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, legislation which defines the state's interconnection standards and permits the interconnection of smart the cost and benefits of advanced inverter enabling legislation. Expect conversations concerning

Complementary structure for designer localized surface plasmons

NASA Astrophysics Data System (ADS)

Gao, Zhen; Gao, Fei; Zhang, Youming; Zhang, Baile

2015-11-01

Magnetic localized surface plasmons (LSPs) supported on metallic structures corrugated by very long and curved grooves have been recently proposed and demonstrated on an extremely thin metallic spiral structure (MSS) in the microwave regime. However, the mode profile for the magnetic LSPs was demonstrated by measuring only the electric field, not the magnetic field. Here, based on Babinet's principle, we propose a Babinet-inverted, or complementary MSS whose electric/magnetic mode profiles match the magnetic/electric mode profiles of MSS. This complementarity of mode profiles allows mapping the magnetic field distribution of magnetic LSP mode profile on MSS by measuring the electric field distribution of the corresponding mode on complementary MSS. Experiment at microwave frequencies also demonstrate the use of complementary MSS in sensing refractive-index change in the environment.

Mid-Gap States and Normal vs Inverted Bonding in Luminescent Cu+- and Ag+-Doped CdSe Nanocrystals.

PubMed

Nelson, Heidi D; Hinterding, Stijn O M; Fainblat, Rachel; Creutz, Sidney E; Li, Xiaosong; Gamelin, Daniel R

2017-05-10

Mid-gap luminescence in copper (Cu + )-doped semiconductor nanocrystals (NCs) involves recombination of delocalized conduction-band electrons with copper-localized holes. Silver (Ag + )-doped semiconductor NCs show similar mid-gap luminescence at slightly (∼0.3 eV) higher energy, suggesting a similar luminescence mechanism, but this suggestion appears inconsistent with the large difference between Ag + and Cu + ionization energies (∼1.5 eV), which should make hole trapping by Ag + highly unfavorable. Here, Ag + -doped CdSe NCs (Ag + :CdSe) are studied using time-resolved variable-temperature photoluminescence (PL) spectroscopy, magnetic circularly polarized luminescence (MCPL) spectroscopy, and time-dependent density functional theory (TD-DFT) to address this apparent paradox. In addition to confirming that Ag + :CdSe and Cu + :CdSe NCs display similar broad PL with large Stokes shifts, we demonstrate that both also show very similar temperature-dependent PL lifetimes and magneto-luminescence. Electronic-structure calculations further predict that both dopants generate similar localized mid-gap states. Despite these strong similarities, we conclude that these materials possess significantly different electronic structures. Specifically, whereas photogenerated holes in Cu + :CdSe NCs localize primarily in Cu(3d) orbitals, formally oxidizing Cu + to Cu 2+ , in Ag + :CdSe NCs they localize primarily in 4p orbitals of the four neighboring Se 2- ligands, and Ag + is not oxidized. This difference reflects a shift from "normal" to "inverted" bonding going from Cu + to Ag + . The spectroscopic similarities are explained by the fact that, in both materials, photogenerated holes are localized primarily within covalent [MSe 4 ] dopant clusters (M = Ag + , Cu + ). These findings reconcile the similar spectroscopies of Ag + - and Cu + -doped semiconductor NCs with the vastly different ionization potentials of their Ag + and Cu + dopants.

Addressable inverter matrix for process and device characterization

NASA Technical Reports Server (NTRS)

Buehler, M. G.; Sayah, H. R.

1985-01-01

The addressable inverter matrix consists of 222 inverters each accessible with the aid of a shift register. The structure has proven useful in characterizing the variability of inverter transfer curves and in diagnosing processing faults. For good 3-micron CMOS bulk inverters investigated, the percent standard deviation of the inverter threshold voltage was less than one percent and the inverter gain (the slope of the inverter transfer curve at the inverter threshold vltage) was less than 3 percent. The average noise margin for the inverters was near 2 volts for a power supply voltage of 5 volts. The specific faults studied included undersize pull-down transistor widths and various open contacts in the matrix.

Addressable inverter matrix for process and device characterization

NASA Technical Reports Server (NTRS)

Buehler, M. G.; Sayah, H. R.

1985-01-01

The addressable inverter matrix consists of 222 inverters each accessible with the aid of a shift register. The structure has proven useful in characterizing the variability of inverter transfer curves and in diagnosing processing faults. For good 3-micron CMOS bulk inverters investigated in this study, the percent standard deviation of the inverter threshold voltage was less than one percent and the inverter gain (the slope of the inverter transfer curve at the inverter threshold voltage) was less than 3 percent. The average noise margin for the inverters was near 2 volts for a power supply voltage of 5 volts. The specific faults studied included undersize pull-down transistor widths and various open contacts in the matrix.

Parameters Design of Series Resonant Inverter Circuit

NASA Astrophysics Data System (ADS)

Qi, Xingkun; Peng, Yonglong; Li, Yabin

This paper analyzes the main circuit structure of series resonant inverter, and designs the components parameters of the main circuit.That provides a theoretical method for the design of series resonant inverter.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doug Blankenship

PDFs of seismic reflection profiles 101,110, 111 local to the West Flank FORGE site. 45 line kilometers of seismic reflection data are processed data collected in 2001 through the use of vibroseis trucks. The initial analysis and interpretation of these data was performed by Unruh et al. (2001). Optim processed these data by inverting the P-wave first arrivals to create a 2-D velocity structure. Kirchhoff images were then created for each line using velocity tomograms (Unruh et al., 2001).

Multi-Lagrangians for integrable systems

NASA Astrophysics Data System (ADS)

Nutku, Y.; Pavlov, M. V.

2002-03-01

We propose a general scheme to construct multiple Lagrangians for completely integrable nonlinear evolution equations that admit multi-Hamiltonian structure. The recursion operator plays a fundamental role in this construction. We use a conserved quantity higher/lower than the Hamiltonian in the potential part of the new Lagrangian and determine the corresponding kinetic terms by generating the appropriate momentum map. This leads to some remarkable new developments. We show that nonlinear evolutionary systems that admit N-fold first order local Hamiltonian structure can be cast into variational form with 2N-1 Lagrangians which will be local functionals of Clebsch potentials. This number increases to 3N-2 when the Miura transformation is invertible. Furthermore we construct a new Lagrangian for polytropic gas dynamics in 1+1 dimensions which is a free, local functional of the physical field variables, namely density and velocity, thus dispensing with the necessity of introducing Clebsch potentials entirely. This is a consequence of bi-Hamiltonian structure with a compatible pair of first and third order Hamiltonian operators derived from Sheftel's recursion operator.

Index Compression and Efficient Query Processing in Large Web Search Engines

ERIC Educational Resources Information Center

Ding, Shuai

2013-01-01

The inverted index is the main data structure used by all the major search engines. Search engines build an inverted index on their collection to speed up query processing. As the size of the web grows, the length of the inverted list structures, which can easily grow to hundreds of MBs or even GBs for common terms (roughly linear in the size of…

Number word structure in first and second language influences arithmetic skills

PubMed Central

Prior, Anat; Katz, Michal; Mahajna, Islam; Rubinsten, Orly

2015-01-01

Languages differ in how they represent numerical information, and specifically whether the verbal notation of numbers follows the same order as the symbolic notation (in non-inverted languages, e.g., Hebrew, “25, twenty-five”) or whether the two notations diverge (in inverted languages, e.g., Arabic, “25, five-and-twenty”). We examined how the structure of number–words affects how arithmetic operations are processed by bilingual speakers of an inverted and a non-inverted language. We examined Arabic–Hebrew bilinguals’ performance in the first language, L1 (inverted) and in the second language, L2 (non-inverted). Their performance was compared to that of Hebrew L1 speakers, who do not speak an inverted language. Participants judged the accuracy of addition problems presented aurally in L1, aurally in L2 or in visual symbolic notation. Problems were presented such that they matched or did not match the structure of number words in the language. Arabic–Hebrew bilinguals demonstrated both flexibility in processing and adaptation to the language of aural–verbal presentation – they were more accurate for the inverted order of presentation in Arabic, but more accurate for non-inverted order of presentation in Hebrew, thus exhibiting the same pattern found for native Hebrew speakers. In addition, whereas native Hebrew speakers preferred the non-inverted order in visual symbolic presentation as well, the Arabic–Hebrew bilinguals showed enhanced flexibility, without a significant preference for one order over the other, in either speed or accuracy. These findings suggest that arithmetic processing is sensitive to the linguistic representations of number words. Moreover, bilinguals exposed to inverted and non-inverted languages showed influence of both systems, and enhanced flexibility in processing. Thus, the L1 does not seem to have exclusive power in shaping numerical mental representations, but rather the system remains open to influences from a later learned L2. PMID:25852591

3-D inversion of airborne electromagnetic data parallelized and accelerated by local mesh and adaptive soundings

NASA Astrophysics Data System (ADS)

Yang, Dikun; Oldenburg, Douglas W.; Haber, Eldad

2014-03-01

Airborne electromagnetic (AEM) methods are highly efficient tools for assessing the Earth's conductivity structures in a large area at low cost. However, the configuration of AEM measurements, which typically have widely distributed transmitter-receiver pairs, makes the rigorous modelling and interpretation extremely time-consuming in 3-D. Excessive overcomputing can occur when working on a large mesh covering the entire survey area and inverting all soundings in the data set. We propose two improvements. The first is to use a locally optimized mesh for each AEM sounding for the forward modelling and calculation of sensitivity. This dedicated local mesh is small with fine cells near the sounding location and coarse cells far away in accordance with EM diffusion and the geometric decay of the signals. Once the forward problem is solved on the local meshes, the sensitivity for the inversion on the global mesh is available through quick interpolation. Using local meshes for AEM forward modelling avoids unnecessary computing on fine cells on a global mesh that are far away from the sounding location. Since local meshes are highly independent, the forward modelling can be efficiently parallelized over an array of processors. The second improvement is random and dynamic down-sampling of the soundings. Each inversion iteration only uses a random subset of the soundings, and the subset is reselected for every iteration. The number of soundings in the random subset, determined by an adaptive algorithm, is tied to the degree of model regularization. This minimizes the overcomputing caused by working with redundant soundings. Our methods are compared against conventional methods and tested with a synthetic example. We also invert a field data set that was previously considered to be too large to be practically inverted in 3-D. These examples show that our methodology can dramatically reduce the processing time of 3-D inversion to a practical level without losing resolution. Any existing modelling technique can be included into our framework of mesh decoupling and adaptive sampling to accelerate large-scale 3-D EM inversions.

8. Inverted siphon structure carrying ditch flow under Willow Creek, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. Inverted siphon structure carrying ditch flow under Willow Creek, looking southwest - Natomas Ditch System, Blue Ravine Segment, Juncture of Blue Ravine & Green Valley Roads, Folsom, Sacramento County, CA

7. Inverted siphon structure carrying ditch flow under Willow Creek, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. Inverted siphon structure carrying ditch flow under Willow Creek, looking east - Natomas Ditch System, Blue Ravine Segment, Juncture of Blue Ravine & Green Valley Roads, Folsom, Sacramento County, CA

Face inversion effects in autism: a combined looking time and pupillometric study.

PubMed

Falck-Ytter, Terje

2008-10-01

Previous research has found that in typically developing individuals, behavioral performance declines and electrophysiological brain responses are altered when the face is inverted. Such effects are generally attributed to disruption of configural information. Individuals with autism spectrum disorder (ASD) have been found to show less pronounced inversion effects, a result in line with the view that featural processing of faces is enhanced in ASD. No study has determined if, or how, such local bias is reflected in the eye movements used in face observation. In this eye tracking study, looking time and pupil dilation were investigated during the presentation of upright and inverted faces in preschool children with ASD and typically developing preschoolers. On average, both children with ASD and typically developing children looked less at the face and the eye areas during inverted presentations than during upright presentations. Nevertheless, individuals with ASD had a stronger tendency than typically developing children to look at the same face features during upright and inverted presentations, which is suggestive of a local bias. Pupil dilation, reflecting increased processing load, was larger for inverted than upright faces in the ASD group only, and pupillary inversion effects were stronger in ASD than in typically developing children.

The use of the multiwavelet transform for the estimation of surface wave group and phase velocities and their associated uncertainties

NASA Astrophysics Data System (ADS)

Poppeliers, C.; Preston, L. A.

2017-12-01

Measurements of seismic surface wave dispersion can be used to infer the structure of the Earth's subsurface. Typically, to identify group- and phase-velocity, a series of narrow-band filters are applied to surface wave seismograms. Frequency dependent arrival times of surface waves can then be identified from the resulting suite of narrow band seismograms. The frequency-dependent velocity estimates are then inverted for subsurface velocity structure. However, this technique has no method to estimate the uncertainty of the measured surface wave velocities, and subsequently there is no estimate of uncertainty on, for example, tomographic results. For the work here, we explore using the multiwavelet transform (MWT) as an alternate method to estimate surface wave speeds. The MWT decomposes a signal similarly to the conventional filter bank technique, but with two primary advantages: 1) the time-frequency localization is optimized in regard to the time-frequency tradeoff, and 2) we can use the MWT to estimate the uncertainty of the resulting surface wave group- and phase-velocities. The uncertainties of the surface wave speed measurements can then be propagated into tomographic inversions to provide uncertainties of resolved Earth structure. As proof-of-concept, we apply our technique to four seismic ambient noise correlograms that were collected from the University of Nevada Reno seismic network near the Nevada National Security Site. We invert the estimated group- and phase-velocities, as well the uncertainties, for 1-D Earth structure for each station pair. These preliminary results generally agree with 1-D velocities that are obtained from inverting dispersion curves estimated from a conventional Gaussian filter bank.

Efficient cascade multiple heterojunction organic solar cells with inverted structure

NASA Astrophysics Data System (ADS)

Guo, Tingting; Li, Mingtao; Qiao, Zhenfang; Yu, Leiming; Zhao, Jianhong; Feng, Nianjun; Shi, Peiguang; Wang, Xiaoyan; Pu, Xiaoyun; Wang, Hai

2018-05-01

In this work, we demonstrate an efficient cascade multiple heterojunction organic solar cell with inverted structure. By using two donor materials, poly(3-hexylthiosphene) (P3HT) and titanyl phthalocyanine (TiOPc), as well as two acceptor materials, [6,6]-phenyl C61 butyric acid methyl ester (PCBM) and C60, the cascade multiple heterojunctions of P3HT:PCBM/TiOPc:C60/C60 have been constructed. Applying the optimized inverted configuration of FTO/Zinc Tin Oxide (ZTO)/C60 (30 nm)/TiOPc:C60 (1:1.5, 25 nm)/P3HT:PCBM (1:0.8, 100 nm)/MoO3 (4 nm)/Ag, the considerably enhanced open circuit voltage (VOC) and short circuit current (JSC) can be harvested together, and the power conversion efficiency (PCE) is three times higher than that of the control cell with conventional structure. The significant improvements of the inverted cell are mostly due to the broadened spectral absorption and high efficient multi-interface exciton dissociation in the cascade multiple heterojunctions, indicating that the optimized cascade heterojunctions match the inverted structure well.

Analysis and modeling of a family of two-transistor parallel inverters

NASA Technical Reports Server (NTRS)

Lee, F. C. Y.; Wilson, T. G.

1973-01-01

A family of five static dc-to-square-wave inverters, each employing a square-loop magnetic core in conjunction with two switching transistors, is analyzed using piecewise-linear models for the nonlinear characteristics of the transistors, diodes, and saturable-core devices. Four of the inverters are analyzed in detail for the first time. These analyses show that, by proper choice of a frame of reference, each of the five quite differently appearing inverter circuits can be described by a common equivalent circuit. This equivalent circuit consists of a five-segment nonlinear resistor, a nonlinear saturable reactor, and a linear capacitor. Thus, by proper interpretation and identification of the parameters in the different circuits, the results of a detailed solution for one of the inverter circuits provide similar information and insight into the local and global behavior of each inverter in the family.

Inverts permittivity and conductivity with structural constraint in GPR FWI based on truncated Newton method

NASA Astrophysics Data System (ADS)

Ren, Qianci

2018-04-01

Full waveform inversion (FWI) of ground penetrating radar (GPR) is a promising technique to quantitatively evaluate the permittivity and conductivity of near subsurface. However, these two parameters are simultaneously inverted in the GPR FWI, increasing the difficulty to obtain accurate inversion results for both parameters. In this study, I present a structural constrained GPR FWI procedure to jointly invert the two parameters, aiming to force a structural relationship between permittivity and conductivity in the process of model reconstruction. The structural constraint is enforced by a cross-gradient function. In this procedure, the permittivity and conductivity models are inverted alternately at each iteration and updated with hierarchical frequency components in the frequency domain. The joint inverse problem is solved by the truncated Newton method which considering the effect of Hessian operator and using the approximated solution of Newton equation to be the perturbation model in the updating process. The joint inversion procedure is tested by three synthetic examples. The results show that jointly inverting permittivity and conductivity in GPR FWI effectively increases the structural similarities between the two parameters, corrects the structures of parameter models, and significantly improves the accuracy of conductivity model, resulting in a better inversion result than the individual inversion.

A Single Phase 7-Level Cascade Inverter Topology with Reduced Number of Switches on Resistive Load by Using PWM

NASA Astrophysics Data System (ADS)

Hamzah, H. H.; Ponniran, A.; Kasiran, A. N.; Harimon, M. A.; Gendum, D. A.; Yatim, M. H.

2018-04-01

This paper discussing design principles of inverter structure with reduced number of semiconductor devices of seven levels symmetric H-bridge multilevel inverter (MLI) topology. The aim of this paper is to design an inverter circuit with reduction of semiconductor losses, converter size and development cost. The H-bridge and auxiliary structures were considered in order to achieve seven levels output voltage. The performance of design circuit is compared with conventional seven levels structure in terms of voltage output. The circuit development consists of seven switches and three diode. A basic modulation technique is used to confirm the designed circuit. The results show that the designed circuit is able to convert seven level output voltage with low total harmonics distortion (THD) in voltage fundamental output. According to the results, fundamental output voltage is increased up to 8.314%, and the THD is decreased up to 0.81% compared to the conventional seven level inverter.

Study of liquid crystal space groups using controlled tilting with cryogenic transmission electron microscopy.

PubMed

Sagalowicz, Laurent; Acquistapace, Simone; Watzke, Heribert J; Michel, Martin

2007-11-20

We developed a method that enables differentiation between liquid crystalline-phase particles corresponding to different space groups. It consists of controlled tilting of the specimen to observe different orientations of the same particle using cryogenic transmission electron microscopy. This leads to the visualization of lattice planes (or reflections) that are present for a given structure and absent for the other one(s) and that give information on liquid crystalline structures and their space groups. In particular, we show that we can unambiguously distinguish among particles having the inverted micellar cubic (space group Fd(3)m, 227), the inverted bicontinuous gyroid (space group Ia(3)d, 230), the inverted bicontinuous diamond (space group Pn(3)m, 224), and the inverted bicontinuous primitive cubic structure (space group Im(3)m, 229).

Linear polarization-discriminatory state inverter fabricated by oblique angle deposition.

PubMed

Park, Yong Jun; Sobahan, K M A; Kim, Jin Joo; Hwangbo, Chang Kwon

2009-06-22

In this paper, we report a linear polarization-discriminatory state inverter made of three-layer sculpture thin film fabricated by oblique angle deposition technique. The first and third layers are quarter-wave plates of zigzag structure and the middle of them is a circular Bragg reflector of left-handed helical structure. It is found that the normal incidence of P-polarized light on this polarization-discriminatory state inverter becomes the S-polarized light at output, while the incident S-polarized light of wavelength lying in the Bragg regime is reflected. The microstructure of the linear polarization-discriminatory state inverter is also investigated by using a scanning electron microscope.

Difference in anisotropic etching characteristics of alkaline and copper based acid solutions for single-crystalline Si.

PubMed

Chen, Wei; Liu, Yaoping; Yang, Lixia; Wu, Juntao; Chen, Quansheng; Zhao, Yan; Wang, Yan; Du, Xiaolong

2018-02-21

The so called inverted pyramid arrays, outperforming conventional upright pyramid textures, have been successfully achieved by one-step Cu assisted chemical etching (CACE) for light reflection minimization in silicon solar cells. Due to the lower reduction potential of Cu 2+ /Cu and different electronic properties of different Si planes, the etching of Si substrate shows orientation-dependent. Different from the upright pyramid obtained by alkaline solutions, the formation of inverted pyramid results from the coexistence of anisotropic etching and localized etching process. The obtained structure is bounded by Si {111} planes which have the lowest etching rate, no matter what orientation of Si substrate is. The Si etching rate and (100)/(111) etching ratio are quantitatively analyzed. The different behaviors of anisotropic etching of Si by alkaline and Cu based acid etchant have been systematically investigated.

Efficient atom localization via probe absorption in an inverted-Y atomic system

NASA Astrophysics Data System (ADS)

Wu, Jianchun; Wu, Bo; Mao, Jiejian

2018-06-01

The behaviour of atom localization in an inverted-Y atomic system is theoretically investigated. For the atoms interacting with a weak probe field and several orthogonal standing-wave fields, their position information can be obtained by measuring the probe absorption. Compared with the traditional scheme, we couple the probe field to the transition between the middle and top levels. It is found that the probe absorption sensitively depends on the detuning and strength of the relevant light fields. Remarkably, the atom can be localized at a particular position in the standing-wave fields by coupling a microwave field to the transition between the two ground levels.

Boundary layer polarization and voltage in the 14 MLT region

NASA Astrophysics Data System (ADS)

Lundin, R.; Yamauchi, M.; Woch, J.; Marklund, G.

1995-05-01

Viking midlatitude observations of ions and electrons in the postnoon auroral region show that field-aligned acceleration of electrons and ions with energies up to a few kiloelectron volts takes place. The characteristics of the upgoing ion beams and the local transverse electric field observed by Viking indicate that parallel ion acceleration is primarily due to a quasi-electrostatic field-aligned acceleration process below Viking altitudes, i.e., below 10,000-13,500 km. A good correlation is found between the maximum upgoing ion beam energy and the depth of the local potential well determined by the Viking electric field experiment within dayside 'ion inverted Vs.' The total transverse potential throughout the entire region near the ion inverted Vs. is generally much higher than the field-aligned potential and may reach well above 10 kV. However, the detailed mapping of the transverse potential out to the boundary layer, a fundamental issue which remains controversial, was not attempted here. An important finding in this study is the strong correlation between the maximum up going ion beam energy of dayside ion inverted Vs and the solar wind velocity. This suggests a direct coupling of the solar wind plasma dynamo/voltage generator to the region of field-aligned particle acceleration. The fact that the center of dayside ion inverted Vs coincide with convection reversals/flow stagnation and upward Birkeland currents on what appears to be closed field lines (Woch et al., 1993), suggests that field-aligned potential structures connect to the inner part of an MHD dyanmo in the low-latitude boundary layer. Thus the Viking observations substantiate the idea of a solar wind induced boundary layer polarization where negatively charged perturbations in the postnoon sector persistently develops along the magnetic field lines, establishing accelerating potential drops along the geomagnetic field lines in the 0.5-10 kV range.

Topology of the germ plasm and development of primordial germ cells in inverted amphibian eggs

NASA Technical Reports Server (NTRS)

Wakahara, M.; Neff, A. W.; Malacinski, G. M.

1984-01-01

Inverted Xenopus eggs have reduced numbers of primordial germ cells (PGCs). The extent of the reduction varies from spawning to spawning. Histologic examination revealed that PGC counts were lowest in inverted eggs which displayed the greatest amount of shift in the vegetal mass of large yolk platelets, although the germ plasm itself always remained localized in the egg's original vegetal hemisphere. Even at blastulation the germ plasm continued to be localized in the egg's original vegetal hemisphere. In many cases, however, it was confined to the periphery of the embryo, which probably accounts for the reduced PGC number in some tadpoles. In other cases it may have been dispersed and therefore not detectable in histologic analyses. Although the altered site of involution in inverted embryos did not influence PGC development, subsequent cell movement patterns apparently did. Those embryos which displayed the largest degree of pattern reversal at the tail-bud stage also exhibited the most extreme reduction in PGC numbers. A brief cold shock (4 degrees C, 10 min) prior to first cleavage leads to a further reduction in PGC numbers in inverted embryos, probably as a result of the displacement of the germ plasm away from its original vegetal pole location.

Stochastic Inversion of Geomagnetic Observatory Data Including Rigorous Treatment of the Ocean Induction Effect With Implications for Transition Zone Water Content and Thermal Structure

NASA Astrophysics Data System (ADS)

Munch, F. D.; Grayver, A. V.; Kuvshinov, A.; Khan, A.

2018-01-01

In this paper we estimate and invert local electromagnetic (EM) sounding data for 1-D conductivity profiles in the presence of nonuniform oceans and continents to most rigorously account for the ocean induction effect that is known to strongly influence coastal observatories. We consider a new set of high-quality time series of geomagnetic observatory data, including hitherto unused data from island observatories installed over the last decade. The EM sounding data are inverted in the period range 3-85 days using stochastic optimization and model exploration techniques to provide estimates of model range and uncertainty. The inverted conductivity profiles are best constrained in the depth range 400-1,400 km and reveal significant lateral variations between 400 km and 1,000 km depth. To interpret the inverted conductivity anomalies in terms of water content and temperature, we combine laboratory-measured electrical conductivity of mantle minerals with phase equilibrium computations. Based on this procedure, relatively low temperatures (1200-1350°C) are observed in the transition zone (TZ) underneath stations located in Southern Australia, Southern Europe, Northern Africa, and North America. In contrast, higher temperatures (1400-1500°C) are inferred beneath observatories on islands, Northeast Asia, and central Australia. TZ water content beneath European and African stations is ˜0.05-0.1 wt %, whereas higher water contents (˜0.5-1 wt %) are inferred underneath North America, Asia, and Southern Australia. Comparison of the inverted water contents with laboratory-constrained water storage capacities suggests the presence of melt in or around the TZ underneath four geomagnetic observatories in North America and Northeast Asia.

Acoustic Impedance Inversion of Seismic Data Using Genetic Algorithm

NASA Astrophysics Data System (ADS)

Eladj, Said; Djarfour, Noureddine; Ferahtia, Djalal; Ouadfeul, Sid-Ali

2013-04-01

The inversion of seismic data can be used to constrain estimates of the Earth's acoustic impedance structure. This kind of problem is usually known to be non-linear, high-dimensional, with a complex search space which may be riddled with many local minima, and results in irregular objective functions. We investigate here the performance and the application of a genetic algorithm, in the inversion of seismic data. The proposed algorithm has the advantage of being easily implemented without getting stuck in local minima. The effects of population size, Elitism strategy, uniform cross-over and lower mutation are examined. The optimum solution parameters and performance were decided as a function of the testing error convergence with respect to the generation number. To calculate the fitness function, we used L2 norm of the sample-to-sample difference between the reference and the inverted trace. The cross-over probability is of 0.9-0.95 and mutation has been tested at 0.01 probability. The application of such a genetic algorithm to synthetic data shows that the inverted acoustic impedance section was efficient. Keywords: Seismic, Inversion, acoustic impedance, genetic algorithm, fitness functions, cross-over, mutation.

A new type of single-phase five-level inverter

NASA Astrophysics Data System (ADS)

Xu, Zhi; Li, Shengnan; Qin, Risheng; Zhao, Yanhang

2017-11-01

At present, Neutral Point Clamped (NPC) multilevel inverter is widely applied in new energy field. However, it has some disadvantages including low utilization rate of direct current (DC) voltage source and the unbalance of neutral potential. Therefore, a new single-phase five level inverter is proposed in this paper. It has two stage structure, the former stage is equivalent to three level DC/DC converter, and the back stage uses H bridge to realize inverter. Compared with the original central clamp type inverter, the new five level inverter can improve the utilization of DC voltage, and realize the neutral point potential balance with hysteresis comparator.

Experimental Evaluation of Load Rejection Over-Voltage from Grid-Tied Solar Inverters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Austin; Hoke, Andy, Chakraborty, Sudipta; Ropp, Michael

This paper investigates the impact of load rejection over-voltage (LRO) from commercially available grid-tied photovoltaic (PV) solar inverters. LRO can occur when a local feeder or breaker opens and the power output from a distributed energy resource exceeds the load power. Simplified models of current controlled inverters can over-predict over-voltage magnitudes, thus it is useful to quantify testing. The load rejection event was replicated using a hardware testbed at the National Renewable Energy Laboratory (NREL), and a set of commercially available PV inverters was tested to quantify the impact of LRO for a range of generation-to-load ratios. The magnitude andmore » duration of the over-voltage events are reported in this paper along with a discussion of characteristic inverter output behavior. The results for the inverters under test showed that maximum over-voltage magnitudes were less than 200 percent of nominal voltage, and much lower in many test cases. These research results are important because utilities that interconnect inverter-based DER need to understand their characteristics under abnormal grid conditions.« less

Local-time survey of plasma at low altitudes over the auroral zones.

NASA Technical Reports Server (NTRS)

Frank, L. A.; Ackerson, K. L.

1972-01-01

Local-time survey of the low-energy proton and electron intensities precipitated into the earth's atmosphere over the auroral zones during periods of magnetic quiescence. This survey was constructed by selecting a typical individual satellite crossing of this region in each of eight local-time sectors from a large library of similar observations with the polar-orbiting satellite Injun 5. The trapping boundary for more-energetic electron intensities, E greater than 45 keV, was found to be a 'natural coordinate' for delineating the boundary between the two major types of lower-energy, 50 less than or equal to E less than or equal to 15,000 eV, electron precipitation commonly observed over the auroral zones at low altitudes. Poleward of this trapping boundary inverted 'V' electron precipitation bands are observed in all local-time sectors. These inverted 'V' electron bands in the evening and midnight sectors are typically more energetic and have greater latitudinal widths than their counterparts in the noon and morning sectors. In general, the main contributors to the electron energy influx into the earth's atmosphere over the auroral zones are the electron inverted 'V' precipitation poleward of the trapping boundary in late evening, the plasma-sheet electron intensities equatorward of this boundary in early morning, and both of these precipitation events near local midnight.

Inverted Signature Trees and Text Searching on CD-ROMs.

ERIC Educational Resources Information Center

Cooper, Lorraine K. D.; Tharp, Alan L.

1989-01-01

Explores the new storage technology of optical data disks and introduces a data structure, the inverted signature tree, for storing data on optical data disks for efficient text searching. The inverted signature tree approach is compared to the use of text signatures and the B+ tree. (22 references) (Author/CLB)

2.3-MW Medium-Voltage, Three-Level Wind Energy Inverter Applying a Unique Bus Structure and 4.5-kV Si/SiC Hybrid Isolated Power Modules: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erdman, W.; Keller, J.; Grider, D.

A high-efficiency, 2.3-MW, medium-voltage, three-level inverter utilizing 4.5-kV Si/SiC (silicon carbide) hybrid modules for wind energy applications is discussed. The inverter addresses recent trends in siting the inverter within the base of multimegawatt turbine towers. A simplified split, three-layer laminated bus structure that maintains low parasitic inductances is introduced along with a low-voltage, high-current test method for determining these inductances. Feed-thru bushings, edge fill methods, and other design features of the laminated bus structure provide voltage isolation that is consistent with the 10.4-kV module isolation levels. Inverter efficiency improvement is a result of the (essential) elimination of the reverse recoverymore » charge present in 4.5-kV Si PIN diodes, which can produce a significant reduction in diode turn-off losses as well as insulated-gate bipolar transistor (IGBT) turn-on losses. The hybrid modules are supplied in industry-standard 140 mm x 130 mm and 190 mm x 130 mm packages to demonstrate direct module substitution into existing inverter designs. A focus on laminated bus/capacitor-bank/module subassembly level switching performance is presented.« less

Amplified DNAs in laboratory stocks of Leishmania tarentolae: extrachromosomal circles structurally and functionally similar to the inverted-H-region amplification of methotrexate-resistant Leishmania major

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrillo-Peixoto, M.L.; Beverley, S.M.

1988-12-01

We describe the structure of amplified DNA that was discovered in two laboratory stocks of the protozoan parasite Leishmania tarentolae. Restriction mapping and molecular cloning revealed that a region of 42 kilobases was amplified 8- to 30-fold in these lines. Southern blot analyses of digested DNAs or chromosomes separated by pulsed-field electrophoresis showed that the amplified DNA corresponded to the H region, a locus defined originally by its amplification in methotrexate-resistant Leishmania major. Similarities between the amplified DNA of the two species included (i) extensive cross-hybridization; (ii) approximate conservation of sequence order; (iii) extrachromosomal localization; (iv) an overall inverted, head-to-headmore » configuration as a circular 140-kilobase tetrameric molecule; (v) two regions of DNA sequence rearrangement, each of which was closely associated with the two centers of the inverted repeats; (vi) association with methotrexate resistance; and (vii) phenotypically conservative amplification, in which the wild-type chromosomal arrangement was retained without apparent modification. Our data showed that amplified DNA mediating drug resistance arose in unselected L. tarentolae, although the pressures leading to apparently spontaneous amplification and maintenance of the H region are not known. The simple structure and limited extent of DNA amplified in these and other Leishmania lines suggests that the study of gene amplification in Leishmania spp. offers an attractive model system for the study of amplification in cultured mammalian cells and tumors. We also introduced a method for measuring the size of large circular DNAs, using gamma-irradiation to introduce limited double-strand breaks followed by sizing of the linear DNAs by pulsed-field electrophoresis.« less

2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements.

PubMed

Lin, L; Ding, W X; Brower, D L

2014-11-01

Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.

2D image of local density and magnetic fluctuations from line-integrated interferometry-polarimetry measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, L., E-mail: lianglin@ucla.edu; Ding, W. X.; Brower, D. L.

2014-11-15

Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particlemore » transport flux and its spatial distribution are resolved.« less

Enhancement of thermoelectric characteristics in AlGaN/GaN films deposited on inverted pyramidal Si surfaces

NASA Astrophysics Data System (ADS)

Yalamarthy, Ananth Saran; So, Hongyun; Senesky, Debbie G.

2017-07-01

In this letter, we demonstrate an engineering strategy to boost thermoelectric power factor via geometry-induced properties of the pyramid structure. Aluminum gallium nitride (AlGaN)/GaN heterostructured films grown on inverted pyramidal silicon (Si) demonstrate higher power factor as compared to those grown on conventional flat Si substrates. We found that the magnitude of the Seebeck coefficient at room temperature increased from approximately 297 μVK-1 for the flat film to approximately 849 μVK-1 for the film on inverted pyramidal Si. In addition, the "effective" electrical conductivity of the AlGaN/GaN on the inverted pyramidal structure increased compared to the flat structure, generating an enhancement of thermoelectric power factor. The results demonstrate how manipulation of geometry can be used to achieve better thermoelectric characteristics in a manner that could be scaled to a variety of different material platforms.

Addressable Inverter Matrix Tests Integrated-Circuit Wafer

NASA Technical Reports Server (NTRS)

Buehler, Martin G.

1988-01-01

Addressing elements indirectly through shift register reduces number of test probes. With aid of new technique, complex test structure on silicon wafer tested with relatively small number of test probes. Conserves silicon area by reduction of area devoted to pads. Allows thorough evaluation of test structure characteristics and of manufacturing process parameters. Test structure consists of shift register and matrix of inverter/transmission-gate cells connected to two-by-ten array of probe pads. Entire pattern contained in square area having only 1.6-millimeter sides. Shift register is conventional static CMOS device using inverters and transmission gates in master/slave D flip-flop configuration.

Dynamically Babinet-invertible metasurface: a capacitive-inductive reconfigurable filter for terahertz waves using vanadium-dioxide metal-insulator transition

NASA Astrophysics Data System (ADS)

Urade, Yoshiro; Nakata, Yosuke; Okimura, Kunio; Nakanishi, Toshihiro; Miyamaru, Fumiaki; Takeda, Mitsuo W.; Kitano, Masao

2016-03-01

This paper proposes a reconfigurable planar metamaterial that can be switched between capacitive and inductive responses using local changes in the electrical conductivity of its constituent material. The proposed device is based on Babinet's principle and exploits the singular electromagnetic responses of metallic checkerboard structures, which are dependent on the local electrical conductivity. Utilizing the heating-induced metal-insulator transition of vanadium dioxide ($\\mathrm{VO}_2$), the proposed metamaterial is designed to compensate for the effect of the substrate and is experimentally characterized in the terahertz regime. This reconfigurable metamaterial can be utilized as a switchable filter and as a switchable phase shifter for terahertz waves.

Dynamically Babinet-invertible metasurface: a capacitive-inductive reconfigurable filter for terahertz waves using vanadium-dioxide metal-insulator transition.

PubMed

Urade, Yoshiro; Nakata, Yosuke; Okimura, Kunio; Nakanishi, Toshihiro; Miyamaru, Fumiaki; Takeda, Mitsuo W; Kitano, Masao

2016-03-07

This paper proposes a reconfigurable planar metamaterial that can be switched between capacitive and inductive responses using local changes in the electrical conductivity of its constituent material. The proposed device is based on Babinet's principle and exploits the singular electromagnetic responses of metallic checkerboard structures, which are dependent on the local electrical conductivity. Utilizing the heating-induced metal-insulator transition of vanadium dioxide (VO 2 ), the proposed meta-material is designed to compensate for the effect of the substrate and is experimentally characterized in the terahertz regime. This reconfigurable metamaterial can be utilized as a switchable filter and as a switchable phase shifter for terahertz waves.

Development of Low-Cost Inverted Microscope to Detect Early Growth of Mycobacterium tuberculosis in MODS Culture

PubMed Central

Zimic, Mirko; Velazco, Abner; Comina, Germán; Coronel, Jorge; Fuentes, Patricia; Luna, Carmen G.; Sheen, Patricia; Gilman, Robert H.; Moore, David A. J.

2010-01-01

Background The microscopic observation drug susceptibility (MODS) assay for rapid, low-cost detection of tuberculosis and multidrug resistant tuberculosis depends upon visualization of the characteristic cording colonies of Mycobacterium tuberculosis in liquid media. This has conventionally required an inverted light microscope in order to inspect the MODS culture plates from below. Few tuberculosis laboratories have this item and the capital cost of $5,000 for a high-end microscope could be a significant obstacle to MODS roll-out. Methodology We hypothesized that the precise definition provided by costly high-specification inverted light microscopes might not be necessary for pattern recognition. Significance In this work we describe the development of a low-cost artesenal inverted microscope that can operate in both a standard or digital mode to effectively replace the expensive commercial inverted light microscope, and an integrated system that could permit a local and remote diagnosis of tuberculosis. PMID:20351778

Design of an Internal Model Control strategy for single-phase grid-connected PWM inverters and its performance analysis with a non-linear local load and weak grid.

PubMed

Chaves, Eric N; Coelho, Ernane A A; Carvalho, Henrique T M; Freitas, Luiz C G; Júnior, João B V; Freitas, Luiz C

2016-09-01

This paper presents the design of a controller based on Internal Model Control (IMC) applied to a grid-connected single-phase PWM inverter. The mathematical modeling of the inverter and the LCL output filter, used to project the 1-DOF IMC controller, is presented and the decoupling of grid voltage by a Feedforward strategy is analyzed. A Proportional - Resonant Controller (P+Res) was used for the control of the same plant in the running of experimental results, thus moving towards the discussion of differences regarding IMC and P+Res performances, which arrived at the evaluation of the proposed control strategy. The results are presented for typical conditions, for weak-grid and for non-linear local load, in order to verify the behavior of the controller against such situations. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Ru(II)-based metallosurfactant forming inverted aggregates.

PubMed

Domínguez-Gutiérrez, David; Surtchev, Marko; Eiser, Erika; Elsevier, Cornelis J

2006-02-01

Knowing the advantages of incorporating a transition metal into interfaces, we report on the first inverted aggregates formed using metallosurfactants. The metallosurfactant possesses four long linear tails that account for the shielding of the polar headgroup in apolar solvents. The nature of the so-formed aggregates changes dramatically from inverted vesicles (toluene) to inverted micelles (hexane). The size of the aggregates was determined using dynamic light scattering. Atomic force microscopy allowed us to study the dry structure of the vesicles on a glass surface.

Dynamic Passage of Topography Beneath the Southern Costa Rica Forearc seen with Seismic Stratigraphy

NASA Astrophysics Data System (ADS)

Edwards, J. H.; Kluesner, J. W.; Silver, E. A.

2014-12-01

3D seismic reflection data (CRISP) collected across the southern Costa Rica margin reveals that a thick, deforming sedimentary wedge underlies the younger slope sediments (Silver et al., this meeting). The older wedge material and younger slope sediments are separated by a high-amplitude regional unconformity. Seismic stratigraphy of the sedimentary strata overlying this regional unconformity reflects a dynamic deformation history of the margin. The younger slope sediments contain series of more localized unconformities, separating sedimentary units as thick as 1 km that reveal a dynamically changing set of inverted, overlapping basins. The geometry of these overlapping, inverted basins indicate sequential uplift events. The direction of basin thickening varies upsection, and these basins are cut by both thrust and normal faults and are deformed by folding. Structural development appears to be controlled by relief on the subducting plate interface, which induces uplift and subsidence and thereby controls the pattern of erosion and deposition. We interpret the evolution of these inverted stratigraphic packages as forming from subducting topography. Correlating these seismic-stratigraphic packages to recent drilling based on preliminary magnetostratigraphy from IODP site U1413 (Expedition 344 Scientists, 2013), allows us to date the passage of the subducting plate topography beginning ~2 Ma.

Electronic structures of GeSi nanoislands grown on pit-patterned Si(001) substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Han, E-mail: Dabombyh@aliyun.com; Yu, Zhongyuan

2014-11-15

Patterning pit on Si(001) substrate prior to Ge deposition is an important approach to achieve GeSi nanoislands with high ordering and size uniformity. In present work, the electronic structures of realistic uncapped pyramid, dome, barn and cupola nanoislands grown in (105) pits are systematically investigated by solving Schrödinger equation for heavy-hole, which resorts to inhomogeneous strain distribution and nonlinear composition-dependent band parameters. Uniform, partitioned and equilibrium composition profile (CP) in nanoisland and inverted pyramid structure are simulated separately. We demonstrate the huge impact of composition profile on localization of heavy-hole: wave function of ground state is confined near pit facetsmore » for uniform CP, at bottom of nanoisland for partitioned CP and at top of nanoisland for equilibrium CP. Moreover, such localization is gradually compromised by the size effect as pit filling ratio or pit size decreases. The results pave the fundamental guideline of designing nanoislands on pit-patterned substrates for desired applications.« less

Assessing Diversity of DNA Structure-Related Sequence Features in Prokaryotic Genomes

PubMed Central

Huang, Yongjie; Mrázek, Jan

2014-01-01

Prokaryotic genomes are diverse in terms of their nucleotide and oligonucleotide composition as well as presence of various sequence features that can affect physical properties of the DNA molecule. We present a survey of local sequence patterns which have a potential to promote non-canonical DNA conformations (i.e. different from standard B-DNA double helix) and interpret the results in terms of relationships with organisms' habitats, phylogenetic classifications, and other characteristics. Our present work differs from earlier similar surveys not only by investigating a wider range of sequence patterns in a large number of genomes but also by using a more realistic null model to assess significant deviations. Our results show that simple sequence repeats and Z-DNA-promoting patterns are generally suppressed in prokaryotic genomes, whereas palindromes and inverted repeats are over-represented. Representation of patterns that promote Z-DNA and intrinsic DNA curvature increases with increasing optimal growth temperature (OGT), and decreases with increasing oxygen requirement. Additionally, representations of close direct repeats, palindromes and inverted repeats exhibit clear negative trends with increasing OGT. The observed relationships with environmental characteristics, particularly OGT, suggest possible evolutionary scenarios of structural adaptation of DNA to particular environmental niches. PMID:24408877

Highly tunable local gate controlled complementary graphene device performing as inverter and voltage controlled resistor.

PubMed

Kim, Wonjae; Riikonen, Juha; Li, Changfeng; Chen, Ya; Lipsanen, Harri

2013-10-04

Using single-layer CVD graphene, a complementary field effect transistor (FET) device is fabricated on the top of separated back-gates. The local back-gate control of the transistors, which operate with low bias at room temperature, enables highly tunable device characteristics due to separate control over electrostatic doping of the channels. Local back-gating allows control of the doping level independently of the supply voltage, which enables device operation with very low VDD. Controllable characteristics also allow the compensation of variation in the unintentional doping typically observed in CVD graphene. Moreover, both p-n and n-p configurations of FETs can be achieved by electrostatic doping using the local back-gate. Therefore, the device operation can also be switched from inverter to voltage controlled resistor, opening new possibilities in using graphene in logic circuitry.

Mathematical model for the dc-ac inverter for the Space Shuttle

NASA Technical Reports Server (NTRS)

Berry, Frederick C.

1987-01-01

The reader is informed of what was done for the mathematical modeling of the dc-ac inverter for the Space Shuttle. The mathematical modeling of the dc-ac inverter is an essential element in the modeling of the electrical power distribution system of the Space Shuttle. The electrical power distribution system which is present on the Space Shuttle is made up to 3 strings each having a fuel cell which provides dc to those systems which require dc, and the inverters which convert the dc to ac for those elements which require ac. The inverters are units which are 2 wire structures for the main dc inputs and 2 wire structures for the ac output. When 3 are connected together a 4 wire wye connection results on the ac side. The method of modeling is performed by using a Least Squares curve fitting method. A computer program is presented for implementation of the model along with graphs and tables to demonstrate the accuracy of the model.

On an efficient multilevel inverter assembly: structural savings and design optimisations

NASA Astrophysics Data System (ADS)

Choupan, Reza; Nazarpour, Daryoush; Golshannavaz, Sajjad

2018-01-01

This study puts forward an efficient unit cell to be taken in use in multilevel inverter assemblies. The proposed structure is in line with reductions in number of direct current (dc) voltage sources, insulated-gate bipolar transistors (IGBTs), gate driver circuits, installation area, and hence the implementation costs. Such structural savings do not sacrifice the technical performance of the proposed design wherein an increased number of output voltage levels is attained, interestingly. Targeting a techno-economic characteristic, the contemplated structure is included as the key unit of cascaded multilevel inverters. Such extensions require development of applicable design procedures. To this end, two efficient strategies are elaborated to determine the magnitudes of input dc voltage sources. As well, an optimisation process is developed to explore the optimal allocation of different parameters in overall performance of the proposed inverter. These parameters are investigated as the number of IGBTs, dc sources, diodes, and overall blocked voltage on switches. In the lights of these characteristics, a comprehensive analysis is established to compare the proposed design with the conventional and recently developed structures. Detailed simulation and experimental studies are conducted to assess the performance of the proposed design. The obtained results are discussed in depth.

Multilayer densities using a wavelet-based gravity method and their tectonic implications beneath the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xu, Chuang; Luo, Zhicai; Sun, Rong; Zhou, Hao; Wu, Yihao

2018-06-01

Determining density structure of the Tibetan Plateau is helpful in better understanding of tectonic structure and development. Seismic method, as traditional approach obtaining a large number of achievements of density structure in the Tibetan Plateau except in the centre and west, is primarily inhibited by the poor seismic station coverage. As the implementation of satellite gravity missions, gravity method is more competitive because of global homogeneous gravity coverage. In this paper, a novel wavelet-based gravity method with high computation efficiency and excellent local identification capability is developed to determine multilayer densities beneath the Tibetan Plateau. The inverted six-layer densities from 0 to 150 km depth can reveal rich tectonic structure and development of study area: (1) The densities present a clockwise pattern, nearly east-west high-low alternating pattern in the west and nearly south-north high-low alternating pattern in the east, which is almost perpendicular to surface movement direction relative to the stable Eurasia from the Global Positioning System velocity field; (2) Apparent fold structure approximately from 10 to 110 km depth can be inferred from the multilayer densities, the deformational direction of which is nearly south-north in the west and east-west in the east; (3) Possible channel flows approximately from 30 to 110 km depth can also be observed clearly during the multilayer densities. Moreover, the inverted multilayer densities are in agreement with previous studies, which verify the correctness and effectiveness of our method.

Multilayer Densities Using a Wavelet-based Gravity Method and Their Tectonic Implications beneath the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xu, Chuang; Luo, Zhicai; Sun, Rong; Zhou, Hao; Wu, Yihao

2018-03-01

Determining density structure of the Tibetan Plateau is helpful in better understanding tectonic structure and development. Seismic method, as traditional approach obtaining a large number of achievements of density structure in the Tibetan Plateau except in the center and west, is primarily inhibited by the poor seismic station coverage. As the implementation of satellite gravity missions, gravity method is more competitive because of global homogeneous gravity coverage. In this paper, a novel wavelet-based gravity method with high computation efficiency and excellent local identification capability is developed to determine multilayer densities beneath the Tibetan Plateau. The inverted 6-layer densities from 0 km to 150 km depth can reveal rich tectonic structure and development of study area: (1) The densities present a clockwise pattern, nearly east-west high-low alternating pattern in the west and nearly south-north high-low alternating pattern in the east, which is almost perpendicular to surface movement direction relative to the stable Eurasia from the Global Positioning System velocity field; (2) Apparent fold structure approximately from 10 km to 110 km depth can be inferred from the multilayer densities, the deformational direction of which is nearly south-north in the west and east-west in the east; (3) Possible channel flows approximately from 30 km to 110 km depth can be also observed clearly during the multilayer densities. Moreover, the inverted multilayer densities are in agreement with previous studies, which verify the correctness and effectiveness of our method.

Anomalous electron collimation in HgTe quantum wells with inverted band structure.

PubMed

Zou, Y L; Zhang, L B; Song, J T

2013-02-20

We investigate the electron collimation behavior in HgTe quantum wells (QWs) with a magnetic-electric barrier induced by a ferromagnetic metal stripe. We find that electrons can transmit perfectly through the magnetic-electric barrier at some specific incidence angles. These angles can be controlled by the tuning gate voltage, local magnetic field and Fermi energy of incident electrons in QWs with appropriate barrier length. This collimation feature can be used to construct momentum filters in HgTe QWs and has potential application in nanodevices.

One dimensional P wave velocity structure of the crust beneath west Java and accurate hypocentre locations from local earthquake inversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Supardiyono; Santosa, Bagus Jaya; Physics Department, Faculty of Mathematics and Natural Sciences, Sepuluh Nopember Institute of Technology, Surabaya

A one-dimensional (1-D) velocity model and station corrections for the West Java zone were computed by inverting P-wave arrival times recorded on a local seismic network of 14 stations. A total of 61 local events with a minimum of 6 P-phases, rms 0.56 s and a maximum gap of 299 Degree-Sign were selected. Comparison with previous earthquake locations shows an improvement for the relocated earthquakes. Tests were carried out to verify the robustness of inversion results in order to corroborate the conclusions drawn out from our reasearch. The obtained minimum 1-D velocity model can be used to improve routine earthquakemore » locations and represents a further step toward more detailed seismotectonic studies in this area of West Java.« less

High-speed all-optical logic inverter based on stimulated Raman scattering in silicon nanocrystal.

PubMed

Sen, Mrinal; Das, Mukul K

2015-11-01

In this paper, we propose a new device architecture for an all-optical logic inverter (NOT gate), which is cascadable with a similar device. The inverter is based on stimulated Raman scattering in silicon nanocrystal waveguides, which are embedded in a silicon photonic crystal structure. The Raman response function of silicon nanocrystal is evaluated to explore the transfer characteristic of the inverter. A maximum product criterion for the noise margin is taken to analyze the cascadability of the inverter. The time domain response of the inverter, which explores successful inversion operation at 100 Gb/s, is analyzed. Propagation delay of the inverter is on the order of 5 ps, which is less than the delay in most of the electronic logic families as of today. Overall dimension of the device is around 755  μm ×15  μm, which ensures integration compatibility with the matured silicon industry.

Novel nano-OLED based probes for very high resolution optical microscopy

NASA Astrophysics Data System (ADS)

Zhao, Yiying

Near-field scanning optical microscopy (NSOM) has been applied in the study of nanomaterials, microelectronics, photonics, plasmonics, cells, and molecules. However, conventional NSOM relies on optically pumped probes, suffering low optical transmission, heating of the tip, and poor reproducibility of probe fabrication, increasing the cost, impeding usability, reducing practical imaging resolution, and limiting NSOM's utility. In this thesis, I demonstrate a novel probe based on a nanoscale, electrically pumped organic light-emitting device (OLED) formed on the tip of a low-cost, commercially available atomic force microscopy (AFM) probe. I describe the structure, fabrication, and principles of this novel probe's operation, and discuss its potential to overcome the limitations of conventional NSOM probes. The broader significance of this work in the field of organic optoelectronics is also discussed. Briefly, OLEDs consist of organic thin films sandwiched between two electrodes. Under bias, electrons and holes are injected into the organic layers, leading to radiative recombination. Depositing a small molecular OLED in vacuum onto a pyramid-tipped AFM probe results in a laminar structure that is highly curved at the tip. Simple electrical modeling predicts concentration of electric field and localized electron injection into the organic layers at the tip, improving the local charge balance in an otherwise electron-starved OLED. Utilizing an "inverted" OLED structure (i.e. cathode on the "bottom"), light emission is localized to sub-200 nm sized, green light emitting regions on probe vertices; light output power in the range of 0.1-0.5 nanowatts was observed, comparable to that of typical fiber based NSOM probes but with greater power efficiency. Massive arrays of similar sub-micron OLEDs were also fabricated by depositing onto textured silicon substrates, demonstrating the superior scalability of the probe fabrication process (e.g. relative to pulled glass fibers). The investigation of the effect of non-planar substrate geometry on charge injection, transport and recombination provides broader insights into OLEDs made on rough substrates, general understanding of OLED operation (e.g. filamentary charge conduction) and degradation, and potentially helps to improve technologically important "inverted" OLED structures.

Fast large-scale object retrieval with binary quantization

NASA Astrophysics Data System (ADS)

Zhou, Shifu; Zeng, Dan; Shen, Wei; Zhang, Zhijiang; Tian, Qi

2015-11-01

The objective of large-scale object retrieval systems is to search for images that contain the target object in an image database. Where state-of-the-art approaches rely on global image representations to conduct searches, we consider many boxes per image as candidates to search locally in a picture. In this paper, a feature quantization algorithm called binary quantization is proposed. In binary quantization, a scale-invariant feature transform (SIFT) feature is quantized into a descriptive and discriminative bit-vector, which allows itself to adapt to the classic inverted file structure for box indexing. The inverted file, which stores the bit-vector and box ID where the SIFT feature is located inside, is compact and can be loaded into the main memory for efficient box indexing. We evaluate our approach on available object retrieval datasets. Experimental results demonstrate that the proposed approach is fast and achieves excellent search quality. Therefore, the proposed approach is an improvement over state-of-the-art approaches for object retrieval.

Maximizing RNA folding rates: a balancing act.

PubMed Central

Thirumalai, D; Woodson, S A

2000-01-01

Large ribozymes typically require very long times to refold into their active conformation in vitro, because the RNA is easily trapped in metastable misfolded structures. Theoretical models show that the probability of misfolding is reduced when local and long-range interactions in the RNA are balanced. Using the folding kinetics of the Tetrahymena ribozyme as an example, we propose that folding rates are maximized when the free energies of forming independent domains are similar to each other. A prediction is that the folding pathway of the ribozyme can be reversed by inverting the relative stability of the tertiary domains. This result suggests strategies for optimizing ribozyme sequences for therapeutics and structural studies. PMID:10864039

Electroluminescence of fluorescent-phosphorescent organic light-emitting diodes with regular, inverted, and symmetrical structures

NASA Astrophysics Data System (ADS)

Yang, Su-Hua; Shih, Po-Jen; Wu, Wen-Jie

2014-11-01

The influence of the device structure on the electroluminescence (EL) properties of fluorescent-phosphorescent organic light emitting diodes (OLEDs) was demonstrated. Four devices with regular-, inverted-, compensated- and symmetrical-emission layers (EMLs) were prepared. In regular-EML device, DCJTB emission increased when the phosphorescent sensitized EML was thickened. In inverted-EML device, low electron energy barrier at the Bphen/BCzVB interface resulted in weakened blue emission. The compensated-EML device, prepared with a red color-compensated layer, showed a color-tunable broadband white emission. Conversely, device with a quantum-like symmetrical-EML showed a narrow color-temperature range. Stable EL efficiency was obtained from regular, compensated, and symmetrical-EML devices. In contrast, EL efficiency of inverted-EML device rolled off significantly, though it had the highest EL efficiency of 11.4 cd/A.

Recent Advances in Subsurface Imaging and Monitoring with Active Sources in China

NASA Astrophysics Data System (ADS)

Wang, B.; Chen, Y.; Wang, W.; Yang, W.

2017-12-01

Imaging high-resolution crustal structures and monitoring their temporal changes with active sources is essential to our understanding of regional tectonics and seismic hazards. In the past decades, great efforts has been made in China to looking for an ideal artificial seismic source to study continental crustal structures. After a mountain of field experiments, we developed permanent and portable seismic airgun sources for inland seismotectonic studies. Here we introduce several applications of using airgun source to imaging local crustal structures and monitoring velocity changes associated with natural and anthropogenic loadings. During Oct. 10th-20th, 2015, we carried out a crustal structure exploration experiment by firing portable airgun source along the Yangtze River in Anhui Province of eastern China. About 5000 shots were fired along 300km long section of the river. More than 2000 portable short period seismometers or geophones were deployed during the experiment. About 3000 of 5000 shots were fired at 20 fixed sites roughly evenly distributed along the river, and the rest shots were fired in the walkway. Seismic signal radiated by airgun source can be tracked to 350km. 2D/3D near surface and crustal velocity structure along the Yangtze River and adjacent region were inverted from airgun seismic records. Inverted velocity show well consistence with previous images and geological structure. The high resolution structural image provides a better understanding on regional geologic features and distribution of mineral resources. In the past five years, three Fixed Aigun Signal Transmitting Stations (FASTS) were built in western China. Those FASTS generate seismic signals with high repeatability, which can be tracked to the distance 1300 km. The highly reproducible signals are used to monitor the subtle subsurface changes. Observed diurnal and semi-diurnal velocity changes 10-4 are supposed to be results of barometrical and tidal loading. Suspicious velocity changes prior to several moderate earthquakes are detected around. Seismic velocity measured around the Hutubi underground gas storage show clear correlation with the gas pressure. Those results shed some light on the short term evolution of the shallow to low crust, which may boost our understanding the mechanism of local seismic hazards.

Inverted temperature sequences: role of deformation partitioning

NASA Astrophysics Data System (ADS)

Grujic, D.; Ashley, K. T.; Coble, M. A.; Coutand, I.; Kellett, D.; Whynot, N.

2015-12-01

The inverted metamorphism associated with the Main Central thrust zone in the Himalaya has been historically attributed to a number of tectonic processes. Here we show that there is actually a composite peak and deformation temperature sequence that formed in succession via different tectonic processes. The deformation partitioning seems to the have played a key role, and the magnitude of each process has varied along strike of the orogen. To explain the formation of the inverted metamorphic sequence across the Lesser Himalayan Sequence (LHS) in eastern Bhutan, we used Raman spectroscopy of carbonaceous material (RSCM) to determine the peak metamorphic temperatures and Ti-in-quartz thermobarometry to determine the deformation temperatures combined with thermochronology including published apatite and zircon U-Th/He and fission-track data and new 40Ar/39Ar dating of muscovite. The dataset was inverted using 3D-thermal-kinematic modeling to constrain the ranges of geological parameters such as fault geometry and slip rates, location and rates of localized basal accretion, and thermal properties of the crust. RSCM results indicate that there are two peak temperature sequences separated by a major thrust within the LHS. The internal temperature sequence shows an inverted peak temperature gradient of 12 °C/km; in the external (southern) sequence, the peak temperatures are constant across the structural sequence. Thermo-kinematic modeling suggest that the thermochronologic and thermobarometric data are compatible with a two-stage scenario: an Early-Middle Miocene phase of fast overthrusting of a hot hanging wall over a downgoing footwall and inversion of the synkinematic isotherms, followed by the formation of the external duplex developed by dominant underthrusting and basal accretion. To reconcile our observations with the experimental data, we suggest that pervasive ductile deformation within the upper LHS and along the Main Central thrust zone at its top stopped at ~11 Ma at which time the deformation shifted and focused within the external duplex and the Main Boundary Thrust.

Inverted base pavements : new field test and design catalogue.

DOT National Transportation Integrated Search

2014-01-01

The current economic situation has severely affected the US road infrastructure and funding has become : inadequate for either maintenance or future growth. : The inverted base pavement structure is a promising alternative to achieve high quality roa...

Japanese power electronics inverter technology and its impact on the American air conditioning industry

NASA Astrophysics Data System (ADS)

Ushimaru, Kenji

1990-08-01

Since 1983, technological advances and market growth of inverter-driven variable-speed heat pumps in Japan have been dramatic. The high level of market penetration was promoted by a combination of political, economic, and trade policies in Japan. A unique environment was created in which the leading domestic industries, microprocessor manufacturing, compressors for air conditioning and refrigerators, and power electronic devices, were able to direct the development and market success of inverter-driven heat pumps. As a result, leading U.S. variable-speed heat pump manufacturers should expect a challenge from the Japanese producers of power devices and microprocessors. Because of the vertically-integrated production structure in Japan, in contrast to the out-sourcing culture of the United States, price competition at the component level (such as inverters, sensors, and controls) may impact the structure of the industry more severely than final product sales.

InGaP/GaAs Inverted Dual Junction Solar Cells For CPV Applications Using Metal-Backed Epitaxial Lift-Off

NASA Astrophysics Data System (ADS)

Bauhuis, Gerard J.; Mulder, Peter; Haverkamp, Erik J.; Schermer, John J.; Nash, Lee J.; Fulgoni, Dominic J. F.; Ballard, Ian M.; Duggan, Geoffrey

2010-10-01

The epitaxial lift-off (ELO) technique has been combined with inverted III-V PV cell epitaxial growth with the aim of employing thin film PV cells in HCPV systems. In a stepwise approach to the realization of an inverted triple junction on a MELO platform we have first grown a GaAs single junction PV cell to establish the basic layer release process and cell processing steps followed by the growth, fabrication and test of an inverted InGaP/GaAs dual junction structure.

Development of the morphology during functional stack build-up of P3HT:PCBM bulk heterojunction solar cells with inverted geometry.

PubMed

Wang, Weijia; Pröller, Stephan; Niedermeier, Martin A; Körstgens, Volker; Philipp, Martine; Su, Bo; Moseguí González, Daniel; Yu, Shun; Roth, Stephan V; Müller-Buschbaum, Peter

2015-01-14

Highly efficient poly(3-hexylthiophene-2,5-diyl) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells are achieved by using an inverted geometry. The development of the morphology is investigated as a function of the multilayer stack assembling during the inverted solar cell preparation. Atomic force microscopy is used to reveal the surface morphology of each stack, and the inner structure is probed with grazing incidence small-angle X-ray scattering. It is found that the smallest domain size of P3HT is introduced by replicating the fluorine-doped tin oxide structure underneath. The structure sizes of the P3HT:PCBM active layer are further optimized after thermal annealing. Compared to devices with standard geometry, the P3HT:PCBM layer in the inverted solar cells shows smaller domain sizes, which are much closer to the exciton diffusion length in the polymer. The decrease in domain sizes is identified as the main reason for the improvement of the device performance.

Cascaded Converters for Integration and Management of Grid Level Energy Storage Systems

NASA Astrophysics Data System (ADS)

Alaas, Zuhair

This research work proposes two cascaded multilevel inverter structures for BESS. The gating and switching control of switching devices in both inverter typologies are done by using a phase-shifted PWM scheme. The first proposed isolated multilevel inverter is made up of three-phase six-switch inverter blocks with a reduced number of power components compared with traditional isolated CHB. The suggested isolated converter has only one battery string for three-phase system that can be used for high voltage and high power applications such as grid connected BESS and alternative energy systems. The isolated inverter enables dq frame based simple control and eliminates the issues of single-phase pulsating power, which can cause detrimental impacts on certain dc sources. Simulation studies have been carried out to compare the proposed isolated multi-level inverter with an H-bridge cascaded transformer inverter. The simulation results verified the performance of the isolated inverter. The second proposed topology is a Hierarchal Cascaded Multilevel Converter (HCMC) with phase to phase SOC balancing capability which also for high voltage and high power battery energy storage systems. The HCMC has a hybrid structure of half-bridge converters and H-bridge inverters and the voltage can be hierarchically cascaded to reach the desired value at the half-bridge and the H-bridge levels. The uniform SOC battery management is achieved by controlling the half-bridge converters that are connected to individual battery modules/cells. Simulation studies and experimental results have been carried on a large scale battery system under different operating conditions to verify the effectiveness of the proposed inverters. Moreover, this dissertation presents a new three-phase SOC equalizing circuit, called six-switch energy-level balancing circuit (SSBC), which can be used to realize uniform SOC operation for full utilization of the battery capacity in proposed HCMC or any CMI inverter while keeping balanced three-phase operation. A sinusoidal PWM modulation technique is used to control power transferring between phases. Simulation results have been carried out to verify the performance of the proposed SSBC circuit of uniform three-phase SOC balancing.

Selective harmonic elimination strategy in eleven level inverter for PV system with unbalanced DC sources

NASA Astrophysics Data System (ADS)

Ghoudelbourk, Sihem.; Dib, D.; Meghni, B.; Zouli, M.

2017-02-01

The paper deals with the multilevel converters control strategy for photovoltaic system integrated in distribution grids. The objective of the proposed work is to design multilevel inverters for solar energy applications so as to reduce the Total Harmonic Distortion (THD) and to improve the power quality. The multilevel inverter power structure plays a vital role in every aspect of the power system. It is easier to produce a high-power, high-voltage inverter with the multilevel structure. The topologies of multilevel inverter have several advantages such as high output voltage, lower total harmonic distortion (THD) and reduction of voltage ratings of the power semiconductor switching devices. The proposed control strategy ensures an implementation of selective harmonic elimination (SHE) modulation for eleven levels. SHE is a very important and efficient strategy of eliminating selected harmonics by judicious selection of the firing angles of the inverter. Harmonics elimination technique eliminates the need of the expensive low pass filters in the system. Previous research considered that constant and equal DC sources with invariant behavior; however, this research extends earlier work to include variant DC sources, which are typical of lead-acid batteries when used in system PV. This Study also investigates methods to minimize the total harmonic distortion of the synthesized multilevel waveform and to help balance the battery voltage. The harmonic elimination method was used to eliminate selected lower dominant harmonics resulting from the inverter switching action.

Paleo-hydraulic Reconstructions of Topographically Inverted River Deposits on Earth and Mars

NASA Astrophysics Data System (ADS)

Hayden, A.; Lamb, M. P.; Fischer, W. W.; Ewing, R. C.; McElroy, B. J.

2015-12-01

River deposits are one of the keys to understanding the history of flowing water and sediment on Earth and Mars. Deposits of some ancient Martian rivers have been topographically inverted resulting in sinuous ridges visible from orbit. However, it is unclear what aspects of the fluvial deposits these ridges represent, so reconstructing paleo-hydraulics from ridge geometry is complicated. Most workers have assumed that ridges represent casts of paleo-river channels, such that ridge widths and slopes, for example, can be proxies for river widths and slopes at some instant in time. Alternatively, ridges might reflect differential erosion of extensive channel bodies, and therefore preserve a rich record of channel conditions and paleoenvironment over time. To explore these hypotheses, we examined well exposed inverted river deposits in the Jurassic Morrison and Early Cretaceous Cedar Mountain Formations across the San Rafael Swell of central Utah. We mapped features on foot and by UAV, measured stratigraphic sections and sedimentary structures to constrain deposit architecture and river paleo-hydraulics, and used field observations and drainage network analyses to constrain recent erosion. Our work partly confirms earlier work in that the local trend of the ridge axis generally parallels paleo-flow indicators. However, ridge relief is much greater than reconstructed channel depths, and ridge widths vary from zero to several times the reconstructed channel width. Ridges instead appear to record a rich history of channel lateral migration, floodplain deposition, and soil development over significant time. The ridge network is disjointed owing to active modern fluvial incision and scarp retreat. Our results suggest that ridge geometry alone contains limited quantitative information about paleo-rivers, and that stratigraphic sections and observations of sedimentary structures within ridge-forming deposits are necessary to constrain ancient river systems on Mars.

Total variation regularization for seismic waveform inversion using an adaptive primal dual hybrid gradient method

NASA Astrophysics Data System (ADS)

Yong, Peng; Liao, Wenyuan; Huang, Jianping; Li, Zhenchuan

2018-04-01

Full waveform inversion is an effective tool for recovering the properties of the Earth from seismograms. However, it suffers from local minima caused mainly by the limited accuracy of the starting model and the lack of a low-frequency component in the seismic data. Because of the high velocity contrast between salt and sediment, the relation between the waveform and velocity perturbation is strongly nonlinear. Therefore, salt inversion can easily get trapped in the local minima. Since the velocity of salt is nearly constant, we can make the most of this characteristic with total variation regularization to mitigate the local minima. In this paper, we develop an adaptive primal dual hybrid gradient method to implement total variation regularization by projecting the solution onto a total variation norm constrained convex set, through which the total variation norm constraint is satisfied at every model iteration. The smooth background velocities are first inverted and the perturbations are gradually obtained by successively relaxing the total variation norm constraints. Numerical experiment of the projection of the BP model onto the intersection of the total variation norm and box constraints has demonstrated the accuracy and efficiency of our adaptive primal dual hybrid gradient method. A workflow is designed to recover complex salt structures in the BP 2004 model and the 2D SEG/EAGE salt model, starting from a linear gradient model without using low-frequency data below 3 Hz. The salt inversion processes demonstrate that wavefield reconstruction inversion with a total variation norm and box constraints is able to overcome local minima and inverts the complex salt velocity layer by layer.

