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Nanosized dysprosia (NSD) and Gd-doped NSD (GNSD) are an efficient and eco-friendly magnetocaloric material system for magnetic refrigeration that can potentially replace the existing environmentally harmful chlorofluorocarbon (CFC)-based refrigeration system. The NSDs were synthesised using the sol–gel process, and the structural, optical and magnetocaloric properties of materials were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), ultra-violet spectroscopy (UV) and superconducting quantum interference device (SQUID). The magnetic and electronic properties of NSD and GNSD were investigated using first principle calculations. The magnetocaloric studies revealed that incorporation of Gd3+ in NSD induced maximum magnetic entropy change of 17.1 JKg−1 K−1 at 8 K with 5 T. With the notable low transition temperature, NSD and GNSD could potentially be used for cryo-cooling applications.

Interference in Wireless Sensor Network (WSN) predominantly affects the performance of the WSN. Energy consumption in WSN is one of the greatest concerns in the current generation. This work presents an approach for interference measurement and interference mitigation in point to point network. The nodes are distributed in the network and interference is measured by grouping the nodes in the region of a specific diameter. Hence this approach is scalable and isextended to large scale WSN. Interference is measured in two stages. In the first stage, interference is overcome by allocating time slots to the node stations in Time Division Multiple Access (TDMA) fashion. The node area is split into larger regions and smaller regions. The time slots are allocated to smaller regions in TDMA fashion. A TDMA based time slot allocation algorithm is proposed in this paper to enable reuse of timeslots with minimal interference between smaller regions. In the second stage, the network density and control parameter is introduced to reduce interference in a minor level within smaller node regions. The algorithm issimulated and the system is tested with varying control parameter. The node-level interference and the energy dissipation at nodes are captured by varying the node density of the network. The results indicate that the proposed approach measures the interference and mitigates with minimal energy consumption at nodes and with less overhead transmission.

La2NiMnO6 double perovskite material that simultaneously exhibits both electric and magnetic ordering is used in energy-efficient electronic applications due to its lower power dissipation. The magnetic and electric ordering of Ni and Mn depend on the site occupancy and exchange mechanism driven by the anions, making La2NiMnO6 a widely explored material for such studies. The magnetocaloric properties of A-site-doped (Sr2+, Gd3+) double perovskite La2NiMnO6 have been investigated experimentally. The synthesized samples showed Pbnm orthorhombic symmetry with P21/n configuration. The Curie temperature (TC) of La2NiMnO6 (LMN) increased from 277 K to 284 K upon Gd doping due to strong exchange interactions and long-range ordering of Ni2+/Mn4+. Meanwhile, the Tc of LMN was observed to be 268 K upon Sr2+ doping, suggesting the possibility of antiferromagnetic ordering. Sr2+-doped (hole-doped) LMN showed lower Tc, magnetic entropy, and relative cooling power (RCP), which may be due to the increase in antisite disorder and exchange bias effect. The chemical stability, tunable transition temperature around room temperature with good control over entropy, wider operating temperature range, and high RCP at lower applied magnetic field make LMN and A-site-doped LMN potential refrigerant materials for use in energy-efficient room-temperature magnetic cooling systems.

Wireless Sensor Networks (WSN) is in large use in today’s world against the challenges encountered in the Sensor world. Energy consumption, routing, interference mitigation are a matter of concern in WSN. Perhaps, overruling interference mitigation would solve a number of interconnected problems in WSN. The proposed work is narrowed down to minimize interference in distributed homogenous WSN, ensuring that all the nodes in the network operate with the same transmission power. In this paper, an optimal shortest distance algorithm, Dynamic-Optimal Shortest Path Algorithm (DOSPA) is proposed to identify the shortest path in communication between point to point nodes. As the data traverses a number of intermediary nodes, a privileged network topology has to be built to ensure proper transmission of data. An ideal network topology is hence built dynamically for data transmission. However, a collision between data packets in interconnecting nodes is likely to occur. Furthermore, to minimize collision a non-persistent round-robin CSMA/CD algorithm is proposed. We study the network throughput, packet delay, corruption ratio by increasing the number of nodes and hence also analyzing the system in saturation state. It’s found that Packet Corruption Ratio (PCR) with CSMA+DOSPA is minimized compared to CSMA. Thus, interference reduction in distributed homogenous nodes is substantially minimized.

