from previous teammates.  PLASTIC is instantiated in both a model-based approach, PLASTIC-Model, and a policy-based approach, PLASTIC-Policy.  In addition to reusing knowledge learned from previous teammates, PLASTIC also allows users to provide expert-knowledge and can use transfer learning (such as the new TwoStageTransfer algorithm) to quickly create models of new teammates when it has some information about its new teammates. The effectiveness of the algorithm is demonstrated on three domains, ranging from multi-armed bandits to simulated robot soccer games.

  18. Energy-Aware Multipath Routing Scheme Based on Particle Swarm Optimization in Mobile Ad Hoc Networks.

    Science.gov (United States)

    Robinson, Y Harold; Rajaram, M

    2015-01-01

    Mobile ad hoc network (MANET) is a collection of autonomous mobile nodes forming an ad hoc network without fixed infrastructure. Dynamic topology property of MANET may degrade the performance of the network. However, multipath selection is a great challenging task to improve the network lifetime. We proposed an energy-aware multipath routing scheme based on particle swarm optimization (EMPSO) that uses continuous time recurrent neural network (CTRNN) to solve optimization problems. CTRNN finds the optimal loop-free paths to solve link disjoint paths in a MANET. The CTRNN is used as an optimum path selection technique that produces a set of optimal paths between source and destination. In CTRNN, particle swarm optimization (PSO) method is primly used for training the RNN. The proposed scheme uses the reliability measures such as transmission cost, energy factor, and the optimal traffic ratio between source and destination to increase routing performance. In this scheme, optimal loop-free paths can be found using PSO to seek better link quality nodes in route discovery phase. PSO optimizes a problem by iteratively trying to get a better solution with regard to a measure of quality. The proposed scheme discovers multiple loop-free paths by using PSO technique.

  19. Link reliability based hybrid routing for tactical mobile ad hoc network

    Institute of Scientific and Technical Information of China (English)

    Xie Xiaochuan; Wei Gang; Wu Keping; Wang Gang; Jia Shilou

    2008-01-01

    Tactical mobile ad hoc network (MANET) is a collection of mobile nodes forming a temporary network,without the aid of pre-established network infrastructure. The routing protocol has a crucial impact on the networkperformance in battlefields. Link reliability based hybrid routing (LRHR) is proposed, which is a novel hybrid routing protocol, for tactical MANET. Contrary to the traditional single path routing strategy, multiple paths are established between a pair of source-destination nodes. In the hybrid routing strategy, the rate of topological change provides a natural mechanism for switching dynamically between table-driven and on-demand routing. The simulation results indicate that the performances of the protocol in packet delivery ratio, routing overhead, and average end-to-end delay are better than the conventional routing protocol.

  20. The Survival Processing Effect with Intentional Learning of Ad Hoc Categories

    Directory of Open Access Journals (Sweden)

    Anastasiya Savchenko

    2014-04-01

    Full Text Available Previous studies have shown that memory is adapted to remember information when it is processed in a survival context. This study investigates how procedural changes in Marinho (2012 study might have led to her failure to replicate the survival mnemonic advantage. In two between-subjects design experiments, participants were instructed to learn words from ad hoc categories and to rate their relevance to a survival or a control scenario. No survival advantage was obtained in either experiment. The Adjusted Ratio of Clustering (ARC scores revealed that including the category labels made the participants rely more on the category structure of the list. Various procedural aspects of the conducted experiments are discussed as possible reasons underlying the absence of the survival effect.

  1. A Rate-Adaptive MAC Protocol Based on TCP throughput for Ad Hoc Networks in Fading Channels

    Directory of Open Access Journals (Sweden)

    Shoko Uchida

    2008-10-01

    Full Text Available Wireless technology is becoming a leading option for future Internet access. Transmission Control Protocol (TCP is one of the protocols designed on the basis of the transmission characteristics in wired networks. It is known that the TCP performance deteriorates drastically under a wireless communication environment. On the other hand, many wireless networking standards such as IEEE 802.11a, 802.11b, and 802.11g have multirate capability. Therefore, adaptive rate control methods have been proposed for ad hoc networks. However, almost methods require the modification of the request to send (RTS and clear to send (CTS packets. Therefore, the conventional methods are not compatible with the standardized system. In this paper, we propose adaptive rate control mechanisms for ad hoc networks. Our mechanisms are based on the RTS/CTS mechanisms. However, no modifications to the RTS and CTS packets are required in the proposed method. Therefore, our proposed method can attempt to satisfy the conventional IEEE 802.11 standards. Moreover, an adequate transmission rate is selected based on an estimated TCP throughput performance. From simulation results, it is observed that the proposed method can improve the throughput performance without any modification of packet structures.

  2. Dating currency crises with ad hoc and extreme value-based thresholds : East Asia 1970-2002 [dating currency crises

    NARCIS (Netherlands)

    Lestano, L; Jacobs, Jan P. A. M.

    2007-01-01

    Generally a currency crisis is defined to occur if an index of currency pressure exceeds a threshold. This paper compares currency crisis dating methods. For two definitions of currency pressure we contrast ad hoc and extreme value-based thresholds. We illustrate the methods with data of six East

  3. Quality assurance in the nuclear test program

    International Nuclear Information System (INIS)

    Shearer, J.N.

    1979-01-01

    In February 1979 Test Program laid the ground work for a new quality assurance structure. The new approach was based on the findings and recommendations of the Ad Hoc QA Program Review panel, which are summarized in this report. The new structure places the responsibility for quality assurance in the hands of the line organizations, both in the programmatic and functional elements of the LLL matrix

  4. OPNET Modeler Simulation Testing of the New Model Used to Cooperation Between QoS and Security Mechanisms

    Directory of Open Access Journals (Sweden)

    Jan Papaj

    2012-01-01

    Full Text Available In this article the performance analysis of the new model, used to integration between QoS and Security, is introduced. OPNET modeler simulation testing of the new model with comparation with the standard model is presented. This new model enables the process of cooperation between QoS and Security in MANET. The introduction how the model is implemented to the simulation OPNET modeler is also showed. Model provides possibilities to integration and cooperation of QoS and security by the cross layer design (CLD with modified security service vector (SSV. An overview of the simulation tested of the new model, comparative study in mobile ad-hoc networks, describe requirements and directions for adapted solutions are presented. Main idea of the testing is to show how QoS and Security related services could be provided simultaneously with using minimal interfering with each service.

  5. Information Sharing Mechanism among Mobile Agents In Ad-hoc Network Environment and Its Applications

    Directory of Open Access Journals (Sweden)

    Kunio Umetsuji

    2004-12-01

    Full Text Available Mobile agents are programs that can move from one site to another in a network with their data and states. Mobile agents are expected to be an essential tool in pervasive computing. In multi platform environment, it is important to communicate with mobile agents only using their universal or logical name not using their physical locations. More, in an ad-hoc network environment, an agent can migrate autonomously and communicate with other agents on demand. It is difficult that mobile agent grasps the position information on other agents correctly each other, because mobile agent processes a task while moving a network successively. In order to realize on-demand mutual communication among mobile agents without any centralized servers, we propose a new information sharing mechanism within mobile agents. In this paper, we present a new information sharing mechanism within mobile agents. The method is a complete peer based and requires no agent servers to manage mobile agent locations. Therefore, a mobile agent can get another mobile agent, communicate with it and shares information stored in the agent without any knowledge of the location of the target mobile agent. The basic idea of the mechanism is an introduction of Agent Ring, Agent Chain and Shadow Agent. With this mechanism, each agent can communicate with other agents in a server-less environment, which is suitable for ad-hoc agent network and an agent system can manage agents search and communications efficiently.

  6. TRIBUNALES PENALES INTERNACIONALES AD HOC DEL POST-GUERRA FRÍA: CAMBIANDO PARADIGMAS EN EL TRATAMIENTO DE CUESTIONES DE GÉNERO

    Directory of Open Access Journals (Sweden)

    Camila Soares Lippi

    2011-12-01

    Full Text Available Analizaremos como la jurisprudencia de los Tribunales Penales Internacionales ad hoc del post-Guerra Fría representa un cambio de paradigmas en cuestiones de género en el Derecho Penal Internacional y en el Derecho Internacional Humanitario. Para eso, partimos del concepto de género, o sea, las construcciones sociales cuanto a los roles masculino y femenino, como categoría central de análisis. Analizamos, primeramente, el post-Segunda Guerra Mundial. Ese momento histórico, ejemplificado por los Tribunales de Núremberg y de Tokio y por los Convenios de Ginebra de 1949. Después analizase los Tribunales Penales Internacionales ad hoc del post-Guerra Fría. Finalmente, analizamos la definición de género en el Estatuto de Roma, que instituye el Tribunal Penal Internacional.

  7. A FSA Model for Performance Evaluation over Mobile Ad Hoc Networks with Low Traffic Volume

    Directory of Open Access Journals (Sweden)

    Heng LUO

    2014-07-01

    Full Text Available A Mobile Ad hoc network (MANET, which is composed of nodes that are able to move arbitrarily, differs from a direct connection network in the way that it is multi-hopping and self- organizing and thus able to operate without the help of prefixed infrastructures. However, problems such as unfavorable wireless links and dynamic topology are challenging, resulting in the proposal of a collection of routing protocols for MANETs. Nevertheless the performance of protocols may deteriorate dramatically as deployment scenario changes due to the application dependent philosophy behind algorithms. In this paper, the performance evaluation problem for MANETs and is explored and a novel performance ranking model, termed FSA, is proposed. For simplicity but without loss of generality, the performance of two routing protocols DSDV and DSR are studies. The FSA is able to rank the performance of DSDV and DSR depending on the average value and standard deviation results. Extensive simulations show that an overall 20.74 %, at most, gain may be achieved based on the FSA model.

  8. Cooperative ad hoc networks for energy and delay efficient content distribution with fast channel variations

    KAUST Repository

    Atat, Rachad

    2012-11-20

    Cooperative ad hoc networks for the efficient distribution of content of common interest are studied in the case of fast channel variations. Mobiles are grouped into cooperative clusters for the purpose of receiving the content with optimized energy efficiency. Data are sent to mobile terminals on a long range (LR) link, and then, the terminals exchange the content by using an appropriate short range wireless technology. When channel state information is available for the LR links, unicasting is used on the LR. When accurate channel state information is not available, threshold-based multicasting is implemented on the LR. Energy minimization is formulated as an optimization problem for each scenario, and the optimal solutions are determined in closed form in scenarios with fast channel variations. Results show significant energy savings in the proposed schemes compared with the noncooperative case and other previous related work. Furthermore, the energy minimizing solutions are shown to lead to reduced delay in the content distribution process. Practical implementation aspects of the proposed methods are also discussed. © 2012 John Wiley & Sons, Ltd.

  9. Cooperative ad hoc networks for energy and delay efficient content distribution with fast channel variations

    KAUST Repository

    Atat, Rachad; Yaacoub, Elias E.; Alouini, Mohamed-Slim; Abu-Dayya, Adnan A.

    2012-01-01

    Cooperative ad hoc networks for the efficient distribution of content of common interest are studied in the case of fast channel variations. Mobiles are grouped into cooperative clusters for the purpose of receiving the content with optimized energy efficiency. Data are sent to mobile terminals on a long range (LR) link, and then, the terminals exchange the content by using an appropriate short range wireless technology. When channel state information is available for the LR links, unicasting is used on the LR. When accurate channel state information is not available, threshold-based multicasting is implemented on the LR. Energy minimization is formulated as an optimization problem for each scenario, and the optimal solutions are determined in closed form in scenarios with fast channel variations. Results show significant energy savings in the proposed schemes compared with the noncooperative case and other previous related work. Furthermore, the energy minimizing solutions are shown to lead to reduced delay in the content distribution process. Practical implementation aspects of the proposed methods are also discussed. © 2012 John Wiley & Sons, Ltd.

  10. Monitoring and classifying animal behavior using ZigBee-based mobile ad hoc wireless sensor networks and artificial neural networks

    DEFF Research Database (Denmark)

    S. Nadimi, Esmaeil; Nyholm Jørgensen, Rasmus; Blanes-Vidal, Victoria

    2012-01-01

    Animal welfare is an issue of great importance in modern food production systems. Because animal behavior provides reliable information about animal health and welfare, recent research has aimed at designing monitoring systems capable of measuring behavioral parameters and transforming them...... into their corresponding behavioral modes. However, network unreliability and high-energy consumption have limited the applicability of those systems. In this study, a 2.4-GHz ZigBee-based mobile ad hoc wireless sensor network (MANET) that is able to overcome those problems is presented. The designed MANET showed high...... communication reliability, low energy consumption and low packet loss rate (14.8%) due to the deployment of modern communication protocols (e.g. multi-hop communication and handshaking protocol). The measured behavioral parameters were transformed into the corresponding behavioral modes using a multilayer...

  11. Probabilistic Modelling of Information Propagation in Wireless Mobile Ad-Hoc Network

    DEFF Research Database (Denmark)

    Schiøler, Henrik; Hansen, Martin Bøgsted; Schwefel, Hans-Peter

    2005-01-01

    In this paper the dynamics of broadcasting wireless ad-hoc networks is studied through probabilistic modelling. A randomized transmission discipline is assumed in accordance with existing MAC definitions such as WLAN with Decentralized Coordination or IEEE-802.15.4. Message reception is assumed...... to be governed by node power-down policies and is equivalently assumed to be randomized. Altogether randomization facilitates a probabilistic model in the shape of an integro-differential equation governing the propagation of information, where brownian node mobility may be accounted for by including an extra...... diffusion term. The established model is analyzed for transient behaviour and a travelling wave solution facilitates expressions for propagation speed as well as parametrized analysis of network reliability and node power consumption. Applications of the developed models for node localization and network...

  12. Outcome when adrenaline (epinephrine) was actually given vs. not given - post hoc analysis of a randomized clinical trial.

