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1. Novel Design of Six-Phase Spoke-Type Ferrite Permanent Magnet Motor for Electric Truck Application

   https://doi.org/10.3390/en15061997  

   Won, Hoyun ; Hong, Yang-Ki ; Choi, Minyeong ; Platt, Jonathan ; Bryant, Briana ; Choi, Seungdeog ; Li, Shuhui ; Yoon, Hwan-Sik ; Haskew, Timothy A. ; Lee, Jongkook ; et al ( March 2022 , Energies)

   This paper proposes a 300 kW 24-slot/10-pole 6-phase stator-shifted fractional-slot concentrated winding spoke-type ferrite permanent magnet machine for electric truck applications. The proposed motor consists of a stator with dual three-phase windings positioned 75 degrees apart to reduce higher-order MMF harmonic order, and a rotor with an inexpensive and high-resistance ferrite permanent magnet in the spoke configuration. The simulated result of the stator-shifted machine is compared with a fabricated stator-shifted machine, and the results show good agreement with each other. To further reduce the torque ripple from 2.5 to 0.9% while maintaining a high maximum torque of 2980 Nm, circular voids with a diameter of 11 mm are embedded in the rotor. The proposed motor is evaluated for irreversible demagnetization, mechanical and thermal stability, and fault tolerant ability. To assess the proposed motor performance, the electric truck simulation model is constructed using MATLAB/Simulink and used to compare with the reported 12-slot/10-pole rare-earth permanent magnet-based machine. Compared to a previously reported six-phase rare-earth permanent magnet based flat-type machine, the proposed motor can save 4.3 kWh of energy with a USD 2512 lower cost while retaining a similar motor performance. 

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2. A Truncated Fourier Based Analytical Model for SRMs with Higher Number of Rotor Poles

   https://doi.org/10.1109/ITEC48692.2020.9161708  

   Jin, Zichao ; Jia, Yijiang ; Salameh, Mohamad ; Bilgin, Berker ; Li, Shuwang ; Krishnamurthy, Mahesh ( June 2020 , 2020 IEEE Transportation Electrification Conference & Expo (ITEC))

   Switched reluctance motors (SRM) have been seen as a potential candidate for automotive, aerospace as well as domestic applications and High-Rotor pole SRM (HR-SRM) present a significant advancement in this area. This machine configuration offers most of the the benefits offered by conventional SRMs and has shown significant benefits in efficiency and torque quality. However, HR-SRM has a narrower inductance profile with a lower saliency ratio as compared to a conventional SRM with an identical stator. This can make it inherently challenging to directly adopt mathematical models and sensorless control approaches currently in use. This paper presents a time-efficient analytical model for the characterization of a 6/10 SRM using an inductance model utilizing truncated Fourier series as well as multi-order polynomial curve-fitting algorithm. The inductance model is extended to accurately predict back-EMF and electromagnetic torque response towards obtaining a comprehensive model for every operating point of the machine during dynamic operation. The effectiveness of the proposed concept has analyzed for a prototype machine and verified using Finite Element Analysis (FEA). 

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3. Parallel Unsteady Reynolds-Averaged Navier-Stokes (URANS) Studies of the Performance of ONR Waterjet AxWJ-2

   Stephen E. Monroe ( March 2023 , AIAA Region I Conference, March 2023)

   The accuracy of SimericsMP+ Unsteady Reynolds-Averaged Navier-Stokes (URANS) model is validated by studying turbulent flow past counter-rotating propellers (CRPs). Subsequently, URANS is used to study the axial flow in an Office of Naval Research (ONR) waterjet and its performance. Specifically, experimental data from Miller (1976) is employed for comparison against the URANS results. Due to the large number of degrees of freedom for both simulations, parallel computing over 80 cores is involved. For the CRP study, torque and thrust coefficients are plotted against a range of advance ratios, ensuring a Reynolds number of less than 500,000. For the waterjet, torque and head coefficients are plotted for a range of flow rates at a Reynolds number of 1.25 × 106. For both studies, two different mesh resolutions are utilized. The finer meshes of both studies contained roughly four times the total number of cells found in their respective coarse meshes. These refinements lead to minor improvements, showing good convergence. The URANS torque and thrust coefficients are found to be within 10% of that from experimental data across all advance ratios for the CRP set, showing good agreement. The torque and head coefficients for the waterjet displayed even better agreement, with the greatest error across all flow conditions remaining under 3%. It is concluded that the stator is responsible for 20% of the waterjets power production. 

