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Power system resource adequacy (RA), or its ability to continually balance energy supply and demand, underpins human and economic health. How meteorology affects RA and RA failures, particularly with increasing penetrations of renewables, is poorly understood. We characterize large-scale circulation patterns that drive RA failures in the Western U.S. at increasing wind and solar penetrations by integrating power system and synoptic meteorology methods. At up to 60% renewable penetration and across analyzed weather years, three high pressure patterns drive nearly all RA failures. The highest pressure anomaly is the dominant driver, accounting for 20-100% of risk hours and 43-100% of cumulative risk at 60% renewable penetration. The three high pressure patterns exhibit positive surface temperature anomalies, mixed surface solar radiation anomalies, and negative wind speed anomalies across our region, which collectively increase demand and decrease supply. Our characterized meteorological drivers align with meteorology during the California 2020 rolling blackouts, indicating continued vulnerability of power systems to these impactful weather patterns as renewables grow. Sundar and colleagues characterize large-scale circulation patterns that drive resource adequacy failures in the Western U.S. at increasing wind and solar penetrations by integrating power system and synoptic meteorology methods. They find that at 60% renewable penetration and across analyzed weather years, three high pressure patterns drive nearly all resource adequacy failures.

Climate change threatens the resource adequacy of future power systems. Existing research and practice lack frameworks for identifying decarbonization pathways that are robust to climate‐related uncertainty. We create such an analytical framework, then use it to assess the robustness of alternative pathways to achieving 60% emissions reductions from 2022 levels by 2040 for the Western U.S. power system. Our framework integrates power system planning and resource adequacy models with 100 climate realizations from a large climate ensemble. Climate realizations drive electricity demand; thermal plant availability; and wind, solar, and hydropower generation. Among five initial decarbonization pathways, all exhibit modest to significant resource adequacy failures under climate realizations in 2040, but certain pathways experience significantly less resource adequacy failures at little additional cost relative to other pathways. By identifying and planning for an extreme climate realization that drives the largest resource adequacy failures across our pathways, we produce a new decarbonization pathway that has no resource adequacy failures under any climate realizations. This new pathway is roughly 5% more expensive than other pathways due to greater capacity investment, and shifts investment from wind to solar and natural gas generators. Our analysis suggests modest increases in investment costs can add significant robustness against climate change in decarbonizing power systems. Our framework can help power system planners adapt to climate change by stress testing future plans to potential climate realizations, and offers a unique bridge between energy system and climate modeling. Plain Language Summary Over the past few years, large power outage events in California and Texas have underscored the vulnerability of our power systems to extreme weather. By increasing the intensity and frequency of extreme weather, climate change could lead to more power outages. In response, power system planners are grappling with how to plan for extreme weather and climate change when making investment decisions, such as in wind and solar power. In our research, we build and apply a new analytical framework for making power system investment decisions under climate change. Our framework draws on a hundred realizations of future climate, and integrates weather in those realizations with power system models that make investment decisions and explore the risk of power outages. We find five alternative investment pathways all could suffer from moderate to significant power outages under possible climate realizations by 2040. But by identifying what realizations drive outage risk in these pathways, we construct a new pathway that does not exhibit outage risks to our future climate realizations. Overall, these insights demonstrate the value of our new analytical framework for making better investment decisions under uncertainty posed by climate change. Key Points We identify a decarbonization pathway for the power system that is robust to future climate realizations Our framework is extensible to long‐term planning by utilities, regions, and regulators Large climate ensembles expose significant resource adequacy vulnerabilities in alternative decarbonization pathways

