In this work, we have considered designing a highly efficient capacity-constrained overlay multicast protocol; it is designed specifically for an existing Chinese Remainder Theorem (CRT) - based structured P2P architecture [9]. Such an architecture has been the choice for its structural advantages over DHT-based architectures. It is worth mentioning its most important advantage from the viewpoint of speed of communication, that is its diameter, which is only 3 overlay hops. The protocol is not restricted to a single data source and it incorporates peer heterogeneity as well. We have also designed another any source capacity-constrained multicast protocol that incorporates the unique idea of transforming the multicast problem to a broadcast one [10]. We have compared analytically the performance of the two protocols; it has led to the observation that use of this unique idea [10] cannot take advantage of all structural advantages of a CRT-based system resulting in decrease in performance. However, the proposed multicast source discovery protocol has used this unique idea offering good performance.

In this work, we have considered a new hierarchical non-DHT based architecture for Peer-to-Peer (P2P) networks in which at each level of the hierarchy existing networks are all structured and each such network has the diameter of l overlay hop. Such low diameters have immense importance in designing very efficient data lookup algorithms. The mathematical model based on the Chinese Remainder Theorem has been used to define the neighborhood relations among peers to obtain the above-mentioned diameters. In this work, we present very efficient intra-group as well as inter-group data look up algorithms with O (1) time complexity exploiting the above mentioned low diameter features of the P2P system. Besides, we present very efficient algorithms related to peers joining with new and existing resource types.

Multicasting can be done in two different ways: source based tree approach and shared tree approach. Shared tree approach is preferred over source-based tree approach because in the later construction of minimum cost tree per source is needed unlike a single shared tree in the former approach. However, in shared tree approach a single core needs to handle the entire traffic load resulting in degraded multicast performance. Besides, it also suffers from `single point failure'. In this paper, novel and efficient schemes for load shared multicore multicasting are presented. Multiple cores are selected statically, that is, independent of any existing multicast groups and also the selection process is independent of any underlying unicast protocol. Some of the selected cores can be used for fault-tolerant purpose also to guard against any possible core failures.

Reverse Path Forwarding based multicasting used in Distance Vector Multicast Routing Protocol (DVMRP) has the major drawback of generating large number of duplicate and prune packets. Use of the concept of pseudo diameter reduces the number of duplicate packets. The reason is that pseudo diameter helps in the reduction of the scope of travel of a packet. In this work a new approach of multicasting with security has been proposed. The concept of pseudo diameter has been extended to further reduce the scope of travel of a packet. Use of this new concept known as super pseudo diameter while multicasting results in significant reduction of the number of prune packets generated; hence, it guarantees even better utilization of network bandwidth.

In this paper, we have considered a recently reported non-DHT based structured P2P system. The architecture is based on Linear Diophantine Equation (LDE) and it is an interest-based system; it offers very efficient data lookup. However, the architecture is restricted in that a peer cannot possess more than one distinct resource type. This may reduce the scope of its application. In this paper, we have extended the work by considering a generalization of the architecture, that is, a peer can possess multiple distinct resource types. We have proposed an efficient data lookup algorithm with time complexity bounded by (2+r/2); r is the number of distinct resource types. We have discussed about an alternative lookup scheme that needs constant number of hops and constant number of message exchanges. Besides, churn handling and ring maintenance have been shown to be very efficient.

This study aims to optimize patient flow in emergency departments (ED) while minimizing associated costs. In order to compare the effects of the optimization, a simulation model for emergency departments has been implemented using District Event Simulation (DES) and queuing theory, while for the optimization, Genetic Algorithm is used to find the best arrangements. Principally, a discrete event based, multi-class, multi-server queuing network is designed considering the emergency department as a set of stages each associated with a queue of patients waiting to be served. Each stage has multiple service providers such as Nurses, Doctors or other staff. We also classified patients passing through the stages according to their acuity level and personal characteristics. Then, a function is defined to measure the ED performance in respect to the calculated wait times and the cost. Finally, a customized genetic algorithm was developed to discover the best performance which reflects the best allocation of service providers to the different stages of the emergency department.

In this paper, we present a new approach to designing a scalable, hierarchical overlay P2P system which provides highly efficient data lookup operations as well fault tolerance. Instead of using a distributed hash table (DHT) based approach, we propose the use of Linear Diophantine Equation (LDE) as the mathematical basis to realize a hierarchical P2P architecture. LDE provides a significantly lighter weight mechanism to create and maintain the overlaid P2P structure as compared to DHT based schemes. To the best of our knowledge, ours is the first work that proposes the use of LDEs in designing P2P topologies. In our proposed hierarchical P2P architecture, the number of hops required to search for a resource is independent of the number of nodes/peers in the network n and is instead bounded by (1 + r/2), r being the number of distinct resource types. For most practical purposes, r is significantly smaller than n and hence our proposed architecture provides a highly efficient resource look-up procedure. We have also presented algorithms for handling of new resources and peers joining and leaving the P2P network and fault tolerance in the event of peers crashing or leaving.

Some of the attractive features of using Reverse Path Forwarding (RPF) method for broadcasting include reasonably low amount of memory necessary for storing the data structures in a router required by the protocol and ease of its implementation as it does not look for shortest path delivery. However, it generates quite a large number of duplicate packets resulting in poor bandwidth utilization. In this paper we have introduced a novel hierarchical pruning mechanism to improve bandwidth utilization for broadcasting using the RPF method. Experimental results support our theoretical findings of achieving very high reduction in the number of the duplicate packets generated.

In this paper, we have proposed a simple and efficient approach for recovery in distributed computing environment. The check pointing scheme used in the work ensures that after the system recovers from failures, all processes can restart from their respective recent checkpoints; thus avoiding any domino effect. That is, the recent check points always form a consistent recovery line. The recovery scheme deals with both orphan and lost messages. Therefore, correctness of computation of the underlying application program is guaranteed.

Model-based intrusion detection and knowledge discovery are combined to cluster and classify P2P botnet traffic and other malignant network activity by using a self-organizing map (som) self-trained on denied Internet firewall log entries. The SOM analyzed new firewall log entries in a case study to classify similar network activity, and discovered previously unknown local P2P bot traffic and other security issues.

Clustering algorithms are widely used methods for organizing data into useful information. The Competitive Agglomeration for Relational Data (CARD) Algorithm is one such clustering algorithm that is designed to organize user sessions into profiles, where each profile would highlight a particular type of user. The CARD algorithm is a viable candidate for Web clustering; however, it does have limitations such as an extended execution time. In addition, the methods that prepare the input data for the CARD algorithm's use employs concepts which seem to be incomplete. These limitations of the CARD algorithm are explored and modifications are introduced to yield a more practical and efficient algorithm.

The important problem of recognizing a priori the class of Boolean functions which are never obtainable from a given combinational network under short circuit faults is almost unexplored, primarily due to lack of understanding of the functional and structural factors that influence the fault behavior in the network. In view of this, a new concept of impossible class of faulty functions (ICFF) is introduced in this correspondence. Several intriguing properties of ICFF are uncovered, namely, the undetectability of input bridging faults, the impossibility of the transformation of a fault free function Fo to a subset or superset of Fo, and to other functions belonging to the same P-and N-equivalence classes of Fo, etc. The closure amongst the fan-out-free and unate functions under bridging faults is investigated. The impact of ICFF on the testability of the network is also discussed.