Despite extensive study of human locomotion over many years, obstacles continue to hinder the simulation of human movement in the exploration of musculoskeletal factors and clinical conditions. Recent applications of reinforcement learning (RL) methods show encouraging results in simulating human movement, highlighting the underlying musculoskeletal mechanisms. While these simulations are frequently conducted, they often do not accurately reflect natural human locomotion because the majority of reinforcement strategies have yet to leverage any reference data pertaining to human movement. To overcome these obstacles, this research developed a reward function incorporating trajectory optimization rewards (TOR) and bio-inspired rewards, including those derived from reference motion data gathered by a single Inertial Measurement Unit (IMU) sensor. For the purpose of capturing reference motion data, sensors were strategically placed on the participants' pelvises. We also adapted the reward function, which benefited from earlier studies regarding TOR walking simulations. Analysis of the experimental results revealed that simulated agents, equipped with the modified reward function, exhibited enhanced accuracy in mimicking the IMU data collected from participants, thereby producing more realistic simulations of human locomotion. The agent's training process demonstrated heightened convergence thanks to the IMU data, structured as a bio-inspired defined cost. The models with reference motion data converged faster, showing a marked improvement in convergence rate over those without. Subsequently, a more rapid and extensive simulation of human movement becomes feasible across diverse environments, resulting in enhanced simulation outcomes.
Deep learning's widespread adoption in diverse applications is tempered by its susceptibility to adversarial data. A generative adversarial network (GAN) was instrumental in creating a robust classifier designed to counter this vulnerability. A novel generative adversarial network (GAN) model and its implementation are explored in this paper for the purpose of defending against adversarial attacks leveraging gradient information with L1 and L2 constraints. The proposed model, although inspired by related work, incorporates multiple novel designs, including a dual generator architecture, four new generator input formats, and two unique implementation approaches featuring vector outputs constrained by L and L2 norms. In response to the limitations of adversarial training and defensive GAN strategies, such as gradient masking and the intricate training processes, novel GAN formulations and parameter adjustments are presented and critically examined. Moreover, an evaluation of the training epoch parameter was conducted to ascertain its influence on the final training outcomes. The experimental results strongly support the conclusion that a more effective GAN adversarial training approach should use enhanced gradient information from the target classifier. Subsequently, the outcomes underscore GANs' prowess in overcoming gradient masking and generating powerful data augmentations. The model's robustness against PGD L2 128/255 norm perturbation is impressive, with an accuracy exceeding 60%, but drops significantly to about 45% for PGD L8 255 norm perturbations. The results show that the proposed model's constraints exhibit transferable robustness. Subsequently, a trade-off between robustness and accuracy was found, interwoven with overfitting issues and the limited generalizability of the generator and the classifier. check details The forthcoming discussion will encompass these limitations and future work ideas.
In contemporary car keyless entry systems (KES), ultra-wideband (UWB) technology is emerging as a novel method for pinpointing keyfobs, owing to its precise localization and secure communication capabilities. Nonetheless, vehicle distance estimations are often plagued by substantial errors originating from non-line-of-sight (NLOS) effects, heightened by the presence of the car. In light of the NLOS problem, various strategies have been undertaken to reduce the inaccuracies in calculating distances between points or to predict the tag's position utilizing neural network models. Nonetheless, the model exhibits some deficiencies, such as low precision, a predisposition towards overfitting, or a substantial parameter load. We recommend a fusion strategy, comprised of a neural network and a linear coordinate solver (NN-LCS), to effectively handle these issues. Distance and received signal strength (RSS) features are individually extracted using two fully connected layers, and subsequently fused in a multi-layer perceptron to compute estimated distances. For distance correcting learning, the least squares method, crucial for error loss backpropagation in neural networks, is proven feasible. As a result, the model's end-to-end design produces the localization results without any intermediate operations. The findings demonstrate that the suggested methodology boasts high accuracy and a compact model size, facilitating seamless deployment on resource-constrained embedded devices.
