Razvan C. Bunescu

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47ranked-venue papers
11as first author
12since 2021 · last 2025
0000-0003-2919-3566ORCID · verified

Domains — the database's venue-derived domains; a paper can count in several

Artificial intelligence and machine learning · 25 · 10 first-author · 2 since 2021Systems, architecture and hardware · 12 · 5 since 2021Software engineering, systems software and programming languages · 7 · 2 since 2021Applied, interdisciplinary, general and emerging computing · 5 · 1 first-author · 2 since 2021Databases, data management, data science and information retrieval · 4 · 2 since 2021Graphics, computer vision, multimedia, augmented reality and games · 2Human-computer interaction and ubiquitous computing · 1 · 1 since 2021
YearPublicationVenuePosition
2025 A Text-Based Recommender System that Leverages Explicit Affective State Preferences
abstract
The affective attitude of liking a recommended item reflects just one category in a wide spectrum of affective phenomena that also includes emotions such as entranced or intrigued, moods such as cheerful or buoyant, as well as more fine-grained affective states, such as "pleasantly surprised by the conclusion".In this paper, we introduce a novel recommendation task that can leverage a virtually unbounded range of affective states sought explicitly by the user in order to identify items that, upon consumption, are likely to induce those affective states.Correspondingly, we create a large dataset of user preferences containing expressions of fine-grained affective states that are mined from book reviews, and propose ACRec, a Transformer-based architecture that leverages such affective expressions as input.We then use the resulting dataset of affective states preferences, together with the linked users and their histories of book readings, ratings, and reviews, to train and evaluate multiple recommendation models on the task of matching recommended items with affective preferences.Experimental comparisons with a range of state-of-the-art baselines demonstrate ACRec's superior ability to leverage explicit affective preferences.
Tonmoy Hasan, Razvan C. Bunescu
EMNLP2
2024 Short Story Generation through Autoregressive Transfer of Narrative Continuations
Oseremen O. Uduehi, Razvan C. Bunescu, Laurie Lyda
ICCC2
2024 Can Language Models Employ the Socratic Method? Experiments with Code Debugging
abstract
When employing the Socratic method of teaching, instructors guide students toward solving a problem on their own rather than providing the solution directly. While this strategy can substantially improve learning outcomes, it is usually time-consuming and cognitively demanding. Automated Socratic conversational agents can augment human instruction and provide the necessary scale, however their development is hampered by the lack of suitable data for training and evaluation. In this paper, we introduce a manually created dataset of multi-turn Socratic advice that is aimed at helping a novice programmer fix buggy solutions to simple computational problems. The dataset is then used for benchmarking the Socratic debugging abilities of a number of language models, ranging from fine-tuning the instruction-based text-to-text transformer Flan-T5 to zero-shot and chain of thought prompting of the much larger GPT-4. The code and datasets are made freely available for research at the link below.
Erfan Al-Hossami, Razvan C. Bunescu, Justin Smith 0008, Ryan Teehan
SIGCSE (1)2
2023 Flumen: Dynamic Processing in the Photonic Interconnect
abstract
In chiplet-based heterogeneous architectures, electrical network-on-package (NoP) designs are typically over-provisioned with routers and channels to provide sufficient bandwidth during periods of high network load. Observing that there are significant periods of low/idle network utilization, prior work has proposed modified network-on-chip (NoC) architectures to enable in-network compute, especially for compute-intensive operations (e.g. linear algebra). However, electrical package-level interconnects impose fundamental energy and bandwidth scaling issues for future chiplet architectures.
Kyle Shiflett, Avinash Karanth, Razvan C. Bunescu, Ahmed Louri
ISCA3
2023 Topic-Level Bayesian Surprise and Serendipity for Recommender Systems
abstract
A recommender system that optimizes its recommendations solely to fit a user’s history of ratings for consumed items can create a filter bubble, wherein the user does not get to experience items from novel, unseen categories. One approach to mitigate this undesired behavior is to recommend items with high potential for serendipity, namely surprising items that are likely to be highly rated. In this paper, we propose a content-based formulation of serendipity that is rooted in Bayesian surprise and use it to measure the serendipity of items after they are consumed and rated by the user. When coupled with a collaborative-filtering component that identifies similar users, this enables recommending items with high potential for serendipity. To facilitate the evaluation of topic-level models for surprise and serendipity, we introduce a dataset of book reading histories extracted from Goodreads, containing over 26 thousand users and close to 1.3 million books, where we manually annotate 449 books read by 4 users in terms of their time-dependent, topic-level surprise. Experimental evaluations show that models that use Bayesian surprise correlate much better with the manual annotations of topic-level surprise than distance-based heuristics, and also obtain better serendipitous item recommendation performance.