The effect of electron beam rapid thermal annealing (ERTA) on the crystallographic, structural, magnetic and magnetocaloric properties of Sr doped M-type barium hexaferrite thin films (Ba1−xSrxFe12O19) deposited with set optimized parameters on silicon (001) substrates were investigated. Amorphous to crystalline phase transitions occurred when the as-deposited thin films were annealed, however crystallinity reduced as a function of Sr concentration. The as-deposited thin films showed uniform grain size and distribution with reduction in grain size as a function of Sr concentration, whereas annealed thin films showed increase in agglomerated structures as a function of Sr concentration. As-deposited thin films with x = 0, 0.05 and 0.1 showed weak ferromagnetic response. Magnetic hysteresis loops and magnetic force microscopy images indicate improved c-axis in-plane magnetization with reduced coercivity for Sr doped thin films and saturation magnetization for thin films subjected to ERTA. The Arrott plots in positive quadrant suggested a typical M-type ferrite behaviour with second-order ferromagnetic phase transitions around the Curie temperature. The entropy changes associated with magnetic phase transitions were determined using magnetization measurements performed in the range of 50–105 K for as-deposited and 65–125 K for ERTA samples under different magnetic fields. The calculated maximum relative cooling power (RCP) of the as-deposited and ERTA thin films are 1941 mJ/cc and 3065 mJ/cc for 50 kOe magnetic fields. This suggests that Ba1−xSrxFe12O19 with x = 1 is a promising candidate for micro and nano magnetic refrigeration systems.

Cloud technology is emerging as a widely accepted technology in the recent years due to its robust nature. Cloud computation is basically developed on the fact that the resources can be shared between numerous devices to achieve efficient network operation among devices with minimized computation expenses. However, the sharing nature poses a security risk for the devices whose resources are being shared. Almost in all the existing works on cloud security, a single trusted third party (TTP) is used for key issue and authorization. However, using a single TTP may results in single-point failure and security risks. Most of the previous works on cloud security focus on storage security rather than considering the computation security. In order to solve these issues, in this paper, multi-authority-based file hierarchy hidden CP-ABE scheme for cloud security is proposed. In this scheme, the files are arranged in hierarchical order based on their attribute weights. Then when a cloud user needs certain resources, it requests the cloud service provider (CSP). The CSP links with the cloud owner to provide the requested file after encrypting it. The cloud server encrypts and places the encrypted file in CSP, which is later retrieved by cloud user. In this way, all the files that are being used are encrypted along with strict authentication to ensure cloud security.

People-centric sensing (PCS) system is gaining popularity in the current technology world due to its ability to enhance the mobile device into a global mobile sensing device. But, PCS system is still suffering from security risks related to users privacy risks since the data being sensed by PCS are capable of allowing the attackers to gain privacy information related to the user. Hence, user privacy security is a main concern in the PCS system. In this paper, we propose to develop an efficient privacy-preserving fault tolerance aggregation technique for the PCS system. The proposed technique will consider registration of the involved mobile nodes and access point as an important initial step. Then, the data message being transmitted will be encrypted into reports and forwarded in a highly secure manner. Finally, the data will be decrypted and retrieved at the destination based on the homomorphic encryption and decryption mechanism. In this way, the privacy of the user is maintained secure and the process is made more tolerant toward fault in order to enhance efficient network operation. We evaluate the performance of the protocol according to the parameters like communication overhead, delay and delivery ratio.

