238 research outputs found

    Metro systems : Construction, operation and impacts

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    Peer reviewedPublisher PD

    Engineered Porous Carbon Adsorbents for Radionuclide Remediation: A Study of Chemical and Physical Factors

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    Accidental release of radioactive material to the environment poses a widespread threat to health of the biosphere, including to humans though contamination of food or water sources, or though inhalation of airborne radioactive particles. The development of targeted, functionalised adsorbents and remediation materials which have the versatility to work effectively in varying groundwater conditions, often containing high quantities of dissolved matter, is necessary. Biopolymers are such a class of materials which are well suited to remediation and immobilisation of contaminants such as radionuclides from groundwater and soil. Not only do they possess promising physicochemical characteristics such as extensive hierarchical porosity, surface functionality and recalcitrance, they are inherently compatible with environmental systems. They can be further functionalised or activated, or incorporated into monolithic composites with specific, engineered functionality and morphology for enhanced uptake and removal of radionuclides. Despite this promise, they are poorly understood at a mechanistic level, in part, due to their amorphous nature which makes analysis of molecular scale processes difficult. Therefore consistent bulk behaviour is more difficult to predict. Understanding the underpinning physical and chemical features of biopolymers and their composites is a crucial step to both further optimisation and deployment of such a material in a remediation setting. Several functionalised biopolymers and monolithic composites were created for strontium uptake and immobilisation. Both the physical and chemical factors governing uptake behaviour were examined. The binding mechanism of strontium was examined using X-ray absorption spectroscopy and paired with bulk strontium uptake isotherm data. High and rapid uptake capacities were achieved to functionalised biochar with even higher uptake achieved to novel biochar-alginate hydrogel composites. EXAFS fitting results indicated biochars and hydrogels alike exhibit an inner sphere binding mechanism to engineered biopolymer adsorbents, indicating strong binding to the adsorbent. Pores, specifically macro pores play a crucial role in mass transport of radionuclides to/from active adsorption sites. They can also prevent pore blocking or fouling during adsorption. The pore architecture of a range of functionalised biochars was investigated quantitatively using X-ray tomography, revealing the pore tuning effect of several common activators on the macro pore space. Each choice of biochar-activator combination yields distinct pore architecture, which can be selected in response to varying application or conditions

    Trend assessment of changing climate patterns over the major agro-climatic zones of Sindh and Punjab

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    The agriculture sector, due to its significant dependence on climate patterns and water availability, is highly vulnerable to changing climate patterns. Pakistan is an agrarian economy with 30% of its land area under cultivation and 93% of its water resources being utilized for agricultural production. Therefore, the changing climate patterns may adversely affect the agriculture and water resources of the country. This study was conducted to assess the climate variations over the major agro-climatic zones of Sindh and Punjab, which serve as an important hub for the production of major food and cash crops in Pakistan. For this purpose, the climate data of 21 stations were analyzed using the Mann–Kendall test and Sen's slope estimator method for the period 1990–2022. The results obtained from the analysis revealed that, in Sindh, the mean annual temperature rose by ~0.1 to 1.4°C, with ~0.1 to 1.2°C in cotton-wheat Sindh and 0.8 to 1.4°C in rice-other Sindh during the study period. Similarly, in Punjab, the mean annual temperature increased by ~0.1 to 1.0°C, with 0.6 to 0.9°C in cotton-wheat Punjab and 0.2 to 0.6°C in rainfed Punjab. Seasonally, warming was found to be highest during the spring season. The precipitation analysis showed a rising annual precipitation trend in Sindh (+30 to +60 mm) and Punjab (+100 to 300 mm), while the monsoon precipitation increased by ~50 to 200 mm. For winter precipitation, an upward trend was found in mixed Punjab, while the remaining stations showed a declining pattern. Conclusively, the warming temperatures as found in the analysis may result in increased irrigation requirements, soil moisture desiccation, and wilting of crops, ultimately leading to low crop yield and threatening the livelihoods of local farmers. On the other hand, the increasing precipitation may favor national agriculture in terms of less freshwater withdrawals. However, it may also result in increased rainfall-induced floods inundating the crop fields and causing water logging and soil salinization. The study outcomes comprehensively highlighted the prevailing climate trends over the important agro-climatic zones of Pakistan, which may aid in devising an effective climate change adaptation and mitigation strategy to ensure the state of water and food security in the country

