This document summarizes research on limiting the spread of rumors in social networks. It discusses two models for how influence spreads: deterministic one activate many (DOAM) and opportunistic one activate one (OPOAO). It defines the least cost rumor blocking problem (LCRB) as finding the minimum number of "protectors" needed to limit rumor influence. For DOAM, it presents a set cover based greedy algorithm and proves it provides a polynomial time approximation. Experimental results on two networks show it performs well. For OPOAO, it formulates LCRB as protecting a fraction of bridge ends and proves the greedy approach is optimal due to submodularity of the influence function.
Properties and Impact of Vicinity in Mobile Opportunistic Networkstiphainepn
This document summarizes three contributions related to modeling vicinity dynamics in opportunistic mobile networks:
1. It analyzes vicinity properties like k-contact and k-intercontact intervals to show transmission opportunities beyond direct contact. Using a k-vicinity of 3-4 hops captures most opportunities.
2. It models pairwise vicinity motion as a Markov chain and identifies three main patterns - birth, death, and sequential movements. Most observed movements fall into death and sequential categories.
3. It proposes a vicinity timeline generator called TiGeR that produces synthetic vicinity behaviors matching real datasets. It also presents a prediction method based on modeling synchronous vicinity motion as a Markovian heuristic to forecast vicinity over time.
In this paper we study of the MOR cryptosystem using camina group. We show that using the automorphism of the camina group one can build a secure MOR cryptosystem.
The Hidden Geometry of Multiplex Networks @ Next Generation Network Analytics Kolja Kleineberg
The document summarizes research on the hidden geometry of multiplex networks. It finds that real-world multiplex networks often have correlated geometric properties between network layers, with nodes maintaining similar radial and angular coordinates. This has implications like communities of nodes being similar across layers and hyperbolic distance in one layer predicting connections in another. A geometric multiplex model is introduced to generate realistic multiplex networks with tunable geometric correlations between layers.
ICPSR - Complex Systems Models in the Social Sciences - Lab Session 2 - Profe...Daniel Katz
This document provides an overview of the forest fire model simulation. It discusses:
(1) The setup procedure which initializes the world with green "patches" representing trees, at a random density.
(2) The "ignite" procedure which sets a random patch on fire to start the simulation.
(3) The fire then spreads deterministically from burning trees to neighboring trees based on the code rules, while the placement of trees was random.
The document explores modifying aspects of the model like changing the color of trees or direction of fire spread. It also discusses representing the dependencies in the code and analyzing the deterministic and random elements conceptually.
A novel cluster based wormhole avoidance algorithm for mobile adhoc networkscsandit
A severe type of network layer security attack called Wormhole attack can occur in MANET,
during which a malicious node captures packets from one location in the network, and tunnels
them to another colluding malicious node at a distant point, which replays them locally. This
paper presents a hierarchical cluster based Wormhole attack avoidance technique to avoid such
scenario. The concept of hierarchical clustering with a novel hierarchical 32-bit node
addressing scheme is used for avoiding the attacking path during the route discovery phase of
the DSR protocol, which is considered as the under lying routing protocol. Pinpointing the
location of the Wormhole nodes in the case of exposed attack is also given by using this method.
The document analyzes the wormhole attack in wireless ad hoc networks. It shows that a strategic placement of the wormhole can disrupt on average 32% of communications across the network. It also analyzes a more severe attack with multiple attackers and gives an upper bound of (1-1/n) of disrupted communications for n attackers. Finally, it proposes a new routing protocol to counter wormhole and other attacks by allowing routing as long as there is a non-faulty path between source and destination.
Geometric correlations in multiplexes and how they make them more robustKolja Kleineberg
This document discusses research on the structure and dynamics of multiplex networks. It begins by introducing the concept of multiplex networks, which have the same nodes existing across different network layers. It then discusses how degree correlations and geometric correlations between the positions of nodes in the hidden metric spaces underlying different network layers have been found in real multiplex systems. The document explores how these geometric correlations allow for applications like better identifying communities of nodes, improved link prediction between layers, and more efficient navigation across the network layers.
This document presents two papers on analyzing bursty topics from microblogs and modeling latent topic transitions in social media. The first paper proposes using temporal information from microblog posts and users' interests to detect bursty topics. The second paper introduces TM-LDA, a topic model that captures latent topic transitions over time in sequentially posted documents and efficiently updates online. Both papers aim to model topics in a temporally-aware manner from streaming social media data.
Properties and Impact of Vicinity in Mobile Opportunistic Networkstiphainepn
This document summarizes three contributions related to modeling vicinity dynamics in opportunistic mobile networks:
1. It analyzes vicinity properties like k-contact and k-intercontact intervals to show transmission opportunities beyond direct contact. Using a k-vicinity of 3-4 hops captures most opportunities.
2. It models pairwise vicinity motion as a Markov chain and identifies three main patterns - birth, death, and sequential movements. Most observed movements fall into death and sequential categories.
3. It proposes a vicinity timeline generator called TiGeR that produces synthetic vicinity behaviors matching real datasets. It also presents a prediction method based on modeling synchronous vicinity motion as a Markovian heuristic to forecast vicinity over time.
In this paper we study of the MOR cryptosystem using camina group. We show that using the automorphism of the camina group one can build a secure MOR cryptosystem.
