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Hamed Farbeh

Publications and source records attributed to Hamed Farbeh.

At least 19 recordsLinked to original sources

From White Canes to Edge AI: A Survey of Assistive Navigation Technologies for Blind and Low-Vision Individuals

Independent mobility is a foundational requirement for the autonomy of blind and low-vision (BLV) individuals, yet the assistive technologies that support it have historically evolved slowly. This survey systematically reviews 108 peer-reviewed studies published between 2008 and 2026, organizing the field into four technological eras: (i) a foundational era of passive mechanical aids, namely the white cane and the guide dog; (ii) a hardware era of electronic travel aids built on ultrasonic, infrared, and satellite positioning sensors that alert users to proximity but lack semantic understanding; (iii) a deep learning era in which convolutional and transformer-based detectors introduced context-aware scene understanding, initially tethered to cloud infrastructure; and (iv) a contemporary edge-native era defined by model compression, quantization, hardware acceleration, and multi-sensor fusion that relocate intelligence onto resource-constrained wearable and mobile devices. For each era we analyze representative systems, sensing modalities, computational architectures, and reported performance, and we consolidate the field's model-optimization techniques into a single technical reference spanning four detector families and twelve compression strategies. Across the corpus, we find a persistent mismatch between rapid algorithmic progress and slow real-world adoption, driven by cognitive overload in user interfaces, fragmented evaluation protocols, and the scarcity of studies involving BLV participants. We conclude with open challenges, including seamless indoor-outdoor transition, standardized benchmarks, privacy-preserving perception, and the emerging role of multimodal foundation models, and outline a roadmap for socially acceptable, user-centered assistive navigation.

cs.HC↗

ROD-Dataset: A Pedestrian-Perspective Benchmark of Urban Obstacle Classes for YOLO-Based Detection

Two groups of pedestrians face avoidable risk on the city sidewalk: people living with visual impairment, who reach an obstacle before anything warns them, and people walking with divided attention, who register a hazard late or not at all. A vision system can warn them only about obstacles it has learned to recognize, so its training data limits the protection it offers. No suitable training set exists: public benchmarks are recorded from vehicles, aerial platforms, or fixed rigs, general-purpose detectors omit the street furniture that causes trips, and pedestrian-focused collections are confined to single regions with incompatible class schemes. This paper introduces the Real-time Obstacle Detection (ROD) dataset: more than 24,000 images and 40,000 annotated obstacles across 25 classes, from vehicles and people to the stairs, manholes, traffic cones, and benches that general-purpose detectors overlook. Because street furniture differs between cities, ROD unifies twenty-nine public collections onto one taxonomy and adds eye-level imagery from two contrasting cities on two continents, Tehran and Toronto. Every label is human-verified, and each capture campaign is admitted only after a compact detector shows it can learn the class. Six lightweight YOLO detectors (nano and tiny variants) benchmarked on ROD all exceed 0.86 recall; YOLO12n attains the highest recall (0.889), YOLO26n the highest precision (0.925), and YOLOv9t the best mAP@0.50 (0.882) with the fewest parameters. Because the recall and mAP rankings disagree, selecting a model by mAP does not minimize missed obstacles, so per-class recall is reported for all 25 classes.

cs.CV↗

Real-Time Obstacle Detection and Distance Estimation on Smartphones for Visually Impaired and Distracted Pedestrians

According to the World Health Organization, at least 2.2 billion people worldwide live with visual impairment, including tens of millions with severe vision loss. Traditional aids such as white canes or guide dogs remain costly, limited in capability, and inaccessible to many. At the same time, smartphone distraction in public spaces has been linked to elevated risks of collisions with vehicles, trips, and falls. These dual challenges motivate lightweight, smartphone-based solutions that combine accessibility with low latency. We present a Kotlin-based Android application that uses a YOLOv8 detector, retrained to recognize eighteen common urban obstacle classes, to deliver real-time obstacle alerts for both user groups. The detector was optimized with pruning, quantization, and early-exit branches, and deployed through the Android Neural Networks API (NNAPI), which can dispatch inference to GPU, NPU, or DSP accelerators when available. On a mid-range smartphone, these optimizations reduced average inference latency from about 3.2 s for the off-the-shelf YOLOv8n to 0.39-0.48 s; the recommended configuration (INT8 quantization with early exit) runs in 0.42-0.48 s while retaining a recall of 0.81. The application combines the optimized detector with ARCore-based or monocular focal-length distance estimation, so it works with a single smartphone camera and requires no LiDAR, depth camera, or other specialized sensor. Multimodal feedback, including Text-to-Speech guidance for visually impaired users and vibration alerts for distracted pedestrians, supports use across different contexts.

