Cascading pressure reactor and method for solar-thermochemical reactions

DOEpatents

Ermanoski, Ivan

2017-11-14

Reactors and methods for solar thermochemical reactions are disclosed. The reactors and methods include a cascade of reduction chambers at successively lower pressures that leads to over an order of magnitude pressure decrease compared to a single-chambered design. The resulting efficiency gains are substantial, and represent an important step toward practical and efficient solar fuel production on a large scale.

An Exploratory Study of the Effects of Online Course Efficiency Perceptions on Student Evaluation of Teaching (SET) Measures

ERIC Educational Resources Information Center

Estelami, Hooman

2016-01-01

One of the fundamental drivers of the growing use of distance learning methods in modern business education has been the efficiency gains associated with this method of educational delivery. Distance methods benefit both students and educational institutions as they facilitate the processing of large volumes of learning material to overcome…

Measurement of basic characteristics and gain uniformity of a triple GEM detector

NASA Astrophysics Data System (ADS)

Patra, Rajendra Nath; Singaraju, Rama N.; Biswas, Saikat; Ahammed, Zubayer; Nayak, Tapan K.; Viyogi, Yogendra P.

2017-08-01

Large area Gas Electron Multiplier (GEM) detectors have been the preferred choice for tracking devices in major nuclear and particle physics experiments. Uniformity over surface of the detector in terms of gain, energy resolution and efficiency is crucial for the optimum performance of these detectors. In the present work, detailed performance study of a 10×10 cm2 triple GEM detector operated using Ar and CO2 gas mixtures in proportions of 70:30 and 90:10, has been made by making a voltage scan of the efficiency with 106Ru-Rh β-source and cosmic rays. The gain and energy resolution of the detector were studied using the X-ray spectrum of 55Fe source. The uniformity of the detector has been investigated by dividing the detector in 7×7 zones and measuring the gain and energy resolution at the centre of each zone. The variations of the gain and energy resolution have been found to be 8.8% and 6.7%, respectively. These studies are essential to characterise GEM detectors before their final use in the experiments.

Efficient Decoding With Steady-State Kalman Filter in Neural Interface Systems

PubMed Central

Malik, Wasim Q.; Truccolo, Wilson; Brown, Emery N.; Hochberg, Leigh R.

2011-01-01

The Kalman filter is commonly used in neural interface systems to decode neural activity and estimate the desired movement kinematics. We analyze a low-complexity Kalman filter implementation in which the filter gain is approximated by its steady-state form, computed offline before real-time decoding commences. We evaluate its performance using human motor cortical spike train data obtained from an intracortical recording array as part of an ongoing pilot clinical trial. We demonstrate that the standard Kalman filter gain converges to within 95% of the steady-state filter gain in 1.5 ± 0.5 s (mean ± s.d.). The difference in the intended movement velocity decoded by the two filters vanishes within 5 s, with a correlation coefficient of 0.99 between the two decoded velocities over the session length. We also find that the steady-state Kalman filter reduces the computational load (algorithm execution time) for decoding the firing rates of 25 ± 3 single units by a factor of 7.0 ± 0.9. We expect that the gain in computational efficiency will be much higher in systems with larger neural ensembles. The steady-state filter can thus provide substantial runtime efficiency at little cost in terms of estimation accuracy. This far more efficient neural decoding approach will facilitate the practical implementation of future large-dimensional, multisignal neural interface systems. PMID:21078582

Surface-emitting circular DFB, disk- and ring- Bragg resonator lasers with chirped gratings: a unified theory and comparative study.

PubMed

Sun, Xiankai; Yariv, Amnon

2008-06-09

We have developed a theory that unifies the analysis of the modal properties of surface-emitting chirped circular grating lasers. This theory is based on solving the resonance conditions which involve two types of reflectivities of chirped circular gratings. This approach is shown to be in agreement with previous derivations which use the characteristic equations. Utilizing this unified analysis, we obtain the modal properties of circular DFB, disk-, and ring- Bragg resonator lasers. We also compare the threshold gain, single mode range, quality factor, emission efficiency, and modal area of these types of circular grating lasers. It is demonstrated that, under similar conditions, disk Bragg resonator lasers have the highest quality factor, the highest emission efficiency, and the smallest modal area, indicating their suitability in low-threshold, high-efficiency, ultracompact laser design, while ring Bragg resonator lasers have a large single mode range, high emission efficiency, and large modal area, indicating their suitability for high-efficiency, large-area, high-power applications.

Modeling long-term carbon residue in the ocean-atmosphere system following large CO2 emissions

NASA Astrophysics Data System (ADS)

Towles, N. J.; Olson, P.; Gnanadesikan, A.

2013-12-01

We use the LOSCAR carbon cycle model (Zeebe et al., 2009; Zeebe, 2012) to calculate the residual carbon in the ocean and atmosphere following large CO2 emissions. We consider the system response to CO2 emissions ranging from 100 to 20000 PgC, and emission durations from 100 yr to 100 kyr, subject to a wide range of system parameters such as the strengths of silicate weathering and the oceanic biological carbon pump. We define the carbon gain factor as the ratio of residual carbon in the ocean-atmosphere to the total emitted carbon. For moderate sized emissions shorter than about 50 kyr, we find that the carbon gain factor grows during the emission and peaks at about 1.7, primarily due to the erosion of carbonate marine sediments. In contrast, for longer emissions, the carbon gain factor peaks at a smaller value, and for very large emissions (more than 5000 PgC), the gain factor decreases with emission size due to carbonate sediment exhaustion. This gain factor is sensitive to model parameters such as low latitude efficiency of the biological pump. The timescale for removal of the residual carbon (reducing the carbon gain factor to zero) depends strongly on the assumed sensitivity of silicate weathering to atmospheric pCO2, and ranges from less than one million years to several million years.

Review of health and productivity gains from better IEQ

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

Fisk, William J.

2000-08-01

The available scientific data suggest that existing technologies and procedures can improve indoor environmental quality (IEQ) in a manner that significantly increases productivity and health. While there is considerable uncertainty in the estimates of the magnitudes of productivity gains that may be obtained, the projected gains are very large. For the U.S., the estimated potential annual savings and productivity gains are $6 to $14 billion from reduced respiratory disease, $2 to $4 billion from reduced allergies and asthma, $10 to $30 billion from reduced sick building syndrome symptoms, and $20 to $160 billion from direct improvements in worker performance thatmore » are unrelated to health. Productivity gains that are quantified and demonstrated could serve as a strong stimulus for energy efficiency measures that simultaneously improve the indoor environment.« less

Genomic and genotyping characterization of haplotype-based polymorphic microsatellites in Prunus

USDA-ARS?s Scientific Manuscript database

Efficient utilization of microsatellites in genetic studies remains impeded largely due to the unknown status of their primer reliability, chromosomal location, and allele polymorphism. Discovery and characterization of microsatellite polymorphisms in a taxon will disclose the unknowns and gain new ...

The Role of Morphology and Electronic Chain Aggregation on the Optical Gain Properties of Semiconducting Conjugated Polymers

NASA Astrophysics Data System (ADS)

Lampert, Zachary Evan

Conjugated polymers (CPs) are a novel class of materials that exhibit the optical and electrical properties of semiconductors while still retaining the durability and processability of plastics. CPs are also intrinsically 4-level systems with high luminescence quantum efficiencies making them particularly attractive as organic gain media for solid-state laser applications. However, before CPs can emerge as a commercially available laser technology, a more comprehensive understanding of the morphological dependence of the photophysics is required. In this thesis, the morphology and chain conformation dependence of amplified spontaneous emission (ASE) and optical gain in thin films of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) was investigated. By changing the chemical nature of the solvent from which films were cast, as well as the temperature at which films were annealed, CP films with different morphologies, and hence different degrees of interchain interactions were achieved. Contrary to the common perception that polymer morphology plays a decisive role in determining the ASE behavior of thin CP films, we found that chromophore aggregation and degree of conformational order have minimal impact on optical gain. In fact, experimental results indicated that an extremely large fraction of interchain aggregate species and/or exciton dissociating defects are required to significantly alter the optical properties and suppress stimulated emission. These results are pertinent to the fabrication and optimization of an electrically pumped laser device, as improvements in charge carrier mobility through controlled increases in chain aggregation may provide a viable means of optimizing injection efficiency without significantly degrading optical gain. To offset charge-induced absorption losses under electrical pumping, and to enable the use of more compact and economical sources under optical pumping, conjugated polymers exhibiting low lasing thresholds and large net gains are highly desirable. In this thesis, we also discuss novel routes we developed for enhancement of ASE performance in MEH-PPV thin film planar waveguides. The first technique relied on improving the distribution of the TE0 guided mode in the CP gain layer through optimization of waveguide architecture. This was achieved by fabricating symmetric heterostructure waveguides formed from a core layer of MEH-PPV sandwiched between an SiO2 buffer and index matched poly(methyl methacrylate) (PMMA) cover layer. Relative to asymmetric waveguides of Si(100)/SiO2/MEH-PPV/Air, symmetric waveguides exhibited increased optical confinement and reduced propagation loss enabling lower ASE threshold (40%) and higher net gain (50%). Independent of device architecture and degree of aggregation in the films, we discovered that optical gain is also highly dependent on the excitation conditions, specifically the temporal width of the pump laser pulses. A 400% increase in net gain was achieved under transient (25 picosecond pulses), compared to quasi-steady state (8 nanosecond pulses), excitation conditions. This large difference is attributed to low pumping efficiency and increased non-radiative recombination under ns pumping, which reduces the emission cross-section resulting in a net decrease in gain. The gain values we achieved in the ps regime are to the best of our knowledge the largest gain values reported to date for thin conjugated polymer films measured using the variable stripe length (VSL) technique. Films pumped in the transient regime also required 30 times less pump energy density to reach threshold in comparison with films pumped in the quasi-steady state regime, although the excited state densities were essentially the same. These results demonstrate that the pumping efficiency, and hence generation rate of excited states in a gain medium, can be dramatically increased by using pump laser pulses that are shorter than the exciton luminescence lifetime

A novel biasing dependent circuit model of resonant cavity enhanced avalanche photodetectors (RCE-APDs)

NASA Astrophysics Data System (ADS)

Abdelhamid, Mostafa R.; El-Batawy, Yasser M.; Deen, M. Jamal

2018-02-01

In Resonant Cavity Enhanced Photodetectors (RCE-PDs), the trade-off between the bandwidth and the quantum efficiency in the conventional photodetectors is overcome. In RCE-PDs, large bandwidth can be achieved using a thin absorption layer while the use of a resonant cavity allows for multiple passes of light in the absorption which boosts the quantum efficiency. In this paper, a complete bias-dependent model for the Resonant Cavity Enhanced-Separated Absorption Graded Charge Multiplication-Avalanche Photodetector (RCE-SAGCM-APD) is presented. The proposed model takes into account the case of drift velocities other than the saturation velocity, thus modeling this effect on the photodetector different design parameters such as Gain, Bandwidth and Gain-Bandwidth product.

Partial Adaptation of Obtained and Observed Value Signals Preserves Information about Gains and Losses

PubMed Central

Baddeley, Michelle; Tobler, Philippe N.; Schultz, Wolfram

2016-01-01

Given that the range of rewarding and punishing outcomes of actions is large but neural coding capacity is limited, efficient processing of outcomes by the brain is necessary. One mechanism to increase efficiency is to rescale neural output to the range of outcomes expected in the current context, and process only experienced deviations from this expectation. However, this mechanism comes at the cost of not being able to discriminate between unexpectedly low losses when times are bad versus unexpectedly high gains when times are good. Thus, too much adaptation would result in disregarding information about the nature and absolute magnitude of outcomes, preventing learning about the longer-term value structure of the environment. Here we investigate the degree of adaptation in outcome coding brain regions in humans, for directly experienced outcomes and observed outcomes. We scanned participants while they performed a social learning task in gain and loss blocks. Multivariate pattern analysis showed two distinct networks of brain regions adapt to the most likely outcomes within a block. Frontostriatal areas adapted to directly experienced outcomes, whereas lateral frontal and temporoparietal regions adapted to observed social outcomes. Critically, in both cases, adaptation was incomplete and information about whether the outcomes arose in a gain block or a loss block was retained. Univariate analysis confirmed incomplete adaptive coding in these regions but also detected nonadapting outcome signals. Thus, although neural areas rescale their responses to outcomes for efficient coding, they adapt incompletely and keep track of the longer-term incentives available in the environment. SIGNIFICANCE STATEMENT Optimal value-based choice requires that the brain precisely and efficiently represents positive and negative outcomes. One way to increase efficiency is to adapt responding to the most likely outcomes in a given context. However, too strong adaptation would result in loss of precise representation (e.g., when the avoidance of a loss in a loss-context is coded the same as receipt of a gain in a gain-context). We investigated an intermediate form of adaptation that is efficient while maintaining information about received gains and avoided losses. We found that frontostriatal areas adapted to directly experienced outcomes, whereas lateral frontal and temporoparietal regions adapted to observed social outcomes. Importantly, adaptation was intermediate, in line with influential models of reference dependence in behavioral economics. PMID:27683899

Enhanced UV light detection using a p-terphenyl wavelength shifter

NASA Astrophysics Data System (ADS)

Joosten, S.; Kaczanowicz, E.; Ungaro, M.; Rehfuss, M.; Johnston, K.; Meziani, Z.-E.

2017-10-01

UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths below 300 nm due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below 300 nm. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between 200 nm and 400 nm. The gain factor ranges up to 5 . 4 ± 0 . 5 at a wavelength of 215 nm, with a material load of 110 ± 10 μg /cm2 (894 nm). The wavelength shifter was found to be fully transparent for wavelengths greater than 300 nm. The resulting gain in detection efficiency, when used in a typical C̆erenkov counter, was estimated to be of the order of 40%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based on these results, 200 Photonis XP4500B PMTs were treated with PT for the upgraded low-threshold C̆erenkov counter (LTCC) to be used in the CEBAF Large Acceptance Spectrometer upgraded detector (CLAS12) at the Thomas Jefferson National Accelerator Facility.

Designing a place for automation.

PubMed

Bazzoli, F

1995-05-01

Re-engineering is a hot topic in health care as market forces increase pressure to cut costs. Providers and payers that are redesigning their business processes are counting on information systems to help achieve simplification and make large gains in efficiency. But these same organizations say they're reluctant to make large upfront investments in information systems until they know exactly what role technology will play in the re-engineered entity.

Dynamics of Charge Carriers in Silicon Nanowire Photoconductors Revealed by Photo Hall Effect Measurements.

PubMed

Chen, Kaixiang; Zhao, Xiaolong; Mesli, Abdelmadjid; He, Yongning; Dan, Yaping

2018-04-24

Photoconductors have extraordinarily high gain in quantum efficiency, but the origin of the gain has remained in dispute for decades. In this work, we employ photo Hall effect to reveal the gain mechanisms by probing the dynamics of photogenerated charge carriers in silicon nanowire photoconductors. The results reveal that a large number of photogenerated minority electrons are localized in the surface depletion region and surface trap states. The same number of excess hole counterparts is left in the nanowire conduction channel, resulting in the fact that excess holes outnumber the excess electrons in the nanowire conduction channel by orders of magnitude. The accumulation of the excess holes broadens the conduction channel by narrowing down the depletion region, which leads to the experimentally observed high photo gain.

30/20 GHz spacecraft GaAs FET solid state transmitter for trunking and customer-premise-service application

NASA Technical Reports Server (NTRS)

Saunier, P.; Nelson, S.

1983-01-01

Sixteen 30 dB 0.5 W amplifier modules were combined to satisfy the requirement for a graceful degradation. If one module fails, the output power drops by only 0.43 dB. Also, by incorporating all the gain stages within the combiner the overall combining efficiency is maximized. A 16 way waveguide divider combiner was developed to minimize the insertion loss associated with such a large corporate feed structure. Tests showed that the 16 way insertion loss was less than 0.5 dB. To minimize loss, a direct transition from waveguide to microstrip, using a finline on duroid substrate, was developed. The FETs fabricated on MBE grown material, demonstrated superior performances. For example, a 600 micrometer device was capable of 320 mW output power with 5 dB gain and 26.6% efficiency at 21 GHz. The 16 module amplifier gave 8.95 W saturated output power with 30 dB gain. The overall efficiency was 9%. The 3 dB bandwidth was 2.5 GHz. At 17.7 GHz the amplifier had 5 W output power and at 20.2 GHz it still had 4.4 W.

Cladding pumped Yb-doped HOM power amplifier with high gain

NASA Astrophysics Data System (ADS)

Abedin, Kazi S.; Ahmad, Raja; DeSantolo, Anthony M.; Nicholson, Jeffrey W.; Westbrook, Paul S.; Headley, Clifford; DiGiovanni, David J.

2018-02-01

Higher-order mode (HOM) fibers have been engineered to allow propagation of linearly polarized symmetric modes LP0,N in a robust way. Compared with the fundamental mode LP(0,1), HOMs exhibits an effective area that can be larger by over two order magnitude, and thus propagating light in these modes could greatly suppress the effect of nonlinear effects. HOM fibers could also be doped with rare earth ions in order to amplify light propagating in these modes, which offers the enormous potential for generating high-intensity pulses. Excitation of HOM gain fiber using cladding pumping with multimode pump source is attractive for ytterbium based amplifiers, because of the availability of low-cost multimode pump diodes in the 975nm wavelength range. One problem associated with cladding pumping which leads to excitation of the large doped core (over 100 μm diameter) is that it could result in a large amount of amplifiedspontaneous- emission (ASE) noise, particularly when the input signal is weak. Optimization of amplifier design is critical in order to suppress ASE and achieve high gain and pump-to-signal conversion efficiency. We conducted numerical modeling of a cladding pumped HOM-amplifier, which revealed that this problem could be mitigated by using a relatively long gain-fiber that allowed reabsorption of the forward propagating ASE resulting in a further amplification of the signal. We demonstrate efficient amplification of a LP0,10 mode with an effective area 3140μm2 in an Yb-doped HOM amplifier cladding pumped at 975nm. We have successfully obtained a 20.2dB gain for 0.95 W 1064 nm input seed signal to more than 105W.

Foraging ecology

USGS Publications Warehouse

Tinker, M. Tim; Estes, James A.; Staedler, Michelle; Bodkin, James L.; Tinker, M. Tim; Estes, James A.; Ralls, Katherine; Williams, Terrie M.; Jessup, David A.; Costa, Daniel P.

2006-01-01

Longitudinal foraging data collected from 60 sea otters implanted with VHF radio transmitters at two study sites in Central California over a three-year period demonstrated even greater individual dietary specialization than in previous studies, with only 54% dietary overlap between individuals and the population.Multivariate statistical analyses indicated that individual diets could be grouped into three general "diet types" representing distinct foraging specializations. Type 1 specialists consumed large size prey but had low dive efficiency, Type 2 specialists consumed small to medium size prey with high dive efficiency, and Type 3 specialists consumed very small prey (mainly snails) with very high dive efficiency.The mean rate of energy gain for the population as a whole was low when compared to other sea otter populations in Alaska but showed a high degree of within- and betweenindividual variation, much of which was accounted for by the three foraging strategies. Type 1 specialists had the highest mean energy gain but also the highest withinindividual variance in energy gain. Type 2 specialists had the lowest mean energy gain but also the lowest variance. Type 3 specialists had an intermediate mean and variance. All three strategies resulted in very similar probabilities of exceeding a critical rate of energy gain on any given day.Correlational selection may help maintain multiple foraging strategies in the population: a fitness surface (using mean rate of energy gain as a proxy for fitness) fit to the first two principal components of foraging behavior suggested that the three foraging strategies occupy separate fitness peaks.Food limitation is likely an important ultimate factor restricting population growth in the center of the population’s range in California, although the existence of alternative foraging strategies results in different impacts of food limitation on individuals and thus may obscure expected patterns of density dependence.

Optimal auxiliary-covariate-based two-phase sampling design for semiparametric efficient estimation of a mean or mean difference, with application to clinical trials.

PubMed

Gilbert, Peter B; Yu, Xuesong; Rotnitzky, Andrea

2014-03-15

To address the objective in a clinical trial to estimate the mean or mean difference of an expensive endpoint Y, one approach employs a two-phase sampling design, wherein inexpensive auxiliary variables W predictive of Y are measured in everyone, Y is measured in a random sample, and the semiparametric efficient estimator is applied. This approach is made efficient by specifying the phase two selection probabilities as optimal functions of the auxiliary variables and measurement costs. While this approach is familiar to survey samplers, it apparently has seldom been used in clinical trials, and several novel results practicable for clinical trials are developed. We perform simulations to identify settings where the optimal approach significantly improves efficiency compared to approaches in current practice. We provide proofs and R code. The optimality results are developed to design an HIV vaccine trial, with objective to compare the mean 'importance-weighted' breadth (Y) of the T-cell response between randomized vaccine groups. The trial collects an auxiliary response (W) highly predictive of Y and measures Y in the optimal subset. We show that the optimal design-estimation approach can confer anywhere between absent and large efficiency gain (up to 24 % in the examples) compared to the approach with the same efficient estimator but simple random sampling, where greater variability in the cost-standardized conditional variance of Y given W yields greater efficiency gains. Accurate estimation of E[Y | W] is important for realizing the efficiency gain, which is aided by an ample phase two sample and by using a robust fitting method. Copyright © 2013 John Wiley & Sons, Ltd.

Optimal Auxiliary-Covariate Based Two-Phase Sampling Design for Semiparametric Efficient Estimation of a Mean or Mean Difference, with Application to Clinical Trials

PubMed Central

Gilbert, Peter B.; Yu, Xuesong; Rotnitzky, Andrea

2014-01-01

To address the objective in a clinical trial to estimate the mean or mean difference of an expensive endpoint Y, one approach employs a two-phase sampling design, wherein inexpensive auxiliary variables W predictive of Y are measured in everyone, Y is measured in a random sample, and the semi-parametric efficient estimator is applied. This approach is made efficient by specifying the phase-two selection probabilities as optimal functions of the auxiliary variables and measurement costs. While this approach is familiar to survey samplers, it apparently has seldom been used in clinical trials, and several novel results practicable for clinical trials are developed. Simulations are performed to identify settings where the optimal approach significantly improves efficiency compared to approaches in current practice. Proofs and R code are provided. The optimality results are developed to design an HIV vaccine trial, with objective to compare the mean “importance-weighted” breadth (Y) of the T cell response between randomized vaccine groups. The trial collects an auxiliary response (W) highly predictive of Y, and measures Y in the optimal subset. We show that the optimal design-estimation approach can confer anywhere between absent and large efficiency gain (up to 24% in the examples) compared to the approach with the same efficient estimator but simple random sampling, where greater variability in the cost-standardized conditional variance of Y given W yields greater efficiency gains. Accurate estimation of E[Y∣W] is important for realizing the efficiency gain, which is aided by an ample phase-two sample and by using a robust fitting method. PMID:24123289

Development of a 39.5 GHz Karp traveling wave tube for use in space

NASA Technical Reports Server (NTRS)

Jacquez, A.; Wilson, D.

1988-01-01

A millimeter-wave TWT was developed using a dispersive, high-impedance forward wave interaction structure based on a ladder, with non-space-harmonic interaction, for a tube with high gain per inch and high efficiency. The 'Tunneladder' interaction structure combines ladder properties modified to accommodate Pierce gun beam optics on a radially magnetized PM focusing structure. The development involved the fabrication of chemically milled, shaped ladders diffusion brazed to each ridge of a double ridged waveguide. Cold-test data are presented, representing the omega-Beta and impedance characteristics of the modified ladder circuit These results were used in small and large-signal computer programs to predict TWT gain and efficiency. A laboratory model tube was designed and fabricated, including all major subassemblies.

Space Power Amplification with Active Linearly Tapered Slot Antenna Array

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Lee, Richard Q.

1993-01-01

A space power amplifier composed of active linearly tapered slot antennas (LTSA's) has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. The LTSA and the MMIC power amplifier has a gain of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using monolithic integration techniques.

Beyond the limits of present active matrix flat-panel imagers (AMFPIs) for diagnostic radiology

NASA Astrophysics Data System (ADS)

Antonuk, Larry E.; El-Mohri, Youcef; Jee, Kyung-Wook; Maolinbay, Manat; Nassif, Samer C.; Rong, Xiujiang; Siewerdsen, Jeffrey H.; Zhao, Qihua; Street, Robert A.

1999-05-01

A theoretical cascaded systems analysis of the performance limits of x-ray imagers based on thin-film, active matrix flat-panel technology is presented. This analysis specifically focuses upon an examination of the functional dependence of the detective quantum efficiency on exposure. While the DQE of AMFPI systems is relatively high at the large exposure levels associated with radiographic x-ray imaging, there is a significant decline in DQE with decreasing exposure over the medium and lower end of the exposure range associated with fluoroscopic imaging. This fall-off in DQE originates from the relatively large size of the additive noise of AMFPI systems compared to their overall system gain. Therefore, strategies to diminish additive noise and increase system gain should significantly improve performance. Potential strategies for noise reduction include the use of charge compensation lines while strategies for gain enhancement include continuous photodiodes, pixel amplification structures, or higher gain converters. The effect of the implementation of such strategies is examined for a variety for hypothetical imager configurations. Through the modeling of these configurations, such enhancements are shown to hold the potential of making low frequency DQE response large and essentially independent of exposure while greatly reducing the fall-off in DQE at higher spatial frequencies.

Enhanced UV light detection using a p-terphenyl wavelength shifter

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

Joosten, Sylvester J.; Kaczanowicz, Ed; Ungaro, Maurizio

Here, UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths belowmore » $$300\\,\\text{nm}$$ due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below $$300\\,\\text{nm}$$. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between $$200\\,\\text{nm}$$ and $$400\\,\\text{nm}$$. The gain factor ranges up to 5.4 $$\\pm$$ 0.5 at a wavelength of $$215\\,\\text{nm}$$, with a material load of $$110\\pm10\\,\\mu\\text{g}/\\text{cm}^2$$ ($$894\\,\\text{nm}$$). The wavelength shifter was found to be fully transparent for wavelengths greater than $$300\\,\\text{nm}$$. The resulting gain in detection efficiency, when used in a typical Cherenkov counter, was estimated to be of the order of 40%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based on these results, 200 Photonis XP4500B PMTs were treated with PT for the upgraded low-threshold Cherenkov counter (LTCC) to be used in the CEBAF Large Acceptance Spectrometer upgraded detector (CLAS12) at the Thomas Jefferson National Accelerator Facility.« less

Enhanced UV light detection using a p-terphenyl wavelength shifter

DOE PAGES

Joosten, Sylvester J.; Kaczanowicz, Ed; Ungaro, Maurizio; ...

2017-07-25

Here, UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths belowmore » $$300\\,\\text{nm}$$ due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below $$300\\,\\text{nm}$$. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between $$200\\,\\text{nm}$$ and $$400\\,\\text{nm}$$. The gain factor ranges up to 5.4 $$\\pm$$ 0.5 at a wavelength of $$215\\,\\text{nm}$$, with a material load of $$110\\pm10\\,\\mu\\text{g}/\\text{cm}^2$$ ($$894\\,\\text{nm}$$). The wavelength shifter was found to be fully transparent for wavelengths greater than $$300\\,\\text{nm}$$. The resulting gain in detection efficiency, when used in a typical Cherenkov counter, was estimated to be of the order of 40%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based on these results, 200 Photonis XP4500B PMTs were treated with PT for the upgraded low-threshold Cherenkov counter (LTCC) to be used in the CEBAF Large Acceptance Spectrometer upgraded detector (CLAS12) at the Thomas Jefferson National Accelerator Facility.« less

Secure and Robust Overlay Content Distribution

ERIC Educational Resources Information Center

Kang, Hun Jeong

2010-01-01

With the success of applications spurring the tremendous increase in the volume of data transfer, efficient and reliable content distribution has become a key issue. Peer-to-peer (P2P) technology has gained popularity as a promising approach to large-scale content distribution due to its benefits including self-organizing, load-balancing, and…

Incentives for vertical integration in healthcare: the effect of reimbursement systems.

PubMed

Byrne, M M; Ashton, C M

1999-01-01

In the United States, many healthcare organizations are being transformed into large integrated delivery systems, even though currently available empirical evidence does not provide strong or unequivocal support for or against vertical integration. Unfortunately, the manager cannot delay organizational changes until further research has been completed, especially when further research is not likely to reveal a single, correct solution for the diverse healthcare systems in existence. Managers must therefore carefully evaluate the expected effects of integration on their individual organizations. Vertical integration may be appropriate if conditions facing the healthcare organization provide opportunities for efficiency gains through reorganization strategies. Managers must consider (1) how changes in the healthcare market have affected the dynamics of production efficiency and transaction costs; (2) the likelihood that integration strategies will achieve increases in efficiency or reductions in transaction costs; and (3) how vertical integration will affect other costs, and whether the benefits gained will outweigh additional costs and efficiency losses. This article presents reimbursement systems as an example of how recent changes in the industry may have changed the dynamics and efficiency of production. Evaluation of the effects of vertical integration should allow for reasonable adjustment time, but obviously unsuccessful strategies should not be followed or maintained.

Trap-assisted large gain in Cu{sub 2}O/C{sub 60} hybrid ultraviolet/visible photodetectors

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

Liu, Lan; Xi, Qiaoyue; Gao, Ge

2016-04-18

Photomultiplication-type ultraviolet (UV)/visible photodetectors (PDs) are demonstrated in an electrodeposited Cu{sub 2}O/C{sub 60} hybrid structure. These simple organic/inorganic hybrid PDs exhibit external quantum efficiencies (EQEs) of 1.1 × 10{sup 4}% under illumination of 365 nm UV light at −3 V, indicating a large gain of photocurrent for these devices. Such an EQE is one of the highest values among the reported organic/inorganic hybrid PDs at the same voltage. Cu{sub 2}O and C{sub 60} are found to play different roles in realizing the photomultiplication. Copper vacancies are proposed as the defects in the electrodeposited Cu{sub 2}O layers, which can trap photogenerated holes. Such trapped holesmore » will trigger the injection of multiple electrons and hence result in the photocurrent gain of the devices while C{sub 60} primarily acts as a light absorption media to provide free holes.« less

Magnetically Controlled Variable Transformer

NASA Technical Reports Server (NTRS)

Kleiner, Charles T.

1994-01-01

Improved variable-transformer circuit, output voltage and current of which controlled by use of relatively small current supplied at relatively low power to control windings on its magnetic cores. Transformer circuits of this type called "magnetic amplifiers" because ratio between controlled output power and power driving control current of such circuit large. This ratio - power gain - can be as large as 100 in present circuit. Variable-transformer circuit offers advantages of efficiency, safety, and controllability over some prior variable-transformer circuits.

A millimeter-wave tunneLadder TWT

NASA Technical Reports Server (NTRS)

Jacquez, A.; Karp, A.; Wilson, D.; Scott, A.

1988-01-01

A millimeter wave traveling wave tube was developed using a dispersive, high impedance forward interaction structure based on a ladder, with non-space harmonic interaction, for a tube with high gain per unit length and high efficiency. The TunneLadder interaction structure combines ladder properties modified to accommodate Pierce gun beam optics in a radially magnetized permanent magnet focusing structure. The development involved the fabrication of chemically milled, shaped ladders diffusion brazed to diamond cubes which are in turn active-diffusion brazed to each ridge of a doubly ridged waveguide. Cold test data are presented, representing the omega-beta and impedance characteristics of the modified ladder circuit. These results were used in small and large signal computer programs to predict TWT gain and efficiency. Actual data from tested tubes verify the predicted performance while providing broader bandwidth than expected.

A millimeter-wave tunneladder TWT

NASA Technical Reports Server (NTRS)

Wilson, D.

1988-01-01

A millimeter-wave traveling wave tube (TWT) was developed using a dispersive, high-impedance forward wave interaction structure based on a ladder, with non-space-harmonic interaction, for a tube with high gain per inch and high efficiency. The 'TunneLadder' interaction structure combines ladder properties modified to accommodate Pierce gun beam optics in a radially magnetized PM focusing structure. The development involved the fabrication of chemically milled, shaped ladders diffusion brazed to diamond cubes which are in turn active diffusion brazed to each ridge of a doubly ridged waveguide. Cold-test data, representing the (omega)(beta) and and impedance characteristics of the modified ladder circuit, were used in small and large-signal computer programs to predict TWT gain and efficiency. The structural design emphasizes ruggedness and reliability. Actual data from tested tubes verify the predicted performance while providing broader bandwidth than expected.

A numerical algorithm for optimal feedback gains in high dimensional linear quadratic regulator problems

NASA Technical Reports Server (NTRS)

Banks, H. T.; Ito, K.

1991-01-01

A hybrid method for computing the feedback gains in linear quadratic regulator problem is proposed. The method, which combines use of a Chandrasekhar type system with an iteration of the Newton-Kleinman form with variable acceleration parameter Smith schemes, is formulated to efficiently compute directly the feedback gains rather than solutions of an associated Riccati equation. The hybrid method is particularly appropriate when used with large dimensional systems such as those arising in approximating infinite-dimensional (distributed parameter) control systems (e.g., those governed by delay-differential and partial differential equations). Computational advantages of the proposed algorithm over the standard eigenvector (Potter, Laub-Schur) based techniques are discussed, and numerical evidence of the efficacy of these ideas is presented.

A numerical algorithm for optimal feedback gains in high dimensional LQR problems

NASA Technical Reports Server (NTRS)

Banks, H. T.; Ito, K.

1986-01-01

A hybrid method for computing the feedback gains in linear quadratic regulator problems is proposed. The method, which combines the use of a Chandrasekhar type system with an iteration of the Newton-Kleinman form with variable acceleration parameter Smith schemes, is formulated so as to efficiently compute directly the feedback gains rather than solutions of an associated Riccati equation. The hybrid method is particularly appropriate when used with large dimensional systems such as those arising in approximating infinite dimensional (distributed parameter) control systems (e.g., those governed by delay-differential and partial differential equations). Computational advantage of the proposed algorithm over the standard eigenvector (Potter, Laub-Schur) based techniques are discussed and numerical evidence of the efficacy of our ideas presented.

Predicting the performance of a power amplifier using large-signal circuit simulations of an AlGaN/GaN HFET model

NASA Astrophysics Data System (ADS)

Bilbro, Griff L.; Hou, Danqiong; Yin, Hong; Trew, Robert J.

2009-02-01

We have quantitatively modeled the conduction current and charge storage of an HFET in terms its physical dimensions and material properties. For DC or small-signal RF operation, no adjustable parameters are necessary to predict the terminal characteristics of the device. Linear performance measures such as small-signal gain and input admittance can be predicted directly from the geometric structure and material properties assumed for the device design. We have validated our model at low-frequency against experimental I-V measurements and against two-dimensional device simulations. We discuss our recent extension of our model to include a larger class of electron velocity-field curves. We also discuss the recent reformulation of our model to facilitate its implementation in commercial large-signal high-frequency circuit simulators. Large signal RF operation is more complex. First, the highest CW microwave power is fundamentally bounded by a brief, reversible channel breakdown in each RF cycle. Second, the highest experimental measurements of efficiency, power, or linearity always require harmonic load pull and possibly also harmonic source pull. Presently, our model accounts for these facts with an adjustable breakdown voltage and with adjustable load impedances and source impedances for the fundamental frequency and its harmonics. This has allowed us to validate our model for large signal RF conditions by simultaneously fitting experimental measurements of output power, gain, and power added efficiency of real devices. We show that the resulting model can be used to compare alternative device designs in terms of their large signal performance, such as their output power at 1dB gain compression or their third order intercept points. In addition, the model provides insight into new device physics features enabled by the unprecedented current and voltage levels of AlGaN/GaN HFETs, including non-ohmic resistance in the source access regions and partial depletion of the 2DEG in the drain access region.

RNA-Seq Meta-analysis identifies genes in skeletal muscle associated with gain and intake across a multi-season study of crossbred beef steers.

PubMed

Keel, Brittney N; Zarek, Christina M; Keele, John W; Kuehn, Larry A; Snelling, Warren M; Oliver, William T; Freetly, Harvey C; Lindholm-Perry, Amanda K

2018-06-04

Feed intake and body weight gain are economically important inputs and outputs of beef production systems. The purpose of this study was to discover differentially expressed genes that will be robust for feed intake and gain across a large segment of the cattle industry. Transcriptomic studies often suffer from issues with reproducibility and cross-validation. One way to improve reproducibility is by integrating multiple datasets via meta-analysis. RNA sequencing (RNA-Seq) was performed on longissimus dorsi muscle from 80 steers (5 cohorts, each with 16 animals) selected from the outside fringe of a bivariate gain and feed intake distribution to understand the genes and pathways involved in feed efficiency. In each cohort, 16 steers were selected from one of four gain and feed intake phenotypes (n = 4 per phenotype) in a 2 × 2 factorial arrangement with gain and feed intake as main effect variables. Each cohort was analyzed as a single experiment using a generalized linear model and results from the 5 cohort analyses were combined in a meta-analysis to identify differentially expressed genes (DEG) across the cohorts. A total of 51 genes were differentially expressed for the main effect of gain, 109 genes for the intake main effect, and 11 genes for the gain x intake interaction (P corrected  < 0.05). A jackknife sensitivity analysis showed that, in general, the meta-analysis produced robust DEGs for the two main effects and their interaction. Pathways identified from over-represented genes included mitochondrial energy production and oxidative stress pathways for the main effect of gain due to DEG including GPD1, NDUFA6, UQCRQ, ACTC1, and MGST3. For intake, metabolic pathways including amino acid biosynthesis and degradation were identified, and for the interaction analysis the pathways identified included GADD45, pyridoxal 5'phosphate salvage, and caveolar mediated endocytosis signaling. Variation among DEG identified by cohort suggests that environment and breed may play large roles in the expression of genes associated with feed efficiency in the muscle of beef cattle. Meta-analyses of transcriptome data from groups of animals over multiple cohorts may be necessary to elucidate the genetics contributing these types of biological phenotypes.

High Power SiGe X-Band (8-10 GHz) Heterojunction Bipolar Transistors and Amplifiers

NASA Technical Reports Server (NTRS)

Ma, Zhenqiang; Jiang, Ningyue; Ponchak, George E.; Alterovitz, Samuel A.

2005-01-01

Limited by increased parasitics and thermal effects as the device size becomes large, current commercial SiGe power HBTs are difficult to operate at X-band (8-12 GHz) with adequate power added efficiencies at high power levels. We found that, by changing the heterostructure and doping profile of SiGe HBTs, their power gain can be significantly improved without resorting to substantial lateral scaling. Furthermore, employing a common-base configuration with proper doping profile instead of a common-emitter configuration improves the power gain characteristics of SiGe HBTs, which thus permits these devices to be efficiently operated at X-band. In this paper, we report the results of SiGe power HBTs and MMIC power amplifiers operating at 8-10 GHz. At 10 GHz, 22.5 dBm (178 mW) RF output power with concurrent gain of 7.32 dB is measured at the peak power-added efficiency of 20.0% and the maximum RF output power of 24.0 dBm (250 mW) is achieved from a 20 emitter finger SiGe power HBT. Demonstration of single-stage X-band medium-power linear MMIC power amplifier is also realized at 8 GHz. Employing a 10-emitter finger SiGe HBT and on-chip input and output matching passive components, a linear gain of 9.7 dB, a maximum output power of 23.4 dBm and peak power added efficiency of 16% is achieved from the power amplifier. The MMIC exhibits very low distortion with third order intermodulation (IM) suppression C/I of -13 dBc at output power of 21.2 dBm and over 20dBm third order output intercept point (OIP3).

Development of high-sensitivity SWIR APD receivers

NASA Astrophysics Data System (ADS)

Bai, Xiaogang; Yuan, Ping; Chang, James; Sudharsanan, Rengarajan; Krainak, Michael; Yang, Guangning; Sun, Xiaoli; Lu, Wei

2013-06-01

Emerging short wavelength infrared (SWIR) LIght Detection And Ranging (LIDAR) and long range laser rangefinder systems, require large optical aperture avalanche photodiodes (APDs) receivers with high sensitivity and high bandwidth. A large optical aperture is critical to increase the optical coupling efficiency and extend the LIDAR sensing range of the above systems. Both APD excess noise and transimpedance amplifier (TIA) noise need to be reduced in order to achieve high receiver sensitivity. The dark current and capacitance of large area APDs increase with APD aperture and thus limit the sensitivity and bandwidth of receivers. Spectrolab has been developing low excess noise InAlAs/InGaAs APDs with impact ionization engineering (I2E) designs for many years and has demonstrated APDs with optical gain over 100 utilizing multiple period I2E structures in the APD multiplier. These high gain I2E APDs have an excess noise factor less than 0.15. With an optical aperture of 200 μm, low excess noise multiple periods I2E APDs have capacitances about 1.7 pF. In addition, optical gains of InAlAs based APDs show very little temperature dependence and will enable APD photoreceivers without thermal electric cooling.

[Experience with the clinical use of the PKS-25 and KTs-28 suturing devices].

PubMed

Kalinina, T V

1976-01-01

A study of the experience gained during many years of use in the surgical practice of a stitcher PKS-25 for establishing esophageal-intestinal anastomoses and of the KTs-28 apparatus for anastomosing the colon with superjacent segments of the large intestine proved their efficient performance. Their utilization makes it possible to reduce the percentage of lethal outcomes due to inadequacy of the anastomosis sutures following operations involving gastrectomy, resection of the cardia, esophagus and segments of the large intestine.

Commentary: Environmental nanophotonics and energy

NASA Astrophysics Data System (ADS)

Smith, Geoff B.

2011-01-01

The reasons nanophotonics is proving central to meeting the need for large gains in energy efficiency and renewable energy supply are analyzed. It enables optimum management and use of environmental energy flows at low cost and on a sufficient scale by providing spectral, directional and temporal control in tune with radiant flows from the sun, and the local atmosphere. Benefits and problems involved in large scale manufacture and deployment are discussed including how managing and avoiding safety issues in some nanosystems will occur, a process long established in nature.

Genetic relationships between feed efficiency in growing males and beef cow performance.

PubMed

Crowley, J J; Evans, R D; Mc Hugh, N; Kenny, D A; McGee, M; Crews, D H; Berry, D P

2011-11-01

Most studies on feed efficiency in beef cattle have focused on performance in young animals despite the contribution of the cow herd to overall profitability of beef production systems. The objective of this study was to quantify, using a large data set, the genetic covariances between feed efficiency in growing animals measured in a performance-test station, and beef cow performance including fertility, survival, calving traits, BW, maternal weaning weight, cow price, and cull cow carcass characteristics in commercial herds. Feed efficiency data were available on 2,605 purebred bulls from 1 test station. Records on cow performance were available on up to 94,936 crossbred beef cows. Genetic covariances were estimated using animal and animal-dam linear mixed models. Results showed that selection for feed efficiency, defined as feed conversion ratio (FCR) or residual BW gain (RG), improved maternal weaning weight as evidenced by the respective genetic correlations of -0.61 and 0.57. Despite residual feed intake (RFI) being phenotypically independent of BW, a negative genetic correlation existed between RFI and cow BW (-0.23; although the SE of 0.31 was large). None of the feed efficiency traits were correlated with fertility, calving difficulty, or perinatal mortality. However, genetic correlations estimated between age at first calving and FCR (-0.55 ± 0.14), Kleiber ratio (0.33 ± 0.15), RFI (-0.29 ± 0.14), residual BW gain (0.36 ± 0.15), and relative growth rate (0.37 ± 0.15) all suggest that selection for improved efficiency may delay the age at first calving, and we speculate, using information from other studies, that this may be due to a delay in the onset of puberty. Results from this study, based on the estimated genetic correlations, suggest that selection for improved feed efficiency will have no deleterious effect on cow performance traits with the exception of delaying the age at first calving.

Tandem luminescent solar concentrators based on engineered quantum dots

NASA Astrophysics Data System (ADS)

Wu, Kaifeng; Li, Hongbo; Klimov, Victor I.

2018-02-01

Luminescent solar concentrators (LSCs) can serve as large-area sunlight collectors for terrestrial and space-based photovoltaics. Due to their high emission efficiencies and readily tunable emission and absorption spectra, colloidal quantum dots have emerged as a new and promising type of LSC fluorophore. Spectral tunability of the quantum dots also facilitates the realization of stacked multilayered LSCs, where enhanced performance is obtained through spectral splitting of incident sunlight, as in multijunction photovoltaics. Here, we demonstrate a large-area (>230 cm2) tandem LSC based on two types of nearly reabsorption-free quantum dots spectrally tuned for optimal solar-spectrum splitting. This prototype device exhibits a high optical quantum efficiency of 6.4% for sunlight illumination and solar-to-electrical power conversion efficiency of 3.1%. The efficiency gains due to the tandem architecture over single-layer devices quickly increase with increasing LSC size and can reach more than 100% in structures with window sizes of more than 2,500 cm2.

Enhancing the transmission efficiency by edge deletion in scale-free networks

NASA Astrophysics Data System (ADS)

Zhang, Guo-Qing; Wang, Di; Li, Guo-Jie

2007-07-01

How to improve the transmission efficiency of Internet-like packet switching networks is one of the most important problems in complex networks as well as for the Internet research community. In this paper we propose a convenient method to enhance the transmission efficiency of scale-free networks dramatically by kicking out the edges linking to nodes with large betweenness, which we called the “black sheep.” The advantages of our method are of facility and practical importance. Since the black sheep edges are very costly due to their large bandwidth, our method could decrease the cost as well as gain higher throughput of networks. Moreover, we analyze the curve of the largest betweenness on deleting more and more black sheep edges and find that there is a sharp transition at the critical point where the average degree of the nodes ⟨k⟩→2 .

Indium gallium arsenide microwave power transistors

NASA Technical Reports Server (NTRS)

Johnson, Gregory A.; Kapoor, Vik J.; Shokrani, Mohsen; Messick, Louis J.; Nguyen, Richard

1991-01-01

Depletion-mode InGaAs microwave power MISFETs with 1-micron gate lengths and up to 1-mm gate widths have been fabricated using an ion-implantation process. The devices employed a plasma-deposited silicon/silicon dioxide gate insulator. The dc I-V characteristics and RF power performance at 9.7 GHz are presented. The output power, power-added efficiency, and power gain as a function of input power are reported. An output power of 1.07 W with a corresponding power gain and power-added efficiency of 4.3 dB and 38 percent, respectively, was obtained. The large-gate-width devices provided over twice the previously reported output power for InGaAs MISFETs at X-band. In addition, output power stability within 1.2 percent over 24 h of continuous operation was achieved. In addition, a drain current drift of 4 percent over 10,000 sec was obtained.

Massive MIMO-OFDM indoor visible light communication system downlink architecture design

NASA Astrophysics Data System (ADS)

Lang, Tian; Li, Zening; Chen, Gang

2014-10-01

Multiple-input multiple-output (MIMO) technique is now used in most new broadband communication system, and orthogonal frequency division multiplexing (OFDM) is also utilized within current 4th generation (4G) of mobile telecommunication technology. With MIMO and OFDM combined, visible light communication (VLC) system's diversity gain is increase, yet system capacity for dispersive channels is also enhanced. Moreover, with the emerging massive MIMO-OFDM VLC system, there are significant advantages than smaller systems' such as channel hardening, further increasing of energy efficiency (EE) and spectral efficiency (SE) based on law of large number. This paper addresses one of the major technological challenges, system architecture design, which was solved by semispherical beehive structure (SBS) receiver and so that diversity gain can be identified and applied in Massive MIMO VLC system. Simulation results shows that the proposed design clearly presents a spatial diversity over conventional VLC systems.

Optimal designs for copula models

PubMed Central

Perrone, E.; Müller, W.G.

2016-01-01

Copula modelling has in the past decade become a standard tool in many areas of applied statistics. However, a largely neglected aspect concerns the design of related experiments. Particularly the issue of whether the estimation of copula parameters can be enhanced by optimizing experimental conditions and how robust all the parameter estimates for the model are with respect to the type of copula employed. In this paper an equivalence theorem for (bivariate) copula models is provided that allows formulation of efficient design algorithms and quick checks of whether designs are optimal or at least efficient. Some examples illustrate that in practical situations considerable gains in design efficiency can be achieved. A natural comparison between different copula models with respect to design efficiency is provided as well. PMID:27453616

A simulation-based efficiency comparison of AC and DC power distribution networks in commercial buildings

DOE PAGES

Gerber, Daniel L.; Vossos, Vagelis; Feng, Wei; ...

2017-06-12

Direct current (DC) power distribution has recently gained traction in buildings research due to the proliferation of on-site electricity generation and battery storage, and an increasing prevalence of internal DC loads. The research discussed in this paper uses Modelica-based simulation to compare the efficiency of DC building power distribution with an equivalent alternating current (AC) distribution. The buildings are all modeled with solar generation, battery storage, and loads that are representative of the most efficient building technology. A variety of paramet ric simulations determine how and when DC distribution proves advantageous. These simulations also validate previous studies that use simplermore » approaches and arithmetic efficiency models. This work shows that using DC distribution can be considerably more efficient: a medium sized office building using DC distribution has an expected baseline of 12% savings, but may also save up to 18%. In these results, the baseline simulation parameters are for a zero net energy (ZNE) building that can island as a microgrid. DC is most advantageous in buildings with large solar capacity, large battery capacity, and high voltage distribution.« less

A simulation-based efficiency comparison of AC and DC power distribution networks in commercial buildings

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

Gerber, Daniel L.; Vossos, Vagelis; Feng, Wei

Direct current (DC) power distribution has recently gained traction in buildings research due to the proliferation of on-site electricity generation and battery storage, and an increasing prevalence of internal DC loads. The research discussed in this paper uses Modelica-based simulation to compare the efficiency of DC building power distribution with an equivalent alternating current (AC) distribution. The buildings are all modeled with solar generation, battery storage, and loads that are representative of the most efficient building technology. A variety of paramet ric simulations determine how and when DC distribution proves advantageous. These simulations also validate previous studies that use simplermore » approaches and arithmetic efficiency models. This work shows that using DC distribution can be considerably more efficient: a medium sized office building using DC distribution has an expected baseline of 12% savings, but may also save up to 18%. In these results, the baseline simulation parameters are for a zero net energy (ZNE) building that can island as a microgrid. DC is most advantageous in buildings with large solar capacity, large battery capacity, and high voltage distribution.« less

Source-gated transistors for order-of-magnitude performance improvements in thin-film digital circuits

NASA Astrophysics Data System (ADS)

Sporea, R. A.; Trainor, M. J.; Young, N. D.; Shannon, J. M.; Silva, S. R. P.

2014-03-01

Ultra-large-scale integrated (ULSI) circuits have benefited from successive refinements in device architecture for enormous improvements in speed, power efficiency and areal density. In large-area electronics (LAE), however, the basic building-block, the thin-film field-effect transistor (TFT) has largely remained static. Now, a device concept with fundamentally different operation, the source-gated transistor (SGT) opens the possibility of unprecedented functionality in future low-cost LAE. With its simple structure and operational characteristics of low saturation voltage, stability under electrical stress and large intrinsic gain, the SGT is ideally suited for LAE analog applications. Here, we show using measurements on polysilicon devices that these characteristics lead to substantial improvements in gain, noise margin, power-delay product and overall circuit robustness in digital SGT-based designs. These findings have far-reaching consequences, as LAE will form the technological basis for a variety of future developments in the biomedical, civil engineering, remote sensing, artificial skin areas, as well as wearable and ubiquitous computing, or lightweight applications for space exploration.

Source-gated transistors for order-of-magnitude performance improvements in thin-film digital circuits

PubMed Central

Sporea, R. A.; Trainor, M. J.; Young, N. D.; Shannon, J. M.; Silva, S. R. P.

2014-01-01

Ultra-large-scale integrated (ULSI) circuits have benefited from successive refinements in device architecture for enormous improvements in speed, power efficiency and areal density. In large-area electronics (LAE), however, the basic building-block, the thin-film field-effect transistor (TFT) has largely remained static. Now, a device concept with fundamentally different operation, the source-gated transistor (SGT) opens the possibility of unprecedented functionality in future low-cost LAE. With its simple structure and operational characteristics of low saturation voltage, stability under electrical stress and large intrinsic gain, the SGT is ideally suited for LAE analog applications. Here, we show using measurements on polysilicon devices that these characteristics lead to substantial improvements in gain, noise margin, power-delay product and overall circuit robustness in digital SGT-based designs. These findings have far-reaching consequences, as LAE will form the technological basis for a variety of future developments in the biomedical, civil engineering, remote sensing, artificial skin areas, as well as wearable and ubiquitous computing, or lightweight applications for space exploration. PMID:24599023

Influence of the helium-pressure on diode-pumped alkali-vapor laser

NASA Astrophysics Data System (ADS)

Gao, Fei; Chen, Fei; Xie, Ji-jiang; Zhang, Lai-ming; Li, Dian-jun; Yang, Gui-long; Guo, Jing

2013-05-01

Diode-pumped alkali-vapor laser (DPAL) is a kind of laser attracted much attention for its merits, such as high quantum efficiency, excellent beam quality, favorable thermal management, and potential scalability to high power and so on. Based on the rate-equation theory of end-pumped DPAL, the performances of DPAL using Cs-vapor collisionally broadened by helium are simulated and studied. With the increase of helium pressure, the numerical results show that: 1) the absorption line-width increases and the stimulated absorption cross-section decreases contrarily; 2) the threshold pumping power decreases to minimum and then rolls over to increase linearly; 3) the absorption efficiency rises to maximum initially due to enough large stimulated absorption cross-section in the far wings of collisionally broadened D2 transition (absorption transition), and then begins to reduce; 4) an optimal value of helium pressure exists to obtain the highest output power, leading to an optimal optical-optical efficiency. Furthermore, to generate the self-oscillation of laser, a critical value of helium pressure occurs when small-signal gain equals to the threshold gain.

Recent advances in very large area avalanche photodiodes

NASA Astrophysics Data System (ADS)

Squillante, Michael R.; Christian, James; Entine, Gerald; Farrell, Richard; Karger, Arieh M.; McClish, Mickel; Myers, Richard; Shah, Kanai S.; Taylor, David; Vanderpuye, Kofi; Waer, Peter; Woodring, Mitchell

2003-09-01

The Avalanche Photodiode (APD) is a unique device that combines the advantages of solid state photodetectors with those of high gain devices such as photomultiplier tubes (PMTs). APDs have internal gain that provides a high signal-to-noise ratio. APDs have high quantum efficiency, are fast, compact, and rugged. These properties make them suitable detectors for important applications such as LADAR, detection and identification toxic chemicals and bio-warfare agents, LIDAR fluorescence detection, stand-off laser induced breakdown spectroscopy (LIBS), and nuclear detectors and imagers. Recently there have been significant technical breakthroughs in fabricating very large APDs, APD arrays, and position sensitive APD arrays (PSAPD). Signal gain of over 10,000 has been achieved, single element APDs have been fabricated with active area greater than 40 cm2, monolithic pixelated arrays with up to 28 x 28 elements have been fabricated, and position sensitive APDs have been developed and tested. Additionally, significant progress has been made in improving the fabrication process to provide better uniformity and high yield, permitting cost effective manufacturing of APDs for reduced cost.

The Determinants of the Technical Efficiency of Acute Inpatient Care in Canada.

PubMed

Wang, Li; Grignon, Michel; Perry, Sheril; Chen, Xi-Kuan; Ytsma, Alison; Allin, Sara; Gapanenko, Katerina

2018-04-17

To evaluate the technical efficiency of acute inpatient care at the pan-Canadian level and to explore the factors associated with inefficiency-why hospitals are not on their production frontier. Canadian Management Information System (MIS) database (CMDB) and Discharge Abstract Database (DAD) for the fiscal year of 2012-2013. We use a nonparametric approach (data envelopment analysis) applied to three peer groups (teaching, large, and medium hospitals, focusing on their acute inpatient care only). The double bootstrap procedure (Simar and Wilson 2007) is adopted in the regression. Information on inpatient episodes of care (number and quality of outcomes) was extracted from the DAD. The cost of the inpatient care was extracted from the CMDB. On average, acute hospitals in Canada are operating at about 75 percent efficiency, and this could thus potentially increase their level of outcomes (quantity and quality) by addressing inefficiencies. In some cases, such as for teaching hospitals, the factors significantly correlated with efficiency scores were not related to management but to the social composition of the caseload. In contrast, for large and medium nonteaching hospitals, efficiency related more to the ability to discharge patients to postacute care facilities. The efficiency of medium hospitals is also positively related to treating more clinically noncomplex patients. The main drivers of efficiency of acute inpatient care vary by hospital peer groups. Thus, the results provide different policy and managerial implications for teaching, large, and medium hospitals to achieve efficiency gains. © Health Research and Educational Trust.

Integration and segregation of large-scale brain networks during short-term task automatization

PubMed Central

Mohr, Holger; Wolfensteller, Uta; Betzel, Richard F.; Mišić, Bratislav; Sporns, Olaf; Richiardi, Jonas; Ruge, Hannes

2016-01-01

The human brain is organized into large-scale functional networks that can flexibly reconfigure their connectivity patterns, supporting both rapid adaptive control and long-term learning processes. However, it has remained unclear how short-term network dynamics support the rapid transformation of instructions into fluent behaviour. Comparing fMRI data of a learning sample (N=70) with a control sample (N=67), we find that increasingly efficient task processing during short-term practice is associated with a reorganization of large-scale network interactions. Practice-related efficiency gains are facilitated by enhanced coupling between the cingulo-opercular network and the dorsal attention network. Simultaneously, short-term task automatization is accompanied by decreasing activation of the fronto-parietal network, indicating a release of high-level cognitive control, and a segregation of the default mode network from task-related networks. These findings suggest that short-term task automatization is enabled by the brain's ability to rapidly reconfigure its large-scale network organization involving complementary integration and segregation processes. PMID:27808095

Second generation large area microchannel plate flat panel phototubes

NASA Astrophysics Data System (ADS)

Ertley, C. D.; Siegmund, O. H. W.; Jelinsky, S. R.; Tedesco, J.; Minot, M. J.; O'Mahony, A.; Craven, C. A.; Popecki, M.; Lyashenko, A. V.; Foley, M. R.

2016-07-01

Very large (20 cm × 20 cm) flat panel phototubes are being developed which employ novel microchannel plates (MCPs). The MCPs are manufactured using borosilicate microcapillary arrays which are functionalized by the application of resistive and secondary emissive layers using atomic layer deposition (ALD). This allows the operational parameters to be set by tailoring sequential ALD deposition processes. The borosilicate substrates are robust, including the ability to be produced in large formats (20 cm square). ALD MCPs have performance characteristics (gain, pulse amplitude distributions, and imaging) that are equivalent or better than conventional MCPs. They have low intrinsic background (0.045 events cm-2 sec-1)., high open area ratios (74% for the latest generation of borosilicate substrates), and stable gain during >7 C cm-2 charge extraction after preconditioning (vacuum bake and burn-in). The tube assemblies use a pair of 20 cm × 20 cm ALD MCPs comprised of a borosilicate entrance window, a proximity focused bialkali photocathode, and a strip-line readout anode. The second generation design employs an all glass body with a hot indium seal and a transfer photocathode. We have achieved >20% quantum efficiency and good gain uniformity over the 400 cm2 field of view, spatial resolution of <1 cm and obtained event timing accuracy of close to 100 ps FWHM.

High-efficiency nanostructured silicon solar cells on a large scale realized through the suppression of recombination channels.

PubMed

Zhong, Sihua; Huang, Zengguang; Lin, Xingxing; Zeng, Yang; Ma, Yechi; Shen, Wenzhong

2015-01-21

Nanostructured silicon solar cells show great potential for new-generation photovoltaics due to their ability to approach ideal light-trapping. However, the nanofeatured morphology that brings about the optical benefits also introduces new recombination channels, and severe deterioration in the electrical performance even outweighs the gain in optics in most attempts. This Research News article aims to review the recent progress in the suppression of carrier recombination in silicon nanostructures, with the emphasis on the optimization of surface morphology and controllable nanostructure height and emitter doping concentration, as well as application of dielectric passivation coatings, providing design rules to realize high-efficiency nanostructured silicon solar cells on a large scale. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Practical guidelines for interpreting copy number gains detected by high-resolution array in routine diagnostics

PubMed Central

Hanemaaijer, Nicolien M; Sikkema-Raddatz, Birgit; van der Vries, Gerben; Dijkhuizen, Trijnie; Hordijk, Roel; van Essen, Anthonie J; Veenstra-Knol, Hermine E; Kerstjens-Frederikse, Wilhelmina S; Herkert, Johanna C; Gerkes, Erica H; Leegte, Lamberta K; Kok, Klaas; Sinke, Richard J; van Ravenswaaij-Arts, Conny M A

2012-01-01

The correct interpretation of copy number gains in patients with developmental delay and multiple congenital anomalies is hampered by the large number of copy number variations (CNVs) encountered in healthy individuals. The variable phenotype associated with copy number gains makes interpretation even more difficult. Literature shows that inheritence, size and presence in healthy individuals are commonly used to decide whether a certain copy number gain is pathogenic, but no general consensus has been established. We aimed to develop guidelines for interpreting gains detected by array analysis using array CGH data of 300 patients analysed with the 105K Agilent oligo array in a diagnostic setting. We evaluated the guidelines in a second, independent, cohort of 300 patients. In the first 300 patients 797 gains of four or more adjacent oligonucleotides were observed. Of these, 45.4% were de novo and 54.6% were familial. In total, 94.8% of all de novo gains and 87.1% of all familial gains were concluded to be benign CNVs. Clinically relevant gains ranged from 288 to 7912 kb in size, and were significantly larger than benign gains and gains of unknown clinical relevance (P<0.001). Our study showed that a threshold of 200 kb is acceptable in a clinical setting, whereas heritability does not exclude a pathogenic nature of a gain. Evaluation of the guidelines in the second cohort of 300 patients revealed that the interpretation guidelines were clear, easy to follow and efficient. PMID:21934709

Seasonal photosynthetic gas exchange and water-use efficiency in a constitutive CAM plant, the giant saguaro cactus (Carnegiea gigantea).

PubMed

Bronson, Dustin R; English, Nathan B; Dettman, David L; Williams, David G

2011-11-01

Crassulacean acid metabolism (CAM) and the capacity to store large quantities of water are thought to confer high water use efficiency (WUE) and survival of succulent plants in warm desert environments. Yet the highly variable precipitation, temperature and humidity conditions in these environments likely have unique impacts on underlying processes regulating photosynthetic gas exchange and WUE, limiting our ability to predict growth and survival responses of desert CAM plants to climate change. We monitored net CO(2) assimilation (A(net)), stomatal conductance (g(s)), and transpiration (E) rates periodically over 2 years in a natural population of the giant columnar cactus Carnegiea gigantea (saguaro) near Tucson, Arizona USA to investigate environmental and physiological controls over carbon gain and water loss in this ecologically important plant. We hypothesized that seasonal changes in daily integrated water use efficiency (WUE(day)) in this constitutive CAM species would be driven largely by stomatal regulation of nighttime transpiration and CO(2) uptake responding to shifts in nighttime air temperature and humidity. The lowest WUE(day) occurred during time periods with extreme high and low air vapor pressure deficit (D(a)). The diurnal with the highest D(a) had low WUE(day) due to minimal net carbon gain across the 24 h period. Low WUE(day) was also observed under conditions of low D(a); however, it was due to significant transpiration losses. Gas exchange measurements on potted saguaro plants exposed to experimental changes in D(a) confirmed the relationship between D(a) and g(s). Our results suggest that climatic changes involving shifts in air temperature and humidity will have large impacts on the water and carbon economy of the giant saguaro and potentially other succulent CAM plants of warm desert environments.

Impact of Energy Gain and Subsystem Characteristics on Fusion Propulsion Performance Balances

NASA Technical Reports Server (NTRS)

Chakrabarti, Suman; Schmidt, George R.

2000-01-01

Rapid transportation of large payloads and human crews to destinations throughout the solar system will require propulsion systems having not only very high exhaust velocities (I (sub sp) greater than or equal to 10 (exp 4) to 10 (exp 5) sec) but also extremely low mass-power ratios (alpha less than or equal to 10 (exp -1) kg/kW). Such low a are difficult to achieve with power-limited propulsion systems. but may be attainable with fusion and other high I (sub SP) nuclear concepts that produce energy within the propellant. The magnitude of this energy gain is of fundamental importance. It must be large enough to sustain the nuclear process while still providing a high jet power relative to the massive power-intensive subsystems associated with these types of concepts. This paper evaluates the energy gain and mass-power characteristics required for a consistent with 1-year roundtrip planetary missions ranging up to 100 AU. Central to this analysis is an equation for overall system a, which is derived from the power balance of a generalized "gain-limited" propulsion system. Results show that the gain required to achieve alpha approximately 10 (exp -1) kg/kW with foreseeable subsystem technology can vary from 50 to as high as 10,000, which is 2 to 5 orders of magnitude greater than current state-of-the art. However, order of magnitude improvements in propulsion subsystem mass and efficiency could reduce gain requirements to 10 to 1,000 - still a very challenging goal.

Utilizing fast multipole expansions for efficient and accurate quantum-classical molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Schwörer, Magnus; Lorenzen, Konstantin; Mathias, Gerald; Tavan, Paul

2015-03-01

Recently, a novel approach to hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations has been suggested [Schwörer et al., J. Chem. Phys. 138, 244103 (2013)]. Here, the forces acting on the atoms are calculated by grid-based density functional theory (DFT) for a solute molecule and by a polarizable molecular mechanics (PMM) force field for a large solvent environment composed of several 103-105 molecules as negative gradients of a DFT/PMM hybrid Hamiltonian. The electrostatic interactions are efficiently described by a hierarchical fast multipole method (FMM). Adopting recent progress of this FMM technique [Lorenzen et al., J. Chem. Theory Comput. 10, 3244 (2014)], which particularly entails a strictly linear scaling of the computational effort with the system size, and adapting this revised FMM approach to the computation of the interactions between the DFT and PMM fragments of a simulation system, here, we show how one can further enhance the efficiency and accuracy of such DFT/PMM-MD simulations. The resulting gain of total performance, as measured for alanine dipeptide (DFT) embedded in water (PMM) by the product of the gains in efficiency and accuracy, amounts to about one order of magnitude. We also demonstrate that the jointly parallelized implementation of the DFT and PMM-MD parts of the computation enables the efficient use of high-performance computing systems. The associated software is available online.