The Hidden Geometry of Multiplex Networks @ Next Generation Network Analytics Kolja Kleineberg
The document summarizes research on the hidden geometry of multiplex networks. It finds that real-world multiplex networks often have correlated geometric properties between network layers, with nodes maintaining similar radial and angular coordinates. This has implications like communities of nodes being similar across layers and hyperbolic distance in one layer predicting connections in another. A geometric multiplex model is introduced to generate realistic multiplex networks with tunable geometric correlations between layers.
ICPSR - Complex Systems Models in the Social Sciences - Lab Session 2 - Profe...Daniel Katz
This document provides an overview of the forest fire model simulation. It discusses:
(1) The setup procedure which initializes the world with green "patches" representing trees, at a random density.
(2) The "ignite" procedure which sets a random patch on fire to start the simulation.
(3) The fire then spreads deterministically from burning trees to neighboring trees based on the code rules, while the placement of trees was random.
The document explores modifying aspects of the model like changing the color of trees or direction of fire spread. It also discusses representing the dependencies in the code and analyzing the deterministic and random elements conceptually.
A novel cluster based wormhole avoidance algorithm for mobile adhoc networkscsandit
A severe type of network layer security attack called Wormhole attack can occur in MANET,
during which a malicious node captures packets from one location in the network, and tunnels
them to another colluding malicious node at a distant point, which replays them locally. This
paper presents a hierarchical cluster based Wormhole attack avoidance technique to avoid such
scenario. The concept of hierarchical clustering with a novel hierarchical 32-bit node
addressing scheme is used for avoiding the attacking path during the route discovery phase of
the DSR protocol, which is considered as the under lying routing protocol. Pinpointing the
location of the Wormhole nodes in the case of exposed attack is also given by using this method.
The document analyzes the wormhole attack in wireless ad hoc networks. It shows that a strategic placement of the wormhole can disrupt on average 32% of communications across the network. It also analyzes a more severe attack with multiple attackers and gives an upper bound of (1-1/n) of disrupted communications for n attackers. Finally, it proposes a new routing protocol to counter wormhole and other attacks by allowing routing as long as there is a non-faulty path between source and destination.
Geometric correlations in multiplexes and how they make them more robustKolja Kleineberg
This document discusses research on the structure and dynamics of multiplex networks. It begins by introducing the concept of multiplex networks, which have the same nodes existing across different network layers. It then discusses how degree correlations and geometric correlations between the positions of nodes in the hidden metric spaces underlying different network layers have been found in real multiplex systems. The document explores how these geometric correlations allow for applications like better identifying communities of nodes, improved link prediction between layers, and more efficient navigation across the network layers.
This document presents two papers on analyzing bursty topics from microblogs and modeling latent topic transitions in social media. The first paper proposes using temporal information from microblog posts and users' interests to detect bursty topics. The second paper introduces TM-LDA, a topic model that captures latent topic transitions over time in sequentially posted documents and efficiently updates online. Both papers aim to model topics in a temporally-aware manner from streaming social media data.
Secure multipath routing scheme using keyijfcstjournal
Multipath routing in WSN has been a long wish in security scenario where nodes on next-hop may be
targeted to compromise. Many proposals of Multipath routing has been proposed in ADHOC Networks but
under constrained from keying environment most seems ignorant. In WSN where crucial data is reported by
nodes in deployment area to their securely located Sink, route security has to be guaranteed. Under
dynamic load and selective attacks, availability of multiple secure paths is a boon and increases the
attacker efforts by many folds. We propose to build a subset of neighbors as our front towards destination
node. We also identified forwarders for query by base station. The front is optimally calculated to maintain
the security credential and avail multiple paths. According to our knowledge ours is a novel secure
multipath routing protocol for WSN. We established effectiveness of our proposal with mathematical
analysis.
Hidden geometric correlations in real multiplex networksKolja Kleineberg
Read the paper at http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3812.html
Real networks often form interacting parts of larger and more complex systems. Examples can be found in different domains, ranging from the Internet to structural and functional brain networks. Here, we show that these multiplex systems are not random combinations of single network layers. Instead, they are organized in specific ways dictated by hidden geometric correlations between the layers. We find that these correlations are significant in different real multiplexes, and form a key framework for answering many important questions. Specifically, we show that these geometric correlations facilitate the definition and detection of multidimensional communities, which are sets of nodes that are simultaneously similar in multiple layers. They also enable accurate trans-layer link prediction, meaning that connections in one layer can be predicted by observing the hidden geometric space of another layer. And they allow efficient targeted navigation in the multilayer system using only local knowledge, outperforming navigation in the single layers only if the geometric correlations are sufficiently strong.
Ballpark Figure Algorithms for Data Broadcast in Wireless NetworksEditor IJCATR
In wireless system allocation is a necessary purpose and show industry expensive dependability in message protocol design. In multihop wireless networks, equally, imposition by a node by reason of immediate transmissions as its neighbors makes it nontrivial to graph a minimum-latency transmit algorithm, which is known to be NP-complete. A simple ballpark figure algorithm for the one-to-all transmit problem that improves all previously documented guarantees for this problem. In All-to-all transmit problem where every node sends its own consequence to all complementary nodes. In the all-to-all transmit problem, we current two algorithms with ballpark figure ratios of 20 and 34, civilizing the greatest result. A communication wants to be transmitted establishment its resource to all the previous nodes in the network. There may be different messages to be broadcasted from several sources. Two or more nodes broadcast a communication to an ordinary neighbor at the same time; the frequent node will not collect any of this communication. We say that collide has occurred at the ordinary node. So any message protocol for wireless networks must dispute with the distress of difficulty in the wireless intermediate.
