Survivability using traffic balancing and backup resource reservation in multi‐domain optical networks

Survivability in the geographically distributed backbone multi‐domain optical networks (MDONs) is critical because of issues related to its size, usage of resources, and domain management policies of the comprising domains. In MDONs, the emerging scheduled traffic is increasingly multivendor, multimedia, and periodic. It is high during the office (working) hours and low during the non‐office (non‐working) hours in a day. A connection failure during the office hours may result in huge amount of information being lost. Towards providing an acceptable level of service even when a connection fails, we first provide traffic balancing (TB) based solutions where the intra/inter‐domain traffic is slided (S1‐TB), shifted (S2‐TB), or slided as well as shifted (S3‐TB) based on the service level agreement between the client and domain service provider. Of the above solutions, the solution based on sliding as well as shifting (S3‐TB) performs best, and hence for further improvement in S3‐TB, we incorporate backup multiplexing with advance backup resource reservation (BRR) and evaluate the performance of the strategy and report results. The performance evaluation of the above strategies is compared with the existing extended path shared protection (EPSP) by a simulator developed in MATLAB and tested on three‐domain and five‐domain standard network topologies, on the metrics of blocking probability, network resource utilization ratio, network capacity utilized by backup route, wavelength link used per backup lightpath, and a newly introduced metric, network resource utilization index. As compared with the existing strategy EPSP, the S3‐TB and S3‐TB with BRR showed improved performance on all the metrics.     

Simulation of an experimental compartment fire by CFD

This paper analyses the experimental results, obtained in a compartment fire experiment [Kumar R. Studies on compartment fires. Ph.D. thesis. Indian Institute of Technology, Roorkee, 2004], by using CFD modelling. Experiments were conducted in a compartment by burning methanol as a fuel. Temperatures vs. time were recorded at 11 different locations in the compartment for three sizes of fires.     

Modeling Soil Water Uptake by Plants Using Nonlinear Dynamic Root Density Distribution Function

Water uptake by plants is one of the major components of water balance of the vadose zone that greatly influences the contaminant and moisture movement in variably saturated soils. In this study, a nonlinear macroscopic root water uptake model that includes the impact of soil moisture stress is developed. The model incorporates the spatial and temporal variation of root density in addition to the dynamic root depth considerations. The governing moisture flow equation coupled with the water extraction by plants term is solved numerically by an implicit finite-difference method. The simulation is performed for various physical scenarios subjected to different boundary conditions. The model is tested first without considering the water uptake and results are compared with observed data available in the literature for two cases. A nonlinear water uptake term is subsequently incorporated in the model which is then simulated for corn crop for constant root depth under various characteristic moisture availability environments. Results show that the water extraction rate is closely related to the soil moisture availability in addition to the root density. The plants are observed to extract moisture mainly from the upper root dense soil profile when water content is in an optimal range, otherwise, the peak of the uptake moves to other soil layers where the moisture is easily available. Finally, the model is applied to a corn field and simulated results are validated with field data. The simulated moisture content for 2 months of crop growing season shows a reasonably good agreement with the observed data.     

Analysis of groundwater quality using fuzzy synthetic evaluation

This paper reports the application of fuzzy set theory for decision-making in the assessment of physico-chemical quality of groundwater for drinking purposes. Methodology based on fuzzy set theory used to express the quality of water in the imprecise environment of monitored data and prescribed limits given in a non-probabilistic sense. Fuzzy synthetic evaluation model gives the certainty levels for the acceptability of the water based on the prescribed limit of various regulatory bodies quality class and perception of the experts from the field of drinking water quality. Application of fuzzy rule based optimization model is illustrated with 42 groundwater samples collected from the 15 villages of Ateli block of southern Haryana, India. These samples were analysed for 16 different physico-chemical water quality parameters. Ten parameters were used for the quality assessment using this approach. The analysis showed that four samples were in "desirable" category with certainty level of 35-58%, 23 samples were in "acceptable" category whose certainty level ranged from 37 to 75% and remaining 15 samples were in "not acceptable" category for drinking purposes with certainty levels from 44 to 100%. This concludes that about 64% water sources were either in "desirable" or "acceptable" category for drinking purposes.     

