Assessing the effect of nutrient mitigation measures in the watersheds of the Southern Bight of the North Sea

The Seine, Somme, and Scheldt Rivers (France, Belgium, and Netherlands) are the major delivering rivers flowing into the continental coastal zone of the Southern Bight of the North Sea, an area regularly affected by eutrophication problems. In the present work, the Seneque-Riverstrahler model was implemented in a multi-regional case study in order to test several planned mitigation measures aimed at limiting stream nutrient contamination and restoring balanced nutrient ratios at the coastal zone.This modeling approach, which is spatially distributed at the basin scale, allows assessing the impact of any change in human activities, which widely differ over the three basins. Here, we define realistic scenarios based on currently proposed measures to reduce point and non-point sources, such as the upgrading of wastewater treatment, the introduction of catch crops, and the development of extensive farming. An analysis of the current situation showed that a 47-72% reduction in P point-source emissions within the three basins could be reached if the intended P treatment was generalized to the largest treatment plants. However, only an overall 14-23% reduction in N could be achieved at the outlet of the three basins, by combining improved wastewater treatment and land use with management measures aimed at regulating agricultural practices. Nonetheless, in spite of these efforts, N will still be exported in large excess with respect to the equilibrium defined by the Redfield ratios, even in the most optimistic hypothesis describing the long-term response of groundwater nitrate concentrations.A comprehensive assessment of these mitigation measures supports the need for additional reductions of nutrient losses from agriculture to control harmful algae development. It also stresses the relevance of this mechanistic approach, in which nutrient transfers from land to sea can be calculated, as an integrated strategy to test policy recommendations.     

An effective method for solving nonlinear fractional differential equations

A new technique based on beta functions is applied to compute the exact formula for the Riemann–Liouville fractional integral of the fractional-order generalized Chelyshkov wavelets. An approximation method based on the wavelets is proposed to effectively solve nonlinear fractional differential equations. Illustrative examples show that the proposed method gives solutions with less errors in comparison with the previous methods.

     

Regularity of the Inertial Manifolds for Evolution Equations in Admissible Spaces and Finite-Dimensional Feedback Controllers

Journal of Dynamical and Control Systems - Our main aims in this paper are to investigate the regularity of inertial manifolds for non-autonomous semi-linear evolution equations and to give an...     

High-pressure cylindrical acoustic resonance diffusion measurements of methane in liquid hydrocarbons

A novel cylindrical acoustic resonance method for the measurement of gas diffusion into liquids at high pressures is described. The measurements were per formed in a vertically oriented cylindrical acoustic resonator containing both the liquid solvent and gaseous diffusant while under high-precision isothermal and isobaric control. Individual resonance modes of the liquid column, the gas column, and the two-phase coupled fluid are resolved in the fast Fourier trans form acoustic-resonance spectrum (FFT-ARS). High-resolution acoustic spectra measured at frequent time intervals reveal the changes which accompany the diffusion fusion of gas into the liquid phase. One change, namely, the growth in length of the liquid column, results in a systematic shift to higher frequencies of axial modes in the gas column. The temporal behavior of this moving boundary, together with quantitative measurement of the flow to the gas column required to sustain the constant pressure, permits determination of the gas-into-liquid diffusion coefficient. Diffusion coefficients were determined from the change in frequency as a function of time of axial resonance modes in the gas-phase virtual cylinder as the surface of the underlying liquid phase advanced due to gas absorption. Measurements of the systems methane/n-octane, methane/n-nonane, and methane/n-decane were performed as a function of temperature at a pressure of 250 psia. Comparisons is made to results obtained elsewhere and by other methods but at the same temperatures and pressure.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Taylor wavelet method for fractional delay differential equations

We present a new numerical method for solving fractional delay differential equations. The method is based on Taylor wavelets. We establish an exact formula to determine the Riemann–Liouville fractional integral of the Taylor wavelets. The exact formula is then applied to reduce the problem of solving a fractional delay differential equation to the problem of solving a system of algebraic equations. Several numerical examples are presented to show the applicability and the effectiveness of this method.