Germanene, silicene, stanene, phosphorene and graphene are some of single atomic materials with novel properties. In this paper, we explored bilayer germanene-based Double Gate-Field Effect Transistor (DG-FET) with various strains and deformations using Density Functional Theory (DFT) and Green’s approach by first-principle calculations. The DG-FET of 1.6 nm width, 6 nm channel length (Lch) and HfO2 as gate dielectric has been modeled. For intrinsic deformation of germanene bilayer, we have enforced minute mechanical deformation of wrap and twist (5°) and ripple (0.5 A) on germanene bilayer channel material. By using NEGF formalism, I–V Characteristics of various strains and deformation tailored DG-FET was calculated. Our results show that rough edge and single vacancy (5–9) in bilayer germanene diminishes the current around 47% and 58% respectively as compared with pristine bilayer germanene. In case of strain tailored bilayer DG-FET, multiple NDR regions were observed which can be utilized in building stable multiple logic states in digital circuits and high frequency oscillators using negative resistive techniques.

In the past two decades, there has been a fast growth in the heterogeneous wired-wireless network which connects variety of networks such as wired network, wireless network, high speed network and sensor network with the Internet. Since the wired network and wireless network use the different technologies, there is a necessity of developing new protocols or redesigning of existing protocols. Transmission Control Protocol is redesigned to achieve the reliable and effective communication in the heterogeneous wired-wireless network. The basic assumption made in Transmission Control Protocol is that the packet losses are caused by the network congestion but in case of wireless network, the packet losses may be due to temporary link failure, high Bit-Error-Rate etc. Hence the congestion avoidance algorithm of Transmission Control Protocol needs to be redesigned to cope with heterogeneous wired-wireless network. Therefore in this paper, we propose a congestion avoidance algorithm which differentiates the cause of packet losses. The essential components of proposed algorithm are round-trip-time estimation, backlogged packet estimation, channel status notification, loss differentiation algorithm and congestion window control. A round-trip-time estimation using ARIMA(2,1,1) model is proposed in this paper which estimates the sudden changes in the round trip time. It helps us to estimate the backlogged packet and thereby differentiating the congestive packet loss from non-congestive packet loss. In addition, we use the received signal strength of wireless receiver to differentiate the packet losses. Based on the packet loss differentiation, the congestion window size is controlled to avoid the congestion in the network. The proposed algorithm is simulated using network simulator under different network environments. From the simulation results, it is realized that the proposed congestion avoidance algorithm performs well in the heterogeneous wired-wireless network.

In recent years, wireless sensor networks have become an emerging technology in industries, environment monitoring and health care monitoring systems and so on. However, sensor node is a resource-constrained device in terms of memory, bandwidth and energy. These constraints impose congestion in the network, leading to large number of packet drops, low throughput and significant wastage of energy because of retransmission. This study presents a new approach for predicting congestion using probabilistic method, and controlling congestion using new rate control methods. The probabilistic approach used for the prediction of occurrence of congestion in a node is developed using data traffic and buffer occupancy. The rate control method uses rate allocation schemes, namely, rate reduction (RR), rate regulation (RRG) and split protocol (SP) to improve throughput and to reduce packet drops. In addition, an energy-efficient routing which finds the best forwarding node for data transmission is also proposed. Simulation results are compared with decentralised predictive congestion control (DPCC). The results show that the proposed method indeed reduces congestion and energy consumption, and improves the performance.

This paper proposes a Payment Punishment Scheme (PPS) working along with various established models to encourage truth telling during election process of the nodes in a cluster, motivate individual nodes in a cluster to cooperate and stimulate the nodes to monitor and acknowledge the successful information interchanges between nodes and/or clusters. To prompt the creation of a robust cluster in a Vehicular Ad-hoc Network (VANET), vehicles with greater resources (weights) are elected as Cluster Heads after scrutinizing their advertised weights (using the VCG model). The vehicles are discouraged to provide willful wrong information by awarding them incentives called reputation, which upon accumulation secure a higher priority of information interchange for the vehicle. Each vehicle can increase their reputation by participating in election process, forwarding the data packets and monitoring and reporting the performance of other nodes by acting as watchdogs. A modified Extended Dempster-Shafer model is used to discourage one or more selfish and/or malicious nodes to effectively implement the PPS by using watchdogs, gateway nodes, etc. The proposed scheme has been analyzed with extensive experiments. The effectiveness of this method is compared with state-of-the-art QoS-OLSR protocol.

