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A unique crossed electrode array is described for real-time volume ultrasound imaging. The studies have shown that by using a 288-element crossed electrode pattern, a large field of view volume images at real-time frame rates is obtained, with image contrast and resolution comparable to the results obtained by using a conventional 128-element linear phased array.

The increased computational demands of a frequency-diverse ultrasonic target detection system are addressed by developing a zero-phase ZP (ZP-IIR) filter. A small number of coefficients inherent to IIR filters and their multiplierless implementation have provided a good architecture suitable for compact, real-time ultrasonic imaging devices.

This paper presents a novel, real-time digital image stabilization (DIS) system using a modified proportional integrated (MPI) controller to remove stably unwanted shaking from an image sequence that is captured by a hand-held video camera without affecting the deliberate panning motion of the camera. Researchers have addressed the trade-off problem between the removal of shaking and the preservation of global camera movement. This paper analyzes motion compensation, which is formulated as a control problem. A compensating motion vector (CMV) estimation method with a modified PI control system is proposed both to remove the unwanted jitter and to preserve the deliberate, panning motion of the camera. Experimental results demonstrate that the proposed system provides robust motion compensation of image sequences in various conditions. Index Terms--Digital image stabilizer, DIS, proportional integrated controller, PI controller, smooth index.

Fieldbus systems are well known in the industrial automation world. Due to the increasing demand for scalability and capability of working in harsh environment, the use of wireless communication is gaining in importance. In the past, some efforts were pursued to encapsulate wired standards over wireless link, but their diffusion is limited by reliability and predictability requirements. In addition, event-driven protocols borrowed from the consumer world (as IEEE802.11 or IEEE802.15.4) are not well suited for some industrial applications. In this paper, authors present the design and the experimental evaluation of a wireless real-time communication protocol that tries to overcome these limits. It exploits standard hardware to lower cost and implements a hybrid medium access strategy. Time Division Multiple Access scheduling is used to ensure time deadlines respect, while Carrier Sense Multiple Access with Collision Avoidance is used for acyclic communications, as those involved in network management. It has been successfully adopted for temperature monitoring in plastic machineries. The prototype network adopts star topology and can manage up to 16 nodes with a refresh time of 128 ms. Index Terms--Low-power system, real-time systems, synchronization, wireless sensor network (WSN).

The prospects for the real-time amplitude estimation of selected harmonic components of quasi-periodic signals from a motional Stark effect (MSE) tokamak plasma diagnostic is addressed using Kalman filtering techniques. The proposed method is shown to be more competitive than a standard low-pass filter lock-in amplifier scheme. In particular, when block data processing is limited to a small number of samples signal harmonics are narrowly separated in frequency or in the presence of frequency jitter, the superior competencies of the Kalman filtering method are evidenced. Index Terms--Diagnostics, estimation, plasma measurements, real-time systems, signal processing.

We propose a novel approach based on predictive quantization (PQ) for online summarization of multiple time-varying data streams. A synopsis over a sliding window of most recent entries is computed in one pass and dynamically updated in constant time. The correlation between consecutive data elements is effectively taken into account without the need for preprocessing. We extend PQ to multiple streams and propose structures for real-time summarization and querying of a massive number of streams. Queries on any subsequence of a sliding window over multiple streams are processed in real time. We examine each component of the proposed approach, prediction, and quantization separately and investigate the space-accuracy trade-off for synopsis generation. Complementing the theoretical optimality of PQ-based approaches, we show that the proposed technique, even for very short prediction windows, significantly outperforms the current techniques for a wide variety of query types on both synthetic and real data sets. Index Terms--Multiple streams, predictive quantization, data summarization, synopsis, online update, time-varying data.

Two procedures for validating track estimate obtained using the maximum-likehood probabilistic data association (ML-PDA) algorithm is presented.

Implementation of real-time neural network inversion on the SRC-6e, a computer that uses multiple field-programmable gate arrays (FPGAs) as reconfigurable computing elements, is examined using a sonar application as a specific case study. A feedforward multilayer perceptron neural network is used to estimate the performance of the sonar system (Jung et al., 2001). A particle swarm algorithm uses the trained network to perform a search for the control parameters required to optimize the output performance of the sonar system in the presence of imposed environmental constraints (Fox et al., 2002). The particle swarm optimization (PSO) requires repetitive queries of the neural network. Alternatives for implementing neural networks and particle swarm algorithms in reconfigurable hardware are contrasted. The final implementation provides nearly two orders of magnitude of speed increase over a state-of-the-art personal computer (PC), providing a real-time solution. Index Terms--Field-programmable gate arrays (FPGAs), inverse problems, neural network hardware, particle swarm theory, real-time systems, reconfigurable architectures, sonar.

