Grid Network Topology Research Articles

Highly Selective and Sensitive Luminescence Turn-On-Based Sensing of Al(3+) Ions in Aqueous Medium Using a MOF with Free Functional Sites.

A new metal-organic framework [Co(OBA)(DATZ)0.5(H2O)] {OBA = 4,4'-oxybis(benzoic acid) and DATZ = 3,5-diamino-1,2,4-triazole}, 1, was synthesized by hydrothermal reaction. Single-crystal X-ray data of 1 confirmed two-dimensional rhombus grid network topology with a free nitrogen site of triazole ring and two amine groups of each DATZ. Photoluminescence study of 1 in aqueous medium shows blue emission at 407 nm upon excitation at 283 nm. This emissive property was used for the sensing of Al(3+) ions in aqueous medium through very high luminescence turn-on (6.3-fold) along with the blue shifting (∼24 nm) of the emission peak. However, luminescence studies in the presence of other common metal ions such as Mg(2+), Zn(2+), Ni(2+), Co(2+), Mn(2+), K(+), Na(+), Ca(2+), Cd(2+), Hg(2+), Cu(2+), Fe(2+), Fe(3+), and Cr(3+) in aqueous medium shows luminescence quenching in varying extent. Interestingly, the luminescence turn-on-based selectivity of Al(3+) ions in aqueous medium was achieved even in the presence of the highest quenchable metal ion, Fe(3+). Furthermore, very high sensitivity was observed in the case of Al(3+) ions with a limit of detection of Al(3+) of 57.5 ppb, which is significantly lower than the higher limit of U.S. Environmental Protection Agency recommendation of Al(3+) ion for drinking water (200 ppb).

Evaluating Content-centric Communication Over Power Line Communication Infrastructure for Smart Grids

Abstract Electricity management systems are being in the center of a major research effort aiming at developing its new generation known as SMART GRID. The novelty in smart grids is a two-way data flow added on top of the classic electricity flow. This information traffic is the reason behind the smartness of the new power management system qualified to be more efficient, more secure and more reliable than its predecessor. In consequence, well-tailored communication architecture with particular necessary characteristics for smart grids is needed. Our motivation behind this work is to assess the adequacy of an emergent communication paradigm referred to as content-centric networking to smart grids. Our first contribution is confronting smart grid communication system requirements with content-centric networking principles in order to theoretically justify our position. Our second contribution is a simulation of smart grid communications using smart grid network topology and data traffic. A content-centric communication solution is deployed to achieve data networking and is compared to the Internet protocol stack allowing us to witness packet delivery delay reduction and better congestion control ability in addition to an increased throughput.

Performance Estimation of Static Grid Octagonal Topology under Distributed Environment through Simulation Tool

In the recent year, distributed computing systems are one of most efficient and a very popular approach of computing as compared to the old centralized computing systems. Such network processing environment provides a very high performance computing in a very low cost. Once such computing implemented in proposed topological architecture for static interconnection, achieves the desired accuracy. The present work is an attempt to measure the performance of different types of traffic such as video conferencing, file transfer as well as email service through the newly proposed octagonal topology. An application of the OPNET simulation tool is executed using packets transmission through octagonal grid network topology. Analysis of different types of applications packets has been done in the present work and study has been represented using graphs.

Mobility Impact on MANET Routing Protocols In Grid Networks

Mobile Ad-Hoc Networks (MANETS) is a collection of wireless mobile nodes that are able to dynamically form a temporary network without any aid from fixed infrastructure or centralized administration due to no wired backbone.Ad Hoc networks are formed spontaneously and the nodes are highly mobile.Thispaper presents performance evaluations, comparisons, andanalysis for three routing protocols (AODV, DSR, and OLSR)to bring out their relative meritsundervarying network size and mobilitywith  various speed and pause times. The simulation is carried out using OMNET++ simulator based on the quantitative basic parameters like throughput, Packet transmission Ratio (PTR),packet transmission time delay and protocol overhead .The  nodes are distributed randomly in a grid network topology and mobile nodes moving using Random Waypoint mobility models. The results demonstrate that, undervarious node speeds and pause timesfor different network size, AODVoutperforms DSR and OLSR protocols, with respect to networkthroughput (by 0.9% and 4.4%, respectively). For protocoloverhead,DSR has lower overhead than both AODV and OLSR protocols (by 13.4% and 65.5%, respectively). In contrast, thepacket transmission time delay when using OLSR is shorter than whenusing both AODV (by 81.7%) and DSR (by 76.7%).Â

