Cardinality estimation is a fundamental task in database query processing and optimization. Unfortunately, the accuracy of traditional estimation techniques is poor resulting in non-optimal query execution plans. With the recent expansion of machine learning into the field of data management, there is the general notion that data analysis, especially neural networks, can lead to better estimation accuracy. Up to now, all proposed neural network approaches for the cardinality estimation follow a global approach considering the whole database schema at once. These global models are prone to sparse data at training leading to misestimates for queries which were not represented in the sample space used for generating training queries. To overcome this issue, we introduce a novel local-oriented approach in this paper, therefore the local context is a specific sub-part of the schema. As we will show, this leads to better representation of data correlation and thus better estimation accuracy. Compared to global approaches, our novel approach achieves an improvement by two orders of magnitude in accuracy and by a factor of four in training time performance for local models.

<p>Spiking Neural Networks (SNNs) have recently attracted significant research interest as the third generation of artificial neural networks that can enable low-power event-driven data analytics. We propose ANN-SNN conversion using “soft re-set” spiking neuron model, referred to as Residual Membrane Potential (RMP) spiking neuron, which retains the “resid- ual” membrane potential above threshold at the firing instants. In addition, we propose a time-based coding scheme, named Temporal-Switch-Coding (TSC), and a corresponding TSC spiking neuron model. Each input image pixel is presented using two spikes with opposite polarity and the timing between the two spiking instants is proportional to the pixel intensity. We demonstrate near loss-less ANN-SNN conversion using RMP neurons for VGG-16, ResNet-20, and ResNet-34 SNNs on challenging datasets including CIFAR-10, CIFAR-100, and ImageNet. With the help of TSC coding, it achieves 7-14.5× less inference latency, and 30-60× fewer addition operations and memory accesses per inference across datasets compared to the state of the art (SOTA) SNN models. In the second part of the thesis, we propose a new type of recurrent neural network (RNN) architecture, named Os- cillatory Fourier Neural Network (O-FNN). We demonstrate that O-FNN is mathematically equivalent to a simplified form of Discrete Fourier Transform applied onto periodical activa- tion. In particular, the computationally intensive back-propagation through time in training is eliminated, leading to faster training while achieving the SOTA inference accuracy in a diverse group of sequential tasks. For instance, applying the proposed model to sentiment analysis on IMDB review dataset reaches 89.4% test accuracy within 5 epochs, accompanied by over 35x reduction in the model size compared to Long Short-Term Memory (LSTM). The proposed novel RNN architecture is well poised for intelligent sequential processing in resource constrained hardware.</p>

Computer vision in the area of medical imaging has rapidly improved during recent years as a consequence of developments in deep learning and explainability algorithms. In addition, imaging in nuclear medicine is becoming increasingly sophisticated, with the emergence of targeted radiotherapies that enable treatment and imaging on a molecular level (“theranostics”) where radiolabeled targeted molecules are directly injected into the bloodstream. Based on our recent work, we present two use-cases in nuclear medicine as follows: first, the impact of automated organ segmentation required for personalized dosimetry in patients with neuroendocrine tumors and second, purely data-driven identification and verification of brain regions for diagnosis of Parkinson’s disease. Convolutional neural network was used for automated organ segmentation on computed tomography images. The segmented organs were used for calculation of the energy deposited into the organ-at-risk for patients treated with a radiopharmaceutical. Our method resulted in faster and cheaper dosimetry and only differed by 7% from dosimetry performed by two medical physicists. The identification of brain regions, however was analyzed on dopamine-transporter single positron emission tomography images using convolutional neural network and explainability, i.e., layer-wise relevance propagation algorithm. Our findings confirm that the extra-striatal brain regions, i.e., insula, amygdala, ventromedial prefrontal cortex, thalamus, anterior temporal cortex, superior frontal lobe, and pons contribute to the interpretation of images beyond the striatal regions. In current common diagnostic practice, however, only the striatum is the reference region, while extra-striatal regions are neglected. We further demonstrate that deep learning-based diagnosis combined with explainability algorithm can be recommended to support interpretation of this image modality in clinical routine for parkinsonian syndromes, with a total computation time of three seconds which is compatible with busy clinical workflow. Overall, this thesis shows for the first time that deep learning with explainability can achieve results competitive with human performance and generate novel hypotheses, thus paving the way towards improved diagnosis and treatment in nuclear medicine.

