For electric vehicle (EV) applications, Toyota reported a new SiC power converter for use in automotive power control units (PCU). With this new converter, the fuel efficiency improves by 10% compared with the Si-based EV. This new technology also enables 80% size reduction in the PCU with respect to the previous version. For medium voltage applications, Cree, Inc. recently developed 10 kV, 120 A SiC power MOSFETs and 1700V Schottky diodes which can replace conventional IGBTs and Si-based diodes. At 20 kHz, the switching loss of a SiC MOSFET is 18 times lower than that of a Si-based IGBT and the conduction loss is almost half . In the case of GaN powerdevices, the product availability is less than that of SiC, especially in high voltage applications due to its inherent material characteristic (high electron mobility) and more expensive manufacturing cost. However, GaN devices are more suitable for 600 V or less voltage level and lower power applications than SiC due to its high electron mobility and size advantage. One of the GaN device manufacturers, Efficient Power Conversion (EPC) Corporation released a 300 V, 2.7 A enhanced mode power transistor, which can be applied in various applications where high frequency switching is essential. Regarding concern for the price of WBG devices, they are expected to be cheaper than Si devices in 2016 and this will dramatically boost the transition from Si devices to WBG devices. For applications lower than 200 V, there are abundant options of GaN devices that can be applied to the MHz-level DC- DC converters.
Abstract—The fast switching speeds and low specific conduction losses of wide band-gap semiconductors allow the realisation of high-frequency, highpower-density switching converters with dramatically reduced passive component requirements compared to Silicon technology. However, careful attention must be paid to switching cell design to mitigate the effects of circuit parasitics and fast voltage transitions which would otherwise limit the attainable switching speed and lead to increased levels of EMI. This paper presents a modular, power- cell solution which allows the creation of any two-level topology converter. The cell structure enables fast switching of wide bandgap semiconductor devices while allowing highpower converters to be fabricated using multiple, smaller commutation cells. Close integration of semiconductor dies, decoupling capacitors, gate drives and an output filter with a single ceramic substrate to act as the thermal path allows dramatic increases in power density without compromising converter performance. 1
The understanding of the bulk morphology of materials is important in the pharmaceutical industry and has an impact on the material’s solubility, stability, and therapeutic properties. 2 One example, reported by Kato et al., showed that the three forms of phenobarbital, a widely used anti-convulsant, had differing dissolution rates with the metastable form, form II-Ba, having the highest. 3 In this aspect, it is important to understand the correlation between the bulk properties and the crystal packing of compounds, such as in the work of Corvis et al. 4 The two polymorphic forms of glutaric acid, a common co-crystallizing agent for pharmaceuticals, were studied. They examined the bulk properties of the α-form including its thermal properties and high resolution PXRD. Through study of these bulk properties, they were able to propose a crystal structure for this elusive polymorph at higher temperatures. 4 They also studied the thermal properties to gain a better understanding of the high temperature solid-to-solid phase transition between the two forms.
When isolated topologies are utilized, a high voltage gain is traditionally achieved by manipulating the transformer’s turns ratio, the pulse width modulation duty ratio or phase-angle shift. The duty ratio of high-frequency switchingdevices is often con- sidered as one design freedom while the turns ratio of transform- ers is another –. When both are employed to achieve a high voltage conversion ratio, it is termed the two degrees of freedom (2DoF) design , , . Furthermore, soft switching can also be a useful feature when an active or passive clamping circuit is implemented –. An active clamping cir- cuit consists of one active switching device and one clamping capacitor, while a passive clamping circuit uses some passive switchingdevices (e.g., diodes) for the same purpose. In theory, the leakage inductance is proportional to the square of the turns ratio . As a result, a very high turns ratio is generally avoided in the transformer design since it can reduce the efficiency of the transformer. A typical topology of high step-up converters uses only one switching device ,  while their converter ratings are low. Due to the size of capacitors, the power den- sity of these converters decreases as the voltage gain increases –. In the literature, some high step-up conversion ra- tios are also reported by combining the features of turns ratio, multilevel and duty ratio in the converter design –. For instance, paper  integrates a coupled inductor with a switch- ing capacitor in the high step-up converter using one switching device. The input-parallel output-series structure can also pro- vide a high voltage gain and a highpower level , . In paper , coupled inductors are used to achieve a high voltage gain but electrical isolation is absent. Alternatively, the use of a cascaded converter structure can provide a high voltage gain , . However, the topology in  is limited in converter power ratings due to the high current in the switchingdevices. In order to increase the power level, a modular multilevel con- verter is presented in  but it can only regulate the duty ratio and cell number (i.e., 2DoF). Clearly, these reported topologies do not provide electrical isolation and sufficient flexibility for further expansion.
