1097041
Acoustic Target Tracking Using Tiny Wireless Sensor Devices
With the advancement of MEMS technologies, wireless networks consist of tiny sensor devices hold the promise of revolutionizing sensing in a wide range of application domains because of their flexibility, low cost and ease of deployment. However, the constrained computation power, battery power, storage capacity and communication bandwidth of the tiny devices pose challenging problems in the design and deployment of such systems. Target localization using acoustic signal with tiny wireless devices is a particularly difficult task due to the amount of signal processing and computation involved. In this paper, we provide an in-depth study of designing such wireless sensor networks for real-world acoustic tracking applications. We layout a cluster-based architecture to address the limitations of the tiny sensing devices. To achieve effective utilization of the scarce wireless bandwidth, a quality-driven paradigm to suppress redundant information and resolve contention is proposed. One instance of the quality-driven approach is implemented in the acoustic tracking system, where the quality of the tracking reports can be quantified numerically. We demonstrate the effectiveness of our proposed architecture and protocols using a sensor network testbed based on UCBerkeley mica motes. Considering the performance limitations of tiny sensor devices, the achieved acoustic target tracking accuracy is extraordinarily good. Our experimental study also shows that the acoustic target tracking quality can be indeed measured and used to assist resource allocation decisions. This application-driven design and implementation exercises also serve to identify important areas of further work in in-network processing and communications.
17067182
A dependable online testing and upgrade architecture for real-time embedded systems
When real-time embedded system software needs to be upgraded, it will be more dependable if the new software is sufficiently tested on the actual deployment platform. The challenge is to provide a safeguard for protecting the normal operations from faulty upgrades. However, the safeguard must be not only efficient but also able to be added and taken away as needed without shutting down the normal operations. We have developed an architecture based on simplex architecture and process resurrection and have applied it to the inverted pendulum control system. The measurements show that the overhead is small and justifiable.
15404238
Process resurrection: a fast recovery mechanism for real-time embedded systems
This paper describes a fast recovery mechanism that meets the requirements of embedded real-time systems. In general purpose computing, restart is an established technology for achieving high availability. Restart has also been used in soft real-time systems where the temporary interruption of service is undesirable but acceptable. However, it has not been widely used in small embedded real-time systems with hard deadlines, mainly because the traditional approaches do not meet their requirements of low memory and processor overhead, and fast response times with little variations. We have developed process resurrection, a novel restart mechanism for recovering from crash failures to meet these requirements. The experiments on an inverted pendulum control system shows that it can recover the control process in time after a crash (eg. segmentation fault). Another experiment conducted on an MP3 audio player shows that this technique is also applicable to some multimedia applications.
42709388
Precomputing avatar behavior from human motion data
206754652
On the reconfigurability of single-hub WDM ring networks
We study the benefit of reconfigurability for wavelength division multiplexed (WDM) ring networks with dynamic single-hubbed traffic. We showthat the ability to reconfigure wavelength add-drop multiplexers helps to reduce the number of expensive line terminating equipment (LTEs) by a factor of W, where W is the number of wavelengths in the network. In addition, we show that for a general class of traffic, optical networks using reconfigurable wavelength add-drop multiplexers guarantee to be almost as bandwidth efficient as full wavelength add-drop networks, that is, opaque networks. For such traffic, we introduce several fast algorithms that achieve or approximate the optimal performance guarantees. The comparison between reconfigurable networks and opaque networks is quantified using a performance metric called capacity ratio, which captures the relative throughput performance of a reconfigurable network compared to the opaque network.
11059176
Policy-based validation of SAN configuration
Historically, storage has been directly connected to servers for fast local access and easy configuration. In recent years, storage area networks (SANs) have defined an alternative storage paradigm that allows storage to be shared among servers using fast interconnects. One of the key challenges of SAN management is the large number of configuration problems that are encountered in a typical SAN deployment. These configuration problems can be addressed by SAN management software. However, hard-coding the SAN configuration rules into the management software is not a viable option since it is not possible to easily modify or replace old configuration rules and specify new policies and guidelines. In this paper, we propose a novel policy-based SAN configuration validation system that can be used to specify, store, and evaluate configuration policies for SANs. We also introduce five new operators for collection policies that are useful for evaluating a wide variety of practical SAN configuration policies found in practice. The policy-based SAN configuration checking approach proposed in this paper is discussed within the context of device interoperability constraints. However, this approach is extensible as it can also be used to enforce performance, reliability, and security-related configuration constraints.
30255791
Adaptive Model-Based Multi-person Tracking
This paper proposes a method for tracking and identifying persons from video image frames taken by a fixed camera. The majority of conventional video tracking surveillance systems assumes a likeness to a person's appearance for some time, and existing human tracking systems usually consider short-term situations. To address this situation, we use an adaptive background and human body model updated statistically frame-by-frame to correctly construct a person with body parts. The formed person is labeled and recorded in a person's list, which stores the individual's human body model details. Such recorded information can be used to identify tracked persons. The results of this experiment are demonstrated in several indoor situations.
6972987
Scalable service differentiation in a shared storage cache
Motivated by the need to enable easier data sharing and curb rising storage management costs, storage systems are becoming increasingly consolidated and thereby shared by a large number of users and applications. In such environments, service differentiation becomes increasingly important. Since caching is a fundamental and pervasive technique employed to improve the performance of storage systems, providing differentiated services from a storage cache is a crucial component of the entire end-to-end QoS solution. In this paper we discuss a QoS architecture for a shared storage proxy cache which can provide long-term hit rate assurances to competing classes. The proposed architecture consists of three components: (a) per-class feedback controllers that track the performance of each class, (b) a fairness controller that allocates excess resources fairly in the case when all goals are met, and (c) a contention resolver that decides cache allocation in the case when at least one class does not meet its target hit rate. We compare the performance of various feedback per-class controllers, and provide guidelines for designing QoS mechanisms for such a dynamic environment.