Pai H. Chou

University of California, Irvine | UCI · Center for Embedded Cyber-Physical Systems (CECS)

This paper presents a family of computational storage drives (CSD) and demonstrates their performance and power improvements due to in-storage processing (ISP) when running big-data analytics applications. CSDs are an emerging class of solid-state drives (SSD) that are capable of running user code while minimizing data-transfer time and energy. App...

A burst-transfer controller utilizing a boost converter for efficient charging of supercapacitors under low supply-power conditions (BurstCap) is presented. Efficient operation is achieved through maximum power transferpoint (MPTP)-based burst-transfer control while mitigating leakage of the reservoir supercapacitor by meansof a two-stage supercapa...

Computational storage drives (CSD) are solid-state drives (SSD) empowered by general-purpose processors that can perform in-storage processing. They have the potential to improve both performance and energy significantly for big-data analytics by bringing compute to data, thereby eliminating costly data transfer while offering better privacy. In th...

Hands-on experience is crucial to truly understanding the principles of operating systems (OS). This paper describes a preemptive, multithreaded embedded OS assigned as a project in a junior-level OS course. It targets the popular 8051 instruction set architecture (ISA) and can run with as little as 128 bytes of RAM and 1 KB of program memory with...

This paper proposes a framework for distributed, in-storage training of neural networks on clusters of computational storage devices. Such devices not only contain hardware accelerators but also eliminate data movement between the host and storage, resulting in both improved performance and power savings. More importantly, this in-storage processin...

The purpose of this study is to analyse the ictal variations in peripheral blood flow using photoplethysmogram (PPG) and single lead Electrocardiogram (ECG) signals. 11 subjects with 56 partial seizures were recorded with the PPG sensor worn on their left ankles. 6 different features from PPG pulse morphology related to hemodynamics were derived. T...

Distributed training is a novel approach to accelerate Deep Neural Networks (DNN) training, but common training libraries fall short of addressing the distributed cases with heterogeneous processors or the cases where the processing nodes get interrupted by other workloads. This paper describes distributed training of DNN on computational storage d...

Objectives: This study examines human Photoplethysmogram (PPG) along with Electrocardiogram (ECG) signals to study cardiac autonomic imbalance in epileptic seizures. The significance and the prevalence of changes in PPG morphological parameters have been investigated to find common patterns among subjects. Alterations in cardiovascular parameters m...

This paper describes EcoMicro, a miniature, self-powered, wireless inertial-sensing node in the volume of 8 x 13 x 9.5 mm3, including energy storage and solar cells. It is smaller than existing systems with similar functionality while retaining rich functionality and efficiency. It is capable of measuring motion using a inertial measurement unit (I...

Objective: Real-time implementation of EEG source localization can be employed in a broad area of applications such as clinical diagnosis of neurologic diseases and brain-computer interface. However, a power-efficient, low-complexity, and real-time implementation of EEG source localization is still challenging due to extensive iterations in the so...

This paper describes a wearable wireless mouse-cursor controller that optically tracks the degree of tilt of the user's head to move the mouse relative distances and therefore the degrees of tilt. The raw data can be processed locally on the wearable device before tirelessly transmitting the mouse-movement reports over Bluetooth Low Energy (BLE) pr...

Two techniques are proposed to alleviate the computational burden of MUltiple SIgnal Classification (MUSIC) algorithm applied to Electroencephalogram (EEG) source localization. A significant reduction was achieved by parsing the cortex surface into smaller regions and nominating only a few regions for the exhaustive search inherent in the MUSIC alg...

The feasibility of using infrared (IR) spectroscopy of the neck muscles in controlling a cursor in a 2-dimensional screen was assessed. The proposed technique utilizes two IR photoplethysmography sensors (λ = 940nm) to monitor the morphological changes of the Scalene and Sternocleidomastoid muscles. Since the reflection of the light has valuable in...

This work presents a collaborative indoor localization system which provides a lightweight location estimation solution for resource constrained IoT devices. The proposed EcoLoc, an encounter-based collaborative indoor localization system, uses the chance of encounter to enable the sharing and composition of multiple trajectories which are generate...

Indoor localization techniques proposed to date have assumed costly resources in terms of computation, power, or sensing modality for many wearable end-devices in the Internet of Things (IoT). To make localization a universal feature for IoT devices, we propose EcoLoc, an indoor localization system using collaborative version of Conditional Random...

