Waveform-level time-domain simulation comparison study of three shipboard power system architectures

Detailed waveform-level modeling and simulation of three alternative shipboard power system architectures is presented herein. The three system architectures are based on conventional 60Hz medium-voltage ac (MVAC), higherfrequency 240Hz medium-voltage ac (HFAC) and mediumvoltage dc (MVDC) technologies. To support the quantitative assessment and comparison of these three different power system architectures, each technology was modeled using a common representative, notional baseline ship. The baseline ship represents a multi-mission destroyer fitted with an 80MW next generation integrated power system (NGIPS). Modeling of each power system architecture is set forth along with simulation studies for three fault scenarios. Each of the three power system architectures was implemented within the MATLAB/ Simulink environment. Continuity of service was evaluated for each architecture along with a fault scenario using an operability metric. After a brief description of the three power system architectures and the operability metric, quantitative results are presented.Center for Electromechanic

Prognostic Value of Thyroid Hormone Ratio in Patients With Advanced Metastatic Renal Cell Carcinoma: Results From the Threefour Study (Meet-URO 14)

Background: Thyroid hormone impairment, represented as an alteration in levels of thyroid hormones and a lower fT3/fT4 ratio, has been correlated with a worse prognosis for both cancer and non-cancer patients. The role of baseline thyroid function in patients with metastatic renal cell carcinoma (mRCC) however, has not been studied yet. Materials and Methods: We recorded clinical data, baseline biochemical results, and oncological outcomes from 10 Oncology Units in Italy. We stratified patients into three groups according to the fT3/fT4 ratio value and subsequently analyzed differences in progression-free survival (PFS) and overall survival (OS) in the three groups. We also performed univariate and multivariate analyses to find prognostic factors for PFS and OS. Results: We analyzed 134 patients treated with systemic treatment for mRCC. Median PFS in the low, intermediate, and high fT3/fT4 ratio group were 7.5, 12.1, and 21.7 months respectively (p<0.001); median OS in the three groups were 36.5, 48.6, and 70.5 months respectively (p =0.006). The low fT3/fT4 ratio maintained its prognostic role at the multivariate analysis independently from IMDC and other well-established prognostic factors. The development of iatrogenic hypothyroidism was not associated with a better outcome. Conclusion: We found that baseline thyroid hormone impairment, represented by a low fT3/fT4 ratio, is a strong prognostic factor in patients treated for mRCC in first line setting and is independent of other parameters currently used in clinical practice

Improvement of Fault Tolerance in AC Motor Drives using a Digital Delta-Hysteresis Modulation Scheme

In this paper, a novel Digital Delta-Hysteresis Regulation (DDHR) scheme is proposed that allows motor drive systems to maintain relatively accurate control of phase currents in the event of the loss of all phase current sensors. within the scheme, line currents are reconstructed using knowledge of the DC-link current and switching states. the generation of switching signals is based upon traditional Delta-Hysteresis Regulation (DHR). However, modifications are made to DHR to ensure the DC-link current always contains sufficient information to reconstruct phase currents. Experimental results obtained from a vector-controlled induction machine are used to show that there is a relatively small difference between the performance of the pre- and post-fault systems

The U.S. ESRDC advances power system research for shipboard systems

In an effort to advance the research and development capabilities related to shipboard power systems, the U.S. Office of Naval Research created the Electric Ship Research and Development Consortium. This group of seven U.S. universities is working to develop near term and far term research solutions for ship power systems on the all-electric ship. This paper provides an overview of the ESRDC, its successes, resources, and activities related to education and research efforts.Center for Electromechanic

Reference design of 100 MW-h lithium/iron sulfide battery system for utility load leveling

The first year in a two-year cooperative effort between Argonne National Laboratory and Rockwell International to develop a conceptual design of a lithium alloy/iron sulfide battery for utility load leveling is presented. A conceptual design was developed for a 100 MW-h battery system based upon a parallel-series arrangement of 2.5 kW-h capacity cells. The sales price of such a battery system was estimated to be very high, $80.25/kW-h, exclusive of the cost of the individual cells, the dc-to-ac converters, site preparation, or land acquisition costs. Consequently, the second year's efforts were directed towards developing modified designs with significantly lower potential costs

Argonne National Laboratory Reports

This report covers the first year in a two-year cooperative effort between Argonne National Laboratory and Rockwell International to develop a conceptual design of a lithium alloy/iron sulfide battery for utility load leveling. A conceptual design was developed for a 100 MW-h battery system based upon a parallel-series arrangement of 2.5 kW-h capacity cells. The sales price of such a battery system was estimated to be very high, $80.25/kW-h, exclusive of the cost of the individual cells, the dc-to-ac converters, site preparation, or land acquisition costs. Consequently, the second year's efforts were directed towards developing modified designs with significantly lower potential costs