Failure Detection and Recovery in Hierarchical Network Using FTN Approach

In current scenario several commercial and social organizations are using computer networks for their business and management purposes. In order to meet the business requirements networks are also grow. The growth of network also promotes the handling capability of large networks because it counter raises the possibilities of various faults in the network. A fault in network degrades its performance by affecting parameters like throughput, delay, latency, reliability etc. In hierarchical network models any possibility of fault may collapse entire network. If a fault occurrence disables a device in hierarchical network then it may distresses all the devices underneath. Thus it affects entire networks performance. In this paper we propose Fault Tolerable hierarchical Network (FTN) approach as a solution to the problems of hierarchical networks. The proposed approach firstly detects possibilities of fault in the network and accordingly provides specific recovery mechanism. We have evaluated the performance of FTN approach in terms of delay and throughput of network.Comment: 8 pages, 7 figure. International Journal of Computer Science Issues, 201

Controlling Smart Matter

Smart matter consists of many sensors, computers and actuators embedded within materials. These microelectromechanical systems allow properties of the materials to be adjusted under program control. In this context, we study the behavior of several organizations for distributed control of unstable physical systems and show how a hierarchical organization is a reasonable compromise between rapid local responses with simple communication and the use of global knowledge. Using the properties of random matrices, we show that this holds not only in ideal situations but also when imperfections and delays are present in the system. We also introduce a new control organization, the multihierarchy, and show it is better than a hierarchy in achieving stability. The multihierarchy also has a position invariant response that can control disturbances at the appropriate scale and location.Comment: 27 pages, Latex, further info available at ftp://parcftp.xerox.com/pub/dynamics/multiagent.htm

Towards Self-organizing Bureaucracies

This paper proposes self-organization as a method to improve the efficiency and adaptability of bureaucracies and similar social systems. Bureaucracies are described as networks of agents, where the main design principle is to reduce local "friction" to increase local and global "satisfaction". Following this principle, solutions are proposed for improving communication within bureaucracies, sensing public satisfaction, dynamic modification of hierarchies, and contextualization of procedures. Each of these reduces friction between agents (internal or external), increasing the efficiency of bureaucracies. "Random agent networks" (RANs), novel computational models, are introduced to illustrate the benefits of self-organizing bureaucracies.Comment: 22 pages, 13 figures, related work at http://homepages.vub.ac.be/~cgershen/sos/ v2. Added section presenting "random agent networks" model and simulation result

Optimal Organizational Hierarchies: Source Coding: Disaster Relief

ulticasting is an important communication paradigm for enabling the dissemination of information selectively. This paper considers the problem of optimal secure multicasting in a communication network captured through a graph (optimal is in an interesting sense) and provides a doubly optimal solution using results from source coding. It is realized that the solution leads to optimal design (in a well defined optimality sense) of organizational hierarchies captured through a graph. In this effort two novel concepts : prefix free path, graph entropy are introduced. Some results of graph entropy are provided. Also some results on Kraft inequality are discussed. As an application Hierarchical Hybrid Communication Network is utilized as a model of structured Mobile Adhoc network for utility in Disaster Management. Several new research problems that naturally emanate from this research are summarized

Network Slicing in Fog Radio Access Networks: Issues and Challenges

Network slicing has been advocated by both academia and industry as a cost-efficient way to enable operators to provide networks on an as-a-service basis and meet the wide range of use cases that the fifth generation wireless network will serve. The existing works on network slicing are mainly targeted at the partition of the core network, and the prospect of network slicing in radio access networks should be jointly exploited. To solve this challenge, an enhanced network slicing in fog radio access networks (F-RANs), termed as access slicing, is proposed. This article comprehensively presents a novel architecture and related key techniques for access slicing in F-RANs. The proposed hierarchical architecture of access slicing consists of centralized orchestration layer and slice instance layer, which makes the access slicing adaptively implement in an convenient way. Meanwhile, key techniques and their corresponding solutions, including the radio and cache resource management, as well as the social-aware slicing, are presented. Open issues in terms of standardization developments and field trials are identified

Providing a way to create balance between reliability and delays in SDN networks by using the appropriate placement of controllers