This thesis will cover the topic of cyber security in vehicles. Current vehicles contain many computers which communicate over a controller area network. This network has many vulnerabilities which can be leveraged by attackers. To combat these attackers, intrusion detection systems have been implemented. The latest research has mostly focused on the use of deep learning techniques for these intrusion detection systems. However, these deep learning techniques are not foolproof and possess their own security vulnerabilities. One such vulnerability comes in the form of adversarial samples. These are attacks that are manipulated to evade detection by these intrusion detection systems. In this thesis, the aim is to show that the known vulnerabilities of deep learning techniques are also present in the current state-of-the-art intrusion detection systems. The presence of these vulnerabilities shows that these deep learning based systems are still to immature to be deployed in actual vehicles. Since if an attacker is able to use these weaknesses to circumvent the intrusion detection system, they can still control many parts of the vehicles such as the windows, the brakes and even the engine. Current research regarding deep learning weaknesses has mainly focused on the image recognition domain. Relatively little research has investigated the influence of these weaknesses for intrusion detection, especially on vehicle networks. To show these weaknesses, firstly two baseline deep learning intrusion detection systems were created. Additionally, two state-of-the-art systems from recent research papers were recreated. Afterwards, adversarial samples were generated using the fast gradient-sign method on one of the baseline systems. These adversarial samples were then used to show the drop in performance of all systems. The thesis shows that the adversarial samples negatively impact the two baseline models and one state-of-the-art model. The state-of-the-art model’s drop in performance goes as high as 60% in the f1-score. Additionally, some of the adversarial samples need as little as 2 bits to be changed in order to evade the intrusion detection systems. / Detta examensarbete kommer att täcka ämnet cybersäkerhet i fordon. Nuvarande fordon innehåller många datorer som kommunicerar över ett så kallat controller area network. Detta nätverk har många sårbarheter som kan utnyttjas av angripare. För att bekämpa dessa angripare har intrångsdetekteringssystem implementerats. Den senaste forskningen har mestadels fokuserat på användningen av djupinlärningstekniker för dessa intrångsdetekteringssystem. Dessa djupinlärningstekniker är dock inte idiotsäkra och har sina egna säkerhetsbrister. En sådan sårbarhet kommer i form av kontradiktoriska prover. Dessa är attacker som manipuleras för att undvika upptäckt av dessa intrångsdetekteringssystem. I det här examensarbetet kommer vi att försöka visa att de kända sårbarheterna hos tekniker för djupinlärning också finns i de nuvarande toppmoderna systemen för intrångsdetektering. Förekomsten av dessa sårbarheter visar att dessa djupinlärningsbaserade system fortfarande är för omogna för att kunna användas i verkliga fordon. Eftersom om en angripare kan använda dessa svagheter för att kringgå intrångsdetekteringssystemet, kan de fortfarande kontrollera många delar av fordonet som rutorna, bromsarna och till och med motorn. Aktuell forskning om svagheter i djupinlärning har främst fokuserat på bildigenkänningsdomänen. Relativt lite forskning har undersökt inverkan av dessa svagheter för intrångsdetektering, särskilt på fordonsnätverk. För att visa dessa svagheter skapades först två baslinjesystem för djupinlärning intrångsdetektering. Dessutom återskapades två toppmoderna system från nya forskningsartiklar. Efteråt genererades motstridiga prover med hjälp av den snabba gradient-teckenmetoden på ett av baslinjesystemen. Dessa kontradiktoriska prover användes sedan för att visa nedgången i prestanda för alla system. Avhandlingen visar att de kontradiktoriska proverna negativt påverkar de två baslinjemodellerna och en toppmodern modell. Den toppmoderna modellens minskning av prestanda går så högt som 60% i f1-poängen. Dessutom behöver några av de kontradiktoriska samplen så lite som 2 bitar att ändras för att undvika intrångsdetekteringssystem.

