Oxides in general, by reason of their chemical inertia in oxidising atmospheres, high melting point and high mechanical strength, afford a suitable protective coating at high…
Abstract
Oxides in general, by reason of their chemical inertia in oxidising atmospheres, high melting point and high mechanical strength, afford a suitable protective coating at high temperatures. Aluminium oxide in particular also has good thermal shock resistance, good impact resistance at high temperatures, and moderate self‐sealing properties. Hitherto it has been applied to turbojets, space components and rocket jets by flame spraying or arc plasma spraying. Since the characteristic properties of the coating, and hence its efficiency, are directly associated with its degree of structural perfection, the application technique has great importance; in this sense it may be thought, that chemical vapour deposition, allowing the ‘construction’ of the coating atom by atom or molecule by molecule, could produce a material having chemical and physical properties close to the theoretical. For this and other reasons the authors have already had the idea of studying the possible application of this technique for the preparation of a coating of aluminium oxide.
The Suez Irrigation Canal is the source of drinking water to a large community. Complaints have been raised regarding the odor and unpleasant taste of drinking water. The problems…
Abstract
Purpose
The Suez Irrigation Canal is the source of drinking water to a large community. Complaints have been raised regarding the odor and unpleasant taste of drinking water. The problems encountered reveled enrichment of the Canal with nutrients, degraded water quality and nuisance caused by algal growth. This paper aims to investigate these claims by evaluating the interaction between water and sediment with ecological indicators.
Design/methodology/approach
Bioassessments were used as a primary tool to evaluate the biological conditions and identify the degree of water quality degradation in the Suez Irrigation Canal. The monitoring program integrates biological, chemical, and physical data assessment. Several field surveys were carried out to these areas during the period between March 2003 and February 2005 (over 23 months) for acquiring all possible information about the current situation and to explore the impact of human activities along the canal banks on the canal ecosystem. Seasonal variations of phytoplankton and zooplankton standing crop, species diversity as well as physico‐chemical characteristics of water, sediment, fish and aquatic weeds at the intakes of drinking plants and from the discharge of agricultural and domestic drains into the Canal were investigated.
Findings
Preliminary field investigations showed great amounts of discharged wastes at several locations to the canal water creating unique conditions, which vary with changes of volume and properties of the discharged wastes. Rotifer and green algae for example demonstrated seasonal variable response to the ecological variations. Myriophyllum spicatum, Potamageton nodsus and Polygonum Salicfolium were the most common types of recorded weed. The Myriophyllum spicatum is the dominant submerged plant. The canal was characterized by high concentrations of HCO3‐ as well as high pH >8.2 which provides a favorable habitat for the growth of Myriophyllum spicatum. The results illustrated the ability of using the aquatic weed as biomarkers for monitoring heavy metals contaminates in the canal. The evidence suggests that there is a degree of selectivity in metals uptake and partitioning within the plant compartments.
Originality/value
The current paper adopts the idea of utilizing multiple organism groups in the bioassessment to effectively detect ecological change when they occur in one of the most important waterways in Egypt. These different organism groups are suited for detection various stressors, providing warnings and detection of stress impacts at different scales. The study presented provides decision makers with important information that can assist them in making objective decisions related to the design of monitoring programs based on scientific research.
Details
Keywords
W.G. Heath and B.O. Heath
BEFORE a detailed consideration of internal stresses may be made, it is necessary to define external loadings which are possibly critical. This involves the consideration of…
Abstract
BEFORE a detailed consideration of internal stresses may be made, it is necessary to define external loadings which are possibly critical. This involves the consideration of manoeuvres throughout the altitude range of the aeroplane, to a severity fixed by aerodynamic or specification values of speed and normal acceleration.
This paper analyses a number of techniques that can be used to compare complex data sets, such as those arising from electromagnetic simulation and experimentation. The techniques…
Abstract
This paper analyses a number of techniques that can be used to compare complex data sets, such as those arising from electromagnetic simulation and experimentation. The techniques assessed are: correlation, several reliability factors and feature selective validation. The study examines the performance of each technique for data comparison. The paper provides a comprehensive summary of the techniques and compares their performance and comments on their use in the validation of numerical modelling codes and model designs.