State Library of Ohio

Many regions of heterochromatin associate with the nuclear periphery and are known as Lamin-associated domains (LADs). Histone acetyltransferase 1 (Hat1) is a highly conserved enzyme which acetylates newly synthesized histones H4 on lysines 5 and 12 prior to their deposition on chromatin. Hat1 is required to preserve chromatin accessibility within a subset of LADs called Hat1-dependent accessibility domains (HADs). Here we profile a diverse set of histone modifications in Hat1 KO and WT immortalized mouse embryonic fibroblasts (iMEFs) and find that Hat1 regulates diverse aspects of the structure of HADs and non-HAD LADs (nhLADS). In HADs, these changes include the conversion of H3K9me2 to H3K9me3. Analysis of H3K9-specific histone methyltransferases (HMTs) shows that that Suv39h1 and Suv39h2 have distinct localization patterns, where only Suv39h2 localizes to LADs. G9a only localizes to LADs in regions enriched for H3K9me2. We find that Hat1 loss results in a redistribution of these HMTs in both HADs and nh LADs. There is a decrease in the levels of G9a with a concomitant increase in Suv39h2. These results suggest Hat1 functions to restrain the formation of a more strongly heterochromatic state and highlight a role for Hat1 as an essential regulator of heterochromatin inheritance.

Abstract The design of complex structural components in the automotive industry is an evolving process where one change in design aspect can have cascading effects on the manufacturability of the design. Traditionally, design and manufacturing are treated separately in a sequential design process, which leads to time and cost inefficiencies. This paper introduces a data-driven benefit-cost analysis (BCA) framework that incorporates design for manufacturing (DfM) principles. By quantitatively evaluating the trade-offs between the competing design and manufacturing objectives and integrating them in BCA, the framework simultaneously assesses design parameters and manufacturability metrics to obtain optimal designs. Qualitative metrics are introduced as weights to improve the efficiency of the framework. The presented methodology is applied to an extensive dataset of car hood inner panels, i.e., hood frames (CarHoods 10k) that comprise nearly 10,000 parametrized design variants. Normalization techniques are used to quantify design performance RD, and manufacturability objectives RM into a unified rating system that constructs the basis for a point-based design improvement strategy. Therefore, design alternatives are explored in an active evaluation system. Results demonstrate that considering manufacturing early in the design process reduces design iterations and motivates one to make more rational decisions for design improvements. The presented data-driven decision-making can be potentially extended to other structural components by applying the same principles.

We predict the sensitivity of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) to faint, resolved Milky Way satellite galaxies and outer-halo star clusters. We characterize the expected sensitivity using simulated LSST data from the LSST Dark Energy Science Collaboration (DESC) Data Challenge 2 (DC2) accessed and analyzed with the Rubin Science Platform as part of the Rubin Early Science Program. We simulate resolved stellar populations of Milky Way satellite galaxies and outer-halo star clusters over a wide range of sizes, luminosities, and heliocentric distances, which are broadly consistent with expectations for the Milky Way satellite system. We inject simulated stars into the DC2 catalog with realistic photometric uncertainties and star/galaxy separation derived from the DC2 data itself. We assess the probability that each simulated system would be detected by LSST using a conventional isochrone matched-filter technique. We find that assuming perfect star/galaxy separation enables the detection of resolved stellar systems with MV = 0 mag and r1/2 = 10 pc with >50% efficiency out to a heliocentric distance of ~250 kpc. Similar detection efficiency is possible with a simple star/galaxy separation criterion based on measured quantities, although the false positive rate is higher due to leakage of background galaxies into the stellar sample. When assuming perfect star/galaxy classification and a model for the galaxy-halo connection fit to current data, we predict that 89 +/- 20 Milky Way satellite galaxies will be detectable with a simple matched-filter algorithm applied to the LSST wide-fast-deep data set. Different assumptions about the performance of star/galaxy classification efficiency can decrease this estimate by ~7-25%, which emphasizes the importance of high-quality star/galaxy separation for studies of the Milky Way satellite population with LSST.

Abstract A new deposition cooling facility was designed and constructed to examine the time-evolution of dust deposition and its effect on the cooling effectiveness of internal cooling circuits typical of gas turbine hot sections. The facility utilizes representative gas turbine engine cooling geometries and operates at relevant coolant and hot gas flow temperatures (650K and 1300K respectively). A combustion chamber is used to create a high speed (180m/s) 2cm diameter jet that impinges at a 26° angle (from the horizontal) onto a pre-oxidized flat plate made from a nickel-based alloy. The backside of this plate is cooled by an array of 0.5mm diameter impingement cooling jets with a 1.03 pressure ratio relative to the hot jet discharge pressure. An infrared camera is used to record the surface temperature of the flat plate as airborne dust is delivered through the cooling circuit. The dust delivered to the test article is 0–5micron Arizona Road Dust. Deposit evolution and cooling effectiveness trends were observed by performing successive tests with varying dust delivery period while maintaining constant dust loading (concentration). Observable patterns in the deposit behavior corroborate quantitative measurements of changes in local cooling effectiveness as measured by the IR camera. A limited test series at lower coolant and jet temperatures highlights the role of temperature in the deposition process.