BLESS 2: accurate, memory-efficient and fast error correction method.

PubMed

Heo, Yun; Ramachandran, Anand; Hwu, Wen-Mei; Ma, Jian; Chen, Deming

2016-08-01

The most important features of error correction tools for sequencing data are accuracy, memory efficiency and fast runtime. The previous version of BLESS was highly memory-efficient and accurate, but it was too slow to handle reads from large genomes. We have developed a new version of BLESS to improve runtime and accuracy while maintaining a small memory usage. The new version, called BLESS 2, has an error correction algorithm that is more accurate than BLESS, and the algorithm has been parallelized using hybrid MPI and OpenMP programming. BLESS 2 was compared with five top-performing tools, and it was found to be the fastest when it was executed on two computing nodes using MPI, with each node containing twelve cores. Also, BLESS 2 showed at least 11% higher gain while retaining the memory efficiency of the previous version for large genomes. Freely available at https://sourceforge.net/projects/bless-ec dchen@illinois.edu Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

How efficient are New Zealand's District Health Boards at producing life expectancy gains for Māori and Europeans?

PubMed

Sandiford, Peter; Consuelo, David Juan José Vivas; Rouse, Paul

2017-04-01

Use data envelopment analysis (DEA) to measure the efficiency of New Zealand's District Health Boards (DHBs) at achieving gains in Māori and European life expectancy (LE). Using life tables for 2006 and 2013, a two-output DEA model established the production possibility frontier for Māori and European LE gain. Confidence limits were generated from a 10,000 replicate Monte Carlo simulation. Results support the use of LE change as an indicator of DHB efficiency. DHB mean income and education were related to initial LE but not to its rate of change. LE gains were unrelated to either the initial level of life expectancy or to the proportion of Māori in the population. DHB efficiency ranged from 79% to 100%. Efficiency was significantly correlated with DHB financial performance. Changes in LE did not depend on the social characteristics of the DHB. The statistically significant association between efficiency and financial performance supports its use as an indicator of managerial effectiveness. Implications for public health: Efficient health systems achieve better population health outcomes. DEA can be used to measure the relative efficiency of sub-national health authorities at achieving health gain and equity outcomes. © 2016 The Authors.

Numerical investigation of output beam quality in efficient broadband optical parametric chirped pulse amplification

NASA Astrophysics Data System (ADS)

Liu, Xiao-Di; Xu, Lu; Liang, Xiao-Yan

2017-01-01

We theoretically analyzed output beam quality of broad bandwidth non-collinear optical parametric chirped pulse amplification (NOPCPA) in LiB3O5 (LBO) centered at 800 nm. With a three-dimensional numerical model, the influence of the pump intensity, pump and signal spatial modulations, and the walk-off effect on the OPCPA output beam quality are presented, together with conversion efficiency and the gain spectrum. The pump modulation is a dominant factor that affects the output beam quality. Comparatively, the influence of signal modulation is insignificant. For a low-energy system with small beam sizes, walk-off effect has to be considered. Pump modulation and walk-off effect lead to asymmetric output beam profile with increased modulation. A special pump modulation type is found to optimize output beam quality and efficiency. For a high-energy system with large beam sizes, the walk-off effect can be neglected, certain back conversion is beneficial to reduce the output modulation. A trade-off must be made between the output beam quality and the conversion efficiency, especially when the pump modulation is large since. A relatively high conversion efficiency and a low output modulation are both achievable by controlling the pump modulation and intensity.

Highly nonplanar lifting systems

NASA Technical Reports Server (NTRS)

Kroo, Ilan; McMasters, John; Smith, Stephen C.

1996-01-01

This paper deals with nonplanar wing concepts -- their advantages and possible applications in a variety of aircraft designs. A brief review and assessment of several concepts from winglets to ring wings is followed by a more detailed look at two recent ideas: exploiting nonplanar wakes to reduce induced drag, and applying a 'C-wing' design to large commercial transports. Results suggest that potential efficiency gains may be significant, while several nonaerodynamic characteristics are particularly interesting.

Electromagnetic Counter-Counter Measure (ECCM) Techniques of the Digital Microwave Radio.

DTIC Science & Technology

1982-05-01

Frequency hopping requires special synthesizers and filter banks. Large bandwidth expansion in a microwave radio relay application can best be achieved with...34 processing gain " performance as a function of jammer modulation type " pulse jammer performance • emission bandwidth and spectral shaping 0... spectral efficiency, implementation complexity, and suitability for ECCK techniques will be considered. A sumary of the requirements and characteristics of

In-situ Roll-to-Roll Printing of Highly Efficient Organic Solar Cells

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

Bao, Zhenan; Toney, Michael; Clancy, Paulette

2016-05-30

This project focuses on developing a roll-to-roll printing setup for organic solar cells with the capability to follow the film formation in situ with small and wide angle X-ray scattering, and to improve the performance of printed organic solar cells. We demonstrated the use of the printing setup to capture important aspects of existing industrial printing methods, which ensures that the solar cell performance achieved in our printing experiments would be largely retained in an industrial fabrication process. We employed both known and newly synthesized polymers as the donor and acceptor materials, and we studied the morphological changes in realmore » time during the printing process by X-ray scattering. Our experimental efforts are also accompanied by theoretical modeling of both the fluid dynamic aspects of the printing process and the nucleation and crystallization kinetics during the film formation. The combined insight into the printing process gained from the research provides a detailed understanding of the factors governing the printed solar cell’s performance. Finally using the knowledge we gained, we demonstrated large area ( > 10 cm2) printed organic solar cells with more than 5 percent power conversion efficiency, which is best achieved performance for roll-to-roll printed organic solar cells.« less

Dissociation phenomena in electron-beam sustained carbon dioxide lasers

NASA Technical Reports Server (NTRS)

Harris, Michael R.; Willetts, David V.

1990-01-01

A number of applications are emerging requiring efficient, long pulse, long-life sealed CO2 lasers. Examples include the proposed NASA and ESA wind lidars. Electron-beam sustained discharge devices are strong contenders. Unlike self-sustained discharges, e-beam sustenance readily provides efficient performance from large volume discharges and offers pulse lengths well in excess of the microsecond or so generally associated with self-sustained devices. In the case of the e-beam sustained laser, since the plasma is externally maintained and operated at electric field strengths less than that associated with the glow to arc transition, the discharges can be run even in the presence of strongly attacking species such as O2. Build up of large levels of attacking contaminants is nevertheless undesirable as their presence reduces the current drawn by the plasma and thus the pumping rate to the upper laser level. The impedance rise leads to a mismatch of the pulse forming network with a consequent loss of control over energy deposition, operating E/N, and gain. Clearly CO2 dissociation rates, the influence of dissociation products on the discharge and gain, and tolerance of the discharge to these products need to be determined. This information can then be used to assess co-oxidation catalyst requirements for sealed operation.

Reducing runoff and nutrient loss from agricultural land in the Lower Mississippi River Basin

NASA Astrophysics Data System (ADS)

Reba, M. L.; Bouldin, J.; Teague, T.; Choate, J.

2011-12-01

The Lower Mississippi River Basin (LMRB) yields suspended sediment, total phosphorus, total nitrogen and silicate that are disproportionately high for the area. In addition, groundwater pumping of the alluvial aquifer has been deemed unsustainable under current practices. Much of the LMRB is used for large-scale agricultural production of primarily cotton, soybeans and rice. The incorporation of conservation practices may improve nutrient use efficiency and reduce runoff from agricultural fields. Three paired fields have been instrumented at the edge-of-field to quantify nutrients and runoff. The fields are located in northeastern Arkansas in the Little River Ditches and St. Francis watersheds. Nutrient use efficiency will be gained by utilizing variable rate fertilizer application technology. Reduced runoff will be gained through improved irrigation management. This study quantifies the runoff and nutrient loss from the first year of a 5-year study and will serve as a baseline for a comparative study of conservation practices employed on the paired fields.

Vortex spin-torque oscillator stabilized by phase locked loop using integrated circuits

NASA Astrophysics Data System (ADS)

Kreissig, Martin; Lebrun, R.; Protze, F.; Merazzo-Jaimes, K.; Hem, J.; Vila, L.; Ferreira, R.; Cyrille, M.-C.; Ellinger, F.; Cros, V.; Ebels, U.; Bortolotti, P.

2017-05-01

Spin-torque nano-oscillators (STO) are candidates for the next technological implementation of spintronic devices in commercial electronic systems. For use in microwave applications, improving the noise figures by efficient control of their phase dynamics is a mandatory requirement. In order to achieve this, we developed a compact phase locked loop (PLL) based on custom integrated circuits (ICs) and demonstrate that it represents an efficient way to reduce the phase noise level of a vortex based STO. The advantage of our approach to phase stabilize STOs is that our compact system is highly reconfigurable e.g. in terms of the frequency divider ratio N, RF gain and loop gain. This makes it robust against device to device variations and at the same time compatible with a large range of STOs. Moreover, by taking advantage of the natural highly non-isochronous nature of the STO, the STO frequency can be easily controlled by e.g. changing the divider ratio N.

Comparison of Seven Methods for Boolean Factor Analysis and Their Evaluation by Information Gain.

PubMed

Frolov, Alexander A; Húsek, Dušan; Polyakov, Pavel Yu

2016-03-01

An usual task in large data set analysis is searching for an appropriate data representation in a space of fewer dimensions. One of the most efficient methods to solve this task is factor analysis. In this paper, we compare seven methods for Boolean factor analysis (BFA) in solving the so-called bars problem (BP), which is a BFA benchmark. The performance of the methods is evaluated by means of information gain. Study of the results obtained in solving BP of different levels of complexity has allowed us to reveal strengths and weaknesses of these methods. It is shown that the Likelihood maximization Attractor Neural Network with Increasing Activity (LANNIA) is the most efficient BFA method in solving BP in many cases. Efficacy of the LANNIA method is also shown, when applied to the real data from the Kyoto Encyclopedia of Genes and Genomes database, which contains full genome sequencing for 1368 organisms, and to text data set R52 (from Reuters 21578) typically used for label categorization.

Highly efficient pseudomorphic InGaAs/GaAs/AlGaAs single quantum well lasers for monolithic integration

NASA Technical Reports Server (NTRS)

Larsson, A.; Cody, J.; Forouhar, S.; Lang, R. J.

1990-01-01

Highly efficient ridge waveguide pseudomorphic single quantum well lasers, emitting at 980 nm, have been fabricated from an In(0.2)Ga(0.8)As/GaAs/AlGaAs graded-index separate confinement heterostructure grown by molecular beam epitaxy. The laterial index guiding provided by the ridge reduces the anomalously large lateral loss of optical power found in gain-guided structures, thereby reducing the internal loss by more than 50 percent. The low threshold current (7.6 mA) and high differential quantum efficiency (79 percent) obtained under continuous operation as well as the transparency of the GaAs substrate to the emitted radiation render these lasers attractive for Ga-As-based optoelectronic integration.

Simple formalism for efficient derivatives and multi-determinant expansions in quantum Monte Carlo

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

Filippi, Claudia, E-mail: c.filippi@utwente.nl; Assaraf, Roland, E-mail: assaraf@lct.jussieu.fr; Moroni, Saverio, E-mail: moroni@democritos.it

2016-05-21

We present a simple and general formalism to compute efficiently the derivatives of a multi-determinant Jastrow-Slater wave function, the local energy, the interatomic forces, and similar quantities needed in quantum Monte Carlo. Through a straightforward manipulation of matrices evaluated on the occupied and virtual orbitals, we obtain an efficiency equivalent to algorithmic differentiation in the computation of the interatomic forces and the optimization of the orbital parameters. Furthermore, for a large multi-determinant expansion, the significant computational gain afforded by a recently introduced table method is here extended to the local value of any one-body operator and to its derivatives, inmore » both all-electron and pseudopotential calculations.« less

Electric Current Flow Through Two-Dimensional Networks

NASA Astrophysics Data System (ADS)

Gaspard, Mallory

In modern nanotechnology, two-dimensional atomic network structures boast promising applications as nanoscale circuit boards to serve as the building blocks of more sustainable and efficient, electronic devices. However, properties associated with the network connectivity can be beneficial or deleterious to the current flow. Taking a computational approach, we will study large uniform networks, as well as large random networks using Kirchhoff's Equations in conjunction with graph theoretical measures of network connectedness and flows, to understand how network connectivity affects overall ability for successful current flow throughout a network. By understanding how connectedness affects flow, we may develop new ways to design more efficient two-dimensional materials for the next generation of nanoscale electronic devices, and we will gain a deeper insight into the intricate balance between order and chaos in the universe. Rensselaer Polytechnic Institute, SURP Institutional Grant.

ATLAS and LHC computing on CRAY

NASA Astrophysics Data System (ADS)

Sciacca, F. G.; Haug, S.; ATLAS Collaboration

2017-10-01

Access and exploitation of large scale computing resources, such as those offered by general purpose HPC centres, is one important measure for ATLAS and the other Large Hadron Collider experiments in order to meet the challenge posed by the full exploitation of the future data within the constraints of flat budgets. We report on the effort of moving the Swiss WLCG T2 computing, serving ATLAS, CMS and LHCb, from a dedicated cluster to the large Cray systems at the Swiss National Supercomputing Centre CSCS. These systems do not only offer very efficient hardware, cooling and highly competent operators, but also have large backfill potentials due to size and multidisciplinary usage and potential gains due to economy at scale. Technical solutions, performance, expected return and future plans are discussed.

An efficient fast response and high-gain solar-blind flexible ultraviolet photodetector employing hybrid geometry

NASA Astrophysics Data System (ADS)

Hussain, Amreen A.; Pal, Arup R.; Patil, Dinkar S.

2014-05-01

We report high performance flexible hybrid ultraviolet photodetector with solar-blind sensitivity using nanocomposite film of plasma polymerized aniline-titanium dioxide. A facile solvent-free plasma technique is used to synthesize superior quality hybrid material with high yield. The hybrid photodetector exhibited high photoconductive gain of the order of ˜105 and fast speed with response and recovery time of 22.87 ms and 34.23 ms. This is an excellent result towards getting a balance in the response speed and photoconductive gain trade-off of the photodetectors reported so far. In addition, the device has the advantages of enhanced photosensitivity ((Ilight - Idark)/Idark) of the order of ˜102 and high responsivity of ˜104 AW-1. All the merits substantiates that, to prepare hybrid material, plasma based method holds potential to be an easy way for realizing large scale nanostructured photodetectors for practical applications.

Microchannel plate fabrication using glass capillary arrays with Atomic Layer Deposition films for resistance and gain

NASA Astrophysics Data System (ADS)

Popecki, M. A.; Adams, B.; Craven, C. A.; Cremer, T.; Foley, M. R.; Lyashenko, A.; O'Mahony, A.; Minot, M. J.; Aviles, M.; Bond, J. L.; Stochaj, M. E.; Worstell, W.; Elam, J. W.; Mane, A. U.; Siegmund, O. H. W.; Ertley, C.; Kistler, L. M.; Granoff, M. S.

2016-08-01

Microchannel plates (MCPs) have been used for many years in space flight instrumentation as fast, lightweight electron multipliers. A new MCP fabrication method combines a glass substrate composed of hollow glass capillary arrays with thin film coatings to provide the resistive and secondary electron emissive properties. Using this technique, the gain, resistance, and glass properties may be chosen independently. Large-area MCPs are available at moderate cost. Secondary emission films of Al2O3 and MgO provide sustained high gain as charge is extracted from the MCP. Long lifetimes are possible, and a total extracted charge of 7 C/cm2 has been demonstrated. Background rates are low because the glass substrate has little radioactive potassium 40. Curved MCPs are easily fabricated with this technique to suit instrument symmetries, simplifying secondary electron steering and smoothing azimuthal efficiency.

Pilot Production of Large Area Microchannel Plates and Picosecond Photodetectors

NASA Astrophysics Data System (ADS)

Minot, M.; Adams, B.; Abiles, M.; Bond, J.; Craven, C.; Cremer, T.; Foley, M.; Lyashenko, A.; Popecki, M.; Stochaj, M.; Worstell, W.; Elam, J.; Mane, A.; Siegmund, O.; Ertley, C.

2016-09-01

Pilot production performance is reported for large area atomic layer deposition (ALD) coated microchannel plates (ALD-GCA-MCPs) and for Large Area Picosecond Photodetectors (LAPPD™) which incorporate them. "Hollowcore" glass capillary array (GCA) substrates are coated with ALD resistive and emissive layers to form the ALDGCA- MCPs, an approach that facilitates independent selection of glass substrates that are mechanically stronger and that have lower levels of radioactive alkali elements compared to conventional MCP lead glass, reducing background noise[1,2,3,4]. ALD-GCA-MCPs have competitive gain ( 104 each or 107 for a chevron pair ), enhanced lifetime and gain stability (7 C cm-2 of charge extraction), reduced background levels (0.028 events cm-2 sec-1) and low gamma-ray detection efficiency. They can be fabricated in large area (20cm X 20 cm) planar and curved formats suitable for use in high radiation environment applications, including astronomy, space instrumentation, and remote night time sensing. The LAPPD™ photodetector incorporates these ALD-GCA-MCPs in an all-glass hermetic package with top and bottom plates and sidewalls made of borosilicate float glass. Signals are generated by a bi-alkali Na2KSb photocathode, amplified with a stacked chevron pair of ALD-GCA-MCPs. Signals are collected on RF strip-line anodes integrated into to the bottom plates which exit the detector via pin-free hermetic seals under the side walls [5]. Tests show that LAPPDTMs have electron gains greater than 107, submillimeter spatial resolution for large (multiphoton) pulses and several mm for single photons, time resolution less than 50 picoseconds for single photons, predicted resolution less than 5 picoseconds for large pulses, high stability versus charge extraction[6], and good uniformity for applications including astrophysics, neutron detection, high energy physics Cherenkov light detection, and quantum-optical photon-correlation experiments.

Investigation of large format microchannel plate Z configurations

NASA Technical Reports Server (NTRS)

Siegmund, O. H. W.; Coburn, K.; Malina, R. F.

1985-01-01

The performance of triplet (Z) stacks of microchannel plates (MCPs) has been studied as a part of the instrument development for the Extreme Ultraviolet Explorer (EUVE) satellite mission. Relatively large MCPs with a 60-mm diameter and having a large 80:1 channel length to diameter (L:D) ratio were used in several configurations. The MCPs were used in the EUVE prototype imaging detector to provide more than 512 x 512 pixels with low image distortion (less than 1 percent). The gain and pulse height characteristics of the MCPs were examined, showing that both high gains (more than 2 x 10 to the 7th) and tight output pulse height distributions (less than 30 percent FWHM) may be achieved. Simple distribution techniques have also allowed low intrinsic background event rates (less than 0.15 events per sq cm/s) to be obtained. Variation of the quantum efficiency of the MCPs over the wavelength range 160-1216 A has been investigated for a range of angles of incidence. The effect of temperature variations on MCP operating characteristics has also been evaluated.

Extended interaction oversized coaxial relativistic klystron amplifier with gigawatt-level output at Ka band

NASA Astrophysics Data System (ADS)

Li, Shifeng; Duan, Zhaoyun; Huang, Hua; Liu, Zhenbang; He, Hu; Wang, Fei; Wang, Zhanliang; Gong, Yubin

2018-04-01

In this paper, an extended interaction oversized coaxial relativistic klystron amplifier (EIOC-RKA) with Gigawatt-level output at Ka band is proposed. We introduce the oversized coaxial and multi-gap resonant cavities to increase the power capacity and investigate a non-uniform extended interaction output cavity to improve the electronic efficiency of the EIOC-RKA. We develop a high order mode gap in the input and output cavities to easily design and fabricate the input and output couplers. Meanwhile, we design the EIOC-RKA by using the particle-in-cell simulation. In the simulations, we use an electron beam with a current of 6 kA and a voltage of 525 kV, which is focused by a low focusing magnetic flux intensity of 0.5 T. The simulation results demonstrate that the saturated output power is 1.17 GW, the electronic efficiency is 37.1%, and the saturated gain is 57 dB at 30 GHz. The self-oscillation is suppressed by adopting the absorbing materials. The proposed EIOC-RKA has plenty of advantages such as large power capacity, high electronic efficiency, low focusing magnetic, high gain, and simple structure.

A comparison of the Cray-2 performance before and after the installation of memory pseudo-banking

NASA Technical Reports Server (NTRS)

Schmickley, Ronald D.; Bailey, David H.

1987-01-01

A suite of 13 large Fortran benchmark codes were run on a Cray-2 configured with memory pseudo-banking circuits, and floating point operation rates were measured for each under a variety of system load configurations. These were compared with similar flop measurements taken on the same system before installation of the pseudo-banking. A useful memory access efficiency parameter was defined and calculated for both sets of performance rates, allowing a crude quantitative measure of the improvement in efficiency due to pseudo-banking. Programs were categorized as either highly scalar (S) or highly vectorized (V) and either memory-intensive or register-intensive, giving 4 categories: S-memory, S-register, V-memory, and V-register. Using flop rates as a simple quantifier of these 4 categories, a scatter plot of efficiency gain vs Mflops roughly illustrates the improvement in floating point processing speed due to pseudo-banking. On the Cray-2 system tested this improvement ranged from 1 percent for S-memory codes to about 12 percent for V-memory codes. No significant gains were made for V-register codes, which was to be expected.

Efficient traffic grooming with dynamic ONU grouping for multiple-OLT-based access network

NASA Astrophysics Data System (ADS)

Zhang, Shizong; Gu, Rentao; Ji, Yuefeng; Wang, Hongxiang

2015-12-01

Fast bandwidth growth urges large-scale high-density access scenarios, where the multiple Passive Optical Networking (PON) system clustered deployment can be adopted as an appropriate solution to fulfill the huge bandwidth demands, especially for a future 5G mobile network. However, the lack of interaction between different optical line terminals (OLTs) results in part of the bandwidth resources waste. To increase the bandwidth efficiency, as well as reduce bandwidth pressure at the edge of a network, we propose a centralized flexible PON architecture based on Time- and Wavelength-Division Multiplexing PON (TWDM PON). It can provide flexible affiliation for optical network units (ONUs) and different OLTs to support access network traffic localization. Specifically, a dynamic ONU grouping algorithm (DGA) is provided to obtain the minimal OLT outbound traffic. Simulation results show that DGA obtains an average 25.23% traffic gain increment under different OLT numbers within a small ONU number situation, and the traffic gain will increase dramatically with the increment of the ONU number. As the DGA can be deployed easily as an application running above the centralized control plane, the proposed architecture can be helpful to improve the network efficiency for future traffic-intensive access scenarios.

Diode amplifier of modulated optical beam power

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

D'yachkov, N V; Bogatov, A P; Gushchik, T I

2014-11-30

Analytical relations are obtained between characteristics of modulated light at the output and input of an optical diode power amplifier operating in the highly saturated gain regime. It is shown that a diode amplifier may act as an amplitude-to-phase modulation converter with a rather large bandwidth (∼10 GHz). The low sensitivity of the output power of the amplifier to the input beam power and its high energy efficiency allow it to be used as a building block of a high-power multielement laser system with coherent summation of a large number of optical beams. (lasers)

A method for exponential propagation of large systems of stiff nonlinear differential equations

NASA Technical Reports Server (NTRS)

Friesner, Richard A.; Tuckerman, Laurette S.; Dornblaser, Bright C.; Russo, Thomas V.

1989-01-01

A new time integrator for large, stiff systems of linear and nonlinear coupled differential equations is described. For linear systems, the method consists of forming a small (5-15-term) Krylov space using the Jacobian of the system and carrying out exact exponential propagation within this space. Nonlinear corrections are incorporated via a convolution integral formalism; the integral is evaluated via approximate Krylov methods as well. Gains in efficiency ranging from factors of 2 to 30 are demonstrated for several test problems as compared to a forward Euler scheme and to the integration package LSODE.

Measuring the efficiency of large pharmaceutical companies: an industry analysis.

PubMed

Gascón, Fernando; Lozano, Jesús; Ponte, Borja; de la Fuente, David

2017-06-01

This paper evaluates the relative efficiency of a sample of 37 large pharmaceutical laboratories in the period 2008-2013 using a data envelopment analysis (DEA) approach. We describe in detail the procedure followed to select and construct relevant inputs and outputs that characterize the production and innovation activity of these pharmaceutical firms. Models are estimated with financial information from Datastream, including R&D investment, and the number of new drugs authorized by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) considering the time effect. The relative performances of these firms-taking into consideration the strategic importance of R&D-suggest that the pharmaceutical industry is a highly competitive sector given that there are many laboratories at the efficient frontier and many inefficient laboratories close to this border. Additionally, we use data from S&P Capital IQ to analyze 2071 financial transactions announced by our sample of laboratories as an alternative way to gain access to new drugs, and we link these transactions with R&D investment and DEA efficiency. We find that efficient laboratories make on average more financial transactions, and the relative size of each transaction is larger. However, pharmaceutical companies that simultaneously are more efficient and invest more internally in R&D announce smaller transactions relative to total assets.

Multi-state lasing in self-assembled ring-shaped green fluorescent protein microcavities

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

Dietrich, Christof P., E-mail: cpd3@st-andrews.ac.uk; Höfling, Sven; Gather, Malte C., E-mail: mcg6@st-andrews.ac.uk

2014-12-08

We demonstrate highly efficient lasing from multiple photonic states in microcavities filled with self-assembled rings of recombinant enhanced green fluorescent protein (eGFP) in its solid state form. The lasing regime is achieved at very low excitation energies of 13 nJ and occurs from cavity modes dispersed in both energy and momentum. We attribute the momentum distribution to very efficient scattering of incident light at the surface of the eGFP rings. The distribution of lasing states in energy is induced by the large spectral width of the gain spectrum of recombinant eGFP (FWHM ≅ 25 nm)

Feed efficiency and the microbiota of the alimentary tract

USDA-ARS?s Scientific Manuscript database

There is considerable variation in the efficiency that cattle convert feed for maintenance and product (body weight gain, milk, and conceptus). Both intake and gain are polygenic traits and to better understand factors that contribute to variation in feed efficiency more defined phenotypes are need...

Room-temperature electron spin amplifier based on Ga(In)NAs alloys.

PubMed

Puttisong, Yuttapoom; Buyanova, Irina A; Ptak, Aaron J; Tu, Charles W; Geelhaar, Lutz; Riechert, Henning; Chen, Weimin M

2013-02-06

The first experimental demonstration of a spin amplifier at room temperature is presented. An efficient, defect-enabled spin amplifier based on a non-magnetic semiconductor, Ga(In)NAs, is proposed and demonstrated, with a large spin gain (up to 2700% at zero field) for conduction electrons and a high cut-off frequency of up to 1 GHz. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance Evaluation of Solar Blind NLOS Ultraviolet Communication Systems

DTIC Science & Technology

2008-12-01

noise and signal count statistical distributions . Then we further link key system parameters such as path loss and communication bit error rate (BER... quantum noise limited photon-counting detection. These benefits can now begin to be realized based on technological advances in both miniaturized...multiplication gain of 105~107, high responsivity of 62 A/W, large detection area of a few cm2, reasonable quantum efficiency of 15%, and low dark current

A new and efficient theoretical model to analyze chirped grating distributed feedback lasers

NASA Astrophysics Data System (ADS)

Arif, Muhammad

Threshold conditions of a distributed feedback (DFB) laser with a linearly chirped grating are investigated using a new and efficient method. DFB laser with chirped grating is found to have significant effects on the lasing characteristics. The coupled wave equations for these lasers are derived and solved using a power series method to obtain the threshold condition. A Newton- Raphson routine is used to solve the threshold conditions numerically to obtain threshold gain and lasing wavelengths. To prove the validity of this model, it is applied to both conventional index-coupled and complex- coupled DFB lasers. The threshold gain margins are calculated as functions of the ratio of the gain coupling to index coupling (|κg|/|κ n|), and the phase difference between the index and gain gratings. It was found that for coupling coefficient |κ|l < 0.9, the laser shows a mode degeneracy at particular values of the ratio |κ g|/|κn|, for cleaved facets. We found that at phase differences π/2 and 3π/2, between the gain and index grating, for an AR-coated complex-coupled laser, the laser becomes multimode and a different mode starts to lase. We also studied the effect of the facet reflectivity (both magnitude and phase) on the gain margin of a complex- coupled DFB laser. Although, the gain margin varies slowly with the magnitude of the facet reflectivity, it shows large variations as a function of the phase. Spatial hole burning was found to be minimum at phase difference nπ, n = 0, 1, ... and maximum at phase differences π/2 and 3π/2. The single mode gain margin of an index-coupled linearly chirped CG-DFB is calculated for different chirping factors and coupling constants. We found that there is clearly an optimum chirping for which the single mode gain margin is maximum. The gain margins were calculated also for different positions of the cavity center. The effect of the facet reflectivities and their phases on the gain margin was investigated. We found the gain margin is maximum and the Spatial Hole Burning (SHB) is minimum for the cavity center at the middle of the laser cavity. Effect of chirping on the threshold gain, gain margin and spatial hole burning (SHB) for different parameters, such as the coupling coefficients, facet reflectivities, etc., of these lasers are studied. Single mode yield of these lasers are calculated and compared with that of a uniform grating DFB laser.

Photoexcited escape probability, optical gain, and noise in quantum well infrared photodetectors

NASA Technical Reports Server (NTRS)

Levine, B. F.; Zussman, A.; Gunapala, S. D.; Asom, M. T.; Kuo, J. M.; Hobson, W. S.

1992-01-01

We present a detailed and thorough study of a wide variety of quantum well infrared photodetectors (QWIPs), which were chosen to have large differences in their optical and transport properties. Both n- and p-doped QWIPs, as well as intersubband transitions based on photoexcitation from bound-to-bound, bound-to-quasi-continuum, and bound-to-continuum quantum well states were investigated. The measurements and theoretical analysis included optical absorption, responsivity, dark current, current noise, optical gain, hot carrier mean free path; net quantum efficiency, quantum well escape probability, quantum well escape time, as well as detectivity. These results allow a better understanding of the optical and transport physics and thus a better optimization of the QWIP performance.

Quality control for the first large areas of triple-GEM chambers for the CMS endcaps

NASA Astrophysics Data System (ADS)

Abbaneo, D.; Abbas, M.; Abbrescia, M.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Aleksandrov, A.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F. R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M. M.; De Lentdecker, G.; De Oliveira, R.; de Robertis, G.; Dildick, S.; Dorney, B.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R. M.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y. G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P. K.; Mandal, K.; Marchioro, A.; Marinov, A.; Majumdar, N.; Merlin, J. A.; Mitselmakher, G.; Mohanty, A. K.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L. M.; Paolucci, P.; Park, I.; Passeggio, G.; Pavlov, B.; Philipps, B.; Piccolo, D.; Postema, H.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Ryu, G.; Ryu, M. S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A. H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S. K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

2018-02-01

The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC. This project is at the final stages of R&D and moving to production. An unprecedented large area of several 100 m2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector. The quality control steps will include optical inspection, cleaning and baking of all materials and parts used to build the detector, leakage current tests of the GEM foils, high voltage tests, gas leak tests of the chambers and monitoring pressure drop vs. time, gain calibration to know the optimal operation region of the detector, gain uniformity tests, and studying the efficiency, noise and tracking performance of the detectors in a cosmic stand using scintillators.

1.5-μm high-average power laser amplifier using a Er,Yb:glass planar waveguide for coherent Doppler lidar

NASA Astrophysics Data System (ADS)

Sakimura, Takeshi; Watanabe, Yojiro; Ando, Toshiyuki; Kameyama, Shumpei; Asaka, Kimio; Tanaka, Hisamichi; Yanagisawa, Takayuki; Hirano, Yoshihito; Inokuchi, Hamaki

2012-11-01

We have developed a 1.5-μm eye-safe wavelength high average power laser amplifier using an Er,Yb:glass planar waveguide for coherent Doppler LIDAR. Large cooling surface of the planar waveguide enabled high average power pumping for Er,Yb:glass which has low thermal fracture limit. Nonlinear effects are suppressed by the large beam size which is designed by the waveguide thickness and the beam width of the planar direction. Multi-bounce optical path configuration and high-intensity pumping provide high-gain and high-efficient operation using three-level laser material. With pulsed operation, the maximum pulse energy of 1.9 mJ was achieved at the repetition rate of 4 kHz. Output average power of the amplified signal was 7.6W with the amplified gain of more than 20dB. This amplifier is suitable for coherent Doppler LIDAR to enhance the measurable range.

Gain and Polarization Properties of a Large Radio Telescope from Calculation and Measurement: The John A. Galt Telescope

NASA Astrophysics Data System (ADS)

Du, X.; Landecker, T. L.; Robishaw, T.; Gray, A. D.; Douglas, K. A.; Wolleben, M.

2016-11-01

Measurement of the brightness temperature of extended radio emission demands knowledge of the gain (or aperture efficiency) of the telescope and measurement of the polarized component of the emission requires correction for the conversion of unpolarized emission from sky and ground to apparently polarized signal. Radiation properties of the John A. Galt Telescope at the Dominion Radio Astrophysical Observatory were studied through analysis and measurement in order to provide absolute calibration of a survey of polarized emission from the entire northern sky from 1280 to 1750 MHz, and to understand the polarization performance of the telescope. Electromagnetic simulation packages CST and GRASP-10 were used to compute complete radiation patterns of the telescope in all Stokes parameters, and thereby to establish gain and aperture efficiency. Aperture efficiency was also evaluated using geometrical optics and ray tracing analysis and was measured based on the known flux density of Cyg A. Measured aperture efficiency varied smoothly with frequency between values of 0.49 and 0.54; GRASP-10 yielded values 6.5% higher but with closely similar variation with frequency. Overall error across the frequency band is 3%, but values at any two frequencies are relatively correct to ˜1%. Dominant influences on aperture efficiency are the illumination taper of the feed radiation pattern and the shadowing of the reflector from the feed by the feed-support struts. A model of emission from the ground was developed based on measurements and on empirical data obtained from remote sensing of the Earth from satellite-borne telescopes. This model was convolved with the computed antenna response to estimate conversion of ground emission into spurious polarized signal. The computed spurious signal is comparable to measured values, but is not accurate enough to be used to correct observations. A simpler model, in which the ground is considered as an unpolarized emitter with a brightness temperature of ˜240 K, is shown to have useful accuracy when compared to measurements.

Relationship among performance, carcass, and feed efficiency characteristics, and their ability to predict economic value in the feedlot.

PubMed

Retallick, K M; Faulkner, D B; Rodriguez-Zas, S L; Nkrumah, J D; Shike, D W

2013-12-01

A 4-yr study was conducted using 736 steers of known Angus, Simmental, or Simmental × Angus genetics to determine performance, carcass, and feed efficiency factors that explained variation in economic performance. Steers were pen fed and individual DMI was recorded using a GrowSafe automated feeding system (GrowSafe Systems Ltd., Airdrie, Alberta, Canada). Steers consumed a similar diet and received similar management each year. The objectives of this study were to: 1) determine current economic value of feed efficiency and 2) identify performance, carcass, and feed efficiency characteristics that predict: carcass value, profit, cost of gain, and feed costs. Economic data used were from 2011 values. Feed efficiency values investigated were: feed conversion ratio (FCR; feed to gain), residual feed intake (RFI), residual BW gain (RG), and residual intake and BW gain (RIG). Dependent variables were carcass value ($/steer), profit ($/steer), feed costs ($/steer • d(-1)), and cost of gain ($/kg). Independent variables were year, DMI, ADG, HCW, LM area, marbling, yield grade, dam breed, and sire breed. A 10% improvement in RG (P < 0.05) yielded the lowest cost of gain at $0.09/kg and highest carcass value at $17.92/steer. Carcass value increased (P < 0.05) as feed efficiency improved for FCR, RG, and RIG. Profit increased with a 10% improvement in feed efficiency (P < 0.05) with FCR at $34.65/steer, RG at $31.21/steer, RIG at $21.66/steer, and RFI at $11.47/steer. The carcass value prediction model explained 96% of the variation among carcasses and included HCW, marbling score, and yield grade. Average daily gain, marbling score, yield grade, DMI, HCW, and year born constituted 81% of the variation for prediction of profit. Eighty-five percent of the variation in cost of gain was explained by ADG, DMI, HCW, and year. Prediction equations were developed that excluded ADG and DMI, and included feed efficiency values. Using these equations, cost of gain was explained primarily by FCR (R(2) = 0.71). Seventy-three percent of profitability was explained, with 55% being accounted for by RG and marbling. These prediction equations represent the relative importance of factors contributing to economic success in feedlot cattle based on current prices.

High efficiency 2 micrometer laser utilizing wing-pumped Tm.sup.3+ and a laser diode array end-pumping architecture

DOEpatents

Beach, Raymond J.

1997-01-01

Wing pumping a Tm.sup.3+ doped, end pumped solid state laser generates 2 .mu.m laser radiation at high average powers with high efficiency. Using laser diode arrays to end-pump the laser rod or slab in the wing of the Tm.sup.3+ absorption band near 785 nm results in 2-for-1 quantum efficiency in Tm.sup.3+ because high Tm.sup.3+ concentrations can be used. Wing pumping allows the thermal power generated in the rod or slab to be distributed over a large enough volume to make thermal management practical in the laser gain medium even at high average power operation. The approach is applicable to CW, Q-switched, and rep-pulsed free-laser operation.

High efficiency 2 micrometer laser utilizing wing-pumped Tm{sup 3+} and a laser diode array end-pumping architecture

DOEpatents

Beach, R.J.

1997-11-18

Wing pumping a Tm{sup 3+} doped, end pumped solid state laser generates 2 {micro}m laser radiation at high average powers with high efficiency. Using laser diode arrays to end-pump the laser rod or slab in the wing of the Tm{sup 3+} absorption band near 785 nm results in 2-for-1 quantum efficiency in Tm{sup 3+} because high Tm{sup 3+} concentrations can be used. Wing pumping allows the thermal power generated in the rod or slab to be distributed over a large enough volume to make thermal management practical in the laser gain medium even at high average power operation. The approach is applicable to CW, Q-switched, and rep-pulsed free-laser operation. 7 figs.

Time-Efficient High-Rate Data Flooding in One-Dimensional Acoustic Underwater Sensor Networks

PubMed Central

Kwon, Jae Kyun; Seo, Bo-Min; Yun, Kyungsu; Cho, Ho-Shin

2015-01-01

Because underwater communication environments have poor characteristics, such as severe attenuation, large propagation delays and narrow bandwidths, data is normally transmitted at low rates through acoustic waves. On the other hand, as high traffic has recently been required in diverse areas, high rate transmission has become necessary. In this paper, transmission/reception timing schemes that maximize the time axis use efficiency to improve the resource efficiency for high rate transmission are proposed. The excellence of the proposed scheme is identified by examining the power distributions by node, rate bounds, power levels depending on the rates and number of nodes, and network split gains through mathematical analysis and numerical results. In addition, the simulation results show that the proposed scheme outperforms the existing packet train method. PMID:26528983

High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

NASA Astrophysics Data System (ADS)

Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

2015-04-01

A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

Pushing the limits of CMOS optical parametric amplifiers with USRN:Si7N3 above the two-photon absorption edge

PubMed Central

Ooi, K. J. A.; Ng, D. K. T.; Wang, T.; Chee, A. K. L.; Ng, S. K.; Wang, Q.; Ang, L. K.; Agarwal, A. M.; Kimerling, L. C.; Tan, D. T. H.

2017-01-01

CMOS platforms operating at the telecommunications wavelength either reside within the highly dissipative two-photon regime in silicon-based optical devices, or possess small nonlinearities. Bandgap engineering of non-stoichiometric silicon nitride using state-of-the-art fabrication techniques has led to our development of USRN (ultra-silicon-rich nitride) in the form of Si7N3, that possesses a high Kerr nonlinearity (2.8 × 10−13 cm2 W−1), an order of magnitude larger than that in stoichiometric silicon nitride. Here we experimentally demonstrate high-gain optical parametric amplification using USRN, which is compositionally tailored such that the 1,550 nm wavelength resides above the two-photon absorption edge, while still possessing large nonlinearities. Optical parametric gain of 42.5 dB, as well as cascaded four-wave mixing with gain down to the third idler is observed and attributed to the high photon efficiency achieved through operating above the two-photon absorption edge, representing one of the largest optical parametric gains to date on a CMOS platform. PMID:28051064

Potential Nationwide Improvements in Productivity and Health from Better Indoor Environments

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

Fisk, W.J.; Rosenfeld, A.H.

1998-05-01

Theoretical considerations and empirical data suggest that existing technologies and procedures can improve indoor environments in a manner that significantly increases productivity and health. Existing literature contains moderate to strong evidence that characteristics of buildings and indoor environments significantly influence rates of respiratory disease, allergy and asthma symptoms, sick building symptoms, and worker performance. While there is considerable uncertainty in our estimates of the magnitudes of productivity gains that may be obtained by providing better indoor environments, the projected gains are very large. For the U.S., we estimate potential annual savings and productivity gains of $6 to $19 billion frommore » reduced respiratory disease, $1 to $4 billion from reduced allergies and asthma, $10 to $20 billion from reduced sick building syndrome symptoms, and $12 to $125 billion from direct improvements in worker performance that are unrelated to health. In two example calculations, the potential financial benefits of improving indoor environments exceed costs by a factor of 8 and 14. Productivity gains that are quantified and demonstrated could serve as a strong stimulus for energy efficiency measures that simultaneously improve the indoor environment.« less

Potential nationwide improvements in productivity and health from better indoor environments

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

Fisk, W.J.; Rosenfeld, A.H.

1998-07-01

Theoretical considerations and empirical data suggest that existing technologies and procedures can improve indoor environments in a manner that significantly increases productivity and health. Existing literature contains moderate to strong evidence that characteristics of buildings and indoor environments significantly influence rates of respiratory disease, allergy and asthma symptoms, sick building symptoms, and worker performance. While there is considerable uncertainty in their estimates of the magnitudes of productivity gains that may be obtained by providing better indoor environments, the projected gains are very large. For the US, the authors estimate potential annual savings and productivity gains of $6 to $19 billionmore » from reduced respiratory disease, $1 to $4 billion from reduced allergies and asthma, $10 to $20 billion from reduced sick building syndrome symptoms, and $12 to $125 billion from direct improvements in worker performance that are unrelated to health. In two example calculations, the potential financial benefits of improving indoor environments exceed costs by a factor of 8 and 14. Productivity gains that are quantified and demonstrated could serve as a strong stimulus for energy efficiency measures that simultaneously improve the indoor environment.« less

The Next Breakthrough for Organic Photovoltaics?

PubMed

Jackson, Nicholas E; Savoie, Brett M; Marks, Tobin J; Chen, Lin X; Ratner, Mark A

2015-01-02

While the intense focus on energy level tuning in organic photovoltaic materials has afforded large gains in device performance, we argue here that strategies based on microstructural/morphological control are at least as promising in any rational design strategy. In this work, a meta-analysis of ∼150 bulk heterojunction devices fabricated with different materials combinations is performed and reveals strong correlations between power conversion efficiency and morphology-dominated properties (short-circuit current, fill factor) and surprisingly weak correlations between efficiency and energy level positioning (open-circuit voltage, enthalpic offset at the interface, optical gap). While energy level positioning should in principle provide the theoretical maximum efficiency, the optimization landscape that must be navigated to reach this maximum is unforgiving. Thus, research aimed at developing understanding-based strategies for more efficient optimization of an active layer microstructure and morphology are likely to be at least as fruitful.

A Cascaded Self-Similar Rat-Race Hybrid Coupler Architecture and its Compact Ka-Band Implementation

DTIC Science & Technology

2017-03-01

real-estate and limit the system-level performance, including bandwidth, gain, and energy - efficiency. These many challenges are positioning passive...and are used in numerous RF/mm-wave systems for radar and wireless communications. Although a Marchand balun covers a large bandwidth, it is...requires multiple λ/4 transmission lines (t-lines), making its on-chip designs very costly even for RF/mm-wave bands. Reported miniaturized rat-race

Large area application of a corn hazard model. [Soviet Union

NASA Technical Reports Server (NTRS)

Ashburn, P.; Taylor, T. W. (Principal Investigator)

1981-01-01

An application test of the crop calendar portion of a corn (maize) stress indicator model developed by the early warning, crop condition assessment component of AgRISTARS was performed over the corn for grain producing regions of the U.S.S.R. during the 1980 crop year using real data. Performance of the crop calendar submodel was favorable; efficiency gains in meteorological data analysis time were on a magnitude of 85 to 90 percent.

Efficient genotype compression and analysis of large genetic variation datasets

PubMed Central

Layer, Ryan M.; Kindlon, Neil; Karczewski, Konrad J.; Quinlan, Aaron R.

2015-01-01

Genotype Query Tools (GQT) is a new indexing strategy that expedites analyses of genome variation datasets in VCF format based on sample genotypes, phenotypes and relationships. GQT’s compressed genotype index minimizes decompression for analysis, and performance relative to existing methods improves with cohort size. We show substantial (up to 443 fold) performance gains over existing methods and demonstrate GQT’s utility for exploring massive datasets involving thousands to millions of genomes. PMID:26550772

The Trend Toward Free Trade Areas: Economic Consequences and Policy Implications for the United States

DTIC Science & Technology

1992-12-01

more efficient producers to gain large economic rents. Subsidy funding is supported by artificially high consumer pric~s or money from public budgets. If...goods and services.214 With respect to trade diversion they further expound that losses accrue to consumers : ... as imports are now purchased from... organization that has taken concrete steps toward an Asian FTA, and because of space limitations, the other groupings are not considered in this document

Qaharir Field, Oman: A textbook case

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

O`Dell, P.M.

1995-12-31

Qaharir Field is located in the southern part of the Sultanate of Oman. Like several fields in South Oman, it produces a light oil with very little solution gas. Qaharir Field contains a large depletion reservoir and several natural water drive reservoirs. There is, therefore, a large variation in the primary recovery efficiencies. A recent petroleum engineering review of this field determined the reservoir drive mechanisms and provided a basis for further development plans. This review of Qaharir Field demonstrates the application of conventional reservoir engineering tools to gain an understanding of the reservoir in sufficient detail to select andmore » plan the next development objectives.« less

Efficient light collection from crystal scintillators using a compound parabolic concentrator coupled to an avalanche photodiode

NASA Astrophysics Data System (ADS)

Jenke, P. A.; Briggs, M. S.; Bhat, P. N.; Reardon, P.; Connaughton, V.; Wilson-Hodge, C.

2013-09-01

In support of improved gamma-ray detectors for astrophysics and observations of Terrestrial Gamma-ray Flashes (TGFs), we have designed a new approach for the collection and detection of optical photons from scintillators such as Sodium Iodide and Lanthanum Bromide using a light concentrator coupled to an Avalanche photodiode (APD). The APD has many advantages over traditional photomultiplier tubes such as their low power consumption, their compact size, their durability, and their very high quantum efficiency. The difficulty in using these devices in gamma-ray astronomy has been coupling their relatively small active area to the large scintillators necessary for gamma-ray science. Our solution is to use an acrylic Compound Parabolic Concentrator (CPC) to match the large output area of the scintillation crystal to the smaller photodiode. These non-imaging light concentrators exceed the light concentration of focused optics and are light and inexpensive to produce. We present our results from the analysis and testing of such a system including gains in light collecting efficiency, energy resolution of nuclear decay lines, as well as our design for a new, fast TGF detector.

High efficiency Raman memory by suppressing radiation trapping

NASA Astrophysics Data System (ADS)

Thomas, S. E.; Munns, J. H. D.; Kaczmarek, K. T.; Qiu, C.; Brecht, B.; Feizpour, A.; Ledingham, P. M.; Walmsley, I. A.; Nunn, J.; Saunders, D. J.

2017-06-01

Raman interactions in alkali vapours are used in applications such as atomic clocks, optical signal processing, generation of squeezed light and Raman quantum memories for temporal multiplexing. To achieve a strong interaction the alkali ensemble needs both a large optical depth and a high level of spin-polarisation. We implement a technique known as quenching using a molecular buffer gas which allows near-perfect spin-polarisation of over 99.5 % in caesium vapour at high optical depths of up to ˜ 2× {10}5; a factor of 4 higher than can be achieved without quenching. We use this system to explore efficient light storage with high gain in a GHz bandwidth Raman memory.

Itinerant Microwave Photon Detector

NASA Astrophysics Data System (ADS)

Royer, Baptiste; Grimsmo, Arne L.; Choquette-Poitevin, Alexandre; Blais, Alexandre

2018-05-01

The realization of a high-efficiency microwave single photon detector is a long-standing problem in the field of microwave quantum optics. Here, we propose a quantum nondemolition, high-efficiency photon detector that can readily be implemented in present state-of-the-art circuit quantum electrodynamics. This scheme works in a continuous fashion, gaining information about the photon arrival time as well as about its presence. The key insight that allows us to circumvent the usual limitations imposed by measurement backaction is the use of long-lived dark states in a small ensemble of inhomogeneous artificial atoms to increase the interaction time between the photon and the measurement device. Using realistic system parameters, we show that large detection fidelities are possible.

InSilico DB genomic datasets hub: an efficient starting point for analyzing genome-wide studies in GenePattern, Integrative Genomics Viewer, and R/Bioconductor.

PubMed

Coletta, Alain; Molter, Colin; Duqué, Robin; Steenhoff, David; Taminau, Jonatan; de Schaetzen, Virginie; Meganck, Stijn; Lazar, Cosmin; Venet, David; Detours, Vincent; Nowé, Ann; Bersini, Hugues; Weiss Solís, David Y

2012-11-18

Genomics datasets are increasingly useful for gaining biomedical insights, with adoption in the clinic underway. However, multiple hurdles related to data management stand in the way of their efficient large-scale utilization. The solution proposed is a web-based data storage hub. Having clear focus, flexibility and adaptability, InSilico DB seamlessly connects genomics dataset repositories to state-of-the-art and free GUI and command-line data analysis tools. The InSilico DB platform is a powerful collaborative environment, with advanced capabilities for biocuration, dataset sharing, and dataset subsetting and combination. InSilico DB is available from https://insilicodb.org.

Mode-locked solid state lasers using diode laser excitation

DOEpatents

Holtom, Gary R [Boston, MA

2012-03-06

A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. An asymmetric cavity provides relatively large beam spot sizes in gain medium to permit efficient coupling to a volume pumped by a laser diode bar. The cavity can include a collimation region with a controlled beam spot size for insertion of a saturable absorber and dispersion components. Beam spot size is selected to provide stable mode locking based on Kerr lensing. Pulse durations of less than 100 fs can be achieved in Yb:KGW.

Custom instruction set NIOS-based OFDM processor for FPGAs

NASA Astrophysics Data System (ADS)

Meyer-Bäse, Uwe; Sunkara, Divya; Castillo, Encarnacion; Garcia, Antonio

2006-05-01

Orthogonal Frequency division multiplexing (OFDM) spread spectrum technique, sometimes also called multi-carrier or discrete multi-tone modulation, are used in bandwidth-efficient communication systems in the presence of channel distortion. The benefits of OFDM are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. OFDM is the basis for the European digital audio broadcasting (DAB) standard, the global asymmetric digital subscriber line (ADSL) standard, in the IEEE 802.11 5.8 GHz band standard, and ongoing development in wireless local area networks. The modulator and demodulator in an OFDM system can be implemented by use of a parallel bank of filters based on the discrete Fourier transform (DFT), in case the number of subchannels is large (e.g. K > 25), the OFDM system are efficiently implemented by use of the fast Fourier transform (FFT) to compute the DFT. We have developed a custom FPGA-based Altera NIOS system to increase the performance, programmability, and low power in mobil wireless systems. The overall gain observed for a 1024-point FFT ranges depending on the multiplier used by the NIOS processor between a factor of 3 and 16. A careful optimization described in the appendix yield a performance gain of up to 77% when compared with our preliminary results.

Efficient partitioning and assignment on programs for multiprocessor execution

NASA Technical Reports Server (NTRS)

Standley, Hilda M.

1993-01-01

The general problem studied is that of segmenting or partitioning programs for distribution across a multiprocessor system. Efficient partitioning and the assignment of program elements are of great importance since the time consumed in this overhead activity may easily dominate the computation, effectively eliminating any gains made by the use of the parallelism. In this study, the partitioning of sequentially structured programs (written in FORTRAN) is evaluated. Heuristics, developed for similar applications are examined. Finally, a model for queueing networks with finite queues is developed which may be used to analyze multiprocessor system architectures with a shared memory approach to the problem of partitioning. The properties of sequentially written programs form obstacles to large scale (at the procedure or subroutine level) parallelization. Data dependencies of even the minutest nature, reflecting the sequential development of the program, severely limit parallelism. The design of heuristic algorithms is tied to the experience gained in the parallel splitting. Parallelism obtained through the physical separation of data has seen some success, especially at the data element level. Data parallelism on a grander scale requires models that accurately reflect the effects of blocking caused by finite queues. A model for the approximation of the performance of finite queueing networks is developed. This model makes use of the decomposition approach combined with the efficiency of product form solutions.

paraGSEA: a scalable approach for large-scale gene expression profiling

PubMed Central

Peng, Shaoliang; Yang, Shunyun

2017-01-01

Abstract More studies have been conducted using gene expression similarity to identify functional connections among genes, diseases and drugs. Gene Set Enrichment Analysis (GSEA) is a powerful analytical method for interpreting gene expression data. However, due to its enormous computational overhead in the estimation of significance level step and multiple hypothesis testing step, the computation scalability and efficiency are poor on large-scale datasets. We proposed paraGSEA for efficient large-scale transcriptome data analysis. By optimization, the overall time complexity of paraGSEA is reduced from O(mn) to O(m+n), where m is the length of the gene sets and n is the length of the gene expression profiles, which contributes more than 100-fold increase in performance compared with other popular GSEA implementations such as GSEA-P, SAM-GS and GSEA2. By further parallelization, a near-linear speed-up is gained on both workstations and clusters in an efficient manner with high scalability and performance on large-scale datasets. The analysis time of whole LINCS phase I dataset (GSE92742) was reduced to nearly half hour on a 1000 node cluster on Tianhe-2, or within 120 hours on a 96-core workstation. The source code of paraGSEA is licensed under the GPLv3 and available at http://github.com/ysycloud/paraGSEA. PMID:28973463

Planar-Structure Perovskite Solar Cells with Efficiency beyond 21.

PubMed

Jiang, Qi; Chu, Zema; Wang, Pengyang; Yang, Xiaolei; Liu, Heng; Wang, Ye; Yin, Zhigang; Wu, Jinliang; Zhang, Xingwang; You, Jingbi

2017-12-01

Low temperature solution processed planar-structure perovskite solar cells gain great attention recently, while their power conversions are still lower than that of high temperature mesoporous counterpart. Previous reports are mainly focused on perovskite morphology control and interface engineering to improve performance. Here, this study systematically investigates the effect of precise stoichiometry, especially the PbI 2 contents on device performance including efficiency, hysteresis and stability. This study finds that a moderate residual of PbI 2 can deliver stable and high efficiency of solar cells without hysteresis, while too much residual PbI 2 will lead to serious hysteresis and poor transit stability. Solar cells with the efficiencies of 21.6% in small size (0.0737 cm 2 ) and 20.1% in large size (1 cm 2 ) with moderate residual PbI 2 in perovskite layer are obtained. The certificated efficiency for small size shows the efficiency of 20.9%, which is the highest efficiency ever recorded in planar-structure perovskite solar cells, showing the planar-structure perovskite solar cells are very promising. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Generation of twin beams using four-wave mixing: theory and experiments

NASA Astrophysics Data System (ADS)

Glorieux, Quentin; Dubessy, Romain; Guibal, Samuel; Guidoni, Luca; Likforman, Jean Pierre; Coudreau, Thomas; Arimondo, Ennio

2010-03-01

Recently, four-wave mixing has drawn a large interest as a simple and efficient source of non classical light [1]. Using a strong pump (400 mW) propagating in a heated rubidium cell, it is possible to generate quantum correlated beams. The set-up has the advantage of both simplicity (no resonant cavity) and efficiency (we measure up to 9.5 dB of noise reduction below the standard quantum limit). However, up to now, no microscopic model was proposed for this phenomenon. Here we present for the first time such a model [2] based on the Heisenberg-Langevin input-output formalism [3] and we verify that the classical gain and the quantum correlations are in very good agreement with our experimental datas. A new regime of correlation generation in absence of gain is also proposed. [4pt] [1] C.F. McCormick et al., Opt. Lett (2007) vol. 32 p. 178[0pt] [2] Q. Glorieux et al., in preparation (2010)[0pt] [3] P. Kolchin, Phys. Rev. A (2007) vol. 75 p. 33814

Multi-stage decoding for multi-level block modulation codes

NASA Technical Reports Server (NTRS)

Lin, Shu; Kasami, Tadao

1991-01-01

Various types of multistage decoding for multilevel block modulation codes, in which the decoding of a component code at each stage can be either soft decision or hard decision, maximum likelihood or bounded distance are discussed. Error performance for codes is analyzed for a memoryless additive channel based on various types of multi-stage decoding, and upper bounds on the probability of an incorrect decoding are derived. It was found that, if component codes of a multi-level modulation code and types of decoding at various stages are chosen properly, high spectral efficiency and large coding gain can be achieved with reduced decoding complexity. It was found that the difference in performance between the suboptimum multi-stage soft decision maximum likelihood decoding of a modulation code and the single stage optimum decoding of the overall code is very small, only a fraction of dB loss in SNR at the probability of an incorrect decoding for a block of 10(exp -6). Multi-stage decoding of multi-level modulation codes really offers a way to achieve the best of three worlds, bandwidth efficiency, coding gain, and decoding complexity.

Improved integral images compression based on multi-view extraction

NASA Astrophysics Data System (ADS)

Dricot, Antoine; Jung, Joel; Cagnazzo, Marco; Pesquet, Béatrice; Dufaux, Frédéric

2016-09-01

Integral imaging is a technology based on plenoptic photography that captures and samples the light-field of a scene through a micro-lens array. It provides views of the scene from several angles and therefore is foreseen as a key technology for future immersive video applications. However, integral images have a large resolution and a structure based on micro-images which is challenging to encode. A compression scheme for integral images based on view extraction has previously been proposed, with average BD-rate gains of 15.7% (up to 31.3%) reported over HEVC when using one single extracted view. As the efficiency of the scheme depends on a tradeoff between the bitrate required to encode the view and the quality of the image reconstructed from the view, it is proposed to increase the number of extracted views. Several configurations are tested with different positions and different number of extracted views. Compression efficiency is increased with average BD-rate gains of 22.2% (up to 31.1%) reported over the HEVC anchor, with a realistic runtime increase.

Feed efficiency of tropically adapted cattle when fed in winter or spring in a temperate location

USDA-ARS?s Scientific Manuscript database

Earlier work has shown that young, tropically adapted cattle do not gain as rapidly as temperately adapted cattle during the winter in OK. The objective for this study was to determine if efficiency of gains was also impacted in tropically adapted cattle and if efficiency is consistent in different...

Inverse Statistics and Asset Allocation Efficiency

NASA Astrophysics Data System (ADS)

Bolgorian, Meysam

In this paper using inverse statistics analysis, the effect of investment horizon on the efficiency of portfolio selection is examined. Inverse statistics analysis is a general tool also known as probability distribution of exit time that is used for detecting the distribution of the time in which a stochastic process exits from a zone. This analysis was used in Refs. 1 and 2 for studying the financial returns time series. This distribution provides an optimal investment horizon which determines the most likely horizon for gaining a specific return. Using samples of stocks from Tehran Stock Exchange (TSE) as an emerging market and S&P 500 as a developed market, effect of optimal investment horizon in asset allocation is assessed. It is found that taking into account the optimal investment horizon in TSE leads to more efficiency for large size portfolios while for stocks selected from S&P 500, regardless of portfolio size, this strategy does not only not produce more efficient portfolios, but also longer investment horizons provides more efficiency.

Ultrafast laser direct hard-mask writing for high efficiency c-Si texture designs

NASA Astrophysics Data System (ADS)

Kumar, Kitty; Lee, Kenneth K. C.; Nogami, Jun; Herman, Peter R.; Kherani, Nazir P.

2013-03-01

This study reports a high-resolution hard-mask laser writing technique to facilitate the selective etching of crystalline silicon (c-Si) into an inverted-pyramidal texture with feature size and periodicity on the order of the wavelength which, thus, provides for both anti-reflection and effective light-trapping of infrared and visible light. The process also enables engineered positional placement of the inverted-pyramid thereby providing another parameter for optimal design of an optically efficient pattern. The proposed technique, a non-cleanroom process, is scalable for large area micro-fabrication of high-efficiency thin c-Si photovoltaics. Optical wave simulations suggest the fabricated textured surface with 1.3 μm inverted-pyramids and a single anti-reflective coating increases the relative energy conversion efficiency by 11% compared to the PERL-cell texture with 9 μm inverted pyramids on a 400 μm thick wafer. This efficiency gain is anticipated to improve further for thinner wafers due to enhanced diffractive light trapping effects.

Radiation characteristics of Leaky Surface Plasmon polaritons of graphene

NASA Astrophysics Data System (ADS)

Mohadesi, V.; Asgari, A.; Siahpoush, V.

2018-07-01

High efficient coupling of graphene surface plasmons to far field radiation is possible by some techniques and can be used in the radiating applications. Besides of the coupling efficiency, the angular distribution of the radiated power is an important parameter in the radiating devices performance. In this paper we investigate the gain of the far field radiation related to the coupling of graphene surface plasmons via a high permittivity medium located close to the graphene. Our results show that high directive radiation and high coupling efficiency can be obtained by this technique and gain and directivity of radiation can be modified by graphene characteristics such as chemical potential and also quality of the graphene. Raising the chemical potential of graphene leads to increase the gain of the radiation as the result of amplifying the directivity of the radiation. Furthermore, high values of relaxation time lead to high directive and strong coupling which raises the maximum value of gain in efficient coupling angle. Tunable characteristics of gain and directivity in this structure can be important designing reconfigurable THz radiating devices.

High-efficiency cavity-dumped micro-chip Yb:YAG laser

NASA Astrophysics Data System (ADS)

Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

2014-09-01

High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

Decomposition of potential efficiency gains from hospital mergers in Greece.

PubMed

Flokou, Angeliki; Aletras, Vassilis; Niakas, Dimitris

2017-12-01

This paper evaluates the technical efficiency of 71 Greek public hospitals and examines potential efficiency gains from 13 candidate mergers among them. Efficiency assessments are performed using bootstrapped Data Envelopment Analysis (DEA) whilst merger analysis is conducted by applying the Bogetoft and Wang methodology which allows the overall potential merger gains to be decomposed into three main components of inefficiency, namely technical (or learning), scope (or harmony) and scale (or size) effects. Thus, the analysis provides important insights not only on the magnitude of the potential total efficiency gains but also on their sources. The overall analysis is conducted in the context of a complete methodological framework where methods for outlier detection, returns to scale identification, and bias corrections for DEA estimations are also applied. Mergers are analyzed under the assumptions of constant, variable and non-decreasing returns to scale in an input oriented DEA model with three inputs and three outputs. The main finding of the study indicates that almost all mergers show substantial potential room for efficiency improvement, which is mainly attributed to the pre-merger technical inefficiencies of the individual hospitals and therefore it might be possible to be achieved without the need of implementing full-scale mergers. The same -though, at a lower extent- applies to the harmony effect whilst the size effect shows marginal or even negative gains.

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

Veale, M.; Purohit, P.; Lawson, W.

In this paper we consider the design of a four-cavity, high-gain K-band gyroklystron experiment for high gradient structure testing. The frequency doubling gyroklystron utilizes a beam voltage of 500 kV and a beam current of 200 A from a magnetron injection gun (MIG) originally designed for a lower-frequency device. The microwave circuit features input and gain cavities in the circular TE{sub 011} mode and penultimate and output cavities that operate at the second harmonic in the TE{sub 021} mode. We investigate the MIG performance and study the behavior of the circuit for different values of perpendicular to parallel velocity ratiomore » (α= V{sub ⊥}/ V{sub z}). This microwave tube is expected to be able to produce at least 20 MW of power in 1μs pulses at a repetition rate of at least 120 Hz. A maximum efficiency of 26% and a large signal gain of 58 dB under zero-drive stable conditions were simulated for a velocity ratio equal to 1.35.« less

Josephson parametric converter saturation and higher order effects

NASA Astrophysics Data System (ADS)

Liu, G.; Chien, T.-C.; Cao, X.; Lanes, O.; Alpern, E.; Pekker, D.; Hatridge, M.

2017-11-01

Microwave parametric amplifiers based on Josephson junctions have become indispensable components of many quantum information experiments. One key limitation which has not been well predicted by theory is the gain saturation behavior which limits the amplifier's ability to process large amplitude signals. The typical explanation for this behavior in phase-preserving amplifiers based on three-wave mixing, such as the Josephson Parametric Converter, is pump depletion, in which the consumption of pump photons to produce amplification results in a reduction in gain. However, in this work, we present experimental data and theoretical calculations showing that the fourth-order Kerr nonlinearities inherent in Josephson junctions are the dominant factor. The Kerr-based theory has the unusual property of causing saturation to both lower and higher gains, depending on bias conditions. This work presents an efficient methodology for optimizing device performance in the presence of Kerr nonlinearities while retaining device tunability and points to the necessity of controlling higher-order Hamiltonian terms to make further improvements in parametric devices.

Gain assisted coherent control of microwave pulse in a one dimensional array of artificial atoms

NASA Astrophysics Data System (ADS)

Waqas, Mohsin; Ayaz, M. Q.; Waseem, M.; Qamar, Sajid; Qamar, Shahid

2018-06-01

We study the coherent propagation of a microwave pulse through a one-dimensional array of artificial atoms. The scheme is based upon gain assisted propagation of the pulse using two-photon Raman transition in a three-level superconducting artificial atoms (SAAs) coupled to a microwave transmission line. Our results show that the group velocity can be significantly reduced by increasing the Rabi frequency of the pump fields which in turn can lead to an efficient storage of the pulse inside a 1D array of SAAs. Further, the intensity of the transmitted pulse increases with the number of artificial atoms owing to the gain associated with the two-photon Raman transition. Our results also show that the window width decreases for both scattering and negligible scattering cases with the increase in the number of SAAs. The fidelity of the system also remains high even after the passage of the pulse through a large number of SAAs.

Image sensor system with bio-inspired efficient coding and adaptation.