Articular chondral lesions in the knee joint can be diagnosed at an early stage using MRI. Segmenting and visualizing lesions and the overall joint structure allows improved communication between the radiologist and referring physician. It can also be of help when determining diagnosis or conducting surgical planning. Although there are a variety of studies proving good results of segmentation of larger structures such as bone and cartilage in the knee, there are no studies available researching segmentation of articular cartilage lesions. Automating the segmentation will save time and money since manual segmentation is very time-consuming. In this thesis, a U-Net based convolutional neural network is used to perform automatic segmentation of chondral lesions located on the distal part of the femur, in the knee joint. Using two different techniques, batch normalization and dropout, a network was trained and tested using MRI sequences collected from Episurf Medical's database. The network was then evaluated using a segmentation approach and a detection approach. For the segmentation approach, the highest achieved dice coefficient and sensitivity of 0.4059 ± 0.1833 and 0.4591 ± 0.2387, was obtained using batch normalization and 260 training subjects, consisting of MRI sequence and corresponding masks. Using a detection approach, the predicted output could correctly identify 81.8% of the chondral lesions in the MRI sequences. Although there is a need for improvement of technique and datasets used in this thesis, the achieved results show prerequisites for future improvement and possible implementation. / Skador i knäledens brosk kan diagnostiseras i ett tidigt stadie med hjälp av MR. Segmentering och visualisering av skadorna, samt ledens struktur i helhet, bidrar till en förbättrad kommunikation mellan radiolog och remitterande läkare. Det kan också underlätta för att ställa diagnos eller utföra operationsplanering. I dagsläget finns flertalet studier som påvisar goda resultat för segmentering av större strukturer, t.ex. ben och brosk. Det finns dock få studier som studerar segmentering av skador i ledbrosk. Genom att automatisera segmenteringsprocessen kan både tid och pengar sparas. Detta eftersom att manuell segmentering är mycket tidskrävande. I detta arbete kommer ett U-Net baserat convolutional neural network att användas för att utföra automatisk segmentering av skador på distala femur i knäleden. Nätverket kommer att tränas med två olika tekniker, batch normalization och dropout. Nätverket kommer att tränas med data som är hämtad från Episurf Medicals databas och består av MR sekvenser. Nätverket kommer att tränas och utvärderas med hjälp av två metoder, en segmenteringsmetod och detekteringsmetod. Den högsta uppnådda dice koefficienten och sensitiviteten vid utvärderingen av segmenteringsmetoden uppmätte 0,4059 ± 0,1833 och 0,4591 ± 0,2387. Den upnåddes med hjälp av batch normalization och 260 MR sekvenser för träning och testning. För detektionsmetoden kunde programmet identifiera 81,8% av skadorna synliga på MR sekvenserna. Även om tekniken och datan som används behöver optimeras, så visar det uppnådda resultatet på bra förutsättningar för fortsatta studier och i framtiden möjligen även implementering av tekniken.

Named Entity Recognition (NER) is a critical task in Natural Language Processing (NLP), and recent advancements in language model pre-training have significantly improved its performance. However, this improvement is not universally applicable due to a lack of large pre-training datasets or computational budget for smaller languages. This study explores the viability of fine-tuning an English and a multilingual model on a Swedish NER task, compared to a model trained solely on Swedish. Our methods involved training these models and measuring their performance using the F1-score metric. Despite fine-tuning, the Swedish model outperformed both the English and multilingual models by 3.0 and 9.0 percentage points, respectively. The performance gap between the English and Swedish models during fine-tuning decreased from 19.8 to 9.0 percentage points. This suggests that while the Swedish model achieved the best performance, fine-tuning can substantially enhance the performance of English and multilingual models for Swedish NER tasks. / Inom området för Natural Language Processing (NLP) är identifiering av namngivna entiteter (NER) en viktig problemtyp. Tack vare senaste tidens framsteg inom förtränade språkmodeller har modellernas prestanda på problemtypen ökat kraftigt. Denna förbättring kan dock inte tillämpas överallt på grund av en brist på omfattande dataset för förträning eller tillräcklig datorkraft för mindre språk. I denna studie undersöks potentialen av fine-tuning på både en engelsk, en svensk och en flerspråkig modell för en svensk NER-uppgift. Dessa modeller tränades och deras effektivitet bedömdes genom att använda F1-score som mått på prestanda. Även med fine-tuning var den svenska modellen bättre än både den engelska och flerspråkiga modellen, med en skillnad på 3,0 respektive 9,0 procentenheter i F1-score. Skillnaden i prestandan mellan den engelska och svenska modellen minskade från 19,8 till 9,0 procentenheter efter fine-tuning. Detta indikerar att även om den svenska modellen var mest framgångsrik, kan fine-tuning av engelska och flerspråkiga modeller betydligt förbättra prestandan för svenska NER-uppgifter.

Emerging sensors and intelligent traffic technologies provide extensive data sets in a traffic network. However, realizing the full potential of such data sets for a unique representation of real-world states is challenging due to data accuracy, noise, and temporal-spatial resolution. Data assimilation is a known group of methodological approaches that exploit physics-informed traffic models and data observations to perform short-term predictions of the traffic state in freeway environments. At the same time, neural networks capture high non-linearities, similar to those presented in traffic networks. Despite numerous works applying different variants of Kalman filters, the possibility of traffic state estimation with deep-learning-based methodologies is only partially explored in the literature. We present a deep-learning modeling approach to perform traffic state estimation on large freeway networks. The proposed framework is trained on local observations from static and moving sensors and identifies differences between well-trusted data and model outputs. The detected patterns are then used throughout the network, even where there are no available observations to estimate fundamental traffic quantities. The preliminary results of the work highlight the potential of deep learning for traffic state estimation.