    Science.gov (United States)

    Olasveengen, Theresa M; Wik, Lars; Sunde, Kjetil; Steen, Petter A

    2012-03-01

    IV line insertion and drugs did not affect long-term survival in an out-of-hospital cardiac arrest (OHCA) randomized clinical trial (RCT). In a previous large registry study adrenaline was negatively associated with survival from OHCA. The present post hoc analysis on the RCT data compares outcomes for patients actually receiving adrenaline to those not receiving adrenaline. Patients from a RCT performed May 2003 to April 2008 were included. Three patients from the original intention-to-treat analysis were excluded due to insufficient documentation of adrenaline administration. Quality of cardiopulmonary resuscitation (CPR) and clinical outcomes were compared. Clinical characteristics were similar and CPR quality comparable and within guideline recommendations for 367 patients receiving adrenaline and 481 patients not receiving adrenaline. Odds ratio (OR) for being admitted to hospital, being discharged from hospital and surviving with favourable neurological outcome for the adrenaline vs. no-adrenaline group was 2.5 (CI 1.9, 3.4), 0.5 (CI 0.3, 0.8) and 0.4 (CI 0.2, 0.7), respectively. Ventricular fibrillation, response interval, witnessed arrest, gender, age and endotracheal intubation were confounders in multivariate logistic regression analysis. OR for survival for adrenaline vs. no-adrenaline adjusted for confounders was 0.52 (95% CI: 0.29, 0.92). Receiving adrenaline was associated with improved short-term survival, but decreased survival to hospital discharge and survival with favourable neurological outcome after OHCA. This post hoc survival analysis is in contrast to the previous intention-to-treat analysis of the same data, but agrees with previous non-randomized registry data. This shows limitations of non-randomized or non-intention-to-treat analyses. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Implementing voice over Internet protocol in mobile ad hoc network – analysing its features regarding efficiency, reliability and security

    Directory of Open Access Journals (Sweden)

    Naveed Ahmed Sheikh

    2014-05-01

    Full Text Available Providing secure and efficient real-time voice communication in mobile ad hoc network (MANET environment is a challenging problem. Voice over Internet protocol (VoIP has originally been developed over the past two decades for infrastructure-based networks. There are strict timing constraints for acceptable quality VoIP services, in addition to registration and discovery issues in VoIP end-points. In MANETs, ad hoc nature of networks and multi-hop wireless environment with significant packet loss and delays present formidable challenges to the implementation. Providing a secure real-time VoIP service on MANET is the main design objective of this paper. The authors have successfully developed a prototype system that establishes reliable and efficient VoIP communication and provides an extremely flexible method for voice communication in MANETs. The authors’ cooperative mesh-based MANET implementation can be used for rapidly deployable VoIP communication with survivable and efficient dynamic networking using open source software.

  14. A Proposal and Evaluation of Security Camera System at a Car Park in an Ad-Hoc Network

    Science.gov (United States)

    Uemura, Wataru; Murata, Masashi

    In recent year, ad-hoc network technology has gained attention, which consists of not access points and base stations but of wireless nodes. In this network, it is difficult to maintain the whole data flow because of the absence of access points as the network administrator when nodes share the data. This paper proposes the security camera system which has only nodes sharing the taken pictures and has the robustness against the data destroying. The sender node cannot know whether packets are received or not by neighboring nodes in broadcasting because of a unidirectional communication. So in our proposed method, the sender node selects the receiver node from neighboring nodes, and they communicate with each other. On the other hand, neighboring nodes listen to packets between the sender node and the receiver node. After that, this method guarantees nodes of more than 1 which receive a data in broadcasting. We construct the security camera system using wireless nodes with the IEEE 802.15.4 specification and show the performance for security. At last, using the simulator we show the efficiency in the large environment, and conclude this paper.

  15. A post-hoc subgroup analysis of outcomes in the first phase III clinical study of edaravone (MCI-186) in amyotrophic lateral sclerosis.

    Science.gov (United States)

    2017-10-01

    Our first phase III study failed to demonstrate efficacy of edaravone for amyotrophic lateral sclerosis (ALS) compared to placebo. Here, we performed post-hoc subgroup analysis to identify a subgroup in which edaravone might be expected to show efficacy. We focussed on two newly defined subgroups, EESP and dpEESP2y. The EESP was defined as the efficacy-expected subpopulation with % forced vital capacity of ≥80%, and ≥2 points for all item scores in the revised ALS functional rating scale (ALSFRS-R) score before treatment. The dpEESP2y was defined as the greater-efficacy-expected subpopulation within EESP having a diagnosis of 'definite' or 'probable' ALS according to the El Escorial revised Airlie House diagnostic criteria and onset of disease within two years. The primary endpoint of the post-hoc analysis was the change in the ALSFRS-R score during the 24-week treatment period. The intergroup differences of the least-squares mean change in the ALSFRS-R score ± standard error during treatment were 0.65 ± 0.78 (p = 0.4108) in the full analysis set, 2.20 ± 1.03 (p = 0.0360) in the EESP, and 3.01 ± 1.33 (p = 0.0270) in the dpEESP2y. Edaravone exhibited efficacy in the dpEESP2y subgroup. A further clinical study in patients meeting dpEESP2y criteria is warranted.

  16. Noise-Assisted Concurrent Multipath Traffic Distribution in Ad Hoc Networks

    Science.gov (United States)

    Murata, Masayuki

    2013-01-01

    The concept of biologically inspired networking has been introduced to tackle unpredictable and unstable situations in computer networks, especially in wireless ad hoc networks where network conditions are continuously changing, resulting in the need of robustness and adaptability of control methods. Unfortunately, existing methods often rely heavily on the detailed knowledge of each network component and the preconfigured, that is, fine-tuned, parameters. In this paper, we utilize a new concept, called attractor perturbation (AP), which enables controlling the network performance using only end-to-end information. Based on AP, we propose a concurrent multipath traffic distribution method, which aims at lowering the average end-to-end delay by only adjusting the transmission rate on each path. We demonstrate through simulations that, by utilizing the attractor perturbation relationship, the proposed method achieves a lower average end-to-end delay compared to other methods which do not take fluctuations into account. PMID:24319375

  17. Classification and Evaluation of Mobility Metrics for Mobility Model Movement Patterns in Mobile Ad-Hoc Networks

    OpenAIRE

    Santosh Kumar S C Sharma Bhupendra Suman

    2011-01-01

    A mobile ad hoc network is collection of self configuring and adaption of wireless link between communicating devices (mobile devices) to form an arbitrary topology and multihop wireless connectivity without the use of existing infrastructure. It requires efficient dynamic routing protocol to determine the routes subsequent to a set of rules that enables two or more devices to communicate with each others. This paper basically classifies and evaluates the mobility metrics into two categories-...

  18. GSETT-3: testing the experimental international seismic monitoring system

    International Nuclear Information System (INIS)

    Ringdal, Frode

    1995-01-01

    Global seismic monitoring system has been developed by the Conference on Disarmaments (CDs) ad hoc group of scientific experts to consider international cooperative measures to detect and identify seismic events (the GSE), based in Geneva. In the course of its work, the GSE has conducted two large-scale global technical tests, Global Seismic Events Technical Test-1 (GSETT-1) in 1984 and GSETT-2 in 1991. The GSE has now embarked upon its third and most ambitious technical test, GSETT-3, which will encompass the development, testing and evaluation of a working prototype of the eventual Comprehensive Test Ban Treaty (CTBT) seismic monitoring system

  19. Halogenated organic contaminants (HOCs) in sediment from a highly eutrophicated lake, China: occurrence, distribution and mass inventories.

    Science.gov (United States)

    Wang, Ji-Zhong; Liu, Liang-Ying; Zhang, Kai; Liang, Bo; Li, Guo-Lian; Chen, Tian-Hu

    2012-11-01

    Halogenated organic contaminants (HOCs) including 16 polybrominated diphenyl ethers (PBDEs) and 37 polychlorinated biphenyls (PCBs) were determined in 49 surfacial sediments from Chaohu Lake, a highly eutrophicated lake, China. PBDEs were detected in almost samples with the range of the total concentration (defined as Σ(16)PBDEs) from 0.84 to 86.6 ng g(-1). Compared with the occurrence of PBDEs in Pearl River Delta and Yangtze River Delta in China, lower percentage of BDE-209 over the concentration of Σ(16)PBDEs was inferred by the high-volume application of penta-BDE mixture product for local domestic furniture purpose. The total concentration of 37 PCBs (Σ(37)PCBs) ranged from 0.05 to 3.36 ng g(-1) with the most detection of PCB-1, -4, -52 and -71. Both the concentrations of Σ(16)PBDE and Σ(37)PCB poorly correlated with total organic carbon (TOC), suggesting the significant contribution of phytoplankton organic carbons to sediment TOC. The contamination by PBDEs and PCBs in western region of the lake was significantly more serious than in eastern lake. Our findings about the higher residues of PBDEs and PCBs in sediments at the estuary of Nanfei River compared to the other estuaries also supported the conclusion that urban area (Hefei city) was the main source of PBDEs and PCBs. The comparison with the concentration of HOC in the present study with those in other lacustrine sediments around the world suggested the contamination by PBDEs in Chaohu Lake is at middle of the global concentration range, whereas PCBs is at low end of the global range which could be elucidated by local economic development and historical usage of PBDEs and PCBs. The mass inventories of HOCs in the lake were estimated at 561 and 38 kg, which corresponds to only 0.000006% and 0.0001% of these global historical produce volumes, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. The Claim Tool Kit for ad hoc recognition of peer entities

    DEFF Research Database (Denmark)

    Seigneur, Jean-Marc; Jensen, Christian D.

    2005-01-01

    In ubiquitous/pervasive computing environments, it is envisaged that computing elements—entities—will start interacting in an ad hoc fashion. The peer-to-peer (p2p) paradigm is appealing for such types of interaction especially with JXTA, which supports the development of reusable p2p building...... blocks, which facilitate implementation on any smart device. However, the inability to rely on a centralised authentication infrastructure, the openness of the environment and the absence of an administrator (it is assumed to be too expensive to have a skilled administrator at hand due to the large...... number of peers) challenge the use of legacy authentication mechanisms. Supporting spontaneous interactions among previously unknown entities requires dynamic enrolment of strangers and unknown entities. Entity recognition (ER) is a process that is carried out each time an interaction happens between...

  1. Secure neighborhood discovery: A fundamental element for mobile ad hoc networking

    DEFF Research Database (Denmark)

    Papadimitratos, P.; Poturalski, M.; Schaller, P.

    2008-01-01

    Pervasive computing systems will likely be deployed in the near future, with the proliferation of wireless devices and the emergence of ad hoc networking as key enablers. Coping with mobility and the volatility of wireless communications in such systems is critical. Neighborhood discovery (ND......) - the discovery of devices directly reachable for communication or in physical proximity - becomes a fundamental requirement and building block for various applications. However, the very nature of wireless mobile networks makes it easy to abuse ND and thereby compromise the overlying protocols and applications....... Thus, providing methods to mitigate this vulnerability and secure ND is crucial. In this article we focus on this problem and provide definitions of neighborhood types and ND protocol properties, as well as a broad classification of attacks. Our ND literature survey reveals that securing ND is indeed...

  2. Broadcast Expenses Controlling Techniques in Mobile Ad-hoc Networks: A Survey

    Directory of Open Access Journals (Sweden)

    Naeem Ahmad

    2016-07-01

    Full Text Available The blind flooding of query packets in route discovery more often characterizes the broadcast storm problem, exponentially increases energy consumption of intermediate nodes and congests the entire network. In such a congested network, the task of establishing the path between resources may become very complex and unwieldy. An extensive research work has been done in this area to improve the route discovery phase of routing protocols by reducing broadcast expenses. The purpose of this study is to provide a comparative analysis of existing broadcasting techniques for the route discovery phase, in order to bring about an efficient broadcasting technique for determining the route with minimum conveying nodes in ad-hoc networks. The study is designed to highlight the collective merits and demerits of such broadcasting techniques along with certain conclusions that would contribute to the choice of broadcasting techniques.

  3. Cognitive radio network in vehicular ad-hoc network (VANET: A survey

    Directory of Open Access Journals (Sweden)

    Joanne Mun-Yee Lim

    2016-05-01

    Full Text Available Cognitive radio network and Vehicular Ad hoc Network (VANET are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges and performance metrics, for different cognitive radio VANET applications.

  4. Post-hoc analysis of randomised, placebo-controlled, double-blind study (MCI186-19) of edaravone (MCI-186) in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Takei, Koji; Takahashi, Fumihiro; Liu, Shawn; Tsuda, Kikumi; Palumbo, Joseph

    2017-10-01

    Post-hoc analyses of the ALS Functional Rating Scale-Revised (ALSFRS-R) score data, the primary endpoint in the 24-week double-blind placebo-controlled study of edaravone (MCI186-19, NCT01492686), were performed to confirm statistical robustness of the result. The previously reported original analysis had used a last observation carried forward (LOCF) method and also excluded patients with fewer than three completed treatment cycles. The post-hoc sensitivity analyses used different statistical methods as follows: 1) including all patients regardless of treatment cycles received (ALL LOCF); 2) a mixed model for repeated measurements (MMRM) analysis; and 3) the Combined Assessment of Function and Survival (CAFS) endpoint. Findings were consistent with the original primary analysis in showing superiority of edaravone over placebo. We also investigated the distribution of change in ALSFRS-R total score across all patients in the study as well as which ALSFRS-R items and domains may have contributed to the overall efficacy findings. The distribution of changes in ALSFRS-R total score from baseline to the end of cycle 6 (ALL LOCF) shifted in favour of edaravone compared to placebo. Edaravone was descriptively favoured for each ALSFRS-R item and each of the four ALSFRS-R domains at the end of cycle 6 (ALL LOCF), suggesting a generalised effect of edaravone in slowing functional decline across all anatomical regions. The effect of edaravone appeared to be similar in patients with bulbar onset and limb onset. Together, these observations would be consistent with its putative neuroprotective effects against the development of oxidative damage unspecific to anatomical regions.

  5. 78 FR 8145 - Sequence 24 Findings of the EISA 436(h) Ad-Hoc Review Group on Green Building Certification Systems

    Science.gov (United States)

    2013-02-05

    ... EISA 436(h) Ad-Hoc Review Group on Green Building Certification Systems AGENCY: Office of Federal High-Performance Green Buildings; Office of Government-wide Policy, General Services Administration. ACTION... Secretary of Energy that identifies a green building certification system(s) most likely to encourage a...

  6. Optimizing Transmission and Shutdown for Energy-Efficient Real-time Packet Scheduling in Clustered Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Rajkumar Ragunathan

    2005-01-01

    Full Text Available Energy efficiency is imperative to enable the deployment of ad hoc networks. Conventional power management focuses independently on the physical or MAC layer and approaches differ depending on the abstraction level. At the physical layer, the fundamental tradeoff between transmission rate and energy is exploited, which leads to transmit as slow as possible. At MAC level, power reduction techniques aim to transmit as fast as possible to maximize the radios power-off interval. The two approaches seem conflicting and it is not obvious which one is the most appropriate. We propose a transmission strategy that optimally mixes both techniques in a multiuser context. We present a cross-layer solution considering the transceiver power characteristics, the varying system load, and the dynamic channel constraints. Based on this, we derive a low-complexity online scheduling algorithm. Results considering an -ary quadrature amplitude modulation radio show that for a range of scenarios a large power reduction is achieved, compared to the case where only scaling or shutdown is considered.

  7. A Security Solution for IEEE 802.11's Ad-hoc Mode:Password-Authentication and Group Diffie-Hellman Key Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Emmanuel, Bresson; Olivier, Chevassut; David, Pointcheval

    2005-10-01

    The IEEE 802 standards ease the deployment of networkinginfrastructures and enable employers to accesscorporate networks whiletraveling. These standards provide two modes of communication calledinfrastructure and ad-hoc modes. A security solution for the IEEE802.11's infrastructure mode took several years to reach maturity andfirmware are still been upgraded, yet a solution for the ad-hoc modeneeds to be specified. The present paper is a first attempt in thisdirection. It leverages the latest developments in the area ofpassword-based authentication and (group) Diffie-Hellman key exchange todevelop a provably-secure key-exchange protocol for IEEE 802.11's ad-hocmode. The protocol allows users to securely join and leave the wirelessgroup at time, accommodates either a single-shared password orpairwise-shared passwords among the group members, or at least with acentral server; achieves security against dictionary attacks in theideal-hash model (i.e. random-oracles). This is, to the best of ourknowledge, the first such protocol to appear in the cryptographicliterature.

