Spatiotemporal Modelling of Water Balance Components in Response to Climate and Landuse Changes in a Heterogeneous Mountainous Catchment

Landuse change and climate change are the main drivers of hydrological processes. The purpose of this study was to analyse the separate and combined future effects of climate and landuse changes on water balance components on different spatial and temporal scales using the integrated hydrological Soil and Water Assessment Tool model. The study focused on the changes and relationship between water yield (WYLD) and sediment yield (SYLD) in the heterogeneous Taleghan Catchment in Iran. For future climate scenarios, RCP 4.5 and RCP 8.5 of GFDL-ESM2M GCM were used for 2020–2040. A Markov chain model was used to predict landuse change in the catchment. The results indicated an increase in precipitation and evapotranspiration. The findings also showed that the relationship between WYLD and SYLD is direct and synergic. Climate change has a stronger effect on WYLD than landuse change, whereas landuse change has a stronger effect on SYLD. The conversion of rangelands to barren land is the most critical landuse change that could increase SYLD. The highest increase in WYLD and SYLD in scenario RCP4.5 resulted from the combined effects of climate and landuse change. We estimated WYLD of about 295 mm and SYLD of around 17 t/ha. The proposed methodology is universal and can be applied to similar settings to identify the most vulnerable regions. This can help prioritize management strategies to improve water and soil management in watersheds.

     

The Electrolytic Ionic Strength Effect on Corrosion Resistance and Crystallinity of Plasma Electrolytic Oxidation (PEO) Coating Developed on Ti6Al4V

Protection of Metals and Physical Chemistry of Surfaces - The aim of this paper was to investigate the formation of an amorphous phase in the coating structure due to reduction in porosity and...     

Analysis of return-to-zero-on-off-keying over absolute polar duty cycle division multiplexing in dispersive transmission medium

We propose and investigate a technique to reduce the spectral width as well as increase the tolerance to chromatic dispersion (CD) using improved return-to-zero (RZ) on-off-keying (OOK) over absolute polar duty cycle division multiplexing (AP-DCDM) technique. The proposed channel multiplexing and demultiplexing are performed electrically using only one modulator for n number of users, which is very economical. It is demonstrated that the spectral width occupied by 30 Gb/s RZ-OOK without AP-DCDM measured at -20 dB from the peak power is around 105 GHz whereas, this value can be reduced to around 64 GHz for 30 Gb/s RZ-OOK over AP-DCDM. This amount of saving in the spectral width is a significant achievement, which leads to better tolerance to CD. Its tolerance to CD is in the range of plusmn109 and plusmn155 ps/nm, for the worst and the best users, respectively. These values are higher than that of 30 Gb/s conventional RZ-OOK, which is around plusmn86.5 ps/nm. At 120 Gb/s RZ-OOK over AP-DCDM (the worst user) has pre-amplified receiver sensitivity and optical signal to noise ratio (OSNR) of -22.5 dBm and 28.57 dB, respectively.     

Effect of Cl– and $${\text{NO}}_{3}^{ - }$$ Ions on Microstructure and Properties of TiO2–CeO2 Nanostructured Composite Coatings Obtained Through Plasma Electrolytic Oxidation (PEO) on Ti6Al4V

Protection of Metals and Physical Chemistry of Surfaces - Rare earth cerium oxide synthesized from cerium (III) chloride and cerium (III) nitrate salts in electrolytes were used to develop...     

Catalytic activity of multi-wall carbon nanotube supported manganese (III) porphyrin: an efficient,selective and reusable catalyst for oxidation of alkenes and alkanes with urea–hydrogen peroxide

Manganese complex of meso-tetrakis(4-hydroxyphenyl)porphyrin immobilised onto functionalised multi-wall carbon nanotubes (MWCNT) has been synthesised and characterised by elemental analysis, Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis) spectroscopy, powder X-ray diffraction and scanning electron microscopy. This catalyst, [Mn(THPP)OAc@MWCNT], was successfully applied for efficient epoxidation of alkenes and alkanes with urea–hydrogen peroxide. The role of the stoichiometric amounts of the acetic anhydride as an oxidant activator which introduce in situ peracetic acid has been discussed. This heterogeneous catalyst was highly reusable in the oxidation reactions and reused several times without significant loss of its catalytic activity.     