Field Programmable Gate Arrays have been used for high performance computing with a great success at large performance speedups. The processors are capable of being reconfigured with a new design to meet multiple needs and are efficient at parallel tasks within the limitations of the hardware blocks available on a FPGA processor. Generally FPGAs are more complex to use, as a specific design must be mapped first before being used as a coprocessor. Often times this can be a daunting task that is quite difficult. Any modifications may cause the entire design to have to be modified. With these limitations, they are still capable of huge performance gains within a certain scope of applications. Several studies were done to explore their use within short read mapping applications.
Instead of using oil-immersed contact and complicated mechanical drive, a vacuum switch and bi- stable electromechanical actuator were used. These vacuum switches had the advantages of highpower handling capability and long life, thus, suitable for the use of the selector. The proposed diverter, consisting of two solid-state switches, was to be connected between each of the selector output leads and in parallel with those two solid-state switches. A faster form of GTO assisted tap changer with the advantage of reduced transformer outages. The speed of the intended vacuum switch moving is now controllable, since fatigue in the stainless steel bellows is the prime limitation, and reverts to fast operation during a system fault.
Research question 2, manuscript 1, examined the predictors (or risk variables) of more severe forms of impairment at baseline, to see if they were similar for youth with ADHD, youth with subthreshold ADHD, and youth without ADHD. The outcome variable, “severe” (abnormal/high) impairment was met if at least two functional domain items were endorsed as a “medium amount” or one item was endorsed as a “great deal.” Five of the functional impairment questions above were summed and a total impairment score was treated dichotomously, with “severe impairment present” = 1, and, “absent” = 2. The predictor variables included in the regression analysis include child factors (age, gender, comorbidity, and medication use) and family factors (exposure to parental psychopathology, primary parent’s educational attainment, marital status). Age (calculated from the DISC-IV interview date and date of birth) was treated as a
One of the most influential sociological papers was put forth in 1978 by the po- litical scientist Ithiel de Sola Pool and the mathematician Manfred Kochen in their paper “Contacts and Influence” . The paper concerns social network structure and patterns. Written in 1958, it was not published until twenty years later because the authors were not satisfied with the depth of their work. A manuscript was produced though, and the paper was un-officially circulated amongst the relevant research com- munity. The paper put forth many of the crucial issues that came to define the field for some time after. In this network, they treat people as vertices and acquaintances between two people as an edge. Issues addressed involve an individual person’s de- gree, degree distributions, average and range of degrees, high-degree people, network structure, probability of a random acquaintance, probability of shared acquaintances or neighbors, and shortest path lengths. Due to the insufficiency of empirical data, they used the random graph model. They were also the first to scientifically intro- duce the notion of the small-world effect, popularized as “6 degrees of separation”, which refers to the idea that everybody in the world is within a relatively short social distance of everybody else , page 15.
microcarriers were dispensed into ring-shaped agarose molds and shown to adhere to form living tissue constructs after several days in culture. The ability of cellularized microcarriers to adhere to one another involved cellular and extracellular matrix bridging that included the formation of epithelium-like cell layers lining the luminal and ablumenal surfaces of the constructs and the deposition of collagen and elastin fibers. The ring-shaped tissues nominally behaved as elastic solids, with a uniaxial mechanical response that is qualitatively similar to that of native vascular tissues and consistent with their elastin and collagen composition. Linearized measures of the mechanical response of the fabricated tissues at both low and high strains were observed to increase with duration of static culture, with no significant loss of stiffness following decellularization. The findings highlight the utility of cellularized macroporous gelatin microcarriers as self-adhering building blocks for the fabrication of living ring-shaped structures.
