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Publications (434)
This chapter presents the study on scheduling for cooperative data dissemination in a hybrid I2V and V2V communication environment. We formulate the novel problem of Cooperative Data Scheduling (CDS). Each vehicle informs the RSU the list of its current neighboring vehicles and the identifiers of the retrieved and newly requested data. The RSU then...
The revolution of online shopping in recent years demands corresponding evolution in delivery services in urban areas. To cater to this trend, delivery by the crowd has become an alternative to the traditional delivery services thanks to the advances in ubiquitous computing. Notably, some studies use public transportation for crowdsourcing delivery...
With recent development of wireless communication, sensing and computing technologies, Internet of Vehicles (IoV) has attracted great attention in both academia and industry. Nevertheless, it is challenging to process time-critical tasks due to unique characteristics of IoV, including heterogeneous computation and communication capacities of networ...
The ubiquitous deployment of smart wearable devices brings promises for an effective implementation of various healthcare applications in our everyday living environments. However, given that these applications ask for accurate and reliable sensing results of vital signs, there is a need to understand the accuracy of commercial-off-the-shelf wearab...
Although indoor localization has been studied over a decade, it is still challenging to enable many IoT applications such as activity tracking and monitoring in smart home and customer navigation and trajectory mining in smart shopping mall, which typically require meter-level localization accuracy in a highly dynamic and large scale indoor environ...
With the rapid development of sharing economy, massive sharing systems such as Uber, Airbnb, and bikeshare have percolated into people's daily life. The sharing economy, at its core, is to achieve efficient use of resources. The actual usage of shared resources, however, is unclear to us. Little measurement or analysis, if any, has been conducted t...
Under a stochastic roadway, drivers need a route guidance system incorporating travel time variability. To recommend a customized path depending on the trip purpose and the driver’s risk-taking behavior, various path ranking methods have been developed. Unlike those methods, our proposed disutility method can easily incorporate a target arrival tim...
With the exponential improvement of software technology during the past decade, many efforts have been made to design remote and personalized healthcare applications. Many of these applications are built on mobile devices connected to the cloud. Although appealing, however, prototyping and validating the feasibility of an application-level idea is...
Bike sharing systems, which provide a convenient commute choice for short trips, have emerged rapidly in many cities. While bike sharing has greatly facilitated people's commutes, those systems are facing a costly maintenance issue -- rebalancing bikes among stations. We observe that existing systems frequently suffer situations such as no-bike-to-...
Temporal information services are critical in implementing emerging intelligent transportation systems. Nevertheless, it is challenging to realize timely temporal data update and dissemination due to an intermittent wireless connection and a limited communication bandwidth in dynamic vehicular networks. Some previous studies have considered the tem...
Abstract—Efficient data dissemination is critical for enabling emerging applications in vehicular ad-hoc networks (VANETs). As a typical traffic scenario, the bidirectional road scenario of highways bring unique challenges on well exploiting the benefit of vehicle-to-vehicle (V2V) communication for data sharing among vehicles driving in opposite di...
This work aims at proposing a transfer learning (TL) based framework to enhance system scalability of fingerprint-based indoor localization by reducing offline training overhead without jeopardizing the localization accuracy. The basic principle is to reshape data distributions in the target domain based on the transferred knowledge from the source...
In this paper, we propose a spatio-temporal coordination-based media access control (STMAC) protocol for efficiently sharing driving safety information in urban vehicular networks. STMAC exploits a unique spatio-temporal feature characterized from a geometric relation among vehicles to form a line-of-collision graph, which shows the relationship am...
With the advancement of technology in various domains, many efforts have been made to design advanced classification engines that aid the protection of civilians and their properties in different settings. In this work, we focus on a set of the population which is probably the most vulnerable: children. Specifically, we present ChildSafe, a classif...
Recent research showed that human mobility is characterized by reproducible patterns, i.e., humans tend to travel a few known places. Timely identification of these “significant journeys” has prospects for emerging intelligent applications like real-time traffic route recommendation and automated HVAC systems. Existing mobile systems, however, util...
With the wide-distribution of smart wearables, it seems as though ubiquitous healthcare can finally permeate into our everyday lives, opening the possibility to realize clinical-grade applications. However, given that clinical applications require reliable sensing, there is a need to understand how accurate healthcare sensors on wearable devices (e...
We present WiTraffic: the first WiFi-based traffic monitoring system. The unique WiFi Channel State Information (CSI) patterns of passing vehicles are captured and analyzed to perform vehicle classification. We implemented WiTraffic with off-the-shelf WiFi devices and performed real-world experiments with over a week of field data collection. The r...
