Hao-Hua Chu

Playful bottle: a mobile social persuasion system to motivate healthy water intake

This study of mobile persuasion system explores the use of a mobile phone, when attached to an everyday object used by an everyday behavior, becomes a tool to sense and influence that behavior. This mobile persuasion system, called Playful Bottle system, makes use of a mobile phone attached to an everyday drinking mug and motivates office workers to drink healthy quantities of water. A camera and accelerometer sensors in the phone are used to build a vision/motion-based water intake tracker to detect the amount and regularity of water consumed by the user. Additionally, the phone includes hydration games in which natural drinking actions are used as game input. Two hydration games are developed: a single-user TreeGame with automated computer reminders and a multi-user ForestGame with computer-mediated social reminders from members of the group playing the game. Results from 7-week user study with 16 test subjects suggest that both hydration games are effective for encouraging adequate and regular water intake by users. Additionally, results of this study suggest that adding social reminders to the hydration game is more effective than system reminders alone.

Sensor-assisted wi-fi indoor location system for adapting to environmental dynamics

Wi-Fi based indoor location systems have been shown to be both cost-effective and accurate, since they can attain meter-level positioning accuracy by using existing Wi-Fi infrastructure in the environment. However, two major technical challenges persist for current Wi-Fi based location systems, instability in positioning accuracy due to changing environmental dynamics, and the need for manual offline calibration during site survey. To address these two challenges, three environmental factors (people, doors, and humidity) that can interfere with radio signals and cause positioning inaccuracy are identified. Then, we have proposed a sensor-assisted adaptation method that employs RFID sensors and environment sensors to adapt the location systems automatically to the changing environmental dynamics. The proposed adaptation method performs online calibration to build multiple context-aware radio maps under various environmental conditions. Experiments were performed on the sensor-assisted adaptation method. The experimental results show that the proposed adaptive method can avoid adverse reduction in positioning accuracy under changing environmental dynamics.

CPU service classes for multimedia applications

We present the design, implementation, and experimental results of our soft real time (SRT) system for multimedia applications on top of a general purpose UNIX environment. The SRT system supports multiple CPU service classes for the real time processes based on their processor usage pattern including periodic constant processing time class (PCPT) and periodic variable processing time (PVPT) class. It also provides the following features: reservation and processing time guarantees for the service classes; overrun protection and scheduling algorithm; and system-initiated adaptation strategies. The other unique feature of the SRT system is its easy portability to any operating systems with real time extensions because it is implemented purely in the user space without any modifications to the kernel. We have implemented the SRT system on the Solaris 2.6 operating system with scheduling overhead under 400us and with good performance guarantees.

A secure multicast protocol with copyright protection

We present a simple, efficient, and secure multicast protocol with copyright protection in an open and insecure network environment. There is a wide variety of multimedia applications that can benefit from using our secure multicast protocol, e.g., the commercial pay-per-view video multicast, or highly secure military intelligence video conference. Our secure multicast protocol is designed to achieve the following goals. (1) It can run in any open network environment. It does not rely on any security mechanism on intermediate network switches or routers. (2) It can be built on top of any existing multicast architecture. (3) Our key distribution protocol is both secure and robust in the presence of long delay or membership message. (4) It can support dynamic group membership, e.g., JOIN/LEAVE/EXPEL operations, in a network bandwidth efficient manner. (5) It can provide copyright protection for the information provider. (6) It can help to identify insiders in the multicast session who are leaking information to the outside world. We have implemented a prototype system which validates our secure multicast protocol and evaluated it against various performance matrices. The experimental results are very encouraging, but also show where new engineering approaches need to be deployed to conform fully to the design goals.