3'-UTR-located inverted Alu repeats facilitate mRNA translational repression and stress granule accumulation

PubMed Central

Fitzpatrick, Terry; Huang, Sui

2012-01-01

Alu repeats within human genes may potentially alter gene expression. Here, we show that 3′-UTR-located inverted Alu repeats significantly reduce expression of an AcGFP reporter gene. Mutational analysis demonstrates that the secondary structure, but not the primary nucleotide sequence, of the inverted Alu repeats is critical for repression. The expression levels and nucleocytoplasmic distribution of reporter mRNAs with or without 3′-UTR inverted Alu repeats are similar; suggesting that reporter gene repression is not due to changes in mRNA levels or mRNA nuclear sequestration. Instead, reporter gene mRNAs harboring 3′-UTR inverted Alu repeats accumulate in cytoplasmic stress granules. These findings may suggest a novel mechanism whereby 3′-UTR-located inverted Alu repeats regulate human gene expression through sequestration of mRNAs within stress granules. PMID:22688648

Anisotropic properties of periodically polarity-inverted zinc oxide structures

NASA Astrophysics Data System (ADS)

Park, J. S.; Minegishi, T.; Lee, J. W.; Hong, S. K.; Song, J. H.; Lee, J. Y.; Yoon, E.; Yao, T.

2010-06-01

We report on the anisotropic structural properties of periodically polarity-inverted (PPI) ZnO structures grown on patterned templates. The etching and growth rates along ⟨112¯0⟩ direction of ZnO structures are higher than those of ⟨101¯0⟩ direction of ZnO films. From the strain evaluation by Raman spectroscopy, compressive strains are observed in all PPI ZnO samples with different stripe pattern size and the smaller pattern size is more effective to residual stress relaxation. The detailed structures at transition region show relationship with the anisotropic crystal quality.

Effects of three-dimensional velocity structure on the seismicity of the 1984 Morgan Hill, California, aftershock sequence

USGS Publications Warehouse

Michael, A.J.

1988-01-01

A three-dimensional velocity model for the area surrounding the 24 April 1984 Morgan Hill earthquake has been developed by simultaneously inverting local earthquake and refraction arrival-time data. This velocity model corresponds well to the surface geology of the region, predominantly showing a low-velocity region associated with the sedimentary sequence to the south-west of the Madrone Springs fault. The focal mechanisms were also determined for 946 earthquakes using both the one-dimensional and three-dimensional earth models. Both earth models yield similar focal mechanisms for these earthquakes. -from Author

Power and temperature dependent photoluminescence investigation of the linear polarization at normal and inverted interface transitions in InP/InAlAs and InGaAsP/InAlAs QW structures

NASA Astrophysics Data System (ADS)

Esmaielpour, Hamidreza; Whiteside, Vincent R.; Hirst, Louise C.; Forbes, David V.; Walters, Robert J.; Sellers, Ian R.

We present an investigation of the interface effects for InGaAsP/InAlAs QW and InP/InAlAs QW structures capped with an InP layer. Continuous wave photoluminescence (PL) spectroscopy of these samples at 4 K shows features associated with the interfaces of an InAlAs layer grown on an InP layer (normal interface) and an InP layer grown on an InAlAs material (inverted interface). Power dependent PL of the InGaAsP QW indicates that there are two features related to the inverted interface, whereby the linear polarization of one increases and for the other decreases. In addition, a temperature dependent study of this sample shows that as the temperature increases: the linear polarization for both features decreases; at room temperature, there is negligible polarization effect. A power dependent PL study of the InP QW structure shows both normal and inverted interface transitions have opposing trends in linear polarization. Notably, the temperature dependent PL investigation displays a reduction of polarization degree for the inverted interface: as expected; while an increase of polarization for the normal interface was observed. In addition, power and temperature dependence of peak energy of the interface transitions for both samples will be presented.

Leakage current suppression with a combination of planarized gate and overlap/off-set structure in metal-induced laterally crystallized polycrystalline-silicon thin-film transistors

NASA Astrophysics Data System (ADS)

Chae, Hee Jae; Seok, Ki Hwan; Lee, Sol Kyu; Joo, Seung Ki

2018-04-01

A novel inverted staggered metal-induced laterally crystallized (MILC) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) with a combination of a planarized gate and an overlap/off-set at the source-gate/drain-gate structure were fabricated and characterized. While the MILC process is advantageous for fabricating inverted staggered poly-Si TFTs, MILC TFTs reveal higher leakage current than TFTs crystallized by other processes due to their high trap density of Ni contamination. Due to this drawback, the planarized gate and overlap/off-set structure were applied to inverted staggered MILC TFTs. The proposed device shows drastic suppression of leakage current and pinning phenomenon by reducing the lateral electric field and the space-charge limited current from the gate to the drain.

Simulation of current-voltage curves for inverted planar structure perovskite solar cells using equivalent circuit model with inductance

NASA Astrophysics Data System (ADS)

Cojocaru, Ludmila; Uchida, Satoshi; Jayaweera, Piyankarage V. V.; Kaneko, Shoji; Toyoshima, Yasutake; Nakazaki, Jotaro; Kubo, Takaya; Segawa, Hiroshi

2017-02-01

Physical modeling of hysteretic behavior in current-voltage (I-V) curves of perovskite solar cells (PSCs) is necessary for further improving their power conversion efficiencies (PCEs). The reduction of hysteresis in inverted planar structure PSCs (p-PSCs) has been achieved by using a [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) layer. In the cases, the opposite trend of the I-V hysteresis has been observed where the forward scan shows slightly higher efficiency than the reverse scan. In this paper, an equivalent circuit model with inductance is proposed. This model consists of a Schottky diode involving a parasitic inductance focusing PCBM/Al(Ca) interface and accurately represents the opposite trend of the I-V hysteresis of the p-PSC with an inverted structure.

SU8 inverted-rib waveguide Bragg grating filter.

PubMed

Huang, Cheng-Sheng; Wang, Wei-Chih

2013-08-01

A polymeric SU8 inverted-rib waveguide Bragg grating filter fabricated using reactive ion etching (RIE) and solvent assisted microcontact molding (SAMIM) is presented. SAMIM is one kind of soft lithography. The technique is unique in that a composite hard-polydimethysiloxane/polydimethysiloxane stamp is used to transfer the grating pattern onto an inverted SU8 rib waveguide system. The composite grating stamp can be used repeatedly several times without degradation. Using this stamp and inverter-rib waveguide structure, the Bragg grating filter fabrication can be significantly simplified. The experiment result shows an attenuation dip in the transmission spectra, with a value of -7 dBm at 1550 nm for a grating with a period of 0.492 μm on an inverted-rib waveguide with 6.6 μm width and 4 μm height.

Seismic tomography of northeastern Tibetan Plateau from body wave arrival times and surface wave dispersion data

NASA Astrophysics Data System (ADS)

Fang, H.; Yao, H.; Zhang, H.

2017-12-01

Reliable crustal and upper mantle structure is important to understand expansion of material from the Tibetan plateau to its northeastern margin. Previous studies have used either ambient noise tomography or body wave traveltime tomography to obtain the crustal velocity models in northeastern Tibetan Plateau. However, clear differences appear in these models obtained using different datasets. Here we propose to jointly invert local and teleseismic body wave arrival times and surface wave dispersion data from ambient noise cross correlation to obtain a unified P and S wavespeed model of the crust and upper mantle in NE Tibetan Plateau. Following Fang et al. (2016), we adopt the direct inversion strategy for surface wave data (Fang et al., 2015), which eliminates the need to construct the phase/group velocity maps and allows the straightforward incorporation of surface wave dispersion data into the body wave inversion framework. For body wave data including both local and teleseismic arrival times, we use the fast marching method (Rawlinson et al., 2004) in order to trace multiple seismic phases simultaneously. The joint inversion method takes advantage of the complementary strengths of different data types, with local body wave data constraining more on the P than S wavespeed in the crust, surface wave data most sensitive to S wavespeed in the crust and upper mantle, teleseismic body wave data resolving the upper mantle structure. A series of synthetic tests will be used to show the robustness and superiority of the joint inversion method. Besides, the inverted model will be validated by waveform simulation and comparison with other studies, like receiver function imaging. The resultant P and S wavespeed models, as well as the derived Vp/Vs model, will be essential to understand the regional tectonics of the northeastern Tibetan Plateau, and to address the related geodynamic questions of the Tibetan Plateau formation and expansion.

Lithospheric Structure of Greenland from Ambient Noise and Earthquake Surface Wave Tomography

NASA Astrophysics Data System (ADS)

Pourpoint, M.; Anandakrishnan, S.; Ammon, C. J.

2017-12-01

We present a high resolution seismic tomography model of Greenland's lithosphere from surface wave analysis. Regional and teleseismic events recorded by GLISN over the last 20 years were used. We developed a new group velocity correction method to alleviate the limitations of the sparse network and the relatively few local events. The global dispersion model GDM52 was used to calculate group delays from the earthquake to the boundaries of our study area. To better constrain the crustal structure of Greenland and cross-validate our group velocity correction approach, we also collected and processed several years of ambient noise data. An iterative reweighted generalized least-square scheme was used to invert for the group velocity maps and a Markov chain Monte Carlo technique was applied to invert for a 3-D shear wave velocity model of Greenland up to a depth of 200 km. Our shear wave velocity model is consistent with previous studies but of higher resolution and we show that in regions with limited station coverage and local seismicity, we can rely on global models to construct relatively large local data sets that can provide some important constraints on regional structures. Our model contains the signature of known geological features and reveals three prominent anomalies: a shallow low-velocity anomaly between central-eastern and northeastern Greenland that correlates well with a previously measured high geothermal heat flux; a deep high-velocity anomaly extending from southwestern to northwestern Greenland that could be interpreted as the signature of a thick Archean keel; and a deep low-velocity anomaly in central-eastern Greenland that could be associated with lithospheric thinning and upwelling of hot asthenosphere material from the rifting of the Atlantic Ocean around 60 Ma and the passage of the Icelandic mantle plume beneath Greenland between 70 and 30 Ma. Upper mantle temperature and heat flux distribution beneath Greenland are further derived from our velocity model using a grid search approach and some thermodynamic constraints. By delineating the velocity and thermal properties of these anomalies, we hope to better understand how underlying geological and geophysical processes may impact the ice sheet dynamics and influence its potential contribution to future sea level changes.

Full-waveform Inversion for Localized 3-D S-velocity Structure in D" Beneath the Caribbean using US-Array Data

NASA Astrophysics Data System (ADS)

Borgeaud, A. F. E.; Konishi, K.; Kawai, K.; Geller, R. J.

2015-12-01

The region beneath Central America is known to have significant lateral velocity heterogeneities from the upper mantle down to the lowermost mantle. It is also known for its long history of subducting oceanic plates and fragmented plate remnants that sunk to the lowermost mantle (e.g., Ren et al., 2007). In this study, we use localized full-waveform inversion to invert for the 3-D S-velocity beneath the Caribbean. We use the DSM (Kawai et al., 2006) to compute 1-D synthetic seismograms and the first-order Born approximation to compute the partial derivatives for 3-D structure. We use a larger dataset with better coverage than Kawai et al. (2014), consisting of S and ScS phases from US-Array data for events in South America. The resulting 3-D model can contribute to understanding whether the cause of the velocity anomalies is thermal, chemical, or due to phase transitions.

Reactive power and voltage control strategy based on dynamic and adaptive segment for DG inverter

NASA Astrophysics Data System (ADS)

Zhai, Jianwei; Lin, Xiaoming; Zhang, Yongjun

2018-03-01

The inverter of distributed generation (DG) can support reactive power to help solve the problem of out-of-limit voltage in active distribution network (ADN). Therefore, a reactive voltage control strategy based on dynamic and adaptive segment for DG inverter is put forward to actively control voltage in this paper. The proposed strategy adjusts the segmented voltage threshold of Q(U) droop curve dynamically and adaptively according to the voltage of grid-connected point and the power direction of adjacent downstream line. And then the reactive power reference of DG inverter can be got through modified Q(U) control strategy. The reactive power of inverter is controlled to trace the reference value. The proposed control strategy can not only control the local voltage of grid-connected point but also help to maintain voltage within qualified range considering the terminal voltage of distribution feeder and the reactive support for adjacent downstream DG. The scheme using the proposed strategy is compared with the scheme without the reactive support of DG inverter and the scheme using the Q(U) control strategy with constant segmented voltage threshold. The simulation results suggest that the proposed method has a significant improvement on solving the problem of out-of-limit voltage, restraining voltage variation and improving voltage quality.

Inverted micellar intermediates and the transitions between lamellar, cubic, and inverted hexagonal lipid phases. II. Implications for membrane-membrane interactions and membrane fusion.

PubMed Central

Siegel, D P

1986-01-01

Results of a kinetic model of thermotropic L alpha----HII phase transitions are used to predict the types and order-of-magnitude rates of interactions between unilamellar vesicles that can occur by intermediates in the L alpha----HII phase transition. These interactions are: outer monolayer lipid exchange between vesicles; vesicle leakage subsequent to aggregation; and (only in systems with ratios of L alpha and HII phase structural dimensions in a certain range or with unusually large bilayer lateral compressibilities) vesicle fusion with retention of contents. It was previously proposed that inverted micellar structures mediate membrane fusion. These inverted micellar structures are thought to form in all systems with such transitions. However, I show that membrane fusion probably occurs via structures that form from these inverted micellar intermediates, and that fusion should occur in only a sub-set of lipid systems that can adopt the HII phase. For single-component phosphatidylethanolamine (PE) systems with thermotropic L alpha----HII transitions, lipid exchange should be observed starting at temperatures several degrees below TH and at all higher temperatures, where TH is the L alpha----HII transition temperature. At temperatures above TH, the HII phase forms between apposed vesicles, and eventually ruptures them (leakage). In most single-component PE systems, fusion via L alpha----HII transition intermediates should not occur. This is the behavior observed by Bentz, Ellens, Lai, Szoka, et al. in PE vesicle systems. Fusion is likely to occur under circumstances in which multilamellar samples of lipid form the so-called "inverted cubic" or "isotropic" phase. This is as observed in the mono-methyl DOPE system (Ellens, H., J. Bentz, and F. C. Szoka. 1986. Fusion of phosphatidylethanolamine containing liposomes and the mechanism of the L alpha-HII phase transition. Biochemistry. In press.) In lipid systems with L alpha----HII transitions driven by cation binding (e.g., Ca2+-cardiolipin), fusion should be more frequent than in thermotropic systems. PMID:3719075

Management Strategies for Skull Base Inverted Papilloma.

PubMed

Grayson, Jessica W; Khichi, Sunny S; Cho, Do-Yeon; Riley, Kristen O; Woodworth, Bradford A

2016-07-01

Inverted papilloma attached to the ventral skull base presents a surgical dilemma because surgical removal of the bony pedicle is critical to decrease risk of recurrence. The objective of this study is to evaluate the effectiveness of endoscopic management of skull base inverted papilloma. Case series with planned data collection. Tertiary medical center. Patients with skull base inverted papilloma. Over 7 years, 49 patients with skull base inverted papilloma were referred for surgical resection. Demographics, operative technique, pathology, complications, recurrence, and postoperative follow-up were evaluated. Average age at presentation was 57 years. Twenty-six patients (53%) had prior attempts at resection elsewhere, and 5 had squamous cell carcinoma (SCCA) arising in an inverted papilloma. Six patients (12%) suffered major complications, including skull base osteomyelitis in 2 previously irradiated patients, cerebrospinal fluid leak with pneumocephalus (n = 1), meningitis (n = 1), invasive fungal sinusitis (n = 1), and cerebrovascular accident (n = 1). The mean disease-free interval was 29 months (range, 10-78 months). One patient with SCCA recurred in the nasopharynx (overall 2% recurrence rate). He is disease-free 3 years following endoscopic nasopharyngectomy. Three patients with SCCA had endoscopic resection of the skull base, while 1 subject with inverted papilloma pedicled on the superior orbital roof had an osteoplastic flap in conjunction with a Draf III procedure. All others received endoscopic resection. Removal of the bony pedicle resulted in excellent local control of skull base inverted papillomas. Our experience demonstrates that disease eradication with limited morbidity is attainable with this approach. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

Structures of Xishan village landslide in Li County, Sichuan, China, inferred from high-frequency receiver functions of local earthquakes

NASA Astrophysics Data System (ADS)

Wei, Z.; Chu, R.

2017-12-01

Teleseismic receiver function methods are widely used to study the deep structural information beneath the seismic station. However, teleseismic waveforms are difficult to extract the high-frequency receiver function, which are insufficient to constrain the shallow structure because of the inelastic attenuation effect of the earth. In this study, using the local earthquake waveforms collected from 3 broadband stations deployed on the Xishan village landslide in Li County in Sichuan Province, we used the high-frequency receiver function method to study the shallow structure beneath the landslide. We developed the Vp-k (Vp/Vs) staking method of receiver functions, and combined with the H-k stacking and waveform inversion methods of receiver functions to invert the landslide's thickness, S-wave velocity and average Vp/Vs ratio beneath these stations, and compared the thickness with the borehole results. Our results show small-scale lateral variety of velocity structure, a 78-143m/s lower S-wave velocity in the bottom layer and 2.4-3.1 Vp/Vs ratio in the landslide. The observed high Vp/Vs ratio and low S-wave velocity in the bottom layer of the landslide are consistent with low electrical resistivity and water-rich in the bottom layer, suggesting a weak shear strength and potential danger zone in landslide h1. Our study suggest that the local earthquake receiver function can obtain the shallow velocity structural information and supply some seismic constrains for the landslide catastrophe mitigation.

Invertibility of retarded response functions for Laplace transformable potentials: Application to one-body reduced density matrix functional theory.

PubMed

Giesbertz, K J H

2015-08-07

A theorem for the invertibility of arbitrary response functions is presented under the following conditions: the time dependence of the potentials should be Laplace transformable and the initial state should be a ground state, though it might be degenerate. This theorem provides a rigorous foundation for all density-functional-like theories in the time-dependent linear response regime. Especially for time-dependent one-body reduced density matrix (1RDM) functional theory, this is an important step forward, since a solid foundation has currently been lacking. The theorem is equally valid for static response functions in the non-degenerate case, so can be used to characterize the uniqueness of the potential in the ground state version of the corresponding density-functional-like theory. Such a classification of the uniqueness of the non-local potential in ground state 1RDM functional theory has been lacking for decades. With the aid of presented invertibility theorem presented here, a complete classification of the non-uniqueness of the non-local potential in 1RDM functional theory can be given for the first time.

Cosmology and the neutrino mass ordering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hannestad, Steen; Schwetz, Thomas, E-mail: sth@phys.au.dk, E-mail: schwetz@kit.edu

We propose a simple method to quantify a possible exclusion of the inverted neutrino mass ordering from cosmological bounds on the sum of the neutrino masses. The method is based on Bayesian inference and allows for a calculation of the posterior odds of normal versus inverted ordering. We apply the method for a specific set of current data from Planck CMB data and large-scale structure surveys, providing an upper bound on the sum of neutrino masses of 0.14 eV at 95% CL. With this analysis we obtain posterior odds for normal versus inverted ordering of about 2:1. If cosmological datamore » is combined with data from oscillation experiments the odds reduce to about 3:2. For an exclusion of the inverted ordering from cosmology at more than 95% CL, an accuracy of better than 0.02 eV is needed for the sum. We demonstrate that such a value could be reached with planned observations of large scale structure by analysing artificial mock data for a EUCLID-like survey.« less

Cascades of alternating pitchfork and flip bifurcations in H-bridge inverters

NASA Astrophysics Data System (ADS)

Avrutin, Viktor; Zhusubaliyev, Zhanybai T.; Mosekilde, Erik

2017-04-01

Power electronic DC/AC converters (inverters) play an important role in modern power engineering. These systems are also of considerable theoretical interest because their dynamics is influenced by the presence of two vastly different forcing frequencies. As a consequence, inverter systems may be modeled in terms of piecewise smooth maps with an extremely high number of switching manifolds. We have recently shown that models of this type can demonstrate a complicated bifurcation structure associated with the occurrence of border collisions. Considering the example of a PWM H-bridge single-phase inverter, the present paper discusses a number of unusual phenomena that can occur in piecewise smooth maps with a very large number of switching manifolds. We show in particular how smooth (pitchfork and flip) bifurcations may form a macroscopic pattern that stretches across the overall bifurcation structure. We explain the observed bifurcation phenomena, show under which conditions they occur, and describe them quantitatively by means of an analytic approximation.

Structural architecture and tectonic evolution of the Maghara inverted basin, Northern Sinai, Egypt

NASA Astrophysics Data System (ADS)

Moustafa, Adel R.

2014-05-01

Large NE-SW oriented asymmetric inversion anticlines bounded on their southeastern sides by reverse faults affect the exposed Mesozoic and Cenozoic sedimentary rocks of the Maghara area (northern Sinai). Seismic data indicate an earlier Jurassic rifting phase and surface structures indicate Late Cretaceous-Early Tertiary inversion phase. The geometry of the early extensional fault system clearly affected the sense of slip of the inverted faults and the geometry of the inversion anticlines. Rift-parallel fault segments were reactivated by reverse slip whereas rift-oblique fault segments were reactivated as oblique-slip faults or lateral/oblique ramps. New syn-inversion faults include two short conjugate strike-slip sets dissecting the forelimbs of inversion anticlines and the inverted faults as well as a set of transverse normal faults dissecting the backlimbs. Small anticline-syncline fold pairs ornamenting the steep flanks of the inversion anticlines are located at the transfer zones between en echelon segments of the inverted faults.

Improved PEDOT:PSS/c-Si hybrid solar cell using inverted structure and effective passivation

PubMed Central

Zhang, Xisheng; Yang, Dong; Yang, Zhou; Guo, Xiaojia; Liu, Bin; Ren, Xiaodong; Liu, Shengzhong (Frank)

2016-01-01

The PEDOT:PSS is often used as the window layer in the normal structured PEDOT:PSS/c-Si hybrid solar cell (HSC), leading to significantly reduced response, especially in red and near-infrared region. By depositing the PEDOT:PSS on the rear side of the c-Si wafer, we developed an inverted structured HSC with much higher solar cell response in the red and near-infrared spectrum. Passivating the other side with hydrogenated amorphous silicon (a-Si:H) before electrode deposition, the minority carrier lifetime has been significantly increased and the power conversion efficiency (PCE) of the inverted HSC is improved to as high as 16.1% with an open-circuit voltage (Voc) of 634 mV, fill factor (FF) of 70.5%, and short-circuit current density (Jsc) of 36.2 mA cm−2, an improvement of 33% over the control device. The improvements are ascribed to inverted configuration and a-Si:H passivation, which can increase photon carrier generation and reduce carrier recombination, respectively. Both of them will benefit the photovoltaic performance and should be considered as effective design strategies to improve the performance of organic/c-Si HSCs. PMID:27725714

Imaging and engineering the nanoscale-domain structure of a Sr0.61Ba0.39Nb2O6 crystal using a scanning force microscope

NASA Astrophysics Data System (ADS)

Terabe, K.; Takekawa, S.; Nakamura, M.; Kitamura, K.; Higuchi, S.; Gotoh, Y.; Gruverman, A.

2002-09-01

We have investigated the ferroelectric domain structure formed in a Sr0.61Ba0.39Nb2O6 single crystal by cooling the crystal through the Curie point. Imaging the etched surface structure using a scanning force microscope (SFM) in both the topographic mode and the piezoresponse mode revealed that a multidomain structure of nanoscale islandlike domains was formed. The islandlike domains could be inverted by applying an appropriate voltage using a conductive SFM tip. Furthermore, a nanoscale periodically inverted-domain structure was artificially fabricated using the crystal which underwent poling treatment.

Clinical and radiological evaluation of inverse impaction of supernumerary teeth

PubMed Central

Kurklu, Esma; Gencay, Koray; Ak, Gulsum

2013-01-01

Objective: To describe the clinical and radiological features of children with inverted supernumerary teeth. Study Design: Thirty eight patients with inverted supernumerary teeth (ST) were enrolled in this descriptive and restrospective study. Data from patient records including age, gender, status of dentition, number of ST, number of ST in inverted position, coexistence of ST in inverted and normal direction of eruption, location, orientation, morphology, clinical complications, management and radiography were assessed during 3-years period. Results: Thirty eight patients with a mean age of 9.10±1.97 years (range:6-13) and a strong male preponderance of 3.7:1 (male:30, female:8) had a total of 69 ST, of which 41 were in inverted position. Thirty five patients had one (92.1%) inverted tooth, whereas 3 patients had two inverted teeth per case (7.9%). All cases were located in the maxilla. Midline was the most frequent site for the single inverted supernumerary tooth in 18 (47.4%) patients, followed equally by the right and left premaxillary region in 10 patients each (26.3%). Regarding morphology, 30 patients had conical (78.9%) and 8 (21.1%) had incisiform ST. No tuberculate shaped ST was detected. There was no statistically significant difference between number of inverted teeth and delayed tooth eruption, diastema, local malocclusion, palatinal swelling (p>0.05). There was no statistically significant difference between complications and age (p>0.05). Surgical removal at the time of diagnosis with subsequent follow-up during completion of permanent dentition was the treatment approach in all cases. Conclusions: Thorough clinical examination followed by a comprehensive radiographic screening is the crucial determinant of an accurate diagnosis of an impacted ST. Early diagnosis and timely management are key factors to prevent or minimize the complications, which may influence function and esthetics of the teeth and even psychological condition of the growing child. Key words:Supernumerary tooth, impaction, inverted. PMID:23722132

A study of tensile residual strength of composite laminates under different patch-repaired series

NASA Astrophysics Data System (ADS)

Ding, M. H.; zhan, S.; Tang, Y. H.; Wang, L.; Ma, D. Q.; Wang, R. G.

2017-09-01

The tensile behavior of composite laminate structures repaired by bonding external patches was studied in the paper. Two different types of patches including wedge patches and inverted wedge patches were used and failure mechanisms, failure load and strength predictions were studied. A convenient and fast method of building 2-D finite element modeling (FEM) of laminate structure repaired was proposed and the strength of repaired laminate structures was calculated by FEM. The results showed that more than 80% tensile strength of the undamaged laminate could be recovered by bonding patch repairs. Moreover, the results indicated that the strength of inverted wedge patches repair were higher than that of wedge patches repair. FEM simulation results indicated that high stress concentration was found along the edges of invert patches and the most weakness part located in the adhesive bondline. FEM analysis results showed that the strength predicted matched well with the test strength.

Directional radiation of Babinet-inverted optical nanoantenna integrated with plasmonic waveguide

NASA Astrophysics Data System (ADS)

Kim, Jineun; Roh, Young-Geun; Cheon, Sangmo; Jeong Kim, Un; Hwang, Sung Woo; Park, Yeonsang; Lee, Chang-Won

2015-07-01

We present a Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide. Using an integrated nanoantenna, we can couple the plasmon guide mode in a metal-insulator-metal (MIM) structure into the resonant antenna feed directly. The resonantly excited feed slot then radiates to free space and generates a magnetic dipole-like far-field pattern. The coupling efficiency of the integrated nanoantenna is calculated as being approximately 19% using a three-dimensional finite-difference time-domain (3D FDTD) simulation. By adding an auxiliary groove structure along with the feed, the radiation direction can be controlled similar to an optical Yagi-Uda antenna. We also determine, both theoretically and experimentally, that groove depth plays a significant role to function groove structure as a reflector or a director. The demonstrated Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide can be used as a “plasmonic via” in plasmonic nanocircuits.

Directional radiation of Babinet-inverted optical nanoantenna integrated with plasmonic waveguide.

PubMed

Kim, Jineun; Roh, Young-Geun; Cheon, Sangmo; Kim, Un Jeong; Hwang, Sung Woo; Park, Yeonsang; Lee, Chang-Won

2015-07-02

We present a Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide. Using an integrated nanoantenna, we can couple the plasmon guide mode in a metal-insulator-metal (MIM) structure into the resonant antenna feed directly. The resonantly excited feed slot then radiates to free space and generates a magnetic dipole-like far-field pattern. The coupling efficiency of the integrated nanoantenna is calculated as being approximately 19% using a three-dimensional finite-difference time-domain (3D FDTD) simulation. By adding an auxiliary groove structure along with the feed, the radiation direction can be controlled similar to an optical Yagi-Uda antenna. We also determine, both theoretically and experimentally, that groove depth plays a significant role to function groove structure as a reflector or a director. The demonstrated Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide can be used as a "plasmonic via" in plasmonic nanocircuits.

Directional radiation of Babinet-inverted optical nanoantenna integrated with plasmonic waveguide

PubMed Central

Kim, Jineun; Roh, Young-Geun; Cheon, Sangmo; Jeong Kim, Un; Hwang, Sung Woo; Park, Yeonsang; Lee, Chang-Won

2015-01-01

We present a Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide. Using an integrated nanoantenna, we can couple the plasmon guide mode in a metal-insulator-metal (MIM) structure into the resonant antenna feed directly. The resonantly excited feed slot then radiates to free space and generates a magnetic dipole-like far-field pattern. The coupling efficiency of the integrated nanoantenna is calculated as being approximately 19% using a three-dimensional finite-difference time-domain (3D FDTD) simulation. By adding an auxiliary groove structure along with the feed, the radiation direction can be controlled similar to an optical Yagi-Uda antenna. We also determine, both theoretically and experimentally, that groove depth plays a significant role to function groove structure as a reflector or a director. The demonstrated Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide can be used as a “plasmonic via” in plasmonic nanocircuits. PMID:26135115

Design and fabrication of inverted rib waveguide Bragg grating

NASA Astrophysics Data System (ADS)

Huang, Cheng-Sheng; Wang, Wei-Chih

2009-03-01

A polymeric SU8 rib waveguide Bragg grating filterfabricated using reactive ion etching (RIE) and solvent assisted microcontact molding (SAMIM) is presented. SAMIM is one kind of soft lithography. The technique is unique in which that a composite hPDMS/PDMS stamp was used to transfer the grating pattern onto an inverted SU8 rib waveguide system. The composite grating stamp can be used repeatedly several times with degradation. Using this stamp and inverter rib waveguide structure, the Bragg grating filter fabrication can be significantly simplified.

Inversion of parameters for semiarid regions by a neural network

NASA Technical Reports Server (NTRS)

Zurk, Lisa M.; Davis, Daniel; Njoku, Eni G.; Tsang, Leung; Hwang, Jenq-Neng

1992-01-01

Microwave brightness temperatures obtained from a passive radiative transfer model are inverted through use of a neural network. The model is applicable to semiarid regions and produces dual-polarized brightness temperatures for 6.6-, 10.7-, and 37-GHz frequencies. A range of temperatures is generated by varying three geophysical parameters over acceptable ranges: soil moisture, vegetation moisture, and soil temperature. A multilayered perceptron (MLP) neural network is trained with a subset of the generated temperatures, and the remaining temperatures are inverted using a backpropagation method. Several synthetic terrains are devised and inverted by the network under local constraints. All the inversions show good agreement with the original geophysical parameters, falling within 5 percent of the actual value of the parameter range.

Geospeedometry in the inverted metamorphic gradient of the Nestos Thrust Zone in central Rhodope (Northern Greece)

NASA Astrophysics Data System (ADS)

Cioldi, Stefania; Moulas, Evangelos; Burg, Jean-Pierre

2015-04-01

Thrust tectonics and inverted metamorphic gradients are major consequences of large and likely fast movements of crustal segments in compressional environments. The purpose of this study is to investigate the tectonic setting and the timescale of inverted metamorphic zonations related to crustal-scale thrusting. The aim is to contribute understanding the link between mechanical and thermal evolution of major thrust zones and to clarify the nature and the origin of orogenic heat. The Rhodope metamorphic complex (Northern Greece) is interpreted as a part of the Alpine-Himalaya orogenic belt and represents a collisional system with an association of both large-scale thrusting and pervasive exhumation tectonics. The Nestos Shear Zone overprints the suture boundary with a NNE-dipping pile of schists displaying inverted isograds. The inverted metamorphic zones start from chlorite-muscovite grade at the bottom and reach kyanite-sillimanite grades with migmatites in the upper structural levels. In order to reconstruct the thermo-tectonic evolution of inverted metamorphic zonation, reliable geochronological data are essential. 40Ar/39Ar geochronology with step-heating technique on white mica from micaschists provided a temporal resolution with the potential to characterize shearing. 40Ar/39Ar dating across the Nestos Shear Zone yields Late Eocene-Early Oligocene (40-30 Ma) cooling (~400-350° C) ages, which correspond to local thermo-deformation episodes linked to late and post-orogenic intrusions. U-Pb Sensitive High Resolution Ion Microprobe (SHRIMP) zircon geochronology on leucosomes from migmatitic orthogneisses were considered to estimate the age of peak metamorphic conditions, contemporaneous with anatexis. U-Pb ages of zircon rims specify regional partial melting during the Early Cretaceous (160-120 Ma). This is in disagreement with previous assertions, which argued that the formation of leucosomes in this region is Late Eocene (42-35 Ma) and implied multiple subductions and multiple metamorphic cycles during orogeny. Garnet geospeedometry considers the kinetic response of minerals and allowed estimating the absolute time-dependent thermal evolution by diffusive element profiles in garnet. Inverse-fitting numerical model considering Fractionation and Diffusion in GarnEt (FRIDGE) calculates garnet composition profiles by introducing P-T-t paths and bulk-rock composition of a specific sample. Preliminary results of Fe-Mg - Ca - Mn garnet fractionation-diffusion modelling indicate very short timescale (between 2 and 5 Ma) for peak metamorphic conditions in the Rhodope collisional system.

Seismic structure beneath Mt Vesuvius from receiver function analysis and local earthquakes tomography: evidences for location and geometry of the magma chamber

NASA Astrophysics Data System (ADS)

Agostinetti, N. Piana; Chiarabba, C.

2008-12-01

The recognition and localization of magmatic fluids are pre-requisites for evaluating the volcano hazard of the highly urbanized area of Mt Vesuvius. Here we show evidence and constraints for the volumetric estimation of magmatic fluids underneath this sleeping volcano. We use Receiver Functions for teleseismic data recorded at a temporary broad-band station installed on the volcano to constrain the S-wave velocity structure in the crust. Receiver Functions are analysed and inverted using the Neighbourhood Algorithm approach. The 1-D S-velocity profile is jointly interpreted and discussed with a new Vp and Vp/Vs image obtained by applying double difference tomographic techniques to local earthquakes. Seismologic data define the geometry of an axial, cylindrical high Vp, high Vs body consisting of a shallow solidified materials, probably the remnants of the caldera, and ultramafic rocks paving the crustal magma chamber. Between these two anomalies, we find a small region where the shear wave velocity drops, revealing the presence of magma at relatively shallow depths. The volume of fluids (30 km3) is sufficient to contribute future explosive eruptions.

Properties of ion temperature gradient and trapped electron modes in tokamak plasmas with inverted density profiles

NASA Astrophysics Data System (ADS)

Du, Huarong; Jhang, Hogun; Hahm, T. S.; Dong, J. Q.; Wang, Z. X.

2017-12-01

We perform a numerical study of linear stability of the ion temperature gradient (ITG) mode and the trapped electron mode (TEM) in tokamak plasmas with inverted density profiles. A local gyrokinetic integral equation is applied for this study. From comprehensive parametric scans, we obtain stability diagrams for ITG modes and TEMs in terms of density and temperature gradient scale lengths. The results show that, for the inverted density profile, there exists a normalized threshold temperature gradient above which the ITG mode and the TEM are either separately or simultaneously unstable. The instability threshold of the TEM for the inverted density profile is substantially different from that for normal and flat density profiles. In addition, deviations are found on the ITG threshold from an early analytic theory in sheared slab geometry with the adiabatic electron response [T. S. Hahm and W. M. Tang, Phys. Fluids B 1, 1185 (1989)]. A possible implication of this work on particle transport in pellet fueled tokamak plasmas is discussed.

Photovoltaics for the Defense Community through Manufacturing Advances

DTIC Science & Technology

2009-04-27

the mod- ule, the inverter, and the balance of system (BOS) costs. The module is the “solar panel ” component that generates electricity, the inverter...Silicon Key areas Examples Ingot Crystal Structures • Multicrystalline • Monocrystalline Wafering Techniques • Wire sawing • Pulling slices off the ingot

Research of frequency converters energy characteristics of drilling rigs

NASA Astrophysics Data System (ADS)

Vasiliev, B. Y.; Kalashnikov, O. V.; Oleynikova, A. M.; Ivanovsky, A. I.; Grudinin, N. N.

2017-10-01

The investigation deals with multi-motor electric drives with frequency converters of various structures: with a common converter, with an individual converter, with a multi-inverter frequency converter. Their shortcomings and advantages were analyzed and there were drawn conclusions about the expediency of using each structure. Expediency of using multi-inverter frequency converters with an active frond end was shown to ensure the highest power characteristics of multi-motor electric drives of drilling rigs’ main mechanisms.

Global Admittance Estimates of Elastic and Crustal Thickness of Venus: Results from Top, Hot Spot, and Bottom Loading Models

NASA Technical Reports Server (NTRS)

Smrekar, S. E.; Anderson, F. S.

2005-01-01

We have calculated admittance spectra using the spatio-spectral method [14] for Venus by moving the central location of the spectrum over a 1 grid, create 360x180 admittance spectra. We invert the observed admittance using top-loading (TL), hot spot (HS), and bottom loading (BL) models, resulting in elastic, crustal, and lithospheric thickness estimates (Te, Zc, and Zl) [0]. The result is a global map for interpreting subsurface structure. Estimated values of Te and Zc concur with previous TL local admittance results, but BL estimates indicate larger values than previously suspected.

Efficient transformer for electromagnetic waves

DOEpatents

Miller, R.B.

A transformer structure for efficient transfer of electromagnetic energy from a transmission line to an unmatched load provides voltage multiplication and current division by a predetermined constant. Impedance levels are transformed by the square of that constant. The structure includes a wave splitter, connected to an input transmission device and to a plurality of output transmission devices. The output transmission devices are effectively connected in parallel to the input transmission device. The output transmission devices are effectively series connected to provide energy to a load. The transformer structure is particularly effective in increasing efficiency of energy transfer through an inverting convolute structure by capturing and transferring energy losses from the inverter to the load.

Face Context Influences Local Part Processing: An ERP Study.

PubMed

Zhang, Hong; Sun, Yaoru; Zhao, Lun

2017-09-01

Perception of face parts on the basis of features is thought to be different from perception of whole faces, which is more based on configural information. Face context is also suggested to play an important role in face processing. To investigate how face context influences the early-stage perception of facial local parts, we used an oddball paradigm that tested perceptual stages of face processing rather than recognition. We recorded the event-related potentials (ERPs) elicited by whole faces and face parts presented in four conditions (upright-normal, upright-thatcherised, inverted-normal and inverted-thatcherised), as well as the ERPs elicited by non-face objects (whole houses and house parts) with corresponding conditions. The results showed that face context significantly affected the N170 with increased amplitudes and earlier peak latency for upright normal faces. Removing face context delayed the P1 latency but did not affect the P1 amplitude prominently for both upright and inverted normal faces. Across all conditions, neither the N170 nor the P1 was modulated by house context. The significant changes on the N170 and P1 components revealed that face context influences local part processing at the early stage of face processing and this context effect might be specific for face perception. We further suggested that perceptions of whole faces and face parts are functionally distinguished.

Can natural proteins designed with 'inverted' peptide sequences adopt native-like protein folds?

PubMed

Sridhar, Settu; Guruprasad, Kunchur

2014-01-01

We have carried out a systematic computational analysis on a representative dataset of proteins of known three-dimensional structure, in order to evaluate whether it would possible to 'swap' certain short peptide sequences in naturally occurring proteins with their corresponding 'inverted' peptides and generate 'artificial' proteins that are predicted to retain native-like protein fold. The analysis of 3,967 representative proteins from the Protein Data Bank revealed 102,677 unique identical inverted peptide sequence pairs that vary in sequence length between 5-12 and 18 amino acid residues. Our analysis illustrates with examples that such 'artificial' proteins may be generated by identifying peptides with 'similar structural environment' and by using comparative protein modeling and validation studies. Our analysis suggests that natural proteins may be tolerant to accommodating such peptides.

[Ultrastructural organization of cytoplasmatic membrane of Anaerobacter polyendosporus studied by electron microscopic cryofractography].

PubMed

Duda, V I; Suzina, N E; Dmitriev, V V

2001-01-01

Anaerobacter polyendosporus cells do not have typical mesosomes. However, the analysis of this anaerobic multispore bacterium by electron microscopic cryofractography showed that its cytoplasmic membrane contains specific intramembrane structures in the form of flat lamellar inverted lipid membranes tenths of nanometers to several microns in size. It was found that these structures are located in the hydrophobic interior between the outer and inner leaflets of the cytoplasmic membrane and do not contain intramembrane particles that are commonly present on freeze-fracture replicas. The flat inverted lipid membranes were revealed in bacterial cells cultivated under normal growth conditions, indicating the existence of a complex-type compartmentalization in biological membranes, which manifests itself in the formation of intramembrane compartments having the appearance of vesicles and inverted lipid membranes.

Anisotropic Babinet-Invertible Metasurfaces to Realize Transmission-Reflection Switching for Orthogonal Polarizations of Light

NASA Astrophysics Data System (ADS)

Nakata, Yosuke; Urade, Yoshiro; Okimura, Kunio; Nakanishi, Toshihiro; Miyamaru, Fumiaki; Takeda, Mitsuo Wada; Kitano, Masao

2016-10-01

The electromagnetic properties of an extremely thin metallic checkerboard drastically change from resonant reflection (transmission) to resonant transmission (reflection) when the local electrical conductivity at the interconnection points of the checkerboard is switched. To date, such critical transitions of metasurfaces have been applied only when they have fourfold rotational symmetry, and their application to polarization control, which requires anisotropy, has been unexplored. To overcome this applicability limitation and open up alternative pathways for dynamic deep-subwavelength polarization control by utilizing critical transitions of checkerboardlike metasurfaces, we introduce a universal class of anisotropic Babinet-invertible metasurfaces enabling transmission-reflection switching for each orthogonally polarized wave. As an application of anisotropic Babinet-invertible metasurfaces, we experimentally realize a reconfigurable terahertz polarizer whose transmitting axis can be dynamically rotated by 90°.

Clinical and radiological evaluation of inverse impaction of supernumerary teeth.

PubMed

Tuna, Elif-Bahar; Kurklu, Esma; Gencay, Koray; Ak, Gulsum

2013-07-01

To describe the clinical and radiological features of children with inverted supernumerary teeth. Thirty eight patients with inverted supernumerary teeth (ST) were enrolled in this descriptive and restrospective study. Data from patient records including age, gender, status of dentition, number of ST, number of ST in inverted position, coexistence of ST in inverted and normal direction of eruption, location, orientation, morphology, clinical complications, management and radiography were assessed during 3-years period. Thirty eight patients with a mean age of 9.10 ± 1.97 years (range:6-13) and a strong male preponderance of 3.7:1 (male:30, female:8) had a total of 69 ST, of which 41 were in inverted position. Thirty five patients had one (92.1%) inverted tooth, whereas 3 patients had two inverted teeth per case (7.9%). All cases were located in the maxilla. Midline was the most frequent site for the single inverted supernumerary tooth in 18 (47.4%) patients, followed equally by the right and left premaxillary region in 10 patients each (26.3%). Regarding morphology, 30 patients had conical (78.9%) and 8 (21.1%) had incisiform ST. No tuberculate shaped ST was detected. There was no statistically significant difference between number of inverted teeth and delayed tooth eruption, diastema, local malocclusion, palatinal swelling (p>0.05). There was no statistically significant difference between complications and age (p>0.05). Surgical removal at the time of diagnosis with subsequent follow-up during completion of permanent dentition was the treatment approach in all cases. Thorough clinical examination followed by a comprehensive radiographic screening is the crucial determinant of an accurate diagnosis of an impacted ST. Early diagnosis and timely management are key factors to prevent or minimize the complications, which may influence function and esthetics of the teeth and even psychological condition of the growing child.

Craton Heterogeneity in the South American Lithosphere

NASA Astrophysics Data System (ADS)

Lloyd, S.; Van der Lee, S.; Assumpcao, M.; Feng, M.; Franca, G. S.

2012-04-01

We investigate structure of the lithosphere beneath South America using receiver functions, surface wave dispersion analysis, and seismic tomography. The data used include recordings from 20 temporary broadband seismic stations deployed across eastern Brazil (BLSP02) and from the Chile Ridge Subduction Project seismic array in southern Chile (CRSP). By jointly inverting Moho point constraints, Rayleigh wave group velocities, and regional S and Rayleigh wave forms we obtain a continuous map of Moho depth. The new tomographic Moho map suggests that Moho depth and Moho relief vary slightly with age within the Precambrian crust. Whether or not a correlation between crustal thickness and geologic age can be derived from the pre-interpolation point constraints depends strongly on the selected subset of receiver functions. This implies that using only pre-interpolation point constraints (receiver functions) inadequately samples the spatial variation in geologic age. We also invert for S velocity structure and estimate the depth of the lithosphere-asthenosphere boundary (LAB) in Precambrian South America. The new model reveals a relatively thin lithosphere throughout most of Precambrian South America (< 140 km). Comparing LAB depth with lithospheric age shows they are overall positively correlated, whereby the thickest lithosphere occurs in the relatively small Saõ Francisco craton (200 km). However, within the larger Amazonian craton the younger lithosphere is thicker, indicating that locally even larger cratons are not protected from erosion or reworking of the lithosphere.

Inverted formin 2 in focal adhesions promotes dorsal stress fiber and fibrillar adhesion formation to drive extracellular matrix assembly

PubMed Central

Skau, Colleen T.; Plotnikov, Sergey V.; Doyle, Andrew D.; Waterman, Clare M.

2015-01-01

Actin filaments and integrin-based focal adhesions (FAs) form integrated systems that mediate dynamic cell interactions with their environment or other cells during migration, the immune response, and tissue morphogenesis. How adhesion-associated actin structures obtain their functional specificity is unclear. Here we show that the formin-family actin nucleator, inverted formin 2 (INF2), localizes specifically to FAs and dorsal stress fibers (SFs) in fibroblasts. High-resolution fluorescence microscopy and manipulation of INF2 levels in cells indicate that INF2 plays a critical role at the SF–FA junction by promoting actin polymerization via free barbed end generation and centripetal elongation of an FA-associated actin bundle to form dorsal SF. INF2 assembles into FAs during maturation rather than during their initial generation, and once there, acts to promote rapid FA elongation and maturation into tensin-containing fibrillar FAs in the cell center. We show that INF2 is required for fibroblasts to organize fibronectin into matrix fibers and ultimately 3D matrices. Collectively our results indicate an important role for the formin INF2 in specifying the function of fibrillar FAs through its ability to generate dorsal SFs. Thus, dorsal SFs and fibrillar FAs form a specific class of integrated adhesion-associated actin structure in fibroblasts that mediates generation and remodeling of ECM. PMID:25918420

Developments in a methodology for the design of engineered invert traps in combined sewer systems.

PubMed

Buxton, A; Tait, S; Stovin, V; Saul, A

2002-01-01

Sediments within sewers can have a significant effect on the operation of the sewer system and on the surrounding natural and urban environment. One possible method for the management of sewer sediments is the use of slotted invert traps. Although invert traps can be used to selectively trap only inorganic bedload material, little is known with regard to the design of these structures. This paper presents results from a laboratory investigation comparing the trapping performance of three slot size configurations of a laboratory-scale invert trap. The paper also presents comparative results from a two-dimensional computational model utilising stochastic particle tracking. This investigation shows that particle tracking consistently over-predicts sediment retention efficiencies observed within the laboratory model.

Helical quantum states in HgTe quantum dots with inverted band structures.

PubMed

Chang, Kai; Lou, Wen-Kai

2011-05-20

We investigate theoretically the electron states in HgTe quantum dots (QDs) with inverted band structures. In sharp contrast to conventional semiconductor quantum dots, the quantum states in the gap of the HgTe QD are fully spin-polarized and show ringlike density distributions near the boundary of the QD and spin-angular momentum locking. The persistent charge currents and magnetic moments, i.e., the Aharonov-Bohm effect, can be observed in such a QD structure. This feature offers us a practical way to detect these exotic ringlike edge states by using the SQUID technique.

The inverted Batman incision: a new incision in transcolumellar incision for open rhinoplasty.

PubMed

Nakanishi, Yuji; Nagasao, Tomohisa; Shimizu, Yusuke; Miyamoto, Junpei; Fukuta, Keizo; Kishi, Kazuo

2013-12-01

Columellar and nostril shapes often present irregularity after transcolumellar incision for open rhinoplasty, because of the contracture of the incised wound. The present study introduces a new technique to prevent this complication, and verifies its efficacy in improving cosmetic appearance. In our new method, a zig-zag incision with three small triangular flaps is made on the columella and in the pericolumellar regions of the bilateral nostril rims. Since the shape of the incision resembles the contour of an inverted "batman", we term our new method the "Inverted Batman" incision. To verify the effectiveness of the Inverted Batman incision, aesthetic evaluation was conducted for 21 patients operated on using the conventional transcolumellar incision (Conventional Group) and 19 patients operated on using the Inverted Batman incision (Inverted Batman Group). The evaluation was performed by three plastic surgeons, using a four-grade scale to assess three separate items: symmetry of bilateral soft triangles, symmetry of bilateral margins of the columella, and evenness of the columellar surface. The scores of the two groups for these three items were compared using a non-parametric test (Mann-Whitney U-test). With all three items, the Inverted Batman group patients present higher scores than Conventional Group patients. The Inverted Batman incision is effective in preserving the correct anatomical structure of the columella, soft triangle, and nostril rims. Hence, we recommend the Inverted Batman incision as a useful technique for open rhinoplasty.

Suppression of Lateral Diffusion and Surface Leakage Currents in nBn Photodetectors Using an Inverted Design

NASA Astrophysics Data System (ADS)

Du, X.; Savich, G. R.; Marozas, B. T.; Wicks, G. W.

2018-02-01

Surface leakage and lateral diffusion currents in InAs-based nBn photodetectors have been investigated. Devices fabricated using a shallow etch processing scheme that etches through the top contact and stops at the barrier exhibited large lateral diffusion current but undetectably low surface leakage. Such large lateral diffusion current significantly increased the dark current, especially in small devices, and causes pixel-to-pixel crosstalk in detector arrays. To eliminate the lateral diffusion current, two different approaches were examined. The conventional solution utilized a deep etch process, which etches through the top contact, barrier, and absorber. This deep etch processing scheme eliminated lateral diffusion, but introduced high surface current along the device mesa sidewalls, increasing the dark current. High device failure rate was also observed in deep-etched nBn structures. An alternative approach to limit lateral diffusion used an inverted nBn structure that has its absorber grown above the barrier. Like the shallow etch process on conventional nBn structures, the inverted nBn devices were fabricated with a processing scheme that only etches the top layer (the absorber, in this case) but avoids etching through the barrier. The results show that inverted nBn devices have the advantage of eliminating the lateral diffusion current without introducing elevated surface current.

Recent Advances in the Inverted Planar Structure of Perovskite Solar Cells.

PubMed

Meng, Lei; You, Jingbi; Guo, Tzung-Fang; Yang, Yang

2016-01-19

Inorganic-organic hybrid perovskite solar cells research could be traced back to 2009, and initially showed 3.8% efficiency. After 6 years of efforts, the efficiency has been pushed to 20.1%. The pace of development was much faster than that of any type of solar cell technology. In addition to high efficiency, the device fabrication is a low-cost solution process. Due to these advantages, a large number of scientists have been immersed into this promising area. In the past 6 years, much of the research on perovskite solar cells has been focused on planar and mesoporous device structures employing an n-type TiO2 layer as the bottom electron transport layer. These architectures have achieved champion device efficiencies. However, they still possess unwanted features. Mesoporous structures require a high temperature (>450 °C) sintering process for the TiO2 scaffold, which will increase the cost and also not be compatible with flexible substrates. While the planar structures based on TiO2 (regular structure) usually suffer from a large degree of J-V hysteresis. Recently, another emerging structure, referred to as an "inverted" planar device structure (i.e., p-i-n), uses p-type and n-type materials as bottom and top charge transport layers, respectively. This structure derived from organic solar cells, and the charge transport layers used in organic photovoltaics were successfully transferred into perovskite solar cells. The p-i-n structure of perovskite solar cells has shown efficiencies as high as 18%, lower temperature processing, flexibility, and, furthermore, negligible J-V hysteresis effects. In this Account, we will provide a comprehensive comparison of the mesoporous and planar structures, and also the regular and inverted of planar structures. Later, we will focus the discussion on the development of the inverted planar structure of perovskite solar cells, including film growth, band alignment, stability, and hysteresis. In the film growth part, several methods for obtaining high quality perovskite films are reviewed. In the interface engineering parts, the effect of hole transport layer on subsequent perovskite film growth and their interface band alignment, and also the effect of electron transport layers on charge transport and interface contact will be discussed. As concerns stability, the role of charge transport layers especially the top electron transport layer in the devices stability will be concluded. In the hysteresis part, possible reasons for hysteresis free in inverted planar structure are provided. At the end of this Account, future development and possible solutions to the remaining challenges facing the commercialization of perovskite solar cells are discussed.

Perovskite-based solar cells with inorganic inverted hybrid planar heterojunction structure

NASA Astrophysics Data System (ADS)

Lai, Wei-Chih; Lin, Kun-Wei; Guo, Tzung-Fang; Chen, Peter; Liao, Yuan-Yu

2018-01-01

We demonstrated the good performance of inorganic inverted CH3NH3PbI3 perovskite-based solar cells (SCs) with glass/ITO/NiOx/CH3NH3PbI3 perovskite/C60/ room temperature (RT)-sputtered ZnO/Al structure. We adopted spin coating and RT sputtering for the deposition of NiOx and ZnO, respectively. The inorganic hole and electron transport layer of NiOx and RT-sputtered ZnO, respectively, could improve the open-circuit voltage (VOC), short-circuit current density (JSC), and power conversion efficiency (η%) of the SCs. We obtained inorganic inverted CH3NH3PbI3 perovskite-based SCs with a JSC of 21.96 A/cm2, a VOC of 1.02 V, a fill factor (FF%) of 68.2%, and an η% of 15.3% despite the sputtering damage of the RT-sputtered ZnO deposition. Moreover, the RT-sputtered ZnO could function as a diffusion barrier for Al, moisture, and O2. The inorganic inverted CH3NH3PbI3 perovskite-based SCs demonstrated improved storage reliability.

Zak phase and band inversion in dimerized one-dimensional locally resonant metamaterials

NASA Astrophysics Data System (ADS)

Zhu, Weiwei; Ding, Ya-qiong; Ren, Jie; Sun, Yong; Li, Yunhui; Jiang, Haitao; Chen, Hong

2018-05-01

The Zak phase, which refers to Berry's phase picked up by a particle moving across the Brillouin zone, characterizes the topological properties of Bloch bands in a one-dimensional periodic system. Here the Zak phase in dimerized one-dimensional locally resonant metamaterials is investigated. It is found that there are some singular points in the bulk band across which the Bloch states contribute π to the Zak phase, whereas in the rest of the band the contribution is nearly zero. These singular points associated with zero reflection are caused by two different mechanisms: the dimerization-independent antiresonance of each branch and the dimerization-dependent destructive interference in multiple backscattering. The structure undergoes a topological phase-transition point in the band structure where the band inverts, and the Zak phase, which is determined by the numbers of singular points in the bulk band, changes following a shift in dimerization parameter. Finally, the interface state between two dimerized metamaterial structures with different topological properties in the first band gap is demonstrated experimentally. The quasi-one-dimensional configuration of the system allows one to explore topology-inspired new methods and applications on the subwavelength scale.

Patching the Exchange-Correlation Potential in Density Functional Theory.

PubMed

Huang, Chen

2016-05-10

A method for directly patching exchange-correlation (XC) potentials in materials is derived. The electron density of a system is partitioned into subsystem densities by dividing its Kohn-Sham (KS) potential among the subsystems. Inside each subsystem, its projected KS potential is required to become the total system's KS potential. This requirement, together with the nearsightedness principle of electronic matters, ensures that the electronic structures inside subsystems can be good approximations to the total system's electronic structure. The nearsightedness principle also ensures that subsystem densities could be well localized in their regions, making it possible to use high-level methods to invert the XC potentials for subsystem densities. Two XC patching methods are developed. In the local XC patching method, the total system's XC potential is improved in the cluster region. We show that the coupling between a cluster and its environment is important for achieving a fast convergence of the electronic structure in the cluster region. In the global XC patching method, we discuss how to patch the subsystem XC potentials to construct the XC potential in the total system, aiming to scale up high-level quantum mechanics simulations of materials. Proof-of-principle examples are given.

Solution processable inverted structure ZnO-organic hybrid heterojuction white LEDs

NASA Astrophysics Data System (ADS)

Bano, N.; Hussain, I.; Soomro, M. Y.; EL-Naggar, A. M.; Albassam, A. A.

2018-05-01

Improving luminance efficiency and colour purity are the most important challenges for zinc oxide (ZnO)-organic hybrid heterojunction light emitting diodes (LEDs), affecting their large area applications. If ZnO-organic hybrid heterojunction white LEDs are fabricated by a hydrothermal method, it is difficult to obtain pure and stable blue emission from PFO due to the presence of an undesirable green emission. In this paper, we present an inverted-structure ZnO-organic hybrid heterojunction LED to avoid green emission from PFO, which mainly originates during device processing. With this configuration, each ZnO nanorod (NR) forms a discrete p-n junction; therefore, large-area white LEDs can be designed without compromising the junction area. The configuration used for this novel structure is glass/ZnO NRs/PFO/PEDOT:PSS/L-ITO, which enables the development of efficient, large-area and low-cost hybrid heterojunction LEDs. Inverted-structure ZnO-organic hybrid heterojunction white LEDs offer several improvements in terms of brightness, size, colour, external quantum efficiency and a wider applicability as compared to normal architecture LEDs.

High efficiency H6 single-phase transformerless grid-tied PV inverter with proposed modulation for reactive power generation

NASA Astrophysics Data System (ADS)

Almasoudi, Fahad M.; Alatawi, Khaled S.; Matin, Mohammad

2017-08-01

Implementation of transformerless inverters in PV grid-tied system offer great benefits such as high efficiency, light weight, low cost, etc. Most of the proposed transformerless inverters in literature are verified for only real power application. Currently, international standards such as VDE-AR-N 4105 has demanded that PV grid-tied inverters should have the ability of controlling a specific amount of reactive power. Generation of reactive power cannot be accomplished in single phase transformerless inverter topologies because the existing modulation techniques are not adopted for a freewheeling path in the negative power region. This paper enhances a previous high efficiency proposed H6 trnasformerless inverter with SiC MOSFETs and demonstrates new operating modes for the generation of reactive power. A proposed pulse width modulation (PWM) technique is applied to achieve bidirectional current flow through freewheeling state. A comparison of the proposed H6 transformerless inverter using SiC MOSFETs and Si MOSFTEs is presented in terms of power losses and efficiency. The results show that reactive power control is attained without adding any additional active devices or modification to the inverter structure. Also, the proposed modulation maintains a constant common mode voltage (CM) during every operating mode and has low leakage current. The performance of the proposed system verifies its effectiveness in the next generation PV system.

Origin-Dependent Inverted-Repeat Amplification: Tests of a Model for Inverted DNA Amplification

PubMed Central

Brewer, Bonita J.; Payen, Celia; Di Rienzi, Sara C.; Higgins, Megan M.; Ong, Giang; Dunham, Maitreya J.; Raghuraman, M. K.

2015-01-01

DNA replication errors are a major driver of evolution—from single nucleotide polymorphisms to large-scale copy number variations (CNVs). Here we test a specific replication-based model to explain the generation of interstitial, inverted triplications. While no genetic information is lost, the novel inversion junctions and increased copy number of the included sequences create the potential for adaptive phenotypes. The model—Origin-Dependent Inverted-Repeat Amplification (ODIRA)—proposes that a replication error at pre-existing short, interrupted, inverted repeats in genomic sequences generates an extrachromosomal, inverted dimeric, autonomously replicating intermediate; subsequent genomic integration of the dimer yields this class of CNV without loss of distal chromosomal sequences. We used a combination of in vitro and in vivo approaches to test the feasibility of the proposed replication error and its downstream consequences on chromosome structure in the yeast Saccharomyces cerevisiae. We show that the proposed replication error—the ligation of leading and lagging nascent strands to create “closed” forks—can occur in vitro at short, interrupted inverted repeats. The removal of molecules with two closed forks results in a hairpin-capped linear duplex that we show replicates in vivo to create an inverted, dimeric plasmid that subsequently integrates into the genome by homologous recombination, creating an inverted triplication. While other models have been proposed to explain inverted triplications and their derivatives, our model can also explain the generation of human, de novo, inverted amplicons that have a 2:1 mixture of sequences from both homologues of a single parent—a feature readily explained by a plasmid intermediate that arises from one homologue and integrates into the other homologue prior to meiosis. Our tests of key features of ODIRA lend support to this mechanism and suggest further avenues of enquiry to unravel the origins of interstitial, inverted CNVs pivotal in human health and evolution. PMID:26700858

Origin-Dependent Inverted-Repeat Amplification: Tests of a Model for Inverted DNA Amplification.

PubMed

Brewer, Bonita J; Payen, Celia; Di Rienzi, Sara C; Higgins, Megan M; Ong, Giang; Dunham, Maitreya J; Raghuraman, M K

2015-12-01

DNA replication errors are a major driver of evolution--from single nucleotide polymorphisms to large-scale copy number variations (CNVs). Here we test a specific replication-based model to explain the generation of interstitial, inverted triplications. While no genetic information is lost, the novel inversion junctions and increased copy number of the included sequences create the potential for adaptive phenotypes. The model--Origin-Dependent Inverted-Repeat Amplification (ODIRA)-proposes that a replication error at pre-existing short, interrupted, inverted repeats in genomic sequences generates an extrachromosomal, inverted dimeric, autonomously replicating intermediate; subsequent genomic integration of the dimer yields this class of CNV without loss of distal chromosomal sequences. We used a combination of in vitro and in vivo approaches to test the feasibility of the proposed replication error and its downstream consequences on chromosome structure in the yeast Saccharomyces cerevisiae. We show that the proposed replication error-the ligation of leading and lagging nascent strands to create "closed" forks-can occur in vitro at short, interrupted inverted repeats. The removal of molecules with two closed forks results in a hairpin-capped linear duplex that we show replicates in vivo to create an inverted, dimeric plasmid that subsequently integrates into the genome by homologous recombination, creating an inverted triplication. While other models have been proposed to explain inverted triplications and their derivatives, our model can also explain the generation of human, de novo, inverted amplicons that have a 2:1 mixture of sequences from both homologues of a single parent--a feature readily explained by a plasmid intermediate that arises from one homologue and integrates into the other homologue prior to meiosis. Our tests of key features of ODIRA lend support to this mechanism and suggest further avenues of enquiry to unravel the origins of interstitial, inverted CNVs pivotal in human health and evolution.

Highly Efficient and Fully Solution-Processed Inverted Light-Emitting Diodes with Charge Control Interlayers.

PubMed

Fu, Yan; Jiang, Wei; Kim, Daekyoung; Lee, Woosuk; Chae, Heeyeop

2018-05-23

In this work, we developed a charge control sandwich structure around QD layers for the inverted QLEDs, the performance of which is shown to exceed that of the conventional QLEDs in terms of the external quantum efficiency (EQE) and the current efficiency (CE). The QD light-emitting layer (EML) is sandwiched with two ultrathin interfacial layers: one is a poly(9-vinlycarbazole) (PVK) layer to prevent excess electrons, and the other is a polyethylenimine ethoxylated (PEIE) layer to reduce the hole injection barrier. The sandwich structure resolves the imbalance between injected holes and electrons and brings the level of balanced charge carriers to a maximum. We demonstrated the highly improved performance of 89.8 cd/A of current efficiency, 22.4% of external quantum efficiency, and 72 814 cd m -2 of maximum brightness with the solution-processed inverted QLED. This sandwich structure (PVK/QD/PEIE), as a framework, can be applied to various QLED devices for enhancing performance.

Landscape Encodings Enhance Optimization

PubMed Central

Klemm, Konstantin; Mehta, Anita; Stadler, Peter F.

2012-01-01

Hard combinatorial optimization problems deal with the search for the minimum cost solutions (ground states) of discrete systems under strong constraints. A transformation of state variables may enhance computational tractability. It has been argued that these state encodings are to be chosen invertible to retain the original size of the state space. Here we show how redundant non-invertible encodings enhance optimization by enriching the density of low-energy states. In addition, smooth landscapes may be established on encoded state spaces to guide local search dynamics towards the ground state. PMID:22496860

Three dimensional-stacked complementary thin-film transistors using n-type Al:ZnO and p-type NiO thin-film transistors.

PubMed

Lee, Ching-Ting; Chen, Chia-Chi; Lee, Hsin-Ying

2018-03-05

The three dimensional inverters were fabricated using novel complementary structure of stacked bottom n-type aluminum-doped zinc oxide (Al:ZnO) thin-film transistor and top p-type nickel oxide (NiO) thin-film transistor. When the inverter operated at the direct voltage (V DD ) of 10 V and the input voltage from 0 V to 10 V, the obtained high performances included the output swing of 9.9 V, the high noise margin of 2.7 V, and the low noise margin of 2.2 V. Furthermore, the high performances of unskenwed inverter were demonstrated by using the novel complementary structure of the stacked n-type Al:ZnO thin-film transistor and p-type nickel oxide (NiO) thin-film transistor.

Shallow magma diversions during explosive maar-diatreme eruptions in mafic volcanic fields

NASA Astrophysics Data System (ADS)

Le Corvec, N.; Muirhead, J.; White, J. D. L.

2017-12-01

Maar-diatremes are inverted conical structures formed by subterranean excavation and remobilization of country rocks during explosive volcanism and common in mafic volcanic fields. We focus on impacts of excavation and filling of maar-diatremes on the local state of stress, and its subsequent influence on underlying feeder dikes, which are critical for understanding the development of intrusive networks that feed surface eruptions. We address this issue using finite element models in COMSOL Multiphysics®. Inverted conical structures of varying sizes are excavated in a gravitationally loaded elastic half-space, and then progressively filled with volcaniclastic material, resulting in changes in the orientations and magnitudes of stresses generated within surrounding rocks and within the filling portion of the maar-diatreme. Our results show that rapid unloading during maar-diatreme excavation generates a horizontal compressive stress state beneath diatremes. These stresses allow magma to divert laterally as saucer-shaped sills and circumferential dikes at varying depths in the shallow feeder system, and produce intrusion geometries consistent with both field observations from exhumed volcanic fields and conceptual models of diatreme growth. Stresses generated in these models also provide an explanation for the evolving locations of fragmentation zones over the course of diatreme's filling. In particular, results from this study suggest that: (1) extensional stresses at the base of the diatreme fill favor magma ascent in the lower half of the structure, and possibly promote volatile exsolution and magma fragmentation; and (2) increased filling of diatremes creates a shallow compressive stress state that can inhibit magma ascent to the surface, promoting widespread intra-diatreme explosions, efficient mixing of host rock, and upward widening of the diatreme structure.

detectIR: a novel program for detecting perfect and imperfect inverted repeats using complex numbers and vector calculation.

PubMed

Ye, Congting; Ji, Guoli; Li, Lei; Liang, Chun

2014-01-01

Inverted repeats are present in abundance in both prokaryotic and eukaryotic genomes and can form DNA secondary structures--hairpins and cruciforms that are involved in many important biological processes. Bioinformatics tools for efficient and accurate detection of inverted repeats are desirable, because existing tools are often less accurate and time consuming, sometimes incapable of dealing with genome-scale input data. Here, we present a MATLAB-based program called detectIR for the perfect and imperfect inverted repeat detection that utilizes complex numbers and vector calculation and allows genome-scale data inputs. A novel algorithm is adopted in detectIR to convert the conventional sequence string comparison in inverted repeat detection into vector calculation of complex numbers, allowing non-complementary pairs (mismatches) in the pairing stem and a non-palindromic spacer (loop or gaps) in the middle of inverted repeats. Compared with existing popular tools, our program performs with significantly higher accuracy and efficiency. Using genome sequence data from HIV-1, Arabidopsis thaliana, Homo sapiens and Zea mays for comparison, detectIR can find lots of inverted repeats missed by existing tools whose outputs often contain many invalid cases. detectIR is open source and its source code is freely available at: https://sourceforge.net/projects/detectir.

Invariant Poisson-Nijenhuis structures on Lie groups and classification

NASA Astrophysics Data System (ADS)

Ravanpak, Zohreh; Rezaei-Aghdam, Adel; Haghighatdoost, Ghorbanali

We study right-invariant (respectively, left-invariant) Poisson-Nijenhuis structures (P-N) on a Lie group G and introduce their infinitesimal counterpart, the so-called r-n structures on the corresponding Lie algebra 𝔤. We show that r-n structures can be used to find compatible solutions of the classical Yang-Baxter equation (CYBE). Conversely, two compatible r-matrices from which one is invertible determine an r-n structure. We classify, up to a natural equivalence, all r-matrices and all r-n structures with invertible r on four-dimensional symplectic real Lie algebras. The result is applied to show that a number of dynamical systems which can be constructed by r-matrices on a phase space whose symmetry group is Lie group a G, can be specifically determined.

