Optimisation for Large-scale Maintenance, Scheduling and Vehicle Routing Problems

Solving real-world combinatorial problems is involved in many industry fields to minimise operational cost or to maximise profit, or both. Along with continuous growth in computing power, many asset management decision-making processes that were originally solved by hand now tend to be based on big data analysis. Larger scale problem can be solved and more detailed operation instructions can be delivered. In this thesis, we investigate models and algorithms to solve large scale Geographically Distributed asset Maintenance Problems (GDMP). Our study of the problem was motivated by our business partner, Gaist solutions Ltd., to optimise scheduling of maintenance actions for a drainage system in an urban area. The models and solution methods proposed in the thesis can be applied to many similar issues arising in other industry fields. The thesis contains three parts. We firstly built a risk driven model considering vehicle routing problems and the asset degradation information. A hyperheuristic method embedded with customised low-level heuristics is employed to solve our real-world drainage maintenance problem in Blackpool. Computational results show that our hyperheuristic approach can, within reasonable CPU time, produce much higher quality solutions than the scheduling strategy currently implemented by Blackpool council. We then attempt to develop more efficient solution approaches to tackle our GDMP. We study various hyperheuristics and propose efficient local search strategies in part II. We present computational results on standard periodic vehicle routing problem instances and our GDMP instances. Based on manifold experimental evidences, we summarise the principles of designing heuristic based solution approaches to solve combinatorial problems. Last bu not least, we investigate a related decision making problem from highway maintenance, that is again of interest to Gaist solutions Ltd. We aim to make a strategical decision to choose a cost effective method of delivering the road inspection at a national scale. We build the analysis based on the Chinese Postman Problem and theoretically proof the modelling feasibility in real-world road inspection situations. We also propose a novel graph reduction process to allow effective computation over very large data sets

Irrigation is more than irrigating: agricultural green water interventions contribute to blue water depletion and the global water crisis

Reflecting on the 2023 assertion by the Global Commission on the Economics of Water that the depletion of blue water by irrigation contributes to the global water crisis, we critique two previous contributions by one of its authors, Johan Rockström. First, to bridge agro-meteorological drought, rainfed (green water) farmers should irrigate. If not regulated, this increases water withdrawals and depletion. Second, the continuum of agricultural water management is a field-scale emphasis on rainfall and/or irrigating to top up soil moisture. This emphasis hinders taking a multi-scale irrigation systems approach to resolve blue water depletion and its inequitable impacts

Development of Geospatial Models for Multi-Criteria Decision Making in Traffic Environmental Impacts of Heavy Vehicle Freight Transportation

Heavy vehicle freight transportation is one of the primary contributors to the socio-economic development, but it has great influence on traffic environment. To comprehensively and more accurately quantify the impacts of heavy vehicles on road infrastructure performance, a series of geospatial models are developed for both geographically global and local assessment of the impacts. The outcomes are applied in flexible multi-criteria decision making for the industrial practice of road maintenance and management

Extent of Salt Affected Land in Central Asia: Biosaline Agriculture and Utilization of the Salt-affected Resources

The current status and trends of salinization are discussed with waterlogging of marginal land/plant and water resources problems including strategies for development of integrated biosaline crop-livestock agriculture based system on food-feed crops and forage legumes for better livelihood of poor farmers in Central Asian (Uzbekistan, Kazakhstan, Turkmenistan and Tajikistan). Transfer of technologies and/or methodology of ICBA (International Centre for Biosaline Agriculture) in planting of both perennial and annual valuable halophytes (based on around the world dataset from similar sites and conditions) are a new approach that should be tested in Central Asia. Afforestation, as an option to mitigate land degradation, requires a judicious evaluation and selection of multipurpose tree species (MPTS) to make use of marginal unproductive/salt- affected lands and lower the elevated groundwater table (GWT) via biodrainage. The leading among 21 screened native and introduced tree and shrubs species with regards to survival rate, growth characteristics and adaptability to high saline natural environment proved to be Haloxylon apphyllum, Salsola paletzkiana, S. richteri at the saline sandy deserts, followed by atriplex undulate, Hippophae ramnoides, E. angustifolia, Acacia ampliceps, U. pumila, P. euphratica and P. nigra var. pyramidalis, Robinia pseudoacacia, M. alba, Morus nigra on clay loamy hyromorphic soils, whereas fruit species such as Cynadon oblonga, Armeniaca vulgare, Prunus armeniaca and species of genera Malus, though desirable from the farmer's financial viewpoint, showed low bio drainage potential. Planting herbaceous fodder crops within the inter-spaces of fodder salt tolerant trees and shrubs on intensive agro-forestry plantations could solve the animal feeding problem in the degraded (both by overgrazing and salinity) desert and semidesert marginal areas. Yield data of new varieties of sorghum and pearl millet ICBA/ICRISAT germplasm collected at the conclusion of the 2006-2007 growing seasons indicates considerable adaptability of introduced genetic material to saline soil conditions, when compared to local material. Sorghum and pearl millet crop residues utilization could be an option for bio fuel production in the region.

