Routing is an important challenge in WSN due to the presence of hundreds or thousands of sensor nodes. Low Energy Adaptive Clustering Hierarchy (Leach) is a hierarchical routing and data dissemination protocol. Leach divides a network domain into several sub-domains that are called clusters. Non-uniformity of cluster distribution and cluster heads (CHs) selection without considering the positions of other sensors may reduce the quality of cluster selection. Sensor nodes send data packets over long distances. Imperialist Competitive Algorithm (ICA) is an optimization algorithm inspired by social phenomenon. It considers colonization process as a stage of socio-political evolution. We improve performance of the Leach algorithm using imperialist approach and study its efficacy in terms of energy consumption, coverage and cluster uniformity and compare with those of the Leach algorithm. Selection of suitable value for radio communication radius over the network lifetime is a trade-off between connectivity and sensors energy consumption. Empowering Leach with ICA helps to find the best location of a CH in every cluster, conserve energy significantly, increase network lifetime, and maintain network connectivity. It can significantly reduce the number of active sensors going out of range over the lifetime of a network.

Energy is one of the important factors in wireless sensor networks. For further usage and to increase the network lifetime, researchers are always looking for ways which tend to reduce energy consumption. Clustering of sensor nodes is one of the best ways that can significantly increase the network lifetime. In this paper, using nodes weighting based on the density and node’s energy that be used in W-Leach algorithm, a new method is provided. In our method, the effects of weighting in the higher rounds have been decreased so that the nodes with inadequate density but higher energy in the higher rounds do get a fair chance to become a cluster-head. MATLAB simulation shows that the proposed method increases the network lifetime compared to W-Leach and others protocols.

Solidified samples of fuel oil combustion bottom ash with two sets of Ordinary Portland Cement (OPC) and Pozzolan added OPC were investigated with three sets of chemical Leaching tests. Toxicity characteristic Leaching test (TCLP) results classified waste material and its solidification products as hazardous. Although Ni and Cr have over-Leached, but their close examination with Sequential Chemical Extraction (SCE) test revealed new insights as follows. Nickel fixation in cement matrix has shifted over 20% of Leachable Ni from first 4 fractions of SCE test to residual fraction with less likelihood of Leaching. Chromium fixation in matrix has made shifts on Leachable fractions that are not generally in favor of a successful fixation in matrix. In the case of Cd Leaching, the only obvious finding from SCE test is that solidification processes have made a slight shift between fractions in bound to Iron and Manganese oxide and fraction in bound to carbonates. Compared to TCLP results for different mixtures, it can be concluded that Cd fixation has been done properly and significant change in Leaching probability was not caused by solidification processes. Results of “Alkalinity, Solubility and Release as a function of pH” test indicate over regulation in the case of Pb and Cr Leaching in different pHs. Results indicate need for more delicate interpretation of TCLP test results when several management scenarios are available and practical.