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.
5790802
Object-oriented symbol management in syntax-directed compiler systems
Each symbol in a source program has a series of attributes that govern the operations performed on it. In this paper, we explore object-oriented techniques for representing the attributes of symbols and translating the operations performed on them. This approach is shown superior in memory and run-time speed to the procedural style traditionally used for writing compilers. We demonstrate object-oriented symbol management in a compiler for an arithmetic subset of C. We have used C++ --- a single-dispatching language --- to implement the same, but we emphasize the need for multiple dispatching to develop programs in a heavily-object-oriented style.
39625638
Distributed dynamic slicing of Java programs
We propose a novel dynamic slicing technique for distributed Java programs. We first construct the intermediate representation of a distributed Java program in the form of a set of Distributed Program Dependence Graphs (DPDG). We mark and unmark the edges of the DPDG appropriately as and when dependencies arise and cease during run-time. Our algorithm can run parallely on a network of computers, with each node in the network contributing to the dynamic slice in a fully distributed fashion. Our approach does not require any trace files to be maintained. Another advantage of our approach is that a slice is available even before a request for a slice is made. This appreciably reduces the response time of slicing commands. We have implemented the algorithm in a distributed environment. The results obtained from our experiments show promise.
11255660
A flexible contention resolution scheme for QoS provisioning in optical burst switching networks
Contention resolution is a major issue in bufferless optical burst switching (OBS) networks. The existing contention resolution schemes consider priority and arrival time to resolve contention. For most multimedia applications priority and delay are key parameters for QoS provisioning. In this paper, we propose a new signaling protocol for reducing contention in OBS networks and consider three parameters, namely, priority of the burst, number of hops traversed, and burst size into account to resolve contention. The source node in the proposed protocol can be informed of the contention up to halfway along the path of the burst, and thus, can reschedule the burst accordingly. The scheme is adaptable to both prioritized and delay constrained traffic. We call the scheme OBS-Flex. For selecting a data channel, we propose three channel selection algorithms, namely, Least Recently Used (LRU), First Fit (FF), and Priority Set (PS). We simulate OBS-Flex and compare with preemptive priority just-enough-time (PPJET) contention resolution scheme. We show that OBS-Flex outperforms PPJET in terms of burst loss rates. For simulation, we have considered Poisson and bursty traffic models.
24684227
Adaptive Control of Anytime Algorithm Parameters
6342150
Frame based fair multiprocessor scheduler: a fast fair algorithm for real-time embedded systems
This paper presents frame based fair multiprocessor scheduler (FBFMS) which provides accurate real-time proportional fair scheduling for a set of dynamic tasks on a symmetric multiprocessor environment with O(1) scheduling overhead. FBFMS meets these seemingly contradictory goals by applying the benefits of virtual time round-robin scheduling mechanism along with a frame based scheduling approach. Simulation results show that the algorithm provides 2.5 to 26 times speedup (over O(lg n) complexity schedulers) with distortion in fairness less than 1% in most cases, and less than 15% in the worst case.
9633354
Real-time personalized sports video filtering and summarization
We demonstrate a real-time fully automated software system for filtering important events in sports video. Events represent occurrences of actions or state changes in video content. In the current prototype, we demonstrate detection of pitching in baseball and serving in tennis. For wireless video applications, we propose and apply a unique notion of content-based adaptive streaming,in which video encoding rate and media modality is dynamically varied according to the event filtering results. Our system includes an event detection module, an adaptive encoding module, and a buffer management module for adaptive streaming. We achieve the real-time performance by exploring compressed-domain techniques and multi-stage multi-resolution content-analysis processes.
