A Novel Fault Detection and Localization Scheme for Mesh All-optical Networks Based on Monitoring-cycles

We previously showed the feasibility of a fault detection scheme for all-optical networks (AONs) based on their decomposition into monitoring-cycles (m-cycles). In this paper, an m-cycle construction for fault detection is formulated as a cycle cover problem with certain constraints. A heuristic spanning-tree based cycle construction algorithm is proposed and applied to four typical networks: NSFNET, ARPA2, SmallNet, and Bellcore. Three metrics: grade of fault localization, wavelength overhead, and the number of cycles in a cover are introduced to evaluate the performance of the algorithm. The results show that it achieves nearly optimal performance.     

The variant cycle-cover problem in fault detection and localization for mesh all-optical networks

With the soaring channel speed and density in all-optical networks (AONs), the risk of high data loss upon network faults increases quickly. To manage network faults efficiently, an m-cycle based fault detection and localization (MFDL) scheme has been introduced recently. This paper verifies the necessary and sufficient condition for achieving the complete fault localization (CFL) in MFDL, which is defined as the case that every single network fault can be located to a unique link. We model the m-cycle construction as a new mathematical problem: the variant version of the constrained cycle-cover problem (vCCCP) and explore its formal expression. The model includes the consideration of the cycle-length limit, cycle number, and wavelength cost, while also keeps the CFL achievable. A two-phase branch-and-bound (B&B) algorithm was developed for solving the vCCCP, which guarantees to find near-optimal solutions. This algorithm is then applied to four typical and four random network examples to validate and assess the performance. The results are analyzed and compared with some previously reported algorithms, in terms of fault localization degree, cycle number, wavelength overhead, and cost reduction. The performance evaluation and comparison reveal that the new model and algorithm could significantly reduce the MFDL cost, including both the cost of monitoring devices and reserved wavelengths.     

Solution properties of poly(fluorostyrene-co-chlorostyrene) copolymers. I. Light scattering,differential refractometry and viscometry

The weight-average molecular weights (M?_w) of nominally random, unfractionated copolymers of ortho- and para-fluorostyrene and ortho- and para-chlorostyrene were determined by light scattering measurements in tetrahydro-furan, toluene, carbon tetrachloride and chloroform. It was shown that there is no significant variation in measured M?_w in the various solvents, a finding indicating that the copolymers are not compositionally heterogeneous. Intrinsic viscosity measurements in the same solvents established a consistent relationship between [n] and M?_w despite the differences in copolymer compositions. It was not possible to establish a similar relationship between the second virial coefficient A₂ and M?_w. It was concluded that measurements of the specific refractive index increment could be used for determining copolymer composition if the measurements were performed in thermodynamically poorer solvents. The results established for the Mark-Houwink constant α, intrinsic viscosity, and A₂ values indicated that these solvated copolymer molecules are in a less expanded conformation than are polystyrene molecules of similar molecular weights in a given solvent.     

Pressure drop and flowrate characteristics of a liquid phase spout-fluid bed at the minimum spout-fluid flowrate

Data on the minimum spout-fluid flowrates and the pressure drop in the annulus at that flowrate are presented as a function of bed height and nozzle diameter for a bed spout-fluidized with water. The column was 62.6 mm. in diameter and contained 3.09 mm. glass particles. The particle Reynolds number at the minimum fluidizing velocity was 91.6. A plot of the annular vs. the nozzle flowrate shows that the minimum spout-fluid flowrates fall on a straight line between the minimum fluidizing and minimum spouting flowrates. The annular pressure drop is explained using an extension of the theory of Mamuro and Hattori.     

Fast and accurate analysis of 3-D curved optical waveguide couplers

The structure-related (SR) finite-difference beam-propagation method is applied to integrated optical couplers employing curved waveguide sections. A general nonorthogonal coordinate system is introduced that matches the local structure geometry, yielding a more accurate analysis with coarser meshes than standard schemes, thus providing significant computational resource savings. Furthermore, the algorithm is easily interfaced with conventional schemes. Examples of curved two-dimensional and three-dimensional directional waveguide couplers are examined to show the advantages and generality of SR schemes as well as to explore the role of the extra degrees of freedom offered by nonorthogonal meshing.     