cs.CV↗

ReSAFT: An Efficient Stuck-at Fault-Tolerant Scheme for ReRAM-based Process-in-Memory Accelerators

Analog ReRAM-based process-in-memory (PIM) accelerators provide high parallelism and energy efficiency for deep convolutional neural networks (CNNs) inference. However, their susceptibility to permanent faults, such as stuck-at high (SaH) and stuck-at low (SaL) resistance states, poses a major challenge by permanently corrupting the CNN weights mapped to conductance values of ReRAM cells and degrading inference accuracy, which leads to system unreliability in safety-critical applications. In this paper, we propose a fault-tolerant scheme for analog ReRAM-based PIM accelerators to tackle stuck-at faults (SAFs) with minimal redundancy overhead to recover classification accuracy degradation. The proposed scheme contains a redundancy-based hardware solution alongside fault-aware mapping method for ensuring reliable analog computation in ReRAM crossbar. We analyze the impact of varying number of redundant rows and columns on accuracy and design metrics. Subsequently, a multi-objective optimization (MOO) problem is formulated and solved to efficiently determine the number of redundant rows and columns, considering trade-offs among various design metrics. Furthermore, a fault-aware weight mapping is proposed for dual-crossbar structures to further compensate for the accuracy degradation caused by SAFs. Simulation results show that, for the SimpleNet model using the MNIST dataset, the inference accuracy is recovered by approximately 22.39%, on average, across four configurations of optimal solutions, each offering a trade-off between reliability and area, energy consumption, and latency overheads. The mean-time-tofailure (MTTF) improves by about 61x on average compared to the baseline. These selected configurations also reduce energy and area overheads by 32%, on average, in comparison to row-only and column-only configurations.

cs.AR↗

An Empirical Fault Vulnerability Exploration of ReRAM-based Process-in-Memory CNN Accelerators

Resistive random-access memory (ReRAM)-based Processing-in-Memory (PIM) accelerator is a promising platform for processing massively memory intensive matrix-vector multiplications of neural networks in parallel domain, due to its capability of analog computation, ultra-high density, near-zero leakage current, and non-volatility. Despite many advantages, ReRAM-based accelerators are highly error-prone due to limitations of technology fabrication that lead to process variations and defects. These limitations degrade the accuracy of Deep Convolutional Neural Networks (Deep CNNs) running on PIM accelerators. While these CNNs accelerators are widely deployed in safety-critical systems, their vulnerability to fault is not well explored. In this paper, we have developed a fault injection framework to investigate the vulnerability of large-scale CNNs at both software- and hardware-level of inference phases. Faulty ReRAM devices are another reliability challenges due to significant degradation of classification accuracy when CNN parameters are mapped to the accelerators. To investigate this challenge, we map the CNN learning parameter to the ReRAM crossbar and inject faults into crossbar arrays. The proposed framework analyzes the impact of stuck-at high (SaH) and stuck-at low (SaL) fault models on different layers and locations of CNN learning parameters. By performing extensive fault injections, we illustrate that the vulnerability behavior of ReRAM-based PIM accelerator for CNNs is greatly impressible to the types and depth of layers, the location of the learning parameter in every layer, and the value and types of faults. Our observations show that different models have different vulnerabilities to faults. Specifically, we show that SaL further reduces classification accuracy than SaH.

cs.AR↗

Inter-Set Correlation-Aware Replacement Policy for Energy Efficient RTM-based Caches

