2076832
Iterative adaptation for mobile clients using existing APIs
Iterative adaptation is a novel approach to adaptation for resource-limited mobile and wireless environments that supports powerful application-specific adaptations without requiring modifications to the application's source code. Common productivity applications, such as browsers, word processors, and presentation tools, export APIs that allow external applications to control their operation. The novel premise in iterative adaptation is that these APIs are sufficient to support a wide range of adaptation policies for applications running on resource-limited devices. In addition to allowing adaptation without having to change the application's source code, this approach has a unique combination of advantages. First, it supports centralized management of resources across multiple applications. Second, it makes it possible to modify application behavior after the application has been deployed. This paper evaluates the extent to which existing APIs can be used for the purposes of adapting document-based applications to run on bandwidth-limited devices. In particular, we implement a large number of bandwidth adaptations for applications from the Microsoft Office and the OpenOffice productivity suites and for Internet Explorer. Although we find limitations in their APIs, we are able to implement many adaptation policies without much complexity and with good performance. Moreover, iterative adaptation achieves performance similar to an approach that implements adaptation by modifying the application, while requiring only a fraction of the coding effort.
960483
Selecting devices for aggregation
As intelligent devices become affordable and wireless infrastructure becomes pervasive, the potential to combine, or aggregate, device functionality to provide a user with a better experience grows. Often, there will be multiple devices providing similar functionality that the user will have to choose from for the aggregation. We present the design and prototype implementation of a system for automatic selection of devices for aggregation in a dynamic environment. It allows a user to express trade-offs between the quality of device attributes, user distraction, and aggregation stability. This approach enables a user to have a richer experience without having to constantly worry about the device and the environment details.
15398191
Precise static type analysis for object oriented programs
A precise static type analysis is important to make available dynamic aspects of object-oriented programs (OOPs) approximately known at compile-time. Many techniques have been proposed for static type analysis depending upon the tradeoff of cost and precision; the techniques may generate spurious possible types for a particular dynamic dispatch which makes the static type analysis imprecise. In this paper, we propose a symbolic execution based type analysis technique that analyzes the dynamic type inter-procedurally by keeping the flow of the program in consideration. We analyze test cases with different class hierarchies. The proposed technique was capable to resolve the target method for most of the dynamic dispatches at reduced computational cost.
1384171
Efficient Hybrid Security Mechanisms for Heterogeneous Sensor Networks
Many applications that make use of sensor networks require secure communication. Because asymmetric-key solutions are difficult to implement in such a resource-constrained environment, symmetric-key methods coupled with a priori key distribution schemes have been proposed to achieve the goals of data secrecy and integrity. These approaches typically assume that all nodes are similar in terms of capabilities and, hence, deploy the same number of keys in all sensors in a network to provide the aforementioned protections. In this paper, we demonstrate that a probabilistic unbalanced distribution of keys throughout the network that leverages the existence of a small percentage of more capable sensor nodes can not only provide an equal level of security, but also reduce the consequences of node compromise. To fully characterize the effects of the unbalanced key management system, we design, implement, and measure the performance of a complementary suite of key establishment protocols known as LIGER. Using their predeployed keys, nodes operating in isolation from external networks can securely and efficiently establish keys with each other. Should resources such as a backhaul link to a key distribution center (KDC) become available, networks implementing LIGER automatically incorporate and benefit from such facilities. Detailed experiments demonstrate that the unbalanced distribution in combination with the multimodal LIGER suite offers a robust and practical solution to the security needs in sensor networks
3134095
Supervisory Control of Real-Time Systems Using Prioritized Synchronization
The theory of supervisory control of discrete event systems is extended to the real-time setting. The real-time behavior of a system is represented by the set of all possible timed traces of the system. This is alternatively specified using timed automata where each transition is associated with an event occurrence time set during which time the transition can occur. Our model for time is more general in that the time advances continuously as compared to a model where time advances discretely. We extend the notion of prioritized synchronous composition to the real-time setting to use it as the control mechanism. It is shown that a suitable extension of the controllability condition to the real-time setting yields a condition for the existence of a supervisor achieving a desired timed behavior. Although the real-time controllability is similar in form to its untimed counterpart, they are different in the sense that one does not imply the other and vice-versa.
537233
Evolutionary Multimodal Optimization Revisited
We revisit a class of multimodal function optimizations using evolutionary algorithms reformulated into a multiobjective framework where previous implementations have needed niching/sharing to ensure diversity. In this paper, we use a steady-state multiobjective algorithm which preserves diversity without niching to produce diverse sampling of the Pareto-front with significantly lower computational effort.
6817196
Design of Adaptive Overlays for Multi-scale Communication in Sensor Networks
In wireless sensor networks, energy and communication bandwidth are precious resources. Traditionally, layering has been used as a design principle for network stacks; hence routing protocols assume no knowledge of the application behavior in the sensor node. In resource-constrained sensor-nodes, there is simultaneously a need and an opportunity to optimize the protocol to match the application. In this paper, we design a network architecture that efficiently supports multi-scale communication and collaboration among sensors. The architecture complements the previously proposed Abstract Regions architecture for local communication and collaboration. We design a self-organizing hierarchical overlay that scales to a large number of sensors and enables multi-resolution collaboration. We design effective Network Programming Interfaces to simplify the development of applications on top of the architecture; these interfaces are efficiently implemented in the network layer. The overlay hierarchy can adapt to match the collaboration requirements of the application and data both temporally and spatially. We present an initial evaluation of our design under simulation to show that it leads to reduced communication overhead, thereby saving energy. We are currently building our architecture in the TinyOS environment to demonstrate its effectiveness.