Top PDF Development and Characterization of Hybrid SiC Power Devices.

Development and Characterization of Hybrid SiC Power Devices.

Development and Characterization of Hybrid SiC Power Devices.

Higher blocking voltages and higher switching frequencies can be achieved by de- signing devices using different semiconductor materials. Wide bandgap (WBG) semicon- ductors like the 4H-SiC have attracted the most attentions due to its superior material properties over Si and large wafer size suitable for power device constructions [77]. The ten times higher electric field strength in the SiC allows devices to be designed for much higher blocking voltages. For examples, 10 kV and 15 kV SiC MOSFETs, 15 kV SiC IGBT and 15 kV SiC GTO have been reported in [22][86]. Not only the blocking volt- age is getting much higher, but also the switching frequency is greatly improved due to much lower dynamic losses. To evaluate the superior performances of the high voltage SiC devices, the switching frequency times operation voltage (MHz-V) can be used as a figure of merit (FOM) for the high voltage power devices. The high power Si devices like IGBT or ETOs usually operate below the 5 MHz-V limit. In [54], 10 kHz switching of 10 kV SiC MOSFET and 15 kV SiC IGBT are demonstrated at 5.5 kV, and in [88] the efficiency of a boost converter based on 15 kV SiC MOSFET was evaluated under 20 kHz and 40 kHz switching frequency with 6 kV operation voltage. So for high voltage SiC MOSFETs, the operation area can be 20 times or even 40 time larger than Si as illustrated in Fig. 4.1. This makes SiC MOSFETs very attractive for medium voltage medium frequency applications such as the solid state transformer [88].
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Characterization of the developmental alloys was carried using SEM, EDS, TEM, and XRD analysis in order to evaluate grain size, dislocation microstructure, matrix microstructure and composition, and nanoparticle size, dispersion, and composition. The presented data only reflects particles observed in the images collected through the analysis techniques utilized; this only represents a very small sample of the microstructure and nanoparticle dispersion in the consolidated alloy. The resolution of SEM limits observations to particles of 10nm or larger and scanning electron microscopy only reveals the particle dispersion on the surface of the alloy; particles fully obscured within the alloy matrix are not properly represented as they are not observed or counted at all and particles partially obscured result in inaccurate calculated area estimates. A combination of SEM, EDS, TEM (EFTEM), XRD, and atom probe analyses would be necessary to form a comprehensive imaging record of as fabricated and irradiated microstructure, nanoparticle size, dispersion, and composition for 18CrODS and 9Cr ODS.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

impairment decline) compared to youth who were non-ADHD at baseline and either non- ADHD or subthreshold ADHD at follow-up (4% and 9% decline in overall impairment, respectively). Thirty three percent of youth who were subthreshold at baseline remained in that category at follow-up and 15%-27% of those individuals showed significant decline in at least one domain of functioning and 47% declined in overall impairment at follow-up. Conclusions: The findings show the importance of examining symptom and impairment constructs separately in the consideration of their unique contributions to ADHD and subthreshold ADHD diagnoses and of acknowledging the need to examine nuanced changes in diagnostic status during development; especially functional declines. These findings may be relevant to efforts to intervene earlier in childhood and to help identify high-risk individuals who may be good candidates for targeted interventions. Key words: Attention Deficit Hyperactivity Disorder, Subthreshold ADHD, symptom and impairment trajectories, predictors of impairment. Abbreviations: RCI, reliable change index; ADHD, attention-deficit/hyperactivity disorder; DISC-IV, Diagnostic Interview Schedule for Children version IV; SDQ, Strengths and Difficulties
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

countries and maximize the effectiveness of donor aid. The Paris Declaration is based on the recognition that partner country should take ownership of development strategies. A country partner has ownership when it takes the lead in determining the goals and priorities of its own development and set the agenda for how they are to be achieved. Strengthening the country's ownership represents a shift of power in the way aid relationship worked in the past, while underlining the need for mutual accountability (OECD, 2009). With strong ownership, the prospects for progress against other Paris Declaration principles improve. If partners “own” priorities, plans and programs, they are more likely to exercise effective leadership in getting donors to align to national
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