Vehicular communication is one of the fast growing and promising technologies for a safe and comfortab le driving environment. These technologies do not end up with economic and safety ramifications, but also extended with other informational and entertainment oriented services. Data are being propagated multi -hop between source and destination vehicles for many re al-life applications. Clustering is one of the effe ctive and scalable solutions for data dissemination in wirele ss ad hoc networks. Though many cluster-based methods have been proposed for multi-hop data delivery in v ehicular ad hoc networks, most of them do not consi der the real-time changes in the network topology or impose s large penalties in routing such as unstable clust ers, broken links, updating route tables. In order to ad dress these issues, we propose a broadcast based ro uting protocol for inter-cluster data dissemination in th is study that works on real-time vehicle informatio n. Unlike, most existing routing algorithms, it only uses hell o messages to obtain routing information without ma ny other control messages. In addition, it alleviates the st orage of routing information in every node, which l argely reduces the overheads in routing. We performed exte nsive simulation to demonstrate the effectiveness a nd efficiency of the proposed routing protocol. Result s show that the proposed protocol outperforms other approaches in terms of average delay, average deliv ery ratio and average number of hops.

Any node in a wireless sensor network is a resource constrained device in terms of memory, bandwidth, and energy, which leads to a large number of packet drops, low throughput, and significant waste of energy due to retransmission. This paper presents a new approach for predicting congestion using a probabilistic method and controlling congestion using new rate control methods. The probabilistic approach used for prediction of the occurrence of congestion in a node is developed using data traffic and buffer occupancy. The rate control method uses a back-off selection scheme and also rate allocation schemes, namely rate regulation (RRG) and split protocol (SP), to improve throughput and reduce packet drop. A back-off interval selection scheme is introduced in combination with rate reduction (RR) and RRG. The back-off interval selection scheme considers channel state and collision-free transmission to prevent congestion. Simulations were conducted and the results were compared with those of de- centralized predictive congestion control (DPCC) and adaptive duty-cycle based congestion control (ADCC). The results showed that the proposed method reduces congestion and improves performance.

Improving road safety and optimizing road traffic relies on both Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications. The successful deployment of vehicular communication depends on the two contentious factors, security and privacy. Though several researches have been conducted on the issuance of pseudonyms to deal with these issues, the traditional PKI based schemes used for the generation of these pseudonyms produce an enormous signing and verification costs. In order to address this problem, we propose a novel scheme in which the RSUs in a VANET use a one-way hash chain scheme to generate a series of public/private key pairs and to distribute them along with an n bit hash code H@^ and a proof cipher C@^ to the vehicles in its range. Since the RSU will provide a synchronized clock to all vehicles, anytime a vehicle can verify another vehicle by combining the vehicle's public key and its n bit hash code, which should prove the same cryptographic hash function of the receiving vehicle. Through this proposed Hash-chain based Authentication Protocol (HAP), the certificate costs of messages are immensely reduced. Moreover, if an attacker tries to compromise a node's public key it will be infeasible for him/her to achieve the desired task, as the vehicle frequently changes its public/private keys in a random fashion and hence guarantees a secured vehicle communication. We analyzed the proposed protocol extensively to validate its better performance when compared to its counterparts.

Obtaining efficient security without compromising p rivacy is a primary issue in vehicular communicatio n. Though many counterparts proposed solutions in this regard, accommodating scalability, security and traceability altogether is a difficult task due to the contradictions between these qualities. Some of the previous studies suggests RSU based authentication to address the above issues, while others propose independent OBU authentication. In either scheme, a ny one of the entities is overloaded during key generation and verification processes. The proposed scheme addresses these issues, by distributing the workload between OBUs and RSUs to outperform other protocols. We propose a novel scheme, in which OBUs generate short-lived public keys on the fly an d other vehicles can verify them with the help of R SUs. This protocol also admits certificate-less authenti cation, in addition to aggregated signature verific ation. Therefore, the total verification time can be drast ically reduced in the proposed scheme. We analyze t he proposed protocol significantly to demonstrate its efficiency.