  8. Guppies Show Behavioural but Not Cognitive Sex Differences in a Novel Object Recognition Test.

    Directory of Open Access Journals (Sweden)

    Tyrone Lucon-Xiccato

    Full Text Available The novel object recognition (NOR test is a widely-used paradigm to study learning and memory in rodents. NOR performance is typically measured as the preference to interact with a novel object over a familiar object based on spontaneous exploratory behaviour. In rats and mice, females usually have greater NOR ability than males. The NOR test is now available for a large number of species, including fish, but sex differences have not been properly tested outside of rodents. We compared male and female guppies (Poecilia reticulata in a NOR test to study whether sex differences exist also for fish. We focused on sex differences in both performance and behaviour of guppies during the test. In our experiment, adult guppies expressed a preference for the novel object as most rodents and other species do. When we looked at sex differences, we found the two sexes showed a similar preference for the novel object over the familiar object, suggesting that male and female guppies have similar NOR performances. Analysis of behaviour revealed that males were more inclined to swim in the proximity of the two objects than females. Further, males explored the novel object at the beginning of the experiment while females did so afterwards. These two behavioural differences are possibly due to sex differences in exploration. Even though NOR performance is not different between male and female guppies, the behavioural sex differences we found could affect the results of the experiments and should be carefully considered when assessing fish memory with the NOR test.

  9. Switching to olanzapine long-acting injection from either oral olanzapine or any other antipsychotic: comparative post hoc analyses

    Directory of Open Access Journals (Sweden)

    Ciudad A

    2013-11-01

    Full Text Available Antonio Ciudad,1 Ernie Anand,2 Lovisa Berggren,3 Marta Casillas,4 Alexander Schacht,3 Elena Perrin5 1Department of Clinical Research and Development, Eli Lilly & Co, Madrid, Spain; 2Neuroscience Medical Affairs – EU, Lilly Research Centre, Windlesham, Surrey, UK; 3Global Statistical Sciences, Eli Lilly & Co, Bad Homburg, Germany; 4European Scientific Communications, Eli Lilly & Co, Madrid, Spain; 5Medical Department, Eli Lilly & Co, Suresnes, Paris, France Background: A considerable proportion of patients suffering from schizophrenia show suboptimal responses to oral antipsychotics due to inadequate adherence. Hence, they are likely to benefit from switching to a long-acting injectable formulation. These post hoc analyses assessed the clinical effects of switching to olanzapine long-acting injection (OLAI from either oral olanzapine (OLZ or other antipsychotics (non-OLZ. Methods: Post hoc analyses were done based on two randomized studies (one short-term, one long-term conducted in patients suffering from schizophrenia and treated with OLAI. The short-term study was an 8-week placebo-controlled, double-blind trial in acute patients, and the long-term study was a 2-year, oral olanzapine-controlled, open-label, follow-up of stabilized outpatients. Results: These analyses used data from 62 OLAI-treated patients (12 switched from OLZ, 50 from non-OLZ from the short-term study and 190 OLAI-treated patients (56 switched from OLZ, 134 from non-OLZ from the long-term study. Kaplan–Meier survival analyses of time to all-cause discontinuation of OLAI treatment did not differ significantly between OLZ and non-OLZ patients in the short-term study (P=0.209 or long-term study (P=0.448. Similarly, the proportions of OLZ and non-OLZ patients that discontinued OLAI were not statistically different in the short-term (16.7% versus 36.0%, respectively; P=0.198 or long-term (57.1% versus 47.8% respectively; P=0.238 studies. In the short-term study, no

  10. An enhanced performance through agent-based secure approach for mobile ad hoc networks

    Science.gov (United States)

    Bisen, Dhananjay; Sharma, Sanjeev

    2018-01-01

    This paper proposes an agent-based secure enhanced performance approach (AB-SEP) for mobile ad hoc network. In this approach, agent nodes are selected through optimal node reliability as a factor. This factor is calculated on the basis of node performance features such as degree difference, normalised distance value, energy level, mobility and optimal hello interval of node. After selection of agent nodes, a procedure of malicious behaviour detection is performed using fuzzy-based secure architecture (FBSA). To evaluate the performance of the proposed approach, comparative analysis is done with conventional schemes using performance parameters such as packet delivery ratio, throughput, total packet forwarding, network overhead, end-to-end delay and percentage of malicious detection.

  11. Análisis de la aplicación de un sistema de actividad ad hoc para la promoción de habilidades metacognitivas de alfabetización académica Analysis Of Results Of Application Of System Of Activity Ad Hoc For The Promotion Of Abilities Metacognition Of Academic Alphabetization

    Directory of Open Access Journals (Sweden)

    María Elena Colombo

    2008-12-01

    Full Text Available Nuestro proyecto de investigación aborda una de las problemáticas de la enseñanza universitaria: la promoción de habilidades metacognitivas de alfabetización académica (PHMAA. El marco teórico adoptado corresponde a la Psicología Histórico-Cultural. Es una investigación cualitativa, según el modelo de investigación "estudio evolutivo del trabajo"que se realizó en contextos naturales de interacción áulica universitaria con un diseño longitudinal que abordó el estudio de los mismos grupos de alumnos en un lapso cuatrimestral para la misma cohorte 2006. La unidad de análisis escogida fue el "sistema de actividad áulico universitario". Se trabajó con dos muestras: una para el sistema de actividad artificial ad hoc y otra para el sistema de actividad tradicional, las que fueron analizadas y comparadas. Se utilizaron artefactos mediadores dentro del sistema ad hoc para la PHMAA. En el presente artículo se exponen los resultados del análisis y la comparación de evaluaciones escritas de los alumnos de ambos grupos.In our research project we examine one of the main issues on university level teaching: the promotion of metacognitive skills in academic literacy process (PHMAA in Spanish. The theoretical framework used is Historical - Cultural Psychology. It is a qualitative research, along the lines of investigation "evolutionary study of work" that took place in contexts of natural interaction classroom university with a design that addressed the longitudinal study of the same groups of students within four months for the same cohort 2006. The unit of analysis is chosen the "system activity classroom university." We worked with two samples: one for the system of artificial ad hoc activity and one for the traditional system, which were analyzed and compared. Mediators devices were used within the ad hoc system for PHMAA. In this article outlines the results of the analysis and comparison of written assessments of students in both

  12. Robust On-Demand Multipath Routing with Dynamic Path Upgrade for Delay-Sensitive Data over Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Sunil Kumar

    2013-01-01

    Full Text Available Node mobility in mobile ad hoc networks (MANETs causes frequent route breakages and intermittent link stability. In this paper, we introduce a robust routing scheme, known as ad hoc on-demand multipath distance vector with dynamic path update (AOMDV-DPU, for delay-sensitive data transmission over MANET. The proposed scheme improves the AOMDV scheme by incorporating the following features: (i a routing metric based on the combination of minimum hops and received signal strength indicator (RSSI for discovery of reliable routes; (ii a local path update mechanism which strengthens the route, reduces the route breakage frequency, and increases the route longevity; (iii a keep alive mechanism for secondary route maintenance which enables smooth switching between routes and reduces the route discovery frequency; (iv a packet salvaging scheme to improve packet delivery in the event of a route breakage; and (v low HELLO packet overhead. The simulations are carried out in ns-2 for varying node speeds, number of sources, and traffic load conditions. Our AOMDV-DPU scheme achieves significantly higher throughput, lower delay, routing overhead, and route discovery frequency and latency compared to AOMDV. For H.264 compressed video traffic, AOMDV-DPU scheme achieves 3 dB or higher PSNR gain over AOMDV at both low and high node speeds.

  13. A high performance, ad-hoc, fuzzy query processing system for relational databases

    Science.gov (United States)

    Mansfield, William H., Jr.; Fleischman, Robert M.

    1992-01-01

    Database queries involving imprecise or fuzzy predicates are currently an evolving area of academic and industrial research. Such queries place severe stress on the indexing and I/O subsystems of conventional database environments since they involve the search of large numbers of records. The Datacycle architecture and research prototype is a database environment that uses filtering technology to perform an efficient, exhaustive search of an entire database. It has recently been modified to include fuzzy predicates in its query processing. The approach obviates the need for complex index structures, provides unlimited query throughput, permits the use of ad-hoc fuzzy membership functions, and provides a deterministic response time largely independent of query complexity and load. This paper describes the Datacycle prototype implementation of fuzzy queries and some recent performance results.

  14. Energy Efficient Link Aware Routing with Power Control in Wireless Ad Hoc Networks.

    Science.gov (United States)

    Katiravan, Jeevaa; Sylvia, D; Rao, D Srinivasa

    2015-01-01

    In wireless ad hoc networks, the traditional routing protocols make the route selection based on minimum distance between the nodes and the minimum number of hop counts. Most of the routing decisions do not consider the condition of the network such as link quality and residual energy of the nodes. Also, when a link failure occurs, a route discovery mechanism is initiated which incurs high routing overhead. If the broadcast nature and the spatial diversity of the wireless communication are utilized efficiently it becomes possible to achieve improvement in the performance of the wireless networks. In contrast to the traditional routing scheme which makes use of a predetermined route for packet transmission, such an opportunistic routing scheme defines a predefined forwarding candidate list formed by using single network metrics. In this paper, a protocol is proposed which uses multiple metrics such as residual energy and link quality for route selection and also includes a monitoring mechanism which initiates a route discovery for a poor link, thereby reducing the overhead involved and improving the throughput of the network while maintaining network connectivity. Power control is also implemented not only to save energy but also to improve the network performance. Using simulations, we show the performance improvement attained in the network in terms of packet delivery ratio, routing overhead, and residual energy of the network.

  15. Energy Efficient Link Aware Routing with Power Control in Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Jeevaa Katiravan

    2015-01-01

    Full Text Available In wireless ad hoc networks, the traditional routing protocols make the route selection based on minimum distance between the nodes and the minimum number of hop counts. Most of the routing decisions do not consider the condition of the network such as link quality and residual energy of the nodes. Also, when a link failure occurs, a route discovery mechanism is initiated which incurs high routing overhead. If the broadcast nature and the spatial diversity of the wireless communication are utilized efficiently it becomes possible to achieve improvement in the performance of the wireless networks. In contrast to the traditional routing scheme which makes use of a predetermined route for packet transmission, such an opportunistic routing scheme defines a predefined forwarding candidate list formed by using single network metrics. In this paper, a protocol is proposed which uses multiple metrics such as residual energy and link quality for route selection and also includes a monitoring mechanism which initiates a route discovery for a poor link, thereby reducing the overhead involved and improving the throughput of the network while maintaining network connectivity. Power control is also implemented not only to save energy but also to improve the network performance. Using simulations, we show the performance improvement attained in the network in terms of packet delivery ratio, routing overhead, and residual energy of the network.

  16. Frame Transmission Efficiency-Based Cross-Layer Congestion Notification Scheme in Wireless Ad Hoc Networks.

    Science.gov (United States)

    He, Huaguang; Li, Taoshen; Feng, Luting; Ye, Jin

    2017-07-15

    Different from the traditional wired network, the fundamental cause of transmission congestion in wireless ad hoc networks is medium contention. How to utilize the congestion state from the MAC (Media Access Control) layer to adjust the transmission rate is core work for transport protocol design. However, recent works have shown that the existing cross-layer congestion detection solutions are too complex to be deployed or not able to characterize the congestion accurately. We first propose a new congestion metric called frame transmission efficiency (i.e., the ratio of successful transmission delay to the frame service delay), which describes the medium contention in a fast and accurate manner. We further present the design and implementation of RECN (ECN and the ratio of successful transmission delay to the frame service delay in the MAC layer, namely, the frame transmission efficiency), a general supporting scheme that adjusts the transport sending rate through a standard ECN (Explicit Congestion Notification) signaling method. Our method can be deployed on commodity switches with small firmware updates, while making no modification on end hosts. We integrate RECN transparently (i.e., without modification) with TCP on NS2 simulation. The experimental results show that RECN remarkably improves network goodput across multiple concurrent TCP flows.

  17. Accurate 3D Localization Method for Public Safety Applications in Vehicular Ad-hoc Networks

    KAUST Repository

    Ansari, Abdul Rahim

    2018-04-10

    Vehicular ad hoc networks (VANETs) represent a very promising research area because of their ever increasing demand, especially for public safety applications. In VANETs vehicles communicate with each other to exchange road maps and traffic information. In many applications, location-based services are the main service, and localization accuracy is the main problem. VANETs also require accurate vehicle location information in real time. To fulfill this requirement, a number of algorithms have been proposed; however, the location accuracy required for public safety applications in VANETs has not been achieved. In this paper, an improved subspace algorithm is proposed for time of arrival (TOA) measurements in VANETs localization. The proposed method gives a closed-form solution and it is robust for large measurement noise, as it is based on the eigen form of a scalar product and dimensionality. Furthermore, we developed the Cramer-Rao Lower Bound (CRLB) to evaluate the performance of the proposed 3D VANETs localization method. The performance of the proposed method was evaluated by comparison with the CRLB and other localization algorithms available in the literature through numerous simulations. Simulation results show that the proposed 3D VANETs localization method is better than the literature methods especially for fewer anchors at road side units and large noise variance.

  18. Enhancing the selection of backoff interval using fuzzy logic over wireless Ad Hoc networks.

    Science.gov (United States)

    Ranganathan, Radha; Kannan, Kathiravan

    2015-01-01

    IEEE 802.11 is the de facto standard for medium access over wireless ad hoc network. The collision avoidance mechanism (i.e., random binary exponential backoff-BEB) of IEEE 802.11 DCF (distributed coordination function) is inefficient and unfair especially under heavy load. In the literature, many algorithms have been proposed to tune the contention window (CW) size. However, these algorithms make every node select its backoff interval between [0, CW] in a random and uniform manner. This randomness is incorporated to avoid collisions among the nodes. But this random backoff interval can change the optimal order and frequency of channel access among competing nodes which results in unfairness and increased delay. In this paper, we propose an algorithm that schedules the medium access in a fair and effective manner. This algorithm enhances IEEE 802.11 DCF with additional level of contention resolution that prioritizes the contending nodes according to its queue length and waiting time. Each node computes its unique backoff interval using fuzzy logic based on the input parameters collected from contending nodes through overhearing. We evaluate our algorithm against IEEE 802.11, GDCF (gentle distributed coordination function) protocols using ns-2.35 simulator and show that our algorithm achieves good performance.