Tonmoy Hasan, Razvan C. Bunescu
RecSys2
2023 A semantic parsing pipeline for context-dependent question answering over temporally structured data
abstract
We propose a new setting for question answering in which users can query the system using both natural language and direct interactions within a graphical user interface that displays multiple time series associated with an entity of interest. The user interacts with the interface in order to understand the entity's state and behavior, entailing sequences of actions and questions whose answers may depend on previous factual or navigational interactions. We describe a pipeline implementation where spoken questions are first transcribed into text which is then semantically parsed into logical forms that can be used to automatically extract the answer from the underlying database. The speech recognition module is implemented by adapting a pre-trained LSTM-based architecture to the user's speech, whereas for the semantic parsing component we introduce an LSTM-based encoder-decoder architecture that models context dependency through copying mechanisms and multiple levels of attention over inputs and previous outputs. When evaluated separately, with and without data augmentation, both models are shown to substantially outperform several strong baselines. Furthermore, the full pipeline evaluation shows only a small degradation in semantic parsing accuracy, demonstrating that the semantic parser is robust to mistakes in the speech recognition output. The new question answering paradigm proposed in this paper has the potential to improve the presentation and navigation of the large amounts of sensor data and life events that are generated in many areas of medicine.
Razvan C. Bunescu, Cynthia R. Marling
Nat. Lang. Eng.2
2021 Bitwise Neural Network Acceleration Using Silicon Photonics
abstract
Hardware accelerators provide significant speedup and improve energy efficiency for several demanding deep neural network (DNN) applications. DNNs have several hidden layers that perform concurrent matrix-vector multiplications (MVMs) between the network weights and input features. As MVMs are critical to the performance of DNNs, previous research has optimized the performance and energy efficiency of MVMs at both the architecture and algorithm levels. In this paper, we propose to use emerging silicon photonics technology to improve parallelism, speed and overall efficiency with the goal of providing real-time inference and fast training of neural nets. We use microring resonators (MRRs) and Mach-Zehnder interferometers (MZIs) to design two versions (all-optical and partial-optical) of hybrid matrix multiplications for DNNs. Our results indicate that our partial optical design gave the best performance in both energy efficiency and latency, with a reduction of 33.1% for energy-delay product (EDP) with conservative estimates and a 76.4% reduction for EDP with aggressive estimates.
Kyle Shiflett, Avinash Karanth, Ahmed Louri, Razvan C. Bunescu
ACM Great Lakes Symposium on VLSI4
2021 CSCNN: Algorithm-hardware Co-design for CNN Accelerators using Centrosymmetric Filters
abstract
Convolutional neural networks (CNNs) are at the core of many state-of-the-art deep learning models in computer vision, speech, and text processing. Training and deploying such CNN-based architectures usually require a significant amount of computational resources. Sparsity has emerged as an effective compression approach for reducing the amount of data and computation for CNNs. However, sparsity often results in computational irregularity, which prevents accelerators from fully taking advantage of its benefits for performance and energy improvement. In this paper, we propose CSCNN, an algorithm/hardware co-design framework for CNN compression and acceleration that mitigates the effects of computational irregularity and provides better performance and energy efficiency. On the algorithmic side, CSCNN uses centrosymmetric matrices as convolutional filters. In doing so, it reduces the number of required weights by nearly 50% and enables structured computational reuse without compromising regularity and accuracy. Additionally, complementary pruning techniques are leveraged to further reduce computation by a factor of $2.8-7.2\times $ with a marginal accuracy loss. On the hardware side, we propose a CSCNN accelerator that effectively exploits the structured computational reuse enabled by centrosymmetric filters, and further eliminates zero computations for increased performance and energy efficiency. Compared against a dense accelerator, SCNN and SparTen, the proposed accelerator performs $3.7\times $, $1.6\times $ and $1.3\times $ better, and improves the EDP (Energy Delay Product) by $8.9\times $, $2.8\times $ and $2.0\times $, respectively.
Ahmed Louri, Avinash Karanth, Razvan C. Bunescu
HPCA4
2021 GCNAX: A Flexible and Energy-efficient Accelerator for Graph Convolutional Neural Networks
abstract
Graph convolutional neural networks (GCNs) have emerged as an effective approach to extend deep learning for graph data analytics. Given that graphs are usually irregular, as nodes in a graph may have a varying number of neighbors, processing GCNs efficiently pose a significant challenge on the underlying hardware. Although specialized GCN accelerators have been proposed to deliver better performance over generic processors, prior accelerators not only under-utilize the compute engine, but also impose redundant data accesses that reduce throughput and energy efficiency. Therefore, optimizing the overall flow of data between compute engines and memory, i.e., the GCN dataflow, which maximizes utilization and minimizes data movement is crucial for achieving efficient GCN processing.In this paper, we propose a flexible and optimized dataflow for GCNs that simultaneously improves resource utilization and reduces data movement. This is realized by fully exploring the design space of GCN dataflows and evaluating the number of execution cycles and DRAM accesses through an analysis framework. Unlike prior GCN dataflows, which employ rigid loop orders and loop fusion strategies, the proposed dataflow can reconFigure the loop order and loop fusion strategy to adapt to different GCN configurations, which results in much improved efficiency. We then introduce a novel accelerator architecture called GCNAX, which tailors the compute engine, buffer structure and size based on the proposed dataflow. Evaluated on five real-world graph datasets, our simulation results show that GCNAX reduces DRAM accesses by a factor of $8.1 \times$ and $2.4 \times$, while achieving $8.9 \times, 1.6 \times$ speedup and $9.5 \times$, $2.3 \times$ energy savings on average over HyGCN and AWB-GCN, respectively.