Industrial and medical applications both rely heavily on gamma imagers. Iterative reconstruction methods, employing the system matrix (SM) as a critical component, are commonly used in modern gamma imagers to produce high-quality images. An accurate signal model (SM) can be obtained via a calibration experiment employing a point source encompassing the entire field of view, albeit at the price of prolonged calibration time to mitigate noise, a significant constraint in real-world applications. A time-efficient SM calibration technique for a 4-view gamma imager is described, encompassing short-term SM measurements and deep learning for noise reduction. The key procedure entails fragmenting the SM into numerous detector response function (DRF) image components, classifying these DRFs into varied groups through a dynamically adjusted K-means clustering approach to manage variations in sensitivity, and ultimately individually training distinct denoising deep networks for each DRF category. We scrutinize the efficacy of two denoising networks, evaluating them in comparison to a conventional Gaussian filtering technique. The results on denoised SM using deep networks indicate equivalent imaging performance compared to the long-term SM measurements. By optimizing the SM calibration process, the time required for calibration has been reduced drastically from 14 hours to 8 minutes. The proposed SM denoising method shows a compelling potential for enhancing the productivity of the four-view gamma imager, and its general suitability for other imaging systems needing a calibration stage is evident.
Siamese network-based visual tracking techniques have achieved impressive results on large-scale benchmarks; however, the problem of correctly identifying the target from similar-appearing distractors continues to be a significant hurdle. To resolve the previously discussed issues, we propose a novel global context attention module for visual tracking. The proposed module captures and condenses the encompassing global scene information to modify the target embedding, thereby boosting its discriminative power and resilience. Our global context attention module, receiving a global feature correlation map representing a given scene, deduces contextual information. This information is used to create channel and spatial attention weights, modulating the target embedding to hone in on the relevant feature channels and spatial parts of the target object. Our tracking algorithm's performance, tested on a range of large-scale visual tracking datasets, is superior to the baseline algorithm while achieving comparable real-time speed. Subsequent ablation experiments provided validation of the proposed module's effectiveness, showcasing our tracking algorithm's improvements in various challenging aspects of visual tracking tasks.
The clinical utility of heart rate variability (HRV) features extends to sleep stage classification, and ballistocardiograms (BCGs) enable non-intrusive estimations of these metrics. check details Traditional electrocardiography is the gold standard for estimating heart rate variability (HRV), however, bioimpedance cardiography (BCG) and electrocardiograms (ECGs) often produce different heartbeat interval (HBI) measurements, resulting in variations in the calculated HRV indices. The study scrutinizes the potential of utilizing BCG-linked HRV features to categorize sleep stages, evaluating the effect of these time disparities on the parameters of interest. A collection of synthetic time offsets were implemented to simulate the discrepancies in heartbeat interval measurements between BCG and ECG, subsequently leveraging the generated HRV features to classify sleep stages. check details We then investigate the link between the average absolute error in HBIs and the consequent accuracy of sleep stage determination. In extending our prior work on heartbeat interval identification algorithms, we show that the simulated timing variations we employed closely represent the errors found in actual heartbeat interval measurements. Sleep-staging procedures using BCG information yield comparable results to ECG-based ones; a 60-millisecond error range expansion in the HBI metric leads to a rise in sleep-scoring errors, growing from 17% to 25%, according to our analyzed data set.
A fluid-filled RF MEMS (Radio Frequency Micro-Electro-Mechanical Systems) switch is proposed and its design is elaborated upon in this current study. In order to examine the influence of insulating liquids on the RF MEMS switch, simulations using air, water, glycerol, and silicone oil as dielectric mediums were undertaken to investigate the effect on drive voltage, impact velocity, response time, and switching capacity. Insulating liquid, when used to fill the switch, leads to a reduction in both the driving voltage and the impact velocity of the upper plate colliding with the lower plate. The elevated dielectric constant of the filling medium is associated with a diminished switching capacitance ratio, which correspondingly affects the switch's operational capabilities. A comprehensive evaluation of the switch's threshold voltage, impact velocity, capacitance ratio, and insertion loss, conducted across various media (air, water, glycerol, and silicone oil), ultimately designated silicone oil as the preferred liquid filling medium for the switch.