  19. SVANET: A smart vehicular ad hoc network for efficient data transmission with wireless sensors.

    Science.gov (United States)

    Sahoo, Prasan Kumar; Chiang, Ming-Jer; Wu, Shih-Lin

    2014-11-25

    Wireless sensors can sense any event, such as accidents, as well as icy roads, and can forward the rescue/warning messages through intermediate vehicles for any necessary help. In this paper, we propose a smart vehicular ad hoc network (SVANET) architecture that uses wireless sensors to detect events and vehicles to transmit the safety and non-safety messages efficiently by using different service channels and one control channel with different priorities. We have developed a data transmission protocol for the vehicles in the highway, in which data can be forwarded with the help of vehicles if they are connected with each other or data can be forwarded with the help of nearby wireless sensors. Our data transmission protocol is designed to increase the driving safety, to prevent accidents and to utilize channels efficiently by adjusting the control and service channel time intervals dynamically. Besides, our protocol can transmit information to vehicles in advance, so that drivers can decide an alternate route in case of traffic congestion. For various data sharing, we design a method that can select a few leader nodes among vehicles running along a highway to broadcast data efficiently. Simulation results show that our protocol can outperform the existing standard in terms of the end to end packet delivery ratio and latency.

  20. Energy Aware Cluster-Based Routing in Flying Ad-Hoc Networks.

    Science.gov (United States)

    Aadil, Farhan; Raza, Ali; Khan, Muhammad Fahad; Maqsood, Muazzam; Mehmood, Irfan; Rho, Seungmin

    2018-05-03

    Flying ad-hoc networks (FANETs) are a very vibrant research area nowadays. They have many military and civil applications. Limited battery energy and the high mobility of micro unmanned aerial vehicles (UAVs) represent their two main problems, i.e., short flight time and inefficient routing. In this paper, we try to address both of these problems by means of efficient clustering. First, we adjust the transmission power of the UAVs by anticipating their operational requirements. Optimal transmission range will have minimum packet loss ratio (PLR) and better link quality, which ultimately save the energy consumed during communication. Second, we use a variant of the K-Means Density clustering algorithm for selection of cluster heads. Optimal cluster heads enhance the cluster lifetime and reduce the routing overhead. The proposed model outperforms the state of the art artificial intelligence techniques such as Ant Colony Optimization-based clustering algorithm and Grey Wolf Optimization-based clustering algorithm. The performance of the proposed algorithm is evaluated in term of number of clusters, cluster building time, cluster lifetime and energy consumption.

  1. Energy Aware Cluster-Based Routing in Flying Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    Farhan Aadil

    2018-05-01

    Full Text Available Flying ad-hoc networks (FANETs are a very vibrant research area nowadays. They have many military and civil applications. Limited battery energy and the high mobility of micro unmanned aerial vehicles (UAVs represent their two main problems, i.e., short flight time and inefficient routing. In this paper, we try to address both of these problems by means of efficient clustering. First, we adjust the transmission power of the UAVs by anticipating their operational requirements. Optimal transmission range will have minimum packet loss ratio (PLR and better link quality, which ultimately save the energy consumed during communication. Second, we use a variant of the K-Means Density clustering algorithm for selection of cluster heads. Optimal cluster heads enhance the cluster lifetime and reduce the routing overhead. The proposed model outperforms the state of the art artificial intelligence techniques such as Ant Colony Optimization-based clustering algorithm and Grey Wolf Optimization-based clustering algorithm. The performance of the proposed algorithm is evaluated in term of number of clusters, cluster building time, cluster lifetime and energy consumption.

  2. Development of Software and Strategies for Battery Management System Testing on HIL Simulator

    DEFF Research Database (Denmark)

    Fleischer, Christian; Sauer, Dirk Uwe; Barreras, Jorge Varela

    2016-01-01

    of complexity of the tests, the higher the demands for ad hoc development of SW and strategies. With regard to the latter, there is not a universal definition and there are different points of view. Therefore different strategies may be followed, which can be classified into many different ways according...

  3. Improvement over the OLSR Routing Protocol in Mobile Ad Hoc Networks by Eliminating the Unnecessary Loops

    OpenAIRE

    Shahram Behzad; Reza Fotohi; Shahram Jamali

    2013-01-01

    Mobile ad hoc networks are type of wireless networks in which any kind of infrastructure is not used, i.e. there are no infrastructures such as routers or switches or anything else on the network that can be used to support the network structure and the nodes has mobility. The purpose of this paper is to provide a better quality of the package delivery rate and the throughput, that is in need of powerful routing protocol standards, which can guarantee delivering of the packages to destination...

  4. Modern foreign language teachers - don't leave those kids alone! Linguistic-cultural "give and take" in an ad-hoc tutoring scheme

    Science.gov (United States)

    Leroy, Norah

    2017-08-01

    This paper addresses the theme of social inclusion through language learning. The focus is on an ad-hoc tutoring scheme set up between newly arrived British migrant pupils and French monolingual pupils in a small secondary school in the south-west of France. Though the original objective of this tutoring scheme was to improve the English skills of the younger pupils, feedback reports indicated that it also had a positive impact on the relationship between the British migrant pupils and their French peers. Teachers believed that those involved participated more fully in class, and appeared more self-assured and generally happy thanks to the interpersonal relationships this scheme helped to forge. This study demonstrates the necessity of analysing the socio-cultural context migrants may find themselves in, in order to identify potential challenges. The ad-hoc tutoring scheme described here is an example of how language learning can support the integration and inclusion of "new generation" migrants into everyday school life.

  5. An epidemic model for biological data fusion in ad hoc sensor networks

    Science.gov (United States)

    Chang, K. C.; Kotari, Vikas

    2009-05-01

    Bio terrorism can be a very refined and a catastrophic approach of attacking a nation. This requires the development of a complete architecture dedicatedly designed for this purpose which includes but is not limited to Sensing/Detection, Tracking and Fusion, Communication, and others. In this paper we focus on one such architecture and evaluate its performance. Various sensors for this specific purpose have been studied. The accent has been on use of Distributed systems such as ad-hoc networks and on application of epidemic data fusion algorithms to better manage the bio threat data. The emphasis has been on understanding the performance characteristics of these algorithms under diversified real time scenarios which are implemented through extensive JAVA based simulations. Through comparative studies on communication and fusion the performance of channel filter algorithm for the purpose of biological sensor data fusion are validated.

  6. Reliability analysis of cluster-based ad-hoc networks

    International Nuclear Information System (INIS)

    Cook, Jason L.; Ramirez-Marquez, Jose Emmanuel

    2008-01-01

    The mobile ad-hoc wireless network (MAWN) is a new and emerging network scheme that is being employed in a variety of applications. The MAWN varies from traditional networks because it is a self-forming and dynamic network. The MAWN is free of infrastructure and, as such, only the mobile nodes comprise the network. Pairs of nodes communicate either directly or through other nodes. To do so, each node acts, in turn, as a source, destination, and relay of messages. The virtue of a MAWN is the flexibility this provides; however, the challenge for reliability analyses is also brought about by this unique feature. The variability and volatility of the MAWN configuration makes typical reliability methods (e.g. reliability block diagram) inappropriate because no single structure or configuration represents all manifestations of a MAWN. For this reason, new methods are being developed to analyze the reliability of this new networking technology. New published methods adapt to this feature by treating the configuration probabilistically or by inclusion of embedded mobility models. This paper joins both methods together and expands upon these works by modifying the problem formulation to address the reliability analysis of a cluster-based MAWN. The cluster-based MAWN is deployed in applications with constraints on networking resources such as bandwidth and energy. This paper presents the problem's formulation, a discussion of applicable reliability metrics for the MAWN, and illustration of a Monte Carlo simulation method through the analysis of several example networks

  7. The congestion control algorithm based on queue management of each node in mobile ad hoc networks

    Science.gov (United States)

    Wei, Yifei; Chang, Lin; Wang, Yali; Wang, Gaoping

    2016-12-01

    This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. As the network load increases, local congestion of mobile ad hoc network may lead to network performance degradation, hot node's energy consumption increase even failure. If small energy nodes congested because of forwarding data packets, then when it is used as the source node will cause a lot of packet loss. This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. Controlling nodes buffer queue in different levels of congestion area probability by adjusting the upper limits and lower limits, thus nodes can adjust responsibility of forwarding data packets according to their own situation. The proposed algorithm will slow down the send rate hop by hop along the data package transmission direction from congestion node to source node so that to prevent further congestion from the source node. The simulation results show that, the algorithm can better play the data forwarding ability of strong nodes, protect the weak nodes, can effectively alleviate the network congestion situation.

  8. Optical emissions from the dissociative recombination of N{sub 2}H{sup +}, HCO{sup +}, HOC{sup +}, and HNC{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, R [Department of Physics and Astronomy University of Pittsburgh, Pittsburgh, PA 15260 (United States); Golde, M F [Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Rosati, R E [Smithsonian Astrophysical Observatory, 60 Garden St. MS-50 Cambridge, MA, 02138 (United States); Pappas, D [Army Research Laboratory, 4600 Deer Creek Loop, Aberdeen Proving Ground, MD (United States); Skrzypkowski, M P, E-mail: rj@pitt.ed [Prometheus Energy Company, 3311 S. 120th Place Suite 100, Seattle, WA 98168 (United States)

    2009-11-15

    We present recent flowing-afterglow measurements of branching fractions for electronically and vibrationally excited products arising from the dissociative recombination of N{sub 2}H{sup +}, HCO{sup +}, HOC{sup +}, and HNC{sup +} ions with thermal electrons. State-specific yields were derived by fitting the observed, spatially resolved emission band intensities to models that simulate all ion-chemical processes, recombination, diffusion, and gas mixing.

  9. Protective effect of yerba mate intake on the cardiovascular system: a post hoc analysis study in postmenopausal women

    OpenAIRE

    da Veiga, D.T.A.; Bringhenti, R.; Copes, R.; Tatsch, E.; Moresco, R.N.; Comim, F.V.; Premaor, M.O.

    2018-01-01

    The prevalence of cardiovascular and metabolic diseases is increased in postmenopausal women, which contributes to the burden of illnesses in this period of life. Yerba mate (Ilex paraguariensis) is a native bush from Southern South America. Its leaves are rich in phenolic components, which may have antioxidant, vasodilating, hypocholesterolemic, and hypoglycemic proprieties. This post hoc analysis of the case-control study nested in the Obesity and Bone Fracture Cohort evaluated the consumpt...

  10. Reuse of the test information

    International Nuclear Information System (INIS)

    Markoski, Branko; Malbaski, Dushan; Hotomski, Petar

    2006-01-01

    Within software's life cycle, program testing is very important, since quality of specification demands, design and application must be proven. Testing of large and complicated programs must be done as systematically as possible, in order to obtain reliability. In case of large and comple systems and their operating systems ad hoc testing is used, which often could not prove quality or validity according to specification, construction or application. Validation and verification are terms often connected to program testing. Verification is checkup of testing of objects (or programs) in order to determine are they in accordance with specifications. Verification contains analysis, inspection, trying, as well as testing of program. About testing the software, ordinarily we do statically analyses (eploring of basic programs, searching for primary problems and collecting data's without eecuting the program) and dynamic analyses (eploring behavior of program in eecuting, so we acquire the data about the ways of eecuting, chronological sections and integrity of testing). Every company, which educes the software, is performing tests of their products, and the software from market usually contents comple variants of defects. Sometimes it is difficult to understand how it is possible that the test omits so obvious error.

  11. An Eco-Driving Advisory System for Continuous Signalized Intersections by Vehicular Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Wei-Hsun Lee

    2018-01-01

    Full Text Available With the vehicular ad hoc network (VANET technology which support vehicle-to-vehicle (V2V and vehicle to road side unit (V2R/R2V communications, vehicles can preview the intersection signal plan such as signal countdown message. In this paper, an ecodriving advisory system (EDAS is proposed to reduce CO2 emissions and energy consumption by letting the vehicle continuously pass through multiple intersections with the minimum possibilities of stops. We extend the isolated intersection model to multiple continuous intersections scenario. A hybrid method combining three strategies including maximized throughput model (MTM, smooth speed model (SSM, and minimized acceleration and deceleration (MinADM is designed, and it is compared with related works maximized throughput model (MaxTM, open traffic light control model (OTLCM, and predictive cruise control (PCC models. Some issues for the practical application including safe car following, queue clearing, and gliding mode are discussed and conquered. Simulation results show that the proposed model outperforms OTLCM 25.1%~81.2% in the isolated intersection scenario for the CO2 emissions and 20.5%~84.3% in averaged travel time. It also performs better than the compared PCC model in CO2 emissions (19.9%~31.2% as well as travel time (24.5%~35.9% in the multiple intersections scenario.

  12. Concurrent Transmission Based on Channel Quality in Ad Hoc Networks: A Game Theoretic Approach

    Science.gov (United States)

    Chen, Chen; Gao, Xinbo; Li, Xiaoji; Pei, Qingqi

    In this paper, a decentralized concurrent transmission strategy in shared channel in Ad Hoc networks is proposed based on game theory. Firstly, a static concurrent transmissions game is used to determine the candidates for transmitting by channel quality threshold and to maximize the overall throughput with consideration of channel quality variation. To achieve NES (Nash Equilibrium Solution), the selfish behaviors of node to attempt to improve the channel gain unilaterally are evaluated. Therefore, this game allows each node to be distributed and to decide whether to transmit concurrently with others or not depending on NES. Secondly, as there are always some nodes with lower channel gain than NES, which are defined as hunger nodes in this paper, a hunger suppression scheme is proposed by adjusting the price function with interferences reservation and forward relay, to fairly give hunger nodes transmission opportunities. Finally, inspired by stock trading, a dynamic concurrent transmission threshold determination scheme is implemented to make the static game practical. Numerical results show that the proposed scheme is feasible to increase concurrent transmission opportunities for active nodes, and at the same time, the number of hunger nodes is greatly reduced with the least increase of threshold by interferences reservation. Also, the good performance on network goodput of the proposed model can be seen from the results.

  13. SVANET: A Smart Vehicular Ad Hoc Network for Efficient Data Transmission with Wireless Sensors

    Directory of Open Access Journals (Sweden)

    Prasan Kumar Sahoo

    2014-11-01

    Full Text Available Wireless sensors can sense any event, such as accidents, as well as icy roads, and can forward the rescue/warning messages through intermediate vehicles for any necessary help. In this paper, we propose a smart vehicular ad hoc network (SVANET architecture that uses wireless sensors to detect events and vehicles to transmit the safety and non-safety messages efficiently by using different service channels and one control channel with different priorities. We have developed a data transmission protocol for the vehicles in the highway, in which data can be forwarded with the help of vehicles if they are connected with each other or data can be forwarded with the help of nearby wireless sensors. Our data transmission protocol is designed to increase the driving safety, to prevent accidents and to utilize channels efficiently by adjusting the control and service channel time intervals dynamically. Besides, our protocol can transmit information to vehicles in advance, so that drivers can decide an alternate route in case of traffic congestion. For various data sharing, we design a method that can select a few leader nodes among vehicles running along a highway to broadcast data efficiently. Simulation results show that our protocol can outperform the existing standard in terms of the end to end packet delivery ratio and latency.