Proceedings of 2013 Kentucky Water Resources Annual Symposium

This symposium was planned and conducted as a part of the state water resources research institute annual program that is supported by Grant/Cooperative Agreement Number G11AP20081 from the United States Geological Survey. The contents of this proceedings document and the views and conclusions presented at the symposium are solely the responsibility of the individual authors and presenters and do not necessarily represent the official views of the USGS or of the symposium organizers and sponsors. This publication is produced with the understanding that the United States Government is authorized to reproduce and distribute reprints for government purposes

Simulation and optimization model for the construction of electrical substations

One of the most complex construction projects is electrical substations. An electrical substation is an auxiliary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers. Construction of electrical substation includes civil works and electromechanical works. The scope of civil works includes construction of several buildings/components divided into parallel and overlapped working phases that require variety of resources and are generally quite costly and consume a considerable amount of time. Therefore, construction of substations faces complicated time-cost-resource optimization problems. On another hand, the construction industry is turning out to be progressively competitive throughout the years, whereby the need to persistently discover approaches to enhance construction performance. To address the previously stated afflictions, this dissertation makes the underlying strides and introduces a simulation and optimization model for the execution processes of civil works for an electrical substation based on database excel file for input data entry. The input data include bill of quantities, maximum available resources, production rates, unit cost of resources and indirect cost. The model is built on Anylogic software using discrete event simulation method. The model is divided into three zones working in parallel to each other. Each zone includes a group of buildings related to the same construction area. Each zone-model describes the execution process schedule for each building in the zone, the time consumed, percentage of utilization of equipment and manpower crews, amount of materials consumed and total direct and indirect cost. The model is then optimized to mainly minimize the project duration using parameter variation experiment and genetic algorithm java code implemented using Anylogic platform. The model used allocated resource parameters as decision variables and available resources as constraints. The model is verified on real case studies in Egypt and sensitivity analysis studies are incorporated. The model is also validated using a real case study and proves its efficiency by attaining a reduction in model time units between simulation and optimization experiments of 10.25% and reduction in total cost of 4.7%. Also, by comparing the optimization results by the actual data of the case study, the model attains a reduction in time and cost by 13.6% and 6.3% respectively. An analysis to determine the effect of each resource on reduction in cost is also presented

Valuing archaeology; exploring the reality of the heritage management of England’s wetlands

BursaryThis work primarily examines the management of wet-preserved archaeological sites in England, through an exploration of value and analysis of current management approaches. The aim is to explore whether the current policy frameworks, in particular the role of preservation in situ, can provide a sustainable future for wet-preserved archaeological sites. This work further seeks to conceptualise the modelling of sustainability, preservation and management decision making in wetland archaeological sites. Looking at the last 40 year of wetland research through the work of the large-scale wetland survey projects, this work initially considers the current understanding of wet archaeological sites in England. It also examines aspects of heritage management through the legislative and policy frameworks and their legacy. This work considers the implications that legislative and policy positions have for the management of wetland archaeological sites and examines the theoretical concepts that underpin them. This includes exploring reflective management, the development of research frameworks, and scoring mechanisms for the designation of sites. It also looks at broader constructs of value through the concepts of cultural and economic values. Three existing archaeological sites, a ringwork at Borough Fen near Peterborough, a marsh fort at Sutton Common near Doncaster and a triple post-alignment near Beccles, will be presented as case studies. These sites serve as examples of how the management of sites has been approached. The results of the case study analysis are used to develop a series of conceptual models looking firstly at sustainability and preservation in situ, and, secondly at preservation, value and decision making. The study concludes that the presumption in favour of preservation in situ can be challenging for wet preserved archaeological sites. Deterioration of the preservation environment can in some cases produce a similar decline in significance. Preservation in situ may therefore not be the most appropriate option for archaeological sites in wetlands.University of Exete