Analysis of Power Sharing and Voltage Deviations in Droop-Controlled DC Grids

This paper analyzes the influence of the converter droop settings and the dc grid network topology on the power sharing in a dc grid based on voltage source converter high voltage direct current technology. The paper presents an analytical tool to study the effect of the droop control settings on the steady-state voltage deviations and power sharing after a converter outage, thereby accounting for dc grid behavior. Furthermore, an optimization algorithm is developed, taking into account two conflicting optimization criteria. The simulation results show that, when selecting appropriate values for the converter gains, a tradeoff has to be made between the power sharing and the maximum allowable dc voltage deviation after an outage.

Dynamically Changing the Symmetric Encryption Algorithm for Improving Security and Performance during Data Transfer in Grid Networks

In grid design authentication, authorization and confidentiality of the communication between computers are important security requirements. Without the functionality, the integrity and confidentiality of the data processed, the grid would be at risk. There are many different tools and technologies, which are available to ensure secured grid environment. The symmetric and asymmetric encryption algorithms are commonly used algorithms in grid software to provide necessary security, even though symmetric encryption algorithm significantly will affect the network communication performance. The previous work relied on the use of encryption and decryption at the application layer has an impact on the application layer performance and in the network layer performance. In the proposed work, instead of using a single encryption algorithm different encryption algorithms were selected arbitrarily during processing of each packet. The performance has been measured through simulation studies on NS2 by simulating these algorithms on GARUDA Grid Network Topology.

Synthesis and Magnetic Properties of Dual-Ligand Divalent Copper Coordination Polymers with Rhomboid Layer, Archimedean Grid, and Self-Penetrated Network Topologies

Four divalent copper coordination polymers containing both 1,2-phenylenediacetate (1,2-phda) and dipyridyl-type coligands have been prepared and structurally characterized by single-crystal X-ray diffraction. {[Cu(1,2-phda)(dpa)]·H2O}n (1, dpa = 4,4′-dipyridylamine) possesses a simple (4,4) rhomboid polymeric grid structure but can be considered a (4,6)-connected binodal supramolecular lattice with (4462)(446108) fsc topology. Use of a longer dipyridyl ligand afforded [Cu2(1,2-phda)2(dpp)]n (2, dpp = 1,3-di(4-pyridyl)propane), which manifests a rare self-penetrated rob lattice (48668 topology) built from the linkage of copper dicarboxylate layers through crossed dpp tethers. [Cu(1,2-phda)(H2O)(4-bpmp)0.5]n (3, 4-bpmp = bis(4-pyridylmethyl)piperazine) forms a 5-connected Archimedean cem layer with 334453 topology. The topology of 3 can be alternately described as a 3,4-connected binodal layer with a V2O5-type network. Incorporation of nitrate counterions led to formation of {[Cu(1,2-phda)(H2O)(H4-bpmp)] (N...

Improved Algorithms for Data-Gathering Time in Sensor Networks II: Ring, Tree, and Grid Topologies

We address the problem of gathering information in sensor webs consisting of sensors nodes, wherein a round of communication sensor nodes have messages to be sent to a distant central node (called the base station) over the shortest path. There is a wide range of data gathering applications like target and hazard detection, environmental monitoring, battlefield surveillance, etc. Consequently, efficient data collection solutions are needed to improve the performance of the network. In this article, we take into account the fact that interference can occur at the reception of a message at the receiver sensor. In order to save redundant retransmissions and energy, we assume a known distribution of sources (each node wants to transmit at most one packet) and one common destination. We provide a number of scheduling algorithms jointly minimizing both the completion time and the average packet delivery time. We define our network model using directional antennas and consider Ring, Tree, and Grid Network (and its generality) topologies. All our algorithms run in low-polynomial time.

