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1. Superior Differential Ion Mobility Spectrometry of Pendular Macromolecules Using Low-Frequency Rectangular Waveforms

   https://doi.org/10.1021/acs.analchem.4c06841  

   Thurman, Hayden A; Gusachenko, Egor; Anderson, Gordon A; Shvartsburg, Alexandre A (April 2025, Analytical Chemistry)

   Ion mobility spectrometry (IMS) can delineate gas-phase ions and probe their geometries. Coupling with electrospray ionization and MS has brought IMS to structural biology, revealing the macromolecular folding and subunit connectivity. However, the orientational averaging of ion–molecule collision cross sections (Ω) in the linear and field asymmetric waveform IMS (FAIMS) diminishes the resolution and structural specificity. In the novel low-field differential (LOD) IMS, a field too weak for ion heating (and thus FAIMS) aligns strong macrodipoles, capturing their magnitudes and directional Ω across the dipole (Ω⊥). However, the bisinusoidal waveforms (from FAIMS) have compromised the resolution, measurement accuracy, and correlation to the ion properties. Large ions amenable to LODIMS have low mobility and diffuse slowly, allowing the waveform frequencies down to ∼10 kHz. The low field and frequency permit generating the ideal rectangular waveforms with a flexible frequency and duty cycle by direct switching (impractical for FAIMS) in a miniature low-power format. This new IMS stage is evaluated for the exemplary large protein albumin (66 kDa) previously studied using the bisinusoidal waveform. The flat voltages and greater form factor initiate the differential IMS effect at lower fields, expand the separation space, and enable the quantification of Ω⊥ values by varying the duty cycle. 

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2. DC Dielectric Strength Evaluation of Motor Winding Insulation for Aerospace Applications

   https://doi.org/10.1109/SDEMPED53223.2025.11154356  

   Arafat, Easir; Islam, Farzana; Ghassemi, Mona (August 2025, IEEE)

   Insulation in electric machines is vital in determining system reliability and lifespan, especially under extreme environmental conditions. With the rapid shift toward More Electric Aircraft (MEA), All Electric Aircraft (AEA), and advanced space missions, electric motor components must perform reliably under low pressures, wide temperature ranges, and exposure to radiation. Magnet wires are central to motor operation, and their insulation must withstand high voltage stress in these demanding conditions. While prior research has predominantly focused on insulation performance under AC or pulse width modulated (PWM) waveforms and partial discharge (PD) behavior, there is a limited understanding of dielectric strength under direct current (DC) stress, particularly at reduced atmospheric pressures. This paper presents an experimental investigation into the DC dielectric strength of three magnet wire types (15 AWG, 18 AWG, and 20 AWG) tested at three pressure levels: 101kPa,80kPa, and 40 kPa. Using a voltage to breakdown with a constant ramp method, the study evaluates the insulation's withstand capacity across wire sizes and environmental pressures. 

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3. Decreasing the Miss Rate and Eliminating the Performance Penalty of a Data Filter Cache

   https://doi.org/10.1145/3449043  

   Stokes, Michael; Whalley, David; Onder, Soner (June 2021, ACM Transactions on Architecture and Code Optimization)

   null (Ed.)

   While data filter caches (DFCs) have been shown to be effective at reducing data access energy, they have not been adopted in processors due to the associated performance penalty caused by high DFC miss rates. In this article, we present a design that both decreases the DFC miss rate and completely eliminates the DFC performance penalty even for a level-one data cache (L1 DC) with a single cycle access time. First, we show that a DFC that lazily fills each word in a DFC line from an L1 DC only when the word is referenced is more energy-efficient than eagerly filling the entire DFC line. For a 512B DFC, we are able to eliminate loads of words into the DFC that are never referenced before being evicted, which occurred for about 75% of the words in 32B lines. Second, we demonstrate that a lazily word filled DFC line can effectively share and pack data words from multiple L1 DC lines to lower the DFC miss rate. For a 512B DFC, we completely avoid accessing the L1 DC for loads about 23% of the time and avoid a fully associative L1 DC access for loads 50% of the time, where the DFC only requires about 2.5% of the size of the L1 DC. Finally, we present a method that completely eliminates the DFC performance penalty by speculatively performing DFC tag checks early and only accessing DFC data when a hit is guaranteed. For a 512B DFC, we improve data access energy usage for the DTLB and L1 DC by 33% with no performance degradation. 

