Kinetics of microbial nitrification: nitrite-nitrogen oxidation

The kinetics of nitrite-nitrogen oxidation by enriched Nitrobacter cultures were examined under various temperatures (9°–35°C), pH (6.0–8.5), and microbial concentrations. For the substrate concentrations examined (100–1100 mg N1⁻¹) the reaction was zero order and correlations between temperature, pH, microbial concentrations and reaction rates were formulated. Inhibition by free ammonia and nitrous acid is discussed. This study of enriched cultures of nitrobacter organisms also provide some insight into the growth characteristics of this fastideous organism under conditions of dense population and severe environmental conditions (temperature and pH).     

Impact of the River Maine Drainage Scheme on Hydro-Power Generation

A comparison is made between pre- and post-drainage scheme river flows recorded on the River Maine, Co. Antrim. A method of using five-year reference periods has been applied to the mean daily flows to smooth and eliminate, as far as possible, variations due to climatic changes.
Any loss of energy production which might have been due to changes in river flow was examined for turbine installations at a factory at Cullybackey. The quantities of usable water, and hence potential energy production, were calculated for each of the post-scheme five-year periods and compared with a pre-scheme five-year reference period. Any potential loss was then represented by a depreciation factor. It was found that no measurable loss of potential energy production has occurred on the River Maine in the post-scheme period.     

Arsenic and heavy metals in soils associated with regional geochemical anomalies in South-West England

Regional geochemical maps have shown extensive anomalies of arsenic, copper and other heavy metals in those parts of South-West England associated with mineralised zones around the granite intrusion. Studies in the vicinity of the River Tamar and of the metamorphic aureole around Dartmoor have confirmed significantly higher concentrations of arsenic and heavy metals in soils contaminated by mining, smelting and mineralisation compared with those from nearby control areas. Arsenic and copper show the greatest degree of enhancement ranging up to 900 ppm As and 2000 ppm Cu in both alluvial and upland topsoils within the Tamar area. Preliminary analyses indicate that the trace metal content of pasture herbage-reflects in part the degree of soil contamination. Maximum concentrations of 35 ppm As and 22 ppm Cu in autumn sampled herbage were found at contaminated sites compared with mean values of less than 0.5 ppm As and 8 ppm Cu in control areas. Geochemical reconnaissance surveys based on stream sediment sampling provide a useful indication of areas wherein widescale soil contamination may occur.     

Solar heating and night radiation cooling by a Roof Radiation Trap

The paper describes a new system, the Roof Radiation Trap, which utilizes solar energy for heating of buildings in winter and nocturnal radiation for cooling in summer. The radiation trap consists of fixed insulating layer separated from the flat roof and glazing, protected by hinged insulating panel, in the southern gap between the roof and the fixed insulation. This fixed insulating layer is covered by corrugated metal sheets, painted white, which serve as nocturnal radiators in summer.The radiation trap is integrated with the building, thermally as well as architecturally. In winter the sun energy penetrates through the glazing and is absorbed directly in the roof, which serves as a combined collector, storage for one night and heat distribution system.The hot air in the space between the flat roof and the fixed insulation is blown into a thermal storage of gravel, under the floor or inside the building. The stored heat is “recovered” by forced convection during cloudy days.In summer the penetration of solar radiation during daytime is prevented by the hinged insulating panel. At night the painted external metal layer is cooled by outgoing radiation and the air under the corrugations is blown into the space of the radiation trap and cools the roof, which, in turn, serves as a heat sink during the next day. Nocturnal evaporative cooling can supplement the radiant cooling.     

Electromagnetic Effect of an Alternating Current Traction Power Supply System with a High-Voltage Power Cord on Electrical Installations and Networks of Nontraction Consumers

Russian Electrical Engineering - In this paper, we ground a method for calculating switching overvoltages including the discharge of lightning currents into the contact network and into a...     

Diagnostics of Multioperation Processes Using Basic Cells of Digital Homogeneous Structures

Russian Electrical Engineering - The cells of homogeneous digital structures designed for multioperation process diagnostics are considered in the form of graphic models. Digital circuits and...     

Time-dependent reliability of ageing structures: an approximate approach

Concrete structures may deteriorate over time due to aggressive service environments, leading to a reduction in their strengths, stiffnesses and reliabilities. In general, the assessment of time-dependent reliability of ageing structures must consider uncertainties in structural deterioration as well as non-stationarities in the structural load processes. This paper develops an approximate method for assessing the impact of structural deterioration and non-stationary live loads on structures, which requires only low-dimensional integration and reduces the cost of assessing time-dependent reliability over a service life extending to 50 years significantly. This approximate method is demonstrated through several examples. The importance of non-stationarities in the resistance and load processes on time-dependent reliability is illustrated and the accuracy of the method is confirmed in several cases utilising Monte Carlo simulation.