PubMed

Okuno, Hirotsugu; Yagi, Tetsuya

2012-08-01

We designed and implemented an image sensor system equipped with three bio-inspired coding and adaptation strategies: logarithmic transform, local average subtraction, and feedback gain control. The system comprises a field-programmable gate array (FPGA), a resistive network, and active pixel sensors (APS), whose light intensity-voltage characteristics are controllable. The system employs multiple time-varying reset voltage signals for APS in order to realize multiple logarithmic intensity-voltage characteristics, which are controlled so that the entropy of the output image is maximized. The system also employs local average subtraction and gain control in order to obtain images with an appropriate contrast. The local average is calculated by the resistive network instantaneously. The designed system was successfully used to obtain appropriate images of objects that were subjected to large changes in illumination.

Innovations in percutaneous nephrolithotomy.

PubMed

Tailly, Thomas; Denstedt, John

2016-12-01

Technical innovations in all aspects of percutaneous nephrolithotomy have changed the field considerably. The current review is aimed at reporting on the most recent advancements in the field of percutaneous nephrolithotomy. Improvements in CT imaging and the possibility of 3D rendering have dethroned the intravenous pyelogram as gold standard for pre-operative imaging. Where gaining access in the lower pole in prone position with telescopic metal dilators, placing a 30F tract used to be standard, the plethora of alternatives provides the trained surgeon with a large armamentarium to tackle any obstacle. Novel lithotripters appear more efficient than their predecessors and with tubeless PCNL gaining some momentum, ambulatory PCNL is slowly but surely becoming feasible rather than fictional. Copyright © 2016 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

Four-wave-mixing suppression in Er 3+-fiber amplifiers by backward pumping

NASA Astrophysics Data System (ADS)

Adel, P.; Engelbrecht, M.; Wandt, D.; Fallnich, C.

2007-03-01

Amplification of chirped fs-pulses in an Erbium doped fiber amplifier upto 0.8 μJ resulted in an additional peak in the spectrum at 1584 nm. This peak, attributable to four-wave-mixing between the signal centered at 1559 nm and amplified spontaneous emission at 1534 nm, hinders the temporal recompression of the amplified chirped pulse. Compared to the forward pumping configuration, this four-wave-mixing in the amplifier was largely reduced in a backward pumping configuration. Based on simulations, explanations for the observed influence of the pump direction on the four-wave-mixing efficiency are presented. The results pointed out that the gain spectrum distribution along the fiber strongly influences four-wave-mixing effects in fiber amplifiers even for constant overall gain spectrum.

Comparative Study of DC and AC Microgrids in Commercial Buildings Across Different Climates and Operating Profiles: Preprint

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

Fregosi, D.; Ravula, S.; Brhlik, D.

2015-04-22

Bosch has developed and demonstrated a novel DC microgrid system designed to maximize utilization efficiency for locally generated photovoltaic energy while offering high reliability, safety, redundancy, and reduced cost compared to equivalent AC systems. Several demonstration projects validating the system feasibility and expected efficiency gains have been completed and additional ones are in progress. This work gives an overview of the Bosch DC microgrid system and presents key results from a large simulation study done to estimate the energy savings of the Bosch DC microgrid over conventional AC systems. The study examined the system performance in locations across the Unitedmore » States for several commercial building types and operating profiles and found that the Bosch DC microgrid uses generated PV energy 6%–8% more efficiently than traditional AC systems.« less

Array feed synthesis for correction of reflector distortion and Vernier Beamsteering

NASA Technical Reports Server (NTRS)

Blank, S. J.; Imbriale, W. A.

1986-01-01

An algorithmic procedure for the synthesis of planar array feeds for paraboloidal reflectors is described which simultaneously provides electronic correction of systematic reflector surface distortions as well as a Vernier electronic beamsteering capability. Simple rules of thumb for the optimum choice of planar array feed configuration (i.e., number and type of elements) are derived from a parametric study made using the synthesis procedure. A number of f/D ratios and distortion models were examined that are typical of large paraboloidal reflectors. Numerical results are presented showing that, for the range of distortion models considered, good on-axis gain restoration can be achieved with as few as seven elements. For beamsteering to +/- 1 beamwidth (BW), 19 elements are required. For arrays with either 7 or 19 elements, the results indicate that the use of high-aperture-efficiency elements (e.g., disk-on-rod and short backfire) in the array yields higher system gain than can be obtained with elements having lower aperture efficiency (e.g., open-ended waveguides). With 37 elements, excellent gain and beamsteering performance to +/- 1.5 BW are obtained independent of the assumed effective aperture of the array element. An approximate expression is derived for the focal-plane field distribution of the distorted reflector. Contour plots of the focal-plane fields are also presented for various distortion and beam scan angle cases. The results obtained show the effectiveness of the array feed approach.

Future-oriented maintenance strategy based on automated processes is finding its way into large astronomical facilities at remote observing sites

NASA Astrophysics Data System (ADS)

Silber, Armin; Gonzalez, Christian; Pino, Francisco; Escarate, Patricio; Gairing, Stefan

2014-08-01

With expanding sizes and increasing complexity of large astronomical observatories on remote observing sites, the call for an efficient and recourses saving maintenance concept becomes louder. The increasing number of subsystems on telescopes and instruments forces large observatories, like in industries, to rethink conventional maintenance strategies for reaching this demanding goal. The implementation of full-, or semi-automatic processes for standard service activities can help to keep the number of operating staff on an efficient level and to reduce significantly the consumption of valuable consumables or equipment. In this contribution we will demonstrate on the example of the 80 Cryogenic subsystems of the ALMA Front End instrument, how an implemented automatic service process increases the availability of spare parts and Line Replaceable Units. Furthermore how valuable staff recourses can be freed from continuous repetitive maintenance activities, to allow focusing more on system diagnostic tasks, troubleshooting and the interchanging of line replaceable units. The required service activities are decoupled from the day-to-day work, eliminating dependencies on workload peaks or logistic constrains. The automatic refurbishing processes running in parallel to the operational tasks with constant quality and without compromising the performance of the serviced system components. Consequentially that results in an efficiency increase, less down time and keeps the observing schedule on track. Automatic service processes in combination with proactive maintenance concepts are providing the necessary flexibility for the complex operational work structures of large observatories. The gained planning flexibility is allowing an optimization of operational procedures and sequences by considering the required cost efficiency.

A bandwidth efficient coding scheme for the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Pietrobon, Steven S.; Costello, Daniel J., Jr.

1991-01-01

As a demonstration of the performance capabilities of trellis codes using multidimensional signal sets, a Viterbi decoder was designed. The choice of code was based on two factors. The first factor was its application as a possible replacement for the coding scheme currently used on the Hubble Space Telescope (HST). The HST at present uses the rate 1/3 nu = 6 (with 2 (exp nu) = 64 states) convolutional code with Binary Phase Shift Keying (BPSK) modulation. With the modulator restricted to a 3 Msym/s, this implies a data rate of only 1 Mbit/s, since the bandwidth efficiency K = 1/3 bit/sym. This is a very bandwidth inefficient scheme, although the system has the advantage of simplicity and large coding gain. The basic requirement from NASA was for a scheme that has as large a K as possible. Since a satellite channel was being used, 8PSK modulation was selected. This allows a K of between 2 and 3 bit/sym. The next influencing factor was INTELSAT's intention of transmitting the SONET 155.52 Mbit/s standard data rate over the 72 MHz transponders on its satellites. This requires a bandwidth efficiency of around 2.5 bit/sym. A Reed-Solomon block code is used as an outer code to give very low bit error rates (BER). A 16 state rate 5/6, 2.5 bit/sym, 4D-8PSK trellis code was selected. This code has reasonable complexity and has a coding gain of 4.8 dB compared to uncoded 8PSK (2). This trellis code also has the advantage that it is 45 deg rotationally invariant. This means that the decoder needs only to synchronize to one of the two naturally mapped 8PSK signals in the signal set.

A two steps solution approach to solving large nonlinear models: application to a problem of conjunctive use.

PubMed

Vieira, J; Cunha, M C

2011-01-01

This article describes a solution method of solving large nonlinear problems in two steps. The two steps solution approach takes advantage of handling smaller and simpler models and having better starting points to improve solution efficiency. The set of nonlinear constraints (named as complicating constraints) which makes the solution of the model rather complex and time consuming is eliminated from step one. The complicating constraints are added only in the second step so that a solution of the complete model is then found. The solution method is applied to a large-scale problem of conjunctive use of surface water and groundwater resources. The results obtained are compared with solutions determined with the direct solve of the complete model in one single step. In all examples the two steps solution approach allowed a significant reduction of the computation time. This potential gain of efficiency of the two steps solution approach can be extremely important for work in progress and it can be particularly useful for cases where the computation time would be a critical factor for having an optimized solution in due time.

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

Shang, W. L.; Betti, R.; Hu, S. X.

Here, it is shown that inertial fusion targets designed with low implosion velocities can be shock ignited using laser–plasma interaction generated hot electrons (hot-e) to obtain high-energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e, which can only be produced on a large laser facility like the National Ignition Facility, with the laser to hot-e conversion efficiency greater than 10% at laser intensities ~10 16 W/cm 2.

Laser Based Phosphor Converted Solid State White Light Emitters

NASA Astrophysics Data System (ADS)

Cantore, Michael

Artificial lighting and as a consequence the ability to be productive when the sun does not shine may be a profound achievement in society that is largely taken for granted. As concerns arise due to our dependence on energy sources with finite lifespan or environmentally negative effects, efforts to reduce energy consumption and create clean renewable alternatives has become highly valued. In the scope of artificial lighting, the use of incandescent lamps has shifted to more efficient light sources. Fluorescent lighting made the first big gains in efficiency over incandescent lamps with peak efficiency for mature designs reaching luminous efficacy of approximately 90 lm/W; more than three times as efficient as an incandescent lamp. Lamps based on light emitting diodes (LEDs) which can produce light at even greater efficiency, color quality and without the potential for hazardous chemical release from lamp failure. There is a significant challenge with LED based light sources. Their peak efficiency occurs at low current densities and then droops as the current density increases. Laser diodes (LDs) do not suffer from decreasing efficiency due to increased current. An alternative solid state light source using LDs has potential to make further gains in efficiency as well as allow novel illuminant designs which may be impractical or even impossible even with LED or other conventional sources. While similar to LEDS, the use of LDs does present new challenges largely due to the increased optical power density which must be accommodated in optics and phosphor materials. Single crystal YAG:Ce has been shown to be capable of enduring this more extreme operating environment while retaining the optical and fluorescing qualities desired for use as a wavelength converter in phosphor converted LD based white emitting systems. The incorporation of this single crystal phosphor in a system with a commercial laser diode with peak wall plug efficiency of 31% resulted in emission of white light with a luminous efficacy of 86.7 lm/W at a current of 1.4A. A total luminous flux of 1100 lm with luminous efficacy of 76 lm/W at 3.0 A current was achieved. Simulations have been conducted which show that as the InGaN LD technology matures towards the efficiencies of about 75%, which has been observed in the GaAs material system, luminous efficacy of similar blue LD with single crystal YAG:Ce systems will exceed 200 lm/W.

Effects of two commercially available feline diets on glucose and insulin concentrations, insulin sensitivity and energetic efficiency of weight gain.

PubMed

Coradini, M; Rand, J S; Morton, J M; Rawlings, J M

2011-10-01

A low-carbohydrate, high-protein (LCHP) diet is often recommended for the prevention and management of diabetes in cats; however, the effect of macronutrient composition on insulin sensitivity and energetic efficiency for weight gain is not known. The present study compared the effect in adult cats (n 32) of feeding a LCHP (23 and 47 % metabolisable energy (ME)) and a high-carbohydrate, low-protein (HCLP) diet (51 and 21 % ME) on fasting and postprandial glucose and insulin concentrations, and on insulin sensitivity. Tests were done in the 4th week of maintenance feeding and after 8 weeks of ad libitum feeding, when weight gain and energetic efficiency of each diet were also measured. When fed at maintenance energy, the HCLP diet resulted in higher postprandial glucose and insulin concentrations. When fed ad libitum, the LCHP diet resulted in greater weight gain (P < 0.01), and was associated with higher energetic efficiency. Overweight cats eating the LCHP diet had similar postprandial glucose concentrations to lean cats eating the HCLP diet. Insulin sensitivity was not different between the diets when cats were lean or overweight, but glucose effectiveness was higher after weight gain in cats fed the HCLP diet. According to the present results, LCHP diets fed at maintenance requirements might benefit cats with multiple risk factors for developing diabetes. However, ad libitum feeding of LCHP diets is not recommended as they have higher energetic efficiency and result in greater weight gain.

Measuring learning gain: Comparing anatomy drawing screencasts and paper-based resources.

PubMed

Pickering, James D

2017-07-01

The use of technology-enhanced learning (TEL) resources is now a common tool across a variety of healthcare programs. Despite this popular approach to curriculum delivery there remains a paucity in empirical evidence that quantifies the change in learning gain. The aim of the study was to measure the changes in learning gain observed with anatomy drawing screencasts in comparison to a traditional paper-based resource. Learning gain is a widely used term to describe the tangible changes in learning outcomes that have been achieved after a specific intervention. In regard to this study, a cohort of Year 2 medical students voluntarily participated and were randomly assigned to either a screencast or textbook group to compare changes in learning gain across resource type. Using a pre-test/post-test protocol, and a range of statistical analyses, the learning gain was calculated at three test points: immediate post-test, 1-week post-test and 4-week post-test. Results at all test points revealed a significant increase in learning gain and large effect sizes for the screencast group compared to the textbook group. Possible reasons behind the difference in learning gain are explored by comparing the instructional design of both resources. Strengths and weaknesses of the study design are also considered. This work adds to the growing area of research that supports the effective design of TEL resources which are complimentary to the cognitive theory of multimedia learning to achieve both an effective and efficient learning resource for anatomical education. Anat Sci Educ 10: 307-316. © 2016 American Association of Anatomists. © 2016 American Association of Anatomists.

Visual attention mitigates information loss in small- and large-scale neural codes

PubMed Central

Sprague, Thomas C; Saproo, Sameer; Serences, John T

2015-01-01

Summary The visual system transforms complex inputs into robust and parsimonious neural codes that efficiently guide behavior. Because neural communication is stochastic, the amount of encoded visual information necessarily decreases with each synapse. This constraint requires processing sensory signals in a manner that protects information about relevant stimuli from degradation. Such selective processing – or selective attention – is implemented via several mechanisms, including neural gain and changes in tuning properties. However, examining each of these effects in isolation obscures their joint impact on the fidelity of stimulus feature representations by large-scale population codes. Instead, large-scale activity patterns can be used to reconstruct representations of relevant and irrelevant stimuli, providing a holistic understanding about how neuron-level modulations collectively impact stimulus encoding. PMID:25769502

Violet-to-Blue Gain and Lasing from Colloidal CdS Nanoplatelets: Low-Threshold Stimulated Emission Despite Low Photoluminescence Quantum Yield

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

Diroll, Benjamin T.; Talapin, Dmitri V.; Schaller, Richard D.

Amplified spontaneous emission (ASE) and lasing from solution-processed materials are demonstrated in the challenging violet-to-blue (430–490 nm) spectral region for colloidal nanoplatelets of CdS and newly synthesized core/shell CdS/ZnS nanoplatelets. Despite modest band-edge photoluminescence quantum yields of 2% or less for single excitons, which we show results from hole trapping, the samples exhibit low ASE thresholds. Furthermore, four-monolayer CdS samples show ASE at shorter wavelengths than any reported film of colloidal quantum-confined material. This work underlines that low quantum yields for single excitons do not necessarily lead to a poor gain medium. The low ASE thresholds originate from negligible dispersionmore » in thickness, large absorption cross sections of 2.8 × 10–14 cm–2, and rather slow (150 to 300 ps) biexciton recombination. We show that under higher-fluence excitation, ASE can kinetically outcompete hole trapping. Using nanoplatelets as the gain medium, lasing is observed in a linear optical cavity. This work confirms the fundamental advantages of colloidal quantum well structures as gain media, even in the absence of high photoluminescence efficiency.« less

Emitter utilization in heterojunction bipolar transistors

NASA Astrophysics Data System (ADS)

Quach, T.; Jenkins, T.; Barrette, J.; Bozada, C.; Cerny, C.; Desalvo, G.; Dettmer, R.; Ebel, J.; Gillespie, J.; Havasy, C.; Ito, C.; Nakano, K.; Pettiford, C.; Sewell, J.; Via, D.; Anholt, R.

1997-09-01

We compare measured collector current densities, cutoff frequencies ( ft), and transducer gains for thermally shunted heterojunction bipolar transistors with 2-16 μm emitter dot diameters or 2-8 μm emitter bar widths with models of the emitter utilization factors. Models that do not take emitter resistance into account predict that the d.c. utilization factors are below 0.7 for collector current densities greater than 6 × 10 4 A cm -2 and emitter diameters or widths greater than 8 μm. However, because the current gains are compressed by the emitter resistances at those current densities, the measured utilization factors are close to 1, which agrees with models that include emitter resistance. A.c. utilization factors are evident in the transistor Y parameters. For example, Re|Y 21z.sfnc drops off at high frequencies more steeply in HBTs with large emitter diameters or widths than in small ones. However, measured data shows that the HBT a.c. current gains h21 or ft values are not influenced by the a.c. utilization factor. A.c. utilization effects on HBT performance parameters such as small signal and power gains, output power, and power added efficiency are also examined.

Experimental Demonstration of a Self-organized Architecture for Emerging Grid Computing Applications on OBS Testbed

NASA Astrophysics Data System (ADS)

Liu, Lei; Hong, Xiaobin; Wu, Jian; Lin, Jintong

As Grid computing continues to gain popularity in the industry and research community, it also attracts more attention from the customer level. The large number of users and high frequency of job requests in the consumer market make it challenging. Clearly, all the current Client/Server(C/S)-based architecture will become unfeasible for supporting large-scale Grid applications due to its poor scalability and poor fault-tolerance. In this paper, based on our previous works [1, 2], a novel self-organized architecture to realize a highly scalable and flexible platform for Grids is proposed. Experimental results show that this architecture is suitable and efficient for consumer-oriented Grids.

A highly efficient approach to protein interactome mapping based on collaborative filtering framework.

PubMed

Luo, Xin; You, Zhuhong; Zhou, Mengchu; Li, Shuai; Leung, Hareton; Xia, Yunni; Zhu, Qingsheng

2015-01-09

The comprehensive mapping of protein-protein interactions (PPIs) is highly desired for one to gain deep insights into both fundamental cell biology processes and the pathology of diseases. Finely-set small-scale experiments are not only very expensive but also inefficient to identify numerous interactomes despite their high accuracy. High-throughput screening techniques enable efficient identification of PPIs; yet the desire to further extract useful knowledge from these data leads to the problem of binary interactome mapping. Network topology-based approaches prove to be highly efficient in addressing this problem; however, their performance deteriorates significantly on sparse putative PPI networks. Motivated by the success of collaborative filtering (CF)-based approaches to the problem of personalized-recommendation on large, sparse rating matrices, this work aims at implementing a highly efficient CF-based approach to binary interactome mapping. To achieve this, we first propose a CF framework for it. Under this framework, we model the given data into an interactome weight matrix, where the feature-vectors of involved proteins are extracted. With them, we design the rescaled cosine coefficient to model the inter-neighborhood similarity among involved proteins, for taking the mapping process. Experimental results on three large, sparse datasets demonstrate that the proposed approach outperforms several sophisticated topology-based approaches significantly.

A Highly Efficient Approach to Protein Interactome Mapping Based on Collaborative Filtering Framework

PubMed Central

Luo, Xin; You, Zhuhong; Zhou, Mengchu; Li, Shuai; Leung, Hareton; Xia, Yunni; Zhu, Qingsheng

2015-01-01

The comprehensive mapping of protein-protein interactions (PPIs) is highly desired for one to gain deep insights into both fundamental cell biology processes and the pathology of diseases. Finely-set small-scale experiments are not only very expensive but also inefficient to identify numerous interactomes despite their high accuracy. High-throughput screening techniques enable efficient identification of PPIs; yet the desire to further extract useful knowledge from these data leads to the problem of binary interactome mapping. Network topology-based approaches prove to be highly efficient in addressing this problem; however, their performance deteriorates significantly on sparse putative PPI networks. Motivated by the success of collaborative filtering (CF)-based approaches to the problem of personalized-recommendation on large, sparse rating matrices, this work aims at implementing a highly efficient CF-based approach to binary interactome mapping. To achieve this, we first propose a CF framework for it. Under this framework, we model the given data into an interactome weight matrix, where the feature-vectors of involved proteins are extracted. With them, we design the rescaled cosine coefficient to model the inter-neighborhood similarity among involved proteins, for taking the mapping process. Experimental results on three large, sparse datasets demonstrate that the proposed approach outperforms several sophisticated topology-based approaches significantly. PMID:25572661

A Highly Efficient Approach to Protein Interactome Mapping Based on Collaborative Filtering Framework

NASA Astrophysics Data System (ADS)

Luo, Xin; You, Zhuhong; Zhou, Mengchu; Li, Shuai; Leung, Hareton; Xia, Yunni; Zhu, Qingsheng

2015-01-01

The comprehensive mapping of protein-protein interactions (PPIs) is highly desired for one to gain deep insights into both fundamental cell biology processes and the pathology of diseases. Finely-set small-scale experiments are not only very expensive but also inefficient to identify numerous interactomes despite their high accuracy. High-throughput screening techniques enable efficient identification of PPIs; yet the desire to further extract useful knowledge from these data leads to the problem of binary interactome mapping. Network topology-based approaches prove to be highly efficient in addressing this problem; however, their performance deteriorates significantly on sparse putative PPI networks. Motivated by the success of collaborative filtering (CF)-based approaches to the problem of personalized-recommendation on large, sparse rating matrices, this work aims at implementing a highly efficient CF-based approach to binary interactome mapping. To achieve this, we first propose a CF framework for it. Under this framework, we model the given data into an interactome weight matrix, where the feature-vectors of involved proteins are extracted. With them, we design the rescaled cosine coefficient to model the inter-neighborhood similarity among involved proteins, for taking the mapping process. Experimental results on three large, sparse datasets demonstrate that the proposed approach outperforms several sophisticated topology-based approaches significantly.

Long-term shifts in life-cycle energy efficiency and carbon intensity.

PubMed

Yeh, Sonia; Mishra, Gouri Shankar; Morrison, Geoff; Teter, Jacob; Quiceno, Raul; Gillingham, Kenneth; Riera-Palou, Xavier

2013-03-19

The quantity of primary energy needed to support global human activity is in large part determined by how efficiently that energy is converted to a useful form. We estimate the system-level life-cycle energy efficiency (EF) and carbon intensity (CI) across primary resources for 2005-2100. Our results underscore that although technological improvements at each energy conversion process will improve technology efficiency and lead to important reductions in primary energy use, market mediated effects and structural shifts toward less efficient pathways and pathways with multiple stages of conversion will dampen these efficiency gains. System-level life-cycle efficiency may decrease as mitigation efforts intensify, since low-efficiency renewable systems with high output have much lower GHG emissions than some high-efficiency fossil fuel systems. Climate policies accelerate both improvements in EF and the adoption of renewable technologies, resulting in considerably lower primary energy demand and GHG emissions. Life-cycle EF and CI of useful energy provide a useful metric for understanding dynamics of implementing climate policies. The approaches developed here reiterate the necessity of a combination of policies that target efficiency and decarbonized energy technologies. We also examine life-cycle exergy efficiency (ExF) and find that nearly all of the qualitative results hold regardless of whether we use ExF or EF.

Ultrahigh Error Threshold for Surface Codes with Biased Noise

NASA Astrophysics Data System (ADS)

Tuckett, David K.; Bartlett, Stephen D.; Flammia, Steven T.

2018-02-01

We show that a simple modification of the surface code can exhibit an enormous gain in the error correction threshold for a noise model in which Pauli Z errors occur more frequently than X or Y errors. Such biased noise, where dephasing dominates, is ubiquitous in many quantum architectures. In the limit of pure dephasing noise we find a threshold of 43.7(1)% using a tensor network decoder proposed by Bravyi, Suchara, and Vargo. The threshold remains surprisingly large in the regime of realistic noise bias ratios, for example 28.2(2)% at a bias of 10. The performance is, in fact, at or near the hashing bound for all values of the bias. The modified surface code still uses only weight-4 stabilizers on a square lattice, but merely requires measuring products of Y instead of Z around the faces, as this doubles the number of useful syndrome bits associated with the dominant Z errors. Our results demonstrate that large efficiency gains can be found by appropriately tailoring codes and decoders to realistic noise models, even under the locality constraints of topological codes.

Discontinuous Galerkin Methods and High-Speed Turbulent Flows

NASA Astrophysics Data System (ADS)

Atak, Muhammed; Larsson, Johan; Munz, Claus-Dieter

2014-11-01

Discontinuous Galerkin methods gain increasing importance within the CFD community as they combine arbitrary high order of accuracy in complex geometries with parallel efficiency. Particularly the discontinuous Galerkin spectral element method (DGSEM) is a promising candidate for both the direct numerical simulation (DNS) and large eddy simulation (LES) of turbulent flows due to its excellent scaling attributes. In this talk, we present a DNS of a compressible turbulent boundary layer along a flat plate at a free-stream Mach number of M = 2.67 and assess the computational efficiency of the DGSEM at performing high-fidelity simulations of both transitional and turbulent boundary layers. We compare the accuracy of the results as well as the computational performance to results using a high order finite difference method.

Components for monolithic fiber chirped pulse amplification laser systems

NASA Astrophysics Data System (ADS)

Swan, Michael Craig

The first portion of this work develops techniques for generating femtosecond-pulses from conventional fabry-perot laser diodes using nonlinear-spectral-broadening techniques in Yb-doped positive dispersion fiber ampliers. The approach employed an injection-locked fabry-perot laser diode followed by two stages of nonlinear-spectral-broadening to generate sub-200fs pulses. This thesis demonstrated that a 60ps gain-switched fabry-perot laser-diode can be injection-locked to generate a single-longitudinal-mode pulse and compressed by nonlinear spectral broadening to 4ps. Two problems have been identified that must be resolved before moving forward with this approach. First, gain-switched pulses from a standard diode-laser have a number of characteristics not well suited for producing clean self-phase-modulation-broadened pulses, such as an asymmetric temporal shape, which has a long pulse tail. Second, though parabolic pulse formation occurs for any arbitrary temporal input pulse profile, deviation from the optimum parabolic input results in extensively spectrally modulated self-phase-modulation-broadened pulses. In conclusion, the approach of generating self-phase-modulation-broadened pulses from pulsed laser diodes has to be modified from the initial approach explored in this thesis. The first Yb-doped chirally-coupled-core ber based systems are demonstrated and characterized in the second portion of this work. Robust single-mode performance independent of excitation or any other external mode management techniques have been demonstrated in Yb-doped chirally-coupled-core fibers. Gain and power efficiency characteristics are not compromised in any way in this novel fiber structure up to the 87W maximum power achieved. Both the small signal gain at 1064nm of 30.3dB, and the wavelength dependence of the small signal gain were comparable to currently deployed large-mode-area-fiber technology. The efficiencies of the laser and amplifier were measured to be 75% and 54% respectively. With the inherent design tradeoff between the fundamental mode loss and higher order mode suppression, loss effects on system efficiency in different configurations were investigated. From these investigations it was seen that the slope-efficiency depends only on the total loss of the active fiber, and that when loss is present, the counter-propagating configuration has substantial advantages over the co-propagating case. In this thesis chirally-coupled-core fiber as the technological basis for the next generation of monolithic high power fiber laser systems has been established.

MEERCAT: Multiplexed Efficient Cell Free Expression of Recombinant QconCATs For Large Scale Absolute Proteome Quantification*

PubMed Central

Takemori, Nobuaki; Takemori, Ayako; Tanaka, Yuki; Endo, Yaeta; Hurst, Jane L.; Gómez-Baena, Guadalupe; Harman, Victoria M.; Beynon, Robert J.

2017-01-01

A major challenge in proteomics is the absolute accurate quantification of large numbers of proteins. QconCATs, artificial proteins that are concatenations of multiple standard peptides, are well established as an efficient means to generate standards for proteome quantification. Previously, QconCATs have been expressed in bacteria, but we now describe QconCAT expression in a robust, cell-free system. The new expression approach rescues QconCATs that previously were unable to be expressed in bacteria and can reduce the incidence of proteolytic damage to QconCATs. Moreover, it is possible to cosynthesize QconCATs in a highly-multiplexed translation reaction, coexpressing tens or hundreds of QconCATs simultaneously. By obviating bacterial culture and through the gain of high level multiplexing, it is now possible to generate tens of thousands of standard peptides in a matter of weeks, rendering absolute quantification of a complex proteome highly achievable in a reproducible, broadly deployable system. PMID:29055021

An efficient and reliable predictive method for fluidized bed simulation

DOE PAGES

Lu, Liqiang; Benyahia, Sofiane; Li, Tingwen

2017-06-13

In past decades, the continuum approach was the only practical technique to simulate large-scale fluidized bed reactors because discrete approaches suffer from the cost of tracking huge numbers of particles and their collisions. This study significantly improved the computation speed of discrete particle methods in two steps: First, the time-driven hard-sphere (TDHS) algorithm with a larger time-step is proposed allowing a speedup of 20-60 times; second, the number of tracked particles is reduced by adopting the coarse-graining technique gaining an additional 2-3 orders of magnitude speedup of the simulations. A new velocity correction term was introduced and validated in TDHSmore » to solve the over-packing issue in dense granular flow. The TDHS was then coupled with the coarse-graining technique to simulate a pilot-scale riser. The simulation results compared well with experiment data and proved that this new approach can be used for efficient and reliable simulations of large-scale fluidized bed systems.« less

An efficient and reliable predictive method for fluidized bed simulation

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

Lu, Liqiang; Benyahia, Sofiane; Li, Tingwen

2017-06-29

In past decades, the continuum approach was the only practical technique to simulate large-scale fluidized bed reactors because discrete approaches suffer from the cost of tracking huge numbers of particles and their collisions. This study significantly improved the computation speed of discrete particle methods in two steps: First, the time-driven hard-sphere (TDHS) algorithm with a larger time-step is proposed allowing a speedup of 20-60 times; second, the number of tracked particles is reduced by adopting the coarse-graining technique gaining an additional 2-3 orders of magnitude speedup of the simulations. A new velocity correction term was introduced and validated in TDHSmore » to solve the over-packing issue in dense granular flow. The TDHS was then coupled with the coarse-graining technique to simulate a pilot-scale riser. The simulation results compared well with experiment data and proved that this new approach can be used for efficient and reliable simulations of large-scale fluidized bed systems.« less

Strategies for implementing genomic selection for feed efficiency in dairy cattle breeding schemes.

PubMed

Wallén, S E; Lillehammer, M; Meuwissen, T H E

2017-08-01

Alternative genomic selection and traditional BLUP breeding schemes were compared for the genetic improvement of feed efficiency in simulated Norwegian Red dairy cattle populations. The change in genetic gain over time and achievable selection accuracy were studied for milk yield and residual feed intake, as a measure of feed efficiency. When including feed efficiency in genomic BLUP schemes, it was possible to achieve high selection accuracies for genomic selection, and all genomic BLUP schemes gave better genetic gain for feed efficiency than BLUP using a pedigree relationship matrix. However, introducing a second trait in the breeding goal caused a reduction in the genetic gain for milk yield. When using contracted test herds with genotyped and feed efficiency recorded cows as a reference population, adding an additional 4,000 new heifers per year to the reference population gave accuracies that were comparable to a male reference population that used progeny testing with 250 daughters per sire. When the test herd consisted of 500 or 1,000 cows, lower genetic gain was found than using progeny test records to update the reference population. It was concluded that to improve difficult to record traits, the use of contracted test herds that had additional recording (e.g., measurements required to calculate feed efficiency) is a viable option, possibly through international collaborations. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Fuel-Cell-Powered Electric Motor Drive Analyzed for a Large Airplane

NASA Technical Reports Server (NTRS)

Brown, Gerald V.; Choi, Benjamin B.

2005-01-01

Because of its high efficiency, fuel cell technology may be used to launch a new generation of more-electric aeropropulsion and power systems for future aircraft. Electric-motor-driven airplanes using fuel-cell powerplants would be beneficial to the environment because of fuel savings, low noise, and zero carbon-dioxide emissions. In spite of the fuel cell s efficiency benefit, to produce the same shaft drive power, a fuel cell- powered electric-drive system must be definitely heavier than a turbine-drive system. However, the fuel-cell system s overall efficiency from fuel-to-shaft power is higher than for a turbine-drive system. This means that the fuel consumption rate could be lower than for a conventional system. For heavier, fuel-laden planes for longer flights, we might achieve substantial fuel savings. In the airplane industry, in fact, an efficiency gain of even a few percentage points can make a major economic difference in operating costs.

Comparative Study of DC and AC Microgrids in Commercial Buildings Across Different Climates and Operating Profiles

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

Fregosi, Daniel; Ravula, Sharmila; Brhlik, Dusan

2015-06-07

Bosch has developed and demonstrated a novel direct current (DC) microgrid system that maximizes the efficiency of locally generated photovoltaic energy while offering high reliability, safety, redundancy, and reduced cost compared to equivalent alternating current (AC) systems. Several demonstration projects validating the system feasibility and expected efficiency gains have been completed and additional ones are in progress. This paper gives an overview of the Bosch DC microgrid system and presents key results from a large simulation study done to estimate the energy savings of the Bosch DC microgrid over conventional AC systems. The study examined the system performance in locationsmore » across the United States for several commercial building types and operating profiles. It found that the Bosch DC microgrid uses generated PV energy 6%-8% more efficiently than traditional AC systems.« less

Solar-pumped gas laser development

NASA Technical Reports Server (NTRS)

Wilson, J. W.

1980-01-01

A survey of gas properties through detailed kinetic models led to the identification of critical gas parameters for use in choosing appropriate gas combinations for solar pumped lasers. Broadband photoabsorption in the visible or near UV range is required to excite large volumes of gas and to insure good solar absorption efficiency. The photoexcitation density is independent of the absorption bandwidth. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than 10 A to insure lasing threshold over reasonable gain lengths. The system should show a high degree of chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. Although photoexcitation of electronic vibrational transitions is considered as a possible system if the emission bands sufficiently narrow, it appears that photodissociation into atomic metastables is more likely to result in a successful solar pumped laser system.

Wireless energy transfer: Dielectric lens antennas for beam shaping in wireless power-transfer applications

NASA Astrophysics Data System (ADS)

Gonçalves, Ricardo; Carvalho, Nuno B.; Pinho, Pedro

2017-02-01

In the current contest of wireless systems, the last frontier remains the cut of the power cord. In that sense, the interest over wireless energy transfer technologies in the past years has grown exponentially. However, there are still many challenges to be overcome in order to enable wireless energy transfer full potential. One of the focus in the development of such systems is the design of very-high-gain, highly efficient, antennas that can compensate for the propagation loss of radio signals over the air. In this paper, we explore the design and manufacturing process of dielectric lenses, fabricated using a professional-grade desktop 3D printer. Lens antennas are used in order to increase beam efficiency and therefore maximize the efficiency of a wireless power-transfer system operating at microwave frequencies in the Ku band. Measurements of two fabricated prototypes showcase a large directivity, as predicted with simulations. xml:lang="fr"

Commercial Buck Converters and Custom Coil Development for the ATLAS Inner Detector Upgrade

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

Dhawan, S.; Lanni, F.; Baker, O.

2010-04-01

A new generation of higher gain commercial buck converters built using advanced short channel CMOS processes has the potential to operate in the Atlas Inner Detector at the Super Large Hadron Collider (sLHC). This approach would inherently be more efficient than the existing practice of locating the power conversion external to the detector. The converters must operate in a large magnetic field and be able to survive both high doses of ionizing radiation and large neutron fluences. The presence of a large magnetic field necessitates the use of an air core inductor which is developed and discussed here. Noise measurementsmore » will be made to investigate the effect of the high frequency switching of the buck converter on the sensitive front end electronics. Radiation hardness of selected buck converters and mosfets will also be reported.« less

Energy and protein feed-to-food conversion efficiencies in the US and potential food security gains from dietary changes

NASA Astrophysics Data System (ADS)

Shepon, A.; Eshel, G.; Noor, E.; Milo, R.

2016-10-01

Feeding a growing population while minimizing environmental degradation is a global challenge requiring thoroughly rethinking food production and consumption. Dietary choices control food availability and natural resource demands. In particular, reducing or avoiding consumption of low production efficiency animal-based products can spare resources that can then yield more food. In quantifying the potential food gains of specific dietary shifts, most earlier research focused on calories, with less attention to other important nutrients, notably protein. Moreover, despite the well-known environmental burdens of livestock, only a handful of national level feed-to-food conversion efficiency estimates of dairy, beef, poultry, pork, and eggs exist. Yet such high level estimates are essential for reducing diet related environmental impacts and identifying optimal food gain paths. Here we quantify caloric and protein conversion efficiencies for US livestock categories. We then use these efficiencies to calculate the food availability gains expected from replacing beef in the US diet with poultry, a more efficient meat, and a plant-based alternative. Averaged over all categories, caloric and protein efficiencies are 7%-8%. At 3% in both metrics, beef is by far the least efficient. We find that reallocating the agricultural land used for beef feed to poultry feed production can meet the caloric and protein demands of ≈120 and ≈140 million additional people consuming the mean American diet, respectively, roughly 40% of current US population.

Cecum microbial communities from steers differing in feed efficiency

USDA-ARS?s Scientific Manuscript database

Aims: To characterize the microbial communities of the cecum among steers differing in feed efficiency. Methods and Results: Individual feed intake (FI) and body weight (BW) gain were determined from animals fed the same ration, within two contemporary groups of steers. BW gain was regressed on F...

TU-AB-BRC-07: Efficiency of An IAEA Phase-Space Source for a Low Energy X-Ray Tube Using Egs++

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

Watson, PGF; Renaud, MA; Seuntjens, J

Purpose: To extend the capability of the EGSnrc C++ class library (egs++) to write and read IAEA phase-space files as a particle source, and to assess the relative efficiency gain in dose calculation using an IAEA phase-space source for modelling a miniature low energy x-ray source. Methods: We created a new ausgab object to score particles exiting a user-defined geometry and write them to an IAEA phase-space file. A new particle source was created to read from IAEA phase-space data. With these tools, a phase-space file was generated for particles exiting a miniature 50 kVp x-ray tube (The INTRABEAM System,more » Carl Zeiss). The phase-space source was validated by comparing calculated PDDs with a full electron source simulation of the INTRABEAM. The dose calculation efficiency gain of the phase-space source was determined relative to the full simulation. The efficiency gain as a function of i) depth in water, and ii) job parallelization was investigated. Results: The phase-space and electron source PDDs were found to agree to 0.5% RMS, comparable to statistical uncertainties. The use of a phase-space source for the INTRABEAM led to a relative efficiency gain of greater than 20 over the full electron source simulation, with an increase of up to a factor of 196. The efficiency gain was found to decrease with depth in water, due to the influence of scattering. Job parallelization (across 2 to 256 cores) was not found to have any detrimental effect on efficiency gain. Conclusion: A set of tools has been developed for writing and reading IAEA phase-space files, which can be used with any egs++ user code. For simulation of a low energy x-ray tube, the use of a phase-space source was found to increase the relative dose calculation efficiency by factor of up to 196. The authors acknowledge partial support by the CREATE Medical Physics Research Training Network grant of the Natural Sciences and Engineering Research Council (Grant No. 432290).« less

Elimination of resistive losses in large-area LEDs by new diffusion-driven devices

NASA Astrophysics Data System (ADS)

Kivisaari, Pyry; Kim, Iurii; Suihkonen, Sami; Oksanen, Jani

2017-02-01

High-power operation of conventional GaN-based light-emitting diodes (LEDs) is severely limited by current crowding, which increases the bias voltage of the LED, concentrates light emission close to the p-type contact edge, and aggravates the efficiency droop. Fabricating LEDs on thick n-GaN substrates alleviates current crowding but requires the use of expensive bulk GaN substrates and fairly large n-contacts, which take away a large part of the active region (AR). In this work, we demonstrate through comparative simulations how the recently introduced diffusion-driven charge transport (DDCT) concept can be used to realize lateral heterojunction (LHJ) structures, which eliminate most of the lateral current crowding. Specifically in this work, we analyze how using a single-side graded AR can both facilitate electron and hole diffusion in DDCT and increase the effective AR thickness. Our simulations show that the increased effective AR thickness allows a substantial reduction in the efficiency droop at large currents, and that unlike conventional 2D LEDs, the LHJ structure shows practically no added efficiency loss or differential resistance due to current crowding. Furthermore, as both electrons and holes enter the AR from the same side without any notable potential barriers in the LHJ structure, the LHJ structure shows an additional wall-plug efficiency gain over the conventional structures under comparison. This injection from the same side is expected to be even more interesting in multiple quantum well structures, where carriers typically need to surpass several potential barriers in conventional LEDs before recombining. In addition to simulations, we also demonstrate selective-area growth of a finger structure suitable for operation as an LHJ device with 2µm distance between n- and p-GaN regions.

Window Glazing Types | Efficient Windows Collaborative

Science.gov Websites

of glass. Single Clear Single Tint Double Glazing The following sections on high-performance double fills. Double Clear Double Tint Double High-Solar-Gain Low-E Double Medium-Solar-Gain Low-E Double Low -Solar-Gain Low-E Double High-Solar-Gain Low-E with Roomside (4th surface) Low-E Double Medium-Solar-Gain

Do Generous Welfare States Generate Efficiency Gains Which Counterbalance Short Run Losses? Testing Downside Risk Theory with Economic Panel Data for the U.S., Germany and the Netherlands

ERIC Educational Resources Information Center

Headey, Bruce; Muffels, Ruud

2008-01-01

The purpose of the paper is to assess the theory that the downside risk insurance provided by more generous welfare states generates long run efficiency gains, which counterbalance the short run efficiency losses caused by work disincentives in these states (Feldstein 1974, 1976; Sinn 1995, 1996). Testing downside risk theory requires long term…

Biophysical and economic water productivity of dual-purpose cattle farming.

PubMed

Sraïri, M T; Benjelloun, R; Karrou, M; Ates, S; Kuper, M

2016-02-01

This study analyzes key factors influencing water productivity in cattle rearing, particularly in contexts characterized by water scarcity. This was done through year-round monitoring of on-farm practices within five smallholder farms located in the Saïss area (northern Morocco). The on-farm monitoring protocol consisted of characterizing: (i) volumes of water used for fodder production and distinguished by source (rainfall, surface irrigation and groundwater), (ii) virtual water contained in off-farm feed resources, (iii) total forage biomass production, (iv) dietary rations fed to lactating cows and their calves and (v) milk output and live weight gain. Findings reveal a mean water footprint of 1.62±0.81 and 8.44±1.09 m3/kg of milk and of live weight gain, respectively. Groundwater represented only 13.1% and 2.2% of the total water used to get milk and live weight gain, respectively, while rainfall represented 53.0% and 48.1% of the total water for milk and live weight gain, respectively. The remaining water volumes used came from surface irrigation water (7.4% for milk and 4.0% for live weight gain) and from virtual water (26.5% for milk and 44.7% for live weight gain). The results also revealed a relatively small gross margin per m3 of water used by the herd, not exceeding an average value of US $ 0.05, when considering both milk and live weight. Given the large variability in farm performances, which affect water productivity in cattle rearing throughout the production process, we highlight the potential for introducing a series of interventions that are aimed at saving water, while concurrently improving efficiency in milk production and live weight gain. These interventions should target the chain of production functions that are implemented throughout the process of water productivity in cattle rearing. Moreover, these interventions are of particular importance given our findings that livestock production depends largely upon rainfall, rather than groundwater, in an area afflicted with sustained droughts, overexploitation of groundwater resources and growing water scarcity.

Using the entire history in the analysis of nested case cohort samples.

PubMed

Rivera, C L; Lumley, T

2016-08-15

Countermatching designs can provide more efficient estimates than simple matching or case-cohort designs in certain situations such as when good surrogate variables for an exposure of interest are available. We extend pseudolikelihood estimation for the Cox model under countermatching designs to models where time-varying covariates are considered. We also implement pseudolikelihood with calibrated weights to improve efficiency in nested case-control designs in the presence of time-varying variables. A simulation study is carried out, which considers four different scenarios including a binary time-dependent variable, a continuous time-dependent variable, and the case including interactions in each. Simulation results show that pseudolikelihood with calibrated weights under countermatching offers large gains in efficiency if compared to case-cohort. Pseudolikelihood with calibrated weights yielded more efficient estimators than pseudolikelihood estimators. Additionally, estimators were more efficient under countermatching than under case-cohort for the situations considered. The methods are illustrated using the Colorado Plateau uranium miners cohort. Furthermore, we present a general method to generate survival times with time-varying covariates. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Multi-stage decoding for multi-level block modulation codes

NASA Technical Reports Server (NTRS)

Lin, Shu

1991-01-01

In this paper, we investigate various types of multi-stage decoding for multi-level block modulation codes, in which the decoding of a component code at each stage can be either soft-decision or hard-decision, maximum likelihood or bounded-distance. Error performance of codes is analyzed for a memoryless additive channel based on various types of multi-stage decoding, and upper bounds on the probability of an incorrect decoding are derived. Based on our study and computation results, we find that, if component codes of a multi-level modulation code and types of decoding at various stages are chosen properly, high spectral efficiency and large coding gain can be achieved with reduced decoding complexity. In particular, we find that the difference in performance between the suboptimum multi-stage soft-decision maximum likelihood decoding of a modulation code and the single-stage optimum decoding of the overall code is very small: only a fraction of dB loss in SNR at the probability of an incorrect decoding for a block of 10(exp -6). Multi-stage decoding of multi-level modulation codes really offers a way to achieve the best of three worlds, bandwidth efficiency, coding gain, and decoding complexity.

Fast Bayesian experimental design: Laplace-based importance sampling for the expected information gain

NASA Astrophysics Data System (ADS)

Beck, Joakim; Dia, Ben Mansour; Espath, Luis F. R.; Long, Quan; Tempone, Raúl

2018-06-01

In calculating expected information gain in optimal Bayesian experimental design, the computation of the inner loop in the classical double-loop Monte Carlo requires a large number of samples and suffers from underflow if the number of samples is small. These drawbacks can be avoided by using an importance sampling approach. We present a computationally efficient method for optimal Bayesian experimental design that introduces importance sampling based on the Laplace method to the inner loop. We derive the optimal values for the method parameters in which the average computational cost is minimized according to the desired error tolerance. We use three numerical examples to demonstrate the computational efficiency of our method compared with the classical double-loop Monte Carlo, and a more recent single-loop Monte Carlo method that uses the Laplace method as an approximation of the return value of the inner loop. The first example is a scalar problem that is linear in the uncertain parameter. The second example is a nonlinear scalar problem. The third example deals with the optimal sensor placement for an electrical impedance tomography experiment to recover the fiber orientation in laminate composites.

Quantum computation and analysis of Wigner and Husimi functions: toward a quantum image treatment.

PubMed

Terraneo, M; Georgeot, B; Shepelyansky, D L

2005-06-01

We study the efficiency of quantum algorithms which aim at obtaining phase-space distribution functions of quantum systems. Wigner and Husimi functions are considered. Different quantum algorithms are envisioned to build these functions, and compared with the classical computation. Different procedures to extract more efficiently information from the final wave function of these algorithms are studied, including coarse-grained measurements, amplitude amplification, and measure of wavelet-transformed wave function. The algorithms are analyzed and numerically tested on a complex quantum system showing different behavior depending on parameters: namely, the kicked rotator. The results for the Wigner function show in particular that the use of the quantum wavelet transform gives a polynomial gain over classical computation. For the Husimi distribution, the gain is much larger than for the Wigner function and is larger with the help of amplitude amplification and wavelet transforms. We discuss the generalization of these results to the simulation of other quantum systems. We also apply the same set of techniques to the analysis of real images. The results show that the use of the quantum wavelet transform allows one to lower dramatically the number of measurements needed, but at the cost of a large loss of information.

Shift in a Large River Fish Assemblage: Body-Size and Trophic Structure Dynamics

PubMed Central

Broadway, Kyle J.; Pyron, Mark; Gammon, James R.; Murry, Brent A.

2015-01-01

As the intensity and speed of environmental change increase at both local and global scales it is imperative that we gain a better understanding of the ecological implications of community shifts. While there has been substantial progress toward understanding the drivers and subsequent responses of community change (e.g. lake trophic state), the ecological impacts of food web changes are far less understood. We analyzed Wabash River fish assemblage data collected from 1974-2008, to evaluate temporal variation in body-size structure and functional group composition. Two parameters derived from annual community size-spectra were our major response variables: (1) the regression slope is an index of ecological efficiency and predator-prey biomass ratios, and (2) spectral elevation (regression midpoint height) is a proxy for food web capacity. We detected a large assemblage shift, over at least a seven year period, defined by dramatic changes in abundance (measured as catch-per-unit-effort) of the dominant functional feeding groups among two time periods; from an assemblage dominated by planktivore-omnivores to benthic invertivores. There was a concurrent increase in ecological efficiency (slopes increased over time) following the shift associated with an increase in large-bodied low trophic level fish. Food web capacity remained relatively stable with no clear temporal trends. Thus, increased ecological efficiency occurred simultaneous to a compensatory response that shifted biomass among functional feeding groups. PMID:25902144

Studies of uniformity of 50 μm low-gain avalanche detectors at the Fermilab test beam

NASA Astrophysics Data System (ADS)

Apresyan, A.; Xie, S.; Pena, C.; Arcidiacono, R.; Cartiglia, N.; Carulla, M.; Derylo, G.; Ferrero, M.; Flores, D.; Freeman, P.; Galloway, Z.; Ghassemi, A.; Al Ghoul, H.; Gray, L.; Hidalgo, S.; Kamada, S.; Los, S.; Mandurrino, M.; Merlos, A.; Minafra, N.; Pellegrini, G.; Quirion, D.; Ronzhin, A.; Royon, C.; Sadrozinski, H.; Seiden, A.; Sola, V.; Spiropulu, M.; Staiano, A.; Uplegger, L.; Yamamoto, K.; Yamamura, K.

2018-07-01

In this paper we report measurements of the uniformity of time resolution, signal amplitude, and charged particle detection efficiency across the sensor surface of low-gain avalanche detectors (LGAD). Comparisons of the performance of sensors with different doping concentrations and different active thicknesses are presented, as well as their temperature dependence and radiation tolerance up to 6 × 1014 n/cm2. Results were obtained at the Fermilab test beam facility using 120 GeV proton beams, and a high precision pixel tracking detector. LGAD sensors manufactured by the Centro Nacional de Microelectrónica (CNM) and Hamamatsu Photonics (HPK) were studied. The uniformity of the sensor response in pulse height before irradiation was found to have a 2% spread. The signal detection efficiency and timing resolution in the sensitive areas before irradiation were found to be 100% and 30-40 ps, respectively. A "no-response" area between pads was measured to be about 130 μm for CNM and 170 μm for HPK sensors. After a neutron fluence of 6 × 1014 n/cm2 the CNM sensor exhibits a large gain variation of up to a factor of 2.5 when comparing metalized and non-metalized sensor areas. An irradiated CNM sensor achieved a time resolution of 30 ps for the metalized area and 40 ps for the non-metalized area, while a HPK sensor irradiated to the same fluence achieved a 30 ps time resolution.

Array feed synthesis for correction of reflector distortion and Vernier beamsteering

NASA Technical Reports Server (NTRS)

Blank, Stephen J.; Imbriale, William A.

1988-01-01

An algorithmic procedure for the synthesis of planar array feeds for paraboloidal reflectors is described which simultaneously provides electronic correction of systematic reflector surface distortions as well as a Vernier electronic beamsteering capability. Simple rules of thumb for the optimum chioce of planar array feed configuration (i.e., the number and type of elements) are derived from a parametric study made using the synthesis procedure. A number of f/D ratios and distortion models were examined that are typical of large paraboloidal reflectors. Numerical results are presented showing that, for the range of distortion models considered, good on-axis gain restoration can be achieved with as few as seven elements. For beamsteering to +/- 1 beamwidth (BW), 19 elements are required. For arrays with either 7 or 19 elements, the results indicate that the use of high-aperture-efficiency elements (e.g., disk-on-rod and short backfire) in the array yields higher system gain than can be obtained with elements having lower aperture efficiency (e.g., open-ended waveguides). With 37 elements, excellent gain and beamsteering performance to +/- 1.5 BW are obtained independent of the assumed effective aperture of the array element. An approximate expression is derived for the focal-plane field distribution of the distorted reflector. Contour plots of the focal-plane fields are also presented for various distortion and beam scan angle cases. The results obtained show the effectiveness of the array feed approach.

A factor involved in efficient breakdown of supersonic streamwise vortices

NASA Astrophysics Data System (ADS)

Hiejima, Toshihiko

2015-03-01

Spatially developing processes in supersonic streamwise vortices were numerically simulated at Mach number 5.0. The vortex evolution largely depended on the azimuthal vorticity thickness of the vortices, which governs the negative helicity profile. Large vorticity thickness greatly enhanced the centrifugal instability, with consequent development of perturbations with competing wavenumbers outside the vortex core. During the transition process, supersonic streamwise vortices could generate large-scale spiral structures and a number of hairpin like vortices. Remarkably, the transition caused a dramatic increase in the total fluctuation energy of hypersonic flows, because the negative helicity profile destabilizes the flows due to helicity instability. Unstable growth might also relate to the correlation length between the axial and azimuthal vorticities of the streamwise vortices. The knowledge gained in this study is important for realizing effective fuel-oxidizer mixing in supersonic combustion engines.

Visual attention mitigates information loss in small- and large-scale neural codes.

PubMed

Sprague, Thomas C; Saproo, Sameer; Serences, John T

2015-04-01

The visual system transforms complex inputs into robust and parsimonious neural codes that efficiently guide behavior. Because neural communication is stochastic, the amount of encoded visual information necessarily decreases with each synapse. This constraint requires that sensory signals are processed in a manner that protects information about relevant stimuli from degradation. Such selective processing--or selective attention--is implemented via several mechanisms, including neural gain and changes in tuning properties. However, examining each of these effects in isolation obscures their joint impact on the fidelity of stimulus feature representations by large-scale population codes. Instead, large-scale activity patterns can be used to reconstruct representations of relevant and irrelevant stimuli, thereby providing a holistic understanding about how neuron-level modulations collectively impact stimulus encoding. Copyright © 2015 Elsevier Ltd. All rights reserved.

A semiparametric graphical modelling approach for large-scale equity selection.

PubMed

Liu, Han; Mulvey, John; Zhao, Tianqi

2016-01-01

We propose a new stock selection strategy that exploits rebalancing returns and improves portfolio performance. To effectively harvest rebalancing gains, we apply ideas from elliptical-copula graphical modelling and stability inference to select stocks that are as independent as possible. The proposed elliptical-copula graphical model has a latent Gaussian representation; its structure can be effectively inferred using the regularized rank-based estimators. The resulting algorithm is computationally efficient and scales to large data-sets. To show the efficacy of the proposed method, we apply it to conduct equity selection based on a 16-year health care stock data-set and a large 34-year stock data-set. Empirical tests show that the proposed method is superior to alternative strategies including a principal component analysis-based approach and the classical Markowitz strategy based on the traditional buy-and-hold assumption.

Electron Shock Ignition of Inertial Fusion Targets

DOE PAGES

Shang, W. L.; Betti, R.; Hu, S. X.; ...

2017-11-07

Here, it is shown that inertial fusion targets designed with low implosion velocities can be shock ignited using laser–plasma interaction generated hot electrons (hot-e) to obtain high-energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e, which can only be produced on a large laser facility like the National Ignition Facility, with the laser to hot-e conversion efficiency greater than 10% at laser intensities ~10 16 W/cm 2.

Needleless Electrospinning of Pure and Blended Chitosan

NASA Astrophysics Data System (ADS)

Grimmelsmann, Nils; Homburg, Sarah Vanessa; Ehrmann, Andrea

2017-08-01

Chitosan is a biopolymer with bactericidal, fungicidal, hemostatic and other interesting properties. It can be used, e.g., in medical products, as a filter medium, in biotechnological purposes etc. For these possible applications, nanofiber mats with a large inner surface will be most efficient. This is why in a recent project, the electrospinning properties of pure chitosan as well as chitosan blended with poly(ethylene oxide) were investigated. Using a needleless nanospinning process, the technology under examination can be upscaled from lab to industrial scale, enabling direct transfer of the gained experiences to the intended application.

Electron Shock Ignition of Inertial Fusion Targets

NASA Astrophysics Data System (ADS)

Shang, W. L.; Betti, R.; Hu, S. X.; Woo, K.; Hao, L.; Ren, C.; Christopherson, A. R.; Bose, A.; Theobald, W.

2017-11-01

It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-e 's) to obtain high energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e 's which can be produced only at a large laser facility like the National Ignition Facility, with the laser-to-hot-e conversion efficiency greater than 10% at laser intensities ˜1016 W /cm2 .

Electron Shock Ignition of Inertial Fusion Targets.

PubMed

Shang, W L; Betti, R; Hu, S X; Woo, K; Hao, L; Ren, C; Christopherson, A R; Bose, A; Theobald, W

2017-11-10

It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-e's) to obtain high energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e's which can be produced only at a large laser facility like the National Ignition Facility, with the laser-to-hot-e conversion efficiency greater than 10% at laser intensities ∼10^{16}  W/cm^{2}.

Short-term benefits from central unit commitment and dispatch: Application to the Southern African Power Pool

NASA Astrophysics Data System (ADS)

Bowen, Brian Hugh

1998-12-01

Electricity utilities in the Southern African region are conscious that gains could be made from more economically efficient trading but have had no tools with which to analyze the effects of a change in policy. This research is the first to provide transparent quantitative techniques to quantify the impacts of new trading arrangements in this region. The study poses a model of the recently formed Southern African Power Pool, built with the collaboration of the region's national utilities to represent each country's demand and generation/transmission system. The multi-region model includes commitment and dispatch from diverse hydrothermal sources over a vast area. Economic gains are determined by comparing the total costs under free-trade conditions with those from the existing fixed-trade bilateral arrangements. The objective function minimizes production costs needed to meet total demand, subject to each utility's constraints for thermal and hydro generation, transmission, load balance and losses. Linearized thermal cost functions are used along with linearized input output hydropower plant curves and hydrothermal on/off status variables to formulate a mixed-integer programming problem. Results from the modeling show that moving to optimal trading patterns could save between 70 million and 130 million per year. With free-trade policies the quantity of power flow between utilities is doubled and maximum usage is made of the hydropower stations thus reducing costs and fuel use. In electricity exporting countries such as Zambia and Mozambique gains from increased trade are achieved which equal 16% and 18% respectively of the value of their total manufactured exports. A sensitivity analysis is conducted on the possible effects of derating generation, derating transmission and reducing water inflows but gains remain large. Maximum economic gains from optimal trading patterns can be achieved by each country allowing centralized control through the newly founded SAPP coordination center. Using standard mixed integer programming solvers makes the cost of such modeling activity easily affordable to each utility in the Southern African pool. This research provides the utilities with the modeling tools to quantify the gains from increased trade and thereby furthers a move towards greater efficiency, faster economic growth and reduced use of fossil fuels.

Phenotypic and Genetic Correlations of Feed Efficiency Traits with Growth and Carcass Traits in Nellore Cattle Selected for Postweaning Weight.

PubMed

Ceacero, Thais Matos; Mercadante, Maria Eugênia Zerlotti; Cyrillo, Joslaine Noely Dos Santos Gonçalves; Canesin, Roberta Carrilho; Bonilha, Sarah Figueiredo Martins; de Albuquerque, Lucia Galvão

2016-01-01

This study evaluated phenotypic (rph) and genetic correlations (rg) between 8 feed efficiency traits and other traits of economic interest including weight at selection (WS), loin-eye area (LEA), backfat thickness (BF), and rump fat thickness (RF) in Nellore cattle. Feed efficiency traits were gain:feed, residual feed intake (RFI), residual feed intake adjusted for backfat thickness (RFIb) and for backfat and rump fat thickness (RFIsf), residual body weight gain (RG), residual intake and body weight gain (RIG), and residual intake and body weight gain using RFIb (RIGb) and RFIsf (RIGsf). The variance components were estimated by the restricted maximum likelihood method using a two-trait animal model. The heritability estimates (h2) were 0.14, 0.24, 0.20, 0.22, 0.19, 0.15, 0.11 and 0.11 for gain:feed, RFI, RFIb, RFIsf, RG, RIG, RIGb and RIGsf, respectively. All rph values between traits were close to zero, except for the correlation of feed efficiency traits with dry matter intake and average daily gain. High rg values were observed for the correlation of dry matter intake, average daily gain and metabolic weight with WS and hip height (>0.61) and low to medium values (0.15 to 0.48) with the carcass traits (LEA, BF, RF). Among the feed efficiency traits, RG showed the highest rg with WS and hip height (0.34 and 0.25) and the lowest rg with subcutaneous fat thickness (-0.17 to 0.18). The rg values of RFI, RFIb and RFIsf with WS (0.17, 0.23 and 0.22), BF (0.37, 0.33 and 0.33) and RF (0.30, 0.31 and 0.32) were unfavorable. The rg values of gain:feed, RIG, RIGb and RIGsf with WS were low and favorable (0.07 to 0.22), while medium and unfavorable (-0.22 to -0.45) correlations were observed with fat thickness. The inclusion of subcutaneous fat thickness in the models used to calculate RFI did not reduce the rg between these traits. Selecting animals for higher feed efficiency will result in little or no genetic change in growth and will decrease subcutaneous fat thickness in the carcass.

Spectral gain measurements of quantum confined emitters, and design and fabrication of intersubband quantum box laser structures

NASA Astrophysics Data System (ADS)

Tsvid, Gene

Semiconductor laser active regions are commonly characterized by photo- and electro-luminescence (PL, EL) and cavity length analysis. However quantitative spectral information is not readily extracted from PL and EL data and comparison of different active region materials can be difficult. More quantifiable spectral information is contained in the optical gain spectra. This work reports on spectral gain studies, using multi-segmented interband devices, of InGaAs quantum well and quantum dot active regions grown by metalorganic chemical vapor deposition (MOCVD). Using the fundamental connection between gain and spontaneous emission spectra, the spontaneous radiative current and spontaneous radiative efficiency is evaluated for these active regions. The spectral gain and spontaneous radiative efficiency measurements of 980 nm emitting InGaAs quantum well (QW) material provides a benchmark comparison to previous results obtained on highly-strained, 1200 nm emitting InGaAs QW material. These studies provide insight into carrier recombination and the role of the current injection efficiency in InGaAs QW lasers. The spectral gain of self-assembled MOCVD grown InGaAs quantum dots (QD) active regions are also investigated, allowing for comparison to InGaAs QW material. The second part of my talk will cover intersubband-transition QW and quantum-box (QB) lasers. Quantum cascade (QC) lasers have emerged as compact and technologically important light sources in the mid-infrared (IR) and far-IR wavelength ranges infringing on the near-IR and terahertz spectral regions respectively. However, the overall power conversion efficiency, so-called wallplug efficiency, of the best QC lasers, emitting around 5 microns, is ˜9% in CW operation and very unlikely to exceed 15%. In order to dramatically improve the wallplug efficiency of mid-IR lasers (i.e., to about 50%), intersubband QB (IQB) lasers have been proposed. The basic idea, the optimal design and the progress towards the fabrication of IQB lasers will be presented.

A novel "gain chip" concept for high-power lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, Min; Li, Mingzhong; Wang, Zhenguo; Yan, Xiongwei; Jiang, Xinying; Zheng, Jiangang; Cui, Xudong; Zhang, Xiaomin

2017-05-01

High-power lasers, including high-peak power lasers (HPPL) and high-average power lasers (HAPL), attract much interest for enormous variety of applications in inertial fusion energy (IFE), materials processing, defense, spectroscopy, and high-field physics research. To meet the requirements of high efficiency and quality, a "gain chip" concept is proposed to properly design the pumping, cooling and lasing fields. The gain chip mainly consists of the laser diode arrays, lens duct, rectangle wave guide and slab-shaped gain media. For the pumping field, the pump light will be compressed and homogenized by the lens duct to high irradiance with total internal reflection, and further coupled into the gain media through its two edge faces. For the cooling field, the coolant travels along the flow channel created by the adjacent slabs in the other two edge-face direction, and cool the lateral faces of the gain media. For the lasing field, the laser beam travels through the lateral faces and experiences minimum thermal wavefront distortions. Thereby, these three fields are in orthogonality offering more spatial freedom to handle them during the construction of the lasers. Transverse gradient doping profiles for HPPL and HAPL have been employed to achieve uniform gain distributions (UGD) within the gain media, respectively. This UGD will improve the management for both amplified spontaneous emission (ASE) and thermal behavior. Since each "gain chip" has its own pump source, power scaling can be easily achieved by placing identical "gain chips" along the laser beam axis without disturbing the gain and thermal distributions. To detail our concept, a 1-kJ pulsed amplifier is designed and optical-to-optical efficiency up to 40% has been obtained. We believe that with proper coolant (gas or liquid) and gain media (Yb:YAG, Nd:glass or Nd:YAG) our "gain chip" concept might provide a general configuration for high-power lasers with high efficiency and quality.

Integrated monitoring of wind plant systems

NASA Astrophysics Data System (ADS)

Whelan, Matthew J.; Janoyan, Kerop D.; Qiu, Tong

2008-03-01

Wind power is a renewable source of energy that is quickly gaining acceptance by many. Advanced sensor technologies have currently focused solely on improving wind turbine rotor aerodynamics and increasing of the efficiency of the blade design and concentration. Alternatively, potential improvements in wind plant efficiency may be realized through reduction of reactionary losses of kinetic energy to the structural and substructural systems supporting the turbine mechanics. Investigation of the complete dynamic structural response of the wind plant is proposed using a large-scale, high-rate wireless sensor network. The wireless network enables sensors to be placed across the sizable structure, including the rotating blades, without consideration of cabling issues and the economic burden associated with large spools of measurement cables. A large array of multi-axis accelerometers is utilized to evaluate the modal properties of the system as well as individual members and would enable long-term structural condition monitoring of the wind turbine as well. Additionally, environmental parameters, including wind speed, temperature, and humidity, are wirelessly collected for correlation. Such a wireless system could be integrated with electrical monitoring sensors and actuators and incorporated into a remote multi-turbine centralized plant monitoring and control system.