Two techniques are proposed to alleviate the computational burden of MUltiple SIgnal Classification (MUSIC) algorithm applied to Electroencephalogram (EEG) source localization. A significant reduction was achieved by parsing the cortex surface into smaller regions and nominating only a few regions for the exhaustive search inherent in the MUSIC alg...

We propose a Bluetooth Low Energy (BLE) beacon that operates entirely on harvested energy from dual ISM-band RF sources with aid from photovoltaics. Indoor RF power can be harvested from Wi-Fi devices in both 2.4 GHz and 5 GHz bands. Indoor photovoltaic power, while often too low to be considered useful, can be used as biasing current to improve th...

Security is important in IoT as any other computing systems. However, standard solutions are necessary but not sufficient due to the added dimensions of their presence in physical space and the possibility for them to interact. This talk presents a new set of challenges on security in IoT systems that compose synergistically. We illustrate the prob...

This paper describes the long-range directional wake-up radio (LDWuR) for wireless mobile networks. In contrast to most wake-up radios (WuR) to date, which are of short range, ours is applicable to long-range deployments. Existing studies achieve long distance by using modulation and coding schemes or by directional antennas, though the latter requ...

A system and method for measuring movements, utilizing one or more wireless accelerometers attached to one or more limbs of a human subject for the purpose of determining certain temporal and spatial gestures of the subject.

We consider the goal of adaptively controlling access to medium in wireless sensor networks with minimal footprint and complexity. Lightweight protocols are desirable in general and inevitable in some real-world applications such as infant monitoring. We assume high-data-rate, resource-constrained wireless sensor nodes in a star network. We take a...

Harvesting energy from the environment is a desirable and increasingly important capability in several emerging applications of smart sensing systems. Due to the low-power characteristics of many smart-sensor systems, their energy harvesting systems (EHS) can achieve high efficiency by emphasizing low overhead in maximum power point tracking (MPPT)...

Incipient motion of coarse gravel-sized sediment was investigated under a range of oscillatory flows. This article examines the relative significance of shear stresses and pressure gradients in triggering motion, which was directly measured with electronic Smart Sediment Grains (SSGs). The data suggest that incipient motion was induced by the press...

This article presents a recursive solution to the power-transmission loss in DC-powered networks. In such a network, the load cannot be modeled as a fixed equivalent resistance value, since the switching regulator may draw more or less current based on the actual supply voltage to meet the power demand. Although the power-transmission loss itself i...

We propose an approach to energy-neutral operation by Wi-Fi beamforming for wearable devices to achieve energyneutral operation. We take advantage of the transmit beamforming feature of IEEE 802.11ac's multiple input, single output (MISO) structure to focus the transmit power to improve the transmission distance and the harvested power level. To an...

We propose an energy-neutral operation by Wi-Fi beamforming for wearable devices. Several studies have been proposed to harvest energy from photovoltaic, thermoelectric, piezoelectric, andWi-Fi sources, but there is still a need for more Wi-Fi harvestable power to achieve energy-neutral operation for low power wearable devices. We take advantage of...

This paper describes EcoBT, one of the first wireless-sensing platforms to support Bluetooth Low Energy (BLE) as their primary communication protocol. EcoBT Super-node is a full-sized node with an on-board digital accelerometer with rich expansion ports, while EcoBT Mini is the miniature version merely 8atimes;8 mm 2 in area. Included on both nodes...

This work presents energy harvesting techniques from low-voltage current used to prevent galvanic corrosion between a metallic structure and a permanent copper/copper sulfate (Cu/CuSO4) reference electrode. Supercapacitors are adopted to compensate for or overcome the limitations of batteries. Then, a boost converter is used to convert the low volt...

The concept of rimware for the integration of IoT (Internet of Things) and the cloud to form a very powerful cyber-physical system is introduced. The specific implementation, called BlueRim, can scale from isolated NoTs to the global IoT. The rimware provides a middleware layer that enables gateway devices to establish connections between the devic...

This demo presents the world's smallest wireless motion-sensing platform based on Bluetooth 4.0 Low Energy (BLE) Technology. It is merely 8 x 8 mm2 in area but is complete with a user-programmable microcontroller and integrated RF, a digital triaxial accelerometer with programmable threshold detection, and a real-time clock and calendar chip, and a...