Ahmed Louri, Avinash Karanth, Razvan C. Bunescu
HPCA4
2021 Adversarial Learning of Expectation and Surprise: Experiments with Geometric Shapes
Oseremen O. Uduehi, Razvan C. Bunescu
ICCC2
2021 Albireo: Energy-Efficient Acceleration of Convolutional Neural Networks via Silicon Photonics
abstract
With the end of Dennard scaling, highly-parallel and specialized hardware accelerators have been proposed to improve the throughput and energy-efficiency of deep neural network (DNN) models for various applications. However, collective data movement primitives such as multicast and broadcast that are required for multiply-and-accumulate (MAC) computation in DNN models are expensive, and require excessive energy and latency when implemented with electrical networks. This consequently limits the scalability and performance of electronic hardware accelerators. Emerging technology such as silicon photonics can inherently provide efficient implementation of multicast and broadcast operations, making photonics more amenable to exploit parallelism within DNN models. Moreover, when coupled with other unique features such as low energy consumption, high channel capacity with wavelength-division multiplexing (WDM), and high speed, silicon photonics could potentially provide a viable technology for scaling DNN acceleration.In this paper, we propose Albireo, an analog photonic architecture for scaling DNN acceleration. By characterizing photonic devices such as microring resonators (MRRs) and Mach-Zehnder modulators (MZM) using photonic simulators, we develop realistic device models and outline their capability for system level acceleration. Using the device models, we develop an efficient broadcast combined with multicast data distribution by leveraging parameter sharing through unique WDM dot product processing. We evaluate the energy and throughput performance of Albireo on DNN models such as ResNet18, MobileNet and VGG16. When compared to cur-rent state-of-the-art electronic accelerators, Albireo increases throughput by 110 X, and improves energy-delay product (EDP) by an average of 74 X with current photonic devices. Furthermore, by considering moderate and aggressive photonic scaling, the proposed Albireo design shows that EDP can be reduced by at least 229 X.
Kyle Shiflett, Avinash Karanth, Razvan C. Bunescu, Ahmed Louri
ISCA3
2021 Changing the narrative perspective: From deictic to anaphoric point of view
Razvan C. Bunescu
Inf. Process. Manag.2
2020 Set cover-based methods for motif selection
abstract
MOTIVATION: De novo motif discovery algorithms find statistically over-represented sequence motifs that may function as transcription factor binding sites. Current methods often report large numbers of motifs, making it difficult to perform further analyses and experimental validation. The motif selection problem seeks to identify a minimal set of putative regulatory motifs that characterize sequences of interest (e.g. ChIP-Seq binding regions). RESULTS: In this study, the motif selection problem is mapped to variants of the set cover problem that are solved via tabu search and by relaxed integer linear programing (RILP). The algorithms are employed to analyze 349 ChIP-Seq experiments from the ENCODE project, yielding a small number of high-quality motifs that represent putative binding sites of primary factors and cofactors. Specifically, when compared with the motifs reported by Kheradpour and Kellis, the set cover-based algorithms produced motif sets covering 35% more peaks for 11 TFs and identified 4 more putative cofactors for 6 TFs. Moreover, a systematic evaluation using nested cross-validation revealed that the RILP algorithm selected fewer motifs and was able to cover 6% more peaks and 3% fewer background regions, which reduced the error rate by 7%. AVAILABILITY AND IMPLEMENTATION: The source code of the algorithms and all the datasets are available at https://github.com/YichaoOU/Set_cover_tools. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.
David W. Juedes, Frank Drews, Razvan C. Bunescu, Lonnie R. Welch
Bioinform.5
2020 Hardware-Level Thread Migration to Reduce On-Chip Data Movement Via Reinforcement Learning
abstract
As the number of processing cores and associated threads in chip multiprocessors (CMPs) continues to scale out, on-chip memory access latency dominates application execution time due to increased data movement. Although tiled CMP architectures with distributed shared caches provide a scalable design, increased physical distance between requesting and responding cores has led to both increased on-chip memory access latency and excess energy consumption. Near data processing is a promising approach that can migrate threads closer to data, however prior hand-engineered rules for fine-grained hardware-level thread migration are either too slow to react to changes in data access patterns, or unable to exploit the large variety of data access patterns. In this article, we propose to use reinforcement learning (RL) to learn relatively complex data access patterns to improve on hardware-level thread migration techniques. By utilizing the recent history of memory access locations as input, each thread learns to recognize the relationship between prior access patterns and future memory access locations. This leads to the unique ability of the proposed technique to make fewer, more effective migrations to intermediate cores that minimize the distance to multiple distinct memory access locations. By allowing a low-overhead RL agent to learn a policy from real interaction with parallel programming benchmarks in a parallel simulator, we show that a migration policy which recognizes more complex data access patterns can be learned. The proposed approach reduces on-chip data movement and energy consumption by an average of 41%, while reducing execution time by 43% when compared to a simple baseline with no thread migration; furthermore, energy consumption and execution time are reduced by an additional 10% when compared to a hand-engineered fine-grained migration policy.