Framing Innovation: Does an Instructional Vision Help Superintendents Gain Acceptance for a Large-Scale Technology Initiative?

ERIC Educational Resources Information Center

Flanagan, Gina E.

2014-01-01

There is limited research that outlines how a superintendent's instructional vision can help to gain acceptance of a large-scale technology initiative. This study explored how superintendents gain acceptance for a large-scale technology initiative (specifically a 1:1 device program) through various leadership actions. The role of the instructional…

High-efficiency ytterbium-free erbium-doped all-glass double cladding silicate glass fiber for resonantly-pumped fiber lasers.

PubMed

Qiang, Zexuan; Geng, Jihong; Luo, Tao; Zhang, Jun; Jiang, Shibin

2014-02-01

A highly efficient ytterbium-free erbium-doped silicate glass fiber has been developed for high-power fiber laser applications at an eye-safe wavelength near 1.55 μm. Our preliminary experiments show that high laser efficiency can be obtained from a relatively short length of the gain fiber when resonantly pumped at 1535 nm in both core- and cladding-pumping configurations. With a core-pumping configuration as high as 75%, optical-to-optical efficiency and 4 W output power were obtained at 1560 nm from a 1 m long gain fiber. When using a cladding-pumping configuration, approximately 13 W output power with 67.7% slope efficiency was demonstrated from a piece of 2 m long fiber. The lengths of silicate-based gain fiber are much shorter than their silica-based counterparts used in other experiments, which is significantly important for high-power narrow-band and/or pulsed laser applications.

Relative intensity noise transfer of large-bandwidth pump lasers in Raman fiber amplifiers

NASA Astrophysics Data System (ADS)

Keita, Kafing; Delaye, Philippe; Frey, Robert; Roosen, Gérald

2006-12-01

A theoretical analysis of the Raman amplification in optical fibers and the pump-to-signal relative intensity noise (RIN) transfer has been performed in the spectral domain. An efficient Raman amplification of a monochromatic signal beam by a large-bandwidth pump beam has been demonstrated for a pump bandwidth much smaller than the Raman linewidth. Under the same approximation the pump-to-signal RIN transfer has been calculated in both cases of copropagating and counterpropagating beams in the two limiting cases of modulated monochromatic and smooth-profile large-bandwidth pump beams. At low frequencies the excess of noise evidenced in the case of a modulated monochromatic pump beam did not exist in the case of large-bandwidth pseudoincoherent sources. As this noise reduction can be as large as 13 dB for a 40 dB net gain of the amplifier, such incoherent pumping sources must be considered for the purpose of low-noise Raman amplifiers.

Riccati parameterized self-similar waves in two-dimensional graded-index waveguide

NASA Astrophysics Data System (ADS)

Kumar De, Kanchan; Goyal, Amit; Raju, Thokala Soloman; Kumar, C. N.; Panigrahi, Prasanta K.

2015-04-01

An analytical method based on gauge-similarity transformation technique has been employed for mapping a (2+1)- dimensional variable coefficient coupled nonlinear Schrödinger equations (vc-CNLSE) with dispersion, nonlinearity and gain to standard NLSE. Under certain functional relations we construct a large family of self-similar waves in the form of bright similaritons, Akhmediev breathers and rogue waves. We report the effect of dispersion on the intensity of the solitary waves. Further, we illustrate the procedure to amplify the intensity of self-similar waves using isospectral Hamiltonian approach. This approach provides an efficient mechanism to generate analytically a wide class of tapering profiles and widths by exploiting the Riccati parameter. Equivalently, it enables one to control efficiently the self-similar wave structures and hence their evolution.

Effects of wind waves on horizontal array performance in shallow-water conditions

NASA Astrophysics Data System (ADS)

Zavol'skii, N. A.; Malekhanov, A. I.; Raevskii, M. A.; Smirnov, A. V.

2017-09-01

We analyze the influence of statistical effects of the propagation of an acoustic signal excited by a tone source in a shallow-water channel with a rough sea surface on the efficiency of a horizontal phased array. As the array characteristics, we consider the angular function of the array response for a given direction to the source and the coefficient of amplification of the signal-to-noise ratio (array gain). Numerical simulation was conducted in to the winter hydrological conditions of the Barents Sea in a wide range of parameters determining the spatial signal coherence. The results show the main physical effects of the influence of wind waves on the array characteristics and make it possible to quantitatively predict the efficiency of a large horizontal array in realistic shallow-water channels.

Post-weaning feed efficiency of tropically adapted purebred and crossbred calves when fed in either winter or spring

USDA-ARS?s Scientific Manuscript database

Earlier work has shown that young, tropically adapted (Brahman and Romosinuano) cattle do not gain as rapidly as temperately adapted (Angus) cattle during the winter in OK. The objective for this study was as to compare efficiency of gains between tropically- and temperately-adapted cattle breeds. O...

Genetic variance and covariance components for feed intake, average daily gain, and postweaning gain in growing beef cattle

USDA-ARS?s Scientific Manuscript database

Feed is the single most expensive cost related to a beef cattle production enterprise. Data collection to determine feed efficient animals is also costly. Currently a 70 d performance test is recommended for accurate calculation of efficiency. Previous research has suggested intake tests can be l...

Three-dimensional modeling of CPA to the multimillijoule level in tapered Yb-doped fibers for coherent combining systems.

PubMed

Andrianov, Alexey; Anashkina, Elena; Kim, Arkady; Meyerov, Iosif; Lebedev, Sergey; Sergeev, Alexander; Mourou, Gerard

2014-11-17

We developed a three-dimensional numerical model of Large-Mode-Area chirped pulse fiber amplifiers which includes nonlinear beam propagation in nonuniform multimode waveguides as well as gain spectrum dynamics in quasi-three-level active ions. We used our model in tapered Yb-doped fiber amplifiers and showed that single-mode propagation is maintained along the taper even in the presence of strong Kerr nonlinearity and saturated gain, allowing extraction of up to 3 mJ of output energy in 1 ns pulse. Energy scaling and its limitation as well as the influence of fiber taper bending and core irregularities on the amplifier performance were studied. We also investigated numerically the capabilities for compression and coherent combining of up to 36 perturbed amplifying channels and showed more than 70% combining efficiency, even with up to 11% of high-order modes in individual channels.

High Rise Building: The Mega Sculpture Made Of Steel, Concrete and Glass

NASA Astrophysics Data System (ADS)

Stefańska, Alicja; Załuski, Daniel

2017-10-01

High rise building has transformed from providing not only the expansion of floor space but functioning as mega sculpture in the city. The shift away from economic efficiency driven need is only expected to grow in the future. Based on literature studies; after analysing planning documents and case studies, it was examined whether the presumption that gaining the maximum amount of usable area is the only driving factor; or if the need for the creation of an image for the city provided a supplementary reason. The results showed that forming high rise buildings as three-dimensional sculptures is influenced not only by aesthetics, but also marketing. Visual distinction in the city skyline is economically beneficial for investors gaining not only functionality but art, enriching the cultural landscape. Organizing architectural competitions, public debates and following the latest art trends is therefore possible due to large budgets of such projects.

Gain degradation and efficiencies of spiral electron multipliers

NASA Technical Reports Server (NTRS)

Judge, R. J. R.; Palmer, D. A.

1973-01-01

The characteristics of spiral electron multipliers as functions of accumulated counts were investigated. The mean gain of the multipliers showed a steady decline from about 100 million when new, to about one million after 100 billion events when biased in a saturation mode. For prolonged use in a space environment, improved life expectancy might be obtained with a varying bias voltage adjusted to maintain the gain comfortably above a given discrimination level. Pulse-height distributions at various stages of the lifetime and variations of efficiency with energy of detected electrons are presented.

Laser amplifier chain

DOEpatents

Hackel, Richard P.

1992-01-01

A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.

QTLs associated with dry matter intake, metabolic mid-test weight, growth and feed efficiency have little overlap across 4 beef cattle studies.

PubMed

Saatchi, Mahdi; Beever, Jonathan E; Decker, Jared E; Faulkner, Dan B; Freetly, Harvey C; Hansen, Stephanie L; Yampara-Iquise, Helen; Johnson, Kristen A; Kachman, Stephen D; Kerley, Monty S; Kim, JaeWoo; Loy, Daniel D; Marques, Elisa; Neibergs, Holly L; Pollak, E John; Schnabel, Robert D; Seabury, Christopher M; Shike, Daniel W; Snelling, Warren M; Spangler, Matthew L; Weaber, Robert L; Garrick, Dorian J; Taylor, Jeremy F

2014-11-20

The identification of genetic markers associated with complex traits that are expensive to record such as feed intake or feed efficiency would allow these traits to be included in selection programs. To identify large-effect QTL, we performed a series of genome-wide association studies and functional analyses using 50 K and 770 K SNP genotypes scored in 5,133 animals from 4 independent beef cattle populations (Cycle VII, Angus, Hereford and Simmental×Angus) with phenotypes for average daily gain, dry matter intake, metabolic mid-test body weight and residual feed intake. A total of 5, 6, 11 and 10 significant QTL (defined as 1-Mb genome windows with Bonferroni-corrected P-value<0.05) were identified for average daily gain, dry matter intake, metabolic mid-test body weight and residual feed intake, respectively. The identified QTL were population-specific and had little overlap across the 4 populations. The pleiotropic or closely linked QTL on BTA 7 at 23 Mb identified in the Angus population harbours a promising candidate gene ACSL6 (acyl-CoA synthetase long-chain family member 6), and was the largest effect QTL associated with dry matter intake and mid-test body weight explaining 10.39% and 14.25% of the additive genetic variance, respectively. Pleiotropic or closely linked QTL associated with average daily gain and mid-test body weight were detected on BTA 6 at 38 Mb and BTA 7 at 93 Mb confirming previous reports. No QTL for residual feed intake explained more than 2.5% of the additive genetic variance in any population. Marker-based estimates of heritability ranged from 0.21 to 0.49 for residual feed intake across the 4 populations. This GWAS study, which is the largest performed for feed efficiency and its component traits in beef cattle to date, identified several large-effect QTL that cumulatively explained a significant percentage of additive genetic variance within each population. Differences in the QTL identified among the different populations may be due to differences in power to detect QTL, environmental variation, or differences in the genetic architecture of trait variation among breeds. These results enhance our understanding of the biology of growth, feed intake and utilisation in beef cattle.

Biodiversity gains from efficient use of private sponsorship for flagship species conservation.

PubMed

Bennett, Joseph R; Maloney, Richard; Possingham, Hugh P

2015-04-22

To address the global extinction crisis, both efficient use of existing conservation funding and new sources of funding are vital. Private sponsorship of charismatic 'flagship' species conservation represents an important source of new funding, but has been criticized as being inefficient. However, the ancillary benefits of privately sponsored flagship species conservation via actions benefiting other species have not been quantified, nor have the benefits of incorporating such sponsorship into objective prioritization protocols. Here, we use a comprehensive dataset of conservation actions for the 700 most threatened species in New Zealand to examine the potential biodiversity gains from national private flagship species sponsorship programmes. We find that private funding for flagship species can clearly result in additional species and phylogenetic diversity conserved, via conservation actions shared with other species. When private flagship species funding is incorporated into a prioritization protocol to preferentially sponsor shared actions, expected gains can be more than doubled. However, these gains are consistently smaller than expected gains in a hypothetical scenario where private funding could be optimally allocated among all threatened species. We recommend integrating private sponsorship of flagship species into objective prioritization protocols to sponsor efficient actions that maximize biodiversity gains, or wherever possible, encouraging private donations for broader biodiversity goals. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Biodiversity gains from efficient use of private sponsorship for flagship species conservation

PubMed Central

Bennett, Joseph R.; Maloney, Richard; Possingham, Hugh P.

2015-01-01

To address the global extinction crisis, both efficient use of existing conservation funding and new sources of funding are vital. Private sponsorship of charismatic ‘flagship’ species conservation represents an important source of new funding, but has been criticized as being inefficient. However, the ancillary benefits of privately sponsored flagship species conservation via actions benefiting other species have not been quantified, nor have the benefits of incorporating such sponsorship into objective prioritization protocols. Here, we use a comprehensive dataset of conservation actions for the 700 most threatened species in New Zealand to examine the potential biodiversity gains from national private flagship species sponsorship programmes. We find that private funding for flagship species can clearly result in additional species and phylogenetic diversity conserved, via conservation actions shared with other species. When private flagship species funding is incorporated into a prioritization protocol to preferentially sponsor shared actions, expected gains can be more than doubled. However, these gains are consistently smaller than expected gains in a hypothetical scenario where private funding could be optimally allocated among all threatened species. We recommend integrating private sponsorship of flagship species into objective prioritization protocols to sponsor efficient actions that maximize biodiversity gains, or wherever possible, encouraging private donations for broader biodiversity goals. PMID:25808885

Equity of tolling : myths and realities

DOT National Transportation Integrated Search

2010-02-26

This presentation discusses the equity and efficiency of tolling and the increases in efficiency from efficiency gains. Efficiency and equity are inextricably related, and they are not inherently in conflict. Congestion pricing generates positive net...

Stacking with stochastic cooling

NASA Astrophysics Data System (ADS)

Caspers, Fritz; Möhl, Dieter

2004-10-01

Accumulation of large stacks of antiprotons or ions with the aid of stochastic cooling is more delicate than cooling a constant intensity beam. Basically the difficulty stems from the fact that the optimized gain and the cooling rate are inversely proportional to the number of particles 'seen' by the cooling system. Therefore, to maintain fast stacking, the newly injected batch has to be strongly 'protected' from the Schottky noise of the stack. Vice versa the stack has to be efficiently 'shielded' against the high gain cooling system for the injected beam. In the antiproton accumulators with stacking ratios up to 105 the problem is solved by radial separation of the injection and the stack orbits in a region of large dispersion. An array of several tapered cooling systems with a matched gain profile provides a continuous particle flux towards the high-density stack core. Shielding of the different systems from each other is obtained both through the spatial separation and via the revolution frequencies (filters). In the 'old AA', where the antiproton collection and stacking was done in one single ring, the injected beam was further shielded during cooling by means of a movable shutter. The complexity of these systems is very high. For more modest stacking ratios, one might use azimuthal rather than radial separation of stack and injected beam. Schematically half of the circumference would be used to accept and cool new beam and the remainder to house the stack. Fast gating is then required between the high gain cooling of the injected beam and the low gain stack cooling. RF-gymnastics are used to merge the pre-cooled batch with the stack, to re-create free space for the next injection, and to capture the new batch. This scheme is less demanding for the storage ring lattice, but at the expense of some reduction in stacking rate. The talk reviews the 'radial' separation schemes and also gives some considerations to the 'azimuthal' schemes.

Economic innovation and efficiency gains as the driving force for accelerating carbon dioxide emissions

NASA Astrophysics Data System (ADS)

Garrett, T. J.

2012-12-01

It is normally assumed that gains in energy efficiency are one of the best routes that society has available to it for stabilizing future carbon dioxide emissions. For a given degree of economic productivity less energy is consumed and a smaller quantity of fossil fuels is required. While certainly this observation is true in the instant, it ignores feedbacks in the economic system such that efficiency gains ultimately lead to greater energy consumption: taken as a global whole, they permit civilization to accelerate its expansion into the energy reserves that sustain it. Here this argument is formalized from a general thermodynamic perspective. The core result is that there exists a fixed, time-independent link between a very general representation of global inflation-adjusted economic wealth (units currency) and civilization's total capacity to consume power (units energy per time). Based on 40 years of available statistics covering more than a tripling of global GDP and a doubling of wealth, this constant has a value of 7.1 +/- 0.01 Watts per one thousand 2005 US dollars. Essentially, wealth is power. Civilization grows by dissipating power in order to sustain all its current activities and to incorporate more raw material into its existing structure. Growth of its structure is related to economic production, so more energy efficient economic production facilitates growth. Growth is into the reserves that sustain civilization, in which case there is a positive feedback in the economic system whereby energy efficiency gains ultimately "backfire" if their intended purpose is to reduce energy consumption and carbon dioxide emissions. The analogy that can be made is to a growing child: a healthy child who efficiently incorporates food into her structure grows quickly and is able to consume more in following years. Economically, an argument is made that, for a range of reasons, there are good reasons to refer to efficiency gains as economic "innovation", both for their physical nature and their links to traditional neo-classical economics.

Investigation to develop a multistage forest sampling inventory system using ERTS-1 imagery

NASA Technical Reports Server (NTRS)

Langley, P. G.; Vanroessel, J. W. (Principal Investigator); Wert, S. L.

1975-01-01

The author has identified the following significant results. The annotation system produced a RMSE of about 200 m ground distance in the MSS data system with the control data used. All the analytical MSS interpretation models tried were highly significant. However, the gains in forest sampling efficiency that can be achieved by using the models vary from zero to over 50 percent depending on the area to which they are applied and the sampling method used. Among the sampling methods tried, regression sampling yielded substantial and the most consistent gains. The single most significant variable in the interpretation model was the difference between bands 5 and 7. The contrast variable, computed by the Hadamard transform was significant but did not contribute much to the interpretation model. Forest areas containing very large timber volumes because of large tree sizes were not separable from areas of similar crown cover but containing smaller trees using ERTS image interpretation only. All correlations between space derived timber volume predictions and estimates obtained from aerial and ground sampling were relatively low but significant and stable. There was a much stronger relationship between variables derived from MSS and U2 data than between U2 and ground data.

Optimum allocation of test resources and comparison of breeding strategies for hybrid wheat.

PubMed

Longin, C Friedrich H; Mi, Xuefei; Melchinger, Albrecht E; Reif, Jochen C; Würschum, Tobias

2014-10-01

The use of a breeding strategy combining the evaluation of line per se with testcross performance maximizes annual selection gain for hybrid wheat breeding. Recent experimental studies confirmed a high commercial potential for hybrid wheat requiring the design of optimum breeding strategies. Our objectives were to (1) determine the optimum allocation of the type and number of testers, the number of test locations and the number of doubled haploid lines for different breeding strategies, (2) identify the best breeding strategy and (3) elaborate key parameters for an efficient hybrid wheat breeding program. We performed model calculations using the selection gain for grain yield as target variable to optimize the number of lines, testers and test locations in four different breeding strategies. A breeding strategy (BS2) combining the evaluation of line per se performance and general combining ability (GCA) had a far larger annual selection gain across all considered scenarios than a breeding strategy (BS1) focusing only on GCA. In the combined strategy, the production of testcross seed conducted in parallel with the first yield trial for line per se performance (BS2rapid) resulted in a further increase of the annual selection gain. For the current situation in hybrid wheat, this relative superiority of the strategy BS2rapid amounted to 67 % in annual selection gain compared to BS1. Varying a large number of parameters, we identified the high costs for hybrid seed production and the low variance of GCA in hybrid wheat breeding as key parameters limiting selection gain in BS2rapid.

Sub-Selective Quantization for Learning Binary Codes in Large-Scale Image Search.

PubMed

Li, Yeqing; Liu, Wei; Huang, Junzhou

2018-06-01

Recently with the explosive growth of visual content on the Internet, large-scale image search has attracted intensive attention. It has been shown that mapping high-dimensional image descriptors to compact binary codes can lead to considerable efficiency gains in both storage and performing similarity computation of images. However, most existing methods still suffer from expensive training devoted to large-scale binary code learning. To address this issue, we propose a sub-selection based matrix manipulation algorithm, which can significantly reduce the computational cost of code learning. As case studies, we apply the sub-selection algorithm to several popular quantization techniques including cases using linear and nonlinear mappings. Crucially, we can justify the resulting sub-selective quantization by proving its theoretic properties. Extensive experiments are carried out on three image benchmarks with up to one million samples, corroborating the efficacy of the sub-selective quantization method in terms of image retrieval.

A semiparametric graphical modelling approach for large-scale equity selection

PubMed Central

Liu, Han; Mulvey, John; Zhao, Tianqi

2016-01-01

We propose a new stock selection strategy that exploits rebalancing returns and improves portfolio performance. To effectively harvest rebalancing gains, we apply ideas from elliptical-copula graphical modelling and stability inference to select stocks that are as independent as possible. The proposed elliptical-copula graphical model has a latent Gaussian representation; its structure can be effectively inferred using the regularized rank-based estimators. The resulting algorithm is computationally efficient and scales to large data-sets. To show the efficacy of the proposed method, we apply it to conduct equity selection based on a 16-year health care stock data-set and a large 34-year stock data-set. Empirical tests show that the proposed method is superior to alternative strategies including a principal component analysis-based approach and the classical Markowitz strategy based on the traditional buy-and-hold assumption. PMID:28316507

On the feasibility of a fiber-based inertial fusion laser driver

NASA Astrophysics Data System (ADS)

Labaune, C.; Hulin, D.; Galvanauskas, A.; Mourou, G. A.

2008-08-01

One critical issue for the realization of Inertial Fusion Energy (IFE) power plants is the driver efficiency. High driver efficiency will greatly relax the driver energy requested to produce a fusion gain, resulting in more compact and less costly facilities. Among lasers, systems based on guided wave such as diode pumped Yb:glass fiber-amplifiers with a demonstrated overall efficiency close to 70% as opposed to few percents for systems based on free propagation, offer some intriguing opportunities. Guided optics provides the enormous advantage to directly benefit from the telecommunication industry where components are made cheap, rugged, well tested, environmentally stable, with lifetimes measured in tens of years and compatible with massive manufacturing. In this paper, we are studying the possibility to design a laser driver solely based on guided wave optics. We call this concept FAN for Fiber Amplification Network. It represents a profound departure from already proposed laser drivers all based on free propagation optics. The system will use a large number of identical fibers to combines long (ns) and short (ps) pulses that are needed for the fast ignition scheme. Technical details are discussed relative to fiber type, pump, phasing, pulse shaping and timing as well as fiber distribution around the chamber. The proposed fiber driver provides maximum and independent control on the wavefront, pulse duration, pulse shape, timing, making possible reaching the highest gain. The massive manufacturing will be amenable to a cheaper facility with an easy upkeep.

Intensification of oily waste waters purification by means of liquid atomization

NASA Astrophysics Data System (ADS)

Eskin, A. A.; Tkach, N. S.; Kim, M. I.; Zakharov, G. A.

2017-10-01

In this research, a possibility of using liquid atomization for improving the efficiency of purification of wastewater by different methods has been studied. By the introduced method and an experimental setup for wastewater purification, saturation rate increases with its purification by means of dissolved air flotation. Liquid atomization under excess pressure allows to gain a large interfacial area between the saturated liquid and air, which may increase the rate of purified liquid saturation almost twice, compared to the existing methods of saturation. Current disadvantages of liquid atomization used for intensification of wastewater purification include high energy cost and secondary emulsion of polluting agents. It is also known that by means of liquid atomization a process of ozonizing can be intensified. Large contact surface between the purified liquid and ozone-air mixture increases the oxidizing efficiency, which allows to diminish ozone discharge. Liquid atomization may be used for purification of wastewaters by ultraviolet radiation. Small drops of liquid will be proportionally treated by ultraviolet, which makes it possible to do purification even of turbid wastewaters. High-speed liquid motion will prevent the pollution of quartz tubes of ultraviolet lamps.

Zero-reabsorption doped-nanocrystal luminescent solar concentrators.

PubMed

Erickson, Christian S; Bradshaw, Liam R; McDowall, Stephen; Gilbertson, John D; Gamelin, Daniel R; Patrick, David L

2014-04-22

Optical concentration can lower the cost of solar energy conversion by reducing photovoltaic cell area and increasing photovoltaic efficiency. Luminescent solar concentrators offer an attractive approach to combined spectral and spatial concentration of both specular and diffuse light without tracking, but they have been plagued by luminophore self-absorption losses when employed on practical size scales. Here, we introduce doped semiconductor nanocrystals as a new class of phosphors for use in luminescent solar concentrators. In proof-of-concept experiments, visibly transparent, ultraviolet-selective luminescent solar concentrators have been prepared using colloidal Mn(2+)-doped ZnSe nanocrystals that show no luminescence reabsorption. Optical quantum efficiencies of 37% are measured, yielding a maximum projected energy concentration of ∼6× and flux gain for a-Si photovoltaics of 15.6 in the large-area limit, for the first time bounded not by luminophore self-absorption but by the transparency of the waveguide itself. Future directions in the use of colloidal doped nanocrystals as robust, processable spectrum-shifting phosphors for luminescent solar concentration on the large scales required for practical application of this technology are discussed.

Lasing efficiency of Er-Yb-Cr-glass: A temperature study (Conference Presentation)

NASA Astrophysics Data System (ADS)

George, Simi A.; Hayden, Joseph S.; Davis, Mark J.

2017-03-01

Retina-safe operation in open-air is of high interest to the next generation of lasers that are being utilized for many industrial, defense and medical applications. Those wavelengths that are considered to be the best for retina safe operations (also called eye-safe) fall in the range between 1400nm and1800nm. This wavelength region also coincides with the low loss window of fused silica fibers used for optical fiber communications [1], where the S and C bands near 1500nm are heavily utilized for long range communications due to the lowest attenuation losses possible in the fiber. The trivalent Er ion can produce direct emission into the 1540 nm wavelength, thus, it is the rare-earth emitter of choice for many eye-safe applications. In recent years, the need for high beam quality under passive operation in open air applications have renewed interest in Er-doped bulk glasses as the gain material of choice for solid-state eye-safe lasers. The need for performance stability under a broad operating range from -400C to 1000C without active cooling is a challenge for amorphous gain materials. Moreover, there is very little known about how temperature may affect performance. In this study, we describe our first attempts to understand material behavior by systematically analyzing temperature driven variations exhibited in absorption and emission from the commercially available gain materials. As part of these investigations, we will also present our method for assessing quantum efficiency through measurements for critical evaluation from laser community at large.

Optimized Ion Energy Profiles for Heavy Ion Direct Drive Targets

NASA Astrophysics Data System (ADS)

Hay, Michael J.; Barnard, John J.; Perkins, L. John; Logan, B. Grant

2009-11-01

Recent 1-D implosion calculations [1] have characterized pure-DT targets delivering gains of 50-90 with less than 0.5 MJ of heavy ion direct drive. With a payload fraction of 1/3, these low-aspect ratio targets operate near the peak of rocket efficiency and achieve ˜10% overall coupling efficiencies (vs. the 15-20% efficiencies analytically predicted for less stable, higher-aspect ratio targets). In Ref. 1, the ion energy is ramped directly from a 50 MeV foot pulse to a 500 MeV main pulse. In this paper, we instead tune the ion energy throughout the drive to closely match the beam deposition with the inward progress of the ablation front. We will present the ion energy and intensity time histories that maximize drive efficiency and gain for a single target at constant integrated drive energy. [1] L. J. Perkins, B. G. Logan, J. J. Barnard, and M. J. Hay. ``High Efficiency High Gain Heavy Ion Direct Drive Targets,'' Bulletin of the American Physical Society, vol. 54: DPP, Nov. 2009.

Broadband gain in poly(3-hexylthiophene):phenyl-C{sub 61}-butyric-acid-methyl-ester photodetectors enabled by a semicontinuous gold interlayer

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

Melancon, Justin M.; Živanović, Sandra R., E-mail: sz@latech.edu

2014-10-20

Substantial broadband photoconductive gain has been realized for organic, thin-film photodetectors with a poly(3-hexylthiophene):phenyl-C{sub 61}-butyric-acid-methyl-ester (P3HT:PCBM) active layer at low bias voltages. External quantum efficiencies upwards of 1500% were achieved when a semicontinuous gold layer was introduced at the anode interface. Significant gain was also observed in the sub-band gap, near infrared region where the external quantum efficiency approached 100% despite the lack of a sensitizer. The gain response was highly dependent on the thickness of the active layer of the photodetector with the best results achieved with the thinnest devices. The gain is the result of the injection ofmore » secondary electrons due to hole charge trapping at the semicontinuous gold layer.« less

A Preliminary Model for Spacecraft Propulsion Performance Analysis Based on Nuclear Gain and Subsystem Mass-Power Balances

NASA Technical Reports Server (NTRS)

Chakrabarti, Suman; Schmidt, George R.; Thio, Y. C.; Hurst, Chantelle M.

1999-01-01

A preliminary model for spacecraft propulsion performance analysis based on nuclear gain and subsystem mass-power balances are presented in viewgraph form. For very fast missions with straight-line trajectories, it has been shown that mission trip time is proportional to the cube root of alpha. Analysis of spacecraft power systems via a power balance and examination of gain vs. mass-power ratio has shown: 1) A minimum gain is needed to have enough power for thruster and driver operation; and 2) Increases in gain result in decreases in overall mass-power ratio, which in turn leads to greater achievable accelerations. However, subsystem mass-power ratios and efficiencies are crucial: less efficient values for these can partially offset the effect of nuclear gain. Therefore, it is of interest to monitor the progress of gain-limited subsystem technologies and it is also possible that power-limited systems with sufficiently low alpha may be competitive for such ambitious missions. Topics include Space flight requirements; Spacecraft energy gain; Control theory for performance; Mission assumptions; Round trips: Time and distance; Trip times; Vehicle acceleration; and Minimizing trip times.

Superior broadband antireflection from buried Mie resonator arrays for high-efficiency photovoltaics

PubMed Central

Zhong, Sihua; Zeng, Yang; Huang, Zengguang; Shen, Wenzhong

2015-01-01

Establishing reliable and efficient antireflection structures is of crucial importance for realizing high-performance optoelectronic devices such as solar cells. In this study, we provide a design guideline for buried Mie resonator arrays, which is composed of silicon nanostructures atop a silicon substrate and buried by a dielectric film, to attain a superior antireflection effect over a broadband spectral range by gaining entirely new discoveries of their antireflection behaviors. We find that the buried Mie resonator arrays mainly play a role as a transparent antireflection structure and their antireflection effect is insensitive to the nanostructure height when higher than 150 nm, which are of prominent significance for photovoltaic applications in the reduction of photoexcited carrier recombination. We further optimally combine the buried Mie resonator arrays with micron-scale textures to maximize the utilization of photons, and thus have successfully achieved an independently certified efficiency of 18.47% for the nanostructured silicon solar cells on a large-size wafer (156 mm × 156 mm). PMID:25746848

Progress Towards Highly Efficient Windows for Zero—Energy Buildings

NASA Astrophysics Data System (ADS)

Selkowitz, Stephen

2008-09-01

Energy efficient windows could save 4 quads/year, with an additional 1 quad/year gain from daylighting in commercial buildings. This corresponds to 13% of energy used by US buildings and 5% of all energy used by the US. The technical potential is thus very large and the economic potential is slowly becoming a reality. This paper describes the progress in energy efficient windows that employ low-emissivity glazing, electrochromic switchable coatings and other novel materials. Dynamic systems are being developed that use sensors and controls to modulate daylighting and shading contributions in response to occupancy, comfort and energy needs. Improving the energy performance of windows involves physics in a variety of application: optics, heat transfer, materials science and applied engineering. Technical solutions must also be compatible with national policy, codes and standards, economics, business practice and investment, real and perceived risks, comfort, health, safety, productivity, amenities, and occupant preference and values. The challenge is to optimize energy performance by understanding and reinforcing the synergetic coupling between these many issues.

Finding Regions of Interest on Toroidal Meshes

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

Wu, Kesheng; Sinha, Rishi R; Jones, Chad

2011-02-09

Fusion promises to provide clean and safe energy, and a considerable amount of research effort is underway to turn this aspiration intoreality. This work focuses on a building block for analyzing data produced from the simulation of microturbulence in magnetic confinementfusion devices: the task of efficiently extracting regions of interest. Like many other simulations where a large amount of data are produced,the careful study of ``interesting'' parts of the data is critical to gain understanding. In this paper, we present an efficient approach forfinding these regions of interest. Our approach takes full advantage of the underlying mesh structure in magneticmore » coordinates to produce acompact representation of the mesh points inside the regions and an efficient connected component labeling algorithm for constructingregions from points. This approach scales linearly with the surface area of the regions of interest instead of the volume as shown with bothcomputational complexity analysis and experimental measurements. Furthermore, this new approach is 100s of times faster than a recentlypublished method based on Cartesian coordinates.« less

Efficient prediction of terahertz quantum cascade laser dynamics from steady-state simulations

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

Agnew, G.; Lim, Y. L.; Nikolić, M.

2015-04-20

Terahertz-frequency quantum cascade lasers (THz QCLs) based on bound-to-continuum active regions are difficult to model owing to their large number of quantum states. We present a computationally efficient reduced rate equation (RE) model that reproduces the experimentally observed variation of THz power with respect to drive current and heat-sink temperature. We also present dynamic (time-domain) simulations under a range of drive currents and predict an increase in modulation bandwidth as the current approaches the peak of the light–current curve, as observed experimentally in mid-infrared QCLs. We account for temperature and bias dependence of the carrier lifetimes, gain, and injection efficiency,more » calculated from a full rate equation model. The temperature dependence of the simulated threshold current, emitted power, and cut-off current are thus all reproduced accurately with only one fitting parameter, the interface roughness, in the full REs. We propose that the model could therefore be used for rapid dynamical simulation of QCL designs.« less

Efficiency enhancement of slow-wave electron-cyclotron maser by a second-order shaping of the magnetic field in the low-gain limit

NASA Astrophysics Data System (ADS)

Liu, Si-Jia; Zhang, Yu-Fei; Wang, Kang; Li, Yong-Ming; Jing, Jian

2017-03-01

Based on the anomalous Doppler effect, we put forward a proposal to enhance the conversion efficiency of the slow-wave electron cyclotron masers (ECM) under the resonance condition. Compared with previous studies, we add a second-order shaping term in the guild magnetic field. Theoretical analyses and numerical calculations show that it can enhance the conversion efficiency in the low-gain limit. The case of the initial velocity spread of electrons satisfying the Gaussian distribution is also analysed numerically.

Efficiency enhancement of slow-wave electron-cyclotron maser by a second-order shaping of the magnetic field in the low-gain limit

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

Liu, Si-Jia; Zhang, Yu-Fei; Wang, Kang

Based on the anomalous Doppler effect, we put forward a proposal to enhance the conversion efficiency of the slow-wave electron cyclotron masers (ECM) under the resonance condition. Compared with previous studies, we add a second-order shaping term in the guild magnetic field. Theoretical analyses and numerical calculations show that it can enhance the conversion efficiency in the low-gain limit. The case of the initial velocity spread of electrons satisfying the Gaussian distribution is also analysed numerically.

Laser amplifier chain

DOEpatents

Hackel, R.P.

1992-10-20

A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain. 6 figs.

Face pumping of thin, solid-state slab lasers with laser diodes.

PubMed

Faulstich, A; Baker, H J; Hall, D R

1996-04-15

A new technique for face pumping of slab lasers uses transfer of light from 10 quasi-cw laser diode bars through a slotted mirror into a rectangular, highly ref lective pump chamber, giving efficient multipass pumping of a thin Nd:glass slab laser. A slope efficiency of 28% and a maximum pulse energy of 65 mJ have been obtained, and gain and loss measurements with thickness t = 0.45-1.04 mm have confirmed the 1/t scaling of gain in thin slabs and the high efficiency of pump light transfer.

On the problem of constructing a modern, economic radiotelescope complex

NASA Technical Reports Server (NTRS)

Bogomolov, A. F.; Sokolov, A. G.; Poperechenko, B. A.; Polyak, V. S.

1977-01-01

Criteria for comparing and planning the technical and economic characteristics of large parabolic reflector antenna systems and other types used in radioastronomy and deep space communications are discussed. The experience gained in making and optimizing a series of highly efficient parabolic antennas in the USSR is reviewed. Several ways are indicated for further improving the complex characteristics of antennas similar to the original TNA-1500 64m radio telescope. The suggestions can be applied in planning the characteristics of radiotelescopes which are now being built, in particular, the TNA-8000 with a diameter of 128 m.

Image processing for optical mapping.

PubMed

Ravindran, Prabu; Gupta, Aditya

2015-01-01

Optical Mapping is an established single-molecule, whole-genome analysis system, which has been used to gain a comprehensive understanding of genomic structure and to study structural variation of complex genomes. A critical component of Optical Mapping system is the image processing module, which extracts single molecule restriction maps from image datasets of immobilized, restriction digested and fluorescently stained large DNA molecules. In this review, we describe robust and efficient image processing techniques to process these massive datasets and extract accurate restriction maps in the presence of noise, ambiguity and confounding artifacts. We also highlight a few applications of the Optical Mapping system.

Multiplicative Forests for Continuous-Time Processes

PubMed Central

Weiss, Jeremy C.; Natarajan, Sriraam; Page, David

2013-01-01

Learning temporal dependencies between variables over continuous time is an important and challenging task. Continuous-time Bayesian networks effectively model such processes but are limited by the number of conditional intensity matrices, which grows exponentially in the number of parents per variable. We develop a partition-based representation using regression trees and forests whose parameter spaces grow linearly in the number of node splits. Using a multiplicative assumption we show how to update the forest likelihood in closed form, producing efficient model updates. Our results show multiplicative forests can be learned from few temporal trajectories with large gains in performance and scalability. PMID:25284967

Multiplicative Forests for Continuous-Time Processes.

PubMed

Weiss, Jeremy C; Natarajan, Sriraam; Page, David

2012-01-01

Learning temporal dependencies between variables over continuous time is an important and challenging task. Continuous-time Bayesian networks effectively model such processes but are limited by the number of conditional intensity matrices, which grows exponentially in the number of parents per variable. We develop a partition-based representation using regression trees and forests whose parameter spaces grow linearly in the number of node splits. Using a multiplicative assumption we show how to update the forest likelihood in closed form, producing efficient model updates. Our results show multiplicative forests can be learned from few temporal trajectories with large gains in performance and scalability.

Eco-efficiency improvements in industrial water-service systems: assessing options with stakeholders.

PubMed

Levidow, Les; Lindgaard-Jørgensen, Palle; Nilsson, Asa; Skenhall, Sara Alongi; Assimacopoulos, Dionysis

2014-01-01

The well-known eco-efficiency concept helps to assess the economic value and resource burdens of potential improvements by comparison with the baseline situation. But eco-efficiency assessments have generally focused on a specific site, while neglecting wider effects, for example, through interactions between water users and wastewater treatment (WWT) providers. To address the methodological gap, the EcoWater project has developed a method and online tools for meso-level analysis of the entire water-service value chain. This study investigated improvement options in two large manufacturing companies which have significant potential for eco-efficiency gains. They have been considering investment in extra processes which can lower resource burdens from inputs and wastewater, as well as internalising WWT processes. In developing its methodology, the EcoWater project obtained the necessary information from many agents, involved them in the meso-level assessment and facilitated their discussion on alternative options. Prior discussions with stakeholders stimulated their attendance at a workshop to discuss a comparative eco-efficiency assessment for whole-system improvement. Stakeholders expressed interest in jointly extending the EcoWater method to more options and in discussing investment strategies. In such ways, optimal solutions will depend on stakeholders overcoming fragmentation by sharing responsibility and knowledge.

Measuring environmental efficiency of agricultural water use: a Luenberger environmental indicator.

PubMed

Azad, Md A S; Ancev, Tihomir

2014-12-01

Irrigated agriculture creates substantial environmental pressures by withdrawing large quantities of water, leaving rivers and wetlands empty and unable to support the valuable ecosystems that depend on the water resource. The key challenge facing society is that of balancing water extractions for agricultural production and other uses with provision of appropriate environmental flow to maintain healthy rivers and wetlands. Measuring tradeoffs between economic gain of water use in agriculture and its environmental pressures can contribute to constructing policy instruments for improved water resource management. The aim of this paper is to develop a modelling framework to measure these tradeoffs. Using a new approach - Luenberger environmental indicator - the study derives environmental efficiency scores for various types of irrigation enterprises across seventeen natural resource management regions within the Murray-Darling Basin, Australia. Findings show that there is a substantial variation in environmental performance of irrigation enterprises across the regions. Some enterprises were found to be relatively environmentally efficient in some regions, but they were not efficient in others. The environmental efficiency scores could be used as a guideline for formulating regional policy and strategy to achieve sustainable water use in the agricultural sector. Copyright © 2014 Elsevier Ltd. All rights reserved.

Feed efficiency of tropically adapted cattle when fed in winter or spring in a temperate location.

PubMed

Coleman, S W; Chase, C C; Phillips, W A; Riley, D G

2018-04-16

Earlier work has shown that young, tropically adapted cattle do not gain as rapidly as temperately adapted cattle during the winter in Oklahoma. The objective for this study was to determine if efficiency of gains was also impacted in tropically adapted cattle and if efficiency was consistent over different seasons. Over 3 yrs, 240 straightbred and crossbred steers (F1 and three-way crosses) of Angus, Brahman or Romosinuano breeding, born in Brooksville, FL were transported to El Reno, OK in October and fed in two phases to determine performance, individual intake and efficiency. Phase 1 (WIN) began in November after a 28 d recovery from shipping stress and Phase 2 (SS) began in March, 28 d following completion of WIN each year. The diet for WIN was a grower diet (14% CP, 1.10 Mcal NEg/kg) and that for the SS was a feedlot diet (12.8% CP; 1.33 Mcal NEg/kg). After a 14 d adjustment to diet and facilities, intake trials were conducted over a period of 56 to 162 d for determination of intake and gain for efficiency. Body weights were recorded at approximately 14 d intervals, and initial BW, median BW, and ADG were determined from individual animal regressions of BW on days on feed (DOF). Individual daily DMI was then regressed by phase on median BW and ADG, and residuals of regression were recorded as residual feed intake (RFI). Similarly, daily gain was regressed by phase on median BW and DMI, and errors of regression were recorded as residual gain (RADG). Gain to feed (G:F) was also calculated. The statistical model to evaluate ADG, DMI, and efficiency included fixed effects of dam age (3 to 4, 5, 6 to10, and > 10yr), harvest group (3 per year), age on test, and a nested term DT(ST x XB) where DT = proportion tropical breeding of dam (0, 0.5, or 1), ST= proportion tropical breeding of sire (1, or 0), and XB whether the calf was straightbred or crossbred. Year of record, sire(ST x XB) and pen were random effects. Pre-weaning ADG and BW increased (P < 0.05) with level of genetic tropical influence, but during the WIN, ADG and efficiency estimated by G:F and RADG declined (P < 0.05). Tropical influence had little effect on RFI during the WIN, or on most traits during SS. In general during SS, crossbred steers gained faster, and were more efficient by G:F and RADG (P < 0.05) than straightbred steers. Simple correlations, both Pearson and Spearman, between RFI in WIN and RFI in SS were 0.51 (P < 0.001) whereas that for RADG was 0.17 (P < 0.01).

Novel sensors to enable closed-loop active clearance control in gas turbine engines

NASA Astrophysics Data System (ADS)

Geisheimer, Jonathan; Holst, Tom

2014-06-01

Active clearance control within the turbine section of gas turbine engines presents and opportunity within aerospace and industrial applications to improve operating efficiencies and the life of downstream components. Open loop clearance control is currently employed during the development of all new large core aerospace engines; however, the ability to measure the gap between the blades and the case and close down the clearance further presents as opportunity to gain even greater efficiencies. The turbine area is one of the harshest environments for long term placement of a sensor in addition to the extreme accuracy requirements required to enable closed loop clearance control. This paper gives an overview of the challenges of clearance measurements within the turbine as well as discusses the latest developments of a microwave sensor designed for this application.

Comparison of efficiency and feedback characteristics of techniques of coupling semiconductor lasers into single-mode fiber.

PubMed

Wenke, G; Zhu, Y

1983-12-01

The coupling of CSP lasers to single-mode fibers with different coupling structures made on the fiber face is investigated. In this case easy to make coupling arrangements such as tapers and microlenses, result in a high launching efficiency (approximately 2-dB loss), in contrast to launching from gain-guided lasers with strong astigmatism and a broader far-field pattern. Index-guiding lasers exhibit, however, a higher sensitivity to optical feedback. Laser output power and wavelength are changed due to reflections from the fiber tip. Critical distances exist which lead to a highly unstable laser spectrum. A comparison of the influence of various fiber faces on laser power and wavelength stability is presented. It is concluded that a tapered fiber end with a large working distance reduces the influence on the laser's performance.

Fuselage Boundary Layer Ingestion Propulsion Applied to a Thin Haul Commuter Aircraft for Optimal Efficiency

NASA Technical Reports Server (NTRS)

Mikic, Gregor Veble; Stoll, Alex; Bevirt, JoeBen; Grah, Rok; Moore, Mark D.

2016-01-01

Theoretical and numerical aspects of aerodynamic efficiency of propulsion systems are studied. Focus is on types of propulsion that closely couples to the aerodynamics of the complete vehicle. We discuss the effects of local flow fields, which are affected both by conservative flow acceleration as well as total pressure losses, on the efficiency of boundary layer immersed propulsion devices. We introduce the concept of a boundary layer retardation turbine that helps reduce skin friction over the fuselage. We numerically investigate efficiency gains offered by boundary layer and wake interacting devices. We discuss the results in terms of a total energy consumption framework and show that efficiency gains offered depend on all the elements of the propulsion system.

Infrastructure-Based Sensors Augmenting Efficient Autonomous Vehicle Operations: Preprint

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

Jun, Myungsoo; Markel, Anthony J

Autonomous vehicle technology development relies on an on-board network of fused sensor inputs for safe and efficient operation. The fused sensors offer multiple perspectives of similar information aiding in system decision robustness. The high cost of full systems on individual vehicles is seen as a potential barrier to broad adoption and achieving system energy efficiency gains. Since traffic in autonomous vehicle technology development relies on an on-board network of fused sensor inputs for safe and efficient operation. The fused sensors offer multiple perspectives of similar information aiding in system decision robustness. The high cost of full systems on individual vehiclesmore » is seen as a potential barrier to broad adoption and achieving system energy efficiency gains.« less

Gain and power optimization of the wireless optical system with multilevel modulation.

PubMed

Liu, Xian

2008-06-01

When used in an outdoor environment to expedite networking access, the performance of wireless optical communication systems is affected by transmitter sway. In the design of such systems, much attention has been paid to developing power-efficient schemes. However, the bandwidth efficiency is also an important issue. One of the most natural approaches to promote bandwidth efficiency is to use multilevel modulation. This leads to multilevel pulse amplitude modulation in the context of intensity modulation and direct detection. We develop a model based on the four-level pulse amplitude modulation. We show that the model can be formulated as an optimization problem in terms of the transmitter power, bit error probability, transmitter gain, and receiver gain. The technical challenges raised by modeling and solving the problem include the analytical and numerical treatments for the improper integrals of the Gaussian functions coupled with the erfc function. The results demonstrate that, at the optimal points, the power penalty paid to the doubled bandwidth efficiency is around 3 dB.

Decomposing Cost Efficiency in Regional Long-term Care Provision in Japan.

PubMed

Yamauchi, Yasuhiro

2015-07-12

Many developed countries face a growing need for long-term care provision because of population ageing. Japan is one such example, given its population's longevity and low birth rate. In this study, we examine the efficiency of Japan's regional long-term care system in FY2010 by performing a data envelopment analysis, a non-parametric frontier approach, on prefectural data and separating cost efficiency into technical, allocative, and price efficiencies under different average unit costs across regions. In doing so, we elucidate the structure of cost inefficiency by incorporating a method for restricting weight flexibility to avoid unrealistic concerns arising from zero optimal weight. The results indicate that technical inefficiency accounts for the highest share of losses, followed by price inefficiency and allocation inefficiency. Moreover, the majority of technical inefficiency losses stem from labor costs, particularly those for professional caregivers providing institutional services. We show that the largest share of allocative inefficiency losses can also be traced to labor costs for professional caregivers providing institutional services, while the labor provision of in-home care services shows an efficiency gain. However, although none of the prefectures gains efficiency by increasing the number of professional caregivers for institutional services, quite a few prefectures would gain allocative efficiency by increasing capital inputs for institutional services. These results indicate that preferred policies for promoting efficiency might vary from region to region, and thus, policy implications should be drawn with care.

Inverted Ultrathin Organic Solar Cells with a Quasi-Grating Structure for Efficient Carrier Collection and Dip-less Visible Optical Absorption.

PubMed

In, Sungjun; Park, Namkyoo

2016-02-23

We propose a metallic-particle-based two-dimensional quasi-grating structure for application to an organic solar cell. With the use of oblate spheroidal nanoparticles in contact with an anode of inverted, ultrathin organic solar cells (OSCs), the quasi-grating structure offers strong hybridization between localized surface plasmons and plasmonic gap modes leading to broadband (300~800 nm) and uniform (average ~90%) optical absorption spectra. Both strong optical enhancement in extreme confinement within the active layer (90 nm) and improved hole collection are thus realized. A coupled optical-electrical multi-physics optimization shows a large (~33%) enhancement in the optical absorption (corresponding to an absorption efficiency of ~47%, AM1.5G weighted, visible) when compared to a control OSC without the quasi-grating structure. That translates into a significant electrical performance gain of ~22% in short circuit current and ~15% in the power conversion efficiency (PCE), leading to an energy conversion efficiency (~6%) which is comparable to that of optically-thick inverted OSCs (3-7%). Detailed analysis on the influences of mode hybridization to optical field distributions, exciton generation rate, charge carrier collection efficiency and electrical conversion efficiency is provided, to offer an integrated understanding on the coupled optical-electrical optimization of ultrathin OSCs.

Numerical methods for large eddy simulation of acoustic combustion instabilities

NASA Astrophysics Data System (ADS)

Wall, Clifton T.

Acoustic combustion instabilities occur when interaction between the combustion process and acoustic modes in a combustor results in periodic oscillations in pressure, velocity, and heat release. If sufficiently large in amplitude, these instabilities can cause operational difficulties or the failure of combustor hardware. In many situations, the dominant instability is the result of the interaction between a low frequency acoustic mode of the combustor and the large scale hydrodynamics. Large eddy simulation (LES), therefore, is a promising tool for the prediction of these instabilities, since both the low frequency acoustic modes and the large scale hydrodynamics are well resolved in LES. Problems with the tractability of such simulations arise, however, due to the difficulty of solving the compressible Navier-Stokes equations efficiently at low Mach number and due to the large number of acoustic periods that are often required for such instabilities to reach limit cycles. An implicit numerical method for the solution of the compressible Navier-Stokes equations has been developed which avoids the acoustic CFL restriction, allowing for significant efficiency gains at low Mach number, while still resolving the low frequency acoustic modes of interest. In the limit of a uniform grid the numerical method causes no artificial damping of acoustic waves. New, non-reflecting boundary conditions have also been developed for use with the characteristic-based approach of Poinsot and Lele (1992). The new boundary conditions are implemented in a manner which allows for significant reduction of the computational domain of an LES by eliminating the need to perform LES in regions where one-dimensional acoustics significantly affect the instability but details of the hydrodynamics do not. These new numerical techniques have been demonstrated in an LES of an experimental combustor. The new techniques are shown to be an efficient means of performing LES of acoustic combustion instabilities and are shown to accurately predict the occurrence and frequency of the dominant mode of the instability observed in the experiment.

Energy beyond food: foraging theory informs time spent in thermals by a large soaring bird.

PubMed

Shepard, Emily L C; Lambertucci, Sergio A; Vallmitjana, Diego; Wilson, Rory P

2011-01-01

Current understanding of how animals search for and exploit food resources is based on microeconomic models. Although widely used to examine feeding, such constructs should inform other energy-harvesting situations where theoretical assumptions are met. In fact, some animals extract non-food forms of energy from the environment, such as birds that soar in updraughts. This study examined whether the gains in potential energy (altitude) followed efficiency-maximising predictions in the world's heaviest soaring bird, the Andean condor (Vultur gryphus). Animal-attached technology was used to record condor flight paths in three-dimensions. Tracks showed that time spent in patchy thermals was broadly consistent with a strategy to maximise the rate of potential energy gain. However, the rate of climb just prior to leaving a thermal increased with thermal strength and exit altitude. This suggests higher rates of energetic gain may not be advantageous where the resulting gain in altitude would lead to a reduction in the ability to search the ground for food. Consequently, soaring behaviour appeared to be modulated by the need to reconcile differing potential energy and food energy distributions. We suggest that foraging constructs may provide insight into the exploitation of non-food energy forms, and that non-food energy distributions may be more important in informing patterns of movement and residency over a range of scales than previously considered.

Organic field effect transistor with ultra high amplification

NASA Astrophysics Data System (ADS)

Torricelli, Fabrizio

2016-09-01

High-gain transistors are essential for the large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show organic transistors fabricated on plastic foils enabling unipolar amplifiers with ultra-gain. The proposed approach is general and opens up new opportunities for ultra-large signal amplification in organic circuits and sensors.

Robust Optimal Adaptive Control Method with Large Adaptive Gain

NASA Technical Reports Server (NTRS)

Nguyen, Nhan T.

2009-01-01

In the presence of large uncertainties, a control system needs to be able to adapt rapidly to regain performance. Fast adaptation is referred to the implementation of adaptive control with a large adaptive gain to reduce the tracking error rapidly. However, a large adaptive gain can lead to high-frequency oscillations which can adversely affect robustness of an adaptive control law. A new adaptive control modification is presented that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. The modification is based on the minimization of the Y2 norm of the tracking error, which is formulated as an optimal control problem. The optimality condition is used to derive the modification using the gradient method. The optimal control modification results in a stable adaptation and allows a large adaptive gain to be used for better tracking while providing sufficient stability robustness. Simulations were conducted for a damaged generic transport aircraft with both standard adaptive control and the adaptive optimal control modification technique. The results demonstrate the effectiveness of the proposed modification in tracking a reference model while maintaining a sufficient time delay margin.

Mitigating Structural Defects in Droop-Minimizing InGaN/GaN Quantum Well Heterostructures

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

Zhao, Zhibo; Chesin, Jordan; Singh, Akshay

2016-12-01

Modern commercial InGaN/GaN blue LEDs continue to suffer from efficiency droop, a reduction in efficiency with increasing drive current. External quantum efficiency (EQE) typically peaks at low drive currents (< 10 A cm 2) and drops monotonically at higher current densities, falling to <85% of the peak EQE at a drive current of 100 A cm 2. Mitigating droop-related losses will yield tremendous gains in both luminous efficacy (lumens/W) and cost (lumens/$). Such improvements are critical for continued large-scale market penetration of LED technologies, particularly in high-power and high flux per unit area applications. However, device structures that reduce droopmore » typically require higher indium content and are accompanied by a corresponding degradation in material quality which negates the droop improvement via enhanced Shockley-Read-Hall (SRH) recombination. In this work, we use advanced characterization techniques to identify and classify structural defects in InGaN/GaN quantum well (QW) heterostructures that share features with low-droop designs. Using aberration-corrected scanning transmission electron microscopy (C s-STEM), we find the presence of severe well width fluctuations (WWFs) in a number of low droop device architectures. However, the presence of WWFs does not correlate strongly with external quantum efficiency nor defect densities measured via deep level optical spectroscopy (DLOS). Hence, performance losses in the heterostructures of interest are likely dominated by nanoscale point or interfacial defects rather than large-scale extended defects.« less

Feed efficiency - how should it be used for the cow herd?

USDA-ARS?s Scientific Manuscript database

In cows, the most critical factor influencing the output component of efficiency is reproductive rate, and not necessarily weight gain. Thus benefits of selecting animals with desirable measures of feed efficiency on cow efficiency remain to be determined. The feed input component of cow efficiency...

Management and genetic factors affecting efficiency of cattle in a grazing environment

USDA-ARS?s Scientific Manuscript database

Much of current efforts to improve efficiency in cattle use measures of individual feed intake in combination with weight gain as an indication of efficiency. This approach provides pertinent information concerning efficiency during the growing phase, but the relationship to cow efficiency remains t...

Resource Allocation Strategies to Increase the Efficiency and Sustainability of Gavi's Health System Strengthening Grants.

PubMed

Mimche, Honoré; Squires, Ellen; Miangotar, Yodé; Mokdad, Ali; El Bcheraoui, Charbel

2018-05-01

Despite the increase in Health System Strengthening (HSS) grants, there is no consensus among global health actors about how to maximize the efficiency and sustainability of HSS programs and their resulting gains. To formally analyze and compare the efficiency and sustainability of Gavi's HSS grants, we investigated the factors, events and root causes that increased the time and effort needed to implement HSS grants, decreased expected outcomes and threatened the continuity of activities and the sustainability of the results gained through these grants in Cameron and Chad. We conducted 2 retrospective independent evaluations of Gavi's HSS support in Cameroon and Chad using a mixed methodology. We investigated the chain of events and situations that increased the effort and time required to implement the HSS programs, decreased the value of the funds spent and hindered the sustainability of the implemented activities and gains achieved. Root causes affecting the efficiency and sustainability of HSS grants were common to Cameroon and Chad. Weaknesses in health workforce and leadership/governance of the health system in both countries led to interrupting the HSS grants, reprogramming them, almost doubling their implementation period, shifting their focus during implementation toward procurements and service provision, leaving both countries without solid exit plans to maintain the results gained. To increase the efficiency and sustainability of Gavi's HSS grants, recipient countries need to consider health workforce and leadership/governance prior, or in parallel to strengthening other building blocks of their health systems.

Design of energy efficient building with radiant slab cooling

NASA Astrophysics Data System (ADS)

Tian, Zhen

2007-12-01

Air-conditioning comprises a substantial fraction of commercial building energy use because of compressor-driven refrigeration and fan-driven air circulation. Core regions of large buildings require year-round cooling due to heat gains from people, lights and equipment. Negative environmental impacts include CO2 emissions from electric generation and leakage of ozone-depleting refrigerants. Some argue that radiant cooling simultaneously improves building efficiency and occupant thermal comfort, and that current thermal comfort models fail to reflect occupant experience with radiant thermal control systems. There is little field evidence to test these claims. The University of Calgary's Information and Communications Technology (ICT) Building, is a pioneering radiant slab cooling installation in North America. Thermal comfort and energy performance were evaluated. Measurements included: (1) heating and cooling energy use, (2) electrical energy use for lighting and equipment, and (3) indoor temperatures. Accuracy of a whole building energy simulation model was evaluated with these data. Simulation was then used to compare the radiant slab design with a conventional (variable air volume) system. The radiant system energy performance was found to be poorer mainly due to: (1) simultaneous cooling by the slab and heating by other systems, (2) omission of low-exergy (e.g., groundwater) cooling possible with the high cooling water temperatures possible with radiant slabs and (3) excessive solar gain and conductive heat loss due to the wall and fenestration design. Occupant thermal comfort was evaluated through questionnaires and concurrent measurement of workstation comfort parameters. Analysis of 116 sets of data from 82 occupants showed that occupant assessment was consistent with estimates based on current thermal comfort models. The main thermal comfort improvements were reductions in (1) local discomfort from draft and (2) vertical air temperature stratification. The analysis showed that integrated architectural and mechanical design is required to achieve the potential benefits of radiant slab cooling, including: (1) reduction of peak solar gain via windows through (a) avoiding large window-to-wall ratios and/or (b) exterior shading of windows, (2) use of low-quality cooling sources such as cooling towers and ground water, especially in cold, dry climates, and (3) coordination of system control to avoid simultaneous heating and cooling.

OppoRTUnities Abound

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

Deru, Michael

According to the U.S. Energy Information Administration, HVAC accounts for approximately 38 percent of U.S. commercial buildings' primary energy consumption and a slightly higher percentage of their greenhouse-gas emissions. We have seen incredible gains made with lighting, going from incandescent and T12 fluorescent bulbs to high-efficiency LEDS, but there are even greater advances to be made with HVAC. Gains of 20 percent to 30 percent easily can be made by replacing older degraded equipment with new high-efficiency equipment. Even more savings are possible with an integrated engineering approach yielding optimized system designs combined with highly efficient controls.

Improvement of non-key traits in radiata pine breeding programme when long-term economic importance is uncertain.

PubMed

Li, Yongjun; Dungey, Heidi; Yanchuk, Alvin; Apiolaza, Luis A

2017-01-01

Diameter at breast height (DBH), wood density (DEN) and predicted modulus of elasticity (PME) are considered as 'key traits' (KT) in the improvement in radiata pine breeding programmes in New Zealand. Any other traits which are also of interest to radiata pine breeders and forest growers are called 'non-key traits' (NKTs). External resin bleeding (ERB), internal checking (IC), number of heartwood rings (NHR) are three such non-key traits which affect wood quality of radiata pine timber. Economic importance of the KTs and NKTs is hard to define in radiata pine breeding programmes due to long rotation period. Desired-gain index (DGIs) and robust selection were proposed to incorporate NKTs into radiata pine breeding programme in order to deal with the uncertainty of economic importance. Four desired-gain indices A-D were proposed in this study. The desired-gain index A (DGI-A) emphasized growth and led to small decrease in ERB and small increase in IC and NHR. The expected genetic gains of all traits in the desired-gain index B (DGI-B) were in the favourable directions (positive genetic gains in the key traits and negative genetic gains in the non-key traits). The desired-gain index C (DGI-C) placed emphasis on wood density, leading to favourable genetic gain in the NKTs but reduced genetic gains for DBH and PME. The desired-gain index D (DGI-D) exerted a bit more emphasis on the non-key traits, leading large favourable reduction in the non-key traits and lower increase in the key traits compared with the other DGIs. When selecting both the key traits and the non-key traits, the average EBVs of six traits were all in the same directions as the expected genetic gains except for DBH in the DGI-D. When the key traits were measured and selected, internal checking always had a negative (favourable) genetic gain but ERB and NHR had unfavourable genetic gain in the most of time. After removing some individuals with high sensitivity to the change of economic weights, robust desired-gain selection made genetic gains of all the key and non-key traits to move a little bit toward unfavourable directions in the four indices. It is concluded that desired-gain index combined with robust selection concept is an efficient way for selecting the key and non-key traits in radiata pine breeding programmes.

How much is too much assessment? Insight into assessment-driven student learning gains in large-scale undergraduate microbiology courses.

PubMed

Wang, Jack T H; Schembri, Mark A; Hall, Roy A

2013-01-01

Designing and implementing assessment tasks in large-scale undergraduate science courses is a labor-intensive process subject to increasing scrutiny from students and quality assurance authorities alike. Recent pedagogical research has provided conceptual frameworks for teaching introductory undergraduate microbiology, but has yet to define best-practice assessment guidelines. This study assessed the applicability of Biggs' theory of constructive alignment in designing consistent learning objectives, activities, and assessment items that aligned with the American Society for Microbiology's concept-based microbiology curriculum in MICR2000, an introductory microbiology course offered at the University of Queensland, Australia. By improving the internal consistency in assessment criteria and increasing the number of assessment items explicitly aligned to the course learning objectives, the teaching team was able to efficiently provide adequate feedback on numerous assessment tasks throughout the semester, which contributed to improved student performance and learning gains. When comparing the constructively aligned 2011 offering of MICR2000 with its 2010 counterpart, students obtained higher marks in both coursework assignments and examinations as the semester progressed. Students also valued the additional feedback provided, as student rankings for course feedback provision increased in 2011 and assessment and feedback was identified as a key strength of MICR2000. By designing MICR2000 using constructive alignment and iterative assessment tasks that followed a common set of learning outcomes, the teaching team was able to effectively deliver detailed and timely feedback in a large introductory microbiology course. This study serves as a case study for how constructive alignment can be integrated into modern teaching practices for large-scale courses.

Uncertainty quantification of seabed parameters for large data volumes along survey tracks with a tempered particle filter

NASA Astrophysics Data System (ADS)

Dettmer, J.; Quijano, J. E.; Dosso, S. E.; Holland, C. W.; Mandolesi, E.

2016-12-01

Geophysical seabed properties are important for the detection and classification of unexploded ordnance. However, current surveying methods such as vertical seismic profiling, coring, or inversion are of limited use when surveying large areas with high spatial sampling density. We consider surveys based on a source and receiver array towed by an autonomous vehicle which produce large volumes of seabed reflectivity data that contain unprecedented and detailed seabed information. The data are analyzed with a particle filter, which requires efficient reflection-coefficient computation, efficient inversion algorithms and efficient use of computer resources. The filter quantifies information content of multiple sequential data sets by considering results from previous data along the survey track to inform the importance sampling at the current point. Challenges arise from environmental changes along the track where the number of sediment layers and their properties change. This is addressed by a trans-dimensional model in the filter which allows layering complexity to change along a track. Efficiency is improved by likelihood tempering of various particle subsets and including exchange moves (parallel tempering). The filter is implemented on a hybrid computer that combines central processing units (CPUs) and graphics processing units (GPUs) to exploit three levels of parallelism: (1) fine-grained parallel computation of spherical reflection coefficients with a GPU implementation of Levin integration; (2) updating particles by concurrent CPU processes which exchange information using automatic load balancing (coarse grained parallelism); (3) overlapping CPU-GPU communication (a major bottleneck) with GPU computation by staggering CPU access to the multiple GPUs. The algorithm is applied to spherical reflection coefficients for data sets along a 14-km track on the Malta Plateau, Mediterranean Sea. We demonstrate substantial efficiency gains over previous methods. [This research was supported in part by the U.S. Dept of Defense, thought the Strategic Environmental Research and Development Program (SERDP).

