The Experts below are selected from a list of 66252 Experts worldwide ranked by ideXlab platform
Keith Corzine - One of the best experts on this subject based on the ideXlab platform.
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Extended Operation of flying capacitor multilevel inverters
IEEE Transactions on Power Electronics, 2006Co-Authors: Jing Huang, Keith CorzineAbstract:Recent research in flying capacitor multilevel inverters (FCMIs) has shown that the number of voltage levels can be Extended by changing the ratio of the capacitor voltages. For the three-cell FCMI, four levels of Operation are expected if the traditional ratio of the capacitor voltages is 1:2:3. However, by altering the ratio, the inverter can operate as a five-, six-, seven-, or eight-level inverter. According to previous research, the eight-level case is referred to as maximally distended (or full binary combination schema) since it utilizes all possible transistor switching states. However, this case does not have enough per-phase redundancy to ensure capacitor voltage balancing under all modes of Operation. In this paper, redundancy involving all phases is used along with per-phase redundancy to improve capacitor voltage balancing. It is shown that the four- and five-level cases are suitable for motor drive Operation and can maintain capacitor voltage balance under a wide range of power factors and modulation indices. The six-, seven-, and eight-level cases are suitable for reactive power transfer in applications such as static var compensation. Simulation and laboratory measurements verify the proposed joint-phase redundancy control.
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Extended Operation of flying capacitor multilevel inverters
IEEE Industry Applications Society Annual Meeting, 2004Co-Authors: Jing Huang, Keith CorzineAbstract:Recent research in flying capacitor multilevel inverters (FCMIs) has shown that the number of voltage levels can be Extended by changing the ratio of the capacitor voltages. For the three-cell FCMI, four levels of Operation are expected if the traditional ratio of the capacitor voltages is 1:2:3. However, by altering the ratio, the inverter can operate as a five-, six-, seven-, or eight-level inverter. According to previous research, the eight-level case is referred to as maximally distended (or full binary combination schema) since it utilizes all possible transistor switching states. However, this case does not have enough per-phase redundancy to ensure capacitor voltage balancing under all modes of Operation. In this paper, redundancy involving all phases is used along with per-phase redundancy to improve capacitor voltage balancing. It is shown that the four- and five-level cases are suitable for motor drive Operation and can maintain capacitor voltage balance under a wide range of power factors and modulation indices. The six-, seven-, and eight-level cases are suitable for reactive power compensation in applications such as static var compensation. Simulation and laboratory measurements results verify the proposed joint-phase redundancy control.
P Fuentes - One of the best experts on this subject based on the ideXlab platform.
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Extended Operation for lung cancer invading the superior vena cava
European Journal of Cardio-Thoracic Surgery, 1994Co-Authors: P Thomas, P E Magnan, G Moulin, Roger Giudicelli, P FuentesAbstract:Between 1981 and 1991, 845 patients were operated on for right lung cancer. Among them, 50 (6%) had a tumor invading the superior vena cava (SVC). Fifteen patients (14 men and 1 woman, mean age: 58 years) underwent radical resection with concomitant vascular reconstruction. Two patients presented with a superior vena caval syndrome. The SVC was invaded by direct extension from the tumor (n = 11) or by paratracheal nodal involvement (n = 4). The patients required pneumonectomy (n = 13) or upper lobectomy (n = 2), with lateral (n = 11) or circumferential resection (n = 4) of the SVC. The venous pathway was repaired by direct suture (n = 9), prosthetic patch (n = 2) or polytetrafluoroethylene (PTFE) graft (n = 4). Tumor resection was considered macroscopically complete in 12 patients (80%). One patient died postoperatively (7%) and non-fatal complications occurred in 3 (20%). Early patency of the four grafts was assessed by phlebography. In the late course, pulmonary embolism occurred in two patients and Extended superior vena caval thrombosis in one; the overall clinical patency rate was 75.7% at 1 and 5 years. Two patients (13.3%) experienced mediastinal recurrence; the overall survival rates at 1 year, 2 years and 5 years were, respectively, 46.7%, 32% and 24% (median: 8.5 months). We conclude that Extended resection for lung cancer invading the SVC, when feasible, is justified given the effective control of the primary tumor thereby provided, with an acceptable operative risk.
Jing Huang - One of the best experts on this subject based on the ideXlab platform.
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Extended Operation of flying capacitor multilevel inverters
IEEE Transactions on Power Electronics, 2006Co-Authors: Jing Huang, Keith CorzineAbstract:Recent research in flying capacitor multilevel inverters (FCMIs) has shown that the number of voltage levels can be Extended by changing the ratio of the capacitor voltages. For the three-cell FCMI, four levels of Operation are expected if the traditional ratio of the capacitor voltages is 1:2:3. However, by altering the ratio, the inverter can operate as a five-, six-, seven-, or eight-level inverter. According to previous research, the eight-level case is referred to as maximally distended (or full binary combination schema) since it utilizes all possible transistor switching states. However, this case does not have enough per-phase redundancy to ensure capacitor voltage balancing under all modes of Operation. In this paper, redundancy involving all phases is used along with per-phase redundancy to improve capacitor voltage balancing. It is shown that the four- and five-level cases are suitable for motor drive Operation and can maintain capacitor voltage balance under a wide range of power factors and modulation indices. The six-, seven-, and eight-level cases are suitable for reactive power transfer in applications such as static var compensation. Simulation and laboratory measurements verify the proposed joint-phase redundancy control.