Quintin Fettes, Avinash Karanth, Razvan C. Bunescu, Ahmed Louri, Kyle Shiflett
IEEE Trans. Comput. Aided Des. Integr. Circuits Syst.3
2019 High-performance, Energy-efficient, Fault-tolerant Network-on-Chip Design Using Reinforcement Learnin
abstract
Network-on-Chips (NoCs) are becoming the standard communication fabric for multi-core and system on a chip (SoC) architectures. As technology continues to scale, transistors and wires on the chip are becoming increasingly vulnerable to various fault mechanisms, especially timing errors, resulting in exacerbation of energy efficiency and performance for NoCs. Typical techniques for handling timing errors are reactive in nature, responding to the faults after their occurrence. They rely on error detection/correction techniques which have resulted in excessive power consumption and degraded performance, since the error detection/correction hardware is constantly enabled. On the other hand, indiscriminately disabling error handling hardware can induce more errors and intrusive retransmission traffic. Therefore, the challenge is to balance the trade-offs among error rate, packet retransmission, performance, and energy. In this paper, we propose a proactive fault-tolerant mechanism to optimize energy efficiency and performance with reinforcement learning (RL). First, we propose a new proactive error handling technique comprised of a dynamic scheme for enabling per-router error detection/correction hardware and an effective retransmission mechanism. Second, we propose the use of RL to train the dynamic control policy with the goals of providing increased fault-tolerance, reduced power consumption and improved performance as compared to conventional techniques. Our evaluation indicates that, on average, end-to-end packet latency is lowered by 55%, energy efficiency is improved by 64%, and retransmission caused by faults is reduced by 48% over the reactive error correction techniques.
Ke Wang 0030, Ahmed Louri, Avinash Karanth, Razvan C. Bunescu
DATE4
2019 Learning to Surprise: A Composer-Audience Architecture
Razvan C. Bunescu, Oseremen O. Uduehi
ICCC1
2019 Diagnosing Dysarthria with Long Short-Term Memory Networks
Alex Mayle, Zhiwei Mou, Razvan C. Bunescu, Sadegh Mirshekarian, Chang Liu 0028
INTERSPEECH3
2019 IntelliNoC: a holistic design framework for energy-efficient and reliable on-chip communication for manycores
abstract
As technology scales, Network-on-Chips (NoCs), currently being used for on-chip communication in manycore architectures, face several problems including high network latency, excessive power consumption, and low reliability. Simultaneously addressing these problems is proving to be difficult due to the explosion of the design space and the complexity of handling many trade-offs. In this paper, we propose IntelliNoC, an intelligent NoC design framework which introduces architectural innovations and uses reinforcement learning to manage the design complexity and simultaneously optimize performance, energy-efficiency, and reliability in a holistic manner. IntelliNoC integrates three NoC architectural techniques: (1) multifunction adaptive channels (MFACs) to improve energy-efficiency; (2) adaptive error detection/correction and re-transmission control to enhance reliability; and (3) a stress-relaxing bypass feature which dynamically powers off NoC components to prevent overheating and fatigue. To handle the complex dynamic interactions induced by these techniques, we train a dynamic control policy using Q-learning, with the goal of providing improved fault-tolerance and performance while reducing power consumption and area overhead. Simulation using PARSEC benchmarks shows that our proposed IntelliNoC design improves energy-efficiency by 67% and mean-time-to-failure (MTTF) by 77%, and decreases end-to-end packet latency by 32% and area requirements by 25% over baseline NoC architecture.
