Number Of Network Configurations Research Articles

Optimal Coordination Of Multiple Setting Group Type Overcurrent Relays

Relay coordination optimization issues are multi-objective, multi-constrained problems that aim to reduce each relay's operation time while satisfying all relevant constraints. Fulfillment of the coordination time interval (CTI) and time limitations for relay operations are the coordination constraints. To solve coordination optimization issues, decision-making variables are defined such that the objective function is minimized with due satisfaction of necessary constraints. The majority of the most recent research that is currently available defines relay coordination for fixed network topologies, but in practice, it varies for a variety of reasons, including maintenance and element failures. Over current relays now have the capability of storing multiple relay settings but the number of relay settings that can be stored in relays is far less than the possible number of network configurations, which is why a suitable clustering technique such as K-Means can be used to cluster out various network topologies using a proper clustering index. Because both the objective function and the constraints are time dependent, time dependent attributes such as average relay operating time are used as the clustering index instead of the conventional index fault current deviation.

Test of Reconfigurable Modules in Scan Networks

Modern devices often include several embedded instruments, such as BIST interfaces, sensors, calibration facilities. New standards, such as IEEE Std 1687, provide vehicles to access these instruments. In approaches based on reconfigurable scan networks (RSNs), instruments are coupled with scan registers, connected into chains and interleaved with reconfigurable modules. Such modules embed reconfigurable multiplexers that permit a selective access to different parts of the chain. A similar scenario is also supported by IEEE Std 1149.1-2013. The test of permanent faults affecting an RSN requires to shift test vectors throughout a certain number of network configurations. This paper presents some methodologies to select the list of configurations that perform the complete test of the reconfigurable modules of the RSN. In particular, one method is presented that, by construction, can be proved to be able to apply the test in the minimum amount of clock cycles. Other methods are sub-optimal in terms of test application time (TAT), but scale well on large circuits. In order to provide a comparison between the proposed methods, experimental results on some benchmark RSNs are provided.

The dynamic shortest path problem with time-dependent stochastic disruptions

The dynamic shortest path problem with time-dependent stochastic disruptions consists of finding a route with a minimum expected travel time from an origin to a destination using both historical and real-time information. The problem is formulated as a discrete time finite horizon Markov decision process and it is solved by a hybrid Approximate Dynamic Programming (ADP) algorithm with a clustering approach using a deterministic lookahead policy and value function approximation. The algorithm is tested on a number of network configurations which represent different network sizes and disruption levels. Computational results reveal that the proposed hybrid ADP algorithm provides high quality solutions with a reduced computational effort.

Errors in estimating spherical harmonic coefficients from partially sampled GCM output

This study describes a method of calculating the mean squared error (MSE) incurred when estimating the spherical harmonic coefficients of a climatological field that is sampled at a small network of points. The method can also be applied to the coefficients of any other set of orthonormal basis functions that are defined on the sphere. It, therefore, provides a formalism that can be applied in a variety of contexts, such as in climate change detection, where inferences are attempted about fingerprint coefficients that are imperfectly estimated from observational data. By incorporating the fingerprint as part of a set of basis functions, the methodology can be used to estimate the sampling error in the fingerprint coefficient. The MSE is expressed in terms of the spherical harmonics (or other orthonormal expansion) of the empirical orthogonal functions (EOFs), the locations of the points in the network and a set of weights that are applied at these points. The weights are optimised by minimising the expected MSE. The method is applied to a number of network configurations using monthly-mean screen temperature and 500 mb height simulated by the Canadian Climate Centre 2nd generation general circulation model in an ensemble of six 10-year simulations. In comparison with uniform weighting, optimal weighting can reduce the MSE by an order of magnitude or more for some spherical harmonic coefficients and some network configurations. Also, the MSEs vary seasonally for each network. In particular, the relative MSE of low order spherical harmonic coefficients is found to be larger in DJF than in JJA. We demonstrate how MSEs improve with increasing network density and identify graphically, the coefficients that can be estimated reliably with each network configuration.

The networked video jukebox

The availability of low-cost compression/decompression (codec) hardware for video and audio has given us the opportunity to provide multi-media applications over data networks. The paper describes a particular system that the authors have built to demonstrate this capability. A video jukebox has been built using off-the-shelf computers connected over Ethernet. For wide area connectivity, SMDS attachment has been used. Combined video and audio clips can be selectively played on a PC equipped with low cost video and audio codec cards, using JPEG and ADPCM compression hardware. The data for these clips is retrieved in real time from a Unix workstation via the network. Following a description of the system design, the performance obtainable from a number of network configurations is shown from the results of the experiments conducted. These results show that the addition of real-time transport software on top of the standard Internet protocols allows one to provide video and audio clips with a system comprising standard off-the-shelf equipment. The quality of these clips is considered acceptable for many applications. The authors have quantified the capacity of the system in terms of the data rates and the number of users, and have identified which parts of the total system become bottlenecks as each of these parameters is increased. Solutions to overcoming these bottlenecks are described. >

Deflection Routing in Regular MNA Topologies

We introduce MNA (Multigrid Network Architecture) – a networking concept aimed at applications calling for very high transmission rates (of the order of gigabits per second). An MNA network is a collection of photonic switches linked by optical channels. A switch is responsible for relaying incoming packets along the best available routes to their destinations. Packets that cannot be relayed optimally are deflected, i.e., relayed along suboptimal paths. The technology for building MNA switches has been developed in Lockheed Palo Alto Research Lab, [20]-[22]. In this paper, we discuss the logical aspects of MNA, present a model for investigating the performance of MNA in regular topologies, and apply this model to a number of network configurations.