Full Communication in a Wireless Sensor Network by Merging Blocks of a Key Pr...cscpconf
Wireless Sensor Networks (WSN) are constraint by the limited resources available to its
constituting sensors. Thus the use of public-key cryptographyduring message exchange gets
forbidden. One has to invoke symmetric key techniques. This leads to key distribution in the
sensors which in itself is a major challenge. Again due to resource constraints, Key
Predistrubution (KPD) methods are preferred to other distribution techniques. It requires
predistribution of keys in nodes prior to deployment and establishing immediately once
deployed. However there are certain weaknesses in various existing KPD schemes. For
instance, often it is not guaranteed that any given pair of nodes communicate directly. This
leads one to revert to multi-hop communication involving intermediate sensor nodes resulting
in increased cost of communication. In this work a key predistribution technique using ReedSolomon
codes is considered which is faced with the above weakness. The authors suggests a
novel technique of merging certain number of sensors into blocks ensuring that the blocks
have full connectivity amongst themselves. Here the blocks are chosen in such a way that it
ensures no intra-node communication. Further this approach improves both time and space
complexity of the system
This document is the solutions manual for the textbook "Cryptography and Network Security, Fourth Edition" by William Stallings. It contains solutions to all review questions and homework problems from the textbook organized by chapter. The author, William Stallings, requests that any errors found in solutions or wording of problems be reported to help improve the accuracy of the manual.
Performance Evaluation of Computationally Efficient Energy Detection Based Sp...IJRST Journal
The rapid growth of bandwidth demanding wireless technologies has led to the problem of spectrum scarcity. However, studies show that licensed spectrum is underutilized. Cognitive radio technology promises a solution to the problem by allowing unlicensed users, access to the licensed bands opportunistically. A prime component of the cognitive radio technology is spectrum sensing. Many spectrum sensing techniques have been developed to sense the presence or not of a licensed user. This paper evaluates the performance of the energy detection based spectrum sensing technique in noisy, fading, jamming, interference environments. Both single user detection and cooperative detection situations were investigated. Closed form solutions for the probabilities of detection and false alarm were derived. The analytical results were varied by numerical computations using Monte Carlo method with MATLAB. The performance of the computationally efficient energy detection (CE-ED) techniques were evaluated by use of Receiver Operating Characteristics (ROC) curves over additive white Gaussian noise (AWGN) and fading (Rayleigh & Nakagami-m) channels. Results show that for single user detection, the energy detection technique performs better in AWGN channel than in the fading channel models. The performance of cooperative detection is better than single user detection in fading environments.
The Last Line Effect. Abstract: Micro-clones are tiny duplicated pieces of code; they typically comprise only a few statements or lines. In this paper, we expose the “last line effect”, the phenomenon that the last line or statement in a micro-clone is much more likely to contain an error than the previous lines or statements. We do this by analyzing 208 open source projects and reporting on 202 faulty micro-clones.
Detecting root of the rumor in social network using GSSSIRJET Journal
1) The document proposes a method to detect the root of rumors spreading in social networks using monitor nodes and the Greedy Source Set Size algorithm.
2) Monitor nodes record and report data to identify rumors and their sources based on which nodes received the information.
3) The GSSS algorithm aims to find the exact solution and improve efficiency for identifying rumor sources.
4) Three methods are used to identify the rumor root: identification method, reverse dissemination method, and microscopic rumor spreading model based on maximum likelihood.
Implementation of Spanning Tree Protocol using ns-3Naishil Shah
This document discusses the implementation of the Spanning Tree Protocol (STP) using the ns-3 network simulator. STP is used to prevent bridge loops in layer 2 Ethernet networks. The authors first tried implementing STP by exchanging HELLO messages between nodes but were unsuccessful. They then used Prim's algorithm on the adjacency matrix output from ns-3 to generate a minimum spanning tree and remove loops. NetAnim was used to visualize the topology before and after applying Prim's algorithm.
FAST DETECTION OF DDOS ATTACKS USING NON-ADAPTIVE GROUP TESTINGIJNSA Journal
This document proposes a method for fast detection of DDoS attacks using non-adaptive group testing (NAGT). It begins with background on DDoS attacks and group testing techniques. It then describes using a strongly explicit d-disjunct matrix in NAGT to map IP addresses to "tests" performed by routers. The router counters would indicate potential hot items (attackers or victims). Two decoding algorithms are presented to identify the hot items from the test results with poly-log time complexity meeting data stream requirements. The method aims to provide early warning of DDoS attacks through efficient group testing of IP packets.
FAST DETECTION OF DDOS ATTACKS USING NON-ADAPTIVE GROUP TESTINGIJNSA Journal
Network security has become more important role today to personal users and organizations. Denial-ofService (DoS) and Distributed Denial-of-Service (DDoS) attacks are serious problem in network. The major challenges in design of an efficient algorithm in data stream are one-pass over the input, poly-log space, poly-log update time and poly-log reporting time. In this paper, we use strongly explicit construction d-disjunct matrices in Non-adaptive group testing (NAGT) to adapt these requirements and propose a solution for fast detecting DoS and DDoS attacks based on NAGT approach.