Smart watches are increasingly being used in various applications to monitor heart rate for exercise and health care purposes. It is crucial that the readings from these devices are accurate so that users can take proper actions according to the intensity of the heart rate. Taking actions from inaccurate readings can negatively impact the health of...
Diaries are used to record aspects of lives --- activities, events, experiences, feelings, thoughts, and physiological measures. Smart diaries can reduce the user's burden by automatically registering some of these aspects. Existing systems have two weaknesses: (a) they are not extensible, and (b) their design is not theory-driven. We introduce Lif...
Data-driven modeling usually suffers from data sparsity, especially for large-scale modeling for urban phenomena based on single-source urban-infrastructure data under fine-grained spatial-temporal contexts. To address this challenge, we motivate, design, and implement UrbanCPS, a cyber-physical system with heterogeneous model integration, based on...
Human mobility is known to follow simple reproducible patterns, i.e., humans tend to travel a few known
places. Early detection of those “significant journeys” has a prospect for emerging smart applications like real-time traffic route recommendation and automated HVAC (heating, ventilating, and air conditioning) systems. In this paper, we design,...
Vehicular networks represent a research area of significant importance in improving the safety, efficiency and sustainability of transportation systems. One of the key research problems in vehicular networks is real-time data dissemination, which is crucial to the satisfactory performance of many emergent applications providing real-time informatio...
Traffic jams often occur without any obvious reasons such as traffic accidents, roadwork, or closed lanes. Under moderate to high traffic density, minor perturbations to traffic flow (e.g., a strong braking motion) are easily amplified into a wave of stop-and-go traffic. This is known as a phantom jam. In this paper, we aim to mitigate phantom jams...
Fatal accidents occur frequently on low-volume rural roads, and the accident rates are up to 4 times higher at curves. It is thus of paramount importance to perform road inventory of rural roads to develop safety plans. However, most states in U.S. face a challenge to maintain a database for low volume rural roads due to limited funds for road inve...
Many efforts have been made to design classification systems that can aid the protection of elderly in a home environment. In this work, we focus on an accident that is a great risk for seniors living alone, a fall. Specifically, we present FADES, which uses skeletal joint information collected from a 3D depth camera to accurately classify differen...
Efficient data sharing in vehicular ad hoc networks (VANETs) is one of the fundamental requirements to enable emerging intelligent transportation systems. Much research has focused on the routing algorithms and MAC protocols in VANETs. However, unique characteristics of data sharing for bidirectional road scenarios make it challenging to design an...
This paper presents the first study on scheduling for cooperative data dissemination in a hybrid infrastructure-to-vehicle (I2V) and vehicle-to-vehicle (V2V) communication environment. We formulate the novel problem of cooperative data scheduling (CDS). Each vehicle informs the road-side unit (RSU) the list of its current neighboring vehicles and t...
In smart environments, target tracking is an essential service used by numerous applications from activity recognition to personalized infotaintment. The target tracking relies on sensors with known locations to estimate and keep track of the path taken by the target, and hence, it is crucial to have an accurate map of such sensors. However, the ne...
Traffic congestion is a growing problem worldwide causing time/fuel waste, pollution, and even stress. Various approaches have been proposed to reduce traffic jams. Recently, researchers have started to employ connected vehicle (CV) technology. Most solutions, however, rely on a binary approach to determine a traffic jam, i.e., whether it exists or...
A traffic jam is one of the most significant social issues of our time.Wasted time and fuel due to traffic congestion causes economic losses not to mention driver’s stress. Various kinds of intelligent transportation systems (ITS) techniques have been developed to alleviate traffic jams. Recent research showed that vehicle-to-vehicle communication...
A traffic jam is one of the most significant social issues of our time.Wasted time and fuel due to traffic congestion causes economic losses not to mention driver’s stress. Various kinds of intelligent transportation systems (ITS) techniques have been developed to alleviate traffic jams. Recent research showed that vehicle-to-vehicle communication...
Traffic congestion is a growing problem worldwide causing time/fuel waste, pollution, and even stress. Various approaches have been proposed to reduce traffic jams. Recently, researchers have started to employ connected vehicle (CV) technology. Most solutions, however, rely on a binary approach to determine a traffic jam, i.e., whether it exists or...
Timely and efficient data dissemination is one of the fundamental requirements to enable innovative applications in vehicular cyber-physical systems (VCPS). In this work, we intensively analyze the characteristics of temporal data dissemination in VCPS. On this basis, we formulate the static and dynamic snapshot consistency requirements on serving...