Mobile devices play a vital role in our day to day life. The various sensing modalities available in mobile devices are identified and justify the growth of the capabilities on today’s smart phones.Taking advantage of the sensing capabilities of the mobile devices paves way for a new era of network, referred as people centric sensing network. In this paper, a broad study about the applications, architectural components and the existing privacy and security architectures available are discussed. The applications of mobile sensing are categorized as personal, social and public sensing based on what they sense, how they share and infer. All these applications clearly depict the roles played by people. People may act as end users, as participants and as application administrators. Since people are in the loop, the basic privacy and security requirements are analyzed that can be realized as the need in the design of any mobile phone sensing systems. The possible threats that arise in this sensing context may be due to both internal and external entities. The strategies and types of adversarial models in the people centric sensing approach provides us light to how the framework works and solutions needed. Existing literature in terms of privacy preserving data aggregation schemes and security Frameworks are also discussed in detail. Applications: The model clearly portraits the importance of people who are no more only passive data users. More focus has to be given on privacy preserving models to make the system more acceptable by the people.

Background: The technological advances in mobile and wireless communication have paved way for a new era of large scale sensing network. Smart phones used by people are nowadays equipped with rich set of sensing capabilities. These mobile devices carried by people can be used together to form a network called people centric sensing network. Methods: Since people are the mobile custodians, privacy becomes a threat to the network. This paper focuses on a study about the various privacy preserving aggregation schemes existing in other domains of the wireless network including people centric sensing. The design goals and challenges that arise when attempting to protect the user’s sensitive data are analyzed. The techniques commonly used to achieve user’s privacy are the homomorphic property of encryption schemes, Data slicing and Mix schemes. Findings: A study about the existing privacy preserving aggregation schemes enables us to design a new method that is more suitable for people centric sensing network. The design considerations involved in developing a security and privacy framework are also identified. The privacy preserving aggregation scheme should support spatial and temporal aggregation with fault tolerance. The scheme has to be adaptable for both additive and non-additive statistical aggregation functions. Also maintaining the data integrity, data privacy and data accuracy with less computational and communication overhead is essential. Applications: Privacy protection is important for user’s participation which supports large set of cooperative sensing applications. Irrespective of various domains in wireless networks, the privacy preserving data aggregation model is discussed that is suitable for the context of the applications.

A wireless sensor network (WSN) is a one made up of small sensing devices equipped with processors, memory, and short-range wireless communication. Sensor nodes, are autonomous nodes, which include smart dust sensors, motes and so on. They co-operatively monitor physical or environmental conditions and send the sensed data to the sink node. They differ from traditional computer networks due to resource constraints, unbalanced mixture traffic, data redundancy, network dynamics, and energy balance. These kinds of networks support a wide range of applications that have strong requirements to reduce end-to-end delay and losses during data transmissions. When large numbers of sensors are deployed in a sensor field and are active in transmitting the data, there is a possibility of congestion. Congestion may occur due to buffer overflow, channel contention, packet collision, a high data rate, many to one nature, and so on. This leads to packet loss which causes a decrease in throughput and lifetime. Maximum throughput, energy efficiency and minimum error rate can be achieved by minimizing the congestion. A number of quality of service (QoS) techniques has been developed to improve the quality of the network. This article gives an overview of existing QoS techniques and a parametric comparison made with recent developments. This article mainly concentrates on network congestion in WSN environment.

The reduction of dichloroethane (DCE) and trichloroethylene (TCE) by bimetallic iron–nickel (Fe–Ni) nanoparticles has been studied in this study. The reduction mechanism involves hydrodechlorinatio...

The Infrared spectra of carbohydrazide, diprotonated carbohydrazide and their deuterated compounds have been measured in the solid state. From the results on thio- and selenocarbohydrazides and other related molecules and normal coordinate analyses using a Urey-Bradley force field assignments of the fundamental vibrational frequencies and a description of the normal modes of carbohydrazide, diprotonated carbohydrazide and their deuterated species are given.

