Effect of alkaline earth metal or iron contaminants on properties of viscose

Conclusions The effect of salts of alkaline earth metals and iron on the physico-chemical indices of viscose — viscosity, ripeness, and filterability — has been investigated.In amounts which exceed the content allowed by the All-Union State Standard in viscose by a factor of 3–4, calcium and magnesium ions do not cause a significant impairment in the physico-chemical indices of the viscose.Even at a content of 28 mg/liter, the presence of trivalent iron salts in a viscose causes a sharp impairment in its filterability, especially on prolonged ripening.Strict control of the trivalent iron content of viscose during the process of preparing it for spinning is necessary.Siberian Technological Institute. Translated from Kimicheskie Volokna, No. 2, pp. 17–18, March–April, 1987.     

Economic aspects of membrane processes

Care must be exercised, in predicting operating costs for membrane desalination systems for electricity, labor, chemicals, etc. The assumptions made in establishing unit costs can greatly affect the predicted operating cost and hence the ultimate investment decision. The use of data estimating the quantities of chemicals, power, etc., expected to be used per unit of production can assist in predicting costs, as then site-specific cost data can be used. The fact that 0.2 pounds of acid per kgal of permeate is required in a Florida RO plant is more useful for predicting operating costs of an RO plant on the Island of Anegata than is the fact that acid costs at the Florida plant are $0.03/kgal of water produced. Data based on units rather than costs are presented for seven RO facilities and one ED facility in this paper for use in this type of analysis.     

A model of density of states in amorphous Si, C and SiC from time-of-flight measurement

The temperature dependence of the electron drift mobility in glow-discharged undoped hydrogenated amorphous silicon, carbon and silicon carbide films with stoichiometric compositional (a-Si_0.5C_0.5:H) has been measured by the time-of-flight method. All films displayed the same behaviour of the transient current and dispersion parameters, which can be explained by assuming a gaussian distribution of tail states near the conduction band. The results obtained results corroborated the common nature and degree of disorder of the conduction band tail in all four-coordinated amorphous semiconductors.     

Investigation of the heat treatment processes of resin-bonded refractories in an atmosphere consisting of the products of sublimation and decomposition of the binder

Conclusions Heat treatment of the resin-bonded refractories in an atmosphere consisting of the products of sublimation and decomposition of the binder leads to a significant improvement in the properties of the specimens (in particular, in the coked condition). The increase in the content of the residual carbon, the mechanical strength of the specimens, and their hydration resistance are determined by the heat treatment temperature. The highest levels of the physical and the technological properties are obtained after heat treating the specimens in the 400–600°C range. In this case, the most significant effect is observed in the lime-periclase refractories and the minimum effect is obtained in the resin-periclase refractories.The increased hydration resistance of the resin-bonded refractories containing free calcium oxide (the lime-periclase and the periclase-lime refractories) owes mainly to fixing up of CaO during the heat treatment process and to the formation of the protective calcium carbonate films at the surface of the fired dolomite grains.Translated from Ogneupory, No. 2, pp. 10–13, February, 1992.     

Corundum hydraulically hardening rammed compounds with a reduced grain size

Conclusions The production and use of rammed hydraulically hardening corundum compounds with different maximum grain sizes (from 1 to 7 mm) permits intermediate repairs of the linings of ladles of a steel ladle treatment unit, increasing their life.It is possible to determine the quantity of binder for obtaining the maximum strength by calculation by use of the coefficient of optimization, which is the portion of binder required per unit of specific surface of the mixture of filler grains. For the corundum hydraulically hardening compounds the optimum value of this coefficient is 0.8–1.2.Translated from Ogneupory, No. 2, pp. 40–43, February, 1987.     

Automated procedure to determine the thermodynamic stability of a material and the range of chemical potentials necessary for its formation relative to competing phases and compounds

We present a simple and fast algorithm to test the thermodynamic stability and determine the necessary chemical environment for the production of a multiternary material, relative to competing phases and compounds formed from the constituent elements. If the material is found to be stable, the region of stability, in terms of the constituent elemental chemical potentials, is determined from the intersection points of hypersurfaces in an (n−1)$(n-1)$-dimensional chemical potential space, where n$n$ is the number of atomic species in the material. The input required is the free energy of formation of the material itself, and that of all competing phases. Output consists of the result of the test of stability, the intersection points in the chemical potential space and the competing phase to which they relate, and, for two- and three-dimensional spaces, a file which may be used for visualization of the stability region. We specify the use of the program by applying it both to a ternary system and to a quaternary system. The algorithm automates essential analysis of the thermodynamic stability of a material. This analysis consists of a process which is lengthy for ternary materials, and becomes much more complicated when studying materials of four or more constituent elements, which have become of increased interest in recent years for technological applications such as energy harvesting and optoelectronics. The algorithm will therefore be of great benefit to the theoretical and computational study of such materials.     

Utility of stereoscopic displays for indirect-vision driving and robot teleoperation

The effectiveness of an active shutter-glasses stereoscopic display (SD) and a passive polarised SD was evaluated in a live robot-teleoperation task and a simulated indirect-vision driving task in various terrains. Overall, participants completed their tasks significantly faster with the SDs in three-dimensional (3D) mode than with the SDs in the baseline 2D mode. They also navigated more accurately with the SDs in 3D mode. When the effectiveness of the two types of SDs was examined separately, results showed that the active shutter-glasses SD resulted in faster responses and task completion times than the passive polarised SD, though most of the differences failed to reach statistical significance. Perceived workload when interacting with the two SD systems did not differ significantly between the active versus passive display types or between the 3D and 2D modes of operation; however, participants reported more severe discomfort after interacting with the passive polarised SD.     

Palm kernel shell as a lightweight aggregate for concrete

These concrete mixes of widely differing water/cement ratios were made using palm kernel shell as course aggregate. The properties tested include the physical properties of the shell, the compressive, flexural and tensile splitting strengths of the concrete. These properties were compared with those of similar concrete specimens made with crushed granite as course aggregate. Results of the tests suggest that palm kernel shell cannot produce concrete with compressive strength above 30 MPa. However, for concrete grade 25 and below, the material was found to compare favourably with other conventional aggregate such as crushed granite.     

Periclase-Carbon Components for Use in the Refractory Lining of the Steel-Tapping Channel of a 370-Ton Converter

Tests of periclase-carbon blocks for the converter's steel-tapping channel available from the Kombinat Magnezit JSC were carried out in an oxygen-converter shop at the Magnitogorskii Metal-and-Steel Works JSC. The new refractory materials are shown to have a higher endurance as compared to the conventional periclase blocks, which made it possible to increase the operational efficiency of converters.