Decarbonization of the electrical power system is essential to restrict global warming and mitigate the worst impacts of climate change. Maintaining resource adequacy, i.e., the system’s ability to continuously balance supply and demand, is essential for system reliability. Failures in power system reliability, i.e., power outages, can cause large socio-economic impacts. As decarbonization reshapes electricity supply and demand, meteorology will increasingly drive system reliability. We are already seeing the compounding impacts of these changes, exemplified by the widespread outage events in California. System practitioners need to ensure that the planning process accounts for high penetrations of variable renewable generation along with changes in meteorological systems caused by climate change. With the Western U.S. power system as the study system, in each chapter of this thesis, I address these needs by studying the linkages between the energy system and the meteorological system. My primary contributions include the discovery of salient meteorology driving large scale resource adequacy failures and utilizing the robust decision making framework to identify decarbonization pathways that are robust to future climate uncertainty. In chapter 2, I study how meteorology affects resource adequacy and resource adequacy failures, particularly with increasing penetrations of renewables. I characterize large-scale circulation patterns that drive RA failures in the Western U.S. at increasing wind and solar penetrations by integrating power system and synoptic meteorology methods. At up to 60% renewable penetration and across analyzed weather years, I find three high pressure patterns drive nearly all RA failures. The highest pressure anomaly is the dominant driver, accounting for 20-100% of risk hours and 43-100% of cumulative risk at 60% renewable penetration. The three high pressure patterns exhibit positive surface temperature anomalies, mixed surface solar radiation anomalies, and negative wind speed anomalies across our region, which collectively increase demand and decrease supply. The meteorological drivers we characterize align with meteorology during the California 2020 rolling blackouts, indicating continued vulnerability of power systems to these impactful weather patterns as renewables grow.In chapter 3, I use the robust decision making framework to find decarbonization pathways which are robust against deep climate uncertainty. Here, I use the multiple future climate realizations embedded in the CESM2-large ensemble climate data set to account for this climate uncertainty. I build future fleets for different decarbonization pathways based on emission constraints in 2040. I evaluate the resource adequacy of these fleets against the climate realizations using surplus available capacity. I find that the resource adequacy of high decarbonization pathways are more robust to climate change in the Desert Southwest and Pacific Northwest regions than low decarbonization pathways. In 2040, for the the high decarbonization pathways result in greater resource adequacy than low decarbonization pathways in 94% of the scenarios modeled in California region, 100% of the scenarios modeled in Desert Southwest region, and 99% of scenarios modeled in the Pacific Northwest region. The high decarbonization pathways also lead to a diversification of risk occurrence in California and Northwest, with risk of system failure shifting from summer and fall seasons to the winter season under many future potential climates. Future studies can use this framework to identify climate realizations which lead to worst outcomes across decarbonization pathways.

The paper demonstrates the use of variational autoencoders for graphical representation of a large database containing process-microstructure relationships. Correlating microstructural features to processing is an essential first step to answer the difficult problem of process sequence design. In this paper, a large database of 346,200 orientation distribution functions resulting from a variety of process sequences is constructed, where each sequence comprises up to four stages of tension, compression and rolling along different directions in various permutations. This opensource database is constructed for collaborative development of process design algorithms. The paper demonstrates a novel application of the large database: graphical representation of texture-process relationships. A variational autoencoder is used to reduce the entire database to a two dimensional latent space where variations in processes and properties can be visualized. Using proximity analysis in this latent space, we can quickly unearth multiple process solutions to the problem of texture or property design.

Amorphous SnO–Sb 2 O 3 –SiO 2 glass anode prepared by simple mechanical ball milling method. Physical and electrochemical properties of prepared glass anode identified by X-ray powder diffraction (XRD), scanning electron microscopy, cyclic voltammetry, galvanostatic, and electrochemical impedance spectroscopy (EIS) techniques. Amorphous nature of SnO–Sb 2 O 3 –SiO 2 60 h of ball-milled glass anode confirmed by XRD technique. The glass anode showed excellent electrochemical performance up to 100 cycles in the voltage range between 0 and 3.0 V. Cycle performance tests showed that the anode delivered a specific discharge and charge capacity of 782 and 654 mAh g −1 with 100% columbic efficiency about 100 cycles at 0.5 C rate. Its shows ~ 99% capacity retention even at a high-capacity rate of 5 C with a current density of 258 mAh g −1 . The EIS spectroscopy revealed that the charge transfer resistance ( R ct ) decreasing to an increasing cycle number which ascribed to superior conductivity of glass anode. This research contributed to the development of a large-scale preparation procedure for high-performance SnO–Sb 2 O 3 –SiO 2 glass anode materials for use in Na-ion batteries.