Abstract Previous experiments demonstrated the effectiveness of using fluidic actuators to throttle the core mass flow through a nozzle guide vane passage. This enables a variable area turbine (VAT) without mechanically moving vanes. The most promising of the fluidic actuators tested was a slot on the suction side of the nozzle guide vane. Using a simple model as a guide, a two-dimensional, RANS, CFD Design of Experiments (DOE) was completed to evaluate the predicted mass flow rate reduction, effectiveness, pressure loss, and exit flow angle for various slot geometries. This DOE was succeeded by the experimental evaluation of seven candidate slot geometries in a small-scale, single nozzle guide vane passage. These candidate slots span the geometric parameters previously described. Experiments showed that when the injection pressure matches the upstream pressure, increasing slot width from 6% to 19% of the geometric throat caused the percentage of primary flow blocked to go from 6.4% to 24.8%. When the slot was pitched from 0° to 60° into the oncoming flow the percentage of primary flow blocked went from 16.0% to 18.2%. Finally, when the slot location was moved away from the computationally determined optimal location the primary flow blocked was reduced. All slot geometries tested had promising effectiveness, generally blocking around twice as much mass flow as they were injecting. Additionally, total pressure loss was seen to strongly correlate with the amount of flow blocked no matter the slot geometry. The trends seen in the simple model and CFD did match the experiments, however CFD appears to have overestimated the performance of the best slot designs.

Abstract This document presents the results comparing fatigue life and damping performance of an i-DAMP designed blade to a baseline blade. The i-DAMP Method is a design tool that strategically places powder-filled voids in parts that act as a vibration suppression mechanism. The blades in this study are made from Nickel Alloy 718 powder with the Laser Powder Bed Fusion (LPBF) Additive Manufacturing (AM) process. This study is important because of high gas turbine engine maintenance, repair, and overhaul (MRO) costs and the potential of AM to solve integrity and repeatability issues for future components. The i-DAMP method, which is a design approach for achieving vibration suppression that promotes lightweight and low stress parts, is a viable solution to the AM integrity issues. The damping comparisons in this study show that the i-DAMP designed blades achieve 45–60% vibration suppression over the baseline blades. The study also shows that a 10X fatigue life resistance is achieved by the i-DAMP designed blade versus the baseline blade. The damping and fatigue performance improvement in the i-DAMP design blades compared to baseline is a necessary step before advancing the study to i-DAMP blade assessments on bladed disks (blisks) operating in a spin rig environment.

Abstract Aviation sustainability is a significant consideration in the designs of future generation aircraft. One way to achieve aviation sustainability is by reducing the overall drag acting on the aircraft. One approach being researched to achieve this goal is the implementation of boundary layer ingesting (BLI) technique. BLI technique has been shown by many researchers around the globe to be able to significantly improve the overall aircraft performance by reducing the drag and noise generated by the aircraft. However, inlets designed to ingest boundary layers tend to develop a large region of low-pressure flow which can drastically harm the overall performance of an engine placed behind the distorted flow. The success of BLI techniques heavily depends on the design of an engine fan that can deliver high aerodynamic performance even under the influence of the distorted inlet flow. The study of this paper outlines a procedure to achieve this goal by utilizing CFD-based design optimization methods. The study was broken up into three primary phases which iterated the design of an initial baseline geometry with the primary objective function being the adiabatic efficiency of the fan. The results of this study show that the optimized fans can improve the adiabatic efficiency by around 4–5% when compared to the baseline design.

Abstract A versatile procedure is presented for simulating the growth and thermal impact of deposition in representative gas turbine cooling circuits. The methodology comprises the following sequence: (1) employ CFD to obtain a steady flow solution, (2) predict particle impacts and deposits with the temperature sensitive Ohio State University (OSU) deposition model, and (3) implement conjugate mesh-morphing of both the fluid and solid domains to simulate the evolution of deposit structures. Impinging jet experiments are conducted at 990K with aerosolized Arizona Road Dust (ARD 0–10μm) impacting an unheated target. The simulations are shown to accurately model the deposit cone evolution. A ‘regridding’ step is employed in the mesh-morphing routine to significantly improve the simulation’s stability during adaptation of the mesh. Subsequent tests are conducted in an effusion cooling deposition facility (ECDF), where an effusion plate is heated to 1144K with cooling air supplied at varying temperatures (811–978K) at a constant backflow margin of 3%. ARD (0–10 μm) is injected and the reduction in cooling air mass flow is monitored. The results illustrate that higher cooling air temperatures lead to a quicker reduction in cooling air mass flow as well as variations in the deposit structure within the effusion holes. The enhanced mesh-morphing routine is integrated with the temperature sensitive OSU deposition model to simulate these tests. The simulations capture the increasing blockage rate with temperature and display similarities in the deposit structures. The ‘regridding’ step is determined to play a critical role in ensuring stability of the mesh-morphing routine in an effusion geometry. Additionally, the simulations provide insight into the initial formation and successive evolution of effusion hole deposits and the effect this has on cooling film effectiveness.

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