individuals for committees, etc.; provide specific agenda items for staff meetings for the coach to report progress and acknowledgement of teachers; and understand that change will take time as the coach forges new relationships with teachers. The third strategy is the principal must be accessible as a resource to the coach. As a resource the principal assists the coach in generating ideas for dealing with conflicts among staff members, brainstorming ideas for scheduling conflicts, and discussing professional development opportunities and ideas for some or all teachers. The fourth strategy is the principal provides access to both human and fiscal resources. Without providing coaches with the necessary resources, a principal can set up an instructional coaching program for failure. Resources come in a variety of forms such as student data, time, space, contacts at other schools or other levels within the school system, secretarial assistance, technology, and professional development. The fifth strategy is the principal maintains the instructional coaching focus for the instructional coach. The principal must only allow a coach to be utilized for activities that are related to teaching and learning. Activities related to managerial and operational activities such as student discipline, textbook inventory, or buses cannot be part of an instructional coaching program. The sixth strategy for a
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Peer review. The purpose of peer review is to establish credibility of the analysis process by determining congruency of coding and production of emergent themes from raw data and subsequent interpretations. 206 The RA who served as the note taker was also a peer reviewer for the first phase of the data analysis process. Using an a priori code list, the RA independently coded the first AA with stroke and PT transcripts in their entirety and a five page portion of the second PT transcript, all of which were compared against the PI’s findings of the same data set. During the initial process of open coding, there was an attempt to have 70% agreement in codes. Percent agreement between two coders ranging from 70 to 90 is documented and deemed appropriate in qualitative research. 207,208 Initial intercoder reliability (ICR) was established and thereafter, the RA and PI discussed commonalities and discrepancies during this initial process, seeking 100% agreement on any code discrepancies. The second peer review activity consisted of an AA PT unfamiliar with the study and PI independently coding all of the transcripts using a codebook. Discrepant codes were discussed until 100% agreement was achieved. The PI updated the codebook categories, subcategories, and definitions after discussing each transcript before proceeding to the next. The third peer review activity consisted of two qualitative researchers serving as committee members checking the process of node development in NVivo 10, 209 data reduction, and theme development. This phase of the data analysis process was discussed between each qualitative researcher and PI until there was agreement of the resultant themes.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

While many advances were made in lighting technology over time, the continued production of solid-state lighting materials containing rare earths is in jeopardy. It is projected that rare-earth oxide demand will surpass the supply of rare-earth oxide materials. Furthermore, China controls approximately 97% of the global market. The export of these materials will also decrease due to China’s own growing demand. This supply and demand situation for rare-earth materials may eventually cause lighting research to focus more and more on the development of rare-earth free lighting materials and/or organic light emitting devices (OLEDs) 6 . A 2011 report by Philips Lighting Company, showed the critical need for rare-earths oxides to sustain the global demand for lighting materials. The main rare earth ions needed for phosphor materials are
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Attention deficit/hyperactivity disorder (ADHD) is a behavioral disorder that first emerges in childhood and affects performance in the classroom, functional abilities at home, and development of peer relationships. It is a persistent pattern of inattention and/or hyperactivity/impulsivity that occurs across settings (American Psychological Association, 2000). ADHD affects nearly 10% of children throughout the United States (CDC, 2007). Children with genetic disorders, such as fragile X syndrome (FXS) are at a high risk for developing ADHD. Children with FXS often have many behavioral and cognitive concerns that arise amongst an array of developmentally abnormal features (Farzin et al., 2006). Many children with FXS are affected with irregular emotional and physiological reactivity, hyperactivity, impulsivity, inattention, and problematic patterns of emotional regulation (Hatton et al., 2003; Hatton et al., 2009; Roberts et al., 2009). These behavioral traits emerge early in development and may represent vulnerability for the manifestation of secondary conditions. The developmental trajectory of ADHD symptoms has been documented in typically developing populations, but has not been thoroughly examined in FXS. The recognition of this complex development of
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

The study that was used as a basis for the development of this thesis provided results of the performance for the GPU implementation compared to a CPU. That study achieved a significant improvement using a GPU and results were given for a comparison of 7 million reads processed in 0.432 seconds, which achieves 16.2 million reads per second performance [4]. While this method of performance measurements indicate a 3.78x improvement of the DSP implementation described in this thesis, it fails to account for the difference in architectures used. The hardware described in that study used 2 NVidia Tesla C2050 GPUs, which each contain 448 cores and consume a maximum of 247 watts. NVidia lists the running power consumption of a single GPU at 238 watts [18]. Accounting for the 2 GPUs used, the mapped bases per watt-second of the GPU implementation is 676,742.83. Compared to the DSP, which achieves 3,155,556.73 mapped bases per watt-second, there is a 4.66x improvement over the GPU. The power consumption for the performance metric for the GPU must be estimated instead of measured, only the running power for the GPUs was used in the calculations. More power would be consumed with the controlling CPU needed to operate the GPU, which would decrease the performance of the GPU a small degree more than indicated.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Toch composed one work for military band: Spiel für Blasorchester, Op. 39 (1926), which has been the subject of previous scholarship. This document provides a history and analysis of his remaining works for winds: Miniatur-Ouvertüre, Five Pieces for Wind Instruments and Percussion, Op. 83, and Sinfonietta for Wind Instruments and Percussion, Op. 97. Since these works encompass more than thirty-years of his career, some compositional style development is found; however, Toch’s broad treatment of melody, harmony, orchestration, and form are strikingly consistent. Each work is melodically driven and doesn’t conform fully to traditional forms. The harmonic flavor of each work is determined by melodic content. Found often are areas of full chromaticism, non-functional triads, and other ambiguous harmonies.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

