Alexander Wong's research while affiliated with University of Waterloo and other places

Publications (57)

Preprint
Full-text available
Computer vision and machine learning are playing an increasingly important role in computer-assisted diagnosis; however, the application of deep learning to medical imaging has challenges in data availability and data imbalance, and it is especially important that models for medical imaging are built to be trustworthy. Therefore, we propose TRUDLMI...
Article
Full-text available
Background Understanding what factors lead to youth polysubstance use (PSU) patterns and how the transitions between use patterns can inform the design and implementation of PSU prevention programs. We explore the dynamics of PSU patterns from a large cohort of Canadian secondary school students using machine learning techniques. Methods We employ...
Preprint
Model pruning can enable the deployment of neural networks in environments with resource constraints. While pruning may have a small effect on the overall performance of the model, it can exacerbate existing biases into the model such that subsets of samples see significantly degraded performance. In this paper, we introduce the performance weighte...
Preprint
Full-text available
Deep convolutional neural network (CNN) training via iterative optimization has had incredible success in finding optimal parameters. However, modern CNN architectures often contain millions of parameters. Thus, any given model for a single architecture resides in a massive parameter space. Models with similar loss could have drastically different...
Preprint
Autonomous bin picking poses significant challenges to vision-driven robotic systems given the complexity of the problem, ranging from various sensor modalities, to highly entangled object layouts, to diverse item properties and gripper types. Existing methods often address the problem from one perspective. Diverse items and complex bin scenes requ...
Preprint
As the global population continues to face significant negative impact by the on-going COVID-19 pandemic, there has been an increasing usage of point-of-care ultrasound (POCUS) imaging as a low-cost and effective imaging modality of choice in the COVID-19 clinical workflow. A major barrier with widespread adoption of POCUS in the COVID-19 clinical...
Preprint
Light guide plates are essential optical components widely used in a diverse range of applications ranging from medical lighting fixtures to back-lit TV displays. An essential step in the manufacturing of light guide plates is the quality inspection of defects such as scratches, bright/dark spots, and impurities. This is mainly done in industry thr...
Preprint
Photovoltaic cells are electronic devices that convert light energy to electricity, forming the backbone of solar energy harvesting systems. An essential step in the manufacturing process for photovoltaic cells is visual quality inspection using electroluminescence imaging to identify defects such as cracks, finger interruptions, and broken cells....
Preprint
Ever since the declaration of COVID-19 as a pandemic by the World Health Organization in 2020, the world has continued to struggle in controlling and containing the spread of the COVID-19 pandemic caused by the SARS-CoV-2 virus. This has been especially challenging with the rise of the Omicron variant and its subvariants and recombinants, which has...
Preprint
Full-text available
The International Classification of Diseases (ICD) system is the international standard for classifying diseases and procedures during a healthcare encounter and is widely used for healthcare reporting and management purposes. Assigning correct codes for clinical procedures is important for clinical, operational, and financial decision-making in he...
Preprint
Full-text available
Understanding what factors lead to youth polysubstance use (PSU) patterns and how the transitions between use patterns can inform the design and implementation of PSU prevention programs. We explore the dynamics of PSU patterns from a large cohort of Canadian secondary school students using machine learning techniques.
Preprint
Full-text available
There has been increasing interest in smart factories powered by robotics systems to tackle repetitive, laborious tasks. One impactful yet challenging task in robotics-powered smart factory applications is robotic grasping: using robotic arms to grasp objects autonomously in different settings. Robotic grasping requires a variety of computer vision...
Preprint
Full-text available
Lexical substitution is the task of generating meaningful substitutes for a word in a given textual context. Contextual word embedding models have achieved state-of-the-art results in the lexical substitution task by relying on contextual information extracted from the replaced word within the sentence. However, such models do not take into account...
Preprint
Full-text available
The COVID-19 pandemic has had devastating effects on the well-being of the global population. The pandemic has been so prominent partly due to the high infection rate of the virus and its variants. In response, one of the most effective ways to stop infection is rapid diagnosis. The main-stream screening method, reverse transcription-polymerase cha...
Preprint
Full-text available
As the "Mobile AI" revolution continues to grow, so does the need to understand the behaviour of edge-deployed deep neural networks. In particular, MobileNets are the go-to family of deep convolutional neural networks (CNN) for mobile. However, they often have significant accuracy degradation under post-training quantization. While studies have int...