Urban hydroinformatics: past, present and future

This is the author accepted manuscriptHydroinformatics, as an interdisciplinary domain that blurs boundaries between water science, data science and computer science, is constantly evolving and reinventing itself. At the heart of this evolution, lies a continuous process of critical (self) appraisal of the discipline’s past, present and potential for further evolution, that creates a positive feedback loop between legacy, reality and aspirations. The power of this process is attested by the successful story of hydroinformatics thus far, which has arguably been able to mobilize wide ranging research and development and get the water sector more in tune with the digital revolution of the past 30 years. In this context, this paper attempts to trace the evolution of the discipline, from its computational hydraulics origins to its present focus on the complete socio-technical system, by providing at the same time, a functional framework to improve the understanding and highlight the links between different strands of the state-of-art hydroinformatic research and innovation. Building on this state-of-art landscape, the paper then attempts to provide an overview of key developments that are coming up, on the discipline’s horizon, focusing on developments relevant to urban water management, while at the same time, highlighting important legal, ethical and technical challenges that need to be addressed to ensure that the brightest aspects of this potential future are realized. Despite obvious limitations imposed by a single paper’s ability to report on such a diverse and dynamic field, it is hoped that this work contributes to a better understanding of both the current state of hydroinformatics and to a shared vision on the most exciting prospects for the future evolution of the discipline and the water sector it serves

Modelling the agronomic and environmental impacts of irrigation management on turfgrass for golf greens in northern europe.

Irrigation is an essential component of turfgrass management for golf. During dry periods, it helps maintain turf health, stimulates nitrogen uptake, promotes germination, reduces canopy temperature, as well as assures high standards of quality for playability. In recent years, rising competition for water coupled with new environmental regulations has exerted pressure on water allocations for golf. Improving water efficiency and water management in golf have become major industry priorities. The aim of this thesis was to understand and asses the relationships between irrigation management and turfgrass water use, soil water availability, dry matter production, drainage and nitrate leaching in golf greens under Northern European climate conditions. The research combined published science and industry evidence with field and experimental data, in order to calibrate and validate an irrigation ballistics-based model and a biophysical crop model (STICS). From this, an integrated model (BalliSTICS) was developed and used to simulate the impacts of irrigation uniformity on turfgrass growth and development and leaching risks, under contrasting management and climate scenario. The modelling showed that system design plays a crucial role in achieving high irrigation uniformity, particularly sprinkler position and spacing. A larger spacing between sprinklers resulted in a decrease in irrigation rates and a significant decrease in uniformity, particularly when wind speeds exceeded 2 m s-1. Surprisingly, the range of pressure and nozzle sizes investigated did not significantly impact on irrigation uniformity. Non-uniform irrigation was found to have a considerable impact on the spatial variability in turf growth, soil moisture content, drainage and leaching. Under northern European climate conditions, irrigation strategy had a more significant impact on turfgrass response than irrigation uniformity. A moderate deficit strategy (replacement of 60% potential evapotranspiration) was sufficient to achieve the highest growth values (233 ± 10.6 g m-² season¯¹). This strategy resulted in not only a reduction of irrigation water use but also minimised the amount of nitrate leached in drainage. However, an inadequate irrigation schedule combined with poor irrigation uniformity (CU < 60%) led to a threefold increase in water use, and an average 114% and 50% increase in drainage and nitrate leaching, respectively. Inadequate irrigation practices had little impact on turfgrass growth, which could be misleading as excessive irrigation might not affect plant growth and visual quality but would mask poor irrigation uniformities, lead to excessive water use and an increase in risks of groundwater contamination from leaching. The research provides valuable and novel insights into better understanding the combined impacts of irrigation performance and management on turfgrass. The findings will support greenkeepers and the turfgrass industry and increase awareness of the importance of irrigation