Comparison of SPOT cloud cover quality index against meteorological surface observations

A quality index, based on cloud contamination within the image, is assigned to each SPOT scene. In this study, the information content, of such a quality index, in terms of cloud cover, was tested by comparing it with coincident meteorological surface observation. Global observations during the period June-October 1995 were analysed, starting with the investigation of the spatial and temporal variability of cloud covers from both kinds of observations. Comparisons for a series of 'dependent' datasets generated by varying the time (from 0.5 to 1.5 h) and space (from 5 to 100 km) matching criteria were performed successively. Results were reported as 5 x 9 cloud-class contingency tables and relevant statistics evaluating the correlation between the two observations. The analyses showed an overall good agreement between the two cloud-cover estimations, the correlation was slightly lower (10%) than that obtained by comparing SYNOP against SYNOP. Compared with SYNOP observations, SPOT tended to slightly underestimate cases of broken cloud-cover. One of the most important sources of disagreement was the lack of quantitative information in the three-class cloud quality index code found in 30% of the SPOT images used in this study. When processed as described here, the information contained in the SPOT cloud cover quality index is consistent with the surface observation of cloud cover.     

Selective renovation of eutrophic wastes—phosphate removal

This is the first part of a basic investigation concerning the multicomponent chloride/sulfate/phosphate/nitrate equilibrium on anion resins. The study is to throw more light on the fundamentals of poly-anions, heterovalent equilibria on anion resins, and to develop a selective process to remove eutrophic species from sewage effluents. In this paper the chloride/phosphate equilibrium is described for a large selection of different anion resins and the selectivity dependence on several external (i.e. solution pH, concentration and composition) or internal (i.e. resin basicity, porosity, matrix etc.) parameters evaluated.     

Optimal running and planning of a biomass-based energy production process

We propose mathematical programming models for solving problems arising from planning and running an energy production process based on burning biomasses. The models take into account different aspects of the problem: determination of the biomasses to produce and/or buy, transportation decisions to convey the materials to the respective plants, and plant site locations. Whereas the “running model” is linear, we propose two “planning models”, both of which are mixed-integer nonlinear programming problems. We show that a spatial branch-and-bound type algorithm applied to them is guaranteed to converge to an exact optimum in a finite number of steps.     

24 hour monitoring of blood pressure in premature and full-term new born babies

Using a 24 hour monitoring of the systo-diastolic blood pressure, 127 new born babies were studied in the first five days of life. 45 of these new born babies were premature (35 +/- 1 week) and 82 full-term. The results showed an overlap in the systo-diastolic blood pressure in the 2 groups of subjects with a rise and fall in pressure in the 24 hour period and no fall in pressure during the night typical to a healthy adult.     

Ion selective electrodes for measurements in fresh waters

Ion selective electrodes (ISE), useful for measurement in fresh waters, are reviewed with special emphasis to the kind of ISE commercially available and to the interference problems of each type. The most common procedures, direct method and known addition method are outlined with relative advantages in different cases. Applications of the ISE in field measurements have been realized in a Somalia survey with simple equipment and results are reported.     

Chloride/sulphate exchange on anion resins. kinetic investigation,viii. influence of some physico-chemical properties of the resins

Experimental exchange rates for Cl^-/SO⁼₄ exchange on strictly comparable anion resins in 0.006N solution confirm the unfavorable correlation between kinetics and selectivity.Furthermore, evaluation of the influence of other physico-chemical properties of the resins (i.e., nature of matrix, type of amine, etc) seems to support the hypothesis that chemical interactions, and not only diffusional effects, in the resin phase play a leading role on rate control.     

Chloride/sulfate exchange on anion resins. Kinetic investigations. Chemical control in selective exchanges

Rate determinations for the Cl^-/SO⁼₄ exchange on anion resins in very diluted systems (1 ÷ 6 × 10^-3N), where resin selectivities for the divalent ion are drastically raised by the electroselectivity effect, show convincing evidence that the chemical reaction rate on fixed charges controls the overall process kinetics. Activation energies, in particular, (up to 16.83 kcal/eq) are definitely out of the range for usual diffusion-controlled kinetics.A spherically-symmetrical diffusion model with a billiard-ball-like mechanism of site-to-site jumping of ions inside the resin is suggested.     

Phosphates and ammonia recovery from secondary effluents by selective ion exchange with production of a slow-release fertilizer

A process for the reduction of eutrophic potential in urban secondary effluents. which comprises the selective exchange of phosphates on a weak anion resin and of ammonia on clinoptilolite, is described. Sodium chloride is used to regenerate both resins, with some Ca(OH)₂ added for clinoptilolite. By adding Mg(OH)₂, eventually precipitated with lime from sea water, the premium quality, slow-release fertilizer MgNH₄PO₄-6H₂O is recovered from the concentrated regeneration streams, which can then be recycled. Laboratory evaluations of the hydrolysis extent of the weak anion resin in the presence of bicarbonates showed that a steady-state is attained with resin exchange capacity reproducibly averaging about 80 mmol phosphates 1,⁻. The preliminary runs on a pilot plant for the tertiary treatment of urban sewage are also presented.