Femtosecond laser-induced inverted microstructures inside glasses by tuning refractive index of objective's immersion liquid.

PubMed

Luo, Fangfang; Song, Juan; Hu, Xiao; Sun, Haiyi; Lin, Geng; Pan, Huaihai; Cheng, Ya; Liu, Li; Qiu, Jianrong; Zhao, Quanzhong; Xu, Zhizhan

2011-06-01

We report the formation of inverted microstructures inside glasses after femtosecond laser irradiation by tuning the refractive index contrast between the immersion liquid and the glass sample. By using water as well as 1-bromonaphthalene as immersion liquids, microstructures with similar shape but opposite directions are induced after femtosecond laser irradiation. Interestingly, the elemental distribution in the induced structures is also inverted. The simulation of laser intensity distribution along the laser propagation direction indicates that the interfacial spherical aberration effect is responsible for the inversion of microstructures and elemental distribution. © 2011 Optical Society of America

Two-dimensional joint inversion of Magnetotelluric and local earthquake data: Discussion on the contribution to the solution of deep subsurface structures

NASA Astrophysics Data System (ADS)

Demirci, İsmail; Dikmen, Ünal; Candansayar, M. Emin

2018-02-01

Joint inversion of data sets collected by using several geophysical exploration methods has gained importance and associated algorithms have been developed. To explore the deep subsurface structures, Magnetotelluric and local earthquake tomography algorithms are generally used individually. Due to the usage of natural resources in both methods, it is not possible to increase data quality and resolution of model parameters. For this reason, the solution of the deep structures with the individual usage of the methods cannot be fully attained. In this paper, we firstly focused on the effects of both Magnetotelluric and local earthquake data sets on the solution of deep structures and discussed the results on the basis of the resolving power of the methods. The presence of deep-focus seismic sources increase the resolution of deep structures. Moreover, conductivity distribution of relatively shallow structures can be solved with high resolution by using MT algorithm. Therefore, we developed a new joint inversion algorithm based on the cross gradient function in order to jointly invert Magnetotelluric and local earthquake data sets. In the study, we added a new regularization parameter into the second term of the parameter correction vector of Gallardo and Meju (2003). The new regularization parameter is enhancing the stability of the algorithm and controls the contribution of the cross gradient term in the solution. The results show that even in cases where resistivity and velocity boundaries are different, both methods influence each other positively. In addition, the region of common structural boundaries of the models are clearly mapped compared with original models. Furthermore, deep structures are identified satisfactorily even with using the minimum number of seismic sources. In this paper, in order to understand the future studies, we discussed joint inversion of Magnetotelluric and local earthquake data sets only in two-dimensional space. In the light of these results and by means of the acceleration on the three-dimensional modelling and inversion algorithms, it is thought that it may be easier to identify underground structures with high resolution.

Low nonalloyed Ohmic contact resistance to nitride high electron mobility transistors using N-face growth

NASA Astrophysics Data System (ADS)

Wong, Man Hoi; Pei, Yi; Palacios, Tomás; Shen, Likun; Chakraborty, Arpan; McCarthy, Lee S.; Keller, Stacia; DenBaars, Steven P.; Speck, James S.; Mishra, Umesh K.

2007-12-01

Nonalloyed Ohmic contacts on Ga-face n+-GaN/AlGaN/GaN high electron mobility transistor (HEMT) structures typically have significant contact resistance to the two-dimensional electron gas (2DEG) due to the AlGaN barrier. By growing the HEMT structure inverted on the N-face, electrons from the contacts were able to access the 2DEG without going through an AlGaN layer. A low contact resistance of 0.16Ωmm and specific contact resistivity of 5.5×10-7Ωcm2 were achieved without contact annealing on the inverted HEMT structure.

Cyclotron resonance in HgTe/CdTe-based heterostructures in high magnetic fields

PubMed Central

2012-01-01

Cyclotron resonance study of HgTe/CdTe-based quantum wells with both inverted and normal band structures in quantizing magnetic fields was performed. In semimetallic HgTe quantum wells with inverted band structure, a hole cyclotron resonance line was observed for the first time. In the samples with normal band structure, interband transitions were observed with wide line width due to quantum well width fluctuations. In all samples, impurity-related magnetoabsorption lines were revealed. The obtained results were interpreted within the Kane 8·8 model, the valence band offset of CdTe and HgTe, and the Kane parameter EP being adjusted. PMID:23013642

Three-dimensional Upper Crustal Velocity and Attenuation Structures of the Central Tibetan Plateau from Local Earthquake Tomography

NASA Astrophysics Data System (ADS)

Zhou, B.; Liang, X.; Lin, G.; Tian, X.; Zhu, G.; Mechie, J.; Teng, J.

2017-12-01

A series of V-shaped conjugate strike-slip faults are the most spectacular geologic features in the central Tibetan plateau. A previous study suggested that this conjugate strike-slip fault system accommodates the east-west extension and coeval north-south contraction. Another previous study suggested that the continuous convergence between the Indian and Eurasian continents and the eastward asthenospheric flow generated lithospheric paired general-shear (PGS) deformation, which then caused the development of conjugate strike-slip faults in central Tibet. Local seismic tomography can image three dimensional upper-crustal velocity and attenuation structures in central Tibet, which will provide us with more information about the spatial distribution of physical properties and compositional variations around the conjugate strike-slip fault zone. Ultimately, this information could improve our understanding of the development mechanism of the conjugate strike-slip fault system. In this study, we collected 6,809 Pg and 2,929 Sg arrival times from 414 earthquakes recorded by the temporary SANDWICH and permanent CNSN networks from November 2013 to November 2015. We also included 300 P and 17 S arrival times from 12 shots recorded by the INDEPTH III project during the summer of 1998 in the velocity tomography. We inverted for preliminary Vp and Vp/Vs models using the SIMUL2000 tomography algorithm, and then relocated the earthquakes with these preliminary velocity models. After that, we inverted for the final velocity models with these improved source locations and origin times. After the velocity inversion, we performed local attenuation tomography using t* measurements from the same dataset with an already existing approach. There are correlated features in the velocity and attenuation structures. From the surface to 10 km depth, the study area is dominated by high Vp and Qp anomalies. However, from 10 km to 20 km depth, there is a low Vp and Qp zone distributed along the conjugate strike-slip fault zone, with high Vp and Qp zones located north and south of the low Vp and Qp region. The prominent low velocity and Qp features in the image might reflect depth variations of physical properties or compositional differences related to the development of the conjugate strike-slip fault zone.

Direct and inverted nematic dispersions for soft matter photonics.

PubMed

Muševič, I; Skarabot, M; Humar, M

2011-07-20

General properties and recent developments in the field of nematic colloids and emulsions are discussed. The origin and nature of pair colloidal interactions in the nematic colloids are explained and an overview of the stable colloidal 2D crystalline structures and superstructures discovered so far is given. The nature and role of topological defects in the nematic colloids is discussed, with an emphasis on recently discovered entangled colloidal structures. Applications of inverted nematic emulsions and binding force mechanisms in nematic colloids for soft matter photonic devices are discussed.

Thermal management and performance evaluation of a dual bi-directional, soft-switched IGBT-based inverter for the 1st autonomous microgrid power system in Taiwan under various operating conditions

NASA Astrophysics Data System (ADS)

Chang, Tien-Chan; Fuh, Yiin-Kuen; Lu, Hong-Yi; Tu, Sheng-Xun

2016-06-01

The thermal management of the inverter system is of great importance since very high voltage/current will be switched intermittently and/or continuously and high temperature is excruciably detrimental to the service life of electronics, especially for the switching devices such as insulated gate bipolar transistor (IGBT). In this study, a newly developed dual bi-directional IGBT-based inverter in conjunction with autonomous microgrid system is investigated with particular focus on the thermal management and performance evaluation under various operation conditions. Locally enhanced heat transfer approach such as oblique orientation and heat dissipating materials are experimentally investigated. The studied inverter system is initially packaged by a galvanized steel plate (size 62 × 48 × 18 cm) and the switching power is set in the range of 0.5-3 kW. The module is operated at the switching and pulse frequencies of 60 Hz and 20 kHz, respectively. The adoption of heat dissipating material in either paste or film form had experimentally shown to possess the flexibility tailoring heat transfer performance locally. Experimental studies of heat dissipating film with various hotspot scenarios showed that the temperature difference can be appreciably reduced as much as 13.1 and 15.4 °C, respectively with facilitation of one- and two-layers of heat dissipating film. From the measurement results, the measured peak temperature is highly dominated by the thickness of heat dissipating film, showing the dominance of thickness-dependent thermal resistance and resultant heat accumulation phenomena.

Dorsal Failures: From Saddle Deformity to Pollybeak.

PubMed

Hamilton, Grant S

2018-06-01

The nasal dorsum is an important component of a rhinoplasty and may be the primary motivation for seeking surgery. The nasal dorsum is a complex three-dimensional shape that is shrouded by local anesthetic and edema during surgery. This makes an accurate assessment of the surgical changes challenging. Complications related to dorsal modification include imbalances from over- or underresection of the structures of the nasal dorsum, inadequate or overaugmentation, an open-roof deformity, pollybeak, saddle nose, inverted-V, warped cartilage, visible grafts, contour problems, graft malposition, and extrusion. This review will discuss the common problems that can occur with dorsal modification during rhinoplasty. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

3D Velocity Structure in Southern Haiti from Local Earthquake Tomography

NASA Astrophysics Data System (ADS)

Douilly, R.; Ellsworth, W. L.; Kissling, E. H.; Freed, A. M.; Deschamps, A.; de Lepinay, B. M.

2016-12-01

We investigate 3D local earthquake tomography for high-quality travel time arrivals from aftershocks following the 2010 M7.0 Haiti earthquake on the Léogâne fault. The data were recorded by 35 stations, including 19 ocean bottom seismometers, from which we selected 595 events to simultaneously invert for hypocenter location and 3D Vp and Vs velocity structures in southern Haiti. We performed several resolution tests and concluded that clear features can be recovered to a depth of 15 km. At 5km depth we distinguish a broad low velocity zone in the Vp and Vs structure offshore near Gonave Island, which correlate with layers of marine sediments. Results show a pronounced low velocity zone in the upper 5 km across the city of Léogâne, which is consistent with the sedimentary basin location from geologic map. At 10 km depth, we detect a low velocity anomaly offshore near the Trois Baies fault and a NW-SE directed low velocity zone onshore across Petit-Goâve and Jacmel, which is consistent with a suspected fault from a previous study and that we refer to it in our study as the Petit-Goâve-Jacmel fault (PGJF). These observations suggest that low velocity structures delineate fault structures and the sedimentary basins across the southern peninsula, which is extremely useful for seismic hazard assessment in Haiti.

Small molecule solution-processed bulk heterojunction solar cells with inverted structure using porphyrin donor

NASA Astrophysics Data System (ADS)

Yamamoto, Takaki; Hatano, Junichi; Nakagawa, Takafumi; Yamaguchi, Shigeru; Matsuo, Yutaka

2013-01-01

Utilizing tetraethynyl porphyrin derivative (TE-Por) as a small molecule donor material, we fabricated a small molecule solution-processed bulk heterojunction (BHJ) solar cell with inverted structure, which exhibited 1.6% power conversion efficiency (JSC (short-circuit current) = 4.6 mA/cm2, VOC (open-circuit voltage) = 0.90 V, and FF (fill factor) = 0.39) in the device configuration indium tin oxide/TiOx (titanium sub-oxide)/[6,6]-phenyl-C61-butyric acid methyl ester:TE-Por (5:1)/MoOx (molybdenum sub-oxide)/Au under AM1.5 G illumination at 100 mW/cm2. Without encapsulation, the small molecule solution-processed inverted BHJ solar cell also showed remarkable durability to air, where it kept over 73% of its initial power conversion efficiency after storage for 28 days under ambient atmosphere in the dark.

Application of Microtremor Survey Methods to Determine the Shallow Crustal S-wave Velocity Structure beneath the Wudalianchi Weishan Volcano Area

NASA Astrophysics Data System (ADS)

Zhang, B.; LI, Z.; Chu, R.

2015-12-01

Ambient noise has been proven particularly effective in imaging Earth's crust and uppermost mantle on local, regional and global scales, as well as in monitoring temporal variations of the Earth interior and determining earthquake ground truth location. Previous studies also have shown that the Microtremor Survey Method is effective to map the shallow crustal structure. In order to obtain the shallow crustal velocity structure beneath the Wudalianchi Weishan volcano area, an array of 29 new no-cable digital geophones were deployed for three days at the test site (3km×3km) for recording continuously seismic noise. Weishan volcano is located in the far north of Wudalianchi Volcanoes, the volcanic cone is composed of basaltic lava and the volcano area covered by a quaternary sediments layer (gray and black loam, brown and yellow loam, sandy loam). Accurate shallow crustal structure, particularly sedimentary structure model can improve the accuracy of location of volcanic earthquakes and structural imaging. We use ESPAC method, which is one of Microtremor Survey Methods, to calculate surface wave phase velocity dispersion curves between station pairs. A generalized 2-D linear inversion code that is named Surface Wave Tomography (SWT) is adopted to invert phase velocity tomographic maps in 2-5 Hz periods band. On the basis of a series of numerical tests, the study region is parameterized with a grid spacing of 0.1km×0.1km, all damping parameters and regularization are set properly to ensure relatively smooth results and small data misfits as well. We constructed a 3D Shallow Crustal S-wave Velocity model in the area by inverting the phase velocity dispersion curves at each node adopting an iterative linearized least-square inversion scheme of surf96. The tomography model is useful in interpreting volcanic features.

Translocation and gross deletion breakpoints in human inherited disease and cancer II: Potential involvement of repetitive sequence elements in secondary structure formation between DNA ends.

PubMed

Chuzhanova, Nadia; Abeysinghe, Shaun S; Krawczak, Michael; Cooper, David N

2003-09-01

Translocations and gross deletions are responsible for a significant proportion of both cancer and inherited disease. Although such gene rearrangements are nonuniformly distributed in the human genome, the underlying mutational mechanisms remain unclear. We have studied the potential involvement of various types of repetitive sequence elements in the formation of secondary structure intermediates between the single-stranded DNA ends that recombine during rearrangements. Complexity analysis was used to assess the potential of these ends to form secondary structures, the maximum decrease in complexity consequent to a gross rearrangement being used as an indicator of the type of repeat and the specific DNA ends involved. A total of 175 pairs of deletion/translocation breakpoint junction sequences available from the Gross Rearrangement Breakpoint Database [GRaBD; www.uwcm.ac.uk/uwcm/mg/grabd/grabd.html] were analyzed. Potential secondary structure was noted between the 5' flanking sequence of the first breakpoint and the 3' flanking sequence of the second breakpoint in 49% of rearrangements and between the 5' flanking sequence of the second breakpoint and the 3' flanking sequence of the first breakpoint in 36% of rearrangements. Inverted repeats, inversions of inverted repeats, and symmetric elements were found in association with gross rearrangements at approximately the same frequency. However, inverted repeats and inversions of inverted repeats accounted for the vast majority (83%) of deletions plus small insertions, symmetric elements for one-half of all antigen receptor-mediated translocations, while direct repeats appear only to be involved in mediating simple deletions. These findings extend our understanding of illegitimate recombination by highlighting the importance of secondary structure formation between single-stranded DNA ends at breakpoint junctions. Copyright 2003 Wiley-Liss, Inc.

Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

PubMed

Maeda, Y

1994-08-10

An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

The electrification of stratiform anvils

NASA Astrophysics Data System (ADS)

Boccippio, Dennis J.

1997-10-01

Stratiform precipitation regions accompany convective activity on many spatial scales. The electrification of these regions is anomalous in a number of ways. Surface and above-cloud fields are often 'inverted' from normal thunderstorm conditions. Unusually large, bright, horizontal 'spider' lightning and high current and charge transfer positive cloud-to-ground (CC) lightning dominates in these regions. Mesospheric 'red sprite' emissions have to date been observed exclusively over stratiform cloud shields. We postulate that a dominant 'inverted dipole' charge structure may account for this anomalous electrification. This is based upon laboratory observations of charge separation which show that in low liquid water content (LWC) environments, or dry but ice- supersaturated environments, precipitation ice tends to charge positively (instead of negatively) upon collision with smaller crystals. Under typical stratiform cloud conditions, liquid water should be depleted and this charging regime favored. An inverted dipole would be the natural consequence of large-scale charge separation (net flux divergence of charged ice), given typical hydrometeor profiles. The inverted dipole hypothesis is tested using radar and electrical observations of four weakly organized, late- stage systems in Orlando, Albuquerque and the Western Pacific. Time-evolving, area-average vertical velocity profiles are inferred from single Doppler radar data. These profiles provide the forcing for a 1-D steady state micro-physical retrieval, which yields vertical hydrometeor profiles and ice/water saturation conditions. The retrieved microphysical parameters are then combined with laboratory charge transfer measurements to infer the instantaneous charging behavior of the systems. Despite limitations in the analysis technique, the retrievals yield useful results. Total charge transfer drops only modestly as the storm enters the late (stratiform) stage, suggesting a continued active generator is plausible. Generator currents show an enhanced lowermost inverted dipole charging structure, which we may infer will result in a comparable inverted dipole charge structure, consistent with surface, in-situ and remote observations. Fine-scale vertical variations in ice and liquid water content may yield multipolar generator current profiles, despite unipolar charge transfer regimes. This suggests that multipoles observed in balloon soundings may not necessarily conflict with the simple ice-ice collisional charge separation mechanism. Overall, the results are consistent with, but not proof of, the inverted dipole model. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253- 1690.)

Multilevel DC Link Inverter for Brushless Permanent Magnet Motors with Very Low Inductance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, G.J.

2001-10-29

Due to their long effective air gaps, permanent magnet motors tend to have low inductance. The use of ironless stator structure in present high power PM motors (several tens of kWs) reduces the inductance even further (< 100 {micro}H). This low inductance imposes stringent current regulation demands for the inverter to obtain acceptable current ripple. An analysis of the current ripple for these low inductance brushless PM motors shows that a standard inverter with the most commonly used IGBT switching devices cannot meet the current regulation demands and will produce unacceptable current ripples due to the IGBT's limited switching frequency.more » This paper introduces a new multilevel dc link inverter, which can dramatically reduce the current ripple for brushless PM motor drives. The operating principle and design guidelines are included.« less

[Convergent origin of repeats in genes coding for globular proteins. An analysis of the factors determining the presence of inverted and symmetrical repeats].

PubMed

Solov'ev, V V; Kel', A E; Kolchanov, N A

1989-01-01

The factors, determining the presence of inverted and symmetrical repeats in genes coding for globular proteins, have been analysed. An interesting property of genetical code has been revealed in the analysis of symmetrical repeats: the pairs of symmetrical codons corresponded to pairs of amino acids with mostly similar physical-chemical parameters. This property may explain the presence of symmetrical repeats and palindromes only in genes coding for beta-structural proteins-polypeptides, where amino acids with similar physical-chemical properties occupy symmetrical positions. A stochastic model of evolution of polynucleotide sequences has been used for analysis of inverted repeats. The modelling demonstrated that only limiting of sequences (uneven frequencies of used codons) is enough for arising of nonrandom inverted repeats in genes.

Buckling Design Studies of Inverted, Oblate Bulkheads for a Propellant Tank

NASA Technical Reports Server (NTRS)

Smeltzer, Stanley S., III; Bowman, Lynn M.

2002-01-01

An investigation of the deformation and buckling characteristics of a composite, oblate bulkhead that has an inverted geometry and is subjected to pressure-only loading is presented for three bulkhead geometries and thicknesses. The effects of a stiffening support ring at the bulkhead to cylinder interface are also evaluated. Buckling analyses conducted using the axisymmetric shell code BOSOR4 are discussed for several bulkhead configurations. These results are analytically verified using results from the Structural Analysis of General Shells (STAGS) code for a selected bulkhead configuration. The buckling characterization of an inverted, oblate bulkhead requires careful attention as small changes in bulkhead parameters can have a significant effect on the critical buckling load. Comparison of BOSOR4 and STAGS results provided a very good correlation between the two analysis methods. In addition, the analysis code BOSOR4 was found to be an efficient sizing tool that is useful during the preliminary design stage of a practical shell structure. Together, these two aspects should give the design engineer confidence in sizing these stability critical structures. Additional characterization is warranted, especially for a composite tank structure, since only one bulkhead configuration was examined closely.

Inverted organic electronic and optoelectronic devices

NASA Astrophysics Data System (ADS)

Small, Cephas E.

The research and development of organic electronics for commercial application has received much attention due to the unique properties of organic semiconductors and the potential for low-cost high-throughput manufacturing. For improved large-scale processing compatibility and enhanced device stability, an inverted geometry has been employed for devices such as organic light emitting diodes and organic photovoltaic cells. These improvements are attributed to the added flexibility to incorporate more air-stable materials into the inverted device geometry. However, early work on organic electronic devices with an inverted geometry typically showed reduced device performance compared to devices with a conventional structure. In the case of organic light emitting diodes, inverted devices typically show high operating voltages due to insufficient carrier injection. Here, a method for enhancing hole injection in inverted organic electronic devices is presented. By incorporating an electron accepting interlayer into the inverted device, a substantial enhancement in hole injection efficiency was observed as compared to conventional devices. Through a detailed carrier injection study, it is determined that the injection efficiency enhancements in the inverted devices are due to enhanced charge transfer at the electron acceptor/organic semiconductor interface. A similar situation is observed for organic photovoltaic cells, in which devices with an inverted geometry show limited carrier extraction in early studies. In this work, enhanced carrier extraction is demonstrated for inverted polymer solar cells using a surface-modified ZnO-polymer composite electron-transporting layer. The insulating polymer in the composite layer inhibited aggregation of the ZnO nanoparticles, while the surface-modification of the composite interlayer improved the electronic coupling with the photoactive layer. As a result, inverted polymer solar cells with power conversion efficiencies of over 8% were obtained. To further study carrier extraction in inverted polymer solar cells, the active layer thickness dependence of the efficiency was investigated. For devices with active layer thickness < 200 nm, power conversion efficiencies over 8% was obtained. This result is important for demonstrating improved large-scale processing compatibility. Above 200 nm, significant reduction in cell efficiency were observed. A detailed study of the loss processes that contributed to the reduction in efficiency for thick-film devices are presented.

Stochastic seismic inversion based on an improved local gradual deformation method

NASA Astrophysics Data System (ADS)

Yang, Xiuwei; Zhu, Peimin

2017-12-01

A new stochastic seismic inversion method based on the local gradual deformation method is proposed, which can incorporate seismic data, well data, geology and their spatial correlations into the inversion process. Geological information, such as sedimentary facies and structures, could provide significant a priori information to constrain an inversion and arrive at reasonable solutions. The local a priori conditional cumulative distributions at each node of model to be inverted are first established by indicator cokriging, which integrates well data as hard data and geological information as soft data. Probability field simulation is used to simulate different realizations consistent with the spatial correlations and local conditional cumulative distributions. The corresponding probability field is generated by the fast Fourier transform moving average method. Then, optimization is performed to match the seismic data via an improved local gradual deformation method. Two improved strategies are proposed to be suitable for seismic inversion. The first strategy is that we select and update local areas of bad fitting between synthetic seismic data and real seismic data. The second one is that we divide each seismic trace into several parts and obtain the optimal parameters for each part individually. The applications to a synthetic example and a real case study demonstrate that our approach can effectively find fine-scale acoustic impedance models and provide uncertainty estimations.

Theoretical study of high-Q Fano resonance and extrinsic chirality in an ultrathin Babinet-inverted metasurface

NASA Astrophysics Data System (ADS)

Wang, Feng; Wang, Zhengping; Shi, Jinhui

2014-10-01

A high-Q Fano resonance and giant extrinsic chirality have been demonstrated in an ultrathin Babinet-inverted metasurface composed of asymmetrical split ring apertures (ASRAs) perforated through a metal plate based on the full-wave simulations. The performance of the Fano resonance at normal incidence strongly depends on the asymmetry of the ASRA. The quality factor is larger than 1000 and the local field enhancement is an order of 104. For oblique incidence, giant extrinsic chirality can be achieved in the Babinet-inverted metasurface. It reveals a cross-polarization transmission band with a ripple-free peak and also a spectrum split for large angles of incidence. The electromagnetic response of the metasurface can be easily tuned via angles of incidence and asymmetry. The proposed ASRA metasurface is of importance to develop many metamaterial-based devices, such as filters and circular polarizers.

Coherence of structural visual cues and pictorial gravity paves the way for interceptive actions.

PubMed

Zago, Myrka; La Scaleia, Barbara; Miller, William L; Lacquaniti, Francesco

2011-09-20

Dealing with upside-down objects is difficult and takes time. Among the cues that are critical for defining object orientation, the visible influence of gravity on the object's motion has received limited attention. Here, we manipulated the alignment of visible gravity and structural visual cues between each other and relative to the orientation of the observer and physical gravity. Participants pressed a button triggering a hitter to intercept a target accelerated by a virtual gravity. A factorial design assessed the effects of scene orientation (normal or inverted) and target gravity (normal or inverted). We found that interception was significantly more successful when scene direction was concordant with target gravity direction, irrespective of whether both were upright or inverted. This was so independent of the hitter type and when performance feedback to the participants was either available (Experiment 1) or unavailable (Experiment 2). These results show that the combined influence of visible gravity and structural visual cues can outweigh both physical gravity and viewer-centered cues, leading to rely instead on the congruence of the apparent physical forces acting on people and objects in the scene.

One-step Maskless Fabrication and Optical Characterization of Silicon Surfaces with Antireflective Properties and a White Color Appearance

PubMed Central

Schneider, Ling; Feidenhans’l, Nikolaj A.; Telecka, Agnieszka; Taboryski, Rafael J.

2016-01-01

We report a simple one-step maskless fabrication of inverted pyramids on silicon wafers by reactive ion etching. The fabricated surface structures exhibit excellent anti-reflective properties: The total reflectance of the nano inverted pyramids fabricated by our method can be as low as 12% without any anti-reflective layers, and down to only 0.33% with a silicon nitride coating. The results from angle resolved scattering measurements indicate that the existence of triple reflections is responsible for the reduced reflectance. The surfaces with the nano inverted pyramids also exhibit a distinct milky white color. PMID:27725703

Development of inverted metamorphic isograds in the western metamorphic belt, Juneau, Alaska

USGS Publications Warehouse

Himmelberg, G.R.; Brew, D.A.; Ford, A.B.

1991-01-01

An inverted metamorphic gradient is preserved in the western metamorphic belt near Juneau, Alaska. Detailed mapping of pelitic single-mineral isograds, systematic changes in mineral assemblages, and silicate geothermometry indicate that thermal peak metamorphic conditions increase structurally upward over a distance of about 8 km. Silicate geobarometry suggests that the thermal peak metamorphism occurred under pressures of 9-11 kbar. Our preferred interpretation of the cause of the inverted gradient is that it formed during compression of a thickened wedge of relatively wet and cool rocks in response to heat flow associated with the formation and emplacement of tonalite sill magma. -from Authors

Electrical conductivity structure of the mantle derived from inversion of geomagnetic observatory data: implications for lateral variations in temperature, composition and water content.

NASA Astrophysics Data System (ADS)

Munch, Federico; Grayver, Alexander; Khan, Amir; Kuvshinov, Alexey

2017-04-01

As most of Earth's interior remains geochemically unsampled, geophysical techniques based on seismology, geodesy, gravimetry, and electromagnetic studies play prominent roles because of their ability to sense structure at depth. Although seismic tomography maps show a variety of structures, separating thermal and compositional contributions from seismic velocities alone still remains a challenging task. Alternatively, as electrical conductivity is sensitive to temperature, chemical composition, oxygen fugacity, water content, and the presence of melt, it can serve for determining chemistry, mineralogy, and physical structure of the deep mantle. In this work we estimate and invert local C-responses (period range 3-100 days) for a number of worldwide geomagnetic observatories to map lateral variations of electrical conductivity in Earth's mantle (400-1600 km depth). The obtained conductivity profiles are interpreted in terms of basalt fraction in a basalt-harzburgite mixture, temperature structure, and water content variations. Interpretation is based on a self-consistent thermodynamic calculation of mineral phase equilibria, electrical conductivity databases, and probabilistic inverse methods.

Feeder Voltage Regulation with High-Penetration PV Using Advanced Inverters and a Distribution Management System: A Duke Energy Case Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmintier, Bryan; Giraldez, Julieta; Gruchalla, Kenny

2016-11-01

Duke Energy, Alstom Grid, and the National Renewable Energy Laboratory teamed up to better understand the impacts of solar photovoltaics (PV) on distribution system operations. The core goal of the project is to compare the operational - specifically, voltage regulation - impacts of three classes of PV inverter operations: 1.) Active power only (Baseline); 2.) Local inverter control (e.g., PF...not equal...1, Q(V), etc.); and 3.) Integrated volt-VAR control (centralized through the distribution management system). These comparisons were made using multiple approaches, each of which represents an important research-and-development effort on its own: a) Quasi-steady-state time-series modeling for approximately 1 yearmore » of operations using the Alstom eTerra (DOTS) system as a simulation engine, augmented by Python scripting for scenario and time-series control and using external models for an advanced inverter; b) Power-hardware-in-the-loop (PHIL) testing of a 500-kVA-class advanced inverter and traditional voltage regulating equipment. This PHIL testing used cosimulation to link full-scale feeder simulation using DOTS in real time to hardware testing; c) Advanced visualization to provide improved insights into time-series results and other PV operational impacts; and d) Cost-benefit analysis to compare the financial and business-model impacts of each integration approach.« less

Joint Local/Teleseismic Tomographic Inversion in Taiwan Using TAIGER and Other Data

NASA Astrophysics Data System (ADS)

Lee, E.; Wu, F. T.; Huang, B.; Liang, W.; Wang, C.; Rawlinson, N.; Okaya, D. A.

2008-12-01

Taiwan, one of the most active orogenic belts, is at the intersection of two subduction zones. In southern Taiwan, the South China Sea Slab (SCSS), part of Eurasian Plate (EP), subducts beneath the Luzon arc along the Manila trench. In northern Taiwan, the Philippine Sea Plate (PSP) subducts beneath the Ryukyu arc along the Ryukyu trench. The thin skinned model and lithospheric deformation model have been proposed to explain the formation of orogeny. To distinguish between these two geodynamically possible processes, imaging of the deep structures below Taiwan is necessary. In this study, explosion data, local/regional earthquakes and teleseisms are used to invert the velocity structures of Taiwan from surface to about 150 km. Temporary passive broadband (on land and at the ocean bottom), active sources array datasets of the TAIGER (TAiwan Integrated GEodynamics Research) project and permanent array datasets of the BATS (Broadband Array in Taiwan for Seismology) and CWB (Central Weather Bureau) are used in this study. FMTOMO (fast marching tomography) of Rawlinson et al. (2006) is employed to invert the 3D P-wavespeed beneath Taiwan. The derived velocity perturbations dVp (dVp= Vfinal-Vinital) are clearly related to geology and tectonics. At shallow depth (< 10km), dVp >0 under the Central Range (Pre-Tertiary metamorphic rocks) and dVp < 0 under the Foothills (Pliocene sedimentary). Below a depth about 20 km, the placement of the high and low anomalies is reversed, i.e., dVp>0 under the Foothills and dVp<0 under the Central Range; the low velocity core of the Central Ranges extend down to about 50 km, forming the mountain root. A steeply dipping high velocity zone lies under the thickening 'mountain root' in central Taiwan. In southern Taiwan, the high velocity zone dips eastward coinciding with the Benioff Zone. The geometry of the high velocity zones in the upper mantle are key to understanding the Taiwan orogeny.

Optical second harmonic images of 90 deg domain structure in BaTiO3 and periodically inverted antiparallel domains in LiTaO3

NASA Astrophysics Data System (ADS)

Uesu, Y.; Kurimura, S.; Yamamoto, Y.

1995-04-01

Applied is a microscope to observations of 90 deg ferroelectric domain structure in BaTiO3 and inverted periodically are ferroelectric domains in LiTaO3. It is founded that the second harmonic generation microscope gives information which cannot be obtained by ordinary optical microscopes. The developed nonlinear optical microscope builds two dimensional second harmonic image of a specimen with inhomogenous distribution of d(sub ijk) and applied the microscope to observations of inhomogeneity in some nonlinear-optical organic microcrystals.

Fabrication of 20.19% Efficient Single-Crystalline Silicon Solar Cell with Inverted Pyramid Microstructure.

PubMed

Zhang, Chunyang; Chen, Lingzhi; Zhu, Yingjie; Guan, Zisheng

2018-04-03

This paper reports inverted pyramid microstructure-based single-crystalline silicon (sc-Si) solar cell with a conversion efficiency up to 20.19% in standard size of 156.75 × 156.75 mm 2 . The inverted pyramid microstructures were fabricated jointly by metal-assisted chemical etching process (MACE) with ultra-low concentration of silver ions and optimized alkaline anisotropic texturing process. And the inverted pyramid sizes were controlled by changing the parameters in both MACE and alkaline anisotropic texturing. Regarding passivation efficiency, the textured sc-Si with normal reflectivity of 9.2% and inverted pyramid size of 1 μm was used to fabricate solar cells. The best batch of solar cells showed a 0.19% higher of conversion efficiency and a 0.22 mA cm -2 improvement in short-circuit current density, and the excellent photoelectric property surpasses that of the same structure solar cell reported before. This technology shows great potential to be an alternative for large-scale production of high efficient sc-Si solar cells in the future.

Seismicity and structure of Akutan and Makushin Volcanoes, Alaska, using joint body and surface wave tomography

DOE PAGES

Syracuse, E. M.; Maceira, M.; Zhang, H.; ...

2015-02-18

Joint inversions of seismic data recover models that simultaneously fit multiple constraints while playing upon the strengths of each data type. Here, we jointly invert 14 years of local earthquake body wave arrival times from the Alaska Volcano Observatory catalog and Rayleigh wave dispersion curves based upon ambient noise measurements for local V p, V s, and hypocentral locations at Akutan and Makushin Volcanoes using a new joint inversion algorithm.The velocity structure and relocated seismicity of both volcanoes are significantly more complex than many other volcanoes studied using similar techniques. Seismicity is distributed among several areas beneath or beyond themore » flanks of both volcanoes, illuminating a variety of volcanic and tectonic features. The velocity structures of the two volcanoes are exemplified by the presence of narrow high-V p features in the near surface, indicating likely current or remnant pathways of magma to the surface. A single broad low-V p region beneath each volcano is slightly offset from each summit and centered at approximately 7 km depth, indicating a potential magma chamber, where magma is stored over longer time periods. Differing recovery capabilities of the Vp and Vs datasets indicate that the results of these types of joint inversions must be interpreted carefully.« less

Morphological keys in the differential diagnosis of bladder inverted papilloma. Study of two types, trabecular and glandular.

PubMed

Sabater Marco, Vicente; Navalón Verdejo, Pedro; Morera Faet, Arturo

2012-09-01

Inverted papilloma of the urinary bladder is an uncommon urothelial neoplasm that may be specially difficult to distinguish from urothelial carcinoma. Two patients with obstructive symptoms and hematuria have been studied. In the transurethral resection, accidentally, one showed a papillary lesion in the context of nodular hyperplasia of the prostate, where as the other showed a polypoid tumor of the urinary bladder Histologically, in both cases, a bladder inverted papilloma was demonstrated, originating from the surface transitional epithelium. Basal cells exhibited peripheral palisading pattern in the trabecular form. In the glandular type, Dogiel or umbrella cells into the gland-like structures, were recognized. Immunohistochemical stains for p53 and Ki-67 were negative. Umbrella cells were positive for cytokeratin 20. Two cases of bladder inverted papilloma with relevant morphological aspects are presented, which we consider useful for the differential diagnosis with urothelial carcinoma.

Development of a digital solar simulator based on full-bridge converter

NASA Astrophysics Data System (ADS)

Liu, Chen; Feng, Jian; Liu, Zhilong; Tong, Weichao; Ji, Yibo

2014-02-01

With the development of solar photovoltaic, distribution schemes utilized in power grid had been commonly application, and photovoltaic (PV) inverter is an essential equipment in grid. In this paper, a digital solar simulator based on full-bridge structure is presented. The output characteristic curve of system is electrically similar to silicon solar cells, which can greatly simplify research methods of PV inverter, improve the efficiency of research and development. The proposed simulator consists on a main control board based on TM320F28335, phase-shifted zero-voltage-switching (ZVS) DC-DC full-bridge converter and voltage and current sampling circuit, that allows emulating the voltage-current curve with the open-circuit voltage (Voc) of 900V and the short-circuit current (Isc) of 18A .When the system connected to a PV inverter, the inverter can quickly track from the open-circuit to the maximum power point and keep stability.

Influences of device structures on microstructure-correlated photovoltaic characteristics of organic solar cells

NASA Astrophysics Data System (ADS)

Wu, Fu-Chiao; Yang, Cheng-Chi; Tseng, Po-Tsung; Chou, Wei-Yang; Cheng, Horng-Long

2017-02-01

Photovoltaic characteristics of organic solar cells (OSCs) are correlated with microstructural qualities of active layers (ALs). Numerous efforts focused on improving process conditions of ALs to attain effective microstructures to achieve high-efficiency OSCs. Aside from AL process conditions, layer properties under AL can also influence microstructural qualities of AL. In this study, we adopted poly(3-hexylthiophene) (P3HT):(6,6)-phenyl C61-butyric acid methyl ester (PCBM) mixture as AL, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as hole extraction layer, and branched polyethyleneimine (BPEI) as electron extraction layer to prepare OSCs with different device structures, that is, normal type (PEDOT:PSS/P3HT:PCBM/BPEI) and inverted type (BPEI/P3HT:PCBM/PEDOT:PSS) structures. We discovered that although devices have similar layer components, they have different photovoltaic characteristics. Inverted devices demonstrated higher power conversion efficiency than normal devices. Various methods, including absorption spectroscopy and microscopy, were used to study AL microstructures of different devices. We observed that P3HT crystallites grown on BPEI had longer vertical size and shorter horizontal size compared with those grown on PEDOT:PSS; these properties could result from larger interfacial tension of P3HT with BPEI than with PEDOT:PSS. Observed shape of P3HT crystallites in inverted devices facilitated efficient charge transport to electrodes and suppressed current leakage. As a result, inverted devices generated improved photovoltaic performance.

Response of Pendulums to Translational and Rotational Components of Ground Motion

NASA Astrophysics Data System (ADS)

Graizer, V.; Kalkan, E.

2008-12-01

Dynamic response of most seismological instruments and many engineering structures to ground shaking can be represented via response of a pendulum (single-degree-of-freedom oscillator). Pendulum response is usually simplified by considering the input from uni-axial translational motion only. Complete ground motion however, includes not only translational components but also rotations (tilt and torsion). We consider complete equations of motion for three following types of pendulum: (i) conventional mass-on-rod, (ii) mass- on-spring type, and (iii) inverted (astatic), then their response sensitivities to each component of complex ground motion are examined. Inverted pendulums are used in seismology for more than 100 years, for example, classical Wiechert's horizontal seismograph built around 1905 and still used at some seismological observatories, and recent Guralp's horizontal seismometers CMG-40T and CMG-3T. Inverted pendulums also have significant importance for engineering applications where they are often used to simulate the dynamic response of various structural systems. The results of this study show that a horizontal pendulum similar to a modern accelerometer used in strong motion measurements is practically sensitive to translational motion and tilt only, while inverted pendulum is sensitive not only to translational components, but also to angular accelerations and tilt. For better understanding of the inverted pendulum's dynamic behavior under complex ground excitation, relative contribution of each component of motion on response variants is carefully isolated. The responses of pendulums are calculated in time-domain using close-form solution Duhamel's integral with complex input forcing functions. As compared to a common horizontal pendulum, response of an inverted pendulum is sensitive to acceleration of gravity and vertical acceleration when it reaches the level close to 1.0 g. Gravity effect introduces nonlinearity into the differential equation of motion, and results in shift of the frequency response to lower frequencies. The equations of inverted pendulum represent elastic response of pendulums (as material behavior), with nonlinearity created by time and amplitude dependence of equation coefficients. Sensitivity of inverted pendulum to angular acceleration of tilt is proportional to the length of a pendulum, and should be taken into consideration since it can produce significant effect especially for long pendulums, idealizing for instance, bridge piers, bents, elevated water tanks, telecommunication towers, etc.

Using Airborne Radar Stratigraphy to Model Surface Accumulation Anomaly and Basal Control over Deformed Basal Ice in Greenland

NASA Astrophysics Data System (ADS)

Das, I.; Bell, R. E.; Creyts, T. T.; Wolovick, M.

2013-12-01

Large deformed ice structures have been imaged at the base of northern Greenland ice sheet by IceBridge airborne radar. Numerous deformed structures lie along the base of both Petermann Glacier and Northeast Ice stream catchments covering 10-13% of the catchment area. These structures may be combinations of basal freeze-on and folded ice that overturns and inverts stratigraphy. In the interior, where the ice velocity is low, the radar imaged height of the deformed structures are frequently a significant fraction of the ice thickness. They are related to basal freeze on and stick-slip at the base of the ice sheet and may be triggered by subglacial water, sediments or local geological conditions. The larger ones (at times up to 700 m thick and 140 km long) perturb the ice stratigraphy and create prominent undulations on the ice surface and modify the local surface mass balance. Here, we investigate the relationship between the deformed structures and surface processes using shallow and deep ice radar stratigraphy. The surface undulations caused by the deformed structures modulate the pattern of local surface snow accumulation. Using normalized differences of several near-surface stratigraphic layers, we have calculated the accumulation anomaly over these deformed structures. The accumulation anomalies can be as high as 20% of the local surface accumulation over some of the larger surface depressions caused by these deformed structures. We observe distinct differences in the phases of the near-surface internal layers on the Petermann and Northeast catchments. These differences indicate that the deformed bodies over Petermann are controlled by conditions at the bed different from the Northeast Ice stream. The distinctly different near-surface stratigraphy over the deformed structures in the Petermann and Northeast catchments have opened up a number of questions including their formation and how they influence the ice dynamics, ice stratigraphy and surface mass balance. In this study we will model the different physical conditions at the bed and ice rheology from their distinct signatures in the near-surface strata. The results will identify the distinct mechanisms that form these bodies and their control over the surface morphology and snow accumulation.

Universal Sign Control of Coupling in Tight-Binding Lattices

NASA Astrophysics Data System (ADS)

Keil, Robert; Poli, Charles; Heinrich, Matthias; Arkinstall, Jake; Weihs, Gregor; Schomerus, Henning; Szameit, Alexander

2016-05-01

We present a method of locally inverting the sign of the coupling term in tight-binding systems, by means of inserting a judiciously designed ancillary site and eigenmode matching of the resulting vertex triplet. Our technique can be universally applied to all lattice configurations, as long as the individual sites can be detuned. We experimentally verify this method in laser-written photonic lattices and confirm both the magnitude and the sign of the coupling by interferometric measurements. Based on these findings, we demonstrate how such universal sign-flipped coupling links can be embedded into extended lattice structures to impose a Z2-gauge transformation. This opens a new avenue for investigations on topological effects arising from magnetic fields with aperiodic flux patterns or in disordered systems.

A compact light-sheet microscope for the study of the mammalian central nervous system

PubMed Central

Yang, Zhengyi; Haslehurst, Peter; Scott, Suzanne; Emptage, Nigel; Dholakia, Kishan

2016-01-01

Investigation of the transient processes integral to neuronal function demands rapid and high-resolution imaging techniques over a large field of view, which cannot be achieved with conventional scanning microscopes. Here we describe a compact light sheet fluorescence microscope, featuring a 45° inverted geometry and an integrated photolysis laser, that is optimized for applications in neuroscience, in particular fast imaging of sub-neuronal structures in mammalian brain slices. We demonstrate the utility of this design for three-dimensional morphological reconstruction, activation of a single synapse with localized photolysis, and fast imaging of neuronal Ca2+ signalling across a large field of view. The developed system opens up a host of novel applications for the neuroscience community. PMID:27215692

Fabrication and characterization of inverted organic solar cells using shuttle cock-type metal phthalocyanine and PCBM:P3HT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Furukawa, Ryo, E-mail: suzuki@mat.usp.ac.jp; Akiyama, Tsuyoshi, E-mail: suzuki@mat.usp.ac.jp

2015-02-27

Inverted organic solar cells using shuttle cock-type phthalocyanine, semiconducting polymer and fullerenes were fabricated and characterized. Photovoltaic and optical properties of the solar cells with inverted structures were investigated by optical absorption, current density-voltage characteristics. The photovoltaic properties of the tandem organic solar cell using titanyl phthalocyanine, vanadyl phthalocyanine, poly(3-hexylthiophene) (P3HT) and [6, 6]-phenyl C{sub 61}-butyric acid methyl ester (PCBM) were improved. Effect of annealing and solvent treatment on surface morphologies of the active layer was investigated. The photovoltaic mechanisms, energy levels and band gap of active layers were discussed for improvement of the photovoltaic performance.

Sol-gel derived ZnO as an electron transport layer (ETL) for inverted organic solar cells

NASA Astrophysics Data System (ADS)

Tiwari, D. C.; Dwivedi, Shailendra Kumar; Dipak, Phukhrambam; Chandel, Tarun; Sharma, Rishi

2017-05-01

In this work, we present the study of the fabrication process of the sol-gel derived zinc oxide (ZnO) as an electron transport layer (ETL.). The solution processed inverted bulk heterojunction organic solar cells based on a thin film blend of poly (3-hexylthiophene 2, 5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester is prepared. ZnO thin films are annealed at different temperature to optimize the solar cell performance and their characterization for their structural and optical properties are carried out. We have observed Voc=70mV, Jsc=1.33 µA/cm2 and FF=26% from the inverted heterojunction solar cell.

Deciphering the internal complexity of living cells with quantitative phase microscopy: a multiscale approach

NASA Astrophysics Data System (ADS)

Martinez-Torres, Cristina; Laperrousaz, Bastien; Berguiga, Lotfi; Boyer-Provera, Elise; Elezgaray, Juan; Nicolini, Franck E.; Maguer-Satta, Veronique; Arneodo, Alain; Argoul, Françoise

2015-09-01

The distribution of refractive indices (RIs) of a living cell contributes in a nonintuitive manner to its optical phase image and quite rarely can be inverted to recover its internal structure. The interpretation of the quantitative phase images of living cells remains a difficult task because (1) we still have very little knowledge on the impact of its internal macromolecular complexes on the local RI and (2) phase changes produced by light propagation through the sample are mixed with diffraction effects by the internal cell bodies. We propose to implement a two-dimensional wavelet-based contour chain detection method to distinguish internal boundaries based on their greatest optical path difference gradients. These contour chains correspond to the highest image phase contrast and follow the local RI inhomogeneities linked to the intracellular structural intricacy. Their statistics and spatial distribution are the morphological indicators suited for comparing cells of different origins and/or to follow their transformation in pathologic situations. We use this method to compare nonadherent blood cells from primary and laboratory culture origins and to assess the internal transformation of hematopoietic stem cells by the transduction of the BCR-ABL oncogene responsible for the chronic myelogenous leukemia.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Syracuse, E. M.; Maceira, M.; Zhang, H.

Joint inversions of seismic data recover models that simultaneously fit multiple constraints while playing upon the strengths of each data type. Here, we jointly invert 14 years of local earthquake body wave arrival times from the Alaska Volcano Observatory catalog and Rayleigh wave dispersion curves based upon ambient noise measurements for local V p, V s, and hypocentral locations at Akutan and Makushin Volcanoes using a new joint inversion algorithm.The velocity structure and relocated seismicity of both volcanoes are significantly more complex than many other volcanoes studied using similar techniques. Seismicity is distributed among several areas beneath or beyond themore » flanks of both volcanoes, illuminating a variety of volcanic and tectonic features. The velocity structures of the two volcanoes are exemplified by the presence of narrow high-V p features in the near surface, indicating likely current or remnant pathways of magma to the surface. A single broad low-V p region beneath each volcano is slightly offset from each summit and centered at approximately 7 km depth, indicating a potential magma chamber, where magma is stored over longer time periods. Differing recovery capabilities of the Vp and Vs datasets indicate that the results of these types of joint inversions must be interpreted carefully.« less

Structure and Function of Na+-Symporters with Inverted Repeats

PubMed Central

Abramson, Jeff; Wright, Ernest M.

2009-01-01

Summary Symporters are membrane proteins that couple energy stored in electrochemical potential gradients to drive the cotransport of molecules and ions into cells. Traditionally, proteins are classified into gene families based on sequence homology and functional properties, e.g. the sodium glucose (SLC5 or Sodium Solute Symporter Family, SSS or SSF) and GABA (SLC6 or Neurotransmitter Sodium Symporter Family, NSS or SNF) symporter families [1-4]. Recently, it has been established that four Na+-symporter proteins with unrelated sequences have a common structural core containing an inverted repeat of 5 transmembrane (TM) helices [5-8]. Analysis of these four structures reveals that they reside in different conformations along the transport cycle providing atomic insight into the mechanism of sodium solute cotransport. PMID:19631523

WSJointInv2D-MT-DCR: An efficient joint two-dimensional magnetotelluric and direct current resistivity inversion

NASA Astrophysics Data System (ADS)

Amatyakul, Puwis; Vachiratienchai, Chatchai; Siripunvaraporn, Weerachai

2017-05-01

An efficient joint two-dimensional direct current resistivity (DCR) and magnetotelluric (MT) inversion, referred to as WSJointInv2D-MT-DCR, was developed with FORTRAN 95 based on the data space Occam's inversion algorithm. Our joint inversion software can be used to invert just the MT data or the DCR data, or invert both data sets simultaneously to get the electrical resistivity structures. Since both MT and DCR surveys yield the same resistivity structures, the two data types enhance each other leading to a better interpretation. Two synthetic and a real field survey are used here to demonstrate that the joint DCR and MT surveys can help constrain each other to reduce the ambiguities occurring when inverting the DCR or MT alone. The DCR data increases the lateral resolution of the near surface structures while the MT data reveals the deeper structures. When the MT apparent resistivity suffers from the static shift, the DCR apparent resistivity can serve as a replacement for the estimation of the static shift factor using the joint inversion. In addition, we also used these examples to show the efficiency of our joint inversion code. With the availability of our new joint inversion software, we expect the number of joint DCR and MT surveys to increase in the future.

Coupled Leidenfrost states as a monodisperse granular clock

NASA Astrophysics Data System (ADS)

Liu, Rui; Yang, Mingcheng; Chen, Ke; Hou, Meiying; To, Kiwing

2016-08-01

Using an event-driven molecular dynamics simulation, we show that simple monodisperse granular beads confined in coupled columns may oscillate as a different type of granular clock. To trigger this oscillation, the system needs to be driven against gravity into a density-inverted state, with a high-density clustering phase supported from below by a gaslike low-density phase (Leidenfrost effect) in each column. Our analysis reveals that the density-inverted structure and the relaxation dynamics between the phases can amplify any small asymmetry between the columns, and lead to a giant oscillation. The oscillation occurs only for an intermediate range of the coupling strength, and the corresponding phase diagram can be universally described with a characteristic height of the density-inverted structure. A minimal two-phase model is proposed and a linear stability analysis shows that the triggering mechanism of the oscillation can be explained as a switchable two-parameter Andronov-Hopf bifurcation. Numerical solutions of the model also reproduce similar oscillatory dynamics to the simulation results.

Examining System-Wide Impacts of Solar PV Control Systems with a Power Hardware-in-the-Loop Platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Tess L.; Fuller, Jason C.; Schneider, Kevin P.

2014-06-08

High penetration levels of distributed solar PV power generation can lead to adverse power quality impacts, such as excessive voltage rise, voltage flicker, and reactive power values that result in unacceptable voltage levels. Advanced inverter control schemes have been developed that have the potential to mitigate many power quality concerns. However, local closed-loop control may lead to unintended behavior in deployed systems as complex interactions can occur between numerous operating devices. To enable the study of the performance of advanced control schemes in a detailed distribution system environment, a test platform has been developed that integrates Power Hardware-in-the-Loop (PHIL) withmore » concurrent time-series electric distribution system simulation. In the test platform, GridLAB-D, a distribution system simulation tool, runs a detailed simulation of a distribution feeder in real-time mode at the Pacific Northwest National Laboratory (PNNL) and supplies power system parameters at a point of common coupling. At the National Renewable Energy Laboratory (NREL), a hardware inverter interacts with grid and PV simulators emulating an operational distribution system. Power output from the inverters is measured and sent to PNNL to update the real-time distribution system simulation. The platform is described and initial test cases are presented. The platform is used to study the system-wide impacts and the interactions of inverter control modes—constant power factor and active Volt/VAr control—when integrated into a simulated IEEE 8500-node test feeder. We demonstrate that this platform is well-suited to the study of advanced inverter controls and their impacts on the power quality of a distribution feeder. Additionally, results are used to validate GridLAB-D simulations of advanced inverter controls.« less

Growth of high quality bulk size single crystals of inverted solubility lithium sulphate monohydrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silambarasan, A.; Rajesh, P., E-mail: rajeshp@ssn.edu.in; Ramasamy, P.

2015-06-24

The paper summarizes the processes of growing large lithium sulfate monohydrate (LSMH) single crystals. We have established a procedure to grow high quality bulk size single crystals of inverted solubility LSMH by a newly developed unidirectional crystallization technique called the Sankeranarayenan - Ramasamy (SR) method. The convective flow of crystal growth processes from solution and the conditions of growing crystals of various aspects were discussed. Good quality LSMH single crystal is grown of the size 20 mmX80 mm without cracks, localized-defects and inclusions. The as-grown crystals are suitable for piezoelectric and nonlinear optical applications.

Universality of bridge functions and its relation to variational perturbation theory and additivity of equations of state

NASA Astrophysics Data System (ADS)

Rosenfeld, Yaakov

1984-05-01

Featuring the modified hypernetted-chain (MHNC) scheme as a variational fitting procedure, we demonstrate that the accuracy of the variational perturbation theory (VPT) and of the method based on additivity of equations of state is determined by the excess entropy dependence of the bridge-function parameters [i.e., η(s) when the Percus-Yevick hard-sphere bridge functions are employed]. It is found that η(s) is nearly universal for all soft (i.e., "physical") potentials while it is distinctly different for the hard spheres, providing a graphical display of the "jump" in pair-potential space (with respect to accuracy of VPT) from "hard" to "soft" behavior. The universality of η(s) provides a local criterion for the MHNC scheme that should be useful for inverting structure-factor data in order to obtain the potential. An alternative local MHNC criterion due to Lado is rederived and extended, and it is also analyzed in light of the plot of η(s).

Origins of chemoreceptor curvature sorting in Escherichia coli

PubMed Central

Draper, Will; Liphardt, Jan

2017-01-01

Bacterial chemoreceptors organize into large clusters at the cell poles. Despite a wealth of structural and biochemical information on the system's components, it is not clear how chemoreceptor clusters are reliably targeted to the cell pole. Here, we quantify the curvature-dependent localization of chemoreceptors in live cells by artificially deforming growing cells of Escherichia coli in curved agar microchambers, and find that chemoreceptor cluster localization is highly sensitive to membrane curvature. Through analysis of multiple mutants, we conclude that curvature sensitivity is intrinsic to chemoreceptor trimers-of-dimers, and results from conformational entropy within the trimer-of-dimers geometry. We use the principles of the conformational entropy model to engineer curvature sensitivity into a series of multi-component synthetic protein complexes. When expressed in E. coli, the synthetic complexes form large polar clusters, and a complex with inverted geometry avoids the cell poles. This demonstrates the successful rational design of both polar and anti-polar clustering, and provides a synthetic platform on which to build new systems. PMID:28322223

Time development of high-altitude auroral acceleration region plasma, potentials, and field-aligned current systems observed by Cluster during a substorm

NASA Astrophysics Data System (ADS)

Hull, A. J.; Chaston, C. C.; Fillingim, M. O.; Mozer, F.; Frey, H. U.

2013-12-01

The auroral acceleration region is an integral link in the chain of events that transpire during substorms, and the currents, plasma and electric fields undergo significant changes driven by complex dynamical processes deep in the magnetotail. These auroral acceleration processes in turn accelerate and heat the plasma that ultimately leads to some of the most intense global substorm auroral displays. The complex interplay between field-aligned current system formation, the development of parallel electric fields, and resultant changes in the plasma constituents that occur during substorms within or just above the auroral acceleration zone remain unclear. We present Cluster multi-point observations within the high-altitude acceleration region (> 3 Re altitude) at key instances during the development of a substorm. Of particular emphasis is on the time-development of the plasma, potentials and currents that occur therein with the aim of ascertaining high-altitude drivers of substorm active auroral acceleration processes and auroral emission consequences. Preliminary results show that the initial onset is dominated by Alfvenic activity as evidenced by the sudden occurrence of relatively intense, short-spatial scale Alfvenic currents and attendant energy dispersed, counterstreaming electrons poleward of the growth-phase arc. The Alfvenic currents are locally planar structures with characteristic thicknesses on the order of a few tens of kilometers. In subsequent passages by the other spacecraft, the plasma sheet region became hotter and thicker via the injection of new hot, dense plasma of magnetospheric origins poleward of the pre-existing growth phase arc. In association with the heating and/or thickening of the plasma sheet, the currents appeared to broaden to larger scales as Alfven dominated activity gave way to either inverted-V dominated or mixed inverted-V and Alfvenic behavior depending on location. The transition from Alfven dominated to inverted-V dominated current systems was quite rapid, occurring in the span of a few minutes. These results suggest that the Alfvenic activity may be an important precursor and perhaps may be playing an essential role in the development of inverted-V arc systems that form during substorms.

Smart Inverter Control and Operation for Distributed Energy Resources

NASA Astrophysics Data System (ADS)

Tazay, Ahmad F.

The motivation of this research is to carry out the control and operation of smart inverters and voltage source converters (VSC) for distributed energy resources (DERs) such as photovoltaic (PV), battery, and plug-in hybrid electric vehicles (PHEV). The main contribution of the research includes solving a couple of issues for smart grids by controlling and implementing multifunctions of VSC and smart inverter as well as improving the operational scheme of the microgrid. The work is mainly focused on controlling and operating of smart inverter since it promises a new technology for the future microgrid. Two major applications of the smart inverter will be investigated in this work based on the connection modes: microgrid at grid-tied mode and autonomous mode. In grid-tied connection, the smart inverter and VSC are used to integrate DER such as Photovoltaic (PV) and battery to provide suitable power to the system by controlling the supplied real and reactive power. The role of a smart inverter at autonomous mode includes supplying a sufficient voltage and frequency, mitigate abnormal condition of the load as well as equally sharing the total load's power. However, the operational control of the microgrid still has a major issue on the operation of the microgrid. The dissertation is divided into two main sections which are: 1. Low-level control of a single smart Inverter. 2. High-level control of the microgrid. The first part investigates a comprehensive research for a smart inverter and VSC technology at the two major connections of the microgrid. This involves controlling and modeling single smart inverter and VSC to solve specific issues of microgrid as well as improve the operation of the system. The research provides developed features for smart inverter comparing with a conventional voltage sourced converter (VSC). The two main connections for a microgrid have been deeply investigated to analyze a better way to develop and improve the operational procedure of the microgrid as well as solve specific issues of connecting the microgrid to the system. A detailed procedure for controlling VSC and designing an optimal operation of the controller is also covered in the first part of the dissertation. This section provides an optimal operation for controlling motor drive and demonstrates issues when motor load exists at an autonomous microgrid. It also provides a solution for specific issues at operating a microgrid at autonomous mode as well as improving the structural design for the grid-tied microgrid. The solution for autonomous microgrid includes changing the operational state of the switching pattern of the smart inverter to solve the issue of a common mode voltage (CMV) that appears across the motor load. It also solves the issue of power supplying to large loads, such as induction motors. The last section of the low-level section involves an improvement of the performance and operation of the PV charging station for a plug-in hybrid electric vehicle (PHEV) at grid-tied mode. This section provides a novel structure and smart controller for PV charging station using three-phase hybrid boost converter topology. It also provides a form of applications of a multifunction smart inverter using PV charging station. The second part of the research is focusing on improving the performance of the microgrid by integrating several smart inverters to form a microgrid. It investigates the issue of connecting DER units with the microgrid at real applications. One of the common issues of the microgrid is the circulating current which is caused by poor reactive power sharing accuracy. When more than two DER units are connected in parallel, a microgrid is forming be generating required power for the load. When the microgrid is operated at autonomous mode, all DER units participate in generating voltage and frequency as well as share the load's power. This section provides a smart and novel controlling technique to solve the issue of unequal power sharing. The feature of the smart inverter is realized by the communication link between smart inverters and the main operator. The analysis and derivation of the problem are presented in this section. The dissertation has led to two accepted conference papers, one accepted transaction IEEE manuscript, and one submitted IET transaction manuscript. The future work aims to improve the current work by investigating the performance of the smart inverter at real applications.

Abnormalities in the Visual Processing of Viewing Complex Visual Stimuli Amongst Individuals With Body Image Concern.

PubMed

Duncum, A J F; Atkins, K J; Beilharz, F L; Mundy, M E

2016-01-01

Individuals with body dysmorphic disorder (BDD) and clinically concerning body-image concern (BIC) appear to possess abnormalities in the way they perceive visual information in the form of a bias towards local visual processing. As inversion interrupts normal global processing, forcing individuals to process locally, an upright-inverted stimulus discrimination task was used to investigate this phenomenon. We examined whether individuals with nonclinical, yet high levels of BIC would show signs of this bias, in the form of reduced inversion effects (i.e., increased local processing). Furthermore, we assessed whether this bias appeared for general visual stimuli or specifically for appearance-related stimuli, such as faces and bodies. Participants with high-BIC (n = 25) and low-BIC (n = 30) performed a stimulus discrimination task with upright and inverted faces, scenes, objects, and bodies. Unexpectedly, the high-BIC group showed an increased inversion effect compared to the low-BIC group, indicating perceptual abnormalities may not be present as local processing biases, as originally thought. There was no significant difference in performance across stimulus types, signifying that any visual processing abnormalities may be general rather than appearance-based. This has important implications for whether visual processing abnormalities are predisposing factors for BDD or develop throughout the disorder.

Topological mosaics in moiré superlattices of van der Waals heterobilayers

NASA Astrophysics Data System (ADS)

Tong, Qingjun; Yu, Hongyi; Zhu, Qizhong; Wang, Yong; Xu, Xiaodong; Yao, Wang

2017-04-01

Van der Waals (vdW) heterostructures formed by two-dimensional atomic crystals provide a powerful approach towards designer condensed matter systems. Incommensurate heterobilayers with small twisting and/or lattice mismatch lead to the interesting concept of moiré superlattices, where the atomic registry is locally indistinguishable from commensurate bilayers but has local-to-local variation over long range. Here we show that such moiré superlattices can lead to periodic modulation of local topological order in vdW heterobilayers formed by two massive Dirac materials. By tuning the vdW heterojunction from normal to the inverted type-II regime via an interlayer bias, the commensurate heterobilayer can become a topological insulator (TI), depending on the interlayer hybridization controlled by the atomic registry between the vdW layers. This results in a mosaic pattern of TI regions and normal insulator (NI) regions in moiré superlattices, where topologically protected helical modes exist at the TI/NI phase boundaries. By using symmetry-based k .p and tight-binding models, we predict that this topological phenomenon can be present in inverted transition metal dichalcogenides heterobilayers. Our work points to a new means of realizing programmable and electrically switchable topological superstructures from two-dimensional arrays of TI nano-dots to one-dimensional arrays of TI nano-stripes.

Vibrational Spectroscopy of BENZENE-(WATER)_N Clusters with N=6,7

NASA Astrophysics Data System (ADS)

Tabor, Daniel P.; Sibert, Edwin; Kusaka, Ryoji; Walsh, Patrick S.; Zwier, Timothy S.

2015-06-01

The investigation of benzene-water clusters (Bz-(H_2O)_n) provides insight into the relative importance π-hydrogen bond interactions in cluster formation. Taking advantage of the higher resolution of current IR sources, isomer-specific resonant ion-dip infrared (RIDIR) spectra were recorded in the OH stretch region (3000-3750 cm-1). A local mode Hamiltonian for describing the OH stretch vibrations of water clusters is applied to Bz-(H_2O)_6 and Bz-(H_2O)_7 and compared with the RIDIR spectra. These clusters are the smallest water clusters in which three-dimensional H-bonded networks containing three-coordinate water molecules begin to be formed, and are therefore particularly susceptible to re-ordering or re-shaping in response to the presence of a benzene molecule. The spectrum of Bz-(H_2O)_6 is assigned to an inverted book structure while the major conformer of Bz-(H_2O)_7 is assigned to an S_4-derived inserted cubic structure in which the benzene occupies one corner of the cube. The local mode model is used to extract monomer Hamiltonians for individual water molecules, including stretch-bend Fermi resonance and intra-monomer couplings. The monomer Hamiltonians divide into sub-groups based on their local H-bonding architecture (DA, DDA, DAA) and the nature of their interaction with benzene.

Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry

DOE PAGES

Ma, Eric Yue; Calvo, M. Reyes; Wang, Jing; ...

2015-05-26

The realization of quantum spin Hall effect in HgTe quantum wells is considered a milestone in the discovery of topological insulators. Quantum spin Hall states are predicted to allow current flow at the edges of an insulating bulk, as demonstrated in various experiments. A key prediction yet to be experimentally verified is the breakdown of the edge conduction under broken time-reversal symmetry. Here we first establish a systematic framework for the magnetic field dependence of electrostatically gated quantum spin Hall devices. We then study edge conduction of an inverted quantum well device under broken time-reversal symmetry using microwave impedance microscopy,more » and compare our findings to a non-inverted device. At zero magnetic field, only the inverted device shows clear edge conduction in its local conductivity profile, consistent with theory. Surprisingly, the edge conduction persists up to 9 T with little change. Finally, this indicates physics beyond simple quantum spin Hall model, including material-specific properties and possibly many-body effects.« less

Surface Plasmon Resonance Effect in Inverted Perovskite Solar Cells.

PubMed

Cui, Jin; Chen, Cheng; Han, Junbo; Cao, Kun; Zhang, Wenjun; Shen, Yan; Wang, Mingkui

2016-03-01

This work reports on incorporation of spectrally tuned gold/silica (Au/SiO 2 ) core/shell nanospheres and nanorods into the inverted perovskite solar cells (PVSC). The band gap of hybrid lead halide iodide (CH 3 NH 3 PbI 3 ) can be gradually increased by replacing iodide with increasing amounts of bromide, which can not only offer an appreciate solar radiation window for the surface plasmon resonance effect utilization, but also potentially result in a large open circuit voltage. The introduction of localized surface plasmons in CH 3 NH 3 PbI 2.85 Br 0.15 -based photovoltaic system, which occur in response to electromagnetic radiation, has shown dramatic enhancement of exciton dissociation. The synchronized improvement in photovoltage and photocurrent leads to an inverted CH 3 NH 3 PbI 2.85 Br 0.15 planar PVSC device with power conversion efficiency of 13.7%. The spectral response characterization, time resolved photoluminescence, and transient photovoltage decay measurements highlight the efficient and simple method for perovskite devices.

Uncovering Droop Control Laws Embedded Within the Nonlinear Dynamics of Van der Pol Oscillators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinha, Mohit; Dorfler, Florian; Johnson, Brian B.

This paper examines the dynamics of power-electronic inverters in islanded microgrids that are controlled to emulate the dynamics of Van der Pol oscillators. The general strategy of controlling inverters to emulate the behavior of nonlinear oscillators presents a compelling time-domain alternative to ubiquitous droop control methods which presume the existence of a quasistationary sinusoidal steady state and operate on phasor quantities. We present two main results in this paper. First, by leveraging the method of periodic averaging, we demonstrate that droop laws are intrinsically embedded within a slower time scale in the nonlinear dynamics of Van der Pol oscillators. Second,more » we establish the global convergence of amplitude and phase dynamics in a resistive network interconnecting inverters controlled as Van der Pol oscillators. Furthermore, under a set of nonrestrictive decoupling approximations, we derive sufficient conditions for local exponential stability of desirable equilibria of the linearized amplitude and phase dynamics.« less

Interaction between fault systems in a complex tectonic setting: Insights from InSAR and Teleseismic analysis of the 2015 Lake Saurez and 2016 Muji fault earthquake sequence

NASA Astrophysics Data System (ADS)

Nanjundiah, P.; Barbot, S.; Wei, S.; Tapponnier, P.; Feng, W.; Wang, T.

2017-12-01

The Pamir Plateau is a complex and important component of the India-Eurasia Collision zone. Despite being similar to the Tibetan plateau in elevation and collision processes, quite a bit is still unknown about the structure and the tectonic processes occurring in this region. We aim to better understand the structure, stress and deformation patterns in the northern and central Pamir plateau by analysing InSAR, teleseismic, and optical data for two large earthquakes that occurred in this region between December 2015 (Mw 7.2, Lake Saurez) and November 2016 (Mw 6.6 Muji Fault). We constrain the fault geometry by precisely relocating aftershocks using the double difference technique implemented in HypoDD (Waldhauser & Ellsworth 2000). We used Okada's (1992) Green Functions to invert for slip on the fault with a rectangular dislocation and edgreen to numerically invert for the slip in a layered medium (Wang et al. 2005). The combined datasets highlight the existence of an oblique fault between two major thrust fault systems i.e. the Darwas & the Karakoram faults. The December 2015 event highlights complexity in this fault system. The combination of data sets used in this study highlights the existence of a seismic gap south of Lake Karakul as well as coupling between the Muji and Darwas-Karakoram fault systems. We emphasise the role of smaller faults and their interactions in accommodating the overall strain and tectonics in the Pamir region and their effect on estimating local seismic hazard.

Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer

NASA Astrophysics Data System (ADS)

Xu, Wenya; Dou, Junyan; Zhao, Jianwen; Tan, Hongwei; Ye, Jun; Tange, Masayoshi; Gao, Wei; Xu, Weiwei; Zhang, Xiang; Guo, Wenrui; Ma, Changqi; Okazaki, Toshiya; Zhang, Kai; Cui, Zheng

2016-02-01

Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (+/-2 V) and subthreshold swing (SS) (122-161 mV dec-1), high effective mobility (up to 17.6-37.7 cm2 V-1 s-1) and high on/off ratio (104-107). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption.Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (+/-2 V) and subthreshold swing (SS) (122-161 mV dec-1), high effective mobility (up to 17.6-37.7 cm2 V-1 s-1) and high on/off ratio (104-107). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00015k

Parametrization of local CR automorphisms by finite jets and applications

NASA Astrophysics Data System (ADS)

Lamel, Bernhard; Mir, Nordine

2007-04-01

For any real-analytic hypersurface Msubset {C}^N , which does not contain any complex-analytic subvariety of positive dimension, we show that for every point pin M the local real-analytic CR automorphisms of M fixing p can be parametrized real-analytically by their ell_p jets at p . As a direct application, we derive a Lie group structure for the topological group operatorname{Aut}(M,p) . Furthermore, we also show that the order ell_p of the jet space in which the group operatorname{Aut}(M,p) embeds can be chosen to depend upper-semicontinuously on p . As a first consequence, it follows that given any compact real-analytic hypersurface M in {C}^N , there exists an integer k depending only on M such that for every point pin M germs at p of CR diffeomorphisms mapping M into another real-analytic hypersurface in {C}^N are uniquely determined by their k -jet at that point. Another consequence is the following boundary version of H. Cartan's uniqueness theorem: given any bounded domain Ω with smooth real-analytic boundary, there exists an integer k depending only on partial Ω such that if H\\colon Ωto Ω is a proper holomorphic mapping extending smoothly up to partial Ω near some point pin partial Ω with the same k -jet at p with that of the identity mapping, then necessarily H=Id . Our parametrization theorem also holds for the stability group of any essentially finite minimal real-analytic CR manifold of arbitrary codimension. One of the new main tools developed in the paper, which may be of independent interest, is a parametrization theorem for invertible solutions of a certain kind of singular analytic equations, which roughly speaking consists of inverting certain families of parametrized maps with singularities.

Inverted papillomas of the nasal and paranasal sinuses that involve the ocular/adnexal region.

PubMed

Saldana, Manuel; Wearne, Michael; Beigi, Bijan; Petrarca, Robert

2013-12-01

To review the management of inverted papillomas presenting to oculoplastic surgeons at three institutions and the outcomes of treatment. A retrospective review of medical notes of patients presenting with inverted papillomas that invaded the orbit during a 7-year period. In total, six Caucasian patients were identified, the mean age at presentation was 63 years. The presenting features were nasal blockage, epiphora, proptosis and medial canthal mass. Four were classed as Stage IV and two as Stage III disease. The sites of origin were the lateral wall of the nose, frontal sinus, ethmoidal sinus and lacrimal system. The lesions were radiologically homogenous tumours with variable degrees of nose, paranasal sinuses and orbital involvement. Four out of six had foci of malignant transformation (two with carcinoma in situ and two with invasive squamous cell carcinoma). All were treated with surgical excision and three with adjunctive radiotherapy. One patient needed orbital exentration and subsequently died from complications of the tumour bleeding. Inverted papillomas that invade the orbit are likely to be malignant and locally aggressive tumours. Early and wide surgical excision provides the best chance of removal and minimises recurrence. Radiotherapy may be a useful adjunct. Following surgical intervention, all cases require long term observation to ensure tumour control.

The inverted pendulum model of bipedal standing cannot be stabilized through direct feedback of force and contractile element length and velocity at realistic series elastic element stiffness.

PubMed

van Soest, A J Knoek; Rozendaal, Leonard A

2008-07-01

Control of bipedal standing is typically analyzed in the context of a single-segment inverted pendulum model. The stiffness K (SE) of the series elastic element that transmits the force generated by the contractile elements of the ankle plantarflexors to the skeletal system has been reported to be smaller in magnitude than the destabilizing gravitational stiffness K ( g ). In this study, we assess, in case K (SE) + K ( g ) < 0, if bipedal standing can be locally stable under direct feedback of contractile element length, contractile element velocity (both sensed by muscle spindles) and muscle force (sensed by Golgi tendon organs) to alpha-motoneuron activity. A theoretical analysis reveals that even though positive feedback of force may increase the stiffness of the muscle-tendon complex to values well over the destabilizing gravitational stiffness, dynamic instability makes it impossible to obtain locally stable standing under the conditions assumed.

Tomographic imaging of Central Java, Indonesia: Preliminary result of joint inversion of the MERAMEX and MCGA earthquake data

NASA Astrophysics Data System (ADS)

Rohadi, Supriyanto; Widiyantoro, Sri; Nugraha, Andri Dian; Masturyono

2013-09-01

The realization of local earthquake tomography is usually conducted by removing distant events outside the study region, because these events may increase errors. In this study, tomographic inversion has been conducted using the travel time data of local and regional events in order to improve the structural resolution, especially for deep structures. We used the local MERapi Amphibious EXperiments (MERAMEX) data catalog that consists of 292 events from May to October 2004. The additional new data of regional events in the Java region were taken from the Meteorological, Climatological, and Geophysical Agency (MCGA) of Indonesia, which consist of 882 events, having at least 10 recording phases at each seismographic station from April 2009 to February 2011. We have conducted joint inversions of the combined data sets using double-difference tomography to invert for velocity structures and to conduct hypocenter relocation simultaneously. The checkerboard test results of Vp and Vs structures demonstrate a significantly improved spatial resolution from the shallow crust down to a depth of 165 km. Our tomographic inversions reveal a low velocity anomaly beneath the Lawu - Merapi zone, which is consistent with the results from previous studies. A strong velocity anomaly zone with low Vp, low Vs and low Vp/Vs is also identified between Cilacap and Banyumas. We interpret this anomaly as a fluid content material with large aspect ratio or sediment layer. This anomaly zone is in a good agreement with the existence of a large dome containing sediment in this area as proposed by previous geological studies. A low velocity anomaly zone is also detected in Kebumen, where it may be related to the extensional oceanic basin toward the land.

Joint Inversion of Phase and Amplitude Data of Surface Waves for North American Upper Mantle

NASA Astrophysics Data System (ADS)

Hamada, K.; Yoshizawa, K.

2015-12-01

For the reconstruction of the laterally heterogeneous upper-mantle structure using surface waves, we generally use phase delay information of seismograms, which represents the average phase velocity perturbation along a ray path, while the amplitude information has been rarely used in the velocity mapping. Amplitude anomalies of surface waves contain a variety of information such as anelastic attenuation, elastic focusing/defocusing, geometrical spreading, and receiver effects. The effects of elastic focusing/defocusing are dependent on the second derivative of phase velocity across the ray path, and thus, are sensitive to shorter-wavelength structure than the conventional phase data. Therefore, suitably-corrected amplitude data of surface waves can be useful for improving the lateral resolution of phase velocity models. In this study, we collect a large-number of inter-station phase velocity and amplitude ratio data for fundamental-mode surface waves with a non-linear waveform fitting between two stations of USArray. The measured inter-station phase velocity and amplitude ratios are then inverted simultaneously for phase velocity maps and local amplification factor at receiver locations in North America. The synthetic experiments suggest that, while the phase velocity maps derived from phase data only reflect large-scale tectonic features, those from phase and amplitude data tend to exhibit better recovery of the strength of velocity perturbations, which emphasizes local-scale tectonic features with larger lateral velocity gradients; e.g., slow anomalies in Snake River Plain and Rio Grande Rift, where significant local amplification due to elastic focusing are observed. Also, the spatial distribution of receiver amplification factor shows a clear correlation with the velocity structure. Our results indicate that inter-station amplitude-ratio data can be of help in reconstructing shorter-wavelength structures of the upper mantle.

Tomographic imaging of Central Java, Indonesia: Preliminary result of joint inversion of the MERAMEX and MCGA earthquake data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rohadi, Supriyanto; Widiyantoro, Sri; Nugraha, Andri Dian

The realization of local earthquake tomography is usually conducted by removing distant events outside the study region, because these events may increase errors. In this study, tomographic inversion has been conducted using the travel time data of local and regional events in order to improve the structural resolution, especially for deep structures. We used the local MERapi Amphibious EXperiments (MERAMEX) data catalog that consists of 292 events from May to October 2004. The additional new data of regional events in the Java region were taken from the Meteorological, Climatological, and Geophysical Agency (MCGA) of Indonesia, which consist of 882 events,more » having at least 10 recording phases at each seismographic station from April 2009 to February 2011. We have conducted joint inversions of the combined data sets using double-difference tomography to invert for velocity structures and to conduct hypocenter relocation simultaneously. The checkerboard test results of Vp and Vs structures demonstrate a significantly improved spatial resolution from the shallow crust down to a depth of 165 km. Our tomographic inversions reveal a low velocity anomaly beneath the Lawu - Merapi zone, which is consistent with the results from previous studies. A strong velocity anomaly zone with low Vp, low Vs and low Vp/Vs is also identified between Cilacap and Banyumas. We interpret this anomaly as a fluid content material with large aspect ratio or sediment layer. This anomaly zone is in a good agreement with the existence of a large dome containing sediment in this area as proposed by previous geological studies. A low velocity anomaly zone is also detected in Kebumen, where it may be related to the extensional oceanic basin toward the land.« less

Effects of epitaxial structure and processing on electrical characteristics of InAs-based nBn infrared detectors

NASA Astrophysics Data System (ADS)

Du, X.; Savich, G. R.; Marozas, B. T.; Wicks, G. W.

2017-02-01

The conventional processing of the III-V nBn photodetectors defines mesa devices by etching the contact n-layer and stopping immediately above the barrier, i.e., a shallow etch. This processing enables great suppression of surface leakage currents without having to explore surface passivation techniques. However, devices that are made with this processing scheme are subject to lateral diffusion currents. To address the lateral diffusion current, we compare the effects of different processing approaches and epitaxial structures of nBn detectors. The conventional solution for eliminating lateral diffusion current, a deep etch through the barrier and the absorber, creates increased dark currents and an increased device failure rate. To avoid deep etch processing, a new device structure is proposed, the inverted-nBn structure. By comparing with the conventional nBn structure, the results show that the lateral diffusion current is effectively eliminated in the inverted-nBn structure without elevating the dark currents.

On high-latitude convection field inhomogeneities, parallel electric fields and inverted-V precipitation events

NASA Technical Reports Server (NTRS)

Lennartsson, W.

1977-01-01

A simple model of a static electric field with a component parallel to the magnetic field is proposed for calculating the electric field and current distributions at various altitudes when the horizontal distribution of the convection electric field is given at a certain altitude above the auroral ionosphere. The model is shown to be compatible with satellite observations of inverted-V electron precipitation structures and associated irregularities in the convection electric field.

Power supply of autonomous systems using solar modules

NASA Astrophysics Data System (ADS)

Yurchenko, A. V.; Zotov, L. G.; Mekhtiev, A. D.; Yugai, V. V.; Tatkeeva, G. G.

2015-04-01

The article shows the methods of constructing autonomous decentralized energy systems from solar modules. It shows the operation of up DC inverter. It demonstrates the effectiveness of DC inverters with varying structure. The system has high efficiency and low level of conductive impulse noise and at the same time the system is practically feasible. Electrical processes have been analyzed to determine the characteristics of operating modes of the main circuit elements. Recommendations on using the converters have been given.

Computer-aided diagnosis of mammographic masses using geometric verification-based image retrieval

NASA Astrophysics Data System (ADS)

Li, Qingliang; Shi, Weili; Yang, Huamin; Zhang, Huimao; Li, Guoxin; Chen, Tao; Mori, Kensaku; Jiang, Zhengang

2017-03-01

Computer-Aided Diagnosis of masses in mammograms is an important indicator of breast cancer. The use of retrieval systems in breast examination is increasing gradually. In this respect, the method of exploiting the vocabulary tree framework and the inverted file in the mammographic masse retrieval have been proved high accuracy and excellent scalability. However it just considered the features in each image as a visual word and had ignored the spatial configurations of features. It greatly affect the retrieval performance. To overcome this drawback, we introduce the geometric verification method to retrieval in mammographic masses. First of all, we obtain corresponding match features based on the vocabulary tree framework and the inverted file. After that, we grasps the main point of local similarity characteristic of deformations in the local regions by constructing the circle regions of corresponding pairs. Meanwhile we segment the circle to express the geometric relationship of local matches in the area and generate the spatial encoding strictly. Finally we judge whether the matched features are correct or not, based on verifying the all spatial encoding are whether satisfied the geometric consistency. Experiments show the promising results of our approach.

Structure and molecular mechanism of a nucleobase-cation-symport-1 family transporter.

PubMed

Weyand, Simone; Shimamura, Tatsuro; Yajima, Shunsuke; Suzuki, Shun'ichi; Mirza, Osman; Krusong, Kuakarun; Carpenter, Elisabeth P; Rutherford, Nicholas G; Hadden, Jonathan M; O'Reilly, John; Ma, Pikyee; Saidijam, Massoud; Patching, Simon G; Hope, Ryan J; Norbertczak, Halina T; Roach, Peter C J; Iwata, So; Henderson, Peter J F; Cameron, Alexander D

2008-10-31

The nucleobase-cation-symport-1 (NCS1) transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85-angstrom resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 transmembrane helices, 10 of which are arranged in two inverted repeats of five helices. The structures of the outward-facing open and substrate-bound occluded conformations were solved, showing how the outward-facing cavity closes upon binding of substrate. Comparisons with the leucine transporter LeuT(Aa) and the galactose transporter vSGLT reveal that the outward- and inward-facing cavities are symmetrically arranged on opposite sides of the membrane. The reciprocal opening and closing of these cavities is synchronized by the inverted repeat helices 3 and 8, providing the structural basis of the alternating access model for membrane transport.

Fabrication of lateral lattice-polarity-inverted GaN heterostructure

NASA Astrophysics Data System (ADS)

Katayama, Ryuji; Kuge, Yoshihiro; Kondo, Takashi; Onabe, Kentaro

2007-04-01

Fabrication of the lateral polarity-inverted GaN heterostructure on sapphire (0 0 0 1) using a radio-frequency plasma enhanced molecular beam epitaxy is demonstrated. Its microscopic properties, which are closely related to the local polarity distribution, such as surface potentials, piezoelectric polarizations and residual carrier concentrations were investigated by Kelvin force microscopy and micro-Raman scattering. The successful inversion from Ga-polarity to N-polarity of GaN in a specific domain and its higher crystal perfection had been confirmed clearly by these microscopic analyses. The results were also fairly consistent with that of KOH etching experiments, which suggest the applicability of these processes to the fabrication of photonic nanostructures composed of nitride semiconductors.

Mount Etna: 3-D and 4-D structure using seismic tomography

NASA Astrophysics Data System (ADS)

Nunn, C.; Julian, B. R.; Foulger, G. R.; Patanè, D.; Ibáñez, J. M.; Briole, P.; Mhanna, N.

2015-12-01

We investigate the time-varying structure of Etna, an active stratovolcano in eastern Sicily, using seismic tomography. In volcanic systems, it is thought that the presence of fluids, cracks and pressurized gases can rapidly and drastically change the elastic properties of the host rocks. Recent work suggests that changes beneath Etna are detectable with seismic methods, and that these changes can be linked to volcanic activity. Temporal changes to Earth structure are commonly investigated by carrying out separate tomographic inversions for different epochs. However, repeated inversions of the same area are expected to vary, even if the structure itself does not change. This is due to variations in the seismic ray distribution and to observational errors. Potentially, changes between epochs which are due to experimental limitations can be misinterpreted as changes to the structure of the volcano. Consequently, we use a new tomographic program, TOMO4D, that inverts multiple data sets simultaneously [Julian & Foulger, Time-dependent seismic tomography, GJI, 2010]. This code imposes constraints which minimise the differences calculated between two epochs. The remaining structural variations are thus truly required to fit the data, and reflect changes which almost certainly exist between the two epochs. We have selected and relocated ~400 local earthquakes with at least 5 P and 5 S observations. They cover a period which includes several eruptions, from 1st November 2000 to 31st December 2006. We divide our data into different epochs and invert two epochs simultaneously. The models show a seismically fast central region, surrounded by a slower outer region. This suggests a central system of dykes or sills surrounded by volcanic sediments and country rock. At depths of 0-4 km below sea level the seismically fast region is not below the summit crater but is offset to the southwest. By monitoring the changes to the elastic parameters of the host rocks we observe temporal changes within the volcano. The technique has potential for long-term volcano monitoring and hazard assessment since it could be applied to monitoring changes from month to month.

Inverted cucurbit[6]uril supramolecular assemblies formed in the presence of tetrachlorozincate anions

NASA Astrophysics Data System (ADS)

Chen, Kai; Xu, Jing; Qiu, Sheng-Chao; Wang, Yuan; Chen, Min-Dong; Zhang, Yun-Qian; Xiao, Xin; Tao, Zhu

2017-10-01

We investigated the interactions in an inverted cucurbit[6]uril (iQ[6]) with a series of 1,ω-alkyldimins and their supramolecular assemblies in the presence of the tetrachlorozincate anion ([ZnCl4]2-) structure directing agent. iQ[6] forms an outer surface interaction with [ZnCl4]2- to form different iQ[6]/[ZnCl4]2--based supramolecular assemblies with different length 1,ω-alkyldimins. Interestingly, most 1,ω-alkyldimins were not visible in crystals structures in the presence of concentrated HCl. The porous iQ[6]/[ZnCl4]2--based supramolecular assemblies could be used as materials for adsorbing volatile compounds.

New lipid family that forms inverted cubic phases in equilibrium with excess water: molecular structure-aqueous phase structure relationship for lipids with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains.

PubMed

Yamashita, Jun; Shiono, Manzo; Hato, Masakatsu

2008-10-02

With a view to discovering a new family of lipids that form inverted cubic phases, the aqueous phase behavior of a series of lipids with isoprenoid-type hydrophobic chains has been examined over a temperature range from -40 to 65 degrees C by using optical microscopy, DSC (differential scanning calorimetry), and SAXS (small-angle X-ray scattering) techniques. The lipids examined are those with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains linked to a series of headgroups, that is, erythritol, pentaerythritol, xylose, and glucose. All of the lipid/water systems displayed a "water + liquid crystalline phase" two-phase coexistence state when sufficiently diluted. The aqueous phase structures of the most diluted liquid crystalline phases in equilibrium with excess water depend both on the lipid molecular structure and on the temperature. Given an isoprenoid chain, the preferred phase consistently follows a phase sequence of an H II (an inverted hexagonal phase) to a Q II (an inverted bicontinuous cubic phase) to an L alpha (a lamellar phase) as A* (cross-section area of the headgroup) increases. For a given lipid/water system, the phase sequence observed as the temperature increases is L alpha to Q II to H II. The present study allowed us to find four cubic phase-forming lipid species, PEOC 18+4 [mono- O-(5,9,13,17-tetramethyloctadecyl)pentaerythritol], beta-XylOC 18+4 [1- O-(5,9,13,17-tetramethyloctadecyl)-beta- d-xylopyranoside], EROCOC 17+4 [1- O-(5,9,13,17-tetramethyloctadecanoyl)erythritol], and PEOCOC 17+4 [mono- O-(5,9,13,17-tetramethyloctadecanoyl)pentaerythritol]. The values of T K (hydrated solid-liquid crystalline phase transition temperature) of the cubic phase-forming lipids are all below 0 degrees C. Quantitative analyses of the lipid molecular structure-aqueous phase structure relationship in terms of the experimentally evaluated "surfactant parameter" allow us to rationally select an optimum combination of hydrophilic/hydrophobic part of a lipid molecule that will form a desired phase in a desired temperature range.

Ion distribution effects of turbulence on a kinetic auroral arc model

NASA Technical Reports Server (NTRS)

Cornwall, J. M.; Chiu, Y. T.

1982-01-01

An inverted-V auroral arc structure plasma-kinetic model is extended to phenomenologically include the effects of electrostatic turbulence, with k-parallel/k-perpendicular being much less than unity. It is shown that, unless plasma sheet ions are very much more energetic than the electrons, anomalous resistivity is not a large contributor to parallel electrostatic potential drops, since the support of the observed potential drop requires a greater dissipation of energy than can be provided by the plasma sheet. Wave turbulence can, however, be present, with the ion cyclotron turbulence levels suggested by the ion resonance broadening saturation mechanism of Dum and Dupree (1970) being comparable to those observed on auroral field lines. The diffusion coefficient and net growth rate are much smaller than estimates based solely on local plasma properties.

Genome Cyclization as Strategy for Flavivirus RNA Replication

PubMed Central

Villordo, Sergio M.; Gamarnik, Andrea V.

2017-01-01

Long-range and local RNA-RNA contacts in viral RNA genomes result in tertiary structures that modulate the function of enhancers, promoters, and silencers during translation, RNA replication, and encapsidation. In the case of flaviviruses, the presence of inverted complementary sequences at the 5′ and 3′ ends of the genome mediate long-range RNA interactions and RNA cyclization. The circular conformation of flavivirus genomes was demonstrated to be essential for RNA amplification. New ideas about the mechanisms by which circular genomes participate in flavivirus replication have emerged in the last few years. Here, we will describe the latest information about cis-acting elements involved in flavivirus genome cyclization, RNA promoter elements required for viral polymerase recognition, and how these elements together coordinate viral RNA synthesis. PMID:18703097

Surface-enhanced Raman scattering on periodic metal nanotips with tunable sharpness.

PubMed

Linn, Nicholas C; Sun, Chih-Hung; Arya, Ajay; Jiang, Peng; Jiang, Bin

2009-06-03

This paper reports on a scalable bottom-up technology for producing periodic gold nanotips with tunable sharpness as surface-enhanced Raman scattering (SERS) substrates. Inverted silicon pyramidal pits, which are templated from non-close-packed colloidal crystals prepared by a spin-coating technology, are used as structural templates to replicate arrays of polymer nanopyramids with nanoscale sharp tips. The deposition of a thin layer of gold on the polymer nanopyramids leads to the formation of SERS-active substrates with a high enhancement factor (up to 10(8)). The thickness of the deposited metal determines the sharpness of the nanotips and the resulting Raman enhancement factor. Finite-element electromagnetic modeling shows that the nanotips can significantly enhance the local electromagnetic field and the sharpness of nanotips greatly affects the SERS enhancement.

Station corrections for the Katmai Region Seismic Network

USGS Publications Warehouse

Searcy, Cheryl K.

2003-01-01

Most procedures for routinely locating earthquake hypocenters within a local network are constrained to using laterally homogeneous velocity models to represent the Earth's crustal velocity structure. As a result, earthquake location errors may arise due to actual lateral variations in the Earth's velocity structure. Station corrections can be used to compensate for heterogeneous velocity structure near individual stations (Douglas, 1967; Pujol, 1988). The HYPOELLIPSE program (Lahr, 1999) used by the Alaska Volcano Observatory (AVO) to locate earthquakes in Cook Inlet and the Aleutian Islands is a robust and efficient program that uses one-dimensional velocity models to determine hypocenters of local and regional earthquakes. This program does have the capability of utilizing station corrections within it's earthquake location proceedure. The velocity structures of Cook Inlet and Aleutian volcanoes very likely contain laterally varying heterogeneities. For this reason, the accuracy of earthquake locations in these areas will benefit from the determination and addition of station corrections. In this study, I determine corrections for each station in the Katmai region. The Katmai region is defined to lie between latitudes 57.5 degrees North and 59.00 degrees north and longitudes -154.00 and -156.00 (see Figure 1) and includes Mount Katmai, Novarupta, Mount Martin, Mount Mageik, Snowy Mountain, Mount Trident, and Mount Griggs volcanoes. Station corrections were determined using the computer program VELEST (Kissling, 1994). VELEST inverts arrival time data for one-dimensional velocity models and station corrections using a joint hypocenter determination technique. VELEST can also be used to locate single events.

Structural analysis of the Gachsar sub-zone in central Alborz range; constrain for inversion tectonics followed by the range transverse faulting

NASA Astrophysics Data System (ADS)

Yassaghi, A.; Naeimi, A.

2011-08-01

Analysis of the Gachsar structural sub-zone has been carried out to constrain structural evolution of the central Alborz range situated in the central Alpine Himalayan orogenic system. The sub-zone bounded by the northward-dipping Kandovan Fault to the north and the southward-dipping Taleghan Fault to the south is transversely cut by several sinistral faults. The Kandovan Fault that controls development of the Eocene rocks in its footwall from the Paleozoic-Mesozoic units in the fault hanging wall is interpreted as an inverted basin-bounding fault. Structural evidences include the presence of a thin-skinned imbricate thrust system propagated from a detachment zone that acts as a footwall shortcut thrust, development of large synclines in the fault footwall as well as back thrusts and pop-up structures on the fault hanging wall. Kinematics of the inverted Kandovan Fault and its accompanying structures constrain the N-S shortening direction proposed for the Alborz range until Late Miocene. The transverse sinistral faults that are in acute angle of 15° to a major magnetic lineament, which represents a basement fault, are interpreted to develop as synthetic Riedel shears on the cover sequences during reactivation of the basement fault. This overprinting of the transverse faults on the earlier inverted extensional fault occurs since the Late Miocene when the south Caspian basin block attained a SSW movement relative to the central Iran. Therefore, recent deformation in the range is a result of the basement transverse-fault reactivation.

Multi-clues image retrieval based on improved color invariants

NASA Astrophysics Data System (ADS)

Liu, Liu; Li, Jian-Xun

2012-05-01

At present, image retrieval has a great progress in indexing efficiency and memory usage, which mainly benefits from the utilization of the text retrieval technology, such as the bag-of-features (BOF) model and the inverted-file structure. Meanwhile, because the robust local feature invariants are selected to establish BOF, the retrieval precision of BOF is enhanced, especially when it is applied to a large-scale database. However, these local feature invariants mainly consider the geometric variance of the objects in the images, and thus the color information of the objects fails to be made use of. Because of the development of the information technology and Internet, the majority of our retrieval objects is color images. Therefore, retrieval performance can be further improved through proper utilization of the color information. We propose an improved method through analyzing the flaw of shadow-shading quasi-invariant. The response and performance of shadow-shading quasi-invariant for the object edge with the variance of lighting are enhanced. The color descriptors of the invariant regions are extracted and integrated into BOF based on the local feature. The robustness of the algorithm and the improvement of the performance are verified in the final experiments.

Bayesian prestack seismic inversion with a self-adaptive Huber-Markov random-field edge protection scheme

NASA Astrophysics Data System (ADS)

Tian, Yu-Kun; Zhou, Hui; Chen, Han-Ming; Zou, Ya-Ming; Guan, Shou-Jun

2013-12-01

Seismic inversion is a highly ill-posed problem, due to many factors such as the limited seismic frequency bandwidth and inappropriate forward modeling. To obtain a unique solution, some smoothing constraints, e.g., the Tikhonov regularization are usually applied. The Tikhonov method can maintain a global smooth solution, but cause a fuzzy structure edge. In this paper we use Huber-Markov random-field edge protection method in the procedure of inverting three parameters, P-velocity, S-velocity and density. The method can avoid blurring the structure edge and resist noise. For the parameter to be inverted, the Huber-Markov random-field constructs a neighborhood system, which further acts as the vertical and lateral constraints. We use a quadratic Huber edge penalty function within the layer to suppress noise and a linear one on the edges to avoid a fuzzy result. The effectiveness of our method is proved by inverting the synthetic data without and with noises. The relationship between the adopted constraints and the inversion results is analyzed as well.

Robust sliding mode control applied to double Inverted pendulum system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahjoub, Sonia; Derbel, Nabil; Mnif, Faical

A three hierarchical sliding mode control is presented for a class of an underactuated system which can overcome the mismatched perturbations. The considered underactuated system is a double inverted pendulum (DIP), can be modeled by three subsystems. Such structure allows the construction of several designs of hierarchies for the controller. For all hierarchical designs, the asymptotic stability of every layer sliding mode surface and the sliding mode surface of subsystems are proved theoretically by Barbalat's lemma. Simulation results show the validity of these methods.

Efficient Broadband Terahertz Radiation Detectors Based on Bolometers with a Thin Metal Absorber

NASA Astrophysics Data System (ADS)

Dem'yanenko, M. A.

2018-01-01

The matrix method has been used to calculate the coefficients of absorption of terahertz radiation in conventional (with radiation incident from vacuum adjacent to the bolometer) and inverted (with radiation incident from the substrate on which the bolometer was fabricated) bolometric structures. Near-unity absorption coefficients were obtained when an additional cavity in the form of a gap between the bolometer and the input or output window was introduced. Conventional bolometers then became narrowband, while inverted-type devices remained broadband.

Functional inverted Wishart for Bayesian multivariate spatial modeling with application to regional climatology model data.

PubMed

Duan, L L; Szczesniak, R D; Wang, X

2017-11-01

Modern environmental and climatological studies produce multiple outcomes at high spatial resolutions. Multivariate spatial modeling is an established means to quantify cross-correlation among outcomes. However, existing models typically suffer from poor computational efficiency and lack the flexibility to simultaneously estimate auto- and cross-covariance structures. In this article, we undertake a novel construction of covariance by utilizing spectral convolution and by imposing an inverted Wishart prior on the cross-correlation structure. The cross-correlation structure with this functional inverted Wishart prior flexibly accommodates not only positive but also weak or negative associations among outcomes while preserving spatial resolution. Furthermore, the proposed model is computationally efficient and produces easily interpretable results, including the individual autocovariances and full cross-correlation matrices, as well as a partial cross-correlation matrix reflecting the outcome correlation after excluding the effects caused by spatial convolution. The model is examined using simulated data sets under different scenarios. It is also applied to the data from the North American Regional Climate Change Assessment Program, examining long-term associations between surface outcomes for air temperature, pressure, humidity, and radiation, on the land area of the North American West Coast. Results and predictive performance are compared with findings from approaches using convolution only or coregionalization.

Functional inverted Wishart for Bayesian multivariate spatial modeling with application to regional climatology model data

PubMed Central

Duan, L. L.; Szczesniak, R. D.; Wang, X.

2018-01-01

Modern environmental and climatological studies produce multiple outcomes at high spatial resolutions. Multivariate spatial modeling is an established means to quantify cross-correlation among outcomes. However, existing models typically suffer from poor computational efficiency and lack the flexibility to simultaneously estimate auto- and cross-covariance structures. In this article, we undertake a novel construction of covariance by utilizing spectral convolution and by imposing an inverted Wishart prior on the cross-correlation structure. The cross-correlation structure with this functional inverted Wishart prior flexibly accommodates not only positive but also weak or negative associations among outcomes while preserving spatial resolution. Furthermore, the proposed model is computationally efficient and produces easily interpretable results, including the individual autocovariances and full cross-correlation matrices, as well as a partial cross-correlation matrix reflecting the outcome correlation after excluding the effects caused by spatial convolution. The model is examined using simulated data sets under different scenarios. It is also applied to the data from the North American Regional Climate Change Assessment Program, examining long-term associations between surface outcomes for air temperature, pressure, humidity, and radiation, on the land area of the North American West Coast. Results and predictive performance are compared with findings from approaches using convolution only or coregionalization. PMID:29576735

Inversion by metalorganic chemical vapor deposition from N- to Ga-polar gallium nitride and its application to multiple quantum well light-emitting diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosalli, A. M.; Van Den Broeck, D. M.; Bedair, S. M.

2013-12-02

We demonstrate a metalorganic chemical vapor deposition growth approach for inverting N-polar to Ga-polar GaN by using a thin inversion layer grown with high Mg flux. The introduction of this inversion layer allowed us to grow p-GaN films on N-polar GaN thin film. We have studied the dependence of hole concentration, surface morphology, and degree of polarity inversion for the inverted Ga-polar surface on the thickness of the inversion layer. We then use this approach to grow a light emitting diode structure which has the MQW active region grown on the advantageous N-polar surface and the p-layer grown on themore » inverted Ga-polar surface.« less

Enhanced device performances of a new inverted top-emitting OLEDs with relatively thick Ag electrode.

PubMed

Park, So-Ra; Suh, Min Chul

2018-02-19

To improve the device performances of top-emitting organic light emitting diodes (TEOLEDs), we developed a new inverted TEOLEDs structure with silver (Ag) metal as a semi-transparent top electrode. Especially, we found that the use of relatively thick Ag electrode without using any carrier injection layer is beneficial to realize highly efficient device performances. Also, we could insert very thick overlying hole transport layer (HTL) on the emitting layer (EML) which could be very helpful to suppress the surface plasmon polariton (SPP) coupling if it is applied to the common bottom-emission OLEDs (BEOLEDs). As a result, we could realize noteworthy high current efficiency of approximately ~188.1 cd/A in our new inverted TEOLEDs with 25 nm thick Ag electrode.

Localized time-lapse elastic waveform inversion using wavefield injection and extrapolation: 2-D parametric studies

NASA Astrophysics Data System (ADS)

Yuan, Shihao; Fuji, Nobuaki; Singh, Satish; Borisov, Dmitry

2017-06-01

We present a methodology to invert seismic data for a localized area by combining source-side wavefield injection and receiver-side extrapolation method. Despite the high resolving power of seismic full waveform inversion, the computational cost for practical scale elastic or viscoelastic waveform inversion remains a heavy burden. This can be much more severe for time-lapse surveys, which require real-time seismic imaging on a daily or weekly basis. Besides, changes of the structure during time-lapse surveys are likely to occur in a small area rather than the whole region of seismic experiments, such as oil and gas reservoir or CO2 injection wells. We thus propose an approach that allows to image effectively and quantitatively the localized structure changes far deep from both source and receiver arrays. In our method, we perform both forward and back propagation only inside the target region. First, we look for the equivalent source expression enclosing the region of interest by using the wavefield injection method. Second, we extrapolate wavefield from physical receivers located near the Earth's surface or on the ocean bottom to an array of virtual receivers in the subsurface by using correlation-type representation theorem. In this study, we present various 2-D elastic numerical examples of the proposed method and quantitatively evaluate errors in obtained models, in comparison to those of conventional full-model inversions. The results show that the proposed localized waveform inversion is not only efficient and robust but also accurate even under the existence of errors in both initial models and observed data.

A state-of-the-art compact SiC photovoltaic inverter with maximum power point tracking function

NASA Astrophysics Data System (ADS)

Ando, Yuji; Oku, Takeo; Yasuda, Masashi; Ushijima, Kazufumi; Matsuo, Hiroshi; Murozono, Mikio

2018-01-01

We have developed a 150-W SiC-based photovoltaic (PV)-inverter with the maximum power point tracking (MPPT) function. The newly developed inverter achieved a state-of-the-art combination of the weight (0.79 kg) and the volume (790 mm3) as a 150-250 W class PV-inverter. As compared to the original version that we have previously reported, the weight and volume were decreased by 37% and 38%, respectively. This compactness originated from the optimized circuit structure and the increased density of a wiring circuit. Conversion efficiencies of the MPPT charge controller and the direct current (DC)-alternating current (AC) converter reached 96.4% and 87.6%, respectively. These efficiency values are comparable to those for the original version. We have developed a PV power generation system consisting of this inverter, a spherical Si solar cell module, and a 15-V Li-ion laminated battery. The total weight of the system was below 6 kg. The developed system exhibited stable output power characteristics, even when the weather conditions were fluctuated. These compactness, high efficiencies, and excellent stability clearly indicated the feasibility of SiC power devices even for sub-kW class PV power generation systems.

Resetting predator baselines in coral reef ecosystems

PubMed Central

Bradley, Darcy; Conklin, Eric; Papastamatiou, Yannis P.; McCauley, Douglas J.; Pollock, Kydd; Pollock, Amanda; Kendall, Bruce E.; Gaines, Steven D.; Caselle, Jennifer E.

2017-01-01

What did coral reef ecosystems look like before human impacts became pervasive? Early efforts to reconstruct baselines resulted in the controversial suggestion that pristine coral reefs have inverted trophic pyramids, with disproportionally large top predator biomass. The validity of the coral reef inverted trophic pyramid has been questioned, but until now, was not resolved empirically. We use data from an eight-year tag-recapture program with spatially explicit, capture-recapture models to re-examine the population size and density of a key top predator at Palmyra atoll, the same location that inspired the idea of inverted trophic biomass pyramids in coral reef ecosystems. Given that animal movement is suspected to have significantly biased early biomass estimates of highly mobile top predators, we focused our reassessment on the most mobile and most abundant predator at Palmyra, the grey reef shark (Carcharhinus amblyrhynchos). We estimated a density of 21.3 (95% CI 17.8, 24.7) grey reef sharks/km2, which is an order of magnitude lower than the estimates that suggested an inverted trophic pyramid. Our results indicate that the trophic structure of an unexploited reef fish community is not inverted, and that even healthy top predator populations may be considerably smaller, and more precarious, than previously thought. PMID:28220895

Multi-phase inversion tectonics related to the Hendijan-Nowrooz-Khafji Fault activity, Zagros Mountains, SW Iran

NASA Astrophysics Data System (ADS)

Kazem Shiroodi, Sadjad; Ghafoori, Mohammad; Faghih, Ali; Ghanadian, Mostafa; Lashkaripour, Gholamreza; Hafezi Moghadas, Naser

2015-11-01

Distinctive characteristics of inverted structures make them important criteria for the identification of certain structural styles of folded belts. The interpretation of 3D seismic reflection and well data sheds new light on the structural evolution and age of inverted structures associated to the Hendijan-Nowrooz-Khafji Fault within the Persian Gulf Basin and northeastern margin of Afro-Arabian plate. Analysis of thickness variations of growth strata using "T-Z plot" (thickness versus throw plot) method revealed the kinematics of the fault. Obtained results show that the fault has experienced a multi-phase evolutionary history over six different extension and compression deformation events (i.e. positive and negative inversion) between 252.2 and 11.62 Ma. This cyclic activity of the growth fault was resulted from alteration of sedimentary processes during continuous fault slip. The structural development of the study area both during positive and negative inversion geometry styles was ultimately controlled by the relative motion between the Afro-Arabian and Central-Iranian plates.

Retrieving Coherent Receiver Function Images with Dense Arrays

NASA Astrophysics Data System (ADS)

Zhong, M.; Zhan, Z.

2016-12-01

Receiver functions highlight converted phases (e.g., Ps, PpPs, sP) and have been widely used to study seismic interfaces. With a dense array, receiver functions (RFs) at multiple stations form a RF image that can provide more robust/detailed constraints. However, due to noise in data, non-uniqueness of deconvolution, and local structures that cannot be detected across neighboring stations, traditional RF images are often noisy and hard to interpret. Previous attempts to enhance coherence by stacking RFs from multiple events or post-filtering the RF images have not produced satisfactory improvements. Here, we propose a new method to retrieve coherent RF images with dense arrays. We take advantage of the waveform coherency at neighboring stations and invert for a small number of coherent arrivals for their RFs. The new RF images contain only the coherent arrivals required to fit data well. Synthetic tests and preliminary applications on real data demonstrate that the new RF images are easier to interpret and improve our ability to infer Earth structures using receiver functions.

A multi-frequency receiver function inversion approach for crustal velocity structure

NASA Astrophysics Data System (ADS)

Li, Xuelei; Li, Zhiwei; Hao, Tianyao; Wang, Sheng; Xing, Jian

2017-05-01

In order to constrain the crustal velocity structures better, we developed a new nonlinear inversion approach based on multi-frequency receiver function waveforms. With the global optimizing algorithm of Differential Evolution (DE), low-frequency receiver function waveforms can primarily constrain large-scale velocity structures, while high-frequency receiver function waveforms show the advantages in recovering small-scale velocity structures. Based on the synthetic tests with multi-frequency receiver function waveforms, the proposed approach can constrain both long- and short-wavelength characteristics of the crustal velocity structures simultaneously. Inversions with real data are also conducted for the seismic stations of KMNB in southeast China and HYB in Indian continent, where crustal structures have been well studied by former researchers. Comparisons of inverted velocity models from previous and our studies suggest good consistency, but better waveform fitness with fewer model parameters are achieved by our proposed approach. Comprehensive tests with synthetic and real data suggest that the proposed inversion approach with multi-frequency receiver function is effective and robust in inverting the crustal velocity structures.

Photovoltaic Impact Assessment of Smart Inverter Volt-VAR Control on Distribution System Conservation Voltage Reduction and Power Quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Fei; Nagarajan, Adarsh; Chakraborty, Sudipta

This report presents an impact assessment study of distributed photovoltaic (PV) with smart inverter Volt-VAR control on conservation voltage reduction (CVR) energy savings and distribution system power quality. CVR is a methodology of flattening and lowering a distribution system voltage profile in order to conserve energy. Traditional CVR relies on operating utility voltage regulators and switched capacitors. However, with the increased penetration of distributed PV systems, smart inverters provide the new opportunity to control local voltage and power factor by regulating the reactive power output, leading to a potential increase in CVR energy savings. This report proposes a methodology tomore » implement CVR scheme by operating voltage regulators, capacitors, and autonomous smart inverter Volt-VAR control in order to achieve increased CVR benefit. Power quality is an important consideration when operating a distribution system, especially when implementing CVR. It is easy to measure the individual components that make up power quality, but a comprehensive method to incorporate all of these values into a single score has yet to be undertaken. As a result, this report proposes a power quality scoring mechanism to measure the relative power quality of distribution systems using a single number, which is aptly named the 'power quality score' (PQS). Both the CVR and PQS methodologies were applied to two distribution system models, one obtained from the Hawaiian Electric Company (HECO) and another obtained from Pacific Gas and Electric (PG&E). These two models were converted to the OpenDSS platform using previous model conversion tools that were developed by NREL. Multiple scenarios including various PV penetration levels and smart inverter densities were simulated to analyze the impact of smart inverter Volt-VAR support on CVR energy savings and feeder power quality. In order to analyze the CVR benefit and PQS, an annual simulation was conducted for each scenario.« less

Why do electricity policy and competitive markets fail to use advanced PV systems to improve distribution power quality?

DOE Office of Scientific and Technical Information (OSTI.GOV)

McHenry, Mark P.; Johnson, Jay; Hightower, Mike

The increasing pressure for network operators to meet distribution network power quality standards with increasing peak loads, renewable energy targets, and advances in automated distributed power electronics and communications is forcing policy-makers to understand new means to distribute costs and benefits within electricity markets. Discussions surrounding how distributed generation (DG) exhibits active voltage regulation and power factor/reactive power control and other power quality capabilities are complicated by uncertainties of baseline local distribution network power quality and to whom and how costs and benefits of improved electricity infrastructure will be allocated. DG providing ancillary services that dynamically respond to the networkmore » characteristics could lead to major network improvements. With proper market structures renewable energy systems could greatly improve power quality on distribution systems with nearly no additional cost to the grid operators. Renewable DG does have variability challenges, though this issue can be overcome with energy storage, forecasting, and advanced inverter functionality. This paper presents real data from a large-scale grid-connected PV array with large-scale storage and explores effective mitigation measures for PV system variability. As a result, we discuss useful inverter technical knowledge for policy-makers to mitigate ongoing inflation of electricity network tariff components by new DG interconnection requirements or electricity markets which value power quality and control.« less

Why do electricity policy and competitive markets fail to use advanced PV systems to improve distribution power quality?

DOE PAGES

McHenry, Mark P.; Johnson, Jay; Hightower, Mike

2016-01-01

The increasing pressure for network operators to meet distribution network power quality standards with increasing peak loads, renewable energy targets, and advances in automated distributed power electronics and communications is forcing policy-makers to understand new means to distribute costs and benefits within electricity markets. Discussions surrounding how distributed generation (DG) exhibits active voltage regulation and power factor/reactive power control and other power quality capabilities are complicated by uncertainties of baseline local distribution network power quality and to whom and how costs and benefits of improved electricity infrastructure will be allocated. DG providing ancillary services that dynamically respond to the networkmore » characteristics could lead to major network improvements. With proper market structures renewable energy systems could greatly improve power quality on distribution systems with nearly no additional cost to the grid operators. Renewable DG does have variability challenges, though this issue can be overcome with energy storage, forecasting, and advanced inverter functionality. This paper presents real data from a large-scale grid-connected PV array with large-scale storage and explores effective mitigation measures for PV system variability. As a result, we discuss useful inverter technical knowledge for policy-makers to mitigate ongoing inflation of electricity network tariff components by new DG interconnection requirements or electricity markets which value power quality and control.« less

Interfacial Energy Alignment at the ITO/Ultra-Thin Electron Selective Dielectric Layer Interface and Its Effect on the Efficiency of Bulk-Heterojunction Organic Solar Cells.

PubMed

Itoh, Eiji; Goto, Yoshinori; Saka, Yusuke; Fukuda, Katsutoshi

2016-04-01

We have investigated the photovoltaic properties of an inverted bulk heterojunction (BHJ) cell in a device with an indium-tin-oxide (ITO)/electron selective layer (ESL)/P3HT:PCBM active layer/MoOx/Ag multilayered structure. The insertion of only single layer of poly(diallyl-dimethyl-ammonium chloride) (PDDA) cationic polymer film (or poly(ethyleneimine) (PEI) polymeric interfacial dipole layer) and titanium oxide nanosheet (TN) films as an ESL effectively improved cell performance. Abnormal S-shaped curves were observed in the inverted BHJ cells owing to the contact resistance across the ITO/active layer interface and the ITO/PDDA/TN/active layer interface. The series resistance across the ITO/ESL interface in the inverted BHJ cell was successfully reduced using an interfacial layer with a positively charged surface potential with respect to ITO base electrode. The positive dipole in PEI and the electronic charge phenomena at the electrophoretic deposited TN (ED-TN) films on ITO contributed to the reduction of the contact resistance at the electrode interface. The surface potential measurement revealed that the energy alignment by the transfer of electronic charges from the ED-TN to the base electrodes. The insertion of the ESL with a large positive surface potential reduced the potential barrier for the electron injection at ITO/TN interface and it improved the photovoltaic properties of the inverted cell with an ITO/TN/active layer/MoOx/Ag structure.

Fragile DNA Motifs Trigger Mutagenesis at Distant Chromosomal Loci in Saccharomyces cerevisiae

PubMed Central

Saini, Natalie; Zhang, Yu; Nishida, Yuri; Sheng, Ziwei; Choudhury, Shilpa; Mieczkowski, Piotr; Lobachev, Kirill S.

2013-01-01

DNA sequences capable of adopting non-canonical secondary structures have been associated with gross-chromosomal rearrangements in humans and model organisms. Previously, we have shown that long inverted repeats that form hairpin and cruciform structures and triplex-forming GAA/TTC repeats induce the formation of double-strand breaks which trigger genome instability in yeast. In this study, we demonstrate that breakage at both inverted repeats and GAA/TTC repeats is augmented by defects in DNA replication. Increased fragility is associated with increased mutation levels in the reporter genes located as far as 8 kb from both sides of the repeats. The increase in mutations was dependent on the presence of inverted or GAA/TTC repeats and activity of the translesion polymerase Polζ. Mutagenesis induced by inverted repeats also required Sae2 which opens hairpin-capped breaks and initiates end resection. The amount of breakage at the repeats is an important determinant of mutations as a perfect palindromic sequence with inherently increased fragility was also found to elevate mutation rates even in replication-proficient strains. We hypothesize that the underlying mechanism for mutagenesis induced by fragile motifs involves the formation of long single-stranded regions in the broken chromosome, invasion of the undamaged sister chromatid for repair, and faulty DNA synthesis employing Polζ. These data demonstrate that repeat-mediated breaks pose a dual threat to eukaryotic genome integrity by inducing chromosomal aberrations as well as mutations in flanking genes. PMID:23785298

E622, a miniature, virulence-associated mobile element.

PubMed

Stavrinides, John; Kirzinger, Morgan W B; Beasley, Federico C; Guttman, David S

2012-01-01

Miniature inverted terminal repeat elements (MITEs) are nonautonomous mobile elements that have a significant impact on bacterial evolution. Here we characterize E622, a 611-bp virulence-associated MITE from Pseudomonas syringae, which contains no coding region but has almost perfect 168-bp inverted repeats. Using an antibiotic coupling assay, we show that E622 is transposable and can mobilize an antibiotic resistance gene contained between its borders. Its predicted parent element, designated TnE622, has a typical transposon structure with a three-gene operon, consisting of resolvase, integrase, and exeA-like genes, which is bounded by the same terminal inverted repeats as E622. A broader genome level survey of the E622/TnE622 inverted repeats identified homologs in Pseudomonas, Salmonella, Shewanella, Erwinia, Pantoea, and the cyanobacteria Nostoc and Cyanothece, many of which appear to encompass known virulence genes, including genes encoding toxins, enzymes, and type III secreted effectors. Its association with niche-specific genetic determinants, along with its persistence and evolutionary diversification, indicates that this mobile element family has played a prominent role in the evolution of many agriculturally and clinically relevant pathogenic bacteria.

MoO3 Thickness, Thermal Annealing and Solvent Annealing Effects on Inverted and Direct Polymer Photovoltaic Solar Cells

PubMed Central

Chambon, Sylvain; Derue, Lionel; Lahaye, Michel; Pavageau, Bertrand; Hirsch, Lionel; Wantz, Guillaume

2012-01-01

Several parameters of the fabrication process of inverted polymer bulk heterojunction solar cells based on titanium oxide as an electron selective layer and molybdenum oxide as a hole selective layer were tested in order to achieve efficient organic photovoltaic solar cells. Thermal annealing treatment is a common process to achieve optimum morphology, but it proved to be damageable for the performance of this kind of inverted solar cells. We demonstrate using Auger analysis combined with argon etching that diffusion of species occurs from the MoO3/Ag top layers into the active layer upon thermal annealing. In order to achieve efficient devices, the morphology of the bulk heterojunction was then manipulated using the solvent annealing technique as an alternative to thermal annealing. The influence of the MoO3 thickness was studied on inverted, as well as direct, structure. It appeared that only 1 nm-thick MoO3 is enough to exhibit highly efficient devices (PCE = 3.8%) and that increasing the thickness up to 15 nm does not change the device performance.

Orbifold E-functions of dual invertible polynomials

NASA Astrophysics Data System (ADS)

Ebeling, Wolfgang; Gusein-Zade, Sabir M.; Takahashi, Atsushi

2016-08-01

An invertible polynomial is a weighted homogeneous polynomial with the number of monomials coinciding with the number of variables and such that the weights of the variables and the quasi-degree are well defined. In the framework of the search for mirror symmetric orbifold Landau-Ginzburg models, P. Berglund and M. Henningson considered a pair (f , G) consisting of an invertible polynomial f and an abelian group G of its symmetries together with a dual pair (f ˜ , G ˜) . We consider the so-called orbifold E-function of such a pair (f , G) which is a generating function for the exponents of the monodromy action on an orbifold version of the mixed Hodge structure on the Milnor fibre of f. We prove that the orbifold E-functions of Berglund-Henningson dual pairs coincide up to a sign depending on the number of variables and a simple change of variables. The proof is based on a relation between monomials (say, elements of a monomial basis of the Milnor algebra of an invertible polynomial) and elements of the whole symmetry group of the dual polynomial.

Interface inequivalence of the InP/InAlAs/InP staggered double heterostructure grown by metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Böhrer, J.; Krost, A.; Heitz, R.; Heinrichsdorff, F.; Eckey, L.; Bimberg, D.; Cerva, H.

1996-02-01

The optical and structural properties of the normal InAlAs on InP and the inverted InP on the InAlAs staggered band lineup interface grown by metalorganic chemical vapor deposition (MOCVD) are compared by use of transmission electron microscopy (TEM), time integrated, and time resolved photoluminescence. TEM images show that both interfaces are dissimilar. The normal interface is very abrupt. The inverted interface shows an additional graded layer of about 2.5 nm in width of In1-xAlxAsyP1-y with x (0.48-0) and y (1.0-0.0). A large optical anisotropy exists because of the inequivalence of the two interfaces. The larger spatial separation of the carriers at the inverted interface is responsible for a smaller overlap of the electron and hole wave functions and for that reason a one order of magnitude longer e-h luminescence decay time of 45 ns is observed. The normal interface transition shifts approximately to the third root of excitation while the inverted interface transition shifts logarithmically.

A novel control algorithm for interaction between surface waves and a permeable floating structure

NASA Astrophysics Data System (ADS)

Tsai, Pei-Wei; Alsaedi, A.; Hayat, T.; Chen, Cheng-Wu

2016-04-01

An analytical solution is undertaken to describe the wave-induced flow field and the surge motion of a permeable platform structure with fuzzy controllers in an oceanic environment. In the design procedure of the controller, a parallel distributed compensation (PDC) scheme is utilized to construct a global fuzzy logic controller by blending all local state feedback controllers. A stability analysis is carried out for a real structure system by using Lyapunov method. The corresponding boundary value problems are then incorporated into scattering and radiation problems. They are analytically solved, based on separation of variables, to obtain series solutions in terms of the harmonic incident wave motion and surge motion. The dependence of the wave-induced flow field and its resonant frequency on wave characteristics and structure properties including platform width, thickness and mass has been thus drawn with a parametric approach. From which mathematical models are applied for the wave-induced displacement of the surge motion. A nonlinearly inverted pendulum system is employed to demonstrate that the controller tuned by swarm intelligence method can not only stabilize the nonlinear system, but has the robustness against external disturbance.

Plateau growth around the Changma Basin in NE Tibet

NASA Astrophysics Data System (ADS)

Vernon, Rowan; Cunningham, Dickson; Zhang, Jin; England, Richard

2014-05-01

The Qilian Mountains form one of the most actively uplifting regions of the northeastern Tibetan Plateau and provide an opportunity to study the ongoing, intermediate stages of plateau growth. The crust of the Qilian Mountains consists of an orogenic collage of mid-Proterozoic to mid-Palaeozoic island arc terranes accreted to the North China Craton during the Palaeozoic. NE-directed compression related to the Indo-Asian collision began in the Early Neogene, uplifting fold-thrust mountain ranges which splay south-eastwards from the sinistral northeast-trending Altyn Tagh Fault (ATF). In this study, we investigate the post-Oligocene tectonic evolution of the northern margin of the Tibetan Plateau around the Changma Basin, at the very northeast corner of the Plateau, where the ATF forms a triple junction with the frontal Qilian Shan thrust. Our research involves synthesis of previous geological and geophysical data, remote sensing analysis and field mapping of structures along key transects. The Changma Basin is a relatively low intra-montane basin in the northeast Tibetan Plateau that is receiving alluvial infill from surrounding ranges, but is also being drained by the Su Le River, one of the largest river systems in the northeast Tibetan Plateau. The basin is also internally deforming and inverting along fault and fold zones, as well as being overthrust along some of its margins. Where older basement trends are parallel to neotectonic faults, some reactivation is inferred and locally documented through field observations. Otherwise, the post-Oligocene thrust and oblique-slip faults which are responsible for uplifting various basement blocks and inverting the Changma Basin appear discordant to nearby basement trends. Range-bounding thrust faults with the greatest along-strike continuity and relief generation are assumed to have the largest displacements, whereas other intra-range thrusts that bound uplifted limestone blocks are assumed to have lower amounts of displacement. Structural transects reveal a lack of intra-range reactivation of inherited structures or fabrics, concentrating uplift on the lithologically-controlled intra-range thrust faults and the major range-bounding thrust and oblique-slip faults. Northeast of the Changma Basin, in the Qilian Shan foreland, an east-trending belt of low folds and faulted ridges along the ATF marks the structural continuation of the Yumen Shan range. We find that uplift and growth of northeastern Tibet is complex with local variations in structural vergence, degree of strain partitioning, fault reactivation and basin inversion. This complexity reflects both the buttressing effect of the rigid Archaean basement directly to the north and the variation in the structural trends and lithologies of the Qilian basement, as well as the competition between uplift and erosion in the region.

Distributed cooperative control of AC microgrids

NASA Astrophysics Data System (ADS)

Bidram, Ali

In this dissertation, the comprehensive secondary control of electric power microgrids is of concern. Microgrid technical challenges are mainly realized through the hierarchical control structure, including primary, secondary, and tertiary control levels. Primary control level is locally implemented at each distributed generator (DG), while the secondary and tertiary control levels are conventionally implemented through a centralized control structure. The centralized structure requires a central controller which increases the reliability concerns by posing the single point of failure. In this dissertation, the distributed control structure using the distributed cooperative control of multi-agent systems is exploited to increase the secondary control reliability. The secondary control objectives are microgrid voltage and frequency, and distributed generators (DGs) active and reactive powers. Fully distributed control protocols are implemented through distributed communication networks. In the distributed control structure, each DG only requires its own information and the information of its neighbors on the communication network. The distributed structure obviates the requirements for a central controller and complex communication network which, in turn, improves the system reliability. Since the DG dynamics are nonlinear and non-identical, input-output feedback linearization is used to transform the nonlinear dynamics of DGs to linear dynamics. Proposed control frameworks cover the control of microgrids containing inverter-based DGs. Typical microgrid test systems are used to verify the effectiveness of the proposed control protocols.

An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources.

PubMed

Weichsel, T; Hartung, U; Kopte, T; Zschornack, G; Kreller, M; Silze, A

2014-05-01

An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10(10) cm(-3) to 1 × 10(11) cm(-3), when the magnetron plasma is exposed to the magnetic mirror field of the ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10(18) atoms/s for aluminum, which meets the demand for the production of a milliampere Al(+) ion beam.

Approximate non-linear multiparameter inversion for multicomponent single and double P-wave scattering in isotropic elastic media

NASA Astrophysics Data System (ADS)

Ouyang, Wei; Mao, Weijian

2018-03-01

An asymptotic quadratic true-amplitude inversion method for isotropic elastic P waves is proposed to invert medium parameters. The multicomponent P-wave scattered wavefield is computed based on a forward relationship using second-order Born approximation and corresponding high-frequency ray theoretical methods. Within the local double scattering mechanism, the P-wave transmission factors are elaborately calculated, which results in the radiation pattern for P-waves scattering being a quadratic combination of the density and Lamé's moduli perturbation parameters. We further express the elastic P-wave scattered wavefield in a form of generalized Radon transform (GRT). After introducing classical backprojection operators, we obtain an approximate solution of the inverse problem by solving a quadratic non-linear system. Numerical tests with synthetic data computed by finite-differences scheme demonstrate that our quadratic inversion can accurately invert perturbation parameters for strong perturbations, compared with the P-wave single-scattering linear inversion method. Although our inversion strategy here is only syncretized with P-wave scattering, it can be extended to invert multicomponent elastic data containing both P-wave and S-wave information.

Approximate nonlinear multiparameter inversion for multicomponent single and double P-wave scattering in isotropic elastic media

NASA Astrophysics Data System (ADS)

Ouyang, Wei; Mao, Weijian

2018-07-01

An asymptotic quadratic true-amplitude inversion method for isotropic elastic P waves is proposed to invert medium parameters. The multicomponent P-wave scattered wavefield is computed based on a forward relationship using second-order Born approximation and corresponding high-frequency ray theoretical methods. Within the local double scattering mechanism, the P-wave transmission factors are elaborately calculated, which results in the radiation pattern for P-wave scattering being a quadratic combination of the density and Lamé's moduli perturbation parameters. We further express the elastic P-wave scattered wavefield in a form of generalized Radon transform. After introducing classical backprojection operators, we obtain an approximate solution of the inverse problem by solving a quadratic nonlinear system. Numerical tests with synthetic data computed by finite-differences scheme demonstrate that our quadratic inversion can accurately invert perturbation parameters for strong perturbations, compared with the P-wave single-scattering linear inversion method. Although our inversion strategy here is only syncretized with P-wave scattering, it can be extended to invert multicomponent elastic data containing both P- and S-wave information.

Fine-scale thermohaline ocean structure retrieved with 2-D prestack full-waveform inversion of multichannel seismic data: Application to the Gulf of Cadiz (SW Iberia)

NASA Astrophysics Data System (ADS)

Dagnino, D.; Sallarès, V.; Biescas, B.; Ranero, C. R.

2016-08-01

This work demonstrates the feasibility of 2-D time-domain, adjoint-state acoustic full-waveform inversion (FWI) to retrieve high-resolution models of ocean physical parameters such as sound speed, temperature and salinity. The proposed method is first described and then applied to prestack multichannel seismic (MCS) data acquired in the Gulf of Cadiz (SW Iberia) in 2007 in the framework of the Geophysical Oceanography project. The inversion strategy flow includes specifically designed data preconditioning for acoustic noise reduction, followed by the inversion of sound speed in the shotgather domain. We show that the final sound speed model has a horizontal resolution of ˜ 70 m, which is two orders of magnitude better than that of the initial model constructed with coincident eXpendable Bathy Thermograph (XBT) data, and close to the theoretical resolution of O(λ). Temperature (T) and salinity (S) are retrieved with the same lateral resolution as sound speed by combining the inverted sound speed model with the thermodynamic equation of seawater and a local, depth-dependent T-S relation derived from regional conductivity-temperature-depth (CTD) measurements of the National Oceanic and Atmospheric Administration (NOAA) database. The comparison of the inverted T and S models with XBT and CTD casts deployed simultaneously to the MCS acquisition shows that the thermohaline contrasts are resolved with an accuracy of 0.18oC for temperature and 0.08 PSU for salinity. The combination of oceanographic and MCS data into a common, pseudo-automatic inversion scheme allows to quantitatively resolve submeso-scale features that ought to be incorporated into larger-scale ocean models of oceans structure and circulation.

Annealing Effect on (FAPbI3)1−x(MAPbBr3)x Perovskite Films in Inverted-Type Perovskite Solar Cells

PubMed Central

Chen, Lung-Chien; Wu, Jia-Ren; Tseng, Zhong-Liang; Chen, Cheng-Chiang; Chang, Sheng Hsiung; Huang, Jun-Kai; Lee, King-Lien; Cheng, Hsin-Ming

2016-01-01

This study determines the effects of annealing treatment on the structure and the optical and electronic behaviors of the mixed (FAPbI3)1−x(MAPbBr3)x perovskite system. The experimental results reveal that (FAPbI3)1−x(MAPbBr3)x (x ~ 0.2) is an effective light-absorbing material for use in inverted planar perovskite solar cells owing to its large absorbance and tunable band gap. Therefore, good band-matching between the (FAPbI3)1−x(MAPbBr3)x and C60 in photovoltaic devices can be controlled by annealing at various temperatures. Accordingly, an inverted mixed perovskite solar cell with a record efficiency of 12.0% under AM1.5G irradiation is realized. PMID:28773874

Structure Matters: The Role of Clique Hierarchy in the Relationship Between Adolescent Social Status and Aggression and Prosociality.

PubMed

Pattiselanno, Kim; Dijkstra, Jan Kornelis; Steglich, Christian; Vollebergh, Wilma; Veenstra, René

2015-12-01

Peer cliques form an important context for the social development of adolescents. Although clique members are often similar in social status, also within cliques, status differences exist. How differences in social status between clique members are related to behaviors of its individual members is rather unknown. This study examined to what extent the relationship of individual social status (i.e., perceived popularity) with aggression and prosocial behavior depends on the level of internal clique hierarchy. The sample consists of 2674 adolescents (49.8% boys), with a mean age of 14.02. We focused specifically on physical and relational aggression, and practical and emotional support, because these behaviors have shown to be of great importance for social relationships and social standing among adolescents. The internal status hierarchy of cliques was based on the variation in individual social status between clique members (i.e., clique hierarchization) and the structure of status scores within a clique (pyramid shape, inverted pyramid, or equal distribution of social status scores) (i.e., clique status structure). The results showed that differences in aggressive and prosocial behaviors were particularly moderated by clique status structure: aggression was stronger related to individual social status in (girls') cliques where the clique status structure reflected an inverted pyramid with relatively more high status adolescents within the clique than low status peers, and prosocial behavior showed a significant relationship with individual social status, again predominantly in inverted pyramid structured (boys' and girls') cliques. Furthermore, these effects differed by types of gender cliques: the associations were found in same gender but not mixed-gender cliques. The findings stress the importance of taking into account internal clique characteristics when studying adolescent social status in relationship to aggression and prosociality.

Complex fold and thrust belt structural styles: Examples from the Greater Juha area of the Papuan Fold and Thrust Belt, Papua New Guinea

NASA Astrophysics Data System (ADS)

Mahoney, Luke; Hill, Kevin; McLaren, Sandra; Hanani, Amanda

2017-07-01

The remote and inhospitable Papuan Fold Belt in Papua New Guinea is one of the youngest yet least well-documented fold and thrust belts on Earth. Within the frontal Greater Juha area we have carried out >100 km of geological traverses and associated analyses that have added significantly to the contemporary geological and geophysical dataset. Our structural analysis provides evidence of major inversion, detachment and triangle zone faults within the uplifted Eastern Muller Ranges. We have used the dataset to develop a quasi-3D model for the Greater Juha area, with associated cross-sections revealing that the exposed Cenozoic Darai Limestone is well-constrained with very low shortening of 12.6-21.4% yet structures are elevated up to 7 km above regional. We suggest the inversion of pre-existing rift architecture is the primary influence on the evolution of the area and that structures link to the surface via triangle zones and detachment faults within the incompetent Mesozoic passive-margin sedimentary sequence underlying competent Darai Limestone. Arc-normal oriented structures, dominantly oblique dextral, up-to-the-southeast, are pervasive across a range of scales and are here interpreted to relate at depth to weakened pre-existing basement cross-structures. It is proposed that Palaeozoic basement fabric controlled the structural framework of the basin during Early Mesozoic rifting forming regional-scale accommodation zones and related local-scale transfer structures that are now expressed as regional-scale arc-normal lineaments and local-scale arc-normal structures, respectively. Transfer structures, including complexly breached relay ramps, utilise northeast-southwest striking weaknesses associated with the basement fabric, as a mechanism for accommodating displacement along major northwest-southeast striking normal faults. These structures have subsequently been inverted to form arc-normal oriented zones of tear faulting that accommodate laterally variable displacement along inversion faults and connected thrust structures.

Advanced Liquid Cooling for a Traction Drive Inverter Using Jet Impingement and Microfinned Enhanced Surfaces: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waye, S. K.; Narumanchi, S.; Mihalic, M.

2014-08-01

Jet impingement on plain and micro-finned enhanced surfaces was compared to a traditional channel flow configuration. The jets provide localized cooling to areas heated by the insulated-gate bipolar transistor and diode devices. Enhanced microfinned surfaces increase surface area and thermal performance. Using lighter materials and designing the fluid path to manage pressure losses increases overall performance while reducing weight, volume, and cost. Powering four diodes in the center power module of the inverter and computational fluid dynamics (CFD) modeling was used to characterize the baseline as well as jet-impingement-based heat exchangers. CFD modeling showed the thermal performance improvements should holdmore » for a fully powered inverter. Increased thermal performance was observed for the jet-impingement configurations when tested at full inverter power (40 to 100 kW output power) on a dynamometer. The reliability of the jets and enhanced surfaces over time was also investigated. Experimentally, the junction-to- coolant thermal resistance was reduced by up to 12.5% for jet impingement on enhanced surfaces s compared to the baseline channel flow configuration. Base plate-to-coolant (convective) resistance was reduced by up to 37.0% for the jet-based configuration compared to the baseline, suggesting that while improvements to the cooling side reduce overall resistance, reducing the passive stack resistance may contribute to lowering overall junction-to-coolant resistance. Full inverter power testing showed reduced thermal resistance from the middle of the module baseplate to coolant of up to 16.5%. Between the improvement in thermal performance and pumping power, the coefficient of performance improved by up to 13% for the jet-based configuration.« less

Approaches to linear local gauge-invariant observables in inflationary cosmologies

NASA Astrophysics Data System (ADS)

Fröb, Markus B.; Hack, Thomas-Paul; Khavkine, Igor

2018-06-01

We review and relate two recent complementary constructions of linear local gauge-invariant observables for cosmological perturbations in generic spatially flat single-field inflationary cosmologies. After briefly discussing their physical significance, we give explicit, covariant and mutually invertible transformations between the two sets of observables, thus resolving any doubts about their equivalence. In this way, we get a geometric interpretation and show the completeness of both sets of observables, while previously each of these properties was available only for one of them.

Generalized Preconditioned Locally Harmonic Residual Eigensolver (GPLHR) v0.1

DOE Office of Scientific and Technical Information (OSTI.GOV)

VECHARYNSKI, EUGENE; YANG, CHAO

The software contains a MATLAB implementation of the Generalized Preconditioned Locally Harmonic Residual (GPLHR) method for solving standard and generalized non-Hermitian eigenproblems. The method is particularly useful for computing a subset of eigenvalues, and their eigen- or Schur vectors, closest to a given shift. The proposed method is based on block iterations and can take advantage of a preconditioner if it is available. It does not need to perform exact shift-and-invert transformation. Standard and generalized eigenproblems are handled in a unified framework.

