Transfer function measurement for automotive intentional EMI and thermal runaway investigation of lithium-ion battery by intentional EMI

With an increasing demand for electric vehicles and autonomous driving, many components of a vehicle are being replaced as electric components. This implicates the possibility of an increase in the malfunction of electric components due to unknown electromagnetic interferences. In this reason, malicious intentional electromagnetic interference (IEMI) is being considered as a growing threat for the current and next generation of automotive technology. In the first topic, the transfer function between the IEMI attacker and the engine control unit (ECU) circuit in an automobile is extracted to analyze how the IEMI affects the vehicle. In the second topic, to mimic the electromagnetic environment which can affect the battery system with inducing a current passing through the battery, the current is intentionally injected to the battery system with a bulk current injection (BCI) probe and it is investigated that how this coupled current can affect the battery with the parallel LC resonance of which the inductance comes from the wire and the capacitance comes from the bypass capacitor before voltage regulator module (VRM) --Abstract, page iv

Modeling of Rf Interference Caused by Solid-State Drive Noise

In this paper, modeling of RFI problem caused by a solid-state drive (SSD) in a laptop is proposed. Two noise sources (one outside and one inside a cavity) in the SSD are reconstructed as dipole moments with magnitude-only near-field scanning data. The dipole moment inside a cavity is then replaced by a Huygens\u27 box covering four side surfaces of the cavity using a numerical simulation. The noise voltage at an RF antenna port is calculated by combining the two reconstructed noise sources with measured transfer functions. The model is successfully validated through a comparison of the calculation with measurement results

Evolution of switchable aposematism: insights from individual-based simulations

Some defended prey animals can switch on their normally hidden aposematic signals. This switching may occur in reaction to predators' approach (pre-attack signals) or attack (post-attack signals). Switchable aposematism has been relatively poorly studied, but we can expect that it might bring a variety of benefits to an aposmetic organism. First, the switching could startle the predators (deimatism). Second, it could facilitate aversive learning. Third, it could minimize exposure or energetic expense, as the signal can be switched off. These potential benefits might offset costs of developing, maintaining and utilizing the switchable traits. Here we focused on the third benefit of switchability, the cost-saving aspect, and developed an individual-based computer simulation of predators and prey. In 88,128 model runs, we observed evolution of permanent, pre-attack, or post-attack aposematic signals of varying strength. We found that, in general, the pre-attack switchable aposematism may require moderate predator learning speed, high basal detectability, and moderate to high signal cost. On the other hand, the post-attack signals may arise under slow predator learning, low basal detectability and high signal cost. When predator population turnover is fast, it may lead to evolution of post-attack aposematic signals that are not conforming to the above tendency. We also suggest that a high switching cost may exert different selection pressure on the pre-attack than the post-attack switchable strategies. To our knowledge, these are the first theoretical attempts to systematically explore the evolution of switchable aposematism relative to permanent aposematism in defended prey. Our simulation model is capable of addressing additional questions beyond the scope of this article, and we open the simulation software, program manual and source code for free public use. © 2020 Song et al.1

Trails of ants converge or diverge through lens-shaped impediments, resembling principles of optics

Analogies across disciplines often indicate the existence of universal principles such as optimization, while the underlying proximate mechanisms may differ. It was reported recently that trails of ants refract at the border of substrates, on which walking speeds differ. This phenomenon is analogous to the travel-time-minimizing routes of light refracting at the borders between different media. Here, we further demonstrate that ant tracks converge or diverge across lens-shaped impediments similar to light rays through concave or convex optical lenses. The results suggest that the optical principle of travel time reduction may apply to ants. We propose a simple mathematical model that assumes nonlinear positive feedback in pheromone accumulation. It provides a possible explanation of the observed similarity between ant behavior and optics, and it is the first quantitative theoretical demonstration that pheromone-based proximate mechanisms of trail formation may produce this similarity. However, the future detailed empirical observations of ant behavior on impediment edges during the process of pheromone trail formation are needed in order to evaluate alternative explanations for this similarity. © 2020, The Author(s).1

Coupling Path Visualization and its Application in Preventing Electromagnetic Interference

A new method to visualize the coupling path is proposed to help solve electromagnetic compatibility problems. By using the reciprocity theorem and the concept of reaction, the coupling density coefficient (CC) is defined. Integration of the CC on closed surfaces equals the coupled power at the receiver. By plotting the CC on a set of surfaces from the source to the receiver, the coupling path, which traces the coupled power flow, can be visualized. All visualization procedures can be performed in a full-wave simulation tool, thus making the proposed method convenient to use. To validate and demonstrate the potential benefits of the new method, visualization of the coupling path in a realistic automotive intentional electromagnetic interference problem is presented. In addition, a mitigation solution based on the visualization result was examined