22550674
Timing-sync protocol for sensor networks
Wireless ad-hoc sensor networks have emerged as an interesting and important research area in the last few years. The applications envisioned for such networks require collaborative execution of a distributed task amongst a large set of sensor nodes. This is realized by exchanging messages that are time-stamped using the local clocks on the nodes. Therefore, time synchronization becomes an indispensable piece of infrastructure in such systems. For years, protocols such as NTP have kept the clocks of networked systems in perfect synchrony. However, this new class of networks has a large density of nodes and very limited energy resource at every node; this leads to scalability requirements while limiting the resources that can be used to achieve them. A new approach to time synchronization is needed for sensor networks.In this paper, we present Timing-sync Protocol for Sensor Networks (TPSN) that aims at providing network-wide time synchronization in a sensor network. The algorithm works in two steps. In the first step, a hierarchical structure is established in the network and then a pair wise synchronization is performed along the edges of this structure to establish a global timescale throughout the network. Eventually all nodes in the network synchronize their clocks to a reference node. We implement our algorithm on Berkeley motes and show that it can synchronize a pair of neighboring motes to an average accuracy of less than 20ms. We argue that TPSN roughly gives a 2x better performance as compared to Reference Broadcast Synchronization (RBS) and verify this by implementing RBS on motes. We also show the performance of TPSN over small multihop networks of motes and use simulations to verify its accuracy over large-scale networks. We show that the synchronization accuracy does not degrade significantly with the increase in number of nodes being deployed, making TPSN completely scalable.
62235343
A simulation-based study of wireless sensor network middleware
Future wireless sensor networks (WSNs) will transport high-bandwidth, low-latency streaming data, and will host sophisticated processing, such as image fusion and object tracking, in-network on sensor network nodes. Recent middleware proposals provide capabilities for in-network processing, reducing energy drain based on communication costs alone. However, hosting complex processing on WSN nodes incurs additional processing energy and latency costs that impact network lifetime and application performance. There is a need for a WSN planning framework to explore energy saving and application performance trade-offs for models of future sensor networks that account for processing costs in addition to communication costs. In this work, we present a simulation framework to analyze the interplay between resource requirements for compute-and communication-intensive in-network processing for streaming applications. We simulate a surveillance application workload with middleware capabilities for data fusion, adaptive policy-driven migration of data fusion computation across network nodes, and prefetching of streaming data inputs for fusion processing. Our study sheds light on application figures of merit such as latency, throughput, and lifetime with respect to migration policy and node CPU and radio characteristics.
262403
Collaboration and multimedia authoring on mobile devices
This paper introduces adaptation-aware editing and progressive update propagation, two novel mechanisms that enable authoring multimedia content and collaborative work on mobile devices. Adaptation-aware editing enables editing content that was adapted to reduce download time to the mobile device. Progressive update propagation reduces the time for propagating content generated at the mobile device by transmitting either a fraction of the modifications or transcoded versions thereof.With application-aware editing and progressive update propagation, an object present at a mobile device is characterized not only by a particular version, as in conventional replication, but also by a particular fidelity. We demonstrate that replication models can be extended to account for fidelity independently of the mechanisms used for concurrency control and consistency maintenance. As a result, the two techniques described in this paper can easily be added to any replication protocol, whether optimistic or pessimistic.We report on our experience implementing adaptation-aware editing and progressive update propagation. Experiments with two multimedia applications, an email reader and a presentation software package, show that both mechanisms can be added with modest programming effort and achieve substantial reductions in upload and download latencies.
7339641
Efficient beacon placement for network tomography
Recent interest in using tomography for network monitoring has raised the fundamental issue of whether it is possible to use only a small number of probing nodes (beacons) for monitoring all edges of a network in the presence of dynamic routing. Past work has shown that minimizing the number of beacons is NP-hard, and has provided approximate solutions that may be fairly suboptimal. In this paper, we use a two-pronged approach to compute an efficient beacon set: (i) we formulate the need for, and design algorithms for, computing the set of edges that can be monitored by a beacon under all possible routing states; and (ii) we minimize the number of beacons used to monitor all network edges. We show that the latter problem is NP-complete and use an approximate placement algorithm that yields beacon sets of sizes within 1+<i>ln</i>(|<i>E</i>|) of the optimal solution, where E is the set of edges to be monitored. Beacon set computations for several Rocketfuel ISP topologies indicate that our algorithm may reduce the number of beacons yielded by past solutions by more than 50%.