The development of efficient ultrawideband (UWB) systems for high-rate wireless links requires an accurate knowledge of the radio propagation mechanisms. Anticipated usage scenarios in office or residential environments predict a significant impact of mobile persons on the UWB radio link. However, the issue of temporal variations in the UWB propagation channel has been scarcely investigated so far. This paper presents a study of the time variance of a UWB channel induced by the motion of people, with a specific focus on the main path of a line-of-sight radio link. A real-time measurement campaign involving moving scatterers was performed in the 4-5 GHz band, in a hallway of a typical office building. The analysis of measured data, regarding the shadowing effect and fast signal fluctuations, provides a detailed description of the phenomena involved in a time varying UWB channel. As a result, a model is described for the temporal variations observed on the main propagation path in a fixed UWB link, accounting for both the nonstationary attenuation due to obstructing people and the small-scale signal variations due to scattered propagation paths. Index Terms--Modeling, radio propagation, time-varying channels, ultrawideband (UWB).

A method for topology error identification based on collinearity tests involving Lagrange multipliers and the columns of the corresponding covariance matrix is presented. It relies on a geometric interpretation of the multipliers associated with the equality constraints that model circuit breaker status in generalized state estimation. The method is conceptually simple, and its implementation requires little computational effort, therefore being suitable for real-time applications. Results of several simulated cases conducted at the substation level on a real-life test system based on a subnetwork of the Brazilian Northern power system are used to illustrate the performance of the proposed technique. Index Terms--Bad data analysis, power system real-time operation, power system state estimation.

With the increasing use of real-time synchronized phasor measurement units, it is necessary to consider applications of these measurements in greater detail. One of the most natural applications of these measurements is in the area of state estimation. A straightforward application of state estimation theory treats phasor measurements of currents and voltages as additional measurements to be appended to traditional measurements now being used in most energy management system (EMS) state estimators. The resulting state estimator is once again nonlinear and requires significant modifications to existing EMS software. This paper proposes an alternative approach, which leaves the traditional state estimation software in place, and discusses a novel method of incorporating the phasor measurements and the results of the traditional state estimator in a postprocessing linear estimator. This paper presents the underlying theory and provides verification through simulations of the two alternative strategies. It is shown that the new technique provides the same results as the nonlinear state estimator and does not require modification of the existing EMS software. Index Terms--Phasor measurements, phasor measurement units (PMUs), power systems, real-time measurements, state estimation, synchronized measurements.

This paper describes verification of five conjectures related to power system controlled separation. It attempts to verify that the location of uncontrolled separation (loss of synchronism or out-of-step operation) is independent of the location and severity (short-circuit duty or duration) of the initial faults, that the location depends on the prevailing network configuration and load level, and that it takes place one operation at a time (cascades). Verification of these conjectures would allow controlled separation during a disturbance in real-time, using the present communication and protection systems, and results in a minimal load and generation imbalance. Two actual power systems were used, a 50-bus system to establish the procedure for controlled separation and a 640-bus interconnection to apply the procedure. Data representing static and dynamic behavior of the two power systems were obtained from the operating utilities, and the many required simulations were conducted using EPRI Power System Analysis Package (including IPFLOW and ETMSP programs). Index Terms--Controlled separation, graceful degradation, out-of-step blocking, system separation, transfer tripping.

Characterization of the dynamic phenomena that arise when the system is subjected to a perturbation is important in real-time power system monitoring and analysis. This paper discusses the use of Hilbert spectral analysis to visualize and characterize nonlinear oscillations from synchronized wide-area measurements. The method has the potential to be applied for real-time, wide-area monitoring and analysis. As an illustrative example, synchronized phasor measurements of a real event in northern Mexico are used to examine the potential usefulness of nonlinear time series analysis techniques to characterize the time evolution of nonlinear, nonstationary oscillations and to determine the nature and propagation of the system disturbance. The proposed approach is also compared with Prony analysis. Index Terms--Interarea oscillations, spectral analysis, wide-area measurements.