Preprint
Full-text available
In this work, an automatic and simple framework for hockey ice-rink localization from broadcast videos is introduced. First, video is broken into video-shots by a hierarchical partitioning of the video frames, and thresholding based on their histograms. To localize the frames on the ice-rink model, a ResNet18-based regressor is implemented and trai...
Article
COVID-19 pandemic has drastically changed our lives. Chest radiographyhas been used to detect COVID-19. However, the numberof publicly available COVID-19 x-ray images is extremely limited,resulting in a highly imbalanced dataset. This is a challenge whenusing deep learning for classification and detection. In this work, wepropose the use of pre-tra...
Article
With the proliferation of deep convolutional neural network (CNN) algorithms for mobile processing, limited precision quantization has become an essential tool for CNN efficiency. Consequently, various works have sought to design fixed precision quantization algorithms and quantization-focused optimization techniques that minimize quantization indu...
Article
Multi-scale image decomposition (MID) is a fundamental task in computer vision and image processing that involves the transformation of an image into a hierarchical representation comprising of different levels of visual granularity from coarse structures to fine details. A well-engineered MID disentangles the image signal into meaningful component...
Preprint
Full-text available
With the proliferation of deep convolutional neural network (CNN) algorithms for mobile processing, limited precision quantization has become an essential tool for CNN efficiency. Consequently, various works have sought to design fixed precision quantization algorithms and quantization-focused optimization techniques that minimize quantization indu...
Preprint
Full-text available
Depth factorization and quantization have emerged as two of the principal strategies for designing efficient deep convolutional neural network (CNN) architectures tailored for low-power inference on the edge. However, there is still little detailed understanding of how different depth factorization choices affect the final, trained distributions of...
Chapter
Image quality is of utmost importance for image-based clinical diagnosis. In this paper, a generative adversarial network-based retinal fundus quality enhancement network is proposed. With the advent of different cheaper, affordable and lighter point-of-care imaging or telemedicine devices, the chances of making a better and more accessible healthc...
Article
Full-text available
The outbreak of the novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been continuously affecting human lives and communities around the world in many ways, from cities under lockdown to new social experiences. Although in most cases COVID-19 results in mild illness, it has dra...
Article
Full-text available
Advance knowledge of soil water content (SWC) in the soil wetting layer of crop irrigation can help develop more reasonable irrigation plans and improve the efficiency of agricultural irrigation water use. To improve the accuracy of predicting SWC at multiple depths, the ResBiLSTM model was proposed, in which continuous meteorological and SWC data...
Conference Paper
Full-text available
In neuroscience, a tuning dimension is a stimulus attribute that accounts for much of the activation variance of a group of neurons. These are commonly used to decipher the responses of such groups. While researchers have attempted to manually identify an analogue to these tuning dimensions in deep neural networks, we are unaware of an automatic wa...
Preprint
Full-text available
In neuroscience, a tuning dimension is a stimulus attribute that accounts for much of the activation variance of a group of neurons. These are commonly used to decipher the responses of such groups. While researchers have attempted to manually identify an analogue to these tuning dimensions in deep neural networks, we are unaware of an automatic wa...
Preprint
The ability to interpret social cues comes naturally for most people, but for those living with Autism Spectrum Disorder (ASD), some experience a deficiency in this area. This paper presents the development of a multimodal augmented reality (AR) system which combines the use of computer vision and deep convolutional neural networks (CNN) in order t...
Preprint
Full-text available
In most clinical practice settings, there is no rigorous reviewing of the clinical documentation, resulting in inaccurate information captured in the patient medical records. The gold standard in clinical data capturing is achieved via "expert-review", where clinicians can have a dialogue with a domain expert (reviewers) and ask them questions abou...
Preprint
Prior studies have unveiled the vulnerability of the deep neural networks in the context of adversarial machine learning, leading to great recent attention into this area. One interesting question that has yet to be fully explored is the bias-variance relationship of adversarial machine learning, which can potentially provide deeper insights into t...
Preprint
The outbreak of the novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been continuously affecting human lives and communities around the world in many ways, from cities under lockdown to new social experiences. Although in most cases COVID-19 results in mild illness, it has dra...
