Statistical approach to determination of overhaul and maintenance cost of loading equipment in surface mining

The purpose of this research was to develop a new approach in determination of overhaul and maintenance cost of loading equipment in surface mining. Two statistical models including univariate exponential regression (UER) and multivariate linear regression (MLR) were used in this study. Loading equipment parameters such as bucket capacity, machine weight, engine power, boom length, digging depth, and dumping height were considered as variables. The results obtained by models and mean absolute error rate indicate that these models can be applied as the useful tool in determination of overhaul and maintenance cost of loading equipment. The results of this study can be used by the decision-makers for the specific surface mining operations.

Simulation of Nigerian Crude Oil Types for Modular Refinery (Topping Plant) Operations

This research study focused on the need to curb scarcity and importation of petroleum finished products in oil-producing nation Nigeria through the operation of conventional modular refineries in conjunction with major refineries operating efficiently. Hence, the study focused on the suitability and operations of conventional modular refinery processes by considering twenty different types of Nigerian crude oil for crude oil assay analysis and classification using Aspen Hysys. The crude oil assay results categorized the twenty Nigerian crude oil types as light and medium sweet crude, while based on recovery volume percent at a true boiling point of 370℃, the twenty crude oil types were categorized into Group A (crude oil with recovery volume above 80%), Group B (crude oil with recovery volume between 70% and 79%) and Group C (crude oil with recovery volume below 70%) respectively. Besides, light and medium sweet oil types were simulated in a conventional modular refinery (topping plant) at different numbers of column trays (25, 29, 35, 40 and 48) to determine their product yield. Based on product yield and equipment costs at different numbers of tray columns, a modular refinery with twenty-nine column trays was applied in this study. Thus, twenty Nigerian crude oil types were simulated in a conventional modular refinery of 30,000 barrel per day capacity and twenty-nine column trays respectively to evaluate their product yield and tray compositions.

Multi-period Two-stage Robust Optimization of Radial Distribution System with Cables Considering Time-of-use Price

In the existing multi-period robust optimization methods for the optimal power flow in radial distribution systems,the capability of distributed generators(DGs)to regulate the reactive power,the operation costs of the regulation equipment,and the current of the shunt capacitor of the cables are not considered.In this paper,a multi-period two-stage robust scheduling strategy that aims to minimize the total cost of the power supply is developed.This strategy considers the time-ofuse price,the capability of the DGs to regulate the active and reactive power,the action costs of the regulation equipment,and the current of the shunt capacitors of the cables in a radial distribution system.Furthermore,the numbers of variables and constraints in the first-stage model remain constant during the iteration to enhance the computation efficiency.To solve the second-stage model,only the model of each period needs to be solved.Then,their objective values are accumulated,revealing that the computation rate using the proposed method is much higher than that of existing methods.The effectiveness of the proposed method is validated by actual 4-bus,IEEE 33-bus,and PG 69-bus distribution systems.