On trading wavelengths with fibers: a cost-performance based study

We consider the effect of multiple fibers on wavelength division multiplexing networks without wavelength conversion. We study networks with dynamic wavelength routing and develop accurate analytical models to compare various possible options using single- and multiple-fiber networks. We use results of an analytical model and simulation-based studies to evaluate the blocking performance and cost of multifiber networks. The number of fibers required providing high performance in multifiber networks and their costs are compared. A case is made for using multiple fibers in each link with fewer wavelengths instead of using a single fiber with many wavelengths. In particular, we show that a network with four fibers per link and with four wavelengths on each fiber without any wavelength conversion on any node yields similar same performance as the networks with one fiber per link and 16 wavelengths per fiber on each link and with full wavelength conversion capability on all nodes. In addition, the multifiber network may also offer the cost advantage depending on the relative cost of components. We develop a parametric cost model to show that multiple fibers in each link are an attractive option. Finally, such multifiber networks also has fault tolerance, with respect to a single fiber failure, already built into the system.     

DISCREPANCIES IN THE REGRESSION MODELLING OF RECRYSTALLIZATION RATE AS USING THE DATA FROM PHYSICAL SIMULATION TESTS

The analysis of numerous experimental equations published in the literature reveals a wide scatter in the predictions for the static recrystallization kinetics of steels. The powers of the deformation variables, strain and strain rate, similarly as the power of the grain size vary in these equations. These differences are highlighted and the typical values are compared between torsion and compression tests. Potential errors in physical .simulation testing are discussed.     

Nanoclays for polymer nanocomposites, paints, inks, greases and cosmetics formulations, drug delivery vehicle and waste water treatment

An overview of nanoclays or organically modified layered silicates (organoclays) is presented with emphasis placed on the use of nanoclays as the reinforcement phase in polymer matrices for preparation of polymer/layered silicates nanocomposites, rheological modifier for paints, inks and greases, drug delivery vehicle for controlled release of therapeutic agents, and nanoclays for industrial waste water as well as potable water treatment to make further step into green environment. A little amount of nanoclay can alter the entire properties of polymers, paints, inks and greases to a great extent by dispersing 1nm thick layered silicate throughout the matrices. The flexibility of interlayer spacing of layered silicates accommodates therapeutic agents which can later on be released to damaged cell. Because the release of drugs in drug-intercalated layered materials is controllable, these new materials have a great potential as a delivery host in the pharmaceutical field. The problem of clean water can be solved by treating industrial and municipal waste water with organoclays in combination with other sorbents like activated carbon and alum. Organoclays have proven to be superior to any other water treatment technology in applications where the water to be treated contains substantial amounts of oil and grease or humic acid.     

Time and Space Optimal Data Parallel Volume Rendering Using Permutation Warping

In this paper we present a data parallel volume rendering algorithm that possesses numerous advantages over prior published solutions. Volume rendering is a three-dimensional graphics rendering algorithm that computes views of sampled medical and simulation data, but has been much slower than other graphics algorithms because of the data set sizes and the computational complexity. Our algorithm usespermutation warpingto achieve linear speedup (run time is O(S/P) forPprocessors whenP\= O(S/logS) forS\=n³samples), linear storage (O(S)) for large data sets, arbitrary view directions, and high-quality filters. We derived a new processor permutation assignment of five passes (our prior known solution was eight passes), and a new parallel compositing technique that is essential for scaling linearly on machines that have more processors than view rays to process (P>n²). We show a speedup of 15.7 for a 16k processor over a 1k processor MasPar MP-1 (16 is linear) and two frames/second with a 128³volume and trilinear view reconstruction. In addition, we demonstrate volume sizes of 256³, constant run time over angles 5 to 75°, filter quality comparisons, and communication congestion of just 19 to 29\%.     

Effect of solid polymer electrolyte on the sensitization of photocurrents in solid-state electrochemical cells using conducting polypyrrole

The effect of small concentration of methylene blue dye on photocurrents was studied in the solid-state photoelectrochemical cells fabricated using conducting polypyrrole-coated electrodes sandwiched with solid-polymer electrolyte, namely, polyvinylpyrrolidone with phosphoric acid. A maximum photosensitivity factor (S=I _l/I _d, where I _l is the photocurrent and I _d is the dark current) of the order of 5 is observed. The current–voltage (I–V) characteristics in such cells reveal that charge transport is mainly governed by the space charge effect. Comparison of the results presented in this paper with the ones we reported earlier [23] indicates that the matrix in which dye has been incorporated plays an important role in such sensitization processes. A matrix that can efficiently transport the photogenerated charge carriers is observed to be more suitable for such dye-sensitized devices.     