Computer networks covered the entire world and a serious and new development has not formed for many years. But companies and consumer organizations complain about the failure to add new features to their networks and according to their need, like much of the works to be done automatically and they also like to develop and expand their networks on the software side so they do not need new expensive hardware for many of the activities and needs of their network. Analysis of the control layers and writing data in Software-Defined Network facilitate network management and accelerate innovation in network. In order to develop broad networks of SDN, often a large number controller is needed and located position of controllers in the SDN networks and can be raised as an important and basic issue in the field of SDN network and have impact on reliability of SDN networks. This paper focused on latency and reliability in SDN networks. The latency here means the delay in response to the request of data path that has a significant impact on network latency. In this paper it is shown that the number of controllers and their position can be effective on two measures; reliability and latency in SDN networks

An Evolutionary Approach for Optimizing Hierarchical Multi-Agent System Organization

It has been widely recognized that the performance of a multi-agent system is highly affected by its organization. A large scale system may have billions of possible ways of organization, which makes it impractical to find an optimal choice of organization using exhaustive search methods. In this paper, we propose a genetic algorithm aided optimization scheme for designing hierarchical structures of multi-agent systems. We introduce a novel algorithm, called the hierarchical genetic algorithm, in which hierarchical crossover with a repair strategy and mutation of small perturbation are used. The phenotypic hierarchical structure space is translated to the genome-like array representation space, which makes the algorithm genetic-operator-literate. A case study with 10 scenarios of a hierarchical information retrieval model is provided. Our experiments have shown that competitive baseline structures which lead to the optimal organization in terms of utility can be found by the proposed algorithm during the evolutionary search. Compared with the traditional genetic operators, the newly introduced operators produced better organizations of higher utility more consistently in a variety of test cases. The proposed algorithm extends of the search processes of the state-of-the-art multi-agent organization design methodologies, and is more computationally efficient in a large search space

Dynamics of center-periphery patterns in knowledge networks - the case of China's biotech science and technology system

Science and technology systems - and their epistemic communities - are usually hierarchical and composed of a number of strong, large, leading organizations, along with a number of smaller and less influential ones. Moreover, these hierarchical patterns have a spatial structure: the leading organizations are concentrated in a few places, creating a science and technology center, whereas the majority of locations are peripheral. In the example of biotech research in China, we found dynamic changes in center-periphery patterns. These results are based on a network analysis of evolving co-authorship networks from 2001 to 2009 that were built combining national and international databases. Therefore, our results are not only relevant for evaluating the spatial structure and dynamics in the Chinese biotech system and its integration into the global knowledge network, but also revive a discussion on persistence and processes of change in the systems theory for sciencebased industries.Comment: 23 pages, 4 figures, 2 table

A Fault Tolerant, Area Efficient Architecture for Shor's Factoring Algorithm

We optimize the area and latency of Shor's factoring while simultaneously improving fault tolerance through: (1) balancing the use of ancilla generators, (2) aggressive optimization of error correction, and (3) tuning the core adder circuits. Our custom CAD flow produces detailed layouts of the physical components and utilizes simulation to analyze circuits in terms of area, latency, and success probability. We introduce a metric, called ADCR, which is the probabilistic equivalent of the classic Area-Delay product. Our error correction optimization can reduce ADCR by an order of magnitude or more. Contrary to conventional wisdom, we show that the area of an optimized quantum circuit is not dominated exclusively by error correction. Further, our adder evaluation shows that quantum carry-lookahead adders (QCLA) beat ripple-carry adders in ADCR, despite being larger and more complex. We conclude with what we believe is one of most accurate estimates of the area and latency required for 1024-bit Shor's factorization: 7659 mm$^{2}$ for the smallest circuit and $6 * 10^8$ seconds for the fastest circuit.Comment: Appears in International Symposium on Computer Architecture 2009 (ISCA09

Organizational Fluidity and Sustainable Cooperation

We show that fluid organizations display higher levels of cooperation than attainable by groups with either a fixed social structure or lacking one altogether. By moving within the organization, individuals cause restructurings that facilitate cooperation. Computer experiments simulating fluid organizations faced with a social dilemma reveal a myriad of complex cooperative behaviors that result from the interplay between individual strategies and structural changes. Significantly, fluid organizations can display long cycles of sustained cooperation interrupted by short bursts of defection.Comment: 17 pages. Also available through anonymous ftp from parcftp.xerox.com in the directory /pub/dynamic