  14. Insight and Treatment Outcomes in Schizophrenia: Post-hoc Analysis of a Long-term, Double-blind Study Comparing Lurasidone and Quetiapine XR.

    Science.gov (United States)

    Harvey, Philip D; Siu, Cynthia O; Loebel, Antony D

    2017-12-01

    Objective: The objective of this post-hoc analysis was to evaluate the effect of lurasidone and quetiapine extended-release (XR) on insight and judgment and assess the longitudinal relationships between improvement in insight and cognitive performance, functional capacity, quality of well-being, and depressive symptoms in patients with schizophrenia. Design: Clinically unstable patients with schizophrenia (N=488) were randomized to once-daily, fixed-dose treatment with lurasidone 80mg, lurasidone 160mg, quetiapine XR 600mg, or placebo, followed by a long-term, double-blind, flexible-dose continuation study involving these agents. Results: Significantly greater improvement in insight and judgment (assessed by the Positive and Negative Syndrome Scale G12 item) for the lurasidone and quetiapine XR groups, compared to the placebo group, was observed at Week 6. Over a subsequent six-month continuation period, the flexible dose lurasidone group showed significantly greater improvement in insight from acute phase baseline compared to the flexible-dose quetiapine XR group (QXR-QXR) (p=0.032). Improvement in insight was significantly correlated with improvement in cognition ( p =0.014), functional capacity (p=0.006, UPSA-B), quality of well-being ( p =0.033, QWB), and depressive symptoms ( p =0.05, Montgomery-Åsberg Depression Rating Scale [MADRS] score) across treatment groups and study periods. Conclusion: In this post-hoc analysis, flexibly dosed lurasidone 40 to 160mg/d was found to be associated with significantly greater improvement in insight compared to flexibly dosed quetiapine XR 200 to 800mg/d over long-term treatment in patients with schizophrenia. Across treatment groups, improvement in insight and judgment was significantly associated with improvement in cognition, functional capacity, quality of well-being, and depressive symptoms over time.

  15. Implementing a Topology Management Algorithm for Mobile Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    Mrinal K. Naskar

    2008-01-01

    Full Text Available In this paper, we propose to maintain the topology of a MANET by suitably selecting multiple coordinators among the nodes constituting the MANET. The maintenance of topology in a mobile ad–hoc network is of primary importance because the routing techniques can only work if we have a connected network. Thus of the burning issues at present is to device algorithms which ensure that the network topology is always maintained. The basic philosophy behind our algorithm is to isolate two coordinators amongst the system based on positional data. Once elected, they are entrusted with the responsibility to emit signals of different frequencies while the other nodes individually decide the logic they need to follow in order to maintain the topology, thereby greatly reducing the overhead. As far as our knowledge goes, we are the first ones to introduce the concept of multiple coordinators which not only reduces the workload of the coordinator, but also eliminates the need of different signal ranges thereby ensuring greater efficiency. We have simulated the algorithm with the help of a number of robots using embedded systems. The results we have obtained have been quite encouraging.

  16. Crude extract and fractions from Eugenia uniflora Linn leaves showed anti-inflammatory, antioxidant, and antibacterial activities.

    Science.gov (United States)

    Falcão, Tamires Rocha; de Araújo, Aurigena Antunes; Soares, Luiz Alberto Lira; de Moraes Ramos, Rhayanne Thaís; Bezerra, Isabelle Cristinne Ferraz; Ferreira, Magda Rhayanny Assunção; de Souza Neto, Manoel André; Melo, Maria Celeste Nunes; de Araújo, Raimundo Fernandes; de Aguiar Guerra, Andreza Conceição Véras; de Medeiros, Juliana Silva; Guerra, Gerlane Coelho Bernardo

    2018-03-09

    This study showed phytochemical composition and evaluates the anti-inflammatory, and analgesic activities of crude extract (CE) and fractions from E. uniflora Linn leaves. Polyphenols present in crude extract (CE), in aqueous fraction (AqF), and ethyl acetate (EAF) treated fractions from E. uniflora Linn leaves were shown by chromatographic analysis in order to conduct a phytochemical characterization. Antibacterial activity was evaluated based on minimum inhibitory concentrations (MICs) determined using the agar dilution method. Doses of 50, 100, and 200 mg/kg of the CE and fractions were applied for conducting in vivo models (male Swiss mice, 8-10 weeks old). The peritonitis experimental model was induced by carrageenan following of Myeloperoxidase activity (MPO), Total glutathione and malondialdehyde (MDA), IL-1β and TNF-α levels by spectroscopic UV/VIS analysis. Antinociceptive activity was evaluated based on an abdominal writhing model and hot plate test. The results were statistically evaluated using one-way analysis of variance (ANOVA), followed by Bonferroni's post-hoc test. The level of statistical significance was p fractions obtained from E. uniflora Linn leaves (0.05-0.87%w/w, 0.20-0.32%w/w, and 1.71-6.56%w/w, respectively). In general, the CE had lower MIC values than the fractions, including the lowest MIC against the MRSA strain. The CE and AqF also significantly reduced leukocyte migration and MPO activity (p fractions exhibited an antioxidant effect (p fractions from the studied E. uniflora Linn leaves exhibited antibacterial, anti-inflammatory, antioxidant, and analgesic activity in the performed assays.

  17. EEG Spectral Analysis in Serious Gaming: An Ad Hoc Experimental Application

    Directory of Open Access Journals (Sweden)

    Minchev Z.

    2009-12-01

    Full Text Available The application of serious gaming technology in different areas of human knowledge for learning is raising the question of quantitative measurement of the training process quality. In the present paper a pilot study of 10 healthy volunteers' EEG spectra is performed for ad hoc selected game events ('win' and 'lose' via continuous wavelet transform (real and complex on the basis of the Morlet mother wavelet function and S-transformation. The results have shown a general decrease of the alpha rhythms power spectra frequencies for the 'lose' events and increase for the 'win' events. This fact corresponds to an opposite behaviour of the theta rhythm of the players for the same 'win' and 'lose' events. Additionally, the frequency changes in the alpha1 (8-10.5 Hz, alpha2 (10.5-13 Hz and theta2 rhythms (6-8 Hz were supposed to be a phenomena related to positive and negative emotions appearance in the EEG activity of the players regarding the selected 'win' and 'lose' states.

  18. Lenient vs. strict rate control in patients with atrial fibrillation and heart failure: a post-hoc analysis of the RACE II study

    NARCIS (Netherlands)

    Mulder, Bart A.; van Veldhuisen, Dirk J.; Crijns, Harry J. G. M.; Tijssen, Jan G. P.; Hillege, Hans L.; Alings, Marco; Rienstra, Michiel; Groenveld, Hessel F.; van den Berg, Maarten P.; van Gelder, Isabelle C.

    2013-01-01

    It is unknown whether lenient rate control is an acceptable strategy in patients with AF and heart failure. We evaluated differences in outcome in patients with AF and heart failure treated with lenient or strict rate control. This post-hoc analysis of the RACE II trial included patients with an

  19. Multiobjective Reinforcement Learning for Traffic Signal Control Using Vehicular Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Houli Duan

    2010-01-01

    Full Text Available We propose a new multiobjective control algorithm based on reinforcement learning for urban traffic signal control, named multi-RL. A multiagent structure is used to describe the traffic system. A vehicular ad hoc network is used for the data exchange among agents. A reinforcement learning algorithm is applied to predict the overall value of the optimization objective given vehicles' states. The policy which minimizes the cumulative value of the optimization objective is regarded as the optimal one. In order to make the method adaptive to various traffic conditions, we also introduce a multiobjective control scheme in which the optimization objective is selected adaptively to real-time traffic states. The optimization objectives include the vehicle stops, the average waiting time, and the maximum queue length of the next intersection. In addition, we also accommodate a priority control to the buses and the emergency vehicles through our model. The simulation results indicated that our algorithm could perform more efficiently than traditional traffic light control methods.

  20. Laboratory and test beam results from a large-area silicon drift detector

    CERN Document Server

    Bonvicini, V; Giubellino, P; Gregorio, A; Idzik, M; Kolojvari, A A; Montaño-Zetina, L M; Nouais, D; Petta, C; Rashevsky, A; Randazzo, N; Reito, S; Tosello, F; Vacchi, A; Vinogradov, L I; Zampa, N

    2000-01-01

    A very large-area (6.75*8 cm/sup 2/) silicon drift detector with integrated high-voltage divider has been designed, produced and fully characterised in the laboratory by means of ad hoc designed MOS injection electrodes. The detector is of the "butterfly" type, the sensitive area being subdivided into two regions with a maximum drift length of 3.3 cm. The device was also tested in a pion beam (at the CERN PS) tagged by means of a microstrip detector telescope. Bipolar VLSI front-end cells featuring a noise of 250 e/sup -/ RMS at 0 pF with a slope of 40 e/sup -//pF have been used to read out the signals. The detector showed an excellent stability and featured the expected characteristics. Some preliminary results will be presented. (12 refs).

  1. Post-hoc analysis of MCI186-17, the extension study to MCI186-16, the confirmatory double-blind, parallel-group, placebo-controlled study of edaravone in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Takahashi, Fumihiro; Takei, Koji; Tsuda, Kikumi; Palumbo, Joseph

    2017-10-01

    In the 24-week double-blind study of edaravone in ALS (MCI186-16), edaravone did not show a statistically significant difference versus placebo for the primary efficacy endpoint. For post-hoc analyses, two subpopulations were identified in which edaravone might be expected to show efficacy: the efficacy-expected subpopulation (EESP), defined by scores of ≥2 points on all 12 items of the ALS Functional Rating Scale-Revised (ALSFRS-R) and a percent predicted forced vital capacity (%FVC) ≥80% at baseline; and the definite/probable EESP 2 years (dpEESP2y) subpopulation which, in addition to EESP criteria, had definite or probable ALS diagnosed by El Escorial revised criteria, and disease duration of ≤2 years. In the 36-week extension study of MCI186-16, a 24-week double-blind comparison followed by 12 weeks of open-label edaravone (MCI186-17; NCT00424463), analyses of ALSFRS-R scores of the edaravone-edaravone group and edaravone-placebo group for the full analysis set (FAS) and EESP, as prospectively defined, were reported in a previous article. Here we additionally report results in patients who met dpEESP2y criteria at the baseline of MCI186-16. In the dpEESP2y, the difference in ALSFRS-R changes from 24 to 48 weeks between the edaravone-edaravone and edaravone-placebo groups was 2.79 (p = 0.0719), which was greater than the differences previously reported for the EESP and the FAS. The pattern of adverse events in the dpEESP2y did not show any additional safety findings to those from the earlier prospective study. In conclusion, this post-hoc analysis suggests a potential effect of edaravone between 24 and 48 weeks in patients meeting dpEESP2y criteria at baseline.

  2. Modification of irrational ideas and test anxiety through rational stage directed hypnotherapy [RSDH].

    Science.gov (United States)

    Boutin, G E; Tosi, D J

    1983-05-01

    Examined the effects of four treatment conditions on the modification of Irrational Ideas and test anxiety in female nursing students. The treatments were Rational Stage Directed Hypnotherapy, a cognitive behavioral approach that utilized hypnosis and vivid-emotive-imagery, a hypnosis-only treatment, a placebo condition, and a no-treatment control. The 48 Ss were assigned randomly to one of these treatment groups, which met for 1 hour per week for 6 consecutive weeks with in-vivo homework assignments also utilized. Statistically significant treatment effects on cognitive, affective, behavioral, and physiological measures were noted for both the RSDH and hypnosis group at the posttest and at a 2-month follow-up. Post-hoc analyses revealed the RSDH treatment group to be significantly more effective than the hypnosis only group on both the post- and follow-up tests. The placebo and control groups showed no significant effects either at post-treatment or at follow-up.

  3. Statistical Delay QoS Provisioning for Energy-Efficient Spectrum-Sharing Based Wireless Ad Hoc Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yichen Wang

    2016-01-01

    Full Text Available In this paper, we develop the statistical delay quality-of-service (QoS provisioning framework for the energy-efficient spectrum-sharing based wireless ad hoc sensor network (WAHSN, which is characterized by the delay-bound violation probability. Based on the established delay QoS provisioning framework, we formulate the nonconvex optimization problem which aims at maximizing the average energy efficiency of the sensor node in the WAHSN while meeting PU’s statistical delay QoS requirement as well as satisfying sensor node’s average transmission rate, average transmitting power, and peak transmitting power constraints. By employing the theories of fractional programming, convex hull, and probabilistic transmission, we convert the original fractional-structured nonconvex problem to the additively structured parametric convex problem and obtain the optimal power allocation strategy under the given parameter via Lagrangian method. Finally, we derive the optimal average energy efficiency and corresponding optimal power allocation scheme by employing the Dinkelbach method. Simulation results show that our derived optimal power allocation strategy can be dynamically adjusted based on PU’s delay QoS requirement as well as the channel conditions. The impact of PU’s delay QoS requirement on sensor node’s energy efficiency is also illustrated.

  4. An Intelligent and Fast Chaotic Encryption Using Digital Logic Circuits for Ad-Hoc and Ubiquitous Computing

    Directory of Open Access Journals (Sweden)

    Ankur Khare

    2016-05-01

    Full Text Available Delays added by the encryption process represent an overhead for smart computing devices in ad-hoc and ubiquitous computing intelligent systems. Digital Logic Circuits are faster than other computing techniques, so these can be used for fast encryption to minimize processing delays. Chaotic Encryption is more attack-resilient than other encryption techniques. One of the most attractive properties of cryptography is known as an avalanche effect, in which two different keys produce distinct cipher text for the same information. Important properties of chaotic systems are sensitivity to initial conditions and nonlinearity, which makes two similar keys that generate different cipher text a source of confusion. In this paper a novel fast and secure Chaotic Map-based encryption technique using 2’s Compliment (CET-2C has been proposed, which uses a logistic map which implies that a negligible difference in parameters of the map generates different cipher text. Cryptanalysis of the proposed algorithm shows the strength and security of algorithm and keys. Performance of the proposed algorithm has been analyzed in terms of running time, throughput and power consumption. It is to be shown in comparison graphs that the proposed algorithm gave better results compare to different algorithms like AES and some others.