Indicators and a Neuro-Fuzzy Based Model for the Evaluation of Water Supply Sustainability

In the field of water management, the evaluation of sustainability has no universal methodological approach nor any consensus regarding the definitions of sustainability or sustainable development. There is an essential need therefore for a precise definition of sustainability in different water management fields. This paper deals with the sustainability of one part of urban water management, namely a water supply. A precise definition of a sustainable water supply system is given, together with a methodological framework that quantifies the degree of water supply sustainability. The proposed framework relies on the proposed quasi-strong sustainability concept, its components (dimensions), their particular relationships and corresponding indicators representing individual processes in the water supply system and utility. The processing of indicators is performed through a joint fuzzy logic/neural network (ANFIS) model. In order to evaluate each sustainability component, separate ANFIS models were created whose results were aggregated into a single result (sustainability index). According to the presented framework, sustainability is evaluated for 17 public water supply systems/utilities in Croatia.     

Low-loss reconfigurable OADM for metro core optical network

Reconfigurable optical add/drop multiplexers (ROADMs) will play a key role in next-generation dynamically provisioned wavelength networks. Existing ROADM subsystems, manufactured with different designs and technologies, are suffering from either high insertion losses, especially for the passing-through (express)-channels, or high manufacturing costs that are preventing their rapid deployment in networks. An architecture for an ROADM subsystem that integrates the best features of the latest available ROADM designs is proposed. The proposed ROADM subsystem, denoted as a Hybrid-ROADM, exhibits a lower insertion loss (~7 dB for express-channels) than existing ROADMs while offering simplification and cost benefit. A metro network testbed has been configured to demonstrate and compare the performance of the proposed Hybrid-ROADM module against currently available ROADM subsystems. The obtained results indicate that our Hybrid-ROADM shows better performance in metro networks than the latest available ROADM subsystems and will reduce the overall network operating costs.     

Kinetics of in situ epoxidation of soybean oil in bulk catalyzed by ion exchange resin

The kinetics of the epoxidation of soybean oil in bulk by peracetic acid formed in situ, in the presence of an ion exchange resin as the catalyst, was studied. The proposed kinetic model takes into consideration two side reactions of the epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups as well as the reactions of the formation of the peracid and epoxy groups. The catalytic reaction of the peracetic acid formation was characterized by adsorption of only acetic acid and peracetic acid on the active catalyst sites, and irreversible surface reaction was the overall rate-determining step. Kinetic parameters were estimated by fitting experimental data using the Marquardt method. Good agreement between the calculated and experimental data indicated that the proposed kinetic model was correct. The effect of different reaction variables on epoxidation was also discussed. The conditions for obtaining optimal epoxide yield (91% conversion, 5.99% epoxide content in product) were found to be: 0.5 mole of glacial acetic acid and 1.1 mole of hydrogen peroxide (30% aqueous solution) per mole of ethylenic unsaturation, in the presence of 5 wt% of the ion exchange resin at 75°C, over the reaction period of 8 h.     

Decomposition of a class of linear electrical networks for calculation of total power

A new method of decomposition of linear electrical networks for calculating total power is presented. By an iterative procedure, on the basis of decomposition of the electrical network, the branches containing power sources (voltage and/or current) are selected first until the remaining network becomes passive. Then, one calculates the power dissipated by the decomposed networks supplied by the corresponding power sources. Total power dissipated by impedances of the starting networks is equal to the sum of powers dissipated by impedances of the decomposed networks, under the condition that all impedances Z of the network are either resistive \({\text{Im}}(Z)=0\) or reactive \({\text{Re}}(Z)=0\) or mutually equal.