downregulation of anti-cancerous and inflammatory genes, and the absence of APN- induced downregulation of secretion of pro-inflammatory cytokines. Similarly, a recent study by Moon et al. precisely examined the role of adiponectin on CRC in the settings of obesity 40 . They found that mice fed a high fat diet had larger tumors than those fed a low fat diet but adiponectin administration reversed this effect 40 . Adiponectin treatment also suppressed angiogenesis in tumors as indicated by fewer dense microvessel areas and a reduction in mRNA expression of VEGF 40 . While IL-12, a cytokine that has been associated with anti-tumor properties was increased following adiponectin treatment, in contrast to the findings of Saxena et al., serum cytokine (IFN-γ, IL-2, IL-4, IL-5, IL-10 and TNF-α) levels were unchanged 40 . To further address the mechanisms for this effect they completed a series of in vitro studies and found that adiponectin directly controls malignant potential (cell proliferation, adhesion, invasion and colony formation) and regulates metabolic (AMPK/S6), inflammatory (STAT3/VEGF) and cell cycle (p21/p27/p53/cyclins) signaling pathways in both mouse and human colon cancer cells lines 40 . These results highlight the importance of adiponectin in the growth and development of CRC, inflammatory processes, and suggest that the adiponectin deficiency that is a characteristic of obesity plays an important role in the biochemistry of CRC.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Much of the work done thus far regarding antibiotic contamination has concentrated on the development and proliferation of genetic antibiotic resistance in bacteria (Daughton and Ternes, 1999; Sengeløv et al. 2003, Kim and Aga, 2007). While antibiotic resistance is perhaps the most significant human health threat of the 21st century, another large area of concern is that of ecological impact. There have been a number of laboratory-based toxicological studies, most of which suggest that antibiotics in the environment pose a "potential" ecological problem. Wilson et al. (2003) found that antibiotics reduces algal genus richness and final biomass in environmental communities. Eguchi et al. (2004) found that antibiotics reduced cell growth and that some compounds acted synergistically against eukaryotic algae. Kim and Carlson, (2007) reported high concentrations of antibiotics in freshwater stream sediments. There are numerous other studies suggesting potential problems, such as Liu et al. (2011a), (Liu et al. 2011b), Weber et al. (2011), Hagenbuch and Pinckney, (2012), and Pinckney et al. (2013). A number of studies that have determined that heavily-impacted environments have ecological issues that extend through trophic levels beyond prokaryotes. For example, Wollenberger et al. (2000) found that Daphnia magna are subject to reduced
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Clyde disclosed he did consider leaving when the business major was not working out, but ultimately decided to stay, discussing both support and situation in making his retention decision. He felt the people are “genuinely interested in seeing me succeed, it’s more than just being a statistic or another passing student… they actually care about your career and want you to do well in life and that’s ultimately what kept me here...” Clyde’s comment is consistent with the construct of “institutional commitment to the welfare of students” proffered by Braxton, Hirschy, and McClendon (2004) in their revision of Tinto’s (1975, 1986, 1993) theory on student departure focused on students at residential colleges and universities. The construct is defined as “an abiding concern for the growth and development of students” (Braxton and Hirschy, 2005, p. 70). The authors argue that initial commitment to the institution affects perceptions of several institutional
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

To better understand the interaction between these advanced materials, each material was implemented into FRAPCON 3.4, the preferred fuel performance code of the NRC; additionally, the material properties and the heat transfer physics associated with a gas coolant were incorporated. The implementation of carbide within FRAPCON required the development of material models that described not only the thermophysical properties of UC, such as thermal conductivity and thermal expansion, but also models for the swelling, densification, and fission gas release associated with the fuel’s irradiation behavior.
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Integration of HfO2 on Si/SiC heterojunctions for the gate architecture of SiC power devices