Unmanned aerial vehicles (UAVs) have become very popular recently for both civil uses and potential commercial uses, such as law enforcement, crop survey, grocery delivery, and photographing, although they were mainly used for military purposes before. Researchers need the help of simulations when they design and test new protocols for UAV networks because simulations can be done for a network of a size
that a test bed can hardly approach. In the simulation of an UAV network it is important to choose a radio propagation model for the links in the network. We study the shadowing radio propagation model in this paper and compare it with the free space model, both of which are available in the ns2 network simulation package. We also show how the choice of the parameters of the shadowing model would impact on the
network performance of a UAV network.
This document summarizes a study on the hidden node problem in IEEE 802.15.4/ZigBee wireless sensor networks. The study used an OPNET simulation model to evaluate the impact of hidden nodes on network performance. The results showed that as traffic load increased, goodput ratio and packet delivery time decreased while energy consumption per bit increased, due to more frequent packet collisions from hidden nodes. The hidden node problem caused significant packet loss and degraded network performance. Further work to address this problem by implementing RTS/CTS handshaking was proposed.
This document discusses community detection in networks. It begins by introducing common network properties like small world phenomenon and power law degree distribution. It then discusses challenges in community detection for large networks. Various community detection algorithms are reviewed, including modularity maximization and stochastic block models. Issues with existing algorithms like resolution limits and sensitivity to network properties are explored. A new local algorithm is proposed that detects communities by maximizing a localized clique index, aiming to balance type I and type II errors. The algorithm allows parameter p to vary between subnetworks for more flexible community detection in complex real-world networks.
Secure data storage over distributed nodes in network through broadcast techn...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Overlapping community detection in Large-Scale Networks using BigCLAM model b...Thang Nguyen
In this undergraduate thesis, I provide a general view of communities and its the real life applications. In recent years, with the rapid growth of network scale, it is a difficult task to detect overlapping communities in large-scale networks for state of the art methods. This method is implemented in the Apache Spark framework for its power in distributed parallel computation.
The main contributions of this work include:
Introduce BigCLAM models proposed by Yang and Leskovec (2013).
proposed a few methods convex optimization.
implemented BigCLAM in Apache Spark is evaluated as lightning-fast cluster computing to able detect community in the large-scale networks.
https://thangdnsf.github.io/research.html
Mobile ad hoc network (MANET) is an autonomous system of mobile nodes. Each node operates not only as an end system, but also as a router to forward packets. The nodes are free to move about and organize themselves into a network. These cause extra challenges on security. In this paper, evaluation of prominent on-demand routing protocol i.e. AODV,MAODV,RAODV has been done by varying the network size. An effort has been carried out to do the performance evaluation of these protocols using random way point model. The simulator used is NS 2.34. The performance of either protocol has been studied by using a self created network scenario with respect to pause time.
Experimental simulation and real world study on wi fi ad-hoc mode for differe...Nazmul Hossain Rakib
The Ad-Hoc mode for wireless communication is not used frequently. But the demand for Wi-Fi communication is continuously increasing as use of Smart-phones and Laptops has enormously popular recent years. Through Ad-Hoc mode users can communicate point to point with mobility feature without using any central BSS. Wireless Ad-Hoc mode uses electromagnetic wave and so this technology has losses and limitations caused by free space propagation media as well as attenuation for interferences.
Although unmanned aerial vehicles (UAVs) were mostly studied and used for military purposes before, they
have become very popular recently for both civil uses, such as law enforcement and crop survey, and for
potential commercial uses such as grocery delivery and Internet extension. Researchers investigating new
networking protocols for UAV networks usually need the help of simulations to test their protocol designs,
particularly when networks of large scales are desired in their tests. One choice that researchers need to
make in the simulation of UAV networks is the radio propagation model for the air links. In this paper we
compare the three radio propagation models that are available in the ns2 network simulation package and
investigate if the choice of one particular model would have a significant impact on the simulation results
for UAV networks.
A Genetic Algorithm for Reliability Evaluation of a Stochastic-Flow Network w...CSCJournals
The paper presents a genetic algorithm to compute the reliability of a stochastic- flow network in which each arc or node has several capacitis and may fail. I.e. Calculate the system reliability such that the maximum flow is not less than a given demand. The algorithm is based on generating all lower boundary points for the given demand and than the system reliability can be calculated in terms of such points. The proposed algorithm can be used for a network with large number of nodes and links. Also, the paper investigates the problems that are found in the solutions that obtained by using other previous methods.
Black hole and greyhole attack in wireless mesh networkAnbarasu S
1) The document discusses black hole and greyhole attacks in wireless mesh networks. These are network layer attacks where malicious nodes drop packets instead of forwarding them, disrupting routing.
2) It analyzes these attacks through simulation in OPNET, finding they reduce throughput and increase network load. Implementing OLSR routing protocol helps mitigate but not eliminate the attacks' effects.
3) Greyhole attacks are more difficult to detect than black holes, as nodes sometimes forward packets. The paper evaluates attacks' performance impact and potential prevention techniques for securing the network layer.