Today's data-centric applications demand cache architectures that can scale with growing workloads while maintaining high performance and energy efficiency. Fundamental issues such as excessive area consumption and leakage power are increasingly challenging traditional SRAM-based caches, thereby motivating the exploration of non-volatile alternatives. Among these, racetrack memory (RTM) stands out due to its remarkable storage density, achieved through nanowires hosting sequential magnetic domains that can be manipulated via domain wall or skyrmion techniques. Despite its advantages, racetrack memory's inherent serialized access introduces considerable shift overhead, leading to elevated energy consumption and latency. In this paper, we analyze the placement strategies in conventional RTM-based last-level caches and identify that current methods trigger redundant shift operations as a shift intended to read one block fails to preposition other blocks subsequently accessed. To resolve this, we introduce an innovative data placement and replacement scheme that intelligently groups correlated blocks, ensuring that a single shift not only retrieves the target block but also aligns subsequent blocks closer to the access port. Our simulation results using the gem5 simulator and the SPEC CPU2017 benchmarks reveal that our scheme reduces shift overhead by 49.0% and cache energy consumption by 35.9% with negligible performance impact. In addition, this scheme exhibits robust scalability to longer nanowire tracks for higher cache density.

cs.AR↗

Enhancing Reliability of STT-MRAM Caches by Eliminating Read Disturbance Accumulation

Spin-Transfer Torque Magnetic RAM (STT-MRAM) as one of the most promising replacements for SRAMs in on-chip cache memories benefits from higher density and scalability, near-zero leakage power, and non-volatility, but its reliability is threatened by high read disturbance error rate. Error-Correcting Codes (ECCs) are conventionally suggested to overcome the read disturbance errors in STT-MRAM caches. By employing aggressive ECCs and checking out a cache block on every read access, a high level of cache reliability is achieved. However, to minimize the cache access time in modern processors, all blocks in the target cache set are simultaneously read in parallel for tags comparison operation and only the requested block is sent out, if any, after checking its ECC. These extra cache block reads without checking their ECCs until requesting the blocks by the processor cause the accumulation of read disturbance error, which significantly degrade the cache reliability. In this paper, we first introduce and formulate the read disturbance accumulation phenomenon and reveal that this accumulation due to conventional parallel accesses of cache blocks significantly increases the cache error rate. Then, we propose a simple yet effective scheme, so-called Read Error Accumulation Preventer cache (REAP-cache), to completely eliminate the accumulation of read disturbances without compromising the cache performance. Our evaluations show that the proposed REAP-cache extends the cache Mean Time To Failure (MTTF) by 171x, while increases the cache area by less than 1% and energy consumption by only 2.7%.

cs.AR↗

ROBIN: Incremental Oblique Interleaved ECC for Reliability Improvement in STT-MRAM Caches

Spin-Transfer Torque Magnetic RAM} (STT-MRAM) is a promising alternative for SRAMs in on-chip cache memories. Besides all its advantages, high error rate in STT-MRAM is a major limiting factor for on-chip cache memories. In this paper, we first present a comprehensive analysis that reveals that the conventional Error-Correcting Codes (ECCs) lose their efficiency due to data-dependent error patterns, and then propose an efficient ECC configuration, so-called ROBIN, to improve the correction capability. The evaluations show that the inefficiency of conventional ECC increases the cache error rate by an average of 151.7% while ROBIN reduces this value by more than 28.6x.

cs.AR↗

A Low-Cost Reliable Racetrack Cache Based on Data Compression

SRAM-based cache memory faces several scalability limitations in deep nanoscale technologies, e.g., high leakage current, low cell stability, and low density. Emerging Non-Volatile Memory (NVM) technologies have received lots of attention in recent years, where Racetrack Memory (RTM) is among the most promising ones. RTM has the highest density among all NVMs and its access performance is comparable to SRAM technology. Therefore, RTM is a suitable alternative for SRAM in the Last-Level Caches (LLCs). Despite all its benefits, RTM confronts different reliability challenges due to the stochastic behavior of its storage element and highly error-prone data shifting, leading to a high probability of multiple-bit errors. Conventional Error-Correcting Codes (ECCs) are either incapable of tolerating multiple-bit errors or require a large amount of extra storage for check bits. This paper proposes taking advantage of value locality for compressing data blocks and freeing up a large fraction of cache blocks for storing data redundancy of strong ECCs. Utilizing the proposed scheme, a large majority of cache blocks are protected by strong ECCs to tolerate multiple-bit errors without any storage overhead. The evaluation using gem5 full-system simulator demonstrates that the proposed scheme enhances the mean-time-to-failure of the cache by an average of 11.3x with less than 1% hardware and performance overhead.