In this work, we present ChildSafe, a classification system which exploits human skeletal features collected using a 3D depth camera to classify visual characteristics between children and adults. ChildSafe analyzes the histograms of training samples and implements a bin-boundary-based classifier. We train and evaluate ChildSafe using a large datas...
In this work, we address a fundamental problem of distinguishing the driver from passengers using a fusion of embedded sensors (accelerometers, gyroscopes, microphones, and magnetic sensors) in a smart phone. Compared with the state-of-the-art solutions, a key property of our solution is non-intrusiveness, i.e., enabling accurate driver phone detec...
Research on smart environments saturated with ubiquitous computing devices is rapidly advancing while raising serious privacy issues. According to recent studies, privacy concerns significantly hinder widespread adoption of smart home technologies. Previous work has shown that it is possible to infer the activities of daily living within environmen...
In a point-of-care (POC) setting, it is critically important to reliably count the number of specific cells in a blood sample. Software-based cell counting, which is far faster than manual counting, while much cheaper than hardware-based counting, has emerged as an attractive solution potentially applicable to mobile POC testing. However, the exist...
Recent advances in infrastructure-to-vehicle (I2V) and vehicle-to-vehicle (V2V) communications are envisioned to enable a variety of emerging applications in vehicular networks, where it is imperative to provide efficient data services via cooperative vehicular communications. In this work, we present the data dissemination system via cooperative I...
Duty-cycling is a primary technique significantly improving the energy efficiency of Wireless Sensor Networks (WSNs). Thus, a large number of MAC protocols have been developed for duty-cycled WSNs. Especially, recently proposed receiver-initiated MAC protocols are well suited for extremely low duty-cycled WSNs. However, as it is shown in this paper...
Falls are a significant problem for the elderly living independently in the home. Many falls occur due to household objects left in open spaces. We present KinSpace, a passive obstacle detection system for the home. KinSpace employs the use of a Kinect sensor to learn the open space of an environment through observation of resident walking patterns...
Falls are a significant problem for the elderly living independently in the home. Many falls occur due to household objects left in open spaces. We present KinSpace, a system that uses real-time depth data and human-in-the-loop feedback to adjust its understanding of the open space of an environment. We present results showing the effectiveness of...
Kintense is a robust, accurate, real-time, and evolving system for detecting aggressive actions such as hitting, kicking, pushing, and throwing from streaming 3D skeleton joint coordinates obtained from Kinect sensors. Kintense uses a combination of: (1) an array of supervised learners to recognize a predefined set of aggressive actions, (2) an uns...
An important function of many cyber-physical systems (CPS) is to provide a close monitoring of the operation environment to be able to adapt to changing situations effectively. One of the commonly applied techniques for that is to invoke time-constrained periodic application transactions to check the status of the operation environment. The status...
Recent advances in wireless communication technologies have spawned many new applications in vehicular networks. Data dissemination via roadside-to-vehicle communication is a vital approach to enabling most of these applications. In this work, we investigate in the scenario where data items are broadcasted from the road-side unit (RSU) in response...
To achieve the important aims of identifying and marking disease progression, cell counting is crucial for various biological and medical procedures, especially in a Point-Of-Care (POC) setting. In contrast to the conventional manual method of counting cells, a software-based approach provides improved reliability, faster speeds, and greater ease o...
Smart home environments require tight coupling between different types of sensors, actuators, and computer algorithms. To address the challenges in building a robust and effective smart home environment, it is essential to develop a systematic approach to handling a large number of components and their interactions. We describe a wholistic, multi-l...
Traffic congestion has become a major source of fuel waste, economic burden, environmental pollution, and commuter frustration. A lot of effort has been made to alleviate these problems, but traditional countermeasures, such as expanding transportation capacity, are no longer a sustainable solution to the rapidly growing levels of congestion. Both...
Query processing in mobile Wireless Sensor Networks (WSNs) is still a challenging problem because sensor mobility causes frequent changes of network topology. In this paper, we study the problem of processing Continuous Location Dependent Query (CLDQ) that retrieves the sampling data of the sensors within a specific area (i.e. query area) around a...
The goal of machine learning is to design and develop algorithms that allow systems to use empirical data, experience, and training to evolve and adapt to changes that occur in their environment. A major focus of machine learning research is to automatically induce models, such as rules and patterns, from the training data it analyzes. As shown in...
Inexpensive wireless sensing products are dramatically reducing the cost of in-home sensing. However, these sensors have been found to fail often and prohibitive maintenance costs may negate the cost benefits of inexpensive hardware and do-it-yourself installation. In this paper, we describe a new technique called SMART that uses application-level...
