6735701
Dependency algebra: a theoretical framework for dependency management in real-time control systems
The large and complex dependency relationship between software components is at the root of system instability. A seemingly minor fault can propagate along dependency chains and bring down the system. Therefore, the first step in the development of a robust system is the management and control of dependency relations between software components. The two contributions of this paper are: 1) a refinement of the commonly used failure semantics in the context of a real time control system; 2) the development of a dependency algebra. Component dependency relationships can be described in terms of a set of refined failure semantics mappings, enabling differentiation and comparison of different relationships and designs. The system-wide evaluation and tracking of these dependency relationships are performed using dependency algebra.
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.
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.
14233498
Efficient mobility management for multimedia service in wireless IP networks
Multimedia service in wireless IP networks, most delays and disruptions happening on the handoff of nodes are related to AAA. There were many studies on attempting to reduce the delay happening on the handoffs, and among them, there is the shadow registration as a suitable method for seamless mobility. Shadow registration is a method preparing against the following handoff by registering to all neighboring cells in prior, and is efficient in reducing the handoff delay. However, this method causes heavy traffic as well as the waste of resources. In order to prohibit the increase of traffic among the nodes while having the reducing effect on delay time, we proposes a technique and algorithm for composing region-based shadow registration (RSR) that provides seamless mobility, which does not cause traffic and the waste of resources. We have introduced a cell division scheme for minimal shadow registration and its algorithm. The results of the experiments performed by simulations displayed the identical effect of reducing the delay as shadow registration while significantly reducing the traffic among the nodes.
2700489
An efficient algorithm for predictive continuous nearest neighbor query processing and result maintenance
Predictive continuous nearest neighbor queries are concerned with finding the nearest neighbor objects for some future time period according to the current object and query locations and their motion information. Existing continuous query processing algorithms are not efficient enough, requiring multiple dataset lookups to evaluate the query results throughout the duration of a continuous query. More importantly, the complete result for the whole query time interval is only available at the moment when all object motion updates have been examined, based on which adjustment of the query result is made. In this paper, we propose an algorithm which requires only one dataset lookup to deliver a complete predictive result. We then apply a differential update technique to maintain the query results incrementally in the presence of object location and motion updates.
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.
321298
NETKIT: a software component-based approach to programmable networking
While there has already been significant research in support of openness and programmability in networks, this paper argues that there remains a need for generic support for the integrated development, deployment and management of programmable networking software. We further argue that this support should explicitly address the management of run-time reconfiguration of systems, and should be independent of any particular programming paradigm (e.g. active networking or open signaling), programming language, or hardware/ operating system platform. In line with these aims, we outline an approach to the structuring of programmable networking software in terms of a ubiquitously applied software component model that can accommodate all levels of a programmable networking system from low-level system support, to in-band packet handling, to active networking execution environments to signaling and coordination.
10984576
Are physically embodied social agents better than disembodied social agents?: The effects of physical embodiment, tactile interaction, and people's loneliness in human-robot interaction
Two experiments were conducted to investigate the effects of physical embodiment in human-agent interaction. Experiment 1 (N=32) shows positive effects of physical embodiment on the feeling of an agent's social presence, the evaluation of the agent, the assessment of public evaluation of the agent, and the evaluation of the interaction with the agent. A path analysis reveals that the feeling of the agent's social presence mediates the participants' evaluation of the social agent. Experiment 2 (N=32) shows that physical embodiment with restricted tactile interaction causes null or even negative effects in human-agent interaction. In addition, Experiment 2 indicates that lonely people feel higher social presence of social agents, and provide more positive social responses to social agents than non-lonely people. The importance of physical embodiment and tactile communication in human-agent interaction and the diverse role of social robots, especially for the lonely population, are discussed.