cs.ET↗

3RSeT: Read Disturbance Rate Reduction in STT-MRAM Caches by Selective Tag Comparison

Recent development in memory technologies has introduced Spin-Transfer Torque Magnetic RAM (STT-MRAM) as the most promising replacement for SRAMs in on-chip cache memories. Besides its lower leakage power, higher density, immunity to radiation-induced particles, and non-volatility, an unintentional bit flip during read operation, referred to as read disturbance error, is a severe reliability challenge in STT-MRAM caches. One major source of read disturbance error in STT-MRAM caches is simultaneous accesses to all tags for parallel comparison operation in a cache set, which has not been addressed in previous work. This paper first demonstrates that high read accesses to tag array extremely increase the read disturbance rate and then proposes a low-cost scheme, so-called Read Disturbance Rate Reduction in STT-MRAM Caches by Selective Tag Comparison (3RSeT), to reduce the error rate by eliminating a significant portion of tag reads. 3RSeT proactively disables the tags that have no chance for hit, using low significant bits of the tags on each access request. Our evaluations using gem5 full-system cycle-accurate simulator show that 3RSeT reduces the read disturbance rate in the tag array by 71.8%, which results in 3.6x improvement in Mean Time To Failure (MTTF). In addition, the energy consumption is reduced by 62.1% without compromising performance and with less than 0.4% area overhead.

cs.AR↗

An Analytical and Empirical Investigation of Tag Partitioning for Energy-Efficient Reliable Cache

Associative cache memory significantly influences processor performance and energy consumption. Because it occupies over half of the chip area, cache memory is highly susceptible to transient and permanent faults, posing reliability challenges. As the only hardware-managed memory module, the cache tag array is the most active and critical component, dominating both energy usage and error rate. Tag partitioning is a widely used technique to reduce tag-access energy and enhance reliability. It divides tag comparison into two phases: first comparing the k lower bits, and then activating only the matching tag entries to compare the remaining higher bits. The key design parameter is the selection of the tag-splitting point k, which determines how many reads are eliminated. However, prior studies have chosen k intuitively, randomly, or empirically, without justification. Even experimentally determined values are ad-hoc and do not generalize across cache configurations due to high sensitivity to architectural parameters. In this paper, we analytically show that choosing k too large or too small substantially reduces the effectiveness of tag partitioning. We then derive a formulation that determines the optimal splitting point based on cache configuration parameters. The formulation is convex, differentiable, and capable of precisely quantifying tag-partitioning efficiency for any k and configuration. To validate our model, we experimentally evaluate tag-partitioning efficiency and optimal k across a broad set of cache designs and demonstrate close agreement between analytical and experimental results. The proposed formulation enables designers and researchers to instantly compute the optimal tag-splitting point and accurately estimate tag-read reduction.

cs.AR↗

A General Solution for the Implementation of CI/CD in Embedded Linux Development

With the growing use of embedded systems in various industries, the need for automated platforms for the development and deployment of customized Linux-based operating systems has become more important. This research was conducted with the aim of designing and implementing an integrated and reproducible infrastructure for the development, building, and testing of a Linux-based operating system using the Yocto Project. The proposed structure was implemented based on a three-layer architecture consisting of the main Yocto repositories, a custom layer (meta-custom), and a coordinating manifest layer to ensure version synchronization, scalability, and reproducibility. Three sample projects, including libhelloworld, helloworld, and the kernel module hello mod, were developed and integrated into the build process. Continuous Integration and Continuous Deployment pipelines were implemented with GitLab CI and combined with an isolated Docker environment to automate and streamline the build and testing workflows. Using a local cache server containing hashserv, downloads and sstate cache significantly reduced the build time. The functionality and stability of the system were verified through six boot test scenarios in the QEMU simulator. The results show that the proposed design not only ensures reproducibility but also can be extended to advanced applications such as continuous deployment of real-time Linux versions. Future recommendations include expanding automated tests, implementing system monitoring with Prometheus and Grafana, using distributed builds, optimizing with Docker multi-stage builds, and enabling continuous deployment of real-time Linux changes to provide a stable and scalable model for industrial and research projects in embedded systems with a rapid and reliable development cycle.

