Varying Number Of Nodes Research Articles

MultiS-Net: A high-capacity, packet-switched, multichannel, single-hop architecture and protocol for a local lightwave network

A variety of multichannel single-hop network architectures and protocols have recently been proposed to exploit the vast capacity of fiber-optics which can well exceed the maximum electronic speed limit. Our MultiS-Net proposal is a new multichannel, single-hop architecture and protocol for a local network which provides packet-switched services to a large number of users connected to a multichannel broadcast medium. A separate channel, called control channel, is established to coordinate data packet transmissions on the other channels (called data channels). To allow low network interfacing costs, each node.in MultiS-Net is only equipped with a single tunable transmitter and a single tunable receiver, both of which are responsible for data channel access as well as control channel access. Without a separate transmitter and a separate receiver dedicated to the control channel, a node cannot have global knowledge of the network status all the time. Hence, global reservation is infeasible here, and all previously proposed schemes with the same low-cost network interface as in MultiS-Net fail to achieve a system throughput as high as those achieved by global-reservation schemes. MultiS-Net successfully incorporates a simple medium access mechanism, which can also achieve high system throughput. In addition, MultiS-Net can accommodate a variable number of nodes as well as time-varying load; typically, however, the number of nodes may be much larger than the number of available data channels. We analyze the performance of MultiS-Net by first constructing a multidimensional Markov chain. Then, the equilibrium point analysis (EPA) technique is adopted to obtain the average data packet delay and system throughput, which are verified by simulation. Numerical results from both the analytical model and simulations are presented, and the impact of various parameters on the system performance is discussed. Nearly-full utilization of total data channel bandwidth can be achieved under proper configurations of system parameters.

Asynchronous reservation protocol for variable-sized messages in a WDM-based local network

In this paper, we propose and analyse an asynchronous reservation protocol for a very high-speed optical LAN using a passive star topology. Each node is equipped with a single tunable transmitter and a single tunable receiver, both of which are tunable over a range of wavelengths. A separate channel, called the control channel, is used to coordinate message transmissions on the other channels, called data channels. We consider random and idle selection schemes for the data channel selection strategy. The proposed protocol can efficiently support variable-sized messages. It is operated asynchronously, i.e. data channels are not slotted and the control channel is slotted with the size of a control packet. Also, the protocol is scalable, hence the network can accommodate a variable number of nodes. Any new node can join the network without network reinitialization. Moreover, with the protocol one can avoid destination conflicts. We analyse its performance by using the equilibrium point analysis (EPA) method, and validate the results by simulation. According to the numerical results, the asynchronous protocol achieves higher throughput than the synchronous one.

Embedded unidirectional incomplete hypercubes for optical networks

Many proposals of virtual regular topologies embedded in physical topologies for high-speed wavelength division multiplexing (WDM) optical networks do not consider the issue of allowing a variable number of nodes in the network. A solution for embedding a virtual unidirectional incomplete hypercube into a physical topology that does is presented. The proposed solution is a multichannel multihop network which has several elegant features: (a) it allows any number of nodes to be connected to the network, (b) it only requires a minor effort to reconfigure the new interconnection whenever a node is added or deleted for the network, (c) it supports a self-routing strategy, (d) the aggregate throughput of the network increases as more nodes are added, and (e) alternate paths are available which have a comparable distance to the destination as the primary path. The performance of the scheme is comparable to the performance of both the unidirectional hypercube and the bidirectional hypercube.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Solutions of a steady state free surface seepage problem on a Hypercube concurrent computer

The advantages of using a multi‐CPU concurrent computer in solving a steady state free surface seepage problem are studied. The underlying computational task is the solution of a large set of linear equations with a projection operation numerous times. In the study, both Jacobi and SOR iteration methods with projection in a modified alternating iteration scheme are used to solve the problem with varied number of nodes (CPUs) and the timing results are compared between a 32 node Hypercube Concurrent Computer and a VAX 11/780 (single CPU). In addition, the performance and the feasibility of the Hypercube Concurrent Computer are discussed by comparing with the number of nodes used and with the VAX 11/780.

SCHMIDTMAC—A program to display and analyze directional data

SCHMIDTMAC is a program to display orientation data on an equal-area projection. It has been developed in Pascal for use on a Apple Macintosh microcomputer; to make it user-friendly, extensive use has been made of the Macintosh graphic interface. It provides the main following facilities: (a) easy modification of a stereogram displayed on the screen, (b) possible identification (by clicking on a point, or by enclosing a group of points with a “lasso”) of displayed orientations, (c) calculation of orientation densities with a new grid, characterized by a variable number of nodes and apical angles of the counting cones, a net that allows variable smoothing of densities and “economic” counting and contouring algorithms, and (d) statistical estimations of, for example, the best axis or best plane for simple distributions, or automatic set-partitioning and the best axis of each set of more complex distributions.

Effect of varying node number per bearer on yield and juice composition of Cabernet Sauvignon grapevines

Cabernet Sauvignon vines were pruned so that bearers of varying node number ranging from 2-node spurs to 14-node canes were retained on the same vine. Studies of factors that determine production and grape juice composition were made. A linear relationship between yield per bearer and nodes per bearer was established, a result of more bunches from increased shoot numbers. Bunch weight and yield per node decreased linearly as node number per cane increased. The effect of node position along bearers on time of budburst, shoots per node and bunches per shoot were described with linear or higher order polynomial regressions for each treatment. Juice composition was largely unaffected by a 5-fold difference in yield between the pruning treatments.

Thermal Aalysis of Quench Propagation In Superconducting Coils

The transient three-dimensional conduction equation with a source term that accounts for the propagating resistive wave front has been solved for a superconducting magnet coil by the control volume finite-difference method with floating nodes. Coupled with this, the code solves the electrical and magnetic circuit equations. Because of the large number of nodes dictated by the geometric structure of the coil, an alternate direction implicit (ADI) technique was used to overcome the computer storage problem. The behavior of the propagating front and the highly nonlinear material properties limit the size of the solution time steps. A variable time step and variable number of nodes have been used to reduce the overall computational time. The results of the analysis are in excellent agreement with experimental data.