ARC Technology (United States)

The paper presents design of a high-level control strategy for an active car seat suspension system based on model predictive control (MPC). The MPC formulation aims to improve ride comfort by minimizing vertical seat acceleration amplitudes, while explicitly enforcing physical constraints on the suspension stroke and actuator force. Simulation results gained through a linear half-car model demonstrate that the proposed MPC strategy significantly outperforms a baseline linear quadratic regulator (LQR), primarily due to its ability to directly account for the hardware constraints. Robustness of the proposed approach is illustrated through control system evaluation based on a more realistic and complex nonlinear seat mechanism model, including actuator dynamics and friction. When combined with a proper low-level controller, the overall system achieves performance close to that of the idealized linear system, highlighting the potential for real-world application.

Characterization of battery cells and the creation of measurement-based models is a key step in the design process of battery packs for electric vehicles (EVs). Simulations of such models allow optimization of a battery pack design to minimize safety and functional errors that might appear late in the design stage and increase development time and cost. This paper demonstrates a method for measuring battery cell impedance with a vector network analyzer (VNA) under switch-controlled pulsed charge and discharge bias current and presents the resulting impact on the inductance of the cell at 108 MHz. The battery cell inductance under bias current at temperatures from -20°C to 40°C is presented. Finally, the bias current and temperature impact on the battery cell are shown.

Characterization of cells is a key step in the design process of battery packs. Measurement-based models allow simulations of battery packs and electric vehicles in the early design stage reducing development time and cost. This paper demonstrates a method for measuring battery cell impedance with higher precision and wider bandwidth using vector network analyzer in the frequency range from 1 MHz to 680 MHz. A printed circuit board (PCB) adapter is developed to connect the battery cell to coaxial cables and allow for repeatable results. Inductance dependence on state of charge and inductance dependence on axial position of the probe are presented. Proposals for further improvements are given.

Batteries raise issues in electric vehicles because of their limited range and lifespan. They can however be extended by implementing smart, accurate and computationally inexpensive control algorithms. Herein, a lithium-ion battery cell is modelled with an equivalent circuit model which is complex enough to track the output voltage of the cell while remaining simple enough to be used in a control algorithm. This work presents the identification procedure of equivalent circuit model parameters for a lithium-ion battery cell by applying high currents to the cell. Consequently, high accuracy was achieved for the whole range of possible currents. The parameters were identified on a dataset with high currents, while the model was evaluated on a different dataset acquired from a real electric vehicle usage data. Metrics from both the identification and the validation datasets are similar meaning that the model generalises well.

Quantum Applications In article number 2201064, Ajit K. Roy and co-workers present a perspective of quantum technology state of the art wherein critical stumbling blocks for quantum technology development are identified. As represented in the cover, atomic defects are created in a transition metal chalcogenide (TMD) thin film with a specialized tip in an atomic force microscope. AFM tip tracing indicates atomic-scale localization of materials states at the defect location. These controlled and localized defect sites are the source of quantum signal generation under a biased field.

View Video Presentation: https://doi.org/10.2514/6.2021-1370.vid Nanosecond-pulsed high-frequency discharges (NPHFD) have proven to be effective in igniting fuel-air mixtures under lean conditions in both quiescent and flowing environments. However, limited research has been conducted comparing the kernel growth behavior of a long duration conventional discharge to a long train of discharges produced by an NPHFD ignition system. Therefore, this work looks to conduct a comparison between a single capacitive discharge and multiple nanosecond discharges under the conditions of a 5 m/s flow and an equivalence ratio of 0.60. The total time of energy deposition and average power was approximately matched between the ignition systems and three total energy deposition times were tested: 0.05, 0.25, and 0.50 ms. Each of these conditions were tested at electrode gap distances of 1.00 and 2.00 mm. The effect different power loadings have on kernel growth and elongation were analyzed using infrared imaging in tandem with a kernel tracking program that utilizes Prewitt edge detection to identify the kernel area. Results for the 1.00 mm gap condition showed that matching the average power while varying the total discharge time resulted in similar trends in kernel area growth between the two systems. In the case of the 2.00 mm gap condition, conducting the same analysis resulted in the kernel areas for the NPHFD system to differ by more than 15% from those of the conventional system at every total time condition. Additionally, it was found that increasing the gap distance increased the kernel area of the NPHFD system from 26 – 54% where it only increased the kernel area of the conventional system by 9 – 10% depending on the total time condition. Therefore, the NPHFD system was found to benefit more from the increased gap distance than the conventional system.

Advanced Imaging Technology (AIT) uses millimeter-waves for airport passenger screening. The Identification of Explosives (IDX) technique addresses secondary screening of detected anomalies by analyzing the reflectivity data across the frequency band of the imaging system to probe the electrical permittivity of the potential threat. To be practical, IDX must apply to targets that are not configured for free-space metrology, but have poorly defined surfaces and are imaged with non-ideal boundaries. In particular, the magnitude of the reflection coefficient, which is key to free-space measurement, cannot be obtained with any confidence. The detection is accomplished from frequency-dependent features in the interference spectrum, which provide material identifying information in the form of the dielectric loss tangent.

Fatigue tests were carried out at the stress ratio R = -1 using a 20 kHz ultrasonic testing facility to investigate the effects of low temperature nitriding on the fatigue properties of Ti-6Al-4V alloy in the very high cycle fatigue (VHCF) regime in detail. The oscillation and fatigue behavior of the nitrided Ti-alloy were characterized by measuring parameters like the ultrasonic generator power, the displacement of the specimens and dissipated energy under ultrasonic cyclic load. Moreover, the surface microstructure of the nitrided Ti-alloy was characterized using a micro-Vickers hardness tester, an optical microscope, scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron backscatter diffraction technique (EBSD) to clarify the fatigue fracture mechanism. The Ti-alloy nitrided at the temperature of 873 K showed duplex S-N properties consisting of the respective fracture modes of the surface fracture and the subsurface fracture. The low temperature nitriding reduced the surface fatigue life of Ti-alloy in comparison to the un-nitrided one due to the formation of a brittle titanium nitride (Ti2N), whereas the subsurface fatigue life in the VHCF regime was increased by the low temperature nitriding. In addition, the fatigue fracture mechanisms of the low temperature nitrided Ti-alloy were discussed from viewpoints of fractography and fracture mechanics.