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Earthmoving equipment is a large generator of emissions. Accordingly, it is important to understand the underlying parameters affecting performance, in order to operate the equipment in the most emissions-efficient way. The paper aims to provide an original examination of the truck-oriented earthmoving parameters of haul grade, payload and truck type and their little known influence on fuel use and emissions. Observed field data ‒ on fuel use, payloads and cycle times from four different earthmoving operations ‒ are compared with theoretical estimates. The assumptions behind the DRET (Department of Resources, Energy and Tourism ‒ Australia) energy model for truck fuel use and hence emissions estimation, are examined and improvements suggested. Conclusions are given on haul grade, payload and truck type usage that lead to least emissions. Suggestions for overcoming some limitations of the DRET model are given, and a modified DRET model is introduced.

Purpose – The dispatching of trucks in earthmoving and like operations is worthy of examination because of potential emission reductions and savings through the appropriate allocation of trucks to excavators and dump sites. The paper aims to discuss this issue. Design/methodology/approach – Truck dispatching is performed through linear programming (LP) and the effect of truck allocation on unit emissions and unit costs established. Number of trucks, unit cost and unit emissions are all considered as objective functions. A cut and fill operation on a road project provides a numerical case study. Findings – It is demonstrated analytically that the minimum unit emissions solution is the same as that for minimum unit cost. Numerical results from the case study, including sensitivity analyses on the underlying parameters, support this conclusion. Practical implications – The LP dispatching solution, based on minimizing truck numbers and unit costs, accordingly impacts the environment the least in terms of emissions. The paper's results will be of interest to those designing and managing earthmoving and like operations for production, cost and emissions. Originality/value – While LP has been used by others to examine optimum unit cost dispatching, this paper is original in examining the dispatching or truck allocation based on both unit cost and unit emissions, and showing the relationship between the optima for both.

Traditionally, surface mining has been organised based on a minimum unit cost criterion. However, there is an increasing awareness for the need to reduce carbon emissions due to their negative environmental impacts. This paper explores the relationship between the optimal unit cost surface mining operation and the optimal unit emissions operation. It examines the influence of a range of operation parameters including truck size, payload, fuel use and travel and load times. It is demonstrated theoretically that the optima with respect to unit cost and unit emissions coincide, and this coincidence is invariant on changing operation parameters. To support the theoretical result, data from an extensive field study are used, including time and production measurements, and collected fuel burn data and its conversion to emissions. The paper’s findings will be of interest to those involved in designing and managing surface mining, and similar operations such as quarrying and earthmoving.

An analysis of the statistical distribution of the ultimate tensile strength (UTS) of cast Al2O3 containing aluminium matrix composite and its matrix alloy (A357) was carried out using different volume fractions of alumina particles (0, 5, 10 15 and 20%). The scatter of UTS data was assessed by the use of two parameter Weibull analysis. Results for the matrix alloy and metal matrix composites in the heat treated condition (T6) were compared. It was found that the addition of reinforcing particles to the matrix alloy resulted in lower UTS and ductility and increased scatter of results. Weibull modulus of cast MMC rods was found to be about 22 in the matrix alloy, falling to six in the 20% alumina MMC. Fractographic examinations of lower strength specimens showed that oxide films and the consequent porosity play an important role in fracture. The future potential, if MMCs can be manufactured without entrained oxides, is seen to be exciting.

The flow behaviour of aluminium alloy matrix composites containing Al2O3 and SiC particles is studied. A357 aluminium alloy was the matrix alloy common to both metal matrix composites (MMCs). Reinforcing particles were similar in shape and size (40 μm). Both MMCs were made by the stir casting process using parameters optimised so far as possible. The flowability of the MMCs was studied by measuring the fluidity of strips cast in a permanent mould. The results showed that the fluidity of both MMCs appeared to be reduced by increasing percentage addition of particles and further reduced by increasing times and temperature. It is proposed that much of this behaviour is not the result of the added reinforcing particles but the result of oxide films necessarily entrained by the stir casting process. The agglomeration of additions commonly seen in particulate MMCs is also attributed to the entrainment of clusters of additions as they enter the liquid through the surface oxide film.

The paper explores minimum emission configurations in earthmoving and like operations, including quarrying and open-cut mining. Emissions data, based on field observations and available in the public literature, are used to derive operation configurations that lead to minimum emissions. Such configurations are compared with conventional minimum cost solutions in order to give guidance as to the best way to configure and manage earthmoving operations. Variables considered in the analyses performed include truck fleet size, truck capacity and loading, loader capacity and haul route parameters. It can be shown for certain assumptions and configurations that the minimum emissions per production solution coincides with the minimum cost per production solution. In such circumstances, managing earthmoving, quarrying and open-cut mining operations in conventional costefficient ways leads to least emissions; it also follows that not managing such operations in a cost-efficient way will lead to unnecessary emissions. The paper's derivations are original and will be of interest to those designing and managing earthmoving, quarrying and open-cut mining operations, particularly with reference to sustainability.

Brief introduction to the problem. The paper examines the influence of varying operation parameters such as equipment heterogeneity, payload, and travel times, on unit emissions and unit costs in earthmoving and like operations. The need to minimise cost and maximise production of earthmoving and like operations has led to such operations being heavily scrutinised. With environmental issues becoming more important, there is now a need to additionally scrutinise and minimise emissions. Cycle times and production were measured in a cut-and-fill case study operation; average fuel burn data are converted to idling and nonidling emission fractions; and queuing theory is used for the theoretical evaluation of production for varying operation parameters. It is demonstrated that the optimum fleet sizes in terms of minimum unit costs and minimum unit emissions coincide in earthmoving operations. The result is independent of any specific operational parameters. The paper concludes that the traditional way of undertaking earthmoving operations, namely configuring to give minimum unit costs, will also result in minimum unit emissions. And that configuring differently to that will lead to unnecessary emissions. The result carries over to quarrying and surface mining operations.

In this paper, the axiomatic design is introduced for controlling a power electronic converter. The main idea of axiomatic design is to introduce variables affecting the desired performances of the system most independently possible. The control process is presented for a Buck converter to achieve constant efficiency and output voltage ripple.

In this paper, the axiomatic design is introduced for designing the power electronic converters. The main idea of axiomatic design is to introduce variables affecting the desired performances of the system most independently possible. The design process is presented for a Buck converter.