A hybrid routing approach for opportunistic networks

With wireless networking technologies extending into the fabrics of our working and operating environments, proper handling of intermittent wireless connectivity and network disruptions is of significance. As the sheer number of potential opportunistic application continues to surge (i.e. wireless sensor networks, underwater sensor networks, pocket switched networks, transportation networks, and etc.), the design for an effective routing scheme that considers and accommodates the various intricate behaviors observed in an opportunistic network is of interest and remained desirable. While previous solutions use either replication or coding techniques to address the challenges in opportunistic networks, the tradeoff of these two techniques only make them ideal under certain network scenarios. In this paper, we propose a hybrid scheme, named H-EC, to deal with a wide variety of opportunistic network cases. H-EC is designed to fully combine the robustness of erasure coding based routing techniques, while preserving the performance advantages of replication techniques. We evaluate H-EC against other similar strategies in terms of delivery ratio and latency, and find that H-EC offers robustness in worst-case delay performance cases while achieving good performance in small delay performance cases. We also discuss the traffic overhead issues associated with H-EC as compared to other schemes, and present several strategies that can potentially alleviate the traffic overhead of H-EC schemes.

The diet-aware dining table: observing dietary behaviors over a tabletop surface

We are what we eat. Our everyday food choices affect our long-term and short-term health. In the traditional health care, professionals assess and weigh each individuals dietary intake using intensive labor at high cost. In this paper, we design and implement a diet-aware dining table that can track what and how much we eat. To enable automated food tracking, the dining table is augmented with two layers of weighing and RFID sensor surfaces. We devise a weight-RFID matching algorithm to detect and distinguish how people eat. To validate our diet-aware dining table, we have performed experiments, including live dining scenarios (afternoon tea and Chinese-style dinner), multiple dining participants, and concurrent activities chosen randomly. Our experimental results have shown encouraging recognition accuracy, around 80%. We believe monitoring the dietary behaviors of individuals potentially contribute to diet-aware healthcare.

Enabling Calorie-Aware Cooking in a Smart Kitchen

As a daily activity, home cooking is an act of care for family members. Most family cooks are willing to learn healthy cooking. However, learning healthy cooking knowledge and putting the learned knowledge into real cooking practice are often difficult, due to non-trivial nutritional calculation of multiple food ingredients in a cooked meal. This work presents a smart kitchen with UbiComp technology to improve home cooking by providing calorie awareness of food ingredients used in prepared meals during the cooking process. Our kitchen has sensors to track the number of calories in food ingredients, and then provides real-time feedback to users on these values through an awareness display. Our user study suggests that bringing calorie awareness can be an effective means in helping family cooks maintain the healthy level of calories in their prepared meals.

Collaborative localization: enhancing WiFi-based position estimation with neighborhood links in clusters

Location-aware services can benefit from accurate and reliable indoor location tracking. The widespread adoption of 802.11x wireless LAN as the network infrastructure creates the opportunity to deploy WiFi-based location services with few additional hardware costs. While recent research has demonstrated adequate performance, localization error increases significantly in crowded and dynamic situations due to electromagnetic interferences. This paper proposes collaborative localization as an approach to enhance position estimation by leveraging more accurate location information from nearby neighbors within the same cluster. The current implementation utilizes ZigBee radio as the neighbor-detection sensor. This paper introduces the basic model and algorithm for collaborative localization. We also report experiments to evaluate its performance under a variety of clustering scenarios. Our results have shown 28.2-56% accuracy improvement over the baseline system Ekahau, a commercial WiFi localization system.

Browser State Repository Service

We introduce browser state repository (BSR) service that allows a user to save and restore multiple independent snapshots of web sessions on a browser. At a later time, the user can retrieve any saved snapshot on a potentially different browser on a different device to continue any one of the chosen saved session in any order. The web session snapshot captures a complete browser running state, including the last page that appears on the browser, document object state, script state, values that a user enters in forms on the last page, browser history for back and forward pages, and cookies. BSR service consists of a browser plug-in that takes browser session snapshots, and a repository server that stores snapshots securely for each user. The main contribution of BSR service is that it decouples association between browser state and a device, in favor of association between browser state and its user.

Double-side multi-touch input for mobile devices

We present a new mobile interaction model, called double-side multi-touch, based on a mobile device that receives simultaneous multi-touch input from both the front and the back of the device. This new double-sided multi-touch mobile interaction model enables intuitive finger gestures for manipulating 3D objects and user interfaces on a 2D screen.