Preprint
Building footprint extraction in remote sensing data benefits many important applications, such as urban planning and population estimation. Recently, rapid development of Convolutional Neural Networks (CNNs) and open-sourced high resolution satellite building image datasets have pushed the performance boundary further for automated building extrac...
Preprint
While recent advances in deep learning have led to significant improvements in facial expression classification (FEC), a major challenge that remains a bottleneck for the widespread deployment of such systems is their high architectural and computational complexities. This is especially challenging given the operational requirements of various FEC...
Article
Full-text available
Studies have shown that mental health and comorbidities such as dementia, diabetes and cardiovascular diseases are risk factors for dialysis patients. Extracting accurate and timely information associated with these risk factors in the patient health records is not only important for dialysis patient management, but also for real-world evidence gen...
Conference Paper
Full-text available
Studies have been shown that mental health and comorbidities such as dementia, diabetes and cardiovascular diseases are risk factors for dialysis patients. Extracting accurate and timely information associated with these risk factors in patient health records is not only important for dialysis patient management, but also for real world evidence ge...
Preprint
The COVID-19 pandemic continues to have a devastating effect on the health and well-being of the global population. A critical step in the fight against COVID-19 is effective screening of infected patients, with one of the key screening approaches being radiological imaging using chest radiography. Motivated by this, a number of artificial intellig...
Preprint
A core challenge faced by the majority of individuals with Autism Spectrum Disorder (ASD) is an impaired ability to infer other people's emotions based on their facial expressions. With significant recent advances in machine learning, one potential approach to leveraging technology to assist such individuals to better recognize facial expressions a...
Article
Although accurate training and initialization information is difficult to acquire, unsupervised hyperspectral subpixel mapping (SPM) without relying on this predefined information is an insufficiently addressed research issue. This letter presents a novel Bayesian approach for unsupervised SPM of hyperspectral imagery (HSI) based on the Markov rand...
Conference Paper
Full-text available
Machine learning techniques have demonstrated successful applications in identifying risk factors and detecting diseases. Predictive models enable healthcare providers to optimize the allocation of healthcare resources and achieve better outcomes. However, understanding, validating, and thus trusting the decision-making process made by a machine le...
Preprint
Computer vision based technology is becoming ubiquitous in society. One application area that has seen an increase in computer vision is assistive technologies, specifically for those with visual impairment. Research has shown the ability of computer vision models to achieve tasks such provide scene captions, detect objects and recognize faces. Alt...
Preprint
Recent improvements in object detection have shown potential to aid in tasks where previous solutions were not able to achieve. A particular area is assistive devices for individuals with visual impairment. While state-of-the-art deep neural networks have been shown to achieve superior object detection performance, their high computational and memo...
Preprint
Full-text available
In this study, we propose the Affine Variational Autoencoder (AVAE), a variant of Variational Autoencoder (VAE) designed to improve robustness by overcoming the inability of VAEs to generalize to distributional shifts in the form of affine perturbations. By optimizing an affine transform to maximize ELBO, the proposed AVAE transforms an input to th...
Preprint
Full-text available
In this study, we propose the leveraging of interpretability for tasks beyond purely the purpose of explainability. In particular, this study puts forward a novel strategy for leveraging gradient-based interpretability in the realm of adversarial examples, where we use insights gained to aid adversarial learning. More specifically, we introduce the...
Article
Full-text available
In this study, we explore the training of monolithic deep neural net-works in an effective manner. One of the biggest challenges withtraining such networks to the desired level of accuracy is the dif-ficulty in converging to a good solution using iterative optimizationmethods such as stochastic gradient descent due to the enormousnumber of paramete...
Article
Full-text available
Neural network models have shown state of the art performance inseveral applications. However it has been observed that they aresusceptible to adversarial attacks: small perturbations to the inputthat fool a network model into mislabelling the input data. Theseattacks can also transfer from one network model to another, whichraises concerns over th...
Article
Speed limit violation by vehicles is one of the most frequent reasons for road crashes, which take the lives of many people every year, resulting in an increasing demand for video-based vehicle speed estimation systems. One of the biggest challenges to achieve monocular video-based vehicle speed estimation is the projection displacement difference...
