Quantifying the potential for reservoirs to secure future surface water yields in the world's largest river basins

Surface water reservoirs provide us with reliable water supply, hydropower generation, flood control and recreation services. Yet, reservoirs also cause flow fragmentation in rivers and lead to flooding of upstream areas, thereby displacing existing land-use activities and ecosystems. Anticipated population growth and development coupled with climate change in many regions of the globe suggests a critical need to assess the potential for future reservoir capacity to help balance rising water demands with long-term water availability. Here, we assess the potential of large-scale reservoirs to provide reliable surface water yields while also considering environmental flows within 235 of the world’s largest river basins. Maps of existing cropland and habitat conservation zones are integrated with spatially-explicit population and urbanization projections from the Shared Socioeconomic Pathways (SSP) to identify regions unsuitable for increasing water supply by exploiting new reservoir storage. Results show that even when maximizing the global reservoir storage to its potential limit (~4.3-4.8 times the current capacity), firm yields would only increase by about 50% over current levels. However, there exist large disparities across different basins. The majority of river basins in North America are found to gain relatively little firm yield by increasing storage capacity, whereas basins in Southeast Asia display greater potential for expansion as well as proportional gains in firm yield under multiple uncertainties. Parts of Europe, the United States and South America show relatively low reliability of maintaining current firm yields under future climate change, whereas most of Asia and higher latitude regions display comparatively high reliability. Findings from this study highlight the importance of incorporating different factors, including human development, land-use activities, and climate change, over a time span of multiple decades and across a range of different scenarios when quantifying available surface water yields and the potential for reservoir expansion

The MESSAGEix Integrated Assessment Model and the ix modeling platform (ixmp)

The MESSAGE Integrated Assessment Model (IAM) developed by IIASA has been a central tool of energy-environment-economy systems analysis in the global scientific and policy arena. It played a major role in the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC); it provided marker scenarios of the Representative Concentration Pathways (RCPs) and the Shared Socio-Economic Pathways (SSPs); and it underpinned the analysis of the Global Energy Assessment (GEA). Alas, to provide relevant analysis for current and future challenges, numerical models of human and earth systems need to support higher spatial and temporal resolution, facilitate integration of data sources and methodologies across disciplines, and become open and transparent regarding the underlying data, methods, and the scientific workflow. In this manuscript, we present the building blocks of a new framework for an integrated assessment modeling platform; the \ecosystem" comprises: i) an open-source GAMS implementation of the MESSAGE energy++ system model integrated with the MACRO economic model; ii) a Java/database backend for version-controlled data management, iii) interfaces for the scientific programming languages Python & R for efficient input data and results processing workflows; and iv) a web-browser-based user interface for model/scenario management and intuitive \drag-and-drop" visualization of results. The framework aims to facilitate the highest level of openness for scientific analysis, bridging the need for transparency with efficient data processing and powerful numerical solvers. The platform is geared towards easy integration of data sources and models across disciplines, spatial scales and temporal disaggregation levels. All tools apply best-practice in collaborative software development, and comprehensive documentation of all building blocks and scripts is generated directly from the GAMS equations and the Java/Python/R source code

Experimental Analysis of Mechanical Seal Design with Enhanced Thermal Performance

For industries that use pumps and mixers in their process operations, it is of paramount importance to control the leakage from these equipments. The leakage presents safety hazards and economic loss. It is widely believed that the majority of downtime associated with a pump or a mixer is the result of a mechanical seal failure. Therefore, it is important for these industries to have a mechanical seal that is a reliable performer and enables a longer operational life than what exist in the market at present. The aim of this research was to design and test a mating ring with superior thermal performance that could be used in the conventional seal arrangement without modification to the existing arrangement. The new design was called Fin Mating Ring. The design had radial fins on its circumference and it could replace an existing conventional mating ring without modification to the gland. This thesis contains both an analytical and experimental phases associated with the performance of the new design. Different designs were created and optimized by using Finite Element Analysis (ANSYS). The performances of the new designs are compared with the heat transfer characteristics of the conventional design. Experimental measurements of temperature, flow rates, and pressure in both the new mechanical seal design and the existing conventional seal were performed. Both were tested using the same flow, pressure, rotational velocity and coolant (flush). The test results revealed that the temperatures measured in the new design (Fin Mating Ring) were lower than the conventional ring. Therefore, the fin mating ring design had superior heat transfer characteristic that the existing conventional mating ring. Due to the lower surface temperatures, the fin mating ring design is expected to have a lower wear rate than the conventional ring and sustain a longer seal life

A methodology for determining the dynamic exchange of resources in nuclear fuel cycle simulation

Simulation of the nuclear fuel cycle can be performed using a wide range of techniques and methodologies. Past efforts have focused on specific fuel cycles or reactor technologies. The CYCLUS fuel cycle simulator seeks to separate the design of the simulation from the fuel cycle or technologies of interest. In order to support this separation, a robust supply–demand communication and solution framework is required. Accordingly an agent-based supply-chain framework, the Dynamic Resource Exchange (DRE), has been designed implemented in CYCLUS. It supports the communication of complex resources, namely isotopic compositions of nuclear fuel, between fuel cycle facilities and their managers (e.g., institutions and regions). Instances of supply and demand are defined as an optimization problem and solved for each timestep. Importantly, the DRE allows each agent in the simulation to independently indicate preference for specific trading options in order to meet both physics requirements and satisfy constraints imposed by potential socio-political models. To display the variety of possible simulations that the DRE enables, example scenarios are formulated and described. Important features include key fuel-cycle facility outages, introduction of external recycled fuel sources (similar to the current mixed oxide (MOX) fuel fabrication facility in the United States), and nontrivial interactions between fuel cycles existing in different regions