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Extended Operation of flying capacitor multilevel inverters
IEEE Industry Applications Society Annual Meeting, 2004Co-Authors: Jing Huang, Keith CorzineAbstract:Recent research in flying capacitor multilevel inverters (FCMIs) has shown that the number of voltage levels can be Extended by changing the ratio of the capacitor voltages. For the three-cell FCMI, four levels of Operation are expected if the traditional ratio of the capacitor voltages is 1:2:3. However, by altering the ratio, the inverter can operate as a five-, six-, seven-, or eight-level inverter. According to previous research, the eight-level case is referred to as maximally distended (or full binary combination schema) since it utilizes all possible transistor switching states. However, this case does not have enough per-phase redundancy to ensure capacitor voltage balancing under all modes of Operation. In this paper, redundancy involving all phases is used along with per-phase redundancy to improve capacitor voltage balancing. It is shown that the four- and five-level cases are suitable for motor drive Operation and can maintain capacitor voltage balance under a wide range of power factors and modulation indices. The six-, seven-, and eight-level cases are suitable for reactive power compensation in applications such as static var compensation. Simulation and laboratory measurements results verify the proposed joint-phase redundancy control.
Salvatore M Oriti - One of the best experts on this subject based on the ideXlab platform.
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test program for stirling radioisotope generator hardware at nasa glenn research center
12th International Energy Conversion Engineering Conference, 2014Co-Authors: Edward J Lewandowski, Gary S Bolotin, Salvatore M OritiAbstract:Stirling-based energy conversion technology has demonstrated the potential of high efficiency and low mass power systems for future space missions. This capability is beneficial, if not essential, to making certain deep space missions possible. Significant progress was made developing the Advanced Stirling Radioisotope Generator (ASRG), a 140-W radioisotope power system. A variety of flight-like hardware, including Stirling convertors, controllers, and housings, was designed and built under the ASRG flight development project. To support future Stirling-based power system development NASA has proposals that, if funded, will allow this hardware to go on test at the NASA Glenn Research Center. While future flight hardware may not be identical to the hardware developed under the ASRG flight development project, many components will likely be similar, and system architectures may have heritage to ASRG. Thus, the importance of testing the ASRG hardware to the development of future Stirling-based power systems cannot be understated. This proposed testing will include performance testing, Extended Operation to establish an extensive reliability database, and characterization testing to quantify subsystem and system performance and better understand system interfaces. This paper details this proposed test program for Stirling radioisotope generator hardware at NASA Glenn. It explains the rationale behind the proposed tests and how these tests will meet the stated objectives.
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Extended Operation of stirling convertors at nasa glenn research center
2013Co-Authors: Salvatore M OritiAbstract:NASA Glenn Research Center (GRC) has been supporting development of free-piston Stirling conversion technology for spaceflight electrical power generation since 1999. GRC has also been supporting the development of the Advanced Stirling Radioisotope Generator (ASRG) since 2006. A key element of the ASRG project is providing life, reliability, and performance data for the Advanced Stirling Convertor (ASC). The Thermal Energy Conversion branch at GRC is conducting Extended Operation of several free-piston Stirling convertors. The goal of this effort is to generate long-term performance data (tens of thousands of hours) on multiple units to build a life and reliability database. Currently, GRC is operating 18 convertors. This hardware set includes Technology Demonstration Convertors (TDCs) from Infinia Corporation, of which one pair (TDCs #13 and #14) has accumulated over 60,000 hr (6.8 years) of Operation. Also under test are various Sunpower, Inc. convertors that were fabricated during the ASC development activity, including ASC-0, ASC-E (including those in the ASRG engineering unit), and ASC-E2. The ASC-E2s also completed, or are in progress of completing workmanship vibration testing, performance mapping, and Extended Operation. Two ASC-E2 units will also be used for durability testing, during which components will be stressed to levels above nominal mission usage. Extended Operation data analyses from these tests are covered in this paper.
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Extended Operation of stirling convertors at nasa glenn research center
International Energy Conversion Engineering Conference (IECEC 2011), 2011Co-Authors: Salvatore M OritiAbstract:Glenn Research Center (GRC) is supporting life and reliability database for free-piston Stirilng conversion via Extended convertor Operation Ongoing convertor Operation: 18 convertors (4 TDCs from Infinia, 14 ASCs from Sunpower). 350,000 total convertor hours of Operation. 218,000 on Infinia units and 132,000 on Sunpower units. Demonstrating steady convertor performance requires precise maintenance of operating conditions. Sources of disruption : Investigative tests: Varying operating frequency, hot-end temp, cold-end temp. Hot end control method: Constant heat input mode requires more user-adjustment than constant temperature mode. Long-term transients in hot end insulation were observed. Support facility: Open-bath circulator fluid concentration drifting. Nuisance shutdowns (instrumentation failure, EMI, power outages). Ambient temperature fluctuations due to room HVAC.