    Mars delivery service - development of the electro-mechanical systems of the Sample Fetch Rover for the Mars Sample Return Campaign

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    This thesis describes the development of the Sample Fetch Rover (SFR), studied for Mars Sample Return (MSR), an international campaign carried out in cooperation between the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). The focus of this document is the design of the electro-mechanical systems of the rover. After placing this work into the general context of robotic planetary exploration and summarising the state of the art for what concerns Mars rovers, the architecture of the Mars Sample Return Campaign is presented. A complete overview of the current SFR architecture is provided, touching upon all the main subsystems of the spacecraft. For each area, it is discussed what are the design drivers, the chosen solutions and whether they use heritage technology (in particular from the ExoMars Rover) or new developments. This research focuses on two topics of particular interest, due to their relevance for the mission and the novelty of their design: locomotion and sample acquisition, which are discussed in depth. The early SFR locomotion concepts are summarised, covering the initial trade-offs and discarded designs for higher traverse performance. Once a consolidated architecture was reached, the locomotion subsystem was developed further, defining the details of the suspension, actuators, deployment mechanisms and wheels. This technology is presented here in detail, including some key analysis and test results that support the design and demonstrate how it responds to the mission requirements. Another major electro-mechanical system developed as part of this work is the one dedicated to sample tube acquisition. The concept of operations of this machinery was defined to be robust against the unknown conditions that characterise the mission. The design process led to a highly automated robotic system which is described here in its main components: vision system, robotic arm and tube storage

    A Decision Support System for Economic Viability and Environmental Impact Assessment of Vertical Farms

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    Vertical farming (VF) is the practice of growing crops or animals using the vertical dimension via multi-tier racks or vertically inclined surfaces. In this thesis, I focus on the emerging industry of plant-specific VF. Vertical plant farming (VPF) is a promising and relatively novel practice that can be conducted in buildings with environmental control and artificial lighting. However, the nascent sector has experienced challenges in economic viability, standardisation, and environmental sustainability. Practitioners and academics call for a comprehensive financial analysis of VPF, but efforts are stifled by a lack of valid and available data. A review of economic estimation and horticultural software identifies a need for a decision support system (DSS) that facilitates risk-empowered business planning for vertical farmers. This thesis proposes an open-source DSS framework to evaluate business sustainability through financial risk and environmental impact assessments. Data from the literature, alongside lessons learned from industry practitioners, would be centralised in the proposed DSS using imprecise data techniques. These techniques have been applied in engineering but are seldom used in financial forecasting. This could benefit complex sectors which only have scarce data to predict business viability. To begin the execution of the DSS framework, VPF practitioners were interviewed using a mixed-methods approach. Learnings from over 19 shuttered and operational VPF projects provide insights into the barriers inhibiting scalability and identifying risks to form a risk taxonomy. Labour was the most commonly reported top challenge. Therefore, research was conducted to explore lean principles to improve productivity. A probabilistic model representing a spectrum of variables and their associated uncertainty was built according to the DSS framework to evaluate the financial risk for VF projects. This enabled flexible computation without precise production or financial data to improve economic estimation accuracy. The model assessed two VPF cases (one in the UK and another in Japan), demonstrating the first risk and uncertainty quantification of VPF business models in the literature. The results highlighted measures to improve economic viability and the viability of the UK and Japan case. The environmental impact assessment model was developed, allowing VPF operators to evaluate their carbon footprint compared to traditional agriculture using life-cycle assessment. I explore strategies for net-zero carbon production through sensitivity analysis. Renewable energies, especially solar, geothermal, and tidal power, show promise for reducing the carbon emissions of indoor VPF. Results show that renewably-powered VPF can reduce carbon emissions compared to field-based agriculture when considering the land-use change. The drivers for DSS adoption have been researched, showing a pathway of compliance and design thinking to overcome the ‘problem of implementation’ and enable commercialisation. Further work is suggested to standardise VF equipment, collect benchmarking data, and characterise risks. This work will reduce risk and uncertainty and accelerate the sector’s emergence

