Technologies have driven big data collection across many fields, such as genomics and business intelligence. This results in a significant increase in variables and data points (observations) collected and stored. Although this presents opportunities to better model the relationship between predictors and the response variables, this also causes serious problems during data analysis, one of which is the multicollinearity problem. The two main approaches used to mitigate multicollinearity are variable selection methods and modified estimator methods. However, variable selection methods may negate efforts to collect more data as new data may eventually be dropped from modeling, while recent studies suggest that optimization approaches via machine learning handle data with multicollinearity better than statistical estimators. Therefore, this study details the chronological developments to mitigate the effects of multicollinearity and up-to-date recommendations to better mitigate multicollinearity.
The past few years have witnessed increased in the potential use of wireless sensor network (WSN) such as disaster management, combat field reconnaissance, border protection and security surveillance. Sensors in these applications are expected to be remotely deployed in large numbers and to operate autonomously in unattended environments. Since a WSN is composed of nodes with nonreplenishable energy resource, elongating the network lifetime is the main concern. To support scalability, nodes are often grouped into disjoint clusters. Each cluster would have a leader, often referred as cluster head (CH). A CH is responsible for not only the general request but also assisting the general nodes to route the sensed data to the target nodes. The power-consumption of a CH is higher then of a general (non-CH) node. Therefore, the CH selection will affect the lifetime of a WSN. However, the application scenario contexts of WSNs that determine the definitions of lifetime will impact to achieve the objective of elongating lifetime. In this study, we classify the lifetime into different types and give the corresponding CH selection method to achieve the life-time extension objective. Simulation results demonstrate our study can enlarge the life-time for different requests of the sensor networks.
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