Intentional Electromagnetic Interference Source Reconstruction for Automotive Simulation

An intentional electromagnetic interference (IEMI) source has been reconstructed by using the dipole moment. The automotive simulations with the equivalent dipole can accurately characterize the costly IEMI experiments. Based on the measurement, the least square method is applied in source reconstruction. Importing the reconstructed source and the full-scale car model in simulation tool, fields inside the car are obtained. By comparing the simulation result with the experiment data, the automotive simulation model for IEMI is validated

Efficient Automotive Simulation using Reciprocity for Intentional Electromagnetic Interference

An efficient automotive simulation method for intentional electromagnetic interference (IEMI) is developed. As the full automotive simulation is computationally demanding, running the simulation for all possible IEMI attack locations is prohibitive. Therefore, a new methodology based on the reciprocity theorem is proposed to replace all regular simulations by one special simulation. The special simulation uses the reverse model which is defined by switching the location of source and observation point in the regular automotive simulation model. The reciprocity based simulation is validated by comparing the simulated results with all measured data in the IEMI experiment

Transfer Function Measurement for Automotive Intentional Electromagnetic Interference

The transfer function between the intentional electromagnetic interference (IEMI) attacker and the engine control unit (ECU) circuit in an automobile is extracted to analyze how the IEMI affects the vehicle. A log-periodic antenna is used as the IEMI aggressor based on the frequency domain measurement and the transfer function of the log-periodic antenna is compared with the transfer function of the standard mesoband source generator measured in the time domain. The electric field of the standard source is regenerated with the transfer function of the log-periodic antenna. It is then compared with the original field of the standard source to validate the transfer function of the log-periodic antenna. Since the D-dot sensor is used to measure radiated field in the time domain, a noise in low frequency region is amplified and it is investigated

A novel algorithm for robust estimation of ants' speed on convoluted trajectories derived from their gait pattern

Accurate measurements of travel distance and the corresponding speed are crucial for the analysis of animal movements. Particularly, the trajectories of ants were used in numerous behavioral studies. However, measurements of travel distance involve the dilemma of setting the proper time window: Estimates from a short time window are vulnerable to spatial errors in observation, while estimates from a long time window lead to an underestimation of the travel distance. To overcome these difficulties, we propose a novel algorithm that successively interpolates two consecutive points of an ant's trajectory for a given time window by embracing the alternating tripod gait and other gait patterns of ants. We demonstrate that this algorithm is more reliable compared with the conventional method of travel distance estimation based on the sum of the consecutive straight-line displacement (SLD). After obtaining speed estimates for a range of sampling time windows, we applied a fitting method that can estimate the actual speed without prior knowledge of spatial error distribution. We compared results from several methods of speed estimation extracted from the empirical and simulated data of ant trajectories. The accuracy of our algorithm was comparable with or much higher than the accuracy of the sum over the consecutive SLD with optimal window length. Hence, subjective selection of the sampling time window can be avoided by using the proposed algorithm. We provide software that enables empirical scientists to utilize the proposed methods rather than the conventional SLD method of distance and speed estimation. © 2023 The Authors. Ecosphere published by Wiley Periodicals LLC on behalf of The Ecological Society of America.TRU

Directional raids by army ants as an adaption to patchily distributed food: a simulation model

A typical colony of Neotropical army ants (subfamily Ecitoninae) regularly raids a large area around their bivouac by forming a narrow directional column that can reach up to one hundred meters in length. The raid is finished and then relaunched 12–17 times, each time toward different orientation. After completing all bouts the colony relocates to a new area. A hypothetical alternative to this foraging mode is raiding radially and symmetrically by expanding the search front in every direction like a circular bubble. Using an existing agent-based modeling software that simulates army ants’ behavior, we compared the two possible modes of foraging in different food distributions. Regardless of the food patch abundance, the radial raiding was superior to the directional raiding when food patches had low quality, and the directional raiding was favorable when the patches were rich. In terms of energy efficiency, the radial raiding was the better strategy in a wide range of conditions. In contrast, the directional raiding tended to yield more food per coverage area. Based on our model, we suggest that the directional raiding by army ants is an adaptation to the habitats with abundance of high-quality food patches. This conclusion fits well with the ecology of army ants