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Hermite polynomial chaos is used to create models of electric circuit branches for the study of random changes of parameters. The proposed method allows for seamless integration with nodal analysis. An analogy of Fourier series and Hermite polynomial chaos expansion is introduced to explain the methodology. Compared with root-sumsquare and Monte Carlo methods, the proposed method is shown to be fast and accurate. [ABSTRACT FROM AUTHOR]

Transient stability (TS) and electromagnetic transient (EMT) programs are widely used simulation tools in power systems, with distinct applications but competing requirements. TS programs are fast which makes them suitable for handling large-scale networks, however, the modeling is not sufficiently detailed. On the other hand, EMT simulators are highly detailed, but limited in speed; consequently, they are used to simulate only small portions of the network. Integrating these two types of simulators generates a hybrid simulator which inherits the merits of both programs. A hybrid simulator can fulfill the modeling requirements of a large network by providing a fast as well as a detailed simulation. Establishing a connection between two different programs brings up several important issues which have been addressed, classified, and explained in this paper. An alternative integrated modeling of TS and EMT is also discussed using the concept of frequency shifting. [ABSTRACT FROM AUTHOR]

The objective of this one-institutional study was to determine the number of large-core needle biopsies (LCNB), under three-dimensional ultrasound (3D-US) validation, that are sufficient to obtain a reliable histological diagnosis of a sonographically detectable breast lesion. Over an 28-month period, 962 sonographically guided LCNB were performed under 3D-US validation to assess 962 breast lesions. All biopsies were carried out with an automated core biopsy device fitted with 14-gauge (22 mm excursion) needles. Data of 962 biopsied breast lesions were gathered. Surgical follow-up was available for 659 lesions. Breast malignancies were diagnosed by ultrasound-guided LCNB with a sensitivity of 98.2% by performing three cores per lesion. In few cases, the open surgical specimen revealed the presence of invasive carcinomas in contrast to initial LNCB-based classification as ductal carcinomas in situ (DCIS, 11 lesions), lobular carcinoma in situ (one lesion), and atypical ductal hyperpasia (one lesion). Owing to disagreement between classification based on breast-imaging and histological findings, eight of these tumours were subsequently excised. Of the lesions that were removed at the patients' requests despite benign LCNB diagnosis, two were infiltrating carcinoma and one a DCIS. We demonstrate that three 3D-US-guided percutaneous core specimens are sufficient to achieve tissue for a reliable histological assessment of sonographically detectable breast lesions and allow the detection of malignancies with high sensitivity and low rate of false-negative diagnoses. [ABSTRACT FROM AUTHOR]

This paper extends the concept of dynamic average-value modeling to power-electronic-intensive hybrid-electric vehicular power trains. Hybrid vehicles with plug-in capability are becoming increasingly important in the study of emerging smart power grids, and their simulation using digital programs has gained widespread attention. This paper demonstrates the usefulness of averaging in preserving the dynamic characteristics of the vehicular system while reducing the computational intensity of its simulation on an Electromagnetic Transients Program-type simulator. This paper presents an example of averaging for modeling, simulation, and system-level studies of a power-split gear hybrid drive-train. [ABSTRACT FROM PUBLISHER]

This task force paper presents multi-domain tools and their interfacing issues to perform simulations that require expertise in multiple areas of physics, such as electrothermal, electromechanical, electrochemical, and electromagnetic simulations, etc. Features of single multi-domain simulation tools, which are capable of simulating more than one system such as electrical chemical, mechanical, etc., are discussed. In addition, programs that are not capable of performing multi-domain simulation independently but can be interfaced with other programs to perform multi-domain simulation are also covered. Two case studies are reported where multi-domain simulations are performed in offline and real-time environments through the interfacing of more than one simulation tool. [ABSTRACT FROM PUBLISHER]

Electric power distribution systems of many commercial and industrial sites often employ variable frequency drives and other loads that internally utilize dc. Such loads are often based on front-end line-commutated rectifiers. The detailed switch-level models of such rectifier systems can be readily implemented using a number of widely available digital programs and transient simulation tools, including the Electromagnetic Transient (EMT)-based programs and Matlab/Simulink. To improve the simulation efficiency for the system-level transient studies with a large number of such subsystems, the so-called dynamic average models have been utilized. This paper presents the average-value modeling methodologies for the conventional three-phase (six-pulse) front-end rectifier loads. We demonstrate the system operation and the dynamic performance of the developed average models in discontinuous and continuous modes, as well as under balanced and unbalanced operation. [ABSTRACT FROM PUBLISHER]

This paper deals with the current state-of-the-art in interfacing issues related to real-time digital simulators employed in the simulation of power systems and power-electronic systems. This paper provides an overview of technical challenges encountered and their solutions as the real-time digital simulators evolved. Hardware-in-the-loop interfacing for controller hardware and power apparatus hardware are also presented. [ABSTRACT FROM AUTHOR]

The electromagnetic transient programs (EMTP-like tools) are based on the nodal (or modified nodal) equations that enable an efficient numerical solution and, subsequently, fast time-domain simulations. The state-variable-based simulation programs, such as Simulink, are also used for studying the dynamics of electrical systems. Both the offline and real-time versions of these two types of simulation tools are widely used by the researchers and engineers in industry and academia to study the transient phenomena and dynamics in power systems with rotating electrical machines. This paper provides a summary of the interfacing techniques that are utilized to integrate the general-purpose models of electrical machines with the rest of the power system network for these studies. The interfacing methods are broadly classified as indirect and direct approaches. The paper also describes the numerical properties as well as limitations imposed by the interfacing of the commonly used machine models that should be considered when selecting the simulation parameters and assessing the final results. [ABSTRACT FROM AUTHOR]