Dynamic similarity design method for an aero-engine dualrotor test rig

This paper presents a dynamic similarity design method to design a scale dynamic similarity model (DSM) for a dual-rotor test rig of an aero-engine. Such a test rig is usually used to investigate the major dynamic characteristics of the full-size model (FSM) and to reduce the testing cost and time for experiments on practical aero engine structures. Firstly, the dynamic equivalent model (DEM) of a dual-rotor system is modelled based on its FSM using parametric modelling, and the first 10 frequencies and mode shapes of the DEM are updated to agree with the FSM by modifying the geometrical shapes of the DEM. Then, the scaling laws for the relative parameters (such as geometry sizes of the rotors, stiffness of the supports, inherent properties) between the DEM and its scale DSM were derived from their equations of motion, and the scaling factors of the above-mentioned parameters are determined by the theory of dimensional analyses. After that, the corresponding parameters of the scale DSM of the dual-rotor test rig can be determined by using the scaling factors. In addition, the scale DSM is further updated by considering the coupling effect between the disks and shafts. Finally, critical speed and unbalance response analysis of the FSM and the updated scale DSM are performed to validate the proposed method

Invited; ALD of robust amorphous oxide TFTS with turn on at the Boltzmann limit

The development of amorphous oxide semiconductors have driven great advances in display technology. These materials are poised to expand into new applications by heterointegration at the back-end-of-line (BEOL) of Si CMOS for diverse uses in power harvesting, conversion and management as well as in-memory computing and AI hardware. For acceptance in IC foundries, atomic layer deposition (ALD) is an attractive technology with nanometer-scale precision. Recently, significant advances have been made in ALD processes for both n- and ptype oxide semiconductors [1], [2]. Here, we report robust thin film transistors (TFTs) made using n-type zinc-tinoxide deposited by ALD, with excellent robustness to aging and bias stress. The use of an in situ gate insulator formed by ALD enables a sub-threshold slope (SS) at the Boltzmann limit of 60 mV·dec-1 at room temperature. Please click Download on the upper right corner to see the full abstract

Fluid-Structural Coupling Effects on the Dynamics of Mistuned Bladed Disks

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77177/1/AIAA-23809-593.pd

Continuous manganese delivery via osmotic pumps for manganese-enhanced mouse MRI does not impair spatial learning but leads to skin ulceration

Manganese-enhanced magnetic resonance imaging (MEMRI) is a widely used technique in rodent neuroimaging studies. Traditionally, Mn2+ is delivered to animals via a systemic injection; however, this can lead to toxic effects at high doses. Recent studies have shown that subcutaneously implanted mini-osmotic pumps can be used to continuously deliver manganese chloride (MnCl2), and that they produce satisfactory contrast while circumventing many of the toxic side effects. However, neither the time-course of signal enhancement nor the effect of continuous Mn2+ delivery on behaviour, particularly learning and memory, have been well-characterized. Here, we investigated the effect of MnCl2 dose and route of administration on a) spatial learning in the Morris Water Maze and b) tissue signal enhancement in the mouse brain. Even as early as 3 days after pump implantation, infusion of 25–50 mg/kg/day MnCl2 via osmotic pump produced signal enhancement as good as or better than that achieved 24 h after a single 50 mg/kg intraperitoneal injection. Neither route of delivery nor MnCl2 dose adversely affected spatial learning and memory on the water maze. However, especially at higher doses, mice receiving MnCl2 via osmotic pumps developed skin ulceration which limited the imaging window. With these findings, we provide recommendations for route and dose of MnCl2 to use for different study designs

High‐Performance Zinc Tin Oxide TFTs with Active Layers Deposited by Atomic Layer Deposition

New deposition techniques for amorphous oxide semiconductors compatible with silicon back end of line manufacturing are needed for 3D monolithic integration of thin‐film electronics. Here, three atomic layer deposition (ALD) processes are compared for the fabrication of amorphous zinc tin oxide (ZTO) channels in bottom‐gate, top‐contact n‐channel transistors. As‐deposited ZTO films, made by ALD at 150–200 °C, exhibit semiconducting, enhancement‐mode behavior with electron mobility as high as 13 cm2 V−1 s−1, due to a low density of oxygen‐related defects. ZTO deposited at 200 °C using a hybrid thermal‐plasma ALD process with an optimal tin composition of 21%, post‐annealed at 400 °C, shows excellent performance with a record high mobility of 22.1 cm2 V–1 s–1 and a subthreshold slope of 0.29 V dec–1. Increasing the deposition temperature and performing post‐deposition anneals at 300–500 °C lead to an increased density of the X‐ray amorphous ZTO film, improving its electrical properties. By optimizing the ZTO active layer thickness and using a high‐k gate insulator (ALD Al2O3), the transistor switching voltage is lowered, enabling electrical compatibility with silicon integrated circuits. This work opens the possibility of monolithic integration of ALD ZTO‐based thin‐film electronics with silicon integrated circuits or onto large‐area flexible substrates.Three atomic layer deposition (ALD) processes are investigated for the deposition of zinc tin oxide (ZTO) as the active layer in thin‐film transistors (TFTs). With a low density of oxygen vacancies, as‐deposited films exhibit semiconducting, enhancement‐mode behavior. Post‐deposition anneals result in increased film density and record high electron mobility for ALD ZTO TFTs using process temperatures within the back‐end‐of‐line thermal budget.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156226/3/aelm202000195-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156226/2/aelm202000195.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156226/1/aelm202000195_am.pd

From Expert Discipline to Common Practice: A Vision and Research Agenda for Extending the Reach of Enterprise Modeling

The benefits of enterprise modeling (EM) and its contribution to organizational tasks are largely undisputed in business and information systems engineering. EM as a discipline has been around for several decades but is typically performed by a limited number of people in organizations with an affinity to modeling. What is captured in models is only a fragment of what ought to be captured. Thus, this research note argues that EM is far from its maximum potential. Many people develop some kind of model in their local practice without thinking about it consciously. Exploiting the potential of this “grass roots modeling” could lead to groundbreaking innovations. The aim is to investigate integration of the established practices of modeling with local practices of creating and using model-like artifacts of relevance for the overall organization. The paper develops a vision for extending the reach of EM, identifies research areas contributing to the vision and proposes elements of a future research Agenda