On Policies for Single-leg Revenue Management with Limited Demand Information

In this paper we study the single-item revenue management problem, with no information given about the demand trajectory over time. When the item is sold through accepting/rejecting different fare classes, Ball and Queyranne (2009) have established the tight competitive ratio for this problem using booking limit policies, which raise the acceptance threshold as the remaining inventory dwindles. However, when the item is sold through dynamic pricing instead, there is the additional challenge that offering a low price may entice high-paying customers to substitute down. We show that despite this challenge, the same competitive ratio can still be achieved using a randomized dynamic pricing policy. Our policy incorporates the price-skimming technique from Eren and Maglaras (2010), but importantly we show how the randomized price distribution should be stochastically-increased as the remaining inventory dwindles. A key technical ingredient in our policy is a new "valuation tracking" subroutine, which tracks the possible values for the optimum, and follows the most "inventory-conservative" control which maintains the desired competitive ratio. Finally, we demonstrate the empirical effectiveness of our policy in simulations, where its average-case performance surpasses all naive modifications of the existing policies

Advanced Nanoparticle Coatings for Stabilizing Layered Ni‐Rich Oxide Cathodes in Solid‐State Batteries

Improving the interfacial stability between cathode active material (CAM) and solid electrolyte (SE) is a vital step toward the development of high-performance solid-state batteries (SSBs). One of the challenges plaguing this field is an economical and scalable approach to fabricate high-quality protective coatings on the CAM particles. A new wet-coating strategy based on preformed nanoparticles is presented herein. Nonagglomerated nanoparticles of the coating material (≤5 nm, exemplified for ZrO$_{2}$) are prepared by solvothermal synthesis, and after surface functionalization, applied to a layered Ni-rich oxide CAM, LiNi$_{0.85}$Co$_{0.10}$Mn$_{0.05}$O$_{2}$ (NCM85), producing a uniform surface layer with a unique structure. Remarkably, when used in pelletized SSBs with argyrodite Li$_{6}$PS$_{5}$Cl as SE, the coated NCM85 is found to exhibit superior lithium-storage properties (q$_{dis}$ ≈ 204 mAh g$_{NCM85}$$^{-1}$ at 0.1 C rate and 45 °C) and good rate capability. The key to the observed improvement lies in the homogeneity of coating, suppressing interfacial side reactions while simultaneously limiting gas evolution during operation. Moreover, this strategy is proven to have a similar effect in liquid electrolyte-based Li-ion batteries and can potentially be used for the application of other, even more favorable, nanoparticle coatings

Design-of-experiments-guided optimization of slurry-cast cathodes for solid-state batteries

Laboratory research into bulk-type solid-state batteries (SSBs) has been focused predominantly on powder-based, pelletized cells and has been sufficient to evaluate fundamental limitations and tailor the constituents to some degree. However, to improve experimental reliability and for commercial implementation of this technology, competitive slurry-cast electrodes are required. Here, we report on the application of an approach guided by design of experiments (DoE) to evaluate the influence of the type/content of polymer binder and conductive carbon additive on the cyclability and processability of Li$_{1+x}$(Ni$_{0.6}$Co$_{0.2}$Mn$_{0.2}$)$_{1}$−xO$_{2}$ (NCM622) cathodes in SSB cells using lithium thiophosphate solid electrolytes. The predictions are verified by charge-discharge and impedance spectroscopy measurements. Furthermore, structural changes and gas evolution are monitored via X-ray diffraction and differential electrochemical mass spectrometry, respectively, in an attempt to rationalize and support the DoE results. In summary, the optimized combination of polymer binder and conductive carbon additive leads to high electrochemical performance and good processability

Niobium Incorporation into CsPbI2Br for Stable and Efficient All-Inorganic Perovskite Solar Cells

All-inorganic perovskites are attracting increasing attention due to their superior thermal stability than that of the traditional CH3NH3PbI3, while their inferior phase stability in ambient conditions is still an unsolved issue. Here, for the first time, we report the incorporation of niobium (Nb5+) ions into the CsPbI2Br perovskite. Results indicate that Nb5+ can effectively stabilize the photoactive α-CsPbI2Br phase by the possible substitution of Pb2+. With 0.5% Nb doping, the carbon electrode-based all-inorganic perovskite solar cells achieved a high photoconversion efficiency value of 10.42%, 15% higher than that of the control device. The Nb5+ incorporation reduces the charge recombination in the perovskite, leading to a champion Voc value of 1.27 V and a negligible hysteresis effect. This work explicates the high compatibility of all-inorganic perovskite materials and unlocks the opportunities for the use of high-valence ions for perovskite property modification

The Effect of Single versus Polycrystalline Cathode Particles on All‐Solid‐State Battery Performance

Lithium-thiophosphate-based all-solid-state batteries (ASSBs) are increasingly attracting attention for high-density electrochemical energy storage. In this work, the cycling performance of single and polycrystalline forms of LiNi$_{x}$Co$_{y}$Mn$_{z}$O$_{2}$ (NCM, with ≥83% Ni content) cathode active materials in ASSB cells with an Li$_{4}$Ti$_{5}$O$_{12}$ composite anode is explored, and the advantages and disadvantages of both morphologies are discussed. The virtual lack of grain boundaries in the quasi-single-crystalline material is found to contribute to improved stability by eliminating the tendency of Ni-rich NCM particles to crack during cycling, due to volume differences between the lithiated and delithiated phases. Although the higher crack resistance mitigates effects of chemical oxidation of the lithium thiophosphate solid electrolyte, the cells suffer from electrochemical side reactions occurring at the cathode interfaces. However, coating the single-crystal particles with a protective LiNbO$_{3}$ overlayer helps to stabilize the interface between cathode active material and solid electrolyte, leading to a capacity retention of 93% after 200 cycles (with q$_{dis}$ ≈ 160 mAh g$_{NCM}$$^{-1}$ or 1.7 mAh cm$^{-2}$ at C/5 rate and 45 °C). Overall, this work highlights the importance of addressing electro-chemo-mechanical phenomena in ASSB electrodes

The influence of maternal and infant nutrition on cardiometabolic traits: novel findings and future research directions from four Canadian birth cohort studies

A mother's nutritional choices while pregnant may have a great influence on her baby's development in the womb and during infancy. There is evidence that what a mother eats during pregnancy interacts with her genes to affect her child's susceptibility to poor health outcomes including childhood obesity, pre-diabetes, allergy and asthma. Furthermore, after what an infant eats can change his or her intestinal bacteria, which can further influence the development of these poor outcomes. In the present paper, we review the importance of birth cohorts, the formation and early findings from a multi-ethnic birth cohort alliance in Canada and summarise our future research directions for this birth cohort alliance. We summarise a method for harmonising collection and analysis of self-reported dietary data across multiple cohorts and provide examples of how this birth cohort alliance has contributed to our understanding of gestational diabetes risk; ethnic and diet-influences differences in the healthy infant microbiome; and the interplay between diet, ethnicity and birth weight. Ongoing work in this birth cohort alliance will focus on the use of metabolomic profiling to measure dietary intake, discovery of unique diet–gene and diet–epigenome interactions, and qualitative interviews with families of children at risk of metabolic syndrome. Our findings to-date and future areas of research will advance the evidence base that informs dietary guidelines in pregnancy, infancy and childhood, and will be relevant to diverse and high-risk populations of Canada and other high-income countries