Ke Wang 0030, Ahmed Louri, Avinash Karanth, Razvan C. Bunescu
ISCA4
2019 Dynamic Voltage and Frequency Scaling in NoCs with Supervised and Reinforcement Learning Techniques
abstract
Network-on-Chips (NoCs) are the de facto choice for designing the interconnect fabric in multicore chips due to their regularity, efficiency, simplicity, and scalability. However, NoC suffers from excessive static power and dynamic energy due to transistor leakage current and data movement between the cores and caches. Power consumption issues are only exacerbated by ever decreasing technology sizes. Dynamic Voltage and Frequency Scaling (DVFS) is one technique that seeks to reduce dynamic energy; however this often occurs at the expense of performance. In this paper, we propose LEAD Learning-enabled Energy-Aware Dynamic voltage/frequency scaling for multicore architectures using both supervised learning and reinforcement learning approaches. LEAD groups the router and its outgoing links into the same V/F domain and implements proactive DVFS mode management strategies that rely on offline trained machine learning models in order to provide optimal V/F mode selection between different voltage/frequency pairs. We present three supervised learning versions of LEAD that are based on buffer utilization, change in buffer utilization and change in energy/throughput, which allow proactive mode selection based on accurate prediction of future network parameters. We then describe a reinforcement learning approach to LEAD that optimizes the DVFS mode selection directly, obviating the need for label and threshold engineering. Simulation results using PARSEC and Splash-2 benchmarks on a 4 × 4 concentrated mesh architecture show that by using supervised learning LEAD can achieve an average dynamic energy savings of 15.4 percent for a loss in throughput of 0.8 percent with no significant impact on latency. When reinforcement learning is used, LEAD increases average dynamic energy savings to 20.3 percent at the cost of a 1.5 percent decrease in throughput and a 1.7 percent increase in latency. Overall, the more flexible reinforcement learning approach enables learning an optimal behavior for a wider range of load environments under any desired energy versus throughput tradeoff.
Quintin Fettes, Mark Clark, Razvan C. Bunescu, Avinash Karanth, Ahmed Louri
IEEE Trans. Computers3
2018 Predictive Analysis by Leveraging Temporal User Behavior and User Embeddings
abstract
The rapid growth of mobile devices has resulted in the generation of a large number of user behavior logs that contain latent intentions and user interests. However, exploiting such data in real-world applications is still difficult for service providers due to the complexities of user behavior over a sheer number of possible actions that can vary according to time. In this work, a time-aware RNN model, TRNN, is proposed for predictive analysis from user behavior data. First, our approach predicts next user action more accurately than the baselines including the n-gram models as well as two recently introduced time-aware RNN approaches. Second, we use TRNN to learn user embeddings from sequences of user actions and show that overall the TRNN embeddings outperform conventional RNN embeddings. Similar to how word embeddings benefit a wide range of task in natural language processing, the learned user embeddings are general and could be used in a variety of tasks in the digital marketing area. This claim is supported empirically by evaluating their utility in user conversion prediction, and preferred application prediction. According to the evaluation results, TRNN embeddings perform better than the baselines including Bag of Words (BoW), TFIDF and Doc2Vec. We believe that TRNN embeddings provide an effective representation for solving practical tasks such as recommendation, user segmentation and predictive analysis of business metrics.
Sungchul Kim, Ryan Rossi, Eunyee Koh, Branislav Kveton, Razvan C. Bunescu
CIKM7
2018 LEAD: learning-enabled energy-aware dynamic voltage/frequency scaling in NoCs
abstract
Network on Chips (NoCs) are the interconnect fabric of choice for multicore processors due to their superiority over traditional buses and crossbars in terms of scalability. While NoC's offer several advantages, they still suffer from high static and dynamic power consumption. Dynamic Voltage and Frequency Scaling (DVFS) is a popular technique that allows dynamic energy to be saved, but it can potentially lead to loss in throughput. In this paper, we propose LEAD - Learning-enabled Energy-Aware Dynamic voltage/frequency scaling for NoC architectures wherein we use machine learning techniques to enable energy-performance trade-offs at reduced overhead cost. LEAD enables a proactive energy management strategy that relies on an offline trained regression model and provides a wide variety of voltage/frequency pairs (modes). LEAD groups each router and the router's outgoing links locally into the same V/F domain, allowing energy management at a finer granularity without additional timing complications and overhead. Our simulation results using PARSEC and Splash-2 benchmarks on a 4 × 4 concentrated mesh architecture show an average dynamic energy savings of 17% with a minimal loss of 4% in throughput and no latency increase.
Mark Clark, Avinash Karanth, Razvan C. Bunescu, Ahmed Louri
DAC3
2018 Extending the Power-Efficiency and Performance of Photonic Interconnects for Heterogeneous Multicores with Machine Learning
abstract
As communication energy exceeds computation energy in future technologies, traditional on-chip electrical interconnects face fundamental challenges in the many-core era. Photonic interconnects have been proposed as a disruptive technology solution due to superior performance per Watt, distance independent energy consumption and CMOS compatibility for on-chip interconnects. Static power due to the laser being always switched on, varying link utilization due to spatial and temporal traffic fluctuations and thermal sensitivity are some of the critical challenges facing photonics interconnects. In this paper, we propose photonic interconnects for heterogeneous multicores using a checkerboard pattern that clusters CPU-GPU cores together and implements bandwidth reconfiguration using local router information without global coordination. To reduce the static power, we also propose a dynamic laser scaling technique that predicts the power level for the next epoch using the buffer occupancy of previous epoch. To further improve power-performance trade-offs, we also propose a regression-based machine learning technique for scaling the power of the photonic link. Our simulation results demonstrate a 34% performance improvement over a baseline electrical CMESH while consuming 25% less energy per bit when dynamically reallocating bandwidth. When dynamically scaling laser power, our buffer-based reactive and ML-based proactive prediction techniques show 40 - 65% in power savings with 0 - 14% in throughput loss depending on the reservation window size.
