Concept drift due to hidden changes in context complicates learning in many domains including nancial prediction, medical diagnosis, and communication network performance. Existing machine learning approaches to this problem use an incremental learning, on-line paradigm. Batch, oo-line learners tend to be ineeective in domains with hidden changes in context as they assume that the training set ...

background: this research studied the feasibility of a simple method for extracting gold from central processing units (cpus) of computer circuit boards without solvent. methods: ceramic and composite cpus of computer circuit boards were used. gold was extracted using a hydrometallurgical method in six stages: grinding of cpus, leaching in nitric acid, leaching in aqua regia, removing the exces...