     

Cost assessment and ecological effectiveness of nutrient reduction options for mitigating Phaeocystis colony blooms in the Southern North Sea: an integrated modeling approach

Nutrient reduction measures have been already taken by wealthier countries to decrease nutrient loads to coastal waters, in most cases however, prior to having properly assessed their ecological effectiveness and their economic costs. In this paper we describe an original integrated impact assessment methodology to estimate the direct cost and the ecological performance of realistic nutrient reduction options to be applied in the Southern North Sea watershed to decrease eutrophication, visible as Phaeocystis blooms and foam deposits on the beaches. The mathematical tool couples the idealized biogeochemical GIS-based model of the river system (SENEQUE-RIVERSTRAHLER) implemented in the Eastern Channel/Southern North Sea watershed to the biogeochemical MIRO model describing Phaeocystis blooms in the marine domain. Model simulations explore how nutrient reduction options regarding diffuse and/or point sources in the watershed would affect the Phaeocystis colony spreading in the coastal area. The reference and prospective simulations are performed for the year 2000 characterized by mean meteorological conditions, and nutrient reduction scenarios include and compare upgrading of wastewater treatment plants and changes in agricultural practices including an idealized shift towards organic farming. A direct cost assessment is performed for each realistic nutrient reduction scenario. Further the reduction obtained for Phaeocystis blooms is assessed by comparison with ecological indicators (bloom magnitude and duration) and the cost for reducing foam events on the beaches is estimated. Uncertainty brought by the added effect of meteorological conditions (rainfall) on coastal eutrophication is discussed. It is concluded that the reduction obtained by implementing realistic environmental measures on the short-term is costly and insufficient to restore well-balanced nutrient conditions in the coastal area while the replacement of conventional agriculture by organic farming might be an option to consider in the nearby future.     

Novel Active Contour Model for Image Segmentation Based on Local Fuzzy Gaussian Distribution Fitting

A novel active contour model is proposed, which incorporates local information distributions in a fuzzy energy function to effectively deal with the intensity inhomogeneity. Moreover, the proposed model is convex with respect to the variable which is used for extracting the contour. This makes the model independent on the initial condition and suitable for an automatic segmentation. Furthermore, the energy function is minimized in a computationally efficient way by calculating the fuzzy energy alterations directly. Experiments are carried out to prove the performance of the proposed model over some existing methods. The obtained results confirm the efficiency of the method.     

Improved electrochemical performance and durability of butane-operating low-temperature solid oxide fuel cell through palladium infiltration

Low-operating-temperature solid oxide fuel cells (LT-SOFCs) with various kinds of fuel, such as hydrocarbons, biogas, natural gas, and oxygenated fuel has been an active SOFC research topic. However, conventional SOFC anodes comprised of nickel metal and yttria-stabilized zirconia composite (Ni-YSZ) experience rapid degradation when operated for the butane direct internal steam reforming (B-DISR), especially at a low temperature (LT) range. This study reveals that the impregnated Pd into the Ni-YSZ anode support of thin-film SOFCs (TF-SOFCs) is effective for achieving better performance and stability regarding the TF-SOFC in B-DISR at 600°C. Adding Pd as a dopant into Ni-YSZ significantly promotes the catalytic activity due to the Pd-Ni alloy formation, both on the YSZ grain and the Ni grain surface. The electrochemical performance of cells without Pd (Ni-YSZ cell) and a Pd-infiltrated Ni-YSZ anode (Pd-Ni-YSZ cell) are compared at 600°C for the B-DISR mode at a ratio of steam-to-carbon of 3. Finally, long-term durability tests were performed at 600°C and under 0.15 A cm⁻². The Pd infiltration decreases the deterioration rate to 0.63 mV h⁻¹ after the first 80 hours of operation for the Pd-Ni-YSZ cell, which was a significant improvement from that of the Ni-YSZ cell, 3.75 mV h⁻¹ after 40 hours of operation.