Integration of HfO2 on Si/SiC heterojunctions for the gate architecture of SiC power devices

The physical and electrical properties of silicon car- bide (SiC), including its wide band gap (3.26 eV ), high critical electric field (3 M V /cm) and thermal conduc- tivity (3.7 W/cmK), make it an attractive material for high frequency, high power devices. Twenty years of material development has seen many of the processing techniques mature and the quality of the substrates im- prove significantly, to a point where the substrates sup- plied today achieve a defect density low enough to fab- ricate electronic devices. Commercial SiC Schottky bar- rier diodes and junction gate field-effect transistors 1 are
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Tissue engineers have extensively studied the type of cells that should be utilized when developing replacement blood vessels, while also providing a list of criteria that the replacement vessel should meet. In a general sense, to say that one has effectively created a replacement, the replacement must effectively mimic the native artery not only biologically but also in its response to mechanical load. Though the mechanical responses of some arteries have been studied extensively, not all major arteries have been mapped out and described in terms of their biomechanical properties. In particular, the properties of renal arteries have not been actively studied, resulting in a paucity of experimental data. Since such baseline data is necessary for the development of replacement renal artery constructs, the work described herein presents the results from recent studies focusing on quantifying the behavior of porcine renal arteries.
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SiC power devices for applications in hybrid and electric vehicles

SiC power devices for applications in hybrid and electric vehicles

operating point is not appropriate for SiC based converters. Therefore, a more adaptive approach to dead-time setting should be utilized in SiC based converter to ensure a good overall performance [5]. With powerful controllers used in automotive power electronics this is not considered an issue for implementation. Fig. 2 shows the variation of efficiency as a function of input power at different dead-times (300 ns, 500 ns, and 700 ns) for the SiC converter. The results demonstrates that even at this high frequency of 100 kHz the efficiency is over 98% for powers above 3 kW to approximately 9 kW.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

The power Schottky diode model is a simple physics-based model comprised of a voltage controlled current source, a temperature dependent drift region resistance and a nonlinear capacitance. A detailed parameter extraction procedure for a simple physics- based power SiC Schottky diode model is presented. The proposed parameter extraction procedure includes the extraction of doping concentration, active area and thickness of drift region, which are needed for the proposed physics-based power Schottky diode model. The main advantage is that this procedure does not require any knowledge of device fabrication. The only measurements required for the parameter extraction are a simple static I-V characterization and C-V measurements. Validity of the approach is verified by comparison of simulated and experimental results at temperatures from 25º C to 175º C for four different devices from two different manufacturers which are shown in the first paragraph. Inductive switching validation also shows that the model has a fairly good match with experiments. This means that the model presented in this dissertation is general and can be used for devices with widely different voltage and current ratings.
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Development of SiC heterojunction power devices

Development of SiC heterojunction power devices

The need for efficient energy conversion is clear then; the efficient switching of energy from one form to another is an issue that impacts on all the green technologies that will become so prevalent over the next 50 years. But what makes an inverter, a rectifier or a DC-DC converter efficient? Figure 2.2 shows the simplest inverter circuit, where the application of a trigger to transistors 1 and 4 allow current flow one way through the load, whilst the triggering of 2 and 3 forces it through in the opposite direction. The use of pulse width modulation and some smoothing circuitry offers the opportunity to reduce the harmonic frequencies in this circuit after smoothing, hence creating an AC signal such as the dotted line in Figure 2.2. The peak-to-peak amplitude of the resulting A.C. signal is twice the DC current, whilst the frequency is controllable by the devices’ switching speed. The diodes in this circuit prevent any inductive reverse current from the load damaging the transistors. Further detail on this and more complex converters may be found in [29].
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

In the 1950’s, social scientists saw a need to quantify the methods of their sciences, such as sociology and anthropology. Thus many adopted terms and concepts from graph theory to help describe problems they faced. They used these ideas to help cre- ate models as well as analyze collected empirical data, linking graph theoretical ideas with social ideas such as “status, influence, cohesiveness, social roles, and identities in social networks,” [5] page 3. Around the same time, graphs became an accepted model for means of disease and information transmission. Furthermore, it was around this time that the notion of random graphs saw its early developments. This new approach saw graphs as stochastic, or probabilistic, objects rather than deterministic. All these events thus produced a surge of interest in the new field of network science. [5] chapter 1. Before any further discussion of the historical development of network science, it is important to introduce several basic concepts from graph theory. For a complete introduction to graph theory, see e.g. Diestel’s book Graph Theory [9].
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