Index-antiguided planar waveguide lasers with large mode area

NASA Astrophysics Data System (ADS)

Liu, Yuanye

The on-going research and application interests with high power large-mode-area (LMA) waveguide lasers, especially in fiber geometry, at the beginning of this century drive the development of many novel waveguide designs. Index antiguiding, proposed by Siegman in 2003, is among one of them. The goal for index antiguiding is to introduce transversal modal loss with the relative simple waveguide design while maintain single transverse mode operation for good beam quality. The idea which is selectively support of fundamental mode is facilitated by involving certain level of signal regeneration inside the waveguide core. Since the modal loss is closed associated with waveguide design parameters such as core size and refractive index, the amount of gain inside the core provides active control of transverse modes inside index-antiguiding waveguide. For example, fundamental transverse mode inside such waveguide can be excited and propagate lossless when sufficient optical gain is provided. This often requires doped waveguide core and optical pumping at corresponding absorption band. However, the involvement of optical pumping also has its consequences. Phenomena such as thermal-optic effect and gain spatial hole-burning which are commonly found in bulk lasers request attention when scaling up output power with LMA index-antiguided waveguide amplifiers and resonators. In response, three key challenges of index-antiguided planar waveguide lasers, namely, guiding mechanism, power efficiency and transverse mode discrimination, are analyzed theoretically and experimentally in this dissertation. Experiments are based on two index-antiguided planar waveguide chips, whose core thickness are 220 microm and 400 microm respectively. The material of waveguide core is 1% Neodymium-doped Yttrium Aluminium garnet, or Nd:YAG while the cladding is made from Terbium Gallium garnet, or TGG. Due to the face pumping and limited pump power, it is found, with 220 microm-thick-core chip, that the guidance of the fundamental transverse mode along two orthogonal directions in a transverse plane is different. Along the bounded direction, index antiguiding prevails with negligible thermal refractive focusing while along the unbounded direction, the lasing mode is guided by thermal refractive focusing with negligible quadratic gain focusing. It is also founded that the quadratic thermal focusing will dominate the mode guidance in 220 microm chip with the help of additional pump. All these discovery calls for an active thermal control. The modal discriminative loss, though beneficial for transverse mode control, yet reduces the lasing efficiency. To model it, a 3-D lasing output power calculation model is developed based on spatial rate equations. The simulation results show good agreement with experiment data where slope efficiency curve are measured using multiple output couplers. The 10% slope efficiency with respect to incident pump power is the highest slope efficiency recorded in index-antiguided waveguide continuous-wave lasers. The model indicates more efficient pump absorption can facilitate further power scaling. The role of the modal discriminative loss in transverse mode competition is discussed. A theoretical model based on Rigrod analysis and spatial hole-burning is developed. The simulation shows reasonable agreement with experiment results in both chips. The single fundamental mode operation up to 10 times above the lasing threshold for 220 microm chip is achieved, which is limited by the incident pump power. However, as the core size increases, the modal distributed loss due to the index antiguiding is found to be less effective in transverse mode control. Other modal loss is needed to facilitate the suppression of higher-order modes. Based on the model, a strategy is proposed aiming to maximize the single mode output. It is also noted that the transverse mode competition model is also suitable for other lasers system with well-defined modal loss. Based on the models and experiment data, the index-antiguided planar waveguide lasers are proved to be capable of maintaining large-mode-area single transverse mode operation with the potential of power scaling. However, it is also shown that proper waveguide design is essential. The remaining challenges are the material choices for waveguide fabrication, especially for high power applications.

Improving attention control in dysphoria through cognitive training: transfer effects on working memory capacity and filtering efficiency.

PubMed

Owens, Max; Koster, Ernst H W; Derakshan, Nazanin

2013-03-01

Impaired filtering of irrelevant information from working memory is thought to underlie reduced working memory capacity for relevant information in dysphoria. The current study investigated whether training-related gains in working memory performance on the adaptive dual n-back task could result in improved inhibitory function. Efficacy of training was monitored in a change detection paradigm allowing measurement of a sustained event-related potential asymmetry sensitive to working memory capacity and the efficient filtering of irrelevant information. Dysphoric participants in the training group showed training-related gains in working memory that were accompanied by gains in working memory capacity and filtering efficiency compared to an active control group. Results provide important initial evidence that behavioral performance and neural function in dysphoria can be improved by facilitating greater attentional control. Copyright © 2013 Society for Psychophysiological Research.

The importance of calorimetry for highly-boosted jet substructure

DOE PAGES

Coleman, Evan; Freytsis, Marat; Hinzmann, Andreas; ...

2018-01-09

Here, jet substructure techniques are playing an essential role in exploring the TeV scale at the Large Hadron Collider (LHC), since they facilitate the efficient reconstruction and identification of highly-boosted objects. Both for the LHC and for future colliders, there is a growing interest in using jet substructure methods based only on charged-particle information. The reason is that silicon-based tracking detectors offer excellent granularity and precise vertexing, which can improve the angular resolution on highly-collimated jets and mitigate the impact of pileup. In this paper, we assess how much jet substructure performance degrades by using track-only information, and we demonstratemore » physics contexts in which calorimetry is most beneficial. Specifically, we consider five different hadronic final states - W bosons, Z bosons, top quarks, light quarks, gluons - and test the pairwise discrimination power with a multi-variate combination of substructure observables. In the idealized case of perfect reconstruction, we quantify the loss in discrimination performance when using just charged particles compared to using all detected particles. We also consider the intermediate case of using charged particles plus photons, which provides valuable information about neutral pions. In the more realistic case of a segmented calorimeter, we assess the potential performance gains from improving calorimeter granularity and resolution, comparing a CMS-like detector to more ambitious future detector concepts. Broadly speaking, we find large performance gains from neutral-particle information and from improved calorimetry in cases where jet mass resolution drives the discrimination power, whereas the gains are more modest if an absolute mass scale calibration is not required.« less

The importance of calorimetry for highly-boosted jet substructure

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

Coleman, Evan; Freytsis, Marat; Hinzmann, Andreas

2017-09-25

Jet substructure techniques are playing an essential role in exploring the TeV scale at the Large Hadron Collider (LHC), since they facilitate the efficient reconstruction and identification of highly-boosted objects. Both for the LHC and for future colliders, there is a growing interest in using jet substructure methods based only on charged-particle information. The reason is that silicon-based tracking detectors offer excellent granularity and precise vertexing, which can improve the angular resolution on highly-collimated jets and mitigate the impact of pileup. In this paper, we assess how much jet substructure performance degrades by using track-only information, and we demonstrate physicsmore » contexts in which calorimetry is most beneficial. Specifically, we consider five different hadronic final states - W bosons, Z bosons, top quarks, light quarks, gluons - and test the pairwise discrimination power with a multi-variate combination of substructure observables. In the idealized case of perfect reconstruction, we quantify the loss in discrimination performance when using just charged particles compared to using all detected particles. We also consider the intermediate case of using charged particles plus photons, which provides valuable information about neutral pions. In the more realistic case of a segmented calorimeter, we assess the potential performance gains from improving calorimeter granularity and resolution, comparing a CMS-like detector to more ambitious future detector concepts. Broadly speaking, we find large performance gains from neutral-particle information and from improved calorimetry in cases where jet mass resolution drives the discrimination power, whereas the gains are more modest if an absolute mass scale calibration is not required.« less

The importance of calorimetry for highly-boosted jet substructure

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

Coleman, Evan; Freytsis, Marat; Hinzmann, Andreas

Here, jet substructure techniques are playing an essential role in exploring the TeV scale at the Large Hadron Collider (LHC), since they facilitate the efficient reconstruction and identification of highly-boosted objects. Both for the LHC and for future colliders, there is a growing interest in using jet substructure methods based only on charged-particle information. The reason is that silicon-based tracking detectors offer excellent granularity and precise vertexing, which can improve the angular resolution on highly-collimated jets and mitigate the impact of pileup. In this paper, we assess how much jet substructure performance degrades by using track-only information, and we demonstratemore » physics contexts in which calorimetry is most beneficial. Specifically, we consider five different hadronic final states - W bosons, Z bosons, top quarks, light quarks, gluons - and test the pairwise discrimination power with a multi-variate combination of substructure observables. In the idealized case of perfect reconstruction, we quantify the loss in discrimination performance when using just charged particles compared to using all detected particles. We also consider the intermediate case of using charged particles plus photons, which provides valuable information about neutral pions. In the more realistic case of a segmented calorimeter, we assess the potential performance gains from improving calorimeter granularity and resolution, comparing a CMS-like detector to more ambitious future detector concepts. Broadly speaking, we find large performance gains from neutral-particle information and from improved calorimetry in cases where jet mass resolution drives the discrimination power, whereas the gains are more modest if an absolute mass scale calibration is not required.« less

Predicting risk of substantial weight gain in German adults-a multi-center cohort approach.

PubMed

Bachlechner, Ursula; Boeing, Heiner; Haftenberger, Marjolein; Schienkiewitz, Anja; Scheidt-Nave, Christa; Vogt, Susanne; Thorand, Barbara; Peters, Annette; Schipf, Sabine; Ittermann, Till; Völzke, Henry; Nöthlings, Ute; Neamat-Allah, Jasmine; Greiser, Karin-Halina; Kaaks, Rudolf; Steffen, Annika

2017-08-01

A risk-targeted prevention strategy may efficiently utilize limited resources available for prevention of overweight and obesity. Likewise, more efficient intervention trials could be designed if selection of subjects was based on risk. The aim of the study was to develop a risk score predicting substantial weight gain among German adults. We developed the risk score using information on 15 socio-demographic, dietary and lifestyle factors from 32 204 participants of five population-based German cohort studies. Substantial weight gain was defined as gaining ≥10% of weight between baseline and follow-up (>6 years apart). The cases were censored according to the theoretical point in time when the threshold of 10% baseline-based weight gain was crossed assuming linearity of weight gain. Beta coefficients derived from proportional hazards regression were used as weights to compute the risk score as a linear combination of the predictors. Cross-validation was used to evaluate the score's discriminatory accuracy. The cross-validated c index (95% CI) was 0.71 (0.67-0.75). A cutoff value of ≥475 score points yielded a sensitivity of 71% and a specificity of 63%. The corresponding positive and negative predictive values were 10.4% and 97.6%, respectively. The proposed risk score may support healthcare providers in decision making and referral and facilitate an efficient selection of subjects into intervention trials. © The Author 2016. Published by Oxford University Press on behalf of the European Public Health Association.

Predicting risk of substantial weight gain in German adults—a multi-center cohort approach

PubMed Central

Bachlechner, Ursula; Boeing, Heiner; Haftenberger, Marjolein; Schienkiewitz, Anja; Scheidt-Nave, Christa; Vogt, Susanne; Thorand, Barbara; Peters, Annette; Schipf, Sabine; Ittermann, Till; Völzke, Henry; Nöthlings, Ute; Neamat-Allah, Jasmine; Greiser, Karin-Halina; Kaaks, Rudolf

2017-01-01

Abstract Background A risk-targeted prevention strategy may efficiently utilize limited resources available for prevention of overweight and obesity. Likewise, more efficient intervention trials could be designed if selection of subjects was based on risk. The aim of the study was to develop a risk score predicting substantial weight gain among German adults. Methods We developed the risk score using information on 15 socio-demographic, dietary and lifestyle factors from 32 204 participants of five population-based German cohort studies. Substantial weight gain was defined as gaining ≥10% of weight between baseline and follow-up (>6 years apart). The cases were censored according to the theoretical point in time when the threshold of 10% baseline-based weight gain was crossed assuming linearity of weight gain. Beta coefficients derived from proportional hazards regression were used as weights to compute the risk score as a linear combination of the predictors. Cross-validation was used to evaluate the score’s discriminatory accuracy. Results The cross-validated c index (95% CI) was 0.71 (0.67–0.75). A cutoff value of ≥475 score points yielded a sensitivity of 71% and a specificity of 63%. The corresponding positive and negative predictive values were 10.4% and 97.6%, respectively. Conclusions The proposed risk score may support healthcare providers in decision making and referral and facilitate an efficient selection of subjects into intervention trials. PMID:28013243

Decomposing Cost Efficiency in Regional Long-term Care Provision in Japan

PubMed Central

Yamauchi, Yasuhiro

2016-01-01

Many developed countries face a growing need for long-term care provision because of population ageing. Japan is one such example, given its population's longevity and low birth rate. In this study, we examine the efficiency of Japan's regional long-term care system in FY2010 by performing a data envelopment analysis, a non-parametric frontier approach, on prefectural data and separating cost efficiency into technical, allocative, and price efficiencies under different average unit costs across regions. In doing so, we elucidate the structure of cost inefficiency by incorporating a method for restricting weight flexibility to avoid unrealistic concerns arising from zero optimal weight. The results indicate that technical inefficiency accounts for the highest share of losses, followed by price inefficiency and allocation inefficiency. Moreover, the majority of technical inefficiency losses stem from labor costs, particularly those for professional caregivers providing institutional services. We show that the largest share of allocative inefficiency losses can also be traced to labor costs for professional caregivers providing institutional services, while the labor provision of in-home care services shows an efficiency gain. However, although none of the prefectures gains efficiency by increasing the number of professional caregivers for institutional services, quite a few prefectures would gain allocative efficiency by increasing capital inputs for institutional services. These results indicate that preferred policies for promoting efficiency might vary from region to region, and thus, policy implications should be drawn with care. PMID:26493427

Development of an X-Band 50 MW Multiple Beam Klystron

NASA Astrophysics Data System (ADS)

Song, Liqun; Ferguson, Patrick; Ives, R. Lawrence; Miram, George; Marsden, David; Mizuhara, Max

2003-12-01

Calabazas Creek Research, Inc. is developing an X-band 50 MW multiple beam klystron (MBK) on a DOE SBIR Phase II grant. The electrical design and preliminary mechanical design were completed on the Phase I. This MBK consists of eight discrete klystron circuits driven by eight electron beams located symmetrically on a circle with a radius of 6.3 cm. Each beam operates at 190 kV and 66 A. The eight beam electron gun is in development on a DOE SBIR Phase II grant. Each circuit consists of an input cavity, two gain cavities, three penultimate cavities, and a three cavity output circuit operating in the PI/2 mode. Ring resonators were initially proposed for the complete circuit; however, low beam — wave interaction resulted in the necessity to use discrete cavities for all eight circuits. The input cavities are coupled via hybrid waveguides to ensure constant drive power amplitude and phase. The output circuits can either be combined using compact waveguide twists driving a TE01 high power window or combined into a TM04 mode converter driving the same TE01 window. The gain and efficiency for a single circuit has been optimized using KLSC, a 2 1/2D large signal klystron code. Simulations for a single circuit predict an efficiency of 53% for a single output cavity and 55% for the three cavity output resonator. The total RF output power for this MBK is 55 MW. During the Phase II emphasis will be given to cost reduction techniques resulting in a robust — high efficient — long life high power amplifier.

Differential effects of high-fat diets varying in fatty acid composition on the efficiency of lean and fat tissue deposition during weight recovery after low food intake.

PubMed

Dulloo, A G; Mensi, N; Seydoux, J; Girardier, L

1995-02-01

The energetics of body weight recovery after low food intake was examined in the rat during refeeding for 2 weeks with isocaloric amounts of high-fat (HF) diets providing 50% of energy as either lard, coconut oil, olive oil, safflower oil, menhaden fish oil, or a mixture of all these fat types. The results indicate that for both body fat and protein, the efficiency of deposition was dependent on the dietary fat type. The most striking differences were found (1) between diets rich in n-3 and n-6 polyunsaturated fatty acids (PUFA), with the diet high in fish oil resulting in a greater body fat deposition and lower protein gain than the diet high in safflower oil; and (2) between diets rich in long-chain (LCT) and medium-chain triglycerides (MCT), with the diet high in lard resulting in a greater gain in both body fat and protein than the diet high in coconut oil. Furthermore, the diet high in olive oil (a monounsaturated fat) and the mixed-fat diet (containing all fat types) were found to be similar to the fish oil diet in that the efficiency of fat deposition was greater (and that of protein gain lower) than with the diet high in safflower oil. Neither the efficiency of fat gain nor that of protein gain were found to correlate with fasting plasma insulin, the insulin to glucose ratio, or plasma lipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficient Estimation of the Standardized Value

ERIC Educational Resources Information Center

Longford, Nicholas T.

2009-01-01

We derive an estimator of the standardized value which, under the standard assumptions of normality and homoscedasticity, is more efficient than the established (asymptotically efficient) estimator and discuss its gains for small samples. (Contains 1 table and 3 figures.)

Non-Geiger-Mode Single-Photon Avalanche Detector with Low Excess Noise

NASA Technical Reports Server (NTRS)

Zhao, Kai; Lo, YuHwa; Farr, William

2010-01-01

This design constitutes a self-resetting (gain quenching), room-temperature operational semiconductor single-photon-sensitive detector that is sensitive to telecommunications optical wavelengths and is scalable to large areas (millimeter diameter) with high bandwidth and efficiencies. The device can detect single photons at a 1,550-nm wavelength at a gain of 1 x 10(exp 6). Unlike conventional single photon avalanche detectors (SPADs), where gain is an extremely sensitive function to the bias voltage, the multiplication gain of this device is stable at 1 x 10(exp 6) over a wide range of bias from 30.2 to 30.9 V. Here, the multiplication gain is defined as the total number of charge carriers contained in one output pulse that is triggered by the absorption of a single photon. The statistics of magnitude of output signals also shows that the device has a very narrow pulse height distribution, which demonstrates a greatly suppressed gain fluctuation. From the histograms of both pulse height and pulse charge, the equivalent gain variance (excess noise) is between 1.001 and 1.007 at a gain of 1 x 10(exp 6). With these advantages, the device holds promise to function as a PMT-like photon counter at a 1,550- nm wavelength. The epitaxial layer structure of the device allows photons to be absorbed in the InGaAs layer, generating electron/hole (e-h) pairs. Driven by an electrical field in InGaAs, electrons are collected at the anode while holes reach the multiplication region (InAlAs p-i-n structure) and trigger the avalanche process. As a result, a large number of e-h pairs are created, and the holes move toward the cathode. Holes created by the avalanche process gain large kinetic energy through the electric field, and are considered hot. These hot holes are cooled as they travel across a p -InAlAs low field region, and are eventually blocked by energy barriers formed by the InGaAsP/ InAlAs heterojunctions. The composition of the InGaAsP alloy was chosen to have an 80 meV valance band offset with InAlAs, which is high enough to hinder the transport of the already cooled holes. Being stopped by the energy barrier, holes are accumulated at the junctions to shield the electric field, resulting in a decrease of the electric field in the multiplication region. Because the impact ionization rate is extremely sensitive to the magnitude of the electric field, the field-screening effect drastically reduces the impact ionization rate and quenches the output signals. After the avalanche pulse signal is self-quenched, the accumulated holes at the InGaAsP/ InAlAs interface escape the energy barrier through thermal excitation and tunneling and finally leave the device. The device is thus reset and ready for subsequent photon detection. This recovery time is controlled by the height of the energy barrier and the hole-cooling rate.

Performance of Small Pore Microchannel Plates

NASA Technical Reports Server (NTRS)

Siegmund, O. H. W.; Gummin, M. A.; Ravinett, T.; Jelinsky, S. R.; Edgar, M.

1995-01-01

Small pore size microchannel plates (MCP's) are needed to satisfy the requirements for future high resolution small and large format detectors for astronomy. MCP's with pore sizes in the range 5 micron to 8 micron are now being manufactured, but they are of limited availability and are of small size. We have obtained sets of Galileo 8 micron and 6.5 micron MCP's, and Philips 6 micron and 7 micron pore MCP's, and compared them to our larger pore MCP Z stacks. We have tested back to back MCP stacks of four of these MCP's and achieved gains greater than 2 x 1O(exp 7) with pulse height distributions of less than 40% FWHM, and background rates of less than 0.3 events sec(exp -1) cm(exp -2). Local counting rates up to approx. 100 events/pore/sec have been attained with little drop of the MCP gain. The bare MCP quantum efficiencies are somewhat lower than those expected, however. Flat field images are characterized by an absence of MCP fixed pattern noise.

Reflex ring laser amplifier system

DOEpatents

Summers, M.A.

1983-08-31

The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

A filterless, visible-blind, narrow-band, and near-infrared photodetector with a gain

NASA Astrophysics Data System (ADS)

Shen, Liang; Zhang, Yang; Bai, Yang; Zheng, Xiaopeng; Wang, Qi; Huang, Jinsong

2016-06-01

In many applications of near-infrared (NIR) light detection, a band-pass filter is needed to exclude the noise caused by visible light. Here, we demonstrate a filterless, visible-blind, narrow-band NIR photodetector with a full-width at half-maximum of <50 nm for the response spectrum. These devices have a thick (>4 μm) nanocomposite absorbing layers made of polymer-fullerene:lead sulfide (PbS) quantum dots (QDs). The PbS QDs yield a photoconductive gain due to their hole-trapping effect, which effectively enhances both the responsivity and the visible rejection ratio of the external quantum efficiency by >10 fold compared to those without PbS QDs. Encouragingly, the inclusion of the PbS QDs does not increase the device noise. We directly measured a noise equivalent power (NEP) of 6.1 pW cm-2 at 890 nm, and a large linear dynamic range (LDR) over 11 orders of magnitude. The highly sensitive visible-blind NIR narrow-band photodetectors may find applications in biomedical engineering.

Concurrent computation of attribute filters on shared memory parallel machines.

PubMed

Wilkinson, Michael H F; Gao, Hui; Hesselink, Wim H; Jonker, Jan-Eppo; Meijster, Arnold

2008-10-01

Morphological attribute filters have not previously been parallelized, mainly because they are both global and non-separable. We propose a parallel algorithm that achieves efficient parallelism for a large class of attribute filters, including attribute openings, closings, thinnings and thickenings, based on Salembier's Max-Trees and Min-trees. The image or volume is first partitioned in multiple slices. We then compute the Max-trees of each slice using any sequential Max-Tree algorithm. Subsequently, the Max-trees of the slices can be merged to obtain the Max-tree of the image. A C-implementation yielded good speed-ups on both a 16-processor MIPS 14000 parallel machine, and a dual-core Opteron-based machine. It is shown that the speed-up of the parallel algorithm is a direct measure of the gain with respect to the sequential algorithm used. Furthermore, the concurrent algorithm shows a speed gain of up to 72 percent on a single-core processor, due to reduced cache thrashing.

Distributed feedback interband cascade lasers with top grating and corrugated sidewalls

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

Xie, Feng; Stocker, Michael; Pham, John

Distributed feedback (DFB) interband cascade lasers (ICLs) with a 1st order top surface grating were designed and fabricated. Partially corrugated sidewalls were implemented to suppress high order lateral modes. The DFB ICLs have 4 mm long and 4.5 mu m wide ridge waveguides and are mounted epi-up on AlN submounts. We demonstrated a continuous-wave (CW) DFB ICL, from a first wafer which has a large detuning of the gain peak from the DFB wavelength, with a side mode suppression ratio of 30 dB. With proper matching of grating feedback and the gain peak wavelength for the second wafer, a DFBmore » ICL was demonstrated with a maximum CW output power and a maximum wall plug efficiency reaching 42 mW and 2%, respectively, at 25 degrees C. The lasing wavelengths of both lasers are around 3.3 mu m at 25 degrees C. Published by AIP Publishing.« less

Photosynthesis solutions to enhance productivity.

PubMed

Foyer, Christine H; Ruban, Alexander V; Nixon, Peter J

2017-09-26

The concept that photosynthesis is a highly inefficient process in terms of conversion of light energy into biomass is embedded in the literature. It is only in the past decade that the processes limiting photosynthetic efficiency have been understood to an extent that allows a step change in our ability to manipulate light energy assimilation into carbon gain. We can therefore envisage that future increases in the grain yield potential of our major crops may depend largely on increasing the efficiency of photosynthesis. The papers in this issue provide new insights into the nature of current limitations on photosynthesis and identify new targets that can be used for crop improvement, together with information on the impacts of a changing environment on the productivity of photosynthesis on land and in our oceans.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).

Hybrid discrete/continuum algorithms for stochastic reaction networks

DOE PAGES

Safta, Cosmin; Sargsyan, Khachik; Debusschere, Bert; ...

2014-10-22

Direct solutions of the Chemical Master Equation (CME) governing Stochastic Reaction Networks (SRNs) are generally prohibitively expensive due to excessive numbers of possible discrete states in such systems. To enhance computational efficiency we develop a hybrid approach where the evolution of states with low molecule counts is treated with the discrete CME model while that of states with large molecule counts is modeled by the continuum Fokker-Planck equation. The Fokker-Planck equation is discretized using a 2nd order finite volume approach with appropriate treatment of flux components to avoid negative probability values. The numerical construction at the interface between the discretemore » and continuum regions implements the transfer of probability reaction by reaction according to the stoichiometry of the system. As a result, the performance of this novel hybrid approach is explored for a two-species circadian model with computational efficiency gains of about one order of magnitude.« less

Design of a Variational Multiscale Method for Turbulent Compressible Flows

NASA Technical Reports Server (NTRS)

Diosady, Laslo Tibor; Murman, Scott M.

2013-01-01

A spectral-element framework is presented for the simulation of subsonic compressible high-Reynolds-number flows. The focus of the work is maximizing the efficiency of the computational schemes to enable unsteady simulations with a large number of spatial and temporal degrees of freedom. A collocation scheme is combined with optimized computational kernels to provide a residual evaluation with computational cost independent of order of accuracy up to 16th order. The optimized residual routines are used to develop a low-memory implicit scheme based on a matrix-free Newton-Krylov method. A preconditioner based on the finite-difference diagonalized ADI scheme is developed which maintains the low memory of the matrix-free implicit solver, while providing improved convergence properties. Emphasis on low memory usage throughout the solver development is leveraged to implement a coupled space-time DG solver which may offer further efficiency gains through adaptivity in both space and time.

A Comparative Study of Power Supply Architectures In Wireless Electric Vehicle Charging Systems

NASA Astrophysics Data System (ADS)

Esteban, Bryan

Wireless inductive power transfer is a transformational and disruptive technology that enables the reliable and efficient transfer of electrical power over large air gaps for a host of unique applications. One such application that is now gaining much momentum worldwide is the wireless charging of electric vehicles (EVs). This thesis examines two of the primary power supply topologies being predominantly used for EV charging, namely the SLC and the LCL resonant full bridge inverter topologies. The study of both of these topologies is presented in the context of designing a 3 kW, primary side controlled, wireless EV charger with nominal operating parameters of 30 kHz centre frequency and range of coupling in the neighborhood of .18-.26. A comparison of both topologies is made in terms of their complexity, cost, efficiency, and power quality. The aim of the study is to determine which topology is better for wireless EV charging.

PLUM: Parallel Load Balancing for Adaptive Unstructured Meshes

NASA Technical Reports Server (NTRS)

Oliker, Leonid; Biswas, Rupak; Saini, Subhash (Technical Monitor)

1998-01-01

Mesh adaption is a powerful tool for efficient unstructured-grid computations but causes load imbalance among processors on a parallel machine. We present a novel method called PLUM to dynamically balance the processor workloads with a global view. This paper presents the implementation and integration of all major components within our dynamic load balancing strategy for adaptive grid calculations. Mesh adaption, repartitioning, processor assignment, and remapping are critical components of the framework that must be accomplished rapidly and efficiently so as not to cause a significant overhead to the numerical simulation. A data redistribution model is also presented that predicts the remapping cost on the SP2. This model is required to determine whether the gain from a balanced workload distribution offsets the cost of data movement. Results presented in this paper demonstrate that PLUM is an effective dynamic load balancing strategy which remains viable on a large number of processors.

Technical and Economic Evaluation of Advanced Air Cargo Systems

NASA Technical Reports Server (NTRS)

Whitehead, A. H., Jr.

1978-01-01

The current air cargo environment and the relevance of advanced technology aircraft in enhancing the efficiency of the 1990 air cargo system are discussed. NASA preliminary design studies are shown to indicate significant potential gains in aircraft efficiency and operational economics for future freighter concepts. Required research and technology elements are outlined to develop a better base for evaluating advanced design concepts. Current studies of the market operation are reviewed which will develop design criteria for a future dedicated cargo transport. Design features desirable in an all-freighter design are reviewed. NASA-sponsored studies of large, distributed-load freighters are reviewed and these designs are compared to current wide-body aircraft. These concepts vary in gross takeoff weight from 0.5 Gg (one million lbs.) to 1.5 Gg (three million lbs.) and are found to exhibit economic advantages over conventional design concepts.

Photosynthesis solutions to enhance productivity

PubMed Central

2017-01-01

The concept that photosynthesis is a highly inefficient process in terms of conversion of light energy into biomass is embedded in the literature. It is only in the past decade that the processes limiting photosynthetic efficiency have been understood to an extent that allows a step change in our ability to manipulate light energy assimilation into carbon gain. We can therefore envisage that future increases in the grain yield potential of our major crops may depend largely on increasing the efficiency of photosynthesis. The papers in this issue provide new insights into the nature of current limitations on photosynthesis and identify new targets that can be used for crop improvement, together with information on the impacts of a changing environment on the productivity of photosynthesis on land and in our oceans. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’. PMID:28808094

Climbing plants in a temperate rainforest understorey: searching for high light or coping with deep shade?

PubMed

Valladares, Fernando; Gianoli, Ernesto; Saldaña, Alfredo

2011-08-01

While the climbing habit allows vines to reach well-lit canopy areas with a minimum investment in support biomass, many of them have to survive under the dim understorey light during certain stages of their life cycle. But, if the growth/survival trade-off widely reported for trees hold for climbing plants, they cannot maximize both light-interception efficiency and shade avoidance (i.e. escaping from the understorey). The seven most important woody climbers occurring in a Chilean temperate evergreen rainforest were studied with the hypothesis that light-capture efficiency of climbers would be positively associated with their abundance in the understorey. Species abundance in the understorey was quantified from their relative frequency and density in field plots, the light environment was quantified by hemispherical photography, the photosynthetic response to light was measured with portable gas-exchange analyser, and the whole shoot light-interception efficiency and carbon gain was estimated with the 3-D computer model Y-plant. Species differed in specific leaf area, leaf mass fraction, above ground leaf area ratio, light-interception efficiency and potential carbon gain. Abundance of species in the understorey was related to whole shoot features but not to leaf level features such as specific leaf area. Potential carbon gain was inversely related to light-interception efficiency. Mutual shading among leaves within a shoot was very low (<20 %). The abundance of climbing plants in this southern rainforest understorey was directly related to their capacity to intercept light efficiently but not to their potential carbon gain. The most abundant climbers in this ecosystem match well with a shade-tolerance syndrome in contrast to the pioneer-like nature of climbers observed in tropical studies. The climbers studied seem to sacrifice high-light searching for coping with the dim understorey light.

ARECIBO PULSAR SURVEY USING ALFA: PROBING RADIO PULSAR INTERMITTENCY AND TRANSIENTS

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

Deneva, J. S.; Cordes, J. M.; McLaughlin, M. A.

We present radio transient search algorithms, results, and statistics from the ongoing Arecibo Pulsar ALFA (PALFA) survey of the Galactic plane. We have discovered seven objects through a search for isolated dispersed pulses. All of these objects are Galactic and have measured periods between 0.4 and 4.7 s. One of the new discoveries has a duty cycle of 0.01%, smaller than that of any other radio pulsar. We discuss the impact of selection effects on the detectability and classification of intermittent sources, and compare the efficiencies of periodicity and single-pulse (SP) searches for various pulsar classes. For some cases wemore » find that the apparent intermittency is likely to be caused by off-axis detection or a short time window that selects only a few bright pulses and favors detection with our SP algorithm. In other cases, the intermittency appears to be intrinsic to the source. No transients were found with DMs large enough to require that they originate from sources outside our Galaxy. Accounting for the on-axis gain of the ALFA system, as well as the low gain but large solid-angle coverage of far-out sidelobes, we use the results of the survey so far to place limits on the amplitudes and event rates of transients of arbitrary origin.« less

Effect of cull potatoes in the diet for finishing Belgian Blue double-muscled cows.

PubMed

Fiems, L O; De Boever, J L; Vanacker, J M; De Brabander, D L

2013-01-01

The use of culled potatoes was investigated in Belgian Blue double-muscled finishing cows, confined in tie stalls. The control diet (Treatment 1) consisted of concentrate and maize silage (50/50 on a dry matter (DM) basis). Potatoes either replaced 60% maize silage (Treatment 2) or 60% concentrate (Treatment 3). Diets were formulated to be isocaloric and isonitrogenous. They were fed ad libitum. Approximately 18 kg potatoes were fed daily in Treatments 2 and 3. Daily gain was not significantly altered; it decreased from 1.09 kg (Treatment 1) to 1.04 kg (Treatment 2) or increased to 1.20 kg (Treatment 3), although potatoes stimulated DM intake by 5% to 8% (P < 0.05). Feed conversion was unaffected in comparison with the control diet, when expressed in terms of DM, but energy efficiency (MJ/kg live weight gain) was substantially lower for Treatment 2 compared with Treatment 1 (89.9 v. 79.0; P = 0.046). Carcass weight, grading and composition were not affected by treatments, but potatoes increased dressing percentage (P = 0.009). Treatment had no significant effect on meat quality parameters. However, potatoes (Treatments 2 and 3) tended to decrease moisture content (P = 0.090) and tended to increase drip loss (P = 0.059) compared with Treatment 1. Because of a better animal performance and a lower feed cost, it is most appropriate to use potatoes as a replacement for concentrate. Feeding large amounts of potatoes besides concentrate may have an adverse effect on the fibrousness of the diet, resulting in a tendency (-5%) for a reduced daily gain and a lower energy efficiency (P < 0.05).

Challenges in measuring feed efficiency

USDA-ARS?s Scientific Manuscript database

The term feed efficiency is vague, and is defined differently by people. Historically, feed efficiency has been defined as the feed:gain (F:G) ratio or the inverse (G:F). Indexes have been developed to rank animals for feed efficiency. These indexes include residual feed intake (RFI) and residual...

10J water-cooled DPSSL system based on Yb:YAG crystal edge-cladded by Cr:YAG ceramics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zheng, Jian-Gang; Yan, Xiongwei; Jiang, Xinying; Wang, Zhenguo; Li, Mingzhong; Zhang, Jun; Zhu, Qihua; Zheng, Wanguo

2017-05-01

Laser Inertial Fusion Energy (IFE) has been attracting the interests of the researchers around the world, because of the promising to the future energy. The Yb:YAG was broadly used in the research field of high-peak power and large energy laser with repetition-rate for IFE because of its outstanding performance, including significant thermal and mechanical capacities, long upper energy level lifetime, high quantum efficiency and highly doping capacity. But it exhibits high saturation fluence at room temperature because of the small emission and absorption cross-section. And at the same time this gain material exhibits self-absorption of laser because of the thermal population at lower laser level at room temperature. Ant it appears to have been solved by means of the cryogenic temperature, but the total efficiency of the laser system will be decreased as the use of cryogenic temperature. The amplified spontaneous emission (ASE) effect of the amplifier can be relaxed by means of edge-cladded absorption material. And the difficulties of edge cladding can be will solved as the emergence of ceramics. But at present the ceramics exhibits high scattering and many disfigurements, which limited the application in the high-power large-energy laser system. So the edge-cladding of Yb:YAG crystal will be a key issue for solution the ASE in amplifier. In this paper, we will introduce a 10J water-cooled DPSSL system, based on Yb:YAG crystal at room temperature. In this system a new edge cladding method has been used, that the Yb:YAG crystal was edge cladded by Cr:YAG ceramics, which was used as the absorption material of ASE. The amplifier was an active mirror water-cooled room temperature amplifier. With the help of this edge cladding the ASE has been lowered, and about 5 times small signal gain has been obtained in a single pass amplification, which was much higher than the earlier of 2 times. And the wavefront aberrance of the laser beam was also reduced due to the thermal equilibrium between the edge cladding and the gain region. the amplifiers can be stably operated under 10Hz. Finally the output of the laser system was about 7.15J@10Hz and 10.8J@1-2Hz. The total optical-to-optical efficiency was about 8.3% for 1-2Hz (under the condition of 120kW/1ms pumping, 880mJ input and 10.8J output) and 5.6% for 10Hz.

Jimena: efficient computing and system state identification for genetic regulatory networks.

PubMed

Karl, Stefan; Dandekar, Thomas

2013-10-11

Boolean networks capture switching behavior of many naturally occurring regulatory networks. For semi-quantitative modeling, interpolation between ON and OFF states is necessary. The high degree polynomial interpolation of Boolean genetic regulatory networks (GRNs) in cellular processes such as apoptosis or proliferation allows for the modeling of a wider range of node interactions than continuous activator-inhibitor models, but suffers from scaling problems for networks which contain nodes with more than ~10 inputs. Many GRNs from literature or new gene expression experiments exceed those limitations and a new approach was developed. (i) As a part of our new GRN simulation framework Jimena we introduce and setup Boolean-tree-based data structures; (ii) corresponding algorithms greatly expedite the calculation of the polynomial interpolation in almost all cases, thereby expanding the range of networks which can be simulated by this model in reasonable time. (iii) Stable states for discrete models are efficiently counted and identified using binary decision diagrams. As application example, we show how system states can now be sampled efficiently in small up to large scale hormone disease networks (Arabidopsis thaliana development and immunity, pathogen Pseudomonas syringae and modulation by cytokinins and plant hormones). Jimena simulates currently available GRNs about 10-100 times faster than the previous implementation of the polynomial interpolation model and even greater gains are achieved for large scale-free networks. This speed-up also facilitates a much more thorough sampling of continuous state spaces which may lead to the identification of new stable states. Mutants of large networks can be constructed and analyzed very quickly enabling new insights into network robustness and behavior.

Multi-Depth-Map Raytracing for Efficient Large-Scene Reconstruction.

PubMed

Arikan, Murat; Preiner, Reinhold; Wimmer, Michael

2016-02-01

With the enormous advances of the acquisition technology over the last years, fast processing and high-quality visualization of large point clouds have gained increasing attention. Commonly, a mesh surface is reconstructed from the point cloud and a high-resolution texture is generated over the mesh from the images taken at the site to represent surface materials. However, this global reconstruction and texturing approach becomes impractical with increasing data sizes. Recently, due to its potential for scalability and extensibility, a method for texturing a set of depth maps in a preprocessing and stitching them at runtime has been proposed to represent large scenes. However, the rendering performance of this method is strongly dependent on the number of depth maps and their resolution. Moreover, for the proposed scene representation, every single depth map has to be textured by the images, which in practice heavily increases processing costs. In this paper, we present a novel method to break these dependencies by introducing an efficient raytracing of multiple depth maps. In a preprocessing phase, we first generate high-resolution textured depth maps by rendering the input points from image cameras and then perform a graph-cut based optimization to assign a small subset of these points to the images. At runtime, we use the resulting point-to-image assignments (1) to identify for each view ray which depth map contains the closest ray-surface intersection and (2) to efficiently compute this intersection point. The resulting algorithm accelerates both the texturing and the rendering of the depth maps by an order of magnitude.

Calculation of single-pass gain for laser ceramics with losses

NASA Astrophysics Data System (ADS)

Vatnik, S. M.

2018-04-01

Rate equations describing the single-pass gain in an active medium with losses are analytically solved. The found relations illustrate the dependences of the amplification efficiency of Nd : YAG ceramics on the pump power density and specific losses. It is concluded that specific losses can be estimated from comparative measurements of unsaturated and saturated gains.

Jet engine performance enhancement through use of a wave-rotor topping cycle

NASA Technical Reports Server (NTRS)

Wilson, Jack; Paxson, Daniel E.

1993-01-01

A simple model is used to calculate the thermal efficiency and specific power of simple jet engines and jet engines with a wave-rotor topping cycle. The performance of the wave rotor is based on measurements from a previous experiment. Applied to the case of an aircraft flying at Mach 0.8, the calculations show that an engine with a wave rotor topping cycle may have gains in thermal efficiency of approximately 1 to 2 percent and gains in specific power of approximately 10 to 16 percent over a simple jet engine with the same overall compression ratio. Even greater gains are possible if the wave rotor's performance can be improved.

V-Assembly Dual-Head Efficient Resonator (VADER) for Remote Sensing Applications

NASA Technical Reports Server (NTRS)

Coyle, D. Barry; Kay, Richard B.; Stysley, Paul R.; Clark, Greg; Poulios, Demetrios; Frederickson, Robert; Blalock, Gordon; Arnold, Ed; Cory, Ken

2011-01-01

The V-Assembly Dual-head Efficient Resonator (VADER) is a diode pumped, Nd:YAG, Q-switched, positive branch unstable resonator that employs a split laser gain module designed for optimal efficiency and thermal lensing compensation.

Coherence switching of a vertical-cavity semiconductor-laser for multimode biomedical imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Cao, Hui; Knitter, Sebastian; Liu, Changgeng; Redding, Brandon; Khokha, Mustafa Kezar; Choma, Michael Andrew

2017-02-01

Speckle formation is a limiting factor when using coherent sources for imaging and sensing, but can provide useful information about the motion of an object. Illumination sources with tunable spatial coherence are therefore desirable as they can offer both speckled and speckle-free images. Efficient methods of coherence switching have been achieved with a solid-state degenerate laser, and here we demonstrate a semiconductor-based degenerate laser system that can be switched between a large number of mutually incoherent spatial modes and few-mode operation. Our system is designed around a semiconductor gain element, and overcomes barriers presented by previous low spatial coherence lasers. The gain medium is an electrically-pumped vertical external cavity surface emitting laser (VECSEL) with a large active area. The use of a degenerate external cavity enables either distributing the laser emission over a large ( 1000) number of mutually incoherent spatial modes or concentrating emission to few modes by using a pinhole in the Fourier plane of the self-imaging cavity. To demonstrate the unique potential of spatial coherence switching for multimodal biomedical imaging, we use both low and high spatial coherence light generated by our VECSEL-based degenerate laser for imaging embryo heart function in Xenopus, an important animal model of heart disease. The low-coherence illumination is used for high-speed (100 frames per second) speckle-free imaging of dynamic heart structure, while the high-coherence emission is used for laser speckle contrast imaging of the blood flow.

Improving breeding efficiency in potato using molecular and quantitative genetics.

PubMed

Slater, Anthony T; Cogan, Noel O I; Hayes, Benjamin J; Schultz, Lee; Dale, M Finlay B; Bryan, Glenn J; Forster, John W

2014-11-01

Potatoes are highly heterozygous and the conventional breeding of superior germplasm is challenging, but use of a combination of MAS and EBVs can accelerate genetic gain. Cultivated potatoes are highly heterozygous due to their outbreeding nature, and suffer acute inbreeding depression. Modern potato cultivars also exhibit tetrasomic inheritance. Due to this genetic heterogeneity, the large number of target traits and the specific requirements of commercial cultivars, potato breeding is challenging. A conventional breeding strategy applies phenotypic recurrent selection over a number of generations, a process which can take over 10 years. Recently, major advances in genetics and molecular biology have provided breeders with molecular tools to accelerate gains for some traits. Marker-assisted selection (MAS) can be effectively used for the identification of major genes and quantitative trait loci that exhibit large effects. There are also a number of complex traits of interest, such as yield, that are influenced by a large number of genes of individual small effect where MAS will be difficult to deploy. Progeny testing and the use of pedigree in the analysis can provide effective identification of the superior genetic factors that underpin these complex traits. Recently, it has been shown that estimated breeding values (EBVs) can be developed for complex potato traits. Using a combination of MAS and EBVs for simple and complex traits can lead to a significant reduction in the length of the breeding cycle for the identification of superior germplasm.

Prediction-based association control scheme in dense femtocell networks.

PubMed

Sung, Nak Woon; Pham, Ngoc-Thai; Huynh, Thong; Hwang, Won-Joo; You, Ilsun; Choo, Kim-Kwang Raymond

2017-01-01

The deployment of large number of femtocell base stations allows us to extend the coverage and efficiently utilize resources in a low cost manner. However, the small cell size of femtocell networks can result in frequent handovers to the mobile user, and consequently throughput degradation. Thus, in this paper, we propose predictive association control schemes to improve the system's effective throughput. Our design focuses on reducing handover frequency without impacting on throughput. The proposed schemes determine handover decisions that contribute most to the network throughput and are proper for distributed implementations. The simulation results show significant gains compared with existing methods in terms of handover frequency and network throughput perspective.

Segmented amplifier configurations for laser amplifier

DOEpatents

Hagen, Wilhelm F.

1979-01-01

An amplifier system for high power lasers, the system comprising a compact array of segments which (1) preserves high, large signal gain with improved pumping efficiency and (2) allows the total amplifier length to be shortened by as much as one order of magnitude. The system uses a three dimensional array of segments, with the plane of each segment being oriented at substantially the amplifier medium Brewster angle relative to the incident laser beam and with one or more linear arrays of flashlamps positioned between adjacent rows of amplifier segments, with the plane of the linear array of flashlamps being substantially parallel to the beam propagation direction.

The demand for physician services. Evidence from a natural experiment.

PubMed

Cockx, Bart; Brasseur, Carine

2003-11-01

This study exploits a natural experiment in Belgium to estimate the effect of copayment increases on the demand for physician services. It shows how a differences-in-differences (DD) estimator of the price effects can be decomposed into effects induced by the common average proportional price increase (income effects) and by the change in relative prices (substitution effects). The price elasticity of a uniform proportional price increase is relatively small (-0.13 for men and -0.03 for women). Substitution effects are large, especially for women, but imprecisely estimated. Despite the substantial price increases, the efficiency gain of the reform, if any, is modest.

Large photorefractive effect in a thermally decomposed polymer compared with that in molecularly doped systems

NASA Astrophysics Data System (ADS)

Yokoyama, Kenji; Arishima, Koichi; Sukegawa, Ken

1994-07-01

Photorefractive polymers with the same electro-optic effect were fabricated to investigate the photorefractive effects in different photoconductive systems. The photoconduction in the polymers was varied by the addition of squarylium dye to diethylaminobenzaldehyde-diphenylhydrazone (DEH), by the formation of a charge-transfer complex between tetracyanoquinodimethane and DEH, and by the thermal decomposition of DEH. The largest photorefractive effect was observed in the thermally decomposed polymer among these polymers. A diffraction efficiency of 1.1% and a beam-coupling gain coefficient of 10 cm-1 were achieved in a 34.9 V/μm dc electric field.

Multi-stage decoding of multi-level modulation codes

NASA Technical Reports Server (NTRS)

Lin, Shu; Kasami, Tadao; Costello, Daniel J., Jr.

1991-01-01

Various types of multi-stage decoding for multi-level modulation codes are investigated. It is shown that if the component codes of a multi-level modulation code and types of decoding at various stages are chosen properly, high spectral efficiency and large coding gain can be achieved with reduced decoding complexity. Particularly, it is shown that the difference in performance between the suboptimum multi-stage soft-decision maximum likelihood decoding of a modulation code and the single-stage optimum soft-decision decoding of the code is very small, only a fraction of dB loss in signal to noise ratio at a bit error rate (BER) of 10(exp -6).

Strategies for Energy Efficient Resource Management of Hybrid Programming Models

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

Li, Dong; Supinski, Bronis de; Schulz, Martin

2013-01-01

Many scientific applications are programmed using hybrid programming models that use both message-passing and shared-memory, due to the increasing prevalence of large-scale systems with multicore, multisocket nodes. Previous work has shown that energy efficiency can be improved using software-controlled execution schemes that consider both the programming model and the power-aware execution capabilities of the system. However, such approaches have focused on identifying optimal resource utilization for one programming model, either shared-memory or message-passing, in isolation. The potential solution space, thus the challenge, increases substantially when optimizing hybrid models since the possible resource configurations increase exponentially. Nonetheless, with the accelerating adoptionmore » of hybrid programming models, we increasingly need improved energy efficiency in hybrid parallel applications on large-scale systems. In this work, we present new software-controlled execution schemes that consider the effects of dynamic concurrency throttling (DCT) and dynamic voltage and frequency scaling (DVFS) in the context of hybrid programming models. Specifically, we present predictive models and novel algorithms based on statistical analysis that anticipate application power and time requirements under different concurrency and frequency configurations. We apply our models and methods to the NPB MZ benchmarks and selected applications from the ASC Sequoia codes. Overall, we achieve substantial energy savings (8.74% on average and up to 13.8%) with some performance gain (up to 7.5%) or negligible performance loss.« less

Fast Component Pursuit for Large-Scale Inverse Covariance Estimation.

PubMed

Han, Lei; Zhang, Yu; Zhang, Tong

2016-08-01

The maximum likelihood estimation (MLE) for the Gaussian graphical model, which is also known as the inverse covariance estimation problem, has gained increasing interest recently. Most existing works assume that inverse covariance estimators contain sparse structure and then construct models with the ℓ 1 regularization. In this paper, different from existing works, we study the inverse covariance estimation problem from another perspective by efficiently modeling the low-rank structure in the inverse covariance, which is assumed to be a combination of a low-rank part and a diagonal matrix. One motivation for this assumption is that the low-rank structure is common in many applications including the climate and financial analysis, and another one is that such assumption can reduce the computational complexity when computing its inverse. Specifically, we propose an efficient COmponent Pursuit (COP) method to obtain the low-rank part, where each component can be sparse. For optimization, the COP method greedily learns a rank-one component in each iteration by maximizing the log-likelihood. Moreover, the COP algorithm enjoys several appealing properties including the existence of an efficient solution in each iteration and the theoretical guarantee on the convergence of this greedy approach. Experiments on large-scale synthetic and real-world datasets including thousands of millions variables show that the COP method is faster than the state-of-the-art techniques for the inverse covariance estimation problem when achieving comparable log-likelihood on test data.

Modeling and studying of white light emitting diodes based on CdS/ZnS spherical quantum dots

NASA Astrophysics Data System (ADS)

Hasanirokh, K.; Asgari, A.

2018-07-01

In this paper, we propose a quantum dot (QD) based white light emitting diode (WLED) structure to study theoretically the material gain and quantum efficiency of the system. We consider the spherical QDs with a II-VI semiconductor core (CdS) that covered with a wider band gap semiconductor acting as a shell (ZnS). In order to generate white light spectrum, we use layers with different dot size that can emit blue, green and red colors. The blue emission originating from CdS core combines to green/orange components originating from ZnS shell and creates an efficiency white light emission. To model this device, at first, we solve Schrödinger and Poisson equations self consistently and obtain eigen energies and wave functions. Then, we calculate the optical gain and internal quantum efficiency (IQE) of a CdS/ZnS LED sample. We investigate the structural parameter effects on the optical properties of the WLED. The numerical results show that the gain profile and IQE curves depend strongly on the structural parameters such as dot size, carrier density and volume scaling parameter. The gain profile becomes higher and wider with increasing the core radius while it becomes less and narrower with increasing the shell thickness. Furthermore, it is found that the volume scaling parameter can manage the system quantum efficiency.

Methionine+cystine requirement of broiler chickens fed low-density diets under tropical conditions.

PubMed

Aftab, Usama; Ashraf, Muhammad

2009-03-01

Two experiments were conducted to determine the M+C requirement of straight-run broiler chickens (Hubbard x Hubbard) during the period 4-21 (Exp. 1) and 21-40 (Exp. 2) days of age. Experiments were conducted during summer months (July-August) in open-sided houses, thus exposing chicks to chronic heat stress. Daily min-max temperature averaged 26-37C (Exp. 1) and 23-36C (Exp. 2). M+C deficient basal diets were formulated to contain low-nutrient-density, i.e., 2750 kcal per kg ME, 20.1% CP (Exp. 1), and 2780 kcal per kg ME, 17.0% CP (Exp. 2). Diets were supplemented with DL-methionine to provide total M+C level ranging from 0.64 to 0.89 % (six increments) and 0.54 to 0.79% (six increments), respectively in experiment 1 and 2. Requirements (0.95 of the maximum quadratic response) were found to be 0.77 and 0.75% total M+C, respectively for gain and feed efficiency, during 4-21 days; and 0.67% total M+C for both gain and feed efficiency during 21-40 days of age. Calculated on the digestible M+C basis, the estimates were 0.67 and 0.65% respectively for gain and feed efficiency during 4-21 days of age; and 0.60% for gain and feed efficiency during 21-40 days of age.

A review of feed efficiency in swine: biology and application.

PubMed

Patience, John F; Rossoni-Serão, Mariana C; Gutiérrez, Néstor A

2015-01-01

Feed efficiency represents the cumulative efficiency with which the pig utilizes dietary nutrients for maintenance, lean gain and lipid accretion. It is closely linked with energy metabolism, as the oxidation of carbon-containing components in the feed drive all metabolic processes. While much is known about nutrient utilization and tissue metabolism, blending these subjects into a discussion on feed efficiency has proven to be difficult. For example, while increasing dietary energy concentration will almost certainly increase feed efficiency, the correlation between dietary energy concentration and feed efficiency is surprisingly low. This is likely due to the plethora of non-dietary factors that impact feed efficiency, such as the environment and health as well as individual variation in maintenance requirements, body composition and body weight. Nonetheless, a deeper understanding of feed efficiency is critical at many levels. To individual farms, it impacts profitability. To the pork industry, it represents its competitive position against other protein sources. To food economists, it means less demand on global feed resources. There are environmental and other societal implications as well. Interestingly, feed efficiency is not always reported simply as a ratio of body weight gain to feed consumed. This review will explain why this arithmetic calculation, as simple as it initially seems, and as universally applied as it is in science and commerce, can often be misleading due to errors inherent in recording of both weight gain and feed intake. This review discusses the importance of feed efficiency, the manner in which it can be measured and reported, its basis in biology and approaches to its improvement. It concludes with a summary of findings and recommendations for future efforts.

Influence of dissolved organic matter concentration and composition on the removal efficiency of perfluoroalkyl substances (PFASs) during drinking water treatment.

PubMed

Kothawala, Dolly N; Köhler, Stephan J; Östlund, Anna; Wiberg, Karin; Ahrens, Lutz

2017-09-15

Drinking water treatment plants (DWTPs) are constantly adapting to a host of emerging threats including the removal of micro-pollutants like perfluoroalkyl substances (PFASs), while concurrently considering how background levels of dissolved organic matter (DOM) influences their removal efficiency. Two adsorbents, namely anion exchange (AE) and granulated active carbon (GAC) have shown particular promise for PFAS removal, yet the influence of background levels of DOM remains poorly explored. Here we considered how the removal efficiency of 13 PFASs are influenced by two contrasting types of DOM at four concentrations, using both AE (Purolite A-600 ® ) and GAC (Filtrasorb 400 ® ). We placed emphasis on the pre-equilibrium conditions to gain better mechanistic insight into the dynamics between DOM, PFASs and adsorbents. We found AE to be very effective at removing both PFASs and DOM, while largely remaining resistant to even high levels of background DOM (8 mg carbon L -1 ) and surprisingly found that smaller PFASs were removed slightly more efficiently than longer chained counterparts, In contrast, PFAS removal efficiency with GAC was highly variable with PFAS chain length, often improving in the presence of DOM, but with variable response based on the type of DOM and PFAS chain length. Copyright © 2017 Elsevier Ltd. All rights reserved.

High efficiency fourth-harmonic generation from nanosecond fiber master oscillator power amplifier

NASA Astrophysics Data System (ADS)

Mu, Xiaodong; Steinvurzel, Paul; Rose, Todd S.; Lotshaw, William T.; Beck, Steven M.; Clemmons, James H.

2016-03-01

We demonstrate high power, deep ultraviolet (DUV) conversion to 266 nm through frequency quadrupling of a nanosecond pulse width 1064 nm fiber master oscillator power amplifier (MOPA). The MOPA system uses an Yb-doped double-clad polarization-maintaining large mode area tapered fiber as the final gain stage to generate 0.5-mJ, 10 W, 1.7- ns single mode pulses at a repetition rate of 20 kHz with measured spectral bandwidth of 10.6 GHz (40 pm), and beam qualities of Mx 2=1.07 and My 2=1.03, respectively. Using LBO and BBO crystals for the second-harmonic generation (SHG) and fourth-harmonic generation (FHG), we have achieved 375 μJ (7.5 W) and 92.5 μJ (1.85 W) at wavelengths of 532 nm and 266 nm, respectively. To the best of our knowledge these are the highest narrowband infrared, green and UV pulse energies obtained to date from a fully spliced fiber amplifier. We also demonstrate high efficiency SHG and FHG with walk-off compensated (WOC) crystal pairs and tightly focused pump beam. An SHG efficiency of 75%, FHG efficiency of 47%, and an overall efficiency of 35% from 1064 nm to 266 nm are obtained.

Doped-channel heterojunction structures for millimeter-wave discrete devices and MMICs

NASA Technical Reports Server (NTRS)

Saunier, P.; Kao, Y. C.; Khatibzadeh, A. M.; Tserng, H. Q.; Bradshaw, K.

1989-01-01

AlGaAs/InGaAs/GaAs-type heterostructures with one or two channels have been used to fabricate both discrete devices and monolithic amplifiers for millimeter-wave operation. The authors report that 0.25-micron x 50-micron discrete devices delivered a power density of 1 W/mm with 2.9-dB gain and 25 percent efficiency at 60 GHz. A 100-micron monolithic single-stage amplifier demonstrated a record 40 percent efficiency at 32 GHz, and a two-stage monolithic amplifier achieved a record 31.3 percent efficiency with 72-mW power and 13-dB gain at 32 GHz.

Oil-free transportation

NASA Astrophysics Data System (ADS)

Lovins, Amory B.

2015-03-01

Automotive efficiency can be cost-effectively improved ˜2-3× by integrated reductions in mass, drag, and rolling resistance. (Mass is the key because it causes two-thirds of tractive load.) These improvements make affordable a variety of electrified advanced powertrain options that can raise efficiency by a further ˜2×, achieving ˜1-2 L-gasoline-equivalent per 100 km. These innovations are starting to enter the market. They could spread more by competition than by regulation. So will 3× gains in truck and 3-6× gains in airplane efficiency. Such superefficient vehicles can profitably eliminate oil use and decouple mobility from climate change and pollution.

Effect of structure variation of the aptamer-DNA duplex probe on the performance of displacement-based electrochemical aptamer sensors.

PubMed

Pang, Jie; Zhang, Ziping; Jin, Haizhu

2016-03-15

Electrochemical aptamer-based (E-AB) sensors employing electrode-immobilized, redox-tagged aptamer probes have emerged as a promising platform for the sensitive and quick detection of target analytes ranging from small molecules to proteins. Signal generation in this class of sensor is linked to change in electron transfer efficiency upon binding-induced change in flexibility/conformation of the aptamer probe. Because of this signaling mechanism, signal gains of these sensors can be improved by employing a displacement-based recognition system, which links target binding with a large-scale flexibility/conformation shift from the aptamer-DNA duplex to the single-stranded DNA or the native aptamer. Despite the relatively large number of displacement-based E-AB sensor samples, little attention has been paid to the structure variation of the aptamer-DNA duplex probe. Here we detail the effects of complementary length and position of the aptamer-DNA duplex probe on the performance of a model displacement-based E-AB sensor for ATP. We find that, greater background suppression and signal gain are observed with longer complementary length of the aptamer-DNA duplex probe. However, sensor equilibration time slows monotonically with increasing complementary length; and with too many target binding sites in aptamer sequence being occupied by the complementary DNA, the aptamer-target binding does not occur and no signal gain observed. We also demonstrate that signal gain of the displacement-based E-AB sensor is strongly dependent on the complementary position of the aptamer-DNA duplex probe, with complementary position located at the electrode-attached or redox-tagged end of the duplex probe, larger background suppression and signal increase than that of the middle position are observed. These results highlight the importance of rational structure design of the aptamer-DNA duplex probe and provide new insights into the optimization of displacement-based E-AB sensors. Copyright © 2015 Elsevier B.V. All rights reserved.

Ultra-high gain diffusion-driven organic transistor.

PubMed

Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

2016-02-01

Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal-semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics.

Ultra-high gain diffusion-driven organic transistor

NASA Astrophysics Data System (ADS)

Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

2016-02-01

Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal-semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics.

A Method for Large Eddy Simulation of Acoustic Combustion Instabilities

NASA Astrophysics Data System (ADS)

Wall, Clifton; Pierce, Charles; Moin, Parviz

2002-11-01

A method for performing Large Eddy Simulation of acoustic combustion instabilities is presented. By extending the low Mach number pressure correction method to the case of compressible flow, a numerical method is developed in which the Poisson equation for pressure is replaced by a Helmholtz equation. The method avoids the acoustic CFL condition by using implicit time advancement, leading to large efficiency gains at low Mach number. The method also avoids artificial damping of acoustic waves. The numerical method is attractive for the simulation of acoustic combustion instabilities, since these flows are typically at low Mach number, and the acoustic frequencies of interest are usually low. Both of these characteristics suggest the use of larger time steps than those allowed by an acoustic CFL condition. The turbulent combustion model used is the Combined Conserved Scalar/Level Set Flamelet model of Duchamp de Lageneste and Pitsch for partially premixed combustion. Comparison of LES results to the experiments of Besson et al will be presented.

Large Thermal Motion in Halide Perovskites

DOE PAGES

Tyson, T. A.; Gao, W.; Chen, Y. -S.; ...

2017-08-24

Solar cells based on hybrid perovskites have shown high efficiency while possessing simple processing methods. To gain a fundamental understanding of their properties on an atomic level, we investigate single crystals of CH 3NH 3PbI 3 with a narrow transition (~5 K) near 327 K. Temperature dependent structural measurements reveal a persistent tetragonal structure with smooth changes in the atomic displacement parameters (ADPs) on crossing T*. We show that the ADPs for I ions yield extended flat regions in the potential wells consistent with the measured large thermal expansion parameter. Molecular dynamics simulations reveal that this material exhibits significant asymmetriesmore » in the Pb-I pair distribution functions. We also show that the intrinsically enhanced freedom of motion of the iodine atoms enables large deformations. This flexibility (softness) of the atomic structure results in highly localized atomic relaxation about defects and hence accounts for both the high carrier mobility as well as the structural instability.« less

Efficient processing of fluorescence images using directional multiscale representations.

PubMed

Labate, D; Laezza, F; Negi, P; Ozcan, B; Papadakis, M

2014-01-01

Recent advances in high-resolution fluorescence microscopy have enabled the systematic study of morphological changes in large populations of cells induced by chemical and genetic perturbations, facilitating the discovery of signaling pathways underlying diseases and the development of new pharmacological treatments. In these studies, though, due to the complexity of the data, quantification and analysis of morphological features are for the vast majority handled manually, slowing significantly data processing and limiting often the information gained to a descriptive level. Thus, there is an urgent need for developing highly efficient automated analysis and processing tools for fluorescent images. In this paper, we present the application of a method based on the shearlet representation for confocal image analysis of neurons. The shearlet representation is a newly emerged method designed to combine multiscale data analysis with superior directional sensitivity, making this approach particularly effective for the representation of objects defined over a wide range of scales and with highly anisotropic features. Here, we apply the shearlet representation to problems of soma detection of neurons in culture and extraction of geometrical features of neuronal processes in brain tissue, and propose it as a new framework for large-scale fluorescent image analysis of biomedical data.

Efficient green lasers for high-resolution scanning micro-projector displays

NASA Astrophysics Data System (ADS)

Bhatia, Vikram; Bauco, Anthony S.; Oubei, Hassan M.; Loeber, David A. S.

2010-02-01

Laser-based projectors are gaining increased acceptance in mobile device market due to their low power consumption, superior image quality and small size. The basic configuration of such micro-projectors is a miniature mirror that creates an image by raster scanning the collinear red, blue and green laser beams that are individually modulated on a pixel-bypixel basis. The image resolution of these displays can be limited by the modulation bandwidth of the laser sources, and the modulation speed of the green laser has been one of the key limitations in the development of these displays. We will discuss how this limitation is fundamental to the architecture of many laser designs and then present a green laser configuration which overcomes these difficulties. In this green laser architecture infra-red light from a distributed Bragg-reflector (DBR) laser diode undergoes conversion to green light in a waveguided second harmonic generator (SHG) crystal. The direct doubling in a single pass through the SHG crystal allows the device to operate at the large modulation bandwidth of the DBR laser. We demonstrate that the resultant product has a small footprint (<0.7 cc envelope volume), high efficiency (>9% electrical-to-optical conversion) and large modulation bandwidth (>100 MHz).

Summary and recent results from the NASA advanced High Speed Propeller Research Program

NASA Technical Reports Server (NTRS)

Mitchell, G. A.; Mikkelson, D. C.

1982-01-01

Advanced high-speed propellers offer large performance improvements for aircraft that cruise in the Mach 0.7 to 0.8 speed regime. The current status of the NASA research program on high-speed propeller aerodynamics, acoustics, and aeroelastics is described. Recent wind tunnel results for five 8- to 10-blade advanced models are compared with analytical predictions. Test results show that blade sweep was important in achieving net efficiencies near 80 percent at Mach 0.8 and reducing near-field cruise noise by dB. Lifting line and lifting surface aerodynamic analysis codes are under development and some initial lifting line results are compared with propeller force and probe data. Some initial laser velocimeter measurements of the flow field velocities of an 8-bladed 45 deg swept propeller are shown. Experimental aeroelastic results indicate that cascade effects and blade sweep strongly affect propeller aeroelastic characteristics. Comparisons of propeller near-field noise data with linear acoustic theory indicate that the theory adequate predicts near-field noise for subsonic tip speeds but overpredicts the noise for supersonic tip speeds. Potential large gains in propeller efficiency of 7 to 11 percent at Mach 0.8 may be possible with advanced counter-rotation propellers.

Efficient processing of fluorescence images using directional multiscale representations

PubMed Central

Labate, D.; Laezza, F.; Negi, P.; Ozcan, B.; Papadakis, M.

2017-01-01

Recent advances in high-resolution fluorescence microscopy have enabled the systematic study of morphological changes in large populations of cells induced by chemical and genetic perturbations, facilitating the discovery of signaling pathways underlying diseases and the development of new pharmacological treatments. In these studies, though, due to the complexity of the data, quantification and analysis of morphological features are for the vast majority handled manually, slowing significantly data processing and limiting often the information gained to a descriptive level. Thus, there is an urgent need for developing highly efficient automated analysis and processing tools for fluorescent images. In this paper, we present the application of a method based on the shearlet representation for confocal image analysis of neurons. The shearlet representation is a newly emerged method designed to combine multiscale data analysis with superior directional sensitivity, making this approach particularly effective for the representation of objects defined over a wide range of scales and with highly anisotropic features. Here, we apply the shearlet representation to problems of soma detection of neurons in culture and extraction of geometrical features of neuronal processes in brain tissue, and propose it as a new framework for large-scale fluorescent image analysis of biomedical data. PMID:28804225

Rapid Maturation of Edge Sensor Technology and Potential Application in Large Space Telescopes with Segmented Primary Mirrors

NASA Technical Reports Server (NTRS)

Montgomery, Edward E., IV; Smith, W. Scott (Technical Monitor)

2002-01-01

This paper explores the history and results of the last two year's efforts to transition inductive edge sensor technology from Technology Readiness Level 2 to Technology Readiness Level 6. Both technical and programmatic challenges were overcome in the design, fabrication, test, and installation of over a thousand sensors making up the Segment Alignment Maintenance System (SAMs) for the 91 segment, 9.2-meter. Hobby Eberly Telescope (HET). The integration of these sensors with the control system will be discussed along with serendipitous leverage they provided for both initialization alignment and operational maintenance. The experience gained important insights into the fundamental motion mechanics of large segmented mirrors, the relative importance of the variance sources of misalignment errors, the efficient conduct of a program to mature the technology to the higher levels. Unanticipated factors required the team to develop new implementation strategies for the edge sensor information which enabled major segmented mirror controller design simplifications. The resulting increase in the science efficiency of HET will be shown. Finally, the on-going effort to complete the maturation of inductive edge sensor by delivering space qualified versions for future IR (infrared radiation) space telescopes.