Opening the black box of energy modelling: Strategies and lessons learned

The global energy system is undergoing a major transition, and in energy planning and decision-making across governments, industry and academia, models play a crucial role. Because of their policy relevance and contested nature, the transparency and open availability of energy models and data are of particular importance. Here we provide a practical how-to guide based on the collective experience of members of the Open Energy Modelling Initiative (Openmod). We discuss key steps to consider when opening code and data, including determining intellectual property ownership, choosing a licence and appropriate modelling languages, distributing code and data, and providing support and building communities. After illustrating these decisions with examples and lessons learned from the community, we conclude that even though individual researchers' choices are important, institutional changes are still also necessary for more openness and transparency in energy research

Super-resolution imaging of proteins in live cells using reversibly interacting peptide pairs

Super-resolution techniques have revolutionised our ability to observe cellular structures with significantly higher resolution than traditional microscopy. Despite the number of super-resolution microscopy techniques available, live cell super-resolution imaging remains challenging. For example, while Photo-activated localisation microscopy (PALM) can be used in vivo, it necessitates the direct fusion of a fluorophore to the protein of interest. This approach can be problematic because a direct fusion to a fluorescent protein can disrupt the normal function and localisation of the protein being studied. Moreover, once the fluorescent protein is photobleached, no more data can be collected from that molecule. In this thesis, I describe the development and use of LIVE-PAINT, a novel live-cell super-resolution microscopy technique. In LIVE-PAINT, a peptide-protein or peptidepeptide pair, one fused to the protein of interest and the other to a fluorescent protein, reversibly interact. When the peptide pair bind, a blink is observed, and the precise location can be determined. In a few minutes, enough binding events occur to generate an image of the protein of interest with a resolution of around 20 nanometres. Initially, this work optimises and applies LIVE-PAINT for diffraction-limited and super-resolution imaging of proteins within live budding yeast cells. I then demonstrate that the small peptide tag used to label the protein of interest makes LIVE-PAINT a valuable tool for imaging proteins that are sensitive to direct fusions to fluorescent proteins. In addition, I validate that LIVE-PAINT enables replenishment of signal throughout imaging. This is because the imaging peptide, the peptide-labelled fluorescent protein, is expressed separately from the target protein, creating a pool of imaging peptides within the cell that can replenish those that are photobleached during imaging. I utilise this property of LIVE-PAINT to track moving proteins over long periods of time. Subsequently, I describe how I adapted the LIVE-PAINT system to apply this technique to the more complex environment of live mammalian cells. I show that LIVE-PAINT successfully yields diffraction-limited and super-resolution images of proteins located in various organelles. This is the first time that interacting peptide pairs have been used to facilitate point accumulation for imaging in nanoscale topography (PAINT) based super-resolution imaging in live mammalian cells. These results are obtained through both transient transfections of labelled proteins and stably integrated versions. Through this work I generate several new cell lines which can be shared with other researchers allowing them to use this technique to gain new insights into the proteins they study. Furthermore, this thesis explores improvements to the LIVE-PAINT method. I demonstrate that peptides as small as 5 residues can be used for LIVE-PAINT imaging. This will broaden the applicability of LIVE-PAINT to a wider range of proteins that cannot tolerate modifications. To harness the increased brightness of synthetic fluorescent dyes compared to fluorescent proteins, I developed mammalian cell lines expressing a HaloTag fused to a LIVE-PAINT peptide. I show that the exogenous addition of the binding partner to HaloTag, HaloLigand, labelled with a synthetic dye, to these cells, enables LIVE-PAINT imaging with synthetic dyes. Lastly, I validate that LIVE-PAINT can be multiplexed by using orthogonal peptide-protein pairs to image two proteins concurrently in live cells. In summary, this thesis presents the development and optimisation of LIVE-PAINT, an innovative peptide-based super-resolution imaging technique tailored for live cell imaging. While this work explores select applications of LIVE-PAINT, it is anticipated that this novel technique will have a broad spectrum of applications

Closing the gap: the impact of G20 climate commitments on limiting global temperature rise to 1.5°C

Under the Paris Agreement, Parties agreed to limit global temperature rise to well below 2°C, and pursue efforts to limit warming to 1.5°C. While some progress has been made in strengthening national climate targets and policies, current nationally national for reducing emissions are still insufficient to meet the Paris Agreement's temperature goal. Strengthened 2030 and mid-century commitments are urgently needed. The G20—a group collectively accounting for around 75 percent of global greenhouse gas (GHG) emissions, 80 percent of global GDP, and two-thirds of global population—has an outsized role to play in addressing climate change.This paper presents a set of scenarios that simulate different climate commitments made by G20 countries for 2030 and mid-century and the resulting impacts on global temperature rise. The analysis finds that if all G20 countries set ambitious, 1.5°C-aligned emission reduction targets for 2030 and reach net-zero emissions by 2050, global temperature rise at the end of the century could be limited to 1.7°C, keeping the 1.5°C goal within reach.