Secure multipath routing scheme using keyijfcstjournal
Multipath routing in WSN has been a long wish in security scenario where nodes on next-hop may be
targeted to compromise. Many proposals of Multipath routing has been proposed in ADHOC Networks but
under constrained from keying environment most seems ignorant. In WSN where crucial data is reported by
nodes in deployment area to their securely located Sink, route security has to be guaranteed. Under
dynamic load and selective attacks, availability of multiple secure paths is a boon and increases the
attacker efforts by many folds. We propose to build a subset of neighbors as our front towards destination
node. We also identified forwarders for query by base station. The front is optimally calculated to maintain
the security credential and avail multiple paths. According to our knowledge ours is a novel secure
multipath routing protocol for WSN. We established effectiveness of our proposal with mathematical
analysis.
Hidden geometric correlations in real multiplex networksKolja Kleineberg
Read the paper at http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3812.html
Real networks often form interacting parts of larger and more complex systems. Examples can be found in different domains, ranging from the Internet to structural and functional brain networks. Here, we show that these multiplex systems are not random combinations of single network layers. Instead, they are organized in specific ways dictated by hidden geometric correlations between the layers. We find that these correlations are significant in different real multiplexes, and form a key framework for answering many important questions. Specifically, we show that these geometric correlations facilitate the definition and detection of multidimensional communities, which are sets of nodes that are simultaneously similar in multiple layers. They also enable accurate trans-layer link prediction, meaning that connections in one layer can be predicted by observing the hidden geometric space of another layer. And they allow efficient targeted navigation in the multilayer system using only local knowledge, outperforming navigation in the single layers only if the geometric correlations are sufficiently strong.
Ballpark Figure Algorithms for Data Broadcast in Wireless NetworksEditor IJCATR
In wireless system allocation is a necessary purpose and show industry expensive dependability in message protocol design. In multihop wireless networks, equally, imposition by a node by reason of immediate transmissions as its neighbors makes it nontrivial to graph a minimum-latency transmit algorithm, which is known to be NP-complete. A simple ballpark figure algorithm for the one-to-all transmit problem that improves all previously documented guarantees for this problem. In All-to-all transmit problem where every node sends its own consequence to all complementary nodes. In the all-to-all transmit problem, we current two algorithms with ballpark figure ratios of 20 and 34, civilizing the greatest result. A communication wants to be transmitted establishment its resource to all the previous nodes in the network. There may be different messages to be broadcasted from several sources. Two or more nodes broadcast a communication to an ordinary neighbor at the same time; the frequent node will not collect any of this communication. We say that collide has occurred at the ordinary node. So any message protocol for wireless networks must dispute with the distress of difficulty in the wireless intermediate.
Full Communication in a Wireless Sensor Network by Merging Blocks of a Key Pr...cscpconf
Wireless Sensor Networks (WSN) are constraint by the limited resources available to its
constituting sensors. Thus the use of public-key cryptographyduring message exchange gets
forbidden. One has to invoke symmetric key techniques. This leads to key distribution in the
sensors which in itself is a major challenge. Again due to resource constraints, Key
Predistrubution (KPD) methods are preferred to other distribution techniques. It requires
predistribution of keys in nodes prior to deployment and establishing immediately once
deployed. However there are certain weaknesses in various existing KPD schemes. For
instance, often it is not guaranteed that any given pair of nodes communicate directly. This
leads one to revert to multi-hop communication involving intermediate sensor nodes resulting
in increased cost of communication. In this work a key predistribution technique using ReedSolomon
codes is considered which is faced with the above weakness. The authors suggests a
novel technique of merging certain number of sensors into blocks ensuring that the blocks
have full connectivity amongst themselves. Here the blocks are chosen in such a way that it
ensures no intra-node communication. Further this approach improves both time and space
complexity of the system
This document is the solutions manual for the textbook "Cryptography and Network Security, Fourth Edition" by William Stallings. It contains solutions to all review questions and homework problems from the textbook organized by chapter. The author, William Stallings, requests that any errors found in solutions or wording of problems be reported to help improve the accuracy of the manual.
Performance Evaluation of Computationally Efficient Energy Detection Based Sp...IJRST Journal
The rapid growth of bandwidth demanding wireless technologies has led to the problem of spectrum scarcity. However, studies show that licensed spectrum is underutilized. Cognitive radio technology promises a solution to the problem by allowing unlicensed users, access to the licensed bands opportunistically. A prime component of the cognitive radio technology is spectrum sensing. Many spectrum sensing techniques have been developed to sense the presence or not of a licensed user. This paper evaluates the performance of the energy detection based spectrum sensing technique in noisy, fading, jamming, interference environments. Both single user detection and cooperative detection situations were investigated. Closed form solutions for the probabilities of detection and false alarm were derived. The analytical results were varied by numerical computations using Monte Carlo method with MATLAB. The performance of the computationally efficient energy detection (CE-ED) techniques were evaluated by use of Receiver Operating Characteristics (ROC) curves over additive white Gaussian noise (AWGN) and fading (Rayleigh & Nakagami-m) channels. Results show that for single user detection, the energy detection technique performs better in AWGN channel than in the fading channel models. The performance of cooperative detection is better than single user detection in fading environments.
The Last Line Effect. Abstract: Micro-clones are tiny duplicated pieces of code; they typically comprise only a few statements or lines. In this paper, we expose the “last line effect”, the phenomenon that the last line or statement in a micro-clone is much more likely to contain an error than the previous lines or statements. We do this by analyzing 208 open source projects and reporting on 202 faulty micro-clones.