    PROCEEDINGS 5th PLATE Conference

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    The 5th international PLATE conference (Product Lifetimes and the Environment) addressed product lifetimes in the context of sustainability. The PLATE conference, which has been running since 2015, has successfully been able to establish a solid network of researchers around its core theme. The topic has come to the forefront of current (political, scientific & societal) debates due to its interconnectedness with a number of recent prominent movements, such as the circular economy, eco-design and collaborative consumption. For the 2023 edition of the conference, we encouraged researchers to propose how to extend, widen or critically re-construct thematic sessions for the PLATE conference, and the paper call was constructed based on these proposals. In this 5th PLATE conference, we had 171 paper presentations and 238 participants from 14 different countries. Beside of paper sessions we organized workshops and REPAIR exhibitions

    Developing silicon pixel detectors for LHCb: constructing the VELO Upgrade and developing a MAPS-based tracking detector

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    The Large Hadron Collider beauty (LHCb) experiment is currently undergoing a major upgrade of its detector, including the construction of a new silicon pixel detector, the Vertex Locator (VELO) Upgrade. The challenges faced by the LHCb VELO Upgrade are discussed, and the design to overcome them is presented. VELO modules have been produced at the University of Manchester. The VELO modules use 55 μ\mum pixels operating 5.1 mm from the beam without a beam pipe, an innovative silicon microchannel cooling substrate, and 40 MHz readout with a full detector bandwidth of 3 Tb/s. The module assembly process and the results of the associated R&D are presented. The mechanical and electronic tests are described. A grading scheme for each test is described, and the results are presented. The majority of the modules are of excellent quality, with 40 out of 43 of suitable quality for installation in the experiment. A full set of modules for the experiment has now been produced. The VELO Upgrade is read out into a data acquisition system based on an FPGA board. The architecture of the readout firmware for the readout FPGA for the VELO Upgrade is presented, and the function of each block described. Challenges arise due to the design of the VeloPix front end chip, the fully-software trigger and real-time analysis paradigm. These challenges are discussed and their solutions briefly described. An algorithm for identifying isolated clusters is presented and previously-considered approaches discussed. The current design uses around 83 % of the available logic blocks, and 85 % of the available memory blocks. A complete version of the firmware is now available and is being refined. An ultimate version of the LHCb experiment, the LHCb Upgrade II, is being designed for the 2030s to fully exploit the potential of the high luminosity LHC. The Mighty Tracker is the proposed new combined-technology downstream tracker for Upgrade II, consisting of a silicon pixel inner region and a scintillating fibre outer region. A potential layout of the detector and modules is given. The silicon pixels will likely be the first LHC tracker based on radiation-hard HV-MAPS technology. Studies for the electronic readout system of the silicon inner region are reported. The total bandwidth and its distribution across the tracker are discussed. The numbers of key readout and FPGA DAQ boards are calculated. The detector's expected data rate is 8.13 Tb/s in Upgrade II conditions over a total of more than 46,000 front end chips

    Wheat Improvement

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    This open-access textbook provides a comprehensive, up-to-date guide for students and practitioners wishing to access in a single volume the key disciplines and principles of wheat breeding. Wheat is a cornerstone of food security: it is the most widely grown of any crop and provides 20% of all human calories and protein. The authorship of this book includes world class researchers and breeders whose expertise spans cutting-edge academic science all the way to impacts in farmers’ fields. The book’s themes and authors were selected to provide a didactic work that considers the background to wheat improvement, current mainstream breeding approaches, and translational research and avant garde technologies that enable new breakthroughs in science to impact productivity. While the volume provides an overview for professionals interested in wheat, many of the ideas and methods presented are equally relevant to small grain cereals and crop improvement in general. The book is affordable, and because it is open access, can be readily shared and translated -- in whole or in part -- to university classes, members of breeding teams (from directors to technicians), conference participants, extension agents and farmers. Given the challenges currently faced by academia, industry and national wheat programs to produce higher crop yields --- often with less inputs and under increasingly harsher climates -- this volume is a timely addition to their toolkit

    Engaging Students in Sustainable Science Education

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    This Special Issue (Engaging Students in Sustainable Science Education) compiled effective approaches to student engagement in science-related classes. Some articles were written by researchers in science education; however, the majority were prepared by college and university instructors based on their own instructional approaches, and were designed to help other practitioners improve student engagement in scientific contexts. Both types of contributors added value to this conversation. This Special Issue serves to unite science and education, identifying approaches that create stimulating scientific learning environments
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