cs.SE↗

AI in Mental Health: Emotional and Sentiment Analysis of Large Language Models' Responses to Depression, Anxiety, and Stress Queries

Depression, anxiety, and stress are widespread mental health concerns that increasingly drive individuals to seek information from Large Language Models (LLMs). This study investigates how eight LLMs (Claude Sonnet, Copilot, Gemini Pro, GPT-4o, GPT-4o mini, Llama, Mixtral, and Perplexity) reply to twenty pragmatic questions about depression, anxiety, and stress when those questions are framed for six user profiles (baseline, woman, man, young, old, and university student). The models generated 2,880 answers, which we scored for sentiment and emotions using state-of-the-art tools. Our analysis revealed that optimism, fear, and sadness dominated the emotional landscape across all outputs, with neutral sentiment maintaining consistently high values. Gratitude, joy, and trust appeared at moderate levels, while emotions such as anger, disgust, and love were rarely expressed. The choice of LLM significantly influenced emotional expression patterns. Mixtral exhibited the highest levels of negative emotions including disapproval, annoyance, and sadness, while Llama demonstrated the most optimistic and joyful responses. The type of mental health condition dramatically shaped emotional responses: anxiety prompts elicited extraordinarily high fear scores (0.974), depression prompts generated elevated sadness (0.686) and the highest negative sentiment, while stress-related queries produced the most optimistic responses (0.755) with elevated joy and trust. In contrast, demographic framing of queries produced only marginal variations in emotional tone. Statistical analyses confirmed significant model-specific and condition-specific differences, while demographic influences remained minimal. These findings highlight the critical importance of model selection in mental health applications, as each LLM exhibits a distinct emotional signature that could significantly impact user experience and outcomes.

cs.CL↗

How Jungian Cognitive Functions Explain MBTI Type Prevalence in Computer Industry Careers

This study investigates the relationship between Carl Jung's cognitive functions and success in computer industry careers by analyzing the distribution of Myers-Briggs Type Indicator (MBTI) types among professionals in the field. Building on Carl Jung's theory of psychological types, which categorizes human cognition into four primary functions, Sensing, Intuition, Thinking, and Feeling, this study investigates how these functions, when combined with the attitudes of Extraversion and Introversion, influence personality types and career choices in the tech sector. Through a comprehensive analysis of data from 30 studies spanning multiple countries and decades, encompassing 18,264 individuals in computer-related professions, we identified the most prevalent cognitive functions and their combinations. After normalizing the data against general population distributions, our findings showed that individual Jungian functions (Te, Ni, Ti, Ne), dual function combinations (Ni-Te, Ti-Ne, Si-Te, Ni-Fe), and MBTI types (INTJ, ENTJ, INTP, ENTP, ISTJ, INFJ, ESTJ, ESTP) had significantly higher representation compared to general population norms. The paper addresses gaps in the existing literature by providing a more nuanced understanding of how cognitive functions impact job performance and team dynamics, offering insights for career guidance, team composition, and professional development in the computer industry, and a deeper understanding of how cognitive preferences influence career success in technology-related fields.

cs.CY↗

PenSLR: Persian end-to-end Sign Language Recognition Using Ensembling

Sign Language Recognition (SLR) is a fast-growing field that aims to fill the communication gaps between the hearing-impaired and people without hearing loss. Existing solutions for Persian Sign Language (PSL) are limited to word-level interpretations, underscoring the need for more advanced and comprehensive solutions. Moreover, previous work on other languages mainly focuses on manipulating the neural network architectures or hardware configurations instead of benefiting from the aggregated results of multiple models. In this paper, we introduce PenSLR, a glove-based sign language system consisting of an Inertial Measurement Unit (IMU) and five flexible sensors powered by a deep learning framework capable of predicting variable-length sequences. We achieve this in an end-to-end manner by leveraging the Connectionist Temporal Classification (CTC) loss function, eliminating the need for segmentation of input signals. To further enhance its capabilities, we propose a novel ensembling technique by leveraging a multiple sequence alignment algorithm known as Star Alignment. Furthermore, we introduce a new PSL dataset, including 16 PSL signs with more than 3000 time-series samples in total. We utilize this dataset to evaluate the performance of our system based on four word-level and sentence-level metrics. Our evaluations show that PenSLR achieves a remarkable word accuracy of 94.58% and 96.70% in subject-independent and subject-dependent setups, respectively. These achievements are attributable to our ensembling algorithm, which not only boosts the word-level performance by 0.51% and 1.32% in the respective scenarios but also yields significant enhancements of 1.46% and 4.00%, respectively, in sentence-level accuracy.