The routing problems can be divided into two major classes. They are 1) Unicast routing and 2) Multicast routing. The Unicast routing problem is as follows. Given a source node sr, a destination node dn, a set of QoS constraints qc and an optimization goal (optional), find the best feasible path from sr to dn, which satisfies qc. The Multicast routing problem is as follows. Given a source node sr, a set st of destination nodes, a set of constraints cts and an optimization goal (optional), find the best feasible path covering sr and all nodes in st, which satisfies cts. This article presents two such Unicast QoS based algorithms called as Source Routing and the proposed Heuristic Routing. A Client Server based model has been generated to study the performance of the two algorithms with respect to the message overhead, response time and path delay. The Experiments and the results are analyzed.

Diamond-like carbon nanostructures were prepared using Plasma enhanced chemical vapor deposition (PECVD). Temperature dependence of self-assembly of carbon nanostructures is noted. Carbon and silicon exhibit significant lattice mismatch and during the self-assembly, stacking of carbon atoms takes place which results in conic projections. The carbon nanostructures were prepared at 600°C and 100 W RF power and were subjected to a cooling treatment. Argon and Methane were used as reactant gases. The formation of nanostructures did not use any catalyst. The surface morphology and roughness analysis was carried by Atomic Force microscopy. The nanocones were characterized by X Ray Diffractometer and Raman Spectroscopy.

In this work, chair like fully hydrogenated germanane (CGeH) nano-ribbon 6 nm short channel double gate field effect transistor (DG-FET) has been modeled and the impact of strain on the I–V characteristics of CGeH channel has been examined. The bond lengths, binding and formation energies of various hydrogenated geometries of buckled germanane channel were calculated using local density approximation (LDA) with Perdew–Zunger (PZ) and generalized gradient approximation (GGA) with Perdew Burke Ernzerhof (PBE) parameterization. From four various geometries, chair like structure is found to be more stable compared to boat like obtuse, stiruup structure and table like structure. The bandgap versus width, bandgap versus strain characteristics and I–V characteristics had been analyzed at room temperature using density functional theory (DFT). Using self consistent calculation it was observed that the electronic properties of nano-ribbon is independent of length and band structure, but dependent on edge type, strain [Uni-axial (e xx ), bi-axial (e xx = e yy )] and width of the ribbon. The strain engineered hydrogenated germanane (GeH) showed wide direct bandgap (2.3 eV) which could help to build low noise electronic devices that operates at high frequencies. The observed bi-axial compression has high impact on the device transport characteristics with peak to valley ratio (PVR) of 2.14 and 380% increase in peak current compared to pristine CGeH device. The observed strain in CGeH DG-FET could facilitate in designing novel multiple-logic memory devices due to multiple negative differential resistance (NDR) regions.

The problem of word search in Sanskrit is inseparab le from complexities that include those caused by euphonic conjunctions and case-inflections. The cas e-inflectional forms of a noun normally number 24 owing to the fact that in Sanskrit there are eight cases and three numbers-singular, dual and plural. The traditional method of generating these inflectional forms is rather elaborate owing to the fact that t here are differences in the forms generated between even very similar words and there are subtle nuances involved. Further, it would be a cumbersome exercis e to generate and search for 24 forms of a word during a word search in a large text, using the cur rently available case-inflectional form generators. This study presents a new approach to generating ca se-inflectional forms that is simpler to compute. Further, an optimized model that is sufficient for generating only those word forms that are required in a word search and is more than 80% efficient compar ed to the complete case-inflectional forms generator, is presented in this study for the first time.