Photovoltaic Performance of Inverted Polymer Solar Cells Using Hybrid Carbon Quantum Dots and Absorption Polymer Materials

NASA Astrophysics Data System (ADS)

Lim, Hwain; Lee, Kyu Seung; Liu, Yang; Kim, Hak Yong; Son, Dong Ick

2018-05-01

We report the synthesis and characterization of the carbon quantum dots (C-dots) easily obtained from citric acid and ethanediamine, and also investigated structural, optical and electrical properties. The C-dots have extraordinary optical and electrical features such as absorption of ultraviolet range and effective interface for charge separation and transport in active layer, which make them attractive materials for applications in photovoltaic devices (PV). The C-dots play important roles in charge extraction in the PV structures, they can be synthesized by a simple method and used to insert in active layer of polymer solar cells. In this study, we demonstrate that improve charge transport properties of inverted polymer solar cells (iPSCs) with C-dots and structural, optical and electrical properties of C-dots. As a result, iPSCs with C-dots showed enhancement of more than 30% compared with that of the contrast device in power conversion efficiency.

High Resolution Shear-Wave Velocity Structure of Greenland from Surface Wave Analysis

NASA Astrophysics Data System (ADS)

Pourpoint, M.; Anandakrishnan, S.; Ammon, C. J.

2016-12-01

We present a high resolution seismic tomography model of Greenland's lithosphere from the analysis of fundamental mode Rayleigh-wave group velocity dispersion measurements. Regional and teleseismic events recorded by the GLISN, GSN and CN seismic networks over the last 20 years were used. In order to better constrain the crustal structure of Greenland, we also collected and processed several years of ambient noise data. We developed a new group velocity correction method that helps to alleviate the limitations of the sparse Greenland station network and the relatively few local events. The global dispersion model GDM52 from Ekström [2011] was used to calculate group delays from the earthquake to the boundaries of our study area. An iterative reweighted generalized least-square approach was used to invert for the group velocity maps between periods of 5 s and 180 s. A Markov chain Monte Carlo technique was then applied to invert for a 3-D shear wave velocity model of Greenland up to a depth of 200 km and estimate the uncertainties in the model. Our method results in relatively uniform azimuthal coverage and high resolution length ( 200 to 400 km) in west and east Greenland. We detect a deep high velocity zone extending from northwestern to southwestern Greenland and a low velocity zone (LVZ) between central-eastern and northeastern Greenland. The location of the LVZ correlates well with a previously measured high geothermal heat flux and could provide valuable information about its source. We expect the results of the ambient noise tomography to cross-validate the earthquake tomography results and give us a better estimate of the spatial extent and amplitude of the LVZ at shallow depths. A refined regional model of Greenland's lithospheric structure should eventually help better understand how underlying geological and geophysical processes may impact the dynamics of the ice sheet and influence its potential contribution to future sea level changes.

Accretionary nature of the crust of Central and East Java (Indonesia) revealed by local earthquake travel-time tomography

NASA Astrophysics Data System (ADS)

Haberland, Christian; Bohm, Mirjam; Asch, Günter

2014-12-01

Reassessment of travel time data from an exceptionally dense, amphibious, temporary seismic network on- and offshore Central and Eastern Java (MERAMEX) confirms the accretionary nature of the crust in this segment of the Sunda subduction zone (109.5-111.5E). Traveltime data of P- and S-waves of 244 local earthquakes were tomographically inverted, following a staggered inversion approach. The resolution of the inversion was inspected by utilizing synthetic recovery tests and analyzing the model resolution matrix. The resulting images show a highly asymmetrical crustal structure. The images can be interpreted to show a continental fragment of presumably Gondwana origin in the coastal area (east of 110E), which has been accreted to the Sundaland margin. An interlaced anomaly of high seismic velocities indicating mafic material can be interpreted to be the mantle part of the continental fragment, or part of obducted oceanic lithosphere. Lower than average crustal velocities of the Java crust are likely to reflect ophiolitic and metamorphic rocks of a subduction melange.

Multidisciplinary Approach to the Science and Technology of Sub-Micron Electronics.

DTIC Science & Technology

1987-03-10

19densities as high as 3x1O1 2 electrons cm- 2 could be obtained with GaAs doping densities on the order of 3x1O18 cm-3 . Many-body effects are shown to be...heterinterfaces include studies of the effects of paramagnetic impurities and structural disorder at the interface of mismatched Mo-Ni superlattices in Dr...inverted mecelles. The ’caoing’ effect of the inverted micelles ensures a narrow distribution of particle size, and a uniform composition. This

NREL Studies Voltage Regulation Strategies for Hawaiian Electric Companies

Science.gov Websites

, electric vehicles, and electric water heater control to understand their potential in supporting voltage locally. Meanwhile, NREL has also completed a pilot inverter control study, in which data from advanced voltage regulation, such as battery storage, water heater control, and electric vehicles, will be done

Megabase-Scale Inversion Polymorphism in the Wild Ancestor of Maize

PubMed Central

Fang, Zhou; Pyhäjärvi, Tanja; Weber, Allison L.; Dawe, R. Kelly; Glaubitz, Jeffrey C.; González, José de Jesus Sánchez; Ross-Ibarra, Claudia; Doebley, John; Morrell, Peter L.; Ross-Ibarra, Jeffrey

2012-01-01

Chromosomal inversions are thought to play a special role in local adaptation, through dramatic suppression of recombination, which favors the maintenance of locally adapted alleles. However, relatively few inversions have been characterized in population genomic data. On the basis of single-nucleotide polymorphism (SNP) genotyping across a large panel of Zea mays, we have identified an ∼50-Mb region on the short arm of chromosome 1 where patterns of polymorphism are highly consistent with a polymorphic paracentric inversion that captures >700 genes. Comparison to other taxa in Zea and Tripsacum suggests that the derived, inverted state is present only in the wild Z. mays subspecies parviglumis and mexicana and is completely absent in domesticated maize. Patterns of polymorphism suggest that the inversion is ancient and geographically widespread in parviglumis. Cytological screens find little evidence for inversion loops, suggesting that inversion heterozygotes may suffer few crossover-induced fitness consequences. The inversion polymorphism shows evidence of adaptive evolution, including a strong altitudinal cline, a statistical association with environmental variables and phenotypic traits, and a skewed haplotype frequency spectrum for inverted alleles. PMID:22542971

Ionospheric current source modeling and global geomagnetic induction using ground geomagnetic observatory data

USGS Publications Warehouse

Sun, Jin; Kelbert, Anna; Egbert, G.D.

2015-01-01

Long-period global-scale electromagnetic induction studies of deep Earth conductivity are based almost exclusively on magnetovariational methods and require accurate models of external source spatial structure. We describe approaches to inverting for both the external sources and three-dimensional (3-D) conductivity variations and apply these methods to long-period (T≥1.2 days) geomagnetic observatory data. Our scheme involves three steps: (1) Observatory data from 60 years (only partly overlapping and with many large gaps) are reduced and merged into dominant spatial modes using a scheme based on frequency domain principal components. (2) Resulting modes are inverted for corresponding external source spatial structure, using a simplified conductivity model with radial variations overlain by a two-dimensional thin sheet. The source inversion is regularized using a physically based source covariance, generated through superposition of correlated tilted zonal (quasi-dipole) current loops, representing ionospheric source complexity smoothed by Earth rotation. Free parameters in the source covariance model are tuned by a leave-one-out cross-validation scheme. (3) The estimated data modes are inverted for 3-D Earth conductivity, assuming the source excitation estimated in step 2. Together, these developments constitute key components in a practical scheme for simultaneous inversion of the catalogue of historical and modern observatory data for external source spatial structure and 3-D Earth conductivity.

Compact plane illumination plugin device to enable light sheet fluorescence imaging of multi-cellular organisms on an inverted wide-field microscope

PubMed Central

Guan, Zeyi; Lee, Juhyun; Jiang, Hao; Dong, Siyan; Jen, Nelson; Hsiai, Tzung; Ho, Chih-Ming; Fei, Peng

2015-01-01

We developed a compact plane illumination plugin (PIP) device which enabled plane illumination and light sheet fluorescence imaging on a conventional inverted microscope. The PIP device allowed the integration of microscope with tunable laser sheet profile, fast image acquisition, and 3-D scanning. The device is both compact, measuring approximately 15 by 5 by 5 cm, and cost-effective, since we employed consumer electronics and an inexpensive device molding method. We demonstrated that PIP provided significant contrast and resolution enhancement to conventional microscopy through imaging different multi-cellular fluorescent structures, including 3-D branched cells in vitro and live zebrafish embryos. Imaging with the integration of PIP greatly reduced out-of-focus contamination and generated sharper contrast in acquired 2-D plane images when compared with the stand-alone inverted microscope. As a result, the dynamic fluid domain of the beating zebrafish heart was clearly segmented and the functional monitoring of the heart was achieved. Furthermore, the enhanced axial resolution established by thin plane illumination of PIP enabled the 3-D reconstruction of the branched cellular structures, which leads to the improvement on the functionality of the wide field microscopy. PMID:26819828

Compact plane illumination plugin device to enable light sheet fluorescence imaging of multi-cellular organisms on an inverted wide-field microscope.

PubMed

Guan, Zeyi; Lee, Juhyun; Jiang, Hao; Dong, Siyan; Jen, Nelson; Hsiai, Tzung; Ho, Chih-Ming; Fei, Peng

2016-01-01

We developed a compact plane illumination plugin (PIP) device which enabled plane illumination and light sheet fluorescence imaging on a conventional inverted microscope. The PIP device allowed the integration of microscope with tunable laser sheet profile, fast image acquisition, and 3-D scanning. The device is both compact, measuring approximately 15 by 5 by 5 cm, and cost-effective, since we employed consumer electronics and an inexpensive device molding method. We demonstrated that PIP provided significant contrast and resolution enhancement to conventional microscopy through imaging different multi-cellular fluorescent structures, including 3-D branched cells in vitro and live zebrafish embryos. Imaging with the integration of PIP greatly reduced out-of-focus contamination and generated sharper contrast in acquired 2-D plane images when compared with the stand-alone inverted microscope. As a result, the dynamic fluid domain of the beating zebrafish heart was clearly segmented and the functional monitoring of the heart was achieved. Furthermore, the enhanced axial resolution established by thin plane illumination of PIP enabled the 3-D reconstruction of the branched cellular structures, which leads to the improvement on the functionality of the wide field microscopy.

Localization in covariance matrices of coupled heterogenous Ornstein-Uhlenbeck processes

NASA Astrophysics Data System (ADS)

Barucca, Paolo

2014-12-01

We define a random-matrix ensemble given by the infinite-time covariance matrices of Ornstein-Uhlenbeck processes at different temperatures coupled by a Gaussian symmetric matrix. The spectral properties of this ensemble are shown to be in qualitative agreement with some stylized facts of financial markets. Through the presented model formulas are given for the analysis of heterogeneous time series. Furthermore evidence for a localization transition in eigenvectors related to small and large eigenvalues in cross-correlations analysis of this model is found, and a simple explanation of localization phenomena in financial time series is provided. Finally we identify both in our model and in real financial data an inverted-bell effect in correlation between localized components and their local temperature: high- and low-temperature components are the most localized ones.

Relationship between field-aligned currents and inverted-V parallel potential drops observed at midaltitudes

NASA Astrophysics Data System (ADS)

Sakanoi, T.; Fukunishi, H.; Mukai, T.

1995-10-01

The inverted-V field-aligned acceleration region existing in the altitude range of several thousand kilometers plays an essential role for the magnetosphere-ionosphere coupling system. The adiabatic plasma theory predicts a linear relationship between field-aligned current density (J∥) and parallel potential drop (Φ∥), that is, J∥=KΦ∥, where K is the field-aligned conductance. We examined this relationship using the charged particle and magnetic field data obtained from the Akebono (Exos D) satellite. The potential drop above the satellite was derived from the peak energy of downward electrons, while the potential drop below the satellite was derived from two different methods: the peak energy of upward ions and the energy-dependent widening of electron loss cone. On the other hand, field-aligned current densities in the inverted-V region were estimated from the Akebono magnetometer data. Using these potential drops and field-aligned current densities, we estimated the linear field-aligned conductance KJΦ. Further, we obtained the corrected field-aligned conductance KCJΦ by applying the full Knight's formula to the current-voltage relationship. We also independently estimated the field-aligned conductance KTN from the number density and the thermal temperature of magnetospheric source electrons which were obtained by fitting accelerated Maxwellian functions for precipitating electrons. The results are summarized as follows: (1) The latitudinal dependence of parallel potential drops is characterized by a narrow V-shaped structure with a width of 0.4°-1.0°. (2) Although the inverted-V potential region exactly corresponds to the upward field aligned current region, the latitudinal dependence of upward current intensity is an inverted-U shape rather than an inverted-V shape. Thus it is suggested that the field-aligned conductance KCJΦ changes with a V-shaped latitudinal dependence. In many cases, KCJΦ values at the edge of the inverted-V region are about 5-10 times larger than those at the center. (3) By comparing KCJΦ with KTN, KCJΦ is found to be about 2-20 times larger than KTN. These results suggest that low-energy electrons such as trapped electrons, secondary and back-scattered electrons, and ionospheric electrons significantly contribute to upward field-aligned currents in the inverted-V region. It is therefore inferred that non adiabatic pitch angle scattering processes play an important role in the inverted-V region. .

Tomographic models and seismotectonics of the Reggio Emilia region, Italy

NASA Astrophysics Data System (ADS)

Ciaccio, M. G.; Chiarabba, C.

2002-02-01

The aim of this study is to define the Vp and Vp/Vs structure of the fault zone ruptured by the M L 5.1 earthquake of October 15, 1996 which occurred near Reggio Emilia (central-northern Italy). A 1-month-long seismic sequence followed the mainshock and occurred in a small region along the outer border of the northern Apenninic belt, at depth ranging between 10 and 17 km. P- and S-wave arrival times from 304 aftershocks recorded by two local dense seismic arrays installed in the epicentral region have been inverted to obtain one- and three-dimensional velocity models by using state of the art local earthquake tomographic techniques. Velocity models and aftershock relocation help us to infer the seismotectonic of the region. Earthquakes originated along a NW-dipping backthrust of a NE-trending main thrust, composing the western part of the broad Ferrara Arc. A main high Vp and high Vp/Vs region delineates a pop-up structure in the center of the area. The high Vp/Vs within the pop-up structure supports the presence of a zone with increased pore pressure. The hypocentral depth of both mainshock and aftershocks is greater than those usually found for the main seismogenic regions of the Apenninic belt. P-wave velocity values in the seismogenic area, obtained by tomography, are compatible with rocks of the Mesozoic cover and suggest that seismicity occurred within the Mesozoic units stack at present by compressional tectonics.

Improving generalized inverted index lock wait times

NASA Astrophysics Data System (ADS)

Borodin, A.; Mirvoda, S.; Porshnev, S.; Ponomareva, O.

2018-01-01

Concurrent operations on tree like data structures is a cornerstone of any database system. Concurrent operations intended for improving read\\write performance and usually implemented via some way of locking. Deadlock-free methods of concurrency control are known as tree locking protocols. These protocols provide basic operations(verbs) and algorithm (ways of operation invocations) for applying it to any tree-like data structure. These algorithms operate on data, managed by storage engine which are very different among RDBMS implementations. In this paper, we discuss tree locking protocol implementation for General inverted index (Gin) applied to multiversion concurrency control (MVCC) storage engine inside PostgreSQL RDBMS. After that we introduce improvements to locking protocol and provide usage statistics about evaluation of our improvement in very high load environment in one of the world’s largest IT company.

Energy and pitch angle-dispersed auroral electrons suggesting a time-variable, inverted-V potential structure

NASA Astrophysics Data System (ADS)

Arnoldy, R. L.; Lynch, K. A.; Austin, J. B.; Kintner, P. M.

1999-10-01

High temporal resolution electron detectors aboard the PHAZE II rocket flight have shown that the energy-dispersed, field-aligned bursts (FABs) are time coincident with pitch angle-dispersed electrons having energies at the maximum voltage of the inverted-V potential. This modulation of the energetic inverted-V electrons is superimposed upon an energy-diffused background resulting in a peak-to-valley ratio of ~2 for the pitch angle-dispersed electrons. Since the characteristic energy of the FABs, the order of an eV, is considerably less than that of the plasma sheet electrons (the order of a keV) presumably falling through the inverted-V potential to create the discrete aurora, the modulation mechanism has to be independent of the electron temperature. The mechanism must accelerate the cold electrons over a range of energies from the inverted-V energy down to a few tens of eV. It must do this at the same time it is creating a population of hot, pitch angle-dispersed electrons at the inverted-V energy. Both the energy dispersion of the FABs and the pitch angle dispersion of the inverted-V electrons can be used to determine a source height assuming both populations start from the same source region at the same time. These calculations give source heights between 3500 and 5300 km for various events and disagreement between the two methods the order of 20%, which is within the rather substantial error limits of both calculations. A simple mechanism of providing a common start time for both populations of electrons would be a turning on/off of a spatially limited (vertically), inverted-V potential. The energy-dispersed FABs can be reconstructed at rocket altitudes if one assumes that cold electrons are accelerated to an energy determined by how much of the inverted-V potential they fall through when it is turned on. Similarly, the pitch angle-dispersed, inverted-V electrons can be modeled at rocket altitudes if one assumes that the plasma sheet electrons falling through the entire potential drop all start to do so at the same time when the potential is turned on. The FABs seem to fluctuate at either ~10 Hz or near 100 Hz. An important constraint of the on/off mechanism is whether cold electrons (1 eV) can fill the inverted-V volume during the off cycle. The maximum vertical height of the 10 kV potential region for the 10 Hz events would be the order of 100 and 10 km for the 100 Hz events. To get 10 kV, these heights require parallel electric fields of 0.1 and 1 V/m respectively for the 10 and 100 Hz events assuming that the filling is along B from below the inverted-V potential. Alternative mechanisms are also discussed in the light of the data presented.

Graph state generation with noisy mirror-inverting spin chains

NASA Astrophysics Data System (ADS)

Clark, Stephen R.; Klein, Alexander; Bruderer, Martin; Jaksch, Dieter

2007-06-01

We investigate the influence of noise on a graph state generation scheme which exploits a mirror inverting spin chain. Within this scheme the spin chain is used repeatedly as an entanglement bus (EB) to create multi-partite entanglement. The noise model we consider comprises of each spin of this EB being exposed to independent local noise which degrades the capabilities of the EB. Here we concentrate on quantifying its performance as a single-qubit channel and as a mediator of a two-qubit entangling gate, since these are basic operations necessary for graph state generation using the EB. In particular, for the single-qubit case we numerically calculate the average channel fidelity and whether the channel becomes entanglement breaking, i.e. expunges any entanglement the transferred qubit may have with other external qubits. We find that neither local decay nor dephasing noise cause entanglement breaking. This is in contrast to local thermal and depolarizing noise where we determine a critical length and critical noise coupling, respectively, at which entanglement breaking occurs. The critical noise coupling for local depolarizing noise is found to exhibit a power-law dependence on the chain length. For two-qubits we similarly compute the average gate fidelity and whether the ability for this gate to create entanglement is maintained. The concatenation of these noisy gates for the construction of a five-qubit linear cluster state and a Greenberger Horne Zeilinger state indicates that the level of noise that can be tolerated for graph state generation is tightly constrained.

Analysis, control and design of a non-inverting buck-boost converter: A bump-less two-level T-S fuzzy PI control.

PubMed

Almasi, Omid Naghash; Fereshtehpoor, Vahid; Khooban, Mohammad Hassan; Blaabjerg, Frede

2017-03-01

In this paper, a new modified fuzzy Two-Level Control Scheme (TLCS) is proposed to control a non-inverting buck-boost converter. Each level of fuzzy TLCS consists of a tuned fuzzy PI controller. In addition, a Takagi-Sugeno-Kang (TSK) fuzzy switch proposed to transfer the fuzzy PI controllers to each other in the control system. The major difficulty in designing fuzzy TLCS which degrades its performance is emerging unwanted drastic oscillations in the converter output voltage during replacing the controllers. Thereby, the fuzzy PI controllers in each level of TLCS structure are modified to eliminate these oscillations and improve the system performance. Some simulations and digital signal processor based experiments are conducted on a non-inverting buck-boost converter to support the effectiveness of the proposed TLCS in controlling the converter output voltage. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

MgZnO High Voltage Thin Film Transistors on Glass for Inverters in Building Integrated Photovoltaics

DOE PAGES

Hong, Wen-Chiang; Ku, Chieh-Jen; Li, Rui; ...

2016-10-10

Building integrated photovoltaics (BIPV) have attracted considerable interests because of its aesthetically attractive appearance and overall low cost. In BIPV, system integration on a glass substrate like windows is essential to cover a large area of a building with low cost. But, the conventional high voltage devices in inverters have to be built on the specially selected single crystal substrates, limiting its application for large area electronic systems, such as the BIPV. We demonstrate a Magnesium Zinc Oxide (MZO) based high voltage thin film transistor (HVTFT) built on a transparent glass substrate. We designed devices with unique ring-type structures andmore » use modulated Mg doping in the channel - gate dielectric interface, resulting in a blocking voltage of over 600 V. In addition to BIPV, the MZO HVTFT based inverter technology also creates new opportunities for emerging self-powered smart glass.« less

Transition from direct to inverted charge transport Marcus regions in molecular junctions via molecular orbital gating

NASA Astrophysics Data System (ADS)

Yuan, Li; Wang, Lejia; Garrigues, Alvar R.; Jiang, Li; Annadata, Harshini Venkata; Anguera Antonana, Marta; Barco, Enrique; Nijhuis, Christian A.

2018-04-01

Solid-state molecular tunnel junctions are often assumed to operate in the Landauer regime, which describes essentially activationless coherent tunnelling processes. In solution, on the other hand, charge transfer is described by Marcus theory, which accounts for thermally activated processes. In practice, however, thermally activated transport phenomena are frequently observed also in solid-state molecular junctions but remain poorly understood. Here, we show experimentally the transition from the Marcus to the inverted Marcus region in a solid-state molecular tunnel junction by means of intra-molecular orbital gating that can be tuned via the chemical structure of the molecule and applied bias. In the inverted Marcus region, charge transport is incoherent, yet virtually independent of temperature. Our experimental results fit well to a theoretical model that combines Landauer and Marcus theories and may have implications for the interpretation of temperature-dependent charge transport measurements in molecular junctions.

MgZnO High Voltage Thin Film Transistors on Glass for Inverters in Building Integrated Photovoltaics.

PubMed

Hong, Wen-Chiang; Ku, Chieh-Jen; Li, Rui; Abbaslou, Siamak; Reyes, Pavel; Wang, Szu-Ying; Li, Guangyuan; Lu, Ming; Sheng, Kuang; Lu, Yicheng

2016-10-10

Building integrated photovoltaics (BIPV) have attracted considerable interests because of its aesthetically attractive appearance and overall low cost. In BIPV, system integration on a glass substrate like windows is essential to cover a large area of a building with low cost. However, the conventional high voltage devices in inverters have to be built on the specially selected single crystal substrates, limiting its application for large area electronic systems, such as the BIPV. We demonstrate a Magnesium Zinc Oxide (MZO) based high voltage thin film transistor (HVTFT) built on a transparent glass substrate. The devices are designed with unique ring-type structures and use modulated Mg doping in the channel - gate dielectric interface, resulting in a blocking voltage of over 600 V. In addition to BIPV, the MZO HVTFT based inverter technology also creates new opportunities for emerging self-powered smart glass.

MgZnO High Voltage Thin Film Transistors on Glass for Inverters in Building Integrated Photovoltaics

PubMed Central

Hong, Wen-Chiang; Ku, Chieh-Jen; Li, Rui; Abbaslou, Siamak; Reyes, Pavel; Wang, Szu-Ying; Li, Guangyuan; Lu, Ming; Sheng, Kuang; Lu, Yicheng

2016-01-01

Building integrated photovoltaics (BIPV) have attracted considerable interests because of its aesthetically attractive appearance and overall low cost. In BIPV, system integration on a glass substrate like windows is essential to cover a large area of a building with low cost. However, the conventional high voltage devices in inverters have to be built on the specially selected single crystal substrates, limiting its application for large area electronic systems, such as the BIPV. We demonstrate a Magnesium Zinc Oxide (MZO) based high voltage thin film transistor (HVTFT) built on a transparent glass substrate. The devices are designed with unique ring-type structures and use modulated Mg doping in the channel - gate dielectric interface, resulting in a blocking voltage of over 600 V. In addition to BIPV, the MZO HVTFT based inverter technology also creates new opportunities for emerging self-powered smart glass. PMID:27721484

Fluorination-enabled optimal morphology leads to over 11% efficiency for inverted small-molecule organic solar cells

PubMed Central

Deng, Dan; Zhang, Yajie; Zhang, Jianqi; Wang, Zaiyu; Zhu, Lingyun; Fang, Jin; Xia, Benzheng; Wang, Zhen; Lu, Kun; Ma, Wei; Wei, Zhixiang

2016-01-01

Solution-processable small molecules for organic solar cells have attracted intense attention for their advantages of definite molecular structures compared with their polymer counterparts. However, the device efficiencies based on small molecules are still lower than those of polymers, especially for inverted devices, the highest efficiency of which is <9%. Here we report three novel solution-processable small molecules, which contain π-bridges with gradient-decreased electron density and end acceptors substituted with various fluorine atoms (0F, 1F and 2F, respectively). Fluorination leads to an optimal active layer morphology, including an enhanced domain purity, the formation of hierarchical domain size and a directional vertical phase gradation. The optimal morphology balances charge separation and transfer, and facilitates charge collection. As a consequence, fluorinated molecules exhibit excellent inverted device performance, and an average power conversion efficiency of 11.08% is achieved for a two-fluorine atom substituted molecule. PMID:27991486

Meiotic segregation analysis in spermatozoa of pericentric inversion carriers using fluorescence in-situ hybridization.

PubMed

Morel, F; Laudier, B; Guérif, F; Couet, M L; Royère, D; Roux, C; Bresson, J L; Amice, V; De Braekeleer, M; Douet-Guilbert, N

2007-01-01

Pericentric inversions are structural chromosomal abnormalities resulting from two breaks, one on either side of the centromere, within the same chromosome, followed by 180 degrees rotation and reunion of the inverted segment. They can perturb spermatogenesis and lead to the production of unbalanced gametes through the formation of an inversion loop. We report here the analysis of the meiotic segregation in spermatozoa from six pericentric inversion carriers by multicolour fluorescence in-situ hybridization (FISH) and review the literature. The frequencies of the non-recombinant products (inversion or normal chromosomes) were 80% for the inv(20), 91.41% for the inv(12), 99.43% for the inv(2), 68.12% for the inv(1), 97% for the inv(8)(p12q21) and 60.94% for the inv(8)(p12q24.1). The meiotic segregation of 20 pericentric inversions (including ours) is now available. The frequency of unbalanced spermatozoa varies from 0 to 37.85%. The probability of a crossover within the inverted segment is affected by the chromosome and region involved, the length of the inverted segment and the location of the breakpoints. No recombinant chromosomes were produced when the inverted segment involved <30% of the chromosome length (independent of the size of the inverted segment). Between 30 and 50%, few recombinant chromosomes were produced, inducing a slightly increased risk of aneusomy of recombination in the offspring. The risk of aneusomy became very important when the inverted segment was >50% of the chromosome length. Studies on spermatozoa from inversion carriers help in the comprehension of the mechanisms of meiotic segregation. They should be integrated in the genetic exploration of the infertile men to give them a personalized risk assessment of unbalanced spermatozoa.

Inverting the Object of Study: Recalibrating the Frame of Reference in Study Abroad Experiences

ERIC Educational Resources Information Center

Palmer, Norris W.

2015-01-01

This essay is concerned with study abroad experiences as opportunities for student cognitive development, using the interpretive lens of educational psychologist William G. Perry. A standard and often valuable assignment in courses on world religions is a site visit to a religious institution in one's local area. This may concretize otherwise…

The crystal structure of an inverting glycoside hydrolase family 9 exo-β-D-glucosaminidase and the design of glycosynthase.

PubMed

Honda, Yuji; Arai, Sachiko; Suzuki, Kentaro; Kitaoka, Motomitsu; Fushinobu, Shinya

2016-02-15

Exo-β-D-glucosaminidase (EC 3.2.1.165) from Photobacterium profundum (PpGlcNase) is an inverting GH (glycoside hydrolase) belonging to family 9. We have determined the three-dimensional structure of PpGlcNase to describe the first structure-function relationship of an exo-type GH9 glycosidase. PpGlcNase has a narrow and straight active-site pocket, in contrast with the long glycan-binding cleft of a GH9 endoglucanase. This is because PpGlcNase has a long loop, which blocks the position corresponding to subsites -4 to -2 of the endoglucanase. The pocket shape of PpGlcNase explains its substrate preference for a β1,4-linkage at the non-reducing terminus. Asp(139), Asp(143) and Glu(555) in the active site were located near the β-O1 hydroxy group of GlcN (D-glucosamine), with Asp(139) and Asp(143) holding a nucleophilic water molecule for hydrolysis. The D139A, D143A and E555A mutants significantly decreased hydrolytic activity, indicating their essential role. Of these mutants, D139A exclusively exhibited glycosynthase activity using α-GlcN-F (α-D-glucosaminyl fluoride) and GlcN as substrates, to produce (GlcN)2. Using saturation mutagenesis at Asp(139), we obtained D139E as the best glycosynthase. Compared with the wild-type, the hydrolytic activity of D139E was significantly suppressed (<0.1%), and the F(-)-release activity also decreased (<3%). Therefore the glycosynthase activity of D139E was lower than that of glycosynthases created previously from other inverting GHs. Mutation at the nucleophilic water holder is a general strategy for creating an effective glycosynthase from inverting GHs. However, for GH9, where two acidic residues seem to share the catalytic base role, mutation of Asp(139) might inevitably reduce F(-)-release activity. © 2016 Authors; published by Portland Press Limited.

Highly porous drug-eluting structures

PubMed Central

Elsner, Jonathan J.; Kraitzer, Amir; Grinberg, Orly; Zilberman, Meital

2012-01-01

For many biomedical applications, there is need for porous implant materials. The current article focuses on a method for preparation of drug-eluting porous structures for various biomedical applications, based on freeze drying of inverted emulsions. This fabrication process enables the incorporation of any drug, to obtain an “active implant” that releases drugs to the surrounding tissue in a controlled desired manner. Examples for porous implants based on this technique are antibiotic-eluting mesh/matrix structures used for wound healing applications, antiproliferative drug-eluting composite fibers for stent applications and local cancer treatment, and protein-eluting films for tissue regeneration applications. In the current review we focus on these systems. We show that the release profiles of both types of drugs, water-soluble and water-insoluble, are affected by the emulsion's formulation parameters. The former's release profile is affected mainly through the emulsion stability and the resulting porous microstructure, whereas the latter's release mechanism occurs via water uptake and degradation of the host polymer. Hence, appropriate selection of the formulation parameters enables to obtain desired controllable release profile of any bioactive agent, water-soluble or water-insoluble, and also fit its physical properties to the application. PMID:23507890

Research of energy characteristics of frequency-regulated electric drive

NASA Astrophysics Data System (ADS)

Arsentiev, O. V.; Arsentiev, G. O.; Dunaev, M. P.

2018-03-01

The paper considers the urgency of the research problems of the inverter as a part of the frequency converter. Experimental studies on the influence of the nature of the load on the structure of the distribution of power consumption are used. The authors described virtual models, allowing for analysis of changes in the cardinality of the inverter-factor when using it on an active-inductive load. According to the results, there are research conclusions to determine the relationship between the current form in the DC- link constant voltage and the mode of operation of the induction motor.

Is radical surgery of an inverted papilloma of the maxillary sinus obsolete? a case report.

PubMed

Yildirim, Vedat; Pausch, Niels Christian; Halama, Dirk; Lübbers, Heinz-Theo; Yildirim, Ayhan

2016-12-01

Sinonasal inverted papilloma is a locally aggressive tumor arising from the Schneiderian membrane which lines the nasal cavity and paranasal sinuses. Aggressive surgical approaches, such as lateral rhinotomy, were used until recently for complete removal of the inverted papilloma. Currently, endoscopic resection is the gold standard in the treatment of inverted papilloma. However, there are situations that justify an open approach. For example there are studies that report a higher postoperative recurrence rate after endonasal endoscopic resection, particularly in the treatment of recurrent diseases. While endoscopic resection performed by an experienced surgeon is definitely a minimally invasive therapy, an open approach is not necessarily associated with functional and aesthetic disadvantages. This case report describes the treatment of inverted papilloma by an open approach. This has been described before but the new gold standard of endoscopic resection has to be taken into account before any treatment decision is made nowadays. Contrast-enhanced magnetic resonance imaging of the head and neck area was indicated in a 72-year-old white German man who presented with suspected squamous cell carcinoma of his lower lip. Magnetic resonance imaging additionally revealed a 3×2 cm 2 polycyclic arranged mucosal thickening with cystic and solid contrast affine shares at the antral laterocaudal area of his right maxillary sinus, extending from his right lateral nasal wall to his maxillary sinus floor. He received antral polypectomy with medial maxillectomy via a unilateral LeFort I osteotomy approach. His pterygoid plate was preserved. A histological examination demonstrated a tumor composed of hyperplastic squamous epithelium protruding into the stroma (surface epithelial cells grew downward into the underlying supportive tissue), thus producing a grossly convoluted cerebriform appearance. Two weeks later, the patient regained a well-formed maxilla without any restrictions. He has remained disease-free for 25 months following the surgery and surveillance was continued in our tumor clinic. Endoscopic resection of an inverted papilloma continues to be the gold standard. However, some cases require a radical approach. This does not necessarily increase patient morbidity.

An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weichsel, T., E-mail: tim.weichsel@fep.fraunhofer.de; Hartung, U.; Kopte, T.

2014-05-15

An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10{sup 10} cm{sup −3} to 1 × 10{sup 11} cm{sup −3}, when the magnetron plasma is exposed to the magnetic mirror field of themore » ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10{sup 18} atoms/s for aluminum, which meets the demand for the production of a milliampere Al{sup +} ion beam.« less

Seismic gradiometry using ambient seismic noise in an anisotropic Earth

NASA Astrophysics Data System (ADS)

de Ridder, S. A. L.; Curtis, A.

2017-05-01

We introduce a wavefield gradiometry technique to estimate both isotropic and anisotropic local medium characteristics from short recordings of seismic signals by inverting a wave equation. The method exploits the information in the spatial gradients of a seismic wavefield that are calculated using dense deployments of seismic arrays. The application of the method uses the surface wave energy in the ambient seismic field. To estimate isotropic and anisotropic medium properties we invert an elliptically anisotropic wave equation. The spatial derivatives of the recorded wavefield are evaluated by calculating finite differences over nearby recordings, which introduces a systematic anisotropic error. A two-step approach corrects this error: finite difference stencils are first calibrated, then the output of the wave-equation inversion is corrected using the linearized impulse response to the inverted velocity anomaly. We test the procedure on ambient seismic noise recorded in a large and dense ocean bottom cable array installed over Ekofisk field. The estimated azimuthal anisotropy forms a circular geometry around the production-induced subsidence bowl. This conforms with results from studies employing controlled sources, and with interferometry correlating long records of seismic noise. Yet in this example, the results were obtained using only a few minutes of ambient seismic noise.

Face inversion and acquired prosopagnosia reduce the size of the perceptual field of view.

PubMed

Van Belle, Goedele; Lefèvre, Philippe; Rossion, Bruno

2015-03-01

Using a gaze-contingent morphing approach, we asked human observers to choose one of two faces that best matched the identity of a target face: one face corresponded to the reference face's fixated part only (e.g., one eye), the other corresponded to the unfixated area of the reference face. The face corresponding to the fixated part was selected significantly more frequently in the inverted than in the upright orientation. This observation provides evidence that face inversion reduces an observer's perceptual field of view, even when both upright and inverted faces are displayed at full view and there is no performance difference between these conditions. It rules out an account of the drop of performance for inverted faces--one of the most robust effects in experimental psychology--in terms of a mere difference in local processing efficiency. A brain-damaged patient with pure prosopagnosia, viewing only upright faces, systematically selected the face corresponding to the fixated part, as if her perceptual field was reduced relative to normal observers. Altogether, these observations indicate that the absence of visual knowledge reduces the perceptual field of view, supporting an indirect view of visual perception. Copyright © 2014 Elsevier B.V. All rights reserved.

Improving Student Success in Calculus: A Comparison of Four College Calculus Classes

NASA Astrophysics Data System (ADS)

Bagley, Spencer Franklin

The quality of education in science, technology, engineering, and mathematics (STEM) fields is an issue of particular educational and economic importance, and Calculus I is a linchpin course in STEM major tracks. A national study is currently being conducted examining the characteristics of successful programs in college calculus (CSPCC, 2012). In work related to the CSPCC program, this study examines the effects on student outcomes of four different teaching strategies used at a single institution. The four classes were a traditional lecture, a lecture with discussion, a lecture incorporating both discussion and technology, and an inverted model. This dissertation was guided by three questions: (1) What impact do these four instructional approaches have on students' persistence, beliefs about mathematics, and conceptual and procedural achievement in calculus? (2) How do students at the local institution compare to students in the national database? And (3) How do the similarities and differences in opportunities for learning presented in the four classes contribute to the similarities and differences in student outcomes? Quantitative analysis of surveys and exams revealed few statistically significant differences in outcomes, and students in the inverted classroom often had poorer outcomes than those in other classes. Students in the technology-enhanced class scored higher on conceptual items on the final exam than those in other classes. Comparing to the national database, local students had similar switching rates but less expert-like attitudes and beliefs about mathematics than the national average. Qualitative analysis of focus group interviews, classroom observations, and student course evaluations showed that several implementation issues, some the result of pragmatic constraints, others the result of design choice, weakened affordances provided by innovative features and shrunk the differences between classes. There were substantial differences between the inverted classroom in this study and successful implementations in the literature. I identified a set of departures that forms a list of best practices for inverting classrooms. Students in all classes felt that prior calculus experience was a prerequisite for their current calculus class, and that class sessions felt rushed. These concerns implicate the constraints imposed by the curriculum shared by the four classes.

P wave crustal velocity structure in the greater Mount Rainier area from local earthquake tomography

USGS Publications Warehouse

Moran, S.C.; Lees, J.M.; Malone, S.D.

1999-01-01

We present results from a local earthquake tomographic imaging experiment in the greater Mount Rainier area. We inverted P wave arrival times from local earthquakes recorded at permanent and temporary Pacific Northwest Seismograph Network seismographs between 1980 and 1996. We used a method similar to that described by Lees and Crosson [1989], modified to incorporate the parameter separation method for decoupling the hypocenter and velocity problems. In the upper 7 km of the resulting model there is good correlation between velocity anomalies and surface geology. Many focal mechanisms within the St. Helens seismic zone have nodal planes parallel to the epicentral trend as well as to a north-south trending low-velocity trough, leading us to speculate that the trough represents a zone of structural weakness in which a moderate (M 6.5-7.0) earthquake could occur. In contrast, the western Rainier seismic zone does not correlate in any simple way with anomaly patterns or focal mechanism fault planes, leading us to infer that it is less likely to experience a moderate earthquake. A ???10 km-wide low-velocity anomaly occurs 5 to 18 km beneath the summit of Mount Rainier, which we interpret to be a signal of a region composed of hot, fractured rock with possible small amounts of melt or fluid. No systematic velocity pattern is observed in association with the southern Washington Cascades conductor. A midcrustal anomaly parallels the Olympic-Wallowa lineament as well as several other geophysical trends, indicating that it may play an important role in regional tectonics. Copyright 1999 by the American Geophysical Union.

The properties of borderlines in discontinuous conservative systems

NASA Astrophysics Data System (ADS)

Wang, X.-M.; Fang, Z.-J.

2006-02-01

The properties of the set of borderline images in discontinuous conservative systems are commonly investigated. The invertible system in which a stochastic web was found in 1999 is re-discussed here. The result shows that the set of images of the borderline actually forms the same stochastic web. The web has two typical local fine structures. Firstly, in some parts of the web the borderline crosses the manifold of hyperbolic points so that the chaotic diffusion is damped greatly; secondly, in other parts of phase space many holes and elliptic islands appear in the stochastic layer. This local structure shows infinite self-similarity. The noninvertible system in which the so-called chaotic quasi-attractor was found in [X.-M. Wang et al., Eur. Phys. J. D 19, 119 (2002)] is also studied here. The numerical investigation shows that such a chaotic quasi-attractor is confined by the preceding lower order images of the borderline. The mechanism of this confinement is revealed: a forbidden zone exists that any orbit can not visit, which is the sub-phase space of one side of the first image of the borderline. Each order of the images of the forbidden zone can be qualitatively divided into two sub-phase regions: one is the so-called escaping region that provides the orbit with an escaping channel, the other is the so-called dissipative region where the contraction of phase space occurs.

Deep convective clouds at the tropopause

NASA Astrophysics Data System (ADS)

Aumann, H. H.; Desouza-Machado, S. G.

2010-07-01

Data from the Advanced Infrared Sounder (AIRS) on the EOS Aqua spacecraft identify thousands of cloud tops colder than 225 K, loosely referred to as Deep Convective Clouds (DCC). Many of these cloud tops have "inverted" spectra, i.e. areas of strong water vapor, CO2 and ozone opacity, normally seen in absorption, are now seen in emission. We refer to these inverted spectra as DCCi. They are found in about 0.4% of all spectra from the tropical oceans excluding the Western Tropical Pacific (WTP), 1.1% in the WTP. The cold clouds are the anvils capping thunderstorms and consist of optically thick cirrus ice clouds. The precipitation rate associated with DCCi suggests that imbedded in these clouds, protruding above them, and not spatially resolved by the AIRS 15 km FOV, are even colder bubbles, where strong convection pushes clouds to within 5 hPa of the pressure level of the tropopause cold point. Associated with DCCi is a local upward displacement of the tropopause, a cold "bulge", which can be seen directly in the brightness temperatures of AIRS and AMSU channels with weighting function peaking between 40 and 2 hPa, without the need for a formal temperature retrieval. The bulge is not resolved by the analysis in numerical weather prediction models. The locally cold cloud tops relative to the analysis give the appearance (in the sense of an "illusion") of clouds overshooting the tropopause and penetrating into the stratosphere. Based on a simple model of optically thick cirrus clouds, the spectral inversions seen in the AIRS data do not require these clouds to penetrate into the stratosphere. However, the contents of the cold bulge may be left in the lower stratosphere as soon as the strong convection subsides. The heavy precipitation and the distortion of the temperature structure near the tropopause indicate that DCCi are associated with intense storms. Significant long-term trends in the statistical properties of DCCi could be interesting indicators of climate change.

Upper Crustal Structure of Taiwan Constrained by the Ellipticity of the Noise-derived Rayleigh Waves

NASA Astrophysics Data System (ADS)

Chien, C. C.; Chen, Y. N.; Gung, Y.; Liang, W. T.

2016-12-01

In the last decade, the noise interferometry has been a popular technique, and widely applied to constraint the crust and uppermost mantle structure, bringing in revolutionary resolution in area with dense seismic network, including Taiwan. However, limited by the available frequency band of the noise-derived surface waves, the near surface (<5km) structure is much less resolved as compared to the rest of the crust in Taiwan. Such limitation may be lifted by using the ZH ratio of Rayleigh waves, because, for the same period, the ZH ratio of Rayleigh waves is much more sensitive to the shallower structure than those provided by the corresponding phase or group velocities. In this study, aiming to better constraint the seismic structure of the shallow crust of Taiwan, we measure the ZH ratios of the Rayleigh waves derived by noise interferometry. Continuous records from two major seismic networks in Taiwan are used. In total, data from 63 short period stations and 48 broadband stations are used to derived the four combinations (ZZ, ZR, RZ, RR) of cross-correlation functions (CCF). We then measure the ZH ratios of the derived Rayleigh waves. We present the measured results, invert for the local 1-D structure for sites with stable measurements. We then compare the results with the published tomographic models and discuss their geological implications.

Moment-tensor inversion for offshore earthquakes east of Taiwan and their implications to regional collision

NASA Astrophysics Data System (ADS)

Kao, Honn; Jian, Pei-Ru; Ma, Kuo-Fong; Huang, Bor-Shouh; Liu, Chun-Chi

Reliable determination of source parameters for offshore earthquakes east of Taiwan with mb<5.5 was a difficult task because of the poor azimuthal coverage by local network and the lack of signals at teleseismic distances. We take advantage of the recently established “Broadband Array in Taiwan for Seismology” (BATS) to invert seismic moment tensors for 7 such events occurred in 1996. To cope with different patterns of background noise and unknown structural details, we utilize variable frequency bands in the inversion and adapt a two-step procedure to select best velocity models for individual epicenter-station paths. Our results are consistent with the overall patterns of regional collision and indicate that the resulting compressive stress has caused significant intraplate deformation within the Philippine Sea plate. Simulation of the region's geological evolution and orogenic processes should take this factor into account and allow the Philippine Sea plate to deform internally.

Enhanced Andreev reflection in gapped graphene

NASA Astrophysics Data System (ADS)

Majidi, Leyla; Zareyan, Malek

2012-08-01

We theoretically demonstrate unusual features of superconducting proximity effect in gapped graphene that presents a pseudospin symmetry-broken ferromagnet with a net pseudomagnetization. We find that the presence of a band gap makes the Andreev conductance of graphene superconductor/pseudoferromagnet (S/PF) junction to behave similar to that of a graphene ferromagnet-superconductor junction. The energy gap ΔN can enhance the pseudospin inverted Andreev conductance of S/PF junction to reach a limiting maximum value for ΔN≫μ, which depending on the bias voltage can be larger than the value for the corresponding junction with no energy gap. We further demonstrate a damped-oscillatory behavior for the local density of states of the PF region of S/PF junction and a long-range crossed Andreev reflection process in PF/S/PF structure with antiparallel alignment of pseudomagnetizations of PFs, which confirm that, in this respect, the gapped normal graphene behaves like a ferromagnetic graphene.

Two-dimensional AXUV-based radiated power density diagnostics on NSTX-Ua)

NASA Astrophysics Data System (ADS)

Faust, I.; Delgado-Aparicio, L.; Bell, R. E.; Tritz, K.; Diallo, A.; Gerhardt, S. P.; LeBlanc, B.; Kozub, T. A.; Parker, R. R.; Stratton, B. C.

2014-11-01

A new set of radiated-power-density diagnostics for the National Spherical Torus Experiment Upgrade (NSTX-U) tokamak have been designed to measure the two-dimensional poloidal structure of the total photon emissivity profile in order to perform power balance, impurity transport, and magnetohydrodynamic studies. Multiple AXUV-diode based pinhole cameras will be installed in the same toroidal angle at various poloidal locations. The local emissivity will be obtained from several types of tomographic reconstructions. The layout and response expected for the new radially viewing poloidal arrays will be shown for different impurity concentrations to characterize the diagnostic sensitivity. The radiated power profile inverted from the array data will also be used for estimates of power losses during transitions from various divertor configurations in NSTX-U. The effect of in-out and top/bottom asymmetries in the core radiation from high-Z impurities will be addressed.

Two-dimensional AXUV-based radiated power density diagnostics on NSTX-U.

PubMed

Faust, I; Delgado-Aparicio, L; Bell, R E; Tritz, K; Diallo, A; Gerhardt, S P; LeBlanc, B; Kozub, T A; Parker, R R; Stratton, B C

2014-11-01

A new set of radiated-power-density diagnostics for the National Spherical Torus Experiment Upgrade (NSTX-U) tokamak have been designed to measure the two-dimensional poloidal structure of the total photon emissivity profile in order to perform power balance, impurity transport, and magnetohydrodynamic studies. Multiple AXUV-diode based pinhole cameras will be installed in the same toroidal angle at various poloidal locations. The local emissivity will be obtained from several types of tomographic reconstructions. The layout and response expected for the new radially viewing poloidal arrays will be shown for different impurity concentrations to characterize the diagnostic sensitivity. The radiated power profile inverted from the array data will also be used for estimates of power losses during transitions from various divertor configurations in NSTX-U. The effect of in-out and top/bottom asymmetries in the core radiation from high-Z impurities will be addressed.

Orogenic front propagation in the basement involved Malargüe fold and thrust belt, Neuquén Basin, (Argentina)

NASA Astrophysics Data System (ADS)

Branellec, Matthieu; Nivière, Bertrand; Callot, Jean-Paul; Ringenbach, Jean-Claude

2015-04-01

The Malargüe fold and thrust belt (MFTB) and the San Rafael Block (SRB) are located in the northern termination of the Neuquén basin in Argentina. This basin is a wide inverted intracratonic sag basin with polyphased evolution controlled at large scale by the dynamic of the Pacific subduction. By late Triassic times, narrow rift basins developed and evolved toward a sag basin from middle Jurassic to late Cretaceous. From that time on, compression at the trench resulted in various shortening pulses in the back-arc area. Here we aim to analyze the Andean system at 35°S by comparing the Miocene structuration in the MFTB and the current deformation along the oriental border or the San Rafael Block. The main structuration stage in the MFTB occurred by Miocene times (15 to 10 Ma) producing the principal uplift of the Andean Cordillera. As shown by new structural cross sections, Triassic-early Jurassic rift border faults localized the Miocene compressive tectonics. Deformation is compartmentalized and does not exhibit a classical propagation of homogeneous deformation sequence expected from the critical taper theory. Several intramontane basins in the hangingwall of the main thrusts progressively disconnected from the foreland. In addition, active tectonics has been described in the front of the MFTB attesting for the on-going compression in this area. 100 km farther to the east, The San Rafael Block, is separated from the MFTB by the Rio Grande basin. The SRB is mostly composed of Paleozoic terranes and Triassic rift-related rocks, overlain by late Miocene synorogenic deposits. The SRB is currently uplifted along its oriental border along several active faults. These faults have clear morphologic signatures in Quaternary alluvial terraces and folded Pleistocene lavas. As in the MFTB, the active deformation localization remains localized by structural inheritance. The Andean system is thus evolving as an atypical orogenic wedge partly by frontal accretion at the front of the belt and by migration and localization of strain far from the front leading to crustal block reactivation.

An unusual internal ribosomal entry site of inverted symmetry directs expression of a potato leafroll polerovirus replication-associated protein

PubMed Central

Jaag, Hannah Miriam; Kawchuk, Lawrence; Rohde, Wolfgang; Fischer, Rainer; Emans, Neil; Prüfer, Dirk

2003-01-01

Potato leafroll polerovirus (PLRV) genomic RNA acts as a polycistronic mRNA for the production of proteins P0, P1, and P2 translated from the 5′-proximal half of the genome. Within the P1 coding region we identified a 5-kDa replication-associated protein 1 (Rap1) essential for viral multiplication. An internal ribosome entry site (IRES) with unusual structure and location was identified that regulates Rap1 translation. Core structural elements for internal ribosome entry include a conserved AUG codon and a downstream GGAGAGAGAGG motif with inverted symmetry. Reporter gene expression in potato protoplasts confirmed the internal ribosome entry function. Unlike known IRES motifs, the PLRV IRES is located completely within the coding region of Rap1 at the center of the PLRV genome. PMID:12835413

Automatic control in multidrive electrotechnical complexes with semiconductor converters

NASA Astrophysics Data System (ADS)

Vasilev, B. U.; Mardashov, D. V.

2017-01-01

The frequency convertor and the automatic control system, which can be used in the multi-drive electromechanical system with a few induction motions, are considered. The paper presents the structure of existing modern multi-drive electric drives inverters, namely, electric drives with a total frequency converter and few electric motions, and an electric drive, in which the converter is used for power supply and control of the independent frequency. It was shown that such technical solutions of frequency converters possess a number of drawbacks. The drawbacks are given. It was shown that the control of technological processes using the electric drive of this structure may be provided under very limited conditions, as the energy efficiency and the level of electromagnetic compatibility of electric drives is low. The authors proposed using a multi-inverter structure with an active rectifier in multidrive electric drives with induction motors frequency converters. The application of such frequency converter may solve the problem of electromagnetic compatibility, namely, consumption of sinusoidal currents from the network and the maintenance of a sinusoidal voltage and energy compatibility, namely, consumption of practically active energy from the network. Also, the paper proposes the use of the automatic control system, which by means of a multi-inverter frequency converter provides separate control of drive machines and flexible regulation of technological processes. The authors present oscillograms, which confirm the described characteristics of the developed electrical drive. The possible subsequent ways to improve the multi-motor drives are also described.

Strand invasion structures in the inverted repeat of Candida albicans mitochondrial DNA reveal a role for homologous recombination in replication.

PubMed

Gerhold, Joachim M; Aun, Anu; Sedman, Tiina; Jõers, Priit; Sedman, Juhan

2010-09-24

Molecular recombination and transcription are proposed mechanisms to initiate mitochondrial DNA (mtDNA) replication in yeast. We conducted a comprehensive analysis of mtDNA from the yeast Candida albicans. Two-dimensional agarose gel electrophoresis of mtDNA intermediates reveals no bubble structures diagnostic of specific replication origins, but rather supports recombination-driven replication initiation of mtDNA in yeast. Specific species of Y structures together with DNA copy number analyses of a C. albicans mutant strain provide evidence that a region in a mainly noncoding inverted repeat is predominantly involved in replication initiation via homologous recombination. Our further findings show that the C. albicans mtDNA forms a complex branched network that does not contain detectable amounts of circular molecules. We provide topological evidence for recombination-driven mtDNA replication initiation and introduce C. albicans as a suitable model organism to study wild-type mtDNA maintenance in yeast. Copyright © 2010 Elsevier Inc. All rights reserved.

Fabrication and characterization of cerium-doped barium titanate inverse opal by sol-gel method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin Yi; Zhu Yihua; Yang Xiaoling

Cerium-doped barium titanate inverted opal was synthesized from barium acetate contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a polystyrene (PS) opal. This procedure involves infiltration of precursors into the interstices of the PS opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the PS opal by calcination. The morphologies of opal and inverse opal were characterized by scanning electron microscope (SEM). The pores were characterized by mercury intrusion porosimetry (MIP). X-ray photoelectron spectroscopy (XPS) investigation showed the doping structure of cerium, barium and titanium. And powder X-ray diffraction allowsmore » one to observe the influence of doping degree on the grain size. The lattice parameters, crystal size and lattice strain were calculated by the Rietveld refinement method. The synthesis of cerium-doped barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three-dimensional photonic crystal devices. - Graphical abstract: Cerium-doped barium titanate inverted opal was synthesized from barium acetate acid contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a PS opal, which involves infiltration of precursors into the interstices of the PS opal template and removal of the PS opal by calcination.« less

Designing an Inverter-based Operational Transconductance Amplifier-capacitor Filter with Low Power Consumption for Biomedical Applications

PubMed Central

Yousefinezhad, Sajad; Kermani, Saeed; Hosseinnia, Saeed

2018-01-01

The operational transconductance amplifier-capacitor (OTA-C) filter is one of the best structures for implementing continuous-time filters. It is particularly important to design a universal OTA-C filter capable of generating the desired filter response via a single structure, thus reducing the filter circuit power consumption as well as noise and the occupied space on the electronic chip. In this study, an inverter-based universal OTA-C filter with very low power consumption and acceptable noise was designed with applications in bioelectric and biomedical equipment for recording biomedical signals. The very low power consumption of the proposed filter was achieved through introducing bias in subthreshold MOSFET transistors. The proposed filter is also capable of simultaneously receiving favorable low-, band-, and high-pass filter responses. The performance of the proposed filter was simulated and analyzed via HSPICE software (level 49) and 180 nm complementary metal-oxide-semiconductor technology. The rate of power consumption and noise obtained from simulations are 7.1 nW and 10.18 nA, respectively, so this filter has reduced noise as well as power consumption. The proposed universal OTA-C filter was designed based on the minimum number of transconductance blocks and an inverter circuit by three transconductance blocks (OTA). PMID:29535925

Metamorphic III–V Solar Cells: Recent Progress and Potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Ivan; France, Ryan M.; Geisz, John F.

Inverted metamorphic multijunction solar cells have been demonstrated to be a pathway to achieve the highest photovoltaic (PV) conversion efficiencies. Attaining high-quality lattice-mismatched (metamorphic) semiconductor devices is challenging. However, recent improvements to compositionally graded buffer epitaxy and junction structures have led to the achievement of high-quality metamorphic solar cells exhibiting internal luminescence efficiencies over 90%. For this high material quality, photon recycling is significant, and therefore, the optical environment of the solar cell becomes important. In this paper, we first present recent progress and performance results for 1- and 0.7-eV GaInAs solar cells grown on GaAs substrates. Then, an electroopticalmore » model is used to assess the potential performance improvements in current metamorphic solar cells under different realizable design scenarios. The results show that the quality of 1-eV subcells is such that further improving its electronic quality does not produce significant Voc increases in the four-junction inverted metamorphic subcells, unless a back reflector is used to enhance photon recycling, which would significantly complicate the structure. Conversely, improving the electronic quality of the 0.7-eV subcell would lead to significant Voc boosts, driving the progress of four-junction inverted metamorphic solar cells.« less

Designing an Inverter-based Operational Transconductance Amplifier-capacitor Filter with Low Power Consumption for Biomedical Applications.

PubMed

Yousefinezhad, Sajad; Kermani, Saeed; Hosseinnia, Saeed

2018-01-01

The operational transconductance amplifier-capacitor (OTA-C) filter is one of the best structures for implementing continuous-time filters. It is particularly important to design a universal OTA-C filter capable of generating the desired filter response via a single structure, thus reducing the filter circuit power consumption as well as noise and the occupied space on the electronic chip. In this study, an inverter-based universal OTA-C filter with very low power consumption and acceptable noise was designed with applications in bioelectric and biomedical equipment for recording biomedical signals. The very low power consumption of the proposed filter was achieved through introducing bias in subthreshold MOSFET transistors. The proposed filter is also capable of simultaneously receiving favorable low-, band-, and high-pass filter responses. The performance of the proposed filter was simulated and analyzed via HSPICE software (level 49) and 180 nm complementary metal-oxide-semiconductor technology. The rate of power consumption and noise obtained from simulations are 7.1 nW and 10.18 nA, respectively, so this filter has reduced noise as well as power consumption. The proposed universal OTA-C filter was designed based on the minimum number of transconductance blocks and an inverter circuit by three transconductance blocks (OTA).

Three-Dimensional Flexible Complementary Metal-Oxide-Semiconductor Logic Circuits Based On Two-Layer Stacks of Single-Walled Carbon Nanotube Networks.

PubMed

Zhao, Yudan; Li, Qunqing; Xiao, Xiaoyang; Li, Guanhong; Jin, Yuanhao; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan

2016-02-23

We have proposed and fabricated stable and repeatable, flexible, single-walled carbon nanotube (SWCNT) thin film transistor (TFT) complementary metal-oxide-semiconductor (CMOS) integrated circuits based on a three-dimensional (3D) structure. Two layers of SWCNT-TFT devices were stacked, where one layer served as n-type devices and the other one served as p-type devices. On the basis of this method, it is able to save at least half of the area required to construct an inverter and make large-scale and high-density integrated CMOS circuits easier to design and manufacture. The 3D flexible CMOS inverter gain can be as high as 40, and the total noise margin is more than 95%. Moreover, the input and output voltage of the inverter are exactly matched for cascading. 3D flexible CMOS NOR, NAND logic gates, and 15-stage ring oscillators were fabricated on PI substrates with high performance as well. Stable electrical properties of these circuits can be obtained with bending radii as small as 3.16 mm, which shows that such a 3D structure is a reliable architecture and suitable for carbon nanotube electrical applications in complex flexible and wearable electronic devices.

Inverted papillomas and benign nonneoplastic lesions of the nasal cavity

PubMed Central

Casiano, Roy R.

2012-01-01

Background: Benign lesions of the nasal cavity represent a diverse group of pathologies. Furthermore, each of these disorders may present differently in any given patient as pain and discomfort, epistaxis, headaches, vision changes, or nasal obstruction. Although these nasal masses are benign, many of them have a significant capacity for local tissue destruction and symptomatology secondary to this destruction. Advances in office-based endoscopic nasendoscopy have equipped the otolaryngologist with a safe, inexpensive, and rapid means of directly visualizing lesions within the nasal cavity and the initiation of appropriate treatment. Methods: The purpose of this study is to review the diagnosis, management, and controversies of many of the most common benign lesions of the nasal cavity encountered by the primary care physician or otolaryngologist. Results: This includes discussion of inverted papilloma (IP), juvenile angiofibroma, squamous papilloma, pyogenic granuloma, hereditary hemorrhagic telangiectasia, schwannoma, benign fibro-osseous lesions, and other benign lesions of the nasal cavity, with particular emphasis on IP and juvenile angiofibroma. Conclusion: A diverse array of benign lesions occur within the nasal cavity and paranasal cavities. Despite their inability to metastasize, many of these lesions have significant capability for local tissue destruction and recurrence. PMID:22487294

Numerical simulations of heat transfer distribution of a two-pass square channel with V-rib turbulator and bleed holes

NASA Astrophysics Data System (ADS)

Kumar, Sourabh; Amano, R. S.; Lucci, Jose Martinez

2013-08-01

The blade tip region in gas turbine encounters high thermal loads due to temperature difference and hence efforts for high durability and safe operations are essential. Improved and robust methods of cooling are required to downgrade heat transfer rate to turbine blades. The blade tip regions, which are exposed to high gas flow, suffers high local thermal load which are due to external tip leakage. Jet impingement, pin cooling etc. are techniques used for cooling blades. A more usual way is to use serpentine passage with 180-degree turn. In this study, numerical simulation of heat transfer distribution of a two-pass square channel with rib turbulators and bleed holes were done. Periodical rib turbulators and bleed holes were used in the channel. The ribs arrangement were 60 degree V rib, 60 degree inverted V ribs, combination of 60 degree V rib at inlet and 60 inverted V rib at outlet section and combination of Inverted V at inlet and V rib at the outlet. The results were numerically computed using Fluent with Reynolds number of 12,500 and 28,500. Turbulence models used for computations were k-ω-SST and RSM. Temperature based and shear stress based techniques were used for heat transfer distribution prediction. The results for 60 degree V rib, 60 degree inverted V ribs were compared with the experimental results for validation of the results obtained. Detailed distribution shows distinctive peaks in heat transfer around bleed holes and rib turbulator. Comparisons of the overall performance of the models with different orientation of rib turbulator are presented. It is found that due to the combination of 60 degree inverted V rib in inlet and 60 V rib in outlet with bleed holes provides better heat treatment. It is suggested that the use of rib turbulator with bleed holes provides suitable for augmenting blade cooling to achieve an optimal balance between thermal and mechanical design requirements.

Three-dimensional Crustal Structure beneath the Tibetan Plateau Revealed by Multi-scale Gravity Analysis

NASA Astrophysics Data System (ADS)

Xu, C.; Luo, Z.; Sun, R.; Li, Q.

2017-12-01

The Tibetan Plateau, the largest and highest plateau on Earth, was uplifted, shorten and thicken by the collision and continuous convergence of the Indian and Eurasian plates since 50 million years ago, the Eocene epoch. Fine three-dimensional crustal structure of the Tibetan Plateau is helpful in understanding the tectonic development. At present, the ordinary method used for revealing crustal structure is seismic method, which is inhibited by poor seismic station coverage, especially in the central and western plateau primarily due to the rugged terrain. Fortunately, with the implementation of satellite gravity missions, gravity field models have demonstrated unprecedented global-scale accuracy and spatial resolution, which can subsequently be employed to study the crustal structure of the entire Tibetan Plateau. This study inverts three-dimensional crustal density and Moho topography of the Tibetan Plateau from gravity data using multi-scale gravity analysis. The inverted results are in agreement with those provided by the previous works. Besides, they can reveal rich tectonic development of the Tibetan Plateau: (1) The low-density channel flow can be observed from the inverted crustal density; (2) The Moho depth in the west is deeper than that in the east, and the deepest Moho, which is approximately 77 km, is located beneath the western Qiangtang Block; (3) The Moho fold, the directions of which are in agreement with the results of surface movement velocities estimated from Global Positioning System, exists clearly on the Moho topography.This study is supported by the National Natural Science Foundation of China (Grant No. 41504015), the China Postdoctoral Science Foundation (Grant No. 2015M572146), and the Surveying and Mapping Basic Research Programme of the National Administration of Surveying, Mapping and Geoinformation (Grant No. 15-01-08).

Ureaplasma antigenic variation beyond MBA phase variation: DNA inversions generating chimeric structures and switching in expression of the MBA N-terminal paralogue UU172

PubMed Central

Zimmerman, Carl-Ulrich R; Rosengarten, Renate; Spergser, Joachim

2011-01-01

Phase variation of the major ureaplasma surface membrane protein, the multiple-banded antigen (MBA), with its counterpart, the UU376 protein, was recently discussed as a result of DNA inversion occurring at specific inverted repeats. Two similar inverted repeats to the ones within the mba locus were found in the genome of Ureaplasma parvum serovar 3; one within the MBA N-terminal paralogue UU172 and another in the adjacent intergenic spacer region. In this report, we demonstrate on both genomic and protein level that DNA inversion at these inverted repeats leads to alternating expression between UU172 and the neighbouring conserved hypothetical ORF UU171. Sequence analysis of this phase-variable ‘UU172 element’ from both U. parvum and U. urealyticum strains revealed that it is highly conserved among both species and that it also includes the orthologue of UU144. A third inverted repeat region in UU144 is proposed to serve as an additional potential inversion site from which chimeric genes can evolve. Our results indicate that site-specific recombination events in the genome of U. parvum serovar 3 are dynamic and frequent, leading to a broad spectrum of antigenic variation by which the organism may evade host immune responses. PMID:21255110

Evolution of short inverted repeat in cupressophytes, transfer of accD to nucleus in Sciadopitys verticillata and phylogenetic position of Sciadopityaceae.

PubMed

Li, Jia; Gao, Lei; Chen, Shanshan; Tao, Ke; Su, Yingjuan; Wang, Ting

2016-02-11

Sciadopitys verticillata is an evergreen conifer and an economically valuable tree used in construction, which is the only member of the family Sciadopityaceae. Acquisition of the S. verticillata chloroplast (cp) genome will be useful for understanding the evolutionary mechanism of conifers and phylogenetic relationships among gymnosperm. In this study, we have first reported the complete chloroplast genome of S. verticillata. The total genome is 138,284 bp in length, consisting of 118 unique genes. The S. verticillata cp genome has lost one copy of the canonical inverted repeats and shown distinctive genomic structure comparing with other cupressophytes. Fifty-three simple sequence repeat loci and 18 forward tandem repeats were identified in the S. verticillata cp genome. According to the rearrangement of cupressophyte cp genome, we proposed one mechanism for the formation of inverted repeat: tandem repeat occured first, then rearrangement divided the tandem repeat into inverted repeats located at different regions. Phylogenetic estimates inferred from 59-gene sequences and cpDNA organizations have both shown that S. verticillata was sister to the clade consisting of Cupressaceae, Taxaceae, and Cephalotaxaceae. Moreover, accD gene was found to be lost in the S. verticillata cp genome, and a nucleus copy was identified from two transcriptome data.

Traveltime inversion and error analysis for layered anisotropy

NASA Astrophysics Data System (ADS)

Jiang, Fan; Zhou, Hua-wei

2011-02-01

While tilted transverse isotropy (TTI) is a good approximation of the velocity structure for many dipping and fractured strata, it is still challenging to estimate anisotropic depth models even when the tilted angle is known. With the assumption of weak anisotropy, we present a TTI traveltime inversion approach for models consisting of several thickness-varying layers where the anisotropic parameters are constant for each layer. For each model layer the inversion variables consist of the anisotropic parameters ɛ and δ, the tilted angle φ of its symmetry axis, layer velocity along the symmetry axis, and thickness variation of the layer. Using this method and synthetic data, we evaluate the effects of errors in some of the model parameters on the inverted values of the other parameters in crosswell and Vertical Seismic Profile (VSP) acquisition geometry. The analyses show that the errors in the layer symmetry axes sensitively affect the inverted values of other parameters, especially δ. However, the impact of errors in δ on the inversion of other parameters is much less than the impact on δ from the errors in other parameters. Hence, a practical strategy is first to invert for the most error-tolerant parameter layer velocity, then progressively invert for ɛ in crosswell geometry or δ in VSP geometry.

Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications

PubMed Central

Vidor, Fábio F.; Meyers, Thorsten; Hilleringmann, Ulrich

2016-01-01

Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs) are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high-k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the ION/IOFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V/V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates. PMID:28335282

Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications.

PubMed

Vidor, Fábio F; Meyers, Thorsten; Hilleringmann, Ulrich

2016-08-23

Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs) are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high- k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the I ON / I OFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V / V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates.

Overload protection system for power inverter

NASA Technical Reports Server (NTRS)

Nagano, S. (Inventor)

1977-01-01

An overload protection system for a power inverter utilized a first circuit for monitoring current to the load from the power inverter to detect an overload and a control circuit to shut off the power inverter, when an overload condition was detected. At the same time, a monitoring current inverter was turned on to deliver current to the load at a very low power level. A second circuit monitored current to the load, from the monitoring current inverter, to hold the power inverter off through the control circuit, until the overload condition was cleared so that the control circuit may be deactivated in order for the power inverter to be restored after the monitoring current inverter is turned off completely.