Scott Van Winkle, Avinash Karanth, Razvan C. Bunescu, Ahmed Louri
HPCA3
2018 Bug Report Classification Using LSTM Architecture for More Accurate Software Defect Locating
abstract
Recently many information retrieval (IR)-based approaches have been proposed to help locate software defects automatically by using information from bug report contents. However, some bug reports that do not semantically related to the relevant code are not helpful to IR-based systems. Running an IR-based system on these reports may produce false positives. In this paper, we propose a classification model for classifying a bug report as either helpful or unhelpful using a LSTM-network. By filtering our unhelpful reports before running an IR-based bug locating system, our approach helps reduce false positives and improve the ranking performance. We test our model over 9,000 bug reports from three software projects. The evaluation result shows that our model helps improve a state-of-the-art IR-based system's ranking performance under a trade-off between the precision and the recall. Our comparison experiments show that the LSTM-network achieves the best trade-off between precision and recall than other classification models including CNN, multilayer perceptron, and a simple baseline approach that classifies a bug report based its length. In the situation that precision is more important than recall, our classification model helps for bug locating.
Xin Ye 0003, Fan Fang, John Wu, Razvan C. Bunescu, Chang Liu 0028
ICMLA4
2017 Recognition of Dynamic Hand Gestures from 3D Motion Data Using LSTM and CNN Architectures
abstract
Hand gestures provide a natural, non-verbal form of communication that can augment or replace other communication modalities such as speech or writing. Along with voice commands, hand gestures are becoming the primary means of interaction in games, augmented reality, and virtual reality platforms. Recognition accuracy, flexibility, and computational cost are some of the primary factors that can impact the incorporation of hand gestures in these new technologies, as well as their subsequent retrieval from multimodal corpora. In this paper, we present fast and highly accurate gesture recognition systems based on long short-term memory (LSTM) and convolutional neural networks (CNN) that are trained to process input sequences of 3D hand positions and velocities acquired from infrared sensors. When evaluated on real time recognition of six types of hand gestures, the proposed architectures obtain 97% F-measure, demonstrating a significant potential for practical applications in novel human-computer interfaces.
Chinmaya R. Naguri, Razvan C. Bunescu
ICMLA2
2016 From word embeddings to document similarities for improved information retrieval in software engineering
abstract
The application of information retrieval techniques to search tasks in software engineering is made difficult by the lexical gap between search queries, usually expressed in natural language (e.g. English), and retrieved documents, usually expressed in code (e.g. programming languages). This is often the case in bug and feature location, community question answering, or more generally the communication between technical personnel and non-technical stake holders in a software project. In this paper, we propose bridging the lexical gap by projecting natural language statements and code snippets as meaning vectors in a shared representation space. In the proposed architecture, word embeddings are first trained on API documents, tutorials, and reference documents, and then aggregated in order to estimate semantic similarities between documents. Empirical evaluations show that the learned vector space embeddings lead to improvements in a previously explored bug localization task and a newly defined task of linking API documents to computer programming questions.
Xin Ye 0003, Razvan C. Bunescu, Chang Liu 0028
ICSE4
2016 Tone Classification in Mandarin Chinese Using Convolutional Neural Networks
Razvan C. Bunescu, Chang Liu 0028
INTERSPEECH2
2016 Mapping Bug Reports to Relevant Files: A Ranking Model, a Fine-Grained Benchmark, and Feature Evaluation
abstract
When a new bug report is received, developers usually need to reproduce the bug and perform code reviews to find the cause, a process that can be tedious and time consuming. A tool for ranking all the source files with respect to how likely they are to contain the cause of the bug would enable developers to narrow down their search and improve productivity. This paper introduces an adaptive ranking approach that leverages project knowledge through functional decomposition of source code, API descriptions of library components, the bug-fixing history, the code change history, and the file dependency graph. Given a bug report, the ranking score of each source file is computed as a weighted combination of an array of features, where the weights are trained automatically on previously solved bug reports using a learning-to-rank technique. We evaluate the ranking system on six large scale open source Java projects, using the before-fix version of the project for every bug report. The experimental results show that the learning-to-rank approach outperforms three recent state-of-the-art methods. In particular, our method makes correct recommendations within the top 10 ranked source files for over 70 percent of the bug reports in the Eclipse Platform and Tomcat projects.