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stirling convertor Extended Operation testing and data analysis at glenn research center
Seventh International Energy Conversion Engineering Conference (IECEC), 2010Co-Authors: Peggy A Cornell, Edward J Lewandowski, Salvatore M Oriti, Scott D WilsonAbstract:Extended Operation of Stirling convertors is essential to the development of radioisotope power systems and their potential use for longduration missions. To document the reliability of the convertors, regular monitoring and analysis of the Extended Operation data is particularly valuable, allowing us to better understand and quantify long-life characteristics of the convertors. Furthermore, investigation and comparison of the Extended Operation data to baseline performance data provides an opportunity to understand system behavior should any off-nominal performance occur. Glenn Research Center (GRC) has tested 16 Stirling convertors under 24-hr unattended Extended Operation, including four that have operated in a thermal vacuum environment and two that are operating in the Advanced Stirling Radioisotope Generator Engineering Unit. Ten of the sixteen convertors are the Advanced Stirling Convertors (ASC) developed by Sunpower, Inc. with GRC. These are highly efficient (conversion efficiency of up to 38 percent for the ASC-1), low-mass convertors that have evolved through technologically progressive convertor builds. Six convertors at GRC are Technology Demonstration Convertors from Infinia Corporation. They have achieved greater than 27 percent conversion efficiency and have accumulated over 185,000 of the total 265,000 hr of Extended Operation at GRC. This paper presents the Extended Operation testing and data analysis of free-piston Stirling convertors at NASA GRC as well as how these tests have contributed to the Stirling convertor s progression toward flight.
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stirling convertor Extended Operation testing and data analysis at grc
7th International Energy Conversion Engineering Conference, 2009Co-Authors: Peggy A Cornell, Edward J Lewandowski, Salvatore M Oriti, Scott D WilsonAbstract:This paper focuses on Extended Operation testing and data analysis of free-piston Stirling convertors at the NASA Glenn Research Center (GRC). Extended Operation testing is essential to the development of radioisotope power systems and their potential use for long duration missions. To document the reliability of the convertors, regular monitoring and analysis of the Extended Operation data is particularly valuable; allowing us to better understand and quantity the long life characteristics of the convertors. Further, investigation and comparison of the Extended Operation data to baseline performance data provides us an opportunity for understanding system behavior should any off-nominal performance occur. GRC currently has 14 Stirling convertors under 24-hour unattended Extended Operation testing, including two operating the Advanced Stirling Radioisotope Generator Engineering Unit (ASRG-EU). 10 of the 14 Stirling convertors at GRC are the Advanced Stirling Convertors (ASC) developed by Sunpower, Incorporated. These are highly efficient (up to > 33.5% conversion efficiency), low mass convertors that have evolved through technologically progressive convertor builds. The remaining four convertors at GRC are Technology Demonstration Convertors (TDC) from Infinia Corporation. They have achieved> 27% conversion efficiency and have accumulated over 178,000 of the total 250,622 hours of Extended Operation currently at GRC. A synopsis of the Stirling convertor Extended Operation testing and data analysis at NASA GRC is presented in this paper, as well as how this testing has contributed to the Stirling convertor's progression toward flight.
Chuanbin Guo - One of the best experts on this subject based on the ideXlab platform.
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maxillary fronto temporal approach for removal of recurrent malignant infratemporal fossa tumors anatomical and clinical study
Journal of Cranio-maxillofacial Surgery, 2014Co-Authors: Yuxing Guo, Chuanbin GuoAbstract:Abstract Purpose For recurrent malignant tumors occurring in the infratemporal fossa, it is difficult to select a proper surgical approach. We explore the efficiency of a new approach for removal of recurrent malignant tumors involving the infratemporal fossa based on the measurement on three-dimension CT, observation of six cadaveric specimens, and our surgical experience. Materials and methods The distances between the surgical landmarks in the infratemporal fossa were measured using CT data to determine the safe distance. And anatomy observation was examined on 6 formalin-fixed cadaveric specimens. Data from seven patients with recurrent malignant infratemporal fossa tumors were retrospectively analyzed. Results The mean distance of the medial pterygoid plate from the zygoma was 52.12 mm. The maxillary artery can be found between the deep surface of the condyle and the sphenomandibular ligament, with mean distance of 8.25 ± 3.22 mm to the inferior border of the capsule of the temporomandibular joint. All tumors got gross resection using the maxillary-fronto-temporal approach with minor complication. Conclusions The advantages of the new approach include adequate protection of facial nerve with Extended Operation field; the exposed temporal muscle could be used to fill the dead space. This technique is especially useful to remove recurrent malignant infratemporal tumors safely.