Seismic imaging of the geothermal area in Tarutung (Sumatra, Indonesia): Comparison of local earthquake and ambient noise tomography

NASA Astrophysics Data System (ADS)

Muksin, Muksin; Bauer, Klaus; Haberland, Christian; Ryberg, Trond

2013-04-01

A joint German-Indonesian research initiative is conducted to support the geothermal energy development in Indonesia, where one important aspect is exploration technology. An almost unexplored region located in northern Sumatra (Indonesia) was chosen to develop and demonstrate an integrated exploration strategy which includes structural geology, active seismics, passive seismology, and magnetotelluric investigations. The geothermal potential at this site is mainly determined by the Sumatran fault system and its interplay with young volcanism associated with subduction zone processes. Within the passive seismology study, a temporary network of 42 stations was installed around the city of Tarutung running over a period of 10 month from May 2011 until February 2012. The Sumatran fault was covered at the center of the network, and stations were distributed within a radius of 20 km with spacings of about 5 km on average. The collected data allow for the 3D imaging of seismic velocities and intrinsic attenuation, high resolution relocalisation of seismicity, determination of fault plane solutions, and analysis of ambient noise generated surface waves. The general objective is to integrate the final results with other geoscientific data and interpretations and to develop a conceptual model for the geothermal system of the target region. In the presentation we will focuss on a comparison of local earthquake tomography and ambient noise surface wave inversion. We applied HYPO71 to locate events and found 2,586 events within the network and relocate 809 events having gap angle less than 180 degrees by using VELEST and determined the 1D Vp and Vp/Vs models forming the starting models of the subsequent 3D inversion. SIMUL2000 code was used to invert for Vp and Vp/Vs as well as the intrinsic attenuation for P waves (Qp). For the ambient noise tomography we cross-correlated the daily vertical component recordings for all available station pairs in the 40 station array. Surface wave travel times were picked and inverted using the Fast Marching Surface-wave Tomography (FMST) method. The Vp structure images the geometry of the basins while high Vp/Vs and low Qp are associated with hot fluid pathway originated below the Sumatran fault. We examine the comparison of the results of the Vp/Vs and Qp with the ambient noise tomography to investigate the potential for combining both approach to study geothermal systems.

Multiple attractors and boundary crises in a tri-trophic food chain.

PubMed

Boer, M P; Kooi, B W; Kooijman, S A

2001-02-01

The asymptotic behaviour of a model of a tri-trophic food chain in the chemostat is analysed in detail. The Monod growth model is used for all trophic levels, yielding a non-linear dynamical system of four ordinary differential equations. Mass conservation makes it possible to reduce the dimension by 1 for the study of the asymptotic dynamic behaviour. The intersections of the orbits with a Poincaré plane, after the transient has died out, yield a two-dimensional Poincaré next-return map. When chaotic behaviour occurs, all image points of this next-return map appear to lie close to a single curve in the intersection plane. This motivated the study of a one-dimensional bi-modal, non-invertible map of which the graph resembles this curve. We will show that the bifurcation structure of the food chain model can be understood in terms of the local and global bifurcations of this one-dimensional map. Homoclinic and heteroclinic connecting orbits and their global bifurcations are discussed also by relating them to their counterparts for a two-dimensional map which is invertible like the next-return map. In the global bifurcations two homoclinic or two heteroclinic orbits collide and disappear. In the food chain model two attractors coexist; a stable limit cycle where the top-predator is absent and an interior attractor. In addition there is a saddle cycle. The stable manifold of this limit cycle forms the basin boundary of the interior attractor. We will show that this boundary has a complicated structure when there are heteroclinic orbits from a saddle equilibrium to this saddle limit cycle. A homoclinic bifurcation to a saddle limit cycle will be associated with a boundary crisis where the chaotic attractor disappears suddenly when a bifurcation parameter is varied. Thus, similar to a tangent local bifurcation for equilibria or limit cycles, this homoclinic global bifurcation marks a region in the parameter space where the top-predator goes extinct. The 'Paradox of Enrichment' says that increasing the concentration of nutrient input can cause destabilization of the otherwise stable interior equilibrium of a bi-trophic food chain. For a tri-trophic food chain enrichment of the environment can even lead to extinction of the highest trophic level.

3D implicit modeling of the Sishen Mine: new resolution of the geometry and origin of Fe mineralization

NASA Astrophysics Data System (ADS)

Stoch, B.; Anthonissen, C. J.; McCall, M.-J.; Basson, I. J.; Deacon, J.; Cloete, E.; Botha, J.; Britz, J.; Strydom, M.; Nel, D.; Bester, M.

2017-12-01

The Sishen deposit is one of the largest iron ore concentrations in current production. Hematite mineralization occurs along a strike length of 14 km, with a width of 3.2 km and a maximum vertical extent of 400 m below the original surface. The 986-Mt reserve incorporates a suite of individual orebodies, beneath a locally preserved tectonized unconformity, with a wide range of geometries, depths, and orientations. Fully constrained, implicit 3D modeling of the entire mining volume (> 70 km3), was undertaken to the original, pre-mining topography. The model incorporates 5287 mapping points and > 21,000 drillholes and provides exceptional insight into the original configuration of ore and its relationship to contacts, unconformities, and structures in the enclosing country rock. The bulk of ore occurs to the west of a strike-extensive, partially inverted normal fault (Sloep Fault), within an asymmetrical synclinal structure on its western flank. This linear, N-S distribution of deep, thick ore is punctuated by palaeosinkholes, wherein base-of-ore dips of greater than 45°, are concentrically arranged. Localized ore volumes also occur along faults and in fault-bounded, downthrown blocks, to the north of NW-SE- and NE-SW-trending strike-slip faults that show relatively minor uplift to the south, probably due to the Lomanian Namaqua-Natal Orogeny. The revised model demonstrates the proximity of ore to a tectonized unconformity and highlights the structural control on ore volumes, implying that Fe mineralization at Sishen cannot be exclusively attributed to supergene enrichment and concentric palaeosinkhole formation.

Crustal seismic structure beneath the southwest Yunnan region from joint inversion of body-wave and surface wave data

NASA Astrophysics Data System (ADS)

Luo, Y.; Thurber, C. H.; Zeng, X.; Zhang, L.

2016-12-01

Data from 71 broadband stations of a dense transportable array deployed in southwest Yunnan makes it possible to improve the resolution of the seismic model in this region. Continuous waveforms from 12 permanent stations of the China National Seismic Network were also used in this study. We utilized one-year continuous vertical component records to compute ambient noise cross-correlation functions (NCF). More than 3,000 NCFs were obtained and used to measure group velocities between 5 and 25 seconds with the frequency-time analysis method. This frequency band is most sensitive to crustal seismic structure, especially the upper and middle crust. The group velocity at short-period shows a clear azimuthal anisotropy with a north-south fast direction. The fast direction is consistent with previous seismic results revealed from shear wave splitting. More than 2,000 group velocity measurements were employed to invert the surface wave dispersion data for group velocity maps. We applied a finite difference forward modeling algorithm with an iterative inversion. A new body-wave and surface wave joint inversion algorithm (Fang et al., 2016) was utilized to improve the resolution of both P and S models. About 60,000 P wave and S wave arrivals from 1,780 local earthquakes, which occurred from May 2011 to December 2013 with magnitudes larger than 2.0, were manually picked. The new high-resolution seismic structure shows good consistency with local geological features, e.g. Tengchong Volcano. The earthquake locations also were refined with our new velocity model.

Crustal Structure in the Western Part of Romania from Local Seismic Tomography

NASA Astrophysics Data System (ADS)

Zaharia, Bogdan; Grecu, Bogdan; Popa, Mihaela; Oros, Eugen; Radulian, Mircea

2017-12-01

The inner part of the Carpathians in Romania belongs to the Carpathians-Pannonian system bordered by the Eastern Carpathians to the north and east, Southern Carpathians to the south and Pannonian Basin to the west. It is a complex tectonic region with differential folding mechanisms, post-collisional kinematics, rheology and thermal properties, including within its area the Apuseni Mountains and the Transylvanian Basin. The purpose of this study is to map the 3-D structure of the crust over this region on the basis of local earthquake data. Input data were recorded during the South Carpathian Project (2009-2011), a successful collaboration between the Institute of Geophysics and Tectonics of the University of Leeds and the National Institute for Earth Physics (NIEP), Romania. A temporary array of 32 broadband seismic stations (10 CMG-40T, 8 CMG-3T and 14 CMG-6TD) was installed across the western part of Romania (spaced at 40 to 50 km intervals) during the project. In addition, 25 stations deployed in the eastern Hungary and Serbia was considered. P- and S-wave arrivals are identified for all the selected events (minimum 7 phases per event with reasonable signal/noise ratio). All the events are first relocated using Joint Hypocentre Determination (JHD) technique. Then the well-located events were inverted to determine the crustal structure using LOTOS algorithm. The lateral variations of the crustal properties as resulted from the tomography image are interpreted in correlation with the station corrections estimated by JHD algorithm and with the post-collisional evolution of the Carpathians-Pannonian system.

Baselines and Degradation of Coral Reefs in the Northern Line Islands

PubMed Central

Sandin, Stuart A.; Smith, Jennifer E.; DeMartini, Edward E.; Dinsdale, Elizabeth A.; Donner, Simon D.; Friedlander, Alan M.; Konotchick, Talina; Malay, Machel; Maragos, James E.; Obura, David; Pantos, Olga; Paulay, Gustav; Richie, Morgan; Rohwer, Forest; Schroeder, Robert E.; Walsh, Sheila; Jackson, Jeremy B. C.; Knowlton, Nancy; Sala, Enric

2008-01-01

Effective conservation requires rigorous baselines of pristine conditions to assess the impacts of human activities and to evaluate the efficacy of management. Most coral reefs are moderately to severely degraded by local human activities such as fishing and pollution as well as global change, hence it is difficult to separate local from global effects. To this end, we surveyed coral reefs on uninhabited atolls in the northern Line Islands to provide a baseline of reef community structure, and on increasingly populated atolls to document changes associated with human activities. We found that top predators and reef-building organisms dominated unpopulated Kingman and Palmyra, while small planktivorous fishes and fleshy algae dominated the populated atolls of Tabuaeran and Kiritimati. Sharks and other top predators overwhelmed the fish assemblages on Kingman and Palmyra so that the biomass pyramid was inverted (top-heavy). In contrast, the biomass pyramid at Tabuaeran and Kiritimati exhibited the typical bottom-heavy pattern. Reefs without people exhibited less coral disease and greater coral recruitment relative to more inhabited reefs. Thus, protection from overfishing and pollution appears to increase the resilience of reef ecosystems to the effects of global warming. PMID:18301734

Effects of Long-term Diving Training on Cortical Gyrification.

PubMed

Zhang, Yuanchao; Zhao, Lu; Bi, Wenwei; Wang, Yue; Wei, Gaoxia; Evans, Alan; Jiang, Tianzi

2016-06-20

During human brain development, cortical gyrification, which is believed to facilitate compact wiring of neural circuits, has been shown to follow an inverted U-shaped curve, coinciding with the two-stage neurodevelopmental process of initial synaptic overproduction with subsequent pruning. This trajectory allows postnatal experiences to refine the wiring, which may manifest as endophenotypic changes in cortical gyrification. Diving experts, typical elite athletes who commence intensive motor training at a very young age in their early childhood, serve ideal models for examining the gyrification changes related to long-term intensive diving training. Using local gyrification index (LGI), we compared the cortical gyrification between 12 diving experts and 12 controls. Compared with controls, diving experts showed widespread LGI reductions in regions relevant to diving performance. Negative correlations between LGIs and years of diving training were also observed in diving experts. Further exploratory network efficiency analysis of structural cortical networks, inferred from interregional correlation of LGIs, revealed comparable global and local efficiency in diving experts relative to controls. These findings suggest that gyrification reductions in diving experts may be the result of long-term diving training which could refine the neural circuitry (via synaptic pruning) and might be the anatomical substrate underlying their extraordinary diving performance.

Mechanism of inverted-chirp infrasonic radiation from sprites

NASA Astrophysics Data System (ADS)

de Larquier, Sebastien; Pasko, Victor P.

2010-12-01

Farges and Blanc (2010) reported inverted-chirp infrasonic signals with high frequencies arriving before low frequencies, possibly emitted by sprite discharges and observed on the ground at close range (<100 km) from the source. In the present work a parallel version of a 2-D FDTD model of infrasound propagation in a realistic atmosphere is applied to demonstrate that the observed morphology of infrasound signals is consistent with general scaling of diameters of sprite streamers inversely proportionally to the air density. The smaller structures at lower altitudes radiate higher infrasonic frequencies that arrive first at the observational point on the ground, while the low frequency components are delayed because they originate at lower air densities at higher altitudes. The results demonstrate that strong absorption of high frequency infrasonic components at high altitudes (i.e., ˜0.2 dB/km for 8 Hz at 70 km) may also contribute to formation of inverted-chirp signals observed on the ground at close range.

Cool horizons lead to information loss

NASA Astrophysics Data System (ADS)

Chowdhury, Borun D.

2013-10-01

There are two evidences for information loss during black hole evaporation: (i) a pure state evolves to a mixed state and (ii) the map from the initial state to final state is non-invertible. Any proposed resolution of the information paradox must address both these issues. The firewall argument focuses only on the first and this leads to order one deviations from the Unruh vacuum for maximally entangled black holes. The nature of the argument does not extend to black holes in pure states. It was shown by Avery, Puhm and the author that requiring the initial state to final state map to be invertible mandates structure at the horizon even for pure states. The proof works if black holes can be formed in generic states and in this paper we show that this is indeed the case. We also demonstrate how models proposed by Susskind, Papadodimas et al. and Maldacena et al. end up making the initial to final state map non-invertible and thus make the horizon "cool" at the cost of unitarity.

Electronic structure of antifluorite Cu2X (X = S, Se, Te) within the modified Becke-Johnson potential plus an on-site Coulomb U.

PubMed

Zhang, Yubo; Wang, Youwei; Xi, Lili; Qiu, Ruihao; Shi, Xun; Zhang, Peihong; Zhang, Wenqing

2014-02-21

The traditional photon absorbers Cu2-xX (X = S, Se, and Te) have regained significant research attention in the search of earth-abundant photovoltaic materials. These moderate- and narrow-gap materials have also been shown to exhibit excellent thermoelectric properties recently. However, semimetallic band structures with inverted band orderings are predicted for antifluorite structure Cu2X using density functional theory with the local density approximation or the generalized gradient approximation. We find that semiconducting band structures and normal band orderings can be obtained using the modified Becke-Johnson potential plus an on-site Coulomb U (the mBJ+U approach), which is consistent with our earlier finding for diamond-like Cu-based multinary semiconductors [Y. Zhang, J. Zhang, W. Gao, T. A. Abtew, Y. Wang, P. Zhang, and W. Zhang, J. Chem. Phys. 139, 184706 (2013)]. The trend of the chemical bonding of Cu2X is analyzed, which shows that the positions of the valence band maximum and conduction band minimum are strongly affected by the inter-site pd and intra-site sp hybridizations, respectively. The calculated gaps of Cu2S and Cu2Se still seem to be underestimated compared with experimental results. We also discuss the effects of different structural phases and Cu disordering and deficiency on the bandgaps of these materials.

Far infrared edge photoresponse and persistent edge transport in an inverted InAs/GaSb heterostructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dyer, G. C.; Olson, B. V.; Hawkins, S. D.

2016-01-04

Direct current (DC) transport and far infrared photoresponse were studied an InAs/GaSb double quantum well with an inverted band structure. The DC transport depends systematically upon the DC bias configuration and operating temperature. Surprisingly, it reveals robust edge conduction despite prevalent bulk transport in our device of macroscopic size. Under 180 GHz far infrared illumination at oblique incidence, we measured a strong photovoltaic response. We conclude that quantum spin Hall edge transport produces the observed transverse photovoltages. Overall, our experimental results support a hypothesis that the photoresponse arises from direct coupling of the incident radiation field to edge states.

The theory and implementation of a high quality pulse width modulated waveform synthesiser applicable to voltage FED inverters

NASA Astrophysics Data System (ADS)

Lower, Kim Nigel

1985-03-01

Modulation processes associated with the digital implementation of pulse width modulation (PWM) switching strategies were examined. A software package based on a portable turnkey structure is presented. Waveform synthesizer implementation techniques are reviewed. A three phase PWM waveform synthesizer for voltage fed inverters was realized. It is based on a constant carrier frequency of 18 kHz and a regular sample, single edge, asynchronous PWM switching scheme. With high carrier frequencies, it is possible to utilize simple switching strategies and as a consequence, many advantages are highlighted, emphasizing the importance to industrial and office markets.

Improved localization of cellular membrane receptors using combined fluorescence microscopy and simultaneous topography and recognition imaging

NASA Astrophysics Data System (ADS)

Duman, M.; Pfleger, M.; Zhu, R.; Rankl, C.; Chtcheglova, L. A.; Neundlinger, I.; Bozna, B. L.; Mayer, B.; Salio, M.; Shepherd, D.; Polzella, P.; Moertelmaier, M.; Kada, G.; Ebner, A.; Dieudonne, M.; Schütz, G. J.; Cerundolo, V.; Kienberger, F.; Hinterdorfer, P.

2010-03-01

The combination of fluorescence microscopy and atomic force microscopy has a great potential in single-molecule-detection applications, overcoming many of the limitations coming from each individual technique. Here we present a new platform of combined fluorescence and simultaneous topography and recognition imaging (TREC) for improved localization of cellular receptors. Green fluorescent protein (GFP) labeled human sodium-glucose cotransporter (hSGLT1) expressed Chinese Hamster Ovary (CHO) cells and endothelial cells (MyEnd) from mouse myocardium stained with phalloidin-rhodamine were used as cell systems to study AFM topography and fluorescence microscopy on the same surface area. Topographical AFM images revealed membrane features such as lamellipodia, cytoskeleton fibers, F-actin filaments and small globular structures with heights ranging from 20 to 30 nm. Combined fluorescence and TREC imaging was applied to detect density, distribution and localization of YFP-labeled CD1d molecules on α-galactosylceramide (αGalCer)-loaded THP1 cells. While the expression level, distribution and localization of CD1d molecules on THP1 cells were detected with fluorescence microscopy, the nanoscale distribution of binding sites was investigated with molecular recognition imaging by using a chemically modified AFM tip. Using TREC on the inverted light microscope, the recognition sites of cell receptors were detected in recognition images with domain sizes ranging from ~ 25 to ~ 160 nm, with the smaller domains corresponding to a single CD1d molecule.

Improved localization of cellular membrane receptors using combined fluorescence microscopy and simultaneous topography and recognition imaging.

PubMed

Duman, M; Pfleger, M; Zhu, R; Rankl, C; Chtcheglova, L A; Neundlinger, I; Bozna, B L; Mayer, B; Salio, M; Shepherd, D; Polzella, P; Moertelmaier, M; Kada, G; Ebner, A; Dieudonne, M; Schütz, G J; Cerundolo, V; Kienberger, F; Hinterdorfer, P

2010-03-19

The combination of fluorescence microscopy and atomic force microscopy has a great potential in single-molecule-detection applications, overcoming many of the limitations coming from each individual technique. Here we present a new platform of combined fluorescence and simultaneous topography and recognition imaging (TREC) for improved localization of cellular receptors. Green fluorescent protein (GFP) labeled human sodium-glucose cotransporter (hSGLT1) expressed Chinese Hamster Ovary (CHO) cells and endothelial cells (MyEnd) from mouse myocardium stained with phalloidin-rhodamine were used as cell systems to study AFM topography and fluorescence microscopy on the same surface area. Topographical AFM images revealed membrane features such as lamellipodia, cytoskeleton fibers, F-actin filaments and small globular structures with heights ranging from 20 to 30 nm. Combined fluorescence and TREC imaging was applied to detect density, distribution and localization of YFP-labeled CD1d molecules on alpha-galactosylceramide (alphaGalCer)-loaded THP1 cells. While the expression level, distribution and localization of CD1d molecules on THP1 cells were detected with fluorescence microscopy, the nanoscale distribution of binding sites was investigated with molecular recognition imaging by using a chemically modified AFM tip. Using TREC on the inverted light microscope, the recognition sites of cell receptors were detected in recognition images with domain sizes ranging from approximately 25 to approximately 160 nm, with the smaller domains corresponding to a single CD1d molecule.

An evaluation of teaching methods in the introductory physics classroom

NASA Astrophysics Data System (ADS)

Savage, Lauren Michelle Williams

The introductory physics mechanics course at the University of North Carolina at Charlotte has a history of relatively high DFW rates. In 2011, the course was redesigned from the traditional lecture format to the inverted classroom format (flipped). This format inverts the classroom by introducing material in a video assigned as homework while the instructor conducts problem solving activities and guides discussions during the regular meetings. This format focuses on student-centered learning and is more interactive and engaging. To evaluate the effectiveness of the new method, final exam data over the past 10 years was mined and the pass rates examined. A normalization condition was developed to evaluate semesters equally. The two teaching methods were compared using a grade distribution across multiple semesters. Students in the inverted class outperformed those in the traditional class: "A"s increased by 22% and "B"s increased by 38%. The final exam pass rate increased by 12% under the inverted classroom approach. The same analysis was used to compare the written and online final exam formats. Surprisingly, no students scored "A"s on the online final. However, the percent of "B"s increased by 136%. Combining documented best practices from a literature review with personal observations of student performance and attitudes from first hand classroom experience as a teaching assistant in both teaching methods, reasons are given to support the continued use of the inverted classroom approach as well as the online final. Finally, specific recommendations are given to improve the course structure where weaknesses have been identified.

Fabrication of flexible indium tin oxide-free polymer solar cells with silver nanowire transparent electrode

NASA Astrophysics Data System (ADS)

Lin, Ming-Yi; Chen, Tsun-Jui; Xu, Wei-Feng; Hsiao, Li-Jen; Budiawan, Widhya; Tu, Wei-Chen; Chen, Shih-Lun; Chu, Chih-Wei; Wei, Pei-Kuen

2018-03-01

Flexible indium tin oxide (ITO)-free poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PC61BM) solar cells with a spin-coated silver nanowire transparent electrode are demonstrated. The solution-processed silver nanowire thin film not only exhibits high transmission (∼87%), but also shows low sheet resistance R s (∼25 Ω/sq). For solar cells with a conventional structure, the power conversion efficiency (PCE) of devices based on silver nanowires can reach around 2.29%. For the inverted structure, the PCE of devices can reach 3.39%. Conventional and inverted flexible ITO-based P3HT:PC61BM solar cells are also fabricated as a reference for comparison. For both types of solar cells, the PCE of ITO-free devices is very close that of an ITO-based polymer solar cell.

Effect of hydrostatic pressure and uniaxial strain on the electronic structure of Pb 1-xSn xTe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geilhufe, Matthias; Nayak, Sanjeev K.; Thomas, Stefan

2015-12-09

The electronic structure of Pb 1–xSn xTe is studied by using the relativistic Korringa-Kohn-Rostoker Green function method in the framework of density functional theory. For all concentrations x, Pb 1–xSn xTe is a direct semiconductor with a narrow band gap. In contrast to pure lead telluride, tin telluride shows an inverted band characteristic close to the Fermi energy. It will be shown that this particular property can be tuned, first, by alloying PbTe and SnTe and, second, by applying hydrostatic pressure or uniaxial strain. Furthermore, the magnitude of strain needed to switch between the regular and inverted band gap canmore » be tuned by the alloy composition. In conclusion, there is a range of potential usage of Pb 1–xSn xTe for spintronic applications.« less

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events

PubMed Central

Suzuki, Yuki; Sakai, Nobuaki; Yoshida, Aiko; Uekusa, Yoshitsugu; Yagi, Akira; Imaoka, Yuka; Ito, Shuichi; Karaki, Koichi; Takeyasu, Kunio

2013-01-01

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events. PMID:23823461

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events.

PubMed

Suzuki, Yuki; Sakai, Nobuaki; Yoshida, Aiko; Uekusa, Yoshitsugu; Yagi, Akira; Imaoka, Yuka; Ito, Shuichi; Karaki, Koichi; Takeyasu, Kunio

2013-01-01

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events.

Application of differential interference contrast with inverted microscopes to the in vitro perfused nephron.

PubMed

Horster, M; Gundlach, H

1979-12-01

The study of in vitro perfused individual nephron segments requires a microscope which provides: (1) easy access to the specimen for measurement of cellular solute flux and voltage; (2) an image with high resolution and contrast; (3) optical sectioning of the object at different levels; and (4) rapid recording of the morphological phenomena. This paper describes an example of commercially available apparatus meeting the above requirements, and illustrates its efficiency. The microscope is of the inverted type (Zeiss IM 35) equipped with differential-interference-contrast (DIC) with a long working distance, and an automatically controlled camera system. The microscopic image exhibits cellular and intercellular details in the unstained transporting mammalian nephron segments despite their tubular structure and great thickness and makes obvious function-structure correlations (e.g. cell volume changes); luminal and contraluminal cell borders are well resolved for controlled microelectrode impalement.

Inverted-V events simultaneously observed with the Freja satellite and from the ground

NASA Astrophysics Data System (ADS)

Haerendel, G.; Frey, H. U.; Bauer, O. H.; Rieger, E.; Clemmons, J.; Boehm, M. H.; Wallis, D. D.; Lühr, H.

The paper reports data received from the Freja satellite during two passes over broad auroral arc systems or inverted-V events above Gillam/Manitoba when special wide-angle CCD cameras were operated at this location in addition to the CANOPUS network. Detailed comparisons of the visible structures with modulations of the primary electron fluxes are performed. Motions of this fine structures are interpreted in terms of high-altitude electric fields shielded from the lower ionosphere. Simultaneous readings of current density, accelerating voltage and energy flux, the latter determined both from particle and auroral brightness measurements, are found to be internally consistent. We calculate from these data the effective resistance encountered by the electric currents and find agreement with the kinetic theory of the mirror impedance, if we allow for substantial variations in density and energy of the source electrons in the magnetosphere.

Physical Nature of the Processes in Structure Forming, Phase and Chemical Composition of pipe Permanent Joints when MMA Welding

NASA Astrophysics Data System (ADS)

Il'yaschenko, D. P.; Chinakhov, D. A.; Danilov, V. I.; Sadykov, I. D.

2016-04-01

The paper outlines peculiarities of structure formation, phase and chemical composition in regard to heat content in molten electrode metal beads when pipe steel (steel 09G2S) welding using power sources with various energy characteristics. Mathematical calculations indicate an inverter power source provides minor heat content into the bead of electrode metal when welding. Experimental research has pointed at 4-9 % increase in impact strength of joints produced using an inverter power source in comparison with samples produced applying a diode rectifier. The following factors can possibly give rise to the increasing impact strength: difference in microstructures of weld joints, up to 50% shortening ferritic plates in metal of weld joint, change in dimensions of ferritic grains in the heat-affected zone by as much as 17.5 %, and decrease in the extent of heat-affected zone by 50%.

Comparing the performance of two CBIRS indexing schemes

NASA Astrophysics Data System (ADS)

Mueller, Wolfgang; Robbert, Guenter; Henrich, Andreas

2003-01-01

Content based image retrieval (CBIR) as it is known today has to deal with a number of challenges. Quickly summarized, the main challenges are firstly, to bridge the semantic gap between high-level concepts and low-level features using feedback, secondly to provide performance under adverse conditions. High-dimensional spaces, as well as a demanding machine learning task make the right way of indexing an important issue. When indexing multimedia data, most groups opt for extraction of high-dimensional feature vectors from the data, followed by dimensionality reduction like PCA (Principal Components Analysis) or LSI (Latent Semantic Indexing). The resulting vectors are indexed using spatial indexing structures such as kd-trees or R-trees, for example. Other projects, such as MARS and Viper propose the adaptation of text indexing techniques, notably the inverted file. Here, the Viper system is the most direct adaptation of text retrieval techniques to quantized vectors. However, while the Viper query engine provides decent performance together with impressive user-feedback behavior, as well as the possibility for easy integration of long-term learning algorithms, and support for potentially infinite feature vectors, there has been no comparison of vector-based methods and inverted-file-based methods under similar conditions. In this publication, we compare a CBIR query engine that uses inverted files (Bothrops, a rewrite of the Viper query engine based on a relational database), and a CBIR query engine based on LSD (Local Split Decision) trees for spatial indexing using the same feature sets. The Benchathlon initiative works on providing a set of images and ground truth for simulating image queries by example and corresponding user feedback. When performing the Benchathlon benchmark on a CBIR system (the System Under Test, SUT), a benchmarking harness connects over internet to the SUT, performing a number of queries using an agreed-upon protocol, the multimedia retrieval markup language (MRML). Using this benchmark one can measure the quality of retrieval, as well as the overall (speed) performance of the benchmarked system. Our Benchmarks will draw on the Benchathlon"s work for documenting the retrieval performance of both inverted file-based and LSD tree based techniques. However in addition to these results, we will present statistics, that can be obtained only inside the system under test. These statistics will include the number of complex mathematical operations, as well as the amount of data that has to be read from disk during operation of a query.

Gas tube-switched high voltage DC power converter

DOEpatents

She, Xu; Bray, James William; Sommerer, Timothy John; Chokhawala, Rahul

2018-05-15

A direct current (DC)-DC converter includes a transformer and a gas tube-switched inverter circuit. The transformer includes a primary winding and a secondary winding. The gas tube-switched inverter circuit includes first and second inverter load terminals and first and second inverter input terminals. The first and second inverter load terminals are coupled to the primary winding. The first and second inverter input terminals are couplable to a DC node. The gas tube-switched inverter circuit further includes a plurality of gas tube switches respectively coupled between the first and second inverter load terminals and the first and second inverter input terminals. The plurality of gas tube switches is configured to operate to generate an alternating current (AC) voltage at the primary winding.

The inverted free energy landscape of an intrinsically disordered peptide by simulations and experiments.

PubMed

Granata, Daniele; Baftizadeh, Fahimeh; Habchi, Johnny; Galvagnion, Celine; De Simone, Alfonso; Camilloni, Carlo; Laio, Alessandro; Vendruscolo, Michele

2015-10-26

The free energy landscape theory has been very successful in rationalizing the folding behaviour of globular proteins, as this representation provides intuitive information on the number of states involved in the folding process, their populations and pathways of interconversion. We extend here this formalism to the case of the Aβ40 peptide, a 40-residue intrinsically disordered protein fragment associated with Alzheimer's disease. By using an advanced sampling technique that enables free energy calculations to reach convergence also in the case of highly disordered states of proteins, we provide a precise structural characterization of the free energy landscape of this peptide. We find that such landscape has inverted features with respect to those typical of folded proteins. While the global free energy minimum consists of highly disordered structures, higher free energy regions correspond to a large variety of transiently structured conformations with secondary structure elements arranged in several different manners, and are not separated from each other by sizeable free energy barriers. From this peculiar structure of the free energy landscape we predict that this peptide should become more structured and not only more compact, with increasing temperatures, and we show that this is the case through a series of biophysical measurements.

The inverted free energy landscape of an intrinsically disordered peptide by simulations and experiments

PubMed Central

Granata, Daniele; Baftizadeh, Fahimeh; Habchi, Johnny; Galvagnion, Celine; De Simone, Alfonso; Camilloni, Carlo; Laio, Alessandro; Vendruscolo, Michele

2015-01-01

The free energy landscape theory has been very successful in rationalizing the folding behaviour of globular proteins, as this representation provides intuitive information on the number of states involved in the folding process, their populations and pathways of interconversion. We extend here this formalism to the case of the Aβ40 peptide, a 40-residue intrinsically disordered protein fragment associated with Alzheimer’s disease. By using an advanced sampling technique that enables free energy calculations to reach convergence also in the case of highly disordered states of proteins, we provide a precise structural characterization of the free energy landscape of this peptide. We find that such landscape has inverted features with respect to those typical of folded proteins. While the global free energy minimum consists of highly disordered structures, higher free energy regions correspond to a large variety of transiently structured conformations with secondary structure elements arranged in several different manners, and are not separated from each other by sizeable free energy barriers. From this peculiar structure of the free energy landscape we predict that this peptide should become more structured and not only more compact, with increasing temperatures, and we show that this is the case through a series of biophysical measurements. PMID:26498066

An efficient sequential strategy for realizing cross-gradient joint inversion: method and its application to 2-D cross borehole seismic traveltime and DC resistivity tomography

NASA Astrophysics Data System (ADS)

Gao, Ji; Zhang, Haijiang

2018-05-01

Cross-gradient joint inversion that enforces structural similarity between different models has been widely utilized in jointly inverting different geophysical data types. However, it is a challenge to combine different geophysical inversion systems with the cross-gradient structural constraint into one joint inversion system because they may differ greatly in the model representation, forward modelling and inversion algorithm. Here we propose a new joint inversion strategy that can avoid this issue. Different models are separately inverted using the existing inversion packages and model structure similarity is only enforced through cross-gradient minimization between two models after each iteration. Although the data fitting and structural similarity enforcing processes are decoupled, our proposed strategy is still able to choose appropriate models to balance the trade-off between geophysical data fitting and structural similarity. This is realized by using model perturbations from separate data inversions to constrain the cross-gradient minimization process. We have tested this new strategy on 2-D cross borehole synthetic seismic traveltime and DC resistivity data sets. Compared to separate geophysical inversions, our proposed joint inversion strategy fits the separate data sets at comparable levels while at the same time resulting in a higher structural similarity between the velocity and resistivity models.

[Inverted meiosis and its place in the evolution of sexual reproduction pathways].

PubMed

Bogdanov, Yu F

2016-05-01

Inverted meiosis is observed in plants (Cyperaceae and Juncaceae) and insects (Coccoidea, Aphididae) with holocentric chromosomes, the centromeres of which occupy from 70 to 90% of the metaphase chromosome length. In the first meiotic division (meiosis I), chiasmata are formed and rodlike bivalents orient equationally, and in anaphase I, sister chromatids segregate to the poles; the diploid chromosome number is maintained. Non-sister chromatids of homologous chromosomes remain in contact during interkinesis and prophase II and segregate in anaphase II, forming haploid chromosome sets. The segregation of sister chromatids in meiosis I was demonstrated by example of three plant species that were heterozygous for chromosomal rearrangements. In these species, sister chromatids, marked with rearrangement, segregated in anaphase I. Using fluorescent antibodies, it was demonstrated that meiotic recombination enzymes Spo11 and Rad5l, typical of canonical meiosis, functioned at the meiotic prophase I of pollen mother cells of Luzula elegance and Rhynchospora pubera. Moreover, antibodies to synaptonemal complexes proteins ASY1 and ZYP1 were visualized as filamentous structures, pointing to probable formation of synaptonemal complexes. In L. elegance, chiasmata are formed by means of chromatin threads containing satellite DNA. According to the hypothesis of the author of this review, equational division of sister chromatids at meiosis I in the organisms with inverted meiosis can be explained by the absence of specific meiotic proteins (shugoshins). These proteins are able to protect cohesins of holocentric centromeres from hydrolysis by separases at meiosis I, as occurs in the organisms with monocentric chromosomes and canonical meiosis. The basic type of inverted meiosis was described in Coccoidea and Aphididae males. In their females, the variants of parthenogenesis were also observed. Until now, the methods of molecular cytogenetics were not applied for the analysis of inverted meiosis in Coccoidea and Aphididae. Evolutionary, inverted meiosis is thought to have appeared secondarily as an adaptation of the molecular mechanisms of canonical meiosis to chromosome holocentrism.

Ultraviolet Electrically Injected Light Sources With Epitaxial ZnO-Based Heterojunctions

DTIC Science & Technology

2007-08-01

ohmic contacts to ZnO , UV photoconductors, and thin film transistors . The integration of ferroelectric oxide thin films with ZnO was also investigated... transistors . The integration of ferroelectric oxide thin films with ZnO was also investigated, as a potential means of locally inverting ZnO to p-type, and to...low contact resistivity ......................... 8 ZnO Thin Film Transistors

On the Path to SunShot. Emerging Issues and Challenges in Integrating Solar with the Distribution System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmintier, Bryan; Broderick, Robert; Mather, Barry

2016-05-01

This report analyzes distribution-integration challenges, solutions, and research needs in the context of distributed generation from PV (DGPV) deployment to date and the much higher levels of deployment expected with achievement of the U.S. Department of Energy's SunShot targets. Recent analyses have improved estimates of the DGPV hosting capacities of distribution systems. This report uses these results to statistically estimate the minimum DGPV hosting capacity for the contiguous United States using traditional inverters of approximately 170 GW without distribution system modifications. This hosting capacity roughly doubles if advanced inverters are used to manage local voltage and additional minor, low-cost changesmore » could further increase these levels substantially. Key to achieving these deployment levels at minimum cost is siting DGPV based on local hosting capacities, suggesting opportunities for regulatory, incentive, and interconnection innovation. Already, pre-computed hosting capacity is beginning to expedite DGPV interconnection requests and installations in select regions; however, realizing SunShot-scale deployment will require further improvements to DGPV interconnection processes, standards and codes, and compensation mechanisms so they embrace the contributions of DGPV to system-wide operations. SunShot-scale DGPV deployment will also require unprecedented coordination of the distribution and transmission systems. This includes harnessing DGPV's ability to relieve congestion and reduce system losses by generating closer to loads; minimizing system operating costs and reserve deployments through improved DGPV visibility; developing communication and control architectures that incorporate DGPV into system operations; providing frequency response, transient stability, and synthesized inertia with DGPV in the event of large-scale system disturbances; and potentially managing reactive power requirements due to large-scale deployment of advanced inverter functions. Finally, additional local and system-level value could be provided by integrating DGPV with energy storage and 'virtual storage,' which exploits improved management of electric vehicle charging, building energy systems, and other large loads. Together, continued innovation across this rich distribution landscape can enable the very-high deployment levels envisioned by SunShot.« less

Passive electrical monitoring and localization of fluid leakages from wells

NASA Astrophysics Data System (ADS)

Revil, A.; Mao, D.; Haas, A. K.; Karaoulis, M.; Frash, L.

2015-02-01

Electrokinetic phenomena are a class of cross-coupling phenomena involving the relative displacement between the pore water (together with the electrical diffuse layer) with respect to the solid phase of a porous material. We demonstrate that electrical fields of electrokinetic nature can be associated with fluid leakages from wells. These leakages can be remotely monitored and the resulting signals used to localize their causative source distribution both in the laboratory and in field conditions. The first laboratory experiment (Experiment #1) shows how these electrical fields can be recorded at the surface of a cement block during the leakage of a brine from a well. The measurements were performed with a research-grade medical electroencephalograph and were inverted using a genetic algorithm to localize the causative source of electrical current and therefore, localize the leak in the block. Two snapshots of electrical signals were used to show how the leak evolved over time. The second experiment (Experiment #2) was performed to see if we could localize a pulse water injection from a shallow well in field conditions in the case of a heterogeneous subsurface. We used the same equipment as in Experiment #1 and processed the data with a trend removal algorithm, picking the amplitude from 24 receiver channels just after the water injection. The amplitude of the electric signals changed from the background level indicating that a volume of water was indeed flowing inside the well into the surrounding soil and then along the well. We used a least-square inversion algorithm to invert a snapshot of the electrical potential data at the injection time to localize the source of the self-potential signals. The inversion results show positive potential anomalies in the vicinity of the well. For both experiments, forward numerical simulations of the problem using a finite element package were performed in order to assess the underlying physics of the causative source of the observed electrical potential anomalies and how they are related to the flow of the water phase.

An islanding detection methodology combining decision trees and Sandia frequency shift for inverter-based distributed generations

DOE PAGES

Azim, Riyasat; Li, Fangxing; Xue, Yaosuo; ...

2017-07-14

Distributed generations (DGs) for grid-connected applications require an accurate and reliable islanding detection methodology (IDM) for secure system operation. This paper presents an IDM for grid-connected inverter-based DGs. The proposed method is a combination of passive and active islanding detection techniques for aggregation of their advantages and elimination/minimisation of the drawbacks. In the proposed IDM, the passive method utilises critical system attributes extracted from local voltage measurements at target DG locations as well as employs decision tree-based classifiers for characterisation and detection of islanding events. The active method is based on Sandia frequency shift technique and is initiated only whenmore » the passive method is unable to differentiate islanding events from other system events. Thus, the power quality degradation introduced into the system by active islanding detection techniques can be minimised. Furthermore, a combination of active and passive techniques allows detection of islanding events under low power mismatch scenarios eliminating the disadvantage associated with the use of passive techniques alone. Finally, detailed case study results demonstrate the effectiveness of the proposed method in detection of islanding events under various power mismatch scenarios, load quality factors and in the presence of single or multiple grid-connected inverter-based DG units.« less

An islanding detection methodology combining decision trees and Sandia frequency shift for inverter-based distributed generations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azim, Riyasat; Li, Fangxing; Xue, Yaosuo

Distributed generations (DGs) for grid-connected applications require an accurate and reliable islanding detection methodology (IDM) for secure system operation. This paper presents an IDM for grid-connected inverter-based DGs. The proposed method is a combination of passive and active islanding detection techniques for aggregation of their advantages and elimination/minimisation of the drawbacks. In the proposed IDM, the passive method utilises critical system attributes extracted from local voltage measurements at target DG locations as well as employs decision tree-based classifiers for characterisation and detection of islanding events. The active method is based on Sandia frequency shift technique and is initiated only whenmore » the passive method is unable to differentiate islanding events from other system events. Thus, the power quality degradation introduced into the system by active islanding detection techniques can be minimised. Furthermore, a combination of active and passive techniques allows detection of islanding events under low power mismatch scenarios eliminating the disadvantage associated with the use of passive techniques alone. Finally, detailed case study results demonstrate the effectiveness of the proposed method in detection of islanding events under various power mismatch scenarios, load quality factors and in the presence of single or multiple grid-connected inverter-based DG units.« less

Development of a hardware-based AC microgrid for AC stability assessment

NASA Astrophysics Data System (ADS)

Swanson, Robert R.

As more power electronic-based devices enable the development of high-bandwidth AC microgrids, the topic of microgrid power distribution stability has become of increased interest. Recently, researchers have proposed a relatively straightforward method to assess the stability of AC systems based upon the time-constants of sources, the net bus capacitance, and the rate limits of sources. In this research, a focus has been to develop a hardware test system to evaluate AC system stability. As a first step, a time domain model of a two converter microgrid was established in which a three phase inverter acts as a power source and an active rectifier serves as an adjustable constant power AC load. The constant power load can be utilized to create rapid power flow transients to the generating system. As a second step, the inverter and active rectifier were designed using a Smart Power Module IGBT for switching and an embedded microcontroller as a processor for algorithm implementation. The inverter and active rectifier were designed to operate simultaneously using a synchronization signal to ensure each respective local controller operates in a common reference frame. Finally, the physical system was created and initial testing performed to validate the hardware functionality as a variable amplitude and variable frequency AC system.

Expression analysis for inverted effects of serotonin transporter inactivation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ichikawa, Manabu; Okamura-Oho, Yuko; Shimokawa, Kazuro

2008-03-28

Inactivation of serotonin transporter (HTT) by pharmacologically in the neonate or genetically increases risk for depression in adulthood, whereas pharmacological inhibition of HTT ameliorates symptoms in depressed patients. The differing role of HTT function during early development and in adult brain plasticity in causing or reversing depression remains an unexplained paradox. To address this we profiled the gene expression of adult Htt knockout (Htt KO) mice and HTT inhibitor-treated mice. Inverted profile changes between the two experimental conditions were seen in 30 genes. Consistent results of the upstream regulatory element search and the co-localization search of these genes indicated thatmore » the regulation may be executed by Pax5, Pax7 and Gata3, known to be involved in the survival, proliferation, and migration of serotonergic neurons in the developing brain, and these factors are supposed to keep functioning to regulate downstream genes related to serotonin system in the adult brain.« less

Evaluation of Inversion Methods Applied to Ionospheric ro Observations

NASA Astrophysics Data System (ADS)

Rios Caceres, Arq. Estela Alejandra; Rios, Victor Hugo; Guyot, Elia

The new technique of radio-occultation can be used to study the Earth's ionosphere. The retrieval processes of ionospheric profiling from radio occultation observations usually assume spherical symmetry of electron density distribution at the locality of occultation and use the Abel integral transform to invert the measured total electron content (TEC) values. This pa-per presents a set of ionospheric profiles obtained from SAC-C satellite with the Abel inversion technique. The effects of the ionosphere on the GPS signal during occultation, such as bending and scintillation, are examined. Electron density profiles are obtained using the Abel inversion technique. Ionospheric radio occultations are validated using vertical profiles of electron con-centration from inverted ionograms , obtained from ionosonde sounding in the vicinity of the occultation. Results indicate that the Abel transform works well in the mid-latitudes during the daytime, but is less accurate during the night-time.

Inverting dynamic force microscopy: From signals to time-resolved interaction forces

PubMed Central

Stark, Martin; Stark, Robert W.; Heckl, Wolfgang M.; Guckenberger, Reinhard

2002-01-01

Transient forces between nanoscale objects on surfaces govern friction, viscous flow, and plastic deformation, occur during manipulation of matter, or mediate the local wetting behavior of thin films. To resolve transient forces on the (sub) microsecond time and nanometer length scale, dynamic atomic force microscopy (AFM) offers largely unexploited potential. Full spectral analysis of the AFM signal completes dynamic AFM. Inverting the signal formation process, we measure the time course of the force effective at the sensing tip. This approach yields rich insight into processes at the tip and dispenses with a priori assumptions about the interaction, as it relies solely on measured data. Force measurements on silicon under ambient conditions demonstrate the distinct signature of the interaction and reveal that peak forces exceeding 200 nN are applied to the sample in a typical imaging situation. These forces are 2 orders of magnitude higher than those in covalent bonds. PMID:12070341

Cortical topography of intracortical inhibition influences the speed of decision making.

PubMed

Wilimzig, Claudia; Ragert, Patrick; Dinse, Hubert R

2012-02-21

The neocortex contains orderly topographic maps; however, their functional role remains controversial. Theoretical studies have suggested a role in minimizing computational costs, whereas empirical studies have focused on spatial localization. Using a tactile multiple-choice reaction time (RT) task before and after the induction of perceptual learning through repetitive sensory stimulation, we extend the framework of cortical topographies by demonstrating that the topographic arrangement of intracortical inhibition contributes to the speed of human perceptual decision-making processes. RTs differ among fingers, displaying an inverted U-shaped function. Simulations using neural fields show the inverted U-shaped RT distribution as an emergent consequence of lateral inhibition. Weakening inhibition through learning shortens RTs, which is modeled through topographically reorganized inhibition. Whereas changes in decision making are often regarded as an outcome of higher cortical areas, our data show that the spatial layout of interaction processes within representational maps contributes to selection and decision-making processes.

Cortical topography of intracortical inhibition influences the speed of decision making

PubMed Central

Wilimzig, Claudia; Ragert, Patrick; Dinse, Hubert R.

2012-01-01

The neocortex contains orderly topographic maps; however, their functional role remains controversial. Theoretical studies have suggested a role in minimizing computational costs, whereas empirical studies have focused on spatial localization. Using a tactile multiple-choice reaction time (RT) task before and after the induction of perceptual learning through repetitive sensory stimulation, we extend the framework of cortical topographies by demonstrating that the topographic arrangement of intracortical inhibition contributes to the speed of human perceptual decision-making processes. RTs differ among fingers, displaying an inverted U-shaped function. Simulations using neural fields show the inverted U-shaped RT distribution as an emergent consequence of lateral inhibition. Weakening inhibition through learning shortens RTs, which is modeled through topographically reorganized inhibition. Whereas changes in decision making are often regarded as an outcome of higher cortical areas, our data show that the spatial layout of interaction processes within representational maps contributes to selection and decision-making processes. PMID:22315409

Culvert rehabilitation & invert lining using fiber reinforced polymer (FRP) composites.

DOT National Transportation Integrated Search

2010-06-01

As part of the state of Maine bridge funding initiative, MaineDOT has partnered with the University of : Maines AEWC Advanced Structures and Composite Center and the Maine composites industry to : incorporate composite technologies into bridge con...

3D isotropic shear wave velocity structure of the lithosphere-asthenosphere system underneath the Alpine-Mediterranean Mobile belt

NASA Astrophysics Data System (ADS)

El-Sharkawy, Amr; Weidle, Christian; Christiano, Luigia; Lebedev, Sergei; Meier, Thomas

2017-04-01

The Alpine-Mediterranean mobile belt is, tectonically, one of the most complicated and active regions in the world. Since the Mesozoic, collisions between Gondwana-derived continental blocks and Eurasia, due to the closure of a number of rather small ocean basins, have shaped the Mediterranean geology. During the late Mesozoic, it was dominated by subduction zones (e.g., in Anatolia, the Dinarides, the Carpathians, the Alps, the Apennines, and the Betics), which inverted the extensional regime, consuming the previously formed oceanic lithosphere, the adjacent passive continental margins and presumably partly also continental lithosphere. The location, distribution, and evolution of these subduction zones were mainly controlled by the continental or oceanic nature, density, and thickness of the lithosphere inherited from the Mesozoic rift after the European Variscan Orogeny. Despite the numerous studies that have attempted to characterize the lithosphere-asthenosphere structure in that area, details of the lithospheric structure and dynamics, as well as flow in the asthenosphere are, however, poorly known. A 3D shear-wave velocity structure of the lithosphere-asthenosphere system in the Mediterranean is investigated using new tomographic images obtained from surface wave tomography. An automated algorithm for inter-station phase velocity measurements is applied here to obtain both Rayleigh and Love fundamental mode phase velocities. We utilize a database consisting of more than 4000 seismic events recorded by more than 2000 broadband seismic stations within the area, provided by the European Integrated Data Archive (WebDc/EIDA) and IRIS. Moreover, for the first time, data from the Egyptian National Seismological Network (ENSN), recorded by up to 25 broad band seismic stations, are also included in the analysis. For each station pair, approximately located on the same great circle path, the recorded waveforms are cross correlated and the dispersion curves of fundamental modes are calculated from the phase of the cross correlation functions weighted in the time-frequency plane. Path average dispersion curves are obtained by averaging the smooth parts of single-event dispersion curves. A careful quality control of the resulting phase velocities is performed. We calculate maps of Love and Rayleigh phase velocity at more than 100 different periods. The phase-velocity maps provide the local phase-velocity dispersion curve for each geographical grid node of the map. Each of these local dispersion curves is inverted individually for 1D shear wave velocity model using a newly implemented Particle Swarm Optimization (PSO) algorithm. The resulted 1D velocity models are then combined to construct the 3D shear-velocity model. Horizontal and vertical cross sections through the 3D isotropic model reveal significant variations in shear wave velocity with depth, and lateral changes in the crust and upper mantle structure emphasizing the processes associated with the convergence of the Eurasian and African plates. Key words: seismic tomography, Mediterranean, surface waves, particle swarm optimization.

Reliability-Based Design Optimization of a Composite Airframe Component

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Pai, Shantaram S.; Coroneos, Rula M.

2009-01-01

A stochastic design optimization methodology (SDO) has been developed to design components of an airframe structure that can be made of metallic and composite materials. The design is obtained as a function of the risk level, or reliability, p. The design method treats uncertainties in load, strength, and material properties as distribution functions, which are defined with mean values and standard deviations. A design constraint or a failure mode is specified as a function of reliability p. Solution to stochastic optimization yields the weight of a structure as a function of reliability p. Optimum weight versus reliability p traced out an inverted-S-shaped graph. The center of the inverted-S graph corresponded to 50 percent (p = 0.5) probability of success. A heavy design with weight approaching infinity could be produced for a near-zero rate of failure that corresponds to unity for reliability p (or p = 1). Weight can be reduced to a small value for the most failure-prone design with a reliability that approaches zero (p = 0). Reliability can be changed for different components of an airframe structure. For example, the landing gear can be designed for a very high reliability, whereas it can be reduced to a small extent for a raked wingtip. The SDO capability is obtained by combining three codes: (1) The MSC/Nastran code was the deterministic analysis tool, (2) The fast probabilistic integrator, or the FPI module of the NESSUS software, was the probabilistic calculator, and (3) NASA Glenn Research Center s optimization testbed CometBoards became the optimizer. The SDO capability requires a finite element structural model, a material model, a load model, and a design model. The stochastic optimization concept is illustrated considering an academic example and a real-life raked wingtip structure of the Boeing 767-400 extended range airliner made of metallic and composite materials.

A combined magnetometry and gravity study across Zagros orogeny in Iran

NASA Astrophysics Data System (ADS)

Abedi, Maysam; Oskooi, Behrooz

2015-11-01

In this work, the structural geology and the tectonic conditions of the Zagros orogeny along the route of Qom to Kermanshah cities were investigated using the combined geophysical methods of the airborne magnetometry and the ground-based gravity data. Airborne magnetometry data of Iran with a line space of survey, 7.5 km, were used to model the magnetic susceptibility property along the route. At first, the airborne magnetic data were stably 500-m downward continued to the ground surface in order to enhance minor changes of the Earth's magnetic field over the studied region. Afterward, 3D inverse modeling of the magnetic data was implemented to the downward continued data, and subsequently the section of magnetic susceptibility variation along the desired route was extracted and imaged at depth. The acquired model could appropriately predict the observed magnetic data, showing low misfit values between the observation and the predicted data. The analytic signal filter was applied to the reduced-to-pole (RTP) magnetic data leading to the determination of the active and probable hidden faults in the structural zones of the Zagros, such as Sanandaj-Sirjan, Central Domain (CD) and Urumieh-Dokhtar based upon the generated peaks along the profile of analytic signal filter. In addition, the density variations of the subsurface geological layers were determined by 3D inverting of the ground-based gravity data over the whole study area, and extracting this property along the route. The joint models of magnetic susceptibility and density variation could appropriately localize the traces of faults along with the geologically and tectonically structural boundaries in the region. The locations of faults correspond well to the variation of geophysical parameters on the inverted sections. Probable direction, slope and extension at depth of these faults were also determined on the sections, indicating a high tectonized zone of the Sanandaj-Sirjan Zone (SSZ) parallel to the zone of the Urumieh-Dokhtar Magmatic Assemblage (UDMA). The UDMA zone increases the magnetic and the Bouguer anomalies by intruding into the CD zone as well.

Operating temperatures of open-rack installed photovoltaic inverters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Z.; Wang, L.; Kurtz, S.

This paper presents a model for evaluating the heat-sink and component temperatures of open-rack installed photovoltaic inverters. These temperatures can be used for predicting inverter reliability. Inverter heat-sink temperatures were measured for inverters connected to three grid-connected PV (photovoltaic) test systems in Golden, Colorado, US. A model is proposed for calculating the inverter heat-sink temperature based on the ambient temperature, the ratio of the consumed power to the rated power of the inverter, and the measured wind speed. To verify and study this model, more than one year of inverter DC/AC power, irradiance, wind speed, and heat sink temperature risemore » data were collected and analyzed. The model is shown to be accurate in predicting average inverter temperatures, but will require further refinement for prediction of transient temperatures.« less

The effect of roof strength on reducing occupant injury in rollovers.

PubMed

Herbst, Brian; Forrest, Steve; Orton, Tia; Meyer, Steven E; Sances, Anthony; Kumaresan, Srirangam

2005-01-01

Roof crush occurs and potentially contributes to serious or fatal occupant injury in 26% of rollovers. It is likely that glazing retention is related to the degree of roof crush experienced in rollover accidents. Occupant ejection (including partial ejection) is the leading cause of death and injury in rollover accidents. In fatal passenger car accidents involving ejection, 34% were ejected through the side windows. Side window glass retention during a rollover is likely to significantly reduce occupant ejections. The inverted drop test methodology is a test procedure to evaluate the structural integrity of roofs under loadings similar to those seen in real world rollovers. Recent testing on many different vehicle types indicates that damage consistent with field rollover accidents can be achieved through inverted drop testing at very small drop heights. Drop test comparisons were performed on 16 pairs of vehicles representing a large spectrum of vehicle types. Each vehicle pair includes a production vehicle and a vehicle with a reinforced roof structure dropped under the same test conditions. This paper offers several examples of post-production reinforcements to roof structures that significantly increase the crush resistance of the roof as measured by inverted drop tests. These modifications were implemented with minimal impact on vehicle styling, interior space and visual clearances. The results of these modifications indicate that roof crush can be mitigated by nearly an order of magnitude, as roof crush was reduced by 44-91% with only a 1-2.3% increase in vehicle weight. Additionally, this paper analyzes the glazing breakage patterns in the moveable tempered side windows on the side adjacent to the vehicle impact point in the inverted drop tests. A comparison is made between the production vehicles and the reinforced vehicles in order to determine if the amount roof crush is related to glazing integrity in the side windows. Lastly, two drop test pairs, performed with Hybrid III test dummies, indicates that the reduction of roof crush resulted in a direct reduction in neck loading and therefore an increase in occupant protection.

Local strong slow S-wave anomalies at western edge of Pacific LLSVP

NASA Astrophysics Data System (ADS)

Obayashi, M.; Niu, F.; Yoshimitsu, J.

2017-12-01

Seismic tomography studies have revealed two broad slow shear-wave speed anomalies regions beneath the Pacific and Africa called as LLSVPs (Large Low Seismic Velocity Provinces). There are geographic correlations between the LLSVPs and hotspots, and the LLSVPs could probably play an important role for convection throughout the mantle and thermal structure and evolution of the earth. The LLSVPs have been considered to be heterogeneous in composition since the boundaries between the normal mantle are sharp. To investigate the details of the sharp LLSVP edge we measure ScS-S and SKS-S differential traveltimes in the hypocentral distance of about 60°-90° using Japanese and Chinese seismic networks. We used 25events for the Chinese network and 16 events for Japanese network that occurred in Tonga-Kermadec region and obtained 3750 event-station pairs of ScS-S and 1500 pairs of SKS-S differential travel times. We found anomalously large (more than 5 sec) ScS-S travel times accompanying normal SKS-S travel times, suggesting local strong slow region in the vicinity of the ScS bounce points (red circles in Figure 1). Such ScS bounce points locate to the northeast of New Guinea Island extending over 20 degrees in NE-SW direction. However below New Guinea Island, both ScS-S and SKS-S travel times are normal (green circles in Figure 1), indicating abrupt end of the local strong slow anomalies. We inverted the ScS-S and SKS-S differential traveltimes for lowermost mantle S-wave speed structure, assuming isotropic mantle. The result shows very strong slow anomalies of more than 5% at western edge of Pacific LLSVP that extend vertically not more than 200 km from the core mantle boundary.

Energy Harvesting for Micropower Applications by Flow-Induced Flutter of an Inverted Piezoelectric Flag

NASA Astrophysics Data System (ADS)

Shoele, Kourosh; Mittal, Rajat

2015-11-01

Piezoelectric flexible flags can be used to continuously generate energy for small-scale sensor used in a wide variety of applications ranging from measurement/monitoring of environmental conditions (outdoors or indoors) to in-situ tracking of wild animals. Here, we study the energy harvesting performance as well as the flow-structure interaction of an inverted piezoelectric flag. We use a coupled fluid-structure-electric solver to examine the dynamic response of the inverted flag as well as the associated vortical characteristics with different inertia and bending stiffness. Simulations indicate that large amplitude vibrations can be achieved over a large range of parameters over which lock-on between the flag flutter and the intrinsic wake shedding occurs. The effects of initial inclination of the flag to the prevailing flow as well as Reynolds number of the flow are explored, and the effect of piezoelectric material parameters on the energy harvesting performance of this flutter state is examined in detail. The maximum energy efficiency occurs when there is a match between the intrinsic timescales of flutter and the piezoelectric circuit. The simulations are used to formulate a scaling law that could be used to predict the energy harvesting performance of such devices. The support for this study comes from AFSOR, NSF, EPRI and Johns Hopkins E2SHI Seed Grant.

Dynamics of quiet human stance: computer simulations of a triple inverted pendulum model.

PubMed

Günther, Michael; Wagner, Heiko

2016-01-01

For decades, the biomechanical description of quiet human stance has been dominated by the single inverted pendulum (SIP) paradigm. However, in the past few years, the SIP model family has been falsified as an explanatory approach. Double inverted pendulum models have recently proven to be inappropriate. Human topology with three major leg joints suggests in a natural way to examine triple inverted pendulum (TIP) models as an appropriate approach. In this study, we focused on formulating a TIP model that can synthesise stable balancing attractors based on minimalistic sensor information and actuation complexity. The simulated TIP oscillation amplitudes are realistic in vertical direction. Along with the horizontal ankle, knee and hip positions, though, all simulated joint angle amplitudes still exceed the measured ones about threefold. It is likely that they could be eventually brought down to the physiological range by using more sensor information. The TIP systems' eigenfrequency spectra come out as another major result. The eigenfrequencies spread across about 0.1 Hz...20 Hz. Our main result is that joint stiffnesses can be reduced even below statically required values by using an active hip torque balancing strategy. When reducing mono- and bi-articular stiffnesses further down to levels threatening dynamic stability, the spectra indicate a change from torus-like (stable) to strange (chaotic) attractors. Spectra of measured ground reaction forces appear to be strange-attractor-like. We would conclude that TIP models are a suitable starting point to examine more deeply the dynamic character of and the essential structural properties behind quiet human stance. Abbreviations and technical terms Inverted pendulum body exposed to gravity and pivoting in a joint around position of unstable equilibrium (operating point) SIP single inverted pendulum: one rigid body pivoting around fixation to the ground (external joint) DIP double inverted pendulum: two bodies; external and internal joint operate around instability TIP triple inverted pendulum: three bodies; external and both internal joints operate around instability QIP quadruple inverted pendulum: four bodies, foot replaces external joint; all three internal joints operate around instability Eigenfrequency characteristic frequency that a physical system is oscillating at when externally excited at a limited energy level DOF degree of freedom; in mechanics: linear displacement or angle or combination thereof Mono-articular stiffness: coefficient of proportionality between mechanical displacement of a DOF and restoring force/torque component in the respective DOF Bi-articular stiffness coefficient of proportionality between mechanical displacement of a DOF and restoring force/torque component in another DOF GRF ground reaction force HAT segment including head, arms and trunk COM centre of mass COP centre of pressure in the plane of the force platform surface.

Three-dimensional lithospheric S wave velocity model of the NE Tibetan Plateau and western North China Craton

NASA Astrophysics Data System (ADS)

Wang, Xingchen; Li, Yonghua; Ding, Zhifeng; Zhu, Lupei; Wang, Chunyong; Bao, Xuewei; Wu, Yan

2017-08-01

We present a new 3-D lithospheric Vs model for the NE Tibetan Plateau (NETP) and the western North China Craton (NCC). First, high-frequency receiver functions (RFs) were inverted using the neighborhood algorithm to estimate the sedimentary structure beneath each station. Then a 3D Vs model with unprecedented resolution was constructed by jointly inverting RFs and Rayleigh wave dispersions. A low-velocity sedimentary layer with thicknesses varying from 2 to 10 km is present in the Yinchuan-Hetao graben, Ordos block, and western Alxa block. Velocities from the middle-lower crust to the uppermost mantle are generally high in the Ordos block and low in the Alxa block, indicating that the Alxa block is not part of the NCC. The thickened crust in southwestern Ordos block and western Alxa block suggests that they have been modified. Two crustal low-velocity zones (LVZs) were detected beneath the Kunlun Fault (KF) zone and western Qilian Terrane (QLT). The origin of the LVZ beneath the KF zone may be the combined effect of shear heating, localized asthenosphere upwelling, and crustal radioactivity. The LVZ in the western QLT, representing an early stage of the LVZ that has developed in the KF zone, acts as a decollement to decouple the deformation between the upper and lower crust and plays a key role in seismogenesis. We propose that the crustal deformation beneath the NETP is accommodated by a combination of shear motion, thickening of the upper-middle crust, and removal of lower crust.

Dynamic Hebbian Cross-Correlation Learning Resolves the Spike Timing Dependent Plasticity Conundrum.

PubMed

Olde Scheper, Tjeerd V; Meredith, Rhiannon M; Mansvelder, Huibert D; van Pelt, Jaap; van Ooyen, Arjen

2017-01-01

Spike Timing-Dependent Plasticity has been found to assume many different forms. The classic STDP curve, with one potentiating and one depressing window, is only one of many possible curves that describe synaptic learning using the STDP mechanism. It has been shown experimentally that STDP curves may contain multiple LTP and LTD windows of variable width, and even inverted windows. The underlying STDP mechanism that is capable of producing such an extensive, and apparently incompatible, range of learning curves is still under investigation. In this paper, it is shown that STDP originates from a combination of two dynamic Hebbian cross-correlations of local activity at the synapse. The correlation of the presynaptic activity with the local postsynaptic activity is a robust and reliable indicator of the discrepancy between the presynaptic neuron and the postsynaptic neuron's activity. The second correlation is between the local postsynaptic activity with dendritic activity which is a good indicator of matching local synaptic and dendritic activity. We show that this simple time-independent learning rule can give rise to many forms of the STDP learning curve. The rule regulates synaptic strength without the need for spike matching or other supervisory learning mechanisms. Local differences in dendritic activity at the synapse greatly affect the cross-correlation difference which determines the relative contributions of different neural activity sources. Dendritic activity due to nearby synapses, action potentials, both forward and back-propagating, as well as inhibitory synapses will dynamically modify the local activity at the synapse, and the resulting STDP learning rule. The dynamic Hebbian learning rule ensures furthermore, that the resulting synaptic strength is dynamically stable, and that interactions between synapses do not result in local instabilities. The rule clearly demonstrates that synapses function as independent localized computational entities, each contributing to the global activity, not in a simply linear fashion, but in a manner that is appropriate to achieve local and global stability of the neuron and the entire dendritic structure.

Inverse structure functions in the canonical wind turbine array boundary layer

NASA Astrophysics Data System (ADS)

Viggiano, Bianca; Gion, Moira; Ali, Naseem; Tutkun, Murat; Cal, Raúl Bayoán

2015-11-01

Insight into the statistical behavior of the flow past an array of wind turbines is useful in determining how to improve power extraction from the overall available energy. Considering a wind tunnel experiment, hot-wire anemometer velocity signals are obtained at the centerline of a 3 x 3 canonical wind turbine array boundary layer. Two downstream locations are considered referring to the near- and far-wake, and 21 vertical points were acquired per profile. Velocity increments are used to quantify the ordinary and inverse structure functions at both locations and their relationship between the scaling exponents is noted. It is of interest to discern if there is evidence of an inverted scaling. The inverse structure functions will also be discussed from the standpoint of the proximity to the array. Observations will also address if inverted scaling exponents follow a power law behavior and furthermore, extended self-similarity of the second moment is used to obtain the scaling exponent of other moments. Inverse structure functions of moments one through eight are tested via probability density functions and the behavior of the negative moment is investigated as well. National Science Foundation-CBET-1034581.

Three-dimensional models of P wave velocity and P-to-S velocity ratio in the southern central Andes by simultaneous inversion of local earthquake data

NASA Astrophysics Data System (ADS)

Graeber, Frank M.; Asch, Günter

1999-09-01

The PISCO'94 (Proyecto de Investigatión Sismológica de la Cordillera Occidental, 1994) seismological network of 31 digital broad band and short-period three-component seismometers was deployed in northern Chile between the Coastal Cordillera and the Western Cordillera. More than 5300 local seismic events were observed in a 100 day period. A subset of high-quality P and S arrival time data was used to invert simultaneously for hypocenters and velocity structure. Additional data from two other networks in the region could be included. The velocity models show a number of prominent anomalies, outlining an extremely thickened crust (about 70 km) beneath the forearc region, an anomalous crustal structure beneath the recent magmatic arc (Western Cordillera) characterized by very low velocities, and a high-velocity slab. A region of an increased Vp/Vs ratio has been found directly above the Wadati-Benioff zone, which might be caused by hydration processes. A zone of lower than average velocities and a high Vp/Vs ratio might correspond to the asthenospheric wedge. The upper edge of the Wadati-Benioff zone is sharply defined by intermediate depth hypocenters, while evidence for a double seismic zone can hardly be seen. Crustal events between the Precordillera and the Western Cordillera have been observed for the first time and are mainly located in the vicinity of the Salar de Atacama down to depths of about 40 km.

NREL Evaluates Advanced Solar Inverter Performance for Hawaiian Electric

Science.gov Websites

Companies | Energy Systems Integration Facility | NREL NREL Evaluates Advanced Solar Inverter Performance for Hawaiian Electric Companies NREL Evaluates Advanced Solar Inverter Performance for Hawaiian performance and impacts of today's advanced solar inverters, as well as proprietary feedback to the inverter

N channel JFET based digital logic gate structure

NASA Technical Reports Server (NTRS)

Krasowski, Michael J. (Inventor)

2010-01-01

A circuit topography is presented which is used to create usable digital logic gates using N (negatively doped) channel Junction Field Effect Transistors (JFETs) and load resistors, level shifting resistors, and supply rails whose values are based on the direct current (DC) parametric distributions of those JFETs. This method has direct application to the current state of the art in high temperature, for example 300.degree. C. to 500.degree. C. and higher, silicon carbide (SiC) device production. The ability to produce inverting and combinatorial logic enables the production of pulse and edge triggered latches. This scale of logic synthesis would bring digital logic and state machine capabilities to devices operating in extremely hot environments, such as the surface of Venus, near hydrothermal vents, within nuclear reactors (SiC is inherently radiation hardened), and within internal combustion engines. The basic logic gate can be configured as a driver for oscillator circuits allowing for time bases and simple digitizers for resistive or reactive sensors. The basic structure of this innovation, the inverter, can be reconfigured into various analog circuit topographies through the use of feedback structures.

Inverter design for high frequency power distribution

NASA Technical Reports Server (NTRS)

King, R. J.