Xin Ye 0003, Razvan C. Bunescu, Chang Liu 0028
IEEE Trans. Software Eng.2
2015 Resilient and Power-Efficient Multi-Function Channel Buffers in Network-on-Chip Architectures
abstract
Network-on-Chips (NoCs) are quickly becoming the standard communication paradigm for the growing number of cores on the chip. While NoCs can deliver sufficient bandwidth and enhance scalability, NoCs suffer from high power consumption due to the router microarchitecture and communication channels that facilitate inter-core communication. As technology keeps scaling down in the nanometer regime, unpredictable device behavior due to aging, infant mortality, design defects, soft errors, aggressive design, and process-voltage-temperature variations, will increase and will result in a significant increase in faults (both permanent and transient) and hardware failures. In this paper, we propose QORE-a fault tolerant NoC architecture with Multi-Function Channel (MFC) buffers. The use of MFC buffers and their associated control (link and fault controllers) enhance fault-tolerance by allowing the NoC to dynamically adapt to faults at the link level and reverse propagation direction to avoid faulty links. Additionally, MFC buffers reduce router power and improve performance by eliminating in-router buffering. We utilize a machine learning technique in our link controllers to predict the direction of traffic flow in order to more efficiently reverse links. Our simulation results using real benchmarks and synthetic traffic mixes show that QORE improves speedup by 1.3x and throughput by 2.3x when compared to state-of-the art fault tolerant NoCs designs such as Ariadne and Vicis. Moreover, using Synopsys Design Compiler, we also show that network power in QORE is reduced by 21 percent with minimal control overhead.
Dominic DiTomaso, Avinash Karanth, Ahmed Louri, Razvan C. Bunescu
IEEE Trans. Computers4
2014 Learning to rank relevant files for bug reports using domain knowledge
abstract
When a new bug report is received, developers usually need to reproduce the bug and perform code reviews to find the cause, a process that can be tedious and time consuming. A tool for ranking all the source files of a project with respect to how likely they are to contain the cause of the bug would enable developers to narrow down their search and potentially could lead to a substantial increase in productivity. This paper introduces an adaptive ranking approach that leverages domain knowledge through functional decompositions of source code files into methods, API descriptions of library components used in the code, the bug-fixing history, and the code change history. Given a bug report, the ranking score of each source file is computed as a weighted combination of an array of features encoding domain knowledge, where the weights are trained automatically on previously solved bug reports using a learning-to-rank technique. We evaluated our system on six large scale open source Java projects, using the before-fix version of the project for every bug report. The experimental results show that the newly introduced learning-to-rank approach significantly outperforms two recent state-of-the-art methods in recommending relevant files for bug reports. In particular, our method makes correct recommendations within the top 10 ranked source files for over 70% of the bug reports in the Eclipse Platform and Tomcat projects.
Xin Ye 0003, Razvan C. Bunescu, Chang Liu 0028
SIGSOFT FSE2
2013 Blood Glucose Level Prediction Using Physiological Models and Support Vector Regression
abstract
Patients with diabetes must continually monitor their blood glucose levels and adjust insulin doses, striving to keep blood glucose levels as close to normal as possible. Blood glucose levels that deviate from the normal range can lead to serious short-term and long-term complications. An automatic prediction model that warned people of imminent changes in their blood glucose levels would enable them to take preventive action. Modeling inter-patient differences and the combined effects of insulin and life events on blood glucose have been particularly challenging in the design of accurate blood glucose forecasting systems. In this paper, we describe a solution that uses a generic physiological model of blood glucose dynamics to generate informative features for a Support Vector Regression model that is trained on patient specific data. Experimental results show that the new prediction model outperforms all three diabetes experts involved in the study, thus demonstrating the utility of using the generic physiological features in machine learning models that are individually trained for every patient.
Razvan C. Bunescu, Nigel Struble, Cynthia R. Marling, Jay Shubrook, Frank Schwartz
ICMLA (1)1
2013 Multilingual Word Sense Disambiguation Using Wikipedia
Bharath Dandala, Rada Mihalcea, Razvan C. Bunescu
IJCNLP3
2011 Learning to Grade Short Answer Questions using Semantic Similarity Measures and Dependency Graph Alignments
Michael Mohler, Razvan C. Bunescu, Rada Mihalcea
ACL2
2011 Emerging Applications for Intelligent Diabetes Management
abstract
Diabetes management is a difficult task for patients, who must monitor and control their blood glucose levels in order to avoid serious diabetic complications. It is a difficult task for physicians, who must manually interpret large volumes of blood glucose data to tailor therapy to the needs of each patient. This paper describes three emerging applications that employ AI to ease this task and shares difficulties encountered in transitioning AI technology from university researchers to patients and physicians
Cynthia R. Marling, Matthew Wiley, Razvan C. Bunescu, Jay Shubrook, Frank Schwartz
IAAI3
2011 The 4 Diabetes Support System: A Case Study in CBR Research and Development
Cynthia R. Marling, Matthew Wiley, Tessa Cooper, Razvan C. Bunescu, Jay Shubrook, Frank Schwartz
ICCBR4
2010 A Utility-Driven Approach to Question Ranking in Social QA
Razvan C. Bunescu, Yunfeng Huang
COLING1
2010 Learning the Relative Usefulness of Questions in Community QA
Razvan C. Bunescu, Yunfeng Huang
EMNLP1
2008 Learning with Probabilistic Features for Improved Pipeline Models
Razvan C. Bunescu
EMNLP1
2007 Learning to Extract Relations from the Web using Minimal Supervision
Razvan C. Bunescu, Raymond J. Mooney
ACL1
2007 Multiple instance learning for sparse positive bags
abstract
We present a new approach to multiple instance learning (MIL) that is particularly effective when the positive bags are sparse (i.e. contain few positive instances). Unlike other SVM-based MIL methods, our approach more directly enforces the desired constraint that at least one of the instances in a positive bag is positive. Using both artificial and real-world data, we experimentally demonstrate that our approach achieves greater accuracy than state-of-the-art MIL methods when positive bags are sparse, and performs competitively when they are not. In particular, our approach is the best performing method for image region classification. 1.