Perspectives on weight gain and lifestyle practices during pregnancy among women with a history of macrosomia: a qualitative study in the Republic of Ireland

PubMed Central

2013-01-01

Background Excessive weight gain during pregnancy is a major risk factor for macrosomia (high birth weight delivery). This study aimed to explore views about weight gain and lifestyle practices during pregnancy among women with a history of macrosomia. Methods A qualitative descriptive study was conducted. Twenty-one second-time mothers whose first infant was macrosomic (>4 kg) were recruited from a randomised trial in a large maternity hospital in the Republic of Ireland. Semi-structured interviews were conducted with participants at both 6 and 12 months after their second pregnancy. Inductive thematic analysis was used to identify distinct themes. Results The mothers believed in following their prenatal food cravings to meet their baby’s needs, but this led some to eat excessively. Many of the women cut back heavily on physical activity during pregnancy due to perceived risks to the baby. Physical conditions and discomforts during pregnancy often limited maternal control over weight and lifestyle practices. The women were not particularly concerned about weight gain during pregnancy and most did not favour the notion of introducing weight gain guidelines into routine antenatal care. Common differences perceived by the women between their first and second pregnancy included: increased concern about weight gain in their second pregnancy due to prior difficulties with postpartum weight loss and increased time demands in their second pregnancy impeded healthy lifestyle practices. Most women did not alter their perspectives on weight gain and lifestyle practices in their second pregnancy in response to having a macrosomic infant in their first pregnancy. Conclusions This analysis exposed numerous barriers to healthy pregnancy weight gain. The findings suggest that women may need to be advised to follow their prenatal food cravings in moderation. Pregnant women with children already may benefit from education on time-efficient methods of integrating healthy eating practices and physical activity into their lifestyles. Women with a history of macrosomia may need information about the importance of avoiding high weight gain in subsequent pregnancies. PMID:24195741

Highly efficient multifunctional metasurface for high-gain lens antenna application

NASA Astrophysics Data System (ADS)

Hou, Haisheng; Wang, Guangming; Li, Haipeng; Guo, Wenlong; Li, Tangjing

2017-07-01

In this paper, a novel multifunctional metasurface combining linear-to-circular polarization conversion and electromagnetic waves focusing has been proposed and applied to design a high-gain lens antenna working at Ku band. The multifunctional metasurface consists of 15 × 15 unit cells. Each unit cell is composed of four identical metallic layers and three intermediate dielectric layers. Due to well optimization, the multifunctional metasurface can convert the linearly polarized waves generated by the source to circularly polarized waves and focus the waves. By placing a patch antenna operating at 15 GHz at the focal point of the metasurface and setting the focal distance to diameter ratio ( F/ D) to 0.34, we obtain a multifunctional lens antenna. Simulated and measured results coincide well, indicating that the metasurface can convert linearly polarized waves to right-handed circularly polarized waves at 15 GHz with excellent performances in terms of the 3 dB axial ratio bandwidth of 5.3%, realized gain of 16.9 dB and aperture efficiency of 41.2%. Because of the advantages of high gain, competitive efficiency and easy fabrication, the proposed lens antenna has a great potential application in wireless and satellite communication.

MMIC DHBT Common-Base Amplifier for 172 GHz

NASA Technical Reports Server (NTRS)

Paidi, Vamsi; Griffith, Zack; Wei, Yun; Dahlstrom, Mttias; Urteaga, Miguel; Rodwell, Mark; Samoska, Lorene; Fung, King Man; Schlecht, Erich

2006-01-01

Figure 1 shows a single-stage monolithic microwave integrated circuit (MMIC) power amplifier in which the gain element is a double-heterojunction bipolar transistor (DHBT) connected in common-base configuration. This amplifier, which has been demonstrated to function well at a frequency of 172 GHz, is part of a continuing effort to develop compact, efficient amplifiers for scientific instrumentation, wide-band communication systems, and radar systems that will operate at frequencies up to and beyond 180 GHz. The transistor is fabricated from a layered structure formed by molecular beam epitaxy in the InP/InGaAs material system. A highly doped InGaAs base layer and a collector layer are fabricated from the layered structure in a triple mesa process. The transistor includes two separate emitter fingers, each having dimensions of 0.8 by 12 m. The common-base configuration was chosen for its high maximum stable gain in the frequency band of interest. The input-matching network is designed for high bandwidth. The output of the transistor is matched to a load line for maximum saturated output power under large-signal conditions, rather than being matched for maximum gain under small-signal conditions. In a test at a frequency of 172 GHz, the amplifier was found to generate an output power of 7.5 mW, with approximately 5 dB of large-signal gain (see Figure 2). Moreover, the amplifier exhibited a peak small-signal gain of 7 dB at a frequency of 176 GHz. This performance of this MMIC single-stage amplifier containing only a single transistor represents a significant advance in the state of the art, in that it rivals the 170-GHz performance of a prior MMIC three-stage, four-transistor amplifier. [The prior amplifier was reported in "MMIC HEMT Power Amplifier for 140 to 170 GHz" (NPO-30127), NASA Tech Briefs, Vol. 27, No. 11 (November 2003), page 49.] This amplifier is the first heterojunction- bipolar-transistor (HBT) amplifier built for medium power operation in this frequency band. The performance of the amplifier as measured in the aforementioned tests suggests that InP/InGaAs HBTs may be superior to high-electron-mobility (HEMT) transistors in that the HBTs may offer more gain per stage and more output power per transistor.

Isolation and characterization of Bacillus subtilis CH16 strain from chicken gastrointestinal tracts for use as a feed supplement to promote weight gain in broilers.

PubMed

Nguyen, A T V; Nguyen, D V; Tran, M T; Nguyen, L T; Nguyen, A H; Phan, T-N

2015-06-01

Spore-forming bacterial strains were isolated from chicken gastrointestinal tracts to develop a heat-stable feed supplement that promotes weight gain in broilers. Seven Bacillus strains having more than 90% sporulation were screened from the isolates and identified to be closely related with Bacillus subtilis and Bacillus licheniformis. Of the seven strains, B. subtilis CH16 was selected to develop a feed supplement for broilers, because it formed 100% heat-stable spores, grew rapidly at 42°C and quickly formed a biofilm. In large-scale trials in broilers (n ≥ 1150 per group), the group fed CH16 (3 × 10(6) CFU g(-1) pellet) showed higher average daily gain (ADG = 61·16) and lower food conversion ratio (FCR = 1·696) than did the group fed B. licheniformis CH22 (ADG = 57·10 and FCR = 1·792), the group fed B. subtilis HU58 (ADG = 51·90 and FCR = 1·868), BioPlus group (ADG = 59·32 and FCR = 1·807) and the control group (ADG = 56·02 and FCR = 1·880). In conclusion, CH16 spores significantly increased ADG by 9·17% and reduced FCR by 9·79% in broilers. The result supports the use of B. subtilis CH16 of chicken intestinal origin as a feed supplement that promote weight gain in broilers. Significance and impact of the study: This study reports screening of Bacillus strains isolated from chicken gastrointestinal tracts for development of a feed supplement that promote weight gain in broilers. Of the seven Bacillus isolates with high sporulation efficiency (≥90%), Bacillus subtilis CH16 strain showed the best growth and biofilm formation at body temperature of broilers (42°C). In large-scale trials in broilers (n ≥ 1150 per group), CH16 spores induced a 9·17% increase in daily weight gain (ADG) and a 9·79% reduction in FCR while the commercial BioPlus(®) YC induced only a 5·89% increase in ADG and a 3·88% reduction in FCR. © 2015 The Society for Applied Microbiology.

Multi-channel programmable power supply with temperature compensation for silicon sensors

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

Shukla, R. A.; Achanta, V. G.; Dugad, S. R., E-mail: dugad@cern.ch

Silicon Photo-Multipliers (SiPMs) are increasingly becoming popular for discrete photon counting applications due to the wealth of advantages they offer over conventional photo-detectors such as photo-multiplier tubes and hybrid photo-diodes. SiPMs are used in variety of applications ranging from high energy physics and nuclear physics experiments to medical diagnostics. The gain of a SiPM is directly proportional to the difference between applied and breakdown voltage of the device. However, the breakdown voltage depends critically on the ambient temperature and has a large temperature co-efficient in the range of 40-60 mV/°C resulting in a typical gain variation of 3%-5%/°C [Dinu etmore » al., in IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE, 2010), p. 215]. We plan to use the SiPM as a replacement for PMT in the cosmic ray experiment (GRAPES-3) at Ooty [Gupta et al., Nucl. Instrum. Methods Phys. Res., Sect. A 540, 311 (2005)]. There the SiPMs will be operated in an outdoor environment subjected to temperature variation of about 15 °C over a day. A gain variation of more than 50% was observed for such large variations in the temperature. To stabilize the gain of the SiPM under such operating conditions, a low-cost, multi-channel programmable power supply (0-90 V) was designed that simultaneously provides the bias voltage to 16 SiPMs. The programmable power supply (PPS) was designed to automatically adjust the operating voltage for each channel with a built-in closed loop temperature feedback mechanism. The PPS provides bias voltage with a precision of 6 mV and measures the load current with a precision of 1 nA. Using this PPS, a gain stability of 0.5% for SiPM (Hamamatsu, S10931-050P) has been demonstrated over a wide temperature range of 15 °C. The design methodology of the PPS system, its validation, and the results of the tests carried out on the SiPM is presented in this article. The proposed design also has the capability of gain stabilization of devices with non-linear thermal response.« less

Grating enhanced solid-state laser amplifiers

DOEpatents

Erlandson, Alvin C.; Britten, Jerald A.

2010-11-09

A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. Such an invention, as disclosed herein, uses diffraction gratings to increase gain, stored energy density, and pumping efficiency of solid-state laser gain media, such as, but not limited to rods, disks and slabs. By coupling predetermined gratings to solid-state gain media, such as crystal or ceramic laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

PubMed

Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

2010-06-15

We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

All fiber passively Q-switched laser

DOEpatents

Soh, Daniel B. S.; Bisson, Scott E

2015-05-12

Embodiments relate to an all fiber passively Q-switched laser. The laser includes a large core doped gain fiber having a first end. The large core doped gain fiber has a first core diameter. The laser includes a doped single mode fiber (saturable absorber) having a second core diameter that is smaller than the first core diameter. The laser includes a mode transformer positioned between a second end of the large core doped gain fiber and a first end of the single mode fiber. The mode transformer has a core diameter that transitions from the first core diameter to the second core diameter and filters out light modes not supported by the doped single mode fiber. The laser includes a laser cavity formed between a first reflector positioned adjacent the large core doped gain fiber and a second reflector positioned adjacent the doped single mode fiber.

Sugar assimilation and digestive efficiency in Wahlberg's epauletted fruit bat (Epomophorus wahlbergi).

PubMed

Downs, Colleen T; Mqokeli, Babalwa; Singh, Preshnee

2012-03-01

Fruit- and nectar-feeding bats have high energy demands because of the cost of flight, and sugar is a good fuel because it is easily digested and absorbed. This study investigated the digestive efficiency of different sugars at different concentrations in Wahlberg's epauletted fruit bat (Epomophorus wahlbergi). We predicted that the sugar type and concentration would affect the total amount of solution consumed, while the total energy gained and the apparent assimilation efficiency would be high, irrespective of sugar type or concentration. Equicaloric solutions of two sugar types, glucose and sucrose, at low (10%), medium (15%) and high (25%) concentrations were offered in separate trials to bats. Total amount of solution consumed, total energy gained from each solution, and apparent assimilation efficiency, were measured. Bats had higher total volumetric intake of glucose and sucrose at the low concentrations than at the higher concentrations. However, bats maintained similar total energy intake on the respective glucose and sucrose concentrations. Bats were found to have high assimilation efficiencies on both glucose and sucrose irrespective of concentration. As bats used both sugars efficiently to maximize and maintain energy gain, it is expected that they feed opportunistically on fruit in the wild depending on temporal and spatial availability to obtain their energy requirements. Furthermore, fruit with high sucrose or glucose content will be consumed. Copyright © 2011 Elsevier Inc. All rights reserved.

A Combined Eulerian-Lagrangian Data Representation for Large-Scale Applications.

PubMed

Sauer, Franz; Xie, Jinrong; Ma, Kwan-Liu

2017-10-01

The Eulerian and Lagrangian reference frames each provide a unique perspective when studying and visualizing results from scientific systems. As a result, many large-scale simulations produce data in both formats, and analysis tasks that simultaneously utilize information from both representations are becoming increasingly popular. However, due to their fundamentally different nature, drawing correlations between these data formats is a computationally difficult task, especially in a large-scale setting. In this work, we present a new data representation which combines both reference frames into a joint Eulerian-Lagrangian format. By reorganizing Lagrangian information according to the Eulerian simulation grid into a "unit cell" based approach, we can provide an efficient out-of-core means of sampling, querying, and operating with both representations simultaneously. We also extend this design to generate multi-resolution subsets of the full data to suit the viewer's needs and provide a fast flow-aware trajectory construction scheme. We demonstrate the effectiveness of our method using three large-scale real world scientific datasets and provide insight into the types of performance gains that can be achieved.

Novel design of inherently gain-flattened discrete highly nonlinear photonic crystal fiber Raman amplifier and dispersion compensation using a single pump in C-band.

PubMed

Varshney, Shailendra; Fujisawa, Takeshi; Saitoh, Kunimasa; Koshiba, Masanori

2005-11-14

In this paper, we report, for the first time, an inherently gain-flattened discrete highly nonlinear photonic crystal fiber (HNPCF) Raman amplifier (HNPCF-RA) design which shows 13.7 dB of net gain (with +/-0.85-dB gain ripple) over 28-nm bandwidth. The wavelength dependent leakage loss property of HNPCF is used to flatten the Raman gain of the amplifier module. The PCF structural design is based on W-shaped refractive index profile where the fiber parameters are well optimized by homely developed genetic algorithm optimization tool integrated with an efficient vectorial finite element method (V-FEM). The proposed fiber design has a high Raman gain efficiency of 4.88 W(-1) . km(-1) at a frequency shift of 13.1 THz, which is precisely evaluated through V-FEM. Additionally, the designed module, which shows ultra-wide single mode operation, has a slowly varying negative dispersion coefficient (-107.5 ps/nm/km at 1550 nm) over the operating range of wavelengths. Therefore, our proposed HNPCF-RA module acts as a composite amplifier with dispersion compensator functionality in a single component using a single pump.

Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

PubMed Central

Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

2016-01-01

With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

Roadmap of retail electricity market reform in China: assisting in mitigating wind energy curtailment

NASA Astrophysics Data System (ADS)

Yu, Dezhao; Qiu, Huadong; Yuan, Xiang; Li, Yuan; Shao, Changzheng; Lin, You; Ding, Yi

2017-01-01

Among the renewable energies, wind energy has gained the rapidest development in China. Moreover wind power generation has been penetrated into power system in a large scale. However, the high level wind curtailment also indicates a low efficiency of wind energy utilization over the last decade in China. One of the primary constraints on the utilization of wind energy is the lack of an electricity market, in which renewable energies can compete equally with traditional fossil fuel generation. Thus the new round electric power industry reform is essential in China. The reform involves implementing new pricing mechanism, introducing retail-side competition, promoting the consumption of renewable energy. The new round reform can be a promising solution for promoting the development and consumption of wind energy generation in China. Based on proposed reform policies of electric power industry, this paper suggests a roadmap for retail electricity market reform of China, which consists of three stages. Barriers to the efficient utilization of wind energy are also analysed. Finally, this paper introduces several efficient measures for mitigating wind curtailment in each stage of reform.

Stable Short-Term Frequency Support Using Adaptive Gains for a DFIG-Based Wind Power Plant

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

Lee, Jinsik; Jang, Gilsoo; Muljadi, Eduard

For the fixed-gain inertial control of wind power plants (WPPs), a large gain setting provides a large contribution to supporting system frequency control, but it may cause over-deceleration for a wind turbine generator that has a small amount of kinetic energy (KE). Further, if the wind speed decreases during inertial control, even a small gain may cause over-deceleration. This paper proposes a stable inertial control scheme using adaptive gains for a doubly fed induction generator (DFIG)-based WPP. The scheme aims to improve the frequency nadir (FN) while ensuring stable operation of all DFIGs, particularly when the wind speed decreases duringmore » inertial control. In this scheme, adaptive gains are set to be proportional to the KE stored in DFIGs, which is spatially and temporally dependent. To improve the FN, upon detecting an event, large gains are set to be proportional to the KE of DFIGs; to ensure stable operation, the gains decrease with the declining KE. The simulation results demonstrate that the scheme improves the FN while ensuring stable operation of all DFIGs in various wind and system conditions. Further, it prevents over-deceleration even when the wind speed decreases during inertial control.« less

A hybrid framework for coupling arbitrary summation-by-parts schemes on general meshes

NASA Astrophysics Data System (ADS)

Lundquist, Tomas; Malan, Arnaud; Nordström, Jan

2018-06-01

We develop a general interface procedure to couple both structured and unstructured parts of a hybrid mesh in a non-collocated, multi-block fashion. The target is to gain optimal computational efficiency in fluid dynamics simulations involving complex geometries. While guaranteeing stability, the proposed procedure is optimized for accuracy and requires minimal algorithmic modifications to already existing schemes. Initial numerical investigations confirm considerable efficiency gains compared to non-hybrid calculations of up to an order of magnitude.

Rare-Earth Doped Gallium Nitride (GaN)- An Innovative Path Toward Area-scalable Solid-state High Energy Lasers Without Thermal Distortion

DTIC Science & Technology

2009-04-01

technique and its efficiency , the gain medium itself is the bottleneck for non-distortive heat removal—due to the low thermal conductivity of known gain...photoluminescence (PL), electroluminescence (EL), and/or cathodoluminescence (CL) (2,3). As the RE dopant, Nd is an excellent candidate due to its success...highest level of laser efficiency due to the pump and signal mode confinement within a crystalline-guided structure). The successful implementation of

Efficiency gain of solid oxide fuel cell systems by using anode offgas recycle - Results for a small scale propane driven unit

NASA Astrophysics Data System (ADS)

Dietrich, Ralph-Uwe; Oelze, Jana; Lindermeir, Andreas; Spitta, Christian; Steffen, Michael; Küster, Torben; Chen, Shaofei; Schlitzberger, Christian; Leithner, Reinhard

The transfer of high electrical efficiencies of solid oxide fuel cells (SOFC) into praxis requires appropriate system concepts. One option is the anode-offgas recycling (AOGR) approach, which is based on the integration of waste heat using the principle of a chemical heat pump. The AOGR concept allows a combined steam- and dry-reforming of hydrocarbon fuel using the fuel cell products steam and carbon dioxide. SOFC fuel gas of higher quantity and quality results. In combination with internal reuse of waste heat the system efficiency increases compared to the usual path of partial oxidation (POX). The demonstration of the AOGR concept with a 300 Wel-SOFC stack running on propane required: a combined reformer/burner-reactor operating in POX (start-up) and AOGR modus; a hotgas-injector for anode-offgas recycling to the reformer; a dynamic process model; a multi-variable process controller; full system operation for experimental proof of the efficiency gain. Experimental results proof an efficiency gain of 18 percentage points (η·POX = 23%, η·AOGR = 41%) under idealized lab conditions. Nevertheless, further improvements of injector performance, stack fuel utilization and additional reduction of reformer reformer O/C ratio and system pressure drop are required to bring this approach into self-sustaining operation.

Genetic response to selection for weaning weight or yearling weight or yearling weight and muscle score in Hereford cattle: efficiency of gain, growth, and carcass characteristics.

PubMed

Koch, R M; Cundiff, L V; Gregory, K E; Van Vleck, L D

2004-03-01

An experiment involving crosses among selection and control lines was conducted to partition direct and maternal additive genetic response to 20 yr of selection for 1) weaning weight, 2) yearling weight, and 3) index of yearling weight and muscle score. Selection response was evaluated for efficiency of gain, growth from birth through market weight, and carcass characteristics. Heritability and genetic correlations among traits were estimated using animal model analyses. Over a time-constant interval, selected lines were heavier, gained more weight, consumed more ME, and had more gain/ME than the control. Over a weight-constant interval, selected lines required fewer days, consumed less ME, had more efficient gains, and required less energy for maintenance than control. Direct and maternal responses were estimated from reciprocal crosses among unselected sires and dams of control and selection lines. Most of the genetic response to selection in all three lines was associated with direct genetic effects, and the highest proportion was from postweaning gain. Indirect responses of carcass characteristics to selection over the 20 yr were increased weight of carcasses that had more lean meat, produced with less feed per unit of gain. At a constant carcass weight, selected lines had 1.32 to 1.85% more retail product and 1.62 to 2.24% less fat trim and 10/100 to 25/100 degrees less marbling than control. At a constant age, heritability of direct and maternal effects and correlations between them were as follows: market weight, 0.36, 0.14, and 0.10; carcass weight, 0.26, 0.15, and 0.03; longissimus muscle area, 0.33, 0.00, and 0.00; marbling, 0.36, 0.07, and -0.35; fat thickness, 0.41, 0.05, and -0.18; percentage of kidney, pelvic, and heart fat, 0.12, 0.08, and -0.76; percentage of retail product, 0.46, 0.05, and -0.29; retail product weight, 0.44, 0.08, -0.14; and muscle score, 0.37, 0.14, and -0.54. Selection criteria in all lines improved efficiency of postweaning gain and increased the amount of salable lean meat on an age- or weight-constant basis, but carcasses had slightly lower marbling scores.

A CMOS power-efficient low-noise current-mode front-end amplifier for neural signal recording.

PubMed

Wu, Chung-Yu; Chen, Wei-Ming; Kuo, Liang-Ting

2013-04-01

In this paper, a new current-mode front-end amplifier (CMFEA) for neural signal recording systems is proposed. In the proposed CMFEA, a current-mode preamplifier with an active feedback loop operated at very low frequency is designed as the first gain stage to bypass any dc offset current generated by the electrode-tissue interface and to achieve a low high-pass cutoff frequency below 0.5 Hz. No reset signal or ultra-large pseudo resistor is required. The current-mode preamplifier has low dc operation current to enhance low-noise performance and decrease power consumption. A programmable current gain stage is adopted to provide adjustable gain for adaptive signal scaling. A following current-mode filter is designed to adjust the low-pass cutoff frequency for different neural signals. The proposed CMFEA is designed and fabricated in 0.18-μm CMOS technology and the area of the core circuit is 0.076 mm(2). The measured high-pass cutoff frequency is as low as 0.3 Hz and the low-pass cutoff frequency is adjustable from 1 kHz to 10 kHz. The measured maximum current gain is 55.9 dB. The measured input-referred current noise density is 153 fA /√Hz , and the power consumption is 13 μW at 1-V power supply. The fabricated CMFEA has been successfully applied to the animal test for recording the seizure ECoG of Long-Evan rats.

More steam for Kern River

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

Rintoul, B.

1973-02-01

While production generally is declining elsewhere in California, the Kern River field continues to post gains. The field last year produced at an all-time high for the second year in a row, putting out at least 1.5 million bbl more than in its previous peak year. There is every reason to believe that gains will continue through this year. Steam is in the factor that underlies Kern River's resurgence, and Getty Oil Co., the field's premier steamer, recently added to its already imposing array of steam-generating equipment a pair of large boilers, each capable of generating 240 million btus permore » hr. Along with expansion of the steaming effort the company also expanded its water-treating facilities, making sure there will be plenty of feed water to fuel the steam generators at work in the field. The new boilers are being used to furnish steam to 136 wells in a steam displacement project. The purpose of going to a larger generator has been to gain higher efficiency. The components that have made Getty Oil the leading steamer at Kern River and the field, in turn, the world capital for oil-field steam operations include shallow wells, steam generators and--since 1969--a computer. The entire project is described in detail.« less

Framework and implementation for improving physics essential skills via computer-based practice: Vector math

NASA Astrophysics Data System (ADS)

Mikula, Brendon D.; Heckler, Andrew F.

2017-06-01

We propose a framework for improving accuracy, fluency, and retention of basic skills essential for solving problems relevant to STEM introductory courses, and implement the framework for the case of basic vector math skills over several semesters in an introductory physics course. Using an iterative development process, the framework begins with a careful identification of target skills and the study of specific student difficulties with these skills. It then employs computer-based instruction, immediate feedback, mastery grading, and well-researched principles from cognitive psychology such as interleaved training sequences and distributed practice. We implemented this with more than 1500 students over 2 semesters. Students completed the mastery practice for an average of about 13 min /week , for a total of about 2-3 h for the whole semester. Results reveal large (>1 SD ) pretest to post-test gains in accuracy in vector skills, even compared to a control group, and these gains were retained at least 2 months after practice. We also find evidence of improved fluency, student satisfaction, and that awarding regular course credit results in higher participation and higher learning gains than awarding extra credit. In all, we find that simple computer-based mastery practice is an effective and efficient way to improve a set of basic and essential skills for introductory physics.

Aerodynamic-structural study of canard wing, dual wing, and conventional wing systems for general aviation applications

NASA Technical Reports Server (NTRS)

Selberg, B. P.; Cronin, D. L.

1985-01-01

An analytical aerodynamic-structural airplane configuration study was conducted to assess performance gains achievable through advanced design concepts. The mission specification was for 350 mph, range of 1500 st. mi., at altitudes between 30,000 and 40,000 ft. Two payload classes were studied - 1200 lb (6 passengers) and 2400 lb (12 passengers). The configurations analyzed included canard wings, closely coupled dual wings, swept forward - swept rearward wings, joined wings, and conventional wing tail arrangements. The results illustrate substantial performance gains possible with the dual wing configuration. These gains result from weight savings due to predicted structural efficiencies. The need for further studies of structural efficiencies for the various advanced configurations was highlighted.

Simple and efficient L-band erbium-doped fiber amplifiers for WDM networks

NASA Astrophysics Data System (ADS)

Choi, H. B.; Oh, J. M.; Lee, D.; Ahn, S. J.; Park, B. S.; Lee, S. B.

2002-11-01

The performance of L-band erbium-doped fiber amplifier (EDFA) of a simple structure with a fiber Bragg grating (FBG) was investigated. The injected C-band ASE by the FBG offers low-cost amplification and greatly improves the efficiency of the EDFA. There are 9 and 4 dB improvements with the FBG at 1587 nm, at low and high input, respectively. The flat gain of 18 dB, up to a total input of -5 dBm at 150 mW of 980 nm pump, is obtained over 30 nm with less than ±0.5 dB gain variations without any gain equalizer. The proposed EDFA provides a cost-effective solution for wavelength division multiplexing systems.

The NASA Aircraft Energy Efficiency program

NASA Technical Reports Server (NTRS)

Klineberg, J. M.

1979-01-01

A review is provided of the goals, objectives, and recent progress in each of six aircraft energy efficiency programs aimed at improved propulsive, aerodynamic and structural efficiency for future transport aircraft. Attention is given to engine component improvement, an energy efficient turbofan engine, advanced turboprops, revolutionary gains in aerodynamic efficiency for aircraft of the late 1990s, laminar flow control, and composite primary aircraft structures.

Multiscale three-dimensional simulations of charge gain and transport in diamond

NASA Astrophysics Data System (ADS)

Dimitrov, D. A.; Busby, R.; Cary, J. R.; Ben-Zvi, I.; Rao, T.; Smedley, J.; Chang, X.; Keister, J. W.; Wu, Q.; Muller, E.

2010-10-01

A promising new concept of a diamond-amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. Detailed understanding of physical processes with multiple energy and time scales is required to design reliable and efficient diamond-amplifier cathodes. We have implemented models, within the VORPAL computational framework, to simulate secondary electron generation and charge transport in diamond in order to facilitate the investigation of the relevant effects involved. The models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We describe the integrated modeling capabilities we developed and present results on charge gain and collection efficiency as a function of primary electron energy and applied electric field. We compare simulation results with available experimental data. The simulations show an overall qualitative agreement with the observed charge gain from transmission mode experiments and have enabled better understanding of the collection efficiency measurements.

Towards on-chip integration of brain imaging photodetectors using standard CMOS process.

PubMed

Kamrani, Ehsan; Lesage, Frederic; Sawan, Mohamad

2013-01-01

The main effects of on-chip integration on the performance and efficiency of silicon avalanche photodiode (SiAPD) and photodetector front-end is addressed in this paper based on the simulation and fabrication experiments. Two different silicon APDs are fabricated separately and also integrated with a transimpedance amplifier (TIA) front-end using standard CMOS technology. SiAPDs are designed in p+/n-well structure with guard rings realized in different shapes. The TIA front-end has been designed using distributed-gain concept combined with resistive-feedback and common-gate topology to reach low-noise and high gain-bandwidth product (GBW) characteristics. The integrated SiAPDs show higher signal-to-noise ratio (SNR), sensitivity and detection efficiency comparing to the separate SiAPDs. The integration does not show a significant effect on the gain and preserves the low power consumption. Using APDs with p-well guard-ring is preferred due to the higher observed efficiency after integration.

Efficient design of gain-flattened multi-pump Raman fiber amplifiers using least squares support vector regression

NASA Astrophysics Data System (ADS)

Chen, Jing; Qiu, Xiaojie; Yin, Cunyi; Jiang, Hao

2018-02-01

An efficient method to design the broadband gain-flattened Raman fiber amplifier with multiple pumps is proposed based on least squares support vector regression (LS-SVR). A multi-input multi-output LS-SVR model is introduced to replace the complicated solving process of the nonlinear coupled Raman amplification equation. The proposed approach contains two stages: offline training stage and online optimization stage. During the offline stage, the LS-SVR model is trained. Owing to the good generalization capability of LS-SVR, the net gain spectrum can be directly and accurately obtained when inputting any combination of the pump wavelength and power to the well-trained model. During the online stage, we incorporate the LS-SVR model into the particle swarm optimization algorithm to find the optimal pump configuration. The design results demonstrate that the proposed method greatly shortens the computation time and enhances the efficiency of the pump parameter optimization for Raman fiber amplifier design.

PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Efficiency of the vibrational excitation of CO2 molecules pumped by a capacitative discharge

NASA Astrophysics Data System (ADS)

Baranov, G. A.; Efremov, Yu V.; Smirnov, A. S.; Frolov, K. S.; Shevchenko, Yu I.

1989-02-01

An investigation was made of the distributions of the gain and input energy per unit volume along the discharge chamber length in a CO2-N2-He mixture stream excited by an rf discharge. The dependences of the gain and discharge luminescence intensity on the coordinate x were determined along the direction of the gas flow. The discharge luminescence intensity was shown to characterize the input energy distribution along the X axis. Calculations were made of the small-signal gain in the rf discharge. Experimental data on the distributions of the input energy and of the electric field in the discharge and the average values of the kinetic coefficients were used in the calculations. The efficiency of pumping CO2 lasers with an rf discharge was found to be close to the dc pumping efficiency. The results obtained provide evidence of promising prospects for using an rf discharge in fast-flow industrial lasers.

Will Systems Biology Deliver Its Promise and Contribute to the Development of New or Improved Vaccines? What Really Constitutes the Study of "Systems Biology" and How Might Such an Approach Facilitate Vaccine Design.

PubMed

Germain, Ronald N

2017-10-16

A dichotomy exists in the field of vaccinology about the promise versus the hype associated with application of "systems biology" approaches to rational vaccine design. Some feel it is the only way to efficiently uncover currently unknown parameters controlling desired immune responses or discover what elements actually mediate these responses. Others feel that traditional experimental, often reductionist, methods for incrementally unraveling complex biology provide a more solid way forward, and that "systems" approaches are costly ways to collect data without gaining true insight. Here I argue that both views are inaccurate. This is largely because of confusion about what can be gained from classical experimentation versus statistical analysis of large data sets (bioinformatics) versus methods that quantitatively explain emergent properties of complex assemblies of biological components, with the latter reflecting what was previously called "physiology." Reductionist studies will remain essential for generating detailed insight into the functional attributes of specific elements of biological systems, but such analyses lack the power to provide a quantitative and predictive understanding of global system behavior. But by employing (1) large-scale screening methods for discovery of unknown components and connections in the immune system ( omics ), (2) statistical analysis of large data sets ( bioinformatics ), and (3) the capacity of quantitative computational methods to translate these individual components and connections into models of emergent behavior ( systems biology ), we will be able to better understand how the overall immune system functions and to determine with greater precision how to manipulate it to produce desired protective responses. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

How Much Is Too Much Assessment? Insight into Assessment-Driven Student Learning Gains in Large-Scale Undergraduate Microbiology Courses

PubMed Central

Wang, Jack T. H.; Schembri, Mark A.; Hall, Roy A.

2013-01-01

Designing and implementing assessment tasks in large-scale undergraduate science courses is a labor-intensive process subject to increasing scrutiny from students and quality assurance authorities alike. Recent pedagogical research has provided conceptual frameworks for teaching introductory undergraduate microbiology, but has yet to define best-practice assessment guidelines. This study assessed the applicability of Biggs’ theory of constructive alignment in designing consistent learning objectives, activities, and assessment items that aligned with the American Society for Microbiology’s concept-based microbiology curriculum in MICR2000, an introductory microbiology course offered at the University of Queensland, Australia. By improving the internal consistency in assessment criteria and increasing the number of assessment items explicitly aligned to the course learning objectives, the teaching team was able to efficiently provide adequate feedback on numerous assessment tasks throughout the semester, which contributed to improved student performance and learning gains. When comparing the constructively aligned 2011 offering of MICR2000 with its 2010 counterpart, students obtained higher marks in both coursework assignments and examinations as the semester progressed. Students also valued the additional feedback provided, as student rankings for course feedback provision increased in 2011 and assessment and feedback was identified as a key strength of MICR2000. By designing MICR2000 using constructive alignment and iterative assessment tasks that followed a common set of learning outcomes, the teaching team was able to effectively deliver detailed and timely feedback in a large introductory microbiology course. This study serves as a case study for how constructive alignment can be integrated into modern teaching practices for large-scale courses. PMID:23858350

Tracking truck flows with programmable mobile devices for drayage efficiency analysis: [research brief].

DOT National Transportation Integrated Search

2016-05-01

The purpose of this project is to design and experiment on a technology to track, organize, : extract and analyze data on port drayage activities from which a clear understanding of drayage : efficiency can be gained. Drayage efficiency may point to ...

Design and performance of SiPM-based readout of PbF 2 crystals for high-rate, precision timing applications

DOE PAGES

Kaspar, J.; Fienberg, A. T.; Hertzog, D. W.; ...

2017-01-11

Here, we have developed a custom amplifier board coupled to a large-format 16-channel Hamamatsu silicon photomultiplier device for use as the light sensor for the electromagnetic calorimeters in the Muon g-2 experiment at Fermilab. The calorimeter absorber is an array of lead-fluoride crystals, which produces short-duration Cherenkov light. The detector sits in the high magnetic field of the muon storage ring. The SiPMs selected, and their accompanying custom electronics, must preserve the short pulse shape, have high quantum efficiency, be non-magnetic, exhibit gain stability under varying rate conditions, and cover a fairly large fraction of the crystal exit surface area.more » We describe an optimized design that employs the new-generation of thru-silicon via devices. As a result, the performance is documented in a series of bench and beam tests.« less

Production and Purification of Recombinant SUMOylated Proteins Using Engineered Bacteria.

PubMed

Brockly, Frédérique; Piechaczyk, Marc; Bossis, Guillaume

2016-01-01

SUMO is a ubiquitin-like protein that is covalently conjugated to numerous cellular proteins to modify their function and fate. Although large progresses have been made in the identification of SUMOylated proteins, the molecular consequences of their SUMOylation are generally unknown. This is, most often, due to the low abundance of SUMOylated proteins in the cell, usually less than 1 % of a given protein being modified at steady state. To gain insights into the role of specific SUMOylation targets, SUMO conjugation can be reconstituted in vitro using purified proteins. However, for most substrates, the efficiency of in vitro SUMOylation is too low to obtain sufficient amounts of their SUMOylated forms for biochemical studies. Here, we describe a detailed protocol to purify large amounts of recombinant SUMOylated proteins using bacteria modified to express His-tagged SUMO as well as the SUMO-activating and -conjugating enzymes.

Launch processing system transition from development to operation

NASA Technical Reports Server (NTRS)

Paul, H. C.

1977-01-01

The Launch Processing System has been under development at Kennedy Space Center since 1973. A prototype system was developed and delivered to Marshall Space Flight Center for Solid Rocket Booster checkout in July 1976. The first production hardware arrived in late 1976. The System uses a distributed computer network for command and monitoring and is supported by a dual large scale computer system for 'off line' processing. A high level of automation is anticipated for Shuttle and Payload testing and launch operations to gain the advantages of short turnaround capability, repeatability of operations, and minimization of operations and maintenance (O&M) manpower. Learning how to efficiently apply the system is our current problem. We are searching for more effective ways to convey LPS system performance characteristics from the designer to a large number of users. Once we have done this, we can realize the advantages of LPS system design.

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

Tyson, T. A.; Gao, W.; Chen, Y. -S.

Solar cells based on hybrid perovskites have shown high efficiency while possessing simple processing methods. To gain a fundamental understanding of their properties on an atomic level, we investigate single crystals of CH 3NH 3PbI 3 with a narrow transition (~5 K) near 327 K. Temperature dependent structural measurements reveal a persistent tetragonal structure with smooth changes in the atomic displacement parameters (ADPs) on crossing T*. We show that the ADPs for I ions yield extended flat regions in the potential wells consistent with the measured large thermal expansion parameter. Molecular dynamics simulations reveal that this material exhibits significant asymmetriesmore » in the Pb-I pair distribution functions. We also show that the intrinsically enhanced freedom of motion of the iodine atoms enables large deformations. This flexibility (softness) of the atomic structure results in highly localized atomic relaxation about defects and hence accounts for both the high carrier mobility as well as the structural instability.« less

Dynamic impacts of a catastrophic production event: the foot-and-mouth disease case.

PubMed

Cordier, Alexandre; Gohin, Jean; Krebs, Stephane; Rault, Arnaud

2013-03-01

In foot-and-mouth disease (FMD) free countries, the occurrence of an FMD outbreak is a rare event with potentially large economic losses. We explore the dynamic effects of an FMD outbreak on market variables and economic surplus taking into account the largely neglected issue of farm bankruptcy. Simulations are performed on a stylized agricultural economy, which is a net exporter before the outbreak. We find complex dynamic market effects when the farm credit market suffers from information imperfections leading to farm closure. Welfare effects are also dramatically altered. Domestic consumers may lose in the long run from an FMD outbreak because domestic supply contracts. On the other hand, farmers able to resist this event may ultimately gain. Our analysis also shows that these effects are not monotone, making any efficient policy response to this catastrophic event quite challenging. © 2012 Society for Risk Analysis.

Control of fluxes in metabolic networks

PubMed Central

Basler, Georg; Nikoloski, Zoran; Larhlimi, Abdelhalim; Barabási, Albert-László; Liu, Yang-Yu

2016-01-01

Understanding the control of large-scale metabolic networks is central to biology and medicine. However, existing approaches either require specifying a cellular objective or can only be used for small networks. We introduce new coupling types describing the relations between reaction activities, and develop an efficient computational framework, which does not require any cellular objective for systematic studies of large-scale metabolism. We identify the driver reactions facilitating control of 23 metabolic networks from all kingdoms of life. We find that unicellular organisms require a smaller degree of control than multicellular organisms. Driver reactions are under complex cellular regulation in Escherichia coli, indicating their preeminent role in facilitating cellular control. In human cancer cells, driver reactions play pivotal roles in malignancy and represent potential therapeutic targets. The developed framework helps us gain insights into regulatory principles of diseases and facilitates design of engineering strategies at the interface of gene regulation, signaling, and metabolism. PMID:27197218

Efficient Sub-Bandgap Light Absorption and Signal Amplification in Silicon Photodetectors

NASA Astrophysics Data System (ADS)

Liu, Yu-Hsin

This thesis focuses on two areas in silicon photodetectors, the first being enhancing the sub-bandgap light absorption of IR wavelenghts in silicon, and the second being intrinsic signal amplification in silicon photodetectors. Both of these are achieved using heavily doped p-n junction devices which create localized states that relax the k-selection rule of indirect bandgap material. The probability of transitions between impurity band and the conduction/valence band would be much more efficient than the one between band-to-band transition. The waveguide-coupled epitaxial p-n photodetector was demonstrated for 1310 nm wavelength detection. Incorporated with the Franz-Keldysh effect and the quasi-confined epitaxial layer design, an absorption coefficient around 10 cm-1 has been measured and internal quantum efficiency nearly 100% at -2.5V. The absorption coefficient is calculated from the wave function of the electron and hole in p-n diode. The heavily doped impurity wave function can be formulated as a delta function, and the quasi-confined conduction band energy states, and the wave function on each level can be obtained from the Silvaco software. The calculated theoretical absorption coefficient increases with the increasing applied bias and the doping concentration, which matches the experimental results. To solve the issues of large excess noise and high operation bias for avalanche photodiodes based on impact ionization, I presented a detector using the Cycling Excitation Process (CEP) for signal amplification. This can be realized in a heavily doped and highly compensated Si p-n junction, showing ultra high gain about 3000 at very low bias (<4 V), and possessing an intrinsic, phonon-mediated regulation process to keep the device stable without any quenching device required in today's Geiger-mode avalanche detectors. The CEP can be formulated with the rate equations in conduction bands and impurity states. The gain expression, which is a function of the primary photocurrent and related to the phonon absorption time, predicts the same trend of the gain increasing with temperature and decreasing with increasing primary photocurrent.

Microreactor System Design for a NASA In Situ Propellant Production Plant on Mars

NASA Technical Reports Server (NTRS)

TeGrotenhuis, W. E.; Wegeng, R. S.; Vanderwiel, D. P.; Whyatt, G. A.; Viswanathan, V. V.; Schielke, K. P.; Sanders, G. B.; Peters, T. A.; Nicholson, Leonard S. (Technical Monitor)

2000-01-01

The NASA In Situ Resource Utilization (ISRU) program is planning near-term missions to Mars that will include chemical processes for converting the carbon dioxide (CO2) and possibly water from the Martian environment to propellants, oxygen, and other useful chemicals. The use of indigenous resources reduces the size and weight of the payloads from Earth significantly, representing enormous cost savings that make human exploration of Mars affordable. Extraterrestrial chemical processing plants will need to be compact, lightweight, highly efficient under reduced gravity, and extraordinarily reliable for long periods. Microchemical and thermal systems represent capability for dramatic reduction in size and weight, while offering high reliability through massive parallelization. In situ propellant production (ISPP), one aspect of the ISRU program, involves collecting and pressurizing atmospheric CO2, conversion reactions, chemical separations, heat exchangers, and cryogenic storage. A preliminary system design of an ISPP plant based on microtechnology has demonstrated significant size, weight, and energy efficiency gains over the current NASA baseline. Energy management is a strong driver for Mars-based processes, not only because energy is a scarce resource, but because heat rejection is problematic; the low pressure environment makes convective heat transfer ineffective. Energy efficiency gains are largely achieved in the microchemical plant through extensive heat recuperation and energy cascading, which has a small size and weight penalty because the added micro heat exchangers are small. This leads to additional size and weight gains by reducing the required area of waste heat radiators. The microtechnology-based ISPP plant is described in detail, including aspects of pinch analysis for optimizing the heat exchanger network. Three options for thermochemical compression Of CO2 from the Martian atmosphere, adsorption, absorption, and cryogenic freezing, are presented, as well as three options for water decomposition, low temperature electrolysis, high temperature electrolysis, and thermochemical decomposition. Other elements of the plant include Sabatier and reverse water gas shift reactors, water recovery, chemical separations, and cryogenic storage. Data are presented supporting preliminary sizing of components, and results of the system design are compared to the existing NASA baseline that is based on conventional technologies.

High Efficiency Automatic-Power-Controlled and Gain-Clamped EDFA for Broadband Passive Optical Networking Systems

NASA Astrophysics Data System (ADS)

Shen, Jyi-Lai; Wei, Shui-Ken; Lin, Chin-Yuan; Iong Li, Ssu; Huang, Chih-Chuan

2010-04-01

The configuration of a simple improved high efficiency automatic-power-controlled and gain-clamped EDFA (APC-GC-EDFA) for broadband passive optical networking systems (BPON) is presented here. In order to compensate the phase and amplitude variation due to the different distance between the optical line terminal (OLT) and optical network units (ONU), the APC-GC-EDFA need to be employed. A single 980 nm laser module is employed as the primary pump. To extend the bandwidth, all C-band ASE is recycled as the secondary pump to enhance the gain efficiency. An electrical feedback circuit is used as a multi-wavelength channel transmitter monitor for the automatic power control to improve the gain-flattened flatness for stable amplification. The experimental results prove that the EDFA system can provide flatter clamped gain in both C-band and L-band configurations. The gain flatness wavelength ranging from 1530 to 1610 nm is within 32.83 ± 0.64 dB, i.e. below 1.95 %. The gains are clamped at 33.85 ± 0.65 dB for the input signal power of -40 dBm to -10 dBm. The range of noise figure is between 6.37 and 6.56, which is slightly lower compared to that of unclamped amplifiers. This will be very useful for measuring the gain flatness of APC-GC-EDFA. Finally, we have also demonstrated the records of the overall simultaneous dynamics measurements for the new system stabilization. The carrier to noise ratio (CNR) is 49.5 to 50.8 dBc which is above the National Television System Committee (NTSC) standard of 43 dBc, and both composite second order (CSO) 69.2 to 71.5 dBc and composite triple beat (CTB) of 69.8 to 72.2 dBc are above 53 dBc. The recorded corresponding rise-time of 1.087 ms indicates that the system does not exhibit any overshoot of gain or ASE variation due to the signal at the beginning of the pulse.

Hydrogen Epoch of Reinozation Array (HERA) Calibrated FFT Correlator Simulation

NASA Astrophysics Data System (ADS)

Salazar, Jeffrey David; Parsons, Aaron

2018-01-01

The Hydrogen Epoch of Reionization Array (HERA) project is an astronomical radio interferometer array with a redundant baseline configuration. Interferometer arrays are being used widely in radio astronomy because they have a variety of advantages over single antenna systems. For example, they produce images (visibilities) closely matching that of a large antenna (such as the Arecibo observatory), while both the hardware and maintenance costs are significantly lower. However, this method has some complications; one being the computational cost of correlating data from all of the antennas. A correlator is an electronic device that cross-correlates the data between the individual antennas; these are what radio astronomers call visibilities. HERA, being in its early stages, utilizes a traditional correlator system. The correlator cost scales as N2, where N is the number of antennas in the array. The purpose of a redundant baseline configuration array setup is for the use of a more efficient Fast Fourier Transform (FFT) correlator. FFT correlators scale as Nlog2N. The data acquired from this sort of setup, however, inherits geometric delay and uncalibrated antenna gains. This particular project simulates the process of calibrating signals from astronomical sources. Each signal “received” by an antenna in the simulation is given random antenna gain and geometric delay. The “linsolve” Python module was used to solve for the unknown variables in the simulation (complex gains and delays), which then gave a value for the true visibilities. This first version of the simulation only mimics a one dimensional redundant telescope array detecting a small amount of sources located in the volume above the antenna plane. Future versions, using GPUs, will handle a two dimensional redundant array of telescopes detecting a large amount of sources in the volume above the array.

K-Band Power Enbedded Transmission Line (ETL) MMIC Amplifiers for Satellite Communication Applications

NASA Technical Reports Server (NTRS)

Tserng, Hua-Quen; Ketterson, Andrew; Saunier, Paul; McCarty, Larry; Davis, Steve

1998-01-01

The design, fabrication, and performance of K-band high-efficiency, linear power pHEMT amplifiers implemented in Embedded Transmission Line (ETL) MMIC configuration with unthinned GaAs substrate and topside grounding are reported. A three-stage amplifier achieved a power-added efficiency of 40.5% with 264 mW output at 20.2 GHz. The linear gain is 28.5 dB with 1-dB gain compression output power of 200 mW and 31% power-added efficiency. The carrier-to-third-order intermodulation ratio is approx. 20 dBc at the 1-dB compression point. A RF functional yield of more than 90% has been achieved.

Proton-pumping mechanism of cytochrome c oxidase: A kinetic master-equation approach

PubMed Central

Kim, Young C.; Hummer, Gerhard

2011-01-01

Cytochrome c oxidase (CcO) is an efficient energy transducer that reduces oxygen to water and converts the released chemical energy into an electrochemical membrane potential. As a true proton pump, CcO translocates protons across the membrane against this potential. Based on a wealth of experiments and calculations, an increasingly detailed picture of the reaction intermediates in the redox cycle has emerged. However, the fundamental mechanism of proton pumping coupled to redox chemistry remains largely unresolved. Here we examine and extend a kinetic master-equation approach to gain insight into redox-coupled proton pumping in CcO. Basic principles of the CcO proton pump emerge from an analysis of the simplest kinetic models that retain essential elements of the experimentally determined structure, energetics, and kinetics, and that satisfy fundamental physical principles. The master-equation models allow us to address the question of how pumping can be achieved in a system in which all reaction steps are reversible. Whereas proton pumping does not require the direct modulation of microscopic reaction barriers, such kinetic gating greatly increases the pumping efficiency. Further efficiency gains can be achieved by partially decoupling the proton uptake pathway from the ative-site region. Such a mechanism is consistent with the proposed Glu valve, in which the side chain of a key glutamic acid shuttles between the D channel and the active-site region. We also show that the models predict only small proton leaks even in the absence of turnover. The design principles identified here for CcO provide a blueprint for novel biology-inspired fuel cells, and the master-equation formulation should prove useful also for other molecular machines. PMID:21946020

Approaches to mitigate freight congestion.

DOT National Transportation Integrated Search

2008-11-20

Strong productivity gains in the U.S. economy hinge, in part, on transportation networks working efficiently. Continued development and efficient management of the nation's freight transportation system, especially highways and rail lines that connec...

21 CFR 558.78 - Bacitracin zinc.

Code of Federal Regulations, 2014 CFR

2014-04-01

... feed efficiency Growing chickens 054771 (ii) 4 to 50 Turkeys and pheasants: for increased rate of weight gain and improved feed efficiency Growing turkeys and pheasants 054771 (iii) 5 to 20 Quail; for...

WE-E-18A-01: Large Area Avalanche Amorphous Selenium Sensors for Low Dose X-Ray Imaging

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

Scheuermann, J; Goldan, A; Zhao, W

2014-06-15

Purpose: A large area indirect flat panel imager (FPI) with avalanche gain is being developed to achieve x-ray quantum noise limited low dose imaging. It uses a thin optical sensing layer of amorphous selenium (a-Se), known as High-Gain Avalanche Rushing Photoconductor (HARP), to detect optical photons generated from a high resolution x-ray scintillator. We will report initial results in the fabrication of a solid-state HARP structure suitable for a large area FPI. Our objective is to establish the blocking layer structures and defect suppression mechanisms that provide stable and uniform avalanche gain. Methods: Samples were fabricated as follows: (1) ITOmore » signal electrode. (2) Electron blocking layer. (3) A 15 micron layer of intrinsic a-Se. (4) Transparent hole blocking layer. (5) Multiple semitransparent bias electrodes to investigate avalanche gain uniformity over a large area. The sample was exposed to 50ps optical excitation pulses through the bias electrode. Transient time of flight (TOF) and integrated charge was measured. A charge transport simulation was developed to investigate the effects of varying blocking layer charge carrier mobility on defect suppression, avalanche gain and temporal performance. Results: Avalanche gain of ∼200 was achieved experimentally with our multi-layer HARP samples. Simulations using the experimental sensor structure produced the same magnitude of gain as a function of electric field. The simulation predicted that the high dark current at a point defect can be reduced by two orders of magnitude by blocking layer optimization which can prevent irreversible damage while normal operation remained unaffected. Conclusion: We presented the first solid state HARP structure directly scalable to a large area FPI. We have shown reproducible and uniform avalanche gain of 200. By reducing mobility of the blocking layers we can suppress defects and maintain stable avalanche. Future work will optimize the blocking layers to prevent lag and ghosting.« less

A Case Study in Market Transformation for Residential Energy Efficiency Programs

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

Building Technologies Office

This case study describes how the Midwest Energy Efficiency Alliance (MEEA) partnered with gas and electric utilities in Iowa to establish the Iowa residential heating, ventilation, and air conditioning System Adjustment and Verified Efficiency (HVAC SAVE) program, taking it to scale improving the performance and energy efficiency of HVAC systems, growing businesses, and gaining consumer trust.

WE-E-18A-07: MAGIC: Multi-Acquisition Gain Image Correction for Mobile X-Ray Systems with Intrinsic Localization Crosshairs

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

Park, Y; Sharp, G

2014-06-15

Purpose: Gain calibration for X-ray imaging systems with movable flat panel detectors (FPD) and intrinsic crosshairs is a challenge due to the geometry dependence of the heel effect and crosshair artifact. This study aims to develop a gain correction method for such systems by implementing the multi-acquisition gain image correction (MAGIC) technique. Methods: Raw flat-field images containing crosshair shadows and heel effect were acquired in 4 different FPD positions with fixed exposure parameters. The crosshair region was automatically detected and substituted with interpolated values from nearby exposed regions, generating a conventional single-image gain-map for each FPD position. Large kernel-based correctionmore » was applied to these images to correct the heel effect. A mask filter was used to invalidate the original cross-hair regions previously filled with the interpolated values. A final, seamless gain-map was created from the processed images by either the sequential filling (SF) or selective averaging (SA) techniques developed in this study. Quantitative evaluation was performed based on detective quantum efficiency improvement factor (DQEIF) for gain-corrected images using the conventional and proposed techniques. Results: Qualitatively, the MAGIC technique was found to be more effective in eliminating crosshair artifacts compared to the conventional single-image method. The mean DQEIF over the range of frequencies from 0.5 to 3.5 mm-1 were 1.09±0.06, 2.46±0.32, and 3.34±0.36 in the crosshair-artifact region and 2.35±0.31, 2.33±0.31, and 3.09±0.34 in the normal region, for the conventional, MAGIC-SF, and MAGIC-SA techniques, respectively. Conclusion: The introduced MAGIC technique is appropriate for gain calibration of an imaging system associated with a moving FPD and an intrinsic crosshair. The technique showed advantages over a conventional single image-based technique by successfully reducing residual crosshair artifacts, and higher image quality with respect to DQE.« less

Ultra-high gain diffusion-driven organic transistor

PubMed Central

Torricelli, Fabrizio; Colalongo, Luigi; Raiteri, Daniele; Kovács-Vajna, Zsolt Miklós; Cantatore, Eugenio

2016-01-01

Emerging large-area technologies based on organic transistors are enabling the fabrication of low-cost flexible circuits, smart sensors and biomedical devices. High-gain transistors are essential for the development of large-scale circuit integration, high-sensitivity sensors and signal amplification in sensing systems. Unfortunately, organic field-effect transistors show limited gain, usually of the order of tens, because of the large contact resistance and channel-length modulation. Here we show a new organic field-effect transistor architecture with a gain larger than 700. This is the highest gain ever reported for organic field-effect transistors. In the proposed organic field-effect transistor, the charge injection and extraction at the metal–semiconductor contacts are driven by the charge diffusion. The ideal conditions of ohmic contacts with negligible contact resistance and flat current saturation are demonstrated. The approach is general and can be extended to any thin-film technology opening unprecedented opportunities for the development of high-performance flexible electronics. PMID:26829567

A socio-hydrologic model of coupled water-agriculture dynamics with emphasis on farm size.

NASA Astrophysics Data System (ADS)

Brugger, D. R.; Maneta, M. P.

2015-12-01

Agricultural land cover dynamics in the U.S. are dominated by two trends: 1) total agricultural land is decreasing and 2) average farm size is increasing. These trends have important implications for the future of water resources because 1) growing more food on less land is due in large part to increased groundwater withdrawal and 2) larger farms can better afford both more efficient irrigation and more groundwater access. However, these large-scale trends are due to individual farm operators responding to many factors including climate, economics, and policy. It is therefore difficult to incorporate the trends into watershed-scale hydrologic models. Traditional scenario-based approaches are valuable for many applications, but there is typically no feedback between the hydrologic model and the agricultural dynamics and so limited insight is gained into the how agriculture co-evolves with water resources. We present a socio-hydrologic model that couples simplified hydrologic and agricultural economic dynamics, accounting for many factors that depend on farm size such as irrigation efficiency and returns to scale. We introduce an "economic memory" (EM) state variable that is driven by agricultural revenue and affects whether farms are sold when land market values exceed expected returns from agriculture. The model uses a Generalized Mixture Model of Gaussians to approximate the distribution of farm sizes in a study area, effectively lumping farms into "small," "medium," and "large" groups that have independent parameterizations. We apply the model in a semi-arid watershed in the upper Columbia River Basin, calibrating to data on streamflow, total agricultural land cover, and farm size distribution. The model is used to investigate the sensitivity of the coupled system to various hydrologic and economic scenarios such as increasing market value of land, reduced surface water availability, and increased irrigation efficiency in small farms.

Frequency conversion system

NASA Technical Reports Server (NTRS)

Sanders, Steven (Inventor); Waarts, Robert G. (Inventor)

2001-01-01

A frequency conversion system comprises first and second gain sources providing first and second frequency radiation outputs where the second gain source receives as input the output of the first gain source and, further, the second gain source comprises a Raman or Brillouin gain fiber for wave shifting a portion of the radiation of the first frequency output into second frequency radiation output to provided a combined output of first and second frequencies. Powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Doping-enhanced radiative efficiency enables lasing in unpassivated GaAs nanowires

PubMed Central

Burgess, Tim; Saxena, Dhruv; Mokkapati, Sudha; Li, Zhe; Hall, Christopher R.; Davis, Jeffrey A.; Wang, Yuda; Smith, Leigh M.; Fu, Lan; Caroff, Philippe; Tan, Hark Hoe; Jagadish, Chennupati

2016-01-01

Nanolasers hold promise for applications including integrated photonics, on-chip optical interconnects and optical sensing. Key to the realization of current cavity designs is the use of nanomaterials combining high gain with high radiative efficiency. Until now, efforts to enhance the performance of semiconductor nanomaterials have focused on reducing the rate of non-radiative recombination through improvements to material quality and complex passivation schemes. Here we employ controlled impurity doping to increase the rate of radiative recombination. This unique approach enables us to improve the radiative efficiency of unpassivated GaAs nanowires by a factor of several hundred times while also increasing differential gain and reducing the transparency carrier density. In this way, we demonstrate lasing from a nanomaterial that combines high radiative efficiency with a picosecond carrier lifetime ready for high speed applications. PMID:27311597

Factors affecting commercial application of embryo technologies in dairy cattle in Europe--a modelling approach.

PubMed

van Arendonk, Johan A M; Bijma, Piter

2003-01-15

Reproductive techniques have a major impact on the structure of breeding programmes, the rate of genetic gain and dissemination of genetic gain in populations. This manuscript reviews the impact of reproductive technologies on the underlying components of genetic gain and inbreeding with special reference to the role of female reproductive technology. Evaluation of alternative breeding schemes should be based on genetic gain while constraining inbreeding. Optimum breeding schemes can be characterised by: decreased importance of sib information; increased accuracy at the expense of intensity; and a factorial mating strategy. If large-scale embryo cloning becomes feasible, this will have a small impact on the rate of genetic gain but will have a large impact on the structure of breeding programmes.

Prediction-based association control scheme in dense femtocell networks

PubMed Central

Pham, Ngoc-Thai; Huynh, Thong; Hwang, Won-Joo; You, Ilsun; Choo, Kim-Kwang Raymond

2017-01-01

The deployment of large number of femtocell base stations allows us to extend the coverage and efficiently utilize resources in a low cost manner. However, the small cell size of femtocell networks can result in frequent handovers to the mobile user, and consequently throughput degradation. Thus, in this paper, we propose predictive association control schemes to improve the system’s effective throughput. Our design focuses on reducing handover frequency without impacting on throughput. The proposed schemes determine handover decisions that contribute most to the network throughput and are proper for distributed implementations. The simulation results show significant gains compared with existing methods in terms of handover frequency and network throughput perspective. PMID:28328992

Energy Dissipation and Transport in Carbon Nanotube Devices

NASA Astrophysics Data System (ADS)

Pop, Eric

2011-03-01

Power consumption is a significant challenge in electronics, often limiting the performance of integrated circuits from mobile devices to massive data centers. Carbon nanotubes have emerged as potentially energy-efficient future devices and interconnects, with both large mobility and thermal conductivity. This talk will focus on understanding and controlling energy dissipation [1-3] and transport [4-6] in carbon nanotubes, with applications to low-energy devices, interconnects, heat sinks, and memory elements. Experiments have been used to gain new insight into the fundamental behavior of such devices, and to better inform practical device models. The results suggest much room for energy optimization in nanoelectronics through the design of geometry, interfaces, and materials..

Lightweight 3.66-meter-diameter conical mesh antenna reflector

NASA Technical Reports Server (NTRS)

Moore, D. M.

1974-01-01

A description is given of a 3.66 m diameter nonfurlable conical mesh antenna incorporating the line source feed principle recently developed. The weight of the mesh reflector and its support structure is 162 N. An area weighted RMS surface deviation of 0.28 mm was obtained. The RF performance measurements show a gain of 48.3 db at 8.448 GHz corresponding to an efficiency of 66%. During the design and development of this antenna, the technology for fabricating the large conical membranes of knitted mesh was developed. As part of this technology a FORTRAN computer program, COMESH, was developed which permits the user to predict the surface accuracy of a stretched conical membrane.

Evaluation of a near-infrared photomultiplier

NASA Technical Reports Server (NTRS)

Evans, W. E.

1978-01-01

A high performance near infrared sensitive photomultiplier tube was procured and evaluated with emphasis on those characteristics affecting its use over the very large amplitude range of signals encountered by an airborne lidar intended for mapping the distribution of stratospheric aerosols. A cathode quantum efficiency of 4.3 percent at 1.06 micrometer wavelength and a background count of less than 10,000 per second were realized. It is recommended that the tube be stored and operated at a temperature near -20 C, or cooler. Performance was found acceptable for the application in both pulse counting and analog modes, but careful design, probably including dynamic gain control, will be required to effectively utilize both modes on the same lidar shot.

Adaptation of a program for nonlinear finite element analysis to the CDC STAR 100 computer

NASA Technical Reports Server (NTRS)

Pifko, A. B.; Ogilvie, P. L.

1978-01-01

The conversion of a nonlinear finite element program to the CDC STAR 100 pipeline computer is discussed. The program called DYCAST was developed for the crash simulation of structures. Initial results with the STAR 100 computer indicated that significant gains in computation time are possible for operations on gloval arrays. However, for element level computations that do not lend themselves easily to long vector processing, the STAR 100 was slower than comparable scalar computers. On this basis it is concluded that in order for pipeline computers to impact the economic feasibility of large nonlinear analyses it is absolutely essential that algorithms be devised to improve the efficiency of element level computations.

Recent advances in multiview distributed video coding

NASA Astrophysics Data System (ADS)

Dufaux, Frederic; Ouaret, Mourad; Ebrahimi, Touradj

2007-04-01

We consider dense networks of surveillance cameras capturing overlapped images of the same scene from different viewing directions, such a scenario being referred to as multi-view. Data compression is paramount in such a system due to the large amount of captured data. In this paper, we propose a Multi-view Distributed Video Coding approach. It allows for low complexity / low power consumption at the encoder side, and the exploitation of inter-view correlation without communications among the cameras. We introduce a combination of temporal intra-view side information and homography inter-view side information. Simulation results show both the improvement of the side information, as well as a significant gain in terms of coding efficiency.

Climbing plants in a temperate rainforest understorey: searching for high light or coping with deep shade?

PubMed Central

Valladares, Fernando; Gianoli, Ernesto; Saldaña, Alfredo

2011-01-01

Background and Aims While the climbing habit allows vines to reach well-lit canopy areas with a minimum investment in support biomass, many of them have to survive under the dim understorey light during certain stages of their life cycle. But, if the growth/survival trade-off widely reported for trees hold for climbing plants, they cannot maximize both light-interception efficiency and shade avoidance (i.e. escaping from the understorey). The seven most important woody climbers occurring in a Chilean temperate evergreen rainforest were studied with the hypothesis that light-capture efficiency of climbers would be positively associated with their abundance in the understorey. Methods Species abundance in the understorey was quantified from their relative frequency and density in field plots, the light environment was quantified by hemispherical photography, the photosynthetic response to light was measured with portable gas-exchange analyser, and the whole shoot light-interception efficiency and carbon gain was estimated with the 3-D computer model Y-plant. Key Results Species differed in specific leaf area, leaf mass fraction, above ground leaf area ratio, light-interception efficiency and potential carbon gain. Abundance of species in the understorey was related to whole shoot features but not to leaf level features such as specific leaf area. Potential carbon gain was inversely related to light-interception efficiency. Mutual shading among leaves within a shoot was very low (<20 %). Conclusions The abundance of climbing plants in this southern rainforest understorey was directly related to their capacity to intercept light efficiently but not to their potential carbon gain. The most abundant climbers in this ecosystem match well with a shade-tolerance syndrome in contrast to the pioneer-like nature of climbers observed in tropical studies. The climbers studied seem to sacrifice high-light searching for coping with the dim understorey light. PMID:21685433

Modelling the link amongst fine-pore diffuser fouling, oxygen transfer efficiency, and aeration energy intensity.