1985-01-01

A class of simple resonantly commutated inverters are investigated for use in a high power (100 KW - 1000 KW) high frequency (10 KHz - 20 KHz) AC power distribution system. The Mapham inverter is found to provide a unique combination of large thyristor turn-off angle and good utilization factor, much better than an alternate 'current-fed' inverter. The effects of loading the Mapham inverter entirely with rectifier loads are investigated by simulation and with an experimental 3 KW 20 KHz inverter. This inverter is found to be well suited to a power system with heavy rectifier loading.

Status and Needs of Power Electronics for Photovoltaic Inverters

NASA Astrophysics Data System (ADS)

Qin, Y. C.; Mohan, N.; West, R.; Bonn, R.

2002-06-01

Photovoltaics is the utility connected distributed energy resource (DER) that is in widespread use today. It has one element, the inverter, which is common with all DER sources except rotating generators. The inverter is required to transfer dc energy to ac energy. With all the DER technologies, (solar, wind, fuel cells, and microturbines) the inverter is still an immature product that will result in reliability problems in fielded systems. Today, the PV inverter is a costly and complex component of PV systems that produce ac power. Inverter MTFF (mean time to first failure) is currently unacceptable. Low inverter reliability contributes to unreliable fielded systems and a loss of confidence in renewable technology. The low volume of PV inverters produced restricts the manufacturing to small suppliers without sophisticated research and reliability programs or manufacturing methods. Thus, the present approach to PV inverter supply has low probability of meeting DOE reliability goals.

Comparative study of SiC- and Si-based photovoltaic inverters

NASA Astrophysics Data System (ADS)

Ando, Yuji; Oku, Takeo; Yasuda, Masashi; Shirahata, Yasuhiro; Ushijima, Kazufumi; Murozono, Mikio

2017-01-01

This article reports comparative study of 150-300 W class photovoltaic inverters (Si inverter, SiC inverter 1, and SiC inverter 2). In these sub-kW class inverters, the ON-resistance was considered to have little influence on the efficiency. The developed SiC inverters, however, have exhibited an approximately 3% higher direct current (DC)-alternating current (AC) conversion efficiency as compared to the Si inverter. Power loss analysis indicated a reduction in the switching and reverse recovery losses of SiC metal-oxide-semiconductor field-effect transistors used for the DC-AC converter is responsible for this improvement. In the SiC inverter 2, an increase of the switching frequency up to 100 kHz achieved a state-of-the-art combination of the weight (1.25 kg) and the volume (1260 cm3) as a 150-250 W class inverter. Even though the increased switching frequency should cause the increase of the switching losses, the SiC inverter 2 exhibited an efficiency comparable to the SiC inverter 1 with a switching frequency of 20 kHz. The power loss analysis also indicated a decreased loss of the DC-DC converter built with SiC Schottky barrier diodes led to the high efficiency for its increased switching frequency. These results clearly indicated feasibility of SiC devices even for sub-kW photovoltaic inverters, which will be available for the applications where compactness and efficiency are of tremendous importance.

Southern Mariana OBS Experiment and Preliminary Results of Passive-Source Investigations

NASA Astrophysics Data System (ADS)

Le, B. M.; Lin, J.; Yang, T.; Shiyan 3, S. P. O. R.

2017-12-01

The Southern Mariana OBS Experiment (SMOE) was one of the first seismic experiments targeting the deepest part of Earth's surface. During the Phase I experiment in December 2016, an array of OBS instruments were deployed across the Challenger Deep that recorded both active-source and passive-source data. During the Phase II experiment in December 2016-June 2017, passive-source data were recorded. We have retrieved earthquake signals and processed the waveforms from the recorded global, regional and local events, respectively, during the Phase I experiment. Most of the waveforms recorded by the OBS array have fairly good quality with discernible main phases. Rayleigh waves from many earthquakes were analyzed using the frequency-time analysis and their group velocities at different periods were obtained. The dispersion curves from different Rayleigh wave propagating paths would be valuable for inverting the structure of the subducting Pacific and overriding Philippine Sea plates. Furthermore, we applied the ambient noise cross-correlation method and retrieved high-quality coherence surface wave waveforms. With its relatively high frequencies, the surface waves can be used to study the crustal structure of the region. Together with the Phase II data, we expect that this seismic experiment will provide unprecedented constraints on the structure and geodynamic processes of the southern Mariana trench.

Local-time survey of plasma at low altitudes over the auroral zones

NASA Technical Reports Server (NTRS)

Frank, L. A.; Ackerson, K. L.

1971-01-01

A local-time survey of the low energy proton and electron intensities precipitated into the earth's atmosphere during periods of magnetic quiescence was constructed. A typical, individual satellite crossing of this region in each of eight local-time sectors was selected from a library of similar observations with the polar-orbiting satellite Injun 5. The trapping boundary for more energetic electron intensities, E 45 keV, is a natural coordinate for delineating the boundary between the two major types of lower energy, 50 or = E or = 15,000 eV. The main contributors to electron energy influx are inverted V precipitation poleward of the trapping boundary and the plasma sheet intensities equatorward. These are interpreted in terms of a magnetospheric model.

Bioelectrochemistry II: Membrane Phenomena,

DTIC Science & Technology

1984-12-11

phosphatidic acid as a Ca ionophore, COLOSIMO (Rome) on cytochrome C, SYMONS (Rehovot) on electric field stimulated luminescence, FATO (Bologna) on...because of the hydrophobic amino acids interacting with the hydrocarbons. The formation of inverted micelles in the lipid structures that show up in

Experimental and Theoretical Results in Output Trajectory Redesign for Flexible Structures

NASA Technical Reports Server (NTRS)

Dewey, J. S.; Leang, K.; Devasia, S.

1998-01-01

In this paper we study the optimal redesign of output trajectories for linear invertible systems. This is particularly important for tracking control of flexible structures because the input-state trajectores, that achieve tracking of the required output may cause excessive vibrations in the structure. We pose and solve this problem, in the context of linear systems, as the minimization of a quadratic cost function. The theory is developed and applied to the output tracking of a flexible structure and experimental results are presented.

Performance of a Dynamically Controlled Inverter in a Photovoltaic System Interconnected with a Secondary Network Distribution System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coddington, M. H.; Kroposki, B. D.; Basso, T.

In 2008, a 300 kW{sub peak} photovoltaic (PV) system was installed on the rooftop of the Colorado Convention Center (CCC). The installation was unique for the electric utility, Xcel Energy, as it had not previously permitted a PV system to be interconnected on a building served by the local secondary network distribution system (network). The PV system was installed with several provisions; one to prevent reverse power flow, another called a dynamically controlled inverter (DCI), that curtails the output of the PV inverters to maintain an amount of load supplied by Xcel Energy at the CCC. The DCI system utilizesmore » current transformers (CTs) to sense power flow to insure that a minimum threshold is maintained from Xcel Energy through the network transformers. The inverters are set to track the load on each of the three phases and curtail power from the PV system when the generated PV system current reaches 95% of the current on any phase. This is achieved by the DCI, which gathers inputs from current transformers measuring the current from the PV array, Xcel, and the spot network load. Preventing reverse power flow is a critical technical requirement for the spot network which serve this part of the CCC. The PV system was designed with the expectation that the DCI system would not curtail the PV system, as the expected minimum load consumption was historically higher than the designed PV system size. However, the DCI system has operated many days during the course of a year, and the performance has been excellent. The DCI system at the CCC was installed as a secondary measure to insure that a minimum level of power flows to the CCC from the Xcel Energy network. While this DCI system was intended for localized control, the system could also reduce output percent if an external smart grid control signal was employed. This paper specifically focuses on the performance of the innovative design at this installation; however, the DCI system could also be used for new s- art grid-enabled distribution systems where renewables power contributions at certain conditions or times may need to be curtailed.« less

Inverting papilloma of the temporal bone: Report of four new cases and systematic review of the literature.

PubMed

Carlson, Matthew L; Sweeney, Alex D; Modest, Mara C; Van Gompel, Jamie J; Haynes, David S; Neff, Brian A

2015-11-01

Inverting papillomas (IPs) are benign locally invasive tumors that most commonly present within the sinonasal cavity. Temporal bone involvement is exceedingly rare, with fewer than 30 cases reported within the English literature to date. Case series and systematic review of the literature. Four consecutive subjects with temporal bone inverting papilloma (TBIP) were treated, and an additional 28 previously published cases were identified in the literature. Main outcome measures were disease presentation, diagnostic evaluation, management strategy, and outcome. A total of 32 cases were analyzed. The median age at diagnosis was 54 years (mean 54.1; range 19-81 years). Nineteen (59%) patients had synchronous or metachronous sinonasal IP, whereas 13 (41%) had isolated temporal bone disease without sinus involvement. Over half of the patients undergoing microsurgical resection experienced at least one recurrence. Compared to patients with a history of sinus IP, subjects with primary TBIP were younger at time of presentation (44 vs. 58 years; P=0.012); were more commonly female (62% vs. 32%; P=0.15); and were less likely to have intracranial spread (8% vs. 26%; P=0.36), cranial neuropathy (8% vs. 26%; P=0.36), human papillomavirus positivity (11% vs. 57%; P=0.11), or associated carcinoma (0% vs. 47%; P=0.004). Inverting papilloma of the lateral skull base is rare and can pose a significant therapeutic challenge. Primary lesions of the temporal bone appear to follow a less aggressive clinical course when compared to those arising in association with sinonasal disease. Gross total resection is the preferred method of treatment, when feasible, given the high rate of recurrence with subtotal resection and risk of associated malignancy. 4. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Traction Drive Inverter Cooling with Submerged Liquid Jet Impingement on Microfinned Enhanced Surfaces (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waye, S.; Narumanchi, S.; Moreno, G.

Jet impingement is one means to improve thermal management for power electronics in electric-drive traction vehicles. Jet impingement on microfin-enhanced surfaces further augments heat transfer and thermal performance. A channel flow heat exchanger from a commercial inverter was characterized as a baseline system for comparison with two new prototype designs using liquid jet impingement on plain and microfinned enhanced surfaces. The submerged jets can target areas with the highest heat flux to provide local cooling, such as areas under insulated-gate bipolar transistors and diode devices. Low power experiments, where four diodes were powered, dissipated 105 W of heat and weremore » used to validate computational fluid dynamics modeling of the baseline and prototype designs. Experiments and modeling used typical automotive flow rates using water-ethylene glycol as a coolant (50%-50% by volume). The computational fluid dynamics model was used to predict full inverter power heat dissipation. The channel flow and jet impingement configurations were tested at full inverter power of 40 to 100 kW (output power) on a dynamometer, translating to an approximate heat dissipation of 1 to 2 kW. With jet impingement, the cold plate material is not critical for the thermal pathway. A high-temperature plastic was used that could eventually be injection molded or formed, with the jets formed from a basic aluminum plate with orifices acting as nozzles. Long-term reliability of the jet nozzles and impingement on enhanced surfaces was examined. For jet impingement on microfinned surfaces, thermal performance increased 17%. Along with a weight reduction of approximately 3 kg, the specific power (kW/kg) increased by 36%, with an increase in power density (kW/L) of 12% compared with the baseline channel flow configuration.« less

Enhancement of electron injection in inverted bottom-emitting organic light-emitting diodes using Al/LiF compound thin film

NASA Astrophysics Data System (ADS)

Nie, Qu-yang; Zhang, Fang-hui

2018-05-01

The inverted bottom-emitting organic light-emitting devices (IBOLEDs) were prepared, with the structure of ITO/Al ( x nm)/LiF (1 nm)/Bphen (40 nm)/CBP: GIr1 (14%):R-4b (2%) (10 nm)/BCP (3 nm)/CBP:GIr1 (14%):R-4b (2%) (20 nm)/TCTA (10 nm)/NPB (40 nm)/MoO3 (40 nm)/Al (100 nm), where the thickness of electron injection layer Al ( x) are 0 nm, 2 nm, 3 nm, 4 nm and 5 nm, respectively. In this paper, the electron injection condition and luminance properties of inverted devices were investigated by changing the thickness of Al layer in Al/LiF compound thin film. It turns out that the introduction of Al layer can improve electron injection of the devices dramatically. Furthermore, the device exerts lower driving voltage and higher current efficiency when the thickness of electron injection Al layer is 3 nm. For example, the current efficiency of the device with 3-nm-thick Al layer reaches 19.75 cd·A-1 when driving voltage is 7 V, which is 1.24, 1.17 and 17.03 times larger than those of the devices with 2 nm, 4 nm and 5 nm Al layer, respectively. The device property reaches up to the level of corresponding conventional device. In addition, all inverted devices with electron injection Al layer show superior stability of color coordinate due to the adoption of co-evaporation emitting layer and BCP spacer-layer, and the color coordinate of the inverted device with 3-nm-thick Al layer only changes from (0.580 6, 0.405 6) to (0.532 8, 0.436 3) when driving voltage increases from 6 V to 10 V.

A novel double gate metal source/drain Schottky MOSFET as an inverter

NASA Astrophysics Data System (ADS)

Loan, Sajad A.; Kumar, Sunil; Alamoud, Abdulrahman M.

2016-03-01

In this work, we propose and simulate a novel structure of a double gate metal source/drain (MSD) Schottky MOSFET. The novelty of the proposed device is that it realizes a complete CMOS inverter action, which is actually being realized by the combination of two n and p type MOS transistors in the conventional CMOS technology. Therefore, the use of this device will significantly reduce the transistor count in implementing combinational and sequential circuits. Further, there is a significant reduction in the number of junctions and regions in the proposed device in comparison to the conventional CMOS inverter. Therefore, the proposed device is compact and can consume less power. The proposed device has been named as Sajad-Sunil-Schottky (SSS) device. The mixed mode circuit analysis of the proposed SSS device has shown that a CMOS inverter action with high logic level (VOH) and low logic level (VOL) as ∼VDD and ∼ground respectively. A two dimensional calibrated simulation study using the experimental data has revealed that the proposed SSS device in n and p type modes have subthreshold slopes (S) of 130 mV/decade and 85 mV/decade respectively and have reasonable high ION and ION/IOFF ratio's. Furthermore, it has been proved that such a device action cannot be realised by folding the conventional doped n and p MOS transistors.

Proflavine binding to poly(rC-rA) inverts the CD spectrum but not the helix handedness.

PubMed

Westhof, E; Sundaralingam, M

1984-08-01

The interaction of proflavine hemisulfate with the sodium salt of poly(rC-rA) in solution (unbuffered) yields an inverted (mirror-like) circular dichroism (CD) spectrum to that of the free poly(rC-rA). Simultaneously, an induced negative Cotton effect appears in the proflavine band region with a maximum at 467 nm and a slight shoulder at 420 nm. This observation may be explained as resulting from the formation of a poly(rC-rA).proflavine complex with the polynucleotide existing as a right-handed parallel chain duplex with the proflavine intercalated between the CpA sequence and not the ApC sequence. The intercalation geometry here is expected to be analogous to that found in the crystal structure of the dinucleotide CpA.proflavine complex (Westhof et al. J. Mol. Biol., 1981) which forms a miniature right-handed helix. Although normally an inverted spectra could be attributed to a reversal in the helix handedness, the similarity in the 31P nuclear magnetic resonance spectra between the free and proflavine bound poly(rC-rA) indicates that their handedness is the same. The inverted CD spectrum may be a result of the different stacking orientation between the intercalated proflavine and the A-A base-pair on one hand and the triply hydrogen bonded protonated C-C base-pair on the other.

Genetic and DNA sequence analysis of the kanamycin resistance transposon Tn903.

PubMed Central

Grindley, N D; Joyce, C M

1980-01-01

The kanamycin resistance transposon Tn903 consists of a unique region of about 1000 base pairs bounded by a pair of 1050-base-pair inverted repeat sequences. Each repeat contains two Pvu II endonuclease cleavage sites separated by 520 base pairs. We have constructed derivatives of Tn903 in which this 520-base-pair fragment is deleted from one or both repeats. Those derivatives that lack both 520-base-pair fragments cannot transpose, whereas those that lack just one remain transposition proficient. One such transposable derivative, Tn903 delta I, has been selected for further study. We have determined the sequence of the intact inverted repeat. The 18 base pairs at each end are identical and inverted relative to one another, a structure characteristic of insertion sequences. Additional experiments indicate that a single inverted repeat from Tn903 can, in fact, transpose; we propose that this element be called IS903. To correlate the DNA sequence with genetic activities, we have created mutations by inserting a 10-base-pair DNA fragment at several sites within the intact repeat of Tn903 delta 1, and we have examined the effect of such insertions on transposability. The results suggest that IS903 encodes a 307-amino-acid polypeptide (a "transposase") that is absolutely required for transposition of IS903 or Tn903. Images PMID:6261245

Biped Robot Gait Planning Based on 3D Linear Inverted Pendulum Model

NASA Astrophysics Data System (ADS)

Yu, Guochen; Zhang, Jiapeng; Bo, Wu

2018-01-01

In order to optimize the biped robot’s gait, the biped robot’s walking motion is simplify to the 3D linear inverted pendulum motion mode. The Center of Mass (CoM) locus is determined from the relationship between CoM and the Zero Moment Point (ZMP) locus. The ZMP locus is planned in advance. Then, the forward gait and lateral gait are simplified as connecting rod structure. Swing leg trajectory using B-spline interpolation. And the stability of the walking process is discussed in conjunction with the ZMP equation. Finally the system simulation is carried out under the given conditions to verify the validity of the proposed planning method.

A new method of Curie depth evaluation from magnetic data: Theory

NASA Technical Reports Server (NTRS)

Won, I. J. (Principal Investigator)

1981-01-01

An approach to estimating the Curie point isotherm uses the classical Gauss method inverting a system of nonlinear equations. The method, slightly modified by a differential correction technique, directly inverts filtered Magsat data to calculate the crustal structure above the Curie depth, which is modeled as a magnetized layer of varying thickness and susceptibility. Since the depth below the layer is assumed to be nonmagnetic, the bottom of the layer is interpreted as the Curie depth. The method, once fully developed, tested, and compared with previous work by others, is to be applied to a portion of the eastern U.S. when sufficient Magsat data are accumulated for the region.

Critical N = (1, 1) general massive supergravity

NASA Astrophysics Data System (ADS)

Deger, Nihat Sadik; Moutsopoulos, George; Rosseel, Jan

2018-04-01

In this paper we study the supermultiplet structure of N = (1, 1) General Massive Supergravity at non-critical and critical points of its parameter space. To do this, we first linearize the theory around its maximally supersymmetric AdS3 vacuum and obtain the full linearized Lagrangian including fermionic terms. At generic values, linearized modes can be organized as two massless and 2 massive multiplets where supersymmetry relates them in the standard way. At critical points logarithmic modes appear and we find that in three of such points some of the supersymmetry transformations are non-invertible in logarithmic multiplets. However, in the fourth critical point, there is a massive logarithmic multiplet with invertible supersymmetry transformations.

Implication of Broadband Dispersion Measurements in Constraining Upper Mantle Velocity Structures

NASA Astrophysics Data System (ADS)

Kuponiyi, A.; Kao, H.; Cassidy, J. F.; Darbyshire, F. A.; Dosso, S. E.; Gosselin, J. M.; Spence, G.

2017-12-01

Dispersion measurements from earthquake (EQ) data are traditionally inverted to obtain 1-D shear-wave velocity models, which provide information on deep earth structures. However, in many cases, EQ-derived dispersion measurements lack short-period information, which theoretically should provide details of shallow structures. We show that in at least some cases short-period information, such as can be obtained from ambient seismic noise (ASN) processing, must be combined with EQ dispersion measurements to properly constrain deeper (e.g. upper-mantle) structures. To verify this, synthetic dispersion data are generated using hypothetical velocity models under four scenarios: EQ only (with and without deep low-velocity layers) and combined EQ and ASN data (with and without deep low-velocity layers). The now "broadband" dispersion data are inverted using a trans-dimensional Bayesian framework with the aim of recovering the initial velocity models and assessing uncertainties. Our results show that the deep low-velocity layer could only be recovered from the inversion of the combined ASN-EQ dispersion measurements. Given this result, we proceed to describe a method for obtaining reliable broadband dispersion measurements from both ASN and EQ and show examples for real data. The implication of this study in the characterization of lithospheric and upper mantle structures, such as the Lithosphere-Asthenosphere Boundary (LAB), is also discussed.

Fault-tolerant three-level inverter

DOEpatents

Edwards, John; Xu, Longya; Bhargava, Brij B.

2006-12-05

A method for driving a neutral point clamped three-level inverter is provided. In one exemplary embodiment, DC current is received at a neutral point-clamped three-level inverter. The inverter has a plurality of nodes including first, second and third output nodes. The inverter also has a plurality of switches. Faults are checked for in the inverter and predetermined switches are automatically activated responsive to a detected fault such that three-phase electrical power is provided at the output nodes.

Wind seismic noise introduced by external infrastructure: field data and transfer mechanism

NASA Astrophysics Data System (ADS)

Martysevich, Pavel; Starovoyt, Yuri

2017-04-01

Background seismic noise generated by wind was analyzed at six co-located seismic and infrasound arrays with the use of the wind speed data. The main factors affecting the noise level were identified as (a) external structures as antenna towers for intrasite communication, vegetation and heavy solar panels fixtures, (b) borehole casing and (c) local lithology. The wind-induced seismic noise peaks in the spectra can be predicted by combination of inverted pendulum model for antenna towers and structures used to support solar panels, free- or clamped-tube resonance of the borehole casing and is dependent on the type of sedimentary upper layer. Observed resonance frequencies are in agreement with calculated clamped / free tube modes for towers and borehole casings. Improvement of the seismic data quality can be achieved by minimizing the impact of surrounding structures close to seismic boreholes. The need and the advantage of the borehole installation may vanish and appear to be even not necessary at locations with non-consolidated sediments because the impact of surrounding structures on seismic background may significantly deteriorate the installation quality and therefore the detection capability of the array. Several IMS arrays where the radio telemetry antennas are used for data delivery to the central site may benefit from the redesign of the intrasite communication system by its substitute with the fiber-optic net as less harmful engineering solution.

The control of apical dominance: localization of the growth region of the Pharbitis nil shoot

NASA Technical Reports Server (NTRS)

Prasad, T. K.; Cline, M. G.

1986-01-01

The growing region of the upright Pharbitis nil shoot extends over a distance 13 cm basipetal to the shoot apex. When the shoot is inverted, ethylene production in this region is greatly enhanced whereas stem elongation is significantly inhibited. This growth region is ethylene-sensitive and the restriction of its growth by shoot inversion-induced ethylene may mediate the release of apical dominance.

Photographic copy of original drawing, by Corps of Engineers, U.S. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photographic copy of original drawing, by Corps of Engineers, U.S. Army, May 1938 (original in possession of Corps of Engineers, U.S. Army, Pittsburgh District, Engineering Division files) Unit 1, lining details and typical sections of invert - Johnstown Local Flood Protection Project, Beginning on Conemaugh River approx 3.8 miles downstream from confluence of Little Conemaugh & Stony Creek Rivers at Johnstown, Johnstown, Cambria County, PA

21 CFR 184.1859 - Invert sugar.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Invert sugar. 184.1859 Section 184.1859 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1859 Invert sugar. (a) Invert sugar (CAS Reg. No. 8013-17-0) is an aqueous solution of inverted or...

Displacements of the earth's surface due to atmospheric loading - Effects of gravity and baseline measurements

NASA Technical Reports Server (NTRS)

Van Dam, T. M.; Wahr, J. M.

1987-01-01

Atmospheric mass loads and deforms the earth's crust. By performing a convolution sum between daily, global barometric pressure data and mass loading Green's functions, the time dependent effects of atmospheric loading, including those associated with short-term synoptic storms, on surface point positioning measurements and surface gravity observations are estimated. The response for both an oceanless earth and an earth with an inverted barometer ocean is calculated. Load responses for near-coastal stations are significantly affected by the inclusion of an inverted barometer ocean. Peak-to-peak vertical displacements are frequently 15-20 mm with accompanying gravity perturbations of 3-6 micro Gal. Baseline changes can be as large as 20 mm or more. The perturbations are largest at higher latitudes and during winter months. These amplitudes are consistent with the results of Rabbel and Zschau (1985), who modeled synoptic pressure disturbances as Gaussian functions of radius around a central point. Deformation can be adequately computed using real pressure data from points within about 1000 km of the station. Knowledge of local pressure, alone, is not sufficient. Rabbel and Zschau's hypothesized corrections for these displacements, which use local pressure and the regionally averaged pressure, prove accurate at points well inland but are, in general, inadequate within a few hundred kilometers of the coast.

3D Inversion of Natural Source Electromagnetics

NASA Astrophysics Data System (ADS)

Holtham, E. M.; Oldenburg, D. W.

2010-12-01

The superior depth of investigation of natural source electromagnetic techniques makes these methods excellent candidates for crustal studies as well as for mining and hydrocarbon exploration. The traditional natural source method, the magnetotelluric (MT) technique, has practical limitations because the surveys are costly and time consuming due to the labor intensive nature of ground based surveys. In an effort to continue to use the penetration advantage of natural sources, it has long been recognized that tipper data, the ratio of the local vertical magnetic field to the horizontal magnetic field, provide information about 3D electrical conductivity structure. It was this understanding that prompted the development of AFMAG (Audio Frequency Magnetics) and recently the new airborne Z-Axis Tipper Electromagnetic Technique (ZTEM). In ZTEM, the vertical component of the magnetic field is recorded above the entire survey area, while the horizontal fields are recorded at a ground-based reference station. MT processing techniques yield frequency domain transfer functions typically between 30-720 Hz that relate the vertical fields over the survey area to the horizontal fields at the reference station. The result is a cost effective procedure for collecting natural source EM data and for finding large scale targets at moderate depths. It is well known however that 1D layered structures produce zero vertical magnetic fields and thus ZTEM data cannot recover such background conductivities. This is in sharp contrast to the MT technique where electric fields are measured and a 1D background conductivity can be recovered from the off diagonal elements of the impedance tensor. While 1D models produce no vertical fields, two and three dimensional structures will produce anomalous currents and a ZTEM response. For such models the background conductivity structure does affect the data. In general however, the ZTEM data have weak sensitivity to the background conductivity and while we show that it is possible to obtain the background structure by inverting the ZTEM data alone, it is desirable to obtain robust background conductivity information from other sources. This information could come from a priori geologic and petrophysical information or from additional geophysical data such as MT. To counter the costly nature of large MT surveys and the limited sensitivity of the ZTEM technique to the background conductivity we show that an effective method is to collect and invert both MT and ZTEM data. A sparse MT survey grid can gather information about the background conductivity and deep structures while keeping the survey costs affordable. Higher spatial resolution at moderate depths can be obtained by flying multiple lines of ZTEM data.

Geometry and velocity structure of the northern Costa Rica seismogenic zone from 3D local earthquake tomography

NASA Astrophysics Data System (ADS)

Deshon, H. R.; Schwartz, S. Y.; Newman, A. V.; Dorman, L. M.; Protti, M.; Gonzalez, V.

2003-12-01

We present results of a 3D local earthquake tomography study of the Middle America Trench seismogenic zone in northern Costa Rica. Local earthquake tomography can provide constraints on the updip, downdip, and lateral variability of seismicity and P- and S-wave velocities; these constraints may in turn provide information on compositional and/or mechanical variability along the seismogenic zone. We use arrival time data recorded by the Nicoya Peninsula seismic array, part of the Costa Rica seismogenic zone experiment (CRSEIZE), a collaborative effort undertaken to better understand seismogenic behavior at the Costa Rica subduction zone using data from land and ocean bottom seismic arrays, oceanic fluid flux meters, and GPS receivers. We invert ˜10,000 P-wave and S-wave arrival times from 475 well-recorded local earthquakes (GAP < 180° , >8 P-wave arrivals) to solve for the best-fitting 1D P- and S-wave velocity models, station corrections, and hypocenters using the algorithm VELEST. These 1D velocity models are used as a starting models for 3D simultaneous inversion using the algorithm SIMULPS14. Preliminary P-wave inversions contain a positive velocity anomaly dipping beneath the Nicoya Peninsula, interpreted as the subducting Cocos Plate. Earthquakes occur in a narrow band along the slab-continent interface and are consistent with the results of Newman et al. (2002). The updip limit of seismicity occurs ˜5 km deeper and 5-10 km landward in the northern vs. the southern Nicoya Peninsula, and this shift spatially correlates to the change from Cocos-Nazca to East Pacific Rise derived oceanic plate. P-wave velocities in the upper 5-10 km of the model are consistent with the geology of the Nicoya Peninsula. We will correlate relocated microseismicity to previously noted variability in oceanic plate morphology, heat flow, fluid flow, and thermal structure and compare the resulting P- and S-wave velocity models to wide-angle refraction models and hypothesized mantle wedge compositions.

Photovoltaic system with improved DC connections and method of making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cioffi, Philip Michael; Todorovic, Maja Harfman; Herzog, Michael Scott

A micro-inverter assembly includes a housing having an opening formed in a bottom surface thereof, and a direct current (DC)-to-alternating current (AC) micro-inverter disposed within the housing at a position adjacent to the opening. The micro-inverter assembly further includes a micro-inverter DC connector electrically coupled to the DC-to-AC micro-inverter and positioned within the opening of the housing, the micro-inverter DC connector having a plurality of exposed electrical contacts.

Frequency domain model for analysis of paralleled, series-output-connected Mapham inverters

NASA Technical Reports Server (NTRS)

Brush, Andrew S.; Sundberg, Richard C.; Button, Robert M.

1989-01-01

The Mapham resonant inverter is characterized as a two-port network driven by a selected periodic voltage. The two-port model is then used to model a pair of Mapham inverters connected in series and employing phasor voltage regulation. It is shown that the model is useful for predicting power output in paralleled inverter units, and for predicting harmonic current output of inverter pairs, using standard power flow techniques. Some sample results are compared to data obtained from testing hardware inverters.

Frequency domain model for analysis of paralleled, series-output-connected Mapham inverters

NASA Technical Reports Server (NTRS)

Brush, Andrew S.; Sundberg, Richard C.; Button, Robert M.

1989-01-01

The Mapham resonant inverter is characterized as a two-port network driven by a selected periodic voltage. The two-port model is then used to model a pair of Mapham inverters connected in series and employing phasor voltage regulation. It is shown that the model is useful for predicting power output in paralleled inverter units, and for predicting harmonic current output of inverter pairs, using standard power flow techniques. Some examples are compared to data obtained from testing hardware inverters.

Status and Needs of Power Electronics for Photovoltaic Inverters: Summary Document

NASA Astrophysics Data System (ADS)

West, R.; Mauch, K.; Qin, Y. C.; Mohan, N.; Bonn, R.

2002-05-01

Photovoltaic inverters are the most mature of any DER inverter, and their mean time to first failure (MTFF) is about five years. This is an unacceptable MTFF and will inhibit the rapid expansion of PV. With all DER technologies, (solar, wind, fuel cells, and microturbines) the inverter is still an immature product that will result in reliability problems in fielded systems. The increasing need for all of these technologies to have a reliable inverter provides a unique opportunity to address these needs with focused R&D development projects. The requirements for these inverters are so similar that modular designs with universal features are obviously the best solution for a 'next generation' inverter. A 'next generation' inverter will have improved performance, higher reliability, and improved profitability. Sandia National Laboratories has estimated that the development of a 'next generation' inverter could require approximately 20 man-years of work over an 18- to 24-month time frame, and that a government-industry partnership will greatly improve the chances of success.

Single phase inverter for a three phase power generation and distribution system

NASA Technical Reports Server (NTRS)

Lindena, S. J.

1976-01-01

A breadboard design of a single-phase inverter with sinusoidal output voltage for a three-phase power generation and distribution system was developed. The three-phase system consists of three single-phase inverters, whose output voltages are connected in a delta configuration. Upon failure of one inverter the two remaining inverters will continue to deliver three-phase power. Parallel redundancy as offered by two three-phase inverters is substituted by one three-phase inverter assembly with high savings in volume, weight, components count and complexity, and a considerable increase in reliability. The following requirements must be met: (1) Each single-phase, current-fed inverter must be capable of being synchronized to a three-phase reference system such that its output voltage remains phaselocked to its respective reference voltage. (2) Each single-phase, current-fed inverter must be capable of accepting leading and lagging power factors over a range from -0.7 through 1 to +0.7.

Insights on genome size evolution from a miniature inverted repeat transposon driving a satellite DNA.

PubMed

Scalvenzi, Thibault; Pollet, Nicolas

2014-12-01

The genome size in eukaryotes does not correlate well with the number of genes they contain. We can observe this so-called C-value paradox in amphibian species. By analyzing an amphibian genome we asked how repetitive DNA can impact genome size and architecture. We describe here our discovery of a Tc1/mariner miniature inverted-repeat transposon family present in Xenopus frogs. These transposons named miDNA4 are unique since they contain a satellite DNA motif. We found that miDNA4 measured 331 bp, contained 25 bp long inverted terminal repeat sequences and a sequence motif of 119 bp present as a unique copy or as an array of 2-47 copies. We characterized the structure, dynamics, impact and evolution of the miDNA4 family and its satellite DNA in Xenopus frog genomes. This led us to propose a model for the evolution of these two repeated sequences and how they can synergize to increase genome size. Copyright © 2014 Elsevier Inc. All rights reserved.

Temperature quenching of spontaneous emission in tunnel-injection nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Talalaev, V. G., E-mail: vadimtalalaev@yandex.com; Novikov, B. V.; Cirlin, G. E.

2015-11-15

The spontaneous-emission spectra in the near-IR range (0.8–1.3 μm) from inverted tunnel-injection nanostructures are measured. These structures contain an InAs quantum-dot layer and an InGaAs quantum-well layer, separated by GaAs barrier spacer whose thickness varies in the range 3–9 nm. The temperature dependence of this emission in the range 5–295 K is investigated, both for optical excitation (photoluminescence) and for current injection in p–n junction (electroluminescence). At room temperature, current pumping proves more effective for inverted tunnel-injection nanostructures with a thin barrier (<6 nm), when the apexes of the quantum dots connect with the quantum well by narrow InGaAs strapsmore » (nanobridges). In that case, the quenching of the electroluminescence by heating from 5 to 295 K is slight. The quenching factor S{sub T} of the integrated intensity I is S{sub T} = I{sub 5}/I{sub 295} ≈ 3. The temperature stability of the emission from inverted tunnel-injection nanostructures is discussed on the basis of extended Arrhenius analysis.« less

Arachnoid membranes in the posterior half of the incisural space: an inverted Liliequist membrane-like arachnoid complex.

PubMed

Zhang, Xi-An; Qi, Song-Tao; Fan, Jun; Huang, Guang-Long; Peng, Jun-Xiang

2014-08-01

The aim of this study was to describe the similarity of configuration between the arachnoid complex in the posterior half of the incisural space and the Liliequist membrane. Microsurgical dissection and anatomical observation were performed in 20 formalin-fixed adult cadaver heads. The origin, distribution, and configuration of the arachnoid membranes and their relationships with the vascular structures in the posterior half of the incisural space were examined. The posterior perimesencephalic membrane and the cerebellar precentral membrane have a common origin at the tentorial edge and form an arachnoid complex strikingly resembling an inverted Liliequist membrane. Asymmetry between sides is not uncommon. If the cerebellar precentral membrane is hypoplastic on one side or both, the well-developed quadrigeminal membrane plays a prominent part in partitioning the subarachnoid space in the posterior half of the incisural space. The arachnoid complex in the posterior half of the incisural space can be regarded as an inverted Liliequist membrane. This concept can help neurosurgeons to gain better understanding of the surgical anatomy at the level of the tentorial incisura.

A Low-Power and In Situ Annealing Technique for the Recovery of Active Devices After Proton Irradiation

NASA Astrophysics Data System (ADS)

Francis, Laurent A.; Sedki, Amor; André, Nicolas; Kilchytska, Valéria; Gérard, Pierre; Ali, Zeeshan; Udrea, Florin; Flandre, Denis

2018-01-01

In this paper, we study the recovery of onmembrane semiconductor components, such as N-type Field-Effect Transistors (FETs) available in two different channel widths and a Complementary Metal-Oxide-Semiconductor (CMOS) inverter, after the exposure to high dose of proton radiation. Due to the ionizing effect, the electrical characteristics of the components established remarkable shifts, where the threshold voltages showed an average shift of -480 mV and -280 mV respectively for 6 μm and 24 μm N-channel transistors, likewise the inversion point of the inverter showed an important shift of -690 mV. The recovery concept is based mainly on a micro-hotplate, fabricated with backside MEMS micromachining structure and a Silicon-On-Insulator (SOI) technology, ensuring rapid, low power and in situ annealing technique, this method proved its reliability in recent works. Annealing the N-channel transistors and the inverter for 16 min with a temperature of the heater up to 385 °C, guaranteed a partial recovery of the semiconductor based components with a maximum power consumption of 66 mW.

An SCR inverter with an integral battery charger for electric vehicles

NASA Technical Reports Server (NTRS)

Thimmeach, D.

1983-01-01

The feasibility of incorporating an onboard battery charger into the inverter previously developed under a NASA contract is successfully demonstrated. The rated output power of the resulting isolated battery charger is 3.6 kW at 220 Vac with an 86 percent efficiency and a 95 percent power factor. Also achieved are improved inverter efficiency (from 90 to 93 percent at 15 kW motor shaft power), inverter peak power capability (from 26 to 34 kW), and reduced weight and volume of the combined inverter/charger package (47 kg, 49 x 44 x 24 cm). Some major conclusions are that using the inverter commutation circuitry to perform the battery charging function is advantageous, and that the input-commutated thyristor inverter has the potential to be an excellent inverter and battery charger for use in electric vehicle applications.

Covariance Matrix Estimation for the Cryo-EM Heterogeneity Problem*

PubMed Central

Katsevich, E.; Katsevich, A.; Singer, A.

2015-01-01

In cryo-electron microscopy (cryo-EM), a microscope generates a top view of a sample of randomly oriented copies of a molecule. The problem of single particle reconstruction (SPR) from cryo-EM is to use the resulting set of noisy two-dimensional projection images taken at unknown directions to reconstruct the three-dimensional (3D) structure of the molecule. In some situations, the molecule under examination exhibits structural variability, which poses a fundamental challenge in SPR. The heterogeneity problem is the task of mapping the space of conformational states of a molecule. It has been previously suggested that the leading eigenvectors of the covariance matrix of the 3D molecules can be used to solve the heterogeneity problem. Estimating the covariance matrix is challenging, since only projections of the molecules are observed, but not the molecules themselves. In this paper, we formulate a general problem of covariance estimation from noisy projections of samples. This problem has intimate connections with matrix completion problems and high-dimensional principal component analysis. We propose an estimator and prove its consistency. When there are finitely many heterogeneity classes, the spectrum of the estimated covariance matrix reveals the number of classes. The estimator can be found as the solution to a certain linear system. In the cryo-EM case, the linear operator to be inverted, which we term the projection covariance transform, is an important object in covariance estimation for tomographic problems involving structural variation. Inverting it involves applying a filter akin to the ramp filter in tomography. We design a basis in which this linear operator is sparse and thus can be tractably inverted despite its large size. We demonstrate via numerical experiments on synthetic datasets the robustness of our algorithm to high levels of noise. PMID:25699132

Joint innversion of seismic and magnetotelluric data in the Parkfield Region of California using the normalized cross-gradient constraint

USGS Publications Warehouse

Bennington, Ninfa L.; Zhang, Haijiang; Thurber, Cliff; Bedrosian, Paul A.

2015-01-01

We present jointly inverted models of P-wave velocity (Vp) and electrical resistivity for a two-dimensional profile centered on the San Andreas Fault Observatory at Depth (SAFOD). Significant structural similarity between main features of the separately inverted Vp and resistivity models is exploited by carrying out a joint inversion of the two datasets using the normalized cross-gradient constraint. This constraint favors structurally similar Vp and resistivity images that adequately fit the seismic and magnetotelluric (MT) datasets. The new inversion code, tomoDDMT, merges the seismic inversion code tomoDD and the forward modeling and sensitivity kernel subroutines of the MT inversion code OCCAM2DMT. TomoDDMT is tested on a synthetic dataset and demonstrates the code’s ability to more accurately resolve features of the input synthetic structure relative to the separately inverted resistivity and velocity models. Using tomoDDMT, we are able to resolve a number of key issues raised during drilling at SAFOD. We are able to infer the distribution of several geologic units including the Salinian granitoids, the Great Valley sequence, and the Franciscan Formation. The distribution and transport of fluids at both shallow and great depths is also examined. Low values of velocity/resistivity attributed to a feature known as the Eastern Conductor (EC) can be explained in two ways: the EC is a brine-filled, high porosity region, or this region is composed largely of clay-rich shales of the Franciscan. The Eastern Wall, which lies immediately adjacent to the EC, is unlikely to be a fluid pathway into the San Andreas Fault’s seismogenic zone due to its observed higher resistivity and velocity values.

Study of structural change in volcanic and geothermal areas using seismic tomography

NASA Astrophysics Data System (ADS)

Mhana, Najwa; Foulger, Gillian; Julian, Bruce; peirce, Christine

2014-05-01

Long Valley caldera is a large silicic volcano. It has been in a state of volcanic and seismic unrest since 1978. Farther escalation of this unrest could pose a threat to the 5,000 residents and the tens of thousands of tourists who visit the area. We have studied the crustal structure beneath 28 km X 16 km area using seismic tomography. We performed tomographic inversions for the years 2009 and 2010 with a view to differencing it with the 1997 result to look for structural changes with time and whether repeat tomography is a capable of determining the changes in structure in volcanic and geothermal reservoirs. Thus, it might provide a useful tool to monitoring physical changes in volcanoes and exploited geothermal reservoirs. Up to 600 earthquakes, selected from the best-quality events, were used for the inversion. The inversions were performed using program simulps12 [Thurber, 1983]. Our initial results show that changes in both V p and V s were consistent with the migration of CO2 into the upper 2 km or so. Our ongoing work will also invert pairs of years simultaneously using a new program, tomo4d [Julian and Foulger, 2010]. This program inverts for the differences in structure between two epochs so it can provide a more reliable measure of structural change than simply differencing the results of individual years.

Pseudo- and real-inverted metamorphism caused by the superposition and extrusion of a stack of nappes: a case study of the Southern Brasília Orogen, Brazil

NASA Astrophysics Data System (ADS)

da Motta, Rafael Gonçalves; Moraes, Renato

2017-10-01

The Southern Brasília Orogen is a Neoproterozoic belt that occurs along the southernmost border of the São Francisco Craton where the Andrelândia Nappe System represents the subducted sedimentary domain and is divided into three allochthonous groups, of which the ages and P-T conditions of metamorphism are studied here. The basal unit, the Andrelândia Nappe, exhibits an inverted metamorphic pattern. The base of the structure, composed of staurolite, garnet, biotite, kyanite, quartz, and muscovite, marks the metamorphic peak, whereas at the top, the association of the metamorphic peak does not contain staurolite. The Liberdade Nappe, the middle unit, presents a normal metamorphic pattern; its base, close to the Andrelândia Nappe, shows paragneiss with evidence of in situ partial melting, and towards the top, coarse-grained staurolite schist is found. The staurolite-out and melt-in isograds are coincident and parallel to the main foliation. Thus, the shear zone that limits the nappes is syn-metamorphic, reheating the underlying Andrelândia Nappe and influencing the establishment of metamorphic inversion. This suggestion is supported by the monazite chemical ages, which indicates that the Andrelândia Nappe metamorphic peak (586 ± 15 Ma) is younger than that of the Liberdade Nappe (622.3 ± 7.6 Ma). The upper unit, the Serra da Natureza Klippe, bears a typical high-pressure granulite mineral assemblage that is composed of kyanite, garnet, K-feldspar, rutile, and leucosome, as well as a metamorphic peak at 604.5 ± 6.1 Ma. This tectonic assembly, with inverted and non-inverted metamorphic patterns and generation of klippen structures, is consistent with exhumation models and a strong indentor located in the lower continental crust.

Microgrid and Inverter Control and Simulator Software

DOE Office of Scientific and Technical Information (OSTI.GOV)

2012-09-13

A collection of software that can simulate the operation of an inverter on a microgrid or control a real inverter. In addition, it can simulate the control of multiple nodes on a microgrid." Application: Simulation of inverters and microgrids; control of inverters on microgrids." The MMI submodule is designed to control custom inverter hardware, and to simulate that hardware. The INVERTER submodule is only the simulator code, and is of an earlier generation than the simulator in MMI. The MICROGRID submodule is an agent-based simulator of multiple nodes on a microgrid which presents a web interface. The WIND submodule producesmore » movies of wind data with a web interface.« less

Design and Implementation of nine level multilevel Inverter

NASA Astrophysics Data System (ADS)

Dhineshkumar, K.; Subramani, C.

2018-04-01

In this paper the solar based boost converter integrated Nine level multilevel inverter presented. It uses 7 switches to produce nine level output stepped waveform. The aim of the work to produce 9 level wave form using solar and boost converter. The conventional inverter has multiple sources and has 16 switches are required and also more number of voltage sources required. The proposed inverter required single solar panel and reduced number of switches and integrated boost converter which increase the input voltage of the inverter. The proposed inverter simulated and compared with R load using Mat lab and prototype model experimentally verified. The proposed inverter can be used in n number of solar applications.

System and method for regulating resonant inverters

DOEpatents

Stevanovic, Ljubisa Dragoljub [Clifton Park, NY; Zane, Regan Andrew [Superior, CO

2007-08-28

A technique is provided for direct digital phase control of resonant inverters based on sensing of one or more parameters of the resonant inverter. The resonant inverter control system includes a switching circuit for applying power signals to the resonant inverter and a sensor for sensing one or more parameters of the resonant inverter. The one or more parameters are representative of a phase angle. The resonant inverter control system also includes a comparator for comparing the one or more parameters to a reference value and a digital controller for determining timing of the one or more parameters and for regulating operation of the switching circuit based upon the timing of the one or more parameters.

Stability Assessment of a System Comprising a Single Machine and Inverter with Scalable Ratings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Brian B; Lin, Yashen; Gevorgian, Vahan

Synchronous machines have traditionally acted as the foundation of large-scale electrical infrastructures and their physical properties have formed the cornerstone of system operations. However, with the increased integration of distributed renewable resources and energy-storage technologies, there is a need to systematically acknowledge the dynamics of power-electronics inverters - the primary energy-conversion interface in such systems - in all aspects of modeling, analysis, and control of the bulk power network. In this paper, we assess the properties of coupled machine-inverter systems by studying an elementary system comprised of a synchronous generator, three-phase inverter, and a load. The inverter model is formulatedmore » such that its power rating can be scaled continuously across power levels while preserving its closed-loop response. Accordingly, the properties of the machine-inverter system can be assessed for varying ratios of machine-to-inverter power ratings. After linearizing the model and assessing its eigenvalues, we show that system stability is highly dependent on the inverter current controller and machine exciter, thus uncovering a key concern with mixed machine-inverter systems and motivating the need for next-generation grid-stabilizing inverter controls.« less

Electronic structure of antifluorite Cu{sub 2}X (X = S, Se, Te) within the modified Becke-Johnson potential plus an on-site Coulomb U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yubo; Wang, Youwei; Xi, Lili

The traditional photon absorbers Cu{sub 2−x}X (X = S, Se, and Te) have regained significant research attention in the search of earth-abundant photovoltaic materials. These moderate- and narrow-gap materials have also been shown to exhibit excellent thermoelectric properties recently. However, semimetallic band structures with inverted band orderings are predicted for antifluorite structure Cu{sub 2}X using density functional theory with the local density approximation or the generalized gradient approximation. We find that semiconducting band structures and normal band orderings can be obtained using the modified Becke-Johnson potential plus an on-site Coulomb U (the mBJ+U approach), which is consistent with our earliermore » finding for diamond-like Cu-based multinary semiconductors [Y. Zhang, J. Zhang, W. Gao, T. A. Abtew, Y. Wang, P. Zhang, and W. Zhang, J. Chem. Phys. 139, 184706 (2013)]. The trend of the chemical bonding of Cu{sub 2}X is analyzed, which shows that the positions of the valence band maximum and conduction band minimum are strongly affected by the inter-site pd and intra-site sp hybridizations, respectively. The calculated gaps of Cu{sub 2}S and Cu{sub 2}Se still seem to be underestimated compared with experimental results. We also discuss the effects of different structural phases and Cu disordering and deficiency on the bandgaps of these materials.« less

Asymptotic analysis to the effect of temperature gradient on the propagation of triple flames

NASA Astrophysics Data System (ADS)

Al-Malki, Faisal

2018-05-01

We study asymptotically in this paper the influence of the temperature gradient across the mixing layer on the propagation triple flames formed inside a porous wall channel. The study begins by formulating the problem mathematically using the thermo-diffusive model and then presents a thorough asymptotic analysis of the problem in the limit of large activation energy and thin flames. Analytical formulae for the local burning speed, the flame shape and the propagation speed in terms of the temperature gradient parameter have been derived. It was shown that varying the feed temperatures can significantly enhance the burning of the reactants up to a critical threshold, beyond which no solutions can be obtained. In addition, the study showed that increasing the temperature at the boundaries will modify the usual triple structure of the flame by inverting the upper premixed branch and extending it to the boundary, which may have great implications on the safety of the adopted combustion chambers.

Photo-induced spin and valley-dependent Seebeck effect in the low-buckled Dirac materials

NASA Astrophysics Data System (ADS)

Mohammadi, Yawar

2018-04-01

Employing the Landauer-Buttiker formula we investigate the spin and valley dependence of Seebeck effect in low-buckled Dirac materials (LBDMs), whose band structure are modulated by local application of a gate voltage and off-resonant circularly polarized light. We calculate the charge, spin and valley Seebeck coefficients of an irradiated LBDM as functions of electronic doping, light intensity and the amount of the electric field in the linear regime. Our calculation reveal that all Seebeck coefficients always shows an odd features with respect to the chemical potential. Moreover, we show that, due to the strong spin-orbit coupling in the LBDMs, the induced thermovoltage in the irradiated LBDMs is spin polarized, and can also become valley polarized if the gate voltage is applied too. It is also found that the valley (spin) polarization of the induced thermovoltage could be inverted by reversing the circular polarization of light or reversing the direction the electric field (only by reversing the circular polarization of light).

Neural mechanisms underlying sensitivity to reverse-phi motion in the fly

PubMed Central

Meier, Matthias; Serbe, Etienne; Eichner, Hubert; Borst, Alexander

2017-01-01

Optical illusions provide powerful tools for mapping the algorithms and circuits that underlie visual processing, revealing structure through atypical function. Of particular note in the study of motion detection has been the reverse-phi illusion. When contrast reversals accompany discrete movement, detected direction tends to invert. This occurs across a wide range of organisms, spanning humans and invertebrates. Here, we map an algorithmic account of the phenomenon onto neural circuitry in the fruit fly Drosophila melanogaster. Through targeted silencing experiments in tethered walking flies as well as electrophysiology and calcium imaging, we demonstrate that ON- or OFF-selective local motion detector cells T4 and T5 are sensitive to certain interactions between ON and OFF. A biologically plausible detector model accounts for subtle features of this particular form of illusory motion reversal, like the re-inversion of turning responses occurring at extreme stimulus velocities. In light of comparable circuit architecture in the mammalian retina, we suggest that similar mechanisms may apply even to human psychophysics. PMID:29261684

Neural mechanisms underlying sensitivity to reverse-phi motion in the fly.

PubMed

Leonhardt, Aljoscha; Meier, Matthias; Serbe, Etienne; Eichner, Hubert; Borst, Alexander

2017-01-01

Optical illusions provide powerful tools for mapping the algorithms and circuits that underlie visual processing, revealing structure through atypical function. Of particular note in the study of motion detection has been the reverse-phi illusion. When contrast reversals accompany discrete movement, detected direction tends to invert. This occurs across a wide range of organisms, spanning humans and invertebrates. Here, we map an algorithmic account of the phenomenon onto neural circuitry in the fruit fly Drosophila melanogaster. Through targeted silencing experiments in tethered walking flies as well as electrophysiology and calcium imaging, we demonstrate that ON- or OFF-selective local motion detector cells T4 and T5 are sensitive to certain interactions between ON and OFF. A biologically plausible detector model accounts for subtle features of this particular form of illusory motion reversal, like the re-inversion of turning responses occurring at extreme stimulus velocities. In light of comparable circuit architecture in the mammalian retina, we suggest that similar mechanisms may apply even to human psychophysics.

Ambient Observations of Aerosols, Novel Aerosol Structures, And Their Engineering Applications

NASA Astrophysics Data System (ADS)

Beres, Nicholas D.

The role of atmospheric aerosols remains a crucial issue in understanding and mitigating climate change in our world today. These particles influence the Earth by altering the Earth's delicate radiation balance, human health, and visibility. In particular, black carbon particulate matter remains the key driver in positive radiative forcing (i.e., warming) due to aerosols. Produced from the incomplete combustion of hydrocarbons, these compounds can be found in many different forms around the globe. This thesis provides an overview of three research topics: (1) the ambient characterization of aerosols in the Northern Indian Ocean, measurement techniques used, and how these aerosols influence local, regional, and global climate; (2) the exploration of novel soot superaggregate particles collected in the Northern Indian Ocean and around the globe and how the properties of these particles relate to human health and climate forcing; and (3) how aerogelated soot can be produced in a novel, one-step method utilizing an inverted flame reactor and how this material could be used in industrial settings.

Hemispheric specialization and the perception of emotion: evidence from right-handers and from inverted and non-inverted left-handers.

PubMed

Reuter-Lorenz, P A; Givis, R P; Moscovitch, M

1983-01-01

Right-handers and inverted and non-inverted left-handers viewed emotional expressions in one hemifield and, simultaneously, a neutral expression of the same poser in the other hemifield. Subjects were required to identify the side containing the affective face. Happy faces with open (i.e. salient) and closed mouth smiles and sad faces were used as stimuli. For right-handers and inverters reaction time was faster to right hemifield presentations for happy faces and to left hemifield presentations for sad faces. Non-inverters showed the reverse pattern. The saliency of the happy expressions had no effect on the magnitude and direction of asymmetry for any group. The data support the hypothesis of differential hemispheric specialization for positive and negative emotion and demonstrate opposite patterns of asymmetry in affect perception for inverted and non-inverted left-handers.

Organic-inorganic hybrid inverted photodiode with planar heterojunction for achieving low dark current and high detectivity

NASA Astrophysics Data System (ADS)

Ha, JaeUn; Yoon, Seongwon; Lee, Jong-Soo; Chung, Dae Sung

2016-03-01

In this study, the strategy of using an organic-inorganic hybrid planar heterojunction consisting of polymeric semiconductors and inorganic nanocrystals is introduced to realize a high-performance hybrid photodiode (HPD) with low dark current and high detectivity. To prevent undesired charge injection under the reverse bias condition, which is the major dark current source of the photodiode, a well-defined planar heterojunction is strategically constructed via smart solution process techniques. The optimized HPD renders a low dark current of ˜10-5 mA cm-2 at -5 V and ˜10-6 mA cm-2 at -1 V, as well as a high detectivity ˜1012 Jones across the entire visible wavelength range. Furthermore, excellent photocurrent stability is demonstrated under continuous light exposure. We believe that the solution-processed planar heterojunction with inverted structure can be an attractive alternative diode structure for fabricating high-performance HPDs, which usually suffer from high dark current issues.

Interval type-2 fuzzy PID controller for uncertain nonlinear inverted pendulum system.

PubMed

El-Bardini, Mohammad; El-Nagar, Ahmad M

2014-05-01

In this paper, the interval type-2 fuzzy proportional-integral-derivative controller (IT2F-PID) is proposed for controlling an inverted pendulum on a cart system with an uncertain model. The proposed controller is designed using a new method of type-reduction that we have proposed, which is called the simplified type-reduction method. The proposed IT2F-PID controller is able to handle the effect of structure uncertainties due to the structure of the interval type-2 fuzzy logic system (IT2-FLS). The results of the proposed IT2F-PID controller using a new method of type-reduction are compared with the other proposed IT2F-PID controller using the uncertainty bound method and the type-1 fuzzy PID controller (T1F-PID). The simulation and practical results show that the performance of the proposed controller is significantly improved compared with the T1F-PID controller. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

P-wave velocity structure beneath the northern Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Park, Y.; Kim, K.; Jin, Y.

2010-12-01

We have imaged tomographically the tree-dimensional velocity structure of the upper mantle beneath the northern Antarctic Peninsula using teleseismic P waves. The data came from the seven land stations of the Seismic Experiment in Patagonia and Antarctica (SEPA) campaigned during 1997-1999, a permanent IRIS/GSN station (PMSA), and 3 seismic stations installed at scientific bases, Esperanza (ESPZ), Jubany (JUBA), and King Sejong (KSJ), in South Shetland Islands. All of the seismic stations are located in coast area, and the signal to noise ratios (SNR) are very low. The P-wave model was inverted from 95 earthquakes resulting in 347 ray paths with P- and PKP-wave arrivals. The inverted model shows a strong low velocity anmaly beneath the Bransfield Strait, and a fast anomaly beneath the South Shetland Islands. The low velocity anomaly beneath the Bransfield might be due to a back arc extension, and the fast velocity anomaly beneath the South Shetland Islands could indicates the cold subducted slab.

DNA-directed mutations. Leading and lagging strand specificity

NASA Technical Reports Server (NTRS)

Sinden, R. R.; Hashem, V. I.; Rosche, W. A.

1999-01-01

The fidelity of replication has evolved to reproduce B-form DNA accurately, while allowing a low frequency of mutation. The fidelity of replication can be compromised, however, by defined order sequence DNA (dosDNA) that can adopt unusual or non B-DNA conformations. These alternative DNA conformations, including hairpins, cruciforms, triplex DNAs, and slipped-strand structures, may affect enzyme-template interactions that potentially lead to mutations. To analyze the effect of dosDNA elements on spontaneous mutagenesis, various mutational inserts containing inverted repeats or direct repeats were cloned in a plasmid containing a unidirectional origin of replication and a selectable marker for the mutation. This system allows for analysis of mutational events that are specific for the leading or lagging strands during DNA replication in Escherichia coli. Deletions between direct repeats, involving misalignment stabilized by DNA secondary structure, occurred preferentially on the lagging strand. Intermolecular strand switch events, correcting quasipalindromes to perfect inverted repeats, occurred preferentially during replication of the leading strand.

Interparameter trade-off quantification and reduction in isotropic-elastic full-waveform inversion: synthetic experiments and Hussar land data set application

NASA Astrophysics Data System (ADS)

Pan, Wenyong; Geng, Yu; Innanen, Kristopher A.

2018-05-01

The problem of inverting for multiple physical parameters in the subsurface using seismic full-waveform inversion (FWI) is complicated by interparameter trade-off arising from inherent ambiguities between different physical parameters. Parameter resolution is often characterized using scattering radiation patterns, but these neglect some important aspects of interparameter trade-off. More general analysis and mitigation of interparameter trade-off in isotropic-elastic FWI is possible through judiciously chosen multiparameter Hessian matrix-vector products. We show that products of multiparameter Hessian off-diagonal blocks with model perturbation vectors, referred to as interparameter contamination kernels, are central to the approach. We apply the multiparameter Hessian to various vectors designed to provide information regarding the strengths and characteristics of interparameter contamination, both locally and within the whole volume. With numerical experiments, we observe that S-wave velocity perturbations introduce strong contaminations into density and phase-reversed contaminations into P-wave velocity, but themselves experience only limited contaminations from other parameters. Based on these findings, we introduce a novel strategy to mitigate the influence of interparameter trade-off with approximate contamination kernels. Furthermore, we recommend that the local spatial and interparameter trade-off of the inverted models be quantified using extended multiparameter point spread functions (EMPSFs) obtained with pre-conditioned conjugate-gradient algorithm. Compared to traditional point spread functions, the EMPSFs appear to provide more accurate measurements for resolution analysis, by de-blurring the estimations, scaling magnitudes and mitigating interparameter contamination. Approximate eigenvalue volumes constructed with stochastic probing approach are proposed to evaluate the resolution of the inverted models within the whole model. With a synthetic Marmousi model example and a land seismic field data set from Hussar, Alberta, Canada, we confirm that the new inversion strategy suppresses the interparameter contamination effectively and provides more reliable density estimations in isotropic-elastic FWI as compared to standard simultaneous inversion approach.

Effects of task and age on the magnitude and structure of force fluctuations: insights into underlying neuro-behavioral processes.

PubMed

Vieluf, Solveig; Temprado, Jean-Jacques; Berton, Eric; Jirsa, Viktor K; Sleimen-Malkoun, Rita

2015-03-13

The present study aimed at characterizing the effects of increasing (relative) force level and aging on isometric force control. To achieve this objective and to infer changes in the underlying control mechanisms, measures of information transmission, as well as magnitude and time-frequency structure of behavioral variability were applied to force-time-series. Older adults were found to be weaker, more variable, and less efficient than young participants. As a function of force level, efficiency followed an inverted-U shape in both groups, suggesting a similar organization of the force control system. The time-frequency structure of force output fluctuations was only significantly affected by task conditions. Specifically, a narrower spectral distribution with more long-range correlations and an inverted-U pattern of complexity changes were observed with increasing force level. Although not significant older participants displayed on average a less complex behavior for low and intermediate force levels. The changes in force signal's regularity presented a strong dependence on time-scales, which significantly interacted with age and condition. An inverted-U profile was only observed for the time-scale relevant to the sensorimotor control process. However, in both groups the peak was not aligned with the optimum of efficiency. Our results support the view that behavioral variability, in terms of magnitude and structure, has a functional meaning and affords non-invasive markers of the adaptations of the sensorimotor control system to various constraints. The measures of efficiency and variability ought to be considered as complementary since they convey specific information on the organization of control processes. The reported weak age effect on variability and complexity measures suggests that the behavioral expression of the loss of complexity hypothesis is not as straightforward as conventionally admitted. However, group differences did not completely vanish, which suggests that age differences can be more or less apparent depending on task properties and whether difficulty is scaled in relative or absolute terms.

Natural microseismicity investigated using double-difference tomography: a 3D look at the 2008 swarm in the Novy Kostel area, Czech Republic

NASA Astrophysics Data System (ADS)

Alexandrakis, C.; Calo, M.; Bouchaala, F.; Vavrycuk, V.

2012-04-01

The Novy Kostel region in West Bohemia is an area prone to periodic bursts of natural microseismic activity. In this study, we use 476 events from the October 2008 earthquake swarm recorded on the WEBNET seismic network. The foci occurred on the northern extension of the Marianske-Lazne Fault near the town of Novy Kostel in the Czech Republic. Initial source locations indicated a rupture zone approximately 3 km along the fault with the sources spread over 4 km depth, centered at 9 km. We use the double-difference tomography method to study the fault structure by relocating the sources and inverting for the P and S velocities in the rupture region. Events are first relocated using the HypoDD program (Waldhauser and Ellsworth, 2000) using both catalog and cross-correlated datasets. These datasets, along with the absolute time picks are then used by the TomoDD program (Zhang and Thurber, 2003) to iteratively relocate the sources and invert for the 3D seismic structure. This dataset is ideal for this procedure as the cluster is very condensed and the WEBNET network offers ray coverage in all directions. The relocated events flatten onto a fault plane striking at 169 degrees NE. This fault plane has three sections with distinct dip angles. At the shallowest (up to 8 km) and deepest (10 - 11 km) parts of the fault, the dip is shallow, whereas the middle section has a steep dip angle. Most events occur at the deeper part of the middle section. The inverted velocities correspond well to results from regional seismic refraction surveys (e.g., CELEBRATION 2000). Here, more details of the 3D velocity structure are revealed. As expected, velocities to the east of the fault are overall higher, corresponding to the uplifted northern margin of the Eger Rift. Finer structures surrounding the source region are also resolved.

Voltage balanced multilevel voltage source converter system

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

1997-01-01

A voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means.

Voltage balanced multilevel voltage source converter system

DOEpatents

Peng, F.Z.; Lai, J.S.

1997-07-01

Disclosed is a voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means. 15 figs.

Inverting near-surface models from virtual-source gathers (SM Division Outstanding ECS Award Lecture)

NASA Astrophysics Data System (ADS)

Ruigrok, Elmer; Vossen, Caron; Paulssen, Hanneke

2017-04-01

The Groningen gas field is a massive natural gas accumulation in the north-east of the Netherlands. Decades of production have led to significant compaction of the reservoir rock. The (differential) compaction is thought to have reactivated existing faults and to be the main driver of induced seismicity. The potential damage at the surface is largely affected by the state of the near surface. Thin and soft sedimentary layers can lead to large amplifications. By measuring the wavefield at different depth levels, near-surface properties can directly be estimated from the recordings. Seismicity in the Groningen area is monitored primarily with an array of vertical arrays. In the nineties a network of 8 boreholes was deployed. Since 2015, this network has been expanded with 70 new boreholes. Each new borehole consists of an accelerometer at the surface and four downhole geophones with a vertical spacing of 50 m. We apply seismic interferometry to local seismicity, for each borehole individually. Doing so, we obtain the responses as if there were virtual sources at the lowest geophones and receivers at the other depth levels. From the retrieved direct waves and reflections, we invert for P- & S- velocity and Q models. We discuss different implementations of seismic interferometry and the subsequent inversion. The inverted near-surface properties are used to improve both the source location and the hazard assessment.

Neural correlates of cognitive aging during the perception of facial age: the role of relatively distant and local texture information

PubMed Central

Komes, Jessica; Schweinberger, Stefan R.; Wiese, Holger

2015-01-01

Previous event-related potential (ERP) research revealed that older relative to younger adults show reduced inversion effects in the N170 (with more negative amplitudes for inverted than upright faces), suggestive of impairments in face perception. However, as these studies used young to middle-aged faces only, this finding may reflect preferential processing of own- relative to other-age faces rather than age-related decline. We conducted an ERP study in which young and older participants categorized young and old upright or inverted faces by age. Stimuli were presented either unfiltered or low-pass filtered at 30, 20, or 10 cycles per image (CPI). Response times revealed larger inversion effects, with slower responses for inverted faces, for young faces in young participants. Older participants did not show a corresponding effect. ERPs yielded a trend toward reduced N170 inversion effects in older relative to younger adults independent of face age. Moreover, larger inversion effects for young relative to old faces were detected, and filtering resulted in smaller N170 amplitudes. The reduced N170 inversion effect in older adults may reflect age-related changes in neural correlates of face perception. A smaller N170 inversion effect for old faces may indicate that facial changes with age hamper early face perception stages. PMID:26441790

Quantum-classical correspondence for the inverted oscillator

NASA Astrophysics Data System (ADS)

Maamache, Mustapha; Ryeol Choi, Jeong

2017-11-01

While quantum-classical correspondence for a system is a very fundamental problem in modern physics, the understanding of its mechanism is often elusive, so the methods used and the results of detailed theoretical analysis have been accompanied by active debate. In this study, the differences and similarities between quantum and classical behavior for an inverted oscillator have been analyzed based on the description of a complete generalized Airy function-type quantum wave solution. The inverted oscillator model plays an important role in several branches of cosmology and particle physics. The quantum wave packet of the system is composed of many sub-packets that are localized at different positions with regular intervals between them. It is shown from illustrations of the probability density that, although the quantum trajectory of the wave propagation is somewhat different from the corresponding classical one, the difference becomes relatively small when the classical excitation is sufficiently high. We have confirmed that a quantum wave packet moving along a positive or negative direction accelerates over time like a classical wave. From these main interpretations and others in the text, we conclude that our theory exquisitely illustrates quantum and classical correspondence for the system, which is a crucial concept in quantum mechanics. Supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2016R1D1A1A09919503)

Au nanorods-incorporated plasmonic-enhanced inverted organic solar cells

NASA Astrophysics Data System (ADS)

Peng, Ling; Mei, Yang; Chen, Shu-Fen; Zhang, Yu-Pei; Hao, Jing-Yu; Deng, Ling-Ling; Huang, Wei

2015-11-01

The effect of Au nanorods (NRs) on optical-to-electric conversion efficiency is investigated in inverted polymer solar cells, in which Au NRs are sandwiched between two layers of ZnO. Accompanied by the optimization of thickness of ZnO covered on Au NRs, a high-power conversion efficiency of 3.60% and an enhanced short-circuit current density (JSC) of 10.87 mA/cm2 are achieved in the poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC60BM)-based inverted cell and the power conversion efficiency (PCE) is enhanced by 19.6% compared with the control device. The detailed analyses of the light absorption characteristics, the simulated scattering induced by Au NRs, and the electromagnetic field around Au NRs show that the absorption improvement in the photoactive layer due to the light scattering from the longitudinal axis and the near-field increase around Au NRs induced by localized surface plasmon resonance plays a key role in enhancing the performances. Project supported by the Ministry of Science and Technology, China (Grant No. 2012CB933301), the National Natural Science Foundation of China (Grant Nos. 61274065, 51173081, 61136003, BZ2010043, 51372119, and 51172110), and the Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions and Synergetic Innovation Center for Organic Electronics and Information Displays, China.

Multilevel cascade voltage source inverter with seperate DC sources

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

1997-01-01

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Multilevel cascade voltage source inverter with seperate DC sources

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

2002-01-01

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Multilevel cascade voltage source inverter with seperate DC sources

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

2001-04-03

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Multilevel cascade voltage source inverter with separate DC sources

DOEpatents

Peng, F.Z.; Lai, J.S.

1997-06-24

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations. 15 figs.

Tomographic inversion of P-wave velocity and Q structures beneath the Kirishima volcanic complex, Southern Japan, based on finite difference calculations of complex traveltimes

USGS Publications Warehouse

Tomatsu, T.; Kumagai, H.; Dawson, P.B.

