727 research outputs found
Convolutional Radio Modulation Recognition Networks
We study the adaptation of convolutional neural networks to the complex
temporal radio signal domain. We compare the efficacy of radio modulation
classification using naively learned features against using expert features
which are widely used in the field today and we show significant performance
improvements. We show that blind temporal learning on large and densely encoded
time series using deep convolutional neural networks is viable and a strong
candidate approach for this task especially at low signal to noise ratio
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Electric Vehicle - Smart Grid Integration: Load Modeling, Scheduling, and Cyber Security
The modern world has witnessed the surge of electric vehicles (EVs) driven by government policy worldwide to reduce transportation’s dependence on fossil fuels. According to (Slowik, 2019), the global EV market has grown sharply with the annual light-duty EV sales surpassing 2 million in 2018, which is about a 70% increase from 2017. The increase in EV population implies the rise in energy demand, and that introduces new challenges to the electricity sector. EV charging load demand in high penetration scenarios, which is foreseen, may lead to stability and quality issues in power grids. Generation capacity and the electricity infrastructure upgrade may be required to address those issues; however, it increases generation costs significantly. The most common EV chargers installed today deliver around 7 kW of power, which is over four times that of an average household power consumption in the US. EV charging load often shows two peaks in a day, one in the morning when people plug in the EV at the workplace and the other in the evening when people get home from work. Without proper energy management for EV charging, the vast power demand due to a large number of plugged-in EVs can stress the electric grid, degrade the electric power quality, and impact the wholesale electricity market. Although an EV battery may store energy up to 80 kWh, which requires more than 10 hours to charge at 7kW from empty, we found that most EVs need only 12 kWh per charge or 1.7 hours at 7 kW to meet daily commute requirement while they stay in the parking garage for a more extended period. This implies that EVs can have considerable time-flexibility for charging, and it is not necessary to start chargingright after plugging in, which is likely to result in the charging power add-up. A proper EV charging schedule can well allocate the charging load to prevent power peaks. Therefore, EV charging scheduling can play a significant role in mitigating the adverse effects of vast EV charging demand without upgrading the power grid capacity.To optimize the EV charging schedule while satisfies EVs’ charging demand, each EV’s stay duration and energy need are essential parameters for the optimization. Those parameters are based on predictions to minimize human intervention. Nonetheless, the uncertainty of EV user behavior poses a challenge to the prediction accuracy. Therefore, this dissertation demonstrates an ensemble machine learning-based method to model and predict the EV loads accurately, thereby improving the performance of EV charging scheduling.On the other hand, this smart EV-grid integration, which requires massive communication, including collecting, transmitting, and distributing real-time data within the network, makes it more susceptible to cyber-physical threats. Potential breaches could not only affect grid operation but also reduce consumers’ willingness to adopting EVs over conventional fuel-powered vehicles. This dissertation also presents the vulnerability analysis and risk assessment for a smart EV charging system to develop the countermeasures to secure the network. Also, while it is inevitable that the security has flaws, this dissertation provides a novel anomaly detection approach based on the invariant correlations of different measurements within the EV charging network
Detection and fine-grained classification of cyberbullying events
In the current era of online interactions, both positive and negative experiences are abundant on the Web. As in real life, negative experiences can have a serious impact on youngsters. Recent studies have reported cybervictimization rates among teenagers that vary between 20% and 40%. In this paper, we focus on cyberbullying as a particular form of cybervictimization and explore its automatic detection and fine-grained classification. Data containing cyberbullying was collected from the social networking site Ask.fm. We developed and applied a new scheme for cyberbullying annotation, which describes the presence and severity of cyberbullying, a post author's role (harasser, victim or bystander) and a number of fine-grained categories related to cyberbullying, such as insults and threats. We present experimental results on the automatic detection of cyberbullying and explore the feasibility of detecting the more fine-grained cyberbullying categories in online posts. For the first task, an F-score of 55.39% is obtained. We observe that the detection of the fine-grained categories (e.g. threats) is more challenging, presumably due to data sparsity, and because they are often expressed in a subtle and implicit way
Exploring the Relationship between Architecture and Adversarially Robust Generalization
Adversarial training has been demonstrated to be one of the most effective
remedies for defending adversarial examples, yet it often suffers from the huge
robustness generalization gap on unseen testing adversaries, deemed as the
adversarially robust generalization problem. Despite the preliminary
understandings devoted to adversarially robust generalization, little is known
from the architectural perspective. To bridge the gap, this paper for the first
time systematically investigated the relationship between adversarially robust
generalization and architectural design. Inparticular, we comprehensively
evaluated 20 most representative adversarially trained architectures on
ImageNette and CIFAR-10 datasets towards multiple `p-norm adversarial attacks.
Based on the extensive experiments, we found that, under aligned settings,
Vision Transformers (e.g., PVT, CoAtNet) often yield better adversarially
robust generalization while CNNs tend to overfit on specific attacks and fail
to generalize on multiple adversaries. To better understand the nature behind
it, we conduct theoretical analysis via the lens of Rademacher complexity. We
revealed the fact that the higher weight sparsity contributes significantly
towards the better adversarially robust generalization of Transformers, which
can be often achieved by the specially-designed attention blocks. We hope our
paper could help to better understand the mechanism for designing robust DNNs.
Our model weights can be found at http://robust.art
Translating away Translationese without Parallel Data
Translated texts exhibit systematic linguistic differences compared to
original texts in the same language, and these differences are referred to as
translationese. Translationese has effects on various cross-lingual natural
language processing tasks, potentially leading to biased results. In this
paper, we explore a novel approach to reduce translationese in translated
texts: translation-based style transfer. As there are no parallel
human-translated and original data in the same language, we use a
self-supervised approach that can learn from comparable (rather than parallel)
mono-lingual original and translated data. However, even this self-supervised
approach requires some parallel data for validation. We show how we can
eliminate the need for parallel validation data by combining the
self-supervised loss with an unsupervised loss. This unsupervised loss
leverages the original language model loss over the style-transferred output
and a semantic similarity loss between the input and style-transferred output.
We evaluate our approach in terms of original vs. translationese binary
classification in addition to measuring content preservation and target-style
fluency. The results show that our approach is able to reduce translationese
classifier accuracy to a level of a random classifier after style transfer
while adequately preserving the content and fluency in the target original
style.Comment: Accepted at EMNLP 2023, Main Conferenc
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