Hal Gurgenci

Crack detection in hollow section structures through coupled response measurements

Detection of a circumferential crack in a hollow section beam is investigated using coupled response measurements. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. This matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. The suitability of the mode coupling methodology is first demonstrated analytically. Laboratory test results are then presented for circular hollow section beams with artificially generated cracks of varying severity. It is shown that this method has the potential as a damage detection tool for mechanical structures.

Longwall Shearer Cutting Force Estimation

Longwall mining is an underground coal mining method that is widely used. A shearer traverses the coal panel to cut coal that falls to a conveyor. Operation of the longwall can benefit from knowledge of the cutting forces at the coal/shearer interface, particularly in detecting pick failures and to determine when the shearer may be cutting outside of the coal seam. It is not possible to reliably measure the cutting forces directly. This paper develops a method to estimate the cutting forces from indirect measurements that are practical to make. The structure of the estimator is an extended Kalman filter with augmented states whose associated dynamics encode the character of the cutting forces. The methodology is demonstrated using a simulation of a longwall shearer and the results suggest this is a viable approach for estimating the cutting forces. The contributions of the paper are a formulation of the problem that includes: the development of a dynamic model of the longwall shearer that is suitable for forcing input estimation, the identification of practicable measurements that could be made for implementation and, by numerical simulation, verification of the efficacy of the approach. Inter alia, the paper illustrates the importance of considering the internal model principle of control theory when designing an augmented-state Kalman filter for input estimation.

Fault detection and identification for longwall machinery using SCADA Data

Despite the most refined maintenance strategies, equipment failures do occur. The degree to which an industrial process or system is affected by these depends on the severity of the faults/failures, the time required to identify the faults and the time required to rectify the faults. Real-time fault detection and identification (FDI) offers maintenance personnel the ability to minimise, and potentially eliminate one or more of these factors, thereby facilitating greater equipment utilisation and increased system availability.

Mobile plant maintenance and the dutymeter concept

Provides examples of duty variability based on field tests conducted during ordinary operating conditions. A severity‐based maintenance approach is introduced as complementary to the reliability‐centred maintenance initiatives currently being introduced in various mining companies. The essential component of this approach is a series of equipment monitors (called “dutymeters”) that continuously monitor and log the real duty on the machine as well as some machine parameters that can be used for machine health diagnostics. Describes application of this concept to a range of machinery including draglines, shovels, haul trucks and longwall equipment.

Parametric equations using generic representation of joint stiffness

For most design and recertification work on tubular structures, it is not practical to determine the joint hot spot stresses experimentally or using detailed finite element analysis. Therefore, parametric equations were developed in the past for various joint geometries to relate stress concentration factors around the joints to basic joint geometrical parameters. Such parametric equations have limited applications to reinforced joints because the nature of reinforcement varies and may be difficult to represent by a generic set of geometric parameters. In this paper, a new method is introduced to include local joint stiffness in the parametric equations represented by a generic characteristic of the joint determined by modal analysis. The parametric equations produced in this paper can be applied to any reinforced T-joint regardless of the nature of reinforcement. This is especially useful in those cases where the exact nature of reinforcement is not known, for example, hidden in the interior or deteriorated through age or fabrication error The dimensionless joint stiffness parameter can be calculated by a simple modal test and a beam model without needing to know the nature and details of the reinforcement.

In situ damage detection in frame structures through coupled response measurements

Due to the existence of global modes and local modes of the neighbouring members, damage detection on a structure is more challenging than damage on isolated beams. Detection of an artificial circumferential crack on a joint in a frame-like welded structure is studied in this paper using coupled response measurements. Similarity to real engineering structures is maintained in the fabrication of the test frame. Both the chords and the branch members have hollow sections and the branch members have smaller sizes. The crack is created by a hacksaw on a joint where a branch meets the chord. The methodology is first demonstrated on a single hollow section beam. The test results are then presented for the damaged and undamaged frame. The existence of the damage is clearly observable from the experimental results. It is suggested that this approach offers the potential to detect damage in welded structures such as cranes, mining equipment, steel-frame bridges, naval and offshore structures.

Techno-economic analysis of supercritical carbon dioxide power blocks

Developing highly efficient power blocks holds the key to enhancing the cost competitiveness of Concentration Solar Thermal (CST) technologies. Supercritical CO2 (sCO2) Brayton cycles have proved promising in providing equivalent or higher cycle efficiency than supercritical or superheated steam cycles at temperatures and scales relevant for Australian CST applications. In this study, a techno-economic methodology is developed using a stochastic approach to determine the ranges for the cost and performance of different components of central receiver power plants utilizing sCO2 power blocks that are necessary to meet the Australian Solar Thermal Initiative (ASTRI) final LCOE target of 12 c/kWh.Developing highly efficient power blocks holds the key to enhancing the cost competitiveness of Concentration Solar Thermal (CST) technologies. Supercritical CO2 (sCO2) Brayton cycles have proved promising in providing equivalent or higher cycle efficiency than supercritical or superheated steam cycles at temperatures and scales relevant for Australian CST applications. In this study, a techno-economic methodology is developed using a stochastic approach to determine the ranges for the cost and performance of different components of central receiver power plants utilizing sCO2 power blocks that are necessary to meet the Australian Solar Thermal Initiative (ASTRI) final LCOE target of 12 c/kWh.

Investigating the use of methane as diesel fuel in off-road haul road truck operations

A scope study is conducted to investigate the technical and commercial feasibility of converting existing mine haul truck engines to a fuel regime of methane and diesel. A dual fuel engine with two technology options of homogeneous gas charge and high pressure direct injection are considered. The results of this study show that cost reduction is only possible when methane is available at a cost saving that compensates for the expense of building a new fuel infrastructure, and a clean combustion is expected. In contrast to diesel-only engines, particulate emissions in dual fuel engines are less. However, unburned methane in the exhaust gases or significant methane leakage must be seriously taken into consideration for replacing diesel with methane. This scope study argues that the dual fuel operation with HGC/CNG technology is expected to be feasible even at a relatively small truck fleet size.

Water Consumption Comparison Between a Natural Draft Wet Cooling Tower and a Natural Draft Hybrid Cooling Tower—An Annual Simulation for Luoyang Conditions

ABSTRACT The Merkel method, the Poppe approach, and an empirical equation are employed in the developed computer program to predict the evaporation loss for the natural draft wet cooling tower (NDWCT). All the three models are validated with the experimental results. The calculation results in the NDWCT of a 300-MW power plant in Luoyang show that both the Merkel method and the empirical equation could not make the accurate evaporation loss prediction as the Poppe approach does. The annual water consumption and economic benefits for the power plant employed with the NDWCT and the natural draft hybrid cooling tower (NDHCT) are calculated by using the hourly weather condition. The results show that the power plant would save more than 95% of water but lose US

Selected Papers From the 17th IAHR (International Association for Hydro-Environment Engineering and Research) International Conference on Cooling Tower and Heat Exchanger

15,464,306 per year by replacing the NDWCT with the NDHCT.