Razvan C. Bunescu, Raymond J. Mooney
ICML1
2006 Using Encyclopedic Knowledge for Named entity Disambiguation
Razvan C. Bunescu, Marius Pasca
EACL1
2005 Subsequence Kernels for Relation Extraction
Razvan C. Bunescu, Raymond J. Mooney
NIPS1
2005 Comparative experiments on learning information extractors for proteins and their interactions
Razvan C. Bunescu, Ruifang Ge, Rohit J. Kate, Edward M. Marcotte, Raymond J. Mooney, Arun K. Ramani, Yuk Wah Wong
Artif. Intell. Medicine1
2004 Collective Information Extraction with Relational Markov Networks
abstract
Most information extraction (IE) systems treat separate potential extractions as independent. However, in many cases, considering influences between different potential extractions could improve overall accuracy. Statistical methods based on undirected graphical models, such as conditional random fields (CRFs), have been shown to be an effective approach to learning accurate IE systems. We present a new IE method that employs Relational Markov Networks (a generalization of CRFs), which can represent arbitrary dependencies between extractions. This allows for "collective information extraction" that exploits the mutual influence between possible extractions. Experiments on learning to extract protein names from biomedical text demonstrate the advantages of this approach.
Razvan C. Bunescu, Raymond J. Mooney
ACL1
2003 Sentiment Analyzer: Extracting Sentiments about a Given Topic using Natural Language Processing Techniques
abstract
We present sentiment analyzer (SA) that extracts sentiment (or opinion) about a subject from online text documents. Instead of classifying the sentiment of an entire document about a subject, SA detects all references to the given subject, and determines sentiment in each of the references using natural language processing (NLP) techniques. Our sentiment analysis consists of 1) a topic specific feature term extraction, 2) sentiment extraction, and 3) (subject, sentiment) association by relationship analysis. SA utilizes two linguistic resources for the analysis: the sentiment lexicon and the sentiment pattern database. The performance of the algorithms was verified on online product review articles ("digital camera" and "music" reviews), and more general documents including general Webpages and news articles.
Jeonghee Yi, Tetsuya Nasukawa, Razvan C. Bunescu, Wayne Niblack
ICDM3
2001 The Role of Lexico-Semantic Feedback in Open-Domain Textual Question-Answering
abstract
This paper presents an open-domain textual Question-Answering system that uses several feedback loops to enhance its performance. These feedback loops combine in a new way statistical results with syntactic, semantic or pragmatic information derived from texts and lexical databases. The paper presents the contribution of each feedback loop to the overall performance of 76% human-assessed precise answers.
Sanda M. Harabagiu, Dan I. Moldovan, Marius Pasca, Rada Mihalcea, Mihai Surdeanu, Razvan C. Bunescu, Roxana Girju, Vasile Rus, Paul Morarescu
ACL6
2001 COREFDRAW-A Tool for Annotation and Visualization of Coreference Data
abstract
In Natural Language Processing, coreference resolution involves finding antecedents of referential expressions (e.g. pronouns or some definite nominals). The resolution of coreference depends on a combination of salience, syntactic, semantic and discourse constraints. The acquisition of such knowledge is difficult and could certainly benefit from a visualization tool, enabling the linguist researcher to find examples of coreference relations. Furthermore, an alternative knowledge-minimalist technique for resolving coreference can be developed by relying on text corpora annotated with coreference data. In this paper we present COREFDRAW, a tool that enables both the annotation of coreference data and its visualization from large text corpora. The resulting annotations enable enhanced coreference resolution methods.
Sanda M. Harabagiu, Razvan C. Bunescu, Stefan Trausan-Matu
ICTAI2
2001 Text and Knowledge Mining for Coreference Resolution
Sanda M. Harabagiu, Razvan C. Bunescu, Steven J. Maiorano
NAACL2