The static staging heuristics for staging data items related with real-time distributed applications stick to a method by which only one data item is transferred in a communication step to optimize a particular cost function and Extended Partial Path (EPP) algorithm is presented. The analytical results confirm that EPP performs equally or better than Partial Path Heuristic (PPH) and concurrent scheduling (CS) heuristic based on EPP is described which enables transfer of more than one data item in a organized manner simultaneously and results confirm the supremacy of CS over PPH.

The industrial network, often referred to as fieldbus, becomes an indispensable component for intelligent manufacturing systems. Thus, in order to satisfy the real-time requirements of field devices such as sensros, actuators, and controllers, numerous fieldbus protocols have been developed. But, the application of fieldbus has been limited due to the high cost of hardware and the difficulty in interfacing with multivendor products. As an alternative to fieldbus, the Ethernet (IEEE 802.3) technology is being adapted to the industrial environment. However, the crucial technical obstacle of Ethernet is its nondeterministic behavior that cannot satisfy the real-time requirements. Recently, the switched Ethernet becomes a very promising alternative for real-time industrial application due to the elimination of uncertainties in Ethernet. This paper focuses on the application of the switched Ethernet with multiple levels (that is, cascade structure with multiple switching hubs) for real-time industrial networking. More specifically, this paper presents an analytical performance evaluation of the switched Ethernet with multiple levels from timing diagram analysis, and experimental evaluation from an experimental testbed of networked control system. Index Terms--Fieldbus, industrial network, network delay, networked control system (NCS), real-time requirements, switched Ethernet.

We show how commodity CPU, networking and memory components greatly simplify a sophisticated trigger system designed for the demanding environment of a high data rate hadron collider experiment operating at 2 x [10.sup.32] [cm.sup.-2][s.sup.-1]. The trigger system is based on an 8-fold way, 3-level architecture capable of processing over 22 million data channels at a crossing rate of 2.5 MHz with a mean value of 6 interactions per crossing. Although originally designed for a B-physics experiment at the Tevatron, the flexible and highly scalable nature of the design should also be relevant to other next generation hadron collider experiments such as those at the LHC. Index Terms--Data acquisition, elementary particles, real time systems.

The fusion experiment Wendelstein 7-X demands synchronizing processes in many distributed technical components with an accuracy from milliseconds to nanoseconds. For this purpose a Trigger-Time-Event system (TTE system) was developed. Its main task is the synchronization of all control components and data acquisition systems. It allows time stamping, processing of trigger signals and event messages. The TTE system offers the possibility to program timing sequences and delays, logic combinations or conditions. After a description of the TTE system the task synchronization in the control system of WENDELSTEIN 7-X is discussed. A special software library (TimeLib) allows dealing with time related variables in a simple and comfortable manner. The efficiency of the synchronization system is exemplified. Index Terms--Control system, distributed real time system, fusion experiment, synchronization, timing system.

The More-Less (ML) scheme has been shown to be an efficient approach for maintaining temporal consistency of real-time data objects. Although ML provides a deterministic guarantee in temporal consistency, the number of update transactions that can be supported in a system is limited. This is due to its use of the worst-case computation time in deriving deadlines and periods of update transactions. This paper studies the problem of temporal consistency maintenance where a certain degree of temporal inconsistency is tolerable. A suite of Statistical More-Less (SML) approaches are proposed to explore the trade-off between quality of service (QoS) of temporal consistency and the number of supported transactions. It begins with a base-line algorithm, SML-BA, which provides the requested QoS of temporal consistency. Then, SML with Optimization (SML-OPT) is proposed to further improve the QoS by better utilizing the excess processor capacity. Finally, SML-OPT is enhanced with a Slack Reclaiming scheme (SML-SR). The reclaimed slacks are used to process jobs whose required computation time is larger than the guaranteed computation time. Simulation experiments are conducted to compare the performance of these schemes (SML-BA, SML-OPT, and SML-SR) together with the deterministic More-Less and Half-Half schemes. The results show that the SML schemes are effective in trading the schedulability of transactions for the QoS guaranteed. Moreover, SML-SR performs best and offers a significant QoS improvement over SML-BA and SML-OPT. Index Terms--Real-time database, probabilistic temporal consistency, transactions scheduling, quality of service.