Multi-dimensional analysis of soil moisture dynamics in trickle irrigated fields. II: Model testing

The mathematical model which was developed in part I of this work for multi-dimensional analysis of soil moisture in irrigated fields is converted into computer algorithms. The algorithms are capable of emulating many field conditions of practical applications during both design and operation phases. The model is subjected to various tests, the results of which are reported here. The tests in various modes of simulations verified the numerical performance of the model and the accuracy of its predictions. The model provides a powerful tool for detailed studies of soil moisture dynamics in one or multi-dimensional problems irrigated fields     

Phase relations in the ternary system Cu-In-Se

The phase relations of the ternary system Cu-In-Se were studied at 750° C by quenching experiments. Special attention was given to the region CuInSe₂In₂Se₃-In₄Se₃. Only four ternary phases with extended homogeneity ranges were found to exist. They were characterized by X-ray powder diffraction, electron microprobe analysis (EK8PA)' end optical microscopy. Differential thermal analysis (DTA) investigations allowed us to construct theT-x diagram of the Cu₂Se-In₂Se₃. out between 47 and 100 mol% In₂Se₃. Besides, it was also possible to give a tentative diagram of the solid-liquid equilibria at 750° C and to get some information on the sub-solid existence fields beside the Cu₂Se-In₂Se₃ cut.     

Vitamin allowance of cosmonauts during preflight training and after completing short space flights

Supply of the main and doubling crews of cosmonauts with vitamins C, A, D, E, B1, B2, B6, PP, and B12, folic acid and carotinoids was studied during training and after the completion of short-term space flights (from 4 to 13 days). As the result of the investigation conducted during the intensive training, 1 month before the space flight some cases of certain vitamins deficiency were revealed. Administration of additional vitamins during 2 weeks before the flight led to a rise in the cosmonauts' supply with vitamins. The findings obtained after the short-term space flights evidence an intensive metabolization of vitamins and increased vitamin requirements during this period.     

Dimension-structure dependences for the strength of two-phase polycrystalline inorganic materials

Examples are considered of experimental dependences of the strength of two-phase inorganic materials on the shape and size of structural elements, and also dimensional parameters: the mean value of the free path and the mean distance between particles. The structural condition for achieving the maximum strength values for two-phase metallic, cermet, and ceramic materials with a high second phase content is established and substantiated by experiment. An approximate analysis of the dislocation structure of interphase boundaries is performed and their contribution to strengthening of two-phase materials with a dispersed and microlayered structure is demonstrated.Translated from Problemy Prochnosti, No. 1, pp. 3–14, January, 1991.     

Nitrogen transformations and fate of other parameters in columnar denitrification

Soil columns were used as denitrifying reactors in the laboratory where the feed solutions were composed of nitrified solution and kitchen waste. Five different carbon (expressed as methanol) to nitrogen ratios ranging from 2:1 to 6:1 were applied to twenty soil columns. Transformation of nitrogen compounds and fate of associated parameters during denitrification were investigated. A high degree of denitrification was obtained for C:N ratios of 4:1 or higher. Rate of application was not a significant factor in this study. Most of the TKN present in the feed solutions escaped the denitrification reactors. Production of total alkalinity during denitrification was found to be somewhat lower than the values reported in the literature. In some cases the column effluents contained higher solids concentrations than in the influent.     

Stability of imperfect conical shells with helical reinforcement

The article explains a method of numerical calculation of the stability of imperfect conical shells with helical reinforcement under uniform external pressure. It also investigates the effect of the amplitude of local initial imperfections on the critical loads.Translated from Problemy Prochnosti, No. 12, pp. 67–69, December, 1991.     

Effects of flux enhancing polymer on the characteristics of sludge in membrane bioreactor process.

A newly developed membrane performance enhancer (MPE) was used to prevent membrane fouling in a membrane bioreactor (MBR) process. It transpired that 1,000 mg/l of MPE reduced polysaccharide levels from 41 mg/I to 21 mg/I on average under the experimental condition. Repeated experiments also confirmed that 50-1,000 mg/l of MPE could reduce membrane fouling significantly and increase the intervals between membrane cleanings. Depending on MPE dosages and experimental conditions, trans-membrane pressure (TMP) increase was suppressed for 20-30 days, while baseline TMP surged within a few days. In addition, MPE allowed MBR operation even at 50,000 mg/l of total solid and reduced permeate COD. However, no evidence of toxicity for sludge was found from respiratory works.