ONR and NAVY Research in Ceramic Matrix composites systems for advanced naval engines

Ceramic matrix composites (CMCs) are strategic propulsion materials due to their potentials to meet operational capability and requirements for advanced Naval engine systems. However, as in any new material systems, CMCs present technological issues and concerns when it comes to transition and maturation for advanced engine applications. These issues, all related to aggressive Naval engine operational environments, needs to be explored and taken into account in the design and integration of CMC hot-section materials and components for enhanced reliability and durability. Current focused S&T efforts will be presented and discussed as to how they are strategized to meet the Navy-unique challenges in conjunction with transitioning of CMC material systems to advanced Naval engines

Quantum cohomology determined with negative structure constants present

Let \mbox{IG}:=\mbox{IG}(2,2n+1) denote the odd symplectic Grassmannian of lines which is a horospherical variety of Picard rank 1. The quantum cohomology ring \mbox{QH}^*(\mbox{IG}) has negative structure constants. For $n \geq 3$, we give a positivity condition that implies the quantum cohomology ring \mbox{QH}^*(\mbox{IG}) is the only quantum deformation of the cohomology ring \mbox{H}^*(\mbox{IG}) up to the scaling of the quantum parameter. This is a modification of a conjecture by Fulton

Navy research for materials beyond Ni- Superalloys

Creation and development of high temperature materials is critical to many processes and applications important to DoD. The dramatic growth of computational modeling programs and 2D and 3D characterization tools that can examine atomistic features to the continuum scales has had a big impact on this materials research and holds promise in creating new materials and/or new or more efficient materials processing pathways. Propulsion materials for both Naval aircraft and ship gas turbine engines are subjected to the corrosive environment of the sea to differing degrees. All potential materials tend to become unstable in many high temperatures environments, particularly in the salt-laden marine environment, without the presence of a stable, protective coating on the component surface. Materials life is dependent on dynamic combinations of many inherent factors such as temperature, environment, and stress and need to be to be resistant to oxidation, corrosion, or alternating cycles of oxidation and corrosion. Research seeks to explore and understand the thermodynamics and kinetics of materials interactions and materials stability in Naval environments and temperatures in order to develop models that lead to creating new materials or establishing life prediction capabilities for existing and novel materials. Materials capable of high temperatures performance above that possible with nickel-based superalloys (~1100°C) will play a key role in enabling further advances in gas turbine engine capabilities. Such materials will lead to improvements in engine efficiency, reduced fuel costs, and decreased costs in maintenance and total life cycle. Mo- and Nb-based based intermetallic alloys offer the possibility of higher temperature performance above 1100°C. The Mo-Si-B alloy system has high temperature stability (melting temperature, Tm, is above 2000°C) and attractive materials properties for different combinations of equilibrated phases. Recently a new class of high entropy alloys (HEAs) has received a lot of attention and its design potentially offers opportunities to high temperature strength properties exceeding that of traditional superalloys. The HEA systems contain at least five principle elements, each of which has an atomic percentage between 5 at.% and 35 at.% . It has been reported that HEAs possess other desirable properties, such as high hardness, outstanding wear resistance, good fatigue resistance characteristics, good thermal stability and, in general, good oxidation and corrosion. This paper will address the research needed to advance these alloys for U.S. Naval applications

Acer negundo subsp. latifolium (Pax) Schwerin

https://thekeep.eiu.edu/herbarium_specimens_byname/21710/thumbnail.jp

High-Performance Flexible Quasi-Solid-State Supercapacitors Realized by Molybdenum Dioxide@Nitrogen-Doped Carbon and Copper Cobalt Sulfide Tubular Nanostructures

Flexible quasi‐/all‐solid‐state supercapacitors have elicited scientific attention to fulfill the explosive demand for portable and wearable electronic devices. However, the use of electrode materials faces several challenges, such as intrinsically slow kinetics and volume change upon cycling, which impede the energy output and electrochemical stability. This study presents well‐aligned molybdenum dioxide@nitrogen‐doped carbon (MoO2@NC) and copper cobalt sulfide (CuCo2S4) tubular nanostructures grown on flexible carbon fiber for use as electrode materials in supercapacitors. Benefiting from the chemically stable interfaces, affluent active sites, and efficient 1D electron transport, the MoO2@NC and CuCo2S4 nanostructures integrated on conductive substrates deliver excellent electrochemical performance. A flexible quasi‐solid‐state asymmetric supercapacitor composed of MoO2@NC as the negative electrode and CuCo2S4 as the positive electrode achieves an ultrahigh energy density of 65.1 W h kg−1 at a power density of 800 W kg−1 and retains a favorable energy density of 27.6 W h kg−1 at an ultrahigh power density of 12.8 kW kg−1. Moreover, it demonstrates good cycling performance with 90.6% capacitance retention after 5000 cycles and excellent mechanical flexibility by enabling 92.2% capacitance retention after 2000 bending cycles. This study provides an effective strategy to develop electrode materials with superior electrochemical performance for flexible supercapacitors