Achieving optimal data storage position in wireless sensor networks

Data storage in wireless sensor networks (WSNs) involves producers (such as sensor nodes) storing in storage positions a large amount of data which they have collected and consumers (e.g., base stations, users, and sensor nodes) then retrieving that data. When addressing this issue, previous work failed to utilize data rates and locations of multiple producers and consumers to determine optimal data storage positions to be communication cost-effective in a mesh network topology. In this paper, we first formalize the data storage problem into a one-to- one ( one producer and one consumer) model and a many-to- many ( m producers and n consumers) model with the goal of minimizing the total energy cost. Based on above models, we propose optimal data storage (ODS) algorithms that can produce global optimal data storage position in linear, grid, and mesh network topologies. To reduce the computation of ODS in the mesh network topology, we present a near-optimal data storage (NDS) algorithm, which is an approximation algorithm and can obtain a local optimal position. Both ODS and NDS are locality-aware and are able to adjust the storage position adaptively to minimize energy consumption. Simulation results show that NDS not only provides substantial cost benefit over centralized data storage (CDS) and geographic hash table (GHT), but performs as well as ODS in over 75% cases.

Energy-efficient cooperative routing in BER constrained multishop networks

Due to the limited energy supplies of nodes, in many applications like wireless sensor networks energy-efficiency is crucial for extending the lifetime of these networks. We study the routing problem for multihop wireless ad hoc networks based on cooperative transmission. The source node wants to transmit messages to a single destination. Other nodes in the network may operate as relay nodes. In this paper, we propose a cooperative multihop routing for the purpose of power savings, constrained on a required bit error rate (BER) at the destination. We derive analytical results for line and grid network topologies. It is shown that energy savings of 100% are achievable in line and grid networks with a large number of nodes for BER = 10−4 constraint at the destination.

Cooperative Routing in Static Wireless Networks

We study the problem of transmission-side diversity and routing in a static wireless network. It is assumed that each node in the network is equipped with a single omnidirectional antenna and that multiple nodes are allowed to coordinate their transmissions in order to obtain energy savings. We derive analytical results for achievable energy savings for both line and grid network topologies. It is shown that the energy savings of and are achievable in line and grid networks with a large number of nodes, respectively. We then develop a dynamic-programming-based algorithm for finding the optimal route in an arbitrary network, as well as suboptimal algorithms with polynomial complexity. We show through simulations that these algorithms can achieve average energy savings of about in random networks, as compared to the noncooperative schemes.

Distributed mutual exclusion algorithms for grid applications: A hierarchical approach

The majority of current distributed mutual exclusion algorithms are not suited for parallel or distributed applications on a Grid as they do not consider the heterogeneity of latency on Grids. We propose two distributed mutual exclusion algorithms, based on Naimi–Trehel's token-based algorithm, which take into account latency gaps, especially those between local and remote clusters of machines. Our first algorithm exploits cluster locality by giving higher priority to critical section requests issued from nodes of the same cluster when compared to those from remote nodes. Our second algorithm adds a router layer to the first algorithm, bringing it closer to Grid network topology. Viewing each cluster as a single node, the Naimi–Trehel algorithm is applied to this router layer. Redirection of inter-cluster messages to cluster's nodes is then minimized.

Channel assignment for interference avoidance in honeycomb wireless networks

The large development of wireless services and the scarcity of the usable frequencies require an efficient use of the radio spectrum which guarantees interference avoidance. The channel assignment problem (CAP) achieves this goal by partitioning the radio spectrum into disjoint channels, and assigning channels to the network base stations so as to avoid interference. On a flat region without geographical barriers and with uniform traffic load, the network base stations are usually placed according to a regular plane tessellation, while the channels are permanently assigned to the base stations. This paper considers the CAP problem on the honeycomb grid network topology, where the plane is tessellated by regular hexagons. Interference between two base stations at a given distance is avoided by forcing the channels assigned to such stations to be separated by a gap which is proportional to the distance between the stations. Under these assumptions, the CAP problem on honeycomb grids can be modeled as a suitable coloring problem. Formally, given a honeycomb grid G = ( V , E ) and a vector ( δ 1 , δ 2 , … , δ t ) of positive integers, an L ( δ 1 , δ 2 , … , δ t ) -coloring of G is a function f from the vertex set V to a set of nonnegative integers such that | f ( u ) - f ( v ) | ⩾ δ i , if d ( u , v ) = i , 1 ⩽ i ⩽ t , where d ( u , v ) is the distance (i.e. the minimum number of edges) between the vertices u and v . An optimal L ( δ 1 , δ 2 , … , δ t ) -coloring for G is one minimizing the largest used integer over all such colorings. This paper presents efficient algorithms for finding optimal L ( 2 , 1 ) -, L ( 2 , 1 2 ) - and L ( 1 t ) -colorings of honeycomb grids. Such colorings use less colors than those needed by the cellular and square grids with the same number of vertices.