Realization of high capacity transmission in fiber optic communication systems using Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) technique

An electrical multiplexing technique, namely Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) is reported for high-speed optical fiber communication systems. It is demonstrated that 40 Gb/s (4 × 10 Gb/s) AP-DCDM system shows a clear advantage over conventional 40 Gb/s RZ-OOK with 50% duty cycle in terms of dispersion tolerance and spectral efficiency. At 40 Gb/s its tolerance to chromatic dispersion (CD) is 124 ps/nm and 194 ps/nm for the worst and the best user, respectively. These values are higher than that of 40 Gb/s RZ-OOK, which is around 100 ps/nm. The spectral efficiency, receiver sensitivity and OSNR for different number of channels are discussed. Comparison against other modulation formats namely duobinary, Non-Return-to-Zero (NRZ)-OOK and RZ-Differential Quadrature Phase-Shift Keying (RZ-DQPSK) at 40 Gb/s are made. It is shown that AP-DCDM has the best receiver sensitivity (−32 dBm) and better CD tolerance (±200 ps/nm) than NRZ-OOK and RZ-DQPSK. In reference to duobinary, AP-DCDM has better receiver sensitivity but worse dispersion tolerance.     

Developing monthly operating rules for a cascade system of reservoirs: Application of Bayesian Networks

In this paper, a Bayesian Network (BN) is utilized for developing monthly operating rules for a cascade system of reservoirs which is mainly aimed to control floods and supply irrigation needs. BN is trained and verified using the results of a reservoir operation optimization model, which optimizes monthly releases from cascade reservoirs. The inputs of the BN are monthly inflows, reservoir storages at the beginning of the month, and downstream water demands. The trained BN provides the probability distribution functions of reservoirs' releases for each set of input data. The long-term optimization model in monthly scale is formulated to minimize the expected flood and agricultural water deficit damages. The optimization model is developed using an extended version of the Varying chromosome Length Genetic Algorithm (VLGA-II). To incorporate reservoir preparedness for controlling the probable floods in each month, damages associated with floods with different return periods have been considered in the optimization model. For this purpose, a short-term optimization model which provides the optimal hourly releases during floods is utilized and linked to a flood damage estimation model. Damages due to deficit in supplying agricultural water demands are also calculated based on the functions of crop yield responses to deficit irrigation. The developed models are applied to the cascade system of the Dez and Bakhtiari Reservoirs in Southwest of Iran. The result of the trained BN is compared with the rules developed using classical and fuzzy linear regressions and it is shown that the total damage obtained by the BN-based operating rules is about 60 percent less than the total damage obtained using the fuzzy and classical regression analyses. The average relative error in estimating optimal releases is also reduced about 30 percent by using the BN-based rules.     

Effect of self-phase-modulation on dispersion compensated absolute polar duty cycle division multiplexing transmission

The effect of self-phase modulation (SPM) on 40 Gb/s absolute polar duty cycle division multiplexing (AP-DCDM) is investigated and reported. The study includes the influence of launched power, number of channels and dispersion compensation method. Dispersion post-compensation and combination of dispersion pre- and post-compensation are used to manage the transmission links. At high powers, SPM degrades the pulse recompression process and provides an upper bound on the AP-DCDM transmitted pulse energy. It is demonstrated that the 40 Gb/s AP-DCDM system shows a 4.1 dB improvement and less than 1 dB penalty in terms of SPM tolerance in comparison to 40 Gb/s 4-ary and on off-keying (OOK) systems, respectively. The SPM effect is stronger in the 100 post-compensated link than that in the combination of pre- and post-compensated links. Dispersion pre-compensation of 18 22 is found as the optimum range of pre-compensation ratio for AP-DCDM system, which makes optimisation of the launched power possible.