Power consumption plays crucial role in wireless sensor network (WSN). WSN is widely used for many applications in industries, military, home monitoring system etc. Data is sensed, manipulated and transmitted to the next hop nodes. Finally it reaches the destination. Certain amount of battery power is consumed by the sensor node for transmitting, receiving, listening and sleeping. In order to utilize the battery power efficiently we developed a technique which finds suitable forwarding node for transmission. The forwarding node is found based on the power level of the transmitter node. The forwarding node is chosen so that the distance to the destination is minimum compared to other neighbor nodes of the transmitter node. Moreover, energy in WSN is wasted due to packet retransmission. Network congestion is one of the primary reasons for packet drop which leads to packet retransmission. Therefore in addition to the energy efficient model, congestion control method is also proposed. Suitable outgoing rate is selected for every node in order to reduce congestion. Simulation results are compared with existing protocols and show improvement.

In the previous chapter, we discussed the distinct characteristics of ad hoc networks, which make them very difficult to secure. Such characteristics include: the lack of network infrastructure; no pre-existing relationships; unreliable multi-hop communication channels; resource limitation; and node mobility. We provided a theoretical background to mobile ad hoc networks and the security issues that are related to such networks. We defined the ad hoc networks and their characteristics in terms of trust establishment. As the focus of the two chapters is on the network layer, attacks specific to this layer are identified and explained in Chapter 1. We also presented a survey of the existing key management solutions for mobile ad hoc networks. The current chapter is a continuation for the previous one. This is why we start this chapter by Section-2 that offers a survey of the existing secure routing protocols for mobile ad hoc networks. This section makes a pertinent observation that most secure routing protocols assume some kind of key management authority exists. Mobile ad hoc networks have little fixed network architecture and it is unlikely that there is a centralised authority member. Section-2 of this chapter together with last section of the previous one identify the problem that the two chapters together are addressing. There exists secure routing mechanisms to address the unique characteristics of mobile ad hoc networks, however, these solutions assume that key management is addressed prior to network establishment. A novel, ondemand solution to the key management problem for mobile ad hoc networks is then described. Section-3 details the functionality and operation of the proposed model: “Direct Indirect Trust Distribution” (DITD). The DITD model focuses on the task of distributing keying information. The DITD model also includes a verification optimization protocol and trust evaluation metric, which maximises the security of distribution. The implementation and simulation of the DITD model is examined in Section-4. There are various packages used to compare existing and proposed routing protocols. One such

Mobile ad hoc networks are complex wireless networks, which have little or no existing network infrastructure. These networks can be established in a spontaneous manner allowing organizations and network members to work together and communicate, without a fixed communication structure. The mobility, spontaneity and ad hoc nature of these networks makes them optimal solutions for disaster area communication and tactical military networks. Due to recent wireless technology advances, mobile devices are equipped with sufficient resources to realize implementation of these dynamic communication networks. However, for ad hoc networks to find a wide spread within both the military and commercial world, they must be secured against malicious attackers. Mobile ad hoc networks have distinct characteristics, which make them very difficult to secure. Such characteristics include: the lack of network infrastructure; no pre-existing relationships; unreliable multi-hop communication channels; resource limitation; and node mobility. Users cannot rely on an outside central authority, like a trusted third party (TTP) or certificate authority (CA), to perform security and network tasks. The responsibility of networking and security is distributed among the network participants. Users have no prior relationship with each other and do not share a common encryption key. Therefore, only after the network has been formed, the users establish trust and networking links. The establishment of networking links is identified as being vulnerable to security attacks. Trust establishment should allow protection for the network layer and ensure that honest links are created. The sporadic connectivity of the wireless links, inherent to mobile ad hoc networks, results in frequent link breakages. These characteristics introduce unique challenges to trust establishment. Both the routing and trust establishment protocols must be designed to handle the unreliable wireless communication channels: the dynamic topology changes and the distributive nature. The security solutions used for conventional wired networks cannot simply be applied to mobile ad hoc networks. More complex network management must be implemented to achieve trust establishment in mobile ad hoc networks. 8

In this paper, we propose a novel metric learning method based on regularized moving least squares. Unlike most previous metric learning methods which learn a global Mahalanobis distance, we define locally smooth metrics using local affine transformations which are more flexible. Experimental results provide empirical evidence for the effectiveness of our approach