Polymerization of methyl methacrylate by charge-transfer mechanism with 2,2′-bipyridine and iron (III) complex

Polymerization of methyl methacrylate (MMA) by the charge-transfer complex formed by the interaction of 2,2′-bipyridine (bpy), MMA, and carbon tetrachloride (CCl₄) was studied in dimethylsulfoxide (DMSO) at 60°C. The rate of polymerization (R_p) is sensitive to the [CCl₄] at low concentration of CCl₄, but at a higher concentration it is practically independent of [CCl₄]. R_p is proportional to [MMA]^1.45±0.04 and [bpy]^0.52±0.04 when [CCl₄] > [bpy], and the average rate constant, k, at 60°C for the polymerization of MMA was 7.14 ± 0.40 × 10⁻⁶ L mol⁻¹s⁻¹. Kinetic studies showed that the polymerization proceeds through free radical intermediates. This article also reports the polymerization of MMA initiated by bpy and CCl₄ and accelerated by Lewis acid, hexakis (dimethylsulfoxide)iron(III) perchlorate [Fe(DMSO)₆](ClO₄)₃ at 60°C. The glass transition temperature and molecular weights of the samples were investigated by using differential scanning calorimetry and gel permeation chromatography techniques, respectively. Probable reaction mechanisms are proposed to explain the observed results. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2097–2103, 1997     

Advances in US Air Force hydraulic fluids

The US Air Force Wright Laboratory's Materials Directorate has been involved with the development and transition of advanced fluids and lubricants since the 1950s. The driving force for the development of new hydraulic fluids has primarily been and still is, improved fire resistance, although biodegradability and low toxicity have become increasingly important. This paper briefly traces the use of military aircraft hydraulic fluids from the beginning to the current state-of-the-art.     

Global estimates of evapotranspiration and gross primary production based on MODIS and global meteorology data

The simulation of gross primary production (GPP) at various spatial and temporal scales remains a major challenge for quantifying the global carbon cycle. We developed a light use efficiency model, called EC-LUE, driven by only four variables: normalized difference vegetation index (NDVI), photosynthetically active radiation (PAR), air temperature, and the Bowen ratio of sensible to latent heat flux. The EC-LUE model may have the most potential to adequately address the spatial and temporal dynamics of GPP because its parameters (i.e., the potential light use efficiency and optimal plant growth temperature) are invariant across the various land cover types. However, the application of the previous EC-LUE model was hampered by poor prediction of Bowen ratio at the large spatial scale. In this study, we substituted the Bowen ratio with the ratio of evapotranspiration (ET) to net radiation, and revised the RS-PM (Remote Sensing-Penman Monteith) model for quantifying ET. Fifty-four eddy covariance towers, including various ecosystem types, were selected to calibrate and validate the revised RS-PM and EC-LUE models. The revised RS-PM model explained 82% and 68% of the observed variations of ET for all the calibration and validation sites, respectively. Using estimated ET as input, the EC-LUE model performed well in calibration and validation sites, explaining 75% and 61% of the observed GPP variation for calibration and validation sites respectively.Global patterns of ET and GPP at a spatial resolution of 0.5° latitude by 0.6° longitude during the years 2000-2003 were determined using the global MERRA dataset (Modern Era Retrospective-Analysis for Research and Applications) and MODIS (Moderate Resolution Imaging Spectroradiometer). The global estimates of ET and GPP agreed well with the other global models from the literature, with the highest ET and GPP over tropical forests and the lowest values in dry and high latitude areas. However, comparisons with observed GPP at eddy flux towers showed significant underestimation of ET and GPP due to lower net radiation of MERRA dataset. Applying a procedure to correct the systematic errors of global meteorological data would improve global estimates of GPP and ET. The revised RS-PM and EC-LUE models will provide the alternative approaches making it possible to map ET and GPP over large areas because (1) the model parameters are invariant across various land cover types and (2) all driving forces of the models may be derived from remote sensing data or existing climate observation networks.     

Perspective study of abrasive water jet machining of composites — a review

Journal of Mechanical Science and Technology - Even though composite materials are prominent amongst the advanced engineering materials, but machining of composites using conventional machining...     

MgNb2O6:Dy3+ nanophosphor: A facile preparation,down conversion photoluminescence and UV driven photocatalytic properties

Series of (1–9 mol %) dysprosium (Dy³⁺) ions doped MgNb₂O₆ (MNO) nanophosphors were synthesized by chemical combustion process and their photo luminescent and photocatalytic behaviours were examined. Powder X-ray diffraction (PXRD) reveals the columbite structure and crystal structure parameters were calculated. The average crystallite size was found to be in the range of 20–30 nm as calculated by Scherrer's method. The photoluminescence (PL) of MgNb₂O₆:Dy³⁺ (λ_exc-393 nm) reflects white emission for the prepared samples as confirmed by CIE and CCT. The photocatalytic activities of these nanophosphors were probed for the decolorization of acid red 88 (AR-88) under UV light irradiation. The photocatalyst with MgNb₂O₆:Dy³⁺ (5 mol %) showed enhanced activity of 97%, attributed to effective separation of charge carriers. All the above experimental results confirm that, the optimized phosphor is quite useful for WLEDs, solid-state lighting applications and as a photocatalyst.