The model is implemented in the circuit simulator PSpice and is validated by comparison with Atlas finite element simulations and experimental measurements. A highpower SiC DMOSFET from CREE Inc., rated at 1200V 20A, is used for experimental validation. The device inner construction details are not available from the manufacturer. On the basis of experimental parameter extraction and literature published by CREE [ 33 ], the geometrical and doping characteristics of Figure 3.1 have been derived. These characteristics are used both for the finite element simulation model and for the PSpice model. A full set of experimental measurements is performed in order to assist model validation, including: static I-V characteristics, C-V characteristics and dynamic characterization under resistive switching conditions.
Power electronic systems are accepted as the key technology to convert and control electrical power flow from one form to another efficiently. A scale of applications could range from a fraction of watt found in consumer products to a giga-watt scale found in utility applications. In some highpower applications, there may be case where a power switch used in the converter is in a form of multiple power semiconductor devices combined in series or parallel configuration in order to create a higher voltage or higher current switch respectively. For example, the 150-kV VSC-based HVDC transmission system presented in  utilises more than 20 IGBTs in one stack of the switches and connect up to 10 stacks in series to achieve the rated voltage. A high voltage Marx generator in  is another example where twelve IGBTs are connected in series to form a single switch with 10 kV and 300 A ratings. In some cases, using low-voltage semiconductor devices as a building block to achieve higher voltage switches is preferred over using a single high voltage device for the better switching performance like the scalable power semiconductor switch (SPSS) developed in .
investment, short construction period, simple equipment, communications security, real-time, no long distance relay and communication and a series of advantages. Power line carrier communication is one kind of communications that makes use of power line to transfer the data, voice, media and other signals. Power line carrier communication technology has the properties of high economic value, universality and practicability. With the rapid development of power electronics technology, switchingpower supply is widely used in power line communication equipment. Switchingpower supply becomes the key infrastructure of communications equipment and maintains a stable output voltage. Switchingpower supply controls the time ratio of the electronic switching device opened and shut off and electronic switching device modulates the pulse of the input voltage. Factors of switchingpower supply that affect the power line communication are Phase Noise, and Electromagnetic Interference. With the worldwide existing power grid infrastructure, power line communication (PLC) technology has received a renewed attention in the last decades. At the same time, applications based on this technology attract a lot Abstract: The idea of sending communication signals on the same pair of wires as are used for power distribution is as old as the telegraph itself, the number of communication devices installed on dedicated wiring far exceeds the number installed on AC mains wiring. Commercial spread spectrum power line communication has been the focus of research and product development at a number of companies since the early 1980’s. After nearly two decades of development, spread spectrum technology has still not delivered on its promise to provide the products required for the proliferation of power line communication. The idea of communication over power line has to be taken care of for the future prospects of communication. In the view of this we conceive the idea to communicate the information regarding the status of the power line to the sub-station. The development of the conceived idea needs full command and understanding of the technology and for this purpose a survey has been done in this paper showing the basic existing method for communication, its advantages and the drawbacks.
The highpower RF pulse is utilized in many applications including medical electronics, laser excitation and radars, etc. The most applicable application of RF highpower pulse signal is using in radar systems. But the research of high speed RF highpower pulse signal is not many compared to others [1–11]. Solid state power device is not higher output power and operating frequency, but wider bandwidth and higher reliability than vacuum tube . Recently, solid-state powerdevices which have the output power up to hundreds W at S- band have been developed . Moreover, we can obtain several kW output power by combining some devices. The pulsed power ampliﬁer can be realized by using a modulation or a switching method.
