International Journal of Engineering Research in Africa Vol. 13

Abstract: Metrologists at the National Institute for Standards-NIS (Egypt) develop length measuring devices to provide reliable and less expensive metrological systems for accurate measurement. Length Laboratory Group investigates the sources of errors in the absolute measurement of length using the improved Abbe vertical metroscope. The investigation includes analyzing of errors induced by optical alignment, environment, and instrument. Errors due to environment and vibration are reduced by controlling the area in which the technique is placed. The instability in the readings caused by temperature fluctuations is handled by averaging 1000 points/sec. To ensure ideal contact between the probe of the comparator and the surface of the artifact, holographic technique is used in testing the uniformity of the probe at the area of contact. Other factors influencing the measurements such as material expansion of the artifact and optical source used in the measurement are considered in the uncertainty evaluation. The uncertainty in the absolute measurement of gauge block length of 80mm is found to be ±0.2µm. The results of measuring some pieces using the absolute method are in good agreement with the corresponding reference values given in their calibration certificate.

Abstract: Algeria has a fragile ecosystem, characterized by a relative scarcity of water resources and their preservation is a vital imperative. The excessive intake in the natural environment of nitrogen and phosphate load in wastewater, from agricultural activities, domestic and industrial pollution, represents a pollution threat and a serious danger to the aquatic environment. Municipal wastewater contains various wastes, and usually consists of about 99.94% liquid and 0.06% solids. If this wastewater is not treated or improperly collected, it can affect both public health and environment. In our study, we will focus on the biological treatment by natural lagoon and activated sludge, which suits perfectly our country, where space and climate are favorable factors; our main objective is to eliminate the maximum existing phosphorus in wastewater by these biological treatments, which can actually eliminate total phosphorus. Through these modes of treatment we try to remove the maximum of organic matter and phosphorus in the wastewater. Consequently, the receiving environment is preserved.