Spoil pile stability in an open pit coal mine is a common problem and the Red Hills Lignite Mine in Choctaw County is no exception. The mine has had spoil stability problems of their spoil dragline bench since the beginning of their activity in 2002. They have managed to stabilize the conditions by installing prefabricated vertical drains (PVD) to consolidate the layers below the spoil dragline bench, which tended to fail due to an increase in pore water pressure. In this study, the capability of analyzing and predicting future pore water pressure conditions is examined. With the use of the stability model Slope/w and local stress calculations, the predictability of the necessity of PVDs and their spatial distribution are analyzed. The outcomes prove to be circumstantial to local pore water pressure and geology changes, therefore, the spacing between drains could be adapted to the local conditions potentially saving costs.

This thesis presents advanced algorithms for realtime detection of dragline duty, the quantification of its causes and the combined optimisation of dragline motion to minimise cycle time and duty. Draglines are large, powerful, rotating, multibody systems that operate in a similar manner to cranes and certain pick and place robots. Duty is an estimate of fatigue damage on the dragline boom caused by cyclic stresses that are associated with the repetitive dig and dump operation. Neither realtime detection of duty nor the quantification of its causes were previously available. In addition, no previous researchers have optimised the dynamic motion of mining equipment to achieve the combined maximisation of productivity and minimisation of maintenance measures. The advanced duty detection system was developed to improve feedback to dragline operators. The algorithms that were developed are based on the mechanics of dragline motion and fatigue. In particular, fatigue cycles in measured stress are identified at the earliest possible time, based on a novel proof and modification to the rainflow cycle counting algorithm. The contributions of specific causes to each individual stress range are quantified based on the mechanics of operator dependent control and dragline dynamics. In this manner, specific causes of duty are measured. The algorithms confirmed the significant contribution from operator dependent factors and identified the major causes, attributing 28% of the total duty to out-of-plane bucket motion and 15% to dynamic vibration. Further improvements to dragline performance required the development of a dragline dynamic model for offline testing and optimisation. A complete, condensed set of equations for a four-degree-of-freedom nonlinear coupled model of a dragline was derived using Lagrange’s method, allowing direct insight into dragline behaviour not available from previous research. The model was used to investigate the relationship between motor power, operator behaviour, bucket trajectory, productivity and duty during the swing and return phases of operation. Significant potential for increasing productivity and reducing duty was demonstrated. The advanced duty detection system and the dragline model were validated with field measured data, video footage, alternative modelling and expert review. Realtime and end-of-cycle feedback was simulated over many cycles of measured data. Experts from industry and research were consulted to verify the causes of duty based on detailed measured data analysis. The forces, stresses and out-of-plane angle predicted by the dragline model were closely compared with measured data over various indicative cycles. The dragline model was also validated against an alternative model constructed in ADAMS. The development of the dragline model enabled model-based numerical optimisation. Significant nonlinearities in the model and the constraints necessitated the use of the Lagrange multiplier method. The bucket trajectory during the swing and return phase was directly optimised. In order to minimise cycle time and duty, a penalty for duty incurred was added to the cycle time, effectively maximising long-term productivity. For a slew torque optimisation scenario using measured rope lengths, the numerical optimisation performance was shown to be 10-30% better than manual optimisation and 50-60% better than the operator performance. This thesis outlines several significant contributions to improving dragline performance. Underpinning the advanced duty detection system are three significant contributions to fatigue cycle counting algorithms: a proof of the equivalence of two pre-existing algorithms; a new algorithm that enables realtime detection of duty; and an algorithm that can attribute duty to specific causes. These novel feedback tools can provide realtime operator feedback and identify the causes of excess duty and when it was incurred. A complete and condensed set of equations for the four-degree-of-freedom model enabled, for the first time, the optimisation of dragline operation to concurrently reduce duty and increase productivity. The models and feedback algorithms were validated with field measured data. Future work could include installation and extension of the advanced duty detection system. In addition, further modelling and optimisation research could focus on improving the heuristics used for bucket trajectory control, realtime determination of optimum bucket trajectory and testing proposed dragline modifications.

No description available.

All systems are unreliable in the sense that they degrade with age and usage and eventually fail. The degradation depends on the load (or stress) on the system and the maintenance actions. With higher load the productivity increases but this is achieved at the expense of faster degradation and more frequent failures. This in turn reduces the availability of the system. The yield (expected output per unit time), expected operational cost and the expected profit are functions of the load and the availability. The relationship between load and yield is a complicated function and depends on system reliability and maintenance actions. The thesis deals with determining the optimal load and maintenance actions to maximise the yield (or expected profit) or to minimise the expected cost. The thesis comprises of two parts (Parts I and II). Part I is theoretical in nature and looks at the modelling, analysis and optimisation issues. Part II deals with a real case study involving a dragline used in open cut mining. Part I starts with stress-life models which link the load on the system with the reliability of the system. It examines the empirical data in the form of S-N and P-S-N curves, and as WPP plots reported in the literature. The salient features are identified so as to assess the suitability of different models to model the stress-life data. Various Weibull models are assessed to determine their suitability to model stress-life data at the component level. This is followed by a discussion of the modelling at the system level. Optimal maintenance actions are derived based on component level and system level stress-life models. For the component level models, the optimal maintenance actions are derived for a variety of maintenance strategies (such as the age, block and periodic policies) for a specified load to minimise the asymptotic expected cost per unit time. Following this, the joint optimal choice of load and maintenance is examined. For the system level model, the optimal load is obtained to minimise the expected cost per unit time over the life of the system taking into account different actions such as minor and major preventive maintenance actions and corrective maintenance actions. Part II deals with a case study involving a BE1370W dragline. The dragline is used in open cut coal mining to remove the dirt (overburden) on top of the coal seam. This involves dragging the bucket, which is suspended from the boom, through the muckpile until full and then hoisting and swinging the bucket to the dumping point. The capacity of the bucket size determines the load on the dragline. The system level model studied in Part I is used to determine the optimal load to maximise the yield. The dragline was modelled as comprising of 25 components (or sub-systems). Each component was modelled using a system level model of Part I. The model parameters were estimated using real operating and maintenance data over two years. The optimal load to maximise the yield was derived and a sensitivity study carried out.