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4. Decreasing the Miss Rate and Eliminating the Performance Penalty of a Data Filter Cache

   https://doi.org/3449043  

   Stokes, Michael; Whalley, David; Onder, Soner (June 2021, ACM transactions on architecture and code optimization)

   Kaeli, David (Ed.)

   While data filter caches (DFCs) have been shown to be effective at reducing data access energy, they have not been adopted in processors due to the associated performance penalty caused by high DFC miss rates. In this article, we present a design that both decreases the DFC miss rate and completely eliminates the DFC performance penalty even for a level-one data cache (L1 DC) with a single cycle access time. First, we show that a DFC that lazily fills each word in a DFC line from an L1 DC only when the word is referenced is more energy-efficient than eagerly filling the entire DFC line. For a 512B DFC, we are able to eliminate loads of words into the DFC that are never referenced before being evicted, which occurred for about 75% of the words in 32B lines. Second, we demonstrate that a lazily word filled DFC line can effectively share and pack data words from multiple L1 DC lines to lower the DFC miss rate. For a 512B DFC, we completely avoid accessing the L1 DC for loads about 23% of the time and avoid a fully associative L1 DC access for loads 50% of the time, where the DFC only requires about 2.5% of the size of the L1 DC. Finally, we present a method that completely eliminates the DFC performance penalty by speculatively performing DFC tag checks early and only accessing DFC data when a hit is guaranteed. For a 512B DFC, we improve data access energy usage for the DTLB and L1 DC by 33% with no performance degradation. 

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5. The Van Allen Probes Electric Field and Waves Instrument: Science Results, Measurements, and Access to Data

   https://doi.org/10.1007/s11214-022-00934-y  

   Breneman, A. W.; Wygant, J. R.; Tian, S.; Cattell, C. A.; Thaller, S. A.; Goetz, K.; Tyler, E.; Colpitts, C.; Dai, L.; Kersten, K.; et al (December 2022, Space Science Reviews)

   Abstract The Van Allen Probes Electric Fields and Waves (EFW) instrument provided measurements of electric fields and spacecraft floating potentials over a wide dynamic range from DC to 6.5 kHz near the equatorial plane of the inner magnetosphere between 600 km altitude and 5.8 Re geocentric distance from October 2012 to November 2019. The two identical instruments provided data to investigate the quasi-static and low frequency fields that drive large-scale convection, waves induced by interplanetary shock impacts that result in rapid relativistic particle energization, ultra-low frequency (ULF) MHD waves which can drive radial diffusion, and higher frequency wave fields and time domain structures that provide particle pitch angle scattering and energization. In addition, measurements of the spacecraft potential provided a density estimate in cold plasmas ( $$<20~\text{eV}$$ < 20 eV ) from 10 to $$3000~\text{cm}^{-3}$$ 3000 cm − 3 . The EFW instrument provided analog electric field signals to EMFISIS for wave analysis, and it received 3d analog signals from the EMFISIS search coil sensors for inclusion in high time resolution waveform data. The electric fields and potentials were measured by current-biased spherical sensors deployed at the end of four 50 m booms in the spacecraft spin plane (spin period $$\sim11~\text{sec}$$ ∼ 11 sec ) and a pair of stacer booms with a total tip-tip separation of 15 m along the spin axis. Survey waveform measurements at 16 and/or 32 S/sec (with a nominal uncertainty of 0.3 mV/m over the prime mission) were available continuously while burst waveform captures at up to 16,384 S/sec provided high frequency waveforms. This post-mission paper provides the reader with information useful for accessing, understanding and using EFW data. Selected science results are discussed and used to highlight instrument capabilities. Science quantities, data quality and error sources, and analysis routines are documented. 

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