Detecting root of the rumor in social network using GSSSIRJET Journal
1) The document proposes a method to detect the root of rumors spreading in social networks using monitor nodes and the Greedy Source Set Size algorithm.
2) Monitor nodes record and report data to identify rumors and their sources based on which nodes received the information.
3) The GSSS algorithm aims to find the exact solution and improve efficiency for identifying rumor sources.
4) Three methods are used to identify the rumor root: identification method, reverse dissemination method, and microscopic rumor spreading model based on maximum likelihood.
Implementation of Spanning Tree Protocol using ns-3Naishil Shah
This document discusses the implementation of the Spanning Tree Protocol (STP) using the ns-3 network simulator. STP is used to prevent bridge loops in layer 2 Ethernet networks. The authors first tried implementing STP by exchanging HELLO messages between nodes but were unsuccessful. They then used Prim's algorithm on the adjacency matrix output from ns-3 to generate a minimum spanning tree and remove loops. NetAnim was used to visualize the topology before and after applying Prim's algorithm.
FAST DETECTION OF DDOS ATTACKS USING NON-ADAPTIVE GROUP TESTINGIJNSA Journal
This document proposes a method for fast detection of DDoS attacks using non-adaptive group testing (NAGT). It begins with background on DDoS attacks and group testing techniques. It then describes using a strongly explicit d-disjunct matrix in NAGT to map IP addresses to "tests" performed by routers. The router counters would indicate potential hot items (attackers or victims). Two decoding algorithms are presented to identify the hot items from the test results with poly-log time complexity meeting data stream requirements. The method aims to provide early warning of DDoS attacks through efficient group testing of IP packets.
FAST DETECTION OF DDOS ATTACKS USING NON-ADAPTIVE GROUP TESTINGIJNSA Journal
Network security has become more important role today to personal users and organizations. Denial-ofService (DoS) and Distributed Denial-of-Service (DDoS) attacks are serious problem in network. The major challenges in design of an efficient algorithm in data stream are one-pass over the input, poly-log space, poly-log update time and poly-log reporting time. In this paper, we use strongly explicit construction d-disjunct matrices in Non-adaptive group testing (NAGT) to adapt these requirements and propose a solution for fast detecting DoS and DDoS attacks based on NAGT approach.
Unmanned aerial vehicles (UAVs) have become very popular recently for both civil uses and potential commercial uses, such as law enforcement, crop survey, grocery delivery, and photographing, although they were mainly used for military purposes before. Researchers need the help of simulations when they design and test new protocols for UAV networks because simulations can be done for a network of a size
that a test bed can hardly approach. In the simulation of an UAV network it is important to choose a radio propagation model for the links in the network. We study the shadowing radio propagation model in this paper and compare it with the free space model, both of which are available in the ns2 network simulation package. We also show how the choice of the parameters of the shadowing model would impact on the
network performance of a UAV network.
This document summarizes a study on the hidden node problem in IEEE 802.15.4/ZigBee wireless sensor networks. The study used an OPNET simulation model to evaluate the impact of hidden nodes on network performance. The results showed that as traffic load increased, goodput ratio and packet delivery time decreased while energy consumption per bit increased, due to more frequent packet collisions from hidden nodes. The hidden node problem caused significant packet loss and degraded network performance. Further work to address this problem by implementing RTS/CTS handshaking was proposed.
This document discusses community detection in networks. It begins by introducing common network properties like small world phenomenon and power law degree distribution. It then discusses challenges in community detection for large networks. Various community detection algorithms are reviewed, including modularity maximization and stochastic block models. Issues with existing algorithms like resolution limits and sensitivity to network properties are explored. A new local algorithm is proposed that detects communities by maximizing a localized clique index, aiming to balance type I and type II errors. The algorithm allows parameter p to vary between subnetworks for more flexible community detection in complex real-world networks.
Secure data storage over distributed nodes in network through broadcast techn...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Overlapping community detection in Large-Scale Networks using BigCLAM model b...Thang Nguyen
In this undergraduate thesis, I provide a general view of communities and its the real life applications. In recent years, with the rapid growth of network scale, it is a difficult task to detect overlapping communities in large-scale networks for state of the art methods. This method is implemented in the Apache Spark framework for its power in distributed parallel computation.
The main contributions of this work include:
Introduce BigCLAM models proposed by Yang and Leskovec (2013).
proposed a few methods convex optimization.
implemented BigCLAM in Apache Spark is evaluated as lightning-fast cluster computing to able detect community in the large-scale networks.
https://thangdnsf.github.io/research.html
Mobile ad hoc network (MANET) is an autonomous system of mobile nodes. Each node operates not only as an end system, but also as a router to forward packets. The nodes are free to move about and organize themselves into a network. These cause extra challenges on security. In this paper, evaluation of prominent on-demand routing protocol i.e. AODV,MAODV,RAODV has been done by varying the network size. An effort has been carried out to do the performance evaluation of these protocols using random way point model. The simulator used is NS 2.34. The performance of either protocol has been studied by using a self created network scenario with respect to pause time.
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investigate if the choice of one particular model would have a significant impact on the simulation results
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Black hole and greyhole attack in wireless mesh networkAnbarasu S
1) The document discusses black hole and greyhole attacks in wireless mesh networks. These are network layer attacks where malicious nodes drop packets instead of forwarding them, disrupting routing.