In this paper, we study the co-scheduling problem of periodic application transactions and update transactions in real-time database systems for surveillance of critical events. To perform the surveillance functions effectively, it is important to meet the deadlines of the application transactions and maintain the quality of the real-time data obje...
This paper presents PRIDE, a novel data abstraction layer for collaborative 2-tier sensor network applications. PRIDE, more specifically, targets distributed real-time applications, in which multiple collaborative mobile devices have to analyze a global situation by collecting and managing data streams from massive underlying sensors. PRIDE at thes...
Due to the explosive increases of data from both the cyber and physical worlds, the demand for database support in embedded systems is increasing. Databases for embedded systems, or embedded databases, are expected to provide timely in situ data services under various resource constraints, such as limited energy. However, traditional buffer cache m...
In a real-time database system for detection of critical events, meeting the deadlines of the application transactions and maintaining the quality of the real-time data objects are two critical issues in ensuring the effectiveness of performing the real-time monitoring tasks. Unfortunately, these two goals conflict with each other and are difficult...
One of the primary requirements in many cyber-physical systems (CPS) is that the sensor data derived from the physical world should be disseminated in a timely and reliable manner to all interested collaborative entities. However, providing reliable and timely data dissemination services is especially challenging for CPS since they often operate in...
Quality-aware realtime Embedded DataBase (QeDB) is a database for data-intensive real-time applications running on embedded devices. Currently, databases for embedded systems are best effort, providing no guarantees on their timeliness and data freshness. Existing real-time database (RTDB) technology cannot be applied to these embedded databases si...
The constantly increasing scale of sensor network deployments has brought up a number of resource utilization, communication, and computation issues. In this paper we present a model-driven tiered architecture that allows us to address some of those challenges. Preliminary results show that this architecture could save more than 90% of the original...
In many parts of the world, the ever-expanding traffic congestion problem has become a major source of wasted fuel, economic burden, and environmental pollution. Alleviating traffic congestion is not only a matter of expanding the transportation capacity, such as adding more lanes or building new roads, but also the problem of providing good traffi...
Component-based robot development has been a vibrant research topic in robotics due to its reusability and interoperability benefits. However, robot application developers using robot components must invest non-trivial amount of time and effort applying fault tolerance techniques into their robot applications. Despite the need for a common, framewo...
Achieving situation awareness is especially challenging for real-time data stream applications because they i) operate on continuous unbounded streams of data, and ii) have inherent realtime requirements. In this paper we showed how formal data stream modeling and analysis can be used to better understand stream behavior, evaluate query costs, and...
Achieving situation awareness is especially challenging for real-time data stream applications because they i) operate on continuous unbounded streams of data, and ii) have inherent real-time requirements. In this paper we show how formal data stream modeling and analysis can be used to better understand stream behavior, evaluate query costs, and i...
In many parts of the world, the ever-expanding traffic congestion problem has become a major source of wasted fuel, economic burden, and environmental pollution. Alleviating traffic congestion is not only a matter of expanding the transportation capacity, such as adding more lanes or building new roads, but also the problem of providing good traffi...
Event detection is a central component in numerous wireless sensor network (WSN) applications. In spite of this, the area of event description has not received enough attention. The majority of current event description approaches rely on using precise values to specify event thresholds. However, we believe that crisp values cannot adequately handl...
The majority of event detection in real-time embedded sensor network systems is based on data fusion that uses noisy sensor data collected from complicated real-world environments. Current research has produced several excellent low-level mechanisms to collect sensor data and perform aggregation. However, solutions that enable these systems to prov...
With the increased application of wireless sensor networks (WSNs) to military, commercial, and home environments, securing the data in the network has become a critical issue. Several security mechanisms, such as TinySec, have been introduced to address the need for security in WSNs. The cost of security, however, still mostly remains an unknown va...
With the increased application of wireless sensor networks (WSNs) in military, commercial, and home environments, securing the data in the network is a critical issue. Several security mechanisms, such as TinySec, have been introduced to address the need for security in WSNs. There are many applications, however, which require more than just protec...
Continuous and reliable operation of WSNs is notoriously difficult to guarantee due to hardware degradation and environmental changes. In this paper, we propose and demonstrate a methodology for run-time assurance (RTA), in which we validate at run time that a WSN will function correctly, despite any changes to the operating conditions since it was...
The demand for real-time data services is increasing in many large-scale distributed real-time applications incl uding advanced traffic control, global environment control, and t he nation-w