Spiders are capable of producing a variety of silk types, each with their own unique protein composition and function. Dragline silk in particular, has been of great interest due to its high tensile strength and extensibility. In the past, synthetically produced dragline fibers have not been able to match the superior properties of natural silk. A recent discovery in the western black widow spider, Latrodectus hesperus, might be the missing link between the current state of synthetic silks and naturally produced fibers. Our research is centered around the discovery a new family of five low-molecular-weight cysteine-rich proteins (CRPs) and their potential function within dragline silk. This study focuses on the characterization of recombinantly expressed CRP1, CRP2, and CRP4. Through structural analysis using circular dichroism, it has been determined that the CRP family members have mostly alpha-helical secondary structure and exhibit small differences in their ability to maintain their structure in the presence of changing environmental conditions. The study also covers the effects of temperature and pH on the folding and unfolding of the CRPs. It appears that pH is the dominant influence on protein unfolding within the major ampullate gland.

Spiders spin a wide variety of different silk types with different biological functions that are known for their extraordinary mechanical properties. Dragline silk has predominantly captured the interest of researchers because it exhibits high tensile strength and toughness while maintaining its elasticity. This thesis has focused on the characterization of a family of small molecular weight proteins recently discovered in dragline silk. These proteins were discovered in the western black widow spider, Latrodectus hesperus, and have been termed Cysteine-Rich Proteins (CRPs) due to their high conserved cysteine content. CRP family members were used in protein-protein interaction studies to determine if there is any interaction with the major ampullate spidroins (MaSps). After affinity chromatography and co-expression studies in bacteria, there were no detectable interactions between the CRPs and MaSp1. Further studies which could be an important role in the natural silk assembly process. Further protein interaction studies in different salt and pH conditions can further determine the function of the CRPs in dragline silk formation.

No description available.

The Yellow Rail (Coturnicops noveboracensis) is a migratory nongame bird of high conservation priority throughout its entire range. The objectives of this study were: (1) assess Yellow Rail occupancy in the context of prescribed fire regime in pine savanna habitats of Mississippi and Alabama and (2) assess Yellow Rail habitat use in pine savanna habitats of coastal Mississippi. Yellow Rail occupancy decreased significantly with time since fire and increased with grassland patch size. Throughout the study area Yellow Rail maintained small (mean = 3.37 ha) home ranges aggregated within study areas, indicating suitable habitat may be limited. Yellow Rail used areas dominated by Aristida stricta and Carex spp. They used locations with lower woody percent cover, greater herbaceous height structure and lower frequency of trees than locations outside their home range. This research highlights the continued need to prioritize conservation and management of open grasslands and pine savanna habitats.

Spiders produce a diverse number of silk proteins that are well-known for their extraordinary mechanical and biological properties. Dragline silk has been the most prominent focus of research because of its exceptional high tensile strength and extensibility. In our research, we have focused on the characterization of small molecular weight proteins found within dragline and tubuliform silks. Within the black widow spider, Lactrodectus hesperus, these proteins have been named Cysteine-Rich Protein (CRP) and determined to be a family of five individual proteins. The small protein identified within the tubuliform silks has been named Egg Case Protein 3 (ECP-3). In this study, recombinant expression of ECP-3 in the pET-19b-SUMO vector was to facilitate purification and development of an immunological reagent. Using western blot analysis, we have demonstrated that ECP-3 is efficiently expressed in bacteria. We also investigated CRP1 protein and its ability to bind MaSp1 components using pull down assays to determine potential interactions. No substantial biochemical evidence was produced to demonstrate protein-protein interactions between the two. Additionally, we show that using RT-PCR analysis from mRNAs collected from the major ampullate gland that transcript levels for CRP-family members from non-silked and a silked spider are different. CRP2 and CRP4 mRNA levels were shown to increase upon silking. Overall, the major findings of this thesis involved characterizing the ECP-3 protein found within tubuliform silks as well as determining the expression patterns for CRP-family members.

Spider silk displays a unique balance of high tensile strength and extensibility, making it one of the toughest materials on the planet. Dragline silk, also known as the lifeline of the spider, represents one of the best studied fiber types and many labs are attempting to produce synthetic dragline silk fibers for commercial applications. In these studies, we develop a minifibroin for expression studies in bacteria. Using recombinant DNA methodology and protein expression studies, we develop a natural minifibroin that contains the highly conserved N- and C-terminal domains, along with several internal block repeats of MaSp1. We also characterize a family of small cysteine-rich proteins (CRPs) and demonstrate that these factors are present within the spinning dope of the major ampullate gland using MS analysis. Biochemical studies and characterization of one of the family members, CRP1, demonstrate that this factor can self-polymerize into higher molecular weight complexes under oxidizing conditions, but can be converted into a monomeric species under reducing conditions. Self-polymerization of CRP1 is also shown to be independent of pH and salt concentration, two important chemical cues that help fibroin aggregation. Overall, our data demonstrate that the polymerization state of CRP1 is dependent upon redox state, suggesting that the redox environment during fiber extrusion may help regulate the oligomerization of CRP molecules during dragline silk production.