2) It analyzes these attacks through simulation in OPNET, finding they reduce throughput and increase network load. Implementing OLSR routing protocol helps mitigate but not eliminate the attacks' effects.
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Analysis and reactive measures on the blackhole attackJyotiVERMA176
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A beamforming comparative study of least mean square, genetic algorithm and g...TELKOMNIKA JOURNAL
Multipath environment is a limitation fact in optimized usage of wireless networks. Using smart antenna and beamforming algorithms contributed to that subscribers get a higher-gain signal and better directivity as well as reduce the consumed power for users and the mobile base stations by adjusting the appropriate weights for each element in the antenna array that leads to reducing interference anddirecting the main beam to wanted user. In this paper, the performance of three of beamforming algorithms in multipath environment in terms of directivity and side lobe level reduction has been studied and compared, which are least mean square (LMS), genetic algorithm (GA) and grey wolf optimization (GWO) technique. The simulation result appears that LMS algorithm aids us to get the best directivity followed by the GWO, and we may get most sidelobe level reduction by using the GA algorithm, followed by LMS algorithm in second rank.
ICPSR - Complex Systems Models in the Social Sciences - Lecture 3 - Professor...Daniel Katz
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Similar to Least cost rumor blocking in social networks (20)
3. Social Network
Social network is a social structure
made up of individuals and relations
between these individuals
Social network provides a
platform for influence diffusion
4. Applications
Single cascade
Viral marketing
Recommender systems
Feed ranking
……
Multiple cascades
Political election
Multiple products promotion
Rumor/misinformation controlling
……
5. Social network properties
Small-world effect
The average distance between vertices in a network is short.
Power-law or exponential form
There are many nodes with low degree and a small number with
high degree.
Clustering or network transitivity
Two vertices that are both neighbors of the same third vertex have
a high probability of also being neighbors of one another.
Community structure
The connections within the same community are dense and
between communities are sparse.
6. Influence spreads fast within the same
community while slow across different
communities.
7.
8. It said that the president of
Syria is dead, which hit the
twitter greatly and was
circulated fast among the
population, leading to a sharp,
quick increase in the price of
oil.
9. In August, 2012, thousands
of people in Ghazni
province left their houses in
the middle of the night in
panic after the rumor of
earthquake.
10.
11. Problem Setting
Rumors generated in a community will influence the
members in the network.
Find protectors to reduce the influence of rumors or protect
the most members in the network.
Real-world limitation: the overhead spent on
protectors and protected members should be
balanced.
Rumors spread very fast within their community---too much cost
Rumors spread slow across different communities---little cost
Find least number of protectors to reduce rumor influence
to the members in other communities.
12. Our Tasks
Determine influence diffusion models.
Design efficient algorithms to find protectors to reduce
influence from rumors.
Obtain data of particular social networks to evaluate our
algorithms.
13. Outline
Model of influence diffusion
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
14. Outline
Model of influence diffusion
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
15. Our Two Influence Diffusion Models
Two cascades: rumors and protectors;
Diffusion starts time: the same;
Tie breaking rule: protectors dominate rumors;
Status of each node: inactive, rumored, protected;
Monotonicity assumption: the status of rumored or protected
never change.
16. Outline
Two influence diffusion models
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
17. Deterministic One Activate Many Model
When a node becomes active (rumored or protected) , it has
a single chance to activate all of its currently inactive (not
rumored and not protected) neighbors.
The activation attempts succeed with a probability 1.
18. Example
1
3
4
5
2
6
1 is a rumor, 6 is a protector.
step 1: 1--2,3; 6--2,4. 2 and 4 is protected, 3 is rumored.
19. Example
1
3
5
2
6
4
step 2: 4--5. 5 is protected.
20. Outline
Two influence diffusion models
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
21. Opportunistic One Activate One Model
At each step, each active (rumored or protected) node u can
only choose one of its neighbors as its target, and each
neighbor can be chosen with a probability of 1/deg(u).
Each active (rumored or protected) node has unlimited
chance to select the same node as its target.
22. Example
1
3
4
5
2
6
1 is a rumor, 6 is a protector.
step 1:1--2, 6--2. 2 is protected.
23. Example
1
3
4
5
2
6
step 2:1--3, 6--2. 3 is rumored.
24. Example
1
3
4
5
2
6
step 3:1--2, 3--4, 6--4. 4 is protected.
25. Example
1
3
4
5
2
6
step 4:1--3, 3--2, 6--4, 4--5. 5 is protected.
26. Outline
Two influence diffusion models
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
27. Least Cost Rumor Blocking Problem (LCRB)
Bridge ends:
form a vertex set;
belong to neigborhood communities of rumor community;
each can be reached from the rumors before others in its
community.
C0
C2
C1
Red node is a rumor;
Yellow nodes are bridges ends.
28. Outline
Two influence diffusion models
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
29. LCRB-D problem for the DOAM model
Given the community structure and rumors with its
community, find least number of protectors to protect
all of the bridge ends .
30. Set Cover Based Greedy (SCBG) Algorithm
Main idea
Convert to set cover problem using Breadth First
Search (BFS) method.