  5. Functional expression of a proton-coupled organic cation (H+/OC antiporter in human brain capillary endothelial cell line hCMEC/D3, a human blood–brain barrier model

    Directory of Open Access Journals (Sweden)

    Shimomura Keita

    2013-01-01

    Full Text Available Abstract Background Knowledge of the molecular basis and transport function of the human blood–brain barrier (BBB is important for not only understanding human cerebral physiology, but also development of new central nervous system (CNS-acting drugs. However, few studies have been done using human brain capillary endothelial cells, because human brain materials are difficult to obtain. The purpose of this study is to clarify the functional expression of a proton-coupled organic cation (H+/OC antiporter in human brain capillary endothelial cell line hCMEC/D3, which has been recently developed as an in vitro human BBB model. Methods Diphenhydramine, [3H]pyrilamine and oxycodone were used as cationic drugs that proved to be H+/OC antiporter substrates. The in vitro uptake experiments by hCMEC/D3 cells were carried out under several conditions. Results Diphenhydramine and [3H]pyrilamine were both transported into hCMEC/D3 cells in a time- and concentration-dependent manner with Km values of 59 μM and 19 μM, respectively. Each inhibited uptake of the other in a competitive manner, suggesting that a common mechanism is involved in their transport. The diphenhydramine uptake was significantly inhibited by amantadine and quinidine, but not tetraethylammonium and 1-methyl-4-phenylpyridinium (substrates for well-known organic cation transporters. The uptake was inhibited by metabolic inhibitors, but was insensitive to extracellular sodium and membrane potential. Further, the uptake was increased by extracellular alkalization and intracellular acidification. These transport properties are completely consistent with those of previously characterized H+/OC antiporter in rat BBB. Conclusions The present results suggest that H+/OC antiporter is functionally expressed in hCMEC/D3 cells.

  6. Vehicle Assisted Data Delievery Technique To Control Data Dissemination In Vehicular AD - HOC Networks Vanets

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar

    2015-08-01

    Full Text Available Abstract Multi-hop data delivery through vehicular ad hoc networks is complicated by the fact that vehicular networks are highly mobile and frequently disconnected. To address this issue the idea of helper node is opted where a moving vehicles carries the packet until a new vehicle moves into its vicinity and forwards the packet. Different from existing helper node solution use of the predicable vehicle mobility is made which is limited by the traffic pattern and the road layout. Based on the existing traffic pattern a vehicle can find the next road to forward packet a vehicle can find the next road to forward the packet to reduce the delay. Several vehicle-assisted date delievery VADD protocol is proposed to forward the packet to the best road with the road with the lowest data delivery delay. Experiment results are used to evaluate the proposed solutions. Results show that the proposed VADD protocol outperform existing solution in terms of packet delivery ratio data packet delay and protocol overhead. Among the proposed VADD protocols the Hybrid probe HVADD protocol has much better performance. In this Solution the helper node technique is provider with which the helper node will contain destination node path and the path in routine table continuously changes with the help of helper node technique.

  7. ITER ECRH upper launcher torus diamond window – Prototyping, testing and qualification

    Energy Technology Data Exchange (ETDEWEB)

    Schreck, Sabine, E-mail: sabine.schreck@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials, Association KIT-EURATOM, P.O. Box 3640, D-76021 Karlsruhe (Germany); Aiello, Gaetano; Meier, Andreas; Strauss, Dirk [Karlsruhe Institute of Technology, Institute for Applied Materials, Association KIT-EURATOM, P.O. Box 3640, D-76021 Karlsruhe (Germany); Ikeda, Ryosuke; Oda, Yasuhisa; Sakamoto, Keishi; Takahashi, Koji [Japan Atomic Energy Agency (JAEA), Plasma Heating Technology Group, 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Scherer, Theo [Karlsruhe Institute of Technology, Institute for Applied Materials, Association KIT-EURATOM, P.O. Box 3640, D-76021 Karlsruhe (Germany)

    2015-10-15

    Highlights: • The diamond window prototype shows a very good transmission capability during high power RF experiments. • An ad-hoc qualification programme for the diamond torus window is being developed (contract between KIT and F4E). • The window design has been updated focused on its mechanical integrity and manufacturing aspects. - Abstract: The diamond window assembly is part of the ITER primary vacuum boundary and acts as the first tritium barrier and therefore it is classified as Safety/Protection Important Component (SIC/PIC). It consists of an ultra-low loss CVD diamond disk mounted in a system of metallic parts (copper/steel) and has to fulfil adequate transmission capability for high power mm-waves. High power RF experiments with a 1st window prototype had shown parasitic heating due to small gaps in the housing. After a design optimization directed to the mm-wave properties, the parasitic excitations of oscillations have been avoided in a 2nd prototype. This one is equipped with inserted waveguide structures, which cover gaps in the metallic structure of the window housing. From high power RF-measurements with a 0.86 MW/100 s pulse a loss tangent of 7.1 × 10{sup −6} could be estimated, corresponding to an increase of temperature of only 120 mK between inlet and outlet of the cooling system. The diamond window assemblies cannot be entirely covered by codes and standards. To comply with the French safety regulations, instead an ad-hoc qualification programme is required, being developed in the framework of a contract between KIT and F4E. A new prototype (3rd) will be built, which is designed to fit to the single HELICOFLEX sealed waveguide structures of the ex-vessel mm-system of the EC upper launcher (UL). The testing programme ranges from mechanical to vacuum tests up to dielectric loss measurements at low and high power. A clear definition of the testing requirements and of the acceptance criteria is necessary as well as a complete

  8. A survey and taxonomy of distributed certificate authorities in mobile ad hoc networks

    Directory of Open Access Journals (Sweden)

    Jabbehdari Sam

    2011-01-01

    Full Text Available Abstract Certificate authorities (CAs are the main components of PKI that enable us for providing basic security services in wired networks and Internet. But, we cannot use centralized CAs, in mobile ad hoc networks (MANETs. So, many efforts have been made to adapt CA to the special characteristics of MANETs and new concepts such as distributed CAs (DCAs have been proposed that distribute the functionality of CA between MANET nodes. In this article, we study various proposed DCA schemes for MANET and then classify these schemes according to their internal structures and techniques. Finally, we propose the characteristics of an ideal DCA system that can be used to verify the completeness of any DCA scheme. This classification and taxonomy identify the weakness and constraints of each scheme, and are very important for designing more secure, scalable, and high performance DCA systems for MANETs and other networks.

  9. Further Development of Synchronous Array Method for Ad Hoc Wireless Networks

    Directory of Open Access Journals (Sweden)

    Yingbo Hua

    2008-09-01

    Full Text Available A further development of the synchronous array method (SAM as a medium access control scheme for large-scale ad hoc wireless networks is presented. Under SAM, all transmissions of data packets between adjacent nodes are synchronized on a frame-by-frame basis, and the spacing between concurrent cochannel transmissions of data packets is properly controlled. An opportunistic SAM (O-SAM is presented which allows concurrent cochannel transmissions to be locally adaptive to channel gain variations. A distributed SAM (D-SAM is discussed that schedules all concurrent cochannel transmissions in a distributed fashion. For networks of low mobility, the control overhead required by SAM can be made much smaller than the payload. By analysis and simulation, the intranetwork throughput of O-SAM and D-SAM is evaluated. The effects of traffic load and multiple antennas on the intranetwork throughput are studied. The throughput of ALOHA is also analyzed and compared with that of O-SAM and D-SAM. By a distance-weighted throughput, a comparison of long distance transmission versus short distance transmission is also presented. The study of D-SAM reveals an important insight into the MSH-DSCH protocol adopted in IEEE 802.16 standards.

  10. Group Centric Networking: Large Scale Over the Air Testing of Group Centric Networking

    Science.gov (United States)

    2016-11-01

    Large Scale Over-the-Air Testing of Group Centric Networking Logan Mercer, Greg Kuperman, Andrew Hunter, Brian Proulx MIT Lincoln Laboratory...performance of Group Centric Networking (GCN), a networking protocol developed for robust and scalable communications in lossy networks where users are...devices, and the ad-hoc nature of the network . Group Centric Networking (GCN) is a proposed networking protocol that addresses challenges specific to

  11. A cane reduces loss of balance in patients with peripheral neuropathy: results from a challenging unipedal balance test.

    Science.gov (United States)

    Ashton-Miller, J A; Yeh, M W; Richardson, J K; Galloway, T

    1996-05-01

    To test the hypothesis that use of a cane in the nondominant hand during challenging balance tasks would significantly decrease loss of balance in patients with peripheral neuropathy while transferring from bipedal to unipedal stance on an unsteady surface. Nonrandomized control study. Tertiary-care institution. Eight consecutive patients with peripheral neuropathy (PN) and eight age- and gender-matched controls (C) with a mean (SD) age of 65 (8.2) years. Subjects were asked to transfer their weight onto their right foot, despite a rapid +/- 2 degrees or +/- 4 degrees frontal plane tilt of the support surface at 70% of weight transfer, and balance unipedally for at least 3 seconds. The efficacy of their weight transfer was evaluated over 112 consecutive randomized and blocked trials by calculating loss of balance as failure rates (%FR) with and without visual feedback, and with and without use of a cane in the nondominant (left) hand. Results were analyzed using a 2 x 2 x 2 x 2 x 2 repeated-measures analysis of variance (rm-ANOVA) and post hoc t tests. The rm-ANOVA showed that the FR of the PN subjects (47.6% [18.1%]) was significantly higher than C (29.2% [15.2%], p = .036). Removing visual feedback, simulating the dark of night, increased the FR fourfold (p = .000). Use of a cane in the contralateral nondominant hand significantly reduced the FR (p = .000), particularly in the PN group (cane x disease interaction: p = .055). Post hoc t tests showed that with or without visual feedback, the cane reduced the FR of the PN group fourfold and enabled them to perform more reliably than matched controls not using a cane (p = .011). An inversion perturbation resulted in a higher FR than an eversion perturbation (p = .007). The PN group employed larger mean peak cane forces (21.9% BW) than C (13.6% BW) in restoring their balance (p = .000). Use of a cane by PN patients significantly reduced their risk of losing balance on unstable surfaces, especially under low

  12. A Simulation Study: The Impact of Random and Realistic Mobility Models on the Performance of Bypass-AODV in Ad Hoc Wireless Networks

    Directory of Open Access Journals (Sweden)

    Baroudi Uthman

    2010-01-01

    Full Text Available To bring VANET into reality, it is crucial to devise routing protocols that can exploit the inherited characteristics of VANET environment to enhance the performance of the running applications. Previous studies have shown that a certain routing protocol behaves differently under different presumed mobility patterns. Bypass-AODV is a new optimization of the AODV routing protocol for mobile ad-hoc networks. It is proposed as a local recovery mechanism to enhance the performance of the AODV routing protocol. It shows outstanding performance under the Random Waypoint mobility model compared with AODV. However, Random Waypoint is a simple model that may be applicable to some scenarios but it is not sufficient to capture some important mobility characteristics of scenarios where VANETs are deployed. In this paper, we will investigate the performance of Bypass-AODV under a wide range of mobility models including other random mobility models, group mobility models, and vehicular mobility models. Simulation results show an interesting feature that is the insensitivity of Bypass-AODV to the selected random mobility model, and it has a clear performance improvement compared to AODV. For group mobility model, both protocols show a comparable performance, but for vehicular mobility models, Bypass-AODV suffers from performance degradation in high-speed conditions.

  13. Medium Access Control Protocols for Cognitive Radio Ad Hoc Networks: A Survey

    Directory of Open Access Journals (Sweden)

    Mahdi Zareei

    2017-09-01

    Full Text Available New wireless network paradigms will demand higher spectrum use and availability to cope with emerging data-hungry devices. Traditional static spectrum allocation policies cause spectrum scarcity, and new paradigms such as Cognitive Radio (CR and new protocols and techniques need to be developed in order to have efficient spectrum usage. Medium Access Control (MAC protocols are accountable for recognizing free spectrum, scheduling available resources and coordinating the coexistence of heterogeneous systems and users. This paper provides an ample review of the state-of-the-art MAC protocols, which mainly focuses on Cognitive Radio Ad Hoc Networks (CRAHN. First, a description of the cognitive radio fundamental functions is presented. Next, MAC protocols are divided into three groups, which are based on their channel access mechanism, namely time-slotted protocol, random access protocol and hybrid protocol. In each group, a detailed and comprehensive explanation of the latest MAC protocols is presented, as well as the pros and cons of each protocol. A discussion on future challenges for CRAHN MAC protocols is included with a comparison of the protocols from a functional perspective.

  14. Unconscious fearful priming followed by a psychosocial stress test results in higher cortisol levels.

    Science.gov (United States)

    Hänsel, Alexander; von Känel, Roland

    2013-10-01

    Human perception of stress includes an automatic pathway that processes subliminal presented stimuli below the threshold of conscious awareness. Subliminal stimuli can therefore activate the physiologic stress system. Unconscious emotional signals were shown to significantly moderate reactions and responses to subsequent stimuli, an effect called 'priming'. We hypothesized that subliminal presentation of a fearful signal during the Stroop task compared with an emotionally neutral one will prime stress reactivity in a subsequently applied psychosocial stress task, thereby yielding a significant increase in salivary cortisol. Half of 36 participants were repeatedly presented either a fearful face or a neutral one. After this, all underwent a psychosocial stress task. The fearful group showed a significant increase in cortisol levels (p = 0.022). This change was not affected by sex, age and body mass index, and it also did not change when taking resting cortisol levels into account. Post-hoc analyses showed that the increase in cortisol in the fearful group started immediately after the psychosocial stress test. Hence, subliminal exposure to a fearful signal in combination with the Stroop and followed by a psychosocial stress test leads to an increase in stress reactivity. Copyright © 2012 John Wiley & Sons, Ltd.

  15. PSO-Optimized Hopfield Neural Network-Based Multipath Routing for Mobile Ad-hoc Networks

    Directory of Open Access Journals (Sweden)

    Mansour Sheikhan

    2012-06-01

    Full Text Available Mobile ad-hoc network (MANET is a dynamic collection of mobile computers without the need for any existing infrastructure. Nodes in a MANET act as hosts and routers. Designing of robust routing algorithms for MANETs is a challenging task. Disjoint multipath routing protocols address this problem and increase the reliability, security and lifetime of network. However, selecting an optimal multipath is an NP-complete problem. In this paper, Hopfield neural network (HNN which its parameters are optimized by particle swarm optimization (PSO algorithm is proposed as multipath routing algorithm. Link expiration time (LET between each two nodes is used as the link reliability estimation metric. This approach can find either node-disjoint or link-disjoint paths in singlephase route discovery. Simulation results confirm that PSO-HNN routing algorithm has better performance as compared to backup path set selection algorithm (BPSA in terms of the path set reliability and number of paths in the set.

  16. Neuroprotection as initial therapy in acute stroke. Third Report of an Ad Hoc Consensus Group Meeting. The European Ad Hoc Consensus Group.