PubMed

Garrido-Baserba, Manel; Sobhani, Reza; Asvapathanagul, Pitiporn; McCarthy, Graham W; Olson, Betty H; Odize, Victory; Al-Omari, Ahmed; Murthy, Sudhir; Nifong, Andrea; Godwin, Johnnie; Bott, Charles B; Stenstrom, Michael K; Shaw, Andrew R; Rosso, Diego

2017-03-15

This research systematically studied the behavior of aeration diffuser efficiency over time, and its relation to the energy usage per diffuser. Twelve diffusers were selected for a one year fouling study. Comprehensive aeration efficiency projections were carried out in two WRRFs with different influent rates, and the influence of operating conditions on aeration diffusers' performance was demonstrated. This study showed that the initial energy use, during the first year of operation, of those aeration diffusers located in high rate systems (with solids retention time - SRT-less than 2 days) increased more than 20% in comparison to the conventional systems (2 > SRT). Diffusers operating for three years in conventional systems presented the same fouling characteristics as those deployed in high rate processes for less than 15 months. A new procedure was developed to accurately project energy consumption on aeration diffusers; including the impacts of operation conditions, such SRT and organic loading rate, on specific aeration diffusers materials (i.e. silicone, polyurethane, EPDM, ceramic). Furthermore, it considers the microbial colonization dynamics, which successfully correlated with the increase of energy consumption (r 2 :0.82 ± 7). The presented energy model projected the energy costs and the potential savings for the diffusers after three years in operation in different operating conditions. Whereas the most efficient diffusers provided potential costs spanning from 4900 USD/Month for a small plant (20 MGD, or 74,500 m 3 /d) up to 24,500 USD/Month for a large plant (100 MGD, or 375,000 m 3 /d), other diffusers presenting less efficiency provided spans from 18,000USD/Month for a small plant to 90,000 USD/Month for large plants. The aim of this methodology is to help utilities gain more insight into process mechanisms and design better energy efficiency strategies at existing facilities to reduce energy consumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

Integrating genomic selection into dairy cattle breeding programmes: a review.

PubMed

Bouquet, A; Juga, J

2013-05-01

Extensive genetic progress has been achieved in dairy cattle populations on many traits of economic importance because of efficient breeding programmes. Success of these programmes has relied on progeny testing of the best young males to accurately assess their genetic merit and hence their potential for breeding. Over the last few years, the integration of dense genomic information into statistical tools used to make selection decisions, commonly referred to as genomic selection, has enabled gains in predicting accuracy of breeding values for young animals without own performance. The possibility to select animals at an early stage allows defining new breeding strategies aimed at boosting genetic progress while reducing costs. The first objective of this article was to review methods used to model and optimize breeding schemes integrating genomic selection and to discuss their relative advantages and limitations. The second objective was to summarize the main results and perspectives on the use of genomic selection in practical breeding schemes, on the basis of the example of dairy cattle populations. Two main designs of breeding programmes integrating genomic selection were studied in dairy cattle. Genomic selection can be used either for pre-selecting males to be progeny tested or for selecting males to be used as active sires in the population. The first option produces moderate genetic gains without changing the structure of breeding programmes. The second option leads to large genetic gains, up to double those of conventional schemes because of a major reduction in the mean generation interval, but it requires greater changes in breeding programme structure. The literature suggests that genomic selection becomes more attractive when it is coupled with embryo transfer technologies to further increase selection intensity on the dam-to-sire pathway. The use of genomic information also offers new opportunities to improve preservation of genetic variation. However, recent simulation studies have shown that putting constraints on genomic inbreeding rates for defining optimal contributions of breeding animals could significantly reduce achievable genetic gain. Finally, the article summarizes the potential of genomic selection to include new traits in the breeding goal to meet societal demands regarding animal health and environmental efficiency in animal production.

The dependence of the growth rate and meat content of young boars on semen parameters and conception rate.

PubMed

Knecht, D; Jankowska-Mąkosa, A; Duziński, K

2017-05-01

Boars have a decisive impact on the progress in pig production, however, there is no recent information about the optimal growth parameters during the rearing period for modern breed later used in artificial insemination (AI) stations. Therefore, the objective of the research was to conduct semen parameter and conception rate analyses on the basis of growth rate and meat content assessments made during the rearing of AI boars of different genotypes. The study was carried out between 2010 and 2014 and included 184 boars in five breed combinations: 46 Polish Large White, 50 Polish Landrace, 27 Pietrain, 36 Duroc×Pietrain and 25 Hampshire×Pietrain. Boars were qualified by daily gains and meat content assessment (between 170 and 210 days of life). A total number of 38 272 ejaculates were examined (semen volume (ml), spermatozoa concentration (×106 ml-1), total number of spermatozoa (×109) and number of insemination doses from one ejaculate (n)). The fertility was determined by the conception rate (%). Semen volume, spermatozoa concentration and conception rate (P<0.01), followed by the total number of spermatozoa and insemination doses (P<0.05) were characterized by the highest variability in relation to breed of boars. The effect of daily gains was reported for spermatozoa concentration, number of insemination doses, conception rate (all P<0.01) and total number of spermatozoa (P<0.05). The peak of growth for spermatozoa concentration, total number of spermatozoa, insemination doses and conception rate was achieved for 800 to 850 g gains. Meat content affected semen volume, number of insemination doses and conception rate (P<0.05). Rearing boars while maintaining daily gains at the 800 to 850 g level and 62.5% to 65% meat content helps AI stations to increase the efficiency and economic profitability, and the number of insemination doses to increase by up to 300 doses/boar within a year. The analyses of growth parameters may help increase the efficiency and economic viability of AI stations.

A compact design for the Josephson mixer: The lumped element circuit

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

Pillet, J.-D.; Collège de France, 11 place Marcelin Berthelot, 75005 Paris; Flurin, E.

2015-06-01

We present a compact and efficient design in terms of gain, bandwidth, and dynamical range for the Josephson mixer, the superconducting circuit performing three-wave mixing at microwave frequencies. In an all lumped-element based circuit with galvanically coupled ports, we demonstrate nondegenerate amplification for microwave signals over a bandwidth up to 50 MHz for a power gain of 20 dB. The quantum efficiency of the mixer is shown to be about 70%, and its saturation power reaches −112 dBm.

Comparative Behaviour of Nitrite and Nitrate for the Protection of Rebar Corrosion

NASA Astrophysics Data System (ADS)

Ahmad, Altaf; Kumar, Anil

2017-10-01

Corrosion of rebar steel due to environmental causes has been studied through various approaches, and among the protection techniques use of inhibitors has gained encouragement. Nitrites and nitrates of sodium have gained sufficient scientific coverage. Recently, nitrites and nitrates of calcium have been verified in some studies, which, however, needs further experimentation through different angles. Simple polarization technique has been utilized in the present study to compare inhibitive efficiency of these salts of sodium and calcium, which indicate that calcium salts are more efficient.

A data mining paradigm for identifying key factors in biological processes using gene expression data.

PubMed

Li, Jin; Zheng, Le; Uchiyama, Akihiko; Bin, Lianghua; Mauro, Theodora M; Elias, Peter M; Pawelczyk, Tadeusz; Sakowicz-Burkiewicz, Monika; Trzeciak, Magdalena; Leung, Donald Y M; Morasso, Maria I; Yu, Peng

2018-06-13

A large volume of biological data is being generated for studying mechanisms of various biological processes. These precious data enable large-scale computational analyses to gain biological insights. However, it remains a challenge to mine the data efficiently for knowledge discovery. The heterogeneity of these data makes it difficult to consistently integrate them, slowing down the process of biological discovery. We introduce a data processing paradigm to identify key factors in biological processes via systematic collection of gene expression datasets, primary analysis of data, and evaluation of consistent signals. To demonstrate its effectiveness, our paradigm was applied to epidermal development and identified many genes that play a potential role in this process. Besides the known epidermal development genes, a substantial proportion of the identified genes are still not supported by gain- or loss-of-function studies, yielding many novel genes for future studies. Among them, we selected a top gene for loss-of-function experimental validation and confirmed its function in epidermal differentiation, proving the ability of this paradigm to identify new factors in biological processes. In addition, this paradigm revealed many key genes in cold-induced thermogenesis using data from cold-challenged tissues, demonstrating its generalizability. This paradigm can lead to fruitful results for studying molecular mechanisms in an era of explosive accumulation of publicly available biological data.

Implementation of an object oriented track reconstruction model into multiple LHC experiments*

NASA Astrophysics Data System (ADS)

Gaines, Irwin; Gonzalez, Saul; Qian, Sijin

2001-10-01

An Object Oriented (OO) model (Gaines et al., 1996; 1997; Gaines and Qian, 1998; 1999) for track reconstruction by the Kalman filtering method has been designed for high energy physics experiments at high luminosity hadron colliders. The model has been coded in the C++ programming language and has been successfully implemented into the OO computing environments of both the CMS (1994) and ATLAS (1994) experiments at the future Large Hadron Collider (LHC) at CERN. We shall report: how the OO model was adapted, with largely the same code, to different scenarios and serves the different reconstruction aims in different experiments (i.e. the level-2 trigger software for ATLAS and the offline software for CMS); how the OO model has been incorporated into different OO environments with a similar integration structure (demonstrating the ease of re-use of OO program); what are the OO model's performance, including execution time, memory usage, track finding efficiency and ghost rate, etc.; and additional physics performance based on use of the OO tracking model. We shall also mention the experience and lessons learned from the implementation of the OO model into the general OO software framework of the experiments. In summary, our practice shows that the OO technology really makes the software development and the integration issues straightforward and convenient; this may be particularly beneficial for the general non-computer-professional physicists.

Light Collection Efficiency in Thin Strip Plastic Scintillator for the Study of ISGMR in Unstable Nuclei

NASA Astrophysics Data System (ADS)

Shafer, Jacob

2011-10-01

The compressibility of nuclear matter (KA) is one of the constituent of the equation of state for nuclear matter which is important in the study Neutron Stars and Super Novae. The KA is proportional to the Giant Monopole Resonance (GMR) energy and is related by the equation EGMR = (h2/mr2) 1/2 *(AKA)1/2 , where ``m'' is the mass of a nucleon and ``r'' is the radius of the nucleus. The GMR in unstable nuclei is important because the KA is related to the ratio of protons to neutrons. For this reason, it is desirable to study unstable nuclei as well as stable nuclei. The study of the GMR in unstable nuclei will be done using inverse kinematics on a target of Lithium (6Li). A detector composed of two layers of thin strip scintillators and one layer of large block scintillators has been designed and constructed to give adequate energy and angular distribution over a large portion of the solid angle where decay particles from the ISGMR can be found. Attenuation of the light signal in the strip scintillators was measured using an Americium (241Am) alpha source. Gains in light collection efficiency due to various wrapping techniques were also measured. The thin strip scintillators are connected to the photomultiplier tube (PMT) via bundles of optical fiber. Losses in light calculation efficiency due to fiber bundles were measured as well. Funded by DOE and NSF-REU.

Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Gerrish, Harold P., Jr.

2003-01-01

This paper presents viewgraphs on Solar Thermal Propulsion (STP). Some of the topics include: 1) Ways to use Solar Energy for Propulsion; 2) Solar (fusion) Energy; 3) Operation in Orbit; 4) Propulsion Concepts; 5) Critical Equations; 6) Power Efficiency; 7) Major STP Projects; 8) Types of STP Engines; 9) Solar Thermal Propulsion Direct Gain Assembly; 10) Specific Impulse; 11) Thrust; 12) Temperature Distribution; 13) Pressure Loss; 14) Transient Startup; 15) Axial Heat Input; 16) Direct Gain Engine Design; 17) Direct Gain Engine Fabrication; 18) Solar Thermal Propulsion Direct Gain Components; 19) Solar Thermal Test Facility; and 20) Checkout Results.

Technical Note: Modification of the standard gain correction algorithm to compensate for the number of used reference flat frames in detector performance studies

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

Konstantinidis, Anastasios C.; Olivo, Alessandro; Speller, Robert D.

2011-12-15

Purpose: The x-ray performance evaluation of digital x-ray detectors is based on the calculation of the modulation transfer function (MTF), the noise power spectrum (NPS), and the resultant detective quantum efficiency (DQE). The flat images used for the extraction of the NPS should not contain any fixed pattern noise (FPN) to avoid contamination from nonstochastic processes. The ''gold standard'' method used for the reduction of the FPN (i.e., the different gain between pixels) in linear x-ray detectors is based on normalization with an average reference flat-field. However, the noise in the corrected image depends on the number of flat framesmore » used for the average flat image. The aim of this study is to modify the standard gain correction algorithm to make it independent on the used reference flat frames. Methods: Many publications suggest the use of 10-16 reference flat frames, while other studies use higher numbers (e.g., 48 frames) to reduce the propagated noise from the average flat image. This study quantifies experimentally the effect of the number of used reference flat frames on the NPS and DQE values and appropriately modifies the gain correction algorithm to compensate for this effect. Results: It is shown that using the suggested gain correction algorithm a minimum number of reference flat frames (i.e., down to one frame) can be used to eliminate the FPN from the raw flat image. This saves computer memory and time during the x-ray performance evaluation. Conclusions: The authors show that the method presented in the study (a) leads to the maximum DQE value that one would have by using the conventional method and very large number of frames and (b) has been compared to an independent gain correction method based on the subtraction of flat-field images, leading to identical DQE values. They believe this provides robust validation of the proposed method.« less

Förster-Induced Energy Transfer in Functionalized Graphene

PubMed Central

2014-01-01

Carbon nanostructures are ideal substrates for functionalization with molecules since they consist of a single atomic layer giving rise to an extraordinary sensitivity to changes in their surrounding. The functionalization opens a new research field of hybrid nanostructures with tailored properties. Here, we present a microscopic view on the substrate–molecule interaction in the exemplary hybrid material consisting of graphene functionalized with perylene molecules. First experiments on similar systems have been recently realized illustrating an extremely efficient transfer of excitation energy from adsorbed molecules to the carbon substrate, a process with a large application potential for high-efficiency photovoltaic devices and biomedical imaging and sensing. So far, there has been no microscopically founded explanation for the observed energy transfer. Based on first-principle calculations, we have explicitly investigated the different transfer mechanisms revealing the crucial importance of Förster coupling. Due to the efficient Coulomb interaction in graphene, we obtain strong Förster rates in the range of 1/fs. We investigate its dependence on the substrate–molecule distance R and describe the impact of the momentum transfer q for an efficient energy transfer. Furthermore, we find that the Dexter transfer mechanism is negligibly small due to the vanishing overlap between the involved strongly localized orbital functions. The gained insights are applicable to a variety of carbon-based hybrid nanostructures. PMID:24808936

Complexity control algorithm based on adaptive mode selection for interframe coding in high efficiency video coding

NASA Astrophysics Data System (ADS)

Chen, Gang; Yang, Bing; Zhang, Xiaoyun; Gao, Zhiyong

2017-07-01

The latest high efficiency video coding (HEVC) standard significantly increases the encoding complexity for improving its coding efficiency. Due to the limited computational capability of handheld devices, complexity constrained video coding has drawn great attention in recent years. A complexity control algorithm based on adaptive mode selection is proposed for interframe coding in HEVC. Considering the direct proportionality between encoding time and computational complexity, the computational complexity is measured in terms of encoding time. First, complexity is mapped to a target in terms of prediction modes. Then, an adaptive mode selection algorithm is proposed for the mode decision process. Specifically, the optimal mode combination scheme that is chosen through offline statistics is developed at low complexity. If the complexity budget has not been used up, an adaptive mode sorting method is employed to further improve coding efficiency. The experimental results show that the proposed algorithm achieves a very large complexity control range (as low as 10%) for the HEVC encoder while maintaining good rate-distortion performance. For the lowdelayP condition, compared with the direct resource allocation method and the state-of-the-art method, an average gain of 0.63 and 0.17 dB in BDPSNR is observed for 18 sequences when the target complexity is around 40%.

Stability analysis via the concept of Lyapunov exponents: a case study in optimal controlled biped standing

NASA Astrophysics Data System (ADS)

Sun, Yuming; Wu, Christine Qiong

2012-12-01

Balancing control is important for biped standing. In spite of large efforts, it is very difficult to design balancing control strategies satisfying three requirements simultaneously: maintaining postural stability, improving energy efficiency and satisfying the constraints between the biped feet and the ground. In this article, a proportional-derivative (PD) controller is proposed for a standing biped, which is simplified as a two-link inverted pendulum with one additional rigid foot-link. The genetic algorithm (GA) is used to search for the control gain meeting all three requirements. The stability analysis of such a deterministic biped control system is carried out using the concept of Lyapunov exponents (LEs), based on which, the system stability, where the disturbance comes from the initial states, and the structural stability, where the disturbance comes from the PD gains, are examined quantitively in terms of stability region. This article contributes to the biped balancing control, more significantly, the method shown in the studied case of biped provides a general framework of systematic stability analysis for certain deterministic nonlinear dynamical systems.

Series resonant converter with auxiliary winding turns: analysis, design and implementation

NASA Astrophysics Data System (ADS)

Lin, Bor-Ren

2018-05-01

Conventional series resonant converters have researched and applied for high-efficiency power units due to the benefit of its low switching losses. The main problems of series resonant converters are wide frequency variation and high circulating current. Thus, resonant converter is limited at narrow input voltage range and large input capacitor is normally adopted in commercial power units to provide the minimum hold-up time requirement when AC power is off. To overcome these problems, the resonant converter with auxiliary secondary windings are presented in this paper to achieve high voltage gain at low input voltage case such as hold-up time duration when utility power is off. Since the high voltage gain is used at low input voltage cased, the frequency variation of the proposed converter compared to the conventional resonant converter is reduced. Compared to conventional resonant converter, the hold-up time in the proposed converter is more than 40ms. The larger magnetising inductance of transformer is used to reduce the circulating current losses. Finally, a laboratory prototype is constructed and experiments are provided to verify the converter performance.

Biotransformation of lignocellulosic materials into value-added products-A review.

PubMed

Bilal, Muhammad; Asgher, Muhammad; Iqbal, Hafiz M N; Hu, Hongbo; Zhang, Xuehong

2017-05-01

In the past decade, with the key biotechnological advancements, lignocellulosic materials have gained a particular importance. In serious consideration of global economic, environmental and energy issues, research scientists have been re-directing their interests in (re)-valorizing naturally occurring lignocellulosic-based materials. In this context, lignin-modifying enzymes (LMEs) have gained considerable attention in numerous industrial and biotechnological processes. However, their lower catalytic efficiencies and operational stabilities limit their practical and multipurpose applications in various sectors. Therefore, to expand the range of natural industrial biocatalysts e.g. LMEs, significant progress related to the enzyme biotechnology has appeared. Owing to the abundant lignocellulose availability along with LMEs in combination with the scientific advances in the biotechnological era, solid-phase biocatalysts can be economically tailored on a large scale. This review article outlines first briefly on the lignocellulose materials as a potential source for biotransformation into value-added products including composites, fine chemicals, nutraceutical, delignification, and enzymes. Comprehensive information is also given on the purification and characterization of LMEs to present their potential for the industrial and biotechnological sector. Copyright © 2017 Elsevier B.V. All rights reserved.

76 FR 35295 - Delivering an Efficient, Effective, and Accountable Government

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-16

... reinforce the performance and management reform gains my Administration has achieved, it is hereby ordered... and leaner Government, my Administration will reinforce the performance and management reform gains... (PMC), shall work with the PMC to support agencies' performance and management reform and cost- cutting...

How much is new information worth? Evaluating the financial benefit of resolving management uncertainty

USGS Publications Warehouse

Maxwell, Sean L.; Rhodes, Jonathan R.; Runge, Michael C.; Possingham, Hugh P.; Ng, Chooi Fei; McDonald Madden, Eve

2015-01-01

Conservation decision-makers face a trade-off between spending limited funds on direct management action, or gaining new information in an attempt to improve management performance in the future. Value-of-information analysis can help to resolve this trade-off by evaluating how much management performance could improve if new information was gained. Value-of-information analysis has been used extensively in other disciplines, but there are only a few examples where it has informed conservation planning, none of which have used it to evaluate the financial value of gaining new information. We address this gap by applying value-of-information analysis to the management of a declining koala Phascolarctos cinereuspopulation. Decision-makers responsible for managing this population face uncertainty about survival and fecundity rates, and how habitat cover affects mortality threats. The value of gaining new information about these uncertainties was calculated using a deterministic matrix model of the koala population to find the expected population growth rate if koala mortality threats were optimally managed under alternative model hypotheses, which represented the uncertainties faced by koala managers. Gaining new information about survival and fecundity rates and the effect of habitat cover on mortality threats will do little to improve koala management. Across a range of management budgets, no more than 1·7% of the budget should be spent on resolving these uncertainties. The value of information was low because optimal management decisions were not sensitive to the uncertainties we considered. Decisions were instead driven by a substantial difference in the cost efficiency of management actions. The value of information was up to forty times higher when the cost efficiencies of different koala management actions were similar. Synthesis and applications. This study evaluates the ecological and financial benefits of gaining new information to inform a conservation problem. We also theoretically demonstrate that the value of reducing uncertainty is highest when it is not clear which management action is the most cost efficient. This study will help expand the use of value-of-information analyses in conservation by providing a cost efficiency metric by which to evaluate research or monitoring.

Multiyear, Multi-Instructor Evaluation of a Large-Class Interactive-Engagement Curriculum

ERIC Educational Resources Information Center

Cahill, Michael J.; Hynes, K. Mairin; Trousil, Rebecca; Brooks, Lisa A.; McDaniel, Mark A.; Repice, Michelle; Zhao, Jiuqing; Frey, Regina F.

2014-01-01

Interactive-engagement (IE) techniques consistently enhance conceptual learning gains relative to traditional-lecture courses, but attitudinal gains typically emerge only in small, inquiry-based curricula. The current study evaluated whether a "scalable IE" curriculum--a curriculum used in a large course (~130 students per section) and…

DSN 70-meter antenna X- and S-band calibration. Part 1: Gain measurements

NASA Technical Reports Server (NTRS)

Richter, P. H.; Slobin, S. D.

1989-01-01

Aperture efficiency measurements made during 1988 on the three 70-m stations (DSS-14, DSS-43, and DSS-63) at X-band (8420 MHz) and S-band (2295 MHz) have been analyzed and reduced to yield best estimates of antenna gain versus elevation. The analysis has been carried out by fitting the gain data to a theoretical expression based on the Ruze formula. Newly derived flux density and source-size correction factors for the natural radio calibration sources used in the measurements have been used in the reduction of the data. Peak gains measured at the three stations were 74.18 (plus or minus 0.10) dBi at X-band, and 63.34 (plus or minus 0.03) dBi at S-band, with corresponding peak aperture efficiencies of 0.687 (plus or minus 0.015) and 0.762 (plus or minus 0.006), respectively. The values quoted assume no atmosphere is present, and the estimated absolute accuracy of the gain measurements is approximately plus or minus 0.2 dB at X-band and plus or minus 0.1 dB at S-band (1-sigma values).

Maximizing output power of a low-gain laser system.

PubMed

Carroll, D L; Sentman, L H

1993-07-20

Rigrod theory was used to model outcoupled power from a low-gain laser with good accuracy. For a low-gain overtone cw HF chemical laser, Rigrod theory shows that a higher medium saturation yields a higher overall overtone efficiency, but does not necessarily yield a higher measurable power (power in the bucket). For low-absorption-scattering loss overtone mirrors and a 5% penalty in outcoupled power, the intracavity flux and hence the mirror loading may be reduced by more than a factor of 2 when the gain length is long enough to saturate the medium well. For the University of Illinois at Urbana-Champaign overtone laser that has an extensive database with well-characterized mirrors for which the Rigrod parameters g(0) and I(sat) were firmly established, the accuracy to which the reflectivities of high-reflectivity overtone mirrors can be deduced by using measured mirror transmissivities, measured outcoupled power, and Rigrod theory is approximatly ±0.07%. This method of accurately deducing mirror reflectivities may be applicable to other low-gain laser systems that use high-reflectivity mirrors at different wavelengths. The maximum overtone efficiency is estimated to be approximately 80%-100%.

Gain and temperature in a slit nozzle supersonic chemical oxygen-iodine laser with transonic and supersonic injection of iodine

NASA Astrophysics Data System (ADS)

Rosenwaks, Salman; Barmashenko, Boris D.; Bruins, Esther; Furman, Dov; Rybalkin, Victor; Katz, Arje

2002-05-01

Spatial distributions of the gain and temperament across the flow were studied for transonic and supersonic schemes of the iodine injection in a slit nozzle supersonic chemical oxygen-iodine laser as a function of the iodine and secondary nitrogen flow rate, jet penetration parameter and gas pumping rate. The mixing efficiency for supersonic injection of iodine is found to be much larger than for transonic injection, the maximum values of the gain being approximately 0.65 percent/cm for both injection schemes. Measurements of the gain distribution as a function of the iodine molar flow rate nI2 were carried out. For transonic injection the optimal value of nI2 at the flow centerline is smaller than that at the off axis location. The temperature is distributed homogeneously across the flow, increasing only in the narrow boundary layers near the walls. Opening a leak downstream of the cavity in order to decease the Mach number results in a decrease of the gain and increase of the temperature. The mixing efficiency in this case is much larger than for closed leak.

Fixing the system? The experience of service users of the quasi-market in disability services in Australia.

PubMed

Spall, Pam; McDonald, Catherine; Zetlin, Di

2005-01-01

A qualitative study involving semi-structured interviews with 31 people with disabilities and 32 carers in the state of Queensland, Australia, found that their experience of supportive service delivery had not improved despite reforms of the service delivery system driven by a version of the quasi-market model. Instead of delivering increased consumer choice and improved efficiency in service delivery, service users experienced inadequate service supply, service cutbacks, and an increased emphasis on cost subsidisation and assessment processes. Additionally, few consumers felt that individualised funding arrangements had personally delivered the benefits which the quasi-market model and associated policy paradigm had indicated that they should receive. For many consumers, the notion of consumer 'choice' around service provision was fictitious and they felt that any efficiency gains were at the agency level, largely at the consumers' cost. It is concluded that there appears to be no particular benefit to service users of quasi-market reforms, particularly in policy contexts where service delivery systems are historically under-funded.

Method for computationally efficient design of dielectric laser accelerator structures

DOE PAGES

Hughes, Tyler; Veronis, Georgios; Wootton, Kent P.; ...

2017-06-22

Here, dielectric microstructures have generated much interest in recent years as a means of accelerating charged particles when powered by solid state lasers. The acceleration gradient (or particle energy gain per unit length) is an important figure of merit. To design structures with high acceleration gradients, we explore the adjoint variable method, a highly efficient technique used to compute the sensitivity of an objective with respect to a large number of parameters. With this formalism, the sensitivity of the acceleration gradient of a dielectric structure with respect to its entire spatial permittivity distribution is calculated by the use of onlymore » two full-field electromagnetic simulations, the original and ‘adjoint’. The adjoint simulation corresponds physically to the reciprocal situation of a point charge moving through the accelerator gap and radiating. Using this formalism, we perform numerical optimizations aimed at maximizing acceleration gradients, which generate fabricable structures of greatly improved performance in comparison to previously examined geometries.« less

Guiding of relativistic electron beams in dense matter by laser-driven magnetostatic fields.

PubMed

Bailly-Grandvaux, M; Santos, J J; Bellei, C; Forestier-Colleoni, P; Fujioka, S; Giuffrida, L; Honrubia, J J; Batani, D; Bouillaud, R; Chevrot, M; Cross, J E; Crowston, R; Dorard, S; Dubois, J-L; Ehret, M; Gregori, G; Hulin, S; Kojima, S; Loyez, E; Marquès, J-R; Morace, A; Nicolaï, Ph; Roth, M; Sakata, S; Schaumann, G; Serres, F; Servel, J; Tikhonchuk, V T; Woolsey, N; Zhang, Z

2018-01-09

Intense lasers interacting with dense targets accelerate relativistic electron beams, which transport part of the laser energy into the target depth. However, the overall laser-to-target energy coupling efficiency is impaired by the large divergence of the electron beam, intrinsic to the laser-plasma interaction. Here we demonstrate that an efficient guiding of MeV electrons with about 30 MA current in solid matter is obtained by imposing a laser-driven longitudinal magnetostatic field of 600 T. In the magnetized conditions the transported energy density and the peak background electron temperature at the 60-μm-thick target's rear surface rise by about a factor of five, as unfolded from benchmarked simulations. Such an improvement of energy-density flux through dense matter paves the ground for advances in laser-driven intense sources of energetic particles and radiation, driving matter to extreme temperatures, reaching states relevant for planetary or stellar science as yet inaccessible at the laboratory scale and achieving high-gain laser-driven thermonuclear fusion.

Dual-Vivaldi wideband nanoantenna with high radiation efficiency over the infrared frequency band.

PubMed

Iluz, Zeev; Boag, Amir

2011-08-01

A dual-Vivaldi nanoantenna is proposed to demonstrate the possibility of wideband operation at IR frequencies. The antenna geometry design is guided by the material properties of metals at IR frequencies. According to our numerical results, this nanoantenna has both high radiation efficiency and good impedance-matching properties over a wide frequency band (more than 122%) in the IR frequency band. The design is based on the well-known Vivaldi antenna placed on quartz substrate but operating as a pair instead of a single element. Such a pair of Vivaldi antennas oriented in opposite directions produces the main lobe in the broadside direction (normal to the axes of the antennas) rather than the usual peak gain along the axis (end fire) of a single Vivaldi antenna. The dual-Vivaldi nanoantenna is easy to fabricate in a conventional electron-beam lithography process, and it provides a large number of degrees of freedom, facilitating design for ultra-wideband operation. © 2011 Optical Society of America

Travelling-wave resonant four-wave mixing breaks the limits of cavity-enhanced all-optical wavelength conversion.

PubMed

Morichetti, Francesco; Canciamilla, Antonio; Ferrari, Carlo; Samarelli, Antonio; Sorel, Marc; Melloni, Andrea

2011-01-01

Wave mixing inside optical resonators, while experiencing a large enhancement of the nonlinear interaction efficiency, suffers from strong bandwidth constraints, preventing its practical exploitation for processing broad-band signals. Here we show that such limits are overcome by the new concept of travelling-wave resonant four-wave mixing (FWM). This approach combines the efficiency enhancement provided by resonant propagation with a wide-band conversion process. Compared with conventional FWM in bare waveguides, it exhibits higher robustness against chromatic dispersion and propagation loss, while preserving transparency to modulation formats. Travelling-wave resonant FWM has been demonstrated in silicon-coupled ring resonators and was exploited to realize a 630-μm-long wavelength converter operating over a wavelength range wider than 60 nm and with 28-dB gain with respect to a bare waveguide of the same physical length. Full compatibility of the travelling-wave resonant FWM with optical signal processing applications has been demonstrated through signal retiming and reshaping at 10 Gb s(-1).

Infrared photodetectors based on graphene van der Waals heterostructures

NASA Astrophysics Data System (ADS)

Ryzhii, V.; Ryzhii, M.; Svintsov, D.; Leiman, V.; Mitin, V.; Shur, M. S.; Otsuji, T.

2017-08-01

We propose and evaluate the graphene layer (GL) infrared photodetectors (GLIPs) based on the van der Waals (vdW) heterostructures with the radiation absorbing GLs. The operation of the GLIPs is associated with the electron photoexcitation from the GL valence band to the continuum states above the inter-GL barriers (either via tunneling or direct transitions to the continuum states). Using the developed device model, we calculate the photodetector characteristics as functions of the GL-vdW heterostructure parameters. We show that due to a relatively large efficiency of the electron photoexcitation and low capture efficiency of the electrons propagating over the barriers in the inter-GL layers, GLIPs should exhibit the elevated photoelectric gain and detector responsivity as well as relatively high detectivity. The possibility of high-speed operation, high conductivity, transparency of the GLIP contact layers, and the sensitivity to normally incident IR radiation provides additional potential advantages in comparison with other IR photodetectors. In particular, the proposed GLIPs can compete with unitravelling-carrier photodetectors.

Error control techniques for satellite and space communications

NASA Technical Reports Server (NTRS)

Costello, Daniel J., Jr.

1991-01-01

Shannon's capacity bound shows that coding can achieve large reductions in the required signal to noise ratio per information bit (E sub b/N sub 0 where E sub b is the energy per bit and (N sub 0)/2 is the double sided noise density) in comparison to uncoded schemes. For bandwidth efficiencies of 2 bit/sym or greater, these improvements were obtained through the use of Trellis Coded Modulation and Block Coded Modulation. A method of obtaining these high efficiencies using multidimensional Multiple Phase Shift Keying (MPSK) and Quadrature Amplitude Modulation (QAM) signal sets with trellis coding is described. These schemes have advantages in decoding speed, phase transparency, and coding gain in comparison to other trellis coding schemes. Finally, a general parity check equation for rotationally invariant trellis codes is introduced from which non-linear codes for two dimensional MPSK and QAM signal sets are found. These codes are fully transparent to all rotations of the signal set.

Travelling-wave resonant four-wave mixing breaks the limits of cavity-enhanced all-optical wavelength conversion

PubMed Central

Morichetti, Francesco; Canciamilla, Antonio; Ferrari, Carlo; Samarelli, Antonio; Sorel, Marc; Melloni, Andrea

2011-01-01

Wave mixing inside optical resonators, while experiencing a large enhancement of the nonlinear interaction efficiency, suffers from strong bandwidth constraints, preventing its practical exploitation for processing broad-band signals. Here we show that such limits are overcome by the new concept of travelling-wave resonant four-wave mixing (FWM). This approach combines the efficiency enhancement provided by resonant propagation with a wide-band conversion process. Compared with conventional FWM in bare waveguides, it exhibits higher robustness against chromatic dispersion and propagation loss, while preserving transparency to modulation formats. Travelling-wave resonant FWM has been demonstrated in silicon-coupled ring resonators and was exploited to realize a 630-μm-long wavelength converter operating over a wavelength range wider than 60 nm and with 28-dB gain with respect to a bare waveguide of the same physical length. Full compatibility of the travelling-wave resonant FWM with optical signal processing applications has been demonstrated through signal retiming and reshaping at 10 Gb s−1 PMID:21540838

The CHROMA focal plane array: a large-format, low-noise detector optimized for imaging spectroscopy

NASA Astrophysics Data System (ADS)

Demers, Richard T.; Bailey, Robert; Beletic, James W.; Bernd, Steve; Bhargava, Sidharth; Herring, Jason; Kobrin, Paul; Lee, Donald; Pan, Jianmei; Petersen, Anders; Piquette, Eric; Starr, Brian; Yamamoto, Matthew; Zandian, Majid

2013-09-01

The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced Focal Plane Array (FPA) designed for visible-infrared imaging spectroscopy. Using Teledyne's latest substrateremoved HgCdTe detector, the CHROMA FPA has very low dark current, low readout noise and high, stable quantum efficiency from the deep blue (390nm) to the cutoff wavelength. CHROMA has a pixel pitch of 30 microns and is available in array formats ranging from 320×480 to 1600×480 pixels. Users generally disperse spectra over the 480 pixel-length columns and image spatially over the n×160 pixellength rows, where n=2, 4, 8, 10. The CHROMA Readout Integrated Circuit (ROIC) has Correlated Double Sampling (CDS) in pixel and generates its own internal bias signals and clocks. This paper presents the measured performance of the CHROMA FPA with 2.5 micron cutoff wavelength including the characterization of noise versus pixel gain, power dissipation and quantum efficiency.

Lasing in silicon–organic hybrid waveguides

PubMed Central

Korn, Dietmar; Lauermann, Matthias; Koeber, Sebastian; Appel, Patrick; Alloatti, Luca; Palmer, Robert; Dumon, Pieter; Freude, Wolfgang; Leuthold, Juerg; Koos, Christian

2016-01-01

Silicon photonics enables large-scale photonic–electronic integration by leveraging highly developed fabrication processes from the microelectronics industry. However, while a rich portfolio of devices has already been demonstrated on the silicon platform, on-chip light sources still remain a key challenge since the indirect bandgap of the material inhibits efficient photon emission and thus impedes lasing. Here we demonstrate a class of infrared lasers that can be fabricated on the silicon-on-insulator (SOI) integration platform. The lasers are based on the silicon–organic hybrid (SOH) integration concept and combine nanophotonic SOI waveguides with dye-doped organic cladding materials that provide optical gain. We demonstrate pulsed room-temperature lasing with on-chip peak output powers of up to 1.1 W at a wavelength of 1,310 nm. The SOH approach enables efficient mass-production of silicon photonic light sources emitting in the near infrared and offers the possibility of tuning the emission wavelength over a wide range by proper choice of dye materials and resonator geometry. PMID:26949229

Do pre- and post-copulatory sexually selected traits covary in large herbivores?

PubMed Central

2014-01-01

Background In most species, males compete to gain both matings (via pre-copulatory competition) and fertilizations (via post-copulatory competition) to maximize their reproductive success. However, the quantity of resources devoted to sexual traits is finite, and so males are predicted to balance their investment between pre- and post-copulatory expenditure depending on the expected pay-offs that should vary according to mating tactics. In Artiodactyla species, males can invest in weapons such as horns or antlers to increase their mating gains or in testes mass/sperm dimensions to increase their fertilization efficiency. Moreover, it has been suggested that in these species, males with territory defence mating tactic might preferentially increase their investment in post-copulatory traits to increase their fertilization efficiency whereas males with female defence mating tactic might increase their investment in pre-copulatory sexually selected traits to prevent other males from copulating with females. In this study, we thus test the prediction that male’s weapon length (pre-copulatory trait) covaries negatively with relative testes size and/or sperm dimensions (post-copulatory traits) across Artiodactyla using a phylogenetically controlled framework. Results Surprisingly no association between weapon length and testes mass is found but a negative association between weapon length and sperm length is evidenced. In addition, neither pre- nor post-copulatory traits were found to be affected by male mating tactics. Conclusions We propose several hypotheses that could explain why male ungulates may not balance their reproductive investment between pre- and post-copulatory traits. PMID:24716470

AN EFFICIENT, COMPACT, AND VERSATILE FIBER DOUBLE SCRAMBLER FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

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

Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath

2015-06-10

We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index n ∼ 2 ball lens that exchanges the near and far fields between two fibers. When used in conjunction with octagonal fibers, this device yields very high scrambling gains (SGs) and greatly desensitizes the fiber output from any input illumination variations, thereby stabilizing the instrument profile of the spectrograph and improving the Doppler measurement precision. The system is also highly insensitive to input pupil variations, isolating the spectrograph from telescope illumination variationsmore » and seeing changes. By selecting the appropriate glass and lens diameter the highest efficiency is achieved when the fibers are practically in contact with the lens surface, greatly simplifying the alignment process when compared to classical double-scrambler systems. This prototype double-scrambler has demonstrated significant performance gains over previous systems, achieving SGs in excess of 10,000 with a throughput of ∼87% using uncoated Polymicro octagonal fibers. Adding a circular fiber to the fiber train further increases the SG to >20,000, limited by laboratory measurement error. While this fiber system is designed for the Habitable-zone Planet Finder spectrograph, it is more generally applicable to other instruments in the visible and near-infrared. Given the simplicity and low cost, this fiber scrambler could also easily be multiplexed for large multi-object instruments.« less

Device model for pixelless infrared image up-converters based on polycrystalline graphene heterostructures

NASA Astrophysics Data System (ADS)

Ryzhii, V.; Shur, M. S.; Ryzhii, M.; Karasik, V. E.; Otsuji, T.

2018-01-01

We developed a device model for pixelless converters of far/mid-infrared radiation (FIR/MIR) images into near-infrared/visible (NIR/VIR) images. These converters use polycrystalline graphene layers (PGLs) immersed in the van der Waals materials integrated with a light emitting diode (LED). The PGL serves as an element of the PGL infrared photodetector (PGLIP) sensitive to the incoming FIR/MIR due to the interband absorption. The spatially non-uniform photocurrent generated in the PGLIP repeats (mimics) the non-uniform distribution (image) created by the incident FIR/MIR. The injection of the nonuniform photocurrent into the LED active layer results in the nonuniform NIR/VIR image reproducing the FIR/MIR image. The PGL and the entire layer structure are not deliberately partitioned into pixels. We analyze the characteristics of such pixelless PGLIP-LED up-converters and show that their image contrast transfer function and the up-conversion efficiency depend on the PGL lateral resistivity. The up-converter exhibits high photoconductive gain and conversion efficiency when the lateral resistivity is sufficiently high. Several teams have successfully demonstrated the large area PGLs with the resistivities varying in a wide range. Such layers can be used in the pixelless PGLIP-LED image up-converters. The PGLIP-LED image up-converters can substantially surpass the image up-converters based on the quantum-well infrared photodetector integrated with the LED. These advantages are due to the use of the interband FIR/NIR absorption and a high photoconductive gain in the GLIPs.

Highly efficient white OLEDs for lighting applications

NASA Astrophysics Data System (ADS)

Murano, Sven; Burghart, Markus; Birnstock, Jan; Wellmann, Philipp; Vehse, Martin; Werner, Ansgar; Canzler, Tobias; Stübinger, Thomas; He, Gufeng; Pfeiffer, Martin; Boerner, Herbert

2005-10-01

The use of organic light-emitting diodes (OLEDs) for large area general lighting purposes is gaining increasing interest during the recent years. Especially small molecule based OLEDs have already shown their potential for future applications. For white light emission OLEDs, power efficiencies exceeding that of incandescent bulbs could already be demonstrated, however additional improvements are needed to further mature the technology allowing for commercial applications as general purpose illuminating sources. Ultimately the efficiencies of fluorescent tubes should be reached or even excelled, a goal which could already be achieved in the past for green OLEDs.1 In this publication the authors will present highly efficient white OLEDs based on an intentional doping of the charge carrier transport layers and the usage of different state of the art emission principles. This presentation will compare white PIN-OLEDs based on phosphorescent emitters, fluorescent emitters and stacked OLEDs. It will be demonstrated that the reduction of the operating voltage by the use of intentionally doped transport layers leads to very high power efficiencies for white OLEDs, demonstrating power efficiencies of well above 20 lm/W @ 1000 cd/m2. The color rendering properties of the emitted light is very high and CRIs between 85 and 95 are achieved, therefore the requirements for standard applications in the field of lighting applications could be clearly fulfilled. The color coordinates of the light emission can be tuned within a wide range through the implementation of minor structural changes.

Cosensitization of D-A-π-A quinoxaline organic dye: efficiently filling the absorption valley with high photovoltaic efficiency.

PubMed

Pei, Kai; Wu, Yongzhen; Li, Hui; Geng, Zhiyuan; Tian, He; Zhu, Wei-Hong

2015-03-11

In the efficient cosensitization, the pure organic sensitizers with high molecular extinction coefficients and long wavelength response are highly preferable since the dye loading amount for each dye in cosensitization is decreased with respect to single dye sensitization. A D-A-π-A featured quinoxaline organic sensitizer IQ21 is specifically designed. The high conjugation building block of 4H-cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) is introduced as the π bridge, instead of the traditional thiophene unit, especially in realizing high molecular extinction coefficients (up to 66 600 M(-1) cm(-1)) and extending the light response wavelength. With respect to the reference dye IQ4, the slightly lower efficiency of IQ21 (9.03%) arises from the decrease of VOC, which offsets the gain in JSC. While cosensitized with a smaller D-π-A dye S2, the efficiency in IQ21 is further improved to 10.41% (JSC = 19.8 mA cm(-2), VOC = 731 mV, FF = 0.72). The large improvement in efficiency is attributed to the well-matched molecular structures and loading amounts of both dyes in the cosensitization system. We also demonstrated that coabsorbent dye S2 can distinctly compensate the inherent drawbacks of IQ21, not only enhancing the response intensity of IPCE, making up the absorption defects around low wavelength region of IPCE, but also repressing the charge recombination rate to some extent.

Achieving Energy Efficiency Through Real-Time Feedback

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

Nesse, Ronald J.

2011-09-01

Through the careful implementation of simple behavior change measures, opportunities exist to achieve strategic gains, including greater operational efficiencies, energy cost savings, greater tenant health and ensuing productivity and an improved brand value through sustainability messaging and achievement.

It is more efficient to type: innovative self-registration and appointment self-arrival system improves the patient reception process.

PubMed

Knight, Vickie; Guy, Rebecca J; Handan, Wand; Lu, Heng; McNulty, Anna

2014-06-01

In 2010, we introduced an express sexually transmitted infection/HIV testing service at a large metropolitan sexual health clinic, which significantly increased clinical service capacity. However, it also increased reception staff workload and caused backlogs of patients waiting to register or check in for appointments. We therefore implemented a new electronic self-registration and appointment self-arrival system in March 2012 to increase administrative efficiency and reduce waiting time for patients. We compared the median processing time overall and for each step of the registration and arrival process as well as the completeness of patient contact information recorded, in a 1-week period before and after the redesign of the registration system. χ2 Test and rank sum tests were used. Before the redesign, the median processing time was 8.33 minutes (interquartile range [IQR], 6.82-15.43), decreasing by 30% to 5.83 minutes (IQR, 4.75-7.42) when the new electronic self-registration and appointment self-arrival system was introduced (P < 0.001). The largest gain in efficiency was in the time taken to prepare the medical record for the clinician, reducing from a median of 5.31 minutes (IQR, 4.02-8.29) to 0.57 minutes (IQR, 0.38-1) in the 2 periods. Before implementation, 20% of patients provided a postal address and 31% an e-mail address, increasing to 60% and 70% post redesign, respectively (P < 0.001). Our evaluation shows that an electronic patient self-registration and appointment self-arrival system can improve clinic efficiency and save patient time. Systems like this one could be used by any outpatient service with large patient volumes as an integrated part of the electronic patient management system or as a standalone feature.

Stream Kriging: Incremental and recursive ordinary Kriging over spatiotemporal data streams

NASA Astrophysics Data System (ADS)

Zhong, Xu; Kealy, Allison; Duckham, Matt

2016-05-01

Ordinary Kriging is widely used for geospatial interpolation and estimation. Due to the O (n3) time complexity of solving the system of linear equations, ordinary Kriging for a large set of source points is computationally intensive. Conducting real-time Kriging interpolation over continuously varying spatiotemporal data streams can therefore be especially challenging. This paper develops and tests two new strategies for improving the performance of an ordinary Kriging interpolator adapted to a stream-processing environment. These strategies rely on the expectation that, over time, source data points will frequently refer to the same spatial locations (for example, where static sensor nodes are generating repeated observations of a dynamic field). First, an incremental strategy improves efficiency in cases where a relatively small proportion of previously processed spatial locations are absent from the source points at any given iteration. Second, a recursive strategy improves efficiency in cases where there is substantial set overlap between the sets of spatial locations of source points at the current and previous iterations. These two strategies are evaluated in terms of their computational efficiency in comparison to ordinary Kriging algorithm. The results show that these two strategies can reduce the time taken to perform the interpolation by up to 90%, and approach average-case time complexity of O (n2) when most but not all source points refer to the same locations over time. By combining the approaches developed in this paper with existing heuristic ordinary Kriging algorithms, the conclusions indicate how further efficiency gains could potentially be accrued. The work ultimately contributes to the development of online ordinary Kriging interpolation algorithms, capable of real-time spatial interpolation with large streaming data sets.

Theoretical parametric study of the relative advantages of winglets and wing-tip extensions

NASA Technical Reports Server (NTRS)

Heyson, H. H.; Riebe, G. D.; Fulton, C. L.

1977-01-01

It was found that for identical increases in bending moment, a winglet provides a greater gain in induced efficiency than a tip extension. Winglet toe-in angle allows design trades between efficiency and root moment. A winglet showed the greatest benefit when the wing loads were heavy near the tip. Washout diminished the benefit of either tip modification, and the gain in induced efficiency became a function of lift coefficient; heavy wing loadings obtained the greatest benefit from a winglet, and low speed performance was enhanced even more than cruise performance. Both induced efficiency and bending moment increased with winglet length and outward cant. The benefit of a winglet relative to a tip extension was greatest for a nearly vertical winglet. Root bending moment was proportional to the minimum weight of bending material required in the wing; it is a valid index of the impact of tip modifications on a new wing design.

Theoretical Parametric Study of the Relative Advantages of Winglets and Wing-Tip Extensions

NASA Technical Reports Server (NTRS)

Heyson, H. H.; Riebe, G. D.; Fulton, C. L.

1977-01-01

For identical increases in bending moment, a winglet provides a greater gain in induced efficiency than tip extension. Winglet toe angle allows design trades between efficiency and root moment. A winglet shows the greatest benefit when the wing loads are heavy near the tip. Washout diminishes the benefit of either tip modification, and the gain in induced efficiency becomes a function of lift coefficient; thus, heavy wing loadings obtain the greatest benefit from a winglet, and low-speed performance is enhanced even more than cruise performance. Both induced efficiency and bending moment increase with winglet length and outward cant. The benefit of a winglet relative to a tip extension is greatest for a nearly vertical winglet. Root bending moment is proportional to the minimum weight of bending material required in the wing; thus, it is a valid index of the impact of tip modifications on a new wing design.

Evaluation of wheat-based thin stillage as a water source for growing and finishing beef cattle.

PubMed

Fisher, D J; McKinnon, J J; Mustafa, A F; Christensen, D A; McCartney, D

1999-10-01

Two trials were conducted to evaluate the nutritional value of wheat-based thin stillage as a water source for cattle. In Trial 1, 20 large-framed steers were fed a basal diet based primarily on barley grain and barley silage, with ad libitum access to water or thin stillage at one of three DM concentrations (2, 4, and 6.7%) in a completely randomized design. The trial consisted of a 70-d growing period and a finishing phase. In Trial 2, total-tract nutrient digestibility coefficients of the basal diet and water treatments fed in the growing period were determined in a randomized complete block design using 12 medium-framed steers. The results showed that when only DMI from the basal diet was considered, there was a linear reduction (P<.01) in DMI and a linear improvement (P<.01) in the gain:feed ratio with no effect on daily gain as thin stillage DM concentration increased. No differences were detected in DMI or efficiency of gain when total DMI (basal diet and thin stillage) was considered. Carcass traits indicated a trend toward increased (P<.06) carcass fat with increasing thin stillage DM concentration. Results of Trial 2 indicated a linear improvement (P<.05) in apparent digestibility of DM, CP, NDF, and energy of the total diet (basal diet and thin stillage) as thin stillage DM concentration increased. We concluded that supplementing growing and finishing cattle with thin stillage reduced the amount of the basal diet required for gain and improved nutrient utilization.

Spherical hashing: binary code embedding with hyperspheres.

PubMed

Heo, Jae-Pil; Lee, Youngwoon; He, Junfeng; Chang, Shih-Fu; Yoon, Sung-Eui

2015-11-01

Many binary code embedding schemes have been actively studied recently, since they can provide efficient similarity search, and compact data representations suitable for handling large scale image databases. Existing binary code embedding techniques encode high-dimensional data by using hyperplane-based hashing functions. In this paper we propose a novel hypersphere-based hashing function, spherical hashing, to map more spatially coherent data points into a binary code compared to hyperplane-based hashing functions. We also propose a new binary code distance function, spherical Hamming distance, tailored for our hypersphere-based binary coding scheme, and design an efficient iterative optimization process to achieve both balanced partitioning for each hash function and independence between hashing functions. Furthermore, we generalize spherical hashing to support various similarity measures defined by kernel functions. Our extensive experiments show that our spherical hashing technique significantly outperforms state-of-the-art techniques based on hyperplanes across various benchmarks with sizes ranging from one to 75 million of GIST, BoW and VLAD descriptors. The performance gains are consistent and large, up to 100 percent improvements over the second best method among tested methods. These results confirm the unique merits of using hyperspheres to encode proximity regions in high-dimensional spaces. Finally, our method is intuitive and easy to implement.

Model-based classification of CPT data and automated lithostratigraphic mapping for high-resolution characterization of a heterogeneous sedimentary aquifer

PubMed Central

Mallants, Dirk; Batelaan, Okke; Gedeon, Matej; Huysmans, Marijke; Dassargues, Alain

2017-01-01

Cone penetration testing (CPT) is one of the most efficient and versatile methods currently available for geotechnical, lithostratigraphic and hydrogeological site characterization. Currently available methods for soil behaviour type classification (SBT) of CPT data however have severe limitations, often restricting their application to a local scale. For parameterization of regional groundwater flow or geotechnical models, and delineation of regional hydro- or lithostratigraphy, regional SBT classification would be very useful. This paper investigates the use of model-based clustering for SBT classification, and the influence of different clustering approaches on the properties and spatial distribution of the obtained soil classes. We additionally propose a methodology for automated lithostratigraphic mapping of regionally occurring sedimentary units using SBT classification. The methodology is applied to a large CPT dataset, covering a groundwater basin of ~60 km2 with predominantly unconsolidated sandy sediments in northern Belgium. Results show that the model-based approach is superior in detecting the true lithological classes when compared to more frequently applied unsupervised classification approaches or literature classification diagrams. We demonstrate that automated mapping of lithostratigraphic units using advanced SBT classification techniques can provide a large gain in efficiency, compared to more time-consuming manual approaches and yields at least equally accurate results. PMID:28467468

Model-based classification of CPT data and automated lithostratigraphic mapping for high-resolution characterization of a heterogeneous sedimentary aquifer.

PubMed

Rogiers, Bart; Mallants, Dirk; Batelaan, Okke; Gedeon, Matej; Huysmans, Marijke; Dassargues, Alain

2017-01-01

Cone penetration testing (CPT) is one of the most efficient and versatile methods currently available for geotechnical, lithostratigraphic and hydrogeological site characterization. Currently available methods for soil behaviour type classification (SBT) of CPT data however have severe limitations, often restricting their application to a local scale. For parameterization of regional groundwater flow or geotechnical models, and delineation of regional hydro- or lithostratigraphy, regional SBT classification would be very useful. This paper investigates the use of model-based clustering for SBT classification, and the influence of different clustering approaches on the properties and spatial distribution of the obtained soil classes. We additionally propose a methodology for automated lithostratigraphic mapping of regionally occurring sedimentary units using SBT classification. The methodology is applied to a large CPT dataset, covering a groundwater basin of ~60 km2 with predominantly unconsolidated sandy sediments in northern Belgium. Results show that the model-based approach is superior in detecting the true lithological classes when compared to more frequently applied unsupervised classification approaches or literature classification diagrams. We demonstrate that automated mapping of lithostratigraphic units using advanced SBT classification techniques can provide a large gain in efficiency, compared to more time-consuming manual approaches and yields at least equally accurate results.

Obtaining Large Columnar CdTe Grains and Long Lifetime on CdSe, MgZnO, or CdS Layers

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

Amarasinghe, Mahisha; Colegrove, Eric M; Moseley, John

CdTe solar cells have reached efficiencies comparable to multicrystalline silicon and produce electricity at costs competitive with traditional energy sources. Recent efficiency gains have come partly from shifting from the traditional CdS window layer to new materials such as CdSe and MgZnO, yet substantial headroom still exists to improve performance. Thin film technologies including Cu(In,Ga)Se2, perovskites, Cu2ZnSn(S,Se)4, and CdTe inherently have many grain boundaries that can form recombination centers and impede carrier transport; however, grain boundary engineering has been difficult and not practical. In this work, it is demonstrated that wide columnar grains reaching through the entire CdTe layer canmore » be achieved by aggressive postdeposition CdTe recrystallization. This reduces the grain structure constraints imposed by nucleation on nanocrystalline window layers and enables diverse window layers to be selected for other properties critical for electro-optical applications. Computational simulations indicate that increasing grain size from 1 to 7 um can be equivalent to decreasing grain-boundary recombination velocity by three orders of magnitude. Here, large high-quality grains enable CdTe lifetimes exceeding 50 ns.« less

Performance of a large size triple GEM detector at high particle rate for the CBM Experiment at FAIR

NASA Astrophysics Data System (ADS)

Adak, Rama Prasad; Kumar, Ajit; Dubey, Anand Kumar; Chattopadhyay, Subhasis; Das, Supriya; Raha, Sibaji; Samanta, Subhasis; Saini, Jogender

2017-02-01

In CBM Experiment at FAIR, dimuons will be detected by a Muon Chamber (MUCH) consisting of segmented absorbers of varying widths and tracking chambers sandwiched between the absorber-pairs. In this fixed target heavy-ion collision experiment, operating at highest interaction rate of 10 MHz for Au+Au collision, the inner region of the 1st detector will face a particle rate of 1 MHz/cm2. To operate at such a high particle density, GEM technology based detectors have been selected for the first two stations of MUCH. We have reported earlier the performance of several small-size GEM detector prototypes built at VECC for use in MUCH. In this work, we report on a large GEM prototype tested with proton beam of momentum 2.36 GeV/c at COSY-Jülich Germany. The detector was read out using nXYTER operated in self-triggering mode. An efficiency higher than 96% at ΔVGEM = 375.2 V was achieved. The variation of efficiency with the rate of incoming protons has been found to vary within 2% when tested up to a maximum rate of 2.8 MHz/cm2. The gain was found to be stable at high particle rate with a maximum variation of ∼9%.

High power diode laser Master Oscillator-Power Amplifier (MOPA)

NASA Technical Reports Server (NTRS)

Andrews, John R.; Mouroulis, P.; Wicks, G.

1994-01-01

High power multiple quantum well AlGaAs diode laser master oscillator - power amplifier (MOPA) systems were examined both experimentally and theoretically. For two pass operation, it was found that powers in excess of 0.3 W per 100 micrometers of facet length were achievable while maintaining diffraction-limited beam quality. Internal electrical-to-optical conversion efficiencies as high as 25 percent were observed at an internal amplifier gain of 9 dB. Theoretical modeling of multiple quantum well amplifiers was done using appropriate rate equations and a heuristic model of the carrier density dependent gain. The model gave a qualitative agreement with the experimental results. In addition, the model allowed exploration of a wider design space for the amplifiers. The model predicted that internal electrical-to-optical conversion efficiencies in excess of 50 percent should be achievable with careful system design. The model predicted that no global optimum design exists, but gain, efficiency, and optical confinement (coupling efficiency) can be mutually adjusted to meet a specific system requirement. A three quantum well, low optical confinement amplifier was fabricated using molecular beam epitaxial growth. Coherent beam combining of two high power amplifiers injected from a common master oscillator was also examined. Coherent beam combining with an efficiency of 93 percent resulted in a single beam having diffraction-limited characteristics. This beam combining efficiency is a world record result for such a system. Interferometric observations of the output of the amplifier indicated that spatial mode matching was a significant factor in the less than perfect beam combining. Finally, the system issues of arrays of amplifiers in a coherent beam combining system were investigated. Based upon experimentally observed parameters coherent beam combining could result in a megawatt-scale coherent beam with a 10 percent electrical-to-optical conversion efficiency.

Evaluation of the impact of changes in the hours of service regulation on efficiency, drivers, and safety

DOT National Transportation Integrated Search

1992-10-01

This paper examines the potential gains and losses of a change in hours of service rules for truck drivers. The authors conclude that drivers, carriers, and society in general would experience positive net gains from a change in the cumulative hours ...

Gain-adaptive vector quantization for medium-rate speech coding

NASA Technical Reports Server (NTRS)

Chen, J.-H.; Gersho, A.

1985-01-01

A class of adaptive vector quantizers (VQs) that can dynamically adjust the 'gain' of codevectors according to the input signal level is introduced. The encoder uses a gain estimator to determine a suitable normalization of each input vector prior to VQ coding. The normalized vectors have reduced dynamic range and can then be more efficiently coded. At the receiver, the VQ decoder output is multiplied by the estimated gain. Both forward and backward adaptation are considered and several different gain estimators are compared and evaluated. An approach to optimizing the design of gain estimators is introduced. Some of the more obvious techniques for achieving gain adaptation are substantially less effective than the use of optimized gain estimators. A novel design technique that is needed to generate the appropriate gain-normalized codebook for the vector quantizer is introduced. Experimental results show that a significant gain in segmental SNR can be obtained over nonadaptive VQ with a negligible increase in complexity.

Development and analysis of a STOL supersonic cruise fighter concept

NASA Technical Reports Server (NTRS)

Dollyhigh, S. M.; Foss, W. E., Jr.; Morris, S. J., Jr.; Walkley, K. B.; Swanson, E. E.; Robins, A. W.

1984-01-01

The application of advanced and emerging technologies to a fighter aircraft concept is described. The twin-boom fighter (TBF-1) relies on a two dimensional vectoring/reversing nozzle to provide STOL performance while also achieving efficient long range supersonic cruise. A key feature is that the propulsion package is placed so that the nozzle hinge line is near the aircraft center-of-gravity to allow large vector angles and, thus, provide large values of direct lift while minimizing the moments to be trimmed. The configurations name is derived from the long twin booms extending aft of the engine to the twin vertical tails which have a single horizontal tail mounted atop and between them. Technologies utilized were an advanced engine (1985 state-of-the-art), superplastic formed/diffusion bonded titanium structure, advanced controls/avionics/displays, supersonic wing design, and conformal weapons carriage. The integration of advanced technologies into this concept indicate that large gains in takeoff and landing performance, maneuver, acceleration, supersonic cruise speed, and range can be acieved relative to current fighter concepts.

A Method for Large Eddy Simulation of Acoustic Combustion Instabilities

NASA Astrophysics Data System (ADS)

Wall, Clifton; Moin, Parviz

2003-11-01

A method for performing Large Eddy Simulation of acoustic combustion instabilities is presented. By extending the low Mach number pressure correction method to the case of compressible flow, a numerical method is developed in which the Poisson equation for pressure is replaced by a Helmholtz equation. The method avoids the acoustic CFL condition by using implicit time advancement, leading to large efficiency gains at low Mach number. The method also avoids artificial damping of acoustic waves. The numerical method is attractive for the simulation of acoustics combustion instabilities, since these flows are typically at low Mach number, and the acoustic frequencies of interest are usually low. Additionally, new boundary conditions based on the work of Poinsot and Lele have been developed to model the acoustic effect of a long channel upstream of the computational inlet, thus avoiding the need to include such a channel in the computational domain. The turbulent combustion model used is the Level Set model of Duchamp de Lageneste and Pitsch for premixed combustion. Comparison of LES results to the reacting experiments of Besson et al. will be presented.

Structural Analysis of Biodiversity

PubMed Central

Sirovich, Lawrence; Stoeckle, Mark Y.; Zhang, Yu

2010-01-01

Large, recently-available genomic databases cover a wide range of life forms, suggesting opportunity for insights into genetic structure of biodiversity. In this study we refine our recently-described technique using indicator vectors to analyze and visualize nucleotide sequences. The indicator vector approach generates correlation matrices, dubbed Klee diagrams, which represent a novel way of assembling and viewing large genomic datasets. To explore its potential utility, here we apply the improved algorithm to a collection of almost 17000 DNA barcode sequences covering 12 widely-separated animal taxa, demonstrating that indicator vectors for classification gave correct assignment in all 11000 test cases. Indicator vector analysis revealed discontinuities corresponding to species- and higher-level taxonomic divisions, suggesting an efficient approach to classification of organisms from poorly-studied groups. As compared to standard distance metrics, indicator vectors preserve diagnostic character probabilities, enable automated classification of test sequences, and generate high-information density single-page displays. These results support application of indicator vectors for comparative analysis of large nucleotide data sets and raise prospect of gaining insight into broad-scale patterns in the genetic structure of biodiversity. PMID:20195371

A customizable class of colloidal-quantum-dot spasers and plasmonic amplifiers

PubMed Central

Kress, Stephan J. P.; Cui, Jian; Rohner, Patrik; Kim, David K.; Antolinez, Felipe V.; Zaininger, Karl-Augustin; Jayanti, Sriharsha V.; Richner, Patrizia; McPeak, Kevin M.; Poulikakos, Dimos; Norris, David J.

2017-01-01

Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays, and lasers. Consequently, when the spaser—a laser-like source of high-intensity, narrow-band surface plasmons—was first proposed, quantum dots were specified as the ideal plasmonic gain medium for overcoming the significant intrinsic losses of plasmons. Many subsequent spasers, however, have required a single material to simultaneously provide gain and define the plasmonic cavity, a design unable to accommodate quantum dots and other colloidal nanomaterials. In addition, these and other designs have been ill suited for integration with other elements in a larger plasmonic circuit, limiting their use. We develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum dot–based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create aberration-corrected plasmonic cavities with high quality factors at desired locations on an ultrasmooth silver substrate. We then incorporate quantum dots into these cavities via electrohydrodynamic printing or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons (0.65-nm linewidth at 630 nm, Q ~ 1000) above threshold. This signal is extracted, directed through an integrated amplifier, and focused at a nearby nanoscale tip, generating intense electromagnetic fields. More generally, our device platform can be straightforwardly deployed at different wavelengths, size scales, and geometries on large-area plasmonic chips for fundamental studies and applications. PMID:28948219

Realized gains from block-plot coastal Douglas-fir trials in the northern Oregon Cascades

Treesearch

Terrence Z. Ye; Keith J.S. Jayawickrama; J. Bradley St. Clair

2010-01-01

Realized gains for coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were evaluated using data collected from 15-year-old trees from five field trials planted in large block plots in the northern Oregon Cascades. Three populations with different genetic levels (elite--high predicted gain; intermediate--moderate predicted gain; and an...

Preliminary Assessment of Optimal Longitudinal-Mode Control for Drag Reduction through Distributed Aeroelastic Shaping

NASA Technical Reports Server (NTRS)

Ippolito, Corey; Nguyen, Nhan; Lohn, Jason; Dolan, John

2014-01-01

The emergence of advanced lightweight materials is resulting in a new generation of lighter, flexible, more-efficient airframes that are enabling concepts for active aeroelastic wing-shape control to achieve greater flight efficiency and increased safety margins. These elastically shaped aircraft concepts require non-traditional methods for large-scale multi-objective flight control that simultaneously seek to gain aerodynamic efficiency in terms of drag reduction while performing traditional command-tracking tasks as part of a complete guidance and navigation solution. This paper presents results from a preliminary study of a notional multi-objective control law for an aeroelastic flexible-wing aircraft controlled through distributed continuous leading and trailing edge control surface actuators. This preliminary study develops and analyzes a multi-objective control law derived from optimal linear quadratic methods on a longitudinal vehicle dynamics model with coupled aeroelastic dynamics. The controller tracks commanded attack-angle while minimizing drag and controlling wing twist and bend. This paper presents an overview of the elastic aircraft concept, outlines the coupled vehicle model, presents the preliminary control law formulation and implementation, presents results from simulation, provides analysis, and concludes by identifying possible future areas for research

A multi-dimensional, energy- and charge-conserving, nonlinearly implicit, electromagnetic Vlasov–Darwin particle-in-cell algorithm

DOE PAGES

Chen, G.; Chacón, L.