Three stages:
construct Rumor Forward Search Trees (RFST)--bridge
ends
construct Bridge End Backward Search Trees (BEBST)--
protector candidates
construct vertex sets used in set cover problem
32. Rumor 4 Forward Search Tree
4
1 2 5
3 12
8
The minimal hops:
1 hop between 4 and 5;
2 hops between 4 and 12;
3 hops between 4 and 8.
5,8,12 are the bridge ends.
33. 7 6
5
1
3
4
2
8
9
10
11
12
14
Blue nodes are
protector candidates.
34. Bridge End Backward Search Trees
7 4
5
3 4
4
11 2
9 10 3 2
8 12
Record the protector candidate sets for each bridge end:
5: {5,7}; 8:{2,3,8,9,10,11}; 12:{2,3,12}
35. Construct vertex sets in set cover problem
Find the bridge ends that each candidate can protect:
2:{8,12}; 3:{8,12} ; 5:{5}; 7:{5}; 8:{8}; 9:{8}; 10:{8};11{8}; 12{12}
Apply the Greedy algorithm
• choose 2 or 3 , bridge ends 8 and 12 are protected;
• choose 5 or 7, bridge end 5 is protected;
• the output is {2,5} or {2,7} or {3,5} or {3,7}.
36. Theoretical Results
There is a polynomial time O(ln n)−approximation algorithm for the LCRB-D
problem, where n is the number of vertices in the bridge end set.
If the LCRB-D problem has an approximation algorithm with ratio k(n) if
and only if the set cover problem has an approximation algorithm with ratio
k(n).
37. Experiments
Two Social networks
• Collaboration Network: is from the e-print arXiv and covers scientific
collaborations between authors with papers submitted to High Energy
Physics. If an author i co-authored a paper with author j, then the graph
contains an undirected directed edge between i to j,7.73 average degree.
• Email Network: covers all the email communications within a dataset of
around half million emails. Nodes of the network are email addresses and
if an address i sends at least one email to address j, a directed edge from i
to j is added in the graph, 10.0 average degree.
38. Hep:
community size 308,
bridge end size 387.
Email:
• community size 80,
bridge end size 135.
• community size 2631,
bridge end size 2250.
Our algorithm performs the best,
especially in the third community.
39. Outline
Two influence diffusion models
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
40. LCRB-P problem for OPOAO model
Given the community structure and rumors with its community,
find least number of protectors to protect α fraction of the bridge
ends, where 0 <α <=1.
Influence function σ(A) of node set A:
expected number of nodes that would be rumored if set A is not selected
as the protector seed initially
41. Results
A properties: (to be proved)
Non-negative:
Monotone:
Submodular:
A 0
A v (A)
Let S be a finite set;
A set function is submodular iff satisfies diminishing
2 : S
returns property. That is,
A B S,vS B
(A v) (A) (B v) (B)
42. The Greedy Algorithm
Start with an empty set A;
While the number of protected bridge ends has not reach α fraction
of the number of all the bridge ends:
Add node v to S such that σ(A+v)-σ(A) is maximized.
43. Proof of Submodularity
Timestamp assignment of rumor diffusion
x y
u v
w z
x y
1_x 3_x
u v
w z
1_x
2_x
4_x
3_x
1_y
2_y
3_y
4_y
2_y
4_y
3_y
2_x
3_x
4_x
4_y
4_x
3_x
1_y
3_y
2_x
4_y
4_x 2_y
3_x
44. Proof of Submodularity
Prove the submodularity of cardinality function |PB(A)|
PB(A): the protector blocking set on bridge ends, in which
individuals will be rumored if the protector seed set is empty but is
not rumored if the protector seed set is A.
Rumor/protector random diffusion graphs-Gr/Gp.
Find the oldest (smallest) timestamp among the incoming edges of
each bridge end u in Gr and Gp, and compare them, if the oldest
one in Gp is older than the one in Gr, then u can be protected,
otherwise, it will be rumored.
45. Submodularity of function σ(A)
Fact: A non-negative linear combination of monotone and
submodular functions is still monotone and submodular.
A E PB A
( ( ) )
Gr Gp
prob Gr Gp are randomlygenerated PB A
( , ) ( )
( , )
Gr ,
Gp
Probabilities are non-negative;
|PB(A)| is submodular;
σ(A) is submodular.
47. Outline
Two influence diffusion models
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
48. Conclusions
Introduce two influence diffusion models
• Deterministic One Activate Many --DOAM
• Opportunistic One Activate One--OPOAO
The least cost rumor blocking (LCRB) problem in those two
models
• LCRB-D problem under the DOAM—protect all the bridge ends
Design set cover based greedy algorithm (SCBG)
Run experiments over collaboration network and email network
• LCRB-P problem under the OPOAO—protect α fraction of the bridge ends
Prove the submodularity of influence function σ(A);
using timestamp assaignment strategy
Design greedy algorithm
Run experiments over collaboration network and email network
49. Outline
Two influence diffusion models
Deterministic One Activate Many (DOAM)
Opportunistic One Activate One (OPOAO)
Least cost rumor blocking problem
Algorithm and experimental results under the DOAM
Algorithm and experimental results under the OPOAO
Conclusions
Future works
50. Future Works
The greedy algorithm in the OPOAO model is time consuming,
explore efficient algorithms for the LCRB-P problem.
Time is an important factor in rumor diffusion, consider the rumor
blocking problem with time constraint.
It is hard to locate rumor sources, find algorithms to estimate
rumor sources to control rumor diffusion efficiently.