    Science.gov (United States)

    1998-01-01

    Although a considerable body of scientific data is now available on neuroprotection in acute ischaemic stroke, this field is not yet established in clinical practice. At its third meeting, the European Ad Hoc Consensus Group considered the potential for neuroprotection in acute stroke and the practical problems attendant on the existence of a very limited therapeutic window before irreversible brain damage occurs, and came to the following conclusions. NEUROPROTECTANTS IN CLINICAL DEVELOPMENT: Convincing clinical evidence for an efficacious neuroprotective treatment in acute stroke is still required. Caution should be exercised in interpreting and extrapolating experimental results to stroke patients, who are a very heterogeneous group. The limitations of the time windows and the outcome measures chosen in trials of acute stroke therapy have an important influence on the results. The overall distribution of functional outcomes provides more statistical information than the proportion above a threshold outcome value. Neurological outcome should also be assessed. Neuroprotectants should not be tested clinically in phase II or phase III trials in a time window that exceeds those determined in experimental studies. The harmful effects of a drug in humans may override its neuroprotective potential determined in animals. Agents that act at several different levels in the ischaemic cascade may be more effective than those with a single mechanism of action. CURRENT IN-HOSPITAL MANAGEMENT OF ACUTE STROKE: The four major physiological variables that must be monitored and managed are blood pressure, arterial blood gas levels, body temperature, and glycaemia. The effects of controlling these physiological variables have not been studied in prospective trials, though they may all contribute to the outcome of acute ischaemic stroke and affect the duration of the therapeutic window. Optimal physiological parameters are inherently neuroprotective. Trials of new agents for the

  17. A CONTEXT AWARE BASED PRE-HANDOFF SUPPORT APPROACH TO PROVIDE OPTIMAL QOS FOR STREAMING APPLICATIONS OVER VEHICULAR AD HOC NETWORKS – HOSA

    Directory of Open Access Journals (Sweden)

    K. RAMESH BABU

    2015-06-01

    Full Text Available Large variations in network Quality of Service (QoS such as bandwidth, latency, jitter, and reliability may occur during media transfer over vehicular ad hoc networks (VANET. Usage of VANET over mobile and wireless computing applications experience “bursty” QoS behavior during the execution over distributed network scenarios. Applications such as streaming media services need to adapt their functionalities to any change in network status. Moreover, an enhanced software platform is necessary to provide adaptive network management services to upper software components. HOSA, a handoff service broker based architecture for QoS adaptation over VANET supports in providing awareness. HOSA is structured as a middleware platform both to provide QoS awareness to streaming applications as well to manage dynamic ad hoc network resources with support over handoff in an adaptive fashion. HOSA is well analyzed over routing schemes such as TIBSCRPH, SIP and ABSRP where performance of HOSA was measured using throughput, traffic intensity and end to end delay. HOSA has been analyzed using JXTA development toolkit over C++ implemented classes to demonstrate its performance over varying node mobility established using vehicular mobility based conference application.

  18. Protective effect of yerba mate intake on the cardiovascular system: a post hoc analysis study in postmenopausal women.

    Science.gov (United States)

    da Veiga, D T A; Bringhenti, R; Copes, R; Tatsch, E; Moresco, R N; Comim, F V; Premaor, M O

    2018-01-01

    The prevalence of cardiovascular and metabolic diseases is increased in postmenopausal women, which contributes to the burden of illnesses in this period of life. Yerba mate (Ilex paraguariensis) is a native bush from Southern South America. Its leaves are rich in phenolic components, which may have antioxidant, vasodilating, hypocholesterolemic, and hypoglycemic proprieties. This post hoc analysis of the case-control study nested in the Obesity and Bone Fracture Cohort evaluated the consumption of yerba mate and the prevalence of hypertension, dyslipidemia, and coronary diseases in postmenopausal women. Ninety-five postmenopausal women were included in this analysis. A questionnaire was applied to evaluate the risk factors and diagnosis of cardiovascular diseases and consumption of yerba mate infusion. Student's t-test and chi-square test were used to assess significant differences between groups. The group that consumed more than 1 L/day of mate infusion had significantly fewer diagnoses of coronary disease, dyslipidemia, and hypertension (P<0.049, P<0.048, and P<0.016, respectively). Furthermore, the serum levels of glucose were lower in the group with a higher consumption of yerba mate infusion (P<0.013). The serum levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides were similar between the groups. This pragmatic study points out the benefits of yerba mate consumption for the cardiovascular and metabolic systems. The ingestion of more than 1 L/day of mate infusion was associated with fewer self-reported cardiovascular diseases and lower serum levels of glucose. Longitudinal studies are needed to evaluate the association between yerba mate infusion and reduction of cardiovascular diseases in postmenopausal women.

  19. On using multiple routing metrics with destination sequenced distance vector protocol for MultiHop wireless ad hoc networks

    Science.gov (United States)

    Mehic, M.; Fazio, P.; Voznak, M.; Partila, P.; Komosny, D.; Tovarek, J.; Chmelikova, Z.

    2016-05-01

    A mobile ad hoc network is a collection of mobile nodes which communicate without a fixed backbone or centralized infrastructure. Due to the frequent mobility of nodes, routes connecting two distant nodes may change. Therefore, it is not possible to establish a priori fixed paths for message delivery through the network. Because of its importance, routing is the most studied problem in mobile ad hoc networks. In addition, if the Quality of Service (QoS) is demanded, one must guarantee the QoS not only over a single hop but over an entire wireless multi-hop path which may not be a trivial task. In turns, this requires the propagation of QoS information within the network. The key to the support of QoS reporting is QoS routing, which provides path QoS information at each source. To support QoS for real-time traffic one needs to know not only minimum delay on the path to the destination but also the bandwidth available on it. Therefore, throughput, end-to-end delay, and routing overhead are traditional performance metrics used to evaluate the performance of routing protocol. To obtain additional information about the link, most of quality-link metrics are based on calculation of the lost probabilities of links by broadcasting probe packets. In this paper, we address the problem of including multiple routing metrics in existing routing packets that are broadcasted through the network. We evaluate the efficiency of such approach with modified version of DSDV routing protocols in ns-3 simulator.

  20. Anti-Vascular Endothelial Growth Factor Comparative Effectiveness Trial for Diabetic Macular Edema: Additional Efficacy Post Hoc Analyses of a Randomized Clinical Trial.

    Science.gov (United States)

    Jampol, Lee M; Glassman, Adam R; Bressler, Neil M; Wells, John A; Ayala, Allison R

    2016-12-01

    Post hoc analyses from the Diabetic Retinopathy Clinical Research Network randomized clinical trial comparing aflibercept, bevacizumab, and ranibizumab for diabetic macular edema (DME) might influence interpretation of study results. To provide additional outcomes comparing 3 anti-vascular endothelial growth factor (VEGF) agents for DME. Post hoc analyses performed from May 3, 2016, to June 21, 2016, of a randomized clinical trial performed from August 22, 2012, to September 23, 2015, of 660 participants comparing 3 anti-VEGF treatments in eyes with center-involved DME causing vision impairment. Randomization to intravitreous aflibercept (2.0 mg), bevacizumab (1.25 mg), or ranibizumab (0.3 mg) administered up to monthly based on a structured retreatment regimen. Focal/grid laser treatment was added after 6 months for the treatment of persistent DME. Change in visual acuity (VA) area under the curve and change in central subfield thickness (CST) within subgroups based on whether an eye received laser treatment for DME during the study. Post hoc analyses were performed for 660 participants (mean [SD] age, 61 [10] years; 47% female, 65% white, 16% black or African American, 16% Hispanic, and 3% other). For eyes with an initial VA of 20/50 or worse, VA improvement was greater with aflibercept than the other agents at 1 year but superior only to bevacizumab at 2 years. Mean (SD) letter change in VA over 2 years (area under curve) was greater with aflibercept (+17.1 [9.7]) than with bevacizumab (+12.1 [9.4]; 95% CI, +1.6 to +7.3; P grid laser treatment was performed for DME, the only participants to have a substantial reduction in mean CST between 1 and 2 years were those with a baseline VA of 20/50 or worse receiving bevacizumab and laser treatment (mean [SD], -55 [108] µm; 95% CI, -82 to -28 µm; P grid laser treatment, ceiling and floor effects, or both may account for mean thickness reductions noted only in bevacizumab-treated eyes between 1 and 2 years

  1. To Show or Not to Show: The Effects of Item Stems and Answer Options on Performance on a Multiple-Choice Listening Comprehension Test

    Science.gov (United States)

    Yanagawa, Kozo; Green, Anthony

    2008-01-01

    The purpose of this study is to examine whether the choice between three multiple-choice listening comprehension test formats results in any difference in listening comprehension test performance. The three formats entail (a) allowing test takers to preview both the question stem and answer options prior to listening; (b) allowing test takers to…

  2. Securing ad hoc wireless sensor networks under Byzantine attacks by implementing non-cryptographic method

    Directory of Open Access Journals (Sweden)

    Shabir Ahmad Sofi

    2017-05-01

    Full Text Available Ad Hoc wireless sensor network (WSN is a collection of nodes that do not need to rely on predefined infrastructure to keep the network connected. The level of security and performance are always somehow related to each other, therefore due to limited resources in WSN, cryptographic methods for securing the network against attacks is not feasible. Byzantine attacks disrupt the communication between nodes in the network without regard to its own resource consumption. This paper discusses the performance of cluster based WSN comparing LEACH with Advanced node based clusters under byzantine attacks. This paper also proposes an algorithm for detection and isolation of the compromised nodes to mitigate the attacks by non-cryptographic means. The throughput increases after using the algorithm for isolation of the malicious nodes, 33% in case of Gray Hole attack and 62% in case of Black Hole attack.

  3. Cyclic fatigue resistance tests of Nickel-Titanium rotary files using simulated canal and weight loading conditions

    Directory of Open Access Journals (Sweden)

    Ok-In Cho

    2013-02-01

    Full Text Available Objectives This study compared the cyclic fatigue resistance of nickel-titanium (NiTi files obtained in a conventional test using a simulated canal with a newly developed method that allows the application of constant fatigue load conditions. Materials and Methods ProFile and K3 files of #25/.06, #30/.06, and #40/.04 were selected. Two types of testing devices were built to test their fatigue performance. The first (conventional device prescribed curvature inside a simulated canal (C-test, the second new device exerted a constant load (L-test whilst allowing any resulting curvature. Ten new instruments of each size and brand were tested with each device. The files were rotated until fracture and the number of cycles to failure (NCF was determined. The NCF were subjected to one-way ANOVA and Duncan's post-hoc test for each method. Spearman's rank correlation coefficient was computed to examine any association between methods. Results Spearman's rank correlation coefficient (ρ = -0.905 showed a significant negative correlation between methods. Groups with significant difference after the L-test divided into 4 clusters, whilst the C-test gave just 2 clusters. From the L-test, considering the negative correlation of NCF, K3 gave a significantly lower fatigue resistance than ProFile as in the C-test. K3 #30/.06 showed a lower fatigue resistance than K3 #25/.06, which was not found by the C-test. Variation in fatigue test methodology resulted in different cyclic fatigue resistance rankings for various NiTi files. Conclusions The new methodology standardized the load during fatigue testing, allowing determination fatigue behavior under constant load conditions.

  4. Routine training is not enough: structured training in family planning and abortion improves residents' competency scores and intentions to provide abortion after graduation more than ad hoc training.

    Science.gov (United States)

    Macisaac, Laura; Vickery, Zevidah

    2012-03-01

    Abortion provision remains threatened by the paucity of physicians trained to provide them. Lack of training during residency has been cited by obstetrician and gynecologist (ob-gyn) physicians as a reason for not including abortion in their practice. We administered surveys on interest, competency and intention to provide abortions to two groups of ob-gyn residents: one experiencing a new comprehensive and structured family planning rotation, and another group at our affiliate hospital's residency program receiving "ad hoc" training during their routine gynecology rotations. Surveys were anonymous and blinded to investigator. The structured family planning rotation group compared to the ad hoc group reported significantly increased competency score using a Likert scale in manual vacuum aspiration (MVA) (4.5 vs. 1; p=.003) and had a higher proportion reporting intent to provide office MVA postresidency (100% vs. 39%; p=.01) and being trained to 22.5 weeks' vs. 12 weeks' gestation (p=.005). In bivariate analysis, competency in MVA was associated with higher intentions to provide MVA after residency (p=.007). A structured rotation in family planning and abortion for obstetrics/gynecology residents results in increases in competency and intentions to provide abortion, and an association between the two. In-hospital structured training proved to be superior to ad hoc training in our affiliate institution in improving competency and intention to provide abortion after residency. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Resistivity tomography of Pointe du Hoc cliffs for stability assessment

    Science.gov (United States)

    Udphuay, S.; Everett, M. E.; Warden, R.

    2008-12-01

    Pointe du Hoc WWII battlefield overlooking the English Channel in western Normandy, France, is an important cultural resource, being an integral component of the June 6 1944 D-Day invasion. Two major buildings, the forward observation post (OP) and Col. Rudder's command post (RCP), are now perched perilously close to the cliff's edge owing to six decades of cliff retreat. Geophysical surveys were carried out in March 2008 to investigate the risk of cliff failure and to inform possible geotechnical remediation strategies with a final goal toward re-opening the observation post that is now closed to visitors. The geophysical surveying is accomplished by high-resolution resistivity tomography, conducted in extreme topography and in the midst of dense cultural clutter. The results of the OP tomography indicate that the highest mass movement hazard is associated with the marine caverns at the base of the cliff at the point of strongest wave attack. These caverns occupy the future site of a sea arch which will threaten the OP building. There is a high probability of a soil wedge failure on the east facing cliff edge close to the OP building. Such a failure could damage or destroy the building. The possibility of a sudden catastrophic failure along any one of these fractures cannot be ruled out. The greatest risk at the RCP site, which is under less immediate threat, is associated with soil wedge failures at the top of the cliffs.

  6. A Sensitive Secondary Users Selection Algorithm for Cognitive Radio Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Aohan Li

    2016-03-01

    Full Text Available Secondary Users (SUs are allowed to use the temporarily unused licensed spectrum without disturbing Primary Users (PUs in Cognitive Radio Ad Hoc Networks (CRAHNs. Existing architectures for CRAHNs impose energy-consuming Cognitive Radios (CRs on SUs. However, the advanced CRs will increase energy cost for their cognitive functionalities, which is undesirable for the battery powered devices. A new architecture referred to as spectral Requirement-based CRAHN (RCRAHN is proposed to enhance energy efficiency for CRAHNs in this paper. In RCRAHNs, only parts of SUs are equipped with CRs. SUs equipped with CRs are referred to as Cognitive Radio Users (CRUs. To further enhance energy efficiency of CRAHNs, we aim to select minimum CRUs to sense available spectrum. A non-linear programming problem is mathematically formulated under the constraints of energy efficiency and real-time. Considering the NP-hardness of the problem, a framework of a heuristic algorithm referred to as Sensitive Secondary Users Selection (SSUS was designed to compute the near-optimal solutions. The simulation results demonstrate that SSUS not only improves the energy efficiency, but also achieves satisfied performances in end-to-end delay and communication reliability.