Preprint
Full-text available
While microscopic analysis of histopathological slides is generally considered as the gold standard method for performing cancer diagnosis and grading, the current method for analysis is extremely time consuming and labour intensive as it requires pathologists to visually inspect tissue samples in a detailed fashion for the presence of cancer. As s...
Preprint
Much of the focus in the design of deep neural networks has been on improving accuracy, leading to more powerful yet highly complex network architectures that are difficult to deploy in practical scenarios, particularly on edge devices such as mobile and other consumer devices, given their high computational and memory requirements. As a result, th...

Citations

... In this work, we separate synonyms from both acronyms and abbreviations due to their importance in medical domain (Yu et al., 2002). While synonymous relations could be implicitly learned from pretrained language model (LM) (Michalopoulos et al., 2022;Li et al., 2022), previous researches show that language models are only limited to biomedical (Sung et al., 2021) or clinical knowledge bases (Yao et al., 2022) due to the data sparsity challenge in the medical domain. An explicit way of adding such medical knowledge into language model should be explored. ...
... Table 2 shows the results for the ranking task on SemEval-07 and SWORDS. Michalopoulos et al. (2022) harness WordNet (Fellbaum, 1998) to obtain synsets of the target word and also their glosses, and employ BERT and RoBERTa (Liu et al., 2019) to rank candidates. The models proposed by Lacerra et al. (2021a) are different from the others in that they fine-tune BERT on lexical substitution data sets. ...
... There exists an accumulation effect of quantization error in quantization [37], which is manifested by the increasing tendency of quantization error in the network influenced by the quantization of previous layers. Since PTQ does not contain quantization training, this accumulation effect is more obvious in reconstruction loss. ...
... UmlsBERT (Michalopoulos et al., 2021) also integrates external knowledge resources to improve biomedical language models. The authors updated the masked language modeling in the pre-training step with the associations between the words specified in the UMLS. ...
... Although a geometry-guided postprocessing approach based on accurate edges could lead to an effective and fast building polygon reconstruction, it has not been fully explored. Most recent deep learning based approaches tend to ignore this explicit knowledge integration process [3], [7], [16], and thereby cannot efficiently leverage the learned knowledge regarding the prior geometry shape for building outline vectorization. In fact, given accurate building edges with relatively low commission and omission error, a geometry-guided approach can efficiently locate and estimate building corners by leveraging the interaction among adjacent edges and shape prior knowledge learned from building segmentation. ...
... In the fight against the pandemic, computer-aided screening of patients using radiography images has served as a complementary approach to standard polymerase chain reaction (PCR) test. Despite our efforts in improving the performance of deep learning models [1,2], a compromise often must be made between the performance and model trust [3]. ...
... Although this review has focused on OCT in a comprehensive manner, there are similar GAN applications in other areas of ophthalmic image analysis including for retinal fundus photography (RF) [77][78][79][80][81][82][83] and OCT angiography (OCTA) . 84 The area of GANs is rapidly evolving and this review aims to provide a window into their wide and increasing level of application to optical coherence tomography. ...
... Deep neural networks have recently been widely used, especially for multi-step prediction. Standard deep neural network (DNN) models, such as convolution neural networks (CNN), long short-term memory (LSTM), gated recurrent units (GRU), encoder-decoder, and transformer models, have been commonly used in computer vision [14], image classification [15], time series prediction [16], natural language processing [17], and other fields. Compared to methods for building PDEs, deep learning demonstrates powerful modeling capabilities with large datasets that can be deployed on modern computer systems. ...
... Existing studies on soil water content simulations in the root zone of crops can be divided into mechanistic models based on the physical laws of water transport and machine learning models based on data characteristics. Machine learning soil moisture prediction methods represented by deep learning models are emerging areas of research [7][8][9]. However, the high cost (data acquisition), computing power (model training), and threshold (model building) required for deep learning limit its application in soil water content (SWC) prediction [10]. ...
... data predefined and formatted to a set structure) healthcare data [143]. While unstructured data present some significant challenges for biomedical informatics, several solutions based on text-mining have been reported [144,145]. Text mining is an AI technology that uses the natural language processing technique to extract facts, relationships, and assertions from unstructured text in documents or databases and transform this type of information into structured data that is suitable for analysis, such as ML models [146]. ...