A bstract — In this context, the multilevel inverters with larger number of levels suitable for circuit integration are actively investigated. Diode- clamped multilevel inverters are regarded as the promising solution. As the number of voltage levels increases the harmonic content decreases significantly.The general function of the multilevel inverter is to synthesize a desired AC voltage from several levels of DC voltages. Multilevel inverters are mainly used in medium voltage and highpower applications to reduce the required voltage rating of the power semiconductor switchingdevices. These multilevel inverters are used to increase inverter operating voltage, to minimize THD with low switching frequency, to reduce EMI due to lower voltage steps. The advantages of this multilevel approach include good power quality, good electromagnetic compatibility, low switching losses and high capability. This project proposes to study various multilevel inverter topologies, to simulate various modulating techniques for diode clamped multi level inverter fed induction motor. These modulating techniques include sinusoidal pulse width modulation, modified reference modulating techniques. i.e., trapezoidal reference, staircase reference, stepped reference, third harmonic injected reference and offset line voltage injected reference with triangular carrier waves. The main objective of this study is to reduce total harmonic distortion, comparison of THD and fundamental component for different modulation techniques. The Simulated Induction motor model is connected at the end to observe the Stator current harmonics and speed-torque characteristics.
Children with high Surgency ratings are more likely to act out in impulsive or disruptive manners (Gartstein et al., 2012). Previous literature reviews have found that the Surgency facets of activity level and social approach predict higher levels of ADHD symptoms (Nigg et al., 2004, Nigg, 2006; Casalin, et al., 2011). These traits manifest in challenging behaviors associated with ADHD such as dampened abilities in anger control and non-compliance (De Pauw & Mervielde, 2011). Also, children with ADHD were rated one standard deviation higher on the Children’s Behavior Questionnaire (Rothbart et al., 2001) scale of activity level when compared to the average rating of the general population. Additionally, activity level relates to how intensely a child exhibits other traits such as impulsivity, shyness, and approach (De Pauw & Mervielde, 2011). Surgency’s relationship to activity level (indicating hyperactivity), the stability of impulsivity, and social approach indicates the potential and value of studying the relationship between early temperament characteristics and the emergence of ADHD. This relationship has not been thoroughly examined in FXS as a possible explanation for the elevated ratings of ADHD features observed in the literature (Bailey et al., 2001; Bailey et al., 2008; Sullivan et al., 2006).
However, ferritic alloys have also been observed to have a somewhat non-uniform nanoparticle dispersion, be difficult to manufacture, and susceptible to embrittlement at high temperatures due to an undesirable phase transformation between 400°C and 550°C , . 9Cr ODS is unique in that there is the observed formation of a non- equilibrium phase, designated as the residual ferrite, which serves to greatly enhance several vital mechanical properties in comparison to both standard RAFM alloys and the fully ferritic 18Cr ODS. This is theorized to be further enhanced by sliding at weaker regions such as at the grain boundaries and packet boundaries; behaving as a fiber composite material comprising the harder residual ferrite and the softer tempered martensite.  A martensitic alloy, such as 9Cr ODS, would be best utilized in areas exposed to high temperatures, neutron doses, and mechanical strain, such as fuel cladding within the reactor pressure vessel. 18Cr ODS would be more valuable for application as structural components that are in contact with coolant, as the high chromium content lends to good resistance to corrosion.
Demand for high-voltage, highpower converters capable of producing high-quality waveforms while utilizing low voltage devices and reduced switching frequencies has led to the multilevel inverter development with regard to semiconductor power switch voltage limits. Multilevel inverters include an array of power semiconductors and capacitor voltage sources, the output of which generate voltages with . stepped waveforms. The commutation of the switches permits the addition of the capacitor voltages, which reach high voltage at the output, while the power
While Diode-Clamped (DC-MLI) and Flying Capacitor (FC-MLI) are widely used for industrial medium voltage highpower applications when just low number of levels (typically three) is required, Cascaded H-Bridge inverters (CHB-MLI) are most suitable for high voltage-highpower, HVDC utility applications. Mainly due its modular structure which can be extended for high number of levels with no much complexity. Furthermore, with CHB-MLI, higher power and voltage capability can be achieved at lowest number of required devices compared to DC-MLI and FCMLI. The CHB-MLI uses series connection of single phase h-bridge inverters with separate dc sources. The main idea is that each bridge cell will generate three different voltages and the output waveform can be synthesized by the sum of the voltages generated by each cell. The separate dc sources might be solar panel PV cells or fuel cells.