The rise of convolutional neural networks (CNNs) in the context of computer vision has occurred in tandem with the advancement of depth sensing technology. Depth cameras are capable of yielding two-dimensional arrays storing at each pixel the distance from objects and surfaces in a scene from a given sensor, aligned with a regular color image, obtaining so-called RGBD images. Inspired by prior models in the literature, this work develops a suite of RGBD CNN models to tackle the challenging tasks of object detection, instance segmentation, and semantic segmentation. Prominent architectures for object detection and image segmentation are modified to incorporate dual backbone approaches inputting RGB and depth images, combining features from both modalities through the use of novel fusion modules. For each task, the models developed are competitive with state-of-the-art RGBD architectures. In particular, the proposed RGBD object detection approach achieves 53.5% mAP on the SUN RGBD 19-class object detection benchmark, while the proposed RGBD semantic segmentation architecture yields 69.4% accuracy with respect to the SUN RGBD 37-class semantic segmentation benchmark. An original 13-class RGBD instance segmentation benchmark is introduced for the SUN RGBD dataset, for which the proposed model achieves 38.4% mAP. Additionally, an original depth-aware panoptic segmentation model is developed, trained, and tested for new benchmarks conceived for the NYUDv2 and SUN RGBD datasets. These benchmarks offer researchers a baseline for the task of RGBD panoptic segmentation on these datasets, where the novel depth-aware model outperforms a comparable RGB counterpart.

<p>This research focused on developing adaptable models and protocols for early warning systems for forecasting plant diseases and datasets. It compared the performance of deep learning models in predicting soybean rust disease outbreaks using three years of public epidemiological data and gridded weather data. The models selected were a dense network and a Long Short-Term Memory (LSTM) network. The objectives included evaluating the effectiveness of small citizen science datasets and gridded meteorological weather in sequential forecasting, assessing the ideal window size and important inputs, and exploring the generalizability of the model protocol and models to other diseases. The model protocol was developed using a soybean rust dataset. Both the dense and the LSTM networks produced accuracies of over 90% during optimization. When tested for forecasting, both networks could forecast with an accuracy of 85% or higher over various window sizes. Experiments on window size indicated a minimum input of 8 -11 days. Generalizability was demonstrated by applying the same protocol to a southern corn rust dataset, resulting in 87.8% accuracy. In addition, transfer learning and pre-trained models were tested. Direct transfer learning between disease was not successful, while pre training models resulted both positive and negative results. Preliminary results are reported for building generalizable disease models using epidemiological and weather data that researchers could apply to generate forecasts for new diseases and locations.</p>

<p> Trajectory planning is a field with widespread utility, and imitation learning pipelines<br> show promise as an accessible training method for trajectory planning. MPNet is the state<br> of the art for imitation learning with respect to success rates. MPNet has two general<br> components to its runtime: a neural network predicts the location of the next anchor point in<br> a trajectory, and then planning infrastructure applies sampling-based techniques to produce<br> near-optimal, collision-less paths. This distinction between the two parts of MPNet prompts<br> investigation into the role of the neural architectures in the Neural Motion Planning pipeline,<br> to discover where improvements can be made. This thesis seeks to explore the importance<br> of neural architecture choice by removing the planning structures, and comparing MPNet’s<br> feedforward anchor point predictor with that of a continuous model trained to output a<br> continuous trajectory from start to goal. A new state of the art model in continuous learning<br> is the Neural Flow model. As a continuous model, it possess a low standard deviation runtime<br> which can be properly leveraged in the absence of planning infrastructure. Neural Flows also<br> output smooth, continuous trajectory curves that serve to reduce noisy path outputs in the<br> absence of lazy vertex contraction. This project analyzes the performance of MPNet, Resnet<br> Flow, and Coupling Flow models when sampling-based planning tools such as dropout, lazy<br> vertex contraction, and replanning are removed. Each neural planner is trained end-to-end in<br> an imitation learning pipeline utilizing a simple feedforward encoder, a CNN-based encoder,<br> and a Pointnet encoder to encode the environment, for purposes of comparison. Results<br> indicate that performance is competitive, with Neural Flows slightly outperforming MPNet’s<br> success rates on our reduced dataset in Simple2D, and being slighty outperformed by MPNet<br> with respect to collision penetration distance in our UR5 Cubby test suite. These results<br> indicate that continuous models can compete with the performance of anchor point predictor<br> models when sampling-based planning techniques are not applied. Neural Flow models also<br> have other benefits that anchor point predictors do not, like continuity guarantees, the ability<br> to select a proportional location in a trajectory to output, and smoothness. </p>