cs.HC↗

Deep Reinforcement Learning for Online Error Detection in Cyber-Physical Systems

Reliability is one of the major design criteria in Cyber-Physical Systems (CPSs). This is because of the existence of some critical applications in CPSs and their failure is catastrophic. Therefore, employing strong error detection and correction mechanisms in CPSs is inevitable. CPSs are composed of a variety of units, including sensors, networks, and microcontrollers. Each of these units is probable to be in a faulty state at any time and the occurred fault can result in erroneous output. The fault may cause the units of CPS to malfunction and eventually crash. Traditional fault-tolerant approaches include redundancy time, hardware, information, and/or software. However, these approaches impose significant overheads besides their low error coverage, which limits their applicability. In addition, the interval between error occurrence and detection is too long in these approaches. In this paper, based on Deep Reinforcement Learning (DRL), a new error detection approach is proposed that not only detects errors with high accuracy but also can perform error detection at the moment due to very low inference time. The proposed approach can categorize different types of errors from normal data and predict whether the system will fail. The evaluation results illustrate that the proposed approach has improved more than 2x in terms of accuracy and more than 5x in terms of inference time compared to other approaches.

cs.LG↗

A Novel Neuromorphic Processors Realization of Spiking Deep Reinforcement Learning for Portfolio Management

The process of continuously reallocating funds into financial assets, aiming to increase the expected return of investment and minimizing the risk, is known as portfolio management. Processing speed and energy consumption of portfolio management have become crucial as the complexity of their real-world applications increasingly involves high-dimensional observation and action spaces and environment uncertainty, which their limited onboard resources cannot offset. Emerging neuromorphic chips inspired by the human brain increase processing speed by up to 1000 times and reduce power consumption by several orders of magnitude. This paper proposes a spiking deep reinforcement learning (SDRL) algorithm that can predict financial markets based on unpredictable environments and achieve the defined portfolio management goal of profitability and risk reduction. This algorithm is optimized forIntel's Loihi neuromorphic processor and provides 186x and 516x energy consumption reduction is observed compared to the competitors, respectively. In addition, a 1.3x and 2.0x speed-up over the high-end processors and GPUs, respectively. The evaluations are performed on cryptocurrency market between 2016 and 2021 the benchmark.

cs.LG↗

TA-LRW: A Replacement Policy for Error Rate Reduction in STT-MRAM Caches

As technology process node scales down, on-chip SRAM caches lose their efficiency because of their low scalability, high leakage power, and increasing rate of soft errors. Among emerging memory technologies, Spin-Transfer Torque Magnetic RAM (STT-MRAM) is known as the most promising replacement for SRAM-based cache memories. The main advantages of STT-MRAM are its non-volatility, near-zero leakage power, higher density, soft-error immunity, and higher scalability. Despite these advantages, the high error rate in STT-MRAM cells due to retention failure, write failure, and read disturbance threatens the reliability of cache memories built upon STT-MRAM technology. The error rate is significantly increased in higher temperatures, which further affects the reliability of STT-MRAM-based cache memories. The major source of heat generation and temperature increase in STT-MRAM cache memories is write operations, which are managed by cache replacement policy. In this paper, we first analyze the cache behavior in the conventional LRU replacement policy and demonstrate that the majority of consecutive write operations (more than 66%) are committed to adjacent cache blocks. These adjacent write operations cause accumulated heat and increased temperature, which significantly increases the cache error rate. To eliminate heat accumulation and the adjacency of consecutive writes, we propose a cache replacement policy, named Thermal-Aware Least-Recently Written (TA-LRW), to smoothly distribute the generated heat by conducting consecutive write operations in distant cache blocks. TA-LRW guarantees the distance of at least three blocks for each two consecutive write operations in an 8-way associative cache. This distant write scheme reduces the temperature-induced error rate by 94.8%, on average, compared with the conventional LRU policy, which results in 6.9x reduction in cache error rate.

cs.AR↗