Greendicator is an indicator system that enables embedded systems to output text to camera-equipped smartphones by blinking an LED. The transmitter emits modulated light pulses using an existing visible-light LED or an IR diode, laser, or light reflector. The receiver uses a camera-equipped smartphone to sense the light pulses and GPU to decode the...

This demo presents the world's smallest wireless motion-sensing platform based on Bluetooth 4.0 Low Energy (BLE) Technology. It is merely 8×8 mm2 in area but is complete with a user-programmable microcontroller and integrated RF, a digital triaxial accelerometer with programmable threshold detection, and a real-time clock and calendar chip, and a m...

Measurements within the mobile bed layer have been limited by previous Eulerian-based technologies. A microelectromechanical system device, called a smart sediment grain (SSG), that can measure and record Lagrangian observations of coastal sediments at incipient motion has been developed. These sensors have the potential to resolve fundamental hypo...

This paper describes a computing backend for a water pipe monitoring system. Today, most such systems are divided into event-triggered and continuous monitoring, but they all lack systematic handling of data. Many systems simply store data in files with specific naming conventions and ad hoc formats, making them difficult to retrieve, maintain, dis...

We propose a new ECG data compression algorithm based on a learned overcomplete dictionary to exploit the correlation between signals in adjacent heart beats. The learned overcomplete dictionary is constructed by K-SVD dictionary learning algorithm, after preprocessing and normalization of length and magnitude. Using the overcomplete dictionary, th...

This paper describes an intelligent insulating shipping container (IISC) and the supporting backend for cold-chain logistics. Each IISC can monitor the interior temperature of the container during shipping of temperature-sensitive items and alerts the deliverer wirelessly via a Bluetooth-Smart (also called Bluetooth 4.0 Low Energy, BLE) connection...

Power-transmission loss can be a severe problem for low-power embedded systems organized in a daisy-chain topology. The loss can be so high that it can result in failure to power the load in the first place. The first contribution of this article is a recursive algorithm for solving the transmission current on each segment of the daisy chain at a g...

Recent advances in low-cost remote monitoring systems have made it possible and practical to perform structural health monitoring (SHM) on a large scale. However, it is difficult for a single remote monitoring system to cover a wide range of SHM applications due to the amount of specialization required. For the remote monitoring system to be flexib...

This paper explores sizing and topology reconfiguration strategies for charging and discharging multiple supercapacitors as energy storage in sub-Watt-scale energy harvesters. To maximize energy efficiency for storage ($eta_{E_{rm storage}}$), total leakage power is kept low by selecting the supercapacitors to charge sequentially, alternately, or i...

In this paper, we propose an estimation algorithm for spatially-variant blur due to camera motion. To estimate the most accurate latent image, we integrated depth sensor (Microsoft Kinect) and IMU sensor with the camera. The joint analysis of the blurry image, IMU data and the depth data provide better recovery of the real camera motion during the...

Measurements of sediment motion have been primarily limited to indirect observations with acoustic and optical instruments. A micro-electro-mechanical systems device that can measure and record Lagrangian observations of coastal sediments at incipient motion has been developed. These sensors move freely, measure acceleration in the six degrees of f...

Contention resolution plays an important role in designing medium access control protocols. Owing to technical constraints of wireless sensor networks, the task of efficiently resolving contention poses several challenges. In clustered wireless sensor networks, many-to-one communication is the dominant pattern, which is also applicable to the star...

This paper proposes using a mosaic image patches composed of the most informative edges found in the original blurry image for the purpose of estimating a motion blur kernel with minimum computational cost. To select these patches we develop a new image analysis tool to efficiently locate informative patches we call the informative-edge map. The co...

This article presents a buffer minimization scheme with low dispatching overhead for embedded software processes. To accomplish this, we exploit behavioral transparency in the model of computation. In such a model (e.g., synchronous dataflow), the state of buffer requirements is determined completely by the firing sequence of the actors without req...

Serial peripheral interface (SPI) has been identified as a bottleneck in many wireless sensing systems today. SPI is used almost universally as the physical connection between the microcontroller unit (MCU) and radios, storage devices, and many types of sensors. Virtually all wireless sensor nodes today perform up to twice as many bus transactions...

