Role of connectivity in congestion and decongestion in networks

We study network traffic dynamics in a two dimensional communication network with regular nodes and hubs. If the network experiences heavy message traffic, congestion occurs due to finite capacity of the nodes. We discuss strategies to manipulate hub capacity and hub connections to relieve congestion and define a coefficient of betweenness centrality (CBC), a direct measure of network traffic, which is useful for identifying hubs which are most likely to cause congestion. The addition of assortative connections to hubs of high CBC relieves congestion very efficiently.Comment: 9 pages, 5 figures, the Proceedings of the 3rd International Conference NEXT-SigmaPh

The ultimate strength of statically indeterminate prestressed concrete structures

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Contributions To Multivariate Analysis Based On Elliptic T Model

Theoretical developments in multivariate analysis are primarily based on the assumption of multivariate normality and very little is known for other cases. The aim of the present work is to generalize results of multivariate analysis based on a class of elliptic distributions, more specifically the subclass of the multivariate t-distributions with suitable parameters, rather than the usual normality assumption. The multivariate normal distribution belongs to the class of elliptic as well as the subclass of t-distribution.;The major contributions of the thesis are: (a) An elliptic set-up for uncorrelated samples is proposed. (b) The distributions of sample mean and covariance matrix are derived. (c) Classification problem is studied for the elliptic set-up.;The elliptic class is further specialized to a subclass of multivariate t-distributions, whose characteristic function, conditional distributions etc. are derived. Also the above problems (b) and (c) are studied. In addition the following problems have been solved: (i) null and non-null distributions of quadratic forms (analogue of non-central chi-square). (ii) estimation of location, scale and degrees of freedom parameters of the t-distribution and the sampling properties of the estimators. (iii) orthogonal factor analysis when both observed error and unobserved factors follow multivariate t-distributions. (iv) estimation of parameters and testing of hypothesis for a regression model with error variable having a multivariate t-distribution

Feedback based real-time MAC (RT-MAC) protocol for data packet streaming in wireless sensor networks

Wireless sensor networks (WSNs) are generally used for event driven monitoring or periodic reporting. Once a triggering event happens, it needs to be reported in real-time as a continuous stream for some duration. In order to address such communication requirements, this thesis introduces a soft Real-Time MAC (RT-MAC) protocol for real-time data packet streaming in wireless sensor networks. RT-MAC eliminates contention for a wireless medium by introducing a feedback control packet, called Clear Channel (CC). As a result, RT-MAC has a consistent and predictable data transmission pattern that provides end-to-end delay guarantees. Additionally, RT-MAC has a lower end-to-end delay than other real-time WSN MAC protocols for two reasons: (1) it maximizes spatial channel reuse by avoiding the false blocking problem caused by request-to-send (RTS) and clear-to-send (CTS) exchanges in wireless MAC protocols (2) it reduces contention duration of control packets to facilitate faster data packet transfer. Thus, RT-MAC facilitates periodic data packet deliveries as well as alarming event reporting. RT-MAC operates both with and without duty cycle mode (sleep/wakeup schedule for sensor nodes). Duty cycle mode of RT-MAC is useful in situations where energy conservation is one of the goals along with real-time requirements. RT-MAC is well suited for multi-hop communication with a large number of hops. RT-MAC protocol supports single-stream communication between a randomly selected source and sink node pair as well as multi-stream communication among different source and sink node pairs. This thesis provides the lower and upper end-to-end delay bounds for data packets transfer in normal mode of operation of RT-MAC protocol. We used state diagram analysis to show the in-depth functioning of RT-MAC protocol. This thesis also presents Markov analysis of RT-MAC that shows the behavior of the protocol in fault scenarios. Extensive simulation results are also presented in this thesis. These results show significant improvement in delay, packet throughput performance, and uniformity in packet transmission pattern at a cost of a very small increase in energy consumption as compared to other real-time MAC protocols such as VTS and general purpose MAC protocols such as S-MAC and T-MAC

Composition and combination‐based object trust evaluation for knowledge management in virtual organizations

Purpose – This paper aims to develop a framework for object trust evaluation and related object trust principles to facilitate knowledge management in a virtual organization. It proposes systematic methods to quantify the trust of an object and defines the concept of object trust management. The study aims to expand the domain of subject trust to object trust evaluation in terms of whether an object is correct and accurate in expressing a topic or issue and whether the object is secure and safe to execute (in the case of an executable program). By providing theoretical and empirical insights about object trust composition and combination, this research facilitates better knowledge identification, creation, evaluation, and distribution. Design/methodology/approach This paper presents two object trust principles – trust composition and trust combination. These principles provide formal methodologies and guidelines to assess whether an object has the required level of quality and security features (hence it is trustworthy). The paper uses a component‐based approach to evaluate the quality and security of an object. Formal approaches and algorithms have been developed to assess the trustworthiness of an object in different cases. Findings The paper provides qualitative and quantitative analysis about how object trust can be composed and combined. Novel mechanisms have been developed to help users evaluate the quality and security features of available objects. Originality/value This effort fulfills an identified need to address the challenging issue of evaluating the trustworthiness of an object (e.g. a software program, a file, or other type of knowledge element) in a loosely‐coupled system such as a virtual organization. It is the first of its kind to formally define object trust management and study object trust evaluation

Common Fixed Point Theorems for Four Self Maps on A Menger Space, Satisfying Common E. A. Property

In this paper, we prove common fixed point theorems for four self maps by using weak compatibility in Menger spaces. Our result extend, generalized several fixed point theorems on Menger spaces. Keywords— Common fixed points, Metric space, Menger space, weak compatible mappings and E. A. property. AMS subject classification– 47H10, 54H25

The inherent occurrence of complex intron-rich spliceosomal split genes, including regulatory and splicing elements, within pre-biotic random genetic sequences

Growing evidence indicates that complex intron-rich split genes and an advanced spliceosome existed in the earliest eukaryote, and possibly the first life form. We sought to examine how these split genes could have originated in the prebiotic system. We previously found that split coding sequences for complex proteins occur in abundance in random DNA sequences (P. Senapathy, et al, accompanying paper). This study demonstrates that a full complement of exons, introns and regulatory and splicing elements could have also occurred inherently within pre-biotic chemistry by chance. By comparing the characteristics of split genes found in computer-generated random genetic sequences with those of several extant eukaryotes, we show that an abundance of intron-rich split genes akin to those present in modern eukaryotes could have existed in the prebiotic system. These findings answer the post-genomic question of why the earliest life form contained highly complex intron-rich split genes, and, in conjunction with our companion study, show how they could encode a complex spliceosome