  7. A Sensitive Secondary Users Selection Algorithm for Cognitive Radio Ad Hoc Networks.

    Science.gov (United States)

    Li, Aohan; Han, Guangjie; Wan, Liangtian; Shu, Lei

    2016-03-26

    Secondary Users (SUs) are allowed to use the temporarily unused licensed spectrum without disturbing Primary Users (PUs) in Cognitive Radio Ad Hoc Networks (CRAHNs). Existing architectures for CRAHNs impose energy-consuming Cognitive Radios (CRs) on SUs. However, the advanced CRs will increase energy cost for their cognitive functionalities, which is undesirable for the battery powered devices. A new architecture referred to as spectral Requirement-based CRAHN (RCRAHN) is proposed to enhance energy efficiency for CRAHNs in this paper. In RCRAHNs, only parts of SUs are equipped with CRs. SUs equipped with CRs are referred to as Cognitive Radio Users (CRUs). To further enhance energy efficiency of CRAHNs, we aim to select minimum CRUs to sense available spectrum. A non-linear programming problem is mathematically formulated under the constraints of energy efficiency and real-time. Considering the NP-hardness of the problem, a framework of a heuristic algorithm referred to as Sensitive Secondary Users Selection (SSUS) was designed to compute the near-optimal solutions. The simulation results demonstrate that SSUS not only improves the energy efficiency, but also achieves satisfied performances in end-to-end delay and communication reliability.

  8. Standard software for automated testing of infrared imagers, IRWindows, in practical applications

    Science.gov (United States)

    Irwin, Alan; Nicklin, Robert L.

    1998-08-01

    In the past, ad-hoc and manual testing of infrared images hasn't been a deterrent to the characterization of these systems due to the low volume of production and high ratio of skilled personnel to the quantity of units under test. However, with higher volume production, increasing numbers of development labs in emerging markets, and the push towards less expensive, faster development cycles, there is a strong need for standardized testing that is quickly configurable by test engineers, which can be run by less experienced test technicians, and which produce repeatable, accurate results. The IRWindowsTM system addresses these needs using a standard computing platform and existing automated IR test equipment. This paper looks at the general capabilities of the IRWindowsTM system, and then examines the specific results from its application in the PalmIR and Automotive IR production environments.

  9. Are we drawing the right conclusions from randomised placebo-controlled trials? A post-hoc analysis of data from a randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Bone Kerry M

    2009-06-01

    Full Text Available Abstract Background Assumptions underlying placebo controlled trials include that the placebo effect impacts on all study arms equally, and that treatment effects are additional to the placebo effect. However, these assumptions have recently been challenged, and different mechanisms may potentially be operating in the placebo and treatment arms. The objective of the current study was to explore the nature of placebo versus pharmacological effects by comparing predictors of the placebo response with predictors of the treatment response in a randomised, placebo-controlled trial of a phytotherapeutic combination for the treatment of menopausal symptoms. A substantial placebo response was observed but no significant difference in efficacy between the two arms. Methods A post hoc analysis was conducted on data from 93 participants who completed this previously published study. Variables at baseline were investigated as potential predictors of the response on any of the endpoints of flushing, overall menopausal symptoms and depression. Focused tests were conducted using hierarchical linear regression analyses. Based on these findings, analyses were conducted for both groups separately. These findings are discussed in relation to existing literature on placebo effects. Results Distinct differences in predictors were observed between the placebo and active groups. A significant difference was found for study entry anxiety, and Greene Climacteric Scale (GCS scores, on all three endpoints. Attitude to menopause was found to differ significantly between the two groups for GCS scores. Examination of the individual arms found anxiety at study entry to predict placebo response on all three outcome measures individually. In contrast, low anxiety was significantly associated with improvement in the active treatment group. None of the variables found to predict the placebo response was relevant to the treatment arm. Conclusion This study was a post hoc analysis

  10. Sustained disease-activity-free status in patients with relapsing-remitting multiple sclerosis treated with cladribine tablets in the CLARITY study: a post-hoc and subgroup analysis

    DEFF Research Database (Denmark)

    Giovannoni, Gavin; Cook, Stuart; Rammohan, Kottil

    2011-01-01

    /kg over 96 weeks was more effective than placebo. Achieving sustained freedom from disease activity is becoming a viable treatment goal in RRMS; we therefore aimed to assess the effects of cladribine on this composite outcome measure by doing a post-hoc analysis of data from the CLARITY study....

  11. African Journal of Drug & Alcohol Studies, 15(1), 2016 Copyright ...

    African Journals Online (AJOL)

    male and 29 female inmates from Uyo prison participated in the study. Their mean age ... A post-hoc test was conducted using LSD to show multiple comparison effect. Furthermore, the t-test ...... Monitoring the brain's response to al- cohol with ...

  12. EPA Requests Nominations for Experts to Serve on the May 8-10, 2018 FIFRA SAP on Efficacy Testing of Pesticides used for Invertebrate Pests and Fire Ants

    Science.gov (United States)

    FRN requesting nominations of experts to serve as ad hoc members for the May 8-10, 2018 FIFRA SAP meeting to consider and review methods for efficacy testing of pesticides used for treatments of invertebrate pests and fire ants.

  13. Atomoxetine treatment outcomes in adolescents and young adults with attention-deficit/hyperactivity disorder: results from a post hoc, pooled analysis.

    Science.gov (United States)

    Adler, Lenard A; Wilens, Timothy; Zhang, Shuyu; Dittmann, Ralf W; D'Souza, Deborah N; Schuh, Leslie; Durell, Todd M

    2012-02-01

    Many children with attention-deficit/hyperactivity disorder (ADHD) continue to experience this disorder as adults, which may, in part, be due to the discontinuity of health care that often occurs during the transition period between late adolescence and young adulthood. Although atomoxetine is reported to be efficacious in both adolescents and young adults, no longitudinal studies have been designed to assess directly the effects of atomoxetine treatment during this transition period. As a first step, we present the results of a post hoc, pooled analysis that compared the efficacy and safety profile of atomoxetine in these 2 patient populations. The aim of the present study was to assess the efficacy and safety profile of atomoxetine treatment in adolescents and young adults with ADHD. A post hoc, pooled analysis was conducted by combining data from 6 double-blind trials (6-9 weeks in duration) that studied adolescents (12-17 years of age; atomoxetine, n = 154; placebo, n = 88; mean final dose = 1.38 mg/kg) and 3 trials (10 weeks in duration) that studied young adults (18-30 years of age; atomoxetine, n = 117; placebo, n = 125; mean final dose = 1.21 mg/kg). Efficacy measures used in these analyses were ADHD Rating Scale (ADHDRS) for adolescents, Conners' Adult ADHD Rating Scale (CAARS) for young adults, and Clinical Global Impressions-ADHD-Severity (CGI-ADHD-S) for both age groups. Treatment response was defined as ≥30% reduction from baseline in total ADHD symptom score. In adolescents (mean age, 13.4 years), atomoxetine improved ADHD significantly compared with placebo (ADHDRS total score change, -12.9 vs -7.5; P young adults (mean age, 24.7 years), atomoxetine improved ADHD significantly (CAARS total score change, -13.6 vs -7.7; P young adults (13.7% vs 4.8%, respectively; P = 0.024); in adolescents no statistically significant differences were observed in frequency of nausea between atomoxetine and placebo treatment (4.5% vs 10.2%, respectively; P = 0

  14. Perioperative hyperoxia - Long-term impact on cardiovascular complications after abdominal surgery, a post hoc analysis of the PROXI trial

    DEFF Research Database (Denmark)

    Fonnes, Siv; Gogenur, Ismail; Sondergaard, Edith Smed

    2016-01-01

    BACKGROUND: Increased long-term mortality was found in patients exposed to perioperative hyperoxia in the PROXI trial, where patients undergoing laparotomy were randomised to 80% versus 30% oxygen during and after surgery. This post hoc follow-up study assessed the impact of perioperative hyperoxia...... included myocardial infarction, other heart disease, and acute coronary syndrome or death. Data were analysed in the Cox proportional hazards model. RESULTS: The primary outcome, acute coronary syndrome, occurred in 2.5% versus 1.3% in the 80% versus 30% oxygen group; HR 2.15 (95% CI 0.96-4.84). Patients...

  15. Two-terminal reliability of a mobile ad hoc network under the asymptotic spatial distribution of the random waypoint model

    International Nuclear Information System (INIS)

    Chen, Binchao; Phillips, Aaron; Matis, Timothy I.

    2012-01-01

    The random waypoint (RWP) mobility model is frequently used in describing the movement pattern of mobile users in a mobile ad hoc network (MANET). As the asymptotic spatial distribution of nodes under a RWP model exhibits central tendency, the two-terminal reliability of the MANET is investigated as a function of the source node location. In particular, analytical expressions for one and two hop connectivities are developed as well as an efficient simulation methodology for two-terminal reliability. A study is then performed to assess the effect of nodal density and network topology on network reliability.

  16. Energy generation for an ad hoc wireless sensor network-based monitoring system using animal head movement

    DEFF Research Database (Denmark)

    S. Nadimi, Esmaeil; Blanes-Vidal, Victoria; Jørgensen, Rasmus Nyholm

    2011-01-01

    are not easily accessible. Therefore, exploring novel sources of energy generation rather than operating electronics only on limited power supplies such as batteries is a major challenge. Monitoring free-ranging animal behavior is an application in which the entities (animals) within the MANET are not readily...... that the amount of energy generated by the vertical neck–head movement of sheep during grazing can be converted to useful electrical power adequate to provide power for operation of wireless sensor nodes on a continuous basis within a MANET-based animal behavior monitoring system.......The supply of energy to electronics is an imperative constraining factor to be considered during the design process of mobile ad hoc wireless sensor networks (MANETs). This influence is especially important when the MANET is deployed unattended or the wireless modules within the MANET...

  17. Analysis of Soldier Radio Waveform Performance in Operational Test

    Science.gov (United States)

    2015-05-01

    different frequencies based on carrier, uplink/downlink, and generation. In general, 2G and 3G cellular phones operate at 850 MHz uplink, and 1,900 MHz...spectrum management that may not be operationally feasible. These issues are not unique to SRW, but rather have plagued the mobile ad-hoc network... mobile ad-hoc network (MANET), enabling communication through a self-configuring, infrastructure-less network of mobile nodes. In the SS domain, these

  18. A DNA-Inspired Encryption Methodology for Secure, Mobile Ad Hoc Networks

    Science.gov (United States)

    Shaw, Harry

    2012-01-01

    Users are pushing for greater physical mobility with their network and Internet access. Mobile ad hoc networks (MANET) can provide an efficient mobile network architecture, but security is a key concern. A figure summarizes differences in the state of network security for MANET and fixed networks. MANETs require the ability to distinguish trusted peers, and tolerate the ingress/egress of nodes on an unscheduled basis. Because the networks by their very nature are mobile and self-organizing, use of a Public Key Infra structure (PKI), X.509 certificates, RSA, and nonce ex changes becomes problematic if the ideal of MANET is to be achieved. Molecular biology models such as DNA evolution can provide a basis for a proprietary security architecture that achieves high degrees of diffusion and confusion, and resistance to cryptanalysis. A proprietary encryption mechanism was developed that uses the principles of DNA replication and steganography (hidden word cryptography) for confidentiality and authentication. The foundation of the approach includes organization of coded words and messages using base pairs organized into genes, an expandable genome consisting of DNA-based chromosome keys, and a DNA-based message encoding, replication, and evolution and fitness. In evolutionary computing, a fitness algorithm determines whether candidate solutions, in this case encrypted messages, are sufficiently encrypted to be transmitted. The technology provides a mechanism for confidential electronic traffic over a MANET without a PKI for authenticating users.

  19. Patterns of HIV testing practices among young gay and bisexual men living in Scotland: a qualitative study.

    Science.gov (United States)

    Boydell, Nicola; Buston, Katie; McDaid, Lisa Margaret

    2017-08-17

    Increasing overall rates, and frequency, of HIV testing in populations at risk is a key public health objective and a critical dimension of HIV prevention efforts. In the UK, men who have sex with men (MSM) remain one of the communities most at risk of HIV and, within this, young gay men are a key risk group. Understanding HIV testing practices is important in the development of interventions to promote testing among young gay and bisexual men. Qualitative interviews were conducted with thirty young gay and bisexual men (aged 18-29) in Scotland. Thematic analysis of men's accounts of their approach to HIV testing identified three overarching patterns of testing: 'habitual', 'reactive' and ' ad hoc'. This qualitative study, the first to explore patterns of HIV testing practices among young gay and bisexual men in the UK, contributes novel findings around the role of social support and 'community' in shaping young men's approaches to HIV testing. The findings suggest that social support can play an important role in encouraging and facilitating HIV testing among young gay men, however, social norms of non-testing also have the potential to act as a barrier to development of a regular routine. Men with habitual testing practices framed HIV testing as both a personal and 'community' responsibility, and more effective than testing in response to risk events or emergent symptoms. Men who reported reactive testing practices described testing for HIV primarily in response to perceived exposure to sexual risk, along with 'transitional moments' such as starting, ending or changes to a relationship. Among young men who reported testing on an ad hoc basis, inconvenience and disruptions to HIV testing practices, particularly where men lacked social support, acted as a barrier to developing a routine of regular testing. Our findings suggest that interventions which seek to increase rates of HIV testing and testing frequency among young gay and bisexual men should include a

  20. Relationship between intraoperative regional cerebral oxygen saturation trends and cognitive decline after total knee replacement: a post-hoc analysis.

    Science.gov (United States)

    Salazar, Fátima; Doñate, Marta; Boget, Teresa; Bogdanovich, Ana; Basora, Misericordia; Torres, Ferran; Gracia, Isabel; Fàbregas, Neus

    2014-01-01

    Bilateral regional brain oxygen saturation (rSO2) trends, reflecting intraoperative brain oxygen imbalance, could warn of brain dysfunction. Various types of cognitive impairment, such as memory decline, alterations in executive function or subjective complaints, have been described three months after surgery. Our aim was to explore the potential utility of rSO2 values as a warning sign for the development of different types of decline in postoperative psychological function. Observational post-hoc analysis of data for the patient sample (n = 125) of a previously conducted clinical trial in patients over the age of 65 years undergoing total knee replacement under spinal anesthesia. Demographic, hemodynamic and bilateral rSO2 intraoperative values were recorded. An absolute rSO2 value of 20% or >25% below baseline were chosen as relevant cutoffs. Composite function test scores were created from baseline to three months for each patient and adjusted for the mean (SD) score changes for a control group (n = 55). Tests were used to assess visual-motor coordination and executive function (VM-EF) (Wechsler Digit Symbol-Coding and Visual Reproduction, Trail Making Test) and memory (Auditory Verbal Learning, Wechsler Memory Scale); scales were used to assess psychological symptoms. We observed no differences in baseline rSO2 values; rSO2 decreased significantly in all patients during surgery (P Left and right rSO2 values were asymmetric in patients who had memory decline (mean [SD] left-right ratio of 95.03 [8.51] vs 101.29 [6.7] for patients with no changes, P = 0.0012). The mean right-left difference in rSO2 was also significant in these patients (-2.87% [4.73%], lower on the right, P = 0.0034). Detection of a trend to asymmetry in rSO2 values can warn of possible postoperative onset of memory decline. Psychological symptoms and memory decline were common three months after knee replacement in our patients over the age of 65 years.