2015-08-11

For decades, the Vlasov–Darwin model has been recognized to be attractive for particle-in-cell (PIC) kinetic plasma simulations in non-radiative electromagnetic regimes, to avoid radiative noise issues and gain computational efficiency. However, the Darwin model results in an elliptic set of field equations that renders conventional explicit time integration unconditionally unstable. We explore a fully implicit PIC algorithm for the Vlasov–Darwin model in multiple dimensions, which overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. The finite-difference scheme for Darwin field equations and particle equations of motion is space–time-centered, employing particle sub-cycling and orbit-averaging. This algorithm conserves total energy, local charge,more » canonical-momentum in the ignorable direction, and preserves the Coulomb gauge exactly. An asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. Finally, we demonstrate the accuracy and efficiency properties of the algorithm with various numerical experiments in 2D–3V.« less

Benchmarking the cost efficiency of community care in Australian child and adolescent mental health services: implications for future benchmarking.

PubMed

Furber, Gareth; Brann, Peter; Skene, Clive; Allison, Stephen

2011-06-01

The purpose of this study was to benchmark the cost efficiency of community care across six child and adolescent mental health services (CAMHS) drawn from different Australian states. Organizational, contact and outcome data from the National Mental Health Benchmarking Project (NMHBP) data-sets were used to calculate cost per "treatment hour" and cost per episode for the six participating organizations. We also explored the relationship between intake severity as measured by the Health of the Nations Outcome Scales for Children and Adolescents (HoNOSCA) and cost per episode. The average cost per treatment hour was $223, with cost differences across the six services ranging from a mean of $156 to $273 per treatment hour. The average cost per episode was $3349 (median $1577) and there were significant differences in the CAMHS organizational medians ranging from $388 to $7076 per episode. HoNOSCA scores explained at best 6% of the cost variance per episode. These large cost differences indicate that community CAMHS have the potential to make substantial gains in cost efficiency through collaborative benchmarking. Benchmarking forums need considerable financial and business expertise for detailed comparison of business models for service provision.

Fast patient-specific Monte Carlo brachytherapy dose calculations via the correlated sampling variance reduction technique

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

Sampson, Andrew; Le Yi; Williamson, Jeffrey F.

2012-02-15

Purpose: To demonstrate potential of correlated sampling Monte Carlo (CMC) simulation to improve the calculation efficiency for permanent seed brachytherapy (PSB) implants without loss of accuracy. Methods: CMC was implemented within an in-house MC code family (PTRAN) and used to compute 3D dose distributions for two patient cases: a clinical PSB postimplant prostate CT imaging study and a simulated post lumpectomy breast PSB implant planned on a screening dedicated breast cone-beam CT patient exam. CMC tallies the dose difference, {Delta}D, between highly correlated histories in homogeneous and heterogeneous geometries. The heterogeneous geometry histories were derived from photon collisions sampled inmore » a geometrically identical but purely homogeneous medium geometry, by altering their particle weights to correct for bias. The prostate case consisted of 78 Model-6711 {sup 125}I seeds. The breast case consisted of 87 Model-200 {sup 103}Pd seeds embedded around a simulated lumpectomy cavity. Systematic and random errors in CMC were unfolded using low-uncertainty uncorrelated MC (UMC) as the benchmark. CMC efficiency gains, relative to UMC, were computed for all voxels, and the mean was classified in regions that received minimum doses greater than 20%, 50%, and 90% of D{sub 90}, as well as for various anatomical regions. Results: Systematic errors in CMC relative to UMC were less than 0.6% for 99% of the voxels and 0.04% for 100% of the voxels for the prostate and breast cases, respectively. For a 1 x 1 x 1 mm{sup 3} dose grid, efficiency gains were realized in all structures with 38.1- and 59.8-fold average gains within the prostate and breast clinical target volumes (CTVs), respectively. Greater than 99% of the voxels within the prostate and breast CTVs experienced an efficiency gain. Additionally, it was shown that efficiency losses were confined to low dose regions while the largest gains were located where little difference exists between the homogeneous and heterogeneous doses. On an AMD 1090T processor, computing times of 38 and 21 sec were required to achieve an average statistical uncertainty of 2% within the prostate (1 x 1 x 1 mm{sup 3}) and breast (0.67 x 0.67 x 0.8 mm{sup 3}) CTVs, respectively. Conclusions: CMC supports an additional average 38-60 fold improvement in average efficiency relative to conventional uncorrelated MC techniques, although some voxels experience no gain or even efficiency losses. However, for the two investigated case studies, the maximum variance within clinically significant structures was always reduced (on average by a factor of 6) in the therapeutic dose range generally. CMC takes only seconds to produce an accurate, high-resolution, low-uncertainly dose distribution for the low-energy PSB implants investigated in this study.« less

Industry costs and consolidation : efficiency gains and mergers in the railroad industry

DOT National Transportation Integrated Search

2003-06-01

Partial deregulation of the railroad industry substantially eased regulatory impediments to consolidation. Since partial deregulation, there has been a massive consolidation of firms in the railroad industry, which has been premised on efficiency gai...

Long-wavelength VCSELs: Power-efficient answer

NASA Astrophysics Data System (ADS)

Kapon, Eli; Sirbu, Alexei

2009-01-01

The commercialization of long-wavelength vertical-cavity surface-emitting lasers (VCSELs) is gaining new momentum as the telecoms market shifts from long-haul applications to local and access networks. These small, power-efficient devices offer several advantages over traditional edge-emitters.

Framing Innovation: The Role of Distributed Leadership in Gaining Acceptance of Large-Scale Technology Initiatives

ERIC Educational Resources Information Center

Turner, Henry J.

2014-01-01

This dissertation of practice utilized a multiple case-study approach to examine distributed leadership within five school districts that were attempting to gain acceptance of a large-scale 1:1 technology initiative. Using frame theory and distributed leadership theory as theoretical frameworks, this study interviewed each district's…

Ku-band field-effect power transistors

NASA Technical Reports Server (NTRS)

Taylor, G. C.; Huang, H. C.

1979-01-01

A single stage amplifier was developed using an 8 gate, 1200 micrometer width device to give a gain of 3.3 + or - 0.1 dB over the 14.4 to 15.4 GHz band with an output power of 0.48 W and 15% minimum efficiency with 0.255 W of input power. With two 8 gate devices combined and matched on the device carrier, using a lumped element format, a gain of 3 dB was attained over the 14.5 to 15.5 GHz band with a maximum efficiency of 9.9% for an output power of 0.8 W.

Enhanced Efficiency of Internal Combustion Engines By Employing Spinning Gas

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

Geyko, Vasily; Fisch, Nathaniel

2014-02-27

The efficiency of the internal combustion engine might be enhanced by employing spinning gas. A gas spinning at near sonic velocities has an effectively higher heat capacity, which allows practical fuel cycles, which are far from the Carnot efficiency, to approach more closely the Carnot efficiency. A gain in fuel efficiency of several percent is shown to be theoretically possible for the Otto and Diesel cycles. The use of a flywheel, in principle, could produce even greater increases in the efficiency.

Enhanced efficiency of internal combustion engines by employing spinning gas.

PubMed

Geyko, V I; Fisch, N J

2014-08-01

The efficiency of the internal combustion engine might be enhanced by employing spinning gas. A gas spinning at near sonic velocities has an effectively higher heat capacity, which allows practical fuel cycles, which are far from the Carnot efficiency, to approach more closely the Carnot efficiency. A remarkable gain in fuel efficiency is shown to be theoretically possible for the Otto and Diesel cycles. The use of a flywheel, in principle, could produce even greater increases in efficiency.

Modelling foraging movements of diving predators: a theoretical study exploring the effect of heterogeneous landscapes on foraging efficiency

PubMed Central

Bartoń, Kamil A.; Scott, Beth E.; Travis, Justin M.J.

2014-01-01

Foraging in the marine environment presents particular challenges for air-breathing predators. Information about prey capture rates, the strategies that diving predators use to maximise prey encounter rates and foraging success are still largely unknown and difficult to observe. As well, with the growing awareness of potential climate change impacts and the increasing interest in the development of renewable sources it is unknown how the foraging activity of diving predators such as seabirds will respond to both the presence of underwater structures and the potential corresponding changes in prey distributions. Motivated by this issue we developed a theoretical model to gain general understanding of how the foraging efficiency of diving predators may vary according to landscape structure and foraging strategy. Our theoretical model highlights that animal movements, intervals between prey capture and foraging efficiency are likely to critically depend on the distribution of the prey resource and the size and distribution of introduced underwater structures. For multiple prey loaders, changes in prey distribution affected the searching time necessary to catch a set amount of prey which in turn affected the foraging efficiency. The spatial aggregation of prey around small devices (∼ 9 × 9 m) created a valuable habitat for a successful foraging activity resulting in shorter intervals between prey captures and higher foraging efficiency. The presence of large devices (∼ 24 × 24 m) however represented an obstacle for predator movement, thus increasing the intervals between prey captures. In contrast, for single prey loaders the introduction of spatial aggregation of the resources did not represent an advantage suggesting that their foraging efficiency is more strongly affected by other factors such as the timing to find the first prey item which was found to occur faster in the presence of large devices. The development of this theoretical model represents a useful starting point to understand the energetic reasons for a range of potential predator responses to spatial heterogeneity and environmental uncertainties in terms of search behaviour and predator–prey interactions. We highlight future directions that integrated empirical and modelling studies should take to improve our ability to predict how diving predators will be impacted by the deployment of manmade structures in the marine environment. PMID:25250211

Association between gestational weight gain and perinatal outcomes in women with chronic hypertension.

PubMed

Yee, Lynn M; Caughey, Aaron B; Cheng, Yvonne W

2017-09-01

Gestational weight gain above or below the 2009 National Academy of Medicine guidelines has been associated with adverse maternal and neonatal outcomes. Although it has been well established that excess gestational weight gain is associated with the development of gestational hypertension and preeclampsia, the relationship between gestational weight gain and adverse perinatal outcomes among women with pregestational (chronic) hypertension is less clear. The objective of this study was to examine the relationship between gestational weight gain above and below National Academy of Medicine guidelines and perinatal outcomes in a large, population-based cohort of women with chronic hypertension. This is a population-based retrospective cohort study of women with chronic hypertension who had term, singleton, vertex births in the United States from 2012 through 2014. Prepregnancy body mass index was calculated using self-reported prepregnancy weight and height. Women were categorized into 4 groups based on gestational weight gain and prepregnancy body mass index: (1) weight gain less than, (2) weight gain within, (3) weight gain 1-19 lb in excess of, and (4) weight gain ≥20 lb in excess of the National Academy of Medicine guidelines. The χ 2 tests and multivariable logistic regression analysis were used for statistical comparisons. Stratified analyses by body mass index category were additionally performed. In this large birth cohort, 101,259 women met criteria for inclusion. Compared to hypertensive women who had gestational weight gain within guidelines, hypertensive women with weight gain ≥20 lb over National Academy of Medicine guidelines were more likely to have eclampsia (adjusted odds ratio, 1.93; 95% confidence interval, 1.54-2.42) and cesarean delivery (adjusted odds ratio, 1.60; 95% confidence interval, 1.50-1.70). Excess weight gain ≥20 lb over National Academy of Medicine guidelines was also associated with increased odds of 5-minute Apgar <7 (adjusted odds ratio, 1.29; 95% confidence interval, 1.13-1.47), neonatal intensive care unit admission (adjusted odds ratio, 1.23; 95% confidence interval, 1.14-1.33), and large-for-gestational-age neonates (adjusted odds ratio, 2.41; 95% confidence interval, 2.27-2.56) as well as decreased odds of small-for-gestational-age status (adjusted odds ratio, 0.52; 95% confidence interval, 0.46-0.58). Weight gain 1-19 lb over guidelines was associated with similar fetal growth outcomes although with a smaller effect size. In contrast, weight gain less than National Academy of Medicine guidelines was not associated with adverse maternal outcomes but was associated with increased odds of small for gestational age (adjusted odds ratio, 1.31; 95% confidence interval, 1.21-1.52) and decreased odds of large-for-gestational-age status (adjusted odds ratio, 0.86; 95% confidence interval, 0.81-0.92). Analysis of maternal and neonatal outcomes stratified by body mass index demonstrated similar findings. Women with chronic hypertension who gain less weight than National Academy of Medicine guidelines experience increased odds of small-for-gestational-age neonates, whereas excess weight gain ≥20 lb over National Academy of Medicine guidelines is associated with cesarean delivery, eclampsia, 5-minute Apgar <7, neonatal intensive care unit admission, and large-for-gestational-age neonates. Copyright © 2017 Elsevier Inc. All rights reserved.

Low dose digital X-ray imaging with avalanche amorphous selenium

NASA Astrophysics Data System (ADS)

Scheuermann, James R.; Goldan, Amir H.; Tousignant, Olivier; Léveillé, Sébastien; Zhao, Wei

2015-03-01

Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depth-independent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

Progress towards large gain-length products on the Li-like recombination scheme

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

Zeitoun, P.; Jamelot, G.; Carillon, A.

1995-05-01

Investigating possibilities of attaining large gain-length products on the recombination scheme using lithium-like ions, we have examined two approaches aimed at overcoming the problem of plasma non-uniformity susceptible to destroy gain by a number of processes. In the first approach we studied amplification on the transitions 5f-3d and 4f-3d in Li-like Al{sup 10+} plasma column produced by smoothing optics using lens arrays. Employing this device resulted in the gain holding up significantly longer than when no smoothing optics was used. Second, we have investigated numerically and experimentally the 5g-4f transition in Li-like S{sup 13+}, as the gain should be barelymore » affected by the plasma nonuniformities. Encouraging results were obtained and their various aspects are discussed.« less

A High Salt Diet Inhibits Obesity and Delays Puberty in the Female Rat

PubMed Central

Pitynski-Miller, Dori; Ross, Micah; Schmill, Margaret; Schambow, Rachel; Fuller, Teresa; Flynn, Francis W.; Skinner, Donal C.

2017-01-01

Background/Objectives Processed foods are considered major contributors to the worldwide obesity epidemic. In addition to high sugar and fat contents, processed foods contain large amounts of salt. Due to correlations with rising adiposity, salt has recently been proposed to be obesogenic. This study investigated three hypotheses: i) high salt contributes to weight gain and adiposity in juvenile female rats, ii) puberty onset would be altered because salt is known to affect neuronal systems involved in activating the reproductive system, and iii) enhanced adiposity will act synergistically with salt to drive early puberty onset. Design Female weanling rats (post-natal day 21, n=105) were fed a low fat/low salt diet, low fat/high salt diet, high fat/low salt diet, or a high salt/high fat diet for 24 days. Metabolic measures, including weight gain, food intake, fecal output, activity, and temperature were recorded in subsets of animals. Results Body weight, retroperitoneal and perirenal fat pad weight, and adipocyte size were all lower in animals fed high fat/high salt compared to animals fed high fat alone. Leptin levels were reduced in high fat/high salt fed animals compared to high fat/low salt fed animals. Daily calorie intake was higher initially but declined with adjusted food intake and was not different among groups after 5 days. Osmolality and corticosterone were not different among groups. Fecal analysis showed excess fat excretion and a decreased digestive efficiency in animals fed high fat/low salt but not in animals fed high fat/high salt. Although respiratory exchange ratio was reduced by high dietary fat or salt, aerobic resting metabolic rate was not affected by diet. High salt delayed puberty onset, regardless of dietary fat content. Conclusions Salt delays puberty and prevents the obesogenic effect of a high fat diet. The reduced weight gain evident in high salt fed animals is not due to differences in food intake or digestive efficiency. PMID:28674441

Fetal and neonatal programming of postnatal growth and feed efficiency in swine.

PubMed

Ji, Yun; Wu, Zhenlong; Dai, Zhaolai; Wang, Xiaolong; Li, Ju; Wang, Binggen; Wu, Guoyao

2017-01-01

Maternal undernutrition or overnutrition during pregnancy alters organ structure, impairs prenatal and neonatal growth and development, and reduces feed efficiency for lean tissue gains in pigs. These adverse effects may be carried over to the next generation or beyond. This phenomenon of the transgenerational impacts is known as fetal programming, which is mediated by stable and heritable alterations of gene expression through covalent modifications of DNA and histones without changes in DNA sequences (namely, epigenetics). The mechanisms responsible for the epigenetic regulation of protein expression and functions include chromatin remodeling; DNA methylation (occurring at the 5´-position of cytosine residues within CpG dinucleotides); and histone modifications (acetylation, methylation, phosphorylation, and ubiquitination). Like maternal malnutrition, undernutrition during the neonatal period also reduces growth performance and feed efficiency (weight gain:feed intake; also known as weight-gain efficiency) in postweaning pigs by 5-10%, thereby increasing the days necessary to reach the market body-weight. Supplementing functional amino acids (e.g., arginine and glutamine) and vitamins (e.g., folate) play a key role in activating the mammalian target of rapamycin signaling and regulating the provision of methyl donors for DNA and protein methylation. Therefore, these nutrients are beneficial for the dietary treatment of metabolic disorders in offspring with intrauterine growth restriction or neonatal malnutrition. The mechanism-based strategies hold great promise for the improvement of the efficiency of pork production and the sustainability of the global swine industry.

Gain-Compensating Circuit For NDE and Ultrasonics

NASA Technical Reports Server (NTRS)

Kushnick, Peter W.

1987-01-01

High-frequency gain-compensating circuit designed for general use in nondestructive evaluation and ultrasonic measurements. Controls gain of ultrasonic receiver as function of time to aid in measuring attenuation of samples with high losses; for example, human skin and graphite/epoxy composites. Features high signal-to-noise ratio, large signal bandwidth and large dynamic range. Control bandwidth of 5 MHz ensures accuracy of control signal. Currently being used for retrieval of more information from ultrasonic signals sent through composite materials that have high losses, and to measure skin-burn depth in humans.

RNA-Seq detection of differential gene expression in the rumen of beef steers associated with feed efficiency phenotypes

USDA-ARS?s Scientific Manuscript database

The efficient utilization of feedstuffs is an economically important trait in beef production. The rumen is important to the digestive process of steers interacting with feed, microbial populations, and volatile fatty acids indicating it may play a critical role in feed efficiency. To gain an unders...

Gaining Campaign Support through Peer Networking: An Impact Analysis of Energy Efficiency Projects in Malaysia

ERIC Educational Resources Information Center

Mustafa, Hasrina

2010-01-01

This article presents a comprehensive evaluation of the impact of two community projects on energy efficiency held in Malaysia in January 2008. Specifically, the study was undertaken to compare levels of attitudes and practices of energy efficiency between baseline and post-campaign survey; compare electricity consumptions before, one month after,…

Sampling error in timber surveys

Treesearch

Austin Hasel

1938-01-01

Various sampling strategies are evaluated for efficiency in an interior ponderosa pine forest. In a 5760 acre tract, efficiency was gained by stratifying into quarter acre blocks and sampling randomly from within. A systematic cruise was found to be superior for volume estimation.

2009 IOM guidelines for gestational weight gain: how well do they predict outcomes across ethnic groups?

PubMed

Khanolkar, Amal R; Hanley, Gillian E; Koupil, Ilona; Janssen, Patricia A

2017-11-13

To determine whether the Institute Of Medicine's (IOM) 2009 guidelines for weight-gain during pregnancy are predictive of maternal and infant outcomes in ethnic minority populations. We designed a population-based study using administrative data on 181,948 women who delivered live singleton births in Washington State between 2006-2008. We examined risks of gestational hypertension, preeclampsia/eclampsia, cesarean delivery, and extended hospital stay in White, Black, Native-American, East-Asian, Hispanic, South-Asian and Hawaiian/Pacific islander women according to whether they gained more or less weight during pregnancy than recommended by IOM guidelines. We also examined risks of neonatal outcomes including Apgar score <7 at 5 min, admission to NICU, requirement for ventilation, and a diagnosis of small or large for gestational age at birth. Gaining too much weight was associated with increased odds for gestational hypertension (adjusted OR (aOR) ranged between 1.53-2.22), preeclampsia/eclampsia (aOR 1.44-1.81), cesarean delivery (aOR 1.07-1.38) and extended hospital stay (aOR 1.06-1.28) in all ethnic groups. Gaining too little weight was associated with decreased odds for gestational hypertension and delivery by cesarean section in Whites, Blacks and Hispanics. Gaining less weight or more weight than recommended was associated with increased odds for small for gestational age and large for gestational age infants respectively, in all ethnic groups. Adherence to the 2009 IOM guidelines for weight gain during pregnancy reduces risk for various adverse maternal outcomes in all ethnic groups studied. However, the guidelines were less predictive of infant outcomes with the exception of small and large for gestational age. GWG: Gestational weight gain; IOM/NRC; Institute of Medicine and National Research Council; NICU: Neonatal intensive care need for ventilation; SGA: Small for gestational age; LGA: Large for gestational age; BERD: Birth Events Records Database; CHARS: Comprehensive Hospital Discharge Abstract Reporting System; ICD: International Classification of Disease; LMP: Last menstrual period; OR: Odds ratio.

3 CFR 13576 - Executive Order 13576 of June 13, 2011. Delivering an Efficient, Effective, and Accountable...

Code of Federal Regulations, 2012 CFR

2012-01-01

... performance and management reform gains my Administration has achieved, it is hereby ordered as follows... leaders on achieving ambitious improvements in high priority areas, and opening Government up to the... Government, my Administration will reinforce the performance and management reform gains achieved thus far...

Attentional Control in Visual Signal Detection: Effects of Abrupt-Onset and No-Onset Stimuli

ERIC Educational Resources Information Center

Sewell, David K.; Smith, Philip L.

2012-01-01

The attention literature distinguishes two general mechanisms by which attention can benefit performance: gain (or resource) models and orienting (or switching) models. In gain models, processing efficiency is a function of a spatial distribution of capacity or resources; in orienting models, an attentional spotlight must be aligned with the…

Effect of gain contouring in erbium-doped fiber amplifiers on bit error rate performance of wavelength-division multiplexing-based radio over fiber links

NASA Astrophysics Data System (ADS)

Jose, Tony; Narayanan, Vijayakumar

2018-03-01

Radio over fiber (RoF) systems use a large number of base stations (BSs) and a number of central stations (CSs), which are interlinked together to form the network. RoF systems use multiple wavelengths for communication between CSs or between CSs and BSs to facilitate the huge amount of data traffic due to the multiple services for a large number of users. When erbium-doped fiber amplifiers (EDFAs) are used as amplifiers in such wavelength-division multiplexed systems, the nonuniform gain spectrum of EDFAs causes instability to some of the channels while providing faithful amplification to other channels. To avoid this inconsistency, the gain spectrum of the amplifier needs to be uniform along the whole usable range of wavelengths. A gain contouring technique is proposed to provide uniform gain to all channels irrespective of wavelength. Optical add/drop multiplexers (OADMs) and different lengths of erbium-doped fibers are used to create such a gain contouring mechanism in the optical domain itself. The effect of a cascade of nonuniform gain amplifiers is studied, and the proposed system mitigates the adverse effects caused due to nonuniform gain-induced channel instability effectively.

Mixing due Pulsating Turbulent Jets

NASA Astrophysics Data System (ADS)

Grosshans, Holger; Nygård, Alexander; Fuchs, Laszlo

Combustion efficiency and the formation of soot and/or NOx in Internal- Combustion engines depends strongly on the local air/fuel mixture, the local flow conditions and temperature. Modern diesel engines employ high injection pressure for improved atomization, but mixing is controlled largely by the flow in the cylinder. By injecting the fuel in pulses one can gain control over the atomization, evaporation and the mixing of the gaseous fuel. We show that the pulsatile injection of fuel enhances fuel break-up and the entrainment of ambient air into the fuel stream. The entrainment level depends on fuel property, such as fuel/air viscosity and density ratio, fuel surface-tension, injection speed and injection sequencing. Examples of enhanced break-up and mixing are given.

Minority carrier diffusion and defects in InGaAsN grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Kurtz, Steven R.; Klem, J. F.; Allerman, A. A.; Sieg, R. M.; Seager, C. H.; Jones, E. D.

2002-02-01

To gain insight into the nitrogen-related defects of InGaAsN, nitrogen vibrational mode spectra, Hall mobilities, and minority carrier diffusion lengths are examined for InGaAsN (1.1 eV band gap) grown by molecular beam epitaxy (MBE). Annealing promotes the formation of In-N bonding, and lateral carrier transport is limited by large scale (≫mean free path) material inhomogeneities. Comparing solar cell quantum efficiencies with our earlier results for devices grown by metalorganic chemical vapor deposition (MOCVD), we find significant electron diffusion in the MBE material (reversed from the hole diffusion in MOCVD material), and minority carrier diffusion in InGaAsN cannot be explained by a "universal," nitrogen-related defect.

Ku-band high efficiency GaAs MMIC power amplifiers

NASA Technical Reports Server (NTRS)

Tserng, H. Q.; Witkowski, L. C.; Wurtele, M.; Saunier, Paul

1988-01-01

The development of Ku-band high efficiency GaAs MMIC power amplifiers is examined. Three amplifier modules operating over the 13 to 15 GHz frequency range are to be developed. The first MMIC is a 1 W variable power amplifier (VPA) with 35 percent efficiency. On-chip digital gain control is to be provided. The second MMIC is a medium power amplifier (MPA) with an output power goal of 1 W and 40 percent power-added efficiency. The third MMIC is a high power amplifier (HPA) with 4 W output power goal and 40 percent power-added efficiency. An output power of 0.36 W/mm with 49 percent efficiency was obtained on an ion implanted single gate MESFET at 15 GHz. On a dual gate MESFET, an output power of 0.42 W/mm with 27 percent efficiency was obtained. A mask set was designed that includes single stage, two stage, and three stage single gate amplifiers. A single stage 600 micron amplifier produced 0.4 W/mm output power with 40 percent efficiency at 14 GHz. A four stage dual gate amplifier generated 500 mW of output power with 20 dB gain at 17 GHz. A four-bit digital-to-analog converter was designed and fabricated which has an output swing of -3 V to +/- 1 V.

Dietary Sodium Suppresses Digestive Efficiency via the Renin-Angiotensin System.

PubMed

Weidemann, Benjamin J; Voong, Susan; Morales-Santiago, Fabiola I; Kahn, Michael Z; Ni, Jonathan; Littlejohn, Nicole K; Claflin, Kristin E; Burnett, Colin M L; Pearson, Nicole A; Lutter, Michael L; Grobe, Justin L

2015-06-11

Dietary fats and sodium are both palatable and are hypothesized to synergistically contribute to ingestive behavior and thereby obesity. Contrary to this hypothesis, C57BL/6J mice fed a 45% high fat diet exhibited weight gain that was inhibited by increased dietary sodium content. This suppressive effect of dietary sodium upon weight gain was mediated specifically through a reduction in digestive efficiency, with no effects on food intake behavior, physical activity, or resting metabolism. Replacement of circulating angiotensin II levels reversed the effects of high dietary sodium to suppress digestive efficiency. While the AT1 receptor antagonist losartan had no effect in mice fed low sodium, the AT2 receptor antagonist PD-123,319 suppressed digestive efficiency. Correspondingly, genetic deletion of the AT2 receptor in FVB/NCrl mice resulted in suppressed digestive efficiency even on a standard chow diet. Together these data underscore the importance of digestive efficiency in the pathogenesis of obesity, and implicate dietary sodium, the renin-angiotensin system, and the AT2 receptor in the control of digestive efficiency regardless of mouse strain or macronutrient composition of the diet. These findings highlight the need for greater understanding of nutrient absorption control physiology, and prompt more uniform assessment of digestive efficiency in animal studies of energy balance.

Declining spatial efficiency of global cropland nitrogen allocation

NASA Astrophysics Data System (ADS)

Mueller, Nathaniel D.; Lassaletta, Luis; Runck, Bryan C.; Billen, Gilles; Garnier, Josette; Gerber, James S.

2017-02-01

Efficiently allocating nitrogen (N) across space maximizes crop productivity for a given amount of N input and reduces N losses to the environment. Here we quantify changes in the global spatial efficiency of cropland N use by calculating historical trade-off frontiers relating N inputs to possible N yield assuming efficient allocation. Time series cropland N budgets from 1961 to 2009 characterize the evolution of N input-yield response functions across 12 regions and are the basis for constructing trade-off frontiers. Improvements in agronomic technology have substantially increased cropping system yield potentials and expanded N-driven crop production possibilities. However, we find that these gains are compromised by the declining spatial efficiency of N use across regions. Since the start of the Green Revolution, N inputs and yields have moved farther from the optimal frontier over time; in recent years (1994-2009), global N surplus has grown to a value that is 69% greater than what is possible with efficient N allocation between regions. To reflect regional pollution and agricultural development goals, we construct scenarios that restrict reallocation, finding that these changes only slightly decrease potential gains in nitrogen use efficiency. Our results are inherently conservative due to the regional unit of analysis, meaning a larger potential exists than is quantified here for cross-scale policies to promote spatially efficient N use.

Analysis of the Optimum Gain of a High-Pass L-Matching Network for Rectennas

PubMed Central

Jordana, Josep; Robert, Francesc-Josep; Berenguer, Jordi

2017-01-01

Rectennas, which mainly consist of an antenna, matching network, and rectifier, are used to harvest radiofrequency energy in order to power tiny sensor nodes, e.g., the nodes of the Internet of Things. This paper demonstrates for the first time, the existence of an optimum voltage gain for high-pass L-matching networks used in rectennas by deriving an analytical expression. The optimum gain is that which leads to maximum power efficiency of the rectenna. Here, apart from the L-matching network, a Schottky single-diode rectifier was used for the rectenna, which was optimized at 868 MHz for a power range from −30 dBm to −10 dBm. As the theoretical expression depends on parameters not very well-known a priori, an accurate search of the optimum gain for each power level was performed via simulations. Experimental results show remarkable power efficiencies ranging from 16% at −30 dBm to 55% at −10 dBm, which are for almost all the tested power levels the highest published in the literature for similar designs. PMID:28757592

Analysis of the Optimum Gain of a High-Pass L-Matching Network for Rectennas.

PubMed

Gasulla, Manel; Jordana, Josep; Robert, Francesc-Josep; Berenguer, Jordi

2017-07-25

Rectennas, which mainly consist of an antenna, matching network, and rectifier, are used to harvest radiofrequency energy in order to power tiny sensor nodes, e.g., the nodes of the Internet of Things. This paper demonstrates for the first time, the existence of an optimum voltage gain for high-pass L-matching networks used in rectennas by deriving an analytical expression. The optimum gain is that which leads to maximum power efficiency of the rectenna. Here, apart from the L-matching network, a Schottky single-diode rectifier was used for the rectenna, which was optimized at 868 MHz for a power range from -30 dBm to -10 dBm. As the theoretical expression depends on parameters not very well-known a priori, an accurate search of the optimum gain for each power level was performed via simulations. Experimental results show remarkable power efficiencies ranging from 16% at -30 dBm to 55% at -10 dBm, which are for almost all the tested power levels the highest published in the literature for similar designs.

Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)

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

Zhao Wei; Li Dan; Reznik, Alla

2005-09-15

An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoidmore » pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d{sub Se} and the applied electric field E{sub Se} of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E{sub Se} dependence of both avalanche gain and optical quantum efficiency of an 8 {mu}m HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E{sub Se}: (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 {mu}m can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy.« less

Does integration of HIV and SRH services achieve economies of scale and scope in practice? A cost function analysis of the Integra Initiative.

PubMed

Obure, Carol Dayo; Guinness, Lorna; Sweeney, Sedona; Initiative, Integra; Vassall, Anna

2016-03-01

Policy-makers have long argued about the potential efficiency gains and cost savings from integrating HIV and sexual reproductive health (SRH) services, particularly in resource-constrained settings with generalised HIV epidemics. However, until now, little empirical evidence exists on whether the hypothesised efficiency gains associated with such integration can be achieved in practice. We estimated a quadratic cost function using data obtained from 40 health facilities, over a 2-year-period, in Kenya and Swaziland. The quadratic specification enables us to determine the existence of economies of scale and scope. The empirical results reveal that at the current output levels, only HIV counselling and testing services are characterised by service-specific economies of scale. However, no overall economies of scale exist as all outputs are increased. The results also indicate cost complementarities between cervical cancer screening and HIV care; post-natal care and HIV care and family planning and sexually transmitted infection treatment combinations only. The results from this analysis reveal that contrary to expectation, efficiency gains from the integration of HIV and SRH services, if any, are likely to be modest. Efficiency gains are likely to be most achievable in settings that are currently delivering HIV and SRH services at a low scale with high levels of fixed costs. The presence of cost complementarities for only three service combinations implies that careful consideration of setting-specific clinical practices and the extent to which they can be combined should be made when deciding which services to integrate. NCT01694862. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Does integration of HIV and SRH services achieve economies of scale and scope in practice? A cost function analysis of the Integra Initiative

PubMed Central

Obure, Carol Dayo; Guinness, Lorna; Sweeney, Sedona; Initiative, Integra; Vassall, Anna

2016-01-01

Objective Policy-makers have long argued about the potential efficiency gains and cost savings from integrating HIV and sexual reproductive health (SRH) services, particularly in resource-constrained settings with generalised HIV epidemics. However, until now, little empirical evidence exists on whether the hypothesised efficiency gains associated with such integration can be achieved in practice. Methods We estimated a quadratic cost function using data obtained from 40 health facilities, over a 2-year-period, in Kenya and Swaziland. The quadratic specification enables us to determine the existence of economies of scale and scope. Findings The empirical results reveal that at the current output levels, only HIV counselling and testing services are characterised by service-specific economies of scale. However, no overall economies of scale exist as all outputs are increased. The results also indicate cost complementarities between cervical cancer screening and HIV care; post-natal care and HIV care and family planning and sexually transmitted infection treatment combinations only. Conclusions The results from this analysis reveal that contrary to expectation, efficiency gains from the integration of HIV and SRH services, if any, are likely to be modest. Efficiency gains are likely to be most achievable in settings that are currently delivering HIV and SRH services at a low scale with high levels of fixed costs. The presence of cost complementarities for only three service combinations implies that careful consideration of setting-specific clinical practices and the extent to which they can be combined should be made when deciding which services to integrate. Trial registration number NCT01694862. PMID:26438349

Single nucleotide polymorphisms and haplotypes associated with feed efficiency in beef cattle

PubMed Central

2013-01-01

Background General, breed- and diet-dependent associations between feed efficiency in beef cattle and single nucleotide polymorphisms (SNPs) or haplotypes were identified on a population of 1321 steers using a 50 K SNP panel. Genomic associations with traditional two-step indicators of feed efficiency – residual feed intake (RFI), residual average daily gain (RADG), and residual intake gain (RIG) – were compared to associations with two complementary one-step indicators of feed efficiency: efficiency of intake (EI) and efficiency of gain (EG). Associations uncovered in a training data set were evaluated on independent validation data set. A multi-SNP model was developed to predict feed efficiency. Functional analysis of genes harboring SNPs significantly associated with feed efficiency and network visualization aided in the interpretation of the results. Results For the five feed efficiency indicators, the numbers of general, breed-dependent, and diet-dependent associations with SNPs (P-value < 0.0001) were 31, 40, and 25, and with haplotypes were six, ten, and nine, respectively. Of these, 20 SNP and six haplotype associations overlapped between RFI and EI, and five SNP and one haplotype associations overlapped between RADG and EG. This result confirms the complementary value of the one and two-step indicators. The multi-SNP models included 89 SNPs and offered a precise prediction of the five feed efficiency indicators. The associations of 17 SNPs and 7 haplotypes with feed efficiency were confirmed on the validation data set. Nine clusters of Gene Ontology and KEGG pathway categories (mean P-value < 0.001) including, 9nucleotide binding; ion transport, phosphorous metabolic process, and the MAPK signaling pathway were overrepresented among the genes harboring the SNPs associated with feed efficiency. Conclusions The general SNP associations suggest that a single panel of genomic variants can be used regardless of breed and diet. The breed- and diet-dependent associations between SNPs and feed efficiency suggest that further refinement of variant panels require the consideration of the breed and management practices. The unique genomic variants associated with the one- and two-step indicators suggest that both types of indicators offer complementary description of feed efficiency that can be exploited for genome-enabled selection purposes. PMID:24066663

Bismuth-doped fibre amplifier operating between 1600 and 1800 nm

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

Firstov, S V; Alyshev, S V; Riumkin, K E

2015-12-31

We report the first bismuth-doped fibre amplifier operating between 1600 and 1800 nm, which utilises bidirectional pumping (co-propagating and counter-propagating pump beams) by laser diodes at a wavelength of 1550 nm. The largest gain coefficient of the amplifier is 23 dB, at a wavelength of 1710 nm. It has a noise figure of 7 dB, 3-dB gain bandwidth of 40 nm and gain efficiency of 0.1 dB mW{sup -1}. (letters)

Graphene plasmons embedded in a gain medium: layer and ribbon plasmons

NASA Astrophysics Data System (ADS)

Altares Menendez, Galaad; Rosolen, Gilles; Maes, Bjorn

2016-12-01

Graphene plasmonics has attracted much attention due to its remarkable properties such as tunable conductivity and extreme confinement. However, losses remain one of the major drawbacks to developing more efficient devices based on graphene plasmons. Here we show that when a gain medium is introduced around a 1D graphene sheet, lossless propagation can be achieved for a critical gain value. Both numerics and analytics are employed; and with the Drude approximation the analytical expression for this critical gain becomes remarkably simple. Furthermore, we examine a single 2D graphene nanoribbon within a gain environment. We report that the plasmonic resonant modes exhibit a spasing effect for a specific value of the surrounding gain. This feature is indicated by an absorption cross section that strongly increases and narrows. Finally, we manage to connect the ribbon results to the 1D sheet critical gain, by taking external coupling into account.

High peak-power kilohertz laser system employing single-stage multi-pass amplification

DOEpatents

Shan, Bing; Wang, Chun; Chang, Zenghu

2006-05-23

The present invention describes a technique for achieving high peak power output in a laser employing single-stage, multi-pass amplification. High gain is achieved by employing a very small "seed" beam diameter in gain medium, and maintaining the small beam diameter for multiple high-gain pre-amplification passes through a pumped gain medium, then leading the beam out of the amplifier cavity, changing the beam diameter and sending it back to the amplifier cavity for additional, high-power amplification passes through the gain medium. In these power amplification passes, the beam diameter in gain medium is increased and carefully matched to the pump laser's beam diameter for high efficiency extraction of energy from the pumped gain medium. A method of "grooming" the beam by means of a far-field spatial filter in the process of changing the beam size within the single-stage amplifier is also described.

An Exploration on Greenhouse Gas and Ammonia Production by Insect Species Suitable for Animal or Human Consumption

PubMed Central

Oonincx, Dennis G. A. B.; van Itterbeeck, Joost; Heetkamp, Marcel J. W.; van den Brand, Henry; van Loon, Joop J. A.; van Huis, Arnold

2010-01-01

Background Greenhouse gas (GHG) production, as a cause of climate change, is considered as one of the biggest problems society is currently facing. The livestock sector is one of the large contributors of anthropogenic GHG emissions. Also, large amounts of ammonia (NH3), leading to soil nitrification and acidification, are produced by livestock. Therefore other sources of animal protein, like edible insects, are currently being considered. Methodology/Principal Findings An experiment was conducted to quantify production of carbon dioxide (CO2) and average daily gain (ADG) as a measure of feed conversion efficiency, and to quantify the production of the greenhouse gases methane (CH4) and nitrous oxide (N2O) as well as NH3 by five insect species of which the first three are considered edible: Tenebrio molitor, Acheta domesticus, Locusta migratoria, Pachnoda marginata, and Blaptica dubia. Large differences were found among the species regarding their production of CO2 and GHGs. The insects in this study had a higher relative growth rate and emitted comparable or lower amounts of GHG than described in literature for pigs and much lower amounts of GHG than cattle. The same was true for CO2 production per kg of metabolic weight and per kg of mass gain. Furthermore, also the production of NH3 by insects was lower than for conventional livestock. Conclusions/Significance This study therefore indicates that insects could serve as a more environmentally friendly alternative for the production of animal protein with respect to GHG and NH3 emissions. The results of this study can be used as basic information to compare the production of insects with conventional livestock by means of a life cycle analysis. PMID:21206900

An exploration on greenhouse gas and ammonia production by insect species suitable for animal or human consumption.

PubMed

Oonincx, Dennis G A B; van Itterbeeck, Joost; Heetkamp, Marcel J W; van den Brand, Henry; van Loon, Joop J A; van Huis, Arnold

2010-12-29

Greenhouse gas (GHG) production, as a cause of climate change, is considered as one of the biggest problems society is currently facing. The livestock sector is one of the large contributors of anthropogenic GHG emissions. Also, large amounts of ammonia (NH(3)), leading to soil nitrification and acidification, are produced by livestock. Therefore other sources of animal protein, like edible insects, are currently being considered. An experiment was conducted to quantify production of carbon dioxide (CO₂) and average daily gain (ADG) as a measure of feed conversion efficiency, and to quantify the production of the greenhouse gases methane (CH₄) and nitrous oxide (N₂O) as well as NH₃ by five insect species of which the first three are considered edible: Tenebrio molitor, Acheta domesticus, Locusta migratoria, Pachnoda marginata, and Blaptica dubia. Large differences were found among the species regarding their production of CO₂ and GHGs. The insects in this study had a higher relative growth rate and emitted comparable or lower amounts of GHG than described in literature for pigs and much lower amounts of GHG than cattle. The same was true for CO₂ production per kg of metabolic weight and per kg of mass gain. Furthermore, also the production of NH₃ by insects was lower than for conventional livestock. This study therefore indicates that insects could serve as a more environmentally friendly alternative for the production of animal protein with respect to GHG and NH₃ emissions. The results of this study can be used as basic information to compare the production of insects with conventional livestock by means of a life cycle analysis.

Adaptive Flight Control Design with Optimal Control Modification on an F-18 Aircraft Model

NASA Technical Reports Server (NTRS)

Burken, John J.; Nguyen, Nhan T.; Griffin, Brian J.

2010-01-01

In the presence of large uncertainties, a control system needs to be able to adapt rapidly to regain performance. Fast adaptation is referred to as the implementation of adaptive control with a large adaptive gain to reduce the tracking error rapidly; however, a large adaptive gain can lead to high-frequency oscillations which can adversely affect the robustness of an adaptive control law. A new adaptive control modification is presented that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. The modification is based on the minimization of the Y2 norm of the tracking error, which is formulated as an optimal control problem. The optimality condition is used to derive the modification using the gradient method. The optimal control modification results in a stable adaptation and allows a large adaptive gain to be used for better tracking while providing sufficient robustness. A damping term (v) is added in the modification to increase damping as needed. Simulations were conducted on a damaged F-18 aircraft (McDonnell Douglas, now The Boeing Company, Chicago, Illinois) with both the standard baseline dynamic inversion controller and the adaptive optimal control modification technique. The results demonstrate the effectiveness of the proposed modification in tracking a reference model.

New results for temperature rise in gain medium of operating DPAL causing its degradation

NASA Astrophysics Data System (ADS)

Zhdanov, B. V.; Rotondaro, M. D.; Shaffer, M. K.; Knize, R. J.

2017-10-01

Diode Pumped Alkali Laser (DPAL) is one of the main candidates for development of a high power directed energy system producing laser beam from a single aperture with high spatial quality. Currently, several groups in the US and abroad demonstrated DPAL systems with kW level output power and efficiency higher than 50%. At the same time, the DPAL power scaling experiments revealed some limiting effects, which require detailed study to understand the nature of these effects and ways to mitigate them. Examples of such effects are output power degradation in time, alkali cell windows and gain medium contamination and damage that causes lasing efficiency decrease or even lasing termination. These problems can be connected to thermal effects, ionization, chemical interactions between the gain medium components and alkali cells materials. Study of all these and, possibly, other limiting effects and ways to mitigate them is very important for high power DPAL development. In this paper we present our new results of experiments on measurements of the temperature rise in the gain medium of operating DPAL leading to the output power degradation even before visible damage in the gain cell occurs. This degradation can be both recoverable and non-recoverable, depending on operation conditions and the system design.

Energy efficiency evaluation of hospital building office

NASA Astrophysics Data System (ADS)

Fitriani, Indah; Sangadji, Senot; Kristiawan, S. A.

2017-01-01

One of the strategy employed in building design is reducing energy consumption while maintaining the best comfort zone in building indoor climate. The first step to improve office buildings energy performance by evaluating its existing energy usage using energy consumption intensity (Intensitas Konsumsi Energi, IKE) index. Energy evaluation of office building for hospital dr. Sayidiman at Kabupaten Magetan has been carried out in the initial investigation. The office building is operated with active cooling (air conditioning, AC) and use limited daylighting which consumes 14.61 kWh/m2/month. This IKE value is attributed into a slightly inefficient category. Further investigation was carried out by modeling and simulating thermal energy load and room lighting in every building zone using of Ecotect from Autodesk. Three scenarios of building energy and lighting retrofit have been performed simulating representing energy efficiency using cross ventilation, room openings, and passive cooling. The results of the numerical simulation indicate that the third scenario by employing additional windows, reflector media and skylight exhibit the best result and in accordance with SNI 03-6575-2001 lighting standard. Total thermal load of the existing building which includes fabric gains, indirect solar gains, direct solar gains, ventilation fans, internal gains, inter-zonal gains and cooling load were 162,145.40 kWh. Based on the three scenarios, the thermal load value (kWh) obtained was lowest achieved scenario 2 with the thermal value of 117,539.08 kWh.The final results are interpreted from the total energy emissions evaluated using the Ecotect software, the heating and cooling demand value and specific design of the windows are important factors to determine the energy efficiency of the buildings.

Strategic planning to reduce the burden of stroke among veterans: using simulation modeling to inform decision making.

PubMed

Lich, Kristen Hassmiller; Tian, Yuan; Beadles, Christopher A; Williams, Linda S; Bravata, Dawn M; Cheng, Eric M; Bosworth, Hayden B; Homer, Jack B; Matchar, David B

2014-07-01

Reducing the burden of stroke is a priority for the Veterans Affairs Health System, reflected by the creation of the Veterans Affairs Stroke Quality Enhancement Research Initiative. To inform the initiative's strategic planning, we estimated the relative population-level impact and efficiency of distinct approaches to improving stroke care in the US Veteran population to inform policy and practice. A System Dynamics stroke model of the Veteran population was constructed to evaluate the relative impact of 15 intervention scenarios including both broad and targeted primary and secondary prevention and acute care/rehabilitation on cumulative (20 years) outcomes including quality-adjusted life years (QALYs) gained, strokes prevented, stroke fatalities prevented, and the number-needed-to-treat per QALY gained. At the population level, a broad hypertension control effort yielded the largest increase in QALYs (35,517), followed by targeted prevention addressing hypertension and anticoagulation among Veterans with prior cardiovascular disease (27,856) and hypertension control among diabetics (23,100). Adjusting QALYs gained by the number of Veterans needed to treat, thrombolytic therapy with tissue-type plasminogen activator was most efficient, needing 3.1 Veterans to be treated per QALY gained. This was followed by rehabilitation (3.9) and targeted prevention addressing hypertension and anticoagulation among those with prior cardiovascular disease (5.1). Probabilistic sensitivity analysis showed that the ranking of interventions was robust to uncertainty in input parameter values. Prevention strategies tend to have larger population impacts, though interventions targeting specific high-risk groups tend to be more efficient in terms of number-needed-to-treat per QALY gained. © 2014 American Heart Association, Inc.

Strategic Planning to Reduce the Burden of Stroke among Veterans: Using Simulation Modeling to Inform Decision Making

PubMed Central

Lich, Kristen Hassmiller; Tian, Yuan; Beadles, Christopher A.; Williams, Linda S.; Bravata, Dawn M.; Cheng, Eric M.; Bosworth, Hayden B.; Homer, Jack B.; Matchar, David B.

2014-01-01

Background and Purpose Reducing the burden of stroke is a priority for the Veterans Affairs (VA) Health System, reflected by the creation of the VA Stroke Quality Enhancement Research Initiative (QUERI). To inform the initiative's strategic planning, we estimated the relative population-level impact and efficiency of distinct approaches to improving stroke care in the United States Veteran population to inform policy and practice. Methods A System Dynamics stroke model of the Veteran population was constructed to evaluate the relative impact of 15 intervention scenarios including both broad and targeted primary and secondary prevention and acute care/rehabilitation on cumulative (20-year) outcomes including quality-adjusted life years (QALYs) gained, strokes prevented, stroke fatalities prevented and the number-needed-to-treat (NNT) per QALY gained. Results At the population level, a broad hypertension control effort yielded the largest increase in QALYs (35,517), followed by targeted prevention addressing hypertension and anticoagulation among Veterans with prior cardiovascular disease (27,856) and hypertension control among diabetics (23,100). Adjusting QALYs gained by the number of Veterans needed to treat, thrombolytic therapy with tissue plasminogen activator was most efficient, needing 3.1 Veterans to be treated per QALY gained. This was followed by rehabilitation (3.9) and targeted prevention addressing hypertension and anticoagulation among those with prior cardiovascular disease (5.1). Probabilistic sensitivity analysis showed that the ranking of interventions was robust to uncertainty in input parameter values. Conclusions Prevention strategies tend to have larger population impacts, though interventions targeting specific high-risk groups tend to be more efficient in terms of NNT per QALY gained. PMID:24923722

Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors

PubMed Central

Kasap, Safa; Frey, Joel B.; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S.; Rowlands, John A.

2011-01-01

In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been recently demonstrated with excellent avalanche gains; the latter is expected to lead to a number of novel imaging device applications that would be quantum noise limited. While passive pixel sensors use one TFT (thin film transistor) as a switch at the pixel, active pixel sensors (APSs) have two or more transistors and provide gain at the pixel level. The advantages of APS based x-ray imagers are also discussed with examples. PMID:22163893

Life cycle efficiency of beef production: II. Relationship of cow efficiency ratios to traits of the dam and progeny weaned.

PubMed

Davis, M E; Rutledge, J J; Cundiff, L V; Hauser, E R

1983-10-01

Several measures of life cycle cow efficiency were calculated using weights and individual feed consumptions recorded on 160 dams of beef, dairy and beef X dairy breeding and their progeny. Ratios of output to input were used to estimate efficiency, where outputs included weaning weights of progeny plus salvage value of the dam and inputs included creep feed consumed by progeny plus feed consumed by the dam over her entire lifetime. In one approach to estimating efficiency, inputs and outputs were weighted by probabilities that were a function of the cow herd age distribution and percentage calf crop in a theoretical herd. The second approach to estimating cow efficiency involved dividing the sum of the weights by the sum of the feed consumption values, with all pieces of information being given equal weighting. Relationships among efficiency estimates and various traits of dams and progeny were examined. Weights, heights, and weight:height ratios of dams at 240 d of age were not correlated significantly with subsequent efficiency of calf production, indicating that indirect selection for lifetime cow efficiency at an early age based on these traits would be ineffective. However, females exhibiting more efficient weight gains from 240 d to first calving tended to become more efficient dams. Correlations of efficiency with weight of dam at calving and at weaning were negative and generally highly significant. Height at withers was negatively related to efficiency. Ratio of weight to height indicated that fatter dams generally were less efficient. The effect of milk production on efficiency depended upon the breed combinations involved. Dams calving for the first time at an early age and continuing to calve at short intervals were superior in efficiency. Weaning rate was closely related to life cycle efficiency. Large negative correlations between efficiency and feed consumption of dams were observed, while correlations of efficiency with progeny weights and feed consumptions in individual parities tended to be positive though nonsignificant. However, correlations of efficiency with accumulative progeny weights and feed consumptions generally were significant.

Study of Potential Cost Reductions Resulting from Super-Large-Scale Manufacturing of PV Modules: Final Subcontract Report, 7 August 2003--30 September 2004

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

Keshner, M. S.; Arya, R.

2004-10-01

Hewlett Packard has created a design for a ''Solar City'' factory that will process 30 million sq. meters of glass panels per year and produce 2.1-3.6 GW of solar panels per year-100x the volume of a typical, thin-film, solar panel manufacturer in 2004. We have shown that with a reasonable selection of materials, and conservative assumptions, this ''Solar City'' can produce solar panels and hit the price target of $1.00 per peak watt (6.5x-8.5x lower than prices in 2004) as the total price for a complete and installed rooftop (or ground mounted) solar energy system. This breakthrough in the pricemore » of solar energy comes without the need for any significant new invention. It comes entirely from the manufacturing scale of a large plant and the cost savings inherent in operating at such a large manufacturing scale. We expect that further optimizations from these simple designs will lead to further improvements in cost. The manufacturing process and cost depend on the choice for the active layer that converts sunlight into electricity. The efficiency by which sunlight is converted into electricity can range from 7% to 15%. This parameter has a large effect on the overall price per watt. There are other impacts, as well, and we have attempted to capture them without creating undue distractions. Our primary purpose is to demonstrate the impact of large-scale manufacturing. This impact is largely independent of the choice of active layer. It is not our purpose to compare the pro's and con's for various types of active layers. Significant improvements in cost per watt can also come from scientific advances in active layers that lead to higher efficiency. But, again, our focus is on manufacturing gains and not on the potential advances in the basic technology.« less

Parallel workflow manager for non-parallel bioinformatic applications to solve large-scale biological problems on a supercomputer.

PubMed

Suplatov, Dmitry; Popova, Nina; Zhumatiy, Sergey; Voevodin, Vladimir; Švedas, Vytas

2016-04-01

Rapid expansion of online resources providing access to genomic, structural, and functional information associated with biological macromolecules opens an opportunity to gain a deeper understanding of the mechanisms of biological processes due to systematic analysis of large datasets. This, however, requires novel strategies to optimally utilize computer processing power. Some methods in bioinformatics and molecular modeling require extensive computational resources. Other algorithms have fast implementations which take at most several hours to analyze a common input on a modern desktop station, however, due to multiple invocations for a large number of subtasks the full task requires a significant computing power. Therefore, an efficient computational solution to large-scale biological problems requires both a wise parallel implementation of resource-hungry methods as well as a smart workflow to manage multiple invocations of relatively fast algorithms. In this work, a new computer software mpiWrapper has been developed to accommodate non-parallel implementations of scientific algorithms within the parallel supercomputing environment. The Message Passing Interface has been implemented to exchange information between nodes. Two specialized threads - one for task management and communication, and another for subtask execution - are invoked on each processing unit to avoid deadlock while using blocking calls to MPI. The mpiWrapper can be used to launch all conventional Linux applications without the need to modify their original source codes and supports resubmission of subtasks on node failure. We show that this approach can be used to process huge amounts of biological data efficiently by running non-parallel programs in parallel mode on a supercomputer. The C++ source code and documentation are available from http://biokinet.belozersky.msu.ru/mpiWrapper .

A video multitracking system for quantification of individual behavior in a large fish shoal: advantages and limits.

PubMed

Delcourt, Johann; Becco, Christophe; Vandewalle, Nicolas; Poncin, Pascal

2009-02-01

The capability of a new multitracking system to track a large number of unmarked fish (up to 100) is evaluated. This system extrapolates a trajectory from each individual and analyzes recorded sequences that are several minutes long. This system is very efficient in statistical individual tracking, where the individual's identity is important for a short period of time in comparison with the duration of the track. Individual identification is typically greater than 99%. Identification is largely efficient (more than 99%) when the fish images do not cross the image of a neighbor fish. When the images of two fish merge (occlusion), we consider that the spot on the screen has a double identity. Consequently, there are no identification errors during occlusions, even though the measurement of the positions of each individual is imprecise. When the images of these two merged fish separate (separation), individual identification errors are more frequent, but their effect is very low in statistical individual tracking. On the other hand, in complete individual tracking, where individual fish identity is important for the entire trajectory, each identification error invalidates the results. In such cases, the experimenter must observe whether the program assigns the correct identification, and, when an error is made, must edit the results. This work is not too costly in time because it is limited to the separation events, accounting for fewer than 0.1% of individual identifications. Consequently, in both statistical and rigorous individual tracking, this system allows the experimenter to gain time by measuring the individual position automatically. It can also analyze the structural and dynamic properties of an animal group with a very large sample, with precision and sampling that are impossible to obtain with manual measures.

Comparison of dairy beef genetics and dietary roughage levels.

PubMed

Lehmkuhler, J W; Ramos, M H

2008-06-01

The objectives of these trials were to investigate the performance of Jersey steers in relation to Holsteins under current management practices when fed diets differing in energy density and subsequent effects on carcass characteristics. In experiment 1, twelve Jersey and 12 Holstein steers were offered dietary treatments with differing roughage levels. Roughage levels investigated on a dry matter basis were 55% reduced to 25% versus 25% followed by 12.5% (HIGH and LOW, respectively) with all animals receiving the same finishing diet containing 6.5% roughage. Holstein steers were heavier than Jerseys at the initiation of the trial (228 vs. 116 kg). A diet response was observed for gain efficiency during the first period in which LOW was greater than HIGH. Holstein steers had higher dry matter intakes and rates of gain than Jerseys. However, gain efficiency was better for Jersey steers during the first and last periods. Carcass traits were influenced by breed but not diet. Holsteins had heavier hot carcass weights, greater dressing percentages, more backfat, and larger longissimus muscle area, whereas marbling scores were similar to Jerseys. The increased efficiency of Jersey steers and significant reduction in carcass value due to light carcass weights suggested that Jersey steers should be fed to heavier live weights. Experiment 2 utilized 85 steers to investigate continuous feeding of a low-roughage, high-concentrate diet versus a phase-feeding strategy. Jersey (n = 40) and Holstein (n = 45) steers were assigned to a diet containing 20% corn silage on a dry matter basis (HEN) or a phase-feeding program (PHASE) in which corn silage was reduced from 60 to 40% followed by the same diet as HEN. Initial body weights were similar for dietary treatments but differed by breed. A diet response was observed for live weight at the end of the first and second period, first period average daily gain (ADG), overall ADG, and days on feed with HEN having higher ADG than PHASE and fewer days on feed. Breed affected all body weight and gain variables with Holsteins being heavier and gaining more rapidly than Jersey steers. Jersey carcasses were lighter, had the highest percentage trim loss, least amount of backfat, and lowest numerical yield grade. Holstein steers had a greater propensity for gain, whereas the Jersey steers were equally or more efficient. These findings suggest that phase feeding Jersey steers higher-roughage diets has minimal effect on carcass traits.

Characterization of the Hamamatsu 8" R5912-MOD Photomultiplier tube

NASA Astrophysics Data System (ADS)

Kaptanoglu, Tanner

2018-05-01

Current and future neutrino and direct detection dark matter experiments hope to take advantage of improving technologies in photon detection. Many of these detectors are large, monolithic optical detectors that use relatively low-cost, large-area, and efficient photomultiplier tubes (PMTs). A candidate PMT for future experiments is a newly developed prototype Hamamatsu PMT, the R5912-MOD. In this paper we describe measurements made of the single photoelectron time and charge response of the R5912-MOD, as well as detail some direct comparisons to similar PMTs. Most of these measurements were performed on three R5912-MOD PMTs operating at gains close to 1 × 107. The transit time spread (σ) and the charge peak-to-valley were measured to be on average 680ps and 4.2 respectively. The results of this paper show the R5912-MOD is an excellent candidate for future experiments in several regards, particularly due to its narrow spread in timing.

Control of fluxes in metabolic networks.

PubMed

Basler, Georg; Nikoloski, Zoran; Larhlimi, Abdelhalim; Barabási, Albert-László; Liu, Yang-Yu

2016-07-01

Understanding the control of large-scale metabolic networks is central to biology and medicine. However, existing approaches either require specifying a cellular objective or can only be used for small networks. We introduce new coupling types describing the relations between reaction activities, and develop an efficient computational framework, which does not require any cellular objective for systematic studies of large-scale metabolism. We identify the driver reactions facilitating control of 23 metabolic networks from all kingdoms of life. We find that unicellular organisms require a smaller degree of control than multicellular organisms. Driver reactions are under complex cellular regulation in Escherichia coli, indicating their preeminent role in facilitating cellular control. In human cancer cells, driver reactions play pivotal roles in malignancy and represent potential therapeutic targets. The developed framework helps us gain insights into regulatory principles of diseases and facilitates design of engineering strategies at the interface of gene regulation, signaling, and metabolism. © 2016 Basler et al.; Published by Cold Spring Harbor Laboratory Press.

Richardson constant and electrostatics in transfer-free CVD grown few-layer MoS2/graphene barristor with Schottky barrier modulation >0.6eV

NASA Astrophysics Data System (ADS)

Jahangir, Ifat; Uddin, M. Ahsan; Singh, Amol K.; Koley, Goutam; Chandrashekhar, M. V. S.

2017-10-01

We demonstrate a large area MoS2/graphene barristor, using a transfer-free method for producing 3-5 monolayer (ML) thick MoS2. The gate-controlled diodes show good rectification, with an ON/OFF ratio of ˜103. The temperature dependent back-gated study reveals Richardson's coefficient to be 80.3 ± 18.4 A/cm2/K and a mean electron effective mass of (0.66 ± 0.15)m0. Capacitance and current based measurements show the effective barrier height to vary over a large range of 0.24-0.91 eV due to incomplete field screening through the thin MoS2. Finally, we show that this barristor shows significant visible photoresponse, scaling with the Schottky barrier height. A response time of ˜10 s suggests that photoconductive gain is present in this device, resulting in high external quantum efficiency.

Energy gain calculations in Penning fusion systems using a bounce-averaged Fokker-Planck model

NASA Astrophysics Data System (ADS)

Chacón, L.; Miley, G. H.; Barnes, D. C.; Knoll, D. A.

2000-11-01

In spherical Penning fusion devices, a spherical cloud of electrons, confined in a Penning-like trap, creates the ion-confining electrostatic well. Fusion energy gains for these systems have been calculated in optimistic conditions (i.e., spherically uniform electrostatic well, no collisional ion-electron interactions, single ion species) using a bounce-averaged Fokker-Planck (BAFP) model. Results show that steady-state distributions in which the Maxwellian ion population is dominant correspond to lowest ion recirculation powers (and hence highest fusion energy gains). It is also shown that realistic parabolic-like wells result in better energy gains than square wells, particularly at large well depths (>100 kV). Operating regimes with fusion power to ion input power ratios (Q-value) >100 have been identified. The effect of electron losses on the Q-value has been addressed heuristically using a semianalytic model, indicating that large Q-values are still possible provided that electron particle losses are kept small and well depths are large.

Computationally efficient multibody simulations

NASA Technical Reports Server (NTRS)

Ramakrishnan, Jayant; Kumar, Manoj

1994-01-01

Computationally efficient approaches to the solution of the dynamics of multibody systems are presented in this work. The computational efficiency is derived from both the algorithmic and implementational standpoint. Order(n) approaches provide a new formulation of the equations of motion eliminating the assembly and numerical inversion of a system mass matrix as required by conventional algorithms. Computational efficiency is also gained in the implementation phase by the symbolic processing and parallel implementation of these equations. Comparison of this algorithm with existing multibody simulation programs illustrates the increased computational efficiency.

Impact of microbial efficiency to predict MP supply when estimating protein requirements of growing beef cattle from performance.

PubMed

Watson, A K; Klopfenstein, T J; Erickson, G E; MacDonald, J C; Wilkerson, V A

2017-07-01

Data from 16 trials were compiled to calculate microbial CP (MCP) production and MP requirements of growing cattle on high-forage diets. All cattle were individually fed diets with 28% to 72% corn cobs in addition to either alfalfa, corn silage, or sorghum silage at 18% to 60% of the diet (DM basis). The remainder of the diet consisted of protein supplement. Source of protein within the supplement varied and included urea, blood meal, corn gluten meal, dry distillers grains, feather meal, meat and bone meal, poultry by-product meal, soybean meal, and wet distillers grains. All trials included a urea-only treatment. Intake of all cattle within an experiment was held constant, as a percentage of BW, established by the urea-supplemented group. In each trial the base diet (forage and urea supplement) was MP deficient. Treatments consisted of increasing amounts of test protein replacing the urea supplement. As protein in the diet increased, ADG plateaued. Among experiments, ADG ranged from 0.11 to 0.73 kg. Three methods of calculating microbial efficiency were used to determine MP supply. Gain was then regressed against calculated MP supply to determine MP requirement for maintenance and gain. Method 1 (based on a constant 13% microbial efficiency as used by the beef NRC model) predicted an MP maintenance requirement of 3.8 g/kg BW and 385 g MP/kg gain. Method 2 calculated microbial efficiency using low-quality forage diets and predicted MP requirements of 3.2 g/kg BW for maintenance and 448 g/kg for gain. Method 3 (based on an equation predicting MCP yield from TDN intake, proposed by the Beef Cattle Nutrient Requirements Model [BCNRM]) predicted MP requirements of 3.1 g/kg BW for maintenance and 342 g/kg for gain. The factorial method of calculating MP maintenance requirements accounts for scurf, endogenous urinary, and metabolic fecal protein losses and averaged 4.2 g/kg BW. Cattle performance data demonstrate formulating diets to meet the beef NRC model recommended MP maintenance requirement (3.8 g/kg S) works well when using 13% microbial efficiency. Therefore, a change in how microbial efficiency is calculated necessitates a change in the proposed MP maintenance requirement to not oversupply or undersupply RUP. Using the 2016 BCNRM to predict MCP production and formulate diets to meet MP requirements also requires changing the MP maintenance requirement to 3.1 g/kg BW.

Unsteady specific work and isentropic efficiency of a radial turbine driven by pulsed detonations

NASA Astrophysics Data System (ADS)

Rouser, Kurt P.

There has been longstanding government and industry interest in pressure-gain combustion for use in Brayton cycle based engines. Theoretically, pressure-gain combustion allows heat addition with reduced entropy loss. The pulsed detonation combustor (PDC) is a device that can provide such pressure-gain combustion and possibly replace typical steady deflagration combustors. The PDC is inherently unsteady, however, and comparisons with conventional steady deflagration combustors must be based upon time-integrated performance variables. In this study, the radial turbine of a Garrett automotive turbocharger was coupled directly to and driven, full admission, by a PDC in experiments fueled by hydrogen or ethylene. Data included pulsed cycle time histories of turbine inlet and exit temperature, pressure, velocity, mass flow, and enthalpy. The unsteady inlet flowfield showed momentary reverse flow, and thus unsteady accumulation and expulsion of mass and enthalpy within the device. The coupled turbine-driven compressor provided a time-resolved measure of turbine power. Peak power increased with PDC fill fraction, and duty cycle increased with PDC frequency. Cycle-averaged unsteady specific work increased with fill fraction and frequency. An unsteady turbine efficiency formulation is proposed, including heat transfer effects, enthalpy flux-weighted total pressure ratio, and ensemble averaging over multiple cycles. Turbine efficiency increased with frequency but was lower than the manufacturer reported conventional steady turbine efficiency.