A Heuristic Approach to the Railroad Track Maintenance Scheduling Problem

Abstract: Every year, billions of dollars are spent on rail track maintenance to keep the serviceability of the railroad network. These maintenance projects (of different types) must be performed by suitable maintenance teams within a planning horizon. This article presents a time‐space network model to solve the track maintenance scheduling problem (TMSP). The objective is to minimize the total travel costs of the maintenance teams as well as the impact of maintenance projects on railroad operation, which are formulated by three types of side constraints: mutually exclusive, time window, and precedence constraints. An iterative heuristic solution approach is proposed to solve the large‐scale TMSP model with a large number of side constraints. The proposed model and solution approach are applied to a large‐scale real‐world problem. Compared to the current industry practice the model outcome eliminated all hard side‐constraint violations and reduced the total objective value (travel costs and soft side‐constraint violation penalties) by 66.8%.     

2D and 3D Optimal Parallel Image Warping

Spatial image warping is useful for image processing and graphics. In this paper, we present concurrent-read-exclusive-write (CREW) and exclusive-read-exclusive-write (EREW) parallel-random-access-machine (PRAM) algorithms that achieve O(1) asymptotic run time. The significant result is the creative processor assignment that results in an EREW PRAM algorithm. The forward algorithm calculates any nonscaling affine transform including arbitrary skewings, translations, and rotations. The EREW algorithm is the most efficient in practice, and the MasPar MP-1 with 16K processors rotates a 4-million-element image in under a second and a 2-million-element volume in one-half of a second. This high performance allows interactive viewing of volumes from arbitrary viewpoints and illustrates linear speedup. This practical efficiency is analyzed and illustrated by using a bridging model of computation. We develop the mixed cost communication machine (MCCM) to quantify the communication costs and correlate these costs to the MasPar MP-1. The forward algorithm has provable N = 1 congestion on the MCCM, while the backward algorithm has congestion N > 1 which varies with the transform. There are also important quality advantages using our direct warping techniques; empirical measurements are given to provide comparisons to multipass warps.     

Optimal Distributed Location Management in Mobile Networks

An important issue in the design of future Personal Communication Services (PCS) networks is the efficient management of location information. In this paper, we consider a distributed database architecture for location management in which update and query loads of the individual databases are balanced. We obtain lower bounds to the worst-case delay in locating a mobile user, to the average delay, and to the call blocking probability. We then propose a dynamic location management algorithm that meets these lower bounds. The optimality of this algorithm with respect to these three performance measures, as well as simplicity, make it an appealing candidate for distributed location management in PCS networks.     

Analysis of optical networks with heterogeneous grooming architectures

Traffic grooming in optical networks employing wavelength division multiplexing (WDM) has gained prominence due to the prevailing disparity between the user requirement and wavelength capacity. Nodes in an optical network get upgraded to the latest grooming technology slowly with time. Hence, WDM grooming networks are expected to employ heterogeneous grooming architectures. In this paper, we develop an analytical model to evaluate the blocking performance of WDM grooming networks with heterogeneous grooming capabilities. We demonstrate the accuracy of the analytical model by comparing the analytical results with that of the simulation. We observe that analytical models with and without precise knowledge of the grooming architectures predict similar performance. The proposed analytical model can be employed by resource placement algorithms that identify a set of nodes and links that need to be upgraded when the resources are limited.     

Computationally-efficient phased-mission reliability analysis forsystems with variable configurations

Several techniques and a software tool for reliability analyses that generally apply to fault-tolerant systems operating in phased-missions are given. Efficient models, using Markov chains without an explosion of the state space, are provided for missions consisting of multiple phases, during which the system configuration or success criteria can change. In different phases, the failure rates and the fault and error handling models can also change, and the duration of any phase can use deterministic or random models. An efficient reconfiguration procedure that is computationally more efficient than any existing technique is developed. The technique is demonstrated using a numerical example to show the effects of mission phases on the system reliability