This paper proposes a distributed real-time detection algorithm for detecting rupture events in water pipelines noninvasively. The purpose is to suppress not only unnecessary transmission but also local processing in order to save power without sacrificing sensitivity or specificity of the events of interest. All these goals are accomplished by ada...

There is emerging data that patterns of motor activity early in neonatal life can predict impairments in neuromotor development. However, current techniques to monitor infant movement mainly rely on observer scoring, a technique limited by skill, fatigue, and inter-rater reliability. Consequently, we tested the use of a lightweight, wireless, accel...

This paper presents a light-weight hybrid protocol called Bin-MAC (Binary Medium Access Control) for highly resource-constrained wireless sensor nodes. In addition to sim- plicity and low footprint, a distinguishing feature of Bin-MAC is its deterministic contention resolution mechanism, which enables it to achieve bounded latency on data transmiss...

Energy harvesting has been studied as a candidate for powering next generation wireless sensor networks. The technologies that can harvest electric power from ambient energy sources include solar, vibration, heat and wind. However, sensor nodes powered by energy harvesting devices cannot always communicate with other nodes because the energy harves...

EscaCap is an energy harvester that uses a boost-up charge pump to perform maximum power-transfer tracking (MPTT) while charging a reservoir supercapacitor array (RSA) with a reconfigurable topology. Unlike buck-down type harvesters, the voltage-doubling charge pump of EscaCap enables the sensor nodes to operate under low ambient power conditions....

Micro-solar energy harvesting systems have achieved efficient operations through maximum power point tracking (MPPT) and maximum power transfer tracking (MPTT) tech- niques. However, they may have chargers with relatively high power thresholds, below which they have 0% efficiency. As a result, these harvesters either require much larger panels than...

Detecting and reacting to faults is an indispensable capability for many wireless sensor network applications. Unfortunately, implementing fault detection and error correction algorithms is challenging. Programming languages and fault tolerance mechanisms for sensor networks have historically been designed in isolation. This is the first work to co...

Rapidly and accurately estimating the impact of design decisions on performance metrics is critical to both the manual and automated design of wireless sensor networks. Estimating system-level performance metrics such as lifetime, data loss rate, and network connectivity is particularly challenging because they depend on many factors, including net...

Early detection of pipeline damages has been highlighted in water supply industry. Water pressure change in pipeline due to a sudden rupture causes pipe to vibrate and the pressure change propagates through the pipeline. From the measurement of pipe vibration the rupture can be detected. In this paper, the field test results and observations are pr...

This paper discusses issues of using wireless sensor systems to monitor structures and pipelines in the case of disastrous events. The platforms are deployed and monitored remotely on lifetime systems, such as underground water pipelines. Although similar systems have been proposed for monitoring seismic events and the structure health of bridges a...

EcoIMU is a gyro-free, wearable inertial measurement unit (IMU) built with a pair of triaxial accelerometers that are spatially separated and wirelessly connected. It can output the translation and rotation of the body for the purpose of motion tracking and dead reckoning applications. It mitigates error accumulation and drift problems using domain...

EcoCast is an execution framework for macroprogramming of wireless sensor networks. Users access sensor nodes as dynamic objects in Python without being concerned with network protocols or data types. EcoCast extends Python's functional programming primitives map(), reduce(), and filter() to macroprogramming at native speed by patching the firmware...

EcoCast is an execution framework for macroprogramming of wireless sensor networks. Users access sensor nodes as dynamic objects in Python by invoking methods on them without being concerned with network protocols, and type marshalling and demarshalling ensure proper data access. EcoCast extends Python's functional programming primitives map(), red...

Nucleos is a new runtime system for ultra-lightweight embedded systems. Central to Nucleos is a dispatcher based on the concept of recursive threaded code, which enables layers of abstraction from the runtime system and interrupt handlers to application tasks to be composed in a structured, powerful way, all with minimal program code. When used in...

TeleScribe is a software mechanism for efficiently reprogramming embedded systems such as wireless sensor nodes over a shared communication link. One distinguishing feature is its ability to resume update on any node after power failure, link disconnection, or many other indefinite disruptive events. The nodes are guaranteed never to be left in a b...