SummaryBackgroundTemporary drug treatment cessation might alleviate toxicity without substantially compromising efficacy in patients with cancer. We aimed to determine if a tyrosine kinase inhibitor drug-free interval strategy was non-inferior to a conventional continuation strategy for first-line treatment of advanced clear cell renal cell carcinoma. MethodsThis open-label, non-inferiority, randomised, controlled, phase 2/3 trial was done at 60 hospital sites in the UK. Eligible patients (aged ≥18 years) had histologically confirmed clear cell renal cell carcinoma, inoperable loco-regional or metastatic disease, no previous systemic therapy for advanced disease, uni-dimensionally assessed Response Evaluation Criteria in Solid Tumours-defined measurable disease, and an Eastern Cooperative Oncology Group performance status of 0–1. Patients were randomly assigned (1:1) at baseline to a conventional continuation strategy or drug-free interval strategy using a central computer-generated minimisation programme incorporating a random element. Stratification factors were Memorial Sloan Kettering Cancer Center prognostic group risk factor, sex, trial site, age, disease status, tyrosine kinase inhibitor, and previous nephrectomy. All patients received standard dosing schedules of oral sunitinib (50 mg per day) or oral pazopanib (800 mg per day) for 24 weeks before moving into their randomly allocated group. Patients allocated to the drug-free interval strategy group then had a treatment break until disease progression, when treatment was re-instated. Patients in the conventional continuation strategy group continued treatment. Patients, treating clinicians, and the study team were aware of treatment allocation. The co-primary endpoints were overall survival and quality-adjusted life-years (QALYs); non-inferiority was shown if the lower limit of the two-sided 95% CI for the overall survival hazard ratio (HR) was 0·812 or higher and if the lower limit of the two-sided 95% CI of the marginal difference in mean QALYs was –0·156 or higher. The co-primary endpoints were assessed in the intention-to-treat (ITT) population, which included all randomly assigned patients, and the per-protocol population, which excluded patients in the ITT population with major protocol violations and who did not begin their randomisation allocation as per the protocol. Non-inferiority was to be concluded if it was met for both endpoints in both analysis populations. Safety was assessed in all participants who received a tyrosine kinase inhibitor. The trial was registered with ISRCTN, 06473203, and EudraCT, 2011-001098-16. FindingsBetween Jan 13, 2012, and Sept 12, 2017, 2197 patients were screened for eligibility, of whom 920 were randomly assigned to the conventional continuation strategy (n=461) or the drug-free interval strategy (n=459; 668 [73%] male and 251 [27%] female; 885 [96%] White and 23 [3%] non-White). The median follow-up time was 58 months (IQR 46–73 months) in the ITT population and 58 months (46–72) in the per-protocol population. 488 patients continued on the trial after week 24. For overall survival, non-inferiority was demonstrated in the ITT population only (adjusted HR 0·97 [95% CI 0·83 to 1·12] in the ITT population; 0·94 [0·80 to 1·09] in the per-protocol population). Non-inferiority was demonstrated for QALYs in the ITT population (n=919) and per-protocol (n=871) population (marginal effect difference 0·06 [95% CI –0·11 to 0·23] for the ITT population; 0·04 [–0·14 to 0·21] for the per-protocol population). The most common grade 3 or worse adverse events were hypertension (124 [26%] of 485 patients in the conventional continuation strategy group vs 127 [29%] of 431 patients in the drug-free interval strategy group); hepatotoxicity (55 [11%] vs 48 [11%]); and fatigue (39 [8%] vs 63 [15%]). 192 (21%) of 920 participants had a serious adverse reaction. 12 treatment-related deaths were reported (three patients in the conventional continuation strategy group; nine patients in the drug-free interval strategy group) due to vascular (n=3), cardiac (n=3), hepatobiliary (n=3), gastrointestinal (n=1), or nervous system (n=1) disorders, and from infections and infestations (n=1). InterpretationOverall, non-inferiority between groups could not be concluded. However, there seemed to be no clinically meaningful reduction in life expectancy between the drug-free interval strategy and conventional continuation strategy groups and treatment breaks might be a feasible and cost-effective option with lifestyle benefits for patients during tyrosine kinase inhibitor therapy in patients with renal cell carcinoma. FundingUK National Institute for Health and Care Research.

Nanophase of Ga 2 O 3 has potentially important applications in photocatalysis. We report the synthesis of nanophase of the metastable γ- and stable β-Ga 2 O 3 and demonstrate that it is possible to prepare a continuously varying mixture starting from the pure metastable γ- to the pure β-phase. This is achieved by employing a facile and reliable combustion route, using urea as a fuel. Typical grain sizes, as estimated from XRD studies, are about 3 nm. Given the importance of surface chemistry for potential applications, thermogravimetric coupled with mass spectrometry is used in conjunction with FTIR to elucidate the chemistry of the adsorbed surface layer. Studies on the γ-Ga 2 O 3 phase indicate the occurrence of weight loss of 8.1% in multiple steps. Evolved gas analysis and FTIR studies show presence of physisorbed H 2 O molecules and chemisorbed –(OH) ions bonded to active surface states and accounts predominantly for the observed weight loss.

We present Synchrotron XRD measurements on powdered single crystal samples of BaFe2-xRuxAs2 samples, as a function of Ru content at room temperature. The Rietveld refinements reveal that the a-axis increases with Ru substitution, while the c-axis decreases. The variation of positional co-ordinates of As (zAs), the Fe-As bond length and the As-Fe-As bond angles have been determined from the Rietveld refinements. In the sample with x=0.1, temperature dependent XRD measurements were carried out. The results indicate that while the orthorhombicity shows the characteristic increase with decrease in temperature, the As-Fe-As bond angles, Fe-As bond length and positional co-ordinate of the As show definite anomalies close to the structural transition. First principle ab-initio simulations are performed in order to understand the experimentally observed anomalies in structural parameters. The experimental observations are discussed in the context of the simulation results.