Application of baby deck initiation to reduce coal damage during cast blasting

ABSTRACT

The extra explosive energy used in cast blasting reduces the amount of overburden to be handled by the machinery but increases the risk of damage to the underlying coal. This damage will lead to reduced coal recovery and may negate much of the benefit sought from cast blasting. The Julius Kruttschnitt Mineral Research Centre in close association with the Australian open cut coal mining industry has conducted a blast monitoring program to understand and quantify the role of cast blasting in coal damage and loss. This paper attempts to explain the mechanisms of coal damage and the influence of toe confinement on coal damage during cast blasting.     

Optimal maintenance, repairmen, and control strategies for systems with breakdowns

Optimal preventive maintenance and repairmen policies for a system of machines subject to degradation with age and intermittent breakdowns and repairs are derived using optimal control theory. When this system of machines forms part of a dynamic process control system, a method of obtaining optimal closed-loop control law is indicated.     

State space formulation of ammonia reactor dynamics

The specific objective of this paper is to develop a state space model of a tubular ammonia reactor which is the heart of an ammonia plant in a fertiliser complex. A ninth order model with three control inputs and two disturbance inputs is generated from the nonlinear distributed model using linearization and lumping approximations. The lumped model is chosen such that the steady state temperature at the exit of the catalyst bed computed from the simplified state space model is close enough to the one computed from the nonlinear steady state model. The model developed in this paper is very useful for the design of continuous/discrete versions of single variable/multivariable control algorithms.     

Databases with uncertainty and lineage

This paper introduces uldbs, an extension of relational databases with simple yet expressive constructs for representing and manipulating both lineage and uncertainty. Uncertain data and data lineage are two important areas of data management that have been considered extensively in isolation, however many applications require the features in tandem. Fundamentally, lineage enables simple and consistent representation of uncertain data, it correlates uncertainty in query results with uncertainty in the input data, and query processing with lineage and uncertainty together presents computational benefits over treating them separately. We show that the uldb representation is complete, and that it permits straightforward implementation of many relational operations. We define two notions of uldb minimality—data-minimal and lineage-minimal—and study minimization of uldb representations under both notions. With lineage, derived relations are no longer self-contained: their uncertainty depends on uncertainty in the base data. We provide an algorithm for the new operation of extracting a database subset in the presence of interconnected uncertainty. We also show how uldbs enable a new approach to query processing in probabilistic databases. Finally, we describe the current state of the Trio system, our implementation of uldbs under development at Stanford. This work was supported by the National Science Foundation under grants IIS-0324431, IIS-1098447, and IIS-9985114, by DARPA Contract #03-000225, and by a grant from the Boeing Corporation.