2001-01-01

We estimate the P-wave velocity and attenuation structures beneath the Kirishima volcanic complex, southern Japan, by inverting the complex traveltimes (arrival times and pulse widths) of waveform data obtained during an active seismic experiment conducted in 1994. In this experiment, six 200-250 kg shots were recorded at 163 temporary seismic stations deployed on the volcanic complex. We use first-arrival times for the shots, which were hand-measured interactively. The waveform data are Fourier transformed into the frequency domain and analysed using a new method based on autoregressive modelling of complex decaying oscillations in the frequency domain to determine pulse widths for the first-arrival phases. A non-linear inversion method is used to invert 893 first-arrival times and 325 pulse widths to estimate the velocity and attenuation structures of the volcanic complex. Wavefronts for the inversion are calculated with a finite difference method based on the Eikonal equation, which is well suited to estimating the complex traveltimes for the structures of the Kirishima volcano complex, where large structural heterogeneities are expected. The attenuation structure is derived using ray paths derived from the velocity structure. We obtain 3-D velocity and attenuation structures down to 1.5 and 0.5 km below sea level, respectively. High-velocity pipe-like structures with correspondingly low attenuation are found under the summit craters. These pipe-like structures are interpreted as remnant conduits of solidified magma. No evidence of a shallow magma chamber is visible in the tomographic images.

Inverted edge effects on carbon stocks in human-dominated landscapes

NASA Astrophysics Data System (ADS)

Romitelli, I.; Keller, M.; Vieira, S. A.; Metzger, J. P.; Reverberi Tambosi, L.

2017-12-01

Although the importance of tropical forests to regulate greenhouse gases is well documented, little is known about what factors affect the ability of these forests to store carbon in human-dominated landscapes. Among those factors, the landscape structure, particularly the amount of forest cover, the type of matrix and edge effects, can have important roles. We tested how carbon stock is influenced by a combination of factors of landscape composition (pasture and forest cover), landscape configuration (edge effect) and relief factors (slope, elevation and aspect). To test those relationships, we performed a robust carbon stock estimation with inventory and LiDAR data in human-dominated landscapes from the Brazilian Atlantic forest region. The study area showed carbon stock mean 45.49 ± 9.34 Mg ha-1. The interaction between forest cover, edge effect and slope was the best combination explanatory of carbon stock. We observed an inverted edge effect pattern where carbon stock is higher close to the edges of the studied secondary forests. This inverted edge effect observed contradicts the usual pattern reported in the literature for mature forests. We suppose this pattern is related with a positive effect that edge conditions can have stimulating forest regeneration, but the underlying processes to explain the observed pattern should still be tested. Those results suggest that Carbon stocks in human-dominated and fragmented landscapes can be highly affected by the landscape structure, and particularly that edges conditions can favor carbon sequestration in regenerating tropical forests.

Evidence for large inversion polymorphisms in the human genome from HapMap data

PubMed Central

Bansal, Vikas; Bashir, Ali; Bafna, Vineet

2007-01-01

Knowledge about structural variation in the human genome has grown tremendously in the past few years. However, inversions represent a class of structural variation that remains difficult to detect. We present a statistical method to identify large inversion polymorphisms using unusual Linkage Disequilibrium (LD) patterns from high-density SNP data. The method is designed to detect chromosomal segments that are inverted (in a majority of the chromosomes) in a population with respect to the reference human genome sequence. We demonstrate the power of this method to detect such inversion polymorphisms through simulations done using the HapMap data. Application of this method to the data from the first phase of the International HapMap project resulted in 176 candidate inversions ranging from 200 kb to several megabases in length. Our predicted inversions include an 800-kb polymorphic inversion at 7p22, a 1.1-Mb inversion at 16p12, and a novel 1.2-Mb inversion on chromosome 10 that is supported by the presence of two discordant fosmids. Analysis of the genomic sequence around inversion breakpoints showed that 11 predicted inversions are flanked by pairs of highly homologous repeats in the inverted orientation. In addition, for three candidate inversions, the inverted orientation is represented in the Celera genome assembly. Although the power of our method to detect inversions is restricted because of inherently noisy LD patterns in population data, inversions predicted by our method represent strong candidates for experimental validation and analysis. PMID:17185644

Impacts of Inverter-Based Advanced Grid Support Functions on Islanding Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Austin; Hoke, Anderson; Miller, Brian

A long-standing requirement for inverters paired with distributed energy resources is that they are required to disconnect from the electrical power system (EPS) when an electrical island is formed. In recent years, advanced grid support controls have been developed for inverters to provide voltage and frequency support by integrating functions such as voltage and frequency ride-through, volt-VAr control, and frequency-Watt control. With these new capabilities integrated into the inverter, additional examination is needed to determine how voltage and frequency support will impact pre-existing inverter functions like island detection. This paper inspects how advanced inverter functions will impact its ability tomore » detect the formation of an electrical island. Results are presented for the unintentional islanding laboratory tests of three common residential-scale photovoltaic inverters performing various combinations of grid support functions. For the inverters tested, grid support functions prolonged island disconnection times slightly; however, it was found that in all scenarios the inverters disconnected well within two seconds, the limit imposed by IEEE Std 1547-2003.« less

Mass change distribution inverted from space-borne gravimetric data using a Monte Carlo method

NASA Astrophysics Data System (ADS)

Zhou, X.; Sun, X.; Wu, Y.; Sun, W.

2017-12-01

Mass estimate plays a key role in using temporally satellite gravimetric data to quantify the terrestrial water storage change. GRACE (Gravity Recovery and Climate Experiment) only observes the low degree gravity field changes, which can be used to estimate the total surface density or equivalent water height (EWH) variation, with a limited spatial resolution of 300 km. There are several methods to estimate the mass variation in an arbitrary region, such as averaging kernel, forward modelling and mass concentration (mascon). Mascon method can isolate the local mass from the gravity change at a large scale through solving the observation equation (objective function) which represents the relationship between unknown masses and the measurements. To avoid the unreasonable local mass inverted from smoothed gravity change map, regularization has to be used in the inversion. We herein give a Markov chain Monte Carlo (MCMC) method to objectively determine the regularization parameter for the non-negative mass inversion problem. We first apply this approach to the mass inversion from synthetic data. Result show MCMC can effectively reproduce the local mass variation taking GRACE measurement error into consideration. We then use MCMC to estimate the ground water change rate of North China Plain from GRACE gravity change rate from 2003 to 2014 under a supposition of the continuous ground water loss in this region. Inversion result show that the ground water loss rate in North China Plain is 7.6±0.2Gt/yr during past 12 years which is coincident with that from previous researches.

Crocodilian Nest in a Late Cretaceous Sauropod Hatchery from the Type Lameta Ghat Locality, Jabalpur, India

PubMed Central

Srivastava, Rahul; Patnaik, Rajeev; Shukla, U. K.; Sahni, Ashok

2015-01-01

The well-known Late Cretaceous Lameta Ghat locality (Jabalpur, India) provides a window of opportunity to study a large stable, near shore sandy beach, which was widely used by sauropod dinosaurs as a hatchery. In this paper, we revisit the eggs and eggshell fragments previously assigned to lizards from this locality and reassign them to crocodylomorphs. Several features point to a crocodilian affinity, including a subspherical to ellipsoidal shape, smooth, uneven external surface, discrete trapezoid shaped shell units with wide top and narrow base, basal knobs and wedge shaped crystallites showing typical inverted triangular extinction under crossed nicols. The crocodylomorph eggshell material presented in this paper adds to the skeletal data of these most probably Cretaceous-Eocene dryosaurid crocodiles. PMID:26641665

Local Voltage Control in Distribution Networks: A Game-Theoretic Perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xinyang; Tian, Jie; Chen, Lijun

Inverter-based voltage regulation is gaining importance to alleviate emerging reliability and power-quality concerns related to distribution systems with high penetration of photovoltaic (PV) systems. This paper seeks contribution in the domain of reactive power compensation by establishing stability of local Volt/VAr controllers. In lieu of the approximate linear surrogate used in the existing work, the paper establishes existence and uniqueness of an equilibrium point using nonlinear AC power flow model. Key to this end is to consider a nonlinear dynamical system with non-incremental local Volt/VAr control, cast the Volt/VAr dynamics as a game, and leverage the fixed-point theorem as wellmore » as pertinent contraction mapping argument. Numerical examples are provided to complement the analytical results.« less

Local Voltage Control in Distribution Networks: A Game-Theoretic Perspective: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xinyang; Tian, Jie; Chen, Lijun

Inverter-based voltage regulation is gaining importance to alleviate emerging reliability and power-quality concerns related to distribution systems with high penetration of photovoltaic (PV) systems. This paper seeks contribution in the domain of reactive power compensation by establishing stability of local Volt/VAr controllers. In lieu of the approximate linear surrogate used in the existing work, the paper establishes existence and uniqueness of an equilibrium point using nonlinear AC power flow model. Key to this end is to consider a nonlinear dynamical system with non-incremental local Volt/VAr control, cast the Volt/VAr dynamics as a game, and leverage the fixed-point theorem as wellmore » as pertinent contraction mapping argument. Numerical examples are provided to complement the analytical results.« less

The whole chloroplast genome of wild rice (Oryza australiensis).

PubMed

Wu, Zhiqiang; Ge, Song

2016-01-01

The whole chloroplast genome of wild rice (Oryza australiensis) is characterized in this study. The genome size is 135,224  bp, exhibiting a typical circular structure including a pair of 25,776  bp inverted repeats (IRa,b) separated by a large single-copy region (LSC) of 82,212  bp and a small single-copy region (SSC) of 12,470  bp. The overall GC content of the genome is 38.95%. 110 unique genes were annotated, including 76 protein-coding genes, 4 ribosomal RNA genes, and 30t RNA genes. Among these, 18 are duplicated in the inverted repeat regions, 13 genes contain one intron, and 2 genes (rps12 and ycf3) have two introns.

Evidence of an inverted hexagonal phase in self-assembled phospholipid-DNA-metal complexes

NASA Astrophysics Data System (ADS)

Francescangeli, O.; Pisani, M.; Stanic, V.; Bruni, P.; Weiss, T. M.

2004-08-01

We report the first observation of an inverted hexagonal phase of phospholipid-DNA-metal complexes. These ternary complexes are formed in a self-assembled manner when water solutions of neutral lipid dioleoylphosphatidylethanolamine (DOPE), DNA and divalent metal cations (Me2+; Me=Fe, Co, Mg, Mn) are mixed, which represents a striking example of supramolecular chemistry. The structure, derived from synchrotron X-ray diffraction, consists of cylindrical DNA strands coated by neutral lipid monolayers and arranged on a two-dimensional hexagonal lattice (HIIc). Besides the fundamental aspects, DOPE-DNA-Me2+ complexes may be of great interest as efficient nonviral delivery systems in gene therapy applications because of the low inherent cytotoxicity and the potential high transfection efficiency.

The complete chloroplast genome of salt cress (Eutrema salsugineum).

PubMed

Guo, Xinyi; Hao, Guoqian; Ma, Tao

2016-07-01

The complete chloroplast (cp) sequence of the salt cress (Eutrema salsugineum), a plant well-adapted to salt stress, was presented in this study. The circular molecule is 153,407 bp in length and exhibit a typical quadripartite structure containing an 83,894 bp large single copy (LSC) region, a 17,607 bp small single copy (SSC) region, and the two 25,953 bp inverted repeats (IRs). The salt cress cp genome contains 135 known genes, including 87 protein-coding genes, 8 ribosomal RNA genes, and 40 tRNA genes; 21 of these are located in the inverted repeat region. As expected, phylogenetic analysis support the idea that E. salsugineum is sister to Brassiceae species within the Brassicaceae family.

Selective Dirac voltage engineering of individual graphene field-effect transistors for digital inverter and frequency multiplier integrations

NASA Astrophysics Data System (ADS)

Sul, Onejae; Kim, Kyumin; Jung, Yungwoo; Choi, Eunsuk; Lee, Seung-Beck

2017-09-01

The ambipolar band structure of graphene presents unique opportunities for novel electronic device applications. A cycle of gate voltage sweep in a conventional graphene transistor produces a frequency-doubled output current. To increase the frequency further, we used various graphene doping control techniques to produce Dirac voltage engineered graphene channels. The various surface treatments and substrate conditions produced differently doped graphene channels that were integrated on a single substrate and multiple Dirac voltages were observed by applying a single gate voltage sweep. We applied the Dirac voltage engineering techniques to graphene field-effect transistors on a single chip for the fabrication of a frequency multiplier and a logic inverter demonstrating analog and digital circuit application possibilities.

Design and realization of an autonomous solar system

NASA Astrophysics Data System (ADS)

Gaga, A.; Diouri, O.; Es-sbai, N.; Errahimi, F.

2017-03-01

The aim of this work is the design and realization of an autonomous solar system, with MPPT control, a regulator charge/discharge of batteries, an H-bridge multi-level inverter with acquisition system and supervising based on a microcontroller. The proposed approach is based on developing a software platform in the LabVIEW environment which gives the system a flexible structure for controlling, monitoring and supervising the whole system in real time while providing power maximization and best quality of energy conversion from DC to AC power. The reliability of the proposed solar system is validated by the simulation results on PowerSim and experimental results achieved with a solar panel, a Lead acid battery, solar regulator and an H-bridge cascaded topology of single-phase inverter.

Selective Dirac voltage engineering of individual graphene field-effect transistors for digital inverter and frequency multiplier integrations.

PubMed

Sul, Onejae; Kim, Kyumin; Jung, Yungwoo; Choi, Eunsuk; Lee, Seung-Beck

2017-09-15

The ambipolar band structure of graphene presents unique opportunities for novel electronic device applications. A cycle of gate voltage sweep in a conventional graphene transistor produces a frequency-doubled output current. To increase the frequency further, we used various graphene doping control techniques to produce Dirac voltage engineered graphene channels. The various surface treatments and substrate conditions produced differently doped graphene channels that were integrated on a single substrate and multiple Dirac voltages were observed by applying a single gate voltage sweep. We applied the Dirac voltage engineering techniques to graphene field-effect transistors on a single chip for the fabrication of a frequency multiplier and a logic inverter demonstrating analog and digital circuit application possibilities.

Integral inverter/battery charger for use in electric vehicles

NASA Technical Reports Server (NTRS)

Thimmesch, D.

1983-01-01

The design and test results of a thyristor based inverter/charger are discussed. A battery charger is included integral to the inverter by using a subset of the inverter power circuit components. The resulting charger provides electrical isolation between the vehicle propulsion battery and ac line and is capable of charging a 25 kWh propulsion battery in 8 hours from a 220 volt ac line. The integral charger employs the inverter commutation components at a resonant ac/dc isolated converter rated at 3.6 kW. Charger efficiency and power factor at an output power of 3.6 kW are 86% and 95% respectively. The inverter, when operated with a matching polyphase ac induction motor and nominal 132 volt propulsion battery, can provide a peak shaft power of 34 kW (45 ph) during motoring operation and 45 kW (60 hp) during regeneration. Thyristors are employed for the inverter power switching devices and are arranged in an input-commutated topology. This configuration requires only two thyristors to commutate the six main inverter thyristors. Inverter efficiency during motoring operation at motor shaft speeds above 450 rad/sec (4300 rpm) is 92-94% for output power levels above 11 KW (15 hp). The combined ac inverter/charger package weighs 47 kg (103 lbs).

An Optimal Current Controller Design for a Grid Connected Inverter to Improve Power Quality and Test Commercial PV Inverters.

PubMed

Algaddafi, Ali; Altuwayjiri, Saud A; Ahmed, Oday A; Daho, Ibrahim

2017-01-01

Grid connected inverters play a crucial role in generating energy to be fed to the grid. A filter is commonly used to suppress the switching frequency harmonics produced by the inverter, this being passive, and either an L- or LCL-filter. The latter is smaller in size compared to the L-filter. But choosing the optimal values of the LCL-filter is challenging due to resonance, which can affect stability. This paper presents a simple inverter controller design with an L-filter. The control topology is simple and applied easily using traditional control theory. Fast Fourier Transform analysis is used to compare different grid connected inverter control topologies. The modelled grid connected inverter with the proposed controller complies with the IEEE-1547 standard, and total harmonic distortion of the output current of the modelled inverter has been just 0.25% with an improved output waveform. Experimental work on a commercial PV inverter is then presented, including the effect of strong and weak grid connection. Inverter effects on the resistive load connected at the point of common coupling are presented. Results show that the voltage and current of resistive load, when the grid is interrupted, are increased, which may cause failure or damage for connecting appliances.

An Optimal Current Controller Design for a Grid Connected Inverter to Improve Power Quality and Test Commercial PV Inverters

PubMed Central

Altuwayjiri, Saud A.; Ahmed, Oday A.; Daho, Ibrahim

2017-01-01

Grid connected inverters play a crucial role in generating energy to be fed to the grid. A filter is commonly used to suppress the switching frequency harmonics produced by the inverter, this being passive, and either an L- or LCL-filter. The latter is smaller in size compared to the L-filter. But choosing the optimal values of the LCL-filter is challenging due to resonance, which can affect stability. This paper presents a simple inverter controller design with an L-filter. The control topology is simple and applied easily using traditional control theory. Fast Fourier Transform analysis is used to compare different grid connected inverter control topologies. The modelled grid connected inverter with the proposed controller complies with the IEEE-1547 standard, and total harmonic distortion of the output current of the modelled inverter has been just 0.25% with an improved output waveform. Experimental work on a commercial PV inverter is then presented, including the effect of strong and weak grid connection. Inverter effects on the resistive load connected at the point of common coupling are presented. Results show that the voltage and current of resistive load, when the grid is interrupted, are increased, which may cause failure or damage for connecting appliances. PMID:28540362

Large-Signal Lyapunov-Based Stability Analysis of DC/AC Inverters and Inverter-Based Microgrids

NASA Astrophysics Data System (ADS)

Kabalan, Mahmoud

Microgrid stability studies have been largely based on small-signal linearization techniques. However, the validity and magnitude of the linearization domain is limited to small perturbations. Thus, there is a need to examine microgrids with large-signal nonlinear techniques to fully understand and examine their stability. Large-signal stability analysis can be accomplished by Lyapunov-based mathematical methods. These Lyapunov methods estimate the domain of asymptotic stability of the studied system. A survey of Lyapunov-based large-signal stability studies showed that few large-signal studies have been completed on either individual systems (dc/ac inverters, dc/dc rectifiers, etc.) or microgrids. The research presented in this thesis addresses the large-signal stability of droop-controlled dc/ac inverters and inverter-based microgrids. Dc/ac power electronic inverters allow microgrids to be technically feasible. Thus, as a prelude to examining the stability of microgrids, the research presented in Chapter 3 analyzes the stability of inverters. First, the 13 th order large-signal nonlinear model of a droop-controlled dc/ac inverter connected to an infinite bus is presented. The singular perturbation method is used to decompose the nonlinear model into 11th, 9th, 7th, 5th, 3rd and 1st order models. Each model ignores certain control or structural components of the full order model. The aim of the study is to understand the accuracy and validity of the reduced order models in replicating the performance of the full order nonlinear model. The performance of each model is studied in three different areas: time domain simulations, Lyapunov's indirect method and domain of attraction estimation. The work aims to present the best model to use in each of the three domains of study. Results show that certain reduced order models are capable of accurately reproducing the performance of the full order model while others can be used to gain insights into those three areas of study. This will enable future studies to save computational effort and produce the most accurate results according to the needs of the study being performed. Moreover, the effect of grid (line) impedance on the accuracy of droop control is explored using the 5th order model. Simulation results show that traditional droop control is valid up to R/X line impedance value of 2. Furthermore, the 3rd order nonlinear model improves the currently available inverter-infinite bus models by accounting for grid impedance, active power-frequency droop and reactive power-voltage droop. Results show the 3rd order model's ability to account for voltage and reactive power changes during a transient event. Finally, the large-signal Lyapunov-based stability analysis is completed for a 3 bus microgrid system (made up of 2 inverters and 1 linear load). The thesis provides a systematic state space large-signal nonlinear mathematical modeling method of inverter-based microgrids. The inverters include the dc-side dynamics associated with dc sources. The mathematical model is then used to estimate the domain of asymptotic stability of the 3 bus microgrid. The three bus microgrid system was used as a case study to highlight the design and optimization capability of a large-signal-based approach. The study explores the effect of system component sizing, load transient and generation variations on the asymptotic stability of the microgrid. Essentially, this advancement gives microgrid designers and engineers the ability to manipulate the domain of asymptotic stability depending on performance requirements. Especially important, this research was able to couple the domain of asymptotic stability of the ac microgrid with that of the dc side voltage source. Time domain simulations were used to demonstrate the mathematical nonlinear analysis results.

The Anderson localization problem, the Fermi-Pasta-Ulam paradox and the generalized diffusion approach

NASA Astrophysics Data System (ADS)

Kuzovkov, V. N.

2011-12-01

The goal of this paper is twofold. First, based on the interpretation of a quantum tight-binding model in terms of a classical Hamiltonian map, we consider the Anderson localization (AL) problem as the Fermi-Pasta-Ulam (FPU) effect in a modified dynamical system containing both stable and unstable (inverted) modes. Delocalized states in the AL are analogous to the stable quasi-periodic motion in FPU, whereas localized states are analogous to thermalization, respectively. The second aim is to use the classical Hamilton map for a simplified derivation of exact equations for the localization operator H(z). The latter was presented earlier (Kuzovkov et al 2002 J. Phys.: Condens. Matter 14 13777) treating the AL as a generalized diffusion in a dynamical system. We demonstrate that counter-intuitive results of our studies of the AL are similar to the FPU counter-intuitivity.

Experimental and Theoretical Results in Output-Trajectory Redesign for Flexible Structures

NASA Technical Reports Server (NTRS)

Dewey, J. S.; Devasia, Santosh

1996-01-01

In this paper we study the optimal redesign of output trajectory for linear invertible systems. This is particularly important for tracking control of flexible structures because the input-state trajectories that achieve the required output may cause excessive vibrations in the structure. A trade-off is then required between tracking and vibrations reduction. We pose and solve this problem as the minimization of a quadratic cost function. The theory is developed and applied to the output tracking of a flexible structure and experimental results are presented.

Growth of a Large-Area, Free-Standing, Highly Conductive and Fully Foldable Silver Film with Inverted Pyramids for Wearable Electronics Applications.

PubMed

Yu, Xiao; Li, Zihua; Liu, Yong; Zhao, Wenxia; Xu, Ruimei; Wang, Donghai; Shen, Hui

2017-02-15

A promising new concept is the application of flexible and foldable conductive film or paper for wearable electronics, in which silver nanowires, carbon nanotubes, and graphene are primarily used as conductive materials. However, their insufficient nanostructure contacts lead to poor electrical conductivity and mechanical fracture. Here, we demonstrate a simple and innovative strategy for fabricating a free-standing silver film with inverted pyramids by replicating pyramids on a textured silicon wafer under a hydrothermal reaction. In this unique structure, the inverted pyramids on the film surface can provide sufficient buffer space for a mechanically foldable and unfoldable cushion, and the continuous film ensures an uninterrupted electron transport pathway. As a result, the silver film with inverted pyramids can exhibit extremely high conductivity, with a sheet resistance as low as 2.55 × 10 -3 Ω/sq, corresponding to an electrical conductivity of 4.2 × 10 5 S cm -1 for a 9.2-μm-thick film (67.7% of bulk silver's conductivity). Surprisingly, this film has outstanding mechanical folding stability, with less than a 0.5% deviation from the initial resistance after 35,000 repetitive folding and unfolding cycles when tested at the folding site. The film is free-standing, thin, flexible, foldable, and suitable for cutting and patterned growth, which makes it suitable for wearable electronics, showing a much wider range of applications than substrate-based ones.

Homogeneous 2D MoTe2 p-n Junctions and CMOS Inverters formed by Atomic-Layer-Deposition-Induced Doping.

PubMed

Lim, June Yeong; Pezeshki, Atiye; Oh, Sehoon; Kim, Jin Sung; Lee, Young Tack; Yu, Sanghyuck; Hwang, Do Kyung; Lee, Gwan-Hyoung; Choi, Hyoung Joon; Im, Seongil

2017-08-01

Recently, α-MoTe 2 , a 2D transition-metal dichalcogenide (TMD), has shown outstanding properties, aiming at future electronic devices. Such TMD structures without surface dangling bonds make the 2D α-MoTe 2 a more favorable candidate than conventional 3D Si on the scale of a few nanometers. The bandgap of thin α-MoTe 2 appears close to that of Si and is quite smaller than those of other typical TMD semiconductors. Even though there have been a few attempts to control the charge-carrier polarity of MoTe 2 , functional devices such as p-n junction or complementary metal-oxide-semiconductor (CMOS) inverters have not been reported. Here, we demonstrate a 2D CMOS inverter and p-n junction diode in a single α-MoTe 2 nanosheet by a straightforward selective doping technique. In a single α-MoTe 2 flake, an initially p-doped channel is selectively converted to an n-doped region with high electron mobility of 18 cm 2 V -1 s -1 by atomic-layer-deposition-induced H-doping. The ultrathin CMOS inverter exhibits a high DC voltage gain of 29, an AC gain of 18 at 1 kHz, and a low static power consumption of a few nanowatts. The results show a great potential of α-MoTe 2 for future electronic devices based on 2D semiconducting materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transfer-printing of active layers to achieve high quality interfaces in sequentially deposited multilayer inverted polymer solar cells fabricated in air

PubMed Central

Vohra, Varun; Anzai, Takuya; Inaba, Shusei; Porzio, William; Barba, Luisa

2016-01-01

Abstract Polymer solar cells (PSCs) are greatly influenced by both the vertical concentration gradient in the active layer and the quality of the various interfaces. To achieve vertical concentration gradients in inverted PSCs, a sequential deposition approach is necessary. However, a direct approach to sequential deposition by spin-coating results in partial dissolution of the underlying layers which decreases the control over the process and results in not well-defined interfaces. Here, we demonstrate that by using a transfer-printing process based on polydimethylsiloxane (PDMS) stamps we can obtain increased control over the thickness of the various layers while at the same time increasing the quality of the interfaces and the overall concentration gradient within the active layer of PSCs prepared in air. To optimize the process and understand the influence of various interlayers, our approach is based on surface free energy, spreading parameters and work of adhesion calculations. The key parameter presented here is the insertion of high quality hole transporting and electron transporting layers, respectively above and underneath the active layer of the inverted structure PSC which not only facilitates the transfer process but also induces the adequate vertical concentration gradient in the device to facilitate charge extraction. The resulting non-encapsulated devices (active layer prepared in air) demonstrate over 40% increase in power conversion efficiency with respect to the reference spin-coated inverted PSCs. PMID:27877901

Distance descending ordering method: An O(n) algorithm for inverting the mass matrix in simulation of macromolecules with long branches

NASA Astrophysics Data System (ADS)

Xu, Xiankun; Li, Peiwen

2017-11-01

Fixman's work in 1974 and the follow-up studies have developed a method that can factorize the inverse of mass matrix into an arithmetic combination of three sparse matrices-one of them is positive definite and needs to be further factorized by using the Cholesky decomposition or similar methods. When the molecule subjected to study is of serial chain structure, this method can achieve O (n) time complexity. However, for molecules with long branches, Cholesky decomposition about the corresponding positive definite matrix will introduce massive fill-in due to its nonzero structure. Although there are several methods can be used to reduce the number of fill-in, none of them could strictly guarantee for zero fill-in for all molecules according to our test, and thus cannot obtain O (n) time complexity by using these traditional methods. In this paper we present a new method that can guarantee for no fill-in in doing the Cholesky decomposition, which was developed based on the correlations between the mass matrix and the geometrical structure of molecules. As a result, the inverting of mass matrix will remain the O (n) time complexity, no matter the molecule structure has long branches or not.

Transdimensional inversion of scattered body waves for 1D S-wave velocity structure - Application to the Tengchong volcanic area, Southwestern China

NASA Astrophysics Data System (ADS)

Li, Mengkui; Zhang, Shuangxi; Bodin, Thomas; Lin, Xu; Wu, Tengfei

2018-06-01

Inversion of receiver functions is commonly used to recover the S-wave velocity structure beneath seismic stations. Traditional approaches are based on deconvolved waveforms, where the horizontal component of P-wave seismograms is deconvolved by the vertical component. Deconvolution of noisy seismograms is a numerically unstable process that needs to be stabilized by regularization parameters. This biases noise statistics, making it difficult to estimate uncertainties in observed receiver functions for Bayesian inference. This study proposes a method to directly invert observed radial waveforms and to better account for data noise in a Bayesian formulation. We illustrate its feasibility with two synthetic tests having different types of noises added to seismograms. Then, a real site application is performed to obtain the 1-D S-wave velocity structure beneath a seismic station located in the Tengchong volcanic area, Southwestern China. Surface wave dispersion measurements spanning periods from 8 to 65 s are jointly inverted with P waveforms. The results show a complex S-wave velocity structure, as two low velocity zones are observed in the crust and uppermost mantle, suggesting the existence of magma chambers, or zones of partial melt. The upper magma chambers may be the heart source that cause the thermal activity on the surface.

Data Compression in Full-Text Retrieval Systems.

ERIC Educational Resources Information Center

Bell, Timothy C.; And Others

1993-01-01

Describes compression methods for components of full-text systems such as text databases on CD-ROM. Topics discussed include storage media; structures for full-text retrieval, including indexes, inverted files, and bitmaps; compression tools; memory requirements during retrieval; and ranking and information retrieval. (Contains 53 references.)…

New type of transformerless high efficiency inverter

NASA Astrophysics Data System (ADS)

Naaijer, G. J.

Inverter architectures are presented which allow economical ac/dc switching for solar cell array and battery power use in domestic and industrial applications. The efficiencies of currently available inverters are examined and compared with a new 2.2 kW transformerless stepped wave inverter. The inverter has low no-load losses, amounting to 200 Wh/24 hr, and features voltage steps occurring 15-30 times/sine wave period. An example is provided for an array/battery/inverter assembly with the inverter control electronics activating or disconnecting the battery subassemblies based on the total number of activated subassemblies in relation to a reference sinewave, and the need to average the battery subassembly discharge rates. A total harmonic distortion of 6 percent was observed, and the system is noted to be usable as a battery charger.

Harmonic Structure Predicts the Enjoyment of Uplifting Trance Music.

PubMed

Agres, Kat; Herremans, Dorien; Bigo, Louis; Conklin, Darrell

2016-01-01

An empirical investigation of how local harmonic structures (e.g., chord progressions) contribute to the experience and enjoyment of uplifting trance (UT) music is presented. The connection between rhythmic and percussive elements and resulting trance-like states has been highlighted by musicologists, but no research, to our knowledge, has explored whether repeated harmonic elements influence affective responses in listeners of trance music. Two alternative hypotheses are discussed, the first highlighting the direct relationship between repetition/complexity and enjoyment, and the second based on the theoretical inverted-U relationship described by the Wundt curve. We investigate the connection between harmonic structure and subjective enjoyment through interdisciplinary behavioral and computational methods: First we discuss an experiment in which listeners provided enjoyment ratings for computer-generated UT anthems with varying levels of harmonic repetition and complexity. The anthems were generated using a statistical model trained on a corpus of 100 uplifting trance anthems created for this purpose, and harmonic structure was constrained by imposing particular repetition structures (semiotic patterns defining the order of chords in the sequence) on a professional UT music production template. Second, the relationship between harmonic structure and enjoyment is further explored using two computational approaches, one based on average Information Content, and another that measures average tonal tension between chords. The results of the listening experiment indicate that harmonic repetition does in fact contribute to the enjoyment of uplifting trance music. More compelling evidence was found for the second hypothesis discussed above, however some maximally repetitive structures were also preferred. Both computational models provide evidence for a Wundt-type relationship between complexity and enjoyment. By systematically manipulating the structure of chord progressions, we have discovered specific harmonic contexts in which repetitive or complex structure contribute to the enjoyment of uplifting trance music.

Harmonic Structure Predicts the Enjoyment of Uplifting Trance Music

PubMed Central

Agres, Kat; Herremans, Dorien; Bigo, Louis; Conklin, Darrell

2017-01-01

An empirical investigation of how local harmonic structures (e.g., chord progressions) contribute to the experience and enjoyment of uplifting trance (UT) music is presented. The connection between rhythmic and percussive elements and resulting trance-like states has been highlighted by musicologists, but no research, to our knowledge, has explored whether repeated harmonic elements influence affective responses in listeners of trance music. Two alternative hypotheses are discussed, the first highlighting the direct relationship between repetition/complexity and enjoyment, and the second based on the theoretical inverted-U relationship described by the Wundt curve. We investigate the connection between harmonic structure and subjective enjoyment through interdisciplinary behavioral and computational methods: First we discuss an experiment in which listeners provided enjoyment ratings for computer-generated UT anthems with varying levels of harmonic repetition and complexity. The anthems were generated using a statistical model trained on a corpus of 100 uplifting trance anthems created for this purpose, and harmonic structure was constrained by imposing particular repetition structures (semiotic patterns defining the order of chords in the sequence) on a professional UT music production template. Second, the relationship between harmonic structure and enjoyment is further explored using two computational approaches, one based on average Information Content, and another that measures average tonal tension between chords. The results of the listening experiment indicate that harmonic repetition does in fact contribute to the enjoyment of uplifting trance music. More compelling evidence was found for the second hypothesis discussed above, however some maximally repetitive structures were also preferred. Both computational models provide evidence for a Wundt-type relationship between complexity and enjoyment. By systematically manipulating the structure of chord progressions, we have discovered specific harmonic contexts in which repetitive or complex structure contribute to the enjoyment of uplifting trance music. PMID:28119641

Inverter for Interchangeable Use as Current Source Inverter and Voltage Source Inverter for Interconnecting to Grid

NASA Astrophysics Data System (ADS)

Teruya, Daisuke; Masukawa, Shigeo; Iida, Shoji

We propose a novel inverter that can be operated either as a Current Source Inverter (CSI) or as a Voltage Source Inverter (VSI) by changing only the control signals. It is proper to apply it to the interconnecting system with renewal energy, such as photovoltaic cells or wind generation systems, to a grid. This inverter is usually operated as the CSI connected to the grid. Even if the energy source has a lower voltage than the grid, the energy can be supplied to the grid through the proposed inverter. The power factor can be briefly maintained at almost unity. When power supply from the grid is interrupted, the proposed circuit should be operated as the VSI in the stand-alone operation mode. In this way, the circuit can maintain a constant output voltage to the loads. In this paper, the proposed circuit configuration and the control schemes for both the CSI and the VSI are described. Further, the circuit characteristics for both are discussed experimentally.

Integration of supercapacitive storage in renewable energy system to compare the response of two level and five level inverter with RL type load

NASA Astrophysics Data System (ADS)

Jana, Suman; Biswas, Pabitra Kumar; Das, Upama

2018-04-01

The analytical and simulation-based study in this presented paper shows a comparative report between two level inverter and five-level inverter with the integration of Supercapacitive storage in Renewable Energy system. Sometime dependent numerical models are used to measure the voltage and current response of two level and five level inverter in MATLAB Simulink based environment. In this study supercapacitive sources, which are fed by solar cells are used as input sources to experiment the response of multilevel inverter with integration of su-percapacitor as a storage device of Renewable Energy System. The RL load is used to compute the time response in MATLABSimulink based environment. With the simulation results a comparative study has been made of two different level types of inverters. Two basic types of inverter are discussed in the study with reference to their electrical behavior. It is also simulated that multilevel inverter can convert stored energy within supercapacitor which is extracted from Renewable Energy System.

Chapter 11.2: Inverters, Power Optimizers, and Microinverters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deline, Christopher A

Inverters span a wide range of sizes, topologies, and connection voltages: from utility-scale megawatt inverters to string inverters. Switch-mode power conversion relies on high frequency chopping of DC signal to periodically charge and discharge energy storage elements, such as inductors and capacitors. Additional circuit components are required to address practical issues in inverters such as voltage ripple and harmonic distortion. Inverters are beginning to incorporate components with a bandgap above should be 3 eV, such as SiC and GaN. Photovoltaic (PV) modules respond dynamically to changing temperature and irradiation conditions. Thus, maximum DC power extraction requires periodic adjustment of themore » PV voltage and current operating point. An inverter's total efficiency is measured by the product of its conversion efficiency and the maximum-power-point tracking (MPPT) efficiency. This chapter lists the primary functions of inverters that include auxiliary capabilities, such as monitoring of DC and AC performance, and other error reporting.« less

Eikonal Tomography of the Southern California Plate Boundary Region

NASA Astrophysics Data System (ADS)

Qiu, H.; Ben-Zion, Y.; Zigone, D.; Lin, F. C.

2016-12-01

We use eikonal tomography to derive directionally-dependent phase velocities of surface waves for the plate boundary region in southern CA sensitive to the approximate depth range 1-20 km. Seismic noise data recorded by 346 stations in the area provide a spatial coverage with 5-25 km typical station spacing and period range of 1-20 s. Noise cross-correlations are calculated for vertical component data recorded in year 2014. Rayleigh wave group and phase travel times between 2 and 13 sec period are derived for each station pair using frequency-time analysis. For each common station, all available phase travel time measurements with sufficient signal to noise ratio and envelope peak amplitude are used to construct a travel time map for a virtual source at the common station location. By solving the eikonal equation, both phase velocity and propagation direction are evaluated at each location for each virtual source. Isotropic phase velocities and 2-psi azimuthal anisotropy and their uncertainties are determined statistically using measurements from different virtual sources. Following the method of Barmin et al. (2001), group velocities are also inverted using all the group travel times that pass quality criteria. The obtained group and phase dispersions of Rayleigh waves are then inverted on a 6 x 6 km2 grid for local 1D piecewise shear wave velocity structures using the procedure of Herrmann (2013). The results agree well with previous observations of Zigone et al. (2015) in the overlapping area. Clear velocity contrasts and low velocity zones are seen for the San Andreas, San Jacinto, Elsinore and Garlock faults. We also find 2-psi azimuthal anisotropy with fast directions parallel to geometrically-simple fault sections. Details and updated results will be presented in the meeting.

Investigation of inversion polymorphisms in the human genome using principal components analysis.

PubMed

Ma, Jianzhong; Amos, Christopher I

2012-01-01

Despite the significant advances made over the last few years in mapping inversions with the advent of paired-end sequencing approaches, our understanding of the prevalence and spectrum of inversions in the human genome has lagged behind other types of structural variants, mainly due to the lack of a cost-efficient method applicable to large-scale samples. We propose a novel method based on principal components analysis (PCA) to characterize inversion polymorphisms using high-density SNP genotype data. Our method applies to non-recurrent inversions for which recombination between the inverted and non-inverted segments in inversion heterozygotes is suppressed due to the loss of unbalanced gametes. Inside such an inversion region, an effect similar to population substructure is thus created: two distinct "populations" of inversion homozygotes of different orientations and their 1:1 admixture, namely the inversion heterozygotes. This kind of substructure can be readily detected by performing PCA locally in the inversion regions. Using simulations, we demonstrated that the proposed method can be used to detect and genotype inversion polymorphisms using unphased genotype data. We applied our method to the phase III HapMap data and inferred the inversion genotypes of known inversion polymorphisms at 8p23.1 and 17q21.31. These inversion genotypes were validated by comparing with literature results and by checking Mendelian consistency using the family data whenever available. Based on the PCA-approach, we also performed a preliminary genome-wide scan for inversions using the HapMap data, which resulted in 2040 candidate inversions, 169 of which overlapped with previously reported inversions. Our method can be readily applied to the abundant SNP data, and is expected to play an important role in developing human genome maps of inversions and exploring associations between inversions and susceptibility of diseases.

Joint inversion of seismic and gravity data for imaging seismic velocity structure of the crust and upper mantle beneath Utah, United States

NASA Astrophysics Data System (ADS)

Syracuse, E. M.; Zhang, H.; Maceira, M.

2017-10-01

We present a method for using any combination of body wave arrival time measurements, surface wave dispersion observations, and gravity data to simultaneously invert for three-dimensional P- and S-wave velocity models. The simultaneous use of disparate data types takes advantage of the differing sensitivities of each data type, resulting in a comprehensive and higher resolution three-dimensional geophysical model. In a case study for Utah, we combine body wave first arrivals mainly from the USArray Transportable Array, Rayleigh wave group and phase velocity dispersion data, and Bouguer gravity anomalies to invert for crustal and upper mantle structure of the region. Results show clear delineations, visible in both P- and S-wave velocities, between the three main tectonic provinces in the region. Without the inclusion of the surface wave and gravity constraints, these delineations are less clear, particularly for S-wave velocities. Indeed, checkerboard tests confirm that the inclusion of the additional datasets dramatically improves S-wave velocity recovery, with more subtle improvements to P-wave velocity recovery, demonstrating the strength of the method in successfully recovering seismic velocity structure from multiple types of constraints.

Full waveform inversion of combined towed streamer and limited OBS seismic data: a theoretical study

NASA Astrophysics Data System (ADS)

Yang, Huachen; Zhang, Jianzhong

2018-06-01

In marine seismic oil exploration, full waveform inversion (FWI) of towed-streamer data is used to reconstruct velocity models. However, the FWI of towed-streamer data easily converges to a local minimum solution due to the lack of low-frequency content. In this paper, we propose a new FWI technique using towed-streamer data, its integrated data sets and limited OBS data. Both integrated towed-streamer seismic data and OBS data have low-frequency components. Therefore, at early iterations in the new FWI technique, the OBS data combined with the integrated towed-streamer data sets reconstruct an appropriate background model. And the towed-streamer seismic data play a major role in later iterations to improve the resolution of the model. The new FWI technique is tested on numerical examples. The results show that when starting models are not accurate enough, the models inverted using the new FWI technique are superior to those inverted using conventional FWI.

A leftward bias however you look at it: Revisiting the emotional chimeric face task as a tool for measuring emotion lateralization.

PubMed

R Innes, Bobby; Burt, D Michael; Birch, Yan K; Hausmann, Markus

2015-12-28

Left hemiface biases observed within the Emotional Chimeric Face Task (ECFT) support emotional face perception models whereby all expressions are preferentially processed by the right hemisphere. However, previous research using this task has not considered that the visible midline between hemifaces might engage atypical facial emotion processing strategies in upright or inverted conditions, nor controlled for left visual field (thus right hemispheric) visuospatial attention biases. This study used novel emotional chimeric faces (blended at the midline) to examine laterality biases for all basic emotions. Left hemiface biases were demonstrated across all emotional expressions and were reduced, but not reversed, for inverted faces. The ECFT bias in upright faces was significantly increased in participants with a large attention bias. These results support the theory that left hemiface biases reflect a genuine bias in emotional face processing, and this bias can interact with attention processes similarly localized in the right hemisphere.

Electron Doping of Ultrathin Black Phosphorus with Cu Adatoms.

PubMed

Koenig, Steven P; Doganov, Rostislav A; Seixas, Leandro; Carvalho, Alexandra; Tan, Jun You; Watanabe, Kenji; Taniguchi, Takashi; Yakovlev, Nikolai; Castro Neto, Antonio H; Özyilmaz, Barbaros

2016-04-13

Few-layer black phosphorus is a monatomic two-dimensional crystal with a direct band gap that has high carrier mobility for both holes and electrons. Similarly to other layered atomic crystals, like graphene or layered transition metal dichalcogenides, the transport behavior of few-layer black phosphorus is sensitive to surface impurities, adsorbates, and adatoms. Here we study the effect of Cu adatoms onto few-layer black phosphorus by characterizing few-layer black phosphorus field effect devices and by performing first-principles calculations. We find that the addition of Cu adatoms can be used to controllably n-dope few layer black phosphorus, thereby lowering the threshold voltage for n-type conduction without degrading the transport properties. We demonstrate a scalable 2D material-based complementary inverter which utilizes a boron nitride gate dielectric, a graphite gate, and a single bP crystal for both the p- and n-channels. The inverter operates at matched input and output voltages, exhibits a gain of 46, and does not require different contact metals or local electrostatic gating.

A study on the impact of high penetration distributed generation inverters on grid operation and stability

NASA Astrophysics Data System (ADS)

Gu, Fei; Brouwer, Jack; Samuelsen, Scott

2013-09-01

Recent advances in inverter technology have enabled ancillary services such as volt/VAR regulation, SCADA communications, and active power filtering. Smart inverters can not only provide real power, but can be controlled to use excess capacity to provide reactive power compensation, power flow control, and active power filtering without supplementary inverter hardware. A transient level inverter model based on the Solectria 7700 inverter is developed and used to assess these control strategies using field data from an existing branch circuit containing two Amonix 68kW CPV-7700 systems installed at the University of California, Irvine.

Nonlinear analysis of a family of LC tuned inverters. [dc to square wave circuits for power conditioning

NASA Technical Reports Server (NTRS)

Lee, F. C. Y.; Wilson, T. G.

1974-01-01

A family of four dc-to-square-wave LC tuned inverters are analyzed using singular point. Limit cycles and waveshape characteristics are given for three modes of oscillation: quasi-harmonic, relaxation, and discontinuous. An inverter in which the avalanche breakdown of the transistor emitter-to-base junction occurs is discussed and the starting characteristics of this family of inverters are presented. The LC tuned inverters are shown to belong to a family of inverters with a common equivalent circuit consisting of only three 'series' elements: a five-segment piecewise-linear current-controlled resistor, linear inductor, and linear capacitor.

DC-DC Type High-Frequency Link DC for Improved Power Quality of Cascaded Multilevel Inverter

NASA Astrophysics Data System (ADS)

Sadikin, Muhammad; Senjyu, Tomonobu; Yona, Atsushi

2013-06-01

Multilevel inverters are emerging as a new breed of power converter options for power system applications. Recent advances in power switching devices enabled the suitability of multilevel inverters for high voltage and high power applications because they are connecting several devices in series without the need of component matching. Usually, a transformerless battery energy storage system, based on a cascaded multilevel inverter, is used as a measure for voltage and frequency deviations. System can be reduced in size, weight, and cost of energy storage system. High-frequency link circuit topology is advantageous in realizing compact and light-weight power converters for uninterruptible power supply systems, new energy systems using photovoltaic-cells, fuel-cells and so on. This paper presents a DC-DC type high-frequency link DC (HFLDC) cascaded multilevel inverter. Each converter cell is implemented a control strategy for two H-bridge inverters that are controlled with the same multicarrier pulse width modulation (PWM) technique. The proposed cascaded multilevel inverter generates lower voltage total harmonic distortion (THD) in comparison with conventional cascaded multilevel inverter. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of the proposed cascaded multilevel inverter.

A Single-Phase Embedded Z-Source DC-AC Inverter

PubMed Central

Kim, Se-Jin; Lim, Young-Cheol

2014-01-01

In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively. PMID:25133241

A single-phase embedded Z-source DC-AC inverter.

PubMed

Kim, Se-Jin; Lim, Young-Cheol

2014-01-01

In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

Late tectonic uplift of an inverted oceanic basin in South East Asia: the case of Palawan Island (western Philippines)

NASA Astrophysics Data System (ADS)

Meresse, F.; Savva, D.; Pubellier, M.; Steuer, S.; Franke, D.; Cordey, F.; Muller, C.; Sapin, F.; Mouly, B.; Auxiètre, J.-L.

2012-04-01

The elongated island of Palawan, bounded by two marginal basins, the South China Sea to the North and the Sulu Sea to the South is composed of remnants of an inverted basin (Proto-South China Sea) thrusted onto the margin of a continental terrane which rifted away from the Chinese-Vietnamese margin. Based on field observations coupled with seismic and drill-holes data, our study focuses on the structural architecture of the island in order to decipher the geodynamic evolution of the southern margin of the South China Sea. Structurally, the Palawan Island consists of: (i) the Palawan wedge, which extends towards the South China Sea is composed of deformed slope to deep ocean deposits of Cretaceous (north Palawan) to Tertiary (central and south Palawan) ages. This accretionnary wedge is characterized by small wavelength folds of mainly NE-SW trend. Offshore, the unconformable Middle-Late Miocene Tabon limestones unit postdates the last stages of the Palawan wedge growth/setting; (ii) On top of this wedge lie thrust slices of ophiolite bodies comprising ribbon cherts of Albian age as indicated by radiolarians.; these bodies are likely to be relicts of the now-subducted Proto South China Sea; (iii) The central and southern parts of the Palawan island are characterized by a large wavelength antiform of NE-SW trend. This structure is sealed by the slightly tilted Early Pliocene marls unit; (iv) The island also presents necking zones bordered by N-S trending transform faults. This area witnessed the geodynamic evolution of the South East Asia which consists of a succession of opening/closure of oceanic basins and block accretions. The Palawan Island therefore results of the closing of the Proto-South China Sea which once formed both the Palawan accretionary wedge and the overlying ophiolite tectonic slices. During a later compressive event, the rifted continental margin which composes the basement of the Island was inverted, inducing the uplift and the large scale folding of the Palawan Island. In a final stage, the strain relaxing results in the formation of the necking zones, probably reactivating the inherited transform faults of the Proto-South China Sea. Keywords: Palawan Island; South China Sea; oceanic basin; inverted margin; Ophiolite.

Construction and evaluation of photovoltaic power generation and power storage system using SiC field-effect transistor inverter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Matsumoto, Taisuke; Ohishi, Yuya

A power storage system using spherical silicon (Si) solar cells, maximum power point tracking charge controller, lithium-ion battery and a direct current-alternating current (DC-AC) inverter was constructed. Performance evaluation of the DC-AC inverter was carried out, and the DC-AC conversion efficiencies of the SiC field-effect transistor (FET) inverter was improved compared with those of the ordinary Si-FET based inverter.

Telomerase reverse transcriptase (TERT) promoter mutation analysis of benign, malignant and reactive urothelial lesions reveals a subpopulation of inverted papilloma with immortalizing genetic change.

PubMed

Cheng, Liang; Davidson, Darrell D; Wang, Mingsheng; Lopez-Beltran, Antonio; Montironi, Rodolfo; Wang, Lisha; Tan, Puay-Hoon; MacLennan, Gregory T; Williamson, Sean R; Zhang, Shaobo

2016-07-01

To understand more clearly the genetic ontogeny of inverted papilloma of urinary bladder, we analysed telomerase reverse transcriptase (TERT) promoter mutation status in a group of 26 inverted papillomas in comparison with the mutation status of urothelial carcinoma with inverted growth (26 cases), conventional urothelial carcinoma (36 Ta non-invasive urothelial carcinoma, 35 T2 invasive urothelial carcinoma) and cystitis glandularis (25 cases). TERT promoter mutations in inverted papilloma, urothelial carcinoma with inverted growth, urothelial carcinoma and cystitis glandularis were found in 15% (four of 26), 58% (15 of 26), 63% (45 of 71) and 0% (none of 25), respectively. C228T mutations were the predominant mutations (97%) found in bladder tumours, while C250T aberrations occurred in approximately 3% of bladder tumours. In the inverted papilloma group, TERT mutation occurred predominantly in female patients (P = 0.006). Among urothelial carcinomas, TERT promoter mutation status did not correlate with gender, histological grade or pathological stage. TERT promoter mutations were found in 15% of inverted papillomas. Our data suggest that there is a subpopulation of inverted papilloma that shares a carcinogenetic pathway with urothelial carcinoma with inverted growth and conventional urothelial carcinomas. Caution is warranted in exploring TERT promoter mutation status as a screening or adjunct diagnostic test for bladder cancer. © 2015 John Wiley & Sons Ltd.

Accessing the uncertainties of seismic velocity and anisotropy structure of Northern Great Plains using a transdimensional Bayesian approach

NASA Astrophysics Data System (ADS)

Gao, C.; Lekic, V.

2017-12-01

Seismic imaging utilizing complementary seismic data provides unique insight on the formation, evolution and current structure of continental lithosphere. While numerous efforts have improved the resolution of seismic structure, the quantification of uncertainties remains challenging due to the non-linearity and the non-uniqueness of geophysical inverse problem. In this project, we use a reverse jump Markov chain Monte Carlo (rjMcMC) algorithm to incorporate seismic observables including Rayleigh and Love wave dispersion, Ps and Sp receiver function to invert for shear velocity (Vs), compressional velocity (Vp), density, and radial anisotropy of the lithospheric structure. The Bayesian nature and the transdimensionality of this approach allow the quantification of the model parameter uncertainties while keeping the models parsimonious. Both synthetic test and inversion of actual data for Ps and Sp receiver functions are performed. We quantify the information gained in different inversions by calculating the Kullback-Leibler divergence. Furthermore, we explore the ability of Rayleigh and Love wave dispersion data to constrain radial anisotropy. We show that when multiple types of model parameters (Vsv, Vsh, and Vp) are inverted simultaneously, the constraints on radial anisotropy are limited by relatively large data uncertainties and trade-off strongly with Vp. We then perform joint inversion of the surface wave dispersion (SWD) and Ps, Sp receiver functions, and show that the constraints on both isotropic Vs and radial anisotropy are significantly improved. To achieve faster convergence of the rjMcMC, we propose a progressive inclusion scheme, and invert SWD measurements and receiver functions from about 400 USArray stations in the Northern Great Plains. We start by only using SWD data due to its fast convergence rate. We then use the average of the ensemble as a starting model for the joint inversion, which is able to resolve distinct seismic signatures of geological structures including the trans-Hudson orogen, Wyoming craton and Yellowstone hotspot. Various analyses are done to access the uncertainties of the seismic velocities and Moho depths. We also address the importance of careful data processing of receiver functions by illustrating artifacts due to unmodelled sediment reverberations.

Improved reservoir characterisation using fuzzy logic platform: an integrated petrophysical, seismic structural and poststack inversion study

NASA Astrophysics Data System (ADS)

Jafri, Muhammad Kamran; Lashin, Aref; Ibrahim, El-Khedr Hassan; Hassanein, Kamal A.; Al Arifi, Nassir; Naeem, Muhammad

2017-06-01

There is a tendency for applying different integrated geophysical approaches for better hydrocarbon reservoir characterisation and interpretation. In this study, petrophysical properties, seismic structural and poststack seismic inversion results are integrated using the fuzzy logic AND operator to characterise the Tensleep Sandstone Formation (TSF) at Powder River Basin (PRB), Wyoming, USA. TSF is deposited in a coastal plain setting during the Pennsylvanian era, and contains cross-bedded sandstone of Aeolian origin as a major lithology with alternative sabkha dolomite/carbonates. Wireline logging datasets from 17 wells are used for the detailed petrophysical evaluation. Three units of the TSF (A-sandstone, B-dolomite and B-sandstone) are targeted and their major rock properties estimated (i.e. shale/clay volume, Vsh; porosity, φEff permeability, K; fluid saturations, Sw and SH; and bulk volume water, BVW). The B-sandstone zone, with its petrophysical properties of 5-20% effective porosity, 0.10-250 mD permeability and hydrocarbon potential up to 72%, is considered the best reservoir zone among the three studied units. Distributions of the most important petrophysical parameters of the B-sandstone reservoir (Vsh, φEff, K, Sw) are generated as GIS thematic layers. The two-dimensional (2D) and three-dimensional (3D) seismic structural interpretations revealed that the hydrocarbons are entrapped in an anticlinal structure bounded with fault closures at the west of the study area. Poststack acoustic impedance (PSAI) inversion is performed on 3D seismic data to extract the inverted acoustic impedance (AI) cube. Two attribute slices (inverted AI and seismic amplitude) were extracted at the top of the B-sandstone unit as GIS thematic layers. The reservoir properties and inverted seismic attributes were then integrated using fuzzy AND operator. Finally, a fuzzy reservoir quality map was produced, and a prospective reservoir area with best reservoir characteristics is proposed for future exploration. The current study showed that integration of petrophysical, seismic structural and poststack inversion under a fuzzy logic platform can be used as an effective tool for interpreting multiple reservoir zones.

Etiological role of human papillomavirus infection for inverted papilloma of the bladder.

PubMed

Shigehara, Kazuyoshi; Sasagawa, Toshiyuki; Doorbar, John; Kawaguchi, Shohei; Kobori, Yoshitomo; Nakashima, Takao; Shimamura, Masayoshi; Maeda, Yuji; Miyagi, Tohru; Kitagawa, Yasuhide; Kadono, Yoshifumi; Konaka, Hiroyuki; Mizokami, Atsushi; Koh, Eitetsu; Namiki, Mikio

2011-02-01

The status of human papillomavirus (HPV) infection in urothelial inverted papilloma was examined in the present study. Formalin-fixed and paraffin-embedded tissues from eight cases of inverted papilloma of the bladder were studied. The presence of HPV-DNA was examined by modified GP5/6+PCR using archival tissue sections by microdissection. HPV genotype was determined with a Hybri-Max HPV genotyping kit. Immunohistochemical analysis for p16-INK4a, mcm7, HPV-E4, and L1, and in situ hybridization for the HPV genome were performed. HPV was detected in seven of eight cases (87.5%) of inverted papilloma. Three cases were diagnosed as inverted papilloma with atypia, while the remaining five were typical cases. HPV-18 was detected in two cases, including one inverted papilloma with atypia, and HPV-16 was detected in four cases, including one inverted papilloma with atypia. Multiple HPV type infection was detected in one typical case and one atypical case. High-risk HPV was present in all HPV-positive cases. Cellular proteins, p16-INK4a and mcm7, which are surrogate markers for HPV-E7 expression, were detected in all HPV-positive cases, and their levels were higher in inverted papilloma with atypia than in typical cases. In contrast, HPV-E4 and L1, which are markers for HPV propagation, were observed in some parts of the typical inverted papilloma tissue. High-risk HPV infection may be one of the causes of urothelial inverted papilloma, and inverted papilloma with atypia may have malignant potential. 2010 Wiley-Liss, Inc.

Crustal Structure of Mars from Mars Global Surveyor Topography and Gravity

NASA Technical Reports Server (NTRS)

Zuber, M. T.; Solomon, S. C.; Phillips, R. J.; Smith, D. E.; Tyler, G. L.; Aharonson, O.; Balmino, G.; Banerdt, W. B.; Head, J. W.; Johnson, C. L.

2000-01-01

In this analysis we invert global models of Mars' topography from Mars Orbiter Laser Altimeter (MOLA) and gravity from Doppler tracking obtained during the mapping mission of Mars Global Surveyor (MGS). We analyze the distribution of Martian crust and discuss implications for Mars' thermal history.

The rolling-circle melting-pot model for porcine circovirus DNA replication

USDA-ARS?s Scientific Manuscript database

A stem-loop structure, formed by a pair of inverted repeats during DNA replication, is a conserved feature at the origin of DNA replication (Ori) among plant and animal viruses, bacteriophages and plasmids that replicate their genomes via the rolling-circle replication (RCR) mechanism. Porcine circo...

Improved Performance via the Inverted Classroom

ERIC Educational Resources Information Center

Weinstein, Randy D.

2015-01-01

This study examined student performance in an inverted thermodynamics course (lectures provided by video outside of class) compared to a traditional lecture class. Students in the inverted class performed better on their exams. Students in the bottom third of the inverted course showed the greatest improvement. These bottom third students had a C…

Inverting the Linear Algebra Classroom

ERIC Educational Resources Information Center

Talbert, Robert

2014-01-01

The inverted classroom is a course design model in which students' initial contact with new information takes place outside of class meetings, and students spend class time on high-level sense-making activities. The inverted classroom model is so called because it inverts or "flips" the usual classroom design where typically class…

Efficient/reliable dc-to-dc inverter circuit

NASA Technical Reports Server (NTRS)

Pasciutti, E. R.

1970-01-01

Feedback loop, which contains an inductor in series with a saturable reactor, is added to a standard inverter circuit to permit the inverter power transistors to be switched in a controlled and efficient manner. This inverter is applicable where the power source has either high or low impedance properties.

75 FR 36119 - In the Matter of Certain Cold Cathode Fluorescent Lamp (“CCFL”) Inverter Circuits and Products...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-24

... Cathode Fluorescent Lamp (``CCFL'') Inverter Circuits and Products Containing the Same; Notice of... States after importation of certain cold cathode fluorescent lamp inverter circuits and products..., and the sale within the United States after importation of CCFL inverter circuits and products...

Perception of biomechanical motions by infants: implementation of various processing constraints.

PubMed

Bertenthal, B I; Proffitt, D R; Kramer, S J

1987-11-01

Geometry informs us that there exist a large number of possible connectivity patterns consistent with a point-light display of a person walking. Yet there is only one pattern consistent with a "stick figure" representation of the human form, and that pattern is uniquely specified by those pairwise connections that remain locally rigid. In this study, sensitivity to local rigidity in biomechanical displays was investigated in 3- and 5-month-old infants. The results of Experiment 1 revealed that by 5 months of age, infants discriminate a locally rigid point-light walker display from one in which local rigidity is perturbed. In Experiment 2 we tested infants' sensitivity to the same stimuli when those stimuli were inverted. Contrary to the preceding experiment, the results revealed no evidence of discrimination. Taken together, these findings suggest that infants are sensitive to local rigidity in biomechanical displays but that this sensitivity is orientation specific. Possible mechanisms for this specificity are discussed in the context of additional constraints on the processing of biomechanical displays.

Experimental Evaluation of PV Inverter Anti-Islanding with Grid Support Functions in Multi-Inverter Island Scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoke, Anderson; Nelson, Austin; Miller, Brian

As PV and other DER systems are connected to the grid at increased penetration levels, island detection may become more challenging for two reasons: 1.) In islands containing many DERs, active inverter-based anti-islanding methods may have more difficulty detecting islands because each individual inverter's efforts to detect the island may be interfered with by the other inverters in the island. 2.) The increasing numbers of DERs are leading to new requirements that DERs ride through grid disturbances and even actively try to regulate grid voltage and frequency back towards nominal operating conditions. These new grid support requirements may directly ormore » indirectly interfere with anti-islanding controls. This report describes a series of tests designed to examine the impacts of both grid support functions and multi-inverter islands on anti-islanding effectiveness. Crucially, the multi-inverter anti-islanding tests described in this report examine scenarios with multiple inverters connected to multiple different points on the grid. While this so-called 'solar subdivision' scenario has been examined to some extent through simulation, this is the first known work to test it using hardware inverters. This was accomplished through the use of power hardware-in-the-loop (PHIL) simulation, which allows the hardware inverters to be connected to a real-time transient simulation of an electric power system that can be easily reconfigured to test various distribution circuit scenarios. The anti-islanding test design was a modified version of the unintentional islanding test in IEEE Standard 1547.1, which creates a balanced, resonant island with the intent of creating a highly challenging condition for island detection. Three common, commercially available single-phase PV inverters from three different manufacturers were tested. The first part of this work examined each inverter individually using a series of pure hardware resistive-inductive-capacitive (RLC) resonant load based anti-islanding tests to determine the worst-case configuration of grid support functions for each inverter. A grid support function is a function an inverter performs to help stabilize the grid or drive the grid back towards its nominal operating point. The four grid support functions examined here were voltage ride-through, frequency ride-through, Volt-VAr control, and frequency-Watt control. The worst-case grid support configuration was defined as the configuration that led to the maximum island duration (or run-on time, ROT) out of 50 tests of each inverter. For each of the three inverters, it was observed that maximum ROT increased when voltage and frequency ride-through were activated. No conclusive evidence was found that Volt-VAr control or frequency-Watt control increased maximum ROT. Over all single-inverter test cases, the maximum ROT was 711 ms, well below the two-second limit currently imposed by IEEE Standard 1547-2003. A subsequent series of 244 experiments tested all three inverters simultaneously in the same island. These tests again used a procedure based on the IEEE 1547.1 unintentional islanding test to create a difficult-to-detect island condition. For these tests, which used the two worst-case grid support function configurations from the single-inverter tests, the inverters were connected to a variety of island circuit topologies designed to represent the variety of multiple-inverter islands that may occur on real distribution circuits. The interconnecting circuits and the resonant island load itself were represented in the real-time PHIL model. PHIL techniques similar to those employed here have been previously used and validated for anti-islanding tests, and the PHIL resonant load model used in this test was successfully validated by comparing single-inverter PHIL tests to conventional tests using an RLC load bank.« less

A palindrome-mediated mechanism distinguishes translocations involving LCR-B of chromosome 22q11.2.

PubMed

Gotter, Anthony L; Shaikh, Tamim H; Budarf, Marcia L; Rhodes, C Harker; Emanuel, Beverly S

2004-01-01

Two known recurrent constitutional translocations, t(11;22) and t(17;22), as well as a non-recurrent t(4;22), display derivative chromosomes that have joined to a common site within the low copy repeat B (LCR-B) region of 22q11.2. This breakpoint is located between two AT-rich inverted repeats that form a nearly perfect palindrome. Breakpoints within the 11q23, 17q11 and 4q35 partner chromosomes also fall near the center of palindromic sequences. In the present work the breakpoints of a fourth translocation involving LCR-B, a balanced ependymoma-associated t(1;22), were characterized not only to localize this junction relative to known genes, but also to further understand the mechanism underlying these rearrangements. FISH mapping was used to localize the 22q11.2 breakpoint to LCR-B and the 1p21 breakpoint to single BAC clones. STS mapping narrowed the 1p21.2 breakpoint to a 1990 bp AT-rich region, and junction fragments were amplified by nested PCR. Junction fragment-derived sequence indicates that the 1p21.2 breakpoint splits a 278 nt palindrome capable of forming stem-loop secondary structure. In contrast, the 1p21.2 reference genomic sequence from clones in the database does not exhibit this configuration, suggesting a predisposition for regional genomic instability perhaps etiologic for this rearrangement. Given its similarity to known chromosomal fragile site (FRA) sequences, this polymorphic 1p21.2 sequence may represent one of the FRA1 loci. Comparative analysis of the secondary structure of sequences surrounding translocation breakpoints that involve LCR-B with those not involving this region indicate a unique ability of the former to form stem-loop structures. The relative likelihood of forming these configurations appears to be related to the rate of translocation occurrence. Further analysis suggests that constitutional translocations in general occur between sequences of similar melting temperature and propensity for secondary structure.

A palindrome-mediated mechanism distinguishes translocations involving LCR-B of chromosome 22q11.2

PubMed Central

Gotter, Anthony L.; Shaikh, Tamim H.; Budarf, Marcia L.; Rhodes, C. Harker; Emanuel, Beverly S.

2010-01-01

Two known recurrent constitutional translocations, t(11;22) and t(17;22), as well as a non-recurrent t(4;22), display derivative chromosomes that have joined to a common site within the low copy repeat B (LCR-B) region of 22q11.2. This breakpoint is located between two AT-rich inverted repeats that form a nearly perfect palindrome. Breakpoints within the 11q23, 17q11 and 4q35 partner chromosomes also fall near the center of palindromic sequences. In the present work the breakpoints of a fourth translocation involving LCR-B, a balanced ependymoma-associated t(1;22), were characterized not only to localize this junction relative to known genes, but also to further understand the mechanism underlying these rearrangements. FISH mapping was used to localize the 22q11.2 breakpoint to LCR-B and the 1p21 breakpoint to single BAC clones. STS mapping narrowed the 1p21.2 breakpoint to a 1990 bp AT-rich region, and junction fragments were amplified by nested PCR. Junction fragment-derived sequence indicates that the 1p21.2 breakpoint splits a 278 nt palindrome capable of forming stem–loop secondary structure. In contrast, the 1p21.2 reference genomic sequence from clones in the database does not exhibit this configuration, suggesting a predisposition for regional genomic instability perhaps etiologic for this rearrangement. Given its similarity to known chromosomal fragile site (FRA) sequences, this polymorphic 1p21.2 sequence may represent one of the FRA1 loci. Comparative analysis of the secondary structure of sequences surrounding translocation breakpoints that involve LCR-B with those not involving this region indicate a unique ability of the former to form stem–loop structures. The relative likelihood of forming these configurations appears to be related to the rate of translocation occurrence. Further analysis suggests that constitutional translocations in general occur between sequences of similar melting temperature and propensity for secondary structure. PMID:14613967

Inverter communications using output signal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, Patrick L.

Technologies for communicating information from an inverter configured for the conversion of direct current (DC) power generated from an alternative source to alternating current (AC) power are disclosed. The technologies include determining information to be transmitted from the inverter over a power line cable connected to the inverter and controlling the operation of an output converter of the inverter as a function of the information to be transmitted to cause the output converter to generate an output waveform having the information modulated thereon.

Stabilization and tracking control of X-Z inverted pendulum with sliding-mode control.

PubMed

Wang, Jia-Jun

2012-11-01

X-Z inverted pendulum is a new kind of inverted pendulum which can move with the combination of the vertical and horizontal forces. Through a new transformation, the X-Z inverted pendulum is decomposed into three simple models. Based on the simple models, sliding-mode control is applied to stabilization and tracking control of the inverted pendulum. The performance of the sliding mode control is compared with that of the PID control. Simulation results show that the design scheme of sliding-mode control is effective for the stabilization and tracking control of the X-Z inverted pendulum. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Model Predictive Control of LCL Three-level Photovoltaic Grid-connected Inverter

NASA Astrophysics Data System (ADS)

Liang, Cheng; Tian, Engang; Pang, Baobing; Li, Juan; Yang, Yang

2018-05-01

In this paper, neutral point clamped three-level inverter circuit is analyzed to establish a mathematical model of the three-level inverter in the αβ coordinate system. The causes and harms of the midpoint potential imbalance problem are described. The paper use the method of model predictive control to control the entire inverter circuit[1]. The simulation model of the inverter system is built in Matlab/Simulink software. It is convenient to control the grid-connected current, suppress the unbalance of the midpoint potential and reduce the switching frequency by changing the weight coefficient in the cost function. The superiority of the model predictive control in the control method of the inverter system is verified.