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4. F1FO ATP synthase molecular motor mechanisms

   https://doi.org/10.3389/fmicb.2022.965620  

   Frasch, Wayne D. ; Bukhari, Zain A. ; Yanagisawa, Seiga ( August 2022 , Frontiers in Microbiology)

   The F-ATP synthase, consisting of F 1 and F O motors connected by a central rotor and the stators, is the enzyme responsible for synthesizing the majority of ATP in all organisms. The F 1 (αβ) 3 ring stator contains three catalytic sites. Single-molecule F 1 rotation studies revealed that ATP hydrolysis at each catalytic site (0°) precedes a power-stroke that rotates subunit-γ 120° with angular velocities that vary with rotational position. Catalytic site conformations vary relative to subunit-γ position (β E , empty; β D , ADP bound; β T , ATP-bound). During a power stroke, β E binds ATP (0°–60°) and β D releases ADP (60°–120°). Årrhenius analysis of the power stroke revealed that elastic energy powers rotation via unwinding the γ-subunit coiled-coil. Energy from ATP binding at 34° closes β E upon subunit-γ to drive rotation to 120° and forcing the subunit-γ to exchange its tether from β E to β D , which changes catalytic site conformations. In F 1 F O , the membrane-bound F O complex contains a ring of c-subunits that is attached to subunit-γ. This c-ring rotates relative to the subunit-a stator in response to transmembrane proton flow driven by a pH gradient, which drives subunit-γ rotation in the opposite direction to force ATP synthesis in F 1 . Single-molecule studies of F 1 F O embedded in lipid bilayer nanodisks showed that the c-ring transiently stopped F 1 -ATPase-driven rotation every 36° (at each c-subunit in the c 10 -ring of E. coli F 1 F O ) and was able to rotate 11° in the direction of ATP synthesis. Protonation and deprotonation of the conserved carboxyl group on each c-subunit is facilitated by separate groups of subunit-a residues, which were determined to have different pKa’s. Mutations of any of any residue from either group changed both pKa values, which changed the occurrence of the 11° rotation proportionately. This supports a Grotthuss mechanism for proton translocation and indicates that proton translocation occurs during the 11° steps. This is consistent with a mechanism in which each 36° of rotation the c-ring during ATP synthesis involves a proton translocation-dependent 11° rotation of the c-ring, followed by a 25° rotation driven by electrostatic interaction of the negatively charged unprotonated carboxyl group to the positively charged essential arginine in subunit-a. 

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5. Power Estimation of an Experimental Ocean Current Turbine Based on the Conformal Mapping and Blade Element Momentum Theory

   https://doi.org/10.1115/IMECE2021-71751  

   Sadeqi, S. ; Xiros, N. ; Aktosun, E. ; VanZwieten, J. ; Sultan, C. ; Ioup, J. ; Rouhi, S. ( November 2021 , ASME International Mechanical Engineering Congress and Exposition (IMECE))

   Conformal mapping techniques have been used in many applications in the two-dimensional environments of engineering and physics, especially in the two-dimensional incompressible flow field that was introduced by Prandtl and Tietjens. These methods show reasonable results in the case of comprehensive analysis of the local coefficients of complex airfoils. The mathematical form of conformal mapping always locally preserves angles of the complex functions but it may change the length of the complex model. This research is based on the design of turbine blades as hydrofoils divided into different individual hydrofoils with decreasing thickness from root to tip. The geometric shapes of these hydrofoils come from the original FX77W121 airfoil shape and from interpolating between the FX77W121, FX77W153, and FX77W258 airfoil shapes. The last three digits of this airfoil family approximate the thickness ratio times 1000 (FX77153 => 15.3 % thickness ratio). Of the different airfoil shapes specified for the optimal rotor, there are 23 unique shapes.[15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 28] This study describes the advantage of using at least one complex variable technique of transformation conformal mapping in two dimensions.

   Conformal mapping techniques are used to form a database for sectional lift and drag coefficients based on turbine blade design to be used in Blade Element Momentum (BEM) theory to predict the performance of a three bladed single rotor horizontal axis ocean current turbine (1.6-meter diameter) by considering the characteristics of the sea-water. In addition, by considering the fact that in the real ocean, the underwater ocean current turbines encounter different velocities, the maximum brake power will be investigated for different incoming current velocities. The conformal mapping technique is used to calculate the local lift coefficients of different hydrofoils with respect to different angles of attack: −180 ≤ AOA ≤ +180. These results will be compared to those from other methods obtained recently by our research group. This method considers the potential flow analysis module that follows a higher-order panel method based on the geometric properties of each hydrofoil cross section. The velocity and pressure fields are obtained directly by the applications of Bernoulli’s principle, then the lift coefficients are calculated from the results of the integration of the pressure field along the hydrofoil surface for any angle of attack. Ultimately, the results of this research will be used for further investigation of the design and construction of a small-scale experimental ocean current turbine to be tested in the towing tank at the University of New Orleans.

    

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