The overlay approach has been widely used by many service providers for Traffic Engineering (TE) in large Internet backbones. In the overlay approach, logical connections are set up between edge nodes to form a full mesh virtual network on top of the physical topology. IP routing is then run over the virtual network. Traffic engineering objectives are achieved through carefully routing logical connections over the physical links. Although the overlay approach has been implemented in many operational networks, it has a number of well-known scaling issues. This paper proposes a new approach to achieve traffic engineering without full-mesh overlaying with the help of integrated approach and equal subset split method. Traffic engineering needs to determine the optimal routing of traffic over the existing network infrastructure by efficiently allocating resource in order to optimize traffic performance on an IP network. Even though constraint-based routing [1] of Multi-Protocol Label Switching (MPLS) is developed to address this need, since it is not widely tested or debugged, Internet Service Providers (ISPs) resort to TE methods under Open Shortest Path First (OSPF), which is the most commonly used intra-domain routing protocol. Determining OSPF link weights for optimal network performance is an NP-hard problem. As it is not possible to solve this problem, we present a subset split method to improve the efficiency and performance by minimizing the maximum link utilization in the network via a small number of link weight modifications. The results of this method are compared against results of MPLS architecture [9] and other heuristic methods., {"references":["","A. Chakrabarti and G. Manimaran, Reliability constrained routing in QoS networks, IEEE/ACM Trans. on Networking, vol. 13, no. 3, pp. 662-675, June 2005.","D. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, and J. McManus. ''Requirements for traffic engineering over MPLS'', Internet draft, IETF, April 1998, draft-awduche-mpls-traffic-eng-00.txt.","Yufei Wang, Zheng Wang and Leah Zhang ''Internet Traffic Engineering without full mesh overlaying'', Infocom, 2001.","J Moy, ''OSPF version 2'', Internet rfc'', IETF, May 1998, Technical report RFC 2328.","C. Villamizar, ''OSPF optimized multipath'', Internet draft, IETF, March 1998, draft-ietf-ospf-omp-00.txt.","B. Fortz and M. Thorup, ''Internet traffic engineering by optimizing OSPF weights'', Proceedings of INFOCOM'2000, March 2000.","D. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, and J. McManus. Requirements for traffic engineering over MPLS. IETF RFC 2702, September 1999.","Yufei Wang and Zheng Wang, ''Explicit routing algorithms for internet traffic engineering'', Proceedings of ICCCN'99, Sept 1999.","E. Rosen, A. Viswanathan, and R. Callon. Multiprotocol label switching architecture, IETF RFC 3031, Standards Track, January 2001.\n[10] A. Soule, A. Nucci, E. Leonardi, R. cruz and N. Taft, How to identify and estimate top largest OD flows in dynamic environment. In Proceedings of SIGMETRICS'04, pages 49-60. New York, June 2004.\n[11] CPLEX: Mathematical Problem Solver. http://www.cplex.com.\n[12] V. Chvatal, Linear Programming, W H Freeman and Company, 1983.\n[13] D.P Bertsekas and R.G.Gallager, Data Networks (2nd Edition), Printice Hall. pp 434.\n[14] Yuxi Li, Janelle Harms and Robert Holte ''A simple method for balancing network utilization and quality of routing'', Proceedings of ICCCN'05. Sept.2005."]}

In mobile ad hoc networks (MANET), the existing distributed intrusion detection systems (IDS) are not completely distributed in its design. Though the data is collected from the distributed nodes, IDS analyse them centrally. In this paper, we propose a distributed node level security monitoring system for detecting and isolating attackers in mobile ad hoc networks. In the traffic flow-monitoring phase, behaviour of neighbour node is monitored compared with the pattern table for abnormal behaviour. In trust estimation phase, global trust value is estimated for each node in the chosen path based on direct and indirect trust values. If the trust value of any node is below threshold value, the node will be authenticated using the secret sharing technique and data is rerouted towards alternate path for the attacked path. From the simulation results, we show that our proposed system performs better than the existing IDS systems for MANET.